US4466998A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Wood impregnation
Assignee: Hickson Corp
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Filing: 1982-06-16
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Granted: 1984-08-21
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Expires: 2002-06-16
Abstract
Abstract Water-borne preservative salts are used to impregnate wood by the empty-cell pressure impregnation method without the precipitation of water-borne salts such as chromium, copper and arsenic when wood sugars enter the treating solution during the kickback or pressure release phase of the empty-cell cycle. The lack of precipitation is obtained by maintaining the preservative salts solution at a temperature between about 40° F. and about 70° F.
Inventors
- 👤 Craig R. McIntyre
- 👤 Daniel A. Eakin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 07:54
CPC Classifications
B; B27; B27K; B27K3/00; B27K3/02; B27K3/08; B27K3/16; B27K3/22; B27K3/26; B27K3/28; B27K3/32; B27K5/00; B27K5/001
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
166 words
A wood pressure impregnation method comprising: (a) placing wood in a treating vessel and subjecting the wood to a vacuum 1/2 of 25 in. Hg to a pressure above atmospheric of up to 100 psig for a period up to 2 hours (b) filling the vessel with a water-borne preservative salts treating solution that reacts at elevated temperatures with wood constituents to form difficulty soluble precipitates, said treating solution having a temperature of between about 40° F. and about 70° F. while maintaining the pressure of (a), (c) adjusting the full treating vessel to a positive pressure of between atmospheric and 200 psig, and holding this pressure until a predetermined amount of treating solution has been injected into the wood, (d) releasing the pressure and returning the treating solution to a storage vessel, whereby the precipitation of preservative salts is obviated or reduced, (e) removing the excess solution from the wood at a pressure of from atmospheric to 26 in Hg, and (f) recovering the wood.
Claim 2
Dependent Claim
166 words
A wood pressure impregnation method comprising: (a) placing wood in a treating vessel and subjecting the wood to a vacuum 1/2 of 25 in. Hg to a pressure above atmospheric of up to 100 psig for a period up to 2 hours (b) filling the vessel with a water-borne preservative salts treating solution that reacts at elevated temperatures with wood constituents to form difficulty soluble precipitates, said treating solution having a temperature of between about 40° F. and about 70° F. while maintaining the pressure of (a), (c) adjusting the full treating vessel to a positive pressure of between atmospheric and 200 psig, and holding this pressure until a predetermined amount of treating solution has been injected into the wood, (d) releasing the pressure and returning the treating solution to a storage vessel, whereby the precipitation of preservative salts is obviated or reduced, (e) removing the excess solution from the wood at a pressure of from atmospheric to 26 in Hg, and (f) recovering the wood.
Claim 3
Dependent Claim
26 words
The method of claim 1 wherein a preliminary vacuum is used of between 1/4 and 1/2 of 25 in. Hg as used in a full-cell process.
Claim 4
Dependent Claim
16 words
The method of claim 1 wherein the initial air pressure used is only atmospheric air pressure.
Claim 5
Dependent Claim
40 words
The method of claim 1 wherein air is initially applied to the treating cylinder at a pressure sufficient to keep the treating solution weight pickup down to a level of from 8 to 10 lbs. per cubic foot of wood.
Claim 6
Dependent Claim
16 words
The method of claim 1 wherein the temperature is maintained between 40° F. and 70° F.
Claim 7
Dependent Claim
16 words
The method of claim 1 wherein the temperature is maintained between 45° F. and 65° F.
Claim 8
Dependent Claim
16 words
The method of claim 1 wherein the temperature is maintained between 55° F. and 60° F.
Claim 9
Dependent Claim
11 words
The method of claim 1 wherein the water-borne salts contain chromium.
Claim 10
Dependent Claim
13 words
The method of claim 1 wherein the water-borne preservative is a CCA solution.
Claim 11
Dependent Claim
52 words
The method of claim 1 wherein the major portions of the empty-cell cycle include: initial air pressure of atmospheric to 100 psig for up to 120 min., a positive pressure period of atmospheric to 200 psig for 1/2-24 hr. and a final pressure of atmospheric to 26 in. Hg for 1/4-4 hr.
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) | 1987-08-21 | 1988-02-20 | 1988-08-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-08-21 | 1992-02-20 | 1992-08-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-08-21 | 1996-02-20 | 1996-08-21 | $7700.00 | Window Closed / Lapsed |