JPH01265417A - Electrical insulating film - Google Patents

Abstract

PURPOSE:To enhance heat resisting property and improve electrical insulating property by limiting ranges of heat shrinkage factor, rupture elongation and refraction factor in the thickness direction of a film made of biaxially plastic polyether ketonic resin. CONSTITUTION:A film made of biaxially plastic polyether ketonic resin having a heat shrinkage factor less than 3.0% at 150 deg.C, a rupture elongation 10% or more after heating at 280 deg.C for 500hrs, a refraction factor in the thickness direction less than 1.64 and F-5 value 11kg/mm<2> or more is used. The heat resisting property can be enhanced and the electrical insulation property can be improved by limiting the range of film making condition of the film because the heat resistance degradation of the biaxially heat plastic polyether ketonic resin changes with the fine structure of the film.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a film for electrical insulating materials that has excellent heat resistance and mechanical properties, as well as excellent film flatness, handling workability, and electrical characteristics. .

(Prior Art) Conventionally, biaxially oriented polyethylene terephthalate films have been characterized in that their mechanical properties 1. Due to its excellent electrical properties, heat resistance, chemical resistance, etc., it is widely used as an electrical insulating material.

However, in recent years, the properties required for films for electrically insulating materials have increased, and there are limits to the properties of biaxially oriented polyethylene terephthalate films, so there is a demand for films with even more excellent properties. For example, biaxially oriented polyethylene terephthalate film has a long-term heat resistance of E
Type (long-term heat resistance temperature: 120″C) or B type (long-term heat resistance temperature: 13
0°C), and when used as motor insulation or wire coating material, this long-term heat resistance limits miniaturization of motors and also makes it difficult to mount electrical components in areas exposed to high temperatures for long periods of time. Problems such as this have arisen.

Furthermore, if biaxially oriented polyethylene terephthalate is exposed to a high temperature environment for a long period of time, a large amount of oligomers will precipitate, resulting in various problems. For example, when biaxially oriented polyethylene terephthalate film is used for motor insulation in refrigerators, clogging due to oligomers precipitated by the refrigerant is the biggest cause of trouble, and even in such environments, there is a demand for films that do not precipitate oligomers. -ing By the way, polyetherketone is known as a crystalline thermoplastic polymer that is tough and has excellent heat resistance (Japanese Patent Publication No. 32642/1982, Japanese Patent Publication No. 10486/1983), and studies and proposals have been made to make it into a film. For example, Japanese Patent Application Laid-Open No. 57-137116 states that polyetherketone can be used in fields that take advantage of its heat resistance, such as insulating films for motors, insulating films for transformers, insulating films for capacitors, and flexible printed circuit boards. As expected, a method for producing a uniaxially oriented film by a rolling method is described. Furthermore, in Japanese Patent Application Laid-Open No. 61-3'7419, a biaxially oriented thermoplastic polyetherketone film is
It is described that it is suitable for the field of precision parts such as electrical and electronic parts such as capacitors, wire coatings, and flexible printed circuit boards, and recording media bases.

(Problem to be Solved by the Invention) Therefore, instead of the biaxially oriented polyethylene terephthalate film, which is a conventional electrical insulating material, a conventionally known thermoplastic polyetherketone resin film was used to make a tape for covering electric wires. Although an improvement was observed in terms of heat resistance, it became clear that further improvements were needed in terms of heat deterioration resistance, dielectric breakdown strength, flatness, etc.

An object of the present invention is to solve the problems of the prior art and to provide a film for electrical insulation material that has excellent heat resistance and electrical insulation properties, has a flat surface, and has excellent slipperiness and workability. It is in.

(Means for Solving the Problems) According to the present invention, the above object is a film made of a biaxially oriented thermoplastic polyetherketone resin, which has a heat shrinkage rate of 3.0% or less at 150°C. , 5 at 280℃
After heating for 00 hours, the elongation at break is 10% or more, the refractive index in the thickness direction is 1.64 or less, and the F-5 value is 11 kg/
m'' or more, and furthermore, by a film for electrical insulating materials characterized in that the surface roughness of the film is 0.005 to 0.10 pm. Ru.

The thermoplastic polyetherketone resin in the present invention is a structural unit or a polymer consisting of this unit and other structural units. Examples of other structural units include the following.

In the above structural unit, A is a direct bond, oxygen, -5O2
-1-CO- or a divalent lower aliphatic hydrocarbon group, Q and Q' may be the same or different, -C
O- or =SO2-, and n is 0 or 1. These polymers are disclosed in Japanese Patent Publication No. 60-32642, Japanese Patent Publication No. 61-10486, and Japanese Unexamined Patent Publication No. 57-137116.
It is stated in the publication number etc.

Thermoplastic polyetherketone resins contain polyarylene polyether, polysulfone,
It is also possible to blend resins such as polyarylate, polyester, and polycarbonate (also with stabilizers, antioxidants,
Additives such as ultraviolet absorbers may also be included.

As mentioned above, thermoplastic polyetherketone resins are known per se, and can be produced by methods known per se.

The above thermoplastic polyetherketone resin has an apparent melt viscosity at a temperature of 380'' C1 and an apparent shear rate of 200 degrees se.
c'' conditions are preferably in the range of 500 poise to 10000 poise, more preferably 1000 poise to 5000 poise, from the viewpoint of film formability and film properties.

The biaxially oriented thermoplastic polyetherketone resin film of the present invention has a heat shrinkage rate of 3.0% or less, preferably 2.0% or less, more preferably 1% or less when heat treated at 150°C for 30 minutes. and the elongation at break when heated at 280°C for 500 hours is 10% or more, preferably 1
It needs to be 5% or more, more preferably 20% or more. Outside this range, since the toughness is low, cracks are likely to occur when repeatedly bent in a high-temperature environment, and the film cannot withstand use as an electrically insulating material film.

Furthermore, the film for electrically insulating materials of the present invention has a refractive index in the thickness direction of the film of 1.64 or less, preferably 1.6.
2 or less, more preferably 1.61 or less, F-5
Value greater than 11 kg/un”, preferably 12k
g/mm2 or more, more preferably 13 kg/mm2 or more.

According to research by the present inventors, the heat deterioration resistance of plastic films has conventionally been determined by the heat resistance of the polymer itself that makes up the film, such as thermal decomposition resistance, oxidative decomposition resistance at high temperatures,
Although it was thought to be primarily determined by hydrolysis resistance, the surprising fact that the heat deterioration resistance of thermoplastic polyetherketone resin films varies depending on the film forming conditions, that is, the microstructure of the film. It became clear. The difference in heat deterioration resistance between a biaxially oriented film with a refractive index of 1.64 or less in the thickness direction and a film with a refractive index of more than 1.64 is particularly noticeable in the elongation at break after long-term heating.

That is, a biaxially oriented film with a refractive index of 1.64 or less in the thickness direction shows only a slight decrease in elongation at break after long-term heating, whereas a biaxially oriented film with a refractive index of 1.64 or less shows a slight decrease in elongation at break after long-term heating. The film weakens when heated for a short time, resulting in a significant decrease in elongation at break and a significant decrease in dielectric breakdown strength. Furthermore, as with the above-mentioned refractive index, when the F-5 value is less than 11 kg/ml112, the brittleness at high temperatures is significant, and therefore the failure elongation is significantly reduced.
Furthermore, the dielectric breakdown voltage decreases significantly.

Moreover, the surface roughness of the film of the present invention is 0.005 to 0.
．． 10 μm, preferably 0.01-0.07 pm,
More preferably, the surface roughness is 0.01 to 0.05 μm. If the surface roughness is less than 0.005 μm, it is difficult to obtain good slipperiness, and wrinkles may occur during film winding.
Blocking between films may occur, reducing workability in the processing process. On the other hand, the surface roughness is 0.10μm
If it exceeds this, although workability is improved, the dielectric breakdown voltage decreases or its dispersion increases.

The thermoplastic polyetherketone resin film of the present invention is
For example, (Tm+30)'C or Tm+90)'C
An unstretched film is obtained by melt-extruding a thermoplastic polyetherketone resin at a temperature of
~(T g +45) Stretched at a temperature of 1.5 times or more, especially 2.5 times or more at a temperature of ``C'' (Tg: glass transition temperature of polyetherketone resin), and then stretched in a direction perpendicular to the above stretching direction. (If the - stage stretching is in the vertical direction, the second stage stretching is in the horizontal direction) from (T g +10) to (T
g +40) It can be produced by stretching at a temperature of 2.5 to 5.0 times at a temperature of 'C. In this case, the area stretching ratio is preferably 4 times or more, more preferably 6 times or more. The stretching means may be either simultaneous biaxial stretching or sequential two-wheel stretching.

Furthermore, the film subjected to two-wheel stretching (T g +70
)℃~Tm''C. For example, for polyetheretherketone film,
It is preferable to heat set at 50 to 350°C. The heat setting time is, for example, 1 to 120 seconds.

The thickness of the thermoplastic polyetherketone resin film of the present invention can be arbitrarily set depending on its use.

As a means of adjusting the surface roughness of the film within the above range, it is possible to uniformly disperse substantially inert solid particles in the thermoplastic polyetherketone resin in the film, and adjust the particle size and content thereof. . The inert solid particles may be externally added particles or internal particles, and may be, for example, metal salts of organic acids, inorganic substances, special resins, etc. Preferred inert solid particles include: (1) calcium carbonate, (2) silicon dioxide (including hydrates, diatomaceous earth, silica sand, quartz, etc.), (2) alumina, and (2) silicates containing 30% by weight or more of 5i02. For example, amorphous or crystalline clay minerals, aluminosilicate compounds (including calcined materials and hydrates), warm asbestos, zircon, fly ash, etc.), Mg, Zn, Zr, and Ti.
oxides, ■ sulfates of Ca and Ba, ■ phosphates of Li, , Na and Ca (including monohydrogen salts and dihydrogen salts), ■ L
i, benbrozoate of Na and K, terephthalate of Ca, Ba, Zn and Mn, @1Mg, ca s B
a % Z n.

Cd % P b −S r SM n SF e −
, Co and Ni titanates, ■Ba and PB chromates, ■Carbon (e.g. carbon black, graphite, etc.), ■Glass (e.g. glass powder, glass peas, etc.),
Examples include @MgC0, ■fluorite, @Z n S and O silicone resin. Preferred examples include anhydrous silicic acid, hydrated silicic acid, aluminum oxide, aluminum silicate (including calcined products, hydrates, etc.), monolithium phosphate, trilithium phosphate, sodium phosphate, calcium phosphate, barium sulfate, titanium oxide, Lithium benbrozoate, double salts of these compounds (including hydrates), glass powder, viscosity (including kaolin, bentonite, clay, etc.), talc, diatomaceous earth,
Examples include silicone resin. The average particle size of these inert solid particles is usually 0.01-3 μm, preferably 0.05-2 μm, more preferably 0.1-1.
It is 5 μm. Further, the content of these inert solid particles is usually 0.0% relative to the thermoplastic polyetherketone resin.
0.005 to 1% by weight, preferably 0.01 to 1% by weight, more preferably 0.01 to 0.5% by weight.

In addition, among the above inert solid particles, the average particle size is 0.0
Spherical silica fine particles having a diameter of 5 to 4 μm and a particle diameter ratio (major axis/breadth axis) of 1.0 to 1.2 may be used alone or in a proportion other than the above to have a content of 0.01 to 3.0% by weight. When mixed with inert solid particles and dispersed in a thermoplastic polyetherketone resin, or when the average particle size is 0.01 to 4.
Volume shape coefficient a(f) defined as p m-, f = V/D3 (here T:, ■ indicates the average volume of the particles (μm'), D indicates the average maximum particle diameter (μm) of the particles) is 0.4~. g
/ 6, and the general formula Rx S i 0x-xzz (
Here, R is a hydrocarbon group having 1 to 7 carbon atoms, and X is 1 to 1.
The silicone resin fine particles represented by 2) are mixed alone or with the other inert solid particles mentioned above so that the content is 0.005 to 3.0% by weight, and the silicone resin fine particles represented by 2) are added to a thermoplastic polyetherketone resin. When dispersed, spherical silica particles,
It is particularly suitable because it has a high affinity between silicone resin fine particles and polyetherketone resin, so voids are less likely to occur around the particles when biaxially oriented, and a film with good electrical insulation can be formed. It is. in this case,
The spherical silica fine particles are preferably substantially spherical, have a sharp particle size distribution, and are close to monodisperse, and are not limited in any way to their manufacturing method or other aspects. In particular, it is desirable that the relative standard deviation expressed by the following formula is 0.5 or less.

Relative standard deviation = Here, Di 2 Area circle equivalent diameter of individual particles (μm) D = Surface area sum equivalent diameter average value (μm) n: represents the number of particles.

For example, spherical silica particles are made of ethyl orthosilicate (S
Hydrolyzed silica (S i (OH) a ) monodisperse method is created from the hydrolysis of i (OCz H!) 4), and this hydrous silica monodisperse method is further dehydrated to form silica bonds (
S i -0-3i=) can be manufactured by three-dimensionally growing (Journal of the Chemical Society of Japan 81. N009, P.
1503).

S i (OC2H5) a +4 Hz O→S i
(OH) 4 + 4 Cz Hs 0H=S i
-OH+HO-3i= →=S i -0-3i= +H,0 On the other hand, silicone resin fine particles are preferably substantially spherical, have a sharp particle size distribution, and are close to monodisperse. It is not limited in any way. In particular, it is desirable that the particle size distribution (r) expressed by the following formula is 1 to 1.4.

T=D□/D7゜ Spherical silicone resin particles are The following formula (A) It has the composition represented by.

R in the above formula (A) is a hydrocarbon group having 1 to 7 carbon atoms, and is preferably an alkyl group having 1 to 7 carbon atoms, a phenyl group, or a tolyl group. The alkyl group having 1 to 7 carbon atoms may be linear or branched, for example,
Methyl, ethyl, n-propyl, 1so-propyl, n
-butyl, iso-butyl, tert-butyl, n
-pentyl, n-hebutyl, etc. can be mentioned.

Among these, R is preferably methyl and phenyl, with methyl being particularly preferred.

X in the above formula (A) is a number from 1 to 1.2.

When X is 1 in the above formula (A), the above formula (A)
can be represented by the following formula (A)-1 R3iO+, s... (A)-1 [Here, the definition of R is the same as above].

The composition of the above formula (A)-1 originates from the following structural part in the three-dimensional polymer chain structure of the silicone resin: -0-3i-0-.

Moreover, when X is 1.2 in the above formula (A), the above formula (A) is the following formula (A)-2 R+, z S 101.4 ...... (A)-
2 [Here, the definition of R is the same as above].

The composition of the above formula (A)-2 is the structure 0.
It is understood that it consists of 8 moles and 0.2 moles of the structure represented by the following formula (A)' R, SiO... (A)' [Here, the definition of R is the same as above] can do.

The above formula (A)' originates from the following structural part in the three-dimensional polymer chain of silicone resin: -0-3i-0-.

As understood from the above explanation, the composition of the above formula (A) may consist essentially only of the structure of the above formula (A)-1, or the structure of the above formula (A)-1 and the above formula ( A)-
It can be seen that the two structures coexist in a state where they are randomly bonded at an appropriate ratio.

The spherical silicone resin fine particles preferably have the formula (A) above.
, X has a value between 1 and 1.1.

These silicone resin particles are produced by, for example, hydrating trialkoxysilane or a partial hydrocondensate represented by the following formula (%) in the presence of ammonia or an amine such as methylamine, dimethylamine, ethylenediamine, etc., with stirring. It can be produced by decomposition and condensation. According to the above method using the above starting material, silicone resin particles having the composition represented by the above formula (A)-1 can be produced.

Rz Si (OR')! If the dialkoxysilane represented by the above formula (A) is used together with the above trialkoxysilane and the above method is followed, the above formula (A)
Silicone resin particles having a composition represented by -2 can be produced.

(Example) Hereinafter, the present invention will be explained in more detail with reference to Examples. In addition, various physical property values and characteristics were measured by the following methods.

(1) Measurement of heat shrinkage rate Samples are marked with marked lines at 30cm intervals, and heated in a tension-free state for a certain period of time (150"C x
It was calculated from the change in sample length after 30 minutes) using the following formula.

Heat shrinkage rate = The heat shrinkage rate of the film in the vertical and horizontal directions is measured,
The average value was taken as the representative value.

(2) Heat Deterioration Resistance After heating at 280° C. for 1500 hours in a stress-free state using a gear aging tester, the dielectric breakdown voltage and elongation at break are measured at room temperature.

a) Breakdown voltage Implemented according to JIS C2318.

b) Breaking elongation A sample cut to a sample width of 10 mm and length of 150 mm was placed in an Instron-type universal tensile tester under the conditions of a tensile speed of 10 min/min and a chart speed of 50 m/min with 100 plates between chucks. and pull at room temperature. Original length lO1 When the length at break is l, it is expressed as ((f-1o)/j!o) x 100%.

(3) Refractive index A light wavelength of 589 nm (N a
(center of line D) at a temperature of 20°C.

(4) Cut the F-5 value film into a sample with a thickness of 10 mm and a length of 15 cm.
char) Pull the sample (film) using an Instron type universal tensile tester at room temperature at a speed of somm/min, and divide the load at 5% elongation by the initial cut from the obtained load-elongation curve. It was calculated by

(5) Average particle diameter (DP) of particles Shimadzu CP-50 type Centrifugal Particle Size Analyzer (Cenrifugal Pa
It was measured using a ticle 5ize Analyser). From the integrated curve of particles of each particle size and their abundance calculated based on the obtained centrifugal sedimentation curve, the particle size corresponding to 50 mass percent is read, and this value is used as the above average particle size. ” Published by Nikkan Kogyo Shimbun.

1975, pp. 242-247).

(6) Film surface roughness (Ra) CL A (Center Line Average
- Center line average roughness) Measured according to JIS B 0601. Stylus type surface roughness meter (SU) manufactured by Tokyo Seimitsu Co., Ltd.
RFCOM3B), needle radius 2μ, load 0.0
A chart (film surface roughness curve) was drawn under the condition of 7 g. A part of the measurement length is extracted from the film surface roughness curve in the direction of its center line, and the center line of this extracted part is taken as the X axis, and the direction of vertical magnification is taken as the Y axis, and the roughness curve Y is
When expressed as = f (X), the value (Ra: μm) given by the following formula is defined as the flatness of the film surface.

In the present invention, eight pieces are measured with a reference length of 0.25 mm,
Ra was expressed as the average value of 5 values excluding 3 from the highest value.

(7) Workability The winding workability and process passability in the film forming and processing steps were comprehensively divided into the following three stages.

O: Excellent slipperiness, good workability and process passability.

Δ: Generally good workability and process passability are obtained, but the smoothness is inferior to ○.

×: Wrinkles appear in the winding process, end faces become uneven, and process passability is poor.

(8) Comprehensive evaluation The heat resistance, mechanical, electrical properties, and workability were comprehensively evaluated, and those that were extremely good in all were rated ◎, and those that were good and those with poor O1 were rated ×.

Examples 1 to 10 Comparative Examples 1 to 4 Inert particles shown in Table 1 were added to thermoplastic polyetherketone (manufactured by IC1: Polyetherketone 380C).
After mixing in the ratio shown in the table and blending, use an extruder to
An unstretched film was prepared by extrusion at 0°C and cast onto a casting drum maintained at a temperature of 80°C, which was then biaxially stretched at 160'C at the stretching ratios in the longitudinal and transverse directions shown in Table 1. The film was then heat-set for 30 seconds at the temperature shown in Table 1 to obtain a biaxially oriented film with a thickness of 25 μm. The properties of the obtained film were as shown in Table 1.

(This page, blank space below) As is clear from the above results, the biaxially oriented films of the present invention (Examples 1 to 10) all have good heat resistance, mechanical properties,
It can be seen that it has excellent electrical characteristics and workability.

(Effects of the Invention) As detailed above, the film for electrical insulating materials of the present invention has excellent heat resistance, mechanical and electrical properties, and handling workability, and is suitable for use in motors, transformers, capacitors, electric wires, cables, communications, etc. It can be suitably used for electrical parts such as devices, flexible printed circuits, and liquid crystal panel substrates.

Claims (2)

[Claims] (1) A film made of biaxially oriented thermoplastic polyetherketone resin, which has a heat shrinkage rate of 3.0% or less at 150°C and a breaking elongation of 10% after heating at 280°C for 500 hours. As described above, the film for electrically insulating material is characterized by having a refractive index in the thickness direction of 1.64 or less and an F-5 value of 11 kg/mm^2 or more. (2) Film surface roughness of 0.005 to 0.10 μm
The film for electrically insulating material according to claim 1, characterized in that: