JP2817254B2 - Laminate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a laminate. More specifically, the present invention relates to a laminate comprising an unstretched sheet of polyphenylene sulfide and a fiber sheet of an aromatic polymer having no melting point.

[Prior art] As electrical equipment and automobile parts become smaller and more efficient, heat resistance (especially long-term heat resistance at high temperatures), electrical properties, mechanical properties (especially impact resistance), flame retardancy, etc. There is an increasing demand for an electrical insulating material which is excellent in various properties and has a good balance, and is further excellent in impregnating properties of an insulating resin.

Conventionally, as an electric insulating material in this field, (1) use of a biaxially oriented polyphenylene sulfide film (hereinafter, may be abbreviated as PPS-BO) is disclosed in JP-A-55-3545.
It is known from Japanese Patent No. 9 and the like. (2) Unstretched polyphenylene sulfide sheets are also disclosed in JP-A-56-34426 and JP-A-57-1.
This is known from, for example, Japanese Patent Publication No. 21052. It is also known that (3) an aromatic polyamide fiber sheet is used.

On the other hand, as the laminated film, (4) a laminated film of PPS-BO and a biaxially stretched polyester film (JP-A-62
-292431) is also known. Examples of the laminate in this field include (5) a laminate of a fiber sheet of polyphenylene sulfide and PPS-BO (JP-A-63-237949).
(6) Laminate of aromatic polyamide fiber sheet and biaxially stretched polyester film, (7) Laminate of aromatic polyamide fiber sheet and PPS-BO (JP-A-60-63158)
Are also known.

[Problems to be Solved by the Invention] However, the above-mentioned films, laminated films, and laminates have the following problems.

The film of item (1) has poor impact resistance and tear strength. For example, when used as a slot liner or wedge of a motor, the film may be torn or delaminated. In the case where the insulating resin is impregnated, the impregnating property is poor.

The unstretched sheet of item (2) is rich in tear strength, but when exposed to a high temperature, the mechanical strength sharply decreases, and it is difficult to use the sheet alone as an electrical insulating material.

The fiber sheet of the item (3) has higher heat resistance, higher impact resistance and resin impregnation than the PPS-BO of the item (1).
Low electrical insulation (withstand voltage). In order to maintain the withstand voltage, it is necessary to increase the thickness of the fiber sheet, and it is difficult to reduce the size of the motor or the like.

In the laminated film of the item (4), the heat resistance, chemical resistance and wet heat resistance of the biaxially stretched polyester film of the central layer are poor, so that the use of the laminated film is limited.

The laminate of item (5) is rich in impact resistance and resin impregnation, but the heat resistance of the PPS fiber sheet is low.

The laminate of the item (6) has the same problems as the laminated film of the item (4).

The laminate of item (7) is obtained by laminating an aromatic polyamide fiber sheet and PPS-BO via an adhesive, but when the thickness of PPS-BO is increased, an impact force is applied. Occasionally, PPS-BO caused delamination.
Further, since an adhesive is used, heat resistance is poor or chemical resistance is poor depending on the adhesive used. For example, when rapid heat is applied to the laminate,
The adhesive is softened and partially peeled off due to the heat shrinkage of the PPS-BO and the dimensional change of the aromatic polyamide fiber sheet (the fiber sheet has high hygroscopicity and rapidly dehumidifies and shrinks at high temperatures). was there. In addition, it is difficult to manufacture the above-mentioned laminate by a method such as heat fusion without using an adhesive, because the adhesiveness is poor.

The present invention solves the above-mentioned problems, and has a good balance of properties such as heat resistance, electric insulation, chemical resistance, flame retardancy, impact resistance, and moisture and heat resistance without interposing an adhesive, and especially for a long time. An object of the present invention is to provide a laminate excellent in heat resistance, impact resistance and impregnation of an insulating resin.

[Means for Solving the Problems] The present invention relates to a laminate in which a fiber sheet made of an aromatic polymer having no melting point is laminated on at least one surface of an unstretched polyphenylene sulfide sheet without using an adhesive. It is about.

In the present invention, polyphenylene sulfide (hereinafter referred to as PP)
S may be abbreviated as S) when 70 mol% or more (preferably 85 mol% or more) of the repeating unit has a structural formula Means a polymer comprising the structural unit represented by Such components
If it is less than 70 mol%, the crystallinity and heat transition temperature of the polymer will be low, and the heat resistance, dimensional stability, mechanical properties, etc., which are characteristics of a film composed of a resin composition containing PPS as a main component, will be impaired.

If the amount of the repeating unit is less than 30 mol%, preferably less than 15 mol%, a unit containing a copolymerizable sulfide bond may be contained. The method of copolymerizing the polymer may be random or block.

In the present invention, a resin composition containing polyphenylene sulfide as a main component (hereinafter sometimes abbreviated as a PPS-based composition) refers to a composition containing 60% by weight or more of polyphenylene sulfide.

When the content of PPS is less than 60% by weight, mechanical properties such as tear strength, heat resistance and the like of an unstretched sheet made of the composition are impaired.

The remaining less than 40% by weight of the composition may contain additives other than PPS, such as polymers, inorganic or organic fillers, lubricants, colorants and the like.

The melt viscosity of the resin composition is as follows: temperature 300 ° C., shear rate 200
Under sec ⁻¹ , the range of 700 to 20,000 poise is preferable from the viewpoint of sheet formability.

The unstretched sheet (hereinafter may be abbreviated as PPS-NO) according to the present invention is a general term for a film, a sheet, and a plate having a thickness of 1 mm or less obtained by melt-molding the PPS-based composition. It refers to a substantially non-oriented one.

The aromatic polymer having no melting point in the present invention,
This means that the decomposition point of the main component constituting the polymer is lower than its theoretical melting point. Needless to say, it is not possible to form the polymer in a molten state, that is, to form a fiber by melt spinning. 1. Aromatic polyamide (1) Polymer obtained by condensation of aromatic dicarboxylic acid and aromatic diamine, for example, obtained by condensing isophthalic chloride and metaphenylenediamine in a polar solvent Polymetaphenylene isophthalamide (2) Polymer obtained by condensing aromatic aminocarboxylic acid (3) Copolymer of (1) and (2) 2. Aromatic polyamideimide 3. Aromatic polyimide 4. Aroma Aromatic polyamide imides, aromatic polyamide imidazoles, aromatic polyamide hydrazides, and the like, with aromatic polyamides being most preferred.

The fiber sheet in the present invention is a thin sheet composed of an aggregate of the polymer fibers, and is usually paper,
It is a general term for what is called nonwoven fabric, woven fabric, felt, etc.

The thickness of the fiber sheet is preferably 10 to 500 μm, the thickness of the constituent fibers is 100 μm or less, and the basis weight is 2 to 600 g /
m ² (more preferably 5 to 150 g / m ² ) is preferred.

Further, it does not matter at all that the fiber sheet contains a small amount of material other than the fiber such as an adhesive for the purpose of binding the fibers together.

The laminate of the present invention is obtained by laminating the above-mentioned fiber sheet on at least one surface of PPS-NO without using an adhesive. When the adhesive is interposed, a decrease in the heat resistance and chemical resistance of the adhesive lowers the properties of the laminate. In particular, when cracks occur in the adhesive layer due to thermal deterioration of the adhesive, the heat resistance life of the electrical and mechanical properties is reduced. In addition, there is also a problem that the film and the fiber sheet are peeled off due to the softening of the adhesive when suddenly exposed to a high temperature.

Further, the PPS-NO used for the laminate of the present invention, which has been subjected to surface treatment such as corona treatment and plasma treatment, is also included in the present invention.

The thickness configuration of the laminate of the present invention is such that the thickness of the PPS-NO is [A], the thickness of the aromatic polymer fiber sheet is [B],
In the case of [B ′], the two-layer laminate (fiber sheet / PPS-NO), which is the first embodiment of the laminate structure of the present invention, preferably has a range of 0.05 ≦ A / B ≦ 2. When the thickness ratio is less than 0.05, the withstand voltage is low, and when it exceeds 2, the heat resistance is reduced. Further, a three-layer laminate (fiber sheet) which is the second embodiment of the laminate structure
/ PPS-NO / fiber sheet) is preferably in the range of 0.05 ≦ A / (B + B ′) ≦ 5. If the above thickness ratio is less than 0.05, the withstand voltage is low, and if it exceeds 5, the heat resistance decreases.
B / B 'is preferably in the range of 0.5 to 2 from the viewpoint of workability during processing.

Further, in the above two laminated structures, a three-layer laminated body is particularly preferable in terms of long-term heat resistance at a high temperature, impregnation with an insulating resin, and the like.

Furthermore, the thickness of the entire laminate is preferably in the range of 20 to 2000 μm (more preferably, 30 to 1000 μm).

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

The PPS used in the present invention is obtained by reacting alkali sulfide and paradihalobenzene in a polar solvent under high temperature and high pressure. In particular, sodium sulfide and paradichlorobenzene
The reaction is preferably carried out in an amide high boiling point polar solvent such as -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 a caustic alkali or an alkali metal carboxylate and react at 230 to 280 ° C. The pressure and polymerization time in the polymerization system are appropriately determined depending on the type 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, unreacted monomers and the like.

In order to form this polymer into an unstretched sheet, it is supplied to a melt extruder represented by an extruder, heated to a temperature equal to or higher than the melting point of the polymer, melted, continuously extruded from a slit-shaped die, and formed into a film. By rapidly cooling to a temperature below the glass transition point, a non-oriented sheet is obtained.

Next, a method for producing the fiber sheet used in the present invention will be described. First, the above-mentioned aromatic polymer is spun by a method such as a dry spinning method or a wet spinning method, and if necessary, subjected to stretching, heat treatment, or the like to obtain fibers of the polymer.

As a method for obtaining a fiber sheet from the fibers thus obtained, a dry method or a wet method can be used.

Examples of the dry method include a method using a normal shrinking machine, a needle punch method, a spun bond method, a method for opening a long fiber sheet, and a method for converting short fibers into a fiber sheet using an adhesive. In the wet method, a fiber or a fiber dispersed in water is bonded to the fiber sheet using heat or an adhesive or the like using a normal paper machine or the like. Depending on the purpose of use, the porosity may be changed by calendering the fiber sheet.

The most preferred aromatic polyamide-based paper as the fiber sheet is polymethphenylene isophthalamide obtained by polymerizing metaphenylenediamine and isophthalic acid chloride in a polar solvent, into a short fiber by a dry spinning method, and wet-processed to form a paper. And then, if necessary, heat calendering for the purpose of improving mechanical properties and electrical insulation.

Next, in the method of laminating the PPS-NO and the fiber sheet of the aromatic polymer, the following method can be used for the two-layer laminate of the present invention.

(1) Laminate PPS-NO and fiber sheet and set temperature to 250
Lamination is performed by thermocompression bonding at a temperature of 300 ° C. and a pressure of 1.0 to 20 kg / cm ^{2 by} a method such as a roll press method or a hot plate press method.

(2) PPS is melt-extruded directly on the fiber sheet and laminated. In this case, the PPS is supplied to an extruder, heated to a temperature equal to or higher than the melting point, continuously extruded from a slit die, and laminated while being pressed onto a fiber sheet on a press roll provided below. Further, it is preferable from the viewpoint of adhesiveness to perform thermocompression bonding under the conditions of the above item (1) during or after the lamination.

Next, when laminating into three layers, (3) a fiber sheet, PPS-NO, and a fiber sheet are superimposed in this order and thermocompression-bonded under the conditions of the above item (1).

(4) Between the two layers of fiber sheets under the conditions of the above (2)
Extrude and laminate PPS.

(5) PPS-N of the two-layer laminate obtained in (1) or (2)
Another fiber sheet is laminated on the O side by thermocompression bonding under the condition of (1).

Such a method can be used.

[Effect of the Invention] Since the laminate of the present invention has the above-described structure, heat resistance (long-term heat resistance, high-temperature short-term heat resistance), impact resistance, wet heat resistance, flame resistance, which are important properties particularly as an electrical insulating material, It became a material with various properties such as resin impregnating property balanced at a high level.
In particular, it has excellent heat resistance and impact resistance.

Further, since the laminate of the present invention does not include an adhesive, deterioration of the adhesive does not lower the characteristics of the laminate.

[Uses] The laminate of the present invention is most suitable for insulating materials such as motors and transformers that require heat resistance and impact resistance. For example, it can be used for an alternator, a starter motor, an axle motor, a servomotor, and the like for an automobile.

Further, since it has excellent impregnation with an insulating resin, it is also suitable for a mold transformer or a motor requiring resin impregnation.
Furthermore, since it has excellent radiation resistance and low-temperature characteristics, it is most suitable for an electrical insulating material of a device requiring radiation resistance such as a nuclear power plant.

Further, the laminate of the present invention may be bonded to another film or metal, or may be coated with another resin.

[Characteristic Evaluation Method] Next, the characteristic evaluation method and evaluation criteria used in the description of the present invention will be described.

(1) Long-term heat resistance The tensile strength of the sample at the initial stage and after aging for 1000 hours at a predetermined temperature in a hot-air oven is determined by ASTM-D-638-73.
Measured according to the method, the strength after aging is 70% of the initial value
Heat resistance: ◎, 50% to less than 70% ○, 10
Less than 50% was rated as Δ, and less than 10% was rated as ×.

(2) High-temperature short-term heat resistance The sample was placed in a hot-air oven at 280 ° C for 1 minute, and the flatness, molten state, and peeled state were observed according to the following criteria.

：: No deterioration in flatness, no melting, no peeling.

Δ: The flatness is slightly deteriorated or partially melted and partially peeled.

X: Deterioration of flatness, severe melting and peeling.

(3) Tear strength Measured according to JIS-P8116-1960 and expressed in g / mm.

(4) Impact resistance A sample is cut out to a width of 20 mm and a length of 100 mm, formed into a loop shape in the length direction, and fixed at the end to be 20 mm from the end in the width direction of the sample.
From a height of cm, a weight weighing 1 kg was dropped and ranked according to the following.

：: The sample is not damaged at all.

Δ: The tip is partially torn.

×: The tip is largely delaminated or severely torn.

(5) Dielectric breakdown strength According to ASTM-D-149.

(6) Resin impregnating property The following epoxy resin is vacuum impregnated, and the adhesion with the epoxy resin is observed. ○: No peeling at all; X.

 “Epicoat” 828 (manufactured by Shell) The resin was cured at 160 ° C. for 5 hours.

EXAMPLES Next, the present invention will be described in detail with reference to examples.

Example 1 (1) Preparation of unstretched PPS sheet used in the present invention In an autoclave, sodium sulfide 32.6 kg (250 mol, containing 40 wt% of crystallization water), sodium hydroxide 100 g, sodium benzoate 36.1 kg (250 mol), And N-methyl-2-pyrrolidone (hereinafter sometimes abbreviated as NMP) 79.
2kg is charged and dehydrated at 205 ° C. Then, 37.5kg (255 mol) of 1.4 dichlorobenzene and 20.0kg of NMP are added, and 265 ° C is added.
For 4 hours. The reaction product is washed with water, dried and p
-Consisting of 100 mol% of phenylene sulfide units,
Poly-p-phenylene sulfide having a melt viscosity of 3100 poise
21.1 kg (78% yield) were obtained.

Into this composition, a silica fine powder having an average particle size of 0.7 μm was added.
wt%, calcium stearate 0.05wt%, 40mm
Melted at 310 ° C with an extruder with a diameter of 95%, filtered through a 95% cut hole diameter 10μm filter using metal fibers, and then extruded from a T-die having a linear lip with a length of 400mm and a gap of 0.5mm, and the surface was heated to 25 ° C. It was cast on a metal drum kept and an unstretched sheet having a thickness of 150 μm was obtained (referred to as sheet-1).

(2) Preparation of aromatic polyamide fiber sheet Polymetaphenylene isophthalamide obtained by solution polymerization in a polar solvent using metaphenylenediamine and isophthalic chloride as raw materials is converted into short fibers by dry spinning. Subsequently, after dispersing the short fibers in water, papermaking was performed to obtain a fiber sheet. The fiber sheet has a basis weight of 20 g / m ² (thickness of 50 μm).
m).

(3) Preparation of Laminate The PPS-NO and aromatic polyamide fiber sheet obtained above were laminated in the order of fiber sheet / PPS-NO / fiber sheet, and the temperature was 280 ° C, the pressure was 10 kg / cm ² , and the speed was 1 m / min. Roll pressing was performed under the following conditions. The obtained laminate had good flatness and a tensile strength of 21 kg / mm ² . (Laminate-1) Comparative Examples 1 to 6 (1) The following epoxy adhesive was applied to one surface of the aromatic polyamide fiber sheet used in Example 1, and the fiber sheet / PPS was used as in Example 1. A three-layer laminate of -NO / fiber sheet was prepared. (Laminate-2, Comparative Example 1) The coating conditions were a gravure roll method with a coating thickness of 10 μm,
The drying condition of the solvent was 100 ° C. for 2 minutes. The lamination conditions were a temperature of 120 ° C. and a pressure of 2 kg / cm ² , and three layers were simultaneously laminated. Further, heat curing was performed at 150 ° C. for 1 hour.

Adhesive; "Kemit Epoxy" TE5920 (Toray Industries, Inc.)
Solid content concentration 30 wt% Distribution of adhesive; A agent / B agent = 15/100 (2) PPS-NO having a thickness of 3000 μm was obtained under the same conditions as in Example 1, and the sheet was further longitudinally stretched into rolls. The film is stretched 3.9 times in the longitudinal direction at a temperature of 98 ° C., and then the film is supplied to a tenter.
Stretched 5 times, and then 270 in the subsequent heat treatment chamber in the same tenter
Heat treated for 10 seconds at ℃, biaxially oriented PPS with 150μm thickness
A film was obtained. (Film-1) The fiber sheet used in Example 1 was laminated on both surfaces of the film-1 obtained above via the adhesive used in Comparative Example 1. The lamination conditions are the same as in Comparative Example 1. (Laminate-3,
Comparative Example 2) (3) The adhesive of the configuration of Comparative Example 2 was laminated using the following urethane-based adhesive. The coating conditions were the same as in Comparative Example 2, and the lamination was performed at 80 ° C. under the condition of ² kg / cm ² . The curing condition of the adhesive was 60 ° C. for 3 days. (Laminate -4, Comparative Example 3) adhesives; produced by Toyo Morton Co., Ltd., "Adcoat" 76P ₁ (a solid fraction concentration of 32 wt%) distribution of the adhesive; main agent / curing agent = 100/1 (4) Comparative Example 2 PPS-BO (150 μm) used in Example 1 (Film-1, Comparative Example 4), PPS-NO used in Example 1 (150 μm)
m) (Sheet-1, Comparative Example 5) and the fiber sheet (250 μm) (Fiber sheet 1, Comparative Example 6) used in Example 3 were also evaluated as the laminate of the present invention. Table 1 shows the evaluation results.

Evaluation Table 1 shows the evaluation results of the properties of the laminate, film, and sheet of Example 1 and Comparative Examples 1 to 6.

The laminate of the present invention makes use of the heat resistance of the aromatic polyamide fiber sheet (Comparative Example 6), and has greatly improved dielectric breakdown strength, which was a problem of the fiber sheet.

Also, the impact resistance required for the electrically insulating material is not reduced. In addition, the resin impregnating property is excellent, making use of the features of the fiber sheet. In addition, PPS is attracting attention in this field
-BO (Comparative Example 4) has lower heat resistance and lower impact resistance and tear strength than the laminate of the present invention. Furthermore,
Poor impregnation of resin. Also, PPS-NO (Comparative Example-5)
It can be seen that the use of a simple substance is difficult in terms of heat resistance.

On the other hand, the conventional laminates (Comparative Examples 2 and 3) joined by an adhesive were not able to fully utilize the long-term heat resistance of the aromatic polyamide fiber sheet due to the thermal degradation of the adhesive. It depends on the heat resistance of the agent. Further, if the adhesive is suddenly exposed to a high temperature, the adhesive is softened, and dimensional change between the film and the fiber sheet causes interfacial peeling. Also,
The impact resistance of PPS-BO of the central layer of the laminate is low, especially PPS
When the thickness of -BO is increased, the PPS-BO layer is delaminated by the impact force.

In addition, in the case of laminating with an adhesive in the laminated structure of the present invention (Comparative Example-1), the heat resistance of the adhesive also affects, and the heat resistance of the fiber sheet cannot be utilized.

From the above results, the laminate of the present invention significantly reduces the conventional problem of electric insulation without lowering the excellent heat resistance and impact resistance of the aromatic polyamide fiber sheet and the resin impregnation. It can be seen that the improved laminate was obtained.

Example 2 100 μm PPS-NO and 100 μm under the same conditions as in Example 1.
m of aromatic polyamide fiber sheet was obtained. Further, a two-layer laminate of a fiber sheet and PPS-NO was prepared under the conditions of Example 1. However, at the time of lamination, a release substrate was used on the PPS-NO side in order to prevent the adhesion of PPS-NO. (Laminate-5) Evaluation Table 1 shows the evaluation results of the laminate of Example 2.

Although the long-term heat resistance is somewhat lower than that of the laminate of Example 1, the impact resistance and the tear strength are at the same level. Especially,
The reason why the long-term heat resistance at a high temperature is somewhat low is that PPS-NO is melted and the flatness of the laminate is slightly deteriorated. There was no peeling.

Example 3 PPS-NOs of various thicknesses were prepared under the conditions of Example 1.
On the other hand, the fiber sheet of the aromatic polyamide is 2 mil (50μ) of “Nomex” paper type 410 manufactured by DuPont.
m) Four types of laminates having different thickness configurations as shown in Table 1 were obtained under the conditions of Example 1 using those having a thickness of 5 mil (100 μm) and 10 mil (250 μm). . (Laminate-6-9) Evaluation The evaluation results of Example 3 are shown in Table 1. When the thickness ratio (A / [B + B ']) of the laminate of the present invention decreases,
The dielectric breakdown strength tends to decrease, and conversely, when the composition ratio increases, the heat resistance tends to decrease.

Example 4 The aromatic polyamide fiber sheet (50
Under the conditions of Example 1, PPS was melted between two layers (thickness: μm) and extruded directly from a die to be laminated. The lamination conditions are
The temperature was 25 ° C. and the pressure was 2 kg / cm ² . Further, the laminate was thermocompressed again at a temperature of 280 ° C. and a pressure of 10 kg / cm ² . (Laminate-10) Table 1 shows the evaluation results of the laminate. Almost the same characteristics as in Example 1 can also be used to produce the laminate of the present invention.

Claims (1)

(57) [Claims] 1. A laminate comprising a fiber sheet made of an aromatic polymer having no melting point and laminated on at least one surface of an unstretched polyphenylene sulfide sheet without using an adhesive.