JPH03188144A - Heat-resistant thermoplastic elastomer composition - Google Patents

Abstract

PURPOSE:To obtain the title composition excellent in heat aging resistance, mechanical strengths, oil resistance, weathering resistance, etc., by compounding a specified olefin thermoplastic elastomer composition with a 4-methylpentene-1 (co)polymer each in a specified amount. CONSTITUTION:A composition comprising 100 pts. wt. ethylene/alpha-olefin/ nonconjugated diene copolymer rubber (e.g. ethylene/propylene/ ethylidenenorbornene copolymer rubber), 5-200 pts.wt. crystalline PP resin (e.g. crystalline PP) and 0-300 pts.wt. mineral oil softener (e.g. paraffinic extender oil) is dynamically vulcanized with 0.5-15 pts.wt. reactive alkylphenol/ formaldehyde resin (e.g. dimethylol-p-octylphenol/formaldehyde resin) as a vulcanizer to obtain an olefinic thermoplastic elastomer composition in which the copolymer rubber is highly vulcanized. 100 pts.wt. said composition is mixed with 10-300 pts.wt. 4-methylpentene-1 homopolymer or copolymer of this monomer with an alpha-olefin to obtain the title composition.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is used for heat-resistant thermoplastic elastomer compositions, more specifically for automobile parts, industrial machine parts, etc., which have excellent heat resistance and high-temperature physical properties ( Regarding heat-resistant thermoplastic elastomers that require properties such as tensile properties, creep resistance, stress relaxation resistance, oil resistance, etc.), flexibility, high mechanical strength, shape recovery properties such as compression set, heat aging resistance, and weather resistance. .

(Prior art) Olefin thermoplastic elastomer compositions made of olefin rubber and crystalline polypropylene resin have excellent flexibility, heat aging resistance, weather resistance, mechanical properties, etc.
It is widely used in automobile parts, industrial machinery parts, etc. as a substitute for conventional rubber.

However, most conventional olefinic thermoplastic elastomer compositions are partially vulcanized olefinic rubber using organic peroxide as a vulcanizing agent, and have oil resistance and shape recovery properties at high temperatures (e.g. compression It could not be used as a high-performance material due to insufficient permanent deformation. moreover,
Vulcanization using organic peroxides has the disadvantage that it is difficult to improve the degree of vulcanization and mechanical strength is reduced because the polymer molecules are cleaved at the same time as vulcanization.

As a method to improve this drawback,
As shown in Japanese Patent Laid-Open No. 59-91142, a method is known in which a reactive alkylphenol formaldehyde resin (hereinafter referred to as a phenolic vulcanizing agent) is used as a vulcanizing agent. That is, in an olefinic thermoplastic elastomer composition consisting of a crystalline polypropylene resin and a vulcanized ethylene-α-olefin-nonconjugated diene copolymer rubber, a phenolic vulcanizing agent is used as the vulcanizing agent. As a result, this vulcanizing agent reacts selectively with the double bonds in the thermoplastic elastomer composition to perform vulcanization, preventing polymer chain scission during vulcanization and improving the degree of vulcanization. be able to. For this reason, a high degree of vulcanization that cannot be achieved with vulcanization systems using organic peroxides is possible, and oil resistance and shape recovery at high temperatures are significantly improved.

This allows it to replace synthetic rubbers such as chloroprene rubber, chlorosulfonated polyethylene rubber, ethylene-propylene-diene copolymer rubber, and acrylonitrile-butadiene copolymer rubber, which were conventionally used in fields requiring functionality. As a result, it has become possible to produce olefinic thermoplastic elastomer compositions that can be used in fields that require high functionality, such as automobile parts and industrial machine parts.

(Problems to be Solved by the Invention) Although the olefinic thermoplastic elastomer composition using a phenolic vulcanizing agent has high functionality, it is particularly used in the automobile field, as it has higher heat resistance and high-temperature physical properties (
For example, there are applications that require a maximum operating temperature of 170°C. In such a case, the crystalline polypropylene resin used in the olefin thermoplastic elastomer composition has insufficient heat resistance and cannot be used.

The object of the present invention is to provide a heat-resistant thermoplastic elastomer composition that can be used in applications requiring higher heat resistance and high-temperature physical properties.

(Means for Solving the Problems) The present invention achieves the above objects, and its gist is that 100 parts by weight of ethylene-α-olefin-nonconjugated diene copolymer rubber, crystalline polypropylene 5 to 200 parts by weight of resin and 0 to 300 parts of mineral oil softener
By dynamically vulcanizing the composition consisting of 0.5 to 15 parts by weight of a reactive alkylphenol formaldehyde resin as a vulcanizing agent, ethylene-α
・An olefin-based thermoplastic elastomer composition obtained by highly vulcanizing an olefin-nonconjugated diene copolymer rubber, and this olefin-based thermoplastic elastomer composition 100
The heat-resistant thermoplastic elastomer composition comprises 10 to 300 parts by weight of a homopolymer of 4-methylpentene-1 or a copolymer of 4-methylpentene-1 and an α-olefin.

The heat-resistant thermoplastic elastomer composition according to the present invention contains an ethylene-α-olefin-nonconjugated diene copolymer rubber as a first component. The α-olefin in the copolymer rubber is preferably one having 3 to 15 carbon atoms. As the non-conjugated diene, dicyclopentadiene, 1,4-hexadiene, ethylidene norbornene, methylidene norbornene, etc. are used.

In the present invention, propylene is suitable as the α-olefin, and ethylidenenorbornene is suitable as the non-conjugated diene, from the viewpoint of availability and vulcanization rate. Therefore, as a copolymer rubber, ethylene-propylene-
Ethylidene norbornene copolymer rubber is preferred.

The ethylene/α-olefin ratio in the copolymer rubber is 50150 to 90/10 by weight, more preferably 60/40.
~80/20 is suitable. The amount of non-conjugated diene is desirably in the range of 5 to 30, particularly 10 to 20, in terms of iodine value.

The heat-resistant thermoplastic elastomer composition according to the present invention is
A crystalline polypropylene resin is included as the second component.

As the crystalline polypropylene resin, a propylene homopolymer, a propylene-α/olefin random copolymer, or a propylene α/olefin block copolymer is used. As the α-olefin in these cases, ethylene, -butene, 1-pentene, 1-hexene, 4-methylpentene-1, etc. are used.

The crystalline polypropylene resin used in the present invention preferably has a melt flow rate (JIS K7210, 230°C, 1 load: 2.16 kg) of 0.1 to 50 (g/10 minutes). If the melt flow rate is less than 0.1, the fluidity of the resulting olefinic thermoplastic elastomer composition decreases, making it impossible to obtain a molded product with a good appearance. Moreover, when it is larger than 50, the mechanical strength of the thermoplastic elastomer composition obtained is significantly reduced. The preferred melt flow rate is 0.5-30, more preferably 0.8
~20.

In the present invention, the crystalline polypropylene resin is made of ethylene-α-olefin-nonconjugated diene copolymer rubber 10
0 parts by weight, 5 to 200 parts by weight, preferably 5 to 1 parts by weight
Add 50 parts by weight. If the amount added is less than 5 parts, the resulting heat-resistant thermoplastic elastomer composition will have poor fluidity, making it impossible to obtain a good molded product. On the other hand, if the amount exceeds 200 parts by weight, the effect of improving heat resistance will be small even if the 4-methylpentene-1 homopolymer or the copolymer of 4-methylpentene-1 and α-olefin is added.

The phenolic vulcanizing agent, that is, the reactive alkylphenol formaldehyde resin used in the present invention is represented by the following formula.

Here, n is an integer of 0-10, X is a hydroxyl group or a halogen group, and R is a saturated hydrocarbon group having 1 to 15 carbon atoms. This resin is commonly used as a vulcanizing agent for rubber, as described, for example, in US Pat. Nos. 3,287,440 and 3,709,840. This vulcanizing agent is obtained by polycondensation of a substituted phenol and an aldehyde in an alkaline medium.

The amount of the vulcanizing agent added needs to be 0.5 to 15 parts by weight per 100 parts by weight of the ethylene-α/olefin nonconjugated diene copolymer rubber. If the amount added is less than 0.5 parts by weight, the degree of vulcanization during dynamic vulcanization will be low, and the resulting heat-resistant thermoplastic elastomer composition will have poor oil resistance, shape recovery properties at high temperatures, and the like. Moreover, if the amount added is more than 15 parts, the flexibility of the resulting heat-resistant thermoplastic elastomer composition will be impaired. The amount of the vulcanizing agent added is preferably 1 to 10 parts by weight, more preferably 3 to 8 parts by weight.

Although the phenolic vulcanizing agent can be used alone, a vulcanization accelerator can be added to adjust the vulcanization rate.

As the vulcanization accelerator, metal halides such as stannous chloride and ferric chloride, and organic halides such as chlorinated polypropylene, butyl bromide rubber, and chloroprene rubber can be used. In this case, it is more preferable to add a metal oxide such as zinc oxide or magnesium oxide as a vulcanization accelerating aid.

To create the olefin-based thermoplastic elastomer composition used in the present invention, the first component, ethylene-α-olefin-nonconjugated diene copolymer rubber, is reacted in the presence of the second component, the crystalline polypropylene resin. Dynamic vulcanization may be performed using a type alkylphenol formaldehyde resin as a vulcanizing agent.

In the present invention, dynamic vulcanization refers to mixing the first component, ethylene-α-olefin-nonconjugated diene copolymer rubber, and the second component, crystalline polypropylene resin, and then kneading the mixture. - Vulcanization of α-olefin-nonconjugated diene copolymer rubber.

For this purpose, it is desirable to use the method described in Japanese Patent Publication No. 55-46138. That is, at a temperature higher than the temperature at which the engineered crystalline polypropylene resin melts into the crystalline polypropylene resin that is the second component (usually 160°
C to 250'C).

Thereafter, while continuing kneading, an alkylphenol vulcanizing agent is added and kneading is further continued to perform dynamic vulcanization. As the kneading device, a batch kneading device such as a Banbury mixer/heat roll or various types of Nigu, or a continuous kneading device such as a single screw extruder or a twin screw extruder can be used.

The ethylene-α/olefin-nonconjugated diene copolymer rubber, which is the first component contained in the olefinic thermoplastic elastomer composition used in the present invention, is highly vulcanized by dynamic vulcanization using a phenolic vulcanizing agent. Vulcanized. Here, the first component being highly vulcanized means unvulcanized ethylene extracted by hot xylene from the ethylene-α-olefin-nonconjugated diene copolymer rubber contained in the olefin-based thermoplastic elastomer composition. - means that the α-olefin-nonconjugated diene copolymer rubber is less than 5% by weight. In this way, since the degree of vulcanization is determined by the vulcanized ratio of ethylene-α-olefin-nonconjugated diene copolymer rubber in the olefinic thermoplastic elastomer, the components extracted by hot xylene are It is only necessary to consider the ethylene-α-olefin-non-conjugated diene copolymer rubber, and there is no need to consider components such as additives other than the ethylene-α-olefin-non-conjugated diene copolymer rubber. The thermal xylene extraction method will be explained in detail in the Examples section below.

Further, after dynamic vulcanization, a crystalline polypropylene resin can be further added.

In the present invention, in order to impart flexibility to the obtained olefin-based thermoplastic elastomer composition, a mineral oil-based softener may be added as necessary.

As the mineral oil-based softener that can be added, paraffin-based softeners are desirable from the viewpoint of taking advantage of the heat aging resistance and weather resistance, which are the characteristic properties of the resulting heat-resistant thermoplastic elastomer composition.

The mineral oil softener may be added in an amount of 3 parts by weight based on 100 parts by weight of ethylene-α/olefin non-conjugated diene copolymer rubber.
Add in an amount of 0.00 parts by weight or less. If more than 300 parts by weight is added, the mechanical properties will deteriorate and the mineral oil softener will ooze out, which is not preferred in practice.

This mineral oil softener may be included in the rubber in advance, or may be added during dynamic vulcanization, before or after dynamic vulcanization, or a combination of these may be used.

In the present invention, 4-methylpentene-1 is added to the obtained olefinic thermoplastic elastomer composition as a third component.
It is necessary to mix a homopolymer of or a copolymer of 4-methylpentene-1 and α-olefin. A homopolymer of 4-methylpentene-1 or a copolymer of 4-methylpentene-1 and an α-olefin is a crystalline olefin resin with a high melting point, and it can be polymerized using a Ziegler-Natsuta catalyst. be done. The α-olefins that can be used here include ethylene, propylene, 1-butene, 1-
Examples include hexene, 1-octene, 1-decene, I-tetradecene, and 1-octadecene. The molar ratio of 4-methylpentene-1 to these α-olefins is preferably 80/20 or more, preferably 85/15 or more.

Also, a homopolymer of 4-methylpentene-1, or 4-methylpentene-1
The melting point (Tm value recorded in ASTM D 3418) of the copolymer of methylpentene-1 and α-olefin is 200
"C or higher, preferably 230"C or higher is preferred. A copolymer of 4-methylpentene-1 and α-olefin having a melting point of 200° C. or lower is insufficient in improving heat resistance and high-temperature physical properties, which are the objectives of the present invention. Furthermore, the melt flow rate (260″C1 load 5 kg) of the homopolymer of 4-methylpentene-1 or the copolymer of 4-methylpentene-1 and α-olefin that can be used in the present invention is 0.5 to 8
0, preferably 1 to 35. If the melt flow rate is 0.5 or less, the resulting heat-resistant composition will have poor mechanical properties.

The content of the homopolymer of 4-methylpentene to 1 or the copolymer of 4-methylpentene-1 and α-olefin that can be added in the present invention is an olefin dynamically vulcanized using a phenolic vulcanizing agent. The amount is 10 to 300 parts by weight per 100 parts by weight of the thermoplastic elastomer composition. 4-
The amount of the homopolymer of methylpentene-1 or the copolymer of 4-methylpentene-1 and α-olefin is 1
If the amount is less than 0 parts by weight, the effect of improving the heat resistance of the resulting heat-resistant thermoplastic elastomer composition is insufficient, and if the amount is more than 300 parts by weight, it is a characteristic of the thermoplastic elastomer composition. Loss of flexibility.

Olefinic thermoplastic elastomer composition and 4-methylpentene-1 homopolymer, or 4-methylpentene-1
The homogenization of the α-olefin copolymer is carried out using a batch-type kneading device such as the Banbury Mixer 1 heating roll or various types of Nigu, or a continuous-type kneading device such as a single-screw extruder or a twin-screw extruder. 4-methylpentene-1 homopolymer or 4-methylpentene-1
It may be kneaded at a temperature higher than the melting point of the copolymer with α-olefin, or if a molding device with a kneading function such as an injection molding machine or an extrusion molding machine is used, olefin-based thermoplastic The elastomer composition and a homopolymer of 4-methylpentene-1 or a copolymer of 4-methylpentene-1 and an α-olefin are mixed in the form of small particles, and then a homopolymer of 4-methylpentene-1 is mixed. It may be formed at a temperature equal to or higher than the melting point of the copolymer of 4-methylpentene-1 and α-olefin.

The heat-resistant thermoplastic elastomer composition of the present invention can be used before and after dynamic vulcanization, or by combining an olefinic thermoplastic elastomer composition with a homopolymer of 4-methylpentene-1, or 4-methylpentene-1.
When homogenizing the copolymer of methylpentene-1 and α-olefin, commonly used auxiliaries such as fillers, antioxidants, copper inhibitors, colorants, ultraviolet inhibitors, and lubricants are added. Also good.

The heat-resistant thermoplastic elastomer composition obtained in the present invention can be molded into a desired molded product by ordinary injection molding, extrusion molding, blow molding, compression molding, etc., and has excellent heat resistance and high-temperature physical properties. It can be used for a wide range of applications such as required automobile parts and industrial parts.

(Effects of the Invention) The heat-resistant thermoplastic elastomer composition of the present invention exhibits the following particularly remarkable effects and has extremely great industrial utility value.

(1) The heat-resistant thermoplastic elastomer composition according to the present invention can be molded by a normal thermoplastic resin molding method, and good molded products can be easily obtained.

(2) The heat-resistant thermoplastic elastomer composition according to the present invention has excellent mechanical strength, shape recovery properties, oil resistance, heat aging resistance,
It has weather resistance, etc., and can be used for applications that require these properties.

(3) The heat-resistant thermoplastic elastomer composition of the present invention has greatly improved the heat resistance and high-temperature physical properties of conventional olefin-based thermoplastic elastomer compositions, so it is an automotive component that requires high heat resistance and high-temperature physical properties. It can be used for a wide range of applications such as , industrial parts, etc.

(Examples) Hereinafter, the present invention will be described in detail based on Examples, but the present invention is not limited to the following Examples unless it exceeds the gist thereof.

Measurement of physical properties in Examples was carried out by the following method.

(1) Hardness: ASTM D-2240 Tu0 meter A type.

(2) Tensile test...according to JIS K 6301, 2
Use a thick press sheet by punching it out with a No. 3 Danher.

Thereby, the values of tensile strength, elongation at break, and 100% modulus are measured.

(3) Oil resistance...according to JIS K 6301,
Using Nα3 test oil, 50mm x 25mm x 'l
Immerse the anal test piece and measure the change in weight. The soaking conditions were 70″c x 22 hours.

(4) Extraction amount of thermal xylene: The olefin thermoplastic elastomer composition is formed into a film having a thickness of 0.1 mm or less using a press.

Approximately 1.5 g of the film-like thermoplastic olefin elastomer composition is accurately weighed, and this weight is defined as wI. )
, and stirred for 30 minutes in 100 d of boiling xylene. The liquid is cooled to room temperature and filtered using a 0.3μ Teflon membrane filter.

The xylene in the filtrate is evaporated until the filtrate becomes about 5 cc and transferred to a centrifuge tube using 10-cyclohexane. Add 10 d of acetone and centrifuge at 110,000 rpm for 15 minutes. The supernatant liquid is removed and further washed with a solvent of cyclohexane/acetone=1/1 (volume ratio). Measure the weight after sufficiently evaporating the solvent. (
Let this weight be W2. ) The same operation is carried out on a crystalline propylene polymer (ie, the same crystalline polyprene polymer mixed with the ethylene-α.olefin-nonconjugated diene copolymer). (The weights corresponding to W+ and Wz are respectively W3 and W.) The weight percentage of the ethylene-α/olefin non-conjugated diene copolymer rubber in the olefin thermoplastic elastomer composition is W.

Let W be the weight percentage of the crystalline propylene polymer.

If the amount of hot xylene extracted is E(χ), then oil-extended ethylene-α olefin-nonconjugated diene copolymer rubber (ethylene-α olefin-nonconjugated diene copolymer rubber containing a mineral oil softener in advance) When using oil-extended ethylene-α-olefin-non-conjugated diene copolymer rubber, exclude the mineral oil-based softener in the oil-extended ethylene-α-olefin-non-conjugated diene copolymer rubber, and calculate the weight percentage of only the ethylene-α-olefin-non-conjugated diene copolymer rubber. Let be 6.

(5) Elastic modulus measurement/VISCOELASTICSPEC
The measurement is performed using TROMETERVES-11F3 (manufactured by Wakagi Seisakusho).

The sample is 5 am x 50 mm x 2 an, the distance between chucks is 30 mm, the frequency is 207, the amount of dynamic deformation is 0.01 mm, the temperature increase rate is 1°C/min, and the initial load is the cross-sectional area of the sample (anus) 10.2 g.

(Example 1) Melt flow rate is 5 (230°C12,16kg
), 60 parts by weight of crystalline propylene homopolymer, 100 parts by weight of ethylene-propylene-ethylidenenorporene copolymer rubber with an iodine value of 15, a Mooney viscosity ML of 92 (at 120°C), and a mineral oil-based softener. Paraffinic extension oil [kinematic viscosity 100 (@40°C)] 75 parts by weight,
Components consisting of 2 parts by weight of stannous chloride (SnCI□.6LO) and 2 parts by weight of zinc oxide were kneaded in a Banbury mixer with an internal volume of 31 at a rotor rotation speed of 15 Orpm. When the temperature of the kneaded material reached 170°C, 5 parts by weight of dimethylol-p-octylphenol-formaldehyde resin was added as a vulcanizing agent, and kneading was continued for an additional 3 minutes to obtain an olefin thermoplastic elastomer composition. . The thermal xylene extraction amount of the obtained olefinic thermoplastic elastomer composition was 2.2% by weight.

Obtained olefinic thermoplastic elastomer composition 10
0 parts by weight, melt flow rate 26 (260°C1
5kg), 4-methylpentene-1 homopolymer with a melting point of 240°C [TPX RT 18 manufactured by Mitsui Petrochemical Industries, Ltd.]
[Denoted as TPX (1?T18) in Table 1 below] 25 parts by weight was extruded and homogenized at 270°C using a co-directional twin-screw extruder.

Table 1 shows the physical properties of the obtained heat-resistant thermoplastic elastomer composition. FIG. 1 is a chart showing changes in storage modulus with respect to temperature changes in the thermoplastic elastomer compositions obtained in this Example, Example 2 and Comparative Example 1, which will be described later. It can be seen that the material has a sufficiently high storage modulus (and excellent heat resistance).

(Example 2) To 100 parts by weight of the olefinic thermoplastic elastomer composition obtained in the same manner as in Example 1, melt flow rate 26 (260°C, 5 kg) and melting point 4 to 235°C were added.
Methylpentene-1-α/olefin copolymer [TPX
MX 001 manufactured by Mitsui Petrochemical Industries, Ltd.] (denoted as TPX (MXOQI) in Table 1 below) 25 parts by weight was extruded using a co-directional twin-screw extruder under conditions of 270''C to homogenize.

Table 1 shows the physical properties of the obtained heat-resistant thermoplastic elastomer composition. It can be seen that the storage modulus at high temperature (170'c) is sufficiently high and the material has excellent heat resistance.

(Figure 1) (Comparative Example 1) Olefin thermal table obtained in the same manner as in Example 1 25 parts by weight of the polymer was heated to 210
It was extruded and homogenized under the conditions of °C.

Table 1 shows the physical properties of the thermoplastic elastomer composition obtained. It can be seen that the storage modulus at high temperature (170°C) is significantly lower than that at room temperature, indicating that high temperature use is not possible. (Figure 1) *1: Ethylene-propylene-ethylidene norbornene copolymer rubber, *2: Crystalline propylene homopolymer, *3: Paraffinic extender oil, *4: Phenolic vulcanized 7FL described in Example 1

[Brief explanation of drawings]

FIG. 1 shows Example 1 in the specification. Example 2 and comparative example 1
1 is a chart showing changes in storage modulus with respect to temperature changes measured for a thermoplastic elastomer composition, which is a product obtained by.

Claims (1)

[Claims] (1) 100 parts by weight of ethylene-α/olefin-nonconjugated diene copolymer rubber, 5 to 5 parts of crystalline polypropylene resin
By dynamically vulcanizing a composition consisting of 200 parts by weight and 0 to 300 parts by weight of a mineral oil softener using 0.5 to 15 parts by weight of a reactive alkylphenol formaldehyde resin as a vulcanizing agent, An olefinic thermoplastic elastomer composition prepared by highly vulcanizing an ethylene-α/olefin-nonconjugated diene copolymer rubber, and 4-methylpentene-1 per 100 parts by weight of the olefinic thermoplastic elastomer composition. Homopolymer or copolymer of 4-methylpentene-1 and α-olefin 10 to 3
00 parts by weight of a heat-resistant thermoplastic elastomer composition.