JP2687552B2 - Ethylene / α-olefin / diene copolymer composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention was developed by adding an ethylene / α-olefin / diene copolymer composition used as a base polymer for rubber products, particularly a mineral oil-based oil. The present invention relates to an ethylene / α-olefin / diene copolymer composition for low hardness rubber.

[Conventional technology]

Ethylene / α-olefin / diene copolymers are widely used as base polymers for various rubber products such as industrial parts, insulating parts, civil engineering / building materials, tires and tubes.

These are spread in the range of 10 to 90 by JIS A or JIS C hardness tester, and such products usually contain various additives such as reinforcing agents, fillers, softening agents, vulcanization accelerators, vulcanizing agents, etc. , Can be obtained by adjusting the input amount. Of these, softeners, especially mineral oils, are added to adjust hardness and processability.

The amount of conventional oil added varies depending on the type and amount of other additives, but is generally 10 to 100 parts by weight with respect to 100 parts by weight of the ethylene / α-olefin / diene copolymer. Oil-extended ethylene / α-olefin / diene copolymers containing 100 parts by weight or less of oil with respect to 100 parts by weight of the copolymer are commercially available, but none have been added in excess of 100 parts by weight. This is because the miscibility of the copolymer and the oil is poor, and it is difficult to add a large amount of oil uniformly, and the oil-extended composition has a low viscosity and a water-candy shape, and the shape retention is poor. It becomes difficult to handle.

However, in recent years, the demand for low hardness rubber products has increased, and those having hardness of 20 to 30 are required. When a rubber product having such a low hardness, for example, a low hardness rubber product having a JIS A hardness tester of 30 or less is obtained, generally 100 parts by weight of an ethylene / α-olefin / diene copolymer is used as a softening agent. It is necessary to add 180 to 200 parts by weight of the oil as.

However, in this case, even if an oil-extended ethylene / α-olefin / diene copolymer to which 100 parts by weight of oil was previously added was used, 80 to 100 parts by weight of the oil to be added later was used as the base polymer. Large amounts of oil have to be added as compared to the copolymer and other additives. When attempting to knead these mixtures for this purpose using a closed kneading machine or the like, the miscibility of the copolymer and the reinforcing agent with the oil is poor, and slipping or the like makes the kneading difficult, and the kneading time Lengthening, reinforcing agents, fillers,
There are problems such as poor dispersion of the polymer and further deterioration of physical properties due to poor dispersion.

[Problems to be solved by the invention]

The object of the present invention is to solve the above problems, good shape retention, handleability and dispersibility, can be efficiently kneaded in a short time, as a result, a low hardness rubber product having excellent physical properties. To provide an ethylene / α-olefin / diene copolymer composition sufficient as a material for obtaining

[Means for solving the problem]

The present invention relates to (A) ethylene / α-olefin molar ratio
75/25 to 83/17, iodine value 5 to 50, intrinsic viscosity measured in decalin at 135 ° C [η] 3.2 to 5.5 dl / g ethylene / α-
Ethylene / α-characterized by adding 105 parts by weight or more of (B) mineral oil based oil to 100 parts by weight of olefin / diene copolymer
It is an olefin / diene copolymer composition.

The amount of mineral oil-based oil that can be added and extended to the ethylene / α-olefin / diene copolymer is related to the molecular weight of the base copolymer. Conventional oil-extended rubber uses a low molecular weight copolymer from the viewpoint of processability and the like, so that high elongation cannot be achieved.However, in the present invention, a high molecular weight copolymer having a specific composition is used as a base. By selecting so that a large amount of mineral oil can be added, high elongation can be achieved without lowering workability.

The ethylene / α-olefin / diene copolymer (A) used in the present invention is a random copolymer rubber composed of ethylene units, α-olefin units and diene units. As α-olefin, propylene, butene-
1, pentene-1, hexene-1, 4-methyl-pentene-1, octene-1, decene-1 and the like, among which propylene and butene-1 are preferable, and propylene is particularly preferable, and these are one or two. More than one seed can be used.

The ethylene / α-olefin / diene copolymer (A) used in the present invention has a molar ratio of ethylene / α-olefin of 75/25 to 83/17, preferably 76/24 to 80/20. By controlling the ethylene / α-olefin molar ratio in such a range, the copolymer composition of the present invention has good shape-retaining property, and the compounded vulcanized rubber having a hardness of 20 has a strength of 100 k
It can be kept above gf / cm ² .

As the diene, 1,4-hexadiene, 1,6-octadiene, 2-methyl-1,5-hexadiene, 6-methyl-
Chain non-conjugated dienes such as 1,5-heptadiene, 7-methyl-1,6-octadiene; cyclohexadiene, dicyclopentadiene, methyltetrahydroindene, 5-vinylnorbornene, 5-ethylidene-2-norbornene, 5- Non-conjugated dienes such as cyclic non-conjugated dienes such as methylene-2-norbornene, 5-isopropylidene-2-norbornene, 6-chloromethyl-5-isopropenyl-2-norbornene and the like, among which dicyclopentadiene, 1 , 4-hexadiene, 5-ethylidene-2-
Norbornene is preferred, and these can be used alone or in combination of two or more. The amount of diene is 5 in terms of iodine value.
50, preferably 7 to 30.

The intrinsic viscosity [η] measured in decalin at 135 ° C., which is an index of the molecular weight of the ethylene / α-olefin / diene copolymer (A), is 3.2 to 5.5 dl / g, preferably 3.7 to 5.0 dl / g. . By adjusting the molecular weight of the ethylene / α-olefin / diene copolymer (A) in such a range, the copolymer composition of the present invention has good shape-retaining property and further has a hardness of 20 and is compounded and vulcanized. The strength of rubber can be maintained at 100 kgf / cm ² or more.

The addition amount of the mineral oil-based oil (B) component is (A) component 100
The amount is 105 parts by weight or more, preferably 105 to 200 parts by weight, and most preferably 120 to 160 parts by weight with respect to parts by weight. This amount is increased or decreased depending on the hardness of the rubber product to be manufactured.

The ethylene / α-olefin / diene copolymer composition of the present invention is a composition obtained by adding a mineral oil-based oil (B) to the ethylene / α-olefin / diene copolymer (A). In order to add a large amount of oil to the ethylene / α-olefin / diene copolymer to extend it, after the polymerization step of the copolymer is completed, the mineral oil-based oil (B) is mixed with the polymerization solution to obtain a solvent. A gel-like material can be obtained by removing the. In the present invention, 1 part of the mineral oil-based oil (B) is used per 100 parts by weight of the ethylene / α-olefin / diene copolymer.
Although they are mixed in a proportion of 05 parts by weight or more, the copolymer and the oil are uniformly mixed with each other depending on the solvent in the polymerization liquid, so that even after the solvent is removed, the both are in a uniformly mixed state and a homogeneous composition is obtained.

The ethylene / α-olefin / diene copolymer composition of the present invention may contain other components such as a stabilizer in addition to the components (A) and (B).

The ethylene / α-olefin / diene copolymer composition of the present invention as described above is kneaded by blending a softening agent, a filler, a vulcanizing agent, a vulcanization aid, a vulcanization accelerator, and other additives. A rubber product with low hardness can be obtained by compounding rubber and vulcanizing it.

As the softening agent, for example, paraffin type, naphthene type,
Mineral oils such as aromatic oils; rosins such as tackifiers; glycols, etc. as long as they can be used for lowering hardness, preventing dispersion defects, improving processability, etc. It may be the same as the oil.
These softening agents are blended by post-adding an amount obtained by subtracting the amount used for oil extension from the amount necessary to obtain the desired hardness. For example, when obtaining a rubber product having a hardness of 20 to 30, 180 to 200 parts by weight of oil is required for 100 parts by weight of the copolymer as described above, but a copolymer in which 150 parts by weight of oil is preliminarily used is used. Then, the remaining 30 to 50 parts by weight is added later. When the amount of post-addition is zero, it is difficult to knead the copolymer composition and other additives, so 5 to 100 parts by weight relative to 100 parts by weight of the copolymer.
It is preferable to post-add parts by weight and knead.

Examples of the filler include general reinforcing agents and fillers such as carbon black and white clay, and those which can be used for improving mechanical properties such as tensile strength of rubber products or for increasing the amount can be used.

Examples of the vulcanizing agent include sulfur, organic peroxides, amines and the like. Examples of the vulcanization aid include zinc white, quinone oximes, ester-based cross-linking agents and the like. Examples of the vulcanization accelerator include organic sulfur compounds, and those that accelerate or delay the vulcanization of the ethylene / α-olefin / diene copolymer can be used.

Other additives include antiaging agents, processing aids, activators, colorants and the like. The above various additives may be used alone or in combination of two or more, and are mixed in appropriate amounts in consideration of the hardness and workability of the target low hardness rubber product.

The compounded rubber includes ethylene / α-olefin / diene copolymer compositions other than the ethylene / α-olefin / diene copolymer composition of the present invention, natural rubber, isoprene rubber, styrene / butadiene rubber, butadiene rubber, etc. One kind or two or more kinds of the different rubbers can be blended.

The compounded rubber thus compounded is kneaded by a kneader, an open roll, a kneader such as a closed kneader, and if necessary, a preform such as a ribbon or a pellet is formed by an extruder or the like, and then injection molding or compression press. And the like, and then vulcanized by heating at 130 to 250 ° C. This makes it possible to knead a low hardness compounded rubber containing a large amount of oil in a short time, and obtain a low hardness rubber product having excellent dispersibility and physical properties.

〔The invention's effect〕

As described above, the ethylene / α-olefin /
Since the diene copolymer composition was expanded by adding 105 parts by weight or more of the component (B) to 100 parts by weight of the component (A), when the compounded rubber was prepared, it was efficiently mixed with other components in a short time. It is possible to obtain a low hardness rubber product which can be kneaded and has excellent dispersibility and physical properties.

〔Example〕

Hereinafter, the present invention will be described based on examples. In each case,
Parts are parts by weight.

Example 1 Ethylene and propylene content was 75/25 in ethylene / propylene molar ratio, 5-ethylidene-2-norbornene content was 10 based on iodine number, and intrinsic viscosity measured in decalin at 135 ° C. [η] After the completion of the polymerization process of 3.7 dl / g ethylene / propylene / diene copolymer, 73% by weight of paraffin component as extension oil, 27% by weight of naphthene component, 0% by weight of aromatic component, mineral oil type process oil with an average molecular weight of 750 120 parts was added to 100 parts of the copolymer and the solvent was removed to obtain an oil-extended ethylene / propylene / diene copolymer composition.

This copolymer composition is pressed to form a bale having a size of 10 cm × 10 cm × 3 cm, a load of 68 g / cm ² is added thereto, and the temperature is 40 ° C.
The shape retention property was examined after leaving it for 24 hours under the condition. As a result, as shown in Table 1, good shape retention was obtained.

Example 2 In Example 1, the molecular weight of the ethylene / propylene / diene copolymer was adjusted to [eta] of 5.0 dl / g, and an extended ethylene / propylene / diene copolymer composition was obtained in the same manner as in Example 1. The shape retention was examined in the same manner as in Example 1. The results are shown in Table 1, and the shape retention was even better than that of Example 1.

Comparative Example 1 Shape retention was examined in the same manner as in Example 1 except that the molecular weight of the ethylene / propylene / diene copolymer was reduced to 2.9 dl / g with [η]. As a result, as shown in Table 1, the deformation was larger than that in Example 1 and the shape retention was poor.

Example 3 In Example 1, the ethylene / propylene molar ratio was changed to
The shape retention was examined in the same manner as in Example 1 except that the shape retention property was changed to 80/20. As a result, as shown in Table 1, even better shape retention than that in Example 1 was obtained.

Comparative Example 2 In Example 1, the ethylene / propylene molar ratio was changed to
The shape retention property was examined in the same manner as in Example 1 except that the shape retention property was changed to 70/30. As a result, as shown in Table 1, the shape retention property was lower than that of Example 1.

Example 4 Ingredients of ethylene and propylene were 78/22 in terms of ethylene / propylene molar ratio, 5-ethylidene-2-norbornene content was 10 based on iodine number, and intrinsic viscosity [η] measured in decalin at 135 ° C. After the completion of the polymerization step of the ethylene / propylene / diene copolymer having a concentration of 4.5 dl / g, 73% by weight of paraffin component, 27% by weight of naphthene component, 0% by weight of aromatic component as a extender oil, a mineral oil-based process oil with an average molecular weight of 750 160 parts with respect to 100 parts of the copolymer was added, the solvent was removed, and the extended oil-extended ethylene / propylene /
A diene copolymer composition (EPDM-1) was obtained.

260 parts of this EPDM-1 was put into a Banbury type closed-type kneader (capacity 1.7, manufactured by Kobe Steel Ltd.), and after masticating for 1 minute, 5 parts of zinc white, 1 part of stearic acid, SRF carbon (# 50, Asahi Carbon Co., Ltd., 50 parts, calcium carbonate 70 parts, activator (polyethylene glycol # 4000,
Wako Pure Chemical Industries, Ltd., 2 parts, processing aid (Structol WB-16, SCHILL & SEILACHER, trade name) 2 parts, and 20 parts of the mineral oil-based process oil used for the oil extension are put, and from the time when the peak power is reached. Knead for 3 minutes to clean,
The mixture was kneaded for another 1 minute, and after discharging, it was discharged with an 8-inch open roll. The kneading time and dispersibility (visual inspection) at this time were investigated. Table 2 shows the results.

After cooling the obtained blended kneaded product, it was wound around a roll and 1 part of MBT (Nocceller M) as a vulcanization accelerator, TMTD
(NOXCELLER TT) 0.5 part, DPTT (NOXCELLER TRA) 0.5
Department, ZnBDC (Noccer BZ) 1.5 parts, TeEDC (Noccer T
0.5 parts of TTE) and 1.2 parts of sulfur were added and kneaded, and a sample was prepared by press vulcanization at 170 ° C. for 7 minutes.

As the vulcanized rubber physical properties of the obtained sample, JIS K-630
Tensile stress at 300% elongation according to 1 (M300), tensile strength at break (T _B), elongation at break (E _B) and hardness (JIS A
Type) were measured (H _S).

The results are shown in Table 2, and the kneading time was short, the dispersion of the reinforcing agent and the like was very good, and the vulcanized rubber had high strength.

Example 5 The extension amount of the mineral oil-based process oil of Example 4 was 120 parts (EPDM
-2), except that the amount of the post-addition mineral oil-based process oil was changed to 60 parts.

The results are shown in Table 2, and the kneading time was short, the reinforcing agent was well dispersed, and the vulcanized rubber had high strength.

Comparative Example 3 The extension amount of the mineral oil-based process oil of Example 4 was 70 parts (EPDM-
The procedure of Example 4 was repeated, except that the amount of the post-addition mineral oil-based process oil was changed to 110 parts.

The results are shown in Table 2. As compared with Examples 4 and 5, the kneading time was very long, the dispersibility of the reinforcing agent was poor, and the vulcanized rubber strength was low.

Comparative Example 4 The extension amount of the mineral oil-based process oil of Example 4 was 100 parts (EPDM
-4), and the same procedure as in Example 4 was performed except that the amount of the post-addition mineral oil-based process oil was changed to 80 parts.

The results are shown in Table 2. As compared with Examples 4 and 5, the kneading time was longer, the dispersibility of the reinforcing agent or the like was slightly inferior, and the vulcanized rubber strength was slightly decreased.

Claims (1)

(57) [Claims] 1. A molar ratio of (A) ethylene / α-olefin
75/25 to 83/17, iodine value 5 to 50, intrinsic viscosity measured in decalin at 135 ° C [η] 3.2 to 5.5 dl / g ethylene / α-
Ethylene / α-characterized by adding 105 parts by weight or more of (B) mineral oil based oil to 100 parts by weight of olefin / diene copolymer
Olefin / diene copolymer composition.