WO2023284729A1

WO2023284729A1 - Biological formaldehyde-free adhesive, biological composite material and preparation method therefor

Info

Publication number: WO2023284729A1
Application number: PCT/CN2022/105163
Authority: WO
Inventors: 赵晓斌
Original assignee: 武秀英
Priority date: 2021-07-12
Filing date: 2022-07-12
Publication date: 2023-01-19
Also published as: GB202115276D0; CN113355050A

Abstract

Disclosed are a biological formaldehyde-free adhesive, a biological composite material and a preparation method therefor, which relate to the technical field of formaldehyde-free adhesive preparation. The method comprises: performing solid-liquid separation on vinasse, extracting supernatant from the liquid part, and then concentrating to obtain a biological formaldehyde-free adhesive. The vinasse is subject to solid-liquid separation by using separation and extraction technology, and the liquid part of the vinasse containing a large amount of aqueous protein is extracted and concentrated to produce a natural biological formaldehyde-free adhesive. The preparation process for the biological formaldehyde-free adhesive odes not require a crushing and drying process, and the separated liquid part containing the aqueous protein can be directly concentrated to obtain the biological formaldehyde-free adhesive. The biological formaldehyde-free adhesive has good adhesiveness, good water resistance, low costs, and high solid content, and is easy to be widely promote on manmade boards. Since the raw material is a biological fermentation byproduct, the raw material itself is low-carbon, environmentally friendly and sustainable, which has important economic and social benefits for conserving energy and reducing emissions of manmade boards and the entire industrial chain.

Description

A kind of bioformaldehyde-free glue, biocomposite material and preparation method thereof

technical field

The invention relates to the technical field of preparation of formaldehyde-free glue, in particular to a biological formaldehyde-free glue, a biological composite material and a preparation method thereof.

Background technique

Wood-based panels mainly include four categories: plywood, particleboard, blockboard and fiberboard, among which plywood is the leading product of my country's wood-based panels. Since entering the 21st century, China's plywood industry has developed rapidly. While basically meeting the needs of the domestic market, manufacturers have expanded to foreign markets. The competitiveness of domestic plywood in the international market has been significantly enhanced, and the market share has gradually expanded.

At present, except that the building formwork in plywood is made of phenolic glue, the others are made of urea-formaldehyde glue or melamine-modified urea-formaldehyde glue. Only the three-plywood with the lowest amount of glue is used for each standard board. Kilogram. According to statistics, 3/4 of the total amount of adhesives are used for wood processing, mainly trialdehyde glue, which is used in a huge amount. Trialdehyde glue refers to the adhesive prepared from urine aldehyde, phenolic formaldehyde, and melamine formaldehyde as the main raw materials. They and vinyl acetate emulsion form the main force of the adhesive. Their main markets are the wood industry, building decoration, packaging, paper tubes, plywood and cigarettes. Due to the simple production process, convenient use and low price of these glues, there are many manufacturers, and most wood processing factories produce trialdehyde glue.

In recent years, more and more attention has been paid to the harm of formaldehyde. Formaldehyde is a colorless and easily soluble irritating gas, which has great harm to the human body. Wood products made of formaldehyde-containing adhesives are used indoors, and the release period of formaldehyde can be as long as 15 years. Therefore, the pollution of wood-based panels is mainly the release of formaldehyde in the adhesive, and in order to completely solve the problem of free formaldehyde pollution, it is necessary to develop a new type of green formaldehyde-free adhesive.

In addition, the problem of wood shortage has long been highlighted. Under this severe situation, the production of non-wood-based wood-based panels has received extensive attention, such as straw boards. Adhesive is the core of straw board manufacturing and directly affects the performance of the board. At first, the production process of traditional wood particleboard was adopted, and urea-formaldehyde resin was used to produce straw boards. Because the waxy layer on the surface of straw scraps would affect the gluing, the performance of the boards was poor. Later, the use of isocyanate adhesive (MDI) appeared, which was applied in the field of straw wood-based panels. The problem of gluing was better solved, the performance of the board was also improved, and there was no problem of formaldehyde release. The gluing strength was high and the amount of glue used was low. Advantages such as gluing under moisture content. The disadvantage is that MDI also has good bonding properties to inorganic substances. The problem of mold release and separation after heating and forming of products has become a key issue. Because the amount of MDI is low and toxic, special equipment and safety sealing protection are required to ensure production. The content of MDI in ambient air is very low, and it can be evenly mixed with biomass materials. In addition, corresponding measures should be taken in the hot pressing stage to prevent the sticking problem. Measures are: (1) adopt various release agents, and release agents are divided into two types: external release agent and internal release agent. The external release agent realizes the release by pre-preparing a release agent coating on the surface of the heating plate and spraying a liquid auxiliary agent on the upper and lower surfaces of the slab, but the coating needs to be made regularly, which affects the continuity of production. The internal release agent is to mix the release agent, straw and MDI evenly and heat them together, but the release effect is not ideal, and the amount of MDI used is large, which increases the cost. (2) Cover the surface with an isolation layer, and then remove the isolation layer by sanding after the slab is hot-pressed. This method is complex and technically difficult. (3) Add MDI in the middle layer of the slab, and use urea-formaldehyde resin glue or phenolic resin for the upper and lower surface layers. This method has problems such as complex sizing system and poor surface quality, and the effect is not good.

In order to solve the application problem of "trialdehyde" glue, a large number of formaldehyde-free glue appeared on the board market. There are mainly three types: one is to modify the original "trialdehyde" glue to reduce the content of formaldehyde and meet the current The national standard is generally to add substances that can react with formaldehyde, such as increasing the amount of urea or phenol, or adding a small amount of urea, melamine or phenol in the later stage to reduce the content of formaldehyde in the adhesive. Although this method can slow down the formation of formaldehyde The release speed can be achieved in a short time, but the release of formaldehyde is still unavoidable;

The second is to use other types of glue, such as white latex, EVA glue, etc. This type of glue can only be used in wood processing, such as the bonding between wood and wood, but it cannot be used to make plywood. At present, emulsifiable isocyanate (water-based polyurethane) is mainly used in foreign countries to make plywood. This glue does not contain formaldehyde, has high bonding strength and good water resistance. 8 to 10 times of that, the application is limited.

The third is to use renewable natural resources (such as soybean protein powder, tannin, lignin, starch and cellulose, etc.) to modify and develop green and environmentally friendly adhesives suitable for the wood-based panel industry. The adhesives produced by using these resources are low in cost but have defects in performance. If they can achieve the performance of urea-formaldehyde resin adhesives, they can replace urea-formaldehyde resin adhesives.

The first two types belong to the chemical formulations formaldehyde-free glue, and the research at home and abroad in recent years tends to be biological formulations formaldehyde-free glue. At present, the chemical preparation-based formaldehyde-free adhesives on the market include water-based polymer isocyanate adhesives, etc., and the biological preparation-based formaldehyde-free adhesives include formaldehyde-free bean glue, modified starch-based formaldehyde-free adhesives, etc. Bio-glue has the following advantages: low raw material prices; environment-friendly, renewable resources; the development of science and technology has improved the performance of bio-glue, and there are more and more new products. More and more attention has been paid to it, and some countries have set off a research climax on soybean protein glue. The traditional soybean protein glue has poor adhesion, poor water resistance, and high cost. Moreover, the amount of sizing is large, the viscosity is high, and the solid content is low, so it is difficult to popularize it on wood-based panels.

At present, the invention patent of "wood adhesive and its preparation method" discloses a "Honghan formaldehyde-free adhesive", which uses soybean meal as raw material, extracts protein and modifies it, and then adds certain auxiliary materials. Bioengineering technology, the obtained adhesive can achieve the expected bonding strength, and no need to add curing agent when used. However, studies have shown that this material is difficult to reach the quality index of Class I plywood without curing agent, and there are also problems such as mildew and deterioration in other areas of wood-based panels.

Jiangnan University (patent application number: 200510122796.9) discloses a powder bio-adhesive based on soybean protein isolate.

Dehua Rabbit Baby Decoration New Materials Co., Ltd. discloses a formaldehyde-free adhesive for wood-based panels (patent application number: 200510050471.4). It is composed of polyvinyl alcohol, YH-complexing agent, starch, and BPA crosslinking agent. The main agent is prepared by adding materials, adjusting pH value, heating, heat preservation reaction, cooling, and discharging. Polyisocyanate is used as curing agent. . For specific use, mix the main agent with the curing agent isocyanate in a certain proportion and stir evenly. Using the product of the invention, there is no irritating smell in the wood-based panel production workshop, and the wood products such as wood-based panels bonded with it have higher strength than urea-formaldehyde resin and no formaldehyde release, but the price is relatively high.

Sichuan University discloses a flame-retardant formaldehyde-free wood adhesive and a preparation method thereof (patent application number: 200610021957.X). The preparation method provided by the invention is simple, the process is mature, and it is easy to control, but the cohesive force and water resistance need to be improved, and it is not prepared by using natural biological materials.

In view of this, the present invention is proposed.

Contents of the invention

The object of the present invention is to provide a biological formaldehyde-free glue, a biological composite material and a preparation method thereof to solve the above technical problems.

The present invention is achieved like this:

The invention provides a preparation method of biological formaldehyde-free glue, which comprises: solid-liquid separation of distiller's grains to obtain a liquid part, and then concentrating the obtained liquid part to prepare a biological formaldehyde-free glue.

The inventor uses separation and extraction technology to separate solid and liquid from distiller's grains, extract and concentrate the liquid part of distiller's grains containing a large amount of water-based protein, and produce a natural biological formaldehyde-free gum. The preparation process of the biological formaldehyde-free glue does not need crushing and drying processes, and the liquid part of the separated aqueous protein can be directly concentrated to prepare the biological formaldehyde-free glue.

It should be noted that the raw material chosen by the inventors is distiller's grains instead of wine juice, because the inventors found that the liquid part separated from the distiller's grains tends to form a film on the surface of the liquid after drying, and the film is difficult to dissolve in water.

It should be noted that the above-mentioned distiller's grains are not distiller's grains in a dry state, but distiller's grains with water-based protein, and the distiller's grains in a dry state need to be pulverized before they can be gelled. The process is complicated and there is a loss of protein.

In a preferred embodiment of the application of the present invention, the above-mentioned solid-liquid separation is carried out by means of a biological extractor (BIOPROCESSOR), a juice extractor, a filter press, a screw extrusion filter press or a high-speed centrifuge.

Using a biological extractor, through physical screw extrusion, the solid fiber part and liquid part in distiller's grains are separated, and the liquid part is collected.

In a preferred embodiment of the application of the present invention, the above-mentioned liquid part is concentrated according to the solid content, and the methods for concentration include but are not limited to methods such as rotary evaporation, vacuum concentration, vacuum centrifugal concentration, and air blowing.

In a preferred embodiment of the application of the present invention, the distiller's grains are distiller's grains of at least one wine selected from the following: beer, liquor, wine, whiskey, cider, rice wine, industrial alcohol and bioenergy alcohol.

The invention also provides the biological formaldehyde-free glue prepared by the preparation method of the biological formaldehyde-free glue.

In a preferred embodiment of the application of the present invention, the mass proportion of the protein in the biological formaldehyde-free glue is 50-60%, and the mass proportion of the cellulose in the biological formaldehyde-free glue is 40-50%.

The present invention also provides a kind of biocomposite material, the raw material of biocomposite material comprises above-mentioned bioformaldehyde-free glue and filler;

Preferably, the biocomposite material is plywood, particle board, blockboard or fibreboard.

The biological formaldehyde-free glue provided by the invention can be used to manufacture biological composite materials, including formaldehyde-free artificial boards, straw boards and other biomass composite materials.

In a preferred embodiment of the application of the present invention, the above-mentioned filler is selected from at least one of the following materials: wood chips, wood particles, non-wood particles, and biomass materials and straw left after the liquid part is separated from distiller's grains in the process of the present invention ; The mass proportion of the bioformaldehyde-free glue in the biocomposite material is 10-100%;

Preferably, the mass proportion of the biological formaldehyde-free glue in the biocomposite material is 10-95%, more preferably, the proportion is 20-60%, more preferably, the proportion is 20-50%;

Preferably, the mass proportion of the protein in the biocomposite material is 5-30%, preferably, the mass proportion of the protein in the biocomposite material is 5-15%, more preferably, the mass proportion of the protein in the biocomposite material is The ratio is 5-10%.

The above-mentioned wood-based panel products (biocomposite materials) have no added formaldehyde, no toxic organic chemicals, and no organic solvents. They are pressed into panels at a temperature of 100-220 degrees, and at the same time can achieve high solid content (above 50%) and It has a similar viscosity to the current trialdehyde glue, realizes the spray sizing process, and can be used in the manufacture of products including density boards, particle boards, OSB boards, etc. In addition, it can also manufacture non-wood fiber-based wood-based panels, such as straw boards.

Since the raw material is a by-product of biological fermentation, the raw material itself is low-carbon, environmentally friendly and sustainable, which has important economic and social benefits for the energy saving and emission reduction of wood-based panels and the entire industrial chain.

In a preferred embodiment of the application of the present invention, the biocomposite material further includes a curing agent and/or a compatibilizer;

Preferably, the curing agent is selected from at least one of the following curing agents: a solid curing agent and a liquid curing agent.

Examples of solid curing agents include 2-methylimidazole (Imicure AMI-2), 2-phenylimidazole (Curezol 2PZ), 2-phenyl-4-methylimidazole (Curezol 2P4MZ), 2-heptadecylimidazole (Curezol C17Z), 2-phenyl-4,5-dimethylimidazole (Curezol 2PHZ-S), 2,4-diamino-6(2'-methylimidazolyl-(1'))ethyl Diamino-s-triazine (Curezol 2MZ Azine), 2,4-diamino-6(2'-methylimidazolyl-(1'))ethyl-s-triazine, isocyanuric acid (Curezol 2MA -OK), triphenylphosphine, dicyandiamide, 3-phenyl-1,1-dimethylurea, 5-amino-1-naphthol, 8-hydroxyquinoline, polyacrylamide, urea, paraffin , potassium silicate, sodium silicate and the like.

Examples of liquid curing agents include 2-ethyl-4-methylimidazole, 1-benzyl-2-methyl-imidazole, copper(II) naphthenate, cobalt(II) 2-ethylhexanoate, diazo Heterobicycloundecene, N,N-dimethylaniline, N,N-dimethyltoluidine, acrylic acid and the like. The liquid curing agent can be used neat or it can be dissolved in a solvent. The solid curing agent described above may also be dissolved in a suitable solvent to use the curing agent in liquid form.

Where the aforementioned curing agents are in pure liquid or solution form and porous particles are used to trap them, suitable porous particles include, for example, silica, alumina, zeolites, molecular sieves, glass, carbon black, boron nitride, carbonic acid Calcium, clay and polymers, including synthetic high molecular polymers such as polystyrene, polyacrylate, polyvinyl chloride, polyvinyl alcohol, polyvinylpyrrolidone and polyurethane and natural high molecular polymers such as natural Lignin, sulfonated lignin, starch and its modified starch, alginic acid and its salt, chitin and its derivatives such as chitosan, methylcellulose, carboxymethylcellulose and other nanocellulose.

Preferably, the curing agent is selected from acrylic acid crosslinking agent, polyacrylamide crosslinking agent, urea, paraffin, PMDI, glyoxal, potassium silicate, sodium silicate, polyacrylate or its copolymer water-based resin, sulfonate Lignin, carboxymethylcellulose or other nanocellulose.

The compatibilizer is at least one selected from the following surfactants: cationic surfactants, anionic surfactants and nonionic surfactants.

By introducing a polymer material (curing agent) or compatibilizer that can be cured and cross-linked with wood cellulose into the structure of the water-based protein, the compatibilizer can be compounded with other common curing agents to increase the compatibility of the curing agent and wood fiber , to improve mixing uniformity. This can improve the cleanliness and environmental protection of the wood-based panel production and improve the mechanical strength of the wood-based panel. At the same time, it can reduce the amount of glue used, improve the effective utilization rate of the glue, and finally realize energy saving and emission reduction in the wood-based panel industry.

It should be noted that, in one embodiment, other components may be added to the bio-adhesive, including waterproof materials, flame-retardant materials, cross-linking agents, surface-active compatibilizers, defoamers, and the like. The total solid content is 40-60%, which is used to make wood-based panels and other biological composite materials.

Flame retardant materials can be brominated flame retardants, aluminum hydroxide, magnesium hydroxide and silicon-based flame retardants. The cross-linking agent can be DCP, BPO, DTBP, DBHP, double 25, PMDI, etc. Surface active compatibilizers can be cationic surfactants, anionic surfactants, nonionic surfactants, zwitterionic surfactants. The defoamer can be solid particle type, emulsion type, dispersion type, oil type or paste type defoamer.

The present invention also provides a preparation method of biocomposite material, which comprises: mixing raw material bioformaldehyde-free glue and filler, and pressing;

Preferably, the curing agent and/or compatibilizer are mixed with the raw bioformaldehyde-free glue and filler, and then pressed; preferably, the filler is added in an amount of 60-90wt.%.

In an optional embodiment, the amount of filler added refers to the mass percentage of the filler in the total raw material, and the total raw material refers to the general term of curing agent and/or compatibilizer, raw material bioformaldehyde-free glue, and filler.

In an optional embodiment, the amount of filler added is 60wt.%, 70wt.%, 80wt.% or 90wt.%.

Preferably, the pressing includes pre-pressing and hot pressing; pre-pressing is performed in a mold, and hot pressing is performed in a hot press; preferably, the conditions of hot pressing include: 3-10MPa pressure, 120-220°C, Pressing for 3-20 minutes; preferably, hot pressing conditions: 5-10MPa pressure, 150-180°C, pressing for 3-10 minutes.

The present invention has the following beneficial effects:

The invention provides a preparation method of biological formaldehyde-free glue, which uses separation and extraction technology to separate distiller's grains from solid and liquid, extracts and concentrates the liquid part of distiller's grains containing a large amount of water-based protein, and produces a natural biological formaldehyde-free glue. The preparation process of the biological formaldehyde-free glue does not need crushing and drying processes, and the liquid part of the separated aqueous protein can be directly concentrated to prepare the biological formaldehyde-free glue. The bioformaldehyde-free adhesive has good adhesion, good water resistance, low cost and high solid content, and is easy to be popularized on artificial boards in large quantities. Since the raw material is a by-product of biological fermentation, the raw material itself is low-carbon, environmentally friendly and sustainable, which has important economic and social benefits for the energy saving and emission reduction of wood-based panels and the entire industrial chain.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and thus It should be regarded as a limitation on the scope, and those skilled in the art can also obtain other related drawings based on these drawings without creative work.

Fig. 1 is the picture of the biocomposite material that the present invention produces;

Fig. 2 is the bioformaldehyde-free glue produced in Example 1 of the present invention.

detailed description

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Those who do not indicate the specific conditions in the examples are carried out according to the conventional conditions or the conditions suggested by the manufacturer. The reagents or instruments used were not indicated by the manufacturer, and they were all conventional products that could be purchased from the market.

The characteristics and performance of the present invention will be described in further detail below in conjunction with the examples.

Example 1

The present embodiment provides a kind of preparation method of biological formaldehyde-free glue, it comprises the steps:

Take 100 kg of fresh beer dregs and add it to a biological extractor (BIOPROCESSOR). Through physical screw extrusion, the solid fiber part and liquid part in the beer dregs are separated, and 60 kg of liquid and 40 kg of solid fiber are collected. 60 kilograms of liquid parts are left to stand and stored to obtain the supernatant, and the supernatant is separated and concentrated to obtain the viscous liquid part to form the main part of the bioglue of the invention.

After testing, the protein content in the biological formaldehyde-free glue is 50-60wt.%, and the cellulose content is 40-50wt.%.

The biological formaldehyde-free glue prepared in this embodiment is shown in FIG. 2 .

Example 2

Take 100 kg of fresh wine residue, add it to a biological extraction machine (BIOPROCESSOR), and separate the solid fiber part and the liquid part of the wine residue through physical screw extrusion, and collect 60 kg of liquid and 40 kg of solid fiber. 60 kilograms of liquid parts are left standing and stored to obtain a supernatant, and the supernatant is separated and concentrated to obtain a viscous liquid part to form the main part of the bioglue of the invention.

After testing, the protein content in the biological formaldehyde-free glue is 55±5wt.%, and the cellulose content is 45±5wt.%.

Example 3

This example provides a method for preparing biological formaldehyde-free glue. Compared with Example 1, the only difference is that the raw material is different, and the raw material in this example is 100 kg of cider residue.

Example 4

This embodiment provides a biocomposite mat. Specifically, wood chips, wood particles or non-wood particles such as straw were mixed with the bioformaldehyde-free glue prepared in Example 1 (the mixing mass ratio was 80:20), and dried to a water content of about 4%. A cross-linking agent (resin) is then added to the mixture and mixed, and the resulting biocomposite is pre-pressed into a pre-paved mat formed from the biocomposite. Biocomposite mats can be formed into particle board or particle board using conventional heat pressing techniques. (In addition, in other embodiments, it is also possible to mix the cross-linking agent with the bioformaldehyde-free glue, and then mix it with other biomass materials, and then manufacture the formaldehyde-free board).

In the manufacture of particleboard, the proportion of protein-containing bioglue in the biocomposite material can be in the range of 10-100 wt%, preferably in the range of 10-95 wt%, or 20-60 wt%, most preferably 20-50 wt%. The protein content in the biocomposite board may be 5-30 wt%, preferably 5-15 wt%, most preferably 5-10 wt%.

Example 5

A preparation method of artificial fiberboard, mixing wood fiber and the biological formaldehyde-free glue prepared in Example 1, the addition amount of the biological formaldehyde-free glue is 100g; wood fiber 800g. Mixing with crosslinking agent, drying fibers, preforming fiber mats, and finally hot pressing to make fiberboards.

Example 6

This example provides a method for preparing a particle board. In a mixing device, 100 grams of biological glue and 800 grams of wood particles are added. After mixing, the mixture was transferred to a 30 x 30 cm mold and pressed into a matrix. The matrix is then transferred to a heat press. Under 5MPa pressure, press at 200°C for 5 minutes to obtain a particleboard (see Figure 1).

Experimental example 1

In this experimental example, bioformaldehyde-free glue is used to manufacture conventional wood-based panels (particle boards), and the density, internal bonding force, static bending strength and elastic modulus of the wood-based panels are compared.

14 bioformaldehyde-free glues prepared in Example 1 were used as experimental group samples for bonding of (upper) surface layer, core layer and (lower) surface layer, (upper) surface layer, core layer and (lower) surface layer The surface layer corresponds to fine shavings, coarse shavings and fine shavings respectively. Table 1 lists the bioglue weight and the weight (unit, g) of the coarse and fine shavings used in the preparation process of the surface layer and the core layer of the samples of each experimental group, and the addition settings of the crosslinking agent PMDI, water-based polyacrylate and glyoxal three groups, and the control group uses urea-formaldehyde glue as binder to compare the effect of bio-adhesive on the performance of particleboard.

The polypropylene resin is an aqueous polymer emulsion with a solid content of 50% and a pH of 5. PMDI (polymeric isocyanate, molecular weight 2000); glyoxal is (40% aqueous solution of glyoxal).

It can be seen from Table 1 that the particleboard prepared by the biological formaldehyde-free glue provided by the present invention has a large internal bonding force and good bonding performance.

Table 1 Performance test table of particleboard.

Experimental example 2

In this experimental example, wheat straw, distiller's grain biomass extracted from beer residue gum, industrial hemp fiber, and palm fiber were used as raw materials for preparing bio-glue, respectively, and bio-glue was prepared by the method in Example 1, and biomass raw materials and additives were added at the same time. , Additives include the remaining residue of recycled pulp, pulp black liquor (magnesium lignosulfonate MLS), PMDI. The wood-based panels were manufactured according to the formula shown in Table 2, and the density, internal bonding force, static bending strength and elastic modulus of the wood-based panels were detected.

It can be seen from Table 2 that when wheat straw is used as the raw material for the preparation of bio-glue, the density, internal bonding force, static bending strength and elastic modulus of the wood-based panel are better.

Table 2 Performance test table of wood-based panels prepared from different bio-glue raw materials.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

A method for preparing biological formaldehyde-free glue, characterized in that it comprises: separating distiller's grains from solid and liquid, extracting the supernatant from the liquid part and then concentrating to obtain biological formaldehyde-free glue.
The preparation method of biological formaldehyde-free glue according to claim 1, characterized in that, the solid-liquid separation is carried out by means of biological extractor, juicer, filter press, screw extrusion filter press or high-speed centrifuge , to obtain the liquid fraction.
The preparation method of biological formaldehyde-free glue according to claim 1, characterized in that, the liquid part is dehydrated according to the water content and evaporated to obtain a solid content of 15-50%.
The preparation method of biological formaldehyde-free glue according to claim 1 or 3, characterized in that, the distiller's grains are distiller's grains selected from at least one of the following wines: beer, white wine, wine, whiskey, cider, rice wine and industrial Alcohol and bioenergy alcohol.
A biological formaldehyde-free glue prepared by the preparation method of the biological formaldehyde-free glue as described in any one of claims 1-4.
The biological formaldehyde-free glue according to claim 5, characterized in that, the mass proportion of the protein in the biological formaldehyde-free glue is 50-60%, and the mass proportion of the cellulose in the biological formaldehyde-free glue is 40-50%.
A kind of biocomposite material, it is characterized in that, the raw material of described biocomposite material comprises the bioformaldehyde-free glue and filler described in any one of claim 5-6;

Preferably, the biocomposite material is plywood, particle board, blockboard or fiberboard.
The biocomposite material according to claim 7, wherein the filler is selected from at least one of the following materials: wood chips, wood particles, non-wood particles, remaining biomass material and straw after liquid is separated from distiller's grains; The mass proportion of the bioformaldehyde-free glue in the biocomposite material is 10-100%;

Preferably, the mass proportion of the biological formaldehyde-free glue in the biocomposite material is 10-95%, more preferably, the proportion is 20-60%, more preferably, the proportion is 20-50%;

Preferably, the mass proportion of the protein in the biocomposite material is 5-30%, preferably, the mass proportion of the protein in the biocomposite material is 5-15%, more preferably, the biocomposite The proportion of protein in the material is 5-10%.
The biocomposite material according to claim 7 or 8, wherein the biocomposite material further comprises a curing agent and/or a compatibilizer;

Preferably, the curing agent is selected from at least one of the following curing agents: a solid curing agent and a liquid curing agent;

Preferably, the curing agent is selected from acrylic acid crosslinking agent, polyacrylamide crosslinking agent, urea, paraffin, PMDI, glyoxal, potassium silicate, sodium silicate, polyacrylate or its copolymer water-based resin, sulfonate lignin, carboxymethylcellulose or other nanocellulose;

The compatibilizer is selected from at least one of the following surfactants: cationic surfactants, anionic surfactants and nonionic surfactants.
A method for preparing a biocomposite material as claimed in any one of claims 7-9, characterized in that it comprises: mixing raw material bioformaldehyde-free glue and filler, and pressing;

Preferably, the curing agent and/or compatibilizer are mixed with raw bioformaldehyde-free glue and filler, and then pressed; preferably, the filler is added in an amount of 60-90wt.%;

Preferably, the pressing includes pre-pressing and hot pressing; the pre-pressing is carried out in a mold, and the hot pressing is carried out in a hot press; preferably, the conditions of the hot pressing include: 3-10MPa Pressing at 120-220° C. for 3-20 minutes; preferably, the hot pressing conditions include: 5-10 MPa pressure at 150-180° C. for 3-10 minutes.