JP2678345B2 - Method for producing modified wood and modified wood - Google Patents

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 flame retardancy and dimensional stability.

[0002]

2. Description of the Related Art As a conventional method for producing modified wood and modified wood, there is, for example, one disclosed in Japanese Patent Laid-Open No. 5-69414. That is, a salt or compound of a basic nitrogen compound and phosphoric acid is applied to wood and dried, and then heat-pressed to impart flame retardancy and dimensional stability to wood.

Further, as a conventional method for producing modified wood and modified wood, there is, for example, one disclosed in JP-A-62-144902. That is, after immersing the wood in the calcium chloride solution and then in the sodium phosphate solution to generate non-combustible inorganic substances in the wood, the silica sol is impregnated to give the wood flame retardancy and dimensional stability. To do.

[0004]

However, the method disclosed in Japanese Patent Laid-Open No. 5-69414 has a problem in that it is impossible to sufficiently improve the flame retardancy.

Further, in the method disclosed in Japanese Patent Laid-Open No. 62-144902, since the treatment is carried out by the two-liquid diffusion method, it takes time and effort to adjust the water content and the pH of the treated wood.
It takes time to diffuse the treatment solution, and after treatment,
It takes time to remove the remaining unreacted liquid, and
There are various problems that undesired by-products adversely affect the material.

The present invention has been made by paying attention to such conventional problems. It provides dimensional stability and improves flame retardancy, is easy to process and can be processed in a short time, It is an object of the present invention to provide a modified wood producing method and a modified wood that does not generate a product.

[0007]

In order to achieve the above object, the method for producing modified wood according to the present invention comprises a phosphoric acid treatment step of impregnating wood with a phosphoric acid compound-based flame retardant solution, A silica treatment step of impregnating wood with a silica solution, and the wood after the phosphoric acid treatment step and the silica treatment step are at a temperature of 120 to 180 ° C. or higher and 0.1 to 3
And a heating / pressurizing step of performing heating / pressurizing at a pressure of 0 kg / cm ² .

According to a second aspect of the present invention, there is provided a method for producing modified wood according to the first aspect, wherein the flame retardant solution comprises an ammonium phosphate solution, and the flame retardant solution and the silica. At least one of the solutions is characterized by containing alcohol.

The method for producing modified wood according to claim 3 of the present invention is the method for producing modified wood according to claim 1 or 2, wherein the wood after the heating and pressing step has an inorganic material having an affinity for silica. It is characterized by applying paint.

The modified wood of the present invention is characterized by containing a mixture of a phosphoric ester and a gel of silica.

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

The phosphoric acid compound-based flame retardant solution is, for example,
An aqueous solution of ammonium dihydrogen phosphate, an aqueous solution of ammonium trihydrogen phosphate, and an aqueous solution of diammonium phosphate. The flame retardant concentration in the flame retardant solution is preferably 20 to 25% by weight. The phosphoric acid compound-based flame retardant solution imparts an ignition suppressing effect to wood.

The silica solution may be an aqueous solution of colloidal silica or an alcohol solution. The silica concentration in the silica solution is preferably 20 to 30% by weight. The size of the silica particles is preferably 20 μm or less because they are impregnated into the cell wall of wood, and the particle size may be selected depending on the application. The silica solution imparts smoke eliminating effect, dimensional stability, curability, weatherability and decay resistance to wood. Although the phosphoric acid compound-based flame retardant solution does not have a sufficient smoke suppressing effect, it is possible to significantly reduce smoke during heating by impregnating it with a silica solution.

The effect of suppressing smoke generation by silica is that silica gel absorbs tar and soot having a particle size of 0.1 to 0.2 μ among smoke particles having a particle size of 0.1 to 1.0 μ generated during combustion. it is conceivable that. Further, the silica solution suppresses discoloration of wood due to the thermal oxidation of ammonia when the ammonium phosphate solution is used as the flame retardant solution.

Greoxal may be added to the phosphoric acid compound-based flame retardant solution or the silica solution in order to enhance the dimensional stability.

Regarding the phosphoric acid treatment step and the silica treatment step, the silica treatment step may be carried out after the phosphoric acid treatment step or the phosphoric acid treatment step may be carried out after the silica treatment step. It may be performed simultaneously by impregnating wood with a mixed solution of silica and silica.

The heating and pressurizing step causes a phosphoric acid esterification reaction between the flame retardant and the wood, and imparts flame retardancy to the wood. Further, it is considered that the gelation of silica proceeds due to the heating and pressurizing step, and the flame retardant is incorporated into silica gel. The hardening of the wood takes place by the production of silica gel.
Furthermore, the steam generated from the wood in the heating and pressing process
Amorphous components such as hemicellulose are decomposed and softened in wood. The softening of the wood promotes the phosphorylation reaction of the flame retardant with the wood and the formation of silica gel. Further, by pressing the softened wood, the surface of the wood is hardened.

The temperature for heat treatment in the heat and pressure step is 12
If the temperature is 0 ° C or lower, the water cannot be sufficiently drained from the wood, and it is difficult to improve the material quality. If the temperature is 180 ° C or higher, the carbonization of the wood proceeds to make it difficult to obtain industrially strong strength.
It is necessary that the temperature is 0 ° C to 180 ° C. The temperature of the heat treatment is preferably 160 to 180 ° C. in order to enhance the material improving effect by hardening the surface of the wood, forming silica gel and completely dehydrating the silica gel thus formed.

The pressure for the pressure treatment varies depending on the water content of wood, the thickness, the degree of hardening of the surface, etc., but is 0.1 kg /
The cm ² or less, since it is not possible to increase the impregnation rate of the flame retardant solution and silica solution, hardly achieving sufficient material improvement in 30kg / cm ² or more, there is a risk of destroying the timber, 0.1 It is necessary to have a pressure of 30 kg / cm ² .

The heat and pressure treatment is preferably performed after drying the wood until the water content becomes about 5 to 30%. Also,
The heating and pressurizing treatment is preferably performed by sandwiching the wood between the heating plates of the hot press in order to effectively exert the effect of steam from the wood. In this case, the heating method may be any method such as direct heating with a hot plate, steam heating, high frequency heating, or a combination of two or more of these. Depending on the thickness of the wood to be processed,
By combining these two or more heating methods, more effective modification of wood can be performed.

It is preferable that the heating and pressurizing treatment is carried out by alternately repeating pressurization and pressurization release on the wood at a predetermined heating temperature and then continuously heating and pressurizing. By repeating pressurization and release in this way, the moisture content of the wood is diffused and evaporated, the generation of the mixed gel of the flame retardant and silica on the wood surface portion can be enhanced, and the wood surface portion can be hardened. .
Further, by continuing the heating and pressurization, the hardening of the wood surface can be promoted, and the generation of the mixed gel of the flame retardant and silica inside the wood and inside the wood cells can be enhanced. The hardening of the wood improves the wear resistance of the wood.

The heating and pressurizing time includes heating temperature, pressurizing pressure,
It is set in consideration of the thickness of the wood, the degree of hardening of the surface, the degree of performance of the modified wood to be manufactured (for example, the degree of dimensional stability, rot resistance, strength performance maintenance, etc.). Minutes are preferable, and 15 to 480 minutes are particularly preferable.

When the heating and pressurizing treatment is carried out in an atmosphere containing a considerable amount of oxygen such as air, the workability of the treated wood deteriorates. Therefore, an environment containing no oxygen such as an inert gas atmosphere or a depressurized environment. It is preferable to carry out. The inert gas includes, for example, noble gases such as argon, krypton, and helium, nitrogen, ammonia, nitrous acid gas, carbon dioxide gas, and the like.
Species or two or more can be used.

When the flame retardant solution is composed of ammonium phosphate solution, it is not toxic, unlike barium chloride solution. Further, the ammonium phosphate solution has a high affinity with wood and is easily impregnated.

When an ammonium phosphate solution is impregnated as the flame retardant solution, the wood is colored black due to the thermal oxidation of ammonia in the heating and pressurizing step. However, at least one of the flame retardant solution and the silica solution should contain alcohol. Therefore, this coloring can be prevented. The alcohol is, for example, ethanol, methanol, a mixture thereof, or the like.

The inorganic coating material having an affinity for silica is, for example,
It is known as an inorganic permeation / reactivity deterioration / water absorption inhibitor, and a paint for imparting weather resistance to artificial marble or the like is particularly preferable. By applying an inorganic paint having an affinity for silica to wood, it is possible to impart water resistance and weather resistance to the wood without impairing the texture of the wood.

Embodiments 1 to 4 of the present invention will now be described with reference to the drawings.
Will be described. Each modified wood was manufactured as follows.

[0028]

Example 1 First, a cedar veneer having a thickness of 3 mm was first coated with a particle size of 1
A 20 wt% aqueous solution of 0 to 20 μ of corodyl silica was impregnated under reduced pressure, and then a 20 wt% aqueous solution of ammonium dihydrogen phosphate was impregnated under reduced pressure. Water content of wood after impregnation is 2
After drying to about 0%, the dried wood is subjected to hot pressing using a temperature condition of 160 ° C. and 0.5 to 10
Pressurization and release were repeated while changing the pressure of kg / cm ² . This heating and pressurization was performed for 5 minutes for 3 minutes, with pressurization and release as one set. Then, for wood, 16
A pressure of 10 kg / cm ² was applied for 30 minutes at a temperature of 0 ° C. Thus, the modified wood of Example 1 was manufactured.

[0029]

Example 2 The order of the method of Example 1 and the impregnation treatment was exchanged, and a similar cedar veneer was first impregnated with a 20% by weight aqueous solution of ammonium dihydrogen phosphate under reduced pressure, and then the particle size 1
A 20% by weight aqueous solution of 0 to 20 μ of colodyl silica was impregnated under reduced pressure. The impregnated wood was dried and heated and pressed under the same conditions as in Example 1. Thus,
The modified wood of Example 2 was produced.

[0030]

Example 3 The method of Example 1 and the type of silica solution were changed, and a similar cedar veneer was first impregnated with a 30 wt% methanol solution of colodyl silica having a particle size of 10 to 20 μ under reduced pressure, and then, A 20 wt% aqueous solution of ammonium dihydrogen phosphate was impregnated under reduced pressure. Example 1 for wood after impregnation
It was dried and heated and pressed under the same conditions as in the above. Thus, the modified wood of Example 3 was manufactured.

[0031]

Example 4 In order to test flame retardancy tests with different heating times, the same method as in Example 3 was used.
Modified wood was produced.

To compare the performance of the modified woods of Examples 1 to 4 with the performance of conventional modified woods, the modified woods of Comparative Examples 1 to 4 were produced as follows.

[0033]

Comparative Example 1 A cedar veneer having a thickness of 3 mm was impregnated with a 30 wt% aqueous solution of ammonium dihydrogen phosphate under reduced pressure. The impregnated wood was dried and heated and pressed under the same conditions as in Example 1. Thus, the modified wood of Comparative Example 2 was manufactured.

[0034]

[Comparative Example 2] A cedar veneer having a thickness of 3 mm was coated with a particle size of 10 to 2
A 20% by weight aqueous solution of 0 μ of colodyl silica was impregnated under reduced pressure. The impregnated wood was dried and heated and pressed under the same conditions as in Example 1. Thus, the modified wood of Comparative Example 2 was manufactured.

[0035]

[Comparative Example 3] A cedar veneer having a thickness of 3 mm was coated with a particle size of 10 to 2
A 30% by weight methanol solution of 0 μ of corrodyl silica was impregnated under reduced pressure. The impregnated wood was dried and heated and pressed under the same conditions as in Example 1. Thus, the modified wood of Comparative Example 3 was manufactured.

[0036]

[Comparative Example 4] A cedar veneer having a thickness of 3 mm was first coated with a particle size of 1
A 20 wt% aqueous solution of 0 to 20 μ of corodyl silica was impregnated under reduced pressure, and then a 20 wt% aqueous solution of ammonium dihydrogen phosphate was impregnated under reduced pressure. The impregnated wood was dried at 160 ° C. for 30 minutes using a hot air dryer. Thus, the modified wood of Comparative Example 4 was manufactured.

Next, the effect of the modified woods of Examples 1 to 4 will be described. Modified wood of Examples 1 to 4 and Comparative Example 1
To check the fire resistance of the products obtained from the modified wood of ~ 4,
Using the adhesive resorcinol, LVL (single plate laminated material) having a thickness of 13 mm was prepared from each modified wood, and the surface test and IS based on JIS1321 were prepared for this.
Ignition test based on O5927 was performed. Table 1 shows the results.
Shown in Further, graphs showing the standard temperature curve, the exhaust temperature and the smoke emission coefficient of the results are shown in FIGS.

[0038]

[Table 1]

In Table 1, Tθ indicates a temperature time exceeding the standard temperature curve, and Tdθ indicates a temperature time area exceeding the standard temperature curve. It can be seen from Table 1 and FIGS. 1 to 8 that the modified woods of Examples 1 to 4 have improved flame retardancy as compared with the modified woods of Comparative Examples 1 to 4. According to the first embodiment, JIS
The flame retardancy was improved so that the flame retardancy class 1 standard of the A1321 combustion test was satisfied and the flame retardancy class 2 standards of Examples 2 and 3 were satisfied.

With respect to the modified woods of Examples 1 and 3, the modified wood of Comparative Example 1 and the untreated wood, an inorganic coating material having an affinity for silica (trade name: Hydrotherm, manufactured and sold by Nippon Chemix Corporation) Co., Ltd.) and dried wood was boiled at 100 ° C. for 8 hours. A water resistance test was performed on these treated woods.

The water resistance test was conducted under stricter test conditions for the JAS flame-retardant plywood type 1 immersion peel test. That is, after immersing the test piece in boiling water for 4 hours, 105 ± 3
It was dried at 0 ° C. for 20 hours, further immersed in boiling water for 4 hours, and then dried at 60 ± 3 ° C. for 48 hours. Thereby, the water absorption rate, the dimensional change rate, and the leaching rate were obtained. The water absorption was determined by the total dry weight method. The dimensional change rate was obtained from the dimensional change in the thickness direction of the test piece. The leaching rate was determined by dividing the total dry weight before the test by the total dry weight after the test by the total dry weight before the test and multiplying the value by 100. Table 2 shows the results.

[0042]

[Table 2]

It can be seen from Table 2 that the modified woods of Examples 1 and 3 have improved water resistance as compared with the modified wood of Comparative Example 1. When the inorganic coating material having an affinity for silica was applied, the water resistance of the modified wood of Comparative Example 1 was hardly changed, whereas the modified wood of Examples 1 and 3 was applied. It can be seen that the water resistance of the coated product is further improved as compared with that of the uncoated product.

The modified wood of Example 1, the modified wood of Comparative Example 2 and the untreated wood were subjected to the abrasion resistance test of JAS special plywood. Table 3 shows the results.

[0045]

[Table 3]

It can be seen from Table 3 that the modified wood of Example 1 has improved abrasion resistance as compared with the modified wood of Comparative Example 2 and the untreated wood.

The wood colors of the modified woods of Examples 1 and 3, the modified wood of Comparative Example 1 and the untreated wood were measured with a colorimeter. Further, with respect to these woods, the dimension when completely dried and the dimension after boiling treatment in hot water of 100 ° C. for 8 hours were measured, and the dimensional change rate was calculated in order to check the dimensional stability. Table 4 shows the results.

[0048]

[Table 4]

In Table 4, "L ☆" indicates the lightness index, and "a"
"☆" indicates the chromaticness index in the red direction, and "b ☆"
Indicates the chromaticness index in the yellow direction. It can be seen from Table 4 that the modified woods of Examples 1 and 3 have better dimensional stability and smaller color difference than the modified wood of Comparative Example 1. The modified wood of Example 3 impregnated with the methanol solution has particularly good dimensional stability and a small color difference.

[0050]

EFFECT OF THE INVENTION According to the method for producing modified wood and the modified wood according to the present invention, dimensional stability is imparted and flame retardancy is imparted by the synergistic effect of phosphoric acid esterification of wood and gelation of silica. Improve sex. Further, according to the method for producing modified wood according to the present invention, the water content and pH of the wood to be treated are
The process is easy and can be completed in a short time, for example, the process solution can be diffused in a short time, without the need for adjusting. Furthermore, according to the method for producing modified wood according to the present invention, it is not necessary to remove the unreacted liquid after the treatment, and since unintended byproducts are not generated, deterioration of the material due to this is prevented. It can be avoided.

Particularly, in the method for producing modified wood according to the second aspect of the present invention, since the ammonium phosphate solution is used as the flame retardant solution, when a dangerous substance or deleterious substance such as barium chloride solution is used. In comparison, the occupational hygiene environment can be made safe, and the use of alcohol can suppress the coloring of wood.

In particular, in the method for producing modified wood according to claim 3 of the present invention, water resistance and weather resistance can be easily imparted to wood by applying an inorganic coating material having an affinity for silica. The possibility of using wood outdoors as an exterior member can be expanded.

The modified wood manufactured by the method for manufacturing modified wood according to the present invention is, for example, woodworking material, table or other furniture material, interior material for automobiles and buildings, window frame, structural LVL, It can be used as a laminated wood exterior, wooden door, decorative wood for system kitchen, etc.

[Brief description of the drawings]

FIG. 1 is a graph showing a standard temperature curve, an exhaust temperature, and a smoke emission coefficient of modified wood obtained by a method for manufacturing modified wood according to Example 1 of the present invention.

FIG. 2 is a graph showing a standard temperature curve, an exhaust temperature and a smoke emission coefficient of modified wood produced by the method for manufacturing modified wood of Example 2 of the present invention.

FIG. 3 is a graph showing a standard temperature curve, an exhaust temperature, and a smoke emission coefficient of modified wood produced by the method for manufacturing modified wood of Example 3 of the present invention.

FIG. 4 is a graph showing a standard temperature curve, an exhaust temperature, and a smoke emission coefficient of modified wood obtained by the method for manufacturing modified wood of Example 4 of the present invention.

FIG. 5 is a graph showing a standard temperature curve, an exhaust temperature, and a smoke emission coefficient of a modified wood produced by a method for producing a modified wood of Comparative Example 1 of the related art.

FIG. 6 is a graph showing a standard temperature curve, an exhaust temperature, and a smoke emission coefficient of modified wood obtained by a conventional modified wood manufacturing method of Comparative Example 2.

FIG. 7 is a graph showing a standard temperature curve, an exhaust temperature, and a smoke emission coefficient of modified wood obtained by a conventional modified wood manufacturing method of Comparative Example 3.

FIG. 8 is a graph showing a standard temperature curve, an exhaust temperature, and a smoke emission coefficient of modified wood produced by a method for manufacturing modified wood of Comparative Example 4 of the related art.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor, Kowei 336-1 Kamidai, Kanayama-cho, Mogami-gun, Yamagata Yamagata Wood Tech Co., Ltd. (72) Inventor Hirozo Mitsuhashi 3-11 Teraoka, Izumi-ku, Sendai, Miyagi -21

Claims (4)

(57) [Claims] 1. A phosphoric acid treatment step of impregnating wood with a phosphoric acid compound-based flame retardant solution, a silica treatment step of impregnating wood with a silica solution, and a phosphoric acid treatment step and wood after the silica treatment step. Temperature of 120-180 ° C and 0.1-30 kg / c
a heating and pressurizing step of heating and pressurizing at a pressure of m ² . 2. The method for producing modified wood according to claim 1, wherein the flame retardant solution comprises an ammonium phosphate solution, and at least one of the flame retardant solution and the silica solution contains alcohol. 3. The inorganic coating material having an affinity for silica is applied to the wood after the heating and pressing step.
Or the method for producing modified wood according to 2. 4. Modified wood comprising a mixture of a phosphoric acid esterified product and a gelled product of silica.