Superabsorbent plastic

SAP superabsorbent plastic SGMP statistical good manufacturing practices... 

Acrylic acid and its salts are raw materials for an important range of esters, including methyl, ethyl, butyl, and 2-ethylhexyl acrylates. The acid and its esters are used in polyacrylic acid and salts (32%, including superabsorbent polymers, detergents, water treatment chemicals, and dispersants), surface coatings (18%), adhesives and sealants (15%), textiles and non-wovens (12%), plastic modifiers (5%), and paper coating (3%). 

There is a growing concern about fully biodegradable plastic — packing and wrapping foils, containers, equipment of fast-food restaurants, and superabsorbents. 

Superabsorbent polymers are used as a liquid-absorber in food packaging systems. In these systems, the superabsorbent polymers absorb juice or water from fresh foods such as raw chicken, shellfish, and other meats or from frozen foods as they thaw. Chilled superabsorbent polymer gels may also be used as a dry-cooling medium. The water-swollen gel, contained in a durable plastic bag, is frozen and used to keep perishable foods cold. In addition to its liquid-water-absorption characteristic, superabsorbent polymers absorb water from the vapor state and therefore may be used to control humidity. 

Starch from surplus corn has been converted into a superabsorbent material known as SUPER SLURPER. This is being marketed under license by several companies for use in removing water from refined petroleum products and as an absorbent in bandages and diapers. Biodegradable plastic films of starch mixed with other polymers find application as mulches in agriculture and as a... 

MAJOR USES Manufacture of other chemicals including acrylic esters, acrylic resins, superabsorbent polymers and detergents oil treatment chemicals, water treatment chemicals and water abosorbent polyacrylic acid polymers polishes, paints, coatings, rug backings, adhesives and plastics. 

In the early 1990s, composting and recycling of disposable diapers were actively considered in the United States, Canada and Europe. For composting, a biodegradable component such as pulp and superabsorbent polymer are used after removing the plastic back panel and tape. The compost has excellent water retention and can be used for soil improvement. Techniques to remove those plastics are now under development. 

With regard to recycling, Knowaste Technologies, Inc. of Canada is investigating a process [20] in which three materials, the pulp, plastics, and superabsorbent polymer, are recovered after washing, sterilization, separation, and drying. The recycled plastics can be used for industrial oilabsorbing resins, the pulp and paper can be used for toilet paper or sanitary products, and the superabsorbent polymer can be used for water-retention material in horticulture. 

Superabsorbent polymer sheets have also been developed. If a particulate superabsorbent polymer is crosslinked between particles by a cationic polymer, for example, an amine-epichlorohydrin adduct, a superabsorbent polymer sheet can be prepared [23]. A particulate superabsorbent polymer, cellulose acetate and a plasticizer are dispersed in an appropriate solvent followed by casting onto a nonwoven cloth substrate. Upon irradiation by ultrasound, a superabsorbent sheet can also be prepared [24]. However, such material has poor compatibility with blood and lacks capillary channels. Thus, further improvement is necessary. Accordingly, various new superabsorbent polymers have been developed. Unfortunately, these polymers show insufficient property improvement or are too costly to be commercially available. 

The sealed construction method is used to construct a horizontal tunnel. This method creates a great deal of soil, and depending upon the digging method used, this soil might be pasty and very heavy, which makes it difficult to move by truck. Hence it is necessary to modify the soil properties. One method employs superabsorbent polymers. In the following, plasticization of soil paste in a sealed constmction method will be introduced. 

The wraparound tape is made of a substrate sheet, such as a plastic film or nonwoven cloth, on which a superabsorbent polymer is coated. The superabsorbent polymer powder is mixed with an adhesive material, such as an organic polymer binder or a water-soluble resin, and coated onto the sheet. The sheet is then dried, fixed, and cut into strips. When the tape is in contact with water, the superabsorbent polymer particles absorb the water, swell, and become large hydrogel particles to prevent water penetration. 

As the substrate sheet, a thin plastic film or tightly packed nonwoven cloth, such as polyester spanbond nonwoven cloth of approximately 0.15 mm, is used. A synthetic rubber, such as styrene-butadiene rubber or thermoplastic polyurethane elastomer, is used as a binder. In addition, a surfactant for hydrophilicity, an antioxidant for prevention of thermodeformation, and a silica-type inorganic filler for prevention of tackiness are used. For the superabsorbent polymer particles, various synthetic polymers, for example, polyacrylate and polyvinyl-type superabsorbent polymers, can be used. For this apphcation, the particle sizes are an important parameter, because they polymer is required to be within the coating layer, and as the absorption rate is no retarded, quickly protrude from the layer when swelling. 

---