Starch-latex binder

BERSET 2425 is a melamine based coating insolubilizer. It is a very effective crosslinker for starch, protein, P.V.A., and latex binders in pigmented, or non-pigmented coatings. BERSET 2425 is sufficiently reactive so that 80-90% of insolubilization is achieved directly off the machine and completely developed within a day. Unlike other crosslinkers, BERSET 2425 has little or no effect on coating viscosities. BERSET 2425 has an advantage of having a very low free formaldehyde. 

Chem. Descrip. Starch/latex copolymer Uses Binder for coating paper... 

Formaldehyde resins Starch and dextrin adhesives Styrene-butadiene latex binders Natural rubber latex Flot melts Solvent-based adhesives Pressure-sensitive adhesives Inorganic adhesives. 

Uses Defoamer for foods, pharmaceuticals, antifreeze, detergent soi ns., cutting oils, industrial soaps, starch slurry, latex binder for carpets, carpet print pastes, hide glues, lens grinding mixes, inks, calcium chloride brines, textile print pastes, antifoam formulating... 

Uses Industrial defoamer for highly acidic and alkaline systems, adhesives, antifreeze, brines, hotaq. systems, inks, insecticides, painte, resin polymerization, starch processing, petrol., latex binders and emulsions, textile, paper Properties Liq. sp.gr. 1.00 flash pt. (PMCC) none pH 7.0 10% silicone... 

The traditional binder is - casein, which is more and more replaced by - starch derivatives, ->dex-trins, latex binders and soy protein isolates (defatted soy meal is extracted with water, and the protein is precipitated by acids). 

The solvent should have high solvability with no or very low odor. Two examples are SAS-296 (diarylalkane, Nippon Petroleum Chemicals) and KMC-113 (dialkylnaphthalene, Kureha Chemicals). Latex is used as binder. Wheat starch functions as a stilt preventing the rupture of microcapsules... 

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... 

Many coatings will use latex as a binder either singly or in combination with starch. Addition of specialty starch allows cost control and depending on the quality demanded, the level of starch can be varied. Many formulas will use 16 to 18 parts of binder based on the clay and frequently ratios of 5 starch and 12 latex are used. 

Starch can be enzymically converted in the presence of pigment. The conversion follows a similar time-temperature cycle as in neat starch conversion. The pigment will adsorb a portion of the enzyme adsorption can be minimized by the addition of sodium silicate to the mixture prior to the addition of the enzyme (Vanderbilt process). Even with silicate treatment, a higher quantity of enzyme will be required to reach a specific viscosity target. Other coating components, such as latex and lubricants, have to be added after the conversion. The Vanderbilt process is now rarely used for the preparation of coating binder. 

Special starch products have been developed for use as thickeners in coatings that are based on synthetic latex or resin binders. Starch-based thickeners can have associative properties when substituted with a hydrophobic reagent. They provide an alternative for cellulose-based thickeners, but their use is limited. 

Materials from starch crosslinked with melamine-formaldehyde, methylated melamine-formaldehyde, and other amine-aldehyde resins were patented as binders for filter paper,1336 milk filter sheet materials,1338 and aqueous papercoating compositions containing clay, titanium(IV) oxide, butadiene-styrene latex, and calcium octadecanoate.1396,1397 Foams for filters were developed.1398 A heatsetting adhesive was one of the first applications reported for starch crosslinked by urea-formaldehyde and phenol-formaldehyde resins.1331,1340-1342,1347,1372,1399... 

Uses Emulsifier starch modifier in adhesives, textile sizing, paper sizing protective colloid pigment binder and dispersant film-former vise, modifier latex stabilizer barrier coatings antiresoiling additives strippable coatings water treatment... 

---