JPH11106543A - Foamed rubber product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain foamed rubber product showing an excellent water sealing by compounding a rubber component containing not less than a specific amount of a copolymer from an ethylene, an α-olefin and a polyene having a nonconjugated diene double bond and a water-repellent and adhesive resin softener with a filler, a foaming agent and an vulcanizing accelerator and then curing the mixture so that the mixture will penetrate a clearance of a structure for close contact. SOLUTION: A foamed rubber product showing improved water sealing is designed so as to have a foaming ratio of 3-30 times, preferably 8-20 times, a diameter of a foam of not less than 15/inch, preferably not less than 30/inch, a compression stress at 50% compression of 5-200 gf/cm<2> , preferably 10-100 gf/cm<2> , air permeability of 100-2,000 cc/min, preferably 300-800 cc/min to have a proper ratio of continuous foams. A foamed rubber item is obtained by mixing 50-100 pts.wt. of a resin softener such as a paraffin oil, a polybutene, a rosin, etc., with 100 pts.wt. of a rubber component containing not less than 30 wt.% of a copolymer (EDPM) followed by compounding the obtained mixture with a filler, a foaming agent and a vulcanizing agent and continuously extruding thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber foam, and more particularly, to a rubber foam when installed in a void or a connection portion of a structure such as construction, civil engineering, vehicles, electric equipment, and housing equipment.
An object of the present invention is to provide a rubber foam for a foam seal material which easily follows and adheres to irregularities on the surface and exhibits excellent water stopping performance.

[0002]

2. Description of the Related Art Conventionally, as foams which follow and adhere to irregularities on the surface only by giving a relatively small compressive deformation, for example, EPDM systems of open cells having a high expansion ratio disclosed in JP-B-59-11613 are disclosed. Foams are known. However, if the amount of the adhesive material is too large, the Mooney viscosity is too low, and the kneading and molding processability are poor, and gas is easily released during foaming. Difficult to get. On the other hand, if the open cell ratio or the compressive stress is too high, the water stopping performance is reduced, and the followability of irregularities on the surface of the sealed material is reduced.

[0003] A polyurethane foam impregnated with a softened bitumen material to fill the cells of the foam is also disclosed. However, even with this impregnated foam, at least 80% is required to obtain the above-mentioned effects. And the drawback that bitumen oozes out during compression, weather resistance, cold resistance, chemical resistance, poor recovery, and high absorbency.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a rubber foam which solves the above-mentioned drawbacks of the prior art, and is excellent in moldability and processability of a compound, and further, for example, is mounted in a void or a connection portion of a structure. In this case, the present invention provides a rubber foam for a foam seal material which easily adheres to and adheres to irregularities on the surface thereof and exhibits excellent water stopping performance.

[0005]

SUMMARY OF THE INVENTION The present invention has the following configuration to improve the above-mentioned drawbacks. That is, a rubber component 10 containing at least 30 parts by weight of a copolymer composed of ethylene, α-olefin and a cyclic or non-cyclic polyene having a non-conjugated double bond alone or at least 30 parts by weight of the copolymer (EPDM)
0 parts by weight, 50 to 100 parts by weight of a water-repellent and tacky resin softener are essential components, and a filler, a foaming agent, a vulcanizing agent, a vulcanization accelerator and the like are mixed and kneaded, and the ML _{1 + 4}
(100 ° C.) is a foam obtained by continuously extruding and vulcanizing a foamed vulcanizable composition having a foaming ratio of 10 to 30 and foaming to a foaming ratio of 5 to 30 times. Stress is 5-200 gf / cm ² , air permeability is 100-2
000 cc / min.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the rubber foam of the present invention, not only the selection of the base material of the rubber foam but also a particularly preferable stop is specified by specifying its expansion ratio, cell diameter, air permeability and compressive stress. The present invention has been found to exhibit water performance and has led to the present invention. As for the high water-stopping property, it is required that it has good followability to the unevenness of the surface to be sealed and that the compressive stress has little strain dependency. This means that the higher the foaming ratio and air permeability,
The lower the compressive stress, the better.

In a rubber foam, the water stopping performance at a low compression ratio is improved as the cell diameter is smaller, that is, as the water passage is smaller. However, there is a limit in producing a foam having a high expansion ratio and a small cell diameter. There is. On the other hand, the water stopping performance under high water pressure is defeated by the water pressure even if the compressive stress is too low or the foaming ratio is too high, and the water stopping performance deteriorates. Furthermore, the high water-stopping performance is also important for the adhesion to the water-stopping material, and it is important not to create defects at the interface between the water-stopping material and the water-stopping material. For this reason, the smaller the bubble diameter and the lower the compressive stress, the fewer defects as a water-stopping material.

In view of these circumstances, in order to improve the water stopping performance comprehensively, it is necessary to have an appropriate expansion ratio, an appropriate compressive stress, a small cell diameter, and an appropriate air permeability, in other words, an appropriate open cell rate. Have been found to be effective for water stopping performance, and have reached the present invention. And, as a rubber foam optimized for a waterproof seal, its expansion ratio is 5 to 30 times,
It is preferably 8 to 20 times, and the bubble diameter is 15 times.
Pcs / inch or more, preferably 20 pcs / inch or more, more preferably 25 pcs / inch or more, most preferably 30 pcs / inch or more, and a 50% compressive stress of 5 to 200 gf /
cm ² , more preferably 10 to 100 g / cm ²
It is. And the air permeability is 100-2000cc / m
in, preferably those 200~1000cc / cm ^2, it should be one more preferable to satisfy each of these conditions in that for highly exhibit the waterproofing performance as 300 to 800 / cm ^2.

[0009] Incidentally, regarding the air permeability, the bubble diameter,
Assuming that the compressive stress and the compressive strain rate are constant, in the case of air permeability, in other words, in the case of a moderate open cell rate, the open cell portion is more greatly deformed than the closed cell portion. Therefore, as the open cell rate becomes higher than the above-mentioned range, the deformation of each open cell portion decreases, so that the defect becomes large and the water stopping performance becomes inferior.

When the rubber foam is subjected to compression deformation and used as a water-stopping material for a long time in that state, EP is excellent in weather resistance as a rubber component and hardly causes stress cracks due to aging.
Compositions containing DM alone or a component such as butyl rubber containing at least 30% by weight or more of EPDM in the total rubber component are preferred.

The EPDM is a terpolymer composed of ethylene, propylene or butene-1 and the polyene monomers listed below. Examples of the polyene monomer include dicyclopentadiene,
-5-cyclooctadiene, 1.1-cyclooctadiene, 1.6-cyclododecadienes, 1.7-cyclododecadienes, 1.5.9-cyclododecatriene, 1.4
-Cycloheptadiene, 1,4-cyclohexadiene,
Norbornadiene, methylene norbornene, 2-methylventadiene-1.4, 1.5-hexadiene, 1.6
Heptadiene, methyl-tetrahydroindene, 1.
4-hexadiene and the like.

[0012] Since the foamed water-stopping material is used in a compressed state for a long period of time, EPDM having good heat resistance and weather resistance is particularly selected. Furthermore, the effect of suppressing cracks against stress caused by compressive deformation. Is a characteristic that cannot be obtained by other than EPDM, and 30 parts by weight of EPDM of the rubber component is required to exhibit such characteristics.

[0013] Such EPDM is described later in Mooney.
In consideration of the scotch time, it is desirable that the grade of EPDM used has a low viscosity and an iodine value of 20 or less. As a commercial product that can be adapted to this,
EP22 manufactured by Nippon Synthetic Rubber Co., Ltd., 30 manufactured by Mitsui Petrochemical Co., Ltd.
45H and 501A manufactured by Sumitomo Chemical Co., Ltd. and the like.

On the other hand, rubber components used together with EPDM include EPM and IIR having good weather resistance and compatibility, as well as IR, NR, SBR, BR, RB (1,2-polybutadiene), ACM and ANM. , CSM, CR, silicone rubber, etc., and preferably EPM, IIR.

The water-repellent and tacky resin softener added to the rubber component may be a foamed material for a rubber foam, having a Mooney viscosity ML _{1 + 4} (100 ° C.) of 10 to 30,
Preferably, it functions to adjust the viscosity to a low value of 12 to 20, and the rubber foam formed in the form of a sheet and foamed and vulcanized is highly flexible and increases the adhesion to the surface to be sealed. In addition, it is a prerequisite for having sufficient recoverability as a water stopping material after compression deformation.

The composition of the present invention, which is a foamed material of a rubber foam, comprises a resin softener, a foaming agent, a vulcanizing agent, a vulcanization accelerator, and a vulcanization accelerator, which are water repellent and tacky with the rubber component. And a known compounding agent such as a filler, a coloring agent, an antioxidant, etc., by a conventional method.

As such a water-repellent and tacky resin softening agent, 50 to 100 parts by weight of at least one of paraffin oil, blow-asphalt, polybutene and rosin are required based on 100 parts by weight of a rubber component. This is because EPDM has good compatibility with EPDM and gives adhesion without contaminating the water-stopping material by bleed from a rubber foam. If the amount is less than 50 parts by weight, a foam having a high expansion ratio, appropriate air permeability, appropriate flexibility, etc. cannot be obtained. If the amount exceeds 100 parts by weight, kneading and molding processability deteriorate, and In addition, the rubber foam obtained from this composition has poor breaking strength, elongation, poor settability, etc., too high air permeability, too large cell diameter, or too low compressive stress to give a favorable state. Absent. Further, the secondary workability such as slicing and punching of the rubber foam is also reduced, so that accurate processing cannot be performed.

The foaming agent is used not only for generating gas for foaming but also for controlling the vulcanization of rubber.
For example, dinitropentamethylenetetramine (DP
T), azodicarbonamide (ADCA), 4, 4'-
Oxybisbenzenesulfonyl hydrazide (OBS
H) There are sodium bicarbonate and the like, but ADCA has the effect of delaying the vulcanization of rubber,
It is suitable for obtaining chi time. The thermal decomposition temperature of ADCA is relatively high, and a decrease in the decomposition temperature has an effect on zinc white and the like. Preferably, a foaming auxiliary such as urea is used in combination.

Examples of the vulcanizing agent include sulfur, magnesium oxide, zinc white, P-quinone dioxime and the like. As the vulcanization accelerator, thiazoles, dithiocarbamates, thioureas, dithiophosphites, thiurams and the like may be suitably combined. Specific examples of other compounding agents, for example, as a vulcanization accelerator, stearic acid, lauric acid, etc., as a filler, calcium carbonate,
Clay, talc, asbestos, recycled rubber, ceramic,
Glass fibers, wood flour, fiber waste, etc., other coloring agents, anti-aging agents and the like are appropriately selected and blended.

Of the foamed vulcanizable composition for obtaining a rubber foam, particularly important is the Mooney viscosity (10%).
0 ° C., ML _{1 + 4} ), and the range is 10 to 30, preferably 12 to 20. In terms of the Mooney viscosity, it is premised that the foamed vulcanizable composition has a low viscosity in order to obtain a highly foamed and flexible foam, but if the viscosity of the composition is too low. Kneading, causing problems in moldability, outgassing during foam vulcanization results in too high air permeability or flat plate shape, too large cell diameter, or too low compressive stress. . On the other hand, if the viscosity of the composition is too high, a foam having a high expansion ratio cannot be obtained, or gas escape or cracking occurs during foam vulcanization. It becomes too foamy. For this reason, the present invention has been particularly specified in the above-mentioned limited range.

The characteristic rubber foam of the present invention is obtained by controlling the foam vulcanization reaction.
That is, the balance between the thermal decomposition of the foaming agent and the rubber vulcanization is the most important. If the decomposition of the foaming agent precedes the rubber vulcanization, outgassing occurs in the foaming process, resulting in a low expansion ratio, high air permeability, and The shape becomes unfavorable. On the other hand, if the rubber vulcanization reaction precedes the decomposition of the foaming agent, the closed cell ratio in the foam increases, and a high expansion ratio cannot be obtained,
A foam with poor flexibility results. Further, when trying to obtain a thick foam, the foam is broken or the cell diameters are different between the surface and the inside, so that the desired foam cannot be obtained.

In order to control the balance between the decomposition of the foaming agent and the rubber vulcanization to obtain a characteristic rubber foam, in addition to specifying the Mooney viscosity of the foamed vulcanizable composition, −
It is important to specify the scotch time, and the scotch time is preferably at least 20 minutes, preferably at least 30 minutes, and it has been found that it is difficult to obtain a characteristic foam below this time. In particular, when obtaining a thick extruded foam vulcanizable composition, that is, a thick rubber foam, it is important to specify the Mooney-Scotch time. As described above, it is important to select EPDM, a vulcanization accelerator and a foaming agent in order to obtain a characteristic moon scotch time in the foamed vulcanizable composition.

Usually, a hot air heating furnace is used for normal pressure continuous foaming. However, as the thickness of the extruded rubber of the foamed vulcanizable composition increases, the temperature difference between the rubber surface and the inside of the rubber increases. It is difficult to obtain a foam. This means that the faster the vulcanization reaction, the greater the difference in vulcanization between the rubber surface and the inside. Therefore, if the composition has a thickness of 15 mm or more, the Mooney scotch time is 45%. It is more preferred that the time be at least minutes. In order to reduce the difference in vulcanization between the rubber surface and the inside during the foam vulcanization, it is effective to change the temperature of the heating furnace from a low temperature to a high temperature, for example, to perform heating. Good to do.

The extruded thickness of the foamed vulcanizable composition is 15
mm or more, the thickness of the foam is 30 to 100 mm,
Slicing or slicing / crushing such foam,
At least one side is coated with a pressure-sensitive adhesive and a release paper is pasted to form a tape-shaped foam sealing material mainly having water-stopping performance, which is then used for vehicles such as wind dams, air conditioners, and washing machines. Refrigerators, vending machines and other electrical equipment, acoustic equipment, outer wall joints, sashes, construction of roof joints, etc., kitchen equipment, unit baths, household equipment such as water heaters, structural seals It can be widely used as a foam sealing material for civil engineering such as materials, joints of roads and bridges, and waterway joints.

[0025]

The present invention will be described below in more detail with reference to examples. (Production method of rubber foam) In the composition according to Table 1,
A compounding agent excluding a foaming agent, a foaming aid, a vulcanizing agent and a vulcanization accelerator is kneaded with a kneader. At this time, the temperature of the kneaded material needs to be 100 ° C. or higher to disperse the compounding agent and to disperse moisture, and the kneading is usually performed at 120 ° C. for 8 minutes. After the kneaded product has cooled, a predetermined amount of a foaming agent, a foaming aid, a vulcanizing agent, and a vulcanization accelerator are added, and the mixture is kneaded with a kneader (8).
(0 ° C. × 5 minutes) to obtain a foamed vulcanizable composition. Next, this was formed into a sheet having a thickness of 20 mm by a rubber extruder, and this was placed in a heating furnace (140 ° C. × 80 minutes) and vulcanized and fired.
A rubber foam was obtained.

In Table 1, EPDM (1) is a trade name of 3045H manufactured by Mitsui Petrochemical Company, EPDM (2) is a trade name of 501A manufactured by Sumitomo Chemical Co., Ltd., and EPDM (3) is a trade name of EP33 manufactured by Nippon Synthetic Rubber Co., Ltd. The blowing agent ADCA is azodicarbonamide. In the composition shown in the table, general compounding agents such as zinc white and stearic acid are omitted. Table 1 also shows the properties of the foamed vulcanizable composition and the properties of the obtained rubber foam.

[0027]

[Table 1]

(Test Method) Among the test methods showing the characteristics of the rubber foam, the 50% compressive stress test method was performed in accordance with JIS K6767.

FIG. 1 shows the outline of the air permeability test method. Thickness (a) 10mm, outer shape (b) 80mm, inner diameter (c) 6
Rubber foam sample S ₁ having a donut shape of 0 mm
The obtained by punching, which in acrylic plate 3 provided with perforations 2 in the center in the container 1 performs 50% compression, air at a pressure of 20mmHg from samples S ₁ side in this state - the supply, air exits from the center of the sample S ₁ - amount of (cc / min) was measured as air permeability characteristics.

FIG. 2 shows an outline of a water column test method by a water stoppage test. Thickness (a) 10mm and diameter (d) 30m
punched rubber foam samples S ₂ of m, the lower surface to the sample S ₂ adhesive tape of transparent acrylic cylinder 4 (inner diameter 20 mm, outer 30 mm) - affixed at-flop or the like, a defined amount into the cylindrical body 4 Of water, and a water column height (mm) (h ₁ ) after 8 hours without water leakage is measured.

FIG. 3 shows an outline of a U-shaped test method by a water stoppage test. Thickness (a) 10mm, width (e) 10m
m, height (f) 130 mm, distance (g) between both ends 45
mm in a U-shape to form a rubber foam sample S ₃
Is obtained by two acrylic plates 5 and 6 in the thickness direction.
It compresses by 0%, puts a specified amount of water in the U-shape, and measures the water depth (mm) (h ₂ ) after 8 hours without water leakage.

(Evaluation of Rubber Foam) Each of the examples satisfies the conditions specified in the present invention, and has properties suitable for using the rubber foam as a water-stopping material. In Comparative Example 1, outgassing occurred during foam vulcanization, and a rubber foam having a high expansion ratio was not obtained. Comparative Example 2
The kneading and molding workability is poor and is not practical. Further, in Comparative Example 3, cracking occurred during foaming.

[0033]

As described above, according to the present invention, a rubber which has a relatively small compressive deformation in a void portion having a different void size of a structure, adheres closely to the uneven surface thereof, and particularly exhibits a water stopping performance. A foam was obtained, and a rubber foam having various effects such as windproof performance and soundproof performance could be provided.

[Brief description of the drawings]

FIG. 1 shows an outline of a test method for air permeability.

FIG. 2 shows an outline of a water column test method by a water stoppage test.

FIG. 3 shows an outline of a U-shaped test method by a water stoppage test.

[Explanation of symbols]

S ₁ , S ₂ , S ₃ ‥‥ Rubber foam sample.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 23:16

Claims (6)

[Claims] 1. A copolymer consisting of ethylene, an α-olefin and a cyclic or noncyclic polyene having a nonconjugated double bond alone or 100 parts by weight of a rubber component containing at least 30 parts by weight of the copolymer, water repellency and adhesion. Resin softener 50-
100 parts by weight as an essential component, and a filler, a foaming agent, a vulcanizing agent, a vulcanization accelerator and the like are mixed and kneaded, and foaming with a Mooney viscosity ML _{1 + 4} (100 ° C.) of 10 to 30 is performed. A foam obtained by continuously extruding a vulcanizable composition and foaming and vulcanizing to expand the foamable composition to a foaming ratio of 5 to 30 times.
50% compressive stress of 5 to 200 gf / cm ² , air permeability of 1
A rubber foam characterized by being in the range of 00 to 2000 cc / min. 2. The rubber foam according to claim 1, wherein the water-repellent and tacky resin softener is selected from paraffin oil, polybutene, blown asphalt and rosin. 3. The multi-core composition of the foamed vulcanizable composition.
Chitaimu (120 ℃, t ₅₎ is a rubber foam first of claims is at least 20 minutes. 4. The rubber foam according to claim 1, wherein said foaming agent is azodicarbonamide. 5. A copolymer comprising ethylene, an α-olefin and a cyclic or non-cyclic polyene having a non-conjugated double bond alone or having an iodine value of 20 or less and having a mu-viscosity ML _{1+ 4.} The rubber foam according to claim 1, wherein (100 ° C.) is 45 or less. 6. The rubber foam according to claim 1, wherein the foamed vulcanizable composition has an extrusion molding thickness of 15 mm or more, and the foam has a thickness of 30 to 100 mm.