Foam finishing techniques

The cotton fabrics were treated using conventional padding and foam-finishing techniques by United Merchants and Manufacturers. The two finishing agents used have the tradenames of Valrez 2i)8 and Valrez ULF. Valrez 2kB is dimethyloldihydroxyethyleneurea (DMDHEU) with the following structure ... 

In cases where either of these techniques would adversely affect the esthetics of the face of the fabric, the foamed finish can be applied to the back of the fabric by means of a floating knife. 

Soil retardants can be applied to fibers, yams, fabrics, or carpets by spraying, padding, kiss-roll, or foam application techniques. Some soil retardants are applicable also by exhaust methods. Spraying is the most popular method for applying soil retardants to carpets. The required amount of a soil-retardant product is typically 0.5-1.6% of the weight of dry face fiber or about 200 ppm as fluorine. Usually, the soil retardant as applied as the last step before the carpet is dried. The presence of a fluorinated finish on the carpet can be confirmed by an oil-repel-lency test, based on the AATCC 118-1997 test (see Chapter 12), or a water-repel-lency test. Fuorier transform infrared and x-ray photoelectron spectroscopy (ESCA) (Chapter 9) provide semiquantitative information on the fluorinated soil-retardant concentration on the fibers. 

Silicones and flnorocarbon polymers cannot easily be stripped off, especially when they are crosslinked. As it is the natnre of repellent finishes to reduce adhesion, there are problems with backcoating and laminating of fabrics finished by padding flnorochemicals. One solntion is the one side application of the repellents by nip-padding, spray, foam or sqneegee techniques. 

Furniture fabrics are back-coated with non-slip finishes, often with polymer-based ones. The formulation may include thickeners and flame retardants. Back-coating is mostly achieved by nip-padding or using a doctor (squeegee) or by foam application or spray techniques (for a lower add-on). Another one-side application is rotary printing (screens with regular perforation). 

Indicative of an all-encompassing approach is the development of the market in depth. The promotion of toluene diisocyanate furnishes an excellent example. The producers of this product as an element in foam have been forced to go all out in developing techniques of fabrication of the finished product, to demonstrate to the ultimate user of foam that systems containing TDI are indeed competitive with and superior to the existing foam (nonchemical) products. The technical service charges which result from such an endeavor loom large. Yet, without them, the chances of success were slim. 

In-mould coating should be mentioned here for completeness. This technique is widely used for integral skin foam components in PUR, principally in the passenger compartment. It is also used to prime SMC parts, as an aid to producing a Class A finish on the topcoat. The RTM methacrylic resin panels of the Alfa Romeo SZ were in-mould coated to a Class A finish. As this was a specialist vehicle and no other painted panels were involved, the usual problems of reduced production rate and poor colour matching did not apply. 

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