JPH082974B2 - High strength and high elasticity polyester film - Google Patents

Description

TECHNICAL FIELD The present invention relates to a film made of a polyester (hereinafter referred to as a liquid crystal polyester) capable of forming an anisotropic melt, and more specifically, a film made of a liquid crystal polyester. The present invention relates to a high-strength, high-elasticity polyester film having high tensile strength and elastic modulus in both the vertical and horizontal directions.

(Prior Art) In recent years, films made from various polymers have become indispensable for daily life. For example, various films such as a high strength film, a high elasticity film, an oxygen barrier film, a transparent film, a conductive film, a heat resistant film, and a light barrier film have been developed and used for various purposes. In particular, films with high strength and elasticity have entered our lives not only in the fields of machinery and electronics, but also for industrial and consumer use.

Conventionally, a polyethylene terephthalate (hereinafter referred to as PET) stretched film has been used in this field.
The tensile strength is 22 to 24 kg / mm ² and the elastic modulus is about 350 kg / mm ² , and it has been desired to further increase the strength and elasticity.

On the other hand, liquid crystal polymers, especially liquid crystal polyesters, are attracting attention as film materials because highly oriented molded products can be obtained simply by extrusion molding. In particular, the liquid crystal polyester obtained by copolymerizing para-hydroxybenzoic acid (hereinafter abbreviated as PHB) and PET has already been mass-produced, and it is expected to be applied to a film as a mass-produced liquid-crystal polyester. However, when the film is formed by the roll take-up method, it is not stretched and PE
Although it has a tensile strength that exceeds T, it has a drawback that it can easily tear in the longitudinal direction because the tensile strength in the lateral direction is less than several kg / mm ² , and it has the drawback of easily tearing in the longitudinal direction. Was scarce.

Several proposals have been made for producing a liquid crystal polyester film having so-called little anisotropy, which has a practical tensile strength in the lateral direction. For example, Japanese Patent Publication No. 59-26471 discloses that two or more liquid crystal polyesters having strong anisotropy are stuck together to eliminate the anisotropy. Further, in Japanese Patent Laid-Open No. 61-102234, the stretching ratio in the direction perpendicular to the take-up direction is 2.
It has been proposed to produce a liquid crystal polyester film with less anisotropy by making it 5 times or more.

(Problems to be Solved by the Invention) However, there is no specific example of the liquid crystal polyester used in the present invention in any of the above publications, and the elastic modulus of the film is superior to that of the stretched PET film. Although some cases have been reported,
Films with a tensile strength of 25 kg / mm ² or more have not been reported.

An object of the present invention is to provide a high-strength and high-elasticity polyester film having a tensile strength and an elastic modulus higher than those of a stretched PET film in both the vertical and horizontal directions.

(Means for Solving the Problems) As a result of intensive studies to achieve the above-mentioned object, the present inventor has found that a specific PHB /
The inventors have found that the above object can be achieved by processing a PET-copolymerized liquid crystal polyester under specific conditions, and have reached the present invention.

That is, the present invention is a film comprising a polyester capable of forming an anisotropic melt, wherein the polyester is
Copolymerized polyester consisting of 30 to 74 mol% of PHB residues, 35 to 13 mol% of terephthalic acid residues, and 35 to 13 mol% of ethylene glycol residues (provided that terephthalic acid residues and ethylene glycol residues are The molar ratio is 1),
The film has at least 25 in both vertical and horizontal directions.
The high strength and high elastic polyester film characterized by having a tensile strength of at least an elastic modulus of 400 kg / mm ² in kg / mm ² in which the gist.

The film of the present invention comprises a liquid crystal polyester composed of a copolyester modified with PHB, in particular PHB residues 30 to 7
Copolymerized polyester consisting of 4 mol%, residues of terephthalic acid 35 to 13 mol% and residues of ethylene glycol 35 to 13 mol% (where the molar ratio of terephthalic acid residues to ethylene glycol residues is 1) ) Made of liquid crystal polyester.

If the proportion of the PHB component in the liquid crystal polyester is too low or too high, it will not be possible to form a highly anisotropic melt necessary for obtaining a high-strength and high-elasticity film.
It is 4 mol%, preferably 36 to 70 mol%. From the viewpoint of moldability, it is preferably less than 60%, and from the viewpoint of heat resistance, it is preferably 60% or more. The liquid crystalline polyester in the present invention is, for example, an aliphatic glycol having 3 or more carbon atoms such as propylene glycol, butanediol, hexanediol, diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol within the range not impairing the object of the present invention. , Polyols such as tripropylene glycol and polypropylene glycol, alicyclic diols such as cyclohexanediol and cyclohexanedimethanol and their derivatives, malonic acid, succinic acid, suberic acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, Aliphatic dicarboxylic acids having 20 or less carbon atoms such as tetradecanedioic acid and eicosanedioic acid, long-chain aliphatic dicarboxylic acids such as dimer acid, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, Aromatic dicarboxylic acids such as thallic acid, isophthalic acid, 2.6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1.5-naphthalenedicarboxylic acid and their derivatives may be copolymerized, and It does not matter even if it contains additives such as flame retardants, stabilizers and pigments.

The liquid crystal polyester according to the present invention comprises phenol, 1,
It is necessary that the intrinsic viscosity measured at 35 ° C. using a mixed solvent in which the weight ratio of 1,2,2-tetrachloroethane is 1: 1 is 0.6 or more, preferably 0.7 or more. When the intrinsic viscosity is less than 0.6, the molecular weight is too low, and therefore the film intended by the present invention cannot be obtained no matter how the processing conditions are modified. Regarding the measurement of intrinsic viscosity Polyesters with a PHB component ratio of less than 60 mol% are easily dissolved in the above mixed solvent, but in the case of a polyester with a PHB component ratio of more than 60 mol%, the sample is pulverized and mixed with the above mixed solvent. 145 ~ 160 ℃ in
It is preferable to dissolve by stirring for about 20 minutes.

The method for preparing such a liquid crystal polyester is not particularly limited. For example, PET is mixed with acetoxybenzoic acid, and then the mixture is heated and melted to perform an acidolysis reaction. Various conventionally known methods such as the method described in JP-A-18016 can be appropriately adopted. At this time, in order to obtain a polyester having a high degree of polymerization, it is a preferable method to use a highly pure raw material and sufficiently manage it so as not to mix water. further,
During the reaction, if an extremely high PHB blocking property is generated, it will be precipitated as insoluble and infusible particulate foreign matter, which not only extremely deteriorates the stretchability of the film but also roughens the film surface. Since it loses commercial value, particulate foreign matter is likely to occur
When PHB is more than 60% mol%, it is desirable to polymerize as randomly as possible.

The film of the present invention can be produced by melt-extruding the above liquid crystal polyester to form a film, and then stretching the film at a specific temperature. As a film forming device,
A conventionally known melt extrusion film forming apparatus for polyester can be used. It is also possible to apply the electrostatic contact method to quench the film during film formation. PHB is 6
When it is less than 0 mol%, it is preferable to extrude at 240 to 300 ° C, particularly 250 to 290 ° C. The PHB molar ratio (x) is 60.
When it is at least mol%, the extrusion temperature (T ₂ ) is preferably in the range represented by the following formula.

3 (x-60) +220 < T 2 <3 (x-60) +290 or stretching method is not limited particularly, the liquid crystal polyester in the present invention has a low melt viscosity, preferably stretching by the inflation method.

When the PHB molar ratio is less than 60 mol%, the stretching temperature is from 140 to
185 ° C, especially 150-170 ° C is preferred. On the other hand, when the molar ratio (x) of PHB is 60 mol% or more, the stretching temperature (T ₁ ) is preferably in the range represented by the following formula.

10 (x-60) +180 < T 1 <10 (x-60) +140 temperature control method is not limited particularly, the glass substrate was immersed in cooled once medium extruded tubular article, a method of re-machining is preferred.

The draw ratio is the product of the draw ratio in the vertical and horizontal directions is 1
It should be 0, preferably 20 and particularly preferably more than 30. At this time, since it is already oriented to some extent in the vertical direction due to shearing and pulling applied during extrusion, it is necessary to stretch more in the horizontal direction than in the vertical direction. In order to obtain a film having substantially the same physical properties such as tensile strength and elastic modulus in the longitudinal direction and the transverse direction, the stretching ratio in the longitudinal direction and the transverse direction is usually 5 to 40, particularly preferably 5 to 20.

(Example) Hereinafter, the present invention will be described in more detail with reference to examples.

The intrinsic viscosity of the polyester in the examples is phenol /
It is measured at 35 ° C. in a mixed solvent of tetrachloroethane = 1/1 (weight ratio). The liquid crystallinity of polyester was judged by observing it at 280 ° C under crossed Nicols using a polarizing microscope. The tensile strength and tensile modulus of the film are 5m using a tensile tester (Autograph made by Shimadzu Corporation).
It was measured at m / min at 25 ° C.

Reference Example 1 PHB residue 42.8 mol%, terephthalic acid residue 28.6 mol%, ethylene glycol residue 28.6 mol% Highly viscous copolymer liquid crystal polyester (PHB / PET)
It is 0/40. However, the minimum repeating unit of PET, ethylene terephthalate, is regarded as 1 mol. ) Was produced as follows.

A PET chip with an intrinsic viscosity of 0.71 and powder of paraacetoxybenzoic acid were charged in a reactor at a molar ratio of 40/60, and the raw material was sufficiently dried under reduced pressure in the reactor, and then a small amount of nitrogen gas was flowed. After the temperature was raised to ℃, all the raw materials were melted and kept at that temperature for 40 minutes to allow acetic acid to flow out and to perform the acidolysis reaction. Then, in 90 minutes, full vacuum (1tor
Depressurization is started according to the depressurization schedule such that r), then the temperature is raised sequentially, and finally at a temperature of 280 ° C, 0.3
A polycondensation reaction was performed in the melt phase for 8 hours under a reduced pressure of torr, and then chips were formed by a conventional method.

The resulting polyester has liquid crystallinity and an intrinsic viscosity of 0.
It was 72.

Reference example 2 PHB residue 66.6 mol%, terephthalic acid residue 16.7 mol%, ethylene glycol residue 16.7 mol% Highly viscous liquid crystal polyester (PHB / PET copolymerization ratio is 80 /
Twenty. ) Was produced as follows.

First, as the first step, the PHB / PET copolymerization ratio was 6 in the same manner as in Reference Example 1 except that the reaction time of the polycondensation reaction in the melt phase under a reduced pressure of 0.3 torr was shortened from 8 hours to 3 hours.
At 0/40, we prepared a copolymerized mixed crystal polyester with an intrinsic viscosity of 0.61.

Next, in the second step, 30 kg of the dry polymer chips obtained in the first step and the target PET: PHB molar ratio of 20/8
After charging 36.3 kg of paraacetoxybenzoic acid, which is insufficient to prepare a polyester of 0, to the reactor, 2
The temperature was raised to 80 ℃ and the acidolysis reaction was performed for 40 minutes. After that, the temperature was raised sequentially, and finally the polycondensation reaction was carried out in the molten phase at a temperature of 300 ° C under a reduced pressure of 0.3 torr for 3 hours. As a result, the intrinsic viscosity was 0.70, the melting temperature was 278 ° C, and the glass transition point was At 79 ° C., a liquid crystalline polyester containing no foreign matter was obtained.

Reference Example 3 A PHB / PET copolymerization ratio was 60/40 in the same manner as in Reference Example 1 except that the reaction time of the polycondensation reaction in the melt phase under a reduced pressure of 0.3 torr was shortened from 8 hours to 6 hours. Intrinsic viscosity is 0.
A co-polymerized liquid crystalline polyester that is 68 was produced.

Examples 1 to 4 The liquid crystalline polyesters obtained in Reference Example 1 were extruded at a resin temperature of 260 ° C. from a 40 mm diameter extruder equipped with a die having ring-shaped holes, and quenched with water while applying a 1.2-fold draw ratio. By doing so, a pipe having an outer diameter of 15 mm and a wall thickness of 1.5 mm was obtained.

This pipe was cut into a length of 80 cm and heated in an oven to 156 ° C (Example 1), 160 ° C (Example 2), 165 ° C (Example 3) or 170 ° C (Example 4), respectively. Then, it was taken out of the oven and inflation-stretched at room temperature (25 ° C) under a pressure of 200 mmHg. At that time, by adjusting the distance between both ends of the pipe, in the case of Example 1, 1.8 times in the MD direction and 15 times in the TD direction, and in Example 2, 2.1 times in the MD direction and TD direction. In the case of Example 3
Stretching was performed 2.3 times in the MD direction and 32 times in the TD direction, and in Example 4, 2.5 times in the MD direction and 37 times in the TD direction.
Here, the MD direction means the extruding direction of the pipe, and the TD direction means the perpendicular direction.

The tensile strength and elastic modulus of the obtained films of Examples 1 to 4 are shown in Table 1.

As is clear from Table 1, the film of the present invention has a tensile strength exceeding 25 kg / mm ² in both MD and TD directions and 1000 kg / mm ²
It is a high-strength, high-elasticity film with an elastic modulus that greatly exceeds that of the commercially available PET film, and has significantly better performance than commercially available PET films.

Examples 5 and 6 Extrusion temperature of resin from the extruder was changed from 260 ° C to 2
A pipe having the same outer diameter and wall thickness as in Example 1 was obtained in the same manner as in Example 1 except that the temperature was changed to 50 ° C (Example 5) or 270 ° C (Example 6). This pipe was cut into a length of 80 cm, heated to 165 ° C. in an oven, taken out of the oven, and subjected to inflation drawing in the same manner as in Example 1. In Example 5, 2.3 times in the MD direction, Stretching 12 times in the TD direction, 2.0 times in the MD direction and 27 in the TD direction in the case of Example 6.
A film stretched twice was obtained.

The tensile strength and elastic modulus of the obtained films of Examples 1 to 4 are shown in Table 1.

As is clear from Table 1, the film of the present invention has remarkably excellent performance as compared with the commercially available PET film.

Example 7 Example 1 except that the width of the ring-shaped hole was changed to a narrow one.
In the same manner as above, a pipe with an outer diameter of 15 mm and a wall thickness of 0.7 mm was obtained. This pipe was cut into a length of 80 cm, heated in an oven to 155 ° C., taken out of the oven, and subjected to inflation drawing in the same manner as in Example 1, with a MD ratio of 1.8 times and a TD direction of 20 times. A film stretched twice was obtained.

The tensile strength and elastic modulus of the obtained Example 7 film are shown in Table 1.

As is clear from Table 1, the film of the present invention has remarkably excellent performance as compared with the commercially available PET film.

Example 8 The liquid crystal polyester of Reference Example 3 was extruded in the same manner as in Example 7 to obtain a pipe having an outer diameter of 15 mm and a wall thickness of 0.7 mm. This pipe was cut to a length of 80 cm, heated to 150 ° C in the oven, then removed from the oven, and the pressure applied was 200 mmHg.
In the same manner as in Example 1 except that the film was changed to 180 mmHg, the film was stretched 1.6 times in the MD direction and 16 times in the TD direction to obtain a film.

The tensile strength and elastic modulus of the obtained Example 8 film are shown in Table 1.

As is clear from Table 1, the film of the present invention has remarkably excellent performance as compared with the commercially available PET film.

Example 9 The liquid crystal polyester obtained in Reference Example 2 was extruded from a 40 mm diameter extruder equipped with a die having ring-shaped holes at a resin temperature of 305 ° C. and rapidly cooled with water while applying a 1.3-fold draw ratio. A pipe with an outer diameter of 15 mm and a wall thickness of 1.4 mm was obtained by.

This pipe is cut to a length of 80 cm and placed in an oven at 265 ° C.
After heating to room temperature, remove from the oven, and at room temperature (25 ℃)
Inflation stretching was carried out at a pressure of 200 mmHg to obtain a film stretched 1.5 times in MD and 19 times in TD.

The tensile strength and elastic modulus of the resulting film of Example 9 are shown in Table 1.

As is clear from Table 1, the film of the present invention is the MD direction, TD direction with 35 kg / mm greater than ² tensile strength and 2000 kg / mm ²
It is a high-strength, high-elasticity film with an elastic modulus that greatly exceeds that of the commercially available PET film, and has significantly better performance than commercially available PET films.

(Effects of the Invention) The polyester film of the present invention has a high tensile strength and elastic modulus in both the vertical and horizontal directions.
With good mechanical performance not found in PET film,
Moreover, it has excellent dimensional stability. Taking advantage of these characteristics, the polyester film of the present invention can be used not only for magnetic recording materials such as audio tapes, video tapes, floppy disks, base films for thermal transfer recording media, industrial materials such as printing, and barrier properties. It also has a wide range of uses such as packaging and packaging.
In addition, it can be expected to expand to a wider range of applications by using a multilayer laminate with existing films.

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area C08L 67:00

Claims (1)

[Claims] 1. A film comprising a polyester capable of forming an anisotropic melt, the polyester comprising 30-74 mol% residues of p-hydroxybenzoic acid and terephthalic acid residues.
35 to 13 mol% and ethylene glycol residues 35 to 13 mol%
Made of a copolyester consisting of terephthalic acid residues and ethylene glycol residues in a molar ratio of 1, and the film has a tensile strength of at least 25 kg / mm ^{2 in} both the vertical and horizontal directions and at least 400 kg / A high-strength, high-elasticity polyester film having an elastic modulus of mm ² .