JPH048456B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] This invention relates to 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 to incorporate inert inorganic particles into a biaxially oriented poly-p-phenylene sulfide film in order to improve its properties.
For example, 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 to the polymer for the purpose of adjusting the surface roughness of the film. It is disclosed that a certain amount remains. Also, JP-A-60-
No. 257510 discloses that when a biaxially oriented poly-p-phenylene sulfide film is used as a capacitor dielectric, fine protrusion density and coarse protrusion density are Biaxially oriented poly-p-
A phenylene sulfide film is disclosed, and in order to adjust the fine protrusion density and the coarse protrusion density, the average particle size may be added to the resin composition at any stage before the melt extrusion process, if necessary. 1.5μm
It is disclosed that the fine particles of Furthermore, in Tokuko No. 59-5101, inert inorganic particles were added to suppress the friction coefficient to 0.75 or less.
Also disclosed is a biaxially oriented poly-p-phenylene sulfide film whose average surface roughness is suppressed to 0.09 μm/5 mm or less. However, when a relatively large amount of inorganic particles are added to a biaxially oriented poly-p-phenylene sulfide film, coarse protrusions are likely to occur in the film due to the inclusion of coarse substances in the particles and coarse particles due to poor dispersion. That part becomes an insulation defect. Further, a poly-p-phenylene sulfide film containing inorganic particles produces voids around the particles during stretching, resulting in insulation defects. If the amount added is increased in order to increase the protrusion density and improve the slipperiness of the film, insulation defects will further increase due to these voids. Furthermore, if the amount of inorganic particles added is reduced to about 1.5% by weight or less, the coefficient of friction will generally increase, making it difficult to handle the film, and when the film is used as a dielectric for a capacitor, it may become difficult to wind the element. Insulation defects increase in the subsequent pressing process. [Problems to be Solved by the Invention] An object of the present invention is to provide a biaxially oriented poly-p-phenylene sulfide film that has good sliding properties but has few coarse protrusions and insulation defects. It is. [Means for Solving the Problems] As a result of intensive research, the inventors of the present application found that if the internal haze and external haze per film thickness are within a specific range, the amount of inert inorganic particles blended can be reduced. The present invention was completed based on the discovery that good slip properties can also be obtained. That is, this invention uses inert inorganic particles as 0.3
Biaxially oriented poly-p containing 1.5% by weight, internal haze per thickness of 1%/μm to 3%/μm, and external haze of 5% to 20%.
-Providing a phenylene sulfide film. [Effects of the Invention] The biaxially oriented poly-p-phenylene sulfide film of the present invention has a relatively small amount of inert inorganic particles, so it has few coarse protrusions and insulation defects, and has good slip properties. be. The film of the present invention has good slip properties, making it easy to handle, and has few insulation defects, so it exhibits excellent performance when used as a dielectric material for capacitors. [Specific Description of the Invention] In this specification, poly-p-phenylene sulfide means that 70 mol% or more (preferably 85 mol% or more) of the 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 obtained film will be impaired. Less than 30 mol% (preferably 15 mol%) of repeating units
(less than), there is no problem even if a unit containing a copolymerizable sulfide bond is included. For example, such a unit is

【formula】

【formula】

【formula】

【formula】

[Formula] (R is -COOH or -SO ₃ H, X is -
CH ₂ −, −CH ₂ CH ₂ −, or

[Formula]) can be mentioned. The biaxially oriented poly-p-phenylene sulfide film of this invention contains 0.3% by weight of inert inorganic particles.
1.5% by weight, preferably 0.3% to 1.2% by weight. If the content of inert inorganic particles is less than 0.3% by weight, the slipperiness of the film will be poor, and if it exceeds 1.5% by weight, insulation defects will increase. The average particle size of the inert inorganic particles is preferably from 0.01 to 5 μm;
More preferably, it is 0.05 μm to 2 μm. Any inorganic particles can be used as the inert inorganic particles as long as they do not substantially react with poly-p-phenylene sulfide, for example,
Examples include calcium carbonate, silica, kaolin, talc, barium sulfate, alumina, zinc oxide, and titanium oxide. The internal haze per thickness of the biaxially oriented poly-p-phenylene sulfide film of this invention (internal haze (%)/thickness (μm)) is 1%/μm to 3
%/μm. Internal haze per thickness is 1%/
If it is less than μm, the slipperiness of the film will be poor, and 3
%/μm, insulation defects increase. Furthermore, the external haze of the biaxially oriented poly-p-phenylene sulfide film of the present invention ranges from 5% to 20%.
%. The external haze is the total haze minus the internal haze; if it is less than 5%, the slipperiness will be poor, and if it exceeds 20%, the mechanical properties of the film will be poor and it will become brittle. The thickness of the film is preferably from 0.3 μm to 150 μm, more preferably from 0.3 μm to 25 μm, and even more preferably from 0.5 μm to 10 μm. The film may also contain less than 10% by weight of other additives such as other polymers, lubricants, colorants and/or UV absorbers. The biaxially oriented poly-p-phenylene sulfide film of the present invention can be produced as follows. First, poly-p-phenylene sulfide resin powder produced by a conventional method and inert inorganic particles are mixed in the above weight ratio, and this resin composition is processed by a conventional method using an extruder such as an extruder. The film is melt-extruded and then cooled and solidified to obtain an amorphous film. At this time, if desired, less than 10% by weight of other polymers, lubricants, colorants, ultraviolet absorbers, etc. may be added to the resin composition. Next, this amorphous film is stretched in the longitudinal direction (MD) and the transverse direction (TD). Stretching can be carried out by either sequential biaxial stretching or simultaneous biaxial stretching, but sequential biaxial stretching is preferably carried out. Film temperature during longitudinal stretching ranges from 97℃ to 120℃
The temperature range is preferably from 100°C to 110°C. If it is below 97°C, the resulting film will have insufficient slip properties, and if it exceeds 120°C, film formability will deteriorate. The heating time is preferably from 0.2 seconds to 20 seconds, particularly preferably from 0.2 seconds to 10 seconds. The heating method is not particularly limited, and any known heating method such as heating rolls, hot air, and radiation heaters can be employed. The stretching means is also not particularly limited, but it is usually carried out using a plurality of rolls. The stretching ratio is not particularly limited, but is, for example, 3.2 times to 4.5 times. The external haze of the biaxially oriented poly-p-phenylene sulfide film can be adjusted by adjusting the temperature and heating time in the longitudinal stretching process, so that the external haze falls within the above range. Adjust these conditions. When the sequential biaxial stretching method is adopted, stretching in the width direction can be carried out by a conventional method using, for example, a tenter. The stretching ratio is not particularly limited, but for example
It is 3.0 to 3.8 times. Next, the thus stretched film is subjected to a constant length heat treatment at 240°C to 290°C for 1 to 50 seconds in a conventional manner to obtain a biaxially stretched poly-p-phenylene sulfide film of the present invention. . Note that the internal haze depends on the amount of inert inorganic particles added, the particle size, and the degree of dispersion thereof, so these are appropriately selected within the above range so that the internal haze per thickness is within the range of this invention. . [Example] Next, Examples and Comparative Examples of the present invention will be shown to specifically explain the effects of the present invention. In each example, haze, insulation defects, coefficient of friction, strength and elongation were measured as follows. Haze Measured according to JIS K-6714. Note that the total haze was measured by measuring the test piece in the atmosphere, and the internal haze was measured by immersing the test piece in a quartz cell containing tetralin. Moreover, the external haze was calculated by subtracting the internal haze from the total haze. Insulation defect Aluminum is deposited on one side of the film so that the surface resistance is approximately 3 ohms, and the non-deposited side is placed on a metal mirror plate facing down, and a DC voltage of 150 V per 1 μm of film thickness is applied between the metal plate and the deposited surface. was applied, the number of locations where dielectric breakdown occurred was counted, and the number was converted to the number ^per square meter of film area, which was used as an index of insulation defects. Friction Coefficient According to ASTM D-1894B method, the static friction coefficient between film surfaces was measured at 20° C. and 65% RH. Strength and elongation Measured according to JIS C-2318 method at 20°C and 65% RH. Example 1, Comparative Examples 1 and 2 Calcium carbonate with an average particle size of 1.0 μm, respectively.
A poly-p-phenylene sulfide composition containing 0.1, 0.5, or 2.0% by weight was melt-extruded and solidified by cooling on a cast drum to obtain an amorphous film. Then, after contacting with a roll heated to 105°C,
3.6 in the longitudinal direction (MD) between rolls with different circumferential speeds
Stretch it twice and use a tenter at 100℃ in the width direction (TD).
Stretched 3.4 times and heat treated at 260℃ for 5 seconds to reduce thickness.
A biaxially oriented poly-p-phenylene sulfide film of 2 μm was obtained. This film was measured for internal haze, external haze, coefficient of friction, and insulation defects. The results are shown in Table 1.

[Table] Example 2, Comparative Examples 3 and 4 Silica 1.5 with different average particle diameters prepared by the method of Example 1
Added wt%, different thickness of internal haze 3.5μm
A film was prepared and its friction coefficient and insulation defects were measured. The results are shown in Table 2.

【table】

[Table] Example 3, Comparative Examples 5 and 6 Using the method of Example 1, 6 μm thick films with different external hazes were prepared by changing the MD stretching temperature, and their friction coefficients, strength and elongation were measured. The results are shown in Table 3.

【table】

Claims (1)

[Claims] 1 Contains 0.3% to 1.5% by weight of inert inorganic particles, has an internal haze per thickness of 1%/μm to 3%/μm, and has an external haze of 5% to 20%
% biaxially oriented poly-p-phenylene sulfide film.