JPS62132983A - Adhesive for high-frequency induction heating - Google Patents

Abstract

PURPOSE:To provide the titled adhesive produced by uniformly dispersing a heat-generating material composed of magnetic metal short fibers and metallic powder in a resin, having excellent rate of bonding, adhesion uniformity and adhesive strength and capable of improving the flexibility for the selection of the frequency and coil form of a high-frequency heater used in the bonding with the adhesive. CONSTITUTION:The objective adhesive can be produced by compounding (A) 100pts.(wt.) of a thermoplastic or a thermosetting resin with (B) 5-100pts. of magnetic metal short fibers having a length/diameter ratio of 10-100 and (C) 10-200pts. of metallic powder finer than 50 mesh.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to improvements in high frequency induction heating type adhesives. In particular, the present invention relates to improvements that improve bonding speed, bonding uniformity, and bonding strength, and further relates to improvements that increase the degree of freedom in selecting the frequency of a high-frequency heating device used for bonding and the degree of freedom in selecting the coil shape.

[Conventional technology]

Several types of high-frequency induction heating adhesives have already been proposed, and one of the representative ones is a high-frequency induction heating adhesive in which the heating element is ferromagnetic particles of 20 to 200 meshes (Japanese Patent Publication No. 53
-21903), and another representative one is a high-frequency induction heating type adhesive (Japanese Patent Application Laid-Open No. 80-130F184) in which the heating element is a conductive fiber.

All of these typical high-frequency induction heating adhesives are
This adhesive is made by uniformly dispersing these heating elements in a resin, and can achieve good adhesion using a high-frequency induction heating method.

[Problem that the invention seeks to solve]

For high-frequency induction heating adhesives that use ferromagnetic particles as a heating element, or high-frequency induction heating adhesives that use non-magnetic conductive fibers, high-frequency induction heating adhesives that use magnetic short metal fibers. Compared to adhesives, the heating efficiency of high-frequency waves is poor. Therefore, in order to perform short-time bonding on the order of seconds, which is a characteristic of high-frequency induction bonding, it is necessary to increase the heating efficiency. The frequency needed to be higher than IM)Iz was necessary. In high-frequency induction heating devices of 1 MHz or higher, compared to devices of 20 to 400 KHz commonly used for metal hardening, etc., the impedance of the circuit including the heating coil is larger, making it difficult for current to flow. In order to obtain the output of , it was necessary to increase the voltage by that much. Therefore, when comparing high-frequency induction heating devices in the KHz band and MHz band with the same output, the voltage used in the MHz band device is higher, so sparks and leakage are more likely to occur, and the risk of electric shock is also greater. Furthermore, in the MHz band, the heating depth by high-frequency induction heating becomes shallow due to the skin effect, so it is necessary to make the distance between the adhesive and the heating coil extremely close, which is a major constraint when designing the heating coil. was there'.

When magnetic short metal fibers are used as the heating element, the heating efficiency is higher than in the above case, and heating is possible even in the K)Hz band. However, from the point of view of processing such as extrusion molding on a practical scale, it is difficult to disperse and fill adhesives that use short magnetic metal fibers as heating elements in resin at a high density compared to particulate heating elements. For example, when iron fiber is used as magnetic metal short fiber, resin 10
The limit was to disperse and fill 100 to 120 parts by weight of iron wire m per 0 parts by weight. High-frequency induction heating adhesives containing magnetic short metal fibers can generate enough heat to melt the resin even when the filling rate of the magnetic short metal fibers is about 1/10 of the particles. If the temperature distribution of the layer becomes uneven and the entire layer is heated until it melts, the temperature near the magnetic metal short fibers will reach the point where the resin decomposes, and the resin layer will foam, carbonize, etc. and the adhesive strength will decrease. There was a problem.

[Means for solving problems]

The present invention is operationally safe, and can also be heated using a KHz band high-frequency heating device with a large degree of freedom in device design.The present invention is a heat generating device that is characterized by being able to heat evenly even if the packing density of the heating element is small. In order to give concrete form to the idea that the above drawbacks could be overcome by developing a high-frequency induction heating type adhesive containing heating elements, we conducted numerous experiments with various heating element compositions, and examined the results. The result is completed,
The high frequency induction heating adhesive according to the present invention is a heating element of a high frequency induction heating adhesive in which a heating element made of magnetic or conductive strips is uniformly dispersed in a thermoplastic or thermosetting resin. For 100 parts by weight of resin, 5 to 10 parts by weight of magnetic short metal fibers having a length to diameter ratio of 10 to 100 and 10 to 200 parts by weight of metal powder having a mesh size of 50 or less are used. .

[Effect]

The reason why short metal fibers are effective as heating elements in high-frequency induction heating adhesives is thought to be that, unlike granular TA fibers, the TA fibers dispersed in the resin come into contact with each other, generating heat due to eddy current loss. Ru.

Furthermore, among these, magnetic short metal fibers have particularly high heating efficiency and can be heated even in the KHz band, which is thought to be due to the mutual utilization of eddy lightning loss and hysteresis loss.

Furthermore, the effect of mixing metal powder is to make the temperature distribution of the adhesive layer uniform, and it is thought that this is based on the fact that metal powder has higher thermal conductivity than resin.

Hereinafter, each component of the high frequency induction heating type adhesive according to the present invention will be explained in detail.

(a) Magnetic metal short fibers Examples of the magnetic metal short fiber materials used in the present invention include iron, magnetic alloys, and ferritic stainless steel such as 5O8430. Ferritic stainless steel is preferred, and the ratio of the length of the conductive fiber to its equivalent diameter (hereinafter referred to as aspect ratio) must be in the range of 10 to 100. The larger the aspect ratio, the higher the probability that mm will touch each other, which makes it easier for eddy currents to occur and increases heating efficiency. However, when am is extruded into resin,
They become like fluff and become entangled with each other, making it difficult to uniformly disperse them in the resin.

On the other hand, if the aspect ratio is small, dispersion is easy, but the heating efficiency is greatly reduced because it becomes more like a powder. Therefore, in the present invention, it is necessary that the aspect ratio is in the range of 10 to 100, and particularly preferably in the range of 30 to 70.

Here, the equivalent diameter is a converted value expressed by the following formula.

however, D is the diameter; S is the cross-sectional area.

Further, it is preferable that the magnetic short metal fibers have a length of 1 to 10 m and a diameter of 40 to 120 mm, and for such purposes, short metal fibers manufactured using the chatter vibration cutting method are inexpensive and easy to use. This is preferable because it is available, and the amount of magnetic short metal fibers to be filled in the resin is 5 parts by weight or more based on 100 parts by weight of the resin, as described above.
Sufficient calorific value is obtained to melt the resin, while
Since it is difficult to uniformly disperse an amount exceeding 100 parts by weight, a suitable range is 5 to 100 parts by weight.

In addition, the ratio of magnetic short metal fibers to the metal powder described below,
If there are too many short fibers, the amount of metal powder that should contribute to uniform temperature distribution will be insufficient, making the temperature distribution likely to become uneven.On the other hand, if there are too few short fibers, the shielding effect of the metal powder will cause the temperature distribution to become uneven. This prevents the magnetic force from reaching the short fibers and prevents them from generating heat. Therefore, the weight ratio of short fibers and metal powder was set to 5:
A range of 1-1:1 is desirable.

(b) Metal powder The purpose of the metal powder used in the present invention is to make the temperature distribution of the adhesive layer uniform through its thermal conductivity, so it has a large specific surface area (surface grain per unit weight). Therefore, it is necessary to have a fine powder of 50 meshes or less, and preferably a fine powder of 15G meshes or less.

Iron powder is suitable for this purpose.

7 such as aluminum powder, stainless steel powder, ferrite powder, etc.
Tomize powder is relatively inexpensive and suitable.

Similarly, the amount of metal powder to be filled is required to be at least 10 parts by weight per 100 parts by weight of the resin in order to make the temperature distribution of the adhesive layer uniform. There is a limit in the molding process, and in order not to reduce the cohesive force of the adhesive layer, the volume ratio is preferably within 20%, and even if iron powder is a metal with a large specific gravity, it is within 200 parts by weight. It is preferable. Therefore, it is necessary that the metal powder be used in an amount of 10 to 200 parts by weight per 100 parts by weight of the resin.

〔Example〕

EXAMPLES Hereinafter, examples will be described together with corresponding comparative examples, and the present invention will be further described. The adhesive strength of each piece is a value measured according to JIS K-8850 using a test piece measuring 25+++m x 100m.

Actual jL example”.

First, as an adhesive, Pelleft 100, a resin made of a blend of mylenated modified polypropylene and polypropylene, was used.
5US43 manufactured by Juyabe and chatter vibration cutting method
80 parts by weight of magnetic metal fibers ([10 terminal diameter x 2 mm)] and aluminum atomized powder (350 mesh,
(manufactured by Metal Foil and Powder Industry Co., Ltd.) was melt-kneaded and extruded using a twin-screw extrusion machine (manufactured by Ikegai Tekko Co., Ltd., model P CM-30) to create adhesive pellets. In this case, the resin and aluminum powder were blended before molding, and the mixed portion was placed in the extruder hopper. The short stainless steel fibers were fed into the vent hole in the center of the extruder cylinder using a quantitative feeding device. The molding temperature is as follows.

a. Cylinder temperature: 170-230℃ b. Adapter temperature: 230℃ C. Die temperature: 220℃ Using a heating press, press this pellet to 200"C12
It was molded into a sheet with a thickness of 0.7 mm at kg/cra2. This sheet was cut to a size of 25 to 12.5 mm with scissors, sandwiched between two test pieces of glass fiber reinforced polypropylene (manufactured by Idemitsu Petrochemical Co., Ltd., X Sheet), adhered by high frequency induction heating, and subjected to tensile shearing. I created a trial piece. The high frequency power source has an output of 4KW and a frequency of 400KH2 or 4MHz, and heating coil 1, lo is a pressurized hairpin type coil with a heating surface size of 12.5 x 5hm as shown in Figure 1. In Figure 0, 2 is a It is an air cylinder, 3 is a coil connection lead wire, 4 is a test piece, and 5 is an adhesive.

For the adhesive test pieces, tensile shear strength was measured and fracture locations were observed using a Strograph T-type testing machine (Top part manufactured by Toyo Seiki).

In Examples 1 to 7 and Comparative Examples 1 to 5 below, adhesive pellets and sheets were molded in the same manner to create tensile shear test pieces. In Example 8, a similar test piece was prepared by sandwiching a heat-curing paste adhesive made of an epoxy resin and a curing agent between two test pieces and curing it by high-frequency induction heating. The material, adhesive composition, bonding conditions, bonding strength, and location of failure of these test pieces are listed in Tables 1 and 2 below.

1st surface layer test piece vclw material Resin No. (test piece) Material
Parts by weight Example 1 Glass lam reinforced pp 1) Modified polypropylene 2) Lo.

Example 2 tt tt
//Example 3 //
// //Example 4 //
// /1 Example 5 Polyethylene Modified polyethylene 5) +90 Example 13
// --tt //Example 7
Wood (beech)/'Copolymerized nylon 7) 1o.

Example 8 FRP (polyester) epoxy”
100 Comparative Example 1 Glass fiber reinforced pp1) Modified polypropylene 2) 100 Comparative Example 2 // -//
tt Comparative Example 3 tt
// // Comparative example 4 〃
〃 〃Comparative example 5 //
tt // Adhesive composition Magnetic metal powder Material
Weight part Material
mu part stainless steel am3) 8G aluminum powder 35G mesh" 30//
/I /l

/1 stainless steel m m3)40 //
tt〃〃〃〃 Stainless steel fiber 3) 4G Stainless steel powder 200 mesh 8) 50〃〃〃〃 Iron m! 18) 8G aluminum powder 350 meters? Six 03G stainless fiber! l 3) 40
// ,.

Stainless fiber 3) 80 -〃
40 □-Iron powder 200
10) 150 single gg2 table High Frequency Oscillation time Adhesive strength No. Frequency x Output (sec) (Kg/am2) Example 1 48) 12X 4KW 5
79 Example 2 400KHzX 4KW
25 81 Example 3 4MHz
678 Example 4 400KHzX 4-4
083 Example 5 4MHzX 4KW
5 42 Example 6 400KHz
3541 Example 74 with HzX4
544 Example 8 400KHzX O, 1~0
．． 3KW 90 7B Comparative Example 1 4M) Iz
X 4KW 5 41 Comparative example 2
// 8 37 Comparative Example 3
tt 120 - Comparative Example 4 400KHzX 4 KW 12
0 - Comparative Example 5 4M)lzX4KW
120 - Adhesion test breakage location Preparation
Consideration Test piece surface fracture (between resin and glass fiber layer) Part of test piece fracture interface/Wood surface fracture (interface between adhesive and test piece) Interfacial interface, partial surface fracture Insufficient melting of adhesive 1 No heat generation Uniform interface The adhesive layer decomposes,
Supplementary explanation of materials listed in Tables 1 and 2 that are brittle and lack heat generation, do not generate enough heat to melt and bond, and do not generate enough heat to form melt bond.

l) Glass fiber reinforced PP X sheet made by Idemitsu Petrochemical ■, 3-layer thick.

2) Blend of 20 parts of modified polypropylene maleated modified polypropylene (copolymer of maleic anhydride/propylene = 1O/90) and 80 parts of polypropylene (melt index 5) 3) 5US430, equivalent by stainless steel fiber chatter vibration cutting method Diameter 804
m, length 2 am.

4) Aluminum powder Aluminum atomized powder 3 made by Fukuyama Metal Foil Powder Industry ■
50 meters.

5) Modified polyethylene Maleated modified polypropylene (copolymer of maleic anhydride/propylene = 10/90) 10 parts and polyethylene (melt index 2) Q^☆ma n-i 1.
・Noshi Co., Ltd. 6) Stainless steel powder manufactured by Fukuyama Metal Foil Powder Industry ■ 5US304 atomized powder 20
0 mesh.

7) Copolymerized nylon plate Φpon GmbH (West Germany) Bratamid H10
5 (product name).

8) Iron fiber Equivalent diameter 80ILm by chatter vibration cutting method.

Length: 311 Is 9) Epoxy oil shell made of epoxy ■ Epicoat 828 100 parts by weight, isophthalic acid dihydrazide 15 weight ff1ffll,
2 parts by weight of 2MZ-Azine (trade name) manufactured by Shikoku Kasei ■.

10) Reduced iron powder made by Yahagi Steel ■ 200 mesh, amorphous particle aspect ratio 1-5° 11) 6/4 brass (equivalent diameter 80!) made by Shinchu fiber chatter vibration cutting method.
m, length 3 mm).

In Examples 1 to 4, glass fiber reinforced polypropylene was bonded with a thermoplastic adhesive according to the present invention, and the high frequency E wave number used in Example 1 was 4 MHz, and the high frequency E wave number used in Example 2 was is 400
It is KHz. In the case of 400 KHz, the heating efficiency is poor compared to 4 MHz, and a long heating time is required, but high frequency induction bonding is possible.

Example 3.4 shows the filling amount of magnetic short metal fibers compared to Example 1.2.
Although the heating time is longer than in Example 1.2, adhesion is possible.

In Examples 1 to 4, the adhesive strength was good, and the results of the tensile shear test showed that the fracture occurred between the resin layer on the surface of the test piece and the internal glass fiber layer, and so-called material fracture occurred. Recognized.

Examples 5.6 are the adhesion of polyethylene test pieces and similarly good adhesion is obtained.

Example 7 is an example in which the present invention is applied to bonding wood.

Example 8 is an example in which the present invention is applied to a thermosetting adhesive, in which FRP (glass fiber reinforced unsaturated polyester resin) is bonded with an epoxy adhesive. In this case, rapid heating will cause decomposition and foaming of the adhesive resin, and the curing reaction will take some time.
In order to maintain the temperature between 200 and 220℃, the output is set to 0.1
It is variable and controlled in the range of ~G, 3KW.

Comparative Example 1.2 uses only magnetic short metal fibers as a heating element. In Comparative Example 1, heat generation is quick and adhesion is possible, but after adhesion, many fractures occur at the interface between the adhesive and the test piece, and the adhesion strength is weak compared to the example, as a result of observing the interface. The cause of this poor adhesion is thought to be that heat generation at the adhesive interface was not uniform and melting was insufficient.

In Comparative Example 2, as a result of reducing the filling amount of magnetic short metal fibers to half that of Comparative Example 1, bonding is not possible unless the heating time is extended, but this makes the temperature distribution of the adhesive layer even more uneven, and the fibers The resin in the vicinity had thermally decomposed, becoming wax-like and brittle.

Comparative Examples 3 to 5 used iron atomized powder, which is a magnetic powder, or Shinchu staple fiber, which is a non-magnetic fiber, as a heating element, but even with high-frequency 1-induction heating for 120 seconds, melt adhesion was achieved. No fever was observed. As for the cause.

This is thought to be because the hairbin type coil used in FIG. 1 can provide stable contact pressure, but its heating efficiency is poor for these heating elements.

〔Effect of the invention〕

As explained above, the high-frequency induction heating type adhesive according to the present invention has, as its heating element, 100 parts by weight of resin,
Magnetic short metal fiber 5 with a length to diameter ratio of to-100
~10 heavy parts and 50 mesh or less metal powder 10~200
Since the weight parts are used, it is safe to operate, and high-frequency induction heating bonding is possible even with KHz-band high-frequency heating equipment, which has a large degree of freedom in equipment design, and the packing density of the heating element is small. Even high-frequency induction heating bonding is possible. In other words, high-frequency induction heating enables rapid and uniform heating and provides high adhesive strength. Furthermore, the degree of freedom in selecting the frequency of the high-frequency induction heating device and the shape of the coil is increased, and the range to which high-frequency induction heating bonding can be applied is further expanded.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a hairpin type coil used in the present invention and a heating adhesive using this coil. 1.1'... Heating coil, 2... Air cylinder, 3... Coil connection '- lead wire. 4...Test piece, 5...φ adhesive.

Claims (1)

[Scope of Claims] A high-frequency induction heating adhesive in which a heating element made of magnetic or conductive strips is uniformly dispersed in a thermoplastic or thermosetting resin, wherein the heating element comprises 100 parts by weight of the resin. 5 to 10 magnetic short metal fibers having a length-to-diameter ratio of 10 to 100.
1. A high-frequency induction heating type adhesive comprising: 0 parts by weight and 10 to 200 parts by weight of metal powder having a size of 50 mesh or less.