JPH01193352A - Thermoplastic elastomer composition - Google Patents

Abstract

PURPOSE:To obtain the title composition suitable for automobile parts, parts of household electric appliances, etc., having excellent rubber elasticity, flexibility, heat resistance, etc., by blending a hydrogenated derivative of styrene- butadiene block copolymer with a specific amount of a softener for rubber, etc. CONSTITUTION:100 pts.wt. sum of (A) 30-70wt.%, preferably 35-60wt.% hydrogenated derivative of styrene-butadiene block copolymer and (B) 70-30wt.%, preferably 65-40wt.% softener for rubber (preferably mineral oil base or synthetic resin base) is blended with (C) 20-150 pts.wt., preferably 30-100 pts.wt. polyester elastomer. A component A wherein >=80wt.% double bond of olefinic type in the polybutadiene block and <=25wt.% aromatic unsaturated bond in the polystyrene block are-hydrogenated is preferable as the component A.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is directed to a thermoplastic elastomer (hereinafter referred to as rTP) which has excellent rubber elasticity, flexibility, heat resistance, ozone resistance, and moldability.
(abbreviated as EJ).

In recent years, rubber-like soft materials that do not require a vulcanization process,
TPE, which has moldability similar to that of thermoplastic resins, is attracting attention in fields such as automobile parts, home appliance parts, medical equipment, food equipment parts, electric wires, and miscellaneous goods.

[Conventional technology]

Currently, various types of TPE such as polyolefin, polyurethane, polyester, and polystyrene have been developed and are commercially available.

However, these TPEs do not reach the level of vulcanized rubber in terms of quality in the application of vulcanized rubber, which is one of the wide application fields of rubber, and therefore, their use in the field of vulcanized rubber is limited. The reality is that it is extremely limited.

For example, polyolefin TPE is relatively cheap and has excellent heat resistance and weather resistance, but it is inferior in flexibility. It has the disadvantage that it is still too hard compared to the hardness of vulcanized rubber, which is 60.

Similarly, polyester TPE and polyurethane TPE
JTS-A hardness is 70~ even for commercially available medium weight and flexible ones.
It is hard and has a hardness of about 90, making it unsuitable for use as vulcanized rubber.

In addition, styrene-butadiene-styrene-pro-7 polymer (SBS) and styrene-isoprene-styrene (
S I S) Polystyrene-based TP such as block polymer
E has superior flexibility compared to the above-mentioned TPE, but because it has a double bond in the polybutadiene block or polyisoprene block in the polymer, it has poor heat aging resistance (thermal stability), weather resistance, and There is a problem with ozone resistance.

For example, as a blend of styrene elastomer and polyester elastomer, S
A method using BS or SIS was introduced in Japanese Patent Application Laid-Open No. 50-82162, but these did not have sufficient performance in terms of ozone resistance, thermal stability, etc.

On the other hand, it is well known that a block copolymer with improved thermal stability can be obtained by hydrogenating the intramolecular double bonds of a block copolymer of styrene and a conjugated diene. So-called styrene-based TPE, which uses such a block copolymer as a rubber component and blends it with polyolefin resin, oil, filler, etc., has superior flexibility and workability compared to olefin-based TPE. However, it is still inferior to vulcanized rubber in terms of rubber elasticity.

Note that "rubber elasticity" here refers to a property that has as few inflection points as possible, such as the yield point, especially in tensile properties, and has a high modulus (e.g., 300%) compared to conventional TPE at a certain hardness. This means that the stress during elongation is high).

In other words, TPE having such characteristics exhibits rubber elasticity close to that of vulcanized rubber.

[Problem to be solved by the invention]

The present inventors have conducted extensive studies to develop a TPE that is excellent in flexibility and rubber elasticity, and has good heat resistance, ozone resistance, and moldability.

[Means to solve the problem]

As a result, by blending a hydrogenated derivative of a styrene-butadiene block copolymer, a rubber softener, and a polyester elastomer, they found that it was soft and completed the present invention.

That is, in the present invention, for a total of 100 parts by weight of 30 to 70% by weight of a hydrogenated derivative of a styrene-butadiene block copolymer as component A and 70 to 30% by weight of a rubber softener as component B, , is a thermoplastic elastomer characterized by containing 20 to 150 parts by weight of a polyester elastomer as component C.

The above-mentioned component A used in the present invention has the general formula %) [However, in the formula, A is a monovinyl-substituted aromatic hydrocarbon polymer block, B is a conjugated diene elastomeric polymer block, and n is an integer from 1 to 5] and is a hydrogenated derivative of a block copolymer.

Although various monovinyl-substituted aromatic hydrocarbon monomers constituting the polymer block A may be used, styrene and α-methylstyrene are particularly preferred. Also,
The conjugated diene monomer of polymer block B is preferably butadiene or isoprene, and a mixture of both may be used. When butadiene is used as a single conjugated diene monomer to form polymer block B, the 1,2-microstructure in the microstructure in the polybutadiene is 20 to 50% in order to maintain elastomeric properties. It is preferable to adopt polymerization conditions such that 1,2-microstructure is 35 to 45%. The proportion of polymer block B in the copolymer is preferably at least 65% by weight.

The average molecular weight of the above polymer block A is from 5000.
125,000, block B from 15,000 to 25,000
It is preferably in the range of 0.

Many methods have been proposed as methods for producing hydrogenated derivatives of block copolymers having the above general formula, but typical methods include, for example, Japanese Patent Publication No. 42-8704;
There is a method described in Publication No. 3-6636 and the like.

In the hydrogenation during its production, at least 50%, preferably 80% or more of the olefinic double bonds in polymer block B are hydrogenated, and not more than 25% of the aromatic unsaturated bonds in polymer block A. is preferably hydrogenated. As such a block polymer, a commercially available polymer such as rKRATON-GJ (trade name manufactured by Shell Chemical Company) can be used.

As the rubber softener of component B that can be used in the present invention, mineral oil-based or synthetic resin-based softeners are suitable.

Mineral oil-based softeners are a combination mixture of aromatic rings, naphthenic rings, and paraffin chains, and those in which the paraffin chain carbon number accounts for 50% or more of the total carbons are called paraffinic softeners. Those containing 30 to 45% aromatic carbon are called naphthenic, and those containing more than 30% aromatic carbon are called aromatic. Among these,
Mineral oil-based softeners preferred as component B of the present invention are naphthenic and paraffinic softeners, and have an aromatic carbon number of 30%.
These are as follows. Aromatic compounds are not very preferable from the viewpoint of dispersion with the component A used in the present invention.

In terms of properties, the kinematic viscosity at 37.8°C is 20 to 500 cst,
Pour point is -10~-15℃ and flash point (COC) is 1
It is something like 70-300°C.

As the synthetic resin softener, polybutene, low molecular weight polybutadiene, etc. can be used, but mineral oil softeners are preferred.

The polyester elastomer of component C used in the present invention includes: (1) a block copolymer consisting of an aromatic polyester block (a) and a non-aromatic polyester block (bl), (2) a block copolymer consisting of an aromatic polyester block (a) and a polyester There are block copolymers consisting of an ether block (C), (2) block copolymers consisting of an aromatic polyester block (al, and the blocks (b) and (C) described above).

The aromatic polyester block (a) is a polyester oligomer having a structure in which an aromatic dicarboxylic acid and a diol are condensed, and examples thereof include polyethylene terephthalate oligomer, polypropylene terephthalate oligomer, polytetramethylene terephthalate oligomer, polypentamethylene terephthalate oligomer, etc. .

A non-aromatic polyester block (BL) is a polyester synthesized from (1) a polyester oligomer in which an aliphatic or alicyclic dicarboxylic acid and an aliphatic diol are condensed, (2) an aliphatic lactone or an aliphatic monool carboxylic acid. An example of the former (1) is 1.
Alicyclic dicarboxylic acids such as 4-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, and dicyclohexyl-4,4'-dicarboxylic acid, or aliphatic dicarboxylic acids such as succinic acid, oxalic acid, adipic acid, and sebacic acid. Examples include polyester oligomers having a structure in which one or more of these are condensed with one or more of diols such as ethylene glycol, propylene glycol, tetramethylene glycol, and pentamethylene glycol, and the latter (2)
Examples include polycaprolactone-based polyester oligomers synthesized from ε-caprolactone, ω-oxycaproic acid, and the like.

As the polyether block (C), for example, polyether
(Alkylene oxide) glycol and other polyether oligomers having an average molecular weight of about 400 to about 6,000 are mentioned. Here, poly(alkylene oxide) glycol includes polyethylene glycol, poly(1,
2 and 1.3 propylene oxide) glycol, poly (tetramethylene oxide) glycol, poly (hexamethylene oxide) glycol, block or random copolymers of ethylene oxide and propylene oxide, block or random copolymers of ethylene oxide and tetrahydrofuran, etc. Can be mentioned.

The polyester elastomer (component C) can be produced by first synthesizing oligomer blocks consisting of the components, and then condensing the blocks with ester bonds, or by using another method. As a method, for example, a method may be used in which block Tbl is first polymerized and then further mixed with the component monomer of block (a) and condensed.

Examples of such polyester elastomers include commercially available polymers such as "Pelprene P" and "SJ
(product name manufactured by Toyobo Co., Ltd.) and ``Hytrel'' (product name manufactured by Toshi DuPont).

The blending ratio of each component constituting the TPE of the present invention is component A
is 30 to 70% by weight based on the total amount of component A and component B,
Preferably from 35 to 60% by weight.

If the amount is less than 30% by weight, the rubber elasticity and heat resistance of the resulting TPE will be poor, and if it exceeds 70% by weight, the flexibility and moldability will be poor. In addition, component B is also 70 to 30% by weight,
Preferably 65-40% by weight. If it exceeds 70% by weight, rubber elasticity and heat resistance will be poor, and if it is less than 30% by weight, flexibility and moldability will deteriorate. Also, component C is component A
and component B in a total amount of 20 to 150 parts by weight, preferably 30 to 100 parts by weight. If it is less than 20 parts by weight, moldability will be poor, and if it exceeds 150 parts by weight, flexibility will be lost.

In the present invention, when obtaining TPE, polymers other than these essential components such as polymers containing these essential components, styrene polymers, etc., or additional components such as inorganic fillers such as calcium carbonate, talc, mica, and carbon black are added. be able to. Furthermore, additives such as antioxidants, ultraviolet absorbers, slip agents, fluidity improvers (polyethylene wax, etc.) can be added according to the target quality. In addition, a compatibilizer (for example, maleated polyolefin, etc.) may be used to further enhance the compatibilization of component A and component C.
can also be blended.

The method for manufacturing the TPE of the present invention can be by mechanical melt-kneading. Specifically, a general melt kneading machine such as a Banbury mixer 1, various kneaders, 1 axle, or a twin-screw extruder can be used.

Moreover, thermoplastic resin molding methods such as injection molding, extrusion molding, and blow molding can be applied to the TPE of the present invention.

The TPE of the present invention can be used for household appliances, industrial parts such as automobile parts, food packaging materials, medical equipment parts, daily miscellaneous goods, and the like.

〔Example〕

The test methods used for various evaluations in the examples are as follows. However, all measurement samples were made using a 5-ounce in-line screw type injection molding machine at an injection pressure of 500 kg/
ctA, an injection speed of 220°C, and a mold temperature of 40°C, by transverse punching of a 2fl thick sheet.

1) JIS-A hardness (-) JIS-63
01 (21300% stress (kg/ad) JIS-
Ni-6301 (3) Compression set [%] JIS-6301 (70°C x 22 hours) (4) Ozone resistance JIS-630150
pphm, 20% elongation, 40°C, 500 hours, evaluated by the presence or absence of cracks (5) Molding processability A 120sn x 80 baking soda x 2x thick injection molded sheet obtained under the above molding conditions was used for short shots. The molding processability was evaluated as good when there were no defects and the appearance (flow marks, delamination) was extremely bad.

Moreover, each compounding component used in the example is as follows.

(1) Component A: Hydrogenated derivative of styrene-butadiene block copolymer is manufactured by Shell Chemical Company [
RATON-G 1651 j (Brookfie
ld viscosity: 2000 cps in 20% by weight toluene solution,
77°F).

(2) Component B: As a rubber softener, R manufactured by Idemitsu Kosan Co., Ltd.
PW380J (40℃ kinematic viscosity 381.6 cSt)
was used.

(3) Component C: As a polyester elastomer,
The following 3M class 'Pelprene' (polyester ether elastomer) manufactured by Toyobo Co., Ltd. was used.

■P-30B (JIS-A hardness 70(-), crystal melting point 160('C)) ■P-70B (JIS-A hardness 96(-), crystal melting point 200[''C)) ■P~150B ( JIS-A hardness 98 (-), crystal melting point 212 ('C)) (4) Others: The following two components were used.

■Olefin resin; polypropylene resin ([Mitsubishi Polypro BC5CJ, MFR5g/lo min) ■Styrene-butadiene block copolymer; manufactured by Shell Chemical Co., Ltd. [Califlex TR-1102J (Brookfield viscosity;
12000 cps in 25% by weight toluene solution.

77°F) Experimental Examples In addition to the formulation shown in Table 1, the phenolic antioxidant "Irganox 1010" was added to 100 parts by weight of the mixture.
Add 0.1 part by weight of J, L/D33, cylinder diameter 4
Melt and knead with a 5-Ryu twin-screw extruder at a setting of 220°C to form TP.
E. Pele got 21. Using this pellet, a sheet having a thickness of two fins was molded by injection molding as described above. Table 1 shows the results of various evaluations made using the obtained sheet.

In addition, as can be seen from Figure 1, compared to the comparative example, the example has higher stress at the same hardness, a smaller yield point shape, and has a more linear stress elongation and good rubber elasticity. This shows that.

(The following is a blank space) [Effects of the invention] The thermoplastic elastomer of the present invention has flexibility, rubber elasticity,
Since it has an excellent quality balance of heat resistance, ozone resistance, and moldability, it can be applied to a wide range of fields of use.

[Brief explanation of the drawing]

FIG. 1 is a drawing showing the tensile properties of Example 1 and Comparative Example 2. Curve A is an example, and curve B is a comparative example. Patent applicant: Mitsubishi Yuka Co., Ltd. Agent: Patent attorney Masashi Hasemoto Hisamoto agent: Patent attorney Takaya Yama

Claims (1)

[Scope of Claims] Component A: 30 to 70% by weight of a hydrogenated derivative of a styrene-butadiene block copolymer, and Component B: a rubber softener of 70 to 30% by weight, for a total of 100 parts by weight, and Component C: a polyester elastomer. A thermoplastic elastomer composition comprising 20 to 150 parts by weight.