JPH06247815A - Boric acid composition and wood-preserving agent - Google Patents

Abstract

PURPOSE:To maintain the potencies of boric acid, such as antimicrobial force, an insecticidal force and a flame-resistant effect over a long period on the surface of wood treated therewith. CONSTITUTION:A boric acid composition is prepared from a boric acid-chitosan complex and used as a wood-preserving agent. The boric acid is stabilized by the adhesive property of the chitosan to wood, and can be adhered to the wood.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a boric acid composition and a wood preservative containing the boric acid composition as a main component.

[0002]

BACKGROUND OF THE INVENTION Boric acid has a strong bactericidal activity and insecticidal activity, and has been conventionally used for the prevention and control of flat beetles that occur on plywood and the like, and the control of termites that occur on wood. Boric acid is also widely used as a flame retardant for wood because it has a high flame retardant effect. The treatment of wood with boric acid is generally carried out by dissolving boric acid in water or the like and spraying or injecting it.

[0003]

However, since boric acid is water-soluble, even if it is treated on wood, it will be eluted by water depending on the place of use, especially on the outdoor surface of houses, outdoor structures,
There has been a problem that the effect of boric acid cannot be maintained for a long period of time in a place such as an outdoor playground that is easily affected by rainwater.

The present invention has been made in view of the above points, and boric acid composition capable of retaining the sterilizing power, insecticidal power, flame retardant effect and the like of boric acid on the surface of treated wood for a long period of time. The object is to provide a product and a wood preservative.

[0005]

The boric acid composition according to the present invention is characterized by comprising a complex of boric acid and chitosan. This boric acid composition contains 0.1 to 0.5 parts by weight of chitosan and 0.5 parts by weight of acid per 1 part by weight of boric acid.
It can be prepared as containing less than parts by weight.

The boric acid composition according to the present invention is characterized in that it comprises a complex of boric acid and chitosan and a polyhydric alcohol. This boric acid composition is prepared as 0.1 to 0.5 parts by weight of chitosan, less than 0.5 parts by weight of acid, and 1 to 1.5 parts by weight of polyhydric alcohol per 1 part by weight of boric acid. be able to.

As the polyhydric alcohol, a polyhydric alcohol having an amino acid in the molecule can be used.
Furthermore, the wood preservative according to the present invention is characterized by comprising these boric acid compositions. Hereinafter, the present invention will be described in detail.

[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. This chitosan is used as a preservative for foods and cosmetics because it has an antibacterial effect against some fungi. Further, chitosan has a chemical skeleton structure very similar to that of cellulose as described above, and therefore has excellent adhesiveness to fibers, and this property is used for the production of antibacterial fibers or as a fabric softener. It has been applied. In the present invention, chitosan having a deacetylation rate of about 50 to 90% is preferable, and if the molecular weight is 500 or more, it can be used without particular limitation, but if possible, it is preferably a low molecular weight compound having a molecular weight of 50,000 or less. Those having a molecular weight of 20,000 or less are more preferable.

In the present invention, boric acid is reacted with this chitosan to prepare a boric acid composition as a complex of boric acid and chitosan. By using boric acid as a chitosan complex in this way, boric acid can be stably fixed to wood because of the high adhesion of chitosan to wood. This boric acid composition comprising a complex of boric acid and chitosan has a chitosan content of 0.1 parts by weight per 1 part by weight of boric acid.
It can be prepared as containing 1 to 0.5 parts by weight and less than 0.5 parts by weight of acid. Although chitosan is not soluble in water, it forms a salt in the presence of an acid and dissolves in water, and in such a state of being dissolved in water, chitosan easily reacts with boric acid to form a complex. Therefore, it is preferable to use an acid when preparing a boric acid composition comprising a complex of boric acid and chitosan. However, depending on the case, it is not always necessary to use the acid, and there is a case where the acid is not used.
As this acid, organic acids such as acetic acid, formic acid, lactic acid, citric acid, adipic acid, tartaric acid, oxalic acid, and inorganic acids such as hydrochloric acid can be used. Almost all organic acids can be used, and most inorganic acids can be used, but sulfuric acid cannot be used.

Further, in the present invention, a boric acid composition composed of a complex of boric acid and chitosan and a polyhydric alcohol can be prepared. By adding a polyhydric alcohol, the solubility of boric acid can be increased and the boric acid composition can be stabilized. The polyhydric alcohol is not particularly limited, and examples thereof include ethylene glycol, diethylene glycol, polyethylene glycol, polyethylene glycol methacrylate, propylene glycol, and glycerin. Among them, polyethylene glycol is particularly excellent in the dimensional stabilizing action of wood. Desirable for. When polyethylene glycol is used, its molecular weight is preferably 400 or more, more preferably 400 to 2000 in terms of workability.

This boric acid composition comprising a complex of boric acid and chitosan and a polyhydric alcohol comprises 0.1 to 0.5 parts by weight of chitosan, less than 0.5 parts by weight of acid, and polyhydric alcohol per 1 part by weight of boric acid. It can be prepared as containing 1 to 1.5 parts by weight of alcohol. As the polyhydric alcohol, those described above such as polyethylene glycol can be used, but in the present invention, it is more preferable to use a polyhydric alcohol having an amino group in the molecule. As the polyhydric alcohol having an amino group, for example, triethanolamine can be used. When a polyhydric alcohol having an amino group in the molecule is thus used, boric acid, chitosan, and a polyhydric alcohol having an amino group in the molecule react with each other to form a complex with water as a medium. The boric acid composition can be prepared as a water-soluble and stable viscous liquid. The amount of chitosan or acid with respect to boric acid and the polyhydric alcohol having an amino group in the molecule is the same as above, but 0.2 to 0.3 parts by weight of chitosan and 0.2 parts by weight of organic acid per 1 part by weight of boric acid. ~ 0.3 parts by weight, polyhydric alcohol having an amino group in the molecule 1.1
It is more preferable that the amount is 1.2 parts by weight. Further, since water is required at the initial stage of the reaction between boric acid and chitosan, it is preferable to add 3 to 5 parts by weight of water to 1 part by weight of boric acid.

The boric acid composition according to the present invention can be easily produced, for example, by the following method. of course,
It goes without saying that the method is not limited to the following method. First, add chitosan to an aqueous solution of organic acid, and add 60 to 80 ° C.
Completely dissolve it with stirring, and then gradually add boric acid with stirring to dissolve it substantially at 75 to 85 ° C. Finally, add a polyhydric alcohol having an amino group in the molecule preheated to 75 to 85 ° C. The boric acid composition can be prepared by adding and completely dissolving at 75 to 85 ° C.

The boric acid composition prepared as described above can be used as a wood preservative. This wood preservative according to the present invention is applied to wood, or by injecting under pressure or the like, by the action of boric acid, wood receives damage from termites, bark beetles, flat beetles and the like, and from wood decay fungi. It is possible to prevent the decay and the discoloration caused by the fungi, and also to prevent the damage such as the dimensional change and the crack due to the burning of the wood due to the fire or the absorption and desorption of the moisture. In addition, since boric acid forms a complex with chitosan, boric acid can be stably adhered to wood due to the high adhesion of chitosan to wood, and boric acid is washed away from wood by the action of rainwater. It is possible to prevent the wood from being destroyed, and the preservation effect of wood by boric acid can be maintained for a long time.

[0014]

EXAMPLES The present invention will now be illustrated by examples. (Example 1) 62.5 g of water was added to 3 g of acetic anhydride to obtain 65
After heating to ℃, chitosan (deacetylation degree 87%,
3 g of average molecular weight of about 48,000) was added and completely dissolved. Next, 15 g of boric acid was added thereto, and the mixture was heated to 75 ° C. and stirred to substantially dissolve it. Finally, 16.5 g of triethanolamine preheated to 75 ° C. was added and completely dissolved to obtain a boric acid composition. The boric acid composition was a viscous liquid and did not cause precipitation or the like even when left for a long time. Further, it could be diluted with water at an arbitrary ratio.

(Example 2) 62 g of water was added to 4 g of acetic anhydride and heated to 65 ° C., and 4 g of chitosan (deacetylation degree 87%, average molecular weight about 48,000) was added thereto and completely dissolved. Next, 10 g of boric acid was added thereto, and the mixture was almost dissolved by stirring while heating to 75 ° C. Finally, polyethylene glycol 20 preheated to 75 ° C
g was added and completely dissolved to obtain a boric acid composition. The boric acid composition was a viscous liquid and did not cause precipitation or the like even when left for a long time. Further, it could be diluted with water at an arbitrary ratio.

(Example 3) 73 g of water was added to 4 g of acetic anhydride and heated to 65 ° C., and 8 g of chitosan (deacetylation degree 87%, average molecular weight about 48,000) was added thereto and completely dissolved. Next, 15 g of boric acid was added to this, and the mixture was completely dissolved by stirring while heating at 75 ° C. to obtain a boric acid composition. The boric acid composition was a viscous liquid and did not cause precipitation or the like even when left for a long time.
Further, it could be diluted with water at an arbitrary ratio.

Example 4 10 g of water was added to 50 g of polyethylene glycol (average molecular weight 600) and heated to 85 ° C., 10 g of boric acid was added thereto, and immediately chitosan (deacetylation degree 87%, average molecular weight about 48,000). )
3 g was added and completely dissolved by stirring while heating at 90 ° C. Finally, 27 g of water was added to obtain a boric acid composition. The boric acid composition was a viscous liquid and did not cause precipitation or the like even when left for a long time. Further, it could be diluted with water at an arbitrary ratio.

(Weather resistance test) The boric acid composition obtained in Example 1 was diluted with water so that the concentration of boric acid was 0.2% by weight,
4 wt%, 0.6 wt%, 1.0 wt% wood preservatives were prepared. This wood preservative was injected under reduced pressure into cedar sapwood prepared to have dimensions of 2 cm × 2 cm × 1 cm to prepare test materials. The injection amount of each test material is shown in the column of boric acid absorption amount in Table 1. This test material is cooled to room temperature with water (the amount of water is 10% of the total volume of the test material).
After leaching treatment by immersing in (double volume) for 8 hours and stirring, put into an oven at 40 ° C for 16 hours to perform volatilization treatment (this leaching treatment and volatilization treatment operation is called weatherproof operation) The weathering operation was repeated 10 times to measure the residual amount of boric acid in each test material. The remaining amount of boric acid is measured for each number of operations,
The results are shown in Table 1.

For comparison, a wood preservative having a concentration of 0.4% by weight and 0.6% by weight (Comparative Example 1) was prepared by diluting boric acid with water, and similarly depressurized to cedar sapwood. A test material was prepared by injection, and weathering operation was performed to measure the residual amount of boric acid. The results are shown in Table 1.

[0020]

[Table 1]

As shown in Table 1, in Comparative Example 1 in which boric acid was dissolved in water and used as a wood preservative, leaching of boric acid occurred remarkably, but a wood preservative prepared with a chitosan complex of boric acid. In Example 1 using
It is confirmed that the leaching of boric acid is considerably suppressed. (Preservative efficacy test) Example 1 prepared in the above (weather resistance test)
Also, using the test material of Comparative Example 1, the test materials were planted with Pleurotus ostreatus (brown rot fungus: TYP) and Kawaratake (white rot fungus: COV) to test the antiseptic effect. The test was carried out on each of the test materials that were not subjected to the weather resistance operation in the above “weather resistance test” and the test materials that were subjected to the weather resistance operation 10 times. The test of antiseptic effect was conducted based on JIS A 9102, and the weight reduction rate of the test material was measured. For comparison, a test material not treated with boric acid was also tested, and the weight reduction rate was measured in the same manner. The results are shown in Table 2.

[0022]

[Table 2]

As can be seen from Table 2, in Comparative Example 1, the weight loss rate of the test material subjected to the weathering operation is significantly higher than that of the test material not subjected to the weathering operation, and the antiseptic effect is remarkable due to the leaching of boric acid. However, in Example 1, there is no significant difference in the weight reduction rate between the test material that is not weather-proofed and the test material that is weather-proofed, and the leaching of boric acid is suppressed, and the antiseptic effect is suppressed. Is confirmed to be held.

(Dimensional stability test) The boric acid composition obtained in Example 2 was diluted with water so that the concentration of boric acid was 0.4% by weight,
A 6% by weight wood preservative was prepared. 5 of this wood preservative
50% water content created in dimensions of cm x 5 cm x 20 cm
Injected under reduced pressure into Japanese cedar sapwood, boric acid absorption is 2.9kg
/ M ^3, to prepare a test material of 4.2kg / m ^3. When each of the test materials and the test material not subjected to the treatment were left outdoors with good ventilation, the test material into which the wood preservative was injected had very few cracks in the wood mouth as compared with the untreated test material.

(Termite control test) The boric acid composition obtained in Example 1 was diluted with water so that the concentration of boric acid was 0.4% by weight,
Prepare 6% by weight of wood preservative and add 1 c of this wood preservative
A test material was prepared by injecting under reduced pressure into Japanese red pine sapwood prepared to have dimensions of m × 1 cm × 2 cm. For comparison, a wood preservative having a concentration of 0.4% by weight and 0.6% by weight (comparative example 1) was prepared by diluting boric acid with water, and was similarly vacuum-injected into cedar sapwood. A test material was created. A test material not subjected to the weather resistance operation in the above-mentioned "weather resistance test" and a test material subjected to the weather resistance operation 10 times were used, and a dental plaster having a thickness of 5 mm and a diameter of 10 cm.
× Installed in the center of a cylinder with a height of 5 cm, after inserting 150 termite termite workers and 15 soldier ants, place them on wet absorbent cotton (Company) based on Japan Wood Preservation Association Standard No. 11 (1) A feeding damage test was performed to measure the weight loss rate of the test material. For comparison, a test material not treated with boric acid was also tested, and the weight reduction rate was measured in the same manner. The results are shown in Table 3.

[0026]

[Table 3]

As can be seen from Table 3, in Comparative Example 1, the weight reduction rate of the test material subjected to the weathering operation was significantly higher than that of the test material not subjected to the weathering operation, and the termite-proof effect was obtained by the leaching of boric acid. Although it is remarkably reduced, in Example 1, there is no significant difference in the weight reduction rate between the test material which is not weather-proofed and the test material which is weather-proofed, and the leaching of boric acid is suppressed, and It is confirmed that the ant effect is maintained.

(Field ant / preservative efficacy test) The boric acid compositions obtained in Examples 3 and 4 were diluted with water to give boric acid concentrations of 0.1% by weight, 0.2% by weight and 0.4% by weight. %, 0.6
A wt% wood preservative was prepared. 3c of this wood preservative
It was injected under pressure into a red pine sapwood pile with a sharp tip measuring mx 3 cm x 35 cm, and the amount of boric acid absorbed was 0.7 kg / m ² ,
0.8 kg / m ² , 1.1 kg / m ² , 2.4 kg / m
² , 2.6 kg / m ² , 3.4 kg / m ² , 3.7 kg
A test material of / m ² was prepared. Field tests were conducted by burying each of the test materials and the test material not subjected to the treatment up to a depth of 30 cm around the nesting of the termite nests in the black pine forest at Fukiagehama, Fukiage-cho, Hioki-gun, Kagoshima Prefecture. For comparison, boric acid was diluted with water to prepare wood preservatives (Comparative Example 2) having concentrations of 0.1% by weight, 0.2% by weight, and 0.6% by weight,
Similarly, a test material was prepared by injecting pressure into Japanese pine sapwood, and a field test was conducted in the same manner. The evaluation results of the field test are shown in the "damage situation" column of Table 4. The damage condition was evaluated by giving scores to the five test materials as follows and calculating the average value. 0 points: No scratches or decay on the surface of the test material. 1 point: There is a slight dent or decay on the surface of the test material. 2 points: There is obvious food damage or decay on the surface of the test material. 3 points: Eating damage or decay on the surface of the test material has progressed to the inside. 4 points: The entire test material is damaged by food or decay. 5 points: The test material is destroyed by food damage or decay.

[0029]

[Table 4]

As shown in Table 4, the damage of Comparative Example 2 was large in the first year and then in the second year, and the ant-preservation and antiseptic effects were remarkably lowered by the leaching of boric acid. In Examples 3 and 4, it is confirmed that the leaching of boric acid is suppressed and the ant / preservative efficacy is maintained.

[0031]

As described above, the wood preservative of the boric acid composition comprising the chitosan complex of boric acid can prevent feeding damage by pests due to the action of boric acid, decay by wood-destroying fungi, discoloration by fungi, etc. It is possible to prevent damage of dimensional change due to burning of wood and absorption and desorption of water, and moreover, due to the high sticking property of chitosan to wood, boric acid can be stably stuck to wood. The preservation effect of these woods can be maintained for a long period of time.

Claims (6)

[Claims] 1. A boric acid composition comprising a complex of boric acid and chitosan. 2. Chitosan is added to 1 part by weight of boric acid.
The boric acid composition according to claim 1, which comprises 1 to 0.5 parts by weight and less than 0.5 parts by weight of the acid. 3. A boric acid composition comprising a complex of boric acid and chitosan and a polyhydric alcohol. 4. Chitosan is added to 1 part by weight of boric acid.
The boric acid composition according to claim 3, comprising 1 to 0.5 parts by weight, less than 0.5 parts by weight of the acid, and 1 to 1.5 parts by weight of the polyhydric alcohol. 5. The boric acid composition according to claim 3, wherein a polyhydric alcohol having an amino acid in the molecule is used as the polyhydric alcohol. 6. A wood preservative comprising the boric acid composition according to claim 1.