JPH06143207A - Manufacture of modified wood - Google Patents

Abstract

PURPOSE:To improve the flame retardancy and dimensional stability of wood by heating modified wood, to which an insoluble incombustible compound as the reaction product of two kinds or more of water-soluble compounds impregnated to raw wood is fixed, in the presence of an acid catalyst in the vapor atmosphere of a formaldehyde derivative and changing modified wood into formal. CONSTITUTION:When an insoluble incombustible compound is formed and fixed in raw wood and raw wood is given flame retardancy and the modified wood is acetalized in the presence of an acid catalyst, the vapor of a formaldehyde derivative is diffused into modified wood without the inhibition of permeation even when there is the insoluble incombustible compound in modified wood, thus obtaining modified wood having excellent flame retardancy and dimensional stability. When acetalization is conducted prior to the formation and fixing of the insoluble incombustible compound, on the contrary, a change into a hydrophobic state of wood progresses by acetalization, thus impeding the impregnation of two kinds or more of water-soluble compounds forming the insoluble incombustible compound, then resulting in the difficult impartment of flame retardancy.

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. It exhibits water absorption due to the hydrophilic groups that make up wood, and therefore has a low level of swelling resistance (ASE), which is a characteristic of dimensional stability.

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, modified wood having both good flame retardancy and dimensional stability has been demanded.

[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 a method for producing a modified wood having excellent flame retardancy and dimensional stability of wood. To do.

[0005]

The method for producing modified wood according to the present invention is a method for producing a modified wood in which a raw wood is impregnated with an insoluble incombustible compound, which is a reaction product of two or more water-soluble compounds, It is characterized in that it is heated in the vapor atmosphere of the derivative and in the presence of an acid catalyst to form a formal.

[0006]

According to the present invention, since the insoluble and incombustible compound is formed and fixed in the raw wood, the raw wood is provided with flammability. When this flame-retarded modified wood is subjected to formalization, the formaldehyde derivative vapor diffuses into the modified wood without impeding the permeation even if an insoluble incombustible compound is present in the modified wood. , Formalized, and modified wood with excellent flame retardancy and dimensional stability can be obtained. On the contrary, when the insoluble incombustible compound is formed and fixed after the formalization is performed first, the wood becomes hydrophobic due to the formalization, so that the impregnation of two or more water-soluble compounds that form the insoluble incombustible compound It is difficult to impart flame retardancy.

The present invention will be described in detail below. In the present invention, the formalization is applied to the modified wood in which the insoluble incombustible compound is formed and fixed in the raw wood.

The shape of the above-mentioned raw material wood used in the present invention is not particularly limited, and 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 modified wood which is provided with flame retardancy by fixing the insoluble incombustible compound as the reaction product is used. The insoluble non-combustible compound that is fixed in the modified wood is not particularly limited, for example, borate,
Examples thereof include phosphates, hydrogen phosphates, carbonates, sulfates, hydrogen sulfates, silicates, nitrates and hydroxides. In order to fix the insoluble incombustible compound as a reaction product in the raw wood, a cation-containing compound containing a cation species forming the cation part of the insoluble incombustible compound and an anion part of the insoluble incombustible compound are formed. When an anion-containing compound containing an anionic species is impregnated into a raw material wood and these compounds are reacted with each other in the wood, an insoluble non-combustible compound is produced. 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 not particularly limited, and may be appropriately determined depending on the type and amount of the insoluble incombustible compound to be produced. During the above curing, it is preferable that the solvent in the wood is not volatilized and the wood is not dried. This method is not particularly limited, and examples thereof include a method of sealing a raw material wood on which a cation-containing compound and an anion-containing compound are dispersed with a sheet.

The modified wood on which the above-mentioned insoluble incombustible compound has been produced and fixed is preferably washed with water on the surface of the wood, as the by-products and unreacted materials are removed.

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

Next, the denatured wood on which the insoluble incombustible compound is fixed is heated in the vapor atmosphere of the formaldehyde derivative and in the presence of an acid catalyst to be formalized. This formalization imparts dimensional stability to the modified wood. Contrary to the present invention, when the insoluble incombustible compound is produced and fixed by performing the formalization first, the impregnation of the compound is alienated because the hydrophobization of wood proceeds due to the formalization, whereas the formal of the present invention is excluded. If an insoluble incombustible compound is generated and fixed prior to conversion, the vapor of the formaldehyde derivative is likely to diffuse into the modified wood, so that both flame retardancy and dimensional stability can be imparted.

The above modified wood that undergoes this formalization is
In order to remove excess water, it is preferable to dry and adjust the moisture content to 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 not particularly limited, and may be air drying, hot air drying, high frequency drying, or the like.

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, and for example, a solid formaldehyde derivative may be volatilized in the reaction vessel to permeate the modified wood, or the already vaporized formaldehyde derivative may be permeated. 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.

A co-catalyst that accelerates the thermal decomposition of the formaldehyde derivative into formaldehyde monomer is used if necessary. 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. These co-catalysts may be made to use without co-catalyst by leaving a part of by-products and unreacted substances generated by the formation of the insoluble non-combustible compound in the modified wood.

The method of permeating the above 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 pressure reduction or after the formaldehyde derivative is volatilized after the pressure reduction. It is preferable to volatilize the formaldehyde derivative after depressurization and then introduce the acid catalyst because the discoloration of 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 formalization for a predetermined time, the gas in the reaction vessel is evacuated while heating.
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.

[0022]

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

Example 1 As raw material wood, water was previously used as a solvent to make it saturate,
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 obtain a modified wood in which an insoluble incombustible compound containing barium phosphate was produced and fixed.

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. Further, trioxane as a formaldehyde derivative was placed in the reaction container at 50 mol / m ³ per reaction container volume, As a co-catalyst, ferric sulfate 0.17 kg / m ^{3 was} added.

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

Example 2 As raw material wood, water was previously used as a solvent to make it saturate,
A 3 mm thick lauan veneer was dipped 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, and then a cation was added per 1 liter of water. It was immersed in an aqueous solution of 2 mol of barium chloride as a contained compound at 80 ° C. for 4 hours to obtain a modified wood in which an insoluble noncombustible compound containing barium phosphate was formed and fixed.

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 120 ° C. Further, trioxane as a formaldehyde derivative was placed in the reaction container at 50 mol / m ³ per volume of the reaction container. .

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

Example 3 As raw material wood, water was previously used as a solvent to make it saturate.
A plurality of 1 mm lauan veneers (1) and (2) were prepared.

On the upper surface of the single plate (1), diammonium hydrogen phosphate as a compound containing anions 340 in a powder state is used.
In addition to being uniformly sprayed at a rate of g / m ² , barium chloride as a cation-containing compound was uniformly sprayed on the upper surface of the single plate (2) at a rate of 470 g / m ^{2 in} a powder state. These veneers were alternately laminated in the order of (1), (2), (1) ... With the compound-dispersed surface facing upward. The obtained veneer laminate was sealed and cured at 80 ° C. for 24 hours to obtain a modified wood in which an insoluble nonflammable compound containing barium phosphate was produced and fixed.

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 using a vacuum pump, and the vessel was kept for 2 hours to sufficiently volatilize the formaldehyde derivative in the reaction vessel. Then, sulfur dioxide (SO ₂ was used as an acid catalyst). 5 mol / m ^{3 are} introduced per reaction vessel volume. Then, it hold | maintained at 100 degreeC for 16 hours, and formalized. After the formalization,
The residual gas in the reaction vessel was sufficiently exhausted under reduced pressure to obtain modified wood.

Example 4 As raw material wood, water was previously used as a solvent to make it saturate.
A plurality of 1 mm lauan veneers (1) and (2) were prepared.

On the upper surface of the veneer (1), 510 g / m ^{2 of} aluminum sulfate in the form of powder as an anion-containing compound.
In addition to being evenly sprayed at a ratio of, the powder mixed with 300 g of barium chloride and 400 g of barium hydroxide as a cation-containing compound on the upper surface of the single plate (2) is 700
It was sprayed uniformly at a rate of g / m ² . (1), (2), (1).
The layers were alternately laminated in the order of. The obtained veneer laminate was sealed and cured at 80 ° C. for 24 hours to obtain a modified wood in which an insoluble incombustible compound containing barium sulfate as a component was produced and fixed.

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 120 ° C. Further, trioxane as a formaldehyde derivative was 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 using a vacuum pump, and the vessel was kept for 2 hours to sufficiently volatilize the formaldehyde derivative in the reaction vessel. Then, sulfur dioxide (SO ₂ was used as an acid catalyst). 5 mol / m ^{3 are} introduced per reaction vessel volume. Then, it hold | maintained at 120 degreeC for 16 hours, and formalized. After the formalization,
The residual gas in the reaction vessel was sufficiently exhausted under reduced pressure to obtain modified wood.

Example 5 As 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
Immersed under a pressure of / cm ² for 3 hours to obtain a modified wood in which an insoluble incombustible compound containing barium phosphate was produced and fixed.

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

Comparative Example 1 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.

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.

[0045]

[Table 1]

As is clear from Examples 1 to 5 and Comparative Example, Examples 1 to 5 maintained flame retardancy and all had a high anti-swelling ratio (ASE) of 50% or more.

[0047]

According to the production method of the present invention, the flame retardancy of wood,
A modified wood having excellent dimensional stability was obtained.

Claims (3)

[Claims] 1. A modified wood having an insoluble non-combustible compound, which is a reaction product of two or more water-soluble compounds impregnated in a raw wood, fixed therein, in a vapor atmosphere of a formaldehyde derivative and in the presence of an acid catalyst. A method for producing modified wood, which comprises heating to formal. 2. The method for producing modified wood according to claim 1, wherein at least one kind of paraformaldehyde, trioxane and tetraoxane is used as the formaldehyde derivative. 3. The method for producing a modified wood according to claim 1, wherein the acid catalyst is at least one selected from the group consisting of sulfur dioxide, hydrogen chloride, chloride, sulfate, phosphite and boric acid. .