JPH0637564B2 - Liquid crystalline film - Google Patents

Description

TECHNICAL FIELD The present invention relates to a liquid crystal film, and more specifically, the present invention is used for capacitors, food packaging, etc., for mechanical strength, surface smoothness, and size. The present invention relates to a liquid crystal film having excellent stability and thin film formability.

[Conventional technology]

Since the liquid crystal film is excellent in mechanical properties, chemical stability, dimensional stability, etc., its application to various films such as an electric insulating material, a magnetic recording tape, a photographic film, and a drawing film is being studied.

Conventionally, a liquid crystalline polyester film is manufactured by extrusion film formation using a T-die or the like. However, in this method, when the molten liquid crystalline polyester resin 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 the tear strength and the elastic modulus become extremely low in a direction (TD direction) perpendicular to the elastic modulus. Therefore, the obtained liquid crystalline polyester film is not restricted in its use. There wasn't.

Then, as a method of improving such a defect, for example, a method of biaxially stretching a polyester resin exhibiting optical anisotropy in a molten state has been proposed (JP-A-55-12342).
7 publication). However, this method has drawbacks in that it is difficult to produce a film of uniform quality, and the obtained film has insufficient tensile strength and dimensional stability.

On the other hand, the polycarbonate film produced by the solution casting method has excellent electrical characteristics and heat resistance and is used for capacitors, but it has the drawbacks of low productivity and low strength. It had the drawback of being difficult.

A composition comprising a wholly aromatic polyester resin and a polycarbonate resin is also known (JP-A-57-4055).
No. 1), the molding temperature is high, the molding stability is insufficient, and the film is brittle and poor in practical use.

In addition, incomplete aromatic polyester resin 55-90% by weight
A composition suitable for use as an optical fiber coating material comprising 10% to 45% by weight of a polycarbonate resin is known (Japanese Patent Laid-Open No. 62-59662), but this composition has a tear strength and a smooth surface for a film. It was insufficient in terms of sex.

[Problems to be solved by the invention]

It is an object of the present invention to provide a liquid crystal film having excellent mechanical strength, surface smoothness, dimensional stability and thin film formability.

[Means for solving problems]

The present inventors have conducted extensive studies in order to achieve the above object, and by forming a resin film obtained by blending a polyester resin and a polycarbonate resin having a specific structure in a specific range under specific conditions. The inventors have found that the object can be achieved, and have completed the present invention based on this finding.

That is, according to the present invention, a resin film containing 2 to 50% by weight of the following specific incomplete aromatic polyester resin (A) and 98 to 50% by weight of a polycarbonate resin is formed into a film with a draft ratio of 1.2 to 500. The present invention relates to a liquid crystal film characterized by:

The incomplete aromatic polyester resin (A) used in the present invention comprises a predetermined amount of structural unit [I], structural unit [II] and structural unit [III] represented by the following formula.

Structural unit [I] 9 to 42 mol% (in the formula, R ₁ is a hydrogen atom, a halogen atom or a carbon number 1 to
4 represents an alkyl group or an alkoxy group of 4) Structural unit [II] (In the formula, n represents an integer of 1 to 20) 9 to 42 mol% Structural unit [III] (In the formula, R ₂ has the same meaning as R ₁ above.

16 to 82 mol% Here, the incomplete polycarbonate resin means a polyester resin although not all the structural units present in the polyester have an aromatic ring. That is, the structural unit [II] does not have an aromatic ring. The structural units [I] to [III] are randomly bonded.

R ₁ of the structural unit [I] may be any of those enumerated above, but among them, a hydrogen atom, a chlorine atom, a fluorine atom, a methyl group, an ethyl group, a methoxy group, an ethoxy group, a phenoxy group and a naphthoxy group are It is suitable. N of structural unit [II]
Is an integer of 1 to 20, preferably an integer of 1 to 4. Further, R ₂ of the structural unit [III] may be any of those enumerated above as in the case of R ₁ described above, but as in R ₁ , in particular, a hydrogen atom, a chlorine atom, a fluorine atom, a methyl group, an ethyl group. , Methoxy group, ethoxy group, phenoxy group and naphthoxy group are preferred. These structural units [I], [II],
The most preferable combination of [III] is -O-CH ₂ -CH ₂ -O-, and Is.

The contents of the structural units [I], [II] and [III] are 9 to 42 mol%, 9 to 42 mol% and 16 respectively.
˜82 mol%, and the total amount is 100 mol%. Of these, the particularly important one is the structural unit [II
When the content of I] is less than 16 mol%, the aromatic polyester does not form a liquid crystal, and conversely, when it exceeds 82 mol%, a liquid crystal is formed, but moldability is deteriorated. It is not preferable. Further, this aromatic polyester is 0.5 g per 100 m of a mixed solution of phenol and tetrachloroethane (volume ratio 3: 2).
The logarithmic viscosity number measured at 30 ° C. of the solution obtained by dissolving is preferably 0.4 to 3.0, particularly preferably 0.5 to
The one of 1.5 is used. The aromatic polyester may be prepared by applying a usual method, or a commercially available product such as X7G manufactured by Eastman Kodak Company may be used.

Next, the polycarbonate resin used in the present invention has the following formula: (Here, Z is a single bond or alkylene having 1 to 8 carbons, alkylidene having 2 to 8 carbons, cycloalkylene having 5 to 15 carbons, SO ₂ , SO, O, CO or R means a hydrogen, chlorine or bromine atom or 1
~ Saturated alkyl group having 8 carbon atoms, m
Indicates a number from 0 to 4. ) Is a polymer having a structural unit represented by:

This polycarbonate resin is a solvent method, that is, a reaction between a dihydric phenol and a carbonate precursor such as phosgene in the presence of a known acid acceptor and a molecular weight modifier in a solvent such as methylene chloride, or dihydric phenol and diphenyl. It can be produced by a transesterification reaction with a carbonate precursor such as carbonate.

Here, as the dihydric phenol that can be preferably used, there are bisphenols, and 2,2-bis (4-hydroxyphenyl) propane (bisphenol A) is particularly preferable. Further, a part or all of bisphenol A may be replaced with another dihydric phenol. Examples of dihydric phenols other than bisphenol A include hydroquinone, 4,4′-dihydroxydiphenyl, bis (4-hydroxyphenyl) alkane, bis (4-hydroxyphenyl) cycloalkane, bis (4-hydroxyphenyl) sulfide, and bis. Compounds such as (4-hydroxyphenyl) sulfoxide, bis (4-hydroxyphenyl) ether or bis (3,5-dibromo-)
Mention may be made of halogenated bisphenols such as 4-hydroxyphenyl) propane, bis (3,5-dichloro-4-hydroxyphenyl) propane. These dihydric phenols may be homopolymers of dihydric phenols or copolymers or blends of two or more. Further, the polycarbonate resin used in the present invention may be a thermoplastic random branched polycarbonate obtained by reacting a polyfunctional aromatic compound with a dihydric phenol and / or a carbonate precursor.

The polycarbonate resin used in the present invention has a viscosity average molecular weight of 10, from the viewpoint of mechanical strength and moldability.
000 to 50,000 are preferable, and particularly 18,0
Those of 00 to 35,000 are preferable.

The liquid crystalline film of the present invention is obtained by forming a film of a resin film obtained by blending the essential components of the incompletely aromatic polyester resin (A) and the polycarbonate resin (B). The mixing ratio of the component (A) and the component (B) is 98 to 50% by weight with respect to the component (A) with respect to 2 to 50% by weight. When the content of the component (A) is less than 2% by weight, the tensile strength is lowered, and when it exceeds 50% by weight, the tear strength and the surface smoothness are lowered, which is not preferable. The preferable blending ratio is (B) with respect to 3 to 40% by weight of the component (A).
The component is 97-60% by weight.

In the present invention, the resin film may be mixed with various fillers and additives as desired to form a film. Examples of various fillers 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, steel. Fibers, tungsten fibers, cotton, wool, and fibers such as wool cellulose fibers, or calcium silicate, silica, clay, talc, mica, polytetrachloroethylene, graphite, aluminum trihydrate, sodium aluminum carbonate, barium ferrite, etc. To be

Among these, a preferable average particle diameter is 0.01 to 10 μm.
Examples thereof include silica, talc and clay. These fillers are added to 100 parts by weight of the film composition.
If 0.005 to 30 parts by weight is blended, slipperiness can be improved.

Furthermore, examples of various additives include antioxidants, ultraviolet absorbers, pigments, dyes, plasticizers, antistatic agents, and the like.

In order to obtain the liquid crystalline film of the present invention, a resin composition containing the above-mentioned components (A) and (B) or various fillers, additives and the like to be blended with this resin composition as desired is melted from a die. A resin film is manufactured while being extruded and taken up by a cooling roll. Here, the above-mentioned resin composition is produced by mixing the respective components after drying and melt-kneading. In this kneading step, a dry blending method, a fusion blending method, a multi-stage melt blending method, a simple melt blending method or the like can be applied, and if necessary, a single-screw extruder, a twin-screw extruder, a co-kneader, a Banbury mixer, A Henschel mixer or the like can be used.

Then, this resin film is formed into a film with a specific draft ratio to obtain a target liquid crystalline film.

A method for manufacturing a liquid crystal film will be described with reference to the accompanying drawings. The figure is a schematic view for explaining one example of the production method (when an air knife is used), and the resin composition is T
From the die 1, melting temperature 220-350 ° C, preferably 2
It is melt extruded in the range of 30 to 320 ° C. If this temperature is less than 220 ° C., the melt viscosity is high and the orientation is difficult to proceed,
On the other hand, when the temperature exceeds 350 ° C., the resin is easily decomposed, and the orientation is hard to proceed. Regarding the position of the T-die, the height of the lip 3 (the length of the molten resin dripped) is 1 to 100 mm,
It is particularly preferably in the range of 1 to 60 mm. If this height exceeds 100 mm, neck-in becomes remarkable, and orientation becomes difficult. The opening degree of the lip 3 is preferably 0.05 to 5 mm, particularly 0.1 to 3 mm. If the opening exceeds 5 mm, the orientation is difficult to proceed, which is not preferable.

The molten film 4 thus extruded from the T die 1
Is blown by an air knife 5 at high speed with a thin linear width, is pressed against the cooling roll 2, is cooled, and is taken up. The air knife has a role of improving the contact between the molten film 4 and the cooling roll 2, enhancing the cooling effect, and improving the orientation of the film. The position of the air knife and cooling conditions are appropriately selected depending on factors such as physical properties of the film, thickness, take-up speed, and T-die position. Air knife lip 6 is chill roll 2 to 1
It is preferably located at a distance of -100 mm, especially 5-50 mm. If this distance is less than 1 mm, uniform control is difficult, and if it exceeds 100 mm, the effect is not fully exhibited. On the other hand, the opening of the lip 6 is 0.01-3 mm, especially 0.1-2 m
It is preferably in the range of m. The air velocity is preferably 0.5 to 70 m / sec, more preferably 5 to 60 m / sec.
It is selected in the range of m / sec. If the flow velocity is less than 0.5 m / sec, the effect is small, and if it exceeds 70 m / sec, stable molding becomes difficult. The air pressure is preferably in the range of 15-60 mmHg. Further, this air flow is preferably blown horizontally or 10 ° downward toward the contact line between the molten film and the cooling roll or slightly downstream thereof.

On the other hand, the temperature of the cooling roll 2 is 10 to 160 ° C., especially 20.
Is preferably in the range of from 150 to 150 ° C., and in order to obtain the liquid crystal film of the present invention, the draft ratio, that is, the ratio of the extrusion rate of the molten resin / the take-up rate of the film is 1.2-5.
It must be 00. If the draft ratio is less than 1.2, the orientation is difficult to proceed, and if it exceeds 500, stable molding is difficult, which is not preferable. The preferred range of draft ratio is 1.
5 to 300.

Although the example of pressing the molten film against the cooling roll by air pressure using the air knife has been described above, an electrostatic pressing method may be used instead of such an air pressure pressing method. The electrostatic pressing method includes an electrostatic tip probe method and an electrostatic wire pressing method, and the electrostatic wire pressing method is preferable. In the electrostatic wire pressing method, a stainless wire is stretched in parallel with a roll at a position 1 to 10 mm away from a cooling roll,
A method of applying a DC voltage of about 1 to 5 KV is usually used. This electrostatic pressing method can be used in combination with the pneumatic pressing method described above.

Further, an air chamber (a device for blowing a wide air flow) may be provided below the air knife or the like to improve the pressing and cooling effects of the film.

In this manner, a high-quality and highly-oriented film with less neck-in and uniform thickness can be obtained. If desired, this film can be stretched by a conventionally used stretching method, for example, a tenter method or a tubular multi-stage stretching method. Method, etc., may be uniaxially stretched in the machine axis direction (MD direction) or in the direction perpendicular to the machine axis (TD direction), or may be biaxially stretched in the machine axis direction and the direction perpendicular to the machine axis. . The stretching temperature is usually 50 to 250 ° C, preferably 70 to 130 ° C. Regarding the draw ratio, uniaxial stretching (TD
Direction or MD direction) is usually 1.5 to 8 times, and in the case of biaxial stretching (TD direction and MD direction) is usually 1.2.
It is selected in the range of up to 6 times. In this way, the stretched film can be heat-treated as necessary. This heat treatment is carried out by heating the stretched film as it is, or by heating it at a temperature in the range of 150 to 300 ° C. for about 1 second to 10 minutes while subjecting it to limited shrinkage or stretching. This heat treatment improves the crystallinity of the film and makes it more excellent in heat resistance and dimensional stability.

Furthermore, two or more films obtained by the method of the present invention can be joined together and used as a laminate. In this case, the extrusion direction of at least two sheets is 30 ° with each other.
It is preferable to laminate so as to intersect with each other. As a lamination method, a conventionally used method, for example, a method using heat, a method using ultrasonic waves, a method using corona discharge,
A method using an adhesive or the like can be used.

Since the film of the present invention has excellent mechanical strength, it can be made thinner when the strength is the same as the conventional product. Further, since it has excellent electric characteristics, it is preferably used as a film for capacitors.

That is, the size of the capacitor is proportional to the square of the film thickness of the dielectric material and inversely proportional to the dielectric constant of the dielectric material. Therefore, when the film of the present invention is used, it is much smaller than the other capacitors even with the same capacitance.

Further, the film of the present invention has excellent mechanical strength, gas barrier properties, and transparency, and is therefore suitable as a film for food packaging.

Furthermore, since the film of the present invention is excellent in dimensional stability and surface smoothness, it can be used for magnetic tapes, printed circuit boards,
It is also suitable as an insulating film, an optical film, an acoustic vibration film, a drawing film, and a polarizing film.

〔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.

Example 1 10 parts by weight of a polyester resin (PHB 60), 90 parts by weight of a polycarbonate resin (A 2200), and 0.1 parts by weight of silica having an average particle size of 0.5 μ were dried and then pelletized using a twin-screw extruder.

Then, the obtained pellets were fed to a 30 mmφ uniaxial extruder and extruded from a T die having a width of 20 mm under the conditions of a die temperature of 280 ° C., a lip opening of 1 mm and an air gap of 20 mm,
Then take this with a cast roll (draft ratio 2.
5), a film having a thickness of 400 μ was obtained.

The test results of the obtained film are shown in Table 1.

Examples 2 to 14 and Comparative Examples 1 to 5 The same procedure as in Example 1 was carried out except for the conditions shown in Table 1.

As the polyester resin and the polycarbonate resin as the component (A), the following ones were used, and the test method was as follows.

(A) Polyester resin PHB60: Structural unit [I] 40 mol% Logarithmic viscosity number 1.0 [II] 40 mol% [III] 60 mol% PHB80: Structural unit [I] 20 mol% [II] 20 mol% [III] 80 mol% However, [I] [II] -O-CH ₂ -CH ₂ -O- [III] (B) Polycarbonate resin A2200: manufactured by Idemitsu Petrochemical Co., Ltd., trade name "Taflon A2200" viscosity average molecular weight 20,500 A3000: manufactured by Idemitsu Petrochemical Co., Ltd., trade name "Taflon A3000" viscosity average molecular weight 28,000 * 1: 4-oxybenzoyl unit 40 mol%, 1,2
-Ethylenedioxy-4,4'-dibenzoyl unit 1
5 mol%, terephthaloyl unit 15 mol%, methyl-substituted 1,4-dioxyphenylene unit 30 mol%, viscosity average molecular weight 28,000 Film thickness unevenness: uneven thickness within 10 m Surface smoothness: center line average Roughness Tensile elastic modulus, tensile breaking strength: conforming to JIS-K-2318 Elemendorff tear strength: conforming to JIS-K-1702 Linear expansion coefficient: -100 to 100 by using a thermal analysis device manufactured by Seiko Denshi KK Measured at a temperature in the range of 100 ° C, 0-5
The value in the temperature range of 0 ° C. was adopted.

The sample length was 20 mm × 5 mm, the heating rate was 4 ° C./min, and the load was 1 g.

Volume resistivity: JIS-C-2318 compliant Dielectric constant, Inductive loss: Yokogawa Hewlett-Packard Co.,
Using LF impedance analyzer, room temperature 23 ℃,
Uses a film with a humidity of 50% and a thickness of 6μ Oxygen permeability: 2
Measured at 3 ℃ and 0% RH, converted to 25μ [Effects of the Invention] The liquid crystalline film obtained by the present invention has mechanical strength,
It has excellent surface smoothness and dimensional stability, can be easily thinned, and has excellent gas barrier properties and electrical characteristics, and is suitable for various applications.

[Brief description of drawings]

FIG. 1 is a schematic diagram for explaining an example of a method for producing a film of the present invention, in which reference numeral 1 is a T die, 2 is a cooling roll, 3 is a lip of the T die, 4 is a molten film. ,
Reference numeral 5 is an air knife, and 6 is a lip of the air knife.

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display area B29L 7:00 4F

Claims (4)

[Claims] 1. The following incomplete aromatic polyester resin (A)
2-50% by weight and polycarbonate resin 98-50
Draft ratio of 1.2-
A liquid crystal film characterized by being formed into a film with 500. (A) Incomplete aromatic polyester resin structural unit [I] comprising a predetermined amount of structural unit [I], structural unit [II] and structural unit [III] represented by the following formula 9 to 42 mol% (in the formula, R ₁ is a hydrogen atom, a halogen atom or a carbon number 1 to
4 represents an alkyl group or an alkoxy group of 4) Structural unit [II] 9 to 42 mol% (in the formula, n represents an integer of 1 to 20) Structural unit [III] (In the formula, R ₂ represents the same meaning as the above R _1. ) 16 to 82 mol% 2. The liquid crystal film according to claim 1, wherein the liquid crystal film is a liquid crystal film for capacitors. 3. The liquid crystalline film according to claim 1, wherein the liquid crystalline film is a liquid crystalline film for food packaging. 4. The liquid crystal film according to claim 1, wherein the liquid crystal film is a liquid crystal film for acoustic vibration.