CN109591122B - Method for vacuum compression and densification of wood material - Google Patents
Method for vacuum compression and densification of wood material Download PDFInfo
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- CN109591122B CN109591122B CN201910107522.4A CN201910107522A CN109591122B CN 109591122 B CN109591122 B CN 109591122B CN 201910107522 A CN201910107522 A CN 201910107522A CN 109591122 B CN109591122 B CN 109591122B
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- 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
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Abstract
本发明公开了一种木质材料真空压缩密实化的方法，属于木质材料生产制备领域。本发明通过在真空条件下对木材进行热压定形处理，处理后的木材比模量大，解决了现有木材压缩密实技术的热压定形时间长，制造效率低、变色和尺寸不稳定性等技术问题；在真空条件下进行木质材料的压缩密实化制造，也提高了木质胶合材料的胶合强度。The invention discloses a method for vacuum compression and compaction of wood materials, which belongs to the field of wood material production and preparation. In the present invention, the wood is subjected to hot-pressing and setting treatment under vacuum conditions, and the treated wood has a larger specific modulus, thereby solving the problems of long hot-pressing setting time, low manufacturing efficiency, discoloration and dimensional instability of the existing wood compression and compaction technology. Technical problem; compressing and densifying wood materials under vacuum conditions also improves the bonding strength of wood glued materials.
Description
The invention is a divisional application, a parent application number: 201711474145.5, original case name: a method for compressing and densifying a wood material, which is disclosed by the application date of the mother application: 12 and 29 months in 2017.
Technical Field
The invention belongs to the field of production and preparation of wood materials, and particularly relates to a method for compressing and compacting wood and improving the bonding strength of a wood composite material.
Background
China, the artificial forest reaches 5325 million hectares, which is the first place in the world. Compared with natural forest, the artificial forest has the characteristics of fast growth, high growth quantity, convenient development, early benefit acquisition, stable wood specification and quality, convenient processing and utilization and the like. However, the artificial forest has some material defects, such as poor quality, loose structure, low strength and hardness, no wear resistance and easy moisture absorption, so that the industrial application of the artificial forest is greatly limited. Therefore, improving and enhancing the relative performance of fast growing wood is one of the main methods for expanding the utilization range of the fast growing wood.
Commonly used wood strengthening treatment methods include resin infusion and compression densification. The most widespread method for impregnating wood is vacuum impregnation, i.e. the wood is first vacuumized under a certain negative pressure, then the impregnating resin is injected into the wood in a tank by the pressure difference between the inside and the outside of the treatment tank, and the impregnation is maintained for a corresponding time. However, wood is a porous and heterogeneous natural material and has large anisotropy, so that after wood is impregnated with various low molecular weight resins, the distribution of the resins in the wood is often uneven, and the added chemical reagents have certain influence on human health and the global environment. However, in the prior art, wood is impregnated in a vacuum state and pressurized (hot pressed), no relevant literature is provided, and if the wood is simply impregnated in the vacuum state and hot pressed, the impregnation and hot pressing effects are not achieved, and the problems of pollution of chemical reagents to human health and global environment and the like cannot be solved.
Compression and densification are a technology for high-quality utilization of inferior materials. The compression and densification of the fast growing wood is an important direction for modifying the fast growing wood, and aims to improve the relevant physical and mechanical properties of the fast growing wood. After the fast growing wood is subjected to compression and densification treatment, the hardness, the wear resistance and the dimensional stability of the fast growing wood can be improved, so that the fast growing wood can partially replace broad-leaved wood for use.
The conventional wood compression and densification technology mainly comprises three steps of softening treatment before compression, transverse compression and deformation fixation after compression, and the technology has long production time and low efficiency. Although the density of the wood treated by the technology is increased, the specific modulus is not improved, even the specific modulus of the wood is reduced, so that the performance of the wood is not improved well. In addition, in the process of compressing and compacting the wood, polysaccharide, hemicellulose and extract in the chemical components of the wood are subjected to a series of chemical changes such as degradation, oxidation, polycondensation and the like, and the content of colored substances is increased, so that the surface color of the wood is deepened, and the attractiveness and the quality of a product are influenced.
Chinese patent, publication number: CN102198679B, published: 26/3/2014, a method for enhancing the fast-growing flooring is disclosed. The method comprises the following steps: a. densifying the fast-growing floor base material by adopting a hot press; b. the densified fast-growing plate is subjected to surface carbonization on a hot pressing plate; c. and (3) carrying out gas-solid two-phase chemical lamination on the nitrogen plasma and the carbon element by adopting a radio frequency plasma modification method to carry out nitridation. The fast-growing floor material treated by the method has the advantages of high surface hardness and wear resistance, and has the following defects: the method has the advantages that the process is complex from densification to carbonization to nitridation, the processing period is long, the hot pressing densification is carried out under the conditions that the hot pressing temperature is 80-120 ℃, the hot pressing pressure is 0.8-2.0 MPa, and the time is 5-15 min, so that the plate can rebound and has poor dimensional stability; in addition, after the base material is subjected to densification treatment, the base material is subjected to carbonization treatment in a high-temperature environment of more than 200 ℃, so that the surface of the wood is easy to discolor, and the texture and color of the fir are damaged.
Chinese patent, publication number: CN 101875207 a, published: 11/3/2010, discloses a processing method for in-situ densification and antibacterial and degerming functions of low-quality fast-growing logs, which comprises the following steps: the filling agent is used for carrying out in-situ compaction and antibacterial treatment on the low-quality fast growing wood in a vacuum pressurizing tank through pressurizing and vacuumizing processes. The invention has low operation temperature, no compression to wood and in-situ compaction. However, it has disadvantages in that: (1) the invention needs to add extra filler, thus adding extra cost and having higher cost; (2) the time for the filler to permeate into the wood is longer, so that the whole processing period of the board is longer; (3) the density of the wood is greatly increased after the wood is soaked, although the bending elastic modulus is improved by 36.2%, the specific modulus of the material is greatly reduced, and the performance of the material is influenced.
Chinese patent, publication number: CN103433982B, published: in 2015, 8, 5 days, a staggered laminated plate processing method is disclosed, which specifically comprises preparation of a laminate, preparation of a composite modifier, modification and reinforcement of a surface layer plate, finger joint of the laminate, gluing of the laminate, assembly, pressing and later-stage processing. The surface layer plate modifying and reinforcing process includes setting the surface layer plate inside sealed pressure tank, vacuumizing and pressurizing the pressure tank repeatedly, soaking the composite modifier into the surface layer plate under the action of pressure to eliminate excessive composite modifier from the surface layer of the plate, and vacuumizing the pressure tank. In the assembly and pressing process, the modified reinforced laminate is arranged on the surface layer to be assembled in a mode that the grain directions of the adjacent laminates are mutually vertical, and the assembled laminate is placed into a press to be cold-pressed and molded, and meanwhile, lateral pressure is applied. The disadvantages are as follows: (1) the time for the composite modifier to permeate into the wood is longer, so that the whole processing period of the board is longer; (2) the invention puts the board in the pressure tank and vacuumizes to carry out the dipping treatment and modification, and then carries out the press compression and reinforcement treatment on the board after the pressure dipping treatment under the conventional state, the modifier is difficult to permeate into the wood with dense grains and holes such as fast-growing fir, and the surface performance of the material after the dipping treatment is also changed. Various drawbacks of conventional impregnation treatments still exist.
In addition, the formation of the bonding strength during wood bonding is a complex process, which is mainly divided into the following 5 steps: flow, transfer, penetrate, wet, and cure. The urea-formaldehyde resin adhesive is often adopted in the production of plywood at present, and in plywood or other wooden combined material manufacturing process, because timber is porous material, can aggravate the gluing agent and permeate veneer department when the hot pressing, the gluing agent content of cementing layer department reduces, seriously influences the veneer effect, and then has reduced the final bonding strength of plywood. This is also a technical problem to be solved by the prior art or the industry.
Disclosure of Invention
1. Problems to be solved
Aiming at the defects in the existing impregnation treatment, and the problems of long production period, high production cost, low utilization efficiency of production equipment, poor mechanical property of products and the like in the wood compression and densification technology and the conventional wood composite material manufacturing and processing, the invention discloses a method for compressing and densifying a wood material, which can simultaneously achieve the purposes of compression, color fixation and shaping on the wood material, and the mechanical strength of the processed wood material completely meets the requirements.
2. Technical scheme
In order to solve the problems, the invention adopts the following technical scheme:
a method for compressing and densifying a wood material comprises the following steps:
pressurizing the wooden material in a vacuum state; the pressurizing pressure is 1-4 MPa; and after the pressurization time is reached, removing the vacuum, and carrying out pressure relief and cooling.
Preferably, the wooden material is hot-pressed in a vacuum state; the hot pressing temperature is 100-220 ℃, and the hot pressing pressure is 1-4 MPa; and after the hot pressing time is reached, removing vacuum, and carrying out pressure relief and cooling.
The hot pressing is carried out in a vacuum state, and the vacuum degree is-0.1 MPa to-0.09 MPa.
The method for compressing and densifying the wood material further comprises the steps of drying and sanding the surface of the wood material; and cutting the wooden material after the drying and surface sanding treatment.
The wood material is wood or a wood composite material, and the wood composite material is plywood, structural laminated wood, a shaving board or structural laminated veneer lumber.
The thickness of the wood after the drying and surface sanding treatment is 18-22 mm; the final water content is 10 +/-2%.
The wood material is obtained by vacuumizing wood before compression, the vacuum degree is-0.1 MPa to-0.09 MPa, the hot pressing temperature is 160 ℃ to 220 ℃, the hot pressing time is 15min to 45min, and the hot pressing pressure is 2MPa to 4 MPa; namely, the whole wood compression and densification process is always in a vacuum state.
The manufacturing method for improving the bonding strength of the wood material by compressing and densifying the wood material comprises the following steps:
(1) rotary cutting or slicing the wood into wood veneers;
(2) drying the wood veneer processed in the step (1);
(3) coating adhesive on the wood veneer processed in the step (2);
(4) assembling the wood veneers treated in the step (3);
(5) carrying out vacuum hot pressing on the plate blank treated in the step (4), wherein the vacuum degree is-0.1 MPa to-0.09 MPa, the hot pressing temperature is 100-120 ℃, the hot pressing time is 50-90s/mm, and the hot pressing pressure is 1-2 MPa;
(6) and (5) after the plate blank processed in the step (5) is subjected to hot pressing time, removing vacuum, relieving pressure, cooling, edge cutting and sanding, and finally obtaining the plywood with high bonding strength.
And (3) drying the wood veneer in the step (2) to obtain the final water content of 8 +/-3%.
The adhesive in the step (3) is urea-formaldehyde resin adhesive, and the double-side adhesive applying amount is 200-2And (5) the plate blank in the step (4) is assembled in a longitudinal-transverse-longitudinal three-layer or odd-number layer mode.
3. Advantageous effects
Compared with the prior art, the invention has the beneficial effects that:
(1) the method for compressing and densifying the wood material increases the surface layer density of the material through compression, improves the mechanical strength and improves the stability of the material. The vacuumizing treatment enables the whole hot pressing process to be carried out under the anaerobic condition, the degradation of the material content is reduced, the color of the wood is guaranteed not to be changed obviously, the migration of water inside the wood is accelerated, the hydrogen bond recombination of molecules among the chemical components of the wood is caused along with the loss of water molecules, certain chemical groups are changed to form a crosslinking effect, and under the action of external force, the directionality among the microfibrils is improved, the crystallinity is improved, and the compression effect is improved. The wood is softened and partially degraded by lignin and hemicellulose under the high temperature condition, microfibril is easy to move, molecular parts forming the matrix substance are partially cut off, internal stress is quickly relaxed, and when the temperature is reduced, the matrix substance returns to a glass state from a viscous state, so that the elastic deformation of the microfibril is inhibited, and the compression deformation is fixed. Therefore, the invention simultaneously realizes the functions of hot pressing, color fixing and shaping, and solves the problems that wood is easy to discolor and has poor stability under the common hot pressing;
(2) secondly, the method for compressing and densifying the wood material has the advantages that the boiling point of liquid under the vacuum condition is low, the number of molecules in unit volume is greatly reduced, the collision probability of evaporated molecules is reduced, and the evaporated molecules are not easy to return. When the high-temperature hot-pressing treatment is carried out on the wood under the vacuum condition, the pressure of the vacuum environment is lower, the moisture in the wood is easy to evaporate out under the action of differential pressure, and the densification of the wood is promoted under the combination of strict pressure and temperature;
(3) compared with the prior art, the wood material densification method provided by the invention does not need any additive to carry out impregnation treatment and the like on the wood, so that the whole processing and treating process is green and environment-friendly, the prepared wood material does not contain harmful substances, the wood densification time is very short, and the production efficiency is favorably improved;
(4) according to the method for densifying the wood material, after the wood material is subjected to vacuum hot pressing treatment, hemicellulose in the solid wood board is degraded, the mass loss rate is increased, the internal porosity is reduced, the mass of wood cell wall substances contained in a unit volume is increased, the wood density is increased, the effective action area for bearing external force is enlarged, the bending-resistant elastic modulus of the material is greatly improved after the material is quickly subjected to hot pressing in a short time and under the hot pressing condition, the increase degree of the elastic modulus is greater than the increase degree of the density, and the specific modulus of the material is greatly increased;
(5) the method for densifying the wood material provided by the invention can improve the bonding strength of the wood material, and the vacuum hot pressing technology is utilized to carry out vacuum pumping treatment before hot pressing, so that the boiling point of the substance is reduced, the moisture in the wood can be vaporized at a lower temperature, the evaporation speed of the moisture on the surface of the wood is accelerated, the outward migration speed of the moisture in the wood is accelerated, the glue layer is easier to cure, the bonding strength of the wood material is improved, and the bonding time is shortened.
(6) According to the method for improving the bonding strength of the wood material, provided by the invention, the material is bonded under an anaerobic condition by using a vacuum hot pressing technology, so that the degradation degree of the content of the wood is reduced, and the color of the wood is not changed; various solid substances can adsorb some gas on the surface in an atmospheric pressure environment, and when the wood composite material is in vacuum, the adsorbed gas can be released into the environment due to the reduction of the molecular density of the gas, and the formaldehyde release amount of the wood composite material can be reduced by utilizing the vacuum technology; meanwhile, the adhesive is prevented from generating unfavorable chemical reaction at high temperature, and the gluing quality is further ensured.
Detailed Description
The invention is further described with reference to specific examples.
Example 1
The specific test steps of the experiment are as follows:
1) drying and sanding the fir board: sanding the fir wood plate with the thickness of 23-24mm to 22mm, and drying to obtain the water content of 10%.
2) Cutting the dried and surface sanded fir board: a jig saw was used to prepare a specimen of 200mm by 100mm by 20mm (axial by chordwise by radial) fir wood. And (3) accurately measuring the mass, width, thickness, length and other dimensions of the test piece (marking the position when the thickness is measured), accurately measuring the thickness to 0.02mm, recording the data of the test piece and numbering the test piece.
3) And (3) compressing the numbered test piece by using a hot press under the conditions of vacuum and normal pressure respectively (vertical wood chord direction compression): the pressure of the high-temperature hot compression treatment is 2MPa, the compression rate is 30 percent, the hot pressing time is 30min, and the hot pressing temperature is 180 ℃, 200 ℃ and 220 ℃. And after the hot pressing time is reached, removing vacuum, removing pressure, and cooling to obtain the final compressed wood. Wherein, when the vacuum hot pressing is removed, the vacuum valve is closed, the vacuum cover is opened, and then the pressure is released.
4) The thickness (measured at the mark) and weight of the test piece after the compression treatment were measured and recorded.
5) The color difference between the compressed test piece and the untreated test piece was measured and calculated using the CIE (1976) La b color system recommended by the International Commission on illumination.
6) And (4) detecting the bending elastic modulus of the compressed test piece by using a universal mechanical testing machine.
The bending modulus test data (GB/T1936.2-2009) of the wood material obtained by the procedure of example 1 are shown in Table 1.
TABLE 1 measurement data of flexural modulus of elasticity of material
TABLE 2 test piece color difference value detection data
TABLE 3 specific modulus data for vacuum hot-pressed test pieces
The implementation result shows that the bending elasticity modulus and the specific modulus of the material can be effectively improved by compressing the wood in a vacuum state, and the color difference of the surface of the material is small compared with the traditional compressed material.
Example 2
The procedure for carrying out this test was the same as in example 1, except that,
1) sawing: sanding the fir wood plate with the thickness of 21-23mm to 20mm, wherein the water content is 10%.
2) Vacuum hot pressing: the hot pressing pressure is 2MPa, the compression ratio is 30 percent, the hot pressing time is 15min, and the hot pressing temperature is 180 ℃, 200 ℃ and 220 ℃.
4) And (5) releasing the pressure.
The woody material detection data obtained by the procedure of example 2 is as follows.
TABLE 4 Experimental survey data
The vacuum compression time in example 2 was shortened by 15min as compared with example 1, and the strength improvement rate of the compressed wood was lower and the color difference value was smaller, that is, the surface color was less likely to change, as compared with example 1.
Example 3
The procedure is as in example 2 except that sanding is carried out to 18mm, the water content is 12%, the compression ratio during vacuum hot pressing is 20%, and the compression time is 30 min.
The measurement data of the woody material obtained by the procedure of example 3 are shown in Table 5:
TABLE 5 Experimental survey data
Example 4
The procedure is as in example 2 except that the vacuum compression ratio is 10% in the vacuum hot compaction, the compression time is 30min, and the hot pressing temperature is 200 ℃. The resulting compressed wood is tested according to relevant regulations and standards. The results show that the flexural modulus and the specific modulus of the test piece after the vacuum compression treatment are respectively improved by 42.77 percent and 20.91 percent compared with the material, and the color difference value is 5.92 percent.
Example 5
The procedure is as in example 2 except that the test pieces are dried before compression treatment to control the water content to 8% and the hot pressing temperature to 180 ℃, and the obtained compressed wood is tested according to relevant regulations and standards. The bending elastic modulus and the specific modulus of the test piece after vacuum hot pressing treatment are respectively improved by 33.36 percent and 10.26 percent compared with the material, and the color difference value is 6.11 percent.
Example 6
The procedure is the same as example 2 except that the test pieces are dried before compression treatment to control the water content to be 10%, the hot pressing temperature is 160 ℃, and the compressed wood obtained after the compression time is 45min is detected according to relevant regulations and standards. The bending elastic modulus and the specific modulus of the test piece after vacuum hot pressing treatment are respectively improved by 20.64 percent and 7.55 percent compared with the material, and the color difference value is 5.78 percent.
Example 7
The procedure is the same as example 2 except that the test pieces are dried before compression treatment to control the water content to 10%, and the compressed wood obtained after the compression time of 45min is subjected to pressurization to detect according to relevant regulations and standards. The bending elastic modulus and the specific modulus of the test piece after vacuum hot pressing treatment are respectively improved compared with those of the material.
Example 8
A method for compressing and densifying a wood material comprises the following steps:
1) slicing and drying: slicing the sliced Chinese fir veneer (without crack degree) with a thickness of 1.6-1.8mm, drying in a drying oven at 50 deg.C for 12 hr to obtain final water content of 8%.
2) Gluing: coating adhesive on the dried wood veneer, wherein the amount of the double-sided adhesive is 300g/m2。
3) Assembling: and preparing a slab of the three-layer plywood according to a longitudinal-transverse-longitudinal three-layer assembly mode of the plywood.
4) Vacuum hot pressing: and (3) putting the plate blank into a press, closing a vacuum cover, vacuumizing, wherein the hot pressing temperature is 110 ℃, the plate blank pressure is 1.0MPa, and the hot pressing time is 60 s/mm.
5) Pressure relief: and (4) after the hot pressing time is reached, removing vacuum, finishing the hot pressing, releasing pressure, taking out the plate blank, cooling, cutting edges and sanding to obtain the plywood.
Plywood test data (GB/T17657-2013) of the wood material obtained according to the procedure of example 1 are shown in Table 6:
table 6 bonding strength test data of plywood made of wood material
The implementation result shows that the hot pressing is carried out in a vacuum state, so that the bonding strength of the plywood can be obviously improved. The vacuum hot pressing treatment is utilized, so that the bonding strength of the wood material is obviously improved.
Example 9
The procedure is the same as example 6, except that the moisture content of the veneer is controlled to be 11% after drying, and the double-side glue application amount is 280g/m during gluing2The vacuum hot pressing temperature is 120 ℃, the plate blank pressure is 1.5MPa, the vacuum hot pressing time is 50s/mm, the obtained plywood is detected according to relevant regulations and standards, the bonding strength reaches 1.956MPa, and compared with the China fir plywood under normal pressure, the bonding strength is improved by 42.13 percent.
Example 10
The steps are the same as those of the embodiment6, the difference lies in that the moisture content of the single board is controlled to be 5% after drying, and the double-side glue applying amount is 250g/m during gluing2The vacuum hot pressing temperature is 100 ℃, the vacuum hot pressing time is 90s/mm, the bonding strength of the obtained plywood reaches 2.115MPa through detection, and the bonding strength is improved by 24.6 percent compared with the China fir plywood under normal pressure.
Example 11
The procedure is as in example 6, except that the thickness of the cedar veneer is 2mm, the moisture content is controlled to be 9% by drying, and the amount of double-sided glue application is 240g/m during gluing2The vacuum hot pressing temperature is 90 ℃, the vacuum hot pressing time is 60s/mm, the bonding strength of the obtained plywood reaches 1.879MPa through detection, and the bonding strength is improved by 37.36 percent compared with the China fir plywood under normal pressure.
Example 12
A method for compressing and densifying a wood material comprises the following steps:
1) slicing and drying: the sliced poplar veneer (without crack degree) with the thickness of 1.6-1.8mm is dried in a drying box at the temperature of 50 ℃ for 12h, and the final water content is 10%.
2) Gluing: coating the dried wood veneer with an adhesive, wherein the adhesive is phenolic resin, the solid content is 65%, and the double-sided adhesive applying amount is 300g/m2。
3) Assembling: and preparing the laminated veneer lumber with the 15-layer structure according to the assembly mode of the laminated veneer lumber.
4) Vacuum hot pressing: and (3) putting the plate blank into a press, closing a vacuum cover, vacuumizing, wherein the hot pressing temperature is 145 ℃, the plate blank pressure is 1.0MPa, and the hot pressing time is 60 s/mm.
5) Pressure relief: and (3) after the hot pressing time is reached, removing vacuum, finishing the hot pressing, releasing pressure, taking out the plate blank, cooling, cutting edges and sanding to obtain the structural laminated veneer lumber.
The structural laminated veneer lumber detection data (GB/T20241-2006) obtained according to the procedure of example 12 is shown in table 7:
table 7 bonding strength test data of veneer layer laminates
Example 13:
the manufacturing method for improving the bonding strength of the glued wood of the wood material comprises the following steps:
1) preparing materials: the sawn camphor pine sawn timber (the width is 140mm, the thickness is 10mm) has the water content of 12 percent.
2) Gluing: coating adhesive for dried pinus sylvestris, wherein the adhesive is resorcinol-phenol-formaldehyde copolymer resin, the solid content is 50%, and the double-side adhesive applying amount is 260g/m2。
3) Assembling: preparing the three-layer structure laminated wood according to the assembly mode of the laminated wood.
4) Vacuum hot pressing: and (3) putting the plate blank into a press, closing a vacuum cover, vacuumizing, wherein the hot pressing temperature is 145 ℃, the unit pressure of the plate blank is 1.0MPa, and the hot pressing time is 60 s/mm.
5) Pressure relief: and (4) after the hot pressing time is reached, removing vacuum, finishing the hot pressing, releasing pressure, taking out the plate blank, cooling, cutting edges and sanding to obtain the structural laminated wood.
The laminated wood obtained according to the procedure of example 13 is detected according to the national standard GB/T26899-2011, and the average bond line shear strength (6.74MPa) of the laminated wood produced by vacuum hot pressing meets the standard requirement (6.0MPa), and is higher than the bond line strength of the laminated wood produced under normal pressure.
Example 14
The wood composite material is a shaving board, the preparation steps are the same as the preparation method of the conventional shaving board, the adhesive is phenolic resin adhesive, and the difference lies in vacuum hot pressing: and (3) putting the plate blank into a press, closing a vacuum cover, vacuumizing, wherein the hot pressing temperature is 145 ℃, the unit pressure of the plate blank is 1.0MPa, and the hot pressing time is 60 s/mm. The particle board obtained according to the procedure of example 14 was tested, and the average bond line shear strength of the particle board produced by vacuum hot pressing was in accordance with the standard requirements and higher than the bond strength of the particle board produced at atmospheric pressure.
Claims (8)
1. A method for compressing and densifying a wood material in vacuum is characterized by comprising the following steps:
before compression, vacuumizing is carried out, namely, the whole compression and densification process is carried out under a vacuum state, the vacuum degree is-0.1 MPa to-0.09 MPa, the hot pressing time is 15min to 45min, the hot pressing pressure is 2MPa to 4MPa, the hot pressing temperature is 100 ℃ to 220 ℃, and after the hot pressing time is reached, vacuumizing, pressure relief and cooling are carried out.
2. The method for vacuum compression densification of wood-based material according to claim 1, further comprising a pre-treatment step of: firstly, drying and sanding a wood material, wherein the wood material is wood, and the moisture content is controlled to be 10 +/-2% by drying; then cutting the wood material after drying and surface sanding treatment;
and post-treatment, wherein the compression treatment is vertical wood chordwise compression, the hot pressing temperature is 160-220 ℃, and after the hot pressing time is reached, the vacuum is removed, and pressure relief and cooling are carried out to obtain the compressed wood.
3. The method for vacuum compression densification of wood-based material according to claim 2, wherein the thickness of the wood after drying and surface sanding is 18-22 mm.
4. The method for vacuum compression densification of wood-based material according to claim 1, wherein the pretreatment step comprises the following steps:
(1) rotary cutting or slicing the wood into wood veneers;
(2) drying the wood veneer processed in the step (1);
(3) coating adhesive on the wood veneer processed in the step (2);
(4) assembling the wood veneers treated in the step (3);
post-treatment:
(5) carrying out vacuum hot pressing on the plate blank treated in the step (4), wherein the hot pressing temperature is 100-120 ℃, the hot pressing time is 50-90s/mm, and the hot pressing pressure is 1-2 MPa;
(6) after the plate blank processed in the step (5) is subjected to hot pressing for a long time, removing vacuum, relieving pressure, cooling, cutting edges and sanding, and finally obtaining the plywood with high bonding strength;
wherein the final water content of the wood veneer in the step (2) is 8 +/-3% after drying treatment; the adhesive in the step (3) is urea-formaldehyde resin adhesive, and the double-side adhesive applying amount is 200-2(ii) a And (4) assembling the plate blanks in a longitudinal-transverse-longitudinal three-layer or odd-number layer assembling mode.
5. The method for vacuum compression densification of wood-based material according to claim 1, wherein the pretreatment step comprises the following steps:
(1) slicing and drying: drying the sliced veneer, namely a wooden veneer with the thickness of 1.6-1.8mm in a drying box; (2) gluing: coating the dried wood veneer with an adhesive;
(3) assembling: assembling according to the assembling mode of the laminated veneer lumber;
post-treatment:
(4) vacuum hot pressing: after the plate blank is placed in a press, a vacuum cover is closed, and the plate blank is vacuumized and hot-pressed;
(5) pressure relief: and (3) after the hot pressing time is reached, removing vacuum, finishing the hot pressing, releasing pressure, taking out the plate blank, cooling, cutting edges and sanding to obtain the structural laminated veneer lumber.
6. The method for vacuum compression densification of wood materials according to claim 5, wherein the wood veneer of step (1) is a crack-free poplar veneer, and the moisture content after drying is 10%; in the step (2), the adhesive is phenolic resin, the solid content is 65%, and the double-sided adhesive applying amount is 300g/m2(ii) a In the step (4), the hot pressing temperature is 145 ℃, the slab pressure is 1.0MPa, and the hot pressing time is 60 s/mm.
7. The method for vacuum compression densification of wood-based material according to claim 1, wherein the pretreatment step comprises the following steps:
(1) preparing materials: sawing the sawn timber to obtain sawn timber with water content of 12% and the wood material;
(2) gluing: coating adhesive on the dried sawn timber;
(3) assembling: assembling according to the assembling mode of the integrated material;
post-treatment:
(4) vacuum hot pressing: after the plate blank is placed in a press, a vacuum cover is closed, and the plate blank is vacuumized and hot-pressed;
(5) pressure relief: and (4) after the hot pressing time is reached, removing vacuum, finishing the hot pressing, releasing pressure, taking out the plate blank, cooling, cutting edges and sanding to obtain the structural laminated wood.
8. The method for vacuum compression densification of wood material according to claim 7, wherein in the step (1), the wood material is pinus sylvestris sawn timber, and in the step (2), the adhesive is resorcinol-phenol-formaldehyde copolymer resin, the solid content is 50%, and the double-sided adhesive application amount is 260g/m2(ii) a The hot pressing temperature in the step (4) is 145 ℃, the unit pressure of the plate blank is 1.0MPa, and the hot pressing time is 60 s/mm.
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| CN109591122B (en) * | 2017-12-29 | 2021-09-03 | 南京林业大学 | Method for vacuum compression and densification of wood material |
| CA3087229A1 (en) | 2017-12-29 | 2019-07-04 | Armstrong Hardwood Flooring Company | Densified wood including process for preparation |
| CN109283048A (en) * | 2018-06-27 | 2019-01-29 | 宜华生活科技股份有限公司 | A process method and device for dense wood surface |
| CN109434975A (en) * | 2018-12-18 | 2019-03-08 | 南京工业大学 | Orthogonal laminated wood integrating material characteristics of fast growing wood and building structure requirements and preparation method thereof |
| CN110472719B (en) * | 2019-08-01 | 2024-04-26 | 珠海全球时代科技有限公司 | Method for manufacturing wooden electronic tag card |
| CN112659304A (en) * | 2021-01-29 | 2021-04-16 | 云南省烟草公司文山州公司 | Preparation method of composite board taking flue-cured tobacco straw as raw material and board |
| CN114227831A (en) * | 2021-11-30 | 2022-03-25 | 苏州昆仑绿建木结构科技股份有限公司 | Manufacturing technology of high-strength laminated wood |
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| CN108177209A (en) | 2018-06-19 |
| CN108177209B (en) | 2019-03-29 |
| CN109591122A (en) | 2019-04-09 |
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