JPH048455B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] This invention relates to a method for producing a biaxially oriented poly-p-phenylene sulfide film. [Prior art and its disadvantages] Biaxially oriented poly-p-phenylene sulfide film has extremely excellent performance in terms of heat resistance, chemical resistance, electrical insulation, dielectric properties, mechanical properties, etc. It is attracting attention as a heat-resistant electrical insulating material. It has been known that in order to improve the properties of a biaxially oriented poly-p-phenylene sulfide film, inert inorganic particles may be added thereto.
Specifically, JP-A No. 55-34968 discloses that inert inorganic particles are added to the polymer during or at the end of polymerization, or insoluble salts used for polymerization are added for the purpose of adjusting the surface roughness of the film. It is disclosed that a certain amount remains. However, the method of adding inert inorganic particles during polymerization and the method of leaving a certain amount of insoluble salts used for polymerization, because this polymerization is solution polymerization using a strong basic solvent, It is difficult to finely disperse the particles, and coarse particles tend to form. Furthermore, when adding a mixture of the produced polymer and inert inorganic particles, many coarse particles are observed, and it is difficult to reduce these coarse particles. It causes insulation defects when used in Furthermore, in JP-A No. 60-257510, in order to reduce variations in capacitance and dielectric breakdown voltage when biaxially oriented poly-p-phenylene sulfide film is used in capacitors, Biaxially oriented polyester with coarse protrusion density adjusted within a certain range
A p-phenylene sulfide film is disclosed, and in order to adjust the fine projection density and the coarse projection density, the average particle size may be added to the resin composition at any stage before the melt extrusion process, if necessary. 0.1~1.5μm
It is disclosed that the fine particles of However, even in this case, there is a problem that coarse particles are generated due to secondary aggregation of fine particles, and the smaller the particle size of the added particles, the more coarse particles are likely to be generated due to secondary aggregation. It is easy to cause insulation defects. As described above, it has been known that inert inorganic particles are added to biaxially stretched poly-p-phenylene sulfide film to improve its properties. , and the resulting problem of insulation defects in the film. [Problems to be Solved by the Invention] An object of the present invention is to provide a biaxially oriented poly-p-phenylene film that can suppress the formation of coarse particles and uniformly disperse inert inorganic particles in the film. An object of the present invention is to provide a method for manufacturing a liquid film. [Means for solving the problem] As a result of intensive studies, the inventors of the present application adopted inert inorganic particles having an average particle size and apparent specific gravity within a certain range, and Poly-p- having a particle size that satisfies a specific relationship with respect to specific gravity
We have discovered that by mixing phenylene sulfide resin powder and the above-mentioned inert inorganic particles and melting and extruding the mixture, the inert inorganic particles can be uniformly dispersed in a film without forming almost any coarse particles. completed this invention. That is, this invention uses a resin powder whose main component is poly-p-phenylene sulfide, an average particle size of 0.01 μm to 5.0 μm, and an apparent specific gravity of 20 g/m to 5.0 μm.
A method for producing a biaxially oriented poly-p-phenylene sulfide film by mixing 2000 g of inert inorganic particles and melt-extruding the same, the resin powder having a particle size equal to that of the inert inorganic particles. For _the apparent specific gravity _of Biaxially oriented poly-p-
A method for producing a phenylene sulfide film is provided. [Effects of the Invention] According to the method of the present invention, the dispersibility of inert inorganic particles in the film is improved, the number of coarse particles is small, and as a result, a film suitable for capacitor applications with few insulation defects can be produced. can do. [Detailed Description of the Invention] As described above, the method of the present invention uses a poly-p-phenylene sulfide resin powder having a particle size in a specific range and an inert resin powder having an average particle size and apparent specific gravity in a specific range. A film is produced by mixing with inorganic particles and melt-extruding the mixture. The average particle size of the inert inorganic particles used in the method of this invention is from 0.01 μm to 5.0 μm, and their apparent specific gravity is from 20 g/ to 2000 g/, preferably 20 g/
800g/. Examples of inorganic particles that can be used include silica, calcium carbonate, titanium oxide, aluminum silicate, calcium phosphate, kaolin, etc., but other inorganic particles can also be used, satisfying the above requirements and producing poly-p-
Any inorganic particles can be used as long as they do not substantially react with phenylene sulfide. In this specification, poly-p-phenylene sulfide means that 70 mol% or more (preferably 85 mol% or more) of repeating units have the general formula Refers to a polymer consisting of the structural units shown below. If such a component is less than 70 mol%, the crystallinity, thermal transition temperature, etc. of the polymer will be low, and the heat resistance, dimensional stability, mechanical properties, etc. of the resulting film and laminate thereof will be impaired. A unit containing a copolymerizable sulfide bond may be included as long as it is less than 30 mol% (preferably less than 15 mol%) of the repeating units. In addition, in this specification, a resin powder containing poly-p-phenylene sulfide as a main component refers to a resin powder containing 90% by weight of the above-mentioned poly-p-phenylene sulfide.
Refers to powder containing more than If the content of poly-p-phenylene sulfide is less than 90% by weight, the crystallinity, thermal transition temperature, etc. of the powder will be low, and the heat resistance, dimensional stability, mechanical properties, etc. of the obtained film and its laminate will be reduced. damage. The remaining less than 10% by weight of the resin powder may consist of polymers other than poly-p-phenylene sulfide, organic fillers, and the like. Further, additives such as organic lubricants, colorants, and ultraviolet absorbers may also be included. In the method of this invention, the resin powder whose main component is poly-p-phenylene sulfide is
The inert inorganic particles have a particle size D ₅₀ that satisfies the following formula with respect to the apparent specific gravity SG (g/). D ₅₀ ≦log (SG/10) Here, the particle size D ₅₀ is the particle size when the cumulative amount of residue on the sieve obtained in the sieving test is the total amount of the sample.
It represents the particle size (mm) when it becomes 50% by weight. The particle size _D50 of the resin powder containing poly-p-phenylene sulfide as a main component preferably satisfies the following formula. D ₅₀ ≦0.8log (SG/10) Resin powder containing poly-p-phenylene sulfide as a main component can be obtained by a conventional method, but if the particle size of the powder obtained by a conventional method satisfies the above formula. If not, the powder is pulverized using a ball mill, jet pulverizer, attrition type pulverizer, etc. to a particle size that satisfies the above formula. Next, the resin powder containing poly-p-phenylene sulfide as a main component and the inert inorganic particles are uniformly mixed. The mixing ratio of inorganic particles is 50% by weight or less, preferably 35% by weight based on the total amount of the composition after mixing.
% by weight or less. This composition can be used alone or in combination of two or more similarly prepared compositions with different types and concentrations of inorganic particles, and can be used as a poly-p-phenylene sulfide resin to which no inorganic particles are added. It is diluted or directly extruded from an extruder to form a film. In this case, the composition mixed as described above is first melt-extruded using an extruder to obtain a chip-shaped composition, and this is mixed with other chip-shaped poly-p-phenylene sulfide resin as desired. It can also be melt extruded using an extruder. In any case, it is essential to the present invention that each powder mixture such that the particle size of the resin powder and the apparent specific gravity of the inert inorganic particles satisfy the above relational expression is melt-kneaded using an extruder at least once. This is a requirement. The melt viscosity of the resin composition is preferably in the range of 500 to 12,000 poise (more preferably 700 to 7,000 poise) at a temperature of 300°C and a shear rate of 200 sec ^-1 from the viewpoint of film moldability. The content of inert inorganic particles in the obtained film is preferably 0.05% to 2.0% based on the weight of the film. The obtained film is then biaxially stretched in a conventional manner and, if necessary, heat treated. [Examples of the Invention] Next, Examples and Comparative Examples of the invention will be shown to specifically explain the effects of the invention. The average particle size, apparent specific gravity, particle size D ₅₀ , number of coarse particles, and number of insulation defects were measured as follows. Average particle size: Determined by microscopy. The fine particles were observed with an optical or electron microscope, the maximum diameter in a certain direction was taken, and the average value was determined. Apparent specific gravity SG (g/) Compliant with JIS K5101. Particle size D ₅₀ Conformed to the sieving test of JIS R5201-1981. Coarse grain By microscopy. That is, particles with a major diameter of 10 μm or more were counted from images of internal particles in the film captured by the transmission method. Insulation defect Shinchiyu electrode (150mm x 200mm, surface roughness
2S or less) and the aluminum surface of the aluminum vapor-deposited polyester film.
mm) were placed in close contact with each other, and a DC voltage of 150 V/μm was applied for 90 seconds, and the number of broken pieces was counted. Example 1 32.6 kg of sodium sulfide in an autoclave
(250 mol, containing 40% by weight of water of crystallization), 100 g of sodium hydroxide, 36.1 kg (250 mol) of sodium benzoate, and N-methyl-2-pyrrolidone (hereinafter
After 79.2 kg of NMP (abbreviated as NMP) was charged and dehydrated at 205°C, 37.5 kg (255 mol) of 1,4-dichlorobenzene and 20.0 kg of NMP were added and reacted at 265°C for 4 hours. The reaction product was washed with water and dried to obtain 21.1 kg (yield: 78%) of poly-p-phenylene sulfide consisting of 100 mol % of p-phenylene sulfide units and having a melt viscosity of 3100 poise. Particle size of this powder
D ₅₀ was approximately 1.9 mm. Next, this poly-p-phenylene sulfide (hereinafter abbreviated as PPS) powder was ground for 2 hours using a hammer mill to obtain a powder having a particle size _D50 of about 0.5 mm. Silica powder with an apparent specific gravity SG of approximately 50 g/m and an average particle size of 2.3 μm was mixed with ground PPS powder for 15 minutes using a Henschel type mixer so that the concentration was 5% by weight. This mixture was melt-extruded at 300 to 320°C using a twin-screw extruder with a diameter of 40 mm, molded into guts, and then chipped. Next, this chip is combined with a PPS resin chip with no added inorganic particles and a silica concentration of 0.5% by weight.
Calcium stearate
Added 0.05% by weight, melted at 310℃ using a 40mm diameter extruder, and cast onto a casting drum whose surface was kept at 25℃ to a thickness of 52μm.
An unstretched film was obtained. This film is passed through a longitudinal stretching device consisting of a group of rolls at a film temperature of 100°C and a stretching speed of 3000%/
Temperature using a tenter followed by stretching 3.5 times in minutes
Transversely stretched 3.5 times at 100℃ and a stretching speed of 1000%/min, and then stretched at 270℃ in a subsequent heat treatment chamber in the same tenter.
A biaxially oriented polyester film with a thickness of 4 μm was heat treated for 5 seconds.
p-phenylene sulfide film (film A
) was obtained. Separately, for comparison, PPS powder (D ₅₀ = approximately 0.8 mm) that had been ground for 30 minutes was mixed with the same silica powder at the same concentration, formed into a film in the same way, and biaxially stretched to a thickness of 4 μm. A poly-p-phenylene sulfide film (referred to as film B) was obtained. For the obtained films A and B, the number (pieces/m ² ) of coarse particles (particle size ≧10 μm) and the number (pieces/m ² ) of insulation defects were measured. The results are shown in Table 1. From Table 1, it can be seen that Film A produced by the method of the present invention is an excellent film with fewer coarse grains and fewer insulation defects.

[Table] Example 2 Evaluation of a biaxially oriented film obtained by adding various calcium carbonate particles having different average particle diameters and apparent specific gravity to the film at a concentration of 1.0% by weight in the same manner as in Example 1. The results are shown in Table 2. From Table 2, it can be seen that the film produced by the method of the present invention has fewer coarse grains and is an excellent film with fewer insulation defects.

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Claims (1)

[Claims] 1. A resin powder containing poly-p-phenylene sulfide as a main component, and an average particle size of 0.01 μm to 5.0 μm,
A method for producing a biaxially oriented poly-p-phenylene sulfide film by mixing with inert inorganic particles having an apparent specific gravity of 20 g/ to 2000 g/, and melt-extruding the mixture, the method comprising: D ₅₀ ≦log (SG/10) where the particle size is the apparent specific gravity of the inert inorganic particles (in the above formula, D ₅₀ is the particle size of the resin powder, and SG is the apparent specific gravity of the inert inorganic particles). ) A biaxially oriented poly-p-
Method for producing phenylene sulfide film. 2 The particle size of the resin powder is D ₅₀ ≦0.8 log (SG/10) with respect to the apparent specific gravity of the inert inorganic particles (in the above formula, D ₅₀ is the particle size of the resin powder, and SG is the inert Claim 1, which satisfies the formula expressed by (representing the apparent specific gravity of inorganic particles)
The method described in section. 3. The method according to claim 1 or 2, wherein the inert inorganic particles have an apparent specific gravity of 20 g/ to 800 g/. 4. The method according to any one of claims 1 to 3, wherein the mixing ratio of the inert inorganic particles is 50% or less based on the weight of the resin powder.