JP4861691B2 - Rubber composition for infusion sponge and sponge rubber product - Google Patents

Description

  The present invention relates to a high fluidity rubber composition and uses thereof. More specifically, it is possible to provide a molded article having excellent vulcanized physical properties such as heat resistance, weather resistance, ozone resistance, and tear strength, and in addition, precision in injection molding such as transfer molding and injection molding and mold molding. The present invention relates to a high-fluidity rubber composition excellent in moldability and productivity, and a sponge rubber product having good mechanical strength obtained by vulcanizing and foaming a rubber composition.

  Conventionally, ethylene / α-olefin copolymers or ethylene / α-olefin / nonconjugated diene copolymers using ethylidene norbornene as a nonconjugated diene have no unsaturated bond in the main chain. Compared to the above, it is superior in weather resistance, heat resistance and ozone resistance, and is used in rubber products such as automobile industrial parts, industrial rubber products, electrical insulation materials, civil engineering materials, rubberized fabrics and the like. In recent years, with the improvement in performance and functionality of each component, the shape has become more complex and complex, and in transfer molding, injection molding, and mold molding, more excellent flow from the viewpoint of precision moldability and productivity. There is a need for rubber materials having properties.

  When an ethylene / α-olefin / non-conjugated diene copolymer is used as a rubber material, a low molecular weight copolymer is used in order to obtain good processability, that is, resin fluidity during molding. It is.

  However, when a low molecular weight ethylene / α-olefin / diene copolymer is used, there arises a problem that the physical properties, particularly the strength, of the obtained molded product are accompanied.

On the other hand, the present applicants are a composition comprising a specific medium molecular weight ethylene / α-olefin / polyene copolymer and a specific low molecular weight ethylene / α-olefin copolymer or a specific low molecular weight polymer. (Refer to Patent Document 1). However, there is room for improvement in terms of the overall balance of the mechanical properties of the molded body, particularly tensile elongation, tear strength, compression set resistance when foamed (sponge), and fluidity during molding. There is.
JP-A-8-283479

  An object of the present invention is to provide a molded article having excellent vulcanized physical properties such as tensile elongation and tear strength, heat resistance, weather resistance, ozone resistance, and excellent compression set resistance, and transfer. Providing high-fluidity rubber compositions with excellent precision moldability and productivity in injection molding such as molding and injection molding, and sponge rubber products obtained by vulcanizing and foaming the rubber composition There is to do.

  The rubber composition of the present invention is provided by the items described in [1] to [4] below, and the sponge rubber product is provided by the items described in [5] and [6] below.

[1] (A) below (a1) from (a4) and ethylene-propylene-5-ethylidene-2-norbornene copolymer 5 0-8 0 parts by weight satisfying;
(A1) the content of units derived from ethylene is 50 to 90 mol%,
(A2) the content of units derived from non-conjugated polyene is 0.1 to 5 mol%,
(A3) B value represented by the following formula (I) is 1.05 or less,
B value = ([EX] +2 [Y]) / (2 × [E] × ([X] + [Y])) (I)
(Here, [E], [X] and [Y] are the mole fraction of ethylene, propylene and 5-ethylidene-2-norbornene , respectively, and [EX] is the ethylene- propylene dyad chain fraction.)
(A4) The intrinsic viscosity [η] measured with a 135 ° C. decalin solution is 0.1 dl / g or more and less than 2.0 dl / g.
(B) the following (b1) from (b3) and ethylene-propylene-5-ethylidene-2-norbornene copolymer 20-5 0 parts by weight satisfying;
(B1) the content of units derived from ethylene is 50 to 90 mol%,
(B2) the content of units derived from 5-ethylidene-2-norbornene is 0.1 to 5 mol%,
(B3) Intrinsic viscosity [η] measured with a 135 ° C. decalin solution is 2.0 or more and 5.0 dl / g or less,
For a total of 100 parts by weight of (A) and (B) above,
(C) 0.1-15 parts by weight of vulcanizing agent;
(D) A rubber composition comprising 0.1 to 15 parts by weight of a foaming agent.

[2] The rubber composition according to [1], wherein the (B) ethylene / propylene / 5-ethylidene-2-norbornene copolymer satisfies the following (b4):
(B4) B value represented by the following formula (I) is 1.05 or less B value = ([EX] +2 [Y]) / (2 × [E] × ([X] + [Y] )) (I)
(Here, [E], [X], [Y], and [EX] are the same as described above.)
[3] (A) Ethylene / propylene / 5-ethylidene-2-norbornene copolymer according to [1] or [2], and (B) ethylene / propylene / 5-ethylidene-2-norbornene copolymer The rubber composition according to claim 1 or 2, wherein the weight ratio (A) / (B) of the two is 99/1 to 50/50.

  [4] The rubber composition as described in any one of [1] to [3] above, which is for injection molding or molding.

  [5] A sponge rubber product obtained by vulcanizing and foaming the rubber composition according to any one of [1] to [4].

  [6] The sponge rubber product according to the above [5], wherein the sponge rubber product is a corner connecting part of a weather strip for automobiles.

  According to the present invention, since the specific (A) ethylene / α-olefin / polyene copolymer and the specific (B) ethylene / α-olefin copolymer are contained in a specific ratio, heat resistance and weather resistance are included. High fluidity rubber composition with excellent vulcanization properties such as heat resistance, ozone resistance, and tear strength, and excellent precision moldability and productivity in injection molding and mold molding such as transfer molding and injection molding A thing is obtained. Further, by vulcanizing and foaming the rubber composition, a sponge rubber product having the above vulcanized physical properties can be obtained.

[(A) component]
The component (A) in the present invention is a copolymer of ethylene, an α-olefin having 3 to 20 carbon atoms, and a non-conjugated polyene, and satisfies the conditions (a1) to (a4). .

(A) having 3 to 20 carbon atoms in component α- olefin is up propylene.

The non-conjugated polyene in the component (A) is 5-ethylidene-2-norbornene .

Non- conjugated polyenes can be used singly or in combination of two or more.

  The conditions (a1) to (a4) in the component (A) are as follows. By using the component (A) that satisfies such conditions and the specific component (B) described in detail later, The excellent effect of the present invention will be obtained.

(A1) Content of ethylene units:
The content of units derived from ethylene as component (A) is 50 to 90 mol%.

(A2) Content of non-conjugated polyene unit:
The content of units derived from the non-conjugated polyene of component (A) is 0.1 to 5 mol%.

(A3) B value:
In the component (A), the B value represented by the following formula (I) is 1.05 or less.
B value = ([EX] +2 [Y]) / (2 × [E] × ([X] + [Y])) (I)
(Here, [E], [X], and [Y] are ethylene, an α-olefin having 3 to 20 carbon atoms, and a mole fraction of non-conjugated polyene, and [EX] is ethylene to carbon number 3 to 20) The α-olefin dyad chain fraction is shown.)
This B value is an index indicating the randomness of the copolymerization monomer chain distribution.

The above [E], [X], [Y], [EX] measure the ¹³ C-NMR spectrum. C. Randall (Macromolecules, 15, 353 (1982)), J. Ray (Macriolemolecules, 10, 773 (1977), etc. In this report, a copolymer composed of ethylene-propylene is used, The dyads of carbon atoms (methylene groups) in the chain are determined from ¹³ C-NMR spectra, and the randomness and blockiness that are copolymerization forms of the copolymer are discussed from the sequence of the copolymer.

  However, in the above formula (I), the dyad mole fraction of α-olefin and non-conjugated polyene and the dyad mole fraction of non-conjugated polyenes among the dyads obtained between the three types of monomers are both low. This is not considered in the present invention. Further, the dyad mole fraction of ethylene and non-conjugated polyene was assumed to be twice that of the non-conjugated polyene.

  For the non-conjugated polyene copolymer used for the component (A), the molar fraction is separately calculated using the absorption intensity based on the specific carbon of the polyene, and the above assumption is made to determine the dyad mole of ethylene and the non-conjugated polyene. The fraction was calculated. Other chain assignments by methylene carbon were based on the above document.

  Hereinafter, a non-conjugated cyclic polyene copolymer obtained from ethylene, propylene, and 5-ethylidene-2-norbornene (ENB), which are the copolymers of the present invention, is taken as an example, and the B value was obtained as an application. The method will be shown specifically.

First, the integrated value of the absorption intensity of the following nine NMR methylene carbons was determined.
(1) αβ, (2) αγ + αδ, (3) βγ, (4) βδ, (5) γδ, (6) δδ, (7) 3E, (8) 3Z, (9) αα + 1Z + 5E + 5Z + 6E + 6Z
Here, the symbols consisting of numbers and letters in (7) to (9) are carbons derived from ENB, the numbers indicate positions in the following formula, and the letters are E for E and Z for Z respectively. Represents something. The Greek letters indicate the position of the methylene carbon atom between the carbon atoms on the main chain to which the shortest two methyl groups are bonded, and the carbon atom next to the carbon atom to which the methyl group is bonded is defined as α. And For example, if a carbon atom on the main chain is next to the carbon atom to which one methyl group is bonded and is the third from the carbon atom to which the other methyl group is bonded, the carbon atom is αγ It becomes.

  When actually obtaining the integral value, (2) is the sum of multiple peaks around 37-39 ppm, (6) is the sum of the multiple peaks near 29-31 ppm, and the numerical value excluding γγ and γδ peaks. Adopted the sum of multiple peaks around 44 to 48 ppm.

Αα was calculated as follows. The peak was identified by the above-mentioned document: αα = αα + 1Z + 5E + 5Z + 6E + 6Z-2 × 3E-3 × 3Z
= (9) -2 * (7) -3 * (8)
Next, 6 types of dyads obtained between the 3 types of monomers were calculated from the obtained integral values as follows. In addition, NN (ENB-ENB chain) and NP (ENB-propylene chain) of dyad derived from ENB having a small amount of composition were set to 0. As the dyad for NE, a value corresponding to the molar fraction calculated from the absorption intensity assigned to the carbon atoms on the ENB ring was doubled and used.

PP (propylene-propylene chain) = αα + αβ / 4
PE (propylene-ethylene chain) = αγ + αδ + αβ / 2
EE (ethylene-ethylene chain) = (βδ + δδ) / 2 + (γδ + βγ) / 4
NE (ENB-ethylene chain) = (3E + 3Z) × 2
Finally, each mole fraction of the composition was calculated as follows.

[E] (ethylene mole fraction) = (EE + PE / 2) / (PP + PE + EE + 3E + 3Z)
[EX] (Dyad mole fraction of ethylene and α-olefin) = PE / (PP + PE + EE + NE)
[X] (α-olefin molar fraction) = (PP + PE / 2) / (PP + PE + EE + 3E + 3Z)
[Y] (non-conjugated polyene molar fraction) = (3E + 3Z) / (PP + PE + EE + 3E + 3Z)
The B value was calculated by substituting into the above formula (I) using each mole fraction of the composition obtained above.

  In the above formula (I), the larger the B value, the shorter the block chain of α-olefin (propylene) units or non-conjugated cyclic polyene units, and the distribution of α-olefin (propylene) units and non-conjugated cyclic polyene units increases. It shows that it is uniform. Conversely, the smaller the B value, the more uneven the distribution of the non-conjugated cyclic polyene copolymer, indicating that the block chain becomes longer. In the copolymer, there is a close relationship between the copolymerization properties such as randomness and block property and the physical properties of the copolymer, and if the randomness increases as the relationship between the copolymerization properties and physical properties of the copolymer, Although the mechanical strength is improved, the fluidity tends to decrease due to the decrease in slip between the molecular chains. If the blockiness increases, the reverse trend will occur.

  In the present invention, it is one of the important structures that the balance between the two values can be obtained when the B value is 1.05 or less.

  In the production of the copolymer, the B value is controlled by controlling the polymerization conditions such as the type of catalyst, catalyst amount, polymerization pressure, polymerization temperature, polymerization time, monomer supply concentration, monomer supply rate, and monomer supply sequence. It can be implemented. In particular, the type of catalyst is effective in control, and in the present invention, it is preferable to control using a so-called metallocene catalyst.

(A4) Intrinsic viscosity:
Intrinsic viscosity [η] measured with a solution of component (A) in decalin at 135 ° C. is 0.1 dl / g or more and less than 2.0 dl / g. By blending such a component (A) with a component (B) having a higher intrinsic viscosity than this, the excellent effects of the present invention can be obtained.

  In the production of the component (A), the polymerization catalyst and the polymerization conditions are not particularly limited, but an appropriate polymerization catalyst and polymerization conditions are selected by controlling so as to satisfy the conditions of the component (A). As the polymerization catalyst, various conventionally known catalysts such as a Ziegler-Natta catalyst, a metallocene catalyst, an imine catalyst, and a phenoxyimine catalyst can be used, and a metallocene catalyst is preferably used as described above. As for the polymerization method, for example, conventionally known polymerization methods such as solution polymerization, slurry polymerization, and bulk polymerization can be employed. Specifically, for example, each monomer is continuously supplied into the reactor, the copolymerization reaction is allowed to proceed at a predetermined temperature in the presence of a catalyst, and the obtained copolymer rubber is separated and dried. For the purpose of adjusting P, melt kneading may be performed with an extruder.

[Component (B)]
The component (B) in the present invention is a copolymer of ethylene, an α-olefin having 3 to 20 carbon atoms, and a non-conjugated polyene, and satisfies the conditions (b1) to (b3). . The α-olefin having 3 to 20 carbon atoms in the component (B) is propylene, and the non- conjugated polyene is 5-ethylidene-2-norbornene. Regarding these preferable specific examples and the production method thereof, This is the same as the example given above in the description of the component (A).

  The conditions (b1) to (b3) in the component (B) are as follows, and the excellent effect of the present invention can be obtained by using the component (B) that satisfies such conditions together with the component (A). Will be.

(B1) Ethylene unit content:
The content of the unit derived from ethylene as the component (B) is 50 to 90 mol%.

(B2) Content of non-conjugated polyene unit:
The content of units derived from the non-conjugated polyene of component (B) is 0.1 to 5 mol%.

(B3) Intrinsic viscosity:
(B) The intrinsic viscosity [η] measured with a 135 ° C. decalin solution is 2.0 or more and 5.0 dl / g or less. By blending such a component (B) having an intrinsic viscosity with the component (A) having a low intrinsic viscosity and a specific B value as described above, the excellent effects of the present invention can be obtained.

  Moreover, also about (B) component, it is preferable that B value represented by Formula (I) is 1.05 or less similarly to (A) component (condition b4). Details of the B value are as described above.

[Component (C)]
The component (C) in the present invention is a vulcanizing agent.
As this vulcanizing agent, for example, various conventionally known ones such as sulfur, sulfur compounds and organic peroxides can be used. In particular, it is preferable to use sulfur. Specific examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur, insoluble sulfur and the like. Specific examples of the sulfur-based compound include sulfur chloride, sulfur dichloride, and polymer polysulfide. In addition, when using sulfur or a sulfur type compound as a vulcanizing agent, it is preferable to use a vulcanization accelerator together. The amount of the vulcanizing agent is 0.1 to 15 parts by weight with respect to 100 parts by weight in total of the above (A) and (B).

[(D) component]
(D) component in this invention is a foaming agent.
As this foaming agent, various conventionally known ones such as an inorganic foaming agent, a nitroso compound, an azo compound, a sulfonyl hydrazide compound, and an azide compound can be used. In particular, it is preferable to use an azo compound such as azodicarbonamide. Moreover, you may use a foaming adjuvant with a foaming agent as needed. The amount of the foaming agent is 0.1 to 15 parts by weight with respect to 100 parts by weight as a total of the above (A) and (B).

[Preparation of rubber composition]
The rubber composition of the present invention, above-described (A) to contain ~ (D) component is a composition comprising, 5 0-8 0 parts by weight of component (A), component (B) 20 ~ 5 0 parts by weight, 0.1 to 15 parts by weight of component (C), can be prepared by a 0.1 to 15 parts by weight, blended component (D).

  Components other than these are not particularly limited, and various conventionally known additive components such as rubber reinforcing agents, fillers, softeners, anti-aging agents, processing aids, flame retardants and the like do not impair the purpose of the present invention. Can be blended within.

  The rubber composition of the present invention kneads the copolymer rubber and other components at a predetermined temperature using a conventionally known kneader such as a Banbury mixer, kneader, roll, uniaxial or biaxial extruder. Can be prepared. Specifically, for example, the component (A) and the component (B), and other components such as a filler and a softening agent, if necessary, are kneaded at a predetermined temperature by a Banbury mixer. A desired rubber composition can be obtained by additionally mixing the components (C) and (D) and other components as required using rolls and kneading at a predetermined temperature.

  The rubber composition of the present invention can be molded and vulcanized by various conventionally known molding methods, but is very useful as a molding material for injection molding or molding, such as transfer molding or injection molding. .

[Sponge rubber products]
The sponge rubber product of the present invention is obtained by vulcanizing and foaming the rubber composition of the present invention described above. This sponge rubber product is manufactured by, for example, preparing the above-mentioned unvulcanized unfoamed rubber composition once, then molding the rubber composition into an intended shape, and then foaming and vulcanizing. Can do.

  Since this sponge rubber product has excellent characteristics, it can be used in various applications such as automotive parts such as weather strips, door glass run channels, trunk seals, industrial rubber products such as rubber rolls, electrical insulation materials, and civil engineering materials. Can be used. In particular, it is very suitable as a corner part connecting part of an automobile weather strip.

  The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to the following examples.

[Synthesis Examples 1, 2 and 5] Synthesis of Copolymers 1, 2 and 5 Using a 15 L stainless steel polymerization vessel equipped with stirring blades, a terpolymerization reaction of ethylene, propylene and ENB was continuously carried out. It was. Hexane was continuously fed from the top of the polymerization vessel as a polymerization solvent at a rate of 5 L / hour. On the other hand, the polymerization solution was continuously withdrawn from the lower part of the polymerization vessel so that the polymerization solution in the polymerization vessel was always 5 L. Vanadium oxychloride and ethylaluminum sesquichloride were used as catalysts. The former was supplied so that the vanadium concentration in the polymerization vessel was 0.3 mmol / L, and the latter was supplied so that the aluminum concentration was 3 mmol / L. The polymerization temperature was adjusted to 30 ° C. according to the brine temperature in the jacket of the polymerization vessel. The resulting polymerization solution was subjected to a standard deashing operation, and then a resin was obtained by steam stripping or flash drying. Table 1 shows the raw material supply conditions and the polymer properties obtained.

[Synthesis Examples 3 and 4] Synthesis of Copolymers 3 and 4 Polymerization was carried out by a continuous method using a 300 L reactor with a stirrer made of SUS at a temperature of 80 ° C and a liquid level of 100 L. (T-Butylamido) dimethyl (tetramethyl-η ⁵ -cyclopentadienyl) silane titanium dichloride as the main catalyst, (C ₆ H ₅ ) ₃ CB (C ₆ F ₅ ) ₄ as the cocatalyst and triisobutyl as the organoaluminum compound Aluminum (hereinafter referred to as TIBA) was used. A resin was obtained from the resulting polymerization solution by steam stripping or flash drying. Table 2 shows the raw material supply conditions and the obtained polymer physical properties.

[Production Example] Production and Evaluation Test Method of Vulcanized Foam Molded Body (1) Kneading Each copolymer, zinc white, stearic acid, carbon black and plasticizer are mixed in a 1.7 liter BR type Banbury mixer for 5 minutes. After kneading, the kneaded material was collected with an 8-inch roll and allowed to cool.

(2) Mooney viscosity (ML (1 + 4))
The compound Mooney viscosity of this kneaded product was measured according to JIS-K6300 (2001) using an L-shaped rotor at measurement temperatures of 100 ° C. and 50 ° C.

(3) Vulcanization and foaming A predetermined amount of the above composition was weighed, and a vulcanizing agent, a vulcanization accelerator, a foaming agent and a foaming aid were added by an 8-inch roll kept at 50 ° C., and kneaded for 8 minutes. . A transfer molding machine is used for vulcanization, and the kneaded material obtained as described above is poured into a tubular mold 1 as shown in FIG. 1 in 10 seconds, and the mold temperature is 180 ° C. for 3.5 minutes. A tubular sponge was obtained by sulfur foaming.

(4) Specific gravity A 20 mm × 20 mm test piece was punched from the top of the vulcanized tube-like sponge, and the surface was wiped off with alcohol. This specimen was attached to an automatic hydrometer [manufactured by Toyo Seiki Seisakusho: M-1 type] in an atmosphere of 25 ° C., and the specific gravity was measured from the difference in mass between air and pure water.

(5) Water absorption rate A test piece of 20 mm × 20 mm was punched out from the upper part of the vulcanized tubular sponge, and the weight of the test piece was measured. Next, 100 mm or more of water is put into a desiccator with a suction port from the bottom, and a test piece is put therein. The test piece was submerged under the water surface with a wire mesh so as not to float. In this state, the inside of the desiccator is depressurized with a vacuum pump and held at 635 mmHg. Remove the vacuum after 3 minutes and hold for another 3 minutes. After removing the test piece and wiping off the water droplets on the surface of the test piece, the weight was measured, and the water absorption was calculated by the following formula.
Water absorption (%) = [(W ₂ −W ₁ ) / W ₁ ] × 100
W ₁ : Weight of specimen before immersion (g)
W ₂ : Test piece weight after immersion (g)

(6) Tensile test (M100, M200, TB, and EB)
The upper part of the vulcanized tubular sponge was punched in the length direction with a No. 3 type dumbbell described in JIS K 6301 (1989) to obtain a test piece. Using this test piece, in accordance with the method defined in paragraph 3 of JIS K 6301, a tensile test was performed under the conditions of a measurement temperature of 25 ° C. and a tensile speed of 500 mm / min, and stress at 100% elongation (M100), 200 The stress at% elongation (M200), the tensile stress at break (TB), and the tensile elongation at break (EB) were measured.

(7) Tear test (TR-sponge)
A strip-shaped test piece having a length of 120 mm and a width of 25 mm is punched in the length direction from the vulcanized tube-like sponge upper portion, along the longitudinal center line (line direction) from one end to one third of the length, A cut was made with a single blade. After measuring the thickness of the test piece, the cut portion is attached to a tensile tester so that the distance between chucks is 40 mm. Subsequently, the test piece was pulled at a measurement temperature of 25 ° C. and a tensile speed of 200 mm / min until the specimen was cut, and the tear strength (TR-sponge) was measured.

(8) Compression set test (Cs)
The vulcanized tube-like sponge is cut into a length of 30 mm and attached to a compression device (device described in JIS K 6301). The test piece was compressed so that its height was half that before the load was applied, and the mold was heat treated in a gear oven at 70 ° C. for 200 hours. Subsequently, the heat-treated test piece was taken out from the compression apparatus, allowed to cool for 30 minutes, the height of the test piece was measured, and the compression set (Cs) was calculated by the following formula.
Compression set Cs (%) = [(t ₀ −t ₁ ) / (t ₀ −t ₂ )] × 100
t ₀ : Height of the test piece before test t ₁ : Heat treatment of the test piece, taking out from the compression apparatus, and letting it cool for 30 minutes t ₂ : Mounting the test piece to the measurement die Height in state

(9) Fluidity Evaluation Test Using the above transfer molding machine, 10 g or 13 g of the compounded rubber was injected into the mold 2 shown in FIG. 2 in 10 seconds, and vulcanized at a mold temperature of 180 ° C. for 3.5 minutes. The vulcanizate was taken out of the mold, and the length of the free-foamed molded product (L (mm) in FIG. 2) was measured.

[Example 1]
20 parts by weight of the copolymer 2 shown in Table 1, 80 parts by weight of the copolymer 3 shown in Table 2, 10 parts by weight of activated zinc white [META Z102, manufactured by Inoue Lime Industry Co., Ltd.], 2 parts by weight of stearic acid, , SRF carbon black [trade name Asahi # 50, manufactured by Asahi Carbon Co., Ltd.] 75 parts by weight, paraffinic process oil [trade name Diana Process PW-380, made by Idemitsu Kosan Co., Ltd.] 80 parts by weight, mineral black [history Blue fine powder Keystone Filler & Mfg. 20 parts by weight were kneaded with a Banbury mixer. Furthermore, 2-mercaptobenzothiazole [trade name Sunseller M, manufactured by Sanshin Chemical Industry Co., Ltd.] 0.5 part by weight, zinc di-n-butyldithiocarbamate (trade name Sunseller BZ) with respect to 222 parts by weight of this blend. 1.5 parts by weight, manufactured by Sanshin Chemical Industry Co., Ltd., tetramethylthiuram disulfide [trade name Sunseller TT, manufactured by Sanshin Chemical Industry Co., Ltd.] 0.5 parts by weight, tetraethylthiuram disulfide [trade name Sunseller TET, Sanshin Chemical Industry Co., Ltd.] 0.5 parts by weight, sulfur 0.8 parts by weight, foaming agent azodicarbonamide [trade name Binihol AC # 3, manufactured by Eiwa Kasei Co., Ltd.] 7 parts by weight, foaming aid 2 parts by weight of urea [trade name Cell Paste 101, manufactured by Eiwa Kasei Co., Ltd.] was added by an 8-inch roll having a surface temperature of 50 ° C. and kneaded to obtain a compounded rubber.

  This compounded rubber was vulcanized and foamed by the method described above to obtain a vulcanized foamed rubber. About the obtained vulcanized foamed rubber, specific gravity, water absorption, tensile breaking stress (TB), tensile breaking elongation (EB), tear strength (TR-sponge) and compression set (Cs) are determined by the methods described above. It was. Moreover, the fluidity test was conducted on the compounded rubber before vulcanization foaming by the method described above. Table 3 shows the adjustment results in Example 1, and Table 4 shows the evaluation results.

[Comparative Example 1]
A compounded rubber and a vulcanized foam rubber were prepared and evaluated in the same manner as in Example 1 except that the copolymer 1 was used instead of the copolymer 3 in Example 1. The adjustment results are shown in Table 3, and the evaluation results are shown in Table 4, respectively.

[Examples 2 and 3 and Comparative Examples 2 and 3]
In place of the copolymers 2 and 3 in Example 1, a predetermined amount of the copolymer shown in Table 3 was used, and various compounding agents shown in Table 3 were used in the same manner as in Example 1 to compound rubber and vulcanization. Foam rubber was prepared and evaluated. The adjustment results are shown in Table 3, and the evaluation results are shown in Table 4, respectively.

[Comparison of results between Example and Comparative Example]
From Table 4, the following can be understood. Example 1 using the copolymer 3 polymerized with the metallocene catalyst, compared with Comparative Example 1 using the copolymer 1 polymerized with the vanadium catalyst, is fluid in spite of the high Mooney viscosity (ML) of the compound. The property (L) is excellent. In addition, the tensile elongation at break, tensile strength at break, and tear strength are excellent. Further, from the comparison of Examples 1 and 2 with respect to Comparative Example 2, the difference due to the above comparison is more remarkable. Furthermore, compared with the comparative example 3 corresponding to the said Unexamined-Japanese-Patent No. 8-8283479 of the said patent document 1, especially fluidity | liquidity and tear strength are excellent.

  The rubber composition of the present invention can be widely used as a raw material for rubber products, and can be suitably used for sponge rubber products obtained therefrom. Specifically, weather strips, door glass run channels, trunk seals, especially automobile interior parts such as corner connection parts and end parts, electrical parts having complicated shapes, various seal parts, heat insulating materials, cushion materials, sheet It can use suitably for uses, such as a ring material.

FIG. 1 is a view showing a vulcanization / foaming mold used in Examples, etc. FIG. 1 (a) is a front view of the mold, and FIG. 1 (b) is a view of the mold. It is a side view. FIG. 2 is a diagram showing a vulcanization / foaming mold used for preparing a test piece to be subjected to a fluidity evaluation test. FIG. 2 (a) is a plan view of the mold, and FIG. b) is a front view of this mold.

Explanation of symbols

1; Mold for vulcanization foam molding 2; Mold for vulcanization foam molding L: Length of molded product with free foaming

Claims (6)

(A) below (a1) from (a4) and ethylene-propylene-5-ethylidene-2-norbornene copolymer 5 0-8 0 parts by weight satisfying;
(A1) the content of units derived from ethylene is 50 to 90 mol%,
(A2) the content of units derived from 5-ethylidene-2-norbornene is 0.1 to 5 mol%,
(A3) B value represented by the following formula (I) is 1.05 or less,
B value = ([EX] +2 [Y]) / (2 × [E] × ([X] + [Y])) (I)
(Here, [E], [X] and [Y] are the mole fraction of ethylene, propylene and 5-ethylidene-2-norbornene , respectively, and [EX] is the ethylene- propylene dyad chain fraction.)
(A4) The intrinsic viscosity [η] measured with a solution in 135 ° C. decalin is 0.1 dl / g or more and less than 2.0 dl / g.
(B) the following (b1) from (b3) and ethylene-propylene-5-ethylidene-2-norbornene copolymer 20-5 0 parts by weight satisfying;
(B1) the content of units derived from ethylene is 50 to 90 mol%,
(B2) the content of units derived from 5-ethylidene-2-norbornene is 0.1 to 5 mol%,
(B3) Intrinsic viscosity [η] measured with a 135 ° C. decalin solution is 2.0 or more and 5.0 dl / g or less,
For a total of 100 parts by weight of (A) and (B) above,
(C) 0.1-15 parts by weight of vulcanizing agent;
(D) A rubber composition comprising 0.1 to 15 parts by weight of a foaming agent. The rubber composition according to claim 1, wherein the (B) ethylene / propylene / 5-ethylidene-2-norbornene copolymer according to claim 1 satisfies the following (b4).
(B4) B value represented by the following formula (I) is 1.05 or less B value = ([EX] +2 [Y]) / (2 × [E] × ([X] + [Y] )) (I)
(Here, [E], [X], [Y], and [EX] are the same as described above.) The (A) ethylene / propylene / 5-ethylidene-2-norbornene copolymer according to claim 1 or 2, and also the (B) ethylene / propylene / 5-ethylidene-2-norbornene copolymer, The rubber composition according to claim 1 or 2, wherein the weight ratio (A) / (B) is 99/1 to 50/50.   The rubber composition according to any one of claims 1 to 3, wherein the rubber composition is for injection molding or molding.   A sponge rubber product obtained by vulcanizing and foaming the rubber composition according to claim 1.   6. The sponge rubber product according to claim 5, wherein the sponge rubber product is a corner part connecting part of a weather strip for automobiles.

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