JP2005263842A - ETHYLENE-alpha-OLEFIN-NONCONJUGATED DIENE COPOLYMER RUBBER AND COMPOSITION FOR SPONGE - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ethylene-α-olefin-nonconjugated diene copolymer rubber which excels in the shape retention, the kneading processability, and additionally compression set of an extrusion molded rubber without using an expensive specific diene component. <P>SOLUTION: The ethylene-α-olefin-nonconjugated diene copolymer rubber contains a specific high-molecular-weight component and a specific low-molecular-weight component and has an α-olefin content of 35-55 wt.% when the sum of ethylene and the α-olefin is taken as 100 wt.%, a Mooney viscosity (ML<SB>1+4</SB>121°C) of 135-170, a nonconjugated diene-derived unit in the copolymer rubber of 7-15 wt.%, a nonconjugated diene content ratio of the high-molecular-weight component to the low-molecular-weight component of 0.9-1.1, and a ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by GPC of 3.5-5.5. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ethylene-α-olefin-nonconjugated diene copolymer rubber and composition for sponge. More specifically, the present invention relates to an ethylene-α-olefin-nonconjugated diene copolymer rubber having excellent shape retention and kneading processability of an extrusion-molded sponge rubber and having a small compression set. is there.

  Since ethylene-α-olefin-nonconjugated diene copolymer rubber has excellent properties such as heat resistance, weather resistance, ozone resistance, etc., as automotive materials, building materials, industrial materials, electric wire materials, etc. Widely used, it is used in large amounts for automotive door and trunk seal sponge applications.

  However, since these materials are highly cost competitive, rationalization and shortening of the processing process are progressing, and in the conventional ethylene-α-olefin-nonconjugated diene copolymer rubber, the molecular weight distribution is narrowed to shorten the kneading time, If the molecular weight is lowered, the shape retention characteristics deteriorate in the extrusion process, and the required shape may not be obtained. Conversely, if the molecular weight distribution is increased or the molecular weight is increased in order to improve the shape retention characteristics, the time required for kneading becomes longer or the surface of the extruded material is deteriorated due to insufficient kneading. There has been a demand for an ethylene-α-olefin-nonconjugated diene copolymer rubber that can be kneaded for a short time with improved balance of kneadability and shape retention of olefin-nonconjugated diene copolymer rubber and has excellent shape retention characteristics. For seal sponge applications, there has been a demand for ethylene-α-olefin-nonconjugated diene copolymer rubber having a property excellent in compression set.

  In order to meet such needs, proposals have been made to improve the balance by giving a branch to the entire copolymer rubber using a narrow molecular weight distribution structure and a special diene component as the fourth component (Patent Document 1). reference.). In addition, for the purpose of improving compression set, it has also been proposed to increase the molecular weight (ML viscosity) to such an extent that the surface skin is not roughened (see Patent Document 2).

Japanese translation of PCT publication No. 2002-507228 Japanese Patent Laid-Open No. 03-20339

  In such a situation, the problem to be solved by the present invention is that it does not use an expensive and special diene component, is excellent in shape retention and kneadability of extruded rubber, and has a small compression set. The present invention provides an ethylene-α-olefin-nonconjugated diene copolymer rubber having the following formula.

The present invention is an ethylene-α-olefin-nonconjugated diene copolymer rubber containing a high molecular weight component and a low molecular weight component, and the α-olefin content when the total of ethylene and α-olefin is 100% by weight. 35 to 55% by weight, Mooney viscosity (ML _{1 + 4} 121 ° C.) is 135 to 170, non-conjugated diene-derived units in the copolymer rubber are 7 to 15% by weight, and a high molecular weight component and a low molecular weight component The non-conjugated diene content ratio is 0.9 to 1.1, and the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by GPC is 3.5 to 5.5. This relates to an ethylene-α-olefin-nonconjugated diene copolymer rubber.
High molecular weight component: ML viscosity of a composition in which the α-olefin content is 35 to 50% by weight when the total of ethylene and α-olefin is 100% by weight, and 70 parts by weight of paraffin oil is mixed with 100 parts by weight of rubber. Is 25 to 45, and the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) measured by GPC is 3.5 to 5.0.
Low molecular weight component: α-olefin content is 40 to 60% by weight when the total of ethylene and α-olefin is 100% by weight

  According to the present invention, an ethylene-α-olefin-nonconjugated diene copolymer having the characteristics of extruding rubber having excellent shape retention and kneading processability and excellent compression set without using an expensive special diene component Rubber can be provided.

The ethylene-α-olefin-nonconjugated diene copolymer rubber of the present invention contains a high molecular weight component and a low molecular weight component. As a whole, the total amount of ethylene and α-olefin is 100% by weight. The α-olefin content is 35 to 55% by weight, the Mooney viscosity (ML _{1 + 4} 121 ° C.) is 135 to 170, the non-conjugated diene-derived unit in the copolymer rubber is 7 to 15% by weight, and the high molecular weight The non-conjugated diene content ratio of the component and the low molecular weight component is 0.9 to 1.1, and the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by GPC is 3.5 to This is an ethylene-α-olefin-nonconjugated diene copolymer rubber of 5.5. Examples of the α-olefin include propylene, butene, hexene, octene and the like. Among these, propylene and butene are preferable from the viewpoint of availability and cost.

  Non-conjugated diene monomers include 5-ethylidene-2-norbornene, 1,4-hexadiene, 1,5-hexadiene, 1,5-heptadiene, 1,6-heptadiene, 1,6-octadiene, 1,7-octadiene 1,7-nonadiene, 1,8-nonadiene, 1,8-decadiene, 1,9-decadiene, 1,12-tetradecadiene, 1,13-tetradecadiene, 3-methyl-1,4-hexadiene 3-methyl-1,5-hexadiene, 3-ethyl-1,4-hexadiene, 3-ethyl-1,5-hexadiene, 3,3-dimethyl-1,4-hexadiene, 3,3-dimethyl-1 , 5-hexadiene and the like. Among these, 5-ethylidene-2-norbornene is preferable from the viewpoint of availability and vulcanization speed of the resulting copolymer rubber.

  The ethylene-α-olefin-nonconjugated diene copolymer rubber of the present invention has an α-olefin content of 35 to 55% by weight, preferably 35 to 50% when the total of ethylene and α-olefin is 100% by weight. % By weight, more preferably 37-45% by weight. If the value of the α-olefin content is excessive, the heat resistance tends to decrease, and if it is too small, it becomes hard at low temperatures and the sealing performance becomes poor.

The Mooney viscosity (ML _{1 + 4} 121 ° C.) of the copolymer rubber is 135 to 170, preferably 140 to 165, and more preferably 145 to 160. When the ML viscosity is excessively large, the kneading properties are deteriorated, and when the ML viscosity is excessively small, the compression set and the shape retention are deteriorated.

  The unit derived from the non-conjugated diene in the copolymer rubber is 7 to 15% by weight, preferably 8 to 13% by weight, and more preferably 9 to 12% by weight. If the value of the non-conjugated diene content is too large, not only does the heat resistance tend to decrease, but the compression set value is not improved and the economy becomes inferior, and if it is too small, the compression set value is too low. Increase.

  In addition, the non-conjugated diene content ratio of the high molecular weight component and the low molecular weight component of the ethylene-α-olefin-nonconjugated diene copolymer rubber of the present invention is 0.9 to 1.1, and the high molecular weight component and the low molecular weight component It is preferable not to be biased to either of them. When the compression set value biased toward the low molecular weight side increases, the sealing performance becomes poor, and when it tends toward the high molecular weight side, the kneadability becomes poor. The ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by GPC of the copolymer rubber is 3.5 to 5.5, preferably 4.0 to 5.3. More preferably, it is 4.3 to 5.0. If the (Mw / Mn) ratio is excessive, the kneading characteristics and compression set are inferior, and if it is excessively small, the shape retention is deteriorated.

  The high molecular weight component of the ethylene-α-olefin-nonconjugated diene copolymer rubber of the present invention has an α-olefin content of 35 to 50% by weight when the total of ethylene and α-olefin is 100% by weight, rubber 100 The ML viscosity of the composition in which 70 parts by weight of paraffin oil is mixed with respect to parts by weight is 25 to 45, and the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by GPC is 3 .5 to 5.0.

The α-olefin content of the high molecular weight component of the present invention is such that the α-olefin content is 35 to 50% by weight, preferably 35 to 45% by weight, when the total of ethylene and α-olefin is 100% by weight. Preferably it is 37 to 42% by weight. When the weight ratio is excessively large, the molecular weight is difficult to increase and it becomes difficult to satisfy the claim requirements of the present invention, and when it is too small, the low temperature property is deteriorated. The molecular weight represented by ML viscosity of the high molecular weight component is 25 to 45 (ML _{1 + 4} , 125 ° C.) as ML viscosity of a composition in which 70 parts by weight of paraffin oil is mixed with 100 parts by weight of rubber, preferably 30 to 45, more preferably 35-45. If the molecular weight is too small, shape retention will be poor, while if the molecular weight is excessive, kneadability will be poor. The ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) measured by GPC of the high molecular weight component of the present invention is 3.5 to 5.0. When the molecular weight distribution is excessive, the kneading properties are deteriorated, and when the molecular weight distribution is excessively low, the shape retention is deteriorated.

  The low molecular weight component of the ethylene-α-olefin-nonconjugated diene copolymer rubber of the present invention is composed of ethylene, α-olefin, and nonconjugated diene monomer, and the total amount of ethylene and α-olefin is 100% by weight. An ethylene-α-olefin-nonconjugated diene copolymer rubber component having an α-olefin content of 40 to 60 wt.

  As the α-olefin, those described in the section of ethylene-α-olefin-nonconjugated diene copolymer rubber can be used. The α-olefin of the low molecular weight component and the α-olefin of the high molecular weight component may be the same or different.

  As the non-conjugated diene monomer, those described in the section of ethylene-α-olefin-non-conjugated diene copolymer rubber can be used. The low molecular weight component non-conjugated diene and the high molecular weight component non-conjugated diene may be the same or different.

  The ML viscosity of the low molecular weight component needs to be lower than the ML viscosity of the high molecular weight component. The weight ratio of the high molecular weight component to the low molecular weight component in the copolymer rubber (high molecular weight component weight / low molecular weight component weight) is preferably 1.5 / 1 to 3/1.

  If the high molecular weight component is excessive (low molecular weight component is low), the kneading property may be inferior. On the other hand, if the high molecular weight component is excessive (low molecular weight component is excessive), shape retention and compression set are deteriorated. It may be inferior.

  Examples of the method for obtaining the ethylene-α-olefin-nonconjugated diene copolymer of the present invention include the following methods.

  The method for producing the copolymer rubber of the present invention is not particularly limited, and can be obtained by polymerizing ethylene, α-olefin, and non-conjugated diene in the presence of a catalyst such as a so-called Ziegler-Natta catalyst or metallocene catalyst.

As a preferable polymerization method for carrying out the present invention, for example, solvent polymerization using an aliphatic hydrocarbon such as hexane, heptane, and octane as a solvent can be mentioned. The polymerization may be either continuous or batch. It is preferable to carry out by using two or more reactors connected in parallel or in series. Specifically, it is preferable that the following conditions (I) to (IV) are satisfied.
(I) It is solution polymerization (II) The polymerization temperature is 0 to 200 ° C. (III) The residence time is 5 to 120 minutes (IV) The polymerization tank pressure is normal pressure to 100 kg / cm ² G Within range

More preferably, a reactor for producing a low-temperature and low-pressure solution copolymer which performs polymerization under conditions of 30 to 160 ° C. and a polymerization pressure of 0 to 50 kg / cm ² G or less in which the polymer is dissolved using a solvent such as hexane. Therefore, it can manufacture efficiently.

  The ethylene-α-olefin-nonconjugated diene copolymer of the present invention has excellent shape retention and kneading processability of an extruded rubber, and is excellent in compression set value. Utilizing its excellent properties, it can be used in automotive materials, particularly seal sponge applications.

The present invention will be described based on examples.
Example 1
Hereinafter, although an example and a comparative example explain the present invention still in detail, the present invention is not limited to these.

[I] Preparation method of copolymer rubber
Copolymer rubber 1 ( copolymer rubber satisfying the conditions of the present invention)
Copolymerization of ethylene, propylene, and 5-ethylidene-2-norbornene was continuously performed using two 100 L SUS polymerizers equipped with stirring blades in series. That is, hexane was used as a polymerization solvent from the lower part of the first polymerization vessel at a rate of 86 kg / hour, and ethylene, propylene, and 5-ethylidene-2-norbornene were used as monomers at 2.65 kg / hour, 11.02 kg / hour, and. At a rate of 528 kg / hr, vanadium oxytrichloride, ethylaluminum sesquichloride, and ethanol are used as catalysts at a rate of 0.00195 kg / hr, 0.0109 kg / hr, and 0.00094 kg / hr, respectively, and hydrogen is used as a molecular weight regulator. Feeding continuously from the bottom of the polymerization vessel into the polymerization vessel at a rate of 7 NL / hour. On the other hand, the polymerization solution was continuously extracted from the upper portion of the polymerization vessel so that the polymerization solution in the polymerization vessel became 100 L. The polymerization solution withdrawn from the first polymerization vessel is supplied from the lower portion of the second polymerization vessel, and hexane as a polymerization solvent from the lower portion of the second polymerization vessel at a rate of 38 kg / hr, ethylene as a monomer, 5- Ethylidene-2-norbornene at a rate of 0.56 kg / hr and 0.20 kg / hr, respectively, and vanadium oxytrichloride, ethylaluminum sesquichloride, and ethanol as catalysts were 0.00276 kg / hr, 0.0155 kg / hr, and 0, respectively. Was continuously fed into the polymerization vessel at a rate of 001333 kg / hr. The copolymerization reaction was controlled at 44 ° C. for the first polymerization vessel and 45 ° C. for the second polymerization vessel by supplying low-pressure steam to a jacket attached to the outside of the polymerization vessel. A small amount of polypropylene glycol is added to the polymerization solution extracted from the polymerization vessel to stop the polymerization reaction, and after removing the monomer and washing with water, the solvent is removed with steam in a large amount of water, and the copolymer is taken out. It was dried under reduced pressure. By the above operation, ethylene-propylene-5-ethylidene-2-norbornene copolymer rubber was carried out at a rate of 4.2 kg / hour.

Copolymer rubber 2 and 3
According to each condition shown in Table 1, it was prepared in the same manner as copolymer rubber 1. However, the copolymer rubber 3 was polymerized using only one reactor instead of using two reactors connected in series.

[II] Method for measuring copolymer The properties of the polymer were measured by the following method.
(1) Propylene content Polypropylene, polyethylene, and an ethylene-propylene copolymer (50:50) were obtained by infrared absorption spectrum (IR spectrum) using an infrared spectrophotometer (IR-810 manufactured by JASCO Corporation). Measurement was performed using a standard product. The measurement sample was measured as a film of about 0.1 mm using a hot press machine. The measured values are in the order of literature values (characterized by polyethylene by infrared absorption spectrum, Takayama, Usami et al. Or Die Makromolekulare Chemie, 177, 461 (1976) Mc Rae, MA, Madam S, WF, etc.). The average of the values measured three times using the absorption peak (methyl branch) at 1155 cm ⁻¹ as a marker was used.

(2) Iodine value (5-ethylidene-2-norbornene, ENB)
The copolymer was hot-pressed to form a film with a thickness of 0.5 mm, and then the peak (wave number 1688 cm ⁻¹ ) transmittance derived from 5-ethylidene-2-norbornene was determined using an infrared spectrometer. The molar content of double bonds in the polymer was calculated and converted to iodine value.

(3) Molecular weight distribution (GPC)
This is carried out by gel permeation chromatograph (150C / GPC apparatus manufactured by Waters). The elution temperature is 140 ° C., the column used is Showa Denko K.K., Shodex Packed Column A-80M, the molecular weight standard material is polystyrene (for example, the molecular weight 68-8,400,000 made by Tosoh Corporation), and the polystyrene equivalent weight average molecule. Chain length (Aw), number average molecular chain length (An), and Z-average molecular chain length (Az) were obtained. As a measurement sample, about 5 mg of a polymer is dissolved in 5 ml of o-dichlorobenzene to a concentration of about 1 mg / ml. 400 μl of the obtained sample solution was injected, the elution solvent flow rate was 1.0 ml / min, and detection was performed with a refractive index detector.

[III] Evaluation method of kneading workability The copolymer rubber (20 parts oil-extended) prepared by the above method using a Toyo Seiki BR-600 mixer (0.6 L) and various compounding agents shown in Table 3 were kneaded. The time from ram lowering to the peak appearance of the dispersion process (BIT: Black Information Time) was examined. The ram pressure was 2 kg / cm ² ), the rotor speed was 50 rpm, the circulating oil temperature was 80 ° C., and the rubber kneading time was 30 seconds. Specific examples of BIT are, for example, “Rubber Test Method <New Version>”, Second Edition, Japan Rubber Association p. 176. Shown in

[VI] Sponge property evaluation (1) Preparation of composition 120 parts by weight of 20 parts of oil-extended copolymer rubber 1 shown in Table 1, 110 parts by weight of SRF-HS carbon (Asahi Carbon Co., Ltd., Asahi 50HG), paraffin 63 parts by weight of oil (Diana PS-430, manufactured by Idemitsu Kosan Co., Ltd.), 20 parts by weight of heavy calcium carbonate (NS-200, manufactured by Nitto Flour Chemical Co., Ltd.), 5 parts by weight of zinc oxide, and 1 part by weight of stearic acid. The mixture was kneaded at 60 rpm for 5 minutes using a 7 L Banbury mixer (BB-2 mixer manufactured by Kobe Steel). The obtained blended composition was cooled to room temperature and then wound around a 10 inch open roll whose temperature was adjusted to 40 ° C., and 2 parts by weight of calcium oxide (Vesta PP manufactured by Inoue Lime Co., Ltd.) per 100 parts by weight of copolymer, vulcanized 1.2 parts by weight of sulfur as an agent, 1.9 parts by weight of ethylenethiourea masterbatch (ETU-80 manufactured by Lane Chemie) as a vulcanization accelerator, and 2-mercaptobenzothiazole masterbatch (MBT-80 manufactured by Lane Chemie) 9 parts by weight, 1.0 part by weight of dipentamethylenethiuram tetrasulfide masterbatch (DPTT-70, Lane Chemie), 1.25 parts by weight of zinc di-n-butyldithiocarbamate (ZDBC-80, Lane Chemie), dimethyldithiocarbamine 0.5 parts by weight of zinc oxide (ZDMC-80 manufactured by Lane Chemie), p, '- oxybis (benzene sulfonyl hydrazide) (Sankyo Kasei Neoserubon # 1000) were mixed 2.7 parts by weight.
The blending compositions using the copolymer rubbers 2 and 3 were similarly adjusted except that the copolymers used were different.

(2) Vulcanization foaming The prepared composition was extruded into a cylindrical shape using a 45 mmφ extruder (L / D = 16), and continuously introduced into a hot air vulcanization tank adjusted to 230 ° C. did. The residence time in the hot air vulcanization tank was 5 minutes.
(3) Density The density of the foam obtained by vulcanization foaming was determined by an underwater substitution method.
(4) Tensile properties Test pieces were punched from a foam obtained by vulcanization foaming using a JIS No. 3 dumbbell and subjected to a tensile test. The tensile speed was 500 mm / min.
(5) Compression set The foam obtained by vulcanization foaming was held at 70 ° C. for 22 hours in a state compressed to 50% height. After a predetermined time, it was opened and the height after 30 minutes was measured to determine the compression set value.
Compression set (%) = 50 × [(original sample height) − (sample height after compression heat treatment)] / (original sample height)
(6) Shape retention The value obtained by dividing the height of the foam obtained by vulcanization foaming by the width was expressed in%.

＊１：５−エチリデン−２−ノルボルネン

* 1: 5-ethylidene-2-norbornene

Claims (3)

An ethylene-α-olefin-nonconjugated diene copolymer rubber containing the following high molecular weight component and low molecular weight component, wherein the α-olefin content is from 35 to 35 when the total of ethylene and α-olefin is 100% by weight. 55 wt%, Mooney viscosity (ML _{1 + 4} 121 ° C.) is 135 to 170, non-conjugated diene-derived units in the copolymer rubber are 7 to 15 wt%, and the weight of the high and low molecular weight components The ratio is 1.5 / 1 to 3/1, the non-conjugated diene content ratio of the high molecular weight component and the low molecular weight component is 0.9 to 1.1, the weight average molecular weight (Mw) and number average measured by GPC An ethylene-α-olefin-nonconjugated diene copolymer rubber having a molecular weight (Mn) ratio (Mw / Mn) of 3.5 to 5.5.
High molecular weight component: ML viscosity of a composition in which the α-olefin content is 35 to 50% by weight when the total of ethylene and α-olefin is 100% by weight, and 70 parts by weight of paraffin oil is mixed with 100 parts by weight of rubber. Is 25 to 45, and the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) measured by GPC is 3.5 to 5.0.
Low molecular weight component: α-olefin content is 40 to 60% by weight when the total of ethylene and α-olefin is 100% by weight The ethylene-α-olefin-nonconjugated diene copolymer rubber for sponge according to claim 1, wherein the nonconjugated diene is 5-ethylidene-2-norbornene. A rubber composition for a sponge obtained by adding 10 to 40 parts by weight of a plasticizer to 100 parts by weight of the ethylene-α-olefin-nonconjugated diene copolymer rubber according to claim 1.