JPH0766694B2 - Film for electrical insulation materials - Google Patents

Description

TECHNICAL FIELD The present invention relates to a film for an electric insulating material, which is excellent in heat resistance and mechanical properties, and is excellent in flatness, handling workability and various electrical properties of the film. .

(Prior Art) Conventionally, a two-wheel oriented polyethylene terephthalate film has been widely used for electrical insulating materials because of its excellent mechanical properties, electrical properties, heat resistance, chemical resistance and the like.

However, in recent years, the properties required for a film for an electric insulating material have increased, and the properties of a two-wheel oriented polyethylene terephthalate film have limitations, so that a film having more excellent properties has been demanded. For example, biaxially oriented polyethylene terephthalate film has long-term heat resistance of E
Type (long-term heat resistance temperature: 120 ° C) to Type B (same: 130 ° C), when used as a motor insulation and wire coating material, downsizing of the motor is restricted due to this long-term heat resistance, and further high temperature There is a problem that it becomes difficult to mount an electric component on a part exposed to the heat for a long time.

Further, when the biaxially oriented polyethylene terephthalate is exposed to a high temperature environment for a long period of time, a large amount of oligomers are deposited, which causes various problems. For example, when a biaxially oriented polyethylene terephthalate film is used for motor insulation for refrigerators, clogging is the largest cause of trouble due to oligomers precipitated by the refrigerant, and even in such an environment, a film without oligomer precipitation is required. -ing By the way, polyether ketone is known as a crystalline thermoplastic polymer that is tough and has excellent heat resistance (Japanese Patent Publication Nos.
No. 1-10486), studies and proposals for making this film have been made. For example, in JP-A-57-137116, development of polyetherketone in application fields utilizing heat resistance, that is, insulating films for motors, insulating films for transformers, insulating films for capacitors, flexible printed circuit boards, etc. As expected, a method for producing a uniaxially oriented film by rolling is described. Further, JP-A-61-37419 discloses that a biaxially oriented thermoplastic polyetherketone film is used in the field of electric parts such as capacitors, electric wire coatings and flexible printed circuit boards, and precision parts such as recording medium bases. It is described as suitable.

(Problems to be Solved by the Invention) Then, in place of the conventional biaxially oriented polyethylene terephthalate film of an electric insulating material, a conventionally known thermoplastic polyetherketone resin film is used, and an electric wire coating tape is produced. Although it was confirmed that the heat resistance was improved, it became clear that the heat deterioration resistance, the dielectric breakdown strength, the flatness, and the like had to be further improved.

An object of the present invention is to solve the problems of the prior art, and to provide a film for an electric insulating material which is excellent in heat resistance and electric insulation properties, and has a flat surface, but also excellent in 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, and the heat shrinkage ratio at 150 ° C. of the film is 3.0% or less, 280 Breaking elongation after heating at ℃ for 500 hours is 10% or more, refractive index in the thickness direction is 1.64
Hereinafter, a film for electric insulating material having an F-5 value of 11 kg / mm ² or more, and further, an electric insulation having a film surface roughness of 0.005 to 0.10 μm Achieved by material film.

The thermoplastic polyetherketone resin in the present invention is a constitutional unit. Alternatively, it is a polymer composed of this unit and another structural unit. As other structural units, for example, Etc. In the above structural unit, A is a direct bond, oxygen, —SO ₂ —, —CO— or a divalent lower aliphatic hydrocarbon group, and Q and Q ′ may be the same or different, CO- or -SO ₂ - and is, n represents 0 or 1
Is. These polymers are disclosed in Japanese Examined Patent Publication No. 60-32642,
It is described in JP-B-61-10486 and JP-A-57-137116.

Thermoplastic polyether ketone resins include polyarylene polyether, polysulfone, and
Resins such as polyarylate, polyester and polycarbonate may be blended, and stabilizers, antioxidants,
You may include additives, such as an ultraviolet absorber.

As mentioned above, the thermoplastic polyetherketone resin is known per se and can be produced by a method known per se.

The thermoplastic polyetherketone resin has an apparent melt viscosity of 380 ° C., an apparent shear rate of 1000 sec ⁻¹ , 500 poises to 10000 poises, and further 1000 poises to 5000 poises.
Those in the poise range are preferable from the viewpoint of film-forming property and film characteristics.

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 It is necessary that the elongation at break when heated at 280 ° C. for 500 hours is 10% or more, preferably 15% or more, more preferably 20% or more. Outside of this range, since the toughness is low, repeated bending in a high temperature environment causes cracking, which makes it unusable for use as a film for an electrical insulating material.

Furthermore, the electrically insulating material film of the present invention, the refractive index in the thickness direction of the film is 1.64 or less, preferably 1.62 or less,
More preferably, it is 1.61 or less, and the F-5 value is 11 kg / mm ²
Or more, preferably 12 kg / mm ² or more, more preferably 13 kg
/ mm ² or more is required.

According to the research conducted by the present inventors, conventionally, the heat deterioration resistance of a plastic film is the heat resistance of the polymer itself constituting the film, for example, heat decomposition resistance, oxidation decomposition resistance at high temperature,
Although it was supposed to be uniquely determined by hydrolysis resistance, etc., the surprising fact that the heat deterioration resistance of the thermoplastic polyetherketone resin film changes depending on the film forming conditions, that is, the fine structure of the film. It became clear. The difference in heat deterioration resistance between the biaxially oriented film having a refractive index in the thickness direction of 1.64 or less and the film having a refractive index of more than 1.64 is particularly remarkable in the breaking elongation after heating for a long time. That is, the biaxially oriented film having a refractive index of 1.64 or less in the thickness direction has a slight decrease in elongation at break after heating for a long time, whereas the biaxially oriented film having a refractive index of more than 1.64 is short. It is weakened by heating for a long time, so that the elongation at break is remarkably reduced, and the breakdown strength is remarkably reduced. Further, as for the F-5 value, as in the case of the above-mentioned refractive index, when it is less than 11 kg / mm ² , the brittleness at high temperature is remarkable, so that the failure elongation is significantly lowered, and further, The breakdown voltage also drops significantly.

Further, the surface roughness of the film of the present invention is 0.005 ~ 0.10μ
m, preferably 0.01 to 0.07 μm, more preferably 0.01
~ 0.05μm is desirable and surface roughness is 0.005μm
If it is less than the above range, good slipperiness is difficult to be obtained, wrinkles may occur during film winding, or blocking between films may occur, and workability in the processing step is deteriorated. On the other hand, when the surface roughness exceeds 0.10 μm, the workability is improved, but the dielectric breakdown voltage is lowered or its variation is increased.

The thermoplastic polyetherketone resin film of the present invention,
For example, a thermoplastic polyetherketone resin is melt extruded at a temperature of (Tm + 30) ° C. to (Tm + 90) ° C. (Tm is a melting point) to obtain an unstretched film, and the unstretched film is uniaxially (longitudinal or lateral) ( It is stretched at a temperature of Tg-10) to (Tg + 45) ° C (where Tg is the glass transition temperature of the polyetherketone resin) at a draw ratio of 1.5 times or more, particularly 2.5 times or more, and then in the direction perpendicular to the drawing direction (first step). If the stretching is in the machine direction, the second stage is in the transverse direction) to (Tg + 10) ~ (Tg
It can be produced by stretching at a temperature of +40) ° C. and a draw ratio of 2.5 to 5.0 times. In this case, the area draw ratio is preferably 4 times or more, more preferably 6 times or more. The stretching means may be simultaneous biaxial stretching or sequential biaxial stretching. Furthermore, the biaxially stretched film may be heat-set at a temperature of (Tg + 70) ° C. to Tm ° C. For example, a polyetheretherketone film is preferably heat set at 250 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 according to its application.

As means for adjusting the surface roughness of the film in the above range, substantially inactive solid particles in the thermoplastic polyetherketone resin are uniformly dispersed in the film, the particle size thereof,
The content may be adjusted. The inert solid particles may be externally added fine particles or internal fine particles, and may be, for example, a metal salt of an organic acid, an inorganic substance, a special resin, or the like. Preferred inert solid particles include calcium carbonate, silicon dioxide (including hydrates, diatomaceous earth, silica sand, quartz, etc.), alumina, and silicates containing 30% by weight or more of SiO ₂ (for example, amorphous). Quality or crystalline clay minerals, aluminosilicate compounds (including baked products and hydrates), asbestos, zircon,
Fly ash, etc.), oxides of Mg, Zn, Zr and Ti,
Ca and Ba sulfates, Li, Na and Ca phosphates (including monohydrogen and dihydrogen salts), Li, Na and K benzoates,
Ca, Ba, Zn and Mn terephthalate, Mg, Ca, Ba,
Zn, Cd, Pb, Sr, Mn, Fe, Co and Ni titanates, Ba
And Pb chromate, carbon (eg carbon black, graphite etc.), glass (eg glass powder, glass beads etc.), MgCO ₃ , fluorspar, ZnS and silicon resin. Preferred are anhydrous silicic acid, hydrous silicic acid, aluminum oxide, aluminum silicate (including calcined products and hydrates), 1 lithium phosphate, 3 lithium phosphate, sodium phosphate, calcium phosphate, barium sulfate, titanium oxide, Examples include lithium benzoate, double salts of these compounds (including hydrates), glass powder, viscosity (including kaolin, bentonite, clay, etc.), talc, diatomaceous earth, silicone resin and the like. The average particle size of these inert solid particles is usually 0.01 to 3 μm, preferably 0.05 to 2 μm, and more preferably 0.1 to 1.5 μm. Also, the content of these inert solid particles is usually
0.005 to 1% by weight based on the thermoplastic polyetherketone resin, but 0.01 to 1% by weight, and further 0.01 to 0.5% by weight
Is preferred.

Incidentally, among the above-mentioned inert solid particles, the average particle size is 0.05 to
Spherical silica fine particles having a particle size ratio of 4 μm and a particle diameter ratio (major axis / minor axis) of 1.0 to 1.2 are used alone or mixed with the above other inert solid particles so as to have a content of 0.01 to 3.0 wt%, When dispersed in a plastic polyetherketone resin, or with an average particle size of 0.01 to 4 μm, f = V / D ₃ (where V is the average volume (μm ³ ) of the particles, D is the average maximum particle size of the particles). (Μ
volume shape factor (f) defined by
π / 6, the general formula RxSiO _{2 -X / Z} (where R is 1 carbon atom)
A hydrocarbon group of ~ 7, x is 1-1.2), alone or mixed with the other inert solid particles mentioned above so that the content is 0.005 to 3.0% by weight,
When dispersed and contained in the thermoplastic polyetherketone resin, since the affinity between the spherical silica fine particles, the silicone resin fine particles and the polyetherketone resin is large, the frequency of occurrence of voids around the particles during biaxial orientation is high. It is particularly preferable since it can be formed in a small amount and has a good electric insulating property. In this case, for spherical silica fine particles,
It is preferably substantially spherical and has a sharp particle size distribution and is nearly monodisperse, and the manufacturing method thereof and the like are not particularly limited. Particularly, it is desirable that the relative standard deviation represented by the following formula is 0.5 or less.

Where Di: area circle equivalent diameter of each particle (μm): average area circle equivalent diameter (μm) n: represents the number of particles.

For example, spherical silica particles can be prepared from ethyl orthosilicate [Si (O
C ₂ H _{5) 4} hydrous silica from the hydrolysis of] [Si (OH) _4] make monodisperse spheres, further silica binding by dehydrating this hydrous silica monodispersed spheres [≡Si-O-Si≡] It can be manufactured by growing it three-dimensionally (Chemical Society of Japan 81, NO.9, P.1503).

Si (OC ₂ H ₅ ) ₄ + 4H ₂ O → Si (OH) ₄ + 4C ₂ H ₅ OH ≡Si-OH + HO-Si ≡ → ≡Si-O-Si ≡ + H ₂ O On the other hand, the silicone resin particles are substantially It is preferably spherical and has a sharp particle size distribution and is close to monodisperse, and is not limited to the production method or the like. In particular, the particle size distribution (γ) represented by the following formula is 1-1.
4 is desirable.

γ = D ₂₅ / D ₇₅ The spherical silicon resin fine particles have the following formula (A) R _X SiO _{2-X / Z} (A) It has a composition represented by.

R in the above formula (A) is a hydrocarbon group having 1 to 7 carbon atoms, and for example, an alkyl group having 1 to 7 carbon atoms, a phenyl group or a tolyl group is preferable. The alkyl group having 1 to 7 carbon atoms may be linear or branched, and for example,
Methyl, ethyl, n-propyl, iso-propyl, n-
Butyl, iso-butyl, tert-butyl, n-pentyl,
Examples thereof include n-heptyl and the like.

Of these, methyl and phenyl are preferable as R, and methyl is particularly preferable.

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

In the above formula (A), when x is 1, the above formula (A)
Can be represented by the following formula (A) -1 RSiO _1.5 (A) -1 [where R is the same as defined above].

The composition of the above formula (A) -1 has the following structural portion in the three-dimensional polymer chain structure of a silicone resin; It is derived from.

When x is 1.2 in the above formula (A), the above formula (A) is the following formula (A) -2 R _1.2 SiO _1.4 (A) -2 [wherein the definition of R is the same as above]. It can be represented by.

The composition of the above formula (A) -2 has the structure of the above (A) -1 0.8
It can be understood that it is composed of moles and 0.2 mole of a structure represented by the following formula (A) ′ R ₂ SiO ... (A) ′ [where R is defined as above].

The above formula (A) 'represents the following structural portion in the three-dimensional polymer chain of silicone resin; Derived from.

As understood from the above description, the composition of the above formula (A) substantially consists of, for example, only the above formula (A) -1 structure, or the composition of the above formula (A) -1 and the above formula (A) -1 A)-
It can be seen that the structure of No. 2 is composed of coexisting structures in a state where they are randomly bonded at an appropriate ratio.

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

The silicone resin fine particles have, for example, the following formula RSi (OR ′) ₃ The trialkoxysilane represented by or a partial hydrocondensate thereof can be produced by hydrolysis and condensation in the presence of ammonia or an amine such as methylamine, dimethylamine, ethylenediamine and the like with stirring. According to the above method using the above starting material, it is possible to produce silicon resin particles having the composition represented by the above formula (A) -1.

R ₂ Si (OR ′) ₂ According to the above method, the dialkoxysilane represented by the formula (A) is used together with the above trialkoxysilane.
It is possible to produce silicon resin particles having a composition represented by -2.

(Examples) Hereinafter, the present invention will be described in more detail with reference to Examples. Various physical properties and characteristics were measured by the following methods.

(1) Heat shrinkage rate A marked line is inserted at intervals of about 30 cm in the measurement sample, and heat treatment is performed in a heating oven in a tension-free state for a certain period of time (150 ° C x 30 minutes).
It was calculated from the following change from the sample length change.

In addition, measuring the heat shrinkage in the longitudinal direction and the lateral direction of the film,
The average value was used as the representative value.

(2) Thermal deterioration resistance After heating at 280 ° C for 500 hours in a tensionless state with a gear aging tester, the dielectric breakdown voltage and the breaking elongation are measured at room temperature.

a) Dielectric breakdown voltage Implemented in accordance with JIS C2318.

b) Elongation at break For samples cut to a width of 10 mm and a length of 150 mm, the chuck distance is 100 mm and the tensile speed is 10 mm / min and the chart speed is 50 mm.
Pull at room temperature with an Instron type universal tensile tester under the condition of / min. When the original length is lo and the length at break is fl, it is expressed as [(fl-lo) / lo] x 100%.

(3) Refractive index Measured with an Atsube refractometer at a light wavelength of 589 nm (center of D line of Na) at a temperature of 20 ° C.

(4) F-5 value Cut the film into a sample width of 10 mm and a length of 15 cm, and place it between the chucks.
The sample (film) was pulled with an Instron type universal tensile tester at room temperature under the conditions of 100 mm and a pulling speed of 100 / min and a chart speed of 500 mm / min. It was calculated by dividing the load by the initial cutting.

(5) Average particle size (DP) Shimadzu CP-50 Model Centrifugal Particle Size Analyzer
ser). From the integrated curve of the particles of each particle size calculated based on the obtained centrifugal sedimentation curve and its abundance,
The particle size corresponding to 50 mass% was read, and this value was taken as the average particle size (see "Particle size measurement technology", published by Nikkan Kogyo Shimbun, 1975, pp.242-247).

(6) Roughness of film surface (Ra) CLA (Center Line Average) JIS B06
It measured according to 01. Using a stylus type surface roughness meter (SURFCOM3B) made by Tokyo Seimitsu Co., Ltd., the radius of the needle is 2μ and the load is 0.0
A chart (film surface roughness curve) was drawn under the condition of 7 g. From the film surface roughness curve, a portion having a measurement length L is extracted in the direction of the center line, the center line of the extracted portion is taken as the X axis, and the direction of longitudinal magnification is taken as the Y axis.
When expressed by f (X), the value given by the following formula (Ra:
μm) is defined as the flatness of the film surface.

In the present invention, 8 pieces were measured with a reference length of 0.25 mm, and Ra was expressed as an average value of 5 pieces excluding 3 pieces having the larger values.

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

◯: Excellent in slipperiness, good workability and process passability.

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

X: Wrinkles are formed in the winding process or the end faces are uneven, and the process passability is poor.

(8) Comprehensive Evaluation Heat resistance, mechanical and electrical characteristics, and workability were comprehensively evaluated, and in all cases, extremely good ones were marked with ⊚, good ones were marked with ◯, and bad ones were marked with x.

Examples 1 to 10 Comparative Examples 1 to 4 Inert particles shown in Table 1 were mixed with thermoplastic polyether ketone (made by ICI: polyether ketone 380G) at a ratio shown in Table 1, and after blending, an extruder was used. To extrude at 380 ℃ and cast it onto a casting drum kept at a temperature of 80 ℃ to make an unstretched film.
Then, the film was biaxially stretched at the stretching ratios in the machine direction and the transverse direction shown in Table 1, and further heat-set at the temperature shown in Table 1 for 30 seconds to obtain a biaxially oriented film having a thickness of 25 μm. The characteristics of the obtained film were as shown in Table 1.

As is clear from the above results, it is understood that the biaxially oriented films of the present invention (Examples 1 to 10) are all excellent in heat resistance, mechanical and electrical characteristics, and workability.

(Effects of the Invention) As described in detail above, the film for an electrical insulating material of the present invention is excellent in heat resistance, mechanical properties, electrical characteristics, and handling workability, and is useful for motors, transformers, capacitors, electric wires, cables, and communications. It can be suitably used for electric parts such as devices, flexible printed circuits, and substrates for liquid crystal panels.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideo Kato 3-37-19 Koyama, Sagamihara City, Kanagawa Prefecture, Teijin Limited Plastic Research Laboratory (56) Reference JP-A-61-64003 (JP, A) JP 61-138626 (JP, A)

Claims (2)

[Claims] 1. A film made of a biaxially oriented thermoplastic polyetherketone resin, which has a heat shrinkage ratio of not more than 3.0% at 150 ° C. and a breaking elongation of 10% after being heated at 280 ° C. for 500 hours. As described above, the film for electric insulating material has 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. The film for electrical insulating material according to claim 1, wherein the surface roughness of the film is 0.005 to 0.10 μm.