JP2007125836A - Polylactic acid resin laminated body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated body of a polylactic acid resin having a transparency and a heat resistance and not generating whitening on a jointed part or the like even if a solvent type adhesive is used. <P>SOLUTION: The laminated body comprises a surface layer made from a polymethyl methacrylate resin on at least one side of a substrate layer comprising a resin composition comprising the polylactic acid resin blended with the polymethyl methacrylate resin. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a polylactic acid resin laminate having transparency, heat resistance and improved solvent adhesion.

  Polylactic acid resin is obtained from plants such as corn, and unlike conventional petroleum resins such as polystyrene, polypropylene, polyvinyl chloride, and polyethylene, it has effects such as prevention of petroleum resource depletion and suppression of carbon dioxide emissions. It is expected to be a material that can replace petroleum-based resins, and is used for agricultural and food packaging films. In addition, this polylactic acid resin has excellent transparency, and is demanded to be used for applications such as display fixtures such as display cases.

  However, since polylactic acid resin is inferior in heat resistance, there exists a problem that a use environment etc. are restrict | limited. Therefore, a thermoplastic resin composition composed of a polylactic acid polymer and an acrylic polymer has been proposed for the purpose of improving heat resistance while making use of the transparency of the polylactic acid resin (Patent Document 1).

As described above, the molded body composed of the composition of the polylactic acid resin and the acrylic polymer is improved in heat resistance as much as possible. The phenomenon of whitening by the adhesive is observed. That is, in general, a display case or the like is assembled and manufactured by using a plurality of sheet-like molded bodies with an adhesive (solvent type). At this time, whitening occurs due to the occurrence of cracks or the like in the adhesive surface and the portion where the solvent sticks out of the adhesive surface. As a result, there is a problem that the appearance of the product is remarkably deteriorated and lacks in design properties.
JP 2004-269720 A

  An object of the present invention is to provide a polylactic acid resin laminate that solves the above-described problems, has transparency and heat resistance, and does not cause whitening on a joint surface or the like even when joined using a solvent-type adhesive. And

  The present invention relates to a polylactic acid resin comprising a base layer made of a resin composition in which a polymethyl methacrylate resin is blended with a polylactic acid resin, and a surface layer made of a polymethyl methacrylate resin laminated on at least one surface of the base layer. The summary is a laminate.

  The polylactic acid resin laminate of the present invention is obtained by laminating a surface layer made of a polymethyl methacrylate resin on a base layer made of a resin composition in which a polymethyl methacrylate resin is blended with a polylactic acid resin. When the adhesive process using a solvent-type adhesive with heat resistance is maintained, the adhesive surface and the part where the solvent adheres due to the solvent are whitened. Without causing it, it can be suitably used for applications such as furniture such as display cases.

  The polylactic acid resin used for the base material layer of the present invention is obtained by condensation-dehydrating L-lactic acid, D-lactic acid, LD-lactic acid or a mixture thereof, or by ring-opening polymerization of lactide of lactic acid. The content ratio of L-polylactic acid and D-polylactic acid is not limited.

  As the polymethyl methacrylate resin used for the base material layer and the surface layer, a resin comprising methyl methacrylate alone or a copolymer of 50% by weight or more of methyl methacrylate and another copolymerizable ethylenically unsaturated monomer is used. .

  The blending ratio of the polylactic acid resin and the polymethyl methacrylate resin of the base material layer is preferably blended so as to be 80/20 to 5/95. If the ratio of the polymethyl methacrylate resin is less than 20, sufficient heat resistance cannot be obtained. On the other hand, if it exceeds 95, it is not suitable from the viewpoint of effects such as prevention of depletion of petroleum resources and suppression of carbon dioxide emission.

  The thickness of the surface layer is preferably in the range of 30 to 500 μm, and may be laminated on either one side or both sides of the base material layer. Examples of the lamination method include well-known methods such as co-extrusion, thermal lamination, and lamination by press molding.

  Polylactic acid resin (poly L-lactic acid resin having a weight average molecular weight of 200,000 and a D-form content of 2%, trade name “Lacia H400”, manufactured by Mitsui Chemicals) and polymethyl methacrylate resin (polymethacrylic acid) Methyl resin, trade name “SUMIPEX EX” (manufactured by Sumitomo Chemical Co., Ltd.) were mixed, and a sheet-like molded body having a thickness of 3 mm was obtained by extrusion molding. On the other hand, a polymethyl methacrylate resin film (acrylic graft copolymer-containing methacrylic polymer, trade name “Sanduren 014”, manufactured by Kaneka Corporation) having a thickness of 50 μm was prepared, and the sheet obtained as described above. A polymethyl methacrylate resin film was laminated on the surface of the molded body by a heat laminating method.

  The obtained laminate was checked for cross-sectional adhesion using a 20 mm × 20 mm sample as a sample. When an adhesive solvent (dichloromethane) was injected from a portion where the surfaces on which the acrylic films of the samples were laminated were in contact with each other with a syringe, no whitening phenomenon was observed.

Claims (1)

  A polylactic acid resin laminate comprising a base material layer comprising a resin composition in which a polymethyl methacrylate resin is blended with a polylactic acid resin, and a surface layer comprising a polymethyl methacrylate resin laminated on at least one surface of the base material layer.