Resin composition for a coolant transport pipe for vehicles and coolant transport pipe for vehicles

Abstract

Provided are: a resin composition for a vehicle coolant transport pipe, the resin composition enabling smoothness and physical properties to be ensured by low-temperature extrusion, and a vehicle coolant transport pipe. The resin composition for a vehicle coolant transport pipe comprises the following (A) and (B), wherein the contents of (A) and (B) are 75 to 99 mass% and 1 to 25 mass%, respectively, with respect to the polymer components assumed to be 100 mass%. The vehicle coolant transport pipe is formed from the resin composition for a vehicle coolant transport pipe. (A): a propylene-α-olefin block copolymer having a melt flow index of 0.2 to 1.5 g / 10 min, determined at 230°C and a load of 2.16 kg, (B): a propylene homopolymer having a melt flow index of 2 to 50 g / 10 min, determined at 230°C and a load of 2.16 kg.

Description

Technical area

[0001] The present invention relates to a resin composition for a coolant transport pipe for a vehicle and a coolant transport pipe for a vehicle, and more particularly, to a resin composition for a coolant transport pipe for a vehicle and a coolant transport pipe for a vehicle suitable as a pipe for transporting the coolant in a cooling system of an automobile or the like. State of the art

[0002] Coolant transport pipes are pipes used to transport coolant in the cooling systems of internal combustion vehicles and electric vehicles. Polyamide resin is often used for coolant transport pipes due to its heat resistance. In recent years, a polypropylene-based resin, which offers cost advantages, has been considered as a material for coolant transport pipes. Bibliography Patent Literature 1: Japanese Patent Laid-Open No. 2012-091730 Patent Literature 2: Japanese Patent Laid-Open No. 2006-194318 SUMMARY OF THE INVENTION Problems to be solved by the invention

[0003] Coolant transport pipes are long and have many bends in the pipeline. Therefore, flow resistance is high. If the smoothness of the pipe's inner surface is poor, local stresses can develop, potentially causing cracks. Furthermore, the smoothness of the pipe's inner surface tends to decrease when the temperature during pipe extrusion is low. Conversely, the physical properties of the pipe tend to deteriorate when the temperature during pipe extrusion is high.

[0004] The problem to be solved by the present invention is to provide a resin composition for a coolant transport pipe for a vehicle and a coolant transport pipe for a vehicle that can ensure smoothness in extrusion at low temperatures and physical properties. Means of solving the problem

[0005] A resin composition for a coolant transport pipe for a vehicle according to the present invention contains the following (A) and (B), wherein in 100 mass% of a polymer component, (A) accounts for 75 mass% or more and 99 mass% or less, and (B) accounts for 1 mass% or more and 25 mass% or less. (A) A propylene-α-olefin block copolymer having a melt flow index of 0.2 g / 10 min or more and 1.5 g / 10 min or less, measured at 230°C under a load of 2.16 kg (B) A propylene homopolymer having a melt flow index of 2 g / 10 min or more and 50 g / 10 min or less when measured at 230°C under a load of 2.16 kg.

[0006] A difference between (A) and (B) in melt flow index measured at 230°C under a load of 2.16 kg may be 5 g / 10 min or more. The melt flow index of (B) measured at 230°C under a load of 2.16 kg may be 10 g / 10 min or more and 50 g / 10 min or less. In 100 mass% of the polymer component, (A) may account for 90 mass% or more and 97 mass% or less, and (B) may account for 3 mass% or more and 10 mass% or less. (A) may be an ethylene-propylene block copolymer.

[0007] Furthermore, a coolant transport pipe for a vehicle according to the present invention includes the above-mentioned resin composition for the coolant transport pipe for a vehicle.

[0008] (B) may occur more in an outer part than in an inner part in the radial direction of the coolant transport pipe for a vehicle. (1) A resin composition for a coolant transport pipe for a vehicle according to the present invention contains the following (A) and (B), wherein, in 100 mass % of a polymer component, (A) accounts for 75 mass % or more and 99 mass % or less, and (B) accounts for 1 mass % or more and 25 mass % or less. (A) A propylene-α-olefin block copolymer having a melt flow index of 0.2 g / 10 min or more and 1.5 g / 10 min or less, measured at 230°C under a load of 2.16 kg (B) A propylene homopolymer having a melt flow index of 2 g / 10 min or more and 50 g / 10 min or less when measured at 230°C under a load of 2.16 kg. (2) In (1) above, a difference between (A) and (B) in melt flow index measured at 230 °C under a load of 2.16 kg may be 5 g / 10 min or more. (3) In (1) or (2) above, the melt flow index of (B) measured at 230°C under a load of 2.16 kg may be 10 g / 10 min or more and 50 g / 10 min or less. (4) In any one of (1) to (3) above, (A) may be 90 mass% or more and 97 mass% or less in 100 mass% of the polymer component, and (B) may be 3 mass% or more and 10 mass% or less. (5) In any one of (1) to (4) above, (A) may be an ethylene-propylene block copolymer. (6) A coolant transport pipe for a vehicle according to the present invention includes the resin composition for the coolant transport pipe for a vehicle according to any one of (1) to (5) above. (7) In (6) above, (B) in the radial direction of the coolant transport pipe for a vehicle may occur more in an outer part than in an inner part. Effects of the invention

[0009] The resin composition for a vehicle coolant transfer pipe according to the present invention, as described above, can ensure both smoothness and physical properties upon low-temperature extrusion by blending a high-viscosity block polypropylene and a low-viscosity homopolypropylene in a specific ratio. This can achieve both the physical properties of the pipe and the smoothness of the pipe's inner surface.

[0010] Here, when the difference between (A) and (B) in melt flow index measured at 230°C under a load of 2.16 kg is 5 g / 10 min or more, (B) tends to appear on the pipe surface, which improves the smoothness of the pipe inner surface.

[0011] In addition, the resin composition is characterized by the effect of improving the smoothness in low-temperature extrusion when the melt flow index measured at 230°C under a load of 2.16 kg is 10 g / 10 min or more and 50 g / 10 min or less.

[0012] In addition, both the effect of improving smoothness and physical properties at low temperature extrusion can be achieved at a high level when (A) accounts for 90 mass% or more and 97 mass% or less and (B) accounts for 3 mass% or more and 10 mass% or less in 100 mass% of a polymer component.

[0013] In addition, the resin composition is characterized by the effect of achieving both the physical properties of the pipe and the smoothness of the pipe inner surface when (A) is an ethylene-propylene block copolymer.

[0014] Furthermore, the vehicle coolant transfer pipe according to the present invention includes the above-mentioned resin composition for the vehicle coolant transfer pipe. Therefore, smoothness and physical properties can be ensured during extrusion at low temperatures. This makes it possible to achieve both the physical properties of the pipe and the smoothness of the pipe's inner surface. Furthermore, the coolant transfer pipe is long and has many angled sections in the pipe. Therefore, the coolant transfer pipe can excel in bending processability.

[0015] In addition, the coolant transport pipe is characterized by the effect of improving the smoothness of the inner pipe surface when (B) in the radial direction of the coolant transport pipe for a vehicle occurs more in the outer part than in the inner part. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a configuration diagram showing a coolant transport pipe for a vehicle according to an embodiment of the present invention. DESCRIPTION OF EMBODIMENTS

[0016] A resin composition for a coolant transport pipe for a vehicle and a coolant transport pipe for a vehicle according to the present invention will be described in detail.

[0017] A resin composition for a coolant transport pipe for a vehicle according to the present invention (which may be referred to as the resin composition hereinafter) contains the following (A) and (B), wherein, in 100 mass% of a polymer component, (A) accounts for 75 mass% or more and 99 mass% or less, and (B) accounts for 1 mass% or more and 25 mass% or less. (A) A propylene-α-olefin block copolymer (which may be referred to as block polypropylene hereinafter) having a melt flow index of 0.2 g / 10 min or more and 1.5 g / 10 min or less as measured at 230°C under a load of 2.16 kg. (B) A propylene homopolymer having a melt flow index of 2 g / 10 min or more and 50 g / 10 min or less when measured at 230°C under a load of 2.16 kg.

[0018] The resin composition described above can ensure low-temperature extrusion smoothness and physical properties by blending a high-viscosity block polypropylene and a low-viscosity homopolypropylene in a specific ratio. This makes it possible to achieve both the physical properties of the pipe and the smoothness of the pipe's inner surface. Low-temperature extrusion refers to performing extrusion at a temperature of 255°C or less, preferably within a temperature range of 190°C to 255°C.

[0019] The block polypropylene of (A) has a specific MFR (melt flow rate). If the MFR of the block polypropylene of (A) exceeds 1.5 g / 10 min, the physical properties cannot be guaranteed. The heat resistance also decreases. If the MFR of the block polypropylene of (A) is less than 0.2 g / 10 min, the flowability during extrusion cannot be guaranteed. By setting the MFR of the block polypropylene of (A) to 0.2 g / 10 min or more and 1.5 g / 10 min or less, the physical properties and flowability can be guaranteed. Furthermore, excellent heat resistance can be achieved. The MFR of the block polypropylene of (A) is more preferably 0.3 g / 10 min or more and 1.4 g / 10 min or less, more preferably 0.3 g / 10 min or more and 1.2 g / 10 min or less, and particularly preferably 0.3 g / 10 min or more and 1.0 g / 10 min or less.The MFR is measured according to JIS K 7210:1999 under conditions of 230°C and a load of 2.16 kg.

[0020] The block polypropylene of (A) is a propylene-α-olefin block copolymer. The propylene-α-olefin block copolymer is a block copolymer having at least one block formed by continuous propylene monomers and one block formed by continuous α-olefin monomers. The propylene-α-olefin block copolymer is not limited to the above and may be a plastic blend (blend) having an island structure in which a polypropylene component, such as a propylene homopolymer, forms the sea phase and a polyethylene component and / or an ethylene-based rubber component forms an island phase. The propylene-α-olefin block copolymer is a concept that includes such a plastic blend.

[0021] Examples of α-olefins include ethylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, etc. Of these, ethylene, 1-butene, and 1-hexene are preferred, and ethylene is particularly preferred. When the block polypropylene of (A) is an ethylene-propylene block copolymer, it is characterized by the effect of achieving both the physical properties of the pipe and the smoothness of the pipe's inner surface.

[0022] Examples of the polyethylene component include ethylene homopolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, and ethylene-based copolymers such as ethylene-α-olefin copolymers (ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-octene copolymer). Examples of the ethylene-based rubber component include ethylene-propylene-diene terpolymer (EPDM), ethylene-propylene copolymer (EPR), ethylene-butene copolymer (EBR), ethylene-octene copolymer (EOR), etc. The content ratio of the polyethylene component and / or the ethylene-based rubber component to the total plastic blend (mixture) is preferably 1 mass% to 49 mass%, and more preferably 2.5 mass% to 20 mass%.

[0023] The homopolypropylene of (B) has a specific MFR. If the MFR of the homopolypropylene of (B) exceeds 50 g / 10 min, the deterioration of physical properties becomes significant. If the MFR of the homopolypropylene of (B) is less than 2 g / 10 min, the effect of improving the smoothness of the pipe inner surface is poor. By setting the MFR of the homopolypropylene of (B) to 2 g / 10 min or more and 50 g / 10 min or less, it is possible to ensure the effect of improving the physical properties of the pipe and the smoothness of the pipe inner surface. The MFR of the homopolypropylene of (B) is preferably 5 g / 10 min or more and 50 g / 10 min or less, and more preferably 10 g / 10 min or more and 50 g / 10 min or less. When the MFR of the homopolypropylene of (B) is 10 g / 10 min or more and 50 g / 10 min or less, it is characterized by the effect of improving the smoothness in extrusion at low temperatures.The MFR is measured according to JIS K 7210:1999 under conditions of 230°C under a load of 2.16 kg.

[0024] It is preferable that there is a large difference in MFR between the block polypropylene of (A) and the homopolypropylene of (B). With a large difference in MFR between the block polypropylene of (A) and the homopolypropylene of (B), the homopolypropylene of (B) tends to appear on the pipe surface, which improves the smoothness of the pipe inner surface. From this point of view, the difference in MFR between the block polypropylene of (A) and the homopolypropylene of (B) is preferably 5 g / 10 min or more, more preferably 10 g / 10 min or more, and still more preferably 15 g / 10 min or more. On the other hand, the upper limit of the difference in MFR between the block polypropylene of (A) and the homopolypropylene of (B) is not specifically limited, but is preferably 50 g / 10 min or less, and more preferably 45 g / 10 min or less.

[0025] In 100 mass% of the polymer component, the block polypropylene of (A) accounts for 75 mass% or more and 99 mass% or less, and the homopolypropylene of (B) accounts for 1 mass% or more and 25 mass% or less. If the block polypropylene of (A) accounts for less than 75 mass%, the physical properties cannot be guaranteed. If the block polypropylene of (A) exceeds 99 mass%, the flowability during extrusion cannot be guaranteed. Furthermore, the smoothness of the pipe inner surface decreases. If the ratio between the block polypropylene of (A) and the homopolypropylene of (B) is within the above range, the physical properties and flowability during extrusion can be guaranteed, and the effect of improving the smoothness of the pipe inner surface can be ensured.Furthermore, from this point of view, the block polypropylene of (A) more preferably accounts for 85 mass% or more and 97 mass% or less in 100 mass% of the polymer component, and more preferably 90 mass% or more and 97 mass% or less. Furthermore, the homopolypropylene of (B) more preferably accounts for 3 mass% or more and 15 mass% or less in 100 mass% of the polymer component, and more preferably 3 mass% or more and 10 mass% or less. When the block polypropylene of (A) accounts for 90 mass% or more and 97 mass% or less and the homopolypropylene of (B) accounts for 3 mass% or more and 10 mass% or less in 100 mass% of the polymer component, both the effect of improving smoothness upon extrusion at low temperatures and the high level of physical properties can be achieved.

[0026] The resin composition may contain other resin components in addition to (A) and (B) within a range that does not impair the effect of the present invention. The other resin components may include modified resins that make these components compatible. Examples of such modified resins include acid-modified or carboxy-modified polypropylene. The content of the modified resins is not specifically limited, but is from 0.5 parts by mass to 10 parts by mass, and preferably from 0.5 parts by mass to 5 parts by mass, based on 100 parts by mass of the block polypropylene of (A).

[0027] Examples of the acid or its derivatives in the acid-modified material include unsaturated carboxylic acids and their derivatives. Examples of unsaturated carboxylic acids include maleic acid, fumaric acid, acrylic acid, methacrylic acid, etc. Examples of unsaturated carboxylic acid derivatives include acid anhydride of unsaturated carboxylic acid, ester compound, amide compound, imide compound, metal salt, etc.

[0028] The resin composition may contain other components in addition to (A) and (B) within a range that does not impair the effect of the present invention. Examples of the other components include filler, weather stabilizer, lubricant, pigment, dye, antistatic agent, plasticizer, reinforcing agent, antioxidant, etc.

[0029] Examples of fillers include inorganic fillers such as talc, silica, mica, kaolin, calcium carbonate, potassium titanate, apatite, mica, etc. These can be used alone or in combination with two or more. Among them, talc is preferred from the perspective of extrusion processability, reinforcement properties, etc.

[0030] The content of filler is not specifically limited, but from the viewpoint of strength, it is 1 mass part to 100 mass parts based on 100 mass parts of the block polypropylene of (A), and preferably 10 mass parts to 70 mass parts.

[0031] Examples of the antioxidant include phenolic antioxidants, amine-based antioxidants, imidazole-based antioxidants, phosphoric acid-based antioxidants, etc. The antioxidant may be composed of only one of these or two or more of them. Among them, phenolic antioxidants are preferred from the viewpoint of excellent heat resistance. Furthermore, hindered phenolic antioxidants are particularly preferred from the viewpoint of heat resistance.

[0032] The content of the antioxidant is not specifically limited, but is, based on 100 parts by mass of the block polypropylene of (A), 0.5 parts by mass to 1.0 parts by mass, and preferably 0.1 parts by mass to 1.0 parts by mass.

[0033] According to the resin composition described above, by blending high-viscosity block polypropylene and low-viscosity homopropylene in a specific ratio, both the low-temperature extrusion smoothness and the physical properties can be ensured. This makes it possible to achieve both the physical properties of the pipe and the smoothness of the pipe's inner surface.

[0034] A coolant transport pipe for a vehicle according to the present invention (which may be referred to as the resin pipe hereinafter) can be obtained from the resin composition. The resin pipe is suitably implemented as a resin pipe 10 with a single-layer structure, as shown in, for example, Fig. 1. Furthermore, if necessary, the resin pipe can be manufactured as a resin pipe with a multi-layer structure by additionally laminating additional resin layers or reinforcing fiber layers.

[0035] From the point of view of application, the resin pipe preferably has an inner diameter in a range of 2.5 mm to 30 mm, in particular 4 mm to 25 mm and a thickness in a range of 0.5 mm to 5.0 mm, in particular 0.75 mm to 4.0 mm.

[0036] The resin pipe is used, for example, for coolant piping in a motor vehicle and in particular, the resin pipe is suitable for radiator hoses, heater hoses, air conditioning hoses, etc. or for cooling pipes of battery packs in an electric vehicle or a fuel cell vehicle.

[0037] The resin tube can be produced by melt extrusion, in which the resin composition is formed into a tubular shape. The resin composition can be obtained by mixing and kneading (A) and (B) and optionally blended components.

[0038] The kneading process of the resin composition can be carried out, for example, using a twin-screw kneading extruder. The kneading temperature is preferably 190°C to 230°C. The kneading time is preferably 0.01 min to 10 min.

[0039] The extrusion process of the resin composition can be carried out using, for example, a twin-screw kneading extruder. From the perspective of improving the smoothness of the inner surface of the pipe during low-temperature extrusion, the extrusion temperature is preferably 190°C to 255°C.

[0040] In the resin pipe, it is preferred that the homopolypropylene of (B) appears on the pipe surface, resulting in more homopolypropylene of (B) being present in the outer part in the radial direction of the pipe. By using the resin composition, the homopolypropylene of (B) can be unevenly distributed in the resin pipe as described above, and such a configuration is characterized by the effect of improving the smoothness of the inner surface of the pipe. The outer part in the radial direction of the pipe refers to the portion located at or near the surface in the radial direction of the pipe, and represents the outer peripheral surface or the inner peripheral surface of the pipe, or a portion close to the outer peripheral surface or the inner peripheral surface of the pipe. The inner part in the radial direction of the pipe refers to the portion located inward in the radial direction relative to the outer part, and is, for example,a section that includes the central part in the radial direction, etc.

[0041] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments in any way, and numerous modifications are possible within the scope which do not deviate from the spirit of the present invention. Examples

[0042] The present invention will be described in detail below with the help of examples and comparative examples. (Examples 1 to 6, comparative examples 1 to 3)

[0043] The components were mixed in the mixing ratios (mass fractions) shown in the table and kneaded for 5 minutes at 200°C using a twin-screw kneading extruder ("TEM-18SS", manufactured by Toshiba Machine) to obtain a kneaded material. Next, the kneaded material was pelletized, and the pellets were melt-extruded into a tube shape at 250°C using a melt-extrusion press ("GT-40", manufactured by Research Laboratory of Plastics Technology Co., Ltd.) equipped with a cylindrical die to obtain a resin tube with an inner diameter of 18 mm and an outer diameter of 20 mm.

[0044] The materials used were the following: (A) Propylene-α-olefin block copolymer • Block PP <1> : “E-701G” manufactured by Prime Polymer, MFR 0.5 g / 10 min • Block PP <2> : “E-702MG” manufactured by Prime Polymer, MFR 1.4 g / 10 min (B) Propylene homopolymer • Homo PP <1> : “E200GP” manufactured by Prime Polymer, MFR 2.0 g / 10 min • Homo PP <2> : “J106MG” manufactured by Prime Polymer, MFR 16 g / 10 min • Homo PP <3> : “J108M”, MFR 45 g / 10 min (B') Propylene homopolymer manufactured by Prime Polymer • Homo PP <4> : “E200GPL” manufactured by Prime Polymer, MFR 1.4 g / 10 min • Homo PP <5> : "C14EP348U" manufactured by Lyondellbasell, MFR 70 g / 10 min

[0045] For the obtained resin pipes, an evaluation of each property was performed according to the following criteria. The results are shown in Table 1 below. <Glätte (Extrusion bei niedrigen Temperaturen)>

[0046] The resulting resin tube was cut in half, and measurements were taken with a caliper at three locations: the central portion and near the left and right cross sections. Compared to the target thickness (1.0 mm), those that deviated by more than 0.05 mm at any of the three locations were classified as "X," those where all three locations were within 0.05 mm and any one location was exactly 0.05 mm were classified as "O," and those where all three locations deviated by less than 0.05 mm were classified as "O." <Physikalische Eigenschaften>

[0047] After heat-treating the resin tube at 160°C for 1 hour, the resin tube was cut in half and punched into strip samples with a width of 10 mm and a length of 15 cm. The elongation at break [Eb] of the obtained strip samples was measured using a tensile testing machine (AGS-X, manufactured by Shimadzu Corporation) according to JIS K 6251. Those with an elongation at break of 350% or more were classified as "⊙", those with an elongation at break of 300% or more were classified as "◯", and those with an elongation at break of less than 300% were classified as "×". [Table 1] MFR Example Comparison example g / 10 min 1 2 3 4 5 6 1 2 3 (A) BlockPP <1> 0,5 95 95 95 80 98 - 95 95 70 BlockPP <2> 1,4 - - - - - 95 - - - (B) HomoPP <1> 2,0 5 - - - - - - - - HomoPP <2> 16 - 5 - 20 2 5 - - 30 HomoPP <3> 45 - - 5 - - - - - - (B') HomoPP <4> 1,4 - - - - - - 5 - - HomoPP <5> 70 - - - - - - - 5 - Smoothness (extrusion at low temperatures) ◯ ◯ ◯ ◯ ◯ ◯ × ◯ ◯ Middle part (mm) 1,01 0,99 0,99 1,01 1,01 0,99 1,02 1,00 1,02 Right end part (mm) 1,05 1,03 1,02 1,01 1,04 1,02 1,07 1,02 1,01 Left end part (mm) 0,97 0,99 0,98 0,98 0,95 0,97 0,96 0,97 1,00 Physical properties ⊙ ⊙ ⊙ ◯ ⊙ ⊙ ⊙ × × Elongation at break[Eb] (%) 410 450 380 310 430 400 430 150 170

[0048] In Comparative Example 1, since a propylene homopolymer with an MFR of 1.4 g / 10 min was used, the smoothness of the pipe's inner surface deteriorated during extrusion at low temperatures. In Comparative Example 2, since a propylene homopolymer with an MFR of 70 g / 10 min was used, the elongation at break was low and the physical properties deteriorated. In Comparative Example 3, although a propylene homopolymer with an MFR of 16 g / 10 min was used, an excessive amount was blended, so the elongation at break was low and the physical properties deteriorated.

[0049] In contrast, the examples correspond to the physical properties with sufficient elongation at break. Furthermore, the examples are characterized by the smoothness of the inner pipe surface, even during extrusion at low temperatures. From the above, it is confirmed that by using a resin composition comprising (A) a propylene-α-olefin block copolymer having a melt flow index of 0.2 g / 10 min or more and 1.5 g / 10 min or less as measured at 230°C under a load of 2.16 kg, and (B) a propylene homopolymer having a melt flow index of 2 g / 10 min or more and 50 g / 10 min or less as measured at 230°C under a load of 2.16 kg, wherein in 100 mass% of the polymer component, (A) accounts for 75 mass% or more and 99 mass% or less, and (B) accounts for 1 mass% or more and 25 mass% or less, the smoothness upon extrusion at low temperatures and the physical properties can be ensured.

[0050] From the comparison of Examples 1 to 3, it is clear that the smoothness of the pipe inner surface further improves when the difference in MFR between (A) and (B) is 5 g / 10 min or more. Furthermore, it is clear from Examples 1 to 3 that the effect of improving the smoothness in low-temperature extrusion is even better when the MFR of (B) is 10 g / 10 min or more and 50 g / 10 min or less. Furthermore, it is clear from Examples 2, 4, and 5 that both the effect of improving the smoothness in low-temperature extrusion and the physical properties can be achieved at a high level when (A) accounts for 90 mass% or more and 97 mass% or less and (B) accounts for 3 mass% or more and 10 mass% or less in 100 mass% of the polymer component.

[0051] The embodiments and examples of the present invention have been described above, but the present invention is not limited to the above embodiments and examples, and various changes are possible within the scope without departing from the spirit of the present invention. List of reference symbols 10 resin pipe QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2012-091730

[0002]

Claims

[1] A resin composition for a coolant transport pipe for a vehicle comprising the following (A) and (B), wherein in 100 mass% of a polymer component, (A) accounts for 75 mass% or more and 99 mass% or less, and (B) accounts for 1 mass% or more and 25 mass% or less, (A) a propylene-α-olefin block polymer having a melt flow index of 0.2 g / 10 min or more and 1.5 g / 10 min or less, measured at 230°C under a load of 2.16 kg, (B) a propylene homopolymer having a melt flow index of 2 g / 10 min or more and 50 g / 10 min or less when measured at 230°C under a load of 2.16 kg. [2] The resin composition for the coolant transport pipe for a vehicle according to claim 1, wherein (A) and (B) have a difference in melt flow index of 5 g / 10 min or more when measured at 230°C under a load of 2.16 kg. [3] The resin composition for the coolant transport pipe for a vehicle according to claim 1 or 2, wherein the melt flow index of (B) measured at 230°C under a load of 2.16 kg is 10 g / 10 min or more and 50 g / 10 min or less. [4] The resin composition for the coolant transport pipe for a vehicle according to any one of claims 1 to 3, wherein, in 100 mass% of the polymer component, (A) accounts for 90 mass% or more and 97 mass% or less, and (B) accounts for 3 mass% or more and 10 mass% or less. [5] The resin composition for the coolant transport pipe for a vehicle according to any one of claims 1 to 4, wherein (A) is an ethylene-propylene block copolymer. [6] A coolant transport pipe for a vehicle comprising the resin composition for the coolant transport pipe for a vehicle according to any one of claims 1 to 5. [7] A coolant transport pipe for a vehicle according to claim 6, wherein (B) occurs more in an outer part than in an inner part in a radial direction of the coolant transport pipe for a vehicle.

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