JPH09208817A - Oriented lactic acid base polymer film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oriented lactic acid base polymer film improved in, e.g. stretchability, mechanical strength, durability and the accuracy of thickness. SOLUTION: This film contains 100 pts.wt. polylactic acid or copolymer of lactic acid with other hydroxycarboxylic acid and 3-25 pts.wt. of at least one inorganic filler selected from a group consisting of titanium oxide with a mean particle diameter of 0.1-0.5μm, calcium carbonate with a mean particle diameter of 0.3-6μm, barium sulfate with a mean particle diameter of 0.1-2μm, silica with a mean particle diameter of 1-12μm, kaolin with a mean particle diameter of 0.5-10μm and talc with a mean particle diameter of 0.1-10μm, and is stretched 1.3- to 5-fold at least in the uniaxial direction.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a lactic acid-based polymer stretched film. More specifically, it relates to a stretched lactic acid-based polymer film which has degradability in a natural environment and has excellent stretchability, mechanical strength, durability, thickness accuracy and the like.

[0002]

2. Description of the Related Art In recent years, the problem of plastic waste has been highlighted. Plastic waste such as packaging materials and disposable cards are
They were either discarded, incinerated, or disposed of by landfill. However, when such plastic waste is incinerated, the heat of combustion is high, which causes a problem of durability of the incinerator and a harmful gas such as polyvinyl chloride, which causes a pollution problem. Further, when it is landfilled, the plastic molded product is not decomposed as it is, but remains in its original form semi-permanently as dust, which poses a problem of affecting the natural environment.

Under these circumstances, various biodegradable plastics that are completely consumed by microorganisms in a natural environment and decompose into carbon dioxide and water which are natural by-products have been invented and are in the stage of practical use. . JP-A-6-340753
In the publication, a composition comprising a polylactic acid or a thermoplastic polymer containing lactic acid and other hydroxycarboxylic acid as a main component can be used as a degradable card,
And it is disclosed that it has high mechanical strength and exhibits durability that can withstand repeated use. .

On the other hand, WO 90/0521 describes the addition of an inorganic compound such as silica or kaolinite to a lactide thermoplastic to change its hardness, strength and temperature resistance. Further, Japanese Unexamined Patent Publication No.
Japanese Patent No. 508819 (WO92 / 01548) discloses a method of biaxially stretching a polylactic acid-based film.

However, by simply adding an inorganic filler to polylactic acid or lactic acid and other hydroxycarboxylic acid copolymers, the stretchability of the film and the mechanical strength and flatness of the resulting biaxially stretched film are improved. It was difficult to do. That is, depending on the type of the inorganic filler that is usually used, the stretchability of the lactic acid-based polymer film is poor, causing breakage, resulting in a marked decrease in productivity, or the film thickness accuracy of the stretchable film is poor, and tensile strength is The mechanical strength and the repeated strength such as folding endurance vary greatly, and no satisfactory industrial products were obtained.

[0006]

In view of the above situation, the object of the present invention is to maintain the degradability in a natural environment at the same level as conventional ones, and to improve the stretchability, mechanical strength and durability. Another object of the present invention is to provide a stretched lactic acid-based polymer film having improved thickness accuracy and the like.

[0007]

DISCLOSURE OF THE INVENTION The present inventors have further added a specific amount of a specific type of inorganic filler to polylactic acid or a copolymer of lactic acid and other hydroxycarboxylic acid, and further, if necessary. The inventors have found that the above problem can be solved by using a lubricant together, and have reached the present invention.

That is, the present invention is based on 100 parts by weight of polylactic acid or a copolymer of lactic acid and other hydroxycarboxylic acid, titanium oxide having an average particle size of 0.1 to 0.5 μm, and an average particle size of 0.3. Calcium carbonate, which is ~ 6 μm,
Barium sulfate having an average particle size of 0.1 to 2 μm, silica having an average particle size of 1 to 12 μm, and an average particle size of 0.5 to 1
Kaolin having an average particle size of 0 μm and an average particle size of 0.1 to 10 μm
Is a lactic acid-based polymer stretched film containing 3 to 25 parts by weight of at least one inorganic filler selected from the group consisting of talc and being stretched 1.3 to 5 times in at least one axial direction. The stretched lactic acid-based polymer film of the present invention preferably contains 0.1 to 2 parts by weight of a lubricant in combination.

The stretched lactic acid-based polymer film of the present invention is
It is a stretched film containing a specific amount of an inorganic filler whose type is carefully selected. Therefore, it has excellent mechanical strength, durability, thickness accuracy and the like. Specifically, it has a strong durability such that the folding endurance is 900 times or more. When a lubricant is included, the coefficient of variation of thickness has a high thickness accuracy of 1.3% or less. Therefore, the lactic acid-based polymer stretched film of the present invention,
It can be suitably used for various film materials, laminated materials, packaging materials and the like. In particular, it is suitable as a material such as a prepaid card that requires strong durability and high thickness accuracy. In addition, since the degradability in the natural environment is the same as that of the conventionally known ones, it decomposes into carbon dioxide gas and water relatively quickly after use and should be accumulated as waste, even if it is discarded in the natural environment. There is no.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The stretched lactic acid polymer film of the present invention is obtained by adding and mixing a specific inorganic filler and, if necessary, a specific amount of lubricant to polylactic acid or a copolymer of lactic acid and other hydroxycarboxylic acid. The composition produced thereby is formed into a film using, for example, a forming machine such as an extruder, and the obtained unstretched film is produced by stretching at least a uniaxial direction to a specific ratio. It Hereinafter, the present invention will be described in detail.

Among the polylactic acid or lactic acid-hydroxycarboxylic acid copolymer (hereinafter abbreviated as lactic acid-based polymer) used in the present invention, polylactic acid has a structural unit of L-
Poly (L-lactic acid) consisting only of lactic acid, poly (D-lactic acid) consisting only of D-lactic acid, poly (DL-lactic acid) composed of L-lactic acid units and D-lactic acid units in various proportions, etc. Is mentioned.

Examples of the hydroxycarboxylic acid of the lactic acid-hydroxycarboxylic acid copolymer include glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 4-hydroxyvaleric acid, 5-hydroxyvaleric acid and 6-hydroxycaproic acid. . Of these, glycolic acid is particularly preferable. The lactic acid-based polymer can be obtained by selecting a necessary one from L-lactic acid, D-lactic acid and hydroxycarboxylic acid as a raw material monomer or a comonomer, and directly performing dehydration polycondensation. It can also be obtained by ring-opening polymerization of lactide, which is a cyclic dimer of lactic acid, and cyclic esters such as glycolide, caprolactone, propiolactone, butyrolactone, and valerolactone, which are cyclic dimers of glycolic acid. it can. However, in the case of industrial production, the method of dehydration polycondensation is preferable for the lactic acid-based polymer in consideration of cost and simplification of the process.

In the case of direct dehydration polycondensation, lactic acid or lactic acid and other hydroxycarboxylic acid are subjected to azeotropic dehydration condensation, preferably in the presence of an organic solvent, especially a diphenyl ether solvent, and particularly preferably distilled by azeotropic distillation. By removing water from the solvent taken out and returning the substantially anhydrous solvent to the reaction system, polymerization is carried out to obtain a high-molecular-weight lactic acid-based polymer having strength suitable for the present invention.

The molecular weight of the lactic acid type polymer affects the processability, strength and degradability of the stretched film of the present invention. When the molecular weight is low, the strength of the obtained stretched film decreases,
May break under tension when used. Also, the decomposition rate becomes faster. On the other hand, if the molecular weight is high, the processability is lowered and it becomes difficult to form a film. Considering this point,
The molecular weight of the lactic acid-based polymer used in the present invention is 10,0.
The range of about 00 to 1,000,000 is preferable. Furthermore, a preferable range is 100,000 to 300,000.

When the lactic acid-based polymer is a lactic acid-hydroxycarboxylic acid copolymer, the content of lactic acid units in the copolymer affects the degradability of the film. From this viewpoint, a copolymer containing 40 mol% or more lactic acid units is preferable. More preferable content of the lactic acid unit is
When the lactic acid-hydroxycarboxylic acid copolymer is a lactic acid-glycolic acid copolymer, it is a copolymer containing at least 70 mol% lactic acid units. Further, when the lactic acid-hydroxycarboxylic acid copolymer is a lactic acid-6-hydroxycaproic acid copolymer, a copolymer containing 40 to 70 mol% of lactic acid units is more preferable.

The type of inorganic filler used in the present invention is limited. Specific examples include 6 types of inorganic fillers such as titanium oxide, calcium carbonate, barium sulfate, silica, kaolin, and talc. These may be used alone or in combination of two or more. Of these, titanium oxide is most preferable in consideration of mechanical properties such as folding endurance of the obtained stretched film and the variation coefficient of thickness. A composition obtained by blending these inorganic fillers with a lactic acid-based polymer has a good biaxial stretchability, and therefore has a mechanical strength such as a tensile strength required for a stretched film and a folding endurance. Such durability can be improved.

The amount of the inorganic filler compounded with the lactic acid-based polymer is 3 to 25 relative to 100 parts by weight of the lactic acid-based polymer.
Parts by weight, preferably 5 to 25 parts by weight. Compounding amount is 3
When the amount is less than the weight part, sufficient durability as the object of the present invention cannot be obtained, and when it exceeds 25 parts by weight, biaxial stretchability is deteriorated and mechanical strength is lowered.

Among the inorganic fillers used in the present invention, titanium oxide is classified into anatase type, rutile type and brookite type depending on its crystal form, and any of them can be used and the average particle size thereof is 0. It is preferably 1 to 0.5 μm. More preferably 0.1 to 0.3 μm
It is. Further, in order to improve the dispersibility in the lactic acid-based polymer, it is possible to use those whose surface is coated with an oxide such as alumina, silica, zinc oxide or the like, or which has been surface-treated with an aliphatic polyol or the like. Examples of commercially available products include TAIPEK [trade name, manufactured by Ishihara Sangyo Co., Ltd.] and Tyton [trade name, manufactured by Sakai Chemical Industry Co., Ltd.].

The crystalline form of calcium carbonate may be any of calcite, aragonite and vaterite, and the one having an average particle size of 0.3 to 6 μm is preferably used. As a commercial product, NCC [Nitto Koka Kogyo Co., Ltd.
Product name, manufactured by Takehara Chemical Co., Ltd., and the like. Barium sulphate is precipitated barium sulphate produced by a chemical reaction from barite and has an average particle size of 0.1 to 2 μm. Examples of commercially available products include precipitated barium sulfate TH and precipitated barium sulfate ST (trade name, manufactured by Barite Industry Co., Ltd.).

Silica is a silicic acid obtained naturally or synthetically, and one having an average particle size of 1 to 12 μm can be preferably used. Examples of commercially available products include Sylysia (trade name, manufactured by Fuji Silysia Chemical Ltd.), Hugh Rex Crystallite (trade name, manufactured by Tatsumori Co., Ltd.) and the like. Kaolin is a naturally occurring hydrous aluminum silicate having an average particle size of 0.5 to 10 μm. Further, a firing type in which water of crystallization is removed can also be used.
Examples of commercially available products include NN Kaolin clay (trade name, manufactured by Tsuchiya Kaolin Industry Co., Ltd.), ASP, Satinton (trade name, manufactured by Engelhard Co., Ltd.) and the like. Talc is a naturally occurring hydrous magnesium silicate having an average particle size of 0.1 to 10 μm. Examples of commercially available products include PK and LMS (trade name, manufactured by Fuji Talc Industry Co., Ltd.).

Thickness accuracy of lactic acid-based polymer stretched film,
Considering mechanical strength and the like, it is preferable to add a specific amount of lubricant. As the lubricant, erucic acid amide, stearic acid amide, oleic acid amide, lauric acid amide, palmitic acid amide, behenic acid amide, ricinoleic acid amide, oxystearic acid amide, methylenebisstearic acid amide, ethylenebisstearic acid amide, ethylene Fatty acid amide lubricant such as bisbehenic acid amide, montanic acid wax, partially saponified montanic acid ester, long chain ester wax such as butyl stearate, fatty acid such as glycerin fatty acid ester, hydroxystearic acid triglyceride, sorbitan fatty acid ester Ester lubricants, metal soap lubricants which are fatty acid metal salts having 12 to 30 carbon atoms such as lead stearate, calcium stearate and calcium hydroxystearate, or these Composite composite lubricants and the like. Among these, erucic acid amide, montanic acid wax, calcium hydroxystearate and the like are preferable.

The amount of the lubricant added is preferably 0.1 to 2 parts by weight based on 100 parts by weight of the lactic acid polymer. If the addition amount is less than 0.1 parts by weight, the degree of improvement in the thickness accuracy of the obtained stretched film will decrease, which is not preferable. If it exceeds 2 parts by weight, the formability of the film is lowered, the flatness and thickness accuracy of the obtained film are lowered, and as a result, the mechanical strength is lowered.

In the present invention, the method of adding and mixing the inorganic filler, the lubricant and the like to the lactic acid type polymer is not particularly limited, and a known mixing method is adopted. For example, an inorganic filler and, if necessary, a lubricant are added to a lactic acid-based polymer and mixed with a ribbon blender, a tumbler, a Henschel mixer, etc., and then at a temperature of 150 to 230 ° C. by a Banbury mixer, a single-screw or twin-screw extruder. Kneaded into pellets,
It is possible to obtain a composition having a rod shape, a powder shape, or the like. If necessary, additives such as an antioxidant, an antistatic agent, and an ultraviolet absorber may be added to the stretched lactic acid-based polymer film of the present invention.

The stretched lactic acid polymer film of the present invention is
The lactic acid-based polymer composition obtained as described above is first formed into an unstretched film using, for example, an extruder equipped with a T die, a circular die, etc., and the obtained unstretched film is rolled. It can be produced by stretching by sequential biaxial stretching method of stretching and tenter stretching, simultaneous biaxial stretching method by tenter stretching, biaxial stretching method by tubular stretching and the like. Considering homogeneity, thickness accuracy, productivity, etc. of the obtained film, the sequential biaxial stretching method by the roll stretching method and the tenter stretching method is preferable.

For example, a stretched film obtained by sequential biaxial stretching in which roll stretching and tenter stretching are combined is manufactured as follows. The lactic acid-based polymer composition described above is added to 50-
Heat treatment is performed at a temperature of 130 ° C., and drying and crystallization are performed. Next, after melt-extruding at a temperature of 130 to 250 ° C. with an extruder equipped with a T-die, it is rapidly cooled by a casting roll at 60 ° C. or less to form a film. In this case, it is preferable to use an air knife or an electrostatic application device in order to bring the molten film into close contact with the roll to improve flatness. Then, the obtained film is passed through a take-up machine and a longitudinal stretching machine at 30 to 80 ° C.
After longitudinally stretching 1.3 to 5 times, preferably 2 to 4 times at a temperature of 10 to 80 ° C, 1.3 to 5 at a temperature of 40 to 80 ° C.
Laterally stretched twice, preferably 2 to 4 times. When the heat resistance (heat shrinkage resistance) of the stretched film is required, it is continuously applied in a tenter under tension at a temperature of 80 to 150 ° C. for 3 to 12
It is preferable to heat-set for 0 seconds.

When the stretching ratio is less than 1.3 times, sufficient mechanical strength and durability as the object of the present invention cannot be obtained, and when it exceeds 5 times, the film is broken, which is not preferable. . Further, if the stretching temperature is out of the above range,
At a lower temperature, the film is not stretched and breaks the film, and at a higher temperature, crystallization occurs, uneven stretching occurs, and the film breaks, which is not preferable.

The thickness of the stretched lactic acid-based polymer film of the present invention is usually 0.01 to 2 mm and is appropriately selected depending on the application.

The lactic acid-based polymer stretched film of the present invention is
It is characterized by excellent durability. The folding endurance, which is an index of durability, is 900 times or more. The upper limit is about 2500 times. Further, by using a lubricant together with the inorganic filler, the film thickness accuracy is improved and the coefficient of variation becomes 1.3% or less. The lower limit is about 0.3%. Therefore, it is particularly preferably used for applications requiring durability and thickness accuracy. A typical application is a prepaid card having a magnetic layer. In this case, when the variation coefficient of the thickness of the stretched film exceeds 5%, the adhesiveness of the magnetic layer, printability, mechanical suitability and the like deteriorate. Further, the folding endurance is preferably 900 times or more in consideration of practical use conditions such as mechanical suitability and durability of the prepaid card. When used as a material such as a prepaid card, the average thickness is preferably 0.1 to 0.5 mm. The stretched lactic acid-based polymer film of the present invention satisfies all of these characteristics.

Other uses of the stretched lactic acid-based polymer film of the present invention include, for example, card materials such as credit cards, cash cards and membership card cards.
In that case, the preferable thickness is about 0.5 to 2 mm.

The coefficient of variation of the film thickness and the folding endurance in the present invention mean the values measured by the methods described in Examples below.

[0031]

The present invention will be described below in further detail with reference to examples. The properties shown in Preparation Examples and Examples were measured by the following methods. (1) Average molecular weight of polymer (weight average molecular weight) It is measured under the following conditions by gel permeation chromatography using polystyrene as a standard. apparatus:
Shimadzu Corporation, type: LC-10AD, detector:
Shimadzu Corporation, model: RID-6A, column: Hitachi Chemical Co., Ltd., model: GL-S350DT-5, GL
-S370DT-5, solvent: chloroform, solution concentration:
1% by weight, injection amount: 20 μl, flow rate: 1.0 ml / mi
n.

(2) Average particle size (μm) of inorganic filler 1 g of a sample is added to 100 ml of water and ultrasonically dispersed for 60 seconds to prepare a dispersion liquid. While stirring, a few ml of the dispersion liquid is rapidly collected using a pipette and added into the sample chamber of the particle size analyzer to measure the average particle size. <Particle size analyzer> Laser diffraction / scattering method particle size analyzer, manufactured by Honeywell, type: Microtrac HRA-UPA
100 (applicable for average particle size less than 5 μm), Microtr
ac HRA-X100 (Applicable to average particle size of 5 μm or more)

(3) Stretchability When a stretched film having a width of 1500 mm is produced for 1000 m, the sample in the stretching step is visually observed, and the presence or absence of breakage is used as a reference to judge as follows. Good (stretchability): The film does not break during the stretching operation. ×
(Poor drawability): A film is broken during the stretching operation.

(4) Variation coefficient of thickness (%) <Measurement point> A stretched film having a width of 1500 mm was used as a sample,
The thickness at 30 points is measured at intervals of 50 mm in the width direction of the film. Same measurement 100mm in the length direction of the film
Repeat 10 times at intervals and measure the thickness at a total of 300 points. From the obtained data, the average value (X) and standard deviation (σ)
And the coefficient of variation (CV) of thickness is calculated by the following equation. CV (%) = (σ / X) × 100 <Measuring machine> Digimatic Micrometer [Mitsutoyo Corporation, Model: BMS-25DM]

(5) Tensile strength (MPa) Regarding the length direction and width direction of the sample, JIS C-23
It is measured by the method specified in 18.

(6) Folding endurance (number of times) For a sample having a thickness of 200 μm, JIS P-8115
It is measured by the method specified in.

Preparation Example 1 216 g (1.5 mol) of L-lactide, 0.01% by weight of tin octoate and 0.03% by weight of lauryl alcohol were charged in a thick cylindrical stainless steel polymerization vessel equipped with a stirrer. After degassing under vacuum for 2 hours, the atmosphere was replaced with nitrogen gas. The mixture was heated at 200 ° C. for 3 hours with stirring under a nitrogen atmosphere. While maintaining the temperature as it was, the air was gradually degassed by a vacuum pump through an exhaust pipe and a glass receiver, and the pressure inside the reaction vessel was reduced to 3 mmHg. One hour after the start of degassing, the distillation of the monomer and low-molecular-weight volatile matter disappeared, so the inside 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 average molecular weight of this polymer was about 100,000. Less than,
The polylactic acid obtained in Preparation Example 1 is referred to as lactic acid-based polymer A.

Preparation Example 2 In a 100-liter reactor equipped with a Dien-Stark trap, 10 kg of 90 mol% L-lactic acid was added at 150 ° C. /
After distilling water while stirring at 50 mmHg for 3 hours,
Tin powder 6.2 g was added, and the mixture was further stirred at 150 ° C./30 mmHg for 2 hours for oligomerization. To this oligomer, 28.8 g of tin powder and 21.1 kg of diphenyl ether were added, an azeotropic dehydration reaction was carried out at 150 ° C./35 mmHg, and 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 packed with 4.6 kg of molecular sieve 3A and then returned to the reactor, and the temperature was adjusted to 40 at 150 ° C./35 mmHg.
The reaction was carried out for a time to obtain a polylactic acid solution having an average molecular weight of 110,000. After adding 44 kg of dehydrated diphenyl ether to this solution and diluting, it was cooled to 40 ° C., and the precipitated crystals were filtered, washed with 10 kg of n-hexane three times, and 60 ° C. /
It was dried at 50 mmHg. This powder was added with 0.5N hydrochloric acid 1
After adding 2 kg and 12 kg of ethanol, stirring at 35 ° C. for 1 hour, filtering, and drying at 60 ° C./50 mmHg, 6.1 kg of polylactic acid powder having an average particle diameter of 30 μm (yield 85
%) Was obtained. The average molecular weight of this polymer was about 110,000. Hereinafter, the polylactic acid obtained in Preparation Example 2 is referred to as lactic acid-based polymer B.

Preparation Example 3 From 9.2 kg of 98 mol% DL-lactic acid, poly DL-lactic acid was obtained in the same manner as in Preparation Example 2 and pelletized. The average molecular weight of this polymer was about 100,000. Hereinafter, Preparation Example 3
The polylactic acid obtained in step 1 is referred to as lactic acid-based polymer C.

Preparation Example 4 A copolymer of lactic acid and hydroxycarboxylic acid was obtained in the same manner as in Preparation Example 2 except that 10.0 kg of L-lactic acid was changed to 9.0 kg of L-lactic acid and 1.0 kg of glycolic acid. . The average molecular weight of this polymer was about 100,000. Hereinafter, Preparation Example 4
The copolymer obtained in step 1 is referred to as lactic acid-based polymer D.

Example 1 To 100 parts by weight of the lactic acid-based polymer A obtained in Preparation Example 1 was added 5 parts by weight of barium sulfate [manufactured by Barite Industry Co., Ltd., trade name: Barium Sulfate ST], and after mixing with a ribbon blender. A lactic acid-based polymer composition was obtained by melt-kneading with a biaxial kneading extruder at a cylinder temperature of 170 to 210 ° C. and pelletizing. This is dried in an oven at 80 ° C., heat treated to crystallize the polymer, and then extruded at a temperature condition of 150 to 200 ° C. with a single screw extruder equipped with a T die,
Cooled with a casting roll at ℃, average thickness 1.5
mm unstretched sheet was obtained. Subsequently, it was longitudinally stretched at a draw ratio of 2.5 times on a hot roll at 60 ° C., and then transversely stretched at a temperature of 70 ° C. at a draw ratio of 2.5 times by a tenter, and further,
Heated in a tenter under tension at a temperature of 130 ° C. for 30 seconds, cooled, and wound up by a winder to obtain an average thickness of 20.
A 0 μm stretched film was obtained. The variation coefficient of thickness, tensile strength and folding strength of the obtained stretched film were measured by the above methods, and the results are shown in [Table 1].

Examples 2 to 7 In the same manner as in Example 1, the inorganic fillers were added in the amounts shown in Table 1 to 100 parts by weight of each of the lactic acid polymers B to D obtained in Preparation Examples 2 to 7. A lactic acid-based polymer composition was produced by the method. The inorganic fillers used were titanium oxide [manufactured by Ishihara Sangyo Co., Ltd., trade name: Taipek CR60-2], silica [manufactured by Fuji Silysia Chemical Ltd., trade name: Sylysia],
Calcium carbonate [manufactured by Dowa Calfine Co., Ltd., trade name:
ACE-25], Kaolin [Tsuchiya Kaolin Industry Co., Ltd.
Manufactured by Fuji Talc Industry Co., Ltd., trade name: LMS-200]. Using the obtained lactic acid-based polymer composition, a stretched film was obtained at the stretch ratio shown in [Table 1] in the same manner as in Example 1. The tensile strength and folding endurance of the obtained stretched film were measured by the above methods, and the results are shown in [Table 1].

Examples 8 to 16 To 100 parts by weight of each of the lactic acid polymers A to D obtained in Preparation Examples 1 to 4, each inorganic filler and each lubricant were added in the amounts shown in Table 1, and Example 1 was added. A lactic acid-based polymer composition was produced in the same manner as in. The inorganic filler used was titanium oxide [manufactured by Ishihara Sangyo Co., Ltd., trade name: TAIPAKE CR58-2],
Silica [Fuji Silysia Chemical Ltd., trade name: Sylysia], Calcium carbonate [Nitto Koka Kogyo Co., Ltd., trade name: NCC45], Kaolin [Tsuchiya Kaolin Industry Co., Ltd.]
Manufactured by Fuji Talc Industry Co., Ltd., trade name: PKP-80 !. The lubricant used was montanic acid wax [made by Hoechst Industry Co., Ltd., trade name: Hostalve WE-4],
Amide erucic acid [Nippon Kasei Co., Ltd., trade name: Diamid L-200] or calcium hydroxystearate [Kawaken Fine Chemicals Co., Ltd., trade name:
CS-6]. Using the obtained lactic acid-based polymer composition, a stretched film was obtained at the stretch ratio shown in [Table 1] in the same manner as in Example 1. The tensile strength and folding endurance of the obtained stretched film were measured by the above methods, and the results are shown in [Table 1].

[0044]

[Table 1]

Comparative Examples 1 to 4 To 100 parts by weight of each of the lactic acid-based polymers A and B obtained in Preparation Examples 1 and 2, the respective inorganic fillers were added in the compounding amounts shown in [Table 2], and the same as in Example 1. A lactic acid-based polymer composition was obtained by the method. The inorganic filler used was zinc oxide [Mitsui Mining & Smelting Co., Ltd., trade name: EP], magnesium oxide [Kyowa Chemical Industry Co., Ltd., trade name: Kyowamag 150], titanium oxide [Ishihara Sangyo Co., Ltd.]. Product name: Taipaque CR6
0-2]. Using the obtained composition, a stretched film was obtained in the same manner as in Example 1 at a stretch ratio shown in [Table 1]. The tensile strength and folding endurance of the obtained stretched film were measured by the above methods, and the results are shown in [Table 2].

Comparative Examples 5 to 14 To 100 parts by weight of each of the lactic acid polymers A to D obtained in Preparation Examples 1 to 4, the inorganic fillers and the lubricants were added in the amounts shown in Table 2, and Example 1 was used. A lactic acid-based polymer composition was produced in the same manner as in. The inorganic filler used was titanium oxide [manufactured by Ishihara Sangyo Co., Ltd., trade name: TTO-55, Taipaque C].
R60-2], barium sulfate [produced by Sakai Chemical Industry Co., Ltd., trade name: BARIFINE BF-10, precipitating barium sulfate special product], talc [produced by Fuji Talc Industry Co., Ltd., trade name: LMS-300, NK -48], silica [Fuji Silysia Chemical Ltd., trade name: Sylysia 470], calcium carbonate [Nitto Koka Kogyo Co., Ltd., trade name: SS3
0], Kaolin [Tsuchiya Kaolin Industry Co., Ltd., trade name:
NN Kaolin clay]. Using the obtained lactic acid-based polymer composition, a stretched film was obtained at the stretch ratio shown in [Table 2] in the same manner as in Example 1. The tensile strength and folding endurance of the obtained stretched film were measured by the above methods, and the results are shown in [Table 2].

Comparative Example 15 Using the lactic acid-based polymer powder B obtained in Preparation Example 2, titanium oxide [manufactured by Ishihara Sangyo Co., Ltd., trade name: TAIPAKE CR60]
-2] is added in the compounding amounts shown in [Table 2] and melt-extruded with a twin-screw kneading extruder at a cylinder temperature of 170 to 210 ° C.
Pelletized. This is dried and heat-treated in an oven to crystallize the polymer, which is then extruded with a single screw extruder equipped with a T-die at a temperature condition of 150 to 200 ° C.
Cooled with a casting roll at 5 ℃, average thickness 20
An unstretched film of 0 μm was obtained. The tensile strength and folding endurance of the obtained unstretched film were measured by the above methods, and the results are shown in [Table 2].

[0048]

[Table 2]

[0049]

The lactic acid-based polymer stretched film of the present invention not only decomposes in a natural environment, but also has excellent mechanical strength and durability. By using the lubricant together with the inorganic filler, those properties are further excellent and the thickness accuracy is also excellent. Therefore, the stretched lactic acid-based polymer film of the present invention can be widely used for various film materials such as prepaid cards, laminated materials, and packaging materials. In addition, after use, it is decomposed into carbon dioxide gas and water relatively quickly even if it is discarded in a natural environment, so it does not accumulate as waste.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C08K 5/10 KJV C08K 5/10 KJV // B29K 67:00 105: 16 (72) Inventor crocodile Hirotaka 2-1, Tango-dori, Minami-ku, Aichi Prefecture, Mitsui Toatsu Chemical Co., Ltd. (72) Inventor Masumi Sarutawa 3-5, Kasumigaseki, Chiyoda-ku, Tokyo Mitsui Toatsu Chemical Co., Ltd. (72) Inventor Kazuhiko Suzuki 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemical Co., Ltd.

Claims (10)

[Claims] 1. Titanium oxide having an average particle size of 0.1 to 0.5 μm, and an average particle size of 0.3 to 6 μm, relative to 100 parts by weight of polylactic acid or a copolymer of lactic acid and other hydroxycarboxylic acid. Calcium carbonate with an average particle size of 0.
1 to 2 μm barium sulfate, average particle size is 1 to 12 μm
m, silica having an average particle size of 0.5 to 10 μm, kaolin having an average particle size of 0.1 to 10 μm, and at least one inorganic filler 3 selected from the group consisting of talc having an average particle size of 0.1 to 10 μm.
.About.25 parts by weight, and 1.
A lactic acid-based polymer stretched film stretched 3 to 5 times. 2. The stretched lactic acid-based polymer film according to claim 1, having an average thickness of 0.01 to 2 mm. 3. The inorganic filler has an average particle size of 0.1 to 0.5.
The stretched lactic acid-based polymer film according to claim 1, which is titanium oxide having a thickness of μm. 4. The folding endurance is 900 times or more.
The lactic acid-based polymer stretched film described. 5. The stretched lactic acid-based polymer film according to claim 1, which contains 0.1 to 2 parts by weight of a lubricant based on 100 parts by weight of polylactic acid or a copolymer of lactic acid and another hydroxycarboxylic acid. 6. The inorganic filler has an average particle size of 0.1 to 0.5.
The stretched lactic acid-based polymer film according to claim 5, which is titanium oxide having a thickness of μm. 7. The stretched lactic acid-based polymer film according to claim 5, wherein the lubricant is at least one compound selected from the group consisting of a fatty acid amide lubricant, a fatty acid ester lubricant and a metal soap lubricant. 8. The stretched lactic acid-based polymer film according to claim 5, which has an average thickness of 0.01 to 2 mm, a variation coefficient of thickness of 1.3% or less, and a folding endurance of 900 times or more. 9. The inorganic filler has an average particle size of 0.1 to 0.5.
The stretched lactic acid-based polymer film according to claim 8, which is titanium oxide having a thickness of μm. 10. Use of the stretched lactic acid-based polymer film according to claim 1, which has an average thickness of 0.1 to 0.5 mm, as a material for a prepaid card.