WO2023208015A1 - 从木质生物质提取木质素作为胶黏剂的方法 - Google Patents

从木质生物质提取木质素作为胶黏剂的方法 Download PDF

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Publication number
WO2023208015A1
WO2023208015A1 PCT/CN2023/090745 CN2023090745W WO2023208015A1 WO 2023208015 A1 WO2023208015 A1 WO 2023208015A1 CN 2023090745 W CN2023090745 W CN 2023090745W WO 2023208015 A1 WO2023208015 A1 WO 2023208015A1
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Prior art keywords
lignin
adhesive
solvent
plywood
woody biomass
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PCT/CN2023/090745
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English (en)
French (fr)
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李帅
罗小林
杨光绪
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山东百沃生物科技有限公司
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Publication of WO2023208015A1 publication Critical patent/WO2023208015A1/zh

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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J197/00—Adhesives based on lignin-containing materials
    • C09J197/005—Lignin
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08H—DERIVATIVES OF NATURAL MACROMOLECULAR COMPOUNDS
    • C08H6/00—Macromolecular compounds derived from lignin, e.g. tannins, humic acids
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E50/00—Technologies for the production of fuel of non-fossil origin
    • Y02E50/10—Biofuels, e.g. bio-diesel

Definitions

  • the invention belongs to the technical field of efficient utilization of lignin, and specifically relates to a method for extracting active lignin from woody biomass as an adhesive, and an adhesive obtained by this method.
  • lignin is the most abundant aromatic natural polymer compound on earth.
  • lignin plays a role in binding cellulose together in plants. While improving the rigidity of plants, the refractory aromatic ring structure in lignin also plays a role in resisting the invasion of external pests and diseases.
  • Lignin also known as lignin
  • lignin is mainly formed by three precursors (p-coumaryl alcohol, coniferyl alcohol and sinapyl alcohol) through phenol hydroxyl oxidative radicalization, free radical delocalization and free radical multi-stage coupling reactions.
  • a type of polymer compound with multiple connecting bonds According to different active free radical sites generated by free radical delocalization, CO (such as ⁇ –O–4, 4–O–5, etc.) and C–C (such as 5-5, ⁇ –5, etc.) can be formed between lignin units. and ⁇ – ⁇ , etc.).
  • CO such as ⁇ –O–4, 4–O–5, etc.
  • C–C such as 5-5, ⁇ –5, etc.
  • the synthesis pathway, structure and types of connecting bonds between units of lignin are as follows:
  • the acid or alkali used in the reaction medium can catalyze the breakage of C-O bonds and increase the dissolution rate of lignin in woody biomass
  • the catalyst or high temperature also promotes lignin degradation products.
  • the re-condensation causes cross-linking between lignin units to produce a new C-C connection structure. This separated condensed lignin cannot be condensed and cross-linked again at high temperatures. .
  • the existing technology is mainly based on the lignin unit containing a phenol structure, using lignin to replace phenol to synthesize phenolic resin adhesive under alkaline conditions and hot-pressing and curing under alkaline conditions.
  • Lignin can self-crosslink under acidic conditions to produce all-lignin-based adhesives.
  • the main synthesis route of phenolic resin adhesive is that phenol and formaldehyde form a prepolymer under alkaline conditions, that is, the adhesive.
  • the reaction mainly involves the hydroxymethylation of phenol and the re-condensation of hydroxymethyl and phenol to form phenol units. methylene bridged structure.
  • hydroxymethylation mainly occurs at the ortho- and para-positions of the phenolic hydroxyl group; in the phenol unit of lignin, the para-position of the phenolic hydroxyl group has been occupied by alkyl side chains, and part of the ortho-position has also been occupied by Occupied by the methoxy group. Therefore, when lignin replaces phenol to synthesize phenolic resin, due to its few active sites, the synthesized resin has poor adhesive properties. When the lignin addition ratio exceeds about 30%, the performance of the synthesized adhesive drops sharply. In addition, the condensation of lignin results in low lignin reactivity.
  • lignin-phenol-formaldehyde resin adhesives contain a large amount of unreacted free formaldehyde. After being used as adhesives, they often release a large amount of formaldehyde, causing formaldehyde exceeding the standard and other issues of major concern to consumers.
  • the present invention provides a method for separating and extracting active lignin from lignin-containing woody biomass for use as wood adhesives, especially using it directly as a wood adhesive.
  • Wood Adhesive Method The active lignin extracted by the present invention can be compounded with solvents and auxiliaries and applied to the wood surface as a full lignin-based adhesive, and the lignin itself can be condensed and cross-linked through hot pressing, thereby bonding the wood to the surface.
  • a method of extracting lignin from woody biomass as an adhesive includes the following steps:
  • the pH value is 0-3, mix the lignin-containing woody biomass, the modifier and the first solvent, heat it to 70-180 degrees Celsius for reaction, and separate the resulting reaction liquid.
  • the modification The agents are formaldehyde, trimerformaldehyde, paraformaldehyde, One or more of acetaldehyde, paraldehyde, paraacetaldehyde, propionaldehyde, butyraldehyde, benzaldehyde, furfural, acetone, butanone, the added mass is 0.3%-200% of the woody biomass mass; change
  • the carbonyl group in the sex agent can react with the phenolic hydroxyl group in the meta position of the lignin unit to form a hydroxyalkyl group.
  • This reaction inhibits the self-condensation reaction of lignin during the extraction process by occupying or consuming the meta position of the phenol unit.
  • the hydroxyalkyl groups formed provide new active cross-linking sites for subsequent hot-pressure cross-linking of lignin;
  • step (3) (4) Mix the solid obtained in step (3) with the second solvent and use it as an adhesive.
  • the adhesive in step (4) is evenly applied to the wood surface, and is cured and cross-linked by hot pressing at a certain temperature.
  • This all-lignin-based adhesive can be directly applied in areas where curing and bonding can be achieved by hot pressing without further reaction or adding other active ingredients.
  • These applications are not limited to the preparation of plywood, fiberboard, particleboard, bamboo-wood composite board, etc.; In actual applications, the hot pressing temperature can be adjusted according to actual needs (such as plate thickness, moisture, etc.).
  • the hot-press curing cross-linking temperature is 100-220°C, preferably 110-200°C, more preferably 120-180°C, more preferably 130-170°C.
  • the first solvent in step (1) is a mixed solvent of an organic solvent and water, wherein the organic solvent is 1,4-epoxybutane, 1,4-dioxane, and 4-methylbutyrolactone. , 2-methyltetrahydrofuran, methanol, ethanol, propanol, butanol, one or more of formic acid, acetic acid, acetone, butanone, accounting for 40%-95% of the total mass of the first solvent.
  • the above-mentioned organic solvent and water are mixed in proportion to obtain the first solvent, which is used as an excellent solvent for lignin.
  • this solvent in the lignin extraction process is beneficial to dissolving the lignin in the woody biomass, so that the lignin can be mixed with the solvent.
  • the modifier reacts quickly, thereby inhibiting the re-condensation of lignin.
  • the addition amount of the first solvent in step (1) is 3-20 times the mass of the woody biomass in step (1), preferably 4-15 times, more preferably 5-10 times; this addition amount is for the batch type. Reaction kettle, in actual application process, if continuous cooking or extraction reactor is used, the addition amount can be adjusted as needed.
  • the second solvent in step (4) is one of water, methanol, ethanol, acetone, butanone, 1,4-epoxybutane, 2-methyltetrahydrofuran, and 1,4-dioxane. or more, and its main function is to uniformly disperse the solid form of lignin separated in step (3), so as to facilitate the even application of adhesive to the wood surface that needs to be bonded.
  • the added amount of the solvent is 0.5-10 times the dry weight of the solid described in step (3), preferably 1-6 times, and more preferably 2-4 times.
  • the amount of solvent added can adjust the amount of subsequent adhesive sizing; when adding more solvent to configure a low-concentration adhesive, the amount of sizing can be increased to achieve better adhesive effects, and when adding less solvent to configure it When using a high concentration of adhesive, a smaller amount of glue can achieve better results.
  • an auxiliary agent is added to the mixture of the solid and the second solvent.
  • the auxiliary agent is one or more of an acid, a thickener, and a dispersant.
  • step (2) part or all of the first solvent is concentrated and removed before adding water for mixing; concentrating and removing the solvent can reduce the amount of water added, which is beneficial to the precipitation of lignin into a solid suspension.
  • the reaction time of step (1) is 0.1-10 hours. When the temperature used is higher, the reaction time is shorter. When the preferred temperature is 70-80°C, the reaction time is 4-10 hours; when the preferred temperature is 81-140°C, the reaction time is 0.5-4 hours; when the preferred temperature is 141-180°C, the reaction time is 0.1 -0.5 hours.
  • the present invention has the following beneficial effects:
  • lignin's constituent units are mainly connected by carbon-oxygen bonds and carbon-carbon bonds. Lignin will undergo a condensation reaction during high temperature or acid-mediated extraction, resulting in the formation of new carbon-carbon bonds between lignin phenol units. This mechanism is consistent with the curing of most adhesives, such as phenolic resins and urea-formaldehyde resins. In a similar manner, a carbon-carbon bond cross-linked structure is formed during hot pressing. Therefore, the present invention found that by extracting uncondensed or low-condensed lignin from woody biomass, using it as an adhesive, and condensing and cross-linking it during the hot pressing process, the separated lignin can be directly used as wood. adhesive for this purpose.
  • the existing technology can use lignin to replace phenol and formaldehyde under alkaline conditions to synthesize lignin-phenol-formaldehyde resin adhesive
  • the technical route of the present invention has obvious differences with the existing technology of using lignin to synthesize adhesives. different.
  • the existing technology mainly utilizes the characteristic that lignin contains phenol structural units, and uses separated lignin (such as industrial sulfate lignin, sodium lignosulfonate, etc.) to replace part of phenol and formaldehyde and synthesize it under alkaline conditions.
  • Lignin-phenol-formaldehyde resin because the molecular weight of lignin is larger than that of phenol and there are fewer active sites on the aromatic ring, there are problems such as low lignin reactivity and high adhesive viscosity. Ultimately, the proportion of lignin replacing phenol is relatively high. Small, the synthesized adhesive has high viscosity and poor performance. However, the present invention can achieve faster extraction and condensation from woody biomass (such as wood, straw, etc.) by adding a modifier during the lignin extraction process.
  • woody biomass such as wood, straw, etc.
  • the existing technology requires the separated lignin to be further mixed with formaldehyde in an alkaline solution Polymerization is carried out under acidic conditions to obtain an adhesive, and the present invention directly extracts active lignin that can be used as an adhesive in one step under acidic conditions; thirdly, the present invention utilizes the extracted lignin to be insoluble under neutral or acidic conditions Due to the characteristics of water, solid lignin is precipitated by adding water to remove the remaining free modifiers (such as formaldehyde and acetone) in the reaction, avoiding the pollution problems caused by the release of free modifiers.
  • free modifiers such as formaldehyde and acetone
  • This adhesive is usually used in It is very important to meet pollution-free requirements in daily life scenes.
  • lignin is dissolved in an alkaline aqueous solution reaction system and cannot be separated and purified to remove free formaldehyde;
  • the purified lignin in the present invention Lignin can be transported in solid form and compounded when used, reducing transportation costs. and difficulty;
  • the lignin adhesive of the present invention is cured and cross-linked under the catalytic action of acidic conditions (such as its own acidic phenolic hydroxyl group or acid additives). By adjusting the amount of acid additives, the curing time It can be shortened to 1 minute, and the curing temperature can be reduced to about 100°C.
  • the synthesis and curing of traditional lignin phenolic resin are carried out under alkaline conditions.
  • the curing temperature usually needs to be higher than 150°C, and the curing time is as long as 15-30 minutes.
  • the present invention can directly use lignin as an adhesive.
  • lignin is used as an adhesive.
  • the main component while the lignin-phenol-formaldehyde resin synthesized using existing technology only contains part of lignin as a substitute for phenol.
  • the adhesive of the present invention greatly improves the economy of the existing pulping or biorefinery industry, reduces the dependence on traditional aldehyde-containing adhesives such as petroleum-based phenolic resin, urea-formaldehyde resin, and provides a new green Environmentally friendly adhesive.
  • traditional aldehyde-containing adhesives such as petroleum-based phenolic resin, urea-formaldehyde resin, and provides a new green Environmentally friendly adhesive.
  • the adhesive of the present invention can also achieve better curing and bonding effects at lower temperatures or shorter times. , can significantly reduce hot pressing energy consumption and improve production efficiency.
  • Extraction of lignin from woody biomass is mainly achieved by acid-catalyzed hydrolysis of lignin into low molecular weight lignin that is soluble in solvents; however, the dissolved lignin can be re-condensed under the catalysis of acid to form higher molecular weight lignin. Condensed lignin.
  • the condensation of lignin is inhibited by adding a modifier, and the sites in the lignin that are available for condensation and cross-linking are retained, so that when used as an adhesive, it can play a bonding role through condensation and cross-linking. .
  • the carbonyl group in the modifier can react with the meta-position of the phenolic hydroxyl group in the lignin unit to form a hydroxyalkyl group. This reaction inhibits the condensation of lignin itself by occupying or consuming the meta-position of the phenol unit. reaction, and the hydroxyalkyl group provides new active cross-linking sites for subsequent hot-pressure cross-linking of lignin.
  • Substances that have a carbonyl group and can meta-react with the phenolic hydroxyl group in the lignin unit under acidic conditions can play the role of inhibiting the condensation of lignin itself to obtain lignin with higher activity in the present invention, and can be used as Modifiers of the present invention include formaldehyde, parformaldehyde, paraformaldehyde, acetaldehyde, paraldehyde, paraacetaldehyde, propionaldehyde, butyraldehyde, furfural, benzaldehyde, acetone, butanone, etc.
  • adding an aldehyde or ketone with an equal molar amount to the phenol unit in lignin can completely occupy the active sites on the phenol unit of lignin, thereby inhibiting the condensation of lignin itself.
  • the phenol unit in the straw lignin (based on the average molecular weight of each phenol structural unit is 300g/mol) is about 0.5mmol, and the equivalent amount is required.
  • the amount of formaldehyde added can be less than the above estimated value; through experiments, it was found that the amount of formaldehyde added is about 0.3 of the mass of woody biomass. % of the wood separated As long as the quality can meet the requirements for more practical adhesive preparation, it is of course possible to add more formaldehyde.
  • the added mass of the modifier is 0.3%-200% of the mass of woody biomass.
  • the first solvent of the present invention is an excellent solvent for lignin.
  • Lignin contains both hydrophobic and hydrophilic groups, so it is necessary to prepare a suitable mixed solvent to achieve rapid dissolution of lignin.
  • the use of this type of solvent in the lignin extraction process is beneficial to dissolving the lignin in the woody biomass, allowing the lignin to react quickly with the modifier in the solvent.
  • the first solvent is a mixed solvent of an organic solvent and water, wherein the organic solvent includes 1,4-epoxybutane, 1,4-dioxane, 4-methylbutyrolactone, 2-methyltetrahydrofuran, and methanol , ethanol, propanol, formic acid, acetic acid, etc., accounting for 40%-95% of the total mass of the first solvent.
  • the organic solvent includes 1,4-epoxybutane, 1,4-dioxane, 4-methylbutyrolactone, 2-methyltetrahydrofuran, and methanol , ethanol, propanol, formic acid, acetic acid, etc., accounting for 40%-95% of the total mass of the first solvent.
  • the hot-pressure solidification of lignin with a small degree of condensation under acidic conditions is another point of invention that is different from the prior art. Due to the acidity of the phenolic hydroxyl groups of lignin itself, the adhesive prepared in the present invention can be cured and cross-linked by hot pressing without adding acid. That is, without adding acid as an additive, the actual curing and cross-linking still occurs under acidic conditions. Down. Adding an appropriate amount of acid can promote faster condensation and cross-linking of lignin, lower the hot-pressing temperature and shorten the hot-pressing time. This invention can significantly reduce hot-pressing energy consumption and improve production efficiency.
  • acids that can be used as auxiliaries include inorganic acids (such as sulfuric acid, hydrochloric acid, phosphoric acid) and organic acids (such as formic acid, oxalic acid, toluenesulfonic acid, terephthalic acid, lignin sulfonic acid).
  • thickeners and dispersants can also be added to the adhesive of the present invention.
  • the addition of thickener is beneficial to the uniform sizing of the adhesive.
  • Thickeners that can achieve this effect include carboxymethylcellulose, starch, flour, protein, etc.; the addition of dispersant can disperse solid lignin more evenly.
  • the dispersants that can achieve this effect are mainly surfactants, such as sodium dodecylbenzene sulfonate, sodium lignosulfonate, etc.
  • reaction solution (1) Add 90 grams of 1,4-dioxane and 10 grams of water (first solvent) into a 200 ml reaction kettle, adjust the pH to 0.4 (reaction pH value) with concentrated hydrochloric acid, and then add to the solution Add 5 grams of parformaldehyde (modifier) and 10 grams of eucalyptus wood powder (particle size: 80 mesh), stir and heat to 80 degrees Celsius to react for 4 hours (reaction conditions). After the reaction is completed, filter to obtain the reaction solution;
  • the bonding strength in different application environments was tested. It was determined that the bonding strength was 1.5Mpa according to the determination method of Class I plywood, and the bonding strength was measured according to the determination method of Class II plywood. The strength is 1.5Mpa. According to the measurement method of Class III plywood, the bonding strength is 1.8Mpa, both of which are greater than the national standard requirement of 0.7Mpa.
  • step (1) Except that the modifier in step (1) was replaced with 30 mg of paraformaldehyde, other steps were the same as in Example 1.
  • the solid dry weight obtained by separation in step (3) is about 1.4 grams. 1.4 grams of water (second solvent) was added to the solid to obtain a suspension as a glue.
  • Plywood was prepared according to the method of Example 1 and its strength was measured. According to the GB/T 9846-2015 "Ordinary Plywood" standard, the bonding strength in different application environments was tested. It was determined that the bonding strength was 0.8Mpa according to the determination method of Class I plywood, and the bonding strength was measured according to the determination method of Class II plywood. The strength is 0.9Mpa, and the bonding strength measured according to the Class III plywood measurement method is 1.0Mpa, both of which are greater than the national standard requirement of 0.7Mpa.
  • step (1) Except that the modifier in step (1) is replaced with 200 mg of paraldehyde, other steps are the same as in Example 1.
  • the solid dry weight obtained by separation in step (3) is about 1.4 grams. 1.4 grams of water (second solvent) was added to the solid to obtain a suspension as a glue.
  • Plywood was prepared according to the method of Example 1 and its strength was measured. According to the GB/T 9846-2015 "Ordinary Plywood" standard, the bonding strength in different application environments was tested. It was determined that the bonding strength was 1.2Mpa according to the determination method of Class I plywood, and the bonding strength was measured according to the determination method of Class II plywood. The strength is 1.3Mpa, and its gluing is measured according to the method of measuring type III plywood. The strength is 1.3Mpa, which is greater than the national standard requirement of 0.7Mpa.
  • step (1) Except that the modifier in step (1) is replaced with 1 gram of paracetaldehyde, other steps are the same as in Example 1.
  • Step (3) separates and obtains a solid dry weight of about 1.5 grams. 1.5 grams of water (second solvent) was added to the solid to obtain a suspension as a glue.
  • Plywood was prepared according to the method of Example 1 and its strength was measured. According to the GB/T 9846-2015 "Ordinary Plywood" standard, the bonding strength in different application environments was tested. It was determined that the bonding strength was 1.3Mpa according to the determination method of Class I plywood, and the bonding strength was measured according to the determination method of Class II plywood. The strength is 1.3Mpa. According to the measurement method of Class III plywood, the bonding strength is 1.5Mpa, both of which are greater than the national standard requirement of 0.7Mpa.
  • step (1) In addition to changing the reaction pH value in step (1) to 3 using sulfuric acid, the first solvent is changed to 40 grams of ethanol and 60 grams of water, the reaction conditions are changed to 180 degrees Celsius for 30 minutes, and the reaction solution in step (2) is concentrated to 4 After adding 20 grams of water, other steps are the same as in Example 1.
  • the solid dry weight obtained by separation in step (3) is about 1.2 grams. 1.5 grams of water (second solvent) was added to the solid to obtain a suspension as a glue.
  • Plywood was prepared according to the method of Example 1 and its strength was measured. According to the GB/T 9846-2015 "Ordinary Plywood" standard, the bonding strength in different application environments was tested. It was determined that the bonding strength was 0.8Mpa according to the determination method of Class I plywood, and the bonding strength was measured according to the determination method of Class II plywood. The strength is 0.8Mpa. According to the measurement method of Class III plywood, the bonding strength is 0.9Mpa, both of which are greater than the national standard requirement of 0.7Mpa.
  • step (1) Except that the reaction pH value in step (1) was adjusted to 3 using sulfuric acid, the first solvent was changed to 50 grams of acetone and 50 grams of water, and the reaction conditions were changed to 180 degrees Celsius for 30 minutes, other steps were the same as in Example 1.
  • the solid dry weight obtained by separation in step (3) is about 0.8 g. Add 0.8 grams of water (second solvent) to the solid to obtain a suspension that is a glue.
  • Plywood was prepared according to the method of Example 1 and its strength was measured. According to the GB/T 9846-2015 "Ordinary Plywood" standard, the bonding strength in different application environments was tested. It was determined that the bonding strength was 0.9Mpa according to the determination method of Class I plywood, and the bonding strength was measured according to the determination method of Class II plywood. The strength is 0.8Mpa. According to the measurement method of Class III plywood, the bonding strength is 1.1Mpa, both of which are greater than the national standard requirement of 0.7Mpa.
  • the first solvent is changed to 50 grams of acetic acid and 50 grams of water, the reaction conditions are changed to 180 degrees Celsius for 6 minutes, and the reaction solution in step (2) is adjusted to 100 degrees Celsius , remove all solvents under a pressure of 0.1 bar to a constant weight and then add 10 grams of water.
  • the other steps are the same as in Example 1.
  • the solid dry weight obtained by separation in step (3) is about 0.6 g. 0.6 g of water (second solvent) was added to the solid to obtain a suspension as a glue.
  • Plywood was prepared according to the method of Example 1 and its strength was measured. According to the GB/T 9846-2015 "Ordinary Plywood" standard, the bonding strength in different application environments was tested. It was determined that the bonding strength was 0.8Mpa according to the determination method of Class I plywood, and the bonding strength was measured according to the determination method of Class II plywood. The strength is 0.8Mpa. According to the measurement method of Class III plywood, the bonding strength is 1.0Mpa, both of which are greater than the national standard requirement of 0.7Mpa.
  • step (1) Except that the reaction pH value in step (1) was adjusted to 1 using hydrochloric acid, the reaction conditions were changed to 140 degrees Celsius for 20 minutes, and the modifier was replaced with 10 grams of paraacetaldehyde, the other steps were the same as in Example 1.
  • the solid dry weight obtained by separation in step (3) is about 1.4 grams. 2.8 grams of water (second solvent) was added to the solid to obtain a suspension as a glue.
  • Plywood was prepared according to the method of Example 1 and its strength was measured. According to the GB/T 9846-2015 "Ordinary Plywood" standard, the bonding strength in different application environments was tested. It was determined that the bonding strength was 1.6Mpa according to the determination method of Class I plywood, and the bonding strength was measured according to the determination method of Class II plywood. The strength is 1.5Mpa. According to the measurement method of Class III plywood, the bonding strength is 1.8Mpa, both of which are greater than the national standard requirement of 0.7Mpa.
  • step (1) Except that the reaction pH value in step (1) was adjusted to 0.6 using hydrochloric acid, the reaction conditions were changed to 100 degrees Celsius for 2 hours, and the modifier was replaced with 2 grams of benzaldehyde, the other steps were the same as in Example 1.
  • the solid dry weight obtained by separation in step (3) is about 1.3 grams. 2.6 grams of water (second solvent) was added to the solid to obtain a suspension as an adhesive.
  • Plywood was prepared according to the method of Example 1 and its strength was measured. According to the GB/T 9846-2015 "Ordinary Plywood" standard, the bonding strength in different application environments was tested. It was determined that the bonding strength was 1.4Mpa according to the determination method of Class I plywood, and the bonding strength was measured according to the determination method of Class II plywood. The strength is 1.5Mpa. According to the measurement method of Class III plywood, the bonding strength is 1.7Mpa, both of which are greater than the national standard requirement of 0.7Mpa.
  • reaction conditions are changed to 70 degrees Celsius for 10 hours, and except that the modifier was replaced with 20 grams of acetone, other steps were the same as in Example 1.
  • the solid dry weight obtained by separation in step (3) is about 1.6 grams. 3.2 grams of water (second solvent) was added to the solid to obtain a suspension as a glue.
  • Plywood was prepared according to the method of Example 1 and its strength was measured. According to the GB/T 9846-2015 "Ordinary Plywood" standard, the bonding strength in different application environments was tested. It was determined that the bonding strength was 1.7Mpa according to the determination method of Class I plywood, and the bonding strength was measured according to the determination method of Class II plywood. The strength is 1.6Mpa. According to the measurement method of Class III plywood, the bonding strength is 1.9Mpa, both of which are greater than the national standard requirement of 0.7Mpa.
  • Plywood was prepared according to the method of Example 1 and its strength was measured. According to the GB/T 9846-2015 "Ordinary Plywood" standard, the bonding strength in different application environments was tested. It was determined that the bonding strength was 1.5Mpa according to the determination method of Class I plywood, and the bonding strength was measured according to the determination method of Class II plywood. The strength is 1.5Mpa. According to the measurement method of Class III plywood, the bonding strength is 1.7Mpa, both of which are greater than the national standard requirement of 0.7Mpa.
  • Plywood was prepared according to the method of Example 1 and its strength was measured. According to the GB/T 9846-2015 "Ordinary Plywood" standard, the bonding strength in different application environments was tested. It was determined that the bonding strength was 1.5Mpa according to the determination method of Class I plywood, and the bonding strength was measured according to the determination method of Class II plywood. The strength is 1.6Mpa. According to the measurement method of Class III plywood, the bonding strength is 1.9Mpa, both of which are greater than the national standard requirement of 0.7Mpa.
  • step (4) Except that 3 grams of water (second solvent) in step (4) was replaced with 0.75 grams of 1,4-dioxane, other steps were the same as in Example 1.
  • Plywood was prepared according to the method of Example 1 and its strength was measured. According to the GB/T 9846-2015 "Ordinary Plywood" standard, the bonding strength in different application environments was tested. It was determined that the bonding strength was 1.8Mpa according to the determination method of Class I plywood, and the bonding strength was measured according to the determination method of Class II plywood. The strength is 1.7Mpa, and the bonding strength measured according to the Class III plywood measurement method is 2.0Mpa, both of which are greater than the national standard requirement of 0.7Mpa.
  • step (4) Except that 3 grams of water (second solvent) in step (4) is replaced by 30 grams of acetone, and the sizing amount on one side of the plywood is changed to 300g/ m2 , other steps are the same as in Example 1.
  • Plywood was prepared according to the method of Example 1 and its strength was measured. According to the GB/T 9846-2015 "Ordinary Plywood" standard, the bonding strength in different application environments was tested. It was determined that the bonding strength was 1.4Mpa according to the determination method of Class I plywood, and the bonding strength was measured according to the determination method of Class II plywood. The strength is 1.5Mpa. According to the measurement method of Class III plywood, the bonding strength is 1.6Mpa, both of which are greater than the national standard requirement of 0.7Mpa.
  • step (4) was changed to 220 degrees Celsius and the hot pressing time was changed to 2 minutes.
  • Plywood was prepared according to the method of Example 1 and its strength was measured. According to the GB/T 9846-2015 "Ordinary Plywood" standard, the bonding strength in different application environments was tested. It was determined that the bonding strength was 1.7Mpa according to the determination method of Class I plywood, and the bonding strength was measured according to the determination method of Class II plywood. The strength is 1.8Mpa. According to the measurement method of Class III plywood, the bonding strength is 1.9Mpa, both of which are greater than the national standard requirement of 0.7Mpa.
  • Plywood was prepared according to the method of Example 1 and its strength was measured. According to the GB/T 9846-2015 "Ordinary Plywood" standard, the bonding strength in different application environments was tested. It was determined that the bonding strength was 1.2Mpa according to the determination method of Class I plywood, and the bonding strength was measured according to the determination method of Class II plywood. The strength is 1.3Mpa. According to the measurement method of Class III plywood, the bonding strength is 1.5Mpa, both of which are greater than the national standard requirement of 0.7Mpa.
  • Plywood was prepared according to the method of Example 1 and its strength was measured. According to the GB/T 9846-2015 "Ordinary Plywood" standard, the bonding strength was tested in different application environments; it was determined that the bonding strength was 1.9Mpa according to the determination method of Class I plywood, and the bonding strength was measured according to the determination method of Class II plywood. The strength is 1.8Mpa. According to the measurement method of Class III plywood, the bonding strength is 1.9Mpa, both of which are greater than the national standard requirement of 0.7Mpa.
  • step (4) Except for adding 50 mg of sulfuric acid as a curing catalyst in step (4), changing the hot pressing temperature to 170 degrees Celsius, and changing the hot pressing time to 2 minutes, other steps were the same as in Example 1.
  • Plywood was prepared according to the method of Example 1 and its strength was measured. According to the GB/T 9846-2015 "Ordinary Plywood" standard, the bonding strength in different application environments was tested; it was determined that the bonding strength was 1.8 according to the Class I plywood measurement method. Mpa, the bonding strength measured according to the Class II plywood measurement method is 1.8Mpa, and the bonding strength measured according to the Class III plywood measurement method is 1.8Mpa, both are greater than the national standard requirement of 0.7Mpa.
  • step (4) Except for adding 50 mg of sulfuric acid as a curing catalyst in step (4), changing the hot pressing temperature to 140 degrees Celsius, and changing the hot pressing time to 7 minutes, other steps were the same as in Example 1.
  • Plywood was prepared according to the method of Example 1 and its strength was measured. According to the GB/T 9846-2015 "Ordinary Plywood" standard, the bonding strength in different application environments was tested. It was determined that the bonding strength was 1.4Mpa according to the determination method of Class I plywood, and the bonding strength was measured according to the determination method of Class II plywood. The strength is 1.3Mpa. According to the measurement method of Class III plywood, the bonding strength is 1.4Mpa, both of which are greater than the national standard requirement of 0.7Mpa.
  • step (4) Except for adding an additional 50 mg of sulfuric acid as a curing catalyst in step (4), changing the hot pressing temperature to 120 degrees Celsius, and changing the hot pressing time to 10 minutes, other steps were the same as in Example 1.
  • Plywood was prepared according to the method of Example 1 and its strength was measured. According to the GB/T 9846-2015 "Ordinary Plywood" standard, the bonding strength in different application environments was tested respectively; it was determined that the bonding strength was 1.1Mpa according to the determination method of Class I plywood, and the bonding strength was measured according to the determination method of Class II plywood. The strength is 1.0Mpa. According to the measurement method of Class III plywood, the bonding strength is 1.2Mpa, both of which are greater than the national standard requirement of 0.7Mpa.
  • step (4) Except for adding an additional 100 mg of sulfuric acid as a curing catalyst in step (4), changing the hot pressing temperature to 100 degrees Celsius, and changing the hot pressing time to 15 minutes, other steps were the same as in Example 1.
  • Plywood was prepared according to the method of Example 1 and its strength was measured. According to the GB/T 9846-2015 "Ordinary Plywood" standard, the bonding strength in different application environments was tested. It was determined that the bonding strength was 1.0Mpa according to the determination method of Class I plywood, and the bonding strength was measured according to the determination method of Class II plywood. The strength is 0.9Mpa. According to the measurement method of Class III plywood, the bonding strength is 0.9Mpa, both of which are greater than the national standard requirement of 0.7Mpa.
  • step (1) Except for replacing 90 grams of 1,4-dioxane and 10 grams of water (first solvent) in step (1) with 60 grams of 1,4-dioxane and 40 grams of water, other steps are the same as in Example 1 .
  • the solid dry weight obtained by separation in step (3) is about 0.9 g. 0.9 g of water (second solvent) was added to the solid to obtain a suspension as a glue.
  • Plywood was prepared according to the method of Example 1 and its strength was measured. According to the standard of GB/T 9846-2015 "Ordinary Plywood" Test the bonding strength under different application environments; after testing, the bonding strength measured according to the Class I plywood measurement method is 0.8Mpa, the bonding strength measured according to the Class II plywood measurement method is 0.9Mpa, and the bonding strength measured according to the Class III plywood measurement method is 0.9Mpa. The bonding strength is 1.0Mpa, which is greater than the national standard requirement of 0.7Mpa.
  • step (1) Except for replacing 90 grams of 1,4-dioxane and 10 grams of water (first solvent) in step (1) with 80 grams of 1,4-butylene oxide and 20 grams of water, other steps are the same as in Example 1 .
  • the solid dry weight obtained by separation in step (3) is about 1.1 g. 2.2 grams of water (second solvent) was added to the solid to obtain a suspension as a glue.
  • Plywood was prepared according to the method of Example 1 and its strength was measured. According to the GB/T 9846-2015 "Ordinary Plywood" standard, the bonding strength in different application environments was tested. It was determined that the bonding strength was 1.3Mpa according to the determination method of Class I plywood, and the bonding strength was measured according to the determination method of Class II plywood. The strength is 1.4Mpa. According to the measurement method of Class III plywood, the bonding strength is 1.5Mpa, both of which are greater than the national standard requirement of 0.7Mpa.
  • step (1) Except for replacing 90 grams of 1,4-dioxane and 10 grams of water (first solvent) in step (1) with 95 grams of 1,4-dioxane and 5 grams of water, other steps are the same as in Example 1 .
  • the solid dry weight obtained by separation in step (3) is about 1.3 grams. 2.6 grams of water (second solvent) was added to the solid to obtain a suspension as an adhesive.
  • Plywood was prepared according to the method of Example 1 and its strength was measured. According to the GB/T 9846-2015 "Ordinary Plywood" standard, the bonding strength in different application environments was tested. It was determined that the bonding strength was 1.3Mpa according to the determination method of Class I plywood, and the bonding strength was measured according to the determination method of Class II plywood. The strength is 1.3Mpa. According to the measurement method of Class III plywood, the bonding strength is 1.6Mpa, both of which are greater than the national standard requirement of 0.7Mpa.
  • step (1) Except that 10 grams of eucalyptus powder in step (1) is replaced with 33.3 grams of corn straw powder (particle size: 80 mesh), other steps are the same as in Example 1.
  • the solid dry weight obtained by separation in step (3) is about 3.9 grams. 7.8 grams of water (second solvent) was added to the solid to obtain a suspension as a glue.
  • Plywood was prepared according to the method of Example 1 and its strength was measured. According to the GB/T 9846-2015 "Ordinary Plywood" standard, the bonding strength in different application environments was tested. It was determined that the bonding strength was 1.6Mpa according to the determination method of Class I plywood, and the bonding strength was measured according to the determination method of Class II plywood. The strength is 1.7Mpa, and its gluing is measured according to the method of measuring type III plywood. The strength is 1.9Mpa, which is greater than the national standard requirement of 0.7Mpa.
  • step (1) Except for replacing 10 grams of eucalyptus wood powder with 5 grams of masson pine wood powder (particle size: 80 mesh) in step (1), other steps are the same as in Example 1.
  • the solid dry weight obtained by separation in step (3) is about 0.9 g. 1.8 grams of water (second solvent) was added to the solid to obtain a suspension as a glue.
  • Plywood was prepared according to the method of Example 1 and its strength was measured. According to the GB/T 9846-2015 "Ordinary Plywood" standard, the bonding strength in different application environments was tested. It was determined that the bonding strength was 1.4Mpa according to the determination method of Class I plywood, and the bonding strength was measured according to the determination method of Class II plywood. The strength is 1.5Mpa. According to the measurement method of Class III plywood, the bonding strength is 1.6Mpa, both of which are greater than the national standard requirement of 0.7Mpa.
  • the solid dry weight obtained by separation in step (3) is about 1.4 grams. 2.8 grams of water (second solvent) was added to the solid to obtain a suspension as a glue.
  • the lignin extracted under the same reaction conditions of 140 degrees Celsius and 20 minutes cannot be directly used as an adhesive.
  • Adding formaldehyde, acetaldehyde, acetone and other carbonyl group-containing modifiers and polymerization inhibitors during the extraction process in step (1) can inhibit the self-condensation of lignin during the extraction process and retain the cross-linkable active sites in the lignin.
  • the modifier can react with the phenol meta-site of lignin to form hydroxyalkyl groups, which improves the curing and cross-linking properties of lignin under acidic conditions.

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Abstract

一种从木质生物质中提取活性木质素并将木质素用作木材胶黏剂的方法，通过在木质素提取过程中加入改性剂，使得所提取的木质素在热压时具有自交联的性能以用作胶黏剂。在木质素改性后，再利用木质素不溶于水的特性，采用蒸馏、水析等步骤去除溶剂中剩余的改性剂，避免了木质素在交联过程中释放甲醛等游离改性剂。该方法可实现直接利用天然胶黏剂替代石油化工来源的胶黏剂，如酚醛树脂、脲醛树脂等，解决了生物炼制产业木质素难以高附加值利用的问题，能有效推动生物质化工产业的发展，并提供一种全新的绿色环保胶黏剂。

Description

从木质生物质提取木质素作为胶黏剂的方法 技术领域
本发明属于木质素高效利用技术领域，具体涉及一种从木质生物质提取活性木质素作为胶黏剂的方法，以及通过该方法获得的胶黏剂。
背景技术
化石资源短缺以及化石基产品所引发的环境问题已对人类社会的可持续发展产生了不可忽视的影响。将木质生物质解聚为化学品、燃料或相关可再生材料已成为缓解当前所面临能源和环境问题的有效途径之一。作为木质生物质的重要组成成分之一，木质素是地球上最丰富的芳香性天然高分子化合物。木质素作为一种天然的胶黏剂，在植物中起到将纤维素粘结在一起的作用，在提高植物刚度的同时，木质素中难降解的芳香环结构也有对抗外界病虫害入侵的作用。
木质素，又称木素，主要是由三种前体(对香豆醇，松柏醇和芥子醇)经酚羟基氧化自由基化、自由基离域以及自由基多级偶联等反应所形成的一类具有多种连接键的高分子化合物。根据自由基离域所产生的不同活性自由基位点，木质素单元间可形成C-O(如β–O–4、4–O–5等)和C–C(如5-5、β–5和β–β等)两大类连接键，木质素的合成途径、结构以及单元间连接键类型如下：
在制浆工业或生物炼制过程中，尽管反应介质中所使用的酸或碱可催化C-O键的断裂，提升木质生物质中木质素的溶出速率，但催化剂或者高温也同时促进木质素降解产物的重新缩合，使得木质素单元间交联产生新的C-C连接结构，这种分离出来的缩合木质素在高温下不能再次发生缩合交联。。
因此，现有技术主要是基于木质素单元含有苯酚结构，利用木质素替代苯酚在碱性条件下合成酚醛树脂胶黏剂并在碱性条件下热压固化，这些现有技术并没有涉及和利用木质素在酸性条件下可以自交联的特性来制作全木质素基胶黏剂。酚醛树脂胶黏剂的合成主要路径为苯酚与甲醛在碱性条件下形成预聚物，即胶黏剂，其反应主要涉及苯酚的羟甲基化和羟甲基与苯酚再缩合形成苯酚单元间的亚甲基桥连结构。在碱性条件下，羟甲基化主要发生在苯酚羟基的邻位和对位；而在木质素的苯酚单元中，酚羟基的对位已被烷基侧链占据，部分邻位也已被甲氧基占据。因此，木质素在替代苯酚合成酚醛树脂时，由于其活性位点少，合成的树脂胶黏性能差，当木质素添加比例超过30％左右时，所合成的胶黏剂性能急剧下降。此外，木质素的缩合造成木质素反应活性低，对合成的树脂性能影响主要体现在粘度大、所需热压固化温度明显升高(150-190摄氏度)以及所需时间变长(15-30分钟)、交联密度低等。此外，木质素-酚-醛树脂胶黏剂中含有大量未反应的游离甲醛，在作为胶黏剂使用后，往往释放出大量甲醛，造成甲醛超标等消费者重点关切的问题。因此，尽管近几十年来对木质素替代苯酚合成木质素-酚-醛树脂进行了研究，目前市场上未见有木质素-酚-醛胶黏剂的大规模生产和使用。
发明内容
为解决木质素合成酚醛树脂胶黏剂所存在的问题，本发明提供了一种从含木质素的木质生物质分离提取活性木质素用作木材胶黏剂的方法，尤其是将其直接用作木材胶黏剂的方法。本发明提取的活性木质素，可与溶剂、助剂复配后作为全木质素基胶黏剂施胶于木材表面，并通过热压使木质素自身发生缩合交联，从而将木材粘接在一起，此举将大大地提高现有制浆或生物炼制产业的经济性，减少对石油基来源的酚醛树脂、脲醛树脂等传统含醛胶黏剂的依赖，并提供一种全新的绿色环保胶黏剂。
为实现上述目的，本发明的技术方案是：
一种从木质生物质提取木质素作为胶黏剂的方法包括以下步骤：
(1)在pH值为0-3的条件下，将含木质素的木质生物质、改性剂以及第一溶剂混合，加热至70-180摄氏度反应，分离出所得反应液，所述改性剂为甲醛、三聚甲醛、多聚甲醛、 乙醛、三聚乙醛、多聚乙醛、丙醛、丁醛、苯甲醛、糠醛、丙酮、丁酮的一种或多种，加入质量为木质生物质质量的0.3％-200％；改性剂中的羰基基团可与木质素单元中酚羟基间位反应形成羟烷基基团，该反应通过占据或消耗苯酚单元间位位点起到抑制木质素在提取过程中发生自身缩合反应的作用，同时所形成的羟烷基基团为木质素后续热压交联提供了新的活性交联位点；
(2)将步骤(1)所得溶液加入水混合，得到悬浊液；
(3)分离步骤(2)悬浊液中的固体；
(4)将步骤(3)所得固体与第二溶剂混合，用作胶黏剂。
进一步地，将步骤(4)中胶黏剂均匀施于木材表面，在一定温度下热压固化交联。该全木质素基胶黏剂可直接应用在可通过热压实现固化粘合的领域而无需经过进一步反应或者添加其他有效成分，这些应用不限于制备胶合板、纤维板、刨花板、竹木复合板等；在实际应用时，热压温度可根据实际需求(例如板材厚度、水分等)进行调节。所述热压固化交联温度为100-220℃，优选地110-200℃，更优选地120-180℃，更优选地130-170℃。
进一步地，步骤(1)所述第一溶剂为有机溶剂和水的混合溶剂，其中有机溶剂为1,4-环氧丁烷、1,4-二氧己环、4-甲基丁内酯、2-甲基四氢呋喃、甲醇、乙醇、丙醇、丁醇、甲酸、乙酸、丙酮、丁酮的一种或多种，占第一溶剂总质量的40％-95％。将上述有机溶剂与水按比例混合得到第一溶剂，以此作为木质素的优良溶剂，在木质素提取过程中使用该溶剂有利于溶出木质生物质中的木质素，使木质素能与溶剂中的改性剂快速反应，从而抑制木质素的重新缩合。
进一步地，步骤(1)所述第一溶剂加入量为步骤(1)木质生物质质量的3-20倍，优选地4-15倍，更优选地5-10倍；该加入量针对间歇式反应釜，在实际应用过程中，如果采用连续蒸煮或者提取反应器，该添加量可根据需要进行调节。
进一步地，步骤(4)所述第二溶剂为水、甲醇、乙醇、丙酮、丁酮、1,4-环氧丁烷、2-甲基四氢呋喃、1,4-二氧己环的一种或多种，其作用主要在于将步骤(3)分离得到的固体形态的木质素分散均匀，便于将胶黏剂均匀施胶于需要粘合的木材表面。该溶剂的加入量为步骤(3)所述固体干重的0.5-10倍，优选为1-6倍，更优选为2-4倍。溶剂的加入量可调节后续胶黏剂施胶量；当加入较多溶剂配置得到低浓度胶黏剂时，可增大施胶量以达到较好胶黏效果，而当加入较少溶剂配置得到高浓度胶黏剂时，较少的施胶量即可达到较好效果。
进一步地，在步骤(4)中固体与第二溶剂混合后的物质中，还加入助剂，所述的助剂为酸、增稠剂、分散剂的一种或多种。
进一步地，在步骤(2)中加水混合前浓缩去除部分或者全部第一溶剂；浓缩去除溶剂，可减少加水量，有利于木质素析出成为固体悬浮物。
进一步地，步骤(1)的反应时间为0.1-10小时。当使用温度较高时，反应时间短。当优选温度为70-80℃时，反应时间为4-10小时；当优选温度为81-140℃时，反应时间为0.5-4小时；当优选温度为141-180℃时，反应时间为0.1-0.5小时。
与现有技术相比，本发明具有如下有益效果：
木质素作为一种天然高分子，各组成单元中主要以碳-氧键和碳-碳键连接起来。木质素在高温或者酸介导的提取过程中会发生缩合反应，导致木质素苯酚单元间形成新的碳-碳连接键，这一机理与大多数胶黏剂，例如酚醛树脂、脲醛树脂的固化方式类似，即在热压时形成碳-碳键交联结构。因此，本发明发现，从木质生物质提取未缩合或者缩合程度小的木质素，将其作为胶黏剂，在热压过程中使其缩合交联，即可实现利用分离的木质素直接作为木材胶黏剂这一目的。
尽管现有技术利用木质素替代苯酚在碱性条件下与甲醛能合成木质素-酚-醛树脂胶黏剂，但本发明的技术路线与现有技术利用木质素合成胶黏剂的思路具有明显不同。第一，现有技术主要利用木质素含有苯酚结构单元的特性，用已经分离出的木质素(例如工业硫酸盐木质素、木质素磺酸钠等)替代部分苯酚与甲醛在碱性条件下合成木质素-酚-醛树脂，但是由于木质素分子量比苯酚大、芳香环上的活性位点少，存在木质素反应活性低、胶黏剂粘度大等问题，最终导致木质素取代苯酚的比例较小，合成出的胶黏剂粘度大、性能差，而本发明是通过在木质素提取过程中加入改性剂，可以实现从木质生物质(例如木材、秸秆等)中较快的提取缩合程度小的木质素，并直接利用所提取的木质素作为全木质素基的胶黏剂，这与现有技术明显不同；第二，现有技术需要将分离出的木质素进一步与甲醛在碱性条件下进行聚合得到胶黏剂，而本发明是一步在酸性条件下直接提取出可用作胶黏剂的活性木质素；第三，本发明利用提取的木质素在中性或者酸性条件下不溶于水的特点，通过加入水析出固体木质素从而去除反应剩余的游离改性剂(例如甲醛、丙酮)，避免了游离改性剂释放所造成的污染问题，这对胶黏剂通常需要使用在生活场景中而必须达到无污染的要求至关重要，而现有技术中，木质素是溶解在碱性水溶液反应体系中，无法进行分离纯化去除游离的甲醛；第四，本发明中纯化后的木质素可以以固体形式运输，在使用时再进行复配，降低了运输成 本和难度；第五，本发明所述的木质素胶黏剂在酸性条件(例如自身酸性酚羟基或者酸助剂)的催化作用下进行固化交联，通过调节酸助剂加入量，固化时间可缩短至1分钟，固化温度可降低至100℃左右，而传统木质素酚醛树脂的合成和固化均在碱性条件下进行，固化温度通常需高于150℃，固化时间长达15-30分钟；第六，本发明可直接将木质素用作胶黏剂，除了加入水等作为溶剂外以及可加入或者不加入少量的增稠剂和分散剂便于施胶黏外，木质素为胶黏剂的主要成分，而采用现有技术合成的木质素-酚-醛树脂中只含有部分木质素作为苯酚的替代物。
本发明的胶黏剂大大地提高现有制浆或生物炼制产业的经济性，减少对石油基来源的酚醛树脂、脲醛树脂等传统含醛胶黏剂的依赖，并提供一种全新的绿色环保胶黏剂。此外，相对于其他类型胶黏剂，例如木质素-酚-醛树脂、酚醛树脂，本发明的胶黏剂还可以实现在较低的温度或者较短的时间下得到更好的固化粘合效果，可显著降低热压能耗，提高生产效率。
具体实施方式
从木质生物质提取木质素主要通过酸催化木质素水解为可溶解在溶剂中的低分子量木质素而实现；然而，溶出的木质素可在酸的催化作用下发生重新缩合，形成分子量较高的缩合木质素。在本发明中，通过加入改性剂来抑制木质素缩合，保留木质素中可供缩合交联的位点，从而实现其在作为胶黏剂时能通过缩合交联来起到粘合的作用。
本发明发现，改性剂中的羰基基团可与木质素单元中酚羟基间位反应，形成羟烷基基团，该反应通过占据或消耗苯酚单元间位位，起到抑制木质素自身缩合反应的作用，同时该羟烷基基团为木质素后续热压交联提供了新的活性交联位点。具有羰基基团，并在酸性条件下可与木质素单元中酚羟基间位反应的物质，均能够起到本发明中抑制木质素自身缩合以得到活性较高的木质素的作用，即可作为本发明的改性剂，包括甲醛、三聚甲醛、多聚甲醛、乙醛、三聚乙醛、多聚乙醛、丙醛、丁醛、糠醛、苯甲醛、丙酮、丁酮等。
就改性剂的理论添加量而言，添加与木质素中苯酚单元等摩尔量的醛或酮就能完全占据木质素苯酚单元上的活性位点，达到抑制木质素自身缩合的目的。以含15％木质素的1g秸秆，添加甲醛作为改性剂为例，该秸秆木质素中苯酚单元(以每个苯酚结构单元平均分子量为300g/mol计)约为0.5mmol,所需等当量的甲醛为0.5mmol×30mg/mmol＝15mg；因此，甲醛的添加量约为每克秸秆15毫克甲醛(即甲醛添加量约为秸秆质量的1.5％)。考虑到只需要抑制部分木质素缩合即能保留足够的可供固化交联的活性位点，甲醛的添加量可比前述估算值更少；通过实验发现，甲醛添加量约为木质生物质质量的0.3％时分离出的木 质素即能达到较实用的制备胶黏剂的要求，添加更多量的甲醛当然亦可。随着甲醛添加量的增加，所提取的木质素缩合程度逐渐降低，所制备的胶黏剂的强度逐渐增加；甲醛添加量增加至所提取的木质素基本未发生缩合后，制备的胶黏剂性能逐渐稳定在最佳的水平。优选改性剂的加入质量为木质生物质质量的0.3％-200％。
本发明的第一溶剂，是木质素的优良溶剂。木质素中既含有疏水基团也含有亲水基团，因此需要调配合适的混合溶剂以达到快速溶出木质素的效果。在木质素提取过程中使用该类溶剂有利于溶出木质生物质中的木质素，使木质素能与溶剂中的改性剂快速反应。该第一溶剂为有机溶剂和水的混合溶剂，其中有机溶剂包括1,4-环氧丁烷、1,4-二氧己环、4-甲基丁内酯、2-甲基四氢呋喃、甲醇、乙醇、丙醇、甲酸、乙酸等，占第一溶剂总质量的40％-95％。
将缩合程度小的木质素在酸性条件下热压固化，特别是在低温下热压固化是本发明不同于现有技术的另一个发明点。由于木质素自身酚羟基的酸性，本发明所制备的胶黏剂可在不加入酸时热压固化交联，即在不加入酸作为助剂的情况下，实际固化交联仍然发生在酸性条件下。加入适量的酸可促进木质素更快缩合交联，降低热压温度、减少热压时间，这一发明能显著降低热压能耗，提高生产效率，这是传统酚醛树脂和木质素-酚-醛树脂在碱性高温条件下固化所不具备的优势。因此，在实际应用中，可根据实际需求加入适量酸性助剂。在应用本发明的胶黏剂时，可以用作助剂的酸包括无机酸(例如硫酸、盐酸、磷酸)和有机酸(例如甲酸、草酸、甲基苯磺酸、对苯二甲酸、木质素磺酸)。
此外，本发明的胶黏剂也可加入增稠剂和分散剂。增稠剂的加入有利于胶黏剂的均匀施胶，能达到该效果的增稠剂包括羧甲基纤维素、淀粉、面粉、蛋白质等；分散剂的加入可将固体木质素更均匀地分散于水等溶剂中，能达到该效果的分散剂主要为表面活性剂，例如十二烷基苯磺酸钠、木质素磺酸钠等。
为了使本发明所述的内容更加便于理解，下面结合具体实施方式对本发明所述的技术方案做进一步的说明，但是本发明不仅限于此。
实施例1
(1)将90克1,4-二氧己环和10克水(第一溶剂)加入到200毫升反应釜中，用浓盐酸调节pH调至0.4(反应pH值)，然后向该溶液中加入5克三聚甲醛(改性剂)和10克桉木木粉(颗粒大小：80目)，搅拌并加热至80摄氏度反应4小时(反应条件)，反应结束后，过滤得到反应液；
(2)向该反应液加入400毫升水并搅拌得到悬浊液；
(3)过滤分离得到固体(干重约1.5克)；
(4)向该固体中加入3克水(第二溶剂)，得到悬浮液为胶黏剂。
木质素胶黏剂的性能评价：
按照GB/T 17657-2013《人造板及饰面人造板理化性能试验方法》中4.17小节规定制作胶合板并对胶合板强度进行测试。首先，选用速生杨木单板制备三层胶合板，单板水分含量为10％-12％，单板长度、宽度以及厚度分别为145mm、110mm和1.5mm。采用步骤(3)所制备的木质素胶黏剂对中间单板进行施胶，施胶方式为双面施胶，单面施胶量为100g/m2。然后，在施胶单板上下两侧分别粘附一张未施胶单板，使相邻单板的纤维方向互相垂直，将组合好的三层胶合板置于热压机加热板上，热压温度为190摄氏度，热压压力为1.5MPa，热压时间为7分钟。根据GB/T 9846-2015《普通胶合板》标准分别测试不同应用环境下的胶合强度；经测定，按Ⅰ类胶合板测定方法测得其胶合强度为1.5Mpa，按Ⅱ类胶合板测定方法测得其胶合强度为1.5Mpa，按Ⅲ类胶合板测定方法测得其胶合强度为1.8Mpa，均大于0.7Mpa的国家标准要求。
实施例2
除将步骤(1)中的改性剂替换为30毫克多聚甲醛外，其它步骤与实施例1相同。
步骤(3)分离得到固体干重约1.4克。向该固体中加入1.4克水(第二溶剂)，得到悬浮液为胶黏剂。
按实施例1方法制备胶合板并测定其强度。根据GB/T 9846-2015《普通胶合板》标准分别测试不同应用环境下的胶合强度；经测定，按Ⅰ类胶合板测定方法测得其胶合强度为0.8Mpa，按Ⅱ类胶合板测定方法测得其胶合强度为0.9Mpa，按Ⅲ类胶合板测定方法测得其胶合强度为1.0Mpa，均大于0.7Mpa的国家标准要求。
实施例3
除将步骤(1)中的改性剂替换为200毫克三聚乙醛外，其它步骤与实施例1相同。
步骤(3)分离得到固体干重约1.4克。向该固体中加入1.4克水(第二溶剂)，得到悬浮液为胶黏剂。
按实施例1方法制备胶合板并测定其强度。根据GB/T 9846-2015《普通胶合板》标准分别测试不同应用环境下的胶合强度；经测定，按Ⅰ类胶合板测定方法测得其胶合强度为1.2Mpa，按Ⅱ类胶合板测定方法测得其胶合强度为1.3Mpa，按Ⅲ类胶合板测定方法测得其胶合 强度为1.3Mpa，均大于0.7Mpa的国家标准要求。
实施例4
除将步骤(1)中的改性剂替换为1克多聚乙醛外，其它步骤与实施例1相同。
步骤(3)分离得到固体干重约1.5克。向该固体中加入1.5克水(第二溶剂)，得到悬浮液为胶黏剂。
按实施例1方法制备胶合板并测定其强度。根据GB/T 9846-2015《普通胶合板》标准分别测试不同应用环境下的胶合强度；经测定，按Ⅰ类胶合板测定方法测得其胶合强度为1.3Mpa，按Ⅱ类胶合板测定方法测得其胶合强度为1.3Mpa，按Ⅲ类胶合板测定方法测得其胶合强度为1.5Mpa，均大于0.7Mpa的国家标准要求。
实施例5
除将步骤(1)中反应pH值变为利用硫酸调至3、第一溶剂变为40克乙醇和60克水、反应条件变为180摄氏度30分钟，以及步骤(2)反应液浓缩至4克后再加入20克水外，其它步骤与实施例1相同。
步骤(3)分离得到固体干重约1.2克。向该固体中加入1.5克水(第二溶剂)，得到悬浮液为胶黏剂。
按实施例1方法制备胶合板并测定其强度。根据GB/T 9846-2015《普通胶合板》标准分别测试不同应用环境下的胶合强度；经测定，按Ⅰ类胶合板测定方法测得其胶合强度为0.8Mpa，按Ⅱ类胶合板测定方法测得其胶合强度为0.8Mpa，按Ⅲ类胶合板测定方法测得其胶合强度为0.9Mpa，均大于0.7Mpa的国家标准要求。
实施例6
除将步骤(1)中反应pH值变为利用硫酸调至3、第一溶剂变为50克丙酮和50克水、以及反应条件变为180摄氏度30分钟外，其它步骤与实施例1相同。
步骤(3)分离得到固体干重约0.8克。向该固体中加入0.8克水(第二溶剂)，得到悬浮液为胶黏剂。
按实施例1方法制备胶合板并测定其强度。根据GB/T 9846-2015《普通胶合板》标准分别测试不同应用环境下的胶合强度；经测定，按Ⅰ类胶合板测定方法测得其胶合强度为0.9Mpa，按Ⅱ类胶合板测定方法测得其胶合强度为0.8Mpa，按Ⅲ类胶合板测定方法测得其胶合强度为1.1Mpa，均大于0.7Mpa的国家标准要求。
实施例7
除将步骤(1)中反应pH值变为利用硫酸调至2、第一溶剂变为50克乙酸和50克水、反应条件变为180摄氏度6分钟，以及步骤(2)反应液在100摄氏度、0.1bar压力下去除所有溶剂至恒重后加入10克水外，其它步骤与实施例1相同。
步骤(3)分离得到固体干重约0.6克。向该固体中加入0.6克水(第二溶剂)，得到悬浮液为胶黏剂。
按实施例1方法制备胶合板并测定其强度。根据GB/T 9846-2015《普通胶合板》标准分别测试不同应用环境下的胶合强度；经测定，按Ⅰ类胶合板测定方法测得其胶合强度为0.8Mpa，按Ⅱ类胶合板测定方法测得其胶合强度为0.8Mpa，按Ⅲ类胶合板测定方法测得其胶合强度为1.0Mpa，均大于0.7Mpa的国家标准要求。
实施例8
除将步骤(1)中反应pH值变为利用盐酸调至1、反应条件变为140摄氏度20分钟，以及将改性剂替换为10克多聚乙醛外，其它步骤与实施例1相同。
步骤(3)分离得到固体干重约1.4克。向该固体中加入2.8克水(第二溶剂)，得到悬浮液为胶黏剂。
按实施例1方法制备胶合板并测定其强度。根据GB/T 9846-2015《普通胶合板》标准分别测试不同应用环境下的胶合强度；经测定，按Ⅰ类胶合板测定方法测得其胶合强度为1.6Mpa，按Ⅱ类胶合板测定方法测得其胶合强度为1.5Mpa，按Ⅲ类胶合板测定方法测得其胶合强度为1.8Mpa，均大于0.7Mpa的国家标准要求。
实施例9
除将步骤(1)中反应pH值变为利用盐酸调至0.6、反应条件变为100摄氏度2小时、以及改性剂替换为2克苯甲醛外，其它步骤与实施例1相同。
步骤(3)分离得到固体干重约1.3克。向该固体中加入2.6克水(第二溶剂)，得到悬浮液为胶黏剂。
按实施例1方法制备胶合板并测定其强度。根据GB/T 9846-2015《普通胶合板》标准分别测试不同应用环境下的胶合强度；经测定，按Ⅰ类胶合板测定方法测得其胶合强度为1.4Mpa，按Ⅱ类胶合板测定方法测得其胶合强度为1.5Mpa，按Ⅲ类胶合板测定方法测得其胶合强度为1.7Mpa，均大于0.7Mpa的国家标准要求。
实施例10
除将步骤(1)中反应pH值变为利用盐酸调至0、反应条件变为70摄氏度10小时、以 及将改性剂替换为20克丙酮外，其它步骤与实施例1相同。
步骤(3)分离得到固体干重约1.6克。向该固体中加入3.2克水(第二溶剂)，得到悬浮液为胶黏剂。
按实施例1方法制备胶合板并测定其强度。根据GB/T 9846-2015《普通胶合板》标准分别测试不同应用环境下的胶合强度；经测定，按Ⅰ类胶合板测定方法测得其胶合强度为1.7Mpa，按Ⅱ类胶合板测定方法测得其胶合强度为1.6Mpa，按Ⅲ类胶合板测定方法测得其胶合强度为1.9Mpa，均大于0.7Mpa的国家标准要求。
实施例11
除在步骤(4)额外加入10毫克羧甲基纤维素作为增稠剂外，其它步骤与实施例1相同。
按实施例1方法制备胶合板并测定其强度。根据GB/T 9846-2015《普通胶合板》标准分别测试不同应用环境下的胶合强度；经测定，按Ⅰ类胶合板测定方法测得其胶合强度为1.5Mpa，按Ⅱ类胶合板测定方法测得其胶合强度为1.5Mpa，按Ⅲ类胶合板测定方法测得其胶合强度为1.7Mpa，均大于0.7Mpa的国家标准要求。
实施例12
除在步骤(4)额外加入20毫克木质素磺酸钠作为分散剂外，其它步骤与实施例1相同。
按实施例1方法制备胶合板并测定其强度。根据GB/T 9846-2015《普通胶合板》标准分别测试不同应用环境下的胶合强度；经测定，按Ⅰ类胶合板测定方法测得其胶合强度为1.5Mpa，按Ⅱ类胶合板测定方法测得其胶合强度为1.6Mpa，按Ⅲ类胶合板测定方法测得其胶合强度为1.9Mpa，均大于0.7Mpa的国家标准要求。
实施例13
除将步骤(4)的3克水(第二溶剂)替换为0.75克1,4-二氧己环外，其它步骤与实施例1相同。
按实施例1方法制备胶合板并测定其强度。根据GB/T 9846-2015《普通胶合板》标准分别测试不同应用环境下的胶合强度；经测定，按Ⅰ类胶合板测定方法测得其胶合强度为1.8Mpa，按Ⅱ类胶合板测定方法测得其胶合强度为1.7Mpa，按Ⅲ类胶合板测定方法测得其胶合强度为2.0Mpa，均大于0.7Mpa的国家标准要求。
实施例14
除将步骤(4)的3克水(第二溶剂)替换为30克丙酮，以及胶合板单面施胶量变为300g/m2外，其它步骤与实施例1相同。
按实施例1方法制备胶合板并测定其强度。根据GB/T 9846-2015《普通胶合板》标准分别测试不同应用环境下的胶合强度；经测定，按Ⅰ类胶合板测定方法测得其胶合强度为1.4Mpa，按Ⅱ类胶合板测定方法测得其胶合强度为1.5Mpa，按Ⅲ类胶合板测定方法测得其胶合强度为1.6Mpa，均大于0.7Mpa的国家标准要求。
实施例15
除将步骤(4)的热压温度变为220摄氏度，热压时间变为2分钟外，其它步骤与实施例1相同。
按实施例1方法制备胶合板并测定其强度。根据GB/T 9846-2015《普通胶合板》标准分别测试不同应用环境下的胶合强度；经测定，按Ⅰ类胶合板测定方法测得其胶合强度为1.7Mpa，按Ⅱ类胶合板测定方法测得其胶合强度为1.8Mpa，按Ⅲ类胶合板测定方法测得其胶合强度为1.9Mpa，均大于0.7Mpa的国家标准要求。
实施例16
除将热压温度变为150摄氏度、热压时间变为8分钟外，其它步骤与实施例1相同。
按实施例1方法制备胶合板并测定其强度。根据GB/T 9846-2015《普通胶合板》标准分别测试不同应用环境下的胶合强度；经测定，按Ⅰ类胶合板测定方法测得其胶合强度为1.2Mpa，按Ⅱ类胶合板测定方法测得其胶合强度为1.3Mpa，按Ⅲ类胶合板测定方法测得其胶合强度为1.5Mpa，均大于0.7Mpa的国家标准要求。
实施例17
除在步骤(4)额外加入50毫克硫酸作为固化催化剂，以及热压时间变为1分钟外，其它步骤与实施例1相同。
按实施例1方法制备胶合板并测定其强度。根据GB/T 9846-2015《普通胶合板》标准分别测试不同应用环境下的胶合强度；经测定，按Ⅰ类胶合板测定方法测得其胶合强度为1.9Mpa，按Ⅱ类胶合板测定方法测得其胶合强度为1.8Mpa，按Ⅲ类胶合板测定方法测得其胶合强度为1.9Mpa，均大于0.7Mpa的国家标准要求。
实施例18
除在步骤(4)额外加入50毫克硫酸作为固化催化剂，以及将热压温度变为170摄氏度、热压时间变为2分钟外，其它步骤与实施例1相同。
按实施例1方法制备胶合板并测定其强度。根据GB/T 9846-2015《普通胶合板》标准分别测试不同应用环境下的胶合强度；经测定，按Ⅰ类胶合板测定方法测得其胶合强度为1.8 Mpa，按Ⅱ类胶合板测定方法测得其胶合强度为1.8Mpa，按Ⅲ类胶合板测定方法测得其胶合强度为1.8Mpa，均大于0.7Mpa的国家标准要求。
实施例19
除在步骤(4)额外加入50毫克硫酸作为固化催化剂，以及将热压温度变为140摄氏度、热压时间变为7分钟外，其它步骤与实施例1相同。
按实施例1方法制备胶合板并测定其强度。根据GB/T 9846-2015《普通胶合板》标准分别测试不同应用环境下的胶合强度；经测定，按Ⅰ类胶合板测定方法测得其胶合强度为1.4Mpa，按Ⅱ类胶合板测定方法测得其胶合强度为1.3Mpa，按Ⅲ类胶合板测定方法测得其胶合强度为1.4Mpa，均大于0.7Mpa的国家标准要求。
实施例20
除在步骤(4)额外加入50毫克硫酸作为固化催化剂，以及将热压温度变为120摄氏度、热压时间变为10分钟外，其它步骤与实施例1相同。
按实施例1方法制备胶合板并测定其强度。根据GB/T 9846-2015《普通胶合板》标准分别测试不同应用环境下的胶合强度；经测定，按Ⅰ类胶合板测定方法测得其胶合强度为1.1Mpa，按Ⅱ类胶合板测定方法测得其胶合强度为1.0Mpa，按Ⅲ类胶合板测定方法测得其胶合强度为1.2Mpa，均大于0.7Mpa的国家标准要求。
实施例21
除在步骤(4)额外加入100毫克硫酸作为固化催化剂，以及将热压温度变为100摄氏度、热压时间变为15分钟外，其它步骤与实施例1相同。
按实施例1方法制备胶合板并测定其强度。根据GB/T 9846-2015《普通胶合板》标准分别测试不同应用环境下的胶合强度；经测定，按Ⅰ类胶合板测定方法测得其胶合强度为1.0Mpa，按Ⅱ类胶合板测定方法测得其胶合强度为0.9Mpa，按Ⅲ类胶合板测定方法测得其胶合强度为0.9Mpa，均大于0.7Mpa的国家标准要求。
实施例22
除将步骤(1)90克1,4-二氧己环和10克水(第一溶剂)替换为60克1,4-二氧己环和40克水外，其它步骤与实施例1相同。
步骤(3)分离得到固体干重约0.9克。向该固体中加入0.9克水(第二溶剂)，得到悬浮液为胶黏剂。
按实施例1方法制备胶合板并测定其强度。根据GB/T 9846-2015《普通胶合板》标准分 别测试不同应用环境下的胶合强度；经测定，按Ⅰ类胶合板测定方法测得其胶合强度为0.8Mpa，按Ⅱ类胶合板测定方法测得其胶合强度为0.9Mpa，按Ⅲ类胶合板测定方法测得其胶合强度为1.0Mpa，均大于0.7Mpa的国家标准要求。
实施例23
除将步骤(1)90克1,4-二氧己环和10克水(第一溶剂)替换为80克1,4-环氧丁烷和20克水外，其它步骤与实施例1相同。
步骤(3)分离得到固体干重约1.1克。向该固体中加入2.2克水(第二溶剂)，得到悬浮液为胶黏剂。
按实施例1方法制备胶合板并测定其强度。根据GB/T 9846-2015《普通胶合板》标准分别测试不同应用环境下的胶合强度；经测定，按Ⅰ类胶合板测定方法测得其胶合强度为1.3Mpa，按Ⅱ类胶合板测定方法测得其胶合强度为1.4Mpa，按Ⅲ类胶合板测定方法测得其胶合强度为1.5Mpa，均大于0.7Mpa的国家标准要求。
实施例24
除将步骤(1)90克1,4-二氧己环和10克水(第一溶剂)替换为95克1,4-二氧己环和5克水外，其它步骤与实施例1相同。
步骤(3)分离得到固体干重约1.3克。向该固体中加入2.6克水(第二溶剂)，得到悬浮液为胶黏剂。
按实施例1方法制备胶合板并测定其强度。根据GB/T 9846-2015《普通胶合板》标准分别测试不同应用环境下的胶合强度；经测定，按Ⅰ类胶合板测定方法测得其胶合强度为1.3Mpa，按Ⅱ类胶合板测定方法测得其胶合强度为1.3Mpa，按Ⅲ类胶合板测定方法测得其胶合强度为1.6Mpa，均大于0.7Mpa的国家标准要求。
实施例25
除将步骤(1)中10克桉木粉替换为33.3克玉米秸秆粉(颗粒大小：80目)外，其它步骤与实施例1相同。
步骤(3)分离得到固体干重约3.9克。向该固体中加入7.8克水(第二溶剂)，得到悬浮液为胶黏剂。
按实施例1方法制备胶合板并测定其强度。根据GB/T 9846-2015《普通胶合板》标准分别测试不同应用环境下的胶合强度；经测定，按Ⅰ类胶合板测定方法测得其胶合强度为1.6Mpa，按Ⅱ类胶合板测定方法测得其胶合强度为1.7Mpa，按Ⅲ类胶合板测定方法测得其胶合 强度为1.9Mpa，均大于0.7Mpa的国家标准要求。
实施例26
除将步骤(1)中10克桉木粉替换为5克马尾松木粉(颗粒大小：80目)外，其它步骤与实施例1相同。
步骤(3)分离得到固体干重约0.9克。向该固体中加入1.8克水(第二溶剂)，得到悬浮液为胶黏剂。
按实施例1方法制备胶合板并测定其强度。根据GB/T 9846-2015《普通胶合板》标准分别测试不同应用环境下的胶合强度；经测定，按Ⅰ类胶合板测定方法测得其胶合强度为1.4Mpa，按Ⅱ类胶合板测定方法测得其胶合强度为1.5Mpa，按Ⅲ类胶合板测定方法测得其胶合强度为1.6Mpa，均大于0.7Mpa的国家标准要求。
对比例1
除步骤(1)中不加入10克多聚乙醛作为改性剂外，其它步骤与实施例8相同。
步骤(3)分离得到固体干重约1.4克。向该固体中加入2.8克水(第二溶剂)，得到悬浮液为胶黏剂。
经施胶热压后发现，胶合板没有粘合，三层胶合板的胶合强度为0Mpa。
从以上对比例1中可以看出，在不添加醛类等改性剂时，在同等的140摄氏度20分钟反应条件下提取的木质素无法直接用作胶黏剂。在步骤(1)提取过程中加入甲醛、乙醛、丙酮等含羰基基团的改性剂和阻聚剂可以抑制木质素在提取过程中的自身缩合，保留木质素中可交联的活性位点；同时，改性剂可与木质素苯酚间位位点反应形成羟烷基基团，提高木质素在酸性条件下的固化交联特性。
以上实施例的说明和解释，能使本领域技术人员理解和实现本发明。但本发明将不会被限制于上述这些实施例，本文中所公开的发明原理可以在不脱离本发明的精神或范围的情况下，在其它实施例中实现，而这些实施例的修改对本领域技术人员来说应是显而易见的，仍将在本专利的保护范围之内。

Claims (10)

  1. 一种从木质生物质提取木质素作为胶黏剂的方法，其特征在于：包括以下步骤：
    (1)在pH值为0-3的条件下，将含木质素的木质生物质、改性剂以及第一溶剂混合，加热至70-180℃反应，并分离出所得反应液，所述改性剂为甲醛、三聚甲醛、多聚甲醛、乙醛、三聚乙醛、多聚乙醛、丙醛、丁醛、苯甲醛、糠醛、丙酮、丁酮的一种或多种，加入质量为木质生物质质量的0.3％-200％；
    (2)向步骤(1)分离出的反应液中加入水混合，得到悬浊液；
    (3)分离步骤(2)悬浊液中的固体；
    (4)将步骤(3)所得固体与第二溶剂混合，用作胶黏剂。
  2. 根据权利要求1所述的从木质生物质提取木质素作为胶黏剂的方法，其特征在于：步骤(1)所述第一溶剂为有机溶剂和水的混合溶剂，其中有机溶剂为1,4-环氧丁烷、1,4-二氧己环、4-甲基丁内酯、2-甲基四氢呋喃、甲醇、乙醇、丙醇、丁醇、甲酸、乙酸、丙酮、丁酮的一种或多种，占第一溶剂总质量的40％-95％。
  3. 根据权利要求2所述的从木质生物质提取木质素作为胶黏剂的方法，其特征在于：步骤(1)中第一溶剂加入量为木质生物质质量的3-20倍。
  4. 根据权利要求1所述的从木质生物质提取木质素作为胶黏剂的方法，其特征在于：所述第二溶剂为水、甲醇、乙醇、丙酮、丁酮、1,4-环氧丁烷、、2-甲基四氢呋喃、1,4-二氧己环的一种或多种。
  5. 根据权利要求4所述的从木质生物质提取木质素作为胶黏剂的方法，其特征在于：所述第二溶剂的加入量为步骤(3)所述固体干重的0.5-10倍。
  6. 根据权利要求1所述的从木质生物质提取木质素作为胶黏剂的方法，其特征在于：步骤(4)得到的固体与第二溶剂混合后的物质中还加入助剂，所述助剂为酸、增稠剂、分散剂的一种或多种。
  7. 根据权利要求1所述的从木质生物质提取木质素作为胶黏剂的方法，其特征在于：步骤(2)中加水混合前浓缩去除部分或全部第一溶剂。
  8. 根据权利要求1所述的从木质生物质提取木质素作为胶黏剂的方法，其特征在于：步骤(1)中反应的时间为0.1-10小时。
  9. 一种如权利要求1-8任一项所述的方法制得的胶黏剂。
  10. 一种如权利要求9所述的胶黏剂的应用，其特征在于：直接将胶黏剂施于木材表面，在100-220摄氏度下热压交联，起到粘结木材的作用。
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CN114736652A (zh) * 2022-04-28 2022-07-12 福建农林大学 一种从木质生物质提取木质素作为胶黏剂的方法
CN115746784A (zh) * 2022-10-28 2023-03-07 山东百木生新材料科技有限公司 一种全木质素基胶黏剂的制备方法

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