CN110587746A

CN110587746A - Complexing wood material and in-situ complexing method thereof

Info

Publication number: CN110587746A
Application number: CN201910890010.XA
Authority: CN
Inventors: 余养伦; 张世锋; 于文吉; 祝荣先
Original assignee: Research Institute of Wood Industry of Chinese Academy of Forestry
Current assignee: Research Institute of Wood Industry of Chinese Academy of Forestry
Priority date: 2019-09-20
Filing date: 2019-09-20
Publication date: 2019-12-20

Abstract

The invention relates to a complex wood material and an in-situ complexing method thereof, belonging to the technical field of wood processing. The in-situ complexing method for complexing the wood material takes the wood cells as the microreactor and is obtained by in-situ complexing plant polyphenol and metal salt in cell walls, cell cavities and cell gaps of the wood cells. The plant polyphenol-metal salt is introduced into cell walls, cell cavities and intercellular spaces of the wood material, and the plant polyphenol and the metal salt are fixed in the cells of the wood material by utilizing the complex reaction of the plant polyphenol and the metal salt, so that the wood material has the advantages of reducing cracking even not cracking, improving the dimensional stability, enhancing the texture layering, enriching the color and luster, preventing corrosion, preventing mildew and the like.

Description

Complexing wood material and in-situ complexing method thereof

Technical Field

The invention relates to the technical field of wood processing, in particular to a complex wood material and an in-situ complexing method thereof.

Background

Along with the technological progress and social development, the demand of human beings on wood materials is larger and larger, the application range is wider and wider, and the required quality is higher and higher. However, forest resources in China are deficient, and the inherent properties of wood materials make the wood materials difficult to meet the increasing market demands in the fields of products and applications.

Wood material products and wood materials have outstanding properties such as environmental properties-visual properties, tactile properties, auditory properties, olfactory properties and regulatory properties of wood materials, material properties-workability, high strength to weight ratio, thermal and electrical insulation, biological functions-renewability and degradability-which are well recognized by mankind, but their application is limited by swelling and drying shrinkage, cracking and deformation, decay and mildew, discoloration and the like of wood materials.

In the prior art, in order to prevent cracking of wood, a wood modification solution is generally used, for example, patent CN106182249A discloses a preparation method of high-strength wood with sterilization and cracking prevention, belonging to the technical field of wood treatment. The method comprises the steps of boiling wood, placing the wood into a pressure tank for blasting treatment, drying the wood after treatment to control the water content, soaking the wood in a wood modification solution, taking the soaked wood out, drying the wood, uniformly spraying a nano silica sol modified by hexadecyl trimethoxy silane on the surface of the wood, and drying the wood after spraying, wherein the wood modification solution is prepared by extracting and concentrating lily leaves and tea seed meal and preparing the allyl glycidyl ether, dimethyl acetamide, diethylene glycol, sodium hydroxide, diammonium hydrogen phosphate, cyproconazole and the like.

Aiming at the main defects of the wood material in the using process, people adopt physical and chemical technologies to carry out functional improvement, and the functional improvement comprises a wood material strengthening technology, a wood material size stability enhancing technology, a wood material anticorrosion and mildew-proof technology, a wood material discoloration prevention and dyeing technology and the like.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a complexing wood material and an in-situ complexing method thereof; the complex wood material prepared by the invention has the advantages of reducing cracking even not cracking, improving dimensional stability, enhancing texture layering, enriching color and luster, being antiseptic and mildew-proof, and the like.

In order to solve the technical problems, the invention provides the following technical scheme:

in one aspect, the invention provides a complexed wood material, wherein the plant polyphenol is combined with polysaccharide in the wood material through hydrogen bond to form a first structural unit; the metal salt and the plant polyphenol are combined through a coordination bond; the plant polyphenol is flavanol plant polyphenol to form a structural unit II; or the gallate plant polyphenol forms a structural unit III; the structural formulas of the structural unit I, the structural unit II and the structural unit III are as follows:

wherein, the plant polyphenol is reacted with each other through hydrogen bonds, such as:

the plant polyphenol and cellulose are reacted through hydrogen bonds, such as:

the plant polyphenol and water react through hydrogen bonds, such as:

water interacts with cellulose through hydrogen bonds, such as:

in the second structural unit and the third structural unit, M is one or more of iron, zinc, copper, aluminum, titanium, calcium, molybdenum, tungsten, chromium, magnesium and potassium; n is the number of valence electrons of the metal ion.

Further, the complexing wood material contains 0.3-15% of plant polyphenol and 0.1-12% of metal salt by mass, and the plant polyphenol and the metal salt exist in a complex form in cell walls, cell cavities and/or cell gaps of the wood material.

Preferably, the wood material is one or more of raw wood, sawn timber, laminated wood, cross-laminated wood, laminated veneer lumber, oriented strand board, laminated wood, plywood, reconstituted wood, flakeboard, fiberboard, plywood, veneer, wood beam, wood shavings and fiber.

On the other hand, the invention also provides an in-situ complexing method for complexing the wood material, which takes the wood cells as a microreactor and is obtained by in-situ complexing plant polyphenol and metal salt in cell walls, cell cavities and/or intercellular spaces of the wood cells.

The in-situ complexing method for complexing the wood material comprises the following steps:

step 1: preparing a proper amount of wood material;

step 2: introducing plant polyphenol and metal salt, and complexing to obtain a polyphenol metal salt wood material;

and step 3: and drying the polyphenol metal salt wood material to obtain the complex wood material.

Further, the step 2 is as follows: introducing plant polyphenol into cells of a woody material to obtain a polyphenol woody material; then introducing metal salt into polyphenol wood material cell, plant polyphenol and metal salt in cell wall and cell cavityAnd &Or in-situ complexing in intercellular spaces to obtain the polyphenol metal salt wood material;

or introducing metal salt into wood material cells to obtain a metal salt wood material; then plant polyphenol is introduced into the wooden material cell of metal salt, and the metal salt and the plant polyphenol are introduced into the cell wall and the cell cavityAnd &Or in-situ complexing in intercellular spaces to obtain the polyphenol metal salt wood material;

or simultaneously introducing plant polyphenol and metal salt into the cell wall, cell cavity or intercellular space of the woody material, wherein the metal salt and the plant polyphenol are introduced into the cell wall and cell cavityAnd &Or in-situ complexing in intercellular spaces to obtain the polyphenol metal salt wood material.

Further, the step of introducing the plant polyphenol into the wood cells specifically comprises:

21) dissolving plant polyphenol in water, and stirring uniformly to form a plant polyphenol water solution;

22) soaking the wood material in plant polyphenol water solution;

23) drying the wood material impregnated with the aqueous solution of plant polyphenol.

Preferably, the concentration of the plant polyphenol water solution is 1-25.0 g/L, the average molecular weight is 170-50000, and the plant polyphenol water solution is 1-40 polymers; the wood material is soaked in plant polyphenol water solution for 10min-48h at 0-80 deg.C under normal pressure, pressure or vacuum pressure.

Preferably, the plant polyphenol is one or more of tannin extract, tannin, tannic acid, terminal food acid and pyrogen terminal food acid.

Further, the introduction of the metal salt into the wood cells specifically comprises:

24) dissolving metal salt in water, and stirring uniformly to form a metal salt water solution;

25) the wooden material is immersed in an aqueous solution of a metal salt.

Preferably, the concentration of the metal salt aqueous solution is 0.3 g/L-30.0 g/L, and the pH value is 3.5-4.5; the wood material is soaked in the metal salt water solution for 10min to 180 days at the soaking temperature of 0 to 80 ℃, and the soaking method is a normal pressure soaking method, a pressure soaking method or a vacuum pressure soaking method.

Preferably, the metal salt is one or more of iron salt, zinc salt, copper salt, aluminum salt, titanium salt, calcium salt, molybdenum salt, tungsten salt, chromium salt, magnesium salt, potassium salt, and double salts thereof.

The existing research considers that the cracking of the wood material is caused by a plurality of reasons, wherein the main factor is that polysaccharides (cellulose, hemicellulose and the like) in the wood material absorb or release water in the processes of moisture absorption and desorption to cause the expansion or shrinkage of the wood material, so that the size of the wood material is unstable and the cracking is caused.

Compared with the prior art, the invention has the following beneficial effects:

in the invention, the plant polyphenol is obtained by in-situ complexing plant polyphenol and metal salt by taking the wooden cells as a microreactor. According to the invention, plant polyphenol and metal salt are introduced into the cell wall of the wood material, phenolic hydroxyl groups of the plant polyphenol are combined with hydroxyl groups of cellulose and hemicellulose, meanwhile, ortho-position phenolic hydroxyl groups are complexed with metal ions, and molecular chains of adjacent cellulose/hemicellulose are crosslinked into a net structure, just as a plurality of supports are supported on the molecular chain branches of the cellulose/hemicellulose, so that the expansion or contraction of the molecular chains is reduced or even not generated during moisture absorption or desorption; on the basis, a large number of multiple sacrificial bond networks consisting of hydrogen bonds (the plant polyphenol phenolic hydroxyl groups are combined with hydroxyl groups in the wood material to form multi-point hydrogen bonds) and coordination bonds (the ortho hydroxyl groups on the plant polyphenol phenolic rings are complexed with metal salts to form coordination bonds) are formed in the cellulose skeleton. Because the sacrificial bond energy is less than the covalent bonds (covalent bond network is formed between cellulose, hemicellulose, lignin and phenolic resin), the sacrificial bonds break in preference to the covalent bonds when the wood material is subjected to internal or external stresses. The dynamic action of the continuous breakage and reconstruction of the sacrificial bonds dissipates a large amount of energy in a wood material system, eliminates or weakens internal stress, and protects the integrity of a cellulose skeleton covalent bond network. This provides a new approach to solving the cracking problem of wood materials.

Firstly, introducing plant polyphenol and/or metal salt into a wood material to swell the wood material; then introducing metal salt and/or plant polyphenol into the wood material, wherein the plant polyphenol is combined with cellulose and hemicellulose in the wood material to form a multi-point hydrogen bond, and meanwhile, the plant polyphenol and the metal salt are subjected to in-situ complexation to combine the 'cellulose-plant polyphenol-metal salt' into a whole just like forming a plurality of bracket supports in a cellulose skeleton molecule and forming steric hindrance between cellulose and/or hemicellulose skeletons; then, after drying, the concentration of the plant polyphenol and the metal salt is increased along with the evaporation of water, the water in the cell wall is replaced by a drying medium, the oxygen content is increased, and the cellulose-plant polyphenol-metal salt is promoted to be further crosslinked and oxidized to finally form the complex wood material. The dynamic multiple sacrificial bond network structure of the cellulose-plant polyphenol-metal salt forms steric hindrance between cellulose and/or hemicellulose frameworks, so that the dynamic effect of continuous fracture and reconstruction of the sacrificial bonds is realized, a large amount of energy in a wood material system is dissipated, internal stress is eliminated or weakened, the integrity of the covalent bond network of the cellulose framework is protected, and the problem that the wood material is easy to crack at a molecular level is solved.

According to the invention, the metal salt is subjected to in-situ complexation through the plant polyphenol and is fixed in the wood material cell in situ, and the metal salt has good functions of mildew resistance, corrosion resistance, flame retardance, color change and the like, so that the wood material is endowed with the functions of mildew resistance, corrosion resistance, flame retardance, color change and the like.

Drawings

FIG. 1 is a diagram of a dry shrinkage and wet swelling molecular chain of a cell wall cellulose skeleton in the prior art;

FIG. 2 is a molecular chain structure diagram of the complex wood material cellulose framework in dry and wet states;

FIG. 3 is a drawing of birch, poplar and beech sawn timber untreated and treated in example 1 of the present invention;

fig. 4 is an electronic scanning and energy spectrum of poplar complex wood according to example 1 of the present invention, fig. 4a is an electronic scanning and carbon, oxygen, aluminum and potassium energy spectrum, fig. 4b is a distribution diagram of aluminum ions in poplar cells, and fig. 4c is a distribution diagram of potassium ions in poplar cells;

FIG. 5 is a CT image of poplar complex wood in example 1 of the present invention;

FIG. 6 is a graph of untreated oak, eucalyptus, persimmon and larch logs treated in accordance with example 3 of the present invention;

FIG. 7 is a diagram of a laminated veneer lumber in example 4 of the present invention;

FIG. 8 is a diagram of a laminated veneer in example 5 of the present invention;

FIG. 9 is a comparison of contact angle and surface before and after treatment of eucalyptus veneer in example 6 of the present invention.

Detailed Description

In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following detailed description is given with reference to specific embodiments.

In the present invention, the materials and reagents used are not specifically described, and are commercially available.

The invention provides a complexing wood material and an in-situ complexing method thereof, and the specific embodiment is as follows.

Example 1

A complex sawn timber and a preparation method thereof comprise the following steps:

step 1: preparing proper amount of sawn timber

Cutting birch, poplar, beech and camphor tree into wood sections with the length of 200cm, processing the wood sections into sawn timber with a certain specification after sawing, and controlling the absolute water content to be 20% after drying;

step 2: guiding the Acacia Negra extract into the sawn timber

Dissolving a Acacia Negra extract in water, and stirring uniformly to form a semi-colloidal aqueous solution with coexisting molecular dispersion state and molecular aggregation state, wherein the concentration is 20 g/L;

then soaking the wood prepared in the step 1 in the acacia mearnsii tannin extract solution; adopting pressure impregnation, wherein the impregnation time is 12h, the impregnation temperature is 25 ℃, the pressure is 1.0MPa, controlling by hydraulic pressure flow to ensure that the impregnation amount of tannin is 5.2% of the wood mass, taking out the sawn timber, placing the sawn timber in a drying kiln for drying, gradually evaporating water in the sawn timber, controlling the water content of the sawn timber, and taking out the sawn timber when the absolute water content is 40% to form polyphenol sawn timber;

and step 3: introduction of metal salts into polyphenol sawn timber

Dissolving aluminum potassium sulfate in the aqueous solution, and uniformly stirring to form an aluminum potassium sulfate aqueous solution with the concentration of 3.0 g/L;

soaking the polyphenol sawn timber prepared in the step 2 in the aluminum potassium sulfate aqueous solution in the step 3, adopting pressure impregnation, wherein the impregnation temperature is 25 ℃, the impregnation pressure is 1.0MPa, the impregnation time is 12h, controlling the flow to ensure that the impregnation amount of aluminum potassium sulfate is 2.5 percent of the mass of the timber, and taking out the polyphenol sawn timber to form the polyphenol aluminum potassium composite salt sawn timber;

and 4, step 4: dry polyphenol aluminum potassium composite salt sawn timber

And placing the wood into a drying kiln, gradually evaporating the water in the polyphenol aluminum potassium composite salt sawn timber by adopting a conventional drying method, and taking out the wood when the absolute water content is 6-12% to obtain the complex sawn timber.

The cracking of wood is caused by many reasons, and the most important factor is that polysaccharides (cellulose, hemicellulose and the like) in wood absorb or release water during the processes of moisture absorption and desorption to cause the expansion or contraction of wood, as shown in fig. 1, thereby causing dimensional instability and cracking of wood.

According to the invention, plant polyphenol and metal salt are introduced into the cell wall of sawn timber, phenolic hydroxyl groups of the plant polyphenol are combined with hydroxyl groups of lignin material polysaccharide (cellulose and hemicellulose) to form hydrogen bonds, so that the plant polyphenol is fixed in the cell wall, meanwhile, in-situ complexation reaction is carried out on the ortho-position phenolic hydroxyl groups and metal ions, and adjacent cellulose/hemicellulose molecular chains are crosslinked into a net structure, as if a plurality of supports are supported on the cellulose/hemicellulose molecular chain, and steric hindrance is formed between the cellulose and/or hemicellulose frameworks, so that the expansion or contraction is reduced or even not generated when the cellulose and/or hemicellulose frameworks absorb moisture or desorb, as shown in figure 2.

Comparing the complex sawn timber obtained by the method of the embodiment before and after the treatment, as can be seen from fig. 3, the unprocessed sawn timber has more cracks, and the surface cracks of the complex sawn timber obtained after the treatment are obviously reduced, even no cracks.

The chordwise and radial shrinkage coefficients of the sawn timber before and after treatment were also measured, as shown in table 1. As can be seen from table 1, the untreated wood, both chordwise and radial shrinkage rates, demonstrated shrinkage deformation of the sawn timber, while the treated sawn timber, both chordwise and radial shrinkage rates, were much less than the untreated sawn timber, with good dimensional stability.

TABLE 1 complexing 4 sawn timber drying shrinkage factor

The complexed sawn timber prepared in the above example contains 5.2% by weight of plant polyphenol and 2.5% by weight of metal salt, and as can be seen from the electron scanning and energy spectrum diagrams of fig. 4, aluminum ions and potassium ions are impregnated into the cell walls of the poplar sawn timber, and as can be seen from fig. 5, the plant polyphenol and metal salt complex are uniformly distributed in the cell walls, cell cavities and intercellular spaces of the sawn timber.

Example 2

A preparation method of a complexing sawn timber comprises the following steps:

step 1: preparing sawn timber;

cutting birch log into sawn timber with length of 200cm, width of 12cm and thickness of 2.0 cm;

step 2: preparation of plant polyphenol metal salt solution

21) Dissolving gallic acid in water, and stirring to obtain tannic acid water solution with concentration of 10 g/L; the average molecular weight is 170;

22) dissolving zinc borate in water, and uniformly stirring to form a zinc borate aqueous solution with the concentration of 6 g/L;

23) mixing the zinc borate aqueous solution obtained in the step 22) according to a ratio of 1: 1, pouring the mixture into the plant polyphenol water solution obtained in the step 21) to form a plant polyphenol zinc borate solution;

and step 3: introduction of plant polyphenol zinc borate

31) Dipping the sawn timber in the step 1 into the plant polyphenol zinc borate salt solution in the step 2, and adopting vacuum pressure dipping, wherein the birch sawn timber is firstly vacuumized and then is dipped under pressure, the vacuum degree in the vacuumization is-0.10 PMa, the dipping pressure is 1.20MPa, the dipping time is 12h, and the dipping temperature is 63 ℃;

and 4, step 4: and drying the polyphenol metal salt sawn timber to obtain the complex sawn timber.

And taking out the polyphenol metal salt sawn timber, and drying in the drying process, wherein the water content is controlled to be 12%, so that the complex sawn timber is formed.

According to the method specified in GB/T13942.1, the antiseptic property of untreated birch and complex birch is measured, and after the complex treatment, the antiseptic property of the complex birch reaches level 1; according to the method specified in GB/T18261, the mildew resistance of the complex birch is measured, and the mildew resistance reaches grade 1; the termite resistance of the complexed birch was measured according to the method specified in GB/T18260. Because the boron is fixed in the wooden cell wall, the boron can not be lost, and the in-situ boron is fixed in the cell, thereby having good functions of corrosion prevention, mildew prevention and termite prevention.

Example 3

A method for preparing a complexed log comprises:

step 1: preparing proper amount of log

Cutting fresh oak, eucalyptus, persimmon and larch into 200cm long wood sections, and removing bark to obtain log;

step 2: introducing metal salt into raw wood

Dissolving aluminum sulfate in the water solution, and uniformly stirring to obtain an aluminum sulfate solution with the concentration of 3.0 g/L;

putting the log prepared in the step 1 into a pressure container, soaking the log in an aluminum sulfate solution, adopting vacuum pressurization dipping, vacuumizing a test piece (absolute pressure is 8kPa) for 1h, injecting the aluminum sulfate solution, soaking for 8h, then applying pressure (pressure is 1.5MPa), dipping for 12h, taking out the log, and standing for 10-15 days under the aerobic condition with the water content of 60% to obtain an aluminum salt log;

and step 3: introduction of tannic acid into aluminium sulfate salt log

Dissolving tannic acid in water, and stirring to obtain tannic acid colloid;

soaking the aluminum salt log prepared in the step 2 in tannic acid colloid for 4 hours at 25 ℃ under 0.3MPa for 4 hours under pressure, taking out the iron salt log, drying the iron salt log in a drying kiln to gradually evaporate water in the log, controlling the water content of the log, and taking out the log when the absolute water content is 32% to form polyphenol aluminum salt log;

and 4, step 4: dried plant polyphenol aluminum salt log

And (3) placing the plant polyphenol aluminum salt log in a drying kiln or air to gradually evaporate water in the log, introducing oxygen into the drying kiln when the absolute water content of the polyphenol metal salt log is 50%, adjusting the oxygen content in a drying medium to be 30%, introducing carbon dioxide when the absolute water content of the polyphenol metal salt log is 25%, adjusting the oxygen content in the drying medium to be normal air oxygen content until the absolute water content of the polyphenol metal salt log is 12%, and thus obtaining the complex log.

The complex wood prepared in the above example contains 5% by weight of plant polyphenol and 3.2% by weight of metal salt.

Before and after the wood treatment in this example, as shown in fig. 6, the complex wood obtained by the method of the present invention has no crack on the surface and good wood stability.

The chordwise and radial shrinkage coefficients of the logs before and after treatment were also measured as shown in table 2. As can be seen from table 2, the untreated log has a higher dry shrinkage in the chord direction and the radial direction, which proves that the log is more susceptible to shrinkage deformation, while the treated log has a much lower dry shrinkage in the chord direction and the radial direction than the untreated sawn timber, which has a good dimensional stability.

TABLE 2 complexing 4 log drying shrinkage coefficients

Example 4

A complex laminated veneer lumber and a preparation method thereof comprise the following steps:

step 1: preparing a proper amount of laminated veneer lumber

The poplar is made into a laminated veneer lumber (belonging to the conventional process) according to the laminated veneer lumber process, and the cut size is 2460 multiplied by 150mm square lumber;

step 2: introducing plant polyphenols into laminated veneer lumber

Dissolving the Marxist tannin extract in an aqueous solution, and uniformly stirring to form a semi-colloidal aqueous solution with coexisting molecular dispersion state and molecular aggregation state, wherein the concentration is 6.0 g/L;

then soaking the laminated veneer lumber prepared in the step 1 in the Mabushi tannin extract solution; adopting pressure impregnation, wherein the impregnation time is 4h, the temperature is 25 ℃, the pressure is 0.80MPa, the impregnation amount of tannin is 6% of the mass of the laminated veneer lumber, taking out the laminated veneer lumber, placing the laminated veneer lumber in a drying kiln or air, gradually evaporating the moisture in the laminated veneer lumber, and taking out the laminated veneer lumber when the absolute moisture content of the laminated veneer lumber is 12% to form the polyphenol laminated veneer lumber;

and step 3: introduction of zinc borate into a polyphenol laminated veneer lumber

Dissolving zinc borate in the aqueous solution, and uniformly stirring to form a zinc borate aqueous solution with the concentration of 4.5 g/L;

soaking the polyphenol laminated veneer lumber prepared in the step 2 in the zinc borate solution in the step 3 for 12 hours at 25 ℃, soaking by adopting hydraulic pressure at the pressure of 1.0MPa to ensure that the soaking amount of ferric chloride is 6.0 percent of the mass of the wood material, and taking out the plant polyphenol laminated veneer lumber;

and 4, step 4: dry polyphenol zinc borate laminated veneer lumber

Placing in a drying kiln at 60 deg.C to gradually evaporate water in the recombined wood to an absolute water content of 6-12% to obtain the complex laminated veneer lumber, as shown in FIG. 7.

The complex wooden material prepared in the above example contains 4.8% by weight of plant polyphenol and 5.9% by weight of zinc salt.

The static bending strength, elastic modulus, water absorption width expansion rate, and fire resistance of the laminated veneer lumber before and after treatment were measured at the same time, as shown in table 3. As can be seen from table 3, the density, static bending strength and elastic modulus of the untreated and complexed laminated veneer lumber were increased; after the complexing treatment, the water absorption thickness expansion rate of the laminated veneer lumber is obviously reduced, and the dimensional stability is greatly improved; the flame retardant performance is improved from B2 grade to B1 grade.

TABLE 3 comparison of Performance of the veneered laminate before and after complexing

Performance index	Control sample	Complex veneer laminated timber
			Air-dried Density (g/cm)³)	0.43	0.48
Flexural Strength (MPa)	67.0	74.5
			Modulus of elasticity (GPa)	10.3	11.2
Water absorption thickness expansion ratio (%)	8.9	3.2
			Water absorption width expansion ratio (%)	4.5	1.8
Flame retardant properties	Stage B2	Stage B1

Example 5

A complex laminated wood and a preparation method thereof comprise the following steps:

step 1: preparing a proper amount of laminated wood

Processing poplar into laminated wood according to a laminated wood manufacturing process (belonging to a conventional process), and cutting the laminated wood into battens with the length of 2000 multiplied by 150 mm;

step 2: introducing acid into glued wood

Dissolving terminal food acid in water, and stirring to obtain terminal food acid water solution with concentration of 1.8 g/L;

then, soaking the laminated wood prepared in the step 1 in the terminal seed acid aqueous solution; soaking for 8h at 25 deg.C under 0.6MPa to make the soaking amount of terminal seed acid be 3.0% of the mass of the wood material, taking out the laminated wood, placing in air to gradually evaporate water, and taking out when the absolute water content of the laminated wood is 50% to obtain polyphenol laminated wood;

and step 3: introduction of copper sulfate and copper alkylamine into tannin-introduced veneer

Copper sulfate and copper ammonia-soluble Alkylamine (ACQ) were mixed in a ratio of 1: 1 proportion is dissolved in the water solution, and after being uniformly stirred, a copper salt water solution with the concentration of 4.5g/L is formed;

soaking the polyphenol laminated wood prepared in the step 2 in the copper salt solution in the step 3 for 2h at 5 ℃, soaking by adopting hydraulic pressure at 0.4MPa to ensure that the impregnation amount of the copper salt is 5.5 percent of the mass of the wood material, and taking out the laminated wood;

and 4, step 4: drying the laminated wood into which the plant polyphenol and the metal salt have been introduced

Placing in air to gradually evaporate water to an absolute water content of 6-12% to obtain the complex laminated wood, as shown in FIG. 8.

The complex wooden material prepared in the above example contains 3.0% by weight of plant polyphenol and 5.5% by weight of copper salt.

The static bending strength, elastic modulus, water absorption width expansion rate, mold resistance, corrosion resistance and copper ion loss properties of the laminated veneer lumber before and after treatment were also measured, as shown in table 4. As can be seen from table 4, the density, static bending strength and elastic modulus of the untreated and complexed laminated wood increased; after the complexing treatment, the water absorption thickness expansion rate of the laminated veneer lumber is obviously reduced, and the dimensional stability is greatly improved; the corrosion resistance and the mildew resistance are obviously improved, and the loss resistance of copper ions is obviously improved.

TABLE 4 comparison of properties of poplar veneers before and after complexing

Performance index	Control sample	Complexing poplar sawn timber
			Air-dried Density (g/cm)³)	0.45	0.51
Flexural Strength (MPa)	57.8	64.4
			Modulus of elasticity (GPa)	10.7	11.1
Water absorption thickness swelling (%)	8.6	2.3
			Water absorption thickness swelling (%)	6.8	1.3
Mildew resistance	4 stage	Stage 2
			Corrosion resistance	IV grade (non-corrosion)	II level (Corrosion resistant)
Loss of copper ion	—	8％

Example 6

A complex veneer and a preparation method thereof comprise the following steps:

step 1: preparing a proper amount of veneer

Cutting eucalyptus wood into 2560cm wood sections, rotary cutting into veneers with the thickness of 1.5mm, and drying to control the water content to be 15%;

step 2: introducing copper chloride and magnesium chloride into a single plate

Copper chloride and magnesium chloride are mixed according to a mass ratio of 2: 1 proportion is dissolved in water, and after being uniformly stirred, an aqueous solution with the concentration of copper chloride and magnesium metal ions being 3.0g/L is formed;

soaking the veneer obtained in the step 1 in an aqueous solution of copper chloride and magnesium for 30min at room temperature, adopting pressurized impregnation at the pressure of 0.4MPa to ensure that the impregnation amount of the copper chloride and the magnesium is 1.2% of the mass of the veneer, taking out the veneer, keeping the water content of the veneer between 30% and 90%, and standing the veneer in an aerobic state for 10 to 15 days to obtain a metal salt veneer;

and step 3: valonea extract leading-in metal salt veneer

Dissolving valonea extract in water, and stirring uniformly to form valonea extract water solution with the concentration of 0.3 g/L;

then soaking the metal salt veneer prepared in the step 2 in the valonea extract solution; the dipping time is 30min, the temperature is room temperature, pressurized dipping is adopted, the pressure is 0.3MPa, the dipping amount of the valonea extract is 0.3 percent of the mass of the wood material, the veneer is taken out and placed in a drying kiln, the moisture in the veneer is gradually evaporated, and when the absolute moisture content of the veneer is 12 percent, the veneer is taken out to form a polyphenol metal salt veneer;

and 4, step 4: drying the veneer into which the plant polyphenol metal salt has been introduced

And placing the veneer in air to gradually evaporate the water in the veneer, wherein the absolute water content is 6-12%, and obtaining the complex veneer.

The complex wooden material prepared in the above example contains 2% by weight of plant polyphenol and 0.6% by weight of metal salt.

The eucalyptus veneer is processed by the method, as shown in fig. 9, and a contact angle test shows that the surface of the eucalyptus veneer before processing is hydrophilic, the surface of the processed eucalyptus veneer has better hydrophobic property, and the surface of the processed eucalyptus veneer has no crack and has good stability.

In conclusion, the plant polyphenol is introduced and fixed in the wood material, and the cellulose and/or the hemicellulose are supported, so that the expansion and the drying shrinkage are not caused in the processes of moisture absorption and desorption, and the wood material has better stability.

The foregoing is a preferred embodiment of the present invention, and it will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the principles of the invention and are intended to be within the scope of the invention.

Claims

1. A complex wood material is characterized in that plant polyphenol is combined with polysaccharide in the wood material through hydrogen bonds to form a first structural unit; the metal salt and the plant polyphenol are combined through a coordination bond; the plant polyphenol is flavanol plant polyphenol to form a structural unit II; or the gallate plant polyphenol forms a structural unit III; the structural formulas of the structural unit I, the structural unit II and the structural unit III are as follows:

2. The complexed wood-based material according to claim 1, wherein said complexed wood-based material comprises 0.3 to 15% by mass of the plant polyphenol and 0.1 to 12% by mass of the metal salt, said plant polyphenol and metal salt being present as a complex in the cell walls, cell cavities and intercellular spaces of said wood-based material.

3. The complexed wood-based material of claim 1, wherein said wood-based material is selected from the group consisting of logs, sawn timber, laminated wood, cross-laminated wood, laminated veneer lumber, oriented strand board, laminated wood, plywood, reconstituted wood, particle board, fiber board, plywood, veneer, wood strands, wood shavings, and fibers.

4. An in-situ complexing method for complexing wood materials is characterized in that wood cells are used as a microreactor, and plant polyphenol and metal salt are subjected to in-situ complexing in cell walls, cell cavities and/or intercellular spaces of the wood cells.

5. The method of in situ complexing of complexed wood material of claim 4, comprising:

step 1: preparing a proper amount of wood material;

6. The in situ complexing method for complexing wood-based material according to claim 5, wherein said step 2 is: introducing plant polyphenols into cells of the woody material; then introducing metal salt into the wood material cells, and carrying out in-situ complexation on the plant polyphenol and the metal salt in cell walls, cell cavities and/or cell gaps to obtain the polyphenol metal salt wood material;

alternatively, introducing a metal salt into cells of the woody material; then introducing the plant polyphenol into the wood material cells, and carrying out in-situ complexation on the metal salt and the plant polyphenol in cell walls, cell cavities and/or cell gaps to obtain the polyphenol metal salt wood material;

or synchronously introducing plant polyphenol and metal salt into the cell wall, the cell cavity or the intercellular space of the wooden material, and carrying out in-situ complexation on the metal salt and the plant polyphenol in the cell wall, the cell cavity and/or the intercellular space to obtain the polyphenol metal salt wooden material.

7. The method of claim 6, wherein the step of introducing the plant polyphenol into the cells of the woody material comprises:

22) soaking the wood material in plant polyphenol water solution;

8. The in-situ complexing method for complexing wood material according to claim 7, wherein said aqueous solution of plant polyphenol has a concentration of 1-25.0 g/L, an average molecular weight of 170-50000, and is 1-40 polymer; the wood material is soaked in the plant polyphenol water solution for 10min to 48h at the temperature of 0 to 80 ℃, and the soaking method is a normal pressure soaking method, a pressure soaking method or a vacuum pressure soaking method;

the plant polyphenol is one or more of tannin extract, tannin, tannic acid, terminal food acid, and charred terminal food acid.

9. The in situ complexation method according to claim 6, wherein the introducing of the metal salt into the wood material cell is specifically:

25) the wooden material is immersed in an aqueous solution of a metal salt.

10. The in situ complexing method for complexing wood-based material according to claim 9, wherein said aqueous metal salt solution has a concentration of 0.3g/L to 30.0g/L and a pH of 3.5 to 4.5; the wood material is soaked in the metal salt water solution for 10min to 180 days at the soaking temperature of 0 to 80 ℃, and the soaking method is a normal pressure soaking method, a pressure soaking method or a vacuum pressure soaking method;

the metal salt is one or more of iron salt, zinc salt, copper salt, aluminum salt, titanium salt, calcium salt, molybdenum salt, tungsten salt, chromium salt, magnesium salt, potassium salt and complex salt thereof.