JPH01320103A - Method of molding separated woody cellulose material and product obtained through said method - Google Patents

Abstract

PURPOSE: To enable manufacture of a rigid product by molding by removing water-soluble components in a mixture in a separated state and by substituting other alternative crosslinkable polymerizable components therefor, in a woody cellulose material separated by an explosive or rapidly released pressure. CONSTITUTION: A woody cellulose material discharged into the atmosphere instantaneously and explosively from a pressure vessel and separated is put in a column. Water as a solvent is added thereto and the solvent is made to permeate by the force of gravity, separated then and taken out. Subsequently, a water based solution of a lignin crosslinked polymer component is put in the column for humidity-permeation mixing. Then, the content of the column is taken out and dehydrated and further drying is conducted till the water content becomes about 5%, prior to molding. When the water content is once reduced in this way, the separated woody cellulose material is filled or injected in a mold with a vent. In order to produce general-purpose products thereafter, a molding temperature in the range of about 70-260 deg.C is applied and also a molding pressure in the range of about 20-700 psi is used in accordance with a desired density of molded products. The products are molded excellently in a retention time in the range of about 5 seconds to 30 minutes.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to the use of dissociated wood fiber materials.
sic material) and the products obtained by this method.

The present invention further describes isolated wood-based resins as binders that can replace, in whole or in part, phenolic resins commonly used in the manufacture of plywood, waferboard, grain-oriented fiberboard, particleboard and other molded products. It also relates to the uses of fiber materials.

The separated wood fiber material, which is the starting material for the molding method of the present invention, is
depressurization). The rapid depressurization process processes wood fiber materials including plant growth materials such as oat husks, corn stalks, bagasse, wheat straw, oat straw, barley straw, rice straw and many wood species. use. The rapid depressurization process includes the following steps: (1) Filling the separated, exposed, wet wood fiber material into a pressure vessel with a valved outlet mechanism; (2) With the valve closed, rapidly fill the pressure vessel with steam at least 400 ps i and bring substantially all of the wood fiber material to a temperature of 185-240°C within 60 seconds to remove the wood fiber material; The material is thermally softened into a plastic state; (3)
Once the plastic state is obtained, immediately open the valved outlet mechanism to instantly and explosively
and explosively discharging the wood fiber material from the pressure vessel into the atmosphere. This explosive process breaks the chemical cross-links between lignin and hemicellulose, creating a mixture of chemicals. This mixture, referred to herein as "separated wood fiber material," is a potting oil-like granule. It consists primarily of cellulose, lignin, acetic acid, glucuronic acid, furfural, xylose sugar, and xylan, each of which is substantially chemically separated from each other. Such explosion processes using steam are described in detail in our Canadian Patent Sections 1,096,374, 1,141,376 and 1.217.765, and Apparatus for use in the method is also disclosed.

In the past, it was believed that isolated wood fiber materials could be useful as animal feed or as a raw material for the manufacture of mixtures containing multiple chemical components. However, by heating and pressurizing the mixture obtained by the rapid depressurization process in a mold, the separated components in the mixture can be recombined and a highly cross-linked polymerized matrix can be obtained. discovered. molding pressure and temperature,
By varying the residence times in the mold, the degree of cross-linking of the material can be varied, thereby controlling the strength and density of the final product.

In some embodiments of the invention, the water-soluble component in the separated mixture is removed and replaced by another alternative cross-linked polymerizable component.

It has also been found that molded products can be made from mixtures of separated wood fiber materials and various fibrous or wood materials. In this case, the separated wood fiber material acts as filler and binder. Additionally, the separated wood fiber material, which acts as a binder, can encase a number of aggregates such as coal, asphalt, fiberglass, and other non-wood materials.

The invention therefore also relates to a method for forming separated wood fiber materials to produce rigid products, with or without the addition of aggregate materials. If necessary, the moisture content of the starting material can be reduced to a level suitable for molding. The feed is then filled into molds that have been previously heated to an appropriate temperature. Then,
Sufficient pressure is applied for a sufficient period of time to form a rigid product. The molded article is placed in an unheated mold under pressure and cured, if necessary, to relieve internal stresses.

The economics in the production of molded boards and other products are greatly improved by the removal of water-soluble components of the separated wood fiber material and the separation of the isolated chemicals. In other words, the cost of the crosslinking polymerization chemicals used for substitution is
This is because the value is significantly lower than that of water-soluble components. A more preferred method for extracting water-soluble compounds from the separated wood fiber material consists of the following steps: placing the separated wood fiber material into a column having openings at the top and bottom; Water is added as a solvent and gravity permeates the solvent from top to bottom through the material without stirring the contents in the column, and then the solvent is separated from the material through the lower opening of the column. Take it out. Then,
For mixing by wet osmosis, an aqueous solution of the lignin crosslinking polymerization component is added to the column, similar to the water wash described above. The column contents are then removed, dehydrated, and
Further, if necessary, it is dried to reduce the moisture content. The product is then processed in a manner similar to that described for the untreated separated wood fiber material above.
molded.

Examples of the above method and Canadian patent Canadian Patent No. 1.096,
No. 374, No. 1,141.376 and No. 1,217
, 765, the separated wood fiber material usually contains an excess amount of moisture, i.e.
Contains moisture to the extent that it interferes with the molding process. It has been found that good results can be obtained by drying to a moisture content of approximately 5% prior to molding. This drying can be accomplished by exposing the material to the atmosphere at room temperature for a sufficient period of time. Accurate control of moisture content is not essential for molding.

This is because molding can be carried out even if the water content is somewhat excessive or insufficient, although the results may be slightly inferior.

Once the moisture content is thus reduced, the separated wood fiber material is filled or injected into a mold of the desired size and shape. Molded products include particle board, wafer board, fiber hoard, hard board,
It turns out that it can be a good substitute for things like plywood.

Therefore, the shape of the mold depends on the type of product.
determined.

Molding pressure, temperature and residence time are selected depending on the type of product.

Molding can be carried out over a wide temperature range. The higher the temperature, the faster the crosslinking polymerization reaction that occurs during molding proceeds. It has been found that as the molding temperature increases, the density of the product at constant pressure increases. - Temperatures in the range of about 70 to 260°C have been found to be useful in manufacturing products for fishing purposes. By heating the mold,
It is also possible to obtain a desired molding temperature. As used herein, "molding temperature" means the temperature of the mold. Whether the entire material in the mold is heated to this temperature depends on the mold thickness and residence time. Alternatively, when molding large volume products, e.g. railway sleepers or structural parts, the starting material may be prepared in advance rather than or in addition to heating the starting material in the mold. Heating is also possible. Preheating of the material should be done in a closed container to prevent volatilization of furfural etc.

The molding pressure can also be selected from a wide range depending on the desired density of the molded product. It has been found that molding pressures in the range of about 20-1500 psi can be employed. 600-700 psi for good general purpose product production
A range of pressures may be used.

For the molded product to resemble cork, approximately 70 to 11
Molding temperatures of 0° C. and molding pressures of about 20-90 psi can be employed. Such products are biodegradable plant cultivation pots (bio-dcgradable pla pots).
It can be used to package slow-release fertilizers in tinging pots.

By performing molding at a relatively low temperature (e.g. 70-120°C) and then briefly applying a mold platen heated to about 300°C, a low-density molded product with high toughness and water resistance can be obtained. . This operation turns the cellulose on the surface of the molded product into plastic.

A molding temperature of about 120-145° C. and a molding pressure of about 100-700 psi may be used to produce a molded product having a density similar to furniture board (medium density).

To produce high-density molded products, approximately 120 to 165
A molding temperature of 0.degree. C. and a molding pressure of about 700-1500 psi may be used. By employing suitable high temperatures and pressures, a very dense product can be obtained which can replace, for example, slate for the top of a dowel table. These products have a very high density, so even a 220 diameter rifle bullet fired from close range will hit more than 4 to 5 a+m.
Don't invade.

The residence time in the mold can vary within a very wide range, depending on the thickness of the board and the desired density of the product. The material acts as an insulator. Larger thickness molded products require more time for the heat from the mold to fully penetrate the material and cure it after cross-linking occurs. To produce uniform crosslinking polymerization throughout the thickness of the product, the residence time can be increased and the temperature correspondingly decreased. It has been found that increasing residence time increases product density when temperature, pressure and thickness are constant.

Residence times ranging from about 5 seconds to 30 minutes have given good results.

The mold should be provided with vents to allow continuous dissipation of steam and other gases generated during molding.

In some cases, the molded part should be cured after molding to allow internal stress relief.

For high density products, longer curing times are required and it is preferred to transfer the as-formed molded product to an unheated mold under pressure equal to or similar to the molding pressure to cure the product.

When the separated wood fiber material is shaped as described above, the lignin crosslinks and polymerizes with furfural, fatty acids, and xylan. When the molding temperature increases to about 240°C, the acids in the separated wood fiber material react with xylan and xylose sugar at a high rate, increasing the concentration of furfural, and this high concentration of furfural causes crosslinking with lignin. Increasing the degree of polymerization creates a denser, stronger product. By controlling these reactions, the strength, water resistance, and density of the molded product can be varied.

If it is desired to increase the reaction rate and/or lower the forming temperature, an acid catalyst (such as a mineral acid, an organic acid, a Lewis acid, or a mixture thereof) can be added. The rate and extent of hydrolysis of xylan and xylose sugars to furfural can be increased. This generated furfural increases the degree of crosslinking polymerization with lignin. Addition of paraformaldehyde, hexoses free or bound as glycosides or short-chain oligosaccharides, or other cross-linking agents to the isolated wood fiber material results in a higher degree of cross-linking than occurs with furfural alone. It is also possible to obtain the degree of polymerization. The furfural is produced from xylose and xylan in the material during the rapid depressurization process and heating cycles within the mold.

- In the method described in , the separated wood fiber material is
Consists of fillers and binders in molded products. However, the present invention uses sawdust, wood flakes,
afer), wood fibers
, straw fibers, bagasse fibers (
It also includes the use of separated wood fiber materials in combination with materials such as fiberglass, asbestos fibers, carbon fibers, coal, sand, etc. In this case, the separated wood fiber material is
In molded products, it acts primarily as a binder, although it also acts as a filler. That is, it completely or partially replaces phenolic resins and similar substances that are generally used as binders when molding materials such as the above-mentioned sawdust. When used in this manner, the molding material such as sawdust and the separated wood fiber material should be thoroughly mixed prior to molding.

Generally, the higher the proportion of molding material, the softer the molded product. For example, to produce a relatively soft final product, one part of the separated wood fiber material is mixed with about four parts of sawdust. To obtain a stiffer board, a ratio of 1 part separated wood fiber material to about 1 part sawdust or less is preferred.

It should be noted that in addition to the above, various combinations of mixtures can be used, and various combinations of molding pressure, temperature, and residence time can be used in order to obtain molded products with desired properties suitable for specific applications. It will be obvious to those skilled in the art that there may be a combination. In addition, if necessary,
It goes without saying that preservatives, water repellents, flame retardants, etc. may be added prior to molding to provide additional properties.

Furthermore, it is also possible to mix fertilizer into the material to be shaped prior to shaping. The resulting product allows for a slow release of fertilizer into the soil and prevents the rapid run-off of fertilizer and the contamination of waterways that so often occur when using conventional fertilizers.

In the embodiments described below, water-soluble substances in the separated wood fiber material are removed by washing with water. As a result of this removal operation, the crosslinking polymerization ability of the mixture is largely lost. Water-soluble substances include acetic acid, glucuronic acid, vanillin, syringaldehyde, vegetable proteins, furfural, inorganic salts,
Contains xylose and xylose oligomers.

In order to restore the bonding properties of the water-washed, separated wood fiber material, it is necessary to add a crosslinking polymeric composition.

Compositions of this type usually contain an acidic catalyst as well as a carbohydrate. Examples of acidic catalysts include one or more of various acids such as mineral acids such as sulfuric acid, organic acids such as acetic acid, and Lewis acids such as zinc chloride, and examples of hydrocarbons include separated wood cellulose. Examples include pentose, hexose, glycooxides or short chain oligosaccharides thereof, or mixtures of pentose and hexose, such as those present in water-soluble substances extracted from the material. If pentose is used, the effective crosslinking agent during molding is
When furfural is used and a hexose is used, the effective crosslinking agent during molding is hydroxymethylfurfural. Accordingly, the amorphous carbohydrate component in the composition may be replaced or supplemented with furfural or hydroxymethylfurfural. Experience has shown that hydroxymethylfurfural is by far the best cross-linking polymerizing agent, so hexoses are more preferred.

The separated wood fiber material is washed in a column to remove water-soluble substances. This operation is carried out using a column with an upper opening for adding solvent and accommodating the separated wood fiber material and a lower opening for removing the eluate (herein referred to as "eluate"). liquid"
means the solvent containing dissolved or suspended material that is removed from the column). The column is preferably in the form of a cylinder with an open top or a tube of rectangular cross-section, with a drainage system at the bottom for connection to a line and container for collecting the eluate.

The column may be filled with separated wood fiber material to an appropriate height depending on the degree of extraction required. The inventor has obtained good results with columns packed to a height of 5 feet, but has also been able to work without difficulty at heights from 1 foot to over 20 feet.

Water is naturally present in the wood fiber material and is also added by absorption during the first stage of the rapid depressurization process. The water-soluble fraction of the separated wood fiber material is therefore already dissolved by the water in the material.

Close packing or compaction of materials within the column should be avoided as this will impede solvent flow. Water is then added to the column. The added water percolates downward through the bed, pushing forward the water already present in the column containing water-soluble components. The solution coming out of the bottom of the column is initially very concentrated, but the presence of bores or channels within the packed material is not uniform, so the incoming liquid does not flow through all liquid flow channels. .

Therefore, complete plug flow is not achieved and the concentration of dissolved substances decreases exponentially. Water-extractable materials constitute approximately 25% by weight (dry basis) of the separated wood fiber material. When the separated wood fiber material was loosely packed in a 5 foot column, more than 99% of the water soluble material was removed using only about twice the column volume of water.

Removal of water-soluble substances can be carried out using conventional pulp manufacturing techniques, e.g.
Other methods can also be used, such as using very large amounts of water to perform the solvent exchange by highly diluting the already existing solution.

From the point of view of using the water-washed material for molding, it does not matter how the water-soluble components are removed. However, the column method described above is preferred as it allows economical recovery of water-soluble components.

The separated wood fiber material after washing with water is substantially free of chemical components capable of crosslinking polymerization with lignin.

If necessary, it is also possible to wash the separated wood fiber material more slowly with water so that only a portion of the compound capable of crosslinking polymerization is removed.

In order to restore the binder properties of the material, it is necessary to add a suitable crosslinking polymeric composition. A typical composition is a combination of a water-soluble acid (sulfuric acid, acetic acid, etc.) and a pentose or hexose (or a mixture of both). The pentose and hexose may be in a free form, a glycoside form, or a complex such as a low-molecular weight oligosaccharide. These carbohydrates may be obtained from the separated wood fiber material by washing with water. A crosslinking polymerization agent composition, which can contain an acid in a concentration of 0.2 to 1.0% and a sugar in a range of 2 to 12%, is added from the top of the column and passed downward through the material in the column. Moving. Initially, water from the previous process comes out in a plug flow state. Add enough of the indicated composition to ensure that the pH of the aqueous eluate from the column is as low as the solution from the inlet, so that the acid leaving the column equally wets the contents throughout the column. Make sure to show that.

At this point, the material is removed from the column, dehydrated as much as practical, and further dried in air or in a heated dryer. The material is then ground or crushed to a fine powder suitable for use as a binder. Prior to molding, the dry material is mixed with fibrous aggregate materials, preservatives, water resistance agents, flame retardants, etc., depending on product specifications.

To improve the water resistance of molded parts when using water-absorbing fillers (sawdust, wood chips, etc.), use sawdust, wood chips, etc.
Wood chips or the like may be impregnated with an acid/carbohydrate crosslinking polymerization agent. In this case, furfural or hydroxymethylfurfural is generated at the binder/filler interface to form a seal around the filler. Generally, the material can be shaped in a manner similar to separated wood fiber material that has not been subjected to a water washing process.

In some cases it may be necessary to subject the molded article to combustion and it is preferred to include aggregates such as coal in the product. In such cases, the cross-linking polymerization agent can be mixed with a combustion promoter (such as a nitrate), a flame colorant (various inorganic salts depending on the desired color), etc. before loading into the column. Such shaped fuels can be in the form of fireplace wood, briquette-like masses, and the like.

Neither mineral acid nor organic acid is contained in the crosslinking polymerization agent composition,
If a Lewis salt is present, this salt should be present as a mineral in the dry state, ideally with a water content of less than 1%.
It is necessary to be mixed.

As long as the acid acts as a catalyst, a small amount may be used, but the absolutely necessary amount is determined by the properties of the fibrous material or aggregate material, the ability to draw out the acid from the crosslinked polymeric carbohydrate by capillary action, etc. In the total separated wood fiber material, the amorphous carbohydrate content is in the range 15-25%, depending on the original wood fiber material. By washing the separated wood fiber material with water and combining it with other cross-linking polymerizable carbohydrate agents, this sugar content can be reduced by more than half, yet the final composition still contains an effective binder. Work as.

(that's all)

Claims (1)

[Claims] [1] A method for forming a separated wood fiber material comprising the following steps: (A) Producing a separated wood fiber material by the following steps; (1) Segmenting and wetting (2) with the valve closed, rapidly filling the pressure vessel with steam at at least 400 psi to remove substantially all of the wood fiber material in a state of Bring the fiber material to a temperature of 185-240°C within 60 seconds to thermally soften the wood fiber material into a plastic state; (3) Once the plastic state is obtained, immediately open the outlet mechanism with a valve. By opening and ejecting the wood fiber material from the pressure vessel into the atmosphere in an instantaneous and explosive manner, the cross-links between the lignin and hemicellulose of the wood fiber material are destroyed and the mixture of water-soluble chemicals is released. Let it form,
forming a separated wood fiber material; (B) washing the separated wood fiber material with water to substantially remove the water-soluble chemical; (C) forming the separated wood fiber material with water; A step of preparing a separated wood fiber material that can be molded by adding a crosslinking polymerization agent and a catalyst to a wood fiber material obtained by adding a crosslinking polymerization agent to a wood fiber material. and complexes, furfural, hydroxyfurfural and mixtures thereof;
the catalyst is an acidic catalyst; (D) drying the moldable separated wood fiber material to a moisture content of about 5% or less; (E) the moldable separated wood fiber material (F) Filling the moldable separated wood fiber material in the mold at a temperature in the range of 70 to 260°C for 5 seconds to 30 minutes. applying a pressure of 20 to 700 psi for a time in the range of minutes to form a rigid article; and (G) removing the formed article from the mold. [2] The method according to claim 1, wherein the mold is preheated to a temperature in the range of about 70 to 260°C, and a mold platen preheated to about 300°C is applied to the molded product after molding. . [3] Preheating the mold to about 70-110°C and applying a pressure of about 20-90 psi to the material in the mold when a molded product having a density similar to that of cardboard is required. The method described in Section 1. [4] Preheating the mold to about 120-145°C and applying a pressure of about 100-700 psi to the material in the mold when a molded product having a density comparable to furniture board is required. The method described in Section 1. [5] The method according to claim 1, wherein a preservative component is added to the separated wood fiber material prior to molding. [6] The method according to claim 1, wherein a water repellent component is added to the separated wood fiber material prior to molding. [7] The method according to claim 1, wherein a flame retardant component is added to the separated wood fiber material prior to molding. [8] The method according to claim 1, wherein the acidic catalyst is selected from the group consisting of mineral acids, organic acids, and Lewis acids. [9] The method according to claim 1, wherein the molded product is transferred from a hot mold to a non-heated mold under equal pressure to cure the molded product. [10] Separated wood fiber material and at least one type selected from the group consisting of wood wafer, wood fiber, straw fiber, bagasse fiber, sawdust, glass fiber, asbestos fiber, carbon fiber, fertilizer, coal, and sand. 2. The method of claim 1, further comprising the step of mixing with a filler material. 11. The method of claim 10, wherein the separated wood fiber material contains excess moisture and the moisture content is reduced to about 5% or less prior to shaping. [12] The method according to claim 10 or 11, wherein the filler material is sawdust and is used in a ratio of 4 parts or less to 1 part of the separated wood fiber material. [13] The method of claim 10 or 11, wherein the mold is preheated to a temperature between about 70 and 260°C. [14] The method according to claim 13, wherein a mold platen preheated to about 300° C. is applied to the molded product. [15] The method according to claim 10 or 11, wherein a preservative component is added to the material to be molded prior to molding. [16] The method according to claim 10 or 11, wherein a water repellent component is added to the material to be molded prior to molding. [17] Claim 10 or 11, in which a flame retardant component is added to the material to be molded prior to molding.
The method described in section. [18] The method according to claim 10 or 11, wherein the molded product is transferred from a hot mold to a non-heated mold under equal pressure to cure the molded product. [19] The method according to claim 1, wherein the crosslinking polymerization agent is selected from the group consisting of free or bound pentose and hexose. [20] The method according to claim 1, wherein the crosslinking polymerization agent is furfural. [21] The method according to claim 1, wherein the crosslinking polymerization agent is hydroxyfurfural. [22] The concentration of acidic catalyst in the crosslinking polymerization agent is about 0.2 to 1
．． 2. The method of claim 1, wherein the concentration of crosslinking polymerization agent in the crosslinking polymerization agent/catalyst is within the range of about 2-12%. [23] The method according to claim 10 or 11, wherein a crosslinking polymerization agent and a catalyst are impregnated into the filler material prior to molding. [24] A molded product manufactured by the method according to claim 1. [25] A molded product manufactured by the method according to claim 10.