阅读说明：本技术 植物糖基聚酯类胶黏剂及其制备方法和应用 (Plant glycosyl polyester adhesive as well as preparation method and application thereof ) 是由 李善明 邢雪峰 傅峰 陈志林 林兰英 彭立民 于 2020-12-30 设计创作，主要内容包括：本发明涉及一种植物糖基聚酯类胶黏剂及其制备方法和应用,属于木材加工领域。该胶黏剂包括麦芽糖糊精、葡萄糖和/或环糊精,草酸、琥珀酸和/或聚马来酸酐,水,催化剂,固化剂,偶联剂,改性剂,防水剂和填料；由麦芽糖糊精、葡萄糖和/或环糊精与草酸、琥珀酸和/或聚马来酸酐发生聚酯反应聚合而成。本发明还公开了该胶黏剂的制备方法和应用。本发明制备的植物糖基聚酯类胶黏剂具有致密的三维网络结构,胶合强度高,耐水性好、性能稳定。利用该木材胶黏剂制备的无醛改性木和无醛人造板,成本低廉、绿色环保,具有良好的环境效益和经济效益。(The invention relates to a plant glycosyl polyester adhesive as well as a preparation method and application thereof, belonging to the field of wood processing. The adhesive comprises maltodextrin, glucose and/or cyclodextrin, oxalic acid, succinic acid and/or polymaleic anhydride, water, a catalyst, a curing agent, a coupling agent, a modifier, a waterproof agent and a filler; is prepared from maltodextrin, glucose and/or cyclodextrin and oxalic acid, succinic acid and/or polymaleic anhydride through polyester reaction. The invention also discloses a preparation method and application of the adhesive. The plant glycosyl polyester adhesive prepared by the invention has a compact three-dimensional network structure, high bonding strength, good water resistance and stable performance. The aldehyde-free modified wood and aldehyde-free artificial board prepared by the wood adhesive has low cost, is green and environment-friendly, and has good environmental benefit and economic benefit.)

1. A kind of vegetable sugar base polyester adhesive, characterized by that: the adhesive comprises the following raw materials in parts by weight:

maltodextrin, glucose and/or cyclodextrin: 20-200 parts of a solvent;

oxalic acid, succinic acid and/or polymaleic anhydride: 40-300 parts;

water: 200-600 parts;

catalyst: 2-8 parts;

curing agent: 5-20 parts of a solvent;

coupling agent: 0-10 parts;

modifying agent: 0-80 parts;

water-proofing agent: 1-5 parts;

filling: 0-500 parts;

is prepared from maltodextrin, glucose and/or cyclodextrin and oxalic acid, succinic acid and/or polymaleic anhydride through polyester reaction.

2. The plant sugar based polyester based adhesive according to claim 1, wherein: the catalyst is benzene sulfonic acid, p-methyl benzene sulfonic acid, sodium dodecyl sulfate or sulfuric acid; the curing agent is a water-based isocyanate curing agent, water-based epoxy resin or polyimide; the coupling agent is a silane coupling agent, a titanate coupling agent or an aluminate coupling agent; the modifier is a preservative, an antibacterial agent, a flame retardant, an antistatic agent, an antioxidant, a coloring agent and/or an ultraviolet protective agent; the waterproof agent is methyl potassium silicate, methyl sodium silicate and/or a fluorine silicon material; the filler is industrial starch, montmorillonite or calcium carbonate.

3. A preparation method of a plant glycosyl polyester adhesive comprises the following steps:

1) preparing a raw material formulation according to claim 1 or 2;

2) putting maltodextrin, glucose and/or cyclodextrin, part of oxalic acid, succinic acid and/or polymaleic anhydride, a catalyst and water into a reaction tank, stirring at room temperature, uniformly blending, then adding the rest oxalic acid, succinic acid and/or polymaleic anhydride, a curing agent, a coupling agent, a modifying agent, a waterproof agent and a filler, and uniformly mixing to prepare the low-viscosity reactive polyester adhesive;

or putting maltodextrin, glucose and/or cyclodextrin, oxalic acid, succinic acid and/or polymaleic anhydride, a catalyst and water into a reaction tank, stirring at room temperature, uniformly blending, then adding a curing agent, a coupling agent, a modifying agent, a waterproof agent and a filler, and uniformly mixing to prepare the low-viscosity reactive polyester adhesive;

or adding part of oxalic acid, succinic acid and/or polymaleic anhydride, a catalyst and water into maltodextrin, glucose and/or cyclodextrin, stirring at room temperature, uniformly mixing, heating to 100-180 ℃, and keeping the temperature for 0.5-5 h; and adding the rest oxalic acid, succinic acid and/or polymaleic anhydride, curing agent, coupling agent, modifier and waterproof agent, uniformly mixing, heating again, cooling, and adding filler to prepare the viscous polyester adhesive.

4. The method for preparing the vegetable sugar-based polyester adhesive according to claim 3, wherein the method comprises the following steps: in the polyester reaction, the molar ratio of carboxyl groups in oxalic acid, succinic acid and/or polymaleic anhydride to hydroxyl groups in maltodextrin, glucose and/or cyclodextrin is from 1:5 to 20: 1.

5. The method for preparing the vegetable sugar-based polyester adhesive according to claim 3, wherein the method comprises the following steps: the temperature of reheating treatment after uniform mixing is 100-180 ℃, and the heat preservation time is 2-5 h.

6. The application of the plant sugar based polyester adhesive in wood impregnation or bonding according to claim 1 or 2, wherein the polyester adhesive enters the interior of the wood through an impregnation process, and then is chemically reacted through hot pressing, microwaves, high-energy radiation, ultraviolet irradiation or any combination thereof to perform gluing; the polyester adhesive is coated on the surface of a wood veneer through roller coating, and is subjected to chemical reaction through hot pressing, microwave, high-energy radiation, ultraviolet irradiation or any combination of the hot pressing, the microwave, the high-energy radiation and the ultraviolet radiation to be adhered to form a plywood; the polyester adhesive is mixed with wood fiber or wood shavings, and is adhered through hot pressing to form a fiber board or a shaving board.

7. A preparation method of aldehyde-free modified wood comprises the following steps: the plant glycosyl polyester adhesive as claimed in claim 1 or 2 is used for impregnating the artificial fast-growing forest solid wood or the microwave expanded wood, and the impregnated wood is cured at 100-140 ℃.

8. The method for producing aldehyde-free modified wood according to claim 7, wherein: the curing method of the impregnated wood comprises the following steps: putting the impregnated wood into an oven at 100-140 ℃ and curing for 10-24 h; or putting the impregnated wood into a hot press, hot-pressing for 15min-2h at the temperature of 100-140 ℃, taking out, putting into a drying kiln, and drying and shaping.

9. A method for gluing artificial boards comprises the following steps: for the plywood, the plant glycosyl polyester adhesive as in claim 1 or 2 is coated on the surface of a veneer in a roller coating or spraying mode, and the coating amount is 100-250 g/m²Laminating a plurality of veneers into a plywood, cold-pressing at the pressure of 1.0MPa for 20-60 min, and then uniformly pressurizing at the temperature of 100-150 ℃ for 1-3.5 min/mm by adopting a hot press at the pressure of 1.0-2.5 MPa; for fiber boards and particle boards, fibers or wood shavings are mixed with the plant sugar-based polyester adhesive according to claim 1 or 2, and then hot-pressed and molded, wherein the hot-pressing temperature is 100-150 ℃.

10. Non-aldehyde modified wood, plywood, fiberboard and particle board prepared by using the plant sugar based polyester based adhesive of claim 1 or 2.

Technical Field

The invention relates to a plant glycosyl polyester adhesive as well as a preparation method and application thereof, in particular to an aldehyde-free wood polyester adhesive which can be used for preparing aldehyde-free modified wood, artificial board gluing and wood treatment, and belongs to the field of wood processing.

Background

Wood is a sustainable natural material, has excellent physical and mechanical properties, and the adhesive mainly used in the wood processing industry at present is "formaldehyde-type adhesive": phenolic resin, urea-formaldehyde resin and melamine formaldehyde resin have the problem of releasing toxic volatile matters such as aldehydes and ketones in the preparation, curing and using processes, and particularly in the field of home decoration, the harm of free formaldehyde to human health is generally recognized by the general public at present. Therefore, the development of nontoxic, pollution-free, green and environment-friendly wood adhesives is urgently needed.

The soybean-based wood adhesive and the starch-based adhesive have the advantages of low price, reproducibility and environmental protection, but have the defects of low bonding strength, poor water resistance and the like, and are not beneficial to practical application and popularization. CN 102230082B discloses a plant-based polyesterol adhesive prepared from bagasse powder, dihydric alcohol, dianhydride and a catalyst, but the main components of the raw materials are non-renewable raw materials such as the dihydric alcohol, the dianhydride and the like, and the plant-based bagasse powder is less than 15%. CN 102105544B discloses a polymer composition suitable for wood treatment or bonding, which is prepared by reacting maltodextrin and derivatives thereof serving as polyhydric alcohols with polybasic acid crosslinked polyester and is used for modifying or bonding wood. However, the adhesive obtained by the method is reactive, and the water resistance of the modified wood and the bonding strength of the bonded wood are poor, so that the requirements of high-quality modified wood and wood adhesive are difficult to meet.

Disclosure of Invention

In view of the problems in the prior art, the invention provides a polyester adhesive which takes maltodextrin, glucose or cyclodextrin and oxalic acid or succinic acid or polymaleic anhydride as main raw materials, the raw materials of the adhesive have wide sources and low cost, and have no pollution to the environment, and the adhesive can obtain higher bonding strength and water resistance through treatment of a curing agent and the like. Meanwhile, through polyester reaction, hydrophilic functional groups of the plant base can be removed through reaction, and the water resistance of the plant base adhesive is improved.

A plant glycosyl polyester adhesive comprises the following raw materials in parts by weight:

maltodextrin, glucose and/or cyclodextrin: 20-200 parts of a solvent;

oxalic acid, succinic acid and/or polymaleic anhydride: 40-300 parts;

water: 200-600 parts;

catalyst: 2-8 parts;

curing agent: 5-20 parts of a solvent;

coupling agent: 0-10 parts;

modifying agent: 0-80 parts;

water-proofing agent: 1-5 parts;

filling: 0-500 parts;

is prepared from maltodextrin, glucose and/or cyclodextrin (polyol) and oxalic acid, succinic acid and/or polymaleic anhydride (polyacid/anhydride) through polymerizing.

Maltodextrin, glucose and cyclodextrin are all polyols, and can react with polybasic acid (including dibasic acid) to generate polyester high polymer, and also can react with anhydride to generate polyester high polymer.

Wherein, after maltodextrin, glucose and/or cyclodextrin, part or all of oxalic acid, succinic acid and/or polymaleic anhydride, a catalyst and water are stirred and mixed, the rest other raw material components are added and uniformly mixed to obtain the reactive plant glycosyl polyester adhesive;

or stirring and mixing maltodextrin, glucose and/or cyclodextrin, oxalic acid, succinic acid and/or polymaleic anhydride, a catalyst and water, uniformly mixing, heating, adding the rest other raw material components, and heating again to obtain the plant glycosyl polyester adhesive.

Wherein the catalyst is benzene sulfonic acid, p-methyl benzene sulfonic acid, sodium dodecyl sulfate or sulfuric acid; is used for improving the reaction efficiency of the plant polysaccharide and the polybasic acid polyester.

The curing agent is a water-based isocyanate curing agent, water-based epoxy resin or polyimide and is used for reducing the curing time of the adhesive and improving the bonding strength.

The coupling agent is a silane coupling agent, a titanate coupling agent or an aluminate coupling agent and is used for improving the compatibility and stability of the adhesive.

The modifier is preservative, antibacterial agent, flame retardant, antistatic agent, antioxidant, coloring agent and/or ultraviolet ray protector, and is used to raise the performance of treated timber.

The waterproof agent is methyl potassium silicate, methyl sodium silicate and/or a fluorine silicon material and is used for improving the water resistance of the adhesive.

Wherein the filler is industrial starch, montmorillonite or calcium carbonate.

The invention provides a preparation method of the plant glycosyl polyester adhesive, which has the advantages of low cost, simple process and no pollution to the environment, and can obtain the aldehyde-free adhesive with higher bonding strength and water resistance.

A preparation method of the aldehyde-free plant glycosyl polyester adhesive comprises the following steps:

1) preparing materials according to the formula of the raw materials;

2) putting maltodextrin, glucose and/or cyclodextrin, part of oxalic acid, succinic acid and/or polymaleic anhydride, a catalyst and water into a reaction tank, stirring at room temperature, uniformly blending, then adding the rest oxalic acid, succinic acid and/or polymaleic anhydride, a curing agent, a coupling agent, a modifying agent, a waterproof agent and a filler, and uniformly mixing to prepare the low-viscosity reactive polyester adhesive;

or putting maltodextrin, glucose and/or cyclodextrin, oxalic acid, succinic acid and/or polymaleic anhydride, a catalyst and water into a reaction tank, stirring at room temperature, uniformly blending, then adding a curing agent, a coupling agent, a modifying agent, a waterproof agent and a filler, and uniformly mixing to prepare the low-viscosity reactive polyester adhesive;

or, adding part of oxalic acid, succinic acid and/or polymaleic anhydride, catalyst and water into maltodextrin, glucose and/or cyclodextrin, stirring at room temperature, uniformly blending, adding the rest oxalic acid, succinic acid and/or polymaleic anhydride, curing agent, coupling agent, modifier and waterproof agent, uniformly mixing, heating again, heating to 180 ℃ with 100 ℃, and preserving heat for 0.5-5 h; and then cooling, and adding a filler to prepare the viscous polyester adhesive.

In step 2), in the polyester reaction, the molar ratio of carboxyl groups in oxalic acid, succinic acid and/or polymaleic anhydride to hydroxyl groups in maltodextrin, glucose and/or cyclodextrin is in the range of: 1:5 to 20: 1; preferably 1.2:1 to 5:1, the excess carboxyl groups of the polyacid can react with hydroxyl groups in the wood. The chemical reaction forms a water insoluble polymer.

In the step 2), the temperature of reheating treatment after uniform mixing is 100-180 ℃, and the heat preservation time is 2-5 h.

The invention also provides the application of the plant glycosyl polyester adhesive in wood impregnation or bonding, and the adhesive can be used for preparing aldehyde-free modified wood and artificial board adhesive. The polyester adhesive enters the interior of the wood through an impregnation process, and then is subjected to chemical reaction through hot pressing, microwaves, high-energy radiation, ultraviolet radiation or any combination of the hot pressing, the microwaves, the high-energy radiation and the ultraviolet radiation, so that the adhesion is carried out; the polyester adhesive is coated on the surface of a wood veneer through roller coating, and then a chemical reaction is realized through hot pressing, microwave, high-energy radiation, ultraviolet irradiation or any combination of the hot pressing, the microwave, the high-energy radiation and the ultraviolet irradiation, so that the gluing is carried out, and the plywood is formed; the polyester adhesive is mixed with wood powder or wood shavings, and is hot-pressed to be adhered to form a fiber board or a shaving board.

A preparation method of aldehyde-free modified wood comprises the following steps: the polyester adhesive is used for impregnating the artificial fast-growing forest solid wood or the microwave-puffed wood, and the impregnated wood is cured at 100-180 ℃.

In the above method, the impregnation process employs a process well known to those skilled in the art, such as vacuum-pressure impregnation. Preferably, the vacuum degree is firstly pumped to be-0.1 to-0.05 MPa, and the holding time is 15 to 60 min; the dipping pressure is 0.5-2.0 MPa, preferably 1.0-2.0 MPa, and the pressure maintaining time is 1-72 h.

The curing of the impregnated wood can be achieved by hot pressing, microwave, high-energy radiation, ultraviolet radiation or any combination thereof to achieve chemical reaction, and then gluing is carried out; the preferred method is as follows: (1) putting the impregnated wood into an oven at 100-140 ℃ and curing for 10-24 h; or (2) putting the impregnated wood into a hot press, carrying out hot pressing for 15min-2h at the temperature of 100-140 ℃, taking out, and putting into a drying kiln for drying and shaping.

A method for gluing artificial boards comprises the following steps: the artificial board comprises plywood, a fiberboard and a flakeboard; for the plywood, the polyester adhesive is coated on the surface of the veneer in a roller coating or spraying mode, and the coating amount is 100-250 g/m²Laminating a plurality of veneers into a plywood, cold-pressing at the pressure of 1.0MPa for 20-60 min, and then uniformly pressurizing at the temperature of 100-150 ℃ for 1-3.5 min/mm by adopting a hot press at the pressure of 1.0-2.5 MPa; for fiber boards and shaving boards, fibers or shavings are mixed with the polyester adhesive, and hot-press molding is carried out at the hot-press temperature of 100-150 ℃.

Compared with the prior art, the plant glycosyl wood adhesive and the aldehyde-free modified wood have the outstanding characteristics that:

(1) compared with the prior art, the preparation process and the raw material proportion have obvious difference by taking glucose or cyclodextrin and oxalic acid or succinic acid or polymaleic anhydride as main raw materials. On one hand, a new application field is provided for cheap plant resources, the income of farmers is increased, and the cost of the aldehyde-free adhesive can be reduced; on the other hand, the wood adhesive can replace part of petroleum-based wood adhesives prepared from non-renewable resources such as petroleum.

(2) The water-based isocyanate and the water-based epoxy resin are selected as curing agents and the organic silicon is selected as a waterproof agent. The waterborne isocyanate curing agent is mature as a curing agent of waterborne polyurethane, and free isocyanate groups (-NCO) of the waterborne isocyanate curing agent can rapidly crosslink and cure hydroxyl groups in polyester adhesives and wood to form three-dimensional reticular high-molecular polymers, so that the bonding strength and the water resistance of the adhesives are improved. Free epoxy group (-CH (O) CH-) has strong reactivity, can quickly generate a cured product with a crosslinking structure, reduces the curing time, and simultaneously improves the bonding strength and the water resistance of the adhesive. The organosilicon waterproofing agent can react with CO in the air₂Or other acidic compounds react to form an insoluble reticular waterproof breathable film, so that the water resistance of the adhesive is improved.

(3) The preparation raw materials are wide in source, renewable, low in price and easy to obtain. The preparation conditions are not harsh, the process is simple, no harmful substances are discharged in the preparation and application processes, and the formaldehyde-free wood adhesive belongs to formaldehyde-free biomass-based wood adhesives and environment-friendly modified wood because the formaldehyde-free wood adhesive is free from formaldehyde.

Detailed Description

The present invention will be described in detail below with reference to examples, but the scope of the present invention is not limited to the following description.

The raw materials of the vegetable sugar-based polyester adhesive comprise water, maltodextrin or glucose or cyclodextrin, oxalic acid or succinic acid or polymaleic anhydride, a catalyst, a curing agent, a modifier, a waterproof agent, a filler and the like; the adhesive is a polyester adhesive and is formed by polymerizing one or two of maltodextrin, glucose and cyclodextrin and one or more of oxalic acid, succinic acid and polymaleic anhydride.

The plant glycosyl polyester adhesive is prepared by the following chemical reactions in parts by weight: maltodextrin or glucose or cyclodextrin: 100 parts of (A); oxalic acid or succinic acid or polymaleic anhydride: 100-300 parts; water: 300-600 parts of catalyst: 2-8 parts; coupling agent: 0-10 parts; curing agent: 5-20 parts of a solvent; modifying agent: 0-80 parts; water-proofing agent: 1-5 parts; filling: 0 to 500 parts.

The catalyst is selected from one of the following: benzene sulfonic acid, p-methyl benzene sulfonic acid, sodium dodecyl sulfate and sulfuric acid. The catalyst can improve the reaction efficiency of the plant polysaccharide and the polyacid polyester.

The curing agent is selected from one of the following: water-based isocyanate curing agent, water-based epoxy resin and polyimide. The curing agent can reduce the curing time of the adhesive and improve the bonding strength.

The coupling agent is selected from one of the following: silane coupling agent, titanate coupling agent and aluminate coupling agent. The coupling agent can improve the compatibility and stability of the adhesive.

The modifier comprises: the wood treatment agent comprises a preservative, an antibacterial agent, a flame retardant, an antistatic agent, an antioxidant, a coloring agent, an ultraviolet protective agent and the like, and is commonly used in the market to improve certain functional properties of treated wood.

The water repellent comprises: potassium methyl silicate and sodium methyl silicate. The waterproof agent can improve the water resistance of the adhesive.

The filler is selected from one of the following: industrial starch, montmorillonite and calcium carbonate.

The preparation method of the aldehyde-free plant glycosyl wood adhesive comprises the following steps: blending maltodextrin or glucose or cyclodextrin, oxalic acid or succinic acid or polymaleic anhydride and a catalyst according to a proportion, putting into a reaction tank, stirring at room temperature, and (1) blending uniformly at room temperature to form a transparent reactive polyester adhesive for impregnation; (2) after uniform blending, heating to 120-180 ℃, preserving heat for 2-5 h, and cooling to room temperature to prepare the viscous polyester adhesive for coating. The curing agent, the coupling agent, the modifier and the filler form other components according to the actual addition amount. When in use, the components are mixed for use.

In the polyester reaction, the molar ratio of carboxyl in oxalic acid, succinic acid or polymaleic anhydride to hydroxyl in maltodextrin, glucose or cyclodextrin is 1:5 to 20: 1; preferably 1.2:1 to 5:1, the excess carboxyl groups of the polyacid can react with hydroxyl groups in the wood. The chemical reaction forms a water insoluble polymer.

Aldehyde-free modified wood: the prepared reaction type polyester adhesive aqueous solution is used for impregnating the artificial fast-growing forest solid wood or the microwave expanded wood, and the impregnation process adopts a process which is well known by a person skilled in the art, such as vacuum-pressure impregnation. The impregnated wood is cured in two ways: (1) putting the impregnated wood into a drying oven at 100-140 ℃ and directly curing for 10-24 h; (2) and (3) putting the impregnated wood into a hot press, carrying out hot pressing for 15min-2h at the temperature of 100-140 ℃, taking out, putting into a drying kiln, and drying and shaping.

Gluing the artificial board: the adhesive is used for gluing three artificial boards (plywood, fiberboard and flakeboard), wherein the plywood can be coated with polyester adhesive on the surface of a veneer in a roller coating or spraying manner, and the glue coating amount is 100-250 g/m²The plywood is formed by laminating a plurality of veneers, cold pressing is carried out for 20-60 min at the pressure of 1.0MPa, and then uniform pressurization is carried out for 1-3.5 min/mm at the temperature of 150 ℃ at the pressure of 1.0-2.5 MPa in a hot press. The fiber board and the particle board are mixed with the reaction type polyester adhesive or the component type polyester adhesive through fibers or wood shavings, and are subjected to hot press molding at the hot press temperature of 100-.

The plywood, the shaving board, the fiber board and the modified wood using the polyester adhesive can be collectively called as a 'fruity board' or a 'fruity wood' because polyester high polymer easily emits various fruity smells.

Example 1

Adding 60 parts by mass of maltodextrin, 20 parts by mass of polymaleic anhydride and 4 parts by mass of benzenesulfonic acid into 400 parts by mass of water, mechanically stirring, and uniformly blending at normal temperature; then adding 60 parts by mass of oxalic acid, 20 parts by mass of water-based isocyanate curing agent and 1 part by mass of methyl potassium silicate waterproofing agent, and uniformly blending to form yellow micro-emulsion solution.

Selecting fast-growing poplar as treated wood, putting the poplar into an impregnation tank, firstly vacuumizing to the vacuum degree of-0.1 MPa, keeping for 30min, then injecting the synthesized reactive polyester adhesive into the impregnation tank until the liquid pressure of the impregnation tank is 1.5MPa, keeping for 10h, and then taking out.

Putting the impregnated poplar into a hot press, keeping the temperature at 140 ℃ for 40min under the pressure of 1.5MPa, and keeping the compression ratio of 20% by using a thickness gauge, cooling the impregnated poplar out of the press, and aging and maintaining the pressed modified wood at room temperature for more than 48 h.

Example 2

Adding 60 parts by mass of glucose, 60 parts by mass of oxalic acid and 4 parts by mass of benzenesulfonic acid into 400 parts by mass of water, mechanically stirring, and uniformly blending at room temperature (25 ℃); and adding 20 parts by mass of water-based isocyanate curing agent and 2 parts by mass of sodium methyl silicate waterproofing agent, and uniformly blending to obtain a white emulsion solution.

Selecting fast-growing poplar as treated wood, putting the poplar into an impregnation tank, firstly vacuumizing to the vacuum degree of-0.1 MPa, keeping for 30min, then injecting the synthesized reactive polyester adhesive into the impregnation tank until the liquid pressure of the impregnation tank is 1.5MPa, keeping for 10h, and then taking out.

Putting the impregnated poplar into a hot press, keeping the temperature at 140 ℃ for 40min under the pressure of 1.5MPa, and keeping the compression ratio of 20% by using a thickness gauge, cooling the impregnated poplar out of the press, and aging and maintaining the pressed modified wood at room temperature for more than 48 h.

Example 3

Adding 40 parts by mass of maltodextrin, 20 parts by mass of polymaleic anhydride and 2 parts by mass of p-toluenesulfonic acid into 300 parts by mass of water, mechanically stirring, uniformly blending, heating to 120 ℃, and keeping the temperature for 60 min; then adding 5 parts by mass of succinic acid, 30 parts by mass of polymaleic anhydride, 10 parts by mass of waterborne epoxy resin curing agent and 1 part by mass of potassium methylsilicate, preserving the heat at 140 ℃ for 30min, finally heating the temperature to 180 ℃, and preserving the heat for 2 h; cooling to normal temperature to prepare the polyester adhesive, and adding 100 parts by mass of industrial starch as a filler.

Coating aldehyde-free plant glycosyl adhesive on a single plate by roller at two sides, wherein the coating amount is 150g/m²The plywood is formed by laminating a plurality of veneers, cold pressing is carried out for 30min at the pressure of 1.0MPa, then uniform pressurization is carried out for 1.5min/mm at the temperature of 120 ℃ in a hot press at the pressure of 1.5MPa, and the pressed board is aged and cured for more than 48h at room temperature.

Example 4

Adding 40 parts by mass of glucose, 5 parts by mass of succinic acid, 50 parts by mass of oxalic acid and 2 parts by mass of p-toluenesulfonic acid into 300 parts by mass of water, mechanically stirring, uniformly blending, heating to 120 ℃, and keeping the temperature for 60 min; then 10 parts by mass of waterborne epoxy resin curing agent and 2 parts by mass of sodium methyl silicate are added, the temperature is kept at 140 ℃ for 30min, and finally the temperature is increased to 180 ℃ and kept for 2 h; cooling to normal temperature to prepare the polyester adhesive, and adding 100 parts by mass of industrial starch as a filler.

Coating aldehyde-free plant glycosyl adhesive on a single plate by roller at two sides, wherein the coating amount is 150g/m²The plywood is formed by laminating a plurality of veneers, cold pressing is carried out for 30min at the pressure of 1.0MPa, then uniform pressurization is carried out for 1.5min/mm at the temperature of 120 ℃ in a hot press at the pressure of 1.5MPa, and the pressed board is aged and cured for more than 48h at room temperature.

Table 1 comparison of parameters of modified wood prepared according to the present invention with those of ordinary modified wood, etc

TABLE 2 comparison of parameters of artificial boards made with the inventive vegetable sugar based polyester adhesives with artificial boards made with urea based adhesives

The invention takes maltodextrin, glucose or cyclodextrin and oxalic acid or succinic acid or polymaleic anhydride as main raw materials, and the raw materials are crosslinked into a polyester high polymer with a three-dimensional network structure under the action of a catalyst, a curing agent and a waterproof agent. The plant glycosyl polyester adhesive prepared by the invention has a compact three-dimensional network structure, high bonding strength, good water resistance and stable performance. The aldehyde-free modified wood and aldehyde-free artificial board prepared by the wood adhesive has low cost, is green and environment-friendly, and has good environmental benefit and economic benefit.

It should be noted that the above-mentioned embodiments are only embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, various changes and modifications can be made without departing from the spirit of the present invention, and these changes and modifications are within the scope of the present invention.