JP2003113259A - Biaxially oriented polyester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biaxially oriented polyester film having pinhole-resistant characteristics which a biaxially oriented nylon film has and also having good moldability which a conventional biaxially oriented polyester film and the biaxially oriented nylon film have not. SOLUTION: This biaxially oriented polyester film comprises a resin component composed of (A) 55-95 wt.% resin having 240-265 deg.C melting point and comprising >=90 wt.% polyester component composed of ethylene terephthalate and/or ethylene naphthalate and (B) 5-45 wt.% resin having 185-235 deg.C melting point and comprising >=70 wt.% polyester component, and the polyester film has properties comprising (1) >=200 MPa loss modulus (E") at a peak temperature of β disperse and (2) >=140 MPa breaking strength of the film or (1') >=55% recovery factor of deformation of the film after 20% pulling at 0 deg.C and (2) >=140 MPa breaking strength of the film.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a biaxially oriented polyester film, and more particularly to a biaxially oriented polyester film having excellent pinhole resistance and moldability.

[0002]

2. Description of the Related Art Generally, a biaxially oriented polyester film is excellent in many points such as mechanical strength, thermal characteristics and humidity characteristics, and is widely used as a magnetic recording material, a packaging material and the like. However, the biaxially oriented polyester film is inferior in flexibility and pinhole resistance because it is a strong film, and biaxially stretched nylon film is often used in applications where those properties are important.

Further, since the biaxially oriented polyester film has poor moldability, it is rarely used in molding applications. Therefore, in order to impart moldability to the biaxially oriented polyester film, for example, JP-A-3-67 is used.
Japanese Patent No. 629 describes a method of copolymerizing polyester.

On the other hand, the biaxially stretched nylon film has a problem in that it has a large hygroscopicity and a large coefficient of humidity expansion, and has a problem that it is difficult to handle because of a large change in physical properties over time. Further, the biaxially stretched nylon film has a problem that it has poor elongation and poor moldability. On the other hand, the biaxially oriented polyester film has very low hygroscopicity and humidity expansion coefficient, and has no problem in humidity characteristics.

Further, the method of introducing a copolymerization component into polyester as disclosed in JP-A-3-67629 improves the moldability, but does not provide the effect of pinhole resistance, unlike the biaxially stretched nylon film.

[0006]

The object of the present invention is to provide a biaxially oriented polyester film and a biaxially oriented nylon film, which have pinhole-proof properties like those of a biaxially oriented nylon film, which are not found in the original biaxially oriented polyester film. An object of the present invention is to provide a biaxially oriented polyester film having a moldability which is not found in the film.

[0007]

In order to solve the above-mentioned problems, the biaxially oriented polyester film of the present invention mainly has any of the following constitutions. That is, a resin component is the following (A) and (B), and has the following characteristics (1) and (2), (A) melting point 240-265 ° C. And 90% by weight or more of the resin content of a polyester component composed of ethylene terephthalate and / or ethylene naphthalate 5
5 to 95% by weight (B) Resin content of which melting point is 185 to 235 ° C. and 70% by weight or more is polyester component 5 to 45% by weight (1) Loss elastic modulus (E ") at peak temperature of β dispersion Two
00 MPa or more (2) The breaking strength of the film is 140 MPa or more, or the resin components are the following (A) and (B),
A biaxially oriented polyester film having the following properties (1) 'and (2). (A) Resin content 5 consisting of a polyester component having a melting point of 240 to 265 ° C. and 90% by weight or more of ethylene terephthalate and / or ethylene naphthalate
5 to 95% by weight (B) Melting point of 185 to 235 ° C. and resin content of 70% by weight or more consisting of polyester component 5 to 45% by weight (1) ′ Deformation recovery rate after 20% tension of film at 0 ° C. 55% or more (2) Breaking strength of the film is 140 MPa or more Further, in the biaxially oriented polyester film of the present invention, the melting point is 140 to 230 ° C. and the polyether unit is 20.
˜85% by weight of copolymerized modified polybutylene terephthalate (hereinafter referred to as modified PBT) in an amount of 1 to 20% by weight, a peak temperature of β dispersion, and a loss elastic modulus (E ″) at half the peak temperature. The absolute value of the difference from the value temperature (high temperature side) is 30 ° C or higher, and the Young's modulus is 2.5 to 4.0G
Pa, the total breaking elongation in the longitudinal direction and the width direction is 250% or more, and the plane orientation coefficient is 0.10 to 0.
17, the heat shrinkage rate at 30 minutes at 150 ° C is 5%
The following are included as preferable embodiments.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Polyesters (A) and (B) constituting the biaxially oriented polyester film of the present invention are generic terms for polymers having ester bonds as main bonds in the main chain. It can be obtained by subjecting a dicarboxylic acid component and a glycol component to a polycondensation reaction.

As the dicarboxylic acid component used here, in addition to terephthalic acid and naphthalenedicarboxylic acid, for example, isophthalic acid, diphenyldicarboxylic acid, diphenylsulfonedicarboxylic acid, diphenoxyethanedicarboxylic acid, 5-sodiumsulfoisophthalic acid, phthalic acid. Such as aromatic dicarboxylic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, dimer acid, maleic acid, fumaric acid and other aliphatic dicarboxylic acids, cyclohexyne dicarboxylic acid and other alicyclic dicarboxylic acids, p-oxybenzoic acid An oxycarboxylic acid such as an acid can be used.

As the glycol component, in addition to ethylene glycol, for example, aliphatic glycols such as propanediol, butanediol, pentanediol, hexanediol and neopentyl glycol, alicyclic glycols such as cyclohexanedimethanol, bisphenol A and bisphenol. Aromatic glycols such as S, polyoxyalkylene glycols such as diethylene glycol, polyethylene glycol and polypropylene glycol can be used.

Two or more kinds of these dicarboxylic acid components and glycol components may be used in combination.

As long as the effects of the present invention are not impaired,
For example, trimellitic acid, trimesic acid, trimethylo-
It is also possible to copolymerize a polyfunctional compound such as rupropane.

The modified PBT can be obtained by melt-kneading the polybutylene terephthalate obtained by the polycondensation reaction described above and the polyether in an extruder, and the polyether is added in the polymerization step of the polybutylene terephthalate. It can be obtained by polycondensation. Here, the polyether is a polyoxyalkylene glycol such as polyethylene glycol, polypropylene glycol or polytetramethylene glycol, and polyethylene terephthalate may be mixed with the polyether as long as the effect of the present invention is not impaired. . The proportion of block copolymerization of PBT with polyether is preferably 20 to 85% by weight, more preferably 30 to 75% by weight, and particularly preferably 40 to 65% by weight.

By block-copolymerizing the polyester with another polymer, particularly a linear polyether, a segment having a small rotational hindrance (soft segment) is formed in the molecular chain. The impact from the outside, the impact due to bending, etc. are absorbed by the soft segment in the molecular chain, resulting in excellent impact resistance and flexibility.

Polyester (A) has a melting point of 240-26.
It is necessary to be 5 ° C, preferably 245 ° C to 2 ° C.
It is 60 ° C. If the temperature is less than 240 ° C, the heat resistance is insufficient, and 26
If it exceeds 5 ° C, the elongation is lowered and the impact resistance is lowered, which is not preferable.

Polyester (B) has a melting point of 185 to 23.
It is necessary to be 5 ° C., preferably 190 to 23
It is 0 ° C. If it is lower than 185 ° C., the heat resistance is insufficient and the film is inferior in thermal dimensional stability. If it exceeds 235 ° C., the elongation is lowered and the impact resistance is lowered, which is not preferable.

The melting point of the modified PBT is preferably 140 to 230 ° C, more preferably 160 to 210 ° C.
Particularly preferably, it is 160 to 190 ° C. Since the modified PBT is preferably dispersed in an amorphous state from the viewpoint of bending resistance, it is preferable that the melting point be lower than the heat treatment temperature performed after biaxial stretching.

The polyester film of the present invention contains 55 to 95% by weight of polyester (A) and polyester (B).
Should be 5 to 45% by weight. The polyester (A) is preferably 60 to 90% by weight, particularly preferably 65 to 85% by weight, and the polyester (B) is preferably 10 to 40% by weight, particularly preferably 15 to 35%. If the polyester (A) is less than 55% by weight or the polyester (B) exceeds 45% by weight, mechanical strength,
Performances such as dimensional stability and heat resistance are deteriorated, and the moldability, which is one of the objects of the present invention, is deteriorated.
Is over 95% by weight, or polyester (B) is 5
If it is less than 10% by weight, the pinhole resistance, which is one of the objects of the present invention, becomes poor.

Further, the polyester film of the present invention is
It is preferable to contain 1 to 20% by weight of modified PBT,
More preferably 3 to 18% by weight, particularly preferably 5 to 1
It is 5% by weight. Within such a preferable range, the pinhole resistance, particularly the flex resistance, which is the object of the present invention, is excellent, while the mechanical strength does not decrease.

Examples of the polymerization catalyst for producing the polyester used in the present invention include alkali metal compounds, alkaline earth metal compounds, zinc compounds, lead compounds, manganese compounds, cobalt compounds, aluminum compounds, antimony compounds and titanium compounds. Etc., and a germanium compound, an antimony compound and a titanium compound are preferably used. Further, a coloring preventing agent may be used,
For example, a phosphorus compound or the like can be used.

The polymerization catalyst and the anti-coloring agent are usually preferably added at an arbitrary stage before the completion of the polyester polymerization. As such a method, for example,
Taking a germanium compound as an example, a method of adding a germanium compound powder as it is, or Japanese Patent Publication No.
As described in Japanese Patent No. 22234, there may be mentioned a method of dissolving and adding a germanium compound in a glycol component which is a starting material of polyester.
Examples of the germanium compound include germanium dioxide, germanium hydroxide containing water of crystallization, or germanium tetramethoxide, germanium tetraethoxide, germanium tetrabutoxide, germanium alkoxide compounds such as germanium ethylene glycoloxide, germanium phenolate, germanium β- A germanium phenoxide compound such as naphtholate, a phosphorus-containing germanium compound such as germanium phosphate and germanium phosphite, and germanium acetate can be used. Of these, germanium dioxide is preferable. Also,
As the antimony compound, for example, antimony oxide such as antimony trioxide, antimony acetate or the like can be used. As the titanium compound, alkyl titanate compounds such as tetraethyl titanate and tetrabutyl titanate are preferably used.

The polyester subjected to polycondensation reaction at high temperature and reduced pressure is further subjected to solid-state polymerization reaction at a temperature below its melting point under reduced pressure or in an inert gas atmosphere to reduce the content of acetaldehyde, Intrinsic viscosity and amount of carboxyl end groups can be adjusted.

The polyester film of the present invention has an intrinsic viscosity of 0.5 in terms of impact resistance, heat resistance, productivity and low elution property.
˜1 dl / g is preferred, particularly preferably 0.55
It is 0.7 dl / g.

In the polyester film of the present invention, in order to achieve both handleability, processability and surface haze, internal particles having an average particle size of 0.01 to 5 μm, and external particles such as inorganic particles and / or organic particles are used. It is preferable that the content of particles arbitrarily selected from 0.01 to 10% by weight is contained, and particularly 0.01 to 0.2% by weight is contained.

Here, as a method of depositing the internal particles, for example, JP-A-48-61556 and JP-A-51-12 are available.
Techniques described in JP-A-860, JP-A-53-41355, JP-A-54-90397 and the like can be mentioned. Further, JP-A-55-20496 and JP-A-59.
It can also be used in combination with other particles described in JP-A-204617. In addition, it is not preferable to use particles having an average particle size of more than 10 μm because defects such as film breakage easily occur.

Examples of the inorganic particles and / or organic particles include wet and dry silica, colloidal silica, aluminum silicate, titanium oxide, calcium carbonate,
Calcium phosphate, barium sulfate, alumina, mica,
Examples thereof include inorganic particles such as kaolin and clay, and organic particles including styrene, silicone, acrylic acid and the like as constituent components.

Two or more kinds of these internal particles, inorganic particles and / or organic particles may be used in combination. From the viewpoint of controlling the surface haze, spherical particles are preferable, and silica and alumina are particularly preferable.

In the biaxially oriented polyester film of the present invention, additives such as an antistatic agent, a heat stabilizer, an antioxidant, a crystal nucleating agent, a weathering agent, an ultraviolet absorber, a pigment and a dye are used for the purpose of the present invention. It can be used in a range that does not impair it.
The method of adding these additive components is not particularly limited, and they can be added, for example, during melt polymerization of polyester, during solid phase polymerization, or in an extruder.

The biaxially oriented polyester film of the present invention has (1) a loss elastic modulus (E ") of 2 at the peak temperature of β dispersion.
00 MPa or more, preferably 300 MPa or more, more preferably 400 MPa or more, particularly preferably 500 MP
or (1) ′ The deformation recovery rate after 20% tension at 0 ° C. is 55% or more, preferably 58% or more, more preferably 60% or more. Loss elastic modulus (E ") at peak temperature of β dispersion is 200 MPa
If it is less than 50% or the deformation recovery rate after 20% tension at 0 ° C. is less than 55%, the pinhole resistance becomes poor.

As a method of setting the loss elastic modulus (E ") at the peak temperature of β dispersion to 200 MPa or more, for example, a melting point of 240 to 265 ° C. and 90% by weight or more of ethylene terephthalate and / or ethylene naphthalate are used. Resin (A) consisting of polyester component
5 to 95% by weight, and melting point of 185 to 235 ° C. is 70
Resin (B) containing 5% or more by weight of polyester component
It is effective to use a blended polymer prepared by mixing and mixing 45 to 45% by weight. Further, it is preferable not only to use the resin as described above but also to carry out a treatment for enhancing the mobility of the amorphous portion of the resin by applying a specific energy after the biaxial stretching. As a method of applying such energy, infrared rays, an additive that absorbs electromagnetic waves of specific wavelengths such as ultraviolet rays is added in advance, a method of irradiating an electromagnetic wave, a method of irradiating an electron beam, a method of heating under specific conditions, A combination of these and the like can be adopted. Above all, the resin (A) having the above melting point,
It is effective to use (B) as a mixture and to perform heat treatment in the vicinity of the melting point of the resin (B).

The deformation recovery rate after 20% tension is 55%.
As a method of making the above, for example, kneading an elastomer such as modified PBT is effective. Since the elastomer is a rubber elastic body and returns to its original shape when the external force is removed after being deformed by applying an external force, if it is dispersed in the film, the deformation recovery rate after 20% tension is increased. Because you can.

Further, the peak temperature of β dispersion and the temperature at half the loss elastic modulus (E ") at the peak temperature (high temperature side)
The absolute value of the difference from is preferably 30 ° C. or higher, more preferably 35 ° C. or higher, and particularly preferably 40 ° C. or higher.

The β-dispersion is considered to be stress relaxation due to the segment in the molecular chain, and it is considered that the larger the relaxation strength of the β-dispersion (peak area of β-dispersion), the more stress relaxation is possible. That is, the loss elastic modulus (E ") is large, and
The broader the β-dispersion peak is, the higher the relaxation strength is, and it is considered that this is largely related to the relaxation of the impact from the outside or the impact due to bending.

In order to increase the β-dispersion peak area, that is, to increase the β-dispersion strength, not only the above resin (A) and resin (B) are kneaded within a prescribed range, but also the amorphous portion undergoes a conformational change. It is preferable to carry out a treatment that makes it easier to remove. For example, when the film is produced by a sequential biaxial stretching method in which the film is stretched in the longitudinal direction and then stretched in the width direction, preheating before stretching is performed in both the longitudinal direction and the width direction.
The preheating temperature is preferably higher than usual in order not to suppress the amorphous conformational change. The preferred preheating temperature is the glass transition temperature of the resin (A) +20 to +8
0 ° C., more preferably glass transition temperature +25 to +75
C., particularly preferably +25 to +65. The preheating time is preferably 2 to 60 seconds, more preferably 3 to 30 seconds.
Seconds. When preheating is carried out at a temperature below this range, the molecular chains are stretched in a state where the mobility is low, and therefore the molecular chains are stretched, resulting in a structure in which it is difficult to change the conformation, resulting in a β dispersion strength. If it is carried out at a temperature above this range, the film will stick to the roll and the surface of the film will become rough.

It is also an effective means to reduce the crystal size. Even if the crystallinity is the same, the number of crystals is larger when the crystal size is smaller than when the crystal size is large, that is, the ratio of the amorphous material constrained between the crystals increases. This amorphous portion has less entanglement and a larger free volume than the random coil-shaped amorphous portion, and has a structure in which a conformation change can be easily taken, and therefore β dispersion strength becomes large. Although the method for reducing the crystal size is not limited to this, for example, when the heat treatment after stretching is performed at a high temperature for 5 seconds or less, the crystallinity increases but the crystal size grows. There is not enough time, and as a result, a small crystal size is formed, or an appropriate amount of a crystal nucleating agent is contained, and the heat treatment temperature is 100 to 180 ° C., preferably 120 to 160 ° C. If a film with the desired crystallinity and density is obtained, it is possible to form a film with a smaller crystal size than the one with the same crystallinity and density produced without the inclusion of a crystal nucleating agent, and a film with a large β dispersion strength can be obtained. To be

The breaking strength of the biaxially oriented polyester film of the present invention must be 140 MPa or more,
Preferably 160 MPa or more, particularly preferably 180 M
Pa or higher. When it is less than 140 MPa, for example, when it is used as a packaging material, if the content contains sharp particles such as rice grains or fish bones, pinholes are easily formed,
The contents are likely to be damaged or leaked.

The Young's modulus of the biaxially oriented polyester film of the present invention is preferably 2.5 to 4.0 GPa, more preferably 2.7 to 3.8 GPa, and particularly preferably 2.9 to 3.7 GPa. is there. When it exceeds 4.0 GPa, the flexibility is poor and pinholes are easily formed, and when it is less than 2.5 GPa, slack tends to occur during molding.

Next, the biaxially oriented polyester film of the present invention preferably has a total elongation at break of 250% or more in the longitudinal and width directions from the viewpoint of moldability.
It is more preferably 280 to 700%, and particularly preferably 300 to 700%. If it is less than 250%, the moldability is lowered, which is not preferable, and if it exceeds 700%, the workability is lowered, which is not preferable.

A surface orientation coefficient of 0.10 to 0.17 is preferable from the viewpoint of excellent impact resistance, moldability, prevention of whitening during bending and prevention of loosening during high temperature molding. It is preferably 0.10 to 0.16, particularly preferably 0.10 to 0.15. Further, from the viewpoint of imparting followability in each direction and uniform moldability, it is desirable that the variation of the plane orientation coefficient is small, and the plane orientation coefficient when 10 points are measured at 3 cm intervals in the longitudinal direction or the width direction of the film. The difference between the maximum and the minimum is preferably 0.02 or less, more preferably 0.01 or less, and particularly preferably 0.005 or less.

The method for controlling the plane orientation coefficient of the film within the above range is not particularly limited, but for example, the stretching ratio in the longitudinal direction or the width direction of the film, the stretching temperature, the stretching speed, and the heat treatment. This can be achieved by adjusting the temperature or the heat treatment time.

The biaxially oriented polyester film of the present invention preferably has a heat shrinkage rate of -1 to 5% at 150 ° C for 30 minutes from the viewpoint of suppressing thermal dimensional change during processing and appropriate self-tension load. , And more preferably 0 to 4%. It is particularly preferably 0 to 3%.

The biaxially oriented polyester film of the present invention preferably has an acetaldehyde content of 30 ppm or less, more preferably 25 ppm or less, and particularly preferably 20 p, from the viewpoint of improving hygiene.
It is pm or less. The method for adjusting the acetaldehyde content in the film to 30 ppm or less is not particularly limited. For example, a method of solid-phase polymerizing polyester at a temperature of 150 ° C. or more and a melting point or less under a reduced pressure or an inert gas atmosphere, a vacuum vent type extruder Can be carried out by a method such as melt extrusion.

The production method of the biaxially oriented polyester film of the present invention will be described, but the production method is not particularly limited thereto. After drying the polyester as required, it is supplied to a known melt extruder, extruded into a sheet form from a slit die, and cooled and solidified by closely adhering to a casting drum by a method such as electrostatic application to obtain an unstretched sheet. .

The unstretched sheet is stretched and heat-treated in the longitudinal direction and width direction of the film to obtain the desired film.
From the viewpoint of the quality of the film, a tenter method is preferable, and a sequential biaxial stretching method in which the film is stretched in the longitudinal direction and then stretched in the width direction, and a simultaneous biaxial stretching method in which the longitudinal direction and the width direction are stretched almost simultaneously. preferable.

The stretching ratio is 1.
5-4.0 times is preferable, More preferably, it is 1.8-4.
It is 0 times. Either the stretching ratio in the longitudinal direction or the stretching ratio in the width direction may be increased or may be the same. The stretching speed is preferably 1000% / min to 200,000% / min. The stretching temperature is preferably 80 to 150 ° C.

The film is heat-treated after the biaxial stretching, but this heat-treatment method is not particularly limited, and a known method such as in an oven or on a heated roll can be used. In the heat treatment, the film temperature is the melting point of the resin (B) -60.
To −5 ° C. is preferable, more preferably −55 to −7 ° C.,
Particularly preferably, it is -50 to -10 ° C. If the heat treatment is less than the melting point of the resin (B) −60 ° C., the thermal dimensional stability becomes poor, and if the temperature exceeds the melting point of the resin (B) −5 ° C., the crystallization proceeds with the resin (A). The difference in physical properties becomes large,
The stress is not evenly applied during bending, resulting in poor pinhole resistance.

The heat treatment may be performed while relaxing the film in the longitudinal direction and / or the width direction thereof. Further, the re-stretching may be performed once or more in each direction, and the heat treatment may be performed after the re-stretching.

The thickness of the biaxially stretched film of the present invention can be set to any thickness, but it is preferably 3 to 100 μm, more preferably 10 to 80 μm, and particularly preferably 10 to 50 μm. If it is less than 3 μm, the mechanical strength will be poor, and if it exceeds 100 μm, the flexibility will be poor.

The biaxially oriented polyester film of the present invention may be used as a single layer or as a laminate. When laminated and used, polymers such as thermoplastic polymers and thermosetting polymers may be laminated. The laminated structure is not particularly limited, and the biaxially oriented polyester film of the present invention is laminated on one surface to be two layers, the center is laminated to three layers, two or more kinds of films are laminated, or four or more films are laminated. Is also good.

Biaxially oriented polyester film of the present invention
Is a surface treatment such as corona discharge treatment.
With, the adhesiveness can be improved. The process at that time
5 ~ 50W ・ min / m as physical strength²Is preferred, and more
Preferably 10 to 45 W · min / m ²Is. In addition,
There are surface irregularities such as boss processing and sand mat processing.
Corona discharge treatment, plasma treatment, alkali treatment, etc.
You may perform the surface treatment of this as needed.

Further, the biaxially oriented polyester film of the present invention is provided with an easy-adhesion treatment agent, an antistatic agent, a water vapor / gas barrier agent (such as polyvinylidene chloride), a release agent, an adhesive,
Adhesives, flame retardants, UV absorbers, matting agents, pigments, dyes, etc. may be coated or printed, and metals such as aluminum, aluminum oxide, silicon oxide, and palladium and their compounds are shielded from light, water vapor and gas barriers, It may be vacuum-deposited for the purpose of surface conductivity, infrared reflection, etc.,
The purpose and method are not limited to these.

The use of the biaxially oriented polyester film of the present invention is not particularly limited, but it is preferably used for packaging materials and molding.

The methods for measuring and evaluating the various physical properties and characteristics used in the present invention will be described below. (1) Melting point (Tm), sub-endothermic peak due to heat treatment (Tmeta) It was measured using a differential scanning calorimeter (DSC2 manufactured by Perkin-Elmer). Resin sample 10mg under nitrogen stream 1
The melting point (Tm) was defined as the endothermic peak temperature associated with crystal melting during the process of heating from 20 ° C to 280 ° C at a rate of 0 ° C / min. In addition, 10 mg of the film sample was subjected to 1 in a nitrogen stream.
The sub-endothermic peak due to the heat treatment in the process of raising the temperature from 20 ° C to 280 ° C at a rate of 0 ° C / min was defined as Tmeta. (2) Deformation recovery rate The width of the film sample is 10 mm, the test length is 150 mm, the distance between the marked lines is 100 mm, and 20% pulling is performed at 0 ° C. and 65% RH using an Instron type tensile tester and kept for 30 seconds After releasing the tension, measure the length between the marked lines,
The deformation recovery rate was calculated by the following formula.

Deformation recovery rate = {1- (between deformed gauge lines-10)
0) / 20} × 100 (3) β dispersion peak temperature, loss elastic modulus (E ") Dynamic viscoelastic device (" RHEOVIB "manufactured by ORIENTEC)
RON "DDV-II-EA) measuring frequency 11
0MHz, vibration displacement 16μm (single amplitude), initial load 5g,
Measurement temperature range -130 ° C to 240 ° C, temperature rising rate 2 ° C /
Min., Loss elastic modulus (E ") was obtained at a sample size of 40 mm x 4 mm (longitudinal direction x width direction), and the peak temperature due to β dispersion observed at 0 ° C or lower at this time, the loss elasticity at the peak temperature The rate (E ") was determined. (4) Breaking strength Regarding breaking strength, according to the method specified in JIS K 7127, using an Instron type,
The stress when the film broke when measured at 65% RH was measured. (5) Elastic Modulus The elastic modulus was measured at 25 ° C. and 65% RH using an Instron type tensile tester according to the method specified in JIS Z 1702. (6) Elongation Regarding elongation, using an Instron type tensile tester according to the method specified in JIS K 7127,
The elongation at break was defined as (extended length / original sample length) × 100 when measured at 25 ° C. and 65% RH. (7) Plane Orientation Coefficient (fn) The refractive index (Nx, Ny, N in the longitudinal direction, the width direction, and the thickness direction is measured using an Abbe refractometer with sodium D line as a light source.
z) was measured and determined by the following formula.

Fn = (Nx + Ny) / 2-Nz (8) Heat Shrinkage Ratio of the film sample in the longitudinal direction (MD) and the width direction (T).
The distance between the marked lines in D) is set to 200 mm and the film is set to 10 mm.
Cut to width and hang the film sample in the length direction, 1
Apply a load of g in the lengthwise direction and use hot air at 190 ° C 3
After heating for 0 minutes, the length between marked lines was measured, and the shrinkage amount of the film was expressed as a percentage as a ratio to the original size. (9) The intrinsic viscosity film was dissolved in orthochlorophenol and measured at 25 ° C. (10) Pinhole resistance-1 Using a gel bot tester specified in ASTM F-392, a film sample (280 mm x 180 mm) was subjected to a gel bolus repeated bending test 500 times at an ambient temperature of 0 ° C. The number of pinholes after the test was measured.
Grade C and above are acceptable.

Class A: 2.5 or less pinholes Class B: 5.5 or less pinholes Class C: 9 or less pinholes Class D: More than 9 pinholes or break. (11) Pinhole resistance-2 A film with a diameter of 40 mm is stretched without sagging, a sapphire needle with a tip angle of 60 degrees and a tip R of 0.5 mm is used, and the center of the circle is at a speed of 50 mm / min. The load at the time of piercing and penetrating the needle was converted to 1 mm of the film and defined as the piercing strength. Grade B and above are acceptable.

Class A: Strength is 25 kg / mm or more B class: Strength is 20 kg / mm or more C class: Strength is less than 20 kg / mm (12) Moldability Tip is hemispherical (radius 3 cm), body is cylindrical (Radius 3
(cm) is heated to 185 ° C. and then pushed into a film that is firmly attached to a 20 cm square metal frame, and the drawing ratio is 0.8.
Molding was carried out and evaluated as follows. Grade B and above are acceptable. Grade A: Uniformly molded, and the molded body has no slack.

Class B: There is a part with uneven thickness, but the whole is molded uniformly and there is no slack after molding.

Class C: Apparently uneven molding, and surface roughness is recognized.

[0060]

The present invention will be described below with reference to examples. (Example 1) 80% by weight of polyethylene terephthalate as polyester (A), 18% by weight of polybutylene terephthalate as polyester (B), melting point 160
2% by weight of modified PBT at ℃, average particle size 0.2μm
Was adjusted to contain 0.05% by weight of alumina particles. The polymer chips were vacuum dried at 120 ° C. for 6 hours, supplied to a single-screw extruder, discharged from a normal die, and then solidified by cooling with a mirror cooling drum while applying static electricity to obtain an unstretched film. This unstretched film was stretched 3.2 times in the longitudinal direction at a stretching temperature of 88 ° C. with a non-adhesive silicone roll (hardness 73 °), and then in a tenter at 110 ° C. in the widthwise direction.
The film was stretched 4 times and then heat-treated at a film temperature of 185 ° C. for 5 seconds to relax 4% in the width direction to obtain a biaxially stretched polyester film having a thickness of 12 μm. The obtained film showed excellent properties as shown in Table 1.

[0061]

[Table 1] The abbreviations in the above table are as follows: PET: polyethylene terephthalate PPT: polypropylene terephthalate PBT: polybutylene terephthalate PET / I: isophthalic acid copolymerized polyethylene terephthalate PBT / DA: dimer acid copolymerized polybutylene terephthalate PBT / I : Isophthalic acid copolymerized polybutylene terephthalate Tm: Melting point Tmeta: Sub-endothermic peak temperature F _MD caused by heat treatment F _MD : Longitudinal breaking elongation F _TD : Width breaking elongation (Example 2) Polyethylene as polyester (A) 80% by weight of terephthalate, 15% by weight of polybutylene terephthalate copolymerized with 10 mol of isophthalic acid as polyester (B), and 5% by weight of modified PBT having a melting point of 221 ° C. were used, and 0.01% of spherical silica particles having an average particle size of 1.2 μm was used.
It was adjusted to contain 2% by weight. 12 polymer chips
After vacuum drying at 0 ° C. for 6 hours, it was supplied to a single-screw extruder, discharged from an ordinary die, and then cooled and solidified by a mirror surface cooling drum while applying static electricity to obtain an unstretched film. This unstretched film was stretched 3.0 times in the longitudinal direction at a stretching temperature of 85 ° C. with a non-adhesive silicone roll (hardness 73 °), and then stretched 3.0 times in the width direction at 120 ° C. in a tenter, and then, The film was biaxially stretched to a thickness of 15 by relaxing it by 4% in the width direction while heat-treating the film at 190 ° C for 5 seconds.
A μm polyester film was obtained. The obtained film showed excellent properties as also shown in Table 1. (Example 3) 85% by weight of polyethylene terephthalate as polyester (A), 5% by weight of polybutylene terephthalate as polyester (B), melting point 219 ° C
The modified PBT of 10% by weight is used, and the average particle size is 1.5 μm.
It was adjusted to contain 0.03% by weight of the agglomerated silica particles. The polymer chips were vacuum dried at 120 ° C. for 6 hours, supplied to a single-screw extruder, discharged from a normal die, and then solidified by cooling with a mirror cooling drum while applying static electricity to obtain an unstretched film. This unstretched film was stretched 3.8 times in the longitudinal direction at a stretching temperature of 85 ° C. with a non-adhesive silicone roll (hardness 80 °), and then in a tenter at 110 ° C. in the widthwise direction.
The film was stretched 8 times and then heat-treated at a film temperature of 205 ° C. for 8 seconds to relax 4% in the width direction to obtain a biaxially stretched polyester film having a thickness of 20 μm. The obtained film is as shown in Table 1 together.
It showed excellent properties. (Example 4) Using 80% by weight of polyethylene terephthalate as the polyester (A) and 20% by weight of polypropylene terephthalate as the polyester (B), it was adjusted to contain 0.05% by weight of alumina particles having an average particle diameter of 0.2 μm. did. The polymer chips were vacuum dried at 150 ° C. for 3 hours, fed to a single-screw extruder, discharged from an ordinary die, and then cooled and solidified by a mirror cooling drum while applying static electricity to obtain an unstretched film. This unstretched film is stretched with a non-adhesive silicone roll (hardness 73 °) at a stretching temperature of 90 ° C.
After stretching 3.0 times in the longitudinal direction at 120 ° C in the tenter
At a film temperature of 20.
Relaxing 4% in width while heat treating at 2 ℃ for 5 seconds
By doing so, a biaxially stretched polyester film having a thickness of 15 μm was obtained. The obtained film showed excellent properties as also shown in Table 1. (Example 5) Polyethylene terephthalate (70% by weight) is used as polyester (A), polybutylene terephthalate (30% by weight) is used as polyester (B), and 0.012% by weight of spherical silica particles having an average particle diameter of 0.8 μm is contained. Was adjusted. The polymer chips were vacuum dried at 150 ° C. for 3 hours, fed to a single-screw extruder, discharged from an ordinary die, and then cooled and solidified by a mirror cooling drum while applying static electricity to obtain an unstretched film. This unstretched film was stretched with a non-adhesive silicone roll (hardness 80 °) at a stretching temperature of 95.
After stretching 2.9 times in the longitudinal direction at ℃, 115 in the tenter
Stretched 2.9 times in the width direction at ℃, then film temperature 1
Relax in the width direction while heat-treating at 85 ° C for 5 seconds 3
%, A biaxially stretched polyester film having a thickness of 10 μm was obtained. The obtained film showed excellent properties as also shown in Table 1. (Example 6) Isophthalic acid 6 as polyester (A)
60% by weight of molar copolymerized polyethylene terephthalate,
As the polyester (B), 40% by weight of 17 mol of dimer acid copolymerized polybutylene terephthalate was used, and 0.012% by weight of spherical silica particles having an average particle size of 1.2 μm was contained. The polymer chips were vacuum dried at 150 ° C. for 3 hours, fed to a single-screw extruder, discharged from an ordinary die, and then cooled and solidified by a mirror cooling drum while applying static electricity to obtain an unstretched film. This unstretched film is stretched with a non-adhesive silicone roll (hardness 73 °) at a stretching temperature of 85 ° C.
After stretching 2.7 times in the longitudinal direction at 120 ° C in a tenter
At a film temperature of 17
Relaxing 4% in the width direction while heat treating at 8 ° C for 5 seconds
By doing so, a biaxially stretched polyester film having a thickness of 25 μm was obtained. The obtained film showed excellent properties as also shown in Table 1. (Example 7) Polyethylene terephthalate was used as the polyester (A) in an amount of 80% by weight, isophthalic acid 10 mol copolymerized polybutylene terephthalate was used in an amount of 20% by weight as the polyester (B), and the agglomerated silica particles having an average particle diameter of 1.5 μm were 0%. It was adjusted to contain 0.03% by weight. The polymer chips were vacuum dried at 150 ° C. for 3 hours, fed to a single-screw extruder, discharged from an ordinary die, and then cooled and solidified by a mirror cooling drum while applying static electricity to obtain an unstretched film. This unstretched film was stretched 3.8 times in the longitudinal direction at a stretching temperature of 82 ° C. with a non-adhesive silicone roll (hardness 80 °), and then stretched 3.8 times in the width direction at 110 ° C. in a tenter. A biaxially stretched polyester film having a thickness of 30 μm was obtained by relaxing the film in a width direction by 4% while heat-treating at a film temperature of 172 ° C. for 5 seconds.
The obtained film showed excellent properties as also shown in Table 1. Comparative Example 1 100% by weight of polyethylene terephthalate was used as polyester, and 0.03% by weight of agglomerated silica particles having an average particle diameter of 1.5 μm was contained.
The polymer chips were vacuum dried at 150 ° C. for 3 hours, fed to a single-screw extruder, discharged from an ordinary die, and then cooled and solidified by a mirror cooling drum while applying static electricity to obtain an unstretched film. This unstretched film was stretched 3.0 times in the longitudinal direction at a stretching temperature of 100 ° C with a non-adhesive silicone roll (hardness 80 °), and then in a tenter at 120 ° C in the width direction.
The film was stretched 1-fold and then heat-treated at a film temperature of 230 ° C. for 5 seconds to relax 4% in the width direction to obtain a biaxially stretched polyester film having a thickness of 20 μm. As shown in Table 2, the obtained film was inferior in pinhole resistance-1 (gelvo test) in this example in which the weight parts of the resins (A) and (B) were out of the range of the present invention.

[0062]

[Table 2] The abbreviations in the above table are as follows: PET: polyethylene terephthalate PBT: polybutylene terephthalate PBT / I: isophthalic acid copolymerized polybutylene terephthalate Tm: melting point Tmeta: sub-heat absorption peak temperature F _MD due to heat treatment: longitudinal Breaking elongation in the direction F _TD : breaking elongation in the width direction (Comparative Example 2) 40% by weight of polyethylene terephthalate as the polyester (A) and 60% by weight of 10 mol of isophthalic acid copolymerized polybutylene terephthalate as the polyester (B) Was adjusted to contain 0.012% by weight of spherical silica particles having an average particle size of 1.2 μm. The polymer chips were vacuum dried at 150 ° C. for 3 hours, fed to a single-screw extruder, discharged from an ordinary die, and then cooled and solidified by a mirror cooling drum while applying static electricity to obtain an unstretched film. This unstretched film was stretched in the longitudinal direction at a stretching temperature of 70 ° C. with a non-adhesive silicone roll (hardness 73 °).
After being stretched 8 times, it is stretched 2.0 times in the width direction at 110 ° C. in a tenter, and then heat-treated at a film temperature of 180 ° C. for 5 seconds to relax 4% in the width direction to obtain 2%.
An axially stretched polyester film having a thickness of 30 μm was obtained. As shown in Table 2 together with the obtained film, the parts in which the parts by weight of the resins (A) and (B), the breaking strength, the Young's modulus, and the plane orientation coefficient are out of the range of the present invention, the pinhole resistance- 2 (piercing strength), inferior in moldability. (Comparative Example 3) 95% by weight of polyethylene terephthalate is used as the polyester (A), 5% by weight of polybutylene terephthalate is used as the polyester (B), and 0.03% by weight of agglomerated silica particles having an average particle diameter of 1.5 μm is contained. Was adjusted. The polymer chips were vacuum dried at 150 ° C. for 3 hours, fed to a single-screw extruder, discharged from an ordinary die, and then cooled and solidified by a mirror cooling drum while applying static electricity to obtain an unstretched film. This unstretched film was stretched 4.2 times in the longitudinal direction at a stretching temperature of 85 ° C. by a non-adhesive silicone roll (hardness 73 °), and then stretched 4.3 times in the width direction at 110 ° C. in a tenter, and then, Film temperature 220
A biaxially stretched polyester film having a thickness of 80 μm was obtained by heat-treating at 5 ° C. for 5 seconds and relaxing 4% in the width direction. As shown in Table 2 together with the obtained film, loss modulus of β dispersion, absolute value of difference between peak temperature of β dispersion and half-value temperature of loss modulus, Young's modulus, elongation at break, heat shrinkage at 150 ° C. In this example, the ratio and the surface orientation coefficient were out of the range of the present invention, the pinhole resistance-1 (gelvotest) and the moldability were poor.

[0063]

According to the present invention, there is provided a biaxially oriented polyester film for molding, which has an elongation which is not found in conventional PET films and which is excellent in processing characteristics such as heat resistance, dimensional stability and moldability. You can

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4F071 AA45 AA46 AA47 AA78 AA83                       AA84 AF14 AF20 AF61 AH04                       AH14 BA01 BB06 BB08 BC01                       BC17                 4J002 CF052 CF061 CF072 CF103                       FD200 GG02 GS01

Claims (8)

[Claims] 1. A biaxially oriented polyester film, wherein the resin components are the following (A) and (B) and have the following properties (1) and (2). (A) Resin content 5 consisting of a polyester component having a melting point of 240 to 265 ° C. and 90% by weight or more of ethylene terephthalate and / or ethylene naphthalate
5 to 95% by weight (B) Resin content of which melting point is 185 to 235 ° C. and 70% by weight or more is polyester component 5 to 45% by weight (1) Loss elastic modulus (E ") at peak temperature of β dispersion Two
00 MPa or more (2) Breaking strength of the film is 140 MPa or more 2. A biaxially oriented polyester film, wherein the resin components are the following (A) and (B) and have the following properties (1) ′ and (2). (A) Resin content 5 consisting of a polyester component having a melting point of 240 to 265 ° C. and 90% by weight or more of ethylene terephthalate and / or ethylene naphthalate
5 to 95% by weight (B) Melting point of 185 to 235 ° C. and resin content of 70% by weight or more consisting of polyester component 5 to 45% by weight (1) ′ Deformation recovery rate after 20% tension of film at 0 ° C. 55% or more (2) Breaking strength of the film is 140 MPa or more 3. The modified polybutylene terephthalate having a melting point of 140 to 230 ° C. and a polyether unit of 20 to 85% by weight, which is incorporated in an amount of 1 to 20% by weight, according to claim 1 or 2. Biaxially oriented polyester film. 4. The absolute value of the difference between the peak temperature of β dispersion and the temperature (high temperature side) which is half the loss elastic modulus (E ″) at the peak temperature is 30 ° C. or more. The biaxially oriented polyester film according to claim 1 or 3. 5. The Young's modulus of the film is 2.5 to 4.0 G.
It is Pa, The biaxially oriented polyester film in any one of Claims 1-4. 6. The total elongation at break of the film in the longitudinal and width directions is 250% or more.
The biaxially oriented polyester film according to any one of to 5. 7. The plane orientation coefficient of the film is from 0.10 to 0.
17. The biaxially oriented polyester film according to claim 1, wherein the biaxially oriented polyester film is 17. 8. The biaxially oriented polyester film according to claim 1, wherein the film has a heat shrinkage ratio of 5% or less at 150 ° C. for 30 minutes.