Ethylene copolymer latices

Chem. Descrip. Vinyl acetate-ethylene copolymer latex CAS 24937-78-8... 

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). 

Continuous emulsion copolymerization processes for vinyl acetate and vinyl acetate—ethylene copolymer have been reported (59—64). CycHc variations in the number of particles, conversion, and particle-size distribution have been studied. Control of these variations based on on-line measurements and the use of preformed latex seed particles has been discussed (61,62). 

In contrast to other polymers the resistance to water permeation is low due to the hydrolysis of the poly(vinyl acetate) (163,164). Ethylene copolymers have been developed which have improved water resistance and waterproofness. The polymer can be used in the latex form or in a spray-dried form which can be preblended in with the cement (qv) in the proper proportion. The compressive and tensile strength of concrete is improved by addition of PVAc emulsions to the water before mixing. A polymer-soHds-to-total-soHds ratio of ca 10 90 is best. The emulsions also aid adhesion between new and old concrete when patching or resurfacing. 

HMX HMX HMX HMX HMX HMX HMX HMX HMX HMX HMX HMX HNS NTO NTO/HMX NTO/HMX NTO/HMX PETN PETN PETN PETN PETN PETN PETN PETN PETN PETN RDX RDX RDX RDX RDX RDX RDX RDX RDX RDX RDX RDX RDX TATB/HMX Cariflex (thermoplastic elastomer) Hydroxy-terminated polybutadiene (polyurethane) Hydroxy-terminated polyester Kraton (block copolymer of styrene and ethylene-butylene) Nylon (polyamide) Polyester resin-styrene Polyethylene Polyurethane Poly(vinyl) alcohol Poly(vinyl) butyral resin Teflon (polytetrafluoroethylene) Viton (fluoroelastomer) Teflon (polytetrafluoroethylene) Cariflex (block copolymer of butadiene-styrene) Cariflex (block copolymer of butadiene-styrene) Estane (polyester polyurethane copolymer) Hytemp (thermoplastic elastomer) Butyl rubber with acetyl tributylcitrate Epoxy resin-diethylenetriamine Kraton (block copolymer of styrene and ethylene-butylene) Latex with bis-(2-ethylhexyl adipate) Nylon (polyamide) Polyester and styrene copolymer Poly(ethyl acrylate) with dibutyl phthalate Silicone rubber Viton (fluoroelastomer) Teflon (polytetrafluoroethylene) Epoxy ether Exon (polychlorotrifluoroethylene/vinylidine chloride) Hydroxy-terminated polybutadiene (polyurethane) Kel-F (polychlorotrifluoroethylene) Nylon (polyamide) Nylon and aluminium Nitro-fluoroalkyl epoxides Polyacrylate and paraffin Polyamide resin Polyisobutylene/Teflon (polytetrafluoroethylene) Polyester Polystyrene Teflon (polytetrafluoroethylene) Kraton (block copolymer of styrene and ethylene-butylene)... 

A 62 35 3 ethyl acrylate-methyl methacrylate-acrylic acid copolymer latex was prepared by continuous addition of the monomer mixture over a 4-hour period at 80° (22). The emulsifier was a sodium lauryl ether sulfate-nonylphenol polyoxyethylene adduct (20 moles ethylene oxide) mixture, the initiator a potassium persulfate-sodium hydroxulfite mixture, and the buffer a sodium bicarbonate-potassium hydroxide mixture. The final latex of pH 6.5 contained 40% solids, and the Tg of the copolymer was 13°. 

The formation of coagulum is observed in all types of emulsion polymers (i) synthetic rubber latexes such as butadiene-styrene, acrylonitrile-butadiene, and butadiene-styrene-vinyl pyridine copolymers as well as polybutadiene, polychloroprene, and polyisoprene (ii) coatings latexes such as styrene-butadiene, acrylate ester, vinyl acetate, vinyl chloride, and ethylene copolymers (iii) plastisol resins such as polyvinyl chloride (iv) specialty latexes such as polyethylene, polytetrafluoroethylene, and other fluorinated polymers (v) inverse latexes of polyacrylamide and other water-soluble polymers prepared by inverse emulsion polymerization. There are no major latex classes produced by emulsion polymerization that are completely free of coagulum formation during or after polymerization. 

In Figure 6 the result of a rapid density gradient centrifugation is shown using this system. It deals with a graft copolymer latex of butadiene and styrene acrylonitrile. The gradient media are different mixtures of 3-butene-2-ol and ethylene glycol. 

Use Polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, and polyvinyl chloride-acetate resins, used particularly in latex paints, paper coating, adhesives, textile finishing, safety glass interlayers. A vinyl acetate-ethylene copolymer is available for specialty products. 

Akay, G. Tong, L. Bakr, H. Choudhery, R.A. Murray, K. Watkins, J. Preparation of ethylene vinyl acetate copolymer latex by flow induced phase inversion emulsification. J. Mater. Sci. 2002, 37, 4811 818. 

Aqueous dispersions of poly(vinyl acetate) and vinyl acetate-ethylene copolymers, homo- and copolymers of acrylic monomers, and styrene-butadiene copolymers are the most important types of polymer latexes today. Applications include paints, coatings, adhesives, paper manufacturing, leather manufacturing, textiles and other industries. In addition to emulsion polymerization, other aqueous free-radical polymerizations are applied on a large scale. In suspension polymerization a water-irnrniscible olefinic monomer is also polymerized. However, by contrast to emulsion polymerization a monomer-soluble initiator is employed, and usually no surfactant is added. Polymerization occurs in the monomer droplets, with kinetics similar to bulk polymerization. The particles obtained are much larger (>15 pm) than in emulsion polymerization, and they do not form stable latexes but precipitate during polymerization (Scheme 7.2). 

Seals may be permanent, semi-permanent, or peelable. Peelable systems usually consist of ethylene copolymers, possibly modified with polyethylene, or other films, lacquers or dispersions. Some are resealable, hence are not strictly tamper-resistant. Cold seals, typically based on a rubber latex, are usually non-resealable. These may employ the cold seal only in the area of the seal, hence avoiding any or limited product contact. Pattern systems are widely used for surgical materials and instruments. 

Vinyl Acetate, Homo- and Copolymer Latexes Vinyl Acetate Comonomer (butyl acrylate, ethylene, vinyl ester of versatic add) Partially Hydrolyzed Polyvinyl Alcohol Sodium Bicarbonate Hydrogen Peroxide (35%) Sodium Formaldehyde Sulfoxylate Water 70.0-100.0 0.0-30.0 6.0 0.3 0.7 0.5 80.0... 

Daniels and Lenney [32] give a detailed process description of a two-reactor CSTR system used to produce ethylene-vinyl acetate (EVA) copolymer latexes. A seed latex is fed to the first reactor. Korte and Silling [33] employed a tube-CSTR system for producing acrylonitrile-vinylacetate-acetate-styrene copolymers. The PFT generated the seed for the CSTR which was also fed with a stream which by-passed the tube. 

These sueeessful examples of eharaeterizing latex systems are possible only when thermal expansion coefficients are known. Unfortunately, this parameter is not known for many latex polymers. This problem becomes even more complicated for latex systems than for emulsions because the value of the thermal expansion depends strongly on the chemical composition of the polymer. Figure 20 illustrates this fact for several ethylene copolymers with different ethylene contents. Variation of the ethylene content from 5 to 10% was found to cause significant change in the attenuation spectra. This change is associated with the thermal expansion coefficient, but not the particle size. 

Chem. Descrip. Ethylene-vinyl chloride copolymer latex Uses Coating binder and saturant for paper and paperboard applies. binder for flame retardant fabrics, heat sealable nonvirovens useful in heat seal adhesive appiics. or where a moisture barrier is required binder for nonwovens and textiles imparts flexibility and water resist, to caulks, mastics, barrier coats in building applies., low MTVR coalings Features Inherently flame retardant... 

Uses Defoamer for stripping, foam knock-down, and latex handling for pressure-sensitive adhesives, gravure inks, paints defoamer for food-contact coatings, paper/paperboard food pkg. adhesives Features Easily dispersible multi-component very effective with ethylene copolymers and compds. 

Copolymer latices of styrene and acrylates (mainly butyl acrylate) were synthesised. Sodium dodecyl sulphate and ethoxylated nonyl phenol containing ten ethylene oxide units were used as surfactants and potassium persulphate as initiator. A coating for paper was made on the basis of the copolymer latices and white pigments. The performance of the coated paper was measured. By varying experimental conditions such as comonomer proportion and amounts of emulsifiers and of initiator, a copolymer latex suitable for paper coating was prepared. Paper coated with latex showed satisfactory properties in... 

Free-radical copolymerizations can be carried out by any one of the usual methods used for the preparation of the homopolymers themselves. Particularly advantageous for the synthesis of these copolymers are emulsion copolymerizations [271]. Separate emulsions each containing one, two, or more monomers can be equilibrated with one another and then polymerized to give the copolymer latex. Random ethylenevinyl acetate copolymers, which have found considerable commercial use in adhesives, coatings, and molding compounds are prepared by various techniques. Those polymers that have high ethylene contents are normally prepared by bulk or solution methods while high-pressure emulsion techniques are employed for copolymers rich in vinyl acetate [272]. Vinyl acetate is often polymerized in minor amounts with vinyl chloride and with acrylic monomers to modify their polymers and to impart special properties, such as plasticization and dyeability. 

An example of a complex seeded polymerization is given in Procedure 4-5. In this process the pH of the seed latex should be maintained between 1 and 3.5, possibly by gradually adding carboxylated monomers or by the use of appropriate acids or bases. The system is interesting since it is a patented method for the production of a vinyl chloride-ethylene copolymer with a 2-thylhexyl acrylate seed polymer and additions of acrylic acid. The procedure is given here for reference only. Not the use of preemulsified monomers in this procedure. 

Acrylics. Acetone is converted via the intermediate acetone cyanohydrin to the monomer methyl methacrylate (MMA) [80-62-6]. The MMA is polymerized to poly(methyl methacrylate) (PMMA) to make the familiar clear acryUc sheet. PMMA is also used in mol ding and extmsion powders. Hydrolysis of acetone cyanohydrin gives methacrylic acid (MAA), a monomer which goes direcdy into acryUc latexes, carboxylated styrene—butadiene polymers, or ethylene—MAA ionomers. As part of the methacrylic stmcture, acetone is found in the following major end use products acryUc sheet mol ding resins, impact modifiers and processing aids, acryUc film, ABS and polyester resin modifiers, surface coatings, acryUc lacquers, emulsion polymers, petroleum chemicals, and various copolymers (see METHACRYLIC ACID AND DERIVATIVES METHACRYLIC POLYMERS). 

Acrylonitrile—Butadiene—Styrene. ABS is an important commercial polymer, with numerous apphcations. In the late 1950s, ABS was produced by emulsion grafting of styrene-acrylonitrile copolymers onto polybutadiene latex particles. This method continues to be the basis for a considerable volume of ABS manufacture. More recently, ABS has also been produced by continuous mass and mass-suspension processes (237). The various products may be mechanically blended for optimizing properties and cost. Brittle SAN, toughened by SAN-grafted ethylene—propylene and acrylate mbbets, is used in outdoor apphcations. Flame retardancy of ABS is improved by chlorinated PE and other flame-retarding additives (237). 

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