US-12624139-B2 - Emulsion polymer and process for preparing the same

Abstract

An emulsion polymer comprising: (a) structural units of a specific polymerizable surfactant, (b) structural units of an ethylenically unsaturated anionic monomer, and (c) structural units of an ethylenically unsaturated nonionic monomer; wherein polymer segments of the emulsion polymer that comprise structural units of the ethylenically unsaturated anionic monomer and structural units of the ethylenically unsaturated nonionic monomer together have specific Hansen solubility parameters. An aqueous coating composition comprising such emulsion polymer provides good early water blister resistance.

Inventors

• Daoshu Lin
• Yan Wu
• Changkun Piao
• Jia Tang
• Dong Yun
• Hua Ren
• Zhenwen Fu
• Baoqing Zheng

Assignees

• DOW GLOBAL TECHNOLOGIES LLC
• ROHM AND HAAS COMPANY

Dates

Publication Date

20260512

Application Date

20200925

Claims (9)

1. 1 . An emulsion polymer comprising: (a) structural units of a polymerizable surfactant having the structure of formula (I), wherein R 1 is a phenyl group or where R is an alkylene group; m1 is 1, 2, 3 or 4; R 2 is an alkyl or a substituted alkyl; m2 is 0 or 1; A represents an alkylene group or a substituted alkylene group, having 2 to 4 carbon atoms; n is an integer in the range of from 1 to 30; and X represents —(CH 2 ) a —SO 3 M or —(CH 2 ) b —COOM, where a and b are each independently an integer of from 0 to 4, and M is an aminium ion having one ethylenically unsaturated bond; (b) structural units of an ethylenically unsaturated anionic monomer; and (c) structural units of an ethylenically unsaturated nonionic monomer; wherein polymer segments that comprise structural units of the ethylenically unsaturated anionic monomer and polymer segments that comprise structural units of the ethylenically unsaturated nonionic monomer together have the following Hansen solubility parameters: 16.42≤δ D ≤16.64, 2.87≤δ P ≤3.79, and 3.94≤δ H ≤4.57.
2. 2 . The emulsion polymer of claim 1 , wherein, in formula (I), R 1 is and m 1 is 2 or 3.
3. 3 . The emulsion polymer of claim 1 , wherein, in formula (I), A represents —CH 2 CH 2 —, and X represents —SO 3 M, where M is
4. 4 . The emulsion polymer of claim 1 , wherein the ethylenically unsaturated nonionic monomer is selected from the group consisting of styrene, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, cyclohexyl methacrylate, or mixtures thereof.
5. 5 . The emulsion polymer of claim 1 , wherein the emulsion polymer comprises, by weight based on the weight of the emulsion polymer, from 0.5% to 3% of the polymerizable surfactant.
6. 6 . The emulsion polymer of claim 1 , comprising, by weight based on the weight of the emulsion polymer, structural units of the polymerizable surfactant having the structure of: where m1 is 2 or 3, and n is an integer in the range of from 1 to 30; structural units of the ethylenically unsaturated anionic monomer; from 30% to 50% of structural units of styrene; from 35% to 45% of structural units of butyl acrylate; and structural units of cyclohexyl methacrylate, methyl methacrylate, or mixtures thereof.
7. 7 . The emulsion polymer of claim 1 , comprising, by weight based on the weight of the emulsion polymer, structural units of the polymerizable surfactant having the structure of where m1 is 2 or 3, and n is an integer in the range of from 1 to 30; structural units of the ethylenically unsaturated anionic monomer; from 30% to 40% of structural units of styrene; from 30% to 39.5% of structural units of 2-ethyl hexyl acrylate; and structural units of cyclohexyl methacrylate, methyl methacrylate, or mixtures thereof.
8. 8 . A process for preparing the emulsion polymer of claim 1 , comprising: emulsion polymerization of a monomer mixture comprising an ethylenically unsaturated anionic monomer and an ethylenically unsaturated nonionic monomer in the presence of a polymerizable surfactant, wherein the polymerizable surfactant has the structure of formula (I), wherein R 1 is a phenyl group or where R is an alkylene group; m1 is 1, 2, 3 or 4; R 2 is an alkyl or a substituted alkyl; m2 is 0 or 1; A represents an alkylene group or a substituted alkylene group, having 2 to 4 carbon atoms; n is an integer in the range of from 1 to 30; and X represents —(CH 2 ) a —SO 3 M or —(CH 2 ) b —COOM, where a and b are each independently an integer of from 0 to 4, and M is an aminium ion having one ethylenically unsaturated bond; wherein polymer segments that comprise structural units of the ethylenically unsaturated anionic monomer and polymer segments that comprise structural units of the ethylenically unsaturated nonionic monomer together have the following Hansen solubility parameters: 16.42≤δ D ≤16.64, 2.87≤δ P ≤3.79, and 3.94≤δ H ≤4.57.
9. 9 . An aqueous coating composition comprising the emulsion polymer of claim 1 .

Description

FIELD OF THE INVENTION The present invention relates to an emulsion polymer and a process for preparing the same. INTRODUCTION Aqueous or waterborne coating compositions are widely used in industrial coating applications, for example, as exterior topcoats in freight container coatings (FCC). Water resistance, especially early water blister resistance, is typically required for exterior coatings in areas of southern China. After spraying topcoat compositions and drying at 60 to 80 degrees Celsius (° C.) for a period of time, some coated freight containers are dried at warehouse, while others are moved to outdoor for drying in the air. For drying the coated containers outdoor, it requires the resultant topcoats with sufficient early water blister resistance to avoid blisters caused by the rain, as blisters also have negative impacts on appearance and anti-corrosion performance of the coated freight containers. Therefore, it is desirable to provide a polymer, particularly suitable for coatings, that is capable of providing coatings with early water blister resistance. SUMMARY OF THE INVENTION The present invention provides a novel emulsion polymer particularly suitable for coating applications without the aforementioned problems. The emulsion polymer prepared in the presence of a specific polymerizable surfactant comprises polymer segments with specific Hansen solubility parameters. An aqueous coating composition comprising the emulsion polymer of the present invention can provide coatings with excellent early water blister resistance rated as 10, according to the test method described in the Examples section below. In a first aspect, the present invention is an emulsion polymer comprising: (a) structural units of a polymerizable surfactant having the structure of formula (I), wherein R1 is a phenyl group or where R is an alkylene group; m1 is 1, 2, 3 or 4; R2 is an alkyl or a substituted alkyl; m2 is 0 or 1; A represents an alkylene group or a substituted alkylene group, having 2 to 4 carbon atoms; n is an integer in the range of from 1 to 30; and X represents —(CH2)a—SO3M or —(CH2)b—COOM, where a and b are each independently an integer of from 0 to 4, and M is an aminium ion having one ethylenically unsaturated bond; (b) structural units of an ethylenically unsaturated anionic monomer; and(c) structural units of an ethylenically unsaturated nonionic monomer;wherein polymer segments that comprise structural units of the ethylenically unsaturated anionic monomer and polymer segments that comprise structural units of the ethylenically unsaturated nonionic monomer together have the following Hansen solubility parameters: 16.42⩽δ⁢D⩽16.64,2.87⩽δ⁢P⩽3.79,and 3.94⩽δ⁢H⩽4.57. In a second aspect, the present invention is a process of preparing the emulsion polymer of the first aspect. The process comprises: emulsion polymerization of a monomer mixture comprising an ethylenically unsaturated anionic monomer and an ethylenically unsaturated nonionic monomer in the presence of a polymerizable surfactant, wherein the polymerizable surfactant has the structure of formula (I), wherein R1 is a phenyl group or where R is an alkylene group; m1 is 1, 2, 3 or 4; R2 is an alkyl or a substituted alkyl; m2 is 0 or 1; A represents an alkylene group or a substituted alkylene group, having 2 to 4 carbon atoms; n is an integer in the range of from 1 to 30; and X represents —(CH2)a—SO3M or —(CH2)b—COOM, where a and b are each independently an integer of from 0 to 4, and M is an aminium ion having one ethylenically unsaturated bond;wherein polymer segments that comprise structural units of the ethylenically unsaturated anionic monomer and polymer segments that comprise structural units of the ethylenically unsaturated nonionic monomer together have the following Hansen solubility parameters: 16.42⩽δ⁢D⩽16.64,2.87⩽δ⁢P⩽3.79,and 3.94⩽δ⁢H⩽4.57. In a third aspect, the present invention is an aqueous coating composition comprising the emulsion polymer of the first aspect. DETAILED DESCRIPTION OF THE INVENTION “Aqueous” dispersion or composition herein means that particles dispersed in an aqueous medium. By “aqueous medium” herein is meant water and from 0 to 30%, by weight based on the weight of the medium, of water-miscible compound(s) such as, for example, alcohols, glycols, glycol ethers, glycol esters, and the like. “Acrylic” as used herein includes (meth)acrylic acid, alkyl (meth)acrylate, (meth)acrylamide, (meth)acrylonitrile and their modified forms such as hydroxyalkyl (meth)acrylate. Throughout this document, the word fragment “(meth)acryl” refers to both “methacryl” and “acryl”. For example, (meth)acrylic acid refers to both methacrylic acid and acrylic acid, and methyl (meth)acrylate refers to both methyl methacrylate and methyl acrylate. “Structural units”, also known as “polymerized units”, of the named monomer, refers to the remnant of the monomer after polymerization, that is, polymerized monomer or the monomer in polymerized f