JP4935098B2 - Polylactic acid-based resin laminate sheet and molded body comprising the same - Google Patents

Description

  The present invention is a polylactic acid-based resin laminated sheet with good moldability for obtaining molded products such as various shape-preserving tools, containers and the like that require heat resistance, transparency, and gloss, and is composed thereof. It relates to a molded body.

  In recent years, with the growing awareness of the environment, the disposal of plastic products has been attracting attention. About shape retainers used for display and packaging of various products, and containers such as food trays and beverage cups Also, those using various biodegradable plastic sheets have been developed. Among them, polylactic acid is particularly attracting attention as a promising material because it has a high glass transition point of about 60 ° C. and is transparent as a biodegradable plastic.

  However, the glass transition point is about 20 ° C. lower than that of conventional petroleum-derived raw materials such as polyethylene terephthalate, and there is a problem that heat resistance is insufficient when each current application is replaced with polylactic acid.

  As means for solving this problem, a technique for imparting heat resistance has been proposed by adding a crystal nucleating agent to the polylactic acid resin to enhance the crystallinity of the polylactic acid resin.

  For example, a technology (Patent Documents 1 and 2) is known in which a polylactic acid resin containing a crystal nucleating agent is heat-treated at the time of molding or after molding to improve crystallinity. Therefore, there has been a problem that the surface of the molded body is crystallized by the heat treatment, and transparency and gloss are lowered.

  In addition, a technique (Patent Document 3) is known in which a polylactic acid resin, a lactic acid-based polyester mainly composed of an aliphatic polyester and a lactic acid component, and a sheet composed of a nucleating agent are heat-treated to obtain a molded product with improved crystallinity. . However, even with this technique, although heat resistance is improved, there is still a problem that transparency and gloss are lowered due to the crystallization of the sheet surface.

Furthermore, the outer layer is made of a polylactic acid resin, a lactic acid polyester mainly composed of an aliphatic polyester and a lactic acid component, and the inner layer is made of a two-kind / three-layer sheet composed of a polylactic acid resin containing a transparent nucleating agent. A technique (Patent Document 4) for obtaining a polylactic acid sheet having high resistance and bending strength has been proposed. However, the technique disclosed here has a problem that the heat resistance is insufficient because the sheet is not heat-treated.
JP-A-9-278991 JP-A-11-5849 JP 2004-149692 A JP 2005-119062 A

  In view of the background of such prior art, the present invention provides a polylactic acid-based resin laminate sheet and a molded body having good moldability, which can obtain a molded article having excellent heat resistance, transparency, and glossiness. Is.

In order to solve the above problems, the present invention employs the following means. That is, the polylactic acid-based resin laminate sheet of the present invention is as follows.
A laminated sheet comprising a polylactic acid resin composition,
The laminated sheet is composed of a layer A containing a crystal nucleating agent and a layer B substantially containing no crystal nucleating agent,
It is a three-layer structure in which layer A is an inner layer and layer B is both outer layers,
The ratio of the thickness of the layer A to the total thickness of the laminated sheet is 80.1 % to 99.9%. Further, the laminated sheet has a configuration in which the outermost layer of the laminated sheet is a layer B on both sides. Has a laminated structure,
The crystal nucleating agent is selected from aliphatic carboxylic acid amides, aliphatic carboxylates, aliphatic alcohols, aliphatic carboxylic acid esters, aliphatic / aromatic carboxylic acid hydrazides, melamine compounds, and phenylphosphonic acid metal salts. At least one,
A polylactic acid-based resin laminate sheet comprising 95 mol% or more of L-form or 95 mol% or more of D-form in the total lactic acid component of the polylactic acid-based resin.

  ADVANTAGE OF THE INVENTION According to this invention, the polylactic acid-type resin laminated sheet with favorable moldability for obtaining the molded object which was excellent in all heat resistance, transparency, and glossiness can be obtained. The polylactic acid-based resin laminated sheet obtained by the present invention requires various shape retainers such as blister packs, containers such as food trays and beverage cups that require heat resistance and transparency, heat resistance and glossiness It can be preferably used for molded articles such as display bottles of beverage vending machines.

  The present invention, as a result of intensive studies on the polylactic acid resin sheet having good moldability that can obtain a molded article excellent in the above-mentioned problems, that is, heat resistance, transparency, and glossiness, has good moldability. The polylactic acid resin sheet is made of a resin composition for producing a polylactic acid resin sheet containing a normal crystal nucleating agent, that is, the layer A containing a crystal nucleating agent substantially contains a crystal nucleating agent. When the layers B made of the resin composition that is not used are laminated so as to be sandwiched, it has been found that such problems can be solved all at once.

  That is, the present inventors investigated that the polylactic acid-based resin sheet containing a normal crystal nucleating agent forms fine irregularities on the surface of the sheet when crystallized. By finding out that the glossiness is greatly reduced and adopting the specific means to construct a specific laminated sheet, we succeeded in eliminating such fine irregularities for the first time and were able to solve the above problems. is there.

  The weight average molecular weight of the polylactic acid resin used in the present invention is preferably from 50,000 to 500,000, more preferably from 100,000 to 500,000 in order to satisfy appropriate film formation, stretchability and practical mechanical properties. 250,000. In addition, a weight average molecular weight here means the molecular weight which measured with the chloroform solvent by the gel permeation chromatography, and was calculated by the polymethylmethacrylate conversion method.

  The polylactic acid resin used in the present invention is a polymer mainly composed of a structure that can be obtained using L-lactic acid and / or D-lactic acid as a raw material, but includes other copolymerization components other than lactic acid. You may go out. Other monomers include ethylene glycol, propylene glycol, butanediol, heptanediol, hexanediol, octanediol, nonanediol, decanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, glycerin, pentane. Glycol compounds such as erythritol, bisphenol A, polyethylene glycol, polypropylene glycol and polytetramethylene glycol, oxalic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, malonic acid, glutaric acid, cyclohexanedicarboxylic acid, terephthalic acid , Isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, bis (p-carboxyphenyl) methane, anthracene dicarboxylic acid, 4,4′-diphenyl ether dicarboxylic acid, -Dicarboxylic acids such as sodium sulfoisophthalic acid, 5-tetrabutylphosphonium isophthalic acid, glycolic acid, hydroxypropionic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxycaproic acid, hydroxybenzoic acid and other hydroxycarboxylic acids, caprolactone, valerolactone, Examples include lactones such as propiolactone, undecalactone, and 1,5-oxepan-2-one. The copolymerization amount of the other copolymerization component is preferably 0 to 30 mol%, more preferably 0 to 10 mol%, based on all monomer components.

  In the present invention, in order to obtain a molded product having particularly high heat resistance, it is preferable to use a polylactic acid resin having a high optical purity of the lactic acid component. That is, among the total lactic acid components of the polylactic acid-based resin, the L isomer is preferably contained in an amount of 80 mol% or more, or the D isomer is preferably contained in an amount of 80 mol% or more, and the L isomer is contained in an amount of 90 mol% or more. More preferably, the D isomer is contained in an amount of 90 mol% or more, and the L isomer is contained in an amount of 95 mol% or more, or the D isomer is contained in an amount of 95 mol% or more.

  The melting point of the polylactic acid resin used in the present invention is not particularly limited, but is preferably 120 ° C. or higher, and more preferably 150 ° C. or higher. The melting point of such a polylactic acid-based resin is usually increased by increasing the optical purity of the lactic acid component, and the polylactic acid resin having a melting point of 120 ° C. or higher contains 90 mol% or more of the L form or 90 parts of the D form. The polylactic acid resin having a melting point of 150 ° C. or more can be obtained by containing 95 mol% or more of the L form or 95 mol% or more of the D form.

The layer A and / or layer B of the polylactic acid-based resin laminate sheet of the present invention may be mixed with a resin other than the polylactic acid-based resin, if necessary, within a range that does not impair the object and effect of the present invention. Good. For example, thermoplastic resins such as polyacetal, polyethylene, polypropylene, polyamide, poly (meth) acrylate, polyphenylene sulfide resin, polyether ether ketone resin, polyester, polysulfone, polyphenylene oxide, polyimide, polyetherimide, polyvinyl resin, phenol resin, Thermosetting resin such as melamine resin, polyester resin, silicone resin, epoxy resin, ethylene / glycidyl methacrylate copolymer, polyester elastomer, polyamide elastomer, ethylene / propylene terpolymer, ethylene / butene-1 copolymer, etc. Thermoplastic resins can be used. Among these, the poly (meth) acrylate resin has a glass transition temperature of 60 ° C. because it has good compatibility with the polylactic acid-based resin, improves the glass transition temperature of the resin composition after mixing, and improves high-temperature rigidity. The polyvinyl resin which becomes the above is preferable.
The poly (meth) acrylate has at least one monomer selected from acrylate and methacrylate as a structural unit, and two or more monomers may be copolymerized and used. Examples of the acrylate and methacrylate used to constitute the poly (meth) acrylate include acrylates such as methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, cyanoethyl acrylate, and cyanobutyl acrylate, and methyl methacrylate and ethyl. Although methacrylates such as methacrylate, cyclohexyl methacrylate, and 2-hydroxyethyl methacrylate are exemplified, polymethyl methacrylate is preferably used for imparting higher high-temperature rigidity and moldability.

  Specific examples of the polyvinyl resin having a glass transition temperature of 60 ° C. or higher include polystyrene, poly (4-acetylstyrene), poly (2-methylstyrene), poly (3-methylstyrene), and poly (4-methylstyrene). , Poly (4-methoxystyrene), poly (4-hydroxystyrene) (polyvinylphenol), poly (2-hydroxymethylstyrene), poly (3-hydroxymethylstyrene), poly (4-hydroxymethylstyrene), etc. Styrene polymer, and poly (benzoyloxyethylene), poly (cyclohexanoyloxyethylene), poly (4-ethoxybenzoyloxyethylene), poly (2-methoxybenzoyloxyethylene), poly (4-methoxybenzoyloxyethylene) ), Poly (4-phenylbenzoylo) Although it is possible to use various types of polyvinyl esters such as Shiechiren), to use from the viewpoint poly compatibility with the polylactic acid resin Among these (4-hydroxystyrene) (polyvinyl phenol) preferred.

  The polylactic acid-based resin laminated sheet of the present invention is a polyester having a glass transition temperature of 60 ° C. or less for the layer A and / or layer B constituting the polylactic acid-based resin laminated sheet from the viewpoint of imparting impact resistance and improving moldability. It is preferable to contain 0.1 to 40% by weight of the resin R based on the entire polylactic acid resin composition constituting the layer. More preferably, it is 0.2-30 weight%, Most preferably, it is 0.5-20 weight%. When the polyester resin R exceeds 40% by weight, heat resistance and transparency may be lowered, and when the polyester resin R is less than 0.1% by weight, the effect of improving impact resistance may be lowered. is there.

  Usually, the impact resistance and flexibility of a polymer are correlated with each other, and a glass transition point can be given as one guideline for evaluating the flexibility of a polymer. That is, in order to improve the impact resistance of the polylactic acid-based resin laminate sheet of the present invention, the polyester-based resin R has a glass transition temperature of 60 ° C. or less in consideration of the glass transition temperature of the polylactic acid-based resin. It is preferred to use some.

  The weight average molecular weight of the polyester-based resin R is not particularly limited, but there are preferable values for the lower limit and the upper limit, respectively, mainly from the viewpoint of maintaining heat resistance and compatibility with the polylactic acid resin. Is preferably 2,000 to 200,000, more preferably 5,000 to 100,000, and particularly preferably 10,000 to 80,000.

  Although there is no restriction | limiting in particular about the kind of this polyester-type resin R whose glass transition temperature is 60 degrees C or less, It is comprised by aromatic and / or aliphatic polyester, a polyester-type and / or polyether-type segment, and a polylactic acid segment. A resin composition is preferred.

  Specific examples of such aromatic and / or aliphatic polyesters include polybutylene terephthalate, polypropylene terephthalate, polybutylene sebacate, polybutylene succinate, polybutylene succinate / terephthalate, polybutylene adipate / terephthalate, polybutylene succinate / Adipate, polypropylene sebacate, polypropylene succinate, polypropylene succinate / terephthalate, polypropylene adipate / terephthalate, polypropylene succinate / adipate, and the like can be used. Among these, polybutylene adipate / terephthalate and polybutylene succinate / adipate are particularly effective for imparting impact resistance.

  The resin composition composed of a polyester-based and / or polyether-based segment and a polylactic acid segment is more preferably a block copolymer of a polyester-based and / or polyether-based resin and a polylactic acid resin. Moreover, it is preferable to have one or more polylactic acid segments having a molecular weight of 1,500 or more in one molecule of the block copolymer. In this case, the polylactic acid segment is incorporated into a crystal formed from a polylactic acid polymer as a base material, thereby causing an action of being tethered to the base material, and sufficient bleed out of the block copolymer is achieved. Can be suppressed.

  Specific examples of such polyethers include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and polyethylene glycol / polypropylene glycol copolymers.

  Specific examples of the polyester include polybutylene terephthalate, polypropylene terephthalate, polybutylene sebacate, polybutylene succinate, polybutylene succinate / terephthalate, polybutylene adipate / terephthalate, polybutylene adipate / succinate, polypropylene sebacate, polypropylene Succinate, polypropylene succinate / terephthalate, polypropylene adipate / terephthalate, polypropylene adipate / succinate and the like can be used.

  The polylactic acid-based resin laminate sheet of the present invention has at least one layer selected from the layer A and the layer B, that is, the layer A and the layer A in a form in which the polyester-based resin R having a glass transition temperature of 60 ° C. or less is dispersed. Although it is preferable that it is contained in one or both of the layers B, the dispersion diameter is preferably 0.1 μm or less, more preferably 0.05 μm or less, particularly preferably 0.01 μm or less. It may be contained in the sheet in the form. That is, when the dispersion diameter exceeds 0.1 μm, the transparency of the sheet may be deteriorated or the impact resistance improving effect may not appear.

  Next, the crystal nucleating agent will be described.

  In the resin composition constituting the polylactic acid-based resin laminated sheet of the present invention, a crystal nucleating agent is used to suppress and refine the excessive growth of crystals of the polylactic acid-based resin and to accelerate the crystallization speed. Is used. Such a crystal nucleating agent needs to have good compatibility with the polylactic acid-based resin, and it is necessary to increase the crystallization speed and maintain the transparency of the resin when crystallized. Examples of such crystal nucleating agents include aliphatic carboxylic acid amides, aliphatic carboxylates, aliphatic alcohols, aliphatic carboxylic acid esters, aliphatic / aromatic carboxylic acid hydrazides, melamine compounds, and phenylphosphonic acid metal salts. Can be used.

  Specific examples of such aliphatic carboxylic acid amides include aliphatic monoamides such as lauric acid amide, palmitic acid amide, oleic acid amide, stearic acid amide, erucic acid amide, behenic acid amide, ricinoleic acid amide and hydroxystearic acid amide. Carboxylic acid amides, N-oleyl palmitic acid amide, N-oleyl oleic acid amide, N-oleyl stearic acid amide, N-stearyl oleic acid amide, N-stearyl stearic acid amide, N-stearyl erucic acid amide, methylol stearic acid N-substituted aliphatic monocarboxylic amides such as amide, methylol behenic acid amide, methylene bis stearic acid amide, ethylene bis lauric acid amide, ethylene bis capric acid amide, ethylene bis oleic acid amide, ethylene vinyl Stearic acid amide, ethylene biserucic acid amide, ethylene bisbehenic acid amide, ethylene bisisostearic acid amide, ethylene bishydroxystearic acid amide, butylene bisstearic acid amide, hexamethylene bisoleic acid amide, hexamethylene bisstearic acid Aliphatic biscarboxylic amides such as amide, hexamethylene bisbehenic acid amide, hexamethylene bishydroxystearic acid amide, m-xylylene bisstearic acid amide, m-xylylene bis-12-hydroxystearic acid amide, N, N′-dioleyl sebacic acid amide, N, N′-dioleyl adipic acid amide, N, N′-distearyl adipic acid amide, N, N′-distearyl sebacic acid amide, N, N′-di Stearyl isophthalic acid N-substituted aliphatic carboxylic acid bisamides such as N, N'-distearyl terephthalamide, N-butyl-N'-stearyl urea, N-propyl-N'-stearyl urea, N-stearyl-N N-substituted ureas such as' -stearyl urea, N-phenyl-N'-stearyl urea, xylylene bisstearyl urea, toluylene bisstearyl urea, hexamethylene bisstearyl urea, diphenylmethane bisstearyl urea, diphenylmethane bislauryl urea Can be used. These may be one kind or a mixture of two or more kinds. Among these, aliphatic monocarboxylic acid amides, N-substituted aliphatic monocarboxylic acid amides, and aliphatic biscarboxylic acid amides are preferably used. In particular, palmitic acid amide, stearic acid amide, erucic acid amide, and behenine. Acid amide, ricinoleic acid amide, hydroxy stearic acid amide, N-oleyl palmitic acid amide, N-stearyl erucic acid amide, ethylene biscapric acid amide, ethylene bis oleic acid amide, ethylene bis lauric acid amide, ethylene bis erucic acid amide, m-Xylylene bis-stearic acid amide and m-xylylene bis-12-hydroxystearic acid amide are preferably used.

  Specific examples of such aliphatic carboxylates include sodium laurate, potassium laurate, potassium hydrogen laurate, magnesium laurate, calcium laurate, zinc laurate, silver laurate, and lithium myristate. , Sodium myristate, potassium hydrogen myristate, magnesium myristate, calcium myristate, zinc myristate, silver myristate, myristate, lithium palmitate, potassium palmitate, magnesium palmitate, calcium palmitate, zinc palmitate , Copper palmitate, lead palmitate, thallium palmitate, cobalt palmitate, etc., sodium oleate, potassium oleate, magnesium oleate, calcium oleate Oleate such as sodium oleate, zinc oleate, lead oleate, thallium oleate, copper oleate, nickel oleate, sodium stearate, lithium stearate, magnesium stearate, calcium stearate, barium stearate, aluminum stearate, Stearates such as thallium stearate, lead stearate, nickel stearate, beryllium stearate, sodium isostearate, potassium isostearate, magnesium isostearate, calcium isostearate, barium isostearate, aluminum isostearate, zinc isostearate, isostearate Isostearates such as nickel acid, sodium behenate, potassium behenate, magnesium behenate, behenic acid Lucium, barium behenate, aluminum behenate, zinc behenate, nickel behenate, etc., behenates, sodium montanate, potassium montanate, magnesium montanate, calcium montanate, barium montanate, aluminum montanate, montanic acid Montanates such as zinc and nickel montanate can be used. These may be one kind or a mixture of two or more kinds. Of these, stearic acid salts and montanic acid salts are preferably used. Specifically, sodium stearate, potassium stearate, zinc stearate, and calcium montanate are particularly preferably used.

  Specific examples of the aliphatic alcohol include aliphatic monoalcohols such as pentadecyl alcohol, cetyl alcohol, heptadecyl alcohol, stearyl alcohol, nonadecyl alcohol, eicosyl alcohol, seryl alcohol, and melyl alcohol, Aliphatic polyhydric alcohols such as 6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, cyclopentane-1,2-diol, Cyclic alcohols such as cyclohexane-1,2-diol and cyclohexane-1,4-diol can be used. These may be one kind or a mixture of two or more kinds. Among these, aliphatic monoalcohols are preferably used, and specifically, stearyl alcohol is particularly preferably used.

  Specific examples of the aliphatic carboxylic acid ester include lauric acid cetyl ester, lauric acid phenacyl ester, myristic acid cetyl ester, myristic acid phenacyl ester, palmitic acid isopropylidene ester, palmitic acid dodecyl ester, and palmitic acid tetraethyl ester. Aliphatic monocarboxylic acid esters such as dodecyl ester, palmitic acid pentadecyl ester, palmitic acid octadecyl ester, palmitic acid cetyl ester, palmitic acid phenyl ester, palmitic acid phenacyl ester, stearic acid cetyl ester, behenic acid ethyl ester, Monoesters of ethylene glycol such as glycol monolaurate, glycol monopalmitate, glycol monostearate, glycol dilaurate, di Diesters of ethylene glycol such as glycol lumitate and glycol distearate, glyceryl monoesters such as monolauric acid glycerin ester, monomyristic acid glycerin ester, monopalmitic acid glycerin ester, monostearic acid glycerin ester, dilauric acid glycerin ester, Glycerin diesters such as dimyristic acid glycerin ester, dipalmitic acid glycerin ester, distearic acid glycerin ester, trilauric acid glycerin ester, trimyristic acid glycerin ester, tripalmic acid glycerin ester, tristearic acid glycerin ester, palmitodiolein, Glycerin triesters such as palmitodistearin and oleodistearin can be usedThese may be one kind or a mixture of two or more kinds. Among these, ethylene glycol diesters are preferable, and ethylene glycol distearate is particularly preferably used.

  Specific examples of such aliphatic / aromatic carboxylic acid hydrazides include sebacic acid dibenzoic acid hydrazide, specific examples of melamine compounds, specific examples of melamine cyanurate, polymelate melamine, and phenylphosphonic acid metal salts. For example, phenylphosphonic acid zinc salt, phenylphosphonic acid calcium salt, phenylphosphonic acid magnesium salt, and phenylphosphonic acid magnesium salt can be used.

  The specific addition amount of these transparent nucleating agents is preferably 0.1 to 2.5% by weight, more preferably 0.3 to 2% by weight, based on the whole polylactic acid resin composition constituting the layer A. %, Particularly preferably 0.5 to 1.5% by weight. When the added amount is less than 0.1% by weight, the effect as a transparent nucleating agent becomes insufficient, and the heat resistance may be lowered. When the added amount is larger than 2.5% by weight, not only the transparency is lowered, but also the appearance and physical properties may be changed.

  By the way, the transparency of a sheet | seat is determined by the surface roughness of the both surfaces of a sheet | seat represented as surface haze, and the cloudiness degree by the light absorption and scattering inside a sheet | seat represented as an internal haze. The polylactic acid-based resin laminate sheet of the present invention needs to be composed of a layer A containing a crystal nucleating agent and a layer B containing substantially no crystal nucleating agent. The term “substantially free” as used herein means that a substance that exhibits an effect as a crystal nucleating agent is not contained. Layer A is crystallized by heat treatment and contributes to improving the heat resistance of the sheet, and layer B is not crystallized by heat treatment, so the sheet surface is kept smooth and contributes to reduction of surface haze. Further, since the sheet surface is the layer B that is not crystallized by heat treatment, the glossiness of the sheet is also improved.

  There is no restriction | limiting in particular in the structure of the polylactic acid-type resin laminated sheet of this invention, Layers other than this layer A and this layer B may be included, and it is a 2 layer structure, a 3 layer structure, or more multilayer structure. It does not matter. In particular, for the above reasons, either one of the outermost layers of the sheet is preferably layer B, more preferably both sides of the outermost layer of the sheet are layers B, layer A is an inner layer, and layer B is both outer layers. The three-layer structure is particularly preferable.

  In the polylactic acid-based resin laminated sheet of the present invention, the ratio of the thickness of the layer A to the total thickness of the laminated sheet is 50.1% to 99.9%, so that both heat resistance, transparency, and glossiness are compatible. Necessary from above. Preferably they are 60.1%-97%, More preferably, they are 70.1%-95%, More preferably, they are 80.1%-90%. That is, when the ratio of the thickness of the layer A is less than 50.1%, there are few crystallized portions of the sheet by heat treatment, and the heat resistance is insufficient. On the other hand, if the ratio of the thickness of the layer A exceeds 99.9%, the sheet surface cannot be kept smooth, so that the surface haze increases and the transparency deteriorates, and the glossiness also deteriorates.

  Various particles can be contained in the polylactic acid-based resin laminated sheet of the present invention. The average particle diameter of such particles is preferably 0.01 to 10 μm, more preferably 0.02 to 5 μm, and still more preferably 0.03 to 2 μm. The content of the particles is preferably 0.01 to 10 parts by weight, more preferably 0.02 to 5 parts by weight, and further preferably 0.03 to 3 parts by weight with respect to 100 parts by weight of the polylactic acid resin. It is. That is, if the average particle diameter is less than 0.01 μm, or the content is less than 0.01 parts by weight, the slip between the molding die and the film becomes worse, molding unevenness occurs, the film breaks, In addition, moldability may be poor, such as poor mold releasability from the mold. On the other hand, if the average particle diameter is larger than 10 μm or the content is more than 10 parts by mass, the transparency of the film may be lowered.

  The type of such particles is not particularly limited as long as it is appropriately selected according to the purpose and application, such as further improvement of the crystallization speed and improvement of slipperiness with a molding die, Examples thereof include inorganic particles, organic particles, crosslinked polymer particles, and internal particles generated in the polymerization system. Of course, these particles may be used alone or in combination. When mixed and used, each type of particle may be in the range of the average particle diameter, and the total content of all types of particles may be in the range. .

  A specific example of such particles will be described. That is, the inorganic particles are not particularly limited, but include silicon oxide such as silica, various carbonates such as calcium carbonate, magnesium carbonate, and barium carbonate, various sulfates such as calcium sulfate and barium sulfate, and various types such as kaolin and talc. Viscosity of composite oxides, various phosphates such as lithium phosphate, calcium phosphate and magnesium phosphate, various oxides such as aluminum oxide, titanium oxide and zirconium oxide, various salts such as lithium fluoride, and montmorillonite Minerals can be used.

  As the organic particles, fine particles made of calcium oxalate, terephthalate such as calcium, barium, zinc, manganese, magnesium and the like are used. Examples of the crosslinked polymer particles include fine particles made of a vinyl monomer such as divinylbenzene, styrene, acrylic acid, and methacrylic acid, or a copolymer. In addition, organic fine particles such as polytetrafluoroethylene, benzoguanamine resin, thermosetting epoxy resin, unsaturated polyester resin, thermosetting urea resin, and thermosetting phenol resin are also preferably used.

  Finally, as the internal particles generated in the polymerization system, for example, particles generated by a known method in which an alkali metal compound, an alkaline earth metal compound or the like is added to the reaction system and a phosphorus compound is further added are used. can do.

  Although the thickness of the whole polylactic acid-type resin laminated sheet of this invention is not specifically limited, Preferably it is 50-2000 micrometers, More preferably, it is 100-1500 micrometers, More preferably, it is 200-1000 micrometers. That is, when the sheet thickness is less than 50 μm, sheet tearing is likely to occur at the time of molding, and not only the moldability is deteriorated, but also the problem that the strength of the molded body is weakened even when it can be molded is likely to occur. Become. Further, when the sheet thickness is larger than 2000 μm, heating before molding is required for a long time, and even if it can be successfully molded, a problem that it is likely to become brittle tends to occur.

  In addition, the polylactic acid-based resin laminated sheet of the present invention has additives as necessary, for example, flame retardants, heat stabilizers, impact resistance improvers, light stabilizers, as long as the effects of the present invention are not impaired. , Antioxidants, anti-coloring agents, UV absorbers, antistatic agents, mold release agents, plasticizers, tackifiers, organic lubricants such as fatty acid esters and waxes, antifoaming agents such as polysiloxanes, pigments or dyes, etc. An appropriate amount of a functional agent such as a colorant can be added.

  It is also effective to form a functional layer by applying a coating liquid containing the functional drug on the surface for the purpose of blocking prevention, antistatic, imparting releasability, improving scratch resistance, etc. For the formation of the layer, an in-line coating method performed in the sheet manufacturing process or an off-line coating method performed after winding the sheet can be used.

  The specific method of coating for forming such a functional layer is not particularly limited, but wire bar coating method, doctor blade method, micro gravure coating method, gravure roll coating method, reverse roll coating method, air knife coating method, A rod coating method, a die coating method, a kiss coating method, a reverse kiss coating method, an impregnation method, a curtain coating method, a spray coating method, an air doctor coating method, or a coating apparatus other than these can be applied alone or in combination.

  Further, as another method for forming such a functional layer, means for applying a coating solution containing the functional agent in the stretching step can be employed. In such means, the coating solution is applied to an unstretched sheet and biaxially stretched sequentially or simultaneously, the coating solution is applied to a uniaxially stretched film, and further stretched in a direction perpendicular to the previous uniaxial stretching direction. There is a method, or a method of further stretching after coating the coating solution on a biaxially stretched film.

  In addition, in order to improve the applicability | paintability to the sheet | seat of this coating liquid and adhesiveness, a chemical process and an electrical discharge process can be given to a sheet | seat before application | coating.

  In particular, in the present invention, it is preferable to have a release layer on at least one surface of the polylactic acid-based resin laminated sheet. As will be described later, the polylactic acid-based resin laminated sheet of the present invention is often crystallized by heat treatment in a molding die to exhibit heat resistance, and in that case, the mold is released between the sheet and the die. This is to improve the property.

  As the material of the release layer, known materials can be used, which are selected from long-chain alkyl acrylate, silicone resin, melamine resin, fluororesin, cellulose derivative, urea resin, polyolefin resin, paraffin release agent, and the like. One or more are preferably used.

  The long-chain alkyl acrylate used for the release layer of the polylactic acid-based resin laminate sheet of the present invention can be copolymerized with an acrylic monomer having an alkyl group having 12 to 25 carbon atoms in the side chain, and this acrylic monomer. A copolymerized acrylic resin with a monomer, and the copolymerization ratio of an alkyl acrylate monomer having an alkyl group having 12 to 25 carbon atoms in the side chain in the copolymerized acrylic resin is 35% by mass or more. The copolymerization amount is preferably 35 to 85% by mass, and more preferably 60 to 80% by mass in terms of blocking resistance and copolymerization.

  Such an alkyl acrylate monomer is not particularly limited as long as it satisfies the above requirements. For example, dodecyl acrylate, tridecyl acrylate, tetradecyl acrylate, pentadecyl acrylate, hexadecyl acrylate, acrylic Long chains such as heptadecyl acrylate, octadecyl acrylate, nonadecyl acrylate, eicosyl acrylate, henecosyl acrylate, docosyl acrylate, tricosyl acrylate, tetracosyl acrylate, pentacosyl acrylate, dodecyl methacrylate, eicosyl methacrylate, pentacosyl methacrylate An alkyl group-containing acrylic monomer can be used.

  When such a long-chain alkyl acrylate is used as a release layer, it is particularly preferable to use a water-based coating agent from the viewpoint of the environment. For example, in order to form an emulsion, other copolymerizable monomers include: The acrylic monomer can be used. Monomers include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethoxyethyl acrylate, 2-methoxyethyl acrylate, 2-butoxyethyl acrylate, methyl methacrylate, ethyl methacrylate, acrylonitrile, methacrylonitrile. , Vinyl acetate, (meth) acrylic acid, styrene, itaconic acid, (meth) acrylamide, 2-hydroxyethyl (meth) acrylate, diethylene glycol mono (meth) acrylate, N-methylol (meth) acrylamide, dimethylaminoethyl (meth) Acrylate, diethylaminoethyl (meth) acrylate, (meth) acryloyloxyethyl phosphate ester, sodium vinyl sulfonate, sodium styrene sulfonate, maleic anhydride and the like can be used.

  Although it does not specifically limit as a silicone resin used for the mold release layer of the polylactic acid-type resin laminated sheet of this invention, It is preferable to use an emulsion type thing from the surface of a dispersibility and stability. Specifically, Silicone KM-786, KM-787, KM-788, KM-9736, KM-9737, KM-9738, KM-9744, KM-9745, KM-9746, etc. manufactured by Shin-Etsu Chemical Co., Ltd. Can be used.

  Further, curable silicones can also be preferably used, for example, those of addition reaction systems such as solvent addition type and solventless addition type, those of condensation reaction systems such as solvent condensation type and solventless condensation type, solvent ultraviolet curing type Active energy ray-curable materials such as a solventless ultraviolet curable type and a solventless electron beam curable type can be used, and these can be used alone or in combination of two or more.

  The release layer of the polylactic acid-based resin laminate sheet of the present invention preferably has a dry laminate thickness of 0.005 to 10 μm, particularly preferably 0.01 to 1 μm. Although it depends on the thickness of the entire sheet, when the dry lamination thickness of the release layer is less than 0.005 μm, it is difficult to obtain a uniform coating layer, and thus uneven coating tends to occur on the product, resulting in the desired release performance. Inferior. When the dry lamination thickness of the release layer exceeds 10 μm, the polylactic acid-based resin lamination sheet becomes difficult to reuse as polyester, and the recoverability deteriorates, which is not preferable.

  In particular, in the present invention, it is preferable to have an antistatic layer on at least one side of the polylactic acid-based resin laminated sheet.

  As the material for the antistatic layer, known materials can be used, but an antistatic agent having a quaternary ammonium salt in the main chain is preferred. Antistatic properties can be imparted by adding a copolymer containing at least one of sulfonic acid, sulfonate, vinyl imidazolium salt, dianyl ammonium chloride, dimethyl ammonium chloride, and alkyl ether sulfate. .

  The coating solution containing the antistatic resin used in the antistatic layer is made of methylol or alkylol as a cross-linking agent for improving the adhesion (blocking), water resistance, solvent resistance and mechanical strength of the coating layer. Urea-based, melamine-based, guanamine-based, acrylic-based, acrylamide-based, polyamide-based, polyurethane-based, polyester-based compounds, epoxy compounds, aziridine compounds, oxazoline compounds, carbodiimide compounds, block polyisocyanates, silane coupling agents, It may contain a titanium coupling agent, a zirco aluminate coupling agent, heat, peroxide, a photoreactive vinyl compound, a photosensitive resin, or the like.

  In addition, silica, silica sol, alumina, alumina sol, zirconium sol, kaolin, talc, calcium carbonate, titanium oxide, barium salt, carbon black, molybdenum sulfide, antimony oxide sol, etc. are used as inorganic fine particles to improve adhesion and slipperiness. It may contain, and if necessary, antifoaming agent, coatability improver, thickener, organic lubricant, organic polymer particles, antioxidant, UV absorber, foaming agent, dye, etc. You may contain.

  Further, the coating solution may contain a polymer other than the resin in the present invention for improving the properties of the coating solution or the coating layer.

  The antistatic layer of the polylactic acid-based resin laminate sheet of the present invention preferably has a dry laminate thickness of 0.005 to 10 μm, particularly preferably 0.01 to 1 μm. When the dry lamination thickness is less than 0.005 μm, it is difficult to obtain a uniform coating layer, and thus uneven coating tends to occur on the product, and as a result, the intended antistatic performance is poor. Moreover, when larger than 10 micrometers, it is inferior to transparency.

The polylactic acid-based resin laminated sheet of the present invention has a carboxyl group terminal concentration of 30 equivalents / percent from the viewpoint of suppressing strength reduction due to decomposition of the sheet and a molded product obtained using the sheet and improving heat resistance. It is preferably 10 ³ kg or less, more preferably 20 equivalents / 10 ³ kg or less, and particularly preferably 10 equivalents / 10 ³ kg or less. When the carboxyl group terminal concentration in the polylactic acid-based resin exceeds 30 equivalents / 10 ³ kg, hydrolysis is caused when the laminated sheet and molded body are used under high temperature and high humidity conditions or contact conditions with hot water. As a result, the strength decreases, and a molded body such as a container becomes brittle and may be easily broken.

Examples of a method for setting the carboxyl group terminal concentration of the laminated sheet to 30 equivalents / 10 ³ kg or less include, for example, a method of controlling by a catalyst and a thermal history at the time of synthesizing a polylactic acid-based resin, and a reduction in extrusion temperature at the time of forming a sheet. Or the method of reducing thermal history, such as shortening residence time, the method of blocking a carboxyl group terminal using a reactive compound, etc. are mentioned.

  In the method of blocking the carboxyl group terminal using a reactive compound, it is preferable that at least a part of the carboxyl group terminal in the sheet is blocked, and it is more preferable that the whole amount is blocked. Examples of reactive compounds include condensation reactive compounds such as aliphatic alcohols and amide compounds, and addition reactive compounds such as carbodiimide compounds, epoxy compounds, and oxazoline compounds, but extra by-products are generated during the reaction. Addition reaction type compounds are preferred because of their difficulty.

  In the polylactic acid-based resin laminated sheet of the present invention, the amount of lactic acid oligomer component contained in the laminated sheet is preferably 0.5% by mass or less. More preferably, it is 0.4 mass% or less, More preferably, it is 0.3 mass% or less. When the amount of lactide contained in the laminated sheet exceeds 0.5% by mass, handling properties and transparency deteriorate when the lactic acid oligomer component remaining in the laminated sheet is precipitated as a powder or liquid. There is a case. In addition, the hydrolysis of the polylactic acid resin may proceed, and the aging resistance of the sheet may deteriorate. The term “lactic acid oligomer component” as used herein refers to lactic acid, a linear oligomer of lactic acid, a cyclic oligomer of lactic acid which is quantitatively representative among lactic acid, a cyclic oligomer of lactic acid, and the like. Lactide and DD-lactide, DL (meso) -lactide.

  The polylactic acid-based resin laminate sheet of the present invention may be a stretched sheet mainly from the viewpoint of aging resistance and dimensional stability, and in that case, a biaxially stretched sheet is preferable. When obtaining a stretched sheet, it can be performed by existing stretched sheet manufacturing methods such as the inflation method, simultaneous biaxial stretching method, and sequential biaxial stretching method, but the orientation state of the sheet that achieves both formability and heat resistance is controlled. The sequential biaxial stretching method is preferable because it can be easily performed and the film forming speed can be increased.

  Next, the method for producing the polylactic acid-based resin laminated sheet of the present invention will be specifically described.

  That is, the polymer mainly composed of polylactic acid in the present invention can be obtained by the following method. As a raw material, a lactic acid component of L-lactic acid or D-lactic acid is mainly used, and a hydroxycarboxylic acid other than the lactic acid component described above can be used in combination. Further, a cyclic ester intermediate of hydroxycarboxylic acid, for example, lactide, glycolide, etc. can be used as a raw material. Furthermore, the dicarboxylic acids and glycols mentioned above can also be used.

  A polymer mainly composed of polylactic acid can be obtained by a method of directly dehydrating and condensing the raw materials or a method of ring-opening polymerization of the cyclic ester intermediate. For example, in the case of producing by direct dehydration condensation, lactic acid or lactic acid and hydroxycarboxylic acid are preferably subjected to azeotropic dehydration condensation in the presence of an organic solvent, particularly a phenyl ether solvent, and particularly preferably a solvent distilled by azeotropic distillation. A polymer having a high molecular weight can be obtained by polymerizing by a method in which water is removed from the solvent and the solvent is brought into a substantially anhydrous state and returned to the reaction system.

  It is also known that a high molecular weight polymer can be obtained by subjecting a cyclic ester intermediate such as lactide to ring-opening polymerization using a catalyst such as tin octylate. At this time, when using an organic solvent, a method for adjusting the conditions for removing moisture and low molecular weight compounds during heating and reflux, a method for suppressing the depolymerization reaction by deactivating the catalyst after the completion of the polymerization reaction, and heat treating the produced polymer By using such a method, a polymer having a small amount of lactide can be obtained.

  Below, when obtaining the unstretched polylactic acid-type laminated sheet of this invention, Furthermore, the preferable film forming method in the case of performing a tenter type | formula sequential biaxial stretching is demonstrated.

  First, after drying a resin composed of polylactic acid at 100 to 150 ° C. for 3 hours or more under a reduced pressure of 5 torr, the resin for the A layer and the resin for the B layer are supplied to separate independent extruders, and depending on the melt viscosity A wire electrode having a diameter of 0.5 mm is formed on a metal cooling casting drum from a slit-shaped die having a lip interval of 2 to 3 mm by, for example, a T-die method. Is used to apply a static electricity to bring it into close contact to obtain a non-oriented cast sheet.

  A preferable range of the surface temperature of the metallic cooling casting drum is 0 to 30 ° C, a more preferable range is 3 to 25 ° C, and a particularly preferable range is 5 to 20 ° C. By setting the surface temperature of the metal cooling casting drum within this range, good transparency can be exhibited.

  When obtaining a stretched sheet, the unstretched cast sheet thus obtained is heated to a temperature at which longitudinal stretching is performed by conveying it onto a heated roll. For such temperature increase, auxiliary heating means such as an infrared heater may be used in combination. A preferable range of the stretching temperature is 80 to 95 ° C, more preferably 85 to 90 ° C. The unoriented non-stretched sheet thus heated is stretched in one or two or more stages in the longitudinal direction of the sheet using the difference in peripheral speed between the heated rolls. The total draw ratio is preferably 1.2 to 3.5 times, more preferably 1.5 to 3.0 times.

  After the sheet uniaxially stretched in this way is cooled once, the both ends of the sheet are held with clips and guided to a tenter, and stretched in the width direction. The stretching temperature is preferably 75 to 90 ° C, more preferably 80 to 85 ° C. The draw ratio is preferably 1.2 to 3.5 times, more preferably 1.5 to 3.0 times.

  In order to reduce the difference in performance in the width direction of the sheet, it is preferable to perform stretching in the width direction at a temperature lower by 1 to 15 ° C. than the stretching temperature in the longitudinal direction.

  Further, if necessary, re-longitudinal stretching and / or re-lateral stretching may be performed.

  Next, this stretched sheet is heat-set under tension or while relaxing in the width direction. From the viewpoint of mainly imparting thermal dimensional stability to the sheet, and simultaneously reducing the amount of lactide by scattering the lactide contained in the sheet, the preferred heat treatment temperature is 100 to 160 ° C., more preferably 120 to 150. ° C. The heat treatment time is preferably in the range of 0.2 to 30 seconds, but is not particularly limited. The relaxation rate is preferably 1 to 8%, more preferably 2 to 5%, from the viewpoint of reducing the thermal contraction rate in the width direction. More preferably, the sheet is once cooled before the heat setting treatment.

  Further, the sheet is cooled and rolled up to room temperature, if necessary, while being subjected to relaxation treatment in the longitudinal and width directions, to obtain a target polylactic acid-based resin laminated sheet.

  Next, a method for obtaining a molded article having both heat resistance, transparency and glossiness, which is an object of the present invention, will be described.

  In the present invention, a molded product having both heat resistance, transparency and gloss can be obtained by crystallizing the polylactic acid-based resin laminated sheet described above at the time of molding or after molding. As a molding method, various molding methods such as vacuum molding, vacuum pressure molding, plug assist molding, straight molding, free drawing molding, plug and ring molding, skeleton molding, and the like can be applied. However, it is necessary to crystallize the molded body by some method (for example, heat treatment) at the time of molding or after molding. Specific examples of crystallizing the polylactic acid resin laminated sheet at the time of molding or after molding include, for example, a method of crystallizing as it is in a mold at the time of molding (hereinafter referred to as in-mold crystallization method), Examples thereof include a method of heat-treating an amorphous molded body (hereinafter referred to as a post-crystallization method). In the in-mold crystallization method and the post-crystallization method, optimum temperature conditions for crystallization of the molded product are different.

  In the case of the in-mold crystallization method, the set temperature condition of the mold is preferably the temperature range from the crystallization start temperature at the time of temperature drop to the crystallization end temperature in the differential scanning calorimetry of the sheet, and the peak of the crystallization peak A temperature in the vicinity is more preferred. If the temperature is higher than the crystallization start temperature, the crystallization speed is remarkably reduced, the productivity and operability are deteriorated, and further, crystallization may not occur, and the target molded product may not be obtained. At a temperature lower than the end temperature, the crystallization rate is remarkably small, and the desired molded article may not be obtained. In this method, the holding time in the mold varies depending on the type of the sheet, but there is no particular limitation as long as it is longer than the time required for the molded body to sufficiently crystallize in the mold.

  On the other hand, in the case of the post-crystallization method, the set temperature condition of the mold is the temperature range from the glass transition point (Tg) to the melting point (Tm) of the sheet, more preferably (Tg + 5) ° C. to (Tm-20) ° C. Particularly preferred is a temperature range from (Tg + 10) ° C. to (Tm−40) ° C. When the set temperature is higher than Tm, transparency may be impaired or the shape may be distorted even if crystallization is performed in a short time, and further melting may occur when heated for a long time. On the other hand, at a temperature lower than Tg, the crystallization rate is remarkably small, and the target crystalline molded article may not be obtained. In this method, the time for heat-treating the molded product varies depending on the type of the sheet, but is not particularly limited as long as it is sufficient for the molded product to be sufficiently crystallized.

  Molded bodies obtained by thermoforming the polylactic acid-based resin laminate sheet as used in the present invention are various containers such as cups, trays and bottles obtained by publicly known and publicly used molding methods, films, sheets, bags, tubes, threads, etc. There are no restrictions on the shape, size, thickness, design, etc.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited thereto.

[Measurement and evaluation method]
Measurements and evaluations shown in the examples were performed under the following conditions.

(1) Surface specific resistance After being allowed to stand for 24 hours in a normal state (25 ° C., relative humidity 65%), measurement was performed at an applied voltage of 100 V using a digital ultrahigh resistance / microammeter (R8340A manufactured by Advantest) in that atmosphere. . The unit is Ω / □.

(2) Formability (Releasability)
A general vacuum pressure forming machine equipped with a cup-shaped mold having a diameter of 80 mm, a bottom diameter of 50 mm, and a height of 40 mm, for a single-wafer sample of a polylactic acid resin laminated sheet having a width of 460 mm, a length of 630 mm, and a thickness of 0.5 mm Thus, the sheet temperature was softened so as to be 90 ° C., and the die temperature was set to 110 ° C. and vacuum-pressed for 1 minute. Then, it evaluated on the following references | standards with the shape of the cup obtained by releasing from a metal mold | die.
○: Cup shape as mold △: Partial deformation (functions as a cup)
X: Large deformation (does not function as a cup).

(3) Heat resistance of molded body Using the cup molded in (1), the deformation of the cup was visually evaluated when placed in a constant temperature bath at 70 ° C for 2 hours.
○: No deformation Δ: Small deformation ×: Large deformation

(4) Transparency of molded body The haze value of the bottom surface portion of the cup molded in (1) was measured using a haze meter HGM-2DP type (manufactured by Suga Test Instruments Co., Ltd.). The measurement was performed 5 times per level, and the evaluation was performed according to the following criteria using the average value of the 5 measurements.
◯: Haze is less than 5% Δ: Haze is 5% or more and less than 10% ×: Haze is 10% or more.

(5) Gloss of molded product The 60-degree specular gloss of the bottom part of the cup molded in (1) was measured based on JIS-Z8741 and evaluated based on the following criteria using an average value of 5 points. .
○: Glossiness is 100% or more. Δ: Glossiness is 60% or more and less than 100%. X: Glossiness is less than 60%.

(6) Lamination Thickness Ratio Using a transmission electron microscope (H-7100FA type manufactured by Hitachi), a sheet cross section at an accelerating voltage of 100 kV by an ultrathin section method (stained with RuO _{4 as} necessary) at a magnification of 10,000 to 100,000 Observation was performed twice, the interface was captured, the thickness of each layer was determined, and the thickness ratio was determined.

(7) Determination of Crystal Nucleating Agent Containment in Each Layer The presence or absence of the crystal nucleating agent contained in each layer was determined from the electron micrograph of the sheet cross section created and observed in (6).

[Polylactic acid resin P]
It shows about the polylactic acid resin used in the Example.
P-1:
Polylactic acid resin P-2 having a D-form content ratio of 1 mol% and a mass average molecular weight of 180,000 in terms of PMMA:
A polylactic acid resin having a D-form content ratio of 5 mol% and a mass average molecular weight of 180,000 in terms of PMMA.

[Crystal nucleating agent Q]
The crystal nucleating agent Q used in the examples will be described.
Q-1:
Ethylene bis lauric acid amide Q-2:
Ethylenebiserucamide Q-3:
Sodium stearate.

[Polyester resin R]
It shows about the polyester-type resin R used in the Example.
R-1:
Polybutylene succinate / adipate (Ile Chemical's Enpol (registered trademark) G4460, Tg ≦ 60 ° C.)
R-2:
Block copolymer of polylactic acid and poly (propylene sebacate) (Plamate (registered trademark) PD-150 manufactured by Dainippon Ink, Tg ≦ 60 ° C.)
R-3:
0.05 parts by weight of tin octylate is mixed with 70 parts by weight of polyethylene glycol having a weight average molecular weight of 12,000 and 30 parts by weight of L-lactide, and the mixture is stirred at 150 ° C. for 2 hours in a nitrogen atmosphere in a reaction vessel equipped with a stirring device. Polymerization was carried out to obtain a block copolymer R-3 of polyethylene glycol and polylactic acid having a polylactic acid segment having a weight average molecular weight of 2,500 (Tg ≦ 60 ° C.).

[Create release agent]
Silicone KM-787 manufactured by Shin-Etsu Chemical Co., Ltd. was diluted 36 times with pure water.

[Preparation of antistatic agent]
As an acrylic resin, a copolymer (aqueous emulsion) polymerized from an acrylic acid alkyl ester and a methacrylic acid alkyl ester (composition ratio 50:50) having a glass transition point of about 40 ° C. and a particle size of about 50 nm, polyester Polyester copolymer polymerized from an acid component (terephthalic acid, 5-sodium isophthalic acid 90:10) and a diol component (ethylene glycol, diethylene glycol 95: 5) at a secondary transition point of about 80 ° C. As a coalescence and antistatic agent, ammonium salt of polystyrene sulfonic acid (molecular weight 10,000), colloidal silica having a particle size of 140 nm, and organic particles, methyl methacrylate and ethylene glycol bismethacrylate having a particle size of about 5 μm (composition ratio 50: 50) as a copolymer or surfactant Using a mixture of aliphatic fluorosurfactant, ethylene glycol monotertiary butyl ether and water in a ratio of 10:60:30, acrylic resin / antistatic agent / polyester resin / colloidal silica / organic particles / surfactant An aqueous dispersion having a solid content concentration of 4.5% was prepared at a ratio of agent = 50/25/25 / 0.3 / 0.5 / 0.03.

[Creation of crystal nucleator master pellet]
P-1 / Q-1:
97 parts by weight of polylactic acid (P-1) and 3 parts by weight of ethylenebislauric acid amide (Q-1) were supplied to a vent type twin screw extruder and kneaded at 200 ° C. to obtain master pellets.
Other master pellets were similarly prepared by changing the type of polylactic acid resin and the type of crystal nucleating agent.

[Preparation of polylactic acid resin laminate sheet]
Example 1
Using polylactic acid (P-1), master pellet (P-1 / Q-1) and polyester resin (R-1) as layer A, P-1: Q-1: R-1 = 98: 1 Mixed raw material adjusted to be 1 wt%, using polylactic acid (P-1) and polyester resin (R-1) as layer B, so that P-1: R-1 = 99: 1 wt% The prepared mixed raw materials were supplied to separate independent bent twin-screw extruders, co-extruded from a T-die having a die temperature of 200 ° C., and cast on a casting drum cooled to 10 ° C. to obtain an unstretched sheet. Both surfaces of this sheet are subjected to corona discharge treatment in an air atmosphere, a release agent is applied to the surface in contact with the casting drum (surface D), and an antistatic agent is applied to the surface opposite to surface D (ND surface). And a coating layer having a dry lamination thickness of 0.17 μm on the D surface side and a dry lamination thickness of 0.17 μm on the ND surface side was formed on both surfaces. Layer B: Layer A: Layer B was 0.5: A sheet having a thickness of 9: 0.5 and a thickness of 0.5 mm was produced.

(Example 2 , 3, 5-14 , Comparative Examples 1-4 )
Example 1 except that the polylactic acid-based resin P, crystal nucleating agent Q, polyester-based resin R, layer structure, thickness ratio, release agent coating, and antistatic agent coating constituting each layer were changed as shown in Tables 1 to 3 It carried out like.

In Tables 1-3 above,
D: Coating the sheet surface in contact with the casting drum ND: Coating the sheet surface not in contact with the casting drum

  The polylactic acid-based resin laminated sheets of the examples all had good moldability, and the molded products obtained from the sheets had good heat resistance, transparency, and glossiness.

  On the other hand, in the comparative example, the layer A does not contain a crystal nucleating agent at all, that is, in the case of a polylactic acid resin single layer, although the transparency and gloss of the molded product are good, the microcrystallization at the time of molding does not occur. Since it did not occur, the heat resistance of the molded product was inferior (Comparative Example 1). Further, there is no layer B substantially containing no crystal nucleating agent, that is, in the case of a polylactic acid-based resin layer A single layer that uses a crystal nucleating agent, the heat resistance is good, but the sheet surface by heating at the time of molding The effect of the crystallization was great, and the transparency and gloss were significantly deteriorated (Comparative Example 2). Further, when the thickness ratio of the layer A is 50%, the transparency and glossiness are good, but the layer ratio in which fine crystallization occurs at the time of molding is insufficient, resulting in a sheet having poor heat resistance (Comparative Example 3). ).

  The polylactic acid resin laminated sheet of the present invention is a blister pack used for display and packaging of products, containers for beverage vending machine display bottles, lunch boxes, beverage cups, and other various packaging materials. Although it can apply to various industrial materials, such as a molded object and a surface material, the application range is not restricted to these.

  In particular, the polylactic acid-based resin laminate sheet of the present invention can be applied to various molding methods such as vacuum molding, vacuum pressure molding, plug assist molding, straight molding, free drawing molding, plug and ring molding, skeleton molding, etc., and has high moldability. Have. Moreover, it can use preferably for packaging materials, such as various shape-holding tools and containers in which transparency, glossiness, and heat resistance are requested | required.

Claims (5)

A laminated sheet comprising a polylactic acid resin composition,
The laminated sheet is composed of a layer A containing a crystal nucleating agent and a layer B substantially containing no crystal nucleating agent,
It is a three-layer structure in which layer A is an inner layer and layer B is both outer layers,
The ratio of the thickness of the layer A to the total thickness of the laminated sheet is 80.1 % to 99.9%. Further, the laminated sheet has a configuration in which the outermost layer of the laminated sheet is a layer B on both sides. Has a laminated structure,
The crystal nucleating agent is selected from aliphatic carboxylic acid amides, aliphatic carboxylates, aliphatic alcohols, aliphatic carboxylic acid esters, aliphatic / aromatic carboxylic acid hydrazides, melamine compounds, and phenylphosphonic acid metal salts. At least one,
A polylactic acid-based resin laminate sheet comprising 95 mol% or more of L-form or 95 mol% or more of D-form in the total lactic acid component of the polylactic acid-based resin. The polylactic acid-based resin laminate sheet according to claim 1 , further comprising a release layer on at least one surface of the polylactic acid-based resin laminate sheet. The polylactic acid-based resin laminate sheet according to claim 1 or 2 , further comprising an antistatic layer on at least one surface of the polylactic acid-based resin laminate sheet. At least one layer selected from the layer A and the layer B constituting the polylactic acid-based resin laminated sheet comprises a polyester resin R having a glass transition temperature of 60 ° C. or less with respect to the entire polylactic acid-based resin composition. The polylactic acid-based resin laminate sheet according to claim 1 , wherein the polylactic acid-based resin laminate sheet is contained in an amount of 0.1 to 40% by weight. The molded object comprised by the polylactic acid-type resin laminated sheet in any one of Claims 1-4 .