US3900334A
Expired / Lapsed
US
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Lignocellulosic molding method and product
Assignee: University of California Berkeley
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Filing: 1973-09-27
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Granted: 1975-08-19
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Expires: 1993-09-27
Abstract
Abstract Particulate lignocellulosic materials containing water are subjected to oxidation with nitric acid, oxygen or with a mixture of oxygen and nitric acid under conditions adapted to form carboxylic groups, along with some carbonyl groups. As a result of this treatment the oxidized material becomes activated so as to undergo self-bonding when it is later molded under elevated conditions of temperature and pressure. This oxidation reaction proceeds at elevated temperatures until there has been a net consumption by the lignocellulose of about 1.25 to 25 weight percent of oxygen as supplied either as such and/or by way of nitric acid. These percentages are calculated on a dry lignocellulosic material basis. The oxidized product can then be pressed into the desired shape under elevated pressures and temperatures effective to induce esterification or other molecular cross-linking reactions between functional groups present in the lignocellulosic molecule or between such groups and those of other chemicals which are added, thus providing a molded structure. Board-shaped as well as other molded products of high strength and excellent resistance to moisture absorption can thus be obtained from a variety of lignocellulosic raw materials.
Inventors
- 👤 David L Brink
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 22:06
CPC Classifications
C; C08; C08H; C08H8/00; C08K; C08K5/00; C08K5/04; C08K5/09; C08K5/16; C08K5/17
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
150 words
A METHOD OF PREPARING AN OXIDIZED, PARTICULATE, LIGNOCELLULOSIC PRODUCT WHICH CAN BE MOLDED BETTWEEN PLATES IN A PRESS AT ELEVATED TEMPERATURES ABOVE ABOUT 100*C AND ELEVATED PRESSURES ABOUT 100 PSIG INTO A SHAPED ARTICLE HAVING GOOD STRENGTH AND DIMENSIONAL STABILITY, WHICH COMPRISES OXIDIZING THE PARTICULATE, LIGNOCELLULOSIC MATERIAL AT AN ELEVATED TEMPERATURE ABOVE ABOUT 0*C WITH AT LEAST ONE OF NITRIC ACID AND OXYGEN GAS IN AN AMOUNT AND UNDER CONDITIONS WHEREBY SAID LIGNOCELLULOSIC MATERIAL CONSUMES FROM ABOUT 1.25 TO 25 WEIGHT PERCENT OF OXYGEN, BASED ON THE DRY WEIGHT OF THE PARTICULATE LIGNOCELLULOSIC MATERIAL, AND TERMINATING SUCH OXIDATION AFTER EVOLUTION OF GAS HAS SUBSTANTIALLY CEASED FOLLOWED BY MOLDING THE OXIDIZED LIGNOCELLULOSIC MATERIAL BETWEEN PLATES IN A PRESS UNDER SAID ELEVATED PRESSURE AND TEMPERATURE ABOVE 100*C TO EFFECT CROSS-LINKING WITHIN THE MATERIALS AND DENSIFY THE SAME AND TO REDUCE THE MOISTURE CONTENT IN THE MOLDED PRODUCT TO BELOW ABOUT 10 PERCENT.
Claim 2
Independent Claim
150 words
A METHOD OF PREPARING AN OXIDIZED, PARTICULATE, LIGNOCELLULOSIC PRODUCT WHICH CAN BE MOLDED BETTWEEN PLATES IN A PRESS AT ELEVATED TEMPERATURES ABOVE ABOUT 100*C AND ELEVATED PRESSURES ABOUT 100 PSIG INTO A SHAPED ARTICLE HAVING GOOD STRENGTH AND DIMENSIONAL STABILITY, WHICH COMPRISES OXIDIZING THE PARTICULATE, LIGNOCELLULOSIC MATERIAL AT AN ELEVATED TEMPERATURE ABOVE ABOUT 0*C WITH AT LEAST ONE OF NITRIC ACID AND OXYGEN GAS IN AN AMOUNT AND UNDER CONDITIONS WHEREBY SAID LIGNOCELLULOSIC MATERIAL CONSUMES FROM ABOUT 1.25 TO 25 WEIGHT PERCENT OF OXYGEN, BASED ON THE DRY WEIGHT OF THE PARTICULATE LIGNOCELLULOSIC MATERIAL, AND TERMINATING SUCH OXIDATION AFTER EVOLUTION OF GAS HAS SUBSTANTIALLY CEASED FOLLOWED BY MOLDING THE OXIDIZED LIGNOCELLULOSIC MATERIAL BETWEEN PLATES IN A PRESS UNDER SAID ELEVATED PRESSURE AND TEMPERATURE ABOVE 100*C TO EFFECT CROSS-LINKING WITHIN THE MATERIALS AND DENSIFY THE SAME AND TO REDUCE THE MOISTURE CONTENT IN THE MOLDED PRODUCT TO BELOW ABOUT 10 PERCENT.
Claim 3
Dependent Claim
11 words
The moldable lignocellulosic material obtained by the method of claim 1.
Claim 4
Dependent Claim
11 words
The molded lignocellulosic product obtained by the method of claim 1.
Claim 5
Dependent Claim
58 words
The method of claim 3 wherein the oxidized lignocellulosic material is treated with from about 0.5 to 15 weight percent, based on the dry weight of said material, of a chemical non-degrading to said material and which is effective to provide molecular cross-linkages as the treated material is subjected to the step of being molded in a press.
Claim 6
Dependent Claim
11 words
The molded lignocellulosic product obtained by the method of claim 4.
Claim 7
Dependent Claim
26 words
The method of claim 4 wherein the oxidation of the particulate, lignocellulosic material is effected with nitric acid at temperatures ranging from about 0* to 100*C.
Claim 8
Dependent Claim
26 words
The method of claim 4 wherein the oxidation of the particulate, lignocellulosic material is effected by oxygen gas at temperatures ranging from about 80* to 150*C.
Claim 9
Dependent Claim
32 words
The method of claim 4 wherein the oxidation of the particulate, lignocellulosic material is effected with a mixture of nitric acid and oxygen gas at temperatures ranging from about 0* to 100*C.
Claim 10
Dependent Claim
33 words
The method of claim 8 wherein the nitric acid employed to oxidize the particulate, lignocellulosic material is formed in situ on said material by the reaction of nitric oxide with oxygen and water.
Claim 11
Independent Claim
135 words
A method of preparing an oxidized, particulate, lignocellulosic product which can be molded between plates in a press at elevated temperatures and pressures into a shaped article having good strength and dimensional stability, which comprises oxidizing the particulate lignocellulosic material with nitric acid at a temperature ranging from about 0* to 100*C. until there has been a net consumption of from about 2.5 to 30 percent nitric acid based on the oven dry weight of the lignocellulosic material, said oxidation being conducted by first treating the product at substantially ambient temperature with said nitric acid to impregnate the material with the acid and effect an initial reaction accompanied by evolution of gas, then gradually increasing the temperature to above about 75*C. to effect a final reaction, and terminating the reaction after cessation of gas evolution.
Claim 12
Independent Claim
135 words
A method of preparing an oxidized, particulate, lignocellulosic product which can be molded between plates in a press at elevated temperatures and pressures into a shaped article having good strength and dimensional stability, which comprises oxidizing the particulate lignocellulosic material with nitric acid at a temperature ranging from about 0* to 100*C. until there has been a net consumption of from about 2.5 to 30 percent nitric acid based on the oven dry weight of the lignocellulosic material, said oxidation being conducted by first treating the product at substantially ambient temperature with said nitric acid to impregnate the material with the acid and effect an initial reaction accompanied by evolution of gas, then gradually increasing the temperature to above about 75*C. to effect a final reaction, and terminating the reaction after cessation of gas evolution.
Claim 13
Dependent Claim
11 words
The moldable lignocellulosic product obtained by the method of claim 10.
Claim 14
Dependent Claim
33 words
The method of claim 10 wherein the nitric acid employed to oxidize the particulate, lignocellulosic material is formed in situ on said material by the reaction of nitric oxide with oxygen and water.
Claim 15
Independent Claim
204 words
The method of making a molded, densified lignocellulosic product having good strength and dimensional stability which comprises oxidizing particulate lignocellulosic material with an oxidizing agent comprising at least one of nitric acid and oxygen gas at a temperature above 0*C in an amount and conditions until there has been a net consumption of from about 1.25 to 25.0 weight percent of oxygen based on the oven dry weight of said lignocellulosic material, said oxidation being conducted by first treating the lignocellulosic material at substantially ambient temperature with said oxidizing agent to impregnate the material therewith and to effect an initial reaction which is accompanied by evolution of gas, gradually increasing the temperature to above about 60*C to effect final reaction by which carboxyl groups are formed on the lignocellulosic molecule, terminating the reaction after gas evolution has substanTially ceased to thus form an oxidized moldable product, molding said product between plates in a press at an elevated temperature of above about 100*C and at an elevated pressure of above about 100 psig to effect cross linking within the material being pressed and to densify the same, and maintaining said pressing to reduce the moisture content in the pressed product to below about 10 percent.
Claim 16
Independent Claim
204 words
The method of making a molded, densified lignocellulosic product having good strength and dimensional stability which comprises oxidizing particulate lignocellulosic material with an oxidizing agent comprising at least one of nitric acid and oxygen gas at a temperature above 0*C in an amount and conditions until there has been a net consumption of from about 1.25 to 25.0 weight percent of oxygen based on the oven dry weight of said lignocellulosic material, said oxidation being conducted by first treating the lignocellulosic material at substantially ambient temperature with said oxidizing agent to impregnate the material therewith and to effect an initial reaction which is accompanied by evolution of gas, gradually increasing the temperature to above about 60*C to effect final reaction by which carboxyl groups are formed on the lignocellulosic molecule, terminating the reaction after gas evolution has substanTially ceased to thus form an oxidized moldable product, molding said product between plates in a press at an elevated temperature of above about 100*C and at an elevated pressure of above about 100 psig to effect cross linking within the material being pressed and to densify the same, and maintaining said pressing to reduce the moisture content in the pressed product to below about 10 percent.
Claim 17
Dependent Claim
15 words
The method of claim 13 wherein the moisture content is reduced below about 5 percent.
Claim 18
Dependent Claim
11 words
The molded lignocellulosic product obtained by the method of claim 13.
Claim 19
Dependent Claim
58 words
The method of claim 13 wherein the oxidized lignocellulosic material is treated with from about 0.5 to 15 weight percent, based on the dry weight of said material, of a chemical non-degrading to said material and which is effective to provide molecular cross-linkages as the treated material is subjected to the step of being molded in the press.
Claim 20
Dependent Claim
11 words
The molded lignocellulosic product obtained by the method of claim 16.
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) | 1978-08-18 | 1979-02-17 | 1979-08-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-18 | 1983-02-17 | 1983-08-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-18 | 1987-02-17 | 1987-08-19 | $7700.00 | Window Closed / Lapsed |