CN113386234A

CN113386234A - Composite board, wood and manufacturing method thereof

Info

Publication number: CN113386234A
Application number: CN202110677883.XA
Authority: CN
Inventors: 曹一平; 陈杨威; 胡屹鹏
Original assignee: Jianghan University
Current assignee: Jianghan University
Priority date: 2021-06-18
Filing date: 2021-06-18
Publication date: 2021-09-14
Anticipated expiration: 2041-06-18
Also published as: CN113386234B

Abstract

The invention discloses a composite board, wood and a manufacturing method thereof, and belongs to the technical field of wood processing. The wood is prepared by mixing the raw materials and then hot-pressing; the raw materials comprise 70-75% of wood chips, 6-8% of sodium alginate solution, 0.8-1.5% of borate, 0.1-0.3% of pyrogallic acid, 15-20% of acrylamide, 0.1-0.3% of N, N-dimethyl bisacrylamide and 2-3% of ammonium persulfate. The invention also provides a wood manufacturing method, which comprises the steps of S1, adding the wood chips into the sodium alginate solution, and mixing to obtain a first mixed solution; s2, adding borate and pyrogallic acid into the first mixed solution, and continuously stirring to obtain a second mixed solution; s3, adding acrylamide, N, N-dimethyl bisacrylamide and ammonium persulfate into the second mixed solution to obtain a mixture; and S4, filtering and hot-pressing the mixture to obtain wood. The wood has certain strength and can be repaired by self.

Description

Composite board, wood and manufacturing method thereof

Technical Field

The invention relates to the technical field of wood processing, in particular to a composite board, wood and a manufacturing method thereof.

Background

In daily life, wood is widely used as a basic building material in daily life in all aspects of life. The wood is a natural nano composite material, and has the advantages of light weight, high strength and high yield. Although wood is a good building material, wood chips are easily produced during the processing of wood, and are construction wastes, which are difficult to produce, and costly to clean, although wood processing waste is currently prepared and recycled by binding wood chips with phenol resin. However, the composite wood board prepared by the phenolic resin is easy to volatilize formaldehyde and is harmful to human bodies. Therefore, it is necessary to develop a healthy polymer wood without undesirable gas volatilization.

The composite board is prepared by adding the waste residues of the wood chips generated in the wood processing process into phenolic aldehyde and performing high-temperature hot pressing on the mixture. And (4) after cutting, sticking the cut composite board with a plastic board, and then sealing edges with plastic to prepare the composite board. The phenolic aldehyde composite board prepared by the method has low comprehensive cost and is widely applied.

There are also methods for bonding wood chips by modifying the surface chemical bonds of the wood chips, such as by soaking the saw dust in NaOH to soften it to remove lignin, then performing surface carboxylation with TEMPO, carboxyl and Ca²⁺Can generate stronger complexation. Then adding CaCl₂Bonding the carboxylated sawdust together, and finally carrying out hot pressing to form the polymer wood; or adding NaOH into natural wood to remove lignin in the wood, and then performing hot-pressing compaction under a high pressure condition to prepare the high-strength polymer wood.

Conventional phenolic bonded composite panels are made by bonding wood chips with phenolic resin. The composite board core thus contains a significant amount of formaldehyde and is wrapped by the face sheets, which seal the edges of the board. The formaldehyde volatilization speed in the wood board is greatly reduced, so that the composite board can release formaldehyde for a long time, and once the seal of the composite board is damaged, the formaldehyde releasing speed is increased. The composite board is not a healthy building material. In addition, in the process of processing the composite board, formaldehyde is used, which can cause certain harm to the health of workers processing the composite board.

How to avoid using formaldehyde to obtain wood with certain strength is a technical problem which needs to be solved urgently.

Disclosure of Invention

The invention aims to overcome the technical defects, provides a composite board, wood and a manufacturing method thereof, and solves the technical problem of how to obtain wood with certain strength while avoiding using formaldehyde in the prior art.

In order to achieve the technical purpose, the technical scheme of the invention provides wood which is prepared by mixing raw materials and then hot-pressing; the raw materials comprise, by mass, 70-75% of sawdust, 6-8% of sodium alginate solution, 0.8-1.5% of borate, 0.1-0.3% of pyrogallic acid, 15-20% of acrylamide, 0.1-0.3% of N, N-dimethyl bisacrylamide, 2-3% of ammonium persulfate and 100% of total.

Further, the mass concentration of the sodium alginate solution is 1-2%.

Further, the borate is sodium tetraborate.

The invention also provides a manufacturing method of the wood, which comprises the following steps:

s1, adding wood chips into the sodium alginate solution according to the mixture ratio of the raw materials, and mixing to obtain a first mixed solution;

s2, adding borate and pyrogallic acid into the first mixed solution, and continuously stirring to obtain a second mixed solution;

s3, adding acrylamide, N, N-dimethyl bisacrylamide and ammonium persulfate into the second mixed solution to obtain a mixture;

and S4, filtering and hot-pressing the mixture to obtain the wood.

Further, before step S2, the method further includes pre-treating the wood chips, specifically, soaking the wood chips in a sodium hydroxide solution for 3-4 days.

Further, before step S4, the method further comprises refrigerating the mixture at-30 ℃ to 0 ℃.

Further, in step S4, the hot pressing includes pressurizing and then heating.

Further, in step S4, the hot pressing conditions are: the hot pressing temperature is 60-100 ℃, and the hot pressing strength is 30-50 MPa.

Further, in step S1, the first mixed solution is obtained by mixing for 15 to 20 min.

The invention also provides a composite board which comprises the wood or the wood prepared by the manufacturing method.

Compared with the prior art, the invention has the beneficial effects that: according to the wood provided by the invention, sodium alginate can generate hydrogen bond action with hydroxyl on wood chips to enable the wood chips to be better dispersed, acrylamide and N, N-dimethyl bisacrylamide generate polymerization reaction under the action of ammonium persulfate to generate polyacrylamide, pyrogallic acid is easy to oxidize in the air, and the pyrogallic acid is combined with a polyacrylamide chain segment to generate strong viscosity after being oxidized, so that the dispersed wood chips can be tightly adhered together, the polyacrylamide with higher crosslinking degree and the sodium alginate form a double-network structure to form a polymer wood framework to improve the strength of the wood, meanwhile, the pyrogallic acid or the oxidized pyrogallic acid can generate dynamic chemical bonds with borate, the chemical bonds can be released under the condition of more water and can be reformed under the condition of less water, so that water can be added for repairing when the wood has slight cracks, so that the raw materials are hot-pressed to obtain the wood which has certain strength and can be repaired by self, and the raw materials do not contain formaldehyde.

Although the inside polyacrylamide of the wood provided by the invention is decomposed when encountering open fire, the generated gas is CO₂And NO₂The smell generated during combustion is the smell generated during combustion of wood, and the gas generated during combustion of the phenolic composite board contains a large amount of toxic gas, so that the wood provided by the invention is safe and healthy.

Drawings

FIG. 1 is a microscopic image of wood produced in example 1 of the present invention.

FIG. 2 is a graph showing the results of tensile strengths of example 1 of the present invention and comparative example 1.

FIG. 3 is a photograph of wood produced in example 1 of the present invention and comparative example 2; wherein fig. 3a is a picture of wood of comparative example 2 and fig. 3b is a picture of wood of example 1.

FIG. 4 is a photograph of the burning of wood produced in example 1 of the present invention; where figure 4a is wood before burning, figure 4b is wood in burning, and figure 4c is the moment away from the open flame; figure 4d shows the wood after burning.

FIG. 5 is a graph showing the results of comparing the strength of the wood produced in example 1 of the present invention with that of the wood after restoration; wherein, fig. 5a is a picture of the wood prepared in example 1, and fig. 5b is a picture of the repaired wood.

Detailed Description

The specific embodiment provides wood which is prepared by mixing raw materials and then carrying out hot pressing; the raw materials comprise, by mass, 70-75% of sawdust, 6-8% of sodium alginate solution, 0.8-1.5% of borate, 0.1-0.3% of pyrogallic acid, 15-20% of acrylamide, 0.1-0.3% of N, N-dimethyl bisacrylamide, 2-3% of ammonium persulfate and 100% in total; further, the mass concentration of the sodium alginate solution is 1-2%; the borate is sodium tetraborate.

The specific embodiment also provides a wood manufacturing method, which comprises the following steps:

s0, wood chips are pretreated, and the wood chips are soaked in a sodium hydroxide solution for 3-4 days; the wood chips are composed of lignin and cellulose, the cellulose is a structural substance, and partial lignin can be removed by soaking the wood chips in a sodium hydroxide solution, so that the strength is improved;

s1, adding a sodium alginate solution with the mass concentration of 1-2% into the pretreated wood chips according to the mixture ratio of the raw materials, and mixing for 15-20min to obtain a first mixed solution;

s3, adding acrylamide, N, N-dimethyl bisacrylamide and ammonium persulfate into the second mixed solution, and reacting in an ice-water bath to obtain a mixture; refrigerating the mixture at-30 ℃ to 0 ℃; the reaction in the ice-water bath is to reduce the reaction temperature, the main body of the material is realized by thermally initiating acrylamide polymerization, and the ice-water bath or cold storage is used for preventing the reaction, so that the polymerization reaction is prevented from occurring in advance, and the strength and the performance of wood formed in the subsequent hot pressing are influenced.

S4, filtering and hot-pressing the mixture to obtain wood in a hot-pressing mode of firstly pressurizing and then heating; the hot pressing conditions are as follows: the hot pressing temperature is 60-100 ℃, and the hot pressing strength is 30-50 MPa.

The reaction formula of pyrogallic acid (PG), sodium tetraborate (Borate) is as follows:

the specific embodiment also comprises a composite board which comprises the wood or the wood prepared by the manufacturing method.

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Example 1

This example presents a wood, made by mixing the raw materials, followed by hot pressing; the raw materials comprise, by mass, 70% of sawdust, 6.6% of sodium alginate solution, 0.94% of sodium tetraborate, 0.19% of pyrogallic acid, 19.63% of acrylamide, 0.19% of N, N-dimethyl bisacrylamide, 2.45% of ammonium persulfate and 100% of total; further, the mass concentration of the sodium alginate solution is 1%.

The embodiment further provides a manufacturing method of the wood, which includes the following steps:

s0, wood chips are pretreated, and the wood chips are soaked in a sodium hydroxide solution for 3 days;

s1, adding a sodium alginate solution with the mass concentration of 1% into the pretreated wood chips according to the mixture ratio of the raw materials, and mixing for 15min to obtain a first mixed solution;

s2, adding sodium tetraborate and pyrogallic acid into the first mixed solution, and continuously stirring to obtain a second mixed solution;

s3, adding acrylamide, N, N-dimethyl bisacrylamide and ammonium persulfate into the second mixed solution, and reacting in an ice-water bath to obtain a mixture; refrigerating the mixture at-18 ℃;

s4, filtering and hot-pressing the mixture to obtain wood in a mode of pressurizing and then heating; the hot pressing conditions are as follows: the hot pressing temperature is 80 ℃, and the hot pressing strength is 30 MPa. As can be seen from fig. 1, the wood chips are clearly seen to be bonded together in the wood produced in this example. It should be noted that FIG. 1 was obtained by a polarizing microscope model C40P, which is available from Ningbo Shunhu instruments Ltd.

Example 2

This example presents a wood, made by mixing the raw materials, followed by hot pressing; the raw materials comprise 73% of sawdust, 7.2% of sodium alginate solution, 1.2% of sodium tetraborate, 0.3% of pyrogallic acid, 15% of acrylamide, 0.3% of N, N-dimethyl bisacrylamide and 3% of ammonium persulfate, wherein the total amount is 100%; further, the mass concentration of the sodium alginate solution is 1.5%.

s0, wood chips are pretreated, and the wood chips are soaked in a sodium hydroxide solution for 4 days;

s1, adding a sodium alginate solution with the mass concentration of 1.5% into the pretreated wood chips according to the mixture ratio of the raw materials, and mixing for 20min to obtain a first mixed solution;

s3, adding acrylamide, N, N-dimethyl bisacrylamide and ammonium persulfate into the second mixed solution, and reacting in an ice-water bath to obtain a mixture; refrigerating the mixture at-30 ℃;

s4, filtering and hot-pressing the mixture to obtain wood in a mode of pressurizing and then heating; the hot pressing conditions are as follows: the hot pressing temperature is 60 ℃, and the hot pressing strength is 50 MPa.

Example 3

This example presents a wood, made by mixing the raw materials, followed by hot pressing; the raw materials comprise, by mass, 75% of sawdust, 6% of sodium alginate solution, 1% of sodium tetraborate, 0.2% of pyrogallic acid, 15% of acrylamide, 0.3% of N, N-dimethyl bisacrylamide, 2.5% of ammonium persulfate and 100% of total; further, the mass concentration of the sodium alginate solution is 2%.

s1, adding a sodium alginate solution with the mass concentration of 2% into the pretreated wood chips according to the mixture ratio of the raw materials, and mixing for 18min to obtain a first mixed solution;

s3, adding acrylamide, N, N-dimethyl bisacrylamide and ammonium persulfate into the second mixed solution, and reacting in an ice-water bath to obtain a mixture; refrigerating the mixture at-5 ℃;

s4, filtering and hot-pressing the mixture, and pressurizing and then heating to obtain wood; the hot pressing conditions are as follows: the hot pressing temperature is 1000 ℃, and the hot pressing strength is 40 MPa.

Example 4

This example presents a wood, made by mixing the raw materials, followed by hot pressing; the raw materials comprise, by mass, 70% of sawdust, 8% of sodium alginate solution, 1.5% of sodium tetraborate, 0.1% of pyrogallic acid, 17.1% of acrylamide, 0.3% of N, N-dimethyl bisacrylamide and 3% of ammonium persulfate, wherein the total amount is 100%; further, the mass concentration of the sodium alginate solution is 2%.

s3, adding acrylamide, N, N-dimethyl bisacrylamide and ammonium persulfate into the second mixed solution, and reacting in an ice-water bath to obtain a mixture; refrigerating the mixture at 0 ℃;

s4, filtering and hot-pressing the mixture, and pressurizing and then heating to obtain wood; the hot pressing conditions are as follows: the hot pressing temperature is 90 ℃, and the hot pressing strength is 45 MPa.

Comparative example 1

The wood produced by this comparative example differs from example 1 in that the wood chips have not been pretreated, i.e. have not been soaked in a sodium hydroxide solution.

From FIG. 2, it is possible to obtain a tensile strength of 6.14MPa for the wood without pretreatment, and a tensile strength of 11.03MPa for the wood with pretreatment.

Comparative example 2

The wood of this comparative example is different from example 1 in that after step S3, the mixture was filtered and put into a hot-pressed mold and dried in a drying oven at 80 ℃.

As can be seen from fig. 3, comparative example 2 has no rough surface of the wood obtained by hot pressing and is relatively loose; the surface of the compressed wood is smooth and compact.

Burning test

The wood prepared in example 1 is subjected to burning treatment on open fire, the wood before burning is complete and flat as can be seen from fig. 4a, the wood is extinguished after leaving a fire source as can be seen from fig. 4b to 4d, and black smoke is generated when the wood is not burned to produce open fire, which indicates that the wood is not easy to ignite.

Repair test

The method of example 1 was used to produce block wood, which was further cut into 8 pieces, after which 8 small pieces of wood were placed back into the mold again and dried in an oven with water at 80 ℃, after drying, water was added again and dried again, and the procedure was repeated five times to produce repaired wood. As can be seen from FIG. 5, the wood obtained in example 1 was compressed to a compression ratio of 0.72 at which it collapsed and had a compressive strength of 9.07MPa, while the repaired wood was compressed to a compression ratio of 0.61 at which it collapsed and had a compressive strength of 4.23 MPa. Therefore, the repaired wood also has better strength. And it can be seen from a comparison of fig. 5a and 5b that the shape of the repaired wood is substantially restored.

The above-described embodiments of the present invention should not be construed as limiting the scope of the present invention. Any other corresponding changes and modifications made according to the technical idea of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. The wood is characterized in that the wood is prepared by mixing raw materials and then hot-pressing; the raw materials comprise, by mass, 70-75% of sawdust, 6-8% of sodium alginate solution, 0.8-1.5% of borate, 0.1-0.3% of pyrogallic acid, 15-20% of acrylamide, 0.1-0.3% of N, N-dimethyl bisacrylamide, 2-3% of ammonium persulfate and 100% of total.

2. The wood as claimed in claim 1, wherein the sodium alginate solution has a mass concentration of 1-2%.

3. Wood according to claim 1, characterized in that the borate is sodium tetraborate.

4. A method of making wood according to any one of claims 1 to 3, comprising the steps of:

and S4, filtering and hot-pressing the mixture to obtain the wood.

5. The method of claim 4, further comprising pre-treating the wood chips, specifically soaking the wood chips in sodium hydroxide solution for 3-4 days, before the step S2.

6. The method of claim 4, further comprising refrigerating the mixture at-30 ℃ to 0 ℃ prior to step S4.

7. The method of claim 4, wherein said hot pressing comprises pressurizing and then heating in step S4.

8. The production method according to claim 7, wherein in step S4, the conditions of the hot pressing are: the hot pressing temperature is 60-100 ℃, and the hot pressing strength is 30-50 MPa.

9. The method of claim 4, wherein the first mixed solution is obtained by mixing for 15 to 20min in step S1.

10. A composite panel comprising wood according to any one of claims 1 to 3 or wood produced by the method of manufacture according to any one of claims 4 to 9.