Patent US4174310A successfully refreshed from Google Patents.
US4174310A
Expired / Lapsed
US
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Process for producing aqueous urea-formaldehyde
Assignee: Imperial Chemical Industries Ltd
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Filing: 1977-06-20
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Granted: 1979-11-13
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Expires: 1997-06-20
Abstract
Abstract Aqueous urea-formaldehyde resins solutions are prepared by (a) forming a first aqueous solution containing urea and formaldehyde in a molecular ratio in the range urea:formaldehyde=1:3 to 1:1.5, (b) reacting the first aqueous solution under neutral or alkaline conditions to form a reaction mixture containing substantial amounts of methylol urea products, (c) vacuum evaporating the reaction mixture to produce a concentrated mixture having a solids content of 55% to 80% by weight, and (d) further condensing the concentrated mixture under acid conditions to produce a resinous material. The urea may be wholly or partially replaced by melamine.
Inventors
- 👤 Donald A. Hubbard
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 15:48
CPC Classifications
C; C08; C08G; C08G12/00; C08G12/02; C08G12/04; C08G12/10; C08G12/12; C08G12/26; C08G12/30; C08G12/32; C08G12/34; C08G12/36; C08G12/38
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
117 words
A process for producing aqueous urea- and/or melamine-formaldehyde resin solutions which comprises the steps of: (a) forming a first reaction mixture containing substantial amounts of methylol urea and/or methylol melamine products by condensing, under neutral or alkaline conditions, reactants comprising urea and/or melamine and formalin in the form of an aqueous formalin solution (35% to 45% w/w) in a molecular ratio within the range urea and/or melamine:formaldehyde=1:3 to urea and/or melamine:formaldehyde=1:1.5; (b) vacuum evaporating the reaction mixture to form a concentrated mixture having a solids content of 55% to 80% by weight, and (c) with no further addition of formaldehyde to the concentrated mixture further condensing the concentrated mixture under acid conditions to produce a resinous material.
Claim 2
Dependent Claim
117 words
A process for producing aqueous urea- and/or melamine-formaldehyde resin solutions which comprises the steps of: (a) forming a first reaction mixture containing substantial amounts of methylol urea and/or methylol melamine products by condensing, under neutral or alkaline conditions, reactants comprising urea and/or melamine and formalin in the form of an aqueous formalin solution (35% to 45% w/w) in a molecular ratio within the range urea and/or melamine:formaldehyde=1:3 to urea and/or melamine:formaldehyde=1:1.5; (b) vacuum evaporating the reaction mixture to form a concentrated mixture having a solids content of 55% to 80% by weight, and (c) with no further addition of formaldehyde to the concentrated mixture further condensing the concentrated mixture under acid conditions to produce a resinous material.
Claim 3
Dependent Claim
30 words
A process as claimed in claim 1, wherein the amounts of methylol urea and/or methylol melamine products in the reaction mixture comprise upwards from 80% by weight of the reactants.
Claim 4
Dependent Claim
52 words
A process as claimed in claim 1, wherein the composition of the reaction mixuture is adjusted before vacuum evaporating by the addition thereto of urea and/or melamine or formaldehyde in the form of an aqueous formalin solution containing of formaldehyde, in an amount of less than 10% by weight of the reactants.
Claim 5
Dependent Claim
23 words
A process as claimed in claim 1, wherein the reaction mixture is formed by condensation for 12 to 36 hours at ambient temperature.
Claim 6
Dependent Claim
20 words
A process as claimed in claim 1, wherein the reaction mixture is formed by condensation for 10 to 60 minutes.
Claim 7
Dependent Claim
23 words
A process as claimed in claim 1, wherein the concentrated mixture is further condensed under acid conditions between pH 4.5 to pH 6.5.
Claim 8
Dependent Claim
25 words
A process as claimed in claim 6, wherein the further condensation is carried out by heating at 70° C. to 100° C. at atmospheric pressure.
Claim 9
Dependent Claim
25 words
A process as claimed in claim 6, wherein the further condensation is carried out by heating at above 100° C. and at above atmospheric pressure.
Claim 10
Dependent Claim
29 words
Process as claimed in claim 6, wherein after the said further condensation the product is cooled and its pH is adjusted to a pH value of at least 7.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-11-12 | 1983-05-14 | 1983-11-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-11-12 | 1987-05-14 | 1987-11-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-11-12 | 1991-05-14 | 1991-11-13 | $7700.00 | Window Closed / Lapsed |