Method of preparing vinyl cyanide compound-conjugated diene rubber-aromatic vinyl compound graft copolymer and method of preparing thermoplastic resin composition including the same

Patent metadata

Field	Value
Publication number	US-12441827-B2
Application number	US-202117913250-A
Country	US
Kind code	B2
Filing date	Aug 19, 2021
Priority date	Oct 23, 2020
Publication date	Oct 14, 2025
Grant date	Oct 14, 2025

Abstract

Disclosed is a method of preparing a vinyl cyanide compound-conjugated diene rubber-aromatic vinyl compound graft copolymer and a method of preparing a thermoplastic resin composition including the same. Also disclosed is a conjugated diene rubber latex having an average particle diameter of 2,400 to 2,800 Å added to enlarged conjugated diene rubber latex obtained by enlarging conjugated diene rubber latex having an average particle diameter of 2,400 to 2,800 Å using a polymer coagulant to prepare bimodal conjugated diene rubber, and a vinyl cyanide compound-conjugated diene rubber-aromatic vinyl compound graft copolymer prepared by graft-polymerizing the bimodal conjugated diene rubber.

First claim

The invention claimed is:

1. A method of preparing a vinyl cyanide compound-conjugated diene rubber-aromatic vinyl compound graft copolymer, comprising:
step (a) comprising adding a polymer coagulant to a medium-diameter conjugated diene rubber latex having an average particle diameter of 2,400 to 2,800 Å to enlarge the medium-diameter conjugated diene rubber latex to prepare a large-diameter conjugated diene rubber latex having an average particle diameter of 5,800 to 8,500 Å;
step (b) comprising adding a medium-diameter conjugated diene rubber latex having an average particle diameter of 2,400 to 2,800 Å to the prepared large-diameter conjugated diene rubber latex to prepare a bimodal conjugated diene rubber latex; and
step (c) comprising graft-polymerizing the prepared bimodal conjugated diene rubber latex, an aromatic vinyl compound, and a vinyl cyanide compound to obtain a vinyl cyanide compound-conjugated diene rubber-aromatic vinyl compound graft copolymer.

2. The method according to claim 1 , wherein, in step (a), the polymer coagulant is added in an amount of 0.3 to 1.5 parts by weight of solids based on 100 parts by weight of solids of the medium-diameter conjugated diene rubber latex.

3. The method according to claim 1 , wherein the polymer coagulant has an average particle diameter of 700 to 1,700 Å.

4. The method according to claim 1 , wherein the polymer coagulant is a graft copolymer prepared by graft-polymerizing an alkyl acrylate compound and a carboxylic acid-based compound onto a core obtained by polymerizing one or more selected from the group consisting of alkyl acrylate compounds and carboxylic acid-based compounds.

5. The method according to claim 1 , wherein, in step (a), the polymer coagulant is continuously added at a constant rate for 5 to 20 minutes while stirring the medium-diameter conjugated diene rubber latex at 200 to 300 rpm, and aging is performed for 10 to 30 minutes.

6. The method according to claim 1 , wherein step (a) comprises performing stabilization by adding an emulsifier after performing enlarging to obtain the large-diameter conjugated diene rubber latex.

7. The method according to claim 1 , wherein, in step (a), the medium-diameter conjugated diene rubber latex is prepared by steps comprising adding an emulsifier, an electrolyte, a molecular weight modifier, and an initiator to 60 to 80 parts by weight of 100 parts by weight of a conjugated diene compound and performing primary polymerization;
adding 20 to 40 parts by weight of the conjugated diene compound when polymerization conversion rate is 30 to 40% after the primary polymerization step and performing secondary polymerization;
adding an initiator and a molecular weight modifier when polymerization conversion rate is 55 to 65% after the secondary polymerization step and performing tertiary polymerization;
adding a redox initiator when polymerization conversion rate is 75 to 85% after the tertiary polymerization step and performing quaternary polymerization; and
terminating polymerization when polymerization conversion rate is 93 to 99% after the quaternary polymerization step.

8. The method according to claim 1 , wherein, in step (b), 85 to 96% by weight of solids of the medium-diameter conjugated diene rubber latex having an average particle diameter of 2,400 to 2,800 Å is added to 4 to 15% by weight of solids of the large-diameter conjugated diene rubber latex to prepare the bimodal conjugated diene rubber latex.

9. A method of preparing a thermoplastic resin composition, comprising:
preparing the vinyl cyanide compound-conjugated diene rubber-aromatic vinyl compound graft copolymer according to claim 1 ; and
feeding 15 to 40% by weight of the prepared graft copolymer and 60 to 85% by weight of an aromatic vinyl compound-vinyl cyanide compound copolymer into an extruder, performing melt-kneading and performing extrusion.

10. A thermoplastic resin composition, comprising 15 to 40% by weight of a graft copolymer comprising a bimodal conjugated diene rubber, an aromatic vinyl compound, and a vinyl cyanide compound and 60 to 85% by weight of an aromatic vinyl compound-vinyl cyanide compound copolymer,
wherein the bimodal conjugated diene rubber comprises, based on a total weight thereof, 85 to 97% by weight of conjugated diene rubber having an average particle diameter of 2,400 to 2,800 Å, 1 to 14% by weight of conjugated diene rubber having an average particle diameter of 5,800 to 8,500 Å, and 0.1 to 2% by weight of a polymer coagulant, and the thermoplastic resin composition has an Izod impact strength of 32 kgf cm/cm or more as measured using a specimen having a thickness of ¼″ according to ASTM D256.

11. The thermoplastic resin composition according to claim 10 , wherein the bimodal conjugated diene rubber has an average particle diameter of 3,000 to 3,800 Å.

12. The thermoplastic resin composition according to claim 10 , wherein the graft copolymer has a grafting degree of 30 to 45%.

13. The thermoplastic resin composition according to claim 10 , wherein the thermoplastic resin composition has a melt index of 20 g/10 min or more as measured under conditions of 220° C. and 10 kg according to ASTM D1238.

Assignees

• Lg Chemical Ltd

Inventors

• Jung Yu Sung
• Chai Joo Byung
• Kim Jong Beom
• Jeon Taeyoung
• Kim In Seok

Classifications

• C08L2205/18

  Spheres · CPC title

• C08L2205/025

  containing two or more polymers of the same hierarchy C08L, and differing only in parameters such as density, comonomer content, molecular weight, structure · CPC title

• C08L2201/52

  Aqueous emulsion or latex, e.g. containing polymers of a glass transition temperature (Tg) below 20°C · CPC title

• C08L55/02

  ABS [Acrylonitrile-Butadiene-Styrene] polymers · CPC title

• C08F6/22

  Coagulation · CPC title