CN115256577A

CN115256577A - Method for improving dimensional stability and strength of wood

Info

Publication number: CN115256577A
Application number: CN202210954456.6A
Authority: CN
Inventors: 解林坤; 唐唯; 蹇玉兰; 徐开蒙; 万辉
Original assignee: Southwest Forestry University
Current assignee: Southwest Forestry University
Priority date: 2022-08-10
Filing date: 2022-08-10
Publication date: 2022-11-01

Abstract

The invention discloses a method for improving the dimensional stability and strength of wood, which comprises the following steps: s1: placing the dried wood into a vacuum pressurization impregnation tank, sealing, vacuumizing the vacuum pressurization impregnation tank to-0.05 MPa to-0.098 MPa, and keeping for 20min to 40min; s2: sucking the prepared impregnation liquid into a vacuum pressurization impregnation tank, keeping for 2-4 h to fully swell the wood, and then pressurizing to 0.5-0.8 MPa, and keeping for 6-24 h. The invention combines the vacuum pressure impregnation technology and the Chemical Vapor Deposition (CVD) technology to treat the wood, has obvious effect, simple method, uncomplicated device, easily obtained raw materials, low cost and convenient industrial production.

Description

Method for improving dimensional stability and strength of wood

Technical Field

The invention relates to a method for improving the stability of wood, in particular to a method for improving the dimensional stability and strength of wood, and belongs to the technical field of wood modification.

Background

As a natural renewable resource, wood has the advantages of easy processing, beautiful texture, high strength-to-weight ratio, biodegradability and the like, and is widely applied to the fields of indoor and outdoor buildings, decorations, furniture and the like. However, the main components of the wood contain a large amount of hygroscopic hydroxyl groups and the inherent multi-scale pore structure provides enough hygroscopic and permeable channels for liquid or vapor, so that the wood is easy to generate the defects of dry shrinkage, wet swelling, unstable size, reduced mechanical strength and the like, and the expansion of the life cycle and the application range of the wood is seriously influenced. The method is inspired by the super-hydrophobic phenomenon in nature, and the wood is subjected to super-hydrophobic treatment, so that the number of hydroxyl groups in the wood is reduced, and the wood surface can be endowed with the functions of water resistance, mildew resistance, self-cleaning and the like.

At present, a plurality of methods for preparing the super-hydrophobic wood exist, such as a sol-gel method, a hydrothermal method, a layer-by-layer self-assembly method, a spraying method, plasma treatment, surface graft copolymerization and the like. Although a large number of artificial superhydrophobic timbers inspired by natural micro/nanostructures have been developed, most of the methods focus only on surface modification, and cannot get rid of introducing inorganic nanomaterials of SiO, which are commonly used in the preparation of superhydrophobic surfaces ₂ 、TiO ₂ And ZnO and the like are used for constructing a micro-nano coarse structure required by a super-hydrophobic coating, and meanwhile, the influence of super-hydrophobic treatment on the dimensional stability and the mechanical property change caused by wood water absorption is rarely studied. Furthermore, superhydrophobic wood is generally water repellent, but the superhydrophobic coating on its surface does not prevent water vapor in the air from penetrating into the wood. On the other hand, superhydrophobicity can be achieved on low free energy surfaces, but fluorination treatments are typically used to reduce surface energy. It is known that the C-F bond in the fluorine-containing compound has extremely high chemical bond energy and is not easy to degrade after being subjected to heat, light, microbial action and animal metabolism, so that the fluorine-containing compound has a long elimination half-life period in wild animals and human beings, thereby causing toxicological problems and having potential harm to the environment and human health. At present, the methodDriven by ecological protection and health awareness, development of nontoxic and green chemical modification methods is receiving attention from many scholars. Therefore, developing a method for preparing super-hydrophobic wood with low cost, environmental protection and capability of improving the dimensional stability and mechanical properties of wood becomes a technical problem to be solved urgently by researchers in the field.

Disclosure of Invention

The present invention is directed to a method for improving the dimensional stability and strength of wood, so as to solve the above problems in the prior art.

In order to achieve the purpose, the invention provides the following technical scheme: the method comprises the following steps:

s1: placing the dried wood into a vacuum pressurization impregnation tank, sealing, vacuumizing the vacuum pressurization impregnation tank to-0.05 MPa to-0.098 MPa, and keeping for 20min to 40min;

s2: sucking the prepared impregnation liquid into a vacuum pressurization impregnation tank, continuously keeping the vacuum degree for 2 to 4 hours to fully swell the wood, then pressurizing to 0.5 to 0.8MPa, and keeping the pressure for 6 to 24 hours;

s3: releasing the pressure, taking out the impregnated wood, and naturally drying the impregnated wood in the environment;

s4: putting the naturally air-dried wood in the step S3 and two open glass vials containing chemical reagents into a glass dryer by using a functional monomer methyltrimethoxysilane through a chemical vapor deposition method, sealing, and carrying out vapor deposition reaction in an oven at a certain temperature for a period of time;

s5: and taking the test piece out of the glass dryer, independently drying the test piece in an oven, and finally sealing and storing the test piece to obtain the super-hydrophobic wood.

As a preferred technical solution of the present invention, the specific preparation method of the dried wood in the step S1 is: and (3) performing surface sanding treatment on the sawed wood with the required size by using sand paper (240-400 meshes), blowing off dust on the surface by using compressed air, drying in an oven at 103 ℃ for 2-8 h, and finally sealing and storing.

As a preferred technical solution of the present invention, the preparation method of the immersion liquid in step S2 comprises: before the impregnation liquid is sucked into a vacuum pressure impregnation tank, mixing methyltrimethoxysilane and an ethanol solution (absolute ethanol and distilled water are prepared according to a volume ratio of 9: ethanol solution = n:1, wherein n is 0.1, 0.5, 1, 2, 4.

As a preferable technical solution of the present invention, the natural air drying time in the step S3 is 7 to 14 days.

As a preferred technical solution of the present invention, the chemical vapor deposition method in step S4 specifically includes the following steps:

the first step is as follows: adding a certain volume of methyltrimethoxysilane into one open glass vial, adding a certain volume of methanol into the other open glass vial, and adding ammonia water serving as a catalyst into a vial containing methanol;

the second step is that: putting the treated and air-dried wood and two open glass vials into a glass dryer, sealing the glass dryer with vaseline, and performing vapor deposition reaction in an oven at a certain temperature for a certain time.

As a preferred technical scheme of the invention, the open glass vial containing the methanol and the ammonia water is arranged at the lower layer, the open glass vial containing the methyltrimethoxysilane is arranged at the upper layer, the wood sample is arranged at the upper layer and distributed around the glass vial, the two glass vials are positioned at the center and vertically distributed up and down, the oven temperature of the chemical vapor deposition reaction is 80-120 ℃, the reaction time is 3-12 hours, and the volume ratio of the raw materials of the chemical vapor deposition reaction is methyltrimethoxysilane: methanol: ammonia =2: n:1, wherein n is 0.5, 1, 3, 5 and 9, the mass concentration of methyltrimethoxysilane is 98-99.8%, methanol is analytically pure, and the mass concentration of ammonia water is 10-28%.

As a preferable technical scheme of the invention, the single drying temperature of the step S5 is 80-105 ℃, and the drying time is 2-12 hours.

The invention is a preferable technical scheme, which is applied to the method for improving the dimensional stability and the strength of the wood as claimed in any one of claims 1 to 7, and comprises a vacuum pump, a positive and negative pressure gauge, a power supply controller, a CVD heating oven, a CVD generator, a pressure pump, an impregnation liquid storage bottle, an impregnation tank, a glass small bottle and a valve, wherein the impregnation tank (8) comprises four interfaces which are respectively connected with the vacuum pump, the pressure pump, the impregnation liquid storage bottle (7), an exhaust valve and a safety valve, the wood test piece (B) is taken out and dried under natural conditions after being subjected to vacuum pressure impregnation treatment in the impregnation tank, then the wood test piece is put into the CVD generator (5) together with an open glass small bottle (9) containing methanol and ammonia water and an open glass small bottle (10) containing methyltrimethoxysilane and is transferred into the CVD heating oven for continuous chemical vapor deposition treatment, and the wood test piece is taken out and is dried in the oven separately after the deposition treatment is finished and is packaged in a sealing mode. The CVD heating oven, the vacuum pump and the pressure pump are all electrically connected with the power supply controller.

As a preferred technical scheme of the invention, the interior of the CVD generator is of an upper layer structure and a lower layer structure which are separated by a round stainless steel net, and both a vacuum pump and a pressure pump can adjust the pressure.

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

1) The method has the advantages of obvious wood treatment effect by combining the vacuum pressurization impregnation technology and the chemical vapor deposition technology, simple method, uncomplicated device, easily obtained raw materials, low cost and convenience for industrial production.

2) The static water contact angle of the super-hydrophobic wood surface is 150-153 degrees, the rolling angle is less than 10 degrees, and the super-hydrophobic wood surface has excellent hydrophobic property and good self-cleaning property.

3) The preparation principle of the super-hydrophobic wood is that methyltrimethoxysilane is easy to undergo hydrolysis reaction after meeting water to generate methyltrimethoxysilane, the methyltrimethoxysilane and wood are further subjected to condensation reaction to generate polysiloxane with hydrophobicity (the reaction mechanism is shown in figure 7), the product is safe and environment-friendly, non-toxic and harmless, the wood property is not influenced, and the wood mechanical strength is enhancedthe-OH on the silanol prepolymer and the residual-OH in the wood will gradually be replaced by non-polar-CH ₃ Instead, a branched macromolecular polymer with low surface energy is formed, so that an excellent super-hydrophobic effect is generated, and most importantly, methanol is used as a solvent in the CVD deposition process to play a role in delaying the condensation reaction to a certain extent, so that a polysiloxane skeleton slowly grows and is fully polymerized on wood. However, if the methanol content is too high, the siloxane concentration is low, and the reaction is insufficient, thereby affecting the hydrophobic effect.

Drawings

FIG. 1 is a diagram of an experimental apparatus according to the present invention;

FIG. 2 is a drawing of the effect of the dewatering of the chord section of the super-hydrophobic wood according to the present invention;

FIG. 3 is a Scanning Electron Microscope (SEM) of a chord section of a superhydrophobic wood in an embodiment of the invention;

FIG. 4 is a Fourier transform Infrared Spectroscopy (FTIR) of a superhydrophobic wood surface in an example of the invention;

FIG. 5 is an X-ray photoelectron spectroscopy (XPS) of a chord section of a superhydrophobic wood according to an embodiment of the present invention;

FIG. 6 is a photograph of an underwater silver mirror phenomenon of a superhydrophobic wood in an embodiment of the invention;

FIG. 7 is the condensation reaction mechanism of methyl trimethoxy silane and wood.

In the figure: 1. a vacuum pump; 2. a positive and negative pressure gauge; 3. a power supply controller; 4. a CVD heating oven; 5. a CVD generator; 6. a pressure pump; 7. a steeping liquor storage bottle; 8. an impregnation tank; 9-10, glass vials; 11-14 and a valve.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the 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.

Referring to fig. 1-7, the present invention provides a method for improving the dimensional stability and strength of wood, which comprises the following steps:

as shown in fig. 1-7, the method comprises the following steps:

s3: releasing the pressure, taking out the impregnated wood, and naturally drying the impregnated wood in the air under the environmental condition;

s4: putting the naturally air-dried wood in the step S3 and two open glass vials containing chemical reagents into a glass drier through a chemical vapor deposition method by using a functional monomer methyltrimethoxysilane, sealing the glass drier, and putting the sealed glass drier into an oven at a certain temperature for a certain period of time through vapor deposition reaction;

s5: and taking the test piece out of the glass dryer, placing the test piece in an oven for independent drying, and finally sealing and storing to obtain the super-hydrophobic wood.

The specific preparation method of the dried wood in the step S1 comprises the following steps: performing surface sanding treatment on the sawed wood with the required size by using sand paper (240-400 meshes), blowing off dust on the surface by using compressed air, drying in an oven at 103 ℃ for 2-8 h, and finally sealing and storing;

the preparation method of the impregnation liquid in the step S2 comprises the following steps: before the impregnation liquid is sucked into a vacuum pressure impregnation tank, mixing methyltrimethoxysilane and an ethanol solution (absolute ethanol and distilled water are prepared according to a volume ratio of 9: ethanol solution = n:1, wherein n is 0.1, 0.5, 1, 2, 4;

the natural air drying time in the step S3 is 7-14 days;

the chemical vapor deposition method in step S4 specifically includes the steps of:

the second step is that: putting the treated and air-dried wood and two open glass vials into a glass dryer, sealing the glass dryer with vaseline, and performing vapor deposition reaction in an oven at a certain temperature for a certain time;

placing an open glass vial containing methanol and ammonia water at the lower layer, placing an open glass vial containing methyltrimethoxysilane at the upper layer, placing a wood sample at the upper layer and distributing around the glass vial, wherein the two glass vials are positioned at the center and vertically distributed, the oven temperature of the chemical vapor deposition reaction is 80-120 ℃, the reaction time is 3-12 hours, and the volume ratio of the raw materials of the chemical vapor deposition reaction is methyltrimethoxysilane: methanol: ammonia =2: n:1, wherein n is 0.5, 1, 3, 5 and 9, the mass concentration of methyltrimethoxysilane is 98-99.8%, methanol is analytically pure, and the mass concentration of ammonia water is 10-28%.

The single drying temperature of the step S5 is 80-105 ℃, and the drying time is 2-12 hours.

The equipment for improving the dimensional stability and strength of the wood comprises a vacuum pump 1, a positive and negative pressure gauge 2, a power supply controller 3, a CVD heating oven 4, a CVD generator 5, a pressure pump 6, a dipping solution storage bottle 7, a dipping tank 8, a glass small bottle 9, a glass small bottle 10, a valve 11, a valve 12, a valve 13 and a valve 14, wherein the dipping tank (8) comprises four interfaces which are respectively connected with the vacuum pump 1 and the pressure pump 6, the dipping solution storage bottle (7), an exhaust valve and a safety valve, after the wood test piece (B) is subjected to vacuum pressure dipping treatment in the dipping tank 8, the wood test piece is taken out and dried under natural conditions, the wood test piece, an open glass small bottle (9) containing methanol and ammonia water and an open glass small bottle (10) containing methyltrimethoxysilane are placed into the CVD generator (5) together, chemical vapor deposition treatment is continuously carried out in the CVD heating oven 4, and the wood test piece is taken out and dried in the oven 4 separately and then is packaged in a sealing mode. The CVD heating oven 4, the vacuum pump 1 and the pressure pump 6 are all electrically connected with the power controller 3. The CVD generator 5 is internally provided with an upper layer and a lower layer which are separated by a circular stainless steel net, and the vacuum pump 1 and the pressure pump 6 can adjust pressure.

The equipment comprises the following specific steps:

(1) Dipping treatment: firstly, placing a wood test piece into a dipping tank 8, sealing the device, then opening a valve 11, starting a vacuum pump to vacuum (negative pressure state) for a certain time, opening the valve 12, sucking a dipping solution into the dipping tank by utilizing the atmospheric pressure difference, closing the valve 12, and closing the valve 11 after maintaining the vacuum degree to be stable;

(2) And (3) pressurization treatment: after vacuum impregnation for a certain time, starting the pressure pump 6, opening the valve 13, pressurizing to a certain pressure, and closing the valve 13;

(3) Pressure relief: after the pressure impregnation treatment is carried out for a certain time, the valve 14 is opened, the pressure is relieved, and then the wood test piece is taken out and air-dried for a certain time under indoor natural conditions.

(4) CVD reaction: the dip-treated and naturally air-dried wood was placed in a CVD generator with two open glass vials, one containing methyltrimethoxysilane and the other containing both ammonia and methanol. Sealing the CVD generator and transferring the CVD generator to a CVD heating oven with a preset temperature for carrying out vapor deposition reaction for a certain time;

(5) And after the CVD reaction is finished, taking out the wood test piece, independently drying in an oven 4, and sealing and packaging.

Examples

Using poplar (Populus) as material, firstly processing it into 20X 20mm ³ The surface of the sample (2) was polished with 280-mesh sandpaper, and after removing dust from the surface with compressed air, the sample was dried in an oven at 103 ℃ for 3 hours.

Step 1: vacuum pressure impregnation: placing the test piece into a vacuum pressurization impregnation tank, sealing the device, vacuumizing to-0.098 MPa, maintaining for 30min, sucking the prepared impregnation liquid, maintaining for 3h under the vacuum degree to fully swell the wood, and pressurizing to 0.6MPa for 8h. After that, the impregnated specimen was taken out and placed in an indoor air environment to be naturally dried for 10d, to obtain a hydrophobic wood. Wherein the preparation of the impregnation liquid comprises the following steps: before the impregnation liquid is sucked into a vacuum pressurization impregnation tank, methyltrimethoxysilane and an ethanol solution (anhydrous ethanol and distilled water are prepared according to a volume ratio of 9: methyltrimethoxysilane in ethanol solution = 1.

Step 2: in a typical manufacturing process, 2mL of methyltrimethoxysilane was added to one open glass vial, 3mL of methanol was added to the other open glass vial, 1mL of ammonia was used as a catalyst, which was added to the glass vial containing methanol, three test pieces were placed in a glass dryer together with two open glass vials (the open glass vial containing methyltrimethoxysilane was placed on top, the wood sample was placed on top and distributed around the glass vial, and the two glass vials were centered and vertically distributed up and down), the glass dryer was sealed with petrolatum and electric tape and placed in an oven at a temperature of 103 ℃ for 5h to perform the vapor deposition reaction, after which the test pieces were removed from the glass dryer and were continuously dried in the oven at 103 ℃ for 3h individually to obtain a superhydrophobic wood.

The hydrophobic effect and Scanning Electron Microscope (SEM) result of the super-hydrophobic modified poplar chord section prepared by the method are respectively shown in fig. 2 and fig. 3, the fourier transform infrared spectroscopy (FTIR) result of the poplar surface before and after super-hydrophobic modification is shown in fig. 4, the X-ray photoelectron spectroscopy (XPS) result of the poplar chord section before and after super-hydrophobic modification is shown in fig. 5, the underwater silver mirror phenomenon photo of the super-hydrophobic wood is shown in fig. 6, and the prepared super-hydrophobic wood has the following properties:

(1) The static water contact angles of three sections (cross section, diameter section and chord section) of the super-hydrophobic modified poplar are all larger than 150 degrees (the test water drop is 5 mu L), the rolling angles are smaller than 10 degrees (the test water drop is 10 mu L), and the surface free energies of the three sections are all lower than 4mJ/m ² 。

(2) Compared with the original poplar (the contact angle values of 5 mu L of water drops on the cross section, the diameter section and the chord section are respectively and rapidly reduced to 0 ℃ within 10s, 40s and 20 s), after the 5 mu L of water drops are placed on the surface of the super-hydrophobic modified wood for 300s, the static water contact angles of the three sections are all larger than 150 ℃ and show perfect spherical water drops, the change rate of the water contact angle is only 0.8-1.1%, the permeation phenomenon hardly occurs, and the excellent waterproof permeability is shown.

(3) Once immersed in water, the superhydrophobic wood surface looked like a silver mirror, forming a Cassie-Baxter wet state (as shown in fig. 6). After soaking in distilled water for 24h, compared with the original poplar (the water absorption is 116.3%), the water absorption of the super-hydrophobic wood is reduced to 23.5%, the waterproof rate reaches 79.8%, and the water absorption dimensional stability (ASE) is improved to 56.5%. In addition, in order to simulate the moisture absorption process of wood under natural environmental conditions, when the sample is exposed for 24 hours under the conditions that the temperature is 20 ℃ and the Relative Humidity (RH) is 85%, compared with the original poplar (the moisture absorption rate is 14.3%), the moisture absorption rate of the super-hydrophobic wood is reduced to 9.5%, the moisture prevention rate of the super-hydrophobic wood reaches 33.6%, and the moisture absorption dimensional stability (ASE) of the super-hydrophobic wood is improved to 40.6%.

(4) The 3M600Scotch transparent adhesive tape (adhesive force to steel: 440N/mm) is lightly adhered to the surface of the super-hydrophobic wood, after a weight of 200g is applied to the surface of the super-hydrophobic wood for compaction, the adhesive tape is torn off for one test, when the test times reach 240 times, the static water contact angles of the three sections are all larger than 150 degrees, the rolling angle reduction is smaller than 4 degrees, the super-hydrophobic wood still has good super-hydrophobic property, and the super-hydrophobic wood surface has good anti-adhesive tape stripping property.

(5) The test surface of the superhydrophobic wood was rubbed back and forth on 1000 grit sandpaper for 20cm (40 cm total friction distance per cycle) under a 200g weight load, which was defined as one abrasion cycle. After 6 wear cycles, the water contact angles of the transverse section, the radial section and the chord section are respectively reduced to 140 degrees, 136.5 degrees and 131.8 degrees, and the super-hydrophobic wood still has good hydrophobicity and can meet the general requirements in daily life, which shows that the super-hydrophobic wood has good mechanical wear resistance.

(6) The contact angles of water drops with different pH values are measured to evaluate the acid and alkali resistance of the super-hydrophobic wood, and the results show that the static contact angles of the water drops with different pH values on three sections of the super-hydrophobic wood are all higher than 150 degrees, and the sliding angle is smaller than 10 degrees, which indicates that the surface of the super-hydrophobic wood has good acid and alkali resistance; further, the water contact angle after immersion in each chemical agent (HCl of pH =1, naOH of pH =13, toluene, acetone, N-hexane, ethanol, and a single solution of N, N-dimethylformamide) for 24 hours was maintained at 150 ° or more, the sliding angle was less than 10 °, and durability against damage by each chemical agent was exhibited.

(7) The sample was put into distilled water, collected under ultrasonic waves (40 kHz frequency, 100W) for 1 hour per vibration and dried (3 hours at 103 ℃), and then the contact angle and the rolling angle were measured, which is defined as one cycle. After 6 cycles, the water contact angles of the three sections of the super-hydrophobic wood are all kept above 150 degrees, and the rolling angle reduction is below 3 degrees, which fully shows that the methyltrimethoxysilane is connected with the wood substrate by a covalent bond and is firmly bonded on the wood substrate.

(8) The sample was exposed to an ultraviolet aging test chamber (irradiation intensity of 0.77W/m) ² The radiation wavelength is 340nm, the blackboard temperature is 50 ℃), after ultraviolet aging treatment for 168 hours, the contact angle value of water with three sections is still kept above 150 degrees, and the rolling angle reduction is less than 4 degrees, which proves that the super-hydrophobic wood has good ultraviolet aging resistance. In addition, after 168 hours of ultraviolet aging, the total color difference (delta E) of the chord section of the super-hydrophobic wood is only 2.25, but the delta E value of the control wood is as high as 13.33, which shows that the color change of the control wood is very obvious under the same aging condition, and also proves that the modified wood has stronger ultraviolet aging resistance.

(9) The grain compressive strength of the original wood and the super-hydrophobic wood is respectively 27.3MPa and 36.9MPa, and compared with a control material, the grain compressive strength is improved by 35.2% after the super-hydrophobic modification treatment by using methyltrimethoxysilane; the radial compressive strength of the super-hydrophobic wood is 7.0MPa, and is improved by 40.6 percent compared with 5.0MPa of untreated wood; the chordwise compressive strength of the untreated poplar is 3.4MPa, the chordwise compressive strength of the superhydrophobic treated poplar is 4.1MPa, the improvement is 20.7%, and in addition, the superhydrophobic wood also has excellent thermal stability, stain resistance and self-cleaning performance.

In the description of the present invention, it is to be understood that the indicated orientations or positional relationships are based on the orientations or positional relationships shown in the drawings, which are merely for convenience in describing the present invention and for simplicity in description, and are not intended to indicate or imply that the indicated devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.

In the present invention, unless otherwise explicitly specified or limited, for example, it may be fixedly attached, detachably attached, or integrated; can be mechanically or electrically connected; the terms may be directly connected or indirectly connected through an intermediate agent, and may be used for communicating the inside of two elements or interacting relation of two elements, unless otherwise specifically defined, and the specific meaning of the terms in the present invention can be understood by those skilled in the art according to specific situations.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. A method for improving the dimensional stability and strength of wood is characterized by comprising the following steps:

s1: putting the dried wood into a vacuum pressurization impregnation tank, sealing, pumping the vacuum pressurization impregnation tank to a vacuum degree of-0.05 MPa to-0.098 MPa, and keeping for 20min to 40min;

s4: placing the naturally air-dried wood in the step S3 and two open glass vials containing chemical reagents into a glass dryer through a chemical vapor deposition method by using a functional monomer methyltrimethoxysilane, sealing the glass dryer, and placing the sealed glass dryer into an oven at a certain temperature for reacting for a period of time;

2. A method of increasing the dimensional stability and strength of wood according to claim 1 wherein: the specific preparation method of the dried wood in the step S1 comprises the following steps: and (3) performing surface sanding treatment on the sawed wood with the required size by using sand paper (240-400 meshes), blowing off dust on the surface by using compressed air, drying in an oven at 103 ℃ for 2-8 h, and finally sealing and storing.

3. The method for improving the dimensional stability and strength of wood according to claim 1, wherein the method comprises the following steps: the preparation method of the impregnation liquid in the step S2 comprises the following steps: before the impregnation liquid is sucked into a vacuum pressurization impregnation tank, mixing methyltrimethoxysilane and an ethanol solution (anhydrous ethanol and distilled water are configured according to a volume ratio of 9: ethanol solution = n:1, wherein n is 0.1, 0.5, 1, 2, 4.

4. A method of increasing the dimensional stability and strength of wood according to claim 1 wherein: and the natural air drying time in the step S3 is 7-14 days.

5. A method of increasing the dimensional stability and strength of wood according to claim 1 wherein: the chemical vapor deposition method in the step S4 specifically includes the steps of:

the second step is that: putting the treated and air-dried wood and two open glass vials into a glass dryer, sealing the glass dryer by vaseline, and then putting the glass dryer into an oven at a certain temperature for a certain time for vapor deposition reaction.

6. A method of improving the dimensional stability and strength of wood according to claim 5 wherein: the open glass bottle containing the methanol and the ammonia water is arranged on the lower layer, the open glass bottle containing the methyltrimethoxysilane is arranged on the upper layer, the wood sample is arranged on the upper layer and distributed around the glass bottle, the two glass bottles are positioned in the center and vertically distributed, the heating temperature of an oven for the chemical vapor deposition reaction is 80-120 ℃, the reaction time is 3-12 hours, and the volume ratio of the raw materials for the chemical vapor deposition reaction is methyltrimethoxysilane: methanol: ammonia =2: n:1, wherein n is 0.5, 1, 3, 5 and 9, the mass concentration of the methyltrimethoxysilane is 98-99.8 percent, the methanol is analytically pure, and the mass concentration of the ammonia water is 10-28 percent.

7. The method for improving the dimensional stability and strength of wood according to claim 1, wherein the method comprises the following steps: the single drying temperature of the step S5 is 80-105 ℃, and the drying time is 2-12 hours.

8. The utility model provides an improve equipment of timber dimensional stability and intensity which characterized in that: the method for improving the dimensional stability and strength of the wood as claimed in any one of claims 1 to 7, comprising a vacuum pump (1), a positive pressure gauge and a negative pressure gauge (2), a power controller (3), a CVD heating oven (4), a CVD generator (5), a pressure pump (6), a dipping solution storage bottle (7), a dipping tank (8), a small glass bottle (9), a small glass bottle (10) and valves (11-14), wherein the dipping tank (8) comprises four interfaces which are respectively connected with the vacuum pump (1) and the pressure pump (6), the dipping solution storage bottle (7), an exhaust valve and a safety valve, the wood sample (B) is taken out of the dipping tank (8) for vacuum pressure treatment, air-dried under natural conditions, placed into the CVD generator (5) together with an open glass (9) containing methanol and ammonia water and an open glass bottle (10) containing methyltrimethoxysilane and transferred to the CVD heating oven (4) for chemical vapor deposition treatment, and the wood is taken out of the test sample and then independently dried in the oven (4) and then sealed packaging. Wherein the CVD heating oven (4), the vacuum pump (1) and the pressure pump (6) are electrically connected with the power controller (3).

9. The apparatus for improving dimensional stability and strength of wood according to claim 8, wherein: the CVD generator (5) is a device with sealing performance, such as a glass dryer and the like, the interior of the CVD generator is of an upper layer structure and a lower layer structure, the CVD generator is separated by a round stainless steel net, and the vacuum pump (1) and the pressure pump (6) can adjust pressure.