US5851469A
Expired / Lapsed
US
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Process for making a wood-thermoplastic composite
Assignee: Trex Co Inc
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Filing: 1997-10-01
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Granted: 1998-12-22
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Expires: 2017-10-01
Abstract
Abstract The invention relates to a method for making a dimensionally stable wood-thermoplastic composite material composed of a wood component and a thermoplastic component comprising the steps of forming a wood-thermoplastic mass at a temperature above the melting temperature of the thermoplastic component. The mass is then passed through a converging die to form a shaped extrudate profile having a cross sectional shape wherein at least a part of the converging die is maintained at a substantially higher temperature than that of the mass. The profile is then fed through a low friction thermally insulating land section, the land section having the substantially the same cross sectional shape as the exit end of the converging die. The profile is then quenched in a non-oxidizing environment to form a substantially dimensionally stable outer shell around the profile, the shell having a temperature below the melting temperature of the thermoplastic component. The invention also relates to a die assembly for making a wood-thermoplastic composite material.
Inventors
- 👤 John J. Muller
- 👤 Roger A. Wittenberg
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 08:59
CPC Classifications
B; B27; B27N; B27N3/00; B27N3/08; B27N3/28; B29; B29C; B29C48/00; B29C48/03; B29C48/09; B29C48/12; B29C48/25; B29C48/88; B29C48/911; B29C48/94
Claims Analysis
Total Claims: 45
Claim 1
Independent Claim
124 words
A method for forming an extruded composite product containing cellulosic particles in a thermoplastic binder wherein an extrusion mass is forced through a die at an elevated extrusion temperature to form a hot shaped extrudate and cooled thereafter, said method including the steps of: (a) heating the extrusion mass in a die means to a first temperature sufficient to decrease the shear stresses generated between the mass and the die means to form a hot shaped extrudate profile; (b) passing the profile from the die through an intermediate temperature zone wherein the extrudate surface is thermally insulated from exterior cooling; and (c) quenching the profile directly in a non-oxidizing fluid to a second temperature thereby setting the composite surface to form the composite product.
Claim 2
Independent Claim
124 words
A method for forming an extruded composite product containing cellulosic particles in a thermoplastic binder wherein an extrusion mass is forced through a die at an elevated extrusion temperature to form a hot shaped extrudate and cooled thereafter, said method including the steps of: (a) heating the extrusion mass in a die means to a first temperature sufficient to decrease the shear stresses generated between the mass and the die means to form a hot shaped extrudate profile; (b) passing the profile from the die through an intermediate temperature zone wherein the extrudate surface is thermally insulated from exterior cooling; and (c) quenching the profile directly in a non-oxidizing fluid to a second temperature thereby setting the composite surface to form the composite product.
Claim 3
Dependent Claim
28 words
The method of claim 1 wherein the quenching step (c) further includes flowing said non-oxidizing quench fluid from the quenching step concurrently along the surface of the profile.
Claim 4
Dependent Claim
11 words
The method of claim 2 wherein the quench fluid is water.
Claim 5
Dependent Claim
14 words
The method of claim 1 wherein the die means is a converging die means.
Claim 6
Dependent Claim
26 words
The method of claim 4 wherein the converging die means is composed of a plurality of stages each of the stages provided with individual temperature control.
Claim 7
Dependent Claim
22 words
The method of claim 1 wherein the die means is a multi-opening die means capable of extruding at least two profiles simultaneously.
Claim 8
Dependent Claim
122 words
The method of claim 1 wherein the quenching step (c) is accomplished by contacting the profile with the quench fluid in a cooling means, the cooling means including: (i) a quench fluid inlet section having a passage therethrough, the passage adapted to receive the profile; (ii) at least one quench fluid channel disposed within the inlet section, the quench fluid channel extending radially from the inlet section passage; (iii) an enclosed flume secured to the quench fluid inlet section and having a flume passage therethrough, the flume passage having an interior surface, wherein the flume passage is in communication with the quench fluid inlet section passage; and (iv) a quench fluid annulus defined between the flume passage interior surface and the profile.
Claim 9
Dependent Claim
40 words
The method of claim 7 wherein the quenching step (c) takes place in an inlet section passage and a flume passage each having a larger and dissimilar cross-sectional shape than that of the profile exiting the low friction land section.
Claim 10
Dependent Claim
17 words
The method of claim 7 wherein the enclosed flume is comprised of at least two separable sections.
Claim 11
Dependent Claim
20 words
The method of claim 7 wherein the enclosed flume has a length of between about 4 feet to 7 feet.
Claim 12
Dependent Claim
22 words
The method of claim 7 wherein the cooling means further includes a means for controlling quench fluid flow into the cooling means.
Claim 13
Dependent Claim
30 words
The method of claim 7 wherein the enclosed cooling flume further includes a collar enclosing the profile exiting the flume and a quench fluid exit positioned upstream from the collar.
Claim 14
Dependent Claim
30 words
The method of claim 7 wherein the enclosed cooling flume further includes a collar enclosing the profile exiting the flume and a quench fluid inlet positioned upstream from the collar.
Claim 15
Dependent Claim
17 words
The method of claim 13 wherein the quench fluid flows countercurrent to the direction of the profile.
Claim 16
Dependent Claim
14 words
The method of claim 12 wherein the collar is comprised of a resilient material.
Claim 17
Dependent Claim
14 words
The method of claim 13 wherein the collar is comprised of a resilient material.
Claim 18
Dependent Claim
34 words
The method of claim 1 wherein the intermediate temperature zone is comprised of a low friction thermally insulating land section for preventing heat transfer between the heating step (a) and the quenching step (c).
Claim 19
Dependent Claim
122 words
In a method for forming an extruded composite product containing cellulosic particles in a thermoplastic binder wherein an extrusion mass is forced through a die at an elevated extrusion temperature to form a hot shaped extrudate and cooled thereafter, the improvement comprising: (a) heating the extrusion mass in a die means to a first temperature sufficient to decrease the shear stresses generated between the mass and the die means to form a hot shaped extrudate profile; (b) passing the profile from the die through an intermediate temperature zone wherein the extrudate surface is thermally insulated from exterior cooling; and (c) quenching the profile directly in a non-oxidizing fluid to a second temperature thereby setting the composite surface to form the composite product.
Claim 20
Dependent Claim
122 words
In a method for forming an extruded composite product containing cellulosic particles in a thermoplastic binder wherein an extrusion mass is forced through a die at an elevated extrusion temperature to form a hot shaped extrudate and cooled thereafter, the improvement comprising: (a) heating the extrusion mass in a die means to a first temperature sufficient to decrease the shear stresses generated between the mass and the die means to form a hot shaped extrudate profile; (b) passing the profile from the die through an intermediate temperature zone wherein the extrudate surface is thermally insulated from exterior cooling; and (c) quenching the profile directly in a non-oxidizing fluid to a second temperature thereby setting the composite surface to form the composite product.
Claim 21
Dependent Claim
20 words
The method of claim 18 wherein the quenching step (c) forms a substantially dimensionally stable outer shell around the profile.
Claim 22
Dependent Claim
22 words
The method of claim 19 wherein the dimensionally stable outer shell has a temperature below the melting temperature of the thermoplastic component.
Claim 23
Independent Claim
107 words
A method for making a dimensionally stable wood-thermoplastic composite material composed of a wood component and a thermoplastic component comprising the steps of: (a) forming a wood-thermoplastic mass, the mass being at a temperature above melting temperature of the thermoplastic component; (b) passing the mass through a converging die having an exit end to form a shaped extrudate profile having a cross sectional shape; (c) feeding the profile through a low friction thermally insulating land section, the land section having the substantially the same cross sectional shape as the converging die exit end; and (d) quenching the profile in a non-oxidizing environment to form a composite material.
Claim 24
Independent Claim
107 words
A method for making a dimensionally stable wood-thermoplastic composite material composed of a wood component and a thermoplastic component comprising the steps of: (a) forming a wood-thermoplastic mass, the mass being at a temperature above melting temperature of the thermoplastic component; (b) passing the mass through a converging die having an exit end to form a shaped extrudate profile having a cross sectional shape; (c) feeding the profile through a low friction thermally insulating land section, the land section having the substantially the same cross sectional shape as the converging die exit end; and (d) quenching the profile in a non-oxidizing environment to form a composite material.
Claim 25
Dependent Claim
20 words
The method of claim 21 wherein the quenching step (d) forms a substantially dimensionally stable outer shell around the profile.
Claim 26
Dependent Claim
22 words
The method of claim 22 wherein the dimensionally stable outer shell has a temperature below the melting temperature of the thermoplastic component.
Claim 27
Dependent Claim
122 words
The method of claim 21 wherein the quenching step (d) is accomplished by contacting the profile with a cooling medium in a cooling means, the cooling means including: (a) a cooling medium inlet section having a passage therethrough, the passage adapted to receive the profile; (b) at least one cooling medium channel disposed within the inlet section, the cooling medium channel extending radially from the inlet section passage; (c) an enclosed flume secured to the cooling medium inlet section and having a flume passage therethrough, the flume passage having an interior surface, wherein the flume passage is in communication with the cooling medium inlet section passage; and (d) a cooling medium annulus defined between the flume passage interior surface and the profile.
Claim 28
Dependent Claim
30 words
The method of claim 21 wherein step (b) takes place in a converging die means composed of a plurality of stages each of the stages provided with individual temperature control.
Claim 29
Dependent Claim
22 words
The method of claim 21 wherein the converging die has multiple openings to permit the extrusion of at least two profiles simultaneously.
Claim 30
Dependent Claim
40 words
The method of claim 21 wherein the wood-thermoplastic extrudate is provided at a temperature of about 330 to 350 degrees Fahrenheit and at least one stage of the converging die means is maintained at about 450 to 600 degrees Fahrenheit.
Claim 31
Dependent Claim
41 words
The method of claim 24 wherein the quenching step (d) takes place in an inlet section passage and a flume passage each having a larger and substantially similar cross-sectional shape than that of the profile exiting the low friction land section.
Claim 32
Dependent Claim
40 words
The method of claim 24 wherein the quenching step (d) takes place in an inlet section passage and a flume passage each having a larger and dissimilar cross-sectional shape than that of the profile exiting the low friction land section.
Claim 33
Dependent Claim
17 words
The method of claim 24 wherein the enclosed flume is comprised of at least two separable sections.
Claim 34
Dependent Claim
20 words
The method of claim 24 wherein the enclosed flume has a length of between about 4 feet to 7 feet.
Claim 35
Dependent Claim
22 words
The method of claim 24 wherein the cooling means further includes a means for controlling cooling medium flow into the cooling means.
Claim 36
Dependent Claim
30 words
The method of claim 24 wherein the enclosed cooling flume further includes a collar enclosing the profile exiting the flume and a cooling medium exit positioned upstream from the collar.
Claim 37
Dependent Claim
30 words
The method of claim 24 wherein the enclosed cooling flume further includes a collar enclosing the profile exiting the flume and a cooling medium inlet positioned upstream from the collar.
Claim 38
Dependent Claim
17 words
The method of claim 34 wherein the cooling medium flows countercurrent to the direction of the profile.
Claim 39
Independent Claim
112 words
A method for making a dimensionally stable wood-thermoplastic composite material composed of a wood component and a thermoplastic component comprising the steps of: (a) forming a wood-thermoplastic mass, the mass being at a temperature above melting temperature of the thermoplastic component; (b) passing the mass through converting die having an exit end to form a shaped extrudate profile having a cross sectional shape; (c) feeding the profile through a low friction thermally insulating land section, the land section having substantially the same cross sectional shape as the converging die exit end; and (d) quenching the profile in a non-oxidizing environment to form a composite material having a substantially dimensionally stable outer shell.
Claim 40
Independent Claim
112 words
A method for making a dimensionally stable wood-thermoplastic composite material composed of a wood component and a thermoplastic component comprising the steps of: (a) forming a wood-thermoplastic mass, the mass being at a temperature above melting temperature of the thermoplastic component; (b) passing the mass through converting die having an exit end to form a shaped extrudate profile having a cross sectional shape; (c) feeding the profile through a low friction thermally insulating land section, the land section having substantially the same cross sectional shape as the converging die exit end; and (d) quenching the profile in a non-oxidizing environment to form a composite material having a substantially dimensionally stable outer shell.
Claim 41
Dependent Claim
14 words
The method of claim 34 wherein the collar is comprised of a resilient material.
Claim 42
Independent Claim
114 words
A method for making a dimensionally stable wood-thermoplastic composite material composed of a wood component and a thermoplastic component comprising the steps of: (a) forming a wood-thermoplastic mass, the mass being at a temperature above melting temperature of the thermoplastic component; (b) passing the mass through a converging die having an exit end to form a shaped extrudate profile having a cross sectional shape; (c) feeding the profile through a low friction thermally insulating land section, the land section having the substantially the same cross sectional shape as the converging die exit end; and (d) quenching the profile in a non-oxidizing environment to form a composite material having a substantially dimensionally stable outer shell.
Claim 43
Independent Claim
114 words
A method for making a dimensionally stable wood-thermoplastic composite material composed of a wood component and a thermoplastic component comprising the steps of: (a) forming a wood-thermoplastic mass, the mass being at a temperature above melting temperature of the thermoplastic component; (b) passing the mass through a converging die having an exit end to form a shaped extrudate profile having a cross sectional shape; (c) feeding the profile through a low friction thermally insulating land section, the land section having the substantially the same cross sectional shape as the converging die exit end; and (d) quenching the profile in a non-oxidizing environment to form a composite material having a substantially dimensionally stable outer shell.
Claim 44
Dependent Claim
28 words
The method of claim 38 wherein the quenching step (d) forms a substantially dimensionally stable outer shell having a temperature below the melting temperature of the thermoplastic component.
Claim 45
Dependent Claim
21 words
The method of claim 38 wherein the substantially dimensionally stable outer shell extends to the core of the composite material profile.
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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) | 2001-12-21 | 2002-06-22 | 2002-12-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-12-21 | 2006-06-22 | 2006-12-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-12-21 | 2010-06-22 | 2010-12-22 | $7700.00 | Window Closed / Lapsed |