JPS62135536A - Biaxially oriented copolyester film - Google Patents

Abstract

PURPOSE:To provide the titled film having excellent gas barrier properties and impact resistance, by molding a copolyester having specified structural units into a film. CONSTITUTION:A dicarboxyl acid consisting of 1,2-bis(2-chlorophenoxy) ethane-4,4'-dicarboxylic acid (ester) and isophthalic acid (ester) is polycondensed with ethylene glycol and a dicarboxylic acid (ester) of formula I and/or an oxycarboxylic acid (ester) of formula II to obtain a copolyester composed of structural units of formulas III, IV, V and/or VI in such a molar ratio as to satisfy the relationships of formulas VII and VIII. The polyester is extruded into a film, which is then biaxially oriented to obtain a biaxially oriented copolyester film having a melt viscosity of 500-20,000P and Young's modulus of 900kg/mm<2> or above in the sum of lengthwise and widthwise directions.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a polyester film, and more particularly to a polyester film with excellent gas barrier properties.

[Prior art] Polyester films include polyethylene α, β-
Bis(2-chlorophenoxy)ecun 4, /1'
- A film consisting of dicarboxylate is dried for one day. (For example, Japanese Unexamined Patent Publication No. 59-38031) [Problems that the invention attempts to solve] However, the above-mentioned polystyrene film still does not have sufficient gas barrier properties, and, for example, when it is made into a bag, the film It had the disadvantage of poor impact resistance.

An object of the present invention is to eliminate the above-mentioned drawbacks and to provide a polyester film that has good gas barrier properties and excellent impact resistance.

[Means for Solving Problem 1] In order to achieve the above object, the present invention has the following structure, that is, the following structure units (I) and (II) are combined with the following groove) noble unit (1), A film mainly composed of a copolyester containing at least one of (1v) and having a molar ratio of the structural units satisfying the following formulas (A) and (B),
In addition, the film has a sum of Young's moduli in the longitudinal direction and width direction of 900 kg/mm2 or more, and a melt viscosity of 500 to 2000.
This is a biaxially oriented polyester film with zero voids.

・・・・・・・・・(1) ・・・・・・・・・(II) ・・・・・・・・・(I) 0.001≦[(III) 10(IV) ]/ (I)
≦0, 2 ・・・・・・・・・
...(△)0.2≦(II>/[(1)+(II)+
(III)+(IV)]≦0.7...
......(B) The polyester constituting the present invention is
The above structural units (I) and (It) have the above structure (1),
It is a polyester containing at least one of (IV). However, other components may be copolymerized as long as they do not interfere with the present invention, preferably less than 5 mol %. In this case, the copolymerization components include terephthalic acid, naphthalene dicarboxylic acid, 4.4°-binoenyl dicarboxylic acid, α,β-bis(phenoxy)ethane 4,
4-dicarboxylic acid, α(2-chlorophenoxy)-B(
Phenoxy〉ethane 4,4-dicarboxylic acid or 1
．． It is a dioxy compound such as 4-cyclohexane dimetatool.

Regarding the structural units constituting the polyester of the present invention, the molar ratio ([(III)+(Iv)]/(I)) is R, and R is 0.001 to 0. 2. If R is smaller than this range, the 1tli impact resistance of the film will be poor, and conversely, if R is larger than this range, the gas barrier property will be poor, which is not preferable. The structural unit has the molar ratio ((n)/[(1)+ (II)+ (l[[)
+ (IV) ]) is S, S must be 0.2~O,,7-(-) as in equation (B), but this St is 10.4~0.7. is preferable, and 0.5 to
More preferably, it is 0.6.

In addition, other types of polymers may be blended into the polyester of the present invention within a range that does not impede the object of the present invention, preferably within 10% by weight, and antioxidants,
Inorganic or line specific additives such as heat stabilizers, ultraviolet absorbers, surface protrusion forming agents, nucleating agents, etc. may be added to commonly used minimum levels.

The present invention is a biaxially oriented and reinforced film of the copolymerized polyester described above, which has a sum of Young's moduli in the longitudinal direction and the width direction of 900 ki/mm2, preferably 1000 ki/mm2.
It is necessary that it is at least g/mm2. If the sum of Young's moduli is smaller than the above range, impact resistance and gas barrier properties will be poor, which is not preferable. Note that the upper limit of the sum of Young's moduli is not particularly limited, but it is necessarily about 2500 kg/mm 2 as a manufacturing limit.

Temperature of the film of the present invention: 290'C1 Shear rate: 200se
It is necessary that the melt viscosity of the c-i-te is 500 to 20,000 voids, preferably 1,000 to 10,000 voids. If the melt viscosity is smaller than the above range, the gas barrier properties and impact resistance will be poor, whereas if the melt viscosity is larger than the above range, the gas barrier properties will be poor, which is not preferable.

Further, the density index of the film of the present invention is not particularly limited, or is 0.01 to 0.09, preferably 0°02 to 0.08.
When it is in the range of -M, the film has better gas barrier properties and impact resistance, so it is desirable.

Further, the difference in refractive index between the longitudinal direction and the width direction (longitudinal direction - width direction) of the film of the present invention is not particularly limited, but is -0,1
A value in the range of 0-0.10 is desirable because the impact resistance of the film becomes even better.

Next, the method for producing the film of the present invention will be explained.

First, the polyester of the present invention is used as the main cylinder 1.
2-bis(2-chlorophenoxy)ethane-4,4゛-
A dicarboxylic acid component consisting of dicarboxylic acid or its ester and isophthalic acid or its ester, and a diol component mainly consisting of ethylene glycol are used.

Generally, dicarboxylic acid or its ester and/or oxycarboxylic acid or its ester shown below are used together with the main raw materials.

As the polycondensation method, a method of directly polycondensing a predetermined carboxylic acid and ethylene glycol, a method of polycondensing a predetermined carboxylic acid ester and ethylene glycol by a transesterification method, etc. can be used. Here, the melt viscosity of this copolymerized polynisdel is 700 to 21,000.
Adjusting the degree of polymerization so that it falls within the voice range is effective in obtaining the melt viscosity range of the film of the present invention.

Next, this copolyester pellet is dried, clarified,
The product is fed to the extruder (2) on January 11, 2011, and extruded into a sheet through a slit die, cooled and solidified to produce an unstretched film. Next, this unstretched film is biaxially stretched to form a biaxial control surface. As the stretching method, a sequential biaxial stretching method or a simultaneous biaxial stretching method can be used. In the case of the sequential biaxial stretching method, it is common to stretch in the longitudinal direction and then in the width direction, but this order may be reversed. Here, the temperature difference (maximum-minimum) in the width direction of the die should be less than 5°C, and the thickness unevenness in the width direction of the unstretched film should be less than 50%, preferably less than 20%, and more preferably less than 5%. What you can do is
It is effective in effectively stretching the film of the present invention and obtaining a film having a Young's modulus within the range of the present invention. The reason for this is that when the polyester used in the present invention has a large thickness unevenness in the unstretched film, the unstretched film tends to have a poor rolling (Ill 11) quality.
This is not desirable because it becomes difficult to obtain a Young's modulus within the range of the present invention. That is, polyethylene terephthalate, polyethylene-α,β-bis(2-chlorophenoxy)ethane, 4,
Strict thickness control is required compared to 4'-dicarboxylate and the like. In addition, since this polyester is more prone to film stretching breakage due to foreign matter contamination than polyethylene terephthalate, etc., the film is stretched after being filtered using a high-precision filter (for example, Nippon Seiren Co., Ltd.'s NF-03C) during extrusion. This effectively orients the molecules and reduces the Young's modulus to 1n within the range of the present invention (*
It is effective for the first time.

Incidentally, a method of roughly stretching the biaxially stretched film in at least one direction is effective for further improving the gas barrier properties of the film.

Moreover, this stretched film can also be heat-treated if necessary.

In addition, the film of the present invention may be subjected to known corona discharge treatment (in air, nitrogen, carbon dioxide, etc.), and may also be subjected to contact properties, moisture resistance, heat sealability, lubricity, surface smoothness, etc. For the purpose of application, it may be used in the form of a stack of other types of volima or in the form of a coating with other compositions.

In addition, the film of the present invention is used as a magnetic recording material material with a magnetic layer formed on at least one side thereof, and a magnetic layer is formed, which has the characteristic of extremely protecting durability during long-term use. The type of material used is not particularly limited, and known materials such as Fe 203
, Fe30A, CrO2, Fe, Co, Ni, or alloys thereof. Also,
The magnetic layer is made by coating the above-mentioned materials together with an organic binder, or by forming a metal thin film mainly made of the above-mentioned materials by steaming, sputtering, plating, etc. However, in the case of a metal thin film, durability The effect of improving sex is young. The thickness of the magnetic layer is 0.1 to 10 μm for the mold.
For the metal thin film type, the thickness is preferably in the range of 0.03 to 3 μm.

When the film of the present invention is used as a magnetic recording material, the durability improvement effect is exhibited when the average surface roughness of the base film is 0.0005 to 0.05 μm, particularly 0.001 to 0.02 μm. As a method for obtaining the above-mentioned surface roughness, 3!
02, T i 02 etc. inorganic particles of 0.05 to 0.5
Biaxially stretched by the above-mentioned biaxial stretching method at a near-thermal temperature of 140 to 2'IO'C to a
A method of heat treatment for 60 seconds is effective.

[Function] As mentioned above, in the film of the present invention, the special copolymerized polyester is biaxially oriented and has a specific range of Young's modulus and viscosity. ), it is estimated that the following old effects were obtained.

Effect] The film of the present invention has excellent gas barrier properties and is also resistant! 7
This results in a film that has excellent impact resistance and also has excellent sclerosis properties.

Taking advantage of the above characteristics, the film of the present invention can be used for packaging films for foods, medicines, mechanical parts, etc. that are susceptible to deterioration due to oxygen, etc., as well as magnetic tape base films for video or audio, and capacitors that are susceptible to corrosion and performance deterioration due to oxygen or water vapor. Useful for base films.

[Measurement method and evaluation criteria] (1) Young's modulus:
Using an Instron type tensile tester, test at 25°C1.
Measured at 65% RH.

(2) Using a melt viscosity enhancement type flow tester, temperature + x 290'c
The melt viscosity was measured at a sliding speed of 200/sec.

(3) Density was measured at 25°C using a density gradient tube made of isothermal carbon and n-hebutane.

(4) Density index: The density of the biaxially oriented film (rho) was determined by the method described above, and 5! !
j The density (ρ0) of the Qe-directed (amorphous) film was measured, and ρ−ρ0 was defined as the density index.

(5) Oxygen was used as the gas barrier substrate, and the evaluation was made according to the following measurement method and evaluation criteria.

(a> Method for measuring oxygen permeability (PO2) Oxygen permeation A-1 measuring device 0X-TRA manufactured by Modern Control Co., Ltd.
Measurement was performed using N100 model at 20'CO%RH.

(b) Evaluation criteria Oxygen permeability per 15 μm thickness of Noilum is 10 CC/
m2.24 hrs, , atm or less gas barrier property: good,'l Qcc/7p2.24 hrs
, , atm, the gas barrier property was determined to be poor.

(6) Impact resistance (a) Measurement method According to the method specified in ASTM-D-256,
Using a Charpy impact tester made by Toyo Seiki Seisakusho, Charpy street impact strength was measured at 25°C and 165% RH when the film was set horizontally with the hand force direction as the fulcrum and when the film was set horizontally with the width direction as the fulcrum. (Unit: 1 cm
/mm 2 > was measured, and the arithmetic average of both directions was taken as the impact strength.

(b) Evaluation Criteria When the above impact strength was 20 kg·cm/mm 2 or more, the impact resistance was judged to be good, and when it was less than 20 kg·cm/mm 2 , the impact resistance was judged to be poor.

(7) Refractive index Measured at 25° C. and 165% RH using an Atsube refractometer using sodium D line (wavelength 589 nm) as a light source.

Incidentally, a sulfur-medylene iodide solution was used as the mounting solution.

(8) The magnetic recording material of the rA durability sample was slit into a width of 8 mm, and the length was approximately 1 mm.
00m into an 8mm video cassette, 8mmVT
Using R (SONY Corporation MVideo-8), T
V test signal generator (TG-7/1 type manufactured by Shibaku Co., Ltd.)
Record the signal (white signal) from. Next, play this videotape and record the output on a color video noise meter (
925D/1) made by Shibaku Co., Ltd.,
N was measured.

This videotape was played continuously for 720 hours at 40'C, 160% RH, rewound repeatedly, and then
/N was measured. The decrease in 3/N after continuous running is less than 3 dB compared to the S and /N before continuous running. The durability was determined to be poor if the S/N ratio decreased or the S/N decreased by 3 dB or more.

(9) Average surface roughness Measured using a stylus type surface roughness correction according to J15-B-0601. In addition, the cutoff is OoQ F3 m
m, and the measurement length was 4 mm.

[Example] The present invention will be explained based on examples.

Examples 1 to 3, Comparative Examples 1 to 6 Copolymerized polyesters having the polymer compositions shown in Table 1 were prepared to have a melt viscosity of 3000 voices! I made 10 pieces and made a beret.

The pellets of this copolyester were heated to 48°C at 90°C.
Dry under reduced pressure (3 Torr) for 1 hour, melt extrude through a slit-shaped nozzle, wrap it around a casting drum with a surface temperature of 1-30°C, cool and solidify, and form an unstretched film with a thickness of about 240 μm. made. This unstretched film was stretched 3°8 times in the potato direction at 105°C. This stretching was performed by using a difference in peripheral speed between two sets of rolls, and the stretching speed was 50,000%/min. Then, using a stenter, it was stretched 4.2 times in the width direction at 105°C at a stretching rate of 5000%/min, and immediately heat-treated at 180°C for 15 seconds under constant length to obtain a biaxially oriented film with a thickness of 15 μm. made.

Therefore, during melt extrusion, a high-precision filter NF-03C manufactured by Nippon Seimitsu Co., Ltd. was used to temporarily remove foreign substances. Further, the slit of the die was adjusted, and the thickness unevenness in the width direction of the unstretched film was 3%. The Young's modulus of the obtained biaxially oriented film was 60Qkg/m in both the potato direction and the width direction.
m2, and the sum was 1200 kg/mm2. Moreover, the melt viscosity of the film was 2700 poise.

The oxygen permeability PO2 of this film is 9CC/Tr12.
ATM・24hrS, gas barrier properties were always good.

In addition, the Charpy impact strength of this film is 35 to 9.
cm/mm2, the impact resistance was also good (Table 1, Example 1).

In addition, various films were made by changing the polymer composition, viscosity, and film forming conditions, and their gas barrier properties and impact resistance were tested (Examples 2 to 3, Comparative Examples 1 to 6).

As shown in Table 1, when the polymer composition, Young's modulus, and melt viscosity were within the range of the present invention, both gas barrier properties and impact resistance were good (Table 1, Examples 2 to 3). However, when the Young's modulus, melt viscosity ILF5, or polymer composition was outside the range of the present invention, a film having both gas barrier properties and impact resistance could not be obtained (Table 1, Comparative Examples 1 to 6).

Examples 1 to 6, Comparative Examples 7 to 13 Copolymerized polyesters having the compositions shown in Table 2 were manually condensed to a melt viscosity of 3000 poise. At this time, silica (average diameter 0° 045 μm) was added as a lubricant.
A maximum of 2ffi was added. The copolyester pellets were dried under reduced pressure (3 Torr) at 70'C for 48 hours.
L/, melt extruded from a slit-shaped nozzle, and then apply this to the surface?
! The mixture was rolled around a T30'C casting drum and cooled and solidified to produce an unstretched film with a thickness of about 110 μm.

At the time of melt extrusion, cargo was removed by filtration using a high-precision filter NF03C manufactured by Nippon'ri Co., Ltd.

Further, the slit of the die was prepared and the thickness unevenness in the width direction of the unstretched film was 3%.

This unstretched film was heated to 3.8 mm in the longitudinal direction at 105°C.
Stretched twice. This stretching was carried out using two sets of rolls with a difference in peripheral speed, and the stretching speed was 50,000%/min. Then, using a stenter, the stretching speed was 5000%/min at 125°.
Stretched 4.2 times in the width direction at 180'C, and immediately stretched 1
A biaxially oriented film with a thickness of 7 μm was produced by heat treatment at a constant length for 5 seconds.

The average surface roughness of the film at this time was 0.003 μm. Also, the sum of the Young's modulus in the longitudinal direction and the width direction is 130
It was 01q/mm2. The melt viscosity of the film is 280
There were 0 voices. By electron beam steaming on one side of this biaxially oriented film, C0-N i (Co/N i =
75. /25 weight ratio) to a thickness of 180 mm (minimum incident angle: 50°).

Thereafter, myridylic acid (methylisobutyl ketone solution) was dried on the surface of the magnetic layer for 50 minutes to form a lubricating layer of about 50 ml.

This film is slit into 8mm width and about 100m in length.
was incorporated into a 3mn1 video cassette and a durability test was conducted. This videotape ran stably despite the base film being as thin as 7 μm, and had a large output when played back.

Furthermore, the S/N ratio after continuous running was only 0.5 dB, and the durability was good.

In addition, videotapes were made with various base films having different polymer compositions, average surface roughness, and Young's modulus. When the polymer composition and Young's modulus are within the range of the present invention, and the average surface roughness is within the range of O9O○5 to 0.5 μm, durability [Table 2/Example 5] ~6
).

However, films other than those of the present invention and those having an average surface roughness of 0.
When a film outside the range of 0.005 to 0.5 .mu.m was used as a base film, no videotape with excellent durability could be produced (Table 2, Comparative Examples 7 to 13).

Claims (1)

[Claims] The following structural units (I) and (II) are combined with the following structural units (I) and (II).
A film mainly composed of a copolyester containing at least one of III) and (IV) and having a molar ratio of the structural units satisfying the following formulas (A) and (B), and
The film has a sum of Young's moduli in the longitudinal direction and width direction of 900.
A biaxially oriented copolymerized polyester film having a melt viscosity of 500 to 20,000 poise. ▲There are mathematical formulas, chemical formulas, tables, etc.▼......(I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼......(II) ▲There are mathematical formulas, chemical formulas, tables, etc.▼......(III) ▲Mathematical formulas , chemical formulas, tables, etc.▼……(IV) 0.001≦[(III)+(IV)]/(I)≦0.2…
………(A) 0.2≦(II)/[(I)+(II)+(III)+(IV)
]≦0.7……(B)