Crosslinkable polymer resin and method for preparing same

Abstract

Disclosed is a crosslinkable polymer resin comprising: (a) low-density polyethylene (LDPE); and (b) one kind of polyolefin (PO) selected from the group consisting of linear low-density polyethylene (LLDPE) and high-density polyethylene (HDPE), wherein a catalyst metal residue is 100 ppm or less. According to the present invention, mechanical properties are improved, chemical resistance is enhanced, thermal stability is increased, electrical insulation is maintained, and the content of a crosslinking agent can be reduced.

Description

Crosslinkable polymer resin and method for producing the same

[0001] The present invention relates to a crosslinkable polymer resin and a method for producing the same. More specifically, the present invention relates to an environmentally friendly crosslinkable polymer resin and a method for producing the same, which not only exhibits excellent mechanical properties, chemical resistance, and thermal stability even with a low crosslinking agent content, but also maintains electrical insulation properties while allowing for a reduced crosslinking agent content.

[0002] Crosslinked polymer resins, particularly crosslinked polyolefin resins, exhibit excellent mechanical strength and heat resistance through crosslinking, as well as high chemical resistance, making them stable under a variety of environmental conditions. Furthermore, they maintain flexibility and impact resistance, allowing them to be processed into various shapes. Their excellent electrical insulation properties make them suitable for use in power cables.

[0003] The high-voltage insulated cable industry is currently reducing the use of cross-linking agents due to industry demands and environmental concerns. However, reducing the use of cross-linking agents reduces the degree of cross-linking of cross-linked polyolefins, which reduces heat resistance, mechanical strength, and thermal stability. This reduces the lifespan of power cables and necessitates reduced power transmission capacity. This, in turn, leads to increased power loss and higher maintenance costs.

[0004] Research is underway to develop high-performance crosslinking agents and optimize the crosslinking process to maintain the properties of crosslinked polyolefin resins while reducing the amount of crosslinking agent used. In particular, there is a need for crosslinked polymer resins and methods for their production that improve mechanical properties and thermal stability by blending low-density polyethylene (LDPE) with polyolefins (PO) of different molecular structures.

[0005] Related prior art includes Korean Patent Registration No. 10-1959473.

[0006] The purpose of the present invention is to provide a crosslinkable polymer resin with improved mechanical properties and a method for producing the same.

[0007] Another object of the present invention is to provide a crosslinkable polymer resin having excellent chemical resistance and thermal stability and a method for producing the same.

[0008] Another object of the present invention is to provide a crosslinkable polymer resin that maintains electrical insulation properties and a method for producing the same.

[0009] Another object of the present invention is to provide an environmentally friendly crosslinkable polymer resin and a method for producing the same, which can reduce the content of a crosslinking agent.

[0010] The above and other objects of the present invention can all be achieved by the present invention described below.

[0011] 1. One aspect of the present invention relates to a crosslinkable polymer resin. The crosslinkable polymer resin comprises (a) low-density polyethylene (LDPE); and (b) one type of polyolefin (PO) selected from the group consisting of linear low-density polyethylene (LLDPE) and high-density polyethylene (HDPE), and has a catalyst metal residue of 100 ppm or less.

[0012] 2. In the above 1 specific example, the catalyst metal residue may be 0.1 to 95 ppm.

[0013] 3. In the above 1 to 2 specific examples, the polyolefin (b) may be 5 to 20 parts by weight based on 100 parts by weight of the low-density polyethylene (a).

[0014] 4. In the above 1 to 3 specific examples, the crosslinkable polymer resin may contain 0.5 to 2 wt% of a crosslinking agent-derived component.

[0015] 5. In the above 1 to 4 specific examples, the polyolefin (b) may contain 1 to 20 wt% of polypropylene (PP).

[0016] 6. In the above 1 to 5 specific examples, the melt index of the polyolefin (b) according to ASTM D1238 (2.16 kg load, 190 ℃) may be 1 g / 10 min or less.

[0017] 7. In the above 1 to 6 specific examples, the crosslinkable polymer resin may have a hot set of 100% or less, measured according to ANSI / ICEA S-121-733 and ICEA T-28-562, at 1.35 wt% or less of the crosslinking agent.

[0018] 8. In the above 1 to 7 specific examples, the extrusion load increase of the crosslinkable polymer resin may be 10% or less compared to low-density polyethylene (a) under extrusion conditions of 120°C and 30 rpm.

[0019] 9. In the above 1 to 8 specific examples, the loss tangent (tanδ) of the crosslinkable polymer resin at 90°C, 50 to 60 Hz, and 30 kV may be 0.0001 to 0.003, and the AC dielectric breakdown strength at 25°C, 50 to 60 Hz, and 2 kV / 30 s may be 40 to 70 kV / mm.

[0020] 10. Another aspect of the present invention relates to an insulated cable. The insulated cable comprises a cross-linked polymer resin according to any one of claims 1 to 9.

[0021] 11. Another aspect of the present invention relates to a method for producing a crosslinkable polymer resin. The method comprises the steps of extruding low-density polyethylene (LDPE), polyolefin (PO), and a crosslinking agent, wherein the extrusion is performed so as to satisfy a catalyst metal residue of 100 ppm or less, and the polyolefin (PO) is one selected from the group consisting of linear low-density polyethylene (LLDPE) and high-density polyethylene (HDPE).

[0022] 12. In the above 11 specific examples, the extrusion may apply an extruder filter having a three-dimensional network structure.

[0023] 13. In the above 11 to 12 specific examples, the polyolefin (b) may be 5 to 20 parts by weight based on 100 parts by weight of the low-density polyethylene (a), and the crosslinking agent may be 0.5 to 2 parts by weight based on 100 parts by weight of the crosslinkable polymer resin.

[0024] 14. Another aspect of the present invention relates to a method for reducing a crosslinking agent in a crosslinkable polymer resin. The method comprises a step of blending polyolefin (PO) into low-density polyethylene (LDPE) and extruding the blend, wherein the extrusion is controlled so that the catalyst metal residue is 100 ppm or less, and the polyolefin (PO) is one selected from the group consisting of linear low-density polyethylene (LLDPE) and high-density polyethylene (HDPE).

[0025] 15. In the above 11 to 14 specific examples, the crosslinkable polymer resin may have a hot set of 100% or less, measured according to ANSI / ICEA S-121-733 and ICEA T-28-562, at 1.35 wt% or less of the crosslinking agent.

[0026] 16. In the above 11 to 15 specific examples, the extrusion load increase of the crosslinkable polymer resin may be 10% or less compared to low-density polyethylene (a) under extrusion conditions of 120°C and 30 rpm.

[0027] 17. In the above 11 to 16 specific examples, the loss tangent (tanδ) of the crosslinkable polymer resin at 90°C, 50 to 60 Hz, and 30 kV may be 0.0001 to 0.003, and the AC dielectric breakdown strength at 25°C, 50 to 60 Hz, and 2 kV / 30 s may be 40 to 70 kV / mm.

[0028]

[0029] The present invention has the effect of providing an environmentally friendly crosslinkable polymer resin and a method for producing the same, which not only has excellent mechanical properties, chemical resistance, and thermal stability even with a small content of crosslinking agent, but also maintains electrical insulation and can reduce the content of crosslinking agent.

[0030] Hereinafter, the present invention will be described in more detail. In the present specification, where the terms "includes," "has," and "consists of," are used, other parts may be added, unless "only" is used. When a component is expressed in the singular, it also includes the plural, unless otherwise explicitly stated.

[0031] When interpreting a component, it is interpreted as including the error range even if there is no separate explicit description.

[0032] Hereinafter, a crosslinkable polymer resin and a method for producing the same according to an embodiment of the present invention will be specifically described.

[0033] The crosslinkable polymer resin according to the present invention comprises (a) low-density polyethylene (LDPE); and (b) one type of polyolefin (PO) selected from the group consisting of linear low-density polyethylene (LLDPE) and high-density polyethylene (HDPE).

[0034] (a) low-density polyethylene (LDPE)

[0035] Low-density polyethylene according to one specific example of the present invention has flexibility and resistance during the crosslinking process, thereby improving durability.

[0036] The melt index of the above low-density polyethylene according to ASTM D1238 (2.16 kg load, 190°C) may be about 5 g / 10 min or less. In a specific example, the melt index may be about 0.1 to 5 g / 10 min, for example, about 0.5 to 3 g / 10 min, preferably about 1 to 2 g / 10 min. In the above range, the mixture may be uniformly mixed, and the crosslinking reaction may proceed evenly, thereby improving the physical and mechanical properties.

[0037] The above low-density polyethylene may be an ethylene polymer having a density of about 0.88 to 0.925 g / cm3, preferably about 0.89 to 0.922 g / cm3, and more preferably about 0.895 to 0.921 g / cm3. Within the above range, the flexibility and processability of the crosslinkable polymer resin may be excellent.

[0038] The weight average molecular weight (Mw) of the above low-density polyethylene may be about 50,000 g / mol or more, preferably 80,000 to 300,000 g / mol. Within the above range, the crosslinkable polymer resin may exhibit excellent impact resistance, processability, etc.

[0039]

[0040] (b) polyolefin (PO)

[0041] According to one specific example of the present invention, the polyolefin includes (b1) linear low-density polyethylene and (b2) high-density polyethylene.

[0042] The melt index of the above polyolefin according to ASTM D1238 (2.16 kg load, 190°C) may be about 1 g / 10 min or less. In a specific example, the melt index may be about 0.1 to 0.9 g / 10 min, for example, about 0.2 to 0.8 g / 10 min, preferably about 0.4 to 0.7 g / 10 min. Within the above range, the polyolefin may be uniformly mixed, and the crosslinking reaction may proceed evenly, thereby improving physical and mechanical properties.

[0043] The polyolefin may be included in an amount of about 5 to 20 parts by weight based on 100 parts by weight of low-density polyethylene (a). In a specific example, the polyolefin (b) may be included in an amount of about 8 to 18 parts by weight, for example, about 10 to 15 parts by weight, based on 100 parts by weight of low-density polyethylene (a). Within the above range, a uniform crosslinking reaction may occur, resulting in an excellent balance of thermal stability and mechanical strength.

[0044]

[0045] (b1) Linear low-density polyethylene (LLDPE)

[0046] Linear low-density polyethylene according to one specific example of the present invention is linear low-density polyethylene characterized by the absence of long-chain branches, which can increase mechanical strength and improve chemical resistance.

[0047] The linear low-density polyethylene may be an ethylene polymer having a density of about 0.909 to 0.930 g / cm3, preferably about 0.910 to 0.929 g / cm3, and more preferably about 0.915 to 0.929 g / cm3. Within the above range, the crosslinkable polymer resin may have excellent thermal stability and mechanical properties.

[0048] The weight average molecular weight (Mw) of the linear low-density polyethylene may be about 50,000 g / mol or more, preferably about 80,000 to 300,000 g / mol. Within the above range, the crosslinkable polymer resin may exhibit excellent chemical resistance, uniform crosslinking reaction, thermal stability, and the like.

[0049]

[0050] (b2) High-density polyethylene (HDPE)

[0051] High-density polyethylene according to one specific example of the present invention can increase strength and hardness and maintain stable performance even in high temperature, high pressure, and chemical exposure environments.

[0052] The high-density polyethylene may be an ethylene polymer having a density of about 0.938 to about 0.97 g / cm3, preferably about 0.94 to 0.965 g / cm3, and more preferably about 0.942 to 0.962 g / cm3. Within this range, the mechanical properties, chemical resistance, etc. of the crosslinkable polymer resin may be excellent.

[0053] The weight average molecular weight (Mw) of the above high-density polyethylene may be about 100,000 g / mol or more, preferably about 200,000 to 500,000 g / mol. Within the above range, the crosslinkable polymer resin may exhibit excellent chemical resistance, impact resistance, thermal stability, and the like.

[0054]

[0055] According to one specific embodiment of the present invention, the polyolefin (b) may include polypropylene (PP). The polypropylene may be blended during the process of pre-polymerizing polypropylene and then polymerizing polyethylene. The polypropylene has excellent compatibility, high thermal stability, and can improve mechanical properties. In a specific embodiment, the polyolefin (b) may include about 1 to 20 wt% of polypropylene. For example, it may be about 4 to 18 wt%, preferably about 6 to 15 wt%, and more preferably about 8 to 12 wt%. When the polypropylene is included in the above range, the heat resistance of the crosslinkable polymer resin is improved, crystallinity is excellent, and mechanical properties, chemical resistance, and thermal stability can be improved.

[0056]

[0057] A crosslinkable polymer resin according to one embodiment of the present invention comprises the low-density polyethylene (a) and polyolefin (b), which can enhance mechanical properties such as flexibility, tensile strength, and impact resistance, and optimize thermal stability after crosslinking. Furthermore, the crosslinkable polymer resin can improve processability, thereby enhancing efficiency in the manufacturing process, and maximize chemical resistance and durability under various environmental conditions.

[0058] Additionally, in specific embodiments, the crosslinkable polymer resin may further include a crosslinking agent.

[0059] The crosslinking agent includes, but is not necessarily limited to, dicumyl peroxide (DCP), benzoyl peroxide (BPO), vinyltrimethoxysilane (VTMS), azobisisobutyronitrile (AIBN), and the like.

[0060] The crosslinking agent may be about 0.5 to 2 parts by weight based on 100 parts by weight of the crosslinkable polymer resin. In a specific example, the crosslinking agent may be about 0.7 to 1.8 parts by weight, for example, about 0.9 to 1.7 parts by weight, preferably, about 1 to 1.5 parts by weight, and more preferably, about 1.2 to 1.4 parts by weight. When a specific filter is used to control the catalyst metal residue to a low level, the catalyst metal lowers the activation energy of the crosslinking reaction, so the speed of the crosslinking reaction is accelerated, and the crosslinking effect can be obtained with a smaller amount of crosslinking agent, and the crosslinking efficiency can be improved. That is, chemical stability, mechanical strength, chemical resistance, and thermal stability can be improved while reducing the content of the crosslinking agent. In addition, the use of the crosslinking agent can be reduced, thereby reducing the manufacturing cost, and the environmental burden caused by the crosslinking agent can be reduced, making it environmentally friendly.

[0061] The crosslinkable polymer resin may further include additives such as antioxidants, scorch inhibitors, crosslinking promoters, stabilizers, processing aids, flame retardant additives, retarder additives, acids, inorganic fillers, and voltage stabilizers.

[0062]

[0063] The crosslinkable polymer resin may have a hot set of 100% or less, as measured in accordance with ANSI / ICEA S-121-733 and ICEA T-28-562, at a crosslinking agent content of about 1.35 wt% or less. In specific examples, the hot set may be about 50% to 100%, for example, about 65% to 90%, and preferably about 70% to 85%. Within this range, the crosslinkable polymer resin may exhibit excellent mechanical properties, chemical resistance, and the like.

[0064] Under extrusion conditions of about 120°C and about 30 rpm of the crosslinkable polymer resin, the extrusion load increase compared to low-density polyethylene (a) may be about 10% or less. In a specific example, the extrusion load increase may be about 3% to 9%, for example, about 3.2% to 8%, and preferably about 3.5% to 6%.

[0065] The loss tangent (tanδ) of the crosslinkable polymer resin at about 90°C, about 50 to 60 Hz, and about 30 kV may be about 0.0001 to 0.003. In specific examples, the loss tangent may be about 0.0001 to 0.002, for example, about 0.0001 to 0.0015, and preferably about 0.0001 to 0.001.

[0066] The crosslinkable polymer resin may have an AC dielectric breakdown strength of about 40 to 70 kV / mm at about 25°C, about 50 to 60 Hz, and about 2 kV / 30 s. In a specific example, the dielectric breakdown strength may be about 45 to 65 kV / min, for example, about 50 to 60 kV / min, and preferably about 55 to 60 kV / min.

[0067]

[0068] According to one embodiment of the present invention, the crosslinkable polymer resin has a catalyst metal residue of about 100 ppm or less. In a specific embodiment, the catalyst metal residue may be about 0.1 to 95 ppm, for example, about 0.5 to 80 ppm, preferably about 1 to 60 ppm, and more preferably about 5 to 30 ppm. When the catalyst metal residue exceeds about 100 ppm, it may cause conductivity, thereby reducing insulation, and the dielectric breakdown voltage may be lowered. In addition, thermal stability and chemical stability may be reduced, causing deformation, and the uniformity of the crosslinking reaction may be hindered, thereby weakening mechanical properties.

[0069]

[0070] Another aspect of the present invention relates to a method for producing a crosslinkable polymer resin. The method comprises a step of mixing and extruding the low-density polyethylene (LDPE), the polyolefin (PO), and the crosslinking agent. The extrusion is performed so as to satisfy a catalyst metal residue of about 100 ppm or less. The extrusion may be performed using an extruder filter having a three-dimensional network structure. In specific examples, the extruder filter having the three-dimensional network structure may include a candle filter, a sintered metal filter, a foam filter, a knitted wire mesh filter, a ceramic foam filter, etc., and is preferably a candle filter. Unlike a typical disk-type filter, the extruder filter has a large surface area and a multilayer structure, thereby improving filtration performance. In addition, the filter has high mechanical strength and durability, and in addition to its role of screening out foreign substances, it can effectively filter out metal catalysts.

[0071]

[0072] Another aspect of the present invention relates to an insulating cable comprising the cross-linked polymer resin described above. The cross-linked polymer resin has low electrical conductivity, which may be advantageous in minimizing heat generation in the insulating cable.

[0073] The above-described insulating cable may include an inner semiconductor layer, an outer semiconductor layer, and an insulating layer. The thickness of the insulating layer including the cross-linkable polymer resin may be about 1 to 200 mm. In a specific example, the thickness may be about 2 to 80 mm, for example, about 5 to 50 mm. Preferably, the thickness may be about 6 to 48 mm. Within the above range, the possibility of insulation layer destruction, durability, processability, and thermal stability degradation may be reduced.

[0074] The cross-linkable polymer resin may be mixed and applied in an amount of about 50 to 90 parts by weight, for example, about 70 to 90 parts by weight, and preferably about 80 to 85 parts by weight, for 100 parts by weight of the above-mentioned insulating cable. Within the above range, the bending characteristics of the power cable are not deteriorated, so flexibility is not reduced, and insulation, thermal stability, chemical resistance, and mechanical strength can be improved.

[0075]

[0076] Another aspect of the present invention relates to a method for reducing the crosslinking agent of a crosslinkable polymer resin. The method comprises a step of blending polyolefin (PO) into low-density polyethylene (LDPE) and extruding the blend, wherein the extrusion is controlled so that the catalyst metal residue is less than about 100 ppm, and the polyolefin (PO) is one selected from the group consisting of linear low-density polyethylene (LLDPE) and high-density polyethylene (HDPE).

[0077]

[0078] Hereinafter, the present invention will be described in more detail through examples and comparative examples; however, these examples are for the purpose of explanation only and should not be construed as limiting the present invention.

[0079]

[0080] Example

[0081] The components used in each of the examples and comparative examples below are as follows:

[0082] (a) LDPE: Density measured by ASTM D1505 is 0.921 g / cm3, MI (ASTM D1238, 2.16 kg load, 190°C) is 2.0

[0083]

[0084] (b1)LLDPE :

[0085] (b1-1) Density measured by ASTM D1505 is 0.920 g / cm3, MI (ASTM D1238, 2.16 kg load, 190°C) is 1.0

[0086] (b1-2) LLDPE with a density of 0.920 g / cm3 measured by ASTM D1505, MI (ASTM D1238, 2.16 kg load, 190°C) of 1.0, and 15% PP pre-polymerized during the polymerization process.

[0087]

[0088] (b2)HDPE:

[0089] (b2-1) Density measured by ASTM D1505 is 0.954 g / cm3, MI (ASTM D1238, 2.16 kg load, 190°C) is 1.0

[0090] (b2-2) The density measured by ASTM D1505 is 0.939 g / cm3, and the MI (ASTM D1238, 2.16 kg load, 190°C) is 0.19

[0091] (b2-3) LLDPE with a density of 0.954 g / cm3 measured by ASTM D1505, MI (ASTM D1238, 2.16 kg load, 190°C) of 1.0, and 15% PP prepolymerized during the polymerization process.

[0092]

[0093] DCP (Dicumyl Peroxide): Crosslinking agent

[0094] Sumilizer WX-RC (4,4'-Thiobis (2-tert-butyl-5-methylphenol)): Antioxidant

[0095]

[0096] Example 1

[0097] Among 100 wt% of total PE, 90 wt% of (a) LDPE and 10 wt% of (b2-1) HDPE with MI (ASTM D1238, 2.16 kg load, 190℃) of 1.0 were prepared. Afterwards, 1.35 wt% of DCP and 1650 ppm of Sumilizer WX-RC among 100 wt% of total crosslinkable polymer resin were uniformly mixed. Afterwards, the mixed sample was put into an extruder (Single Screw, 30 mmφ, L / D=25, 30 / 5 Die) and gradually heated and molten at 160℃, 170℃, 180℃, and 190℃ at 100 rpm to obtain XLPE.

[0098] A candle filter having a three-dimensional network structure was installed inside the above extruder, and the catalyst metal was filtered out while the sample was extruded.

[0099]

[0100] Example 2

[0101] The same procedure as Example 1 was followed, except that 85 wt% of (a) LDPE and 15 wt% of (b2-1) HDPE were used.

[0102]

[0103] Example 3

[0104] (b2-1) The same procedure as in Example 1 was followed except that (b2-3) HDPE containing 15 wt% PP was used instead of HDPE.

[0105]

[0106] Example 4

[0107] (b2-1) The same procedure as Example 1 was followed, except that (b2-2) HDPE with an MI (ASTM D1238, 2.16 kg load, 190°C) of 0.19 was used instead of HDPE.

[0108]

[0109] Example 5

[0110] (b2-1) The same procedure as Example 1 was followed except that 10 wt% of (b1-1)LLDPE was used instead of HDPE.

[0111]

[0112] Example 6

[0113] (b2-1) The same procedure as in Example 1 was followed, except that (b1-2) LLDPE containing 15 wt% PP was used instead of HDPE.

[0114]

[0115] Comparative Example 1

[0116] (a) The same procedure as Example 1 was followed, except that only 100 wt% of LDPE was used and no LLDPE or HDPE was used.

[0117]

[0118] Comparative Example 2

[0119] (b2-1) The same procedure as Example 1 was followed, except that only 100 wt% of HDPE was used and no LDPE was used.

[0120]

[0121] Comparative Example 3

[0122] (b1-1) The same procedure as Example 5 was followed, except that only 100 wt% of LLDPE was used and LDPE was not used.

[0123]

[0124] Comparative Example 4

[0125] _ The same procedure as Example 1 was followed, except that a Mesh Type Filter was used inside the extruder.

[0126]

[0127] The physical properties of the examples and comparative examples were evaluated using the following methods, and the results are shown in Tables 1 and 2:

[0128]

[0129] Physical property evaluation method

[0130] (1) Melt Index (g / 10min)

[0131] The measurement was performed using a TOYOSEIKI MELT INDEXER P-101 measuring device and with a piston load of 2.16 kg at 190°C in accordance with ASTM D1238.

[0132]

[0133] (2) Catalytic metal residue content (ppm)

[0134] The sample was dissolved in a solvent to prepare a solution, which was then introduced into the plasma torch as an aerosol using a sprayer. Argon gas was then used to generate a plasma of approximately 10,000 K, and the ionized sample was subjected to light separation using an inductively coupled plasma optical emission spectrometer (ICP-OES). The intensity of the light was measured at the detector, and the concentration of the metal component was calculated.

[0135]

[0136] (3) Hot Set (%)

[0137] Tests were conducted according to ANSI / ICEA S-121-733 and ICEA T-28-562 standards.

[0138] Samples were prepared, their initial lengths were measured, and heated in a 200°C oven for 15 minutes. A load of 20 N / cm2 was then applied to the specimens, the elongated length was measured, and the elongation was calculated. After cooling the samples to room temperature, their final lengths were measured, and the permanent strain was calculated to evaluate hot set.

[0139]

[0140] (4) Extrusion load increase (%)

[0141] The reference value was set by measuring the load in the extruder of LDPE (density measured by ASTM D1505 of 0.921 g / cm3, MI (ASTM D1238, 2.16 kg load, 2.0 at 190°C) at 120°C and 30 rpm. Afterwards, the load in the extruder of the sample was measured at 120°C and 30 rpm, and the load increase was expressed as a percentage compared to the reference load.

[0142]

[0143] (5) Loss tangent (tanδ)

[0144] An LCR meter (Agilent / Keysight) was used with conditions of 90°C, 50–60 Hz, and 30 kV. The sample was placed between parallel plate electrodes, and the LCR meter was operated to measure the dielectric constant (ε') and dielectric loss (ε'').

[0145] The above sample was manufactured in the form of a sheet having a diameter of 250 mm and a thickness of 0.5 mm using a hot press.

[0146] tanδ = ε'' / ε'

[0147] (The above ε' is the dielectric constant, and the above ε'' is the dielectric loss)

[0148]

[0149] (6) AC insulation breakdown strength (kV / mm)

[0150] The sample was placed between parallel plate electrodes, and an AC voltage was continuously increased to the sample at a voltage increase rate of 2 kV / 30 s at 25°C and 50 to 60 Hz, and the voltage at which the sample broke down was measured.

[0151] The above sample was manufactured in the form of a sheet having a diameter of 10 mm and a thickness of 0.5 mm using a hot press.

[0152] AC dielectric breakdown strength (kV / mm) = breakdown voltage (kV) / sample thickness (mm)

[0153]

[0154] (7) Aging Remaining Rate (%)

[0155] The initial tensile strength T0 of the samples was measured using ASTM D638 and exposed to a 150°C oven for 7 days. The samples were then cooled to room temperature, and the tensile strength T1 of the cooled samples was measured.

[0156] Aging residual rate = (T1 / T0) Υ 100

[0157] (The above T1 is the tensile strength after cooling at room temperature, and the above T0 is the initial tensile strength)

[0158] LDPE content (%)HDPE content (%)LLDPE content (%)Blend resin melt index (MI) 2.16 )PP content (%)Filter typeExample 19010010CandleExample 28515010CandleExample 390100115CandleExample 4901000.190CandleExample 59001010CandleExample 690010115CandleComparative Example 11000010CandleComparative Example 20100010CandleComparative Example 30010010CandleComparative Example 49010010Mesh

[0159] Catalyst Metal Residue (ppm)Hot Set (%)Extrusion Load Rise (%)Loss TangentAC Dielectric Breakdown Strength (kV / mm)Aging Residue (%)Example 1929950.0009556100Example 29178100.000815588Example 3917550.0008757102Example 49090100.000915695Example 5929840.0009156100Example 6937860.0009455100Comparative Example 19217000.0008156100Comparative Example 2911024500.001955476Comparative Example 3921123000.001975479 Comparative Example 420011650.005215398

[0160] As shown in Table 2 above, it can be confirmed that Examples 1-6 according to the present invention have improved mechanical properties, enhanced chemical resistance, increased thermal stability, and maintained electrical insulation properties compared to Comparative Examples 1-4 at the same crosslinking agent content.

[0161] Simple modifications or changes of the present invention can be easily implemented by a person having ordinary skill in the art, and all such modifications or changes can be considered to be included in the scope of the present invention.

Claims

1. (a) low-density polyethylene (LDPE); and (b) one kind of polyolefin (PO) selected from the group consisting of linear low-density polyethylene (LLDPE) and high-density polyethylene (HDPE); A crosslinkable polymer resin containing less than 100 ppm of catalyst metal residue.

2. In paragraph 1, A crosslinkable polymer resin having a catalyst metal residue of 0.1 to 95 ppm.

3. In paragraph 1, A crosslinkable polymer resin, wherein the polyolefin (b) is 5 to 20 parts by weight based on 100 parts by weight of the low-density polyethylene (a).

4. In paragraph 1, A crosslinkable polymer resin comprising 0.5 to 2 wt% of a crosslinking agent-derived component.

5. In paragraph 1, The above polyolefin (b) is a crosslinkable polymer resin containing 1 to 20 wt% of polypropylene (PP).

6. In paragraph 1, A crosslinkable polymer resin having a melt index of 1 g / 10 min or less according to ASTM D1238 (2.16 kg load, 190°C) of the polyolefin (b).

7. In paragraph 1, The crosslinkable polymer resin has a hot set of 100% or less as measured in accordance with ANSI / ICEA S-121-733 and ICEA T-28-562 at 1.35 wt% or less of a crosslinking agent.

8. In paragraph 1. A crosslinkable polymer resin, wherein the extrusion load increase is 10% or less compared to low-density polyethylene (a) under extrusion conditions of 120°C and 30 rpm.

9. In paragraph 1, A crosslinkable polymer resin having a loss tangent (tanδ) of 0.0001 to 0.003 at 90°C, 50 to 60 Hz, and 30 kV, and an AC dielectric breakdown strength of 40 to 70 kV / mm at 25°C, 50 to 60 Hz, and 2 kV / 30 s.

10. An insulating cable comprising a crosslinkable polymer resin according to any one of claims 1 to 9.

11. A step of extruding low-density polyethylene (LDPE), polyolefin (PO) and a crosslinking agent, The above extrusion is performed to satisfy the catalyst metal residue of 100 ppm or less, A method for producing a crosslinked polymer resin, wherein the above polyolefin (PO) is one selected from the group consisting of linear low-density polyethylene (LLDPE) and high-density polyethylene (HDPE).

12. In paragraph 11, The above extrusion is performed by applying an extruder filter having a three-dimensional network structure. A method for producing a crosslinkable polymer resin.

13. In paragraph 11, The polyolefin (b) is 5 to 20 parts by weight based on 100 parts by weight of the low-density polyethylene (a), A method for producing a crosslinkable polymer resin, wherein the crosslinking agent is 0.5 to 2 parts by weight based on 100 parts by weight of the crosslinkable polymer resin.

14. A method for reducing the crosslinking agent of a crosslinkable polymer resin, wherein the method Blend polyolefin (PO) into low-density polyethylene (LDPE) and extrude it. The above extrusion includes a step of controlling the catalyst metal residue to be 100 ppm or less, A method for reducing crosslinking agent of a crosslinkable polymer resin, wherein the above polyolefin (PO) is one selected from the group consisting of linear low-density polyethylene (LLDPE) and high-density polyethylene (HDPE).

15. In paragraph 14, A method for reducing crosslinking agent of a crosslinkable polymer resin, wherein the crosslinkable polymer has a hot set of 100% or less according to ANSI / ICEA S-121-733 and ICEA T-28-562 at 1.35 wt% or less of the crosslinking agent.

16. In paragraph 14, A method for reducing crosslinking agent of a crosslinkable polymer resin, wherein the extrusion load increase of the crosslinkable polymer resin is 10% or less compared to low-density polyethylene (a) under extrusion conditions of 120°C and 30 rpm.

17. In paragraph 14, A method for reducing a crosslinking agent of a crosslinkable polymer resin, wherein the crosslinkable polymer resin has a loss tangent (tanδ) of 0.0001 to 0.003 at 90°C, 50 to 60 Hz, and 30 kV, and an AC dielectric breakdown strength of 40 to 70 kV / mm at 25°C, 50 to 60 Hz, and 2 kV / 30 s.