JP2000103006A - Aliphatic polyester film having gas barrier property - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aliphatic polyester film having gas barrier properties, which is excellent in transparency and flexural resistance effective as a general packaging film, and excellent in running property at the time of film processing and gas barrier properties after a running of the film is contact with parts of film processing devices. SOLUTION: A base film contains, as a main component, an aliphatic polyester wherein a repeating unit is represented by a formula: -O-CHR-CO-, wherein R is a hydrogen or 1-3C alkyl group. The gas barrier film is formed by laminating a silicon oxide-based deposited layer on at least one side of the base film. A specific gravity of the deposited layer is 1.80-2.20 g/cm3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a gas barrier aliphatic polyester film, and particularly to the transparency and resistance properties which are important requirements for packaging films for fresh foods, processed foods, pharmaceuticals, medical equipment, electronic parts and the like. The present invention relates to an aliphatic polyester film having excellent flexibility, running property during film processing, and excellent gas barrier properties after running while the film is in contact with parts of a film processing apparatus.

[0002]

2. Description of the Related Art Conventionally, various plastics such as polyethylene, polypropylene, polyethylene terephthalate, polyolefins represented by nylon 6, aromatic polyesters, polyamides and the like have been used for films for packaging various products including foods. . These packaging films are to be collected after use and disposed of by incineration or burying in soil. However, it is well known that the collection requires a great deal of labor, so that it is actually left uncollected and causes various problems such as environmental pollution. In addition, in the case of incineration, the thermal power is too strong, the furnace is severely damaged, and a large amount of fuel is required, which increases the cost. On the other hand, when buried in soil, there is a problem that the waste does not have biodegradability and remains semipermanently in the soil. Under these circumstances, there has been an increasing demand for various packaging films having good biodegradability.

[0003] Therefore, in order to impart biodegradability to the above polyethylene and the like, various studies have been made on blending a biodegradable component such as starch. Furthermore, a method of imparting photodegradability or a method of blending a biodegradable component of starch with photodegradable polyethylene and the like have been studied, and are attracting attention as a solution to the above-mentioned problem. However, in these methods, the starch component is biodegradable and thus decomposed by microorganisms in the soil.
The polymer parts other than starch are not decomposed. Therefore, it is not a fundamental solution to the above problem.

[0004] From these facts, with the increasing public awareness of environmental protection in recent years, when plastic products are generally disposed of in the natural environment, they are decomposed and disappear over time, adversely affecting the natural environment. There is a demand for a plastic product that does not affect the environment.

[0005] As a fundamental solution to the above problem, various biodegradable polymer materials in which the polymer itself has biodegradability have been studied. Above all, polylactic acid is easily degraded when rejected in the natural environment.For example, polylactic acid film has the advantage that it is naturally hydrolyzed in soil and then becomes a harmless degradation product by microorganisms. More and more have been developed. Specifically, for example, a polylactic acid film is used as a molded product for medicine (Japanese Patent Publication No. 41-273).
No. 4, JP-B-63-68155, etc.), and its application as a basic material of a biodegradable general-purpose material for disposable use other than pharmaceutical use has been variously studied.

Above all, a biaxially stretched film using a polylactic acid-based polymer has transparency and biodegradability and has excellent mechanical properties equivalent to a general-purpose film. Applications are expected for a wide range of applications. However, since the polylactic acid film has a relatively high gas permeability, when this film is used as a food packaging material, there is a serious disadvantage that the shelf life of the packaged food product is shortened. Japanese Patent Laid-Open Publication No. 8-505825 discloses a solution to this problem, in which a metal such as aluminum is laminated as a vapor-deposited film on the surface thereof. However, the film obtained by this method is inferior in transparency, which is a characteristic particularly required for food packaging, and there is a problem that the application to which the film is applied is limited.

In order to solve this problem, a polylactic acid-based gas barrier film in which a vapor-deposited layer using a transparent inorganic oxide is laminated is disclosed in JP-A-10-138433 and JP-A-10-24518. And so on. However, in these gas barrier films,
Although the transparency is improved, the running property during film processing and the gas barrier property of the film after running while contacting the parts of the film processing apparatus are not sufficient.

[0008]

DISCLOSURE OF THE INVENTION The present invention solves the above problems of conventional biodegradable films and biodegradable laminated films, and provides transparency effective as a general packaging film.
An object of the present invention is to provide a gas-blocking aliphatic polyester film which is excellent in bending resistance, running property during film processing, and gas blocking property after the film runs while contacting parts of the film processing apparatus.

[0009]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above situation, and a gas barrier aliphatic polyester film capable of solving the above-mentioned problems is as follows. It is.

That is, the first invention of the present invention is a
When the repeating unit has the general formula -O-CHR-CO- (R is hydrogen or
Aliphatic polyester which is an alkyl group having 1 to 3 carbon atoms)
Acid is applied to at least one surface of the base film mainly containing
A gas barrier film having a silicon oxide-based deposition layer
The specific gravity of the vapor deposition layer is 1.80 to 2.20 g / cm ^Three
A gas barrier aliphatic polyester characterized by the following:
Film.

According to a second aspect of the present invention, the aliphatic polyester film has a three-dimensional average gradient (S △ a) of at least 0.005 to 0.04 on at least a vapor deposition surface, and a projection height of 1.10 on the film surface. 1 mm ² protrusions of 89 μm or more
The gas barrier aliphatic polyester film according to the first invention, wherein the aliphatic polyester film does not substantially exist in the range of.

In a third aspect, the base film has a thickness of 10 to 250 μm, and the thickness of the vapor deposition layer is 10 to 500 μm.
0. The gas barrier aliphatic polyester film according to the first or second aspect, wherein the angle is 0 °.

A fourth invention is the gas barrier aliphatic polyester film according to any one of the first to third inventions, wherein the aliphatic polyester is polylactic acid.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The aliphatic polyester used in the present invention has a main repeating unit of the general formula -O-
A polyester which is CHR-CO- (R is hydrogen or an alkyl group having 1 to 3 carbon atoms).

Here, all the repeating units of the aliphatic polyester are preferably represented by the above general formula.
If necessary, a unit other than the repeating unit represented by the above general formula may be contained as long as the performance as the aliphatic polyester is not impaired. Specifically, for example, 70 mol% or more of the repeating units in the molecule are preferably the repeating units represented by the above general formula, more preferably 80 mol% or more, and still more preferably 90 mol% or more. Mol% or more, particularly preferably 95 mol% or more.

However, the aromatic polyester usually does not contain an aromatic component. If necessary, an aromatic component may be employed as long as the performance as the aliphatic polyester is not impaired.In that case, the ratio of the repeating unit containing the aromatic structure may be, of the repeating units in the molecule. 1
It is preferably 0 mol% or less, more preferably
It is at most 5 mol%, more preferably at most 3 mol%.

Specific examples of the aliphatic polyester include, but are not limited to, polylactic acid, polyglycolic acid, and poly (2-oxybutyric acid). Among them, polylactic acid is most preferable in terms of performance and price.
Further, the aliphatic polyester may be a homopolymer or a copolymer obtained by copolymerizing a plurality of types of repeating components selected from the above general formula. Further, the aliphatic polyester may be a single polymer or a mixture of a plurality of aliphatic polyesters.

When an asymmetric carbon is present in the constituent carbon atoms of the aliphatic polyester, optical isomers such as L-form, DL-form and D-form can exist, and any of them can be employed. Mixtures of these isomers can also be employed.

Further, other polymer materials may be mixed with the aliphatic polyester as long as the effects of the present invention are not impaired. When another polymer material is mixed, preferably, the aliphatic polyester is 70% by weight or more of the total weight of the aliphatic polyester and the other polymer material, and more preferably 80% by weight or more. , More preferably 90% by weight, particularly preferably 95% by weight or more. The aliphatic polyester described above (hereinafter, referred to as
Sometimes simply referred to as “polymer”. ) Is produced by a known method, for example, a method such as ring-opening polymerization of the corresponding dehydrated cyclic ester compound of α-oxyacid, and becomes the base film of the present invention.

The weight average molecular weight of the aliphatic polyester used in the present invention is preferably 5,000 to 500,000. More preferably, it is 1 to 500,000. More preferably, it is 40,000 to 300,000, particularly preferably 50 to 300,000. If the weight average molecular weight is too small, the physical properties of the obtained film are liable to decrease, and the biodegradation rate tends to be too high, which is not preferable. The weight average molecular weight is preferably 10,000 or more in order to ensure sufficient extrudability from a film-forming machine during film production and stretchability with a biaxial stretching machine. On the other hand, when the weight average molecular weight is too high, there is a problem that melt extrusion of the aliphatic polyester becomes difficult.

The aliphatic polyester may contain a known additive, if necessary. For example, a lubricant, an antiblocking agent, a heat stabilizer, an antioxidant, an antistatic agent, a lightfast agent, an impact resistance improver, a crystal nucleating agent,
A coloring inhibitor, a pigment, a dye, an ultraviolet absorber, a release agent, an antibacterial agent, a flame retardant, or the like may be contained. For example, anionic surfactants such as potassium lauryl phosphate, cationic surfactants such as quaternary ammonium salts, ethylene oxide addition of aliphatic higher alcohols and higher fatty acids, if necessary, in consideration of antistatic properties and the like. Nonionic surfactants such as products, polyalkylene glycols such as polyethylene glycol, polyethylene glycol / polypropylene glycol block copolymers, and silicone oils such as dimethyl polysiloxane, polyether-modified silicone oil, and higher alkoxy-modified silicone oil. Alternatively, two or more kinds can be contained. Further, the aliphatic polyester may be appropriately mixed with one or more of polymers such as polyamino acids, talc, calcium carbonate, calcium sulfate, calcium chloride, inorganic substances such as silicon oxide, starch, protein, food additives and the like. It is possible to change various mechanical properties, biodegradation properties, and the like. However, the aliphatic polyester film of the present invention,
It is necessary that the film on which the deposited layer of the oxide is laminated is transparent and the contents are visible. Therefore, it is necessary to consider the type of the additive so as to have high transparency even before the deposition layer is laminated.

For example, inorganic particles, organic salt particles or heat-resistant polymer particles, which are particles inactive with respect to an aliphatic polyester, are improved in order to improve the film handling properties such as slipperiness, running property and winding property. Group polyester.

Examples of the inorganic particles include metal oxides such as silica, titanium dioxide, aluminum oxide, zirconium oxide and kaolinite, calcium carbonate, magnesium carbonate, barium carbonate, calcium phosphate, magnesium phosphate, lithium phosphate, and sulfuric acid. And salts of metals such as barium and lithium fluoride.

In particular, in order to obtain a film having excellent transparency while maintaining good handling properties, it is preferable to use silica which is a particle having a refractive index close to that of the aliphatic polyester. Agglomerated silica particles, crushed silica, and glass filler are particularly preferred.

Examples of the organic salt particles include calcium oxalate or calcium, barium, zinc, manganese,
Alternatively, a terephthalate such as magnesium may be used.

Examples of the heat-resistant polymer particles include homo- or copolymers of vinyl monomers such as divinylbenzene, styrene, acrylic acid, methacrylic acid and acrylic acid. Specifically, for example, crosslinked polymer particles such as crosslinked polystyrene resin, crosslinked acrylic resin, crosslinked polyester resin, and silicone resin, polytetrafluoroethylene, benzoguanamine resin, thermosetting epoxy resin, unsaturated polyester resin, thermosetting Heat-resistant organic particles such as a urea resin and a thermosetting phenol resin are exemplified.

Any one of these lubricant particles may be used alone, or two or more thereof may be used in combination. The average particle diameter of the lubricant particles used is 0.01 to 3.0 μm. It is preferable that the thickness be 0.05 to 2.5 μm. The content thereof is 0.005 to 0.005 in the film composition in order to achieve both transparency and slipperiness of the film.
2.0% by weight, preferably 0.01 to
It is preferably 1.0% by weight.

In order to achieve both transparency and slipperiness of the film, it is preferable to use two or more kinds of lubricant particles in combination. In particular, lubricant particles that deform during film formation (eg, cross-linked polymer particles such as cross-linked polystyrene and cross-linked acryl with a low degree of cross-linking, and silica that is an aggregate of primary particles) and usually do not deform during film formation Of lubricant particles are preferably combined.

The method of adding the lubricant particles to the aliphatic polyester is not particularly limited, and any known method can be used. Specifically, for example, when polylactic acid is used as the aliphatic polyester, before polymerizing lactide, a method of dispersing lubricant particles in molten lactide, and dispersing the lubricant during the polymerization reaction of lactide There are methods.

The aliphatic polyester composition for a film thus prepared is formed into a film by a conventionally known method. Preferably, the film is further stretched after molding. Specifically, a biaxial stretching method such as a uniaxial stretching method in which the film is stretched in a longitudinal direction or a transverse direction, an inflation method, a simultaneous biaxial stretching method, or a sequential biaxial stretching method is used. As the sequential biaxial stretching method, for example, longitudinal stretching and transverse stretching may be performed in order, or transverse stretching and longitudinal stretching may be performed in order. Further, a stretching method such as a horizontal / longitudinal / longitudinal stretching method, a vertical / horizontal / longitudinal stretching method, a vertical / longitudinal / horizontal stretching method can be applied. Further, if necessary, a heat setting treatment, a vertical relaxation treatment, a horizontal relaxation treatment, or the like may be performed. More preferably, it is heat-set after biaxial stretching.

For example, when an aliphatic polyester film is produced by an extrusion method, a known T-die method,
An inflation method or the like can be applied, and an unstretched film can be obtained by these methods. The extrusion temperature is from the melting temperature (Tm) of the aliphatic polyester used to Tm + 7.
0 ° C. range, more preferably Tm + 20 to Tm + 50
It is in the range of ° C. If the extrusion temperature is too low, an excessive load is applied to the extruder, which makes it difficult to perform stable extrusion. Conversely, if the extrusion temperature is too high, the aliphatic polyester tends to decompose, which is not preferable. As the die of the extruder used for producing the aliphatic polyester film, a die having an annular or linear slit can be used. As for the temperature of the die, the same temperature as the extrusion temperature is applied.

In the biaxial stretching of the unstretched film made of the aliphatic polyester, the uniaxial stretching and the second axial stretching may be performed sequentially or simultaneously. The stretching temperature ranges from Tg (glass transition point) to Tg + 50 of the aliphatic polyester used.
C. is preferred. More preferably, Tg + 10 to T
g + 40 ° C. If the stretching temperature is too low, stretching is difficult, while if it is too high, the thickness uniformity or the mechanical strength of the obtained film decreases, which is not preferable.

The stretching in the vertical and horizontal directions may be performed in one step or in multiple steps, but it is ultimately at least three times, more preferably 3.5 times or more in each stretching direction. -9 times or more in horizontal area magnification, more preferably 1
Stretching at least two times is preferable in terms of thickness uniformity and mechanical properties. If the longitudinal and transverse stretching ratios are each 3 times or less and the area magnification is 9 times or less, it becomes difficult to obtain a film having good thickness uniformity, and it is difficult to obtain sufficient improvement in physical properties such as mechanical strength. . The thickness of the base film mainly composed of an aliphatic polyester is preferably from 10 to 250 μm, more preferably from 12 to 250 μm.

In the biaxially stretched film, the longitudinal direction means the longitudinal stretching direction, and the width direction means the transverse stretching direction. The upper limit of the stretching ratio is not particularly limited. However, it is preferable that the film is controlled so as not to break during stretching.

The aliphatic polyester film may be formed into a multilayer film by providing a co-extrusion step with another resin or a coating step during the production process. In addition, the aliphatic polyester film, depending on the application,
A corona discharge treatment, a coating treatment, a plasma treatment or a flame treatment may be performed for the purpose of improving the surface energy or improving the adhesiveness or wettability. In particular, before laminating an oxide vapor deposition layer on the aliphatic polyester film, the above-mentioned treatment may be performed in advance in order to enhance the adhesion between the film and the oxide vapor deposition layer.

The formation of the oxide deposited layer is performed by a vacuum deposition method,
Physical vapor deposition methods such as sputtering and ion plate methods,
Alternatively, a chemical vapor deposition method such as CVD is appropriately used. The heating method employed at this time includes resistance heating, induction heating, electron beam heating and the like. As a reaction gas, oxygen, nitrogen, hydrogen, argon, carbon dioxide, water vapor, or the like may be introduced, or a reactive vapor deposition method using means such as ozone addition or ion assist may be employed. Further, it is also possible to apply a bias to the aliphatic polyester film as the base material, and to change evaporation conditions such as heating and cooling of the aliphatic polyester film at the time of evaporation depending on the evaporation method. Such deposition material, reaction gas, aliphatic polyester film bias, and heating and cooling conditions of the aliphatic polyester film are also adjusted to appropriate conditions when the sputtering method or the CDV method is employed. It is possible to change. Before or during the deposition of the deposition material, the surface of the aliphatic polyester film to be deposited is subjected to corona discharge treatment, flame treatment, low-temperature plasma treatment, glow discharge treatment, reverse sputtering treatment, surface roughening treatment, etc. to adhere the deposited layer It is also effective to further increase the strength.

The silicon oxide-based deposition layer is made of Si, SiO, S
It is composed of iO _{2 and the} like, and these ratios differ depending on the preparation conditions.

In the present specification, the specific gravity refers to a ratio of the mass of a substance occupying a certain volume at a certain temperature to the mass of a standard substance having the same volume (water at 4 ° C.). The specific gravity is usually measured by measuring the mass and volume of the object and calculating the ratio of the same volume of water at 4 ° C.
Measurement of volume is difficult. So, first remove the vapor deposition layer from the aliphatic polyester film laminated vapor deposition layer,
Alternatively, it is desirable to use a specific gravity measurement method described in JIS-K7112 after dissolving only an aliphatic polyester film from a film in which a vapor deposition layer is laminated to form a single film of the vapor deposition layer. For example, in the flotation method,
A sample is immersed in a solution having a known specific gravity, and the specific gravity of the vapor-deposited layer can be measured from its floating state. Solutions with known specific gravity include carbon tetrachloride and bromoform,
Alternatively, a mixed solution such as methylene iodide can be used. The specific gravity value can also be measured by a density gradient tube method in which a single film is immersed in a solution having a continuous density gradient.

The value of the specific gravity of the silicon oxide-based deposition layer is 1.80.
〜2.20 g / cm ³ , preferably 1.90 to 2.15 g / cm ³ . If the specific gravity of the vapor deposition layer is too small, the structure of the silicon oxide vapor deposition layer becomes coarse, and sufficient gas barrier properties cannot be obtained. If the specific gravity of the vapor-deposited layer is too large, although the initial gas barrier properties after film formation are excellent, the film becomes too hard and the bending resistance is reduced. For example, the gas barrier property after mechanical fatigue due to repeated bending or the like is greatly reduced, and the usefulness as a gas barrier film is reduced. By laminating the above-mentioned vapor-deposited layer on an aliphatic polyester film, a gas barrier film having excellent bending resistance can be obtained.

In a preferred embodiment, one feature is that attention is paid to the surface condition of the aliphatic polyester film. That is, in a preferred embodiment, the aliphatic polyester film has a three-dimensional average inclination gradient (S △ a) of at least 0.005 to 0.04 on at least the vapor deposition surface, thereby having excellent running properties during film processing, and A film excellent in gas barrier properties after processing can be obtained. S △
If a is less than 0.005, the running property during film processing becomes poor, the film surface after running becomes extremely rough, and the gas barrier property is reduced. On the other hand, when S０．０a is larger than 0.04, transparency and abrasion resistance tend to be poor, which leads to a decrease in film quality.

In a further preferred embodiment, the protrusion height is 1.
There are substantially no protrusions of 89 μm or more within a range of 1 mm ² on the aliphatic polyester film surface. 1.89μ
If there is a protrusion having a height of m or more, the transparency tends to be poor, and the abrasion resistance tends to decrease, so that white powder is likely to occur.

The thickness of the deposited layer is preferably from 10 to 5000 °. If the film thickness is too thin, it is difficult to obtain a sufficient gas barrier property. If the film thickness is too large, the bending resistance tends to decrease, the production cost increases, and the gas barrier property is improved. Is not practical because it saturates.

The aliphatic polyester film of the present invention, on which the vapor-deposited layer is laminated, is colorless and transparent, and the packaged contents must be visible. Therefore, the haze (haze value) of the laminated aliphatic polyester film is low. Is preferred. Specifically, 5% or less is preferable. It should be noted that other layers may be further formed on the aliphatic polyester film on which the vapor-deposited layers are laminated as long as the object of the present invention is not impaired.

Further, a resin layer having heat sealability, that is, a sealant layer may be laminated on the vapor-deposited layer side of the aliphatic polyester film. A polyolefin resin is preferably used for the resin layer having heat sealing properties. Specific examples include polypropylene and polyethylene.

[0045]

EXAMPLES Hereinafter, the contents and effects of the present invention will be described specifically with reference to examples and comparative examples, but the present invention is not limited to these examples. First, methods for evaluating physical properties in the following examples and comparative examples will be described.

(Haze value) The haze value was measured using 300A manufactured by Nippon Seimitsu Kogaku Co., Ltd. according to JIS-K6714. The unit is%.

(Gas barrier property) The amount of oxygen permeation is measured by an oxygen permeability measuring device (“OX-TRAN 10 / 50A”) Mod.
The measured value was 0% humidity, 25 ° C. temperature, and purged for 2 days. Unit is cc / m ² · 24hr · a
tm. In addition, the water vapor transmission rate is measured using a water vapor transmission rate measuring device (“PERMATRAN” Modern Control).
ols) at a temperature of 40 ° C., a humidity of 90%, and a two-day purge. The unit is g / m ² · 24 hr.

(Oxygen permeation amount after running the film) The vapor-deposited layer surface of the laminated film was placed on a metal guide roll at 5 kg / cm.
And was run at 250 m / min. The oxygen permeation amount of the laminated film after the guide roll was rubbed was measured by the above method.

(Oxygen permeability after bending fatigue) The bending fatigue of the film was performed using a so-called Gelboflex tester (manufactured by Tester Sangyo Co., Ltd.). The condition is 112 inch × 8 inch with (MIL-B131H).
Was made into a cylindrical shape having a diameter of 3 (１ ／) inch, the both ends were held, the initial holding interval was 7 inches, and a twist of 400 degrees was applied at a stroke of 3 (１ ／) inches. The reciprocating motion of this operation was repeated at a speed of 40 times / min at 20 ° C. and a relative humidity of 65%. After fatigue, the amount of oxygen permeation was measured.

(Three-dimensional average inclination gradient S △ a) Using a stylus type three-dimensional surface roughness meter (SE-3AK, manufactured by Kosaka Laboratory Co., Ltd.), the film surface was measured with a needle radius of 2 μm and a load of 30.
Under a condition of mg, the measurement was performed at a cutoff value of 0.25 mm in the longitudinal direction of the film and a needle speed of 0.1 mm / sec over a measurement length of 1 mm. Measurement data of 2 μm
The data was divided into data of 500 points at a pitch, and the height of each point was taken into a three-dimensional roughness analyzer (SPA-11). The same operation is continuously performed 150 times at 2 μm intervals in the width direction of the film, that is, 0.3 mm in the width direction of the film.
And a quantization width of 0.00312
Data was captured at μm. Next, S △ a was determined using an analyzer. Here, S △ a means a three-dimensional average gradient of the entire film surface, and is defined as follows.

The cross-sectional area and the number of projecting portions of the film at each level horizontal to the center plane are obtained, and the average area of the cross section of the projecting portion at each level is calculated and converted into an average circle radius.
The ratio (gradient) of the change of the average circle radius to the change of the height is determined on the cutting plane of each level, and the respective values are averaged to obtain SΔa. Here, SΔa is, specifically, the height of a predetermined number of measurement points spaced at regular intervals by the stylus-type three-dimensional surface roughness meter, and these measured values are used as the three-dimensional surface roughness. Means the value obtained by taking it into the analyzer. More specifically, the obtained surface roughness curve is approximated by a sine curve, the data is combined to obtain three-dimensional data, and the inclination of the entire surface is determined from the number and height of the projections with the center plane as a reference plane. Calculated. An orthogonal coordinate system consisting of an X axis and a Y axis is placed on the center plane, an axis orthogonal to the center plane is set as a Z axis, and a length Lx in the X axis direction, a length Ly in the Y axis direction Ly, and an area Lx × Ly are set on the center plane. = S
A portion of _M is extracted, and S △ a is represented by the following equation from the extracted portion.

[0052]

(Equation 1)

Here, Z = f (x, y) is the height Z of the film surface at the position (x, y) on the rectangular coordinate axis.
Lx = 500 and Ly = 150.

(Number of protrusions on the film surface) Aluminum film was deposited on the film surface under vacuum, and a filter having a wavelength of 0.54 μm was attached to a two-beam interference microscope. the number of rings or equivalent) more than the protrusion height 1.89μm was measured over 1.3 mm ^2, it was determined as the number per unit area (mm ^2).

Example 1, Comparative Example 1 L-lactide 10
With respect to 0 parts by weight, 0.03 parts by weight of tin octylate as a catalyst is charged into a reaction vessel, and the reaction is carried out at a temperature of 190 ° C. for 1 hour. After the completion of the reaction, the obtained reaction system is depressurized to remain. L-lactide was distilled off to obtain polylactic acid. The reduced viscosity of the obtained polylactic acid was 1.8 dl / g.

The polylactic acid was vacuum-dried in a usual manner at 110 ° C. for 4 hours, and then melt-extruded into a sheet at a resin temperature of 210 ° C. using an extruder equipped with a T-die and having a diameter of 30 mm. And an unstretched film having a thickness of about 300 μm was obtained. Then, it was immediately stretched 3.2 times in the longitudinal direction at 75 ° C. by a roll stretching machine, and further stretched 4 times in the transverse direction at 100 ° C. by a tenter stretching machine. Next, after heat-setting at 150 ° C. while relaxing 6% in the horizontal direction, corona discharge treatment was performed to obtain a biaxially stretched film having a thickness of 25 μm. An evaporation film was laminated on the obtained biaxially stretched film subjected to the corona discharge treatment by using an electron beam heating type vacuum evaporation apparatus, using Si and SiO ₂ as an evaporation material.
An electron gun was used as a heating source, the crucible was divided into two parts without mixing, and the materials were heated in a time-division manner. Further, by adjusting the emission current and the heating ratio of the electron gun, vapor deposition layers having various compositions were obtained. After dissolving the resin layer of the laminated film thus obtained, the specific gravity of the silicon oxide-based vapor-deposited layer was measured by a flotation method.
The obtained results are shown in Table 1 for Example 1 and Table 2 for Comparative Example 1.

(Example 2, Comparative Example 2) Before the start of polymer polymerization, aggregated silica particles having an average particle diameter of 1.8 μm (SYLY manufactured by Fuji Silysia Chemical Ltd.) were used as lubricant particles.
SIA350) was prepared in the form of a slurry dispersed in L-lactide in the same manner as in Example 1, except that it was added in various amounts. Table 3 shows the obtained results. Table 3 shows the content of the lubricant particles with respect to the produced polylactic acid.

Comparative Example 3 Before the start of polymer polymerization, spherical silica particles having an average particle diameter of 5.8 μm (AMT-Silica # 500 manufactured by Mizusawa Chemical Industry Co., Ltd.) were used as lubricant particles.
B) in the form of a slurry dispersed in L-lactide,
Except that various amounts were added, a vapor-deposited layered film was produced by the method described in Example 1. Table 3 shows the obtained results. Table 3 shows the content of the lubricant particles with respect to the produced polylactic acid.

[0059]

[Table 1]

[0060]

[Table 2]

[0061]

[Table 3]

[0062]

The gas-blocking aliphatic polyester film of the present invention has transparency and bending resistance, running property during film processing, and gas-blocking property after running while contacting parts of a film processing apparatus. And is extremely useful as a film for general packaging.

Continued on front page (72) Inventor Tadashi Okuhira 2-1-1 Katata, Otsu City, Shiga Prefecture Toyobo Co., Ltd. Research Laboratory

Claims (4)

[Claims] (1) a main repeating unit represented by the general formula -O-CH
R-CO- (R is hydrogen or an alkyl group having 1 to 3 carbon atoms)
Is a gas barrier film in which a silicon oxide-based vapor-deposited layer is laminated on at least one surface of a base film mainly composed of an aliphatic polyester, wherein the specific gravity of the vapor-deposited layer is 1.
A gas barrier aliphatic polyester film having a weight of 80 to 2.20 g / cm ³ . 2. A projection having a three-dimensional average gradient (S △ a) of at least 0.005 to 0.04 on at least a deposition surface of the aliphatic polyester film and a projection height of 1.89 μm or more on the film surface. Is substantially absent within a range of 1 mm ² . 3. The thickness of the base film is 10 to 250.
3. The gas-blocking aliphatic polyester film according to claim 1 or 2, wherein the thickness of the vapor-deposited layer is 10 to 5000 °. 4. The gas-blocking aliphatic polyester film according to claim 1, wherein the aliphatic polyester is polylactic acid.