JP5082540B2 - Decorative sheet - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a decorative sheet used as a building material such as an interior / exterior member for construction, a fitting, a frame material, a flooring material, or a surface material for home appliances, and mainly wood boards, inorganic boards, metals. The present invention relates to a decorative sheet used when a decorative sheet is produced by bonding to a plate or the like.

  Conventionally, as a decorative sheet used as a construction material such as an interior / exterior member for construction, joinery, frame material, flooring, or a surface material for home appliances, a sheet mainly composed of vinyl chloride resin is widely used. ing. However, vinyl chloride resin is said to generate chlorine gas during incineration, which is said to cause acid rain and dioxins. Furthermore, a sheet made of vinyl chloride resin has a plasticizer added to it. There is also a problem of bleeding out, and from the viewpoint of environmental problems, development of a decorative sheet that does not use a vinyl chloride resin has been strongly demanded.

  For the above reasons, in recent years, many decorative sheets using materials (non-vinyl chloride materials) that do not use vinyl chloride resins such as olefin resins have been proposed as alternatives to decorative sheets using vinyl chloride resins (for example, (See Patent Documents 1 to 4.)

  However, a non-vinyl chloride decorative sheet using a general polyolefin sheet or a flexible polyolefin sheet is significantly inferior in surface scratch resistance and weather resistance as compared with a conventional decorative sheet using a vinyl chloride resin. In order to improve surface scratch resistance, it may be possible to use a material with high crystallization and high isotacticity, but it tends to deteriorate the weather resistance.

  Therefore, there is an attempt to improve surface gloss adjustment and resistance to surface scratches by providing a resin layer made of another resin as a protective layer on the surface of the polyolefin sheet. In addition, since weather resistance is also required, there has been proposed that a weathering agent such as a UV absorber is added to the olefin resin sheet and a weathering agent is also added to the protective layer.

  However, depending on the type of weathering agent, there are many cases where even if added to the polyolefin sheet, the original function as a weathering agent cannot be sufficiently performed, and other adverse effects due to bleed-out are caused.

  On the other hand, various proposals to solve the problem of bleedout of weathering agents by providing a surface layer made of polyolefin containing no ultraviolet absorber or limiting the molecular weight of the ultraviolet absorber used are various. (For example, see Patent Documents 5 to 7.)

  For example, in Patent Document 5, a transparent containing only a hindered amine radical scavenger on a transparent olefin resin layer (intermediate layer) containing both a hindered amine radical scavenger as a light stabilizer and an ultraviolet absorber. Proposals have been made to suppress bleeding out of the ultraviolet absorbent added to the intermediate layer to the decorative sheet surface by providing the olefin-based resin layer (surface layer).

  Certainly this method can suppress the bleed-out of the UV absorber in the intermediate layer, but in general, a hindered amine light stabilizer and an UV absorber have a synergistic effect on the function. When a decorative sheet is used as a building material for exterior use, if there is a surface layer to which no UV absorber is added on the surface, the weather resistance of the surface layer is lower than that of the intermediate layer. Deterioration of physical properties, gloss change, cracking, choking, etc. in the surface layer accompanying the embrittlement of the sheet occur and the appearance is impaired.

  In order to prevent such a phenomenon, it is necessary to add a UV absorber having a high UV absorbing ability without causing bleed-out at a particularly high concentration. Patent Document 6 proposes a decorative sheet in which a protective layer made of a thermoplastic resin obtained by reactively bonding an ultraviolet absorbent having an ultraviolet absorbing ability to a side chain is disposed on a surface portion.

  Certainly, these UV absorbers rarely bleed out. However, although the initial ultraviolet absorbing ability is high, there is a problem that when exposed to light or rain wind outdoors, the ultraviolet absorbing ability is deactivated relatively quickly and the function as a weathering agent cannot be performed sufficiently.

  In addition, Patent Document 7 uses a triazine-based ultraviolet absorber having a low ultraviolet-absorbing ability and good weather resistance although having poor compatibility with a resin, and adding a molecular weight limited to a specific value or more. Proposals made are also made.

  However, when the molecular weight is limited to a specific value or more in this way, the bleed-out over time is surely suppressed, but it cannot be maintained permanently and is required as a decorative sheet that can withstand exterior use. It was not a decorative sheet having both bleed-out resistance and weather resistance on the surface.

Also known is an agricultural film comprising a polyolefin resin, a resin composition comprising an inorganic ultraviolet absorber composed of a triazine ultraviolet absorber and a metal oxide, and a hindered amine light stabilizer ( (See Patent Document 8). However, this resin composition is intended to transmit ultraviolet rays and is not suitable for a decorative sheet that requires excellent weather resistance.
JP-A-2-128843 JP-A-6-1881 JP-A-6-198831 JP 9-328562 A JP-A-11-147292 JP-A-11-216812 JP 2001-40113 A JP 2003-325060 A

  The present invention has been made to solve the above-mentioned problems, and the problem is that a decorative sheet having excellent weather resistance, in particular, the weather resistance is required for a surface material of a building material for exterior use. Another object of the present invention is to provide a decorative sheet characterized in that it can sufficiently satisfy the weather resistance.

According to the first aspect of the present invention, at least a protective layer containing a crosslinked polyurethane-based resin having a transparent or translucent crosslinking density of 1.0 to 2.0 (mmol / CC) is laminated on a base sheet. The protective layer comprises at least one UV absorber selected from the group consisting of triazine UV absorbers, benzotriazole UV absorbers, and inorganic UV absorbers made of metal oxides and hindered amine light stabilizers. The ultraviolet absorber is contained in a proportion of 0.1 to 10 parts by weight with respect to the weight of the protective layer, and the hindered amine light stabilizer is 0. 0 with respect to the weight of the protective layer. The decorative sheet is contained in a proportion of 1 to 20 parts by weight.
According to the second aspect of the present invention, at least a transparent or translucent thermoplastic resin layer is laminated between the base sheet and the protective layer, and the thermoplastic resin layer includes a triazine ultraviolet absorber, benzotriazole. The cosmetic according to claim 1, comprising at least one ultraviolet absorber selected from the group consisting of inorganic ultraviolet absorbers composed of inorganic ultraviolet absorbers and metal oxides, and hindered amine light stabilizers. It is a sheet.
The invention according to claim 3 is the decorative sheet according to claim 1 or 2, wherein a pattern layer is provided on the base sheet.
The invention according to claim 4 is the decorative sheet according to claim 2 or 3, wherein the thermoplastic resin layer is provided on the base sheet via an adhesive resin layer. is there.
The invention according to claim 5 is the decorative sheet according to any one of claims 2 to 4, wherein the thermoplastic resin layer is a polyolefin resin.

According to the invention of the decorative sheet according to claim 1, protection comprising a crosslinked polyurethane resin having a transparent or translucent crosslinking density of 1.0 to 2.0 (mmol / CC) on the base sheet. At least one layer selected from the group consisting of a triazine-based UV absorber, a benzotriazole-based UV absorber, and an inorganic UV absorber made of a metal oxide, and a hindered amine. A light stabilizer, and the ultraviolet absorber is contained in a proportion of 0.1 to 10 parts by weight with respect to the weight of the protective layer, and the hindered amine light stabilizer is in the weight of the protective layer. against, because it is characterized in that included in a proportion of 0.1 to 20 parts by weight, excellent weather resistance have a sufficient UV-absorbing ability, and withstand the surface Buri It is possible to provide a decorative sheet which is excellent in out resistance and stain resistance.

  According to the invention of the decorative sheet according to claim 2, at least a transparent or translucent thermoplastic resin layer is laminated between the base sheet and the protective layer, and the thermoplastic resin layer is a triazine-based material. Since it is characterized by containing at least one ultraviolet absorber selected from the group consisting of an ultraviolet absorber, a benzotriazole ultraviolet absorber and an inorganic ultraviolet absorber made of a metal oxide, and a hindered amine light stabilizer. The weather resistance can be further improved.

  Moreover, according to the invention of the decorative sheet according to claim 3, since the pattern layer is provided on the base sheet, it is possible to provide a decorative sheet having high design properties.

  According to the decorative sheet invention of claim 4, the thermoplastic resin layer is provided on the base sheet via an adhesive resin layer. Decorative sheet with high strength is obtained.

  According to the invention of the decorative sheet according to claim 5, since the thermoplastic resin layer is a polyolefin resin, a decorative sheet having a low environmental load is provided without using a vinyl chloride resin. It becomes possible to do.

  Hereinafter, the decorative sheet of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a schematic sectional configuration of a decorative sheet according to the present invention. The decorative sheet is provided with a pattern layer 5, an adhesive layer 4, an adhesive resin layer 3, a thermoplastic resin layer 2, and a protective layer 1 sequentially laminated on one surface side of the base sheet 6. A primer layer 7 is laminated on the other surface side of the base sheet 6. Note that the decorative sheet shown in the figure shows an example of the present invention, and is not necessarily limited to such a configuration.

  As the base sheet 6, paper such as thin paper, titanium paper, resin-impregnated paper, polyolefin resin such as polyethylene, polypropylene, polyolefin-based thermoplastic elastomer, polystyrene, polycarbonate, polyester, polyamide, ethylene-vinyl acetate copolymer , Polyvinyl alcohol, acrylic resin, or a sheet made of a foam of these resins, ethylene-propylene copolymer rubber, ethylene-propylene-diene copolymer rubber, styrene-butadiene copolymer rubber, styrene-isoprene-styrene block copolymer Arbitrary ones can be selected from polymer rubber, styrene-butadiene-styrene block copolymer rubber, sheets made of rubber such as polyurethane, and the like.

  In the base material sheet 6, in order to improve machinability, an organic component filler, an inorganic filler, or the like may be added. For example, examples of the organic component filler include urethane crosslinked particles, acrylic crosslinked particles, melamine resin, and natural collagen. Examples of the inorganic filler include alumina, silica, silicon nitride, silicon carbide, glass beads, aluminum hydroxide, calcium carbonate and the like, which are constituent materials of general topcoat agents. Moreover, the resin which comprises a base material sheet has transparency, The pigment etc. for giving concealment property to a sheet | seat may be added.

  The primer layer 7 is provided on the surface of the base sheet 6 opposite to the surface on which the transparent or translucent thermoplastic resin layer 2 is provided. The primer layer 7 is composed of a conventionally known easy-adhesive primer agent mainly composed of, for example, a urethane resin, an acrylic resin, an ethylene-vinyl acetate resin, a polyester resin, or the like. If an inorganic fine powder such as silica is added to the primer layer 7 and the surface thereof is roughened, it becomes difficult for blocking to occur during winding and storage of the decorative sheet, and further adhesion due to the anchoring effect. The improvement of the property will be achieved.

  The pattern layer 5 is provided on one side of the base sheet 6 having such a configuration. As the form of the picture layer 5, it is a layered pattern with a predetermined picture shape, a solid pattern on the entire surface, or a combination of a pattern-shaped part and a solid-shaped part as appropriate. There is something that has become.

  A printing ink is mentioned as a formation material of the pattern layer 5 which becomes such a structure. The printing ink is obtained by adding a colorant such as a pigment and a dye, an extender pigment, a solvent, and various additives into a binder. Examples of the binder include resins such as nitrified cotton, cellulose, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral, polyurethane, acrylic, and polyester, and modified products thereof. One or several of these may be selected and used in combination, and these may be aqueous, solvent-based, or emulsion-based, and even one-component type or two-component using a curing agent. It may be of a type. Furthermore, as the curing type, a type that cures by irradiation with active energy rays such as ultraviolet rays and electron beams, and a type that is isocyanate cured with a urethane-based one can be used. Among the types in which the formed thin film is cured by irradiation with active energy rays such as ultraviolet rays and electron beams, those cured with electron beams are more easily cured in the thickness direction than those cured with ultraviolet rays and are preferably used. .

  Examples of the pigment include condensed azo, insoluble azo, quinacridone, isoindoline, anthraquinone, imidazolone, cobalt, phthalocyanine, carbon, titanium oxide, iron oxide, mica and the like.

  Examples of the method for providing the pattern layer 5 include gravure printing, offset printing, screen printing, flexographic printing, electrostatic printing, and ink jet printing. When a solid pattern layer is provided, a coating method such as a comma coater, a knife coater, or a lip coater, or a metal vapor deposition method or a sputtering method may be used. In selecting the material for forming the pattern layer, the adhesiveness with other layers adjacent to the pattern layer should be sufficiently considered.

  In addition, the ink for obtaining the pattern layer formed in a solid shape may be basically the same as the ink used for forming the pattern layer in the pattern shape, but the material composition thereof may be the same. When the layer needs to be concealed, an opaque pigment, titanium oxide, iron oxide or the like may be used as the pigment to be included. Further, fine powder made of metal such as gold, silver, copper, and aluminum may be used to provide concealment. Among these, flaky aluminum can be preferably used. The thickness of the solid pattern layer formed mainly for concealment is preferably about 2 to 10 μm. When the thickness is less than 2 μm, it is difficult to impart concealability, and when it exceeds 10 μm, the cohesive force of the layer becomes weak.

  A transparent or translucent thermoplastic resin layer 2 is laminated on such a pattern layer 5 via an adhesive layer 4 and an adhesive resin layer 3 described later.

  The resin material used as one of the constituent materials of the thermoplastic resin layer 2 includes polyolefin resins such as polyethylene, polypropylene, polyolefin thermoplastic elastomer, polystyrene, polycarbonate, polyester, polyamide, and ethylene-vinyl acetate copolymer. In addition, known thermoplastic resins such as polyvinyl alcohol can be mentioned, and among them, polyolefin resins can be preferably used. Of the polyolefin resins, polypropylene is also preferably used. More specifically, it is a homopolymer, ie, a homopolymer or a binary or ternary random polymer copolymer copolymerized with ethylene, butene or the like.

  In particular, the use of highly crystallized polypropylene is preferred when it is desired to give the decorative sheet superior surface strength. It is possible to add other resins to this highly crystallized polypropylene. However, when it is desired to provide post-processing suitability such as bending, sufficient attention should be paid to the compatibility with the highly crystallized polypropylene resin. Should.

  The thermoplastic resin layer 2 in the present invention has a role of improving weather resistance, and an ultraviolet absorber and a hindered amine light stabilizer are appropriately added. As the ultraviolet absorber, a triazine ultraviolet absorber, a benzotriazole ultraviolet absorber, or an inorganic ultraviolet absorber made of a metal oxide can be used alone or in combination.

  Examples of the triazine ultraviolet absorber include 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-[(hexyl) oxy] -phenol, 2- [4-[(2- Hydroxy-3-dodecyloxypropyl) oxy] -2-hydroxyphenyl] -4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine, 2- [4-[(2-hydroxy- 3-tridecyloxypropyl) oxy] -2-hydroxyphenyl] -4,6-bis (2,4dimethylphenyl) -1,3,5-triazine, 2,4-bis (2,4-dimethylphenyl) -6- (2-hydroxy-4-iso-octyloxyphenyl) -s-triazine, 2- [4,6-bis (2,4-dimethylphenyl) 1,3,5-triazin-2-yl]- 5- (Oct Oxy) phenol and the like, and mixtures thereof, modified products, polymers, derivatives. One or more of these may be selected and used.

  The amount of the triazine-based ultraviolet absorber added in the thermoplastic resin layer 2 is preferably 0.1 parts by weight or more with respect to 100 parts by weight of the thermoplastic resin. When the addition amount is less than 0.1 parts by weight, there may be a case where sufficient ultraviolet absorbing ability cannot be exhibited in the thermoplastic resin layer. The upper limit of the addition amount of the triazine-based ultraviolet absorber is preferably 1 part by weight or less.

  On the other hand, as the benzotriazole ultraviolet absorber, 2- (2H-benzotriazol-2-yl) -p-cresol, 2- (2H-benzotriazol-2-yl) -4-6-bis (1-methyl) -1-phenylethyl) phenol, 2- [5-chloro (2H) -benzotriazol-2-yl] -4-methyl-6- (tert-butyl) phenol, 2- (2H-benzotriazol-yl)- 4,6-di-tert-pentylphenol, 2- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol, mixtures thereof, modified products, polymerization Products and derivatives. One or more of these may be selected and used.

  The addition amount of these benzotriazole-based ultraviolet absorbers in the thermoplastic resin layer 2 is preferably 0.1 to 1.0 part by weight with respect to 100 parts by weight of the thermoplastic resin. When the addition amount is less than 0.1 parts by weight, there may be a case where sufficient ultraviolet absorbing ability cannot be exhibited in the thermoplastic resin layer. Moreover, when exceeding 1.0 weight part, the adhesive strength with the other layer adjacent to a thermoplastic resin layer, for example, the protective layer 1 to show in figure, may fall.

  Examples of inorganic ultraviolet absorbers made of metal oxides include anatase-type titanium oxide ultrafine particles, rutile-type titanium oxide ultrafine particles, zinc oxide ultrafine particles, cerium oxide ultrafine particles, and mixtures thereof. A material having an energy difference in the band gap of the conduction band equivalent to that in the ultraviolet region of radiation can be used.

Inorganic ultraviolet absorbers made of these metal oxides are suitable because the smaller the primary particle diameter, the less the scattering and the more transparent the light in the visible light region. Conversely, when the primary particle size is increased, it becomes opaque to light in the visible light region, but when the particle size approaches the wavelength in the ultraviolet light region, a scattering effect works and the ultraviolet shielding effect is improved. Therefore, the primary particle size of the inorganic ultraviolet absorbent made of the metal oxide to be added is preferably in the range of 10 nm to 400 nm in consideration of transparency, weather resistance, ultraviolet absorption ability and the like required for the decorative sheet. . The addition amount of the inorganic ultraviolet absorber in the thermoplastic resin layer 2 is preferably 0.1 to 1 part by weight with respect to 100 parts by weight of the thermoplastic resin.
In addition, the total amount of the ultraviolet absorber in the thermoplastic resin layer 2 is preferably 1 part by weight or less with respect to 100 parts by weight of the thermoplastic resin.

  In the thermoplastic resin layer 2, as described above, at least one of a triazine-based or benzotriazole-based ultraviolet absorber and an inorganic ultraviolet absorber made of a metal oxide is used alone or in combination as an ultraviolet absorber. While being added, a hindered amine light stabilizer is added.

  Examples of hindered amine light stabilizers include dimethyl succinate 1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine, poly [{6- (1,1,3,3 -Tetramethylbutyl) amino-1,3,5-triazine-2,4diyl} {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {(2,2,6,6 -Tetramethyl-4-piperidyl) imino}], N, N′-bis (3-aminopropyl) ethylenediamine · 2,4-bis [N-butyl-N- (1,2,2,6,6-pentamethyl) -4 piperidyl) amino] -6-chloro-1,3,5-triazine, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, 2- (3,5-di-t-butyl -4-hydroxybenzyl) 2-n-butylmalonate bis (1,2,2,6,6-pentamethyl-4-piperidyl), tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) 1,2,3 , 4-butanetetracarboxylate and the like. One or several of these are selected and used together with the above-described ultraviolet absorber. The addition amount of the hindered amine light stabilizer in the thermoplastic resin layer 2 is preferably 0.1 to 2 parts by weight with respect to 100 parts by weight of the thermoplastic resin.

  Further, in the thermoplastic resin layer 2, in addition to the ultraviolet absorber and the light stabilizer described above, an antioxidant, a heat stabilizer, a flame retardant, an anti-blocking agent, a catalyst accelerator, a colorant, A light scattering agent, a gloss adjusting agent, and the like for translucency can be appropriately added within a range that maintains transparency or translucency.

  Examples of the antioxidant include various antioxidants such as phenol, sulfur and phosphorus. These antioxidants can be combined with other additives in any combination, but bleed out to the surface of the thermoplastic resin layer by adding a large amount, added colorant, ultraviolet absorber, light stabilizer, etc. It is necessary to pay close attention to synergy and antagonism.

  Examples of the heat stabilizer include hindered phenols, sulfurs, and fertilizer resins, and examples of the flame retardant include aluminum hydroxide and magnesium hydroxide. An example of the quencher is a Ni chelate type. In addition to inorganic UV absorbers made of metal oxides, triazine UV absorbers, and benzotriazole UV absorbers, bezoate, benzophenone, salicylate, and cyanoacrylate UV absorbers should be added as appropriate. Is also possible.

  Furthermore, in consideration of imparting machinability to the thermoplastic resin layer 2 and improving other physical properties, a filler component may be added in addition to the above-described resins and additives. As this filler, organic crosslinked fillers such as urethane crosslinked particles, acrylic crosslinked particles, melamine resin, natural collagen, and alumina, silica, silicon nitride, which are also used as component materials for general topcoat agents, Examples thereof include inorganic fillers such as silicon carbide, glass beads, aluminum hydroxide, and calcium carbonate.

  A known forming method can be used for forming the thermoplastic resin layer 2. For example, an extrusion method or a multilayer coextrusion method performed simultaneously with the formation of an adhesive resin layer described later can be applied. As for the thickness of the thermoplastic resin layer 2, 30-200 micrometers is preferable.

  The adhesive resin layer 3 is not necessary when the adhesive strength between the thermoplastic resin layer 2 and the adhesive layer 4 described later is sufficiently obtained. However, when a non-polar resin such as polypropylene is used as the resin constituting the thermoplastic resin layer 2, the adhesive strength between the thermoplastic resin 2 and the adhesive layer 4 cannot be sufficiently obtained. In such a case, it is recommended to provide the adhesive resin layer 3. The adhesive resin layer 3 is made of, for example, a resin such as polypropylene, polyethylene, or acrylic that has been subjected to acid modification. The thickness is preferably 2 μm or more from the viewpoint of improving adhesiveness, but if it is too thick, the flexibility of the adhesive resin layer itself affects the surface hardness, or conversely, the adhesive strength is lowered from the viewpoint of cohesion and heat resistance. Therefore, the upper limit is preferably about 20 μm. In addition, as a method for forming the adhesive resin layer, in consideration of an improvement in adhesive strength, lamination by a coextrusion method with the thermoplastic resin layer 2 is preferable.

  On the other hand, the adhesive layer 4 is a layer provided to improve the adhesive strength between adjacent layers, that is, the pattern layer 5 and the adhesive resin layer 3. As a constituent material of the adhesive layer 4, a known adhesive material can be used as long as sufficient adhesive strength can be obtained. For example, acrylic, polyester, polyurethane, and epoxy adhesive materials can be used. Among them, a two-component curing type polyurethane adhesive material having a high coating cohesive force can be preferably used. Further, the coating method can be appropriately selected depending on the coating liquid viscosity of the adhesive material and the like, but in general, the dry coating method using a gravure plate can be said to be a preferable method from the viewpoint of low coating amount management. The coating amount may be appropriately determined in consideration of adhesive strength, cost, etc., but a coating amount as low as possible is preferable.

  The adhesive layer 4 is formed on the pattern layer 5 and is integrally formed with the thermoplastic resin layer 2 and the adhesive resin layer 3. Although the formation method depends on the adhesive resin layer 3 adjacent thereto, it may be formed by extrusion lamination, dry lamination or the like according to the characteristics of the material.

  Next, the protective layer 1 provided on the decorative sheet surface will be described. The protective layer 1 is a layer provided for protecting the thermoplastic resin and the pattern layer from being deteriorated by ultraviolet rays, improving the stain resistance, and further adjusting the gloss of the surface, and is a crosslinked resin material. And a protective layer forming material containing an ultraviolet absorber, a light stabilizer and the like. Examples of main constituent materials include polyurethane, acrylic silicon, fluorine, epoxy, vinyl, polyester, melamine, aminoalkyd, and urea resin materials. The form of the material for forming the protective layer mainly composed of these resins may be any of water, emulsion, solvent, etc., and the curing type is a one-component type or a two-component type using a curing agent. But you can. Among these, a protective layer mainly composed of a urethane-based resin using isocyanate can be said to be desirable from the viewpoints of workability in formation, cost, cohesion of the resin itself, and the like.

  Examples of the isocyanate described above include tolylene diisocyanate (TDI), xylylene diisocyanate (XDI), hexamethylene diisocyanate (HMDI), metadiisocyanate (MDI), lysine diisocyanate (LDI), isophorone diisocyanate (IPDI), and methylhexane diisocyanate (HTDI). ), Methylcyclohexanone diisocyanate (HXDI), trimethylhexamethylene diisocyanate (TMDI), etc., and an appropriate one can be selected from these, but considering the weather resistance, it is more straightforward than the type having a double bond. A type having a chain structure, particularly hexamethylene diisocyanate (HMDI) is preferred. Further, in order to further improve the surface hardness, it is possible to use a resin that is cured by an active energy ray such as an ultraviolet ray or an electron beam. In addition to the single use, the combined use of the thermosetting type and the photocuring type hybrid curing type may be effective from the viewpoint of surface hardness, curing shrinkage, adhesion and the like.

  As a protective layer in a conventional decorative sheet, a resin having a low crosslinking density with a crosslinking density of about 0.5 (mmol / CC) has been often used from the viewpoint of cost, application range, and processability. In order to improve the weather resistance, ultraviolet protective agents such as triazine, benzophenone, and benzotriazole are added to these protective layers. However, the UV absorber added to the resin with low crosslink density is reduced by bleed out due to exposure to external heat, light, rain, etc. As a result, the protective layer and the thermoplastic resin layer and the printing layer laminated under the protective layer have deteriorated. In addition, triazine-based ultraviolet absorbers have high weather resistance even when added in a low amount. However, the triazine-based ultraviolet absorber easily bleeds out due to a compatibility problem with the resin, and it has not been possible to secure weather resistance that can withstand architectural exterior use.

  In contrast, in the present invention, the protective layer 1 has a transparent or translucent crosslink density of 0.8 to 2.0 (mmol / CC), more preferably 1.0 to 2.0 (mmol / CC). By using a resin with a high cross-linking density, it is possible to provide a decorative sheet excellent in weather resistance having sufficient UV absorbing ability by reducing bleeding of the UV absorber added in the protective layer. Further, by using a resin having a high crosslinking density, it has become possible to provide a decorative sheet having improved flaw resistance and contamination resistance on the decorative sheet surface. When the crosslink density is less than 0.8 (mmol / CC), the protective layer becomes too soft, inferior in scratch resistance and contamination resistance, and bleed out of the UV absorber is likely to occur, and 2.0 (mmol / CC). ) Greater than, it becomes too hard and inferior in workability.

The crosslink density according to the present invention is determined by the following method. Using a forced stretching vibration type viscoelasticity measuring device, a dynamic elastic modulus (E ′) at the time of temperature increase was obtained, and calculated from the temperature at which E ′ was minimized and the minimum value by the following equation. The measurement frequency was 10 Hz.
E '= 3nRT
E ′: storage elastic modulus (dyne / cm ² ), n: crosslink density (mol / CC), R: gas constant (8.314 × 10 ⁷ , erg.deg / mol) T: absolute temperature (° K) is there.
When the molecular weight between cross-linking points is small and the number of cross-linking points is large, the storage elastic modulus is high and the cross-linking density is high. Therefore, the crosslinking density of the protective layer 1 varies depending on the combination of the type and amount of the crosslinking agent, the molecular weight of the resin to be crosslinked, the number of functional groups, and the like. In order to increase the crosslinking density of the resin of the protective layer 1, the molecular weight of the resin to be used is decreased, the number of functional groups of the resin to be crosslinked is increased, and the addition amount of the crosslinking agent is increased. Density increases.

  An ultraviolet absorber and a hindered amine light stabilizer are appropriately added to the protective layer 1. As the ultraviolet absorber, a triazine ultraviolet absorber, a benzotriazole ultraviolet absorber, and an inorganic ultraviolet absorber made of a metal oxide can be suitably used.

  Examples of the triazine-based ultraviolet absorber added to the protective layer 1 include 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-[(hexyl) oxy] -phenol, 2 -[4-[(2-hydroxy-3-dodecyloxypropyl) oxy] -2-hydroxyphenyl] -4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine, 2- [ 4-[(2-hydroxy-3-tridecyloxypropyl) oxy] -2-hydroxyphenyl] -4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine, 2- (2 Hydroxy-4- [1-octyloxycarbonylethoxy] phenyl) -4,6-bis (4-phenylphenyl) -1,3,5-triazine, 2,4-bis (2,4-dimethylphenyl) -6 − ( - hydroxy-4-iso - octyloxyphenyl) -s-triazine, and mixtures thereof, modified products, polymers, derivatives and the like. These can be used alone or in combination.

  Moreover, as a benzotriazole type ultraviolet absorber added to the protective layer 1, 2- (2H-benzotriazol-2-yl) -p-cresol, 2- (2H-benzotriazol-2-yl) -4- 6-bis (1-methyl-1-phenylethyl) phenol, 2- [5-chloro (2H) -benzotriazol-2-yl] -4-methyl-6- (tert-butyl) phenol, 2- (2H -Benzotriazol-yl) -4,6-di-tert-pentylphenol, 2- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol and the like A mixture, a modified product, a polymerized product, and a derivative thereof can be exemplified. These can also be used alone or in combination.

  Examples of inorganic ultraviolet absorbers composed of metal oxides added to the protective layer 1 include anatase-type titanium oxide ultrafine particles, rutile-type titanium oxide ultrafine particles, zinc oxide ultrafine particles, cerium oxide ultrafine particles, and mixtures thereof. A semiconductor whose energy difference between the band gap of the valence band and the conduction band is equivalent to that in the ultraviolet region of radiation can be used.

  The smaller the primary particle diameter of the inorganic ultraviolet absorber made of a metal oxide, the smaller the scattering, and the more transparent the light in the visible light region is. Conversely, when the primary particle size is increased, it becomes opaque to light in the visible light region, but when the particle size approaches the wavelength in the ultraviolet region, a scattering effect is activated and the ultraviolet shielding effect is improved. The primary particle diameter of the inorganic ultraviolet absorbent made of a metal oxide to be actually added may be appropriately set in consideration of transparency, weather resistance, ultraviolet absorbing ability and the like required for a decorative sheet.

  Further, as described above, at least one selected from a triazine ultraviolet absorber, a benzotriazole ultraviolet absorber and an inorganic ultraviolet absorber made of a metal oxide is added to the protective layer 1 as described above. In addition, a hindered amine light stabilizer is added.

The hindered amine light stabilizer added to the protective layer 1 is bis (1,2,2,6,6-pentamethyl-4-piperidinyl) [[3,5-bis (1,1-dimethylethyl) -4. -Hydroxyphenyl] methyl] butyl malonate, bis (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, methyl (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, Examples include decanedioic acid bis [2,2,6,6-tetramethyl-1-octyloxy) -4-piperidinyl] ester and the like, mixtures, modified products, polymers, derivatives and the like thereof. These can also be used alone or in combination. The amount of the hindered amine light stabilizer added to the protective layer 1 is preferably 0.1 to 20 parts by weight with respect to the weight of the protective layer 1. Further, the amount of the triazine-based ultraviolet absorber added to the protective layer 1 is preferably 0.1 to 10 parts by weight with respect to the weight of the protective layer 1. The amount of the benzotriazole-based ultraviolet absorber added to the protective layer 1 is preferably 0.1 to 10 parts by weight with respect to the weight of the protective layer 1. The amount of the inorganic ultraviolet absorber added to the protective layer 1 is preferably 0.1 to 10 parts by weight with respect to the weight of the protective layer 1.
The total amount of the ultraviolet absorber in the protective layer 1 is preferably 10 parts by weight or less with respect to the weight of the protective layer 1.

  Moreover, in order to provide various functions, you may add functional additives, such as an antibacterial agent, a fungicide, and a flame retardance, in this protective layer. Furthermore, inorganic fillers such as alumina, silica, silicon nitride, silicon carbide, glass beads, etc. can be added for imparting design properties to the surface, adjusting gloss, and improving wear resistance.

  As the flame retardant, aluminum hydroxide, magnesium hydroxide, Ni chelate as a quencher, or the like can be added in any combination. In addition to the triazine-based or benzotriazole-based UV absorber, a benzoate-based, benzophenone-based, salicylate-based, cyanoacrylate-based, or the like can be added in combination as the UV absorber. Specific examples include benzophenone-based octabenzone, modified products, polymers, and derivatives thereof.

  Since especially the protective layer 1 is located in the outermost surface, it is a part which has a great influence on provision of the weather resistance of a decorative sheet. Therefore, it is necessary to fully consider weather resistance, and the amount of functional additive added depends on the solubility in the resin and solvent constituting the protective layer-forming material (coating solution), but it depends on the required physical properties and addition of a large amount. Considering the adverse effects, it is preferable that the amount is in the range of about 0.1 to 10 parts by weight with respect to 100 parts by weight of the solid content of the protective layer forming material.

  Also, the method for forming the protective layer may be selected according to the properties, viscosity, coating amount, etc. of the material for forming the protective layer, and it is not necessary to adopt a special coating method. Specifically, it may be provided by a general coating method such as gravure coating, micro gravure coating, comma coating, lip coating or the like. Further, an uneven embossed pattern may be applied to improve the design. Moreover, it is preferable that it is 1-20 micrometers as a film thickness of a protective layer.

  In the case of applying an embossed pattern, there are a method in which each layer is once laminated by various methods and then embossed by hot pressure, a method in which an uneven pattern is provided on a cooling roll and embossed simultaneously with extrusion lamination. In addition, there is a method in which a transparent resin layer and a base sheet that are simultaneously embossed at the time of extrusion are bonded together by heat or dry lamination. Further, ink or resin may be embedded in the embossed recesses, and the ink or resin in the recesses may be transferred to improve the design and weather resistance.

  The term “transparent or translucent” as used in the present invention means that the total light transmittance defined in JIS K7105 is 75% or more.

  EXAMPLES Hereinafter, although an Example and a comparative example further demonstrate this invention, this invention is not restrict | limited to the following example.

Example 1
First, as a thermoplastic resin layer forming material, a benzotriazole-based ultraviolet absorber 2- [5-chloro (2H) -benzotriazol-2-yl] -4-methyl is used with respect to 100 parts by weight of a homotype polypropylene resin for extrusion molding. 0.5 parts by weight of -6- (tert-butyl) phenol, hindered amine light stabilizer (poly [{6- (1,1,3,3-tetramethylbutyl) amino-1,3,5- Triazine-2,4diyl} {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}]). A resin to which 0.5 part by weight of phenol-based antioxidant (Irganox 1010: manufactured by Ciba Specialty Chemicals Co., Ltd.) was added was used.

  Next, a pattern layer with a wood grain pattern is provided on the surface of a base material sheet (thickness 120 μm) made of polyethylene, and an adhesive layer having a thickness of about 2 μm made of a two-component curable urethane resin adhesive is provided thereon. A base sheet made of polyethylene was prepared.

  Subsequently, a polypropylene acid-modified resin was used as the adhesive resin layer forming material, and the resin composition was used as the thermoplastic resin layer forming material, and melt extrusion was performed with an extruder. On the adhesive layer of the material sheet, an adhesive resin layer and a thermoplastic resin layer were formed by a multilayer extrusion lamination method. At this time, the thicknesses of the formed adhesive resin layer and thermoplastic resin layer were 10 μm and 80 μm, respectively.

The surface of the thermoplastic resin layer of the multilayer sheet obtained in the above step is subjected to corona discharge treatment, and a triazine ultraviolet absorber (2- [4-[(2-hydroxy-3-tridecyloxypropyl) oxy] -2 -Hydroxyphenyl] -4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine) and a hindered amine light stabilizer (bis (1,2,2,6,6-pentamethyl-4- containing piperidinyl) sebacate and methyl (1,2,2,6,6-pentamethyl-4-piperidinyl) mixtures sebacate), two-component curing were prepared to crosslink density is 1.7 (m mol / CC) A type urethane topcoat agent was dry coated to provide a protective layer to produce a decorative sheet according to Example 1 of the present invention. Triazine-based UV absorber and hindered amine light stabilizer, the weight of the protective layer against was added so that the respective 5 parts by weight and 5 parts by weight.

Comparative Example 1
In Example 1, as the material of the protective layer, the same triazine-based UV absorber and hindered amine light stabilizer as in Example 1 were prepared so as to have a crosslinking density of 0.5 ( m mol / CC) containing the same amount. A decorative sheet according to Comparative Example 1 for comparison was prepared using a two-component curable urethane-based topcoat agent and the other materials and production methods similar to those of Example 1.
In addition, the coating agent with a high crosslinking density of Example 1 and the coating agent with a low crosslinking density of the comparative example 1 were prepared by changing the addition amount of a crosslinking agent.

<Performance comparison>
For each decorative sheet of Example 1 and Comparative Example 1 produced as described above, a weathering accelerated test (metal halide lamp type tester JTM G 01 2000 Japan Testing Machine Industry Association Standard) was performed in order to evaluate the weather resistance. . As a tester, a die plastic metal weather (KU-R5CI-A: manufactured by Daipura Wintes Co., Ltd.) was used.
The weathering acceleration test conditions were as follows.
[1] Light source lamp: MW-60W, filter: KF-1 (irradiation range 295 nm to 780 nm), illuminance 65 ± 3 mW / cm ² (measurement range 330 nm to 390 nm)
[2] Light (irradiation) (53 ° C, 50% RH) 20.00 hours [3] Dew (dark condensation) (30 ° C, 98% RH) 4.00 hours [4] Rest (rest) (30 ° C, 98% RH) 0.01 hours

  A 240 hour test was conducted with the 24.01 hour cycle shown above as one cycle. The shower was performed for 30 seconds before and after Dew.

  About the decorative sheet of Example 1 and Comparative Example 1 in which the weather resistance acceleration test was performed, the adhesion of the protective layer was evaluated by a method without cross-cut according to JISK5600-5-6. The evaluation is shown in Table 1.

  Moreover, about the decorative sheet of Example 1 and Comparative Example 1 before and after the weathering acceleration test, the peeling solvent was allowed to act to forcibly peel off the protective layer and the thermoplastic resin layer together, and the peeled protection The transmittance of ultraviolet rays at 340 nm of the layer and the thermoplastic resin layer was measured. A difference in ultraviolet transmittance before and after the weathering acceleration test (transmittance after the weathering acceleration test−transmittance before the weathering acceleration test) was calculated, and a decrease in the ultraviolet absorption ability was evaluated. If the ultraviolet absorption ability decreases, the value of the difference in transmittance increases. The results are shown in Table 1.

  From the above results, the decorative sheet of the present invention has a reduced decrease in the adhesion of the protective layer after the weather resistance test, and the ultraviolet rays of the protective layer and the thermoplastic resin layer as compared with the decorative sheet prepared for comparison. It was found that the decrease in shielding and absorption ability was suppressed.

  The decorative sheet of the present invention is a decorative sheet used as a construction material such as an interior / exterior member for construction, a fitting, a frame material, a flooring material, or a surface material for home appliances, in particular, a wooden board, an inorganic board, a metal plate. It is useful for a decorative sheet used when a decorative board is produced by laminating to a sheet, etc., and the weather resistance can sufficiently satisfy the weather resistance required for a surface material of a building material for exterior use. .

It is a schematic sectional drawing of an example of the decorative sheet of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Protective layer 2 ... Thermoplastic resin layer 3 ... Adhesive resin layer 4 ... Adhesive layer 5 ... Picture layer 6 ... Base material sheet 7 ... Primer layer

Claims (5)

On the base material sheet, at least a protective layer containing a polyurethane resin cross-linked having a transparent or translucent cross-linking density of 1.0 to 2.0 (mmol / CC) is laminated, Containing at least one ultraviolet absorber selected from the group consisting of triazine-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, and inorganic ultraviolet absorbers composed of metal oxides and hindered amine-based light stabilizers; The agent is included in a proportion of 0.1 to 10 parts by weight with respect to the weight of the protective layer, and the hindered amine light stabilizer is included in a proportion of 0.1 to 20 parts by weight with respect to the weight of the protective layer. A decorative sheet characterized by   A transparent or translucent thermoplastic resin layer is at least laminated between the base sheet and the protective layer, and the thermoplastic resin layer is composed of a triazine ultraviolet absorber, a benzotriazole ultraviolet absorber and a metal oxide. The decorative sheet according to claim 1, comprising at least one ultraviolet absorber selected from the group consisting of inorganic ultraviolet absorbers and a hindered amine light stabilizer.   The decorative sheet according to claim 1, wherein a pattern layer is provided on the base sheet.   The decorative sheet according to claim 2 or 3, wherein the thermoplastic resin layer is provided on the base sheet via an adhesive resin layer.   The decorative sheet according to any one of claims 2 to 4, wherein the thermoplastic resin layer is a polyolefin resin.

Images