METHOD FOR PREPARING GRAFT RUBBER LATEX HAVING LOW RESIDUAL MONOMER CONTENT

• US 20070123657A1
• Filed: 10/03/2006
• Published: 05/31/2007
• Est. Priority Date: 10/04/2005
• Status: Active Grant

• Current Assignee: LG Chem Limited (LG Corporation)
• Original Assignee: LG Chem Limited (LG Corporation)
• Inventors: LEE, Jin-hyoung, CHAI, Joo-byung, JUNG, Jae-hwan, YOO, Keun-hoon, LEE, Chan-hong
• Granted Patent: US 7,897,686 B2
• Time in Patent Office: Days
• US Class Current: 525/242
• CPC Class Codes: C08F 279/02 on to polymers of conjugated dienes

Abstract

The present invention relates to a method for preparing a graft rubber latex having a low residual monomer content, and more precisely, a method for preparing a graft rubber latex having a high rubber content, which is characterized by graft-copolymerization of a mixture of a rubber latex having a gel content of at least 95% and an average particle diameter of 2,500˜5000 Å, a monomer mixture comprising one or more compounds selected from a group consisting of aromatic vinyl compound, vinyl cyan compound and acrylate compound, and small particle size latex produced by emulsion polymerization. The method of the present invention has the advantages of speedy processes with excellent latex stability and at the same time reducing residual monomer content in the latex upon completion of the polymerization, improving perceived quality of the product and increasing yield.

Claims

1. A method for preparing a graft rubber latex having low residual monomer content, which is characterized by graft copolymerization of

(a) 50˜

70 weight part of rubber latex having a gel content of at least 95% and an average particle diameter of 2,500˜

5,000 Å

;

(b) 30˜

50 weight part of a monomer mixture composed of one or more compounds selected from a group consisting of aromatic vinyl compound, vinyl cyan compound and acrylate compound; and

(c) 1˜

20 weight part of a small particle size latex.

2. The method for preparing the graft rubber latex having low residual monomer content according to claim 1, wherein the rubber latex of (a) is one or more compounds selected from a group consisting of polybutadiene, butadiene-styrene copolymer, butadiene-alkylacrylate copolymer, polyisoprene and polychloroprene.

3. The method for preparing the graft rubber latex having low residual monomer content according to claim 1, wherein the rubber latex of (a) is a large particle size rubber latex prepared by enlarging the small particle size rubber latex particles in the presence of an acid.

4. The method for preparing the graft rubber latex having low residual monomer content according to claim 1, wherein the molar ratio of the rubber latex of (a) to the monomer mixture of (b) is 20:

80˜

40;

60.

5. The method for preparing the graft rubber latex having low residual monomer content according to claim 1, wherein the small particle size latex of (c) is prepared by emulsion polymerization with one or more compounds selected from a group consisting of aromatic vinyl compound, vinyl cyan compound and acrylate compound.

6. The method for preparing the graft rubber latex having low residual monomer content according to claim 1, wherein the small particle size latex of (c) has an average particle diameter of 20˜

100 nm.

7. The method for preparing the graft rubber latex having low residual monomer content according to claim 1, wherein the step of adding a redox polymerization initiator is additionally included when the polymerization conversion rate reaches at least 94%.

8. The method for preparing the graft rubber latex having low residual monomer content according to claim 7, wherein the redox polymerization initiator is one or more compounds selected from a group consisting of cumenehydro peroxide, diisopropyl benzenehydro peroxide, azobis isobutylnitrile, 3^rd grade butylhydro peroxide, paramethanehydro peroxide and benzoil peroxide.

9. The method for preparing the graft rubber latex having low residual monomer content according to claim 7, wherein the redox polymerization initiator is added as a bundle twice at 30 minute intervals or continuously for 1˜

2 hours from when the polymerization conversion rate reaches at least 94%.

10. The method for preparing the graft rubber latex having low residual monomer content according to claim 1, wherein the reaction time to give the graft rubber latex having low residual monomer content is up to 3 hours.

11. The method for preparing the graft rubber latex having low residual monomer content according to claim 1, wherein the residual monomer content is up to 5,000 ppm.

12. A graft rubber latex having a residual monomer content of up to 5,000 ppm, which is prepared by the method of claim 1.

13. A graft rubber latex having a residual monomer content of up to 5,000 ppm, which is prepared by the method of claim 6.

14. A graft rubber latex having a residual monomer content of up to 5,000 ppm, which is prepared by the method of claim 7.