JPH1121543A - Thermoplastic elastomer composition and molded article using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoplastic elastomer composition obtainable without using a complicated method such as dynamic crosslinking, which is flexible, and also is excellent in strength, profile extrudability and fusibility, and further is free from the problem of stickiness, and a molded article using the same, especially a gasket manufactured via fusing end surfaces thereof. SOLUTION: This thermoplastic elastomer composition comprises (a) 100 pts.wt. of a propylene-α-olefin copolymer comprising a crystalline propylenic polymer segment and an amorphous propylene-α-olefin copolymer segment wherein the proportion of the amorphous propylene-α-olefin copolymer segment in the total copolymer is 30 to 75 wt.%, (b) 10 to 200 pts.wt. of a hydrogenated product of a block copolymer represented by A-(B-A)n -(A is a polymer block derived from a monovinyl-substituted aromatic hydrocarbon, B is an elastomeric polymer block from a conjugated diene and n is an integer of 1 to 5) and (c) 30 to 200 pts.wt., relative to 100 pts.wt. of component b, of a softener for a rubber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a thermoplastic elastomer composition which is excellent in strength, flexibility, extrusion processability and heat fusion property.
It is another object of the present invention to provide a molded article obtained by subjecting the thermoplastic elastomer composition to extrusion molding and a gasket obtained by heat-sealing the end faces of the molded article.

[0002]

2. Description of the Related Art In various parts such as gaskets for building materials, automobile parts and home electric parts, where there is a need for flexibility, conventionally,
Vulcanized rubber was mainly used. However, if it is a vulcanized rubber, it has been difficult to apply it to a component having a complicated shape due to insufficient molding processability. Therefore, as a thermoplastic resin having excellent moldability and flexibility, it is sometimes replaced with a so-called thermoplastic elastomer composition. Examples of such a thermoplastic elastomer composition include an olefin-based elastomer composed of an ethylene-propylene copolymer rubber and polypropylene, a polyurethane-based elastomer, and soft vinyl chloride.

[0003]

However, even with these materials, profile extrusion, flexibility, economy,
Each of them had drawbacks in terms of recyclability and the like, and was not always satisfactory. For example, an olefin-based elastomer obtained by simply blending an ethylene-propylene copolymer rubber and polypropylene is relatively inexpensive and excellent in heat resistance and weather resistance, but is inferior in flexibility, compression set characteristics, and deformability. Therefore, in order to solve such a problem, a polyolefin-based thermoplastic elastomer composition in which a rubber component is partially or completely dynamically crosslinked has been proposed. However, although the improved thermoplastic elastomer composition is excellent in flexibility, heat resistance and compression set, it includes a step of crosslinking a rubber component, so that the production method is restricted and complicated. . In addition, when the thermoplastic elastomer composition is extrusion-molded, a residue is formed on a die, so-called scumming, or when formed by extrusion molding, the surface of a molded article is rough, or a sharp portion such as a corner portion or an edge portion is formed. However, there is a problem that it is difficult to form the resin smoothly. Further, polyurethane-based elastomers have disadvantages in that they are inferior in flexibility, processability and expensive. In addition, soft polyvinyl chloride is relatively inexpensive and excellent in moldability, but has a large temperature change in hardness and has a problem in flexibility at low temperatures. Also,
Its use is limited because of its large compression set. In recent years, the use of polyvinyl chloride resin, which causes the generation of hydrogen chloride at the time of incineration due to the problem of treating waste plastic, has been restricted.

An elastomer using a hydrogenated derivative of a vinyl aromatic compound-conjugated diene compound block copolymer (hereinafter abbreviated as a hydrogenated block copolymer) has been proposed as having excellent flexibility and profile extrusion moldability. Composition proposals have been made. For example, Japanese Patent Application Laid-Open No. 50-14742,
JP-A-52-65551 discloses compositions in which a hydrogenated block copolymer is blended with a rubber softener and a polypropylene-based polymer. However, although these compositions have better deformability than olefin-based elastomers, they still have the problem of poor heat sealability.

The present invention has been made to solve the above-mentioned problems, and is flexible, excellent in strength, excellent in extrudability, heat-fusibility, and sticky, without using a complicated method such as dynamic crosslinking. An object of the present invention is to provide a thermoplastic elastomer composition free from the problems described above, and a molded article using the same, particularly a gasket having an end face thermally fused.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above problems, propylene having specific physical properties was obtained.
The present inventors have found that a composition comprising an α-olefin block copolymer, a specific hydrogenated block copolymer and a softener for mineral oil-based rubber satisfies the above-mentioned object, and reached the present invention.

That is, the thermoplastic elastomer composition of the present invention comprises (a) a crystalline propylene polymer part and a non-crystalline propylene-α-olefin copolymer part. (B) The following characteristics (a) and (b) are based on 100 parts by weight of the propylene-α-olefin block copolymer in which the proportion of the non-crystalline propylene-α-olefin copolymer part is 30 to 75% by weight. formula A- (B-a) _n has a - (wherein a is a polymer block of monovinyl-substituted aromatic hydrocarbon, B is an elastomeric polymer block of a conjugated diene, n represents 1-5 integer 10) to 200 parts by weight of a hydrogenated derivative of the block copolymer represented by the following formula: (a) MLMFR is 0.1 g / 10 min or less. (Ii) Polymer block B is 90% in the block copolymer. ~
40% by weight (c) The mineral oil-based rubber softener has a content of 30 to 200 parts by weight based on 100 parts by weight of the component (b).

At this time, the propylene content of the non-crystalline propylene-α-olefin copolymer part in the component (a) is 50%.
It is preferably about 80 mol%. The main endothermic peak temperature T of the melting temperature of the component (a) measured by a differential scanning calorimeter.
It is preferable that mp is 120 ° C to 150 ° C and the main exothermic peak temperature Tcp of crystallization temperature is 85 to 105 ° C. In the block copolymer represented by the general formula A- (BA) _n- , A is a styrene polymer block, and B is a isoprene polymer block or a copolymer block of isoprene and butadiene. Preferably, there is. Furthermore, as a softener for mineral oil rubber, a softener for paraffin rubber is preferable. Such a thermoplastic elastomer composition is suitable for profile extrusion molding, and is suitable, for example, for a gasket obtained by heat-sealing the end faces of the molded product.

[0009]

DETAILED DESCRIPTION OF THE INVENTION Component (a) used in the present invention
Is a propylene-α-olefin block copolymer (hereinafter referred to as “BPP”), which is composed of a crystalline propylene-based polymer part and an amorphous propylene-α-olefin copolymer part. Examples of the crystalline propylene-based polymer portion include homopolypropylene or a random copolymer of propylene and a small amount of other α-olefin. On the other hand, examples of the non-crystalline propylene-α-olefin copolymer portion include a non-crystalline random copolymer of propylene and another α-olefin (α-olefin copolymerization ratio is 10 mol% or more). Examples of the other α-olefin include those having 2 to 12 carbon atoms (excluding 3), and specific examples thereof include ethylene, 1-butene,
-Methyl-1-butene, 3-methyl-1-pentene, 4
-Methyl-1-pentene, 4,4-dimethyl-1-pentene, vinylcyclopentane, vinylcyclohexane and the like. These α-olefins may be used alone or in combination of two or more.

The proportion of the non-crystalline propylene-α-olefin copolymer in the BPP is preferably from 30 to 75% by weight, more preferably from 40 to 70% by weight.
In the present invention, the proportion of the non-crystalline propylene-α-olefin copolymer part is determined by dissolving about 1% by weight of BPP in paraxylene at a temperature of 130 ° C. and then cooling to 25 ° C. It was determined by measuring the amount. Further, as the BPP of the present invention, the propylene content of the amorphous propylene-α-olefin copolymer part (F
It is desirable that p) is 50 to 80 mol%. Further, the BPP used in the present invention includes a main endothermic peak temperature Tmp measured using a differential scanning calorimeter (DSC).
Is preferably 120 to 150 ° C., and the main exothermic peak temperature Tcp of the crystallization temperature is preferably 85 to 105 ° C. T
mp is more preferably from 125 to 148 ° C,
30-145 ° C is preferred. When Tmp is less than 120 ° C., the obtained thermoplastic elastomer tends to be sticky and is inferior in heat resistance. On the other hand, when Tmp exceeds 150 ° C., the heat-fusibility deteriorates depending on the composition. Tcp is more preferably from 87 to 100 ° C, especially from 88 to 98 ° C.
Is preferred. If Tcp is less than 85 ° C., the extrudability deteriorates. On the other hand, if the temperature exceeds 105 ° C., the heat-fusibility deteriorates depending on the composition. In addition, the measuring method of Tmp and Tcp using a differential scanning calorimeter (DSC) is as follows. A sample is heated to 250 ° C., melted, and then cooled at a rate of 20 ° C./min to −30 ° C. The main exothermic peak temperature Tcp is determined from the peak curve. Next, after holding at −30 ° C. for 5 minutes, the main endothermic peak temperature Tmp is determined from an endothermic peak curve obtained when the temperature is increased to 250 ° C. at a rate of 20 ° C./min.

The BPP of the present invention comprises propylene and other α
-The olefin can be produced by a method such as batch polymerization or multi-stage polymerization in the presence of a Ziegler catalyst or the like. For example, in multistage polymerization, first, a crystalline propylene-based polymer is produced by polymerizing propylene in the presence of a Ziegler catalyst or the like, and in the next step, a mixture of propylene and another α-olefin is polymerized to form a non-crystalline polymer. Propylene-α-
An olefin copolymer is formed.

The component (b) used in the present invention is a hydrogenated derivative obtained by subjecting a block copolymer represented by the general formula A- (BA) _n- to a hydrogenation treatment. In the formula, A is a polymer block of a monovinyl-substituted aromatic hydrocarbon, and B is an elastomeric polymer block of a conjugated diene. n is an integer of 1 to 5. Monovinyl-substituted aromatic hydrocarbons as monomers constituting the polymer block A include styrene, α-methylstyrene, o-, m-
And p-methylstyrene, 1,3-dimethylstyrene,
Vinyl naphthalene, vinyl anthracene, etc.,
Styrene and α-methylstyrene are desirably used.
The conjugated diene monomer in the polymer block B is preferably butadiene or isoprene, or may be a mixture of both.

The melt flow rate (referred to as MLMFR) of the block copolymer measured at a temperature of 200 ° C. and a load of 10 kg in accordance with Condition 10 of Table 1 of JIS K7210 is 0.1.
1 g / 10 min or less, preferably 0.01 g / 10 min or less is required. If the MLMFR exceeds 0.1 g / 10 minutes, the mechanical properties such as the breaking strength and the compression set of the composition are remarkably deteriorated, and the molded product becomes sticky, which is not preferable. The ratio of the polymer block B in the block copolymer to the entire block copolymer is 90 to 4%.
It is preferably 0% by weight. When the amount of the copolymer block B is less than 40% by weight, it becomes difficult to maintain the elastomeric property after hydrogenation of the block copolymer, and when the amount exceeds 90% by weight, the mechanical strength is inferior. . In these hydrogenated derivatives of blog copolymers, at least 5 of the conjugated double bonds in polymer block B
Those in which 0% or more, preferably 80% or more are hydrogenated are preferable. As such a hydrogenated derivative of the block copolymer, for example, commercially available Septon (trade name) manufactured by Kuraray Co., Ltd. can be used.

The mixing ratio of component (a) to component (b) is 100 to 100 parts by weight of component (a) and component (b) is 10 to 200 parts by weight.
When the amount of the component (b) is less than 10 parts by weight, the resulting thermoplastic elastomer composition has insufficient flexibility and deteriorates the profile extrusion moldability. If the amount of the component (b) exceeds 200 parts by weight, the fluidity is remarkably reduced, the profile extrusion moldability is deteriorated, and the heat sealability is deteriorated.

The mineral oil-based rubber softener used as the component (c) of the present invention is added for the purpose of improving the fluidity and flexibility of the thermoplastic elastomer composition of the present invention. The mineral oil-based rubber softener is a mixture of an aromatic ring, a naphthene ring, and a paraffin chain in which the number of carbon atoms in the paraffin chain accounts for 50% or more of the total number of carbon atoms. And those having 30 to 45% of naphthenic ring carbons are naphthenic and having 3 aromatic carbon atoms.
Those with 0% or more are called aromatics and are classified.
The mineral oil-based rubber softeners used as the component (c) of the present invention are paraffinic and naphthene-based softeners in the above category, and aromatic softeners are dispersible with the component (b). Not preferred. In particular, the component (c) of the present invention is preferably a paraffinic one, and among the paraffinic ones, those having 5% or less of the aromatic ring component are particularly suitable.

The amount of the mineral oil-based softener incorporated in the composition of the present invention is from 30 to 20 parts by weight per 100 parts by weight of the component (b).
0 parts by weight, preferably 50 to 180 parts by weight. 20
Less than 10 parts by weight of the composition is inferior in fluidity and flexibility of the composition, and more than 200 parts by weight is not preferred because stickiness occurs in the molded product.

In the thermoplastic elastomer composition of the present invention, talc, calcium carbonate, silica, mica, calcium silicate, barium sulfate,
An inorganic filler such as carbon black can be blended. The amounts of the components (a), (b),
Usually, 60 parts by weight or less is appropriate for a total of 100 parts by weight of (c). Furthermore, additives such as an antioxidant, a weather resistance stabilizer, an antistatic agent, a lubricant, an antiblocking agent, an antifogging agent, an antistatic agent, a flame retardant, a processability improver, and a pigment are added as necessary. can do.

As the melt-kneading apparatus, conventionally known apparatuses such as an open-type mixing roll, a non-open-type Banbury mixer, an extruder, a kneader, and a continuous mixer can be used. Of these, it is preferable to use a non-open type device, and it is preferable to knead the mixture in an atmosphere of an inert gas such as nitrogen.

The thermoplastic elastomer composition of the present invention comprises:
It is possible to mold with a commonly used thermoplastic resin molding machine, extrusion molding, calendar molding, vacuum molding,
Although a molding method such as injection molding can be applied, it is particularly excellent in molding workability and deformability extrudability of a complicated molded product such as a sharp portion such as a corner portion or an edge portion of a heteroformed product. Examples of the deformed extruded products of the present invention include (1) hollow deformed products (profile pipes, hollow profiles, chamber profiles, etc.), (2) open deformed products (open profiles, etc.), and (3) composite profiles (sectional profiles, inserts). Profile, etc.), (4) solid profile, (5) other (net, ribbed pipe, etc.). Use fields include home appliance parts (packing, hoses, OA equipment panels, edge materials, etc.),
Automotive interior / exterior parts (doors, instrument panels, etc.), building material parts (window frames, outer wall materials, shutters,
Rain gutters), civil engineering, agricultural materials (hollow plate materials, corrugated plate materials, honeycomb materials, joiners, nets, corrugated pipes, etc.). In addition, the composition of the present invention can improve the heat exchange strength between the end faces of the profile extruded product and the profile extruded product having an extremely small bonding area. It is particularly suitable for gaskets and the like for frames and doors of refrigerated (frozen) storages with a large temperature difference between cooling and heating, including packing.

[0020]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples. The method and apparatus for measuring various physical properties in the present invention are described below. [Ratio of amorphous propylene-α-olefin copolymer part in BPP] 1% by weight of BPP was dissolved in para-xylene at a temperature of 130 ° C, and the soluble matter (% by weight) when cooled to 25 ° C was calculated. This was determined as the ratio of the non-crystalline propylene-α-olefin copolymer part in BPP.

[Fp of Amorphous Propylene-α-Olefin Copolymer Part] The ^13C -NMR spectrum of the above-mentioned paraxylene-soluble component was measured by the following apparatus and measuring conditions to obtain Fp. Was. Measuring device: JNM-GSX400 manufactured by JEOL Ltd. ( ¹³ C nuclear resonance frequency: 100 MHz) Measurement mode: Proton decoupling method Pulse width: 8.0 μS Pulse repetition time: 5.0 s Integration frequency: 20,000 times Solvent: 1,2 Mixed solvent of 7,4-trichlorobenzene / deuterated benzene (75/25% by volume) Internal standard: hexamethyldisiloxane Sample concentration: 300 mg / 3.0 ml Solvent Measurement temperature: 120 ° C

[Tmp, Tcp] DSC measuring device (PERK
Sample (3-5 mg) using an IN-ELMER
℃ and melted, then -30 at a cooling rate of 20 ° C / min.
The main exothermic peak temperature Tcp was determined from the exothermic peak curve obtained when the sample was cooled to ° C. Next, after holding at -30 ° C for 5 minutes, the main endothermic peak temperature Tmp was determined from an endothermic peak curve obtained when the temperature was raised to 250 ° C at a rate of 20 ° C / min. [MFR] According to condition 14 of Table 1 of JIS K-7210, temperature 2
The measurement was performed at 30 ° C. and a load of 2.16 kg. [MLMFR] Measured at a temperature of 200 ° C. and a load of 10 kg in accordance with Condition 10 of Table 1 of JIS K-7210. [HLMFR] Measured under the conditions of a temperature of 230 ° C. and a load of 21.6 kg according to JIS K-7210. [Shore hardness] It was measured according to ASTM D-676-49.

[Tensile test] Breaking strength and breaking elongation were measured using a No. 3 dumbbell in accordance with JIS K6301 at a pulling speed of 200 mm / min. [Evaluation of heat sealability] A sheet having a thickness of 1 mm was press-formed at a temperature of 230 ° C, and a width of 15 m was used using a cutter knife.
m, cut to a length of 75 mm. Next, as shown in FIG.
The end faces 16, 16 of the two samples 10, 10 to be sandwiched and heat-fused while being taken out of the sections 2, 12 are brought into contact with a hot plate 14 at a temperature of 230 ° C. for 7 seconds, and immediately, as shown in FIG. Then, the end faces 16 are pressure-bonded to each other and are thermally fused. 24 at 23 ° C
After adjusting the hr state, as shown in FIG.
Dumbbell shape 20 so that 6 parts enter between marked lines 18
Into a sample for a tensile test. And JIS
According to K6301, pulling speed 200mm / min, between marked lines 1
A tensile test was performed under the conditions of 0 mm and a chuck-to-chuck distance of 30 mm, and the breaking strength and the breaking elongation were measured to evaluate the heat-fusibility. The breaking strength was a value obtained by dividing the load value at break (kgf) by 0.05 cm ² .

[Raw Materials] (a) Propylene-α-olefin block copolymer A block copolymer composed of a crystalline propylene polymer part and a non-crystalline ethylene-propylene copolymer part as a propylene-α-olefin block copolymer. Coalescing was used. Type (BPP-1 to BPP-3) and properties (ratio of non-crystalline propylene-α-olefin copolymer part, FP, Tm of non-crystalline propylene-α-olefin copolymer part)
p, Tcp) are shown in Table 1.

[Table 1]

(B) Hydrogenated derivative of block copolymer Table 2 shows the component (b) hydrogenated derivative of the block copolymer used.

[Table 2]

(C) Softener for mineral oil rubber PW-380 (paraffin oil, pour point: -15 ° C, kinematic viscosity: 98 ° C: 38.1 cst, flash point: 300 ° C) manufactured by Idemitsu Kosan Co., Ltd. ) Calcium carbonate (inorganic filler): NS1000 manufactured by Nitto Powder Chemical Co., Ltd. The following are raw materials used for comparison. (E) Polypropylene resin MD772H manufactured by Japan Polyolefin Co., Ltd. (propylene-ethylene random copolymer, ethylene content: 7
% By weight, MFR: 30 g / 10 min (f) Ethylene propylene copolymer rubber EP07P, manufactured by Japan Synthetic Rubber Co., Ltd. (propylene content: 27 wt%, MFR: 0.7 g / 10 min)

Examples 1 to 4 The same direction twin screw extruder KTX-3 as shown in Table 3 contains the above-mentioned polypropylene-α-olefin block copolymer, a hydrogenated derivative of the block copolymer and a mineral oil-based softener.
7 (manufactured by Kobe Steel Co., Ltd.) and melt-kneaded to obtain pellets. The obtained pellet was press-formed at 230 ° C. to obtain a sample for object evaluation. Table 3 shows the evaluation results.

Comparative Examples 1 to 4 Biaxial extrusion of the above ethylene-α-olefin copolymer rubber, a hydrogenated derivative of a block copolymer, a polypropylene resin and a mineral oil-based softener in the amounts shown in Table 4 in the same direction. Using a KTX-37 machine (manufactured by Kobe Steel Co., Ltd.), the mixture was melt-kneaded to obtain pellets. The obtained pellet was press-molded at 230 ° C. to obtain a sample for evaluating physical properties. Table 4 shows the evaluation results.

Comparative Example 5 Ethylene-propylene having a propylene content of 28 wt%, an iodine of 15, and a Mooney viscosity of ML _{1 + 4} (100 ° C.) 90
Ethylidene norbornene copolymer rubber 50% by weight, MF
R1 g / 10 min of homopolypropylene 20% by weight and mineral oil-based rubber softener (PW380) 30% by weight were kneaded with a Banbury mixer in a nitrogen atmosphere at 180 ° C. for 5 minutes, passed through a roll, and pelletized by a sheet cutter. Was manufactured. Next, 100 parts by weight of the pellets were mixed with Kayahexa AD (2,5-dimethyl-2,5-di-produced by Kayaku Akzo).
(T-butylperoxy) -hexane) 0.4 part by weight,
0.8 parts by weight of TAIC (triallyl isocyanurate) was mixed with a Henschel mixer, and the pellets were melt-kneaded using a co-axial twin screw extruder KTX-37 to obtain pellets of a partially crosslinked thermoplastic elastomer. . The obtained pellet was press-molded at 230 ° C. to obtain a sample for evaluating physical properties. Table 4 shows the evaluation results.

[0030]

[Table 3]

[0031]

[Table 4]

[0032]

According to the present invention, there can be obtained a thermoplastic elastomer composition having a good balance of mechanical strength, heat resistance, flexibility, heat fusibility and moldability. Moreover, there is no stickiness. In addition, since the thermoplastic elastomer composition is particularly excellent in profile extrusion property and heat fusion property, it is useful as various gaskets such as a refrigerator door gasket that requires heat fusion between end faces.

[Brief description of the drawings]

FIG. 1 is a side cross-sectional view showing a process for producing a sample for a tensile test for evaluation of heat sealability.

FIG. 2 is a plan view showing a manufacturing process of a sample for a tensile test for evaluation of heat fusion property.

Claims (7)

[Claims] (1) a crystalline propylene polymer part,
A propylene-α copolymer comprising an amorphous propylene-α-olefin copolymer part, wherein the proportion of the amorphous propylene-α-olefin copolymer part in all the copolymers is 30 to 75% by weight. -With respect to 100 parts by weight of the olefin block copolymer, (b) a general formula A- (B-
A) _n- (where A is a polymer block of a monovinyl-substituted aromatic hydrocarbon, B is an elastomeric polymer block of a conjugated diene, and n is an integer of 1 to 5) 10 to 200 parts by weight of a hydrogenated derivative of the polymer, (a) MLMFR is 0.1 g / 10 min or less (b) Polymer block B is 90 to 90 parts by weight in the block copolymer
40% by weight (c) The thermoplastic elastomer composition, wherein the mineral oil-based rubber softener has 30 to 200 parts by weight based on 100 parts by weight of the component (b). 2. The propylene content of the non-crystalline propylene-α-olefin copolymer part in the component (a) is 50 to 50.
The thermoplastic elastomer composition according to claim 1, wherein the amount is 80 mol%. 3. The main endothermic peak temperature Tmp of the melting temperature of the component (a) measured by a differential scanning calorimeter is 120 ° C. to 150 ° C.
° C, and the main exothermic peak temperature Tcp of the crystallization temperature is 85.
The thermoplastic elastomer composition according to claim 1 or 2, wherein the temperature is from 105 to 105 ° C. 4. In the block copolymer represented by the general formula A- (BA) _n- , A is a styrene polymer block, and B is a polyisomer block of isoprene or a copolymer of isoprene and butadiene. The thermoplastic elastomer composition according to any one of claims 1 to 3, wherein the composition is a polymer block. 5. The thermosetting elastomer composition according to claim 1, wherein the mineral oil-based rubber softener is a paraffin-based rubber softener. 6. A molded article obtained by subjecting the thermoplastic elastomer composition according to any one of claims 1 to 5 to profile extrusion molding. 7. A gasket, wherein end faces of the molded article according to claim 6 are heat-sealed.