Claims
- 1. In a process of preparing an emulsion polymerized latex addition polymer in which the molecular weight of the polymer is widely divergent and the Tg of the polymer is between 10.degree. C. and -60.degree. C., the improvement in which a monomer mixture which is at least predominantly of alpha, beta-monomethylenically unsaturated monomers and is polymerized by a free radical method, the polymerization being conducted in stages in which the first stage of the polymerization is conducted in the absence of a chain transfer agent, whereby a high molecular weight polymer fraction is obtained, and at least one additional stage of the polymerization is conducted in the presence of the chain transfer agent, whereby at least one low molecular weight fraction is obtained, in which from about 5 to 70% of the monomers are polymerized to give a fraction which has a M.sub.n of between about 500 and 100,000 and from about 30% to 90% of the monomers are polymerized to give a fraction which has a M.sub.n of about 100,000 to at least 2,000,000 and the ratio of M.sub.w /M.sub.n is from 15 to 150, the molecular weight being determined by gel permeation chromatography.
- 2. A process of claim 1 conducted in stages within a reactor in which at least one stage of the polymerization reaction is conducted essentially in the absence of a free chain transfer agent and at least one stage of the reaction is conducted in the presence of a free chain transfer agent, said T.sub.g being from about -5.degree. C. to about -40.degree. C.
- 3. The method of claim 2 in which at least about 30% of the monomers are polymerized in said first stage.
- 4. The process of claim 3 in which there are at least two stages in which monomer and chain transfer agent are introduced, the quantity of chain transfer agent being greater in the last stage of the reaction, there thus being a first polymerization stage in the absence of chain transfer agent, a second polymerization stage in which a chain transfer agent is utilized, and a third stage in which a larger amount of chain transfer agent is utilized.
- 5. The process of claim 4 in which 30% to 90% of the monomer mix is reacted when the initial chain transfer agent is introduced and a second introduction of chain transfer agent takes place when between about 50% and 95% of the monomer mix has been reacted.
- 6. The process of claim 5 in which the initial introduction of chain transfer agent takes place when at least 45% of the monomers have been introduced into the reactor and polymerized, the second introduction of monomer and chain transfer agent takes place when at least 60% of the monomers have been introduced into the reactor and polymerized, and the ratio of M.sub.w /M.sub.n is from 20 to 90.
- 7. The process of claim 6 in which the polymer contains 0.5-15% of a carboxylic acid selected from the group consisting of acrylic acid, itaconic acid, fumaric acid, methacrylic acid, and crotonic acid, and mixtures thereof, 0-25% by weight of another addition polymerizable .alpha., .beta. monoethylenically unsaturated monomer including one or more of an ester of methacrylic acid with an alcohol having from 1 to 18 carbon atoms, vinyl versatate, styrene, vinyl toluene, vinyl acetate and acrylonitrile, the balance of the copolymerized monomers being one or more esters of acrylic acid with an alcohol having from 1 to 18 carbon atoms.
- 8. The process of claim 7 in which the carboxylic acid is a mixture of 5-10% of methacrylic acid with 0.5-2% of itaconic acid, and said ester or esters of acrylic acid have 1 to 8 carbon atoms.
- 9. The process of claim 7 in which the monomers consist essentially of ethyl acrylate, butyl acrylate and said acids.
- 10. The process of claim 9 in which the chain transfer agent is selected from long chain alkyl mercaptans, dialkyl xanthogen disulfides, mercaptocarboxylic acids, alkarylmercaptans, long chain alcohols, and halogenated hydrocarbons.
Parent Case Info
This is a continuation of application Ser. No. 313,400 filed Oct. 21, 1981, abandoned, which is a continuation of Ser. No. 119,728 filed Feb. 8, 1980, abandoned.
US Referenced Citations (7)
Non-Patent Literature Citations (1)
Entry |
J. Polymer Science, vol. 46, pp. 75-89, 1960. |
Continuations (2)
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Number |
Date |
Country |
Parent |
313400 |
Oct 1981 |
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Parent |
119728 |
Feb 1980 |
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