JPH06340753A - Degradable card - Google Patents

Abstract

PURPOSE:To obtain a card composed of a thermoplastic polymer composition consisting mainly of a specific copolymer, degradable under natural circumference and having sufficient strength and durability and useful for telephone card, etc. CONSTITUTION:The card is composed of a thermoplastic polymer composition consisting mainly of a polylactic acid or a copolymer of lactic acid (preferably L-lactic acid, D-lactic acid or its mixture) and the other hydroxycarboxylic acid (preferably glycolic acid or 6-hydroxycaproic acid).

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to degradable cards.
More specifically, the present invention relates to a degradable card which is composed of a thermoplastic polymer composition mainly containing lactic acid polymer and has degradability in a natural environment.

[0002]

2. Description of the Related Art In recent years, various cards such as telephone cards for making telephone calls, commuter passes and orange cards for boarding trains, and prepaid cards for shopping at convenience stores have been used. . In addition, it has become a common era that everyone has many cash cards, credit cards, identification cards, membership cards, etc. depending on the company. The more cards I have, the more cards I get useless. Heretofore, as these cards, those made of resin such as polyethylene terephthalate or polyvinyl chloride or paper coated with resins have been used. Among them, the card made of resin was incinerated together with other garbage to be effectively used as a calorie source, or was disposed of in landfill.

However, when the resin is incinerated, the combustion heat is higher and the calories are higher than those of other wastes, so that the combustion furnace must be designed to withstand the heat load, and it is economical. Burden is heavy. In addition, polyvinyl chloride has a problem that it produces toxic hydrogen chloride during combustion. In the case of landfilling the resin, there is a problem that the resin such as polyethylene terephthalate and polyvinyl chloride is hardly decomposed in the soil and remains without being decomposed. Cards coated with resin on paper are
Since there is no degradability in an alkaline solution for recovering pulp from paper, it was necessary to take out and separate the paper inside during the pulp recovery process.

In Japanese Unexamined Patent Publication (Kokai) No. 5-42786, a random copolymerized polyester of 3-hydroxybutyrate and 3-hydroxyvalerate, which is a biodegradable resin, a polyester mainly composed of 3-hydroxybutyrate, or polycaprolactone is used. Cards are molded with a mixture of starch. However, the card formed of 3-hydroxybutyrate or the like has a weak strength and is not satisfactory as a card which requires repeated use. Also,
Cards molded from a resin with starch added were not suitable for use at all, such as mold growing on them and mice scratching when left on them.

On the other hand, polylactic acid or a copolymer of lactic acid and other hydroxycarboxylic acid (hereinafter abbreviated as lactic acid-based polymer) has been developed as a thermoplastic resin biodegradable polymer. These polymers are 100% biodegradable within a few months to a year within the body of an animal, and when placed in soil or seawater, they begin to decompose within a few weeks in a moist environment and within one to several years. Furthermore, the decomposition products have the property that they become lactic acid, carbon dioxide, and water that are harmless to the human body. However, a card using the above-mentioned degradable lactic acid-based polymer has not been developed, and at present there is no excellent card that is easily decomposed in a natural environment and has appropriate strength and durability.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a card which can be decomposed in a natural environment and has sufficient strength and durability.

[0007]

The present inventors have completed the present invention by finding that a degradable card can be obtained by using a resin containing a lactic acid-based polymer as a main component. That is, the present invention is a degradable card composed of a thermoplastic polymer composition containing a polylactic acid-based polymer as a main component.

The polymer used in the present invention is mainly composed of a polylactic acid-based polymer, and other hydroxycarboxylic acids include glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 4-hydroxyvaleric acid and 5
-Hydroxyvaleric acid, 6-hydroxycaproic acid, etc. are used. The polylactic acid-based polymer is formed by dehydration polycondensation of lactic acid or lactic acid and other hydroxycarboxylic acid directly, or lactide which is a cyclic dimer of lactic acid, or a cyclic ester intermediate of hydroxycarboxylic acid, such as glycolic acid
Glycolide (GLD) which is a monomer and ε-caprolactone (C which is a cyclic ester of 6-hydroxycaproic acid
A ring-opening polymerized product may be used by appropriately using a copolymerizable monomer such as L). When directly condensing, lactic acid or lactic acid and other hydroxycarboxylic acid are azeotropically dehydrated and condensed, preferably in the presence of an organic solvent, particularly a phenyl ether solvent,
Particularly preferably, water is removed from the solvent distilled by azeotropic distillation and the substantially anhydrous solvent is returned to the reaction system to carry out polymerization to obtain a high molecular weight polylactic acid having a strength suitable for the present invention. To be Lactic acid as a raw material is L-
It may be lactic acid or D-lactic acid or a mixture thereof.

For the lactic acid polymer, a generally known thermoplastic polymer or plasticizer, and various modifiers are used,
A thermoplastic polymer composition. As the known thermoplastic polymer, degradable substances such as polyglycolic acid and poly ε-caprolactam are preferable. The proportion of the lactic acid-based polymer in the thermoplastic polymer composition may be any proportion depending on the desired degradability, but is generally 50%.
The above is preferable. In addition, all known kneading techniques can be applied to the production of the thermoplastic polymer composition, but the composition is used in the form of pellets, rods, powders, or the like. The average molecular weight of the polymer is not particularly limited. Usually, about 50,000 to 1,000,000 objects are used for applications requiring strength. When the molecular weight is 50,000 or less, the strength is low for forming a film or a molded product. If the molecular weight is higher than 1,000,000, the viscosity in the molten state will be high and the moldability will be poor.

The method for molding the polymer is not particularly limited, but it is usually carried out by extrusion sheet molding, press molding or the like, and it may be stretched if necessary. The molding conditions are appropriately determined depending on the molding machine, the type of polymer, etc., and some of them will be exemplified. Extruder: 40mmφ, 50rp
m Extrusion temperature: 190 to 220 ° C. T die: Slit 0.2 mm,
Width 150 mm Stretching temperature: 50 to 150 ° C. Stretching ratio: 3 to 8 In the card, the magnetic recording layer and the heat sensitive recording layer are provided on the same side of the non-magnetic substrate, and as shown in FIG. First, a magnetic recording layer 4 made of a magnetic coating film is formed on a magnetic body 5, and an underlayer 3, a heat-sensitive recording layer 2 made of a thin film of a low melting point nonmagnetic metal, and a protective layer 1 are sequentially laminated on the magnetic recording layer 4. It may be obtained by any method. Any method may be used for recording on the card, but magnetic recording,
Methods such as electronic recording by LSI and optical recording are known. Hereinafter, the present invention will be specifically described with reference to examples.

[0011]

【Example】

Production Example 1 216 g (1.5 mol) of L-lactide, 0.01% by weight of tin octoate, and 0.03 lauryl alcohol
Polymerization% was sealed in a thick cylindrical stainless steel polymerization container equipped with a stirrer, deaerated under vacuum for 2 hours, and then replaced with nitrogen gas. This mixture is stirred under a nitrogen atmosphere for 200
Heated at ° C for 3 hours. While maintaining the temperature as it was, the inside of the reaction vessel was depressurized to 3 mmHg by gradually degassing with a vacuum pump through an exhaust pipe and a glass receiver. One hour after the start of degassing, the distillation of the monomer and low-molecular-weight volatile matter disappeared, so the interior of the container was replaced with nitrogen, and the polymer was extracted from the lower part of the container in the form of a string and pelletized to obtain poly L-lactic acid. The molecular weight of this polymer was about 100,000.

Production Example 2 10.0 kg of 90% L-lactic acid was added at 150 ° C./50 mmHg.
After distilling water while stirring for 3 hours, 6.2 g of tin powder
Was added, and the mixture was stirred at 150 ° C./30 mmHg for 2 hours for oligomerization. 28.8 g of tin powder and 21.1 kg of diphenyl ether were added to this oligomer, and the temperature was changed to 150 ° C / 3.
An azeotropic dehydration reaction was performed at 5 mmHg, the distilled water and the solvent were separated by a water separator, and only the solvent was returned to the reactor. After 2 hours, the organic solvent returned to the reactor was passed through a column packed with 4.6 kg of molecular sieve 3A and then returned to the reactor to carry out a reaction at 150 ° C./35 mmHg for 40 hours, and an average molecular weight Mw = 100. 1,000 polylactic acid was obtained. 44 kg of dehydrated diphenyl ether was added to this solution to dilute it, then cooled to 40 ° C. and the precipitated crystals were filtered and dried at 60 ° C./50 mmHg to obtain 6.1 kg of polylactic acid powder (yield 85%). . The powder was treated with a pelletizer to pelletize polylactic acid. The molecular weight of this polymer was about 100,000.

Production Example 3 Poly DL-lactic acid was obtained from 98% DL-lactic acid 9.2 kg in the same manner as in Production Example 2 and pelletized. The average molecular weight of this polymer was about 100,000.

Production Example 4 L-lactic acid was replaced with 5.0 kg of L-lactic acid and 5.0 kg of glycolic acid instead of 10.0 kg of L-lactic acid in the same manner as in Production Example 2.
A copolymer of lactic acid and glycolic acid was obtained and pelletized.
The average molecular weight of this polymer was about 100,000. Hereinafter, using these polymers, the card shown in the example was manufactured as a prototype. The average molecular weight (weight average molecular weight) of the polymer was measured by gel permeation chromatography using polystyrene as a standard under the following conditions.

Equipment: Shimadzu LC-10AD Detector: Shimadzu RID-6A Column: Hitachi Chemical GL-S350DT-5, GL-S3
70DT-5 Solvent: Chloroform Concentration: 1% Injection volume: 20 μl Flow rate: 1.0 ml / min

The physical characteristics of the card were tested under the following conditions. Test site conditions: Test sites are unless otherwise specified.
Room temperature and normal humidity (Temperature 20 ± 1 specified in JIS Z8703
5 ° C., humidity 65 ± 20%). Specimen: Specimen is taken from the sheet-shaped test before cutting into a card and having the specified dimensions. However, the product card itself is used unless otherwise specified. Tensile Strength: The tensile strength test is based on JIS C 2318, 6.3.3 (tensile strength and elongation). Impact strength: In the impact strength test, the card is placed on a solid horizontal plate, a 500 g steel ball is dropped from the height of 30 cm to the center of the card, and the card is checked for cracks or cracks. Folding endurance: The folding endurance test is based on JIS P8115. Stiffness: JIS P 8125 is applied mutatis mutandis to the stiffness test.

Mold resistance: After drying a sample (50 × 50 mm) in a desiccator, its weight was measured, a test piece was placed on a sterilized and solidified medium, and a spore suspension of a test bacterium was spray-inoculated to give 30 Incubate in a constant temperature bath at ℃ and observe the growth of mold. After 4 weeks, the test piece is washed under running water, water is taken out with a filter paper, dried in a desiccator, and weight loss is measured. Decomposability in compost: A sample is embedded in compost at a temperature of 35 ° C. and a humidity of 30%, and a decomposability test is performed to examine changes after 2 months.

Example 1 The polymer of Production Example 1 was pressed with a press molding machine at a temperature of 200 ° C. and a pressure of 30 tons for 5 minutes, and then cooled at 40 ° C. for 5 minutes to obtain a transparent sheet having a thickness of 188 μm. .
A magnetic coating film is applied on the obtained sheet and dried to give a thickness of 15
A magnetic recording layer composed of a magnetic coating film of μm was formed. next,
An underlying layer having a thickness of 2 μm was formed thereon, and a thermosensitive recording layer, an intermediate layer and a protective layer were sequentially formed on the underlayer to prepare a thermosensitive recording medium. The tensile strength of this card is 68 N / mm ²
Met. The impact strength test passed, the folding endurance was 200 times or more, and the stiffness was 1.76 mN · m or more. In the mold resistance test, mold growth was not observed after 4 weeks. Further, in the composting decomposition test, the shape was easily broken by external force after 2 months.

Example 2 A sheet having a thickness of 188 μm was obtained from the polymer of Production Example 2 in the same manner as in Example 1 in place of the polymer of Production Example 1, and a thermal recording medium was prepared in the same manner as in Example 1. Created. The tensile strength of this card was 68 N / mm ² .
The impact strength test passed, the folding endurance was 200 times or more, and the stiffness was 1.76 mN · m or more. In the mold resistance test, mold growth was not observed after 4 weeks. Also,
In the composting decomposition test, the shape was easily destroyed by external force after 2 months.

Example 3 A sheet having a thickness of 188 μm was obtained from the polymer of Production Example 3 in the same manner as in Example 1 instead of the polymer of Production Example 1, and a thermal recording medium was prepared in the same manner as in Example 1. Created. The tensile strength of this card was 60 N / mm ² .
The impact strength test passed, the folding endurance was 200 times or more, and the stiffness was 1.76 mN · m or more. In the mold resistance test, mold growth was not observed after 4 weeks. Also,
In the composting decomposition test, the shape was easily destroyed by external force after 2 months.

Example 4 A sheet having a thickness of 188 μm was obtained from the polymer of Production Example 4 in the same manner as in Example 1 instead of the polymer of Production Example 1, and a thermal recording medium was prepared in the same manner as in Example 1. Created. The tensile strength of this card was 52 N / mm ² .
The impact strength test passed, the folding endurance was 200 times or more, and the stiffness was 1.76 mN · m or more. In the mold resistance test, mold growth was not observed after 4 weeks. Also,
In the composting decomposition test, the shape was easily destroyed by external force after 2 months.

Example 5 A polylactic acid sheet similar to that of Example 1 was recrystallized at 80 ° C. for 1 hour to obtain a sheet, and a thermal recording medium was prepared in the same manner as in Example 1. The tensile strength of this card is 78
It was N / mm ² . The impact strength test passed, the folding endurance was 200 times or more, and the stiffness was 1.76 mN · m or more. In the mold resistance test, mold growth was not observed after 4 weeks. Further, in the composting decomposition test, the shape was easily broken by external force after 2 months.

Comparative Example 1 Instead of the polymer of Production Example 1, Biopol (manufactured by ICI), which is a random copolymerized polyester of 3-hydroxybutyrate and 3-hydroxyvalerate, was used in the same manner as in Example 1. A 188 μm-thick sheet was obtained, and a thermal recording medium was prepared in the same manner as in Example 1. This card has a low tensile strength of 24 N / mm ² , passed the impact strength test, a folding endurance of 200 times or more, and a stiffness of 0.7.
It was a low value of 3 mN · m. 4 in mold resistance test
After a week, mold grew on more than 2/3 of the area of the curd. In the compost-degrading test, it disappeared after 2 months.

Comparative Example 2 A sheet having a thickness of 188 μm was obtained in the same manner as in Example 1 from Matterby (manufactured by Novamont) containing starch and modified polyvinyl alcohol as main components instead of the polymer of Production Example 1. A thermosensitive recording medium was prepared in the same manner as in method 1. This card has a low tensile strength of 22 N / mm ² , passed the impact strength test, and has a folding strength of 200 times or more,
The stiffness was a low value of 0.53 mN · m. In the mold resistance test, after 4 weeks, mold grew on the area of 2/3 or more of the curd. In the compost-degrading test, it disappeared after 2 months.

[0025]

Industrial Applicability The degradable card made of a thermoplastic resin containing lactic acid-based polymer as a main component according to the present invention has sufficient strength and durability, and is further buried in the ground as waste or dumped in the sea or river. When decomposed, it decomposes in the natural environment within a relatively short period of time like natural products such as paper and wood.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a card.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical display location C08L 67:04 (72) Inventor Kazuhiko Suzuki 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemical Co., Ltd. In the company

Claims (3)

[Claims] 1. A degradable card comprising a thermoplastic polymer composition containing polylactic acid or a copolymer of lactic acid and another hydroxycarboxylic acid as a main component. 2. The degradable card according to claim 1, wherein the lactic acid is L-lactic acid, D-lactic acid or a mixture thereof. 3. The hydroxycarboxylic acid is glycolic acid,
Alternatively, the degradable card according to claim 1, which is 6-hydroxycaproic acid.