US4238438A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hardboard with smooth, dense surface and method
Assignee: US PLYWOOD Corp A CORP OF
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Filing: 1979-02-01
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Granted: 1980-12-09
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Expires: 1999-02-01
Abstract
Abstract Disclosed is a hardboard with a smooth, highly-consolidated, dense surface and a method for making it. The method of this invention greatly reduces the need for surface sanding after molding because release from the molding caul is improved and results in a product having a surface more free of defects. According to a preferred embodiment, a dry mat of wood particles is sprayed with from 8 to 30 grams per square foot of a surface coating of a consolidating agent comprising from 50 to 95% water, from 4 to 25% ethylene glycol and from 1 to 25% polyvinyl acetate, prior to pressing at elevated temperature. These percentages are based on the weight of the consolidating agent. The preferred products will have at least one highly-consolidated, smooth surface layer which comprises from 0.5 to 4 grams of polyhydric alcohol and from 0.5 to 4 grams of polyvinyl acetate per square foot of surface.
Inventors
- 👤 Gerald F. Laughinghouse
- 👤 Donald B. Gibson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 16:53
CPC Classifications
C; C08; C08L; C08L97/00; C08L97/02
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
147 words
A dry formed method for making hardboard with a smooth, dense surface which comprises: (a) mixing fibers with a thermosetting glue system; (b) forming a mat of said fibers having a moisture content less than 30%; (c) applying to the surface fibers of said mat from 8 to 30 grams per square foot of a coating of a surface consolidating agent comprising from 62 to 95% water, from 4 to 25% of a hydroxy-radical-containing compound having a boiling point of from 212° F. to 600° F. selected from the group consisting of alcohols and their esters, and from 1 to 25% polyvinyl acetate, wherein the percentages of ingredients are based on the weight of the surface consolidating agent; and (d) pressing said mat for a time and at a temperature and pressure effective to consolidate the fibers and permanently bind them by virtue of the glue system.
Claim 2
Dependent Claim
147 words
A dry formed method for making hardboard with a smooth, dense surface which comprises: (a) mixing fibers with a thermosetting glue system; (b) forming a mat of said fibers having a moisture content less than 30%; (c) applying to the surface fibers of said mat from 8 to 30 grams per square foot of a coating of a surface consolidating agent comprising from 62 to 95% water, from 4 to 25% of a hydroxy-radical-containing compound having a boiling point of from 212° F. to 600° F. selected from the group consisting of alcohols and their esters, and from 1 to 25% polyvinyl acetate, wherein the percentages of ingredients are based on the weight of the surface consolidating agent; and (d) pressing said mat for a time and at a temperature and pressure effective to consolidate the fibers and permanently bind them by virtue of the glue system.
Claim 3
Dependent Claim
14 words
A method according to claim 1 wherein the hydroxy-radical-containing compound is a polyhydric alcohol.
Claim 4
Dependent Claim
46 words
A method according to claim 1 wherein the mat is pressed at a temperature in the range of about 200° F. to about 600° F., at a pressure of about atmospheric to about 1000 psi and for a time period of up to about 10 minutes.
Claim 5
Dependent Claim
28 words
A method according to claim 1 wherein the glue system is mixed in an amount of from 0.5 to 10% based on the dry weight of the fibers.
Claim 6
Dependent Claim
31 words
A method according to claim 1 wherein the glue system comprises a member selected from the class consisting of phenol formaldehyde resin, urea formaldehyde resin, melamine formaldehyde resin and combinations thereof.
Claim 7
Dependent Claim
78 words
A method according to claim 1 wherein the glue system comprises a phenol formaldehyde resin in an amount of from about 2 to 6% based on the dry weight of the fibers; the hydroxyl group-containing compound comprises ethylene glycol; and the mat is pressed at a temperature in the range of about 200° F. to about 600° F., at a pressure of about atmospheric to about 1000 psi for a time period of up to about 10 minutes.
Claim 8
Dependent Claim
48 words
A method according to claim 6 wherein the surface consolidating agent is applied to the mat in an amount of from 8 to 30 grams per square foot of surface and comprises from 50 to 95% water, from 4-25% polyhydric alcohol, and from 1 to 25% polyvinyl acetate.
Claim 9
Dependent Claim
34 words
A method according to claim 7 wherein the mat is pressed with a caul having a molding surface which is configured to apply a wood grain configuration to the surface of the finished panel.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-12-09 | 1984-06-09 | 1984-12-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-12-09 | 1988-06-09 | 1988-12-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-12-09 | 1992-06-09 | 1992-12-09 | $7700.00 | Window Closed / Lapsed |