Flexible foams fabrication

Textile uses are a relatively stable area and consist of the lamination of polyester foams to textile products, usually by flame lamination or electronic heat sealing techniques. Flexible or semirigid foams are used in engineered packaging in the form of special slab material. Flexible foams are also used to make filters (reticulated foam), sponges, scmbbers, fabric softener carriers, squeegees, paint appHcators, and directly appHed foam carpet backing. 

National Emission Standards for Hazardous Air Pollutants Flexible Polyurethane Foam Fabrication Operations... 

Pollutants Flexible Polyurethane Foam Fabrication Operations... 

The furnishings market for flexible urethane foam can be divided into three major segments furniture, bedding, and carpet under-layment. These markets are supplied flexible foam by a larger number of firms known as the flexible slab foam industry which convert liquid chemicals to large foam buns made on a continuous conveyor. An infinite variety of cushion shapes are fabricated from the large foam buns. 

The polyether triols are the most important class of polyether polyols and they are used in flexible PU foam fabrication. The majority of polyether triols used in flexible foams are copolymers of PO-EO. Random copolymers are used in continuous slabstock flexible foams and block copolymers (PO-EO), with terminal poly[EO] block, are used in moulded foams (hot moulding and cold cure moulding processes). 

By using, together with a diol, a triol such as TMP or glycerol it is possible to obtain polyesters with a functionality (f) higher than 2 OH groups/mol, situated in the range of 2-3 OH groups/mol. These polyester polyols are used for flexible PU foam fabrication. Flexible PU foams based on polyester polyols have a unique property their clickability (capacity to be easily cut) and are used in laminates for textile industry. 

Chemical recovery processes by PU polymer breakdown through hydrolysis, glycolysis and aminolysis processes are extremely important because by using chemical reactions, the PU wastes are chemically transformed into new products which can possibly be used in the fabrication process of new PU. PU wastes are important raw materials for new polyols destined to become rigid and flexible foams. 

Glycolysis of flexible PU foams is also possible. At a ratio of PU waste DEG of 1-1.5 1, two layers are formed (the superior layer being rich in polyether), but at a higher ratio of 2-4 1 a homogeneous polyol mixture results, with an hydroxyl number of 360-390 mg KOH/g, which was used successfully in rigid PU foam fabrication [35]. 

Polynrethane (PU) was first synthesized in the 1930s by German chemist Otto Bayer (1902-1982), who was trying to prepare a nylonfike fiber. PU is a versatile polymer that is used for rigid and flexible foams, bristles, coatings, fibers, and automobile parts, such as bumpers. Other synthetics are nsed in products such as stretchable fabrics and binders for paints. 

Condit, D. A., D. Malek, A. D. Cianciolo, and C. H. Hofrichter. 1978. Life hazard evaluation of flexible polyurethane foam/fabric composites typical of cushioned upholstered furniture. 

Uses Functional polyol for coatings for fabrics and flexible foams Trade Names Lexorez 1721-65P... 

Solvent-based polyurethane adhesives find application particularly in the diverse field of product assembly operations, and are used for bonding materials such as steel, aluminium, timber products and rigid insulation. Products are available, however, that have been formulated to cure to a soft flexible adhesive film for bonding flexible materials such as fabrics and nylon scrim to flexible foams and sponge. 

The world production of polyurethane was about 16 billion pounds per year in 2010 to make PUR products in rubber, plastics, adhesives, sealants, fabrics, coatings, and both rigid and flexible foams. Over one-half of all polyurethane production goes into the manufacture of foam. Of that quantity, one-half is used to make flexible foam while the remainder is used to produce rigid foam. However, only about 800 million pounds of this production is used globally for high-performance rubber applications. 

PUs are widely used in the manufacture of flexible foam materials. In the textile industry, these polymers have been made into fibers with excellent elasticity. Spandex, which is a PU-based elastic fiber, has been incorporated into a wide range of textile fabrics, including elastic stockings for compression therapy. 

The later advent of more powerful catalysts, however, made it possible for straight PPC to be used in the preparation of flexible polyurethane foams (see one-shot processes in Chapter 1 of Plastics Fabrication and Recycling) without recourse to the foregoing procedures. Also, today the bulk of the polyethers used are triols rather than diols, since these lead to slightly cross-linked flexible foams with improved load-bearing characteristics. 

Preliminary research indicated that foams made of hollow bonded microspheres, approximately three millimeters in diameter, would be a desirable morphology given their closed-cell structure and flexibility of fabrication. These microspheres have been successfully fabricated using a process... 

Water-borne adhesives are preferred because of restrictions on the use of solvents. Low viscosity prepolymers are emulsified in water, followed by chain extension with water-soluble glycols or diamines. As cross-linker PMDI can be used, which has a shelf life of 5 to 6 h in water. Water-borne polyurethane coatings are used for vacuum forming of PVC sheeting to ABS shells in automotive interior door panels, for the lamination of ABS/PVC film to treated polypropylene foam for use in automotive instmment panels, as metal primers for steering wheels, in flexible packaging lamination, as shoe sole adhesive, and as tie coats for polyurethane-coated fabrics. PMDI is also used as a binder for reconstituted wood products and as a foundry core binder. 

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