JPH09309961A - Polyester film and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-quality polyester film having a high Young's modulus. few surface defects, and a low oligomer content and a process for producing the same. SOLUTION: This polyester film comprises a non-liq.-crystal polyester, a liq.-crystal polyester. and a compatibilizer having a melt viscosity lower than that of the non-liq.-crystal polyester. This production process is characterized in that a non-liq.-crystal polyester. a liq.-crystal polyester, and a compatibilizer having a melt viscosity lower than that of the non-liq.-crystal polyester are blended and formed into a film.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a film in which physical properties and quality of a conventional polyester film are significantly improved,
Specifically, the present invention relates to a polyester film having a high Young's modulus, toughness, a low oligomer content, a low thermal decomposition gel content, and excellent electrical characteristics.

[0002]

2. Description of the Related Art As one method of increasing Young's modulus, a method of increasing the degree of molecular orientation by improvement such as stretching is generally performed. As another method, international publication WO8
No. 7-05919, republication, Japanese Patent Publication No. 37577, JP-A-57-25354, and the like, a compound having a high Young's modulus such as a liquid crystalline polyester is finely dispersed in a non-liquid crystalline polyester. There is a method of dispersing and reinforcing and strengthening.

However, in order to increase the Young's modulus,
Excessive molecular orientation causes non-liquid crystalline polyester (A)
Insufficient adhesion at the interface between the liquid crystalline polyester (B) and the liquid crystalline polyester (B) causes many voids during stretching, resulting in frequent film breakage and deterioration of physical properties such as electrical properties of the obtained film. was there.

In addition, when the liquid crystalline polyester is in a fibrous form, the Young's modulus is significantly improved.
As disclosed in Japanese Patent Publication No. 37577, the liquid crystal polyester melt immediately after being extruded from an extruder that gives a high shear rate of 200 sec ^-1 or more often has a fibrous morphology. , If the shear rate is reduced to 10 seconds ^-1 or less, for example, by passing through a filter, even if it is a fiber shape immediately after extrusion, the shape will be changed to a spherical shape, and as a result, the expected shape will be obtained. There was a problem that the Young's modulus could not be improved.

There have been many reports on compatibilizers for non-liquid crystalline polyesters and liquid crystalline polyesters which are closely related to these problems. Japanese Patent Laid-Open No. 2-18
Japanese Patent Publication No. 2762 discloses that a fibril resistance and mechanical properties are improved by adding a third component as a compatibilizing agent to a composite of a liquid crystalline polyester and a non-liquid crystalline polyester. Japanese Unexamined Patent Publication (Kokai) No. 4-28768 describes a compatibilizing agent having both components of a liquid crystalline polyester and a non-liquid crystalline polyester as a partial chain. Further, JP-A-4-88063, JP-A-6-41444,
JP-A-6-256489 also describes addition of a compatibilizer. The use of two kinds of liquid crystalline polyesters is also disclosed in JP-A-7-233310.

However, the compatibilizers disclosed in these inventions cannot necessarily be effectively used for all polymer systems and manufacturing processes. Further, in these inventions according to the prior art, selection of a concrete and effective compatibilizing agent in consideration of the melt viscosity of the polymer has not been examined.

[0007]

The object of the present invention is to find an effective compatibilizing agent selection method that overcomes the above-mentioned conventional state of art and problems, and has a high Young's modulus and a small amount of surface defects and oligomers. To obtain high quality polyester film.

[0008]

In order to solve the above problems, the inventors of the present invention have extensively studied a compatibilizing agent for a non-liquid crystalline polyester and a liquid crystalline polyester. as a result,
Surprisingly, by using a compatibilizer having a specific melt viscosity and structure, the adhesion at the interface between the non-liquid crystalline polyester and the liquid crystalline polyester is improved, and the L / D of the fiber shape of the liquid crystalline polyester is improved. The present invention was completed by finding that the Young's modulus of a polyester film is improved, and that the shear heat generation of the polymer in the melt extrusion process is suppressed to obtain a high-quality polyester film with a small amount of surface defects and oligomers. Came to let.

That is, the polyester film of the present invention comprises a non-liquid crystalline polyester (A), a liquid crystalline polyester (B), and a compatibilizer (C) having a melt viscosity lower than that of the non-liquid crystalline polyester (A). It is a polyester film characterized in that.

The film of the present invention to which such a compatibilizer having a low melt viscosity is added has a high total Young's modulus, that is, a sum of Young's moduli in the machine axis direction (MD) and the width direction (TD) of 1300 to 2500. Level mechanical characteristics,
At the same time, the fish eye has a high level of 3 (pieces / 10 cm ² ) or less and an oligomer amount of 0.45% or less. Although it depends on the intrinsic viscosity of the polyester and the stretching ratio at the time of film formation, in the conventional biaxially stretched polyester film, the total Young's modulus is at most 800 to 1200, and the fish eye and the amount of oligomer are 5 (pieces / 10
cm ² ) or more and the amount of oligomer was 0.45%, the present invention is epoch-making, and according to the present invention, a polyester film having high mechanical properties and high quality can be obtained. You can do it.

Further, the method for producing a polyester film of the present invention comprises a non-liquid crystalline polyester (A), a liquid crystalline polyester (B) and a compatibilizer (C) having a lower melt viscosity than the non-liquid crystalline polyester (A). ) Is blended to form a film.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The liquid crystalline polyester (B) used in the present invention is a melt-moldable polyester having a mesogenic group in the main chain and having a liquid crystal forming property, such as an aromatic oxycarbonyl unit, Examples thereof include polyesters that form an anisotropic melt phase composed of structural units selected from aromatic dioxy units, aromatic dicarbonyl units, alkylenedioxy units, and the like.

Examples of preferable liquid crystalline polyesters used in the present invention include the following (I), (II), (III),
And a liquid crystalline polyester comprising the structural units of (IV),
One or more selected from liquid crystalline polyesters composed of structural units (I), (III) and (IV), and liquid crystalline polyesters composed of structural units (I), (II) and (IV). .

[0014]

Embedded image (However, R ₁ in the formula is

Embedded image And R ₂ is

[Chemical 6] R ₃ represents one or more groups selected from

[Chemical 7] Represents one or more groups selected from In the formula, X represents a hydrogen atom or a chlorine atom, and the structural unit [(II) + (III
)] And the structural unit (IV) are substantially equimolar.

The above-mentioned structural unit (I) is the structural unit of the polyester produced from p-hydroxybenzoic acid and / or 6-hydroxy-2-naphthoic acid.
I) is 4,4'-dihydroxybiphenyl, 3,3
′, 5,5′-Tetramethyl-4,4′-dihydroxybiphenyl, hydroquinone, t-butylhydroquinone, phenylhydroquinone, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 2,2 ′ -Bis (4-hydroxyphenyl) propane and 4,4 '
A structural unit produced from an aromatic dihydroxy compound selected from dihydroxydiphenyl ether, a structural unit (III) is a structural unit produced from ethylene glycol, a structural unit (IV) is terephthalic acid, isophthalic acid,
4,4'-diphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,2-bis (phenoxy) ethane-
4,4'-dicarboxylic acid, 1,2-bis (2-chlorophenoxy) ethane-4,4'-dicarboxylic acid and 4,
Each of the structural units formed from an aromatic dicarboxylic acid selected from 4′-diphenyl ether dicarboxylic acid is shown.

In the case of a liquid crystal polyester composed of the above structural units (I), (II) and (IV), R ₁ is

Embedded image And R ₂ is

Embedded image And at least one selected from the R ₃

Embedded image Those which are at least one kind selected from

Further, in the case of the liquid crystal polyester comprising the above structural units (I), (III) and (IV), R ₁ is

Embedded image And R ₃ is

[Chemical 12] Is particularly preferred.

The above structural units (I), (II) and (II
In the case of liquid crystal polyester consisting of (I) and (IV),
R ₁ is

Embedded image And R ₂ is

Embedded image And R ₃ is

Embedded image Is particularly preferred.

The copolymerization amount of the above structural units (I), (II), (III) and (IV) may be arbitrary, but fluidity,
From the viewpoint of compatibility with the non-liquid crystalline polyester, the following copolymerization amount is preferable.

That is, in the case of a liquid crystalline polyester composed of the structural units (I), (II) and (III), the structural unit (I) is 15 to 90 of [(I) + (II)].
Mol% is preferable, 50-80 mol% is more preferable,
Most preferably, it is 55 to 75 mol%. The structural unit (IV) is substantially equimolar to the structural unit (II).

In the case of a liquid crystalline polyester composed of the structural units (I), (III) and (IV), the structural unit (I) is 30 to 95 mol% of [(I) + (III)]. Is preferred, 40-80 mol% is more preferred, and 50
~ 75 mol% is most preferred. The structural unit (IV) is substantially equimolar to the structural unit (III).

Further, the structural units (I), (II),
In the case of the liquid crystalline polyester composed of (III) and (IV), the molar fraction of [(I) + (II)] with respect to the above structural unit [(I) + (II) + (III)] is 40 to 85. Mol%
Is preferable, and 60-80% is more preferable. The molar fraction of (III) with respect to the structural unit [(I) + (II) + (III)] is preferably 60 to 15 mol%, more preferably 40 to 20 mol%. The molar ratio of the structural units (I) / (II) is preferably from 75/25 to 95 / from the viewpoint of fluidity.
5, more preferably 78/22 to 93/7. Further, the number of moles of the structural unit (IV) is the structural unit [(II)
+ (III)].

The term "substantially" in the above description means that the number of the terminal groups of the polyester can be either carboxylic xyl group terminals or hydroxyl terminal groups, if necessary. This is because the number of moles of the structural unit (IV) is not completely equal to the total number of moles of the structural unit [(II) + (III)].

In the polycondensation of the preferred liquid crystalline polyester, in addition to the components constituting the structural units (I) to (IV), 3,3'-diphenyldicarboxylic acid, 2,2 '
-Aromatic dicarboxylic acids such as diphenyldicarboxylic acid,
Aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, alicyclic dicarboxylic acids such as hexahydroterephthalic acid, chlorohydroquinone, methylhydroquinone, 4,4'-dihydroxydiphenylsulfone, 4,4 ' -Dihydroxydiphenyl sulfide, aromatic diol such as 4,4'-dihydroxybenzophenone, 1,4-butanediol, 1,
6-hexanediol, neopentyl glycol, 1,
Aliphatic and alicyclic diols such as 4-cyclohexanediol, 1,4-cyclohexanedimethanol and aromatic hydroxycarboxylic acids such as m-hydroxybenzoic acid and 2,6-hydroxynaphthoic acid, and p-aminophenol, p- Aminobenzoic acid or the like can be further copolymerized in a small proportion within a range that does not impair the effects of the present invention.

The liquid crystalline polyester in the present invention can be produced according to a conventional polyester polycondensation method.

For example, in the above-mentioned preferred method for producing a liquid crystalline polyester, the structural unit (III) is used.
When the compound does not contain (1) and (2), the following (3) production method is preferable when the compound contains the structural unit (III).

(1) p-acetoxybenzoic acid and 4,
A method of producing from a diacylated aromatic dihydroxy compound such as 4'-diacetoxybiphenyl, 4,4'-diacetoxybenzene and an aromatic dicarboxylic acid such as terephthalic acid by a deacetic acid polycondensation reaction.

(2) p-hydroxybenzoic acid and 4,
A method of reacting an aromatic dihydroxy compound such as 4'-dihydroxybiphenyl and hydroquinone, and an aromatic dicarboxylic acid such as terephthalic acid with acetic anhydride to acylate a phenolic hydroxyl group, followed by a deacetic acid polycondensation reaction.

(3) In the presence of a bis (β-hydroxyethyl) ester of an aromatic dicarboxylic acid such as a polyester polymer such as polyethylene terephthalate, an oligomer, or bis (β-hydroxyethyl) terephthalate. The method of manufacturing by the method of.

Although these polycondensation reactions proceed without a catalyst, in some cases it may be preferable to add stannous acetate, tetrabutyl titanate, potassium acetate and sodium acetate, antimony trioxide, metallic compounds such as metallic magnesium. .

In the present invention, a low-viscosity liquid crystalline polyester, that is, a liquid crystalline polyester which increases the melt viscosity ratio (melt viscosity of non-liquid crystalline polyester (η _A ) / melt viscosity of liquid crystalline polyester (η _B )) is preferable. . This is because the object of the present invention, in particular, the suppression of heat generation by shearing in the extrusion step can be achieved more effectively as in the case where a low-viscosity liquid crystalline polyester is added to the non-liquid crystalline polyester.
The melt viscosity ratio is desirably at least 5 or more, preferably 10 or more, more preferably 50 or more, and particularly preferably 500 or more. According to the findings of the present inventors, 500 to 100,000 is most preferable. Therefore, although the melt viscosity of the liquid crystalline polyester depends on the melt viscosity of the non-liquid crystalline polyester used, the melting point of the non-liquid crystalline polyester constituting the matrix +15
Under conditions of a temperature of 100 ° C. and a shear rate of 100 sec ⁻¹ , the pressure is desirably about 200 Pa · sec or less, preferably 50 Pa · sec or less, and more preferably 10 Pa · sec or less. A liquid crystal polyester having such a low melt viscosity and which can be particularly preferably used in achieving the object of the present invention,
A liquid crystalline polyester comprising the above structural units (I 1), (II), (III) and (IV). This liquid crystalline polyester is particularly effective in finely dispersing it in the non-liquid crystalline polyester to enhance the quality and characteristics of the polyester film.

The dispersion form of the liquid crystalline polyester in the polyester film may be any form such as skin / core type, sea-island type, multi-layer type, fiber type and the like, and is not particularly limited, but in the present invention, the liquid crystalline polyester is It is preferably finely dispersed in a fibrous state in the polyester film. In this case, the diameter of the liquid crystalline polyester fiber is 3
It is less than or equal to μm, preferably less than or equal to 1 μm, more preferably less than or equal to 0.5 μm, and particularly preferably less than or equal to 0.2 μm. The aspect ratio of the liquid crystalline polyester fiber is 1
It is 0 or more, preferably 50 or more, more preferably 100 or more. The amount of the liquid crystalline polyester added is not particularly limited, but is 0.1 to 40% by weight, preferably 0.3 to 20% by weight, and more preferably 0.5 to 1% by weight based on the total weight of the polymer.
The range of 0% by weight is preferable. If the amount added is less than 0.1% by weight, it is difficult to obtain a high-strength film, and if it exceeds 40% by weight, the surface of the polyester film becomes very rough, which is not preferable.

Typical examples of the non-liquid crystalline polyester (A) that can be used in the present invention include polyethylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate, polyethylene naphthalate, polycyclohexane dimethylene terephthalate, and their copolyesters. There is coalescence etc. Of course, polyesters having an ether component in the main chain, for example, copolymers of diethylene glycol, triethylene glycol, polyethylene glycol, polytetramethylene glycol and the like may be used. In the case of the present invention, polyethylene terephthalate and polyethylene naphthalate having an intrinsic viscosity of 0.8 or more, preferably 1.0 or more, more preferably 1.2 or more are preferable. When the intrinsic viscosity of the non-liquid crystalline polyester is large, the melt viscosity ratio (η _A / η _B ) is large, and as a result, it is possible to effectively realize the shear heat generation in the extrusion process. Further, in this case, the liquid crystalline polyester is finely dispersed in the film, and the L / D of the liquid crystalline polyester fiber formed at this time is also increased, so that the Young's modulus of the film is increased and the polyester film of the present invention is obtained. It is preferable above. The solid phase polymerization method is most preferably used as a means for obtaining such a non-liquid crystalline polyester having a high intrinsic viscosity. The melting point of the non-liquid crystalline polyester is preferably equal to or higher than that of the liquid crystalline polyester, because the liquid crystalline polyester is likely to be finely dispersed in the fibrous state in the non-liquid crystalline polyester.

The compatibilizing agent (C) used in the present invention is melt-moldable and has a lower melt viscosity than the non-liquid crystalline polyester (A), and is compatible with the non-liquid crystalline polyester (A) and the liquid crystalline polyester (B). There is no particular limitation as long as it is a compatible polymer or oligomer, but a polymer having a mesogen group in its main chain is preferable. In this case, the mole fraction of the mesogen group in the compatibilizing agent is preferably 5 to 50 mol%, more preferably 10 to 40 mol%, further preferably 15 to 35 mol%. As the compatibilizer (C), at least one selected from various liquid crystal polyesters, liquid crystal polyester amides, or polymers containing a mesogenic group thereof can be used.

In the present invention, a low-viscosity type compatibilizer can be preferably used as in the liquid crystalline polyester. In this case, the melt viscosity ratio (η _C / η _B ) of the liquid crystalline polyester (B) and the compatibilizer (C) is preferably 0.1 to 5, more preferably 0.5 to 2, and most preferably 0.1. 75-
It is 1.5. When the melt viscosity ratio η _C / η _B is 1, that is, when the liquid crystal polyester and the compatibilizer have the same melt viscosity, it is possible to more effectively achieve the object of the present invention, particularly, the suppression of shearing heat generation in the extrusion step. Because you can. Melt viscosity ratio of non-liquid crystalline polyester (A) and compatibilizer (C) (η _A
/ Η _C ) depends on the melt viscosity of the liquid crystalline polyester (B) used, but like the melt viscosity ratio (η _A / η _B ),
It is preferably at least 5 or more, more preferably 10 or more, more preferably 50 or more, and particularly preferably 500 or more. According to the findings of the present inventors,
Most preferably, it is 500 or more and 500,000 or less. The amount of the compatibilizer (C) added is not particularly limited, but is in the range of 0.01 to 5% by weight, preferably 0.1 to 3% by weight, and more preferably 0.5 to 1% by weight based on the total weight of the polymer. Is good. If the added amount is less than 0.01% by weight, it tends to be difficult to improve the characteristics and quality of the film.
On the other hand, if it exceeds 5% by weight, only the compatibilizing agent in the polyester film is likely to undergo phase separation, and the function as the compatibilizing agent is reduced, which is not preferable.

In the polyester film of the present invention, a plasticizer other than the liquid crystalline polyester and the non-liquid crystalline polyester may be used as long as the effect of the present invention is not impaired.
A weathering agent, an antioxidant, a heat stabilizer, a lubricant, an antistatic agent, a whitening agent, a coloring agent, a conductive agent and the like may be added.

The polyester film of the present invention may be a single film, but may be formed by laminating another polymer layer, for example, polyester, polyolefin, polyamide, polyvinylidene chloride, an acrylic polymer or the like on this. Especially when the polyester layer is laminated thinly on the surface layer,
The thickness (M) of the laminated portion is made smaller than the average diameter (N) of the particles contained in the laminated portion (M <N), preferably 1/1000 to 1/2 of M, more preferably , 1
By setting the ratio to / 100 to 1/10, a film excellent in running property, slipperiness, and smoothness can be obtained, and it is particularly preferable as a base film for magnetic recording in which surface characteristics are important. Further, in the case of a laminated film of three or more layers made of polyester, productivity and quality can be improved by mixing a recovered material and the like in the central layer.
Such particles include silicon oxide, magnesium oxide, calcium carbonate, titanium oxide, aluminum oxide,
Cross-linked polyester, cross-linked polystyrene, mica, talc, kaolin and the like can be used, but are not limited thereto.

The polyester film of the present invention may be an unstretched or non-oriented film, but it may be uniaxially or biaxially stretched, and may further be made into a heat-fixed oriented film to have high elasticity, toughness, heat resistance and low oligomer. Further, effects such as electric characteristics can be more remarkably exhibited.

Next, a method for producing the polyester film of the present invention will be described, but the present invention is not limited to such an example.

Here, an example in which polyethylene terephthalate is used as the non-liquid crystalline polyester (A) is shown, but the production conditions differ depending on the polyester used. According to a conventional method, bis-β-hydroxyethyl terephthalate (BHT) is obtained by esterifying terephthalic acid and ethylene glycol or transesterifying dimethyl terephthalate and ethylene glycol. Next, while transferring the BHT to the polymerization tank, the polymerization reaction is advanced by heating to 280 ° C. under vacuum. Here, a polyester having an intrinsic viscosity of about 0.5 is obtained. The obtained polyester is subjected to solid-state polymerization in a pellet form under reduced pressure. In the case of solid-phase polymerization, pre-crystallize at a temperature of 180 ° C or lower in advance, and then
10-50 under reduced pressure of about 1 mmHg at 90-250 ° C
The solid phase polymerization is carried out for a period of time, and the degree of polymerization is increased so as to be 5 times or more the melt viscosity of the liquid crystal polyester (B) used.

Next, the high-viscosity polyethylene terephthalate, the liquid crystalline polyester (B) and the compatibilizer (C).
Blended raw materials, raw materials obtained by melting and uniformly mixing these raw materials, further, raw materials recovered from the film of the present invention alone, or raw materials obtained by appropriately mixing the above two to three types of raw materials at 180 ° C. for 3 hours After vacuum-drying above, under a nitrogen stream or under vacuum so that the intrinsic viscosity does not decrease.
The film is supplied to an extruder heated to 80 ° C., and a film is formed by a known method. At this time, of course, the higher the shear rate in the extruder is 20 sec ^-1 or more, preferably 50 sec ^-1 or more, the smaller the dispersion diameter of the liquid crystalline polyester (B) in the extruder becomes, and a small amount of compatibilization occurs. The agent is preferable because the effect of the present invention becomes large, but if the shear rate is increased to 300 sec ^-1 or more, the polymer is thermally decomposed due to heat generated by shearing, which is not preferable. Further, it is preferable to use various filters such as sintered metal, porous ceramics, sand, and wire netting in order to remove foreign matters. At this time, the shear rate at the time of passing through the filter is as low as 10 seconds ^-1 or less, and the pressure at the time of passing through the filtration does not become remarkably low by adding only the liquid crystal component,
The addition of the compatibilizer of the present invention makes it possible to reduce the pressure during filtration to a practical range.

The draft ratio when extruded into a sheet by a T die is preferably 10 to 200, more preferably 15
By setting it to 100, the fibrous dispersion diameter of the liquid crystal polyester is reduced, and the aspect ratio (L / D), which is the ratio of the fiber length (L) and the diameter (D), is preferably 10 to 1000, More preferably, it is 100 to 700, and even more preferably 150 to 500.
Then, cast the sheet-shaped cast film at 80 to 150 ° C.
Is heated by a heating roll group of 1), stretched in the longitudinal direction 2 to 7 times in a single stage or in multiple stages of 2 stages or more, and cooled by a cooling roll group of 20 to 50 ° C. Then, while guiding the film to a normal tenter and gripping both ends of the film with clips, 80 to 15
Heat in a hot air atmosphere heated to 0 ° C.
Stretch 6 times. Subsequently, the film is heated to 150 to 250 ° C.
Heat fix at the temperature of The heat setting may be performed under tension, and in order to further improve the thermal dimensional stability, relaxation in the width direction is also preferably performed. Further, if necessary, re-longitudinal stretching and / or re-lateral stretching can be performed before heat setting.

[0043]

[Methods for measuring physical properties and evaluating effects]

(1) Intrinsic viscosity It is a value measured at a concentration of 0.1 g / ml in orthochlorophenol at 25 ° C. Since the liquid crystalline polyester does not dissolve in orthochlorophenol, the measurement was performed after removing the polymer by centrifugation.

(2) Melt viscosity Using a high-lower flow tester, 280 ° C., shear rate 1
Measure the value at 00 seconds- ¹ . The unit is represented by [Pa · sec].

(3) Young's modulus Tensilon-type tensile test (manufactured by Orientec Co.) has a width of 10
mm, the length between chucks was set to 100 mm, and a tensile test was carried out at a tensile rate of 200 mm / min in an atmosphere of 23 ° C. and 65% RH to obtain a value.

(4) Fisheye (FE) A film of 10 cm ² was placed under crossed Nicol polarized light, and in the entire image, a glittering part having a different major color had a major axis of 10 μm or more. I counted. The unit is shown in pieces / cm ² .

(5) Amount of oligomer 100 mg of the polymer was dissolved in 1 ml of o-chlorophenol and subjected to liquid chromatography (model 8500, VA).
RIAN). It is expressed in% by weight with respect to the polymer.

(6) Fiber Diameter and Aspect Ratio of Liquid Crystalline Polyester The film was dissolved using orthochlorophenol,
Unmelted liquid crystalline polyester is separated by centrifugation,
Using a scanning microscope, liquid crystalline polyester fiber 100
Observe and ask for the individual. The aspect ratio is the ratio (L / D) of the length (L) in the longest direction of the liquid crystalline polyester fiber and the length (D) of the thickest part orthogonal to it.
Further, D is the fiber diameter.

[0049]

EXAMPLES The present invention will be described based on examples and comparative examples.

Example 1 As an amorphous polyester, an intrinsic viscosity of 0.8 (dl /
The polyethylene terephthalate raw material of g) was used. As the liquid crystal polyester, a liquid crystalline polyester polycondensed from the following raw materials (melting point 265 ° C., liquid crystal starting temperature 240 ° C.,
A melt viscosity of 23 Pa · sec) was used.

[Liquid Crystalline Polyester Raw Material 1] Copolymerization molar ratio hydroxybenzoic acid 72.5 4, 4′-dihydroxybiphenyl 7.5 ethylene glycol 20.0 terephthalic acid 27.5 Further, as the compatibilizer, p- Hydroxybenzoic acid (3
0 mol%), ethylene terephthalate (70 mol%) copolymer (melting point: 200 ° C., melt viscosity: 20 Pa · sec.) The polyethylene terephthalate, the liquid crystal polyester and the compatibilizer were dried, and the mixture was mixed with an ordinary mixture. 150 mm
Supplied to a single-screw extruder at 285 ° C, shear rate 100 sec ^-1
After being melt-mixed and weighed, the mixture was passed through a fiber-sintered stainless metal filter (10 μm cut) at a shear rate of 10 sec ⁻¹ , and then extruded into a sheet form with a draft ratio of 50 from a T-die die and heated to 25 ° C. The static cooling was applied to the maintained cooling drum to solidify it by cooling. The cast film was stretched 4 times at 110 ° C. by a longitudinal roll type stretching machine to increase the birefringence to 0.16, and then introduced into a tenter,
After stretching 4 times at 100 ℃, once cooled to 60 ℃,
After heat setting at 200 ° C., a biaxially oriented film having a thickness of 8 μm was obtained. The properties thus obtained are shown in Tables 1 and 2. From Tables 1 and 2 described above, the film of the present invention is a high quality film having a high Young's modulus and a small amount of fish eyes and oligomers, and has excellent properties as a film for various applications such as magnetic recording media and electrical insulation. You can see that

[Table 1]

[Table 2] Examples 2 and 3 A biaxially oriented film was obtained in the same manner as in Example 1, except that polyethylene terephthalate raw materials having different intrinsic viscosities were used as the non-liquid crystal polyester.

As can be seen from Tables 1 and 2, when a raw material having a high intrinsic viscosity is used, the dispersion diameter of LCP is small,
The L / D was increased, and a high-quality film having a Young's modulus larger than that of Example 1 was obtained.

Examples 4 to 7 Films were obtained in the same manner as in Example 3 except that the compatibilizer used had a different melt viscosity. As can be seen from Tables 1 and 2, the liquid crystal polyester and the compatibilizing agent have almost the same melt viscosity, which is not as high as in Example 3 in which the compatibilizing agent having a more preferable melt viscosity is used, but it is specified in the present invention. High quality films with high Young's modulus were obtained using compatibilizers with melt viscosities in the range.

Examples 8 to 11 Films were obtained in the same manner as in Example 3 except that the amount of the compatibilizer used was changed. As can be seen from Tables 1 and 2, it is preferable that the amount of the compatibilizer used is appropriate, but it is effective to use the compatibilizer in order to obtain a high quality film with a high Young's modulus. I understand.

Examples 12 and 13 Films were obtained in the same manner as in Example 3, except that the mole fraction of mesogen in the compatibilizer used was changed. As can be seen from Tables 1 and 2, it was confirmed that a film having a considerably high Young's modulus and high quality can be obtained, although it is inferior to that in Example 3 because the mole fraction of mesogen is out of the preferred range of the present invention. did it.

Comparative Examples 1 and 2 Comparative Examples 1 and 2 show the results of film formation as in Example 1 or 3 except that the compatibilizing agent was not used. As can be seen from Table 1 and Table 2, when the compatibilizer was not used, the effect of the liquid crystal polyester could not be maximized, and a high Young's modulus and high quality film could not be obtained. .

Comparative Example 3 A film was formed in the same manner as in Example 1 except that a compatibilizing agent having a higher melt viscosity than PET, which is a non-liquid crystalline polyester, was used. As can be seen from Tables 1 and 2, when a compatibilizer having a higher melt viscosity than the non-liquid crystal polyester is used, a high Young's modulus, which is the object of the present invention,
No high quality film was obtained.

[0058]

INDUSTRIAL APPLICABILITY According to the present invention, a composite comprising a non-liquid crystalline polyester, a liquid crystalline polyester and a compatibilizing agent having a specific melt viscosity and structure is used as a film, and the Young's modulus and toughness of the film are increased and the film is improved. The quality improvement has been achieved by reducing the fish eyes and oligomers of the product. For magnetic recording, electrical insulation, thermal transfer ribbon,
It can be widely used in various film application fields such as heat-sensitive stencil printing.

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display area B29L 7:00

Claims (13)

[Claims] 1. A polyester film comprising a non-liquid crystalline polyester (A), a liquid crystalline polyester (B), and a compatibilizing agent (C) having a melt viscosity lower than that of the non-liquid crystalline polyester (A). . 2. The polyester film according to claim 1, wherein the compatibilizing agent is a polyester having a mesogenic group in the main chain. 3. The content of mesogenic groups in the compatibilizer is 5
The polyester film according to claim 2, wherein the content of the polyester film is about 50 mol%. 4. The melt viscosity ratio (η _C / η _B ) of the compatibilizer (C) and the liquid crystalline polyester ( _B ) is 0.1 to 5, and any one of claims 1 to 3 is characterized in that The polyester film described in Crab. 5. The polyester film according to any one of claims 1 to 4, wherein the compatibilizing agent (C) is contained in the polyester film in an amount of 0.01 to 5% by weight. 6. The melt viscosity ratio (η _A / η _B ) of the non-liquid crystal polyester (A) and the liquid crystal polyester ( _B ) is 5 or more, according to any one of claims 1 to 5. Polyester film. 7. The liquid crystalline polyester (B) has the following (I
), (III) and (IV) structural unit liquid crystalline polyesters, (I), (II) and (IV) structural unit liquid crystalline polyesters (I), (II), (III)
) And (IV) are at least one selected from the liquid crystalline polyester consisting of the structural unit, The polyester film according to any one of claims 1 to 6. Embedded image (However, R ₁ in the formula is R ₂ represents one or more groups selected from Represents one or more groups selected from In the formula, X represents a hydrogen atom or a chlorine atom, and the structural unit [(II) + (II
I)] and the structural unit (IV) are substantially equimolar. ) 8. The polyester film according to claim 1, wherein the polyester film contains the liquid crystalline polyester (B) in an amount of 0.1 to 40% by weight. 9. The polyester film according to claim 1, wherein the non-liquid crystalline polyester (A) has an intrinsic viscosity of 0.6 or more. 10. The non-liquid crystalline polyester (A) is at least one selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate and modified products thereof, according to any one of claims 1 to 9. The polyester film described in 1. 11. The polyester film is a uniaxially or biaxially oriented film.
10. The polyester film as described in any one of 10 to 10. 12. The liquid crystalline polyester (B) is finely dispersed in a film in a fibrous form, and the L / D of the fiber is 10.
It is above, The polyester film in any one of Claims 1-11 characterized by the above-mentioned. 13. A non-liquid crystalline polyester (A), a liquid crystalline polyester (B), and a compatibilizing agent (C) having a melt viscosity lower than that of the non-liquid crystalline polyester (A) are blended to form a film. Characteristic polyester film manufacturing method.