阅读说明：本技术 一种络合木质材料的制备方法 (Preparation method of complex wood material ) 是由 余养伦 吕斌 张耀明 于文吉 于 2019-09-20 设计创作，主要内容包括：本发明涉及一种络合木质材料的制备方法,属于木材加工技术领域。上述络合木质材料的制备方法包括：步骤1：准备多酚含量大于/等于质量比0.3％的木质材料；步骤2：向上述木质材料中导入金属盐,得到多酚金属盐木质材料；步骤3：干燥多酚金属盐木质材料,得到络合木质材料。本发明利用木质材料中多酚物质,在木质材料中引入金属离子,通过氢键、配位键形成了“纤维素-植物多酚-金属盐”动态多重牺牲键网络结构,将金属离子原位固定在木质细胞的细胞腔、细胞壁和细胞间隙中,以达到消除或削弱木质材料内应力,减少开裂,改善尺寸稳定性、渗透性能、防腐、防霉和改变颜色等作用。(The invention relates to a preparation method of a complex wood material, and belongs to the technical field of wood processing. The preparation method of the complex wood material comprises the following steps: step 1: preparing a wood material with polyphenol content of more than or equal to 0.3 percent by mass; step 2: introducing metal salt into the wood material 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. According to the invention, polyphenol substances in the wood material are utilized, metal ions are introduced into the wood material, a dynamic multiple sacrificial bond network structure of cellulose-plant polyphenol-metal salt is formed through hydrogen bonds and coordination bonds, and the metal ions are fixed in situ in cell cavities, cell walls and cell gaps of wood cells, so that the effects of eliminating or weakening the internal stress of the wood material, reducing cracking, improving the dimensional stability and the permeability, preventing corrosion and mildew, changing the color and the like are achieved.)

1. A method of making a complexed wood material, comprising:

step 1: selecting wood with polyphenol content of more than or equal to 0.3 percent by mass, and pretreating to obtain a wood material;

step 2: introducing metal salt into the wood material 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.

2. The method of making the complexed wood-based material of claim 1 wherein the wood is one or more of eucalyptus, oak, beech, catalpa, mahogany, pterocarpus marsupium, and larch.

3. The method of claim 1, wherein the pre-treatment in step 1 is one or more of wood processing into log, sawn timber, laminated timber, cross-laminated timber, laminated veneer lumber, oriented strand board, laminated wood, plywood, reconstituted wood, particle board, fiber board, plywood, veneer, wood beam, wood shavings, and fiber.

4. The method of making a complexed wood-based material according to claim 1 wherein said step 2 is:

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

22) the above wood material is immersed in a metal salt aqueous solution to introduce metal ions into the cell cavities, cell walls or intercellular spaces.

5. The method of making a complexed wood-based material according to claim 4 wherein the concentration of the aqueous metal salt solution is from 0.3g/L to 300 g/L.

6. The method of preparing a complexed wooden material according to claim 5, wherein the wooden material is impregnated in the aqueous solution of the metal salt for a period of time ranging from 10min to 180 days at a temperature ranging from 0 ℃ to 80 ℃.

7. The method of claim 6, wherein the impregnation is performed under atmospheric pressure, under pressure, or under vacuum followed by pressurization.

8. The method of claim 4, wherein 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.

9. The method of claim 1, wherein the pH of the aqueous solution of the metal salt in step 2 is 3.5-4.5.

10. The method of claim 1, wherein in the step 3, the absolute moisture content of the dried polyphenolic metal salt wood material is 25% to 50%, and then the oxygen content in the air is adjusted to 22% to 50% until the absolute moisture content of the polyphenolic metal salt wood material is 6% to 12%.

Technical Field

The invention relates to the technical field of wood processing, in particular to a preparation method of a complex wood material.

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 wood material cannot meet the increasing market demand in the fields of products and application due to the inherent properties of wood, and the wood functional improvement technology aims at improving the quality of the wood material, endows the wood material with new performance and expanding the application range of the wood material, and becomes an important component part of sustainable development of social economy in China.

Wood products and wood materials have outstanding properties such as environmental properties-visual, tactile, auditory, olfactory and regulatory properties of wood, material properties-processability, 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.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a preparation method of a complex wood material, which utilizes polyphenol substances in the wood material, introduces metal ions into the wood material, and forms a dynamic multiple sacrificial bond network structure of cellulose-plant polyphenol-metal salt through hydrogen bonds and coordination bonds, and has the advantages of cracking reduction, even no cracking, stable size and the like.

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

the invention provides a preparation method of a complex wood material, which comprises the following steps:

step 1: selecting wood with the polyphenol content of more than or equal to 0.3 percent by mass, and carrying out pretreatment to obtain a wood material;

step 2: introducing metal salt into the wood material 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.

Preferably, the wood is one or more of eucalyptus, oak, beech, catalpa, peach blossom, pterocarpus marsupium (pyrus ussuriensis) and larch.

Further, in step 1, the pretreatment is to treat the wood into one or more combinations of raw wood, sawn wood, laminated wood, cross-laminated wood, laminated veneer lumber, oriented strand board, laminated wood, plywood, reconstituted wood, particle board, fiber board, plywood, veneer, wood beam, wood shavings and fibers.

Further, the step 2 is as follows:

21) dissolving metal salt in the aqueous solution, and stirring uniformly to form a metal salt aqueous solution;

22) the polyphenol wood material is immersed in a metal salt aqueous solution to introduce metal ions into the cell cavities, cell walls or intercellular spaces.

Further, the concentration of the metal salt water solution is 0.3 g/L-300 g/L; the wood material is soaked in the metal salt water solution for 10min-180 days at the soaking temperature of 0-80 ℃, and the soaking method is normal pressure, pressurization or pressurization after vacuum pumping.

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.

Preferably, the absolute water content of the dried polyphenol metal salt wood is 25-50%, and then the oxygen content in the air is adjusted to 22-50% until the absolute water content of the polyphenol metal salt wood is 6-12%.

The prior researches have considered that the cracking of the wood material is caused by a plurality of reasons, wherein the main factor is that polysaccharides (cellulose and hemicellulose) in the wood material absorb or release water in the processes of moisture absorption and desorption to cause the material to expand or shrink, so that the size of the wood material is unstable and the cracking is caused, and the principle is shown in figure 1.

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

according to the invention, phenolic hydroxyl groups of plant polyphenol are combined with hydroxyl groups of cellulose and hemicellulose, and meanwhile, ortho-position phenolic hydroxyl groups are complexed with metal ions, so that molecular chains of adjacent cellulose/hemicellulose are crosslinked into a net structure, as if a plurality of supports are supported on the molecular chains of the cellulose/hemicellulose, steric hindrance is formed between the molecular chains of the cellulose/hemicellulose, and the size of the net structure is reduced or even does not expand or shrink when moisture absorption or desorption is carried out; on the basis of the above, a large number of multiple sacrificial bond networks consisting of hydrogen bonds (the plant polyphenol phenolic hydroxyl groups are combined with the hydroxyl groups in the wood 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 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 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 system, eliminates or weakens internal stress, and protects the integrity of a cellulose skeleton covalent bond network. In addition, water complexes the cellulose, tannins and metal salts in wood to form various forms of bound water, which contributes to density in the wood. This provides a new approach to the problem of wood cracking.

The method comprises the steps of firstly introducing metal salt into wood containing plant polyphenol, complexing the plant polyphenol with the metal salt, and combining cellulose-plant polyphenol-metal salt into a whole by utilizing multipoint hydrogen bond combination formed between the plant polyphenol and cellulose and hemicellulose in the wood, just as if a plurality of bracket supports are formed in cellulose skeleton molecules, and steric hindrance is formed between cellulose/hemicellulose molecular chains; then, accompanied by evaporation and oxidation reactions of water, the "cellulose-plant polyphenol-metal salt" is further cross-linked and oxidized, finally forming a complex woody material. The dynamic multiple sacrificial bond network structure of cellulose-plant polyphenol-metal salt forms steric hindrance between cellulose/hemicellulose molecular chains, so that the dynamic effect of continuous fracture and reconstruction of the sacrificial bonds reduces or even does not generate expansion or contraction when absorbing or desorbing moisture, dissipates a large amount of energy in a wood recombination material system, eliminates or weakens internal stress, protects the integrity of a cellulose skeleton covalent bond network, solves the problem of easy cracking of wood from a molecular level, and has the principle shown in figure 2.

In addition, the cellulose-plant polyphenol-metal salt formed in the cell walls, cell cavities and intercellular spaces of the wood not only changes the visual, tactile, auditory, olfactory and other characteristics of the wood, but also endows the wood with certain odor removal characteristic, and improves the temperature and humidity regulation performance, heat conduction, electric conduction, biological resistance, durability and other performances of the wood.

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 comparison of the situation of the untreated eucalyptus and eucalyptus complex wood in example 1 of the present invention;

FIG. 4 is a graph showing a comparison between oak sawn timber and a oak complex in example 2 of the present invention;

FIG. 5 is a graph showing the chordwise and radial shrinkage rates at different absolute moisture contents before and after oak treatment in example 2 of the present invention;

FIG. 6 is a comparison graph of Pterocarpus marsupium (Reynaudia) Rehd and Pterocarpus marsupium (Reynaudia) Rehd of example 3 of the present invention;

fig. 7 is a picture of complexed recombined poplar in embodiment 4 of the 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.