JPH06170914A - Manufacture of thermoplastic elastomer composition - Google Patents

Abstract

PURPOSE:To constitute a method so that manufacturing can be performed economically, stably and safely by a continuous process, by a method wherein ethylene-alpha-olefin copolymer rubber and polypropylene resin are supplied directly to a two-shaft extruding machine having two kneading belts at a specific weight ratio. CONSTITUTION:(a) 50-90wt.% ethylene-alpha-olefin copolymer rubber and (b) 50-10wt.% polypropylene resin are supplied directly to a two-shaft extruding machine having at least two kneading belts. (In this case, (a) and (b) are supplied before the first kneading belt.) A master batch comprised of (c) an organic peroxide which is to such an extent that the (a) is crosslinked partly and the (b) polypropylene resin is supplied through a supply part provided between the first kneading belt and the last kneading belt, heat-treated kin-ematically within the two-shaft extruding machine and a thermoplastic elastomer is manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a thermoplastic elastomer in which a rubber component obtained by dynamically heat-treating a polypropylene resin and an ethylene-α-olefin copolymer rubber is partially crosslinked.

[0002]

2. Description of the Related Art Polyolefin resin, ethylene-α-
A method for producing a thermoplastic elastomer by kneading an olefin copolymer rubber and a cross-linking agent in a kneader is disclosed in JP-A-48 / 48
No. 26838. Further, a method for producing a thermoplastic elastomer by kneading a polyolefin resin and a partially cross-linked ethylene-α-olefin copolymer rubber in advance in a kneader is known from JP-A-47-18943. A method for producing a thermoplastic elastomer by previously kneading a polypropylene resin and an ethylene-α-olefin copolymer rubber in a kneader, then adding a cross-linking agent and continuing the kneading (JP-A-52-112729), polypropylene. The resin and ethylene-α-olefin copolymer rubber are kneaded in a kneader in advance, and then a masterbatch consisting of a crosslinking agent / crosslinking reaction retarder / ethylene-α-olefin copolymer rubber is added to continue kneading. A method for producing a thermoplastic elastomer (JP-A-54-1386) is disclosed. These methods are not economical because they substantially use a batch-type kneader such as a Banbury mixer.

As a method for producing a continuously partially crosslinked thermoplastic elastomer, a method of directly feeding a particulate rubber to an extruder has been disclosed. (JP-A-58-2534
However, in these production methods, it is difficult to control the crosslinking reaction because the crosslinking agent (organic peroxide) is supplied together with the polyolefin resin and the ethylene-α-olefin copolymer rubber. Yes, again
The discharge amount must be reduced in order to increase the specific energy, and these were remarkable especially for a softer thermoplastic elastomer composition in which a large amount of rubber is mixed with the resin component.

[0004]

DISCLOSURE OF THE INVENTION The present invention employs a continuous process in a method for producing a thermoplastic elastomer obtained by dynamically heat-treating a resin component and a rubber component, which is economical, stable and safe. It aims at providing a simple manufacturing method.

[0005]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have found that (a) ethylene-α-
Olefin copolymer rubber 50-90% by weight, (b)
50 to 10% by weight of polypropylene resin is directly fed to a twin-screw extruder having at least two kneading zones (in this case, (a) and (b) are fed before the first kneading zone),
A masterbatch composed of (c) an organic peroxide and (b) a polypropylene-based resin to such an extent that (a) is partially cross-linked is supplied from a supply portion provided between the first kneading zone and the last kneading zone. The present invention has been completed by finding out a method for producing a thermoplastic elastomer characterized by being obtained by dynamically heat-treating in the twin-screw extruder.

The present invention will be described in detail below. In the present invention, an ethylene-α-olefin copolymer rubber (hereinafter referred to as a rubber component), a polypropylene resin (hereinafter referred to as a resin component) and, if necessary, a softening agent and the like are used. The ethylene-α-olefin copolymer rubber used in the present invention is a copolymer of at least ethylene and α-olefin, and as the α-olefin, propylene, 1-butene,
1-pentene, 1-hexene, 4-methylpentene-
Known monomers such as 1,1-octene can be used. Of these α-olefins, propylene is preferred. The ratio of ethylene to α-olefin is 40/60 ~
It is preferred that they are copolymerized in a weight ratio of 92/8, preferably 45 / 55-80 / 20. Such ethylene-α-olefin copolymer rubber includes those which can be produced by a known method. In a preferred mode, the ethylene-α-olefin copolymer rubber has a high molecular weight and is partially crystalline. More preferably, the MFR under JIS K7210 at 230 ° C and a load of 2.16 kg is 0.01 g.
/ 10 minutes or less and the crystallinity by X-ray is 5% or more.

In the ethylene-α-olefin copolymer rubber used in the present invention, a non-conjugated diene can be copolymerized in addition to ethylene and α-olefin. As the diene monomer, a non-conjugated diene having 5 to 20 carbon atoms, for example, 1,4-pentadiene, 1,4- and 1,
5-hexadiene, 2,5-dimethyl-1,5-hexadiene and 1,4-octadiene, cyclic dienes such as cyclohexadiene, cyclooctadiene and dicyclopentadiene, alkenyl norbornenes such as 5
-Ethylidene- and 5-butylidene-2-norbornene, 2-methallyl- and 2-isopropenyl-5-norbornene are used. Among these, those using ethylidene norbornene or dicyclopentadiene are preferable. When the diene monomer is copolymerized, it is desirable that the iodine value is 40 or less, preferably 30 or less.

While the ethylene-α-olefin copolymer rubber component described above can be substantially amorphous,
It is also possible to partially include crystals. These crystal components have a melting point peak value of 100 determined by DSC measurement.
It is possible to use even if the temperature is higher than or equal to 0 ° C, and it is also possible to use one that is from 100 ° C or lower to around room temperature. The optimum value of the crystallinity of the crystal component contained in rubber cannot be generally discussed. This is because increasing the amount of the crystalline component makes it possible to improve the strength of the thermoplastic elastomer composition, but the softening agent to be blended may be bleeding because it is eliminated by the crystals in the rubber component. The degree of crystallinity and the morphology of crystals (peak temperature of melting in DSC, etc.) need to be determined in consideration of the blending amount of the softening agent described later.

The shape of the ethylene-α-olefin copolymer rubber needs to be pellets, powders, beads, or crumbs because it can be directly fed to a twin-screw extruder.
It is preferably used in the form of powder and / or crumb. In such a state, it is convenient because oil extension is promptly performed when the softening agent is supplied to the twin-screw extruder.
Preferred powder and / or crumb shapes are disclosed in JP-A-4-
258639 or JP-A-4-261434.

The polypropylene resin in the present invention means isotactic homopolypropylene, syndiotactic homopolypropylene or ethylene, butene-
It is a random or block copolymer of α-olefin such as 1, pentene-1, hexene-1, 4-methylpentene-1 and propylene, and the crystal component is polypropylene. A known monomer such as a diene compound may be copolymerized in addition to these α-olefins as long as the effects of the invention are not impaired.

The blending amount of the ethylene-α-olefin copolymer rubber is 50 to 9 in 100% by weight of the total of (a) and (b).
Although the amount is 0% by weight, the effect of the method of the present invention is remarkably different from the conventionally known method in a region where the component (a) is particularly large, for example, 65% by weight or more. The polypropylene resin component contributes to improvement of heat resistance, mechanical strength and fluidity of the thermoplastic elastomer. JIS K-721
0 MFR under 230 ℃, 2.16kg load is 0.0
1 to 200 g / 10 minutes, preferably 0.1 to 20 g /
It's 10 minutes.

The polypropylene resin in the present invention can be modified with a polar monomer by using an organic peroxide within the range not departing from the gist of the present invention. These modified products are used for improving the adhesiveness and coating property of the composition. Known polar monomers such as α, β unsaturated carboxylic acids and / or their derivatives are preferably used.

Further, as these resin components, it is also possible to use a polyolefin resin containing a rubber component which can be produced by two-step polymerization such as a solution, gas phase or slurry method.

Examples of the organic peroxide used as the crosslinking agent in the present invention include dicumyl peroxide and di-t.
ert-butyl peroxide, 2,5-dimethyl-2,
5-di- (tert-butylperoxy) hexane,
1,3-Bis- (tert-butylperoxy-isopropyl) -benzene, tert-butylcumyl peroxide, 2,5-dimethyl-2,5-di- (tert-butylperoxy) -hexyne, 3,1,1 -The-ter
t-butylperoxy-3,3,5-trimethylcyclohexane, tert-butylperoxybenzoate,
Examples thereof include tert-butylperoxyisopropyl carbonate.

Further, it is also possible to use a crosslinking aid together with these crosslinking agents, if necessary. Examples of the crosslinking aid used here include sulfur, p-quinonedioxime,
p, p'-dibenzoylquinone dioxime, ethylene glycol dimethacrylate, pentaerythritol triacrylate, 1,3-butylene glycol dimethacrylate, trimethylolpropane trimethacrylate,
Triallyl cyanurate, triallyl isocyanurate, diallyl phthalate, diallyl terephthalate, polyethylene glycol dimethacrylate, 1,2-polybutadiene, N, N'-m-phenylene bismaleimide, maleic anhydride, neopentyl glycol diacrylate, glycidyl methacrylate. And so on.

In the method for producing a thermoplastic elastomer of the present invention, a softening agent can be blended if necessary. The preferred blending amount of the softening agent is 200 parts by weight or less based on 100 parts by weight of the component (a). The softening agent is added to improve the fluidity and flexibility of the thermoplastic elastomer of the present invention, and there are paraffin-based, naphthene-based, aromatic-based, polybutene-based, etc., but the purpose of the present invention is to Paraffin type, naphthene type and polybutene type are preferable.

In addition, as a compoundable composition, for example, an inorganic filler such as talc, carbon black, silica, calcium carbonate, barium sulfate, mica, calcium silicate or aluminum silicate can be compounded.
Further, if necessary, antioxidants, ultraviolet absorbers, stabilizers such as metal deterioration inhibitors, lubricants, antistatic agents, electrical property improvers, flame retardants, processability improvers, pigments and other resins, rubbers. Ingredients that are commonly ordinarily added can be added.

In the present invention, these ethylene-α-olefin copolymer rubbers (hereinafter referred to as rubber components) and resin components are components of the composition excluding the cross-linking agent before they are directly supplied to the twin-screw extruder. According to the above, additives, fillers, etc. are mixed in a non-molten state using a mixer such as a Henschel mixer, or rubber components, resin components and other components are mixed using two or more feeding devices. It can be directly supplied to the supply port of a twin-screw extruder.

The masterbatch resin component (hereinafter abbreviated as "PO masterbatch") composed of an organic peroxide / polypropylene resin used in the present invention is a component other than the PO masterbatch (that is, mainly a resin component, a rubber component and, if necessary, a component). Softening agent) is side-fed after melting, mixing and dispersing, that is, at least in a region after the first kneading zone. By side-feeding the PO masterbatch in this way, a crosslinking reaction occurs in the state where the rubber component and the resin component are sufficiently dispersed, so that the finally obtained composition is finely dispersed with partially crosslinked rubber particles and is good. Give good results.

The amount of the organic peroxide used as the crosslinking agent is preferably such that it is partially crosslinked.
Total amount of (a), (b) (further a softening agent if necessary) 10
0.05 to 2 parts by weight, preferably 0.
5 to 1.0 parts by weight. If the blending amount is less than 0.05 parts by weight, the degree of crosslinking of the component (a) is too small, resulting in heat resistance, compression set, and compression set of the thermoplastic elastomer of the present invention.
Insufficient rubber-like properties such as impact resilience. On the other hand, if the amount is more than 2 parts by weight, excessive molecular cleavage of the component (b) causes a decrease in tensile rupture strength and elongation at break of the thermoplastic elastomer. A method for producing such a PO masterbatch is, for example, a method in which a porous polypropylene-based resin and / or a powdery polypropylene-based resin is attached and / or impregnated with an organic peroxide.

When a liquid material is used as the organic peroxide, the PO masterbatch has a high organic peroxide concentration in the PO masterbatch (for example, about 10 wt% or more) and the polypropylene resin is in a powder form. This may cause a decrease in fluidity and may cause a problem in feed quantitativeness. In such a case, it is preferable to add an inorganic filler to the PO masterbatch. The preferred addition amount depends on the concentration of organic peroxide, but polypropylene-based resin 1
It is 2 to 200 parts by weight with respect to 00 parts by weight. The liquid used here includes a solution obtained by diluting an organic peroxide that is solid at room temperature with a liquid that does not significantly impair the performance of the organic peroxide such as liquid paraffin. In addition, the PO masterbatch does not significantly impair its performance,
It may contain other components.

A method of directly side-feeding an organic peroxide without using a PO masterbatch is also conceivable. In such a method, a rich organic peroxide comes into contact with the metal surface in a high temperature extruder. Therefore, there is a risk of fire, which is not preferable.

Further, such side feed is preferably carried out when the L / D of the twin-screw extruder is 30 or more. In particular, in order to sufficiently mix the resin component, the rubber component and, if necessary, the softening agent in the twin-screw extruder, at least the L / D of the kneading zone before the PO masterbatch feed is 4 or more, preferably 6 or more. Therefore, it is preferable to provide a reverse feed disk at least at one place in the kneading zone. Further, the L / D of the kneading zone after the PO masterbatch is supplied is 2 or more, preferably 4 or more.

Although a part of the softening agent can be supplied from the same supply port as the resin component and the rubber component as described above,
If you want to add a large amount of softening agent (eg rubber component 100
If the softening agent is 20 parts by weight or more with respect to parts by weight), blocking and bridging easily occur in the hopper of the feeder, so that stable supply is difficult. In such a case, for example, JP-A-4-261434 and JP-A-4-25863.
It is preferred to supply the softener using the method described in 9.

In kneading using a twin-screw extruder, it is necessary that the crosslinking reaction of the rubber component is substantially completed within the residence time of the resin component and the rubber component. The temperature of the dynamic heat treatment is a temperature sufficient to soften the polypropylene resin and is generally in the range of 100 ° C to 300 ° C. In particular, in the reaction area of the organic peroxide, it is preferable to set the cylinder temperature to be equal to or lower than the one-minute half-life temperature of the organic peroxide. However, the temperature at which the PO masterbatch is supplied is preferably 100 ° C or lower, and more preferably 60 ° C or lower. If the temperature of this portion is high, the reaction may occur before the organic peroxide is sufficiently dispersed, and the appearance of the molded article of the composition may be poor. (A) in the first kneading zone,
In order to improve the dispersion of (b) and the softening agent as required, it is preferable to operate the screw at a high rotation speed. It is preferably 200 rpm or more, more preferably 300 rpm.
rpm or more. Running at low speed is not preferable because the rubber component (a) will be poorly dispersed.

The twin-screw extruder used in the present invention is a co-rotating or counter-rotating extruder composed of two screws. As a specific example of such an extruder, a commercially available Warner extruder (made by Warner Co., Ltd. in West Germany), TEX
90 extruder (manufactured by Japan Steel Works), BT80 extruder (manufactured by Hitachi, Ltd.), TEM70 extruder (manufactured by Toshiba Machine), KTX7
0 extruder (made by Kobe Steel), PTE90 extruder (made by Mitsubishi Heavy Industries), etc. can be mentioned.

[0027]

EXAMPLES The present invention will be described below with reference to examples. (Measurement method) (MFR) JIS K7210 (Load 2.16kg 230 ℃) (HLMFR) JIS K7210 (Load 21.6kg 230 ℃) (Tensile breaking strength, elongation) JIS K6301 (Shore A hardness) ASTM D-676-49 (Appearance ) A sheet was formed using a 30 mmφ sheet forming machine, and the appearance of the surface was visually determined. The T-die has a slit width of 60 mm and a lip gap of 1 mm, the discharge rate is 3.0 kg / hr, and the take-up speed is 1.0 m / m.
in-6.0 m / min. (Raw material) [Powdered EPM] ethylene-propylene copolymer rubber (38% by weight of propylene, MFR 0.03 g / 10 mi)
n) [Clam-like EPDM] ethylene-propylene-ethylidene norbornene terpolymer rubber (propylene 26.5)
Wt%, ethylidene norbornene 4.9 wt%, MFR
0.1 g / 10 min) [PP-1] isotactic polypropylene resin (M
FR 0.5g / 10min, powder form) [PP-2] isotactic polypropylene resin (M
FR20g / 10min, powder form) [PP-3] isotactic polypropylene resin (M
FR20g / 10min, porous beads) [Softener] PW380 (paraffin softener, Idemitsu Kosan Co., Ltd.) [Crosslinking agent] Kayahexa AD (Kayakakuzo, 2,5-)
Dimethyl-2,5-di (tert-butylperoxy)
Hexane) [Cross-linking aid] Percalink 301 (manufactured by Kayaku Nouri Co.,
Triallyl isocyanurate) [Filler] NS1000 (Nitto Kouka, calcium carbonate)

(Examples 1 and 2) Same-direction twin-screw extruder KTX-58 manufactured by Kobe Steel, L / D = 42, barrel diameter 58 mm
Was performed using. 14 parts by weight of the raw material PP-1 excluding the softening agent, 46 parts by weight of the powdered EPM, 0.5 parts by weight of the cross-linking agent, 0.5 parts by weight of the cross-linking aid, and additives such as an antioxidant are added with a Henschel mixer. After mixing, feeding was performed from a hopper. The softening agent is supplied to the die side of the hopper and the liquid addition plate (C1) provided on the hopper side of the first kneading zone.
(Between C and C2) and was supplied by a quantitative feed using a gear pump (36 parts by weight). Further, between the first kneading zone and the second kneading zone (C6) to (PP-2 / crosslinking agent / filler = 62/8/30), a PO masterbatch comprising 6.
5 parts by weight was side-fed. The operating conditions of the extruder at this time are shown in Table 1. At this time, the composition could be stably obtained. The results are shown in Table 2 together with the comparative examples.

Example 3 0.3 part by weight of a cross-linking agent was added,
The same procedure as in Example 1 was carried out except that the powder-like EPM was changed to the crumb-like EPDM.

Example 4 Example 4 except that the PO masterbatch used in Example 1 was replaced with a PO masterbatch in which PP-3 was impregnated with 10% by weight of a crosslinking agent to 4.5 parts by weight. The same procedure as 1 was performed.

(Comparative Example) In Example 1, 6.5 parts by weight of the PO masterbatch side-fed from between the first kneading zone and the second kneading zone were put together from the hopper together with other components except the softening agent. The same procedure as in Example 1 was performed except that the supply was performed.

[0032]

[Table 1]

[0033]

[Table 2]

[0034]

EFFECTS OF THE INVENTION According to the present invention, it is possible to economically and stably produce a rubber-crosslinked thermoplastic elastomer-like composition with a small number of production steps. The thermoplastic elastomer composition thus obtained is an automobile part, for example, a bumper, a corner bumper, a side molding, a spoiler, a weak electric component, for example, a hose,
It is suitable for various packing, insulation sheets, etc., electric cable fields, for example, flexible cords, booster cables, civil engineering / construction materials fields, such as waterproof sheets, waterproof materials, etc. It can be easily molded by an ordinary molding method such as molding.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an example of a twin-screw extruder.

[Explanation of symbols]

 C1 Main raw material feeding stage C2-C5 First kneading zone C6 Master batch feeding stage C7 Second kneading zone C8 Venting stage C9 Final extrusion stage

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] March 24, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction content]

The masterbatch resin component (hereinafter abbreviated as "PO masterbatch") composed of an organic peroxide / polypropylene resin used in the present invention is a component other than the PO masterbatch (that is, mainly a resin component, a rubber component and, if necessary, a component). Softening agent) is side-fed after melting, mixing and dispersing, that is, at least in the region after the first kneading zone. By side-feeding the PO masterbatch in this way, a crosslinking reaction occurs in the state where the rubber component and the resin component are sufficiently dispersed, so that the finally obtained composition is finely dispersed with partially crosslinked rubber particles and is good. Give good results.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0023

[Correction method] Change

[Correction content]

Further, such side feed is preferably carried out when the L / D of the twin-screw extruder is 30 or more. In particular, in order to sufficiently mix the resin component, the rubber component and, if necessary, the softening agent in the twin-screw extruder, at least the L / D of the kneading zone before the PO masterbatch feed is 4 or more, preferably 6 or more. Therefore, it is preferable to provide reverse feed disks at least at one or more locations in the kneading zone. Also,
The L / D of the kneading zone after the PO masterbatch is supplied is 2 or more, preferably 4 or more. The kneading zone in the present invention is one in which one or more elements of a normal / reverse / neutral feeding kneading disk and / or a forward / reverse / neutral feeding rotor are continuously arranged among the elements usually used in a twin-screw extruder. It was done. Elements other than these may be used as long as they have a kneading ability equivalent to these.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0025

[Correction method] Change

[Correction content]

In kneading using a twin-screw extruder, it is necessary that the crosslinking reaction of the rubber component is substantially completed within the residence time of the resin component and the rubber component. The term "dynamically heat-treating" in the present invention means that at least at a temperature sufficient to soften the component (b), the crosslinking reaction of the component (a) is substantially completed in a twin-screw extruder. Kneading. The temperature of the dynamic heat treatment is a temperature sufficient to soften the polypropylene resin and is generally in the range of 100 ° C to 300 ° C. In particular, in the reaction area of the organic peroxide, it is preferable to set the cylinder temperature to be equal to or lower than the one-minute half-life temperature of the organic peroxide. However, the temperature at which the PO masterbatch is supplied is preferably 100 ° C or lower, and more preferably 60 ° C or lower. If the temperature of this portion is high, the reaction may occur before the organic peroxide is sufficiently dispersed, and the appearance of the molded article of the composition may be poor. It is preferable to operate the screw at a high rotation speed in order to improve the dispersion of (a), (b) and optionally the softening agent in the first kneading zone. The speed is preferably 200 rpm or more, more preferably 300 rpm or more. Running at low speed is not preferable because the rubber component (a) will be poorly dispersed.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

The blending amount of the ethylene-α-olefin copolymer rubber is 50 to 9 in 100% by weight of the total of (a) and (b).
When it is 0% by weight, (a) exceeds 90% by weight, the heat resistance is insufficient, and when it is less than 50% by weight, it is too hard as an elastomer. In the method of the present invention, the difference in effect from the conventionally known method is remarkable in the region where the component (a) is particularly large, for example, 65% by weight or more. The polypropylene resin component contributes to improvement of heat resistance, mechanical strength and fluidity of the thermoplastic elastomer. JIS K-7210 2
MFR under load of 2.16 kg at 30 ° C is 0.01-2
The amount is 00 g / 10 minutes, preferably 0.1 to 20 g / 10 minutes.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0028

[Correction method] Change

[Correction content]

(Examples 1 and 2) Same-direction twin-screw extruder KTX-58 manufactured by Kobe Steel, L / D = 42, barrel diameter 58 mm
Was performed using. 14 parts by weight of the raw material PP-1 excluding the softening agent, 46 parts by weight of the powdered EPM, 0.5 parts by weight of the cross-linking agent, 0.5 parts by weight of the cross-linking aid, and additives such as an antioxidant are added with a Henschel mixer. After mixing, feeding was performed from a hopper. The softening agent is supplied to the dies side of the hopper and the liquid addition plates (C1 and C) provided on the hopper side of the first kneading zone.
(Between 2) and a metered feed using a gear pump (36 parts by weight). Further, between the first kneading zone and the second kneading zone (C6) to (PP-2 / crosslinking agent / filler = 6
2/8/30) was side-fed with 6.5 parts by weight of a PO masterbatch. The operating conditions of the extruder at this time are shown in Table 1. At this time, the composition could be stably obtained. The results are shown in Table 2 together with the comparative examples.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Akira City Yamamoto Oita City, Oita Prefecture 2 Nakanosu, Showa Denko KK Oita Research Institute

Claims (1)

[Claims] 1. An ethylene-α-olefin copolymer rubber (50 to 90% by weight) and a polypropylene resin (50 to 10% by weight) (a) are directly supplied to a twin-screw extruder having at least two kneading zones. (In this case (a),
(B) is supplied before the first kneading zone), and (c) organic peroxidation to such an extent that (a) is partially cross-linked from the feeding part provided between the first kneading zone and the last kneading zone. A method for producing a thermoplastic elastomer composition obtained by supplying a masterbatch composed of a compound and (b) a polypropylene-based resin and dynamically heat-treating it in the twin-screw extruder.