US4021413A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Production of wood glue
Assignee: BASF SE
•
Filing: 1974-07-02
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Granted: 1977-05-03
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Expires: 1994-07-02
Abstract
Abstract Condensates containing urea and formaldehyde in a molar ratio of from 1:2.5 to 1:4.5 are converted into wood glue by allowing the viscosity to increase at a pH of from 1 to 3 and at only slightly elevated temperature and then adding urea at a pH of 7 to 9.
Inventors
- 👤 Wolfgang Eisele
- 👤 Harro Petersen
- 👤 Johann Mayer
- 👤 Otto Wittmann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 02:43
CPC Classifications
C; C08; C08G; C08G12/00; C08G12/02; C08G12/04; C08G12/10; C08G12/12; C09; C09J; C09J161/00; C09J161/20; C09J161/22; C09J161/24
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
148 words
A process for the production of a wood glue by acid treatment of an aqueous precondensate of formaldehyde and urea having a formaldehyde content of at least 2.5 moles per mole of urea followed by addition of urea up to a formaldehyde content of less than 2 moles per mole of urea, wherein the precondensate which has a condensate content of from 40 to 70% based on the weight of the solution, and a molar ratio of formaldehyde to urea of from 2.5:1 to 4.5:1 is acidified to a pH of from 1 to 3 and allowed to stand at a temperature of from ambient temperature to 40° C. until the solution has a viscosity of 5,000 to 150,000 centipoises/20° C., the pH is then adjusted to from 7 to 9 and urea is added until a molar ratio of urea:formaldehyde of 1:1.2 to 1:2 has been reached.
Claim 2
Dependent Claim
148 words
A process for the production of a wood glue by acid treatment of an aqueous precondensate of formaldehyde and urea having a formaldehyde content of at least 2.5 moles per mole of urea followed by addition of urea up to a formaldehyde content of less than 2 moles per mole of urea, wherein the precondensate which has a condensate content of from 40 to 70% based on the weight of the solution, and a molar ratio of formaldehyde to urea of from 2.5:1 to 4.5:1 is acidified to a pH of from 1 to 3 and allowed to stand at a temperature of from ambient temperature to 40° C. until the solution has a viscosity of 5,000 to 150,000 centipoises/20° C., the pH is then adjusted to from 7 to 9 and urea is added until a molar ratio of urea:formaldehyde of 1:1.2 to 1:2 has been reached.
Claim 3
Dependent Claim
21 words
A process as set forth in claim 1 wherein the precondensate is allowed to stand at pH from 1.5 to 2.5.
Claim 4
Dependent Claim
22 words
A process as set forth in claim 1 wherein the precondensate has a molar ratio of formaldehyde:urea of from 3.5:1 to 4:1.
Claim 5
Dependent Claim
20 words
A process as set forth in claim 1, wherein the precondensate has a formaldehyde content of from 45 to 55%.
References Cited (Backward Citations)
DE1168882B
Cited
US3450659A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-05-02 | 1980-11-01 | 1981-05-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-05-02 | 1984-11-01 | 1985-05-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-05-02 | 1988-11-01 | 1989-05-03 | $7700.00 | Window Closed / Lapsed |