JP2001322204A - Composite consisting of foamed rubber and rigid member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite consisting of foamed rubber and a rigid member capable of being made lightweight because extremely fine cells are included, excellent in surface smoothness and physical properties, and keeping dimensional stability while putting characteristics of foamed rubber to practical use. SOLUTION: The composite consists of the foamed rubber of which the cells has a mean cell size of 1-150 μm, the hardness measured by a spring type hardness test durometer type A (JIS-K-6253-1997) hardness meter is 30-90, and the denisity is 0.7-1.1 kg/1; and the rigid member of which the Young's modulus (E0) at 23 deg.C is 102-106 MPa.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite comprising foamed rubber and a rigid body. More specifically, the present invention is a composite composed of a foamed rubber and a rigid body, which has extremely fine bubbles, can be reduced in weight, and has excellent surface smoothness and physical properties. The present invention relates to a composite made of a foamed rubber and a rigid body while maintaining the dimensional stability while making the best use.

[0002]

2. Description of the Related Art For the purpose of reducing the weight of automobiles and reducing the number of materials, weight reduction of members has been studied for many materials, and even in the case of weatherstrip solid materials for automobiles, the weight has been reduced in response to recent demands for low fuel consumption. Efforts are being made to reduce it. Conventionally, in order to reduce the weight of such rubber materials, a method of reducing the mixing ratio of carbon black having a high density of itself or an inorganic filler in the compounding material, or a method of using oil with a high oil absorbing carbon black has been used. A method of increasing the addition ratio, a method of adding an ethylene resin such as a polyethylene resin, and the like have been used. In addition to these methods, studies are being made to make the solid portion a foam. However, the method of reducing the compounding ratio of carbon black and inorganic filler is that the processability of the rubber compound is reduced, the compounding cost is increased, and the oil addition ratio is increased by using highly oil-absorbing carbon black. However, there is a problem that the method of increasing the viscosity and the method of adding a material having a relatively low density such as polyethylene have a limit in the density of the obtained vulcanized rubber. In addition, the method of forming a solid portion into a foam has the advantage that the density of the obtained vulcanized rubber can be freely designed, but the surface is easily roughened, and the sealing function and appearance as a product are impaired, and the production and production It has been known that there is a problem that the dimensional change of the subsequent product is so large that the productivity does not increase, and that the stress and hardness of the rubber are reduced and the characteristics expected as a solid rubber are impaired.

[0003] The present inventors have studied in detail the technology of using solid rubber as a foam, and by using a foam having an average cell diameter in a specific range, the properties expected as a solid rubber are impaired. That the surface roughness can be prevented while maintaining the appearance similar to solid rubber while reducing weight, and that the dimensional change of the product can be suppressed to a minimum by combining the foam with the rigid body during production, It has been found that by setting the density and hardness of the obtained low-foam rubber in a specific range, it is possible to achieve both sufficient weight reduction and characteristics expected as a solid rubber.

A rubber composition for obtaining a low-foam rubber having a fine cell diameter is disclosed in, for example,
Japanese Patent Application Laid-Open No. -80459 discloses a technique. In this case, the technique is directed to a soft sponge material having an Asker C hardness of 40 or less. It is not a technology to reduce the weight by microbubbles while retaining the function. Also, a spring type hardness test durometer type A (JIS
-K-6253-1997) The hardness measured with a hardness meter (hereinafter referred to as JIS-Duro A type hardness meter) is 30 to 9.
There is no technical disclosure or suggestion for obtaining a low-expanded microcellular rubber having a hardness equivalent to that of a conventional solid rubber, such as in the range of 0.

[0005]

Under such circumstances,
The problem to be solved by the present invention is a composite comprising a foamed rubber and a rigid body, which has extremely fine bubbles, can be reduced in weight, and has excellent surface smoothness and physical properties. It is an object of the present invention to provide a composite made of a foamed rubber and a rigid body while maintaining the dimensional stability while utilizing the characteristics.

[0006]

That is, according to the present invention, an average cell diameter is from 1 to 150 μm, a hardness measured by a JIS-Duro A type hardness meter is from 30 to 90, and a density is from 0.7 to 90 μm. The present invention relates to a composite comprising a foamed rubber having a weight of 1.1 kg / L and a rigid body having a Young's modulus (E ₀ ) at 23 ° C. of 10 ² to 10 ⁶ MPa.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The rubber component of the present invention includes natural rubber, styrene butadiene rubber, acrylonitrile butadiene rubber, butadiene rubber, silicone rubber, chloroprene rubber, acrylic rubber, ethylene acrylic rubber, fluorine rubber, ethylene-α-olefin. Copolymer rubber, ethylene-α-olefin-non-conjugated diene copolymer rubber, and the like. From the viewpoint of heat resistance and weather resistance, ethylene-α-
Olefin-non-conjugated diene copolymer rubbers are preferred. These rubbers may be used alone or in combination of two or more.

The α-olefin of the ethylene-α-olefin-non-conjugated diene copolymer rubber includes, for example, propylene, 1-butene, 1-pentene, 1-hexene,
Examples thereof include 4-methyl-1-pentene, 1-octene, 1-decene and the like, and one kind thereof may be used alone, or two or more kinds may be used in combination. In addition, propylene and 1-butene are preferable from the viewpoint of availability.

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, from the viewpoint of availability, 5-ethylidene-2-norbornene and / or 5-ethylidene-2
-Norbornene and dicyclopentadiene are preferred.

The method for producing the ethylene-α-olefin-non-conjugated diene copolymer rubber is not particularly limited, and the rubber can be produced using various catalysts such as a titanium catalyst, a vanadium catalyst or a metallocene catalyst. .

The ratio (molar ratio) of ethylene / α-olefin is from 1 / (0.1 to 0.1) from the viewpoint of flexibility as a rubber.
1) is preferred, and the ratio (molar ratio) of ethylene / non-conjugated diene is 1 / (0.005 to 0.005 to 5) from the viewpoint of preventing burning at the die portion during extrusion molding and the degree of vulcanization of the obtained vulcanized rubber product.
0.2) is preferred, but not specified.

Solution viscosity [η] of ethylene-α-olefin-non-conjugated diene copolymer rubber (70 ° C. in xylene)
Is preferably from 0.2 to 10, more preferably from 0.5 to 4. If the viscosity is too low, the bubble diameter may be too large, whereas if the viscosity is too high, extrusion may not be possible. Ethylene-α-
As the olefin-non-conjugated diene copolymer rubber, a commercially available rubber can be used.

The foamed rubber of the present invention has an average cell diameter of 1 to 1
It is 50 μm, preferably 1 to 100 μm. If the average cell diameter is too small, the density of the foamed rubber is unlikely to decrease,
It is difficult to reduce the weight. On the other hand, if the cell diameter is too large, the smoothness of the foamed rubber surface is impaired. Here, the average cell diameter was obtained as an arithmetic average value obtained by calculating the diameter of each cell based on a photograph obtained by enlarging the cross section of the obtained foamed rubber by a scanning electron microscope at a magnification of 55 times and dividing by the number of cells. Value.

The foamed rubber of the present invention has a hardness of 30 to 90, preferably 40 to 80, as measured by a JIS-Duro A type hardness tester. If the hardness is too low, the strength as a seal rubber for automobiles becomes insufficient, and if the hardness is too high, the flexibility as a seal rubber for automobiles becomes insufficient.

The foamed rubber of the present invention has a density of 0.70 to 0.70.
1.10 kg / L, preferably 0.85 to 1.0
5 kg / L, more preferably 0.90 to 1.0 kg / L
It is. If the density is too low, the average cell diameter becomes larger than 150 μm, and the surface of the obtained rubber product may become defective or the physical properties may be reduced. On the other hand, if the density is too high, the weight reduction desired for the present invention cannot be achieved.

The foamed rubber of the present invention is preferably produced by a production method using a foaming agent having a decomposition temperature of 170 ° C. or higher as a foaming agent in the composition. Here, “use a foaming agent having a decomposition temperature of 170 ° C. or more as a foaming agent”
The expression means that a foaming agent having a decomposition temperature of less than 170 ° C. is not used, and the decomposition temperature of the foaming agent is not made lower than 170 ° C. by using a foaming aid represented by urea. Decomposition temperature 17
Examples of the foaming agent at 0 ° C. or higher include azodicarbonamide, dinitrosopentadienyltetramine and the like, and examples of the foaming auxiliary agent having a decomposition temperature of less than 170 ° C. include zinc oxide. The decomposition temperature of the foaming agent as used herein means that the rubber composition before foaming and vulcanization is measured using a thermogravimetric analyzer TAS-100 manufactured by Rigaku Corporation under an air stream at a heating rate of 10%.
It means the exothermic onset temperature of the DTA curve measured under the measurement conditions of ° C./min. The amount of the foaming agent is preferably 4 to 15 parts by weight, more preferably 5 to 10 parts by weight, per 100 parts by weight of rubber. If the amount is too small, the weight may not be reduced. On the other hand, if the amount is too large, the bubble diameter becomes too large and the surface of the obtained rubber product may be defective.

In producing the foamed rubber of the present invention, a reinforcing agent such as carbon black generally added to rubber in the so-called rubber industry, a softening agent such as process oil,
Inorganic fillers as extenders, liquid polybutadiene rubber, thermosetting processability improvers such as liquid isoprene rubber,
Various processing aids, tackifiers, sulfur, sulfur vulcanizing agents such as organic peroxides, various vulcanization accelerating aids, phthalic anhydride, benzoic acid,
Anti-scorch agents such as salicylic acid, malic acid and oxalic acid can be added. In addition, high-density polyethylene (H
DPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), ethylene-vinyl acetate copolymer resin (EVA), ethylene-acryl copolymer resin, ethylene-α-olefin copolymer resin, etc. Resins can also be added. The addition amount of the ethylene-based resin is preferably 1 to 40 parts by weight, more preferably 5 to 30 parts by weight, based on 100 parts by weight of rubber. If the used amount is too small, the hardness of the foamed rubber may not be sufficiently high, while if the used amount is too large, the bubble diameter may be too large and the surface of the obtained rubber product may be defective. .

The rubber compound used in the present invention can be prepared by using an ordinary rubber kneader, that is, a Banbury mixer, a kneader, or various closed kneaders, kneading extruders, or open rolls. The viscosity of the rubber compound obtained by mixing these various additives is determined by the Mooney viscosity (M
L _{1 + 4} , 100 ° C.) is preferably 30 to 160. If the Mooney viscosity is lower than this, the cell diameter becomes too large, and the resulting product tends to have poor appearance. If the Mooney viscosity is higher than this, molding in an extruder becomes difficult.

In producing the foamed rubber of the present invention, at least one of (liquid) polybutadiene rubber, polyisoprene rubber, and styrene-butadiene copolymer rubber is made of ethylene-α-olefin-non-conjugated diene copolymer rubber 100. It is preferable that 5 to 40 parts by weight and 3 to 15 parts by weight of sulfur as a vulcanizing agent are added to the parts by weight. If the content of at least one of (liquid) polybutadiene rubber, polyisoprene rubber and styrene-butadiene copolymer rubber is too small, the hardness of the foamed rubber may not be sufficiently high, while the content is too large. When,
The heat resistance and weather resistance of the foamed rubber may deteriorate. If the amount of sulfur is too small, the hardness of the foamed rubber may not be sufficiently high, while if the amount of sulfur is too large, the elongation of the foamed rubber may decrease or the appearance may be deteriorated due to bloom. is there.

In producing the foamed rubber of the present invention, it is preferable to blend at least one metal acrylate compound represented by the following chemical formula (1) into the rubber compound. This makes it possible to further enhance the adhesiveness to a metal as a rigid body when producing the composite of the foamed rubber of the present invention and the rigid body. (Wherein, R represents a hydrogen atom or a methyl group, and M represents 1-3
Represents a valent metal atom, x represents an integer of 1 to 3, and y represents 0
Represents an integer of ２2. )

M in the above formula (1) represents a metal atom having a valence of 1 to 3, and specific examples thereof include lithium, sodium, potassium, magnesium, calcium, strontium, barium, manganese, iron, cobalt, and nickel. , Copper, silver, zinc, aluminum and the like. Specific examples of the metal acrylate compound include zinc acrylate, magnesium acrylate, aluminum hydroxide acrylate, zinc methacrylate, magnesium methacrylate, and aluminum hydroxide methacrylate. As the metal acrylate compound, one kind thereof may be used alone, or two or more kinds thereof may be used in combination.

The amount of the metal acrylate compound used is 0.1 to 50 parts by weight, preferably 1 to 10 parts by weight, per 100 parts by weight of the rubber component. If the amount is too small, the above-mentioned adhesive strength may be insufficient. On the other hand, if the amount is too large, the mechanical properties of the foamed rubber may decrease.

The composite of the present invention comprises the above foamed rubber and 23
Young's modulus at ° C. (E ₀₎ is a complex consisting of a rigid body is 10 ² ~10 ⁶ MPa.

Examples of the rigid body include metals such as iron (including steel and cast iron), aluminum, magnesium, copper, tin, nickel, gold, and silver, and materials containing these metals as main components, and stainless steel alloys. Alloys combining these metals,
Alternatively, a so-called engineered plastic such as polyetheretherketone or a composite thereof with a fiber, cloth, or nonwoven fabric, a crystalline resin such as polyester, polyamide, polypropylene, or polyethylene, or a composite thereof with a fiber, cloth, or nonwoven fabric, or polyethylene terephthalate , Polymethacrylate, polystyrene and other amorphous resins having a glass transition point of 80 ° C. or higher, and composites thereof with fibers, cloths and nonwoven fabrics.

The Young's modulus (E ₀ ) of the rigid body is 10 ² to 10 ⁶
MPa, preferably 10 ⁴ to 10 ⁶ MPa.
If the rigidity is too low, it is difficult to prevent dimensional changes of the foamed rubber before and after foaming and vulcanization, or dimensional changes such as shrinkage of the foamed rubber over time, resulting in poor dimensional stability, while the rigidity is too high. When the composite of the present invention is deformed, difficulties are involved.

The composite of the present invention refers to a foamed or vulcanized rubber composition before foaming and vulcanization, which is a foamed rubber before foaming and vulcanizing, in order to prevent a dimensional change in an arbitrary direction due to a dimensional change due to an increase in volume accompanying foaming. A composite composed of a foamed rubber and a rigid body, which is restrained and / or bonded with a rigid body and then foamed and vulcanized so that the rubber compound before vulcanization does not change its dimensions in any direction.

The composite of the present invention can be produced, for example, as follows. That is, the rubber compound before foaming and vulcanization has a Young's modulus (E ₀ ) at 23 ° C. of 10 ² to 10 ^6.
The rigid body of MPa is contacted and integrated, and the rubber compound is foamed and vulcanized by heat or the like. At this time, it is preferable that the dimensions of the foamed rubber do not change due to the restraining force of the rigid body. For example, irregularities are formed on the surface of the rigid body to generate an anchor effect, and the contact surface between the foamed rubber and the rigid body does not shift. Or by inserting a plate-shaped rigid body with holes into the rubber compound, and by the binding force generated by the rubber compound entering the holes of the rigid body, before and after foaming and vulcanization of the rubber compound It is effective to restrict the dimensional change at the time. If the rigid body is a metal, by adding a metal acrylate compound to the rubber compound as described above,
Increasing the adhesive strength between the rigid body and the foamed rubber is also effective for restraining the foamed rubber. By such a rigid body restraint, it is possible to prevent a dimensional change before and after foaming and vulcanization of the foamed rubber, and a dimensional change such as shrinkage of the foamed rubber over time.

As described above, the composite of the present invention can use foamed rubber having a cell diameter in a specific range to prevent surface roughness while reducing weight and to maintain appearance and properties comparable to solid rubber. Further, by combining the foamed rubber with a rigid body, the dimensional change of the product can be suppressed to a minimum, that is, the weight reduction and the characteristics expected as a solid rubber can be achieved at the same time. The composite of the present invention having such features can be widely applied to the field of using a rubber and a rigid body such as a metal such as a sealing member such as a door and a trunk of an automobile, a building material, and other industrial articles.

[0029]

The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. Example 1 Ethylene-propylene-non-conjugated diene copolymer rubber (60 parts by weight of Esprene 512F, Esprene 505 4
0 parts by weight Sumitomo Chemical Co., Ltd.) 100 parts by weight of carbon black (Seast G116 manufactured by Tokai Carbon Co., Ltd.) 12
0 parts by weight, 30 parts by weight of calcium carbonate, 75 parts by weight of process oil (PS430 manufactured by Idemitsu Kosan Co., Ltd.), 5 parts by weight of zinc oxide and 2 parts by weight of stearic acid were put into a BR type Banbury mixer set at 70 ° C. Kneaded for minutes. The obtained rubber compound is wound around an open roll of 10 inches, and zinc dibutyldithiocarbamate is used.
2.0 parts by weight, tetramethylthiuram disulfide
0.5 parts by weight, tellurium diethyldithiocarbamate
0.5 parts by weight, 1.5 parts by weight of mercaptobenzothiazole, 7 parts by weight of an antifoaming agent (Vesta PP manufactured by Inoue Lime Co., Ltd.),
1.5 parts by weight of sulfur and azodicarbonamide 10
Parts by weight were added and mixed. As shown in FIG. 1, the rubber compound before foaming and vulcanization was an iron plate (SS41, Young's modulus (E 41)) having a thickness of 0.5 mm, a width of 15 mm, and a length of 150 mm. ₀ ) is 2 × 10 ⁵ MPa)
And press molding so that the outer shape of the rubber compound into which the iron plate is inserted is 2 mm in thickness, 20 mm in width, and 150 mm in length, and then heated and foamed for 4 minutes in a hot air heating furnace set at 185 ° C.・ Vulcanized. A physical test of the obtained foamed rubber was performed according to JIS-K6250 (1998). In addition, the dimensional change rate in the longitudinal direction of the rubber compound into which the iron plate was inserted after foaming and vulcanization was measured.
The results are shown in Table 1.

Comparative Example 1 As Comparative Example 1, a rubber compound before foaming and vulcanization was prepared by the same compounding agent and the same mixing method as in Example 1, and the rubber compound before foaming and vulcanization was cut into a ribbon shape. 45mmΦ made by Nakata Zoki
Introduced to vent type extruder, thickness 2mm, width 20m
m, extruded into a 150 mm long plate,
The mixture was foamed and vulcanized by heating in a hot air heating furnace set at 5 ° C. for 4 minutes. The physical test of the obtained foamed rubber is based on JIS-K625.
0 (1998). Further, the dimensional change rate in the longitudinal direction of the rubber compound extruded into a plate shape after foaming and vulcanization was also measured. The results are shown in Table 1.

[0031]

[Table 1] (1) The average bubble diameter was obtained by taking a 55-times enlarged photograph with an electron microscope, measuring the diameter and number of bubbles observed on the photograph, and arithmetically averaging them. (2) Spring hardness test Durometer type A (JIS-K-6253-1997) Hardness measured with a hardness tester (3) Foaming after foaming and vulcanization of rubber compound before foaming and vulcanization The dimensional change rate in the rubber length direction (150 mm direction) was measured.

[0032]

As described above, according to the present invention, there is provided a composite comprising a foamed rubber and a rigid body, which has extremely fine bubbles, can be reduced in weight, and has excellent surface smoothness and physical properties. A composite comprising a foamed rubber and a rigid body, which maintains dimensional stability while utilizing the properties of the foamed rubber, can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing the appearance of an example of a composite of the present invention.

[Explanation of symbols]

 1 foamed rubber (rubber compound) 2 rigid body

Continued on the front page F-term (reference) 3D024 AA01 AA11 AA16 AB01 AB57 4F074 AA06A AA09A AA12A AA13A AA14A AA23A AA25A AA38A AA48A AA90A BA12 BA13 BA16 BB01 BB05 CA49 CC04Y DA02 DA08 DA04 A08 AK08 BA02 DD23A DJ01A GB36 JA13A JK07B JK12A JL01 JL03 JL04 YY00A YY00B

Claims (2)

[Claims] An average bubble diameter is 1 to 150 μm, and a spring-type hardness test durometer type A (JIS)
-K-6253-1997) The hardness measured by a hardness meter is 30 to 90, and the density is 0.7 to 1.1 kg / L.
And a Young's modulus (E ₀ ) at 23 ° C. of 1
A composite made of a rigid body having a pressure of 0 ² to 10 ⁶ MPa. 2. The foamed rubber is ethylene-α-olefin-
The composite according to claim 1, comprising a non-conjugated diene copolymer rubber.