JPH07121555B2 - Resin material joining method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for joining resin materials, and in particular, a thermoplastic resin material (member) having a low adhesion property such as polypropylene with a high joining strength to a predetermined material. It relates to a method for advantageously joining.

(Prior Art and its Problems) Conventionally, a material obtained by joining a resin material such as an automobile interior material has been used for various purposes. For joining such a resin material and a mating material, In general, since adhesives and double-sided tapes are used, the joining force between these two members depends only on the adhesives and the double-sided tapes, and it is difficult to expect high adhesiveness. However, there is an inherent problem that peeling or the like is caused over time.

In addition, as one of the joining techniques for resin materials, a high-frequency welding method is known in which high-frequency induction heating is used to melt the resin material and join it with the mating material. In order to heat only the joint surface part,
It was difficult to apply such a high-frequency welding method to join materials required to be melted, and further materials such as polypropylene having a small loss coefficient.

Therefore, in Japanese Patent Publication No. 53-21903 and Japanese Patent Laid-Open No. 60-130664, etc., it is applied to a bonding surface of a predetermined resin material by using an adhesive obtained by mixing and dispersing conductive particles and conductive fibers. After that, a technique for joining with a mating material by high-frequency welding has been proposed.

However, in the method of using an adhesive containing such conductive particles or conductive fibers, high frequency induction heating is caused by the conductive material present in the adhesive layer formed on the bonding surface of the resin material. As a result, the adhesive layer portion can be heated, and effective bonding between the resin material and the mating material can be achieved.However, the conductor that contributes to high frequency heating is dispersed in the adhesive layer. However, the efficiency of high-frequency induction heating is not sufficient yet, and there are inherent problems such as the need to increase the mixing amount of conductors and lengthen the high-frequency induction heating time.

(Solution) Here, the present invention has been made in view of such circumstances, and is intended to solve the above-mentioned conventional problems, and is characterized in that at least one of them is thermoplastic. A method for joining a first member and a second member made of resin to each other, and an adhesive layer made of a thermoplastic adhesive having a predetermined thickness is provided on a joining surface of at least one of the first and second members. Then, on the surface of such an adhesive layer, a granular or foil-shaped or fibrous electric conductor heated to a temperature equal to or higher than the melting point of the thermoplastic adhesive is projected, and the projected portion of the adhesive layer surface is projected. The conductor is melted and adhered and fixed to the surface portion, and then the joining surfaces of the two members are overlapped with each other and high-frequency welding is performed, so that the first member and the second member are bonded via the adhesive layer. So that it can be joined to There is something I did.

Further, in the present invention, the amount of the conductor to be adhered and fixed: X (g / m ² ) is the amount of the thermoplastic adhesive used for forming the adhesive layer to be Y (g / m ^2). ), It is desirable that the following formula: X ≧ 0.1Y be satisfied.

(Operation / Effect) Therefore, according to the method of the present invention as described above, the powdery, granular, foil-shaped or fibrous conductor is not mixed with the adhesive as previously proposed, The surface of the adhesive layer having a predetermined thickness formed on the joint surface of the resin material (first member and / or second member) is melted and adhered and fixed thereto, and unevenly distributed on the surface portion of the adhesive layer. That is, since the high frequency induction heating is performed under the condition of being unevenly distributed in the vicinity of the interface with the mating material, the high frequency induction heating action is concentratedly applied to the unevenly distributed portion of the conductor. Therefore, since an effective heating action is induced and the high-frequency bonding can be efficiently performed, a high-frequency heating operation for a short time can be performed, and the amount of the conductor can be reduced, and it is high. Achieving a favorable bonding strength To get.

(Specific Description of Configuration) Incidentally, in the present invention, at least one of the first member and the second member to be joined is a resin material made of a thermoplastic resin, and also as a thermoplastic resin. , Various well-known resins are targeted, especially polypropylene (PP), polyethylene (P
E), polymethylpentene, polyvinyl chloride (PVC), polyamide (PAm; nylon), polyphenylene sulfide (PPS), polyether sulfide (PES), polycarbonate (PC), polyacetal (POM), polyether ether ketone (PEEK) ), Polyphenylene oxide (PPO) or the like, which is advantageously applied to a joining operation of materials (members) made of a thermoplastic resin having poor adhesion.

The mating material to which the resin material is joined may be the resin material of the same material or another resin material of different material, and it is also possible to join to a member made of a material such as wood or metal. Further, as the form of the resin material to be joined, generally, a sheet-shaped material having a predetermined thickness is targeted, but in addition, molded articles of various shapes, such as various shapes The same applies to joining.

Then, an appropriate thermoplastic adhesive is applied to the joining surface of at least one of the first member and the second member to be joined to form an adhesive layer having a predetermined thickness. It will be. As the thermoplastic adhesive, an adhesive made of a thermoplastic resin such as vinyl acetate-based, acrylic-based, ethylene copolymer-based, polyamide-based, polyester-based, polyurethane-based, etc. will be appropriately selected and used. . In addition, various known methods can be adopted for forming the adhesive layer made of such a thermoplastic adhesive.

Then, with respect to the adhesive layer thus formed on the joint surface of the predetermined member, further on the surface thereof, powder-shaped, foil-shaped or fibrous electric conductors are uniformly adhered and fixed, Thus, a layer in which the conductor is unevenly distributed is formed on the surface layer portion of the adhesive layer.

By the way, as a method for adhering and fixing the conductor on the surface of the adhesive layer, powder particles, foil pieces, fibers or the like of the conductor are free to move to cause uneven unevenness on the surface of the adhesive layer. In order to advantageously fix the electric conductor to the surface layer portion of the adhesive layer so as to prevent the occurrence of the above, particularly in the present invention, the electric conductor is formed of a thermoplastic resin that constitutes an adhesive layer formed on the joint surface. Heat to above the melting point of the adhesive,
A method of projecting onto the surface of such an adhesive layer and then melting the projected site on the surface of the adhesive layer to attach and fix the conductor to the surface site is adopted. As a method for heating the conductor, a method of heating the conductor with hot air or a flame spraying frame may be used.

In addition, the amount of conductor (Xg
/ m ² ) will be appropriately determined depending on the type and high-frequency welding conditions, etc., but in general, the following formula is used for the amount of the thermoplastic adhesive (Yg / m ² ) used for the joint surface: It is desirable to set it so as to satisfy X ≧ 0.1Y. In other words, the amount of conductor (X) can be reduced to 10% of the amount of adhesive used (Y), and high-frequency welding can be performed with such a small amount of conductor. This is because the conductor is unevenly distributed in the surface layer portion of the adhesive layer. On the other hand, if the amount of the conductor (X) is increased, the high frequency heating time can be shortened, but the upper limit is generally 50% or less, in other words, about 0.5Y or less. Becomes

Incidentally, as the electric conductor which is adhered and fixed to the surface of the adhesive layer as described above, as well known, for example,
It is made of a metal such as Fe, Co, Ni, or Cr, or an alloy thereof, or a conductive substance such as C. Such a conductive material is powdered by a known appropriate means to form a foil. Those which are made into small pieces (pieces), or made into fibers, or their analogues are used.

Then, the member obtained by adhering and fixing a predetermined electric conductor to the surface of the adhesive layer thus obtained is overlaid with the joint surface of the other member, and high-frequency welding is carried out in accordance with a conventional method. . It should be noted that, for this high-frequency welding, it is possible to adopt ordinary high-frequency welding conditions.For example, as the frequency, about 50 KHz to 10 MHz is adopted, and at that time, appropriate pressure is applied by air pressure or the like. The welding time (heating time) is about 1 to 10 seconds (depending on the bonding area, for example, about 3 to 4 kg / cm ² ).

Then, by such a high-frequency welding operation, at least one of the first member and the second member made of a thermoplastic resin, through the adhesive layer made to exist at their bonding interface, to the surface portion thereof. The efficient induction heating action of the adhered and fixed electric conductor enables quick and strong joining.

(Examples) Hereinafter, several examples of the present invention will be shown to clarify the present invention more specifically, but the present invention does not impose any restrictions due to the description of such examples. Needless to say, it is not something to receive.

In addition to the following embodiments, the present invention further includes various changes and modifications based on the knowledge of those skilled in the art, in addition to the above specific description, without departing from the spirit of the present invention. It should be understood that improvements and the like can be added.

Example 1 As the first member and the second member, resin sheets made of various thermoplastic resins were prepared, and joining of the resin sheets was tried in the combinations shown in Table 1 below.

As the thermoplastic adhesive, a polyolefin resin adhesive (Sumitomo 3M PPE-20, 3748-TC)
Using a standard calendering method, apply a thickness of 50 μm on the bonding surface of the resin sheets to be bonded and Y = 50
g / m ² ), the desired adhesive layer was formed. It should be noted that in Table 1, the adhesive-coated surface is shown as one-sided, in which the adhesive layer is formed only on the bonding surface of the first member (the upper one in the table).

Next, various electric conductors as shown in Table 1 are applied to the surface of the adhesive layer on the resin sheet on which the adhesive layer is formed according to the electric conductor attachment / fixing method shown in A to D below. did. The particle size of the powder used as the conductor is 100 mesh or less, and the foil has a thickness of:
The size was 10 μm or less, the maximum size was 1 mm, and the fiber was 10 μm in diameter × length: 0.5 mm. Further, in No. 10 in Table 1, no adhesive was applied or no conductor was applied, and in No. 11, only the silicon-based double-sided adhesive tape was used.

A: The conductor is attached and fixed to the surface of the thermoplastic resin adhesive layer with hot air at 300 ° C.

B: Apply a liquid polyolefin resin adhesive to the conductor,
Then, it is attached and fixed on the surface of the thermoplastic resin adhesive layer.

C: A conductor is dispersed (not fixed) on the surface of the thermoplastic resin adhesive layer.

D: A conductive resin paste adhesive (conductor content = 30% by weight) was applied to the bonding surface of the resin sheet.

Then, the first member (resin sheet) and the second member (resin sheet) treated as described above are overlapped at their joint surfaces, and using a normal high-frequency welding machine, output: 5 KW, High frequency welding was performed under the conditions of frequency: 5 MHz and oscillation time (welding time): 5 seconds.

As for various kinds of bonding resin sheets thus obtained,
The peeling test was performed according to -D-903, the adhesiveness in each case was evaluated, and the results are also shown in Table 1. Regarding the evaluation symbols in Table 1, ◯ indicates excellent, Δ indicates acceptable, and X indicates not.

As is clear from the results in Table 1, when only high-frequency welding was performed (No. 10), no joining was possible, and when the conventional double-sided adhesive tape was used for joining (No. 10). Even in 11), it was not possible to obtain a sufficient peeling load, and furthermore, conductors were simply dispersed on the adhesive surface (No. 12) or conductors were dispersed in the adhesive (No. .18), it was difficult to obtain a sufficient peeling load.

On the other hand, according to the present invention, in the state where the conductor is attached and fixed to the surface of the adhesive layer, the first member and the second member are overlapped and subjected to high frequency welding (No. 13 to 17)
In that case, since the conductor does not move,
A uniform and efficient high-frequency heating can be carried out at the surface portion of the adhesive layer, and the two members can be effectively joined, so that the peeling load is large, and therefore the peeling position is also one member (resin sheet). It was possible to obtain a bonding sheet with high bonding strength, which is the position.

Example 2 In the same manner as in Example 1, resin sheets of various combinations were joined as shown in Table 2 below.

The types and properties of the conductor, the coated surface of the adhesive, the heating method of the conductor, the melting point of the adhesive, the heating temperature of the conductor, and the projection method are as shown in Table 2 below.
The amount of projection (X) of the conductor was set to 20 g / m ^2, and the amount of application of the thermoplastic adhesive (Y) was set to 50 g / m ² . Furthermore,
The gas pressure for pneumatic and thermal spraying was 1.0 kgf / cm ² . Two types of polyolefin-based thermoplastic adhesives are used, and those with a melting point of 120 ° C are PPE-20: 3748-T.
C (manufactured by Sumitomo 3M Limited) with a melting point of 135
The one at ℃ was Admer QE050 (manufactured by Mitsui Petrochemical Industry Co., Ltd.).

As is clear from Table 2, when the conductor is adhered and fixed to the surface of the adhesive layer (No. 23 to 29),
We were able to obtain a bonding sheet with high bonding strength, but when a conductor was applied to the surface of the adhesive layer, but the conductor was not fixed at all (No. 20) or in a fixed state. If the value is not sufficient (Nos. 21 and 22), a sufficient peeling load cannot be obtained, and the peeling position becomes an interface, resulting in low bonding strength.

Example 3 The resin sheets of various combinations shown in Table 3 below were joined in the same manner as in the above Example, and the results are also shown in Table 3 below.

In this example, the projection amount (X) of the conductor and the application amount (Y) of the adhesive were also changed variously. In addition, the type and properties of the conductor, the coated surface of the adhesive, the coating amount of the adhesive, the heating method of the conductor, the melting point of the adhesive, the heating temperature of the conductor, the projection method, the projection amount of the conductor are all Also, the following third
As shown in the table.

As is clear from Table 3, a sufficient effect cannot be expected when the electric conductor is simply dispersed on the surface of the adhesive layer, and when the amount of the electric conductor used is too small, the effect is insufficient. It is difficult to fully exhibit the high-frequency induction heating action in a short time, and it is recognized that the peeling load and eventually the bonding strength are reduced even when the conductor is not securely fixed. Of.

On the other hand, as shown in No. 33 to 39, on the surface of the adhesive layer formed on the bonding surface of the resin sheet, when the conductor is securely fixed in a sufficient amount, It is recognized that a large peeling load can be obtained, and the peeling position is located on either one of the resin sheet portions, so that a bonding sheet with high bonding strength can be obtained.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Setsumi Yoshida 2-27-16 Haruoka, Chikusa-ku, Nagoya-shi, Aichi Yoshida Chemical Co., Ltd. (56) References JP-A-50-50738 (JP, A) USA Patent 3461014 (US, A) International Publication 87/74 (WO, A)

Claims (2)

[Claims] 1. A method for joining a first member and a second member, at least one of which is made of a thermoplastic resin, to form a thermoplastic adhesive on the joint surface of at least one of the first and second members. After forming an adhesive layer made of an agent to a predetermined thickness, a powdery, granular, foil-like or fibrous conductor heated to a temperature equal to or higher than the melting point of the thermoplastic adhesive is projected on the surface of the adhesive layer. , The projection portion of the adhesive layer surface is melted to adhere and fix the conductor to the surface portion, and then,
A method for joining resin materials, characterized in that the first member and the second member are joined via the adhesive layer by superposing the joining surfaces of the two members and performing high-frequency welding. 2. The amount of the conductive material to be adhered and fixed: X (g /
m ² ) and the amount of the thermoplastic adhesive used to form the adhesive layer: Y (g / m ² ) satisfy the following formula: X ≧ 0.1Y. The method of joining according to item.