US5441602A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the prevention of scale formation in wood pulp production
Assignee: FMC Corp
•
Filing: 1993-08-18
•
Granted: 1995-08-15
•
Expires: 2013-08-18
Abstract
Abstract Hydrolyzed copolymers of (A) maleic anhydride with (B) at least one mono-ethylenically unsaturated monomer other than acrylic acid or methacrylic acid or with a mixture of (B) and (C) acrylic acid or methacrylic acid are effective for inhibiting the formation of calcium carbonate scale in wood pulp production.
Inventors
- 👤 Arthur Harris
- 👤 John Burrows
- 👤 David Wilson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 09:57
CPC Classifications
D; D21; D21C; D21C3/00; D21C3/22; D21C3/226; Y; Y10; Y10S; Y10S162/00; Y10S162/04
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
68 words
An improved process for inhibiting the formation of calcium carbonate scale in wood pulp production wherein the improvement comprises. adding to a white liquor used to extract lignin from wood 1-100 ppm of a hydrolysed copolymer of (A) maleic anhydride with (B) at least one mono-ethylenically unsaturated monomer other than acrylic acid or methacrylic acid, or with a mixture of (B) and (C) acrylic acid or methacrylic acid.
Claim 2
Dependent Claim
68 words
An improved process for inhibiting the formation of calcium carbonate scale in wood pulp production wherein the improvement comprises. adding to a white liquor used to extract lignin from wood 1-100 ppm of a hydrolysed copolymer of (A) maleic anhydride with (B) at least one mono-ethylenically unsaturated monomer other than acrylic acid or methacrylic acid, or with a mixture of (B) and (C) acrylic acid or methacrylic acid.
Claim 3
Dependent Claim
23 words
A process as claimed in claim 1, in which the molar ratio of maleic anhydride to other monomer(s) is from 1:100 to 100:1.
Claim 4
Dependent Claim
16 words
A process as claimed in claim 2, in which the molar ratio is at least 1:1.
Claim 5
Dependent Claim
17 words
A process as claimed in claim 2, in which the molar ratio is from 1:3 to 30:1.
Claim 6
Dependent Claim
17 words
A process as claimed in claim 4, in which the molar ratio is from 2.5:1 to 7:1.
Claim 7
Dependent Claim
50 words
A process as claimed in claim 1, in which the ethylenically unsaturated monomer (B) is selected from crotonic acid, itaconic acid, aconitic acid, esters of said acids, esters of acrylic acid or methacrylic acid, acrylonitrile, acrylamide, vinyl acetate, styrene, α-methyl styrene, methyl vinyl ketone, acrolein, ethylene, propylene or mixtures thereof.
Claim 8
Dependent Claim
22 words
A process as claimed in claim 1, in which the copolymer is a terpolymer derived from maleic anhydride and two other monomers.
Claim 9
Dependent Claim
60 words
A process as claimed in claim 1, in which the copolymer is a copolymer of maleic anhydride with at least one mono-ethylenically unsaturated acid, or an ester, amide or water-soluble salt thereof; or a copolymer of maleic anhydride with at least one mono-ethylenically unsaturated acid, or an ester, amide or water-soluble salt thereof, and at least one mono-ethylenically unsaturated hydrocarbon.
Claim 10
Dependent Claim
70 words
A process according to claim 8, in which the copolymer is a copolymer of maleic anhydride with an allylic acid or allylic ester; a copolymer of maleic anhydride with an acrylic amide; a copolymer of maleic anhydride with an acrylic amide and a vinyl carboxylate; or a copolymer of maleic anhydride with an ester of a mono-ethylenically unsaturated acid and either a mono-ethylenically unsaturated acid or a mono-ethylenically unsaturated hydrocarbon.
Claim 11
Dependent Claim
65 words
A process according to claim 9, in which the copolymer is a copolymer of maleic anhydride with allylsulfonic acid; a copolymer of maleic anhydride with N,N-dimethylacrylamide; a copolymer of maleic anhydride, the sodium salt of acrylamidomethylpropane sulfonic acid and vinyl acetate; or a copolymer of maleic anhydride with (i) an alkyl acrylate or alkyl methacrylate and (ii) acrylic acid, methacrylic acid or an aliphatic olefin.
Claim 12
Dependent Claim
53 words
A process as claimed in claim 1, in which the copolymer is a terpolymer derived from maleic anhydride and two ethylenically unsaturated monomers selected from acrylic acid, methacrylic acid, crotonic acid, itaconic acid, aconitic acid, esters of said acids, acrylonitrile, acrylamide, vinyl acetate, styrene, α-methyl styrene, methyl vinyl ketone, acrolein, ethylene and propylene.
Claim 13
Dependent Claim
24 words
A process as claimed in claim 11, in which the molar ratio of said two monomers to each other is from 1:3 to 3:1.
Claim 14
Dependent Claim
16 words
A process as claimed in claim 12, in which the ratio is from 1:2 to 2:1.
Claim 15
Dependent Claim
22 words
A process as claimed in claim 11, in which the terpolymer is a terpolymer of maleic anhydride, ethyl acrylate and vinyl acetate.
Claim 16
Dependent Claim
27 words
A process as claimed in claim 14, in which the molar ratio of maleic anhydride to combined vinyl acetate and ethyl acrylate is from 2.5:1 to 5:1.
Claim 17
Dependent Claim
23 words
A process as claimed in claim 14, in which the molar ratio of vinyl acetate to ethyl acrylate is from 1:3 to 3:1.
Claim 18
Dependent Claim
16 words
A process as claimed in claim 16, in which the ratio is from 1:2 to 2:1.
Claim 19
Dependent Claim
18 words
A process as claimed in claim 14, in which the molecular weight of terpolymer is up to 1000.
Claim 20
Dependent Claim
17 words
A process as claimed in claim 1, in which the copolymer is added to recycled white liquor.
Claim 21
Dependent Claim
18 words
A process as in claim 1 wherein the pH of the white liquor is between 12 and 14.
Claim 22
Dependent Claim
20 words
A process as in claim 1 wherein the temperature of the white liquor is between 150° C. and 175° C.
Claim 23
Dependent Claim
32 words
A process as in claim 1 wherein the pH of the white liquor is between 12 and 14, and the temperature of the white liquor is between 150° C. and 175° C.
Claim 24
Dependent Claim
14 words
A process as in claim 22 wherein the white liquor is recycled white liquor.
References Cited (Backward Citations)
GB1113644A
Cited
US3929635A
Cited
US4126549A
Cited
US4049546A
Cited
JPS60212681A
Cited
JPS61140582A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-08-14 | 1999-02-13 | 1999-08-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-08-14 | 2003-02-13 | 2003-08-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-08-14 | 2007-02-13 | 2007-08-15 | $7700.00 | Window Closed / Lapsed |