JP5707077B2 - Mastic adhesive - Google Patents

Description

  The present invention relates to an mastic adhesive that functions as an adhesive and a cushioning material between an outer panel and an inner panel such as an automobile bonnet, trunk lid, door, and roof for the purpose of vibration isolation of the panel.

Conventionally, mastic adhesives are mainly composed of materials such as heat-curable synthetic rubber or thermoplastic resin, and join members such as outer panels and inner panels and other panels that make up the automobile body. Therefore, it is used in an automobile production line (for example, see Patent Document 1).
A foaming agent is added to this mastic adhesive in order to fill a gap and reduce strain. However, when the adhesive itself is foamed by heating, sufficient strength may not be ensured.
As a countermeasure, a method in which a foaming agent is not added is conceivable. However, since shrinkage cannot be relaxed during heat curing, the adhesive-attached surface is drawn and distortion occurs.
As another countermeasure, there is a method of ensuring strength by adding a large amount of a crosslinking agent to a composition in which a normal amount of a foaming agent is added, but the embrittlement after heat curing becomes large and the toughness is lost, and vibration and There is a possibility that the adhesive peels off or breaks along with the deformation of the vehicle body.

JP 2007-291247 A

  Accordingly, an object of the present invention is to provide a mastic adhesive which is not easily distorted even when heat-cured and has excellent strength.

In order to solve the above-mentioned problems, the present inventors have intensively studied, and by incorporating at least two types of resin hollow bodies having different average particle diameters into a mastic adhesive mainly composed of rubber, the above problems can be solved. As a result of finding out that it can be solved, the present inventors have found a solution as follows.
That is, the mastic adhesive of the present invention is a mastic adhesive that cures by a crosslinking reaction using rubber as a main component as described in claim 1, and the mastic adhesive has a mean particle size of 20 μm as a resin hollow body. The first resin hollow body of ˜40 μm is added to 6 parts by mass to 12 parts by mass with respect to 100 parts by mass of the rubber , and the second resin hollow body having an average particle diameter of 50 μm to 70 μm is added to 100 parts by mass of the rubber. On the other hand, it contains 4 to 9 parts by mass.
The present invention according to claim 2 is characterized in that, in the invention according to claim 1, the resin hollow body is composed of any one of acrylonitrile, MMA, vinylidene chloride and methacrylonitrile.

  According to the present mastic adhesive, it is possible to obtain high strength after heat-curing and reduce body distortion.

The rubber as the main component of the mastic adhesive of the present invention is not particularly limited as long as it is a rubber, regardless of whether it is a crosslinked type or an uncrosslinked type, but can be used alone or in combination. The partially crosslinked synthetic rubber includes acrylonitrile-isoprene copolymer rubber (NIR), acrylonitrile-butadiene copolymer rubber (NBR), styrene-butadiene copolymer rubber (SBR), butadiene rubber (BR), and isoprene rubber. In addition, a diene rubber such as a rubber obtained by mixing at least two of these rubbers, which is partially heated and cross-linked in advance using a cross-linking agent such as divinylbenzene or sulfur, can be used. In addition, as the uncrosslinked type synthetic rubber, for example, those similar to the partially crosslinked type synthetic rubber described above can be used.
Among the above, for reasons of processability and cost, it is preferable to use one containing either or both of butadiene rubber and styrene-butadiene rubber.

  The constituent material of the resin hollow body is not particularly limited as long as it is a resin, but examples thereof include acrylonitrile, MMA, vinylidene chloride, methacrylonitrile and the like. In addition, when using a glass hollow body, as will be described later, when the mastic adhesive is in a deformed state with a small amount of deformation, the effect of relaxing the distortion is inferior. There is a problem that pump wear tends to occur.

In order to cure the rubber by a crosslinking reaction, a crosslinking agent and a crosslinking accelerator are added.
Examples of the crosslinking agent include sulfur, dibenzothiazyl disulfide, thiuram polysulfide compounds such as tetramethylthiuram disulfide and dipentamethylenethiuram tetrasulfide, 4,4-dithiomorpholine, p-quinonedioxime, p, p'- Dibenzoquinone dioxime, cyclic sulfur imide, and peroxide can be used. The amount of the vulcanizing agent is 3 to 20 parts by mass with respect to 100 parts by mass of rubber. If it is less than 3 parts by mass, the rubber in the composition will not be sufficiently vulcanized, and it will be difficult to recover after the mastic adhesive is deformed due to the movement or vibration of the panel. There is a risk that. When the amount exceeds 20 parts by mass, the rubber elasticity after heat curing of the composition is lost, and there is a risk of cracking due to movement or vibration of the panel. Moreover, since it is too hard, there exists a possibility of producing a distortion.

  Examples of the crosslinking accelerator include thiuram-based, substituted dithiocarbamate-based, guanidine-based, thiazole-based, sulfenamide-based, thiourea-based, xanthate-based, and the like. At least one selected from these is blended. be able to. The blending amount of this vulcanization accelerator is 3 to 20 parts by mass with respect to 100 parts by mass of rubber. If the amount is less than 3 parts by mass, the rubber in the composition is not sufficiently vulcanized and is difficult to recover after being deformed by the movement or vibration of the panel, etc. is there. If it exceeds 20 parts by mass, the rubber elasticity after heat curing of the composition is lost, and there is a risk of cracking due to movement or vibration of the panel. Moreover, it is because there exists a possibility of producing a distortion because it is too hard.

In this invention, 10-20 mass parts of resin-made hollow bodies are contained with respect to 100 mass parts of rubber | gum . This is because if the amount is less than 10 parts by weight, distortion tends to occur, and if it exceeds 20 parts by weight, the strength is poor.
The resin hollow body has at least two different average particle diameters, that is, a first resin hollow body having an average particle diameter of 20 to 40 μm, and a second resin hollow body having an average particle diameter of 50 to 70 μm; Consists of. The second resin hollow body having a large average particle diameter relaxes the shrinkage when the rubber component is cross-linked by deformation, suppresses the stress that pulls the adherend surface, and the first resin hollow body has a small average particle diameter. The body secures strength against a large deformation that is greater than or equal to the object of the second resin hollow body.
The mastic adhesive of the present invention preferably has a volume change after heat curing of 10% or less in order to ensure strength. Note that the first resin hollow body having a small average particle size contributes to securing the strength. This is because the volume change rate can be kept low, and the material for crosslinking the rubber can be reduced.

  Moreover, you may make it add the material added conventionally, for example, a filler, a softening agent, a moisture absorption inhibitor, a foaming agent, etc. to the mastic adhesive of this invention.

  Specific examples of the filler include, for example, wood powder, pulp, cotton chips, asbestos, glass fiber, carbon fiber, mica, walnut shell powder, rice husk powder, graphite, diatomaceous earth, white clay, fume silica, precipitated silica, Examples thereof include anhydrous silicic acid, carbon black, calcium carbonate, clay, talc, titanium oxide, magnesium carbonate, quartz, aluminum fine powder, flint powder, and zinc dust. These may be subjected to surface treatment for the purpose of preventing secondary aggregation of the small particle size filler. Among these fillers, it is preferable to use calcium carbonate. The blending amount of the filler is 50 to 500 parts by mass with respect to 100 parts by mass of rubber. If it is less than 50 parts by mass, the thixotropy of the composition is lowered, and the adhesive drips after application, which is not preferable. On the other hand, when the amount exceeds 500 parts by mass, it is necessary to add a large amount of liquid components such as a plasticizer, a softening agent, and a solvent in order to make the composition have a viscosity that can be applied. Adhesion with the panel which is a site | part will worsen, and there exists a possibility that an adhesive may peel off by a motion, vibration, etc. of a panel.

  Examples of the softening agent include phthalic acid esters and petroleum-distilled products such as DOP, DBP, DIDP, BBP, DINP, DHP, sulfonic acid, phosphoric acid, and higher alcohol phthalate. The amount of the plasticizer is 50 to 500 parts by mass with respect to 100 parts by mass of rubber. If it is less than 50 parts by weight, the viscosity of the composition is too high to be applied, and even if it can be applied, the composition after heat-curing tends to become brittle and breaks due to vibration and movement of the panel. There is a risk that. If it exceeds 500 parts by mass, it may sag after application.

  As the foaming agent, azodicarbonamide (ADCA) or azodicarbonamide (ADCA) coated with a water repellent treatment can be used. As a specific product name, Cellmic CAP500 (Sankyo) Kasei Co., Ltd.) and Vinyl Hall ST # 70 (manufactured by Eiwa Kasei Kogyo Co., Ltd.). Moreover, oxybisbenzene sulfonyl hydrazide (OBSH), DPT, etc. can be used as a foaming agent in which the process is not performed.

  Examples 1 to 4 and Comparative Examples 1 to 9 were prepared by blending the following blending materials with the composition shown in Table 1.

[Combined raw materials]
(1) Synthetic rubber: Styrene-butadiene copolymer rubber (manufactured by JSR Corporation, model number: SL552), butadiene rubber (BR) (manufactured by Ube Industries, Ltd. model number: BR113P)
(2) Filler / surface treated calcium carbonate (Takehara Chemical Industry Co., Ltd. Model: Neolite AT1)
・ Calcium carbonate (manufactured by Sankyo Flour Milling Co., Ltd. Model: Heavy Calcium Carbonate Special # 1)
(3) Softener: “DINP” (manufactured by J-Plus Co., Ltd., model number: DINP), “process oil” (manufactured by Sankyo Oil Chemical Co., Ltd., model number: SNH-22)
(4) Hygroscopic inhibitor: Calcium oxide (Omi Chemical Co., Ltd. Model number: CML-35)
(5) Foaming agent: Azodicarbonamide (manufactured by Sankyo Kasei Co., Ltd. Model number: Cellmic CAP500)
(6) Crosslinking agent: sulfur (manufactured by Hosoi Chemical Co., Ltd., model number: powdered sulfur)
(7) Cross-linking accelerator: p-quinone dioxime (manufactured by Ouchi Shinsei Chemical Industry Co., Ltd., model number: Barnock GM), dibenzothiazyl disulfide (manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. model number: Noxeller DM)
(8) Resin hollow body:
-Average particle size of 20-40 μm: (Matsumoto Yushi Co., Ltd. model number: 100 SCA)
-Average particle diameter 50-70 micrometers: (Matsumoto Yushi Co., Ltd. model number: 100MCA)

Using the examples and comparative examples, an evaluation test was conducted under the following conditions, and the results are shown in Table 1 (FIG. 1).
(1) 10% displacement tensile strength:
Apply the composition of each example to a 1.6 mm thick x 25 mm x 100 mm SPC steel plate and cross the SPC steel plate of the same size in a cross so that it becomes a 3 mm thick x 25 mm x 15 mm shape using a 3 mm spacer. Hold it in place and fix it with clips. The test piece is heated at 170 ° C. for 20 minutes to cure the composition of each example. The test piece after curing is cured for 24 hours in a thermostatic chamber at 23 ° C. ± 2 ° C., and the test is carried out at the room temperature after removing the spacers and clips. The tester uses an autograph or the like capable of a tensile test. The sandwiched SPC steel plate is set on an autograph gripping jig and pulled at a pulling speed of 5 mm / min. Record the load (N) at 10% displacement (0.3mm displacement) with respect to the thickness of 3 mm, and divide by the cross-sectional area (15 mm × 25 mm) of the composition as 10% displacement tensile strength. To do. In addition, evaluation of Table 1 made 25 kPa or less (circle), and other than made x.
(2) 50% displacement tensile strength:
A test piece is prepared under the same conditions as in (1) above, and the test is performed under the same testing machine and conditions. Record the load (N) at 50% displacement (1.5mm displacement) with respect to the thickness of 3mm, and divide by the sectional area of the composition (15mm x 25mm) (kPa) as the 50% displacement tensile strength. To do. In addition, the evaluation in Table 1 made 100 kPa or more (circle) and other than x.
(3) 50% compressive strength:
Apply the composition of each example to a 1.6mm thick × 25mm × 100mm SPC steel plate and sandwich the SPC steel plate of the same size into a 5mm thick × 25mm × 25mm shape using a 5mm spacer, etc. Secure with. The test piece is heated at 170 ° C. for 20 minutes to cure the composition of each example. The test piece after curing is cured for 24 hours in a thermostatic chamber at 23 ° C. ± 2 ° C., and the test is carried out at the room temperature after removing the spacers and clips. The tester uses an autograph or the like capable of testing in the compression direction. The test piece is set on a compression jig and is carried out at a compression speed of 50 mm / min. The load (N) at the time of 50% compression displacement (at 2.5 mm compression displacement) with respect to the thickness of 5 mm is defined as 50% compression load. In addition, the evaluation in Table 1 made 500N or more (circle) and other than x.
(4) Steel sheet retractability:
0.8 mm thick x 25 mm x 100 mm SPC so that the composition of each example is applied to a 1.6 mm thick x 25 mm x 100 mm SPC steel plate and a 5 mm spacer is used to form a shape of 5 mm thick x 25 mm x 25 mm Insert the steel plate from above and fix it to the spacer with a clip. The specimen is allowed to stand for 6 hours or more in a constant temperature room at 23 ° C. ± 2 ° C., and then the thickness (T0) including the sandwiched SPC steel plate and the sample is measured with a dial gauge or the like. Thereafter, the composition is heated at 170 ° C. for 20 minutes to cure the composition of each example. After curing, the specimens were cured in a thermostatic chamber at 23 ° C ± 2 ° C for 3 hours or longer, then the spacers and clips were removed, and the samples were allowed to stand for 10 minutes or more at the same temperature, and then sandwiched between the SPC steel plate and the sample. The thickness (T1) including is measured with a dial gauge or the like. The value (mm) obtained by subtracting the thickness (T1) after curing from the thickness (T0) before curing was defined as steel sheet retractability, and the evaluations in Table 1 were evaluated as “O” within ± 0.2 mm and “X”.

Since the comparative example 1 comprised from the resin-made hollow body of one kind of average particle diameter from Table 1 comprised from the thing with an average particle diameter of 20-40 micrometers, there exists a problem in the tensile strength of 10% displacement, and a steel plate retractability. I understood that. Similarly, Comparative Example 2 composed of a single resin hollow body having an average particle diameter is composed only of those having an average particle diameter of 50 to 70 μm. I found out that
Moreover, since the content of the resin-made hollow bodies was outside the scope of the present invention in Comparative Examples 3 to 5, it was found that there were problems with any of the evaluation items.
It turned out that the comparative example 6 comprised from the resin-made hollow body of 10-20 micrometers whose average particle diameter is still smaller than the comparative example 1 has a problem in the tensile strength of 10% displacement, and a steel plate drawability.
It turned out that the comparative example 7 comprised from the resin-made hollow body of 80-110 micrometers whose average particle diameter is still larger than the comparative example 2 has a problem in the tensile strength of 50% displacement, and 50% compressive strength.
Since Comparative Examples 7 and 8 have either a small particle size or a large particle size out of the scope of the present invention, there are problems with any of the evaluation items. I understood.
It turned out that Examples 1-4 are excellent in all the evaluation items with respect to these comparative examples.

  The mastic adhesive of the present invention can be widely used industrially including structures such as automobiles.

Claims (2)

A mastic adhesive that cures by a crosslinking reaction with rubber as a main component,
The mastic adhesive is a resin hollow body, and the first resin hollow body having an average particle diameter of 20 μm to 40 μm is 6 parts by mass to 12 parts by mass with respect to 100 parts by mass of the rubber , and the average particle diameter is 50 μm to The mastic adhesive characterized by containing 4-9 mass parts of 70 micrometers 2nd resin-made hollow bodies with respect to 100 mass parts of said rubber | gum .   The mastic adhesive according to claim 1, wherein the hollow resin body is made of any one of acrylonitrile, MMA, vinylidene chloride, and methacrylonitrile.