JPH02116509A - Manufacture of modified lumber - Google Patents

Abstract

PURPOSE:To manufacture efficiently modified lumber which is provided with more high combustibility and superior in wood preserving properties, dimensional stability and dynamic strength also, by a method wherein at least a magnesium hydrogenphosphate hydrate is generated/fixed as an insoluble and noncombustible inorganic matter. CONSTITUTION:The title method is constituted so that at least magnesium hydrogenphosphate hydrate is generated/fixed as an insoluble and noncombustible inorganic matter, in a modified lumber manufacturing method wherein a water-insoluble and noncombustible inorganic matter is generated/fixed within a lumber structure by infiltrating individually at least two kinds of aqueous solutions of water-soluble inorganic matters, which cause to generate the insoluble and noncombustible inorganic matter by mixing up with each other, into raw material lumber, which is going to modify. Since the magnesium hydrogenphosphate hydrate is fixed within the lumber, there noncombustible effects such as a coating, acceleration in carbonization and heat absorption/cooling are obtained respectively due to the inorganic matter, a phosphoric acid ion and discharge of water of crystallization and more high noncombustibility can be imparted to the lumber. Since the same magnesium hydrogenphosphate hydrate is of a stabilized insoluble hydrate, water resistance of an obtained modified lumber can be improved.

Description

[Detailed Description of the Invention] C. Industrial Application Field] This invention relates to a method for producing modified wood used as housing equipment, building materials, etc.

[Conventional technology]

As a method for modifying wood, research has been conducted on methods to impart properties such as HH (fire retardant) 1 dimensional stability, rot and insect repellency, mechanical strength 2 surface hardness, etc. by producing insoluble and nonflammable inorganic substances in wood. being developed.

In general, methods for modifying wood to impart flame retardancy to it are broadly classified based on the mechanism of flame retardancy as follows.

(al Coating with inorganic substances (bl Carbonization promotion (C) Inhibition of chain reaction in flaming combustion (dl
Generation of non-flammable gas (e) Heat absorption due to decomposition and release of crystallized water (fl) Insulation by foam layer Here, the modification method of incorporating insoluble non-flammable inorganic substances into wood is as explained below. However, depending on the type of inorganic material, (bl, (cl, (di
This is an excellent method that can also be expected to have effects such as Moreover, once this insoluble, nonflammable inorganic substance is fixed in the wood structure, there is little risk of melt coming out of the wood, so there is little worry that its effects will diminish.

In the above, (a) coating with an inorganic substance means that even if the material is flammable, it can be made flame retardant by combining it with a non-flammable inorganic substance at an appropriate blending ratio. For example, the conventionally known wood chip cement board is made by mixing combustible wood with non-combustible cement at a weight ratio of about 1:1 and forming it into a board shape.
Recognized as a quasi-noncombustible material by IS.

(The mechanism behind carbonization promotion of BL is as follows. In other words, when wood is heated, it thermally decomposes and generates flammable gas, which flames and burns. At this time, phosphoric acid Alternatively, the presence of boric acid promotes thermal decomposition, or carbonization, of wood, and a carbonized layer is quickly formed.This carbonized layer acts as a heat insulating layer and provides a flame retardant effect, so that the insoluble and nonflammable inorganic substances If an acid component or a boric acid component is included, the flame retardant effect of this modified wood will be even higher.

The inhibition of the chain reaction in flaming combustion (C) is contributed by halogen, and as a result of the halogen acting as a chain transfer agent in the radical oxidation reaction in the flame, the oxidation reaction is inhibited. This is the mechanism by which the flame retardant effect occurs. Therefore, if the insoluble nonflammable inorganic substance contains a halogen, these effects can also be obtained.

Finally, the generation of nonflammable gas (di) will be explained.

This is because compounds such as carbonates and ammonium salts generate nonflammable gases such as carbon dioxide, sulfur dioxide, and hydrogen halides through thermal decomposition, but these gases dilute flammable gases and prevent combustion. It is. Therefore, if the insoluble nonflammable inorganic substance contains something that can generate the above-mentioned nonflammable gases, such as carbonate, a flame retardant effect due to this mechanism can also be obtained.

Next, the antiseptic and insect repellent effects of wood containing this insoluble, noncombustible inorganic substance will be explained. When fungi cause wood to rot, mycelium first invades the inner cavity of the wood.
The presence of foreign matter in the internal cavity of the wood prevents mycelium from entering the wood, and as a result, the wood becomes less susceptible to decay. The foreign matter in the wood lumen does not have to be a particularly antiseptic agent (preservative), and may be anything as long as it does not provide nutrients for fungi. The same applies to insect prevention as to preservatives.

However, it is acceptable for foreign substances to have a medicinal effect; for example, it is preferable to use substances that are poorly digestible or indigestible to insects, or substances that have a repellent effect. Therefore, if an insoluble, nonflammable inorganic substance is included in the inner cavity of wood, it is effective for preventing wood from rotting and insects.

Furthermore, regarding the dimensional stability and mechanical strength of wood, for example, if wood is swollen with water and some substance can be fixed in the wood cell walls in that state, both of the above properties will be improved due to the bulk effect. In other words, if the inside of the wood cell wall is occupied by the filling material, the wood itself is less likely to expand or contract (and at the same time, various mechanical strengths are improved.Here, water is used as the fixing substance). Since inorganic substances that are difficult to dissolve in wood can also be used, these effects can be obtained by fixing insoluble, nonflammable inorganic substances in the wood cell walls.

Finally, regarding the hardness (surface hardness) of wood, in general,
In order to increase the hardness of wood, it is sufficient to stuff hard substances such as inorganic substances into the voids such as the four pipes inside the wood and into the cell walls of the wood. The effects of reinforcement and increased hardness can be obtained. Here, it is more effective if the inorganic substances are generated intensively on the surface layer of the wood.

As described above, the method of incorporating insoluble, nonflammable inorganic substances is very effective in modifying wood, including flame retardation, but it has the following problems.

Generally, if you try to disperse an insoluble, nonflammable inorganic substance in a solvent such as water and immerse the wood in this dispersion (treatment liquid) so that the liquid penetrates into the wood, most of the material that saps is water. This results in only solvents such as This is because the treatment liquid permeates into the wood (the narrowest part of the passage through which it must pass is the pit membrane run, where the pore diameter is approximately 0.1 μl). The particle size of the insoluble, nonflammable inorganic material that is the dispersed particle is usually 0.
This is because it is considerably larger than 1μ.

Therefore, the inventors have first developed a method that can solve this problem. That is, two types of aqueous solutions containing separately cations and anions (referred to as "cation-containing treatment liquid" and "anion-containing treatment liquid" in this order) that react to produce an insoluble nonflammable inorganic substance when mixed are prepared. , a method for manufacturing modified wood in which raw material wood is impregnated with both ions in order to cause both ions to react inside the wood, thereby fixing the insoluble and nonflammable inorganic substance (Japanese Patent Application Laid-Open No. 61-246003)
In this way, an extremely large amount of insoluble and nonflammable inorganic substances can be efficiently incorporated into the wood.

[Problem to be solved by the invention]

According to the above manufacturing method, it is possible to obtain modified wood that is excellent in flame retardancy, rot prevention, insect repellency, dimensional stability, and mechanical strength. In recent years, higher standards have been required, and the current situation is that we are unable to fully meet these demands. That is,
Conventional modified wood was mainly aimed at achieving the above-mentioned flame retardant mechanisms (a) to (d) brought about by impregnated inorganic substances, but the flame retardant effect obtained by this method has reached its limit. There is.

In view of these circumstances, this invention provides a high degree of flame retardancy by adding and combining flame retardant effects based on a new mechanism, and also has excellent antiseptic and insect repellent properties, dimensional stability, mechanical strength, etc. Our objective is to provide a method for efficiently producing superior modified wood.

[Means to solve the problem]

In order to solve the above problem, the inventors discovered that if an insoluble nonflammable inorganic substance could be fixed as a hydrate, the effect of the flame retardant mechanism (e) (=endotherm due to release of crystal water) could be obtained. After repeated studies focusing on this, we finally completed this invention.

Therefore, this invention involves impregnating raw material wood to be modified with an aqueous solution of two or more types of water-soluble inorganic substances that produce insoluble non-flammable inorganic substances by mixing them together, and injecting the same insoluble non-flammable inorganic substances into the wood structure. A method for producing modified wood in which at least magnesium hydrogen phosphate hydrate is produced and fixed as the insoluble, nonflammable inorganic substance.

At least one of the two or more water-soluble inorganic aqueous solutions contains at least a water-soluble magnesium salt, and at least one of the two or more water-soluble inorganic aqueous solutions contains at least an alkali hydrogen phosphate. Metal salts and/or
Or it is preferable that it contains an ammonium hydrogen phosphate salt.

[For production]

In this invention, since magnesium hydrogen phosphate hydrate is fixed in the wood, the following are mainly used: Coating with inorganic substances (flame retardant mechanism (a) above) Carbonization promotion with phosphate ions (= same (b))・The three flame retardant effects of heat absorption and cooling (=(e)) due to the release of crystallized water can be obtained, and even higher flame retardance can be imparted to wood. Moreover, since the magnesium hydrogen phosphate hydrate is a stable and insoluble hydrate, it is possible to improve the water resistance of the obtained modified wood. Furthermore, since magnesium hydrogen phosphate hydrate is easy to produce, it is advantageous in terms of production efficiency.

〔Example〕

The present invention will be explained in detail below.

The raw material wood for modification used in this invention is not particularly limited, and examples include raw wood logs, sawn timber products, sliced veneer 2 plywood, and the like. There are no restrictions on the species of these trees.

In this invention, magnesium hydrogen phosphate (MgHPO) hydrate (trihydrate, superhydrate, etc.) is selected as the insoluble, nonflammable inorganic substance that is generated in the raw material wood and dispersed and fixed in the wood structure. but is not limited to, any other insoluble, nonflammable inorganic substances (e.g., borates, phosphates, hydrogen phosphates other than those listed above, carbonates,
Sulfates.

One or more of hydrogen sulfates, silicates, nitrates, hydroxides, etc.) may also be generated and fixed. Further, the above-mentioned arbitrary insoluble nonflammable inorganic substance may be constituted by, for example, two or more types of cation and/or anion moieties illustrated below, and is not limited in any way.

The cation part of magnesium hydrogen phosphate hydrate is M g
*-, the anion moiety is HP O,'-, and the former is, for example, M g CI t , M g (N
O)s.

It is obtained by dissolving a water-soluble magnesium salt such as M g S ()4 in water, the latter being for example Kg HP 04
.

Nag HPO4, (NH4)! It can be obtained by dissolving an alkali metal hydrogen phosphate salt such as HPO4 and/or an ammonium hydrogen phosphate salt in water.

In addition, examples of the elements of the cation portion of the insoluble nonflammable inorganic material other than the above-mentioned magnesium hydrogen phosphate hydrate include alkali metals such as Na, Mg, and Ca.

Alkaline earth metals such as Sr and Ba, Mn, and Ni.

Transition elements such as Zn and Cd, carbon group elements such as St and Pb,
A1 etc. can be preferably used. Among these, alkaline earth metals (Mg, Ca, Ba), Zn, and AI are mentioned as particularly preferable examples. these are,
For example, the water-soluble Mg salts mentioned above, CaClt, Ca
Brt , Ca (NOl)t l BaC1g
'2Hz o, BaBrz, Ba (Not)x,
AICII, AlBr5, A11(SO4)s,
It is obtained by dissolving A I (NOs)s .9H,0, ZnCL, etc. in water.

The anion of the above-mentioned arbitrary insoluble nonflammable inorganic substance is B
og, PO,, Cow, SO4 and OH anions are given as examples. Especially B.O.

For anions, the above flame retardant mechanism (bl, (el
(HlBO, water release due to decomposition) effect, PO4
It is more preferable to obtain the same effect (b) for anion and the same effect (dl) for COl. However, the present invention is not limited to these, and O, NOl, SiO4°
It may be s, F, C1, Br anion, etc.

These anions are N a t COx + (NH4
) i Cot , Hz SO4, Nag SOa.

(NH4) = SO4, Hs PO4, Nam HPO
−.

(NH4)l HPO4, Hs BOs, NaBog
.

Obtained by dissolving NH4BO, etc. in water.

The above-mentioned water-soluble inorganic substances are arbitrarily selected according to the composition of the desired insoluble non-flammable inorganic substance to be produced in the wood, and by melting them separately in water, cation-containing substances containing the desired cations can be obtained. A processing liquid and an anion-containing processing liquid containing desired anions are prepared. however,
The treatment liquid containing at least one cation has at least M
The treatment solution containing at least one g cation and anion must contain at least HPO and an anion. Note that a plurality of types of water-soluble inorganic substances may be dissolved in one treatment liquid as long as a uniform aqueous solution can be formed without reacting with each other. Furthermore, the treatment liquid may be prepared so as to produce apatite or the like in the wood.

The wood is treated by sequentially impregnating it with the above-mentioned cation/anion-containing image processing solutions. For example, first, one of the image processing liquids (the first liquid) is impregnated into the wood by immersing the raw material wood in the same processing liquid.

At this time, prior to impregnation, it is preferable to subject the raw material wood to a water saturation treatment so that the wood is sufficiently saturated with water. This is because the ions in the first liquid can diffuse quickly using the water in the wood as a medium, reducing the impregnation treatment time. , steaming, impregnation under reduced pressure, impregnation under pressure, etc.

Next, the wood is impregnated with a treatment liquid (second liquid) containing ions that react with the first liquid to generate insoluble nonflammable inorganic substances, thereby generating the same insoluble nonflammable inorganic substances inside the wood.

After that, if necessary, add a third liquid, a fourth liquid...
etc. may be prepared and impregnated repeatedly to densify the product layer. The cation/anion-containing image processing liquids used at this time may be of the same type or different types. Further, the method of impregnating the first liquid, the second liquid, etc. is not particularly limited, and for example, impregnation can be carried out under reduced pressure. Note that when the first liquid is impregnated under reduced pressure, the above-mentioned water saturation treatment of the raw material wood is not necessary.

After the insoluble, nonflammable inorganic substance containing at least magnesium hydrogen phosphate hydrate is generated and fixed in the wood as described above, the surface of the wood is washed with water or subjected to leaching treatment, etc., as necessary, and then dried. , modified wood is obtained.

It goes without saying that the method for producing modified wood according to the present invention is not limited to the above embodiment. For example, curing may be performed after the impregnation treatment to promote the reaction for producing insoluble and nonflammable inorganic substances.

Next, more detailed examples of the present invention will be described together with comparative examples.

Example 1 - 3mm corotary veneer of agathis wood immersed in water,
A saturation treatment was performed under reduced pressure of about 0++n) Ig to sufficiently impregnate the inside of the wood with water.

The obtained saturated veneer was treated with an aqueous magnesium chloride solution (4,0
n+ol/C60°C) for 24 hours.

Next, this veneer was soaked in an aqueous diammonium hydrogen phosphate solution (
4.0 mol/C60°C) for 24 hours to generate an insoluble, nonflammable inorganic substance (-magnesium hydrogen phosphate hydrate) within the wood. After washing the obtained treated veneer with water,
It was dried at 110° C. for 6 hours to obtain modified wood.

Examples 2 to 5 and Comparative Examples 1 and 2-Similar to the above examples, the first liquid and the second liquid shown in Table 1 were
By impregnating the wood with the liquid, modified wood to which magnesium hydrogen phosphate hydrate was fixed was obtained.

The impregnation rate of magnesium hydrogen phosphate hydrate (trihydrate and heptahydrate) (=weight ratio to 100 wood weight) and flame retardance of the above-obtained modified wood were investigated. Regarding flame retardancy, a surface test was conducted in accordance with JIS A 1321, and the heat value 1 smoke emission coefficient and afterflame were both flame retardant 3.
I was able to indicate whether the item met the grade standards (○) or not (x).

In other words, the calorific value tdθ is 350°C/min or less1
If the smoke coefficient is CA20Cs-m" or less and the afterflame is 30 seconds or less, it is marked as ○, and if it exceeds these standards even slightly, it is marked as ×.Also, all three items above meet the above criteria. A comprehensive evaluation of flame retardancy was performed, with ○ being given as ○ if it met the criteria, and × being given as × when there was even one item that did not meet the standards.

The results are also shown in Table 1.

As shown in Table 1, the modified wood of the example on which magnesium hydrogen phosphate hydrate was fixed has higher flame retardancy with lower calorific value than the modified wood of the comparative example. It turned out that

〔Effect of the invention〕

According to the method for producing modified wood according to the present invention, by fixing at least magnesium hydrogen phosphate hydrate, it is possible to efficiently obtain modified wood with higher flame retardancy than conventional methods. .

At the same time, this modified wood has antiseptic and insect repellent properties and mechanical strength of 1
It has excellent dimensional stability and appearance, and has advanced performance that makes it ideal as a building material.

Agent: Patent Attorney Takehiko Matsumoto

Claims (1)

[Scope of Claims] 1. Raw material wood to be modified is individually impregnated with an aqueous solution of two or more water-soluble inorganic substances that produce insoluble non-flammable inorganic substances when mixed, so that the same insoluble non-flammable inorganic substances are produced within the wood structure. A method for producing modified wood that produces and fixes an inorganic substance, the method comprising producing and fixing at least magnesium hydrogen phosphate hydrate as the insoluble, nonflammable inorganic substance. 2. At least one of the two or more water-soluble inorganic aqueous solutions contains at least a water-soluble magnesium salt, and at least one of the water-soluble inorganic aqueous solutions contains at least an alkali metal hydrogen phosphate salt. and/
The method for producing a modified wood according to claim 1, wherein the modified wood contains an ammonium hydrogen phosphate salt.