JPH11279285A - Production of thermoplastic elastomer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an economical production process for a thermoplastic elastomer having excellent mechanical strength by means of a tightly sealable polymer mixer. SOLUTION: In a thermoplastic elastomer comprising a high ethylene content ethylene-propylene rubber an olefinic resin and a mineral oil, the mineral oil is preliminarily added to the high ethylene-content ethylene-propylene rubber and they are mixed in a tightly sealed mixing machine at a temperature preferably higher than the melting temperature of the olefinic resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to a method for economically producing thermoplastic elastomers having thermoplastic properties and excellent strength properties. More particularly, the present invention relates to vulcanization usually performed with rubber. A thermoplastic elastomer consisting of ethylene-propylene rubber and an olefin-based resin that has rubber-like mechanical properties without the need for rubber and can be molded with a thermoplastic resin molding machine. The present invention relates to a method for producing a thermoplastic elastomer, in which a mixture of ethylene and propylene rubber is used and mineral oil is added in a short time in order to further improve moldability.

[0002]

2. Description of the Related Art Normally, ethylene-propylene rubber is added with a reinforcing agent such as carbon black or inorganic filler, and has rubber-like mechanical properties that can withstand practical use unless vulcanized or cross-linked with sulfur or organic peroxide. Not expressed. However, the vulcanized product and the crosslinked product do not have thermoplasticity, so a troublesome processing step is required, and further, they cannot be recycled.

[0003] For this purpose, thermoplastic elastomers obtained by adding an olefin-based resin to ethylene-propylene rubber to impart thermoplasticity have been commercialized. In addition, ethylene
Japanese Patent Publication No. Sho 53-34210 proposes a method in which an olefin resin is added to propylene rubber and the thermoplastic resin and rubber mechanical properties are imparted by lightly crosslinking the resin.

[0004] Furthermore, a mixture of ethylene-propylene rubber and an olefin resin to which a mineral oil-based softener is added is dynamically heat-treated in the presence of an organic peroxide to improve the fluidity of the olefin-based resin. A method for producing a thermoplastic elastomer is proposed in Japanese Patent Publication No. 56-15741.

[0005]

It is already known that a thermoplastic elastomer having thermoplasticity and rubber-like mechanical properties can be produced from ethylene-propylene rubber and an olefin-based resin. A proposal has been made.

[0006] However, olefin-based thermoplastic elastomers often lack rubber-like mechanical properties, especially mechanical strength properties in practical use, and are restricted in their use. In order to improve this, there is a method of increasing the amount of the olefin-based resin to be added, but in this case, flexibility, which is a rubber-like property, is lost, which is not preferable. In addition, there is a method using ethylene-propylene rubber having a high ethylene content.In this case, if mineral oil is added with an internal mixer to improve fluidity, the cohesive force of the ethylene-propylene rubber is high, and mineral oil is added. Oil does not easily enter the ethylene / propylene rubber and takes a long time to mix. When observing the mixed state, ethylene-propylene rubber with a small ethylene content becomes a small mass with a rotary blade, but ethylene-propylene rubber with a large ethylene content becomes a large mass, and mineral oil adheres to this surface,
It takes a long time to mix because the lumps to which the mineral oil adheres run idle.

[0007] This phenomenon occurs when mineral oil is added to ethylene-propylene rubber having a high ethylene content because the rubber has a strong cohesive force and a low filling rate in an internal mixer. Even if an olefin-based resin is added to increase the filling rate, it cannot be improved because the olefin-based resin has poor compatibility with minerals. An object of the present invention is to solve the above-mentioned problems and to produce a thermoplastic elastomer having excellent mechanical strength characteristics in an internal mixer.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention requires that mineral oil be mixed in advance with ethylene-propylene rubber having a high ethylene content, and then the olefin resin be mixed with an olefin resin in a closed mixer. A method for producing an olefin-based thermoplastic elastomer, characterized by adding a filler or a cross-linking agent as necessary and mixing at a temperature equal to or higher than the melting temperature of the olefin-based resin.

The ethylene / propylene rubber in the present invention is a copolymer of ethylene and propylene and / or an ethylene-propylene-non-conjugated diene copolymer, wherein the non-conjugated diene is ethylidene norbornene, zinc lopantadiene, -4 hexadiene is preferred. In these ethylene-propylene rubbers, the ethylene content is 6
3 to 75% by weight, preferably 65 to 73% by weight.
If it is less than 62% by weight, excellent mechanical strength properties cannot be exhibited, and if it is more than 76% by weight, the viscosity of the copolymer-containing solution when producing ethylene / propylene rubber becomes high, and it is difficult to produce ethylene / propylene rubber. become.

The olefin resin is polyethylene, polypropylene, propylene-α-olefin copolymer or a mixture thereof, and preferably has a melt flow rate (ASTM-D-1238) at 230 ° C. of 5 to 40. The proportion of ethylene-propylene rubber to olefin resin is 40 to 85% by weight, preferably 45 to 80% by weight of ethylene / propylene rubber, and 15 to 60% by weight, preferably 20 to 55% by weight of olefin resin. is there. When the content of the olefin-based resin is 14% by weight or less, mechanical strength characteristics that can withstand practical use cannot be obtained, and thermoplasticity is lost. When the content is 61% by weight or more, flexibility is lost and rubber-like performance is lost.

[0011] Mineral oil is a high-boiling petroleum fraction usually used to improve the processability of rubber. The amount of mineral oil added is a total of 100 parts of ethylene-propylene rubber and olefin resin.
5 to 100 parts by weight, preferably 10 to 90 parts by weight. When the amount is less than 4 parts by weight, there is no effect of improving the workability and 1
If the amount is more than 01 parts by weight, the mechanical strength is greatly reduced, and a thermoplastic elastomer which can withstand practical use cannot be obtained. Ethylene / propylene rubber premixed with this mineral oil can be obtained by using an open roll or a closed mixer with an increased filling rate of ethylene / propylene rubber alone, but ethylene / propylene rubber is obtained by using an organic solvent such as hexane. It is more economical to use oil-extended ethylene propylene rubber obtained by adding mineral oil into the polymerization solution, since it polymerizes in the polymerization solution.

Further, a filler such as carbon black, calcium carbonate, talc or the like can be used in an amount of 0 to 100 parts by weight based on a total of 100 of the ethylene / propylene rubber and the olefin resin. More than 101 parts by weight of filler
It is not preferable because it loses rubber-like performance. In order to further impart rubber-like properties, a crosslinking agent such as an organic peroxide or sulfur may be added in an amount of 0 to 0.7 parts by weight based on a total of 100 of the ethylene-propylene rubber and the olefin-based resin.
Addition of 0.8 parts by weight or more is not preferable because it loses thermoplasticity. Furthermore, even if a heat-resistant stabilizer or an ultraviolet absorber conventionally used in rubber or plastic is added, the effect of the present invention is not affected at all.

The closed mixer according to the present invention is a Banbury mixer or a kneader which generally has two rotors having blades in a closed case and performs mixing while pressurizing with a ram. .

[0014]

Embodiments of the present invention will be described below. Example 1 and Comparative Examples 1-4. Pressurized kneader preheated to 160 ° C (Moriyama Seisakusho, internal volume: 3 liters)
The materials shown in Table 1 were mixed at a ratio shown in Table 2 at a total weight of 2,000 g (volume filling rate of contents: 76%) at a speed of 40 revolutions per minute by a rotor. Comparative Examples 1 and 3
Ethylene / propylene rubber was charged, and as soon as the rubber was broken, polypropylene, a heat stabilizer and carbon black were added. Mixing was then continued and mineral oil was added when the torque was at a maximum and began to drop. Although the torque is reduced by the addition of the mineral oil, if the mixing is continued, the torque increases again due to the mineral oil being mixed into the contents. After the torque reached the maximum, the contents were discharged by mixing for another 2 minutes. The time from the introduction and discharge of the ethylene / propylene rubber was defined as the mixing time. In Comparative Examples 2 and 4, ethylene-propylene rubber was charged, and mineral oil was added as soon as the rubber was broken. Thereafter, mixing was continued, and when the torque reached a maximum and began to drop, polypropylene, a heat stabilizer and carbon black were added and mixing was continued. The torque is at its maximum 2
Discharged after minutes. In Example 1, an ethylene-propylene rubber having a high ethylene content containing mineral oil was charged in advance, and immediately after the rubber was broken, polypropylene, a heat-resistant stabilizer and carbon black were added and discharged 2 minutes after the torque reached the maximum. . Table 2 shows the mixing time and the temperature at the time of discharge. The obtained mixture was placed in a mold at 200 ° C., compressed, cooled to 20 ° C. to form a seal having a thickness of 1 mm, and the performance was described in Table 2. MFR (melt flow rate) is ASTM-D-1238, others are JIS
-Measured according to K6301. Mixtures using ethylene / propylene rubber with a high ethylene content have excellent mechanical strength properties, but the mixing time of mineral oil is long and the mixing time is long. Ethylene propylene rubber with a high ethylene content containing mineral oil in advance has excellent mechanical strength characteristics and can shorten the mixing time.

Example 2 and Comparative Examples 5-7. Under the same kneader conditions as in Example 1, the materials shown in Table 1 and the total weight of 2500 g at the ratios shown in Table 3 (the inner product filling rate of the contents: 76
%). In Comparative Example 5, ethylene / propylene rubber was charged, and as soon as the rubber was crushed, polypropylene and a heat stabilizer were added. Mineral oil was added when the torque reached a maximum and began to drop. After mixing for 20 minutes, the torque did not increase and it was difficult to mix mineral oil. The effluent did not clump. In Comparative Example 6, mineral oil and calcium carbonate were simultaneously added to Comparative Example 5 after the addition of the polypropylene and the heat stabilizer. Mix for 20 minutes, but do not clump. Comparative Example 7 shows that after adding the polypropylene and the heat stabilizer, half of the mineral oil and calcium carbonate were added,
When the torque reached a maximum and began to drop, the other half was added. Mixing was continued and drained 2 minutes after the torque was at its maximum. In Example 2, ethylene-propylene rubber having a high ethylene content containing mineral oil in advance was charged, and as soon as the rubber was broken, polypropylene and a heat stabilizer were added. When the torque reached a maximum and began to fall, calcium carbonate was added and discharged 2 minutes after the torque reached a maximum again. Table 3 shows the mixing times and the performance of the resulting mixtures.
It described in. The effect of the present invention is more remarkable as the mixture contains more mineral oil.

Example 3 and Comparative Example 8 In Comparative Example 8, ethylene-propylene rubber, polypropylene, heat stabilizer, carbon black, and mineral oil were added in Comparative Example 3, and a crosslinking agent was added immediately after the torque reached the maximum, and then mixed for 3 minutes and discharged. . In Example 3, the same operation as Comparative Example 8 was performed after adding the mineral oil-containing ethylene / propylene rubber, polypropylene, heat stabilizer and carbon black in Example 1. Table 4 shows the mixing time and the performance of the obtained mixture. The addition of the crosslinking agent has no effect on the effects of the present invention.

[0017]

[Table 1]

[0018]

[Table 2]

[0019]

[Table 3]

[0020]

[Table 4]

[0021]

According to the present invention, if a high ethylene content ethylene / propylene rubber is used in a thermoplastic elastomer composed of ethylene / propylene rubber, an olefin-based resin and mineral oil, excellent mechanical strength characteristics can be obtained. When mineral oil is directly added by a mixer, it takes a long time to mix the mineral oil. If an ethylene-propylene rubber having a high ethylene content to which mineral oil is added in advance is used, mixing can be performed in a short time, and a thermoplastic elastomer excellent in mechanical strength characteristics can be economically produced.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshitaka Kondo 4-17-22 Miyanogidai, Hanamigawa-ku, Chiba-shi, Chiba Pref. No. Uniparis 504 Masuzawa Chemical Sales Co., Ltd.

Claims (4)

[Claims] 1. An ethylene content of 63 to 75% by weight
A thermoplastic elastomer comprising 40 to 85% by weight of an ethylene-propylene rubber, 15 to 60% by weight of an olefin-based resin and 5 to 100 parts by weight of a mineral oil with respect to a total of 100 ethylene-propylene rubbers and an olefin-based resin. 3. The method for producing a thermoplastic elastomer, wherein the mineral oil is mixed in advance with the ethylene-propylene rubber, and then mixed at a temperature higher than the melting temperature of the olefin-based resin in an internal mixer. 2. The method for producing a thermoplastic elastomer according to claim 1, wherein the olefin-based resin is polyethylene, polypropylene, propylene-α-olefin copolymer or a mixture thereof. 3. The method for producing a thermoplastic elastomer according to claim 1, wherein the filler is contained in an amount of 0 to 100 parts by weight based on a total of 100 of the ethylene-propylene rubber and the olefin-based resin. 4. The process for producing a thermoplastic elastomer according to claim 1, wherein the crosslinking agent is contained in an amount of 0 to 0.7 parts by weight based on a total of 100 of the ethylene-propylene rubber and the olefin resin.