JP2002146072A - Vulcanizable and foamable rubber-based composition and foam thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vulcanizable and foamable rubber-based composition capable of forming a low density EPDM-based foam having excellent watertightness while keeping flexibility advantageous for operation. SOLUTION: This vulcanizable and foamable rubber-based composition comprises a mixture including at least an EPDM, a vulcanizing agent, a foaming agent and a softener comprising 10-35 pts.wt. of a sticky polymer per 100 pts.wt. of the EPDM. This rubber-based foam comprises a vulcanized foam having density <=0.200 g/cm3 obtained by forming the composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber-based vulcanized foam composition which is capable of forming a low-density EPDM foam which is flexible and has excellent water stopping performance even at a low compression rate, and is suitable for sealing applications.

[0002]

2. Description of the Related Art Conventionally, various EPDM vulcanized foams are known, and are widely used as various sealing materials such as water stoppage based on their excellent cushioning property and compressibility. In the case of the water stoppage, it is advantageous to have excellent flexibility in view of the formability of the bent portion. However, in the conventional foam, when the flexibility is improved by using a large amount of a softening agent, there is a problem that the water blocking performance is reduced due to a decrease in compressive stress.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to develop a rubber-based vulcanized foam composition capable of forming a low-density EPDM foam having excellent water-stop performance while having flexibility advantageous for work.

[0004]

The present invention is characterized in that it comprises an EPDM, a vulcanizing agent, a foaming agent and a blend containing at least 10 to 35 parts by weight of a tackifier polymer per 100 parts by weight of EPDM as a softening agent. Rubber-based vulcanized foam composition and density formed by the composition 0.200 g / cm
It is intended to provide a rubber-based foam characterized by comprising not more than ³ vulcanized foams.

[0005]

According to the present invention, the low-density foam having a small cell size is made possible by softening with an adhesive polymer, and the properties such as cushioning property and compressibility due to the rubber properties of the EPDM foam are maintained. The foam can be given flexibility that is advantageous to the work, and the foam can be given a slight adhesiveness that maintains good handleability, and can be pressure-bonded to the material to be sealed through the slight adhesive force. EPDM showing high sealing performance even when the interface between the material and the sealing material is in good contact with each other and showing a high level of water stopping performance even in a low compression state of about 50 to 60%.
A system foam can be obtained.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION A rubber-based vulcanized foam composition according to the present invention comprises at least an EPDM, a vulcanizing agent, a foaming agent and a softener comprising 10 to 35 parts by weight of a tackifying polymer per 100 parts by weight of EPDM. Things. The EP
As the DM, one or more appropriate ethylene-propylene-diene rubbers can be used, and the type is not particularly limited. The Mooney viscosity (ML) is better than the adjustability of performance such as compressibility and miscibility due to rubber properties.
_{1 + 4} , 100 ° C) 5 to 30, especially 8 to 25 EPD
M can be preferably used.

As the vulcanizing agent, an appropriate one or two
More than one kind can be used, and there is no particular limitation. Examples include sulfur and sulfur compounds, selenium and magnesium oxide, lead monoxide and zinc oxide, organic peroxides and polyamines, P-quinone dioxime and P, P'-dibenzoylquinone dioxime. Examples thereof include oximes and nitroso compounds such as P-dinitrosobenzine, resins such as alkylphenol-formaldehyde resin and melamine-formaldehyde condensate, and ammonium salts such as ammonium benzoate.

Sulfur and sulfur compounds, particularly sulfur, can be preferably used from the viewpoint of physical properties such as durability due to the vulcanizability and foaming property of the obtained foam. The amount of the vulcanizing agent can be appropriately determined according to the vulcanizing efficiency based on the type of the vulcanizing agent. By the way, in the case of sulfur, 0.1 to 10 parts by weight, especially 0.5 to 5 parts by weight is used per 100 parts by weight of EPDM.

As the foaming agent, one or more suitable foaming agents can be used, and there is no particular limitation. Incidentally, examples thereof include inorganic foaming agents such as ammonium carbonate and ammonium hydrogen carbonate, sodium hydrogen carbonate and ammonium nitrite, sodium borohydride and azides. Also, fluorinated alkanes such as trichloromonofluoromethane and dichloromonofluoromethane, azobisisobutyronitrile and azodicarboxylic amide (ADC)
A) and organic foaming agents such as azo compounds such as barium azodicarboxylate.

Further, hydrazine compounds such as paratoluenesulfonylhydrazide, diphenylsulfone-3,3'-disulfonylhydrazide, 4,4'-oxybis (benzenesulfonylhydrazide) and allylbis (sulfonylhydrazide), ρ-toluylenesulfonyl semicarbazide And semicarbazide compounds such as 4,4'-oxybis (benzenesulfonylsemicarbazide);
Triazole-based compounds such as morpholyl-1,2,3,4-thiatriazole; N-nitroso such as N, N'-dinitrosopentamethylenetetramine and N, N'-dimethyl-N, N'-dinitrosoterephthalamide An organic foaming agent such as a system compound is also included.

Among them, ADCA can be preferably used in view of harmlessness. The foaming agent to be used may be heat-expandable fine particles in which a heat-expandable substance is encapsulated in microcapsules. The heat-expandable fine particles include commercially available products such as microspheres (trade name, manufactured by Matsumoto Yushi Co., Ltd.). The amount of the foaming agent can be appropriately determined according to the physical properties of the desired foam. Generally, 0.1 to 100 parts by weight, especially 0.5 to 50 parts by weight, especially 1 to 30 parts by weight, of a blowing agent is used per 100 parts by weight of EPDM.

As the softener, one or two or more polymers composed of a waxy substance having tackiness and the like are used. Above all, an adhesive paraffinic amorphous polymer, particularly an adhesive ethylene / propylene copolymer, can be preferably used from the viewpoint of miscibility and the like. The compounding amount of the softening agent composed of such an adhesive polymer is EPDM100
It is 10 to 35 parts by weight per part by weight. If the compounding amount is less than 10 parts by weight, the adhesiveness is poor, and the water stopping performance in a low compression state is reduced. If the compounding amount is more than 35 parts by weight, the foam size increases due to a decrease in the viscosity of the admixture and the foam density increases. It is difficult to form a low-foamed foam.

The preparation of the admixture is carried out by an appropriate method such as a method of mixing at least a compounding component comprising EPDM, a vulcanizing agent, a foaming agent and the above-mentioned softener through a kneader such as a kneader or a mixing roll. It can be performed by mixing. At this time, a mixing method in which the temperature is raised to such an extent that vulcanization proceeds is not preferable. When preparing the admixture, an appropriate compounding agent according to the related art can be added as necessary for the purpose of adjusting the viscosity and vulcanizability, adjusting the physical properties such as the strength of the obtained foam, and the like.

For the purpose of accelerating vulcanization, for example, one or two of guanidines, thiazoles, sulfenamides, turams, dithiocarbamic acids, xanthogenic acids, aldehyde ammonias, aldehyde amines, thioureas, etc. The above-described vulcanization accelerator and further a vulcanization acceleration aid can be blended. The amount of the vulcanization accelerator used is suitably from 0.1 to 10 parts by weight per 100 parts by weight of EPDM, but is not limited thereto.

Contrary to the aforementioned vulcanization accelerator, organic acids such as phthalic anhydride, benzoic acid and salicylic acid, N-nitroso-diphenylamine, N -Nitroso-phenyl-β-
One or two of amines such as naphthylamine
More than one type of vulcanization retarder may be included.

Further, the admixture includes foaming aids such as urea, salicylic acid and benzoic acid, talc and clay, calcium carbonate and mica powder, zinc white and bentonite, carbon black and silica, alumina and aluminum silicate, and acetylene black. Fillers such as aluminum and aluminum powder, processing oils such as paraffins and petroleum oils, lubricants such as stearic acid and its esters, inorganic or organic flame retardants such as aluminum hydroxide and magnesium hydroxide, and others , Antioxidants and antioxidants, pigments and colorants,
One or more suitable compounding agents such as a fungicide can be added as necessary.

In addition, the above-mentioned zinc white is useful as a stabilizer, and carbon black is also useful as a reinforcing agent. Therefore, it is mentioned as an example of a component which can also contain various stabilizers and reinforcing agents. The above-mentioned processing oil and lubricant may function as a softening agent, so that the compounding amount is the total amount of the agents exhibiting the softening action from the viewpoint of maintaining the properties of the softening agent composed of the adhesive polymer described above. EPDM1 based on
It is preferably 150 parts by weight or less, more preferably 100 parts by weight or less, particularly preferably 80 parts by weight or less, per 100 parts by weight.

Further, a non-rubber-based polymer or EPD is used for the purpose of adjusting physical properties such as strength of the obtained foam.
One or more rubber-based polymers other than M can be blended if necessary. As the non-rubber-based polymer or rubber-based polymer, an appropriate one can be used,
There is no particular limitation. Incidentally, examples of the non-rubber-based polymer include acrylic polymers such as poly (meth) acrylates, urethane-based polymers, polyethylene and polypropylene, ethylene-vinyl acetate copolymers and polyvinyl acetates, polyamides, polyesters, and styrenes. Polymer, silicone polymer, epoxy resin and the like. The amount of EPDM used is preferably 50% by weight or less, more preferably 30% by weight or less, particularly preferably 15% by weight or less, for maintaining the rubber-like properties of the foam.

On the other hand, examples of rubber-based polymers other than the above-mentioned EPDM include α-olefins such as butene-1.
Rubber-based copolymer or ethylene-propylene rubber containing a cyclic or acyclic polyene having a non-conjugated double bond such as dicyclopentadiene or ethylidene norbornene,
Ethylene-propylene terpolymer, silicone rubber,
Polyurethane rubber, polyamide rubber, natural rubber, polyisobutylene, polyisoprene, chloroprene rubber,
Butyl rubber, nitrile butyl rubber, styrene / butadiene rubber, styrene / butadiene / styrene rubber, styrene / isoprene / styrene rubber, styrene / ethylene /
Examples include butadiene rubber, styrene / ethylene / butylene / styrene rubber, styrene / isoprene / propylene / styrene rubber, and acrylic rubber. The amount of the rubber-based polymer other than EPDM can be the same as in the case of the non-rubber-based polymer.

The rubber-based foam can be formed by heating and vulcanizing and foaming the above mixture. When forming the mixture, if necessary, the mixture may be formed into a predetermined form such as a sheet, and the formed body may be subjected to a heat treatment to form a vulcanized foam. In that case, the molded body may be formed into an arbitrary form by an appropriate method, and the form is not particularly limited. Therefore, the object of the vulcanization and foaming treatment may be a mixture obtained by molding the mixture into a sheet or other form by an appropriate method such as a mixing roll, a calender roll, or extrusion molding, or through a predetermined mold. It may be molded into a predetermined form having irregularities or the like by an appropriate method such as injection molding or press molding.

In the formation of the foam having the irregular shape, the unvulcanized sheet is placed on a mold having irregularities and heated, and the admixture for forming the unvulcanized sheet flows into the irregularities of the mold. A vulcanization and foaming method may be employed. Such a method has an advantage that the uneven shape can be accurately formed even in the case of a mold having a complicated and deep uneven structure having a fold structure. Therefore, the size of the molded article is arbitrary, and can be appropriately determined according to the intended form of the vulcanized foam. In the case of a sheet or the like, the thickness is 100 mm or less, preferably 1 μm to 80 mm, particularly 10 μm.
μm to 50 mm is common.

The above-mentioned vulcanization / foaming treatment can be carried out under appropriate conditions according to the prior art, depending on the vulcanization starting temperature and the foaming temperature of the used vulcanizing agent or foaming agent. General vulcanization foaming temperature is 450 ° C or less, especially 100-350 ° C,
Particularly, it is 120 to 300 ° C. Usually, the vulcanization and foaming treatment softens the admixture and expands the foaming agent to form a foamed structure, and vulcanization proceeds to form a desired vulcanized foam.

In the above, the foaming treatment and the vulcanization treatment can be performed under different temperature conditions, and appropriate treatment conditions can be adopted. The vulcanization / foaming treatment can also be performed under pressure for the purpose of adjusting the expansion ratio. The pressurization condition is
It can be according to the conventional. The expansion ratio (density ratio before and after foaming) of the vulcanized foam to be formed is appropriately determined according to the purpose of use and the like, but is generally 1.1 to 25 times, especially 1.5 times.
More than twice, especially 5 to 20 times.

The rubber foam which can be preferably used as a sealing material, particularly, a sealing material for waterproofing, has a foam cell size of about 1 to 1.5 mm and a density of 0.200 g / cm ³ or less. It is vulcanized and foamed so as to be 0.10 to 0.15 g / cm ³ . The density can be adjusted by the above-mentioned expansion ratio or the like, and the expansion ratio can be controlled by the amount of the above-mentioned foaming agent, vulcanization and foaming treatment time or temperature, and the like. It is also possible to control the foaming structure such as independent or continuous vulcanized foam obtained by adjusting the expansion ratio or the like, or a mixture thereof.

The rubber-based vulcanized foam composition of the present invention or a rubber-based foam using the same can be used for sealing, cushioning, padding, heat insulating, and other objects for various purposes such as airtightness and waterproofing.
As a vibration-reducing material such as soundproofing and vibration suppression, it can be preferably used in various fields, such as indoor products such as home appliances, outdoor products such as automobiles, and buildings such as houses, in various fields according to the related art. Especially, since it is excellent in workability due to flexibility or sealing performance in a low compression state due to workability and crimpability, it can be preferably used as a sealing material for water stoppage for the purpose of preventing water leakage.

[0026]

Example 1 100 parts of EPDM having a Mooney viscosity of 21 (parts by weight, the same applies hereinafter), an adhesive polymer (UT35, manufactured by Ube Lexen Co., Ltd.)
35: A tacky amorphous polymer composed of an ethylene / propylene copolymer having a melt viscosity at 190 ° C. of 15
100 cps, same hereafter) 10 parts, calcium carbonate 1
30 parts, 30 parts of processing oil (PW380, manufactured by Idemitsu Kosan Co., Ltd.)
10 parts of SFR carbon, 5 parts of zinc white and 3 parts of powdered stearic acid were mixed in a Banbury mixer at 130 to 140 ° C for 1 part.
The mixture was kneaded for 2 minutes, and 1.5 parts of fine sulfur powder and 3.5 parts of a vulcanization accelerator (Nouchira EZ: 2 manufactured by Ouchi Shinko Chemical Co., Ltd.) were added to the kneaded material.
Parts, Noxeller M: 1.5 parts), 15 parts of ADCA, and 10 parts of urea-based foaming aid, and further kneaded with a mixing roll to obtain an admixture, which is formed by an extruder and has a thickness of 5 mm.
The unvulcanized unfoamed sheet is heated for 30 minutes in a dryer at 160 ° C. and vulcanized and foamed to obtain a foamed sheet in which open cells and closed cells are mixed, and the skin layer on the surface is sliced. Thus, a rubber-based vulcanized foam having a foam cell size of 1 to 1.5 mm and a density of 0.11 g / cm ³ was obtained.

Example 2 The foamed cell size was 1 to 1.5 mm and the density was 0.1% according to Example 1, except that the amount of the adhesive polymer was 20 parts and the amount of calcium carbonate was 180 parts. 11 g / cm ³
To obtain a rubber-based vulcanized foam.

Example 3 The foamed cell size was 1 to 1.5 mm and the density was 0.1% according to Example 1 except that the amount of the adhesive polymer was 30 parts and the amount of calcium carbonate was 180 parts. 12g / cm ³
To obtain a rubber-based vulcanized foam.

Comparative Example 1 The foamed cell size was 1 to 1.5 mm and the density was 0.10 g / cm, according to Example 1, except that the adhesive polymer was not blended.
³ was obtained.

Comparative Example 2 The same procedure as in Example 1 was carried out except that the amount of the sticky polymer was changed to 5 parts, and the foamed cell size was 1 to 1.5 mm and the density was 0.1%.
A rubber-based vulcanized foam of 0 g / cm ³ was obtained.

Comparative Example 3 Example 1 was repeated except that the amount of the adhesive polymer was changed to 40 parts.
A rubber-based vulcanized foam having a foamed cell size of 1.5 to 2.0 mm and a density of 0.23 g / cm ³ was obtained according to the procedure described in Example 1.

Comparative Example 4 Example 1 was repeated except that the amount of the adhesive polymer was changed to 50 parts.
A rubber-based vulcanized foam having a foamed cell size of 1.5 to 2.0 mm and a density of 0.28 g / cm ³ was obtained in accordance with the above.

Evaluation Test The rubber-based vulcanized foams obtained in Examples 1 to 3 and Comparative Examples 1 and 2 were subjected to a U-shaped waterproof test to evaluate the water stopping performance. This indicates that the rubber-based vulcanized foams obtained in Examples 1 to 3 and Comparative Examples 1 and 2 have substantially the same cell size, density, and flexibility, and show the same level of sealing performance in appearance. It depends. In addition, those obtained in Comparative Examples 3 and 4 were not subjected to the test because the viscosity of the mixture was low, the foam cell size was large, the density was high, and the quality was inferior to those of the other examples.

In the U-shaped waterproof test described above, a U-shaped sample having a width of 10 mm is punched out of a rubber-based vulcanized foam having a thickness of 10 mm, and the formed sample is compressed to a predetermined compression ratio via a spacer between acrylic plates. Then, water was injected into the U-shaped portion of the sample so that the water head height became 50 mm, and it was visually observed whether or not water leaked within 24 hours, and the minimum compression ratio at which water leak did not occur was examined. The lower the compression ratio, the better the water stopping performance.

The results are shown in the following table. It can be seen from the table that water leakage can be prevented in a low compression state of 50% in Example 3 and 60% in Examples 1 and 2.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F074 AA25 AA97 AC02 AC21 AC26 AD09 AG01 AG03 AG11 AG20 BA13 BA28 BB05 BB27 CA29 CD08 DA02 DA03 DA39 4H017 AA03 AB07 AC04 AC13 AD06 AE03 4J002 BB151 BB152 CC053 CC183 DA046 DA116 DE207 DE106 DE217 DF037 DK007 EB067 EG076 EK006 EQ017 EQ027 EQ037 ER017 ES006 ES016 EU167 FD022 FD143 FD146 FD327 GJ02

Claims (3)

[Claims] 1. EPDM, vulcanizing agent, blowing agent and EPDM
A rubber-based vulcanized foam composition comprising a blend containing at least a softener consisting of an adhesive polymer in an amount of 10 to 35 parts by weight per 100 parts by weight. 2. The method according to claim 1, wherein the softener is ethylene.
A rubber-based vulcanized foam composition comprising a propylene-based copolymer. 3. A rubber foam comprising a vulcanized foam having a density of 0.200 g / cm ³ or less formed by the rubber vulcanized foamed composition according to claim 1 or 2.