JPH07178706A - Manufacture of modified wood - Google Patents

Abstract

PURPOSE:To improve properties of wood which is easy to warp, rot and burn, to prepare easily an improved wood with excellent dimensional stability, durability and flame retardancy and to treat even a thick material and a material with a complicated shape by incorporating integrally a flame-retardant into the wood and giving a high temp. heat treatment to it. CONSTITUTION:A method for manufacturing an improved wood consists of a composing process wherein a flame-retardant is incorporated into the tissue of a wood and a heating process wherein the wood is heat-treated at a temp. of 100-250 deg.C under an inert gas atmosphere.

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 having dimensional stability, decay resistance and flame retardancy.

[0002]

2. Description of the Related Art As a conventional method for producing modified wood, there is, for example, one disclosed in Japanese Patent Laid-Open No. 60735/1990.
That is, wood is impregnated individually with two or more kinds of inorganic aqueous solutions that produce an inorganic flame retardant when mixed, thereby imparting flame retardancy to the wood.

Further, as a conventional method for producing modified wood,
For example, there is one disclosed in Japanese Patent Publication No. 58-18205. That is, the wood is subjected to high temperature and high pressure treatment in a non-flammable gas atmosphere to impart dimensional stability to the wood.

Further, as another conventional method for producing modified wood, there is, for example, one disclosed in Japanese Patent Laid-Open No. 5-69414. That is, a compound containing a salt of a basic nitrogen compound and phosphoric acid as a main component is applied to the surface of wood and dried, and then heat-pressed to impart dimensional stability and flame retardancy to the wood.

[0005]

However, although the method disclosed in Japanese Patent Application Laid-Open No. 2-60735 can impart flame retardancy to wood, it is necessary to sufficiently improve dimensional stability and decay resistance. There was a problem that I could not do it.

The method disclosed in Japanese Patent Publication No. 58-18205 has a problem that dimensional stability can be imparted to wood, but flame retardancy and decay resistance cannot be sufficiently improved. there were.

Further, the method disclosed in Japanese Patent Laid-Open No. 5-69414 has problems that it requires expensive equipment for hot pressing and that it is difficult to process wood having a complicated shape. .

The present invention has been made by paying attention to the above-mentioned conventional problems, and the wood is liable to be eclipsed and rot easily.
It is an object of the present invention to provide a method for producing a modified wood, which is capable of easily producing a modified wood having dimensional stability, decay resistance and flame retardancy by improving the property of being easily burned.

[0009]

In order to achieve the above object, the method for producing modified wood according to the present invention comprises a composite step of adding a flame retardant in the structure of wood and 100 to 25 wood.
And a heating step of performing heat treatment at a temperature of 0 ° C.

The wood used as the raw material for the modified wood may be cedar, beech, zelkova, zelkova, dogwood, or any other tree, and may be broad-leaved or coniferous.

The flame retardant may be an inorganic flame retardant or an organic flame retardant. The organic flame retardant is, for example, an organic phosphorus / nitrogen-based polymer compound. The inorganic flame retardant is
For example, phosphate, hydrogen phosphate, borate, carbonate,
One or two of sulfates, hydrogensulfates, silicates, nitrates, fluorides, bromides, hydroxides and other insoluble inorganic substances
Made of more than one seed.

More specifically, the inorganic flame retardant is, for example, an alkaline earth metal such as Ba, Mg, Ca or Sr, Z.
n, Al, other transition elements such as Mn and Cd, Si and P
Carbon group element such as b, one or more cations such as alkali metal such as Na and K, and BO ₃ , PO ₄ , and C
O ₃ , SO ₄ , OH, others, F, Cl, Br, O, N
One or two anions such as O ₃ , SiO ₄ , and SiO ₃
Composed of seeds and more.

The complexing step may comprise the step of impregnating the wood with the flame retardant solution. The flame retardant solution is composed of, for example, one or a combination of two or more of phosphorus compounds, phosphorus nitrogen compounds such as ammonium polyphosphate, phosphorus halogen compounds, halogen compounds, boron compounds, antimony compounds, silica compounds and other compounds. It is an aqueous solution.

The complexing step may also include the step of impregnating the wood with two or more flame-retardant solutions that produce an insoluble flame retardant in the tissue of the wood by the reaction. in this case,
As the two or more flame-retardant solutions, a flame-retardant aqueous solution that produces an insoluble inorganic cation and a flame-retardant aqueous solution that produces anions thereof can be used. The flame-retardant aqueous solution which produces a cation or an anion can use 1 type (s) or 2 or more types, respectively. Due to the reaction between the cation and the anion, one kind or two or more kinds of insoluble inorganic substances are formed in the wood, and the flame retardancy of the wood is exhibited.

More specifically, as an aqueous solution for producing a cation of an inorganic flame retardant, for example, BaCl ₂ , Ba
Cl ₂ · 2H ₂ O, BaBr ₂ , Ba (NO ₃ ) _2, Mg
Cl ₂ , MgBr ₂ , MgSO ₄ · H ₂ O, Mg (NO
_{3) 2 · 6H 2 O,} CaCl 2, CaBr 2, Ca (N
_{O 3) 2, AlCl 3,} AlBr 3, Al 2 (SO 4) 3,
_{Al (NO 3) 3 · 9H} 2 O, may be used an aqueous solution consisting of one or more combinations of ZnCl ₂ or the like, as an aqueous solution to produce an anion of the inorganic flame retardant, Na ₂ CO _3, ( NH ₄ ) ₂ CO ₃ , H ₂ SO ₄ , N
a ₂ SO ₄ , (NH ₄ ) ₂ SO ₄ , H ₃ PO ₄ , Na ₂ H
PO ₄ , (NH ₄ ) ₂ HPO ₄ , H ₃ BO ₃ , NaB
It is possible to use an aqueous solution of one kind or a combination of two or more kinds such as O ₂ and NH ₄ BO ₂ .

It is preferable that the complexing step comprises a step of degassing the wood under reduced pressure and then impregnating the wood with the flame retardant solution under pressure.

Further, the compounding step may comprise a step of depressurizing one end of the wood mouth surface and pressurizing the periphery of the wood to impregnate the wood with the flame retardant solution. This method is a so-called wood-mouth impregnation method. The wood mouth surface is a surface obtained by cutting wood in a direction transverse to the trunk axis direction.

In addition, the method of impregnating wood with the flame retardant solution may be a method of applying the flame retardant solution to wood depending on the application.

The temperature at which wood is heat-treated in the heating step is 1
If the temperature is 00 ° C or lower, it is difficult to improve the material simply by drying the wood, and if the temperature is 250 ° C or higher, the carbonization of the wood proceeds and it is difficult to obtain the strength that can be industrially endured.
It requires a temperature of 250 ° C.

The heating time is set in consideration of the heating temperature and the plate thickness. The order of the complexing step and the heating step may be either the complexing step followed by the heating step or the heating step followed by the complexing step. However,
If the heating step is performed after the complexing step, it is possible to simultaneously dry the wood that has been wet by the impregnation treatment in the complexing step by the heat treatment.

In particular, it is preferable that the heating step comprises a step of heat-treating the wood in an inert gas atmosphere at a temperature of 160 to 200 ° C. for 5 to 30 hours.

If the heat treatment is carried out in an atmosphere containing a considerable amount of oxygen such as air, the workability of the treated wood deteriorates. Therefore, the heat treatment is carried out in an oxygen-free environment such as an inert gas atmosphere or a reduced pressure environment. It is preferable.

As the inert gas, for example, rare gas such as argon, krypton or helium, nitrogen, ammonia, nitrous acid gas, carbon dioxide gas or the like may be used alone or in combination of two or more kinds.

[0024]

In the method for producing modified wood according to the present invention, flame retardancy is imparted to wood by including a flame retardant in the structure of the wood in the compounding step. By heating the wood in the heating step, the dimensional stability of the wood is greatly improved. On the other hand, the synergistic action of the compounding step and the heating step also greatly improves the decay resistance of the wood. From these facts, the modified wood having dimensional stability, decay resistance and flame retardancy can be realized by using the combination step and the heating step together.

In the method for producing modified wood according to the fifth or sixth aspect of the present invention, wood can be efficiently impregnated with the flame retardant solution, and the wood and the flame retardant can be sufficiently compounded.

In the method for producing modified wood according to the present invention of claim 7, the wood is treated under heating conditions more suitable for imparting dimensional stability and decay resistance.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Modified wood was produced as follows. (1) First, the cross section divided into sapwood and heartwood is 30 mm x 3
A cedar wood piece having a size of 0 mm and a thickness of 5 mm and two kinds of inorganic aqueous solutions were prepared. 5 for two types of inorganic aqueous solutions
%, 10%, 20%, and 30% by weight of barium chloride aqueous solutions having different concentrations and ammonium hydrogenphosphate aqueous solutions having the respective concentrations were prepared.

The piece of wood was degassed by a vacuum pump under reduced pressure, and then a 5% aqueous barium chloride solution was pressed at a pressure of 2.0 MPa for 4 hours to impregnate the piece of wood. Then 5%
An aqueous solution of ammonium hydrogen phosphate having a concentration was pressed at a pressure of 2.0 MPa for 4 hours to impregnate the wood piece. By the impregnation treatment of this pressure reduction / pressurization method, barium chloride and ammonium hydrogen phosphate were reacted in the tissue of the wood piece to produce insoluble inorganic flame retardant barium hydrogen phosphate.

Similarly, for each piece of wood, 10%, 20
% And 30% by weight of barium chloride aqueous solution and corresponding corresponding concentrations of ammonium hydrogen phosphate aqueous solution were sequentially pressure-impregnated.

After the composite step, the wood pieces are subjected to 160 ° C., 170 ° C., 180 ° C. for each wood piece under a nitrogen gas atmosphere.
Heat treatment was carried out at each temperature of ° C, 190 ° C, and 200 ° C for 8 hours. In this way, modified wood having different impregnation rates and heating temperatures was produced for each of the sapwood and the heartwood.

Modified wood was also produced by the other method described below. (2) First, the cross section is 120 mm x 120 mm and the length is 6
A cedar square lumber having a size of 00 mm and two kinds of inorganic aqueous solutions were prepared. As the two kinds of inorganic aqueous solutions, a barium chloride aqueous solution having a concentration of 30% by weight and an ammonium hydrogenphosphate aqueous solution having a concentration of 30% by weight were prepared.

While depressurizing the wood surface of one end of the timber to a pressure of 1.3 KPa, the periphery of the timber is pressurized at a pressure of 0.5 MPa, and a barium chloride aqueous solution having a concentration of 30% by weight is added to 6
The square wood was impregnated by pressure injection for a period of time. Next, the square bar was similarly impregnated with an aqueous solution of ammonium hydrogen phosphate having a concentration of 30% by weight. By the impregnation treatment of the wood mouth impregnation method, insoluble inorganic barium hydrogen phosphate was produced in the tissue of the timber.

The timber after the composite process was cut into pieces of wood having a cross section of 30 mm × 30 mm and a thickness of 5 mm. These pieces of wood are treated at 160 ° C., 170 ° C., 180 ° C., 190 ° C.
Heat treatment was performed at each temperature of 0 ° C. for 8 hours. Thus, modified woods having different heating temperatures were manufactured.

Next, the action and effect of the manufactured modified wood will be described. The impregnation rate of the wood piece after the complexing step was determined as follows using the wood piece manufactured according to (1) above. After the impregnation, a piece of wood measuring 30 mm × 30 mm × 5 mm is heated at 240 ° C. for 80 minutes,
After carbonization, heat at 600 ° C. for 40 minutes, then 8
Ignition heating was performed at 50 ° C. for 90 minutes. After cooling each piece of wood, the weight was measured, and the piece was heated again at 850 ° C. for 60 minutes, and heating at 850 ° C. was repeated until the change in weight twice consecutively became 2 mg or less.

With respect to the ash content having a weight change of 2 mg or less, the weight% was determined based on the absolute dry weight of each piece of wood, and the value was used to determine the impregnation rate from the following formula.

G = [(A−A ₀ ) / (1−A)] × 100

However, G is the impregnation rate [%], A ₀ is the ash content [%] of the unimpregnated material, and A is the ash content [%] of the impregnated material. The results are shown in Table 1.

[0038]

[Table 1]

From Table 1, it can be seen that the impregnation rate increases in proportion to the concentration of the flame retardant solution, and when the sapwood and the core material are compared, the sapwood exhibits a higher impregnation rate.

Next, a dimensional stability test was conducted on each modified wood produced. In the dimensional stability test, test pieces were prepared in accordance with "Wood Shrinkage Rate Measuring Method" (JIS Z 2103), and the sapwood and the core material produced by the above (1) differed in impregnation rate and heating temperature. Modified wood, wood that was impregnated but not heat-treated, and unheated and unimpregnated wood were used as samples.

First, these samples were placed in a thermo-hygrostat and kept at 40 ° C. and 45% RH for 8 days, and then at 40 ° C. and 90% R.
Hold at H for 6 days. The area expansion coefficient is calculated from the dimension in the tangential direction (grain direction) and the dimension in the radial direction (grain direction) in each environment, and the ASE (from the following equation based on the area expansion coefficient of unheated and unimpregnated wood) Anti-contraction ability) was determined.

ASE [%] = [(D ₀ −D) / D ₀ ] × 100

However, D ₀ is the area expansion coefficient of unheated and unimpregnated wood, and D is the area expansion coefficient of modified wood. The results of this dimensional stability test are shown in FIG. 1 for a sample manufactured from sapwood.
2 shows a sample manufactured from the core material.

From FIGS. 1 and 2, when the ASE value of the modified wood is compared with the ASE value of unheated wood (shown at a heating temperature of 40 ° C.), both sapwood and heartwood of the modified wood are ASE.
It can be seen that the value is greatly improved. Further, the ASE value of the modified wood is different from that of the unimpregnated wood, and the ASE value of the modified wood is 180 ° C. for both the sapwood and the heartwood.
It can be seen that there is a peak of the value in the vicinity and the optimum heating temperature range is near the temperature.

Next, a decay resistance test was conducted on each modified wood produced. The decay resistance test was performed in accordance with "Wood decay test method" (JIS Z 2119 (1969)). As the sample, modified wood (impregnation rate: 27%) produced by using the wood mouth impregnation method in the compounding step was used. As test strains, Pleurotus cornucopiae and Pleurotus cornucopiae were used.

First, the sample was placed on the culture medium in which the test strain was pre-cultured and cultured at a temperature of 25 ° C. for 60 days. The weight reduction rate was calculated from the weight change of the sample before and after the culture. The larger the value of the weight reduction rate, the more likely it is to perish. The results of this decay resistance test are shown in FIG.

From FIG. 3, comparing the weight loss rate of the modified wood with the weight loss rate of the unheated / non-impregnated wood, the modified wood is higher than the unheated / unimpregnated wood at a temperature of 180 ° C. or higher. The weight reduction rate has been greatly reduced to less than half, and a remarkable effect of decay resistance is recognized. Also, comparing the weight loss rate of the modified wood with that of the unimpregnated wood, the weight loss rate of the modified wood is greatly reduced in the temperature range of 160 ° C to 200 ° C as compared with the unimpregnated wood. Therefore, a remarkable effect of decay resistance is recognized. From these, it can be seen that the modified wood has improved decay resistance due to the synergistic action of the complexing step and the heating step.

In particular, in the unimpregnated wood, in the temperature range of 170 ° C. or lower or 190 ° C. or higher, the weight reduction rate is larger than that of the unheated / non-impregnated wood, and the weight reduction rate is improved. Temperature is limited to 180 ° C. Therefore, it is considered necessary to strictly control the temperature of unimpregnated wood in order to improve the decay resistance. On the other hand, the modified wood has an advantage that the temperature management is not required to be strict because the weight reduction rate is greatly improved by heat treatment at a temperature of 180 ° C. or higher.

Since the modified wood contains barium hydrogen phosphate which is an inorganic flame retardant in the wood structure, the flame retardancy of barium hydrogen phosphate is imparted.

[0050]

EFFECTS OF THE INVENTION According to the method for producing modified wood according to the present invention, it is possible to treat a material having a large plate thickness or a material having a complicated shape, and all of dimensional stability, decay resistance and flame retardancy are achieved. It is possible to produce a modified wood with. The manufactured modified wood can be used as a woodworking material, a furniture material, an automobile interior material, a building material, or the like.

[Brief description of drawings]

FIG. 1 is a graph showing the dimensional stability test results of modified wood of one example of the present invention when sapwood is used as a material.

FIG. 2 is a graph showing the dimensional stability test results of modified wood of one example of the present invention when a core material is used as a material.

FIG. 3 is a graph showing the results of the decay resistance test of the modified wood of one example of the present invention.

Claims (7)

[Claims] 1. A method for producing modified wood, comprising: a composite step of including a flame retardant in the structure of the wood; and a heating step of heat-treating the wood at a temperature of 100 to 250 ° C. 2. The method for producing modified wood according to claim 1, wherein the flame retardant is an inorganic flame retardant. 3. The method for producing modified wood according to claim 1, wherein the complexing step comprises a step of impregnating the wood with the flame retardant solution. 4. The complexing step comprises the step of impregnating the wood with two or more flame-retardant solutions which produce an insoluble flame retardant in the tissue of the wood upon reaction. Method for producing modified wood of. 5. The compounding step comprises a step of deaeration or depressurization of wood to pressurize it to impregnate the wood with the flame retardant solution.
A method for producing the modified wood described. 6. The compounding step comprises the step of decompressing one end of the wood mouth surface and pressurizing the periphery of the wood to impregnate the wood with the flame retardant solution. 2. The method for producing modified wood according to 2 or 3. 7. The heating step comprises the step of heat-treating wood in an inert gas atmosphere at a temperature of 160 to 200 ° C. for 5 to 30 hours.
The method for producing modified wood according to 3, 4, 5 or 6.