JPH04336203A - Manufacture of modified lumber - Google Patents

Abstract

PURPOSE:To provide a lumber modifying method capable of improving simply the dimensional stability, durability and mechanical property of lumber without the risk of losing the wood feelings of lumber raw material. CONSTITUTION:At first, with respect to lumber, either liquid A or B of phenol monomer A or water solution and hexamethylenetetramine water solution B is injected, following this, other solution except the A, B is injected therein so as to uniformly dispersion-fixing a complex of phenol-hexamethylenetetramine into the lumber structure, and thereafter subjected to heat-reaction and heat- hardening.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing modified wood. Specifically, the present invention relates to a method for producing modified wood that imparts dimensional stability, decay resistance, mechanical properties, etc. to wood used in civil engineering, building materials, railways, etc.

0002

BACKGROUND OF THE INVENTION Hitherto, wood has been used in various fields depending on its characteristics, but its use has been limited to fields that require water resistance, decay resistance, mechanical properties, etc.

[0003] As a method to improve this drawback, there is a method in which a veneer is impregnated with a low molecular weight resol type phenolic resin (hereinafter referred to as resol), dried, laminated, and hot pressed at high temperature and pressure to obtain a cured laminate. There are methods such as injecting resin into the material and heat-treating it at high temperature to obtain a resin-injected material, but the method described above to obtain a cured laminate is the most common phenol impregnation method, and the resin-injected method is rarely used. It has not been. Further, novolac type phenolic resin (hereinafter referred to as novolac) does not harden by itself and is therefore not used for modifying wood.

Furthermore, in the prior art, it is necessary to extremely reduce the viscosity of the resol in order to speed up the impregnation rate, and therefore, it is necessary to add an alkaline substance such as caustic soda to the water-soluble low-molecular-weight resol to further increase the water dilution rate. , a method of diluting with an organic solvent such as methyl alcohol is used. In this case, in the curing lamination method, the molecular weight of the resol used is small, and the curing reaction in the post-treatment takes time. However, there was a problem in that the feel of the wood surface of the wood material was lost.

[0005] In addition, the resin injection treatment method involves heating the solution in order to increase the impregnation efficiency, so the solution changes significantly over time, making it difficult to reuse the solution once used. In this case, there are major economic problems such as the high cost of solvent recovery treatment, and the resin injection treatment method is not often used. Furthermore, there is also the problem of coloring due to alkaline substances, which limits the field of use.

[0006]

[Problems to be Solved by the Invention] Therefore, an object of the present invention is to easily improve the dimensional stability, decay resistance, mechanical properties, etc. of wood without losing the feel of the wood texture of raw wood. The objective is to provide a method for modifying wood that makes it possible.

[0007]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present inventor has conducted extensive research, and instead of using a pre-condensed resol, the inventors have developed a novolac-type phenolic resin (hereinafter referred to as After dispersing and fixing a resinous and curable substance capable of producing novolak (referred to as novolac), a resinous reaction is carried out within the wood to produce heat-curable novolak, and then a curing reaction is subsequently carried out. We discovered that the above problems could be solved all at once by
The invention has been completed.

That is, in the present invention, a solution of either (A) or (B) of (A) a phenol monomer or its aqueous solution and (B) an aqueous hexamethylenetetramine solution is first injected into wood, and then (A) is injected into the wood. ) After the phenol-hexamethylenetetramine complex was uniformly dispersed and fixed in the wood structure by injecting the other solution of (B), it was heated to react to form a phenol resin, and further heated to produce a phenol resin. This is a method for producing modified wood characterized by curing a phenolic resin.

The present invention will be explained in detail below. First, the phenolic monomer, which is the raw material (A) used in the present invention, is a monomer such as phenol, cresol, xylenol, etc., and these monomers are used alone or in a mixture. When used, the monomer may be heated to 50 to 70°C to form a solution, or may be used as a 1 to 99% by weight aqueous solution, but preferably 100% monomer or
It is used as a 50-99% by weight aqueous solution.

Next, a hexamethylenetetramine aqueous solution (hereinafter referred to as hexamine aqueous solution), which is the raw material (B) used in the present invention, is prepared by dissolving hexamethylenetetramine (hereinafter referred to as hexamine) in water and having a concentration of 1 to 1. 20% by weight
It is preferably used as an aqueous solution of 10 to 15
It is used as a wt% aqueous solution. The concentration of the solution used is related to the resin impregnation rate in the wood, and is appropriately determined depending on the predetermined impregnation rate.

Next, the reaction curing of the present invention uses hexamine as a reactive formalin source and curing agent, so ammonia generated during the decomposition reaction of hexamine acts as a catalyst for reaction curing, and it can be carried out without a catalyst. , alkali metal salts such as caustic soda and slaked lime for the purpose of shortening curing time,
Compounds commonly used in phenolic resin condensation reactions, such as acidic compounds such as hydrochloric acid and oxalic acid, are used as reaction catalysts in an amount of 0.01 to 2% by weight, preferably 0.05 to 1% by weight, based on the phenolic monomer. You can also. If the amount of catalyst is large, the curing speed will be extremely fast, but there will be problems such as deterioration and discoloration of the wood due to the residual catalyst.

[0012] The method for producing modified wood according to the present invention first comprises (A) a phenolic monomer or an aqueous solution thereof;
Alternatively, (B) either (A) or (B) of the hexamine aqueous solution is injected into the wood using an impregnating machine that can perform various impregnation methods such as vacuum impregnation, normal pressure impregnation, or heat and pressure impregnation. Then, the other one is injected with a similar impregnating machine to inject the phenol-hexamethylenetetramine complex (
(hereinafter referred to as complex) is dispersed and fixed. The solution concentration, impregnation time, treatment pressure and treatment temperature can be changed as appropriate depending on the type, size and thickness of the wood, and the amount of resin to be impregnated. When a reaction catalyst is used, it is used after being dissolved and mixed in either a phenol solution or a hexamine solution. The concentrations of the respective solutions are adjusted so that the amounts of the phenolic monomer and hexamine fixed in the wood are 0.17 mol or more, preferably 0.25 mol or more of hexamine per 1 mol of the phenolic monomer.

[0013] The impregnation time is several tens of minutes to several tens of hours, the processing pressure is 30 mmHg to 10 Kg/cm2, and the processing temperature is room temperature to
The temperature is 70°C. The upper limit of the treatment temperature is 70 degrees Celsius, which allows the complex to be dispersed and fixed in the wood in solid form, since the dissolution temperature of the complex produced by two types of solutions is approximately 70 degrees Celsius, and the treatment solution is not contaminated with the other solution. The following temperatures are preferred.

[0014] Next, in order to make the wood on which the complex has been dispersed and fixed into resin-impregnated wood, it is preferable to heat the wood to 80 to 100°C to carry out a resin conversion reaction. In addition, the reaction pressure is normal pressure to 10
kg/cm2, and the reaction time is 1 to 5 hours, which can be changed as appropriate depending on the presence or absence of a reaction catalyst and the size and thickness of the wood. If the reaction temperature is low, the reaction time will be long and it is not practical. Furthermore, if the reaction temperature is high, the yield of the resulting resin will be poor and it will be difficult to obtain the desired impregnation rate, but it is within the scope of the present invention to carry out the reaction at a high temperature of 100°C or higher in order to shorten the production time. In that case, the desired physical properties are selected depending on the raw material cost and manufacturing cost.

[0015] Next, the resin-impregnated wood was heated to 120 to 180°C.
The curing reaction is carried out by heating at a pressure of from normal pressure to 10 kg/cm2. The reaction time is from several hours to several tens of hours, and can be changed as appropriate depending on the presence or absence of a reaction catalyst, the resin impregnation rate, and the size and thickness of the wood. It is preferable to carry out the reaction in a reduced pressure system of 30 mmHg or less for 1 to 3 hours before the end of the curing reaction in order to remove unreacted monomers. The impregnation rate of resin in wood varies depending on the intended use, but in order to improve physical properties such as dimensional stability and decay resistance, it should be adjusted to 10 to 50% (amount of impregnated resin / weight of untreated wood x 100). It is preferable that

[0016]

[Effect] In the conventional manufacturing method of modified wood using resol,
In addition to the long injection and curing times and high costs, there were also problems with physical properties such as deterioration and discoloration of the wood due to residual catalyst, but with the manufacturing method of the present invention, the viscosity of the injected solution is extremely low. Therefore, the injection time is reduced to a fraction of the conventional time. Furthermore, the curing time is shortened to a fraction of that due to the hexamine novolac reaction, making it possible to reduce manufacturing costs. Furthermore, since there is no catalyst or only a small amount is used, there is no chemical change in the structure of the wood, so deterioration of the characteristics of the wood can be minimized, and discoloration of the phenolic resin can also be prevented. In addition, since nitrogen compounds are contained in the skeleton of the cured novolak produced in the present invention, it is not only more effective in preventing discoloration of the resin, but also has high water repellency and moisture absorption. Modified wood with excellent properties can be obtained.

[0017]

[Examples] Examples of the present invention will be described below. Example 1 Phenol monomer 5k was added to an impregnation machine that can be heated under reduced pressure.
After adding g and heating to 60℃, 5cm wide x 5cm thick x
A cedar wood with a length of 50 cm was completely immersed, the pressure was reduced to 500 mmHg, and the injection treatment was performed for 30 minutes. After that, the solution in the impregnating machine was changed to 5 kg of 15% hexamine aqueous solution, the cedar wood injected with phenol monomer was introduced at room temperature, and the injection treatment was performed at normal pressure for 30 minutes to disperse and fix the complex inside the cedar wood structure. . Wash the above-mentioned injection-treated cedar wood with water, and
The phenol resin was placed in an impregnating machine adjusted to ℃ and reacted at normal pressure for 2 hours, then the temperature was raised to 150℃ and the curing reaction was carried out for 4 hours, and then the pressure was reduced to 10 mmHg and the curing reaction was continued for 1 hour. Impregnated modified wood was obtained.

Example 2 Phenol monomer 4K was added to an impregnating machine that can be heated under reduced pressure.
A mixture of 1 kg of 2% caustic soda aqueous solution and 1 kg of 2% caustic soda aqueous solution was added to completely immerse a cedar wood with a width of 5 cm, a thickness of 5 cm, and a length of 50 cm at room temperature, and the injection treatment was carried out at room temperature and pressure for 1 hour. Thereafter, the solution in the impregnating machine was changed to 5 kg of 15% hexamine aqueous solution, the cedar wood injected with the phenol monomer was introduced, and the injection treatment was carried out for 1 hour at room temperature and normal pressure to disperse and fix the complex inside the cedar wood structure. Wash the injected cedar wood with water and
After placing the phenol in an impregnation machine adjusted to 0°C and reacting at normal pressure for 1 hour, the temperature was raised to 150°C and the curing reaction was carried out for 4 hours, and then the pressure was reduced to 10 mmHg and the curing reaction was continued for 1 hour. A resin-impregnated modified wood was obtained.

Example 3 Phenol monomer 5K was added to an impregnating machine that can be heated under reduced pressure.
After adding g and heating to 60℃, 5cm wide x 5cm thick x
A cedar wood with a length of 50 cm was completely immersed, and the injection treatment was performed for 30 minutes under reduced pressure of 500 mmHg. After that, the solution in the impregnating machine was changed to a mixture of 4.9 kg of 15% hexamine aqueous solution and 100 g of 10% hydrochloric acid solution, heated to 60°C, cedar wood injected with phenol monomer was introduced, and 500 m
The injection process was performed under reduced pressure of mHg for 20 minutes to disperse and fix the complex inside the cedar wood tissue. Wash the injected cedar wood with water and place it in an impregnation machine adjusted to 80℃ for 3K.
g/cm2 After reacting for 1 hour under pressure, further 15
The temperature was raised to 0°C and the curing reaction was carried out for 2 hours, then 10
The pressure was reduced to mmHg and the curing reaction was continued for 1 hour to obtain a modified wood impregnated with a phenol resin.

Example 4 Put 5 kg of a 15% hexamine aqueous solution into an impregnating machine that can be heated under reduced pressure, completely immerse a Japanese pine tree measuring 5 cm in width x 5 cm in thickness x 50 cm in length, and heat under reduced pressure to 60°C at 100 mmHg for 30 minutes. Perform injection treatment and further increase 5Kg/cm2,
The injection process was performed for 2 hours and 30 minutes by switching to pressurized heating at 60°C. After that, the solution in the impregnating machine was changed to 5 kg of 85% phenol aqueous solution, the Karamatsu injected with the hexamine aqueous solution was added, and the injection treatment was performed again at 5 kg/cm2 and heated to 60°C for 3 hours to inject the complex inside the Karamatsu tissue. Dispersed and established. Wash the injected Karamatsu with water and give 100
After placing in an impregnating machine adjusted to ℃ and reacting for 1 hour under a pressure of 3 kg/cm2, the temperature was further raised to 150 ℃ and a curing reaction was performed for 2 hours, and then the pressure was reduced to 10 mmHg and a curing reaction was performed for 1 hour. Subsequently, modified wood impregnated with phenolic resin was obtained.

Example 5 A modified wood impregnated with a phenolic resin was obtained in the same manner as in Example 2, except that the solutions used in Example 2 were reused.

Comparative Example 1 A resol was condensed using a catalyst containing phenol and formalin in a molar ratio of 1:1.2 and 2% caustic soda. Molecular weight is 185
and the concentration of unreacted phenol was 60%, containing 10%.
% of the product was obtained. In addition to this, 10% caustic soda and 10% water
0% was added to obtain an injection resol adjusted to have a concentration of 30% and a viscosity of 40 cps/20°C. Put 5 kg of the above resol into an impregnation machine that can be heated under reduced pressure, and make a width of 5 cm.
Thoroughly soak a piece of cedar wood measuring 5cm x 5cm thick x 50cm long.
After heating to 0° C., the pressure was reduced to 30 mmHg, and injection treatment was performed for 1 hour, and then injection treatment was further performed for 5 hours under a pressure of 3 kg/cm 2 . The surface of the injection-treated cedar wood was washed with methanol, and a curing reaction was performed at 150° C. for 12 hours to obtain a modified wood impregnated with a phenol resin. The molecular weight of the resol after injection is 310 and the viscosity is 250 cps/2.
The temperature changed over time to 0°C, making it difficult to reuse. Example 1
Injection curing conditions and physical properties of Comparative Example 1 and Comparative Example 1 are shown in Table 1.

[0023]

[Table 1]

[0024]

[Effects of the Invention] According to the present invention, modified wood with improved dimensional stability, decay resistance, mechanical properties, etc. of wood can be provided in a short time and at low cost by using a low-viscosity solution that is easy to inject into wood. Therefore, the economic effects are extremely significant.

Claims (1)

[Claims] Claim 1: First, a solution of either (A) or (B) of (A) a phenolic monomer or its aqueous solution and (B) an aqueous hexamethylenetetramine solution is injected into the wood, and then (A) or (B) After the phenol/hexamethylenetetramine complex is uniformly dispersed and fixed in the wood structure by injecting the other solution of A method for producing modified wood characterized by: