JP4428191B2 - Manufacturing method of decorative sheet - Google Patents

Description

  The present invention relates to a decorative sheet mainly made of a polyolefin-based material, among decorative sheets mainly made of a thermoplastic resin, mainly used for surface decorations such as entrance doors and curtain rails of buildings. is there.

  Conventionally, surface decorations mainly for building entrance doors and steel plate exterior parts have been applied by applying a decorative pattern directly to the steel plate member, or by applying a pattern to the surface by printing and applying a texture to the surface. The method of sticking the sheet to the steel plate member has been used, but in any case it is difficult to express a design with a sense of unevenness only by painting, so it is possible to apply concave patterns such as embossed wood grain, stone grain, pear texture, etc. Well done.

  On the other hand, in the field of decorative sheets in recent years, decorative sheets mainly made of polypropylene or acrylic resin that have the same design as polyvinyl chloride decorative sheets and have a low environmental impact have attracted attention. In particular, decorative sheets made of polypropylene resin as the main material tend to be less expensive to manufacture, including raw material costs than when acrylic resin is used, and there is a high market demand for polypropylene-based decorative sheets. . Therefore, there are an increasing number of cases where a polypropylene-based decorative sheet is used for surface decoration of exterior members.

  When polypropylene-based decorative sheets are used for surface decoration of exterior parts, the usage environment is outdoors, so there is a high demand for weather resistance performance, but general polypropylene resins are compared to polyvinyl chloride and acrylic resins. Because the weather resistance is inferior, the polypropylene resin layer is formulated with UV absorbers, light stabilizers, etc., and a surface protective layer is provided, and UV absorbers and light stabilizers are also formulated within it. It has weather resistance that can be used for various purposes.

  However, since the polypropylene resin layer is often provided with a concave pattern such as wood grain, stone grain, and satin, the depth of the concave part is particularly deep in the gravure coating method that is generally used as a method for providing a surface protective layer. In some cases, the surface protective layer is difficult to be laminated up to the recessed portion, and as a result, in an actual use environment, weather resistance deterioration from the recessed portion occurs at a relatively early stage, which causes a deterioration in design. End up.

On the other hand, there is also a method of performing a wiping coat in which a colored resin is embedded in the recessed portion with a wiping doctor blade for the purpose of mainly improving the design property on the surface having the recessed portion. Since the surface portion other than the portion is scraped by the wiping doctor blade, the weather resistance is lowered.
Japanese Patent Laid-Open No. 3-101936

  The present invention has been made in view of the drawbacks of the related art, and the object of the present invention is to provide a polypropylene decorative sheet having weather resistance while maintaining a three-dimensional design feeling due to the concave pattern on the surface. is there.

The present invention has been made in order to solve the above-mentioned problems. That is, the invention of claim 1 includes a base sheet, a concealing pattern layer, and a single-layer or multi-layer transparent polypropylene resin having a concave pattern on the surface. In the method for producing a decorative sheet, in which a surface protective layer comprising at least a surface protective layer (a) and a surface protective layer (b) is laminated in this order , a surface protective agent is applied to the surface of the transparent polypropylene resin layer by gravure coating. A step of forming a surface protective layer (a) by drying and solidifying the surface protective agent applied to the surface of the transparent polypropylene resin layer, and a gravure of the surface protective agent on the surface of the surface protective layer (a) A step of coating by coating, and a surface protective agent applied to the surface of the surface protective layer (a) is embedded in the recessed pattern of the transparent polypropylene resin layer by wiping coating A decorative sheet manufacturing method of which comprises a step of forming the surface protective layer (b) in this order by the.

  According to the first aspect of the present invention, a portion other than the recessed portion is covered with the resin by the first gravure coat, and the recessed portion is filled with the subsequent wiping coat. At this time, the surface portion other than the recessed portion of the polypropylene resin layer Is not scraped by the wiping doctor blade. The wiping coat may be subjected to another gravure coat before that, or may be re-applied after that. By doing in this way, a surface protection layer is formed in the whole surface, and it becomes possible to obtain the polypropylene-type decorative sheet which has a weather resistance, maintaining the three-dimensional design feeling by the surface concave pattern.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a cross-sectional structure of one embodiment of the decorative sheet of the present invention. A base sheet 1, a concealing pattern layer 2, a transparent polypropylene resin layer 3 with a recessed portion, and surface protective layers 4 (a) to 4 (c) are laminated.

  The substrate sheet 1 in the present invention is not particularly limited as long as it is usually used as a substrate of a decorative sheet. However, considering the environmental load, a material other than polyvinyl chloride is preferable. In general, polyolefin resins such as polypropylene and polyethylene are widely used. Other than the above, for example, ethylene vinyl acetate copolymer, ethylene vinyl alcohol copolymer, polystyrene, ABS, polymethyl methacrylate, polymethyl acrylate, polybutyl acrylate, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl acetal , Polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyurethane, polyamide, nylon 6, nylon 66, paper, and the like may be used. If necessary, these materials may be combined to form a multilayer.

  The concealing pattern layer 2 in the present invention is provided for imparting design properties such as a grain pattern, a stone pattern, a sand pattern, an abstract pattern, etc. to the decorative sheet, or for concealing the base material sheet by solid coloring. As a method for forming the concealing pattern layer 2, known methods such as gravure printing, offset printing, intaglio printing, screen printing, flexographic printing, silk printing, electrostatic printing, and ink jet printing are applied to the front surface or the back surface of the base sheet 1 or both. However, the present invention is not necessarily limited to this. Ink used is also known, that is, a colorant such as a dye or pigment, an extender is added to the vehicle, and a plasticizer, stabilizer, wax, grease, desiccant, curing agent, thickener, dispersant. In addition, a filler or the like may be arbitrarily added and sufficiently diluted with a solvent, a diluent or the like and stirred.

  When the T-die extrusion method is used as the manufacturing method of the base sheet 1, the base sheet 1 can be directly colored and extruded to form a masking pattern layer 2 to provide a masking effect. As a coloring method, a dry color method using a fine powdery colorant in which a pigment is treated with a dispersion aid or a surfactant, and a master batch pellet in which a resin and a high-concentration pigment are melt-mixed and pre-dispersed are prepared. However, there is a masterbatch method for dry blending with an ordinary resin not colored in an extrusion hopper, and there is no particular limitation. The types of pigments may be those usually used, but inorganic pigments such as titanium oxide, ultramarine blue, cadmium pigment, iron oxide and the like are particularly desirable in consideration of weather resistance and heat resistance. Also, organic pigments such as phthalocyanine pigments and quinacridone pigments can be used. The color and blending ratio of the pigment are arbitrarily determined in view of the degree of concealment and design properties, and are not particularly limited.

  In addition, as a method of applying the concealing pattern layer 2 to the base sheet 1, master batch pellets obtained by melting and mixing a high concentration pigment in a resin having different flow characteristics from the resin of the base sheet 1, or wood powder There is a method of forming the concealed pattern layer 2 on the base sheet 1 by adding glass powder and the like, and forming the base sheet 1 by extrusion film formation with the resin of the base sheet 1.

  Of course, it is possible to use a plurality of methods for forming the masking pattern layer 2 together. Moreover, as a manufacturing method of the base material sheet 1, the calendar method is generally used, but also in that case, the masking pattern layer 2 can be formed by using substantially the same method.

  The transparent polypropylene resin layer 3 is provided for improving the design properties of the decorative sheet, protecting the masking pattern layer 2, surface abrasion resistance, chemical resistance, scratch resistance, weather resistance, and the like. As a method of laminating the transparent polypropylene resin layer 3, a heat lamination method in which heat and pressure are applied, a dry lamination method and a wet lamination method in which bonding is performed using an adhesive, and a polypropylene resin from a T-die on a base sheet. In addition to the extrusion lamination method in which melt extrusion is performed, there are methods such as a knee lamination method and a sand lamination method. Among these, use the extrusion lamination method when you want to increase the production efficiency of large lots and small varieties, and use the dry lamination method and wet lamination method when you want to produce small lots and many types of products with short indirect time. Is preferred.

  The material of the transparent polypropylene resin layer 3 is not particularly limited, but by using a homopolypropylene having a crystallinity defined by the pentad fraction of 80% or less for the transparent polypropylene resin layer, Whitening and cracking are reduced, the degree of freedom of the bent shape is increased, and a highly designable member can be obtained. In addition, because of the homopolypropylene, the melting point is higher than when using random polypropylene, etc., so that the shape change due to heat of the concave pattern on the decorative sheet surface occurs compared to random type polypropylene. It has the advantage of being difficult. In addition, since it consists essentially of propylene, there is no concern about whitening due to the occurrence of dissociation (crazing) at the interface between rubber and polypropylene, as in the system with a rubber component added.

  In addition, a transparent polypropylene resin layer may be provided as appropriate in order to further improve the design properties of the decorative sheet and impart various physical properties. For example, when laminating a transparent polypropylene resin layer by an extrusion lamination method, a general polypropylene resin does not have a polar group. Therefore, it is possible to develop the adhesive strength of the laminated surface by using a special polyolefin resin with polar groups introduced by unsaturated carboxylic acid such as maleic acid or its anhydride and making it into a multilayer structure. .

  For imparting weather resistance to the decorative sheet, addition of an ultraviolet absorber, a light stabilizer and the like to the transparent polypropylene resin layer 3 is suitably performed. As the ultraviolet absorber, as long as it has a desired ultraviolet absorption effect and does not significantly affect the properties other than the weather resistance of the decorative sheet, there are no particular restrictions on its components and addition amount, for example, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (3-t-butyl-5-methyl-2-hydroxyphenyl) -5 Benzotriazole ultraviolet rays such as chlorobenzotriazole, 2- (3,5-t-butyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (2-hydroxy-5-t-octylphenyl) -benzotriazole Absorbents, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone and other benzophenone purple External line absorbers, triazine ultraviolet absorbers such as 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-[(hexyl) oxy] -phenol, cerium oxide, titanium oxide, etc. It is possible to add one or more of these inorganic ultraviolet absorbers in any combination.

  The light stabilizer is not particularly limited as long as it has a desired ultraviolet absorption effect and does not significantly affect the properties other than the weather resistance of the decorative sheet. For example, 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-4piperidyl) 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 Hindered amines such as 1,2,2,6,6-pentamethyl-4-piperidyl) and tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate Light stabilizers, benzoate light stabilizers such as 2,4-di-t-butylphenyl-3,5-di-t-butyl-4-hydroxybenzoate, bis- (2,2,6,6-tetra It is possible to use one or a combination of one or more of amino ether type light stabilizers such as methyl-1- (octyloxy) -4-piperidinyl) ester.

  In addition, a heat stabilizer, a flame retardant, an antiblocking agent, etc. are added as needed. The heat stabilizer is pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl)]-propionate, 2,4-bis- (n-octylthio) -6- (4- Hydroxy-3,5-di-t-butylanilino) -1,3,5-triazine, octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 1,3,5-trimethyl -2,4,6-tris (3,5-t-butyl-4-hydroxybenzyl) benzene, 1,3,5-tris (4-t-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanur Hindered phenol antioxidants such as acids, 2,2′-methylenebis (4-ethyl-6-tert-butylphenol), 2,2′-methylenebis (4-methyl-6-tert-butylphenol) Can be used in combination with one or more types of phenolic antioxidants such as tri) (phosphorus antioxidants typified by tris (2,4-di-t-butylphenyl) phosphite). It is.

  Examples of the flame retardant include inorganic compounds such as aluminum hydroxide, magnesium hydroxide, calcium carbonate, and magnesium carbonate, and phosphate ester flame retardants, but there are no particular limitations on the components. However, if it is a non-vinyl chloride sheet in consideration of the environment, it is necessary to consider the use of a halogen-based flame retardant.

  As the anti-blocking agent, an inorganic anti-blocking agent such as aluminum silicate, silicon oxide, hydrotalcite and calcium carbonate, an organic anti-blocking agent such as fatty acid amide, and the like are optionally added.

  In order to adjust the three-dimensional effect and surface gloss, the transparent polypropylene resin layer 3 is provided with a concave pattern. The method for applying the concave pattern may be a normal hot-pressure embossing method and is not limited at all. When the T-die extrusion method is used as a method for forming the polypropylene resin layer 3, the surface of the chill roll for cooling and solidifying the molten resin is provided with a pattern in which the concave and convex portions to be imparted to the decorative sheet are opposite to the concave and convex portions. There is a method in which the extruded resin is embossed between a cooling roll and a press roll to form a concave pattern on the surface of the transparent polypropylene resin layer 3.

  Furthermore, surface protective layers 4 (a) to 4 (c) are laminated on the surface layer of the transparent polypropylene resin layer 3 on the side where the recessed pattern is applied. The material of the surface protective layers 4 (a) to 4 (c) should have sufficient physical properties such as scratch resistance, weather resistance, solvent resistance, heat resistance, etc., and sufficient adhesion to the transparent polypropylene layer. Although not particularly defined, a urethane resin having acrylic as a main skeleton is more preferably used. Moreover, the said ultraviolet absorber, a light stabilizer, a heat stabilizer, a flame retardant, an antiblocking agent, etc. are added suitably as an additive.

  In the present invention, as a method of laminating the surface protective layer 4, first, the surface of the transparent polypropylene resin layer 3 is subjected to an oxidation treatment by corona treatment or the like, and is first coated by gravure coating. It is difficult to enter. (4 (a)) Therefore, after the coating surface is once dried and solidified, the surface is scratched again with a doctor blade as a wiping coat after the lamination coating and before the drying treatment, and the resin is filled in the recessed portion. (4 (b)) After drying and solidifying again, it is applied to the entire surface by gravure coating and dried and solidified. (4 (c))

  In addition, in order to improve the adhesion strength between the decorative sheet of the present invention and the wooden boards, inorganic boards, metal plates, etc., a primer layer may be provided on the back surface of the base sheet 1 as necessary. good. With respect to this primer layer, sufficient adhesion strength with the base material has been obtained, and the floating of the sheet between the base material sheet at the time of lamination and the wooden board, inorganic board, metal plate, etc. If it does not occur, it is not particularly specified, but it is preferable to use a polyurethane-based material.

  The decorative plate obtained by adhering the decorative sheet made in this way onto the metal plate has superior weather resistance and processability compared to the conventional one, and is equal to or better than the conventional one. It becomes a decorative board having design properties.

A polypropylene sheet having a thickness of 70 μm was used as a base sheet, and a wooden pattern was applied as a concealing pattern layer by gravure printing.
Next, an isocyanate-curing anchor coating agent (main agent: Takei Mitsui Chemicals Co., Ltd., “Takelac, curing agent: Mitsui Takeda Chemicals Co., Ltd.) with two liquids of a main agent and a hardener on the surface of the polypropylene sheet printed pattern side. "Takenate" manufactured in Japan) using a gravure coating method with a thickness of about 1 µm, and on its surface, maleic acid-modified random polypropylene ("Admer" manufactured by Mitsui Chemicals, Inc.) and pentad fraction A transparent homopolypropylene resin having a crystallinity of 70% (“Idemitsu TPO” manufactured by Idemitsu Kosan Co., Ltd.), 0.5 parts by weight of a hindered amine light stabilizer and a benzotriazole ultraviolet absorber 0 .5 parts by weight of each resin added in this order by a T-die coextrusion lamination method so that the thickness ratio is 10:90. It was laminated. In addition, the cooling roll at the time of co-extrusion lamination was provided with a pattern in which the concave and convex portions to be imparted to the decorative sheet were opposite to each other, and a concave pattern was applied to the laminated transparent polypropylene resin.

  A two-component curable urethane system in which a hindered amine light stabilizer and a benzotriazole ultraviolet absorber are added as a surface protective layer to the outermost surface of the sheet after corona treatment is applied to the concave pattern side of the transparent polypropylene resin. A surface protective agent (“UC Clear” manufactured by Dainippon Ink & Chemicals, Inc.) is laminated by a gravure coating method to a thickness of about 3 μm (dry), dried and solidified, and then again laminated at a thickness of 6 μm (wet) as described above. The surface protective agent was embedded in the recessed pattern portion. After drying and solidifying again, the same surface protective agent as described above was laminated on the entire surface by a gravure coating method to a thickness of about 6 μm (dry) and solidified by drying to obtain a decorative sheet. This was bonded to a steel plate substrate using an olefin / steel plate adhesive (“Hybon” manufactured by Hitachi Chemical Polymer Co., Ltd.) to obtain a decorative plate.

<Comparative Example 1>
After applying corona treatment to the concave pattern side of the transparent polypropylene resin layer, a decorative board was obtained in the same procedure as in Example 1 except that the wiping coating was directly performed without performing the gravure coating before the wiping coating. It was.

<Comparative example 2>
A decorative board was obtained in the same procedure as in Example 1 except that wiping coating was not performed.

<Performance comparison>
The decorative plates of Examples 1 to 3 and Comparative Example 1 obtained as described above were evaluated for weather resistance and bending workability. The results are shown in Tables 1 and 2 below.

  As can be seen from the results of Table 1, the surface of the transparent polypropylene resin layer was not scraped in the decorative board of Example 1 as compared with the decorative board of Comparative Example 1, that is, the decorative board that was first subjected to wiping coating. Therefore, the weather resistance performance was excellent. Moreover, since the surface protection agent was embedded also into the recessed part compared with the decorative board of the comparative example 2, and the decorative board which did not perform wiping coating, it resulted in the weather resistance performance being excellent.

It is explanatory drawing which shows the cross-section of one Example of the decorative sheet in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Base material sheet 2 ... Concealment pattern layer 3 ... Transparent polypropylene resin layer 4 (a) ... Surface protective layer (gravure coat method)
4 (b) ... Surface protective layer (wiping coat method)
4 (c) Surface protective layer (gravure coating method)

Claims (1)

A base sheet, a concealing pattern layer, a single-layer or multiple-layer transparent polypropylene resin layer having a concave pattern on the surface, and a surface protective layer comprising at least a surface protective layer (a) and a surface protective layer (b) are laminated in this order. In the method for producing a decorative sheet,
Applying a surface protective agent to the surface of the transparent polypropylene resin layer by gravure coating;
Forming the surface protective layer (a) by drying and solidifying the surface protective agent applied to the surface of the transparent polypropylene resin layer;
Applying a surface protective agent to the surface of the surface protective layer (a) by gravure coating;
Forming the surface protective layer (b) by embedding a surface protective agent coated on the surface of the surface protective layer (a) in a concave pattern of the transparent polypropylene resin layer by wiping coating;
In this order, a method for producing a decorative sheet.

Images