ABS latex

Emulsion Process. The emulsion (79,80) ABS process involves two steps, production of a mbber latex and subsequent polymerization of styrene and acrylonitrile in the presence of the mbber latex to produce an ABS latex. This latex is then processed to isolate the ABS resin (81,82). 

After the mbber latex is produced, it is subjected to further polymerization in the presence of styrene (CgHg) and acrylonitrile (C H N) monomers to produce the ABS latex. This can be done in batch, semibatch, or continuous reactors. The other ingredients required for this polymerization are similar to those required for the mbber latex reaction. 

The ABS polymer is recovered through coagulation of the ABS latex. Coagulation is usually achieved by the addition of an agent to the latex which destabilizes the emulsion. The resulting slurry can then be filtered or centrifuged to recover the ABS resin. The wet resin is dried to a low moisture content. A variety of dryers can be used for ABS, including tray, fluid bed, and rotary kiln type dryers. 

M ass Process. In the mass (or bulk) (83) ABS process the polymerization is conducted in a monomer medium rather than in water. This process usually consists of a series of two or more continuous reactors. The mbber used in this process is most commonly a solution-polymerized linear polybutadiene (or copolymer containing sytrene), although some mass processes utilize emulsion-polymerized ABS with a high mbber content for the mbber component (84). If a linear mbber is used, a solution of the mbber in the monomers is prepared for feeding to the reactor system. If emulsion ABS is used as the source of mbber, a dispersion of the ABS in the monomers is usually prepared after the water has been removed from the ABS latex. 

In the industrial production of structured AN-Bu-St (ABS) latex particles, the grafting copolymerization of AN and St on crossUnked polybutadiene (PB) seed latex is carried out in emulsion polymerization. Therefore, information on the effect of PB crosslinking density on the swelling of PB latex particles by a St-AN monomer mixture is very important for the production of ABS copolymers with desired properties. Mathew et al. [177] studied the effect of several thermodynamic parameters, such as the crosslinking density, particle size and monomer mixture composition on the swelling behavior of PB latex particles by pure St and AN, and St-AN mixtures of various compositions. They reported... 

Styrene is frequently used as part of some terpolymers with large practical utilization. One such copolymer is acrylonitrile-butadiene-styrene terpolymer (ABS). Usually it is made as poly(l-butenylene-graft-l-phenylethylene-co-cyanoethylene). This form of the copolymer can be made by grafting styrene and acrylonitrile directly on to the polybutadiene latex in a batch or continuous emulsion polymerization process. Grafting is achieved by the free-radical copolymerization of styrene and acrylonitrile monomers in the presence of polybutadiene. The degree of grafting is a function of the 1,2-vinyl content of the polybutadiene, monomer concentration, extent of conversion, temperature and mercaptan concentration (used for crosslinking). The emulsion polymerization process involves two steps production of a rubber latex and subsequent polymerization of styrene and acrylonitrile in the presence of the rubber latex to produce an ABS latex. 

Figure 8.1. TEM micrographs of (a) ABS resin and (b) as-polymerized ABS latex by the OsO staining and fixation method [Kato, 1967]. In micrograph (a), polybutadiene phase is stained. SAN particles are occluded in the rubber particles. In micrograph (b), a latex particle is embedded in agar-agar/polybutadiene latex mixture and stained by OsO. The occluded SAN particles are clearly seen. Surface grafted SAN partly covers the salami particle.

Uses ABS latex for waterproof and greaseproof coatings, ieather finishes, paints, paper coatings, and nonwoven binders and saturation food pkg. adhesives in resin-bonded filters for food contact Regulatory FDA21CFR 175.105,177.2260 Properties Sp.gr. 1.01 vise. 28 cps pH 10.3-11.0 surf. tens. 48 dynes/ cm (29 C) 3942% solids Hycai 1578X1 [Noveon]... 

Uses ABS latex for water and grease-resist, coatings, leather and textile finishing, nonwoven binders, paper coatings Properties Sp.gr. 1.01 vise. 80 cps pH 8.0 surf. tens. 42 dynes/cm 50% solids... 

Figure 3.6. Electron micrograph of an ultrathin section of a type G ABS latex specimen, showing the latex particles completely surrounded with AS copolymer. (Matsuo et al, 1969a.)...

FUNCTIONAL POLYMERS. I.xni. EMULSION COPOLYMERISATION OF MALEIMIDE TYPE MONOMERS WITH ACRYLONITRILE AND STYRENE IN ABS LATEXES Bartus J Simonsick W J Vogl O Brooklyn,Polytechnic University DuPont de Nemours E.I., Co.Inc. 

Initially compounding was mainly performed between amorphous polymers and elastomers, resulting in a polymer matrix with small domains of elastomers. This morphology can increase the mechanical properties considerably. In later developments special attention was paid to better and controlled phase separation, to control the domain size, and to increase the impact strength, as for instance in high-impact polystyrene (HIPS) and in ABS-latex mixtures. The search for better compatibility between the phases leads also to fully compatible combinations of polymers. Although over 300 pairs of miscible polymers are known (2), only a few systems have actually been commercialized, like PS/PPE... 

Several possibilities may be imagined for the detailed morphological structure within the latex particles. First, a smooth gradation of composition from core to shell may exist. Alternatively, but less likely, there may be an abrupt composition boundary between the core and shell. Further, there may be phase separation within the core. Two possibilities are shown in Figure 6.12a. " The structure on the right models the known morphology of the ABS latexes. The structure on the left, however, is predicted for two cases (a) when the latex particles are too small to form cellular... 

Resin Recovery Process. Typically, the polymer is recovered by the addition of coagulants which destabilize the ABS latex. Different coagulants are used depending on the surfactant. Thus, strong and weak acids work well with fatty acid soaps, and metal salts are used with acid stable soaps (106). The use of nonionic coagulants has also been reported (107,108). Acrylic latices have been... 

Rgure 13.12 Morphology of a ABS latex particle, osmium tetioxide stained. Note the core-shell stmcture, with AS copolymer constituting the shell, and also AS domains inside of the polybutadiene mbber cote. 

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