Ethylene-vinyl acetate latexes

ALCOGUM 6625 and its dilutions, ALOCGUM 6940 and ALCOGUM 6945, may be used to thicken styrene-butadiene, acrylonitrile butadiene, neoprene, acrylic, vinyl actetate and ethylene-vinyl acetate latex compounds. In general they are most satisfactory thickeners for latexes which have an alkaline reaction although some success has been achieved in neutral or slightly acid systems. 

Poly (Ethylene-Vinyl Acetate) Latex EVAorVAE Pch2-ch2-ch2-ch- I... 

The binders vary quite widely—the most common being starch, soy protein and latexes in conjunction with other soluble polymers. Styrene-butadiene latexes have been the most popular but ethylene-vinyl acetate binders are also used. The method of polymer synthesis provides a way of modifying the properties of the latex. For example, adjustment of the ratio of styrene butadiene in the co-polymer gives rise to different degrees of softness or hardness. This property has a profound influence on the quality of the coating. It is also possible to co-polymerise monomers so as to introduce, for example, carboxy groups on to the surface of the latex particle which in turn assist in... 

Latexes are usually copolymer systems of two or more monomers, and their total solids content, including polymers, emulsifiers, stabilizers etc. is 40-50% by mass. Most commercially available polymer latexes are based on elastomeric and thermoplastic polymers which form continuous polymer films when dried [88]. The major types of latexes include styrene-butadiene rubber (SBR), ethylene vinyl acetate (EVA), polyacrylic ester (PAE) and epoxy resin (EP) which are available both as emulsions and redispersible powders. They are widely used for bridge deck overlays and patching, as adhesives, and integral waterproofers. A brief description of the main types in current use is as follows [87]. 

J.L. Walker and PR. Mudge, Ethylene vinyl acetate polymers for latex caulks, US Patent 5120 785, assigned to National Starch and Chemical Investment Holding Corporation (Wilmington, DE), June 9,1992. 

It has been shown that tensile shear and peel strength for several latex polymers (ethylene vinyl acetate, polyvinyl alcohol, ethylene vinyl chloride, polyvinyl chloride, and acrylic) can be significantly increased by the addition of 10 percent by weight of an epoxy emulsion cured with a tertiary amine curing agent.17 The epoxy modification improves the bond strength in all cases. The degree of improvement is dependent on the selection of the latex type and the chemistry of the latex polymer. 

Not all solvent adhesives will he replaced with latexes per se. For some applications, hot melt adhesive systems are heing developed. However, just as ethylene-vinyl acetate copolymers produced by emulsion polymerization are a major component of many hot melt systems, suitably designed emulsion polymers to meet specific requirements will probably he present in these systems, too. 

TNPP is used as a phospite antioxidant and a stabilizer for elastomers such as SBR, NBR, and SIS. Used as a stabilizer and a chelator/complexing agent in PC, PE, PP, PVC, copolymers such as ABS (Acrylonitrile-Styrenic based), SBR, and EVA (Ethylene-vinyl acetate) and in polymer latex and other aqueous systems. TNPP also prevents gel formation during polymerization finishing, storage, and factory processing. 

Akay, G. Tong, L. Bakr, H. Choudhery, R.A. Murray, K. Watkins, J. Preparation of ethylene vinyl acetate copolymer latex by flow induced phase inversion emulsification. J. Mater. Sci. 2002, 37, 4811 818. 

Specialties and intermediates consist of ethylene oxide derivatives (polyethylene glycol, surfactants, amines, deicing fluids, heat transfer fluids, lubricants, and solvents) solvent and emulsion systems (alcohols, acrylics, vinyl acetate, latexes, and modifiers) for use in paints, adhesives, and household... 

In particular, the commercial latexes widely used in the world are styrene-butadiene rubber (SBR), polychloroprene rubber (CR), polyacrylic ester (PAE) and poly(ethylene-vinyl acetate) (EVA) copolymers. Most commercial polymer latexes for cement modifiers contain proper antifoaming agents, and can be generally used without the addition of the antifoaming agents during mbcing. 

Since the 1940s continuous polymerization processes have been developed for a variety of products and with different reactor configurations. Latex products manufactured in continuous systems include polychloroprene and other synthetic elastomers, ethylene-vinyl acetate copolymers, components for engineering plastics and coating formulations. 

Daniels and Lenney [32] give a detailed process description of a two-reactor CSTR system used to produce ethylene-vinyl acetate (EVA) copolymer latexes. A seed latex is fed to the first reactor. Korte and Silling [33] employed a tube-CSTR system for producing acrylonitrile-vinylacetate-acetate-styrene copolymers. The PFT generated the seed for the CSTR which was also fed with a stream which by-passed the tube. 

Research on the effect of monomer ratio in copolymer dispersions [e.g., SBR latex, poly (ethylene-vinyl acetate) (EVA) and poly (styrene-acrylic ester) (SAE) emulsions] on the strength of polymer-modified mortar using copolymer dispersions [21-23]... 

Different types of water-based emulsions are used in EPI adhesives. The most common are poly(vinyl acetate) (PVAc) emulsion, ethylene vinyl acetate (EVAc) emulsion, vinyl acetate-acrylate copolymerized (VAAC) emulsion, acrylic-styrene (AcSt) emulsion or styrene-butadiene rubber (SBR) latex or modified versions of these emulsion types [1, 8, 9], It has also been reported that tri- or ter-polymer emulsions like vinyl acetate-butyl acrylate-hydroxypropyl methacrylate or emulsions with different combinations of block copolymers can be used [4], Emulsion polymers containing cross-linking functional groups are especially well suited [4,6, 9]. The choice of emulsion(s) will, to a large extent, influence the adhesive properties such as setting time, bond quality, heat resistance, and moisture resistance. EPI adhesive systems are, however, very complex and the total composition (including the choice of cross-linker) and the interaction between the different components will determine the properties of the adhesive. Due to this it is difficult to describe in detail the effect of choosing one type of emulsion over the other. 

Continuous stirred-tank reactors (CSTRs) are used for large productions of a reduced number of polymer grades. Coordination catalysts are used in the production of LLDPE by solution polymerization (Dowlex, DSM Compact process [29]), of HDPE in slurry (Mitsui CX-process [30]) and of polypropylene in stirred bed gas phase reactors (BP process [22], Novolen process [31]). LDPE and ethylene-vinyl acetate copolymers (EVA) are produced by free-radical polymerization in bulk in a continuous autoclave reactor [30]. A substantial fraction of the SBR used for tires is produced by coagulating the SBR latex produced by emulsion polymerization in a battery of about 10 CSTRs in series [32]. The CSTRs are characterized by a broad residence time distribution, which affects to product properties. For example, latexes with narrow particle size distribution cannot be produced in CSTRs. 

For lamination, waterborne adhesives have actually been used in manufacturing flexible packaging and industrial laminates (91). Other latexes used besides acrylic are vinyl acetate, ethylene-vinyl acetate, vinylidene chloride, etc. The flexible packaging systems using these adhesives are PVDG-Gello/LDPE, OPP/OPP,... 

Cellulose acetate natural rubber (latex), polyisobutylene rubber, neoprene rubber, polyvinyl acetate, ethylene vinyl acetate, polyacrylate (carboxylic), cyanoacrylate, polyamide (versamid), phenoxy, polyester + isocyanate, nitrile-phenolic, polyurethane, and resorcinol-formaldehyde. 

Latex adhesives, of which there are many types (Nitrile rubber adhesives (NBR), SBR, Ethylene-vinyl acetate copolymers, acrylics, polyvinylidene chloride, etc.), should ideally be cross-linkable (for wash and dry-clean resistance), preferably with a low cure (reaction) temperature (see Reaction setting adhesives), as some fibres, such as polypropylene, may be damaged by high temperatures. The binder (adhesive) type can markedly affect physical properties and performance the amount of hard and soft polymer in the binder controls the sofmess of the finished product. Most binders impart adequate dry-state adhesion and so the choice of adhesive is usually governed by secondary requirements such as the method and conditions of application and costs. 

Adhesives are used in tufted carpets to anchor and stabilize the yarns they can also be used to attach a foam backing or a laminated secondary backing. Latices predominate with SBR (cross-linked) being the most widely used EVA latex (see Ethylene-vinyl acetate copolymers) is cheaper but has lower bond strength and is water sensitive. Other adhesives used are PVC plastisols in carpet tiles and hot melts and two-component polyurethanes in top-quality products (because hot melts and polyurethanes are relatively expensive). 

Water-based dispersions or emulsions such as polyvinyl acetate, acrylics, polyvinyl chloride and polyvinyl alcohol with plasticizers and tackifiers. In addition, this range can include urea formaldehyde and phenolic adhesives, resins, natural adhesives produced from starch, dextrin, casein, animal glues (see Polyvinyl alcohol in adhesives, Phenolic adhesives single-stage resoles. Phenolic adhesives two-stage novolacs. Animal glues and technical gelatins) and rubber latex (see Emulsion and dispersion adhesives). Solvent-free 100% solids such as polyurethane. Hot melt adhesives include Ethylene-vinyl acetate copolymers, polyolefins, polyamides, polyesters with tackifiers and waxes. More recent additions include cross-linkable systems. 

Fabrics that are woven together from thread or yam are referred to as textiles, whereas shorter fibres bound together in a random, porous fashion are called nonwovens. In either case, crosslinkable latexes are extensively used as binders to improve stability, durability, and chemical resistance (205), and flame retardance (413). Acrylic copolymers are the most common class of binders, although other copolymers, such as styrene-butadiene or ethylene-vinyl acetate (242, 255) copolymers are often used when required by cost (247) or performance. The softness (flexibility) or hardness (strength) of the fabric is controlled through the glass transition temperature of the latex binder. 

Various workers have applied this combination of techniques to studies carried out on ethylene-vinyl acetate copolymers [161], chlorinated natural rubber latex [165], and polyacrylonitrile [166]. 

Latex The film forming resin which acts as the binder between the pigment particles and the substrate. Ethylene/vinyl acetate and styrene/acrylic polymers are well known, and additional monomers are sometimes utilised to obtain the optimum film forming, durability and gloss properties. 

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