JP2003238726A - Rubber foam - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber foam which has an ethylene-propylene based copolymer rubber as the rubber component, and has good surface smoothness, profile designing properties, sealing properties, sound absorbing qualities, heat retaining properties, electrical resistance stability, compression durability, and stabilities of various performances as a sealing medium, joint compound, sound absorbing material, heat reserving material (thermal insulating material), cushioning medium, rolling material, and the like, in the fields of constructions and public works, electrical apparatuses, automobiles, vehicles, ships, housing facilities equipment, and the like, due to its possession of, as characteristic features, excellent heat resistance, weatherability, and ozone resistance, the lightness in weight and, simultaneously, the very fineness in cell diameter. <P>SOLUTION: This rubber foam can be obtained by foaming and crosslinking a rubber composition comprises at least (A) an ethylene-α-olefin copolymer rubber, (B) a blowing agent, and (C) a vinyl chloride based resin which is a vinyl chloride based polymer having an average particle diameter of 0.1-10 μm in an aqueous dispersion, and has an average cell diameter of 1-150 μm. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a rubber foam. More specifically, the present invention relates to a rubber foam having an ethylene-propylene copolymer rubber as a rubber component, which is excellent in heat resistance, weather resistance and ozone resistance, is lightweight, and has extremely fine cells.

[0002]

2. Description of the Related Art Used as a sealing material, joint material, sound absorbing material, heat insulating material (heat insulating material), cushioning material, roll material, etc. in the fields of construction civil engineering, electric equipment, automobiles, vehicles, ships, housing equipments, etc. The rubber foam is required to have excellent heat resistance, weather resistance, and ozone resistance, as well as the surface smoothness of the foam,
In order to improve the cross-sectional design, sealability, sound absorption, heat retention, electric resistance stability, compression durability, and various performance stability, it is required that the bubble diameter be fine. Ethylene-propylene represented by ethylene-propylene-non-conjugated diene copolymer rubber
-Olefin copolymer rubber is known to have excellent heat resistance, weather resistance, and ozone resistance. However, a rubber foam obtained by foaming / crosslinking a rubber composition containing an ethylene-α-olefin copolymer rubber usually has a large cell diameter and tends to be non-uniform, resulting in rough surface skin. Therefore, there is a problem in that the appearance is deteriorated and various performances are deteriorated.

[0003]

Under these circumstances, the problem to be solved by the present invention is to use an ethylene-propylene copolymer rubber as a rubber component, which is excellent in heat resistance, weather resistance and ozone resistance and is lightweight. And the feature that the bubble diameter is extremely fine, it can be used for construction civil engineering, electrical equipment, automobiles,
Surface smoothness, cross-sectional design, sealability, sound absorption, heat retention as a sealing material, joint material, sound absorbing material, heat insulating material (heat insulating material), cushioning material, roll material, etc. in the fields of vehicles, ships, housing equipment, etc. The present invention is to provide a rubber foam having excellent stability, electric resistance stability, compression durability, and various performance stability.

[0004]

That is, the present invention is obtained by foaming / crosslinking a rubber composition containing at least the following components (A) to (C), and has an average cell diameter of 1 to 150 μm. The present invention relates to a rubber foam. (A): ethylene-α-olefin copolymer rubber (B): foaming agent (C): the vinyl chloride polymer in the aqueous dispersion has an average particle size of 0.1 to 10 μm. Vinyl chloride resin

[0005]

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

Examples of α-olefins include propylene, 1-butene, 1-pentene, 1-hexene and 4
-Methyl-1-pentene, 1-octene, 1-decene and the like can be mentioned, and among them, propylene and 1-butene are preferable.

As the non-conjugated diene, for example, 1,4
-Hexadiene, 1,6-octadiene, 2-methyl-
Chain non-conjugated dienes such as 1,5-hexadiene, 6-methyl-1,5-heptadiene, 7-methyl-1,6-octadiene; cyclohexadiene, dicyclopentadiene, methyltetraindene, 5-vinylnorbornene Cyclic non-conjugated dienes such as 5-ethylidene-2-norbornene, 6-chloromethyl-5-isopropenyl-2-norbornene; 2,3-diisopropylidene-5
-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 may be mentioned, and one of them may be used alone, or two or more thereof 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 or a metallocene-based catalyst.

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

The Mooney viscosity of (A) at 121 ° C. is usually 5 to 200, preferably 20 to 180. If the Mooney viscosity is lower than this, it may cause problems such as cold flow of the compound or difficulty in forming a ribbon for continuous ribbon feed to the molding machine, and defective phenomena such as collapse of the shape of the extrusion molded product. If the value is high, the productivity may be deteriorated in manufacturing.

The component (B) of the present invention is a foaming agent.

As (B), azodicarbonamide,
Azobisisobutyronitrile, dinitrosopentamethylenetetramine, 4,4'-oxybisbenzenesulfonyl hydrazide, sodium bicarbonate, sodium carbonate, ammonium bicarbonate, ammonium carbonate, ammonium nitrite, N, N'-dimethyl N, N ′ -Dinitron-terephthalamide, azocyclohexyl nitrile, azodiaminobenzene, barium-azodicarboxylate, benzene-sulfonyl-hydrazide, toluene-sulfonyl-hydrazide, diphenylsulfone-3,3′-disulfonyl-hydrazide, calcium azide , 4, 4'-
Examples thereof include diphenyl-disulfonyl azide-bala-toluene-malphonyl azide, and azodicarbonamide is preferable from the viewpoint of safety of generated gas and safety in handling.

The content of (B) per 100 parts by weight of (A) is preferably 3 to 35 parts by weight, more preferably 10 to 20 parts by weight. If the amount of (B) is too small, the expansion ratio of the foam may be small. On the other hand, if the amount of (B) is too large, the shape of the foam may collapse during foaming / crosslinking, or the foam may burst. is there.

Component (C) of the present invention is a vinyl chloride resin characterized in that the vinyl chloride polymer in the aqueous dispersion has an average particle size of 0.1 to 10 μm. When the average particle diameter of the component (C) is less than 0.1 μm, it becomes difficult to disperse the component (C) in the rubber composition, and a uniform rubber foam cannot be obtained. On the other hand, when the average particle diameter exceeds 10 μm, the average bubble diameter of the rubber foam increases.

The method for producing the vinyl chloride resin which is the component (C) of the present invention is not particularly limited.

(C) is a vinyl chloride homopolymer,
Examples thereof include copolymers of vinyl chloride and monomers copolymerizable therewith. As such a copolymerizable monomer,
For example, vinyl acetate, vinyl esters such as vinyl propionate, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, methyl acrylate, methyl methacrylate, unsaturated carboxylic acid esters such as ethyl itaconic acid, ethylene, Examples thereof include olefins such as propylene, vinyl ethers such as methyl vinyl ether and ethyl vinyl ether, fumaric acid, maleic acid, their anhydrides, and their esters.

The content of (C) per 100 parts by weight of (A) is preferably 10 to 100 parts by weight, more preferably 30 to 80 parts by weight. If (C) is too small, the average cell diameter of the rubber foam may not be sufficiently fine, while if (C) is too large, the foam may burst during foaming. In the present invention, the above (A)
In addition to (C), the following (D) to (E) can be used.

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

Examples of the reinforcing agent include carbon black and silica.

Examples of the filler include calcium carbonate, clay, talc, magnesium hydroxide, aluminum hydroxide, calcium silicate 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 the amount of (D) is too small, the processability of the rubber composition may deteriorate, while if the amount of (D) is excessive, the mechanical properties of the foam may deteriorate.

Component (E) is process oil.

Examples of (E) include paraffin oil, naphthene oil, and aromatic oil.

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 amount of (E) is too small, the processability of the rubber composition may deteriorate, while if the amount of (E) is too large, the rubber composition may lose its shape during molding.

The rubber foam of the present invention has the above-mentioned (A) to (A).
It is obtained by foaming / crosslinking a rubber composition containing (C), preferably a rubber composition containing the above (D) to (E) in addition to (A) to (C). It is obtained by foaming / crosslinking. The amount ratio of each component is as described above.

The rubber foam of the present invention has an average cell diameter of 1 to 150 μm, preferably 1 to 100 μm. If the bubble size is too small, the density of the rubber foam will not easily decrease, while if the bubble size is too large, the smoothness of the rubber foam surface will be impaired, and the sealing, sound absorption, heat retention, and electrical resistance will be stable. Property, compression durability, and various performance stability are reduced.
Here, the cell diameter was determined as the arithmetic mean value obtained by determining the diameter of each cell based on the photograph obtained by enlarging the cross section of the obtained rubber foam with a scanning electron microscope 55 times and dividing by the number of cells. It is a value.

The rubber foam of the present invention has a density of 0.2.
It is preferably g / cm ³ or less. If the density is too high, the rubber foam becomes unsatisfactory in terms of sealing properties, heat retaining properties, and cushioning properties.

A specific method for obtaining a foam by foaming / crosslinking is as follows. Ingredient (A)
~ (C), if necessary, components (D) to (E), and if necessary, zinc oxide, stearic acid, polyethylene glycol, calcium oxide, foaming aid, cross-linking agent, cross-linking aid,
An antiaging agent, sulfur, a vulcanization accelerator, an adhesive substance such as polybutene and rosin, a resin such as polyethylene and polypropylene, and a rubber other than the component (A) are kneaded using a Banbury or a kneader and a roll, and a rubber composition To get next,
A foam is obtained by foaming and crosslinking the rubber composition in hot air or the like. As an apparatus in this case, an oven, a continuous hot air crosslinking apparatus, a thermal mold, or the like can be used.
The conditions of foaming / crosslinking are 10 at a temperature of 90 to 130 ° C.
~ 60 minutes, then 10 at a temperature of 140-200 ° C
Two-step heating for up to 60 minutes can be mentioned. Here, at the time of foaming / crosslinking, heating conditions are divided into at least two stages, one of which is 10 at a temperature of 90 to 130 ° C.
Heating for more than a minute is preferable from the viewpoint of making the foam highly foamed (that is, low density).

The rubber foam of the present invention is used as a sealing material, joint material, sound absorbing material, heat insulating material (heat insulating material) in the fields of construction civil engineering, electric equipment, automobiles, vehicles, ships, housing equipment, etc.
It can be optimally applied as a cushioning material and a roll material.

[0030]

EXAMPLES Next, the present invention will be explained by examples. The particle size of the vinyl chloride resin is the laser diffusion type particle size distribution measuring device (Master Sizer MS
20).

Example 1 and Comparative Examples 1-2 The blends shown in Table 1 were mixed using a Banbury and a roll to give a foamable and crosslinkable rubber composition. Next, the rubber composition is continuously extruded using an extruder, followed by hot air heating (two-step heating at a hot air temperature of 120 ° C. for 40 minutes and then at a hot air temperature of 160 ° C. for 30 minutes). Was foamed and crosslinked to obtain a rectangular parallelepiped rubber foam having a cross-sectional dimension of about 50 mm in height, a width of about 120 mm, and a length of about 500 mm. Next, the items shown in Table 2 were measured, and the results are shown in Table 2.

[0032]

[Table 1]

[0033]

[Table 2]

(Explanation of Tables) (A) -1: EPDM: ethylene-propylene-5
-Ethylidene-2-norbornene copolymer rubber (molar ratio of ethylene / propylene = 1.0 / 0.67, molar ratio of ethylene / 5-ethylidene-2-norbornene = 1.0
/0.018, Mooney viscosity at 121 ° C = 32)-(A) -2: EPDM: ethylene-propylene-5
-Ethylidene-2-norbornene copolymer rubber (molar ratio of ethylene / propylene = 1.0 / 0.55, molar ratio of ethylene / 5-ethylidene-2-norbornene = 1.0
/0.056, Mooney viscosity at 121 ° C = 33) ・ (B): Sankyo Kasei's foaming agent "Celmic C-1"
Azodicarbonamide (C): Vinyl chloride resin having an average particle diameter of 1.3 μm (F): Vinyl chloride resin having an average particle diameter of 120 μm (D) -1: Calcium carbonate (D) -2 : Carbon black: "Asahi 50U" manufactured by Asahi Carbon Co., Ltd. (E): Process oil: "PS43 manufactured by Idemitsu Kosan Co., Ltd."
0 ”・ Foaming aid: Urea-based foaming aid" Selton NP "manufactured by Sankyo Kasei Co., Ltd. ・ Vulcanization accelerator: Sumitomo Chemical Co., Ltd. accelerators PZ, EZ,
Mixture of M

[0035]

As described above, according to the present invention, ethylene-propylene copolymer rubber is used as a rubber component, and it is excellent in heat resistance, weather resistance and ozone resistance, is lightweight, and has an extremely fine bubble diameter. Because of its characteristics, it is used in construction civil engineering, electrical equipment, automobiles, vehicles, ships, housing equipment, etc. in the fields of sealing materials, jointing materials, sound absorbing materials, heat insulating materials (heat insulating materials),
As a cushioning material, roll material, etc., surface smoothness, cross-sectional design,
It was possible to provide a rubber foam having good sealing properties, sound absorption properties, heat retention properties, electrical resistance stability, compression durability, and various performance stability.

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 4F074 AA25 AA35 AA76 AA97 AC02                       AC03 AC21 AC26 AD09 AG01                       BA13 BA28 BB01 BB05 CA25                       CC04Y CC06Y CC07Y DA03                       DA32 DA33 DA35 DA39 DA57                 4F212 AA09 AA15 AA45 AB02 AG20                       UA09 UB02 UC05 UC06 UF01                       UF21 UG03 UN09

Claims (6)

[Claims] 1. A rubber foam obtained by foaming and crosslinking a rubber composition containing at least the following components (A) to (C), and having an average cell diameter of 1 to 150 μm. (A): ethylene-α-olefin copolymer rubber (B): foaming agent (C): the vinyl chloride polymer in the aqueous dispersion has an average particle size of 0.1 to 10 μm. Vinyl chloride resin 2. The rubber foam according to claim 1, which has a density of 0.2 g / cm ³ or less. 3. The rubber foam according to claim 1, wherein (A) is an ethylene-α-olefin copolymer rubber or an ethylene-α-olefin-non-conjugated 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 (A) is 5-ethylidene-2-norbornene or dicyclopentadiene. 6. In foaming and crosslinking, heating conditions are divided into at least two stages, one of which is a temperature of 90 to 130.
The rubber foam according to claim 1, wherein the rubber foam is heated at 0 ° C. for 10 minutes or more.