JP2729738B2 - Wood preservatives, preservative wood and methods for improving wood - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention replaces preservatives, such as CCA, which are recently toxic to humans, with boric acid having low toxicity to humans and chitin, which is a constituent material of cereals, which is a natural material. TECHNICAL FIELD The present invention relates to a preservative which is almost harmless to humans and acetylation of wood and a method of applying the same, by molecularly designing a polysaccharide such as chitosan which is a substance derived from glycerol.

[0002]

2. Description of the Related Art Wood is a natural material, so it "rots"
Because of the fateful disadvantages of going crazy and burning,
For "rot", creosote, chrome,
Copper, arsenic, bis (n-tributyltin) oxide and γ
-Prevention of bacteria, fungi and insects by imparting water repellency to the treated material by adding paraffin and a surfactant to a preservative made of BHC.

[0003] Solvents having good preservative ability have a slow evaporation, a boiling point of 260 ° C to 320 ° C, and a viscosity of 20 CP (20 ° C).
The following are suitable as gas oil,
Light oils, high boiling lighting oil fractions and the like are used, but if the boiling point is high, there is a problem that the permeation is good but the drying property of the treated material is poor.

[0004] For imparting residual effect, a method of adding a substance which is difficult to volatilize such as paraffins and glycols is known. To prevent blooming, esters such as dioctyl phthalate and propylene glycol are used. Compounds with good solubility are known.

[0005]

On the other hand, the constituents of these drugs are toxic, and there is a problem for humans in terms of work safety.

[0006] The treatment of waste wood whose service life has passed has a very large adverse effect on animals and plants from the viewpoint of environmental protection, such as generation of highly toxic gas and elution of heavy metals. There is no doubt that the treatment of this will cause social problems.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve these problems, and has an object to solve the above problems.
A chitooligosaccharide consisting of 20 to 3,200, a heterosaccharide of 2.5-andromannose and a molecular weight of 3,200 to 4,
8,000 low molecular weight chitosan is complexed with or reacted with boric acid, and these liquids and powders are subjected to various methods, for example, vacuum impregnation or high pressure injection.
This is a method for producing antibacterial, antifungal and insect repellents, characterized by immobilization and stabilization in wood cells by immersion and impregnation.In addition, acetylation of wood is performed in combination with acetic acid, preservative effect, An object of the present invention is to provide a method of improving the defect of "going out of order", making the wood flame-retardant, and furthermore, chemically bonding and immobilizing these effective substances to wood constituents.

The cell walls and proteoglycans of decay fungi, termites, fungi, molds, arthropods, etc., have chitin as a building material of these, and a series of these fungi,
Molds and arthropods decompose cellulose, hemicellulose, starch, and pectin, which are constituents of wood, using cellulase, pectinase, and formic acid, and ingest them.

[0009] Chitosan having a molecular weight of 320 or more and 48,000 or less, a low molecular weight chitosan and a chitooligosaccharide having a molecular weight of not less than 48,000, and a heterosaccharide of 2.5-anhydromannose, which is used as a controlling agent, has a pH of 4 to 4 depending on an organic acid and an inorganic acid. 7 and the concentration is preferably adjusted to a range of 0.01 to 5% by weight, and the aqueous solution of chitosan, chitooligosaccharide and 2.5-anhydromannose adjusted in this manner is used in an amount of 20%. Heating within ℃ ~ 90 ℃,
While stirring, boric acid is converted into a chain or bound to each functional group in the chitosan molecule.

[0010] The sugar chain in which the complex has been generated dissolves in the solution and becomes an effective preservative. On the other hand, when boric acid binds to the amino group in the sugar chain, it precipitates in the solution and precipitates, so it is desirable to remove it with a centrifuge or the like. This is because the substance is difficult to be impregnated and introduced.

The impregnation of wood is performed by suspending the wood in these solutions and impregnating it by vacuum and pressure or spray coating the surface of the wood and evaporating it or drying it with alcohols, phenols or petroleum-related substances. By
Low molecular weight chitosan, chitooligosaccharide and 2.5-anhydromannose are precipitated and immobilized in wood cells.

[0012]

[Action] Starch, cellulose and hemicellulose constituting wood are homopolymeric acidic polysaccharides, and there are trace amounts of organic metals such as copper, manganese and iron.

On the other hand, when the molecular weight is 320 or more and 48,0
Heterosaccharides of low molecular weight and chitooligosaccharide 2.5-anhydromannose of not more than 00 are heteropolysaccharides composed of a cationic polysaccharide having an isoelectric point around pH 8.5, 2.5-anhydromannose and oligosaccharide. And has an affinity for wood.

As for the molecular structure, cellulose has a carboxyl group at the C-5 position and a hydroxyl group at the C-3 position.
Carboxyl group at position 5 and hydroxyl group at position C-3
Has a similar structure with an amino group charged to a strongly reactive cation at the position, but chemically treated chitosan further has 2.5-anhydromannose which constitutes an alkyl group at the molecular chain terminal. The wood has biocompatibility and stability in vivo.

On the other hand, chitosan alone has been reported to have antibacterial activity per D-glucosamine heptasaccharide, but as for antifungal, those having a reduced molecular weight of 48,000 or less have been reported to have antifungal activity. ing.

Observation of these antibacterial and antifungal actions with a scanning electron microscope reveals that fungi and typical wood rot fungi, "Kawaratake", "Namidatake", and "Ozuratake" are converted into chitosan whose molecular structure has been changed by deacetylation. On the other hand, when they try to break them down and try to invade wood, filamentous fungi that have chitin as a structural substance and `` Kawataketake '', `` Namidatake '', and `` Ouzutaketake '' dissolve their own hyphae and glucan by enzymes secreted by them. The growth function has been stopped.

In particular, it has been reported that low-molecular-weight chitosan has an amino group at the C-2 position, has a structure similar to that of the antibiotics kanamycins, and acts on 16S ribosomal RNA of prokaryotic cells to specifically inhibit ribosome translation. ,Also,
Since it acts on guanosine, which works to cleave exons 5 'of the intron of group 2 known as one of the ribozymes, and inhibits splicing, low molecular weight chitosan can recognize and work on the higher-order structure of 16S ribosomal RNA. Presumably, this is expected to work to inhibit the growth of fungi and molds.

In addition, boron has been reported as a trace element by plants, and is considered to be stable against wood. For humans, boron and boric acids are used as eyewashes and are safe.

Boric acid is known to react with compounds having hydroxyl groups in adjacent cis configuration in the structure to form a negatively charged complex. This property is often used for the separation and identification of saccharides. Used.

The molecular weight of chitosan, which is a low molecular weight compound, is 32.
Complexing with a low molecular weight chitosan and chitooligosaccharide of 0 or more and 48,000 or less, a carboxyl group at the C-5 position and a hydroxyl group at the C-3 position of the 2.5-anhydromannose heterosaccharide is Easily inferred.

These substances form a complex with the carboxyl group and the hydroxyl group of the constituent polysaccharide for fungi, molds and insects having chitin as a structural substance,
It is also conceivable to bond to an amino group, thereby inducing a feedback phenomenon of a bio-constructed substance of a constituent sugar chain of fungi, fungi, and insects, thereby inducing the molecular weight of proteoglycan on the outer surface of the shell. Furthermore, it is conceivable that these low molecular weight oligosaccharides are taken into living organisms of fungi, molds and insects and attached to genes to lower or stop the growth function.

On the other hand, although there are few reports on the mechanism of action of boron in vivo, the growth and growth of these fungi, fungi and insects having chitin in the living body due to changes in the three-dimensional structure of their constituent proteins have been reported. It is thought that growth is inhibited, and since there is no chitin in humans and animals, there is no harm, and it is speculated that it may work specifically for those having chitin as a biological building material such as fungi, molds and insects.

[0023]

【Example】

Example 1: The test sample was a piece of wood cut from the same wood, and the straight-grained portion of the cedar produced in Oita prefecture where normal growth had occurred
Fifty pieces each having a cut edge of 20 mm × 20 mm and a height of 10 mm were dried on silica gel in a vacuum desiccator for 54 hours, and further dried with a vacuum dryer to a specific gravity average of 0.31%. A piece of wood, which was stored on silica gel in a deskater, was used as a test sample for the preservative effect on cedar.

A mixture of reduced molecular weight chitosan, 2.5-anhydromannose and chitooligosaccharide was adjusted at room temperature with acetic acid at pH 5.6 as a 4% by weight aqueous solution. Next, the above aqueous solution was divided into four parts, and boric acid was added so as to be 0.2% by weight, 0.5% by weight, 1.0% by weight and 2.0% by weight with respect to the chitosan aqueous solution, and then the precipitate was filtered. As a result, a boric acid complexed chitosan aqueous solution was obtained. Using 160 ml of these test liquids per test wood, perform impregnation and impregnation for 2 hours by the aspirator vacuum impregnation method as usual, then pull up the wood, spray alcohol, and leave at room temperature for 24 hours to obtain a sample. And Table 1 shows the number of test pieces in the preservative performance test, and Table 2 shows the results of the antifungal test on cedar wood.

[0025]

[Table 1]

[0026]

[Table 2]

Example 2: Cedar raw material 1 m ³ 841 kg
And dried with a steam wood dryer to an absolute dry weight of about 368 kg. The weight of these materials is set to 43 kg / line, and then the wood is trimmed with a planer and dried. The total weight of the dried products was 368 kg / 20 pieces. The average weight of each piece was 18.4 kg. (Square cedar had no straight-grained material and the horn-shaped material was used without the core.) Same as in Example 1. PH of the water-soluble chitosan mixture
Adjusted to 5.6 and 4% by weight again.
Was prepared.

[0028]

[Table 3]

Using cedar wood impregnated with five of the above-mentioned cedar wood using a vacuum impregnation kiln, typhoon No. 17 of 1991 caused a fall of the cedar wood at a place with a fallen tree. One-third was buried underground as a test pile in a severe place
The test was started on June 1, 1998. Table 4 shows the results of the antifungal test on cedar wood pieces.

[0030]

[Table 4]

[0031]

The low molecular weight chitosan having a molecular weight in the range of 800 to 48,000 becomes a liquid which easily penetrates into the wood cytoplasm by being chained with boron, and is confirmed to be immobilized on the wood cytoplasm. Boric acid impregnated in wood cells has a growth inhibitory effect against rot fungi at a concentration of 0.8%, but when the concentration is low, boric acid is digestive toxic and shows no effect. However, when impregnated and fixed at a concentration of 0.8% or more, an effect of controlling and inhibiting arthropods (for example, cockroaches and termites) is expected.

[Table 1]

[Table 2] * The numbers indicate the number of pieces of cedar wood reduced in weight: 1.42 g / 4 cm ³ (the weight is an average value depending on the concentration of boric acid). Wood is impregnated by a vacuum impregnation method using an aspirator.

[Table 3]

[Table 4]

Claims (4)

(57) [Claims] 1. Complexing boric acid with a chitooligosaccharide having a molecular weight of 320 to 3,200, 2.5-anhydromannose, and / or a low molecular weight chitosan having a molecular weight of 3,200 to 48,000, or Wood preservatives consisting of bound compounds. 2. Chitooligosaccharides per m ^{3 of} wood 2.
Preservative wood obtained by impregnating a compound in which 5-anhydromannose and / or a low molecular weight chitosan is complexed or bonded with boron with 0.5 kg to 5.0 kg in terms of boric acid. 3. A wood preservative according to claim 1, wherein boric acid is reacted or complexed with chitosan at a weight ratio of 0.5 to 8.0. 4. An aqueous solution of a compound in which boric acid is complexed or reacted with chitooligosaccharide, 2.5-anhydromannose, and / or low molecular weight chitosan is adjusted to pH 5 to 6 with acetic acid. A method for impregnating or applying wood, characterized by impregnating or applying wood.