KR20180137305A - Polypropylene compounds for an electric power cable - Google Patents

Abstract

The present invention relates to a polypropylene composite resin composition for an electric power cable, which contains a blend resin of 55 to 65 parts by weight of a reactive polypropylene and 35 to 45 parts by weight of a polypropylene block copolymer. The composition further contains 0.001 to 10 parts by weight of an additive with respect to the blend resin. An object of the present invention is to provide the polypropylene composite resin composition for the electric power cable, which can be stably operated at a high temperature.

Description

TECHNICAL FIELD [0001] The present invention relates to a polypropylene composite resin composition for a power cable,

TECHNICAL FIELD The present invention relates to a polypropylene composite resin composition for electric power cables, and more particularly, to an environmentally friendly polypropylene composite resin composition for electric power cables which can be stably used even at high temperatures.

Normally, a crosslinked polyethylene resin (XLPE) used as a mainstream as an insulating material of a power cable is excellent in heat resistance, chemical resistance, and electrical properties because it is a thermosetting resin. Methods for producing crosslinked polyethylene resins include crosslinking and electron beam crosslinking (US Patent No. 4426497, 1984.01.17) by a chemical reaction using an organic peroxide or silane (US Patent No. 6284178, Sep. 4, 2011) In the large wire industry, crosslinking by organic peroxide is the most widely used.

In addition, the power cable which is generally used at present is operated at a maximum temperature of 90 ° C. at all times, and the crosslinked polyethylene resin (XLPE) is used as the material of the insulating layer.

In recent years, it has been required to have a material for an insulation layer for a power cable made of a non-crosslinked polymer resin capable of being operated at a maximum permissible temperature of 110 ° C in order to satisfy the requirement of a power cable having a capability of being able to be recycled and having a high transmission capacity. .

On the other hand, since the crosslinked polyethylene resin is a thermoset resin produced by crosslinking polyethylene, it is impossible to recycle the resin, and therefore, it is difficult to dispose of the resin, and there is a problem that it causes environmental pollution. Further, since the melting point of the crosslinked polyethylene is 90 占 폚 to 115 占 폚, it is difficult to operate at a high temperature of 110 占 폚 and therefore, it is not suitable as an insulating layer material for power cables.

In this background, there is a prior art for non-crosslinked polyethylene resin in Korean Patent Laid-Open No. 10-2010-0106871 (2010.10.04) as a material of insulating layer for power cable, but in the actual processing, low shear thinning of resin is required, There is a problem in that the workability is poor and processing defects occur. In addition, there is a problem that the tracking resistance is poor and the performance as an insulator of an outdoor cable deteriorates.

Therefore, in order to solve such a problem, a variety of materials applicable to a power cable insulation layer made of a polymer composite resin having a high melting point so as to be stably maintained at a high temperature for a power cable have been studied.

An object of the present invention is to provide a polypropylene composite resin composition for a power cable which can be stably operated at a high temperature.

Another object of the present invention is to provide a polypropylene composite resin composition for a power cable excellent in heat resistance, flexibility, mechanical properties and electrical insulation.

Another object of the present invention is to provide a polypropylene composite resin composition for a power cable, which can be applied to various applications such as films, automobiles, and transparent containers, and which can be used stably for electric power cables.

According to one aspect of the present invention, embodiments of the present invention include a blend resin of 55 to 65 parts by weight of reactive polypropylene and 35 to 45 parts by weight of a polypropylene block copolymer, And 0.001 to 10 parts by weight of an additive to the polypropylene resin composition for a power cable.

The flexural modulus of the polypropylene composite resin composition may be 2000 kg / cm 2 to 4000 kg / cm 2. Further, the melting point may be from 160 캜 to 180 캜, and the melting index may be from 1 g / 10 min to 10 g / 10 min (230 캜).

The dielectric strength of the polypropylene composite resin composition may be 45 kV / mm or more, and the volume resistivity may be 10 ^{14 or} more. Preferably, the dielectric strength is 45 kV / mm to 65 kV / mm and the volume resistivity may be 10 ¹⁴ to 10 ¹⁷ .

The density of the polypropylene composite resin composition may be 0.8 g / cm 3 to 0.92 g / cm 3, and preferably the density may be 0.84 g / cm 3 to 0.90 g / cm 3.

The additive may be one or more of an antioxidant, a nucleating agent, and an acid-scavenger.

The heat capacity of the polypropylene composite resin composition is 2.0 J / K to 2.2 J / (g * K) at 25 ° C. and 2.6 J / (g * K) to 2.8 J / ).

The reaction type polypropylene comprises a polypropylene copolymer formed by polymerizing propylene monomer and at least one olefin comonomer selected from -olefins other than ethylene and propylene in the reactor, and a polypropylene copolymer formed by copolymerizing ethylene-propylene The rubber may be formed by chemical or physical bonding.

Wherein the polypropylene block copolymer comprises an ethylene-propylene block copolymer formed by stepwise polymerizing a propylene homopolymer in an amount of 65 parts by mass to 82 parts by mass and an ethylene-propylene rubber in an amount of 18 parts by mass to 35 parts by mass, The content of ethylene in the ethylene-propylene rubber may be 25 to 50 parts by weight.

The reaction type polypropylene has a melting point of 160 ° C or higher, a melting enthalpy of 20 J / g to 30 J / g, and a melt index of 0.5 g / 10 min to 2 g / 10 min.

The polypropylene block copolymer may have a melting point of 160 ° C or higher, a melting enthalpy of 50 J / g to 70 J / g, and a melt index of 3.0 g / 10 min to 4 g / 10 min.

The bending elastic modulus of the reactive polypropylene may be 500 kg / cm 2 to 1500 kg / cm 2, and the bending elastic modulus of the polypropylene block copolymer may be 8500 kg / cm 2 to 9500 kg / cm 2.

The tensile strength after heating (130 ° C, 240 hours) of the polypropylene composite resin composition may be 1.3 kg / mm 2 to 2.5 kg / mm 2, preferably after heating (130 ° C, 240 hr) 2.3 kg / mm < 2 >.

The elongation after heating (130 ° C, 240 hours) of the polypropylene composite resin composition may be 350% to 650%, and preferably, the elongation after heating (130 ° C, 240 hours) may be 400% to 600%.

INDUSTRIAL APPLICABILITY According to the present invention as described above, it is possible to provide a polypropylene composite resin composition for a power cable which can be stably operated at a high temperature.

Further, according to the present invention, it is possible to provide a polypropylene composite resin composition for a power cable excellent in heat resistance, flexibility, mechanical properties and electrical insulation.

Further, according to the present invention, it is possible to provide a polypropylene composite resin composition for a power cable which can be applied to various applications such as films, automobiles, and transparent containers, and which can be used stably for power cables in particular.

1 is a cross-sectional view of a power cable to which a polypropylene composite resin composition for a power cable of the present invention is applied.
2 is a photograph showing the crystal size of PP according to Example 1 of the present invention.
3 is a photograph showing the crystal size of PP according to Example 4 of the present invention.

The details of other embodiments are included in the detailed description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments described below, but may be embodied in various forms. In the following description, it is assumed that a part is connected to another part, But also includes a case in which other media are connected to each other in the middle. In the drawings, parts not relating to the present invention are omitted for clarity of description, and like parts are denoted by the same reference numerals throughout the specification.

The polypropylene composite resin composition for a power cable according to an embodiment of the present invention comprises 55 to 65 parts by weight of a reactive polypropylene and 35 to 45 parts by weight of a blend resin of a polypropylene block copolymer, And may further contain 0.001 to 10 parts by weight of additives to the blend resin.

The polypropylene composite resin composition may be prepared by blending reactive polypropylene and polypropylene block copolymer, which are polymeric resins prepared by different polymerization methods, in a predetermined content range.

Wherein the reaction type polypropylene comprises a polypropylene copolymer formed by polymerizing propylene monomer and at least one olefin comonomer selected from ethylene and an alpha -olefin other than propylene in a reactor, and an ethylene-propylene copolymer The rubber may be formed by chemical or physical bonding.

In an embodiment of the present invention, a homopolymer refers to a polymer having one type of repeating unit, and a copolymer means a polymer having two or more types of repeating units. For example, a heterophasic copolymer may be an ethylene-propylene rubber in which the rubber domain is dispersed in a matrix comprising a polypropylene homopolymer or a polypropylene copolymer.

For example, the reactive polypropylene may be a heterophasic copolymer and may be formed by chemically or physically bonding an ethylene-propylene rubber to a matrix of a polypropylene copolymer. The alpha -olefin comonomer may be of the formula CH ₂ = CH-R, where R is selected from the group consisting of H, 1-butene, 1-pentene, 4-methyl- , 1-dodecene, and mixtures thereof.

Specifically, the alpha -olefin comonomer comprises ethylene, the polypropylene copolymer is an ethylene-propylene copolymer, and the ethylene-propylene rubber may be branched to a polypropylene copolymer have. In addition, the ethylene-propylene copolymer may be a random copolymer in which comonomers are randomly dispersed according to polymer chains.

The reactive polypropylene may include at least one ethylene-propylene copolymer, for example, a propylene monomer may be a polypropylene resin in which an ethylene-propylene rubber (EPR) is dispersed in the reactor by polymerization with a catalyst. The reaction type polypropylene may further comprise a polypropylene copolymer formed by polymerizing propylene monomer and at least one olefin comonomer selected from -olefins other than ethylene and propylene in the reactor, - The propylene rubber may be formed by chemical or physical bonding.

The reactive polypropylene can improve the mechanical properties such as elongation and flexibility of the polypropylene composite resin composition and improve the whitening phenomenon.

The polypropylene block copolymer is a block copolymer prepared by applying an ethylene-propylene rubber, and 65 to 82 parts by weight of a propylene homopolymer and 18 to 35 parts by weight of an ethylene-propylene rubber are polymerized stepwise in the reactor And an ethylene content in the ethylene propylene rubber is 25 parts by weight to 50 parts by weight based on 100 parts by weight of the ethylene-propylene block copolymer.

The polypropylene block copolymer can improve mechanical properties such as tensile strength of the polypropylene composite resin composition.

In the polypropylene composite resin composition, the reactive polypropylene may be 55 to 65 parts by weight, and the polypropylene block copolymer may be 35 to 45 parts by weight.

When the reactive polypropylene is used in an amount of more than 65 parts by weight, the heat resistance is lowered and the heat strain rate is increased. When the polypropylene is used as an insulator for a power cable, it is difficult to use it for a long time at a high temperature, When the propylene block copolymer is used in an amount of more than 45 parts by weight, there arises a problem that rigidity is increased and flexibility is lowered and whiteing phenomenon occurs when it is used as an insulator for a power cable.

The melting polypropylene may have a melting point of 160 ° C or higher, a melting enthalpy of 20 J / g to 30 J / g, a melt index of 0.5 g / 10 min to 2 g / 10 min, and a melting point of the polypropylene block copolymer of 160 Deg. C, a melting enthalpy of 50 J / g to 70 J / g, and a melt index of 3.0 g / 10 min to 4 g / 10 min.

The flexural modulus of the reactive polypropylene may be 500 kg / cm 2 to 1500 kg / cm 2, and the flexural modulus of the polypropylene block copolymer may be 8500 kg / cm 2 to 9500 kg / cm 2.

The ethylene-propylene rubber contained in the reactive polypropylene may be the same as the ethylene-propylene rubber contained in the polypropylene block copolymer.

1 is a cross-sectional view of a power cable to which a polypropylene composite resin composition for a power cable of the present invention is applied.

Referring to FIG. 1, the polypropylene composite resin composition according to the present embodiment can be used as a material for an insulation layer in a power cable. The power cable may comprise at least one electrical conductor, an inner semiconductive layer sequentially disposed to surround the electrical conductor, an insulating layer comprising an insulator, an outer semiconductive layer, a neutral conductor watertight layer, a midline conductor and an outer conductor.

The insulation layer may be provided to improve the dielectric strength of the power cable and to improve the flexibility and flexibility of the power cable when the power cable is laid.

The polypropylene composite resin composition used as an insulator for the power cable may be prepared by blending a reaction type polypropylene and a polypropylene block copolymer. The reaction type polypropylene and the ethylene- The propylene rubber can be used as the same material. Thus, in the process of blending the reaction type polypropylene and the polypropylene block copolymer, the compatibility of these polymers can be improved and the mechanical properties of the polypropylene composite resin composition can be improved. Further, by using the same ethylene-propylene rubber, the reaction type polypropylene and the polypropylene block copolymer are uniformly mixed, thereby realizing excellent electrical characteristics at the interface of the insulating layer.

The polypropylene composite resin composition may further include 0.001 to 10 parts by weight of additives to the blend resin of the reactive polypropylene and the polypropylene block copolymer. The additive may be one or more of an antioxidant, a nucleating agent, and an acid-scavenger.

When the content of the additive is less than 0.001 parts by weight, weatherability and mechanical properties are decreased. When the additive is more than 10 parts by weight, electrical characteristics may be deteriorated.

The antioxidant includes a primary antioxidant and a secondary antioxidant. The primary antioxidant and the secondary antioxidant may be used individually. Preferably, the primary antioxidant and the secondary antioxidant are mixed Can be used.

Generally, the degradation of a polymer is caused by free radicals generated by heat, light, and mechanical shear in the main chain or sidewalls of the polymer, and the free radicals react with oxygen to form peroxide radicals. These peroxide radicals themselves decompose and react with other polymers and cause continuous autoxidation reactions.

The antioxidant may be added to prevent deterioration, oxidation, or discoloration of the blend resin. However, when an excessive amount of the antioxidant is added, the electrical characteristics may be deteriorated. Therefore, it is preferable to use a certain amount of the additive.

The antioxidant may include at least one of an amine type, a phosphite, a dialkyl ester type, a thio type, and a phenol type antioxidant. For example, the antioxidant may be selected from the group consisting of distearylthio-propionate, pentaerythrityl tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] Hydroxyphenyl) propanoyloxy] -2,2-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) Propanoyloxymethyl] propyl], 3- (3,5-di-t-butyl-4-hydroxyphenyl) propanoate, thiodiethylene bis (1,1-dimethylethyl) -4-hydroxybenzenepropanoic acid octadecyl ester, propionic acid, 3,3'-thiobis-1,1'-dioctadecyl ester And may include one or more.

The nucleating agent can control the size of crystals of the polypropylene contained in the polypropylene composite resin composition. The size of the crystal may affect the electrical characteristics of the polypropylene composite resin composition for a power cable. The number of crystals can be increased by adding the nucleating agent, whereby the size of the crystal is decreased to increase the density Electrical insulation and mechanical strength are increased.

The nucleating agent may be at least one of a sorbitol type and a nonitol type nucleating agent, and may be included in an amount of 0.07 wt% to 0.5 wt% with respect to the total weight of the polypropylene composite resin composition.

If the weight of the nucleating agent is less than 0.07% by weight, nucleophilic action by the nucleating agent is insufficient and the number of crystals formed is small, so that the crystal size becomes large and high transparency is not exhibited. The production cost is increased and the economical efficiency is a problem.

For example, the nucleating agent may be a sorbitol type nucleating agent such as benzylidene sorbitol, methylbenzylidene sorbitol, ethylbenzylidene sorbitol, 3,4-dimethylbenzylidene sorbitol and the like; And nonitol-based nucleating agents such as 1,2,3-trideoxy-4,6: 5,7-bis-O - [(4-propylphenyl) methylene] nonitol and the like.

The acid-scavenger may be provided to prevent degradation / decomposition of the polypropylene composite resin composition after aging, and examples thereof include cadmium stearate, barium stearate, calcium stearate, Strontium stearate, zinc stearate, lead stearate, aluminum stearate, magnesium stearate, and stannic stannate.

In the polypropylene composite resin composition, the flexural modulus may be 2000 kg / cm 2 to 4000 kg / cm 2. When the polypropylene composite resin composition is used as an insulating layer for a power cable, the bending elastic modulus needs to be kept within a predetermined range. When the bending elastic modulus is less than 2000 kg / cm 2, It is pressurized to interfere with the flow of electricity, and when the pressure exceeds 4000 kg / cm 2, the rigidity is high and the flexibility is lowered, so that it is difficult to bend the power cable.

In the polypropylene composite resin composition, the melting point may be from 160 캜 to 180 캜, and the melting index may be from 1 g / 10 min to 10 g / 10 min (230 캜). Further, the dielectric strength of the polypropylene composite resin composition is more than 45kV / mm, volume resistivity is 10 ^14, and be at least, preferably the dielectric strength is 45kV / mm to about 65kV / mm, volume resistivity is 10 ¹⁴ to 10 to ¹⁷ can work.

In addition, the dielectric strength and the volume resistivity of the polypropylene composite resin are included in the above-mentioned range, and when used as an insulator for a power cable, they can stably maintain electrical insulation properties at a high temperature for a long time.

The density of the polypropylene composite resin composition is 0.8 g / cm 3 to 0.92 g / cm 3, and preferably the density is 0.84 g / cm 3 to 0.90 g / cm 3.

The heat capacity of the polypropylene composite resin composition is from 2.0 J / (g * K) to 2.2 J / (g * K) at 25 ° C and from 2.6 J / * K).

The tensile strength after heating (130 ° C, 240 hours) of the polypropylene composite resin composition may be 1.3 kg / mm 2 to 2.5 kg / mm 2, preferably after heating (130 ° C, 240 hr) 2.3 kg / mm < 2 >.

In the polypropylene composite resin composition, if the tensile strength after heating is more than 2.3 kg / mm 2, the rigidity of the power cable becomes high when applied as an insulator of the power cable at a high temperature. If the rigidity of the power cable is less than 1.5 kg / .

The elongation after heating (130 ° C, 240 hours) of the polypropylene composite resin composition may be 350% to 650%, and preferably, the elongation after heating (130 ° C, 240 hours) may be 400% to 600%.

When the polypropylene composite resin composition is used as an insulator for a power cable, if the elongation after heating is less than 400% or exceeds 600%, the elasticity of the power cable is very low at a high temperature and is not suitable.

Hereinafter, examples and comparative examples of the present invention will be described. However, the following examples are only a preferred embodiment of the present invention, and the scope of the present invention is not limited by the following examples.

1. Preparation of Examples and Comparative Examples

Example  One

As shown in Table 1, a reaction type polypropylene (product name: Hifax CA 7441A, purchased from Lyondellbasell) and a polypropylene block copolymer (product name: CF335, purchased from Hanwha Total) were mixed in a ratio of 60:40 (Trade name: Iganox1010, purchased from CibaSC), a secondary antioxidant (product name: Irgafos 168, purchased from CibaSC) and a nucleating agent (product name: sorbitol type nucleating agent, milliken) as shown in Table 2 Purchase) was added to prepare Example 1. Here, the additives shown in Table 2 are amounts added based on the total weight ratio of the reaction type polypropylene and polypropylene block copolymer shown in Table 1. The physical properties were evaluated using the thus prepared Example 1 and shown in Table 3.

Example  2 to Example  4

As shown in Tables 1 and 2, the proportions of the reaction type polypropylene and the polypropylene block copolymer were different from those of the additives, and the remainder was prepared in the same manner as in Example 1, and the properties were evaluated.

Example  5 - Example  7

As shown in Table 4, only the ratio of the reaction type polypropylene and the polypropylene block copolymer was varied, and the remainder, such as the content of the additives, was prepared in the same manner as in Example 1 to evaluate its physical properties. Respectively.

Comparative Example  One

Except for using only reaction type polypropylene (product name: Hifax CA 7441A, purchased from Lyondellbasell) and using only primary and secondary antioxidants in the additives as shown in Table 1 and Table 2, The properties were evaluated and are shown in Table 3. < tb > < TABLE >

Comparative Example  2

The remaining conditions were the same as in Examples 1 and 2 except that only the polypropylene block copolymer (trade name: CF335, purchased from Hanwha Total) was used and only the primary and secondary antioxidants were used in the additives, as shown in Tables 1 and 2 The properties were evaluated and are shown in Table 3. < tb > < TABLE >

Comparative Example  3

As shown in Tables 1 and 2, the remaining conditions were the same as those of Example 1 except that only homopolypropylene (product name: HY301, purchased from Hanwha Total) was used and additives were not added, Table 3 shows the results.

Comparative Example  4

As shown in Tables 1 and 2, using a random polypropylene (product name: RP5061, purchased from PolyMirae) and random polypropylene (product name: RM5300, purchased from PolyMirae) in a ratio of 50:50 (weight ratio) Except that only the primary and secondary antioxidants were used in the same manner as in Example 1, and the properties thereof were evaluated.

Comparative Example  5

The remaining conditions were the same as in Example 1 except that only crosslinked polyethylene resin (trade name: LE4212, purchased from borealis) was used, and only the primary and secondary antioxidants were used in the additives, as shown in Tables 1 and 2 And the results are shown in Table 3.

Comparative Example  6 and Comparative Example  7

As shown in Table 4, only the ratio of the reaction type polypropylene and the polypropylene block copolymer was varied, and the remainder, such as the content of the additives, was prepared in the same manner as in Example 1 to evaluate its physical properties. Respectively.

Category (phr) Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 A 60 40 65 60 100 B 40 60 35 40 100 C 50 D 50 E 100 F 100

In Table 1, A represents a reaction type polypropylene resin (product name: Hifax CA 7441A, purchased from Lyondellbasell), B represents a polypropylene block copolymer (product name: CF335, purchased from Hanwha Total), C represents random polypropylene E is a homopolypropylene product (HY301, purchased from Hanwha Total), F is a crosslinked polyethylene resin (trade name: LE4212, borealis (trade name), purchased from Polymirae), D is random polypropylene (product name: RM5300, ).

Category (phr) Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 G 0.2 0.05 0.2 0.2 0.2 0.2 0.2 0.2 H 0.1 0.2 0.1 0.1 0.1 0.1 0.1 I 0.1 0.1 J 0.1

In Table 2, G is a primary antioxidant (product name: Iganox1010, purchased from CibaSC), H is a secondary antioxidant (product name: Irgafos 168, purchased from CibaSC), I is a sans cabin -Aldrich), and J is a nucleating agent (product name: sorbitol-based nucleating agent, purchased from milliken).

2. Method of measuring property

Evaluation of mechanical properties at room temperature

Each of the specimens prepared in Examples and Comparative Examples according to IEC-60811-501 was heated in an oven at 135 DEG C for 240 hours, and then the tensile strength and elongation at breaking point were measured at a rate of 25 mm / min.

Evaluation of mechanical properties at high temperature

Each of the specimens prepared in Examples and Comparative Examples according to IEC-60811-501 was heated in an oven at 135 DEG C for 240 hours, and then the tensile strength and elongation at breaking point were measured at a rate of 25 mm / min.

Here, the tensile residual rate and elongation percentage are calculated as (value after aging / value before aging) * 100, and the tensile residual rate and elongation percentage should be within a range of 80% to 120%, respectively.

density

The density at 23 [deg.] C was measured for each of the specimens prepared in Examples and Comparative Examples according to the IEC60811-606 standard.

Flexural modulus

Flexural modulus was measured for each of the specimens prepared in Examples and Comparative Examples according to ASTM D790 standard, and when the flexural modulus of 2,000 kg / cm 2 to 4,000 kg / cm 2 was exhibited, it was judged to be excellent in low temperature impact resistance, flexibility and flexibility.

AC insulation breakdown strength

The insulation breakdown voltage is measured in a transformer oil using a spherical electrode and the insulation breakdown voltage (V) divided by the thickness (d) is called an insulation breakdown strength (kV / mm). The higher the dielectric breakdown strength value, the better the electrical properties.

division Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Room temperature The tensile strength
(kg / mm2) 1.9 2.0 1.8 1.9 1.35 3.79 3.17 3.3 2.15 Elongation
(%) 595 560 630 610 630 940 23 839 510 heating The tensile strength
(kg / mm2) 2.1 2.2 1.8 2.0 1.45 3.3 2.73 2.45 2.09 Elongation
(%) 561 540 596 580 640 646 29 656 509 Tensile Residue
(%) 111 110 100 105 107 87 86 74 97 Elongation rate
(%) 94 96 95 95 102 69 126 78 100 density
(g / ml) 0.88 0.87 0.87 0.89 0.88 0.91 0.91 0.90 0.92 Flexural modulus (kg / cm ² ) 3300 3800 3100 3300 1000 7000 16000 15000 1500 AC insulation breakdown strength
(kV / mm) 64 60 59 62 51 58 60 61 50

FIG. 2 is a photograph showing the crystal size of the PP according to Example 1 of the present invention, and FIG. 3 is a photograph showing the crystal size of the PP according to Example 4 of the present invention.

The characteristics of Examples and Comparative Examples were examined with reference to Tables 1 to 3 as follows.

2 and 3, when Example 1 in which a nucleating agent was added as an additive and Example 4 in which a nucleating agent was not added was compared, it was found that the case of Example 1 was that the crystals of PP (polypropylene) And it can be confirmed that it is formed small. That is, in the case of Examples 1 and 4 in which the conditions other than the addition of the nucleating agent are the same, the size of the PP crystal is smaller and uniformly controlled in Example 1 in which the nucleating agent is added, . It was confirmed that the small and uniform formation of the PP crystals had an excellent effect on the electrical characteristics.

In the case of Comparative Example 1, only the reaction type polypropylene resin was used, and in Comparative Example 2, only the polypropylene block copolymer was used. Compared with Example 4, Comparative Example 1 was too low in flexural modulus of 1000 kg / cm 2 and was excessively flexible, which made it unsuitable for use as an insulator for electric power cables. Comparative Example 2 had excellent AC insulation breakdown strength, High tensile strengths of 3.79 kg / mm 2 and 3.3 kg / mm 2, respectively, are too rigid to bend for power cables, and the elongation percentage values are inadequate. That is, when only the reactive polypropylene resin or polypropylene block copolymer is used alone as in Comparative Example 1 or Comparative Example 2, the mechanical properties are not appropriate for use as an insulator for a power cable as in the embodiment of the present invention Can be confirmed.

In Comparative Example 3, only homopolypropylene was used alone. In Comparative Example 3, the AC insulation breakdown strength was excellent, but the flexural modulus was 16000 kg / cm < 2 > and the rigidity was so high that the bending property was poor and the elongation percentage was inadequate .

Comparative Example 4 was prepared by mixing random polypropylene of different kinds (different in mechanical properties with different molecular weights) in a ratio of 50:50. In the case of Comparative Example 4, even if different polypropylenes were mixed, the reaction type polypropylene resin and the polypropylene block copolymer were not mixed together as in the embodiments of the present invention. Therefore, the AC insulation breakdown strength was excellent but the flexural modulus 15000 kg / cm 2, the stiffness is too high, and the elongation percentage value is inadequate.

Comparative Example 5 uses a crosslinked polyethylene resin and has a flexural modulus of 1,500 kg / cm 2 and a high heat deformation rate at a high temperature, which is unsuitable because the power cable is pressed at a high temperature of 110 캜.

That is, when Comparative Example 1 to Comparative Example 5 were compared with Example 4 having the same additive content, when the reaction type polypropylene and the polypropylene block copolymer were mixed in a predetermined range as in Example 4, 1 to Comparative Example 5, it was confirmed that the insulator for power cable had excellent mechanical and electrical properties.

Example 1 showed excellent AC insulation breakdown strength, excellent tensile strength and elongation at room temperature and after heating, and excellent flexibility. Further, in Example 1, a nucleating agent was further added, and it was confirmed that small crystals of polypropylene were uniformly produced, and the electrical characteristics were excellent.

It was confirmed that Examples 2 and 3 have excellent AC insulation breakdown strength and excellent tensile strength and elongation properties at room temperature and after heating and excellent flexibility. Further, it was confirmed that Examples 2 and 3 each contain a sans cabin, and that the heat resistance and the weather resistance are good.

Example 4 showed excellent flexibility, AC breakdown strength, and excellent tensile strength and elongation at room temperature and after heating. On the other hand, as compared with Example 1, it was confirmed that Example 1 including a nucleating agent had a higher density and better AC insulation breakdown strength than Example 4.

Resin type
(unit) Example 1 Example 5 Example 6 Example 7 Comparative Example 6 Comparative Example 7 A (phr) 60 55 58 65 70 90 B (phr) 40 45 42 35 30 10 Heat Tensile Strength
(kg / mm2) 2.1 1.9 2.1 2.2 1.3 1.2 Heating elongation (%) 561 535 550 454 650 673

In Table 4, A is a reaction type polypropylene resin (product name: Hifax CA 7441A, purchased from Lyondellbasell), and B is a polypropylene block copolymer (product name: CF335, purchased from Hanwha Total).

Referring to Table 4, in Examples 5 to 7 and Comparative Examples 6 and 7, only the ratio of the reaction type polypropylene and the polypropylene block copolymer was changed, and the remaining conditions such as additives were the same as in Example 1 The results of heating tensile strength and elongation at break were confirmed.

As shown in Table 4, in the case of Examples 1 and 5 to 7 in which the contents of the reactive polypropylene resin and the polypropylene block copolymer were within the range of the present invention, the heating tensile strength and the elongation 1.5 kg / mm 2 and 400%, respectively. On the other hand, in the case of Comparative Example 6 and Comparative Example 7 which were outside the scope of the present invention, even when the additive was added in the same manner as in Example 1, it was confirmed that the heating tensile strength was poor at 1.4 kg / mm 2 or less. That is, if the content of the reactive polypropylene resin and the polypropylene block copolymer is within the range of the present invention, it can be used stably as a material for an insulator for a power cable operating at a high temperature of up to 110 ° C. I could confirm.

It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the foregoing detailed description, and all changes or modifications derived from the meaning and scope of the claims and the equivalents thereof are included in the scope of the present invention Should be interpreted.

Claims (18)

55 to 65 parts by weight of a reactive polypropylene and 35 to 45 parts by weight of a blend resin of a polypropylene block copolymer,
Further comprising 0.001 to 10 parts by weight of an additive with respect to the blend resin. The method according to claim 1,
And a bending modulus of elasticity of 2000 kg / cm 2 to 4000 kg / cm 2. The method according to claim 1,
Wherein the melting point is 160 占 폚 to 180 占 폚 and the melt index is 1 g / 10 min to 10 g / 10 min (230 占 폚). The method according to claim 1,
A dielectric strength of 45 kV / mm or more, and a volume resistivity of 10 ¹⁴ or more. The method according to claim 1,
Wherein the dielectric strength is 45 kV / mm to 65 kV / mm, and the volume resistivity is 10 ¹⁴ to 10 ¹⁷ . The method according to claim 1,
The density of the polypropylene composite resin composition for a power cable is from 0.8 g / cm 3 to 0.92 g / cm 3. The method according to claim 1,
The density of the polypropylene composite resin composition for a power cable is 0.84 g / cm 3 to 0.90 g / cm 3. The method according to claim 1,
Wherein the additive is at least one of an antioxidant, a nucleating agent, and an acid-scavenger. The method according to claim 1,
The heat capacity is from 2.0 J / (g * K) to 2.2 J / (g * K) at 25 ° C and from 2.6 J / (g * K) to 2.8 J / Composite resin composition. The method according to claim 1,
The reaction type polypropylene is a reaction-
A polypropylene copolymer formed by polymerizing propylene monomer and at least one olefin comonomer selected from -olefins other than ethylene and propylene in the reactor,
Wherein the ethylene-propylene rubber is chemically or physically bonded in the matrix made of the propylene copolymer. The method according to claim 1,
The polypropylene block copolymer may contain,
An ethylene-propylene block copolymer formed by stepwise polymerizing in a reactor from 65 to 82 parts by weight of a propylene homopolymer and from 18 to 35 parts by weight of an ethylene-propylene rubber,
Wherein the content of ethylene in the ethylene-propylene rubber is 25 parts by weight to 50 parts by weight. The method according to claim 1,
Wherein the reactive polypropylene has a melting point of 160 ° C or higher, a melting enthalpy of 20 J / g to 30 J / g, and a melt index of 0.5 g / 10 min to 2 g / 10 min. The method according to claim 1,
Wherein the polypropylene block copolymer has a melting point of 160 ° C or higher, a melting enthalpy of 50 J / g to 70 J / g, and a melt index of 3.0 g / 10 min to 4 g / 10 min. The method according to claim 1,
Wherein the reaction type polypropylene has a flexural modulus of 500 kg / cm 2 to 1500 kg / cm 2, and the polypropylene block copolymer has a flexural modulus of 8500 kg / cm 2 to 9500 kg / cm 2. The method according to claim 1,
And a tensile strength of 1.3 kg / mm < 2 > to 2.5 kg / mm < 2 > after heating (130 DEG C, 240 hours). The method according to claim 1,
The polypropylene composite resin composition for a power cable having a tensile strength of 1.5 kg / mm 2 to 2.3 kg / mm 2 after heating (130 ° C, 240 hr). The method according to claim 1,
And the elongation after heating (130 DEG C, 240 hours) is 350% to 650%. The method according to claim 1,
And the elongation after heating (130 DEG C, 240 hours) is 400% to 600%.

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