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JP-2026076049-A - Method for manufacturing surface protective film, hard coat film with surface protective film, and resin molded product

JP2026076049AJP 2026076049 AJP2026076049 AJP 2026076049AJP-2026076049-A

Abstract

[Problem] The present invention aims to provide a surface protective film for a hard coat layer that, even when a protective layer is applied to a semi-cured hard coat layer, does not cause streaks on the hard coat layer when the protective layer is peeled off, and also has good adhesion to the hard coat layer after it has hardened. [Solution] A surface protection film for protecting the hard coat layer of a film having a hard coat layer as its outermost layer, wherein the surface protection film has an adhesive layer formed on one outermost surface of a substrate, the substrate contains a thermoplastic resin, and the adhesive layer contains, with respect to the entire adhesive layer, elastomer in an amount greater than 70% by mass and 95% by mass or less, thermoplastic resin in an amount of 3 to 25% by mass, and tackifier in an amount of 2 to 25% by mass. [Selection Diagram] None

Inventors

  • 山口 和也

Assignees

  • 株式会社サンエー化研

Dates

Publication Date
20260511
Application Date
20241023

Claims (15)

  1. In a surface protective film for protecting the hard coat layer of a film having a hard coat layer as its outermost layer, The aforementioned surface protection film has an adhesive layer formed on one of its outermost surfaces, The aforementioned substrate contains a thermoplastic resin, The adhesive layer is a surface protective film containing, with respect to the entire adhesive layer, 65% to 95% by mass of elastomer, 3% to 25% by mass of thermoplastic resin, and 2% to 25% by mass of tackifier.
  2. The surface protective film according to claim 1, wherein the elastomer is a styrene-based elastomer.
  3. The surface protective film according to claim 1 or 2, wherein the thermoplastic resin is a polyolefin resin.
  4. The surface protective film according to claim 1 or 2, wherein the surface protective film is cut to a width of 25 mm x length of 200 mm, and a test piece obtained by laminating it to a hard coat layer using a 2 kg roller is left standing at 23°C for one day, and the adhesive strength of the surface protective film to the hard coat layer (peeling speed 0.3 m/min, 180° peel) is in the range of 0.01 N/25 mm or more and 0.5 N/25 mm or less.
  5. The surface protective film according to claim 1 or 2, wherein the surface protective film is cut to a width of 25 mm x length of 200 mm, and a test piece obtained by laminating it to a hard coat layer using a 2 kg roller is left standing at 23°C for one day, and the adhesive strength of the surface protective film to the hard coat layer (peeling speed 0.3 m/min, 180° peel) is in the range of 0.01 N/25 mm or more and 0.30 N/25 mm or less.
  6. The surface protective film according to claim 1 or 2, wherein the surface protective film is cut to a width of 25 mm x length of 200 mm, and a test piece obtained by laminating it to a hard coat layer using a 2 kg roller is left to stand at 100°C for 2 hours, and the adhesive strength of the surface protective film to the hard coat layer (peeling speed 0.3 m/min, 180° peel) is in the range of 0.01 N/25 mm or more and 0.5 N/25 mm or less.
  7. The surface protective film according to claim 1 or 2, wherein the surface roughness of the adhesive layer is in the range of 0.01 μm to 0.30 μm.
  8. The surface protective film according to claim 1 or 2, wherein the surface roughness of the adhesive layer is in the range of 0.01 μm or more and 0.10 μm or less.
  9. A hard-coat film with a surface protection film, comprising a hard-coat film having an adhesive layer of the surface protection film described in claim 1 or 2 and a hard-coat layer as the outermost layer, with the hard-coat layer of the hard-coat film laminated to it.
  10. The hard coat film with a surface protective film according to claim 9, wherein the hard coat film with a surface protective film is a hard coat film with a surface protective film for resin molding.
  11. The hard coat film with a surface protective film according to claim 10, wherein the resin molding is performed by in-mold molding or in-mold lamination molding.
  12. A method for manufacturing a resin molded body, comprising: applying a hard coat forming composition to one of the outermost layers of a film to form a hard coat layer; laminating the adhesive layer of the surface protection film described in claim 1 or 2 to the hard coat forming composition layer while the hard coat layer is semi-cured to form a hard coat film with a surface protection film; performing resin molding using the hard coat film with the surface protection film and a resin; and then curing the hard coat layer.
  13. A method for manufacturing a resin molded body, comprising applying a hard coat-forming composition to one of the outermost layers of a film to form a hard coat layer, curing the hard coat layer, then laminating the adhesive layer of the surface protection film described in claim 1 or 2 to the hard coat layer to form a hard coat film with a surface protection film, and finally performing resin molding using the hard coat film with the surface protection film and a resin.
  14. A method for manufacturing a resin molded article according to claim 12, wherein the resin molding is performed by in-mold molding or in-mold lamination molding.
  15. A method for manufacturing a resin molded article according to claim 13, wherein the resin molding is performed by in-mold molding or in-mold lamination molding.

Description

This invention relates to a surface protection film, a hard coat film with a surface protection film, and a method for manufacturing a resin molded article. Resin molded products are widely used in mobile information terminals such as mobile phones, notebook computers, home appliances, and automotive interior and exterior parts. These resin molded products are typically decorated after molding to enhance their aesthetic appeal. Known decorative methods include applying a decorative film, which has a design or hard coat layer created by printing or coating onto the film, to the surface of the resin molded product using methods such as in-mold molding and in-mold lamination molding. For example, a protective layer-added decorative film is known in which a protective film consisting of an adhesive layer made of an acrylic elastomer and at least one substrate layer is attached to a thermo-cured hard coat layer made of an acrylic acid copolymer and an isocyanate curing agent (see Patent Document 1). On the other hand, in-mold lamination molding (hereinafter sometimes abbreviated as "IML method" in this specification), one method of in-mold molding, is a technique in which a decorative film, in which a hard coat layer is formed on one side of a base film and a pattern layer, adhesive layer, etc., is formed on the other side, is held inside an injection molding die, and the decorative film is bonded to the surface of the resin molded product simultaneously with injection molding. A moldable laminated hard coat film used in the IML method is known, characterized by having a hard coat layer containing an active energy ray curable resin on a base film, the hard coat layer containing a hindered phenol-based antioxidant in an amount of 1 to 10 parts by weight per 100 parts by weight of the active energy ray curable resin, and the laminated hard coat film having an elongation rate of 30% or more at 23°C and 50% RH after heat treatment at 150°C or higher (see Patent Document 2). The moldable laminated hard coat film described in Patent Document 2 is manufactured by coating one side of a base film with a coating composition containing at least an active energy ray-curable resin, a polymerization initiator, and a hindered phenol-based antioxidant, drying it to form a hard coat layer, irradiating the hard coat layer with active energy rays as needed, and then laminating a protective film on the side of the hard coat layer opposite to the base film. In this case, the hard coat layer is not completely cured but is in a semi-cured state. Furthermore, the resin molded product using the moldable laminated hard coat film described in Patent Document 2 is manufactured by first forming a decorative layer on the moldable laminated hard coat film by printing or other means as needed, then preheating the moldable laminated hard coat film, and subsequently creating a resin molded body by simultaneously molding and integrating the moldable laminated hard coat film with the resin material using the IML method. Afterward, the moldable laminated hard coat film integrated with the resin molded body is subjected to post-exposure with active energy rays to achieve complete curing. Furthermore, as the protective film for the molded laminated hard coat film described in Patent Document 2, polyethylene terephthalate (PET) film, polyolefin-based film (e.g., polyethylene, polypropylene, etc.) can be preferably used, and as the material for the adhesive layer for providing the protective film on the hard coat layer, acrylic, urethane, polyester, rubber, and silicone-based adhesives can be used. Japanese Patent Publication No. 2018-171708Japanese Patent Publication No. 2012-210755 The present invention relates to a surface protection film for protecting the hard coat layer of a film having a hard coat layer as its outermost layer. The surface protection film comprises a substrate with an adhesive layer formed on one outermost surface. The substrate contains a thermoplastic resin, and the adhesive layer contains an elastomer, a thermoplastic resin, and a tackifier. The thermoplastic resin contained in the substrate constituting the surface protective film of the present invention is not particularly limited, and specifically includes polycarbonate resin, an alloy of polyphenylene ether resin and polystyrene resin, an alloy of polyphenylene ether resin and polyamide resin, thermoplastic polyester resin, methyl methacrylate/acrylonitrile/butadiene/styrene copolymer resin, methyl methacrylate/styrene copolymer resin, methyl methacrylate resin, rubber-reinforced methyl methacrylate resin, polyamide resin, polyacetal resin, polylactic acid resin, polyolefin resin, polyphenylene sulfide resin, and the like. Among the thermoplastic resins contained in the substrate constituting the surface protective film of the present invention, polyolefin resins or polyester resins are particularly preferred. Specific examples of the polyolefin resins include low-density