US5658431A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for preventing yellowing of lignocellulosic products
Assignee: Keskuslaboratorio Centrallaboratorium Oy AB
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Filing: 1995-04-20
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Granted: 1997-08-19
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Expires: 2015-04-20
Abstract
Abstract The invention relates to a method for protecting lignocellulosic material against yellowing caused by light or heat. The invention further concerns brightness stabilizing compositions intended for treatment of lignocellulosic materials. According to the invention, polytetrahydrofuran (PTHF) is used as the brightness stabilizing agent. Preferably PTHF having a molar mass of about 150 to 1500 is used. The invention provides a good stabilization of lignocellulosic pulp and of products containing such pulp, whereby the amount of PTHF required can be extremely small, e.g., 0.05-5% of the weight of the material.
Inventors
- 👤 Jan Janson
- 👤 Ingegerd Forsskåhl
- 👤 Taina Korhonen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 22:28
CPC Classifications
D; D21; D21H; D21H17/00; D21H17/20; D21H17/33; D21H17/46; D21H17/53; D21H21/00; D21H21/14; D21H21/143
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
62 words
A method for protecting mechanical pulp material or chemi-mechanical pulp material against yellowing, comprising: applying a brightness stabilizing agent to said material in an amount effective to increase a resistance to yellowing of the material; wherein said brightness stabilizing agent comprises polytetrahydrofuran and said effective amount is 0.05 to 5% by weight of the polytetrahydrofuran based on the weight of the material.
Claim 2
Independent Claim
62 words
A method for protecting mechanical pulp material or chemi-mechanical pulp material against yellowing, comprising: applying a brightness stabilizing agent to said material in an amount effective to increase a resistance to yellowing of the material; wherein said brightness stabilizing agent comprises polytetrahydrofuran and said effective amount is 0.05 to 5% by weight of the polytetrahydrofuran based on the weight of the material.
Claim 3
Dependent Claim
19 words
The method according to claim 1, wherein said polytetrahydrofuran has a molar mass of about 150 to about 1500.
Claim 4
Dependent Claim
24 words
The method according to claim 1, wherein said material is in a form selected from the group consisting of paper pulp, paper and board.
Claim 5
Dependent Claim
28 words
The method according to claim 1, wherein polytetrahydrofuran is applied by means of a surface treatment selected from the group consisting of surface sizing, spraying and pigment coating.
Claim 6
Dependent Claim
55 words
The method according to claim 4, wherein polytetrahydrofuran is applied in the form of a water dispersion or solution containing about 1 to about 40% of PTHF of the total weight of the dispersion or solution and said solution further comprises at least one member of the group consisting of dispersing agents and viscosity-increasing agents.
Claim 7
Dependent Claim
43 words
The method according to claim 4, wherein polytetrahydro-furan is applied-in the form of a coating mix containing pigments and binding agents, whereby the content of polytetrahydrofuran in the coating mix amounts to about 1 to about 40% of the weight of the pigment.
Claim 8
Dependent Claim
12 words
The method according to claim 1, wherein polytetrahydrofuran is applied by impregnation.
Claim 9
Dependent Claim
13 words
The method according to claim 1, wherein polytetrahydrofuran is admixed into pulp stock.
Claim 10
Dependent Claim
33 words
The method according to claim 1, comprising treating the material by impregnation and further comprising applying polytetrahydrofuran in an amount of 0.5 to 2.5 by weight based on the weight of the material.
Claim 11
Dependent Claim
36 words
The method according to claim 1, comprising treating the material by surface sizing or coating and further comprising applying polytetrahydrofuran in an amount of 0.2 to 3.0% by weight based on the weight of the material.
Claim 12
Dependent Claim
16 words
The method according claim 1, wherein polytetrahydrofuran is applied in combination with other brightness stabilizing agents.
Claim 13
Dependent Claim
15 words
The method according to claim 11, wherein polytetrahydro-furan is applied in combination with polyethylene glycol.
Claim 14
Dependent Claim
18 words
The method according to claim 8, further comprising applying polyethylene glycol onto the surface of the paper pulp.
Claim 15
Dependent Claim
30 words
A lignin-containing, uncoated paper, comprising a sheet of a mechanical pulp or chemi-mechanical pulp and containing 0.05 to 5%, calculated on basis of the weight of the paper, of polytetrahydrofuran.
Claim 16
Dependent Claim
30 words
A lignin-containing, uncoated paper, comprising a sheet of a mechanical pulp or chemi-mechanical pulp and containing 0.05 to 5%, calculated on basis of the weight of the paper, of polytetrahydrofuran.
References Cited (Backward Citations)
US3674632A
Cited
US4474919A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-08-18 | 2001-02-17 | 2001-08-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-08-18 | 2005-02-17 | 2005-08-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-08-18 | 2009-02-17 | 2009-08-19 | $7700.00 | Window Closed / Lapsed |