JP2000159953A - Rubber expanded material and sealing material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject material having excellent heat resistance, a large expansion ratio, and a low specified gravity and also having a tackiness on the surface, and useful as a sealing material by using ethylene-propylene based copolymer rubber as a rubber component. SOLUTION: This expanded material is obtained by expanding and crosslinking a rubber composition containing (A) an ethylene-α-olefin based copolymer rubber, (B) an organic peroxide and (C) a forming agent (preferably azodicarbonamide) in a hot air. A specific gravity of the objective expanded material is <=0.2 and the component A is ethylene-α-olefin copolymer rubber or ethylene-α-olefin-nonconjugated diene copolymer rubber and especially the α-olefin is propylene and the nonconjugated diene is 5-ethylidene-2-norbornene or dicyclopentadiene, and preferably the component B is contained in an amount of 0.5-25 pts.wt. and the component C is contained in an amount of 3-53 pte.wt. to 100 pts.wt. of the component A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a rubber foam and a sealing material. More specifically, the present invention provides:
Ethylene-propylene copolymer rubber as the rubber component,
Excellent heat resistance, and has a characteristic that the expansion ratio is large and low specific gravity, for example, building civil engineering, electrical equipment, automobiles, vehicles, ships, joints of structures such as housing equipment,
When attached to a gap or the like, a rubber foam that follows and adheres to the unevenness of the surface of the partner only by applying a relatively small compressive stress, thereby exhibiting excellent waterproof, windproof, soundproof and dustproof properties, And a sealing material using the rubber foam. Further, since the surface of the rubber foam after foaming / crosslinking has adhesiveness, the adhesive surface portion can be used to improve the adhesion of the seal portion.

[0002]

2. Description of the Related Art So-called sealing materials to be attached to joints and gaps of structures such as architectural civil engineering, electric equipment, automobiles, vehicles, ships, housing equipment, etc., are provided with waterproofness, windproofness, and the like.
It is required to be excellent in so-called sealing performance such as soundproofing and dustproofing, and to be excellent in heat resistance, weather resistance and ozone resistance.

[0003] By the way, it is known that ethylene-α-olefin copolymer rubber represented by ethylene-propylene-non-conjugated diene copolymer rubber has excellent weather resistance and ozone resistance. Japanese Patent Publication No. 59-11613 discloses a rubber foam (sponge rubber) obtained by vulcanizing and foaming ethylene-propylene-non-conjugated diene copolymer rubber using sulfur. However, there is a problem that the rubber foam obtained by this method is inferior in heat resistance.

[0004]

Under such circumstances, the problem to be solved by the present invention is to use an ethylene-propylene copolymer rubber as a rubber component, to have excellent heat resistance, to have a large expansion ratio and to have a low specific gravity. Yes, and because it has the characteristic of having a sticky surface, building civil engineering, electrical equipment, automobiles, vehicles, ships, joints of structures such as housing equipment,
When attached to a gap or the like, a rubber foam that follows and adheres to the unevenness of the surface of the partner only by applying a relatively small compressive stress, thereby exhibiting excellent waterproof, windproof, soundproof and dustproof properties, Another object of the present invention is to provide a sealing material using the rubber foam.

[0005]

That is, the first invention of the present invention is obtained by foaming / crosslinking a rubber composition containing the following (A) to (C) in hot air, It relates to a rubber foam having a specific gravity of 0.3 or less. (A): ethylene-α-olefin copolymer rubber (B): organic peroxide (C): foaming agent

The second invention of the present invention relates to a rubber foam which foams and crosslinks in a hot mold in the presence of air, instead of foaming and crosslinking in hot air in the first invention. It is.

The third invention of the present invention relates to a sealing material using the rubber foam of the first invention or the second invention.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The ethylene-α-olefin copolymer rubber as the component (A) of the present invention is ethylene-α-olefin.
Olefin copolymer rubber or ethylene-α-olefin-non-conjugated diene copolymer rubber.

Examples of the α-olefin include propylene, 1-butene, 1-pentene, 1-hexene,
-Methyl-1-pentene, 1-octene, 1-decene and the like, among which propylene and 1-butene are preferred.

Non-conjugated dienes include, for example, 1,4
-Hexadiene, 1,6-octadiene, 2-methyl-
Linear non-conjugated dienes such as 1,5-hexadiene, 6-methyl-1,5-heptadiene, 7-methyl-1,6-octadiene; cyclohexadiene, dicyclopentadiene, methyltetraindene, 5-vinylnorbornene 2,3-diisopropylidene-5; cyclic unconjugated dienes such as, 5-ethylidene-2-norbornene, 6-chloromethyl-5-isopropylenyl-2-norbornene
-Norbornene, 2-ethylidene-3-isopropylidene-5-norbornene, 2-propenyl-2,2-norbornadiene, 1,3,7-octatriene, 1,4,
Trienes such as 9-decatriene; or 5-vinyl-
2-norbornene, 5- (2-propenyl) -2-norbornene, 5- (3-butenyl) -2-norbornene,
5- (4-pentenyl) -2-norbornene, 5- (5
-Hexenyl) -2-norbornene, 5- (5-heptenyl) -2-norbornene, 5- (7-octenyl)-
2-norbornene, 5-methylene-2-norbornene,
6,10-dimethyl-1,5,9-undecatriene,
5,9-dimethyl-1,4,8-decatriene, 4-ethylidene-8-methyl-1,7-nonadiene, 13-ethyl-9-methyl-1,9,12-pentadecatriene, 5,9, 13-trimethyl-1,4,8,12-tetradecadiene, 8,14,16-trimethyl-1,
7,14-hexadecatriene, 4-ethylidene-12
-Methyl-1,11-pentadecadiene, one of which may be used alone, or two or more of which may be used in combination. In addition, 5-ethylidene-2-norbornene and / or 5-ethylidene-2-norbornene and dicyclopentadiene are preferable.

The component (A) of the present invention, ethylene-α-
The method for producing the olefin-based copolymer rubber is not particularly limited, and it can be produced using various catalysts such as a titanium-based catalyst, a vanadium-based catalyst, and a metallocene-based catalyst.

The ratio (molar ratio) of ethylene / α-olefin in (A) is usually 1 / (0.1 to 1).
For the non-conjugated diene, the ratio (molar ratio) of ethylene / non-conjugated diene is usually 1 / (0.005 to 0.2).
It is.

The Mooney viscosity of (A) at 121 ° C. is usually from 5 to 200, preferably from 20 to 180. If the Mooney viscosity is lower than this, it may be difficult to make a cold flow of the compound, it may be difficult to make a ribbon for continuous ribbon feeding to the molding machine, and there may be defective phenomena such as the shape of the extruded product collapses. If the ratio is high, productivity may be deteriorated in manufacturing.

The component (B) of the present invention is an organic peroxide.

As for (B), the one-minute half-life temperature is 160
Organic peroxide alone having a temperature of less than 1 ° C or a one-minute half-life temperature of 1
An organic peroxide having a temperature of less than 60 ° C and a one-minute half-life temperature of 1
A mixture of an organic peroxide having a temperature of 60 ° C. or higher is preferable from the viewpoint of maintaining the shape of the foam during foaming / crosslinking in hot air. Examples of the organic peroxide having a one-minute half-life temperature of less than 160 ° C. include 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, benzoyl peroxide, and t-butylperoxyisopropyl carbonate. And so on. As an organic peroxide having a one-minute half-life temperature of 160 ° C. or higher,
Dicumyl peroxide, 2,5-dimethyl 2,5-bis (t-butylperoxy) hexane and the like can be mentioned.

[0016] The content of (B) per 100 parts by weight of (A) is preferably 0.5 to 25 parts by weight, more preferably 1 to 10 parts by weight. If the amount of (B) is too small, the crosslinking is not sufficiently performed, and the mechanical properties of the foam may be deteriorated. On the other hand, if the amount of (B) is too large, the crosslinking precedes,
It may not foam or the foam may burst during foaming.

The component (C) of the present invention is a blowing agent.

As (C), azodicarbonamide,
Examples thereof include dinitrosopentamethylenetetramine, and azodicarbonamide is preferable from the viewpoint of safety of generated gas and safety in handling.

The content of (C) per 100 parts by weight of (A) is preferably from 3 to 35 parts by weight, more preferably from 10 to 20 parts by weight. If the amount of (C) is too small, the expansion ratio of the foam may be small. On the other hand, if the amount of (C) is too large, the shape of the foam may be distorted during foaming / crosslinking in hot air, or the foam may burst. Or you may.

In the present invention, the above (A) to (C)
In addition, the following (D) to (E) can be used.

Component (D) is a reinforcing agent and / or filler.

Examples of the reinforcing agent include carbon black, silica and the like.

Examples of the filler include calcium carbonate, clay, talc and the like.

The content of (D) per 100 parts by weight of (A) is preferably 30 to 300 parts by weight, more preferably 70 to 200 parts by weight. If (D) is too small, the processability of the rubber composition may deteriorate, while if (D) is too large, the mechanical properties of the foam may deteriorate.

Component (E) is a process oil.

Examples of (E) include paraffinic oils, naphthenic oils, and aromatic oils.

As (E), ASTM D 3238
% C by -85 (ndM method) _AIs less than or equal to 2
This is preferable from the viewpoint of sufficiently crosslinking the foam.
The% C_AIs too large, the foam is sufficiently crosslinked.
In some cases, the physical properties of the foam may deteriorate.

The content of (E) per 100 parts by weight of (A) is preferably 30 to 250 parts by weight, more preferably 50 to 150 parts by weight. If the content of (E) is too small, the processability of the rubber composition may deteriorate, while if the content of (E) is too large, the rubber composition may lose its shape during molding.

In the present invention, in addition to the above components,
As the component (F), 2-mercaptobenzimidazole and / or poly (2,2,4-trimethyl-1,2-dihydroquinoline) can be used.

[0030] The content of (F) per 100 parts by weight of (A) is preferably 0.5 to 25 parts by weight, more preferably 1 to 10 parts by weight. If the amount of (F) is too small, the shape of the foam may be lost at the time of foaming / crosslinking in hot air, while if the amount of (F) is too large, the foam may not be sufficiently crosslinked, and Physical properties of the body may deteriorate.

The rubber foam of the present invention has the above (A) to
It is obtained by foaming / crosslinking a rubber composition containing (C) in hot air, and preferably (A) to (A).
It is obtained by foaming and cross-linking the rubber composition containing the above (D) to (F) in addition to (C) in hot air. The quantitative ratio of each component is as described above.

In the present invention, the Mooney scorch time (JIS-K-6300) of the rubber composition before foaming / crosslinking is used.
-T of the ML at 120 ° C. in the Mooney Scorch test
5 is preferably 30 minutes or less from the viewpoint of increasing the foaming (that is, low specific gravity) of the foam obtained by foaming and crosslinking in hot air.

A specific method for obtaining a foam by foaming / crosslinking in hot air is as follows.
Components (A) to (C) and, if necessary, components (D) to
(F), if necessary, zinc oxide, stearic acid, polyethylene glycol, calcium oxide, foaming aid, crosslinking aid, antioxidant, sulfur, vulcanization accelerator, adhesive substances such as polybutene and rosin, components The rubber other than (A) is kneaded using a Banbury or a kneader and a roll to obtain a rubber composition. Next, a foam is obtained by foaming and crosslinking the rubber composition in hot air. As an apparatus at this time, an oven, a continuous hot air crosslinking apparatus, or the like can be used. The conditions for foaming and crosslinking are as follows:
At 0 ° C. for 10-60 minutes, and then at a temperature of 140-20
Two-stage heating at 0 ° C. for 10 to 60 minutes can be mentioned. Here, when foaming / crosslinking in hot air, the heating conditions are divided into at least two stages.
Heating at 0 to 130 ° C. for 10 minutes or more is preferable from the viewpoint of making the foam highly foamed (ie, low specific gravity).

In the present invention, instead of foaming / crosslinking in hot air, foaming / foaming is performed in a hot mold in the presence of air.
By crosslinking, a rubber foam having a specific gravity of 0.3 or less can be obtained. Foaming in a hot mold in the presence of air
A specific method for obtaining a foam by crosslinking is as follows. Components (A) to (C), optionally components (D) to (F), and optionally zinc oxide,
Stearic acid, polyethylene glycol, calcium oxide, foaming aid, crosslinking aid, anti-aging agent, sulfur, vulcanization accelerator, adhesive substances such as polybutene and rosin, component (A)
Other rubbers are kneaded using a Banbury or a kneader and a roll to obtain a rubber composition. Next, the rubber composition is foamed and crosslinked in a hot mold in the presence of air by heating by contact heat conduction or radiant heat from the mold to obtain a foam. The heating mold temperature and heating time are two-stage heating in which the heating mold temperature is heated at 90-130 ° C. for 10-60 minutes, and then the heating mold temperature is heated at 140-200 ° C. for 10-60 minutes. Can be given. Here, at the time of foaming / crosslinking in a hot mold in the presence of air, the heating conditions are divided into at least two stages, and one of the conditions is that the temperature of the hot mold is 90 to 130 ° C. and heating is performed for 10 minutes or more. But,
It is preferable from the viewpoint of making the foam highly foamed (that is, low specific gravity). In addition, the temperature of the hot mold refers to the temperature of the mold surface where the rubber composition to be foamed and crosslinked comes into contact.

The rubber foam of the present invention is obtained by foaming and crosslinking in a hot mold in hot air or in the presence of air using an organic peroxide. This makes it possible to obtain a rubber foam having excellent heat resistance and adhesiveness on the surface. When the surface has adhesiveness, the sealing performance can be further improved when the surface is used in contact with the sealing portion. The air in the hot air and the air in the hot mold in the presence of the air mainly use air, and other gases such as nitrogen and carbon dioxide may be additionally mixed.

The rubber foam of the present invention has a specific gravity of 0.3
Or less, preferably 0.2 or less. If the specific gravity is excessive, it will be unsatisfactory in that it will adhere to and adhere to the surface of the mating surface only by applying a relatively small compressive stress, thereby exhibiting excellent waterproofing, windproofing, soundproofing and dustproofing properties. .

The rubber foam of the present invention can be used as a sealing material or a sound-absorbing material to be used by being attached to joints or gaps of structures such as construction civil engineering, electric equipment, automobiles, vehicles, ships, and housing equipment. It can be optimally applied as a heat insulator, foam roll.

[0038]

Next, the present invention will be described by way of examples.

Examples 1 to 10 and Comparative Example 1 The compositions shown in Tables 1 to 3 were mixed using a Banbury and a roll to obtain a foamable and crosslinkable rubber composition. Next, the rubber composition is continuously extruded using an extruder, followed by hot air heating (two-stage heating or hot air heating at a hot air temperature of 120 ° C. for 40 minutes and then a hot air temperature of 160 ° C. for 40 minutes). The mixture was foamed and cross-linked by heating at a temperature of 170 ° C. for 30 minutes for 30 minutes to obtain a rubber foam having a rectangular parallelepiped shape having a cross section of about 50 mm in height, about 120 mm in width and about 500 mm in length. Next, the surface adhesion state and shape deformation of the rubber foam were evaluated and shown in Tables 4 to 6.
Next, measurement and evaluation were performed on the items described in Tables 4 to 6,
The results are shown in Tables 4 to 6.

Example 11 A rubber composition capable of being foamed and crosslinked was obtained by mixing the formulations shown in Table 3 using a Banbury and a roll. Next, the rubber composition is heated in a hot mold in the presence of air (at a hot mold temperature of 120 ° C. for 40 minutes and then at a hot mold temperature of 16 ° C.).
Foaming / crosslinking by two-stage heating at 0 ° C for 40 minutes or one-stage heating at 160 ° C for 40 minutes.
Height about 50mm, width about 120mm, length about 150m
m was obtained. Next, the surface adhesion state and shape deformation of the rubber foam were evaluated, and the results are shown in Table 6. Next, measurement and evaluation were performed for the items described in Table 6,
The results are shown in Table 6.

[0041]

[Table 1]

[0042]

[Table 2]

[0043]

[Table 3]

[0044]

[Table 4]

[0045]

[Table 5]

[0046]

[Table 6]

(Explanation of the table) ・ Blank is not measured ・ Expansion crosslinking temperature condition (1): Two-stage heating at a hot air temperature of 120 ° C. for 40 minutes and then at a hot air temperature of 160 ° C. for 40 minutes ・ Expansion crosslinking temperature condition (2): 30 at hot air temperature of 170 ° C
One-stage heating for 1 minute ・ Foam crosslinking temperature condition (3): 40 at hot mold temperature of 120 ° C
For two minutes at a hot mold temperature of 160 ° C for 40 minutes. ・ Foam crosslinking temperature condition (4): 40 at a hot mold temperature of 160 ° C
One-step heating for 1 minute ・ The hot air heating condition of the rubber foam used for the evaluation items other than the rubber foam specific gravity is the foam crosslinking temperature condition (1). (A): EPDM: ethylene-propylene-5-ethylidene-2-norbornene copolymer rubber (ethylene /
Propylene molar ratio = 1.0 / 0.67, ethylene / 5
-Ethylidene-2-norbornene molar ratio = 1.0 /
(Moony viscosity at 0.018 and 121 ° C. = 32) ・ (D) -1: Carbon black: “Asahi 50HG” manufactured by Asahi Carbon Co., Ltd. ・ (D) -2: Calcium carbonate ・ (C): Foaming manufactured by Sankyo Chemical Co., Ltd. "Cellmic C-1" azodicarbonamide-Foaming aid: Urea-based foaming aid "Selton NP" manufactured by Sankyo Kasei Co., Ltd.-(E) -1: Process oil: Idemitsu Kosan's "PS4"
30, "ASTM D3238-85 (ndM method)
According% C _A 6.4-in (E) -2: process oil: manufactured by Idemitsu Kosan Co., Ltd. "PW3
80 ", ASTM D3238-85 (ndM method)
According% C _A is 0, the (B) -1: dicumyl peroxide, (B) -2: 1,1-bis (t-butylperoxy)
3,3,5-trimethylcyclohexane ・ Crosslinking aid-1: Ethylene glycol dimethacrylate ・ Crosslinking aid-2: N, N′-m-phenylenebismaleimide ・ (F) -1: Poly (2,2,4) -Trimethyl-1,2
-Dihydroquinoline)-(F) -2: 2-mercaptobenzimidazole -Vulcanization accelerator: SoxPZ, Sox manufactured by Sumitomo Chemical Co., Ltd.
Mixture of EZ, SoxM

[0048]

As described above, according to the present invention, an ethylene-propylene copolymer rubber is used as a rubber component, and has excellent heat resistance, a large expansion ratio, a low specific gravity, and an adhesive property on its surface. Because it has the feature of building civil engineering, electrical equipment, automobiles, vehicles, ships, joints of structures such as house equipment, gaps, etc. A rubber foam that adheres closely to irregularities and thus exhibits excellent waterproof, windproof, soundproof, and dustproof properties, and a sealing material using the rubber foam can be provided.

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 4F074 AA25A AC02 AC26 AC32 AD01 AD19 AD21 AG01 BA13 BA16 BB04 CA25 CC04Y CC07Y CC22X DA02 DA32 DA39 DA57 4J002 AE052 BB151 DA038 DE238 DJ018 DJ038 DJ048 EK036 EK046 EK0 000 EK FE FE FE FE GJ02

Claims (17)

[Claims] 1. A rubber foam having a specific gravity of 0.3 or less, obtained by foaming and crosslinking a rubber composition containing the following (A) to (C) in hot air. (A): ethylene-α-olefin copolymer rubber (B): organic peroxide (C): foaming agent 2. The rubber foam according to claim 1, which has a specific gravity of 0.2 or less. 3. The rubber foam according to claim 1, wherein (A) is an ethylene-α-olefin copolymer rubber or an ethylene-α-olefin-nonconjugated diene copolymer rubber. 4. The rubber foam according to claim 1, wherein the α-olefin of (A) is propylene. 5. The rubber foam according to claim 3, wherein the non-conjugated diene of (A) is 5-ethylidene-2-norbornene or dicyclopentadiene. 6. An organic peroxide having a one-minute half-life temperature of less than 160 ° C. or a one-minute half-life temperature of 160 ° C.
Organic peroxide which is less than 100 ° C. and a one-minute half-life temperature of 160
The rubber foam according to claim 1, wherein an organic peroxide having a temperature of not less than ° C is mixed. 7. The rubber foam according to claim 1, wherein (C) is azodicarbonamide. 8. The content of (B) per 100 parts by weight of (A) is 0.5 to 25 parts by weight, and the content of (C) per 100 parts by weight of (A) is 3 to 35 parts by weight. The rubber foam according to claim 1, which is a part. 9. The rubber foam according to claim 1, wherein a rubber composition containing (A) to (C) according to claim 1 and the following (D) to (E) is used. (D): reinforcing agent and / or filler (E): process oil 10. The method according to claim 1, wherein (E) is ASTM D 3238-
85 rubber foam according to claim 9 wherein (n-d-M method) According% C _A is 2 or less process oil. 11. The content of (D) per 100 parts by weight of (A) is 30 to 300 parts by weight, and (A) 100
The rubber foam according to claim 9, wherein the content of (E) is 30 to 250 parts by weight per part by weight. 12. The rubber foam according to claim 1, containing (A) to (C) according to claim 1 and the following (F), or (A) to (C) and claim according to claim 1. (D) described in 9
The rubber foam according to claim 1, which comprises (E) to (E) and the following (F). (F): 2-mercaptobenzimidazole and / or poly (2,2,4-trimethyl-1,2-dihydroquinoline) 13. The method according to claim 1, wherein the heating condition is divided into at least two stages when foaming / crosslinking in hot air, and one of the conditions is heating at a temperature of 90 to 130 ° C. for 10 minutes or more. A rubber foam according to one of the claims. 14. The rubber composition before foaming and crosslinking, wherein the Mooney scorch time (ML120 ° C. in JIS-K-6300-Mooney scorch test) t5 is 30 minutes or less. The rubber foam according to claim 1. 15. The method according to claim 1, wherein foaming / crosslinking is performed in a hot mold in the presence of air instead of foaming / crosslinking in hot air.
The rubber foam according to any one of claims 12 to 14. 16. When foaming / crosslinking in a hot mold in the presence of air, the heating conditions are divided into at least two stages, one of which is heating at a temperature of the hot mold of 90 to 130 ° C. for 10 minutes or more. The rubber foam according to claim 15, which is to do. 17. A sealing material using the rubber foam according to any one of claims 1 to 16.