JP2508163B2 - adhesive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Purpose of the invention [Industrial field of application] The present invention is for adhering plastic materials, wood, etc. in a short time in various industrial fields such as the automobile industry and the home appliance industry. The present invention relates to a high-frequency induction heating adhesive suitable for use in.

[Conventional technology]

The high-frequency induction heating bonding uses the heat loss based on the hysteresis loss of the conductor and / or the Joule effect due to the high-frequency induction, and uses a thermoplastic resin or a thermosetting resin as an adhesive to heat the adherend to thereby bond the adherend. It is a method of bonding and has the feature that high-speed bonding is possible.

As an adhesive for high-frequency induction heating bonding, there is a thermosetting resin such as an epoxy resin or a thermoplastic resin such as polypropylene in which fine spherical particles of a conductor such as iron, aluminum or copper are dispersed as a heating element. Kosho
In JP-A-53-21903, an adhesive using ferromagnetic metal spherical particles of 20 to 200 mesh as a heating element is disclosed in
In JP-A 60-130664, an adhesive using conductive short fibers as a heating element is proposed.

In high-frequency induction heating bonding, since the adhesive is internally heated, the heating efficiency is generally good, and it has the advantage that heating can be done in a short time as described above, but the heating efficiency depends on the material of the heating element, its shape and filling amount. That is, the amount of heat generated with respect to the applied high-frequency power is different, for example, even if the adhesive is filled with a heating element of the same kind of material in the same ratio to the resin,
When a short-fiber heating element is used, the heating efficiency is higher than when a particulate heating element is used.
130664).

However, for fibrous heating elements, it is not easy to mix the required amount uniformly with the resin in which it is to be dispersed because of its shape. Alternatively, there has been a problem that the dispersion blending process must be divided into multiple steps and repeated several times. Furthermore, when an adhesive using a fibrous heating element is molded and used by a method such as extrusion molding or injection molding, the fibers are oriented or unevenly distributed in the flow direction of the molten resin. Therefore, heat generation was likely to be non-uniform.

On the other hand, since the particulate heating element has a low heating efficiency as described above, a large amount of filling is required to obtain a high heat quantity, and as a result, the adhesive strength of the adhesive as a whole is unavoidably lowered.

[Problems to be solved by the invention]

The present invention provides an adhesive for high-frequency induction heating bonding which comprises a heating element having a high heat generation efficiency, which can be easily mixed with a resin for an adhesive, and can generate a large amount of heat with a small amount of mixing. .

(B) Configuration of the Invention [Means for Solving the Problems] The inventors of the present invention have made extensive studies as to the above problems, and as a result, by using a fine metal foil made of a ferromagnetic material as a heating element, spherical particles can be obtained. It has been found that a much higher heat generation efficiency can be obtained as compared with the case of using a heating element as the heating element, and has completed the present invention.

That is, the present invention, a metal foil made of a ferromagnetic material having the following shape, 70 per 100 parts by weight of the thermoplastic resin or thermosetting resin.
It is an adhesive for high-frequency induction heating, which is made by dispersing about 120 parts by weight.

 Minor axis length: 10 to 350 μm Major axis to minor axis ratio: 1 to 5 Thickness: 1 to 20 μm Minor axis to thickness ratio: 5 to 20 Hereinafter, the present invention will be described in detail.

[Metal foil]

The metal foil used in the present invention is a metal foil made of a ferromagnetic metal such as iron, cobalt, nickel or ferritic stainless steel, and has a minor axis of 10 to 350 μm and a major axis to minor axis ratio of 1 to 5. And a thickness of 1 to 20 μm and a ratio of the minor axis to the thickness of 5 to 20.

In the present invention, the heat generation efficiency can be remarkably improved by using the metal foil having the specified shape as the heating element for high frequency induction heating.

With regard to the shape of the metal foil, it is only necessary to satisfy the above conditions, and therefore, any metal foil having a shape such as a circular shape, an elliptical shape, a polygonal shape, or a shape that does not belong to any of them can be preferably used. .

Further, the metal foil is usually an aggregate of individual metal foils having various shapes, and the aggregate may contain a small amount of metal foil having a shape other than the scope of the present invention. In order to achieve, it is desirable that its content is less than 20% by weight.

In the present invention, the major axis and the minor axis representing the shape of the metal foil are the major axis having the longest length among the arbitrary diameters that divide the area of one sheet of metal foil into two, and the shortest length. Is a minor axis. It can be measured by observing with a microscope. The thickness of the metal foil is the average value of the thickness of 10 randomly extracted metal foils,
Here, the thickness of each metal foil is
Arithmetic mean value (Tmax + Tmin) of maximum thickness (hereinafter referred to as Tmax) and minimum thickness (hereinafter referred to as Tmin) obtained by measuring the thickness at the thickest and thinnest points
Defined to be / 2. This thickness is obtained by kneading 5 parts by weight of metal foil and 100 parts by weight of polypropylene, and extruding to form a tape with a thickness of 0.5 mm, and then cutting the tape vertically to obtain a cross section of a thin piece. It can be measured by observing with.

The short diameter of the metal foil needs to be 10 to 350 μm, and when the short diameter exceeds 350 μm, the cohesive force as an adhesive is reduced and sufficient adhesive strength cannot be obtained for the following reason. That is, the metal foil kneaded with the resin tends to be oriented parallel to the adhesive surface due to the flow of the molten resin when heated by high frequency induction, and the adhesive force between the metal foil and the resin is high. Since itself is not so strong, the cohesive force in the entire adhesive layer is reduced. On the other hand, the short diameter of the metal foil is 10 μm
If it is less than, as a result of increasing the content rate of fine powder metal foil,
This causes a decrease in heat generation efficiency. The preferred minor axis is 70 to 250 μm.

When the ratio of the long diameter to the short diameter of the metal foil exceeds 5, the shape becomes long and thin, which makes it difficult to uniformly disperse the resin in the resin. If the ratio of minor axis to thickness is less than 5, flatness is insufficient and high heat generation efficiency cannot be obtained. On the other hand, if it exceeds 20, the minor axis is 350 μm.
The cohesive force of the adhesive is reduced for the same reason as when it exceeds.

If the thickness of the metal foil is less than 1 μm, the metal foil tends to be crushed at the time of dispersion in the resin to form a fine powder having a short diameter of less than 10 μm.
The heat generation efficiency decreases, and even if it exceeds 20 μm, high heat generation efficiency cannot be obtained.

The metal foil is produced, for example, by mechanically hammering a metal powder having an average particle diameter of about 30 to 70 μm produced by a known method such as a spraying method or a reducing method, and spreading it by about 30 to 50 times, for example. It can be manufactured. The obtained metal foil may be sieved to obtain a metal foil having a desired short diameter, which may be used.

The amount of the metal foil to be mixed with the thermoplastic resin or the thermosetting resin should be 70 to 120 parts by weight of the metal foil per 100 parts by weight of the resin, and preferably 80 to 100 parts by weight of the metal foil per 100 parts by weight of the resin. It is a department. If the content of the metal foil is less than 70 parts by weight, a sufficient amount of heat generation cannot be obtained. On the other hand, if it exceeds 120 parts by weight, the cohesive force of the adhesive itself decreases and sufficient adhesive strength cannot be obtained.

[Thermoplastic resin and thermosetting resin]

As the thermoplastic resin used in the present invention, polyethylene, polyolefin such as polypropylene, polyester such as polyethylene terephthalate, ethylene-vinyl acetate copolymer, polyamide, acrylonitrile-butadiene-styrene copolymer and the like can be used, and thermosetting As the resin, epoxy resin, urethane resin, phenol resin, unsaturated polyester, etc. can be used.

The above resin can be appropriately selected and used according to the type of adherend, for example, when the adherend is polypropylene, polypropylene or a resin containing polypropylene as a main component is used as the resin for the adhesive. Generally, it is preferable to use the same resin as the material of the adherend. If one of the adherends is made of a material different from the other, the adhesive resin should be selected after considering the adhesiveness as appropriate.
For example, polyester is preferable for adhering a non-woven fabric of polyvinyl chloride and polyethylene terephthalate.

The metal foil and the adhesive resin are mixed with each other, for example, by using a twin-screw kneading extruder such as PCM-30 type of Ikegu Tekko Co., Ltd., for example, when the short fiber heating element and the resin are kneaded frequently. It can be easily performed without trouble such as clogging of the mesh attached between the screw and the die.

The kneading and extrusion conditions vary depending on the type of resin used,
When polypropylene is used as an example, a good adhesive in which the metal foil is evenly dispersed can be obtained under operating conditions of a kneading extrusion temperature of about 200 ° C. and an extrusion speed of about 30 kg / hour.

The conditions for high-frequency induction heating the adhesive of the present invention, the frequency is preferably 100KHz ~ 10MHz, the output is usually 5
An output of KW to 50KW is suitable. According to such conditions, it is usually within 10 seconds, and even if the adherend is a large object,
It can be glued within seconds.

Hereinafter, the present invention will be described more specifically by showing Examples and Comparative Examples.

[Examples and Comparative Examples]

The high frequency induction heating in each example has an output of 5KW and a frequency of 4.6MH.
z, oscillation time is 5 seconds, and adhesive strength is measured according to JIS K-68.
Tensile shear strength was measured according to 50.

Examples 1-2 and Comparative Examples 1-4 Polypropylene (E-250G, manufactured by Idemitsu Petrochemical Co., Ltd.)
100 parts by weight of pellets, average minor axis 150 μm, thickness 10 μm,
A twin-screw kneading extruder (PCM-3, manufactured by Ikegai Tekko Co., Ltd.) was used to prepare 100 parts by weight of iron foil having a ratio of major axis to minor axis of 2-3 and a ratio of minor axis to thickness of 15.
It was melt mixed according to 0) and pelletized. After making this pellet into a sheet with a thickness of 0.5 mm by hot pressing, cut this sheet with scissors into a size of 25 mm × 12.5 mm, and cut this into two glass fiber reinforced polypropylene sheets with a thickness of 5 mm (trade name: Azudel , Ube Nitto Kasei Co., Ltd. (hereinafter FR-PP
And abbreviated), and high-frequency induction heating adhesion was performed in a state of being held (Example 1).

As a result of measuring the tensile shear strength of the obtained adhesive, 91 kg
/ cm ² , and the breakage point was between the resin layer and the glass fiber layer in FR-PP.

Hereinafter, regarding the heating element and the usage amount thereof, high-frequency induction heating bonding was performed in the same manner as in Example 1 instead of the following, and the tensile shear strength of the obtained bonded body was measured.

Example 2: An iron foil having an average minor axis of 250 μm, a thickness of 10 μm, a major axis to minor axis ratio of 2 to 3, and a minor axis to thickness ratio of 20. 80 parts by weight are used per 100 parts by weight of resin.

Comparative Example 1: Iron powder having an average short diameter of 150 μm (mechanical crushed product). Use 100 parts by weight per 100 parts by weight of resin.

Comparative Example 2: The same iron foil as in Example 1. 1 per 100 parts by weight of resin
Use 50 parts by weight.

Comparative Example 3: The same iron foil as in Example 2. 5 per 100 parts by weight of resin
Use 0 parts by weight.

Comparative Example 4: Iron foil turned on to Japanese Industrial Standard 40 mesh sieve.
80 parts by weight are used per 100 parts by weight of resin.

The results of measuring the adhesive force in each example are shown in Table 1.

(C) Effect of the Invention According to the adhesive of the present invention, in high frequency induction heating,
Compared with conventional adhesives, high heat generation efficiency is obtained for the same applied power, rapid heating is possible in a short time, and the temperature distribution inside the adhesive is uniform, and the adhesive Since the cohesive force is large, a strong adhesive force can be obtained.

The adhesive of the present invention can be widely used in the fields of adhesion and welding in the automobile industry, the light electrical equipment industry, etc., and has a very great effect.

Claims (1)

(57) [Claims] 1. An adhesive for high-frequency induction heating bonding, which comprises 70 to 120 parts by weight of a metal foil made of a ferromagnetic material having the following shape dispersed in 100 parts by weight of a thermoplastic resin or a thermosetting resin. Minor axis length: 10 to 350 μm Major axis to minor axis ratio: 1 to 5 Thickness: 1 to 20 μm Minor axis to thickness ratio: 5 to 20