Gradient copolymers for use in automatic dishwashing systems

Patent metadata

Field	Value
Publication number	US-11292992-B2
Application number	US-201816753908-A
Country	US
Kind code	B2
Filing date	Oct 9, 2018
Priority date	Oct 23, 2017
Publication date	Apr 5, 2022
Grant date	Apr 5, 2022

Abstract

A polymer comprising a first fraction and a second fraction, wherein the first fraction comprises from 90 to 100 wt % polymerized C 3 -C 6 carboxylic acid monomer units; and the second fraction comprises from 30 to 80 wt % polymerized C 3 -C 6 carboxylic acid monomer units and from 20 to 70 wt % polymerized sulfonic acid monomer units; wherein the first fraction is from 10 to 40 wt % of the polymer and the second fraction is from 60 to 90 wt % of the polymer; the polymer has M w from 3,000 to 30,000; and monomers are randomly distributed within each fraction.

First claim

The invention claimed is:

1. A method for producing a random copolymer; said method comprising steps of: (a) polymerizing a first monomer composition comprising from 90 to 100 wt % C 3 -C 6 carboxylic acid monomer in an initial polymerization phase; and (b) polymerizing a second monomer composition comprising from 30 to 80 wt % C 3 -C 6 carboxylic acid monomer and from 20 to 70 wt % sulfonic acid monomer in a second polymerization phase; wherein a chain transfer agent is added during addition of the first and second monomer compositions; and wherein the chain transfer agent is added with monomers continuously over the entire monomer addition time.

2. The method of claim 1 in which the sulfonic acid monomers are selected from the group consisting of 2-acrylamido-2-methylpropane sulfonic acid, vinyl sulfonic acid, 2-sulfoethyl acrylate, 2-sulfoethyl methacrylate, sulfopropyl acrylate, sulfopropyl methacrylate, styrene sulfonic acid, 3-allyloxy-2-hydroxy-1-propanesulfonic acid, and 2-propene-1-sulfonic acid, and salts thereof, and combinations thereof.

3. The method of claim 2 in which the first monomer composition comprises from 95 to 100 wt % (meth)acrylic acid; and the second monomer composition comprises from 40 to 70 wt % (meth)acrylic acid and from 30 to 60 wt % sulfonic acid monomer.

4. The method of claim 3 in which the first monomer composition is from 13 to 32 wt % of total monomers and the second monomer composition is from 68 to 87 wt % of total monomers.

5. The method of claim 4 in which free radical polymerization initiator is added in an amount from 0.1 to 5 wt % of the total mass of the first and second monomer compositions, and at least 50 wt % of the initiator is added continuously with the monomers.

6. The method of claim 1 , wherein the chain transfer agent is selected from the group consisting of sodium metabisulfite, sodium hypophosphite, phosphorous acid, 2-mercaptoethanol, 3-mercaptopropionic acid and 1-dodecanethiol.

Assignees

• Dow Global Technologies Llc
• Rohm & Haas

Inventors

• Creamer Marianne
• Ferrieux Severine
• Wasserman Eric

Classifications

• C11D3/08

  Silicates · CPC title

• C11D3/361

  Phosphonates, phosphinates or phosphonites · CPC title

• C11D3/3788

  Graft polymers · CPC title

• C11D1/66

  Non-ionic compounds {(C11D1/002, C11D1/004, C11D1/008 take precedence)} · CPC title

• C11D3/3757

  (Co)polymerised carboxylic acids, -anhydrides, -esters in solid and liquid compositions · CPC title