JPS6030309A - Manufacture of composite product from lignocellulose material - Google Patents

Abstract

PURPOSE:To produce a composite product without adding adhesive bonding agent by a method in which finely crushed raw material composed of lignocellulose material containing sugar is formed into a desired mat after it has been dried, and then it is formed under heating and pressurizing. CONSTITUTION:The raw material composed of the lignocellulose material containing sugar (e.g. the bagasse of sugar cane, cone cane and sunflower cane, etc.) is finely crushed, and is divided into particle, fiber, strand and flake. After this finely crushed material has been dried, it is formed into a desired mat. This mat is press-heated under sufficient pressure and in sufficient time to compress the formed product at the temperature equal to or higher than 180 deg.C. The kinds of liberated sugar and saccharid are chemically sophisticated under pressurizing and heating and act as adhering and reinforcing agent. The formed product excellent in strength, dimensional stability and resistance for boiled water and aid hydrolyzing may be obtained without adding other adhesive bonding agent or adhesive.

Description

DETAILED DESCRIPTION OF THE INVENTION Corn stalks, sunflower stalks, flax stalks and other lignocellulosic materials, especially those of non-arboreal plants containing water-soluble and easily extractable sugars, carbohydrates or saccharides. Relating to manufacturing composite products from.

More particularly, the present invention provides for the production of sugar-containing lignocellulosic materials such as sugarcane bagasse, sorghum stalks, corn stalks, sunflower stalks, flax stalks, etc., without the addition of adhesive binders or adhesives. Concerning manufacturing composite products. This production is accomplished by using free sugars, carbohydrates or saccharides as an adhesive and voice enhancer with the addition of heat.

In the conventional manufacture of sugarcane bagasse panel products, synthetic thermosetting resin binders such as phenol-formaldehyde and urea-formaldehyde are conventionally used, in which case the more expensive phenol binders are used for exterior grade products. -Formaldehyde is used. A large portion of the total material cost of a composite product is due to conventional resin binders. It is economically attractive to produce composite products without the use of expensive resin binders. Furthermore, the binderless manufacturing system simplifies the manufacturing process and reduces manufacturing costs by eliminating mixing operations and equipment. Therefore,
It will be readily appreciated from an economic and technical point of view that it is desirable to use binderless methods in the manufacture of composite products.

In the conventional manufacturing process of bagasse panel products, removal of pith and residual free sugars is essential for a good quality panel product. This pith is a very short, thin-walled cell compared to true fibers, and although it contains a higher proportion of sugars, it does not contribute to the strength of the final product.

Since the pulp is fluffy, especially when using liquid resin,
It will absorb excess resin binder.

The pith also acts like a sponge and, if not removed from the bagasse composite panel product, will wick water and swell excessively. Bagasse also typically contains between 0 and 6% residual sugar, depending on the type of stalk, its maturity, the harvesting method and the efficiency of the fine grinding equipment. Residual sugars in bagasse, if not removed or minimized prior to processing, can cause problems during board manufacture and subsequent use. Sugars are not chemically compatible with conventional resin binders used in bagasse board production and can interfere with bonding and result in poor strength. Unless the residual sugars are chemically modified or consumed during hot pressing, the sugars will begin to ferment when the bagasse board is exposed to humid conditions, thus emitting unpleasant odors and eventually becoming chemically and biological deterioration. This would substantially shorten the useful life of the bagasse pods in use.

Therefore, sharpening and desugarization operations are necessary if one hopes to produce a satisfactory product from sugarcane bagasse. These operations not only increase manufacturing costs, but also
Make the process complicated.

In marked contrast to the conventional methods described above, it has been found that composite bagasse products such as building boards, furniture boards, reconstitution materials and molded articles can be produced without the use of resin binders and without the removal of pith and residual sugars. . Sugars, carbohydrates or saccharides provide not only a binder but also a reinforcing element in the lignocellulosic material, resulting in a composite product with good strength properties and excellent dimensional stability.

According to the invention, the method essentially requires a finely ground mass of bagasse or other lignocellulosic material containing a high proportion of free sugars, especially from non-arboreal plants.

This finely ground material is first dried to a low moisture content, preferably 1 to r% based on oven dry weight. This material may be made entirely of, or partially combined with, other lignocellulosic or non-lignocellulosic materials. This material is bonded and thermally cured in situ without the addition of a resin binder at a temperature of at least 110°C and at a pressure sufficient to form a molded article with the above materials. Shape for a sufficient period of time to
The residual sugar is converted into an insoluble and infusible polymeric substance that is extremely resistant to boiling water and acid hydrolysis.

Micronization of the raw material is particularly useful because the individual particles, flakes or strands facilitate and improve forming and shaping operations. Moreover, milling simultaneously reduces the presence of cuticle material from the plant stem to a minimum amount. Normally, the thin outer layer of the epidermis, consisting of epithelial material, is impervious to water and adhesion. In binder-free systems,
There is uniform and close compression between individual particles, strong bonding,
Finer particles usually yield better products, primarily because they produce a denser and smoother texture.

On the contrary, conventional methods do not economically allow the use of finer particles. This is because the finer the particles,
This is because it is necessary to increase the amount of the expensive synthetic resin binder.

In the present invention, it is preferred to use very fine particles when combined with other sugar-free lignocellulosic materials to produce composite products. In effect, the fine particles act like powdered resin binders in conventional manufacturing methods.

The beneficial effects of the use of sugarcane bagasse and other sugar-containing lignocellulosic materials, especially of non-woody plants, are
This may be attributed to the sugars that melt during thermoforming and polymerize and bind the lignocellulosic material in situ and the water-soluble substances formed in the material.

Furthermore, the sugars and water-soluble substances that have permeated through the cell walls of the lignocellulosic tissue will also be denatured and thermally hardened to become a cross-linked hard substance, which will serve as a filler throughout the entire molded article.

The molded articles thus exhibit excellent strength properties, dimensional stability and resistance to boiling water and acid hydrolysis. These results are best obtained when the lignocellulosic material contains a high proportion of sugars and water-soluble substances.

The chemical reactions involved in the bonding system of the present invention are not fully understood. It is well known that sugars are degraded by both acids and alkalis to small molecular weight compounds, with water being lost from the sugar molecules. Approximately 20% of hydroxymethyl-furfural is produced when weak acids or even pure water under pressure at temperatures of 130-170° C. are reacted with sugars. Other intermediates and furfural derivatives could be produced from carbohydrates under similar conditions. These derivatives are highly reactive and resist further polymerization and modification to form insoluble to infusible crosslinked materials at elevated temperatures.

It is believed that all or some of the reactions described above may be included in the bond production methods of the present invention. Furthermore, it is believed that the chemical alteration of sugars and water-soluble substances at elevated temperatures is an irreversible chemical and physical change and is essential to the present invention. It is presumed that this product contains a furan dehydration product of a carbohydrate consisting of dimethyl-furfural.

The physical and mechanical properties of the sugarcane bagasse produced according to the invention are at least comparable to or better than those of conventional bagasse pods produced by the conventional use of expensive synthetic resin binders. It was discovered that

Embodiments of the invention will be described and illustrated in detail in the Examples below.

Example 1 Dried sugarcane bagasse with a moisture content of 3.1% was obtained from a conventional fine grinding mill. This stuff is 7.2% by weight
It contains 4 (,7) water-soluble substances.
% reducing sugars (as glucose) were found. Further experiments have shown that bagasse contains approximately 70% by weight of true fibers and 3.
It was found to contain 0% by weight of pith.

Grinding the bagasse in a hammer mill produced two fractions of particles. The particles that passed through the /Otsu mesh Tyler sieve were used for the surface layer, and the particles larger than /6 mesh were used as the core material for the 3-layer mat. The face center ratio by oven dry weight was /:l. From this mat! OOx!
;OO × / Ha / Hot compress the fighting board for is minutes 2
a temperature of 35°C and 2. Specific gravity at a pressure of 0.0 MPa.
It's 72 things. During this hot compression, amounts of substances other than water were observed to evaporate as water vapor and various fumes. The weight loss of the mat reaches r,<z%;
The water content was much higher than the 30g% of the original mat.

This extra weight loss indicates that there was a severe chemical reaction at elevated temperatures. According to final analysis, only 0.7%
It was confirmed that reducing sugars remained in the finished board. This amount was much lower than the amount in commercial bagasse boards.

According to the bending strength test, the dry MOR (modulus of rupture) is /lJ
MPa, dry MOE (modulus of elasticity) is 3. It was IGPa. The wet MOR was A MPa. Wet flexural strength was obtained by immersing the specimens in boiling water for 2 hours and then testing them wet and cold.

Example 2 Sugarcane hulls were made using a sugarcane separator that separates the internal sugar-containing soft pulp from the external hard layer or skin of the sugarcane stalk. 2g of peeled bagasse since no sugar was extracted from it. It contained 6% water-soluble substances and 7763% reducing sugars.

This peeled bagasse is shredded to a width and thickness of 8! or 3,
A strand containing approximately 5% moisture was produced. The strands have lengths ranging from /, t to 3QQmtn, are unidirectionally oriented, and shaped to form
It was made into a composite material with dimensions of RTSO and specific gravity of O, tS. Molding temperature: 30 minutes; 3. 22 at a pressure of lIMPa
! ;℃. According to the bending strength test, the dry MOR is 31. AMPa and wet MOR were 6 MPa.

Example 3 Fresh sugarcane husks made using a sugarcane separator were subjected to a treatment of boiling in water for different times to remove sugar. Three batches of peel each! , IO and boiled for 30 minutes; a second batch was not boiled and was included in the experiment as a control. After boiling, the skin was dried to a moisture content of g%, then ground in a hammer mill and passed through a ±20 mesh Tyler sieve. Chemical analysis showed that residual sugar was inversely proportional to increasing boiling time. This also indicates a nearly linear relationship between water-soluble substances and reducing sugars. Table 1 below shows the results of the boiling treatment.

Table 1 Content of one piece of skin treated by boiling in water as oven-dry weight ), two different press times (IO and 2
0 minutes) and clamping pressure 3. using tIMPa, 3;00
x! ; Specific gravity is approximately 0.7 at 00 X //, /fnm
I made 6 boards of 0. The water content of the face layer composition (-20 mesh) is about 9.0%, and the water content of the core composition (+,
! O mesh) was 3.0%. The face center ratio of the mat based on oven dry weight was /:/. The test results for t boards are shown in Table 2 below.

As is clear from the test results shown in Table 2, the properties of the board improve as the sugar content of the skin increases. Also, the higher the pressing temperature and the longer the pressing time, the better the quality of the board. skin composition board
Mainly due to extremely fine particles, it had a dense and smooth surface and dark brown color, and had a high sugar and water content in the matte phase. The dimensional stability of the skin bagasse pods, especially the boards made with higher sugar content and harsher pressing, was superior to that of conventional products. This is due to the binding and liter-enhancing effect of polymerized sugar.

Example 4 This example demonstrates the production of a mixed composite product from sugarcane bagasse in combination with other lignocellulosic materials.

When sugarcane peel bagasse containing about 79% reducing sugar was ground in a no-mer mill, it passed through a 1.20 mesh Tyler sieve. The peeled bagasse pieces were mixed with poplar tree pieces of similar size in a weight ratio of 70:30. A mat was made from this mixture and hot-pressed at 235°C and a pressure of 2.1 MPa for 70 minutes to give a specific gravity of 0.72! ;00
I made a board of x300×///mm. According to the static bending test, the dry MOR is /,! ',jMP&,wet MO
R was /MPa. Initial binding test is 390
A tensile vertical strength of kPa was given.

Example 5 This example shows that similar results can be obtained using other sugar-containing lignocellulosic materials.

Sorghum stalks containing about 1/2% reducing sugars were dried to a moisture content of 3% and ground in a hammer mill to pass through a 20 mesh Tyler sieve. This composition was used to prepare boards (!; 00x!; 00x //, /
RNM specific gravity 0.7! ; )made. According to the test results, the dry MOR is /1.5 MPa.

Wet MORil, 9. ,! MPa, the initial bond strength was +lrOkPa.

Corn stalks containing about 1/2% soluble material or about 7% reducing sugars were dried to a moisture content of 3% and ground in a hammer mill to pass through a 20 mesh Tyler sieve. This composition was used to form board (!; O
Ox! ; Specific gravity O, Ir2 at 00 x //, /am
)made. According to the test results, the dry MOR is /11.
3MPa, wet MOR is 7. IIMPa.

The initial bond strength was 320 kPa.

Patent applicant: Dai 1) Shoji

Claims (10)

[Claims] (1) Raw material consisting of sugar-containing lignocellulose material,
Separating into particles, fibers, strands and flakes, drying the finely pulverized raw material, forming the pre-dried raw material into a desired mat, and compressing the formed mat into a molded article at a temperature of 110° C. or higher. Press and heat under sufficient pressure and time to make the adhesive bond develop and heat cure in situ, forming an insoluble and infusible bond with sugar and water soluble as a binding and thickening agent. Modifies and polymerizes into a crosslinked substance,
A method for producing composite products from finely divided sugar-containing lignocellulosic materials without the addition of adhesive binders, comprising the steps of: (2) A patent in which the sugar-containing lignocellulosic material is sugarcane bagasse, sorghum stalks, corn stalks, sunflower stalks, flax stalks, and other non-woody plants containing sugars and water-soluble substances. The method according to claim (1). (3) the above sugar is water-soluble and easy to extract;
and is a free sugar, carbohydrate, or saccharide that is easily denatured and can be thermally cured by applying heat to become an insoluble and infusible substance that can be combined and increased in volume. ) method. (4) The method of claim (1), wherein the sugars and water-soluble substances formed in the lignocellulosic material of item (h) are crosslinked polymeric substances that are resistant to temperature elevations of 110° C. or higher. (5) The method according to claim (1), wherein the thermoforming and pressing temperature is 2.20°C or higher. (6) The above-mentioned sugars and water-soluble substances remaining in the finished composite product are significantly reduced by chemical modification and weight loss during the molding operation at elevated temperatures above Izo°C. 1) Method. (7) Finely pulverizing the sugar-containing lignocellulose material,
Claim (1) characterized by a composite product, together with other lignocellulosic or non-lignocellulosic materials.
Section method. (8) Claim No. 1, wherein the sugar, water-soluble substance and pith are partially removed or not removed before manufacturing.
Section method. (9) pulverizing the sugar-containing lignocellulosic material into extremely fine particles or fibers for the production of composite products with strong binding strength, good dimensional stability and dense, uniform, smooth, fine texture; The method according to claim (1). (10) The above composite product is a building board, a furniture board,
The method of claim 1, wherein the reconstitution lumber is a compressed refractory log and a molded article with a waterproof bond that is resistant to boiling water and acid hydrolysis.