Thermoplastic elastomer compositions and automotive weatherstrips

Abstract

To provide a thermoplastic elastomer composition that has excellent flowability in a wide temperature range and gives a molding having a good appearance.SOLUTION: Provided is a thermoplastic elastomer composition obtained by melt-kneading an ethylene / α-olefin / non-conjugated polyene copolymer rubber (A) that is a copolymer of ethylene, an α-olefin having 3 to 20 carbon atoms, and a non-conjugated polyene, a polyolefin resin (B), and a mineral oil-based softening agent (C) in the presence of an organic peroxide (D) and a crosslinking aid (E), the thermoplastic elastomer composition having a shear viscosity of from 5 Pa s to 20 Pa s at 140°C and 10,000 s-1.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to thermoplastic elastomer compositions and automotive weather strips. [Background technology]

[0002] Olefin-based thermoplastic elastomers are known to be obtained by dynamically heat-treating a composition consisting of an ethylene copolymer and a polyolefin resin in the presence of an organic peroxide (see, for example, Patent Document 1). Molding processes using such olefin-based thermoplastic elastomers have the advantage that a vulcanization process is not required in their manufacture, conventional thermoplastic resin molding methods such as injection molding, shape extrusion molding, calendering, and blow molding can be used, and that they can be applied to complex shapes.

[0003] On the other hand, because such olefin-based thermoplastic elastomers need to be heated to a molten state and molded by flowing them into a mold of a specific shape, if the set temperature or the flow characteristics of the thermoplastic elastomer material are insufficient, it may not be possible to mold them into a desirable shape, or quality or design defects such as flow marks or delamination may occur on the surface of the molded product.

[0004] To solve these problems, formulations that add plasticizers to thermoplastic elastomers have been considered, but there were concerns that the plasticizer components would bleed out of the molded product, leading to a decrease in resilience and material strength. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2014-193969 [Overview of the project] [Problems that the invention aims to solve]

[0006] Some aspects of the present invention provide thermoplastic elastomer compositions that exhibit excellent fluidity over a wide temperature range and result in a good appearance of molded articles. [Means for solving the problem]

[0007] The present invention has been made to solve at least some of the above-mentioned problems and can be realized in any of the following embodiments.

[0008] One aspect of the thermoplastic elastomer composition according to the present invention is: A composition obtained by melt-kneading an ethylene-α-olefin-non-conjugated polyene copolymer rubber (A), which is a copolymer of ethylene, an α-olefin having 3 to 20 carbon atoms, and a non-conjugated polyene, a polyolefin resin (B), and a mineral oil-based softener (C) in the presence of an organic peroxide (D) and a crosslinking aid (E), at 140°C and 10,000 s. -1 This is a thermoplastic elastomer composition having a shear viscosity of 5 to 20 Pa·s.

[0009] In one embodiment of the thermoplastic elastomer composition, In accordance with ISO 11357-3:2018, when differential scanning calorimetry is performed while the temperature is cooled from 200°C to -80°C at a rate of -10°C / min, the observed exothermic peak temperature can be between 70 and 85°C.

[0010] In one embodiment of the thermoplastic elastomer composition, When the polyolefin resin (B) is cooled from 200°C to -80°C at a rate of -10°C / min in accordance with ISO 11357-3:2018 and differential scanning calorimetry is performed, the sum of the observed peak heat generation is taken as 100%, and the temperature at which the accumulated peaks reach 95% when the sum of the observed peaks is calculated from the high-temperature side can be between 75 and 95°C.

[0011] In one embodiment of the thermoplastic elastomer composition, The mass ratio (C) / (A) of the mineral oil-based softener (C) to the ethylene·α-olefin·non-conjugated polyene copolymer rubber (A) can be in the range of 0.8 to 1.9.

[0012] In one aspect of the thermoplastic elastomer composition, When differential scanning calorimetry is performed by raising the temperature from -80°C to 200°C at a rate of 10°C / min in accordance with ISO 11357-3:2018, the heat absorption amount of the peak observed can be 1 to 25 J·g -1 -1.

[0013] In one aspect of the thermoplastic elastomer composition, When differential scanning calorimetry is performed by raising the temperature from -80°C to 200°C at a rate of 10°C / min in accordance with ISO 11357-3:2018, the heat absorption amount of the peak observed is 10.5 J·g -1 It can further contain an amorphous polyolefin resin (F) that is less than or equal to -1.

[0014] One aspect of the weatherstrip for automobiles according to the present invention uses the thermoplastic elastomer composition of any of the above aspects at least in part.

Advantages of the Invention

[0015] According to the thermoplastic elastomer composition of the present invention, since it has excellent fluidity in a wide temperature range, it is easy to mold into a preferred shape, and a molded product with a good appearance can be obtained.

Modes for Carrying Out the Invention

[0016] Hereinafter, preferred embodiments according to the present invention will be described in detail. It should be understood that the present invention is not limited only to the embodiments described below, and also includes various modifications implemented without changing the gist of the present invention.

[0017] In this specification, a numerical range described using "X to Y" is interpreted as including numerical value X as the lower limit value and including numerical value Y as the upper limit value.

[0018] In this specification, ethylene-α-olefin-non-conjugated polyene copolymer rubber (A) may be abbreviated as "component (A)", polyolefin resin (B) as "component (B)", mineral oil-based softener (C) as "component (C)", organic peroxide (D) as "component (D)", crosslinking aid (E) as "component (E)", amorphous polyolefin resin (F) as "component (F)", and differential scanning calorimetry as "DSC measurement".

[0019] 1. Thermoplastic elastomer composition A thermoplastic elastomer composition according to one embodiment of the present invention is a composition obtained by melt-kneading an ethylene-α-olefin-non-conjugated polyene copolymer rubber (A), which is a copolymer of ethylene, an α-olefin having 3 to 20 carbon atoms, and a non-conjugated polyene, a polyolefin resin (B), and a mineral oil-based softener (C) in the presence of an organic peroxide (D) and a crosslinking aid (E). In this embodiment, the thermoplastic elastomer composition forms a sea-island structure with component (A) as the dispersed phase and component (B) as the continuous phase.

[0020] In the thermoplastic elastomer composition according to this embodiment, the blending ratio of mineral oil-based softener (C) is such that the mineral oil-based softener (C) and ethylene-α-olefin-non-conjugated polyene copolymer The mass ratio (C) / (A) of (A) is preferably in the range of 0.8 to 1.9, more preferably in the range of 0.9 to 1.8, and particularly preferably in the range of 1.0 to 1.7. When the blending ratio of the mineral oil-based softener (C) is within the above range, the thermoplastic elastomer composition is given appropriate fluidity and the occurrence of oil bleeding can be suppressed.

[0021] The thermoplastic elastomer composition obtained in this way was subjected to 140°C and 10,000 s. -1The shear viscosity is 5 to 20 Pa·s, preferably 5.5 to 19.5 Pa·s, more preferably 6 to 19 Pa·s, even more preferably 6.5 to 18.5 Pa·s, and particularly preferably 7 to 18 Pa·s.

[0022] Furthermore, in DSC measurements taken in accordance with ISO 11357-3:2018, where the temperature was lowered from 200°C to -80°C at a rate of -10°C / min, the temperature at which the exothermic peak was observed was preferably 70-85°C, more preferably 70-84°C, and particularly preferably 70-83°C.

[0023] Furthermore, in accordance with ISO 11357-3:2018, the endothermic peak observed in DSC measurements, taken by raising the temperature from -80°C to 200°C at a rate of 10°C / min, is preferably 1 to 25 J·g. -1 And more preferably 2-24 J·g -1 And especially preferably 3-23J·g -1 That is the case.

[0024] Because the shear viscosity, exothermic peak temperature in DSC measurement, and endothermic amount of the thermoplastic elastomer composition according to this embodiment are within the aforementioned range, it exhibits fluidity even in a relatively low temperature range compared to typical molding temperatures, and can be molded without causing significant defects in the molded appearance.

[0025] The following describes each component included in the thermoplastic elastomer composition according to this embodiment.

[0026] 1.1. Ethylene-α-olefin-non-conjugated polyene copolymer rubber (A) Examples of the ethylene-α-olefin-non-conjugated polyene copolymer rubber (A) used in this embodiment include random copolymers mainly composed of ethylene and α-olefins having 3 to 10 carbon atoms, such as ethylene-propylene-non-conjugated diene terpolymer rubber and ethylene-1-butene-non-conjugated diene terpolymer rubber.

[0027] Examples of the above-mentioned α-olefins having 3 to 10 carbon atoms include propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 3-methyl-1-pentene, 4-methyl-1-pentene, 3-ethyl-1-pentene, 1-heptene, 1-octene, and 1-decene. These can be used individually or in combination of two or more. Of these, propylene and 1-butene are particularly preferred.

[0028] Examples of the non-conjugated dienes mentioned above include 1,4-pentadiene, 1,4-hexadiene, 1,5-hexadiene, 1,7-octadiene, 1,9-decadiene, 3,6-dimethyl-1,7-octadiene, 4,5-dimethyl-1,7-octadiene, 5-methyl-1,8-nonadienene, dicyclopentadiene, 5-ethylidene-2-norbornene, 5-vinyl-2-norbornene, and 2,5-norbornadiene, which can be used individually or in combination of two or more. Of these, 1,4-hexadiene, dicyclopentadiene, and 5-ethylidene-2-norbornene are particularly preferred.

[0029] A specific example of component (A) is ethylene-propylene-dicyclopentadiene ternary copolymer. Examples include ethylene-propylene-5-ethylidene-2-norbornene terpolymer and ethylene-1-butene-5-ethylidene-2-norbornene terpolymer.

[0030] The ethylene content in these ternary copolymers is preferably 50 to 90% by mass, and more preferably 55 to 85% by mass, when the total of ethylene units, α-olefin units, and non-conjugated polyene units is taken as 100% by mass. The α-olefin content is preferably 5 to 40% by mass, and more preferably 10 to 35% by mass, when the total of ethylene units, α-olefin units, and non-conjugated polyene units is taken as 100% by mass. When the ethylene content of the above ternary copolymer is within the above range, the crosslinking efficiency tends to improve, and in some cases, the compression set characteristics can be kept low.

[0031] Furthermore, the non-conjugated polyene content consists of ethylene units, α-olefin units, and non-conjugated polyenes. Poly When the total amount including the en units is taken as 100% by mass, it is preferably 3 to 10% by mass, and more preferably 3 to 8% by mass.

[0032] The intrinsic viscosity [η] of the ethylene-α-olefin-non-conjugated polyene copolymer rubber (A), measured in decalin solvent at 135°C, is preferably 1 to 10 dl / g, more preferably 2 to 10 dl / g, and particularly preferably 3 to 9 dl / g.

[0033] Furthermore, the dispersion ratio (Mw / Mn) of the ethylene-α-olefin-non-conjugated polyene copolymer rubber (A) is preferably 5.0 or less, more preferably 4.5 or less, and particularly preferably 4.0 or less. Here, Mw represents the weight-average molecular weight and Mn represents the number-average molecular weight, and Mw and Mn are polystyrene-converted values ​​measured by gel permeation chromatography (GPC).

[0034] Component (A) may be formulated as an oil-expandable rubber to which a mineral oil-based softener (C), described later, is added during the manufacturing process. Formulating component (A) as an oil-expandable rubber tends to improve moldability.

[0035] The content of component (A) in the thermoplastic elastomer composition according to this embodiment is preferably 17 to 50% by mass, more preferably 20 to 47% by mass, and particularly preferably 22 to 44% by mass, when the total amount of components (A), (B), and (C) is 100% by mass.

[0036] 1.2. Polyolefin resin (B) In this embodiment, the polyolefin resin (B) used is preferably such that, in accordance with ISO 11357-3:2018, when the total amount of heat generation observed when the temperature is lowered from 200°C to -80°C at a rate of -10°C / min and measured by DSC, the temperature at which the observed peaks accumulate from the high temperature side to 95% is 75 to 95°C. Observing heat generation peaks down to low temperatures makes it easier to obtain a thermoplastic elastomer composition that does not solidify and remains fluid even at low temperatures. Such a thermoplastic elastomer composition can have the following characteristics: (1) a wider process window for molding than conventional materials, (2) less prone to defects such as poor molded appearance, and (3) can be processed even at relatively low temperatures, thus improving productivity.

[0037] Examples of polyolefin resins (B) include polypropylene, propylene-ethylene copolymer, propylene-1-butene copolymer, propylene-1-pentene copolymer, propylene-3-methyl-1-butene copolymer, propylene-1-hexene copolymer, propylene-3-methyl-1-pentene copolymer, propylene-4-methyl-1-pentene copolymer, propylene-3-ethyl-1-pentene copolymer, and propylene-1-octene copolymer. Examples include composites, propylene-1-decene copolymers, and propylene-1-undecene copolymers. Of these, polypropylene and propylene-ethylene copolymers are preferably used. These can be used individually or in combination of two or more.

[0038] The content of polyolefin resin (B) in the thermoplastic elastomer composition according to this embodiment is preferably 8 to 50% by mass, more preferably 10 to 40% by mass, and particularly preferably 12 to 35% by mass, when the total amount of components (A), (B), and (C) is taken as 100% by mass.

[0039] 1.3. Mineral oil-based softeners (C) The mineral oil-based softener (C) used in this embodiment preferably has a weight average molecular weight of 300 to 2000, particularly 500 to 1500. Rubber softeners composed of mineral oil hydrocarbons are generally a mixture of an aromatic ring, a naphthene ring, and a paraffin chain. Those in which the carbon number of the paraffin chain accounts for 50% or more of the total carbon number are paraffin oils, those in which the carbon number of the naphthene ring is 30 to 45% of the total carbon number are naphthene oils, and those in which the carbon number of the aromatic ring is 30% or more of the total carbon number are aromatic oils, and they are classified as such. However, in the present invention, paraffin-based ones are preferred, and particularly hydrogenated paraffin-based ones are preferred. Further, the mineral oil hydrocarbon has a kinematic viscosity at 40°C of 2×10 -5 ~8×10 -4 m 2 / s (20~800 cSt), particularly preferably 5×10 -5 ~6×10 -4 m 2 / s (50~600 cSt), and a pour point of -40 to 0°C, particularly preferably -30 to 0°C.

[0040] When the component (A) used in this embodiment is an oil-extended rubber, the extending oil contained in the oil-extended rubber is preferably also a mineral oil-based softener.

[0041] 1.4. Organic peroxide (D) The organic peroxide (D) used in this embodiment includes 1,3-di(tert-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexine-3, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexene-3, 1,3-bis(tert-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 2,2-di(tert-butylperoxy)-p-isopropylbenzene, dicumyl peroxide, di-tert-butyl peroxide, and tert-butyl peroxide. Examples of organic peroxides include tert-butylcumyl peroxide, p-menthane peroxide, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, dilauroyl peroxide, diacetyl peroxide, tert-butylperoxybenzoate, 2,4-dichlorobenzoyl peroxide, p-chlorobenzoyl peroxide, benzoyl peroxide, di(tert-butylperoxy)perbenzoate, n-butyl-4,4-bis(tert-butylperoxy)valerate, and tert-butylperoxyisopropyl carbonate. Among these organic peroxides, dialkyl peroxides such as 1,3-bis(tert-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexine-3, and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane are preferred.

[0042] From the viewpoint of achieving uniform and gentle partial crosslinking, the blending ratio of organic peroxide (D) is preferably 0.01 to 2.0 parts by mass, and more preferably 0.02 to 1.5 parts by mass, per 100 parts by mass of the total of components (A), (B), and (C).

[0043] 1.5. Crosslinking agent (E) In this embodiment, the crosslinking aid (E) is preferably a polyfunctional compound. In the present invention, a "polyfunctional compound" refers to a low-molecular-weight compound having two or more non-conjugated carbon-carbon double bonds in one molecule, which, when used in combination with other crosslinking agents that do not have such double bonds, efficiently promotes the crosslinking reaction and can exhibit a uniform crosslinked structure and excellent rubber elasticity.

[0044] Examples of polyfunctional compounds include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, diallyl phthalate, diallyl terephthalate, tetraallyl oxyethane, triallyl cyanurate, N,N'-m-phenylene bismaleimide, N,N'-toluene bismaleimide, bis(3-ethyl-5-methyl-4-maleimidophenyl)methane, divinylbenzene, and zinc di(meth)acrylate. These polyfunctional compounds may be used individually or in combination of two or more.

[0045] By using a polyfunctional compound that is highly reactive with free radicals generated during melt mixing, the crosslinking reaction proceeds rapidly, forming rubber domains with high crosslink density, while simultaneously suppressing side reactions other than the crosslinking reaction of free radicals (for example, disproportionation reactions between free radical species, hydrogen abstraction reactions not involved in the crosslinking reaction, and β-elimination reactions involving main chain severance of copolymer rubber or polyolefin resin).

[0046] The proportion of the crosslinking aid (E) is preferably 3 parts by mass or less, more preferably 0.1 to 1.5 parts by mass, and particularly preferably 0.2 to 1.2 parts by mass, based on 100 parts by mass of the total of components (A), (B), and (C), from the viewpoint of maintaining the uniformity of the phase structure and moldability.

[0047] 1.6. Amorphous polyolefin resin (F) In this embodiment, the amorphous polyolefin resin (F), which is optionally used, has a peak endothermic value of 10.5 J·g observed when measured by DSC after raising the temperature from -80°C to 200°C at a rate of 10°C / min, in accordance with ISO 11357-3:2018. -1 The following is preferable: Including such an amorphous polyolefin resin results in a composition with low hardness and maintains fluidity at low temperatures, while also providing a molded product with a good appearance.

[0048] Examples of amorphous polyolefin resins include homopolymers such as atactic polypropylene and atactic poly-1-butene, copolymers of propylene (containing 50 mol% or more) and other α-olefins (ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, etc.), and copolymers of 1-butene (containing 50 mol% or more) and other α-olefins (ethylene, propylene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, etc.). Of these, atactic polypropylene (propylene content of 50 mol% or more), copolymers of propylene (containing 50 mol% or more) and ethylene, and copolymers of propylene and 1-butene are particularly preferred. These can be used individually or in combination of two or more.

[0049] 1.7. Other Additives The thermoplastic elastomer composition according to this embodiment may contain various additives as needed, such as mineral oil-based softeners, lubricants, antioxidants, heat stabilizers, weathering agents, metal deactivators, UV absorbers, light stabilizers, copper damage inhibitors and other stabilizers, antibacterial and antifungal agents, dispersants, plasticizers, nucleating agents, flame retardants, silicone oils, silicone polymers, tackifiers, foaming aids, and titanium dioxide. It can be used in combination with colorants such as carbon black, metal powders such as ferrite, inorganic fibers such as glass fibers and metal fibers, organic fibers such as carbon fibers and aramid fibers, composite fibers, inorganic whiskers such as potassium titanate whiskers, glass beads, glass balloons, glass flakes, asbestos, mica, calcium carbonate, talc, silica, calcium silicate, hydrotalcite, kaolin, diatomaceous earth, graphite, pumice, evo powder, cotton floc, cork powder, barium sulfate, fluororesin, polymer beads, or mixtures thereof, fillers such as polyolefin wax, cellulose powder, rubber powder, wood powder, and low molecular weight polymers.

[0050] <Softeners other than mineral oil-based ones> While there are no particular restrictions on commonly used rubber softeners, examples include vegetable oils (such as coconut oil), esters of fatty acids and higher alcohols (such as phthalate diesters), phosphate triesters, polybutenes, polybutadienes, and other low molecular weight hydrocarbons.

[0051] 1.8. Measurement of physical properties 1.8.1. Peak Exothermic Temperature The exothermic peak temperature of the thermoplastic elastomer composition according to this embodiment is preferably 70°C or higher, more preferably 72°C or higher, even more preferably 73°C or higher, even more preferably 74°C or higher, and particularly preferably 75°C or higher. The exothermic peak temperature of the thermoplastic elastomer composition according to this embodiment is preferably 85°C or lower, more preferably 84°C or lower, even more preferably 83°C or lower, even more preferably 82°C or lower, and particularly preferably 81°C or lower. Because the exothermic peak temperature of the thermoplastic elastomer composition according to this embodiment is within the above range, it exhibits fluidity even in a relatively low temperature range compared to general molding temperatures, and can be molded without causing significant defects in the molded appearance.

[0052] The exothermic peak temperature of the thermoplastic elastomer composition was determined in accordance with ISO 11357-3:2018. The peak temperature was defined as the temperature at which the exothermic output was maximum when differential scanning calorimetry was performed using a differential scanning calorimeter (NETZSCH DSC, product name "204F1Phoenix") while the temperature was lowered from 200°C to -80°C at a rate of -10°C / min.

[0053] 1.8.2. Shear viscosity The shear viscosity of the thermoplastic elastomer composition according to this embodiment is 5 Pa·s or more, preferably 6 Pa·s or more, and more preferably 7 Pa·s or more. The shear viscosity of the thermoplastic elastomer composition according to this embodiment is 20 Pa·s or less, preferably 18 Pa·s or less, and more preferably 17 Pa·s or less. Because the shear viscosity of the thermoplastic elastomer composition according to this embodiment is within the above range, it exhibits fluidity even in a relatively low temperature range compared to general molding temperatures, and can be molded without causing significant defects in the molded appearance.

[0054] The shear viscosity of the thermoplastic elastomer composition was determined using a capillary rheometer (Rosand, product name "RH10") at 140°C with a shear rate of 10s. -1 from 100,000s -1 From the plot of viscosity against shear rate obtained by continuously changing it up to 10,000 s -1 The viscosity was calculated.

[0055] 1.9. Molded articles and applications The thermoplastic elastomer composition according to this embodiment can be molded into a molded article using various molding methods such as injection molding (e.g., gas injection molding, injection compression molding, short shot foam molding), extrusion molding, hollow molding, and compression molding. Among these, injection molding is preferred. For example, when performing injection molding, the molding temperature is generally 130 to 280°C. The temperature is in °C, preferably 150 to 250 °C. The injection pressure is usually 5 to 100 MPa, preferably 10 to 80 MPa. On the other hand, the mold temperature is usually 0 to 80 °C, preferably 20 to 60 °C. After these molding processes, the resulting molded body can be subjected to further secondary processes such as lamination molding or thermoforming.

[0056] The thermoplastic elastomer composition according to this embodiment is suitable for automotive components and building material components, and in particular for automotive weatherstrip components. Furthermore, the thermoplastic elastomer composition according to this embodiment is suitable for automotive parts (airbag storage cover, center panel, center console box, door trim, pillar, assist grip, steering wheel, weatherstrip, ceiling material, interior seat, bumper molding, side molding, air spoiler, air duct hose, cup holder, handbrake grip, shift knob cover, flapper door seal, wire harness grommet, rack and pinion boot, suspension cover boot, glass guide, inner beltline seal, roof guide, trunk lid seal, molded quarter window gasket, corner molding, glass enclosure It can be used in a wide range of fields, including insulation, hood seals, glass run channels, secondary seals, body panels, side shields, door coverings, hoses, wire harness covers, seat adjuster covers, various gaskets, etc.), civil engineering and construction materials (ground improvement sheets, water intake plates, noise and vibration prevention walls, and other civil engineering and construction materials, various gaskets and sheets for civil engineering and construction, waterproofing materials, joint materials, window frames, window frame gaskets, etc.), sanitary products (sanitary napkins, disposable diapers, toothbrush grips, etc.), sporting goods (golf club and tennis racket grips, etc.), industrial parts (medical containers, gaskets, packings, etc.), food parts (containers, packings, etc.), medical equipment parts, electric wires, general merchandise, toys, and more.

[0057] 2. Method for producing thermoplastic elastomer compositions The thermoplastic elastomer composition according to this embodiment is obtained by melt-kneading an ethylene-α-olefin-non-conjugated polyene copolymer rubber (A), a polyolefin resin (B), and a mineral oil-based softener (C) in the presence of an organic peroxide (D) and a crosslinking aid (E). In this invention, "melt-kneading" refers to both applying shear force and heating. By melt-kneading component (A) and component (B) in the presence of an organic peroxide (D) and a crosslinking aid (E), a thermoplastic elastomer composition having a sea-island structure is obtained in which component (A) is dispersed as a dispersed phase (island phase) within a continuous phase (sea phase) of component (B).

[0058] Examples of equipment capable of melt-kneading include open-type mixing rolls, closed-type Banbury mixers, kneaders, single-screw extruders, co-rotating continuous twin-screw extruders, and opposite-rotating continuous twin-screw kneaders. Furthermore, the processing performed by this kneading equipment may be in a batch or continuous manner.

[0059] The temperature conditions for melt mixing are preferably in the range of 150 to 250°C, from the viewpoint of balancing the melting of components (A) and (B) with the crosslinking reaction. The processing time for melt mixing is not particularly limited, but considering productivity, it is usually 0.1 to 30 minutes.

[0060] 3. Examples The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way by these examples. In the examples and comparative examples, "%" or "parts" refers to mass unless otherwise specified.

[0061] 3.1. Materials Used (1) Ethylene-α-olefin-nonconjugated polyene copolymer rubber For the ethylene-α-olefin-non-conjugated polyene copolymer rubber shown in Table 1 below, a mineral oil-based softener (product name "Diana Process Oil PW380", manufactured by Idemitsu Kosan Co., Ltd.) is used as shown in Table 1 below. The study used OSR-1 and OSR-2, which are oil-expanded ethylene-α-olefin-non-conjugated polyene copolymer rubbers containing these materials in specific proportions.

[0062] [Table 1]

[0063] The intrinsic viscosity in Table 1 above is the value of the intrinsic viscosity of ethylene-α-olefin-non-conjugated polyene copolymer rubber measured in decalin solvent at a temperature of 135°C. The Mw / Mn values ​​in Table 1 above were determined from polystyrene equivalent values ​​measured by gel permeation chromatography (GPC).

[0064] (2) Polyolefin resin (B)-1: Polypropylene / ethylene random copolymer. Manufactured by Nippon Polypropylene Co., Ltd., product name "Wintec WMX03". Temperature cooling DSC compliant with ISO 11357-3:2018. Taking the heat generation during measurement as 100%, the temperature at which it reaches 95% when accumulated from the highest temperature side is 84°C. (B)-2: Polypropylene / ethylene / 1-butene random copolymer. Manufactured by Nippon Polypropylene Co., Ltd., product name "Novatec FX4E". In a cooling DSC measurement compliant with ISO 11357-3:2018, the exothermic value is set to 100%, and the temperature at which it reaches 95% when accumulated from the high temperature side is 94°C. • (B)-3: Polypropylene / ethylene random copolymer. Manufactured by Nippon Polypropylene Co., Ltd., product name "Novatec FL02A". In the cooling DSC measurement compliant with ISO 11357-3:2018, the exothermic value is set to 100%, and the temperature at which it reaches 95% when accumulated from the high temperature side is 95°C. (B)-4: Polypropylene polymer. Manufactured by Nippon Polypropylene Co., Ltd., product name "Novatec MA3". In a cooling DSC measurement compliant with ISO 11357-3:2018, the exothermic value is set to 100%, and the temperature at which it reaches 95% when accumulated from the high-temperature side is 108°C.

[0065] (3) Mineral oil-based softeners (C): Manufactured by Idemitsu Kosan Co., Ltd., product name "Diana Process Oil PW380"

[0066] (4) Organic peroxides (crosslinking agents) (D): 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, manufactured by NOF Corporation, product name "Perhexa 25B-40"

[0067] (5) Crosslinking agent • (E)-1: Bis(3-ethyl-5-methyl-4-maleimidophenyl)methane, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., product name "BMI-5100" • (E)-2: Divinylbenzene, manufactured by Sankyo Chemical Co., Ltd., product name "Divinylbenzene (purity 55 wt%)"

[0068] (6) Amorphous polyolefin resin (F): Propylene / 1-butene amorphous copolymer, manufactured by Evonik, trade name "VESTPLAST508". The endothermic value of the peak observed by the method described later is 1.9 J·g -1 That is the case.

[0069] (7) Anti-aging agents Pentaerythritol tetrakis(3-(3,5-ditert-butyl-4-hydroxyphenyl)propionate), manufactured by BASF Japan, product name "Irganox 1010"

[0070] 3.2. Example 1 3.2.1. Manufacture of Thermoplastic Elastomer Compositions 67 parts by mass of oil-expanded ethylene-α-olefin-non-conjugated polyene copolymer rubber OSR-1, 23 parts by mass of polyolefin resin (B)-1, 10 parts by mass of additional mineral oil-based softener (C), 0.8 parts by mass of crosslinking aid (E)-1, and 0.1 parts by mass of antioxidant were placed in a 10-liter double-arm pressurized kneader (manufactured by Nippon Spindle Co., Ltd.) heated to 150°C and kneaded at 40 rpm for 20 minutes. The molten composition was then pelletized using a feeder-luder (manufactured by Nippon Spindle Co., Ltd.) set to 180°C and 40 rpm. The obtained pelletized material was mixed with 1.2 parts by mass of organic peroxide (D) and mixed in a Henschel mixer for 30 seconds. The mixture was then extruded using a twin-screw extruder (manufactured by Kobe Steel, model "HYPERKTX 30", with fully meshed coaxial screws and a ratio of L / D (screw flight length L to screw diameter D) of 74) while undergoing a melt-kneading treatment at 230°C and 500 rpm for 2 minutes to obtain a pelletized thermoplastic elastomer composition.

[0071] 3.2.2. Evaluation Method The shear viscosity and DSC measurements of the obtained pelletized thermoplastic elastomer composition, as well as the DSC measurements of components (B) and (F), were performed using the method described below, and each item was evaluated.

[0072] (1) Shear viscosity measurement Using a capillary rheometer (Rosand, product name "RH10"), the shear rate at 140°C was measured at 10s. -1 from 100,000s -1 From the plot of viscosity against shear rate obtained by continuously changing it up to 10,000 s -1 The viscosity was calculated. In this calculation, the plotted shear rate and shear viscosity were those that had undergone Rabinovitch correction and Bergray correction.

[0073] (2)DSC measurement The analysis was conducted in accordance with ISO 11357-3:2018, using a differential scanning calorimeter (NETZSCH DSC, product name "204F1Phoenix"). • Exothermic peak temperature in cold DSC measurement of thermoplastic elastomer composition: The temperature at which the exothermic peak peaks are observed when a composition heated and melted at 200°C is cooled to -80°C at a rate of 10°C / min was defined as the peak temperature. • Heat absorption in temperature rise measurement of thermoplastic elastomer composition: After the temperature fall measurement of the above thermoplastic elastomer composition, the composition was cooled to -80°C and then further heated to 200°C at a rate of 10°C / min. The endothermic peak area observed was defined as the heat absorption. The exothermic peak area observed when component (B), which was heated and melted at 200°C, was cooled to -80°C at a rate of 10°C / min was taken as the 100% exothermic amount when the exothermic peak area was observed when this exothermic amount was accumulated from the high-temperature side to 95%. • Endothermic amount of component (F) in temperature-controlled DSC: The endothermic peak area, confirmed by the same method as the endothermic amount in the temperature-controlled measurement of the thermoplastic elastomer composition described above, was defined as the endothermic amount.

[0074] Next, the obtained pellet-shaped thermoplastic elastomer composition was injection-molded into a 120mm x 120mm x 2mm (length x width x thickness) flat plate using an injection molding machine with a clamping force of 110 tons (manufactured by Japan Steel Works, product name "J-110AD") to obtain test specimens. The hardness, compression set, tensile strength, maximum elongation, and molded appearance of the obtained test specimens were evaluated.

[0075] (3) Hardness (Duro A) Measurements were taken in accordance with JIS K6253-3:2012 (Duro-A).

[0076] (4) Compression set As an indicator of elastic recovery, the compression set was measured after compressing the material by 25% at 70°C for 22 hours, in accordance with JIS K6262:2013. A smaller compression set value indicates better elastic recovery.

[0077] (5) Tensile test In accordance with JIS K6251:2017, tensile strength (T B), maximum growth (E B ) was measured.

[0078] (6) Molded appearance The shrinkage, burning, and mold transfer properties of the test specimens obtained above were evaluated in the following two stages. (Evaluation Criteria) A: There is no sink mark, burning, or skin layer detachment, resulting in an excellent molded appearance. B: One of the following phenomena has occurred: shrinkage, burning, or delamination of the skin layer, resulting in a poor molded appearance.

[0079] 3.3. Examples 2-4, Comparative Examples 1-5 Pellet-shaped thermoplastic elastomer compositions and test specimens were prepared in the same manner as in Example 1, using the proportions shown in Table 2 below, and evaluated in the same manner as in Example 1.

[0080] 3.4. Evaluation Results Table 2 below shows the composition of the thermoplastic elastomer compositions for each example and comparative example, as well as the evaluation results.

[0081] [Table 2]

[0082] Based on the evaluation results in Table 2 above, the thermoplastic elastomer compositions of Examples 1-4 are compared to Comparative Examples 1-5. It was found that this thermoplastic elastomer composition has lower shear viscosity and superior fluidity, and also produces molded products with a better appearance.

[0083] The present invention is not limited to the embodiments described above, and various modifications are possible. The present invention encompasses configurations that are substantially identical to those described in the embodiments (for example, configurations with the same function, method, and result, or configurations with the same purpose and effect). The present invention also encompasses configurations in which non-essential parts of the configurations described in the embodiments are replaced with other configurations. Furthermore, the present invention also encompasses configurations that produce the same effects or achieve the same purpose as the configurations described in the embodiments. Furthermore, the present invention also encompasses configurations that add known technology to the configurations described in the embodiments.

Claims

1. A composition obtained by melt-kneading an ethylene-α-olefin-non-conjugated polyene copolymer rubber (A), which is a copolymer of ethylene, an α-olefin having 3 to 20 carbon atoms, and a non-conjugated polyene, a polyolefin resin (B), and a mineral oil-based softener (C) in the presence of an organic peroxide (D) and a crosslinking aid (E), 140℃, 10,000s －１ The shear viscosity in is 5 to 20 Pa·s. When the polyolefin resin (B) is cooled from 200°C to -80°C at a rate of -10°C / min in accordance with ISO 11357-3:2018 and differential scanning calorimetry is performed, the sum of the observed peak heat generation is taken as 100%, and the temperature at which the accumulated peaks reach 95% when the sum of the observed peaks is 75-94°C. A thermoplastic elastomer composition in which the mass ratio (C) / (A) of the mineral oil-based softener (C) to the ethylene-α-olefin-non-conjugated polyene copolymer rubber (A) is in the range of 1.0 to 1.

9.

2. The thermoplastic elastomer composition according to claim 1, wherein, when differential scanning calorimetry is performed by cooling from 200°C to -80°C at a rate of -10°C / min in accordance with ISO 11357-3:2018, an exothermic peak is observed at 70 to 85°C.

3. In accordance with ISO 11357-3:2018, the peak endothermic value observed when differential scanning calorimetry is performed while the temperature is increased from -80°C to 200°C at a rate of 10°C / min is 1 to 25 J·g. －１ The thermoplastic elastomer composition according to claim 1.

4. In accordance with ISO 11357-3:2018, the peak endothermic value observed when differential scanning calorimetry was performed while the temperature was increased from -80°C to 200°C at a rate of 10°C / min was 10.5 J·g. －１ The thermoplastic elastomer composition according to claim 1, further comprising the amorphous polyolefin resin (F) described below.

5. Automotive weatherstrip using at least a portion of the thermoplastic elastomer composition according to any one of claims 1 to 4.

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