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Patent US4051214A successfully refreshed from Google Patents.
US4051214A
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Method of controlling monomer loss during the production of a fiber-thermoplastic matrix by in situ bulk polymerization
Assignee: Weyerhaeuser Co
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Filing: 1977-01-14
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Granted: 1977-09-27
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Expires: 1997-01-14
Abstract
Abstract An improved method of controlling monomer loss during the production of a fiber-thermoplastic matrix by in situ bulk polymerization is described, the improvement allowing polymerization to greater than 25% polymer content by weight of the matrix within less than eight minutes. A fibrous web of less than 0.25-inch thickness, saturated with a liquid phase polymerizable composition containing a vinyl monomer and a thermally activated free radical initiator at 1/2-10% by weight of the composition is polymerized under controlled conditions in which the matrix is: (a) confined between heat transfer surfaces at 0.2-20 psig; (b) heated to a temperature sufficient to initiate polymerization but below the boiling point of the composition; (c) increased in temperature as the boiling point of the composition increases during polymerization while still maintaining the temperature below the boiling point of the composition; and (d) increased in temperature above the boiling point of the composition when the desired polymer content is obtained in order to evaporate residual monomer from the matrix. The resulting matrix is suitable for molding by the application pressure into useful products.
Inventors
- 👤 Richard R. Casper
- 👤 Myron P. Marander
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 10:15
CPC Classifications
B; B29; B29C; B29C70/00; B29C70/04; B29C70/06; B29C70/10; B29C70/16; B29C70/22
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
162 words
In a method for making a moldable, fiber-thermoplastic matrix by in situ bulk polymerization wherein a fibrous web of less than 0.25 inch thickness is impregnated with a liquid polymerizable composition, comprising a monomer and a thermally activated free radical initiator wherein the matrix after polymerization contains at least 25% polymer by weight and said bulk polymerization is completed in less than 8 minutes, the improvement whereby monomer loss is controlled during polymerization, which comprises: confining the impregnated web matrix between heat transfer surfaces wherein the matrix is subjected to a pressure of 0.2 to 20 psig; heating the impregnated matrix to an initial temperature sufficient to initiate polymerization but below the boiling point of the polymerizable composition; raising the temperature as the boiling point of the composition increases during polymerization while still maintaining the temperature below said boiling point; and increasing the temperature above the boiling point when polymerization is nearly complete in order to evaporate residual monomer from the composition.
Claim 2
Dependent Claim
162 words
In a method for making a moldable, fiber-thermoplastic matrix by in situ bulk polymerization wherein a fibrous web of less than 0.25 inch thickness is impregnated with a liquid polymerizable composition, comprising a monomer and a thermally activated free radical initiator wherein the matrix after polymerization contains at least 25% polymer by weight and said bulk polymerization is completed in less than 8 minutes, the improvement whereby monomer loss is controlled during polymerization, which comprises: confining the impregnated web matrix between heat transfer surfaces wherein the matrix is subjected to a pressure of 0.2 to 20 psig; heating the impregnated matrix to an initial temperature sufficient to initiate polymerization but below the boiling point of the polymerizable composition; raising the temperature as the boiling point of the composition increases during polymerization while still maintaining the temperature below said boiling point; and increasing the temperature above the boiling point when polymerization is nearly complete in order to evaporate residual monomer from the composition.
Claim 3
Dependent Claim
35 words
The method of claim 1, wherein heating the matrix to an initial temperature, raising the matrix temperature during polymerization and increasing its temperature above the residual monomer boiling point, comprises: controlling said temperatures step wise.
Claim 4
Dependent Claim
62 words
The method of claim 2, wherein controlling said temperatures step wise, comprises: controlling said temperatures between 240° F and 320° F, while maintaining said temperature at least 5° F below the boiling point of the polymerizable composition until at least 25% polymer by weight of the matrix is attained; and increasing thereupon said temperature above the boiling point of the remaining composition.
Claim 5
Dependent Claim
57 words
The method of claim 3, wherein said impregnated matrix comprises a cellulosic web impregnated with a monomer selected from the group consisting of styrene, di-chlorostyrene, acrylonitrile, divinyl benzene, and esters of acrylic and methacrylic acids, the alcohol portions of said esters containing from 1 to 18 carbon atoms and 0.5-10% of a thermally activated free radical initiator.
Claim 6
Dependent Claim
169 words
In a method for making a moldable, fiber-thermoplastic matrix by in situ bulk polymerization wherein a cellulosic web of less than 0.25 inch thickness and of basis weight less than 600 lbs. per ream is impregnated with a liquid polymerizable composition comprising styrene monomer and a thermally activated free radical initiator of 0.5-10% of said composition wherein the matrix after polymerization contains at least 25% polymer by weight and said bulk polymerization is completed in less than 8 minutes, the improvement whereby monomer loss is controlled during polymerization which comprises: confining the impregnated web matrix between heat transfer surfaces wherein the matrix is subjected to a pressure of 0.2-20 psig; heating the impregnated matrix to an initial temperature of 225°-285° F to initiate polymerization but below the boiling point of the polymerizable composition; removing heat from the matrix to maintain the temperature at 225°-285° F until said matrix contains at least 25% polymer; and increasing said matrix temperature to 320°-350° F to evaporate excess monomer and complete the polymerization.
Claim 7
Dependent Claim
169 words
In a method for making a moldable, fiber-thermoplastic matrix by in situ bulk polymerization wherein a cellulosic web of less than 0.25 inch thickness and of basis weight less than 600 lbs. per ream is impregnated with a liquid polymerizable composition comprising styrene monomer and a thermally activated free radical initiator of 0.5-10% of said composition wherein the matrix after polymerization contains at least 25% polymer by weight and said bulk polymerization is completed in less than 8 minutes, the improvement whereby monomer loss is controlled during polymerization which comprises: confining the impregnated web matrix between heat transfer surfaces wherein the matrix is subjected to a pressure of 0.2-20 psig; heating the impregnated matrix to an initial temperature of 225°-285° F to initiate polymerization but below the boiling point of the polymerizable composition; removing heat from the matrix to maintain the temperature at 225°-285° F until said matrix contains at least 25% polymer; and increasing said matrix temperature to 320°-350° F to evaporate excess monomer and complete the polymerization.
Claim 8
Dependent Claim
26 words
The method of claim 5, wherein heating to initiate polymerization, removing heat during polymerization and increasing heat to complete polymerization of the matrix is controlled step-wise.
Claim 9
Dependent Claim
18 words
The method of claim 6, wherein the steps are at 225° F, 265° F and 295° F, respectively.
Claim 10
Dependent Claim
18 words
The method of claim 6, wherein the steps are at 245° F, 265° F and 295° F, respectively.
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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) | 1980-09-26 | 1981-03-28 | 1981-09-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-09-26 | 1985-03-28 | 1985-09-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-09-26 | 1989-03-28 | 1989-09-27 | $7700.00 | Window Closed / Lapsed |