JPH0768432B2 - Thermoplastic elastomer composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a molding processability, abrasion resistance, heat resistance, and oil resistance composed of a vinyl aromatic compound-conjugated diene block copolymer having a specific structure and polyurethane. , A thermoplastic elastomer composition having excellent tensile strength and tear strength.

(Prior Art) A vinyl aromatic compound-conjugated diene-based block copolymer has high rubber elasticity without being crosslinked, and in addition, it is easy to mold with a normal thermoplastic resin molding machine and can be recycled. It is widely used as a molding material for various industrial products or a modifier for thermoplastic resins because it has excellent properties such as

However, its wear resistance, oil resistance, heat resistance, tensile strength, and tear strength are not sufficient, which is a major obstacle to its use.

On the other hand, polyurethane, especially thermoplastic polyurethane, is used for shoe soles, hoses, tubes, machine parts, belts, etc. because it has excellent properties such as abrasion resistance, oil resistance, and heat resistance. Since it changes abruptly, the range of molding temperature is narrow and the molding process is not easy, and there is a problem that its use is limited while having excellent performance.

JP-A-56-115352 proposes a composition of a vinyl aromatic compound-conjugated diene block copolymer containing a dicarboxylic acid group and a polyurethane.

However, although the composition has excellent wear resistance, heat resistance and oil resistance, it is still insufficient in moldability, tensile strength and tear strength.

(Problems to be Solved by the Invention) As a result of intensive studies to solve the above-mentioned drawbacks, the inventors of the present invention identified a composition of a vinyl aromatic compound-conjugated diene block copolymer and polyurethane. The present inventors have found that the compounding of a vinyl aromatic compound-conjugated diene-based block copolymer having a structure and polyurethane can greatly improve molding processability, tensile strength, and tear strength, and arrived at the present invention.

(Means for Solving the Problem) The present invention provides the following (A) vinyl aromatic compound-conjugated diene-based block copolymer and / or (B) vinyl aromatic compound-conjugated diene-based block copolymer Component (a) consisting of 5 to 95% by weight and polyurethane component (b) 95 to 5
And a thermoplastic elastomer composition.

(A) Vinyl aromatic compound-conjugated diene block copolymer: containing 15 to 95% by weight of a vinyl aromatic compound and having the general formula AB
Is -A or (A-B _n X (wherein A a vinyl aromatic compound polymer block, the total amount of A contains 50 to 97 wt% of the total vinyl aromatic compound, B is a conjugated diene and a vinyl A copolymer with an aromatic compound, wherein the B portion has 2 to 8 tapered blocks in which the vinyl aromatic compound is gradually increased, n is an integer of 3 to 6, and X is a residue of a coupling agent.
And the content of the vinyl aromatic compound constituting a chain in which 1 or 4 or less monomer units among the vinyl aromatic compound are contained is 5
~ 25% by weight and a weight average molecular weight of 20,000-500,
A vinyl aromatic-conjugated diene-based block copolymer of 000.

(B) a vinyl aromatic compound - conjugated diene block copolymer (B): a vinyl aromatic compound comprises 20 to 80 wt%, the general formula (in A-B _n X (wherein, A: vinyl aromatics Polymer block, B: Random polymer block of 1 to 20% by weight of bonded vinyl aromatic compound and vinylene aromatic compound and conjugated diene, X: coupling agent residue, n: integer of 2 to 6). The present invention provides a vinyl aromatic-conjugated diene block copolymer having a weight average molecular weight of 20,000 to 500,000.

The present invention will be described in detail below.

The present invention uses the vinyl aromatic compound-conjugated diene block copolymer (A) and / or the vinyl aromatic compound-conjugated diene block copolymer (B) having the above-described specific structure to mold A composition excellent in workability, wear resistance, oil resistance, heat resistance, tensile strength and tear strength can be obtained.

The weight average molecular weight of the block copolymer (A) is 20,0.
Although it is from 00 to 500,000, it is preferably from 50,000 to 500,000, more preferably from 50,000 to 450,000 in view of the balance of moldability, tensile strength and tear strength.

As the vinyl aromatic compound, styrene, α-methylstyrene, p-methylstyrene, m-methylstyrene, o
-Methylstyrene, p-tert-butylstyrene, dimethylstyrene, vinylnaphthalene and the like can be used, and styrene is preferable among them. As the conjugated diene, butadiene, isoprene, piperylene and the like can be used, and of these, butadiene and isoprene are preferable.

The block copolymer (B) has a polymerization average molecular weight of 20,000.
However, it is preferably 100,000 to 500,000, and more preferably 100,000 to 450,000 in view of the balance of physical properties such as moldability, tensile strength and tear strength.

Within the range of the specific structures of the vinyl aromatic compound-conjugated diene compounds (A) and (B) shown above, a thermoplastic elastomer composition having the molding processability, tensile strength and tear strength, which is the object of the present invention, is obtained. Is obtained.

In the composition of the present invention, vinyl aromatic compound-conjugated diene block copolymer (A) and / vinyl aromatic compound-conjugated diene block copolymer in the total amount of components (a) and (b). The content (a) of (B) is 5 to 95% by weight, preferably 10 to 90% by weight, more preferably 10 to 80% by weight. If it is less than 5% by weight, moldability is poor, while if it exceeds 95% by weight, tensile strength, tear strength, wear resistance,
Heat resistance and oil resistance are inferior, which is not preferable.

The polyurethane of the present invention is a polymer having a repeating unit of urethane bond in its molecule, and is used for foams, adhesives, paints, synthetic leathers, elastomers, diisocyanates, polyols, polyamines, glycols, etc. It is produced as a raw material by a typical production method using these polyaddition reactions. The types of these polyurethane elastomers include various types such as pressure mold, kneading, and thermoplastic, each of which has its own unique characteristics. Any of these can be used in the present invention, and among them, thermoplastic polyurethane is most advantageous in terms of processability. Thermoplastic polyurethanes are classified into full thermoplastic type and incomplete thermoplastic type according to their synthesis conditions, and these are determined by the molar ratio of the bifunctional polyol as a raw material, the OH group of glycol and the NCO group of diisocyanate,
The one synthesized at about 0.95 <NEC / OH ≦ 1 is the completely thermoplastic type, and the one synthesized at about 1 <NCO / OH <1.1 is the incompletely plastic type. As the above-mentioned thermoplastic polyurethane, for example, a block of polyol (polyester or polyether) and diisocyanate is a soft segment, and a block of diisocyanate and a glycol is a hard segment.

Examples of the above-mentioned raw material polyester diol include poly (1,4-butylene adipate), poly (1,6-hexane adipate), polycaprolactone, and the like, and examples of the polyether diol include polyethylene glycol, polypropylene glycol, and poly (glycol). Oxytetramethyl glycol and the like. Further, examples of the glycol include ethylene glycol, 1,4-butanediol, 1,6-hexanediol and the like, and among these, polyether diol is preferable. The diisocyanate includes aromatic, alicyclic and aliphatic diisocyanates such as tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate.

In addition to the thermoplastic polyurethane elastomers shown above,
Even polyurethanes used for adhesives, foams, coatings, etc. have sufficient compatibility with the vinyl aromatic compound-conjugated diene block copolymer of the present invention and are used in the composition of the present invention. be able to.

As a thermoplastic polyurethane, the molecular weight is 5,000-50
Those of 0,000, preferably 10,000 to 300,000 can be favorably used in terms of mechanical properties.

For polyurethane, the softening point (JIS K7206) is
It is preferably 70 to 150 ° C, more preferably 80 to 130 ° C.
belongs to.

Also, the preferable impact resilience at 23 ℃ (JIS K6301) is
30% to 70%, more preferably 40 to 65% tensile strength at 23 ℃ (JIS K6301) is, 250~550kg / cm ^2, even more preferably those 300~550kg / cm ^2.

In the composition of the present invention, the amount of polyurethane (b) is 5 to 95% by weight, preferably 10 to 90% by weight, more preferably 20 to 90% by weight based on the total amount of components (a) and (b). % By weight.

If it is less than 5% by weight, tensile strength, tear strength, wear resistance,
Poor heat resistance and oil resistance. On the other hand, if it exceeds 95% by weight, the moldability becomes poor, which is not preferable.

Next, a method for producing the vinyl aromatic compound-conjugated diene-based block copolymers (A) and (B) will be described.

The vinyl aromatic compound-conjugated diene block copolymer (A) is prepared by adding an ether or a tertiary amine to a hydrocarbon solvent and using an organic lithium compound as an initiator to polymerize the vinyl aromatic compound. After the polymerization reaction is substantially completed, the mixture of the vinyl aromatic compound and the conjugated diene compound is divided into 2 to 8 times and polymerized in the same manner as above,
If necessary, the same amount of conjugated diene as that of one addition is then added and polymerization is carried out.

Further, the block copolymer represented by the general formula A-B-A is obtained by subsequently polymerizing a vinyl aromatic compound. In addition, the general formula (A
The block copolymer (B) of —B _n X is then obtained by performing a coupling reaction using a conventionally known coupling agent such as tetrachlorosilane.

In the step of polymerizing the mixture of the vinyl aromatic compound and the conjugated diene in 2 to 8 times, the amount of the monomer used each time is preferably the same, and the monomer is added as a method. The mixture may be added, or the conjugated diene and the vinyl aromatic compound may be added separately at the same time.

The preferred chain distribution amount of the vinyl aromatic compound in the block copolymer is determined by the amount of the ether, or the third group in the hydrocarbon solvent.
It is obtained by adding 0.005 to 5 parts by weight, preferably 0.005 to 0.5 parts by weight, of a primary amine per 100 parts by weight of the monomer.

The vinyl aromatic compound-conjugated diene-based block copolymer (B) used in the present invention is, for example, a vinyl aromatic compound in the presence of an ether or a tertiary amine with an organic lithium compound as an initiator in a hydrocarbon solvent. Is obtained by copolymerizing a vinyl aromatic compound and a conjugated diene, and then coupling with a silicon halide compound. The random copolymer of the vinyl aromatic compound and the conjugated diene in the B portion is a hydrocarbon. It is obtained by adding ether or a tertiary amine as a randomizer into a solvent and polymerizing. Therefore, in the polymerization method which does not use such a randomizer, the randomness of the vinyl aromatic compound of the B moiety and the conjugated diene, which is the object of the present invention, cannot be obtained.

The addition of ethers or tertiary amines increases the vinyl bond content of the polyconjugated diene moiety, but the vinyl bond content is preferably 5 to 50% by weight, more preferably 15 to 30% by weight. When the vinyl bond is 5% by weight or more, the vinyl aromatic compound in the B portion and the conjugated diene are substantially random copolymers. From this viewpoint, the amount of the ether or tertiary amine used is 0.5 to 100 parts per 100 parts of the monomer.
20 parts is preferred.

The coupling agent, divinyl aromatic compounds such as divinylbenzene, dipromomethane, dipromoethane, dipromopropane, methylene chloride, dichloroethane, dihalogenated hydrocarbons such as dichloropropane, dichlorobutane, dimethyldichlorosilane, diethyldichlorosilane, Dialkyldihalogenated silicon compounds such as dimethyldibromosilicon, diethyldichlorosilicon, diethyldibromosilicon, bromoform, chloroform, carbon tetrabromide, carbon tetrachloride, tribromoethane, trichloroethane, tribromopropane, trichloropropane, tetrabromoethane, tetra Trihalohydrocarbons such as bromopropane, tetrachloroethane, tetrachloropropane, etc., tetrahalohydrocarbons, ethyl benzoate, phenyl benzoate, methyl benzoate Carboxylic acid Enuteru such as ethyl acetate, tri-bromo silanes, Four chlorocinnamic arsenide, four Buromokei arsenide, monomethyl trichlorosilane silicon, silicon halides such monomethyl tribromo silicic arsenide, bistrichloromethyl stannyl ethane or the like is used.

Of these, silicon halides are preferred.

The amount of the coupling agent used is 1 equivalent of the lithium atom at the terminal of the block copolymer to the halogen atom of the coupling agent.
The amount is preferably 0.2 to 2 equivalents, more preferably 0.5 to 1.5 equivalents, particularly preferably 0.9 to 1.2 equivalents.

In addition, the coupling agent-carbon bond that forms a branch is preferably the coupling agent-conjugated diene bond rather than the coupling agent-vinyl aromatic compound bond in terms of mechanical strength.

Therefore, the branched block copolymer of the present invention is produced by forming a vinyl aromatic compound block using an organolithium initiator in the presence of an ether or a tertiary amine in a hydrocarbon solvent, and then conjugating it with a vinyl aromatic compound. Random copolymer block of diene is formed and then the organolithium initiator
Add 1 to 20 moles of conjugated diene per gram atom of Li,
The most preferred copolymer is obtained by carrying out the coupling reaction with a silicon halide compound.

The weight average molecular weight (MW) of the vinyl aromatic compound-conjugated diene block copolymers (A) and (B) was determined by gel permeation chromatography (GPC).
It can be measured under the conditions described in Japanese Patent Publication 5-7449.

In addition, the ratio of the vinyl aromatic compound chain divination was determined by a method developed by Professor Tanaka of the University of Agriculture and Technology.
29, No. 7, 2055).

In the composition of the present invention, a filler such as calcium carbonate, calcium silicate, clay, kaolin, talc, silica, diatomaceous earth, mica powder, asbestos, alumina, to the extent that the physical properties aimed at by the present invention are not impaired. , Barium sulphate, aluminum sulphate, calcium sulphate, basic magnesium carbonate, molybdenum disulfide, graphite, inorganic fillers such as carbon fiber, or colorants such as carbon black, ultramarine blue, titanium oxide, zinc white, red iron oxide, dark blue, azo Pigments, nitroso pigments, lake pigments, phthalocyanine pigments and the like can be added.

In particular, it is preferable to add an inorganic filler because the compatibility is further improved. A calcium salt is preferred as the filler. The preferable addition amount is preferably 2-200 parts by weight, more preferably 5-150 parts by weight, based on 100 parts by weight of the thermoplastic elastomer composition of the present invention.

Further, the composition of the present invention may further contain a thermoplastic resin, rubber, a thermoplastic elastomer plasticizer other than the present invention, a flame retardant, a crosslinking agent, an ultraviolet absorber, a softening agent and the like.

As the physical properties of the composition of the present invention, those having a Vicat softening point of 50 ° C. or higher are preferable, and the permanent elongation is preferably 20.
% Or less, more preferably 15% or less is particularly useful.

The thermoplastic elastomer composition of the present invention can be used for various moldings such as compression molding, injection molding, extrusion molding, and other ordinary molding methods for thermoplastic resins, such as footwear, toys, industrial parts, belts and hoses. It is used in various fields such as medical products, daily necessities, sheets, and films.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the examples as long as the gist of the present invention is not exceeded.

Examples (1) Vinyl aromatic compounds used in Examples and Comparative Examples
As the conjugated diene-based block copolymer (hereinafter, simply referred to as block copolymer), Table 1 shows the block copolymers used in Examples and Comparative Examples.

1) Block copolymers (a) to (d) (a) and (b) are the block copolymer (A) of the present invention, and (c) and (d) are the block copolymer (B) of the present invention. ) Is applicable.

(A)-(d) were manufactured by the method shown in the text.

2) Block copolymers (e) to (g) (outside the invention) In (e), the portion B is a tapered block, but the bonding mode of B and A is different from that of the block copolymer (A) of the present invention. It is a block copolymer outside the scope of the present invention.

(F) is a maleic anhydride-modified block copolymer obtained by adding 1.5 parts by weight of maleic anhydride to 100 parts by weight of (e) and graft reacting in an extruder.

(G) is a block copolymer having a number of tapered blocks in the B portion of 1 and a weight average molecular weight of 600,000, which is outside the range of the present invention.

(2) Evaluation method 1) Melt flow rate (MFR difference): Unit (g / 10 minutes) Under the condition of a load of 1.2 kg, two points of 200 ° C and 230 ° C were measured, and a MER value of 2 points doubled. The difference between

The difference in MER value is an index of moldability, and the smaller the difference between the two points, the wider the molding temperature range and the better the moldability.

2) Abrasion resistance: Unit (g / 1000 times) Measured according to ASTM D1044 using a Taber friction tester.

3) Vicat softening point: Unit (° C) Measured according to JIS K7260.

The larger the value that is an index of heat resistance, the better the heat resistance.

4) Oil resistance A 20 × 20 × 2 (mm) test piece was immersed in JIS No. 3 oil at 23 ° C. for 40 hours, and the volume change rate was shown in (%).

The smaller the value, the better the oil resistance.

5) Tensile strength (kg f / cm ² ), Elongation (%) Using a test piece obtained by punching out a JIS No. 1 dumbbell from a film having a thickness of 50 μm, it was measured at a tensile speed of 200 mm / min and at 25 ° C.

6) Tear strength (kg f / cm) Measured in accordance with JIS K6301 using a test piece having a thickness of 2 mm.

Examples 1 to 7 and Comparative Examples 1 to 5 Each component in the proportions shown in Table 2 and calcium carbonate in an amount of 10 parts with respect to 100 parts of the ingredients were added and mixed with a Henschel mixer, and a 50 mmφ single screw extruder was further added. Using, a pellet of the thermoplastic elastomer composition was obtained under the temperature condition of 200 ° C. The polyurethanes shown in Table 2 are thermoplastic polyurethanes Elastran E180PNAT and E195PANT manufactured by Nippon Elastran.

The evaluation results are shown in Table-2.

Examples 1 to 6 are thermoplastic elastomer compositions intended for the present invention.

Comparative Examples 1 to 3 are examples in which a block copolymer outside the scope of the present invention was used, and the moldability, tensile strength, and tear strength were poor.

Comparative Example 4 is an example in which the amount of the block copolymer is less than the range of the present invention, and the moldability is poor.

Comparative Example 5 is an example in which the amount of the block copolymer exceeds the range of the present invention, and the heat resistance, oil resistance, abrasion resistance, tensile strength and tear strength are poor.

(Effects of the Invention) A conventional thermoplastic elastomer composition of vinyl aromatic compound-conjugated diene block copolymer and polyurethane,
It has excellent oil resistance, heat resistance, and wear resistance, but it does not have sufficient moldability, tensile strength, and tear strength.

The thermoplastic elastomer composition of the present invention using the vinyl aromatic compound-conjugated diene-based block copolymer having a specific structure of the present invention has molding processability, tensile strength and tearing while maintaining the improvement effect of the conventional composition. Strength is improved. as a result,
It is a thermoplastic elastomer composition that gives higher quality products than before and can be applied to new applications, and that it has excellent molding processability, which improves productivity and has an extremely high industrial value. .

Claims (5)

[Claims] 1. A vinyl aromatic compound (A) shown below:
5 to 95% by weight of the component (a) comprising the conjugated diene block copolymer and / or (B) vinyl aromatic compound-conjugated diene block copolymer and the polyurethane component (b) 95 to
A thermoplastic elastomer composition comprising 5% by weight. (A) Vinyl aromatic compound-conjugated diene block copolymer: containing 15 to 95% by weight of a vinyl aromatic compound and having the general formula AB
Is -A or (A-B _n X (wherein A a vinyl aromatic compound polymer block, the total amount of A contains 50 to 97 wt% of the total vinyl aromatic compound, B is a conjugated diene and a vinyl A copolymer with an aromatic compound, wherein the B portion has 2 to 8 tapered blocks in which the vinyl aromatic compound is gradually increased, n is an integer of 3 to 6, and X is a residue of a coupling agent.
And the content of the vinyl aromatic compound constituting a chain in which 1 or 4 or less monomer units among the vinyl aromatic compound are contained is 5
~ 25% by weight and a weight average molecular weight of 20,000-500,
A vinyl aromatic-conjugated diene-based block copolymer of 000. (B) a vinyl aromatic compound - conjugated diene block copolymer: a vinyl aromatic compound comprises 20 to 80 wt%, in the general formula (A-B _n X (wherein, A: a vinyl aromatic compound polymer block , B: a random copolymer block of a vinyl aromatic compound and a conjugated diene in which the bound vinyl aromatic compound is 1 to 20% by weight, X: a coupling agent residue, and n: an integer of 2 to 6.). And a vinyl aromatic-conjugated diene block copolymer having a weight average molecular weight of 20,000 to 500,000. 2. A composition according to claim 1, wherein the polyurethane of component (b) is thermoplastic. 3. A composition according to claim 1, wherein the polyurethane of component (b) is a thermoplastic elastomer. 4. The component (b) polyurethane is a completely thermoplastic type synthesized by a ratio of the number of moles of the raw material diisocyanate compound to the number of moles of the raw material dihydroxy compound (NCO / OH) is 0.95 <NCO / OH ≦ 1. The composition according to claim 1. 5. The polyurethane of the component (b) is 1 <NCO / OH <.
The composition of claim 1 which is an incomplete thermoplastic type synthesized in 1.1.