JPS60166339A - Thermoplastic elastomeric composition - Google Patents

Abstract

PURPOSE:The titled composition having extremely improved permanent compression set at high temperature, obtained by blending a hydrogenated derivative of a styrene-conjugated diene block copolymer with a softener for rubber, an olefin resin of peroxide decomposition type, and further conjugated diene rubber. CONSTITUTION:A blend comprising (A) 100pts.wt. hydrogenated derivative of a block copolymer shown by the formula (A is polymer block of monovinyl-substituted aromatic hydrocarbon, preferably styrene; B is elastomeric polymer block of conjugated diene, preferably butadiene, or isoprene; n is 1-5), (B) 80-300pts. wt. nonaromatic softener for rubber preferably mineral oil type of naphthene type or paraffin type, (C) 30-400pts.wt. olefin resin of peroxide decomposition type, (D) 0-900pts.wt. inorganic filler preferably talc, etc., and (E) 10-100pts.wt. conjugated rubber is kneaded, and 100pts.wt. of the composition is partially crosslinked with 0.1-3pts.wt. organic peroxide and 0.1-5pts.wt. crosslinking agent.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a novel thermoplastic elastomer material that is highly flexible, has excellent high-temperature compression set, mechanical strength, oil resistance, and moldability, and has less surface plating on the surface of molded products. The present invention relates to a composition.

In recent years, thermoplastic nystomers (hereinafter abbreviated as TPE), which are rubber-like soft materials that do not require a vulcanization process and have moldability similar to thermoplastic resins, have been used for automobile parts,
It is attracting attention in fields such as home appliance parts, wire coverings, medical parts, footwear, and miscellaneous goods.

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 use of vulcanized rubber, which is one of the wide application fields of rubber, and therefore, their use in the vulcanized rubber field is limited. For example, polyolefin TPK is a composite of a polyolefin resin as a hard segment and a polyolefin rubber as a soft segment by melt mixing, or one in which the rubber portion is crosslinked during this melt mixing. Although it is relatively inexpensive and has excellent heat resistance and weather resistance, it cannot be made soft, and even the most flexible one has a JIS-A hardness (JIS-6301) of about 70. J l5-A hardness of general vulcanized rubber: 50-7
It's still too hard compared to 0. In addition, polyolefin TP
The tensile strength of E in the low hardness region around JIS-A hardness 70 is 25 to 45 Kf/di, which is about 100 K of vulcanized rubber.
Kana is low compared to f/-. Furthermore, regarding compression set at high temperatures, which is required in many vulcanized rubber applications these days,
That of polyolefin TPE is about 55% at 100° C. for 22 hours, which is significantly inferior to about 40% of vulcanized rubber.

Polyester TPE and polyurethane TPE are also
Even the most flexible product on the market has a JIS-A hardness of 80.
~90, it is very hard compared to vulcanized rubber and is not suitable for the field of application of vulcanized rubber. Furthermore, polyester TPE is easily hydrolyzed and has poor hot water resistance, while polyurethane TPE
E has problems in moldability and heat resistance.

On the other hand, styrene-butadiene block copolymer (SBS
) and styrene-inprene block combination (SIS
) etc. are more flexible and have good rubber elasticity at room temperature than the other TPEs mentioned above, and the TPE compositions obtained from them have good moldability. It is excellent. However, since this polymer has a double bond as a conjugated diene block in its molecule, it has problems in heat aging resistance (thermal stability) and weather resistance.

By hydrogenating the intramolecular double bonds of a styrene and conjugated diene block copolymer, an elastomer with improved thermal stability can be obtained. In addition, several proposals have been made regarding TPE compositions using these hydrogenated derivatives, such as JP-A-50-14742 and JP-A-50-14742;
The specifications of various publications such as No. 6551 disclose TPE compositions in which a hydrogenated derivative of a styrene-conjugated diene block copolymer is blended with a rubber softener, an α-olefin polymer resin, and the like. However, TPE compositions using these hydrogenated derivatives have poor rubber elasticity at high temperatures (
Compression set) is poor.

In order to improve this point, the present inventors have already developed 0
) A crosslinkable composition obtained by silane-modifying a composition containing such a hydrogenated derivative and a crosslinked product thereof were proposed (Japanese Unexamined Patent Application Publication No. 1983-1999).
132032), and (2) in addition to the hydrogenated derivative of this styrene-conjugated diene block copolymer, a rubber softener, an α-olefin conjugated resin, and an inorganic filler, a peroxide-crosslinked olefin copolymer is also used. A method for producing a composition made of polymer rubber and in which this peroxide crosslinked olefin comb is crosslinked was proposed (Japanese Patent Laid-Open No. 59-6236). Furthermore, (3) a hydrogenated derivative of styrene-conjugated diene block copolymer, a rubber softener,
We proposed a partial crosslinking method using organic peroxide for a composition consisting of an α-olefin resin and an inorganic filler (
(Japanese Patent Application No. 58-6065).

However, the above proposal (11) has drawbacks such as the complexity of the process of changing the silane and post-crosslinking, and the loss of recyclability, which is one of the special features of TPg.

In addition, the proposal (2) above has a compression set (10
0°C 22 hours) with hardness (JIS-A) 60.
Another problem is that the ratio is still high at 0 to 55%, and the balance of oil resistance ratio, flexibility, strength, etc. may not be sufficient. However, the method proposed in L (3) is a simplified soaking method, and the molded product of the resulting nidistomer-like composition has less stickiness and less compression set at high temperatures (100°C
22 hours) had a hardness of +1j (JIS-A) 55 to 65 and a good fi of 45 to 48%.

On the other hand, the present inventors have further investigated crosslinking with organic peroxide in order to further improve the high temperature compression set of TPE compositions based on hydrogenated derivatives of styrene-diene block copolymer. In addition to hydrogenated derivatives of the styrene-conjugated diene block conjugate dt&, rubber softeners, and peroxide decomposition type olefin resins, conjugated dienes can be blended with rubber to significantly improve compression set at high temperatures! He discovered this and completed his discovery.

That is, the present invention is a thermoplastic elastomer composition comprising the following (a) to (e) and characterized in that it is partially crosslinked.

(a) General formula A+B A)n (where A is a polymer block of monovinyl-substituted aromatic hydrocarbon, B is an elastomeric aggregate block of conjugated diene, and n is an integer from 1 to 5.) Hydrogenated derivative of block copolymer represented by 100 parts (b) Softener for non-aromatic rubber 80 to 300 parts by weight (C) Peroxide decomposition type olefin resin 30 to 300 parts by weight
400 parts by weight (d) Inorganic filler 0 to 900 parts by weight (e) Conjugated diene rubber 10 to 10 parts by weight component (a) Component (a) used in the present invention has a general formula of A(-B-
A) It is a hydrogenated derivative obtained by hydrogenating a block copolymer represented by n, and in the above general formula, A is the polymer block of the monovinyl-substituted aromatic hydrocarbon layer, and B is the elastomer property of the conjugated diene. It is a polymer block, and n is an integer of 1 to 5.

The monovinyl-substituted aromatic hydrocarbon monomer constituting the polymer block A is preferably hastellene, α-methylstyrene, etc. The conjugated diene monomer in the polymer block B is preferably butadiene or isoprene. , or a mixture of both. When butadiene is used as a single conjugated diene monomer to form polymer block B, the block copolymer is hydrogenated to saturate the binary bonds. In order to maintain the diastereomeric strength after the polymerization, it is preferable to adopt polymerization conditions such that the 1,2-microgrooves in the microstructure of the polybutadiene block are 20 to 50%, more preferably 1,2-microgrooves. - The microstructure is of 35-45%.

The weight average molecular weight of polymer block A in the block copolymer is 5,000 to 125,000. Block B is 15000
The range is preferably from 250,000 to 250,000.

Many methods have been proposed for producing these block copolymers, but a typical method is, for example, the method described in Japanese Patent Publication No. 40-23798, using a lithium catalyst or Ziegler type. It can be obtained by block polymerization in an inert solvent using a catalyst.

The hydrogenation treatment of these block copolymers is carried out in an inert solvent by the method described in the specifications of Japanese Patent Publication No. 42-8704, Japanese Patent Publication No. 43-6636, or Japanese Patent Publication No. 46-20814. Hydrogenation is carried out in the presence of a hydrogenation catalyst.

In this hydrogenation, at least 50%, preferably 80% or more of the olefin-type bonds in the polymer block B are hydrogenated, and 25% or less of the aromatic unsaturated bonds in the polymer block are hydrogenated. be done. One such hydrogenated block copolymer is commercially available from Shell Chemical Company under the trade name "KRATON-GJ."

Component (b) The rubber softener used as component (b) in the present invention is:
Non-aromatic mineral oils or liquid or low molecular weight synthetic softeners are suitable. Mineral oil-based rubber softeners, called process oils or extender oils, are generally used to soften, increase the volume, and improve processability of rubber.
A mixture of naphthene rings and paraffin chains, with the number of carbon atoms in the paraffin chains accounting for 50% of all carbons.
Those occupying the above amount are called paraffinic, those with a naphthene carbon number of 30 to 45% are naphthenic, and those with more than 30% aromatic carbon are aromatic.

The mineral oil rubber softener used as component (b) of the present invention is preferably a naphthenic or paraffinic one in the above category, and an aromatic rubber softener having an aromatic carbon number of 30% or more The composition with (a) is unfavorable from the viewpoint of dispersibility. The properties of these non-aromatic rubber softeners include a kinematic viscosity of 20 to 500 cst at 37.8°C.
, pour point = 10~-15°C and flash point = 170~3
Indicates 00°C.

As the synthetic softener, polybutene, low molecular weight polybutadiene, etc. can be used, but the mineral oil-based softener for rubber gives better results.

The blending amount of the softener as component (b) is 80 to 300 parts by weight per 100 parts of component (a), preferably 1
50 to 250 genitalia. If the blend exceeds 300 parts by weight, the softener tends to bleed out and the final product may become sticky, and its mechanical properties may also be reduced. Further, if the amount is less than 80 parts by 1 part, there is no problem in practical use, but it is insufficient from an economic point of view and flexibility is also lost.

Component (e) The peroxide-decomposed olefin resin used as component (e) in the present invention is a resin that is thermally decomposed by heat treatment in the presence of peroxide to reduce the molecular weight and increase the fluidity of the resin. Refers to olefin-based resins, such as isotactic polypropylene and copolymers of propylene and a small amount of α-olefin, such as propylene-ethylene copolymers, propylene-1-butene copolymers, and propylene-1 copolymers. -hexene copolymer, propylene-4-methyl-1-pentene copolymer, and the like.

M of peroxide decomposition type olefin resin used
FR (ASTM-D-1238-L conditions, 230°C) is 0.1 to s o y/1o min, especially sail 5 to aor/l
A range of 0 minutes is preferable.

The blend f# of component (c) is 30 to 400 parts by weight per 100 parts by weight of component (a), and if the blend exceeds 400 parts by weight, the hardness of the resulting nidistomer-like composition increases. If it is too soft, flexibility is lost and a product with a rubbery feel cannot be obtained. A preferred blend is 50-300% liquid part.

Component (d) An inorganic filler may be added to the composition of the present invention as required. This inorganic filler not only has the benefit of reducing product costs as an extender, but also has a positive effect on quality improvement (compression set, etc.).

Examples of inorganic fillers include calcium carbonate, carbon black, talc, magnesium hydroxide, mica, clay, barium sulfate, natural silicic acid, synthetic silicic acid (white carbon), and titanium oxide. Examples of carbon black include channel black. , furnace black, etc. can be used. Among these inorganic fillers, talc, calcium carbonate and furnace black are economically advantageous and preferred.

The blending amount of the inorganic filler is 1 of the hydrogenated derivative of component (a).
The amount is from 0 to 900 parts by weight, preferably up to 500 parts by weight. If the amount exceeds 900 parts by weight, the mechanical strength of the composition will drop significantly, and the hardness will increase, resulting in a loss of flexibility, making it impossible to obtain a product with a rubbery feel.

Component (e) The conjugated diene rubber used as component (e) in the present invention is a natural or synthetic rubber that has high olefinic unsaturation and can usually be vulcanized with sulfur. Synthetic rubbers include imprene rubber, styrene-butadiene rubber,
Butadiene rubber, nitrile rubber, etc. are good. These are 2
More than one species can be used together.

The blending amount of component (e) is 10 to 100 parts by weight based on 10 parts by weight of component (a), and if it is less than 10 parts by weight, the compression set at high temperatures will be low. Moreover, if the amount exceeds 100 parts, the strength of the resulting elastomeric composition will be significantly reduced. A preferred blend is 20 to 60 parts by weight.

Manufacturing method The method for manufacturing the composition of the present invention consists of two steps. First, the first step is a step of kneading a mixture consisting of components (- to (e)).

The mixing method may be a method commonly used for rubber, plastics, etc., such as a -screw extruder, a twin-screw extruder, a roll, a Banbury mixer, or various kneaders.

The second step is a step of partially crosslinking the composition obtained in the first step by adding an organic peroxide, a crosslinking aid, and optionally an antioxidant. There is a method of kneading using an extruder or the like. Particularly when a Banbury mixer is used, there is an advantage that the first step and the second step can be carried out continuously.

Another example of a partial crosslinking method is a method in which peroxide is impregnated into a pellet-like composition consisting of each component obtained in the first step in hot water, and then the temperature is raised to statically partially crosslink ( For example, the specification of JP-A-56-98248)
There is.

The organic peroxide used in step @2 may be either aromatic or aliphatic, and may be a single peroxide or a mixture of two or more peroxides.

Specifically, 2,5-dimethyl-215y (benzoylperoxy)-hexane, t-butylperoxybenzoate, dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy) )-hexane, t
-Butylcumyl peroxide, diisopropylbenzohydroperoxide, 19. U-bis-(t-butylperoxyimprovil)-benzene, benzoyl peroxide, and the like are used.

However, as crosslinking aids that can be used in combination with the above-mentioned peroxides, there are acrylic polyfunctional monomers such as ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, trimethylolpropane triacrylate, etc., as well as divinylbenzene, liquid polybutadiene, etc. .

In addition, antioxidants that may be used in some cases include (1) monophenolic compounds, and (2) bis.

Tris or polyphenol compound, (3) thiobisphenol compound, and (4) phenol compound consisting of polyhydric phenol or its derivative, +5)
There are amine compounds such as +7 f cyamine compounds, +61 diphynylamine compounds, and (7) p-phenylenediamine compounds.

+1) Compounds belonging to monophenolic compounds include 2
．． 6-di-tert-butyl-p-cresol, 2,
6-tert-butylphenol, 2,4-dimethyl-6-tert-butylphenol, 2,4.6-1
-tert-butylphenol and the like.

(2) Bis, tris or polyphenol compounds include 4,4-dihydroxydiphenyl, 2,2'-methylenebis(4-ethyl-6-tert-butylphenol), tris(2-methyl-4-hydroxy-5- te
rt-butylphenyl)butane, tetrakis[methylene-3-(3'+5'-di-tert-butyl-4'-hydroxyphenyl)propionate]methane, and the like.

(3) Thiobisphenol compounds include 414'-thiobis(6-tert-butyl-3-methylphenol), 2,2'-thiobis(6-tert-butyl-4-
methylphenol), etc.

(4) Polyhydric phenols or derivatives thereof include
Examples include t-butylhydroquinone.

(5) Naphthylamine compounds include phenyl-α-naphthylamine.

(6) Diphenylamine compounds, such as p-impropoxydiphenylamine.

(7) p-phenylenediamine compounds include N, N'
-diphenyl-p-phenylenecyamine, N,N'-di-2-naphthyl-p-phenylenediamine, and the like.

Among them, the phenolic antioxidants (11, (2), fa) are preferred.

Organic peroxide used in the second step, crosslinking aid,
The amount of antioxidant is 100 parts by weight of the composition consisting of component values) to (e), and 0.1 to 3 parts by weight of organic peroxide (preferably o, i to 1 part by weight 1 fIS) as a crosslinking agent. agent o,
i to 5 parts by weight (preferably 0.1 to 3 parts by weight) antioxidant 3ii'1i parts or less (preferably from 1 part to F), but in reality components (a) to (e) It is determined by taking into consideration the blending ratio of and the degree of crosslinking that affects the quality of the nidistomer composition obtained. In addition, it is generally preferable to set the amount of the crosslinking aid to about 1 to 3 times the molar ratio of the organic peroxide.

The degree of crosslinking [wt%] of the partially crosslinked elastomeric composition obtained according to the present invention was determined by wrapping sample 12 in 80 mesh gold steel and extracting with boiling xylene for 10 minutes using a Soxhlet extractor. Sample 1f of residual solid content weight
Expressed as a percentage of

In the present invention, the preferred degree of crosslinking is in the range of 5 to 70% by weight in the above measured values, and if it is less than 5% by weight,
The resulting nidistomer composition had poor high-temperature compression set, oil resistance, and stickiness of molded products. Moreover, if it exceeds 70% by weight and 1%, moldability deteriorates and at the same time, tensile elongation decreases.

The preferred degree of crosslinking for poems is in the range of 10 to 60% by weight.

Applications and Uses The compositions of the present invention can also contain additives such as pigments, heat stabilizers, antioxidants, ultraviolet absorbers, etc., if desired, as is done for conventional resin compositions.

Furthermore, the composition of the present invention can be molded using a commonly used thermoplastic resin molding machine, and thermoplastic resin molding methods such as injection molding, extrusion molding, blow molding, and calendar molding can be applied. be.

The fields of use of the elastomeric composition of the present invention include various wire coatings (insulation, sheathing), and industrial parts such as home appliance parts and automobile parts.

Specific applications include various gaskets, flexible tubes, hose coverings, weather strips, bending harnesses, side bumpers, moldings, filler panels, lamp housings, wire cable coverings, air intake hoses, etc.

Examples In these examples and comparison columns, the test methods used for various evaluations are as follows.

(1) Hardness [-] JIS-ni-6301, A type.

(2) Tensile strength (V!4/J) and tensile elongation [%] J
IS-6301, the sample used was an injection sheet with a thickness of 2III11, and the test piece was No. 3 type.

(3) Compression set [%] JIS-6301, 100°C, 22 hours, 25% deformation.

(4) Oil resistance [%] JIS-6301, JIS No. 1 oil, 100°C, 7
Volume change rate at 0 hours.

(5) Injection moldability Injection molding machine: 5oz inline screw type.

Mold: 100. Xl 00. X2. Thick sheet injection pressure 5ooKf/i Injection temperature = 230℃ Mold temperature = 40℃ When injection molding is performed under the following conditions: 100X100X
2. Injection moldability was judged to be good if sheet molding of each simple thickness was possible, there was no delamination or deformation, and there were no flow marks that significantly deteriorated the appearance.

(6) Molded product stickiness Two sheets of each thickness of 100X100X2 obtained by the above injection molding were stacked, a load of IK4 was applied on top of them, and after leaving them at room temperature for 24 hours, the two sheets were taken out and the two sheets were stacked together. If no blocking was observed when the sheet was peeled off, it was judged that the stickiness was good.

(1) Component (a) KRATON-Gl 651 (Br
ookfield Viscosity: 20 wt 11% Tolue: y solution, 2000 cps, 77° F] (2) Component (b) Diana Process Oil PW-380 manufactured by Idemitsu Kosan Co., Ltd. [paraffinic, kinematic viscosity: 3 B 1.6 cst (40
℃)・30.10 cst (100℃), average molecular weight near 46, term analysis: CN = 27.0%・CP=7
3.0%] (3) Component (c) pp-i: Polypropylene resin MA4 manufactured by Mitsubishi Yuka Co., Ltd.
MFR (2ao℃) 5.0 f/10min, density o,
9 o sy, /cIl) PP-2: Propylene-ethylene copolymer resin manufactured by Mitsubishi Yuka Co., Ltd. Be 50 (MFR (230°C) 2.8 71
0 minutes, density 0.905t/-] PP-3: Propylene-ethylene copolymer resin 5P-X 980 manufactured by Mitsubishi Yuka Co., Ltd.
0 (MFR (230℃) 1.5 r/l 0 min, density 0.892f/-) (4) Component (d) Surface treated with higher fatty acid ester, average particle size 2゜5
Micron calcium carbonate (5) component (e) DP-1: Nihon Gosei Rubber Co., Ltd. cis 1,4-polyinprene lR2200 (cis 1,4: 98 (%), Mooney viscosity ML1+4 (100°C) 82) DP -2:
Styrene-butadiene rubber 5BR150 manufactured by Japan Synthetic Rubber Co., Ltd.
2 (bonded styrene 23.5 (phrase, Mooney viscosity ML
1+4 (100°C) 52] (6) Organic peroxide pot: Niper B [benzoyl peroxide] manufactured by NOF Corporation PO-2: Perhexa 2,5B [2,5-
Dimethyl-2,5-di(t-butylperoxy)hexane-3] (7) Crosslinking aid CA-1 Nidivinylbenzene CA-2: Trimethylolpropane triacrylate (8) Antioxidant AO-1: Ciba Geigy Manufactured by Irganox 1010 (
Tetrakis [methylene-3-(3',5'-te
rt-butyl-4'-hydroxyphenyl) flobionate comethane) AO-2: Iruuchi Shinko Kagaku Kogyo Co., Ltd. Tsukrak White (
N,N'-di-2-naphthyl-p-phenylenediamine] In Example Example 1, as component (a), 100 parts by weight of KR
ATON-G 1e 51 and as component (b), 19
0 stitches of PW-380 were mixed in advance for about 5 minutes in a Henschel mixer, then polypropylene MA4 and Be2C were mixed as component (e) with 24 stitches each, and as component (d), 150 weight 40 parts by weight of calcium carbonate and 40 parts by weight of pulverized IR2200 as component (e) were added, mixed for about 1 minute, and blended at 200°C in a 40 mm diameter single screw extruder. The mixture ioo heavy liquid part contains 0.3 parts by weight of organic peroxide (NaI<-B), 0.9+tt part of crosslinking agent (divinylbenzene), and antioxidant (Irganox 10).
10) Add 0.2 layers and mix, then 30. The reaction was carried out at 200° C. in a twin-screw extruder with a diameter of 1.5 mm to obtain a partially crosslinked thermoplastic nidistomer pellet.

This was injection molded and evaluated.

The obtained molded product had a hardness of 58, little decrease in strength and elongation, a compression set of 39%, oil resistance (22%), and a good balance of physical properties such as flatness.

Furthermore, Examples 2 and 3 were manufactured by the same method as Example 1, and the compositions and evaluation results are as shown in Table 1.

As for quality, compression set, oil resistance, injection moldability, stickiness, etc. were all well balanced compared to Comparative Examples 1 to 5 below.

Comparative Example 1 has the same hardness as Example 1, and has the same hardness as Example 1.
It was blended in a 30+m diameter twin-screw extruder according to the formulation shown in the table, and was not crosslinked.

Comparative Examples 2 and 3 are formulations corresponding to Examples 1 and 3, respectively, with component (e) removed. In addition, in Comparative Examples 4 and 5, component (e) was 1OfJili
Less than 1 part hexagram and more than 100 i, lj, i back.

(Bottom margin)

Claims (1)

[Claims] (a) General formula % formula % (where A is a polymer block of monovinyl-substituted aromatic hydrocarbon, B is an elastomeric polymer block of conjugated diene, and n is 1 to 5 (b) 80 to 300 parts by weight of a non-aromatic rubber softener; (C) 30 to 300 parts by weight of a peroxide-decomposed olefin resin; 4
1.00 parts by weight, (d) 0 to 900 parts by weight of an inorganic filler, and (e) 10 to 100 parts by weight of a conjugated diene rubber, and is partially crosslinked.