JPH07292209A - Elastomer composition excellent in blow moldability - Google Patents

Abstract

PURPOSE:To obtain a thermoplastic elastomer compsn. excellent in blow moldability and also in flexibility, heat resistance, weatherability, and strengths by compounding a specific hydrogenated block copolymer with a propylene resin and a hydrocarbon oil. CONSTITUTION:This thermoplastic elastomer compsn. is prepd. by compounding 100 pts.wt. hydrogenated block copolymer component with 10-80 pts.wt. polyolefin resin having a melt flow rate of 0.1-4.5g/10min and 20-100 pts.wt. hydrocarbon oil. The copolymer component is a mixture of two hydrogenated block copolymers each comprising at least two polymer blocks (A) consisting mainly of arom. vinyl compd. units and at least one polymer block (B) consisting mainly of conjugated diene units and comprises 50-90 pts.wt. hydrogenated block copolymer having a content of polymer block A of 12-24wt.% and a number average mol.wt. of 45,000-95,000 and 10-50 pts.wt. hydrogenated block copolymer having a content of polymer block A of 28-38wt.% and a number average mol.wt. of 100,000-200,000.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic elastomer composition, which is particularly excellent in hollow moldability, flexibility, heat resistance,
The present invention relates to a thermoplastic elastomer composition having excellent weather resistance and strength.

[0002]

2. Description of the Related Art Conventionally, vulcanized rubber has been mainly used for automobile parts, home electric appliance parts, medical parts, and miscellaneous goods. In particular, styrene-based thermoplastic elastomers such as styrene / butadiene block copolymers and styrene / isoprene block copolymers are excellent in flexibility and low temperature characteristics,
Further, since it has a tensile-stress characteristic close to that of the vulcanized rubber, it can be suitably used as a substitute for the vulcanized rubber. However, the above-mentioned styrene-based thermoplastic elastomer has a problem that its use is limited because the weather resistance and heat aging resistance are not sufficient.

Therefore, several proposals have been made regarding an elastomer composition using a hydrogenated derivative (hereinafter abbreviated as a hydrogenated block copolymer) obtained by improving the above styrene-based thermoplastic elastomer. For example, Japanese Patent Laid-Open No. 4
JP-A 1-2909 discloses an elastomer composition in which an olefin polymer is mixed with a hydrogenated block copolymer having a specific structure. Further, JP-A-52-65551 discloses an elastomer composition in which a hydrogenated block copolymer having a specific structure is blended with an olefin polymer and a hydrocarbon oil. These elastomer compositions are characterized by excellent weather resistance and heat aging characteristics. However, although these compositions are preferably used for injection and extrusion molding, their blow moldability was not always sufficient.

Therefore, some proposals have been made regarding hydrogenated block copolymer compositions having excellent blow moldability. For example, JP-A-54-88950 discloses a composition of a hydrogenated block copolymer having a specific structure and a polypropylene resin for the purpose of improving blow moldability and polyethylene.
A composition comprising a processing aid selected from an ethylene-vinyl acetate copolymer and an ethylene-propylene copolymer has been proposed. However, since the above-mentioned processing aid has a low effect as a softening agent, it has a problem that only a hard molded product can be obtained as a result.

Similarly, JP-A-60-71656 proposes a hydrogenated block copolymer composition which is excellent in blow moldability, but ethylene-acrylate copolymer and ethylene- Since a vinyl ester copolymer is used, and this processing aid also has a low effect as a softening agent, there is a problem that only a hard molded product can be obtained as a result.

[0006]

Therefore, it is desired to improve the above-mentioned problems of the prior art and to develop a low-hardness elastomer composition having excellent flexibility, heat resistance, weather resistance, strength, and blow moldability. The current situation is that it is rare. An object of the present invention is to provide a novel elastomer composition which meets the demand.

[0007]

As a result of research, the inventors of the present invention have found that by blending a hydrogenated block copolymer having a specific structure with a specific propylene-based resin, and further combining a hydrocarbon oil, The present inventors have completed the present invention by discovering the surprising fact that a low-hardness elastomer composition having excellent properties, heat resistance, weather resistance, strength, and blow moldability can be obtained.

That is, according to the present invention, a block copolymer comprising a polymer block A containing at least two vinyl aromatic compounds as a main component and a polymer block B containing at least one conjugated diene compound as a main component is hydrogenated. In the composition containing the added block copolymer, (a) 100 parts by weight of the block copolymer mixture having the following composition, (a-1) the number average molecular weight is 45,000 to 95,000, and the polymer block A is The hydrogenated block copolymer constituting 12 to 24% by weight of the copolymer: 50 to 90 parts by weight (a-2) The number average molecular weight is 100,000 to 200,000.
And the polymer block A constitutes 28 to 38% by weight of the copolymer, the hydrogenated block copolymer: 10 to 5
0 parts by weight (b) Polyolefin resin having a melt flow rate of 0.1 to 4.5 g / 10 min: 10 to 80 parts by weight (C) Hydrocarbon oil 20 to 100 parts by weight Flexibility, heat resistance and weather resistance A low-hardness elastomer composition having excellent properties and strength and excellent blow moldability is provided.

The hydrogenated block copolymer used as the component (a) in the present invention comprises a polymer block A containing at least two vinyl aromatic compounds as a main component and at least 1
A block copolymer obtained by hydrogenating a block copolymer composed of a polymer block B mainly composed of individual conjugated diene compounds, for example, A-B-A, B-A-B-A, A- B-A-B-A, B
-A-B-A-B, (A-B) _4- Si, (B-A-
B) ₄ -Si, (AB) _4- Sn, (BAB) ₄
-Has a structure such as Sn.

The structure of the hydrogenated block copolymer which is particularly suitable for obtaining a molded article having excellent flexibility and processability and little anisotropy has a structure mainly composed of a conjugated diene compound at at least one polymerization end. A structure obtained by hydrogenating a block copolymer having a united block B, for example, B-
A-B-A, B-A-B-A-B, (B-A-B) _4-
Si, (B-A-B) ₃ (A-B) -Si, (B-A-
B) ₂ (A-B) _2- Si, (B-A-B) (A-B)
_3- Si, (B-A-B) _3- Si-R, (B-A-
B) ₂ -Si-R, R ', (B-A-B) _4- Sn,
(B-A-B) _2- Sn-R, a hydrogenated block copolymer having a structure such as R '(wherein R and R'are C ₁
An alkyl group -C ₈ R, R'may be the same or different).

Further, the polymer block A mainly containing vinyl aromatic compound and the polymer block B mainly containing conjugated diene compound have a distribution of vinyl aromatic compound or conjugated diene compound in each polymer block. It may be random or tapered (in which the monomer component increases or decreases along the molecular chain), partially block-like or any combination thereof, and when each of the polymer blocks B is two or more, The polymer blocks may have the same structure or different structures. As used herein, the expression "based on" means that the monomer units in question are at least 50% by weight of the polymer block, preferably at least 70%.
Means to occupy the above.

As the vinyl aromatic compound constituting the block copolymer of the present invention, for example, one or more selected from styrene, α-methylstyrene, vinyltoluene, p-tert-butylstyrene and the like. Of these, styrene is preferred.

As the conjugated diene compound, for example, butadiene, isoprene, 1,3-pentadiene, 2,3
One or more of dimethyl-1,3-butadiene can be selected, and among them, butadiene, isoprene and combinations thereof are preferable. The polymer block B mainly composed of the conjugated diene compound before hydrogenation can have a microstructure in the block arbitrarily selected. For example, in the case of a polybutadiene block, a 1,2-vinyl bond structure is used. Is 20 to 50% by weight, preferably 25 to 45% by weight, and the polyisoprene block has 80% by weight of 1,4-vinyl bond.
The above content is preferably 90% by weight or more.

In the present invention, the hydrogenated block copolymer is
Two types of (a-1) and (a-2) are used. The hydrogenated block copolymer (a-1) has a number average molecular weight of 45.
000 to 95,000, and the polymer block A constitutes 12 to 24% by weight of the copolymer. When the number average molecular weight of the hydrogenated block copolymer is less than 45,000, the strength and heat resistance of the elastomer composition decrease, the melt viscosity of the elastomer composition decreases, and drawdown occurs during blow molding, which is not preferable. On the other hand, when the number average molecular weight of the hydrogenated block copolymer exceeds 95,000, the melt elongation of the elastomer composition is lowered and the blow ratio is lowered, which is not preferable. Further, when the polymer block A is less than 12% by weight of the copolymer, the strength and heat resistance of the elastomer composition are deteriorated, which is not preferable. On the other hand, when the polymer block A exceeds 24% by weight of the copolymer, the flexibility of the elastomer composition decreases, which is not preferable.

The hydrogenated block copolymer (a-2) has a number average molecular weight of 100,000 to 200,000, and the polymer block A constitutes 28 to 38% by weight of the copolymer.
If the number average molecular weight of the hydrogenated block copolymer is less than 100,000, the strength and heat resistance of the elastomer composition will decrease, which is not preferable. On the other hand, if the number average molecular weight of the hydrogenated block copolymer exceeds 200,000, the melt elongation of the elastomer composition is lowered and the blow ratio is lowered, which is not preferable. Further, if the polymer block A is less than 28% by weight of the copolymer, the strength and heat resistance of the elastomer composition decrease, which is not preferable. On the other hand, if the polymer block A exceeds 38% by weight of the copolymer, the flexibility of the elastomer composition decreases, which is not preferable.

The molecular weight distribution of the hydrogenated block copolymers (a-1) and (a-2) [ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) (Mw / Mn)] is 5 or less,
It is preferably 2 or less, more preferably 1.5 or less. When the molecular weight distribution exceeds 5, the strength and heat resistance of the elastomer composition are not sufficient, which is not preferable.

The mixing ratio of the block copolymer (a-1) and the block copolymer (a-2) is such that the total amount of the block copolymer is 100 parts by weight.
1) 50 to 90 parts by weight, block copolymer (a-2)
Is 10 to 50 parts by weight. Block copolymer (a-
When 1) is less than 50 parts by weight, the melt elongation of the elastomer composition is lowered and the blow ratio is lowered, which is not preferable. When the block copolymer (a-1) exceeds 90 parts by weight, the strength and heat resistance of the elastomer composition decrease, the melt viscosity of the elastomer composition decreases, and drawdown occurs during blow molding, which is not preferable.

These block copolymers are not limited as long as they have the above-mentioned structure, and the production method thereof is not limited. For example, a lithium catalyst can be prepared by the method described in Japanese Patent Publication No. 40-23798. It can be used to synthesize a vinyl aromatic compound-conjugated diene compound block copolymer in an inert solvent.

A method for producing a vinyl aromatic compound-hydrogenated conjugated diene compound block copolymer exhibiting more preferable performance is, for example, Japanese Patent Publication No. 42-
The methods described in Japanese Patent Publication No. 8704 and Japanese Patent Publication No. 43-6636 may be used, but particularly in applications requiring high weather resistance and heat aging resistance, use of a titanium-based hydrogenation catalyst is recommended. , JP-A-60-220147, JP-A-61-33132 or JP-A-62-20.
The method described in Japanese Patent No. 7303 is cited. The aliphatic double bond derived from the conjugated diene compound at that time is at least 8
It is selected such that 0%, preferably 90% or more, is hydrogenated, while less than 20%, preferably less than 10%, of the vinyl aromatic compound is hydrogenated. The hydrogenation rate of the hydrogenated block copolymer can be easily known by infrared spectroscopic analysis or nuclear magnetic resonance analysis.

The component (b) of the present invention is a polyolefin resin, and specific examples thereof include polyethylene resin and polypropylene resin. Examples of the polyethylene resin include low density polyethylene, linear low density polyethylene, high density polyethylene, and a copolymer of ethylene and an α-olefin having 3 to 8 carbon atoms. Ethylene and carbon number 3 ~
In the case of the copolymer of 8 with the α-olefin, the α-olefin in the copolymer includes propylene, butene-1, isobutene, pentene-1, hexene-1, 4-methylpentene-1, octene-1 and the like. Can be given. Further, the proportion of α-olefin used is 30% by weight or less.

The polypropylene resin is a propylene homopolymer or a copolymer of propylene and an α-olefin having 2 to 8 carbon atoms (hereinafter abbreviated as propylene resin). In the case of a copolymer of propylene and an α-olefin having 2 to 8 carbon atoms, the α-olefin in the copolymer is ethylene, butene-1, isobutene, pentene-1,
Hexene-1,4-methylpentene-1, octene-1
Etc. Further, the proportion of α-olefin used is 30% by weight or less. These propylene-based resins can be synthesized by a conventionally known method. For example, a propylene homopolymer synthesized using a Ziegler-Natta type catalyst, or a random or block copolymer of propylene and α-olefin is used. can give.

The melt flow rate of these polyolefin resins (ASTM D1238, 230 ° C., 2.1
Value measured according to a 6 kg load. Hereinafter, abbreviated as MFR) is 0.1 to 4.5 g / 10 minutes. MFR is 0.
If it is less than 1 g / 10 minutes, the melt viscosity of the elastomer composition is high and extrusion at the time of blow molding cannot be performed, which is not preferable. Further, if the MFR exceeds 4.5 g / 10 minutes, the melt elongation of the elastomer composition is lowered and the blow moldability is lowered, which is not preferable.

The blending amount of the polyolefin resin as the component (b) in the present invention is such that the hydrogenated block copolymer 100
10 to 80 parts by weight, preferably 15 to 5 parts by weight
0 parts by weight. The blending amount of polyolefin resin is 10
If it is less than 1 part by weight, the melt elongation of the elastomer composition is lowered and the blow moldability is lowered, which is not preferable. When the blending amount of the polyolefin-based resin exceeds 80 parts by weight, the flexibility of the elastomer composition decreases, which is not preferable.

The hydrocarbon oil used as the component (c) in the present invention has the effect of improving the flexibility and processability of the composition obtained, and is a non-aromatic mineral oil or a liquid or low molecular weight oil. The synthetic softeners of are suitable. As the non-aromatic mineral oil, generally known paraffinic oils and naphthenic oils can be used, but paraffinic oils having an aromatic ring component of 10% by weight or less are preferred.

The blending amount of the component (c) hydrocarbon oil is 20 to 100 relative to 100 parts by weight of the hydrogenated block copolymer.
Parts by weight, preferably 30 to 70 parts by weight. When the blending amount of the hydrocarbon oil is less than 20 parts by weight, the flexibility of the elastomer composition decreases, and the extrudability of the elastomer composition,
It is not preferable because the melt elongation is lowered and the blow moldability is lowered. When the blending amount of the hydrocarbon oil exceeds 100 parts by weight, the strength and heat resistance of the elastomer composition are lowered, the melt viscosity of the elastomer composition is lowered, and drawdown occurs during blow molding, which is not preferable.

In general, any method known in the art for blending polymer components may be used to prepare the elastomeric compositions of the present invention.
In order to obtain the most homogeneous blend, a method of melt kneading using various kneaders such as a mixing roll, a kneader, a Banbury mixer and an extruder which are commonly used is preferable.

Prior to melt-kneading, these blends are previously dry-blended using a mixer such as a Henschel mixer, tumbler or ribbon blender, and the mixture is melt-kneaded to obtain a homogeneous elastomer composition. . The composition of the present invention contains, in addition to the above-mentioned components, an anti-blocking agent, a lubricant, a silicone oil, a pigment, carbon black, an inorganic filler, a heat stabilizer, an antioxidant, a light stabilizer, a flame retardant, if necessary. It is also possible to contain etc.

[0028]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In addition, in these Examples and Comparative Examples, the test methods used for various evaluation methods are as follows.

(1) Hardness [−] JIS K6301, A type (2) Tensile strength [kgf / cm ² ] JIS K6301, No. 3 dumbbell, 2 mm thick press sheet was used as a sample. (3) Elongation [%] JIS K6301, No. 3 dumbbell, 2 mm thick press sheet was used as a sample.

(4) Heat distortion temperature [° C.] A sample was cut out from a 2 mm thick press sheet and set in a thermomechanical analyzer (TMA). A load of 20 g / cm ² was applied to a 1 mmφ needle-inserted probe, and the probe was placed on the sample. 4 ° C /
The temperature was raised in minutes, and the temperature at which the needle-inserted probe was inserted by 200 μm was defined as the heat distortion temperature.

(5) Melt tension [g], maximum winding speed [m / min] Using a melt tension tester manufactured by Toyo Seiki Seisakusho,
It was measured under the following conditions. Cylinder diameter: 9.55 mm Orifice diameter: 2.09 mm Cylinder temperature: 210 ° C. Cylinder extrusion speed: 10 mm / min

(6) Blow Moldability Molded under the following conditions using a 50 mmφ blow molding machine manufactured by IHI. Cylinder temperature C1 180 ℃ C2 190 ℃ C3 190 ℃ Die temperature 200 ℃ Screw rotation speed 30 rpm Mold: Bottle of 500 ml capacity Blow ratio: 4 times

The components used in the examples and comparative examples are as follows. Component (a-1) -1 has a structure of B-A-B-A and has a number average molecular weight of 7,200.
Styrene / butadiene block copolymer having a molecular weight distribution of 0, a bound styrene content of 20% by weight, a 1,2-vinyl bond content of the polybutadiene portion before hydrogenation of 37% by weight, and a hydrogenation rate of the polybutadiene portion of 99%. The hydrogenated block copolymer (1) was synthesized by the method described in JP-A-60-220147.

Component (a-1) -2 has a structure of ABA, and has a number average molecular weight of 71,000, a molecular weight distribution of 1.2, a bound styrene content of 21% by weight, and 1,2 of the polybutadiene portion before hydrogenation. A styrene / butadiene block copolymer hydrogenated block copolymer having a vinyl bond content of 39% by weight and a polybutadiene portion hydrogenation rate of 99% was synthesized by the method described in JP-A-60-220147.

Component (a-1) -3 having a structure of ABA, having a number average molecular weight of 63,000, a molecular weight distribution of 1.1, a bound styrene content of 21% by weight, and 1 of the polyisoprene portion before hydrogenation. 4-bond amount is 94% by weight,
A hydrogenated block copolymer of a styrene / isoprene block copolymer having a 3,4-bond content of 6% by weight and a hydrogenation rate of 99% in a polyisoprene part is disclosed in JP-A-60-220147.
It was synthesized by the method described in the publication.

Component (a-1) -4 having a structure of ABA, having a number average molecular weight of 35,000, a molecular weight distribution of 1.1, a bound styrene content of 22% by weight, and 1,2 of the polybutadiene portion before hydrogenation. A hydrogenated block copolymer of a styrene / butadiene block copolymer having a vinyl bond content of 36% by weight and a polybutadiene portion hydrogenation rate of 99% was synthesized by the method described in JP-A-60-220147.

Component (a-2) -1 has the structure of BABA, and has a number average molecular weight of 12,000.
0, molecular weight distribution 1.25, bound styrene amount 35% by weight,
A hydrogenated block copolymer of styrene / butadiene block copolymer having a 1,2-vinyl bond content of 38% by weight in the polybutadiene portion before hydrogenation and a hydrogenation rate of 99% in the polybutadiene portion is disclosed in JP-A-60-220147. It was synthesized by the method described in the publication.

Component (a-2) -2 having the structure of ABA, number average molecular weight of 140,000,
The molecular weight distribution is 1.2, the bound styrene content is 31% by weight, and the 1,2-vinyl bond content of the polybutadiene portion before hydrogenation is 36.
A styrene / butadiene block copolymer hydrogenated block copolymer having a weight percentage of 99% and a polybutadiene portion hydrogenation rate of 99% was synthesized by the method described in JP-A-60-220147.

Component (a-2) -3 having a structure of ABA, number average molecular weight 141,000,
Molecular weight distribution 1.2, bound styrene content 34% by weight, polyisoprene part before hydrogenation 94% by weight 1,4-bonding amount, 3,4-bonding amount 6% by weight, hydrogenation rate of polyisoprene part A hydrogenated block copolymer of 99% styrene / isoprene block copolymer is disclosed in JP-A-60-2201.
It was synthesized by the method described in Japanese Patent Publication No. 47.

Component (b) -1 Asahi Kasei Kogyo, Asahi Polypro E1100, MFR 0.5 g
/ 10 minutes. Component (b) -2 Asahi Kasei Kogyo, Asahi Polypro E7100, MFR 0.5g
/ 10 minutes. Component (b) -3 Asahi Kasei Corp., Suntech-LD, M2206, MFR
1.7 g / 10 minutes. Component (b) -4 Asahi Kasei Kogyo, Asahi Polypro M1500, MFR8g / 1
0 minutes. Ingredient (c) Paraffin oil manufactured by Idemitsu Kosan. Diana Process Oil PW-380. (Kinematic viscosity: 381.6 cSt).

Examples 1 to 5 Hydrogenated block copolymers (a-1) -1, (a-
2) -1 is used as a polyolefin resin (b)-
1 was blended in a Henschel mixer at the ratios shown in Tables 1 and 2 and then melt-kneaded under the conditions of 220 ° C. in a 45 mm diameter same-direction twin-screw extruder to obtain pellets of an elastomer composition. . This was evaluated by the above test method, and the results are shown in Tables 1 and 2. From these results, it is clear that the elastomer of the present invention has excellent strength and heat resistance, good melting characteristics, and excellent blow moldability.

Comparative Examples 1-5 As hydrogenated block copolymers (a-1) -1, (a-
2) -1 is used as a polyolefin resin (b)-
1 and at each ratio shown in Table 3 and Table 4, Examples 1 to 1
Kneading and evaluation were carried out in the same manner as in Method 5. The results are shown in Tables 3 and 4. From this result, it is clear that the composition outside the scope of the present invention has poor blow moldability.

Examples 6 to 10 Hydrogenated block copolymers (a-1) -1, (a-
1) -2, (a-1) -3, (a-2) -1, (a-
2) -2, (a-2) -3, and (b) -1, (b) -2, (b) -3 as the polyolefin resin,
The respective proportions shown in Table 5 and Table 6 were kneaded and evaluated in the same manner as in the methods of Examples 1 to 5. The results are shown in Tables 5 and 6. From these results, it is clear that the elastomer of the present invention has excellent strength and heat resistance, good melting characteristics, and excellent blow moldability.

Comparative Examples 6 and 7 Hydrogenated block copolymers (a-1) -1, (a-
1) -3 and (a-2) -1, and (b) -1 and (b) -4 as the polyolefin-based resin at the respective ratios shown in Table 7 of Examples 1 to 5. Kneading and evaluation were performed in the same manner as in the method. The results are shown in Table 7. From these results, it has been clarified that good melt characteristics and blow moldability cannot be obtained even if hydrogenated block copolymers and polyolefin resins other than those described in the present invention are used.

[0045]

[Table 1]

[0046]

[Table 2]

[0047]

[Table 3]

[0048]

[Table 4]

[0049]

[Table 5]

[0050]

[Table 6]

[0051]

[Table 7]

[0052]

The elastomer composition of the present invention can be blow-molded by a method similar to that of a usual thermoplastic resin for blow molding, and it is possible to provide a molded article which is flexible, has high strength and is rich in heat resistance. Therefore, molded articles produced by blow molding from this composition can be used in fields of application such as general industrial materials and household products, but are particularly suitable for automobile parts due to their high flexibility, strength and heat resistance. Can be used for Further, since the elastomer composition is excellent in hygiene, it can be suitably used for various food containers, various medical instruments, and various medical containers.

Claims (3)

[Claims] 1. A hydrogenated block copolymer comprising at least two vinyl aromatic compound-based polymer blocks A and at least one conjugated diene compound-based polymer block B. A block copolymer mixture having the following composition: (a) 100 parts by weight of a block copolymer mixture having the following composition, (a-1) having a number average molecular weight of 45,000 to 95,000, and the polymer block A being a copolymer. Hydrogenated block copolymer constituting 12 to 24% by weight of: 50 to 90 parts by weight (a-2) having a number average molecular weight of 100,000 to 200,000
And the polymer block A constitutes 28 to 38% by weight of the copolymer, the hydrogenated block copolymer: 10 to 5
0 parts by weight (b) Polyolefin resin having a melt flow rate of 0.1 to 4.5 g / 10 min: 10 to 80 parts by weight, and (C) 20 to 100 parts by weight of hydrocarbon oil, which are excellent in blow moldability. Elastomer composition. 2. The vinyl aromatic compound is styrene,
The elastomer composition according to claim 1, wherein the conjugated diene compound is butadiene, isoprene, or a combination thereof. 3. The polyolefin resin is a propylene homopolymer and / or propylene and an α-containing 2 to 8 carbon atoms.
The elastomer composition according to claim 1, which is a copolymer with an olefin.