US4035329A
Expired / Lapsed
US
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Process for the continuous production of an ethylene/vinyl acetate copolymer dispersion
Assignee: Wacker Chemie AG
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Filing: 1975-11-19
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Granted: 1977-07-12
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Expires: 1995-11-19
Abstract
Abstract A process for the continuous manufacture of an aqueous ethylene/vinyl acetate copolymer dispersion which comprises continuously copolymerizing ethylene and vinyl acetate and optionally other α-olefinically unsaturated monomers, in an aqueous emulsion in the presence of an emulsifier and/or a protective colloid, and in the presence of a free-radical-forming redox catalyst system of a reducing agent and an oxidizing agent as well, optionally, as a heavy metal salt, and recovering said ethylene/vinyl acetate copolymer dispersion, characterized by (a) the presence of a molar excess of at least 3 times, preferably from 3 to 10 times, said reducing agent over said oxidizing agent dosed into the reaction medium and (b) adding the monomers continuously to the reaction mixture at such a rate that the concentration of unreacted monomers at no place in the reaction zone exceeds 15% by weight of the total weight of the reaction mixture.
Inventors
- 👤 Hubert Wiest
- 👤 Josef Hanzalik
- 👤 Wilhelm Lechner
- 👤 Erwin Lieb
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 11:47
CPC Classifications
C; C08; C08F; C08F218/00; C08F218/02; C08F218/04; C08F218/08; C08F210/00; C08F210/02
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
196 words
The process for the continuous manufacture of an aqueous ethylene/vinyl acetate copolymer dispersion, which comprises continuously adding a monomer mixture of ethylene and vinyl acetate containing up to 40% by weight of the share of the vinyl acetate of an α-olefinically unsaturated monomer copolymerizable with ethylene and vinyl acetate, in an aqueous emulsion containing emulsifiers and/or protective colloids, to a confined reaction zone, together with the continuous adding of a free-radical-forming water-soluble redox catalyst system comprising a reducing agent and an oxidizing agent and from 0 to 50 ppm, based on the total monomers, of a heavy metal in the form of a heavy metal salt, maintaining said confined reaction zone at a temperature sufficient to effect polymerization and continuously withdrawing an aqueous ethylene/vinyl acetate copolymer dispersion from said confined reaction zone, the improvement which consists of (a) continuously adding said reducing agent and said oxidizing agent in a molar ratio of at least 3:1 and (b) continuously adding said monomer mixture at such a rate that the concentration of unreacted monomers at no place in said confined reaction zone exceeds 15% by weight of the total weight of the reaction mixture in the reaction zone.
Claim 2
Dependent Claim
196 words
The process for the continuous manufacture of an aqueous ethylene/vinyl acetate copolymer dispersion, which comprises continuously adding a monomer mixture of ethylene and vinyl acetate containing up to 40% by weight of the share of the vinyl acetate of an α-olefinically unsaturated monomer copolymerizable with ethylene and vinyl acetate, in an aqueous emulsion containing emulsifiers and/or protective colloids, to a confined reaction zone, together with the continuous adding of a free-radical-forming water-soluble redox catalyst system comprising a reducing agent and an oxidizing agent and from 0 to 50 ppm, based on the total monomers, of a heavy metal in the form of a heavy metal salt, maintaining said confined reaction zone at a temperature sufficient to effect polymerization and continuously withdrawing an aqueous ethylene/vinyl acetate copolymer dispersion from said confined reaction zone, the improvement which consists of (a) continuously adding said reducing agent and said oxidizing agent in a molar ratio of at least 3:1 and (b) continuously adding said monomer mixture at such a rate that the concentration of unreacted monomers at no place in said confined reaction zone exceeds 15% by weight of the total weight of the reaction mixture in the reaction zone.
Claim 3
Dependent Claim
24 words
The process of claim 1, wherein said reducing agent and said oxidizing agent are added in a molar ratio of from 3:1 to 10:1.
Claim 4
Dependent Claim
35 words
The process of claim 1, wherein said concentration of unreacted monomers at no place in said confined reaction zone exceeds 10% by weight of the total weight of the reaction mixture in the reaction zone.
Claim 5
Dependent Claim
31 words
The process of claim 1 wherein said confined reaction zone prior to said continuous addition is substantially filled with a polymerized dispersion of the same recipe prepared by a batch process.
Claim 6
Dependent Claim
31 words
The process of claim 1 wherein said aqueous ethylene/vinyl acetate copolymer dispersion being continuously withdrawn from said confined reaction zone has a solids content of from 40% to 65% by weight.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-07-11 | 1981-01-10 | 1981-07-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-07-11 | 1985-01-10 | 1985-07-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-07-11 | 1989-01-10 | 1989-07-12 | $7700.00 | Window Closed / Lapsed |