JP7577007B2 - Manufacturing method for decorative article made of non-combustible wood, and decorated article, as well as manufacturing method for surface-treated article made of non-combustible wood and surface-treated article - Google Patents

Description

The present invention relates to a method for manufacturing a decorative article made of non-combustible wood in which non-combustible wood that has been subjected to a fireproofing treatment is decorated by inkjet printing, a decorative article made of non-combustible wood, and a method for manufacturing a surface-treated article made of non-combustible wood and a surface-treated article.

Conventionally, fireproof wood has been proposed that is manufactured by injecting fireproofing agents such as boron-based (borax and boric acid, etc.) and phosphoric acid-based (ammonium phosphate, etc.) agents into wood (see, for example, Patent Document 1). Such fireproof wood can be used, for example, as a building material to prevent fires.

JP 2018-103452 A JP 2018-70758 A

Here, as mentioned above, when non-combustible wood is used, for example, as a building material, it would be preferable to be able to decorate the non-combustible wood with ink or the like, as this would broaden its applications. However, Patent Document 1 does not mention anything about decorating non-combustible wood.

The raw material for non-combustible wood is wood that has tubes (ducts) that allow water to pass through. These tubes also exist in non-combustible wood, and when directly inkjet printing is performed using water-based ink, for example, the inside of the ducts is exposed on the surface of the wood that has been processed into a board, causing bleeding along the ducts and reducing the reproducibility of fine lines.

On the other hand, for example, Patent Document 2 proposes a method of applying a surface treatment liquid to the surface of wood to form a surface treatment layer and then performing inkjet printing on the surface treatment layer in order to suppress the bleeding that occurs when inkjet printing is performed directly on ordinary wood, which is not fireproof wood.

Therefore, even when performing inkjet printing on non-combustible wood, it is possible to apply a surface treatment liquid to the non-combustible wood to form a surface treatment layer before inkjet printing.

However, the applicant's experiments have shown that when a surface treatment liquid is applied to non-combustible wood, efflorescence occurs.

Specifically, as mentioned above, when manufacturing fireproof wood by fireproofing with a boron- or phosphoric acid-based fireproofing agent, an auxiliary agent is added, but it has been found that the agent added as an auxiliary has high hygroscopicity, and as a result of applying a surface treatment liquid, it causes an efflorescence phenomenon in which the surface turns white due to precipitated crystals. An auxiliary agent is an agent used to increase the solubility of boron or phosphoric acid in water and promote the penetration of the fireproofing agent into the fireproof wood; for example, an ammonium salt such as diammonium phosphate is used. Such an auxiliary agent has a high affinity for water molecules and reacts with the water contained in the surface treatment liquid, causing the efflorescence phenomenon mentioned above.

If inkjet printing is performed while efflorescence is occurring, the quality of the printed image will be reduced by the precipitated crystals. In addition, the crystals precipitated by efflorescence cannot be easily removed from non-combustible wood, and if they are removed by force, marks will remain on the surface, reducing the quality of the decorative item.

The present invention aims to provide a method for manufacturing a decorative article made of non-combustible wood and a decorative article, which can suppress the efflorescence of non-combustible wood and the deterioration of printed images due to the efflorescence, as well as a method for manufacturing a surface-treated article made of non-combustible wood and a surface-treated article.

The method for producing a decorative article made of non-combustible wood of the present invention includes a surface treatment liquid application step of applying a surface treatment liquid containing at least water, a colorant fixing component, and a surface tension adjuster to non-combustible wood that has been subjected to a fire-retardant treatment, and a printing step of performing inkjet printing on the non-combustible wood to which the surface treatment liquid has been applied, wherein the amount of the surface treatment liquid applied to the non-combustible wood in the surface treatment liquid application step is 50 g/ ^m2 or less.

According to the method for manufacturing a decorative article made of non-combustible wood of the present invention, in the surface treatment liquid application step in which a surface treatment liquid containing at least water, a colorant fixing component and a surface tension adjuster is applied to non-combustible wood that has been subjected to a fireproofing treatment, the amount of surface treatment liquid applied to the non-combustible wood is 50 g/ ^m2 or less, so that efflorescence of the non-combustible wood can be suppressed and deterioration of printed images due to efflorescence can be suppressed.

FIG. 1 is a diagram for explaining a method for measuring the pressure of a coating member against a noncombustible member.

The manufacturing method for a decorative article made of non-combustible wood and one embodiment of the decorative article of the present invention will be described in detail below with reference to the drawings.

The manufacturing method for a decorative article of a noncombustible member of this embodiment includes a surface treatment liquid application step of applying a surface treatment liquid containing at least water, a colorant fixing component, and a surface tension adjuster to noncombustible wood that has been subjected to a fireproofing treatment, and a printing step of performing inkjet printing on the noncombustible wood to which the surface treatment liquid has been applied, in which the amount of the surface treatment liquid applied to the noncombustible wood in the surface treatment liquid application step is 50 g/ ^m2 or less. Note that in this specification, the amount of the surface treatment liquid is the amount measured immediately after the surface treatment liquid is applied to the noncombustible wood.

This makes it possible to suppress the efflorescence phenomenon that occurs when the water contained in the surface treatment solution reacts with the auxiliary agent contained in the non-combustible wood, and also to suppress the deterioration of the printed image caused by the efflorescence phenomenon.

The decorative article of this embodiment is obtained by carrying out the manufacturing method of the decorative article of the noncombustible member of the above embodiment, and specifically includes noncombustible wood obtained by subjecting wood to a fireproofing treatment, a surface treatment layer formed on the surface of the noncombustible wood using a surface treatment liquid containing at least water, a colorant fixing component, and a surface tension adjuster, and an inkjet printed layer formed on the surface treatment layer. The surface treatment layer of the decorative article of this embodiment is formed by applying the surface treatment liquid to the noncombustible wood in an amount of 50 g/ ^m2 or less.

The fireproof wood used in this embodiment is a component manufactured by injecting fireproofing agents such as boron-based (e.g., borax and boric acid) or phosphoric acid-based (e.g., ammonium phosphate) into wood. Fireproof wood is used, for example, as a building material, but its uses are not limited to this.

Below, we will explain the mechanism behind non-combustible wood. When non-combustible wood is exposed to heat, it first undergoes an endothermic decomposition reaction, lowering the surrounding temperature. When it is heated to a high temperature, the injected fire-retardant agent foams and creates a layer of glass. This layer of foamed glass envelops the wood, blocking out oxygen and heat, making it less likely to burn.

It is preferable to use non-combustible wood that has passed a certification test set by the government. The non-combustible wood certification test generally involves two tests: a heat generation test and a gas toxicity test.

The heat generation test is carried out using a cone calorimeter. The cone calorimeter is designed to measure the amount of combustion by measuring the amount of oxygen lost from the test piece. The Ministry of Land, Infrastructure, Transport and Tourism has the following three standards for certification of fireproof wood:
1. The total heat generation amount for 20 minutes after the start of heating is 8 MJ/m2 ^or less.
2. The heat generation rate within 20 minutes after the start of heating must not exceed 200Kw/ ^m2 for 10 seconds or more.
3. There must be no cracks reaching the rear surface or deformations harmful to fire prevention within 20 minutes after the start of heating.

In addition, products that pass the heat generation test are then subjected to gas toxicity tests. They are required not to emit smoke or gases that are harmful to evacuation.

Gas toxicity tests are evaluated by the time it takes for mice to stop behaving when exposed to the combustion gases generated by heating a test specimen (220 mm square).

Here, wood, the raw material for non-combustible wood, contains tubes (ducts) that allow water to pass through. The distribution of these ducts is what creates the wood grain pattern on the surface of the wood.

On the other hand, as described above, when the surface of wood processed into a board shape has the inside of the vessels exposed, printing with water-based ink on the surface will cause bleeding along the vessels and reduce fine line reproducibility. In contrast, by performing surface treatment with the surface treatment liquid of this embodiment, the colorant fixing component in the surface treatment liquid (e.g., cationic water-dispersible resin) controls the wetting and spreading of the ink inside the vessels. This makes it possible to form a printed image that is less likely to bleed, has good fine line reproducibility, and has good color development. Specifically, the anionic component contained in the ink reacts with the cationic component contained in the surface treatment liquid, which controls the penetration of ink components such as the colorant into the wood, and allows the colorant to remain on the surface of the wood. The surface treatment liquid will be described in detail later.

Next, we will explain how to apply the surface treatment liquid to non-combustible wood.

As mentioned above, fireproof wood is formed by impregnating wood with fireproofing agents, but the penetration of the fireproofing agents narrows the wood's ducts, making it less wettable than wood that has not been treated with fireproofing.

When wettability is reduced in this way, the contact angle of the surface treatment liquid described above increases, making it difficult to apply the surface treatment liquid uniformly to the non-combustible wood. If the surface treatment liquid is not applied uniformly, it will cause deterioration of the printed image formed on the surface. The contact angle of the surface treatment liquid on the non-combustible wood is an index of wettability, and can be measured by measuring the change in dynamic contact angle over time using the droplet method (measuring device: contact angle meter DM-500, manufactured by Kyowa Interface Science Co., Ltd.). The larger the dynamic contact angle 1 second after the surface treatment liquid (1.0 μL droplet) hits the non-combustible wood, the lower the wettability and the more difficult it is to apply the surface treatment liquid uniformly. Specifically, when the dynamic contact angle of the surface treatment liquid on the non-combustible wood is 10° or more, it is difficult to apply the surface treatment liquid uniformly.

In this embodiment, therefore, the surface treatment liquid is applied to the surface of the non-combustible wood by a contact application method. This allows the surface treatment liquid to penetrate inside the tubes of the non-combustible wood, and the surface treatment liquid can be applied evenly to the surface of the non-combustible wood, suppressing uneven application. This in turn improves the quality of the printed image of the decorative article. In particular, as described above, a remarkable effect can be obtained when the dynamic contact angle of the surface treatment liquid with respect to the non-combustible wood is 10° or more.

When applying the surface treatment liquid by a contact application method, an application member such as a sponge is used which absorbs the surface treatment liquid and is then pressed against the non-combustible wood with a certain pressure, causing the surface treatment liquid to flow out and adhere to the surface of the non-combustible wood. However, as mentioned above, in order to apply the surface treatment liquid evenly to the surface of non-combustible wood, which has low wettability, the application member needs to have a certain degree of absorbency.

Specifically, in the surface treatment liquid application step of applying the surface treatment liquid to the non-combustible wood, it is preferable to use an application member having a water absorption of 0.44 g/ ^cm3 or more. This allows the application member to be sufficiently saturated with the surface treatment liquid, and allows the surface treatment liquid to be uniformly applied to the non-combustible wood. The method for measuring the water absorption will be described in detail later.

In addition, the applicator member adheres to the noncombustible wood by deforming, but if the amount of deformation when pressed is too large, it may be difficult to apply the surface treatment liquid evenly. Therefore, in the surface treatment liquid application process, it is preferable to use an applicator member that deforms by 25 mm or less when pressed with a pressure of 30 kPa. This ensures adhesion between the applicator member and the noncombustible wood, and allows the surface treatment liquid to be applied evenly to the noncombustible wood. The method for measuring the amount of deformation will be described in detail later.

In addition, if the pressure applied when pressing the application member against the noncombustible wood to apply the liquid is low, the surface treatment liquid may not flow out sufficiently from the application member or the adhesion between the application member and the noncombustible wood may decrease, making it difficult to apply the surface treatment liquid evenly to the noncombustible wood. Therefore, in the surface treatment liquid application process, it is preferable to press the application member against the noncombustible wood with a pressure of 5 kPa or more. This allows the surface treatment liquid to flow out sufficiently from the application member, ensures adhesion between the application member and the noncombustible wood, and allows the surface treatment liquid to be applied evenly to the noncombustible wood. The method for measuring the above pressure will be described in detail later.

That is, the conditions for uniformly applying the surface treatment liquid to the surface of non-combustible wood are more preferably to use an application member with a water absorption of 0.44 g/ ^cm3 or more and a deformation amount of 25 mm or less when pressed with a pressure of 30 kPa, and to press the application member against the non-combustible wood with a pressure of 5 kPa or more. In this case, it is preferable that the amount of application of the surface treatment liquid is 50 g/m2 or ^less as described above. More preferably, it is 35 g/m2 ^or less, which allows the drying time to be such that productivity can be sufficiently guaranteed.

The amount of the surface treatment liquid applied to the non-combustible wood is preferably 7 g/m2 or ^more . More preferably, it is 10 g/m2 or ^more . This ensures the image quality of the printed image when inkjet printing is performed after the surface treatment liquid is applied to the non-combustible wood. Also, the surface treatment liquid can be applied uniformly to the non-combustible wood.

The above-mentioned application member may be used to apply the surface treatment liquid to the non-combustible wood by manually pressing the application member against the non-combustible wood, or by using a specified mechanical mechanism to press the application member against the non-combustible wood. In this case, it is preferable that the speed at which the application member is moved over the surface of the non-combustible wood (application speed) is, for example, 300 mm/s.

After applying the surface treatment liquid to the non-combustible wood, it is preferable to dry it before inkjet printing. In this case, it is preferable to dry it at room temperature without heating. This makes it possible to prevent deformation of the non-combustible wood due to heating. On the other hand, it is also possible to perform inkjet printing immediately after applying the surface treatment liquid to the non-combustible wood, that is, without drying the surface treatment liquid. When drying the surface treatment liquid, it is preferable to leave it overnight at 22°C and a humidity of 50%.

Next, we will explain the printing process in which inkjet printing is performed on fireproof wood that has been coated with a surface treatment liquid.

The ink used for inkjet printing is not particularly limited, but is preferably a non-UV curable ink, and is more preferably a water-based ink. In other words, it is preferably an ink containing water, a binder resin, and a coloring material. The ink will be described in detail later.

In addition, inkjet printing can be performed using a general recording head, and there are no particular limitations on the printing method or the device used. After printing, the printed ink is dried, causing water and other volatile components to evaporate from the printed ink, resulting in a decorative article with a printed image formed on the surface of the non-combustible wood. As for drying conditions, it is preferable to heat the printed surface at 80°C for 10 minutes.

According to the method of applying the surface treatment liquid of this embodiment, the surface treatment can be applied uniformly to the non-combustible wood as described above. This allows the wetting and spreading of the ink to be controlled, and it is possible to form a printed image that is less likely to bleed, has good fine line reproducibility, and has good color development. Therefore, for example, when a wood grain pattern is printed on surface-treated non-combustible wood, the wood grain pattern can be reproduced in a way that compares favorably with real wood.

In addition, when a full-color gradation image is printed on surface-treated fireproof wood, the gradation can be reproduced well.

In addition, when a solid CMYK image is printed on surface-treated fireproof wood, the same color development can be achieved as with inkjet paper.

In addition, when printing thin lines of 0.3 mm on surface-treated fireproof wood, bleeding, smearing, and cutting can be prevented.

The above-mentioned surface treatment solution will be described in detail below.

The surface treatment liquid preferably contains at least water, a colorant fixing component, and a surface tension adjuster. The colorant fixing component is preferably a cationic water-dispersible resin, and preferably contains large particles having a median diameter of 1 μm or more and 10 μm or less as measured by dynamic light scattering. It is even more preferable that the surface treatment liquid contains small particles having a median diameter of less than 1 μm as measured by dynamic light scattering.

The surface treatment liquid of this embodiment is preferably used as a surface treatment liquid prior to forming a printed image using a non-UV curable ink (e.g., a water-based ink). By using the surface treatment liquid of this embodiment in advance before printing and then forming a printed image using inkjet ink, the wetting and spreading of the ink can be controlled as described above, and a printed image can be formed that is less likely to bleed, has good fine line reproducibility, and has good color development.

Cationic water-dispersible resin particles are resin particles with a positively charged surface, and can disperse in particulate form without dissolving in water to form an oil-in-water (O/W) emulsion. They may be resins in which cationic functional groups are present on the particle surface, as in the case of self-emulsifying resins, or resin particles that have been surface-treated by attaching a cationic dispersant to the surface.

Representative examples of cationic functional groups include primary, secondary, or tertiary amino groups, pyridine groups, imidazole groups, benzimidazole groups, triazole groups, benzotriazole groups, pyrazole groups, and benzopyrazole groups, and examples of cationic dispersants include primary, secondary, tertiary, or quaternary amino group-containing acrylic polymers, polyethyleneimines, cationic polyvinyl alcohol resins, and cationic water-soluble hyperbranched polyesteramide resins.

The surface charge of the resin particles can be evaluated using a particle charge meter. The surface charge can be calculated by measuring the amount of anions or cations required to neutralize the sample. Specifically, it is preferable that the surface charge is +300 μeq/g or more. As a particle charge meter, a colloid particle charge meter Model CAS manufactured by Nippon Luft Co., Ltd. can be used.

As the water-dispersible resin, it is preferable to use a resin that forms a transparent coating film. In addition, when producing the treatment liquid, it can be blended as an oil-in-water type resin emulsion.

Representative examples include ethylene-vinyl chloride copolymer resin, (meth)acrylic resin, styrene-maleic anhydride copolymer resin, urethane resin, vinyl acetate-(meth)acrylic copolymer resin, vinyl acetate-ethylene copolymer resin, and resin emulsions thereof. Here, "(meth)acrylic resin" refers to both acrylic resin and methacrylic resin. These resins may be used alone or in combination of two or more. As will be described later, resin emulsions in which these resins are combined may also be used. As described above, a positive surface charge can be imparted to these resins by introducing a cationic functional group into them or by surface treating them with a cationic dispersant or the like.

The particle size of the resin particles is not particularly limited, and any combination of particles of different particle sizes can be used. However, from the viewpoint of being easily retained on the surface of the non-combustible wood, it is preferable that the resin particles contain particles with a median diameter (average particle size) of 1 μm or more as measured by dynamic light scattering. In addition, it is preferable that the average particle size of the resin particles is 10 μm or less, which allows the resin particles to penetrate into recesses and voids in the surface of the non-combustible wood while taking advantage of the wood properties of the non-combustible wood.

That is, in non-combustible wood, by setting the median diameter (average particle size) of the resin particles to 1 μm or more and 10 μm or less, a surface treatment layer can be efficiently formed according to the above-mentioned tube size of non-combustible wood. In particular, the tube size (average diameter) of wood varies depending on the classification of softwood and hardwood. For example, the average diameter of hardwood ring-porous ash wood is about 260 μm, and that of diffuse-porous maple wood is about 60 μm. On the other hand, the average diameter of softwood cypress wood is about 10 μm. Thus, the size of the pores in wood varies depending on the species, and since wood is a natural product, there is no substrate with exactly the same distribution of pores. However, by setting the average particle size of the large particles as described above, a surface treatment layer can be formed on a substrate with uneven pores such as wood without reducing the original function of the substrate (hygroscopicity in the case of wood).

Furthermore, it is preferable that the surface treatment liquid also contains small particles having a median diameter (average particle size) of less than 1 μm as measured by dynamic light scattering. This can further improve the water resistance of the ink layer in addition to the above-mentioned image quality.

When using large and small particles, the ratio of the two is preferably about 0.1 to 1.5 small particles to 1 large particle by weight, since if the number of small particles is too small compared to the number of large particles, adhesion will be insufficient, and if the number of small particles is too large, the treatment layer may form a film and hinder the moisture absorption of the wood. In this specification, "weight" and "mass" are used interchangeably.

The average particle size of the resin particles is the volume-based particle size value (median diameter) in the particle size distribution measured by dynamic light scattering. A nanoparticle analyzer nano Partica SZ-100 (Horiba, Ltd.) or the like is used as a dynamic light scattering particle size distribution measuring device, and the water-dispersible resin can be diluted with water to a concentration of 0.5% by mass and measured at 25°C.

In the surface treatment liquid or the ink described below, the resin particles may exist in the form of independent fine particles, or in the form of aggregates of independent fine particles, but the median diameter measured by dynamic light scattering is taken as the "average particle size."

The average particle size of the resin particles is preferably measured in the raw material emulsion state before preparing the surface treatment liquid or ink, since in the case of ink, the influence of the coloring material (pigment particles) can be eliminated, and the measured value can be used as the average particle size in this embodiment.

The average particle size of the large particles is more preferably 7 μm or less, and even more preferably 5 μm or less. The average particle size of the small particles is even more preferably 500 nm or less. There is no particular limit to the lower limit of the average particle size, but from the viewpoint of the storage stability of the surface treatment solution, it is preferably about 5 nm or more, and more preferably 10 nm or more.

Furthermore, when the large particles and the small particles are mixed and the average particle size is measured, it is preferable that there are two peaks in the particle size distribution, i.e., each has a different peak value.

In addition to the difference in average particle size, the large particles and the small particles may have other differences. For example, the large particles preferably have a minimum film-forming temperature (MFT) of 70°C or more, while the small particles preferably have an MFT of less than 70°C. This MFT is the temperature required for the emulsion to form a film (film), and can be measured according to JIS K6828-2. Here, water-dispersible resins that do not form a film even at 70°C are considered to be included in water-dispersible resins with an MFT of 70°C or more.

More preferably, the MFT of the large particles is 100°C or higher and the MFT of the small particles is 50°C or lower, and since it is preferable for the small particles to be formed into a film at room temperature, it is even more preferable that the MFT is 40°C or lower.

In addition, the difference between the MFT of the large particles and the MFT of the small particles is preferably 30°C or more, more preferably 50°C or more, and even more preferably 100°C or more.

The molecular structures of the resins in the large and small particles may be the same, but may also be different.

As the large particles, it is also preferable to use composite organic particles with a core-shell structure, which are polymer complexes obtained by combining a polymer having an anionic functional group, such as a carboxy group or a sulfo group, with a polymer having a cationic functional group, such as an amino group or an amide group, and in which the core portion is an anionic polymer and the shell portion is a cationic polymer.

The anionic polymer of the composite organic particles may be, for example, a polymer containing (meth)acrylic acid as a repeating unit, more specifically, a styrene-(meth)acrylic acid copolymer. It may also contain a vinyl compound other than styrene and (meth)acrylic acid that is copolymerizable with these.

The cationic polymer (basic polymer) of the composite organic particles is, for example, a polymer containing a nitrogen-containing monomer, such as a homopolymer or copolymer containing a nitrogen heterocyclic compound such as N-vinylpyrrolidone, N-vinylcaprolactam, N-vinyloxazolidone, or N-vinylimidazole as a repeating unit. As the comonomer that forms the copolymer, for example, one or more of general vinyl compounds such as styrene, (meth)acrylic acid ester, vinyl acetate, or acrylamide can be selected and used.

In this case, the ratio of anionic polymer to cationic polymer is preferably 1 part anionic polymer to 3 to 10 parts cationic polymer by weight in order to make the charge on the particle surface cationic.

As commercially available products of such composite organic particles, "PP-15" and "PP-17" (both manufactured by Meisei Chemical Industry Co., Ltd.) can be preferably used.

The amount of water-dispersible resin in the surface treatment liquid (the total solid content of both large and small particles when large and small particles are used) is preferably 2% by weight or more, more preferably 3% by weight or more, and even more preferably 5% by weight or more, from the viewpoint of ink fixation on the substrate surface after treatment. On the other hand, if the viscosity of the treatment liquid is too high, uniform treatment becomes difficult, so the amount of resin is preferably 50% by weight or less, and more preferably 30% by weight or less.

The water contained in the surface treatment solution functions as a solvent, or vehicle, for the surface treatment solution, and tap water, ion-exchanged water, deionized water, etc. can be used. Water is a highly volatile solvent and evaporates easily after being discharged onto the substrate, preventing the voids in the substrate from being blocked after surface treatment and preventing the deterioration of the substrate's original properties after surface treatment, such as the hygroscopicity of wood. Water is also harmless and highly safe, and does not pose problems such as VOCs, making the surface-treated substrate environmentally friendly.

The higher the water content in the surface treatment solution, the lower the viscosity of the surface treatment solution and the easier it is to handle, so water is preferably 60% by weight or more of the total treatment solution, and more preferably 65% by weight or more.

The upper limit of the water content is not particularly limited, but in one embodiment in which the treatment liquid contains large and small particles of a water-dispersible resin, the water content is preferably 95% by weight or less, and more preferably 90% by weight or less. In another embodiment, the water content is preferably 85% by weight to 95% by weight.

The solvent of the surface treatment solution is preferably composed mostly of water, but may contain a water-soluble organic solvent in addition to water as necessary. As the water-soluble organic solvent, an organic compound that is liquid at room temperature and dissolves in water can be used, and it is preferable to use a water-soluble organic solvent that mixes uniformly with the same volume of water at 20°C under 1 atmosphere.

For example, lower alcohols such as methanol, ethanol, 1-propanol, isopropanol, 1-butanol, 2-butanol, isobutanol, and 2-methyl-2-propanol; glycols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, and polypropylene glycol; glycerins such as glycerin, diglycerin, triglycerin, and polyglycerin; acetins such as monoacetin, diacetin, and triacetin; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, and ethylene glycol monobutyl ether. , diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monopropyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, and other glycol ethers; triethanolamine, 1-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, β-thiodiglycol, sulfolane, and the like can be used. The boiling point of the water-soluble organic solvent is preferably 100°C or higher, and more preferably 150°C or higher.

These water-soluble organic solvents may be used alone, or two or more of them may be used in combination as long as they form a single phase with water. From the viewpoint of viscosity adjustment and moisturizing effect, the content of the water-soluble organic solvent is preferably 30% by weight or less in the treatment liquid (or 50% by weight or less in the solvent).

In addition, the surface treatment liquid preferably further contains a surface tension adjuster (surfactant) to reduce the surface tension so that it can be applied evenly to the surface of the non-combustible wood, and also to suppress aggregation of small water-dispersible resin particles (small particles) when the liquid contains such particles, thereby improving the storage stability of the liquid.

Surfactants are broadly classified into those whose hydrophilic portion is ionic (cationic, anionic, zwitterionic) and those whose hydrophilic portion is nonionic. In this embodiment, from the viewpoint of foaming of the surface treatment liquid, it is preferable to use a nonionic surfactant that is less likely to foam. In addition, either a low molecular weight or a high molecular weight (generally referring to a molecular weight of about 2000 or more) may be used, but it is preferable to use a high molecular weight surfactant. The HLB value of the surfactant is preferably about 5 to 20.

Examples of nonionic surfactants include ester-type surfactants such as glycerin fatty acid esters and fatty acid sorbitan esters, ether-type surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers and polyoxypropylene alkyl ethers, and ether ester-type surfactants such as polyoxyethylene sorbitan fatty acid esters.

In this embodiment, acetylene glycol surfactants and silicone surfactants can be preferably used.

Commercially available acetylene glycol surfactants include Surfynol 104E and 104H, which are acetylene glycols, Surfynol 420, 440, 465, and 485, which have a structure in which ethylene oxide is added to acetylene glycol (Air Products and Chemicals Co., Ltd.), Olfine E-1004, E-1010, E-1020, PD-002W, PD-004, EXP. 4001, EXP-4200, EXP-4123, and EXP-4300, which are acetylene glycols (Nissin Chemical Industry Co., Ltd.), Acetyleneol E00 and E00P, which are acetylene glycols, and Acetyleneol E40 and E100, which have a structure in which ethylene oxide is added to acetylene glycol (Kawaken Fine Chemicals Co., Ltd.).

Silicone-based surfactants have extremely high surface tension and contact angle reducing capabilities, so they can quickly diffuse the surface treatment liquid onto the surface of non-flammable wood, even if the surface is not hydrophilic. As a result, the functional components of the surface treatment liquid can be evenly fixed onto the surface of the non-flammable wood, so when printed, the ink is evenly fixed onto the treated area, resulting in a high-quality printed image with excellent color development.

Among silicone surfactants, polyether-modified silicone surfactants, alkyl-aralkyl co-modified silicone surfactants, and acrylic silicone surfactants are preferred. Of the commercially available products, the "Silface SAG Series" (Nissin Chemical Industry Co., Ltd.) is preferably used.

The surfactant may be any one of the silicone-based surfactants listed above, or multiple surfactants that are mutually compatible may be used in combination.

When a surfactant is used, the content in the surface treatment solution is preferably about 0.1% by weight or more, more preferably 0.3% by weight or more, and even more preferably 0.5% by weight or more, while the amount of surfactant is preferably about 5% by weight or less, more preferably 4% by weight or less, and even more preferably 3% by weight or less.

In addition to the above components, any known additives such as moisturizers, defoamers, pH adjusters, antioxidants, and preservatives may be added to the surface treatment solution, as long as they do not impair the function of the treatment solution. A combination of multiple types of these additives may also be used.

The surface treatment solution can be prepared by dispersing water, a cationic water-dispersible resin, a surface tension adjuster, and any optional additives, all at once or in portions, in a known dispersing machine such as a bead mill, and, if desired, passing the mixture through a known filtering machine such as a membrane filter.

In addition, when the surface treatment liquid contains large and small particles as cationic water-dispersible resins, the application of the surface treatment liquid can be carried out in two stages. That is, for example, a surface treatment liquid containing either large or small particles and a surface treatment liquid containing the remaining one can be prepared, and both can be applied to the non-combustible wood. When applying the large and small particles separately, it is preferable to apply the large particles first, since if the small particles are applied first, they will penetrate further into the voids in the non-combustible wood, and their effect as a binder for the ink may be weakened. Note that, when applying two types of surface treatment liquid as described above, the amount of surface treatment liquid is the total amount of the two types of surface treatment liquid.

Next, we will explain in detail the inks used in inkjet printing.

As mentioned above, the ink used in inkjet printing is not particularly limited, but is preferably a non-UV curable ink, and is preferably a water-based ink. In other words, it is preferably an ink that contains water, a binder resin, and a coloring material.

There are no particular limitations on the water, so long as it functions as a solvent, or vehicle, for the ink, and tap water, ion-exchanged water, deionized water, etc. can be used. As described above for the surface treatment liquid, water is safe and highly volatile, so it can prevent the original performance of the decorated non-combustible wood from being deteriorated.

The water content in the ink is preferably 30% by weight or more of the total amount of ink, more preferably 60% by weight or more, and even more preferably 65% by weight or more. The water content is preferably 95% by weight or less, and even more preferably 90% by weight or less.

The ink solvent is preferably composed mostly of water, but may contain water-soluble organic solvents in addition to water, if necessary. As the water-soluble organic solvent, one or more of the same solvents that can be used in the surface treatment liquid can be selected and used.

When two or more water-soluble organic solvents are used, the total content in the ink is preferably 5 to 50% by mass, and more preferably 10 to 35% by mass.

As the binder resin, a water-soluble resin or a hydrophilic resin can be used, and there is no particular limitation. In order to improve the water resistance of the obtained image, it is preferable to contain a water-dispersible resin, and the water-dispersible resin may be used in combination with a water-soluble resin.

Examples of water-soluble resins include polyvinyl alcohol, polyacrylic acid, neutralized polyacrylic acid, acrylic acid/maleic acid copolymer, acrylic acid/sulfonic acid copolymer, styrene/maleic acid copolymer, etc. These can be used alone or in combination of two or more types.

In the case of water-dispersible resins, it is preferable to use anionic resin particles with a negatively charged particle surface. This is a resin that can be dispersed in particulate form without dissolving in water to form an oil-in-water (O/W) emulsion. Like self-emulsifying resins, the resin may have an anionic functional group on the particle surface, or the resin may be surface-treated by attaching an anionic dispersant to the resin particle surface. The anionic functional group is typically a carboxy group or a sulfo group, and the anionic dispersant is an anionic surfactant. If the surface is anionic, a chemical interaction with the cationic water-dispersible resin in the surface treatment liquid is obtained, which results in stronger fixation of the coloring material and increased durability of the image.

The surface charge of the resin particles can be evaluated by measuring the zeta potential. Specifically, it is preferable that the absolute value of the zeta potential is 30 mV or more.

As for the type of resin, it is preferable to use a resin that forms a transparent coating film. In addition, when producing the ink, it can be blended as a resin emulsion.

Typical examples include ethylene-vinyl chloride copolymer resin, (meth)acrylic resin, styrene-maleic anhydride copolymer resin, urethane resin, vinyl acetate-(meth)acrylic copolymer resin, vinyl acetate-ethylene copolymer resin, and resin emulsions thereof, which can be used alone or in combination. Here, "(meth)acrylic resin" refers to both acrylic resin and methacrylic resin.

As mentioned above, these resins can be given a negative surface charge by introducing anionic functional groups or by surface treating them with anionic dispersants, etc.

Of these water-dispersible resins (or emulsions thereof), it is preferable to use urethane resins (emulsions) with a glass transition temperature (Tg) of -35 to 40°C from the standpoint of stable ejection performance from the inkjet head and adhesion to the substrate. Specific examples of such resin emulsions include Superflex 460, 420, 470, 460S (carbonate-based urethane resin emulsions, all trade names), 150HS (ester-ether-based urethane resin emulsion, trade name), 740, 840 (aromatic isocyanate-based ester-based urethane resin emulsion, all trade names) from Daiichi Kogyo Seiyaku Co., Ltd., and NeoRez R-9660, R-2170 (aliphatic polyester-based urethane resin emulsions, all trade names), NeoRez R-966, R-967, R-650 (aliphatic polyether-based urethane resin emulsions, all trade names), R-986, R-9603 (aliphatic polycarbonate, all trade names) from DSM.

From the viewpoint of stability in the ink, it is also preferable to use a (meth)acrylic resin or a (meth)acrylic resin copolymer. Specific examples include Mowinyl 966A, 6963, 6960 (acrylic resin emulsions, all trade names), 6969D, and RA-033A4 (styrene/acrylic resin emulsions, all trade names) from Japan Coating Resins Co., Ltd., Joncryl 7100, PDX-7370, and PDX-7341 (styrene/acrylic resin emulsions, all trade names) from BASF Corporation, and Boncoat EC-905EF, 5400EF, and CG-8400 (acrylic/styrene-based emulsions) from DIC Corporation.

The water-dispersible resin may be composed of a single type of resin (or an emulsion thereof) such as a urethane resin or an acrylic resin, or may be composed of a combination of multiple types of resins (or emulsions thereof).

The water-dispersible resin particles that form the emulsion may have any particle size suitable for inkjet printing, and generally, the average particle size (median size measured on a volume basis by dynamic light scattering) is preferably 300 nm or less, more preferably 250 nm or less, even more preferably 200 nm or less, and even more preferably 150 nm or less. There is no particular limit to the lower limit of the average particle size, but from the viewpoint of storage stability of the ink, it is preferably about 5 nm or more, and more preferably 10 nm or more.

The amount (solid content) of water-dispersible resin and/or water-soluble resin in the ink is preferably 1:0.5 to 1:7 (weight ratio) in terms of the ratio of colorant to resin (colorant:resin). By keeping the resin content within this range, it is possible to ensure sufficient water abrasion resistance and high image quality of the image printed on the surface of the substrate. If the ratio of resin to colorant is less than 0.5, the fixation of the pigment may be poor, and if it is more than 7, the viscosity may become high and the ink may not be able to be ejected from the ink ejecting head.

Either pigments or dyes can be used as coloring materials for the ink, and they may be used alone or in combination. From the standpoint of weather resistance and print density of the decorative image, it is preferable to use pigments as coloring materials.

The colorant content is preferably in the range of 0.01 to 20% by weight of the total ink. Furthermore, the colorant content is more preferably 0.1% by weight or more, even more preferably 0.5% by weight or more, even more preferably 1% by weight or more, and even more preferably 15% by weight or less, even more preferably 10% by weight or less, and even more preferably 8% by weight or less.

As the dye, those generally used in the technical field of printing can be used, and there is no particular limitation. Specific examples include basic dyes, acid dyes, direct dyes, soluble vat dyes, acid mordant dyes, mordant dyes, reactive dyes, vat dyes, sulfur dyes, etc., and among these, water-soluble dyes and those that become water-soluble by reduction or the like can be used. More specific examples include azo dyes, rhodamine dyes, methine dyes, azomethine dyes, xanthene dyes, quinone dyes, triphenylmethane dyes, diphenylmethane dyes, methylene blue, etc. These dyes may be used alone or in combination of two or more kinds.

As the pigment, organic pigments such as azo pigments, phthalocyanine pigments, polycyclic pigments, and dye lake pigments, as well as inorganic pigments can be used. As the azo pigments, soluble azo lake pigments, insoluble azo pigments, and condensed azo pigments can be used. As the phthalocyanine pigments, metal phthalocyanine pigments and metal-free phthalocyanine pigments can be used. As the polycyclic pigments, quinacridone pigments, perylene pigments, perinone pigments, isoindoline pigments, isoindolinone pigments, dioxazine pigments, thioindigo pigments, anthraquinone pigments, quinophthalone pigments, metal complex pigments, and diketopyrrolopyrrole (DPP) can be used. As the inorganic pigments, carbon black and titanium oxide can be used as representative examples. These pigments may be used alone or in combination of two or more.

In order to improve the dispersion of the pigment in the ink, a pigment dispersant can be added to the ink as necessary. The pigment dispersant that can be used is not particularly limited as long as it stably disperses the pigment in the solvent, but it is preferable to use a known pigment dispersant represented by a polymer dispersant or a surfactant having pigment dispersing ability. Specific examples of polymer dispersants include the Solsperse (trade name) series manufactured by Lubrizol Japan Co., Ltd., the Joncryl (trade name) series manufactured by Johnson Polymer Co., Ltd., the DISPERBYK series and the BYK series manufactured by BYK Co., Ltd. Specific examples of surfactants include anionic fatty acid salts, alkyl sulfates, alkyl ether sulfates, alkylbenzene sulfonates, etc., such as the Demol (trade name) series manufactured by Kao Corporation, and nonionic polyoxyalkylene alkyl ethers.

The content of the pigment dispersant is sufficient as long as it is an amount that can sufficiently disperse the pigment in the solvent, and can be set appropriately within a range of, for example, a weight ratio of 0.01 to 2 per 1 pigment.

A surface tension reducer (surfactant) can be added to the ink to reduce the surface tension of the ink, ensure ejection stability when introduced into an inkjet head, and allow the ink to quickly penetrate the substrate to be printed. As a surface tension reducer, a surfactant that also has the effect of suppressing aggregation of water-dispersible resin particles, for example, the same surfactant as that blended in the surface treatment liquid, can also be used. A surfactant that has both a pigment dispersion function and a surface tension reduction function may also be used.

The amount of surface tension reducing agent in the ink is preferably about 0.1% by weight or more, more preferably 0.3% by weight or more, and even more preferably 0.5% by weight or more. On the other hand, the amount of surface tension reducing agent is preferably about 5% by weight or less, more preferably 4% by weight or less, and even more preferably 3% by weight or less.

In addition to the above ingredients, other ingredients such as humectants, defoamers, pH adjusters, antioxidants, and preservatives can be added to the ink, as long as they do not adversely affect the properties of the ink.

The method for producing the ink is not particularly limited, and the ink can be produced by any known method. For example, the ink can be prepared by dispersing all the components in a known dispersing machine such as a bead mill, either all at once or in portions, and passing the mixture through a known filtering machine such as a membrane filter, if desired. For example, the ink can be prepared by first uniformly mixing all the water and coloring material to prepare a mixed liquid, dispersing the mixed liquid in a dispersing machine, and then adding the remaining components to the dispersion and passing the mixture through a filtering machine.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

As shown in Table 1, water was applied to non-combustible wood using application members 1 to 6 by contact application, and the amount of water applied immediately after application was measured to check for the presence or absence of efflorescence.

The coating method was as follows: first, each coating member 1 to 6 was immersed in water for 30 seconds, and then removed until no water was dripping. Next, when no water was dripping, a 2 kg weight was placed on each coating member for 10 seconds to squeeze each coating member 1 to 6.

After that, as shown in Figure 1, the non-combustible wood W was stood upright so that the coating surface S of the non-combustible wood was vertical, and each coating member 1-6 was pressed by hand against one side of the non-combustible wood in this state, and coating was performed at a coating speed of 300 mm/s. Then, a pressure gauge P (Aiko Engineering's "Digital Force Gauge CPU GAUGE 9500 Series") was placed on the other side of the non-combustible wood to measure the pressure. Since non-combustible wood is made of a hard material that does not deform, measuring the pressure as described above indirectly measured the pressure with which each coating member 1-6 was pressed against the coating surface of the non-combustible wood.

The amount of coating was controlled by setting the pressure to 5 kPa, 10 kPa, 20 kPa, and 40 kPa. The relationship between the amount of coating and the occurrence of efflorescence is shown in Table 1.

The non-combustible wood used was manufactured by ARS Co., Ltd., and its dimensions were 300 mm in length x 600 mm in width x 50 mm in thickness.

The material of the coating member shown below was used, and its size was 70 mm length x 70 mm width x 30 mm thickness. Coating was performed by pressing the 70 mm length x 70 mm width surface against the coating surface of the non-combustible wood.
Application part 1: Sponge cloth (material: cellulose)
Application member 2: urethane sponge A
Application member 3: urethane sponge B
Coating member 4: urethane sponge C
Application member 5: Melamine sponge Application member 6: PVA (polyvinyl alcohol) sponge

The amount of water applied was calculated by subtracting the weight of the fireproof wood immediately after the water application from the weight of the fireproof wood before the application, and dividing the subtracted value by the area of the applied surface. Note that a coating amount of 0.0 g/ ^m2 does not mean that no water was applied at all, but that the coating amount was less than 0.1 g/ ^m2 .

The presence or absence of efflorescence was visually observed. As can be seen from Examples 1 to 6, efflorescence occurred when the coating amount exceeded 50 g/ ^m2 . Although not shown as an example, it was confirmed that efflorescence did not occur up to a coating amount of 50 g/ ^m2 .

In addition, in Examples 1 to 6 shown in Table 1, non-combustible wood made by ARS Co., Ltd. is used as the non-combustible wood, but it was confirmed that efflorescence occurs with other non-combustible wood when the amount of water applied exceeds 50 g/ ^m2 , and does not occur up to an application amount of 50 g/ ^m2 . The results are shown in Table 2. As shown in Table 2, the efflorescence phenomenon was confirmed for non-combustible wood made by Sakawa Co., Ltd. (product name: efflorescence-less non-combustible wood) and non-combustible wood made by Yoshida Lumber Co., Ltd. (product name: Fukufunen) as non-combustible wood. Except for the non-combustible wood, the conditions such as the water application method are the same as those in Example 1. In addition, the non-combustible agent for the non-combustible wood made by ARS Co., Ltd. and Yoshida Lumber Co., Ltd. in Example 1 is a boric acid-based agent, and the non-combustible agent for the non-combustible wood made by Sakawa Co., Ltd. is a special phosphoric acid-based agent, and all the base wood is cedar.

As shown in the "Water" column in Table 2, it was found that even with non-combustible wood manufactured by Sakawa Corporation and non-combustible wood manufactured by Yoshida Lumber Co., Ltd., efflorescence occurred when the amount of water applied exceeded 50 g/ ^m2 , but no efflorescence occurred up to an application amount of 50 g/ ^m2 .

In addition, in the above Examples 1 to 6, water was used as a substitute for the surface treatment liquid, but it was confirmed that the presence or absence of efflorescence depending on the amount of application when water was used was the same as the presence or absence of efflorescence depending on the amount of application when the above-mentioned surface treatment liquid (for example, a surface treatment liquid containing water, a cationic water-dispersible resin, and a surface tension adjuster, in which the cationic water-dispersible resin is large particles with a median diameter of 1 μm to 10 μm and small particles less than 1 μm as measured by dynamic light scattering) was used. The column "Surface treatment liquid" in Table 2 shows the evaluation results for the surface treatment liquid. As shown in Table 2, the presence or absence of efflorescence depending on the amount of application of water and the presence or absence of efflorescence depending on the amount of application of the above-mentioned surface treatment liquid were compared for the noncombustible wood of ARS Co., Ltd. in Example 1, the noncombustible wood of Sakawa Co., Ltd., and the noncombustible wood of Yoshida Lumber Co., Ltd. The application conditions for water and surface treatment liquid (type of application member, method of squeezing the application member, application speed) were the same as in Example 1, and the pressure of the application member was 10 kPa.

Specifically, the surface treatment solution used in the evaluations in Table 2 below was obtained by premixing the components shown in Table 3 below in the ratios shown in Table 3, and then dispersing the mixture with a homogenizer for one minute.

Details of the raw materials listed in Table 3 below are as follows:
"PP-15": Meisei Chemical Industry Co., Ltd., cationic water-dispersible composite organic particles (average particle size: about 1.8 μm, does not form a film at 100° C.)
"Polysol AE-803" is a cationic water-based acrylic resin emulsion (average particle size 419 nm, MFT 0°C) manufactured by Showa Denko K.K.
"Silface SAG503A": manufactured by Nissin Chemical Industry Co., Ltd., a silicone-based surfactant "Olfine E1010": manufactured by Nissin Chemical Industry Co., Ltd., an acetylene glycol-based surfactant

The average particle size of the resin is the volume-based median diameter measured at a temperature of 25° C. using a dynamic light scattering particle size distribution measuring device "Nano Prtica SZ-100 Nanoparticle Analyzer" (manufactured by HORIBA, Ltd.) by diluting each resin dispersion with purified water to a particle concentration of 0.5% by mass, setting the dispersion medium refractive index to 1.333, the sample refractive index to 1.600, and the dispersion form to "polydisperse" and "narrow."
As shown in Table 2 above, it was found that even when a surface treatment liquid was applied to non-combustible wood, efflorescence occurred when the amount applied was more than 50 g/ ^m2 , and no efflorescence occurred when the amount applied was less than 50 g/ ^m2 . In other words, it was found that the results were the same as when water was used instead of the surface treatment liquid. This shows that water has a large influence on the efflorescence of non-combustible wood, and that components other than water in the surface treatment liquid have no effect on the efflorescence. In other words, it is believed that similar results can be obtained with other surface treatment liquids as long as they contain water.

In the above description of the examples, it was confirmed that the amount of the surface treatment liquid applied must be 50 g/ ^m2 or less in order to suppress the efflorescence phenomenon of non-combustible wood, but in order to ensure the image quality of the printed image, the amount of the surface treatment liquid applied is preferably 7 g/m2 or ^more as described above, and more preferably 10 g/m2 or ^more . Table 4 shows the results of confirming the lower limit of the amount of the surface treatment liquid applied. Note that non-combustible wood manufactured by ARS Co., Ltd. was used, the application conditions of the surface treatment liquid (type of application member, squeezing method of application member, application speed) were the same as in Example 1, and the pressure of the application member was 10 kPa. After the surface treatment liquid was applied, it was dried overnight, and the image quality was evaluated by inkjet printing. For the ink used in the evaluation of Table 4, each component listed in Table 5 was premixed in the ratio (solid content equivalent) listed in Table 5, and the resulting dispersion was passed through a membrane filter with a pore size of 3 μm to obtain an aqueous ink set consisting of four colors (cyan, magenta, yellow and black).

Details of the raw materials listed in Table 5 are as follows.
"CAB-O-JET 250C": manufactured by Cabot Corporation, water-based self-dispersed cyan pigment dispersion "CAB-O-JET 260M": manufactured by Cabot Corporation, water-based self-dispersed magenta pigment dispersion "CAB-O-JET 270": manufactured by Cabot Corporation, water-based self-dispersed yellow pigment dispersion "CAB-O-JET 200": manufactured by Cabot Corporation, water-based self-dispersed black pigment dispersion "Takelac W-5661": manufactured by Mitsui Chemicals, Inc., urethane resin emulsion "Surfynol 465": manufactured by Nissin Chemical Industry Co., Ltd., acetylene glycol surfactant

Image quality was evaluated in terms of reproducibility of wood grain images, reproducibility of gradation images, color development, and bleeding.

Regarding the reproducibility of wood grain images, a wood grain image was printed on non-combustible wood and the reproducibility of the wood grain image was visually confirmed. If the wood grain pattern was reproduced comparable to real wood, it was rated as "A", if it was inferior to "A" but the wood grain pattern was reproduced, it was rated as "B", and if the wood grain pattern could not be reproduced, it was rated as "C".

To check the reproducibility of the gradation image, a full-color gradation image was printed on non-combustible wood and the reproducibility was checked visually. If the gradation was well reproduced, it was rated as "A", and if the gradation could not be reproduced, it was rated as "C".

Regarding color development, solid images of C (cyan), M (magenta), Y (yellow) and K (black) were printed on non-combustible wood and the color development was visually confirmed. It was confirmed whether the color development was equivalent to that of inkjet paper. If the color development was equivalent to that of inkjet paper, it was rated as "A." If the color development was inferior to "A" but was close to that of inkjet paper and had sufficient color development for practical use, it was rated as "B." If the color development was not as good as that of inkjet paper and was dull, it was rated as "C."

Regarding bleeding, a 0.3 mm thin line was printed on non-combustible wood, and the degree of bleeding of the thin line was visually confirmed. A rating of "A" was given to cases where there was absolutely no bleeding, smearing, or cutting, a rating of "B" was given to cases where there was bleeding, smearing, or cutting but at a level that was not noticeable, and a rating of "C" was given to cases where the thin line had bled significantly and could not be reproduced.

From the results shown in Table 4, it was found that the coating amount of the surface treatment liquid is preferably 7 g/m2 or ^more , as described above, and more preferably 10 g/ ^m2 or more.

Next, the relationship between the water absorption, water retention, and deformation of the applicator, as well as the pressure applied to the non-combustible wood, and the uniformity of application of the surface treatment liquid on the non-combustible wood was evaluated. In addition to the applicator members 1 to 6 used in the above-mentioned Examples 1 to 6, applicator member 7 (urethane sponge D) was used as the applicator member. Table 6 shows the physical properties (water absorption, water retention, and deformation) of applicator members 1 to 7.

Water absorption is an index showing the amount of surface treatment liquid that a coating member can absorb and retain inside per unit volume. Water absorption was calculated by immersing each coating member in water for 30 seconds, removing it, measuring its weight when no more water was dripping, and dividing the measured weight by the volume of each coating member.

The water retention capacity was calculated by squeezing each of the coating members 1 to 7 by placing a 2 kg weight on each coating member for 10 seconds after there was no more water dripping in the above-mentioned water absorbency evaluation, measuring the weight immediately after squeezing, and dividing the measured weight by the volume of each coating member 1 to 7.

The amount of deformation was measured by pressing a pressure gauge (Aiko Engineering's "Digital Force Gauge CPU GAUGE 9500 Series" pressure gauge) against the surface of each coating member 1 to 7, and measuring the depth from the surface before deformation of the most deformed area when the pressure reached 30 kPa.

The coating method was the same as that described in the evaluation of the coating amount described above. As for the uniform coating property, it was confirmed that the uniform coating property when water was used was the same as that when the above-mentioned surface treatment liquid was used, as in the evaluation of the coating amount.
The amount of the surface treatment liquid (water) was 35 g/ ^m2 , and it was confirmed that no efflorescence occurred in any of the examples shown below.

Table 7 shows the evaluation results of the coating uniformity of the surface treatment liquid when the pressure of application against the non-combustible wood was changed using application members 1 to 6. The pressures when each of application members 1 to 6 was pressed against the non-combustible wood were 3 kPa, 5 kPa, 10 kPa, 20 kPa, and 40 kPa. The evaluation of the uniformity of application was performed visually, with an "A" being given to a case where the coating was uniform, a "B" being given to a case where there was some coating unevenness, and a "C" being given to a case where there was noticeable coating unevenness. The evaluation results of the uniformity of application for each of application members 1 to 6 are shown in Table 7.

The evaluation results for Examples 7 to 19 shown in Table 7 indicate that it is preferable to press the application member against the non-combustible wood with a pressure of 5 kPa or more.

Next, Table 8 shows the relationship between the water absorption and the coating uniformity of the surface treatment liquid of the coating members 1 to 7. The pressures with which the coating members 1 to 7 were pressed against the non-combustible wood were as shown in Table 8.

From the evaluation results of Examples 20 to 34 shown in Table 8, it was found that the water absorbency of the applying member is preferably 0.44 g/cm ³ or more.

Next, Table 9 shows the relationship between the deformation amount and the coating uniformity of the surface treatment liquid of the coating members 1 to 7. The pressures with which the coating members 1 to 7 were pressed against the non-combustible wood were as shown in Table 9.

The evaluation results for Examples 35 to 47 shown in Table 9 indicate that it is preferable for the deformation amount of the application member to be 25 mm or less.

Next, Table 10 below shows the evaluation results of the image quality of the printed image when the surface treatment liquid was applied to non-combustible wood using a contact application method, and the evaluation results of the image quality of the printed image when the surface treatment liquid was applied using a non-contact (spray) application method.

In Examples 48 to 50, the surface treatment liquid was applied by a contact application method, and in Examples 51 to 52 and Comparative Example 1, the surface treatment liquid was applied by a spray application method.

In Table 5, Non-combustible Wood 1 is non-combustible wood made of cedar wood manufactured by ARS Co., Ltd., similar to Example 1 described above, and Non-combustible Wood 2 is non-combustible wood made of cypress wood manufactured by ARS Co., Ltd. The dynamic contact angles of the surface treatment liquid with respect to the non-combustible wood in Examples 7 to 11 and Comparative Example 2 are as shown in Table 5. The dynamic contact angle was measured one second after the surface treatment liquid hit the non-combustible wood.

The applicator in Examples 48 and 49 was the same as in Example 1, and the surface treatment liquid was applied to the non-combustible wood using the same application method as in Example 1. The pressure of the applicator on the non-combustible wood was 10 kPa. In Example 50, a sponge brush was used as the applicator. In Example 50, the tip of the sponge brush was immersed in the surface treatment liquid, and the tip was pressed vertically three times against an absorbent material such as Kimtowel (registered trademark) until no drips remained. The application speed was 300 mm/S, and the pressure of the applicator on the non-combustible wood was 10 kPa.

In Examples 51 to 52 and Comparative Example 1, the surface treatment liquid was applied to the non-combustible wood using a spray. The spray used was a WAGNER W550 manufactured by Wagner Spraytec Japan Co., Ltd. The surface treatment liquid was applied to the non-combustible wood while moving the spray at approximately 1 m/sec.

The coating amount of the surface treatment liquid was 10.0 g/ ^m2 in Examples 48 to 51, 35.0 g/ ^m2 in Example 52, and 70.0 g/ ^m2 in Comparative Example 1.

In addition to the four image qualities (reproducibility of wood grain image, reproducibility of gradation image, color development, and bleeding) mentioned above, the surface properties of the substrate after the application of the surface treatment liquid were also evaluated in Table 10. Regarding the surface properties of the substrate, the non-combustible wood after the application of the surface treatment liquid was visually inspected to see whether the wood grain pattern remained with the same texture as the non-combustible wood without the surface treatment liquid. The evaluation was given as "A" when the wood grain pattern was clearly visible and there was no unnatural glossiness, "B" when there was something wrong with either the clarity or glossiness of the wood grain pattern or the color of the non-combustible wood surface was slightly discolored (white, yellowing), and "C" when there was something wrong with both the clarity and glossiness of the wood grain pattern or the non-combustible wood surface was clearly discolored.

Table 10 also shows the results of checking whether or not efflorescence occurred for Examples 48 to 52 and Comparative Example 1.

As shown in Table 10 above, when the surface treatment liquid was applied using a contact application method, all evaluations of the substrate surface properties and image quality were "A", but when the surface treatment liquid was applied using a non-contact (spray) application method, it was found that the image quality deteriorated. This is thought to be because the surface treatment liquid was repelled by the surface of the non-combustible wood and was not applied evenly. On the other hand, when the surface treatment liquid was applied using a contact application method, even when the dynamic contact angle was as high as 28.3° as in Examples 48 and 50, the surface treatment liquid could be applied evenly and high image quality was confirmed. Furthermore, as shown in Example 49, it was confirmed that image quality could be ensured when the dynamic contact angle of the surface treatment liquid with respect to the non-combustible wood was 10° or more.

The following supplementary notes are further disclosed regarding the method for producing a decorative article made of non-combustible wood, the decorated article, the method for producing a surface-treated article made of non-combustible wood, and the surface-treated article of the present invention.
(Additional Note)

In the manufacturing method of the non-combustible wood decorative article of the present invention, the surface treatment liquid can be applied by a contact application method in the surface treatment liquid application step.

In addition, in the manufacturing method of a decorative article made of non-combustible wood according to the present invention, the dynamic contact angle of the surface treatment liquid with respect to the non-combustible wood can be set to 10° or more.

In the method for producing a decorative article made of noncombustible wood according to the present invention, it is preferable that the surface treatment liquid is applied using an application member having a water absorbency of 0.44 g/cm ³ or more in the surface treatment liquid application step.

In addition, in the manufacturing method of the non-combustible wood decorative article of the present invention, in the surface treatment liquid application step, it is preferable to apply the surface treatment liquid using an application member that has a deformation amount of 25 mm or less when pressed with a pressure of 30 kPa.

In addition, in the method for manufacturing a decorative article made of non-combustible wood according to the present invention, in the surface treatment liquid application step, it is preferable to apply the surface treatment liquid by pressing an application member against the non-combustible wood with a pressure of 5 kPa or more.

In the method for manufacturing a decorative article made of noncombustible wood according to the present invention, the amount of the surface treatment liquid applied to the noncombustible wood in the surface treatment liquid application step can be 7 g/m ² or more.

The decorative article of the present invention comprises fireproof wood that has been subjected to a fireproofing treatment, a surface treatment layer formed on the surface of the fireproof wood using a surface treatment liquid containing at least water, a colorant fixing component and a surface tension adjuster, and an inkjet printing layer formed on the surface treatment layer, wherein the surface treatment layer is formed with an application amount of the surface treatment liquid on the fireproof wood of 50 g/m2 ^or less.

The method for producing a surface-treated non-combustible wood article of the present invention includes a surface treatment liquid application step of applying a surface treatment liquid containing at least water, a colorant fixing component, and a surface tension adjuster to non-combustible wood that has been subjected to a fireproofing treatment, and the amount of the surface treatment liquid applied to the non-combustible wood in the surface treatment liquid application step is 50 g/ ^m2 or less.

The surface-treated non-combustible wood article of the present invention comprises non-combustible wood that has been subjected to a fire-retardant treatment, and a surface treatment layer formed on the surface of the non-combustible wood using a surface treatment liquid containing at least water, a colorant fixing component and a surface tension adjuster, and the surface treatment layer is formed with an application amount of the surface treatment liquid on the non-combustible wood of 50 g/m2 ^or less.

W Non-combustible wood S Coating surface P Pressure gauge

Claims (10)

The method includes a surface treatment liquid application step of applying a surface treatment liquid containing at least water, a colorant fixing component, and a surface tension adjusting agent to non-combustible wood obtained by subjecting wood to a fireproofing treatment, and a printing step of performing inkjet printing on the non-combustible wood to which the surface treatment liquid has been applied,
A method for manufacturing a decorative article made of non-combustible wood, wherein the amount of the surface treatment liquid applied to the non-combustible wood in the surface treatment liquid application step is 50 g/m2 or ^less . The method for manufacturing a decorative article made of non-combustible wood according to claim 1, wherein the surface treatment liquid is applied by a contact application method in the surface treatment liquid application step. The method for manufacturing a decorative article made of non-combustible wood according to claim 2, wherein the dynamic contact angle of the surface treatment liquid with respect to the non-combustible wood is 10° or more. 4. The method for manufacturing a decorative article made of noncombustible wood according to claim 2, wherein in the surface treatment liquid application step, the surface treatment liquid is applied using an application member having a water absorption of 0.44 g/cm ³ or more. A method for manufacturing a decorative article made of non-combustible wood according to any one of claims 2 to 4, in which the surface treatment liquid is applied using an application member that has a deformation amount of 25 mm or less when pressed with a pressure of 30 kPa in the surface treatment liquid application process. The method for manufacturing a decorative article made of non-combustible wood according to any one of claims 2 to 5, wherein in the surface treatment liquid application step, the surface treatment liquid is applied by pressing an application member against the non-combustible wood with a pressure of 5 kPa or more. 7. The method for manufacturing a decorative article made of non-combustible wood according to claim 1, wherein the amount of the surface treatment liquid applied to the non-combustible wood in the surface treatment liquid application step is 7 g/m2 or ^more . Non-combustible wood that has been treated to be non-combustible;
a surface treatment layer formed on the surface of the fireproof wood using a surface treatment liquid containing at least water, a colorant fixing component, and a surface tension adjusting agent;
an inkjet printing layer formed on the surface treatment layer,
A decorative article in which the surface treatment layer is formed by applying the surface treatment liquid to the noncombustible wood in an amount of 50 g/m2 ^or less. The method includes a surface treatment liquid application step of applying a surface treatment liquid containing at least water, a colorant fixing component, and a surface tension adjuster to the fireproof wood obtained by subjecting the wood to a fireproof treatment,
A method for producing a surface-treated non-combustible wood article, wherein the amount of surface treatment liquid applied to the non-combustible wood in the surface treatment liquid application step is 50 g/m2 or ^less . Non-combustible wood that has been treated to be non-combustible;
a surface treatment layer formed on the surface of the fireproof wood using a surface treatment liquid containing at least water, a colorant fixing component, and a surface tension adjusting agent;
A surface-treated non-combustible wood product, in which the surface treatment layer is formed by applying the surface treatment liquid to the non-combustible wood in an amount of 50 g/m2 or ^less .