JP2000303670A - Antibacterial wood plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an antibacterial wood plate which does not impair components thereof and does not adversely affect a human body, by forming a surface coating film containing a photocatalytic material, on a surface of the wood plate via a substrate film which is inert with respect to the photocatalytic material. SOLUTION: Fine particles comprising an inorganic compound and an inorganic salt are mixed into silicone or fluororesin, and the resultant mixture is applied to a surface of a wood plate. Then, the mixture is hardened at room temperature or at a temperature of 200 deg.C or less, to thereby form a transparent and thin substrate film which is inert with respect to a photocatalytic material. Next, the silicone or the fluororesin is dissolved or dispersed in a solvent, or made into a water-dispersed emulsion, to which the photocatalytic material is added, to thereby obtain a paint. The thus obtained paint is applied to the substrate film, which is heated at room temperature or at a temperature 200 deg.C or less, followed by conducting addition condensation and hardening, to thereby form an antibacterial wood plate. By interposing the substrate film, decomposition of cellulose, lignin, grease, resins, etc., by the photocatalytic material can be prevented, and therefore good appearance and touch of the wood plate can be maintained, to thereby obtain the wood plate which does not adversely affect a human body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wood board provided with antibacterial and antifungal properties, and more particularly to a wood floor board.

[0002]

2. Description of the Related Art Formaldehyde, such as urea resin, melamine resin, phenol resin, etc., is used as a laminated plywood or as a bonding material between wooden boards for a wooden board in a building or the like, for example, a wooden floorboard. However, free formaldehyde remains after curing, which gradually evaporates, affecting the human body and impairing health.

On the other hand, there have been attempts to reduce the above-mentioned free formaldehyde and to use an adhesive which does not require formaldehyde. However, by reducing or eliminating formaldehyde having an antibacterial and antifungal effect, bacteria, There is also a contradiction that damage caused by molds and the like also increases.

[0004] There is also a means of applying a paint containing an antibacterial metal such as silver on a wooden board. However, the appearance of woodgrain is easily impaired, and there is a concern that the metal may affect infants and the like.

It is generally known to form a film containing a photocatalytic substance such as titanium oxide directly on a substrate, and to activate the photocatalytic substance to perform antibacterial and antifungal treatment.

For example, Japanese Patent Application Laid-Open No. 10-130540 discloses a powder coating material for forming a lower coating film and an upper coating film on an object to be coated. Regarding powder coating containing powder, or JP-A-10-225640, photocatalyst particles are formed on a substrate via an inorganic binder, a silicone polymer, or a hardly decomposable binder such as a fluoropolymer. Further, JP-A-10-314596 discloses a coating composition comprising a water-dispersed emulsion containing a silicone resin containing photocatalyst particles, and forming a hydrophilic film by ultraviolet irradiation. Although disclosed, the object to be coated is not intended for a wooden board, and the present invention differs from the disclosed examples in the purpose, problems, and means of solution.

Japanese Patent Application Laid-Open No. Hei 10-329261 discloses that a polymer material is used as a base material, and the outermost layer is made of an inorganic material thin film layer having a photocatalytic function, and a photocatalytic function is provided between the polymer material and the inorganic material thin film layer. It is disclosed that an inorganic thin film layer having no inorganic thin film layer is provided and that the inorganic thin film layer is a vapor-deposited film.

[0008]

Since the outermost inorganic thin film layer is made of an inorganic substance although it is a thin film, when this is used for a wooden board, the soft feel of the wooden board is impaired. . Therefore, the formation of the inorganic substance thin film layer as the outermost layer is not appropriate. Of course, if the inorganic substance thin film layer is not transparent, the aesthetics inherent to the wooden board will be impaired.

The present invention is not limited to the above-mentioned wood board using the adhesive, but widely imparts antibacterial and antifungal properties to the wood board, without impairing the aesthetic appearance and soft feel of the wood board, and applying it to the human body and the like. It is an object of the present invention to provide a wooden board having no influence.

[0010]

SUMMARY OF THE INVENTION The present invention relates to an antibacterial wood board having a transparent surface coating containing a photocatalytic substance formed on a wood board, wherein a transparent coating is provided between the wood board and the surface coating. This is an antibacterial wood board with a base coat inactive against photocatalytic substances.

It is preferable that the surface coating film mainly contains a silicone resin or a fluorine-containing resin.

It is preferable that the base film is a coating film mainly containing a silicone resin or a fluorine-containing resin, or a transparent inorganic oxide film formed by physical or chemical vapor deposition.

[0013]

DETAILED DESCRIPTION OF THE INVENTION As a photocatalytic substance, titanium oxide, particularly anatase type titanium oxide, has high photocatalytic activity,
preferable. In promoting the activation of the photocatalyst, a known cocatalyst such as nickel oxide or ruthenium oxide can be used in combination, but one that impairs the transparency should be avoided.

In forming a transparent surface coating film containing a photocatalytic substance, a silicone resin or a fluorine-containing resin is employed as a binder component. These resins are hardly attacked by a photocatalytic substance as seen in known examples.

That is, a silicone resin or a fluorine-containing resin is dissolved or dispersed in a solvent, or is made into a water-dispersible emulsion, and a photocatalyst substance or a cocatalyst is added thereto to form a paint. Photocatalytic substance is resin content 100
For example, 50 to 150 parts by weight is added to the parts by weight. The co-catalyst is appropriately added within a range that does not impair the transparency of the coating film.

For example, in the case of a silicone resin, an initial condensate such as monosilanol, disilanol, trisilanol or the like having an ethyl, methyl, phenyl group or the like is dissolved in an aromatic solvent or the like, and an organic metal salt, metal or the like is dissolved. An amount of a curing agent and a photocatalytic substance are added, and the mixture is polycondensed and cured by heating. In addition, you may co-condense or make it compatible with phenol resin, amide resin, etc. In the case of a fluorine-containing resin, a dispersion type in which ethylene trifluoride, ethylene tetrafluoride, etc. is dispersed in water or an organic solvent in a sol state, and a photocatalyst substance is added thereto to form a paint, which undergoes addition polymerization and curing by heating Let it. If the adhesion to the object is not good,
It is a known technique to form an intervening film of an adhesiveness improving agent such as a silane coupling agent on an object to be coated in advance, or to mix an adhesiveness improving agent into a resin solution.

These paints are applied onto the undercoat by known coating means such as brush coating, flow coating, roller coating, spray coating, screen printing and the like, and cured at a room temperature to a relatively low temperature of about 200 ° C. or less. Is good. Although the thickness of the coating film is not limited, it is about several hundred nm to several tens μm. If the thickness is smaller than the above range, the amount of the photocatalyst substance tends to be insufficient, and it is difficult to exert remarkable effects on antibacterial and antifungal.

The transparent base film is formed so that the photocatalytic substance does not come into direct contact with the wooden board, and the same silicone resin or fluorine-containing resin as described above can be used as it is. Alternatively, fine particles made of a non-colored inorganic compound or inorganic salt, such as silica, alumina, magnesia, calcite (calcium carbonate), magnesium carbonate, zeolite, and pyrophyllite, may be mixed into a silicone resin or a fluorine-containing resin. Good.

This is applied by a known coating means such as brush coating, flow coating, roller coating, spray coating, screen printing and the like, and is preferably cured at a room temperature to a relatively low temperature of about 200 ° C. or less. As described above, since the base film is provided so that the photocatalytic substance does not come into direct contact with the wooden board, the thickness of the coating film may be thin, for example, about several nm to several μm.

Alternatively, a transparent inorganic oxide film may be formed on the base film by physical or chemical vapor deposition. For example, means for forming a film of silica, alumina, magnesia, zirconia, etc. by a sputtering method may be used. It is valid.

[0021]

EXAMPLES As a veneer bonded plate, one using a conventional phenolic resin-formaldehyde adhesive and one using a casein-based adhesive were prepared. Further, in each of the above two examples, a product in which a surface coating film / base film containing a photocatalytic substance was formed was prepared, and those in which no film was formed were compared with each other.
The test described later was performed.

[Preparation of 5-Layer Plywood with Veneer] Size 20cm ×
Wooden board with thickness of 80mm and thickness of 0.2mm, and same size with thickness of 0.1mm
Were prepared, and the following samples were prepared for these.

Sample: An adhesive liquid composed of phenol resin-formaldehyde (+ alkaline catalyst) was applied to a wooden plate and a veneer as in the prior art, and heated and cured to obtain a five-layer plywood having a veneer adhered to the uppermost layer.

Sample: In place of the phenolic resin-based adhesive, a casein-based adhesive was used, applied to a wooden plate and a veneer, and heated and cured to obtain a five-layer plywood having a veneer adhered to the uppermost layer.

[Formation of Photocatalyst Layer] Sample: Based on the configuration of the sample,
Silicone resin varnish (toluene solution based on (CH ₃ ) ₂ Si (OH) ₂ ), 100 parts by weight of resin, 5 parts of quartz powder
The paint to which 0 parts by weight has been added is brush-coated, dried by applying hot air at 150 ° C. to form a base coat having a coat thickness of 500 nm, and further, in a silicone resin varnish similar to the above, a resin content of 100 parts by weight. A brush containing 80 parts by weight of anatase-type titanium oxide was applied to the coating, dried by applying hot air at 150 ° C., and the coating thickness was 10 μm.
Was formed.

Sample: Separately, based on the structure of the sample, a fluororesin varnish (water dispersion of ethylene tetrafluoride) was placed on the upper surface of the veneer, and alumina powder
0 parts by weight of the paint is brush-coated as a base layer, and 150
C. and dried with hot air at a temperature of 500 ° C. to form a base coat having a thickness of 500 nm.
A paint in which 80 parts by weight of anatase-type titanium oxide was added to 0 parts by weight was brush-coated, and dried by blowing hot air at 150 ° C. to form a surface coat having a coat thickness of 10 μm.

Specimen: Based on the constitution of the specimen, a silica film having a thickness of 80 nm was formed on the upper surface of the veneer by sputtering, and a silicone resin varnish ((CH ₃ ) ₂ Si (O
H) Toluene solution based on ₂ ), 100 parts by weight of resin, 80 parts by weight of anatase-type titanium oxide was brush-painted, and dried by applying hot air at 150 ° C. to a film thickness of 10 μm. Was formed.

[Preliminary observation]
, When compared with a sample without a coating film, the wood pattern was clearly observed, although the color density was slightly light.
It was also found that it had a soft tactile sensation, and that the woody characteristics were fully utilized.

[Ultraviolet exposure test]
, And each sample was laid on a veneer surface or a coating film surface side in a wooden box having an inner wall front and rear width of 20 cm × length 80 cm × height 50 cm. The upper lid of the box has been removed.

About 1 m above each box, a rod-shaped fluorescent lamp having a length of about 1 m and a capacity of 20 kW was suspended in parallel with the box, and the upper surface of each sample was irradiated with light.

After preparing as described above, 1 ml of a previously cultured suspension of blue mold was placed approximately 5 cm in the center of each sample.
, And the fluorescent lamp was turned on continuously for two weeks at a temperature of 25 to 30 ° C and a relative humidity of 70 to 90%, and left as it was.

Incidentally, some of the samples were stored in a dark room free from the influence of ultraviolet rays so as to be compared with test samples exposed to ultraviolet rays (fluorescent lamps).

[Antifungal test] The propagation of the mold on each plywood sample was observed under a mirror for the two-week-old samples. No growth of mold was observed for the sample and
Alternatively, it was observed that the spread area of the mold was reduced.
On the other hand, in the sample, it was observed that the mold was clearly growing. That is, a sample having a photocatalyst layer
Has a fungicidal property similar to that of a sample having no photocatalytic layer due to phenolic resin adhesion, and also has an antibacterial effect.

Further, the sample does not have a formalin smell, and it is presumed that the photocatalytic substance in the coating can also decompose and render formaldehyde harmless.

[Observation test] The film-formed sample was observed under a magnifying glass in comparison with the sample not exposed to ultraviolet light, but no signs or abnormalities were observed, which also caused deterioration of the plywood.

The sample was further exposed to ultraviolet light for a further 4 weeks, and then compared with a sample not exposed to ultraviolet light as described above. Observation was also made, but no signs or abnormalities were found to cause deterioration of the plywood. Did not.

[0037]

According to the present invention, celluloses, lignin, fats, resins, etc., which are easily decomposed by the photocatalytic substance, do not come into direct contact with the photocatalytic substance.
An effect of imparting antifungal properties and obtaining a wooden board (processed product) without impairing the beauty and soft feel of the wooden board and without affecting the human body can be obtained.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09D 127/12 C09D 127/12 183/04 183/04 F term (Reference) 2B250 AA05 BA08 CA11 DA04 EA02 EA13 FA31 FA33 FA37 FA46 FA53 4F100 AA17C AA19 AA20 AA21 AK17B AK17C AK18 AK52B AK52C AP00A AP01 AP02 AT00A BA03 BA07 BA10B CA30B CB02 CC00B CC00C DE01 EH66C GB08 JC00 JL08B JN01B JN01C JN02C 4G069 AA03 AA08 BA04B BA22A BA22B BA29A BA48A CA01 CA11 EC22Y FA02 FB23 4J038 CD091 DL031 EA011 KA04 PC06

Claims (3)

[Claims] An antibacterial wood board having a transparent surface coating containing a photocatalytic substance formed on a wood board, wherein a transparent and inert to the photocatalytic substance is provided between the wood board and the surface coating. An antibacterial wooden board characterized by interposing a base film. 2. The antibacterial wood board according to claim 1, wherein the surface coating film mainly contains a silicone resin or a fluorine-containing resin. 3. The antibacterial property according to claim 1, wherein the base film is a coating film mainly containing a silicone resin or a fluorine-containing resin, or a transparent inorganic oxide film formed by physical or chemical vapor deposition. Wood board.