CN114474263A - Preparation method of environment-friendly plywood - Google Patents
Preparation method of environment-friendly plywood Download PDFInfo
- Publication number
- CN114474263A CN114474263A CN202111571372.6A CN202111571372A CN114474263A CN 114474263 A CN114474263 A CN 114474263A CN 202111571372 A CN202111571372 A CN 202111571372A CN 114474263 A CN114474263 A CN 114474263A
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- China
- Prior art keywords
- plate blank
- plywood
- adhesive
- friendly plywood
- coating
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27D—WORKING VENEER OR PLYWOOD
- B27D1/00—Joining wood veneer with any material; Forming articles thereby; Preparatory processing of surfaces to be joined, e.g. scoring
- B27D1/04—Joining wood veneer with any material; Forming articles thereby; Preparatory processing of surfaces to be joined, e.g. scoring to produce plywood or articles made therefrom; Plywood sheets
- B27D1/08—Manufacture of shaped articles; Presses specially designed therefor
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27K—PROCESSES, APPARATUS OR SELECTION OF SUBSTANCES FOR IMPREGNATING, STAINING, DYEING, BLEACHING OF WOOD OR SIMILAR MATERIALS, OR TREATING OF WOOD OR SIMILAR MATERIALS WITH PERMEANT LIQUIDS, NOT OTHERWISE PROVIDED FOR; CHEMICAL OR PHYSICAL TREATMENT OF CORK, CANE, REED, STRAW OR SIMILAR MATERIALS
- B27K5/00—Treating of wood not provided for in groups B27K1/00, B27K3/00
- B27K5/007—Treating of wood not provided for in groups B27K1/00, B27K3/00 using pressure
- B27K5/0075—Vacuum
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27M—WORKING OF WOOD NOT PROVIDED FOR IN SUBCLASSES B27B - B27L; MANUFACTURE OF SPECIFIC WOODEN ARTICLES
- B27M1/00—Working of wood not provided for in subclasses B27B - B27L, e.g. by stretching
- B27M1/08—Working of wood not provided for in subclasses B27B - B27L, e.g. by stretching by multi-step processes
Abstract
The invention belongs to the technical field of wood processing, and particularly relates to a preparation method of an environment-friendly plywood, which comprises the following steps of (1) drying: drying the wood veneer at 60-70 ℃ until the water content is 3-8% to obtain a dry wood veneer; (2) gluing: coating an adhesive on the surface of the adjacent bonded and dried wood veneer to obtain a coated plate blank; (3) assembling: assembling the glued plate blank to obtain a blank assembling plate; (4) cold pressing: cold pressing under the pressure of 0.8-1.0 MPa; (5) hot pressing: hot pressing at 200-; (6) and (3) vacuum treatment: putting the hot-pressed plate blank into a vacuum tank, and vacuumizing to obtain a processed plate blank; (7) sealing the coating: coating paraffin on the periphery of the processed plate blank; (8) finishing, sanding and edge cutting. The plywood prepared by the method disclosed by the invention is low in formaldehyde content, strong in bonding strength and improved in environmental friendliness.
Description
Technical Field
The invention belongs to the technical field of wood processing, and particularly relates to a preparation method of an environment-friendly plywood.
Background
Plywood is a three-layer or multi-layer plate material made up by using wood segments and making them be rotary-cut into single board or sliced into thin wood and using adhesive to make them be glued together, and usually using odd number of layers of single board and making the fibre directions of adjacent layers of single board be mutually perpendicular. The plywood is one of common furniture materials, is one of three large plates of an artificial plate, and can also be used as a material for airplanes, ships, trains, automobiles, buildings, packing boxes and the like. A group of veneers are typically assembled and glued perpendicular to each other in the direction of the adjacent layers of wood grain, and the skins and inner sheets are typically symmetrically disposed on either side of the center layer or core. The glued veneer is pressed into the wood grain board blank by the criss-cross matching of the glued veneer according to the wood grain direction under the condition of heating or not heating. The number of layers is generally odd, and a few are even. The difference of physical and mechanical properties in the longitudinal and transverse directions is small. The types of plywood commonly used are plywood, plywood and the like. The plywood can improve the utilization rate of the wood and is a main way for saving the wood.
Along with the continuous improvement of the living standard of people, the requirements of people on the living environment are higher and higher, the environmental protection performance of the plywood used as a building material receives more and more attention, the formaldehyde release problem of the plywood provided by the above patents and the prior art always troubles users, and the application of the plywood in the field of building materials is limited.
The plywood on the market at present releases a large amount of free formaldehyde in the production and use processes to cause indoor air pollution, great threats are generated to the health of producers and consumers, and the plywood obtained by using the formaldehyde-free adhesive has low bonding strength. Therefore, it is necessary to develop a method for preparing environment-friendly plywood with low formaldehyde content and high bonding strength.
Disclosure of Invention
The invention aims to solve the technical problems and provides the preparation method of the environment-friendly plywood, and the plywood prepared by the method is low in formaldehyde content and high in environment friendliness.
The technical scheme of the invention is as follows:
the invention provides a preparation method of an environment-friendly plywood, which comprises the following steps:
(1) and (3) drying: drying the wood veneer at 60-70 ℃ until the water content is 3-8% to obtain a dry wood veneer;
(2) gluing: coating adhesive on the surfaces of the adjacent dry wood veneers with the adhesive coating amount of 150 plus 180g/m2Obtaining a gluing plate blank;
(3) assembling: assembling the glued plate blank to obtain a blank assembling plate;
(4) cold pressing: cold pressing under the pressure of 0.8-1.0 MPa;
(5) hot pressing: hot pressing at 200-;
(6) and (3) vacuum treatment: putting the hot-pressed plate blank into a vacuum tank, and vacuumizing to obtain a processed plate blank;
(7) sealing the coating: coating paraffin on the periphery of the processed plate blank;
(8) finishing, sanding and edge cutting.
In order to obtain plywood with low formaldehyde content and high bonding strength, in step (2) of the invention, the adhesive is preferably a mixture of melamine formaldehyde resin adhesive, isocyanate resin adhesive and dehydroacetic acid. More preferably, in step (2) of the present invention, the adhesive is a mixture of melamine formaldehyde resin adhesive, isocyanate resin adhesive and dehydroacetic acid in a weight ratio of 25-35:3-8: 0.01-0.06.
The glue amount is too large, and the cost is high; moreover, the adhesive layer is too thick, the internal stress is increased, and the adhesive is easy to penetrate; the glue amount is too small, which is not beneficial to the infiltration of glue solution, and the glue layer is not complete. In order to improve the bonding strength of the plywood, the glue coating amount is preferably 150-180g/m in the step (2) of the invention2。
In order to improve the uniformity of the inner glue layer during gluing, in step (4), the cold pressing time is preferably 5-8 min.
In order to improve the strength of the plywood, in the step (5) of the invention, the hot-pressed board blank is dried at 60-70 ℃ until the water content is 3-5% before being placed in a vacuum tank.
In order to prevent the bubbling phenomenon at the glued part of the plywood and reduce the gluing strength of the plywood, the pressure cannot be released immediately after the pressure is applied, and the pressure is required to be slowly released, and preferably, the pressure is released to the normal pressure within 2-3min in the step (5) of the invention.
In order to reduce the free formaldehyde content of the plywood, vacuum treatment is carried out after hot pressing, and preferably, in the step (6) of the invention, vacuum is carried out until the vacuum degree is (-0.10) - (-0.02) MPa.
In order to further reduce the content of free formaldehyde in the plywood, the periphery of the plywood subjected to vacuum treatment is subjected to sealing treatment, and preferably, in the step (7) of the invention, the paraffin is added in an amount of 0.15-0.35% of the weight of the treated slab. The plywood treated by the paraffin can reduce the free formaldehyde emission speed, reduce the emission amount of formaldehyde in unit time and improve the environmental protection performance of the plywood.
In order to obtain plywood with better performance, it is necessary to select high-quality wood veneers, and preferably, in the step (1) of the invention, the wood veneers are derived from one of Yunnan pine, rubber trees and sweetgum trees.
Due to the adoption of the technical scheme, the invention has the beneficial effects that:
1. according to the method, the raw material proportion of the adhesive is adopted, so that the bonding strength of the plywood can be improved, the plywood with ultralow formaldehyde release amount can be obtained, and the obtained plywood reaches E0And (4) grading environmental protection grade.
2. In the method, the formaldehyde release amount is reduced and the environmental protection performance of the plywood is improved by matching with vacuumization and paraffin addition under the condition of improving the formula of the adhesive.
Detailed Description
The technical solutions in the embodiments of the present invention are clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
The preparation method of the environment-friendly plywood comprises the following steps:
(1) and (3) drying: taking a rubber tree log, cutting, rotary cutting, cutting into a wood veneer, and drying the wood veneer at 60 ℃ until the water content is 3% to obtain a dry wood veneer;
(2) gluing: coating adhesive on the surfaces of the adjacent dry wood veneers with the adhesive amount of 150g/m2Obtaining a gluing plate blank;
(3) assembling: assembling the glued plate blank to obtain a blank assembling plate;
(4) cold pressing: cold pressing for 8min under the pressure of 0.8 MPa;
(5) hot pressing: hot pressing at 200 deg.C under 4MPa for 8min, and relieving pressure to normal pressure within 3min to obtain hot pressing plate blank;
(6) and (3) vacuum treatment: before the hot-pressed plate blank is placed into a vacuum tank, drying the hot-pressed plate blank at 60 ℃ until the water content is 3%, placing the hot-pressed plate blank into the vacuum tank, and vacuumizing until the vacuum degree is-0.02 MPa to obtain a treated plate blank;
(7) sealing the coating: coating paraffin accounting for 0.15 percent of the weight of the processed plate blank on the periphery of the processed plate blank;
(8) finishing, sanding and edge cutting.
In the step (2), the adhesive is a mixture of melamine formaldehyde resin adhesive, isocyanate resin adhesive and dehydroacetic acid with a weight ratio of 25:8: 0.01.
Example 2
The preparation method of the environment-friendly plywood comprises the following steps:
(1) and (3) drying: taking a maple log, cutting, rotary cutting, cutting into a wood veneer, and drying the wood veneer at 70 ℃ until the water content is 8% to obtain a dry wood veneer;
(2) gluing: coating adhesive on the surface of the adjacent adhered and dried wood veneer, wherein the adhesive coating amount is 180g/m2Obtaining a gluing plate blank;
(3) assembling: assembling the glued plate blank to obtain an assembled blank plate;
(4) cold pressing: cold pressing at 1.0MPa for 5 min;
(5) hot pressing: hot pressing at 210 deg.C under 2MPa for 5min, and relieving pressure to normal pressure within 2min to obtain hot pressing plate blank;
(6) and (3) vacuum treatment: before the hot-pressed plate blank is placed into a vacuum tank, drying the hot-pressed plate blank at 70 ℃ until the water content is 5%, placing the hot-pressed plate blank into the vacuum tank, and vacuumizing until the vacuum degree is-0.10 MPa to obtain a treated plate blank;
(7) sealing the coating: coating paraffin accounting for 0.35 percent of the weight of the processed plate blank on the periphery of the processed plate blank;
(8) finishing, sanding and edge cutting.
In the step (2), the adhesive is a mixture of melamine formaldehyde resin adhesive, isocyanate resin adhesive and dehydroacetic acid, wherein the weight ratio of the melamine formaldehyde resin adhesive to the isocyanate resin adhesive to the dehydroacetic acid is 35:3: 0.06.
Example 3
The preparation method of the environment-friendly plywood comprises the following steps:
(1) and (3) drying: cutting Yunnan pine log, rotary cutting, cutting into wood veneer, and drying the wood veneer at 65 deg.C until the water content is 6% to obtain dried wood veneer;
(2) gluing: coating adhesive on the surface of the adjacent adhered and dried wood veneer, wherein the adhesive coating amount is 160g/m2Obtaining a gluing plate blank;
(3) assembling: assembling the glued plate blank to obtain a blank assembling plate;
(4) cold pressing: cold pressing for 7min under the pressure of 0.9 MPa;
(5) hot pressing: hot pressing at 205 deg.C under 3MPa for 7min, and releasing pressure to normal pressure within 3min to obtain hot pressing plate blank;
(6) and (3) vacuum treatment: before the hot-pressed plate blank is placed into a vacuum tank, drying the hot-pressed plate blank at 65 ℃ until the water content is 4%, placing the hot-pressed plate blank into the vacuum tank, and vacuumizing until the vacuum degree is-0.06 MPa to obtain a treated plate blank;
(7) sealing the coating: coating paraffin accounting for 0.25 percent of the weight of the processing slab on the periphery of the processing slab;
(8) finishing, sanding and edge cutting.
In the step (2), the adhesive is a mixture of melamine formaldehyde resin adhesive, isocyanate resin adhesive and dehydroacetic acid, wherein the weight ratio of the melamine formaldehyde resin adhesive to the isocyanate resin adhesive to the dehydroacetic acid is 20:5: 0.03.
Comparative example 1
The difference from example 3 is: in the step (2), the adhesive is a mixture of melamine formaldehyde resin adhesive and dehydroacetic acid with a weight ratio of 25: 0.03. The rest is the same as example 3.
Comparative example 2
The difference from example 3 is: step (6) is omitted. The rest is the same as example 3.
Comparative example 3
The difference from example 3 is: step (7) is omitted. The rest is the same as example 3.
Comparative example 4
The difference from example 3 is: in the step (7), sealing the coating: the treated mat was coated with paraffin at 1% of the weight of the treated mat. The rest is the same as example 3.
Comparative example 5 differs from example 3 in that: in the step (7), sealing the coating: the treated mat was coated with paraffin at 0.1% of the weight of the treated mat. The rest is the same as example 3.
The formaldehyde emission and the bond strength (class II) of the plywood prepared in examples and comparative examples were measured according to GB/T9846-2004 national plywood standard, and the results are shown in tables 1 and 2.
TABLE 1 Formaldehyde emission for the different treated veneers
As can be seen from Table 1, the method of the present invention can improve the bonding strength of plywood, especially plywood reaching E, while reducing the formaldehyde content0Meanwhile, as can be seen from comparative examples 1 and 2, the bonding strength and formaldehyde emission of the plywood cannot reach E by changing the raw material type of the adhesive or not performing vacuum-pumping treatment0The grade of environmental protection is graded, and in addition, as can be seen from the data of comparative examples 3 to 7, the plywood obtained by changing the addition amount of the paraffin or not adding the paraffin can not reach E0And (5) grading ring environmental protection grade.
The above description is intended to describe in detail the preferred embodiments of the present invention, but the embodiments are not intended to limit the scope of the claims of the present invention, and all equivalent changes and modifications made within the technical spirit of the present invention should fall within the scope of the claims of the present invention.
Claims (10)
1. The preparation method of the environment-friendly plywood is characterized by comprising the following steps:
(1) and (3) drying: drying the wood veneer at 60-70 ℃ until the water content is 3-8% to obtain a dry wood veneer;
(2) gluing: coating an adhesive on the surface of the adjacent bonded and dried wood veneer to obtain a coated plate blank;
(3) assembling: assembling the glued plate blank to obtain a blank assembling plate;
(4) cold pressing: cold pressing under the pressure of 0.8-1.0 MPa;
(5) hot pressing: hot pressing at 200-;
(6) and (3) vacuum treatment: putting the hot-pressed plate blank into a vacuum tank, and vacuumizing to obtain a processed plate blank;
(7) sealing the coating: coating paraffin on the periphery of the processed plate blank;
(8) finishing, sanding and edge cutting.
2. The method for preparing environment-friendly plywood as claimed in claim 1, wherein: in the step (2), the adhesive is a mixture of melamine formaldehyde resin adhesive, isocyanate resin adhesive and dehydroacetic acid.
3. The method for preparing environment-friendly plywood as claimed in claim 2, wherein: in the step (2), the adhesive is a mixture of melamine formaldehyde resin adhesive, isocyanate resin adhesive and dehydroacetic acid, wherein the weight ratio of the melamine formaldehyde resin adhesive to the isocyanate resin adhesive to the dehydroacetic acid is 25-35:3-8: 0.01-0.06.
4. The method for preparing environment-friendly plywood as claimed in claim 1, wherein: in the step (2), the glue coating amount is 150-2。
5. The method for preparing environment-friendly plywood as claimed in claim 1, wherein: in the step (4), the cold pressing time is 5-8 min.
6. The method for preparing environment-friendly plywood as claimed in claim 1, wherein: in the step (5), before the hot-pressed plate blank is placed into a vacuum tank, the hot-pressed plate blank is dried at the temperature of 60-70 ℃ until the water content is 3-5%.
7. The method for preparing environment-friendly plywood as claimed in claim 1, wherein: in the step (5), the pressure is relieved to the normal pressure within 2-3 min.
8. The method for preparing environment-friendly plywood as claimed in claim 1, wherein: in the step (6), vacuum pumping is carried out until the vacuum degree is (-0.10) - (-0.02) MPa.
9. The method for preparing environment-friendly plywood as claimed in claim 1, wherein: in the step (7), the addition amount of the paraffin is 0.15-0.35% of the weight of the processed slab.
10. The method for preparing environment-friendly plywood as claimed in claim 1, wherein: in the step (1), the wood veneer is derived from one of Yunnan pine, rubber tree and sweetgum tree.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111571372.6A CN114474263A (en) | 2021-12-21 | 2021-12-21 | Preparation method of environment-friendly plywood |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111571372.6A CN114474263A (en) | 2021-12-21 | 2021-12-21 | Preparation method of environment-friendly plywood |
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| CN114474263A true CN114474263A (en) | 2022-05-13 |
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| CN202111571372.6A Pending CN114474263A (en) | 2021-12-21 | 2021-12-21 | Preparation method of environment-friendly plywood |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115674371A (en) * | 2022-09-20 | 2023-02-03 | 贺州市恒轩木业有限公司 | Preparation method of low-formaldehyde environment-friendly plywood and low-formaldehyde environment-friendly plywood |
-
2021
- 2021-12-21 CN CN202111571372.6A patent/CN114474263A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115674371A (en) * | 2022-09-20 | 2023-02-03 | 贺州市恒轩木业有限公司 | Preparation method of low-formaldehyde environment-friendly plywood and low-formaldehyde environment-friendly plywood |
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