Production of casein plastics

Casein plastics are today produced by the dry process . Although a wet process was used originally in Great Britain it has been obsolete for over 50 years and need not be discussed here. 

The resultant compound, in spite of the high water content, is a free-flowing powder. It should be processed soon after mixing since it will tend to putrefy. 

The extrudate is cut up into appropriate lengths and cooled by plunging into cold water. Subsequent operations depend on the end-product required. 

When rods are required they are placed in wooden trays in a formolising bath. If the requirement is for a disc or blank such as used by the button trade the extrudate is cut up by an automatic guillotine and the blanks are immersed in the formalin solution. For manufacture of sheets the rods are placed in moulds and pressed into sheets before formolising. Many attractive patterns may be made by pressing different coloured rods into grooves set on the bias to the rods, thus forming new multi-coloured rods. This operation may be repeated a number of times in order to produce complex patterns. 

The rod, blank or sheet must then be cured by a formolising process. They are immersed into a 4-5% solution of formaldehyde in water (formalin) for anything from two days to several months according to the thickness of the section. The formolising temperature is kept at about 16°C and the pH between four and seven. 

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Chemical nature Isolation of casein from milk Production of casein plastics Properties of casein Applications Miscellaneous Protein Plastics Derivatives of Natural Rubber Gutta Percha and Related Materials Shellac... 

Plastics materials may be produced from casein by plasticising with water, extrusion and then cross-linking with formaldehyde (formolisation). The resultant products have a pleasant horn-like texture and are useful for decorative purposes. The amount of casein produced has decreased since World War n but was still one of the preferred materials for use in the decorative button industry until quite recently. 

Of these materials zein, the maize protein, has been used for plastics on a small scale. It can be cross-linked by formaldehyde but curing times are very long. Complicated bleaching processes have led to the production of almost colourless samples in the laboratory but the process cannot readily be extended to large-scale operation. The cured product has a greater water resistance than casein. Proteins from soya bean, castor bean and blood have also been converted into plastic masses but each have the attendant dark colour. 

Commercial casein is usually manufactured from skim milk by precipitating the casein through acidification or rennet coagulation. Casein exists in milk as a calcium caseinate-calcium phosphate complex. When acid is added, the complex is dissociated, and at pH 4.6, the isoelectric point of casein, maximum precipitation occurs. Relatively little commercial casein is produced in the United States, but imports amounted to well over 150 million lb in 1981 (USDA 1981C). Casein is widely used in food products as a protein supplement. Industrial uses include paper coatings, glues, plastics and artificial fibers. Casein is typed according to the process used to precipitate it from milk, such as hydrochloric acid casein, sulfuric acid casein, lactic acid casein, coprecipitated casein, rennet casein, and low-viscosity casein. Differences... 

Use Production of polyurethane and unsaturated polyester resins, triethylene glycol textile softener petroleum solvent extraction dehydration of natural gas, plasticizers, and surfactants solvent for nitrocellulose and many dyes and oils humectant for tobacco, casein, synthetic sponges, paper products cork compositions, bookbinding adhesives, dyeing assistant, cosmetics, antifreeze solutions. 

The first plastic was a mixture of cellulose nitrate and camphor invented in the 1860s by John Wesley Hyatt it was given the TM Celluloid. In 1899 Spit-teler developed a method of hardening casein with formaldehyde and thus founded the casein plastics industry, e.g., small items such as buttons. The earliest high-volume plastic, a condensation product of phenol and formaldehyde, was introduced by Leo Baekeland in 1907. Trademarked Bakelite, it was the first truly synthetic high polymer. Its chief use was as engineering material since its dark color limited its application to items in which color was not a factor. 

Poly(ethylene glycol) is used to plasticize proteins, casein, gelatin, and poly(vinyl alcohol). Polyester plasticizers are condensation products of dicarboxylic acid with simple alcohols corresponding to the following two general formulas ... 

The first semisynthetic polymer, celluloid, was prepared by Alexander Parkes in 1855. Adolph Spitteler and W. Kirsch prepared plastic from milk protein (casein) and formaldehyde in 1899. Buttons, handles, pens and piano keys were made from the new material and it was patented under the name Galalith (aka Erinoid in the United Kingdom). Fully synthetic Bakehte was fist formulated by Leo Hendrik Baekeland (1863-1944) in 1907, and the age of plastics began with the discovery and large-scale industrial production of vulcanized rubber (1910), PVC (1926), polystyrene (1931), synthetic robber (1931-1935), polyethylene (1933), nylon... 

Plastics. Journal for the manufacture and application of processed or chemically fabricated materials with special consideration of artificial silk and other man-made fibers, of vulcanized, devulcanized (reclaimed) and synthetic caoutchouc, guttapercha etc. as well as substitute materials, of celluloid and similar cellulose products, of man-made leather and leather fabrics (linoleum), of resins, casein products etc. 

Substances of organic origin, such as wood flour, used for consumption products and in the production of electrical insulation cellulosic fibers (textiles, paper fibers and particles) used mainly to increase impact resistance fruit shell flour, which increases the fluidity of plastic materials under pressing and enhances the dielectric properties and appearance of final products protein flour—casein and soya flours for example—used with carbamides. 

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