Diene-based rubber latex, method for preparing thereof and graft copolymer with core-shell structure comprising the same

Patent metadata

Field	Value
Publication number	US-11932709-B2
Application number	US-201917051720-A
Country	US
Kind code	B2
Filing date	Dec 17, 2019
Priority date	Dec 20, 2018
Publication date	Mar 19, 2024
Grant date	Mar 19, 2024

Abstract

The present invention relates to a diene-based rubber latex including a polymer aggregate and having an extra large diameter, a method for preparing same and a graft copolymer with a core-shell structure, including same and having excellent impact strength and surface properties. A diene-based rubber latex of which 14 wt % to 26 wt % has diameter of 100 nm to less than 300 nm, 62 wt % to 81 wt % has a diameter of 300 nm to less than 800 nm, and 5 wt % to 14 wt % has a diameter of 800 nm to less than 1000 nm, based on 100 wt % of total rubber particles.

First claim

The invention claimed is:

1. A diene-based rubber latex, wherein 14 wt % to 26 wt % of rubber particles in the latex have a diameter of 100 nm to less than 300 nm, 62 wt % to 81 wt % of the rubber particles have a diameter of 300 nm to less than 800 nm, and 5 wt % to 14 wt % of the rubber particles have a diameter of 800 nm to less than 1000 nm, based on 100 wt % of total rubber particles.

2. The diene-based rubber latex of claim 1 , wherein a roundness of the rubber particles as defined by the following Mathematical Formula 1 is from 1.05 to 1.10:

Roundness
=

1

5
⁢
0

⁢

∑

i
=
1

50

D
i

[

Mathematical
⁢

Formula
⁢

1

]

in Mathematical Formula 1, D i is a ratio of a length of a major axis with respect to a length of a minor axis [length of major axis/length of minor axis] for an i-th particle in latex.

3. The diene-based rubber latex of claim 1 , wherein the diene-based rubber latex is enlarged by a polymer aggregate with an average particle diameter of 230 nm to 300 nm, the polymer aggregate comprising a unit derived from an unsaturated carboxylic acid or an ester monomer thereof and a unit derived from a comonomer having a functional group.

4. The diene-based rubber latex of claim 3 , wherein the polymer aggregate comprises 85 wt % to 92 wt % of the unit derived from an unsaturated carboxylic acid or an ester monomer thereof and 8 wt % to 15 wt % of the unit derived from a comonomer having a functional group.

5. The diene-based rubber latex of claim 3 , wherein the unsaturated carboxylic acid or the ester monomer thereof is one or more selected from the group consisting of methyl methacrylate, ethyl methacrylate, butyl methacrylate, methyl acrylate, ethyl acrylate, acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, maleic anhydride, monobutyl fumarate, monobutyl maleate and mono-2-hydroxypropyl maleate.

6. The diene-based rubber latex of claim 3 , wherein the comonomer having a functional group is methacrylamide, acrylamide or a combination thereof.

7. The diene-based rubber latex of claim 1 , wherein the diene-based rubber latex comprises a solid coagulate moiety of 0.01 wt % or less.

8. A method for preparing the diene-based rubber latex of claim 1 , the method comprising:
a) polymerizing a first conjugated diene-based monomer in the presence of an emulsifier and a fat-soluble polymerization initiator to prepare a first polymerization product of a polymerization conversion ratio of 30% to 40%;
b) injecting a water-soluble polymerization initiator into the first polymerization product and elevating a temperature to prepare a second polymerization product of a polymerization conversion ratio of 60% to 70%;
c) injecting a second conjugated diene-based monomer into the second polymerization product and polymerizing to prepare a third polymerization product of a polymerization conversion ratio of 85% to 93%; and
d) injecting a polymer aggregate with an average particle diameter of 230 nm to 300 nm and a water-soluble polymerization initiator into the third polymerization product and polymerizing,
wherein the first conjugated diene-based monomer and the second conjugated diene-based monomer are used in a weight ratio of 80 to 95:5 to 20, and
the polymer aggregate is injected in 0.01 parts by weight to 1.50 parts by weight based on 100 parts by weight of a total amount of the first conjugated diene-based monomer and the second conjugated diene-based monomer.

9. The method for preparing the diene-based rubber latex of claim 8 , wherein the polymer aggregate is prepared by emulsion polymerization comprising:
i) polymerizing 20 to 40 parts by weight of an unsaturated carboxylic acid or an ester monomer thereof in the presence of 0.1 to 0.2 parts by weight of a crosslinking agent; and
ii) injecting and polymerizing 50 to 75 parts by weight of the unsaturated carboxylic acid or the ester monomer thereof and 5 parts by weight to 10 parts by weight of the comonomer having a functional group at a point where a polymerization conversion ratio of the step i) is 85 to 95%, based on 100 parts by weight of a total amount of the unsaturated carboxylic acid or the ester monomer thereof and the comonomer having a functional group.

10. The method for preparing the diene-based rubber latex of claim 9 , wherein the crosslinking agent is one or more selected from the group consisting of ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, aryl methacrylate and 1,3-butylene glycol diacrylate.

11. The method for preparing the diene-based rubber latex of claim 8 , wherein the elevating of the temperature in the step b) is to a temperature increased by 15° C. to 25° C. with respect to a temperature during the first polymerization.

12. The method for preparing the diene-based rubber latex of claim 8 , wherein the first conjugated diene-based monomer and the second conjugated diene-based monomer are one or more selected from the group consisting of 1,3-butadiene, isoprene, chloroprene and piperylene.

13. A graft copolymer with a core-shell structure, the graft copolymer comprising:
a rubbery polymer core;
and a shell wrapping the core and comprising a unit derived from an aromatic vinyl-based monomer and a unit derived from a vinyl cyan-based monomer,
wherein the rubbery polymer core comprises
from 3 parts by weight to 5 parts by weight of the diene-based rubber latex of claim 1 , wherein the diene-based rubber latex of claim 1 has an average diameter of 600 nm to 800 nm,
and from 95 parts by weight to 97 parts by weight of a diene-based rubber latex with an average diameter of 310 nm to 330 nm based on 100 parts by weight of the core.

14. The graft copolymer with a core-shell structure of claim 13 , wherein the copolymer comprises 40 wt % to 60 wt % of the core; and 40 wt % to 60 wt % of the shell, and
the shell comprises the unit derived from an aromatic vinyl-based monomer and the unit derived from a vinyl cyan-based monomer in a weight ratio of 3:1 to 2:1.

15. The graft copolymer with a core-shell structure of claim 13 , wherein the copolymer has a solid coagulate moiety content of 0.03 wt % or less.

Assignees

• Lg Chemical Ltd

Inventors

• Bak Chang Hong
• Jeong Young Hwan
• Kim Young Min

Classifications

• C08C1/07 Primary

  characterised by the agglomerating agents used · CPC title

• C08C1/065

  Increasing the size of dispersed rubber particles · CPC title

• C08F6/18

  Increasing the size of the dispersed particles · CPC title

• C08F236/04 Primary

  conjugated · CPC title

• C08F236/06

  Butadiene · CPC title