JP2870348B2 - Flat cable - Google Patents

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 electrical 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 reduce the wiring work and to prevent erroneous wiring in response to the complexity of wiring in various devices, internal wiring of video equipment, audio equipment, OA equipment, computer equipment and the like has been developed. A multi-core flat cable is used as an electric wire. In general, a flat cable is manufactured by sandwiching a plurality of conductors in parallel between two insulating base materials, heat-sealing the insulating base materials together, and integrating them. As the insulating base material, a biaxially stretched polyethylene terephthalate (PET) film layer having excellent mechanical properties and electrical properties is often used. In this case, the PET films cannot be fusion-spliced with each other. It is necessary to provide an agent layer. Heretofore, polyvinyl chloride (PVC), thermoplastic saturated copolymerized polyester, and the like have been mainly used for the adhesive layer. Further, there has been proposed an adhesive layer using a resin such as polyethylene which can be crosslinked by an electron beam. In FIG. 1, a plurality of flat conductors 3 arranged in parallel at intervals are sandwiched between two insulating substrates 1 each consisting of an insulating film 1 made of a polymer material and an adhesive layer 2, and the insulating substrates are thermally fused. An example of bonding by wearing is shown.

[0003] Recently, flat cables are often used for wiring of movable parts, and accordingly, demands for bending resistance have been increasing. In order to improve the bending resistance of a flat cable, it is generally necessary to increase the adhesion between the conductor and the insulating base material.Therefore, a resin that has excellent adhesion to the conductor is selected for the adhesive layer. Saturated copolymer polyesters were mainly used. For example, a 25 μm thick PET film may be provided with an adhesive layer of 40 to 5
A coating having a thickness of 0 μm is generally used, and the bending characteristic value of a flat cable when a 35 μm thick flat conductor is used is generally 10 ⁶ orders according to the method of JIS, C5016.

[0004]

However, even the bending characteristic values are values at room temperature, and no consideration is given to the bending resistance characteristics in a high-temperature atmosphere. The severe bending resistance characteristic value required recently may be, for example, 10 ⁵ orders in a high-temperature atmosphere of 80 ° C. or 10 ⁷ orders at room temperature. In addition, bending resistance with a smaller radius of curvature may be required. However, the conventional flat cable cannot meet such severe requirements.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the feature of the present invention is that a two-layer insulating substrate composed of an insulating film of a polymer material and an adhesive layer is provided. In a flat cable in which a plurality of flat conductors are arranged in parallel and integrated, the material constituting the insulating film has a tensile modulus at 20 ° C. of not more than 600 kg / mm ² , and the resin composition of the adhesive layer has The tensile modulus is 20 kg / mm ² or more and 300 kg / mm ² or less at 20 ° C., 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 reduced to 1 mm width. That is, the converted value is 30 g or more.

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

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

The conductor used here has a thickness of 20 to 5 mm.
It is preferably a flat type soft copper conductor of 0 μm. Hard copper or a copper-tin alloy has a small elongation, so that if the radius of curvature is extremely small, the bending characteristics may be degraded. However, if the radius is large, it may be used.

As an 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), and polyimide (PI). Among them, the crystalline materials such as PET, PEN, PPS, and PA are preferably biaxially stretched. In particular, if a biaxially stretched PPS film is used, the bending characteristics can be improved.

On the other hand, if the tensile elastic modulus at 20 ° C. of the insulating film exceeds 600 kg / mm ² , the bending properties are deteriorated because the film is too hard. Further, if the thickness of the insulating film is less than 10 μm, it is not preferable because bending characteristics are reduced due to slight scratches or the like.

The resin composition of the adhesive layer has a tensile modulus of 2
If the temperature is less than 15 kg / mm ² at 0 ° C., the adhesive tends to be deformed during bending, and the bending characteristics deteriorate. At the same temperature, 3
If it exceeds 00 kg / mm ² , the flexibility becomes poor.
When the radius of curvature is small, the bending characteristics deteriorate. Further, if the tensile modulus at 80 ° C. is less than 4 kg / mm ² , the bending characteristics at this temperature are poor. Conversely, 4 kg / mm
If it is ² or more, good bending characteristics can be obtained even in an 80 ° C. atmosphere. 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 stress is concentrated on the conductor. In the present invention, the material is limited by the tensile modulus, but this may be replaced by the flexural modulus.

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

In the case of the saturated copolymerized polyester, all the polymers have crystallinity, and the crystalline melting point is 120 ° C.
50 parts by weight or more of a saturated copolymerized polyester resin having a temperature of at least 150 ° C. or less, or 5 parts by weight or more, preferably 10 to 20 parts by weight of an amorphous, saturated glass transition temperature of 30 ° C. or more. By containing it, a desired adhesive resin composition can be obtained. Further, a polyolefin-based material can provide more excellent adhesive performance if it is crosslinked by peroxide or ionizing radiation.

The thermosetting type includes an epoxy resin and a urethane resin. However, since the epoxy resin itself is very hard, it is preferable to add a rubber component to impart flexibility. The curing method of the epoxy resin is generally thermal curing using an amine or the like, and the curing agent may be selected in consideration of the life of the adhesive and the curing conditions.
In the case of epoxy acrylate or urethane acrylate, heat curing is also possible, but since these contain an acrylic group, curing by ionizing radiation is also possible. The above-described examples are merely examples, and various other resins can be used. Further, such resins can be used alone or in combination of two or more.

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

If the thickness of the adhesive layer is not more than 20 μm, the burying property of the conductor is not sufficient, which is not appropriate. 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. If the thickness exceeds 90 μm, the strain applied to the conductor in a state where the flat cable is bent becomes large, so that the bending characteristics deteriorate.

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

[0017]

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, a resin composition (adhesive layer) using the base polymer shown in Examples and Comparative Examples was subjected to T-die extruder for 25 minutes.
Extrusion coating was carried out on a μm insulating film so as to have a thickness of 50 μm to prepare an insulating base film. 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 obtained two insulating base materials, and laminated and integrated by a heat roll to obtain a flat cable sample.

Examples 5, 6, 7 and Comparative Example 5
The adhesive is dissolved in MEK, coated on each insulating film using a roll coater, dried to produce an insulating base material, and further laminated and integrated, and then left in a constant temperature bath at 160 ° C. for 2 hours. Thus, the adhesive layer was cured, and then a test was performed. Further, in Example 3 and Comparative Example 3, after laminating and integrating, the adhesive layer was cured by irradiating 10 Mrad of an electron beam with an acceleration voltage of 500 kV, and then a test was performed.

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

Sample configurations and evaluation results of the examples and comparative examples are as shown in Table 1 (Example) and Table 2 (Comparative Example).

[0021]

[Table 1]

[0022]

[Table 2]

In Examples 1 to 9, the insulating film had a tensile modulus of 500 kg / mm ² or less and the adhesive had a tensile modulus of 20 kg / mm ² or less.
A flat cable using an insulating base material that is 250 kg / mm ² or less at 80 ° C and 4 kg / mm ² or more at 80 ° C.
Also, the bending characteristics are good. Comparative Example 1 uses aramid as the insulating film. However, since the tensile elasticity is very large, the bending characteristics are deteriorated when the radius of curvature is 2.5R. In Comparative Examples 2 and 3, the tensile modulus of the adhesive at 80 ° C. is less than 4 kg / mm ² , but the flexural properties at this temperature are not sufficient. Comparative Example 4 uses PVC for the adhesive layer, but has a large tensile modulus, but has poor adhesion to a conductor, and thus has poor bending properties. In Comparative Example 5, the adhesive had an extremely high tensile modulus of elasticity of 350 kg / mm ² , but in the case of 2.5R, cracks occurred in the adhesive layer prior to the conductor, degrading the bending characteristics.

(Example B) Examples for evaluation and samples for comparative example were prepared as follows. First, an adhesive described in the same table was extrusion-coated to a predetermined thickness on an insulating film described in Tables 3, 4, and 5 by a T-die extruder to obtain respective insulating base materials. Next, 10 pieces of 35 μm thick × 0.8 m at a pitch of 1.5 mm were placed between the two obtained insulating base materials.
A tin-plated flat type soft 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 elasticity, and the adhesiveness to the conductor.

The bending characteristics of the sample were measured according to JIS C
5016. The radius of curvature is JIS
In addition to the 4.8 mmR specified in the above, 2.5 mmR was also used. The evaluation criteria are as follows. In the case of 4.8 mmR 20 ° C 80 ° C ◎… 10,000,000 times or more 10,000,000 times or more ○… 1,000,000 times or more, but less than 10,000,000 times 1,000,000 times or more, less than 10,000,000 times ×… less than 1,000,000 times Less than 1,000,000 times 2 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, 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 a 50 μm PET film was used as an adhesive layer.
This is the case where m, B, C, E, F, and H (see Table 6) are used. In each case, both 4.8 mmR and 2.5 mmR exhibited good bending characteristics even in a high temperature atmosphere of 80 ° C.

Example 6 shows the PET film of Example 1
-It was changed to nylon, but the same results as in Examples 1 to 5 were obtained. Example 7 uses an insulating film of 25 μm
In Example 9, the insulating film was made of PPS having a thickness of 50 μm.
And B having a thickness of 25 μm was used as an adhesive. In any case, the bending characteristics are better than those of PET,
10 ⁷ order at 4.8 mmR, 10 at 2.5 mmR
⁵ orders were realized. Also, they exhibited better results than PET even in a high temperature atmosphere. Example 8.10 Also PP
Although an S film was used, since the total thickness of the insulating base material exceeded 90 μm, bending 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.
/ Mm ² , the bending characteristics at the same temperature were not sufficient. In Comparative Example 2, the adhesive of Example 1 was changed to D, but the tensile modulus was 20 kg / mm ² at 20 ° C.
, Even at 80 ° C., less than 4 kg / mm ² , so that sufficient bending characteristics could not be obtained at any temperature. In Comparative Example 3, G was used as the adhesive of Example 1. However, although the tensile elastic modulus satisfied the condition, there was no adhesive force with the conductor, and the bending characteristics were poor at both normal temperature and high temperature. Comparative Example 4 was obtained by changing the insulating film of Example 1 to aramid. The tensile elastic modulus of the aramid film was 700 kg / mm ^{2 and} was 20 ° C.
The bending characteristics at are reasonable. However, when the temperature reaches 80 ° C., the bending characteristics are deteriorated even though the tensile modulus of the adhesive is 10 kg / mm ² . Comparative Examples 5 and 6 are obtained by changing the PET films of Comparative Examples 1 and 3 to PPS films, but Comparative Example 5 has poor bending characteristics at high temperatures, and Comparative Example 6 has poor bending characteristics even at room temperature.

[0033]

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

[Brief description of the drawings]

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating film 2 Adhesive 3 Flat conductor

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01B 7/08

Claims (5)

(57) [Claims] 1. A flat cable in which a plurality of flat conductors are arranged in parallel and integrated between two insulating base materials comprising an insulating film of a polymer material and an adhesive layer, Tensile modulus at 20 ° C. is 600
kg / mm ² or less, and the tensile modulus of the resin composition of the adhesive layer is 20 kg / mm ² or more, 300 kg / mm ² or less at 20 ° C.
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 having a value of 30 g or more in terms of m width. 2. The method according to claim 1, wherein the insulating film is a biaxially stretched polyphenylene sulfide film.
The described flat cable. 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 has a crystallinity, and contains at least 50 parts by weight of a saturated copolymerized polyester resin having a crystal melting point of 120 ° C. or more and 150 ° C. or less. 4. The flat cable according to claim 1, wherein the flat cable contains 5 parts by weight or more of a saturated copolymerized polyester resin having a glass transition temperature of 30 ° C. or more. 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 cured
Or the flat cable according to 3.