JPH07292167A - Softening agent as admixture for rubber and rubber composition containing the same - Google Patents

Abstract

PURPOSE:To obtain a softening agent as an admixture for rubber, less apt to cause the reduction of viscoelasticity of a rubber composition kept at a high temperature and capable of keeping the softness of the rubber composition even under the high-temperature condition and a rubber composition containing this softening agent and excellent in high-temperature properties. CONSTITUTION:This softening agent (e.g. tetramer or pentamer of 1-decene) as an admixture for rubber contains a 6 to 14C alpha-olefin oligomer and/or its hydrogenated compound. The rubber composition contains 100 pts.wt. rubber (e.g. an ethylene-propylene-diene terpolymer) and 5 to 200 pts.wt. the above alpha-olefin oligomer and/or its hydrogenated compound.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber compounding softening agent and a rubber composition containing the softening agent. More specifically, the present invention relates to a rubber compounding softening agent capable of maintaining the viscoelasticity, which is a characteristic of rubber, even in a high temperature environment, and a rubber composition excellent in high temperature performance, which is obtained by compounding the softening agent. INDUSTRIAL APPLICABILITY The present invention is particularly preferably used in the field of rubber industry and the fields such as automobiles, machinery and electric industry which are associated therewith.

[0002]

2. Description of the Related Art When processing rubber, the purpose is to reduce the viscosity of the raw material mixture or the kneading temperature to improve work efficiency and processing performance, or to improve the flexibility of the rubber product produced. Is used as a softening agent. However, conventionally, a rubber product containing a softening agent has a drawback that its viscoelasticity is lowered at a high temperature.
This decrease in viscoelasticity causes an increase in the residual strain value and causes various problems such as deterioration in vibration isolation performance. Therefore, when it is desired to obtain a rubber product which is less likely to be deteriorated in viscoelasticity under high temperature and has excellent high temperature performance, conventionally, paraffinic mineral oil or naphthene having a relatively high viscosity (for example, a kinematic viscosity at 100 ° C. of about 20 to 35 cSt) is used. A mineral oil was used as a softening agent. However, even when these softening agents are used, the decrease in viscoelasticity cannot be sufficiently suppressed at a high temperature of 100 ° C. or higher. As described above, conventionally, when a softening agent is blended with a rubber product, it is difficult to achieve high temperature performance at the same time, and thus the rubber product cannot be used under high temperature, or if it can be used, its use There was a problem that the method and usage conditions were limited and complicated.

[0003]

Under such circumstances, the present invention maintains the viscoelasticity, which is a characteristic of rubber, well even at high temperatures, and provides a rubber composition having a wide temperature range from low temperatures to high temperatures. It was made for the purpose of providing a softening agent for rubber compounding capable of retaining flexibility and a rubber composition excellent in high-temperature performance obtained by compounding the softening agent.

[0004]

Means for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the present inventors have found that the carbon number is 6 to 1
The α-olefin oligomer and / or hydride thereof of 4 can be used as a softening agent for rubber compounding in accordance with the above-mentioned object, and further, when the α-olefin oligomer and / or its hydride is compounded in a specific ratio, It has been found that a rubber composition having excellent physical properties can be obtained. The present invention has been completed based on such findings. That is, the present invention provides a softener for compounding rubber, which contains an α-olefin oligomer having 6 to 14 carbon atoms and / or a hydride thereof. Further, the present invention is
There is also provided a rubber composition containing 100 parts by weight of rubber and 5 to 200 parts by weight of an α-olefin oligomer having 6 to 14 carbon atoms and / or a hydride thereof.

The main component of the softening agent of the present invention is 6 to 6 carbon atoms.
The α-olefin oligomer of 14 and / or its hydride means an oligomer whose repeating unit is an α-olefin having 6 to 14 carbon atoms, a hydride of the oligomer, or a mixture thereof. Here, the oligomer whose repeating unit is an α-olefin having 6 to 14 carbon atoms includes not only a homopolymer but also a copolymer composed of two or more kinds of α-olefin repeating units. Further, the above mixture also includes a mixture of α-olefin oligomer and its hydride, a mixture of two or more types of α-olefin oligomer, and a mixture of two or more types of α-olefin oligomer hydride. It

The α-olefin constituting the repeating unit of the α-olefin oligomer needs to have 6 to 14 carbon atoms, and more preferably has 8 to 12 carbon atoms. The type of α-olefin is not particularly limited, and it may be any of aliphatic type, alicyclic type, and aromatic type. Specific examples of the α-olefin include, for example, 1-hexene, 1-hexene in the case of a linear aliphatic α-olefin.
Heptene, 1-octene, 1-nonene, 1-decene, 1
-Undecene, 1-dodecene, 1-tridecene, and 1
Examples of the branched aliphatic α-olefin include tetradecene and the like. Examples of the branched aliphatic α-olefin include those having an alkyl group in the side chain, and those having an iso type or neo type having a vinyl group or a vinylidene group. Α constituting the repeating unit
Of the olefins, the preferred ones are aliphatic
Particularly preferred is an aliphatic α-olefin having 10 carbon atoms.

The molecular weight of the α-olefin oligomer is not particularly limited as long as it can be generally recognized as an oligomer, but the number average molecular weight is usually 400 to 1600,
Preferably 500-1200, particularly preferably 500-
950. The kinematic viscosity of the α-olefin oligomer and / or its hydride at 100 ° C. has a lower limit of 8 cSt (centistokes) (8 ×) to prevent bleeding.
It is preferably 10 ⁻⁶ m ² s ⁻¹ ) or more. If the kinematic viscosity is less than 8 cSt, bleeding tends to occur on the surface of the rubber composition. On the other hand, the upper limit of the kinematic viscosity is 35 cSt (35 × 10 ⁻⁶ m ² s) in order to improve the processing performance.
^-1 ) or less, preferably 20 cSt (20 × 10
^-6 m ² s ^-1 ) or less is particularly preferable. If the kinematic viscosity exceeds 35 cSt, the processing performance tends to be adversely affected, such as the dispersibility of the compounding agent and the vulcanizing agent decreasing. Further, evaporation loss of α-olefin oligomer and / or its hydride (JIS K2220, 150 ° C)
Is preferably 5% by weight or less from the viewpoint of preventing deterioration at high temperatures and smoking during vulcanization.
Considering the above conditions, as the softener of the present invention,
A tetramer, a pentamer of 1-decene, or a mixture containing these as a main component is particularly preferable. The α-olefin oligomer having 6 to 14 carbon atoms and its hydride used in the present invention are known compounds, and a linear α-olefin obtained by low polymerization of ethylene or thermal decomposition of wax is used as a cation. It is produced by a method such as polymerization, but the production method is not particularly limited. These can be obtained by a conventionally known method, and a commercially available product may be used.

The softening agent of the present invention has a carbon number of 6 to 6 as described above.
Although it contains 14 α-olefin oligomers and / or hydrides thereof as a main component, it may be mixed with a usual softening agent such as a mineral oil type or a synthetic oil type in a range of less than 50% by weight. Further, a general additive such as an antiaging agent may be blended as long as the object of the present invention is not impaired.

The rubber to which the softening agent of the present invention can be added is not particularly limited, and may be natural rubber, synthetic rubber or blended rubber. Examples of synthetic rubbers include styrene-butadiene rubber, acrylonitrile rubber, butadiene rubber, chloroprene rubber, isobutylene-isoprene rubber, polysulfide rubber, silicone rubber, fluororubber,
Examples thereof include urethane rubber, stereo rubber, isoprene rubber, ethylene-propylene-diene terpolymer (EPDM), and rubbers obtained by blending these. Of these, isobutylene-isoprene rubber, isoprene rubber,
And an ethylene-propylene-diene terpolymer are preferable, and an ethylene-propylene-diene terpolymer is particularly preferable.

The lower limit of the blending ratio of the softening agent of the present invention is 100% rubber in order to sufficiently exert the effect as a softening agent.
The amount of the α-olefin oligomer having 6 to 14 carbon atoms and / or its hydride is usually 5 parts by weight or more, preferably 50 parts by weight or more, based on parts by weight. When the blending ratio of the softening agent is less than 5 parts by weight, the effect as the softening agent is often not sufficiently exhibited. On the other hand, the upper limit of the blending ratio of the softening agent of the present invention is, in order to keep the balance of physical properties of the produced rubber composition moderate, with respect to 100 parts by weight of the rubber, an α-olefin oligomer having 6 to 14 carbon atoms and / or Or, as a hydride thereof, usually 200 parts by weight or less, preferably 1
20 parts by weight or less. When the blending ratio of the softening agent exceeds 200 parts by weight, the physical property balance of the rubber composition is likely to be lost, and, for example, hardness and tensile strength are extremely reduced.

In the present invention, together with the softening agent of the present invention,
Fillers / reinforcing agents (for example, carbon black, zinc white, stearic acid, calcium carbonate, etc.), antioxidants / stabilizers (for example, aldehyde-ketone-amine reaction products, imidazoles, etc.) within the range that does not impair the object of the present invention. , Phenols, derivatives thereof, etc., which are commonly used, can be added to rubber. Further, the vulcanizing agent and the vulcanization accelerator are not particularly limited, and for example, commonly used vulcanizing agents such as sulfurs, thiazoles, sulfenamides and thiurams can be appropriately used.

The softening agent of the present invention can be used in the same manner as the conventionally known softening agents. Explaining along the general rubber product processing steps, a roll mill in which the softening agent of the present invention, another compounding agent, a vulcanizing agent, and a vulcanization accelerator are added to rubber masticated as necessary , Kneading with a closed type mixer or a continuous type mixer, and then molding, assembling, and crosslinking (vulcanization) to obtain a final rubber product.

The rubber composition of the present invention is a rubber composition obtained by blending the softening agent of the present invention with rubber in the above-mentioned predetermined ratio. This rubber composition has excellent physical properties particularly obtained by the softening agent of the present invention, that is, physical properties such that viscoelasticity is less likely to decrease at high temperatures, and other physical properties required for rubber products (for example, hardness and tensile strength). Since it has a particularly good balance with (1), it is one of the preferred modes of use from a practical viewpoint. In the rubber composition of the present invention, the rubber and the softening agent of the present invention are mixed in the above-mentioned predetermined mixing ratio, and if necessary, other general compounding agents, vulcanizing agents, vulcanization accelerators, etc. may be added. Can be obtained. However, in the rubber composition of the present invention,
Not only the mixture obtained by the above operation, but also a molded product after the kneading treatment and a final rubber product after crosslinking.
The specific method for obtaining the rubber composition is not particularly limited, and conventionally known processing methods for rubber products may be adopted in accordance with the above-described method of using the softening agent of the present invention.

[0014]

The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples.

Softeners used in Examples and Comparative Examples In Examples and Comparative Examples, the following oils A to E were used as softeners. Here, A oil and B oil correspond to the softening agent of the present invention. The properties of each softening agent are shown in Table 1. A oil: an α-olefin oligomer consisting of 1-decene tetramer and pentamer B oil: A softening agent consisting of 80% by weight of A oil and 20% by weight of naphthenic mineral oil C oil: paraffinic mineral oil D oil: paraffin Mineral oil E oil: naphthenic mineral oil

[0016]

[Table 1]

Example 1 Ethylene-propylene-diene terpolymer (EPD)
M) 50 parts by weight of A oil as a softening agent, 100 parts by weight of carbon black, 5 parts by weight of zinc white, relative to 100 parts by weight of M)
And 1 part by weight of stearic acid were added and kneaded with a Banbury mixer. To the resulting kneaded product, 1.5 parts by weight of sulfur, 1 part by weight of vulcanization accelerator A, and 0.5 parts by weight of vulcanization accelerator B were further added to 100 parts by weight of EPDM, and a mixing roll machine was used. Was kneaded to obtain an unvulcanized rubber. This unvulcanized rubber was vulcanized and molded in a vulcanizing press at 160 ° C. for 30 minutes to obtain a vulcanized rubber. In the above operation, Keltan 812 (diene component: ethylidene norbornene) manufactured by Holland DSM Co., Ltd. was used as EPDM, Asahi Carbon manufactured by HAF was used as carbon black, and Sakai Kagaku Kogyo, Zinc Hua No. 3 was used as zinc white. As the stearic acid, one from Nippon Oil & Fats was used, as the sulfur, Hosoi Chemical Co., Ltd., powdered sulfur (S ₈ ) was used, and as the vulcanization accelerator A, Sanshin Chemical Co., Ltd., Sancella TT (thiurams) was used. As the vulcanization accelerator B, Sanshin Chemical Co., Ltd.
(Thiazoles) were used. Initial physical properties of the vulcanized rubber (J
According to IS K6301, tensile strength was a No. 3 dumbbell-shaped sample piece, and hardness was A type. ), Compression set test (JIS K6301), low temperature torsion test (JI
SK6301) and the evaluation results of the amount of oil smoke generated in the vulcanization process are shown in Table 3.

Examples 2 to 4, Comparative Examples 1 to 6 Example 1 except that the type and blending ratio of the softening agent for rubber were changed.
A vulcanized rubber was produced in the same manner as in (1) and tested. Table 2 shows the composition of each rubber composition, and Table 3 shows the test results.
Shown in the table.

[0019]

[Table 2]

* 1: Keltan, manufactured by DSM of the Netherlands
812 (diene component: ethylidene norbornene) * 2: made by Asahi Carbon, HAF * 3: made by Sakai Chemical Industry, Zinc Hua No. 3 * 4: stearic acid made by NOF Corporation * 5: made by Hosoi Chemical Industry, powdered sulfur (S ₈ ) * 6: Sanshin Kagaku, Sansera TT (thiurams) * 7: Sanshin Kagaku, Sansera M (thiazoles)

[0021]

[Table 3]

[0022]

[Table 4]

* 8, * 9, * 11: JIS K6301
Obeyed. For the tensile strength, a No. 3 dumbbell-shaped sample piece was used, and the hardness was A type. * 10: ◎ almost none, ○ few, △ somewhat large, × many

[0024]

The softening agent for rubber compounding of the present invention has a peculiar property that it is unlikely to cause a decrease in viscoelasticity of a rubber product placed in a high temperature environment. Therefore, the rubber composition containing the softening agent does not easily increase the residual strain value at high temperature, and thus it is possible to solve the problems such as deterioration of vibration damping performance and deterioration of durability which occur at high temperature. From the results of the examples shown in Table 3, it can be seen that the compression set under high temperature (120 ° C., 48 hours) is more excellent in the examples than in the comparative examples. Examples containing 50 parts by weight of the softening agent of the present invention (Examples 1 and 3) and conventional softening agents were used.
Comparing the compression set (120 ° C., 48 hours) between the comparative examples (Comparative Examples 1, 3, 5) in which 0 parts by weight was compounded, Examples 1 and 3 were 18%, while Comparative Example 1 And 3 is 24%
Comparative Example 5 was 25%. In addition, Examples (Examples 2 and 4) in which 100 parts by weight of the softening agent of the present invention were blended and Comparative Examples (Comparative Example 2, in which 100 parts by weight of conventional softening agent were blended
4 and 6), the second embodiment is 28%.
While Example 4 was 29%, Comparative Examples 2 and 4 were 33%, and Comparative Example 6 was 35%. This result supports that the rubber composition was provided with excellent high-temperature performance by the softening agent of the present invention.

The results of the examples show the following additional effects. However, the original purpose of the present invention is to impart excellent high-temperature performance to the rubber composition, and the effects described below are not essential conditions for the establishment of the present invention. From the results of the low temperature torsion test in Table 3, it is understood that the flexibility of the rubber composition at a low temperature is also excellent in Examples as compared with Comparative Examples. That is, an example (Examples 1 and 3) in which 50 parts by weight of the softener of the present invention was blended and a comparative example (Comparative Example 1, in which 50 parts by weight of a conventional softener were blended
Even when compared between 3 and 5), the softening agent of the present invention is 100
Even when the examples (Examples 2 and 4) containing 100 parts by weight of the conventional softening agent and the comparative examples (Comparative Examples 2, 4 and 6) containing 100 parts by weight of the conventional softener are compared, T ₁₀ and T ₁₀₀ are reached. The temperatures are lower in the examples. According to these results, the softening agent of the present invention is capable of retaining the flexibility of the rubber composition over a wide temperature range from low temperature to high temperature, and, in turn, a high-performance rubber having little change in physical properties with changes in temperature conditions. A composition can be provided.

Further, looking at the oily smoke observation results in Table 3, when the softening agent of the present invention is used, an additional effect that the amount of oily smoke generated in the vulcanization step is obviously small is recognized. Since the oily smoke generated in the vulcanization step of the rubber composition is accompanied by an offensive odor or an irritating odor, it is preferable that the generated amount is as small as possible. Therefore, the present invention has another excellent effect that the working efficiency can be improved or the working environment can be improved by simplifying the oil and smoke discharging device in the processing step of the rubber composition. Is recognized.

Claims (5)

[Claims] 1. A softening agent for rubber compounding, which comprises an α-olefin oligomer having 6 to 14 carbon atoms and / or a hydride thereof. 2. The softening agent for rubber compounding according to claim 1, wherein the α-olefin oligomer having 6 to 14 carbon atoms and / or its hydride has a kinematic viscosity at 100 ° C. of 8 to 35 cSt. 3. 100 parts by weight of rubber and 6 to 14 carbon atoms
Α-olefin oligomer and / or hydride thereof 5
A rubber composition containing 200 to 200 parts by weight. 4. The rubber composition according to claim 3, wherein the α-olefin oligomer having 6 to 14 carbon atoms and / or its hydride has a kinematic viscosity at 100 ° C. of 8 to 35 cSt. 5. The rubber is isobutylene-isoprene rubber,
The rubber composition according to claim 3, which is at least one selected from the group consisting of isoprene rubber and an ethylene-propylene-diene terpolymer.