Low dielectric polypropylene resin composition for automobile communication cable

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 a molded article produced therefrom. More 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 produced therefrom. [Background technology]

[0002] Polypropylene resin, a type of general-purpose resin, is not only economical but also has excellent mechanical properties, moldability, and chemical resistance, and is used in a variety of applications, including as a material for films, pipes, interior and exterior automotive parts, electrical and home appliance parts, and construction and industrial materials.

[0003] In particular, polypropylene resin has excellent insulating properties, and 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 α-olefins other than propylene, in which the content of metallic catalyst residues is adjusted to a certain level or less.

[0005] Furthermore, Patent Document 2 discloses a technique in which inorganic nanoparticles are surface-treated by a sol-gel reaction between a hydroxy acid and a silane, and then blended with a polypropylene resin to improve insulation resistance.

[0006] However, there is a need for the development of a polypropylene resin composition suitable for use as an inner coating material for automobile communication cables. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Korean Patent Publication No. 10-2018-0076413 [Patent Document 2] Korean Patent Publication No. 10-2021-0054135 Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a polypropylene resin composition having low dielectric properties suitable for use as an inner coating material for automobile communication cables, and a molded article produced therefrom, specifically an inner coating material for automobile communication cables. [Means for solving the problem]

[0009] In one embodiment of the present invention to achieve the above object, there is provided a polypropylene resin composition comprising (A) a polypropylene resin, wherein the polypropylene resin (A) comprises (A1) a first polypropylene resin and (A2) a second polypropylene resin, wherein the first polypropylene resin (A1) has a melt index of 2.3 to 3.3 g / 10 min and a xylene solubles content of 18 to 22 wt % when measured under a 2.16 kg load at 230°C, and the second polypropylene resin (A2) has a melt index of 1.5 to 2.0 g / 10 min and a xylene solubles content of 13 to 17 wt % when measured under a 2.16 kg load at 230°C, and the weight ratio of the first polypropylene resin to the second polypropylene resin is in the range of 9:1 to 7:3.

[0010] In an embodiment 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 an embodiment of the present invention, the polypropylene resin composition may further contain, based on the total weight of components (A) to (D), 0 to 1.0 wt % of (B) an antioxidant, 0 to 1.0 wt % of (C) a long-term heat stabilizer, and 0 to 1.0 wt % of (D) a neutralizing agent.

[0012] In an embodiment of the present invention, the antioxidant (B) may comprise 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 an embodiment of the present invention, the long-term heat stabilizer (C) may comprise 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-laurylthiopropionyloxy-methyl)methane, pentaerythritol tetrakis(3-dodecylthiopropionate), lauryl 3,3'-thiodipropionate, stearyl 3,3'-thiodipropionate, distearyl disulfide, and propionic acid 3,3'-thiobisdidodecyl ester.

[0014] In an embodiment of the present invention, the neutralizing agent (D) may comprise at least one selected from the group consisting of calcium stearate and hydrotalcite.

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

[0016] In an embodiment of the present invention, the polypropylene resin composition may further comprise at least one additive selected from the group consisting of slip agents, antiblocking agents, fillers, weather stabilizers, antistatic agents, activators, nucleating agents, and dyes.

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

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

[0019] In an embodiment of the present invention, the polypropylene resin molded article may be an inner coating material for an automobile communication cable. [Effects of the Invention]

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

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

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

[0023] 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, which may be obtained by stepwise polymerization of a matrix component of a propylene homopolymer or a propylene-ethylene or propylene-α-olefin random copolymer with an ethylene-propylene rubber copolymer component in a reactor.

[0024] The method for producing the ethylene-propylene block copolymer is not particularly limited, and any method for producing an ethylene-propylene block copolymer known in the art to which the present invention pertains may be used as is or with appropriate modifications. For example, the ethylene-propylene block copolymer may be produced by a polymerization method known to those skilled in the art in a commercialized process such as the Spherizone process of LyondellBasell, the Hypol process of Mitsui, or the Unipol process of Grace.

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

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

[0027] The xylene-soluble 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 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 ratio of the first polypropylene resin (A1) to the second polypropylene resin (A2) in the polypropylene resin (A) is in the range of 8.5:1.5 to 7.5:2.5. If the weight ratio of the first polypropylene resin (A1) to the second polypropylene resin (A2) is outside this 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 contain substantially only polypropylene-based resin (A) and may further contain components (B) to (D) described below, as necessary. Therefore, a polypropylene resin composition according to one embodiment of the present invention may contain 97.5 to 100 wt% of polypropylene-based resin (A) based on the total weight of components (A) to (D). Preferably, the content of polypropylene-based resin (A) in the polypropylene resin composition may be 98 to 99.5 wt%. If the content of polypropylene-based resin (A) in the polypropylene resin composition is less than 97.5 wt%, the low dielectric effect expected in the present invention may be reduced, or the effects of adding components (B) to (D) may not be further increased, making the composition uneconomical.

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

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

[0032] 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. Preferably, the antioxidant (B) may include pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate].

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

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

[0035] In an embodiment of the present invention, the long-term heat stabilizer (C) is selected from the group consisting of distearyl thiodipropionate, dilauryl thiodipropionate, dimyristyl thiodipropionate, ditridecyl thiodipropionate, 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 propionic acid 3,3'-thiobisdidodecyl ester. 3,3'-thiobisdidodecyl ester). Preferably, the long-term heat stabilizer (C) may include distearyl thiodipropionate.

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

[0037] (D) Neutralizer The polypropylene resin composition according to the implementation of the present invention may include a neutralizing agent (D).

[0038] In an embodiment 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 0 to 1.0 wt% of neutralizing agent (D) based on the total weight of components (A) to (D). When neutralizing agent (D) is included, residual components of the catalyst used in the production of polypropylene resin (A) can be effectively removed. However, if the content of neutralizing agent (D) exceeds 1.0 wt%, the effect of removing residual catalyst components does not increase any further, which may make the composition uneconomical.

[0040] (E) Additives The polypropylene resin composition according to the embodiment of the present invention may further contain conventional additives within the scope of the present invention, for example, 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 is no particular limitation on the method for producing the polypropylene resin composition according to the embodiment of the present invention, and any method for producing a polypropylene resin composition known in the technical field to which the present invention pertains can be used as is or with appropriate modifications, and the above-mentioned resin components and compounds can be freely selected and mixed according to a desired procedure without being restricted by a particular procedure.

[0042] Specifically, for example, the required amounts of the resins and compounds described above are mixed for 1 to 2 hours in a kneading machine such as a Henschel mixer, a kneader, a roll, or a 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 produced by molding the polypropylene resin composition of the present invention.

[0044] The method for producing a molded article from the polypropylene resin composition according to the embodiment of the present invention is not particularly limited, and any method known in the art to which the present invention pertains can be used. For example, the polypropylene resin composition according to the embodiment of the present invention can be molded by a conventional method such as injection molding, extrusion molding, or casting molding to produce a polypropylene resin molded article.

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

[0046] In an embodiment of the present invention, the polypropylene resin molded article may be an inner coating material for an automobile communication cable.

[0047] (Example) The present invention will be described in more detail below with reference to examples and comparative examples. However, the following examples are intended only to illustrate the present invention, and the scope of the present invention is not limited to these examples.

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

[0049] (Manufacturing example) Resins and compounds of the types and contents (unit: parts by weight) shown in Table 1 below were melt-blended at a temperature of about 180 to 210°C using a twin-screw extruder and pelletized. The pellets produced were co-extruded with electric wires and cables using a communication electric wire extruder to produce electric wires for communication, and the produced electric wires and cables were subjected to metal shielding and exterior coating to produce electric wires for automotive communication.

[0050] [Table 1]

[0051] (Test example) The electric wires for automobile communication obtained in each of the examples and comparative examples were tested by the following methods, and the results are shown in Table 2 below.

[0052] (1)Hardness A test piece with a thickness of 6 mm was injected, and 48 hours later, the hardness was measured using a Shore D hardness tester.

[0053] (2) Capacitance (KS C 3004) Capacitance refers to the degree to which an electric charge is stored between electrodes. In the case of shielded electric wire, electric charge accumulates between the wire cores or between the wire core and the shield layer, which causes noise during signal transmission, and this is called capacitance. A 50m sample of the measurement section of the electric wire to be measured was left in air at a temperature of 20±5°C and a humidity of 65±5%, and the capacitance was measured between A and B using an electrostatic capacitance measuring device (LCR meter) as shown in the diagram below. The measurement frequency was 1000Hz. JPEG2025126125000002.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). A sample of wire 10m or longer was taken, measured using a network analyzer, and then converted to a value for 1m of cable. The measurement frequency range was the same as the attenuation measurement range.

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

[0056] (5) Wire roundness The roundness of the manufactured electric wire was measured using a three-dimensional measuring machine.

[0057] [Table 2]

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

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

[0060] Therefore, the polypropylene resin composition according to the embodiment of the present invention can be effectively used as an inner coating material for automobile communication cables.

Claims

1. (A) a polypropylene-based resin, the polypropylene-based resin (A) comprises (A1) a first polypropylene-based resin and (A2) a second polypropylene-based resin, the first polypropylene resin (A1) has a melt index of 2.3 to 3.3 g / 10 min and a xylene-soluble content of 18 to 22 wt % when measured at 230°C under a load of 2.16 kg; the second polypropylene resin (A2) has a melt index of 1.5 to 2.0 g / 10 min and a xylene-soluble content of 13 to 17 wt % when measured at 230°C under a load of 2.16 kg; A polypropylene resin composition, characterized in that 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.

2. 2. The polypropylene resin composition according to claim 1, wherein the first polypropylene resin (A1) and the second polypropylene resin (A2) are each an ethylene-propylene block copolymer.

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

4. The polypropylene resin composition according to claim 3, 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.

5. The polypropylene resin composition according to claim 3, wherein the long-term heat 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-laurylthiopropionyloxy-methyl)methane, pentaerythritol tetrakis(3-dodecylthiopropionate), lauryl 3,3'-thiodipropionate, stearyl 3,3'-thiodipropionate, distearyl disulfide, and propionic acid 3,3'-thiobisdidodecyl ester.

6. The polypropylene resin composition according to claim 3, wherein the neutralizing agent (D) comprises at least one selected from the group consisting of calcium stearate and hydrotalcite.

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

8. 2. 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.

9. A polypropylene resin molded product produced by molding the polypropylene resin composition according to any one of claims 1 to 8.

10. 10. The polypropylene resin molded article according to claim 9, which satisfies the following conditions: a Shore D hardness of 58 to 65, a capacitance of 104±5 nF, a characteristic impedance of 50±2 Ω / km, and an attenuation amount of: 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; and Less than 1.59 dB / m at 3000 MHz.

11. The polypropylene resin molded article according to claim 9, which is an inner coating material for an automobile communication cable.

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