JP2005280361A - Production method of molded product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biodegradable composite sheet which has sufficient heat resistance and impact resistance and has good moldability and mold-release characteristics. <P>SOLUTION: This biodegradable composite sheet is formed from a layered product having at least three layers. The two outer layers of the above layered product consist of a mixture containing a polylactic acid-base polymer and a crystal nucleating agent, and at least one layer of inner layers inserted between the two outer layers of the above layered product consists of a mixture containing a biodegradable aliphatic-base polyester (except aliphatic aromatic polyester) excepting polylactic acid-base polymer, and crystal nucleating agent. In addition, a molded product is produced and obtained by the method of vacuum forming or pressure forming by using the biodegradable composite sheet. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a biodegradable composite sheet that can be decomposed in a natural environment and a molded body using the same.

  Containers such as trays and containers for various foods, and blister processed products used for display and packaging of various products, after obtaining a resin sheet, the sheet is formed by vacuum forming or pressure forming, which is a thermoforming method. Many of them are produced by molding. Conventionally, polyvinyl chloride resins, polyethylene terephthalate resins, polystyrene resins, polypropylene resins and the like have been used as resin sheets for obtaining these trays and containers.

  However, since the above sheet is chemically and biologically stable, it remains and accumulates with almost no decomposition even when left in a natural environment. These are not only scattered in the natural environment and contaminating the living environment of animals and plants, but also remain buried in garbage as they are hardly decomposed, thereby shortening the life of the landfill.

  On the other hand, a material composed of a biodegradable polymer that does not cause these problems is required, and many researches and developments have been conducted. One of them is polylactic acid. When a container is molded using a sheet using this polylactic acid, it is decomposed in the environment, so that it can be prevented from being scattered in the natural environment and contaminating the living environment of animals and plants. However, although this sheet made of polylactic acid is rich in moldability, it generally has insufficient heat resistance and impact resistance, and therefore has a problem in durability when formed into a container.

  As a method for increasing the heat resistance of polylactic acid, a molding die heated to 85 to 120 ° C. is used, and gold is molded while molding a resin containing polylactic acid and a crystal nucleating agent for promoting crystallization of polylactic acid. There is a method of promoting crystallization in a mold. For example, in Japanese Patent Application Laid-Open No. 8-193165, heat resistance and impact resistance are improved by using polylactocapton (dispersant of nucleating agent and impact resistance improving agent) and talc (crystal nucleating agent) in polylactic acid. In addition, in Japanese Patent Application Laid-Open No. 11-116784, diisodecyl adipate (crystallization accelerator and impact modifier) is added to polylactic acid to improve heat resistance and impact resistance. Improved shaped bodies are known. Furthermore, a molded body in which animal and vegetable oils are added to polylactic acid to improve heat resistance and impact resistance is also known.

  However, specific examples of these publications mainly relate to injection-molded articles, and there is also a description of part of extrusion molding, but examples of molding this extruded sheet are not described. The inventors prepared a sheet using polycaprolactone and talc for the above polylactic acid, and proceeded with crystallization of polylactic acid while forming this sheet with a molding die heated to 110 ° C. Although the melting point of polycaprolactone is about 60 ° C. and melts in the mold at 110 ° C., the molded body sticks to the mold when the molded body is taken out from the mold, and the molded body The molded body may be deformed and a desired shape cannot be obtained.

  In addition, the inventors have tried the same for a sheet obtained by adding diisodecyl adipate to polylactic acid and a sheet obtained by adding animal and vegetable oil to polylactic acid, but since diisodecyl adipate and animal and vegetable oil are used, When removing from the mold, deformation due to adhesion or stickiness may occur.

  Therefore, an object of the present invention is to obtain a biodegradable composite sheet having sufficient heat resistance and impact resistance and having good moldability and mold releasability.

  This invention is a biodegradable composite sheet formed from a laminate having at least two layers, wherein one layer of the laminate is composed of a mixture containing a polylactic acid polymer and a crystal nucleating agent, By using the biodegradable composite sheet characterized in that the other layer of the laminate is composed of a mixture containing a biodegradable aliphatic polyester excluding a polylactic acid polymer and a crystal nucleating agent, The above problem has been solved.

Moreover, it is preferable that the mixture which comprises said other layer contains a polylactic acid-type polymer.
Further, the laminate has at least three layers, the one layer forms both outer layers of the laminate, and the other layer is at least one of inner layers sandwiched between the outer layers of the laminate. Is preferably formed.

Furthermore, the composition ratio of the crystal nucleating agent with respect to 100 parts by weight of the polylactic acid polymer contained in the one layer is 0.5 to 50 parts by weight, and the polylactic acid based on 100 parts by weight of the whole laminate. The composition ratio of the biodegradable aliphatic polyester excluding the polymer is preferably 3 to 80 parts by weight.
The biodegradable aliphatic polyester preferably has a glass transition temperature of 0 ° C. or lower, a storage elastic modulus (E ′) at 20 ° C. of 1 × 10 ³ MPa or lower, and a melting point of 90 ° C. or higher.

Furthermore, the crystal nucleating agent has the ability to give the polylactic acid polymer the property of forming crystals when the temperature is lowered from the melting point of the polylactic acid polymer to the glass transition temperature at a rate of 10 ° C./min. It is preferable to use it.
A molded object can be obtained using said biodegradable composite sheet.

One layer composed of the mixture containing the polylactic acid polymer of the present invention and the crystal nucleating agent is a surface in contact with the molding die. In this one layer, there is no component that melts at the time of molding, there is no deformation due to adhesion when taking out from the mold, and the component does not exude to the outside and stickiness occurs. Good moldability and Mold releasability can be obtained and heat resistance can be imparted.
Also, a mixture composed of a biodegradable aliphatic polyester and a crystal nucleating agent, or a mixture composed of a biodegradable aliphatic polyester and a crystal nucleating agent excluding a polylactic acid-based polymer and a polylactic acid-based polymer. The other layer composed of can impart heat resistance and impact resistance.

  According to the present invention, both outer layers of the laminate are composed of an outer layer resin containing a polylactic acid polymer and a crystal nucleating agent, so there is no component that melts during molding, and deformation occurs when taking out from the mold. And the component does not ooze out and stickiness is not generated, and good moldability can be obtained and heat resistance can be imparted.

  Further, at least one inner layer of the laminate is composed of an inner layer resin containing a decomposable resin selected from a polylactic acid polymer or a biodegradable aliphatic polyester and a crystal nucleating agent. And impact resistance can be imparted.

Embodiments of the present invention will be described below.
The biodegradable composite sheet according to the present invention is formed from a laminate having at least two layers. Specifically, the biodegradable composite sheet is formed from one layer that contacts the molding die and the other layer that does not contact the molding die.

  One layer in contact with the molding die is composed of a mixture containing a polylactic acid polymer and a crystal nucleating agent. The other layer not in contact with the molding die is composed of a mixture containing a biodegradable aliphatic polyester excluding a polylactic acid polymer and a crystal nucleating agent. The mixture constituting the other layer may contain a polylactic acid polymer together with a biodegradable aliphatic polyester excluding the polylactic acid polymer.

When the laminate has at least three layers, the one layer forms the outer layers of the laminate, and the other layer includes at least one of the inner layers sandwiched between the outer layers of the laminate. It is preferable to form. If it does in this way, since the outer surface of the obtained laminated body is covered with said one layer, favorable moldability and mold release property can be exhibited.
In this case, as long as the other layers which are not formed by the other layer among the inner layers do not impair the characteristics of the biodegradable composite sheet according to the present invention, any layer structure can be adopted.

  The polylactic acid polymer used in the above layer is a homopolymer having a structural unit of L-lactic acid or D-lactic acid, that is, poly (L-lactic acid) or poly (D-lactic acid), and the structural unit is L- It refers to a copolymer that is both lactic acid and D-lactic acid, that is, poly (DL-lactic acid) and a mixture thereof, and further a copolymer with α-hydroxycarboxylic acid or diol / dicarboxylic acid. May be.

  As a polymerization method of the polylactic acid polymer, any known method such as a condensation polymerization method or a ring-opening polymerization method can be adopted. For example, in the condensation polymerization method, a polylactic acid polymer having an arbitrary composition can be obtained by directly dehydrating condensation polymerization of L-lactic acid, D-lactic acid, or a mixture thereof.

  In the ring-opening polymerization method, a polylactic acid-based polymer can be obtained using a selected catalyst while using lactide, which is a cyclic dimer of lactic acid, with a polymerization regulator or the like as necessary. Lactide includes L-lactide, which is a dimer of L-lactic acid, D-lactide, which is a dimer of D-lactic acid, and DL-lactide composed of L-lactic acid and D-lactic acid. By mixing and polymerizing, a polylactic acid polymer having an arbitrary composition and crystallinity can be obtained.

  Furthermore, non-aliphatic diols such as non-aliphatic dicarboxylic acids such as terephthalic acid, ethylene oxide adducts of bisphenol A, and the like may be used as small-scale copolymerization components as required to improve heat resistance.

  Furthermore, a small amount of a chain extender such as a diisocyanate compound, an epoxy compound, or an acid anhydride can be used for the purpose of increasing the molecular weight.

  The other hydroxy-carboxylic acid unit copolymerized with the polylactic acid polymer is an optical isomer of lactic acid (D-lactic acid for L-lactic acid, L-lactic acid for D-lactic acid). ), Glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxy-n-butyric acid, 2-hydroxy3,3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, 2-methyllactic acid, 2-hydroxycaprone Examples thereof include bifunctional aliphatic hydroxy-carboxylic acids such as acids and lactones such as caprolactone, butyrolactone and valerolactone.

  Examples of the aliphatic diol copolymerized with the polylactic acid polymer include ethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol and the like. Examples of the aliphatic dicarboxylic acid include succinic acid, adipic acid, suberic acid, sebacic acid, and dodecanedioic acid.

  The preferred range of the weight average molecular weight of the polylactic acid-based polymer is 50,000 to 400,000, preferably 100,000 to 250,000, and practical properties are hardly expressed when below this range. The melt viscosity is too high and the molding processability is poor.

  The biodegradable aliphatic polyester excluding the polylactic acid-based polymer according to the present invention is a component for imparting heat resistance and impact resistance, and is an aliphatic having biodegradability excluding the polylactic acid-based polymer. This refers to polyester. As this biodegradable aliphatic polyester, polyhydroxycarboxylic acid excluding polylactic acid, aliphatic polyester or aliphatic aromatic polyester obtained by condensing aliphatic diol and aliphatic dicarboxylic acid or aromatic dicarboxylic acid, cyclic Examples thereof include aliphatic polyesters obtained by ring-opening polymerization of lactones, synthetic aliphatic polyesters, and aliphatic polyesters biosynthesized in cells.

  Examples of the polyhydroxycarboxylic acid excluding the polylactic acid include 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxy-n-butyric acid, 2-hydroxy-3,3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, Examples thereof include homopolymers and copolymers of hydroxycarboxylic acids such as 2-methyllactic acid and 2-hydroxycaproic acid.

Examples of the aliphatic diol include ethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol and the like. Examples of the aliphatic dicarboxylic acid include succinic acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid and the like.
Examples of the aromatic dicarboxylic acid include terephthalic acid and isophthalic acid.

  Aliphatic polyesters obtained by condensing these aliphatic diols and aliphatic dicarboxylic acids, and aliphatic aromatic polyesters obtained by condensing aliphatic diols, aliphatic dicarboxylic acids and aromatic dicarboxylic acids, One or more compounds can be selected from each of the compounds and subjected to condensation polymerization, and further, if necessary, jumped up with an isocyanate compound or the like to obtain a desired polymer.

  The aliphatic polyester obtained by ring-opening polymerization of the above cyclic lactones can be obtained by polymerizing one or more of ε-caprolactone, δ-valerolactone, β-methyl-δ-valerolactone and the like as a cyclic monomer.

  Examples of the synthetic aliphatic polyester include copolymers of cyclic acid anhydrides and oxiranes such as succinic anhydride and ethylene oxide, propylene oxide.

  Examples of the aliphatic polyester biosynthesized in the microbial cells include aliphatic polyesters biosynthesized by acetyl coenteam A (acetyl CoA) in the microbial cells including Alkali geneus eutrophus. The aliphatic polyester biosynthesized in the cells is mainly poly-β-hydroxybutyric acid (poly-3HB), but is copolymerized with hydroxyvaleric acid (HV) to improve the practical properties of plastics. It is industrially advantageous to make a copolymer of poly (3HB-CO-3HV). The HV copolymerization ratio is generally preferably 0 to 40 mol%. Furthermore, instead of hydroxyvaleric acid, a long-chain hydroxyalkanoate such as 3-hydroxyhexanoate, 3-hydroxyoctanoate, and 3-hydroxyoctadecanoate may be copolymerized.

  The glass transition temperature of the biodegradable aliphatic polyester is preferably 0 ° C. or lower, and more preferably −20 ° C. or lower. If it is higher than 0 ° C, the impact resistance improving effect may be insufficient.

The storage elastic modulus (E ′) at 20 ° C. of the biodegradable aliphatic polyester is preferably 1 × 10 ³ Mpa or less. If it is greater than 1 × 10 ³ Mpa, the impact resistance improving effect may be insufficient.

  Furthermore, the melting point of the biodegradable aliphatic polyester is preferably 90 ° C. or higher, and more preferably 100 ° C. or higher. If it is lower than 90 ° C., the heat resistance may be insufficient.

  The crystal nucleating agent used in the above layer refers to a material that promotes crystallization of the polylactic acid polymer and imparts heat resistance to the molded body. Specifically, from the melting point of the polylactic acid polymer to the glass transition temperature. Those having the ability to give the polylactic acid polymer the ability to form crystals when the temperature is lowered at a rate of 10 ° C./min are preferred.

The crystal nucleating agent used for one layer in contact with the above molding die is used for the layer in contact with the molding die in addition to providing the above moldability, and thus the layer is sticky and sticky. In order to prevent this, a material that does not melt or soften at the mold temperature is preferable. Examples thereof include inorganic compounds, aliphatic carboxylic acid amides, aliphatic carboxylates and the like.
Specific examples of the inorganic compound include talc, silica, kaolinite, and charcoal.

  Specific examples of the aliphatic carboxylic acid amide include lauric acid amide, palmitic acid amide, stearic acid amide, erucic acid amide, behenic acid amide, N-stearyl stearic acid amide, methylol stearic acid amide, and methylol behenine. Acid amide, dimethylol oil amide, dimethyl lauric acid amide, dimethyl stearic acid amide, ethylene bis oleic acid amide, ethylene bis stearic acid amide, ethylene bis lauric acid amide, hexamethylene bis oleic acid amide, butylene bis stearic acid amide, m- Xylylene bis-stearic acid amide, m-xylylene bis-12 hydroxystearic acid amide, N, N′-dioleyl adipic acid amide, N, N′-distearyl adipic acid amide, N, N′-distearyl iso Talamide, N, N'-distearyl terephthalamide, N-butyl-N'stearyl urea, N-propyl-N'stearylurea, N-allyl-N'stearylurea, N-stearyl-N'stearylurea Etc.

  Further, examples of the aliphatic carboxylate include sodium laurate, potassium laurate, potassium hydrogen laurate, magnesium laurate, calcium laurate, zinc laurate, silver laurate, lithium myristate, sodium myristate, myristin. Potassium hydrogen hydride, magnesium myristate, calcium myristate, zinc myristate, silver myristate, lithium palmitate, potassium palmitate, magnesium palmitate, calcium palmitate, zinc palmitate, copper palmitate, lead palmitate, palmitate Thallium, cobalt palmitate, sodium oleate, potassium oleate, magnesium oleate, calcium oleate, zinc oleate, lead oleate, thallium oleate Copper oleate, nickel oleate, sodium stearate, lithium stearate, magnesium stearate, calcium stearate, barium stearate, aluminum stearate, thallium stearate, lead stearate, nickel stearate, bevelium stearate, sodium isostearate , Potassium isostearate, magnesium isostearate, calcium isostearate, barium isostearate, aluminum isostearate, zinc isostearate, nickel isostearate, sodium behenate, potassium behenate, magnesium behenate, calcium behenate, barium behenate, behenine Aluminum oxide, zinc behenate, nickel behenate, sodium montanate , Potassium montanate, magnesium montanate, calcium montanate, barium montanate, aluminum montanate, zinc montanate, montanic acid nickel, and the like.

  In addition, the crystal nucleating agent used for the other layer that does not come into contact with the molding die is particularly problematic because even if stickiness occurs, the adhesive or sticky component is blocked in the layer that comes into contact with the die. Must not. For this reason, the crystal nucleating agent used in this layer may be one having the above heat-resistant characteristics. Examples of this include the crystal nucleating agent used in one layer in contact with the molding die. , Difatty acid esters, animal and vegetable oils, fatty acids, aliphatic alcohols, waxes and the like.

  Specific examples of the difatty acid ester include dimethyl adipate, di-2-ethylhexyl adipate, diisobutyl adipate, dibutyl adipate, diisodecyl adipate, dibutyl diglycol adipate, di-2-ethylhexyl adipate, dibutyl sebagate, di-2-ethylhexyl. Seba gate, etc.

  Specific examples of the animal and vegetable oils include palm oil, palm oil, linseed oil, epoxidized linseed oil, soybean oil, epoxidized soybean oil, cottonseed oil, rapeseed oil, tung oil, castor oil, beef tallow, squalane, lanolin, Hardened oil and the like.

  Furthermore, specific examples of the fatty acid include stearic acid, lauric acid, palmitic acid, behenic acid, caprylic acid, capric acid, oleic acid, myristic acid, and montanic acid.

  Furthermore, examples of the aliphatic alcohol include aliphatic monoalcohols such as pentadecyl alcohol, cetyl alcohol, heptadecyl alcohol, stearyl alcohol, nonadecyl alcohol, eicosyl alcohol, seryl alcohol, 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, And cyclic alcohols such as cyclohexane-1,2-diol and cyclohexane-1,4-diol.

  Examples of the waxes include animal waxes, plant waxes, mineral waxes, petroleum waxes and the like.

  The composition ratio of the polylactic acid polymer and the crystal nucleating agent in one layer in contact with the molding die is preferably 0.5 to 50 parts by weight of the crystal nucleating agent with respect to 100 parts by weight of the polylactic acid polymer. 5 to 30 parts by weight is more preferable. When the amount is less than 0.5 part by weight, the function as a crystal nucleating agent is insufficient, and the crystal accelerating effect of the polylactic acid polymer is poor. On the other hand, when the amount is more than 50 parts by weight, other physical properties are adversely affected. The case comes out.

  Further, the composition ratio of the biodegradable aliphatic polyester excluding the polylactic acid polymer to the entire laminate, that is, the biodegradable composite sheet 100 parts by weight is preferably 3 to 80 parts by weight, Part by weight is more preferred. If the amount is less than 3 parts by weight, the impact resistance improving effect is poor. On the other hand, if the amount is more than 80 parts by weight, the elastic modulus of the entire sheet is lowered, and deformation may occur at the time of mold release.

  The biodegradable composite sheet according to the present invention can be produced by a commonly used method. For example, a method of co-extrusion that connects a plurality of extruders to a single die in a feed block type or a multi-manifold type, using a roll or a press plate with another type of film on the surface of the unwound film For example, a method of thermocompression bonding.

The thickness of the biodegradable composite sheet according to the present invention is not particularly limited, and is appropriately selected depending on the desired thickness of the molded article.
The biodegradable composite sheet according to the present invention can be formed using a method such as vacuum forming or pressure forming. The molded body thus obtained can be used as various containers.

  Hereinafter, although this invention is demonstrated in detail using an Example, this invention does not receive a restriction | limiting at all by these. In addition, the physical-property value in an Example and a comparative example was measured and evaluated by the following method, and the used polylactic acid-type polymer was manufactured by the following method.

(Measurement and evaluation of physical properties, etc.)
<1> Heat resistance The obtained molded body was filled with 85 ° C. hot water and allowed to stand for 30 minutes, and then the presence or absence of deformation of the molded body was visually confirmed.
<2> Impact resistance (1)
Using a Toyo Seiki Co., Ltd. Hydroshot Impact Tester (model HMT-1), hitting a 1/2 inch diameter striker at a speed of 3 m / sec at a temperature of 23 ° C. The energy required was calculated.

<3> Impact resistance (2)
The obtained molded body was filled with water, the opening was sealed and dropped onto the concrete from a height of 1 m, and the molded body was examined for damage.
<4> Storage elastic modulus (E ')
Based on JIS-K-7198 method A, the storage elastic modulus (E ′) of a biodegradable aliphatic polyester using a range of −50 to 200 ° C. at a frequency of 1 Hz and a temperature rising temperature of 3 ° C./min was measured. .

<5> Glass Transition Temperature Based on JIS-K-7121, the glass transition temperature of the biodegradable aliphatic polyester used at a temperature elevation temperature of 10 ° C./min was measured by differential scanning calorimetry (DSC).
<6> Melting Point Based on JIS-K-7121, the melting point of the biodegradable aliphatic polyester was measured by a differential scanning calorimetry (DSC) at a temperature rising rate of 10 ° C./min.

<7> Crystallization temperature Based on JIS-K-7121, the crystallization temperature of the polylactic acid-type polymer in the sheet | seat obtained at the temperature-fall temperature of 10 degrees C / min by the differential scanning calorimetry (DSC) was measured.
<8> Formability Using a heated mold with a diameter of 100 mm, a depth of 30 mm, and a drawing ratio of 0.3, the resulting sheet is vacuum-formed to obtain a molded body. At this time, the molded state and release from the mold The sex was confirmed.

<9> Stickiness The molded product obtained in the above-described moldability test was touched by hand to check for stickiness.

(Manufacture of polylactic acid polymer)
In a 500 liter batch polymerization apparatus equipped with a stirrer and a heating apparatus, 97 kg of L-lactide (trade name: PURASORB L) manufactured by Pulac Japan, 3 kg of DL-lactide (trade name: PURASORB DL) manufactured by the same company, and octyl acid 15 ppm of tin was added. After nitrogen substitution, polymerization was performed at 185 ° C. and a stirring speed of 100 rpm for 60 minutes. The obtained melt was subjected to a 40 mmφ co-directional twin-screw extruder manufactured by Mitsubishi Heavy Industries, Ltd. equipped with three stages of vacuum vents and extruded into a strand at 200 ° C. while degassing at a vent pressure of 4 torr and pelletized. . The obtained polylactic acid polymer had a weight average molecular weight of 200,000 and an L-form content of 98.3%.

(Example 1)
10 parts by weight of a crystal nucleating agent (talc, manufactured by Nippon Talc Co., Ltd .: Microace L1) is mixed with 100 parts by weight of the polylactic acid polymer obtained by the above production method, and the same direction biaxial stretching extruder. After being melt-kneaded and discharged onto the strand, it was cut into pellets with a pelletizer to obtain outer layer pellets.
On the other hand, 90 parts by weight of the polylactic acid polymer obtained by the above method, 10 parts by weight of biodegradable aliphatic polyester (aliphatic aromatic polyester, manufactured by BASF: Ecoflex), and crystal nucleating agent (talc, Japan) Talc Co., Ltd .: Microace L1) 10 parts by weight are mixed, fed to the same direction twin screw extruder, melt-kneaded and discharged in the form of strands, then cut into pellets with a pelletizer, and pellets for the inner layer Got.

The pellets for the outer layer and the pellets for the inner layer are respectively supplied to each single-screw extruder, the outer layer and the inner layer are merged using a feed block, extruded from one T die, and the layer configuration is outer layer / inner layer / outer layer = 50 / A biodegradable composite sheet having 300/50 (unit: μm) and a total thickness of 400 μm was obtained.
The obtained biodegradable composite sheet was subjected to vacuum forming using a heating mold, and subsequently subjected to crystallization treatment at 110 ° C. for 20 seconds with the same mold to obtain a molded body.
In addition, when the glass transition point, melting | fusing point, and E 'of the biodegradable aliphatic polyester used (aliphatic aromatic polyester, the BASF company make: Ecoflex) were measured by said method, glass transition temperature-30 degreeC, The melting point was 112 ° C. and E ′ = 1 × 10 ² MPa.
Using the obtained biodegradable composite sheet or molded article, the physical property values and the like were measured and evaluated. The results are shown in Table 1.

(Example 2)
In the same manner as in Example 1, except that the composition ratio of the inner layer pellet was polylactic acid polymer / biodegradable aliphatic polyester / crystal nucleating agent = 70/30/10 (unit: parts by weight), A decomposable composite sheet and a molded body were obtained.
Using the obtained biodegradable composite sheet or molded article, the physical property values and the like were measured and evaluated. The results are shown in Table 1.

(Example 3)
A biodegradable composite sheet and a molded body were obtained in the same manner as in Example 1 except that Eastman Chemical Co., Ltd .: Ester Bio Ultra was used as the biodegradable aliphatic polyester constituting the inner layer.
In addition, when the glass transition point, melting | fusing point, and E 'of the biodegradable aliphatic polyester (Eastman Chemical Co., Ltd. product) used were measured by said method, glass transition temperature -30 degreeC, melting | fusing point 110 C. and E ′ = 1 × 10 ² MPa.
Using the obtained biodegradable composite sheet or molded article, the physical property values and the like were measured and evaluated. The results are shown in Table 1.

Example 4
A biodegradable composite sheet and a molded body were obtained in the same manner as in Example 1 except that Showa High Polymer Co., Ltd .: Bionore 1001 was used as the biodegradable aliphatic polyester constituting the inner layer.
In addition, when the glass transition point, melting | fusing point, and E 'of the biodegradable aliphatic polyester (Showa Polymer Co., Ltd. product: Bionore 1001) used were measured by said method, glass transition temperature -40 degreeC, melting | fusing point 114 degreeC E ′ = 8 × 10 ² MPa.
Using the obtained biodegradable composite sheet or molded article, the physical property values and the like were measured and evaluated. The results are shown in Table 1.

(Example 5)
A biodegradable composite sheet and a molded body were obtained in the same manner as in Example 2 except that the thickness of the biodegradable composite sheet was changed to outer layer / inner layer / outer layer = 25/350/25 (unit: μm).
Using the obtained biodegradable composite sheet or molded article, the physical property values and the like were measured and evaluated. The results are shown in Table 1.

(Comparative Example 1)
Other than polylactic acid polymer alone (without crystal nucleating agent) as outer layer and polylactic acid polymer / biodegradable aliphatic polyester = 90/10 (unit: parts by weight) (without crystal nucleating agent) as inner layer Obtained a sheet and a molded body in the same manner as in Example 1.
Using the obtained sheet or molded article, the above physical properties were measured and evaluated. The results are shown in Table 1.

(Comparative Example 2)
The outer layer pellets obtained in Example 1 were supplied to a single screw extruder and extruded from a T die to obtain a single layer sheet. The obtained sheet was subjected to vacuum forming using a heating mold and subsequently subjected to crystallization treatment at 110 ° C. for 20 seconds with the same mold to obtain a molded body.
Using the obtained sheet or molded article, the above physical properties were measured and evaluated. The results are shown in Table 1.

(Comparative Example 3)
The pellets for the inner layer obtained in Example 1 were supplied to a single screw extruder and extruded from a T die to obtain a single layer sheet. The obtained sheet was subjected to vacuum forming using a heating mold and subsequently subjected to crystallization treatment at 110 ° C. for 20 seconds with the same mold to obtain a molded body.
Using the obtained sheet or molded article, the above physical properties were measured and evaluated. The results are shown in Table 1.

(Comparative Example 4)
100 parts by weight of the polylactic acid polymer obtained by the above production method is supplied to the same direction biaxial stretching extruder, melt-kneaded and discharged onto the strand, then cut into pellets with a pelletizer, Obtained.
The obtained pellets were supplied to a single screw extruder and extruded from a T die to obtain a single layer sheet. The obtained sheet was subjected to vacuum forming using a heating mold and subsequently subjected to crystallization treatment at 110 ° C. for 20 seconds with the same mold to obtain a molded body.
Using the obtained sheet or molded article, the above physical properties were measured and evaluated. The results are shown in Table 1.

(result)
In Examples 1 to 5, there were no problems in impact resistance, heat resistance, moldability, and stickiness, and good molded articles were obtained.
In Comparative Example 1, since the crystal nucleating agent is not contained, the crystallization of the polylactic acid polymer is not sufficiently advanced in the vacuum molding die, and the molded body is deformed when taken out from the die, The heat resistance was also insufficient.

In Comparative Example 2, there was no problem with respect to heat resistance and moldability, but since there was no biodegradable aliphatic polyester imparting impact resistance, the hydroshot impact value was as low as 28 kgf · mm, and molding was performed by a drop test. Cracks in the body were observed.
In Comparative Example 3, there was no problem with respect to impact resistance and heat resistance. However, when the mold was released from the mold after vacuum molding, there was a mold release failure that was probably caused by the adhesion of the biodegradable aliphatic polyester. Occurred and the molded body was deformed.
In Comparative Example 4, there were problems in all of impact resistance, heat resistance, and moldability.

Claims (3)

  A biodegradable composite sheet formed from a laminate having at least three layers, wherein both outer layers of the laminate are composed of a mixture containing a polylactic acid polymer and a crystal nucleating agent. At least one of the inner layers sandwiched between the two outer layers is a biodegradation composed of a mixture containing a biodegradable aliphatic polyester (excluding aliphatic aromatic polyesters) excluding polylactic acid polymers and a crystal nucleating agent. The manufacturing method of a molded object which manufactures a molded object by the method of vacuum forming or pressure forming using a property composite sheet.   The method for producing a molded article according to claim 1, wherein the mixture constituting at least one of the inner layers contains a polylactic acid polymer.   The composition ratio of the crystal nucleating agent with respect to 100 parts by weight of the polylactic acid polymer contained in both outer layers is 0.5 to 50 parts by weight, and the polylactic acid polymer with respect to 100 parts by weight of the whole laminate is The method for producing a molded article according to claim 1 or 2, wherein the composition ratio of the biodegradable aliphatic polyester is 3 to 80 parts by weight.