WO2002034818A1

WO2002034818A1 - Biaxially oriented aliphatic polyester film and process for producing the same

Info

Publication number: WO2002034818A1
Application number: PCT/JP2000/007397
Authority: WO
Inventors: Shigenori Terada; Jun Takagi
Original assignee: Mitsubishi Plastics Inc.
Priority date: 1999-08-23
Filing date: 2000-10-23
Publication date: 2002-05-02
Also published as: JP2001059029A

Abstract

An aliphatic polyester film which has satisfactory slip properties better than those of polylactic acid films, is inhibited from meandering or creasing, retains stiffness, strength, and low heat shrinkability, and optionally has transparency. The film comprises an aliphatic polyester consisting mainly of a polylactic acid polymer, contains inorganic particles, and has an average surface roughness (Ra) of 0.01 < Ra ≤ 0.08.

Description

Specification

Biaxially oriented aliphatic polyester film and method for producing the same

The present invention relates to a biaxially oriented aliphatic polyester film and a method for producing the same. Background art

Many conventional plastic products, especially plastic packaging materials, are often discarded immediately after use, and problems with their disposal have been pointed out. Typical plastics for general packaging include polyethylene, polypropylene, PET, etc., but these materials generate a large amount of heat during combustion and may damage the combustion furnace during the combustion process. In addition, polyvinyl chloride, which is still widely used, cannot burn because of its self-extinguishing properties. In addition, plastic products, including materials that cannot be incinerated, are often landfilled.However, due to their chemical and biological stability, they remain with little decomposition and shorten the life of the landfill. I'm having a problem. On the other hand, there is a demand for one that has a low calorific value, decomposes in soil, and is safe, and much research has been conducted.

One example is polylactic acid. Polylactic acid has a calorific value of combustion less than half that of polyethylene, and hydrolyses naturally in soil and water, and then becomes harmless degradation products by microorganisms. At present, research is being conducted to obtain molded articles, specifically, containers such as films, sheets, and bottles, using polylactic acid.

By the way, when a film made of polylactic acid is manufactured, if the film does not slip smoothly, the film may be wound continuously during the production of the film or in the secondary processing such as printing and laminating with a winder or the like. This causes problems such as meandering and wrinkling.

Therefore, an object of the present invention is to improve the slip of a film made of polylactic acid, to suppress the meandering and wrinkling of the film, and to obtain the film's waist, strength, low heat shrinkage, and It is an object of the present invention to provide a slippery aliphatic polyester film while maintaining transparency according to the conditions. Disclosure of the invention

The present invention comprises an aliphatic polyester having a polylactic acid-based polymer as a main component, is blended with inorganic particles, and has an average roughness Ra of the film surface of 0.01 <Ra≤0.08. Thus, the above problem was solved.

Since the resulting aliphatic polyester-based film has a roughness within a predetermined range, a film having an appropriate sliding property can be obtained. For this reason, the meandering and wrinkling of the film can be suppressed. BEST MODE FOR CARRYING OUT THE INVENTION

The biaxially oriented aliphatic polyester film according to the present invention is made of an aliphatic polyester mainly containing a polylactic acid polymer, is blended with inorganic particles, and has a film surface with a predetermined average roughness Ra. .

The above-mentioned polylactic acid-based polymer refers to a polymer mainly composed of L-, D- or DL-lactic acid units, and is a polymer of only polylactic acid, or L-, D- or DL-lactic acid and hydro- Copolymers with xycarboxylic acid, aliphatic dicarboxylic acid (including alicyclic groups; the same applies hereinafter) and / or aliphatic diols, and those containing 50% or more of a polylactic acid component.

The ratio of L-lactic acid to D-lactic acid in the polylactic acid-based polymer should be 100: 0 to 94: 6 or 6:94 to 0: 1 in order to obtain a desirable surface roughness. 0 0 is preferred. If the ratio is smaller than 94: 6 and larger than 6:94, the film cannot be sufficiently crystallized by heat treatment after stretching, and the heat shrinkage of the film cannot be suppressed. In addition, the orientation is relaxed, and no improvement in physical properties due to the effect of the orientation is observed. As described later, the inorganic particles blended during stretching protrude, the surface is roughened, and the slip of the film is improved. However, in the case of a polylactic acid-based polymer having low crystallinity or not crystallizing, the film is subjected to heat treatment. The inorganic particles protruding with the relaxation of the orientation are buried in the film again, and a film with good slip cannot be obtained. The present invention In addition, it is extremely important to use a polylactic acid-based polymer having a high crystallinity in the above range together with the blending of the inorganic particles in the production of the oriented film through the heat treatment step. As the polymerization method, a known method such as a condensation polymerization method or a ring-opening polymerization method can be employed. <For example, in the condensation polymerization method, L-lactic acid, D-lactic acid, or these and other monomers described above are used. By directly dehydrating and condensing the mixture of the above, a polylactic acid-based polymer having an arbitrary composition can be obtained.

In the ring-opening polymerization method (lactide method), lactide, which is a cyclic dimer of lactic acid, is converted into lactide using a selected catalyst, if necessary, using a polymerization regulator and the like. By mixing and polymerizing the other monomers, a polylactic acid-based polymer can be obtained.

The preferred range of the weight average molecular weight of the polylactic acid polymer used in the present invention is 60,000 to 700,000, more preferably 80,000 to 400,000, and particularly preferably 100,000. ~ 300,000. If the molecular weight is smaller than 60,000, practical physical properties such as mechanical properties and heat resistance are hardly exhibited, and if it is larger than 70,000, the melt viscosity is too high and the moldability may be poor.

Examples of other monomers copolymerized with polylactic acid, such as other hydroxycarboxylic acids, aliphatic dicarbonic acids and / or aliphatic diols, include the following. In other words, when lactic acid has lactic acid having a predetermined optical isomer, lactic acid having another optical isomer (for example, D-lactic acid for L-lactic acid and L-lactic acid for D-lactic acid) Monolactic acid). Hydroxycarboxylic acids include glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxy-1-n-butyric acid, 2-hydroxy-3-, 3-dimethylbutyric acid, 2—Hydroxy-1 3—Methylbutyric acid, 2-Methyllactate, 2-Hydroxycaproic acid and other bifunctional aliphatic hydroxycarboxylic acids, and lactones such as hydroprolactone, petyrolactone, and norrelactone Kind.

Examples of the aliphatic dicarboxylic acids include aliphatic dicarponic acids such as succinic acid, adipic acid, suberic acid, sebacic acid, dodecandioic acid, and anhydrides and derivatives thereof. Examples of the aliphatic diol include aliphatic diols such as ethylene glycol, butanediol, hexanediol, octanediol, cyclopentenediol, cyclohexanediol, and cyclohexanedimethanol; Derivatives thereof. In any case, those having a bifunctional compound as a main component having an alkylene group or a cycloalkylene group having 2 to 10 carbon atoms are preferable. Of course, two or more of these carboxylic acid components and alcohol components may be used.

Further, the aliphatic polyester as a small amount copolymerization,

(a) carboxylic acid, alcohol or hydroxycarboxylic acid unit having three or more functional groups,

(b) non-aliphatic dicarboxylic acid units and / or non-aliphatic diol units,

Or a small amount of a chain extender residue.

The unit of the above (a) is used for the purpose of providing a branch in the polymer to improve the melt viscosity, and specifically, malic acid, tartaric acid, citric acid, trimellitic acid, and pyromellitic acid. Alternatively, there may be mentioned a polyfunctional component such as erythritol pentotrimethylolpropane. If these components are used in large amounts, the resulting polymer will have a crosslinked structure and will not be thermoplastic, or even if it is a thermoplastic, a microgel with a partially highly crosslinked structure will be formed. There is a possibility that. Therefore, the proportion of these polyfunctional components contained in the polymer is very small, and is limited to a level that does not greatly affect the chemical and physical properties of the polymer. In the above (b), specific examples of the non-aliphatic dicarboxylic acid include terephthalic acid and the like, and examples of the non-aliphatic diol include an ethylene oxide adduct of bisphenol A and the like. Is raised.

The aliphatic polyester contains a polylactic acid-based polymer as a main component, but may contain other resin components (hereinafter, referred to as “other resin components”). In addition, examples of the resin component include aliphatic polyesters other than the polylactic acid-based polymer. Examples of the aliphatic polyester other than the polylactic acid-based polymer include a polymer of hydroxycarboxylic acid other than lactic acid, and a polyester composed of an aliphatic dicarboxylic acid and / or an aliphatic diol. The hydroxycarboxylic acids, aliphatic dicarboxylic acids and aliphatic diols used herein are the same as described above.

Further, the aliphatic polyester may contain the same small amount of copolymerized units as described above, and may also contain a small amount of a chain extender residue.

To adjust the polyester consisting of the above aliphatic carboxylic acid and aliphatic diol Any known method such as a direct method and an indirect method can be employed. For example, the direct method is a method of directly polymerizing an aliphatic carboxylic acid and an aliphatic diol while removing water contained in these components or generated during the polymerization to obtain a high molecular weight product. . The indirect method is an indirect production method in which a small amount of a chain extender is used to increase the molecular weight after polymerization to the degree of an oligomer, as in the case of the polylactic acid-based polymer.

The other resin component preferably has a weight average molecular weight of 50,000 to 250,000. If the weight-average molecular weight is less than 50,000, the properties as a polymer are inferior, and not only does not improve the heat sealing property, but also causes problems such as temporary bleeding on the film surface. Also, if it is larger than 250,000, the melt viscosity becomes too high. This leads to a decrease in the mixing property with polylactic acid and a decrease in extrudability when forming a film like polylactic acid.

It is preferable that the other resin component has a glass transition point (T g) of 0 ° C. or less from the viewpoint of the effect of improving impact resistance and cold resistance.

Particularly suitable other resin components include, for example, polyethylene suberate, polyethylene sebacate, polyethylene decane dicarboxylate, polybutylene succinate, polybutylene adipate, polybutylene sebacate, polybutylene succinate acetate. Copolymers.

In the present invention, a block copolymer of a polylactic acid-based polymer and another resin component (partially transesterified product, a small amount of chain extender residue) may be used together with or instead of the other resin component. Also, products containing) can be used. This block copolymer can be prepared by any method. For example, either a polylactic acid-based polymer or another resin component is separately prepared as a polymer, and the other constituent monomer is polymerized in the presence of the polymer. Usually, a block copolymer of polylactic acid and another resin component is obtained by polymerizing lactide in the presence of another resin component prepared in advance. Basically, the polymerization can be carried out in the same manner as in the case of preparing a polylactic acid-based polymer by the lactide method, only with the difference that other resin components coexist. <At this time, if the polymerization of lactide proceeds At the same time, an appropriate transesterification reaction occurs between polylactic acid and other resin components, and a copolymer having relatively high randomness can be obtained. When an aliphatic polyester urethane having a urethane bond is used as a starting material Also produces ester-amide exchange.

The inorganic particles refer to particles of an inorganic substance. Examples of the inorganic material constituting the inorganic particles include silicon dioxide such as silica, calcium carbonate, magnesium carbonate, silica, titanium dioxide, kaolin, and alumina, and preferably silicon dioxide such as silica, calcium carbonate, and the like. Examples thereof include magnesium carbonate, talc, titanium dioxide, and kaolin. Particularly preferred is silicon dioxide such as silica. One of the above-mentioned inorganic particles may be used alone, or a mixture of two or more thereof may be used.

The mixing amount of the inorganic particles is preferably from 0.01 to 120 parts by weight, more preferably from 0.01 to 5 parts by weight, based on 100 parts by weight of the aliphatic polyester. If the amount is less than 0.01 parts by weight, the effect of imparting lubricity is not obtained. On the other hand, if the amount is more than 120 parts by weight, the film cannot be stretched normally, and even if the film can be stretched, defects such as holes are generated. The average particle diameter of the inorganic particles is preferably from 0.1 to 5 m. These inorganic particles can be measured using a sedimentation balance measurement method, a Coal-Yuichi counter measurement method, a light scattering method, or the like.

The larger the average particle diameter is, the rougher the surface of the film is, the better the slipperiness is, and the smaller the coefficient of friction is. The same effect is obtained as the number of blending parts increases. However, if the average particle size is too large, the smoothness of the surface is reduced, so that printing loss occurs when printing on a film, or scratches occur when the inorganic particles having high hardness rub against each other between the film surfaces. . When the number of blending parts is much larger than that of the resin component, the film may not be stretched. Even if it can be stretched, it may cause defects such as holes. On the other hand, if the average particle size is too small, the effect of providing lubricity is too low. In the case of a film that requires transparency, it is necessary to reduce the number of compounding parts as much as possible. Also, even if the number of parts is small, it is difficult to obtain a transparent film if the particle diameter is large. Haze can be used as a definition of transparency. This can be measured by JISK 7105. The haze is preferably 10% or less, and if the haze exceeds 10%, sufficient transparency may not be obtained.

When it is desired to obtain transparency, it is important that the content be at most about 0.5 part, though it depends on the type and particle size of the inorganic particles to be blended and the thickness of the film. Film If the haze exceeds 10%, it lacks clearness.

In addition, these formulations can roughen the surface of the film and impart lubricity, and more specifically, lower the coefficient of friction of the film.

In terms of preventing the physical properties such as mechanical strength of the film from being significantly reduced, the average particle diameter of the inorganic particles should be 0.1 to 4 m and the number of parts should be 0.01 to 3 parts by weight. In addition, from the viewpoint of obtaining a film with high transparency (specifically, a haze of 10% or less) and a film with excellent lubricity, the average particle diameter is 0.5. More preferably, the mixing amount is in the range of 0.02 to 1 part by weight.

The biaxially oriented polylactic acid film according to the present invention can be manufactured by the following method. The above-mentioned aliphatic polyester and inorganic particles including the polylactic acid-based polymer and the aliphatic polyester are charged into the same extruder and mixed. Then, by directly extruding through a die, a film can be directly produced. In addition, a pellet can be produced by extruding the film into a strand shape, and the film can be produced again by an extruder. In each case, the reduction in molecular weight due to decomposition must be taken into consideration, but the latter is better to be selected for uniform mixing. After fully drying the aliphatic polyester to remove water, it is melted by an extruder. The melt extrusion temperature of the polylactic acid-based polymer is appropriately selected in consideration of the fact that the melting point changes depending on the composition ratio of the L-lactic acid structure and the D-lactic acid structure, and the melting point and mixing ratio of the aliphatic polyester. In practice, a temperature range of 100-250 ° C is usually chosen.

For the purpose of adjusting various physical properties, a heat stabilizer, a light stabilizer, a light absorber, a plasticizer, an inorganic filler, a colorant, a pigment, and the like can be added to these mixtures.

In the film thus obtained, when the stretching ratio is low, the particles do not project on the film surface. For this reason, it is necessary to sufficiently orient the film in order to protrude the particles and improve the surface roughness of the film. Specifically, an oriented film (hereinafter, referred to as a “biaxially oriented polylactic acid-based film”) is preferably obtained by biaxial stretching. The index of orientation at this time is preferably 3.0 × 10—3 or more in plane orientation ΔΡ. In order to achieve this, it is necessary to stretch at least 1.5 times in the uniaxial direction. This biaxially stretched oriented polylactic acid-based film is stretched biaxially, and then heat-treated while being fixed. As a result, a heat-set biaxially oriented polylactic acid film can be obtained. It is preferable that at least one of the longitudinal and lateral directions of the film has a shrinkage ratio at 80 ° C. of 10% or less. If the shrinkage exceeds 10%, heat shrinks relatively easily, and a problem is likely to occur. For example, as an application of these films, an adhesive is applied on the film surface and bonded to paper, a metal thin film, or other plastic films. Such heat causes the film to shrink, impairing the appearance such as wrinkles, and causing the laminating body to roll easily.

The surface roughness Ra (center line average roughness) of the obtained biaxially oriented polylactic acid-based film is preferably 0.01 <Ra≤0.08. (Ten-point average roughness) is more preferably 2.0 or less. The larger the Ra, the rougher the film surface and the higher the slipperiness. However, if Ra is too large, the film will have poor smoothness. Rz can be used as an index of smoothness. As this value is larger than Ra, the unevenness (roughness) of the film is sparser, and there is no uniformity. As the value approaches Ra, the size of the unevenness is more uniform. The measurement of Ra and Rz can be measured in accordance with JISB0601,

The coefficient of friction of the biaxially oriented polylactic acid film is preferably 0.8 or less in static friction coefficient, more preferably -0.5 or less, and more preferably 0.3 or less. There are two types of friction coefficient: static friction coefficient and dynamic friction coefficient. In general, the smaller the static friction coefficient, the smaller the dynamic friction. The coefficient of static friction is larger than the coefficient of dynamic friction. Films are produced continuously and are usually rolled. At this time, since the films come into contact with each other-If the coefficient of friction of the film is large, it does not slip and cannot be taken up uniformly and uniformly, and it is also a problem in film processing, for example, printing, laminating, and bag making. In some cases, static electricity is generated and productivity may be significantly reduced. Therefore, it is better to satisfy the above requirements by evaluating the coefficient of static friction.

More preferred embodiments of the method for producing a biaxially oriented polylactic acid film according to the present invention are as follows. That is, the polylactic acid-based polymer 10 in which the ratio of L-lactic acid to D-lactic acid is in the range of 100: 0 to 94: 6 or in the range of 6: 94-0: 100. 0 In other words, 0.01 to 120 parts by weight of an inorganic particle having an average particle diameter of 0.1 to 5 μm is blended with respect to parts by weight, and the biaxial direction is stretched. This makes it possible to produce a biaxially oriented polylactic acid film having an average surface roughness Ra of 0.01 <Ra≤0.08. Example

Hereinafter, the present invention will be described in more detail with reference to Examples. It should be noted that the present invention is not limited to the following examples unless the gist of the present invention is exceeded.

The methods for measuring various physical properties and characteristics in the present invention are as follows.

(1) Average particle size

The particle size distribution was measured and calculated by sedimentation balance measurement method, Cole-Yuichi counter measurement method, light scattering method, etc.

(2) Film thickness

Ten-point measurements were made with a dial gauge S M-1201 manufactured by Tec Kokukoku Co., Ltd., and the average value was used as the thickness. The unit is m.

(3) Plane orientation degree

The refractive index (α, β, y) in three orthogonal directions was measured by Abbe refractometer and calculated by the following formula.

△ Ρ = {(α +?) / 2} — (<<< 3 <α)

A: Maximum refractive index in the film plane

β: Refractive index in the direction perpendicular to the film plane α: Refractive index in the thickness direction of the film

The values shown in the table are expressed in 0.001 units and are multiplied by 1000.

(4) Surface roughness

The measurement was performed based on the method described in JISΒ060. Ra (centerline average roughness) and Rz were measured using a surface roughness tester (SE-3F) manufactured by Kosaka Laboratory Co., Ltd.

(Ten point average roughness) was determined. The stylus tip radius of the measuring instrument was 2 zm, the load was 30 mg, the measurement length was 8 mm, and the force-off value was 0.08 mm.

(5) Static friction coefficient According to JISK 712, measurement was made in the machine direction (MD), taking into account the roll of film. The front and back of the film were measured three times each, for a total of six times, and the average was taken.

(6) Heat shrinkage

Cut the film sample in the longitudinal direction (MD) and in the direction perpendicular to it (TD), each with a length of 140 mm (width 10 mm), with a 100 mm line between them, and hot water at 80 ° C. After immersion in the bath for 5 minutes, the dimension between the evaluation lines was measured, and the heat shrinkage was calculated according to the following equation.

Heat shrinkage (%) = [(dimension before shrinkage) one (dimension after shrinkage)] / (dimension before shrinkage) X100

(7) Haze

The measurement was performed according to JIS K 7105. The smaller the value, the higher the transparency.

(8) Comprehensive evaluation

The above properties were combined and evaluated according to the following criteria.

◎: Particularly good

〇: Good

△: Slightly good and can be used as a product

X: Cannot be used as a product.

(Example 1)

Polylactic acid with a molecular weight of about 200,000 with a ratio of L-lactic acid component to D-lactic acid component of 95: 5, and granular silicon dioxide manufactured by Fuji Silicon Chemical Co., Ltd. with an average particle size of about 2.5 m

(Silica) (Product name: Silica 430) After drying 1 part by weight of each to remove water sufficiently, the mixture was put into a φ40 mm co-rotating twin-screw extruder, and about 200 The mixture was melt-mixed at a temperature of ° C, extruded into strands, extruded into pellets with cooling. <The pellets were used as master batches, dried again, and dried again with the above-mentioned polylactic acid. 10%, mixed into a twin-screw extruder with a diameter of 40 mm, extruded into a sheet at a set temperature of 210 ° C, and quenched and solidified by a rotating cooling drum. I got one. The obtained sheet is brought into contact with a hot water circulation type roll while Heated together, 3.0 times at 75 ° C vertically between the peripheral speed difference rolls. The film was stretched 3.0 times at 75 ° C. and then heat-treated at 120 ° C. for about 15 seconds to produce a film having a thickness of 40 mm. The film was wound up by a winder. Observation of the occurrence of wrinkles in the film at this time revealed that a roll sample could be obtained without any particular problems. Table 1 shows the evaluation results of the obtained films.

(Example 2)

A film having a thickness of 40 m was produced in the same manner as in Example 1 except that polylactic acid having a molecular weight of about 180,000 and a ratio of L-lactic acid component to D-lactic acid component of 92: 8 was used. . The winding condition of the film tends to be slightly wrinkled, but it has been used as a product. Table 1 shows the evaluation results of the obtained films.

(Example 3)

Polylactic acid with a molecular weight of about 200,000 with a ratio of L-lactic acid component to D-lactic acid component of 95: 5, and calcium carbonate manufactured by Nitto Powder Chemical Co., Ltd. with an average particle size of about 0.9〃m ( Product name: NS # 250) After drying 50 parts by weight to remove water sufficiently, put it into a φ40 mm co-rotating twin-screw extruder and set it at about 210 ° C. The mixture was melt-mixed, extruded into strands, and cut into pellets while cooling. The pellet was dried again, put into a Φ40 mm co-axial twin screw extruder, set at a temperature of 210 ° C, and then biaxially oriented to a thickness of 40 mm in the same manner as in Example 1. A film was prepared. The film was wound up with a winder. Observation of the wrinkles of the film at this time showed that a roll-shaped sample could be obtained without any particular problem, but the film lacked transparency. Table 1 shows the evaluation results of the obtained films.

(Examples 4 and 5)

A biaxially oriented film having a thickness of 40 m was produced in the same manner as in Example 1 with the number of particles blended as shown in Table 1. However, in Example 4, the heat treatment temperature was set to 50 ° C. or lower, which was lower than the glass transition temperature, to produce a biaxially oriented film that was not substantially thermally fixed. In Example 5, a uniaxially oriented film having a thickness of 60 / m, which was stretched 2.5 times in the vertical direction without longitudinal stretching, was produced. In winding with a winder, Example 4 tended to be good and Example 5 tended to wrinkle slightly. did it. Table 1 shows the evaluation results of the obtained films.

(Example 6)

L Monolactic acid component: D—The ratio of lactic acid component is 9 9: 1 Polylactic acid with a molecular weight of about 220,000 and polybutylene succinate / adipate (manufactured by Showa Kogyo Co., Ltd., trade name: Biono Ile # 3003) and granulated silicon dioxide (silica) manufactured by Fuji Silica Chemical Co., Ltd. with an average particle size of about 2.5 m (trade name: Silicia 430) 0.1 part by weight After drying each of them to remove water sufficiently, they are put into a φ40 mm co-rotating twin-screw extruder, melt-mixed at about 210 ° C, extruded into strands, and cooled. I cut it in a pellet shape while rejecting it. The pellet was dried again and charged into a Φ 40 πι ιη co-rotating twin-screw extruder at a set temperature of 210 ° C. Thereafter, the pellet having a thickness of 40 μm was formed in the same manner as in Example 1. An axially oriented film was produced. Table 1 shows the vertical and horizontal stretching temperatures, stretching ratios, and heat treatment temperatures. The film was taken up by a winder and the wrinkles of the film were observed at this time. As a result, a roll sample could be obtained without any particular problem. The evaluation results of the obtained film are shown in Table 1, (Comparative Example 1).

The same procedure as in Example 1 was repeated except that the average particle size of the granular silicon dioxide (silica) to be blended was changed to 6.0 m (trade name: Silicia 770, manufactured by Fuji Silicon Chemical Co., Ltd.). A biaxially oriented film having a thickness of m was prepared. The film is taken up by a winder. When the degree of wrinkling of the film is observed at this time, the occurrence of wrinkles is remarkable, and the film lacks the flatness and is insufficient as a product. It is determined that there is. Table 2 shows the evaluation results.

(Comparative Example 2)

A biaxially oriented film was prepared in the same manner as in Example 1 except that the particles to be blended were changed to fine particles of titanium dioxide (average particle size: 0.05 m) (trade name: TAF-110, manufactured by Fuji Titanium Co., Ltd.) I got The film is wound up by a winder. Observation of the occurrence of wrinkles on the film at this time reveals that wrinkles are remarkable and the product is judged to be insufficient. Table 2 shows the evaluation results.

(Comparative Example 3)

The number of parts of granular silicon dioxide (silica) having an average particle size of 2.5 μm was A biaxially oriented film was obtained in the same manner as in Example 1 except that the amount was changed to parts by weight. The occurrence of wrinkles in winding is remarkable, and it is judged that the product is insufficient. Table 2 shows the evaluation results.

(Comparative Example 4)

In the same manner as in Example 3 except that the number of parts of calcium carbonate (trade name: NS # 250000) manufactured by Nitto Powder Chemical Co., Ltd. having an average particle size of about 0.9 zm was changed to 140 parts by weight. An attempt was made to produce a biaxially oriented film. However, during production, holes were frequently formed in the film during longitudinal stretching and breakage occurred frequently, and a stable film could not be obtained.

(Comparative Examples 5, 6)

In Comparative Example 5, the stretching temperature and the magnification were changed as shown in Table 1. In Comparative Example 6, the ratio between the L-lactic acid component and the D-lactic acid component was approximately 80:20, and the molecular weight was about 16 A biaxially oriented film was produced in the same manner as in Example 1 except that the polylactic acid was changed to 100,000 and the heat treatment temperature was set to 100 ° C. In each case, the occurrence of wrinkles in winding was remarkable, and it was judged that the product was insufficient. Table 2 shows the evaluation results. Industrial applicability

According to the present invention, since the biaxially oriented aliphatic polyester film has a predetermined surface roughness, the biaxially oriented aliphatic polyester film has good slip and suppresses the meandering and wrinkling of the film.

In addition, since the biaxially oriented aliphatic polyester film has a predetermined composition, it can maintain stiffness, strength, and low heat shrinkage.

table 1

Table 2

Claims

The scope of the claims

1. Biaxial composed of aliphatic polyester mainly composed of polylactic acid polymer, blended with inorganic particles, and having an average roughness Ra of 0.01 and Ra≤0.08 on the film surface Oriented aliphatic polyester film.

2. The average particle size is 0.1 π! 2. The biaxially oriented aliphatic polyester film according to claim 1, wherein 0.01 to 120 parts by weight of inorganic particles of from 5 to 5 m are blended.

3. The biaxially oriented aliphatic polyester film according to claim 1, wherein the ten-point average roughness R z is 2.0 or less.

4. The biaxially oriented aliphatic polyester film according to claim 1, having a coefficient of static friction of 0.8 or less.

Even 5. plane orientation degree delta [rho is rather small 3. 0 X 1 0- ³ a biaxially oriented aliphatic polyester off Irumu according to any one of claims 1 to 4.

6. The biaxially oriented aliphatic polyester-based film according to any one of claims 1 to 5, wherein at least one of the longitudinal direction and the transverse direction has a shrinkage ratio at 80 ° C of 10% or less.

7. The ratio of L-lactic acid and D-lactic acid in the polylactic acid-based polymer is in the range of 100: 0: 94: 6 or 6: 94-0: 100. The biaxially oriented aliphatic polyester-based film according to any one of claims 1 to 6.

8. 100% by weight of polylactic acid-based polymer in which the ratio of L-lactic acid and D-lactic acid is in the range of 100: 0 to 94: 6 or in the range of 6:94 to 0: 100 Parts by weight of inorganic particles having an average particle diameter of 0.1 zm to 5 / m in an amount of from 0.01 to L; 20 parts by weight of L, and biaxially stretched to obtain an average surface. A method for producing a biaxially oriented aliphatic polyester film having a roughness Ra of 0.01 <Ra≤0.08.