Multi-stage polymer as a grinding additive and a method of producing the same

Patent metadata

Field	Value
Publication number	US-9546267-B2
Application number	US-201214420384-A
Country	US
Kind code	B2
Filing date	Sep 17, 2012
Priority date	Sep 17, 2012
Publication date	Jan 17, 2017
Grant date	Jan 17, 2017

Abstract

This invention generally relates to a multi-stage polymer as a grinding additive and a method of producing the same.

First claim

The invention claimed is:

1. A multi-stage polymer comprising, based on the total weight of the multi-stage polymer, from 1 wt. % to 99 wt. % of a first stage polymer, and from 1 wt. % to 99 wt. % of a second stage polymer,
wherein the first stage polymer comprises, as polymerization units, based on the total weight of the first stage polymer:
(a) from 2 wt. % to 20 wt. %, of a nonionic macromonomer, characterized by the following formula: H 2 C═C(R)CO 2 (CH 2 CH 2 O) n (CH(R′)CH 2 O) m R″, wherein R is H or CH 3 , R′ is C 1 -C 2 alkyl; R″ is C 8 -C 30 alkyl, C 8 -C 16 alkylphenyl or C 13 -C 36 aralkylphenyl; n is an integral number from 6 to 100 and m is an integral number from 0 to 50, provided that n≧m and m+n is from 6 to 100;
(b) from 35 wt. % to 60 wt. %, of an α,β-ethylenically unsaturated carboxylic acid monomer; and
(c) from 35 wt. % to 60 wt. %, of an α,β-ethylenically unsaturated nonionic monomer;
wherein the first stage polymer has a weight average molecular weight of at least 50,000 Daltons; and
the second stage polymer comprises, as polymerization units, based on the total weight of the second stage polymer:
(e) from 10 wt. % to 70 wt. %, of an α,β-ethylenically unsaturated carboxylic acid monomer; and
(f) from 30 wt. % to 90 wt. %, of a nonionic α,β-ethylenically unsaturated monomer;
wherein the second stage polymer has a weight average molecular weight of from 500 to 20,000 Daltons, and the second stage polymer contains a substantial absence of the nonionic macromonomer.

2. The multi-stage polymer according to claim 1 , wherein the first stage polymer further comprises, as polymerization units, based on the total weight of the first stage polymer, from 0.01 wt. % to 5 wt. %, a polyethyenically unsaturated crosslinking monomer.

3. The multi-stage polymer according to claim 1 , wherein the second stage polymer contains an absence of the nonionic macromonomer.

4. The multi-stage polymer according to claim 1 , wherein the α,β-ethylenically unsaturated carboxylic acid monomer is acrylic acid, methacrylic acid or a combination thereof.

5. The multi-stage polymer according to claim 1 , wherein the (α,β-ethylenically unsaturated nonionic monomer is ethyl acrylate, methyl methacrylate, 2-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, vinyl acetate or acrylonitrile or a combination thereof.

6. A method for preparing a multi-stage polymer which comprises the steps:
i) contacting under emulsion polymerization conditions a first monomer composition comprising:
(a) from 2 wt. % to 20 wt. %, of a nonionic macromonomer, characterized by the following formula: H 2 C═C(R)CO 2 (CH 2 CH 2 O) n (CH(R′)CH 2 O) m R″, wherein R is H or CH 3 , R′ is C 1 -C 2 alkyl; R″ is C 8 -C 30 alkyl, C 8 -C 16 alkylphenyl or C 13 -C 36 aralkylphenyl; n is an integral number from 6 to 100 and m is an integral number from 0 to 50, provided that n≧m and m+n is from 6 to 100;
(b) from 35 wt. % to 60 wt. %, of an α,β-ethylenically unsaturated carboxylic acid monomer; and
(c) from 35 wt. % to 60 wt. %, of an α,β-ethylenically unsaturated nonionic monomer; to obtain a first stage polymer having a weight average molecular weight of at least 50,000 Daltons; and

ii) contacting under emulsion polymerization the first stage polymer with a second monomer composition comprising, based on the weight of the second monomer composition:
(e) from 10 wt. % to 70 wt. %, of an α,β-ethylenically unsaturated carboxylic acid monomer; and
(f) from 30 wt. % to 90 wt. %, of an α,β-ethylenically unsaturated nonionic monomer; to obtain a second stage polymer having a weight average molecular weight of from 500 to 20,000 Daltons, and the second stage polymer contains a substantial absence of the nonionic macromonomer.

7. The method for preparing a multi-stage polymer according to claim 6 , wherein the first monomer composition further comprises, based on the total weight of the first polymer composition, from 0.01 wt. % to 5 wt. %, a polyethyenically unsaturated crosslinking monomer.

8. The method for preparing a multi-stage polymer according to claim 6 , wherein the second monomer composition contains an absence of the nonionic macromonomer.

9. The method for preparing a multi-stage polymer according to claim 6 , wherein the α,β-ethylenically unsaturated carboxylic acid monomer is acrylic acid or methacrylic acid or a combination thereof.

10. The method for preparing a multi-stage polymer according to claim 6 , wherein the α,β-ethylenically unsaturated nonionic monomer is ethyl acrylate, methyl methacrylate, 2-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, vinyl acetate or acrylonitrile or a combination thereof.

11. A coating composition comprising from 0.1% to 2%, by weight based on the total weight of the coating composition, of the multi-stage polymer according to claim 1 , a pigment, an extender, and a binder.

Assignees

• Rohm & Haas

Inventors

• Li Ling

Classifications

• C08F265/04

  on to polymers of esters · CPC title

• C09D151/003

  grafted on to macromolecular compounds obtained by reactions only involving unsaturated carbon-to-carbon bonds (C09D151/04, C09D151/06 take precedence) · CPC title

• C08F220/288

  and containing polypropylene-co-ethylene oxide in the alcohol moiety · CPC title

• C08F265/02

  on to polymers of acids, salts or anhydrides · CPC title

• C08F290/062

  Polyethers · CPC title