Carpet Backing Binders

Carpeting is produced in enormous quantities throughout the world. Carpeting is manufactured by sewing loops 

In 1975 it was estimated that one third of all the broadloom carpet produced in the USA had an attached SBR cushion. Unfortunately, the highly competitive situation prevailing at the time, compelled manufacturers to reduce the cost of the attached foam by either increasing the level of the cheap calcium carbonate filler and/or reducing foam application weights and density. This inevitably adversely affected the durability of the foam to such an extent that failure occurred resulting in premature wear of the carpet. As consequence of the bad name that attached SBR cushions obtained in the eyes of consumers, today HSL foam backed carpet has virtually disappeared in the USA, with the exception of a few specialty floor coverings such as bath mats. 

A similar situation to that observed in the USA has been experienced for similar reasons, but at a much slower speed. The consumption of HSL for foam backing remained fairly static for many years, the growth in the market being almost entirely restricted to secondary backed products, and the market share of foam backed carpet being gradually eroded. 

In the late nineteen-nineties environmental pressure, particularly in Germany, resulted in a very steep decline in the consumption of HSL for floor coverings. Several of the ingredients used in the formulations for HSL foam in the floor coverings industry were brought into ecological question. Since 1998, when foam backed carpets made up approximately 45 % of textile floor coverings in Europe, this has decreased to approximately 20 % in 2000. 

An alternative more ecologically friendly product was required. In Europe this was achieved by replacing the HSL foam by a needlefelt product which is adhered to the carpet by means of an XSB latex. In North America carpet underlays made of polyurethane foam are commonly used to provide the soft comfort of residential carpets. 

Over the years, it is fair to say that virtually every type of polymer available in dispersion form has been tried for use in the backing compound for tufted carpet. However, because of its versatility and cost-effectiveness, it is the carboxylated styrene-butadiene (XSB) polymer dispersions that hold the major share of this business today with an estimated 95 % of the volume sold in 1999, the remaining volume being shared by ethylene-vinyl acetate, polyvinyl chloride and polyurethane dispersions. During 1999, the U S carpet industry consumed approximately 490 kt wet dispersion, of which 463 kt were XSB [4]. The majority of the XSB is supplied direct to the carpet mills by the three major dispersion producers BASF, Dow Chemical, Omnova, with a minor proportion being supplied by so-called re-sellers or compounders such as General Latex, Polymer Products, Southeastern Latex and Textile Rubber. 

Initially starches and natural rubber latex were used as binders for improved tuft bind. They were replaced in the late 1950s by carboxylated styrene-butadiene dispersions (XSB). XSB emulsion polymers are very cost effective and easy to formulate, and they have become the working horse of the carpet backing industry and are almost exclusively used today. 

Carboxylated styrene-butadiene dispersions have a solids content of about 52%, a pH between 7.5 and 9.0, and a monomodal particle size distribution with an average diameter of about 150 nm. With this small particle size, the instantaneous conversion during emulsion polymerisation is high, which leads to low concentrations of by-products, such as 4-phenyl-cyclohexene (4-PCH) and 4-vinyl-cyclohexene (4-VCH) generated by Diel-Alder reaction of styrene and butadiene. 4-PCH and 4-VCH concentrations are required to be below certain limits, since they have a very low odour threshold. 

The polymer composition is typically about 65% styrene and less than 3% carboxylic acid, for example, acrylic or itaconic acid, the rest being butadiene. 

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The copolymer composition also affects the hydrophobicity (390) and flame retardancy of the latex product. Copolymerisation with the appropriate monomers can improve the water resistance or raise the flame retardancy in carpet backing binders and nonwovens. Copolymers may be incorporated in a wide range of ratios, such as 1% acrylic acid in surface functionalised polystyrene latexes, or at 50% in acrylic copolymer latexes. 

Vinylidene Chloride Copolymer Latex. Vinyhdene chloride polymers are often made in emulsion, but usuaUy are isolated, dried, and used as conventional resins. Stable latices have been prepared and can be used direcdy for coatings (171—176). The principal apphcations for these materials are as barrier coatings on paper products and, more recently, on plastic films. The heat-seal characteristics of VDC copolymer coatings are equaUy valuable in many apphcations. They are also used as binders for paints and nonwoven fabrics (177). The use of special VDC copolymer latices for barrier laminating adhesives is growing, and the use of vinyhdene chloride copolymers in flame-resistant carpet backing is weU known (178—181). VDC latices can also be used to coat poly(ethylene terephthalate) (PET) bottles to retain carbon dioxide (182). 

Vinyl acetate [108-05-4] (VAc), CH2=CHOOCCH2, the ethenyl ester of acetic acid, is primarily use for the manufacture of poly(vinyl acetate) [9003-20-7] (PVAc) and vinyl acetate copolymers. Poly(vinyl acetate) homo- and copolymers are found as components in coatings, paints and sealants, binders (adhesives, nonwovens, constmction products, and carpet-backing), and miscellaneous uses such as chewing gum and tablet coatings. AppHcations have grown over the years in a number of areas (1 4). 

Binder formulas for carpet backing, aluminum foil to paper, vinyl flooring, tire cord, paper labeling, masking tape, and oriented polypropylene tape applications are available from Midgley and Rea in Skiest [215]. 

A modified latex composition contains a phosphorus surface group. Such a latex is formed by emulsion polymerization of unsaturated synthetic monomers in the presence of a phosponate or a phosphate which is intimately bound to the surface of the latex. Thus, a modified latex containing 46% solids was prepared by emulsion polymerization of butadiene, styrene, acrylic acid-styrene seed latex, and a phosphonate comonomer in H20 in the presence of phosphated alkylphenol ethoxylate at 90°C. The modified latex is useful as a coating for substrates and as a binder in aqueous systems containing inorganic fillers employed in paper coatings, carpet backings, and wallboards [119]. 

Antistatic agents for carpet backing gives a complete antistatic carpet in combination with conductive pile material can be used in adhesives for secondary backing also, compatible with binders for needle felts. 

Use (Solid) Mechanical rubber products, lining oilloading hose and reaction equipment, adhesive cement, binder for rocket fuels, coatings for electric wiring, gaskets and seals. (Liquid) Specialty items made by dipping or electrophoresis from the latex. (Foam) Adhesive tape to replace metal fasteners for automotive accessories, seat cushions, carpet backing, sealant. 

It has been proved that incorporation of carboxylic acid groups in the polymeric chain has a significant effect on colloidal properties of latex, processability, and end-use property. Carboxylated styrene-butadiene latexes (XSBR) are prepared via batch emulsion copolymerization with different amounts of acrylic acid in the absence of emulsifier. They are among the most important polymeric colloids, and can be used as binder in paper coatings, carpet backing, paints, and nonwoven. There are several studies on the preparation and properties of XSBR latexes. 

Bayer SBR Latex. [Bayer] Styrene-butadiene latex for blended latex goods, paper impregnation, carpet backing, ne e felt ronfoicement binder. 

Uses Pigment dispersant for paints and aq. coatings based on polymeric binders (paper coatings, adhesives, carpet backings, plasters) Features Low foaming effective with hydrophilic pigments and extenders... 

Uses Flame retardant, plasticizer for PVC and other polymers, rubber, aq. systems, latexes based on PVC, SBR, PVAc, acrylics, EVA, paints, dyes, nonwoven fabric binders, textile back coatings, carpet backings, asbestos paper bindings, adhesives, pigment carriers Features Emulsifiable... 

Uses Used in mfg. of thermoplastic and cast elastomers, textile coatings, paints, stmctural foam, adhesives and binders, automotive parts, flexible foams for bedding/upholstery, rigid insulation foams, carpet backing... 

Glyceryl behenate Hydrogenated cottonseed oil Hydrogenated palm oil binder, carbon arc-light electrodes Potassium silicate binder, carpet backing Styrene/butadiene polymer binder, catalysts Silica, colloidal binder, caulks Vinyl acrylic copolymer binder, cement Polyacrylamide Sulfur binder, cementitious surfaces Potassium silicate binder, ceramic Ethylene/MA copolymer binder, ceramic fibers Silica, colloidal binder, ceramic glazes Hydroxyethylcellulose Methylcellulose binder, ceramic paste Ethyl silicate... 

Adhesives are widely used in the textile industry as shown in Table 1. If sizes and tyre cord dips are excluded, approximately 65% are used in carpet backing (mostly styrene-butadiene rubbers). Other major uses of adhesives are in non-wovens as binders (15%), in fabric backing (8%), in flocking and laminating (8%) and in fusible interlinings (2%). 

This paper reports on the synthesis, characterisation, and applications of novel flame retardant dibromostyrene-based latexes. They are copolymers of dibromostyrene with butadiene, alkyl acrylates and methacrylates, vinyl acetate, styrene and unsaturated carboxylic acids, which form a wide variety of flame retardant latexes via an emulsion polymerisation technique. Choice of monomer or monomer blend is based upon the final glass transition temperature of the copolymer desired. Other criteria include desired physical properties and chemical resistance. Dibromostyrene-based butadiene and acryUc latexes are shown to possess the desired physical properties for use in coatings, adhesives and sealants, and the bromine content of the latexes has enabled the material to pass six different flammability requirements for the end uses such as textile backcoating, latex-based paint, contact adhesive, latex sealant, nonwoven binder, and carpet backing. 18 refs. 

The BRIGS total market size, shown in Figure 2, represents 24% (6.3 billion lbs) of the global 2010 adhesives and sealants demand. Excluded are plywood, particle board, MDF binders and carpet backing adhesives. It is estimated that, by 2050, the BRIGS share of the global market could reach 40%. 

Binders. Binders should be elastic while still maintaining strong adhesion to the substance being bound. The resulting product can be soft and flexible as in a carpet backing or stiff and hard as in an abrasive. Thermoplastic rubber has the capacity for great extension, particularly with inert fillers. An example of a flexible carpet backing is shown in Table 20. 

Carpet backing is - after paints, paper and adhesives applications - the fourth largest bulk application of emulsion polymers. About 700 000 tons per year (dry) are used worldwide, mainly as binder for the backing of tufted carpets. The function of a carpet backing is to anchor the pile fibres in place and to improve dimensional stability of the tufted material. 

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