JP7437204B2 - Wood impregnating agent composition, wood impregnating agent kit, and method for producing blackened wood - Google Patents

Description

TECHNICAL FIELD The present invention relates to a wood impregnating agent composition, a wood impregnating agent kit, and a method for producing blackened wood.

Conventionally, wood is modified to improve its mechanical strength, water resistance, and the like. As one of the modification methods, there is a method of impregnating a thermosetting resin and thermosetting it. As the thermosetting resin, resol type phenolic resin is widely used.
However, resol type phenolic resins generally exhibit a yellowish brown to reddish brown color, and when heat cured, the color darkens to a deep yellowish brown to deep reddish brown, so they are not suitable for applications that require black wood.

As methods for blackening wood, there are known methods of dyeing wood using water-soluble iron salts and tannins, and methods of dyeing wood using black dye. Tannins develop color by reacting with iron ions in water-soluble iron salts. When water-soluble iron salts and tannins are contained in the same liquid, they react to form a precipitate. Therefore, in methods using water-soluble iron salts and tannins, treatment with a chemical solution containing a water-soluble iron salt and treatment with a chemical solution containing tannins are generally performed separately.

Wood may be treated with both blackening and modification.
In Patent Document 1, in order to perform the dyeing process and the lamination process simultaneously in the production of reinforced black laminate, a wood veneer is treated with a water-soluble iron salt and dried, and then treated with a condensate of tannin and lower aldehyde and heated. It has been proposed that the material be treated with a mixture with a curable resin, laminated and heated under pressure.
Patent Document 2 proposes a method of pre-treating a thin wood board with an aqueous solution of a basic substance and then dyeing it with a black direct dye, as a method for manufacturing thin wood boards that do not cause discoloration through post-treatment such as resin impregnation. There is.

Japanese Unexamined Patent Publication No. 52-44216 Japanese Unexamined Patent Publication No. 58-147307

However, the method of Patent Document 1 requires several days to impregnate wood with a water-soluble iron salt solution, and then is further treated with a mixture, resulting in a long treatment time and poor productivity.
The method of Patent Document 2 also requires a long processing time and is inferior in productivity because dyeing is repeated over several days. If the dyed wood is then modified by post-treatment such as resin impregnation, the treatment time becomes even longer.

The present invention provides a wood impregnating agent composition that can blacken and modify wood with a single impregnation treatment and that provides excellent jet blackness of the resulting blackened wood, and a method for producing blackened wood using the same. The purpose is to provide.

The present invention has the following aspects.
[1] Contains a resol type phenolic resin with a weight average molecular weight of 550 or less, tannin, and a water-soluble iron salt,
The ratio of the solid content of the tannin to the total of the solid content of the resol type phenolic resin and the solid content of the tannin is 40 to 97% by mass,
A wood impregnating agent composition, wherein the ratio of iron content of the water-soluble iron salt to the solid content of the tannin is 0.4 to 1.6% by mass.
[2] A first container containing a first agent containing a resol type phenolic resin having a weight average molecular weight of 550 or less and tannin, and a second container containing a second agent containing a water-soluble iron salt. and
The ratio of the solid content of the tannin to the total of the solid content of the resol type phenolic resin and the solid content of the tannin is 40 to 97% by mass,
A wood impregnating agent kit, wherein the ratio of iron content of the water-soluble iron salt to the solid content of the tannin is 0.4 to 1.6% by mass.
[3] A method for producing blackened wood, which comprises impregnating wood with the wood impregnating agent composition of [1] above and thermally curing it.

According to the present invention, there is provided a wood impregnating agent composition that enables blackening and modification of wood with a single impregnation treatment, and provides excellent jet blackness of the obtained blackened wood, and production of blackened wood using the same. I can provide a method.

It is a photograph showing the blackening evaluation results (wood) of Test Example 2. It is a photograph showing the blackening evaluation results (paper base material) of Test Example 3.

In the present invention, "water-soluble" refers to dissolving 1% by mass or more in neutral water at room temperature (for example, 25° C.).
The weight average molecular weight (hereinafter also referred to as "Mw") of the resol type phenolic resin is a value measured by gel permeation chromatography (hereinafter also referred to as "GPC") in terms of standard polystyrene.
The solid content of the resol type phenolic resin and tannin indicates the nonvolatile content. The nonvolatile content is measured by the following measurement method.
Nonvolatile content measurement method: Weigh the mass C ₁ (g) of an aluminum foil dish (inner diameter 50 mm, height 15 mm), and add the sample (resol type phenolic resin or tannin) to it so that it weighs 1.5 ± 0.1 g. Accurately weigh the sample, and let the specific mass of the sample be the sample mass S (g) before drying. This aluminum foil plate was placed in a thermostat kept at 135 ± 1°C in advance, and after drying for 60 ± 2 minutes, it was left to cool in a desiccator, and its mass C ₂ (g) was measured. . From the results, calculate the sample mass D after drying (mass of the sample remaining on the aluminum foil plate after drying process) (g) using the following formula (1), and calculate the nonvolatile content using the following formula (2). .
D=C ₂ -C ₁ ...(1)
Non-volatile content (%) = D/S x 100 (2)
Unless otherwise specified, pH is a value at 25°C.

[Wood impregnating agent composition]
A wood impregnating agent composition (hereinafter also referred to as "the present composition") according to one embodiment of the present invention includes a resol type phenolic resin having a weight average molecular weight of 550 or less, tannin, and a water-soluble iron salt.
The present composition may further contain other components, as necessary, within a range that does not impair the effects of the present invention.

<Resol type phenolic resin>
A resol type phenolic resin is a reaction product of phenols and aldehydes in the presence of an alkali catalyst.
When phenols and aldehydes are reacted in the presence of an alkali catalyst, an addition reaction occurs in which the aldehyde is added to the aromatic ring of the phenol, followed by a condensation reaction to form a polymer.

Phenols are compounds having an aromatic ring and a hydroxyl group bonded to the aromatic ring, such as phenol, alkylphenol (o, m, p cresol, o, m, p ethylphenol, xylenol isomers, etc.) ), polyaromatic ring phenols (α, β naphthol, etc.), polyhydric phenols (bisphenol A, bisphenol F, bisphenol S, pyrogallol, resorcinol, catechol, hydroquinone, etc.). These phenols may be used alone or in combination of two or more. Among these, practical substances are phenol, o-, m-, and p-cresols, xylenol isomers, resorcinol, and catechol.

The aldehyde is at least one compound selected from the group consisting of compounds having a formyl group and multimers thereof, and examples thereof include formaldehyde, paraformaldehyde, acetaldehyde, propylaldehyde, benzaldehyde, salicylaldehyde, glyoxal, and the like. These aldehydes may be used alone or in combination of two or more. Among these, practical substances are formaldehyde and paraformaldehyde.

The molar ratio of aldehydes to phenols (aldehydes/phenols) (hereinafter also referred to as "F/P") is preferably 1.0 to 4.0, preferably 1.5 to 2.5. It is more preferable that there be. However, when the aldehyde is a multimer such as paraformaldehyde, F/P is a value in terms of monomer.
If F/P is at least the lower limit of the above range, problems such as odor generation or yield reduction due to volatilization of unreacted phenols (free phenols) will not occur. If F/P is below the upper limit of the above range, a large amount of unreacted aldehydes (free aldehydes) will not remain, formaldehyde will not volatilize in the working environment during the manufacturing process, and it will be safe for workers. Does not harm your health. Furthermore, the amount of aldehydes released from the blackened wood obtained using the present composition is small.
The free phenols are unreacted phenols measured according to the provisions of JIS K6910 5.16.
The free aldehydes are unreacted aldehydes measured according to the provisions of JIS K6910 5.17.

The alkaline catalyst is not particularly limited as long as it can promote the reaction between phenols and aldehydes, and various alkaline substances can be used. Specific examples include hydroxides of alkali metals such as sodium and potassium (sodium hydroxide, potassium hydroxide, etc.), hydroxides of alkaline earth metals such as calcium, magnesium, and barium (calcium hydroxide, magnesium hydroxide, etc.). , barium hydroxide, etc.), inorganic alkaline substances such as sodium carbonate, ammonia; tertiary amines such as triethylamine, trimethylamine, triethanolamine, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU ), organic alkaline substances such as cyclic amines such as 1,5-diazabicyclo[4.3.0]non-5-ene) (DBN); and the like. These alkali catalysts may be used alone or in combination of two or more.

The method of reacting phenols and aldehydes in the presence of an alkali catalyst may be a known method. For example, there is a method in which phenols, aldehydes, an alkali catalyst, water, etc. are charged into a reaction vessel having a stirrer, a reflux device, and a temperature control mechanism, and a desired reaction temperature is maintained for a desired reaction time. After the start of the reaction, an additional alkali catalyst, optional additives, etc. may be added as necessary.

The reaction temperature is preferably 50 to 100°C, more preferably 60 to 80°C. If the reaction temperature is at least the lower limit of the above range, a sufficient reaction rate can be obtained. If the reaction temperature is below the upper limit of the above range, the reaction can be easily controlled.
The reaction time can be, for example, 3 to 8 hours, or even 4 to 6 hours. When the reaction time is within the above range, a resol type phenol resin having a weight average molecular weight of 550 or less can be obtained with a high yield, and the productivity of the resol type phenol resin is excellent.

After reacting phenols and aldehydes in the presence of an alkali catalyst, treatments such as neutralization and dilution may be performed as necessary.
The acid used for neutralization may be any acid that can neutralize the alkali catalyst, and examples thereof include boric acid, sulfuric acid, hydrochloric acid, phosphoric acid, lactic acid, and formic acid.
When neutralizing an alkali catalyst with an acid, the combination of the alkali catalyst and the acid is preferably one in which the salt (neutralized salt) of the alkali catalyst and the acid is water-soluble. If the neutralized salt is water-soluble, the impregnating properties of the present composition into wood will be better. Examples of such a combination of an alkali catalyst and an acid include a combination of sodium hydroxide and boric acid.

The solid content concentration of the resol-type phenolic resin is preferably 30% by mass or more, more preferably 40% by mass or more, and may be 100% by mass, based on 100% by mass of the resol-type phenolic resin.

The resol type phenolic resin may be liquid or solid. A liquid resol type phenol resin is preferable because it has excellent miscibility with other materials.

The pH of the resol type phenolic resin is preferably 6.0 to 10.0, more preferably 7.0 to 8.0. If the pH is equal to or higher than the lower limit, the solubility in water will be good, and the composition will have better permeability into wood. If the pH is below the above upper limit, it is economical from the viewpoint of the amount of alkali catalyst used.

The Mw of the resol type phenolic resin is 550 or less, preferably 400 or less, and more preferably 350 or less. If the Mw of the resol type phenolic resin is below the upper limit, the solubility of the resol type phenol resin in water and the permeability of the present composition into wood will be excellent.
The Mw of the resol type phenolic resin is preferably as low as possible in terms of solubility in water and permeability into wood, but from the viewpoint of poisonous substances, it is preferably 300 or more, and more preferably 350 or more.
The Mw of the resol type phenolic resin can be adjusted by adjusting the reaction time, reaction temperature, amount of catalyst, etc. when phenols and aldehydes are reacted in the presence of an alkali catalyst.

<Tannins>
Tannins react with the iron ions of water-soluble iron salts to form poorly water-soluble, black salts.
As tannins, those that are water-soluble are preferred.

Examples of tannins include tannic acid (quintuple tannin), mimosa tannin, persimmon tannin, gallic tannin, and the like. Among these, tannic acid and mimosa tannin are preferred in terms of solubility. These tannins may be used alone or in combination of two or more.

<Water-soluble iron salt>
Examples of water-soluble iron salts include iron (II) chloride, iron (II) sulfate, iron citrate, iron lactate, sodium iron citrate, ammonium iron citrate, and the like. Among these, iron(II) chloride and iron(II) sulfate are preferable in terms of solubility and cost. These water-soluble iron salts may be used alone or in combination of two or more.

<Other ingredients>
Other ingredients are not particularly limited, and include, for example, liquid media such as water and organic solvents; reducing sugars, non-reducing sugars, hardening accelerators, surfactants, emulsion stabilizers, flame retardants, insect repellents, and preservatives. , urea resin, melamine resin and the like.

The organic solvent is preferably one that is miscible with water, and examples thereof include alcohol solvents such as methanol, ethanol, butanol, and propanol. These organic solvents may be used alone or in combination of two or more.

As curing accelerators, ammonium salts (triammonium phosphate, ammonium carbonate, ammonium hydrogen carbonate, ammonium sulfate, ammonium chloride, ammonium citrate, ammonium acetate, etc.), phosphates (potassium phosphate, sodium phosphate, triphosphate, etc.) Examples include orthophosphates such as ammonium, hypophosphites such as sodium hypophosphite, condensed phosphates, etc.), carbonates (sodium carbonate, ammonium carbonate, etc.), and glycine. These curing accelerators may be used alone or in combination of two or more.

<Composition of the present composition>
In this composition, the ratio of the solid content of tannin (hereinafter also referred to as "tannin/resin ratio") is 40 to 97% by mass with respect to the total 100% by mass of the solid content of the resol type phenolic resin and the solid content of tannin. It is preferably 50 to 90% by mass, more preferably 60 to 85% by mass, and even more preferably 65 to 80% by mass. When the tannin/resin ratio is at least the above lower limit, the resulting blackened wood will have excellent jet blackness and the composition will have excellent liquid stability. If the tannin/resin ratio is below the above upper limit, a sufficient modification effect by the resol type phenol resin can be obtained, and the mechanical strength of the blackened wood will be excellent.

The ratio of iron (Fe) in the water-soluble iron salt to 100 mass% solid content of tannin (hereinafter also referred to as "Fe/tannin ratio") is 0.4 to 1.6 mass%, and 0.6 to 1.4% by mass is preferred, and 0.8 to 1.2% by mass is more preferred. When the Fe/tannin ratio is equal to or higher than the lower limit, the resulting blackened wood will have excellent jet blackness (black depth). When the Fe/tannin ratio is below the above-mentioned upper limit, the liquid stability of the present composition is excellent, and the resulting blackened wood can have an even and uniform hue.

The total ratio of the solid content of the resol type phenolic resin, the solid content of tannin, and the water-soluble iron salt to 100% by mass of the present composition is preferably 20% by mass or more, more preferably 50% by mass or more, and 100% by mass. There may be.

Among other components, the content of the organic solvent is preferably 30% by mass or less, particularly preferably 0% by mass, based on 100% by mass of the present composition. That is, it is particularly preferable that the present composition does not contain an organic solvent. If the composition contains an organic solvent, it may not be usable depending on the application. As long as the content of water in the composition is at most the above-mentioned upper limit, the composition can be applied to a variety of uses, especially if the composition does not contain an organic solvent.

The content of additives among other components is preferably 30% by mass or less, more preferably 10% by mass or less, based on the total 100% by mass of the solid content of the resol type phenolic resin and the solid content of tannin. The lower limit is not particularly limited and may be 0% by mass.

The solid content concentration of the present composition can be appropriately set in consideration of the balance between permeability into wood and desired properties of the modified wood.
For example, the lower the solid content concentration of the present composition, the lower the viscosity, and the easier it is to penetrate into wood. On the other hand, the higher the solid content concentration of the present composition, the easier it is to obtain a modification effect by impregnating with the present composition, and for example, the degree of blackening and mechanical strength tend to improve.
When the present composition is directly impregnated into wood, the solid content concentration of the present composition is preferably 5 to 70% by mass, more preferably 10 to 30% by mass.
During production, the composition may be made to have a higher solid content concentration than that used when impregnating wood, and may be diluted with water or the like to achieve the desired solid content concentration during use (during impregnation into wood).

The viscosity of the present composition is preferably 1 to 300 mPa·s, more preferably 1 to 100 mPa·s, even more preferably 1 to 50 mPa·s. If the viscosity of the present composition is at least the above lower limit, the fixing properties will be better, and if the viscosity is at or below the above upper limit, the composition will have better permeability into wood. The viscosity is a value measured using a B-type viscometer at 25°C.

This composition is used in the method for producing blackened wood described below.
The present composition can be produced, for example, by mixing a resol type phenolic resin, tannin, water-soluble iron salt, and other components as necessary.
Although the mixing order of each component is not particularly limited, it is preferable to mix the resol type phenolic resin and tannin, and then mix the resulting mixture with the water-soluble iron salt. By mixing the tannin with the resol type phenolic resin in advance before mixing it with the water-soluble iron salt, the tannin and the resol type phenolic resin can be mixed uniformly, and the impregnating property is improved.
An example of a preferred method for producing the present composition is a method of mixing the first and second parts of the wood impregnating agent kit described below. The first agent contains a resol type phenolic resin and tannin. For convenience, tannin alone may be treated as the first agent. The second agent contains a water-soluble iron salt.
Although this composition has excellent liquid stability, when stored for a long period of time (for example, 30 days or more), the resol-type phenolic resin and tannin react with each other during storage, producing sediment, which causes blackened wood. Unevenness may occur in the hue. The first part containing resol-type phenolic resin and tannin and the second part containing water-soluble iron salt are stored in a state where they are immiscible, and when impregnating wood with this composition, the first part and the second part contain water-soluble iron salt. By preparing the present composition by mixing it with the second agent, it is possible to suppress the occurrence of uneven hue. The time from mixing the first part and the second part to starting the impregnation treatment of the wood with the present composition is preferably less than 6 hours, more preferably 3 hours or less, and particularly preferably 1 hour or less. .

The present composition described above contains a resol-type phenolic resin, tannin, and a water-soluble iron salt, and the solid content of tannin is the ratio of the solid content of tannin to the total solid content of resol-type phenolic resin and solid content of tannin. /resin ratio) is 40 to 97% by mass, and the ratio of iron content of the water-soluble iron salt to the solid content of tannin (Fe/tannin ratio) is 0.4 to 1.6% by mass, so one-time impregnation It is possible to blacken and modify wood through treatment, and the resulting blackened wood has excellent jet-black properties. Furthermore, although it contains tannins and water-soluble iron salts in the same liquid, it has excellent liquid stability and does not easily produce sediment during storage. Therefore, it is possible to obtain blackened wood with no uneven hue due to sediment. Furthermore, since the blackened wood obtained using the present composition contains a cured product of the present composition at least on the surface and its vicinity, it has better mechanical strength, water resistance, and dimensional stability than the wood before modification. Excellent in etc.

[Wood impregnating agent kit]
A wood impregnating agent kit according to one aspect of the present invention includes a first container containing a first agent containing a resol-type phenolic resin having a weight average molecular weight of 550 or less and tannin, and a first agent containing a water-soluble iron salt. and a second container containing two drugs. Further, the ratio of the solid content of the tannin to the total solid content of the resol type phenolic resin and the solid content of the tannin (tannin/resin ratio) is 40 to 97% by mass, and the water soluble content with respect to the solid content of the tannin is The iron content ratio (Fe/tannin ratio) of the iron salt is 0.4 to 1.6% by mass.
The first agent and the second agent may each further contain other components.

The resol type phenolic resin, tannin, water-soluble iron salt, and other components are as described above, and preferred embodiments are also the same.
The preferable ranges of the tannin/resin ratio and the Fe/tannin ratio are as described above.
The preferred range of the solid content concentration of each of the first agent and the second agent is the same as the preferred range of the solid content concentration of the present composition.
Preferably, the first agent does not contain a water-soluble iron salt.
Preferably, the second agent does not contain tannin.

The wood impregnating agent kit is prepared by mixing the first agent and the second agent to form the present composition, which is used in the method for producing blackened wood described below.

[Method for manufacturing blackened wood]
In the method for producing blackened wood according to one aspect of the present invention, wood is impregnated with the present composition and then thermally cured. This results in blackened wood.
After impregnating the wood with the composition, the wood impregnated with the composition may be dried before heat curing.

Examples of the wood include solid wood and wood materials.
Examples of solid wood include paulownia wood, cedar wood, cypress wood, pine wood, cypress wood, Spanish mackerel wood, and pine wood. The form of solid wood may be sawn timber, sawn board, etc.

Wood materials are made by disassembling solid wood into multiple elements (components) and reorganizing them. Examples of the wood material include a wood shaft material and a wood surface material.
Examples of the wood shaft material include laminated wood, orthogonal laminated wood, and laminated veneer wood.
Examples of the wood surface material include plywood, orthogonal laminated board, veneer laminate, block board, veneer, and wood board.

A wood board is a plate-shaped product made of wood fibers or small pieces of wood hardened with a binder. Wood chips are small pieces of wood, and are a general term for chips, flakes, wafers, strands, and other cut pieces and crushed pieces. Wood fibers are made by steaming small pieces of wood with high-temperature, high-pressure steam and defibrating them using a refiner or the like.
Examples of wood boards (fiberboards) using wood fibers include IB (insulation board), MDF (medium density fiberboard), and HB (hard board). These are mainly distinguished by density.
Examples of the wood board using small pieces of wood include particle board and OSB (oriented strand board). In particle board and OSB, the size and shape of the wood particles become irregular due to the crushing process, etc., but the quality is controlled by classification etc. in the subsequent manufacturing process.
However, the properties of the products vary depending on the size, shape, and arrangement of the wood fibers or wood chips, and intermediate products also exist because the manufacturing process is similar. Such products shall also fall under the category of wood boards.
The wood to be modified can be arbitrarily selected depending on the purpose.

The method for impregnating wood with the present composition is not particularly limited, and any known method for impregnating wood with a chemical solution can be applied.
Examples of the impregnation method include impregnation treatment under reduced pressure, impregnation treatment using consolidation processing, and impregnation treatment using ultrasonic waves.

In the vacuum pressure impregnation treatment, the wood and the present composition are placed in a sealable container, the pressure inside the container is reduced, and then the pressure is increased. After that, remove the wood from the container and dry it if necessary.
In this method, the air in the wood is removed when the pressure is reduced, and the composition penetrates into the wood during the subsequent pressurization.
The reduced pressure impregnation treatment can be carried out, for example, using a known reduced pressure impregnation apparatus in accordance with JIS A 9002 "Pressure method for preserving wood materials."

In the impregnation treatment by consolidation, wood is consolidated, and the consolidated wood is immersed in the present composition under normal pressure. Thereafter, the wood in the composition is taken out and dried if necessary.
The compaction process can be performed, for example, by a roll press. In a roll press, a plate-shaped piece of wood is passed between one or more pairs of rolls, and the pieces of wood are compressed in the thickness direction by the pairs of rolls. Consolidation treatment conditions are not particularly limited, but for example, in the case of plate-shaped wood, conditions may be mentioned such that the thickness of the wood after consolidation treatment is about 40 to 50% of the thickness of the wood before consolidation treatment.
The immersion conditions for immersing the wood in the present composition are not particularly limited, but include, for example, conditions in which the present composition is immersed at 35 to 40° C. for 3 hours, or for an equivalent period of time.

In the impregnation treatment using ultrasonic waves, wood is immersed in the present composition under normal pressure, the wood is pressurized with a horn that transmits ultrasonic vibrations to the wood, and ultrasonic waves are applied in this state. Thereafter, the wood in the composition is taken out and dried if necessary.
In this method, when applying ultrasonic waves, the tip of the horn reciprocates and repeatedly impacts the wood. As a result, ultrasonic vibrations are transmitted to the wood, and the cavitation (cavitation phenomenon) and defoaming effect, which are the characteristics of ultrasonic waves, promote the evacuation of air from the wood. Therefore, impregnation is carried out effectively in a short period of time.

When drying wood impregnated with the present composition, the drying method may be natural drying, drying by heating, or a combination thereof. For example, after air drying overnight, it may be dried by heating.
The heating temperature during drying is preferably 50 to 90°C. If the heating temperature is equal to or higher than the lower limit value, the drying efficiency is good, and if the heating temperature is lower than the upper limit value, the curing of the present composition is difficult to proceed. The drying time varies depending on the drying temperature, but is, for example, 1 to 6 hours.

The curing temperature (heating temperature) when thermosetting the present composition is preferably 120 to 220°C, more preferably 140 to 200°C, even more preferably 160 to 180°C. If the curing temperature is above the lower limit value, the curing reaction of the present composition will easily proceed, and if it is below the upper limit value, it will be possible to suppress the darkening of the resol type phenolic resin during heat curing, and the resulting blackening. The jet blackness of the wood is better.
The curing time (heating time) varies depending on the curing temperature, but is, for example, 5 to 60 minutes.

EXAMPLES Below, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the examples. In each of the following examples, "parts" and "%" indicate "parts by mass" and "% by mass," respectively, unless otherwise specified. The solid content was measured by the measurement method described above.

Tannin: Mimosa tannin, "MIMOSA NT POWDER" manufactured by UCL COMPANY (PTY) LTD, solid content 100%.
Water-soluble iron salt: iron (II) sulfate heptahydrate, manufactured by Kanto Kagaku Co., Ltd., solid content 100%.
Phenol resin: Liquid resol type phenol resin obtained in Production Example 1 described below, solid content 50%, Mw = 310, pH = 7.5.

(Production example 1: Production of phenolic resin)
A reaction vessel was charged with 1300.0 g of formaldehyde and 1492.0 g of phenol (formaldehyde/phenol molar ratio = 1.80), and 117.0 g of a 48% aqueous sodium hydroxide solution (9.0% relative to phenol) was added thereto. . Next, the temperature was raised to 65° C., and the reaction was carried out for 4.5 hours. Thereafter, the liquid temperature was lowered to 45° C., and boric acid was added until pH=7.5 to obtain a phenol resin. The obtained phenol resin was in the form of an aqueous solution, and no insoluble matter was observed.

<Test Example 1>
(Preparation of first agent)
Example 1 Tannin and phenolic resin were mixed so that the tannin/resin ratio was 80%, 70%, 50% or 30%, and diluted with water so that the total solid content concentration was 20%. ~3, the first agent of Comparative Example 1 was obtained.

(Evaluation of liquid stability of the first agent)
The first agent was stored at 25° C. for 30 days immediately after mixing the tannin and phenol resin. The first agent was visually observed at each of 0 days (immediately after mixing the tannin and phenolic resin), 7 days, 17 days, and 30 days of storage to evaluate the presence or absence of precipitates. The results are shown in Table 1.

<Test Example 2>
(Preparation of chemical solution)
A first agent was obtained in the same manner as in Example 2. Separately, measure an amount of water-soluble iron salt such that the Fe/tannin ratio of the chemical solution (wood impregnating agent composition, hereinafter the same applies) is 1.0%, and dissolve it in water so that the overall solid content concentration is 20%. A second agent was obtained. The drug solution of Example 4 was obtained by mixing the first agent and the second agent.
A first agent was obtained by diluting tannin with water so that the total solid content concentration was 20%. Separately, an amount of water-soluble iron salt such that the Fe/tannin ratio of the chemical solution was 1.0% was measured, and dissolved in water to give a total solid content concentration of 20% to obtain a second agent. A chemical solution of Comparative Example 2 was obtained by mixing the first agent and the second agent.

(Evaluation of blackening 1: Evaluation on wood)
A cedar veneer (100 mm x 50 mm x 3 mm) was placed in a container of a reduced pressure impregnation device, and vacuum treated at 25° C. and a pressure of -90.66 kPa for 15 minutes. A chemical solution was put into the container under vacuum, and after being held for 1 hour, the pressure was opened and the container was left standing at 35° C. and normal pressure for 15 minutes. Thereafter, the cedar veneer was taken out of the container, air-dried overnight, and then heated and dried in a dryer at 60° C. for 1 hour. This cedar veneer was subjected to hot press treatment at 140° C. for 30 minutes to obtain blackened wood.
A photograph of the obtained blackened wood is shown in FIG.

As shown in FIG. 1, the blackened wood obtained using the chemical solution of Comparative Example 2 (tannin/resin ratio 100%) had uneven hue. In contrast, the blackened wood obtained using the chemical solution of Example 4 (tannin/resin ratio 70%) showed no uneven hue.

<Test Example 3>
(Preparation of chemical solution)
A chemical solution of Example 5 was obtained in the same manner as in Example 4.
Chemical solutions of Example 6 and Comparative Example 3 were obtained in the same manner as in Example 4 except that the tannin/resin ratios were set to 50% and 30%, respectively.

(Evaluation of blackening 2: Evaluation on paper base material)
In order to easily evaluate the effect of chemical solutions on hue, a paper base material was used instead of wood. As the paper base material, filter paper (ADVANTECH Filter Paper 5C 90 mm) was used.
The paper base material was immersed in the chemical solution to impregnate the paper base material with the chemical solution. The paper base material was taken out from the chemical solution and heated in a dryer at 140°C, 160°C, 180°C, or 200°C for 10 minutes to obtain a blackened paper base material.
A photograph of the obtained blackened paper base material is shown in FIG.
Further, the hue (L, a, b) of each blackened paper base material was measured using a color difference meter. The results are shown in Table 2. The closer the L value is to 0, the better the jet blackness (black density) is.

As shown in FIG. 2 and Table 2, when the same chemical solution is used, the lower the curing temperature (heating temperature), the better the jet blackness tends to be. When the curing temperature was the same, the modified paper base material obtained using the chemical solutions of Examples 5 and 6 had better jet blackness than the modified paper base material obtained using the chemical solution of Comparative Example 3.

<Test Example 4>
(Preparation of chemical solution)
Chemical solutions of Examples 7 to 9 and Comparative Examples 4 to 6 were obtained in the same manner as in Example 4 except that the Fe/tannin ratio was adjusted to the value shown in Table 3. In Table 3, the amount of water-soluble iron salt added indicates the mass ratio of water-soluble iron salt to the solid content of tannin.

(Evaluation of hue)
Blackened wood was obtained in the same manner as in Test Example 2 except that the obtained chemical solution was used. Regarding the hue of the obtained blackened wood, the darkness of the black color and the presence or absence of unevenness were evaluated. The results are shown in Table 3. When the black color was deep and no unevenness was observed, it was evaluated as "good," when the black color was light, it was evaluated as "thin," and when unevenness was observed, it was evaluated as "uneven."

(Evaluation of liquid stability)
After mixing the first agent and the second agent, the chemical solution was allowed to stand in a constant temperature bath at 40° C., and the stability of the solution was evaluated based on the presence or absence of precipitation. The results are shown in Table 3. A case where no precipitate was observed after being allowed to stand for 4 hours was rated as "good", and a case where a precipitate was generated shortly after mixing the first part and the second part was rated as "unstable".

Claims (3)

Contains a resol type phenolic resin having a weight average molecular weight of 550 or less, tannin, and a water-soluble iron salt,
The ratio of the solid content of the tannin to the total of the solid content of the resol type phenolic resin and the solid content of the tannin is 40 to 97% by mass,
A wood impregnating agent composition, wherein the ratio of iron content of the water-soluble iron salt to the solid content of the tannin is 0.4 to 1.6% by mass. A first container containing a first agent containing a resol type phenolic resin having a weight average molecular weight of 550 or less and tannin, and a second container containing a second agent containing a water-soluble iron salt. ,
The ratio of the solid content of the tannin to the total of the solid content of the resol type phenolic resin and the solid content of the tannin is 40 to 97% by mass,
A wood impregnating agent kit, wherein the ratio of iron content of the water-soluble iron salt to the solid content of the tannin is 0.4 to 1.6% by mass. A method for producing blackened wood, comprising impregnating wood with the wood impregnating agent composition according to claim 1 and thermally curing the wood.