Thermoplastic elastomer composition and method for producing the same, molded article, and weatherstrip for vehicle

Abstract

To provide a method for producing a thermoplastic elastomer composition with superior moldability and wear resistance.SOLUTION: The present invention provides a method for producing a thermoplastic elastomer composition, comprising an addition step of adding 1 to 10 pts.mass of silicone oil to a thermoplastic elastomer to provide a thermoplastic elastomer composition. In the addition step, the silicone oil used includes a first silicone oil having a kinematic viscosity of 100 to 500 mm2 / s, a second silicone oil having a kinematic viscosity of 500 to 5,000 mm2 / s, and a third silicone oil having a kinematic viscosity of 5,000 to 10,000 mm2 / s. The mass ratio of the first silicone oil to the second silicone oil is adjusted to 0.1 to 5, and the mass ratio of the third silicone oil to the second silicone oil is adjusted to 0.1 or more and 5 or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a thermoplastic elastomer composition and a method for producing the same, as well as a molded article obtained by molding the thermoplastic elastomer composition, and a weather strip for vehicles. [Background technology]

[0002] Molded articles obtained by molding a thermoplastic elastomer composition are widely used, for example, as weather strips for vehicles, industrial machine parts, building materials, etc. Related prior art documents include Patent Documents 1 and 2. For example, Patent Document 1 discloses a thermoplastic elastomer composition containing a thermoplastic elastomer obtained by crosslinking high-density polyethylene and a silicone compound. Patent Document 1 describes that the sliding properties of vehicle weather strips can be improved by adding a silicone compound to the thermoplastic elastomer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2021-130788 A [Patent Document 2] JP 2019-001888 A Summary of the Invention [Problem to be solved by the invention]

[0004] For example, a door seal, which is a type of weather strip for vehicles, is attached to a vehicle door and forms a sealed state between the periphery of the opening of the vehicle body and the door. Since the door is a movable member, it is frequently opened and closed. For this reason, the door seal is required to have excellent long-term wear resistance (abrasion resistance). According to the findings of the present inventor, the wear resistance of the door seal can be increased by adding a silicone compound with high viscosity, such as silicone gum, to a thermoplastic elastomer. However, on the other hand, if a silicone compound with high viscosity is used in large amounts, the kneadability of the composition decreases, and it may be difficult to mix depending on the type of extruder or kneader, or the flowability may decrease during molding, making it difficult to mold.

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a thermoplastic elastomer composition excellent in moldability and abrasion resistance, a method for producing the same, a molded article, and a weather strip for vehicles. [Means for solving the problem]

[0006] The present invention includes the following [1] to

[13] . [1]: A method for producing a thermoplastic elastomer, comprising: a crosslinking step of crosslinking the rubber while melt-kneading a raw material composition containing a thermoplastic resin, a rubber, a mineral oil, and a crosslinking agent to obtain a thermoplastic elastomer; and an addition step of adding a silicone oil to the thermoplastic elastomer to obtain a thermoplastic elastomer composition, wherein in the addition step, the blending ratio of the silicone oil to 100 parts by mass of the thermoplastic elastomer is 1 part by mass or more and 10 parts by mass or less, and the silicone oil has a kinetic viscosity of 100 mm at 25° C. 2 / s or more 500mm 2 A first silicone oil having a kinetic viscosity of 500 mm / s or less and 2 / s exceeds 5,000 mm 2 / s or less, and a second silicone oil having a kinematic viscosity of 5,000 mm 2 / s exceeds 10,000 mm 2a third silicone oil having a mass ratio M1 of the first silicone oil to a mass M2 of the second silicone oil (M1 / M2) of 0.1 or more and 5 or less, and a ratio M3 of the third silicone oil to the mass M2 of the second silicone oil (M3 / M2) of 0.1 or more and 5 or less. [2]: The manufacturing method described in [1], wherein in the adding step, the blending ratio of the silicone oil per 100 parts by mass of the thermoplastic elastomer is 1 part by mass or more and 6 parts by mass or less. [3]: The manufacturing method described in [1], wherein the ratio (M1 / M2) of the mass M1 of the first silicone oil to the mass M2 of the second silicone oil is 1 or more and 3 or less, and the ratio (M3 / M2) of the mass M3 of the third silicone oil to the mass M2 of the second silicone oil is 1 or more and 4 or less. [4]: The manufacturing method described in [3], wherein the ratio (M3 / M2) of the mass M3 of the third silicone oil to the mass M2 of the second silicone oil is 1 or more and 3 or less. [5]: The manufacturing method described in [1], wherein the first silicone oil, the second silicone oil, and the third silicone oil are the same type of compound. [6]: A thermoplastic elastomer composition obtained by the production method according to any one of [1] to [5]. [7]: A molded article obtained by molding the thermoplastic elastomer composition according to [6]. [8]: A weather strip for a vehicle, comprising the molded article according to [7]. [9]: A thermoplastic elastomer composition comprising a thermoplastic elastomer formed by dynamically crosslinking a thermoplastic resin, a rubber, a mineral oil, and a crosslinking agent, and a silicone oil, wherein the blending ratio of the silicone oil to 100 parts by mass of the thermoplastic elastomer is 1 part by mass or more and 10 parts by mass or less, wherein the silicone oil comprises a first silicone oil having a molecular weight of 6,610 or more and 19,080 or less, a second silicone oil having a molecular weight of more than 19,080 and 48,150 or less, and a third silicone oil having a molecular weight of more than 48,150 and 59,490 or less, wherein the ratio (M1 / M2) of the mass M1 of the first silicone oil to the mass M2 of the second silicone oil is 0.1 or more and 5 or less, and the ratio (M3 / M2) of the mass M3 of the third silicone oil to the mass M2 of the second silicone oil is 0.1 or more and 5 or less.

[10] : The ratio (M1 / M2) of the mass M1 of the first silicone oil to the mass M2 of the second silicone oil is 1 or more and 3 or less; The thermoplastic elastomer composition according to [9], wherein the ratio (M3 / M2) of the mass M3 of the third silicone oil to the mass M2 of the second silicone oil is 1 or more and 4 or less.

[11] : The thermoplastic elastomer composition according to [9] or

[10] , wherein the first silicone oil, the second silicone oil, and the third silicone oil are all dimethylsilicone oils.

[12] : A molded article obtained by molding the thermoplastic elastomer composition according to [9] or

[10] .

[13] : A weather strip for a vehicle, comprising the molded article according to

[12] .

[0007] As a result of intensive research, the present inventors have found that the above-mentioned problems can be solved by blending first to third silicone oils having mutually different kinetic viscosities (or molecular weights) in a predetermined mixing ratio. Further research led to the completion of the present invention. The thermoplastic elastomer composition disclosed herein ensures appropriate melt fluidity and achieves excellent moldability. In addition, it is possible to realize a molded article and a weather strip for a vehicle that are resistant to wear and have excellent abrasion resistance even when used for a long period of time. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a flow chart of a manufacturing method according to one embodiment. [Diagram 2] FIG. 2 is a perspective view of a vehicle equipped with a door seal. [Diagram 3] FIG. 3 is a front view of the door seal of FIG. [Figure 4] FIG. 4 is a perspective view showing the wear resistance evaluation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. It should be noted that the embodiments described here are not intended to limit the present invention. Also, the same reference numerals are used for members and parts that perform the same function, and duplicated descriptions may be omitted or simplified as appropriate. In this specification, the expression "X to Y" (X and Y are arbitrary numerical values) indicating a range includes the meaning of "greater than X" and "smaller than Y" as well as the meaning of "X or more and Y or less."

[0010] <Method of producing thermoplastic elastomer composition> Fig. 1 is a flow chart of a method for producing a thermoplastic elastomer composition according to one embodiment. As shown in Fig. 1, the method for producing the thermoplastic elastomer composition according to this embodiment includes a crosslinking step S10 and an adding step S20. The method for producing the thermoplastic elastomer composition according to this embodiment may include other steps as necessary.

[0011] The crosslinking step S10 is a step of crosslinking the rubber (B) while melt-kneading a raw material composition containing a thermoplastic resin (A), a rubber (B), a mineral oil (C), and a crosslinking agent (D) to obtain a thermoplastic elastomer. This step may be the same as in the past. In the embodiment of FIG. 1, the thermoplastic resin (A) and the rubber (B) are first mixed, and then the mineral oil (C) and the crosslinking agent (D) are added in sequence to prepare the raw material composition, but the order of adding each raw material may be changed as appropriate. In addition, the types and blending ratios of various raw material components contained in the raw material composition may be appropriately adjusted in the same manner as in the past, depending on, for example, the application or usage mode of the thermoplastic elastomer composition. The raw material composition may further contain any component such as an additive (E).

[0012] The thermoplastic resin (A) is a component that is melt-kneaded with the rubber (B). As the thermoplastic resin (A), one or more compounds that have been used in the thermoplastic elastomer composition according to the application of the composition can be appropriately used. Specific examples include homopolymers or copolymers of polypropylene (PP), polyethylene (PE), ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 4-methyl-1-pentene, and 3-methyl-1-pentene. Among them, polypropylene is preferred for applications such as vehicle weather strips.

[0013] Although not particularly limited, when the total of the thermoplastic resin (A), rubber (B), and mineral oil (C) is 100 mass%, the blending ratio of the thermoplastic resin (A) (the total when two or more types are used) is approximately 1 to 40 mass%, preferably 5 to 30 mass%, and more preferably 10 to 20 mass%.

[0014] The rubber (B) is a component to be dynamically crosslinked. As the rubber (B), one or more compounds that have been used in this type of composition can be appropriately used depending on the type of the thermoplastic resin (A), for example. Specific examples include ethylene propylene rubber (EPM), ethylene propylene diene rubber (EPDM), natural rubber (e.g., NR), diene rubber (e.g., SBR, NBR), acrylic rubber (e.g., ACM, ANM), and water additives thereof. For example, when the thermoplastic resin (A) contains polypropylene, ethylene propylene diene rubber is preferred.

[0015] Although not particularly limited, when the total of the thermoplastic resin (A), the rubber (B) and the mineral oil (C) is taken as 100 mass%, the mixing ratio of the rubber (B) is about 20 to 70 mass%, preferably 30 to 60 mass%, and more preferably 40 to 50 mass%. In some embodiments, the rubber (B) is preferably the first component (the component having the highest mixing ratio by mass ratio; the same applies below) or the second component (the component having the second highest mixing ratio by mass ratio; the same applies below) of the raw material composition.

[0016] The mineral oil (C) is a component (softener) that weakens the intermolecular action of rubber, facilitates processing, and improves the flexibility and elasticity of the resulting molded product. As the mineral oil (C), one or more compounds that have been used in this type of composition can be used as appropriate. Specific examples include high-boiling petroleum fractions such as paraffinic process oil, naphthenic process oil, and aromatic process oil.

[0017] Although not particularly limited, when the total of the thermoplastic resin (A), the rubber (B) and the mineral oil (C) is taken as 100 mass%, the blending ratio of the mineral oil (C) is about 20 to 70 mass%, preferably 30 to 60 mass%, and more preferably 40 to 50 mass%. In some embodiments, the mineral oil (C) is preferably the first or second component of the raw material composition. Also, in some embodiments, the blending ratio of the mineral oil (C) is preferably approximately the same as that of the rubber (B) (within ±5 mass%).

[0018] The crosslinking agent (D) is a component that causes a dynamic crosslinking reaction in the rubber (B) by heating. As the crosslinking agent (D), one or more compounds that have been used in this type of composition can be appropriately used depending on, for example, the type of rubber (B). Specific examples include organic peroxides, sulfur, sulfur compounds, quinoid compounds, phenolic resins, etc. Among them, organic peroxides are preferable. Examples of organic peroxides include dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexyne-3, 1,3-bis(tert-butylperoxyisopropyl)benzene, benzoyl peroxide, tert-butyl peroxybenzoate, diacetyl peroxide, lauroyl peroxide, etc.

[0019] Although not particularly limited, the mixing ratio of the crosslinking agent (D) is generally 0.2 to 5 parts by mass, preferably 0.5 to 2 parts by mass, when the total of the thermoplastic resin (A), the rubber (B), and the mineral oil (C) is 100 parts by mass.

[0020] As the additive (E), one or more of compounds conventionally used in this type of composition can be appropriately used. Specific examples include crosslinking assistants, lubricants (e.g., silicone-based lubricants), antioxidants, inorganic fillers (e.g., carbon black), bulking agents, softeners (plasticizers) other than mineral oils, defoamers, foaming agents, stabilizers (e.g., heat stabilizers, antiaging agents, light stabilizers, ultraviolet absorbers, etc.), colorants, pigments, etc. Additives are blended according to the purpose within a range that does not impair the characteristics of the present invention. By including a crosslinking assistant, it becomes easier to adjust the crosslinking reaction rate. By including an inorganic filler (e.g., carbon black), it is possible to improve the reinforcing properties and mechanical properties (e.g., strength) of the thermoplastic elastomer composition. Carbon black is preferably added as a master batch (MB). When additive (E) is contained, the total blending ratio thereof is approximately 0.01 to 15 parts by mass, preferably approximately 0.1 to 10 parts by mass, per 100 parts by mass of the total of thermoplastic resin (A), rubber (B), and mineral oil (C).

[0021] The method of heating the raw material composition to melt-knead is not particularly limited and may be the same as in the past. For example, it can be performed using a conventional kneading device such as an extruder such as a single screw extruder or a twin screw extruder, or a kneader or a continuous mixer. The melt-kneading conditions (for example, kneading temperature, kneading atmosphere, shear force during kneading, kneading time) may be the same as in the past, and may be appropriately adjusted so that the rubber (B) is appropriately crosslinked. The kneading temperature may be set to be equal to or higher than the melting point of the thermoplastic resin (A), and is usually 150 to 300°C, preferably 180 to 250°C. In this manner, a dynamically crosslinked thermoplastic elastomer can be obtained.

[0022] The adding step S20 is a step of adding silicone oil to the thermoplastic elastomer obtained in the crosslinking step S10 to obtain a thermoplastic elastomer composition. In this embodiment, it is necessary to use at least three types of silicone oil having different kinetic viscosities. 2 / s or more 500mm 2 A first silicone oil having a kinetic viscosity of 500 mm / s or less and 2 / s exceeds 5,000 mm 2 / s or less, and a second silicone oil having a kinematic viscosity of 5,000 mm 2 / s exceeds 10,000 mm 2 It is necessary to use a third silicone oil having a viscosity of 1 / s or less. It is recommended that the three types of silicone oils be mixed in advance and then added to the thermoplastic elastomer. In this specification, the "kinematic viscosity" refers to a value measured at 25°C using an Ubbelohde viscometer specified in ASTM D 445-46T.

[0023] The total amount of the first to third silicone oils is preferably 80% by mass or more when the total silicone oil is taken as 100% by mass, and it is particularly preferable that the first to third silicone oils are substantially composed of the first to third silicone oils (95% by mass or more of the total silicone oil). 2 It is more preferable that the silicone oil does not substantially contain high-viscosity silicone oil or silicone gum having a kinematic viscosity exceeding 1 / s (for example, 1 mass % or less of the total silicone oil). However, the silicone oil may further contain a fourth silicone oil that does not satisfy the above kinematic viscosity range, as long as it does not significantly reduce the effect of the technology disclosed herein.

[0024] In addition, the first to third silicone oils must be blended at a predetermined mixing ratio. Specifically, the ratio (M1 / M2) of the mass M1 of the first silicone oil to the mass M2 of the second silicone oil must be 0.1 to 5, and the ratio (M3 / M2) of the mass M3 of the third silicone oil to the mass M2 of the second silicone oil must be 0.1 to 5. By blending the first to third silicone oils at the above mixing ratio, the melt flowability of the thermoplastic elastomer composition is ensured, and excellent moldability can be achieved. In addition, compared to, for example, using the second silicone oil alone or using a mixture of the first silicone oil and the third silicone oil (only two types), the molded product is less likely to wear out even after long-term use, and a molded product with relatively excellent wear resistance can be achieved.

[0025] From the viewpoint of further improving the abrasion resistance, the mass ratio (M1 / M2) is preferably 1 to 3, for example, 2 to 3. Moreover, from the viewpoint of achieving a high level of balance between the abrasion resistance and the melt fluidity, the mass ratio (M3 / M2) is preferably 1 to 4, more preferably 1 to 3, for example, 2 to 3.

[0026] As the first to third silicone oils, one or more of compounds conventionally used in this type of composition can be appropriately used as long as they have the above-mentioned kinetic viscosity. Specific examples include dimethyl silicone oil, phenylmethyl silicone oil, diphenyl silicone oil, alkyl silicone oil, fluorosilicone oil, tetramethyltetraphenyltrisiloxane, and modified silicone oils thereof. The first to third silicone oils are preferably the same type of compound. The first to third silicone oils are preferably dimethyl silicone oil (a chain-like dimethyl polysiloxane having a trimethylsilyl group at the end). However, the first to third silicone oils may be different compounds from each other as long as they do not significantly reduce the effect of the technology disclosed herein.

[0027] It is generally known that there is a correlation between the kinetic viscosity and molecular weight of silicone oil. For example, if the kinetic viscosity of silicone oil is 100 mm 2 / s or more, the relationship between the kinetic viscosity and molecular weight of silicone oil is expressed by AJ Barry's formula: log η cs / 25℃ =1.00+0.0123M 0.5 (However, η cs / 25℃ is the kinetic viscosity at 25°C (cs=mm 2 / s), where M is a molecular weight of 2,500 or more; ); (J. Appl. Physics. 17. 1020

[1946] ).

[0028] Therefore, in some embodiments, according to the AJ Barry formula, the molecular weight of the first silicone oil is preferably about 6,610 or more and 19,080 or less, the molecular weight of the second silicone oil is preferably about more than 19,080 and 48,150 or less, and the molecular weight of the third silicone oil is preferably about more than 48,150 and 59,490 or less, corresponding to the above range of kinetic viscosity. Note that, as the "molecular weight", the value in the manufacturer's catalogue can be adopted. In addition, the weight average molecular weight measured by gel permeation chromatography (GPC) and calculated in terms of standard polystyrene can also be adopted.

[0029] The blending ratio of the silicone oil (total of multiple types) needs to be 1 to 10 parts by mass per 100 parts by mass of the thermoplastic elastomer. This allows the effects of the technology disclosed herein to be properly exhibited. From the viewpoint of balancing abrasion resistance and melt fluidity at a high level, the blending ratio of the silicone oil is preferably 1.2 parts by mass or more, more preferably 2.4 parts by mass or more, even more preferably 3 parts by mass or more, and particularly preferably 5 parts by mass or more. In addition, from the viewpoint of improving melt fluidity and processability, and from the viewpoint of suppressing peeling phenomenon of the molded body to reduce appearance defects, the blending ratio is preferably 8 parts by mass or less, more preferably 6 parts by mass or less.

[0030] In some embodiments, the blending ratio of the second silicone oil is 0.5 parts by mass or more, for example, 0.5 to 3 parts by mass is preferable, more preferably 0.7 to 1.5 parts by mass, and particularly preferably 1±0.2 parts by mass, relative to 100 parts by mass of the thermoplastic elastomer. By setting the blending ratio of the second silicone oil to a predetermined value or more, the compatibility between the first silicone oil and the third silicone oil, which have a large viscosity difference, can be improved, and the kneading property can be improved. By setting the blending ratio of the second silicone oil to a predetermined value or less, the blending ratio of the first silicone oil and the third silicone oil increases, and the wear resistance can be improved.

[0031] The shape of the thermoplastic elastomer composition is not particularly limited. The thermoplastic elastomer composition can be in the form of powder, pellets, sheets, etc., depending on the application. For example, the thermoplastic elastomer composition can be extruded by an extruder, cooled in cold water, and cut into cylindrical or rice grain shapes by a cutter to obtain a pellet form. In this manner, the thermoplastic elastomer composition disclosed herein can be obtained.

[0032] <Thermoplastic elastomer composition> The thermoplastic elastomer composition of the present embodiment is obtained by the above-mentioned manufacturing method. In some embodiments, the thermoplastic elastomer composition includes a thermoplastic elastomer obtained by dynamically crosslinking a thermoplastic resin, a rubber, a mineral oil, and a crosslinking agent, and a silicone oil. In some embodiments, the silicone oil includes at least three types of silicone oils having different molecular weights. Specifically, the silicone oil includes a first silicone oil having a molecular weight of 6,610 or more and 19,080 or less, a second silicone oil having a molecular weight of more than 19,080 and 48,150 or less, and a third silicone oil having a molecular weight of more than 48,150 and 59,490 or less.

[0033] The fact that the silicone oil contains at least three types of silicone oil with different molecular weights can be confirmed by the fact that a molecular weight distribution curve (horizontal axis: molecular weight in standard polystyrene equivalent, vertical axis: detection intensity of a differential refractive index detector) obtained by gel permeation chromatography analysis has at least one peak (maximum value) in each of the following regions: a first region (A1) having a molecular weight of 6,610 or more and 19,080 or less, a second region (A2) having a molecular weight of more than 19,080 and 48,150 or less, and a third region (A3) having a molecular weight of more than 48,150 and 59,490 or less.

[0034] The ratio (M1 / M2) of the mass M1 of the first silicone oil to the mass M2 of the second silicone oil is preferably 0.1 to 5, and the ratio (M3 / M2) of the mass M3 of the third silicone oil to the mass M2 of the second silicone oil is preferably 0.1 to 5. In some embodiments, the mass ratio (M1 / M2) is preferably 1 to 3, for example, 2 to 3. The mass ratio (M3 / M2) is preferably 1 to 4, more preferably 1 to 3, for example, 2 to 3. This allows a high level of balance between wear resistance and melt fluidity.

[0035] The mass ratio (M1 / M2) can be confirmed as the ratio (H1 / H2) when the detection intensity of the maximum peak in the first region (A1) is H1 and the detection intensity of the maximum peak in the second region (A2) is H2 in the above-mentioned molecular weight distribution curve. Similarly, the mass ratio (M3 / M2) can be confirmed as the ratio (H3 / H2) when the detection intensity of the maximum peak in the second region (A2) is H2 and the detection intensity of the maximum peak in the third region (A3) is H3 in the above-mentioned molecular weight distribution curve.

[0036] The first to third silicone oils are more preferably dimethyl silicone oils. The blending ratio of the silicone oils (total of multiple types) is preferably 1 to 10 parts by mass, and more preferably 6 parts by mass or less, per 100 parts by mass of the thermoplastic elastomer.

[0037] <Molded body> The molded article of the present embodiment is obtained by molding the above-mentioned thermoplastic elastomer composition. The method for obtaining a molded article from the thermoplastic elastomer composition is not particularly limited and may be the same as the conventional method. For example, the molded article can be produced by injection molding, extrusion molding, press molding, blow molding, etc., using a molding machine used in a conventionally known resin processing method. For example, in injection molding, the thermoplastic elastomer composition is heated and melted in an injection molding machine, and then injected into a mold from the nozzle tip to produce a molded article. In this case, the cylinder temperature is usually 150 to 300°C, preferably 180 to 250°C. The mold temperature is usually 50°C or less, preferably 20 to 40°C.

[0038] The molded article of the present embodiment can be widely used, for example, as a weather strip for a vehicle, an industrial machine part, a building material, and the like. In particular, since it has excellent abrasion resistance, it can be suitably used as a weather strip for a vehicle. In this specification, the term "weather strip for a vehicle" refers to a general sealing part that is attached to a door part (e.g., a back door part, a front door part, a rear door part), a trunk part, a sunroof part, and the like of a vehicle to prevent wind, rain, dust, noise, and the like from entering the inside of the vehicle from the outside, and is a term that includes, for example, a door seal attached to a door as a movable member, a door opening seal attached to a vehicle body as a fixed member, and a luggage seal attached to a trunk.

[0039] FIG. 2 is a perspective view of a vehicle 1 equipped with a door seal 10 according to one embodiment. In FIG. 2, the vehicle 1 includes a vehicle body 2 and a door 4 attached to an opening of the vehicle body 2. The door seal 10 is attached along the outer edge of the door 4. The door seal 10 has a hollow portion (not shown) with a hollow cross section, and the hollow portion comes into contact with the door 4 to seal the gap between the opening of the vehicle body 2 and the door 4, thereby forming a hermetic state. This makes it possible to prevent wind, rain, dust, noise, etc. from entering from the outside, thereby improving the comfort inside the vehicle.

[0040] Fig. 3 is a front view of the door seal 10 of Fig. 2 as seen from the inside of the vehicle. Here, the door seal 10 is annular (ring-shaped). The door seal 10 includes a main body portion 12 having a pair of end portions 12e, and a corner portion 14 that joins the opposing end portions 12e of the main body portion 12. Note that here, the door seal 10 is composed of one main body portion 12 and one corner portion 14, but there may be two or more main body portions 12 and / or corner portions 14.

[0041] The main body portion 12 is a portion that is disposed at least on the side wall portion of the door 4. Here, the main body portion 12 is integrally and continuously molded by extrusion molding. The main body portion 12 is preferably made of a rubber material such as ethylene propylene rubber or diene rubber. In order to improve sealing performance, the main body portion 12 is preferably made of EPDM, for example. The main body portion 12 preferably contains the same type of rubber material as the corner portion 14.

[0042] The corner portion 14 is interposed between a pair of end portions 12e of the main body portion 12. The corner portion 14 is a portion that becomes a joint for joining the main body portion 12. The corner portion 14 is preferably flexible. The corner portion 14 is preferably composed of the molded article disclosed herein. Here, the corner portion 14 is formed integrally with the main body portion 12 by injection molding the above-mentioned thermoplastic elastomer composition.

[0043] Examples of the present invention will be described below, but it is not intended that the present invention be limited to those shown in these examples.

[0044] <Test Example I> First, the following raw materials were added to a twin-screw extruder and mixed to prepare a preliminary mixture. Rubber (EPDM): KEP9570E (KUMHO) 43.7 parts by weight Thermoplastic resin (PP): J106G (Prime Polymer) 9 parts by weight Thermoplastic resin (olefin resin): L-MODU (registered trademark) S400 (manufactured by Idemitsu Kosan Co., Ltd.) 3 parts by weight Antioxidant: Adeka STAB (registered trademark) AO-60 (manufactured by ADEKA Corporation) 0.1 parts by weight Lubricant: Chaline (registered trademark) R-170S (manufactured by Nissin Chemical Co., Ltd.) 1.07 parts by weight Lubricant: Silicone PP / MB: X-22-2101 (Shin-Etsu Silicone Co., Ltd.) 3.2 parts by weight Carbon black / MB: 2.23 parts by weight

[0045] Next, the following mineral oil was added to the preliminary mixture, and further the following crosslinking agent and crosslinking aid were added to prepare a raw material mixture. Then, the raw material mixture was melt-kneaded to dynamically crosslink the rubber. As a result, a pellet-shaped thermoplastic elastomer was obtained (crosslinking step S10). Mineral oil: Diana Process Oil PW-90 (Idemitsu Kosan Co., Ltd.) 46.7 parts by weight Crosslinking agent (organic peroxide): Perhexa (registered trademark) 25B (manufactured by NOF Corporation) 0.72 parts by weight Crosslinking agent: 1.28 parts by weight of divinylbenzene 81% (manufactured by Nippon Steel & Sumitomo Metal Corporation)

[0046] Next, the following three types of silicone oils with different kinetic viscosities were prepared, and one to three of these silicone oils were added to the above thermoplastic elastomer and mixed as shown in Tables 1 and 2 to obtain the thermoplastic elastomer composition of each example (addition step S20). Note that the parts by mass of the silicone oil in the tables are the blending ratio when the thermoplastic elastomer is 100 parts by mass. First silicone oil: KF-96-100cs (Shin-Etsu Silicone Co., Ltd.) Kinematic viscosity (25℃) 100mm 2 / s, molecular weight 6610 Second silicone oil: KF-96-1000cs (Shin-Etsu Silicone Co., Ltd.) Kinematic viscosity (25℃) 1000mm 2 / s, molecular weight 26,440 Third silicone oil: KF-96-10000cs (Shin-Etsu Silicone Co., Ltd.) Kinematic viscosity (25℃) 10000mm 2 / s, molecular weight 59,490

[0047] <Evaluation of Melt Flowability of Thermoplastic Elastomer Composition> The melt fluidity of each thermoplastic elastomer composition was evaluated based on ease of molding. The results are shown in Tables 1 and 2. The evaluation results of melt fluidity in the tables are based on the following indexes. ◎: The raw materials are particularly easy to flow and mold. · 〇: The fluidity is slightly low, but the raw material flows easily under the specified molding conditions and is easy to mold. ×: The raw material is difficult to flow and mold (varies, not integrated)

[0048] <Abrasion resistance evaluation of molded products> The thermoplastic elastomer prepared above was put into an injection molding machine and injection molded at a cylinder temperature of 200°C and a mold temperature of 30°C to prepare a test piece (Φ20mm×120mm molded body) having a hollow cylindrical shape. Next, the flat bottom surface of the obtained test piece was fixed to a jig (not shown), and the test piece was arranged so as to face a rectangular coated plate larger than the test piece, as shown in FIG. 4. Then, the test piece was pressed against the coated plate so as to have the following compression ratio, and the coated plate was vibrated in the long side direction (up and down direction in FIG. 4) under the following conditions. At this time, the wear resistance was evaluated based on the degree of adhesion of the wear powder (wear marks) remaining on the coated plate. · Compression amount of test piece: 10% compression · Test time: about 8 hours · Vibration frequency: 1000 times / min · Number of vibrations: 500,000 times

[0049] The results are shown in Tables 1 and 2. The evaluation results of abrasion resistance in the tables are based on the following index, and it can be said that the smaller the area of ​​the abrasion marks on the coated plate, the more excellent the abrasion resistance. ◎: Wear mark area is 10mm 2 less than ○: Wear mark area is 10mm 2 More than 20mm 2 less than ×: Area of ​​wear mark is 20mm 2 End - Significant wear: Area not measured due to severe wear

[0050] [Table 1]

[0051] [Table 2]

[0052] As shown in Table 2, in Examples 8 to 14, in which one or two types of silicone oil were used, the abrasion resistance was low. In contrast, as shown in Table 1, in Examples 1 to 7, in which three types of silicone oil were used, the abrasion resistance was relatively high. From this, it was found that the effect of the technology disclosed herein is specifically expressed by using three types of silicone oil. Although it is not intended to be particularly limited, it is considered that the reason for this is that the compatibility of the silicone oil as a whole is improved by using three types of silicone oil. These effects show the significance of the technology disclosed herein.

[0053] Among them, the wear resistance was particularly high in Examples 1 to 3 and 5, in which the ratio (M1 / M2) of the mass M1 of the first silicone oil to the mass M2 of the second silicone oil was 1 to 3, and the ratio (M3 / M2) of the mass M3 of the third silicone oil to the mass M2 of the second silicone oil was 1 to 4. Furthermore, in Examples 2, 3 and 5, in which the mass ratio (M3 / M2) was 1 to 3, the wear resistance and melt fluidity were well balanced.

[0054] <Test Example II> Thermoplastic elastomers were prepared and their melt flow properties were evaluated in the same manner as in Example 3 of Test Example I, except that the total blending ratio of silicone oil was changed as shown in Table 3. Molded bodies were also prepared and their abrasion resistance was evaluated. The results are shown in Table 3.

[0055] [Table 3]

[0056] As shown in Table 3, it was found that the effects of the technology disclosed herein can be adequately achieved by setting the silicone oil content to 1 part by mass or more. Among them, Examples 3 and 15 to 17, in which the silicone oil content was 2.4 parts by mass or more, had particularly high melt fluidity. Moreover, Example 3, in which the silicone oil content was 5 parts by mass or more, had particularly high abrasion resistance.

[0057] Although the specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples exemplified above.

[0058] For example, in the above embodiment, only the corner portion 14 is formed from the above thermoplastic elastomer composition, but this is not limited thereto. In another embodiment, in addition to the corner portion 14, the main body portion 12 may also be formed from the above thermoplastic elastomer composition. Also, in the above embodiment, the corner portion 14 is formed integrally with the main body portion 12 by injection molding the above thermoplastic elastomer composition, but this is not limited thereto. In another embodiment, a door seal continuously molded by extrusion molding may be bent at the corner portion and attached to the door 4, and in this case, the entire door seal may be formed from the above thermoplastic elastomer composition. [Explanation of symbols]

[0059] S10 Crosslinking process S20 addition process 1 vehicle 4 Door 10 Door Seal 12 Main body 14 Corner section

Claims

1. a crosslinking step of crosslinking the rubber while melt-kneading a raw material composition containing a thermoplastic resin, a rubber, a mineral oil, and a crosslinking agent to obtain a thermoplastic elastomer; an adding step of adding a silicone oil to the thermoplastic elastomer to obtain a thermoplastic elastomer composition; Including, In the adding step, the blending ratio of the silicone oil to 100 parts by mass of the thermoplastic elastomer is set to 1 part by mass or more and 10 parts by mass or less, The silicone oil has a composition as follows: Dynamic viscosity is 100mm ２ / s or more 500mm ２ / s or less; and Dynamic viscosity is 500 mm ２ / s exceeds 5,000 mm ２ / s or less; and Dynamic viscosity is 5,000 mm ２ / s exceeds 10,000 mm ２ / s or less; and Using a ratio (M1 / M2) of a mass M1 of the first silicone oil to a mass M2 of the second silicone oil is set to 0.1 or more and 5 or less; a ratio (M3 / M2) of a mass M3 of the third silicone oil to a mass M2 of the second silicone oil is 0.1 or more and 5 or less; A method for producing a thermoplastic elastomer composition.

2. In the adding step, the blending ratio of the silicone oil to 100 parts by mass of the thermoplastic elastomer is set to 1 part by mass or more and 6 parts by mass or less. The method of claim 1 .

3. a ratio (M1 / M2) of a mass M1 of the first silicone oil to a mass M2 of the second silicone oil is set to 1 or more and 3 or less; a ratio (M3 / M2) of the mass M3 of the third silicone oil to the mass M2 of the second silicone oil is 1 or more and 4 or less; The method of claim 1 .

4. a ratio (M3 / M2) of the mass M3 of the third silicone oil to the mass M2 of the second silicone oil is set to 1 or more and 3 or less; The method according to claim 3.

5. The first silicone oil, the second silicone oil, and the third silicone oil are the same type of compound. The method of claim 1 .

6. A thermoplastic elastomer composition obtained by the method according to any one of claims 1 to 5.

7. A molded article obtained by molding the thermoplastic elastomer composition according to claim 6.

8. A weather strip for a vehicle, comprising the molded article according to claim 7.

9. A thermoplastic elastomer composition comprising: a thermoplastic elastomer obtained by blending a thermoplastic resin, a rubber, a mineral oil, and a crosslinking agent; and a silicone oil, the blending ratio of the silicone oil being 1 part by mass or more and 10 parts by mass or less per 100 parts by mass of the thermoplastic elastomer, The silicone oil is a first silicone oil having a molecular weight of 6,610 or more and 19,080 or less; a second silicone oil having a molecular weight of more than 19,080 and not more than 48,150; a third silicone oil having a molecular weight of more than 48,150 and not more than 59,490; Including, a ratio (M1 / M2) of a mass M1 of the first silicone oil to a mass M2 of the second silicone oil is 0.1 or more and 5 or less; A ratio (M3 / M2) of a mass M3 of the third silicone oil to a mass M2 of the second silicone oil is 0.1 or more and 5 or less; Thermoplastic elastomer composition.

10. a ratio (M1 / M2) of a mass M1 of the first silicone oil to a mass M2 of the second silicone oil is 1 or more and 3 or less; A ratio (M3 / M2) of the mass M3 of the third silicone oil to the mass M2 of the second silicone oil is 1 or more and 4 or less; The thermoplastic elastomer composition according to claim 9.

11. The first silicone oil, the second silicone oil, and the third silicone oil are all dimethyl silicone oils. The thermoplastic elastomer composition according to claim 9 or 10.

12. A molded article obtained by molding the thermoplastic elastomer composition according to claim 9 or 10.

13. A weather strip for a vehicle, comprising the molded article according to claim 12.

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