Copolymer latex

Vinylidene Chloride Copolymer Latex. Vinyhdene chloride polymers are often made in emulsion, but usuaUy are isolated, dried, and used as conventional resins. Stable latices have been prepared and can be used direcdy for coatings (171—176). The principal apphcations for these materials are as barrier coatings on paper products and, more recently, on plastic films. The heat-seal characteristics of VDC copolymer coatings are equaUy valuable in many apphcations. They are also used as binders for paints and nonwoven fabrics (177). The use of special VDC copolymer latices for barrier laminating adhesives is growing, and the use of vinyhdene chloride copolymers in flame-resistant carpet backing is weU known (178—181). VDC latices can also be used to coat poly(ethylene terephthalate) (PET) bottles to retain carbon dioxide (182). 

Speciali2ed copolymer latices, which are inherently and permanently tacky, are available as pressure-sensitive emulsions. They are mechanically stable and have excellent machinabiUty. They are compatible with many other PVAc latices and, therefore, can be easily blended with other resins for modification of surface tack, peel strength, and creep. 

Table 10 The Size of the Uniform Copolymer Latices Prepared by Direct Soapless Emulsion Copolymerization [113,114]...

The soapless seeded emulsion copolymerization method was used for producing uniform microspheres prepared by the copolymerization of styrene with polar, functional monomers [115-117]. In this series, polysty-rene-polymethacrylic acid (PS/PMAAc), poly sty rene-polymethylmethacrylate-polymethacrylic acid (PS/ PMMA/PMAAc), polystyrene-polyhydroxyethylmeth-acrylate (PS/PHEMA), and polystyrene-polyacrylic acid (PS/PAAc) uniform copolymer microspheres were synthesized by applying a multistage soapless emulsion polymerization process. The composition and the average size of the uniform copolymer latices prepared by multistage soapless emulsion copolymerization are given in Table 11. 

Figure 19 The scanning electron micrographs of the polystyrene seed latex and the copolymer latices carrying carboxyl, hydroxyl and amine functional groups, (a) PS/PAA, (b) PS HEMA, (c) PS/PDMAEM. The original SEM photographs were taken with 10,000 x magnification and reduced at a proper ratio to place the figure. (From Ref. 93. Reproduced with the permission of John Wiley Sons, Inc.)...

The particles have a relatively uniform density of about 0.95 g cm-3 and hence a content of poly(butadiene) of 59 percent (ratio of the weight styrene/ acrylonitrile = 88/12). With this gradient system the investigation of the chemical composition and heterogeneity of nearly all butadiene copolymer latices is possible. The experiment needs about 1 hour. 

More recent investigations revealed that the vinyl esters of these branched acids are excellent base materials for preparing paint latices (3, 8, 9, 10, 11, 13, 14). Their use as comonomer in vinyl acetate copolymer latices imparts improved alkali resistance and weatherability to the paint films. 

Mechanical Stability of Vinyl Chloride Homopolymer and Copolymer Latices... 

The object of this study was to clarify some aspects of the mechanism of shear-induced flocculation in colloidal dispersions. Vinyl chloride homopolymer and copolymer latices were prepared by emulsion polymerization using sodium dodecyl sulphate as emulsifier. Agglomeration behavior in these latices was studied by measuring the mechanical stability using a high speed stirring test. The latex particle size was measured by an analytical centrifuge. Molecular areas of emulsifier in the saturated adsorption layer at the surface of homopolymer and copolymer latex particles were estimated from adsorption titration data. 

The stability of the copolymer latices shown in Figure 7 are near the maximum level both for the vinyl acetate and the VeoVa copolymer. 

Figure 7. Mechanical stability of PVC copolymer latices. E-ffect of copolymerization. Polymer 45% by weight. Na ...

Vinyl chloride is built into the copolymer somewhat faster than the vinyl esters. The latices described in Figure 12. were prepared with the same initial concentration of emulsifier. The difference in particle size between the homopolymer and the copolymer latices are considered to be within experimental error. 

PALMGREN Vinyl Chloride Homopolytner and Copolymer Latices 275... 

Ha MLP, Grady BP, LoUi G et al (2(X)7) Composites of single-walled carbon ntinotubes and styrene-isoprene copolymer latices. Macromol Chem Phys 208 446-456... 

For many years styrene-butadiene (CH2=CH-CH=CH2) copolymers were used in the USA in cheap latex coatings for house interiors. More recent developments have been the formulation of primers and undercoats based on latices with good adhesion for wood and the use of ethylene/vinyl chloride/vinyl acetate copolymer latices in house paints. 

Because of the water-solubility of HMMM resins, they can be used with water-reducible alkyds, polyesters or acrylics and with acrylic copolymer latices to produce water-based counterparts of the above stoving finishes. Such coatings are not usually free of small proportions of water-miscible co-solvents, e.g. butyl Cellosolve , and ammonia or amines (see p. 108). 

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