JP2013182805A - Adhesive film and flat cable using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive film and a flat cable which are excellent in heat resistance.SOLUTION: The adhesive film includes an insulating film, an adhesive layer formed on the insulating film, and a heat-resistant layer interposed between the insulating film and the adhesive layer. The heat-resistant layer is composed of an engineering plastic which is soluble in an organic solvent and has a glass transition temperature of 180°C or higher.

Description

  The present invention relates to an adhesive film and a flat cable using the same.

  Flat cables are widely used as internal wiring cables for various electric and electronic devices such as OA devices such as printers and scanners, computer devices, video devices such as flat-screen televisions, acoustic devices, robots, and ultrasonic diagnostic apparatuses.

  A flat cable is a cable in which a plurality of conductors arranged in parallel are sandwiched and covered by an adhesive layer of two adhesive films, and has a thin thickness and excellent flexibility. The adhesive film used for the flat cable has an insulating film serving as a base material and an adhesive layer that is formed on the insulating film and adheres to a conductor.

  Since the flat cable is used as an internal wiring cable of an electronic device, the flat cable is required to satisfy the UL standard (for example, UL VW-1), and high flame resistance is required. Similarly, high flame retardancy is also required for adhesive films used for flat cables. Therefore, flame resistance is imparted to the flat cable by a method of providing a flame retardant member on the flat cable or a method of making the adhesive film used for the flat cable flame retardant.

As a method of providing a flame retardant member on the flat cable, a polyimide resin film having high flame retardancy is formed on the outermost layer of the flat cable to impart flame resistance to the flat cable.
Moreover, two methods can be considered as a method for making the adhesive film flame-retardant. One is a method of making the insulating film itself flame-retardant. This method is a method using a flame-retardant film as the insulating film. As the film having flame retardancy, for example, a film made of polyimide (PI) resin or polyphenylene sulfide (PPS) resin is used. The other is a method for making the adhesive layer flame-retardant. This method is a method in which a flame retardant is contained in the adhesive layer to impart flame retardancy to the adhesive layer.

  Thus, there are various methods for imparting flame retardancy to a flat cable. However, since polyimide resin films are very expensive, the method of forming a film on the outermost layer of the flat cable and the method of making the insulating film itself flame-retardant are compared with the method of containing a flame retardant in the adhesive layer. The cost tends to be high. For this reason, as a method of imparting flame retardancy to the flat cable, a method of incorporating a flame retardant into the adhesive layer of the adhesive film used for the flat cable is generally employed.

In recent years, in the method of adding a flame retardant to the adhesive layer, since the adhesive property of the adhesive layer is lowered, the conventional adhesive layer has a two-layer structure of the flame retardant adhesive layer and the adhesive layer, and the flame retardancy of the adhesive film and A method has been proposed to achieve both conductor adhesion (see, for example, Patent Document 1). Specifically, as shown in FIG. 5, the adhesive film 101 has a structure in which a flame-retardant adhesive layer 103 and an adhesive layer 104 are laminated on an insulating film 102. As the insulating film 102, a polyethylene terephthalate film having excellent heat resistance and chemical resistance is used. As the base resin for forming the flame retardant adhesive layer 103, a thermoplastic polyester resin having high adhesiveness is widely used. In many cases, a primer layer (not shown) is formed between the insulating film 102 and the flame-retardant adhesive layer 103 in order to enhance the adhesion. Then, as shown in FIGS. 6 and 7, the flat cable 110 includes a plurality of conductors 111 arranged in parallel.
It is formed by sandwiching and integrating the adhesive layers 104a and 104b of the pair of adhesive films 101a and 101b.
According to Patent Document 1, the amount of the flame retardant contained in each of the flame retardant adhesive layer and the adhesive layer can be adjusted. For this reason, while reducing the content of the flame retardant in the adhesive layer that adheres to the conductor and increasing the adhesiveness, the content of the flame retardant in the flame retardant adhesive layer can be increased to increase the flame retardance.

JP 2003-272451 A

  By the way, when the flat cable is used as an internal wiring material of an electric / electronic device, the flat cable is connected to the electric / electronic device via a connector fitted to a terminal portion of the flat cable. As shown in FIG. 8, the adhesive layer 104 is partially removed from the terminal portion of the flat cable, and the conductor 111 is exposed. When the connector 120 is attached to this terminal portion, as shown in FIG. 9, the connector pin 121 inside the connector 120 comes into contact with the conductor 111 by pressure and becomes conductive. At this time, pressure by the connector pin 121 is continuously applied to the terminal portion of the flat cable 110, and pressure is continuously applied to the conductor 111, the adhesive layer 104, the flame-retardant adhesive layer 103, and the insulating film 102. Thus, the flat cable 110 is connected to the electrical and electronic equipment at the terminal portion.

  However, in the terminal portion of the flat cable, there is a problem that the connection with the electric / electronic device becomes defective due to a temperature rise inside the housing accompanying the operation of the electric / electronic device, and a conduction failure occurs. As the temperature inside the housing of the electric / electronic device rises, the environmental temperature of the flat cable rises and the flat cable is heated. And in patent document 1, since a flame-retardant contact bonding layer is comprised from resin with low heat resistance, such as a thermoplastic polyester resin, a polyester resin is plasticized with a heat | fever and flows from under a conductor with the pressure of a connector pin. To do. As a result, as shown in FIG. 10, the thickness of the flame retardant adhesive layer 103 is reduced, and the contact pressure between the conductor 111 and the connector pin 121 is lowered, thereby causing poor conduction.

  The present invention has been made in view of such problems, and an object thereof is to provide an adhesive film and a flat cable excellent in heat resistance.

  A first aspect of the present invention includes an insulating film, an adhesive layer formed on the insulating film, and a heat-resistant layer interposed between the insulating film and the adhesive layer, and the heat-resistant layer includes: It is an adhesive film composed of an engineering plastic that is soluble in an organic solvent and has a glass transition temperature of 180 ° C. or higher.

  A second aspect of the present invention is the adhesive film according to the first aspect, wherein a primer layer is provided between the insulating film and the heat-resistant layer.

  According to a third aspect of the present invention, in the adhesive film of the first aspect or the second aspect, the engineering plastic is an adhesive film having a flame retardancy of V-1 or higher in the UL-94 standard.

According to a fourth aspect of the present invention, in the adhesive film according to the third aspect, the engineering plastic is polyamideimide, polyetherimide, polyethersulfone, polyphenylene ether, polysulfone, thermoplastic polyimide, polyarylate, polyaminobismaleimide. An adhesive film which is a liquid crystal polymer.

  According to a fifth aspect of the present invention, in the adhesive film of any one of the first to fourth aspects, the heat-resistant layer is selected from the group consisting of a bromine compound, a phosphorus compound, a nitrogen compound, and a metal compound as a flame retardant. Is an adhesive film that contains 1 part by weight or more and 100 parts by weight or less with respect to 100 parts by weight of the engineering plastic resin that constitutes the heat-resistant layer. .

  A sixth aspect of the present invention is the adhesive film according to any one of the first to fifth aspects, wherein the insulating film is polyethylene terephthalate having a thickness of 9 μm to 35 μm.

  According to a seventh aspect of the present invention, in the adhesive film of any one of the first to sixth aspects, the thickness Ta of the insulating film, the thickness Tb of the heat-resistant layer, and the thickness Tc of the adhesive layer are: The adhesive film satisfies the relationship of 0.5 ≦ Tb / Ta ≦ 1.5 and 1 ≦ (Tb + Tc) /Ta≦2.5.

  According to an eighth aspect of the present invention, a pair of the adhesive films according to any one of the first to seventh aspects are arranged so as to oppose the adhesive layer, and are arranged in parallel between the opposing adhesive layers. A plurality of conductors are flat cables in which the adhesive layers are bonded and integrated by bonding between the bonding layers.

  According to the present invention, an adhesive film and a flat cable excellent in heat resistance can be obtained.

It is sectional drawing of the adhesive film concerning one Embodiment of this invention. It is process drawing in the manufacturing method of the flat cable concerning one Embodiment of this invention. It is sectional drawing of the flat cable concerning one Embodiment of this invention. It is a figure showing the state where the flat cable concerning one embodiment of the present invention was connected to the connector. It is sectional drawing of the conventional adhesive film. It is process drawing in the manufacturing method of the conventional flat cable. It is sectional drawing of the conventional flat cable. It is a perspective view which shows the terminal part of the conventional flat cable. It is a figure which shows the state in which the conventional flat cable was connected to the connector. It is a figure explaining the connection failure of the conventional flat cable.

  Embodiments of an adhesive film according to the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of an adhesive film according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of a flat cable according to an embodiment of the present invention. FIG. 3 is a process diagram in the flat cable manufacturing method according to the embodiment of the present invention.

  As shown in FIG. 1, the adhesive film 1 of this embodiment has a structure in which a primer layer 5, a heat-resistant layer 3, and an adhesive layer 4 are sequentially laminated on an insulating film 2.

The insulating film 2 is a base material of the adhesive film 1, and in the flat cable 10, is a member that covers the inner adhesive layer 4 and the like and is located on the outermost surface. As the insulating film 2, it is possible to use films made of various engineering plastics such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polybutylene naphthalate (PBN), and polycarbonate (PC). it can. Among these, polyethylene terephthalate which is excellent in heat resistance and chemical resistance, has a large amount of market distribution, and is excellent in price and supply stability is preferable. The thickness of the insulating film is preferably 9 μm or more and 35 μm or less. If it is thinner than 9 μm, the heat resistance becomes insufficient, and if it is thicker than 35 μm, there is no softness and the bending property becomes poor. The PET film may be subjected to corona treatment or UV treatment on the surface to which the paint is applied to improve the adhesiveness with the adhesive.

  The primer layer 5 is a resin layer that improves the adhesion between the heat-resistant layer 3 and the insulating film 2, and is preferably provided when sufficient adhesion cannot be ensured. As the resin constituting the primer layer 5, known resins such as isocyanate, polyurethane, polyester, and epoxy can be used. The thickness of the primer layer is preferably 0.5 μm or more and 2 μm or less. If it is thinner than 0.5 μm, sufficient adhesion cannot be obtained, and if it is thicker than 2 μm, the heat resistance of the film is impaired.

The heat-resistant layer 3 is made of an engineering plastic that is soluble in an organic solvent and has a glass transition temperature of 180 ° C. or higher. Engineering plastic is a synthetic resin with enhanced heat resistance and strength, and is abbreviated as engineering plastic.
In the present embodiment, the heat-resistant layer 3 is formed by dissolving an engineering plastic constituting the heat-resistant layer 3 in an organic solvent, preparing a paint, applying the paint to an insulating film, and drying. For this reason, engineering plastics that are soluble in organic solvents are used. Among engineering plastics, those having a glass transition temperature of 180 ° C. or higher are used. This is because the heat-resistant layer does not soften even when the environmental temperature of the flat cable rises to 150 ° C., for example. Further, when a flat cable is formed by laminating a pair of adhesive films, the heat resistant layer does not soften in the temperature range of the laminate (160 ° C. or lower). Therefore, a resin layer excellent in heat resistance can be formed by using a specific engineering plastic for the heat resistant layer. That is, it is possible to suppress deformation of the heat-resistant layer and resin flow-out of the heat-resistant layer due to external environment heat and connector pin pressure.

The engineering plastic preferably has flame retardancy of V-1 or higher according to UL-94 standard. An engineering plastic that satisfies these characteristics has heat resistance and flame retardancy.
The flame retardancy of V-1 or higher in the UL-94 standard is an index indicating the flame retardancy (self-extinguishing property) of engineering plastics, and is evaluated as follows. A vertical combustion test is performed on the five test pieces (resins), a flame is applied to the lower end of the test piece and held for 10 seconds, and the flame is separated from the test piece. After the flame is extinguished, put it on for another 10 seconds to release the flame. And the flaming combustion duration after the end of the first and second flame contact, the total of the flammable combustion duration and the non-flame combustion duration after the end of the second flame contact, flaming combustion of 5 test pieces The determination of V-0, V-1, and V-2 is performed according to the total time and presence / absence of combustion drops (drip). If the first and second flammable combustion times are within 10 seconds, V-0, and if within 30 seconds, V-1 or V-2. Further, if the total of the second flammable combustion duration and the flameless combustion time is within 30 seconds, V-0, and if within 60 seconds, V-1 or V-2. Furthermore, if the total flame burning time of the five test pieces is within 50 seconds, it becomes V-0, and if within 250 seconds, it becomes V-1 or V-2. V-1 and V-2 are distinguished by the presence or absence of combustion fallen objects generated during combustion. When no fallen objects are produced, V-1 is obtained, and when they are produced, V-2 is obtained.

As an engineering plastic, the glass transition temperature is 180 ° C or higher, and UL
Those having flame retardancy of V-1 or higher in the -94 standard are polyamideimide (PAI), polyetherimide (PEI), polyethersulfone (PES), polyphenylene ether (PPE), polysulfone (PSF), heat There are plastic polyimide (TPI), polyarylate (PAR), polyamino bismaleimide (PABM), and liquid crystal polymer (PLC). These engineering plastics can be suitably used for the heat-resistant layer. Since the engineering plastic has heat resistance and flame retardancy, it is not necessary to add a flame retardant to the heat resistant layer.

On the other hand, even if it is an engineering plastic that does not have flame retardancy of V-1 or higher in the UL-94 standard, if the glass transition temperature is 180 ° C. or higher, a flame retardant is contained in the heat-resistant layer. Can provide sex.
As the flame retardant to be contained, bromine compounds, phosphorus compounds, nitrogen compounds, and metal compounds can be used. Examples of bromine compounds include brominated flame retardants such as 1,1′-ethylenebis (pentabromobenzene) and ethylenebis (tetrabromophthalimide), and examples of phosphorus compounds include phosphate esters, condensed phosphate esters, and phosphate acids. Phosphorus flame retardants such as melamine, phosphate metal salt, phosphazene, ammonium polyphosphate, phosphate frit, etc., as nitrogen compounds, nitrogen flame retardants such as melamine cyanurate and melamine oligomers, and as metal compounds, Inorganic flame retardants such as antimony trioxide, magnesium hydroxide, aluminum hydroxide, hydrotalcite, zinc borate, zinc stannate and calcium borate can be used. These flame retardants may be used alone or in combination of two or more.

  The content of the flame retardant is preferably 1 part by weight or more and 100 parts by weight or less with respect to 100 parts by weight of the resin constituting the heat resistant layer. When the amount is less than 1 part by weight, it becomes difficult to impart sufficient flame retardancy to the heat-resistant layer. On the other hand, when the amount is more than 100 parts by weight, when the heat-resistant layer is formed, the coating property of the paint for the heat-resistant layer is not stable, and it becomes difficult to increase the line speed of the coater.

  In addition, even if it is an engineering plastic which has a flame retardancy of V-1 or higher in the UL-94 standard, the flame retardant may be included in the case of further imparting flame retardancy depending on the application. In this case, the type of flame retardant and the content thereof are the same as described above.

  The thickness of the heat-resistant layer is preferably 5 μm or more and 20 μm or less. If the thickness is less than 5 μm, the contact pressure of the connector pin cannot be maintained during use, which may result in poor conduction. If the thickness is greater than 20 μm, the flexibility is lost and the bendability becomes poor.

  In addition, it is preferable that the engineering plastic constituting the heat-resistant layer contains rubber or other resin. As the rubber, styrene rubber such as styrene butadiene rubber (SBR) and styrene ethylene butylene styrene block copolymer (SEBS), nitrile rubber, chloroprene rubber, isoprene rubber, butyl rubber and the like can be used. As other resins, polyester resins, polyisocyanates, resins having a carbodiimide group, and the like can be used. By further containing these rubbers and other resins, the adhesion between the heat-resistant layer and other layers such as an insulating film and an adhesive layer can be improved.

  Moreover, it is preferable to contain a plasticizer in the heat-resistant layer. By including a plasticizer, the adhesion between the heat-resistant layer and the other layers to which the heat-resistant layer is bonded can be improved. As the plasticizer, an aromatic condensed phosphate ester which can simultaneously impart flame retardancy is preferable. However, since the heat resistance of the heat-resistant layer is lowered when the content of the plasticizer is large, the content of the plasticizer is preferably 10 parts by weight or less with respect to 100 parts by weight of the resin constituting the heat-resistant layer.

  In addition to the above flame retardants and plasticizers, the heat-resistant layer may contain antioxidants, colorants, thickeners, cross-linking agents, cross-linking aids, copper damage inhibitors, anti-static agents, UV absorbers as necessary. It is possible to add agents, light stabilizers and hydrolysis inhibitors.

  The adhesive layer 4 is a layer that is formed on the heat-resistant layer 3 and adheres to the conductor 11 in the flat cable 10. The resin constituting the adhesive layer 4 is preferably a polyester resin or polyurethane resin having a softening temperature of 160 ° C. or less and good adhesion to the conductor. By using these resins, it is possible to sufficiently soften the resin and embed the conductor in the adhesive layer in the laminate when manufacturing the flat cable from the adhesive film. As a result, the heat-resistant layer occupies most of the space between the conductor and the insulating film, and the contact pressure can be maintained for a long time even when contact pressure is applied at the terminal portion when the flat cable is used.

  The thickness of the adhesive layer 4 should just be a thickness which can embed a conductor in an adhesive layer when forming a flat cable. When a conductor having a thickness of 22 μm or more and 50 μm or less is used, the thickness of the adhesive layer is preferably 12 μm or more and 30 μm or less. If it is thinner than 12 μm, it is difficult to embed a conductor when manufacturing a flat cable, and if it is thicker than 30 μm, the resin flows from the adhesive layer.

  Since the adhesive layer 4 is located inside the insulating film 2 and the heat-resistant layer 3 in the flat cable 10, it is not necessary to add a flame retardant to the adhesive layer 4. When the adhesive layer 4 does not contain a flame retardant, the adhesiveness of the adhesive layer 4 does not decrease. Moreover, even if it contains a flame retardant, it is preferable that content of the flame retardant in an contact bonding layer is 100 weight part or less with respect to 100 weight part of resin which comprises an contact bonding layer. If content of the flame retardant in an contact bonding layer is in the said range, a flame retardance can be improved, without reducing adhesiveness excessively.

Next, the manufacturing method of the adhesive film of this embodiment is demonstrated.
First, as the insulating film 2, for example, a polyethylene terephthalate film having excellent heat resistance and chemical resistance is prepared. In addition, as the polyethylene terephthalate film, a surface on which the coating is applied is subjected to corona treatment or UV treatment. Then, a primer layer 5 is formed on the insulating film 2 by applying the primer layer paint to the insulating film 2 using a slot die coater and drying the paint.

Subsequently, the paint for the heat-resistant layer is adjusted. As a resin constituting the heat-resistant layer 3, an engineering plastic that is soluble in an organic solvent and has a glass transition temperature of 180 ° C. or higher and flame retardancy of V-1 or higher in accordance with UL-94 standards, such as polyetherimide, is used. Use. This resin is dissolved in an organic solvent such as methylene chloride to prepare a paint for the heat-resistant layer. The organic solvent for dissolving the resin is not particularly limited. For example, toluene, xylene, tetrahydrofuran, methylene chloride, chloroform, dimethyl sulfoxide, diethyl sulfoxide, N, N-dimethylformamide, N, N-diethylformamide, N, N -Diethylacetamide, N, N diethylacetamide, N-methyl-2-pyrrolidone, 1,4-dioxane, dioxolane can be mentioned. These organic solvents may be used alone or as a mixed solvent composed of two or more.
Furthermore, in this embodiment, a flame retardant or a plasticizer is added to the paint for the heat-resistant layer. The heat-resistant layer 3 is formed by applying the prepared paint for the heat-resistant layer to the primer layer 5 using a die coater and drying it.

Subsequently, the adhesive for the adhesive layer is adjusted. As a resin constituting the adhesive layer 4, a polyester resin having high adhesion to the conductor 11 is used. This resin is dissolved in an organic solvent such as toluene to prepare an adhesive for the adhesive layer. When a flame retardant is contained in the adhesive layer, a flame retardant is added to the adhesive. The adjusted adhesive is applied to the heat-resistant layer using a die coater and dried to form an adhesive layer, thereby obtaining the adhesive film of this embodiment.

  Thus, in the adhesive film of this embodiment, the heat resistant layer is interposed between the insulating film and the adhesive layer, the resin constituting the heat resistant layer is soluble in an organic solvent, and the glass transition temperature is 180 ° C. This is the engineering plastic. For this reason, an adhesive film is excellent in heat resistance, and the resin flow of a heat resistant layer by heating does not arise. Moreover, since an adhesive film has a heat resistant layer excellent in heat resistance, the insulating film which is a base material is not limited, and there is no need to use a specific film such as a conventional polyimide excellent in heat resistance.

  And since the resin which has the flame retardance more than V-1 by UL-94 specification is used as engineering plastic, it is not necessary to make a heat resistant layer contain a flame retardant. And when a flame retardant is not contained, since the adhesiveness of a heat-resistant layer does not fall, the adhesiveness of a heat-resistant layer and another layer can be improved. On the other hand, when a flame retardant is contained, the flame retardancy of the heat-resistant layer can be further improved.

  Further, it is preferable that the relational expression 0.5 ≦ Tb / Ta ≦ 1.5 is satisfied, where Ta is the thickness of the insulating film and Tb is the thickness of the heat-resistant layer. When it is less than 0.5, it becomes difficult to impart sufficient flame retardancy, and when it exceeds 1.5, the adhesive film becomes hard and the flexibility is lowered. Furthermore, it is preferable that the relational expression 1 ≦ (Tb + Tc) /Ta≦2.5 is satisfied when the thickness of the adhesive layer is Tc. If it is less than 1, it will be difficult to impart flame retardancy and adhesion to the adhesive film, and if it exceeds 2.5, the flexibility of the adhesive film will be reduced.

(Flat cable)
Next, an embodiment according to the flat cable of the present invention will be described. As shown in FIG. 3, in the flat cable 10, the pair of adhesive films 1 a and 1 b obtained as described above are integrated with the conductor 11 sandwiched therebetween with the adhesive layers 4 a and 4 b facing each other. For the integration of the adhesive layers 4a and 4b, the adhesive layers 4a and 4b are fixed to each other by laminating a pair of adhesive films 1a and 1b at a temperature of 160 ° C. or lower. At this time, since the glass transition temperature of the resin constituting the heat-resistant layers 3a and 3b of the adhesive films 1a and 1b is 180 ° C. or higher, it is possible to prevent the resin of the heat-resistant layers 3a and 3b from flowing due to heat from the lamination. In addition, when the lamination temperature exceeds 160 ° C., the insulating film as the base material contracts, and the dimensions of the adhesive film may vary.

In a conventional flat cable, an adhesive film having a low-heat-resistant flame-retardant adhesive layer and an adhesive layer is bonded and integrated with a conductor interposed therebetween. For this reason, when the connector is connected to the terminal portion of the flat cable, the resin constituting the flame retardant adhesive layer is plasticized and flows due to the increase in the contact pressure of the connector pin and the environmental temperature, and the connector pin and the conductor flow. Reduce the contact pressure with. And conduction failure occurs.
On the other hand, in the flat cable of this embodiment, an adhesive film having a heat resistant layer and an adhesive layer excellent in heat resistance is bonded and integrated with a conductor interposed therebetween. According to the flat cable of this embodiment, as shown in FIG. 4, even if the environmental temperature of the flat cable is increased, the flow of the resin in the heat-resistant layer is suppressed, so that poor conduction is unlikely to occur. Moreover, since the flat cable is manufactured from an adhesive film that is thin and excellent in mechanical strength, it has heat resistance, flexibility, and mechanical strength, and is thin.

In addition, many heat-resistant resins are generally opaque and colored. When the outermost surface of a flat cable is covered with a heat-resistant resin, the color of the flat cable produced is limited to the color of the heat-resistant resin. Is done. However, according to the flat cable of the present invention, the heat-resistant layer having heat resistance is located on the inner side of the insulating film. Therefore, by directly adding the colorant to the insulating film, it is not affected by the color of the heat-resistant resin. The color of the flat cable surface can be selected. That is, a highly versatile white flat cable can be obtained.

  The adhesive film and flat cable of the Example concerning this invention were manufactured with the following method and conditions. These examples are examples of the adhesive film and the flat cable according to the present invention, and the present invention is not limited to these examples.

  First, a paint for the heat-resistant layer was prepared. Polyetherimide (glass transition temperature 217 ° C., Ultem 1000, manufactured by SABIC) was used as the resin (base resin) constituting the heat-resistant layer 3. 100 parts by weight of polyetherimide was dissolved in 250 parts by weight of methylene chloride (special grade reagent, manufactured by Wako Pure Chemical Industries) as an organic solvent. Furthermore, in a solvent, 80 parts by weight of aluminum phosphate (Exolit OP935, manufactured by Clariant) as a flame retardant, 20 parts by weight of titanium dioxide (R820, manufactured by Ishihara Sangyo) as a pigment, and a condensed phosphate ester ( 3 parts by weight of CR-741 (manufactured by Daihachi Chemical Co., Ltd.) was added to prepare a paint (paint A) having the composition A for the heat-resistant layer shown in Table 1.

  Moreover, it carried out similarly to the said coating material A, and adjusted the coating material (paint BD) of the composition BD shown in Table 1. The coating materials B to D were adjusted in the same manner as the coating material A, except that the base resin constituting the heat-resistant layer was changed. As the base resin, polyamide B (glass transition temperature 275 ° C., Torlon 4000T, manufactured by SOLVAY) is used for paint B, polyethersulfone (glass transition temperature 225 ° C., E2020P, manufactured by Mitsui Chemicals) is used for paint C, and polysulfone (glass is used for paint D). A transition temperature of 185 ° C., Udel P-1700, manufactured by Solvay) was used.

  Next, the adhesive used for the adhesive layer 4 formed on the heat-resistant layer was adjusted. For the base resin of the adhesive for the adhesive layer, 25 parts by weight of Byron 200 (glass transition temperature 67 ° C., manufactured by Toyobo), 15 parts by weight of Byron 103 (glass transition temperature 47 ° C., manufactured by Toyobo) as polyester resins , And 60 parts by weight of Byron 670 (glass transition temperature 7 ° C., manufactured by Toyobo Co., Ltd.) were used. These resins are dissolved in a mixed solvent of 60 parts by weight of methyl ethyl ketone and 240 parts by weight of toluene. Further, 50 parts by weight of magnesium hydroxide (Kisuma 5L, manufactured by Kyowa Chemical Industry) as a flame retardant is added to the adhesive layer. The adhesive of composition 1 (adhesive 1) was prepared. Table 2 shows the adjustment conditions for the adhesive 1. Moreover, the adhesive agent (adhesive agent 2) of the composition 2 shown in Table 2 was adjusted similarly to the adhesive agent 1. Adhesive 2 was prepared in the same manner as Adhesive 1 except that no flame retardant was added.

  Next, the coating material used for the primer layer 5 formed in the insulating film 2 was adjusted. 100 parts by weight of a polyester resin (UE3220, manufactured by Unitika) as a base resin is dissolved in a mixed solvent of toluene and methyl ethyl ketone, and 5 parts by weight of hexamethylene diisocyanate (TPA-100, manufactured by Asahi Kasei Chemicals) is added to form a polyurethane resin. A primer layer coating consisting of

Example 1
Then, the adhesive film 1 of Example 1 was manufactured using the coating material A and the adhesive agent 1 which were adjusted above. As the insulating film 2, a PET film (emblet, manufactured by Unitika) having a thickness of 12 μm and one side corona-treated was prepared. The insulating film 2 was coated with a primer layer paint using a slot die coater and dried at 100 ° C. to form a primer layer 5 having a thickness of 1 μm. Then, the heat-resistant layer 3 having a thickness of 12 μm was formed by applying the coating material A for the heat-resistant layer to the primer layer 5 and drying it. Finally, the adhesive 1 for the adhesive layer was applied to the heat-resistant layer 3 and dried to form the adhesive layer 4 having a thickness of 12 μm, and the adhesive film of Example 1 was manufactured.

  Here, the heat resistance of the adhesive film of Example 1 was evaluated. As a heat resistance evaluation method, a 12 μm-thick heat-resistant layer (paint A) and a 12-μm thick adhesive layer (adhesive 1) are formed on a metal plate, and a diameter of 1 mm is formed on the laminated resin layer. A cylindrical metal bar is pressed at a pressure of 2 MPa, and a current tester is inserted between the metal plate and the metal bar. And when it was set | placed in 80 degreeC atmosphere and it did not conduct | electrically connect between metals within 24 hours, it was set as the pass. As a result, it was found that the resin layer (heat-resistant layer) formed from the coating material A was excellent in heat resistance. The above evaluation results are shown in Table 3.

Next, a flat cable 10 was manufactured using the adhesive film 1. In this example, a flat rectangular soft conductor having a width of 0.3 mm and a thickness of 22 μm was used as the conductor 11. After 50 conductors 11 are arranged in parallel at a pitch of 0.5, the upper and lower surfaces of these conductors 11 are laminated with a pair of adhesive layers 4a and 4b of adhesive films 1a and 1b (at a temperature of 150 ° C.) to be integrated. The flat cable 10 of this example was manufactured.

The adhesiveness and flame retardancy of the manufactured flat cable 10 were evaluated.
Adhesiveness was evaluated by conducting a 180 ° peel test (peel rate 50 mm / min) of a flat conductor on the terminal portion of the flat cable, and measuring the peel strength of the flat cable. In this example, those having a peel strength of 0.6 kN / m or more were accepted. The flat cable of Example 1 was found to have excellent peelability with a peel strength of 0.6 kN / m or more.
In addition, flame retardancy was evaluated by implementing UL VW-1 based on UL1581. Specifically, as a vertical burning test of a flat cable, with a flat cable (sample) with an indicator held vertically, a burner at an angle of 20 ° at a distance of 250 mm from the indicator with respect to the flat cable. The operation of (fired fuel: methane gas, burner output: 500) was applied to the flame for 15 seconds and paused for 15 seconds was repeated 5 times. After that, a flame retardant was passed if the after flame did not exceed 60 seconds, the indicator did not burn more than 25%, and the cotton at the bottom of the sample did not burn due to falling objects. . When the flame retardance of the flat cable of Example 1 was measured, it was a flame retardance pass.

(Examples 2 to 4)
In Examples 2 to 4, as shown in Table 3, except that the heat-resistant layer paints B to D and the adhesive layer adhesive 1 or 2 are combined and the thickness of the insulating film or the like is changed as appropriate. In the same manner as in Example 1, an adhesive film and a flat cable were produced. When the heat resistance of the adhesive films produced in Examples 2 to 4 was measured in the same manner as in Example 1, it was found that any of the adhesive films was excellent in heat resistance. Moreover, about the flat cable of Examples 2-4, when adhesiveness and a flame retardance were evaluated like Example 1, it turned out that it is excellent in adhesiveness and a flame retardance also in any flat cable.

(Comparative Example 1)
In Comparative Example 1, a paint having the composition E shown in Table 1 (paint E) was used as the paint for the heat-resistant layer. For paint E, polyurethane resin (Byron UR4800, manufactured by Toyobo Co., Ltd., glass transition temperature 106 ° C.) was used as the base resin of the heat-resistant layer. Specifically, an adhesive film of Comparative Example 1 was produced using the prepared paint E and adhesive 1. A primer layer having a thickness of 1 μm was formed on the same insulating film as in Example 1 by applying a primer layer coating using a slot die coater and drying at 100 ° C. And the coating layer E for heat-resistant layers was apply | coated to the primer layer, and it dried and formed the heat-resistant layer with a thickness of 1 micrometer. Finally, the adhesive 1 for the adhesive layer was applied to the heat-resistant layer and dried to form an adhesive layer having a thickness of 26 μm, and the adhesive film of Example 1 was manufactured.

When the heat resistance of the produced adhesive film was evaluated in the same manner as in Example 1, it was found that the adhesive film of Comparative Example 1 was inferior in heat resistance. In Comparative Example 1, since the glass transition temperature of polyurethane used as the base resin of the heat-resistant layer was as low as 106 ° C., the heat resistance was insufficient.
Moreover, the flat cable was manufactured using this adhesive film. When the flat cable of Comparative Example 1 was evaluated, it was found that although it was excellent in adhesion and flame retardancy, its heat resistance was insufficient.

(Comparative Example 2)
In Comparative Example 2, a coating liquid (paint F) having the composition F shown in Table 1 was used as the paint for the heat-resistant layer. For the paint F, a polyester resin (Byron 200, manufactured by Toyobo Co., Ltd., glass transition temperature 67 ° C.) was used as the base resin of the heat-resistant layer. Specifically, an adhesive film of Comparative Example 2 was produced using the prepared paint F and adhesive 2. A primer layer having a thickness of 1 μm was formed on a 250 μm insulating film by applying a primer layer coating using a slot die coater and drying at 100 ° C. Then, a heat-resistant layer having a thickness of 10 μm was formed by applying paint F for the heat-resistant layer to the primer layer and drying it. Finally, the adhesive 2 for the adhesive layer was applied to the heat-resistant layer and dried to form an adhesive layer having a thickness of 12 μm, whereby the adhesive film of Example 1 was produced.

When the heat resistance of the produced adhesive film was evaluated in the same manner as in Example 1, it was found that the adhesive film of Comparative Example 1 was inferior in heat resistance.
Moreover, the flat cable was manufactured using this adhesive film. When the flat cable of Comparative Example 1 was evaluated, it was found that although it was excellent in adhesion and flame retardancy, its heat resistance was insufficient.

1 (1a, 1b) Adhesive film 2 Insulating film 3 (3a, 3b) Heat-resistant layer 4 (4a, 4b) Adhesive layer 5 Primer layer 10 Flat cable 11 Conductor 20 Connector 21 Connector pin

Claims (8)

An insulating film;
An adhesive layer formed on the insulating film;
A heat-resistant layer interposed between the insulating film and the adhesive layer,
The adhesive film, wherein the heat-resistant layer is composed of an engineering plastic that is soluble in an organic solvent and has a glass transition temperature of 180 ° C or higher. The adhesive film according to claim 1,
An adhesive film comprising a primer layer between the insulating film and the heat-resistant layer. In the adhesive film according to claim 1 or 2,
An adhesive film characterized in that the engineering plastic has flame retardancy of V-1 or higher according to UL-94 standard. In the adhesive film according to claim 3,
An adhesive film, wherein the engineering plastic is polyamideimide, polyetherimide, polyethersulfone, polyphenylene ether, polysulfone, thermoplastic polyimide, polyarylate, polyaminobismaleimide, or liquid crystal polymer. In the adhesive film according to any one of claims 1 to 4,
The heat-resistant layer contains at least one selected from the group consisting of a bromine compound, a phosphorus compound, a nitrogen compound, and a metal compound as a flame retardant,
The adhesive film, wherein the flame retardant is contained in an amount of 1 to 100 parts by weight with respect to 100 parts by weight of the engineering plastic resin constituting the heat-resistant layer. In the adhesive film according to any one of claims 1 to 5,
The said insulating film is a polyethylene terephthalate whose thickness is 9 micrometers or more and 35 micrometers or less, The adhesive film characterized by the above-mentioned. In the adhesive film according to any one of claims 1 to 6,
The thickness Ta of the insulating film, the thickness Tb of the heat-resistant layer, and the thickness Tc of the adhesive layer are 0.5 ≦ Tb / Ta ≦ 1.5 and 1 ≦ (Tb + Tc) /Ta≦2.5. An adhesive film characterized by satisfying the above relationship.   A pair of adhesive films according to any one of claims 1 to 7 are arranged so as to oppose the adhesive layer, and a plurality of conductors arranged in parallel between the opposing adhesive layers are the adhesive A flat cable characterized by being bonded and integrated by bonding between layers.

Images