阅读说明：本技术 一种环保高强木质纤维基复合材料的制备方法 (Preparation method of environment-friendly high-strength wood fiber-based composite material ) 是由 严玉涛 翁铭渝 吴杰 金春德 王喆 于 2020-12-25 设计创作，主要内容包括：本发明公开了一种环保高强木质纤维基复合材料的制备方法,所述方法包括以下步骤：步骤一：对木质纤维预处理；步骤二：配制多氨基化合物水或乙醇溶液以及交联剂溶液；步骤三：对所述步骤一中得到的经过预处理的木质纤维施胶；步骤四：将步骤三中施胶后的木质纤维铺装及热压成型得到木质纤维基复合材料。本发明通过纤维预处理,环保型多氨基化合物配方筛选以及工艺条件优化,热压制备的纤维板具有无醛、高强、耐水等特点,其物理力学性能均达到国家标准中关于普通型中密度纤维板的要求,能很好的满足行业的要求,具有较好的应用前景。(The invention discloses a preparation method of an environment-friendly high-strength wood fiber-based composite material, which comprises the following steps: the method comprises the following steps: pretreating wood fibers; step two: preparing water or ethanol solution of polyamino compound and cross-linking agent solution; step three: sizing the pretreated wood fibers obtained in the first step; step four: and (3) paving the wood fiber after glue application in the step three, and performing hot press molding to obtain the wood fiber-based composite material. According to the invention, through fiber pretreatment, formula screening of an environment-friendly polyamino compound and optimization of process conditions, the fiberboard prepared by hot pressing has the characteristics of no aldehyde, high strength, water resistance and the like, the physical and mechanical properties of the fiberboard meet the requirements of common medium-density fiberboards in national standards, the requirements of the industry can be well met, and the fiberboard has a better application prospect.)

1. The preparation method of the environment-friendly high-strength wood fiber-based composite material is characterized by comprising the following steps of:

the method comprises the following steps: pretreating wood fibers;

step two: preparing water or ethanol solution of polyamino compound and cross-linking agent solution;

step three: sizing the pretreated wood fiber obtained in the step one and spraying a proper amount of a cross-linking agent;

step four: and (3) paving the wood fiber after glue application in the step three, and performing hot press molding to obtain the wood fiber-based composite material.

2. The method for preparing the environment-friendly high-strength wood fiber-based composite material as claimed in claim 1, wherein the wood fibers in the first step include wood fibers, bamboo fibers, palm fibers and hemp fibers, wherein the wood fibers are obtained from wood fibers obtained by thermally cooking, grinding and drying in the process of preparing the fiberboard; the bamboo fibers, the palm fibers and the hemp fibers are all original fibers and are not chemically treated.

3. The method for preparing the environment-friendly high-strength wood fiber-based composite material as claimed in claim 2, wherein the first step specifically comprises:

wood fiber pretreatment: adding wood fiber into distilled water, stirring uniformly, adding the uniformly stirred mixed system into a colloid grinder, grinding for 1-6h, and filtering out water by using a 100-mesh screen, wherein the water content is controlled at 100%;

bamboo fiber, palm fiber and hemp fiber pretreatment: adding bamboo fiber, palm fiber and hemp fiber into 1% sodium hydroxide solution, boiling in boiling water, and washing with clear water to neutrality.

4. The method for preparing the environment-friendly high-strength wood fiber-based composite material as claimed in claim 3, wherein the step two of preparing the polyamino compound water or ethanol solution is specifically as follows: adding polyamino compounds with different types, different molecular weights and different masses into deionized water or ethanol solution, dissolving, and stirring uniformly to prepare solutions with different concentrations.

5. The method for preparing the environment-friendly high-strength wood fiber-based composite material as claimed in claim 4, wherein the polyamino compound comprises polyethyleneimine, chitosan and polyamidoamine dendrimer (PAMAM), the polyethyleneimine has a molecular weight of 1800, 10000 and 70000, the chitosan comprises chitosan with a viscosity of less than 200mPa.s, chitosan with a viscosity of 200-400mPa.s and chitosan with a viscosity of more than 400mPa.s, the polyamidoamine dendrimer comprises 0.5 generation, 1 generation and 2 generation, and the different masses are 2.5%, 5% and 7.5% of the weight of the absolutely dry wood fiber.

6. The method for preparing environment-friendly high-strength wood fiber-based composite material as claimed in claim 5, wherein the cross-linking agent in the second step comprises: dialdehydes and glycidyl ethers.

7. The method for preparing the environment-friendly high-strength wood fiber-based composite material as claimed in claim 6, wherein the cross-linking agent in the second step is: glyoxal, glutaraldehyde and ethylene glycol diglycidyl ether.

8. The preparation method of the environment-friendly high-strength wood fiber-based composite material according to claim 6 or 7, wherein the third step is specifically: the prepared polyamino compound solution is filled into a high-pressure spray can and sprayed on the surface of the wood fiber, then a predetermined amount of cross-linking agent solution is sprayed on the surface of the wood fiber, the cross-linking agent solution is uniformly mixed through a glue mixer, the mixture is placed in the air for a period of time, the water content reaches 100%, and the predetermined amount refers to 1%, 2.5% and 5% relative to the weight of the absolutely dry wood fiber.

9. The method for preparing the environment-friendly high-strength wood fiber-based composite material as claimed in claim 8, wherein the wood fibers uniformly mixed in the third step are uniformly paved into a plate blank, and then hot-pressed for 6-12min at the temperature of 160-220 ℃ and under the pressure of 1-2.5MPa to obtain the wood fiber-based composite material.

10. A lignocellulosic-based composite material, wherein the lignocellulosic-based composite material is prepared by the method of any one of claims 1 to 9.

Technical Field

The invention belongs to the technical field of wood fiber-based composite materials, and particularly relates to a preparation method of an environment-friendly high-strength wood fiber-based composite material.

Background

The wood fiber is a natural renewable biomass resource (including wood fiber, bamboo fiber, cotton-flax fiber, palm fiber and the like) with rich sources, low price and high specific strength, and the wood fiber-based composite material prepared by taking the wood fiber as a raw material is widely applied to the industries of buildings, decorations, automobiles, home furnishings and furniture. In order to ensure the mechanical property of the wood fiber composite material, the use of an adhesive is often involved in the preparation process of the wood fiber composite material, however, the currently used adhesive is mainly urea-formaldehyde resin or melamine modified urea-formaldehyde resin, and the problem of formaldehyde release exists in the preparation and use processes, so that the pollution to workshops and living environments is brought, and the health of people is harmed.

In order to reduce or solve the formaldehyde emission problem of adhesives, a variety of natural biomass high molecular compounds such as soybean (isolated) protein, starch, tannin, lignin and the like are utilized to partially or completely replace formaldehyde to prepare low-formaldehyde or formaldehyde-free adhesives. Although the methods can partially or completely solve the problem of formaldehyde release, the synthesis or modification process of the adhesive is complex, and the composite material prepared by the adhesive has low mechanical strength and poor water resistance, so that the use of the adhesive is limited. Therefore, the development of the wood fiber composite material with environmental protection, high bonding strength and water resistance has important practical significance.

Disclosure of Invention

In order to solve the problems, the invention provides a preparation method of an environment-friendly high-strength wood fiber-based composite material, and the fiber board prepared by hot pressing has the characteristics of no aldehyde, high strength, water resistance and the like through fiber pretreatment, formula screening of an environment-friendly polyamino compound and optimization of process conditions, and the physical and mechanical properties of the fiber board reach the requirements of the common medium-density fiber board in national standards, can well meet the requirements of the industry, and has better application prospects.

The technical solution to achieve the above object is as follows:

a preparation method of an environment-friendly high-strength wood fiber-based composite material comprises the following steps:

the method comprises the following steps: pretreatment of wood fibers

The wood fiber comprises wood fiber, bamboo fiber, palm fiber, hemp fiber and the like. Wherein the wood fiber is obtained from wood fiber obtained by thermal cooking, grinding and drying in the preparation process of the fiberboard; the bamboo fibers, palm fibers and hemp fibers are all original fibers and are not chemically treated.

Wood fiber pretreatment: weighing 100g of wood fiber, adding the wood fiber into 4L of distilled water, uniformly stirring, adding the mixed system into a colloid grinder, and grinding for 1-6 h; filtering with 100 mesh screen to remove water, and controlling water content at 100%.

Bamboo fiber, palm fiber and hemp fiber pretreatment: weighing 100g of fiber, adding the fiber into a 1% sodium hydroxide solution, boiling in boiling water for 1h, and then washing with clear water to be neutral for later use.

Step two: preparation of polyamino compound water or alcohol solution and cross-linking agent solution

Adding polyamino compounds with different types, different molecular weights and different masses into deionized water or ethanol solution, dissolving, stirring uniformly, and preparing into solutions with different concentrations for later use.

The polyamino compound comprises polyethyleneimine, chitosan and polyamide-amine dendrimer (PAMAM); the molecular weight of the polyethyleneimine is 1800, 10000 and 70000 respectively; chitosan includes low viscosity (<200mpa.s), medium viscosity (200-; PAMAM includes generations 0.5, 1 and 2;

the different masses are 2.5%, 5%, 7.5% by weight of the oven dry wood fibres.

The cross-linking agent comprises a dialdehyde and a glycidyl ether, preferably glyoxal, glutaraldehyde and ethylene glycol diglycidyl ether.

Step three: sizing for wood fiber

The prepared polyamino compound solution is filled into a high-pressure spray can and sprayed on the surface of the fiber; then spraying a certain amount of cross-linking agent solution on the surface of the wood fiber, uniformly stirring by a glue mixer, and placing in the air for a period of time to ensure that the water content reaches 100 percent.

The stated amounts refer to 1%, 2.5%, 5% relative to the weight of the oven-dried wood fibres.

Step four: paving and hot press molding of wood fiber-based composite material

Uniformly paving the uniformly mixed wood fibers in the third step into a plate blank, and then carrying out hot pressing for 6-12min at the temperature of 160-.

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

(1) the adhesive (amino compound), the cross-linking agent and the related solvent used for preparing the wood fiber-based composite material are nontoxic and environment-friendly reagents, and the prepared composite material is a real environment-friendly product;

(2) the grinding, step-by-step high-pressure spraying and hot-compacting petrochemical technologies adopted in the preparation process of the wood fiber composite material are common and easy-to-operate technologies, so that the preparation method has the advantages of simple preparation process, safety, strong operability and the like, is suitable for large-scale industrial application, and has strong practicability;

(3) the wood fiber-based composite material prepared by the invention has excellent mechanical strength and water resistance, and meets or even exceeds the minimum index of national standard on the performance requirements of common fiber boards and shaving boards;

(4) the polyamino compound adopted by the invention has good universality as an adhesive, and can be suitable for a plurality of wood fibers such as wood fibers, bamboo fibers, hemp fibers, palm fibers and the like.

Drawings

FIG. 1 is a flow chart of the preparation of a lignocellulosic composite based on polyamino compound gluing according to the invention.

Fig. 2 is a cross-sectional SEM image of different lignocellulosic-based composites.

Detailed Description

The following examples are provided to more clearly illustrate the technical solutions of the present invention, but are not intended to limit the scope of the present invention.

Example 1:

a preparation method of a high-strength environment-friendly wood fiber-based composite material comprises the following steps:

(1) pretreatment of wood fibers

100g of wood fiber is weighed and added into 4L of distilled water, the mixture is stirred evenly, and then the mixed system is added into a colloid grinder to be ground for 2 hours.

(2) Preparation of polyamino compound water or solution adhesive and cross-linking agent solution

Adding 2.5g of polyethyleneimine with the molecular weight of 1800 into 30g of deionized water, and uniformly stirring to prepare a water solution; 2.5g of glutaraldehyde is added to 10g of absolute ethanol to prepare a glutaraldehyde-ethanol solution for later use.

(3) Sizing for wood fiber

Filling the prepared polyethyleneimine solution into a high-pressure spray can, and spraying the polyethyleneimine solution on the surface of the fiber; and then spraying the glutaraldehyde solution on the surface of the wood fiber, uniformly stirring the solution by a glue mixer, and placing the solution in the air for a period of time to ensure that the water content reaches 100 percent.

(4) Paving and hot press molding of wood fiber-based composite material

Uniformly paving the uniformly mixed wood fibers in the step (3) into a plate blank, and then carrying out hot pressing for 10min at 220 ℃ and under the pressure of 1MPa to obtain a wood fiber-based composite material, wherein the microscopic morphology of the wood fiber-based composite material is shown in figure 2, and figure 2 is a cross section SEM (scanning Electron microscope) diagram of different wood fiber-based composite materials, wherein (a) the pure wood fiber composite material; (b) a wood fiber composite material of polyethylene imine glue joint; (c) a glutaraldehyde cross-linked polyethyleneimine-wood fiber composite; (d) and after the fiber is ground, the glutaraldehyde crosslinked polyethyleneimine-wood fiber composite material.

Performance detection

The physical and mechanical properties of the prepared board are detected according to the national standard GB/T17657-2013 artificial board and veneer artificial board physical and chemical property test method. The density of the lignocellulosic composite obtained in example 1 was 0.78g/cm³The static bending strength and the modulus value are respectively 32.41MPa and 2900MPa, the internal bonding strength is 1.15MPa, and the water absorption thickness expansion rate is 40%, which just meet the minimum requirements of the standard of GBT 11718-2009 medium density fiberboard (the static bending strength is 27MPa, the elastic modulus is 2700MPa, the internal bonding strength is 0.6MPa, and the water absorption thickness expansion rate in 24 hours is less than 45%).

Example 2:

(1) pretreatment of wood fibers

100g of wood fiber is weighed and added into 4L of distilled water, the mixture is stirred evenly, and then the mixed system is added into a colloid grinder to be ground for 1 hour.

(2) Preparation of polyamino compound aqueous solution adhesive and cross-linking agent solution

Adding 2.5g of polyethyleneimine with the molecular weight of 70000 into 30g of deionized water, and uniformly stirring to prepare an aqueous solution; 2.5g of glutaraldehyde is added to 10g of absolute ethanol to prepare a glutaraldehyde-ethanol solution for later use.

(3) Sizing for wood fiber

Filling the prepared polyethyleneimine solution into a high-pressure spray can, and spraying the polyethyleneimine solution on the surface of the fiber; and then spraying the glutaraldehyde solution on the surface of the wood fiber, uniformly stirring the solution by a glue mixer, and placing the solution in the air for a period of time to ensure that the water content reaches 100 percent.

(4) Paving and hot press molding of wood fiber-based composite material

Uniformly paving the uniformly mixed wood fibers in the step (3) into a plate blank, and then carrying out hot pressing for 10min under the conditions of 200 ℃ and 2MPa pressure to obtain the wood fiber-based composite material.

Performance detection

The physical and mechanical properties of the prepared board are detected according to the national standard GB/T17657-2013 artificial board and veneer artificial board physical and chemical property test method. In example 2The density of the obtained wood fiber-based composite material is 0.80g/cm³The static bending strength and the modulus value are respectively 43.26MPa and 3576MPa, the internal bonding strength is 1.48MPa, and the water absorption thickness expansion rate is 29.5 percent, so that the minimum requirement of the standard of GBT 11718-2009 medium density fiberboard is met.

Example 3:

(1) pretreatment of wood fibers

100g of wood fiber is weighed and added into 4L of distilled water, the mixture is stirred evenly, and then the mixed system is added into a colloid grinder to be ground for 2 hours.

(2) Preparation of polyamino compound aqueous solution adhesive and cross-linking agent solution

Adding 5g of polyethyleneimine with the molecular weight of 10000 into 30g of deionized water, and uniformly stirring to prepare an aqueous solution; 2.5g of glutaraldehyde is added to 10g of absolute ethanol to prepare a glutaraldehyde-ethanol solution for later use.

(3) Sizing for wood fiber

Filling the prepared polyethyleneimine solution into a high-pressure spray can, and spraying the polyethyleneimine solution on the surface of the fiber; and then spraying the glutaraldehyde solution on the surface of the wood fiber, uniformly stirring the solution by a glue mixer, and placing the solution in the air for a period of time to ensure that the water content reaches 100 percent.

(4) Paving and hot press molding of wood fiber-based composite material

Uniformly paving the uniformly mixed wood fibers in the step (3) into a plate blank, and then carrying out hot pressing for 12min under the conditions of 180 ℃ and 2MPa pressure to obtain the wood fiber-based composite material.

Performance detection

The physical and mechanical properties of the prepared board are detected according to the national standard GB/T17657-2013 artificial board and veneer artificial board physical and chemical property test method. The density of the lignocellulosic composite obtained in example 3 was 0.88g/cm³The static bending strength and the modulus value are respectively 58.60MPa and 5800MPa, the internal bonding strength is 2.16MPa, and the minimum requirements (static bending strength 38MPa, elastic modulus 3900MPa and internal bonding strength 0.95MPa) of the national standard GB/T31765-2015 high-density fiberboard are far exceeded.

Example 4:

(1) pretreatment of wood fibers

100g of wood fiber is weighed and added into 4L of distilled water, the mixture is stirred evenly, and then the mixed system is added into a colloid grinder to be ground for 4 hours.

(2) Preparation of polyamino compound aqueous solution adhesive and cross-linking agent solution

Adding 5g of polyethyleneimine with the molecular weight of 10000 into 30g of deionized water, and uniformly stirring to prepare an aqueous solution; 5g of glutaraldehyde is added to 10g of absolute ethanol to prepare a glutaraldehyde-ethanol solution for later use.

(3) Sizing for wood fiber

Filling the prepared polyethyleneimine solution into a high-pressure spray can, and spraying the polyethyleneimine solution on the surface of the fiber; and then spraying the glutaraldehyde solution on the surface of the wood fiber, uniformly stirring the solution by a glue mixer, and placing the solution in the air for a period of time to ensure that the water content reaches 100 percent.

(4) Paving and hot press molding of wood fiber-based composite material

Uniformly paving the uniformly mixed wood fibers in the step (3) into a plate blank, and then carrying out hot pressing for 8min under the conditions of 180 ℃ and 1.5MPa pressure to obtain the wood fiber-based composite material.

Performance detection

The physical and mechanical properties of the prepared board are detected according to the national standard GB/T17657-2013 artificial board and veneer artificial board physical and chemical property test method. The density of the lignocellulosic composite obtained in example 4 was 0.88g/cm³The static bending strength and the modulus value are large and respectively 56.60MPa and 5500MPa, which exceed the minimum requirements of the national standard GB/T31765-2015 high-density fiberboard.

Example 5:

(1) pretreatment of bamboo fibers

Adding 100g of bamboo fiber into 1% sodium hydroxide solution, boiling in boiling water for 1h, and washing with clear water to neutrality for later use.

(2) Preparation of polyamino compound aqueous solution adhesive and cross-linking agent

Adding 5g of polyethyleneimine with the molecular weight of 10000 into 30g of deionized water, and uniformly stirring to prepare an aqueous solution; 2.5g of glutaraldehyde is added to 10g of absolute ethanol to prepare a glutaraldehyde-ethanol solution for later use.

(3) Bamboo fiber sizing

Filling the prepared polyethyleneimine solution into a high-pressure spray can, and spraying the polyethyleneimine solution on the surface of the bamboo fiber; and then spraying a glutaraldehyde solution on the surface of the bamboo fiber, uniformly stirring the glutaraldehyde solution by a glue mixer, and placing the bamboo fiber in the air for a period of time to enable the water content to reach 100%.

(4) Paving and hot-press forming of bamboo fiber based composite material

Uniformly paving the uniformly mixed bamboo fibers in the step (3) into a plate blank, and then carrying out hot pressing for 10min under the conditions of 180 ℃ and 2.5MPa pressure to obtain the bamboo fiber-based composite material.

Performance detection

The physical and mechanical properties of the prepared board are detected according to the national standard GB/T17657-2013 artificial board and veneer artificial board physical and chemical property test method. The density of the bamboo fiber-based composite material obtained in example 5 was 0.85g/cm³The static bending strength and the modulus value are large and respectively 60.98MPa and 3886MPa, thereby meeting the minimum requirements of the GB/T31765-2015 high-density fiberboard standard.

Example 6:

(1) pretreatment of palm fibre

Adding 100g of palm fiber into 1% sodium hydroxide solution, boiling in boiling water for 1h, and washing with clear water to neutrality for later use.

(2) Preparation of polyamino compound aqueous solution adhesive and cross-linking agent

Adding 5g of polyethyleneimine with the molecular weight of 10000 into 30g of deionized water, and uniformly stirring to prepare an aqueous solution; 2.5g of glutaraldehyde is added to 10g of absolute ethanol to prepare a glutaraldehyde-ethanol solution for later use.

(3) Sizing palm fiber

Filling the prepared polyethyleneimine solution into a high-pressure spray can, and spraying the polyethyleneimine solution on the surface of the palm fibers; and then spraying a glutaraldehyde solution on the surface of the palm fiber, uniformly stirring the solution by a glue mixer, and placing the mixture in the air for a period of time to ensure that the water content reaches 100 percent.

(4) Paving and hot press molding of palm fiber-based composite material

And (4) uniformly paving the uniformly mixed palm fibers in the step (3) into a plate blank, and then carrying out hot pressing for 10min at the temperature of 180 ℃ and under the pressure of 2.5MPa to obtain the palm fiber-based composite material.

Performance detection

The physical and mechanical properties of the prepared board are detected according to the national standard GB/T17657-2013 artificial board and veneer artificial board physical and chemical property test method. The density of the palm fiber-based composite material obtained in example 6 was 0.80g/cm³The static bending strength and the modulus value are respectively 107.76MPa and 7669MPa, the mechanical properties of the composite material far exceed the minimum requirements of static bending strength (36.00MPa) and elastic modulus (3100MPa) in the national standard GB/T31765-2015 high-density fiberboard, and the board does not use any toxic substance, so the composite material is a high-strength environment-friendly palm fiber-based composite material.

The experimental results of the above embodiments show that the wood fiber-based composite material prepared by the invention has high mechanical properties and good water resistance, and the prepared product is non-toxic and environment-friendly.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.