JP4698342B2 - Rubber composition and conveyor belt using the rubber composition - Google Patents

Description

  The present invention relates to a rubber composition, and more particularly to a rubber composition in which an ethylene / propylene copolymer rubber is used as a base, and a conveyance belt using the rubber composition.

Conventionally, rubber compositions are generally superior in mechanical strength such as crack resistance and wear resistance compared to plastics, etc., and are generally strong, so they are used for transporting ores and earth and sand. It is used for the belt body part.
For example, this conveyor belt is used for conveying high-temperature conveyed objects such as sintered ores and clinker in industrial fields such as steel and cement. Such a conveyor belt used for a high-temperature conveyed product is called a heat-resistant belt or the like, and is usually used for conveying a conveyed product at 150 ° C. or higher. This heat-resistant belt is required to have an excellent heat-resistant life in addition to mechanical strength such as wear resistance and crack resistance. Regarding such thermal and mechanical properties, a rubber composition obtained by crosslinking an ethylene / α-olefin copolymer rubber or the like with an organic peroxide-based crosslinking agent should be better than other rubber compositions. Is conventionally known.
In an example of Patent Document 1, a rubber composition containing an ethylene / propylene copolymer containing a third component in addition to ethylene and propylene and a relatively fine carbon black called HAF is used as a heat resistant belt. The use is described.
However, such a conventional rubber composition has a problem that the thermal and mechanical properties are not sufficiently improved, and it is difficult to sufficiently satisfy the properties required for the heat-resistant belt.

In this regard, Patent Document 2 describes that a base rubber containing an ethylene / propylene copolymer and an ethylene / 1-octene copolymer is used for the heat-resistant belt. However, when the rubber described in Patent Document 2 is used, there is a problem that roll processability and molding adhesiveness during rubber kneading are impaired.
Therefore, the rubber composition used for the conventional heat-resistant belt has a problem that it is difficult to improve the thermal and mechanical properties while suppressing the roll processability and molding adhesiveness from being impaired.
Such problems are common not only to rubber compositions used for heat-resistant belts, but also to all rubber compositions that require improved heat and mechanical properties while suppressing the loss of roll processability and molding adhesiveness. To do.

Japanese Patent Laid-Open No. 10-168257 Japanese Patent Laid-Open No. 11-246017

  In view of the above problems, an object of the present invention is to provide a rubber composition capable of improving thermal and mechanical properties while suppressing roll processability and molding adhesiveness from being impaired.

In order to solve the above-mentioned problems, the present inventors have intensively studied the blending of the rubber composition. As a result, the ethylene-propylene copolymer rubber containing a predetermined amount of ethylene norbornene as the third component, A rubber composition containing a predetermined amount of carbon black having a particle size and a predetermined structure has been found to have excellent roll processability and molding adhesiveness, and excellent heat resistance, crack resistance, and wear resistance. It has been completed.
That is, the present invention relates to an ethylene / propylene / ethylene norbornene copolymer in which the proportion of ethylene in the total of ethylene and propylene is 65% by weight or more and 0.1 to 1.0% by weight of ethylene norbornene is contained. rubber, it is used in more than 50% by weight of the total polymer component, 30 to carbon black iodine adsorption 50 to 70 g / kg and DBP oil absorption amount 135~160cm ³ / 100g on 100 parts by weight of the total polymer component A rubber composition comprising 70 parts by weight is provided.
In the present invention, the polymer component is intended to have a number average molecular weight (Mn) of 50,000 or more and a ratio (Mn / Mw) of 2 or more to the weight average molecular weight (Mw). The average molecular weight and the weight average molecular weight can be measured, for example, by dissolving a polymer component in a solvent such as tetrahydrofuran (THF) and using a gel permeation chromatograph (GPC) apparatus with polystyrene as a reference substance.

According to the present invention, an ethylene / propylene / ethylene norbornene copolymer rubber containing 0.1 to 1.0% by weight of ethylene norbornene and 65% by weight or more of ethylene component in the rubber composition is a polymer of the rubber composition. are used in more than 50% by weight of component, moreover, 30-70 parts by weight containing carbon black iodine adsorption 50 to 70 g / kg and DBP oil absorption amount 135~160cm ³ / 100g on 100 parts by weight of the polymer components Therefore, roll processability and molding adhesiveness are not impaired as in the case of using rubber containing ethylene / propylene copolymer and ethylene / 1-octene copolymer. Moreover, according to this invention, a rubber composition can be made excellent in heat resistance, crack resistance, and abrasion resistance. Accordingly, the rubber composition can be made excellent in thermal and mechanical properties while suppressing the roll processability and molding adhesiveness from being impaired.

Hereinafter, a rubber composition used for a belt body of a heat resistant belt will be described as an example of a preferred embodiment of the present invention.
First, the compounding material used for the rubber composition forming the belt body of the heat-resistant belt will be described.

  The rubber composition of this embodiment contains a rubber component, carbon black, a crosslinking agent, and a co-crosslinking agent.

In the rubber component, an ethylene / propylene / ethylene norbornene copolymer rubber is used as a base polymer.
This ethylene / propylene / ethylene norbornene copolymer rubber contains 0.1 to 1.0% by weight of ethylene norbornene as a third component other than the ethylene component and the propylene component. The ethylene component is contained in the ethylene / propylene / ethylene norbornene copolymer rubber in a proportion of 65% by weight or more with respect to the total of ethylene and propylene. Preferably, the weight ratio of ethylene to propylene is , Ethylene: propylene = 80: 20 to 65:35 can be used.
Further, as the polymer component, only such ethylene / propylene / ethylene norbornene copolymer rubber may be used, or other rubbers may be mixed and used. The ethylene / propylene / ethylene norbornene copolymer rubber is of a single type as long as it contains 0.1 to 1.0% by weight of ethylene norbornene and 65% by weight or more of the ethylene component. Not limited to this, a plurality of types of ethylene / propylene / ethylene norbornene copolymer rubbers may be mixed and used.
However, the total amount of the ethylene / propylene / ethylene norbornene copolymer rubber containing 0.1 to 1.0% by weight of ethylene norbornene and 65% by weight or more of the ethylene component is 50% by weight or more of the total polymer components. It is said. When the ethylene / propylene / ethylene norbornene copolymer rubber is less than 50% by weight in the total polymer components, it cannot be excellent in wear resistance and heat resistance.
The ethylene component of the ethylene / propylene / ethylene norbornene copolymer rubber is 65% by weight or more when an ethylene / propylene / ethylene norbornene copolymer rubber having an ethylene component of less than 65% by weight is used. This is because the rubber composition does not have excellent wear resistance and heat resistance. Moreover, since there exists a possibility that a rubber composition may become inferior to workability when an ethylene component exceeds 80 weight%, it is preferable that an ethylene component is 80 weight% or less.
In addition, the ethylene norbornene weight ratio of the ethylene / propylene / ethylene norbornene copolymer rubber is set in such a range, if the ethylene norbornene is less than 0.1% by weight, the wear resistance is not sufficient. If the amount exceeds 1.0% by weight, a rubber composition with improved heat resistance cannot be obtained, and a decrease in wear resistance due to thermal deterioration is caused by a decrease in heat resistance. .

Examples of the rubber other than the ethylene / propylene / ethylene norbornene copolymer rubber include ethylene / propylene copolymer rubbers and ethylene / octene copolymers in which monomers other than ethylene norbornene are copolymerized in addition to ethylene and propylene. Rubber, ethylene-butene copolymer rubber or natural rubber, styrene-butadiene copolymer rubber, chloroprene rubber, hydrogenated nitrile-butadiene rubber, alkylated chlorosulfonated polyethylene, isoprene rubber, epichlorohydrin rubber, butyl rubber, acrylic rubber, etc. Can be used alone or in combination.
Examples of monomers other than ethylene norbornene include non-conjugated diene components such as 1,4-pentadiene, 1,4-hexadiene, 1,5-cyclooctadiene, butene, pentene, heptene, octene, and the like. Can be used.

Further, the carbon black, those of iodine adsorption 50 to 70 g / kg and DBP oil absorption amount 135~160cm ³ / 100g is used. Further, the carbon black content in the rubber composition of the present embodiment is 30 to 70 parts by weight with respect to 100 parts by weight of the polymer component.
The use of carbon black such iodine adsorption and DBP absorption, for example, in place of that of iodine adsorption 50 to 70 g / kg and DBP oil absorption amount 135~160cm ³ / 100g, for example, iodine adsorption amount When using carbon black called HAF or ISAF that is larger than the above range and has a DBP oil absorption value smaller than the above range, the wear resistance and crack resistance of the rubber composition are not sufficiently improved in a well-balanced manner. It is.
Incidentally, if necessary, it is also possible to use a HAF and ISAF, in addition to carbon black iodine adsorption 50 to 70 g / kg and DBP oil absorption amount 135~160cm ³ / 100g within a range not impairing the effects of the present invention . However, the content of carbon black in such a case even iodine adsorption 50 to 70 g / kg and DBP oil absorption amount 135~160cm ³ / 100g is 30 to 70 parts by weight relative to the polymer component 100 parts by weight .
The iodine adsorption amount can be measured by a measurement method defined in JIS K 6217-1, and the DBP oil absorption amount can be measured by a measurement method defined in JIS K 6217-4.

Moreover, as said crosslinking agent, an organic peroxide type crosslinking agent can be used, for example.
Although it does not specifically limit as this organic peroxide type crosslinking agent, For example, di-t-butyl peroxide, di-t-amyl peroxide, t-butyl cumyl peroxide, dicumyl peroxide, 1,4- Di-t-butylperoxyisopropylbenzene, 1,3-di-t-butylperoxyisopropylbenzene, 2,2-di-t-butylperoxybutane, 2,5-dimethyl-2,5-di- ( t-butylperoxy) hexane, 2,5-dimethyl-2,5-di-t-butylperoxy) hexyne-3, n-butyl-4,4-di-t-butylvalerate, 1,1- Di-t-butylperoxycyclohexane, di-t-butylperoxy-3,3,5-trimethylcyclohexane, 2,2-bis (4,4-di-t-butylperoxycyclohexane Xyl) propane and other dialkyl peroxides; t-butyl peroxyacetate, t-butyl peroxyisobutyrate, t-butyl peroxypivalate, t-butyl peroxymaleic acid, t-butyl peroxyneodecano Ate, t-butyl peroxybenzoate, di-t-butyl peroxyphthalate, t-butyl peroxydilaurate, 2,5-dimethyl-2,5-di- (benzoylperoxy) hexane, t-butylperoxyisopropyl Peroxyesters such as carbonate; ketone peroxides such as dicyclohexanone peroxide can be used.

  Examples of the co-crosslinking agent include metal-containing monomers such as methacrylic acid metal salts, polyfunctional monomers such as ethylene glycol dimethacrylate and triallyl cyanurate, sulfur-containing compounds, p-quinonedioxime, p, p′dibenzoylquinonedi. Oxime, N, N ′ metaphenylene bismaleimide and the like can be used.

  If necessary, in addition to the above compounding materials, reinforcing agents, fillers, oils, antioxidants, tackifiers, processing aids, crosslinking aids, vulcanization acceleration aids generally incorporated in rubbers. You may mix | blend an agent, a coloring agent, etc. suitably in the range which does not impair the effect of this invention.

Next, a method for producing a belt body of a heat-resistant belt using such a compounding material will be described.
The belt body of this heat-resistant belt is manufactured by covering a core body in which one or more composites of rubber and canvas are laminated with a cover rubber.
The core body can be manufactured by laminating and integrating a rubber sheet for a core body obtained by forming the compounded material into a sheet shape and cross-linking and a canvas by a general laminating method. For example, the compounded material is kneaded with a Banbury mixer, a kneader mixer, a roll, etc., then formed into a sheet shape, and a core sheet rubber sheet is produced by a method such as crosslinking at 150-170 ° C. for 10-60 minutes. For example, it is made of cotton, human silk, polyvinyl alcohol fiber, aliphatic polyamide fiber such as 6-nylon, 6,6-nylon, aromatic polyamide fiber, polyester fiber, rayon fiber, glass fiber, carbon fiber, etc. The canvas and the core rubber sheet can be manufactured by laminating and integrating using a bonding rubber or the like.

  The cover rubber can be manufactured in the same manner as the core rubber sheet. The cover rubber is covered with the cover rubber by laminating and integrating the cover rubber on the core using an adhesive rubber or the like. Thus, the belt body of the heat-resistant belt can be manufactured.

  In the present embodiment, a rubber composition excellent in heat resistance and crack resistance is required, and in the case where the effect of the present invention can be made more remarkable, especially when used for a conveyor belt, 150 ° C. Although the heat-resistant belt used for conveying the above-mentioned conveyance object was demonstrated to the example, in this invention, the use of a rubber composition is not limited to a heat-resistant belt.

  EXAMPLES Next, although an Example is given and this invention is demonstrated in more detail, this invention is not limited to these.

(Examples 1-3, Comparative Examples 1-5)
The compounding shown in Table 1 is kneaded with a closed kneader to create a rubber compound, and the prepared rubber compound is then press-molded into a sheet under a pressing condition of 160 ° C. × 30 minutes using a hot press. A rubber composition was prepared. Table 2 shows the ratio of ethylene to propylene and the ethylene norbornene content for the polymer components listed in Table 1. Table 3 shows the iodine adsorption amount and DBP oil absorption amount of the carbon black listed in Table 1.

※ 表中の配合剤の各数値は重量部数を示す。また、配合剤の詳細は下記のとおり。
ポリマー１ ：ダウ・ケミカル製（エチレン・フ゜ロヒ゜レン・エチレンノルホ゛ルネン共重合体コ゛ム）、
商品名「ノーデルＩＰ３７２０」
ポリマー２ ：ＪＳＲ製（エチレン・フ゜ロヒ゜レン共重合体コ゛ム）、商品名「Ｔ７９４２」
ポリマー３ ：ダウ・ケミカル製（エチレン・オクテン共重合体コ゛ム）、
商品名「エンゲージ８１００」
ポリマー４ ：ＪＳＲ製（エチレン・フ゜ロヒ゜レン・エチレンノルホ゛ルネン共重合体コ゛ム）、
商品名「ＥＰ４３」
カーホ゛ンフ゛ラック１ ：昭和キャボット製「カーボンＩＰ６００」
カーホ゛ンフ゛ラック２ ：昭和キャボット製「カーボンＨＡＦ−ＨＳ」
カーホ゛ンフ゛ラック３ ：昭和キャボット製「カーボンＩＳＡＦ」
プロセスオイル：日本サン石油製、商品名「サンパー２２８０」
粘着剤 ：ユニロイヤルケミカルカンパニー製、商品名「トライレン６７」
老化防止剤１ ：大内新興化学製、商品名「ノクラックＭＢ」
老化防止剤２ ：大内新興化学製、商品名「ノクラック２２４」
架橋剤 ：ジクミルパーオキサイド
共架橋剤 ：メタクリル酸亜鉛

* Each numerical value of the compounding agent in the table indicates the number of parts by weight. The details of the compounding agent are as follows.
Polymer 1: manufactured by Dow Chemical (Ethylene / Fluoroethylene / Ethylene Norbornene Copolymer Comb),
Product name "Nodel IP3720"
Polymer 2: Product made by JSR (ethylene-propylene copolymer copolymer), trade name “T7942”
Polymer 3: Dow Chemical (ethylene octene copolymer rubber),
Product name "engage 8100"
Polymer 4: manufactured by JSR (ethylene / fluoropropylene / ethylene norbornene copolymer rubber),
Product name “EP43”
Carbon Black 1: "Carbon IP600" manufactured by Showa Cabot
Carbon Black 2: "Carbon HAF-HS" manufactured by Showa Cabot
Carbon Black 3: “Carbon ISAF” manufactured by Showa Cabot
Process oil: Nippon San Oil Co., Ltd., trade name “Samper 2280”
Adhesive: Made by Uniroyal Chemical Company, trade name “Trilen 67”
Anti-aging agent 1: Product name “NOCRACK MB” manufactured by Ouchi Shinsei Chemical
Anti-aging agent 2: manufactured by Ouchi Shinsei Chemical, trade name “NOCRACK 224”
Crosslinking agent: Dicumyl peroxide Co-crosslinking agent: Zinc methacrylate

※ 「−」はエチレンノルボルネンを含有していないことを示す。
※※ エチレン／オクテン重量比

* “-” Indicates that no ethylene norbornene is contained.
** Ethylene / octene weight ratio

(Heat resistance evaluation)
JIS K 6251 No. 3 dumbbell-shaped test pieces were prepared from the 2 mm-thick sheets of each Example and Comparative Example.
Further, using a gear type aging tester defined in JIS K 6257, the test piece was subjected to an aging test under three conditions of 165 ° C. × 14 days, 180 ° C. × 3 days, and 180 ° C. × 7 days.
A tensile test was performed on the test piece subjected to this aging test and the test piece not subjected to aging (initial product) using a tensile tester. The tensile test was performed at a normal temperature and a pulling speed of 500 mm / min.
With the tensile strength and breaking elongation of the initial product measured in this tensile test as 100%, respectively, the tensile strength and the residual ratio of breaking elongation after each aging test were obtained by calculation. The results are shown in Table 3.

(Abrasion resistance evaluation)
A DIN abrasion test defined in JIS K 6264-2 was performed on the rubber compositions of the examples and comparative examples after the aging test at 165 ° C. for 14 days. Moreover, the PICO abrasion test of JIS K 6264-2 regulation was implemented on 150 degreeC temperature conditions with respect to the rubber composition of each Example after a aging test of 180 degreeC x 7 days, and a comparative example. The results are shown in Table 4.

(Crack resistance evaluation)
5. Using the gear type aging tester specified in JIS K 6257, the aging test at 165 ° C. × 14 days, the 6.3 mm-thick test piece of Comparative Example and the aging test were not performed. The number of flexures until a crack was grown from 2 mm to 10 mm at room temperature was measured on a 3 mm-thick test piece based on the demature flex crack test method for vulcanized rubber and thermoplastic rubber specified in JIS K 6260. The results are shown in Table 4.

(Molding adhesiveness)
Two sheets (2 mm thickness) before cross-linking of the rubber compositions of each Example and Comparative Example were allowed to stand for one day at room temperature, and then bonded together. The results obtained were judged as “◎”, particularly as “◯” when there was no problem, and as “x” when there was a problem. The results are shown in Table 4.

※ 劣化が激しく測定不能であった。
※※耐クラック性について表中の「＞１０万回」とは１０万回の時点でもき裂が１０ｍｍに成長していなかったことを表す。また「１００回＞」とは１００回の時点ですでにき裂が１０ｍｍに成長していたことを表す。

* Measurement was impossible due to severe deterioration.
** Regarding crack resistance, “> 100,000 times” in the table means that the crack did not grow to 10 mm even after 100,000 times. “100 times>” means that the crack has already grown to 10 mm at the time of 100 times.

From the results of Table 4, ethylene / propylene / ethylene norbornene copolymer rubber containing 0.1 to 1.0% by weight of ethylene norbornene and 65% by weight or more of ethylene component is 50% of the polymer component of the rubber composition. % are used above, moreover, the rubber carbon black iodine adsorption 50 to 70 g / kg and DBP oil absorption amount 135~160cm ³ / 100g is contained 30 to 70 parts by weight per 100 parts by weight of the polymer components The composition has a heat resistant rubber composition that does not impair roll processability and molding adhesiveness as in the case of using rubber containing ethylene / propylene copolymer and ethylene / 1-octene copolymer. It can be seen that it can be excellent in resistance, crack resistance and wear resistance.

Claims (3)

An ethylene / propylene / ethylene norbornene copolymer rubber containing 65% by weight or more of ethylene and propylene and 0.1 to 1.0% by weight of ethylene norbornene is the total polymer component. used in more than 50 wt% will be made of carbon black iodine adsorption 50 to 70 g / kg and DBP oil absorption amount 135~160cm ³ / 100g is contained 30 to 70 parts by weight per 100 parts by weight of the total polymer component The rubber composition characterized by the above-mentioned.   A conveyor belt, wherein the rubber composition according to claim 1 is used in a belt body.   A heat-resistant belt, wherein the rubber composition according to claim 1 is used for a belt body, and is used for conveying a conveyed product at 150 ° C or higher.