阅读说明：本技术 一种络合木束、络合重组木及其制备方法 (Complex wood bundle, complex recombined wood and preparation method thereof ) 是由 余养伦 于文吉 祝荣先 吕斌 于 2019-09-20 设计创作，主要内容包括：本发明涉及一种络合木束、络合重组木及其制备方法,属于木材加工技术领域。上述络合木束的制备方法,包括：步骤1：准备适量木束；步骤2：把植物多酚导入木束,得到多酚木束；步骤3：在多酚木束中导入金属盐,得到多酚金属盐木束；步骤4：干燥多酚金属盐木束,得到络合木束。利用本发明的络合木束制备的络合重组木解决了现有技术中重组木容易出现跳丝、变形、开裂等问题,且保持较好的力学性能。(The invention relates to a complex wood bundle, a complex recombined wood and a preparation method thereof, belonging to the technical field of wood processing. The preparation method of the complex wood beam comprises the following steps: step 1: preparing a proper amount of wood bundles; step 2: introducing plant polyphenol into wood bundle to obtain polyphenol wood bundle; and step 3: introducing metal salt into the polyphenol wood bundles to obtain polyphenol metal salt wood bundles; and 4, step 4: and drying the polyphenol metal salt wood bundles to obtain the complex wood bundles. The complex recombined wood prepared by the complex wood bundle solves the problems that the recombined wood in the prior art is easy to have wire jumping, deformation, cracking and the like, and keeps better mechanical property.)

1. A preparation method of a complex wood bundle is characterized by comprising the following steps:

step 1: preparing a proper amount of wood bundles;

step 2: introducing plant polyphenol into wood bundle to obtain polyphenol wood bundle;

and step 3: introducing metal salt into the polyphenol wood bundles to obtain polyphenol metal salt wood bundles;

and 4, step 4: and drying the polyphenol metal salt wood bundles to obtain the complex wood bundles.

2. The method for preparing the complex wood strand according to claim 1, wherein the step 1 is specifically as follows:

11) sawing the log into wood sections with certain length;

12) rotary cutting or slicing the wood sections into veneers with certain thickness;

13) untwining the single boards to form wood bundles;

14) drying the wood beam until the water content is 6-30%.

3. The method for preparing the complex wood strand according to claim 1, wherein the step 2 is:

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

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

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

4. The method of preparing the complex wood bunch according to claim 3, wherein the concentration of the plant polyphenol water solution is 1.0g/L to 25.0g/L, the average molecular weight is 170 to 50000, and the plant polyphenol water solution is 1 to 40 polymers; the wood bundle is soaked in the plant polyphenol water solution for 10min to 48h at the soaking temperature of 0 to 80 ℃, and the soaking method is normal pressure, pressurization or pressurization after vacuum pumping; the plant polyphenol is one or more of tannin extract, tannin, tannic acid, terminal food acid, and charred terminal food acid.

5. The method for preparing the complex wood strand according to claim 1, wherein the step 3 is:

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

32) immersing the polyphenol wood bunch in a metal salt aqueous solution.

6. The method for preparing the complex wood bunch according to claim 5, wherein the concentration of the metal salt aqueous solution is 0.3g/L to 30.0 g/L; the wood bundle 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 normal pressure, pressurization or pressurization after vacuum pumping; the metal salt is one or more of iron salt, copper salt, aluminum salt, titanium salt, calcium salt, molybdenum salt, tungsten salt, chromium salt, magnesium salt, potassium salt and double salts thereof.

7. A complex wood bunch, characterized in that the wood bunch contains 0.3-15% by weight of plant polyphenol and 0.1-12% by weight of metal salt, and the plant polyphenol and the metal salt are distributed on surfaces, cell walls, cell cavities and/or intercellular spaces of the fluffed wood bunch and exist in the form of a complex.

8. A method for producing a recombined wood complex, wherein the wood complex obtained by the method according to any one of claims 1 to 6 or the wood complex of claim 7 is used as a raw material, and the method comprises:

step 1: sizing

Dipping phenolic resin or urea-formaldehyde resin into the complex wood beam by adopting a gum dipping mode or coating the phenolic resin or the urea-formaldehyde resin on the surface of the complex wood beam by adopting a roll coating mode, wherein the gum application amount is 8-30%;

step 2: drying

Drying the impregnated complex wood bundles in a drying kiln at the drying temperature of 45-75 ℃ and controlling the drying water content at 10-16%;

and step 3: assembly

Assembling the dried complex wood bundles according to the same grain to form a complex recombined wood plate blank;

and 4, step 4: glue synthetic type

Feeding the recombined wood slab into a cold press, and performing cold pressing to prepare a complex recombined wood square stock at the pressure of 30-100MPa and the cold pressing temperature of normal temperature; sending the mixture into a curing channel for curing, wherein the curing temperature is 135-155 ℃, and the curing time is 8-12 h;

or sending the recombined wood board blank into a hot press, and adopting a cold-in and cold-out process, wherein the hot pressure is 6-10MPa, the hot-pressing temperature is 135-.

9. The complex restructured wood is characterized in that the complex restructured wood is formed by stacking a plurality of layers of complex wood bundles according to the grain, an adhesive, and phenolic resin or urea-formaldehyde resin are arranged between each layer of complex wood bundles; the complex wood bundle contains 0.3-15 wt% of plant polyphenol and 0.1-12 wt% of metal salt, and the plant polyphenol and the metal salt are distributed on the surfaces, cell walls, cell cavities and/or intercellular spaces of the fluffed crack of the wood bundle and exist in the form of complex.

10. The complexed recombined wood according to claim 9, wherein parenchyma cells and ductal cells in the wood strands are compacted.

Technical Field

The invention relates to the technical field of wood processing, in particular to a complex wood bundle, a complex recombined wood and a preparation method thereof.

Background

China is the world with the most abundant fast-growing forest resources, and the fast-growing forest wood is used for producing high-performance wood-based composite materials to make up for the shortage of high-quality wood supply in China, so that the method is an important industrial problem in the forestry industry in China. The recombined wood not only improves and enhances the physical and mechanical properties of the fast-growing forest wood, but also endows the fast-growing forest wood with new functions of hydrophobicity, flame retardance, corrosion resistance, mildew resistance, termite resistance and the like, is one of effective ways for using the fast-growing forest wood resources in small size and using inferior wood in high quality, and is one of the main development directions for efficiently utilizing the fast-growing forest resources in China in the future.

The main problems of wire jumping, deformation, cracking and high water absorption thickness expansion rate of the current recombined wood products are that the wire jumping, deformation or cracking are caused by the recovery of compression deformation and the internal stress generated by cell wall drying shrinkage and wet swelling; in addition, in the directional recombination processing process, polyphenol drift has a great influence on the gluing performance of the phenolic resin, and is also one of the problems of wire jumping, cracking, degumming and the like in some trees with higher polyphenol content such as eucalyptus, casuarina equisetifolia, sumac and the like; in the directional recombination processing process, polyphenol drift has great influence on the gluing performance of the phenolic resin, and is also one of the problems of wire jumping, cracking, degumming and the like in some woods such as eucalyptus, casuarina equisetifolia, sumac and other trees with higher polyphenol content; other species with lower polyphenol content, such as poplar, willow, etc., usually have lighter color. In order to solve the problems of the recombined wood, the wood beams are mainly treated by heat treatment (commonly called carbonization) at present. The heat treatment can pyrolyze hemicellulose and partial cellulose, reduce the number of hydroxyl groups in the wood, improve the dimensional stability and the anti-biological aging performance, and change the color of lignin under the action of damp heat so as to change the color of wood bundles. But the strength of the recombined wood can be reduced by heat treatment, and the mechanical strength of the recombined wood prepared by the wood beam treated at the temperature of 140-200 ℃ is reduced by about 20-70 percent; meanwhile, the heat-treated recombined wood has uncomfortable gum smell, and waste liquid and waste gas are generated in the heat treatment process to cause certain environmental pollution.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides the complex wood bundle, the complex reconstituted wood and the preparation method thereof, solves the problems that the reconstituted wood in the prior art is easy to have wire jumping, deformation, cracking and the like, and keeps better mechanical properties.

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

in one aspect, the present invention provides a method for preparing a bundle of strands of complexed wood, comprising:

step 1: preparing a proper amount of wood bundles;

step 2: introducing plant polyphenol into wood bundle to obtain polyphenol wood bundle;

and step 3: introducing metal salt into the polyphenol wood bundles to obtain polyphenol metal salt wood bundles;

and 4, step 4: and drying the polyphenol metal salt wood bundles to obtain the complex wood bundles.

Further, the step 1 specifically comprises:

11) sawing the log into wood sections with certain length;

12) rotary cutting or slicing the wood sections into veneers with certain thickness;

13) untwining the single boards to form wood bundles;

14) drying the wood beam until the water content is 6-30%.

Further, the step 2 is as follows:

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

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

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

Further, the concentration of the plant polyphenol water solution is 1.0-25.0 g/L, the average molecular weight is 170-50000, and the plant polyphenol water solution is 1-40 polymers; the wood bundle is soaked in the plant polyphenol water solution for 10min to 48h at the soaking temperature of 0 to 80 ℃, and the soaking method is normal pressure, pressurization or pressurization after vacuum pumping; the plant polyphenol is one or more of tannin extract, tannin, tannic acid, terminal food acid, and charred terminal food acid.

Soaking wood bundles in a polyphenol solution, gradually swelling the cell walls of the wood bundles under the action of water, and gradually introducing the plant polyphenol into the surfaces, cell walls, cell cavities and/or cell gaps of defibering cracks of the wood bundles until a preset soaking amount is reached; and taking out the wood bundles, placing the wood bundles in a drying kiln or air to gradually evaporate water in the wood, increasing the concentration of the plant polyphenol in the cells, beginning to precipitate when the concentration reaches an isoelectric point, and solidifying the plant polyphenol in the wood bundles under the action of hydrogen bonds and/or hydrophobic bonds to form the polyphenol wood bundles.

Further, the step 3 is:

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

32) immersing the polyphenol wood bunch in a metal salt aqueous solution.

Further, the concentration of the metal salt water solution is 0.3 g/L-30.0 g/L; the wood bundle 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 normal pressure, pressurization or pressurization after vacuum pumping; the metal salt is one or more of iron salt, copper salt, aluminum salt, titanium salt, calcium salt, molybdenum salt, tungsten salt, chromium salt, magnesium salt, potassium salt and double salts thereof.

Soaking the prepared polyphenol wood bundles in a metal salt solution, wherein the metal salt solution is gradually introduced into the surfaces, cell walls, cell cavities and/or cell gaps of defibering cracks of the wood bundles until a preset impregnation amount is reached; in the process, the polyphenol and the metal ions are complexed into polyphenol-metal ion complexes under the action of water and air, the wood bundle is taken out and placed in a drying kiln or air, and the water in the wood bundle is gradually evaporated, so that the wood bundle, the plant polyphenol and the metal ions form a whole.

Furthermore, the wood bundle contains 0.3-15% of plant polyphenol by weight and 0.1-12% of metal salt by weight, and the plant polyphenol and the metal salt are distributed on the surfaces of the fluffed cracks, cell walls, cell cavities and intercellular spaces of the wood bundle and exist in the form of complex.

The complex wood beam comprises wood beams, plant polyphenol and metal salt, wherein the plant polyphenol is fixed in the wood beams through the action of multi-point hydrogen bonds and/or multi-point hydrophobic bonds with polysaccharides such as cellulose and hemicellulose of the wood beam components, and the polyphenol and metal ions are complexed into a polyphenol-metal ion complex, so that the wood beams, the plant polyphenol and the metal ions form a whole. The hydrogen bonds are mainly generated by the combination of phenolic hydroxyl groups in polyphenol with hydroxyl groups and carbonyl groups in wood bundle cellulose and hemicellulose; the hydrophobic bond is mainly generated by the combination of the benzene ring in the polyphenol and the benzene ring in the lignin in the wood beam; the complexation is mainly generated by chelating hydroxyl of ortho diphenol in the plant polyphenol with metal ions; in addition, ions of boron and copper can be fixed in the recombined wood through complexation, so that the effects of mildew prevention and corrosion prevention can be achieved.

On the other hand, the invention also provides a preparation method of the complex recombined wood, which takes the complex wood bundles as raw materials and comprises the following steps:

step 1: sizing

Impregnating phenolic resin with the molecular weight of 800-2500 or urea-formaldehyde resin with the molecular weight of 600-3000 into the complex wood beam by adopting a gum dipping mode or coating the surface of the complex wood beam by adopting a roll coating mode, wherein the gum application amount is 8-30%;

step 2: drying

Drying the impregnated complex wood bundles in a drying kiln at the drying temperature of 45-75 ℃ and controlling the drying water content at 10-16%;

and step 3: assembly

Assembling the dried complex wood bundles according to the same grain to form a complex recombined wood plate blank;

and 4, step 4: glue synthetic type

Feeding the recombined wood slab into a cold press, and performing cold pressing to prepare a complex recombined wood square stock at the pressure of 30-100MPa and the cold pressing temperature of normal temperature; sending the mixture into a curing channel for curing, wherein the curing temperature is 135-155 ℃, and the curing time is 8-12 h;

or sending the recombined wood board blank into a hot press, and adopting a cold-in and cold-out process, wherein the hot pressure is 6-10MPa, the hot-pressing temperature is 135-.

On the other hand, the invention also provides a complexing restructured wood which is formed by stacking a plurality of layers of complexing wood bundles according to the grain, wherein an adhesive, the phenolic resin or the urea-formaldehyde resin is arranged between each layer of complexing wood bundle; the complex wood bundle contains 0.3-15 wt% of plant polyphenol and 0.1-12 wt% of metal salt, and the plant polyphenol and the metal salt are distributed on the surfaces, cell walls, cell cavities and/or intercellular spaces of the fluffed crack of the wood bundle and exist in the form of complex.

Furthermore, the parenchyma cells and duct cells in the wood beam are compressed and compacted.

The existing research considers that the recombinant wood is cracked due to a plurality of reasons, wherein the most important factor is that polysaccharides (cellulose, hemicellulose and the like) in wood bundles absorb or release water in the processes of moisture absorption and desorption to cause the wood bundles to expand or contract, so that the size of the recombinant wood is unstable and the recombinant wood is cracked.

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

according to the invention, plant polyphenol and metal salt are introduced into the cell walls of the wood bundles, phenolic hydroxyl groups of the plant polyphenol are combined with hydroxyl groups of cellulose and hemicellulose, and meanwhile, ortho phenolic hydroxyl groups are complexed with metal ions to crosslink adjacent molecular chains of the cellulose/hemicellulose into a net structure, just as if a plurality of supports are supported on the molecular chains of the cellulose/hemicellulose, 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 and the hydroxyl groups in wood bundles are combined to form multi-point hydrogen bonds) and coordination bonds (the ortho hydroxyl groups on the plant polyphenol phenolic rings and the metal salts are complexed to form coordination bonds) are formed in the cellulose skeleton. Since the sacrificial bond energy is smaller than the covalent bond (covalent bond network is formed between cellulose, hemicellulose, lignin and phenolic resin), the sacrificial bond is broken in preference to the covalent bond when the wood strand is subjected to internal stress or external force. The dynamic action of the continuous breakage and reconstruction of the sacrificial bonds dissipates a large amount of energy in a wood beam 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 reconstituted wood.

Firstly, introducing plant polyphenol into wood bundles to swell the wood bundles; then introducing metal salt into the wood beam, combining plant polyphenol with cellulose and hemicellulose in the wood beam to form a multi-point hydrogen bond, complexing the plant polyphenol with the metal salt, and combining the cellulose-plant polyphenol-metal salt into a whole just like forming a plurality of bracket supports in a cellulose skeleton molecule; then, accompanied by evaporation and oxidation reaction of moisture, the "cellulose-plant polyphenol-metal salt" is further cross-linked and oxidized, finally forming a complex wood bundle. The dynamic multi-sacrifice bond network structure of the cellulose-plant polyphenol-metal salt supports cellulose and/or hemicellulose, so that the expansion or contraction is reduced or even not generated when the cellulose and/or hemicellulose absorbs moisture or desorbs, and simultaneously, the dynamic action of continuous fracture and reconstruction of sacrifice bonds dissipates a large amount of energy in a recombined wood system, eliminates or weakens the internal stress, protects the integrity of a cellulose skeleton covalent bond network, and solves the problem that the recombined wood is easy to crack from the molecular level.

The method solves the problems that the recombined wood is easy to have wire jumping, deformation, cracking, high water absorption thickness expansion rate and the like in the prior art, and keeps better mechanical property.

Drawings

FIG. 1 is a structural diagram of a cellulose molecular chain of a polyphenol wood strand according to the present invention;

FIG. 2 is a structural diagram of cellulose molecular chains of the complex wood strands according to the present invention;

FIG. 3 is a view showing bundles of eucalyptus wood before and after treatment in example 1 of the present invention;

FIG. 4 is a drawing showing the bundle of strands of complexed wood immersed in boiling water in accordance with example 1 of the present invention;

FIG. 5 is a graph of reconstituted eucalyptus wood after and before intermediate treatment in example 2 of the present invention;

FIG. 6 is a view showing a reconstituted eucalyptus tree according to example 4 of the present invention immersed in boiled water;

FIG. 7 is a graph of an untreated eucalyptus reconstituted wood of example 4 of the present invention after a field decay test;

fig. 8 is a diagram of the complex eucalyptus reconstituted wood subjected to a field decay test in example 4 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.