JPH0637563B2 - Polyester film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improved polyester film. More specifically, for magnetic bases,
Suitable as a film for drafting, printed circuit boards, acoustics, capacitors, gas barriers, etc. It has excellent dimensional stability and mechanical strength balance, good moldability during film formation, and good surface gloss. The present invention relates to a polyester film having properties.

[Conventional technology]

Polyester film has excellent mechanical properties, dimensional stability, heat resistance, chemical stability, and electrical properties, so it is widely used in electrical insulating materials, magnetic recording tapes, photographic films, drawing films, etc. It is applied.

As a method for producing this polyester film, a method in which a liquid crystalline polyester is extruded into a film by using a T-die or the like is conventionally known. However, in this method, when the molten liquid crystalline polyester has a tendency to molecularly orient in the extrusion direction when passing through the slit of the die, it has high strength and high strength in the machine axis direction (MD direction) of the film. Although it has an elastic modulus, it has a drawback that both strength and elastic modulus become extremely low in a direction (TD direction) perpendicular to the elastic modulus. Therefore, the obtained liquid crystalline polyester film is subject to restrictions on its use. It was

Then, as a method of improving such a defect, for example, a method of biaxially stretching a polyester exhibiting optical anisotropy in a molten state has been proposed (JP-A-55-123427). However, this method has the drawback that it is difficult to produce a film of uniform quality and the dimensional stability of the obtained film is poor, and it cannot be said to be a fully satisfactory method.

[Problems to be solved by the invention]

The object of the present invention is to improve the drawbacks of such a conventional liquid crystalline polyester film, to have excellent balance of dimensional stability and mechanical strength, good moldability during film formation, and good surface gloss. The object is to provide a polyester film having properties.

[Means for solving problems]

The present inventors have conducted intensive studies to develop a polyester film having the above-mentioned excellent properties, and as a result, a polyester exhibiting optical anisotropy in a molten state has polyalkylene terephthalate oriented in a specific ratio. It has been found that the objective can be achieved by uniaxially or biaxially stretching a film formed by forming a resin composition, and the present invention has been completed based on this finding.

That is, the present invention provides a resin film containing (A) 5 to 98% by weight of a polyester showing optical anisotropy in a molten state and (B) 95 to 2% by weight of a polyalkylene terephthalate in the machine axis direction and And / or a polyester film characterized by being stretched in a direction perpendicular to the machine axis.

Hereinafter, the present invention will be described in detail.

The polyester exhibiting optical anisotropy in the molten state as used herein is a polyester having a property of transmitting polarized light in an optical system including a polarizer in which a polymer in a molten state intersects at 90 °.

In the film of the present invention, it is necessary to use a polyester that exhibits optical anisotropy in the molten state as the component (A). This polyester can be prepared by various methods such as (1) aromatic dicarboxylic acid and / or aliphatic dicarboxylic acid and a lower fatty acid ester (eg, acetic acid ester) of a dioxyaromatic compound, if necessary, with p-oxybenzoic acid. Heat polymerization with lower fatty acid ester of aromatic oxycarboxylic acid such as acid (eg acetic acid ester), (2) Need aryl ester of aromatic dicarboxylic acid and / or aliphatic dicarboxylic acid (eg phenyl ester) Aromatic oxycarboxylic acid aryl ester (for example, phenyl ester) and / or diphenyl carbonate and other diaryl carbonate according to the method of heat polymerization, (3) aromatic dicarboxylic acid and / or aliphatic dicarboxylic acid and dioxy aromatic If necessary, A method of reacting with a group aryloxycarboxylic acid, for example, a diaryl carbonate such as diphenyl carbonate, and then heat-polymerizing the reaction mixture, (4) terephthalic acid, diphenoxyethane-4,4'-dicarboxylic acid, naphthalene-2,6 −
A polyester of an aromatic dicarboxylic acid such as dicarboxylic and an aliphatic or alicyclic glycol such as ethylene glycol or cyclohexane-1,4-dimethanol,
(A) Lower fatty acid ester (for example, acetic acid ester) of the aromatic dicarboxylic acid and a dioxy aromatic compound such as methylhydroquinone and chlorohydrodroquinone
And (b) a lower fatty acid ester (for example, acetic acid ester) of an aromatic oxycarboxylic acid such as p-oxybenzoic acid can be heat-polymerized.

In these polymerization methods, a small amount of a conventionally known transesterification catalyst may be added to accelerate the reaction, if necessary. The polymerization conditions are preferably 200-
It is advantageous to carry out the melt polymerization at a temperature in the range of 380 ° C. under normal pressure or reduced pressure, usually under reduced pressure of 100 to 0.01 mmHg.

Suitable polyesters obtained by such a polymerization method include, for example, (a) the general formula (Wherein R ₁ is a hydrogen atom, a halogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group or an aryloxy group), and 9 to 42 mol% of the repeating unit represented by the formula (b). (N in the formula is an integer of 1 to 20) the repeating unit of 9 to 42 mol%, and (c)
General formula (In the formula, R ₂ is a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group having 1 to 4 carbon atoms, or an aryloxy group) and contains 16 to 82 mol% of repeating units, and has a logarithmic viscosity number. Aromatic polyester resins of 0.8 or more are included.

In this aromatic polyester resin, as R ₁ of the repeating unit (a) represented by the general formula (I), hydrogen atom, chlorine atom, fluorine atom, methyl group, ethyl group, methoxy group, ethoxy group, Phenoxy and naphthoxy groups are preferred. Moreover, as n of the repeating unit (b) shown by the said General formula (II), the integer of 1-4 is preferable. Further, as R ₂ of the repeating unit (c) represented by the general formula (III), similar to R ₁ , hydrogen atom, chlorine atom, fluorine atom, methyl group, ethyl group,
Phenoxy and naphthoxy groups are preferred.

The optimum combination of the repeating units (a), (b) and (c) is -O-CH ₂ -CH ₂ -O- and Is.

In this aromatic polyester resin, the content ratio of each repeating unit (a), (b) and (c) is 9 to 42 mol%, 9 to 42 mol% and 16 to 82 mol%, respectively, (C) The content of the repeating unit is important. When the content is less than 16 mol%, the aromatic polyester does not form a liquid crystal, and when the content exceeds 82 mol%, a liquid crystal is formed but the moldability is deteriorated. Is not preferred. Further, this aromatic polyester has a logarithmic viscosity number of 0.80 or more, preferably 0.50 or more, measured at 30 ° C. with respect to a solution obtained by dissolving 0.5 g of this aromatic polyester in 100 m of a mixed solution of phenol and tetrachloroethane (volume ratio 3: 2). It is 0.85 or more. In addition, such an aromatic polyester may be prepared by applying an ordinary method, or a commercially available product such as X7G manufactured by Eastman Kodak Company may be used.

In the film of the present invention, it is necessary to use polyalkylene terephthalate as the component (B). This polyalkylene terephthalate is a polyester obtained by a condensation reaction containing a dicarboxylic acid component in which at least 40 mol% of the dicarboxylic acid component is terephthalic acid and a diol component as main components. Examples of the carboxylic acid component other than terephthalic acid include aliphatic dicarboxylic acids having 2 to 20 carbon atoms such as azelaic acid, sebacic acid, adipic acid and dodecanedicarboxylic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, diphenyl. −
4,4'-dicarboxylic acid, diphenylethane-4,4 '
-Aromatic dicarboxylic acids such as dicarboxylic acids or alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, either alone or as a mixture. The diol component may be an aliphatic glycol having 2 to 20 carbon atoms, such as ethylene glycol, propylene glycol or 1,4-
Butanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, decamethylene glycol, cyclohexanedimethanol, cyclohexanediol, etc., or molecular weight 400-600
0 long chain glycols, such as polyethylene glycol,
Poly-1,4-propylene glycol, polytetramethylene glycol, a glycol of a copolymer of ethylene oxide and propylene oxide, or one end of these is linked to an alkyl group, an aryl group, an araryl group or the like by an ester bond, an ether bond or the like. Derivatives and mixtures thereof may be mentioned. Specific examples of the polyalkylene terephthalate include polyethylene terephthalate, polypropylene terephthalate, polyhexamethylene terephthalate, and polycyclohexane dimethylene terephthalate. Among these, polybutylene terephthalate and polyethylene terephthalate having an intrinsic viscosity of 0.5 or more are particularly preferable.

Regarding the content ratio of the polyester showing optical anisotropy in the molten state of the component (A) and the polyalkylene terephthalate of the component (B) in the film of the present invention, (A)
It is necessary that the components are in the range of 5 to 98% by weight and the component (B) is in the range of 95 to 2% by weight. When the content of the component (B) is less than 2% by weight, the dimensional stability is poor and it is difficult to make the quality uniform, while when it exceeds 95% by weight, the mechanical strength and the dimensional stability are deteriorated. Further, the film in which the ratio of the component (A) and the component (B) is within the above range, the component (A) having a negative linear expansion coefficient with respect to the orientation direction,
The linear expansion coefficient is extremely small due to the interaction with the component (B) having the positive coefficient.

The film of the present invention is obtained by forming a film of a resin composition containing the component (A) and the component (B) in a predetermined ratio to obtain an original film of a film, and then uniaxially or biaxially extending the original film of the film. Can be manufactured by. If necessary, various fillers can be added to the resin composition in an amount of usually 60% by weight or less. Examples of the resin filler include glass fiber, asbestos, carbon fiber, amorphous carbon fiber, synthetic polymer fiber, aluminum fiber, aluminum silicate fiber, aluminum oxide fiber, titanium fiber, magnesium fiber, rock wool fiber, Fibers such as steel fiber, tungsten fiber, cotton, wool, and wool cellulose fiber, or calcium silicate, silica,
Examples include clay, talc, mica, polytetrachloroethylene, graphite, aluminum trihydrate, sodium aluminum carbonate, barium ferrite and the like. Further, to the resin composition, additives usually used for polyester type resin compositions, for example, antioxidants, ultraviolet absorbers, pigments, dyes, plasticizers, antistatic agents and the like are added as desired. You can also

Film formation of this resin composition is performed by a melt extrusion method such as a cast roll method, an inflation method, or a tubular method. At this time, the melt extrusion temperature is usually 200 to
The temperature is selected in the range of 350 ° C., preferably 220 to 320 ° C., and the cooling and solidifying temperature is adjusted so as not to crystallize. Further, the lip opening is usually in the range of 0.01 to 2 mm.

The film formed in this manner can be subjected to a machine axis direction (MD direction) or a direction perpendicular to the machine axis (TD direction) by a conventionally used stretching method such as a tenter method, a tubular method, or a multistage stretching method. ), Or biaxially in the machine axis direction and in the direction perpendicular to the machine axis. The stretching temperature is usually 50 to 200 ° C., preferably 60.
It is in the range of to 130 ° C. Regarding the draw ratio,
In the case of uniaxial stretching (TD direction), it is usually 1.5 to 8 times, and in the case of biaxial stretching (TD direction and MD direction), it is usually 1.2.
It is selected in the range of up to 6 times. The uniaxially stretched film has a balanced mechanical strength and improved dimensional stability, and the biaxially stretched film has a enhanced mechanical strength and a balanced dimensional stability. Further, in the present invention, if desired, it may be biaxially stretched and then further uniaxially stretched.

Preferable examples of the stretched film include 5 to 98% by weight of the component (A) and 95 to 2% by weight of the component (B), particularly 20 to 95% by weight of the component (A) and 80 to 5 of the component (B).
A resin film containing 100% by weight is magnified in the TD direction.
A film uniaxially stretched 1.5 to 8 times, especially 2 to 6 times,
Component (A) 5 to 60% by weight and component (B) 95 to 40
% By weight, in particular 10 to 50% by weight of component (A) and (B)
The film containing 90 to 50% by weight of the component is TD
Examples include a film biaxially stretched in the machine direction and the MD direction at a magnification of 1.2 to 6 times, particularly 1.5 to 4.5 times.

In the present invention, the film thus uniaxially or biaxially stretched can be heat-treated as necessary. The heat treatment is usually carried out by heating the stretched film as it is or by heating it for 1 second or longer, preferably for 10 seconds to 10 minutes at a temperature in the range of 150 to 300 ° C. while subjecting it to limited shrinkage or stretching. . This heat treatment improves the crystallinity of the film and makes it more excellent in mechanical strength, heat resistance, dimensional stability and the like.

There is no particular limitation on the thickness of the film of the present invention,
It is usually selected in the range of 1 to 1000 μm, preferably 10 to 300 μm.

The polyester film of the present invention thus obtained is excellent in balance of dimensional stability and mechanical strength, and
It has good moldability during film formation and has good surface glossiness. For example, for magnetic bases, drafting, printed circuit boards,
It is preferably used as a film for audio, condenser, gas barrier, etc.

〔Example〕

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

The physical properties of the film were determined as follows.

(1) Density Based on JIS-K-7112, it was determined by the density gradient tube method.

(2) Linear expansion coefficient Using a thermal analysis device manufactured by Seiko Denshi KK, -100
The measurement was carried out at a temperature in the range of -100 ° C, and the value in the temperature range of 0-50 ° C was adopted.

The sample length was 20 mm × 5 mm, the heating rate was 40 ° C./min, and the load was 10 g.

(3) Tensile elastic modulus, tensile breaking strength It was determined according to JIS-K-2318.

(4) Element Riff Tensile Strength Obtained in accordance with JIS-Z-1702.

The abbreviations of polyester and polyalkylene terephthalate used have the following meanings.

PHB60: polyester manufactured by Eastman Kodak Co., Ltd. “X7G”, logarithmic viscosity number 0.75, repeating unit (a) 4
0 mol%, (b) 40 mol%, (c) 60 mol% PHB80: polyester manufactured by Eastman Kodak Company "X7G" vs. viscosity index 0.80, repeating unit (a) 2
0 mol%, (b) 20 mol%, (c) 80 mol% PET: Mitsubishi Rayon Co., Ltd., trade name "MA523"
Intrinsic viscosity 0.75 dl / g PBT: Product name "MA523" manufactured by Polyplastics Co., Ltd.,
Intrinsic Viscosity 1.06 Examples 1 to 8 and Comparative Examples 1 to 9 As the polyester as the component (A) and the polyalkylene terephthalate as the component (B), those shown in a separate table are used.
These were mixed in the proportions shown in the table and pelletized using a twin-screw kneader.

Next, the pellets are fed to a 30 mmφ extruder, the die temperature is 290 ° C., the lip opening is 0.7 mm, the air gap is 5 mm.
Extruded from a T-die with a width of 200 mm under the above conditions and taken up by a cast roll at a speed of 1 to 20 m / min, and a thickness of 100 μm
I got the original fabric.

Next, the raw film was stretched at a predetermined ratio using a biaxial stretching machine, and the obtained film was fixed on a metal frame of 30 cm square and heat-treated at 220 ° C. for 1 minute. However,
In Comparative Example 2, heat treatment was performed at 180 ° C.

The physical properties of the film thus obtained were measured and shown in the table.

[Effects of the Invention] As described above, the polyester film of the present invention is a uniaxial or biaxial resin film containing a polyester and polyalkylene terephthalate exhibiting optical anisotropy in a molten state in a predetermined ratio. It is axially stretched, has excellent dimensional stability and mechanical strength balance, has good moldability at the time of film formation, and has good surface glossiness, and has an extremely high commercial value.

Claims (1)

[Claims] 1. A resin film containing (A) 5 to 98% by weight of a polyester showing optical anisotropy in a molten state and (B) 95 to 2% by weight of a polyalkylene terephthalate, in a machine axis direction and / or Alternatively, a polyester film which is drawn in a direction perpendicular to the machine axis.