KR20220090468A - Crosslinkable polyethylene resin with low dielectric loss and manufacturing method thereof - Google Patents

Abstract

The present invention provides a cross-linked polyethylene resin with low dielectric loss by crosslinking a low-density polyethylene resin having an extracted low-density polyethylene content of 15 wt% or less when 1 wt% low-density polyethylene is added to hexane and extracted at 60°C for 4 hours will do

Description

Cross-linked polyethylene resin with low dielectric loss and manufacturing method thereof {CROSSLINKABLE POLYETHYLENE RESIN WITH LOW DIELECTRIC LOSS AND MANUFACTURING METHOD THEREOF}

An object of the present invention is to provide a crosslinked polyethylene resin having a low dielectric loss.

Among polymer materials used as insulation materials for electric wires, polyethylene is a polymer material widely used as an insulation material for various electric wires because it has excellent electrical insulation properties as well as excellent mechanical properties, chemical resistance and workability. Polyethylene started to be used as an insulating material for power cables due to the above advantages, and then it became necessary to increase the heat resistance and withstand voltage characteristics of polyethylene to insulate power cables with higher voltages. Crosslinkable polyethylene (XLPE) with increased heat resistance and withstand voltage characteristics by adding crosslinking agents (Dicumyl Peroxide and 　 others) to polyethylene according to the above necessity began to be used in earnest from the mid-1960s.

Currently, cross-linked polyethylene is being used to replace paper or oil used as an insulating material for existing power cables, and is expanding the voltage range (for insulation of 154 - 354Kv and 500kV class power cables) as an insulating material for power cables.

Polyethylene, which is a base resin of the cross-linked polyethylene, can be mass-produced using a tubular reactor .

The production can be increased by increasing the temperature deviation for each section of the tubular reactor, but the molecular weight distribution (Poly dispersity index, PDI) of polyethylene is increased due to the high temperature deviation.

As the molecular weight distribution value increases, the content of the low molecular weight polyethylene resin increases, and as polar substitution materials such as initiators or other additives are combined with the low molecular weight polyethylene, a problem of having a relatively high dielectric loss occurs.

In addition, when cross-linked polyethylene produced by cross-linking is used as an insulating material, the dielectric loss according to temperature increases, so when used at high temperatures or when the temperature according to resistance increases, the dielectric loss is high, resulting in poor insulation performance or insulation It has the disadvantage of being destructive. That is, it causes a high dielectric loss according to an increase in temperature, which causes a problem in that insulation performance is deteriorated or insulation breakdown occurs.

Accordingly, a study on a polyethylene resin capable of providing a crosslinked polyethylene having a low dielectric loss value even at room temperature or high temperature and also providing the crosslinked polyethylene, a low density polyethylene resin capable of increasing the production of the polyethylene resin, and a method for manufacturing the same is urgently needed.

Korean Patent Laid-Open Publication No. 10-2006-0084515 (July 25, 2006)

The present invention is to provide a low-density polyethylene resin having a low dielectric loss.

In addition, the present invention is to narrow the molecular weight distribution of the low-density polyethylene resin, to prepare a low-density polyethylene having excellent mechanical properties and low dielectric loss characteristics, and to provide a cross-linked polyethylene resin using the same.

The present invention relates to a crosslinking prepared by crosslinking a low-density polyethylene resin having an extracted low-density polyethylene content of 15 wt% or less, preferably 10 wt% or less, and more preferably 5 wt% or less, when extracted in an excess of hexane at 60°C for 4 hours. A polyethylene resin is provided.

According to an aspect of the present invention, the low-density polyethylene may include a molecular weight distribution of 20 or less.

According to an aspect of the present invention, the low-density polyethylene may include a molecular weight distribution of 20 or less and a dielectric loss value according to ASTM D 150 of 40 x 10 ^-4 tan δ or less at 90°C.

According to an aspect of the present invention, the low-density polyethylene may include a molecular weight distribution of 15 or less.

According to an aspect of the present invention, the low-density polyethylene may include a molecular weight distribution of 15 or less, and a dielectric loss value according to ASTM D 150 of 10 x 10 ^-4 tan δ or less at 90°C.

According to an aspect of the present invention, the low-density polyethylene may have a weight average molecular weight of 70,000 g/mol or more.

According to an aspect of the present invention, the cross-linked polyethylene resin may include a dielectric loss value according to ASTM D 150 of less than 50 x 10 ^-4 tan δ at 90°C.

According to an aspect of the present invention, the cross-linked polyethylene resin may include a dielectric loss value according to ASTM D 150 of 40 x 10 ^-4 tan δ at 90° C. or less.

According to an aspect of the present invention, the cross-linked polyethylene resin may include a dielectric loss value according to ASTM D 150 of 30 x 10 ^-4 tan δ at 90° C. or less.

According to an aspect of the present invention, the cross-linked polyethylene resin may include a dielectric loss value according to ASTM D 150 of 10 x 10 ^-4 tan δ at 90° C. or less.

In one embodiment, the cross-linked polyethylene resin may have a dielectric loss value according to ASTM D 150 that satisfies the value of 90° C. and less than 10×10 ⁻⁴ tan δ at 25° C.

According to an aspect of the present invention, the low-density polyethylene may be polymerized in a tubular reactor having three or more reaction zones.

According to an aspect of the present invention, the difference between the highest temperature and the lowest temperature of the second reaction zone in the reaction zone may be 160 °C or less.

According to an aspect of the present invention, the difference between the highest temperature and the lowest temperature of the third reaction zone in the reaction zone may include that of 80 °C or less.

According to an aspect of the present invention, based on 100 parts by weight of the low-density polyethylene, 1 to 3 parts by weight of a crosslinking agent may be included in the cross-linked polyethylene.

In the present invention, polymerization is carried out in a tubular reactor having three or more stages of reaction zone, the difference between the maximum temperature and the minimum temperature of the second reaction zone of the reactor is in the range of 160 ° C. or less, and the maximum temperature of the third reaction zone of the reactor And the difference in the minimum temperature may be to provide a method for producing a low-density polyethylene resin that is polymerized in the range of 80 ℃ or less.

The low-density polyethylene resin is low-density polyethylene in which the content of the extracted low-density polyethylene is 15 wt% or less, preferably 10 wt% or less, more preferably 5 wt% or less, when low-density polyethylene is added to hexane in an amount of 1 wt% and extracted at 60 °C for 4 hours. It may be to provide a method for producing a polyethylene resin.

The present invention provides a low-density polyethylene having an extracted low molecular weight content of 15 wt% or less when extracted in hexane at 60° C. for 4 hours. can have the effect of being

In addition, the present invention can provide a low-density polyethylene resin having excellent mechanical properties and low dielectric loss characteristics by narrowing the molecular weight distribution of the low-density polyethylene resin.

In addition, by cross-linking the low-density polyethylene resin, it is possible to provide a cross-linked polyethylene resin having mechanical properties and low dielectric loss characteristics. That is, the cross-linked low-density polyethylene resin according to an embodiment may have a dielectric loss of less than 50 x 10 ^-4 tan δ, and may be less than or equal to 40 x 10 ^-4 tan δ, preferably less than or equal to 30 x 10 ^-4 tan δ. , and more preferably, a low-density cross-linked polyethylene resin having very low properties of 10 x 10 ^-4 tan δ or less could be prepared.

Hereinafter, the present invention will be described in more detail through the accompanying embodiments or examples. However, the following specific examples or examples are only a reference for describing the present invention in detail, and the present invention is not limited thereto, and may be implemented in various forms.

Also, unless defined otherwise, all technical and scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description herein is for the purpose of effectively describing particular embodiments only and is not intended to limit the invention.

Also, the singular forms used in the specification and appended claims may also be intended to include the plural forms unless the context specifically dictates otherwise.

Also, when a part "includes" a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated.

In addition, "room temperature" described in the present invention means a temperature range of 15 ℃ to 25 ℃.

Conventionally, in order to increase the production of the low-density polyethylene, the production can be increased by increasing the temperature deviation for each section of the tubular reactor, but due to the high temperature deviation according to the section of the tubular reactor, the molecular weight distribution (PDI) of the low-density polyethylene is increased and , which soon leads to an increase in the content of low-molecular-weight, low-density polyethylene. As the content of the low-molecular-weight low-density polyethylene resin increases as described above, as the low-molecular-weight low-density polyethylene is combined with polar substituted substances such as initiators or additives, the high molecular weight low-density polyethylene is combined with polar substituted substances. The present inventors have recognized that there is a problem with high dielectric loss due to increased polarity.

That is, even when the low-density polyethylene containing a large amount of low molecular weight is cross-linked to produce cross-linked polyethylene, the dielectric loss value of the cross-linked polyethylene is large, which greatly affects commercial use.

In order to solve the above problems, the present invention prepares a low-density polyethylene resin in which the content of the extracted low-density polyethylene is 15 wt% or less when hexane is extracted at 60° C. for 4 hours, and cross-linked using a cross-linking agent. In the case of cross-linked polyethylene , found that the decrease in dielectric loss according to ASTM D 150 occurs very small, and thus completed the present invention.

Therefore, the present invention produces a low-density polyethylene having an extracted low-density polyethylene content of 15 wt% or less when hexane is extracted at 60° C. for 4 hours and cross-links it using the same, whereby the dielectric loss according to ASTM D 150 is 50 x 10 ^-4 It may be less than tan δ, and may be less than or equal to 40 x 10 ^-4 tan δ, preferably less than or equal to 30 x 10 ^-4 tan δ, and more preferably less than or equal to 10 x 10 ^-4 tan δ. Eggplant was able to produce low-density cross-linked polyethylene resins.

The content of the low-density polyethylene to be dissolved may be 15 wt% or less, preferably 10 wt% or less, and more preferably 5 wt% or less.

The low dielectric loss factor is, when 1 wt% of low-density polyethylene is added to hexane and extracted at 60°C for 4 hours, the content of the extracted low-density polyethylene is 15 wt% or less A significant effect generated by crosslinking low-density polyethylene to be.

In addition, the low-density polyethylene according to an aspect of the present invention may have a molecular weight distribution (PDI) of 20 or less, preferably 15 or less, but is not limited thereto.

Since the low-density polyethylene of the present invention has the solubility range and satisfies the molecular weight distribution range, processability, mechanical properties, and dielectric loss lowering effect may be excellent.

The dielectric loss value may be less than 50 x 10 ^-4 tan δ at 90 °C, may be 40 x 10 ^-4 tan δ or less, preferably 30 X 10 ^-4 Tan δ or less, but more preferably may be 10 X 10 ^-4 Tan δ, but is not limited thereto.

In addition, according to an aspect of the present invention, the low-density polyethylene may have a molecular weight distribution of 20 or less and a dielectric loss value according to ASTM D 150 of 40 x 10 ^-4 tan δ or less at 90° C., specifically, the low-density polyethylene has a molecular weight The distribution is 15 or less, and the dielectric loss value according to ASTM D 150 may be 10 x 10 ^-4 tan δ or less at 90° C., but is not limited thereto.

In addition, according to an aspect of the present invention, the weight average molecular weight of the low-density polyethylene may be 70,000 g/mol or more, preferably 70,000 to 200,000 g/mol, but is not limited thereto.

As the low-density polyethylene satisfies the weight average molecular weight, it has excellent processability and may have excellent mechanical properties even after crosslinking.

The inventors of the present invention were able to prepare a crosslinked polyethylene having a very low dielectric loss value by polymerizing the low-density polyethylene, which is the base resin of the cross-linked polyethylene, by controlling the temperature range.

In order to polymerize the low-density polyethylene, polymerization may be performed in a tubular reactor or an autoclave reactor, but preferably, polymerization in a tubular reactor may be preferable.

The tubular reactor is a long tubular reactor, relatively easy to maintain, and has the advantage of relatively excellent reactor over-conversion among flow reactors, so it is suitable for polymerizing the low-density polyethylene.

In addition, according to an aspect of the present invention, the tubular reactor may have a reaction zone of three or more stages, and the tubular reactor may have a different minimum temperature and a maximum temperature for each stage.

By controlling the minimum and maximum temperature for each stage of the tubular reactor, when the low-density polyethylene is put into hexane and dissolved at 60° C. for 4 hours, the content of the extracted low-density polyethylene is 15 wt% or less To provide a low-density polyethylene resin can do.

The temperature of the first reaction zone of the tubular reactor may be 100 to 350 °C, but if a person skilled in the art uses a tubular reactor to prepare a low density polyethylene resin, the temperature is not limited thereto.

In the present invention, by controlling the temperature of the second reaction zone and the temperature of the third reaction zone of the tubular reactor, it is possible to manufacture low-density polyethylene having the above solubility conditions.

The temperature of the second reaction zone may be operated in a temperature range of 100 to 400 °C, and preferably, the highest temperature may be 330 °C or less and the lowest temperature may be 160 °C or higher, but is not limited thereto.

According to an aspect of the present invention, the temperature of the third reaction zone may be operated in a temperature range of 200 to 400 ℃, preferably, the highest temperature is 340 ℃ or less and the lowest temperature may be 240 ℃ or more, but limited thereto it's not going to be

In the present invention, by controlling the difference between the maximum temperature and the minimum temperature of the temperatures of the second reaction zone and the third reaction zone, low-density polyethylene having the above solubility range can be manufactured.

According to an aspect of the present invention, the difference between the highest temperature and the lowest temperature of the second reaction zone in the reaction zone is conventionally operated at more than 160 ° C. in the reactor, so that the molecular weight distribution shows a value of 25 or more, most of which is 30 or more. In the present invention, the resin of the present invention was provided by controlling the temperature to 140 ° C. or less, preferably 90 to 130 ° C.

In addition, according to an aspect of the present invention, the difference between the highest temperature and the lowest temperature of the third reaction zone in the reaction zone is conventionally operated at 100 ° C. or higher, but in the present invention, 20 to 80 ° C. Preferably 20 to 50 By operating at ℃, combined with the temperature range of the second reactor, it is possible to provide a low-density polyethylene having a reduced molecular weight of 20 or less, preferably 15 or less, in the molecular weight distribution of the present invention.

In the second reaction zone and the third reaction zone, the difference between the maximum temperature and the minimum temperature in the temperature range satisfies the above categories, so that the molecular weight and molecular weight distribution values of the low-density polyethylene can be effectively controlled, and at the same time, the solubility values are satisfied. A low-density polyethylene resin that can be provided.

Now, the method for producing the low-density polyethylene will be described in more detail.

According to an aspect of the present invention, the low-density polyethylene may be polymerized in a tubular reactor having three or more reaction zones, that is, first, second, and third reaction zones.

The difference between the maximum temperature and the minimum temperature of the second reaction zone of the reactor is 160 ° C. or less, and the difference between the maximum temperature and the minimum temperature of the third reaction zone of the reactor is 80 ° C. or less to be polymerized in the range, low density polyethylene resin It provides a manufacturing method of

First, the ethylene monomer is compressed through an extruder, then preheated and introduced into the first reaction zone.

The reaction pressure in the reaction zone may be 2,200 to 3,400 kg/cm ² , preferably 2,400 to 3,200 kg/cm ² , but is not limited thereto. When the reaction pressure is within the above range, phase separation of the polymerized polymer phase and the ethylene monomer phase occurs, thereby suppressing the occurrence of cross-linking of polyethylene on the low-density polyethylene.

In addition, the reaction temperature of the reaction zone represents the lowest point temperature and the highest point temperature in each reaction zone, and preferably, the lowest point temperature is 160 °C or higher and the highest point temperature is 330 °C or lower. As the temperature is satisfied, the process control of the polymerization reaction of ethylene is smooth.

Since the conditions of the second reaction zone and the third reaction zone of the reactor are described above, they are omitted.

The polyethylene may be polymerized by adding an additive selected from an organic peroxide and a molecular weight modifier to the ethylene monomer.

The organic peroxide initiator is tert-butylperoxypivalate, di-normal-butylperoxydicarbonate, tert-butylperoxy neodecanoate, tert-butylperoxy 2-ethylhexanoate, tert-butylperoxyacetate , tert-butylperoxybenzoate, di-tert-butyl peroxide, tert-butylcumyl peroxide, 1,3-bis(tert-butylperoxyisopropyl)benzene, di-tert-amyl peroxide, tert Sherry-amyl peroxide-2-ethylhexanoate, tert-amyl peroxypivalate, di-tert-hexyl peroxide, tert-hexyl peroxy-2-ethylhexanoate and tert-hexyl peroxide At least one selected from oxypivalate is preferable, and the organic peroxide can be used as a single material, but since efficiency as an initiator varies depending on temperature, two or more types are mixed for optimal efficiency in the entire temperature range inside the reactor so it can be used

In addition, the organic peroxide can be used after being diluted in a solvent for efficient operation of the initiator injection pump. In the present invention, a conventional solvent can be used, and the type is not particularly limited, and preferably isoparaffin, but However, the present invention is not limited thereto.

The total input amount of the organic peroxide may be 5% or less based on the weight ratio of the total input ethylene monomer, but is not limited thereto.

In addition, the molecular weight modifier may play a role of assisting to have a broad molecular weight distribution by controlling the molecular weight, and specifically, the total amount of the molecular weight modifier may be 3% or less by weight of the total input ethylene monomer, However, the present invention is not limited thereto.

In the preparation method of the present invention, a molecular weight modifier commonly used may be added, and the type of compound is not limited. Examples of conventional molecular weight modifiers are olefinic hydrocarbons such as acetone, propionaldehyde, methyl ethyl ketone, propane, propylene, 1-butene, isobutene, pentene, hexene, heptene, and octene. The molecular structure of these hydrocarbons may include a linear, branched or cyclic structure. The molecular structure of the molecular weight modifier may include a benzene structure, another double bond structure, an aldehyde, an ether, an ester, a carboxylic acid, an alcohol, a ketone, an amine, a sulfur and the like.

The low-density polyethylene resin prepared by the above method may satisfy the content of 15 wt% or less of the low-density polyethylene to be extracted when low-density polyethylene is added to hexane at a content of 1 wt% and extracted at 60 °C for 4 hours.

According to an aspect of the present invention, with respect to 100 parts by weight of the low-density polyethylene, 1 to 3 parts by weight of a crosslinking agent may be included for crosslinking to provide crosslinked polyethylene.

The crosslinking agent is an additive that must be used basically to increase the physical properties and heat resistance for the purpose of insulation under high pressure by crosslinking the insulator in the vulcanization tube when insulating high voltage power cables for outdoor use. It can be used alone or together with a crosslinking accelerator.

The most commonly used crosslinking agent is an organic peroxide such as dicumyl peroxide (DCP), ditertiary butyl peroxide or ditertiary butyl peracetate (TBPA), and the appropriate amount is used in 100 parts by weight of polyethylene of the total crosslinked polyolefin resin composition. It may be 1 to 3 parts by weight, but is not limited thereto.

In addition, the present invention may further include an antioxidant in the crosslinked polyethylene.

The antioxidant is not limited thereto as long as it is within the scope used by those of ordinary skill in the art. Specifically, the antioxidant may be any one or a mixture of two or more selected from hindered phenol-based antioxidants, phosphite-based antioxidants, lactone-based antioxidants, ethanolamine-based antioxidants, and HALS-based antioxidants, but is limited thereto it's not going to be

The appropriate amount of the antioxidant may be 0.1 to 0.4 parts by weight based on 100 parts by weight of the polyolefin, but is not limited thereto.

Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples. However, the following examples and comparative examples are merely examples for explaining the present invention in more detail, and the present invention is not limited by the following examples and comparative examples.

[How to measure]

(1) Molecular weight and molecular weight distribution: Weight average molecular weight (Mw) and number average molecular weight (Mn) were measured from Gel Permeation Chromatography (GPC), and molecular weight distribution (PDI) was calculated as Mw/Mn.

The GPC was measured with an Agilent PL-220 instrument, and Eluent_TCB (HPLC grade, Honeywell Co., Ltd., Trichlorobenzene with 0.0125% BHT) was used as the solvent. As a column, Guard + PL gel Olexis 2set (Agilent) was used, and the flow rate was 1.0 ml/min and the temperature was measured at 160°C.

(2) Low molecular weight content measurement: When low-density polyethylene powder (passed through a 50 mesh sieve) was put into hexane at a content of 1 wt% and extracted at 60° C. for 4 hours, the content of the extracted low-density polyethylene was measured.

(3) Dielectric loss: The dielectric loss was measured after applying 1KV and 1MHz to the low-density polyethylene 1 mm thick sample. The dielectric loss measurement at 90° C. was measured by putting a sample in a constant temperature chamber.

[Examples 1 to, Comparative Example 1]

A polyethylene resin was prepared in a tubular reactor having four reactors.

After preheating the ethylene monomer compressed through the compressor to the initial temperature of the reactor, it was injected into a tubular reactor consisting of four reaction zones.

The monomers were introduced into a main stream entering the first reactor and a side stream directly entering the second reactor, and were added in a weight ratio of 55:45. Propylene was used as the molecular weight control agent, and the input ratio of the main stream and the side stream was divided into 50:50 by weight. Polymerization conditions such as pressure and temperature in each stage reaction zone are shown in Table 1 below.

As the reaction initiator, tert-butylperoxybenzoate was used, and a polyethylene resin was prepared by introducing it through an inlet at the tip of each stage reaction area.

The low molecular weight of the prepared polyethylene was measured by the method described above, and is shown in Table 2.

With respect to 100 parts by weight of the polyethylene homopolymer, 0.2 parts by weight of 4,4'-thiobis(3-methyl-6-tert-butyl phenol) as an antioxidant is put into a single screw extruder, and is extruded at 180° C. or less to granulate. After that, 2 parts by weight of dicumyl peroxide (DCP) as a crosslinking agent was put into a Hensel mixer and impregnated at a temperature of 80° C. or less. Cross-linking molding was carried out at a temperature of 180° C. for 15 minutes with a high-temperature molding machine. Thereafter, the dielectric loss was measured by the method described above, and is shown in Table 2.

division Example 1 Example 2 Comparative Example 1 1st stage reaction area Minimum temperature (℃) 170 170 140 Maximum temperature (℃) 250 250 250 2-stage reaction area Minimum temperature (℃) 190 190 150 Maximum temperature (℃) 315 295 320 Temperature difference (℃) 125 105 170 3 stage reaction area Maximum temperature (℃) 305 290 320 Minimum temperature (℃) 250 260 230 Temperature difference (℃) 55 30 90 molecular weight modifier Propylene (kg/hr) 21.5 23.5 21.2 Polymerization pressure (kg/cm ² ) 2,650 2,450 2,550

Example 1 Example 2 Comparative Example 1 GPC number average molecular weight g/mol 10,273 12,577 7,690 weight average molecular weight g/mol 202,396 185,845 212,250 PDI (Mw/Mn) 19.7 14.8 27.6 Low molecular weight content measurement (wt%) 11 5 22 Dielectric loss (25℃, tan δ) 8 x 10 ^-4 5 x 10 ^-4 10 x 10 ^-4 Dielectric loss (90℃, tan δ) 36 x 10 ^-4 8 x 10 ^-4 50 x 10 ^-4

As described above, the present invention has been described with reference to specific matters and limited examples and drawings, but these are only provided to help a more general understanding of the present invention, and the present invention is not limited to the above embodiments, and the present invention is not limited to the above embodiments. Various modifications and variations are possible from these descriptions by those of ordinary skill in the art.

Therefore, the spirit of the present invention should not be limited to the described embodiments, and not only the claims to be described later, but also all those with equivalent or equivalent modifications to the claims will be said to belong to the scope of the spirit of the present invention. .

Claims (9)

A cross-linked polyethylene resin prepared by crosslinking a low-density polyethylene resin having an extracted low-density polyethylene content of 15 wt% or less when extracted in hexane containing 1wt% of low-density polyethylene at 60°C for 4 hours. The method of claim 1,
The low-density polyethylene has a molecular weight distribution of 20 or less and a dielectric loss value according to ASTM D 150 of 40 x 10 ^-4 tan δ or less at 90° C., a cross-linked polyethylene resin. 3. The method of claim 2,
The low-density polyethylene has a molecular weight distribution of 15 or less, and a dielectric loss value according to ASTM D 150 is 10 x 10 ^-4 tan δ or less at 90° C., a cross-linked polyethylene resin. The method of claim 1,
The weight average molecular weight of the low-density polyethylene is 70,000 g / mol or more, cross-linked polyethylene resin. The method of claim 1,
The cross-linked polyethylene resin has a dielectric loss value according to ASTM D 150 of 40 x 10 ^-4 tan δ at 90° C. or less, the cross-linked polyethylene resin. 6. The method of claim 5,
The cross-linked polyethylene resin has a dielectric loss value according to ASTM D 150 of 10 x 10 ^-4 tan δ at 90° C. or less, a cross-linked polyethylene resin. 7. The method of any one of claims 1 to 6 selected from
The crosslinked polyethylene resin is crosslinked by including 1 to 3 parts by weight of a crosslinking agent with respect to 100 parts by weight of the low density polyethylene, the crosslinked polyethylene resin. 8. The method of claim 7
The crosslinking agent will be an organic peroxide, crosslinked polyethylene resin. Polymerization is carried out in a tubular reactor having three or more reaction zones,
The difference between the highest temperature and the lowest temperature of the second reaction zone of the reactor is in the range of 160 °C or less,
The difference between the maximum temperature and the minimum temperature of the third reaction zone of the reactor is a method for producing a low-density polyethylene resin that is polymerized in the range of 80 ℃ or less,
When the low-density polyethylene resin is extracted in hexane containing 1wt% of the low-density polyethylene at 60°C for 4 hours, the content of the extracted low-density polyethylene is 15 wt% or less The method for producing a low-density polyethylene resin.