JPH06143209A - Manufacture of modified wood - Google Patents

Abstract

PURPOSE:To provide the manufacture of modified wood, in which the flame retardancy of wood is held and dimensional stability is improved. CONSTITUTION:Raw wood is impregnated with two kinds or more of water-soluble compounds, an insoluble incombustible compound as a reaction product is fixed, and the hydroxyl groups of raw wood are crosslinked by a compound having two or more of aldehyde groups. AccordingIy, acquired modified wood is heated in the presence of an acid catalyst in the vapor atmosphere of a formaldehyde derivative and changed into formal, thus obtaining modified wood having excellent flame retardancy and dimensional stability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing modified wood used for housing equipment, building materials and the like.

[0002]

As a method of imparting flame retardancy to wood, for example, as disclosed in JP-A-61-246003, a cation and an anion which react with each other to form an insoluble compound are separately contained. It is known that a natural raw material wood is sequentially impregnated with two kinds of aqueous solutions, and an insoluble non-combustible inorganic compound is generated and fixed to modify the wood. However, although the above method is effective for imparting flame retardancy, it is not effective for imparting dimensional stability. This is because the hydrophilic groups that make up wood exhibit water absorption, and therefore the characteristic of dimensional stability is the anti-swelling ratio (AS).
E) is not improved.

On the other hand, as a method for imparting dimensional stability to wood, formalization treatment is known. The treatment by formalization has been performed for a long time, and is a reaction of crosslinking formaldehyde between hydrophilic hydroxyl groups of wood components (cellulose, hemicellulose, lignin, etc.). By such crosslinking, the hydrophilicity of wood is reduced, and the anti-swelling ratio (ASE) is improved to a value of 50 to 60% at a low weight gain rate of about 5 to 10%. In recent years, as wood has expanded its uses, there has been a demand for modified wood having flame retardancy and improved dimensional stability.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned facts, and an object thereof is to provide modified wood in which flame retardancy of wood is retained and dimensional stability is improved. To provide the manufacturing method of.

[0005]

In the method for producing modified wood according to the present invention, an insoluble incombustible compound, which is a reaction product of two or more water-soluble compounds impregnated in a raw wood, is fixed, and It is characterized in that the modified wood obtained by crosslinking the hydroxyl groups of the raw wood with the compound having an aldehyde group is heated in the vapor atmosphere of the formaldehyde derivative and in the presence of the acid catalyst to be formalized.

[0006]

According to the present invention, since the insoluble incombustible compound is produced and fixed in the raw wood, the insoluble noncombustible compound improves the fire retardancy of the raw wood. further,
Since the compound used in the present invention is a compound having two aldehyde groups, it bridges between the hydrophilic hydroxyl groups of the wood component. If a compound having two or more aldehyde groups is impregnated prior to formalization, the crosslinking of hydrophilic hydroxyl groups of the wood component is increased as compared with the case of only formalization, and the hydrophilic hydroxyl groups of the wood component are increased. The increased cross-linking reduces the hydrophilicity of wood and improves dimensional stability. When the modified wood obtained by fixing the insoluble incombustible compound and crosslinking the compound having two or more aldehyde groups is subjected to formalization treatment, the vapor of the formaldehyde derivative causes the insoluble noncombustible compound and two or more aldehyde groups in the modified wood. Even if a compound having a is present, the modified wood is diffused into the modified wood without being impaired in permeation, subjected to formalization, and excellent in flame retardancy and dimensional stability. On the contrary, if the insoluble incombustible compound is fixed to the wood and the compound having two or more aldehyde groups is cross-linked after the formalization is performed first, the wood is hydrophobized by the formalization, so that it is water-soluble. Impregnation of the compound is hindered, and it is difficult to impart flame retardancy and improve dimensional stability.

The present invention will be described in detail below. In the present invention, formalization is limited to modified wood in which an insoluble incombustible compound is fixed to the raw wood and a compound having two or more aldehyde groups is cross-linked between the hydroxyl groups of the raw wood.

[0008] The shape of the raw material wood is not particularly limited,
For example, log logs, lumber products, sliced veneer, plywood and the like are used. The tree species of the above-mentioned raw material wood is not limited at all.

In the present invention, the production and fixation of the insoluble incombustible compound constituting the modified wood is carried out by impregnating the raw wood with 2
It is realized by simultaneous production of one or more water-soluble compounds. The insoluble non-combustible compound that is fixed in the modified wood is not particularly limited, and examples thereof include borate, phosphate, hydrogen phosphate, carbonate, sulfate, hydrogen sulfate, silicate, and nitrate. , Hydrochloride and the like. In order to fix the above-mentioned insoluble incombustible compound as a reaction product in the raw material wood, two or more kinds of compounds, for example, a cation-containing compound containing a cation species constituting a cation part of the insoluble incombustible compound and an insoluble incombustible compound are used. The raw wood is impregnated with an anion-containing compound containing an anionic species forming the anionic part of the organic compound, and these compounds are reacted with each other in the wood. This insoluble noncombustible compound may be present alone or in combination of two or more in the wood, and is arbitrarily selected according to the desired composition of the insoluble noncombustible compound to be produced in the wood.

Containing the above-mentioned cation-containing compound and anion
A method of impregnating wood with the compound will be described. the above
The cation species of the insoluble incombustible compound is not particularly limited.
However, for example, Mg, Ca, Sr, Ba, etc.
Potassium earth metal ion, Al, Fe, Cu, Co, Ni,
Examples thereof include metal ions such as Mn, Pb and Zn. Also,
The anionic species of the insoluble incombustible compound is not particularly limited.
Not, for example, OH^-, F^-, Cl^-, Br^-，
NO₃ ^-, CO₃ ^2-, BO₃ ^2-, PO_Four ^3-, SO_Four ^2-etc
Is mentioned. One of these cation and anion species
The same kind may be used, or two or more kinds may coexist. Above
As the cation-containing compound that constitutes the on-species, Mg
Cl₂, MgBr₂, MgSO_Four・ H₂O, Mg (NO
₃)₂・ 6H₂O, CaCl₂, CaBr₂, Ca (N
O₃)₂, BaCl₂・ 2H₂O, BaBr₂, Ba
(NO₃)₂, AlCl₃, AlBr₃, Al (S
O_Four)₃, Al (NO₃)₃・ 9H₂O, ZnCl₂etc
And anions containing the above-mentioned anion species are included.
Na as a compound₂CO₃, (NH_Four)₂CO₃, H
₂SO_Four, Na₂SO_Four, (NH_Four)₂SO_Four, H₃P
O_Four, (NH_Four)₂HPO _Four, H₃BO₃, NaB
O₂, NH_FourBO₂But not limited to these
It is not something that can be done. Depending on the type of cation and anion
Constitutes the cation part of the resulting insoluble non-combustible compound
In some cases, it may form an anion part. Up
When selecting cation-containing compounds and anion-containing compounds
Easily produce insoluble and non-combustible compounds in wood
Combinations are preferred.

The method for impregnating the cation-containing compound and the anion-containing compound is not particularly limited.
Examples thereof include a method using an aqueous solution of the compound and a method of spraying a powdery compound. When using an aqueous solution of the compound,
Two kinds of aqueous solutions in which a cation-containing compound and an anion-containing compound are separately contained are used, and both aqueous solutions are sequentially impregnated into a raw material wood by a method such as dipping, impregnation under reduced pressure, and impregnation under pressure. At this time, it is preferable that both aqueous solutions have a temperature of 20 to 80 ° C. in order to accelerate the impregnation into the raw material wood. As an example of the case of spraying the powdery compound, a raw material wood sprayed with the cation-containing compound on one side, and a raw wood wood sprayed with the anion-containing compound on one side, these compounds are sprayed There is a method of directing the surfaces in the same direction and alternately impregnating the raw material wood sprinkled with the cation-containing compound and the raw wood material sprinkled with the anion-containing compound. The wood on which the cation-containing compound and the anion-containing compound are sprayed is heated and cured. This heating method is not particularly limited. The temperature, time, method, etc. of this curing condition are appropriately determined depending on the type and amount of the insoluble noncombustible compound produced. At the time of curing, it is preferable that the solvent in the wood is not volatilized so that the wood is not dried, and examples thereof include a method of sealing a raw material wood with a cation-containing compound and an anion-containing compound sprayed with a sheet. To be

The impregnated amount of the insoluble incombustible compound formed in the modified wood is not particularly limited, but is preferably 20% by weight or more based on the weight of the wood.

As described above, the modified wood used in the present invention is crosslinked between the hydroxyl groups of the raw wood with a compound having two or more aldehyde groups together with the insoluble nonflammable compound. The compound having two or more aldehyde groups cross-links hydroxyl groups longer than formaldehyde and increases cross-linking between hydrophilic hydroxyl groups of the wood component. Therefore, dimensional stability is improved as compared with the case where only formalization is performed. .
The compound having two or more aldehyde groups is realized by impregnating raw wood. The raw material wood may be impregnated with the compound having two or more aldehyde groups alone, or may be mixed with the cation-containing compound or the anion-containing compound for impregnation. Examples of the compound having two or more aldehyde groups include glyoxal, malondialdehyde, succindialdehyde, glutaraldehyde, adipinedialdehyde, maleindialdehyde, phthalaldehyde, isophthalaldehyde, terephthalaldehyde and the like. These compounds are preferably used in a concentration of 1 to 30% by weight.

The modified wood in which the insoluble non-combustible compound is fixed and the compound having two or more aldehyde groups is cross-linked, the wood surface is washed with water if necessary, byproducts and unreacted materials are generated. It is preferable because it is removed.

Next, the modified wood in which the insoluble non-combustible compound is fixed and the hydroxyl groups of the raw wood are cross-linked by the compound having two or more aldehyde groups is added to the modified wood in the vapor atmosphere of the formaldehyde derivative and the acid catalyst. Formalization is carried out by heating in the presence. When the modified wood is subjected to formalization, the vapor of the formaldehyde derivative will not penetrate into the modified wood even if the insoluble incombustible compound and the compound having two or more aldehyde groups are crosslinked in the modified wood. Diffused, formalized, and modified wood with excellent flame retardancy and dimensional stability is obtained. Contrary to the present invention, when the formalization is first performed and then the insoluble incombustible compound is fixed and the compound having two or more aldehyde groups is impregnated, the wood is hydrophobized by the formalization. Therefore, impregnation of two or more kinds of water-soluble compounds that generate insoluble incombustible compounds and compounds having two or more aldehyde groups is inhibited.

The above-mentioned modified wood that undergoes this formalization is
In order to remove excess water, it is preferable to use wood that has been dried and adjusted to a moisture content of 10% by weight or less. This is because if there is excess water, the formaldehyde monomer is easily polymerized by this water to form an oxymethylene chain, and if it becomes an oxymethylene chain, the above-mentioned formalization is diminished and the effect of improving dimensional stability cannot be expected. Is. The method of removing this excess water is air drying, hot air drying, high frequency drying, etc.
There is no particular limitation.

The formaldehyde derivative is a compound which forms a formaldehyde monomer when thermally decomposed, and examples thereof include paraformaldehyde, trioxane and tetraoxane. These are 1 or 2
More than one species can be used. Among these, trioxane and tetraoxane are industrially effective because they are solid and have no formmarin odor, easily sublime, and thermally decompose to form formaldehyde monomer. The formaldehyde derivative is appropriately determined depending on the amount of the acid catalyst and the degree of the formalization reaction, but the formaldehyde derivative is 10 to 300 mol / m ³ in terms of thermal decomposition to formaldehyde monomer. (Capacity of reaction vessel) is appropriate.

The form of vapor permeation of the formaldehyde derivative is not particularly limited. For example, a solid formaldehyde derivative may be volatilized in a reaction vessel to permeate modified wood, or the formaldehyde derivative that has already volatilized may be vaporized. May be introduced into the reaction vessel to penetrate the modified wood.

An acid catalyst is used for the formalization in the present invention. Examples of the acid catalyst include sulfur dioxide, hydrogen chloride, hydrochloride, sulfate, sulfite, boric acid and the like. These can use 1 type (s) or 2 or more types. Among these acid catalysts, particularly when sulfur dioxide is used, hydroxymethylsulfonic acid is generated from formaldehyde and water, which effectively promotes the reaction with wood. The concentration of the acid catalyst is not particularly limited, but usually 1 to 15 mol / m ³ (volume of reaction vessel) is suitable.

It is effective to use a co-catalyst that accelerates the thermal decomposition of formaldehyde derivative into formaldehyde monomer, if necessary, in that the reaction is accelerated.
Examples of the promoter include hydrogen chloride, zinc chloride, chlorides such as iron chloride, sulfates such as iron sulfate, and boric acid and salts thereof. By-products and unreacted substances are produced along with the formation of the insoluble and non-combustible compound in the modified wood. It is also possible not to use the cocatalyst by leaving a part of this by-product or unreacted material. .

The method of permeating the above-mentioned acid catalyst is not particularly limited. For example, when the acid catalyst is a gas, it is introduced into a reaction vessel using a cylinder to permeate the modified wood, and the acid catalyst is liquid or solid. In the case of 1, the modified wood is gasified in the reaction vessel and penetrates the modified wood. When this formalization is carried out under reduced pressure or under pressure, the reaction vessel must have pressure resistance.

Formalization of the modified wood in the present invention is carried out as follows, as an example of using a solid formaldehyde derivative, a gaseous acid catalyst and a solid cocatalyst. First, a predetermined amount of modified wood, in which an insoluble incombustible compound is produced, a formaldehyde derivative, and a co-catalyst are placed in a heated reaction vessel and sealed. Next, the inside of the reaction vessel is depressurized using a vacuum pump. The degree of pressure reduction at this time is preferably 100 mmHg or less. The temperature in the reaction vessel is preferably 90 to 120 ° C. After that, the vacuum pump is stopped, a predetermined amount of a gaseous acid catalyst is introduced into the reaction container, the inside of the reaction container is heated and maintained at a predetermined temperature, and formalization is performed. The acid catalyst may be introduced immediately after the decompression, or after vaporization of the formaldehyde derivative vapor after the decompression. It is preferable to introduce the acid catalyst after the vapor of the formaldehyde derivative is volatilized after the pressure reduction because the discoloration of the wood due to the acid catalyst can be reduced. The temperature of formalization at this time is not particularly limited, but is preferably 90 to 120 ° C. The processing time for formalization is not particularly limited. After performing the formalization, the gas in the reaction vessel is evacuated under reduced pressure while being heated. By sufficiently exhausting this gas, most of the unreacted gas in the wood can be removed. The method of forming formal is not limited to the above.

[0023]

EXAMPLES Examples and comparative examples of the present invention will be given below.

Example 1 As raw material wood, 30 × 60 mm square oak wood was prepared. Using this wood as a cation-containing compound in an aqueous solution of 25% by weight of barium chloride under a reduced pressure of 30 mmHg for 3 hours,
After soaking under a pressure of 3 kg / cm ² for 3 hours, diammonium hydrogen phosphate 40 was added as an anion-containing compound.
30% by weight of an aqueous solution containing 10% by weight of glyoxal as a compound having 2% or more aldehyde groups.
3 hours under reduced pressure of mmHg, 3 hours under pressure of 3 kg / cm ^2.
Soaking was carried out for a period of time to obtain a modified wood in which an insoluble nonflammable compound containing barium phosphate as a component was fixed and a compound having two or more aldehyde groups was crosslinked.

Thereafter, by-products are removed by washing with water,
The modified wood dried at 105 ° C. for 8 hours was placed in a reaction container preheated to 100 ° C., and trioxane as a formaldehyde derivative was further placed in the reaction container at 50 mol / m ³ per volume of the reaction container. .

Next, the vessel was sealed, the pressure was reduced to 50 mmHg by using a vacuum pump and kept for 2 hours to sufficiently volatilize the formaldehyde derivative in the reaction vessel, and then sulfur dioxide (SO ₂ was used as an acid catalyst. 5 mol / m ^{3 was} introduced per volume of the reaction vessel. Then, it hold | maintained at 100 degreeC for 24 hours, and formalized. After the formalization,
The residual gas in the reaction vessel was sufficiently exhausted under reduced pressure to obtain modified wood.

The impregnation rate of the obtained modified wood, the anti-swelling rate (ASE) as the dimensional stability of the modified wood, and the flame retardancy were measured and evaluated.

The impregnation rate was determined according to the following formula. - impregnation rate _{(%) = {(W 2} -W 1) / W 1} ×
100 · W ₁ represents the absolute dry weight of the raw wood. · W ₂ represents the absolute dry weight of the resulting modified wood.

The anti-swelling ratio was determined according to the following formula. - anti-swelling rate _{(%) = {(S 1} -S 2) / S 1}
× 100 · S ₁ represents the swelling ratio of the raw wood. S ₁ is the dimension A of the raw wood after drying, and 72
The dimension B after immersion in time was measured and calculated based on the following formula. _{· S 1 (%) = {} (B-A) / A} × 100 · S 2 represents the swelling rates of the reforming timber. S ₂ is the dimension C of the modified wood after drying, and 72
The dimension D after immersion in time was measured and calculated based on the following formula.・ S ₂ (%) = {(D−C) / C} × 100 Flame retardance was determined by passing a surface burning test for 6 minutes based on JIS-A-1321, and judging whether the flame retardance was 3rd grade. .

The results are shown in Table 1. The flame retardancy was maintained, and the anti-swelling ratio was 70%, which exceeded 60%.

Comparative Example 1 As a raw material wood, a 30 × 60 mm square oak wood was prepared. Using this wood as a cation-containing compound in an aqueous solution of 25% by weight of barium chloride under a reduced pressure of 30 mmHg for 3 hours,
After soaking under a pressure of 3 kg / cm ² for 3 hours, diammonium hydrogen phosphate 40 was added as an anion-containing compound.
3% under a reduced pressure of 30 mmHg for 3 hours in a wt% aqueous solution
Immersion under a pressure of / cm ² for 3 hours gave a wood in which an insoluble incombustible compound was formed and fixed.

Thereafter, by-products are removed by washing with water,
The above wood dried at 105 ° C for 8 hours was
The reaction vessel was heated to 00 ° C., and trioxane as a formaldehyde derivative was placed in the reaction vessel in an amount of 50 mol / m ³ per volume of the reaction vessel.

Next, the vessel was sealed, the pressure was reduced to 50 mmHg by using a vacuum pump, and the vessel was kept for 2 hours to sufficiently volatilize the formaldehyde derivative in the reaction vessel. Then, as an acid catalyst, sulfur dioxide (SO ₂ 5 mol / m ^{3 was} introduced per volume of the reaction vessel. Then, it hold | maintained at 120 degreeC for 16 hours, and formalized. After the formalization,
The residual gas in the reaction vessel was thoroughly exhausted under reduced pressure.

Then, in the same manner as in Example 1, the impregnation rate, anti-swelling rate, and flame retardancy were measured. The results are shown in Table 1. Although the flame retardancy was retained, the anti-swelling ratio was 50%, which did not reach 60%.

Comparative Example 2 As raw material wood, water was previously used as a solvent to make it saturated.
After immersing a 3 mm-thick single plate of Agathis rotary material in an aqueous solution of 80 ° C. in which 3.5 mol of diammonium hydrogen phosphate as an anion-containing compound was dissolved for 2 hours per 1 liter of water, further, per 1 liter of water, It was immersed in an aqueous solution of 2 mol of barium chloride as a cation-containing compound at 80 ° C. for 4 hours to form and fix an insoluble incombustible compound in wood. Then, by-products were removed by washing with water and dried.

Then, in the same manner as in Example 1, the impregnation rate, anti-swelling rate, and flame retardancy were measured. The results are shown in Table 1. Although flame retardancy was retained, the anti-swelling rate was a very low value of 20%.

[0037]

[Table 1]

[0038]

According to the manufacturing method of the present invention, the flame retardancy of wood is maintained and the dimensional stability is improved.

Claims (4)

[Claims] 1. An insoluble incombustible compound, which is a reaction product of two or more water-soluble compounds impregnated in raw wood, is fixed,
Modification characterized by heating modified wood obtained by cross-linking hydroxyl groups of raw wood with a compound having two or more aldehyde groups in a formaldehyde derivative vapor atmosphere and in the presence of an acid catalyst to formmal How to make wood. 2. At least one of glyoxal, malondialdehyde, succindialdehyde, glutaraldehyde, adipinedialdehyde, maleindialdehyde, phthalaldehyde, isophthalaldehyde and terephthalaldehyde as the compound having two or more aldehyde groups. The method for producing a modified wood according to claim 1, wherein at least one seed is used. 3. The method for producing modified wood according to claim 1, wherein at least one of paraformaldehyde, trioxane and tetraoxane is used as the formaldehyde derivative. 4. The modified wood according to claim 1, wherein the acid catalyst is at least one of sulfur dioxide, hydrogen chloride, chloride, sulfate, phosphite and boric acid. Manufacturing method.