1. Acrylate emulsion
Acrylate is the general term for acrylic acid and its homolog esters. Mainly includes methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, and butyl methacrylate. Acrylate can be self-polymerized or copolymerized with other monomers and is the primary raw material for producing acrylate emulsion.
Acrylate emulsion is an emulsion prepared by acrylate monomers (methyl acrylate, ethyl ester, butyl ester, butyl methacrylate) using an emulsion copolymerization method. Its solid content generally ranges from 40% to 50%. Acrylate emulsion has the characteristics of a bright and flexible coating film, and its adhesion, water resistance, alkali resistance, and weather resistance are all excellent. Its application scope is mainly exterior and interior wall high-grade decorative coatings. The performance of acrylate emulsion is much better than that of polyvinyl acetate emulsion, primarily when used on new cement or lime walls; it can better reflect its advantages because the coating film of acrylate emulsion is saponified by alkali Calcium salt is insoluble in water, while polyvinyl alcohol produced by saponification of vinyl acetate emulsion is water-soluble and has poor water resistance.
Various acrylate monomers can not only be copolymerized but also can be copolymerized with other monomers, such as styrene, often called pure acrylic emulsion , and vinyl acetate, called styrene-acrylic and ethylene-acrylic emulsion. Methyl methacrylate and styrene are hard monomers, ethyl acrylate butyl are soft monomers, and butyl is softer than ethyl. Through different proportions, copolymer emulsions with other properties can be obtained. Using styrene instead of methyl methacrylate as a hard monomer can significantly reduce costs.
2. Ethylene-vinyl acetate copolymer emulsion (EVA)
EVA emulsion is a copolymer aqueous dispersion system obtained by polymerizing vinyl acetate and ethylene emulsion. It is a milky white viscous liquid with a solid content of 50%-55%, a viscosity of 200mPa·S~3300MPa·S, and a pH value of 4.0-5.5. The lowest film forming temperature is -3°C~10°C, the glass transition temperature is Tx=-3°C~7°C, and the surface tension is 30mN/m.
In the molecules of EVA emulsion, due to the introduction of the vinyl group, the main chain of the polymer becomes soft, which has an internal plasticizing effect and avoids the migration and dialysis volatilization caused by the addition of low molecular weight plasticizers. The minimum film-forming and glass transition temperatures are lowered and are stable to oxygen, ozone, and ultraviolet rays. Its acid and alkali resistance, freeze-thaw resistance, and storage stability are better than PVAc emulsions. Exceptional adhesion, suitable wet viscosity and fast curing speed, alkali resistance, and creep resistance are better than acrylic emulsion, good water resistance, high-temperature resistance, and will not decompose at 250 ° C.
The waterproof mortar modified by EVA emulsion has excellent weather resistance, acid and alkali resistance, and ultraviolet resistance. It can be applied to the waterproof treatment of special-shaped roofs, repairing old roofs, and constructing colored roofs. It can also be used for bathroom waterproof coatings. Adding EVA emulsion to cement can not only significantly increase the strength of cement but also achieve excellent results in repairing concrete and anti-seepage treatment of reservoirs.
3. Styrene Acrylic Emulsion (SAE)
Styrene-acrylic emulsion is a milky white liquid with blue light obtained by copolymerization of styrene and acrylate, with a solid content of 40% to 45%, a viscosity of 80mPa S to 1500mPa S, and residual monomers <0.5%. The pH value is 8-9, the adhesion of styrene-acrylic emulsion is good, and the coating film is transparent, water-resistant, oil-resistant, heat-resistant, and aging-resistant.
4. Styrene-butadiene latex (SBR)
Styrene-butadiene latex is obtained by copolymerizing butadiene and styrene emulsion, referred to as SBR. The relative density of styrene-butadiene latex is 0.9-1.05, and the amount of bound styrene is 23%-85%. The amount of bound styrene in mass-produced styrene-butadiene latex is 23% to 25%, while the high styrene latex (SBR-HSL) combined styrene content is as high as 80% to 85%. The total solid content of styrene-butadiene latex prepared by the general method is 40% to 50%, while the entire solid content of high-solid latex is 63% to 69%.
The heat resistance of styrene-butadiene latex is better than that of natural rubber latex. After aging, it is not sticky and does not soften but hardens.
This type of latex combines the characteristics and properties of rubber and plastic and has excellent adhesion, heat resistance, abrasion resistance, acid resistance, alkali resistance, and chemical resistance. They are widely used in coatings, latex coats, adhesives, and cement concrete (mortar) modifications.
5. Neoprene latex (CR)
Neoprene latex is a rubber emulsion prepared by emulsion polymerization of 2-chloro-1,3-butadiene, referred to as CRL which has excellent comprehensive properties, such as strong adhesion and good film-forming performance. Both wet gel and dry film have high strength and are resistant to oil, solvent, heat, and Ozone aging and other properties, so it is widely used, but neoprene latex also has some shortcomings, such as poor cold resistance; it is a fluid liquid at room temperature, the viscosity increases when it is cooled below 10 ° C, and it becomes a paste when it is close to 0 ° C. The latex is frozen below 0°C, the emulsifier is destroyed and solidified, and it cannot be restored to the original latex state when reheated. Now, modified neoprene latex has appeared, such as the cold-resistant type prepared by copolymerization of a small amount of neoprene latex. The insulation performance of neoprene latex is slightly lower, and the storage stability is not good enough. Copolymerization of neoprene latex with acrylonitrile can improve the performance of resistance to aromatic solvents, and copolymerization with acrylic compounds can produce carboxylated neoprene latex, which has good adhesive properties, elasticity, and film-forming properties.
Neoprene latex can be divided into general-purpose latex, a homopolymer with anion and gel type, and unique latex with gel and solvent types, including copolymers with styrene, acrylonitrile, and methacrylic acid. Cationic latex usually uses tetraamine salt as a stabilizer.
Neoprene latex is widely used to modify coatings, adhesives, and asphalt cement concrete (mortar).
