JPH0725151B2 - Laminated film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a laminated film.

[Prior Art] As a conventional film, (1) use of a biaxially oriented poly-p-phenylene sulfide film as an electrically insulating material is known from JP-A-55-35459. It is also known to use the (2) tetrafluoroethylene / hexafluoropropylene copolymer film for the same purpose.

Further, as the laminated film, (3) tetrafluoroethylene
A film obtained by laminating a polyimide film on a propylene hexafluoride copolymer film is known from Japanese Patent Publication No. 12900/1974.

[Problems to be Solved by the Invention] However, the conventional film has the following problems.

The film of the item (1) lacks impact resistance, and when it is used as a slot liner or a wedge of a motor, for example, it is likely to be peeled (delamination) into two or more layers or torn inside the film.

The item (2) film has a weak rigidity, and when it is used as a slot liner or a wedge of a motor, for example, it is difficult to insert it into the gap between the field core and the winding. In addition, it lacks moldability, and it is difficult to mold it into a desired shape as an insulating material.

The film of item (3) is vulnerable to alkalis and alkali metal salts (for example, snow melting agents sprayed on roads), and is used as an insulating material in the presence of these chemicals (for example, snow melting agents are sprayed). There was a restriction on the electrical insulation material for the electrical equipment of automobiles running on the road.

An object of the present invention is to solve such problems and provide a film having impact resistance, waist strength, moldability, and alkali resistance.

[Means for Solving the Problems] In the present invention, (1) biaxially oriented poly-p-polymer is formed on at least one surface of a tetrafluoroethylene / hexafluoropropylene copolymer film.
A laminated film characterized in that a phenylene sulfide film is joined without an adhesive.

The present invention also provides (2) the laminated film as described in the above item (1), in which biaxially oriented poly-p-phenylene sulfide films are bonded to both surfaces of a tetrafluoroethylene / hexafluoropropylene copolymer film. In this case, one biaxially oriented poly-p-phenylene sulfide film has a thickness A, the other biaxially oriented poly-p-phenylene sulfide film has a thickness A ', and a tetrafluoroethylene / hexafluoropropylene copolymer weight. It is characterized in that the thickness B of the united film satisfies 2 ≦ (A + A ′) / B ≦ 20.

In the present invention, a biaxially oriented poly-p-phenylene sulfide film (hereinafter sometimes abbreviated as PPS-BO)
Means that a resin composition containing poly-p-phenylene sulfide as a main component is melt-molded into a sheet shape and biaxially stretched,
It is a film formed by heat treatment.

The degree of orientation of the film was determined by wide-angle X-ray diffraction with respect to the crystal peak at 2θ = 20 to 21 degrees.
It is preferably 0.07 to 0.50 in the e direction and 0.60 to 1.00 in the Through direction.

Further, the thickness of the film is preferably in the range of 10 to 200 microns.

Here, the resin composition containing poly-p-phenylene sulfide as a main component (hereinafter, may be abbreviated as PPS-based composition) means 90% by weight of poly-p-phenylene sulfide.
A composition containing the above.

When the content of PPS is less than 90% by weight, the crystallinity of the composition, the heat transition temperature, etc. are lowered, and the heat resistance, dimensional stability, mechanical properties, etc., which are the characteristics of the film made of the composition, are impaired. .

The remaining less than 10% by weight in the composition may contain a polymer other than PPS, an inorganic or organic filler, a lubricant, a colorant, an ultraviolet absorber, etc., within the range not impairing the object of the present invention. Absent.

The melt viscosity of the resin composition is 300 ° C. at a shear rate of 200.
Under the condition of 1 / sec, a range of 500 to 12000 poise is preferable from the viewpoint of film moldability.

The melt viscosity of the resin composition is equal to the melt viscosity of the biaxially oriented poly-p-phenylene sulfide film finally obtained.

Here, poly-p-phenylene sulfide (hereinafter sometimes abbreviated as PPS) means that 70 mol% or more (preferably 85 mol% or more) of the repeating unit has a structural formula. A polymer comprising a structural unit represented by Related ingredients
If it is less than 70 mol%, the crystallinity of the polymer, the heat transition temperature, etc. are lowered, and the heat resistance, dimensional stability, mechanical properties, etc., which are the features of the film made of the resin composition containing PPS as a main component, are impaired.

If the repeating unit is less than 30 mol%, preferably less than 15 mol%, a unit containing a copolymerizable sulfide bond may be contained.

In the present invention, a tetrafluoroethylene / hexafluoropropylene copolymer film (hereinafter sometimes abbreviated as FEP film) means a resin containing at least 90% by weight of a tetrafluoroethylene / hexafluoropropylene copolymer. It refers to a product obtained by molding the composition into a sheet.

The thickness of the film is preferably in the range of 10 to 200 microns.

Here, the tetrafluoroethylene / hexafluoropropylene copolymer is a copolymer of tetrafluoroethylene (hereinafter sometimes referred to as 4F) and hexafluoropropylene (hereinafter sometimes referred to as 6F). A polymerized polymer having a 6F content of 15 to 25 mol% is preferable from the viewpoint of impact resistance and film formability.

The present invention is a PPS-BO and FEP film, which are laminated without interposing an adhesive, the presence or absence of an adhesive layer, after dying the cross section of the laminated film with osmic acid, observed with an electron microscope, It can be examined whether or not an osmotic acid dyeable layer having a size of more than 0.1 micron is observed between the PPS-BO layer and the FEP film layer. When a PPS-BO or / and FEP film surface is subjected to physical or chemical treatment such as corona treatment, glow discharge treatment, plasma polymerization treatment, etc., it is extremely thin osmic of 0.1 micron or less at the lamination interface. Although acid dyeable layers are sometimes observed, they are not considered adhesives, and it goes without saying that such laminated films are also within the scope of the invention. PPS-B
When O and FEP film are bonded with an adhesive, the heat resistance is impaired, and the impact resistance varies greatly depending on how the adhesive cures.Furthermore, organic solvents such as refrigerator motor insulators are used. If they are used in contact with each other, the adhesive may dissolve and the film may peel off, which is not preferable.

The first aspect of the present invention has a two-layer structure in which PPS-BO (A) and FEP film (B) are laminated, but the thickness ratio A / B of A and B is 1 to 10. The range is preferable in terms of the balance between impact resistance and waist strength. Further, the thickness of the entire laminated film is preferably in the range of 20 to 300 μm in view of workability such as bending and winding.

The second embodiment of the present invention has a three-layer structure in which PPS-BO (A), FEP film (B), and PPS-BO (A ') are laminated in this order. A, B, A It is preferable that the thickness of ′ satisfies the formula 2 ≦ (A + A ′) / B ≦ 20 in terms of the balance between impact resistance and waist strength. Further, it is preferable that the thickness ratio A / A 'of A and A'is in the range of 0.5 to 2.0 in terms of isotropic property during bending and flatness (curl). Further, the thickness of the whole laminated film is preferably in the range of 30 to 500 μm in view of workability such as bending and winding.

Next, a method for producing the laminated film of the present invention will be described.

The PPS used in the present invention can be obtained by reacting alkali sulfide and paradihalobenzene in a polar solvent at high temperature and pressure.
In particular, sodium sulfide and paradichlorobenzene are preferably reacted in an amide-based high-boiling polar solvent such as N-methylpyrrolidone. In this case, in order to adjust the degree of polymerization, it is most preferable to add a so-called polymerization aid such as caustic alkali or alkali metal carboxylic acid and react at 230 to 280 ° C. The pressure in the polymerization system and the polymerization time are appropriately determined depending on the kind and amount of the auxiliary agent used, the desired degree of polymerization, and the like. The obtained powdery or granular polymer is washed with water and / or a solvent to separate a by-product salt, a polymerization aid, an unreacted monomer and the like.

In order to form this polymer into a biaxially oriented film, the resin melted by an extruder is cast quantitatively from a die onto a metal drum and rapidly cooled to obtain a non-oriented, amorphous sheet. Then, the sheet is biaxially stretched and heat treated by a known method. Stretching is 90 in both longitudinal and width directions
Perform at 3.0 to 4.5 times at ~ 110 ℃. Heat treatment is 240 ℃
~ 1 within the range of melting point, with constant length or 15% or less
Do it for ~ 60 seconds. In addition, it may be relaxed in one or two directions to improve the thermal dimensional stability of the film.

Production of the FEP film used in the present invention, FEP 380 ℃ ~ 420
It is possible to use a well-known method in which the film is melt-extruded at ℃ and cast on a cooling drum, or a commercially available film is used.

As mentioned above, FEP is a copolymer of 4F and 6F, but both 4F and 6F are fluoro (chloro) methane (CHClF ₂ )
Can be obtained by thermal decomposition of. Polymerization is for example (N
H ₄ ) ₂ S ₂ O ₈ as polymerization initiator, mixed gas of 4F 75% and 6F 25% was polymerized in water while maintaining at 45.7kgf / cm ² and 95 ° C, and further heated in air at 350 ° C for 3hr. Then, the crystal melting point is 28
A white polymer having a 6F content of about 16% at 0 ° C. is obtained.

Next, in order to laminate the PPS-BO and the FEP film, a method of press-bonding both under high temperature and high pressure can be used. In this case, the temperature is preferably 200 to 270 ° C. and the pressure is preferably 5 to 50 kg / cm ² .

For reliable crimping, both PPS-BO and FEP film
It is desirable that the pressure-bonded surface be corona treated beforehand. For FEP films, corona treatment in an organic solvent gas such as acetone or glow discharge treatment in ammonia gas is effective.

Industrially, the method of stacking PPS-BO and FEP films and passing them through a heated press roll is efficient.

In the case of three-layer lamination, the PPS-BO and FEP film may be laminated and then another layer of PPS-BO may be laminated, or three layers may be laminated and pressure-bonded simultaneously.

[Use] The film of the present invention thus obtained can be used as a general heat-resistant insulating material, but is particularly required to have a high level of balance of heat resistance, alkali resistance, impact resistance and waist strength. Suitable for motor slot liners and wedges. Further, it is suitable as an insulating material for electric equipment for automobiles, an insulating material for refrigerator motors, and the like. Further, various base materials such as a metal plate and other kinds of films may be laminated on the FEP film surface of the two-layer laminate of the present invention, or a resin such as paint or adhesive may be coated.

[Measurement Method] Next, the method of measuring and evaluating the characteristics used in the description of the present invention will be described.

(1) Heat resistance The tensile strength of the sample film at the initial stage and after aging at 180 ° C for 3000 hours in a hot air oven was measured according to the ASTM D638-72 method, and the strength after aging was 70% or more of the initial value. , 10 to less than 70% was rated as △, and less than 10% was rated as x.

(2) Waist strength and impact resistance In order to evaluate the waist strength and impact resistance required when inserting the wedge, which is the insulating member of the motor, between the stator core and the coil, the following method is used. Using.

That is, a sample film is cut into a rectangle having a width of 10 mm and a length of 50 mm, which is folded in two in the width direction, and a load of 10 kg is applied for 10 seconds to make a crease. Next, the sample is apex angle 90
゜, a 50 mm long groove block (made of SUS304) having a V-shaped cross section with a depth of 10 mm and a chevron block that fits perfectly with this block, sandwiching a length of 25 mm, both blocks 2 kg
Press with heavy force. The block in this state was fixed with the side from which the sample protruded facing upward, and a weight of 1 kg was dropped from a height of 10 cm from the tip of the sample and ranked according to the following.

Waist strength ○: Projection of the sample from the block is less than 5 mm (good waist strength) △: Same as above 5 mm and less than 20 mm ×: Same as above 20 mm (waist strength is not possible) Impact resistance ○: Sample is completely damaged No: △: Part of the tip was torn ×: Sample was severely torn (3) Alkali resistance After dipping the sample film in a 10 wt% sodium hydroxide aqueous solution at 25 ° C for 120 hours, ASTM If the tensile strength measured according to D638-72 is 70% or more of the value before immersion, ○ (good alkali resistance), 10 to less than 70% △, 10%
The value less than was defined as × (insufficient alkali resistance).

[Examples] Next, examples of the present invention will be described in more detail.

Example 1 (1) Preparation of Biaxially Oriented PPS Film Used in the Present Invention In an autoclave, 32.6 kg of sodium sulfide (250 mol,
(Including 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 sometimes referred to as NMP) 79.2 kg
Was charged and dehydrated at 205 ° C., then 37.5 kg (255 mol) of 1,4 dichlorobenzene (abbreviated as p-DCB), and NMP20.
0 kg was added, and the mixture was reacted at 265 ° C for 4 hours. The reaction product is washed with water and dried to give 100 parts of p-phenylene sulfide unit.
21.1 kg (yield 78%) of poly-p-phenylene sulfide having a melt viscosity of 3100 poise was obtained.

To this composition, 0.1 wt. Of fine silica powder with an average particle size of 0.7 μm
%, Calcium stearate 0.05% by weight, melted at 310 ° C. with a 40 mm diameter extruder, filtered with a 95% cut hole diameter 10 μm film using metal fiber, and then a linear lip with a length of 400 mm and a gap of 1.5 mm is formed. It was extruded from the T-die and cast on a metal drum whose surface was kept at 25 ° C. to be cooled and solidified to obtain an unstretched film having a thickness of 2 mm.

This film is stretched by a machine comprising a group of rolls,
Film temperature 98 ℃, stretching speed 30,000% / min longitudinal stretching 3.9 times, then using a tenter, temperature 100 ℃, stretching speed 1000
The film is laterally stretched 3.5% at a rate of 0.1% / min, and further heat-treated at 275 ° C for 10 seconds in the subsequent heat treatment chamber in the same tenter to give a thickness of 125 μm.
A biaxially oriented PPS film of was obtained (referred to as film A-1).

(2) FEP film used in the present invention Commercially available FEP film having a thickness of 50 μm (manufactured by Dupont, USA),
"TEFLON" FEP film C20 type) (referred to as film B-1) was used.

(3) Preparation of laminated film The film A-1 and the film B-1 are superposed and subjected to a heating press roll at a temperature of 250 ° C. and a surface pressure of 20 kg / cm ² to obtain PPS.
-Two-layer laminated film laminated film of BO and FEP film-
Got 1.

(4) Evaluation Table 1 shows the evaluation results of the obtained film. For comparison, film A-1, film B-1, film B-
A film obtained by laminating three sheets under the condition (3) (hereinafter referred to as film B-2) and a commercially available laminated film obtained by laminating a FEP film having a thickness of 25 μm on a polyimide film having a thickness of 125 μm (“Dupont Co., Ltd., USA”) KAPTON "600F051,
This is also referred to as film F) and four types of films were similarly evaluated, and the results are shown in Table 1. From Table 1, it can be seen that the laminated film of the present invention is an excellent laminated film having heat resistance, impact resistance, waist strength, and alkali resistance.

Example 2 PPS-BO having a thickness of 100 μm was formed into a film in the same manner as in Example 1 (referred to as film A-2). The above-mentioned FEP film (film B-1) was sandwiched between the two films and passed through a heating roll under the same conditions as in Example 1 to obtain a three-layer laminated film (referred to as laminated film 2).

When this film was evaluated, it was as follows, and it was found that it was an extremely excellent laminated film.

Heat resistance: ○ Impact resistance: ○ Waist strength: ○ Alkali resistance: ○ Example 3 In the same manner as in Example 2, various three-layer laminated films having the thickness constitution of each layer as shown in Table 2 were obtained. It was The evaluation results of those films are shown in Table 2.

From Table 2, the thickness of the outer PPS-BO is A, A ', the central FEP
When the thickness of the film is B, the formula 2 ≦ (A + A ′) / B
It can be seen that those satisfying ≦ 20 are more excellent.

Comparative Example Casting was performed in the same manner as in Example 1 to obtain an unstretched PPS film having a thickness of 125 μm. This film and thickness 50μm
FEP film (Film B-1) was laminated in the same manner as in Example 1 to give a two-layer laminated film (laminated film-9).
And The evaluation results of the obtained laminated film-9 are as follows and were inferior to the laminated film of the present invention.

Impact resistance: × Waist strength: △ Heat resistance: △ Alkali resistance: ○ [Effect of the invention] As a result of having the above-mentioned constitution, the laminated film of the present invention is an important characteristic as an electrical insulating material. It has heat resistance, impact resistance, waist strength, and alkali resistance, and it has become possible to use it in a wider range than previously possible with conventional films.

Claims (2)

[Claims] 1. A laminate characterized in that a biaxially oriented poly-p-phenylene sulfide film is bonded to at least one surface of a tetrafluoroethylene / hexafluoropropylene copolymer film without interposing an adhesive. the film. 2. When biaxially oriented poly-p-phenylene sulfide films are bonded to both surfaces of a tetrafluoroethylene / hexafluoropropylene copolymer film, one biaxially oriented poly-p-phenylene film is formed. The thickness A of the sulfide film, the thickness A ′ of the other biaxially oriented poly-p-phenylene sulfide film, and the thickness B of the tetrafluoroethylene / hexafluoropropylene copolymer film are 2 ≦ (A + A ′) / B ≦ 20. The laminated film according to claim (1), characterized in that: