JP2022159274A - Laminate of moisture-proof film and wooden base material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate of a moisture-proof film and a wooden base material, which is used for a decorative material for floor and has suppressed occurrence of warpage and pull-bent, even when a decorative sheet having low moisture permeability is laminated on a front surface of a wooden base material.

SOLUTION: Provided is a laminate A of a moisture-proof film and a wooden base material, which is used for a decorative material for floor having a laminate structure comprising a decorative sheet, a wooden base material and a moisture-proof film from a front surface to a rear face, wherein (1) the moisture-proof film is a laminate B that has moisture permeability of 1 g/m² 24 hr or less and has a primer layer composed of a two-pack curable urethane-based resin, an aluminum vapor-deposited layer and a surface coat layer containing a polyvinyl alcohol-based resin in this order on one surface of a thermoplastic resin film, and (2) the wooden base material has a dimensional change per 1% water content change of more than 0.02% and an average water content of 6-10 wt.%.

SELECTED DRAWING: None

COPYRIGHT: (C)2023,JPO&INPIT

Description

TECHNICAL FIELD The present invention relates to a decorative floor material in which warping and bending are suppressed.

Traditionally, wood-based decorative boards used as decorative flooring materials for houses have a natural wood design by applying an adhesive to the upper surface of a wood-based base material (for example, hardwood lauan plywood) obtained from high-quality raw wood. A sheet to which a decorative sheet is adhered is known.

Lauan, which is a broad-leaved tree, is widely used as a woody base material. This problem is particularly serious for broadleaf trees such as lauan. Therefore, the development of wood base materials that can be used in place of lauan plywood is underway. Examples of lauan substitute materials include, for example, softwood plywood, wood boards formed by molding and solidifying wood fibers or wood pieces separated from wood waste wood with an adhesive (e.g., medium density wood fiber boards: MDF, high density wood fiber boards). : HDF, particle board: PB), and fast-growing plywood made from fast-growing trees.

However, these lauan substitute materials have a problem that the dimensional change amount per 1% moisture content change is larger than that of lauan plywood, and the dimensional change is likely to occur in response to changes in the surrounding environment. Specifically, the amount of dimensional change per 1% moisture content of lauan plywood is 0.015 to 0.02%, but about 0.045% for MDF and PB, and 0 for softwood plywood (for example, radiata pine). .025%. For this reason, lauan substitute materials tend to warp or bend (the right angle of the floor surface deviates) due to changes in humidity.

In order to solve the above problems, it has been proposed to laminate a moisture-proof sheet on the back surface of the lauan substitute material (for example, Patent Documents 1 to 3). However, the moisture-proof sheets described in Patent Documents 1 to 3 have a moisture permeability of at most about 20 g/m ² ·24 hours, and the performance is insufficient to prevent the lauan substitute material from warping or bending. Especially in recent years, decorative sheets with low moisture permeability (2 g/m ² for 24 hours or less) are often laminated on the front surface of lauan substitute materials, so the moisture permeability of the back surface is equal to or higher than that of the front surface. It is required to lower the moisture permeability.

From the above, even when a lauan substitute material with a dimensional change of more than 0.02% per 1% moisture content change is used as a wood base material, and a decorative sheet with low moisture permeability is laminated on the front surface, There is a demand for the development of a decorative floor material that suppresses the occurrence of warping and bending.

JP-A-2001-193267 Japanese Patent Application Laid-Open No. 2001-260109 JP 2006-097321 A

The present invention uses a lauan substitute material with a dimensional change of more than 0.02% per 1% moisture content change as a wood base material, and even when a decorative sheet with low moisture permeability is laminated on the front surface. An object of the present invention is to provide a decorative floor material that suppresses the occurrence of warping and bending.

As a result of extensive studies, the inventors have found that the above objects can be achieved by using a specific moisture-proof film, and have completed the present invention.

That is, the present invention relates to the following laminate of a moisture-proof film and a wooden substrate.
1. A laminate A of the moisture-proof film and the wooden base used for a decorative floor material having a laminated structure comprising a decorative sheet, a wooden base, and a moisture-proof film from the front surface to the back,
(1) The moisture-proof film is
Moisture permeability is 1 g / m ² · 24 hours or less,
A laminate B comprising a primer layer made of a two-component curable urethane resin on one side of a thermoplastic resin film, an aluminum deposition layer, and a surface coat layer containing a polyvinyl alcohol resin in that order,
(2) The wooden base material has a dimensional change of more than 0.02% per 1% moisture content change, and an average moisture content of 6 to 10% by weight.
A laminate A of a moisture-proof film and a wooden substrate characterized by:
2. 3. The moisture-proof film according to Item 1, wherein the laminate B further comprises, on one or both sides thereof, an adhesive primer layer made of a two-component curing resin containing a main agent containing a urethane resin and a curing agent containing an isocyanate. and a wood base material.
3. 3. A laminate A of a moisture-proof film and a wooden substrate according to Item 2, wherein the base material is a mixture of the urethane resin and the nitrocellulose resin.

The floor decorative material of the present invention will be described in detail below.

The decorative floor material of the present invention is a decorative floor material in which a decorative sheet is laminated on the front surface of a wooden base material, and a moisture-proof film is laminated on the back surface of the wooden base material,
(1) The wooden substrate has a dimensional change of more than 0.02% per 1% change in moisture content, and (2) The moisture-proof film has a moisture permeability of 7 g/m ² 24 hours or less. characterized by The moisture permeability is a value measured under an environment of temperature 40° C. and humidity 90% RH according to JIS Z0208 (moisture permeability test method (cup method)). Hereinafter, the moisture permeability in this specification indicates the measured value under the conditions.

The decorative floor material of the present invention having the above characteristics has a moisture-proof film having a moisture permeability of 7 g/m ² ·24 hours or less, so that the moisture permeability of the back surface of the wooden substrate is kept low. Therefore, even when a lauan substitute material having a dimensional change of more than 0.02% per 1% moisture content change is used as the wood base material and a decorative sheet with low moisture permeability is laminated on the front surface, the wood base material Since the moisture permeability of the front surface and the back surface of the material can be set to the same level, the occurrence of warping and bending of the decorative floor material is sufficiently suppressed. Such a decorative floor material of the present invention is suitable as a decorative floor material applied to floor surfaces of various buildings and as a decorative floor material used for floor heating as a special application.

Each configuration of the decorative floor material of the present invention will be described below.
(wood base material)
A lauan substitute material is used as the wood substrate of the present invention. In other words, it is a material that can replace conventional lauan plywood or the like, and for example, at least one of medium-density wood fiberboard (MDF), high-density wood fiberboard (HDF), particle board (PB), softwood plywood, precocious plywood, etc. Use seeds. Precocious trees include poplar, falcata, acacia, chamelele, eucalyptus, terminalaria, and the like. These lauan substitute materials exhibit greater than 0.02% dimensional change per 1% moisture content change.

The term "dimensional change amount per 1% moisture content" used herein is the dimensional change amount measured by the following procedure.
(1) Prepare a test piece of a wooden substrate cut to 300 mm×303 mm.
(2) Under normal temperature (25° C.) environment, measure the current dimensions (length of four sides) of the test piece with a vernier caliper. (3) Leave the test piece in a 40° C. oven (humidity free, dry atmosphere≈0%) for one week.
(4) After one week, measure the weight and dimensions (length of four sides) of the test piece.
(5) Measure the dimensional change per 1% moisture content change from the measurement data under both conditions.

Although the thickness of the wooden base material is not particularly limited, it is preferably about 2 to 15 mm, more preferably about 2 to 12 mm.

In the present invention, in preparation for the case where the decorative floor material is cut according to the construction site and used, the wooden base material has an average moisture content of 6 to 10% by weight, and the moisture content of the central portion is lower than that of the peripheral portion. It is preferred to use wood substrates with a moisture content in the range of -1% to +2%. If the size of the wooden substrate is, for example, about 150 mm long x 1840 mm wide (especially the length of the short side is 200 mm or less), warping or bending may occur due to uneven moisture content between the central and peripheral portions of the wooden substrate. becomes more likely to occur. Therefore, by setting the moisture content characteristics of the wooden base material to the above conditions, it is possible to suppress the occurrence of warpage and bending even when the decorative floor material is cut and used. As for the case where the floor covering material is cut and used, specifically, it is assumed that the floor covering material is applied to the corner portion (by the wall or around the pillar) of the room where the floor covering material is to be applied.

The average moisture content of the wooden substrate is preferably 6 to 10% by weight, more preferably 6.5 to 8% by weight. If the average moisture content is within the above range, it is easy to suppress the occurrence of bending and warping after cutting. Among them, when the floor decorative material is used for floor heating, it is preferable to set the average moisture content to 6 to 9% by weight.

Regarding the water content of the wood base material, the water content in the central part is preferably in the range of -1% to +2%, and in the range of -0.5% to +1% compared to the water content in the peripheral part. is more preferred. The peripheral portion of the wooden base means a 5 cm area around the wooden base, and the central portion of the wooden base means the inside of the wooden base excluding the peripheral portion.

In the present specification, the average moisture content and the moisture content difference of the wood substrate (hereinafter, "moisture content difference" indicates the moisture content difference between the peripheral portion and the central portion of the wooden substrate) are measured by the following procedure. is the value to be
(A) As shown in FIG. 3, prepare a wooden base material with a length of 303 mm and a width of 1818 mm.
(B) A 5 cm range from the periphery of the wooden base material is defined as the peripheral part, and the inner part thereof is defined as the central part. Thirty-five 5 cm x 5 cm samples are taken evenly as indicated by 1 to 35 in Fig. 3, and the moisture content is measured by the completely dry method. The completely dry method is a method in which each sample is left in an oven at 105° C. for 3 days, and then the moisture content of each sample is measured using the following formula. Before standing is called pre-treatment, and after standing is called post-treatment.

Moisture content (%) = {(weight before treatment - weight after treatment) / weight after treatment} x 100
(C) Let the average value of 35 samples be "average moisture content."
(D) The value obtained by subtracting the average value of the peripheral samples (20) from the average value of the central samples (15) is defined as the "moisture content difference".
(decorative sheet)
A decorative sheet is laminated on the front surface of the wooden base material. The decorative sheet preferably has a moisture permeability of 7 g/m ² ·24 hours or less at a temperature of 40°C and a humidity of 90%, more preferably 5 g/m ² ·24 hours or less. Although the structure of the decorative sheet is not limited, for example, it is preferable to have a pattern layer (solid ink layer/patterned ink layer), a transparent resin layer and a surface protection layer in this order on a base sheet. The decorative sheet will be exemplified below.

As the base sheet, 1) paper such as thin paper, fine paper, kraft paper, Japanese paper, titanium paper, resin-impregnated paper, paper reinforced paper, etc. 2) wood fiber, glass fiber, asbestos, polyester fiber, vinylon fiber, rayon Laminates of one or more of woven fabrics or non-woven fabrics made of fibers or the like, and 3) synthetic resin sheets such as polyolefin, polyester, polyacryl, polyamide, polyurethane, and polystyrene.

The thickness of the base sheet is preferably about 20-300 μm. The base sheet may be colored if necessary. Further, the surface may be subjected to surface treatment such as corona discharge treatment, plasma treatment, ozone treatment, or the like.

The pattern layer is composed of a pattern ink layer and/or a solid ink layer. The pattern layer can be formed by a printing method such as gravure printing, offset printing, or silk screen printing. The pattern of the pattern ink layer includes, for example, a wood grain pattern, a stone grain pattern, a texture pattern, a leather pattern, a geometric pattern, characters, symbols, line drawings, various abstract patterns, and the like. The solid ink layer is obtained by solid printing with colored ink. The pattern layer is composed of one or both of a pattern ink layer and a solid ink layer.

The ink used for the pattern layer includes, as a vehicle, chlorinated polyolefin such as chlorinated polyethylene and chlorinated polypropylene, polyester, polyurethane composed of isocyanate and polyol, polyacryl, polyvinyl acetate, polyvinyl chloride, vinyl chloride-vinyl acetate One or a mixture of two or more of polymers, cellulose resins, polyamide resins, etc. may be used, and pigments, solvents, various auxiliary agents, etc. may be added thereto to form inks. Among these, one or a mixture of two or more of polyesters, polyurethanes composed of isocyanates and polyols, polyacrylics, polyamide resins, and the like is preferable from the viewpoints of environmental concerns, adhesion to the surface to be printed, and the like.

The transparent resin layer is not particularly limited as long as it is a transparent resin layer. For example, it can be suitably formed from a transparent thermoplastic resin.

Specifically, soft, semi-rigid or rigid polyvinyl chloride, polyethylene terephthalate, polybutylene terephthalate, polyamide, polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic ester copolymer Polymers, ionomers, acrylic acid esters, methacrylic acid esters and the like can be mentioned. Among the above, polyolefin resins such as polypropylene are preferred.

The transparent resin layer may be colored. In this case, a colorant may be added to the thermoplastic resin. Pigments or dyes used in the pattern layer can be used as the colorant.

Fillers, matting agents, foaming agents, flame retardants, lubricants, antistatic agents, antioxidants, UV absorbers, light stabilizers, radical scavengers, soft components (e.g. rubber) are contained in the transparent resin layer. Various additives such as may be included.

The surface protective layer (transparent surface protective layer) is provided to impart surface physical properties such as scratch resistance, abrasion resistance, water resistance and stain resistance required for the decorative sheet. As the resin for forming this surface protective layer, a curable resin such as a thermosetting resin or an ionizing radiation curable resin is preferable. In particular, ionizing radiation-curable resins are preferable from the viewpoint of high surface hardness, productivity, and the like.

Thermosetting resins include, for example, unsaturated polyester resins, polyurethane resins (including two-component curing polyurethanes), epoxy resins, aminoalkyd resins, phenolic resins, urea resins, diallyl phthalate resins, melamine resins, guanamine resins, and melamine. - urea co-condensation resin, silicone resin, polysiloxane resin and the like.

A crosslinking agent, a curing agent such as a polymerization initiator, and a polymerization accelerator can be added to the above resin. For example, as curing agents, isocyanates, organic sulfonates and the like can be added to unsaturated polyester resins and polyurethane resins, organic amines and the like can be added to epoxy resins, peroxides such as methyl ethyl ketone peroxide, and azoisobutylnitrile can be added. A radical initiator can be added to the unsaturated polyester resin.

Examples of the method of forming the surface protective layer with a thermosetting resin include a method of applying a thermosetting resin solution by a coating method such as a roll coating method or a gravure coating method, followed by drying and curing. The coating amount of the solution is about 5 to 30 μm, preferably about 5 to 20 μm in terms of solid content.

The ionizing radiation-curable resin is not limited as long as it is a resin that undergoes a cross-linking polymerization reaction when irradiated with ionizing radiation and changes into a three-dimensional polymer structure. For example, one or more of prepolymers, oligomers and monomers having polymerizable unsaturated bonds or epoxy groups in the molecule that can be crosslinked by irradiation with ionizing radiation can be used. Examples thereof include acrylate resins such as urethane acrylate, polyester acrylate and epoxy acrylate; silicone resins such as siloxane; polyester resins; and epoxy resins.

Ionizing radiation includes visible light, ultraviolet rays (near ultraviolet rays, vacuum ultraviolet rays, etc.), X-rays, electron beams, ion beams, etc. Among these, ultraviolet rays and electron beams are preferable.

Ultra-high pressure mercury lamps, high pressure mercury lamps, low pressure mercury lamps, carbon arc lamps, black light fluorescent lamps, and metal halide lamps can be used as ultraviolet light sources. The wavelength of ultraviolet rays is about 190 to 380 nm.

As the electron beam source, for example, various electron beam accelerators such as Cockcroftwald type, Vandegraft type, resonance transformer type, insulating core transformer type, linear type, dynamitron type, and high frequency type can be used. The electron beam energy is preferably about 100 to 1000 keV, more preferably about 100 to 300 keV. The electron beam irradiation dose is preferably about 2 to 15 Mrad.

Ionizing radiation-curable resins are sufficiently cured by irradiation with electron beams, but when curing by irradiation with ultraviolet rays, it is preferable to add a photopolymerization initiator (sensitizer).

Photoinitiators for resin systems having radically polymerizable unsaturated groups include, for example, acetophenones, benzophenones, thioxanthones, benzoin, benzoin methyl ether, Michler benzoyl benzoate, Michler ketone, diphenyl sulfide, dibenzyl disulfide. , diethyl oxide, triphenylbiimidazole, isopropyl-N,N-dimethylaminobenzoate and the like can be used. In the case of a resin system having a cationic polymerizable functional group, for example, at least one of aromatic diazonium salts, aromatic sulfonium salts, metallocene compounds, benzoinsulfonic acid esters, freeloxysulfoxonium diallyiodosyl salts, and the like. can be used.

The amount of the photopolymerization initiator to be added is not particularly limited, but is generally about 0.1 to 10 parts by weight with respect to 100 parts by weight of the ionizing radiation-curable resin.

As a method for forming a protective layer with an ionizing radiation-curable resin, for example, a solution of an ionizing radiation-curable resin may be applied by a coating method such as gravure coating or roll coating. The coating amount of the solution is about 5 to 30 μm, preferably about 5 to 20 μm in terms of solid content.

In order to further impart scratch resistance and wear resistance to the surface protective layer formed from the ionizing radiation curable resin, an inorganic filler may be blended. Examples of inorganic fillers include powdery aluminum oxide, silicon carbide, silicon dioxide, calcium titanate, barium titanate, magnesium pyroborate, zinc oxide, silicon nitride, zirconium oxide, chromium oxide, iron oxide, boron nitride, Examples include diamond, emerald sand, and glass fiber.

The amount of the inorganic filler to be added is about 1 to 80 parts by weight with respect to 100 parts by weight of the ionizing radiation curable resin.

Lamination of each layer is performed by, for example, forming a pattern layer (solid ink layer, pattern ink layer) on one surface of the base sheet by printing in order, and then applying a known dry lamination adhesive such as a two-liquid curing urethane resin on the pattern layer. It can be carried out by laminating a transparent resin layer with an agent interposed therebetween by a dry lamination method, a T-die extrusion method, or the like, and further forming a surface protective layer.

An uneven pattern may be formed by embossing from the surface protective layer side. The uneven pattern can be formed by hot pressing, hairline processing, or the like. Concavo-convex patterns include conduit grooves, slate surface irregularities, cloth surface textures, satin finish, grain, hairline, parallel grooves, and the like.

The decorative sheet may have a synthetic resin layer (so-called backer layer) having a thickness of 100 μm or more as the lowermost layer (layer adhered to the wooden substrate). In addition, the backer layer means a buffer layer for the purpose of impact absorption and the like in the decorative floor material. Materials constituting the backer layer include, for example, polypropylene, ethylene-vinyl alcohol copolymer, polymethylene, polymethylpentene, polyethylene terephthalate, polyalkylene terephthalate with high heat resistance [for example, ethylene glycol is partially replaced with 1,4- Polyethylene terephthalate substituted with cyclohexanedimethanol, diethylene glycol, etc., so-called trade name PET-G (manufactured by Eastman Chemical Company)], polybutylene terephthalate, polyethylene naphthalate, polyethylene naphthalate-isophthalate copolymer, polycarbonate, poly Arylate, polyimide, polystyrene, polyamide, ABS and the like. These resins can be used singly or in combination of two or more. Although the upper limit of the thickness of the backer layer is not limited, 600 μm is suitable.

A known adhesive can be used when laminating the decorative sheet on the wooden substrate. Examples of adhesives include polyvinyl acetate, polyvinyl chloride, vinyl chloride/vinyl acetate copolymer, ethylene/acrylic acid copolymer, ionomer, butadiene/acrylonitrile rubber, neoprene rubber, natural rubber, etc., as active ingredients. and adhesives. Although the thickness of the adhesive layer is not limited, it is preferably about 0.1 to 50 μm.
(moisture-proof film)
A moisture-proof film is provided on the back surface of the wooden substrate. In the present invention, the moisture-proof film used has a moisture permeability of 7 g/m ² ·24 hours or less at a temperature of 40° C. and a humidity of 90%. Among them, those having a moisture permeability of 5 g/m ² ·24 hours or less are preferable.

The moisture-proof film is not limited as long as it satisfies the above-mentioned moisture permeability. Available. Among these, those having at least a synthetic resin substrate layer and a deposition layer are particularly preferable. This aspect will be described below with an example.

The synthetic resin substrate layer includes olefinic thermoplastic resins such as polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl alcohol copolymer, and mixtures thereof; polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, Ester thermoplastic resins such as polyethylene naphthalate-isophthalate copolymer, polycarbonate, and polyarylate; Acrylic thermoplastic resins such as polymethyl methacrylate, polyethyl methacrylate, and polybutyl acrylate; polyimide, polyurethane, Examples include non-halogen thermoplastic resins such as polystyrene and acrylonitrile-butadiene-styrene resins.

The synthetic resin substrate layer may be a uniaxially or biaxially stretched sheet, or may be unstretched. It is preferable that the synthetic resin base material layer is further laminated with a vapor deposition layer. A sheet that has been stretched in The suitable thickness of the synthetic resin substrate layer is approximately 9 to 25 μm.

Examples of the vapor deposition layer include vapor deposition layers of inorganic substances composed of metal thin films typified by aluminum, and inorganic oxide vapor deposition layers composed of inorganic oxide thin films typified by silicon oxide, magnesium oxide and aluminum oxide. The vapor deposition layer is formed on the synthetic resin substrate layer by a well-known vapor deposition method such as a vacuum vapor deposition method or a plasma activated chemical reaction vapor deposition method. More preferably, the deposited layer is a transparent inorganic oxide deposited layer.

A surface coat layer may be provided on the vapor deposition layer for the purpose of further improving the gas barrier properties of the vapor deposition layer. A polyvinyl alcohol-based resin is used as the surface coat layer. Further, the general formula R ¹ _n M (OR ² ) _m (wherein R ¹ and R ² represent an organic group having 1 to 8 carbon atoms, M represents a metal atom, and n is an integer of 0 or more) where m represents an integer of 1 or more, and n+m represents the valence of M), and at least one or more alkoxides represented by: and also compositions prepared by polycondensation by the sol-gel process in the presence of a sol-gel process catalyst, acid, water and an organic solvent. Further, by combining polyvinyl alcohol and ethylene-vinyl alcohol copolymer, gas barrier properties, water resistance, weather resistance, etc. are remarkably improved. A silane coupling agent or the like may be added to the above composition. A surface coat layer can be obtained by applying these resins or compositions onto the deposited layer by a well-known coating method such as a roll coating method or a gravure coating method. The surface coat layer also functions as a protective layer for the vapor deposition layer, and its thickness is appropriately about 1 to 10 μm.

The synthetic resin substrate layer and/or the surface coat layer may be subjected to surface treatment such as corona treatment, if necessary. Such surface treatment can further increase the adhesive strength with the adjacent layer.

In the present invention, a primer layer may be further provided between the synthetic resin substrate layer and the deposited layer and on one or both sides of the moisture-proof film. Therefore, a preferred embodiment of the moisture-proof film is, for example, the embodiment of "synthetic resin base layer/primer layer/vapor-deposited layer/surface coating layer", and furthermore, a primer layer is provided on one or both sides of the moisture-proof film. Any form is fine.

These primer layers are provided to enhance the adhesion between the synthetic resin substrate layer and the deposition layer, and to enhance the adhesion when laminating the moisture-proof film to another layer.

Examples of resins used for such a primer layer include ester-based resins, urethane-based resins, acrylic-based resins, polycarbonate-based resins, vinyl chloride-vinyl acetate copolymers, polyvinyl butyral-based resins, nitrocellulose-based resins, and the like. and these resins can be used singly or in combination. Formation of the primer layer can be carried out using an appropriate coating means such as a roll coating method or a gravure printing method.

Among these, the primer layer is preferably formed from (i) a copolymer of acrylic resin and urethane resin and (ii) isocyanate. That is, the copolymer of acrylic resin and urethane resin (i) includes an acrylic polymer component (component A) having hydroxyl groups at the ends, a polyester polyol component (component B) having hydroxyl groups at both ends, and a diisocyanate component (component C) is blended and reacted to form a prepolymer, and a chain extender (component D) such as diamine is added to the prepolymer to extend the chain. This reaction forms a polyester urethane and introduces an acrylic polymer component into the molecule to form an acrylic-polyester urethane copolymer having terminal hydroxyl groups. The terminal hydroxyl groups of this acrylic-polyester urethane copolymer are reacted with the isocyanate (ii) and cured.

As the component A, a linear acrylate polymer having terminal hydroxyl groups is used. Specifically, linear polymethyl methacrylate (PMMA) having a terminal hydroxyl group is preferred because it has excellent weather resistance (especially properties against light deterioration) and is easy to copolymerize with urethane. Component A serves as an acrylic resin component in the copolymer, and those having a molecular weight of 5,000 to 7,000 (weight average molecular weight) are preferably used because of their particularly good weather resistance and adhesiveness. In addition, as the component A, only one having hydroxyl groups at both ends may be used. good too.

Component B reacts with diisocyanate to form polyester urethane, and constitutes the urethane resin component in the copolymer. As the component B, a polyester diol having hydroxyl groups at both ends is used. The polyester diol includes a diol compound having an aromatic or spiro ring skeleton and a lactone compound or a derivative thereof, an addition reaction product with an epoxy compound, a condensation product of a dibasic acid and a diol, and a cyclic ester compound. Induced polyester compounds and the like can be mentioned. Examples of the diol include short-chain diols such as ethylene glycol, propylene glycol, diethylene glycol, butanediol, hexanediol, and methylpentenediol; and alicyclic short-chain diols such as 1,4-cyclohexanedimethanol. can. Dibasic acids include adipic acid, phthalic acid, isophthalic acid and terephthalic acid. Preferred as the polyester polyol is adipic acid or a mixture of adipic acid and terephthalic acid, particularly adipic acid, as the acid component, and an adipate system using 3-methylpentenediol and 1,4-cyclohexanedimethanol as the diol component. Polyester.

In the primer layer, the urethane resin component formed by the reaction between the component B and the component C imparts flexibility to the primer layer and contributes to improvement in adhesiveness. In addition, the acrylic resin component composed of an acrylic polymer contributes to the weather resistance and blocking resistance of the primer layer. In the urethane resin, the molecular weight of the component B may be within a range where a urethane resin capable of sufficiently exhibiting flexibility in the primer layer can be obtained. and 1,4-cyclohexanedimethanol, preferably 500 to 5000 (weight average molecular weight).

Component C is an aliphatic or alicyclic diisocyanate compound having two isocyanate groups in one molecule. Examples of the diisocyanate include tetramethylene diisocyanate, 2,2,4(2,4,4)-1,6-hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 1,4'-cyclohexyl Diisocyanate and the like can be mentioned. As the diisocyanate component, isophorone diisocyanate is preferable in terms of physical properties and cost. When the above components A to C are reacted, the equivalent ratio of the total hydroxyl group (sometimes amino group) of the acrylic polymer, polyester polyol and chain extender described later and the isocyanate group is such that the isocyanate group is excessive. to

When the above three components A, B, and C are reacted at 60 to 120° C. for about 2 to 10 hours, the isocyanate group of the diisocyanate reacts with the hydroxyl group at the end of the polyester polyol to form a polyester urethane resin component and an acrylic polymer. A compound in which a diisocyanate is added to a terminal hydroxyl group is also mixed, forming a prepolymer in which excessive isocyanate groups and hydroxyl groups remain. A diamine such as isophoronediamine or hexamethylenediamine is added as a chain extender to this prepolymer, and the isocyanate group is reacted with the chain extender to chain extend the acrylic polymer component into the molecule of the polyester urethane. It is possible to obtain an acrylic-polyester urethane copolymer (i) having a terminal hydroxyl group.

The isocyanate (ii) is added to the acrylic-polyester urethane copolymer (i), and the coating solution is adjusted to the necessary viscosity in consideration of the coating method and the coating amount after drying. The primer layer may be formed by coating using a known coating method such as a coating method. As the isocyanate (ii), any one can be used as long as it can react with the hydroxyl groups of the acrylic-polyester urethane copolymer (i) to be crosslinked and cured. Aliphatic isocyanates can be used, and aliphatic isocyanates are particularly desirable from the viewpoint of heat discoloration prevention and weather resistance. Specifically, tolylene diisocyanate, xylylene diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, lysine diisocyanate monomers, dimers, trimers and other multimers thereof, or these polyisocyanate such as a derivative (adduct) obtained by adding the isocyanate of (1) to a polyol.

The coating amount of the primer layer after drying is 1 to 20 g/m ² , preferably 1 to 5 g/m ² . In addition, the primer layer may be a layer to which fillers such as silica powder, additives such as light stabilizers and coloring agents are added, if necessary.

A known adhesive can be used when laminating the moisture-proof sheet on the wooden substrate. Examples of adhesives include polyvinyl acetate, polyvinyl chloride, vinyl chloride/vinyl acetate copolymer, ethylene/acrylic acid copolymer, ionomer, butadiene/acrylonitrile rubber, neoprene rubber, natural rubber, etc., as active ingredients. and adhesives. Although the thickness of the adhesive layer is not limited, it is preferably about 0.1 to 50 μm.

Since the decorative floor material of the present invention has a moisture-proof film having a moisture permeability of 7 g/m ² ·24 hours or less, the moisture permeability of the back surface of the wooden substrate is kept low. Therefore, even when a lauan substitute material having a dimensional change of more than 0.02% per 1% moisture content change is used as the wood base material and a decorative sheet with low moisture permeability is laminated on the front surface, the wood base material Since the moisture permeability of the front surface and the back surface of the material can be set to the same level, the occurrence of warping and bending of the decorative floor material is sufficiently suppressed. Such a decorative floor material of the present invention is suitable as a decorative floor material applied to floor surfaces of various buildings and as a decorative floor material used for floor heating as a special application.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram (one example) of a decorative floor material of the present invention; FIG. 4 is a schematic diagram showing warpage and bending of the decorative floor material. FIG. 2 is a diagram showing samples used for measuring the average moisture content and moisture content difference of a wood substrate; 1 is a schematic diagram of Floor Heating System Test Standard II. FIG.

1. Cosmetic sheet2. Adhesive layer3. Wood base material (lauan substitute material)
4. Adhesive layer 5 . moisture proof film

EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples. However, the present invention is not limited to the examples.

Example 1
(1) A decorative sheet (0.4 mm) containing a synthetic resin layer is attached to a 5.5 mm thick MDF (wood base material) using an adhesive (BA-10L/BA-11B, 9 g/shakuaku) manufactured by Chuo Rika Kogyo Co., Ltd. was attached to the front surface of the The dimensional change rate per 1% moisture content change of the MDF was 0.05%. The shakukaku means the area of a plane represented by 303 mm in length and 303 mm in width (the same shall apply hereinafter).
(2) A moisture-proof film was attached to the back surface of the MDF using an adhesive (BA-10L/BA-11B, 9 g/shaku) manufactured by Chuo Rika Kogyo Co., Ltd. A laminate in this state is called a decorative board.
(3) The veneer was cut to a size of 313 mm long x 1840 mm wide with a gang saw.
(4) In addition, tongue processing, edge chamfering, and V-groove processing (V-groove processing width: 1.5 mm) were performed using a tenoner processing machine.
(5) Further, in a coating line, paint was applied (paint: paint containing a two-liquid curing type urethane resin) to the tongue processed portion, the end chamfered portion, and the V-groove processed portion.

A decorative floor material was produced through the above steps.

The moisture-proof film was produced as follows. That is, a biaxially oriented polyethylene terephthalate film having a thickness of 12 μm was prepared, and a primer layer made of a two-liquid curing type urethane resin was provided on one side of the film. Furthermore, an aluminum deposition layer was provided on the primer layer. The film thus obtained is called a "vapor-deposited PET film".

A PVA/silicate-based surface coating layer of 0.2 g/m ² (dry state) was formed on the vapor-deposited PET film, and a laminate (synthetic resin substrate layer (PET)/vapor-deposited layer/surface coating layer) was formed. was made. After both surfaces of the laminate were subjected to corona discharge treatment, a two-component curing type resin obtained by adding a curing agent (isocyanate) to the main component (a mixture of a urethane resin and a nitrocellulose resin) was applied by gravure printing to a solid content of 5 g each. /m ² to form adhesion primer layers on both sides. As a result, a moisture-proof film (water vapor permeability of 1 g/m ² for 24 hours) was obtained.

Example 2
A decorative floor material was produced in the same manner as in Example 1, except that a 9 mm thick particle board (0.049% dimensional change per 1% change in water content) was used as the wooden substrate.

Example 3
A decorative floor material was produced in the same manner as in Example 1, except that a 12 mm thick softwood plywood (radiata pine, 0.026% dimensional change per 1% change in water content) was used as the wooden substrate.

Example 4
A decorative floor material was produced in the same manner as in Example 1, except that PE (polyethylene sheet, moisture permeability 7 g/m ² ·24 hours) was used as the moisture-proof film.

Comparative example 1
A decorative floor material was produced in the same manner as in Example 1, except that the moisture-proof film was not used.

Comparative example 2
A decorative floor material was produced in the same manner as in Example 2, except that the moisture-proof film was not used.

Comparative example 3
A decorative floor material was produced in the same manner as in Example 3, except that the moisture-proof film was not used.

Comparative example 4
A decorative floor material was produced in the same manner as in Example 1, except that moisture-proof paper (polyethylene core layer laminated on both sides with paper, moisture permeability 10 g/m ² for 24 hours) was used as the moisture-proof film. .

Conventional example 1
A decorative floor material was produced in the same manner as in Example 1, except that a lauan plywood with a thickness of 12 mm (the dimensional change rate per 1% change in water content was 0.016%) was used as the wooden base material, and the moisture-proof film was not used. did.

Test Example 1 (warp and bending at 40°C atmosphere)
The decorative floor materials prepared in Examples 1 to 4, Comparative Examples 1 to 4, and Conventional Example 1 were left in an atmosphere (dry atmosphere) at 40°C (for 7 days), and the amounts of warpage and bending of the decorative floor materials were measured. was measured.

FIG. 2 shows a schematic diagram of the amount of warpage and the amount of bending. The amount of warpage and the amount of bending was measured with a feeler gauge. If the amount of warp is 20 mm/1840 mm (the amount of warp relative to the horizontal length) or less, it is acceptable (suitable for practical use). Also, a bending amount of 0.3 mm/1840 mm (amount of bending with respect to the horizontal length) or less is acceptable (suitable for practical use). Table 1 shows the results.

Test Example 2 (warpage and bending at 40°C and 90% RH atmosphere)
The decorative floor materials prepared in Examples and Comparative Examples were left in an atmosphere of 40° C. and 90% RH (for 7 days), and the amounts of warpage and bending of the decorative floor materials were measured in the same manner as in Test Example 1. . Table 1 shows the results.

As is clear from the results in Table 1 above, the floor decorative material of the present invention provided with a moisture-proof film having a moisture permeability of 7 g/m ² ·24 hours or less has a moisture-proof film. Change is effectively suppressed. As a result, the decorative floor material is prevented from warping and bending, and the results are closer to those of the conventional example 1 (using lauan plywood).

Example 5
(1) Floor decorative sheet (0.16 mm thickness, moisture permeability: 3 g/m ² 24 hours), 12 mm thickness using Chuo Rika Kogyo adhesive (BA-10L/BA-11B, 9 g/shaku) was attached to the front surface of the particle board (PB) (woody base material). The dimensional change rate per 1% moisture content change of the PB was 0.045%, and the average moisture content was 6.5% by weight.
(2) On the back of the PB, an adhesive (BA-10L/BA-11B, 9g/shaku) made by Chuo Rika Kogyo was applied to a moisture-proof film (PET film + vapor deposition layer, moisture permeability: 3g/m ² 24 hours ) were pasted together. A laminate in this state is called a decorative board.
(3) The veneer was cut to a size of 313 mm long x 1840 mm wide with a gang saw.
(4) In addition, tongue processing, edge chamfering, and V-groove processing (V-groove processing width: 1.5 mm) were performed using a tenoner processing machine.
(5) Further, in a coating line, paint was applied (paint: paint containing a two-liquid curing type urethane resin) to the tongue processed portion, the end chamfered portion, and the V-groove processed portion.

A decorative floor material was produced through the above steps. Between each step, the decorative plate was covered with a PP film (thickness: 30 μm, moisture permeability: 15 g) to prevent moisture.

Example 6
A decorative floor material was produced in the same manner as in Example 5, except that moisture-proof treatment using a PP film was not performed between each step. As a result, the moisture content of the peripheral portion of the wooden substrate was made higher than that of the central portion.

Example 7
A decorative floor material was produced in the same manner as in Example 5, except that a PB base material having a moisture content in the central part of the wooden base material that was 2% higher than that in the peripheral part was used.

Example 8
A decorative floor material was produced in the same manner as in Example 5, except that softwood plywood was used in which the moisture content in the central portion of the wooden substrate was 1.7% higher than that in the peripheral portion.

Comparative example 5
A decorative floor material was produced in the same manner as in Example 6, except that PB having an average moisture content of 5.5% was used as the wooden base material.

Comparative example 6
A decorative floor material was produced in the same manner as in Example 6, except that after tenona processing, the material was allowed to stand for one week without being subjected to moisture-proof treatment.

Comparative example 7
A decorative floor material was produced in the same manner as in Example 5, except that a PB base material was used in which the water content in the woody central portion was 2.5% higher than that in the peripheral portion.

Comparative example 8
A decorative floor material was produced in the same manner as in Example 5, except that the average moisture content was adjusted to 10.5%, and a PB base material was used in which the moisture content in the woody central portion was 1.3% lower than that in the peripheral portion.

Test Example 3 (Evaluation of bending and construction suitability after cutting the decorative floor material)
<Evaluation of bending amount after cutting>
The decorative floor materials (313 mm long×1840 mm wide) produced in Examples 5 to 8 and Comparative Examples 5 to 8 were cut in half (150 mm long×1840 mm wide) at the center.

The lateral bending amount of the cut floor material was measured using a straight ruler and a clearance gauge. Measurements were taken within 30 minutes after cutting. As for the amount of bending, the state in which each tongue side (male tongue and female tongue) is convex is indicated by +.

In addition, the amount of bending after cutting is allowed if it is within the range of "-1.0 mm / 1840 mm in width to +0.7 mm / 1840 mm in width".
<Construction suitability evaluation>
The decorative floor materials (313 mm long×1840 mm wide) prepared in Examples 5 to 8 and Comparative Examples 5 to 8 were first constructed in the same size. After that, the decorative floor material was cut into about half (150 mm long x 1840 mm wide) at the center and applied within 30 minutes after the cut to evaluate the workability after the cut. The evaluation criteria were as follows.

◯: Like before cutting, construction can be performed without problems, and no gaps are observed in the seams.

Δ: Construction can be done with time and effort, and no gaps are observed in the seams.

x: Construction is difficult, and a gap exceeding 0.3 mm is observed at the seam.

Test Example 4 (floor heating system test)
The decorative floor materials (313 mm long×1840 mm wide) produced in Examples 5 to 8 and Comparative Examples 5 to 8 were subjected to a floor heating system test. Floor heating systems are generally not installed in the corners of a room (by walls or around pillars), but in the center of the room except for the corners. Therefore, in Test Example 4, a floor heating system test was performed on a decorative floor material (length 313 mm x width 1840 mm).

Specifically, a test piece was prepared by constructing a tongue-and-groove decorative floor material, and the floor heating system test shown in FIG. Time continuous hot water supply, gas company unified standard method).

For the specimen after the test,
(1) Passed if the amount of gap displacement in the tongue-and-groove part (fitting part) was 0.5 mm or less (2) Passed if the step-difference amount of the tongue-and-groove part (fitting part) was 0.5 mm or less (3) Horizontal If the amount of warp in the direction (1840 mm) (=width warp) was less than 1 mm, it was evaluated according to the acceptance criteria. A case where all of them passed was indicated by ◯, and a case where even one of the requirements was not satisfied was indicated by x.

Each evaluation/test result is shown in Table 2 below.

As is clear from the results in Table 2 above, the average water content is particularly 6 to 10% by weight, and the water content in the central portion is in the range of -1% to +2% compared to the water content in the peripheral portion. By using a wooden base material, bending after cutting can be effectively suppressed. Further, the decorative floor material of the present invention can be practically used as a floor heating floor material because the moisture permeability of the moisture-proof film is 7 g/m ² ·24 hours or less.

Claims (3)

A laminate A of the moisture-proof film and the wooden base used for a decorative floor material having a laminated structure comprising a decorative sheet, a wooden base, and a moisture-proof film from the front surface to the back,
(1) The moisture-proof film is
Moisture permeability is 1 g / m ² · 24 hours or less,
A laminate B comprising a primer layer made of a two-component curable urethane resin on one side of a thermoplastic resin film, an aluminum deposition layer, and a surface coat layer containing a polyvinyl alcohol resin in that order,
(2) The wooden base material has a dimensional change of more than 0.02% per 1% moisture content change, and an average moisture content of 6 to 10% by weight.
A laminate A of a moisture-proof film and a wooden substrate characterized by: The moisture-proof film according to claim 1, wherein the laminate B further comprises, on one or both sides thereof, an adhesion primer layer made of a two-component curing resin containing a main agent containing a urethane resin and a curing agent containing an isocyanate. and a wood base material. 3. The laminate A of a moisture-proof film and a wooden substrate according to claim 2, wherein the base material is a mixture of the urethane resin and the nitrocellulose resin.

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