JP2000290512A - Polymer alloy and its film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve edge splitting strength by combining a thermoplastic polymer and an amorphous polymer which can form an optically isomeric fused phase by a specified rate without damaging superior characteristics of the thermoplastic polymer. SOLUTION: A polymer alloy is composed of 97.1-99.0 wt.% of a thermoplastic polymer and 1.0-2.9 wt.% (based on the total amount of the polymers) of an amorphous polymer which can form an optically isomeric fused phase. A thermoplastic liquid crystal polymer is preferably a copolymer composed of a p-hydroxy benzoic acid structure unit and a 6-hydroxy-2-naphthoic acid structure unit, most preferably the copolymer containing the former of 60-90 mole %. The amorphous polymer includes, for example, α polysulfone, a polyether sulfone, a polyarylate and the like, and most preferably is a polyarylate composed of an aromatic discarboxylic acid unit and a diphenol unit in terms of stability as a polymer alloy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polymer alloy using a thermoplastic polymer capable of forming an optically anisotropic molten phase (hereinafter referred to as a thermoplastic liquid crystal polymer). In addition, the present invention relates to a film made of a polymer alloy having improved edge tear strength, which is important for the passability of a processing step. Since such a film has excellent processability without impairing the excellent properties of a film made of a thermoplastic liquid crystal polymer (hereinafter, referred to as a thermoplastic liquid crystal polymer film), it can be used as an electric insulating material or an electric circuit board. Useful as plate material. Here, the edge crack strength refers to the strength against breakage or breakage occurring at the edge of a film or the like.

[0002]

2. Description of the Related Art Thermoplastic liquid crystal polymers must (1) be directly heat-bondable to metal, (2) be heat-resistant, (3) have low moisture absorption, and (4) have excellent thermal dimensional stability. ,(Five)
Excellent dimensional stability in humidity, (6) excellent in high frequency characteristics, (7) flame retardant even without containing flame retardants such as toxic halogen, phosphorus, antimony, etc., (8) radiation resistance (9) The coefficient of thermal expansion can be controlled, (10)
It is considered to be one of ideal materials such as an electrical insulating material, a heat-resistant material, a circuit board material, and a gas barrier material because of its features such as flexibility at low temperatures. And there has been a strong demand for the practical use of the film or sheet.

[0003] By the way, the viewpoint of the research and development of the conventional thermoplastic liquid crystal polymer has focused particularly on good tensile resistance in the flow direction and excellent flowability. For example, a very thin fiber having excellent tensile resistance is produced from a thermoplastic liquid crystal polymer by melt spinning, and a woven or knitted fabric is produced and used from this fiber. Such properties are due to the anisotropy of the thermoplastic liquid crystal polymer, but when applied to planar films, this anisotropy is often a fatal drawback. The biggest drawback is that the liquid crystal polymer film is easily torn (breakable) in the direction of discharge from the forming die, which has hindered the practical use of the planar film.

[0004] In recent years, there have been proposed various methods for producing practical films which break the anisotropy of the thermoplastic liquid crystal polymer and eliminate the drawback of easily tearing in one direction. The method is
(a) Improvement of a film forming apparatus and / or a film forming method, and (b) Modification of a thermoplastic liquid crystal polymer as a raw material resin with an additive.

[0005] As a method of improving the film forming apparatus and / or the film forming method, (1) a so-called rotary die in which a molten liquid crystal polymer is discharged by using movable die lips rotating in opposite directions through an annular slit is used. Inflation film forming method (Tokuheihei 3-504948, Tokuhyohei 4)
506779), (2) a film forming method of intersecting the ejection direction of each layer of a multilayer T-die (Japanese Patent Application Laid-Open No. 2-89617, Japanese Patent Application Laid-Open No. 63-264323), and (3) a magnetic field in the lateral direction using a T-die. Film forming method (Japanese Patent Laid-Open No. 63-242513)
No.), (4) laminating an anisotropic liquid crystal polymer film obtained using a T-die or the like with a synthetic resin film,
A post-processing method called a laminate stretching method in which the laminate is laterally stretched (stretched in the TD direction at a stretching ratio larger than the MD direction) (JP-A-7-323506, JP-A-7-25
No. 1438, JP-A-9-131789), (5) Inflation film forming method using a stationary annular die (JP-A-Heisei 2
-3430 and JP-A-2-88212).

The above (1), (2), and (3) are directed to aligning liquid crystal polymer molecules in a molten state discharged from a die having an annular or linear slit in two directions inside the die. This is a method for preventing the liquid crystal polymer molecules of the obtained film from being oriented in one direction. The method (4) is a method of reorienting a film in which liquid crystal polymer molecules are oriented in one direction obtained by discharging from a die by post-processing, thereby breaking the unidirectional molecular orientation. The method (5) is a method of breaking the unidirectional molecular orientation in a non-solidified (semi-molten) film in which liquid crystal polymer molecules are oriented in one direction obtained by discharging from a die.

On the other hand, the method of modifying the thermoplastic liquid crystal polymer as a raw material resin with an additive can be exemplified by a number of methods including the method of adding an inorganic substance. An alloy method is disclosed in U.S. Pat.
No. 49338. In particular, JP-A-6-49
No. 338 discloses a polymer alloy comprising 45 to 97% by weight of a liquid crystal aromatic polyester and 3 to 55% by weight (based on the total amount of polyester) of an amorphous polyarylester. The essence is that by diluting with a large amount of added amorphous polyarylester, the expression of anisotropy of the liquid crystal aromatic polyester is suppressed, and as the amount of amorphous polyarylester added increases, Although the anisotropy is improved, not only the mechanical properties (eg, tensile modulus, bending stress and flexural modulus), which are excellent properties of the liquid crystal aromatic polyester, are weakened, but also the relevance to the object of the present invention is reduced. It is reported in Example 1 that a decrease in tear strength, which seems to be caused, occurs.

[0008] These techniques for breaking the anisotropy of the thermoplastic liquid crystal polymer can eliminate the disadvantage that the thermoplastic liquid crystal polymer film or sheet is easily ruptured in a specific direction (easiness of cracking), but the absolute strength ( In fact, improvement in end crack strength) has not been achieved.

[0009]

The improvement of the edge crack strength not only improves the properties of the processed product using the thermoplastic liquid crystal polymer, but also improves the passability of the processing step. Has significant significance. To illustrate the problems in the process that occurs when the end crack strength is low, the chip is likely to cause chipping or tearing in the width direction end of the film, and the tension applied when the thermoplastic liquid crystal polymer film is processed by Roll To Roll, The film breaks from such a defect or tear as a starting point. There are serious problems such as breaking of the film without being able to withstand the rotational strain stress applied to the film when screwing the opening.

[0010] An object of the present invention is to provide a polymer alloy capable of improving the edge crack strength without impairing the excellent properties of the thermoplastic liquid crystal polymer.

[0011]

Means for Solving the Problems In order to improve the edge tear strength of the thermoplastic liquid crystal polymer, the present inventors have conducted more detailed experiments, observations and considerations. It has been found that a polymer alloy comprising 97.1 to 99.0% by weight and 1.0 to 2.9% by weight (based on the total amount of the polymer) of an amorphous polymer achieves the object. Was. The present invention is based on the surprising finding that the blending ratio of the amorphous polymer is much lower than expected by the research and development personnel engaged in the field.

According to the present invention, the thermoplastic liquid crystal polymer 9
The amorphous polymer is added in an amount of 1.0 to 9 to 99.0% by weight.
By adding 2.9% by weight, the end crack strength is improved to 2.5 times or more as compared with the case where no amorphous polymer is added without impairing the excellent properties of the thermoplastic liquid crystal polymer film. be able to.

The raw material of the thermoplastic liquid crystal polymer used in the present invention is not particularly limited, and specific examples thereof include compounds (a) to (d) and derivatives thereof shown below. There may be mentioned known thermotropic liquid crystal polyesters and thermotropic liquid crystal polyesteramides. However, in order to obtain a polymer capable of forming an optically anisotropic molten phase,
It goes without saying that there is an appropriate range for each combination of the starting compounds.

In particular, it is a copolymer comprising a p-hydroxybenzoic acid structural unit and a 6-hydroxy-2-naphthoic acid structural unit, wherein the p-hydroxybenzoic acid structural unit is 6
A copolymer synthesized so as to be 0 to 90 mol% is exemplified as a thermoplastic liquid crystal polymer in which the effects of the present invention are particularly exhibited.

(A) Aromatic or aliphatic dihydroxy compounds (see Table 1 for typical examples)

[0016]

[Table 1]

(B) Aromatic or aliphatic dicarboxylic acids (for typical examples, see Table 2)

[0018]

[Table 2]

(C) Aromatic hydroxycarboxylic acids (see Table 3 for typical examples)

[0020]

[Table 3]

(D) Aromatic diamine, aromatic hydroxyamine or aromatic aminocarboxylic acid (for typical examples, see Table 4)

[0022]

[Table 4]

Representative examples of thermoplastic liquid crystal polymers obtained from these starting compounds include copolymers (a) to (e) having the structural units shown in Table 5.

[0024]

[Table 5]

The thermoplastic liquid crystal polymer used in the present invention may have a temperature in the range of about 200 to about 400 ° C., particularly about 250 to about 350 ° C. for the purpose of obtaining the desired heat resistance and processability of the film. Are preferred, but from the viewpoint of film production, those having a relatively low melting point are preferred. Therefore, when a higher heat resistance and a higher melting point are required, it is advantageous to heat the obtained film to a desired heat resistance and a higher melting point. To explain an example of the condition of the heat treatment, even if the melting point of the obtained film is 283 ° C., if the film is heated at 260 ° C. for 5 hours, the melting point becomes 320 ° C.
become.

Examples of the non-crystalline polymer used in the present invention include non-crystalline polymers such as polysulfone, polyether sulfone, polyphenylene sulfide, polycarbonate, polyethylene isophthalate and polyarylate.

In particular, the blend with the thermoplastic liquid crystal polymer used in the present invention is uniform, and the stability as a so-called polymer alloy (characteristics such as dispersion uniformity in extrusion molding and long-term thermal stability) is obtained. An amorphous polyarylate comprising an aromatic dicarboxylic acid unit and a diphenol unit is preferred. Further, for the purpose of adjusting the melting point close to the thermoplastic liquid crystal polymer to be used, isophthalic acid or terephthalic acid or a mixture of isophthalic acid and terephthalic acid as an aromatic dicarboxylic acid constituting the amorphous polyarylate. Preferably, it is used.

As the diphenol unit constituting the amorphous polyarylate, bisphenol is preferably used from the viewpoint of easy availability. Examples of such an amorphous polyarylate include, but are not particularly limited to, U Polymer manufactured by Unitika Co., Ltd. and Durel manufactured by Celanese Corporation in the United States.

[0029] The polymer alloys of the present invention can include one or more thermoplastic liquid crystal polymers and one or more amorphous polymers. The proportion of the amorphous polymer in the polymer alloy of the present invention is 1.0 to 2.9% by weight, and the proportion of the thermoplastic liquid crystal polymer is 97.1 to 99.0% by weight. When the proportion of the amorphous polymer is less than 1.0% by weight, sufficient end tear strength is not exhibited, and the object of the present invention cannot be achieved. On the other hand, when used in an amount larger than 2.9% by weight,
Conversely, the end crack strength is reduced, and physical properties such as electrical characteristics, low moisture absorption, humidity dimensional stability, and thermal expansion coefficient controllability, which are excellent characteristics of the thermoplastic liquid crystal polymer, are generated. The ratio of the amorphous polyarylate is 2 to 2.5% by weight.
Is preferred.

The polymer alloy of the present invention can be kneaded and granulated by a known thermoplastic polymer method. However, since the amount of the amorphous polymer is small, to provide a stable kneaded state, Use a twin screw kneading equipment, or a screw with a backflow mechanism in the kneading section,
It is preferable to use a kneading facility equipped with a screw devised to increase the pressure and temperature of the kneading section.

In the present invention, a polymer alloy film can be produced from the above-mentioned polymer alloy by utilizing the above-mentioned known method or a combination thereof. As the production method, for example, a well-known T-die film forming and stretching method, a laminate stretching method, an inflation method and the like are industrially advantageous. In particular, in the inflation method, stress is applied not only in the mechanical axis direction of the film (hereinafter abbreviated as the MD direction) but also in a direction orthogonal to the machine direction (hereinafter abbreviated as the TD direction). A biaxially oriented film having a good balance of thermal properties and thermal properties can be easily obtained.

In addition to the MD direction of the film,
As a method of applying a stress also in the D direction, (1) the traveling distance of the molten liquid crystal polymer in the gap space surrounded by the inner peripheral wall and the outer peripheral wall of the annular slit of the annular die is made sufficiently long so that the inner peripheral wall and the outer peripheral wall are A method of applying a shearing force parallel to the flow of the molten liquid crystal polymer, (2) a method of applying an oblique stress to the flow of the molten liquid crystal polymer by a rotating die, and (3) a mandrel for mixing and homogenizing the flow of the molten liquid crystal polymer. For example, (3-1) arranging a large number of hemispheres arranged in an oblique lattice pattern, (3-2) providing a spiral groove on the mandrel outer wall opposite to the winding direction of the spiral groove provided on the mandrel inner wall, and the like. A method of orienting a liquid crystal polymer using a devised mandrel can be used.

The above-mentioned biaxial orientation can be determined by using the degree of molecular orientation SOR of the biaxially oriented polymer alloy film as an index. The degree of molecular orientation SOR is preferably set to 1.3 or less. The biaxially oriented polymer alloy film is more practical because it has a good balance of mechanical properties and thermal properties in the MD and TD directions.

Here, the degree of molecular orientation SOR (Segment Orie
The term “ntation ratio” refers to an index that gives the degree of molecular orientation of a segment constituting a molecule.
Unlike OR (Molecular Orientation Ratio), it is a value in consideration of the thickness of the object. This molecular orientation degree SOR
Is calculated as follows.

First, in a well-known microwave molecular orientation measuring instrument, a biaxially oriented polymer alloy film is inserted into a microwave resonant waveguide such that the film surface is perpendicular to the direction in which the microwave travels. The electric field intensity (microwave transmission intensity) of the microwave transmitted through the film is measured. Then, based on the measured value, an m value (referred to as a refractive index) is calculated by the following equation. m = (Zo / △ z) X [1-νmax / νo] where Zo is a device constant, Δz is the average thickness of the object, and νmax
Is the frequency that gives the maximum microwave transmission intensity when the frequency of the microwave is changed, and vo is the frequency that gives the maximum microwave transmission intensity when the average thickness is zero (that is, when there is no object).

Next, when the rotation angle of the object with respect to the vibration direction of the microwave is 0 °, that is, the vibration direction of the microwave and the direction in which the molecules of the object are most oriented, and the minimum microwave transmission The degree of molecular orientation SOR is calculated by m0 / m90, where m0 when the direction in which the strength is given coincides with m0 and m when the rotation angle is 90 ° are m90.

As an unexpected effect of the present invention, a result that the film formation stability can be improved by the inflation method was obtained. That is, the molten resin extruded from the annular die is solidified while undergoing expansion and cooling, thereby preventing the bubble (tube-like film near the annular die) from being rolled, reducing the displacement, and stabilizing the bubble. Film formation was maintained.

[0038]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples. In the following examples, the melting point, film thickness,
The evaluation of the bubble swing width and the end crack strength was performed by the following methods. (1) Melting point Obtained by observing the thermal behavior using a differential scanning calorimeter. That is, after the raw material is heated at a rate of 20 ° C./min to completely melt it, the melt is rapidly cooled to 50 ° C. at a rate of 50 ° C./min, and then heated again at a rate of 20 ° C./min. The position of the endothermic peak that appeared was recorded as the melting point. (2) Film thickness Using a digital thickness gauge (manufactured by Mitutoyo Corporation), the obtained film is measured at 1 cm intervals in the TD direction, and the average value of 10 points arbitrarily selected from the center and the edge is defined as the film thickness. did. (3) Bubble swing width The displacement amount of the bubble end in the TD direction at a position 5 cm downstream in the MD direction from the position where the bubble of the molten resin extruded from the die has completed expansion was measured and defined as the bubble swing width. The case where the variation width was 5 mm or less was excellent, the case where 10-5 mm was good, and the case where 10 mm or more was bad. (4) End tear strength Five samples having a width of 10 mm and a length of 200 mm were sampled from the obtained film, and each sample was taken as 1 according to JIS C2318.
The value at the time of tearing by pulling at a speed of 0 mm / min was measured.

Example 1 p-hydroxybenzoic acid 75
% Of a thermoplastic liquid crystal polymer having a melting point of 285 ° C. and a copolymer of 25% by mole of 6-hydroxy-2-naphthoic acid and
8% by weight, a polyarylate resin (U-polymer, manufactured by Unitika Ltd.), which is an amorphous polymer, was mixed to 2% by weight, and melt-kneaded with a twin-screw extruder to 15 kg.
/ H and extruded with a continuous pelletizer to obtain a polymer alloy resin. Then, die clearance 500μ
m, melt-extrusion from an inflation die having an outer lip inner diameter of 40 mm, an inner lip outer diameter of 39 mm, and a die land length of 20 mm at a discharge rate of 9 kg / hour, and stretched under the conditions of a draft ratio of 5.2, a blow ratio of 3.2, and a thickness. 30
A μm biaxially oriented polymer alloy film was obtained. The roll of the bubble during inflation molding was as small as 6 mm, which was good. The molecular orientation degree SOR of the obtained biaxially oriented polymer alloy film was 1.03, and the end crack strength was 4.0.
It was 2 kg / cm. Table 6 shows the results.

[0040]

[Table 6]

Example 2 The amount of the thermoplastic liquid crystal polymer was 97.5% by weight, and the amount of the polyarylate resin was 2.5%.
The same as in Example 1 except that the thickness was 30% by weight.
A μm biaxially oriented polymer alloy film was obtained. The bubble sway during inflation molding was extremely small at 3 mm, which was excellent. The molecular orientation degree SOR of the obtained biaxially oriented polymer alloy film was 1.02, and the end tear strength was 4.8 kg / cm. Table 6 shows the results.

Example 3 The amount of the thermoplastic liquid crystal polymer was 97.1% by weight, and the amount of the polyarylate resin was 2.9.
The same as in Example 1 except that the thickness was 30% by weight.
A μm biaxially oriented polymer alloy film was obtained. The roll of the bubble during inflation molding is as small as 7 mm,
It was good. The molecular orientation degree SOR of the obtained biaxially oriented polymer alloy film was 1.03, and the end crack strength was 3.5 k.
g / cm. Table 6 shows the results.

Comparative Example 1 A 30 μm thick biaxially oriented heat was prepared in the same manner as in Example 1 except that the amount of the thermoplastic liquid crystal polymer was used at 100% by weight (ie, without mixing the polyarylate resin at all). A plastic liquid crystal polymer film was obtained. The lateral sway of the bubble during the inflation molding was as large as 12 mm, which was poor. The molecular orientation degree SOR of the obtained biaxially oriented thermoplastic liquid crystal polymer film was 1.05, and the end tear strength was 1.2 kg / cm. Table 6 shows the results.

Comparative Example 2 A biaxially oriented polymer alloy having a thickness of 30 μm was prepared in the same manner as in Example 1 except that the amount of the thermoplastic liquid crystal polymer was 95% by weight and the amount of the polyarylate resin was 5% by weight. A film was obtained. The roll of the bubble during inflation molding was as small as 7 mm, which was good. The molecular orientation degree SOR of the obtained biaxially oriented polymer alloy film was 1.03, and the end tear strength was 2.6 kg / cm.
Met. Table 6 shows the results.

[0045]

According to the present invention, by adding a small amount of the amorphous polymer without impairing the excellent properties of the thermoplastic liquid crystal polymer, the end effect can be improved as compared with the case where the amorphous polymer is not added at all. The crack strength can be improved to 2.5 times or more.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Toshiaki Sato 1621 Sazu, Kurashiki-shi, Okayama Prefecture F-term (reference) 4F071 AA43 AA44 AA45 AA48 AA50 AA57 AA62 AA64 AF12 AF16 AH12 AH13 BA01 BB07 BB09 BC01 4J002 CF042 CF161 CF162 CF181 CG002 CL081 CN012 CN032 GQ01

Claims (2)

[Claims] 1. A thermoplastic polymer capable of forming an optically anisotropic molten phase in an amount of 97.1 to 99.0% by weight and an amorphous polymer in an amount of 1.0 to 2.9% by weight (based on the total amount of the polymer). A polymer alloy comprising: 2. A film comprising the polymer alloy according to claim 1.