JP2009292079A - Decorative sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an easily available decorative sheet which includes excellent flexibility compared with conventional decorative sheets using a polypropylene resin, causes less whitening or cracking during bending processing and is excellent in designability. <P>SOLUTION: The decorative sheet is constituted by laminating at least one transparent polyolefinic resin layer (2), based on a polypropylene resin overlying a substrate sheet (6) made of a non-polyvinyl chloride type material through an adhesive layer (34). The transparent polyolefinic resin layer (2) includes a tensile elastic modulus of 100-500 MPa and a tensile breaking elongation of ≥500%, based on JIS K7161. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a decorative sheet suitably used for building exteriors and interiors, for building surfaces, frame materials, surface materials for household electrical appliances, and building materials such as flooring. The present invention also relates to a decorative board formed by bonding the decorative sheet to the surface of a metal plate.

  Conventionally, for surface decoration of building entrance doors and steel sheet material exterior members, a decorative sheet directly applied with a decorative pattern on a steel sheet member, or a decorative sheet provided with printing and uneven embossing on a polyvinyl chloride sheet Has been used to bond steel sheet members with adhesives, etc., but it is difficult to express a design with unevenness by applying decorative patterns by painting, and decorative patterns using polyvinyl chloride decorative sheets Grants also tend to be shunned in recent years due to growing environmental awareness.

  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 characteristics as polyvinyl chloride decorative sheets and have a low environmental impact have attracted attention. In particular, decorative sheets mainly made of polypropylene resin tend to be less expensive to manufacture, including raw material costs, compared to the case of using acrylic resin, and there is a high market demand for polyolefin-based decorative sheets. .

  However, since the bending process of the metal decorative plate obtained by bonding such a polyolefin-based decorative sheet to the metal plate is usually performed by press molding, the V-groove is used like a decorative plate using a wooden or inorganic plate. Compared with the case where the bending process is performed after the processing, the load applied to the folding part of the decorative sheet during the bending process is large, and the decorative sheet is locally stretched greatly at the folding part. The load applied during folding is greater for the surface layer of the decorative sheet. In particular, when a highly elastic polypropylene resin is used for the transparent olefin resin layer, whitening or cracking is likely to occur in the polypropylene resin layer due to the load applied during folding. It was.

In order to cope with such a situation, there are many non-polyvinyl chloride or polyolefin type decorative sheets and metal decorative plates using the same that prevent whitening and cracking even in post-processing after the decorative sheets are bonded. It has been developed and proposed (see, for example, Patent Document 1). However, the quality required for post-folding suitability after bonding on a decorative sheet or a metal decorative board is strict, and development of a higher-quality decorative sheet and a metal decorative board using the same is desired.
JP 2001-162744 A

The present invention has been made in view of such circumstances, and is a makeup in which at least one transparent polyolefin resin layer composed mainly of a polypropylene resin is laminated on a base sheet made of a non-polyvinyl chloride material. An object of the present invention is to easily provide a decorative sheet that is a sheet and has a softness superior to a decorative sheet using a conventional polypropylene resin, is less likely to be whitened or cracked during bending, and has an excellent design. To do.
Another object of the present invention is to provide a decorative board obtained by bonding the decorative sheet to a metal plate.

  According to the first aspect of the present invention, at least one transparent polyolefin resin layer composed of a polypropylene resin as a main resin is laminated on a base sheet made of a non-polyvinyl chloride material via an adhesive layer. The decorative polyolefin sheet is a decorative sheet characterized in that the transparent polyolefin resin layer has a tensile elastic modulus of 100 MPa or more and 500 MPa or less and a tensile elongation at breakage of 500% or more according to JIS K7161. In the present invention, “transparent” includes translucent.

  The invention according to claim 2 is the decorative sheet according to claim 1, wherein the polypropylene resin is homopolypropylene and an isotactic pentad fraction is 55 to 75%.

  The invention described in claim 3 is a decorative board obtained by bonding the decorative sheet according to claim 1 or 2 on a metal plate.

  According to the present invention, it is possible to provide a decorative sheet and a decorative plate that have superior flexibility than a decorative sheet using a conventional polypropylene resin, are less prone to whitening and cracking during bending, and have excellent design properties. it can.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing a cross-sectional structure of one embodiment of the decorative sheet of the present invention. On the base sheet (6), a pattern ink layer (5), an adhesive layer (34), a transparent polyolefin resin layer (2), and a surface protective layer (1) are laminated in this order. As shown in FIG. 1, the adhesive layer (34) may have a two-layer structure of an adhesive resin layer (3) and an adhesive layer (4). Moreover, in order to improve the designability, you may provide an embossed pattern suitably in the surface protective layer (1) side.

  When the decorative sheet shown in FIG. 1 is used as a surface decoration such as a steel plate member to be bonded, the base sheet (6) is colored to block the influence of the surface state of the member to be decorated, and further imparts design properties. Therefore, it is common that a pattern ink layer (5) such as a wood grain pattern, a stone pattern, or an abstract pattern is provided.

It is important that the transparent polyolefin resin layer used for the decorative sheet of the present invention has a tensile elastic modulus according to JIS K7161 of 100 MPa or more and 500 MPa or less and a tensile breaking elongation of 500% or more. In decorative sheets using a transparent polyolefin resin layer with a tensile modulus exceeding 500 MPa, crystallization proceeds by heating and cooling with thermal lamination with a metal plate such as a steel plate, the sheet becomes hard and whitening and cracking occurs during bending processing. To do. In the bending process, it is preferable that the tensile elastic modulus of the transparent polyolefin resin layer to which a load is applied is 500 MPa or less. It tends to occur and lacks processing stability and workability.
In order to achieve the tensile modulus and tensile elongation at break, there are methods such as reducing the crystallinity.
The tensile elastic modulus is preferably 100 MPa or more and 300 MPa or less, and the tensile breaking elongation is preferably 600% or more and 700% or less.

  Furthermore, it is preferable that the polypropylene resin used for the decorative sheet of the present invention is homopolypropylene and has an isotactic pentad fraction of 55 to 75%. When the degree of crystallization exceeds this range, crystallization proceeds due to a thermal history in decorative sheet lamination and bonding to a metal plate, and whitening and cracking are likely to occur during bending. Moreover, when less than this range, the surface hardness as a decorative sheet will also fall.

  Further, in the transparent polyolefin resin layer used for the decorative sheet of the present invention, various materials such as various polyethylenes, α-olefins, ethylene-propylene rubbers, styrene-butadiene rubbers are used to improve the performance or moldability as decorative sheets. Is also possible. However, if a material that is not compatible with polypropylene is blended, a sea-island structure is formed, which causes bending whitening. The blending ratio of such other materials is preferably 40% by weight or less in the transparent polyolefin resin layer.

  The transparent polyolefin resin layer used here has a heat stabilizer, a flame retardant, an ultraviolet absorber, a light stabilizer, an anti-blocking agent, a nucleating agent, a catalyst scavenger, and a transparency maintaining range as necessary. A colorant, a light scattering agent for making translucent, a gloss adjusting agent, and the like can also be added. Hindered phenols, sulfurs, hydrazines, etc. as heat stabilizers, aluminum hydroxide, magnesium hydroxide, etc. as flame retardants, benzotriazoles, benzoates, benzophenones, triazines, etc. as UV absorbers, light As a stabilizer, a hindered amine or the like is generally added in any combination. In particular, when used in this application, it is necessary to consider weather resistance, and it is preferable to use an ultraviolet absorber and a light stabilizer, and the addition amount is 0.1 to 1.0% by weight in the transparent polyolefin resin layer, respectively. It is.

  As a method of laminating the transparent polyolefin resin layer (2) on the base sheet (6), lamination by dry lamination or lamination by extrusion lamination is possible. In the case of dry laminating, it is necessary to form a sheet of a transparent polypropylene-based resin layer in advance before bonding, whereas in the case of extrusion laminating, bonding is performed while forming a transparent polyolefin resin layer. It is possible and preferred.

  Moreover, according to the bonding method, you may use the thermoplastic resin layer which has adhesiveness in the bonding interface of a base material sheet and a transparent polyolefin resin layer, an adhesive layer, etc.

  Since the transparent polyolefin resin layer (2) is relatively soft, it is preferable to provide the surface protective layer (1) in consideration of scratch resistance, chemical resistance, and weather resistance. The material used for the surface protective layer is not particularly specified, but polyurethane, acrylic, acrylic silicon, fluorine, epoxy, vinyl, polyester, melamine, aminoalkyd, urea, etc. Can be selected as appropriate. In order to further improve the hardness of the coating film surface, it is possible to use a resin that is cured by irradiation with ultraviolet rays or electron beams. In order to provide weather resistance to the surface protective layer itself, it is desirable to provide an ultraviolet absorber and a light stabilizer.

  Further, in order to impart various functions to the transparent polyolefin resin layer (2) or the surface protective layer (1), functional additives such as antibacterial materials and fungicides can be optionally added. Furthermore, addition of alumina, silica, silicon nitride, silicon carbide, glass beads, etc. can be arbitrarily performed for adjusting the gloss from the design of the surface or for imparting further wear resistance. The appropriate coating thickness is usually 2 μm to 10 μm.

  The base sheet (6) is a paper such as thin paper, titanium paper, resin-impregnated paper, polyethylene, polypropylene, polybutylene, polystyrene, polycarbonate, polyester, polyamide, ethylene-vinyl acetate copolymer, polyvinyl alcohol, acrylic and other synthetic resins, Or foams of these synthetic resins, ethylene-propylene copolymer rubber, ethylene-propylene-diene copolymer rubber, styrene-butadiene copolymer rubber, styrene-isoprene-styrene block copolymer rubber, rubber such as polyurethane, organic or inorganic Non-woven fabric, synthetic paper, aluminum, iron, gold, silver and other metal foils can be arbitrarily selected. Moreover, although the colored base material colored with various pigments is generally used for the base material sheet (6), it is also possible to use transparent and translucent base material sheets.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further, this invention is not restrict | limited to the following example.

(Example 1)
Homopolypropylene resin with an isotactic pentad fraction of 75% is melt-extruded with an extruder at a thickness of 90 μm, and a polypropylene-based substrate sheet (thickness 70 μm) with a pattern ink layer and a two-component curing type urethane system Bonding was performed by dry lamination via an adhesive (AD806; manufactured by Toyo Morton Co., Ltd.). A two-component curable urethane surface protective agent was applied to the surface of the homopropylene resin layer on the base sheet in a thickness of 6 μm to obtain a decorative sheet of the present invention. The tensile modulus of the homopropylene resin layer on the substrate sheet was 400 MPa, and the tensile elongation at break was 550%.

(Example 2)
80 parts by weight of homopolypropylene resin with an isotactic pentad fraction of 75% is melt-blended with 20 parts by weight of low-density polyethylene to a thickness of 80 μm, and is combined with an adhesive olefin resin (thickness 10 μm) with an extruder. Extrusion was performed, and a polypropylene base sheet (thickness: 70 μm) having a pattern ink layer was bonded thereto. A two-component curable urethane surface protective agent was applied to the surface of the transparent polyolefin resin layer on the base sheet in a thickness of 6 μm to obtain a decorative sheet of the present invention. The tensile modulus of the transparent polyolefin resin layer was 200 MPa, and the tensile elongation at break was 600%.

(Comparative Example 1)
A polypropylene base material sheet is formed by melt blending 20 parts by weight of low density polyethylene into 80 parts by weight of homopolypropylene resin having a 90% isotactic pentad fraction and melt-extrusion with an extruder. (Thickness 70 μm) and a two-component curing type urethane adhesive (AD806; manufactured by Toyo Morton Co., Ltd.) were used for bonding by dry lamination. A two-component curable urethane-based surface protective agent was applied to the surface of the polypropylene resin layer on the base sheet in a thickness of 6 μm to obtain a decorative sheet. The tensile elastic modulus of the polypropylene resin layer on the substrate sheet was 1500 MPa, and the tensile elongation at break was 500% or more.

(Comparative Example 2)
Homopolypropylene resin (thickness 80 μm) with an isotactic pentad fraction of 50% is co-extruded with an adhesive olefin resin (thickness 10 μm) with an extruder, and a polypropylene base having a pattern ink layer The material sheet was bonded to 70 μm. A two-component curable urethane surface protective agent was applied to the surface of the homopolypropylene resin with a thickness of 6 μm to obtain a decorative sheet. The homopolypropylene resin layer on the base sheet had a tensile modulus of 80 MPa and a tensile elongation at break of 500% or more.

  The decorative sheets of Examples 1 and 2 and Comparative Examples 1 and 2 were bonded to a steel plate metal plate using a commercially available olefin / steel plate adhesive.

  The obtained metal plates were left in a thermostatic bath at 25 ° C. for 6 hours, and then bent by 90 degrees, and the whitening state of the bent portion was evaluated. Moreover, the surface hardness was evaluated with a pencil in accordance with JIS K5060 5-4 on a smooth surface, and the results are shown in Table 1.

[Table 1]

  In Example 1 and Example 2 according to the present invention, whitening and cracking due to bending are not observed. In Comparative Example 1, which has a high crystallinity with an isotactic pentad fraction, the surface hardness is stronger than that of the Example, but whitening and cracking are generated by bending. In Comparative Example 2 in which the degree of crystallinity is lowered, there is no cracking due to bending, but whitening and a decrease in surface hardness are observed.

  From the above results, according to the present invention, it is possible to provide a decorative sheet having moderate scratch resistance and excellent bending workability.

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

Explanation of symbols

(1) ... Surface protective layer (2) ... Transparent polyolefin resin layer (34) ... Adhesive layer (3) ... Adhesive resin layer (4) ... Adhesive layer (5) ... Pattern ink layer (6) ... Base Material sheet

Claims (3)

  In a decorative sheet comprising a base sheet made of a non-polyvinyl chloride material and a transparent polyolefin resin layer composed of polypropylene resin as a main resin, laminated through an adhesive layer, the transparent polyolefin A decorative sheet, wherein the resin layer has a tensile modulus of 100 MPa or more and 500 MPa or less and a tensile elongation at breakage of 500% or more in accordance with JIS K7161.   The decorative sheet according to claim 1, wherein the polypropylene resin is homopolypropylene and has an isotactic pentad fraction of 55 to 75%.   A decorative sheet obtained by bonding the decorative sheet according to claim 1 or 2 on a metal plate.

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