JPH0636619A - Flat cable - Google Patents

Abstract

PURPOSE:To provide a flat cable having the characteristics of high flexibility even in high temperature atmosphere. CONSTITUTION:A plurality of flat conductors are laid in parallel between two insulation base materials comprising an insulation film of high polymer material and an adhesive layer, and then integrated therewith. In the flat cable so fabricated, the tensile elastic modulus of the insulation film material at 20 deg.C is equal to 600kg/mm<2> or less. The tensile elastic modulus of the resin composite of the adhesive layer is between 20kg/mm<2> and 300kg/mm<2> at 20 deg.C, and equal to or larger than 4kg/mm<2> at 80 deg.C. In addition, the peel strength of the adhesive layer and the flat conductor is equal to 30g or more as a value converted to 1mm width.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat cable used for wiring electric and electronic equipment, and more particularly to a flat cable having excellent bending characteristics.

[0002]

2. Description of the Related Art In recent years, in order to save wiring work and prevent erroneous wiring in response to the complicated wiring inside various equipment, internal wiring for video equipment, audio equipment, office automation equipment, computer equipment, etc. A flat multi-fiber cable is used as an electric wire. A flat cable is generally manufactured by sandwiching a plurality of conductors in parallel between two insulating base materials, heat-sealing the insulating base materials, and integrating them. A biaxially stretched polyethylene terephthalate (PET) film layer, which has excellent mechanical and electrical properties, is often used as the insulating base material. In this case, however, the PET films cannot be fusion-bonded to each other. It is necessary to provide an agent layer. So far, polyvinyl chloride (PVC), thermoplastic saturated copolyester, etc. have been mainly used for the adhesive layer. Further, there has been proposed an adhesive layer using a resin of a type that is cross-linked by an electron beam such as polyethylene. In FIG. 1, a plurality of flat conductors 3 arranged in parallel at intervals are sandwiched between two insulating films 1 made of a polymer material and an insulating base made of an adhesive layer 2, and the insulating bases are melted together. An example of bonding by wearing is shown.

Recently, flat cables are often used for wiring of movable parts, and along with this, the demand for bending resistance is also increasing. In order to improve the flex resistance of flat cables, it is generally necessary to increase the adhesion between the conductor and the insulating base material.Therefore, a resin with excellent adhesion to the conductor has been selected for the adhesive layer. Saturated copolymer polyesters were mainly used. For example, a PET film having a thickness of 25 μm and an adhesive layer of 40 to 5
In general, 0 μm is coated, and the bending characteristic value of a flat cable when a flat conductor having a thickness of 35 μm is used is generally 10 ⁶ order by the method of JIS, C5016.

[0004]

However, even this bending property value is a value at room temperature, and the bending resistance property in a high temperature atmosphere is not taken into consideration. The severely required bending resistance value recently required may be, for example, 10 ⁵ order in a high temperature atmosphere of 80 ° C. or 10 ⁷ order even at room temperature. In addition, bending resistance with a smaller radius of curvature may be required. However, conventional flat cables have not been able to meet such strict requirements.

[0005]

The present invention has been made to solve the above problems, and is characterized in that it is provided between two insulating base materials each including an insulating film made of a polymer material and an adhesive layer. In a flat cable in which a plurality of flat conductors are arranged in parallel and integrated, the material forming the insulating film has a tensile elastic modulus at 20 ° C. of 600 kg / mm ² or less, and the resin composition of the adhesive layer is The tensile elastic modulus is 20 kg / mm ² or more, 300 kg / mm ² or less at 20 ° C., and 4 kg / mm ² or more at 80 ° C., and the peel strength between the adhesive layer and the flat conductor at 80 ° C. is 1 mm width. The converted value is set to 30 g or more.

Here, the insulating film is preferably a biaxially stretched polyphenylene sulfide film, and it is preferable that the thickness (Ti) of the insulating film and the thickness (Ta) of the adhesive layer have the following relationship. Ta + Ti ≦ 90 μm

In the above flat cable, the resin composition of the adhesive layer contains 50 parts by weight or more of a saturated copolyester resin having crystallinity and a crystal melting point of 120 ° C. or higher and 150 ° C. or lower. In addition, it is characterized by containing 5 parts by weight or more of a saturated copolyester resin which is amorphous and has a glass transition temperature of 30 ° C. or higher. Further, in the cable, the resin composition of the adhesive layer contains at least 10 parts by weight of a resin containing an epoxy group and is cured.

The conductor used here has a thickness of 20 to 5
A flat annealed copper conductor having a thickness of 0 μm is preferable. Since hard copper and a copper-tin alloy have a small elongation, the bending property may be deteriorated when the radius of curvature is extremely small. However, when the bending radius is large, it may be used.

As the insulating film, polyethylene terephthalate (PET), polyethylene naphthalate (P
EN), polyarylate (PAR), polyphenylene sulfide (PPS), polysulfone (PSF), polyethersulfone (PES), polyetheretherketone (PEEK), polyetherimide (PEI),
Examples thereof include polyparabanic acid (PPA), polyamide (PA: nylon), polyimide (PI) and the like. Among these, the crystalline material such as PET, PEN, PPS, PA is preferably biaxially stretched. In particular, the bending property can be improved by using a biaxially stretched PPS film.

When the tensile modulus of elasticity of the insulating film at 20 ° C. exceeds 600 kg / mm ² , the bending property is deteriorated because it is too hard. Further, if the thickness of the insulating film is less than 10 μm, it is not preferable because the bending property is deteriorated due to a slight scratch or the like.

The resin composition of the adhesive layer has a tensile elastic modulus of 2
If it is less than 15 kg / mm ² at 0 ° C., the adhesive is likely to be deformed during bending, resulting in poor bending characteristics. Also, at the same temperature, 3
If it exceeds 00 kg / mm ² , flexibility becomes poor, so
When the radius of curvature is small, the bending property becomes poor. Further, if the tensile modulus at 80 ° C. is less than 4 kg / mm ² , the bending property at this temperature is poor. Conversely, 4 kg / mm
If it is ² or more, good bending properties can be obtained even in an atmosphere of 80 ° C. However, the peel strength between the conductor and the adhesive is 30 g / m
m or more is required. If it is less than 30 g / mm, it is considered that the conductor is easily peeled off from the adhesive layer during bending and the stress is concentrated on the conductor. Although the material is limited by the tensile elastic modulus in the present invention, this may be replaced by the bending elastic modulus.

The following resin compositions can be used for the adhesive layer. First, as the thermoplastic type, there are saturated copolyester type hot melt resin, polyamide type hot melt resin, polyolefin type (polyethylene, EVA, EEA, etc.) hot melt resin and the like. Among them, the polyester hot melt resin (thermoplastic saturated copolyester) has excellent adhesiveness to the conductor and high tensile elasticity, and is a material suitable for the adhesive layer of the present invention.

In the case of the saturated copolyester, the entire polymer has crystallinity and its crystal melting point is 120 ° C.
50 parts by weight or more of a saturated copolymerized polyester resin having a temperature of 150 ° C. or less, or 5 parts by weight or more, preferably 10 to 20 parts by weight of an amorphous, saturated copolymerized polyester resin having a glass transition temperature of 30 ° C. or more By containing it, the desired adhesive resin composition can be obtained. Further, polyolefin-based materials can be provided with more excellent adhesion performance if they are crosslinked with peroxide or ionizing radiation.

Examples of the thermosetting type include epoxy resin and urethane resin. Since the epoxy resin itself is very hard, it is preferable to add a rubber component to give flexibility. The curing method of the epoxy resin is generally thermal curing using amine or the like, but the curing agent may be selected optimally in consideration of the life of the adhesive and the curing conditions.
Epoxy acrylates and urethane acrylates can be cured by heat, but since they contain an acrylic group, they can be cured by ionizing radiation. The above-mentioned examples are merely examples, and various other resins can be used, and further, such resins can be used alone or in combination of two or more kinds.

In the adhesive layer, various flame retardants such as organic flame retardants such as chlorine, bromine and phosphorus, and inorganic flame retardants such as aluminum hydroxide and magnesium hydroxide, or Flame retardancy can be imparted by adding a flame retardant and a flame retardant aid such as antimony trioxide. The amount of flame retardant is 10 to 200 per 100 parts by weight of the resin used in the adhesive layer.
It is preferably in the range of parts by weight. Furthermore, various additives such as an antioxidant, a colorant, a lubricant, and a filler can be appropriately added to the resin composition of the adhesive layer.

If the thickness of the adhesive layer is not more than 20 μm, the conductor is not sufficiently filled, which is not suitable. further,
The thickness of the insulating base material including the insulating film and the adhesive layer is 9
It is preferably 0 μm or less. This is because if the thickness exceeds 90 μm, the strain applied to the conductor in the bent state of the flat cable becomes large, and the bending characteristics deteriorate.

The coating of the adhesive layer on the insulating film is performed by a roll coater method, a T-die extrusion method, or the like. In order to further strengthen the adhesive force between the insulating film and the adhesive layer, the surface of the insulating film may be subjected to corona treatment, or a primer or an anchor coating agent (AC agent) may be used.

[0017]

EXAMPLES The present invention will be described below with reference to examples and comparative examples. (Example A) An evaluation sample was prepared by the following procedure. First, the resin composition (adhesive layer) using the base polymer shown in Examples and Comparative Examples was prepared using a T-die extruder.
An insulating base film was prepared by extrusion coating on an insulating film having a thickness of 50 μm to a thickness of 50 μm. Next, a tin-plated annealed copper wire having a width of 1.0 mm and a thickness of 0.05 mm was sandwiched between the two obtained insulating base materials and laminated by a hot roll to obtain a flat cable sample.

In Examples 5, 6, 7 and Comparative Example 5,
Dissolve the adhesive in MEK, apply it on each insulating film using a roll coater, and make an insulating base material by drying, and further laminate and integrate, then leave it in a constant temperature bath at 160 ° C for 2 hours. The adhesive layer was thereby cured and then tested. In addition, in Example 3 and Comparative Example 3, after laminated and integrated, an electron beam with an acceleration voltage of 500 kV was irradiated at 10 Mrad to cure the adhesive layer, and then the test was conducted.

The samples were evaluated as follows. (1) Adhesion with conductor: Measure peel strength by peeling 180 ° at 25 ° C. (2) Bending characteristics: According to JIS C 5016. However, the bending radius of curvature was two types, 2.5R and 5.0R. The evaluation criteria are as follows. ◎… Excellent (10 times or more at 2.5R, 5,000 times or more at 5.0R) ○… Good (1 to 10,000 times at 2.5R, 1,000 to 5,000 at 5.0R)
Thousand times) × ... Poor (less than 1,000 times at 2.5R, less than 1,000 times at 5.0R)

The sample configurations and evaluation results of the examples and comparative examples are shown in Table 1 (Examples) and Table 2 (Comparative Examples).

[0021]

[Table 1]

[0022]

[Table 2]

In Examples 1 to 9, the insulating film has a tensile elastic modulus of 500 kg / mm ² or less, and the adhesive has a tensile elastic modulus of 20.
A flat cable that uses an insulating base material that has a temperature of 250 kg / mm ² or less at 80 ° C and 4 kg / mm ² or more at 80 ° C.
The bending property is also good. Comparative Example 1 uses aramid as the insulating film, but since the tensile modulus is very large, the bending property becomes poor at a radius of curvature of 2.5R. In Comparative Examples 2 and 3, the tensile modulus of elasticity of the adhesive at 80 ° C. is less than 4 kg / mm ² , but the bending property at this temperature is not sufficient. In Comparative Example 4, PVC is used for the adhesive layer, which has a large tensile elastic modulus but lacks adhesiveness with a conductor, and therefore has a poor bending property. In Comparative Example 5, the tensile modulus of the adhesive is extremely high and is 350 kg / mm ² , but in the case of 2.5R, cracks occur in the adhesive layer before the conductor, and the bending characteristics deteriorate.

(Example B) Examples and comparative samples for evaluation were prepared as follows. First, the insulating films shown in Tables 3, 4 and 5 were extrusion-coated with a predetermined thickness onto the insulating films shown in Tables 3, 4 and 5 using a T-die extruder to obtain respective insulating base materials. Next, between the obtained two insulating base materials, ten 35 μm thicknesses × 0.8 m are arranged at a pitch of 1.5 mm.
A tin-plated flat type annealed copper conductor having a width of m was sandwiched in parallel, and passed through a heat roller to be laminated and integrated to obtain a sample. Table 6 shows the composition of the adhesive, the tensile elastic force, and the adhesiveness with the conductor.

Then, the bending characteristics of the sample are measured according to JIS C.
It was measured by the method of 5016. The radius of curvature is JIS
In addition to the 4.8 mmR specified in s. The evaluation criteria are as follows. 4.8 mmR 20 ° C. 80 ° C. ◎… 10 million times or more 10 million times or more ○… 1 million times or more, less than 10 million times 1 million times or more, less than 10 million times ×… less than 1 million times less than 1 million times 2 In the case of 0.5 mmR 20 ° C. 80 ° C. ◎… 100,000 times or more, 100,000 times or more ○… 10,000 times or more, 100,000 times or less 10,000 times or more, 100,000 times or less ×… less than 10,000 times less than 10,000 times

[0026]

[Table 3]

[0027]

[Table 4]

[0028]

[Table 5]

[0029]

[Table 6]

In Examples 1 to 5, a PET film having a thickness of 25 μm was used as an insulating film, and an adhesive layer having a thickness of 50 μm was used.
This is the case where m, B, C, E, F, and H (see Table 6) are used. In both cases, both 4.8 mmR and 2.5 mmR showed good bending characteristics even in a high temperature atmosphere of 80 ° C.

Example 6 uses the PET film of Example 1 as 6
-Although it was changed to nylon, the same results as in Examples 1 to 5 were obtained. Example 7 has an insulating film of 25 μm
The thickness of PPS is 50 .mu.m and B is used as an adhesive. In Example 9, the insulating film is 50 .mu.m thick of PPS.
And 25 μm thick B was used as the adhesive. In both cases, the bending characteristics are better than in the case of PET,
10 ⁷ order in 4.8mmR, even 2.5mmR 10
⁵ orders were realized. Also, these showed superior results to PET even in a high temperature atmosphere. Example 8.10 is also PP
Although the S film was used, the total thickness of the insulating base material exceeded 90 μm, so that the flex resistance of the order of 10 ⁵ could not be obtained at 2.5 mmR.

On the other hand, in Comparative Example 1, the adhesive of Example 1 was changed to A, but the tensile modulus at 80 ° C. was 4 kg.
Since it is less than / mm ² , the bending property at the same temperature was not sufficient. In Comparative Example 2, the adhesive of Example 1 was used as D, but the tensile modulus was 20 kg / mm ² at 20 ° C.
And less than 4 kg / mm ² even at 80 ° C., sufficient bending characteristics could not be obtained at any temperature. Comparative Example 3 uses G as the adhesive of Example 1, and although the tensile modulus of elasticity is satisfied, there is no adhesive strength with the conductor and the bending characteristics are poor at both room temperature and high temperature. In Comparative Example 4, the insulating film of Example 1 was changed to aramid, but the tensile elastic modulus of the aramid film was 700 kg / mm ² , and the temperature was 20 ° C.
The flexing characteristics at are reasonable. However, at 80 ° C., the bending characteristics deteriorate even though the tensile elastic modulus of the adhesive is 10 kg / mm ² . In Comparative Examples 5 and 6, the PET film of Comparative Examples 1 and 3 was replaced with a PPS film. In Comparative Example 5, the bending property at high temperature was bad, and in Comparative Example 6, the bending property was bad even at room temperature.

[0033]

As described above, the flat cable of the present invention can obtain a flat cable having excellent bending characteristics even in a high temperature atmosphere by limiting the tensile elastic modulus of the resin composition of the insulating film and the adhesive layer. Can also,
If PPS is used as the insulating film, it is possible to obtain a flat cable having more excellent bending characteristics than before.
Therefore, when severe bending characteristics are required, it is an extremely effective wiring material.

[Brief description of drawings]

FIG. 1 is a sectional view of a flat cable of the present invention.

[Explanation of symbols]

 1 Insulation film 2 Adhesive 3 Flat conductor

Claims (5)

[Claims] 1. A flat cable in which a plurality of flat conductors are arranged in parallel between two insulating base materials each composed of an insulating film made of a polymer material and an adhesive layer, and integrated. Tensile elastic modulus at 20 ° C is 600
kg / mm ² or less, a tensile elastic modulus of the resin composition of the adhesive layer, 20 ° C. In 20 kg / mm ² or more, 300 kg / mm ² or less, 80
4 kg / mm ² or more at 80 ° C, and the peel strength between the adhesive layer and the flat conductor at 80 ° C is 1 m.
A flat cable characterized by having a value of 30 g or more in terms of m width. 2. The insulating film is a biaxially stretched polyphenylene sulfide film.
The flat cable described. 3. The flat cable according to claim 1, wherein the thickness (Ti) of the insulating film and the thickness (Ta) of the adhesive layer have the following relationship. Ta + Ti ≦ 90 μm 4. The resin composition of the adhesive layer contains 50 parts by weight or more of a saturated copolyester resin having crystallinity and a crystal melting point of 120 ° C. or higher and 150 ° C. or lower, or amorphous. 4. The flat cable according to claim 1, containing 5 parts by weight or more of a saturated copolyester resin having a glass transition temperature of 30 ° C. or higher. 5. The resin composition of the adhesive layer contains at least 10 parts by weight of a resin containing an epoxy group,
Claim 1, 2, characterized in that it is hardened.
Or the flat cable described in 3.