JPH0463851A - Thermoplastic elastomer composition - Google Patents

Abstract

PURPOSE:To obtain a thermoplastic elastomer composition excellent in oil resistance and hue stability and desirable for automobile components requiring high performances, etc., by adding a specified resin, a mineral oil softener and a phenolic resin vulcanizer to an ethylene/alpha-olefin/nonconjugated copolymer rubber. CONSTITUTION:A thermoplastic elastomer composition is prepared by dynamically vulcanizing a composition comprising 100 pts.wt. ethylene/alpha-olefin/ nonconjugated diene copolymer rubber, 10-300 pts.wt., desirably 20-200 pts.wt. crystalline olefin resin (most suitably having a melt flow rate of 0.8-20), and 10-300 pts.wt. mineral oil softener containing 20wt.% or above hydrogenated paraffinic mineral oil (%CA<0.5, and an iodine value of 0.5% or below) with a reactive alkyl phenol/formaldehyde resin as a vulcanizer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermoplastic elastomer composition, and more specifically, it is suitably used for automobile parts, industrial machine parts, etc. that require high functionality, and in particular, This invention relates to a thermoplastic elastomer composition with improved oil resistance and hue stability.

[Conventional technology]

Olefin thermoplastic elastomer compositions made of olefin rubber and crystalline olefin resin are excellent in flexibility, heat aging resistance, weather resistance, and the like.

However, most conventional olefinic thermoplastic elastomer compositions are partially vulcanized using organic peroxides, and lack oil resistance and shape recovery properties at high temperatures (e.g., compression set). This makes it difficult to use it as a high-performance material.

Furthermore, vulcanization using organic peroxides causes crosslinking and molecular scission of the crystalline olefin resin at the same time as vulcanization of the olefin rubber, making it difficult to achieve a high degree of vulcanization, and also impairing the mechanical properties of the resulting composition. It also has the disadvantage of being inferior.

As a method to improve this drawback, the Japanese Patent Publication No. 584613
As shown in No. 8 and Japanese Patent Publication No. 59-91142, a method using a reactive alkylphenol formaldehyde resin (hereinafter abbreviated as "phenolic vulcanizing agent") as a vulcanizing agent is known. .

That is, the above method uses a phenolic vulcanizing agent as a vulcanizing agent to produce ethylene-α olefin-
This method improves the degree of vulcanization by selectively reacting only the double bonds in the non-conjugated diene copolymer rubber. According to this method, it is possible to achieve a high level of vulcanization that cannot be achieved with vulcanization systems using organic peroxides, and the resulting composition has significantly improved oil resistance and shape recovery properties at high temperatures. Become something.

As a result, olefin-based thermoplastic elastomer compositions have traditionally been used in fields requiring functionality such as chloroprene rubber, chlorsphonated polyethylene rubber, ethylene-propylene-diene copolymer rubber,
It has become possible to use it mainly as a substitute for synthetic rubbers such as acrylonitrile butadiene copolymer rubber, and in fields where high functionality is required, such as automobile parts and industrial machinery parts.

[Problem to be solved by the invention]

However, olefinic thermoplastic elastomer compositions using phenolic vulcanizing agents have insufficient fluidity;
It has a disadvantage of poor moldability such as injection moldability and extrusion moldability.

As an effective means for improving fluidity, there is a method of adding a mineral oil-based softener to an olefin-based thermoplastic elastomer composition using a phenolic vulcanizing agent.

However, since general mineral oil-based softeners contain components containing carbon-carbon double bonds, the phenolic vulcanizing agent reacts with the carbon-carbon double bonds in the mineral oil-based softener. consumed.

Therefore, in order to achieve a sufficient degree of vulcanization and ensure good oil resistance, there is a problem in that an expensive phenolic vulcanizing agent must be used more than necessary.

On the other hand, phenolic vulcanizing agents are incompatible with olefin combs and crystalline olefin resins, so using them more than necessary may lead to a decrease in the mechanical properties of the thermoplastic elastomer composition and the generation of foreign matter. , leading to poor appearance of molded products.

Furthermore, general mineral oil-based softeners are prone to discoloration due to light or heat due to the double bonds mentioned above, and because of this,
Olefin-based thermoplastic elastomer compositions containing common mineral oil-based softeners have a drawback of poor hue stability.

The present invention aims to solve these problems and provide an olefinic thermoplastic elastomer composition having excellent physical properties.

[Means to solve the problem]

In order to achieve the above object, the present inventor has conducted various studies on olefinic thermoplastic elastomer compositions that are highly vulcanized using phenolic vulcanizing agents, and has found that mineral oil-based softeners with specific physical properties. Through selective use, the basic properties of olefinic thermoplastic elastomers such as excellent flexibility, heat aging resistance, and weather resistance are not impaired, and the use of phenolic vulcanizing agents improves mechanical properties, oil resistance, and high temperature properties. The present invention was completed based on the finding that a composition with particularly improved hue stability can be obtained while fully exhibiting the effect of improving shape recovery properties described below.

That is, the gist of the present invention is as follows: 100 parts by weight of ethylene-α/olefin-nonconjugated diene copolymer rubber, 10 to 300 parts by weight of crystalline olefin resin, 10 parts by weight of mineral oil softener.
By dynamically vulcanizing a composition consisting of ~300 parts by weight using 0.5 to 15 parts by weight of a reactive alkylphenol formaldehyde resin as a vulcanizing agent, an ethylene-α-olefin-nonconjugated diene was obtained. An olefinic thermoplastic elastomer composition made by highly vulcanizing copolymer rubber, wherein the mineral oil softener is paraffinic mineral oil containing 20% by weight or more of hydrogenated paraffinic mineral oil. A special plastic elastomer composition characterized by:

The present invention will be explained in detail below.

The 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 has 3 to 1 carbon atoms.
5 is suitable. Examples of the non-conjugated diene include dicyclopentadiene, 1,4-hexadiene, ethylidene norbornene, and methylidene norbornene. In the present invention, from the viewpoint of availability and vulcanization speed,
Propylene is suitable as the α-olefin, and ethylidene norbornene is suitable as the non-conjugated diene. Therefore,
Ethylene-propylene-ethylidene norbornene copolymer rubber is suitable as the copolymer rubber.

The weight ratio of ethylene/α-olefin in the copolymer rubber is in the range of 50150 to 90/10, preferably 60/40.
~80/20 range. The amount of non-conjugated diene in the copolymer rubber is 5 to 30, especially 1 in terms of iodine value.
A range of 0 to 20 is desirable.

The thermoplastic elastomer composition according to the present invention contains a crystalline olefin resin as a second component.

Crystalline olefin resins include ethylene, propylene, 1
Homopolymers of olefins such as -butene, ■-pentene, l-hexene, and 4-methylpentene-1, copolymers using two or more of these olefins, and mixtures thereof are used. . Among these crystalline olefin resins, crystalline propylene resins are most suitable for reasons such as easy availability and good performance/price ratio. Specifically, propylene homopolymer, propylene-α/olefin random copolymer, propylene α/
Examples include olefin block copolymers.

For example, when a crystalline polypropylene resin is used as the crystalline olefin resin used in the present invention, the melt flow rate (JIS K7210.230°C1
The load (2.16 kg) is preferably in the range of 0.1 to 50 (g/10 minutes). If the resin has a melt flow rate lower than 0, the fluidity of the resulting composition will decrease,
It is difficult to obtain a molded article with a good appearance, and in the case of a resin larger than 50, the resulting composition does not have sufficient mechanical strength. The melt flow rate is preferably in the range of 0.5 to 30, more preferably in the range of 0.8 to 20.

In the present invention, the crystalline olefin resin is added in an amount of 10 to 300 parts by weight, preferably 20 to 2 parts by weight, per 100 parts by weight of ethylene-α/olefin-nonconjugated diene copolymer rubber.
Use in a range of 0.00 parts by weight.

If the amount of copolymer rubber used is less than 10 parts by weight,
The fluidity of the resulting composition is poor, and a molded product with a good appearance cannot be obtained, and if the amount is more than 300 parts by weight, the hardness of the resulting composition is too high, resulting in poor flexibility, which is a characteristic of thermoplastic elastomers. Missing.

In the present invention, a mineral oil-based softener is used to improve the fluidity of the olefin-based thermoplastic elastomer composition. Paraffinic mineral oil containing 20% by weight or more of paraffinic mineral oil (abbreviated as "paraffinic mineral oil") is used. As a result, the present invention can provide a thermoplastic elastomer composition that allows effective vulcanization, further improves oil resistance, and improves hue stability.

In the present invention, paraffinic mineral oil refers to ASTM
D 3238 means a mineral oil with a %C1 of 60 or more. If a mineral oil with a %C3 of less than 60 is used, the resulting composition will not have sufficient weather resistance or heat aging resistance, and even if it contains hydrogenated paraffinic mineral oil, the degree of crosslinking will not be improved. , the effect of improving color fastness is not sufficient.

Hydrogenated paraffinic mineral oil is obtained by hydrogenating paraffinic mineral oil by a conventional method. Particularly preferred is paraffinic mineral oil obtained by hydrogenating ordinary paraffinic mineral oil using a catalyst such as nickel or tungsten, followed by distillation and dewaxing, and then secondary hydrogenation treatment.

Hydrogenated paraffinic mineral oil is produced by the above hydrogenation treatment.
%CA according to STM D 3238 is 0°5 or less,
Preferably, the amount of iodination is 0.5% or less. Hydrogenated (rough-in) mineral oil that satisfies these performance values is
The effect of improving oil resistance and hue stability of the composition is remarkable.

It is essential that the content of the hydrogenated paraffinic mineral oil in the paraffinic mineral oil is 20% by weight or more.

When the content is less than 20% by weight, even if hydrogenated paraffinic mineral oil is contained, the effect of improving oil resistance and the effect of improving hue stability of the resulting composition will be insufficient. These effects become more remarkable as the content of hydrogenated paraffinic mineral oil in paraffinic mineral oil increases. Therefore, the greatest effect is obtained when a paraffinic mineral oil consisting essentially of only hydrogenated (rough) mineral oil is used as the paraffinic mineral oil.

The kinematic viscosity (at, 40°
C) is preferably in the range of 20 to 1500 centistokes. If the kinematic viscosity of the mineral oil is lower than 20 centistokes, the mineral oil oozes out or volatilizes during processing. In addition, the kinematic viscosity of mineral oil is 1500
If it is higher than centistokes, the copolymer rubber will be dispersed non-uniformly.

Hydrogenated paraffinic mineral oil and normal paraffinic mineral oil may be mixed with their respective kinematic viscosities within this range, or may be mixed with substances outside this range and adjusted within this range. good.

Paraffinic mineral oil containing 20% by weight or more of hydrogenated paraffinic mineral oil is 10 to 30% by weight per 100 parts by weight of ethylene-α-olefin-nonconjugated diene copolymer rubber.
Use within the range of 0 parts by weight.

If the proportion used is less than 10 parts by weight, there will be no effect of improving the fluidity of the resulting composition, and if it is greater than 300 parts by weight, the mechanical properties of the resulting composition will deteriorate and mineral oil will ooze out. Practically unfavorable.

The mineral oil may be included in the copolymer rubber in advance, or may be added during dynamic vulcanization, before or after dynamic vulcanization, or a combination of these treatments may be used. good. For example, by pre-containing hydrogenated paraffinic mineral oil in the copolymer rubber, during dynamic vulcanization, or before and after dynamic vulcanization,
Ordinary paraffinic mineral oil may be added, or
A mixture of hydrogenated paraffinic mineral oil and normal paraffinic mineral oil in a predetermined ratio may be used, or
Only hydrogenated paraffinic mineral oil may be used. However, in view of the gist of the present invention, it is preferred that only hydrogenated paraffinic mineral oil be contained in the copolymer rubber before dynamic vulcanization.

The phenolic vulcanizing agent used in the present invention is a substance represented by the following formula.

Here, n is an integer of 0 to 10, X is a hydroxyl group or a halogen atom, and R is a saturated hydrocarbon group having 1 to 15 carbon atoms.

The above materials are commonly used as vulcanizing agents for rubber, as described, for example, in US Pat. No. 3,287,440 and US Pat. No. 3,709,840. This vulcanizing agent is obtained by condensation polymerization of a substituted phenol and an aldehyde in an alkaline medium.

The amount of the vulcanizing agent used is in the range of 0.5 to 15 parts by weight per 100 parts by weight of the ethylene-α/olefin nonconjugated diene copolymer rubber. If the amount of the vulcanizing agent used is less than 0.5 parts by weight, the degree of vulcanization during dynamic vulcanization will be low, and the resulting composition will not have sufficient oil resistance, shape recovery properties at high temperatures, etc. If the amount is more than 1 part by weight, the flexibility of the resulting composition will be impaired. The preferred amount of the vulcanizing agent used is in the range of 1-10 parts by weight, more preferably 3-8 parts by weight, per 100 parts by weight of the copolymer rubber.

The vulcanizing agent can be used alone, but it can also be used in combination with a vulcanization accelerator in order 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. When a vulcanization accelerator is used together, it is more preferable to use a metal oxide such as zinc oxide.

In the present invention, dynamic vulcanization refers to mixing ethylene-α olefin-nonconjugated diene copolymer rubber as the first component and crystalline olefin resin as the second component, and while kneading the ethylene-α olefin-nonconjugated diene copolymer rubber. - Means vulcanization of 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, an ethylene α/olefin-nonconjugated diene copolymer rubber and a mineral softener are added to a crystalline olefin resin (the mineral softener can be added at an appropriate stage as described above), and usually a crystalline olefin is added. Temperature higher than the melting temperature of the resin (for example, 1 for crystalline polypropylene resin)
Mix at a temperature of 70°C or higher). Thereafter, while continuing kneading, an alkylphenol vulcanizing agent is added and kneading is further continued to perform dynamic vulcanization.

As a kneading device, a batch mixing device such as Banbury mixer 1 heating roll or various kneaders, or
A continuous kneading device such as a single screw extruder or a twin screw extruder can be used.

In the present invention, by the above dynamic vulcanization, ethylene-
The α-olefin-nonconjugated diene copolymer rubber is highly vulcanized. Here, highly vulcanized refers to unvulcanized ethylene-α, which is extracted with hot xylene from the ethylene-α-olefin-nonconjugated diene copolymer rubber contained in the obtained thermoplastic elastomer composition. It means that the amount of olefin-nonconjugated diene copolymer rubber is less than 5% by weight.

Note that the components extracted by this hot xylene are focused only on the ethylene-α-olefin-non-conjugated diene copolymer rubber, and include components such as additives other than the ethylene-α-olefin-non-conjugated diene copolymer rubber. shall not be taken into consideration.

In the present invention, a crystalline olefin resin can be further added after dynamic vulcanization. In addition, a filler is used before and after dynamic vulcanization, or when adding the above-mentioned crystalline olefin resin for homogenization.

Processing aids such as antioxidants, copper inhibitors, colorants, ultraviolet inhibitors, and lubricants may be added.

The thermoplastic elastomer composition according to the present invention can be
The desired molded product can be formed using injection molding, extrusion molding, blow molding, compression molding, etc., and the molded product can be used for various widths such as automobile parts and industrial parts that require oil resistance and color stability. Can be suitably used in a wide range of applications.

〔Example〕

Hereinafter, the present invention will be explained in more detail based on Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

Measurement of physical properties in Examples was carried out by the following method. Table 1 shows the physical properties of the paraffinic mineral oil used, and Table 2 shows the results of measuring the physical properties of the resulting composition.

(1) Hardness: Based on ASTM D-2240, durometer A
Type used.

(2) Tensile test In accordance with JIS K6301, a 2 mm thick press sheet was punched out using a No. 3 dumbbell.

(3) Oil resistance Based on JIS K6301, using No. 3 test oil, a test piece measuring 50 mm x 25 mm x 2 cylinders was immersed and weight changes were measured. Immersion conditions are 70'CX22
It was time.

(4) Amount of thermal xylene extraction The olefin thermoplastic elastomer composition is formed into a film of 0.1 mm or less using a press.

Approximately 1.5 g of the olefinic thermoplastic elastomer composition is accurately weighed (this weight is referred to as Wl), placed in 1'00 boiling xylene, and stirred for 30 minutes.

The liquid is cooled to room temperature and filtered using a 0.3μ Teflon membrane filter.

Evaporate the xylene in the filtrate until the filtrate becomes approximately 5 cc and transfer to a centrifuge tube using 107 nl of cyclohexane. Add acetone 10m/15 at 10000RPM
Centrifuge for 1 minute. The supernatant liquid is removed and further washed with a solvent of cyclohexane/acetone = 1/1.

Measure the weight after sufficiently evaporating the solvent.

(This weight is designated as W2) The same operation as above is performed for the crystalline propylene polymer. (W, , the weight corresponding to W2 is W3
．． W4) The weight percentage of the ethylene-α-olefin-nonconjugated diene copolymer rubber in the olefin thermoplastic elastomer composition is Wo, and the weight percentage of the crystalline propylene polymer is W.

The thermal xylene extraction amount E (%) is calculated by the following formula.

However, when using oil-extended ethylene-α olefin-nonconjugated diene copolymer rubber (ethylene-α olefin-nonconjugated diene copolymer rubber containing paraffinic mineral oil in advance), oil-extended The paraffinic mineral oil in the ethylene-α-olefin-nonconjugated diene copolymer rubber is excluded, and W is the weight percentage of only the ethylene-α-olefin-nonconjugated diene copolymer rubber.

(5) Hue stability The obtained thermoplastic elastomer composition was used in a super long life weather meter (WEL-3UN-HCH-B).
-EM, manufactured by Suga Test Instruments ■) for 100 hours at a black panel temperature of 68°C.

The hue of the treated thermoplastic elastomer composition is measured using an 8M color computer (SM-4, manufactured by Suga Test Instruments ■). The hue of the untreated thermoplastic elastomer composition is also measured. Hue stability is evaluated based on the size of the color difference (ΔE).

Example 1 Melt flow rate is 5 (230°C 12, 16 kg)
60 parts by weight of crystalline propylene homopolymer (PP),
Iodine number 15, Mooney viscosity ML, +.

(120°C) 100 parts by weight of 92 ethylene-propylene-ethylidene norbornene copolymer rubber (EPDM),
Components consisting of 100 parts by weight of hydrogenated paraffinic mineral oil (A in Table 1), 2 parts by weight of stannous chloride (3-neck Cn2.6 H2O), and 2 parts by weight of zinc oxide were placed in a Banbury mixer with an internal volume of 31 cm. - at rotor rotation speed of 150 RPM
It was mixed with

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.
A thermoplastic elastomer composition was obtained.

Example 2 In Example 1, 5 parts by weight of hydrogenated paraffinic mineral oil (A in Table 1) was used instead of 100 parts by weight of hydrogenated paraffinic mineral oil.
0 parts by weight and hydrogenated paraffinic mineral oil (B in Table 1) 50
A thermoplastic elastomer composition was obtained in the same manner as in Example 1, except that part by weight of the mixed oil was used.

Example 3 In Example 1, instead of 100 parts by weight of hydrogenated paraffinic mineral oil, 3 parts by weight of hydrogenated paraffinic mineral oil (A in Table 1)
A thermoplastic elastomer composition was obtained in the same manner as in Example 1, except that a mixed oil of 0 parts by weight and 70 parts by weight of paraffinic mineral oil (B in Table 1) was used.

Comparative Example 1 In Example 1, 100 parts by weight of hydrogenated paraffinic mineral oil was replaced with 1 part by weight of hydrogenated paraffinic mineral oil (A in Table I).
A thermoplastic elastomer composition was obtained in the same manner as in Example 1, except that a mixed oil of 0 parts by weight and 90 parts by weight of paraffinic mineral oil (B in Table 1) was used.

Comparative Example 2 A thermoplastic elastomer was prepared in the same manner as in Example 1, except that 100 parts by weight of paraffinic mineral oil (B in Table 1) was used instead of 100 parts by weight of hydrogenated paraffinic mineral oil. A composition was obtained.

As is clear from the results of physical property measurements shown in Table 2, the thermoplastic elastomer composition according to the present invention is particularly improved in terms of oil resistance and dye stability.

〔Effect of the invention〕

The thermoplastic elastomer composition according to the present invention has the following properties and has extremely high industrial utility value.

(1) The thermoplastic elastomer composition according to the present invention can be molded by a normal thermoplastic resin molding method, and a molded article with a good appearance can be easily obtained.

(2) The plastic elastomer composition according to the present invention is excellent in flexibility, heat aging resistance, weather resistance, mechanical properties, shape recovery properties, especially oil resistance and hue stability, and meets these performance requirements. It can be suitably used for various purposes.

Applicant: Mitsubishi Monsanto Chemicals Co., Ltd. Agent: Patent Attorney Oka 1) Kazuhiko Table-2

Claims (2)

[Claims] (1) 100 parts by weight of ethylene-α/olefin-nonconjugated diene copolymer rubber, 10 to 3 parts of crystalline olefin resin
00 parts by weight and 10 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 obtained by dynamically vulcanizing an ethylene-α-olefin-nonconjugated diene copolymer rubber, in which the mineral oil softener is hydrogenated. 20% paraffinic mineral oil
A thermoplastic elastomer composition characterized in that it contains paraffinic mineral oil in an amount of at least % by weight. (2) Hydrogenated paraffinic mineral oil is %C_A0
．． The thermoplastic elastomer composition according to claim 1, wherein the thermoplastic elastomer composition has an iodine value of 5% or less and an iodine value of 0.5% or less.