JP2564466B2 - Wood preservative - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wood-fixing type water-soluble wood preservative.

[0002]

2. Description of the Related Art Conventionally, as a wood-fixing type water-soluble wood preservative, chromium, copper, and arsenic compound-based CCA (JIS
K 1554) is the mainstream. When CCA is injected into wood, a chromium compound chemically reacts with a copper compound and an arsenic compound due to a redox reaction by wood components,
It turns into water-insoluble matter and sticks to wood. Therefore, CCA has high water resistance and leaching resistance, and can be expected to maintain its efficacy over a long period of time. However, since CCA contains harmful heavy metals such as chromium (hexavalent chromium) and arsenic, toxicity to humans and animals and environmental pollution have become social problems.

Therefore, a quaternary ammonium salt (eg, didecyldimethylammonium chloride, N-alkylbenzylammonium chloride) which is a cationizing agent is used as an alternative to this CCA.

[0004]

However, since the quaternary ammonium salt, which is a cationizing agent, is water-soluble and has poor water resistance, it is easily leached into water even if it is injected into wood as a wood preservative, It was restricted to be used outdoors where rainwater or the like acts, or where it is constantly exposed to water.

The present invention has been made in view of the above points, and can be applied to wood without fear of leaching with water, and is excellent in insect / insecticidal performance, antiseptic / mildew performance and dimensional stabilization of wood. It is also intended to provide an excellent wood preservative.

[0006]

The wood preservative according to the present invention is a cation composed of chitosan and a quaternary ammonium salt.
It is characterized in that it is mainly composed of cationized chitosan obtained by reacting with an agent .

[0007] hereinafter, the present invention will be described in detail. As the cationized chitosan, which is the main component of the wood preservative according to the present invention, those obtained by reacting chitosan with a cationizing agent can be used.

[0008] Chitosan is obtained by deacetylating chitin, which is one of the polysaccharides abundantly contained in the shells of crustaceans such as crabs and shrimps and the shells of insects, and has a chemical structure of The skeleton is a natural polymeric material very similar to cellulose, which is a fiber component of wood. In the present invention, chitosan can be used without particular limitation as long as it has a deacetylation degree of 50 to 90 and a molecular weight of 500 or more, but if possible, a low molecular weight of 50,000 or less is preferable, and a molecular weight of 20,000 is particularly preferable. The following are still preferred. Also, oligochitosan having a molecular weight of 10,000 or less can be used.

In the present invention, almost any cationizing agent having a reactive group can be used as the cationizing agent. For example, a cyclic structure represented by the chemical formula (1) such as epichlorohydrin of the chemical formula (2) can be intramolecularly used. Those having in can be used relatively easily.

[0010]

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And as a cationizing agent in the present invention
Has high insect-proof / ant-proof and antiseptic / mold-proof performance, and is CC
Highly safe quaternary ammonium with no toxicity like A
It is preferable to use a salt, and to divide the cyclic structure of the chemical formula (1).
As a quaternary ammonium salt contained in the child, the chemical formula
Glycidyl trimethyl ammonium chloride represented by (3)
Loride can be mentioned as a typical example. Well
Of octopus glycidyl trimethyl ammonium chloride
In addition, glycidyltriethylammonium chloride,
Glycidyl tristearyl ammonium chloride
R of chemical formula (4) ¹ , R² , R³ Variously changed
Various compounds can also be used (however, chemical formula (4)
In, k, m, and n are preferably integers of 1 to 12,
k, m and n may be the same or different).

[0012]

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The method for reacting chitosan with a cationizing agent to prepare cationized chitosan is not particularly limited, but it can be carried out, for example, as follows. First, a certain amount of chitosan is weighed and isopropyl alcohol (80% by weight concentration aqueous solution) in an amount 7 to 10 times the weight of chitosan is added. And the temperature is 50-60 ℃
, And the cationizing agent of the same weight as chitosan is gradually added thereto with stirring. After this, stirring 5 to 5
The desired cationized chitosan can be produced by reacting for 6 hours. Here, for example, when chitosan is reacted with the cationizing agent represented by the chemical formula (4), the amino group of chitosan reacts with the cyclic structure of the cationizing agent to bond with the structure as shown in the chemical formula (4) to form cationization. This is what produces chitosan.

[0014]

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The cationized chitosan thus produced can be filtered by a glass filter, gauze or the like, repeatedly washed with isopropyl alcohol (80% by weight aqueous solution) and dried before use. Instead of the isopropyl alcohol, alcohols that dissolve in water at an arbitrary ratio such as ethyl alcohol and methyl alcohol can be used.

The cationized chitosan thus obtained can be used as a wood preservative by directly diluting it with water in the case of fine particles such as powder, and in the case of flakes, a small amount of it can be used. It can be easily dissolved in water by adding an organic acid or an inorganic acid to be used as a wood preservative. By impregnating wood with the thus-prepared wood preservative, the cationizing agent in the cationized chitosan can exert excellent insect-controlling / insecticidal performance and antiseptic / mold-proofing performance. In addition, chitosan has a chemical skeleton structure similar to that of cellulose and has high adhesion to wood fibers. Therefore, cationized chitosan has high water resistance and leaching resistance, and can maintain its efficacy over a long period of time. Is. Furthermore, the action of chitosan can enhance the dimensional stability of wood.

[0017]

The invention will now be illustrated by the examples. (Example 1) 140 g of isopropyl alcohol (80% by weight concentration of aqueous solution) was added to chitosan (molecular weight of 10000 to 1000).
50000, Deacetylation degree about 87) 20g was added,
The liquid temperature was raised to 60 ° C. and left for 30 minutes. Next, 20 g of glycidyl trimethylammonium chloride (80% by weight aqueous solution) was gradually added with stirring, and the stirring was repeated for another 5 hours after the addition was completed. After completion of the reaction, the mixture was filtered through a glass filter, washed repeatedly with a large amount of isopropyl alcohol (80% by weight aqueous solution), and dried in a circulating oven at 40 ° C to obtain about 30 g of cationized chitosan. It was

Example 2 About 30 g of cationized chitosan was obtained in the same manner as in Example 1 except that ethyl alcohol (80% by weight concentration aqueous solution) was used instead of isopropyl alcohol in Example 1. It was Example 3 About 30 g of cationized chitosan was prepared in the same manner as in Example 1 except that glycidyltriethylammonium chloride (80% by weight aqueous solution) was used instead of glycidyltrimethylammonium chloride of Example 1. Obtained.

(Indoor antiseptic efficacy test) The flaky cationized chitosan obtained in Example 1, Example 2 and Example 3 was dissolved in a 0.5 wt% acetic acid aqueous solution to prepare a test solution.
The cationized chitosan concentration of the test solution is 0.25% by weight,
0.50% by weight, 1.00% by weight, 2.00% by weight,
Five kinds of 3.00% by weight were prepared. Then, using this test solution, a test wood was prepared in accordance with JIS A 9201 and weather-proofed. After that, the test wood was left to stand for 3 months in the fungus of Kawaratake and Aedes aureus, and the weight at that time was measured. The reduction rate was calculated. For comparison, the same test was carried out for the case of using chitosan alone and the case of using glycidyltrimethylammonium chloride alone, and also for the untreated wood. The results are shown in Table 1.

[0020]

[Table 1]

As shown in Table 1, in Examples 1 to 3, the average weight loss rate of 3% or less, which is the JIS standard value, can be achieved at a concentration of 1.00% by weight. Is confirmed to be highly effective. On the other hand, in the case of using chitosan or glycidyltrimethylammonium chloride alone, the standard could not be met within the range of the concentration tested.

(Indoor antitermite efficacy test) The flaky cationized chitosan obtained in Example 1 was dissolved in a 0.5 wt% acetic acid aqueous solution to give cationized chitosan concentrations of 0.50 wt% and 1.00 wt. %, 2.00% by weight, 3.00% by weight, and 5.00% by weight, five kinds of test liquids were prepared. Using this test solution, a test wood was prepared according to the Japan Wood Preservation Association Standard No. 11 (1) method, and an ant-terminating effect test was conducted. For comparison, the same test was carried out for the case of using chitosan alone and the case of using glycidyltrimethylammonium chloride alone, and also for the untreated wood. Table 2 shows the results.

[0023]

[Table 2]

As can be seen from Table 2, in Example 1, it is possible to achieve an average weight loss rate of 3% or less, which is a conformance criterion of the Japan Wood Preservation Association standard, at a concentration of 3.00% by weight. It can be confirmed that it is effective as a wood preservative. On the other hand, in the case of using chitosan or glycidyltrimethylammonium chloride alone, the standard could not be met within the range of the concentration tested.

(Weather resistance test) The flaky cationized chitosan obtained in Example 1 was dissolved in a 0.5 wt% acetic acid aqueous solution to give cationized chitosan concentrations of 1.00 wt% and 2.0.
Five kinds of test liquids of 0% by weight, 3.00% by weight, 4.00% by weight and 5.00% by weight were prepared. Then, this test liquid was poured into a cedar test material having a 5 cm square shape and a length of 30 cm (two-necked claw, sapwood ratio of about 40% at the wood edge). After drying this for 3 weeks indoors, it was left outdoors in a place where it was exposed to rainwater and exposed to direct sunlight, and after 90 days, the state of cracks occurring at the wood mouth and the width of the cracks occurring were measured. For comparison, one using chitosan alone,
The same test was carried out for glycidyl trimethyl ammonium chloride used alone, and the same test was also carried out for untreated wood. The results are shown in Table 3. In addition, in the column of "Crack generation density" in Table 3, "++" cracks on the entire surface of the wood opening, "++" cracks on about 1/2 of the wood opening, and "+" indicates 1/3 of the wood opening.
Cracks occur to some extent, and “±” means that cracks occur slightly at the wood mouth.

[0026]

[Table 3]

As shown in Table 3, in Example 1, the occurrence of cracks on the wood mouth surface was significantly suppressed at a concentration of about 2.00 to 3.00% by weight, and the effect of dimensional stabilization was obtained. It is confirmed that there is. On the other hand, in the case of using chitosan alone, the effect of suppressing cracking on the xylem surface is observed at a concentration of 3.00% by weight, but the effect is smaller than that of Example 1, and glycidyl trimethyl ammonium chloride is used alone. No efficacy was observed for those used in.

[0028]

As described above, according to the present invention, the chitosan and the fourth
React with cationizing agent consisting of primary ammonium salt
Since the wood preservative was prepared mainly with the cationized chitosan obtained by the above, the cationizing agent in the cationized chitosan can exert excellent insect / insecticidal performance and antiseptic / mold prevention performance. The chitosan in the cationized chitosan has high adhesiveness to the wood fiber and high water resistance and high leaching resistance, and is capable of maintaining the effect as a wood preservative for a long period of time. is there. Furthermore, the chitosan in the cationized chitosan can also increase the dimensional stability of wood. Also consists of quaternary ammonium salts
Cation agents are not as toxic as CCA and are highly safe.
It is a good thing.

Claims (1)

(57) [Claims] 1. A composition comprising chitosan and a quaternary ammonium salt.
A wood preservative, which is mainly composed of a cationized chitosan obtained by reacting with a cationizing agent.