JP4710385B2 - Decorative sheet for metal decorative board - Google Patents

Description

  The present invention relates to a decorative sheet used for housing building materials, automobile interiors, and the like, and more particularly, to a decorative sheet suitable for bending by bonding to metal.

  As a method of imparting a design to a metal surface, there was a coated steel sheet that maintained its design by resin coating, but since high design properties and embossed expression cannot be obtained by painting, it is made of vinyl chloride. The decorative sheet has been specified as a decorative sheet for metal plates.

  However, demands for decorative sheets other than vinyl chloride have increased due to environmental problems caused by vinyl chloride in recent years, particularly concerns regarding the generation of chlorine and dioxins during combustion. Under such circumstances, a decorative sheet using an acrylic resin, a decorative sheet using a completely non-crystalline polyester resin, and the like have appeared. However, these vinyl chloride substitute decorative sheets use expensive resins as compared with vinyl chloride resins, and are not perfect substitutes.

  In addition, there is an example of using an inexpensive polyolefin-based resin decorative sheet, but there are problems such as whitening and cracking at the time of bending, and the usable parts are limited. Recently, there have been some products that use olefinic thermoplastic elastomers to which soft components such as reactor-type olefinic thermoplastic elastomers and rubber components are added, but these sheets have good bending workability but low surface hardness. There was also the fault of being easily scratched.

  The present invention solves the problems as described above, and the problem is that it is a decorative sheet using a non-chlorine resin other than the conventional vinyl chloride resin, and has an excellent bending process and a surface. The object is to provide a decorative sheet having high hardness.

The present invention determines this problem, that is, the invention according to claim 1 is a decorative sheet for a metal decorative board having a transparent or translucent surface resin layer made of a polypropylene resin, wherein the surface resin layer comprises: It consists of a mixture obtained by adding 20 parts by weight of a styrene butadiene rubber having a styrene content of 15 % by weight to a random polypropylene having an ethylene concentration of 5% or less and an isotactic polypropylene having an isotactic index of 96. A decorative sheet for a metal decorative board.

  The present invention has a good resistance to whitening and cracking, and the metal decorative board to which the decorative sheet is bonded exhibits good folding processability and can be made into a decorative sheet having high folding processability. it can.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a cross-sectional structure of one embodiment of the decorative sheet of the present invention. A pattern layer 2 is applied to the base material sheet 1, and a surface resin layer 4 is laminated thereon via an adhesive layer 3. This is used by appropriately bonding to the metal plate 5.
As the substrate sheet 1, the pattern layer 2, the adhesive layer 3, and the metal plate 5 in the present invention, conventionally known materials can be used as appropriate. The adhesive layer is particularly preferably a two-component curable urethane type, but is not particularly limited thereto.

  The resin used in the surface resin layer 4 of the present invention is a random polypropylene having an ethylene concentration of 5% or less and an isotactic polypropylene having an isotactic index of 96 or more and a styrene content of 5 to 60% by weight. A mixture obtained by adding 5 to 40 parts by weight of a certain styrene butadiene rubber is used. The isotactic index here is the ratio of insoluble components after extraction with boiling heptane.

  When the styrene content of the styrene butadiene rubber is less than 5 or exceeds 60 parts by weight, craze generation is likely to occur at the styrene butadiene rubber interface in polypropylene, which may cause bending whitening.

  If the blend of styrene butadiene rubber is 5% by weight or less, the flexibility of the surface resin layer is not sufficient and cracking and whitening easily occur when bent, and if the blending ratio exceeds 40% by weight, the flexibility is improved. The problem that surface hardness becomes low and is easy to be damaged appears.

  Also, since styrene butadiene rubber has a double bond in the butadiene block and may turn yellow due to ultraviolet rays, the use of hydrogenated styrene butadiene rubber with hydrogen to saturate the double bond can improve weather resistance. I can do it.

  As styrene butadiene, styrene-butadiene-styrene (SBS), styrene-isoprene-styrene (SIS), styrene-ethylene / butylene-styrene (SEBS), styrene-ethylene / propylene-styrene (SEPS), styrene-butadiene. (SB), styrene-ethylene / propylene (SEP), styrene-ethylene / butylene (SEB) and hydrogenated styrene-butadiene (HSB), styrene-ethylene-butadiene / olefin crystals (SEBC), olefin crystals / ethylene-butadiene / Examples thereof include olefin crystals (CEBC).

  Further, if the MFR of the styrene butadiene rubber is 2 g / 10 min or less, the resin pressure in the extrusion process is high and the productivity is low. In the case of 20 g / 10 min or more, selection of a polypropylene resin is often restricted in order to obtain an optimal fine dispersion form.

  Further, an antioxidant may be added as appropriate when the surface resin layer 4 is extruded as a film, and an antioxidant is added to prevent thermal oxidation of the resulting product, and a light stabilizer is added to prevent deterioration due to ultraviolet rays. The type and amount of these additives are not particularly limited, but a combination of those commonly used for olefin resins is sufficient.

  In addition, as a method of laminating the surface resin layer 4 on the base sheet 1, there are a heat laminating method, a dry laminating method, an extrusion laminating method, a knee laminating method, etc. It ’s fine.

  Adhesion between the decorative sheet and the metal plate 5 is based on an adhesive, but is not particularly defined, and a general object is sufficient, and a primer layer may be provided on the back surface of the decorative sheet.

  A polyethylene resin film was used as the base sheet 1, and a wood grain pattern was printed thereon by gravure printing using urethane-based ink to form a picture layer 2.

  On the pattern layer 2 obtained above, a urethane-based adhesive 3 was applied to a thickness of about 5 μm by a gravure printing method. Thereafter, 0.2% by weight of a phenolic antioxidant, 0.3% by weight of a hindered amine light stabilizer, and 0.5% by weight of a benzotriazole ultraviolet absorber are added, and a random polypropylene having an ethylene concentration of 5% or less. A surface resin layer 4 is formed by melt extrusion using a mixed resin to which 20 parts by weight of isotactic polypropylene having an isotactic index of 96 and styrene content rubber having a styrene content of 15% by weight is added, and the adhesive 3 is provided. The laminated surface was dry laminated using a two-component curable urethane adhesive to obtain a decorative sheet.

  Thereafter, a urethane-modified polyester polyol / polyisocyanate adhesive was applied to the hot-dip galvanized steel plate 5 by roll coating so that the coating thickness after drying was 5 g / m 2, and the steel plate was applied at 200 ° C. for 3 minutes. This was heated and bonded to the base sheet 1 side of the decorative sheet and bonded with a rubber roll, and then rapidly cooled in a water tank to obtain a metal decorative board.

<Comparative Example 1>
In Example 1, a decorative sheet was obtained in the same manner as in Example 1 except that the ethylene content of random polypropylene was changed to 30% to obtain a metal decorative board.

  Two types of bending processing were performed on the metal decorative plates obtained in Example 1 and Comparative Example 1 above, and the presence or absence of whitening of the processed portion was visually evaluated. Furthermore, the surface hardness was evaluated by the pencil hardness test of JISK5600. Finally, ultraviolet rays were irradiated with a sunshine weatherometer, and the appearance change after 1000 hours was visually evaluated. The results are shown in Table 1.

  Needless to say, the decorative sheet and the metal decorative board obtained in Example 1 are non-vinyl chloride resins, and as is apparent from Table 1, the decorative metal sheet and the metal decorative board were excellent in bending workability and pencil hardness. .

  The decorative sheet 1 and the metal decorative board obtained in Comparative Example 1 had good bending whitening properties but poor scratch resistance.

It is explanatory drawing which showed the structure of the cross section of one Example of the decorative sheet of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Base material sheet 2 ... Picture layer 3 ... Adhesive layer 4 ... Surface resin layer 5 ... Metal plate

Claims (1)

In a decorative sheet for a metal decorative board having a transparent or translucent surface resin layer made of a polypropylene resin, the surface resin layer has a random polypropylene having an ethylene concentration of 5% or less, and an isotactic index of 96 . A decorative sheet for a metal decorative board, comprising a mixture obtained by adding 20 parts by weight of styrene butadiene rubber having a styrene content of 15 % by weight to polypropylene.

Images