Patent US4374791A successfully refreshed from Google Patents.
US4374791A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for preparing particleboard
Assignee: Dow Chemical Co
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Filing: 1981-09-28
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Granted: 1983-02-22
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Expires: 2001-09-28
Abstract
Abstract Particle boards are currently prepared by treating the particles (e.g. wood chips) with a binder comprising an organic polyisocyanate and an internal release agent and then subjecting the treated particles to a forming process involving heat and pressure. While the resulting particle board will generally release well from the caul plates of the press after forming, due to the effect of the internal release agent, it has been found that the ease of release is enhanced by precoating the surfaces of the caul plates or platens which come into contact with the particle board with a layer of polytetrafluoroethylene which layer optionally contains an internal release agent.
Inventors
- 👤 William J. Farrissey
- 👤 Alexander McLaughlin
- 👤 Douglas P. Waszeciak
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 11:05
CPC Classifications
B; B29; B29C; B29C33/00; B29C33/56; B29C33/60; B29C33/62; B27; B27N; B27N3/00; B27N3/08; B27N3/083
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
91 words
In a process for the preparation of particle board wherein particles of material capable of being compacted are contacted with a polyisocyanate binder containing an internal release agent and the treated particles are subsequently formed into boards by the application of heat and pressure utilizing metal caul plates or platens, the imporvement which comprises enhancing the release of the finished particle board from the metallic surfaces which come into contact with said particle board during said application of heat and pressure, by precoating said metallic surfaces with a layer of polytetrafluoroethylene.
Claim 2
Dependent Claim
91 words
In a process for the preparation of particle board wherein particles of material capable of being compacted are contacted with a polyisocyanate binder containing an internal release agent and the treated particles are subsequently formed into boards by the application of heat and pressure utilizing metal caul plates or platens, the imporvement which comprises enhancing the release of the finished particle board from the metallic surfaces which come into contact with said particle board during said application of heat and pressure, by precoating said metallic surfaces with a layer of polytetrafluoroethylene.
Claim 3
Dependent Claim
22 words
An improved process in accordance with claim 1 wherein the layer of polytetrafluoroethylene is applied in the form of an aerosol spray.
Claim 4
Dependent Claim
22 words
An improved process in accordance with claim 1 wherein the layer of polytetrafluoroethylene is applied in the form of an aqueous dispersion.
Claim 5
Dependent Claim
19 words
An improved process in accordance with claim 1 wherein the precoating of said metallic surfaces is achieved by sintering.
Claim 6
Dependent Claim
27 words
An improved process in accordance with claim 1 wherein the precoating of said metallic surface is achieved by covering said surface with a preformed film of polytetrafluoroethylene.
Claim 7
Dependent Claim
32 words
An improved process according to claim 1 wherein the metallic surfaces which are coated are surfaces of steel selected from the class consisting of cold-rolled steel, hot rolled steel, and stainless steel.
Claim 8
Dependent Claim
18 words
An improved process according to claim 1 wherein a release agent is incorporated in the layer of polytetrafluoroethylene.
Claim 9
Dependent Claim
24 words
An improved process according to claim 7 wherein the release agent is the pyrophosphate derived from a mixture of lauryl mono- and di-acid phosphates.
References Cited (Backward Citations)
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US4064208A
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US4257995A
Cited
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Cited
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US4258169A
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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) | 1986-02-21 | 1986-08-23 | 1987-02-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-02-21 | 1990-08-23 | 1991-02-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-02-21 | 1994-08-23 | 1995-02-22 | $7700.00 | Window Closed / Lapsed |