JP2003221499A - Polylactic acid heat-shrinkable material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polylactic acid heat-shrinkable material where transparency is greatly improved in heat shrinkability and tensile strength without deteriorating and transparency of the heat-shrinkable material containing an alicyclic polyester. <P>SOLUTION: The transparency is improved by further blending polycarbodiimide to the polylactic acid heat-shrinkable material containing the polylactic polymer and the alicyclic polyester. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polylactic acid-based heat-shrinkable material. Specifically, it relates to a polylactic acid-based heat-shrinkable material containing a polylactic acid-based polymer and an aliphatic polyester other than the polylactic acid-based polymer.

[0002]

2. Description of the Related Art Conventionally, polyvinyl chloride, styrene-butadiene copolymer, polyethylene terephthalate, etc. have been known as substances constituting a heat shrinkable material used for shrink wrapping materials, shrink tie wrapping materials, shrink labels, and the like. It is also widely used in industry. However, when these heat-shrinkable materials are discarded in a natural environment, they remain without being decomposed due to their stability. In addition, the "heat shrinkable material" in this specification means a thread, a string, a film, a sheet or the like having heat shrinkability.

As the residual amount of the heat-shrinkable material increases, it causes problems such as spoiling the landscape and polluting the living environment of fish and wild birds. There has been a demand for a heat-shrinkable material composed of a decomposable polymer that does not cause these problems, and many studies and developments have been conducted in practice. Examples of the degradable polymer include polyester polymers. The heat-shrinkable material composed of a polyester polymer is decomposed into a monomer in a natural environment having moisture or water due to the inherent hydrolyzability of the polyester polymer. Furthermore, in recent years, a heat-shrinkable material made of a biodegradable polymer, which becomes a degradable product harmless by microorganisms in the soil after hydrolysis, has been earnestly desired. An example of the biodegradable polymer is polylactic acid. It is known that polylactic acid does not remain in its original form in the soil because hydrolysis naturally progresses in the soil, and after hydrolysis, it becomes a harmless degradation product by microorganisms in the soil. However, although a film or the like made of only polylactic acid is hard and excellent in transparency, it is extremely brittle and it is extremely difficult to form a heat shrinkable material as it is.

First, a conventional technique for improving the brittleness of a polylactic acid film and imparting heat shrinkability will be described. A polylactic acid-based heat-shrinkable film in which the inherent brittleness of a film made of a polylactic acid-based polymer or the like is improved by biaxially stretching a film or the like made of a polylactic-acid-based polymer, No. 187863. The polylactic acid-based heat-shrinkable film disclosed in JP-A-9-187863 has a uniaxially stretched film obtained by stretching an unstretched film in a first direction at a crystallization temperature of the uniaxially stretched film or higher. It is formed by preheating and further stretching in a direction perpendicular to the first direction. This polylactic acid-based heat-shrinkable film has the property of substantially heat-shrinking in the first direction. However, this polylactic acid-based heat-shrinkable film has a small tensile elongation at break, and it has been practically difficult to use it as a heat-shrinkable film for shrink-wrapping or shrink-binding packaging.

Further, a polylactic acid-based heat-shrinkable film having improved heat-shrinkability by mixing a crystalline polymer such as polypropylene with a polylactic acid-based polymer as a nucleating agent,
It is disclosed in Japanese Patent Laid-Open No. 2000-226571.
However, the polylactic acid-based heat-shrinkable film disclosed in JP-A-2000-226571 also has a tensile elongation at break of 1
It was about 0%, and it was practically difficult to use it as a heat-shrinkable film for shrink-wrapping or shrink-binding packaging.

A polylactic acid-based heat-shrinkable film in which the brittleness of a film made of a polylactic acid-based polymer is improved by mixing an aliphatic polyester other than polylactic acid with the polylactic-acid-based polymer is also known. It is disclosed in Japanese Patent Publication No. 2001-11214. However, it is known that the transparency of the polylactic acid-based heat-shrinkable film disclosed in Japanese Unexamined Patent Publication No. 2001-11214 deteriorates when an aliphatic polyester other than polylactic acid is mixed.

Next, when a heat shrinkable material composed of an aliphatic polyester such as a polylactic acid polymer is used as a shrink wrap or shrink label, it is necessary to control the hydrolysis inherent in the aliphatic polyester. Was also needed. A conventional technique for controlling the hydrolysis resistance of the heat shrink material mainly containing the aliphatic polyester polymer will be described below.

A method for controlling the hydrolysis rate of a biodegradable plastic such as an aliphatic polyester resin and a biodegradable plastic composition having an adjusted hydrolysis rate are disclosed in JP-A-11-80522. . The biodegradable plastic disclosed in JP-A No. 11-80522 has a hydrolysis rate adjusted by blending an aliphatic polyester or the like with a carbodiimide compound or a polycarbodiimide compound.

[0009]

In the conventional polylactic acid-based heat-shrinkable material, the transparency inherent to polylactic acid has been sacrificed in order to obtain a good heat-shrinkability and a good tensile rupture property. It was

Therefore, the present invention has been made in view of the above, and it mainly comprises a polylactic acid-based polymer and a poly-lactic acid-based polymer other than the polylactic acid-based polymer, which is a factor that deteriorates transparency. An object of the present invention is to provide a polylactic acid-based heat-shrinkable material in which transparency is greatly improved without significantly deteriorating the heat-shrinkable property and the tensile rupture property of the lactic acid-based heat-shrinkable material.

[0011]

It has been known that the hydrolysis rate of an aliphatic polyester or the like can be adjusted by blending a carbodiimide compound, but it has not been known that transparency can be improved. The inventors of the present application
The inventors have found that the transparency of a polylactic acid-based heat-shrinkable material can be improved by adding polycarbodiimide to a conventional polylactic acid-based heat-shrinkable material, and have completed the present invention.

That is, in order to solve the above-mentioned problems, the polylactic acid heat shrink material according to the present invention comprises a polylactic acid polymer and an aliphatic polyester different from the polylactic acid polymer and polycarbodiimide, and It is characterized by shrinking in at least one direction by heating. With this configuration, a polylactic acid-based polymer having excellent transparency, which is the main agent, contains a polylactic acid-based polymer as an auxiliary agent that improves the heat shrinkability and the tensile rupture property but deteriorates the transparency. Even with the material, the transparency can be improved without significantly changing the heat shrinkability and the tensile rupture property.

Since the polylactic acid polymer and other aliphatic polyesters do not inherently exhibit good compatibility, the dispersibility during mixing is poor. Polycarbodiimide is considered to act as a compatibilizing agent because it has reactivity with the hydroxyl group and carboxyl group of polylactic acid and other aliphatic polyesters. That is, when polycarbodiimide is blended, it is considered that the dispersibility of polylactic acid and other aliphatic polyester during mixing is improved, and as a result, the transparency of the formed polylactic acid heat shrink material is improved.

Furthermore, when a crystalline polymer such as a polylactic acid polymer or other aliphatic polyester is melted and then cooled, it may be crystallized or spherulites that reduce transparency may grow. Are known. However, when polycarbodiimide is blended, polycarbodiimide can act as a nucleating agent to suppress crystallization and spherulite growth, and as a result, polycarbodiimide blended polycarbodiimide can be used. The transparency of the shrink material is believed to improve.

It should be noted that the polycarbodiimide inside the polylactic acid-based heat-shrinkable material may be chemically bonded to the polylactic acid-based polymer or the aliphatic polyester, or may be mixed without being chemically bonded. . When the polycarbodiimide is dehydrogenated with the carboxyl group of the polylactic acid-based polymer or the aliphatic polyester, it is possible to improve the hydrolysis resistance of the polylactic acid-based heat shrinkable material.

When the average main chain length of the polycarbodiimide is shorter than both the average main chain length of the polylactic acid polymer and the average main chain length of the aliphatic polyester, the transparency can be surely improved. Further, a straight-chain polycarbodiimide having no branched chain or a linear shape not containing a benzene ring or the like is preferable. In the case of a polylactic acid-based heat-shrinkable material consisting only of a polylactic acid-based polymer and an aliphatic polyester, when viewed at the molecular level, there are many voids between neighboring polylactic acid-based polymers and aliphatic polyesters. It is considered that the transparency of the polylactic acid-based heat-shrinkable material containing polycarbodiimide was improved because the voids could be filled with polycarbodiimide. The "average main chain length" means the average value of the length of the polymer main chain, and is indexed by conversion from the weight average molecular weight or the number average molecular weight (average degree of polymerization).

The composition of the polylactic acid-based heat-shrinkable material which is excellent in all of the heat-shrinkability, tensile rupture property and transparency is as follows: Polycarbodiimide compounding ratio is a mixture of the polylactic acid-based polymer and the aliphatic polyester. 0.1 to 5 parts by weight with respect to 100 parts by weight, and the compounding ratio of the polylactic acid-based polymer and the aliphatic polyester in the mixed substance is 90% by weight: 10% by weight to 81% by weight: 19 It is preferably in the weight%.

When the polylactic acid polymer, the aliphatic polyester and the polycarbodiimide are uniaxially stretched and oriented in the stretching direction (uniaxial orientation), the polylactic acid heat shrink material has shrinkage anisotropy. Usually, a polylactic acid-based heat-shrinkable material in which the constituent materials are uniaxially oriented shrinks mainly in the stretching direction or only in the stretching direction by heating.

A polylactic acid-based heat-shrinkable material having a tensile elongation at break of 200% or more and a haze value of 10% or less in a direction orthogonal to the stretching direction, or heat in the stretching direction in hot water at 80 ° C. A polylactic acid-based heat-shrinkable material having a shrinkage ratio of 30% or more can be provided. Furthermore, a polylactic acid-based heat-shrinkable material having a tensile elongation at break of 200% or more, a haze value of 10%, and a heat shrinkage rate of 30% or more in hot water at 80 ° C. can be provided.

[0020]

DETAILED DESCRIPTION OF THE INVENTION The contents of the present invention will be explained,
A preferred embodiment will be described. The polylactic acid-based heat-shrinkable material according to the present invention is a heat-shrinkable material made of a resin containing polylactic acid and an aliphatic polyester other than polylactic acid and polycarbodiimide. The polylactic acid-based heat-shrinkable material according to the present invention,
The transparency is superior to the conventional heat-shrinkable material composed of polylactic acid resin and aliphatic polyester resin other than polylactic acid.

In order to secure good heat shrinkability and improve transparency, the blending amount of polycarbodiimide is 0.1 part by weight based on 100 parts by weight of the mixed substance of polylactic acid and other aliphatic polyester. % To 5% by weight is preferable. In order to reliably improve the transparency, a polycarbodiimide having a shorter average main chain length than both the average main chain length of polylactic acid and the average main chain length of the aliphatic polyester is used as the polycarbodiimide to be blended.

In order to ensure good heat shrinkability and tensile elongation at break, the mixing ratio of polylactic acid and other aliphatic polyester is (polylactic acid) :( other aliphatic polyester) = 90. It is preferable to set it so as to satisfy 10% by weight to 81% by weight: 19% by weight. The polylactic acid-based heat-shrinkable material according to the present invention may have uniaxial shrinkage or biaxial shrinkage. When used for heat-shrink binding packaging, it is often preferable to have uniaxial shrinkage. In addition, when used as a container label, the polylactic acid-based heat-shrinkable material has uniaxial shrinkability, and has high tensile rupture property and easy tear property in a direction orthogonal to the shrinking direction by heating. It is preferable.

The heat shrinkability and tensile rupture property differ depending on the manufacturing method. Generally, a stretching method is applied to impart desired heat shrinkability and tensile breakability. When the stretching method is applied, the substance that constitutes the polylactic acid-based heat-shrinkable material can be easily
It can be axially oriented. Any known technique for obtaining good heat shrinkability and good tensile elongation at break may be used. Specifically, a sheet or film extruded from a T die, an I die, a round die, or the like, or a string or a yarn is rapidly cooled with a cooling cast roll, water, compressed air, or the like to be solidified in a state close to an amorphous state, and then the roll method. A uniaxial stretching method or a biaxial stretching method using a tenter method, a tubular method, or the like can be used. In the production of a uniaxially stretched film, a tenter method is generally used to stretch the film, and
In the production of a biaxially stretched film, a roll method is applied to the longitudinal stretching and a tenter method is applied to the transverse stretching.
The axial biaxial stretching method and the simultaneous biaxial stretching method in which the tenter method is applied at the same time in the longitudinal and lateral directions are generally used.

As the polylactic acid type polymer, polylactic acid consisting of L-lactic acid and / or D-lactic acid or L-lactic acid and / or
Alternatively, a copolymer mainly containing D-lactic acid as a constituent or a mixture thereof can be exemplified. Here, polylactic acid includes poly L-lactic acid whose structural unit is L-lactic acid, poly D-lactic acid whose structural unit is D-lactic acid, and poly DL which is a copolymer of L-lactic acid and D-lactic acid. -Includes lactic acid.

In producing the polylactic acid-based polymer, the polylactic acid-based polymer can be produced by applying a known method such as a condensation polymerization method or a ring-opening polymerization method. Specifically, in the polycondensation method, polylactic acid can be produced by directly dehydrating and polycondensing L-lactic acid, D-lactic acid or a mixture thereof. In addition, in the ring-opening polymerization method, polylactic acid can be produced by subjecting lactic acid lactide, which is a cyclic dimer of lactic acid, to ring-opening polymerization in the presence of a predetermined catalyst, if necessary, using a polymerization modifier or the like. Lactic acid lactide includes L-lactide which is a dimer of L-lactic acid, D-lactide which is a dimer of D-lactic acid, and LD-lactide which is a dimer of L-lactic acid and D-lactic acid. Therefore, any one or more of these three lactic acid lactides can be used to produce a desired polylactic acid.

As the aliphatic polyester, an aliphatic polyester obtained by condensing an aliphatic glycol and an aliphatic polybasic acid (or an anhydride thereof), or an aliphatic polyester obtained by ring-opening polymerization of a cyclic lactone is used. Examples thereof include polyesters, synthetic aliphatic polyesters, and aliphatic polyesters biosynthesized in cells. The most transparent aliphatic polyester is obtained by condensing an aliphatic glycol and an aliphatic polybasic acid (or an anhydride thereof).
When this aliphatic polyester having excellent transparency is used, an extremely highly transparent polylactic acid heat shrink material can be produced.

Aliphatic glycol / polybasic acid polyester resin obtained by reacting an aliphatic glycol with an aliphatic polybasic acid (or an anhydride thereof) in the presence of a catalyst, or a small amount of a coupling agent if necessary. Examples of the high molecular weight aliphatic glycol / polybasic acid polyester resin reacted using Examples of the aliphatic glycols include ethylene glycol, 1,4-butanediol, 1,6-hexanediol, decamethylene glycol, neopentyl glycol, 1,4-cyclohexanedimethanol and the like. In addition, ethylene oxide can also be used as the aliphatic glycols.
Further, it may be an aliphatic glycol / polybasic acid polyester resin synthesized by combining plural kinds of glycols. On the other hand, as the aliphatic polybasic acid and its acid anhydride,
Commercially available products such as succinic acid, adipic acid, suberic acid, sebacic acid, dodecanoic acid, succinic anhydride and adipic anhydride can be used. Further, it may be an aliphatic glycol / polybasic acid polyester resin synthesized by using plural kinds of polybasic acids and / or their acid anhydrides in combination.

In the above description, the aliphatic polyester consisting only of the aliphatic glycols and the aliphatic polybasic acid has been explained, but a small amount of other components such as aromatic glycols and trimellitic anhydride or pyromyl anhydride. An aromatic polybasic acid such as meritic acid can also be used in combination. However, it should be noted that the introduction of these aromatic components deteriorates the biodegradability of the polylactic acid heat shrink material. Also,
It should be noted that the presence of an aromatic component lowers the compatibility and deteriorates the transparency of the polylactic acid heat shrink material.

As the polycarbodiimide, those produced by various methods can be used, but basically, the conventional polycarbodiimide production method (US Pat.
No. 41956, Japanese Patent Publication No. 47-33279,
J. 0 rg. Chem. 28, 2069-2075
(1963), Chemical Review l98.
1, Vol. 81 No. 4, p619-621) can be used.

As the organic diisocyanate which is a raw material for producing polycarbodiimide, for example, aromatic diisocyanate, aliphatic diisocyanate, alicyclic diisocyanate and mixtures thereof can be mentioned, and specifically, 1,5- Naphthalene diisocyanate, 4,
4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,
6-tolylene diisocyanate, a mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, hexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4 '. -Diisocyanate, methylcyclohexane diisocyanate, tetramethylxylylene diisocyanate, 2,6-diisopropylphenyl isocyanate, 1,3,5-triisopropylbenzene-
2,4-diisocyanate can be exemplified.

As long as the effects of the present invention are exhibited, the polylactic acid-based heat-shrinkable material according to the present invention further includes a heat stabilizer, a light stabilizer, a lubricant, a plasticizer, an inorganic filler, a deodorant,
It should be noted that it is understood to include a polylactic acid-based heat shrink material having an additive such as an antistatic agent. Further, the purpose of producing a heat-shrinkable material having high transparency is not only to simply pursue transparency, but also to provide a colored heat-shrinkable material having light transparency and high color purity. Therefore, although the transparency is deteriorated by adding a colorant, a pigment, etc., it is understood that the polylactic acid heat shrink material according to the present invention includes a polylactic acid heat shrink material having a colorant, a pigment, etc. Be careful to do so.

The contents of the present invention will be specifically described below based on Examples and Comparative Examples. The physical properties of the resin films produced in each of the examples and the comparative examples are collectively shown in Table 1.

First, a method of measuring physical property values (evaluation method) will be described. The haze value and the tensile elongation at break are JIS K-6782 and JIS K-6732, respectively.
The measurement and evaluation were performed according to the No. Here, the haze value is a physical property value that gives an index of transparency, the smaller the haze value is, the more excellent the transparency is, and the tensile breaking elongation is a physical property value that gives an index of tensile breaking property. The larger the value, the better the tensile rupture property. The heat shrinkage rate was measured and evaluated by a change in dimension when a square test piece having a side of 10 cm was immersed in warm water of 80 ° C. for 10 seconds.

Example 1 90% by weight of polylactic acid (H100E manufactured by Mitsui Chemicals, Inc.), aliphatic polyester (Bionole # 3003 manufactured by Showa High Polymer Co., Ltd.) 10
1 part by weight of a polycarbodiimide resin (Carbodilite HMV-8CA, manufactured by Nisshinbo Co., Ltd.) was added to 100 parts by weight of the mixed resin consisting of 10% by weight, and then sufficiently dehumidified and dried. Dehumidifying and drying the resin, cylinder temperature 190 ℃
After kneading in a twin-screw extruder under the above environment, it is extruded into a strand shape. After cutting the extruded resin to form pellets having a diameter of 3 mmφ and a thickness of 3 mm,
It was dehumidified and dried by a dehumidifying dryer. The pellets that have been dehumidified and dried are melt-kneaded and then extruded onto a cooling roll to have a thickness of 30.
A 0 μm resin sheet was formed. In forming the resin sheet, the cylinder temperature is 190 ° C and the die temperature is 1
A T-die extruder set at 85 ° C was used. The surface temperature of the cooling roll was set to 35 ° C. Subsequently, after preheating to 90 ° C. in a tenter, the resin sheet heated to 80 ° C. to 70 ° C. was stretched 5 times in the direction orthogonal to the extrusion direction to produce a resin film having a thickness of 60 μm. Immediately after stretching, the resin film was heat-fixed at 70 ° C. for a certain period of time.

The physical properties of the resin film according to this example are as follows:
The haze value was 5%, the tensile elongation at break was 300%, and the shrinkage ratio was 40%. As can be seen from Comparative Example 2 below, the resin film having a haze value of 5% produced without blending the polycarbodiimide resin has a tensile elongation at break of 10% or less and cannot be put to practical use.

Further, when this example is compared with the following comparative example 3, it can be seen that the heat shrinkage and the tensile elongation at break are substantially the same, but the transparency is remarkably improved. This means that by blending the polycarbodiimide resin, the blending amount of the aliphatic polyester for improving the heat shrinkability and the tensile breakability can be reduced. The remarkable improvement in transparency in this case is due to the improvement in transparency due to the addition of polycarbodiimide and the improvement in transparency due to the reduction of the amount of the aliphatic polyester that deteriorates the transparency.

Example 2 The resin film according to this example was produced by the same manufacturing method as in Example 1 except that the compounding ratio of the polylactic acid and the aliphatic polyester of the mixed resin in Example 1 was changed. Was manufactured. The compounding ratio of polylactic acid and aliphatic polyester in the resin film according to this example was 85% by weight of polylactic acid: 15% by weight of aliphatic polyester. It should be noted that the resin film according to this example contains 1 part by weight of the polycarbodiimide resin with respect to 100 parts by weight of the mixed resin of polylactic acid and the aliphatic polyester.

The physical properties of the resin film according to this example are
The haze value was 7%, the tensile elongation at break was 400%, and the shrinkage ratio was 42%. It can be seen that the resin film according to this example has a smaller haze value than the resin film according to Comparative Example 3 below, although the tensile elongation at break and the shrinkage ratio are not significantly changed. That is, the transparency of the resin film is greatly improved.

Example 3 The resin film according to this example was produced by the same manufacturing method as in Example 1 except that the compounding ratio of the polylactic acid and the aliphatic polyester of the mixed resin in Example 1 was changed. Was manufactured. The compounding ratio of the polylactic acid and the aliphatic polyester in the resin film according to this example is 82% by weight of polylactic acid: 18% by weight of aliphatic polyester. It should be noted that the resin film according to this example contains 1 part by weight of the polycarbodiimide resin with respect to 100 parts by weight of the mixed resin of polylactic acid and the aliphatic polyester.

The physical properties of the resin film according to this example are as follows:
The haze value was 10%, the tensile elongation at break was 450%, and the shrinkage ratio was 40%. It can be seen that the resin sheet according to this example has a smaller haze value than the resin film according to Comparative Example 4 below, although the tensile elongation at break and the shrinkage ratio do not change significantly.

Comparative Example 1 A resin film according to this example was manufactured by the same manufacturing method as in Example 1 except that a resin consisting of polylactic acid alone was used instead of the mixed resin in Example 1 above. . It should be noted that the resin film according to this example contains 1 part by weight of polycarbodiimide resin with respect to 100 parts by weight of the resin made of polylactic acid.

Regarding the physical properties of the resin sheet according to this comparative example, the haze value was 0.5%, the tensile elongation at break was 10% or less, and the shrinkage ratio was 43%. As can be seen from this comparative example and the following comparative examples 2 to 5, the tensile elongation at break can be increased by incorporating the aliphatic polyester. It is also understood that the tensile elongation at break and the haze value increase as the blending ratio of the aliphatic polyester in the mixed resin increases. The shrinkage rate of the resin film according to each comparative example has a small dependency on the compounding rate of the aliphatic polyester in the mixed resin, and is a substantially constant value.

(Comparative Example 2) The compounding ratio of the polylactic acid and the aliphatic polyester of the mixed resin in Example 1 was 95.
% By weight: A resin film according to this example was produced by the same production method as in Example 1 except that the content was 5% by weight and no polycarbodiimide resin was added. Regarding the physical property value of the resin film according to this comparative example, the haze value is 5
%, The tensile elongation at break was 10% or less, and the shrinkage rate was 41%.

Comparative Example 3 A resin film according to this example was produced in the same manner as in Example 2 except that the polycarbodiimide resin was not added. Regarding the physical properties of the resin film according to this example, the haze value was 15%, the tensile elongation at break was 350%, and the shrinkage rate was 42%.

Comparative Example 4 A resin film according to this example was produced in the same manner as in Example 3 except that the polycarbodiimide resin was not added. Regarding the physical properties of the resin film according to this example, the haze value was 22%, the tensile elongation at break was 410%, and the shrinkage rate was 43%.

(Comparative Example 5) The compounding ratio of the polylactic acid and the aliphatic polyester of the mixed resin in Example 1 was 75.
% By weight: A resin film according to this example was produced by the same production method as in Example 1 except that the amount was 25% by weight and no polycarbodiimide resin was added.
Regarding the physical property values of the resin film according to this example, the haze value is 2
7%, tensile elongation at break was 520%, and shrinkage was 40%.

[Table 1]

[0047]

As described above, according to the present invention, the transparency of the polylactic acid-based heat-shrinkable material containing the polylactic acid-based polymer and the aliphatic polyester other than the polylactic acid-based polymer that deteriorates the transparency. Can be improved by adding polycarbodiimide. Moreover, when the aliphatic polyester has biodegradability, the polylactic acid-based heat-shrinkable material according to the present invention is an extremely good biodegradable heat-shrinkable material.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08L 79:00) C08L 79:00 Z B29K 67:00 B29K 67:00 479: 00 479: 00 (72) Inventor Tomohisa Okuda 163 Morikawara-cho, Moriyama-shi, Shiga Gunshi stock company Moriyama factory (72) Inventor Hideo Hayashi 163 Morikawara-cho, Moriyama city Shiga Gunze stock company F-term (reference) 4F071 AA43 AA44 AA58 AF15Y AF30Y AF61 AH04 BB06 BB07 BC01 4F210 AA24 AA40 AE01 AG01 AH54 AR12 RA03 RC02 RG02 RG04 RG43 4J002 CF032 CF092 CF181 CM053 GG02

Claims (6)

[Claims] 1. A heat-shrinkable material comprising a polylactic acid-based polymer, an aliphatic polyester different from the polylactic acid-based polymer, and a polycarbodiimide, which shrinks in at least one direction by heating. 2. The heat-shrinkable material according to claim 1, wherein the average main chain length of the polycarbodiimide is both the average main chain length of the polylactic acid polymer and the average main chain length of the aliphatic polyester. Heat shrink material characterized by being shorter than. 3. The heat-shrinkable material according to claim 2, wherein the mixing ratio of the polycarbodiimide is the mixed substance 1 composed of the polylactic acid-based polymer and the aliphatic polyester.
0.1 to 5 parts by weight with respect to 00 parts by weight, and the compounding ratio of the polylactic acid-based polymer and the aliphatic polyester in the mixed substance is 90% by weight: 10% by weight.
~ 81% by weight: 19% by weight, a heat-shrinkable material. 4. The heat-shrinkable material according to claim 3, wherein the polylactic acid polymer, the aliphatic polyester, and the polycarbodiimide are oriented in a stretching direction by uniaxial stretching. Heat shrink material. 5. The heat-shrinkable material according to claim 4, wherein the tensile elongation at break is 2 in a direction orthogonal to the stretching direction.
A heat-shrinkable material having a haze value of 100% or more and a haze value of 10% or less. 6. The heat-shrinkable material according to claim 4, wherein the shrinkage ratio in the stretching direction in hot water of 80 ° C. is 30.
% Or more is a heat-shrinkable material.