CN104985657B - Enhanced high-temperature heat treated wood and manufacturing method thereof - Google Patents

Abstract

The invention discloses an enhanced high-temperature heat-treated wood and a manufacturing method thereof. The manufacturing method includes the following steps: 1) high-temperature heat treatment: using artificial forest wood as a raw material, performing high-temperature heat treatment on the artificial forest wood to obtain heat-treated wood; 2) impregnating enhanced Treatment: impregnating the heat-treated wood obtained in step 1) into a resin adhesive to obtain an impregnated wood; 3) curing and shaping treatment: curing and shaping the impregnated wood obtained in step 2) to obtain enhanced high-temperature heat-treated wood. The manufacturing method of the invention can not only improve the mechanical strength of the wood but also improve the dimensional stability of the wood and is environmentally friendly, and the prepared enhanced high-temperature heat-treated wood uses artificial forest wood as a raw material, has high mechanical strength and excellent dimensional stability.

Description

Enhanced high-temperature heat-treated wood and its manufacturing method

technical field

The invention belongs to the category of wood function improvement in the field of wood processing, and in particular relates to an enhanced high-temperature heat-treated wood and a manufacturing method thereof.

Background technique

The basic principle of wood heat treatment is to use the temperature condition of 160-260 ℃ to treat wood for a certain period of time, the wood cell wall material will undergo pyrolysis and molecular structure recombination, and the wood components will undergo permanent chemical changes, so that the hygroscopicity of the treated wood will be reduced and the size will be stable. It is suitable for outdoor floors, outdoor decorative wall panels, garden furniture, wooden fences, etc. On the other hand, wood heat treatment will lead to a decrease in the mechanical strength and weight of the wood, which has become its main disadvantage.

The commercial application of wood heat treatment technology mainly started in European countries, but in recent years, domestic heat treatment technology and commercial application have improved significantly, and heat treatment technology or process has gradually matured. Due to the severe shortage of natural forest resources in China, some wood processing enterprises have begun to turn their attention to the development and utilization of fast-growing wood from plantation forests with rich resources. Although technology can improve its dimensional stability, if it is directly heat-treated, the strength of the wood will be further reduced, which cannot meet the use requirements well. In view of the low density and poor strength of plantation wood, which is not suitable for direct heat treatment and modification, the integrated technology of wood heat treatment and chemical reinforcement modification technology or heat treatment and physical reinforcement modification technology has been born, such as resin impregnation reinforcement technology. -Heat treatment integration technology, heat treatment-compression enhancement integration technology. For the former, the strength of the wood is significantly enhanced after resin impregnation, but the subsequent heat treatment will cause the resin to fail to a certain extent, the brittleness of the material will increase, and part of the strengthening effect has been destroyed; for the latter, the plasticity of the wood will be significantly reduced after heat treatment. , the difficulty of subsequent compression enhancement is significantly increased, and the compression treatment will not only cause the loss of wood volume to a certain extent, but also have the problem of springback after compression treatment.

Plantation forest fast-growing timber is very rich in resources in our country. Through more scientific modification treatment, seeking reasonable and efficient utilization methods to solve its strength and dimensional stability and other problems will improve the added value of products, broaden its application fields, and alleviate the seriousness of natural forest resources. Issues such as shortages are of great importance.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art, to provide an enhanced high-temperature heat-treated wood manufacturing method that can improve both the mechanical strength of wood and the dimensional stability of wood, and is environmentally friendly. Forest wood is an enhanced high-temperature heat-treated wood with high mechanical strength, excellent dimensional stability, and environmental protection.

In order to solve the problems of the technologies described above, the present invention adopts the following technical solutions:

A method for manufacturing enhanced high-temperature heat-treated wood, comprising the following steps:

1) High-temperature heat treatment: use plantation wood as raw material, perform high-temperature heat treatment on plantation wood to obtain heat-treated wood;

2) Impregnation enhancement treatment: immerse the heat-treated material obtained in step 1) in a resin adhesive to obtain an impregnated material;

3) Curing and setting treatment: the impregnated wood obtained in step 2) is subjected to curing and setting treatment to obtain enhanced high-temperature heat-treated wood.

In the above manufacturing method, preferably, the high temperature heat treatment in step 1) includes the following steps:

1.1) Primary drying: put the plantation wood in a high-temperature heat treatment tank, first raise the temperature to 100°C at a heating rate of 15°C/h-20°C/h, and then raise the temperature at a heating rate of 5°C/h-10°C/h To 130 ℃, heat preservation 1h ~ 5h;

1.2) Insulation heat treatment: heat the once-dried wood from 130°C to 160°C-260°C, the heating rate is 10°C/h-15°C/h, the holding time is 1h-4h, and the oxygen content of the wood is controlled at ≤ within 2%;

1.3) Cooling and humidity adjustment: steam spray treatment on the wood after heat preservation and heat treatment, stop the steam spray treatment when the temperature in the high-temperature heat treatment tank drops to 100°C, and leave the tank after the temperature of the wood drops to room temperature to obtain heat-treated wood.

In the above-mentioned manufacturing method, preferably, the impregnation strengthening treatment in step 2) includes the following steps:

2.1) Vacuuming: Put the heat-treated material obtained in step 1) into a dipping tank for vacuuming treatment, the vacuum degree is 0.06MPa-0.095MPa, and the holding time is 0.25h-1h;

2.2) Pressure impregnation: add resin adhesive into the impregnation tank, and perform pressure impregnation on the heat-treated material after vacuum treatment. The impregnation pressure is 0.5MPa-2.5MPa, and the impregnation time is 30min-120min;

2.3) Secondary drying: The heat-treated material after pressure impregnation is subjected to secondary drying until the final moisture content is 10% to 15%, and the impregnated material is obtained.

In the above manufacturing method, preferably, the curing and shaping treatment in step 3) includes the following steps:

3.1) Curing molding: place the impregnated material obtained in step 2) in a high-temperature heat treatment tank, raise the temperature to 105°C-130°C at a heating rate of 5°C/h-10°C/h, and keep it warm for 6h-12h;

3.2) Cooling and humidity control: Spray steaming and humidity control on the cured impregnated wood until the final moisture content is 5% to 8% to obtain enhanced high-temperature heat-treated wood.

In the above-mentioned manufacturing method, preferably, the manufacturing method further includes balancing treatment, the specific steps are: placing the enhanced high-temperature heat-treated wood obtained in step 3) in an indoor environment for 14 to 30 days in close-packed storage.

In the above-mentioned manufacturing method, preferably, the resin adhesive is a low molecular weight resin adhesive, the solid content of the low molecular weight resin adhesive is 35% to 50%, and the low molecular weight resin adhesive is The dynamic viscosity is 10MPa·s～20MPa·s. (Low molecular weight in the present invention means that the average value of viscosity average molecular weight is basically within 300-500).

In the above manufacturing method, preferably, the low molecular weight resin adhesive includes a urea-formaldehyde resin adhesive or a water-soluble phenolic resin adhesive.

In the above manufacturing method, preferably, the plantation wood is plantation fast-growing poplar or plantation fast-growing fir; the initial moisture content of the plantation wood is 12%-20%.

As a general technical idea, the present invention also provides an enhanced high-temperature heat-treated wood produced by the above-mentioned manufacturing method.

In the aforementioned enhanced high-temperature heat-treated wood, preferably, the enhanced high-temperature heat-treated wood has a density of 0.55 g/cm ³ to 0.7 g/cm ³ ;

The flexural strength of the enhanced high-temperature heat-treated wood is increased by 72.7% to 90.9%, and 84.2% to 137.5% respectively compared with the raw material and the flexural strength of the heat-treated wood obtained in step 1);

The flexural modulus of the enhanced high-temperature heat-treated wood is respectively increased by 51.7% to 78.5%, and 66.7% to 112.5% compared with the raw material and the flexural modulus of the heat-treated wood obtained in step 1);

The radial shrinkage rate of the enhanced high-temperature heat-treated wood is 33.3%-70% lower than that of the raw material;

The chord-wise shrinkage of the enhanced high-temperature heat-treated wood is 38.2%-65% lower than the chord-wise shrinkage of the raw material;

The radial swelling rate of the enhanced high-temperature heat-treated wood is 25.3%-90.6% lower than that of the raw material;

The chordwise swelling rate of the enhanced high-temperature heat-treated wood is 35.5%-90.7% lower than that of the raw material.

In the present invention, secondary drying includes natural drying and artificial drying.

Compared with the prior art, the present invention has the advantages of:

(1) The manufacturing method of the enhanced high-temperature heat-treated wood of the present invention is based on the principle that the wood is firstly subjected to high-temperature heat treatment to reduce its moisture absorption and water absorption and improve its dimensional stability, and then use low-molecular-weight resin to impregnate the heat-treated wood to enhance treatment, In order to make up for the negative impact of heat treatment on the mechanical strength, and further improve its dimensional stability, and finally through a certain temperature curing molding treatment, the resin is completely cured and forms a stable chemical bond with the wood cell wall material without loss, and releases the solidification. The free formaldehyde and free phenol that have not completely reacted in the first stage make the treated materials safer and more environmentally friendly.

(2) Compared with wood heat treatment technology, impregnation enhancement-heat treatment technology, heat treatment-compression enhancement technology, etc., the manufacturing method of the present invention solves the problem of mechanical strength reduction of heat-treated materials well. It can also avoid the problem of resin failure caused by high temperature heat treatment after impregnating resin first, and fully exert the treatment effect of resin impregnation enhancement. After treatment, the mechanical strength and dimensional stability of wood are better, and there is no rebound caused by physical compression. question.

(3) The enhanced high-temperature heat-treated wood of the present invention uses artificial forest wood as raw material, and its various properties are obviously improved after being treated by the manufacturing method of the present invention. Its density is about 0.55g/cm ³ ~ 0.7g/cm ³ , which is 57% ~ 100% higher than that of the material (ie raw material); the flexural strength is compared with the material, heat treatment material, and conventional impregnation-heat treatment method. The impregnation-heat treatment materials increased by 72.7%~90.9%, 84.2%~137.5%, 14.1%~58.3% respectively; Increased by 51.7% to 78.5%, 66.7% to 112.5%, 21.9% to 63.4%; radial and chord shrinkage (wet to dry) were respectively 33.3% to 70% and 38.2% to 65% lower than the raw material %; the radial and chord swelling rates (from dry to stable water absorption) are respectively 25.3% to 90.6% and 35.5% to 90.7% lower than those of the material.

detailed description

The following specific preferred embodiments are used to further describe and illustrate the present invention, but the protection scope of the present invention is not limited thereby.

Example:

A kind of manufacturing method of enhanced high-temperature heat-treated wood of the present invention, with plantation fast-growing poplar as raw material, comprises the following steps:

1) High temperature heat treatment:

1.1) Primary drying: put poplar wood with an initial moisture content of 12% into a high-temperature heat treatment tank, first rapidly raise the temperature to 100°C, and the heating rate is 15°C/h, so that the surface temperature of the wood is consistent with the internal temperature; then The temperature rises steadily to 130°C, the heating rate is 10°C/h, and the temperature is kept for 5 hours, so that the moisture content of the wood is reduced to about 0;

1.2) Insulation heat treatment: the once-dried poplar wood is rapidly heated from 130°C to 180°C, the heating rate is 15°C/h, the holding time is 4h, and the oxygen content is controlled within the range of less than or equal to 2%;

1.3) Cooling and humidity adjustment: After heat preservation and heat treatment, turn off the heating equipment, and spray and steam the poplar wood after heat preservation and heat treatment. When the temperature in the high temperature heat treatment tank drops to 100°C, stop the spray and steam treatment until the temperature of the wood drops to room temperature out of the tank to obtain heat-treated materials.

2) Dipping enhanced treatment:

2.1) Vacuuming: Place the heat-treated material obtained in step 1.3) in a dipping tank for vacuuming treatment with a vacuum degree of 0.095MPa and a holding time of 0.5h;

2.2) Pressure impregnation: After vacuuming, add urea-formaldehyde resin adhesive to the impregnation tank. The solid content of urea-formaldehyde resin adhesive is 35%, and the dynamic viscosity of urea-formaldehyde resin adhesive is 13MPa s. The heat-treated material after treatment is subjected to pressure impregnation treatment, the impregnation pressure is 0.8MPa, the impregnation time is 120min, and finally the pressure is released slowly to obtain the heat-treated material after pressure impregnation;

2.3) Secondary drying: place the heat-treated material after pressure impregnation in the atmospheric environment, let the water evaporate naturally for a period of time, and then perform artificial drying until the final moisture content is 15%, and the impregnated material is obtained.

3) Curing and shaping treatment:

3.1) Curing molding: Place the impregnated material obtained in step 2.3) in a high-temperature heat treatment tank, and steadily raise the temperature to 105°C at a heating rate of 5°C/h, and keep it warm for 12 hours to completely cure the resin and release the incomplete reaction in the resin of free formaldehyde;

3.2) Cooling and humidity control: After curing and forming, the cured and formed impregnated wood is subjected to spray steaming and humidity control treatment until the final moisture content is within 6%, and enhanced high-temperature heat-treated wood is obtained.

4) Balance treatment: The enhanced high-temperature heat-treated wood obtained in step 3) is placed in an indoor environment and aged for 14 days.

After testing, the enhanced high-temperature heat-treated wood manufactured by the above-mentioned method of this embodiment has a density of 0.6g/cm ³ , which is 71.4% higher than that of the raw material (that is, the material); 1.3) The obtained heat-treated material and the impregnated-heat-treated material prepared by the conventional impregnation-heat treatment method have increased by 81.8%, 92.3%, and 20.2% respectively; the flexural modulus of elasticity is 8800MPa, compared with the raw material and the heat-treated material obtained in step 1.3). The impregnation-heat treatment materials prepared by conventional impregnation-heat treatment methods increased by 57.1%, 72.1%, and 28.1% respectively; the radial shrinkage rate and chord shrinkage rate (wet material to absolute dryness) were 1.8% and 4.2%, respectively. Compared with the raw materials, it is reduced by 66.4% and 61.3%; the radial swelling rate and the chordwise swelling rate (from dry to water absorption stability) are 0.8% and 2.1% respectively, which are respectively reduced by 73.3% and 73.1% compared with the raw materials %.

The enhanced high-temperature heat-treated wood produced in this embodiment has excellent mechanical strength and dimensional stability, and can be widely used in fields such as outdoor floors and outdoor decorative structural materials.

The above descriptions are only preferred implementations of the present invention, and the scope of protection of the present invention is not limited to the above examples. All technical solutions under the idea of the present invention belong to the protection scope of the present invention. It should be pointed out that for those skilled in the art, improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims (5)

1. a kind of manufacture method of enhancement mode high-temperature thermal treatment timber, comprises the following steps：

1）High-temperature heat treatment：With artificial forest wood as raw material, high-temperature heat treatment is carried out to artificial forest wood, obtain heat-treated wood；

2）Dipping enhancement process：By step 1）Gained heat-treated wood impregnated in Resin adhesive, obtain impreg；

3）Solidifying and setting process：By step 2）Gained impreg carries out solidifying and setting process, obtains enhancement mode high-temperature thermal treatment timber；

The step 1）High-temperature heat treatment comprise the steps：

1.1）Primary drying：Artificial forest wood is placed in high-temperature heat treatment tank, first with the heating rate of 15 DEG C/h~20 DEG C/h 100 DEG C are warming up to, then 130 DEG C are warming up to the heating rate of 5 DEG C/h~10 DEG C/h, be incubated 1h~5h；

1.2）Insulation heat treatment：Timber after primary drying is warming up to into 160 DEG C~260 DEG C by 130 DEG C, heating rate is 10 DEG C/h~15 DEG C/h, temperature retention time is 1h~4h, and the oxygen content of timber is controlled in the range of≤2%；

1.3）Cooling damping：Timber after insulation heat treatment is carried out into steam-injection process, treats that temperature is down to 100 in high-temperature heat treatment tank DEG C when, stop steam-injection process, go out tank after Wood temperature is down to room temperature, obtain heat-treated wood；

The step 2）Dipping enhancement process comprise the steps：

2.1）Evacuation：By step 1）Gained heat-treated wood is placed in impregnating autoclave and carries out evacuation process, and vacuum is 0.06MPa ~0.095MPa, the dwell time is 0.25h~1h；

2.2）Impregnating by pressure：Resin adhesive is added into impregnating autoclave, pressurization leaching is carried out to the heat-treated wood after evacuation process Stain process, impregnation pressure is 0.5MPa~2.5MPa, and dip time is 30min~120min；

2.3）Redrying：Heat-treated wood after impregnating by pressure is carried out into redrying, is 10%~15% to final moisture content, obtained Impreg；

The step 3）Solidifying and setting process comprise the steps：

3.1）Curing molding：By step 2）Gained impreg is placed in high-temperature heat treatment tank, with the intensification speed of 5 DEG C/h~10 DEG C/h Rate is warming up to 105 DEG C~130 DEG C, is incubated 6h~12h；

3.2）Cooling damping：Steam-injection conditioning is carried out to the impreg after curing molding, is 5%~8% to final moisture content, obtained Enhancement mode high-temperature thermal treatment timber；

The Resin adhesive is low-molecular-weight resin adhesive, the solid content of the low-molecular-weight resin adhesive is 35%~ 50%, the dynamic viscosity of the low-molecular-weight resin adhesive is 10mPas~20mPas；

The low-molecular-weight resin adhesive includes urea-formaldehyde resin adhesive or the glutinous agent of water-soluble phenolic resin adhesive.

2. manufacture method according to claim 1, it is characterised in that the manufacture method also includes Balance Treatment, specifically Step is：By step 3）Mi Dui displays 14 days~30 days in gained enhancement mode high-temperature thermal treatment timber environment disposed within.

3. manufacture method according to claim 1, it is characterised in that the artificial forest wood be artificial forest quick growth poplar wood or Artificial forest fast-growing Chinese fir；The first moisture content of the artificial forest wood is 12%~20%.

4. enhancement mode high-temperature thermal treatment timber obtained in a kind of manufacture method as any one of claims 1 to 3.

5. enhancement mode high-temperature thermal treatment timber according to claim 4, it is characterised in that the enhancement mode high-temperature heat treatment The density of timber is 0.55g/cm³~0.7g/cm³；

The bending strength of the enhancement mode high-temperature thermal treatment timber is compared to the raw material, the step 1）The heat treatment for obtaining The bending strength of material is respectively increased 72.7%~90.9%, 84.2%~137.5%；

The Deflection Modulus of Elasticity of the enhancement mode high-temperature thermal treatment timber is compared to the raw material, the step 1）The heat for obtaining The Deflection Modulus of Elasticity for processing material is respectively increased 51.7%~78.5%, 66.7%~112.5%；

The radial shrinkage rate of the enhancement mode high-temperature thermal treatment timber reduces by 33.3% compared to the radial shrinkage rate of the raw material ~70%；

The Chordwise shrinkage of the enhancement mode high-temperature thermal treatment timber reduces by 38.2% compared to the Chordwise shrinkage of the raw material ~65%；

The radial direction bulking factor of the enhancement mode high-temperature thermal treatment timber reduces by 25.3% compared to the radial direction bulking factor of the raw material ~90.6%；

The tangential bulking factor of the enhancement mode high-temperature thermal treatment timber reduces by 35.5% compared to the tangential bulking factor of the raw material ~90.7%.