64-647: Artificial leather , also called synthetic leather , is a material intended to substitute for leather in upholstery, clothing, footwear, and other uses where a leather-like finish is desired but the actual material is cost prohibitive or unsuitable due to practical or ethical concerns. Artificial leather is known under many names, including leatherette , imitation leather , faux leather , vegan leather , PU leather ( polyurethane ), and pleather . Artificial leathers are often used in clothing fabrics, furniture upholstery, water craft upholstery, and automotive interiors. One of its primary advantages, especially in cars,
128-523: A coloring operation. Chemicals added during crusting must be fixed in place. Crusting culminates with a drying and softening operation, and may include splitting, shaving, dyeing , whitening or other methods. For some leathers, tanners apply a surface coating, called "finishing". Finishing operations can include oiling, brushing, buffing, coating, polishing, embossing, glazing , or tumbling , among others. Leather can be oiled to improve its water resistance. This currying process after tanning supplements
192-471: A highly negative charge so that they repel each other. Polycarboxylate ether superplasticizer (PCE) or just polycarboxylate (PC), work differently from sulfonate-based superplasticizers, giving cement dispersion by steric stabilisation. This form of dispersion is more powerful in its effect and gives improved workability retention to the cementitious mix. Plasticizers can be added to wallboard stucco mixtures to improve workability. In order to reduce
256-410: A mixture of nitrocellulose , camphor oil, alcohol, and pigment, embossed to look like leather. It was used as a bookbinding material and upholstery covering, especially for the interiors of motor vehicles and the interiors of railway carriages produced by British manufacturers beginning in the 1920s, its cost being around a quarter that of leather. Poromerics are made from a plastic coating (usually
320-417: A non-woven microfibre backing is a popular choice for clothing, and is comfortable to wear. Many different methods for the manufacture of imitation leathers have been developed. A current method is to use an embossed release paper known as casting paper as a form for the surface finish, often mimicking the texture of top-grain leather. This embossed release paper holds the final texture in negative. For
384-501: A number of properties including improved workability and strength. The strength of concrete is inversely proportional to the amount of water added, i.e., the water-cement (w/c) ratio. In order to produce stronger concrete, less water is added (without "starving" the mix), which makes the concrete mixture less workable and difficult to mix, necessitating the use of plasticizers, water reducers, superplasticizers, fluidizer or dispersants. Plasticizers are also often used when pozzolanic ash
448-520: A polymer chain is more complex in the presence of plasticizer than what the Flory–Fox equation predicts for a simple polymer chain. The molecules of plasticizer take control over mobility of the chain - a polymer chain does not show an increase of the free volume around polymer ends. If plasticizer/water creates hydrogen bonds with hydrophilic parts of the polymer, the associated free volume can be decreased. The effect of plasticizers on elastic modulus
512-572: A polyurethane) on a fibrous base layer (typically a polyester ). The term poromeric was coined by DuPont as a derivative of the terms porous and polymeric . The first poromeric material was DuPont's Corfam, introduced in 1963 at the Chicago Shoe Show. Corfam was the centerpiece of the DuPont pavilion at the 1964 New York World's Fair in New York City. After spending millions of dollars marketing
576-623: A properly managed facility. A review of the total pollution load decrease achievable according to the United Nations Industrial Development Organization posts precise data on the abatement achievable through industrially proven low-waste advanced methods, while noting, "even though the chrome pollution load can be decreased by 94% on introducing advanced technologies, the minimum residual load 0.15 kg/t raw hide can still cause difficulties when using landfills and composting sludge from wastewater treatment on account of
640-448: A retarding effect. Plasticizers are commonly manufactured from lignosulfonates , a by-product from the paper industry . Superplasticizers have generally been manufactured from sulfonated naphthalene condensate or sulfonated melamine formaldehyde , although newer products based on polycarboxylic ethers are now available. Traditional lignosulfonate-based plasticisers, naphthalene and melamine sulfonate-based superplasticisers disperse
704-585: A rubber formulation for a particular application. Plasticizers used in PVC and other plastics are often based on esters of polycarboxylic acids with linear or branched aliphatic alcohols of moderate chain length. These compounds are selected on the basis of many critieria including low toxicity, compatibility with the host material, nonvolatility, and expense. Phthalate esters of straight-chain and branched-chain alkyl alcohols meet these specifications and are common plasticizers. Ortho-phthalate esters have traditionally been
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#1732884043542768-645: A study by the FILK Freiberg Institute. Leather Leather is a strong, flexible and durable material obtained from the tanning , or chemical treatment, of animal skins and hides to prevent decay. The most common leathers come from cattle , sheep , goats, equine animals, buffalo, pigs and hogs, and aquatic animals such as seals and alligators. Leather can be used to make a variety of items, including clothing, footwear, handbags, furniture, tools and sports equipment, and lasts for decades. Leather making has been practiced for more than 7,000 years and
832-628: A wet cloth or soaking the leather in water. Various treatments are available such as conditioners . Saddle soap is used for cleaning, conditioning, and softening leather. Leather shoes are widely conditioned with shoe polish . Due to its high resistance to abrasion and wind, leather found a use in rugged occupations. The enduring image of a cowboy in leather chaps gave way to the leather-jacketed and leather-helmeted aviator . When motorcycles were invented, some riders took to wearing heavy leather jackets to protect from road rash and wind blast; some also wear chaps or full leather pants to protect
896-501: Is a natural-fiber alternative made from the bark of cork oak trees that has been compressed, similar to Presstoff. The production of the PVC used in the production of many artificial leathers requires a plasticizer called a phthalate to make it flexible and soft. PVC requires petroleum and large amounts of energy thus making it reliant on fossil fuels . During the production process carcinogenic byproducts, dioxins , are produced which are toxic to humans and animals. Dioxins remain in
960-448: Is a substance that is added to a material to make it softer and more flexible, to increase its plasticity , to decrease its viscosity , and/or to decrease friction during its handling in manufacture. Plasticizers are commonly added to polymers and plastics such as PVC , either to facilitate the handling of the raw material during fabrication, or to meet the demands of the end product's application. Plasticizers are especially key to
1024-440: Is added to concrete to improve strength. This method of mix proportioning is especially popular when producing high-strength concrete and fiber-reinforced concrete. Adding 1-2% plasticizer per unit weight of cement is usually sufficient. Adding an excessive amount of plasticizer will result in excessive segregation of concrete and is not advisable. Depending on the particular chemical used, use of too much plasticizer may result in
1088-534: Is also used for falconry jesses, soccer footwear, (e.g. Adidas Copa Mundial ) and boxing speed bags. Although originally raised for their feathers in the 19th century, ostriches are now more popular for both meat and leather. Ostrich leather has a characteristic "goose bump" look because of the large follicles where the feathers grew. Different processes produce different finishes for many applications, including upholstery, footwear, automotive products, accessories, and clothing. In Thailand , stingray leather
1152-411: Is called bating. Lipases are used in the degreasing operation to hydrolyze fat particles embedded in the skin. Amylases are used to soften skin, to bring out the grain, and to impart strength and flexibility to the skin. These enzymes are rarely used. The natural fibers of leather break down with the passage of time. Acidic leathers are particularly vulnerable to red rot , which causes powdering of
1216-424: Is dependent on both temperature and plasticizer concentration. Below a certain concentration, referred to as the crossover concentration, a plasticizer can decrease the modulus of a material. The material's glass transition temperature will decrease, however, at all concentrations. In addition to a crossover concentration, a crossover temperature exists. Below the crossover temperature the plasticizer will also increase
1280-452: Is one of the most exploited reptile species in the world in the leather trade. However, it is not endangered and while monitored, trade is legal in most South American countries. Kangaroo leather is used to make items that must be strong and flexible. It is the material most commonly used in bullwhips . Some motorcyclists favor kangaroo leather for motorcycle leathers because of its light weight and abrasion resistance. Kangaroo leather
1344-465: Is that it requires little maintenance in comparison to leather, and does not crack or fade easily, though the surface of some artificial leathers may rub and wear off with time. Artificial leather made from polyurethane is washable, but varieties made from polyvinyl chloride (PVC) are not easily cleaned. Depending on the construction, the artificial leather may be porous and breathable, or may be impermeable and waterproof. Porous artificial leather with
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#17328840435421408-420: Is that raw hides dry out to form a hard, inflexible material that, when rewetted, will putrefy , while tanned material dries to a flexible form that does not become putrid when rewetted. Many tanning methods and materials exist. The typical process sees tanners load the hides into a drum and immerse them in a tank that contains the tanning "liquor". The hides soak while the drum slowly rotates about its axis, and
1472-545: Is used in wallets and belts. Stingray leather is tough and durable. The leather is often dyed black and covered with tiny round bumps in the natural pattern of the back ridge of an animal. These bumps are then usually dyed white to highlight the decoration. Stingray rawhide is also used as grips on Chinese swords, Scottish basket hilted swords, and Japanese katanas . Stingray leather is also used for high abrasion areas in motorcycle racing leathers (especially in gloves, where its high abrasion resistance helps prevent wear through in
1536-589: The 1970s and 80s) are well known for wearing leather clothing. Extreme metal bands (especially black metal bands) and Goth rock groups have extensive black leather clothing. Leather has become less common in the punk community over the last three decades, as there is opposition to the use of leather from punks who support animal rights . Many cars and trucks come with optional or standard leather or "leather faced" seating. In countries with significant populations of individuals observing religions which place restrictions on material choices, vendors typically clarify
1600-782: The 2017 volume was ~1.01 million metric tonnes and in Europe the figure was 1.35 million metric tonnes, split between various end-use applications with a chemical type trend moving to higher molecular weight (HMW) orthophthalates and alternative types following regulatory issues concerning lower molecular weight (LMW) orthophthalates. Almost 90% of polymer plasticizers, most commonly phthalate esters , are used in PVC , giving this material improved flexibility and durability. Other polymers which can contain high loadings of plasticizers include acrylates and cellulose -type plastics, such as cellulose acetate , nitrocellulose and cellulose acetate butyrate . It
1664-566: The core, preventing a stronger core. The sugars, chelating agents in lignosulfonates such as aldonic acids and extractive compounds are mainly responsible for set retardation. These low range water reducing dispersants are commonly manufactured from lignosulfonates , a by-product from the paper industry . High range superplasticizers (dispersants) have generally been manufactured from sulfonated naphthalene condensate, although polycarboxylic ethers represent more modern alternatives. Both of these high range water reducers are used at 1/2 to 1/3 of
1728-426: The energy consumed drying wallboard, less water is added, which makes the gypsum mixture very unworkable and difficult to mix, necessitating the use of plasticizers, water reducers, or dispersants. Some studies also show that too much lignosulfonate dispersant could result in a set-retarding effect. Data showed that amorphous crystal formations occurred that detracted from the mechanical needle-like crystal interaction in
1792-427: The environment long after PVC is manufactured. When PVC ends up in a landfill it does not decompose like genuine leather and can release dangerous chemicals into the water and soil. Polyurethane is currently more popular for use than PVC. The production of some artificial leathers requires plastic, with others, called plant-based leathers , only requiring plant-based materials; the inclusion of artificial materials in
1856-679: The event of an accident). For a given thickness, fish leather is typically much stronger due to its criss-crossed fibers. Leather produces some environmental impact, most notably due to: Estimates of the carbon footprint of bovine leather range from 65 to 150 kg of CO 2 equivalent per square meter of production. One ton of hide or skin generally produces 20 to 80 m of waste water, including chromium levels of 100–400 mg/L, sulfide levels of 200–800 mg/L, high levels of fat and other solid wastes, and notable pathogen contamination. Producers often add pesticides to protect hides during transport. With solid wastes representing up to 70% of
1920-422: The flocculated cement particles through a mechanism of electrostatic repulsion (see colloid ). In normal plasticisers, the active substances are adsorbed on to the cement particles, giving them a negative charge, which leads to repulsion between particles. Lignin , naphthalene, and melamine sulfonate superplasticisers are organic polymers. The long molecules wrap themselves around the cement particles, giving them
1984-452: The following grades: The term "genuine leather" does not describe a specific grade. The term often indicates split leather that has been extensively processed, and some sources describe it as synonymous with bicast leather, or made from multiple splits glued together and coated. In some countries, when it is the description on a product label the term means nothing more than "contains leather"; depending on jurisdiction, regulations limit
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2048-486: The gypsum particles, giving them a highly negative charge so that they repel each other. Energetic material pyrotechnic compositions , especially solid rocket propellants and smokeless powders for guns, often employ plasticizers to improve physical properties of the propellant binder or of the overall propellant, to provide a secondary fuel, and ideally, to improve specific energy yield (e.g. specific impulse , energy yield per gram of propellant, or similar indices) of
2112-447: The hide is prepared for tanning. Preparatory stages may include soaking, hair removal, liming , deliming , bating , bleaching , and pickling . Tanning is a process that stabilizes the proteins , particularly collagen , of the raw hide to increase the thermal, chemical and microbiological stability of the hides and skins, making it suitable for a wide variety of end applications. The principal difference between raw and tanned hides
2176-490: The leading producers of leather today are China and India. Critics of tanneries claim that they engage in unsustainable practices that pose health hazards to the people and the environment near them. The leather manufacturing process is divided into three fundamental subprocesses: preparatory stages, tanning, and crusting. A further subprocess, finishing, can be added into the leather process sequence, but not all leathers receive finishing. The preparatory stages are when
2240-440: The leather. Chemical damage can also occur from exposure to environmental factors, including ultraviolet light, ozone, acid from sulfurous and nitrous pollutants in the air, or through a chemical action following any treatment with tallow or oil compounds. Both oxidation and chemical damage occur faster at higher temperatures. There are few methods to maintain and clean leather goods properly such as using damp cloth and avoid using
2304-482: The lignosulfonate types. Traditional lignosulfonate and naphthalene sulfonate-based plasticisers disperse the flocculated gypsum particles through a mechanism of electrostatic repulsion (see Colloid ). In normal plasticisers, the active substances are adsorbed on to the gypsum particles, giving them a negative charge, which leads to repulsion between particles. Lignin and naphthalene sulfonate plasticizers are organic polymers. The long molecules wrap themselves around
2368-480: The lower body. Leather's flexibility allows it to be formed and shaped into balls and protective gear. Subsequently, many sports use equipment made with leather, such as baseball gloves and the ball used in cricket and gridiron football . Leather fetishism is the name popularly used to describe a fetishistic attraction to people wearing leather, or in certain cases, to the garments themselves. Many rock groups (particularly heavy metal and punk groups in
2432-556: The main chemical in real leather, is under development. Materials to make vegan leather can be derived from fungi, yeasts and bacterial strains using biotechnological processes. One of the earliest artificial leathers was Presstoff . Invented in 19th century Germany, it was made of specially layered and treated paper pulp. It gained its widest use in Germany during the Second World War in place of leather, which under wartime conditions
2496-549: The makeup of the smell do not find phthalates in appreciable amounts, likely due to their extremely low volatility and vapor pressure. Bio-based plasticizers have been investigated, such as glycerol triacetate (Triacetin) and acetyltributylcitrate . They are used in niche applications. Epoxidized soybean oil is used broadly as a secondary plasticizer in many vinyl applications. In the concrete technology, plasticizers and superplasticizers are also called high range water reducers. When added to concrete mixtures, they confer
2560-457: The manufacture, the release paper is coated with several layers of plastic e.g. PVC or polyurethane, possibly including a surface finish, a colour layer, a foam layer, an adhesive, a fabric layer, a reverse finish. Depending on the specific process, these layers may be wet or partially cured at the time of integration. The artificial leather is cured, then the release paper is removed and possibly reused. A fermentation method of making collagen ,
2624-536: The many elastomer applications such as tubing and hose products, flooring, wall-coverings, seals and gaskets, belts, wire and cable, and print rolls. Low to high polarity esters provide utility in a wide range of elastomers including nitrile , polychloroprene , EPDM , chlorinated polyethylene , and epichlorohydrin . Plasticizer-elastomer interaction is governed by many factors such as solubility parameter , molecular weight , and chemical structure. Compatibility and performance attributes are key factors in developing
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2688-708: The modulus. Over the last 60 years more than 30,000 different substances have been evaluated for their suitability as polymer plasticizers. Of these, only a small number – approximately 50 – are today in commercial use. Ester plasticizers are selected based upon cost-performance evaluation. The rubber compounder must evaluate ester plasticizers for compatibility, processibility, permanence and other performance properties. The wide variety of ester chemistries that are in production include sebacates , adipates , terephthalates , dibenzoates , glutarates , phthalates , azelates , and other specialty blends. This broad product line provides an array of performance benefits required for
2752-447: The most dominant plasticizers, but regulatory concerns have led to the move away from classified substances to non-classified which includes high molecular weight ortho-phthalates and other plasticisers, especially in Europe. Antiplasticizers are polymer additives that have effect opposite to those of plasticizers. They increase the modulus while decreasing the glass transition temperature. Substantial concerns have been expressed over
2816-400: The natural oils remaining in the leather itself, which can be washed out through repeated exposure to water. Frequent oiling of leather, with mink oil , neatsfoot oil , or a similar material keeps it supple and improves its lifespan dramatically. Tanning processes largely differ in which chemicals are used in the tanning liquor. Some common types include: In general, leather is produced in
2880-470: The product to shoe manufacturers, DuPont withdrew Corfam from the market in 1971 and sold the rights to a company in Poland . Leatherette is also made by covering a fabric base with a plastic. The fabric can be made of natural or synthetic fiber which is then covered with a soft polyvinyl chloride (PVC) layer. Leatherette is used in bookbinding and was common on the casings of 20th century cameras. Cork leather
2944-577: The production of artificial leathers notably raises sustainability issues. However, some reports state that the manufacture of artificial leather is still more sustainable than that of real leather, with the Environmental Profit & Loss, a sustainability report developed in 2018 by Kering, stating that the impact of vegan-leather production can be up to a third lower than real leather. Some artificial leathers may have traces of restricted substances, like paint ingredient butanone oxime , according to
3008-428: The propellant. An energetic plasticizer improves the physical properties of an energetic material while also increasing its specific energy yield. Energetic plasticizers are usually preferred to non-energetic plasticizers, especially for solid rocket propellants . Energetic plasticizers reduce the required mass of propellant, enabling a rocket vehicle to carry more payload or reach higher velocities than would otherwise be
3072-530: The regulations currently in force in some countries." In Kanpur , the self-proclaimed "Leather City of World"—with 10,000 tanneries as of 2011 and a city of three million on the banks of the Ganges —pollution levels were so high, that despite an industry crisis, the pollution control board decided to shut down 49 high-polluting tanneries out of 404 in July 2009. In 2003 for instance, the main tanneries' effluent disposal unit
3136-448: The safety of some polymer plasticizers, especially because some low molecular weight ortho-phthalates have been classified as potential endocrine disruptors with some developmental toxicity reported. Plasticizers can escape plastics due to migration and abrasion of the plastic since they are not bound to the polymer matrix. The " new car smell " is often attributed to plasticizers or their degradation products, however, multiple studies on
3200-468: The shell. It is prized for its mirror-like finish and anti-creasing properties. Lamb and deerskin are used for soft leather in more expensive apparel. Deerskin is widely used in work gloves and indoor shoes. Reptilian skins, such as alligator , crocodile, and snake , are noted for their distinct patterns that reflect the scales of their species. This has led to hunting and farming of these species in part for their skins. The Argentine black and white tegu
3264-537: The source of leather in their products. Such labeling helps facilitate religious observance, so, for example, a Muslim will not accidentally purchase pigskin or a Hindu can avoid cattleskin. Such taboos increase the demand for religiously neutral leathers such as ostrich and deer . Judaism forbids the comfort of wearing leather shoes on Yom Kippur , Tisha B'Av , and during mourning. Also, see Leather in Judaism , Teffilin and Torah Scroll . Jainism prohibits
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#17328840435423328-400: The surface and a change in consistency. Damage from red rot is aggravated by high temperatures and relative humidities. Although it is chemically irreversible, treatments can add handling strength and prevent disintegration of red rotted leather. Exposure to long periods of low relative humidities (below 40%) can cause leather to become desiccated, irreversibly changing the fibrous structure of
3392-438: The tanning liquor slowly penetrates through the full thickness of the hide. Once the process achieves even penetration, workers slowly raise the liquor's pH in a process called basification, which fixes the tanning material to the leather. The more tanning material fixed, the higher the leather's hydrothermal stability and shrinkage temperature resistance. Crusting is a process that thins and lubricates leather. It often includes
3456-440: The term's use in product labelling. Today, most leather is made of cattle (cow) hides, which constitute about 65% of all leather produced. Other animals that are used include sheep (about 13%), goats (about 11%), and pigs (about 10%). Obtaining accurate figures from around the world is difficult, especially for areas where the skin may be eaten. There are significant regional differences in leather production: i.e. goat leather
3520-431: The usability of polyvinyl chloride (PVC), the third most widely used plastic. In the absence of plasticizers, PVC is hard and brittle; with plasticizers, it is suitable for products such as vinyl siding , roofing , vinyl flooring , rain gutters , plumbing , and electric wire insulation/coating. Plasticizers are also often added to concrete formulations to make them more workable and fluid for pouring, thus allowing
3584-682: The use of leather, since it is obtained by killing animals. Many forms of artificial leather have been developed, usually involving polyurethane or vinyl coatings applied to a cloth backing. Many names and brands for such artificial leathers exist, including "pleather", a portmanteau of "plastic leather", and the brand name Naugahyde . Another alternative is cultured leather which is lab-grown using cell-culture methods, mushroom-based materials and gelatin-based textile made by upcycling meat industry waste. Leather made of fungi or mushroom-based materials are completely biodegradable. Plasticizer A plasticizer ( UK : plasticiser )
3648-421: The water contents to be reduced. Similarly, they are often added to clays , stucco , solid rocket fuel , and other pastes prior to molding and forming. For these applications, plasticizers largely overlap with dispersants . Plasticizers for polymers are either liquids with low volatility or solids. According to 2017 data, the total global market for plasticizers was 7.5 million metric tonnes. In North America
3712-457: The weekend of 8 April 2017 in the neighborhood. The higher cost associated with the treatment of effluents than to untreated effluent discharging leads to illegal dumping to save on costs. For instance, in Croatia in 2001, proper pollution abatement cost US$ 70–100 per ton of raw hides processed against $ 43/t for irresponsible behavior. In November 2009, one of Uganda's main leather making companies
3776-724: The wet weight of the original hides, the tanning process represents a considerable strain on water treatment installations. Leather biodegrades slowly—taking 25 to 40 years to decompose . However, vinyl and petrochemical-derived materials take 500 or more years to decompose. Tanning is especially polluting in countries where environmental regulations are lax, such as in India, the world's third-largest producer and exporter of leather. To give an example of an efficient pollution prevention system, chromium loads per produced tonne are generally abated from 8 kg to 1.5 kg. VOC emissions are typically reduced from 30 kg/t to 2 kg/t in
3840-544: Was caught directly dumping waste water into a wetland adjacent to Lake Victoria . Enzymes like proteases , lipases , and amylases have an important role in the soaking, dehairing, degreasing, and bating operations of leather manufacturing. Proteases are the most commonly used enzymes in leather production. The enzyme must not damage or dissolve collagen or keratin , but should hydrolyze casein , elastin , albumin , globulin -like proteins, and nonstructural proteins that are not essential for leather making. This process
3904-405: Was commonly thought that plasticizers work by embedding themselves between the chains of polymers , spacing them apart (increasing the "free volume"), or swelling them and thus significantly lowering the glass transition temperature for the plastic and making it softer. It was later shown that the free volume explanation could not account for all of the effects of plasticization. The mobility of
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#17328840435423968-576: Was dumping 22 tonnes of chromium-laden solid waste per day in the open. In the Hazaribagh neighborhood of Dhaka in Bangladesh , chemicals from tanneries end up in Dhaka's main river. Besides the environmental damage, the health of both local factory workers and the end consumer is also negatively affected. After approximately 15 years of ignoring high court rulings, the government shut down more than 100 tanneries
4032-496: Was historically called "Turkey" or "Morocco" due to its association with the Middle East, while pig skin had historically been used the most in Germany. Other animals mentioned below only constitute a fraction of a percent of total leather production. Horse hides are used to make particularly durable leathers. Shell cordovan is a horse leather made not from the outer skin but from an under layer, found only in equine species, called
4096-476: Was rationed. Presstoff could be used in almost every application normally filled by leather, excepting items like footwear that were repeatedly subjected to flex wear or moisture. Under these conditions, Presstoff tends to delaminate and lose cohesion. Another early example was Rexine , a leathercloth fabric produced in the United Kingdom by Rexine Ltd of Hyde, near Manchester. It was made of cloth surfaced with
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