JP3290504B2 - Degradable card - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a degradable card.
More specifically, the present invention relates to a degradable card made of a thermoplastic polymer composition mainly composed of a lactic acid polymer and degradable in a natural environment.

[0002]

2. Description of the Related Art In recent years, various cards such as telephone cards for making telephone calls, regular tickets and orange cards for getting on trains, and prepaid cards for shopping at convenience stores have been used. . In addition, it has become commonplace to have many cash cards, credit cards, identification cards, and membership cards for every company. The more cards you have, the more cards you don't need. Heretofore, cards made of resin such as polyethylene terephthalate and polyvinyl chloride or paper coated with resins have been used as these cards. Among them, cards manufactured from resin have been incinerated with other garbage, and have been effectively used as a calorie source, or have been landfilled.

However, when incinerating a resin, the combustion furnace has a higher heat of combustion and a higher calorie than other garbage, so that a furnace designed to withstand the heat load must be used. Burden is large. Further, polyvinyl chloride has a problem that toxic hydrogen chloride is generated during combustion. When the resin is landfilled, there is a problem that a resin such as polyethylene terephthalate or polyvinyl chloride is hardly decomposed in soil and therefore remains without being decomposed. Card coated with resin on paper,
Since there is no decomposability in an alkaline solution for recovering pulp from paper, it was necessary to take out the paper inside and separate it during the pulp recovery process.

JP-A-5-42786 discloses a random copolymerized polyester of 3-hydroxybutyrate and 3-hydroxyvalerate which is a biodegradable resin, a polyester mainly composed of 3-hydroxybutyrate, or polycaprolactone. The card is molded from a mixture of starch. However, cards molded with 3-hydroxybutyrate or the like have low strength and are not satisfactory as cards requiring repeated use. Also,
Cards molded from a resin to which starch was added were not usable at all, such as mold growing or the mouse biting if left behind.

On the other hand, polylactic acid or a copolymer of lactic acid and another hydroxycarboxylic acid (hereinafter abbreviated as lactic acid-based polymer) has been developed as a biodegradable polymer of a thermoplastic resin. These polymers are 100% biodegradable in the body of animals in months to one year, and when placed in soil or seawater, begin to degrade in weeks in moist environments and disappear in one to several years. Furthermore, the decomposition product has the property of becoming lactic acid, carbon dioxide, and water that are harmless to the human body. However, no card using the degradable lactic acid-based polymer has been developed, and at present, there is no excellent card that easily decomposes in a natural environment and has appropriate strength and durability.

[0006]

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

[0007]

Means for Solving the Problems The present inventors have found that a degradable card can be obtained by using a resin containing a lactic acid-based polymer as a main component, and have completed the present invention. That is, the present invention is a degradable card comprising a thermoplastic polymer composition containing a lactic acid-based polymer as a main component.

The polymer used in the present invention is a lactic acid-based polymer.
Rimer is used as a main component, and other hydroxycarboxylic acids include glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 4-hydroxyvaleric acid, and 5-hydroxyvaleric acid.
Hydroxyvaleric acid, 6-hydroxycaproic acid and the like are used. The lactic acid-based polymer is a dehydration polycondensation directly from lactic acid or lactic acid and another hydroxycarboxylic acid, or a cyclic dimer of lactic acid or a cyclic ester intermediate of hydroxycarboxylic acid, for example, a dimer of glycolic acid. A product obtained by ring-opening polymerization using a copolymerizable monomer such as glycolide (GLD) or ε-caprolactone (CL), which is a cyclic ester of 6-hydroxycaproic acid, may be used. If direct condensation is preferably an organic solvent lactic acid or lactic acid and other <br/> hydrin b Kishikarubon acid, in particular azeotropic dehydration condensation in the presence of a phenyl ether solvent, especially preferably azeotropically distilled By removing the water from the solvent and polymerizing by a method of returning the substantially anhydrous solvent to the reaction system, a high molecular weight polymer having a strength suitable for the present invention is obtained.
A lactic acid-based polymer is obtained. Lactic acid as a raw material is L-
Either lactic acid or D-lactic acid or a mixture thereof may be used.

The lactic acid-based polymer is made into a thermoplastic polymer composition by using a generally known thermoplastic polymer or a plasticizer and various modifiers. As the known thermoplastic polymer, a decomposable material such as polyglycolic acid and polyε-caprolactam is preferable. The proportion of the lactic acid-based polymer in the thermoplastic polymer composition may be an arbitrary proportion depending on the intended degradability, but is generally 5%.
0% or more is preferable. For the production of the thermoplastic polymer composition, all known kneading techniques can be applied, but the composition is used in the form of pellets, rods, powders and the like. The weight average molecular weight (Mw) of the polymer is not particularly limited. For applications requiring strength, about 50,000 to 1,000,000 are usually used. At a weight average molecular weight (Mw) of 50,000 or less, the strength is low for forming a film or a molded product. On the other hand, when the weight average molecular weight (Mw) is higher than 1,000,000, the viscosity in the molten state is high and the moldability is poor.

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

[0011]

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

Production Example 2 10.0 kg of 90% L-lactic acid at 150 ° C./50 mmHg
After distilling water while stirring for 3 hours, 6.2 g of tin powder was obtained.
Was added, and the mixture was further stirred at 150 ° C./30 mmHg for 2 hours to oligomerize. To this oligomer were added 28.8 g of tin powder and 21.1 kg of diphenyl ether, and the mixture was added at 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 to be returned to the reactor was passed through a column filled with 4.6 kg of molecular sieve 3A, and then returned to the reactor. The reaction was carried out at 150 ° C./35 mmHg for 40 hours to obtain a weight average molecular weight ( Mw). ) = 100,000 poly
L- lactic acid was obtained. 44 kg of dehydrated diphenyl ether was added to this solution for dilution, and then cooled to 40 ° C., and the precipitated crystals were filtered and dried at 60 ° C./50 mmHg.
6.1 kg (85% yield) of poly L- lactic acid powder was obtained. This powder is processed by a pelletizer and pelletized, and poly -L-
Lactic acid was obtained. The molecular weight of this polymer was about 100,000.

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

Production Example 4 L-lactic acid was produced in the same manner as in Production Example 2 except that 10.0 kg of L-lactic acid was changed to 5.0 kg of L-lactic acid and 5.0 kg of glycolic acid.
A copolymer of lactic acid and glycolic acid was obtained and pelletized.
The weight average molecular weight (Mw) of this polymer was about 100,000. Hereinafter, using these polymers, the cards shown in Examples were prototyped. The weight average molecular weight (M
w) was measured by gel permeation chromatography using polystyrene as a standard under the following conditions.

Apparatus: 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: Unless otherwise specified, the test site
Normal temperature and normal humidity (temperature 20 ± 1) specified in JIS Z8703
5 ° C., humidity 65 ± 20%). Specimen: Specimens shall be of specified dimensions from a sheet test before cutting into cards. However, unless otherwise specified, it shall be the product card itself. Tensile strength: The tensile strength test is based on 6.3.3 (tensile strength and elongation) of JIS C 2318. Impact Strength: In the impact strength test, a card is placed on a firm horizontal plate, a 500 g steel ball is dropped from a height of 30 cm to the center of the card, and the card is checked for cracks, cracks and the like. Folding strength: The bending strength test is based on JIS P8115. Stiffness: For the stiffness test, JIS P 8125 shall be applied mutatis mutandis.

Mold resistance: A sample (50 × 50 mm) was dried in a desiccator, weighed, and a test piece was placed on a sterilized and solidified medium. A spore suspension of the test bacterium was spray-inoculated.
Cultivate 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 removed with a filter paper, dried in a desiccator, and the weight loss is measured. Decomposability in compost: A sample is buried in compost at a temperature of 35 ° C. and a humidity of 30%, and a decomposability test is performed to examine changes after two 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 a thickness of 15 mm.
A magnetic recording layer consisting of a μm magnetic coating was formed. next,
On this, a base layer was formed to a thickness of 2 μm, on which a heat-sensitive recording layer, an intermediate layer and a protective layer were sequentially formed to prepare a heat-sensitive recording medium. The tensile strength of this card is 68 N / mm ²
Met. The impact strength test was passed, the bending strength was 200 times or more, and the stiffness was 1.76 mN · m or more. In the mold resistance test, no growth of mold was observed after 4 weeks. Moreover, in the compost decomposability test, the shape easily collapsed by external force after 2 months.

Example 2 Instead of the polymer of Production Example 1, 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, and a thermosensitive recording medium was produced in the same manner as in Example 1. Created. The tensile strength of this card was 68 N / mm ² .
The impact strength test was passed, the bending strength was 200 times or more, and the stiffness was 1.76 mN · m or more. In the mold resistance test, no growth of mold was observed after 4 weeks. Also,
In the compost degradability test, the shape easily collapsed by external force after 2 months.

Example 3 Instead of the polymer of Production Example 1, 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, and a thermosensitive recording medium was produced in the same manner as in Example 1. Created. The tensile strength of this card was 60 N / mm ² .
The impact strength test was passed, the bending strength was 200 times or more, and the stiffness was 1.76 mN · m or more. In the mold resistance test, no growth of mold was observed after 4 weeks. Also,
In the compost degradability test, the shape easily collapsed by external force after 2 months.

Example 4 Instead of the polymer of Production Example 1, 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, and a thermosensitive 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 was passed, the bending strength was 200 times or more, and the stiffness was 1.76 mN · m or more. In the mold resistance test, no growth of mold was observed after 4 weeks. Also,
In the compost degradability test, the shape easily collapsed by external force after 2 months.

Example 5 The same polylactic acid sheet as in Example 1 was recrystallized at 80 ° C. for 1 hour to obtain a heat-sensitive recording medium in the same manner as in Example 1. The tensile strength of this card is 78
N / mm ² . The impact strength test was passed, the bending strength was 200 times or more, and the stiffness was 1.76 mN · m or more. In the mold resistance test, no growth of mold was observed after 4 weeks. Moreover, in the compost decomposability test, the shape easily collapsed by external force after 2 months.

COMPARATIVE EXAMPLE 1 Instead of the polymer of Production Example 1, a biopolymer (manufactured by ICI), which is a random copolymerized polyester of 3-hydroxybutyrate and 3-hydroxyvalerate, was prepared in the same manner as in Example 1. A sheet having a thickness of 188 μm was obtained, and a thermosensitive recording medium was prepared in the same manner as in Example 1. The tensile strength of this card was as low as 24 N / mm ² , passed the impact strength test, the bending strength was 200 times or more, and the stiffness was 0.7.
The value was as low as 3 mN · m. In the mold resistance test, 4
After a week, mold had grown on more than 2/3 of the area of the card. In addition, in the compost degradation test, it had disappeared after 2 months.

Comparative Example 2 Instead of the polymer of Production Example 1, 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. A thermosensitive recording medium was prepared in the same manner as in method 1. The tensile strength of this card was as low as 22 N / mm ² , passed the impact strength test, and the bending strength was more than 200 times.
The stiffness was a low value of 0.53 mN · m. In the mold resistance test, after 4 weeks, mold had grown on at least 2/3 of the area of the curd. In addition, in the compost degradation test, it had disappeared after 2 months.

[0025]

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

[Brief description of the drawings]

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

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI C08L 67:04 C08L 67:04 (56) References JP-A-5-42786 (JP, A) JP-A-4-335060 (JP) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C08J 5/18 B42D 15/10 C08G 63/06 C08L 67/04

Claims (3)

(57) [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 method of claim 1, wherein the hydroxycarboxylic acid is glycolic acid,
2. The degradable card according to claim 1, wherein the card is 6-hydroxycaproic acid.