JPS6025232B2 - Sealing material for spot welding with vibration damping properties - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sealing material for spot welding that is inserted as a sealing material between two metal plates when spot welding the same.

Conventionally, when spot welding two metal plates, self-fusing butyl rubber tape, adhesive, sealant, etc. have been used to make the welded part waterproof, anticorrosive, and vibration proof. In this case, if these sealants were present in the parts of the two metal plates to be spot welded, welding would be impossible due to the insulating properties of the sealants. Therefore, it was necessary to perform welding at different locations between the seals and welds, or to apply sealants after welding.

On the other hand, sheets that have a pressure-sensitive conductive function by blending metal (including alloys of metals) particles into a rubber-like elastic body are also known.

When pressure is applied perpendicularly to the sheet surface of this pressure-sensitive conductive sheet material, a rapid drop in electrical resistance occurs due to the contact action of the blended metal particles. Therefore, a sheet is inserted as a sealing material at the welding point of two metal plates to be spot welded, and the sheet is inserted from the top of the metal plates.
Spot welding can be performed through this seal material. That is, during spot welding, pressure is applied to the sealing material sandwiched between two metal plates through the metal plates by the cylinder pressure of the spot welding machine, resulting in a sudden drop in resistance. As a result, a current flows between the two metal slopes, making spot welding possible. However, in the case of a sheet containing pure metal or metal alloy particles, the metal particles on the surface will rust, impairing the electrical conductivity of the sheet, corroding the sealed metal plate, and changing the appearance. It has the disadvantage of impairing the

On the other hand, it is also desired that the sealing material for spot welding has vibration damping properties. This damping property has the effect of attenuating and muffling the vibrations and noise of metal plates, etc. Conventionally, this type of damping material uses a composition made of a rubber or plastic polymer mixed with an inorganic filler, etc., but the damping effect of these damping material compositions depends on the polymer itself. Since the loss coefficient was small, even if the amount of filler was increased, the damping effect did not improve much. There was also a limit to the amount of filler added. On the other hand, as mentioned above, in products containing metal particles, there is a problem with the compatibility between the metal and the rubber-like elastic body, in addition to correcting rust as described above, and it is difficult to obtain uniform dispersion of the metal particles. There was a risk that variations would occur in the damping effect of the sheet material. Furthermore, high filling of metal particles softens the rubber-like elastic body, making it extremely difficult to process the sheet and at the same time making it difficult to obtain sufficient elasticity. The present invention solves these problems at once, and is characterized by using metal silicon alloy fine powder instead of metal particles.

That is, when a metal silicon alloy powder is used, unlike metal, it does not rust, so the above-mentioned drawbacks associated with the formation of rust can be overcome.

Further, since metal alloys have an affinity for rubber-like elastic bodies, high filling (high density packing) is possible, and uniform dispersion can be obtained. Therefore, it is possible to overcome the drawbacks of using conventional inorganic fillers and metal powders, and to create a sheet that has a large apparent specific gravity and does not impair the desired elasticity of the rubber-like elastic body, which is difficult to process. There is also the advantage that it can be manufactured without The vibration-damping spot welding seal material of the present invention has a large apparent specific gravity, preferably 2.5 or more, so that even a thin sheet-like material can exhibit a damping vibration damping effect with a large loss coefficient.

The loss factor of the rubber compounded composition used in the present invention increases as the filling amount of metal silicon alloy particles increases, but when increasing the apparent specific gravity, the rubber sheet material is not damaged compared to the rubbery elastic body. It is desirable to select the amount, type of metal silicon alloy particles, and particle size of metal silicon alloy particles depending on the application. However, usually, metal silicon alloy particles of 15 to 2000 µm containing at least 5% of silicon are blended in an amount of 2 to 70% to the rubber-like elastic body, and the apparent specific gravity of the resulting rubber composition is 2.5. It is desirable to have the above.

The sealing material of the present invention can be in various forms, such as a sheet made of such a rubber compound composition, a sheet with an adhesive layer applied thereto, or a combination of this sheet with a woven fabric or non-woven fabric support. be able to. For example, as shown in Figure 1,
A pressure-sensitive conductive adhesive layer 1 may be uniformly applied to an unvulcanized sheet-like base material 2 made of a pressure-sensitive conductive rubber-like elastic material, or a woven or non-woven fabric 3 may be applied as shown in FIG. A sheet-like base material 2 may be provided on both sides of which a pressure-sensitive conductive rubber compound can be uniformly applied, and a pressure-sensitive conductive adhesive layer 1 may be applied to one or both surfaces thereof. To describe the specific materials of the pressure-sensitive conductive compound composition used in the present invention, examples of rubber-like elastic bodies include natural rubber (NR), isoprene rubber (I
R), styrene butadiene rubber (SBR), butadiene rubber (BR), chloroprene rubber (CR), nitrile rubber (NBR), butyl rubber (11R), ethylene propylene rubber (EPT), 1,2 polybutadiene (RB) ~
Examples include rubbers such as urethane rubber and chlorinated polyethylene. Metal silicon alloys to be blended (dispersed filling) into rubber are alloys of silicon with gold, silver, copper, aluminum, iron, chromium, manganese, zinc, etc., and silicon alloys represented by silicon-containing stainless steel. 15mm~2000
Use particles with the same particle size.

The blending amount is generally 2 to 70% based on the rubber. In the example shown in FIG. 1, this pressure-sensitive conductive rubber-like elastic material compound is formed into a sheet of uniform thickness, and in a vulcanized state, it is made into a spot acid-soluble (pressure-sensitive conductive) sheet 2. It is a village.

Next, a pressure-sensitive conductive adhesive layer 1 is applied to both sides or one side of this sheet. Metal-silicon alloy particles of an alloy of silicon with gold, silver, copper, aluminum, iron, etc., having the following properties, are uniformly dispersed in an amount of 1 to 10%. In addition, in the case of the embodiment shown in Fig. 2, cotton,
A support 3 made of woven fabric or non-woven fabric such as nylon, pinylon, polyester, etc. is coated with the above-mentioned self-pressure-sensitive conductive rubber composition evenly on both sides and impregnated, and in an unadded state, it is suitable for spot welding. It is used as a (pressure conductive) sheet base material.

Next, the pressure-sensitive conductive adhesive layer 1 is coated on one or both sides of this sheet. The resistance of such spot weldable sealing materials decreases when pressure is applied during spot welding, and the resistance value changes rapidly from 1-pin when no pressure is applied to less than 100-thick when pressurized.

Example 1 A rubber-like elastic body mainly made of isoprene rubber was coated with 70r~
A blended composition containing 40% by volume of ferrosilicon powder having a particle size distribution of 300 mm and a silicon content of 50% was uniformly sheeted to a finished thickness of 0.3 mm.

Next, a rubber adhesive containing 4% by volume of ferrosilicon powder with a particle size distribution of 75 to 150 mm and a silicon content of 50% is applied uniformly to one side of the rubber sheet to a thickness of 0.05 mm. A single-sided adhesive rubber tape with a thickness of 0.35 ribs was obtained. Using the rubber tape obtained in this way, pressurize (
Pk9/enemy) is added to obtain the volume resistivity after sand (pv○
- arc) was measured (Enokiyama constant temperature 20°C), and the obtained results are shown in Figure 3. From FIG. 3, it was shown that when the applied pressure exceeds 16XQ/, the resistance value becomes 0.50 or less, and excellent conductivity is obtained. This spot welding sealing material was sandwiched between two iron plates with a thickness of 1 rib and 5 bars, and spot welding was performed under welding conditions of a rated primary voltage of 480 V and a maximum secondary short circuit current of 25,000 A. At this time, the pressure during spot welding is 160k9/ground, and the longitudinal resistance value of the seal tape for spot welding in this state is less than 0.10, which is a condition that allows spot welding by applying current. I am fully satisfied. In addition, in order to examine the damping effect of this spot sealing material, the loss elastic modulus was measured for the spot welding with the above spot sealing material and the spot welding without the spot sealing material, and the results are shown below. Shown below.

Table 1 Loss Modulus As is clear from Table 1, the spot welding seal material of the present invention was found to have an excellent vibration damping effect.

Example 2 A blended composition in which 60% by volume of silicon-aluminum alloy (Silumin) fine powder with a particle size distribution of 30 μm or less and a silicon content of 14% was blended with a rubber-like elastic body that is a blend of EPT and SBR was used to create a composite composition with a total finishing thickness of 60% by volume. Sheeting was carried out uniformly on the 0.5 side.

Next, a synthetic rubber adhesive containing 6% by volume of silicon-aluminum alloy textured powder with a particle size distribution of 30 mm or less and a silicon content of 14% is applied to this rubber sheet uniformly to a thickness of 0.05 mm. was applied on one side to obtain a single-sided adhesive tape with a thickness of 0.55 mm. The rubber tape obtained in this way has a thickness of 2.5 mm.
It was sandwiched between two aluminum plates, one for the side and the other for the 6th rail, and spot welded under ship welding conditions with a rated primary voltage of 480y and a maximum secondary short circuit current of 7600. When spot welding was performed with this tape in between, the spot weld strength was no different from that without the spot tape. The measured values are shown in the table below. Table 2-1 Spot welding strength Injected pressure 400K Tip diameter 25 ribs As is clear from Table 2-1, it was found that the spot welding strength was not affected by the spot welding sealing tape of the present invention. It was done.

In addition, in order to see the vibration damping effect of this spot seal material,
The table below shows the results of measuring the loss modulus of an aluminum plate spot welded with the above spot sealant and an aluminum plate spot welded without the spot sealant. Table 2-2 Loss Modulus As is clear from Table 2-2, the spot welding sealing material of the present invention was found to have an excellent vibration damping effect.

Example 3 A blended composition in which 35% by volume of silicon-containing stainless steel alloy fine powder with a particle size of 5% or less and a particle size of 40F or less was blended with self-crosslinking acrylate latex was prepared as a polyester having a basis weight of 50F/L. Both sides of the nonwoven fabric were soaked in a coating chamber, dried and then heat treated at 120°C for 30 minutes to a thickness of 0.2
5 uniform sheets were obtained.

On both sides of this sheet, silicon-containing stainless steel alloy fine powder with a particle size of 40 or less and a silicon content of 5% is applied at a volume ratio of 4%.
Apply the acrylic adhesive to be mixed evenly to a thickness of 0.04, and A double-sided adhesive tape with a thickness on the uneven side was obtained. The tape obtained in this way was sandwiched between two stainless steel plates of 1 willow thickness, and the rated primary voltage was 200 V and the maximum secondary short circuit current was 80 V.
Spot welding was performed under 0M welding conditions. Using a sample spot-welded with this tape in between, water pressure was applied from one side and the sealing properties of this tape were observed. As a result, no water was observed to migrate through the tape to the other side. As described above, the spot welding seal tape of the present invention is a pressure-sensitive conductive sheet made of rubber mixed with metal silicon alloy particles, or an adhesive having pressure-sensitive conductivity mixed with metal silicon alloy on one or both sides of the sheet. Since it is coated with , spot welding is possible and the welding strength is sufficiently satisfactory. Furthermore, this spot welding sealing material has a large apparent specific gravity, a large loss coefficient, and sufficient elasticity, so it has a great vibration damping effect on spot welded metal plates. In addition, the sealing material for spot welding of the present invention fully exhibits waterproof, rust-proof, and anti-corrosion effects, and the rubber tape does not become an obstacle during spot welding work, making it highly practical as it has good workability. It's big.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of an example of the welding seal material of the present invention, FIG. 2 is a schematic sectional view of another example of the welding seal material of the present invention, and FIG. 3 is a schematic sectional view of another example of the welding seal material of the present invention. For one example, pressurization (P
9 is a graph showing the relationship between one volume resistivity (pvQ and one touch). 1... Pressure-sensitive conductive adhesive layer, 2... Pressure-sensitive conductive sealing material, 3... Woven fabric or non-woven fabric support. Figure 1 Figure 2 Figure 3

Claims (1)

[Scope of Claims] 1. A sealing material for spot welding having vibration damping properties, comprising 2 to 70% of metal silicon alloy particles having a particle size of 15 μm to 2000 μm to a rubber-like elastic body. 2. A sealing material for spot welding having vibration damping properties as set forth in claim 1, which is obtained by applying or laminating the above-mentioned compound on both sides of a woven fabric, non-woven fabric, etc. 3. Claim 1 or 3, wherein a pressure-sensitive adhesive containing metal silicon alloy particles having a particle size of 15μ to 100μ in an amount of 1 to 10% based on the pressure-sensitive adhesive is coated on one or both sides of a sealing material. A sealing material for spot welding having vibration damping properties as described in item 2.