Water-based adhesives latexes

Water is sometimes used as a solvent for water-soluble resins. Certain epoxy adhesives are available as water-based emulsion or latex formulations. In the early 1970s, during the time of the petroleum crisis, water-based adhesives were thought of as a possible replacement for solvent-based adhesives systems. However, water-based adhesives never met the lofty expectations primarily because of the time and energy required to remove water from the bond line, the corrosion that the water causes in drying ovens, and the poor moisture resistance of cured water-based adhesives. 

Water soluble thickeners, designed specifically for the water based adhesive and latex compounding industries, supplied as frost stable low viscosity high solids dispersions. 

Hexahydro-1,3,5-triethyl-s-triazine. Industrial preservative, prevents bacterial action in cutting oils, synthetic rubber latex, starch based adhesives, latex paint and aqueous slurries. It is soluble in acetone, ethyl alcohol, ether and water, moderately soluble in hydrocarbon solvents. 

Emulsion polymerization presents similar processing difficulties to those of suspension polymerization. The product has to be recovered, in this case usually by coagulation, and then washed and dried. Again it may be difficult to remove all traces of the surfactant, etc., used to stabilize the emulsion, as with the product from suspension polymerization. However, for some applications, such as for latex (water-based) paints and carpet adhesives, the aqueous product from emulsion polymerization may be used directly. For applications, such as these, it is possible to produce lattices (latexes) containing as high as 50% solids. 

Self-adhesive labels can be applied to most materials wood, plastic, metal, glass, paper and board. As the adhesives are resin-based (plasticised thermoplastics), migration problems can occur when they are applied to certain plastics (PVC, LDPE, etc.). Adhesive systems for pressure sensitive labels include latex and acrylic bases and adhesives which may be applied as a hot melt, or via a solvent, emulsion or dispersion base. Water-based adhesives are currently increasing in use. 

Uses Antifoam for water-based adhesive systems employing resin or latex binders and animal glues, and for paints, cementitious finishes, gravure inks defoamer in food-contact coatings, paper/paperboard food pkg. adhesives, coatings Features Good leveling... 

Chem. Descrip. Nonsilicone, mineral oil-based defoamer Uses Defoamer for emulsion paints, water-based adhesives and glues, polymerization, cleaners, wallpaper removers, latex masonry tinishes Properties Liq. 100%act. 

Uses Gellant, rheology control agent, thickener, stabilizer for aq. systems, latex-based architectural paints, traffic paints, sealants, caulks, water-based adhesives, FRP/GRP applies. binder for foundry mold coatings... 

Chem. Descrip. Tribulyl phosphate CAS 126-73-8 EINECS/ELINCS 204-800-2 Uses Flame retardant, plasticizer for nitrocellulose, cellulose acetate, chlorinated mbber. and vinyls antifoam for paper coalings, water-based adhesives, inks, textile sizes, detergent sol ns. high boiling solv. for lithographic inks latex paints also suitable for epoxy, PS, PVAc Prqietties Colorless liq. sp.gr. 0.980 (20/20 C) vise. 6 mPa s 11.7% P Phosflex 61B [AkzoNobeQ... 

Uses Tackifier for water-based adhesives and sealants based on acrylic, SIB, neoprene, VAE, or PVAc, esp. for pressure-sensitive adhesives, acrylic latexes modifier for EVA Features Solv.-ffee... 

CAS 2634-33-5 EINECS/ELINCS 220-120-9 Uses Microbiostat, preservative for aq. compositions such as o/w emulsions, water-based adhesives, latexes, emulsion paints, casein and rosin disps., textile spin-finish sol ns., pesticides, aq. slurries, inks, titanium dioxide slurries, tape joint compds., leather processing sol ns. preservation of fresh animal hides and skins food pkg. adhesives, paper food-contact slimicide... 

Uses Used in mfg. of coatings, adhesives, sealants, and encapsulants water-based adhesion primer for latex coatings concrete sealer aggregate binder... 

What of water-based adhesives We can apply some of the same principles and technology learned from solvent-applied adhesives to water-based systems. First, many of the polymers and elastomers available are the same (Table 2). Not only are these polymers available in latex form, but many are produced in latex form. The solid rubber used in solvent-based adhesives was derived from the latex, so one is actually eliminating a production step. Secondly, many of the resins the formulator has experience with and confidence in working with are available in dispersed form (Table 3). Some of these products have been available for a number of years and others are still in developmental stages. 

ELASTOMERS, RESIN MODIFIERS FOR WATER-BASE ADHESIVES 2. Styrene-Butadiene Latexes... 

There are two general types of water-based adhesives solutions and latexes.Solutions are made from materials that are soluble only in water or in alkaline water. Examples of materials that are soluble only in water include animal glue, starch, dextrin, blood albumen, methyl cellulose, and polyvinyl alcohol. Examples of materials that are soluble in alkaline water include casein, rosin, shellac, copolymers of vinyl acetate or acrylates containing carboxyl groups, and carboxymethyl cellulose. 

A summary is presented of topics discussed at a conference on adhesive tapes organised in Athens by AFERA. These included the use of iodopropynyl butyl carbamate for the protection of water-based adhesives from biological attack, the formulation of NR latex based adhesives with tackifiers in aqueous dispersion, the effects of silicon contamination on adhesion to plastics film supports treated in different ways, possible harmful effects... 

In order to eliminate harmful solvents which are flammable and sometimes noxious, adhesives manufacturers have developed water-based adhesives, based on rubber latex or polymer dispersions, which set quickly due to the addition of an activator that reacts quickly with the base polymer and induces its quick coagulation. But the mixing should be done during the spraying in order to avoid any coagulation and clogging into the gun. 

Latexes, as sold, will normally contain a bactericide. However when compounds are produced from these latexes the bactericide is diluted and other potentially biodegradable materials are included. Hence it is prudent to add bactericidal agents to water based adhesive compounds. 

Rubber and cellulosic-type solvent cements are used for attaching gaskets and blotters. Water based adhesives such as sodium silicate, starch, dextrin, and latex are used for a variety of applications such as labeling. 

Bentonite thickening agents are used in various water based adhesives, caulks and sealants including those based on proteins and starch, polyvinyl acetate emulsions, natural rubber latexes, acrylic emulsions, neoprene emulsions, butyl emulsions, nitrile emulsions, and SBR emulsions. 

There are two general types of water-based adhesives solutions and latexes. Solutions are made from materials that are soluble only in water or in alkaline water. There are two sources for the... 

Another form of water-based adhesive is the emulsion or latex which was mentioned in the first chapter. This is a means of providing water-based products in which the adhesive substance itself is not soluble in water but is dispersed in liquid droplets held in suspension in water. Examples include the natural rubber latex as well as PVA, acrylic emulsions and others. 

Emulsion Adhesives. The most widely used emulsion-based adhesive is that based upon poly(vinyl acetate)—poly(vinyl alcohol) copolymers formed by free-radical polymerization in an emulsion system. Poly(vinyl alcohol) is typically formed by hydrolysis of the poly(vinyl acetate). The properties of the emulsion are derived from the polymer employed in the polymerization as weU as from the system used to emulsify the polymer in water. The emulsion is stabilized by a combination of a surfactant plus a coUoid protection system. The protective coUoids are similar to those used paint (qv) to stabilize latex. For poly(vinyl acetate), the protective coUoids are isolated from natural gums and ceUulosic resins (carboxymethylceUulose or hydroxyethjdceUulose). The hydroHzed polymer may also be used. The physical properties of the poly(vinyl acetate) polymer can be modified by changing the co-monomer used in the polymerization. Any material which is free-radically active and participates in an emulsion polymerization can be employed. Plasticizers (qv), tackifiers, viscosity modifiers, solvents (added to coalesce the emulsion particles), fillers, humectants, and other materials are often added to the adhesive to meet specifications for the intended appHcation. Because the presence of foam in the bond line could decrease performance of the adhesion joint, agents that control the amount of air entrapped in an adhesive bond must be added. Biocides are also necessary many of the materials that are used to stabilize poly(vinyl acetate) emulsions are natural products. Poly(vinyl acetate) adhesives known as "white glue" or "carpenter s glue" are available under a number of different trade names. AppHcations are found mosdy in the area of adhesion to paper and wood (see Vinyl polymers). 

Lamination. la lamination a film is prepared by caleaderiag or extmsioa (see Laminated materials, plastic). It is thea adhered to a textile at a laminator by either an adhesive or sufficient heat which partially melts the film to obtain a mechanical bond. There are a variety of adhesives available for lamination, including solvent systems, water-base latex systems, and various forms of hot melt adhesives (qv). 

The increase of restrictive regulations on the use of organic solvents favoured the increasing use of latex-based adhesives. Because of the slow evaporation of water, these adhesives show less tack and can suffer bacterial attack. Infrared heaters and ovens can be used to favour the evaporation of water. Often a small amount of solvent (coalescing aid) is added to the latex system to improve wetting and coalescence of the latex particles. 

The most common adhesive system used for bonding continuous fibers and fabrics to rubber is resorcinol-formaldehyde latex (RFL) system. In general, RFL system is a water-based material. Different lattices including nitrile and SBR are used as the latex for the adhesive system. 2-Vinylpyridine-butadiene-styrene is the common latex used in the adhesive recipe. RFL system is widely being used in tires, diaphragms, power transmission belts, hoses, and conveyor belts because of its dynamic properties, adhesion, heat resistance, and the capacity to bond a wide range of fabrics and mbbers. 

The stabilizing of aqueous latexes succeeded by using emulsifiers (anionic, nonionic) and/or their mixture, steric stabilizators (polyvinyl alcohol (PVOH), hydroxyethyl cellulose, polyethylene glycol, new protective colloids etc.), and polymerizable surfaces active agents, in general. Vinyl acetate (VAc) emulsion homopolymers and copolymers (latexes) are widely used as binders in water-based interior and exterior architectural paints, coatings, and adhesives, since they have higher mechanical and water resistance properties than the homopolymers of both monomers [2, 4, 7]. 

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