JP2001040310A - Spot-weldable adhesive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spot-weldable adhesive composition which reduces damage to the environment, excels in rust proof performance, and is capable of preventing contamination of an electrodeposition coating pretreating solution and the like, improving coating properties on the adhesive, reducing the odor in the interior of a vehicle due to weakening of the odor of a cured product and furthermore, reducing the amount to be coated by foaming and improving strain resistance due to the relaxation of cure shrinkage and the like by using an organic peroxide as the crosslinking agent for an uncrosslinked type and/or partially crosslinked type synthetic rubber without using a vinyl chloride resin together. SOLUTION: An adhesive composition contains, as the essential components, an uncrosslinked type and/or partially crosslinked type synthetic rubber, an organic peroxide, a blowing agent, a plasticizer, and a filler. It is preferred that 0.5-15 wt.% organic peroxide, 0.5-10 pts.wt. blowing agent, 100-600 pts.wt. filler, and 100-450 pts.wt. plasticizer are incorporated into 100 pts.wt. synthetic rubber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an automobile, an aircraft,
Possible to use spot welding and filling adhesion for steel plate joints in electrical equipment field, etc., and spot welding used for reinforcing adhesion between outer plate requiring high appearance and inner plate reinforcing it The present invention relates to an adhesive composition.

[0002]

[Related Art] For example, in an automobile manufacturing line, a paste-like adhesive mainly composed of an uncrosslinked and / or partially crosslinked synthetic rubber is applied to a joint of a body steel plate for waterproofing and rust prevention. It is hardened at the time of baking of electrodeposition coating as a combination and seal material (sealer).

[0003] For the crosslinking of uncrosslinked and / or partially crosslinked synthetic rubber, a method using sulfur is generally known. In the case of using this sulfur, the coating process is carried out before electrodeposition coating. Due to the treatment process, there is a problem of liquid contamination due to the adhesive compounding agent, a problem of paint contamination, and also a problem of odor in the completed vehicle interior due to a strong irritating odor of the cured product. Was.

As a means for solving these problems, crosslinking of an uncrosslinked and / or partially crosslinked synthetic rubber with a peroxide can be considered. However, as a countermeasure against this, a mastic adhesive or the like promotes surface hardening when used in combination with a PVC resin.

[0005] However, the adhesive composition used for the spot welded part is required to be stable against heat because a very high temperature is applied at the time of welding. Cannot be used if it generates corrosive gas (eg, chlorine gas) due to decomposition. Therefore, a vinyl chloride resin (which generates chlorine gas by decomposition) cannot be blended as an adhesive composition used for spot welding.

Accordingly, there is a need for a spot weldable adhesive composition which does not use sulfur as a cross-linking agent for the synthetic rubber and has good performance without blending a PVC resin. is there.

[0007]

SUMMARY OF THE INVENTION The present inventors have made intensive efforts to provide the above-mentioned novel adhesive composition, and as a result, have found that peroxide-crosslinked compounds of uncrosslinked or partially crosslinked synthetic rubber. By adding a foaming agent to the foam, the foaming agent decomposition gas generated during heat curing covers the adhesive surface, creating a barrier effect, preventing cross-linking inhibition by oxygen, and making the material excellent in surface curability. And completed the present invention.

The present invention uses an organic peroxide as a cross-linking agent for an uncross-linked and / or partially cross-linked synthetic rubber without using a vinyl chloride resin, thereby reducing harm to the environment and improving rust prevention performance. It is also excellent in prevention of contamination of the pretreatment solution for electrodeposition coating, etc., improvement of paintability on adhesive, reduction of odor in vehicle interior by alleviating odor of cured product, and application amount by foaming It is an object of the present invention to provide an adhesive composition which can be spot-welded and which can reduce distortion and improve strain resistance by relaxation of curing shrinkage.

[0009]

In order to solve the above-mentioned problems, the spot-weldable adhesive composition of the present invention comprises an uncrosslinked and / or partially crosslinked synthetic rubber, an organic peroxide,
It is characterized by containing a foaming agent, a plasticizer and a filler as essential components.

The mixing ratio of each component of the adhesive composition of the present invention is not particularly limited as long as the function and effect of the present invention can be achieved, but is 0.5 to 1 with respect to 100 parts by weight of the synthetic rubber.
5 parts by weight of organic peroxide, 0.5 to 10 parts by weight of blowing agent, 100 to 600 parts by weight of filler and 100 to 450 parts
Parts by weight of plasticizer can be used.

The uncrosslinked type synthetic rubber and the partially crosslinked type synthetic rubber of the present invention include a diene acrylonitrile-isoprene copolymer rubber (NIR) which can be crosslinked with a peroxide,
Acrylonitrile-butadiene copolymer rubber (NB
R), styrene-butadiene copolymer rubber (SBR),
Examples include isoprene rubber (IR) and butadiene rubber, and these can be used alone or in combination of two or more.

The uncrosslinked synthetic rubber and the partially crosslinked synthetic rubber can be used alone or in any proportion. The amount of the synthetic rubber used is 2 to 100 parts by weight of the total amount of the adhesive composition.
It is about 20 parts by weight, but preferably in the range of 5 to 15 parts by weight.

The organic peroxide of the present invention includes, for example,
Ketone peroxide, diacyl peroxide, alkyl peroxide, dialkyl peroxide, peroxyketal, alkyl perester, and the like can be used. The amount of the organic peroxide may be about 0.5 to 15 parts by weight, preferably 4 to 10 parts by weight, based on 100 parts by weight of the synthetic rubber.

The foaming agent of the present invention is not particularly limited as long as it generates nitrogen gas, carbon dioxide gas, carbon monoxide, carbon dioxide, ammonia gas and the like by heating.
A pyrolytic organic foaming agent is preferably used. For example, azo compounds (azodicarbonamide, azobisformamide, azobisisobutyronitrile, barium azodicarboxylate), nitroso compounds, hydrazine derivatives (4,
4'-oxybisbenzenesulfonyl hydrazide, sulfonyl hydrazide) and the like, and preferably,
It is an azo compound, more preferably azodicarbonamide.

As the foaming agent of the present invention, an inorganic foaming agent such as sodium bicarbonate may be used. These various foaming agents may be used alone or in combination of two or more. Further, if necessary, the above-mentioned foaming agent and a decomposition accelerator such as zinc white can be used in combination.

The foaming agent may be used in a proportion of 0.5 to 10 parts by weight, preferably 4 to 8 parts by weight, based on 100 parts by weight of the synthetic rubber. If the amount is less than 0.5 part by weight, the barrier effect is small and the surface curability is poor. In addition, 10
If the amount is more than the weight part, the physical property of the cured product is affected by the increase in the foaming rate.

Examples of the filler used in the present invention include calcium carbonate, talc, clay, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, mica, alumina, magnesium carbonate, silica powder, cellulose powder, and resin powder. And metal powder.

This filler is used in an amount of 100 to 600 parts by weight, preferably 300 parts by weight, based on 100 parts by weight of the synthetic rubber.
It is used in a proportion of up to 500 parts by weight.

As the plasticizer used in the present invention, for example, DOP, DBP, DIDP, DINP, BBP, D
HP, phosphate, adipic acid, ethylene glycol, higher alcohol phthalate, polyester-based plasticizer, epoxy-based plasticizer, and the like.
DIDP and DINP.

This plasticizer is used in an amount of 100 to 450 parts by weight, preferably 250 parts by weight, based on 100 parts by weight of the synthetic rubber.
It is used in a proportion of up to 350 parts by weight. These plasticizers can be used alone or in combination of two or more.

The adhesive composition of the present invention may further contain a known substance generally added to a synthetic rubber composition in order to impart necessary properties according to the purpose.

For example, an epoxy resin and its latent curing agent, a phenol resin, a polyamide resin, a silane coupling agent, a blocked amine, a blocked isocyanate, etc. are used as an adhesion-imparting agent in order to improve the adhesion to a rust-proof oil steel plate. And preferably, an antioxidant, a heat stabilizer, a lubricant, a release agent, a colorant, a flame retardant, an antistatic agent, a processing aid, and the like may be added.

[0023]

EXAMPLES The present invention will be described in more detail with reference to the following examples. However, it is needless to say that these examples are illustrative and should not be construed as limiting.

Example 1 First, 100 parts of synthetic rubber were used.
A part by weight of "JSRN230S" (uncrosslinked NBR manufactured by JSR Corporation) is masticated with a Banbury mixer, and 390 parts by weight of "NN-500" (calcium carbonate manufactured by Nitto Powder Co., Ltd.) is used as a filler. 370 parts by weight of "DINP" (manufactured by Mitsubishi Chemical Corporation) as a plasticizer is added and kneaded.

The kneaded batch prepared by the above procedure was transferred to a kneader, and 9 parts by weight of “Lupazole 231” (peroxyketals manufactured by Atochem Yoshitomi) as an organic peroxide and 5 parts by weight as a foaming agent "Uniform AZ"
(Azodicarbonamide manufactured by Otsuka Chemical Co., Ltd.) was sequentially mixed and uniformly dispersed.

Next, a performance evaluation test was performed on the obtained adhesive composition as follows.

First, the obtained adhesive composition was applied on a release paper to a thickness of 2 to 3 mm, and heated in an oven heated to 160 ° C. for 20 minutes to prepare a sheet-like cured product. After cooling the sheet to room temperature, the surface curability of the cured product was evaluated by observing the surface of the cured product. The results are shown in Table 1. The evaluation criteria for surface curability are as follows:
：: cured, ×: uncured.

Next, the obtained adhesive composition was applied to an SPC steel plate of 25 mm × 100 mm, and was applied to an SPC steel plate of 70 mm × 150 mm.
In addition to the above steel sheet, spot welding was performed, a combined cycle corrosion test was performed, and the presence or absence of rust around the spot weld was confirmed. The results are shown in Table 1. The evaluation criteria for rust prevention during welding were indicated by ○: no rusting, ×: rusting.

The obtained adhesive composition (3 to 5 g) was coated on an aluminum plate of a known mass in the form of a semicircular bead having a diameter of about 10 mm and a length of 50 mm, and then placed in an oven heated to 160 ° C. for 20 minutes. After heating, the volume change rate was calculated by the water displacement method, and the results are shown in Table 1.

Further, the obtained adhesive composition (70 to 1)
00g) was mixed in 1 liter of the pretreatment for electrodeposition coating (ED), and the change in the concentration of the pretreatment for electrodeposition coating after leaving at 40 ° C. for 3 hours was measured. The results are shown in Table 1. Evaluation criteria for ED pretreatment liquid contamination were as follows: ：: Concentration change rate within 10%,
X: when the rate of change in density exceeds 10%,

3 kg of the obtained adhesive composition (3 to 5 g)
It was placed in a can, heated in an oven heated to 160 ° C. for 20 minutes, cooled to room temperature, and evaluated for odor. The results are shown in Table 1. The evaluation criteria of the odor were indicated by ○: slight odor, ×: unpleasant odor.

The obtained adhesive composition was coated on a steel plate with a diameter of 10
mm, 100 mm long semi-circular bead,
Heat in an oven heated to 20 ° C for 20 minutes, and after cooling,
An automotive paint was applied and heated in an oven heated to 140 ° C. for 20 minutes to evaluate the paintability.
It was shown to. The evaluation criteria for paintability were as follows: な し: no discoloration of paint,
X: Discoloration of the paint was observed.

(Examples 2 to 6) Each adhesive composition was prepared in the same procedure as in Example 1 according to the composition shown in Table 1. The performance of each of the obtained adhesive compositions was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

(Comparative Examples 1 to 4) Each adhesive composition was prepared in the same procedure as in Example 1 according to the formulation shown in Table 1. The performance of each of the obtained adhesive compositions was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[0035]

[Table 1]

The annotations in Table 1 are as follows. 1) NBR “JSRN230S” manufactured by JSR Corporation 2) SBR “Nipol 1009” manufactured by Zeon Corporation 3) Calcium carbonate “NN-500” manufactured by Nitto Powder Chemical Co., Ltd. 4) Plasticizer manufactured by Mitsubishi Chemical Corporation "DINP" 5) Organic peroxide "Lupazole 2" manufactured by Atochem Yoshitomi Co., Ltd.
31) 6) Organic peroxide "t-butyl perbenzoate" manufactured by Atochem Yoshitomi Co., Ltd. 7) Azo-based blowing agent "Uniform AZ" manufactured by Otsuka Chemical Co., Ltd. 8) Hydrazine-based blowing agent manufactured by Eiwa Chemical Industry Co., Ltd. "Neocervone N1000" 9) Matsumoto Yushi Co., Ltd. unfoamed resin balloon "Matsumoto Miculsfar F-82D" 10) Dow Chemical Japan Co., Ltd. epoxy resin "D.
E. FIG. R. 331 ”11) PVC resin“ Kanevinyl PCH-183 ”manufactured by Kanekabuchi Chemical Industry Co., Ltd.

As is clear from the results of the performance evaluations shown in Table 1, the adhesive compositions of the present invention (Examples 1 to 6) had surface curability, rust preventive performance during welding, and contamination of the ED pretreatment liquid. sex,
The cured product has good odor and good paintability, and the volume change rate is positive (13% to 36%). It can be expected that cost reduction can be expected by reducing the amount of use due to volume expansion, and the gap filling effect can be expected. Excellent results were shown.

On the other hand, in Comparative Example 1 (in which the foaming agent was removed from the adhesive composition of the present invention), the surface curability was poor, the rate of change in volume was negative, and the cost increased due to the volume shrinkage. Turns out to be disadvantageous.

In Comparative Example 2 (in which the foaming agent was removed from the adhesive composition of the present invention and unfoamed balloons were added), the volume change rate was positive, but the surface curability was poor.

Comparative Example 3 (in which the foaming agent was removed from the adhesive composition of the present invention and a PVC resin was added) had good surface curability, but poor rust prevention performance during welding and a negative rate of change in volume. Was found to be disadvantageous.

In Comparative Example 4 (in which the organic peroxide and the foaming agent were removed from the adhesive composition of the present invention and sulfur was used as a cross-linking agent), although the surface curability and the rust prevention performance during welding were good, It was found that there was a disadvantage that the ED pretreatment liquid contamination, the odor of the cured product, and the coating property were poor and the volume change rate was negative.

[0042]

As described above, the adhesive composition which can be spot-welded according to the present invention comprises an organic peroxide as a crosslinking agent for an uncrosslinked and / or partially crosslinked synthetic rubber without using a PVC resin. By using it, it is less harmful to the environment and has excellent rust prevention performance, and also prevents contamination of pretreatment liquid for electrodeposition coating, improves paintability on adhesive, and reduces odor of cured product. There is a great effect that the odor in the vehicle interior can be reduced, and further, the application amount can be reduced by foaming, and the distortion resistance can be improved by alleviating curing shrinkage.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J040 CA051 CA061 CA071 CA081 CA091 CA101 HA136 HA156 HA196 HA296 HA356 HB10 HB34 HB41 HC14 HC15 HC17 HD23 KA31 KA37 KA42 LA08 LA11 MA02 NA15

Claims (2)

[Claims] 1. An adhesive composition capable of spot welding comprising an uncrosslinked and / or partially crosslinked synthetic rubber, an organic peroxide, a foaming agent, a plasticizer and a filler as essential components. . 2. With respect to 100 parts by weight of the synthetic rubber,
0.5 to 15 parts by weight of organic peroxide, 0.5 to 10 parts by weight of blowing agent, 100 to 600 parts by weight of filler and 100
2. The adhesive composition according to claim 1, wherein a plasticizer is blended in an amount of up to 450 parts by weight.