JP2001254071A - Vulcanizable, highly expandable sealing material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vulcanizable, highly expandable sealing material which shows reduced deterioration of expansion performance on storage and is attached to the inner side of a hollow body at an unexpanded state and then vulcanized and expanded through heating to fill inside the hollow body. SOLUTION: The vulcanizable, highly expandable sealing material comprises a blended product containing a rubbery polymer, a sulfur vulcanizing agent, a vulcanization accelerator and a foaming agent as components, wherein the vulcanization accelerator contains at least iron dimethyldithiocarbamate and/or copper dimethyldithiocarbamate and tiurams. The sealing material has an initial expansion ratio measured under a specific condition of >=6 and an expansion ratio measured after 7 days of storage at 60 deg.C of >=60% of the initial expansion ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vulcanized high-foaming sealing material which is adhered to the inside of a hollow body in an unfoamed state, vulcanized and foamed by heating to fill the inside of the hollow body.

[0002]

2. Description of the Related Art Conventionally, a hollow portion such as the interior of a pillar of an automobile is filled with a rubber-based foam to satisfy requirements such as heat insulation, vibration proof, sound proof and mechanical strength. In this method, a foam sealing material in which a vulcanizing agent, a vulcanization accelerator, a foaming agent and a foaming aid are mixed with a rubber-based polymer is attached to the inside of the pillar, and the foamed material is heated and foamed at a location where heat is applied, such as an electrodeposition coating line. Then, the inside of the pillar is filled.

[0003] However, since the rubber foam is stored in a warehouse or the like after it is manufactured, it is stored in a warehouse or the like until it is actually used. In some cases, the vulcanization proceeds, and the foaming performance of the sealing material is reduced.

[0004] Therefore, even when the foam is heated and foamed inside the pillar, predetermined foaming is not performed due to a decrease in the foaming performance of the sealing material, and there is a problem that the inside of the pillar cannot be completely filled.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has as its object to develop a vulcanization-type high-foaming sealing material in which the foaming performance is hardly reduced by storage. .

[0006]

SUMMARY OF THE INVENTION The present invention relates to a vulcanized high-foaming sealing material which is adhered to a hollow body in an unfoamed state, vulcanized and foamed by heating to fill the hollow body, It is a mixture containing at least a rubber-based polymer, a sulfur-based vulcanizing agent, a vulcanization accelerator and a foaming agent, wherein the vulcanization accelerator contains at least iron dimethyldithiocarbamate and / or copper dimethyldithiocarbamate and thiurams. The initial foam height ratio measured under the following conditions is 6
The present invention provides a vulcanized high-foamable sealing material characterized in that the foaming height after storage at 60 ° C. for 7 days is 50% or more of the initial level (claim 1). (1) Specimen height 4 mm × width 30 mm × length 80 mm (2) Foaming conditions Put into a 160 ° C thermostat for 15 minutes

Particularly preferably, the thiurams are mixed in a ratio (weight ratio) of 0.5 to 20 with respect to a total amount of the iron dimethyldithiocarbamate and / or copper dimethyldithiocarbamate of 1 (claim 2). Wherein the sulfur-based vulcanizing agent is sulfur (Claim 3) and the rubber-based polymer is styrene-butadiene rubber, styrene-butadiene-styrene elastomer or butadiene elastomer (Claim 4). Provide a foam sealing material.

[0008]

According to the present invention, by using iron dimethyldithiocarbamate and / or copper dimethyldithiocarbamate together with thiurams as a vulcanization accelerator, vulcanization / foaming treatment with a high expansion ratio can be achieved, Since the progress of vulcanization is small, it is possible to prevent a decrease in foaming performance. Therefore, the vulcanization-type high-foaming sealing material of the present invention can efficiently fill the inside of a hollow portion and impart heat insulating properties, vibration proof properties, sound proof properties, mechanical strength, and the like. Furthermore, even if stored for a long time in a warehouse or the like until it is actually used after production, especially when it is left in an environment where temperature is added, such as in the summer, its foaming performance does not decrease much and maintains good foaming performance. It is.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A vulcanization type highly foamed sealing material according to the present invention comprises a vulcanized foam of an admixture containing at least a rubber-based polymer, a sulfur-based vulcanizing agent, a vulcanization accelerator and a foaming agent. .

The rubber-based polymer used in the present invention includes:
Rubber or a thermoplastic elastomer that can be vulcanized with sulfur can be used as appropriate, for example, butadiene rubber, styrene-butadiene rubber, styrene-butadiene-styrene rubber, isoprene rubber, chloroprene rubber, acrylonitrile-butadiene rubber, butyl rubber, styrene-
Isoprene-styrene rubber, styrene-ethylene-butadiene rubber, styrene-ethylene-butylene-styrene rubber, ethylene-propylene-diene rubber, styrene-
Isoprene-propylene-styrene rubber, natural rubber, and a rubber-based polymer composed of these partially hydrogenated,
Styrene-butadiene-styrene elastomer, styrene-isoprene-styrene elastomer, butadiene elastomer and the like can be mentioned, and these can be used alone or in combination of two or more.

Particularly, in the present invention, styrene-butadiene rubber, styrene-butadiene-styrene elastomer, and butadiene elastomer are preferable from the viewpoint of processability, foamability, and the like.

In the present invention, a sulfur-based vulcanizing agent such as sulfur, sulfur chloride, sulfur monochloride, sulfur dichloride or the like is used as the vulcanizing agent. It is preferable to use sulfur from the viewpoint of tackiness and the like.
The amount of sulfur used can be appropriately determined according to the type of the rubber-based polymer to be used, the physical properties of the foam to be used, and the like, and is usually 0.1 to 1 per 100 parts by weight of the rubber-based polymer.
0 parts by weight, preferably 0.5 to 5 parts by weight.

The present invention is characterized in that iron dimethyldithiocarbamate and / or copper dimethyldithiocarbamate and thiurams are used in combination as vulcanization accelerators. By using these in combination, it is possible to achieve a vulcanization-type high-foaming sealing material in which vulcanization / foaming treatment with a high expansion ratio can be achieved and the foaming performance is not reduced by storage.

The thiurams used herein include tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide,
Tetramethylthiuram monosulfide, N, N'-dimethyl-N, N'-diphenylthiuram disulfide, dipentamethylenethiuram disulfide, dipentamethylenethiuram pentasulfide, mixed alkylthiuram disulfide, and the like can be mentioned alone. Alternatively, two or more kinds can be used as a mixture.

Particularly, in the present invention, it is preferable to use tetramethylthiuram monosulfide from the viewpoint of maintaining foaming performance.

In addition to the above two types of vulcanization accelerators,
Other vulcanization accelerators can be used in combination as long as the effects of the present invention are not impaired. Examples of the vulcanization accelerator that can be used in combination include guanidines, thiazoles, sulfenamides, dithiocarbamic acids, xanthogens, aldehyde ammonias, aldehyde amines, and thioureas.

These vulcanization accelerators are rubber-based polymers 1
It is appropriate to use 0.1 to 10 parts by weight, preferably about 1 to 8 parts by weight, based on 00 parts by weight, but it is not limited thereto.

The mixing ratio (weight ratio) of iron dimethyldithiocarbamate and / or copper dimethyldithiocarbamate to thiurams can be arbitrarily set according to the physical properties of the desired foam. The thiurams are 0.5 to 20, preferably 1 to 10, more preferably 2 to 5, based on the total amount of iron acid and / or copper dimethyldithiocarbamate of 1. If the compounding ratio of the thiurams is less than 0.5, the initial expansion height ratio tends to be small, and if it exceeds 20, the reduction in the expansion height ratio after storage tends to increase, and neither is preferable.

In the present invention, any suitable foaming agent can be used. For example, fluorinated alkanes such as trichloromonofluoromethane and dichloromonofluoromethane, azobisisobutyronitrile and azodicarboxylic amide (ADCA) can be used. ), Azo compounds such as barium azodicarboxylate, hydrazines such as paratoluenesulfonylhydrazide, diphenylsulfone-3,3'-disulfonylhydrazide, 4,4'-oxybis (benzenesulfonylhydrazide), and allylbis (sulfonylhydrazide) Semi-carbazide compounds such as p-toluylenesulfonyl semicarbazide and 4,4'-oxybis (benzenesulfonyl semicarbazide);
Triazole compounds such as 5-morpholyl-1,2,3,4-thiatriazole, N, N'-dinitrosopentamethylenetetramine and N, N'-dimethyl-N, N '
Organic blowing agents such as N-nitroso compounds such as -dinitrosoterephthalamide, and inorganic blowing agents such as ammonium carbonate, sodium bicarbonate and anhydrous sodium nitrate. These may be used alone or in combination of two or more. It can be mixed and used.

In the present invention, among these foaming agents, azodicarboxylic acid amide (ADCA) is preferably used in view of safety due to self-digestion and non-toxicity.

The amount of the foaming agent to be used can be appropriately determined according to the kind of the foaming agent to be used, the physical properties of the desired foam by the expansion ratio, and the like. For example, azodicarboxylic acid amide (A
DCA), 1 per 100 parts by weight of the rubber-based polymer
５０50 parts by weight, preferably 10-40 parts by weight.

Also, azodicarboxylic acid amide (ADCA)
A foaming aid can be used for the purpose of lowering the decomposition temperature. Examples of the foaming auxiliary used in the present invention include urea-based, salicylic acid-based, and benzoic acid-based foaming aids. It is preferable to use a urea-based foaming aid from the viewpoint of foaming efficiency. The amount used is adjusted as a compounding ratio with the foaming agent to be used.
It is about 4: 1 to 1: 1 (weight ratio).

The vulcanized foam of the present invention comprises a rubber-based polymer, a sulfur-based vulcanizing agent, a vulcanization accelerator and an admixture containing at least a foaming agent. In addition, substances other than the above essential components may be added.

For example, the admixture may be used as a softening agent for the purpose of adjusting the moldability, for example, paraffins such as chlorinated paraffin, waxes, naphthenes, aromas, and the like.
Drying oils such as asphalt and linseed oil, animal and vegetable oils, petroleum oils, various low molecular weight polymers, phthalates, phosphates, stearic acid and its esters, alkyl sulfonates, adhesive An imparting agent or the like can be added. In addition, stearic acid and its esters are also useful as a lubricant, and therefore, are examples of components that can also contain various lubricants.

Further, the above-mentioned admixture includes talc, calcium carbonate, magnesium carbonate, silicic acid and salts thereof, clay, mica powder, aluminum hydroxide, magnesium hydroxide, zinc white, bentonine, carbon black, silica, alumina, Fillers such as aluminum silicate, acetylene black, and aluminum powder, and other appropriate additives such as plasticizers, antioxidants, antioxidants, pigments, colorants, and fungicides can be added as necessary. . The above-mentioned calcium carbonate is also useful as a moisture absorbent, zinc white is useful as a stabilizer, and carbon black is also useful as a reinforcing agent. Therefore, examples of the components that can also contain various stabilizers and reinforcing agents are given.

For the purpose of adjusting physical properties such as the strength of the obtained foam, one or more non-rubber polymers can be blended. Examples of these non-rubber polymers include acrylic polymers such as poly (meth) acrylates, polyvinyl chloride, polyethylene, ethylene-vinyl acetate copolymer, polyvinyl acetate, and the like.
Polyamide, polyester, chlorinated polyethylene, urethane-based polymer, styrene-based polymer, silicone-based polymer, epoxy-based resin and the like can be blended.
The amount to be used is 50% by weight or less, preferably 30% by weight of the rubber-based polymer in order to maintain the rubbery properties of the foam.
% By weight, especially 15% by weight or less.

The vulcanized high-foaming sealing material of the present invention comprises:
Mix the above mixture and other ingredients as needed,
It can be kneaded by a conventionally known method such as a kneader and formed into a predetermined form by an appropriate method such as a mixing roll, a calender roll, or extrusion molding. At this time, although it depends on the composition, it is preferable to process at 60 ° C. or lower in order to suppress the progress of vulcanization and curing and the decomposition of the foaming agent.

The vulcanized high-foaming sealing material of the present invention is, for example, adhered to a hollow portion such as the inside of a pillar of an automobile, and then vulcanized and foamed by heating in any manner to provide heat insulation, sound insulation, and vibration isolation. Forming a sealing material with excellent properties. At this time, the conditions of the vulcanization and foaming treatment can be appropriately determined according to the properties of the vulcanizing agent and the foaming agent used, but are generally 200 ° C. or lower, preferably 1 ° C. or lower.
It is about 40 ° C to 180 ° C.

In the present invention, the foaming ratio of the foam to be formed must be 6 times or more in the initial foam height ratio measured under the following conditions. (1) Specimen height 4 mm x width 30 mm x length 80 mm (2) Foaming condition Put into a 160 ° C constant temperature bath for 15 minutes

Here, the foaming height magnification means a magnification of a maximum value of a height after foaming with respect to a height (4 mm) before foaming when a plate-like test piece of the above size is foamed. The term “initial” refers to a measured value within 3 days of storage at room temperature after preparation of a test specimen.

If the initial foam height ratio is less than 6 times, the inside of the hollow body cannot be efficiently filled, and the object of the present invention cannot be achieved, which is not preferable. The upper limit of the expansion ratio is appropriately determined according to the purpose of use, but is generally 50 times or less, preferably 30 times or less. When the expansion ratio exceeds 50 times, the density of the foam decreases, and it may be difficult to satisfy requirements such as heat insulation, vibration proof, sound proof, and mechanical strength.

The foam sealant of the present invention is characterized in that the decrease in the expansion ratio over time is small,
The foaming height after storage for 7 days has an initial 50% or more, preferably 60 to 120%. If the foaming height after storage is less than 50% of the initial value, the reduction of the foaming ratio is large, and a thicker product is required to fill the inside of the hollow body having a predetermined height. In addition, such a low-foamed product may not be able to obtain a foam having a sufficient level of heat insulating properties and sound absorbing properties.

Thus, even if the rubber-based foam is manufactured and stored for a long period of time or is left in an environment where a temperature is applied, particularly in summer, the foaming of the sealing material can be performed without deteriorating the foaming performance. Can be.

The vulcanized high-foaming sealing material of the present invention is filled with a hollow body component such as the interior of a pillar of an automobile, and imparts heat insulation, vibration proofing, soundproofing, mechanical strength and the like to the hollow body. It can be suitably used in fields such as home electric appliances, industrial machines, and home building materials in addition to vehicle applications. In particular, since there is little decrease in foaming performance over time, it can be stored for a long period of time, and it is not necessary to pay much attention to the storage environment.

[0035]

The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Example 1 Styrene-butadiene rubber (styrene content 48%) as a rubber polymer, sulfur as a vulcanizing agent, iron dimethyldithiocarbamate and tetramethylthiuram monosulfide as a vulcanization accelerator, and azodicarbonamide as a foaming agent Used and other additives were blended in the number of parts shown in Table 1, and a pressure kneader was used.
To obtain a mixture, which was molded with an extruder to produce a vulcanized high foamed sheet. This sheet is 4mm high x
The test piece was cut into a width of 30 mm and a length of 80 mm.

Example 2 A styrene-butadiene-styrene elastomer (styrene content 25%) as a rubber polymer, sulfur as a vulcanizing agent,
Using dimethyldithiocarbamate iron, tetramethylthiuram monosulfide and tetraethylthiuram disulfide as the vulcanization accelerator, azodicarbonamide as the blowing agent, and other additives in the number of parts shown in Table 1, were blended in the same manner as in Example 1. To obtain a test body.

Example 3 Butadiene elastomer as a rubber polymer, sulfur as a vulcanizing agent, iron dimethyldithiocarbamate as a vulcanization accelerator,
Using azodicarbonamide as tetramethylthiuram monosulfide and a foaming agent, other additives were blended in the number of parts shown in Table 1, and a test specimen was obtained in the same manner as in Example 1.

Example 4 Styrene-butadiene rubber (styrene content 48%) as a rubber polymer, sulfur as a vulcanizing agent, copper dimethyldithiocarbamate and tetramethylthiuram monosulfide as a vulcanization accelerator, and azodicarbonamide as a foaming agent Used and other additives were blended in the number of parts shown in Table 1, and a specimen was obtained in the same manner as in Example 1.

Comparative Example 1 Styrene-butadiene rubber (styrene content 48%) as a rubber polymer, sulfur as a vulcanizing agent, tetramethylthiuram monosulfide as a vulcanization accelerator, azodicarbonamide as a foaming agent, and other additives The product was blended in the number of parts shown in Table 1, and a test body was obtained in the same manner as in Example 1.

Comparative Example 2 Styrene-butadiene-styrene elastomer (styrene content 25%) as a rubber polymer, sulfur as a vulcanizing agent,
Using tetramethylthiuram monosulfide and tetraethylthiuram disulfide as the vulcanization accelerator, azodicarbonamide as the foaming agent, and other additives in the number of parts shown in Table 1, the test pieces were obtained in the same manner as in Example 1. Was.

Comparative Example 3 A butadiene elastomer was used as a rubber polymer, sulfur was used as a vulcanizing agent, tetramethylthiuram monosulfide and tetraethylthiuram disulfide were used as vulcanization accelerators, and azodicarbonamide was used as a foaming agent.
And the test pieces were obtained in the same manner as in Example 1.

Comparative Example 4 Styrene-butadiene rubber (styrene content 48%) as a rubber polymer, sulfur as a vulcanizing agent, iron dimethyldithiocarbamate as a vulcanization accelerator, azodicarbonamide as a foaming agent, and other additives Was blended in the number of parts shown in Table 1, and a specimen was obtained in the same manner as in Example 1.

Evaluation method: height 4 mm × width 30 mm obtained in the above Examples and Comparative Examples
× A test piece having a length of 80 mm was subjected to an expandability test. The results are shown in Table 1.

(Initial foaming height) height 4 mm x width 30 mm
× 160 ° C within 1 day after preparing a test piece 80 mm long
For 15 minutes, and vulcanized and foamed. At this time, the height (maximum value) in the thickness direction of the specimen was measured, and the expansion ratio was determined from the ratio to the initial value.

(Foaming Height After Storage) The test specimen was stored in a thermostat at 60 ° C. for 7 days, and then the expansion ratio was determined in the same manner as the initial foaming height.

[0047]

[Table 1]

As shown in Table 1, in Examples in which iron dimethyldithiocarbamate and / or copper dimethyldithiocarbamate and thiurams were used in combination as vulcanization accelerators,
The initial expansion ratio is 6 times or more and 60 ° C.
And the foaming height after storage for 7 days was also 60% of the initial value, indicating that good foaming performance was maintained. In contrast, in Comparative Examples, when iron dimethyldithiocarbamate and copper dimethyldithiocarbamate were not used as the vulcanization accelerator (Comparative Examples 1 to 3), the foaming height after storage at 60 ° C. for 7 days was 60% of the initial value. The foaming performance is significantly reduced. When thiurams are not used as the vulcanization accelerator (Comparative Example 4), the initial expansion ratio is 6 times or less, which is not preferable.

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Claims (4)

[Claims] 1. A vulcanization-type high-foaming sealing material which is affixed inside a hollow body in an unfoamed state, and is vulcanized and foamed by heating to fill the inside of the hollow body, comprising a rubber-based polymer and a sulfur-based vulcanized material. , A vulcanization accelerator and a foaming agent, and the vulcanization accelerator contains at least iron dimethyldithiocarbamate and / or copper dimethyldithiocarbamate and thiurams, and is measured under the following conditions. Has a foaming height magnification of at least 6 times and a
A vulcanized high-foamed sealing material characterized in that the foaming height after storage for days is 50% or more of the initial level. (1) Specimen height 4 mm × width 30 mm × length 80 mm (2) Foaming conditions Put into a 160 ° C thermostat for 15 minutes 2. The method according to claim 1, wherein said thiurams are blended in a ratio (weight ratio) of 0.5 to 20 with respect to a total amount of said iron dimethyldithiocarbamate and / or copper dimethyldithiocarbamate of 1. A vulcanized high-foaming sealing material according to item 1. 3. The vulcanization-type highly foamable sealing material according to claim 1, wherein the sulfur-based vulcanizing agent is sulfur. 4. The vulcanizable high foam sealing material according to claim 1, wherein the rubber-based polymer is a styrene-butadiene rubber, a styrene-butadiene-styrene elastomer or a butadiene elastomer.