CN114736507B - Preparation method of biomass-based modified aldehyde-free environment-friendly artificial board adhesive - Google Patents

Abstract

The invention discloses a preparation method of biomass-based modified aldehyde-free environment-friendly artificial board adhesive, which comprises the steps of uniformly mixing lignin and lanthanum niobate to obtain a mixture, then filling the mixture into a transparent PE film packaging bag which can be vacuumized, paving the bag into a thin layer, sealing the bag and vacuumizing the bag, and then irradiating the mixture by taking cobalt 60 as a radiation source according to the irradiation dose of 45-75 kGy; removing the PE film from the irradiated mixture, spraying sterilized deionized water into the mixture, adding lignin degrading enzyme, and uniformly mixing to obtain modified lignin; then weighing the following components in parts by weight: 100 parts of MDI glue, 15-25 parts of modified lignin, 5-12 parts of inorganic powder and 3-8 parts of diluent; and then sequentially adding the biomass-based modified aldehyde-free environment-friendly artificial board adhesive into a drum-type glue mixer to be stirred and mixed to obtain the biomass-based modified aldehyde-free environment-friendly artificial board adhesive, wherein the problems that the adhesive is not easy to disperse on the surface of the wood shavings and the adhesive application amount is high can be solved by the composite environment-friendly artificial board adhesive.

Description

A kind of preparation method of biomass-based modified formaldehyde-free environment-friendly wood-based panel adhesive

technical field

The invention belongs to the technical field of wood-based panel adhesives, and in particular relates to a preparation method of a biomass-based modified aldehyde-free environment-friendly wood-based panel adhesive.

Background technique

In recent years, the wood-based panel application market has a strong pursuit of green formaldehyde-free sheets. The current formaldehyde-free glue that can be used in industrial applications is diphenylmethane diisocyanate (MDI) glue. Many wood-based panel companies have begun to use MDI glue to prepare Wood-based panels have reached the requirements of green and formaldehyde-free. In the traditional wood-based panel preparation process, the amount of MDI glue accounts for about 13 to 15% of the weight of the entire panel, accounting for more than 50% of the production cost of wood-based panels, which is a decisive factor affecting the market competitiveness of wood-based panels; by compounding other environmentally friendly adhesives On the basis of maintaining the original performance of wood-based panels, reducing the cost proportion of wood-based panel adhesives is the key to promoting the large-scale application of formaldehyde-free particleboards.

In addition, the viscosity of a single MDI is high. When it is mixed with particleboard, the MDI glue is not easy to disperse on the surface of the shavings, which is easy to cause uneven adhesion. After hot pressing, it will cause uneven internal stress of the oriented strand board and split The phenomenon of delamination severely limits the application of particleboard. Therefore, it has become a research hotspot to develop a wood-based panel adhesive that is environmentally friendly, safe, low in sizing, and can be evenly dispersed on the surface of the shavings.

SUMMARY OF THE INVENTION

In view of the above deficiencies, the present invention discloses a preparation method of a biomass-based modified formaldehyde-free environment-friendly wood-based panel adhesive, which produces a composite environment-friendly wood-based panel adhesive, which solves the problem that the adhesive is not easy to disperse and apply on the surface of the shavings. High glue problem.

The present invention adopts following technical scheme to realize:

A preparation method of a biomass-based modified formaldehyde-free environment-friendly wood-based panel adhesive, comprising the following steps:

(1) Take the lignin and lanthanum niobic acid and mix them uniformly to obtain a mixture, the weight ratio of the lignin and lanthanum niobic acid is 100: (0.2-1), and then put the mixture into a transparent PE film packaging bag that can be vacuumized , after paving into a thin layer with a thickness of 1.5cm-2cm, sealing and vacuuming, and then using cobalt 60 as a radiation source, the mixture is irradiated at a dose of 45-75kGy; the irradiated mixture is irradiated. Transfer to a clean workshop with positive pressure, and remove the PE film, then spray the mixture with sterilized deionized water, the weight of the deionized water is 10-15% of the weight of the lignin, and then add the lignin After the degrading enzymes are evenly mixed, they are placed at 25 to 35° C. for 48 to 72 hours to obtain modified lignin, and the weight ratio of the lignin to the lignin degrading enzymes is 500: (1 to 2);

(2) Weigh the following components in parts by weight: 100 parts of MDI glue, 15-25 parts of modified lignin, 5-12 parts of inorganic powder, and 3-8 parts of diluent; In the machine, and then stirring at a speed of 100r/min for 5-10 minutes, the biomass-based modified formaldehyde-free environmentally friendly wood-based board adhesive is obtained, and then mixed with particleboard within 30 minutes to complete the sizing.

Lignin is a biopolymer with a three-dimensional network structure formed by the interconnection of three phenylpropane units through ether bonds and carbon-carbon bonds. It contains abundant active groups such as aromatic ring structure, aliphatic and aromatic hydroxyl groups, and quinone groups . At present, the main way of obtaining lignin is extraction from pulp waste liquid. Under the action of alkali, lignin undergoes a certain degree of alkaline hydrolysis, which increases its solubility, and is extracted and separated by precipitation. The obtained lignin is called alkali lignin; the lignin obtained by klason method is called klason. Lignin; thiolignin extracted from kraft pulp; sulfonated lignin extracted from sulfite pulp, mainly in the form of calcium lignosulfonate and sodium lignosulfonate. Lignin can be slowly degraded in specific fungi, bacteria and corresponding microbial communities to form lignin molecular chain fragments, aromatic compounds, and even carbon dioxide and water. The degradation process mainly relies on the non-specific oxidation reaction of a series of lignin-degrading enzymes, including lignin peroxidase, manganese peroxidase and laccase.

To sum up, lignin is an amorphous thermoplastic polymer with no melting point, but has glass transition properties. Under certain pressure, lignin will soften and have fluidity and adhesiveness. Excellent performance adhesive. However, lignin is a polyphenolic polymer compound, a large number of active groups are wrapped in the molecule, the intermolecular interaction is strong, the aromatic ring structure is intertwined into a network, and there are defects such as low reactivity, high softening temperature point, and poor fluidity; To this end, the present invention modifies lignin to obtain lignin molecular segments with high mobility and reactivity. First, lignin and lanthanum niobate are mixed, because lanthanum niobate is a perovskite structure. The layered metal oxide, which shows stronger acidity than other similar metal oxide materials, has excellent potential in the field of photocatalyst materials, and then uses PE plastic film to isolate lignin from oxygen and bacteria, The radioactive isotope cobalt 60 is used to generate γ-rays to pretreat lignin. On the one hand, bactericidal treatment of lignin can minimize the reduction of bacteria such as Escherichia coli, Staphylococcus aureus, Salmonella, Candida, and Aspergillus niger. Interfere with the enzymatic hydrolysis reaction of lignin and hemicellulose in the next step; on the other hand, the lamellar lanthanum niobate catalyst is added to the lignin powder, under the action of γ-rays, it can catalyze the molecular chain of lignin. Part of the C-O bond is broken, and on the basis of reducing the molecular weight of lignin, more lignin molecular segments with active groups are formed.

At the same time, the lignin products extracted in the pulping process are generally difficult to achieve complete separation of lignin and hemicellulose due to the formation of stable covalent bonds between hemicellulose and lignin, most of which are lignin. - Hemicellulose complex. Therefore, in the present invention, after the lignin is irradiated, the lignin is degraded by the lignin peroxidase/laccase complex enzyme to form a series of lignin molecular segments with low molecular weight, polyhydroxyl and polyaldehyde group structures, Thereby, the purpose of increasing the fluidity of lignin under high temperature conditions and improving its reactivity with MDI glue and hydroxyl groups on the surface of shavings is achieved.

Talc powder is an industrial product. The general boundary grade of talc powder (including talc) is 35% and the industrial grade is 50%. Cost and large-scale resource utilization methods are the main pollution sources of mines. In order to solve this problem, the present invention adds talc tailings powder to the adhesive, because talc has anti-caking effect, it can be used as a release agent and anti-sticking agent, and adding talc tailings powder can reduce the glue The apparent viscosity of the adhesive avoids the phenomenon that the adhesive is not easily dispersed and adheres unevenly on the surface of the shavings due to the excessively high adhesive viscosity during the spraying process; on the other hand, the talc tailings powder can be fully filled into the shavings. In the gap, the stress defect of the particleboard is reduced and the mechanical strength is improved.

At the same time, the present invention mixes propylene glycol, diethylene glycol, paraffin and water in proportion to prepare a diluent and add it to the adhesive. On the one hand, it can reduce the viscosity of the MDI glue according to its own characteristics as a solvent. Improve the uniformity of sizing; at the same time, propylene glycol and diethylene glycol in the diluent components, due to their active hydroxyl groups, can be used as a "bridge" between the MDI glue and lignin, by forming a more complex network cross-linked The structure improves the bonding properties of adhesives and the water resistance of particleboard products.

The MDI glue is any one of WANNATE® CW-20, WANNATE® PM300 and WANNATE® PM-200 of Wanhua Chemical.

Further, the lignin includes any one of alkali lignin, acid-soluble lignin, Klason lignin, thiolignin, sodium lignosulfonate and calcium lignosulfonate; preferably alkali lignin and Klason lignin any of the elements.

Further, the lanthanum niobate has a lamellar structure, and the structural molecular formula is HLaNb ₂ O ₇ .

Further, the lignin degrading enzyme is a composite enzyme obtained by mixing lignin peroxidase and laccase, and in the composite enzyme, the weight ratio of the lignin peroxidase and laccase is (1 ~3): 1.

Further, the inorganic powder is talc tailings with a particle size of 400 mesh to 600 meshes, the talc tailings contain more than 20wt% talc, and the talc tailings also contain dolomite, quartzite, green mud Any one or more components of stone and calcite.

Further, the diluent is formed by mixing propylene glycol, diethylene glycol, paraffin and water, and the weight ratio of the propylene glycol, diethylene glycol, paraffin and water is 1:2:2:5 .

Compared with the prior art, the technical solution has the following beneficial effects:

1. Lignin is a renewable polymer, mainly present in pulping waste liquid, and is a natural adhesive. The present invention prepares an adhesive for wood-based panel production by modifying and pre-processing lignin, and then mixing it with MDI glue, inorganic powder and diluent, which can reduce the chemical synthesis and non-renewable based on chemical synthesis to a certain extent. The amount of MDI glue used, but also has the characteristics of safety, green and environmental protection.

2. The reaction of the lignin modification method of the present invention is milder, and the conventional lignin activation reaction generally needs to be reacted for more than 2 to 5 hours at a temperature of more than 200 ° C under harsh conditions such as organic solvents, high temperature, and H ₂ atmosphere. A better product is obtained. The invention adopts the irradiation-enzymatic hydrolysis modification method to obtain lignin molecular segments with low molecular weight, high activity and high fluidity under mild conditions.

3. The adhesive effect produced by the present invention is more excellent. By adding materials such as modified lignin, talc tailings and diluent, the viscosity of the adhesive can be effectively reduced, and a complex network polymer structure can be generated, thereby improving the application of the adhesive. The uniformity of the glue and the adhesive performance of the adhesive, and the process is simple and the operability is strong.

Detailed ways

The following examples further illustrate the present invention, but are not intended to limit the present invention. The unremarked specific experimental conditions and methods in the following examples, the adopted technical means are usually conventional means well known to those skilled in the art.

Example 1:

A preparation method of a biomass-based modified formaldehyde-free environment-friendly wood-based panel adhesive, comprising the following steps:

(1) Take the lignin and lanthanum niobic acid and mix them evenly to obtain a mixture, the weight ratio of the lignin and lanthanum niobic acid is 100:0.4, and then put the mixture into a transparent PE film packaging bag that can be vacuumized, and flatten it into a After a thin layer with a thickness of 1.75cm, it was sealed and air-treated to -0.1 Mpa, and then the mixture was irradiated at a dose of 55kGy with cobalt 60 as the radiation source; the irradiated mixture was transferred to a positive Press the clean workshop, remove the PE film, then spray the mixture with sterilized deionized water, the weight of the deionized water is 12% of the weight of the lignin, then add the lignin degrading enzyme and mix it evenly. The modified lignin is obtained by placing it at 28°C for 56 hours, and the weight ratio of the lignin and the lignin degrading enzyme is 500:1.2; the lignin is Klason lignin; the lanthanum niobic acid has a lamellar structure , the structural molecular formula is HLaNb ₂ O ₇ ; the lignin degrading enzyme is a composite enzyme obtained by mixing lignin peroxidase and laccase, in the composite enzyme, the lignin peroxidase and laccase The weight ratio is 1.85:1;

(2) Weigh the following components in parts by weight: 100 parts of MDI glue, 19 parts of modified lignin, 8 parts of inorganic powder, and 5.5 parts of diluent; 8 min of stirring at a speed of /min to obtain biomass-based modified formaldehyde-free environment-friendly wood-based panel adhesive, which is then mixed with particleboard within 30 min to complete sizing; the MDI adhesive is WANNATE from Wanhua Chemical. ®CW-20; the inorganic powder is talc tailings with a particle size of 450 meshes, the talc tailings contain 30wt% talc, and the talc tailings also contain dolomite and quartz; the dilution The agent is composed of propylene glycol, diethylene glycol, paraffin and water, and the weight ratio of the propylene glycol, diethylene glycol, paraffin and water is 1:2:2:5.

Example 2:

A preparation method of a biomass-based modified formaldehyde-free environment-friendly wood-based panel adhesive, comprising the following steps:

(1) Take the lignin and lanthanum niobic acid and mix them evenly to obtain a mixture, the weight ratio of the lignin and lanthanum niobic acid is 100:0.2, and then put the mixture into a transparent PE film packaging bag that can be vacuumized, and flatten it into a After a thin layer with a thickness of 1.5cm, it is sealed and air-treated to -0.08Mpa, and then the mixture is irradiated at a dose of 45kGy with cobalt 60 as the radiation source; the irradiated mixture is transferred to a positive Pressed clean workshop, and remove the PE film, then spray the mixture with sterilized deionized water, the weight of the deionized water is 10% of the weight of the lignin, and then add the lignin degrading enzyme and mix evenly. The modified lignin is obtained by placing it at 25°C for 48 hours, and the weight ratio of the lignin and the lignin degrading enzyme is 500:1; the lignin is thiolignin; the lanthanum niobate is lamellar structure, the structural formula is HLaNb ₂ O ₇ ; the lignin degrading enzyme is a composite enzyme obtained by mixing lignin peroxidase and laccase, in the composite enzyme, the lignin peroxidase and laccase The weight ratio of enzymes is 1:1;

(2) Weigh the following components by weight: 100 parts of MDI glue, 15 parts of modified lignin, 5 parts of inorganic powder, and 3 parts of diluent; /min speed stirring for 5min, that is, biomass-based modified aldehyde-free environment-friendly wood-based board adhesive is obtained, and then mixed with particleboard within 30min to complete the sizing; the MDI glue is Wanhua Chemical's WANNATE® CW-20; the inorganic powder is talc tailings with a particle size of 400 meshes, the talc tailings contain 30wt% talc, and the talc tailings also contain calcite; the diluent is composed of propylene glycol, a Diethylene glycol, paraffin and water are mixed and formed, and the weight ratio of the propylene glycol, diethylene glycol, paraffin and water is 1:2:2:5.

Example 3:

A preparation method of a biomass-based modified formaldehyde-free environment-friendly wood-based panel adhesive, comprising the following steps:

(1) Take lignin and lanthanum niobic acid and mix them uniformly to obtain a mixture, the weight ratio of the lignin and lanthanum niobic acid is 100:0.8, and then put the mixture into a transparent PE film packaging bag that can be vacuumized, and flatten it into a After a thin layer with a thickness of 1.9cm, it is sealed and air-treated to -0.1Mpa, and then cobalt 60 is used as a radiation source to irradiate the mixture at a dose of 65kGy; the irradiated mixture is transferred to a positive Press the clean workshop, remove the PE film, then spray the mixture with sterilized deionized water, the weight of the deionized water is 14% of the weight of the lignin, and then add the lignin degrading enzyme and mix evenly. The modified lignin is obtained by placing it at 32°C for 64 hours, and the weight ratio of the lignin and the lignin degrading enzyme is 500:1.8; the lignin is acid-soluble lignin; the lanthanum niobate is lamellar structure, the structural molecular formula is HLaNb ₂ O ₇ ; the lignin degrading enzyme is a composite enzyme obtained by mixing lignin peroxidase and laccase, in the composite enzyme, the lignin peroxidase and laccase The weight ratio of enzymes is 2.5:1;

(2) Weigh the following components by weight: 100 parts of MDI glue, 22 parts of modified lignin, 10 parts of inorganic powder, and 7 parts of diluent; 8 minutes of stirring at a speed of /min to obtain biomass-based modified formaldehyde-free environmentally friendly wood-based board adhesive, which is then mixed with particleboard within 30 minutes to complete the sizing; the MDI glue is Wanhua Chemical's WANNATE® PM-200; the inorganic powder is talc tailings with a particle size of 500 meshes, the talc tailings contain 32wt% talc, and the talc tailings also contain dolomite, quartzite and calcite; the The diluent is composed of propylene glycol, diethylene glycol, paraffin and water, and the weight ratio of the propylene glycol, diethylene glycol, paraffin and water is 1:2:2:5.

Example 4:

A preparation method of a biomass-based modified formaldehyde-free environment-friendly wood-based panel adhesive, comprising the following steps:

(1) Take the lignin and lanthanum niobic acid and mix them evenly to obtain a mixture, the weight ratio of the lignin and lanthanum niobic acid is 100:1, and then put the mixture into a transparent PE film packaging bag that can be vacuumized, and flatten it into a After a thin layer with a thickness of 2cm, it is sealed and air-treated to -0.15Mpa, and then the mixture is irradiated at a dose of 75kGy with cobalt 60 as the radiation source; the irradiated mixture is transferred to a positive pressure clean workshop, and remove the PE film, then spray the mixture into sterilized deionized water, the weight of the deionized water is 15% of the weight of the lignin, then add the lignin degrading enzyme and mix evenly at 35 The modified lignin is obtained by placing it at ℃ for 72 hours, and the weight ratio of the lignin and the lignin degrading enzyme is 500:2; the lignin is alkali lignin; the lanthanum niobate has a lamellar structure, The structural molecular formula is HLaNb ₂ O ₇ ; the lignin degrading enzyme is a composite enzyme obtained by mixing lignin peroxidase and laccase, in the composite enzyme, the lignin peroxidase and laccase are The weight ratio is 3:1;

(2) Weigh the following components by weight: 100 parts of MDI glue, 25 parts of modified lignin, 12 parts of inorganic powder, and 8 parts of diluent; 10 min of stirring at a speed of /min to obtain a biomass-based modified formaldehyde-free environment-friendly wood-based panel adhesive, which is then mixed with particleboard within 30 min to complete the sizing; the MDI adhesive is WANNATE from Wanhua Chemical. ® PM300; the inorganic powder is talc tailings with a particle size of 400 meshes to 600 meshes, the talc tailings contain 40wt% talc, and the talc tailings also contain dolomite and quartz; the The diluent is composed of propylene glycol, diethylene glycol, paraffin and water, and the weight ratio of the propylene glycol, diethylene glycol, paraffin and water is 1:2:2:5.

Example 5:

A preparation method of a biomass-based modified formaldehyde-free environment-friendly wood-based panel adhesive, comprising the following steps:

(1) Take lignin and lanthanum niobic acid and mix them uniformly to obtain a mixture, the weight ratio of the lignin and lanthanum niobic acid is 100:0.8, and then put the mixture into a transparent PE film packaging bag that can be vacuumized, and flatten it into a After a thin layer with a thickness of 1.8cm, it was sealed and air-treated to -0.1 Mpa, and then the mixture was irradiated at a dose of 60kGy with cobalt 60 as the radiation source; the irradiated mixture was transferred to a positive Press the clean workshop, remove the PE film, spray the mixture with sterilized deionized water, the weight of the deionized water is 12.5% of the weight of the lignin, then add the lignin degrading enzyme and mix it evenly. The modified lignin is obtained by placing it at 30°C for 60 hours, and the weight ratio of the lignin to the lignin degrading enzyme is 500:2; the lignin is Klason lignin; the lanthanum niobate has a lamellar structure , the structural molecular formula is HLaNb ₂ O ₇ ; the lignin degrading enzyme is a composite enzyme obtained by mixing lignin peroxidase and laccase, in the composite enzyme, the lignin peroxidase and laccase The weight ratio of 2.5:1;

(2) Weigh the following components by weight: 100 parts of MDI glue, 20 parts of modified lignin, 8 parts of inorganic powder, and 5 parts of diluent; 10 min of stirring at a speed of /min to obtain a biomass-based modified formaldehyde-free environment-friendly wood-based panel adhesive, which is then mixed with particleboard within 30 min to complete the sizing; the MDI adhesive is WANNATE from Wanhua Chemical. ®CW-20; the inorganic powder is talc tailings with a particle size of 600 meshes, the talc tailings contain 35wt% talc, and the talc tailings also contain dolomite; the diluent is composed of propylene glycol , diethylene glycol, paraffin and water are mixed and formed, and the weight ratio of the propylene glycol, diethylene glycol, paraffin and water is 1:2:2:5.

Comparative Example 1:

The only difference between this comparative example and the preparation method described in Example 5 is that lanthanum niobate is not added in step (1), and other steps and methods remain unchanged.

Comparative Example 2:

The only difference between this comparative example and the preparation method described in Example 5 is that, in step (1), without radiation treatment, lignin and lanthanum niobic acid are mixed, and then sterilized deionized water and lignin are added in sequence to degrade Enzymes modify lignin.

Comparative Example 3:

The only difference between this comparative example and the preparation method described in Example 5 is that, in step (1), after the lignin is irradiated, sterilized deionized water and lignin-degrading enzymes are not added for treatment.

Comparative Example 4:

The only difference between this comparative example and the preparation method described in Example 5 is that in step (2), without adding inorganic powder, directly mixing the same proportion of MDI glue, modified lignin and diluent to prepare an adhesive.

Comparative Example 5:

The difference between this comparative example and the preparation method described in Example 5 is only that, in step (2), the diluent is obtained by mixing paraffin and water in a weight ratio of 3:7.

Experimental example:

The modified lignin and adhesive products were prepared according to the preparation methods described in Examples 1 to 5 and Comparative Examples 1 to 5, and the performance tests of the modified lignin and the adhesive were carried out according to the following methods. The specific results are shown in Table 1:

1. Determination of lignin structure:

(1) The phenolic hydroxyl content of lignin was determined according to the following literature: Wu Baoguo, Zhao Julan, Du Jingbin. Determination of phenolic hydroxyl content of lignin by differential ultraviolet spectroscopy [J]. Journal of Northeast Forestry University, 1993, 02 (21), 58 ~65;

(2) The molecular weight and molecular weight distribution of lignin were measured by Waters 1515/2414 gel permeation chromatograph. The test column temperature was kept at 40°C and the flow rate was 1 ml/min. Three Waters chromatographic columns (Styragel HR1, HR3 and HR4) were connected in series. ), DMF as mobile phase, German PSS polystyrene as standard sample (Mp= 246000, 184000, 120000, 44200, 18200, 9890, 6520, 2770, 890, 474, 370, PDI＜1.20);

(3) The glass transition temperature of lignin was measured by the Q20 differential scanning calorimetry of TA Company, and the test was carried out in a N ₂ atmosphere at a heating rate of 10 °C/min.

2. Determination of adhesive properties:

Particleboards with a thickness of 18 ± 1 mm were prepared according to the standard production process for load-bearing particleboards (P3), with an amount of adhesive of 11.5% of the particle weight. According to the national standard of particleboard, the static bending strength (MOR), elastic modulus (MOE), internal bonding strength and 24-hour water absorption thickness expansion rate of the product in dry state were determined.

Table 1 Modified lignin structure and performance results of adhesive products obtained by different preparation methods

It can be seen from the above data that the adhesive prepared according to the method of the present invention can obtain better technical effects during use, and is more uniformly mixed with particleboard, thereby improving the product performance of particleboard.

In addition, it should be understood that although this specification is described in terms of embodiments, not each embodiment only includes an independent technical solution, and this description in the specification is only for the sake of clarity, and those skilled in the art should take the specification as a whole , the technical solutions in each embodiment can also be appropriately combined to form other implementations that can be understood by those skilled in the art.

Claims (6)

1. A preparation method of biomass-based modified aldehyde-free environment-friendly artificial board adhesive is characterized by comprising the following steps: the method comprises the following steps:

(1) Uniformly mixing lignin and lanthanum niobic acid to obtain a mixture, wherein the weight ratio of the lignin to the lanthanum niobic acid is 100 (0.2-1), then filling the mixture into a transparent PE film packaging bag which can be vacuumized, spreading the mixture into a thin layer with the thickness of 1.5 cm-2 cm, sealing and vacuumizing the thin layer, and then performing irradiation treatment on the mixture according to the irradiation dose of 45-75 kGy by taking cobalt 60 as a radiation source; transferring the mixture after irradiation treatment to a clean workshop with positive pressure, removing the PE film, spraying sterilized deionized water into the mixture, wherein the weight of the deionized water is 10-15% of the weight of the lignin, then adding lignin degrading enzyme, uniformly mixing, and then placing at 25-35 ℃ for 48-72 hours to obtain the modified lignin, wherein the weight ratio of the lignin to the lignin degrading enzyme is 500 (1-2);

(2) Weighing the following components in parts by weight: 100 parts of MDI glue, 15-25 parts of modified lignin, 5-12 parts of inorganic powder and 3-8 parts of diluent; and sequentially adding the biomass-based modified aldehyde-free environment-friendly artificial board adhesive into a drum-type glue mixer, stirring at the speed of 100r/min for 5-10 min to obtain the biomass-based modified aldehyde-free environment-friendly artificial board adhesive, and uniformly mixing the biomass-based modified aldehyde-free environment-friendly artificial board adhesive with a particle board within 30min to finish gluing.

2. The preparation method of the biomass-based modified aldehyde-free environment-friendly artificial board adhesive according to claim 1, which is characterized by comprising the following steps: the lignin comprises any one of alkali lignin, acid soluble lignin, klason lignin, thiolignin, sodium lignosulfonate and calcium lignosulfonate.

3. The preparation method of the biomass-based modified aldehyde-free environment-friendly artificial board adhesive according to claim 1, which is characterized by comprising the following steps: the lanthanum niobic acid is of a lamellar structure, and the structural molecular formula is HLaNb ₂ O ₇ 。

4. The preparation method of the biomass-based modified aldehyde-free environment-friendly artificial board adhesive according to claim 1, which is characterized by comprising the following steps: the lignin degrading enzyme is a composite enzyme obtained by mixing lignin peroxidase and laccase, and the weight ratio of the lignin peroxidase to the laccase in the composite enzyme is (1-3) to 1.

5. The preparation method of the biomass-based modified aldehyde-free environment-friendly artificial board adhesive according to claim 1, which is characterized by comprising the following steps: the inorganic powder is talc tailings with the grain size of 400-600 meshes, the talc tailings contain more than 20wt% of talc, and the talc tailings also contain one or more of dolomite, quartz, chlorite and calcite.

6. The preparation method of the biomass-based modified aldehyde-free environment-friendly artificial board adhesive according to claim 1, which is characterized by comprising the following steps: the diluent is prepared by mixing propylene glycol, diethylene glycol, paraffin and water, wherein the weight ratio of the propylene glycol to the diethylene glycol to the paraffin to the water is 1.