JPH10272610A - Wood having capability for sterilizing wood-rotting fungus and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain breed of wood rotting fungi penetrated into a place in which water content coexists by a method wherein wood is impregnated with silver-ion substituted zeolite of a specific particle size or under. SOLUTION: Zeolite of 500 μm or under particle size is used. For example, A-type zeolite of 2 μm average particle size is dipped in diluted solution of silver nitrate, replacement treatment to a silver ion is executed, and silver ion replaced A-type zeolite is adjusted. Besides, wood is charged into a hermetically sealed container. An inside of the container is evacuated with a vacuum pump, disspersion liquid in which the silver ion exchanged A-type zeolite is mixed is charged therein, and the wood is dipped in the aqueous solution. Then, the container is kept pressurized. The wood is taken out, allowed to stand in the shade, and dried naturally. When water penetrates the wood, the silver ion supported with the zeolite is eluted by being induced with the water content, wood deteriorating fungi are annihilated with high bacteriocidal capacity of a hydroxyl radical generated thereby, and damage of termite is eliminated by restraining breeding of the rotting fungi.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to wood having the ability to kill wood rot fungi and a method for producing the wood. More specifically, the present invention relates to a method for impregnating a zeolite carrying silver ions into a wood tissue to obtain the wood. The present invention relates to a means for dissolving silver decay fungi by dissolving silver ions when water has entered the water.

[0002]

Background of the Invention Wood decay and associated harm of termites are considered to be a major problem in wooden buildings and civil engineering, and this is thought to be due to the following mechanism. That is, in the wood, dew water, rainwater, water used, water infiltrated by soil water, etc., in addition to the water, when oxygen, temperature, nutritional conditions are aligned, spores of wood rot fungi germinate, or The fungi of the wood rot fungi grow from plant remains and soil, and absorb the nutrients of the wood during the growth of the fungi, causing them to rot. The wood-rotting fungi broadly refers to those belonging to the fungi shown in FIG. 11 and having the ability to rot wood, but narrowly refers to those belonging to basidiomycetes. The rot fungi include brown rot fungi, white rot fungi, and soft rot fungi. The inside of the wood is devastated,
Damage has been caused. Further, although the white rot fungus has no attracting action, the wood decomposed by the white rot fungus becomes very easy to eat for termites, and similarly causes severe damage. This phenomenon tends to produce dew condensation inside the building as the building is recently insulated and hermetically sealed, and the damage tends to increase greatly.

[0003]

2. Description of the Related Art In contrast, conventional means for controlling termites are:
It is common to apply a preservative. Specifically, (a) a method of applying an organophosphorus insecticide, a carbamate insecticide, or a pyrethroid insecticide that kills by killing insects, (b) chromium, So-called C injecting copper and arsenic compound preservatives under pressure
A method of performing a CA process and the like are performed.

[0004] However, in the means (a), since the organic pesticide is volatile, harmful organic pesticide components are filled in the room after construction, causing autonomic imbalance such as headache and dizziness. There is fear. In the means (b), chromium, copper,
The base soil is contaminated because it contains heavy metal compounds such as arsenic.When dismantling and recycling homes, harmful substances such as arsenic, hexavalent chromium, and copper, etc. are dissolved from wood or contaminated. It is pointed out that there is a risk that the soil near the base may spread and spread pollution.

On the other hand, the existence of antibacterial ceramics carrying silver ions is known. These antibacterial ceramics exhibit antibacterial properties mainly against bacteria and molds, and therefore, wood decay fungi. Those that propagate with mycelia and spores are less effective and have not developed to the point where they can be effectively used as termite countermeasures. The antibacterial mechanism is also recognized by the Japanese Society for Antifungal and Fungicidal Causes due to its reaction with the -SH group of bacteria and fungi, but its reliable antibacterial function has not been certified.

[0006] As an antibacterial treatment method for wood products,
A method for antibacterial treatment of wood products (Japanese Patent Application Laid-Open No. 7-205115) has been proposed. The outline of the method is to finely pulverize glass containing silver oxide to form fine glass particles, and disperse the glass particles in water. By holding the wooden particle and the glass particle-dispersed water, such as a food crate, in the pressure-resistant treatment container, and depressurizing and pressurizing the pressure-resistant treatment container, the glass particle-dispersed water penetrates into the tissue of the wooden product. It becomes. However, such silver oxide is in the form of Ag ₂ O or AgO, and has a low oxidizing power and is effective in suppressing the growth of bacteria and molds. It is not applicable.

[0007]

DISCLOSURE OF THE INVENTION The present invention has been made based on the above-mentioned circumstances, and has focused on the bactericidal properties of a zeolite carrying silver ions. Investigating the mechanism of the bactericidal action, it was found that wood rot fungi caused by the invasion of wood rot fungi in a place where water coexists were found to be extremely effective in suppressing the growth of the wood rot fungi, and completed the present invention. is there.

[0008]

First, the preparation of a zeolite having a particle size of 500 microns or less in which silver ions have been substituted is started. Zeolite is an SiO ₄ tetrahedron whose structure has O at the four vertices of a regular triangular pyramid and Si ⁴⁺ at the center, and Si ⁴⁺
Instead of Al ³⁺ , a SiO ₄ tetrahedron is substituted with a tetrahedral oxygen atom at the top, a skeleton is formed by a three-dimensional network structure, and at the same time gaps (pores) are included in the network structure. Have. Since aluminum is trivalent, AlO
_The tetrahedron shows minus one valence, and zeolite is negatively charged by the number of aluminum. To neutralize this, zeolite coordinates a positively charged cation in pores near the aluminum skeleton, and polar molecules of water are coordinated to the cation. Therefore, when the ratio of Si to Al is 1: 1, the ratio of the negative charge is the highest (Si-
Although the bond between O-Si and Si-O-Al is established, Al-
Loewenstei says OAl bond is not established
The substitution rate of silver ions becomes highest due to the n rule). For A-type zeolite is applicable to it, the composition per unit lattice framework _{(SiO 2) 12 (AlO 2} ) - 12 represented the pore ^{_{Na + 12 · (H 2 O}} ) 27.

The cations (Na ^{+ in the} above formula) and water in the pores are easy to move, and are easily replaced by other cations depending on the conditions of the solution containing the zeolite, which is cation exchange. Therefore, the zeolite is immersed in a silver ion solution such as a silver nitrate solution, and is substituted or impregnated with an alkali ion such as Na ⁺ ion contained during synthesis or in the presence or absence of the zeolite. Ag ⁺
A zeolite supporting ions is prepared.

At this time, the size of the zeolite is desirably 500 μm or less for natural zeolite and 8 μm or less for synthetic zeolite. This is because wood pipes, such as hinoki, sawara, hiba, beech, and mizunara, which are often used for building materials, earth and timber, have a diameter of several hundred microns to several tens of microns, and have a zeolite wood structure described later. Considering impregnation into
This is because the particle diameter becomes easy to penetrate into the conduit. As a result, the size of zeolite is suitable for a particle size of 500 microns or less.However, in the case of natural zeolite, it takes time to pulverize the lumps, so it is better to use particles having a relatively large diameter. On the contrary, it is more economical to use synthetic zeolite from small particles because it is granulated from small fine particles.Select the particle size in consideration of the diameter of the conduit and this economy. Shall be.

Next, the zeolite supporting the silver ions is permeated into the wood. This is for killing as much as possible of wood rot fungi that invade not only on the surface but also inside due to the penetration of water into the wood. The method of infiltration does not matter, but for example,
The wood is once depressurized to remove bubbles, vaporized components, etc. inside the conduit, and then immersed in the above zeolite suspension, and if necessary, pressure or ultrasonic vibration is applied, or rubbed, through the conduit. Aim to penetrate inside the organization.

Next, it was examined how Ag + ions carried in the zeolite elute into the water when the water enters. This is because the ion exchange phenomenon is a reversible process, and when silver ion-exchanged zeolite is put into water, reverse ion exchange, that is, elution of silver ions, cannot be avoided. At this time, the amount of silver ions eluted differs depending on the type of aqueous solution in contact with the zeolite. Therefore, silver ion exchanged zeolite A was tested for elution of silver ions, which is the primary basis of the bactericidal action. Test method: 60 degrees of Pseudomonas oryzae in a 27 ° C constant temperature bath
200 ml of distilled water in an incubator grown for logarithmic growth for a period of time
3 WT% silver ion exchange type A zeolite 300mg
(1.5 g / L) was added. After a part of the solution was sampled and passed through a membrane filter to separate mycelia of Pleurotus versicolor, the amount of Ag ⁺ ion in the solution was measured by a flame atomic absorption spectrometer. The results were as shown by the circles in FIG. As a result, after the addition, about 5 to 10
After minutes, Ag ⁺ ions eluted as much as 7 μM (M = mol / L), and eluted immediately from the zeolite into water after intrusion of water. As a result, it was found that Ag ⁺ ions could be activated using the invading water.

Next, the mechanism of the germicidal action of Ag ⁺ ions eluted from the zeolite in an aqueous solution was examined. Test method: 60 degrees of Pseudomonas oryzae in a 27 ° C constant temperature bath
200 ml of distilled water in an incubator grown for logarithmic growth for a period of time
3 WT% silver ion exchange type A zeolite 300mg
(1.5 g / L), 5 minutes, 20 minutes, 35 minutes,
At 0 minute and at each time, the sampled solution was passed through a membrane filter to separate mycelia, and then DM solution was added to the solution.
PO (5,5-dimethyl-1-purroli
ne-1-oxide) was added, and electron resonance (ESR) was measured by a spin trap method in which radicals in the solution were made into spin adducts. The results of quantification of the ESR peak by H-tempor were as shown in FIGS. 2 and 3 (a) to (d). As a result, the peak of the radical was observed, and the expression of the .OH radical was confirmed.
Minutes, 20 minutes, 35 minutes, 50 minutes, etc., it was confirmed that the expression was continuous at each time. Although the lifetime of the .OH radical is very short, 10 ⁻⁹ , it can be seen from the measurement at each measurement time that it continuously occurs.

Further, in order to examine the correlation between the amount of Ag ⁺ ion eluted and the amount of .OH radicals, Ag was added when 300 mg of 3 WT% silver ion-exchanged A-type zeolite was added to 200 ml of distilled water of a Japanese quail mushroom incubator. ^{The change of +} ion elution amount and .OH radical amount was determined. The result is shown in FIG.
As shown, a proportional relationship was observed at a certain rate between the amount of Ag ⁺ ion eluted and the amount of .OH radical.

Next, it was examined how much the wood rot fungus was killed by the elution of the Ag ⁺ ion and the sterilization mechanism. Test method: 300 mg (1.5 g of 3 WT% silver ion-exchanged zeolite A in 1.5 ml of distilled water in 200 ml of incubator grown on a logarithmic culture by cultivating the Japanese quail mushroom strain and the Kawatake mushroom strain in a 27 ° C constant temperature bath for 60 hours and 48 hours, respectively / L) was added thereto, and 1 ml was taken from the incubator over time while stirring in a constant temperature bath at 27 ° C., an agar medium was poured, and after culturing for 72 hours, colonies were counted. The results were as shown in FIGS. As a result, the survival rate was 75 m
g added exponentially decreases up to 30 minutes, decreases to about 80% after 4 hours, and
g, 300 mg, and 450 mg, exponentially decrease until 30 minutes, and 90% at 300 mg after 1 hour.
Decreased to below. In the case of Kawatake, the survival rate is 75m.
In the case of the addition of g, the exponential series decreases until 30 minutes, and decreases to about 90% or less after 2 hours. Below, 150
Even in the cases of 300 mg, 300 mg and 450 mg, they decreased exponentially until 30 minutes, and decreased to 95% or less after 2 hours. As a result, it was confirmed that a certain proportional relationship was recognized between the silver ion exchange type A zeolite and the reduction of wood rot fungi. Incidentally, the concentration of the silver ion-exchanged A-type zeolite, when converted to the concentration in wood, is equivalent to that present in 1.5 cm of wood in 10 cm ³ of wood. Bactericidal properties in wood can be exhibited by the silver ion exchange type A zeolite.

Next, changes in the amount of Ag ⁺ ion eluted and the survival rate of wood rot fungi were determined, as shown in FIG.
FIG. 8 shows changes in the amount of .OH radicals and the survival rate of wood-rotting fungi. Furthermore, the relationship between the elution amount of Ag ⁺ ions, the amount of .OH radicals, and the survival rate of the wood-rotting fungi was determined for the three species of Streptomyces mushroom and Kawatake mushroom, as shown in FIGS. 9 and 10.

From this, it was found that the survival rate of wood-rotting fungi decreased with an increase in the amount of Ag ⁺ ion eluted and the amount of .OH radicals. With the elution of Ag ⁺ ions from
It was presumed that OH radicals were generated, and the wood rot fungi were killed by the sterilizing ability of the OH radicals, and it was confirmed that the rot radicals were proportionally quantitative.

The sterilization of wood rot fungi by the .OH radicals leads to the elution of silver ions due to the presence of water invading the wood tissue, and the function works only when water invades. Otherwise, the zeolite continues to carry silver ions in the lattice, so that the sterilizing ability is constantly maintained.

The present invention based on the above-mentioned action mechanism can be mainly applied to the foundations, pillars, and wall materials of buildings, civil engineering works, and the like. It can be widely used for products.

[0020]

EXAMPLE A zeolite A having an average particle size of 2 microns was immersed in a dilute solution of silver nitrate, and replaced with silver ions.
A 3 WT% silver ion exchange type A zeolite was prepared. on the other hand,
We chose sawara as wood and this was 50mm × 50mm ×
It was cut to 10 mm. Next, the wood was put into a closed container, and a vacuum pump was operated to evacuate the container to 20 mmH.
g, and a dispersion obtained by mixing the silver ion-exchanged A-type zeolite to a concentration of 50 g / L was charged therein.
Wood was immersed in the aqueous solution. Then, the container was pressurized to 5 kg / cm 2 with a pressure pump and maintained for 30 minutes. The wood was taken out of the container and left in the shade at room temperature for one week to air dry.

On the other hand, a liquid is prepared in which Streptomyces mushroom strain cultured and grown in a constant temperature bath at 27 ° C. is dispersed, and the above-mentioned solution is added to the wood impregnated with the silver ion-exchanged type A zeolite.
0 ml was added dropwise.

The results of a follow-up study of the change in the wood over time were as follows.

[Table 1]

[0023]

The present invention has the following effects based on the above configuration and operation. (1) When moisture invades wood such as building materials and earth and wood due to dew condensation, etc., it is attracted by the moisture and silver ions carried on the zeolite are eluted, resulting in high sterilizing power of OH radicals generated by the silver ions. Thus, the wood rot fungus is killed, the propagation of the rot fungus is suppressed, and the termites are completely harmless. (2) In addition, the sterilization ability of Ag + ions is maintained in a state of being carried on zeolite as long as there is no intrusion of water due to dew condensation or the like, so that the effect can be maintained semipermanently. Conventional preservatives evaporate and expire in 4-5 years, but have a significantly longer life. (3) Furthermore, zeolite and silver ion have no volatility, and have no harm even when used for living wood where humans live.
There are no heavy metals that can harm the human body when dismantled and recycled.

[Brief description of the drawings]

FIG. 1 is a diagram showing a change in the elution amount of silver ions.

FIG. 2 is an ESR measurement diagram showing the expression of a radical.

FIG. 3 is an ESR measurement diagram showing the expression of radicals.

FIG. 4 is a graph showing the relationship between the amount of silver ion eluted and the amount of .OH radicals generated.

FIG. 5 is a graph showing a change in the survival rate of Pleurotus ostreatus.

FIG. 6 is a graph showing a change in the survival rate of Kawatake mushrooms.

FIG. 7 is a graph showing the relationship between the amount of silver ion eluted and the survival rate of wood-rotting fungi.

FIG. 8 is a graph showing the relationship between the generation amount of OH radicals and the survival rate of wood rot fungi.

FIG. 9 is a graph showing the relationship between the amount of silver ions eluted and the amount of generation of .OH radicals and the survival rate of wood-rotting fungi when silver ions are added to Japanese quail mushrooms.

FIG. 10 is a graph showing the relationship between the amount of silver ions eluted and the amount of generation of .OH radicals and the survival rate of wood rot fungi when silver ions are added to Kawatake mushrooms.

FIG. 11 is a diagram showing the taxonomic position of rot fungi.

Claims (4)

[Claims] 1. A wood tissue is impregnated with zeolite carrying silver ions having a particle size of 500 microns or less, and hydroxyl radicals generated by the action of water and silver ions eluted when water enters the wood. Wood which is characterized by sterilizing wood rot fungi by OH). 2. A zeolite capable of being impregnated in a wood tissue is prepared, silver ions are supported on the zeolite by ion exchange or impregnation, and the target wood is subjected to reduced pressure, pressure, ultrasonic vibration, and rubbing. A method for producing wood, comprising infiltrating the zeolite into an internal tissue by at least one of the means. 3. The wood according to claim 1, wherein the zeolite is a type A synthetic zeolite. 4. The method for producing wood according to claim 2, wherein the zeolite is an A-type synthetic zeolite.