CN1860026A - Biodegradable layered sheet - Google Patents

Abstract

It is an object to provide a biodegradable laminated sheet which is high in heat resistance, impact resistance and strength when subjected to loads at high temperature, does not develop wrinkles called 'bridges', which can be easily deep-drawn or formed into blister articles, which are typically complicated in shape. The biodegradable sheet is a laminated sheet comprising at least two layers. Each of the layers forming the laminated sheet is a resin composition comprising 75 to 25% by mass of a polylactic acid resin, and 25 to 75% by mass of a polyester resin having a glass transition temperature not exceeding 0 degrees C and a melting point higher than the glass transition temperature of the polylactic acid resin, and not exceeding the melting point of the polylactic acid resin, based on 100 mass percent of the total amount of the polylactic acid resin and the polyester resin. The D-lactic acid content of the polylactic acid resin contained in one layer, and the D-lactic acid content of the polylactic acid resin in the other layer are determined to satisfy a predetermined relationship. The laminated sheet is subjected to crystallization treatment.

Description

biodegradable laminate

Technical field

The present invention relates to biodegradable laminates, articles made from such laminates, and methods of forming the articles.

Background technique

Plastics such as polyethylene, polypropylene, polyvinyl chloride, polystyrene, and polyethylene terephthalate have been used for food containers (such as cups and plates), blister packs, hot-fill containers, delivery Materials such as trays and carrier tapes for electronic components.

These plastic items are usually thrown away shortly after use, and how to dispose of them such as incineration or landfill is now an important issue. Specifically, these resins such as polyethylene, polypropylene, and polystyrene have a high calorific value when incinerated, so when they are burned in an incinerator, they tend to damage the incinerator. Harmful gases are produced when PVC is burned. If these plastics are landfilled, they tend to fill up landfills in the short term, as they remain semi-permanently in the soil due to their chemical stability, which hardly decomposes in the natural environment. If dumped in the natural environment, they can damage landscapes or destroy habitats for marine animals.

Therefore, in order to protect the environment, biodegradable materials are currently being actively developed. One of such biodegradable materials is polylactic acid resin. Since polylactic acid resin is biodegradable, it is naturally hydrolyzed in soil or water, and is decomposed into harmless substances by microorganisms. In addition, since its heat of combustion is low, it does not damage the incinerator even when incinerated. Also, since polylactic acid resin is derived from plants, it does not depend on crude oil—one of the natural resources expected to be depleted.

However, since polylactic acid resin has low heat resistance, it is considered unsuitable as a material for containers used at high temperatures, such as containers for storing food to be heated or boiling water. In addition, if polylactic acid resin sheets or products made of such sheets are stored in warehouses or transported in trucks or ships, they tend to deform or fuse to each other because the interior of these warehouses, trucks or ships heats up to high temperatures, for example, in summer.

Patent Document 1 discloses a technology for improving the heat resistance of polylactic acid resin by keeping the polylactic acid resin in a mold at a temperature close to the crystallization temperature of the polylactic acid resin (80-130° C.), thereby making the polylactic acid resin highly crystallized.

It is known from Patent Document 2 that by pre-crystallizing a single-layer sheet made of a resin composition comprising polylactic acid resin and polyester, heat resistance, impact resistance, and formability of an article formed from the single-layer sheet can be improved sex.

Patent Document 1: JP 8-193165A

Patent Document 2: JP 2003-147177A

Contents of invention

The problem to be solved by the present invention

However, in the foregoing method, since the molded polylactic acid crystallizes in the mold, the molded polylactic acid resin must be held in the mold while crystallizing, making the molding cycle longer than that in general, which increases production cost. Furthermore, a heating device for heating the mold is additionally required.

Regarding the single-layer board of Patent Document 2, if a plurality of products are formed from the single-layer board using a multi-cavity mold, wrinkles called "bridging phenomenon" are generated on the products depending on their shapes. The formability of the molded article is slightly deteriorated for an article formed by deep drawing the plate using a vacuum forming machine or a blister article having a complicated shape formed from the above plate.

The object of the present invention is to provide a biodegradable laminated board, which does not cause environmental problems and has high heat resistance under high temperature load, and products formed using the biodegradable laminated board , impact resistance and strength, does not produce wrinkles called "bridging", and is easy to deep draw or form into bubble products that often have complex shapes.

A solution to the problem described

According to the present invention, in order to achieve the above object, there is provided a biodegradable laminated board comprising at least two layers, each of the at least two layers comprising a resin composition comprising 75 to 25% by mass Polylactic acid resin and 25-75% by mass of polyester resin, the polyester resin has a glass transition temperature not exceeding 0°C, and a melting point higher than the glass transition temperature of the polylactic acid resin but not exceeding the melting point of the polylactic acid resin , the total amount of the polylactic acid resin and the polyester resin is based on 100% by mass, wherein the D-lactic acid content Da (%) of the polylactic acid resin contained in one layer of the at least two layers is the same as that in the at least two layers The D-lactic acid content Db (%) of the polylactic acid resin that another layer comprises satisfies the following relational formula (1):

Da≤7 and Db-Da＞3 (1)

The laminate was subjected to crystallization treatment.

Advantages of the invention

Since the laminate of the present invention contains polylactic acid resin and polyester resin, it does not cause any environmental problems.

Since the laminated board of the present invention includes a first layer having a D-lactic acid content of not more than 7%, and a second layer having a D-lactic acid content greater than the D-lactic acid content of the first layer by 3% or more, when the laminated board When crystallized, the first layer low in D-lactic acid crystallized more easily than the second layer. Thus, the laminate of the present invention includes not only layers that crystallize before forming, but also layers that are less likely to crystallize. This eliminates the need to keep the mold temperature close to the crystallization temperature of polylactic acid resin (80-130° C.) to promote laminate crystallization, making it possible to form laminates using molds kept at normal temperatures during normal molding cycles. The articles thus formed have sufficient heat resistance.

Since the laminate according to the invention comprises layers which are difficult to crystallize, deep-drawn and air-bubble products generally having complex shapes can be formed from the laminate according to the invention.

The laminate according to the present invention contains a polyester resin having a specific glass transition temperature (Tg) and melting point, and products formed from the laminate have high heat resistance, impact resistance, formability and high temperature resistance. strength under load. They also rarely develop the so-called "bridging phenomenon" of wrinkles.

Description of drawings

Fig. 1 is a graph showing a typical relationship between the dynamic viscoelasticity of a biodegradable laminate according to the present invention and its temperature.

Detailed ways

The biodegradable laminate according to the present invention comprises at least two layers, each layer comprising a resin composition comprising a polylactic acid resin and a prescribed polyester resin.

Polylactic acid resin is a polymer obtained by polycondensation of a monomer containing lactic acid as its main component. There are two types of lactic acid, L-lactic acid and D-lactic acid, which are optical isomers. Polylactic acid resins have different degrees of crystallinity according to the ratio of the two lactic acid contents. Random copolymers comprising L-lactic acid and D-lactic acid in a ratio of 80:20 to 20:80 are completely amorphous transparent polymers without crystallinity. It softens at a glass transition temperature around 60°C.

The random copolymer comprising L-lactic acid and D-lactic acid in a ratio of 100:0 to 80:20 or 20:80 to 0:100 has crystallinity. Although its crystallinity depends on the content ratio of L-lactic acid and D-lactic acid, its glass transition temperature is about the same as that of the previous copolymer, that is, about 60°C. By melt extrusion of the copolymer and rapid cooling shortly after melt extrusion, it is transformed into a highly transparent amorphous material. Then, if cooled slowly, it transforms into a crystalline material. A homopolymer, that is, a polymer containing only L-lactic acid or D-lactic acid, is a semi-crystalline polymer having a melting point of not less than 180°C.

The polylactic acid resin used in the present invention can be the homopolymer containing L-lactic acid or D-lactic acid as its structural unit, i.e. poly(L-lactic acid) or poly(D-lactic acid); containing L-lactic acid and D-lactic acid A copolymer of its structural units, namely poly(DL-lactic acid); or a mixture thereof. It may also be a copolymer of the aforementioned polymers with other hydroxycarboxylic acids or diols/dicarboxylic acids. It may also contain small amounts of residues of chain extenders.

The polylactic acid resin can be polymerized by a known method such as polycondensation or ring-opening polymerization. In polycondensation, polylactic acid having a desired composition can be obtained by directly subjecting L-lactic acid, D-lactic acid or a mixture thereof to dehydration polycondensation.

In the ring-opening polymerization (lactide method), polylactic acid can be obtained from lactide and cyclic dimer of lactic acid, and a selective catalyst with polymerization regulation can be added if necessary.

The aforementioned other hydroxycarboxylic acids to be copolymerized with polylactic acid may be optical isomers of lactic acid (for example, D-lactic acid when the lactic acid is L-lactic acid, and L-lactic acid when the lactic acid is D-lactic acid); difunctional group Aliphatic hydroxycarboxylic acids such as glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxy-n-butyric acid, 2-hydroxy-3,3-dimethylbutyric acid, 2-hydroxy-3-methanoic acid butyric acid, 2-methyllactic acid and 2-hydroxycaproic acid; and lactones such as caprolactone, butyrolactone and valerolactone.

The aliphatic diol to be copolymerized with the polylactic acid polymer may be ethylene glycol, 1,4-butanediol or 1,4-cyclohexanedimethanol. The aforementioned aliphatic dicarboxylic acid may be succinic acid, adipic acid, suberic acid, sebacic acid or dodecanedioic acid.

Furthermore, as a small amount of copolymerization components, ethylene oxide adducts of non-aliphatic dicarboxylic acids such as terephthalic acid and/or non-aliphatic diols such as bisphenol A may be used as required.

The weight average molecular weight of the polylactic acid resin used in the present invention is preferably 60,000 to 700,000, more preferably 80,000 to 400,000, and particularly preferably 100,000 to 300,000. If the molecular weight is too small, practical physical properties such as mechanical strength and heat resistance are hardly improved. If it is too large, the melt viscosity increases to such an extent that formability and processability are impaired.

The polyester resin specified above refers to a polyester resin having a specific glass transition temperature (Tg) and melting point. Preferably the polyester resin has a glass transition temperature (Tg) not exceeding 0°C, more preferably not exceeding -20°C. If the glass transition temperature is higher than 0°C, improvement in impact resistance tends to be insufficient.

The polyester resin preferably has a melting point higher than the glass transition temperature (Tg) of the added polylactic acid resin, more preferably has a melting point of not less than 80°C. If it is below this range, the heat resistance of the product formed from this laminated board may be insufficient. The upper limit of the melting point of the polyester resin is the melting point of the added polylactic acid resin. If it is higher than the melting point of the added polylactic acid, there is no point in crystallizing the polylactic acid contained in the laminate before forming the laminate, and problems related to rigidity and formability arise. Polylactic acid resin generally has a melting point of 135 to 180° C., although it varies with the mixing ratio of structural units, ie, L-lactic acid and D-lactic acid.

By using a polyester resin having a glass transition temperature and a melting point within the above specified ranges, the resulting laminate and articles formed from the laminate will have improved heat resistance, impact resistance and formability.

Such polyester resins include biodegradable aliphatic polyesters in addition to polylactic acid resins. Such biodegradable aliphatic polyesters include aliphatic polyesters obtained by condensation of polyhydroxycarboxylic acids, aliphatic diols and aliphatic dicarboxylic acids, Aliphatic-aromatic polyesters obtained from aromatic dicarboxylic acids, aliphatic polyester copolymers obtained from aliphatic diols, aliphatic dicarboxylic acids and hydroxycarboxylic acids, obtained by ring-opening polymerization of cyclic lactones aliphatic polyesters, synthetic aliphatic polyesters, and aliphatic polyesters biosynthesized in bacteria.

The aforementioned polyhydroxycarboxylic acids include hydroxycarboxylic acids such as 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxyn-butyric acid, 2-hydroxy-3,3-dimethylbutyric acid, 2-hydroxy-3-methanoic acid Homopolymers and copolymers of methylbutyric acid, 2-methyllactic acid, and 2-hydroxyhexanoic acid.

The aforementioned aliphatic diols include ethylene glycol, 1,4-butanediol, and 1,4-cyclohexanedimethanol. The aforementioned aliphatic dicarboxylic acids include succinic acid, adipic acid, suberic acid, sebacic acid, and dodecanedioic acid. The aforementioned aromatic dicarboxylic acids include terephthalic acid and isophthalic acid.

Aliphatic polyester obtained by such condensation of aliphatic diol and aliphatic dicarboxylic acid, and aliphatic-aromatic polyester obtained by condensing aliphatic diol, aliphatic dicarboxylic acid and aromatic dicarboxylic acid , is obtained by subjecting at least one of the aforementioned compounds to polycondensation. Then, by chain extension with, for example, an isocyanate compound, the desired polymer is obtained.

The aforementioned aliphatic polyesters include polyethylene succinate, polybutylene succinate, polybutylene succinate-adipate, and polybutylene succinate-carbonate. The aforementioned aliphatic-aromatic polyesters include polybutylene adipate-terephthalate, and polybutylene succinate-adipate-terephthalate.

The aliphatic diol and aliphatic carboxylic acid used in the aliphatic polyester copolymer obtained from aliphatic diol, aliphatic dicarboxylic acid and hydroxycarboxylic acid may be those mentioned above. Moreover, the hydroxycarboxylic acid can also be L-lactic acid, D-lactic acid, DL-lactic acid, glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxy-n-butyric acid, 2-hydroxy-3,3 -Dimethylbutyric acid, 2-hydroxy-3-methyl-butyric acid, 2-methyllactic acid, 2-hydroxyhexanoic acid, etc.

The aforementioned aliphatic polyester copolymers include polybutylene succinic acid-lactic acid and polybutylene succinic-adipate-lactic acid. In this case, however, for its composition, aliphatic diol and aliphatic dicarboxylic acid are its main components. In other words, the ratio of aliphatic diol:aliphatic dicarboxylic acid:hydroxycarboxylic acid is preferably 30-49.99:35-49.99:30-0.02.

The above-mentioned aliphatic polyesters obtained by ring-opening polymerization of cyclic lactones are obtained by polymerizing one or more cyclic monomers such as ε-caprolactone, δ-valerolactone, β-methyl-δ-valerolactone derived from lactones.

The aforesaid synthetic aliphatic polyesters include copolymers of cyclic acid anhydrides and ethylene oxides, such as copolymers of succinic anhydride and ethylene oxide or propylene oxide.

The aforementioned aliphatic polyesters biosynthesized in bacteria include aliphatic polyesters biosynthesized in bacteria such as Alcaligeneseutrophus through the action of acetyl-CoA. Although this class of aliphatic polyesters mainly includes poly-β-hydroxybutyric acid (poly-3HB), it is industrially advantageous to copolymerize them with hydroxyvaleric acid (HV) to form copolymers of poly(3HB-CO-3HV) (copolymer of hydroxybutyric acid and hydroxyvaleric acid), thereby improving its practicability in plastics. The HV copolymerization ratio is preferably 0 to 40 mol%. Instead of hydroxyvaleric acid, they can be copolymerized with long-chain alkanoic acids such as 3-hydroxycaproic acid, 3-hydroxyoctanoic acid or 3-hydroxyoctadecanoic acid. Copolymers of 3HB and 3-hydroxycaproic acid include copolymers of hydroxybutyric acid and hydroxycaproic acid.

In the above resin composition, the mixing ratio (mass) of the polylactic acid resin and the polyester resin is preferably 75-25:25-75, more preferably 65:35-35:65. If the content of the polylactic acid resin is higher than 75% by mass, formability is poor, so general-purpose forming such as vacuum forming or air pressure forming is difficult. If it is less than 25% by mass, the resulting sheet and products formed from the sheet tend to be poor in rigidity.

The resin composition according to the present invention consists only of polylactic acid resin and polyester resin. In other words, actually the sum of the polylactic acid resin content and the polyester resin content is 100% by mass.

Using this resin composition, a biodegradable laminate according to the present invention was produced. The laminate should comprise multiple layers such as two, three or four layers.

If the biodegradable laminate according to the present invention comprises two layers, the D-lactic acid contents Da (%) and Db (%) in the polylactic acid resin contained in each layer (the first layer and the second layer) should be Satisfy the following relationship (1):

Da≤7 and Db-Da＞3 (1)

Specifically, the D-lactic acid content (Da) in the polylactic acid polymer forming the first layer should be not more than 7%, preferably not more than 5%. If it is higher than 7%, the degree of crystallinity tends to decrease even after the crystallization treatment, which will be described later. This results in insufficient rigidity of the laminated board when subjected to a load at a high temperature (for example, 60 to 80° C.). In other words, as the polylactic acid resin contained in the first layer, a material that can be easily crystallized in the crystallization treatment described below is preferable. The lower limit of the Da value is preferably 0.5%. If it is less than 0.5%, the resulting sheet may be brittle.

It is preferable that the D-lactic acid content (Db) in the polylactic acid polymer forming the second layer is 3% or more higher than the content Da. If the difference between Db and Da is 3% or less, the polylactic acid polymer forming the second layer is close to the polylactic acid polymer forming the first layer in terms of crystallinity and melting point, so there is no need to form a multilayer sheet. practical meaning.

The biodegradable laminate according to the invention is subjected to a crystallization treatment. The crystallization treatment promotes the crystallization of the specific polylactic acid resin. There is no specific limitation on the crystallization treatment used in the present invention as long as it promotes the crystallization of the specific polylactic acid resin. For example, crystallization via heating can be employed. In the crystallization treatment by heating, the plate can be in contact with a hot roller heated to about 60-120°C for a few seconds to several minutes, the plate can be continuously heated by an infrared heater or by hot air for a predetermined time, and the plate can also be heated Roll and heat in hot air at about 60-120°C for 0.5-72 hours.

After crystallization, the polylactic acid resin contained in the first layer preferably has a crystallinity of not less than 20% and not more than 100%, more preferably not less than 25% and not more than 99%. If it is less than 20%, the laminated board will have insufficient rigidity when subjected to a load at a high temperature (for example, 60 to 80° C.). The crystallinity of the polylactic acid resin in the first layer may be 100%.

After crystallization, the polylactic acid resin contained in the second layer preferably has a crystallinity of not less than 0% and not more than 20%, more preferably not less than 1% and less than 15%. If it is more than 20%, formability tends to be insufficient, and wrinkles so-called "bridging phenomenon" tend to occur. The crystallinity of the polylactic acid resin in the second layer may be 0%.

The polylactic acid resin contained in either the first layer or the second layer may be a mixture of two or more different types of polylactic acid resins. In this case, both the content Da and the content Db are the average D-lactic acid content in two or more polylactic acid resins.

The biodegradable laminate can be a two-layer structure, that is, a first layer/second layer structure; a three-layer structure, that is, a first layer/second layer/first layer structure; or a four-layer or four-layer structure Structure above layers, such as first layer/second layer/first layer.../second layer structure, or first layer/second layer/first layer.../first layer structure. Preferably the two outer layers consist of the first layer and at least one inner layer is the second layer. If both outer layers are composed of the first layer, both outer layers are highly crystalline, so the biodegradable laminate has high heat resistance and impact resistance, and when it is in a vacuum forming machine Or improved formability when formed in an air pressure forming machine. Between any of the first and second layers, a recycled resin layer or a layer having properties intermediate between the first and second layers may be arranged.

Preferably, the total thickness of the first layer is 3-300 microns, more preferably 10-200 microns, even more preferably 30-100 microns. If it is less than 3 microns, the rigidity of the laminated board will be insufficient when subjected to a load at a high temperature (for example, 60-80° C.). If it exceeds 300 micrometers, formability may be insufficient.

A method for producing the biodegradable laminated board according to the present invention will now be described. Each layer of the board can be formed from the above-mentioned resin composition by an ordinary board forming method. For example, the layers of the sheet can be formed by extrusion in a T-die casting process. However, since polylactic acid resin has high hygroscopicity and hydrolyzability, it is necessary to control moisture in the preparation steps. Thus, if the layers are formed by extrusion using a common single-screw extruder, the material should be dehumidified (dried) with, for example, a vacuum drier. The layers of the sheet can be formed more efficiently if extruded using a discharge-type twin-screw extruder, which dewaters the material more efficiently.

There is no limitation on the method of laminating the layers thus prepared to form a laminated board as long as it does not impair the object of the present invention. For example, the lamination method can be selected from the following four methods.

(1) Two or more extruders are used to pass through each layer of the multi-manifold or feed block type extrusion head laminate and extrude in the form of a molten sheet.

(2) One of the layers of the board is developed, and the resin as the other layer is applied by coating.

(3) After heating the layers of the board to an appropriate temperature, the layers are bonded together by hot pressing by means of a roller or a press.

(4) Layers are laminated together by means of an adhesive.

The biodegradable laminate thus formed has excellent formability, virtually no bridging, and can be formed in short cycles at temperatures achievable without heating the mold.

Specifically, the biodegradable laminate according to the present invention can be formed into a desired article by any of various methods such as vacuum forming, air pressure forming, vacuum pressure forming, and pressing. It is preferable that the molding temperature of the biodegradable laminate is not lower than the melting point of the aforementioned polyester resin but lower than the melting point of the polylactic acid resin contained in the first layer. If the molding temperature is lower than the melting point of the polyester resin, heat resistance and/or moldability may be insufficient. If the molding temperature is equal to or higher than the melting point of the polylactic acid resin contained in the first layer, problems related to rigidity and formability arise.

Thus, the biodegradable laminate according to the present invention can be molded into a desired product in a short molding cycle at a temperature much lower than the crystallization temperature of the polylactic acid resin. Therefore, it is not necessary to heat the mold to a temperature close to the crystallization temperature of the polylactic acid resin (eg, 80-130° C.). The articles thus formed have high heat resistance and impact resistance. This is presumably because the polylactic acid resin contained in the first layer of the biodegradable laminate according to the present invention is at least partially crystalline, and it may also be because the polylactic acid resin is mixed with other polyester resins, so it has unique adhesive properties. elasticity.

Fig. 1 shows the relationship between the dynamic viscoelasticity (E') of a biodegradable laminate according to the present invention and its temperature. In FIG. 1, numeral <1> indicates the glass transition temperature (Tg) of the polylactic acid resin, numeral <2> indicates the melting point of the polyester resin, and numeral <3> indicates the temperature of the polylactic acid resin contained in the first layer. melting point.

The biodegradable laminate can be molded at a temperature between <1> and <3>, but preferably molded at a temperature between <2> and <3>. Since the polylactic acid resin contained in the first layer is at least partially crystallized by the crystallization treatment, the resulting article has good heat resistance.

The biodegradable laminated board according to the present invention can be formed into the following products: lunch boxes, plates and cups for containing food such as fish, meat, fruits and vegetables, tofu, cooked food, desserts and instant noodles, toothbrushes, batteries, medicines and cosmetics Packaging containers, hot-fill containers for pudding, jam and curry powder, and trays and carrier tapes for conveying electronic components such as ICs (Integrated Circuits), transistors and diodes.

Additives may be added to the resin composition forming the biodegradable laminate according to the present invention to improve its properties. Such additives include stabilizers, antioxidants, UV absorbers, pigments, antistatic agents, conductive agents, release agents, plasticizers, flavoring agents, antibacterial agents, nucleating agents, and the like additives.

Example

Examples and comparative examples of the present invention will now be described. These examples do not limit the invention in any way. The physical properties of the examples and comparative examples of the present invention were measured and evaluated as follows.

[Measurement and evaluation]

(1) Heat resistance evaluation 1

The product formed by a male mold with a diameter of 75 mm, a depth of 50 mm, and a draw ratio of 0.67 was heat-treated at 80° C. for 20 minutes in a hot air circulation oven. The volume reduction rate is calculated as follows:

Volume reduction rate (%)={1-(volume after heat treatment of molded product/volume before heat treatment of molded product)}×100

A product with a volume reduction rate of less than 3% is excellent, a product with a volume reduction rate of not more than 6% can be used in practice, and a product with a volume reduction rate of more than 6% cannot be used.

(2) Heat resistance evaluation 2

Four products were formed using a male die with a diameter of 75 mm, a depth of 50 mm, and a draw ratio of 0.67, and filled with water. Then, openings thereof were sealed, stacked on top of each other, and heat-treated at 65° C. for 60 minutes in a hot-air circulating oven. After heat treatment, the article was inspected to see if it was deformed.

(3) Impact resistance evaluation 1

Using a water bomb impact tester manufactured by Toyo Seiki, a water bomb with a diameter of 0.5 inches was hit at a speed of 3 m/sec to each biodegradable laminate sample, and the energy required to break the laminate was calculated.

(4) Impact resistance evaluation 2

A product obtained from each biodegradable laminate sample was filled with water, its opening was sealed, and it was dropped on a concrete floor from a height of 1 m. Then watch to see if it breaks.

(5) Measurement of glass transition temperature (Tg)

According to JIS-K-7121, the glass transition temperature of polyester is measured by differential scanning calorimetry (DSC) at a heating rate of 10°C/min.

(6) Measurement of crystallization temperature

According to JIS-K-7121, the heat of fusion (ΔHm) and heat of crystallization (ΔHc) originating from the polylactic acid resin in the biodegradable sheet were measured, and the degree of crystallinity of the polylactic acid resin was calculated from these values as follows:

Crystallinity: χc%=(ΔHm-ΔHc)/(92.8×the content of polylactic acid resin in the board)×100

(7) Evaluation of formability

Using a punch with a diameter of 75 mm, a depth of 50 mm, and a draw ratio of 0.67 (mold temperature: 25° C.), the plate sample was subjected to vacuum forming (vacuum degree: −70 cmHg). The article thus formed was observed to check how it was formed, whether bridging and any other forming defects occurred. The meanings of the symbols in the table are as follows.

○: Good molding

△: Actually acceptable

×: Poor molding

(8) Overall evaluation

In the table, any samples with symbols ○ for heat resistance 1, heat resistance 2, impact resistance 1, and impact resistance 2 are represented by symbols ○; at the same time, any samples with symbols × for the above items are The samples are all represented by the symbol ×.

(composition of polylactic acid resin in the laminate)

For the polylactic acid resin forming each laminate sample, one or a mixture of Nature Works grade D-lactic acids manufactured by Cargill Dow (see Table 1), as shown in Table 2, was used. If a mixture is used, the D-lactic acid content is the average value of the D-lactic acid content of each grade of D-lactic acid in terms of its mass fraction.

Table 1 Nature Works grade 4031 4050 4060 D-lactic acid (mass%) 1.2 5 12 Tg(Tg) 58 58 56 Weight average molecular weight 200000 190000 190000

Table 2 Resin number 1 2 3 4 NatureWorks grade 4031 (mass%) 100 0 0 4050 (mass%) 0 100 70 0 4060 (mass%) 0 0 30 100 Average D-lactic acid content (mass%) 1.2 5 7.1 12

(Example 1 of the present invention)

Resin 1 in Table 2 as polylactic acid was mixed with PBS (polybutylene succinate, manufactured by Showa Highpolymer Co., Ltd.: Bionolle 1001, melting point: 111° C.; glass transition temperature: -40° C.), mixed together at the ratio of polylactic acid resin/biodegradable aliphatic polyester=50/50 (% by mass). To 100% by mass of this mixture, 10% by mass of talc (manufactured by Nippon Talc Co., Ltd.: Micro Ace L1) was added as an inorganic filler, and the mixture was extruded at 220° C. Manifold extrusion head to extrude in the form of front and back layers.

In addition, Resin 4 in Table 2 as polylactic acid and PBS of the aforementioned model as biodegradable aliphatic polyester were mixed according to polylactic acid resin/biodegradable aliphatic polyester=50/50 (% by mass) proportions are mixed together. To 100% of this mixture by mass, add 10% by mass of the aforementioned type of talc as an inorganic filler, and extrude this mixture in the form of an intermediate layer from the multi-manifold extrusion head of a parallel twin-screw extruder with a diameter of 40 mm. out.

The discharge speed of the molten resin was adjusted so that the thickness ratio of the front layer, middle layer and rear layer was 1:5:1. The layers thus extruded were brought into contact with calender rolls maintained at 110° C. to obtain a biodegradable laminate having a thickness of 300 μm. The laminate thus obtained was evaluated in the manner described above. The evaluation results are shown in Table 3.

(Example 2 of the present invention)

Resin 1 in Table 2 as polylactic acid and PBS of the aforementioned model as biodegradable aliphatic polyester were mixed at a ratio of polylactic acid resin/biodegradable aliphatic polyester=25/75 (% by mass) Mix together. To this mixture of 100% by mass, add 20% by mass of the aforementioned type of talc as an inorganic filler, and the mixture is extruded from the multi-manifold head of a parallel twin-screw extruder with a diameter of 25mm at 220°C, the previous layer and extrude in the form of the back layer.

In addition, Resin 4 in Table 2 as polylactic acid and PBS of the aforementioned model as biodegradable aliphatic polyester were calculated as polylactic acid resin/biodegradable aliphatic polyester=25/75 (mass%) proportions are mixed together. To 100% of this mixture by mass, add 20% by mass of the aforementioned type of talc as an inorganic filler, and extrude this mixture in the form of an intermediate layer from the multi-manifold extrusion head of a parallel twin-screw extruder with a diameter of 40 mm. out.

The discharge speed of the molten resin was adjusted so that the thickness ratio of the front layer, middle layer and rear layer was 1:5:1. The layers thus extruded were brought into contact with calender rolls maintained at 110° C. to obtain a biodegradable laminate having a thickness of 300 μm. The laminate thus obtained was evaluated in the manner described above. The evaluation results are shown in Table 3.

(Example 3 of the present invention)

Resin 1 in Table 2 as polylactic acid and PBS of the aforementioned model as biodegradable aliphatic polyester were used in a ratio of polylactic acid resin/biodegradable aliphatic polyester=75/25 (% by mass) Mix together. To this mixture of 100% by mass, add 10% by mass of the aforementioned type of talc as an inorganic filler, and the mixture is extruded from the multi-manifold head of a parallel twin-screw extruder with a diameter of 25mm at 220°C, the previous layer and extrude in the form of the back layer.

In addition, Resin 4 in Table 2 as polylactic acid and PBS of the aforementioned model as biodegradable aliphatic polyester were calculated on the basis of polylactic acid resin/biodegradable aliphatic polyester=75/25 (mass%) proportions are mixed together. To 100% of this mixture by mass, add 10% by mass of the aforementioned type of talc as an inorganic filler, and extrude this mixture in the form of an intermediate layer from the multi-manifold extrusion head of a parallel twin-screw extruder with a diameter of 40 mm. out.

The discharge speed of the molten resin was adjusted so that the thickness ratio of the front layer, middle layer and rear layer was 1:100:1. The layers thus extruded were brought into contact with calender rolls maintained at 110° C. to obtain a biodegradable laminate having a thickness of 300 μm. The laminate thus obtained was evaluated in the manner described above. The evaluation results are shown in Table 3.

(Example 4 of the present invention)

In addition to using PBAT (polybutylene adipate-terephthalate, manufactured by BASF, Ecoflex, melting point: 109°C, glass transition temperature: -30°C) as the biodegradable aliphatic polyester, according to the In the same manner as in Example 1, a biodegradable laminate with a thickness of 300 microns was obtained. The laminate thus obtained was evaluated in the manner described above. The evaluation results are shown in Table 3.

(Example 5 of the present invention)

Except for using PBSL (polybutylene succinic acid-lactate, manufactured by Mitsubishi Chemical Corporation: AZ81T, a copolymer of 94% by mole of succinic acid and 6% by mole of lactic acid, as the acid component, melting point: 110°C, glass transition temperature: - 40° C.) as a biodegradable aliphatic polyester, a biodegradable laminate having a thickness of 300 μm was obtained in the same manner as in Example 1. The laminate thus obtained was evaluated in the manner described above. The evaluation results are shown in Table 3.

(Example 6 of the present invention)

In addition to using PBSLA (polybutylene succinic acid-adipate-lactic acid, manufactured by Mitsubishi Chemical Corporation: AD82W, a copolymer of 74% by mole of succinic acid, 20% by mole of adipic acid and 6% by mole of lactic acid, as the acid component, melting point : 87°C, glass transition temperature: -40°C) except that biodegradable aliphatic polyester was used, a biodegradable laminate having a thickness of 300 µm was obtained in the same manner as in Example 1. The laminate thus obtained was evaluated in the manner described above. The evaluation results are shown in Table 3.

(Example 7 of the present invention)

In addition to using PBSA (polybutylene succinate-adipate, manufactured by Showa Highpolymer Co., Ltd.: Bionolle 3001, a copolymer of 85% by mole of succinic acid and 15% by mole of adipic acid, as the acid component, melting point: 93°C, Glass transition temperature: -40° C.) A biodegradable laminate having a thickness of 300 µm was obtained in the same manner as in Example 1 except that the biodegradable aliphatic polyester was used. The laminate thus obtained was evaluated in the manner described above. The evaluation results are shown in Table 3.

(Embodiment 8 of the present invention)

Resin 1 in Table 2 as polylactic acid and PBS of the aforementioned model as biodegradable aliphatic polyester were mixed at a ratio of polylactic acid resin/biodegradable aliphatic polyester=25/75 (% by mass) Mix together. To this mixture of 100% by mass, add 20% by mass of the aforementioned type of talc as an inorganic filler, and the mixture is extruded from the multi-manifold head of a parallel twin-screw extruder with a diameter of 25mm at 220°C, the previous layer and extrude in the form of the back layer.

In addition, Resin 4 in Table 2 as polylactic acid and PBS of the aforementioned model as biodegradable aliphatic polyester were calculated as polylactic acid resin/biodegradable aliphatic polyester=25/75 (mass%) proportions are mixed together. To 100% of this mixture by mass, add 20% by mass of the aforementioned type of talc as an inorganic filler, and extrude this mixture in the form of an intermediate layer from the multi-manifold extrusion head of a parallel twin-screw extruder with a diameter of 40 mm. out.

The discharge speed of the molten resin is adjusted so that the thickness ratio of the front layer, middle layer and rear layer is 1:1:1. The layers thus extruded were brought into contact with calender rolls maintained at 110° C. to obtain a biodegradable laminate having a thickness of 400 μm. The laminate thus obtained was evaluated in the manner described above. The evaluation results are shown in Table 4.

(Example 9 of the present invention)

Resin 2 in Table 2 as polylactic acid and PBS of the aforementioned model as biodegradable aliphatic polyester were used in a ratio of polylactic acid resin/biodegradable aliphatic polyester=50/50 (% by mass) Mix together. To this mixture of 100% by mass, add 10% by mass of the aforementioned type of talc as an inorganic filler, and the mixture is extruded from the multi-manifold head of a parallel twin-screw extruder with a diameter of 25mm at 220°C, the previous layer and extrude in the form of the back layer.

In addition, Resin 4 in Table 2 as polylactic acid and PBS of the aforementioned model as biodegradable aliphatic polyester were mixed according to polylactic acid resin/biodegradable aliphatic polyester=50/50 (% by mass) proportions are mixed together. To 100% of this mixture by mass, add 10% by mass of the aforementioned type of talc as an inorganic filler, and extrude this mixture in the form of an intermediate layer from the multi-manifold extrusion head of a parallel twin-screw extruder with a diameter of 40 mm. out.

The discharge speed of the molten resin was adjusted so that the thickness ratio of the front layer, middle layer and rear layer was 1:5:1. The layers thus extruded were brought into contact with calender rolls maintained at 115°C to obtain a biodegradable laminate having a thickness of 300 micrometers. The laminate thus obtained was evaluated in the manner described above. The evaluation results are shown in Table 4.

(Example 10 of the present invention)

Resin 1 in Table 2 as polylactic acid and PBS of the aforementioned model as biodegradable aliphatic polyester were used in a ratio of polylactic acid resin/biodegradable aliphatic polyester=50/50 (% by mass) Mix together. To this mixture of 100% by mass, add 10% by mass of the aforementioned type of talc as an inorganic filler, and the mixture is extruded from the multi-manifold head of a parallel twin-screw extruder with a diameter of 25mm at 220°C, the previous layer and extrude in the form of the back layer.

In addition, Resin 3 (Db=7.1) in Table 2 as polylactic acid and PBS of the aforementioned model as biodegradable aliphatic polyester were calculated on the basis of polylactic acid resin/biodegradable aliphatic polyester=50/ A ratio of 50 (% by mass) was mixed together. To 100% of this mixture by mass, add 10% by mass of the aforementioned type of talc as an inorganic filler, and extrude this mixture in the form of an intermediate layer from the multi-manifold extrusion head of a parallel twin-screw extruder with a diameter of 40 mm. out.

The discharge speed of the molten resin was adjusted so that the thickness ratio of the front layer, middle layer and rear layer was 1:5:1. The layers thus extruded were brought into contact with calender rolls maintained at 100°C to obtain a biodegradable laminate having a thickness of 300 µm. The laminate thus obtained was evaluated in the manner described above. The evaluation results are shown in Table 4.

(Example 11 of the present invention)

Resin 1 in Table 2 as polylactic acid and PBS of the aforementioned model as biodegradable aliphatic polyester were used in a ratio of polylactic acid resin/biodegradable aliphatic polyester=50/50 (% by mass) Mix together. To 100% of this mixture by mass, add 10% by mass of the aforementioned type of talc as an inorganic filler, and at 220° C., the mixture is extruded from a two-layer multi-manifold extrusion head of a parallel twin-screw extruder with a diameter of 25 mm , to extrude in the manner of the previous layer.

In addition, Resin 4 in Table 2 as polylactic acid and PBS of the aforementioned model as biodegradable aliphatic polyester were mixed according to polylactic acid resin/biodegradable aliphatic polyester=50/50 (% by mass) proportions are mixed together. To 100% of this mixture by mass, add 10% by mass of the aforementioned type of talc as an inorganic filler, and extrude this mixture in the form of an intermediate layer from the multi-manifold extrusion head of a parallel twin-screw extruder with a diameter of 40 mm. out.

Since the biodegradable laminate of this embodiment has a two-layer structure, the middle layer also serves as the rear layer of the laminate. The discharge speed of the molten resin was adjusted so that the thickness ratio of the front layer and the rear layer was 2:5. The layers thus extruded were brought into contact with calender rolls maintained at 110° C. to obtain a biodegradable laminate having a thickness of 300 μm. The laminate thus obtained was evaluated in the manner described above. The evaluation results are shown in Table 4.

(Example 12 of the present invention)

Resin 4 in Table 2 as polylactic acid and PBS of the aforementioned model as biodegradable aliphatic polyester were used in a ratio of polylactic acid resin/biodegradable aliphatic polyester=50/50 (% by mass) Mix together. To 100% of this mixture by mass, 10% by mass of the aforementioned type of talc as an inorganic filler was added, and the mixture was extruded from a multi-manifold extrusion head of a parallel twin-screw extruder with a diameter of 40 mm at 220° C. Extrude in the form of layer and back layer.

In addition, Resin 1 in Table 2 as polylactic acid and PBS of the aforementioned model as biodegradable aliphatic polyester were set at polylactic acid resin/biodegradable aliphatic polyester=50/50 (mass%) proportions are mixed together. To this mixture of 100% by mass, add 10% by mass of the aforementioned type of talc as an inorganic filler, and the mixture is extruded from the multi-manifold extrusion head of a parallel twin-screw extruder with a diameter of 25mm, with the amount of the middle layer form extrusion.

The discharge speed of the molten resin was adjusted so that the thickness ratio of the front layer, middle layer and rear layer was 3:1:3. The layers thus extruded were brought into contact with calender rolls maintained at 110° C. to obtain a biodegradable laminate having a thickness of 300 μm. The laminate thus obtained was evaluated in the manner described above. The evaluation results are shown in Table 4.

(Example 13 of the present invention)

Resin 1 in Table 2 as polylactic acid and PBS of the aforementioned model as biodegradable aliphatic polyester were used in a ratio of polylactic acid resin/biodegradable aliphatic polyester=50/50 (% by mass) Mix together. To this mixture of 100% by mass, add 10% by mass of the aforementioned type of talc as an inorganic filler, and the mixture is extruded from the multi-manifold head of a parallel twin-screw extruder with a diameter of 25mm at 220°C, the previous layer and extrude in the form of the back layer.

In addition, Resin 4 in Table 2 as polylactic acid and PBS of the aforementioned model as biodegradable aliphatic polyester were mixed according to polylactic acid resin/biodegradable aliphatic polyester=50/50 (% by mass) proportions are mixed together. To 100% of this mixture by mass, add 10% by mass of the aforementioned type of talc as an inorganic filler, and extrude this mixture in the form of an intermediate layer from the multi-manifold extrusion head of a parallel twin-screw extruder with a diameter of 40 mm. out.

The discharge speed of the molten resin was adjusted so that the thickness ratio of the front layer, middle layer and rear layer was 1:5:1. The layers thus extruded were brought into contact with calender rolls maintained at 40°C to obtain a biodegradable laminate having a thickness of 300 µm. The laminate thus prepared was rolled into a roll with a length of about 300 meters. The roll was heated in a hot air oven at 75°C for 24 hours. After heat treatment, the laminate was evaluated in the manner described above. The evaluation results are shown in Table 4.

(Example 14 of the present invention)

Resin 1 in Table 2 as polylactic acid and PBS of the aforementioned model as biodegradable aliphatic polyester were used in a ratio of polylactic acid resin/biodegradable aliphatic polyester=40/60 (% by mass) Mix together. To this mixture of 100% by mass, add 10% by mass of the aforementioned type of talc as an inorganic filler, and the mixture is extruded from the multi-manifold head of a parallel twin-screw extruder with a diameter of 25mm at 220°C, the previous layer and extrude in the form of the back layer.

In addition, Resin 4 in Table 2 as polylactic acid and PBS of the aforementioned model as biodegradable aliphatic polyester were calculated on the basis of polylactic acid resin/biodegradable aliphatic polyester = 40/60 (% by mass) . To 100% of this mixture by mass, add 10% by mass of the aforementioned type of talc as an inorganic filler, and extrude this mixture in the form of an intermediate layer from the multi-manifold extrusion head of a parallel twin-screw extruder with a diameter of 40 mm. out.

The discharge speed of the molten resin was adjusted so that the thickness ratio of the front layer, middle layer and rear layer was 1:5:1. The layers thus extruded were brought into contact with calender rolls maintained at 40°C to obtain a biodegradable laminate having a thickness of 300 µm. The laminate thus prepared was rolled into a roll with a length of about 300 meters. The roll was heated in a hot air oven at 75°C for 24 hours. After heat treatment, the laminate was evaluated in the manner described above. The evaluation results are shown in Table 4.

(comparative example 1)

To 100% by mass of resin 1 in Table 2 as polylactic acid, 10% by mass of the aforementioned type of talc as an inorganic filler was added, and the mixture was extruded at 220° C. Extrude in the layer extrusion head. The sheet thus prepared was brought into contact with calender rolls maintained at 110°C to obtain a biodegradable sheet with a thickness of 300 micrometers. The resulting panels were evaluated in the manner described above. The evaluation results are shown in Table 5.

(comparative example 2)

To 100% by mass of resin 1 in Table 2 as polylactic acid, 10% by mass of the aforementioned type of talc as an inorganic filler was added, and the mixture was extruded at 220° C. Extrude in the layer extrusion head. The sheet thus prepared was brought into contact with calender rolls maintained at 40°C to obtain a biodegradable sheet with a thickness of 300 µm. The resulting panels were evaluated in the manner described above. The evaluation results are shown in Table 5.

(comparative example 3)

Resin 4 in Table 2 as polylactic acid and PBS of the aforementioned model as biodegradable aliphatic polyester were used in a ratio of polylactic acid resin/biodegradable aliphatic polyester=80/20 (% by mass) Mix together. To 100% by mass of this mixture, add 10% by mass of the aforementioned type of talc as an inorganic filler, and extrude the mixture at 220° C. from the single-layer extrusion head of a parallel twin-screw extruder with a diameter of 25 mm . The sheet thus prepared was brought into contact with calender rolls maintained at 110°C to obtain a biodegradable sheet with a thickness of 300 micrometers. The resulting panels were evaluated in the manner described above. The evaluation results are shown in Table 5.

(comparative example 4)

Resin 1 in Table 2 as polylactic acid and PBS of the aforementioned model as biodegradable aliphatic polyester were used in a ratio of polylactic acid resin/biodegradable aliphatic polyester=80/20 (% by mass) Mix together. To 100% by mass of the mixture, 10% by mass of the aforementioned type of talc as an inorganic filler was added, and the mixture was extruded from a multi-manifold extrusion head of a parallel twin-screw extruder with a diameter of 20 mm at 220° C. Extrude in the form of layer and back layer.

In addition, Resin 4 in Table 2 as polylactic acid and PBS of the aforementioned model as biodegradable aliphatic polyester were mixed according to polylactic acid resin/biodegradable aliphatic polyester = 80/20 (% by mass) proportions are mixed together. To 100% of this mixture by mass, add 10% by mass of the aforementioned type of talc as an inorganic filler, and extrude this mixture in the form of an intermediate layer from the multi-manifold extrusion head of a parallel twin-screw extruder with a diameter of 40 mm. out.

The discharge speed of the molten resin was adjusted so that the thickness ratio of the front layer, middle layer and rear layer was 1:2:1. The layers thus extruded were brought into contact with calender rolls maintained at 110° C. to obtain a biodegradable laminate having a thickness of 300 μm. The laminate thus obtained was evaluated in the manner described above. The evaluation results are shown in Table 5.

(comparative example 5)

Resin 1 in Table 2 as polylactic acid and PBS of the aforementioned model as biodegradable aliphatic polyester were mixed at a ratio of polylactic acid resin/biodegradable aliphatic polyester=60/40 (% by mass) Mix together. To 100% by mass of this mixture, 10% by mass of the aforementioned type of talc as an inorganic filler was added, and the mixture was extruded at 220° C. from a single-layer extrusion head of a parallel twin-screw extruder with a diameter of 25 mm. The layers thus extruded were brought into contact with calender rolls maintained at 110° C. to obtain a biodegradable laminate having a thickness of 300 μm. The resulting panels were evaluated in the manner described above. The evaluation results are shown in Table 5.

(comparative example 6)

Resin 3 (Da=7.1) in Table 2 as polylactic acid and the PBS of the aforementioned model as biodegradable aliphatic polyester were calculated according to polylactic acid resin/biodegradable aliphatic polyester=60/40 ( % mass) ratios are mixed together. To 100% by mass of this mixture, 10% by mass of talc of the aforementioned type as an inorganic filler was added, and the mixture was extruded at 220° C. from the multi-manifold extrusion head of a parallel twin-screw extruder with a diameter of 25 mm, Extrude in the form of front and back layers.

In addition, Resin 4 in Table 2 as polylactic acid and PBS of the aforementioned model as biodegradable aliphatic polyester were calculated on the basis of polylactic acid resin/biodegradable aliphatic polyester=60/40 (% by mass) proportions are mixed together. To 100% of this mixture by mass, add 10% by mass of the aforementioned type of talc as an inorganic filler, and extrude this mixture in the form of an intermediate layer from the multi-manifold extrusion head of a parallel twin-screw extruder with a diameter of 40 mm. out.

The discharge speed of the molten resin was adjusted so that the thickness ratio of the front layer, middle layer and rear layer was 1:5:1. The layers thus extruded were brought into contact with calender rolls maintained at 110° C. to obtain a biodegradable laminate having a thickness of 300 μm. The laminate thus obtained was evaluated in the manner described above. The evaluation results are shown in Table 5.

table 3 Embodiments of the invention 1 2 3 4 5 6 7 biodegradable laminate full board Plate Thickness (μm) 300 layer structure three floors layer arrangement ^*1) 1/2/1 Thickness ratio 1/5/1 1/100/1 1/5/1 Db-Da (mass%) 10.8 level one Da (mass%) 1.2 Thickness (μm) 86 6 86 Crystallinity ^*2) (%) 44 45 44 47 46 40 39 polyester resin model PBS PBTA PBSL PBSLA PBSA Content (mass%) 50 75 25 50 Second floor Db% 12 Thickness (μm) 214 294 214 Crystallinity ^*2) (%) 1 1.2 1 1.3 2 1 1.3 polyester resin model PBS PBTA PBSL PBSLA PBSA Content (mass%) 50 75 25 50 evaluate Heat Resistance1 (%) 0.9 0.7 2.2 1.3 0.8 1.5 1.4 Heat resistance 2 ○ ○ ○ ○ ○ ○ ○ Impact resistance1 (Kgf·mm) 215 416 125 325 200 285 312 Impact resistance 2 ○ ○ ○ ○ ○ ○ ○ Formability ○ ○ △ ○ ○ ○ ○ overall evaluation ○ ○ ○ ○ ○ ○ ○

*1: first floor; 2: second floor

*Crystallinity of polylactic acid resin contained in it

Table 4 Embodiments of the invention 8 9 10 11 12 13 14 biodegradable laminate full board Plate thickness (μm) 300 layer structure three floors two floors three floors layer arrangement ^*1) 1/2/1 1/2 2/1/2 1/2/1 Thickness ratio 1/1/1 1/5/1 2/5 3/1/3 1/5/1 Db-Da (mass%) 10.8 7 5.9 10.8 level one Da (mass%) 1.2 5 1.2 Thickness (μm) 267 86 43 86 Crystallinity ^*2) (%) 42 30 43 46 42 42 43 polyester resin model PBS Content (mass%) 75 50 60 Second floor Db% 12 7.1 12 Thickness (μm) 34 214 257 214 Crystallinity ^*2) (%) 1.8 2.4 9.2 1.1 3.4 1 1.1 polyester resin model PBS Content (mass%) 75 50 60 evaluate Heat resistance 1(%) 0.7 1 0.9 1.2 1.4 0.9 0.8 Heat resistance 2 ○ ○ ○ ○ ○ ○ ○ Impact resistance 1(Kgf mm) 398 270 198 203 222 220 302 Impact resistance 2 ○ ○ ○ ○ ○ ○ ○ Formability ○ ○ ○ ○ ○ ○ ○ overall evaluation ○ ○ ○ ○ ○ ○ ○

*1: first floor; 2: second floor

*Crystallinity of polylactic acid resin contained in it

table 5 comparative example 1 2 3 4 5 6 biodegradable laminate full board Plate thickness (μm) 300 layer structure single layer three floors single layer three floors layer arrangement ^*1) 1 1/2/1 1 1/2/1 Thickness ratio - 1/2/1 - 1/5/1 Db-Da (mass%) - 10.8 - 4.8 level one Da (mass%) 1.2 - 1.2 7.1 Thickness (μm) 300 - 150 300 86 Crystallinity ^*2) (%) 46 5.2 - 45 43 10.1 polyester resin model none PBS Content (mass%) 0 20 40 Second floor Db% - 12 - 12 Thickness (μm) - 300 150 - 214 Crystallinity ^*2) (%) - 3.4 1.1 - 1.2 polyester resin model none PBS none PBS Content (mass%) 0 20 0 40 evaluate Heat resistance 1(%) 82.3 84.1 8.1 6.5 1.2 1.5 Heat resistance 2 x x x ○ ○ x Impact resistance 1(Kgf mm) 11 10 78 85 156 202 Impact resistance 2 x x ○ ○ ○ ○ Formability x ○ ○ x x ○ overall evaluation x x x x x x

*1: first floor; 2: second floor

*Crystallinity of polylactic acid resin contained in it

[result]

It can be seen from Table 3 to Table 5 that the heat resistance, impact resistance and formability of Examples 1 to 14 of the present invention are excellent, and the desired product can be made of any laminated board in these examples. Formed by normal molding cycle.

On the other hand, Comparative Example 1, which did not contain any biodegradable aliphatic polyester, was inferior in impact resistance and heat resistance. In addition, the formability of the product in vacuum forming is extremely poor. Like Comparative Example 1, Comparative Example 2 was also inferior in heat resistance and impact resistance. Particularly regarding heat resistance 2, the container molded from the sheet of Comparative Example 2 suffered from buckling.

Comparative Example 3 having a low content of biodegradable aliphatic polyester was poor in heat resistance. As with Comparative Example 2, with regard to heat resistance 2, the container molded from the sheet of Comparative Example 3 suffered shrinkage. Comparative Example 4 was poor in heat resistance and formability. Formability was also poor.

Comparative Example 5 showed bridging during formability evaluation. The container formed from the plate of Comparative Example 6 exhibited shrinkage during heat resistance evaluation 2.

Claims (8)

1. A biodegradable laminate comprising at least two layers, each of the at least two layers comprising a resin composition comprising 75 to 25% by mass of polylactic acid resin and 25 ~75% by mass of a polyester resin having a glass transition temperature not exceeding 0°C and a melting point higher than the glass transition temperature of said polylactic acid resin but not exceeding the melting point of said polylactic acid resin, The total amount of the polylactic acid resin and the polyester resin is by 100% by mass, wherein the D-lactic acid content Da (%) of the polylactic acid resin contained in one of the at least two layers is the same as the D-lactic acid content Db (%) of the polylactic acid resin contained in the other layer of the at least two layers Satisfy the following relationship (1): Da≤7 and Db-Da＞3 (1) The laminate is subjected to crystallization treatment. 2. A biodegradable laminate comprising at least two layers, each of the at least two layers comprising a resin composition comprising 75 to 25% by mass of polylactic acid resin and 25 ~75% by mass of polyester resin having a glass transition temperature not exceeding 0°C and a melting point not less than 80°C but not exceeding the melting point of said polylactic acid resin, said polylactic acid resin and said The total amount of polyester resin is based on 100% by mass, wherein the D-lactic acid content Da (%) of the polylactic acid resin contained in one of the at least two layers is the same as the D-lactic acid content Db (%) of the polylactic acid resin contained in the other layer of the at least two layers Satisfy the following relationship (1): Da≤7 and Db-Da＞3 (1) The laminate is subjected to crystallization treatment. 3. A biodegradable laminate comprising at least two layers, each of the at least two layers comprising a resin composition comprising 75 to 25% by mass of polylactic acid resin and 25 ~75% by mass of a polyester resin having a glass transition temperature not exceeding 0°C and a melting point higher than the glass transition temperature of said polylactic acid resin but not exceeding the melting point of said polylactic acid resin, The total amount of the polylactic acid resin and the polyester resin is by 100% by mass, wherein the D-lactic acid content Da (%) of the polylactic acid resin contained in one of the at least two layers is the same as the D-lactic acid content Db (%) of the polylactic acid resin contained in the other layer of the at least two layers Satisfy the following relationship (1): Da≤7 and Db-Da＞3 (1) The crystallinity of the polylactic acid resin contained in one of the at least two layers is not less than 20% but not greater than 100%, and the crystallinity of the polylactic acid resin contained in the other of the at least two layers is not less than 0% but not greater than 100%. less than 20%. 4. A biodegradable laminate comprising at least two layers, each of the at least two layers comprising a resin composition comprising 75 to 25% by mass of polylactic acid resin and 25 ~75% by mass of polyester resin having a glass transition temperature not exceeding 0°C and a melting point not less than 80°C but not exceeding the melting point of said polylactic acid resin, said polylactic acid resin and said The total amount of polyester resin is based on 100% by mass, wherein the D-lactic acid content Da (%) of the polylactic acid resin contained in one of the at least two layers is the same as the D-lactic acid content Db (%) of the polylactic acid resin contained in the other layer of the at least two layers Satisfy the following relationship (1): Da≤7 and Db-Da＞3 (1) The crystallinity of the polylactic acid resin contained in one of the at least two layers is not less than 20% but not greater than 100%, and the crystallinity of the polylactic acid resin contained in the other of the at least two layers is not less than 0% but not greater than 100%. less than 20%. 5. The biodegradable laminate according to any one of claims 1 to 4, wherein one of said at least two layers has a thickness of 3 to 300 microns. 6. A biodegradable laminate according to any one of claims 1 to 5, wherein one of said at least two layers comprises two outer layers and the other of said at least two layers is arranged on at least one layer between the two outer layers. 7. A product obtained by molding the biodegradable laminated sheet according to any one of claims 1 to 6 at a molding temperature not lower than the melting point of the polyester resin but lower than one of the at least two layers The melting point of the polylactic acid resin contained. 8. A method of forming an article from the biodegradable laminate according to any one of claims 1 to 6, the method comprising subjecting the laminate to a temperature not less than the melting point of the polyester resin but less than the at least two Molded at the temperature of the melting point of the polylactic acid resin contained in one of the layers.