JP2519494B2 - Thermosetting high foam seal material - Google Patents

Description

TECHNICAL FIELD The present invention relates to a thermosetting high-foaming sealing material, and more particularly to a high-foaming sealing material that is treated on a steel plate at a temperature of 150 to 215 ° C. to foam. . The thermosetting high foam sealing material of the present invention is a spot sealing material mainly used in automobiles,
Fully filled in every corner of a complex panel, it exhibits excellent wind noise absorption and insulation.

[Prior Art] Thermosetting foam sealing materials used in automobiles and the like have been conventionally used for spot-weld seals, but the foaming rate of this type of sealing material is limited to around 100%.

Further, JP-A-62-62882 discloses a rubber-based foam composition (including rubber, a vulcanizing agent, a softening agent, a foaming material and an inorganic filler).
There is a disclosure of a highly foamable sealing material in which a composition in which the vulcanization temperature of a vulcanizing agent and the decomposition temperature of a foaming agent are in the same temperature region is kneaded, molded, and filled in a predetermined gap, and then heated and foamed. .

[Problems to be Solved by the Invention] In the conventional insertion work of the foam sealing material, since it is manually inserted through the work hole, the filling property varies, and the product is completely inserted along the shape in every corner. I can't. Further, since the work hole is the punched edge portion of the steel plate, there is a risk that the worker may hurt his hand.

Further, the composition known as a spot seal material has a foaming rate of 200% or less even if it has a high foaming rate, and a large amount of the composition is required for use in a place having a large filling volume, which causes a problem of increasing cost.

It is an object of the present invention to provide a composition for forming a sealing material having a high foaming rate, which is mainly filled in a cavity of a car body.

[Means for Solving Problems] The thermosetting high-foaming sealing material of the present invention comprises 100 parts of the entire composition.
In the case of parts by weight, rubber 25 to 40 parts by weight, vulcanizing agent 2 to 3 parts by weight, softener 25 to 40 parts by weight, foaming agent and foaming aid 1 to
A composition comprising 10 parts by weight and 15 to 30 parts by weight of an inorganic filler,
The inorganic filler constituting the composition is granular, and the softening agent has a viscosity at 100 ° C. of 30 cP or more, and a foaming agent / foaming aid ratio of 5/2 or less.

This composition includes various synthetic rubbers such as NR, SBR, IR, BR, CR and EPD depending on the purpose and application.
M etc. are used.

When the amount of this rubber is less than 25% by weight, the rubber elasticity is lowered and a high foaming rate cannot be obtained, and when it exceeds 40% by weight, it becomes too hard to achieve high foaming.

As the vulcanizing agent and the vulcanization accelerator, those normally used for rubber can be applied, but preferably a sulfur-based one such as sulfur,
A thiazole accelerator is used for the disulfide compound.

The vulcanizing agent and the vulcanization accelerator act on the elasticity of the rubber, and even if the addition amount is small or large, sufficient properties of the rubber cannot be exhibited.

The softening agent is used for the purpose of facilitating the processing of rubber,
It acts as a lubricant between rubber molecules, facilitates the relaxation phenomenon of polymer molecules, and improves processability, and mineral oils, vegetable oils, and the like are known. A highly viscous material is required to obtain the highly foamable sealing material of the present invention.
Since it is necessary that the viscosity at 0 ° C is 30 cP or more, it is preferable to use an aromatic oil. This softening agent becomes viscous at high temperatures, promotes film growth due to foaming, and enhances the retention of decomposed gas of the blowing agent to form a highly foamed product.

Inorganic fillers are mainly rubber fillers such as calcium carbonate, silica powder, barium sulphate, and ferrite, but the fluidity of rubber at high temperatures (that is, film formation)
A granular material having a small surface area that does not interfere with It does not damage the foamed film that is formed and imparts appropriate reinforcing properties, and its size is preferably a particle size of 1 to 10 μm. This granular material has an aspect ratio of 1
Is preferable. The foaming agent is a substance that decomposes when heated to generate carbon dioxide gas, nitrogen gas and the like. When the foaming agent is dispersed in rubber or the like, the decomposition will be slower than that of the foaming agent alone, and a large amount of undecomposed material will remain.Therefore, by using the auxiliary agent together, the decomposition is promoted, If possible, significantly lower the decomposition temperature. That is 150 to 215 ℃
It is preferable to generate a substantially uniform amount of gas at the temperature of, for example, azodicarbonamide, dinitrosobentamethylenetetramine and the like, and urea as a foaming aid.

The ratio of the foaming agent to the foaming auxiliary is required to be 5/2 or less in order to promote foaming, and preferably 5/5.

This composition is formed into a tape shape by extrusion molding or the like in an unvulcanized state. This tape is sticky to itself,
Since it is a flexible sheet that fits well with oil-faced steel sheets, it can be attached following various shapes. The steel plate to which this tape is attached is heated by an electro-deposition baking furnace to
When it is heated to 0 to 215 ° C, it foams to form a foam having a foaming rate of 600 to 1000%. Further, even when the foam is inside a panel having a complicated shape, the foam can be completely filled in every corner, and the cavity is filled to exhibit the effect of absorbing and insulating wind noise.

[Operation and Effect of the Invention] The thermosetting high-foam sealing material of the present invention comprises 25 to 40 parts by weight of rubber, 2 to 3 parts by weight of vulcanizing agent, 2 to 3 parts by weight of vulcanization accelerator, and 25 to 40 parts of softening agent. By weight, a foaming agent and a foaming aid 1 to 10 parts by weight, the composition of the inorganic filler 15 to 30 parts by weight, the inorganic filler constituting the composition is granular, the softening agent is 100 ℃.
Viscosity is 30 cP or more, and the ratio of foaming agent / foaming aid is 5 /
2 or less.

Since the sealing material of this composition is attached to the steel plate and heat-foamed in the process, the volume handled as the sealing material is small, and it has a large bulk like conventional rubber foam and urethane foam, and around the transportation and assembly process. When it is placed on the floor, it is easy to handle and does not take up space, unlike the space required. In addition, the unvulcanized tape-like material has adhesiveness to itself and is well compatible with oil-faced steel plates and can be attached to panels of various shapes in the painting process etc. be able to. It can also be applied to a closed space that could not be filled in the past.

[Examples] Hereinafter, the present invention will be described with reference to Examples and Comparative Examples.

In this composition, SBR was used as a rubber component, sulfur was used as a vulcanizing agent, thiuram type was used as a vulcanization accelerator, and the other components were mixed in the mixing ratios shown in Table 1. The unit is% by weight. The composition obtained by mixing was kneaded and then molded to form an unvulcanized rubber sheet. This rubber sheet was attached to a metal plate and heat-treated at 180 ° C. for 30 minutes in a heating furnace for electrodeposition coating to obtain a foam.

This rubber sheet has a thickness of 1.5 mm, and the foaming rate is expressed by a percentage by dividing the increase in thickness after foaming by the thickness before foaming.

(Evaluation) Nos. 1 to 4 of the examples are 100 ° C. within the composition range of the present invention.
Viscosity at 40cP, 60cP The high viscosity oil softener is used, the inorganic filler is granular calcium carbonate having a small surface area, and silica powder is used, and the ratio of the foaming agent and the foaming auxiliary agent is 5/2 or less.
The foaming rate of the obtained foam is 850 to 650%, which is 600% or more of the target value of the present invention.

In Example No. 1, the foaming ratio of the foam obtained when the softening agent of high viscosity II (60 cP), the inorganic filler is calcium carbonate, and the foaming agent / foaming aid = 5/5 is 850%.

Comparative Example No. 1 is a conventional foam composition having a low viscosity softening agent, which uses amorphous talc as an inorganic filler and has a small foaming ratio of 120%. Comparative example No.2 is comparative example page 1
Although the inorganic filler is made of granular calcium carbonate, the foaming rate is as small as 240%, which shows the importance of using a high-viscosity softening agent.

Example No. 2 is a case where the viscosity of the softening agent of Example No. 1 is lowered and high viscosity I (40 cP) is used, and in this case, the foaming rate is 620%.
It shows that the effect of the viscosity of the softening agent at high temperature is large.

Example No. 3 and Comparative Examples No. 3 and No. 4 are comparative examinations of inorganic fillers, and Example No. 3 uses granular silica powder and has a foaming rate of 750%. The comparative example No. 3 of the single-sided mica that does not have a foaming rate of 300% and the comparative example No. 4 of the amorphous talc had a small foaming rate of 260%, and the foam film formed by the shape of the inorganic filler was damaged. Therefore, it is considered that the growth of foam spheres is suppressed.

Example No. 4 and Comparative Example No. 5 are the results of comparative examination of the amount of the foaming aid, and the foaming agent / foaming aid ratio is 650% in the Example, but the ratio is 5/1 Comparative Example has a foaming ratio of 50
It becomes as small as 0%, indicating that it is necessary to accelerate the decomposition of the foaming agent by using a large amount of the foaming aid.

Therefore, the softening agent that constitutes the composition of the sealing material has a viscosity at 100 ° C of 30 cP or more, and the ratio of the foaming agent / foaming aid is 5 /
It is necessary that the inorganic filler has a columnar shape with a surface area of 2 or less and a small surface area so that the foaming rate is 600% or more.

Claims (3)

(57) [Claims] 1. Rubber 25 when the total composition is 100 parts by weight
-40 parts by weight, vulcanizing agent 2-3 parts by weight, vulcanization accelerator 2-3 parts by weight, softening agent 25-40 parts by weight, foaming agent and foaming auxiliary agent 1-
A composition comprising 10 parts by weight and 15 to 30 parts by weight of an inorganic filler, wherein the inorganic filler constituting the composition has a granular shape, and the softening agent has a viscosity at 100 ° C. of 30 cP (centipoise) or more. The thermosetting high foam sealing material, wherein the ratio of foaming agent / foaming aid is 5/2 or less. 2. The thermosetting high foam sealing material according to claim 1, wherein the foaming rate of the foam of the composition is 600% or more. 3. The thermosetting high foam sealing material according to claim 1, wherein the foaming agent is azodicarbonamide, dinitrosopentamethylenetetramine and the like, and the foaming aid is urea.