JP2005212242A - Polylactic acid type film and decorative sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an easily adhesive polylactic acid type film having both of high transparency and printability in order to obtain a decorative sheet having excellent design properties, and the decorative sheet. <P>SOLUTION: The polylactic acid type film having at least 90% light permeability is obtained by laminating a layer (layer B) containing at least one resin selected from an acrylic resin, a polyester resin and a urethane resin at least on one side of a layer (layer A) comprising a polylactic acid type resin. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a polylactic acid film having good adhesion to printing inks and various coatings. In particular, since the polylactic acid-based film of the present invention is excellent in printability, it can be used as a decorative sheet or decorative sheet for decorating the surface of a substrate composed of a wooden substrate, a resin molded product, a resin sheet, a metal steel plate, etc. after printing. Suitable for use. The decorative sheet of the present invention can be suitably used for applications requiring high design properties such as building materials, electrical products, automobile parts, cards, and gaming machines.

  Conventionally, various resins are applied to a polyester film to develop easy adhesion.

  For example, Patent Document 1 shows an example in which an acrylic resin, a polyester resin, and a urethane resin are applied to a polyethylene terephthalate film and laminated.

  Patent Document 2 shows an example in which an antistatic agent and an antifogging agent are applied to a polylactic acid film, and Patent Document 3 has an easy-adhesion layer to which 10 to 50% by weight of a filler (silica-based inorganic particles) is added. Examples of laminated polylactic acid stretched sheets can be seen.

Furthermore, Patent Documents 4 and 5 show examples of using a polylactic acid film, which has started to spread as a non-petroleum polymer, as a decorative sheet due to the recent increase in environmental awareness.
JP 2002-79635 A (Examples 1 to 12) JP-A-10-86307 (Examples 1-1 to 1-8, 2-1 to 2-8) JP-A-10-120811 (Examples 1 and 2) Japanese Patent Laid-Open No. 11-129426 (Example 1) JP-A-11-227147 (Example)

  Although the use of polylactic acid-based films for decorative sheets, such as Patent Documents 4 and 5, has been observed due to increased environmental awareness, these films have improved printability (especially, adhesion to ink). It was desired.

  On the other hand, Patent Documents 1, 2, and 3 are examples of easy-adhesion coats, but the high transparency necessary for the polylactic acid-based decorative sheet intended in the present invention is not particularly considered and is insufficient.

  That is, the subject in this invention is obtaining the easily-adhesive polylactic acid-type film which has high transparency and printability, in order to obtain the decorative sheet which has the outstanding design property.

  In order to solve the above problems, the present invention has the following configuration. That is, the polylactic acid film of the present invention has at least one resin selected from the group consisting of an acrylic resin, a polyester resin and a urethane resin on at least one side of a layer (A layer) made of a polylactic acid resin as a main component. And a light transmittance is 90% or more.

  The polylactic acid-based film of the present invention has both high transparency and printability, and can be suitably used as a decorative sheet or a decorative sheet used by printing. The decorative sheet of the present invention can be suitably used for applications requiring high design properties such as building materials, electrical products, automobile parts, cards, and gaming machines.

  The polylactic acid film of the present invention has at least one resin selected from the group consisting of an acrylic resin, a polyester resin and a urethane resin as a main constituent component on at least one side of a layer (A layer) made of a polylactic acid resin. A layer (B layer) is laminated.

  Examples of the polylactic acid resin used in the A layer include polymers made of polylactic acid, lactic acid such as L-lactic acid and D-lactic acid, and copolymers with other hydroxycarboxylic acids. Other hydroxycarboxylic acids typically include glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 3-hydroxyvaleric acid, 4-hydroxyvaleric acid, 6-bidoxycaproic acid and the like. The polylactic acid resin may be used alone, but may be a mixture of two or more.

  From the standpoint of high heat resistance and transparency, and also from the viewpoint of hygiene such as antibacterial and antifungal properties, the polylactic acid film of the present invention is lactic acid or L-lactic acid relative to the entire polylactic acid resin. The ratio of the polymer composed of lactic acid such as D-lactic acid is preferably 90 mol% or more. Particularly, from the viewpoint of having long-term stability of physical properties and good anti-blocking properties, L-lactic acid is particularly preferable. Is preferably 95 mol% or more.

  Moreover, in this invention, it is preferable that melting | fusing point of a polylactic acid-type film is 150 degreeC or more. In particular, the melting point of the polylactic acid film is more preferably 155 ° C. or more, and particularly preferably 160 ° C. or more, from the viewpoints of heat resistance during molding and heat resistance during printing. This is because if the melting point is low, the heat resistance is poor and problems such as wrinkles occur during the drying process of printing, and wrinkles occur at the weld during injection molding. The melting point has no particular upper limit, but it is preferably 200 ° C. or less from the viewpoint of securing good heat formability in consideration of embossing, curved surface forming, bending, and the like.

  Here, the melting point in the present invention is a crystal melting peak caused by the polymer, and the minimum point of the melting endothermic peak obtained from the DSC curve when the temperature of the polymer (5 mg) is measured in a DSC under a nitrogen atmosphere, that is, This is the point at which the differential value becomes zero. In particular, when a polymer has a plurality of melting endothermic peaks, the main melting peak having the largest heat of fusion is defined as the melting point of the polymer.

  Moreover, it is preferable that the carboxyl terminal group density | concentration of the polylactic acid-type resin used by this invention is 40 equivalent / tons or less. More preferably, it is 30 equivalent / ton or less, Most preferably, it is 20 equivalent / ton or less. Exceeding this is not preferable because it causes deterioration of transparency. The method for setting the carboxyl end group concentration to 30 equivalents / ton or less is not particularly limited, but may be a method in which the polylactic acid resin is sufficiently dried before melt extrusion molding, or by solid-phase polymerization of the polylactic acid resin. And a method using a carboxyl terminal blocking agent. These techniques are also listed in, for example, Japanese Patent Application Laid-Open Nos. 2003-25427 and 2001-335626.

  Regarding the acrylic resin used for the B layer, examples of the monomer component constituting the acrylic resin include alkyl acrylate and alkyl methacrylate (the alkyl group is a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group). , Isobutyl group, t-butyl group, 2-ethylhexyl group, lauryl group, stearyl group, cyclohexyl group, phenyl group, benzyl group, phenylethyl group), 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxy Hydroxy group-containing monomers such as propyl acrylate and 2-hydroxypropyl methacrylate, acrylamide, methacrylamide, N-methyl acrylamide, N-methyl methacrylamide, N-methylol acrylamide, N-methylol Amide group-containing monomers such as tacrylamide, N, N-dimethylolacrylamide, N-methoxymethylacrylamide, N-methoxymethylmethacrylamide, N-phenylacrylamide, N, N-diethylaminoethyl acrylate, N, N-diethylaminoethyl methacrylate, etc. Amino group-containing monomers, glycidyl acrylate, epoxy group-containing monomers such as glycidyl methacrylate, monomers such as acrylic acid, methacrylic acid and salts thereof (lithium salt, sodium salt, potassium salt, etc.) or monomers containing such salts These may be copolymerized using one or more of them. Furthermore, these can be used in combination with other types of monomers.

  Examples of other types of monomers include epoxy group-containing monomers such as allyl glycidyl ether, sulfonic acids such as styrene sulfonic acid, vinyl sulfonic acid and salts thereof (lithium salt, sodium salt, potassium salt, ammonium salt, etc.). Monomers containing a carboxylic group such as crotonic acid, itaconic acid, maleic acid, fumaric acid and salts thereof (lithium salt, sodium salt, potassium salt, ammonium salt, etc.) or a salt thereof, Monomers containing acid anhydrides such as maleic anhydride and itaconic anhydride, vinyl isocyanate, allyl isocyanate, styrene, vinyl methyl ether, vinyl ethyl ether, vinyl trisalkoxysilane, alkyl maleic acid monoester, alkyl fumar Acid monoester, acrylonitrile, methacrylonitrile, alkyl itaconic acid monoester, vinylidene chloride, vinyl acetate, etc. can be used vinyl chloride.

  Moreover, a modified acrylic copolymer etc. can also be used as an acrylic resin of this invention, For example, the block copolymer modified | denatured with polyester, urethane, an epoxy, etc., a graft copolymer, etc. are mentioned.

  The glass transition point (Tg) of the acrylic resin used in the present invention is not particularly limited, but is preferably −10 to 90 ° C., more preferably 0 to 50 ° C., and most preferably 10 to 40 ° C. When an acrylic resin having a low Tg is used, the heat-resistant adhesiveness tends to be inferior or tends to be blocked. On the other hand, when it is too high, the adhesiveness may be deteriorated, the film forming property may be inferior, and the transparency may be lowered. It is not preferable. The molecular weight of the acrylic resin is preferably 50,000 or more, more preferably 300,000 or more from the viewpoint of adhesiveness.

  Preferable acrylic resins used in the present invention include copolymers selected from methyl methacrylate, ethyl acrylate, n-butyl acrylate, 2-hydroxyethyl acrylate, acrylamide, N-methylol acrylamide, and acrylic acid.

  In the present invention, the acrylic resin is preferably dissolved, emulsified or suspended in water and used as a water-based acrylic resin liquid from the viewpoint of environmental pollution and explosion-proof properties during application. Such water-based acrylic resins are copolymerized with monomers having a hydrophilic group (such as acrylic acid, methacrylic acid, acrylamide, vinyl sulfonic acid and salts thereof), emulsion polymerization using reactive emulsifiers and surfactants, and suspension polymerization. It can be prepared by a method such as turbid polymerization or soap-free polymerization.

  The polyester resin used in the B layer has an ester bond in the main chain or side chain, and is preferably obtained by polycondensation of dicarboxylic acid and diol.

  As the carboxylic acid component constituting the polyester resin, aromatic, aliphatic, and alicyclic dicarboxylic acids and trivalent or higher polyvalent carboxylic acids can be used.

  As aromatic dicarboxylic acids, terephthalic acid, isophthalic acid, orthophthalic acid, phthalic acid, 2,5-dimethylterephthalic acid, 1,4-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,2 -Bisphenoxyethane-p, p'-dicarboxylic acid, phenylindanedicarboxylic acid, etc. can be used. From the viewpoint of the strength and heat resistance of the laminated film, these aromatic dicarboxylic acids are preferably polyesters that occupy 30 mol% or more, more preferably 35 mol% or more, and most preferably 40 mol% or more of the total dicarboxylic acid component. It is preferable to use it.

  Examples of the aliphatic and alicyclic dicarboxylic acids include succinic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, dimer acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid and the like, and ester-forming derivatives thereof can be used.

  Examples of the glycol component of the polyester resin include ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, and 1,5-pentanediol. 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 2,4-dimethyl-2-ethylhexane-1,3 -Diol, neopentyl glycol, 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2, 2,4-trimethyl-1,6-hexanediol, 1,2- Chlohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, 4,4'-thiodiphenol, bisphenol A 4,4′-methylenediphenol, 4,4 ′-(2-norbornylidene) diphenol, 4,4′-dihydroxybiphenol, o-, m-, and p-dihydroxybenzene, 4,4′-isopropylidene Phenol, 4,4′-isopropylidene bin diol, cyclopentane-1,2-diol, cyclohexane-1,2-diol, cyclohexane-1,4-diol and the like can be used.

  Moreover, it is possible to use polyhydroxycarboxylic acid as a polyester resin used for B layer. Typical examples of the monomer unit of polyhydroxycarboxylic acid include lactic acid, glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 3-hydroxyvaleric acid, 4-hydroxyvaleric acid, 6-bidoxycaproic acid and the like. Can be mentioned. The polyhydroxycarboxylic acid may be a polymer composed of a single monomer unit or a copolymer composed of a plurality of monomer units.

  In addition, when using a polyester resin in an aqueous solution as a coating solution, a compound containing a sulfonate group or a compound containing a carboxylate group is copolymerized in order to make the polyester resin water-soluble or water-dispersible. It is preferable to do.

  Examples of the compound containing a carboxylate group include trimellitic acid, trimellitic anhydride, pyromellitic acid, pyromellitic anhydride, 4-methylcyclohexene-1,2,3-tricarboxylic acid, trimesic acid, 1,2, 3,4-butanetetracarboxylic acid, 1,2,3,4-pentanetetracarboxylic acid, 3,3 ′, 4,4′-benzophenonetetracarboxylic acid, 5- (2,5-dioxotetrahydrofurfuryl) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid, 5- (2,5-dioxotetrahydrofurfuryl) -3-cyclohexene-1,2-dicarboxylic acid, cyclopentanetetracarboxylic acid, 2,3 , 6,7-Naphthalenetetracarboxylic acid, 1,2,5,6-naphthalenetetracarboxylic acid, ethylene glycol bis trimellitate 2,2 ′, 3,3′-diphenyltetracarboxylic acid, thiophene-2,3,4,5-tetracarboxylic acid, ethylenetetracarboxylic acid, etc., or alkali metal salts, alkaline earth metal salts, ammonium salts thereof However, it is not limited to these.

  Examples of the compound containing a sulfonate group include sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfoisophthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid, sulfo-p-xylylene glycol, 2-sulfo -1,4-bis (hydroxyethoxy) benzene or the like, or alkali metal salts, alkaline earth metal salts, and ammonium salts thereof can be used, but are not limited thereto.

  In the present invention, modified polyester copolymers such as block copolymers modified with acrylics, urethanes, epoxies, and the like can also be used as the polyester resin.

  In the polylactic acid film of the present invention, polyester resins that can be preferably used include terephthalic acid, isophthalic acid, sebacic acid, trimellitic acid as the acid component, ethylene glycol, diethylene glycol, 1,4-butanediol as the glycol component, Examples thereof include a copolymer selected from neopentyl glycol.

  Among the polyesters described above, in the polylactic acid-based film of the present invention, it is more preferable to use a compound containing the carboxylic acid group such as trimellitic acid, which is preferably used in a laminated coating film on polyethylene terephthalate. Polyesters containing a sulfonate group such as sodium sulfoisophthalic acid are not preferred because coating spots and a decrease in transparency are observed.

  Further, as a method for obtaining a polyester resin having a large amount of carboxylic acid at the terminal and / or side chain, JP-A-54-46294, JP-A-60-209073, JP-A-62-240318, JP-A-53-26828, JP-A-53-26829, JP-A-53-98336, JP-A-56-116718, JP-A-61-124684, JP-A-62-240318 Although it can be produced from a resin obtained by copolymerization of a trivalent or higher polyvalent carboxylic acid described in Japanese Patent Publication No. Gazette, etc., other methods may be used.

  Further, the intrinsic viscosity of the polyester resin used in the B layer according to the present invention is not particularly limited, but is preferably 0.3 dl / g or more, more preferably 0.35 dl / g or more in terms of adhesiveness, Most preferably, it is 0.4 dl / g or more. The glass transition point (Tg) of the polyester resin is preferably 0 to 130 ° C, more preferably 10 to 85 ° C. When Tg is less than 0 ° C., for example, heat-resistant adhesion is poor or a blocking phenomenon occurs. Conversely, when it exceeds 130 ° C., the stability and water dispersibility of the resin are inferior and transparency may be lowered. Therefore, it is not preferable.

  The urethane resin used in the B layer in the present invention is not particularly limited as long as it is a water-soluble or water-dispersible urethane resin having an anionic group, and as a main component, a polyol compound and a polyisocyanate compound are used. It is obtained by copolymerization.

  As the urethane resin, there can be used a urethane resin whose affinity for water is increased by introduction of a carboxylate group, a sulfonate group, or a sulfuric acid half ester base. The content of carboxylate group, sulfonate group, or sulfuric acid half ester base is preferably 0.5 to 15% by weight.

  Examples of the polyol compound include polyethylene glycol, polypropylene glycol, polyethylene / propylene glycol, polytetramethylene glycol, hexamethylene glycol, hexamethylene glycol, tetramethylene glycol, 1,5-pentanediol, diethylene glycol, triethylene glycol, polycaprolactone. Polyhexamethylene adipate, polytetramethylene adipate, trimethylolpropane, trimethylolethane, glycerin, acrylic polyol, and the like can be used.

  Examples of the polyisocyanate compound include tolylene diisocyanate, hexamethylene diisocyanate, phenylene diisocyanate, diphenylmethane diisocyanate, an adduct of tolylene diisocyanate and trimethylol propane, an adduct of hexamethylene diisocyanate and trimethylol ethane, and the like. it can.

  Here, the main structural components of the urethane resin may contain a chain extender, a crosslinking agent, and the like in addition to the polyol compound and the polyisocyanate compound.

  As the chain extender or crosslinking agent, ethylene glycol, propylene glycol, butanediol, diethylene glycol, ethylenediamine, diethylenetriamine, or the like can be used.

  The urethane resin having an anionic group is, for example, a method of using a compound having an anionic group for polyol, polyisocyanate, chain extender, etc., and reacting a compound having an anionic group with an unreacted isocyanate group of the produced urethane resin. However, it is not particularly limited, but can be produced by using a method of reacting a specific compound with a group having active hydrogen of a urethane resin.

  In addition, examples of the urethane resin having an anionic group include a polyol having a molecular weight of 300 to 20000, a polyisocyanate, a chain extender having a reactive hydrogen atom, a group that reacts with an isocyanate group, and a compound having at least one anionic group. A resin consisting of

  The anionic group in the urethane resin is preferably used as a sulfonic acid group, a carboxylic acid group, or an ammonium salt, lithium salt, sodium salt, potassium salt or magnesium salt thereof, and particularly preferably a sulfonic acid group.

  The amount of the anionic group in the urethane resin is preferably 0.05% by weight to 8% by weight. If it is less than 0.05% by weight, the water dispersibility of the urethane resin tends to be poor, and if it exceeds 8% by weight, the water resistance and blocking resistance of the resin tend to be poor.

  In the polylactic acid-based film of the present invention, among the acrylic resin, polyester resin, and urethane resin, an acrylic resin is particularly preferable for achieving high light transmittance and transparency. When an acrylic resin is used, reflection and scattering of light at the interface between polylactic acid and acrylic resin can be further suppressed, and high transparency can be achieved. Furthermore, it is preferable to use an acrylic resin because it has the inhibitory properties of lactide oligomers in the polylactic acid film and the ability to prevent precipitation on the surface.

  Further, the B layer can be used by mixing any two or three of acrylic resin, polyester resin, and urethane resin. In particular, considering the adhesiveness with the A layer, a combination of mixing an acrylic resin and a urethane resin, or an acrylic resin and a polyester resin is preferable. In this case, the mixing ratio of both resins can be arbitrarily selected. A relatively large amount is preferable. In this case, the mixing ratio of the acrylic resin is preferably 60% by weight or more, more preferably 70% by weight or more.

  In the B layer of the present invention, it is possible to use a mixture of a crosslinking agent in the resin. The crosslinking agent is not particularly limited as long as it can undergo a crosslinking reaction with a functional group present in the above-described resin, for example, a carboxyl group, a hydroxyl group, a methylol group, an amide group, etc. Melamine-based crosslinking agent, oxazoline-based crosslinking agent, isocyanate-based crosslinking agent, aziridine-based crosslinking agent, epoxy-based crosslinking agent, methylolized or alkylolized urea-based, acrylamide-based, polyamide-based resin, amide-epoxy compound, various silane couplings Agents, various titanate coupling agents and the like can be used. In particular, a melamine-based crosslinking agent and an oxazoline-based crosslinking agent can be suitably used from the viewpoints of compatibility with the resin and adhesiveness.

  The melamine-based crosslinking agent used in the present invention is not particularly limited, but is partially or completely etherified by reacting melamine, a methylolated melamine derivative obtained by condensing melamine and formaldehyde, or a methylolated melamine with a lower alcohol. A compound or a mixture thereof can be used. Moreover, as a melamine type crosslinking agent, a monomer, the condensate which consists of a multimer more than a dimer, or a mixture thereof can be used. As the lower alcohol used for etherification, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butanol, isobutanol and the like can be used. The functional group has an imino group, a methylol group, or an alkoxymethyl group such as a methoxymethyl group or a butoxymethyl group in one molecule, and an imino group type methylated melamine resin, a methylol group type melamine resin, or a methylol group type. Examples include methylated melamine resins and fully alkyl type methylated melamine resins. Among these, an imino group type melamine resin and a methylolated melamine resin are preferable, and an imino group type melamine resin is most preferable. Furthermore, an acidic catalyst such as p-toluenesulfonic acid may be used in order to promote thermal curing of the melamine-based crosslinking agent.

  The oxazoline-based crosslinking agent used in the present invention is not particularly limited as long as it has an oxazoline group as a functional group in the compound, but includes at least one monomer containing an oxazoline group, and What consists of an oxazoline group containing copolymer obtained by copolymerizing at least 1 type of another monomer is preferable.

  Monomers containing an oxazoline group include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-Isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline, and the like can be used, and one or a mixture of two or more thereof can also be used. Of these, 2-isopropenyl-2-oxazoline is preferred because it is easily available industrially.

In the oxazoline-based cross-linking agent, the at least one other monomer used for the monomer containing the oxazoline group is not particularly limited as long as it is a monomer copolymerizable with the monomer containing the oxazoline group. Acrylates or methacrylates such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, acrylate-2-ethylhexyl, methacrylate-2-ethylhexyl, etc. Unsaturated carboxylic acids such as acid, methacrylic acid, itaconic acid and maleic acid, unsaturated nitriles such as acrylonitrile and methacrylonitrile, acrylamide, methacrylamide, N-methylolacrylamide, N-methylol methacrylate Contains unsaturated amides such as amides, vinyl esters such as vinyl acetate and vinyl propionate, vinyl ethers such as methyl vinyl ether and ethyl vinyl ether, olefins such as ethylene and propylene, vinyl chloride, vinylidene chloride and vinyl fluoride. Halogen- [alpha], [beta] -unsaturated monomers, [alpha], [beta] -unsaturated aromatic monomers such as styrene and [alpha] -methylstyrene can be used, and these should be used alone or in a mixture of two or more. You can also.

  In the B layer according to the present invention, the resin and the cross-linking agent can be mixed and used in an arbitrary ratio, but in order to express the effect of the present invention more remarkably, the cross-linking agent is used with respect to 100 parts by weight of the resin. The solid content is preferably 2 to 50 parts by weight, more preferably 3 to 25 parts by weight. When the addition amount of the crosslinking agent is less than 2 parts by weight, the effect of addition is small, and when it exceeds 50 parts by weight, the adhesion tends to be lowered.

  In the layer B, various additives such as an antioxidant, a heat stabilizer, a weather stabilizer, an ultraviolet absorber, an organic lubricant, a pigment, and a dye are used within the range in which the effects of the present invention are not impaired. Organic or inorganic fine particles, fillers, antistatic agents, nucleating agents and the like may be blended.

  The heat shrinkage rate of the polylactic acid film of the present invention when heated at 120 ° C. for 30 minutes is preferably 5% or less in both the longitudinal direction (MD direction) and the width direction (TD) of the film. More preferably, it is -1 to 3% of range. If the heat shrinkage rate is large, the film is greatly shrunk during film processing such as printing and molding, and if it is smaller than this range, the film is stretched during heat processing, and in any case, defects such as wrinkles are not preferable.

  The method for setting the heat shrinkage rate of the film in the above range is not particularly limited, but can be achieved by heat treatment at a relatively high temperature not higher than the melting point (Tm) of the film for about 1 to 60 seconds. is there. For example, heat treatment is performed at a temperature of Tm−50 ° C. to Tm−20 ° C., particularly preferably at a temperature of Tm−35 ° C. to Tm−25 ° C. while relaxing the film in a range of 10% or less in advance in the film manufacturing process. It is preferable. Moreover, the method etc. which heat-process at the temperature of Tm-80 degreeC-Tm-20 degreeC, etc. are mentioned, relaxing the film once wound after film forming in heating oven. Within the above temperature range, the higher the heat treatment temperature, the lower the absolute value of the heat shrinkage rate, and the flatness during heating can be improved. In film formation, it is not preferable because it is easily broken by heating. On the other hand, the longer the heat treatment time, the lower the absolute value of the thermal shrinkage rate, which is preferable. In addition to characteristics such as thermal dimensional stability, the length of the heat treatment apparatus, productivity (production rate), etc. Is determined in consideration of the above, and is generally in the range of about 5 to 30 seconds.

  The polylactic acid film of the present invention preferably has a static friction coefficient in the range of 0.05 to 0.8. More preferably, it is the range of 0.1-0.6. When the static friction coefficient exceeds the above range or less than the above range, the handleability deteriorates, which is not preferable because it causes wrinkles and winding deviations during printing.

  The surface roughness Ra of at least one surface of the polylactic acid film of the present invention is preferably in the range of 0.1 to 100 nm. Here, the surface roughness Ra is a center line average roughness, and this definition is shown in documents such as “Evaluation Method of Surface Roughness” by Jiro Nara (General Technology Center, 1983). The range of Ra is more preferably 5 to 50 nm, and particularly preferably 15 to 40 nm. In particular, for a decorative sheet for which gloss is desired, the surface is preferably smooth, that is, the surface roughness Ra is preferably small. On the other hand, when the surface roughness is small and particularly less than the above range, it is not preferable because scratches are easily generated on the surface during processing and use.

  In addition, in achieving the above static friction coefficient and surface roughness, the A-layer polylactic acid resin constituting the film of the present invention, or the resin constituting the B-layer contains inorganic particles, organic particles, organic lubricants, etc. Can be contained. In particular, it is preferable to add inorganic particles and organic particles in order to develop excellent printability and ink adhesion.

  Examples of inorganic particles that can be preferably added include wet or dry silica, alumina, clay, mica, titanium oxide, calcium carbonate, calcium phosphate, kaolin, talc, zirconia, and spinel. Examples of the organic particles include those having acrylic acid polymers, polystyrene and the like as constituent components. Among these, inorganic particles such as silica and alumina can be preferably used from the viewpoint of dispersibility. The particle diameters of these inorganic particles and organic particles are arbitrary as long as they do not impair the object of the present invention, but are preferably 0.01 to 5 μm, more preferably 0.1 to 3 μm. When the particle size exceeds this size, the transparency is greatly lowered, and in particular, the light transmittance may be lowered due to light shielding. Moreover, if it is less than this magnitude | size, it will be difficult to acquire the effect as a lubricant.

  Further, the amount of inorganic particles and organic particles added to the A layer is preferably in the range of 0.001 to 5% by weight, more preferably 0.01 in order to achieve the transparency which is the object of the present invention. It is in the range of ˜0.08% by weight. Moreover, the preferable addition amount to B layer is 0.01 to 10 weight%, More preferably, it is 0.01 to 1 weight%. When the amount of particles added to the A layer and the B layer exceeds the above range, haze increases due to increased light scattering, and even when adjacent particles are overlapped, the same light as when the above large particles are added. This is not preferable because it may cause a decrease in light transmittance.

  Preferred organic lubricants include amide organic lubricants such as ethylene bis stearamide, monoester organic lubricants, fatty acid salts, silicon compounds, carnauba wax, and candelilla wax. The organic lubricant is excellent in dispersibility with respect to the polylactic acid resin as the base polymer, and if a material having a refractive index close to that of the polylactic acid resin is selected, easy lubricity can be imparted without relatively lowering the transparency. Among the above compounds, an amide organic lubricant is particularly preferably used from the viewpoint of dispersibility. A preferable amount of the organic lubricant added to the A layer is in the range of 0.01 to 0.5% by weight, and particularly preferably in the range of 0.01 to 0.1% by weight. Moreover, as a preferable addition amount to B layer, it is the range of 0.1 to 10 weight%.

  If the addition amount of the organic lubricant is large within the above range, the coefficient of static friction is lowered and the scratch resistance is improved, but the printability, the adhesion with the ink, and the adhesion of the A layer / B layer may be lowered. Therefore, in the polylactic acid-based film of the present invention, it is preferable that no organic lubricant is added or the upper limit value is not exceeded. Moreover, the said lower limit is addition amount required in order to express the effect of an organic lubricant.

  The lubricant may be added only to the A layer or only to the B layer, or may be added to both the A layer and the B layer. In particular, it is preferable to add only the B layer without adding a lubricant to the A layer, because the internal haze of the film is lowered, transparency is increased, and the static friction coefficient which is important in handling can be reduced.

  The polylactic acid-based film of the present invention preferably has a plasticizer, an antioxidant, an antistatic agent, an ultraviolet absorber, and an anti-coloring agent in the range of 30% by weight or less, particularly preferably in the range of 5% by weight or less. Various additives and modifiers such as aliphatic polyesters, aromatic polyesters, and polyolefins may be contained. From the viewpoint of improving the heat resistance of the polylactic acid-based film, it is possible to preferably add a polymer such as a cellulose derivative such as cellulose acetate or an acrylic resin such as polymethyl methacrylate.

  The polylactic acid film of the present invention needs to have a light transmittance of 90% or more. More preferably, it is 92% or more, and particularly preferably 94% or more. Moreover, it is preferable that the polylactic acid-type film of this invention is 10% or less of haze. More preferably, it is 5% or less, and particularly preferably 3% or less. When the light transmittance is high and the haze is low, the transparency is good. Therefore, the beauty of the decorative sheet is improved, and the printing visibility is good. Further, the glossiness of the film is preferably in the range of 120 to 180%, more preferably in the range of 130 to 180%.

  In order to set the light transmittance, haze, and glossiness within the above ranges, an additive having a size of 0.1 μm or more, a dispersion diameter, a modifier, or a refraction, added to the layer constituting the film surface. For example, a method of suppressing the addition amount of incompatible dissimilar polymers having greatly different rates, for example, 1% by weight or less with respect to the polylactic acid resin can be used.

  The method of forming the B layer is not particularly limited, but is a method of combining the A layer and the B layer by melt extrusion, or a method of applying the B layer coating liquid on the A layer during the film production process ( In-line coating), a method in which the A layer is once produced alone and wound up in a roll shape, and then the B layer is applied (offline coating) is a general technique, and further, the A layer and the B are bonded via an adhesive. Examples thereof include a method by dry lamination for laminating layers, a method by heat lamination, and a method by extrusion lamination.

  As a preferable method, the method using in-line coating is preferable in view of the transparency and adhesiveness of the polylactic acid film of the present invention and considering the productivity.

  In the present invention, before forming the B layer by a technique such as coating or lamination, the surface of the A layer is subjected to a corona discharge treatment or the like, and the wetting tension of the surface of the base film is preferably 40 mN / m or more. Preferably it is 44 mN / m or more, since the adhesiveness between the A layer and the B layer can be improved.

  Although the thickness of B layer is not specifically limited, Usually, the range of 0.01-5 micrometers is preferable, More preferably, it is 0.02-2 micrometers, Most preferably, it is 0.05 micrometer-0.5 micrometer. If the thickness of the laminated film is less than the above range, it may be too thin, resulting in poor adhesion. On the other hand, if the above range is exceeded, no significant improvement in adhesiveness is observed, and the time for drying and solidifying the B layer applied in liquid form must be set longer, resulting in a decrease in coating speed. This is not preferable because the productivity also decreases.

  Various coating methods such as a reverse coating method, a gravure coating method, a rod coating method, a bar coating method, a Mayer bar coating method, a die coating method, and a spray coating method can be used as the coating method for the B layer.

  In the present invention, it is possible to preferably perform an electric discharge machining treatment in a nitrogen atmosphere on the B layer formed by coating in terms of improving adhesiveness. The nitrogen atmosphere may be an atmosphere in which nitrogen-containing functional groups can be effectively introduced into the treated surface by electric discharge machining, but preferably has an oxygen concentration of 15% by volume or less, more preferably 10% by volume or less. Under atmosphere.

  The polylactic acid film of the present invention is preferably a uniaxially oriented film or a biaxially oriented film in terms of heat resistance and stability over time. Although the manufacturing method of these oriented films is not particularly limited, an example of a method for forming the B layer by in-line coating on the melt-extruded A layer is shown below.

  The additive is diluted and mixed with a master pellet of an additive such as polylactic acid resin and inorganic particles, and dried at an appropriate temperature (for example, a temperature of about 60 to 140 ° C.) to sufficiently remove water (300 ppm or less, preferably 100 ppm or less After that, it is melted in a suitable condition of about 180 to 250 ° C. in an extruder to form a polymer stream. The molten polymer is passed through a filter having a filtration accuracy of about 5 to 50 μm, and the polymer is filtered to remove coarse foreign matters. The polymer after filtration is extruded into a sheet form from a slit-shaped base, and is brought into close contact with a casting drum whose temperature is controlled to about 10 to 50 ° C. by a technique such as an electrostatic application method to cool and solidify to produce an unstretched film. This film is continuously heated and stretched about 1.1 to 5 times in the longitudinal direction, and the coating solution is continuously applied to the uniaxially stretched film. The film to which the coating solution has been applied is subsequently introduced into the tenter and stretched by 2 to 6 times in the lateral direction while being held by a clip, and is suitably at a temperature of about 80 to 150 ° C., more preferably about 135 to 150 ° C. Then, heat treatment is performed to obtain a stretched film.

  Although it does not specifically limit as thickness (sum of A layer thickness and B layer thickness) of the polylactic acid-type film of this invention, Usually, about 1-500 micrometers, Preferably it is about 10-200 micrometers, Most preferably, it is 20-150 micrometers. Degree. Outside the above range, moldability is deteriorated, which is not preferable. In particular, when used for a molded transfer foil, the range of about 10 to 50 μm is preferred with emphasis on moldability, and when used for a decorative sheet, the range of 50 to 200 μm is preferred in order to give the surface a gloss and depth.

  Moreover, it is preferable to have the filtration process of the molten polymer by a filter in the manufacturing process of a film from the point of the beauty of a polylactic acid-type film, and printing omission prevention. By filtering with a filter, coarse foreign matter and modified polymer are sufficiently removed, and not only coarse protrusions and fish eyes that cause problems in film quality are prevented, but also tearing is reduced in the production process, and stable film formation becomes possible.

  In addition, the polylactic acid film of the present invention can be used by printing on the surface of the B layer. However, in order to further improve the design properties, processing other than printing such as vapor deposition, embossing, and hairline processing is performed. Is possible. Moreover, since the polylactic acid-type film of this invention has a favorable moldability compared with existing biaxially oriented films such as polyethylene terephthalate, it can be preferably used for decorative molding applications.

  The polylactic acid-based film of the present invention is particularly suitable as a decorative sheet and a decorative sheet because it has particularly good printability and transparency.

  Although the structure of a decoration sheet is not specifically limited, A preferable structural example is shown in FIG. A configuration in which a printing layer is disposed on the polylactic acid-based film of the present invention (FIG. 1), a configuration in which a printing layer is disposed on the polylactic acid-based film of the present invention, and a base sheet is further disposed on the printing layer side (FIG. 2). A structure in which a surface functional film layer having other functions such as antistatic, scratch prevention and dirt prevention is disposed on the surface of the structure of FIG. 2 (FIG. 3), and further between the surface functional film layer and the A layer of the structure of FIG. The structure (FIG. 4) etc. which arrange | positioned B layer to can be mentioned. Between these layers, another layer can be formed for the purpose of providing adhesion between layers and other functions.

  The base sheet is used for the purpose of concealing the color and unevenness of the back plate and molded product when the decorative sheet is bonded to another substrate, and the material is particularly limited. However, preferred examples include paper, a film (sheet) made of a thermoplastic resin, a woven fabric, a nonwoven fabric, a metal plate such as iron, aluminum, and copper, and a metal foil. In order to conceal the above-mentioned color and unevenness, a film made of a thermoplastic resin colored with paper and pigments or dyes is particularly preferable.

  The paper used as the base sheet is not particularly limited, but Kent paper, high-quality paper, kraft paper, pure white paper, service paper, glassine paper, rayon paper, art paper, coated paper, cast coated paper, embossed paper And existing products such as

  Although it does not specifically limit as a film used for a base material sheet, The polylactic acid-type resin is preferable from the point of recycling of a decoration sheet. In particular, it is preferable to use a colored polylactic acid film imparted with concealing properties by adding a white pigment such as titanium oxide and / or forming voids in the inner layer.

  The surface functional film layer can be formed by a technique such as off-line coating or in-line coating for the purpose of preventing charging, preventing scratches, preventing dirt, and increasing glossiness.

  The printing layer is formed by an existing printing method such as gravure printing, offset printing, flexographic printing, or screen printing, or an existing printing ink.

  In addition, since the polylactic acid film of the present invention not only has good adhesion to ink, but also has good adhesion when bonded via an adhesive, it can be applied directly to a substrate that has been decorated such as printing. It is also possible to use them together.

  The decorative sheet of the present invention can be used, for example, for decoration applications such as automobile interior and exterior materials, electrical appliances, building materials and furniture. More specifically, car instrument panel peripherals, switch peripheral decoration members, switch materials such as electrical appliances, nameplates, labels, signboards, building materials / furniture decorative boards, laminated steel sheets, gaming machine gauge panels, credit cards, etc. The card material is preferably mentioned.

  The decorative sheet can be used by bonding, but the object to be bonded is preferably a plate or molded product made of wood, glass, metal, resin, or a plate or molded product made of a mixture of these materials. Can be mentioned.

  In particular, it can be preferably used for surface decoration such as a fiber board formed by heating and pressing a fiber laminate in which thermoplastic fibers are mixed in a fiber material.

  What is preferable in the fiber-based board is a material in which a polylactic acid resin is used as a thermoplastic fiber used as a binder for a cellulose fiber that is a natural fiber as a fiber material, and the decorative sheet is peeled off when the fiber-based board is recycled. It is particularly preferable because it can be pulverized without being recycled to be reused as a raw material for fiber boards.

  Cellulose fibers used for fiber boards include 1) wood pulp, 2) bagasse, wheat straw, reed, papyrus, bamboo and other grass plant pulp, 3) cotton, 4) kenaf, roselle, Asa, flax, ramie , Bast fibers such as jute and hemp, and 5) leaf vein fibers such as sisal and manila. Among these, the adoption of fibers collected from kenaf belonging to herbs that are annual grasses and grow very quickly and easily in the tropics and temperate regions is an effective use of natural resources, It is preferable from the viewpoint of recycling.

  In addition, the configuration in which the polylactic acid film of the present invention, the decorative sheet of the present invention, and the decorative sheet of the present invention are bonded to the above-described fiber board is composed of a natural material in the majority of the constituent materials. Compared to the case of using a petroleum synthetic resin such as polyethylene terephthalate, it is excellent as an environmentally friendly material.

Hereinafter, the present invention will be further described by examples.
[Measurement method of characteristics]
(1) Surface roughness Using ET-10 manufactured by Kosaka Laboratory, the center line average roughness (Ra) was measured under the conditions of a stylus tip radius of 0.5 μm, a needle pressure of 5 mg, a measurement length of 1 mm, and a cutoff of 0.08 mm. It was measured. The measurement was performed at five points in the longitudinal direction of the film, and the average value was taken as the measured value of the surface roughness.

(2) Total light transmittance The haze meter made from Suga Test Instruments was used and it measured according to JIS-K7105.

(3) Ink adhesion The following three types of inks were applied to the surface of the film B layer to a thickness of 1.5 μm by the roll coating method. Inks A and B were cured with an ultraviolet lamp at an irradiation intensity of 80 W / cm, an irradiation distance of 9 cm, and an irradiation time of 5 seconds. Ink C was dried at 40 ° C. for 30 minutes.

Ink A: Lake Cure SL6100 manufactured by Jujo Chemical Co., Ltd.
Ink B: “FLASH DRY” FD Carton P ink manufactured by Toyo Ink Manufacturing Co., Ltd. Ink C: CAV Meban manufactured by Seiko Advance Co., Ltd.

100 pieces of 1 mm ² crosscuts were put into the formed ink film, cellophane tape made by Nichiban Co., Ltd. was applied on it, and it was reciprocated three times with a load of 19.6 N using a rubber roller, and then 90 ° It peeled to the direction and it determined by the following four-stage evaluation by the number of remaining ink films.

A: 100 (pass)
○: 80 to 99 (pass)
Δ: 50-79 (pass)
X: 0 to 49 (failed).

[Raw material for polylactic acid film]
(Raw material for layer A creation: resin for melt extrusion film formation)
・ Polylactic acid A
A polylactic acid resin having a weight average molecular weight of 200,000, an L-lactic acid component amount of 98.5%, a D-lactic acid component amount of 1.5%, a melting point of 169 ° C., and a carboxyl end group concentration of 35 equivalents / ton.

・ Polylactic acid B
Polylactic acid resin in which silica particles having an average particle size of 1.6 μm and polylactic acid A were mixed at 210 ° C. using a twin screw extruder at a silica concentration of 5% by weight. .

(Raw material for layer B: Coating liquid)
・ Liquid 1 (acrylic A)
The following (A) / (D) / (E) / (F) are blended at a solid content weight ratio of 75/25/5 / 0.5, diluted with water to a solid content concentration of 4% by weight. Acrylic emulsion.

・ Liquid 2 (acrylic B)
An acrylic emulsion containing (A) / (D) shown below at a solid content weight ratio of 75/25 and diluted with water to a solid content concentration of 4% by weight.

・ Liquid 3 (Polyester A)
(B) / (E) / (F) shown below are blended at a solid content weight ratio of 100/5 / 0.5 and diluted with water to a solid content concentration of 4% by weight. .

・ Liquid 4 (Polyester B)
A polyester emulsion in which (B) / (E) / (F) shown below is blended at a solid content weight ratio of 100/5/5 and diluted with water to a solid content concentration of 4% by weight.

・ Liquid 5 (urethane)
A polyurethane prepolymer aqueous dispersion prepared by blending the following (C) / (E) / (F) at a solid content weight ratio of 100/5 / 0.5 and diluting with water to a solid content concentration of 4%. It is.

(A) Acrylic resin:
60% by weight methyl methacrylate
Butyl acrylate 38% by weight
Acrylic acid 1% by weight
N-methylolacrylamide 1% by weight
An aqueous emulsion of the copolymer.

(B) Polyester resin:
Acid component terephthalic acid 60 mol%
Isophthalic acid 14 mol%
Sebacic acid 6 mol%
Trimellitic acid 20 mol%
Diol component Ethylene glycol 28 mol%
Neopentyl glycol 38 mol%
1,4-butanediol 34 mol%
An aqueous dispersion in which the polyester resin comprising the acidic component and the diol is made aqueous with ammonia water.

(C) Urethane resin:
Polybutadiene polyol 70 parts by weight Polyethylene glycol 30 parts by weight Hexamethylene diisocyanate 17 parts by weight Butanone oxime 4.4 parts by weight Dimethylolpropionic acid 3.3 parts by weight Triethylamine An aqueous dispersion of a polyurethane prepolymer having a composition ratio of 2.5 parts by weight.

(D) Antistatic agent:
An aqueous dispersion of polystyrene sulfonate ammonium salt (molecular weight = about 40,000).

(E) Melamine crosslinking agent:
A coating solution obtained by diluting methylolated melamine to a mixed solvent of isopropyl alcohol / water = 10/90 (weight ratio).

(F) Silica particles:
NISSAN CHEMICAL INDUSTRIES, INC .: Snow Tech OL, an aqueous dispersion with an average particle size of 40 nm.

[Creation of polylactic acid film]
(Example 1)
Polylactic acid A was dried at 120 ° C. under a vacuum of 2 KPa or less for 5 hours. The dried resin was supplied to a single screw extruder having a screw diameter of 50 mm and melted at an extruder cylinder temperature of 230 ° C. The molten polymer was passed through a sintered disk filter having a filtration accuracy of 20 μm, then extruded into a film shape at a base temperature of 220 ° C., and casted electrostatically on a mirror drum cooled to 30 ° C. to prepare an unoriented film. Subsequently, the film was continuously stretched 3 times in the longitudinal direction between heating rolls at 80 ° C., and then coating liquid 1 (acrylic A) was applied to both sides of the film with a metabar. Further, the film edge is held by a clip and guided into a tenter, and heated at 78 ° C., stretched by 3.2 times in the lateral direction, and subjected to heat treatment at 140 ° C. for 12 seconds while being relaxed by 2% in the width direction. A polylactic acid film having a total thickness of 150 μm and a thickness of 0.12 μm per one side of the B layer was obtained. Table 1 shows the characteristics of the obtained film. The film was excellent in transparency and ink adhesion.

(Example 2)
The resin to be used was mixed at a weight ratio of polylactic acid A: polylactic acid B = 99: 1. A polylactic acid film having a total thickness of 150 μm and a B layer thickness of 0.12 μm under the same conditions as in Example 1 except that the coating liquid for forming the B layer was changed to the coating liquid 2 (acrylic B) on one side of the film. Got. The film was excellent in both ink adhesion and transparency.

(Example 3)
A polylactic acid film was obtained in the same manner as in Example 2 except that the coating solution was changed to the coating solution 3 (polyester A).

Example 4
After stretching in the longitudinal direction, a polylactic acid film was prepared in the same manner as in Example 2 except that the coating solution was not applied and stretching in the lateral direction was performed.

  The polylactic acid film once wound up in a roll is subjected to corona discharge treatment on one side, coated with coating liquid 3 (polyester A) with a gravure coater and dried, and has a total film thickness of 150 μm and a B layer thickness. A 1.2 μm polylactic acid film was obtained.

(Example 5)
A polylactic acid film was obtained in the same manner as in Example 2 except that the coating solution was changed to coating solution 5 (urethane). In particular, the film was excellent in ink adhesion.

(Comparative Example 1)
The resin used was a mixture of polylactic acid A: polylactic acid B = 96: 4 in a weight ratio. A polylactic acid film was obtained in the same manner as in Example 2 except that the coating solution was changed to the coating solution 4 (polyester B).

(Comparative Example 2)
After stretching in the longitudinal direction, a 150 μm thick polylactic acid film was obtained in the same manner as in Example 1 except that the coating liquid was not applied and the stretching was performed in the lateral direction.

(Reference example)
For comparison with Example 1, a film having a structure in which a polyethylene terephthalate resin was used as the A layer instead of the polylactic acid resin was prepared by the following procedure.

  Polyethylene terephthalate resin (melting point: 256 ° C., no lubricant added, intrinsic viscosity: 0.65 dl / g, carboxyl end group: 25 equivalents / ton) obtained by polycondensation of ethylene glycol and terephthalic acid at 180 ° C. under vacuum conditions of 2 KPa or less And dried for 4 hours. The dried resin was supplied to a single screw extruder having a screw diameter of 50 mm and melted at an extruder cylinder temperature of 285 ° C. The molten polymer was passed through a sintered disk filter having a filtration accuracy of 20 μm, subsequently extruded into a film shape at a base temperature of 285 ° C., and electrostatically cast on a mirror drum cooled to 30 ° C. to prepare a non-oriented film. Subsequently, the film was continuously stretched 3.3 times in the longitudinal direction between heating rolls at 98 ° C., and then coating liquid 1 (acrylic A) was applied to both surfaces of the film with a metabar. Further, the film edge is held by a clip and guided into a tenter, heated at a temperature of 120 ° C., stretched 3.5 times in the lateral direction, and subjected to heat treatment at 220 ° C. for 12 seconds while relaxing 3% in the width direction. A polyethylene terephthalate film having a total thickness of 150 μm and a thickness of 0.12 μm per one side of the B layer was obtained. Both transparency and ink adhesion are good, but the light transmittance is inferior compared to Example 1 in which a film is similarly formed with a polylactic acid resin.

[Creation and evaluation of decoration sheet]
As a reference film for evaluation, corona discharge treatment was performed on one side of “Lumirror” T60 (thickness: 188 μm), and the coating liquid coating liquid 2 was applied and dried with a gravure coater to form a B layer having a thickness of 1.2 μm. A film was prepared.

Using the above-described ink A on the surface of the B layer of the polylactic acid film prepared in Examples 1 to 5 and Comparative Examples 1 and 2 and the above-mentioned reference film (any one side for the film of Comparative Example 2) 4 Color silk printing was applied. Furthermore, a decorative sheet is prepared by bonding high-quality paper (weighing 128 g / m ² , thickness 0.13 mm) on the printed surface by dry lamination (adhesive: manufactured by Dainippon Ink, Dick Dry LX-75A / KW-40). did.

  Compared with the decorative sheet obtained from the printed matter of the reference sample, the appearance (transparency, clearness of printing) was compared, and the same or better were evaluated as “◯” and the inferior one as “X”.

  The films of Examples 1 to 3 are excellent as a decorative sheet because of excellent finish, no printing omission, ink peeling, etc., and excellent transparency. In addition, Example 1 is particularly excellent in transparency and texture.

  Since the film of Comparative Example 1 is inferior in transparency, it is inferior in the clearness of printing and is unsuitable as a decorative sheet of the present invention.

  Further, since the film of Comparative Example 2 is inferior in ink adhesion, the ink is easily peeled off during laminating and the like, and as a result, the appearance is deteriorated and is not suitable as the decorative sheet of the present invention.

  The polylactic acid-type film of this invention is related with the polylactic acid-type film which has favorable adhesiveness with printing ink and various coatings. In particular, since the polylactic acid-based film of the present invention is excellent in printability, it can be used as a decorative sheet or decorative sheet for decorating the surface of a substrate composed of a wooden substrate, a resin molded product, a resin sheet, a metal steel plate, etc. after printing. Suitable for use. The decorative sheet of the present invention can be suitably used for applications requiring a high degree of design such as building materials, electrical products, automobile parts, cards, and gaming machines.

The cross section of the typical structure of the decoration sheet | seat of this invention is shown. The cross section of the typical structure of the decoration sheet | seat of this invention is shown. The cross section of the typical structure of the decoration sheet | seat of this invention is shown. The cross section of the typical structure of the decoration sheet | seat of this invention is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 A layer: The layer which consists of polylactic acid-type resin 2 B layer: Easy-adhesion layer 3 Polylactic acid-type film 4 Printing layer 5 Base material sheet 6 Surface functional film layer 7 The surface of a decoration sheet

Claims (5)

A layer (B layer) composed mainly of at least one resin selected from the group consisting of an acrylic resin, a polyester resin, and a urethane resin is laminated on at least one side of a layer (A layer) made of a polylactic acid resin. A polylactic acid film having a light transmittance of 90% or more. The polylactic acid film according to claim 1, wherein the content of the lubricant in the polylactic acid resin in the A layer is 0.08% by weight or less. The polylactic acid film according to claim 1 or 2, wherein at least one surface has a two-dimensional surface roughness (Ra) of 0.1 to 100 nm. The polylactic acid film according to claims 1 to 3, which is used as a decorative sheet. The decoration sheet formed by arrange | positioning at least a printing layer and a base material sheet in order to the polylactic acid-type film of Claims 1-3.

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