Low-dielectric polypropylene resin composition for automotive communication cables

Abstract

To provide a polypropylene resin composition exhibiting low dielectric property, which is used as an internal coating material for an automobile communication cable.SOLUTION: A polypropylene resin composition contains a polypropylene-based resin containing a first polypropylene-based resin and a second polypropylene-based resin, wherein when the first polypropylene-based resin is measured at a load of 2.16 kg and 230°C, it has a melt index of 2.3 to 3.3 g / 10 min and a content of a xylene soluble part of 18 to 22 wt.%, when the second polypropylene-based resin is measured at a load of 2.16 kg and 230°C, it has a melt index of 1.5 to 2.0 g / 10 min and a content of a xylene soluble part of 13 to 17 wt.%, and a content ratio based on the weight of the second polypropylene-based resin to the first polypropylene-based resin is within a range of 9:1 to 7:3.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a low-dielectric polypropylene resin composition for automotive communication cables and molded products manufactured therefrom. Specifically, the present invention relates to a low-dielectric polypropylene resin composition used as an inner coating material for automotive communication cables and an inner coating material for automotive communication cables manufactured therefrom.

Background Art

[0002] Polypropylene resin, which is a kind of general-purpose resin, is excellent not only in economy but also in mechanical properties, moldability, chemical resistance, etc., and is widely used as a material for films, pipes, interior and exterior parts of automobiles, parts of electric and household appliances, building and industrial materials, etc.

[0003] In particular, since polypropylene resin has excellent insulation properties, attempts have been made to use it as an insulating material for power cables.

[0004] For example, Patent Document 1 discloses a polypropylene resin composition containing a propylene homopolymer or a random copolymer of propylene and one or more propylene external α-olefins, and having the content of metallic catalyst residues adjusted to a certain level or less.

[0005] Also, Patent Document 2 discloses a technique for improving insulation resistance by surface-treating inorganic nanoparticles by a sol-gel reaction of a hydroxy acid and a silane and blending this with a polypropylene resin.

[0006] However, the development of a polypropylene resin composition suitable for use as an inner coating material for automotive communication cables is required.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

[0008] The object of the present invention is to provide a low-dielectric polypropylene resin composition and a molded article manufactured thereby, specifically an internal coating material for automotive communication cables, that is suitable for use as an internal coating material for automotive communication cables. [Means for solving the problem]

[0009] As one embodiment of the present invention to achieve the above objective, a polypropylene resin composition is provided, characterized in that the polypropylene resin (A) comprises (A1) a first polypropylene resin and (A2) a second polypropylene resin, the first polypropylene resin (A1) has a melting index of 2.3 to 3.3 g / 10 min and a xylene-soluble portion content of 18 to 22% by weight when measured at 230°C with a load of 2.16 kg, the second polypropylene resin (A2) has a melting index of 1.5 to 2.0 g / 10 min and a xylene-soluble portion content of 13 to 17% by weight when measured at 230°C with a load of 2.16 kg, and the weight-based content ratio of the first polypropylene resin to the second polypropylene resin is in the range of 9:1 to 7:3.

[0010] In a specific example of the present invention, the first polypropylene resin (A1) and the second polypropylene resin (A2) may each be an ethylene-propylene block copolymer.

[0011] In a specific example of the present invention, the polypropylene resin composition may further contain, based on the total weight of components (A) to (D), (B) 0 to 1.0% by weight of an antioxidant, (C) 0 to 1.0% by weight of a long-term heat-resistant stabilizer, and (D) 0 to 1.0% by weight of a neutralizing agent.

[0012] In a specific example of the present invention, the antioxidant (B) may include at least one selected from the group consisting of pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, 2',3-bis[{3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyl}]propionohydrazide, and tris(2,4-di-t-butylphenyl)phosphite.

[0013] In a specific example of the present invention, the long-term heat-resistant stabilizer (C) may include at least one selected from the group consisting of distearyl thiodipropionate, dilauryl thiodipropionate, dimyristyl thiodipropionate, ditridecyl thiodipropionate, dioctadecyl 3,3-thiodipropionate, 2,2'-thiobis(4-methyl-6-tert-butylphenol), tetrakis(3-laurylthiopropionyloxymethyl)methane, pentaerythritol tetrakis(3-dodecylthiopropionate), lauryl 3,3'-thiodipropionate, stearyl 3,3'-thiodipropionate, distearyl disulfide, and 3,3'-thiobisdidodecyl ester propionic acid.

[0014] In a specific example of the present invention, the neutralizing agent (D) may include at least one selected from the group consisting of calcium stearate and hydrotalcite.

[0015] In a specific example of the present invention, the antioxidant (B) may be pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], the long-term heat-resistant stabilizer (C) may be distearyl thiodipropionate, and the neutralizing agent (D) may be calcium stearate.

[0016] In a specific example of the present invention, the polypropylene resin composition may further contain at least one additive selected from the group consisting of a slip agent, an antiblocking agent, a filler, a weather stabilizer, an antistatic agent, an activator, a nucleating agent, and a dye.

[0017] According to another embodiment of the present invention, there is provided a polypropylene resin molded article manufactured by molding the polypropylene resin composition.

[0018] In a specific example of the present invention, the polypropylene resin molded article may satisfy the conditions of a Shore D hardness of 58 to 65, a capacitance of 104 ± 5 nF, a characteristic impedance of 50 ± 2 Ω / km, and the following attenuation amounts: 0.76 dB / m or less at 900 MHz; 1.04 dB / m or less at 1500 MHz; 1.08 dB / m or less at 1600 MHz; 1.20 dB / m or less at 1900 MHz; 1.23 dB / m or less at 2000 MHz; 1.40 dB / m or less at 2500 MHz; 1.59 dB / m or less at 3000 MHz.

[0019] In a specific example of the present invention, the polypropylene resin molded article may be an inner coating material for an automotive communication cable.

Advantages of the Invention

[0020] The polypropylene resin composition according to an embodiment of the present invention exhibits low dielectric properties and can be effectively used as an inner coating material for automotive communication cables.

Modes for Carrying Out the Invention

[0021] Hereinafter, the present invention will be described in more detail. The polypropylene resin composition according to one embodiment of the present invention contains (A) a polypropylene-based resin, and the polypropylene-based resin (A) contains (A1) a first polypropylene-based resin and (A2) a second polypropylene-based resin. The first polypropylene-based resin (A1) has a melt index of 2.3 to 3.3 g / 10 min and a xylene-soluble portion content of 18 to 22% by weight when measured at 230°C under a load of 2.16 kg. The second polypropylene-based resin (A2) has a melt index of 1.5 to 2.0 g / 10 min and a xylene-soluble portion content of 13 to 17% by weight when measured at 230°C under a load of 2.16 kg. The content ratio of the first polypropylene-based resin to the second polypropylene-based resin on a weight basis is in the range of 9:1 to 7:3.

[0022] (A) Polypropylene-based resin The polypropylene resin composition according to an embodiment of the present invention contains a polypropylene-based resin (A). In the polypropylene resin composition according to an embodiment of the present invention, the polypropylene-based resin (A) contains (A1) a first polypropylene-based resin and (A2) a second polypropylene-based resin.

[0023] In a specific example of the present invention, the first polypropylene-based resin (A1) and the second polypropylene-based resin (A2) can each be an ethylene-propylene block copolymer. The ethylene-propylene block copolymer can be obtained by stepwise polymerization in a reactor of a matrix component of a propylene homopolymer or a propylene-ethylene or propylene-α-olefin random copolymer and an ethylene-propylene rubber copolymer component.

[0024] There are no particular limitations on the method for producing ethylene-propylene block copolymers, and methods for producing ethylene-propylene block copolymers known in the art to which the present invention belongs can be used as is or with appropriate modifications. For example, ethylene-propylene block copolymers can be produced by polymerization methods known to the ordinary art in commercially available processes such as LyondellBasell's Spherizone process, Mitsui's Hypol process, or Grace's Unipol process.

[0025] The first polypropylene resin (A1) has a melting index of 2.3 to 3.3 g / 10 min and a xylene-soluble content of 18 to 22% by weight when measured at 230°C with a 2.16 kg load in accordance with ASTM D1238. When the melting index and xylene-soluble content of the first polypropylene resin (A1) satisfy the above ranges, it can exhibit excellent moldability, excellent roundness, hardness (Shore D), and low dielectric properties (capacitance).

[0026] The second polypropylene resin (A2) has a melting index of 1.5 to 2.0 g / 10 min and a xylene-soluble content of 13 to 17% by weight when measured at 230°C under a 2.16 kg load in accordance with ASTM D1238. When the melting index and xylene-soluble content of the second polypropylene resin (A2) satisfy the above ranges, it can exhibit excellent moldability, excellent roundness, hardness (Shore D), and low dielectric properties (standard decay).

[0027] The xylene-soluble portion content of the first polypropylene resin (A1) and the second polypropylene resin (A2) can be measured in accordance with ASTM D5492. Specifically, the polypropylene resin is dissolved in xylene at a concentration of 1% by weight at 140°C for 1 hour, and then the weight of the extracted material is measured after 2 hours at room temperature (23°C). The obtained weight is expressed as a percentage of the weight of the polypropylene resin.

[0028] The weight-based content ratio of the first polypropylene resin (A1) to the second polypropylene resin (A2) in the polypropylene resin (A) is in the range of 9:1 to 7:3. Preferably, the weight-based content ratio of the first polypropylene resin (A1) to the second polypropylene resin (A2) in the polypropylene resin (A) may be in the range of 8.5:1.5 to 7.5:2.5. If the weight-based content ratio of the first polypropylene resin (A1) to the second polypropylene resin (A2) falls outside the above range, the low dielectric effect expected in the present invention may not be obtained.

[0029] A polypropylene resin composition according to one embodiment of the present invention may substantially contain only polypropylene resin (A), and may further contain components (B) to (D) as described later, if necessary. Therefore, a polypropylene resin composition according to one embodiment of the present invention may contain polypropylene resin (A) in an amount of 97.5 to 100% by weight, based on the total weight of components (A) to (D). Preferably, the content of polypropylene resin (A) in the polypropylene resin composition may be 98 to 99.5% by weight. If the content of polypropylene resin (A) in the polypropylene resin composition is less than 97.5% by weight, the low dielectric effect expected in the present invention may decrease, or the effect of adding components (B) to (D) may not increase further, making it uneconomical.

[0030] In a specific example of the present invention, the polypropylene resin composition may further contain, based on the total weight of components (A) to (D), (B) 0 to 1.0% by weight of an antioxidant, (C) 0 to 1.0% by weight of a long-term heat-resistant stabilizer, and (D) 0 to 1.0% by weight of a neutralizing agent.

[0031] (B) Antioxidants The polypropylene resin composition according to an embodiment of the present invention may contain an antioxidant (B).

[0032] In specific examples of the present invention, antioxidant (B) may include at least one selected from the group consisting of pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, 2',3-bis[{3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyl}]propionohydrazide, and tris(2,4-di-t-butylphenyl)phosphite. Preferably, antioxidant (B) may include pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate].

[0033] A polypropylene resin composition according to one embodiment of the present invention may contain antioxidant (B) in an amount of 0 to 1.0% by weight, based on the total weight of components (A) to (D). Including antioxidant (B) can improve the antioxidant effect of the resin composition, but if the content of antioxidant (B) exceeds 1.0% by weight, the antioxidant effect will not increase further, which may make it uneconomical.

[0034] (C) Long-term heat-resistant stabilizer A polypropylene resin composition according to an embodiment of the present invention may contain a long-term heat-resistant stabilizer (C).

[0035] In specific examples of the present invention, the long-term heat-resistant stabilizer (C) is distearyl thiodipropionate, dilauryl thiodipropionate, dimyristyl thiodipropionate, ditridecyl thiodipropionate, or dioctadecyl 3,3-thiodipropionate. 3,3-thiodipropionate), 2,2'-thiobis(4-methyl-6-tert-butylphenol), tetrakis(3-laurylthiopropionyloxy-methyl)methane, pentaerythritol tetrakis(3-dodecylthiopropionate), lauryl 3,3'-thiodipropionate, stearyl 3,3'-thiodipropionate, distearyl disulfide, and 3,3'-thiobisdidodecyl propionic acid It may contain at least one selected from the group consisting of 3,3'-thiobisdidodecyl ester. Preferably, the long-term heat-resistant stabilizer (C) may contain distearyl thiodipropionate.

[0036] A polypropylene resin composition according to one embodiment of the present invention may contain a long-term heat stabilizer (C) in an amount of 0 to 1.0% by weight, based on the total weight of components (A) to (D). Including a long-term heat stabilizer (C) ensures the long-term heat stability of the resin composition, allowing it to maintain desirable physical properties even after prolonged use. However, if the content of the long-term heat stabilizer (C) exceeds 1.0% by weight, the effect of long-term heat stability does not increase further, which may make it uneconomical.

[0037] (D) Neutralizing agent The polypropylene resin composition according to an embodiment of the present invention may contain a neutralizing agent (D).

[0038] In specific examples of the present invention, the neutralizing agent (D) may include at least one selected from the group consisting of calcium stearate and hydrotalcite. Preferably, the neutralizing agent (D) may include calcium stearate.

[0039] A polypropylene resin composition according to one embodiment of the present invention may contain a neutralizing agent (D) in an amount of 0 to 1.0% by weight, based on the total weight of components (A) to (D). Including a neutralizing agent (D) effectively removes residual components of the catalyst used in the production of the polypropylene resin (A). However, if the content of the neutralizing agent (D) exceeds 1.0% by weight, the effect of removing residual catalyst components does not increase further, which may make it uneconomical.

[0040] (E) Additives A polypropylene resin composition according to an embodiment of the present invention may further contain conventional additives, without departing from the scope of the present invention. For example, a polypropylene resin composition according to an embodiment of the present invention may further contain at least one additive selected from the group consisting of slip agents, antiblocking agents, fillers, weather stabilizers, antistatic agents, activators, nucleating agents, and dyes.

[0041] There are no particular limitations on the method for producing a polypropylene resin composition according to the embodiment of the present invention. Methods for producing polypropylene resin compositions known in the art to which the present invention belongs can be used as is or modified as appropriate. The aforementioned resin components and compounds can be freely selected and mixed according to a desired procedure without any restrictions on special procedures.

[0042] To give a specific example, the required amounts of each resin and compound mentioned above can be mixed for 1 to 2 hours in a kneader such as a Henschel mixer, kneader, roll, or Banbury mixer, and then melted and kneaded at a temperature of 180 to 210°C using a single-screw / twin-screw extruder to produce a pelletized polypropylene resin composition.

[0043] Another embodiment of the present invention provides a polypropylene resin molded article manufactured by molding the polypropylene resin composition of the present invention.

[0044] There are no particular limitations on the method for producing molded articles using the polypropylene resin composition according to the embodiment of the present invention, and methods known in the art to which the present invention belongs can be used. For example, a polypropylene resin molded article can be produced by molding the polypropylene resin composition according to the embodiment of the present invention using conventional methods such as injection molding, extrusion molding, or casting molding.

[0045] In a specific example of the present invention, the polypropylene resin molded article can satisfy the following conditions: Shore D hardness of 58-65, capacitance of 104±5nF, characteristic impedance of 50±2Ω / km, and the following attenuation: Less than 0.76 dB / m at 900 MHz; Less than 1.04 dB / m at 1500 MHz; Less than 1.08 dB / m at 1600 MHz; Less than 1.20 dB / m at 1900 MHz; Less than 1.23 dB / m at 2000 MHz; Less than 1.40 dB / m at 2500 MHz; Less than 1.59 dB / m at 3000 MHz.

[0046] In a specific example of the present invention, the polypropylene resin molded product may be an internal covering material for an automotive communication cable.

[0047] (Examples) The present invention will be described more specifically below with reference to examples and comparative examples. However, the following examples are for illustrative purposes only, and the scope of the present invention is not limited thereto.

[0048] The raw materials used in the examples and comparative examples are as follows: A1: Ethylene-propylene block copolymer resin (Hanwha Total Energy Co., Ltd., BJ200; MI 3g / 10 min, xylene-soluble content 18-22% by weight) A2: Ethylene-propylene block copolymer resin (Hanwha Total Energy Co., Ltd., BJ100; MI 2g / 10 min, xylene-soluble portion content 13-17% by weight) B1: Antioxidant (Pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]) C1: Long-term heat-resistant stabilizer (distearyl thiodipropionate) D1: Neutralizing agent (calcium stearate) E1: Antistatic agent (Sanyo Chemical Industries, Ltd., Pelestat® 230)

[0049] (Manufacturing example) The resins and compounds of the types and quantities (in parts by weight) shown in Table 1 below were melt-blended at a temperature of approximately 180-210°C using a twin-screw extruder and then pelletized. The manufactured pellets were co-extruded with electric wires using a communication wire extruder to produce communication wires, and the manufactured electric wires were then subjected to metal shielding and outer coating to produce automotive communication wires.

[0050] [Table 1]

[0051] (Example test) The automotive communication wires obtained in each example and comparative example were tested using the following method. The results are shown in Table 2 below.

[0052] (1)Hardness A 6mm thick test specimen was injected, and after 48 hours, its hardness was measured using a Shore D hardness tester.

[0053] (2) Capacitance (KS C 3004) Capacitance refers to the degree to which electric charge can be stored between electrodes. In the case of shielded wires, charge accumulates between the wire cores or between the wire cores and the shielding layer, which generates noise during signal transmission. This is called capacitance. A 50m sample of the wire to be measured was left in air at a temperature of 20±5℃ and a humidity of 65±5%, and the capacitance was measured between points A and B using an LCR meter as shown in the figure below. The measurement frequency was set to 1000Hz. JPEG0007881685000002.jpg39150

[0054] (3) Characteristic impedance (KS C 3610) The ratio of the AC voltage applied to an AC circuit to the AC current flowing through that circuit is called impedance (Ω). Samples were taken from wires 10m or longer in length, measured using a network analyzer, and then converted to a value per meter of cable. The measurement frequency range was the same as that used for measuring attenuation.

[0055] (4) Standard damping amount (KS C 3610) The ratio of the output power to the input power of a power line is called the standard attenuation (dB), and the signal loss of the input power is called the standard attenuation. It is measured using a standard attenuation meter, and the measurement range was the same as that of impedance.

[0056] (5) Roundness of the electric wire The roundness of the manufactured electric wires was measured using a 3D measuring machine.

[0057] [Table 2]

[0058] As can be seen from Tables 1 and 2 above, the automotive communication wires manufactured using the polypropylene resin compositions of the examples within the scope of the present invention exhibited excellent hardness, capacitance, characteristic impedance, attenuation, and wire roundness.

[0059] On the other hand, in Comparative Examples 1 to 4, which contained only one type of ethylene-propylene block copolymer resin, at least one of the following characteristics—hardness, capacitance, characteristic impedance, attenuation, and wire roundness—was unsatisfactory. In particular, in Comparative Examples 3 and 4, despite containing an antistatic agent, it was confirmed that the standard attenuation did not meet the required specifications.

[0060] Therefore, polypropylene resin compositions according to embodiments within the scope of the present invention can be effectively used as internal coating materials for automotive communication cables.

Claims

1. (A) Contains polypropylene resin, The polypropylene resin (A) comprises (A1) a first polypropylene resin and (A2) a second polypropylene resin. The first polypropylene resin (A1) has a melting index of 2.3 to 3.3 g / 10 min and a xylene-soluble portion content of 18 to 22% by weight when measured at 230°C under a load of 2.16 kg. The second polypropylene resin (A2) has a melting index of 1.5 to 2.0 g / 10 min and a xylene-soluble portion content of 13 to 17% by weight when measured at 230°C under a load of 2.16 kg. The weight-based content ratio of the first polypropylene resin to the second polypropylene resin is in the range of 9:1 to 7:

3. A polypropylene resin composition characterized in that the first polypropylene resin (A1) and the second polypropylene resin (A2) are each ethylene-propylene block copolymers.

2. The polypropylene resin composition according to claim 1, further comprising (B) 0 to 1.0% by weight of an antioxidant, (C) 0 to 1.0% by weight of a long-term heat-resistant stabilizer, and (D) 0 to 1.0% by weight of a neutralizing agent, based on the total weight of components (A) to (D).

3. The polypropylene resin composition according to claim 2, wherein the antioxidant (B) comprises at least one selected from the group consisting of pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, 2',3-bis[{3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyl}]propionohydrazide, and tris(2,4-di-t-butylphenyl)phosphite.

4. The polypropylene resin composition according to claim 2, wherein the long-term heat-resistant stabilizer (C) comprises at least one selected from the group consisting of distearyl thiodipropionate, dilauryl thiodipropionate, dimyristyl thiodipropionate, ditridecyl thiodipropionate, dioctadecyl 3,3-thiodipropionate, 2,2'-thiobis(4-methyl-6-tert-butylphenol), tetrakis(3-laurylthiopropionyloxymethyl)methane, pentaerythritol tetrakis(3-dodecylthiopropionate), lauryl 3,3'-thiodipropionate, stearyl 3,3'-thiodipropionate, distearyl disulfide, and 3,3'-thiobisdidodecyl ester propionic acid.

5. The polypropylene resin composition according to claim 2, wherein the neutralizing agent (D) comprises at least one selected from the group consisting of calcium stearate and hydrotalcite.

6. The polypropylene resin composition according to claim 2, wherein the antioxidant (B) is pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], the long-term heat-resistant stabilizer (C) is distearyl thiodipropionate, and the neutralizing agent (D) is calcium stearate.

7. The polypropylene resin composition according to claim 1, further comprising at least one additive selected from the group consisting of slip agents, antiblocking agents, fillers, weather stabilizers, antistatic agents, activators, nucleating agents, and dyes.

8. A polypropylene resin molded article produced by molding a polypropylene resin composition according to any one of claims 1 to 7.

9. A polypropylene resin molded article according to claim 8, satisfying the following conditions: Shore D hardness of 58 to 65, capacitance of 104 ± 5 ​​nF, characteristic impedance of 50 ± 2 Ω / km, and the following attenuation: Less than 0.76 dB / m at 900 MHz; Less than 1.04 dB / m at 1500 MHz; Less than 1.08 dB / m at 1600 MHz; Less than 1.20 dB / m at 1900 MHz; Less than 1.23 dB / m at 2000 MHz; Less than 1.40 dB / m at 2500 MHz; and Less than 1.59 dB / m at 3000 MHz.

10. A polypropylene resin molded article according to claim 8, which is an internal covering material for automotive communication cables.

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