JPH01271203A - Manufacture of modified wood - Google Patents

Abstract

PURPOSE:To form an insoluble flame-retardant inorganic substance on a timber surface layer section uniformly and densely by carrying out vacuum impregnating treatment by means of treating liquid to produce the insoluble flame- retardant inorganic substance by mixing, and then immersion under the normal pressure. CONSTITUTION:Wood is fixed in a vacuum container and first treating liquid is injected in the vacuumized and deaerated state into the wood, and vacuum immersing treatment is carried out. Then, the pressure in the container is raised up to the normal pressure, and immersing treatment is carried out in said state. After that, the wood is taken out and immersed in a second treating liquid successively. The wood treatment is carried out by using treating liquid consisting of an inorganic substance producing cations such as barium chloride or the like and an inorganic substance producing anions such as hydrogen phosphase - ammonium or the like, and either of said two is used as the first treating liquid and vacuum impregnating treatment is carried out. Wood of good surface appearance, good surface hardness and good flame-retardant properties can be provided by cleaning and drying the wood after said treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing modified wood used as building materials, and in particular, to a method for modifying thick board materials.

[Conventional technology]

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

In general, modification methods for imparting flame retardancy to wood are broadly classified based on the following flame retardant mechanisms.

(Coating with inorganic substances (6) Promotion of carbonization (C) Inhibition of chain reaction in flaming combustion (d)
Generation of nonflammable gas (e) Heat absorption due to decomposition and release of crystallized water (insulation by foam layer) Here, as explained below, the modification method of adding insoluble nonflammable inorganic substances to wood is in addition to the above ta+. Depending on the type of inorganic material, (b), (c), (d)
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 possibility that it will be dissolved from the wood thereafter, 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 TS.

The carbonization promotion of fb) has the following mechanism. In other words, when wood is heated, it thermally decomposes and generates flammable gas, which causes flaming combustion. At this time, if phosphoric acid or boric acid is present, the thermal decomposition, or carbonization, of the wood is promoted. A carbonized layer is quickly formed. This carbonized layer acts as a heat insulating layer and provides an H flame effect, so if the insoluble nonflammable inorganic substance contains a phosphoric acid component or a boric acid component, 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 (d) 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.
If foreign matter is present in the internal cavity of the wood, the invasion of mycelium will be hindered, and as a result, it will become rotten. It can be anything as long as it does not provide nutrients for fungi.Insect repellent is the same as preservative.

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 filler, the wood itself is less likely to expand or contract, and at the same time, various mechanical strengths, particularly hardness, are improved. Here, as the immobilizing substance, an inorganic substance that is difficult to dissolve in water can be used, so if an insoluble incombustible inorganic substance is immobilized in the wood cell wall, such an effect can be obtained.

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, for example, if an insoluble, nonflammable inorganic substance is directly dispersed in a solvent such as water, and wood is immersed in this dispersion (treatment liquid) to allow the liquid to penetrate into the wood, most of the material that penetrates is water. This results in only solvents such as This is because the narrowest part of the passage through which the treatment liquid permeates into the wood is the pit membrane plan, and the pore diameter here is approximately 0.1 μm. The particle size of the insoluble, nonflammable inorganic particles that are dispersed particles is usually 0.1
This is because it is considerably larger than p1.

Therefore, the inventors have first developed a method that can solve this problem. That is, two types of aqueous solutions (treatment liquids) separately containing cations and anions that react to produce insoluble, nonflammable inorganic substances when mixed are used, and both are sequentially impregnated into raw material wood to form inside the wood. This is a method for producing modified wood by reacting both ions and fixing insoluble, nonflammable inorganic substances (Japanese Patent Application No. 1989-089423, Mei ItBI). In this way, extremely large amounts of insoluble, nonflammable inorganic substances can be efficiently incorporated into the wood.Furthermore, numerous improvements have been made to improve the performance of the -layer and to address new problems. It's here.

[Problem to be solved by the invention]

One such research and development challenge remains: increasing the surface hardness of soft woods such as coniferous trees. - In order to increase the hardness of wood for boat fishing, it is possible to stuff hard substances such as inorganic substances into the voids such as conduits inside the wood and into the cell walls of the wood. Therefore, as mentioned above, by generating and fixing insoluble, nonflammable inorganic substances within wood, the effects of reinforcing wood cells and increasing hardness can be obtained.In particular, in order to increase surface hardness, it is necessary to It is required to selectively generate the same inorganic substance near the surface layer and obtain an inorganic substance distribution that is dense in the surface layer.

Injecting inorganic substances into this surface layer means that if the raw material wood is thick, that is, thick board material (thick board)
This becomes a particularly important issue in this case. However, when impregnation treatment is carried out, which is the conventional practice of first saturating the wood with water and then sequentially immersing the water-saturated wood in the treatment liquid, the treatment liquid becomes It mainly enters the growth rings inside the wood, displacing the water in the wood. As a result, when viewed cross-sectionally, insoluble and nonflammable inorganic substances are produced on average from the surface layer to the deep (center) part of the wood.
It was not possible to obtain the desired surface hardness.

Therefore, in order to selectively generate insoluble, nonflammable inorganic substances on the surface layer of planks, the first treatment liquid was impregnated into the wood using the vacuum impregnation method, which is carried out under reduced pressure, and the second treatment liquid was applied to the wood under normal pressure. A method of impregnation using the immersion method was attempted. According to this method, the intended purpose of concentrating the product on the surface layer of the wood as a whole is achieved, but
On the other hand, there is a problem in that there is uneven impregnation in the surface layer, that is, variations in the thickness of the produced insoluble and nonflammable inorganic layer. Therefore, in areas where insoluble nonflammable inorganic substances are well formed and a thick inorganic layer is formed, the surface hardness improves markedly, but on the other hand, the insoluble inflammable inorganic substances are poorly absorbed (in most cases, the inorganic layer is thick). In the areas where the wood was not formed, there was not much of an increase in hardness, and there was a limit to the improvement of the surface hardness of the wood as a whole.

In view of the above circumstances, this invention selectively generates insoluble, nonflammable inorganic substances on the surface layer of wood, and also aims to make the thickness of the inorganic substance layer uniform, thereby reducing the areas where the hardness increase is small and increasing the overall hardness of the wood. An object of the present invention is to provide a method for efficiently producing modified wood that further increases the surface hardness of the wood and has excellent flame retardancy, rot prevention, insect repellency, and one-dimensional stability.

[Means to solve the problem]

In order to solve the above problems, the present invention impregnates raw material wood to be modified with two or more water-soluble inorganic aqueous solutions (treatment liquids) that produce insoluble non-flammable inorganic substances when mixed. In a method for producing modified wood that generates and fixes the above-mentioned inorganic substances in the wood structure, the wood that has been subjected to the first impregnation treatment by vacuum impregnation is placed in a treatment solution used for the same vacuum impregnation under a specified pressure. After soaking for a certain period of time, the next treatment solution is soaked and impregnated.

[For production]

In this invention, the first treatment liquid (first liquid) is injected into raw material wood in a dry state by a reduced pressure method. In that case,
The ions of the first liquid remain only in the surface layer of the wood and do not penetrate any further into the odor. Then, by immersing the wood after vacuum impregnation in the first liquid for a predetermined period of time under normal pressure,
The first liquid ions enter the entire surface layer evenly and uniformly. When the wood is immersed in the second liquid in this state, the ions of the first liquid in the surface layer that was previously impregnated will try to go out of the wood, and the ions of the second liquid will try to enter the inside of the wood. A reaction occurs at the surface where the ions meet. As a result, insoluble and nonflammable inorganic substances are selectively, evenly and densely formed and fixed on the surface layer of the wood.

〔Example〕

The raw material wood for modification used in this invention is:
There are no particular limitations, such as raw wood logs and sawn timber products.

Examples include sliced veneer and plywood. There are no limitations on these tree species either. The thickness of the wood is also not particularly limited, but for example, if it is a thick board with a thickness of 1 f1 or more, or even 3 cuts or more,
The effects obtained in this invention are more significant.

Insoluble, nonflammable inorganic substances that are generated in wood and dispersed and fixed in the wood tissue are not particularly limited, and include, for example, borates, phosphates, hydrogen phosphates, carbonates, sulfates, and hydrogen sulfate. Salts, silicates, nitrates, fluorides9
Examples include bromides, hydroxides, etc., and two or more types of inorganic substances may coexist in the wood.

Furthermore, one type of insoluble, nonflammable inorganic substance may contain two or more types of cation moieties and/or anion moieties described below.

Elements constituting the cation portion of the above-mentioned inorganic compounds (salts) include alkali metals such as Na, Mg, and C.
a, alkaline earth metals such as Sr, Ba, Zn and AI
Although it is preferable to use transition elements such as Mn, Ni, and Cd, and Si
, carbon group elements such as Pb, etc. may also be used.

BO constitutes the anion portion.

, PO4, GO= , 504 and OH anions are preferably used. In Bow, PO, Anion,
Since the effect of the flame retardant mechanism (b) can be obtained, and the effect of the same (d) can be obtained with CO and anion, the − layer is preferable. However, it is not limited to these, for example, F, CI, Br, O.

Halogens, which may be N Os , S i Oa I S i Os anions, etc., have the advantage that the effects of C1 and (d) can be expected at the same time.

The cation portion and the anion portion may be used alone or in combination, but not all combinations are possible, and the ionic radius, etc. There are restrictions due to In view of such conditions, both are arbitrarily selected and the water-soluble inorganic substances containing them are dissolved in water to prepare the cation-containing treatment liquid and the anion-containing treatment liquid.

In addition, the above-mentioned halogens and OH anions can be used alone or included together in a cation-containing treatment liquid and/or an anion-containing treatment liquid containing other anions to produce apatite etc. in the wood. It may be prepared as follows.

Inorganic substances that dissolve in water to produce the above cations include MgC1x, MgBrt, Mg5Oa .H
z O,Mg (NOx)* ・6Hs O,CaC
1m, CaBrl, Ca (Now)
t, Ba Clx・2Ht O, BaBr5, Ba
(NOx)z, AlC15, AlBr5, Al
z (SOa)s, AI(Not)s ・9H
Examples include IO, ZnCIt, etc.
Examples of inorganic substances that produce the above anions when dissolved in water include, but are not limited to, Nag Cot
, (NH4)t COs , HI SO4, Nag
304, (NH4)zSO4,HsPO4,
Nag HPO4, (NH4)* HPO4, Hs B
Examples include O-, Na Bog, NH4B Oz, etc., but are not limited thereto.

Wood is processed in the following manner using such a cation/anion-containing image processing solution.

First, one of the cation-containing treatment liquid and anion-containing treatment liquid is used as a first liquid and is impregnated into wood by a reduced pressure method.

Conventionally, prior to impregnation with the first liquid, the raw material wood was left in water for a long time to undergo water saturation treatment, but in the present invention, such pretreatment can be omitted. This is because in vacuum impregnation, the pressure is reduced in the voids inside the wood, and the treatment liquid is injected into the low-pressure areas, so there are voids within the wood that can create a low pressure. This is because it is preferable that it be dry to some extent. Here, the degree of drying does not need to be particularly bone dry, but the fiber saturated moisture content (
30%) or under normal air-dry conditions may be used as is.

This reduced pressure impregnation is performed, for example, by the following operation. First, the raw wood is fixed in a vacuum container and the pressure is reduced.
Once the pressure has been reduced to a predetermined level, this pressure is maintained for about 1 to 2 hours to reduce the pressure inside the wood. Thereafter, a treatment liquid is introduced into the container, and once the wood is completely immersed in the liquid, the pressure is returned to normal. Alternatively, as another method, first introduce the treatment liquid into the container and soak the wood, then reduce the pressure from that state and once the predetermined pressure is obtained,
It may be maintained for about 2 hours and then released to atmospheric pressure. The reduced pressure state is not particularly limited, but is preferably about 50 U+Hg or less in order to efficiently perform sufficient impregnation.

Next, after the above-mentioned reduced pressure impregnation treatment, the wood is immersed in the first liquid for a predetermined period of time under normal pressure (.

The immersion time at this time is preferably set appropriately depending on various conditions such as the type of wood, the thickness of the wood, and the composition and concentration of the treatment liquid, and is not particularly limited. To give an example as a guideline, for example, if the wood has a thickness of about 15 cranes, it is preferable to soak it for about 30 minutes or more, more preferably about 1 hour or more.

Thereafter, immersion impregnation is carried out under normal pressure using a second solution containing ions that react with the ions of the first solution to form an insoluble, nonflammable inorganic substance.

In this way, the impregnation process is carried out inside the wood, especially the surface layer (
For example, insoluble, nonflammable inorganic substances are formed densely and evenly within a range of 1 to 2 mm from the surface of the thick plate. After that, modified wood is obtained by drying, but before that, for the reasons described below, leaching treatment is performed to remove soluble unreacted ions and byproducts. Alternatively, insoluble and nonflammable inorganic substances generated on the surface of the wood may be removed by washing with water or the like.

The above-mentioned soluble components left in the wood absorb a large amount of water and moisture, and depending on the type, may exhibit deliquescent properties, so if too much of these components remain, the wood absorbs water and moisture.
The moisture absorption becomes too high. This may make the wood unsuitable for use as a building material, so these can be appropriately removed through leaching treatment to improve the water resistance and weather resistance of the wood. This leaching treatment is carried out by providing a post-treatment bath and immersing the material in water for a long time, or leaving it in running water for washing. However, depending on the type of soluble components, there are many components that are nonflammable and can contribute not only to flame retardation of wood but also to mechanical reinforcement, dimensional stabilization, etc. One way to improve the performance of the wood is to leave some of them in place.

Regarding the appearance of modified wood, that is, its wood texture, when it is dried after treatment9, insoluble and nonflammable inorganic substances formed on the surface of the wood precipitate white, making the entire wood look powdery. Since there is a risk that the wood will get dirty and the appearance will be damaged, it is also effective to wash the treated wood to maintain its appearance.

It goes without saying that the manufacturing method according to the present invention is not limited to the above embodiment. For example, not only the two liquids but also a third liquid, a fourth liquid, etc. may be prepared and impregnated repeatedly by any method. The cation- and anion-containing side treatment liquids used at this time may be of the same type or different types,
Further, if necessary, 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 - A 15-thick piece of solid Douglas fir was fixed in a vacuum container and degassed with a vacuum pump until the pressure inside the container was 40 Torr.
After the temperature became below r, degassing was continued for another 2 hours. Next, while maintaining this reduced pressure state, a barium chloride aqueous solution (BaC11211□0° concentration 2 mol/water 1
6. Temperature: 60° C., pH: 5-6). After the injection of the first liquid was completed, the pressure inside the container was returned to normal pressure, and the wood was left immersed in the first liquid for one hour. After that, the wood was taken out, followed by a second solution of diammonium hydrogen phosphate aqueous solution [(N)l, ), HPO, concentration 3.5 mol.
/ water IJ, temperature 60°C, pH 5-6] for 24 hours.

The wood after the impregnation treatment was immersed in water for 24 hours to perform a solute treatment, and then dried to obtain a modified wood.

Examples 2 to 5 and Comparative Examples 1 to 3 - In the same manner as in Example 1 above, impregnation operations were performed under the conditions shown in Table 1 to obtain modified wood.

However, in the comparative example, after being impregnated with the first liquid under reduced pressure, the wood was immediately pulled up without being immersed in the first liquid under normal pressure and left standing.

The impregnation rate of insoluble, nonflammable inorganic substances and surface hardness of the obtained modified wood were investigated. The impregnation rate of the inorganic substance is the weight ratio of the insoluble, nonflammable inorganic substance to the weight of bone-dry wood, and the surface hardness was measured using a Percoll hardness meter, and the scale was read and compared. Note that the hardness of the untreated raw material wood is O.

The above results are shown in Table 1.

As shown in Table 1, the modified wood of the example, which was soaked for 1' to 2 hours after being impregnated with the first liquid under reduced pressure, showed no significant difference in the impregnation rate of insoluble and nonflammable inorganic substances compared to that of the comparative example. Even without,
A high degree of surface hardness is achieved because they are concentrated in the surface layer of the wood (within a range of about 1 to 2 fi from the surface) and are distributed to form a uniform insoluble, noncombustible inorganic layer.

〔Effect of the invention〕

According to the method for producing modified wood according to the present invention, it is possible to selectively, uniformly, and densely generate insoluble incombustible inorganic substances on the surface layer of the wood, thereby further improving the surface hardness of the modified wood. becomes possible. At the same time, modified wood with excellent properties such as flame retardancy, rot/insect repellency, dimensional stability, and mechanical strength can be efficiently obtained.

Agent: Patent Attorney Takehiko Matsumoto

Claims (1)

[Claims] 1 The raw material wood to be modified is individually impregnated with two or more water-soluble inorganic aqueous solutions (treatment liquids) that produce insoluble, non-flammable inorganic substances when mixed to generate and fix the inorganic substances in the wood structure. This is a method for producing modified wood, in which the wood that has been subjected to the first impregnation treatment by vacuum impregnation is immersed in the treatment solution used for the same vacuum impregnation for a predetermined period of time under normal pressure, and then the next process is carried out. A method for producing modified wood, characterized by impregnating it with a treatment solution.