A disposable (also called disposable product) is a product designed for a single use after which it is recycled or is disposed as solid waste. The term often implies cheapness and short-term convenience rather than medium to long-term durability. The term is also sometimes used for products that may last several months (ex. disposable air filters) to distinguish from similar products that last indefinitely (ex. washable air filters). Disposables are most often made from paper, plastic, cotton, or polystyrene foam.
Disposable cutlery and containers are products that are a part of our day-to-day life. Disposable items like cups, plates, saucers are being increasingly used.
A plastic material is any of a wide range of synthetic or semi-synthetic organic solids that are moldable. Plastics are typically organic polymers of high molecular mass, but they often contain other substances. They are usually synthetic, most commonly derived from petrochemicals, but many are partially natural.
Polypropylene (PP), also known as polypropene, is a thermoplastic polymer . This polyolefin is readily formed by polymerizing propylene with suitable catalysts, generally aluminum alkyl and titanium tetrachloride. Polypropylene properties vary according to molecular weight, method of production, and the copolymers involved.
Uses include protective packaging (such as packing peanuts and CD and DVD cases), containers (such as “clamshells”), lids, bottles, trays, tumblers, and disposable cutlery. As a thermoplastic polymer, polystyrene is in a solid (glassy) state at room temperature but flows if heated above about 100°C, its glass transition temperature. It becomes rigid again when cooled. This temperature behavior is exploited for extrusion, and also for molding and vacuum forming, since it can be cast into molds with fine detail.
Disposable Bottle has been a widely used commodity in the world. Polyethylene Terephthalate (PET) is the most popular material used for manufacturing plastic bottles and containers in the world. PET is a thermoplastic polymer that can be either opaque or transparent, depending on the exact material composition.
PET is commonly implemented for bottle because it has good chemical stability, and also a good barrier for moisture and gas. PET bottle is commonly manufactured through injection molding and extrusion process. PET bottle are extremely light due to the low density. The processing of PET bottle is a lot easier due to good flow when molded allowing high speed manufacturing. It is strong enough for the water container application because it can withstand high internal pressure (5 to 6 bars) while also scratch resistant.
A paper cup is a cup made out of paper and often lined with plastic or wax to prevent liquid from leaking out or soaking through the paper. It may be made of recycled paper and is widely used around the world.
Paper cups for hot drinks are made waterproof by coating the walls of the cup with clay, making the paper water-resistant. However, this resulted in drinks smelling and tasting of cardboard whereas cups for cold drinks are coated with thin layer of polyethylene (PE).
Mostly used raw material is used engineered thermoplastic or special grade papers or wooden material or aluminum coated paper as raw material. Plenty of raw materials are available in India. Plant and machineries, which is required for manufacturing of the above mentioned products, are also available indigenously in our country. There are few technical experts available in this field that can provide total manufacturing process technology.
Facial Tissue, Wet Wipes and Toilet Rolls
Rolls are slitted according to size and dimension and then liquid detergent and other solvents are spread over the tissue paper to make wetting and then it make rolled form and pack it in the close pack with one side opening lid. Packing materials are made by using polymer resin and labeled by printed-paper. In the manufacturing process there is very negligible amount pollution obtained, which can be easily controlled.
A wet wipe, also known as a wet towel, or a moist towelette, is a small moistened piece of paper or cloth that often comes folded and individually wrapped for convenience. Wet wipes are used for cleaning purposes, like personal hygiene or household cleaning.
A plastic cup is a disposable cup made of plastic. It is most commonly used as a container to hold beverages. Plastic cups seem to be the best environmentally friendly option as most plastic cups are recyclable. If it is not recyclable, it can still be grounded up and used as filler for other products. Plastic is also a much lighter material so there is less transportation and fuel costs needed.
Plastics cups are used in social gatherings to serve beverages, storing liquids, convenient to be used during travelling etc.
Disposable Banana Leaf Plates
Banana leaf plate making is a state-of-the-art to develop biodegradable and compostable alternatives to petrochemical based plastics and polystyrene. A biodegradable product is one that’s broken down safely and relatively quickly by microbial activity into CO2, Water and Biomass – that’s bacteria, moulds and fungi: good stuff!
Baby Diaper and Sanitary Napkin
Diapers are primarily worn by children who are not yet potty trained or experience bedwetting. However, they can also be used by adults with incontinence or in certain circumstances where access to a toilet is unavailable. These can include the elderly, those with a physical or mental disability, and people working in extreme conditions such as astronauts. It is not uncommon for people to wear diapers under dry suits.
Some disposable diapers include fragrances, lotions or essential oils in order to help mask the scent of a soiled diaper or to protect the skin.
These products are generally used by females during their menstruation cycle, by newly born babies who are not yet potty trained, by adults those with physical or mental disability, and people working in extreme conditions such as astronauts etc.
These are the products that are difficult to avoid. There are times when reusable items are not practical or allowed, that time we realize the importance of disposable items. These products are easy to use, easy to dispose off, saves time, hygienic, reusable etc.
Plastics are an important part of everyday life; products made from plastics range from sophisticated products, such as prosthetic hip and knee joints, to disposable food utensils. One of the reasons for the great popularity of plastics in a wide variety of industrial applications is due to the tremendous range of properties exhibited by plastics and their ease of processing. Plastic properties can be tailored to meet specific needs by varying the atomic makeup of the repeat structure; by varying molecular weight and molecular weight distribution; by varying flexibility as governed by presence of side chain branching, as well as the lengths and polarities of the side chains; and by tailoring the degree of crystallinity, the amount of orientation imparted to the plastic during processing and through copolymerization, blending with other plastics, and through modification with an enormous range of additives (fillers, fibers, plasticizers, stabilizers).
Most plastics contain organic polymers. The vast majority of these polymers are based on chains of carbon atoms alone or with oxygen, sulfur, or nitrogen as well. The backbone is that part of the chain on the main “path” linking a large number of repeat units together. To customize the properties of a plastic, different molecular groups “hang” from the backbone (usually they are “hung” as part of the monomers before the monomers are linked together to form the polymer chain). The structure of these “side chains” influences the properties of the polymer.
Most plastics contain other organic or inorganic compounds blended in. The amount of additives ranges from zero percentage for polymers used to wrap foods to more than 50% for certain electronic applications. The average content of additives is 20% by weight of the polymer.
Other classifications are based on qualities that are relevant for manufacturing or product design. Examples of such classes are the thermoplastic and thermoset, elastomer, structural, biodegradable, and electrically conductive. Plastics can also be classified by various physical properties, such as density, tensile strength, glass transition temperature, and resistance to various chemical products.
Natural vs. Synthetic
Most plastics are produced from petrochemicals. Motivated by the finiteness of petrochemical reserves and threat of global warming, bioplastics are being developed. Bioplastics are made substantially from renewable plant materials such as cellulose and starch.
Pure plastics have low toxicity due to their insolubility in water and because they are biochemically inert, due to a large molecular weight. Plastic products contain a variety of additives, some of which can be toxic.
For example, plasticizers like adipates and phthalates are often added to brittle plastics like polyvinyl chloride to make them pliable enough for use in food packaging, toys, and many other items. Traces of these compounds can leach out of the product. Owing to concerns over the effects of such leachates, the European Union has restricted the use of DEHP (di-2-ethylhexyl phthalate) and other phthalates in some applications. Some compounds leaching from polystyrene food containers have been proposed to interfere with hormone functions and are suspected human carcinogens. Other chemicals of potential concern include alkylphenols.
Plastics & Their Uses
Due to their relatively low cost, ease of manufacture, versatility, and imperviousness to water, plastics are used in an enormous and expanding range of products, from paper clips to spaceships. They have already displaced many traditional materials, such as wood, stone, horn and bone, leather, paper, metal, glass, and ceramic, in most of their former uses.
In developed countries, about a third of plastic is used in packaging and another third in buildings such as piping used in plumbing or vinyl siding.
A thermoplastic, or thermosoftening plastic, is a polymer that becomes pliable or moldable above a specific temperature, and returns to a solid state upon cooling. Most thermoplastics have a high molecular weight. The polymer chains associate through intermolecular forces, which permits thermoplastics to be remolded because the intermolecular interactions increase upon cooling and restore the bulk properties.
Various ‘Thermoforming’ processes have been developed for changing the shape of thermoplastic sheets by exploiting this property , including: Line Bending, Vacuum Forming, Dip Coating, Dome Blowing, Blow Moulding, Rotational Moulding, Injection Moulding, Extrusion Unlike thermosets, no chemical change, or cross linking of molecules, occurs during heating and cooling so that when a thermoformed object is re-heated, it will soften again and can be re-formed or left to return to its original shape.
Different types of Thermoplastic polymers are:
Acrylic, a polymer called poly(methyl methacrylate) (PMMA), is also known by trade names such as Lucite, Perspex and Plexiglas. It serves as a sturdy substitute for glass for such items as aquariums, motorcycle helmet visors, aircraft windows, viewing ports of submersibles, and lenses of exterior lights of automobiles. It is extensively used to make signs, including lettering and logos. In medicine, it is used in bone cement and to replace eye lenses. Acrylic paint consists of PMMA particles suspended in water.
Nylon, belonging to a class of polymers called polyamides, has served as a substitute for silk in products such as parachutes, flak vests and women’s stockings. Nylon fibers are useful in making fabrics, rope, carpets and strings for musical instruments. In bulk form, nylon is used for mechanical parts, including machine screws, gear wheels and power tool casings. In addition, nylon is used in the manufacture of heat-resistant composite materials.
The type of nylon (nylon 6, nylon 10, etc.) is indicative of the number of carbon atoms in the repeat unit. Many different types of nylons can be prepared, depending on the starting monomers used. The type of nylon is determined by the number of carbon atoms in the monomers used in the polymerization. The number of carbon atoms between the amide linkages also controls the properties of the polymer.
Low-density polyethylene (LDPE) is softer and flexible and is used in the manufacture of squeeze bottles, milk jug caps, retail store bags and (LLDPE) as stretch wrap in transporting and handling boxes of durable goods, and as the common household food covering. XLPE or “PEX” (cross-linked polyethylene) is a semi-rigid/flexible material which has gained wide use in cold or hot water building heating/cooling applications (hydronic heating and cooling) due to its exceptional resistance to breakdown from wide temperature variations.
Polypropylene (PP) is useful for such diverse products as reusable plastic food containers i.e. “microwave and dishwasher safe” plastic containers, diaper lining, sanitary pad lining and casing, ropes, carpets, plastic moldings, piping systems, car batteries, insulation for electrical cables and filters for gases and liquids. In medicine, it is used in hernia treatment and to make heat-resistant medical equipment.
Poly(vinyl chloride), commonly abbreviated PVC, is the third-most widely produced plastic, after polyethylene and polypropylene. PVC is a tough, lightweight material that is resistant to acids and bases. It is used in construction because it is more effective than traditional materials such as copper, iron or wood in pipe and profile applications. It is also converted to flexible forms with the addition of plasticizers, thereby making it useful for items such as hoses, tubing, electrical insulation, coats, jackets and upholstery.
POLYETHYLENE TEREPHTHALATE (PET OR PETE)
Polyethylene terephthalate also written as poly(ethylene terephthalate), commonly abbreviated PET, PETE, or the obsolete PETP or PET-P, or referred to by the brand name Dacron, is a thermoplastic polymer resin of the polyester family and is used in synthetic fibers; beverage, food and other liquid containers; thermoforming applications; and engineering resins often in combination with glass fiber.
Polyethylene terephthalate (PET or PETE) is a strong, stiff synthetic fiber and resin. PET is spun into fibers for permanent-press fabrics, blow-molded into disposable beverage bottles, and extruded into photographic film and magnetic recording tape. The term polyethylene terephthalate is a source of confusion because this substance, PET, does not contain polyethylene. Thus, the alternate form, poly(ethylene terephthalate), is often used for the sake of accuracy and clarity.
The majority of the world’s PET production is for synthetic fibers (in excess of 60%), with bottle production accounting for around 30% of global demand. In the context of textile applications, PET is referred to by its common name, “polyester,” whereas the acronym “PET” is generally used in relation to packaging. Polyester makes up about 18% of world polymer production and is the third-most-produced polymer; polyethylene (PE) and polypropylene (PP) are first and second, respectively. PET consists of polymerized units of the monomer ethylene terephthalate, with repeating C10H8O4 units. PET is commonly recycled, and has the number “1” as its recycling symbol.
The presence of a large aromatic ring in the PET repeating units gives the polymer notable stiffness and strength, especially when the polymer chains are aligned with one another in an orderly arrangement by drawing (stretching). In this semicrystalline form, PET is made into a high-strength textile fiber marketed under such trademarked names as Dacron, by the American DuPont Company, and Terylene, by the British Imperial Chemical Industries PLC.
Polyethylene terephthalate polyester (PETP) is a hard, stiff, strong, dimensionally stable material that absorbs very little water. It has good gas barrier properties and good chemical resistance except to alkalis (which hydrolyze it). Its crystallinity varies from amorphous to fairly high crystalline. Polyethylene terephthalate polyester (PETP) can be highly transparent and colorless but thicker sections are usually opaque and off-white.
The high strength of PET in comparison to its light weight is a major key to its energy efficiency, allowing for more products to be delivered in less packaging and using less fuel for transport. Ongoing advances in light-weighting technology continue to improve its energy efficiency even further. Life cycle studies of PET have consistently confirmed the environmental benefits of PET as a packaging material.
Polyethylene Terephthalate Films
Polyethylene terephthalate polyester (PETP) is widely known in the form of biaxially oriented and thermally stabilized films usually referred to by their main brand names Mylar, Melinex or Hostaphan. Strictly speaking, these names should be used only for this type of film whose properties are different from, and in several respects superior to, those of “ordinary” polyethylene terephthalate (PET) film.
A PET soft drink bottle
The longer the polymer chains the more entanglements between chains and therefore the higher the viscosity. The average chain length of a particular batch of resin can be controlled during polycondensation.
Drying of PET
The resulting cool wet air is then passed through a desiccant bed. Finally, the cool dry air leaving the desiccant bed is re-heated in a process heater and sent back through the same processes in a closed loop. Typically, residual moisture levels in the resin must be less than 50 parts per million (parts of water per million parts of resin, by weight) before processing. Dryer residence time should not be shorter than about four hours. This is because drying the material in less than 4 hours would require a temperature above 160 °C, at which level hydrolysis would begin inside the pellets before they could be dried out.
Such copolymers are advantageous for certain molding applications, such as thermoforming, which is used for example to make tray or blister packaging from co-PET film, or amorphous PET sheet (A-PET) or PETG sheet. On the other hand, crystallization is important in other applications where mechanical and dimensional stability are important, such as seat belts. For PET bottles, the use of small amounts of isophthalic acid, CHDM, DEG or other comonomers can be useful: if only small amounts of comonomers are used, crystallization is slowed but not prevented entirely. As a result, bottles are obtainable via stretch blow molding (“SBM”), which are both clear and crystalline enough to be an adequate barrier to aromas and even gases, such as carbon dioxide in carbonated beverages.
This is not such a problem for non-consumables (such as shampoo), for fruit juices (which already contain acetaldehyde), or for strong-tasting drinks like soft drinks. For bottled water, however, low acetaldehyde content is quite important, because, if nothing masks the aroma, even extremely low concentrations (10–20 parts per billion in the water) of acetaldehyde can produce an off-taste.
Commentary published in Environmental Health Perspectives in April 2010 suggested that PET might yield endocrine disruptors under conditions of common use and recommended research. Proposed mechanisms include leaching of phthalates as well as leaching of antimony.
Bottle Processing Equipment
There are two basic molding methods for PET bottles, one-step and two-step.
In two-step molding, two separate machines are used. The first machine injection molds the preform, which resembles a test tube, with the bottle-cap threads already molded into place. The body of the tube is significantly thicker, as it will be inflated into its final shape in the second step using stretch blow molding.
In the second step, the preforms are heated rapidly and then inflated against a two-part mold to form them into the final shape of the bottle. Preforms (uninflated bottles) are now also used as robust and unique containers themselves.
Propylene is a gaseous compound obtained by the thermal cracking of ethane, propane, butane, and the naphtha fraction of petroleum. Like ethylene, it belongs to the “lower olefins,” a class of hydrocarbons whose molecules contain a single pair of carbon atoms linked by a double bond. The chemical structure of the propylene molecule is CH2=CHCH3.
Under the action of polymerization catalysts, however, the double bond can be broken and thousands of propylene molecules linked together to form a chainlike polymer (a large, multiple-unit molecule). One of the important family of polyolefin resins, polypropylene is molded or extruded into many plastic products in which toughness, flexibility, light weight, and heat resistance are required.
Over time, plastics wear out from the repetitive stress of being opened and shut, and eventually will break. Polypropylene is very resistant to this sort of stress, and it is the plastic most often used for lids and caps that require a hinging mechanism.
A large proportion of polypropylene production is melt-spun into fibers. Polypropylene fiber is a major factor in home furnishings such as upholstery and indoor-outdoor carpets. Numerous industrial end uses exist as well, including rope and cordage, disposable nonwoven fabrics for diapers and medical applications, and nonwoven fabrics for ground stabilization and reinforcement in construction and road paving. These applications take advantage of the toughness, resilience, water resistance, and chemical inertness of the polymer.
An important concept in understanding the link between the structure of polypropylene and its properties is tacticity. The relative orientation of each methyl group (CH3 in the figure) relative to the methyl groups in neighboring monomer units has a strong effect on the polymer’s ability to form crystals.
Such isotactic macromolecules coil into a helical shape; these helices then line up next to one another to form the crystals that give commercial isotactic polypropylene many of its desirable properties.
Another type of metallocene catalysts produces syndiotactic polypropylene. These macromolecules also coil into helices (of a different type) and form crystalline materials.
When the methyl groups in a polypropylene chain exhibit no preferred orientation, the polymers are called atactic. Atactic polypropylene is an amorphous rubbery material. It can be produced commercially either with a special type of supported Ziegler-Natta catalyst or with some metallocene catalysts.
PP resins are defined as being semi-crystalline. Some of the molecular chains are able to pack relatively closely together and this leads to the formation of a limited amount of highly ordered crystalline areas.
In comparison, the molecular structures of certain other polymers commonly converted by injection molding or extrusion are much less ordered and as a consequence, they tend not to form crystalline areas. This group of polymers is defined as being amorphous.
Commercial grades usually contain around 97% of the isotactic variant, together with 3% of atactic and virtually none of the syndiotactic variant.
These figures can be varied somewhat by altering certain process parameters during the manufacture of the polypropylene, or alternatively by changing the catalyst.
The properties of polypropylene and the physical properties of the finished parts are controlled by a number of basic parameters:
Basic Types of PP
There are three basic PP types:
• Homopolymers (HOMO);
• Heterophasic Copolymers (HECO);
• Random Copolymers (RACO)
Presence of Selected Additives during Polymerization
However, dependent on the conversion process, the resultant dispersion of the additive may not be as good as that achieved by the above “fully-formulated” route and so some of the potential advantage may not be realized. This caveat is particularly relevant to high-speed injection molding.
Antioxidants and Stabilizers
As a family of polymers the polypropylene resins perform best when antioxidants and stabilizers are incorporated into their formulations in order to protect them against thermal degradation during conversion as well as permitting a long service life.
The presence of dust and dirt on the surface of any injection moulded article is undesirable, especially in the case of rigid packaging.
In many instances this layer is hydrophilic and so it attracts moisture from the air and it is this that acts as an electrostatically conductive medium and helps to dissipate any static charges, thereby limiting the formation of dust patterns.
Polymers’ PP grades used by customers for injection moulding are highly resistant to chemicals, essentially due to their hydrocarbon character and structure. Strong oxidizing acids have been reported to chemically attack, whilst some other substances may cause swelling, but most have little or no affect.
It is strongly recommended that expert advice is always sought before polypropylene is subjected to any chemical environment.
The sharpness of any notch is well-known to exert a strong influence on impact performance and a more reliable measure of the sensitivity may be obtained by determining notched impact strengths over a range of different notch-tip radii.
Polystyrene is one of the most widely used plastics, the scale of its production being several billion kilograms per year. Polystyrene can be naturally transparent, but can be colored with colorants.
Polystyrene is a “polymer of styrene.” Polymers are large molecules consisting of adjoined identical molecules, and styrene is a colorless, oily liquid. When polystyrene is made, its structure is that of a rigid transparent thermoplastic, resembling stiff white foam. It is one of the most common types of plastic, and it can be found in the home, in the office, at industrial sites, and just about any other place you would find plastics.
Plastic forks, DVD cases, the outside housing of computers, model cars, toys, rulers, and hair combs are all made from hard polystyrene. It is found frequently in the food industry and used as a disposable transportation system to keep hot and cold foods at desired temperatures. Disposable and reusable items can be made from polystyrene as it is cheap but durable.
In chemical terms, polystyrene is a long chain hydrocarbon wherein alternating carbon centers are attached to phenyl groups (the name given to the aromatic ring benzene). Polystyrene’s chemical formula is (C8H8)n; it contains the chemical elements carbon and hydrogen.
The ability of the system to be readily deformed above its glass transition temperature allows polystyrene (and thermoplastic polymers in general) to be readily softened and molded upon heating.
Extruded polystyrene is about as strong as an unalloyed aluminium, but much more flexible and much lighter (1.05 g/cm3 vs. 2.70 g/cm3 for aluminium).
Polystyrene results when styrene monomers interconnect. In the polymerization, the carbon-carbon pi bond (in the vinyl group) is broken and a new carbon-carbon single (sigma) bond is formed, attaching another styrene monomer to the chain. The newly formed sigma bond is much stronger than the pi bond that was broken, thus it is very difficult to depolymerize polystyrene. About a few thousand monomers typically comprise a chain of polystyrene, giving a molecular weight of 100,000–400,000.
A 3-D model would show that each of the chiral backbone carbons lies at the center of a tetrahedron, with its 4 bonds pointing toward the vertices. Consider that the -C-C- bonds rotated so that the backbone chain lies entirely in the plane of the diagram.
Properties of Polystyrene
Polystyrene is produced by the polymerization of the monomer styrene, which is a derivative of petroleum. If you look at the chemical structure of polystyrene, you’ll see that it is composed of carbon and hydrogen atoms only. Thus, it is classified as a hydrocarbon. Now, if you observe the bonds in its chemical structure, you’ll see that the carbon atoms are linked to one another by covalent bonds. Every alternate carbon atom on the polystyrene chain has a phenyl group (name given to benzene ring) attached to it. It is a long-chain hydrocarbon, and its chemical formula is C8H8)n.
Styrene is an aromatic monomer, commercially manufactured from petroleum. Polystyrene is a vinyl polymer, manufactured from the styrene monomer by free radical vinyl polymerization.
Strength, Durability, Comfort, Safety
Styrene is so widely used today because it enables a multitude of products to deliver many benefits that are highly valued by consumers. These benefits include strength, durability, comfort and safety. For example, styrene-based products cushion bicycle helmets, strengthen military armor, create wind power turbines, reduce coal plant emissions, enhance components that make cars and trains lighter and more fuel-efficient, enable manufacturing high-performance and cost-effective recreational products such as boats and other watercraft, and reduce dependence on costly natural resources such as tropical hardwoods used in boats and marble and granite used in homes and buildings.
Applications of PS
Eggs and dairy products, meat, fish and poultry, cold drinks or carry-out meals. All these products are safely packed with polystyrene packaging materials; by doing so spoilage of foods is prevented. In the western world a combination of good packaging, refrigeration and transportation ensures that only two percent of food is lost through spoilage, compared with 50 percent in developing countries.
From refrigerators and air conditioners, to ovens and microwaves, from hand-held vacuum cleaners to blenders, polystyrene resins meet almost all end-product requirements. Polystyrene resins are safe and cost effective, with excellent appearance and functionality mainly due to easy-processing. Because of this almost 26 percent of the polystyrene demand is used in injection-molding, extrusion and thermoforming applications.
Polystyrene is used for housing for TV’s and all kind of emerging trends in IT equipment where the critieria for use are combinations of function, form and aesthetics and a high performance/cost ratio. Polystyrene is the leading choice for media enclosures, cassette tape housing and clear jewel boxes to protect CD’s and DVD’s.
Polystyrene is very chemically inert, being resistant to acids and bases but is easily dissolved by d-limonene. Because of its resilience and inertness, it is used to fabricate many objects of commerce. It is attacked by many organic solvents, which dissolve the polymer. Foamed polystyrene is used for packaging chemicals.
Like all organic compounds, polystyrene burns to give carbon dioxide and water vapor. Polystyrene, being an aromatic hydrocarbon, typically combusts incompletely as indicated by the sooty flame.
If polystyrene is properly incinerated at high temperatures (up to 1000 °C) and with plenty of air (14 m3/kg), the chemicals generated are water, carbon dioxide, and possibly small amounts of residual halogen-compounds from flame-retardants. If only incomplete incineration is done, there will also be leftover carbon soot and a complex mixture of volatile compounds. According to the American Chemistry Council, when polystyrene is incinerated in modern facilities, the final volume is 1% of the starting volume; most of the polystyrene is converted into carbon dioxide, water vapor, and heat. Because of the amount of heat released, it is sometimes used as a power source for steam or electricity generation.
When polystyrene was burned at temperatures of 800–900 °C (the typical range of a modern incinerator), the products of combustion consisted of “a complex mixture of polycyclic aromatic hydrocarbons (PAHs) from alkyl benzenes to benzoperylene. Over 90 different compounds were identified in combustion effluents from polystyrene.”
Sheet or Molded Polystyrene
Polystyrene (PS) is used for producing disposable plastic cutlery and dinnerware, CD “jewel” cases, smoke detector housings, license plate frames, plastic model assembly kits, and many other objects where a rigid, economical plastic is desired. Production methods include thermoforming (vacuum forming) and injection molding.
Polystyrene Petri dishes and other laboratory containers such as test tubes and micro plates play an important role in biomedical research and science. For these uses, articles are almost always made by injection molding, and often sterilized post-molding, either by irradiation or by treatment with ethylene oxide. Post-mold surface modification, usually with oxygen-rich plasmas, is often done to introduce polar groups.
Expanded polystyrene (EPS) is a rigid and tough, closed-cell foam. It is usually white and made of pre-expanded polystyrene beads. EPS is used for disposable trays, plates, bowls and cups; and for carry-out food packaging (including the hinged lid containers popularly known as “clam shells”). Other uses include molded sheets for building insulation and packing material (“peanuts”) for cushioning fragile items inside boxes.
Adding fillers (graphite, aluminium, or carbons) has recently allowed the thermal conductivity of EPS to reach around 0.030–0.034 (as low as 0.029) and as such has a grey/black color which distinguishes it from standard EPS.
Fused Cell Expanded Polystyrene Foam
Pure polystyrene is brittle, but hard enough that a fairly high-performance product can be made by giving it some of the properties of a stretchier material, such as polybutadiene rubber.
Several other copolymers are also used with styrene. Acrylonitrile butadiene styrene or ABS plastic is similar to HIPS: a copolymer of acrylonitrile and styrene, toughened with polybutadiene. Most electronics cases are made of this form of polystyrene, as are many sewer pipes. SAN is a copolymer of styrene with acrylonitrile, and SMA one with maleic anhydride. Styrene can be copolymerized with other monomers; for example, divinylbenzene can be used for cross-linking the polystyrene chains to give the polymer used in Solid phase peptide synthesis.
Injection molding is a manufacturing process for producing parts by injecting material into a mold. Injection molding can be performed with a host of materials, including metals, glasses, elastomer, confections, and most commonly thermoplastic and thermosetting polymers. Material for the part is fed into a heated barrel, mixed, and forced into a mold cavity where it cools and hardens to the configuration of the cavity. After a product is designed, usually by an industrial designer or an engineer, molds are made by a mold maker (or toolmaker) from metal, usually either steel or aluminum, and precision-machined to form the features of the desired part. Injection molding is widely used for manufacturing a variety of parts, from the smallest components to entire body panels of cars.
Injection molding utilizes a ram or screw-type plunger to force molten plastic material into a mold cavity; this solidifies into a shape that has conformed to the contour of the mold. It is most commonly used to process both thermoplastic and thermosetting polymers, with the former being considerably more prolific in terms of annual material volumes processed.
Shot is the volume of material which is used to fill the mold cavity, compensate for shrinkage, and provide a cushion (approximately 10% of the total shot volume which remains in the barrel and prevents the screw from bottoming out) to transfer pressure from the screw to the mold cavity. When enough material has gathered, the material is forced at high pressure and velocity into the part forming cavity. Often injection times are well under 1 second. Once the screw reaches the transfer position the packing pressure is applied which completes mold filling and compensates for thermal shrinkage, which is quite high for thermoplastics relative to many other materials.
Parting line and ejector pin marks result from minute misalignments, wear, gaseous vents, clearances for adjacent parts in relative motion, and/or dimensional differences of the mating surfaces contacting the injected polymer. Dimensional differences can be attributed to non-uniform, pressure-induced deformation during injection, machining tolerances, and non-uniform thermal expansion and contraction of mold components, which experience rapid cycling during the injection, packing, cooling, and ejection phases of the process.
Examples of Polymers Best Suited for the Process
Most polymers, sometimes referred to as resins, may be used, including all thermoplastics, some thermosets, and some elastomers. The available materials are alloys or blends of previously developed materials meaning that product designers can choose from a vast selection of materials, one that has exactly the right properties.
This projected area is multiplied by a clamp force of from 1.8 to 7.2 tons for each square centimeter of the projected areas. As a rule of thumb, 4 or 5tons/in2 can be used for most products. If the plastic material is very stiff, it will require more injection pressure to fill the mold, thus more clamp tonnage to hold the mold closed.
Manufacturers go to great lengths to protect custom molds due to their high average costs. The perfect temperature and humidity level is maintained to ensure the longest possible lifespan for each custom mold. Custom molds, such as those used for rubber injection molding, are stored in temperature and humidity controlled environments to prevent warping.
Molds are built through two main methods: standard machining and EDM. Standard machining, in its conventional form, has historically been the method of building injection molds. With technological development, CNC machining became the predominant means of making more complex molds with more accurate mold details in less time than traditional methods.
EDM is a simple process in which a shaped electrode, usually made of copper or graphite, is very slowly lowered onto the mold surface (over a period of many hours), which is immersed in paraffin oil (kerosene). A voltage applied between tool and mold causes spark erosion of the mold surface in the inverse shape of the electrode.
The initial cost is great, however the per-piece cost is low, so with greater quantities the unit price decreases.
Rubber injection molding process produces a high yield of durable products, making it the most efficient and cost-effective method of molding. Consistent vulcanization processes involving precise temperature control significantly reduces all waste material.
What is Injection Molding Cycle?
Once the cavity is filled, a holding pressure is maintained to compensate for material shrinkage. In the next step, the screw turns, feeding the next shot to the front screw. This causes the screw to retract as the next shot is prepared.
The injection unit is responsible for both heating and injecting the material into the mold. The first part of this unit is the hopper, a large container into which the raw plastic is poured. The hopper has an open bottom, which allows the material to feed into the barrel. The barrel contains the mechanism for heating and injecting the material into the mold. This mechanism is usually a ram injector or a reciprocating screw. This increasing pressure allows the material to be packed and forcibly held in the mold.
Prior to the injection of the molten plastic into the mold, the two halves of the mold must first be securely closed by the clamping unit. When the mold is attached to the injection molding machine, each half is fixed to a large plate, called a platen.. An ejection system, which is attached to the rear half of the mold, is actuated by the ejector bar and pushes the solidified part out of the open cavity.
Injection molding machines are typically characterized by the tonnage of the clamp force they provide. The required clamp force is determined by the projected area of the parts in the mold and the pressure with which the material is injected. Therefore, a larger part will require a larger clamping force. Also, certain materials that require high injection pressures may require higher tonnage machines.
The injection molding process uses molds, typically made of steel or aluminum, as the custom tooling. The mold has many components, but can be split into two halves. Each half is attached inside the injection molding machine and the rear half is allowed to slide so that the mold can be opened and closed along the mold’s parting line.
In order for the molten plastic to flow into the mold cavities, several channels are integrated into the mold design. First, the molten plastic enters the mold through the sprue. Additional channels, called runners, carry the molten plastic from the sprue to all of the cavities that must be filled. At the end of each runner, the molten plastic enters the cavity through a gate which directs the flow. The molten plastic that solidifies inside these runners is attached to the part and must be separated after the part has been ejected from the mold.
In addition to runners and gates, there are many other design issues that must be considered in the design of the molds. Firstly, the mold must allow the molten plastic to flow easily into all of the cavities. Other devices enter through the end of the mold along the parting direction, such as internal core lifters, which can form an internal undercut. To mold threads into the part, an unscrewing device is needed, which can rotate out of the mold after the threads have been formed.
There are many types of materials that may be used in the injection molding process. Most polymers may be used, including all thermoplastics, some thermosets, and some elastomers. When these materials are used in the injection molding process, their raw form is usually small pellets or a fine powder. Also, colorants may be added in the process to control the color of the final part. The selection of a material for creating injection molded parts is not solely based upon the desired characteristics of the final part. Each material requires a different set of processing parameters in the injection molding process, including the injection temperature, injection pressure, mold temperature, ejection temperature, and cycle time.
Extrusion is the process by which long straight metal parts can be produced. The cross-sections that can be produced vary from solid round, rectangular, to L shapes, T shapes, tubes and many other different types. Extrusion is done by squeezing metal in a closed cavity through a tool, known as a die using either a mechanical or hydraulic press.
Single Screw Extrusion Machinery
There are numerous hardware considerations that can influence the quality of an extrusion. For example, screw geometry, screw rotation speed, and barrel heater temperature must be calibrated to suit the specific type of plastic being fabricated. Incompatible settings may hinder production or even damage the equipment.
The barrier screw is specifically designed with the transition section in mind. These screws have special barrier flights that improve mixing and melting by dividing the molten and solid plastic into separate channels. After the plastic is melted and compressed, it is channeled into the metering section. Here, the plastic undergoes pressurized pumping, while the root diameter of the screw and the flight size remain constant. Some extrusion screws use special mixing heads to homogenize the plastic before it travels into the next section.
The product assumes its final design inside the die. From the metering section, the plastic enters the front flange of the die, which is bolted onto the end of the extruder barrel. It flows around a metal parting tool, or “mandrel,” suspended in the center of the channel. At the rear of the mandrel, a pin and a land size the product. The pin and the land are both removable, making it relatively simple to reconfigure the die or to replace worn parts.
Pressurized air is introduced into one of the mandrel’s supports and exits from the die pin. This airflow prevents the product from collapsing as it leaves the die. Afterward, the component undergoes post-treatment.
Often screw length is referenced to its diameter as L:D ratio. For instance, a 6-inch (150 mm) diameter screw at 24:1 will be 144 inches (12 ft) long, and at 32:1 it is 192 inches (16 ft) long. An L:D ratio of 24:1 is common, but some machines go up to 32:1 for more mixing and more output at the same screw diameter. Two-stage (vented) screws are typically 36:1 to account for the two extra zones.
Cooling and Sizing Equipment
When the product leaves the die, it enters a vacuum chamber where it is pulled through sizing rings. The combination of vacuum pulling and air pressure forces the plastic to conform to the shape of the rings. If the sizing rings become worn, they leave behind longitudinal scoring on the product. The vacuum chamber is water-filled, which cools the plastic into a hard solid. The cooled product is then pulled by belted runners and is cut to length or coiled up onto a spool.
Advanced composite thermoplastics can also be compression molded with unidirectional tapes, woven fabrics, randomly oriented fiber mat or chopped strand.
The advantage of compression molding is its ability to mold large, fairly intricate parts. Also, it is one of the lowest cost molding methods compared with other methods such as transfer molding and injection molding; moreover it wastes relatively little material, giving it an advantage when working with expensive compounds. However, compression molding often provides poor product consistency and difficulty in controlling flashing, and it is not suitable for some types of parts. Fewer knit lines are produced and a smaller amount of fiber-length degradation is noticeable when compared to injection molding.
Compression molding was first developed to manufacture composite parts for metal replacement applications, compression molding is typically used to make larger flat or moderately curved parts. This method of molding is greatly used in manufacturing automotive parts such as hoods, fenders, scoops, spoilers, as well as smaller more intricate parts.
The compression molding starts, with an allotted amount of plastic or gelatin placed over or inserted into a mold. Afterward the material is heated to a pliable state in and by the mold. Shortly thereafter the hydraulic press compresses the pliable plastic against the mold, resulting in a perfectly molded piece, retaining the shape of the inside surface of the mold.
Blow molding is a molding process in which air pressure is used to inflate soft plastic into a mold cavity. It is a manufacturing process by which hollow plastic parts are formed such as bottles and similar containers. Since many of these items are used for consumer beverages for mass markets, production is typically organized for very high quantities. The technology is borrowed from the glass industry with which plastics compete in the disposable or recyclable bottle market.
Injection Blow Molding
The process of injection blow molding (IBM) is used for the production of hollow glass and plastic objects in large quantities. In the IBM process, the polymer is injection molded onto a core pin; then the core pin is rotated to a blow molding station to be inflated and cooled. This is the least-used of the three blow molding processes, and is typically used to make small medical and single serve bottles.
Injection Stretch Blow Molding Process
This has two main different methods, namely Single stage and two stage process. Single stage process is again broken down into 3 station and four station machines. In the two stage Injection stretch blow molding (ISB) process, the plastic is first molded into a “preform” using the injection molding process. These preforms are produced with the necks of the bottles, including threads (the “finish”) on one end..
Imagine the molecules are small round balls, when together they have large air gaps and small surface contact, by first stretching the molecules vertically then blowing to stretch horizontally the biaxial stretching makes the molecules a cross shape. These “crosses” fit together leaving little space as more surface area is contacted thus making the material less porous and increasing barrier strength against permeation.
What is PET Blow Moulding?
Blow molding or blow moulding is a manufacturing process by which hollow plastic parts are formed out of thermoplastic. Blow moulding is a process of inflating a hot, hollow, thermoplastic preform or parison inside a closed mold so its shape conforms to that of the mold cavity.
Blow molding is the third largest plastic processing technique behind injection molding and extrusion molding. Blow molding has the advantage that molded parts can be manufactured economically in unlimited quantities with little or practically no finishing operations.
Thermoforming is a manufacturing process where a plastic sheet is heated to a pliable forming temperature, formed to a specific shape in a mold, and trimmed to create a usable product. The sheet, or “film” when referring to thinner gauges and certain material types, is heated in an oven to a high-enough temperature that it can be stretched into or onto a mold and cooled to a finished shape.
It is a process in which a flat thermoplastic sheet is heated and deformed into the desired shape. The process is widely used in packaging of consumer products and to fabricate large items such as bathtubs, contoured skylights, and internal door liners for refrigerators.
In its simplest form, a small tabletop or lab size machine can be used to heat small cut sections of plastic sheet and stretch it over a mold using vacuum. This method is often used for sample and prototype parts. In complex and high-volume applications, very large production machines are utilized to heat and form the plastic sheet and trim the formed parts from the sheet in a continuous high-speed process, and can produce many thousands of finished parts per hour depending on the machine and mold size and the size of the parts being formed.
The earliest method was vacuum thermoforming (called simply vacuum forming when it was developed in the 1950s), in which negative pressure is used to draw a preheated sheet into a mold cavity. The process is explained below in its most basic form. The holes for drawing the vacuum in the mold are on the order of 0.8 mm (0.031 in.) in diameter, so their effect on the plastic surface is minor.
Vacuum forming is a simplified version of thermoforming, whereby a sheet of plastic is heated to a forming temperature, stretched onto or into a single-surface mold, and held against the mold by applying a vacuum between the mold surface and the sheet. The vacuum forming process can be used to make most product packaging and speaker casings.
An alternative to vacuum forming involves positive pressure to force the heated plastic into the mold cavity. This is called pressure thermoforming or blow forming its advantage over vacuum forming is that higher pressures can be developed because the latter is limited to a theoretical maximum of 1 atm.
Blow-forming pressures of 3 to 4 atm are common. The process sequence is similar to the previous, the difference being that the sheet is pressurized from above into the mold cavity. Vent holes are provided in the mold to exhaust the trapped air.
A way to improve the thinning distribution with a positive mold is to prestretch the sheet before draping it over the convex form. As shown in figure below, the heated plastic sheet is stretched uniformly by vacuum pressure into a spherical shape prior to drawing it over the mold.
The third method, called mechanical thermoforming, uses matching positive and negative molds that are brought together against the heated plastic sheet, forcing it to assume their shape. In the pure mechanical forming method, air pressure (positive or negative) is not used at all. The process is illustrated below. Its advantages are better dimensional control and the opportunity for surface detailing on both sides of the part. The disadvantage is that two mold halves are required; the molds for the other two methods are therefore less costly.
After a short form cycle, a burst of reverse air pressure is actuated from the vacuum side of the mold as the form tooling opens, commonly referred to as air-eject, to break the vacuum and assist the formed parts off of, or out of, the mold.
Thin Gauge and Heavy (Thick) Gauge Thermoforming
There are two general thermoforming process categories. Sheet thickness less than 1.5 mm (0.060 inches) is usually delivered to the thermoforming machine from rolls or from a sheet extruder. Thin-gauge roll-fed or inline extruded thermoforming applications are dominated by rigid or semi-rigid disposable packaging.
Heavy gauge parts are used as cosmetic surfaces on permanent structures such as kiosks, automobiles, trucks, medical equipment, material handling equipment, refrigerators, spas, and shower enclosures, and electrical and electronic equipment. Unlike most thin-gauge thermoformed parts, heavy-gauge parts are often hand-worked after forming for trimming to final shape or for additional drilling, cutting, or finishing, depending on the product.
Advantages of Thermoforming
The Thermoforming process has many advantages over other types of molding. Most commonly it is compared to the injection molding process as either process can be used for a large number of applications.
Thermoforming on the other hand utilizes a prototype tool made from wood or epoxy that can be used to create several finished parts of the product and formed from the same material as what the final product will be made from. Therefore many possible design or fit issues can be caught up front before going to production tooling, thus saving time and money.
When it comes to large parts, thermoforming wins hands down. From cost for both tooling and parts there is little comparison. A typical 45"x48" part for instance would have tooling at roughly half the cost of a comparable injection mold and the piece price is generally less as well, depending on material choice.
Pointing on disposable items is also quite easy and cheaper. The technology and machines are available in India and the cost is also less. This makes the disposable items more competitive and helps in increasing its market.
A plastic cup is a disposable cup made of plastic. It is most commonly used as a container to hold beverages. Plastic cups seem to be the best environmentally friendly option as most
Plastic glasses are made in factories and are usually mass-produced in order to lower the selling price. The raw plastic is brought to the factory where it is initially treated of dirt and other unwanted particles. This plastic is raw and needs to be chemically altered for it to become the viscous material required for producing the final product. Once the plastic is treated, the entire lot is put into a burner, where the heating process takes place. This process involves high temperatures and precision timing.
The process is also called vacuum forming since much of the early work was done using vacuum to furnish the forming pressure.
Thermoforming is a process in which temperature of the thermoplastic material is first raised and then the material is set to desired shape using several commercialized technique.
Material to be formed can be heated in a variety of ways, ranging from simple oven heating, oil baths and hot platens, upto complicated infrared heaters which heat one side or both side of the sheet at the same time. The higher heat ranges would of course be used for thicker material. The most important characteristic of the heating system is that the heat supplied be uniform, unless specifically required otherwise. In addition to being uniform, the heating equipment should be capable of heating the film or sheet in 15-40 records in order to be commercially useful.
There are a number of forming techniques in use, but all are basically variations of two simple processes in which the heated sheet is moved by (a) Air in the form of an applied vacuum and or pressurized and (b) Mechanical draw assists which force the sheet into the desired contour.
The last operation on the pat is trimming. Before dicing on the type of trimming operation, the extent of part shrinkage should be determined. It cools the pat will shrink in all directions. Most of the shrinkage will take place by the time the pat has reached room temperature however some shrinkage may continue to be noticed for 15-30 min after cooling.
Polypropylene/Polystyrene sheet feeding reels of preset length is dragged from bobbin reel in the thermoforming plant. The conveyor chains carry the sheet through the heater assembly to the forming table. The heated sheet is punched to form the shape of the mould. The cups thus formed are stocked and the punched waster sheet is wound on scrap sheet winder. To get printed cups, the sheets are printed before forming into cup. Taking 200ml. cup as yard stick as it is mostly used for serving coffee/tea the installed capacity of the machine with 5 cavities mould is approximately 52500 cups per shift. In terms of weight, a 200ml cup made of 0.7mm thick High Impact Polystyrene sheet is approximately 2.58 gms.
Printing on Cups, Glasses and Plates
Roto Gravure Printing
Gravure printing with copper or steel engraved plates is very ancient. In olden days, the pictorials or letterings were cut or etched into the face of rigid plate or copper or steed. The whole surface was then nicked and wiped clean so that the ink was only retained in the incised of engraved lines. Pressing paper against the ink plates did printing.
In a finished roto gravure print it is almost impossible to detect the halftones which show up clearly in letterpress, and that is why the process is well adapted to reproduction of shaded subjects. Because of the time required for plate preparation and relatively high initial costs, rotogravure is essentially a large-scale production process.
Plastic Cup thermoforming Machine
This machine is mainly used to form PP/PS/HIPS/PET/PVC sheet into various kinds of disposable cups, such as water/juice drinking cup, yoghurt cup, ice-cream cup, jelly cup, etc. It could also be used for making some regular shape container such as plate, dish, bowl, covers, etc. You could make different products with different moulds.
Take a Dia. =75mm, round cup
BABY DIAPER & SANITARY NAPKINS
A diaper is a kind of underwear that allows one to defecate or urinate in a discreet manner. When diapers become soiled, they require changing; this process is often performed by a second person such as a parent or caregiver.
Diapers are primarily worn by children who are not yet potty trained or experience bedwetting. However, they can also be used by adults with incontinence or in certain circumstances where access to a toilet is unavailable. These can include the elderly, those with a physical or mental disability, and people working in extreme conditions such asastronauts.
Basic layers are an outer shell of breathable polyethylene film or a nonwoven and film composite which prevents wetness and soil transfer, an inner absorbent layer of a mixture of cellulose pulp and superabsorbent polymers for wetness, and a layer nearest the skin of nonwoven material with a distribution layer directly beneath which transfers wetness to the absorbent layer.
Other common features of disposable diapers include one or more pairs of either adhesive or Velcro tapes to keep the diaper securely fastened. Some diapers have tapes, which are refastenable to allow adjusting of fit or reapplication following confirmation of an as yet unsoiled diaper. Elasticized fabric around the leg and waist areas aid in fitting and in containing urine or stool, which has not been absorbed.
Diapers these days as compare to the ones during mid 1990s, continue to become thinner and more absorbent. During the 1990s a modification of the SAP was developed. It uses a surface cross-linker to reduce the “gel block” problem: If the absorbent is saturated with a liquid, it prevents the liquid from moving.
Independent inventors also are continuing to modify the diaper. Marlene Sandberg of Stockholm has constructed a diaper that is 70 percent biodegradable. She uses corn-starch in the preparation of the outer layer of the diaper. This allows her to reduce the amount of polyacrylate used by designing channels in the fill material that help disperse the urine.
Types of Diapers
Modern disposable baby diapers and incontinence products have a layered construction, which allows the transfer and distribution of urine to an absorbent core structure where it is locked in.
Some diapers lines now commonly include wetness indicators, in which a chemical included in the fabric of the diaper changes color in the presence of moisture to alert the carer or user that the diaper is wet. A disposable diaper may also include an inner fabric designed to hold moisture against the skin for a brief period before absorption to alert a toilet training or bedwetting user that they have urinated.
Most materials in the diaper are held together with the use of a hot melt adhesive which is applied in spray form or multi lines, an elastic hot melt is also used to help with pad integrity when the diaper is wet. Some disposable diapers include fragrances, lotions or essential oils in order to help mask the scent of a soiled diaper or to protect the skin.
A sanitary napkin, sanitary towel, sanitary pad, menstrual pad, maxi pad, or pad is an absorbent item worn by a woman while she is menstruating, recovering from vaginal surgery, for lochia (post birth bleeding), abortion, or any other situation where it is necessary to absorb a flow of blood from a woman’s vagina.
Previously, in Japan, absorbent cotton was used for the purpose. But the use of absorbent cotton limited bodily movement considerably. Because of intensive improvement and progress of sanitary goods after World War II, sanitary napkin is replaced absorbent cotton in many countries today since it is clean & it can be carried easily, and since it is thrown away after once used.
Uses and Applications
1. Baby diapers are used for wrapping the newly born or pretty young children who have not get developed the fixed routine scheduled for making water or latrine.
2. Baby diapers are exclusively used by the modern society.
It has been already written before that this product is of great assistance for the caretaking & maintenance of pretty young & newly born babies who have no fixed routine schedule for maleing the water. They wet the clothes any time, which creates a lot of inconvenience to the mother or caretaker & they can’t go out of home with their babies.
Sanitary Napkins are exclusively used by adult girls & Ladies around the world during their menstrual periods as a means of maintaining physical aid & to avoid wetting or staining of the clothes.
1. Sanitary Napkin is not reasonable & it is to be thrown away only. When it is saturated with wet liquids.
2. Its use is much popular amongst the educated class of adult girls & ladies.
Advantages & Disadvantages of Disposable Diaper
As with all products, there are advantages and disadvantages to disposable diapers. The new polyacrylate gel has been linked to some side effects, including allergic reactions such as skin irritations, and to toxic shock syndrome. In addition, the dyes in the diapers have been linked to damage of the central nervous system, and disposable diapers may contain low concentrations of dioxin, a by-product of the bleaching process used in the production of the paper pulp found in the absorbent layer.
Disposable diapers are convenient, sanitary and easy to change. Through the use of absorbent materials and elastic portions added around the leg wrapping regions, these diapers provide effective containment of liquid and solid waste. Modern embodiments of disposable diaper frequently perform these tasks in a manner superior to that of traditional cloth diapers.
In general, disposable infant diapers include:
1. Vertically long body comprising a liquid permeable top sheet,
2. A liquid impermeable back sheet,
3. An absorbent member interposed there between,
Raw Materials for Manufacturing of Disposable Diaper
The single most important property of a diaper, cloth or disposable, is its ability to absorb and retain moisture. Cotton material used in cloth diapers is reasonably absorbent, but synthetic polymers far exceed the capacity of natural fibers. Today’s state-of-the-art disposable diaper will absorb 15 times its weight in water. This phenomenal absorption capacity is due to the absorbent pad found in the core of the diaper. These wood fibers act as thousands of tiny straws, which suck up water faster and disperse it through the matrix more efficiently to avoid gel blocking. Manufacturers have optimized the combinations of polymer and fibrous material to yield the most efficient absorbency possible.
The absorbent pad is at the core of the diaper. It is held in place by nonwoven fabric sheets that form the body of the diaper. Nonwoven fabrics are different from traditional fabrics because of the way they are made. Traditional fabrics are made by weaving together fibers of silk, cotton, polyester, wool, etc. to create an interlocking network of fiber loops. In this method the plastic resin is melted and extruded, or forced, through tiny holes by air pressure. As the air-blown stream of fibers cools, the fibers condense onto a sheet. Heated rollers are then used to flatten the fibers and bond them together. Polypropylene is typically the material used for the permeable top sheet, while polyethylene is the resin of choice for the non-permeable back sheet.
Surgical cotton rolls or cellulose fluff pulp and super-absorbent polymer for preparation of absorbent core.
Web lint tissue paper/spun lace non-woven the overstock or top sheet layer for wrapping the cotton lap cellulose fluff pulp in list tissue paper or non-woven spun lace and pasting.
A baby diaper is constructed by sandwiching a finely laid piece of cotton lap with or without absorbent polymer or cellulose fluff absorbed by cellulose fluff pulp and super absorbent polymer in between a lint tissue paper or nonwoven spunbond material as cover stock or top sheet and a fine quality polystyrene/polyethylene or spunbond nonwoven fabric sheet as back sheet.
Formation of the Absorbent Pad
The absorbent pad is formed on a movable conveyor belt that passes through a long “forming chamber.” At various points in the chamber, pressurized nozzles spray either polymer particles or fibrous material onto the conveyor surface. The bottom of the conveyor is perforated, and as the pad material is sprayed onto the belt, a vacuum is applied from below so that the fibers are pulled down to form a flat pad.
A second method of applying polymer and fiber involves application of the absorbent material onto the top surface of the pad after it has been formed. This method produces a pad, which has absorbent material, concentrated on its topside and does not have much absorbency throughout the pad. Another disadvantage is that a pad made in this way may lose some of the polymer applied to its surface.
These problems are solved by controlling the mixture polymer and fibrous material. Multiple spray dispensers are used to apply several layers of polymer and fiber. As the fiber is drawn into the chamber and the bottom of the pad is formed, a portion of the polymer is added to the mixture to form a layer of combined polymer and fiber. Then more pure fiber is pulled on top to give a sandwich effect. This formation creates a pad with the absorbent polymer confined to its center, surrounded by fibrous material
Mathematical Models for Disposable Diaper Manufacturing
The result is either a misuse of the materials or under-performance of the diaper. The fact of the matter is that even small changes in the core mix can result in significant changes in leakage performance. The correlation between diaper leakage and diaper cost is not linear; most of the times it is a polynomial equation. In order to be able to optimize the cost of the diaper for a given market segment, you need to understand the mathematical correlation between diaper performance and diaper cost.
Diaper production does not produce significant byproducts; in fact the diaper industry uses the byproducts of other industries. The absorbent polymers used in diaper production are often left over from production lines of other chemical industries. The polymer particles are too small for other applications, but they are well suited for use in diapers. However, this is not always possible due to clogging of filters and other losses.
Even more critical than this ratio are the size and distribution of these particles. It has been established that particles with mass medium particle size greater than or equal to about 400 microns work very well with the fibers to enhance the rate at which the fluid is transported away from the body. If the particles vary much outside this range, gel blocking may occur.
When the fabric is pulled off it may be left with a rough surface that is uncomfortable to the user. Finally, the alignment of the components must be carefully checked or leakage may result.
DISPOSABLE BANANA LEAF PLATE
In Central American countries, banana leaves are often used as wrappers for tamales.
Disposable cutlery and containers are products that are a part of our day-to-day life. Disposable items like cups, plates, saucers are being increasingly used. Such disposables items are made with natural materials like leaf as well as manmade products like paper, plastics. Leaf cups, plates have greater hygiene value. Cost-wise also it is cheaper than plastic and other plates. It has good demand in urban areas.
Banana leaf plate making is a state-of-the-art to develop biodegradable and compostable alternatives to petrochemical based plastics and polystyrene. From carrier bags to cling film, cutlery to cups, medical trays to plant pots, there is a crucial crusade against non-degradable plastics. A biodegradable product is one that’s broken down safely and relatively quickly by microbial activity into CO2, Water and Biomass – that’s bacteria, moulds and fungi: good stuff!
The length of time it takes for biodegradable products to break down can vary a lot. So claiming a product is biodegradable does not guarantee how quickly it will be reduced to these three constituents.
FACIAL TISSUE & BABY WET WIPES
Rolls are slitted according to size and dimension and then liquid detergent and other solvents are spread over the tissue paper to make wetting and then it make rolled form and pack it in the close pack with one side opening lid. Packing materials are made by using polymer resin and labeled by printed-paper. In the manufacturing process there is very negligible amount pollution obtained, which can be easily controlled. It has very good market demand.
What is a Tissue Paper?
Tissue paper or simply tissue is a lightweight paper or, light crêpe paper. Tissue can be made both from virgin and recycled paper pulp. Very exacting properties are generally required; for, though it is very light, it must be opaque, free of blemishes, pin holes, light spots and so on; and whether of the readily combustible variety or not, it must burn free of all objectionable odors.
Tissue paper is produced on a paper machine that has a single large steam heated drying cylinder (Yankee dryer) fitted with a hot air hood. The raw material is paper pulp. The Yankee cylinder is sprayed with adhesives to make the paper stick. The highest water absorbing applications are produced through air drying (TAD) process. These papers contain high amounts of NBSK (Northern bleached softwood Kraft) and CTMP (chemi-thermo-mechanical pulping processes). This gives a bulky paper with high wet tensile strength and good water holding capacity. The TAD process uses about twice the energy compared with conventional drying of paper.
The properties are controlled by pulp quality, creping and additives (both in base paper and as coating). The wet strength is often an important parameter for tissue paper.
Hygienic Tissue Paper
Hygienic tissue paper is commonly used for facial tissue (paper handkerchiefs), napkins, bathroom tissue and household towels. Paper has been used for hygiene purposes for centuries, but tissue paper as we know it today was not produced in USA before the mid-1940s. In Western Europe large scale industrial production started in the beginning of 1960s.
Facial tissue (paper handkerchiefs) refers to a class of soft, absorbent, disposable paper that is suitable for use on the face. The term is commonly used to refer to the type of facial tissue, usually sold in boxes, that is designed to facilitate the expulsion of nasal mucus from the nose although it may refer to other types of facial tissues including napkins and wipes.
Paper towels are the second largest application for tissue paper in the consumer sector. This type of paper has usually a basis weight of 20 to 24 g/m2. Normally such paper towels are two-ply. This kind of tissue can be made from 100% chemical pulp to 100% recycled fiber or a combination of the two. Normally, some long fiber chemical pulp is included to improve strength.
Facial tissue and paper handkerchief refers to a class of soft, absorbent, disposable papers that is suitable for use on the face. They are disposable alternatives for cloth handkerchiefs. The terms are commonly used to refer to the type of paper tissue, usually sold in boxes, that is designed to facilitate the expulsion of nasal mucus from the nose although it may refer to other types of facial tissues including napkins and wipes. Facial tissue is often referred to as a “tissue”, or by the generalized trademark ”Kleenex” which popularized the invention and its use.
Kleenex is a cleaner, healthier alternative to towels and handkerchiefs. The tissue paper might be treated with softeners, lotions or added perfume to get the right properties or feeling. Puffs facial tissues come with a splash of style and decorative boxes in assorted colors. Facial tissues are used in any home, restaurants, offices or hotels.
Manufacturing Process for Facial Tissues
Take tissue rolls in the strand and put it between the two revolved rolls in the opposite direction. By rotational movement tissue papers are moved forward over the supporting roll over which a spray nozzle adjustment by which liquid soap made from castor oil is sprayed slowly such that 5 gms. Liquid drops over the one square meter wide tissue paper. Afterwards it is pass through the pair of cold roll and then 5 gms, content 1%. Boric acid in it sprayed over one square meter tissue paper. Now these wetted tissue papers pass over the cold roll press. Now it is slitted according to width required and then slitted tissue papers wind up according to required length like 22 meters or any marketable required length.
Pulping and Retting
Soft tissue paper comes in varying thicknesses and textures but is mainly manufactured for facial tissue, bath tissue, paper towels, napkins and sometimes packing tissue. The first step in the process of making soft tissue paper is creating paper pulp, which can be generated from recycled materials or new ones.
The pulp is processed with a Yankee dryer, a drying cylinder heated by steam. This dryer puts the pulp through a process called creping; hence the term “crepe paper.” The hood above the roller dries the pulp with a forceful heat as the roller turns and a fine blade scrapes the tissue down to the soft, desired thickness. The tissue does not get completely scraped away, because the roller is first sprayed with adhesives.
A wet wipe, also known as a wet towel, or a moist towelette, is a small moistened piece of paper or cloth that often comes folded and individually wrapped for convenience. Wet wipes are used for cleaning purposes, like personal hygiene or household cleaning.
Paper cups available may be plain white or customized with prints or design on the sidewalls & cup-bottom using food grade ink. This light weight disposable cup is perfect for serving food items, as well as soups in religious ceremonies & many other occasions. Paper cups can be with & without handle sizes ranging from 3oz to 18oz.
Another popular type of paper cup is a long cylindrical type with a lid that fits on the top of the body and gives a perfect seal. They are very strong and used for packing all kinds of food products like Ice-cream dairy product etc. These cups are materially strong so that they can be reused. Paper cups are used for Ice cream as well as other products like dairy products, seafood, hot and cold beverages.
Wax coated paper cups are used cold foods and drink. Simple paper cups are used for hot food and made of paper with a low piece of paperboard at the piece. Paper cups are also made for drinking water only; their capacities are 100-200 ml. The sizes and shapes of these cups may vary.
Originally, paper cups for hot drinks were glued together and made waterproof by dropping a small amount of clay in the bottom of the cup, and then spinning at high speed so that clay would travel up the walls of the cup, making the paper water-resistant. However, this resulted in drinks smelling and tasting of cardboard.
Cups for cold drinks could not be treated in the same way, as condensation forms on the outside, then soaks into the board, making the cup unstable. To remedy this, cup manufacturers developed the technique of spraying both the inside and outside of the cup with wax. Clay-coated cups disappeared with the invention of polyethylene (PE) coated cups; this process covers the surface of the board with a very thin layer of PE, waterproofing the board and welding the seams together.
Printing on Paper Cups
Machines such as Comexi are used for this, which have been adapted to take the extra large reels that are required by paper cup manufacturers. Ink technology has also changed and where solvent-based inks were being used, water-based inks are instead being utilized.
One of the side effects of solvent-based inks is that hot drink cups in particular can smell of solvent, whereas water-based inks have eliminated this problem. Other methods of printing have been used for short runs such as offset printing, which can vary from anything from 10,000 to 100,000 cups. Offset printing inks have also been developed and although in the past these were solvent based, the latest soya-based inks have reduced the danger of cups smelling.
Most paper cups are designed for a single use and then disposal. Very little recycled paper is used to make paper cups because of contamination concerns and regulations. Because most paper cups are coated with plastic, both composting and recycling of paper cups is uncommon. Although paper cups are made from renewable resources (wood chips 95% by weight), paper products in a landfill may not decompose, or may release methane if decomposed anaerobically. The manufacture of paper usually requires inorganic chemicals and creates water effluents. Paper cups may consume more non-renewable resources than cups made of polystyrene foam (whose only significant effluent is pentane).
Paper vs. Plastic
A life cycle inventory of a comparison of paper vs. plastic cups shows environmental effects of both with no clear winner. PE is a petroleum based coating on paper cups that can slow down the process of biodegrading. Neither PE or PLA is completely biodegradable, and paper cups can only be recycled at a specialized treatment facility regardless of the lining.
A study of one paper coffee cup with sleeve (16 ounce) shows that the CO2 emissions is about 0.11 kilograms (.25 pounds) per cup with sleeve - including paper from trees, materials, production and shipping.
Paper cups may have various types of lids. The paper cups that are used as containers for yogurt, for example, generally have two types of lids: a press-on, re-sealable, lid (used for large “family size” containers, 250 ml to 1000 ml, where not all of the yogurt may be consumed at any one time and thus the ability to re-close the container is required) and heat-seal foil lids (used for small “single serving” containers, 150 ml to 200 ml).
Uses & Applications
The uses of paper cups have a wide range. Their applications leave a variety; they can be used for drinking water in cups made of plaited water. Wax-papered cups are used for keeping cold drinks, ice creams, fruit juices and other beverages. For coffee, tea and other hot drinks those un-waxed paper cups are applicable. Another special type of cylindrical paper cup is made which keeps hot and cold beverages like Ice creams and draft beer. For hot drink, paper cups used are provided with handles.
Polyethylene terephthalate (PET or PETE) is a strong, stiff synthetic fiber and resin, clear and lightweight, non-reactive, economical, and shatterproof plastic used around the world as an excellent energy-efficient packaging material. PET is spun into fibers for permanent-press fabrics, blow-molded into disposable beverage bottles, and extruded into photographic film and magnetic recording tape, personal care products, and many other consumer products. PET is the most recycled plastic worldwide. Bottles, jars and containers made of PET can be identified by the #1 “chasing arrows” recycling code stamped on the bottom.
To produce plastic bottles, the PET is first polymerized to create long molecular chains.
Polymerization itself can be a complicated process, and accounts for many of the inconsistencies between one batch of manufactured PET and another. Typically, two kinds of impurities are produced during polymerization: diethylene glycol and acetaldehyde. Although diethylene glycol is generally not produced in high-enough amounts to affect PET, acetaldehyde can not only be produced during polymerization, but also during the bottle manufacturing process. A large amount of acetaldehyde in PET used for bottle manufacturing can give the beverage inside an odd taste.
The mold must be cooled relatively quickly, so that that the newly formed component is set properly. There are several cooling methods, both direct and indirect, that can effectively cool the mold and the plastic. Water can be coursed through pipes surrounding the mold, which indirectly cools the mold and plastic. Direct methods include using pressurized air or carbon dioxide directly on the mold and plastic.
Once the bottle (or, in continuous manufacturing, bottles) has cooled and set, it is ready to be removed from the mold. If a continuous molding process has been used, the bottles will need to be separated by trimming the plastic in between them. If a non-continuous process has been used, sometimes excess plastic can seep through the mold during manufacturing and will require trimming. After removing the bottle from the mold and removing excess plastic, the bottles are ready for transportation.
The basic steps in the one-stage injection stretch blow process are:
Plasticizing the PET
Dried PET pellets are compressed and melted by a rotating screw.
Injection Molding the PET Preform
Molten PET is injected into the injection cavity and cooled rapidly to form a “preform? (The test-tube-like form from which bottles are blown is known as a preform).
THERMOCOL & ITS PRODUCTS
“Foam” is generally known everywhere but in fact its’ meaning is so wide. According to translation “Foam” means, “expand” or “blow”. Herewith we concern “Foam” as the expanded plastics. There are many kinds of plastics in the world, any plastics when react with the Blowing Agent will become “Foam” which generally called “Foam Plastics”.
The example of well -known foam plastics is sponge, food box, foam sheet, spray foam for insulation and etc. These foam plastics are produced from different kinds of plastics. The foam that produced from Polystyrene / PS (C8H8) plastic, PS Foam or so-called “Expanded Polystyrene” is made for food box, ice box, packaging for television and floating Krathong foam.
Thermocol contains an important thermoplastic compound, called polystyrene which is obtained by the polymerization of styrene or phenylethene. The chemical properties of phenylethene are identical to polyethene.
It responds very slowly to bacterial decomposition in the soil, thus making the soil infertile. It also releases poisonous gases on burning, which can cause respiratory problems, or even death, when inhaled. Hence thermocol is harmful for the environment.
It is fully resistant to all concentrated acid expect (HNO3 and H2SO4) but it is non resistant to aliphatic, hydrocarbons, ketones and chlorinated hydrocarbons and is affected by ultraviolet rays. It turns yellow and ultimate become brittle if left permanently exposed to sun.
Properties of Thermocol
Thermocol has been a material of choice for over half a century because of its technical versatility, performance and cost effectiveness. It is widely used in many everyday applications where its light weight, strength, durability, thermal insulation and shock absorption characteristics provide economic, high performance products.
Thermocol is an extremely lightweight material which is not surprising considering it is comprised of ~95% air. This characteristic makes it ideal for use in packaging as it does not significantly add to the weight of the total product thereby reducing transportation costs. Energy consumption for transport fuel is also reduced and vehicle emissions minimized – all contributing to lower global warming.
The exceptional durability of thermocol makes it an effective and reliable protective packaging for a wide range of goods. The cellular structure of thermocol makes it dimensionally stable and therefore does not deteriorate with age. Thermocol is also odorless and non-toxic.
Basic Raw Material Required
• Expanded Polystyrene Granule/beads
Basic Plant and Machinery Required
• Foam Sheet Extrusion Line
• Automatic Vacuum Forming Machine
• Double Worktables Hydraulic Cutting off Machine
• Recycling System
• The basic unit of polystyrene is styrene, which is the product of a two-fold reaction. Ethylene and benzene, in the presence of a catalyst such as aluminum chloride, form ethyl benzene (C8H8), which is then dehydrogenated (hydrogen is removed) at 1112-1202 degrees Fahrenheit (600-650 degrees Celsius) to form styrene (C8H8).
• Polystyrene is formed from styrene through suspension polymerization, a process by which tiny drops of the monomer (in this case, styrene) are completely surrounded by water and a mucilaginous substance. Supporting and surrounding the styrene globules, the suspension agent produces uniform droplets of polystyrene.
• Next, a polymerization initiator is added to the droplets, which are suspended by heat radiation of about 100 degrees Celsius. This results in free radicals, a group of atoms particularly likely to react with others because they contain unpaired electrons which are available for molecular bonding. Free radicals then combine at randomly to form chains of polystyrene.
• Stopping the polymerization process is difficult. Terminators are introduced to the process to end it at the appropriate time. Though variable, chain length must fall within a certain range, because polystyrene with overly long chains won’t melt readily, and polystyrene with short chains will be brittle.
Mostly used raw material is used engineered thermoplastic or special grade papers or wooden material or aluminum coated paper as raw material. Plenty of raw materials are available in India. Plant and machineries, which is required for manufacturing of the above mentioned products, are also available indigenously in our country. There are few technical experts available in this field that can provide total manufacturing process technology.
Disposable Plastic Cutlery Items
Basic Raw Material Used
1. Plastic Sheet like polypropylene, Polystyrene, P.V.C., H.D.P.E., L.L.D.P.E. etc.,
2. Di-butyl Phthalate.
Basic Plant and Machineries Required
1. Injection Moulding Machine
3. Conveyor Belt
4. Cooling Tower
Cutlery Packaging Machine
This machine adopts PLC intellectualized Micro-computer User-Interface Control Center, hence steady in performance with lower fault rate and easy to operate. Also the full set of steady electrical system can keep the machine with long time of working state,
Scope of Application
Suitable for the packing of products with irregular specification and multi-pieces or soft products such as medical pipette, sponge, ice-lolly, plastic fork, plastic scoop/spoon, mouth mask, towel, ice cream, popsicle/ice-lolly, woolen brush, glove, plastic tableware and toothbrush etc.
TOILET PAPER ROLLS
Toilet paper is a soft tissue paper product primarily used for the cleaning of the anus to remove fecal material after defecation or to remove remaining droplets of urine from the genitals after urination, and acts as a layer of protection for the hands during this process. It is typically sold as a long strip of perforated paper wrapped around a cardboard core, to be stored in a dispenser adjacent to a toilet.
For mass production, wood pulp of the raw material can be used to manufacture toilet paper but smaller mills use wood pulp and waste paper together or use waste paper and rags (Hosiery cutting, cotton linens etc), or waste paper 100 per cent.
Toilet paper is packed as 100 rolls in a case of corrugated board boxes for delivery to the primary under salary. Toilet paper is in large and increasing demand and its manufacturing can easily be embarked upon by small industry.
(1) Finished measured length 45,55,64, 75 mm.
(2) Substance of paper (crepes) 21 - 23 g/mm2.
(3) Out of the four lengths, the most popular in the market are 45 and 55 mm.
(4) Makers employee their respectively unique patterns on crepe.
Toilet paper is available in several types of paper, a variety of patterns, decorations, and textures, and it may be moistened or perfumed, although fragrances sometimes cause problems for users who are allergic to perfumes. The average measures of a modern roll of toilet paper is ~10 cm (3 15/16 in.) wide, 12 cm (4 23/32 in.) and weighs about 227 grams (8 oz.).
Toilet paper products vary greatly in the distinguishing technical factors: sizes, weights, roughness, softness, chemical residues, “finger-breakthrough” resistance, water-absorption, etc.
The larger companies have very detailed, scientific market surveys to determine which marketing sectors require/demand which of the many technical qualities. Modern toilet paper may have a light coating of aloe or lotion or wax worked into the paper to reduce roughness.
In order to advance decomposition of the paper in septic tanks or drainage, the paper used has shorter fibers than facial tissue or writing paper. The manufacturer tries to reach an optimal balance between rapid decomposition (which requires shorter fibers) and sturdiness (which requires longer fibers).
Color and Design
Colored toilet paper in colors such as pink, lavender, light blue, light green, purple, green, and light yellow (so that one could choose a color of toilet paper that matched or complemented the color of one’s bathroom) was commonly sold in the United States from the 1960s. Up until 2004, Scott was one of the last remaining U.S. manufacturers to still produce toilet paper in beige, blue, and pink.
Today, in the United States, plain un-patterned colored toilet paper has been mostly replaced by patterned toilet paper, normally white, with embossed decorative patterns or designs in various colors and different sizes depending on the brand. Colored toilet paper remains commonly available in some European countries.
1. Toilet paper can be used to remove make-up as it is cheaper than facial tissues.
2. Toilet papers are used in toilet.
Manufacturing Process for Toilet Paper Rolls
Tissue paper for toilet rolls place the tissue rolls in the strand and take out the start portion through the roll assemblies, slitter are attached to the rolls of 4"- 6" distances. Start the roll by motor driven power it will slit out at the distance of 4" - 6". Now slitted papers are stick with the core of winding strand. Start winding strand to roll out the tissue paper. There is electronic scanner adjusted for the previously adjusted length covers by rolling.