JPH0313316A - Connecting material and connecting method - Google Patents

Abstract

PURPOSE:To make use of high frequency induction heating, and enable uniform and even connection to be carried out surely by forming conductive long-fibers with a specific diameter and length into a non-woven fabric shape, in which the basis weight of the conductive fibers is specified, together with thermoplastic resin. CONSTITUTION:Conductive long-fibers of equivalent diameter 10-100mum and length 20mm or longer are formed into a non-woven fabric shape, in which the basis weight of the conductive long-fibers is 50-400g/m<2>, together with thermoplastic resin. For example, 50 pts. of iron long-fibers with the average length 6mm and equivalent diameter 35mum produced by steel wool method are opened in the random direction by air flow random webbing method, following this, 50 pts. of polypropylene fibers having the average length 6mm and diameter 0.07mm are added thereto so as to get entangled with the iron long-fibers and make it into a mat-shape, and then a non-woven fabric is formed by conducting heat press at 230-250 deg.C. The non-woven fabric has 0.2mm thickness, and the basis weight of the iron long fibers is 50g/cm<2>. The non-woven fabric obtained is cut into the size of the outline of a spiral coil, and then mounted on a high frequency heating coil in holding it between two translucent molding plates, which are adhered to each other by the use of an oscillator for high frequency induction heating.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a joining member and a joining method using high frequency induction heating. More specifically, the present invention relates to a joining member and a joining method using high-frequency induction heating for effectively joining a relatively wide area.

[Prior Art] Various members and methods have conventionally been proposed as joining members or joining methods for molding synthetic resin molded products using high-frequency induction heating.

For example, Japanese Patent Application Laid-Open No. 48-49828 discloses that a wire mesh is interposed between the bonding surfaces of plastics to be bonded and induction heating is applied from the outside, thereby melting the synthetic resin on the bonding surfaces and pressing the bonded surfaces together. We are proposing a method of gluing. JP-A No. 52-150447 discloses that a conductive material and a crosslinking resin monomer are sandwiched between adherends, at least one of which is a polyolefin synthetic resin, and a high frequency is applied to these to bond the adherends together. We are proposing a method of gluing. Furthermore, Japanese Patent Application Laid-open No. 61-57329 discloses that a predetermined amount of 8 to 120 μm in diameter and 2 to 18 mm in length is added to a thermoplastic synthetic resin made of the same material as the synthetic resin parts to be joined. We have proposed a bonding component that includes gold, am fiber, and a coupling agent, in which the metal fibers are oriented in the direction of magnetic flux generated by a high-frequency induction coil during bonding.

[The problem that the invention attempts to solve I! ! ] In the high-frequency induction heating method using a wire mesh disclosed in JP-A-48-49828, when attempting to bond a relatively large area, local abnormal heat generation occurs along the outer periphery of the coil, that is, the wire mesh etc. There is a problem in that uniform heat-generating bonding is difficult because of the edge effect that occurs when heating.

The method disclosed in Japanese Patent Application Laid-open No. 52-150447 uses a mesh, powder, or zigzag-like cotton material as the conductive material, but the mesh has the same problems as when using the wire mesh described above. Has a point. In addition, in the case of a powder-like material or a cotton-like material, uneven distribution of the conductive material is unavoidable, and as a result, rapid partial heat generation occurs in areas where there is a large amount of conductive material, making it difficult to generate uniform heat generation. Although this is good for bonding a relatively small area, it has the problem that it makes it difficult to bond uniformly over a relatively wide area.

The method disclosed in Japanese Unexamined Patent Publication No. 61-57329 uses a joining component in which short metal fibers are oriented in the same direction as the magnetic flux generated by a high-frequency induction coil in a thermoplastic synthetic resin. According to this method, due to the shape of the high-frequency induction coil, 1/2 of the short metal fibers have a portion that does not match the direction of the magnetic flux, resulting in uneven heat generation.

[Means for Solving the Problems] The present invention provides a non-woven fabric in which conductive long fibers with an equivalent diameter of 10 to 100 μm and a length of 20 mm or more are combined with a thermoplastic resin and have a basis weight of 50 to 400 g/m2. Provided is a joining member formed by high frequency induction heating.

Furthermore, the present invention provides a bonding member formed by laminating the above bonding member on a thermoplastic resin film using high-frequency induction heating.

The present invention further provides the method of sandwiching the joining member between surfaces to be joined of objects to be joined, and then generating heat in the joining member by high-frequency irradiation to melt the thermoplastic resin and integrate the objects to be joined. The present invention provides a joining method consisting of the following.

The conductive long fibers used in the present invention may be long fibers made of metal that generates an induced current by electromagnetic induction, such as iron, stainless steel, aluminum, copper, etc. obtained by wire cutting method, focused drawing method, melt spinning method, etc. A preferable example is long metal fibers such as copper alloy. Further, these long metal fibers may be plated with zinc or tin, and the most preferable long metal fibers include iron with high magnetic permeability, 3.
It is a long fiber made of stainless steel such as 04.316.430 series.

The conductive long fibers have an equivalent diameter of 10 to 100 μm, preferably 30 to 60 μm. If the equivalent diameter is smaller than the above lower limit, the heat generation efficiency at frequencies of 300 to 700 KHz, which are normally used for high-frequency induction, will be poor, and the cut resistance against fiber opening for random arrangement during the production of joining parts will decrease, so it is preferable. If the equivalent diameter exceeds the above upper limit, the spacing between the fibers becomes coarse, which causes problems in uniform heating, which is undesirable. In the present invention, the equivalent diameter is defined as the cross-sectional area of the fiber, the length, weight, and specific gravity. This is the value calculated from and converted into a diameter. The length of the conductive long fibers is 20 mm or more, preferably 20 to 500 mm, more preferably 30 to 2
00mm.

If it is shorter than the above lower limit, the heat generation rate becomes slow, which is not preferable.

In the present invention, "random" means that the conductive long fibers are arranged in a uniform manner without being biased in one direction or unevenly distributed such that the fibers are extremely concentrated, and furthermore, they are arranged so as to be three-dimensionally intertwined in multiple layers. Refers to the condition.

In the present invention, the conductive long fiber nonwoven fabric has a basis weight of the long fibers of 50 to 400 g/m", preferably 80 to 20 g/m".
0 g/m'' conductive long fibers may be formed into a nonwoven fabric together with thermoplastic resin fibers, or the conductive long fibers may be coated with a thermoplastic resin and the coated electrically conductive long fibers may be formed into a nonwoven fabric. If the basis weight of the formed nonwoven fabric is smaller than the lower limit of the above range, the heat generation rate will be slow, and if it is larger than the upper limit of the above range, overheating will occur, which is not preferable.

The amount of conductive long fibers in the nonwoven fabric when formed into a nonwoven fabric together with a thermoplastic resin is preferably 20 to 90% by weight. If the amount of conductive long fibers exceeds the upper limit of the above range, the conductive fibers will adhere to each other. When forming a nonwoven fabric by coating conductive fibers with a thermoplastic resin, it is difficult to maintain the shape of a nonwoven fabric. may be I as long as the conductive fibers can adhere to each other and maintain the shape as a nonwoven fabric.

The thermoplastic resin film on which the conductive long fiber nonwoven fabric is laminated has a thickness of 0.07 to 2.0 mm, preferably 0.1 to 2.0 mm.
It is 1.0 mm. If the thickness of the film exceeds the upper limit of the above range, the film becomes difficult to melt and is likely to cause poor adhesion, while if it is smaller than the lower limit of the above range, the adhesive airtightness will decrease and poor adhesion will likely occur, which is not preferred.

Thermoplastic resins used in the present invention include polyolefin resins, ethylene-vinyl acetate copolymers, ethylene-acrylic copolymers, ionomer resins, polyester resins, polyamide resins, polyimide resins, ABS resins, and ABS resins. Preferred examples include resins, polycarbonate resins, polyacetal resins, and the like.

It is preferable to select and use these resins as appropriate depending on the type of resin of the object to be joined.The object to be joined is a molded article of thermoplastic resin or thermosetting resin, wood, etc. .

Silane-based or titanium-based coupling agents may be added to thermoplastic resins used for nonwoven fabrics or films as necessary to prevent thermal deterioration of the resin and improve adhesion to metals. Fibers, fillers such as calcium carbonate and talc, pigments, etc. may be added.

The oscillation frequency used for high frequency induction heating is IMH2 or less,
100KHz or more, preferably 300-700K
It is Hz. This is to effectively generate high-frequency eddy currents in the conductive long fibers in the joining parts to efficiently heat a relatively wide area.

The present invention will be explained in more detail below based on examples. In the following examples, parts and percentages refer to parts by weight and percentages by weight, respectively, unless otherwise specified.

Example 1 150 parts of long iron fibers with an average length of 6 mm and an equivalent diameter of 35 μm manufactured by the steel wool method were opened in random directions using an air flow random web method, and then the average length was 6 mm.
50 parts of polypropylene fiber 11 (manufactured by Mitsui Petrochemical Co., Ltd., trade name J-600) with a diameter of 0.07 mm was added and entwined with long iron fibers to form a mat, and then heated at 230 to 250°C.
A nonwoven fabric was formed by hot pressing. This nonwoven fabric had a thickness of 0.2 mm, and the basis weight of the long iron fibers was 50 g/m''.

The obtained nonwoven fabric was cut to the size of the spiral coil, and polypropylene resin (manufactured by Mitsui Petrochemicals, trade name JH) was cut into pieces.
H-G) translucent molded plate (20 x 20 cm, thickness 2 mm)
) It was sandwiched between two sheets and placed on a high-frequency heating coil, and bonded using a high-frequency induction heating oscillator manufactured by Polymer Co., Ltd., UK-5KW).

Bonding conditions: Oscillation coil: spiral 3-5mm spacing, 6-tangle Oscillation frequency: 400KHz Distance from coil: 3mm Bonding pressure: 0.2kg/cm" Oscillation time: Bonding strength test shown in Table 1; 2 A 2.5 cm x 1.25 cm bonding member was sandwiched between two .5 crt + x 10 cm polypropylene resin adhesion test specimens, and high frequency induction heating bonding was performed under the same conditions as above, followed by 50 mm/min using a Tensilon type tensile tester.
The adhesive strength was measured at a speed of .

The test results are shown in Table 1. In Table 1, base material failure indicates that the resin of the molded product to be joined is fractured just before the bonded part. In other words, in the case of base material failure, the adhesive strength is the strength of the base material. shows.

Examples 2 to 6, Comparative Examples 1 to 4 Tests were conducted in the same manner as in the IMI except that the composition of the joining member was changed as shown in Table 1.

The test results are shown in Table 1.

The laminates etc. in Table 1 are as follows.

Lamination: T-die film (thickness 70 μm) of polypropylene (trade name: FC140, manufactured by Tokuyama Polypro Co., Ltd.) The nonwoven fabrics of Example 2 and Example 4 were laminated using a thermocompression roll.

Punched metal iron wheel: 0.2mm thick steel foil punched with a diameter of 2mm and a spacing of 2mm.

There are areas where fever does not occur.

Overheating and heat dispersion occur, and there are places where heat is generated close to decomposition of the resin.

Adhesive strength variation: Unbonded parts may occur due to heat generation variation, or adhesive strength may decrease due to resin decomposition due to excessive heat generation.

[Effects of the Invention] According to the present invention, a bonding device that has excellent heat generation efficiency regardless of the size of the bonding area, generates heat uniformly and evenly depending on the shape of the heating coil, and thereby achieves reliable bonding. A member is provided.

According to the present invention, a bonding method that does not cause edge effects, that is, so-called ambient heat generation, and does not cause uneven heat generation or abnormal heat generation within the bonding members, as occurs when conventional wire mesh or punched metal is used as the bonding member. A member is provided.

According to the invention, the conductive tool l! Since a joining member in which fibers are arranged three-dimensionally and randomly is provided, a remarkable effect is achieved in that abnormal heat generation due to fiber directionality and entanglement does not occur.

According to the present invention, since the joining member uses conductive long fibers, there is provided a joining member that has almost no difference in heat generation rate from a wire mesh.

Claims (1)

[Claims] 1. Conductive long fibers with an equivalent diameter of 10 to 100 μm and a length of 20 mm or more are formed together with a thermoplastic resin into a nonwoven fabric having a basis weight of 50 to 400 g/m^2. A joining member 2 made by high-frequency induction heating, characterized in that the joining member according to claim 1 is laminated on a thermoplastic resin film. 3. The joining member according to claim 1 or 2 is sandwiched between surfaces to be joined of objects to be joined, and then the joining member is heated by high frequency irradiation to melt the thermoplastic resin, and the joining member is placed between the surfaces of the objects to be joined. A joining method characterized by integrating.