KR101094556B1 - Linear low density polyethylene polymers for crosslinkable cable and resin composition and crosslinkable cable by using the same - Google Patents

Abstract

The present invention relates to a linear low-density polyethylene polymer for crosslinked wires, a crosslinked resin composition for wires using the same, and a crosslinked wire manufactured by using the same, which reduces scorch defects and reduces shrinkage and hot / set characteristics of the wire. The present invention relates to a linear low density polyethylene polymer for excellent crosslinked wires, a water crosslinked resin composition for wires using the same, and a crosslinked wire made using the same.

When the linear low density polyethylene polymer for crosslinked electric wire according to the present invention is used in the polyethylene composition for medium and low voltage power lines for crosslinked outdoor use, the surface of the prepared wire becomes smooth, the shrinkage and hot / set characteristics are excellent, and the scorch is bad when the wire coating is formed. This reduces the effect.

Linear low density polyethylene, water bridge, water bridge wire

Description

LINEAR LOW DENSITY POLYETHYLENE POLYMERS FOR CROSSLINKABLE CABLE AND RESIN COMPOSITION AND CROSSLINKABLE CABLE BY USING THE SAME}

The present invention relates to a linear low-density polyethylene polymer for crosslinked wires, a crosslinked resin composition for wires using the same, and a crosslinked wire prepared using the same. More particularly, the scorch defect is reduced during wire coating molding, and shrinkage and hot The present invention relates to a linear low density polyethylene polymer for crosslinked wire having excellent / set characteristics, a water crosslinked resin composition for wires using the same, and a crosslinked wire produced using the same.

In general, water bridge outdoor low-voltage power cable refers to a overhead wire, that is, a simple structure wire which is made of a layer of a material having two functions of an insulator and a sheath on an electric wire consisting of only a conductor, and has an intermediate form between underground cable and overhead wire.

Outdoor low and medium voltage cables should be excellent in weatherability and oxidation resistance as a function of sheathing, as well as electrical characteristics such as withstand voltage characteristics in order to function as an insulator. For this purpose, the resin composition used in the manufacture of the existing low-medium-voltage power cable for outdoor use includes a crosslinking agent for imparting heat resistance by chemical crosslinking, but such a crosslinking agent may be prematurely decomposed in an extruder to form an early crosslinked material called scorch. . For this reason, the extrusion of the produced resin from the extruder is difficult and there is a problem that adversely affects the appearance and physical properties of the final product. Therefore, there is an urgent need for a technical supplement of a method for manufacturing a medium-low voltage power cable for outdoor use by a chemical crosslinking method in which the crosslinking agent is added.

To this end, in order to improve productivity, a method of impregnating silane in a resin composition instead of chemical crosslinking to allow silane to be grafted to polyethylene by chemical reaction in a single screw extruder, and extruded cable is exposed to moisture to crosslink is disclosed. (US Pat. No. 4117195).

Since the water crosslinking method of the present invention has a lower binding energy than chemical crosslinking method and it is difficult to exclude the influence of water as it passes through water, it is mainly limited to extrusion insulation of overhead lines and is used at a relatively low voltage (1kV) class. desirable. However, due to the unequal reaction of silane and polyethylene in the extruder during the manufacture of outdoor low and medium voltage power cables by silane impregnation, it is difficult to maintain the uniformity of the final product properties, and there is a problem that scorch occurs in long-term work as well as master batch When adding a stabilizer or carbon black of the form has a problem that even dispersion dispersion occurs. Much research has been done to overcome these technical shortcomings and it has been quite effective.

However, Korean Patent No. 0373852, which provides an invention for a black resin composition for polyethylene crosslinking, has a disadvantage in that a shrinkage ratio of an electric wire is large, and Korean Patent Invention No. 0377862 discloses an invention for a water-crosslinked flame retardant resin composition for power line insulation. It provides but has a big disadvantage of shrinkage. In addition, Korean Patent Invention No. 0619363 provides a silane-grafted polyolefin composition, but there is a disadvantage in that the hot / set characteristic variation is large, and an improvement on these technologies is required.

Accordingly, the first technical problem to be achieved by the present invention to solve the above problems is to provide a linear low density polyethylene polymer for crosslinked electric wire for solving the problems of the water crosslinking resin composition for the insulation of the medium and low voltage power cable for outdoor use, To provide a water-crosslinked resin composition for electric wires.

The second technical problem to be achieved by the present invention is to provide a water cross-linked wire manufactured using the water cross-linked resin composition.

As a means for solving the above technical problem, the linear low density polyethylene polymer for the crosslinked electric wire of the present invention has a melt index of 2.0 to 4.0 g / 10 minutes (measured at 190 ° C temperature and 2.16 kg load with ASTM D1238), 0.916 to Density of 0.924 g / cm 3, molecular weight distribution (MWD) of 4 to 8, weight average molecular weights ranging from 10,000 to 1,000,000 (average number of short chain branches) / (1000 carbons) of 10 to 30 and 5 to 13% by weight of butenes It includes -1, the linear low density polyethylene polymer particles are all passed through 4 mesh, the fraction of the linear low density polyethylene polymer particles passing through 12 mesh is characterized in that less than 0.05wt%.

As another means for solving the above-described technical problem, the water cross-linking resin composition according to the present invention is characterized in that it is prepared using the linear low density polyethylene polymer for the cross-linking wire.

As another means for solving the above-described technical problem, the water-crosslinked wire according to the present invention is characterized in that it was manufactured using the water-crosslinked resin composition for the wire.

When the linear low density polyethylene polymer for crosslinked electric wire according to the present invention is used in the polyethylene composition for medium and low voltage power lines for crosslinked outdoor use, the surface of the prepared wire becomes smooth, the shrinkage and hot / set characteristics are excellent, and the scorch is bad when the wire coating is formed. This reduces the effect.

In order to solve the above technical problem, the linear low density polyethylene polymer of the present invention has a melt index of 2.0 to 4.0 g / 10 minutes (measured at 190 DEG C with an ASTM D1238 at a load of 2.16 Kg), a density of 0.916 to 0.924 g / cm3, When the molecular weight distribution (MWD) is 4 to 8 and the weight average molecular weight is in the range of 10,000 to 1,000,000, (average number of short chain branches) / (1000 carbons) is 10 to 30, and 5 to 13 weight% of butene-1, The linear low density polyethylene polymer particles all pass through 4 meshes, and the fraction of linear low density polyethylene polymer particles passing through 12 meshes is characterized by 0.05 wt% or less.

Hereinafter, the present invention will be described in detail.

Linear low density polyethylene

The inventors have found that the molecular structure and pellet size of linear low density polyethylene should be specified in order to improve the formability, hot / set characteristics, and scorch balance of the crosslinked electric wire used for outdoor low and medium voltage cables. .

2.0 ~ 4.0g / 10min melt index of the present invention (measured at ASTM D1238, temperature 190 ℃, load 2.16kg), density of 0.916 ~ 0.924g / cm3, molecular weight distribution (MWD) of 4-8, weight average molecular weight These 10,000 to 1,000,000 ranges (average number of short chain branches) / (1000 carbons) are 10 to 30 and contain 5 to 13% by weight of butene-1, all of the linear low density polyethylene polymer particles must pass through 4 mesh, The linear low density polyethylene polymer having a fraction of 0.05 wt% or less of linear low density polyethylene polymer particles having passed through 12 meshes was prepared using a known production method in a known gas phase reactor.

It is preferable that it is 2.0-4.0 g / 10min, and, as for the melt index (measured by ASTM D1238 at 190 degreeC and load 2.16 kg) of linear low density polyethylene of this invention, it is more preferable that it is 2.5-3.5 g / 10min. If the melt index of linear low density polyethylene is less than 2.0 g / 10 min, the shrinkage ratio of the cross-linked wire becomes large. If the melt index exceeds 4.0 g / 10 min, the crosslinking degree of the cross-linked wire decreases, resulting in poor hot / set characteristics. Because the problem occurs.

The density of the linear low density polyethylene is preferably 0.916 to 0.924 g / cm 3. Products with a density of less than 0.916 g / cm3 of linear low density polyethylene are undesirable because they are too expensive to produce in known gas phase reactors and cause process troubles. Is too large and is not desirable.

The molecular weight distribution (MWD) of the linear low density polyethylene of the present invention is preferably 4-8. If the molecular weight distribution (MWD) of the linear low density polyethylene is less than 4, the hot / set characteristics of the crosslinked wire become poor, and it is not preferable. Therefore, it is not preferable.

The linear low density polyethylene of the present invention preferably has (average number of short chain branches) / (1000 carbons) of 10 to 30 when the weight average molecular weight is in the range of 10,000 to 1,000,000. When the linear low density polyethylene has a weight average molecular weight in the range of 10,000 to 1,000,000, (average number of short chain branches) / (1000 carbon) is less than 10, it is not preferable because the shrinkage increases when used in a crosslinked wire, and the weight average molecular weight of the linear low density polyethylene is not preferable. When in the range of 10,000 to 1,000,000, (average number of short chain branches) / (1000 carbons) is more than 30, the crosslinking degree is lowered, which is not preferable because the hot properties are deteriorated.

It is preferable that the linear low density polyethylene of this invention contains 5-13 wt% butene-1 as a comonomer. If the butene-1 content of the linear low density polyethylene is less than 5 wt%, the shrinkage ratio of the crosslinked wire becomes large, which is not preferable. If the butene-1 content of the linear low density polyethylene exceeds 13wt%, it is not preferable because it causes process trouble when made in a known gas phase reactor.

All linear low density polyethylene polymer particles of the present invention are preferably sized to pass through 4 meshes. It is not preferable to use particles that are large enough not to pass through the mesh to the crosslinked wire compound because crosslinking degree deviation occurs and the hot / set characteristics become worse. It is preferable that the fraction which passes 12 mesh in the linear low density polyethylene polymer particle of this invention is 500 ppm or less. If the fraction passing through the 12 mesh exceeds 0.05wt%, it is not preferable because scorch occurs in forming the crosslinked wire.

In addition, general polyethylene additives may be added to the polyethylene polymers of the present invention for application to a variety of polyethylene crosslinked wires. For example, a dye masterbatch, antioxidant, heat and light stabilizer, antistatic agent, lubricant, antiblocking agent, preservative, processing aid, slip agent, anti-sticking agent, pigment, flame retardant, foaming agent and the like can be added.

The manufacturing method of the resin composition for crosslinked electric wires using the linear low-density polyethylene polymer of this invention is not specifically limited, Any method, such as a well-known monosil method, a seaplace method, and a siloxane method, can be used. More specifically, wire coating is performed after dry blending linear low density polyethylene and known water crosslinking additives (unsaturated silane compound, water crosslinking catalyst, peroxide, etc.) using a commonly used tumbler mixer and Henschel mixer. Molding or dry mixing may be performed by applying additional melt mixing using a kneader such as an extruder, mixing roll, kneader, roll mill, banbury mixer, or the like, followed by wire coating molding.

In addition, antioxidants, neutralizing agents, stabilizers, lubricants, processing aids, colorants, flame retardants, surface treatment agents, foaming agents, ultraviolet absorbers and the like may be further added as necessary.

The evaluation method of the various physical properties adopted by the following example and the comparative example was performed by the following test method.

1) Melt index: ASTM D1238 method (measured at temperature 190 ℃, load 2.16kg)

2) Density: measured by ASTM D792 method

3) Molecular weight distribution and number of short chain branches (SCB): Measurement of the number of short chain branches per 1000 carbons

Measured by Polymer Laborotories, GPC-FTIR

K value: 14.1, Alpha: 0.725, Set flow rate: 1.00 ml / min,

Speed: e.g. Use conditions of 1.2659 cm / s

4) Hot Test: Hot Elongation measurement after passing 15 minutes under water load of 200 ° C and 20N / ㎠ for water cross-linked extruded specimen (standard width 4mm, length 20mm, thickness 1m)

5) SET test: Removes the load after hot test and measures the recovery rate of hot elongation after 5 minutes

6) Scotch stability: Measure the crosslinking degree according to time while mixing each composition at 180 ℃ and 50rpm using Brabender mixer and measure the time when crosslinking degree reaches 5%

7) Shrinkage rate: Shrinkage rate is measured after leaving the crosslinked wire at 130 ℃ for 2 hours.

8) Resin composition for water crosslinking: Mix linear low density polyethylene with water crosslinking additives (silane, silanol condensation catalyst, peroxide, etc.) using a 840 rpm Henschel mixer.

9) Wire sheathing for hand-crossing: Wire sheathing at 50m / min using screw extruder with 40mmF, L / D 28, head temperature 175 ℃

10) Water bridge: Expose the water bridge for 2 hours to the water bath at 95 ℃.

11) 4 mesh (ASTM E11) Unpaid fraction: The fraction that cannot pass when linear low density polyethylene particles are filtered through 4 mesh

12) 12 mesh (ASTM E11) passing fraction: The fraction passing through 12 mesh when the linear low density polyethylene particles

Example 1

1.9 parts by weight of vinyltrimethoxysilane, 0.075 parts by weight of dicumyl peroxide, 0.1 part by weight of dibutyl tin dilaurate, in 100 parts by weight of linear low density polyethylene (A1) having a melt index of 2.8 g / 10 minutes and a density of 0.920 g / cm 3. After mixing at 840 rpm for 8 minutes in Henschel mixer, it was evaluated under electric wire covering, hand bridge and physical property measurement conditions. The results are shown in Table 1.

Example 2

Except for using the linear low density polyethylene (A2) was carried out in the same manner as in Example 1 to obtain a composition and to measure the physical properties are shown in Table 1 the results.

Example 3

Except for using the linear low density polyethylene (A3) was carried out in the same manner as in Example 1 to obtain a composition and to measure the physical properties and the results are shown in Table 1.

Comparative example  One

Except for using the linear low density polyethylene (B1) was carried out in the same manner as in Example 1 to obtain a composition and to measure the physical properties are shown in Table 1 the results.

Comparative Example 2

Except for using the linear low density polyethylene (B2) was carried out in the same manner as in Example 1 to obtain a composition and to measure the physical properties are shown in Table 1 the results.

Comparative Example 3

Except for using linear low density polyethylene (B3) was carried out in the same manner as in Example 1 to obtain a composition and to measure the physical properties are shown in Table 1 the results.

Comparative Example 4

Except for using the linear low density polyethylene (B4) was carried out in the same manner as in Example 1 to obtain a composition and to measure the physical properties are shown in Table 1 the results.

Comparative Example 5

Except for using the linear low density polyethylene (B5) was carried out in the same manner as in Example 1 to obtain a composition and to measure the physical properties are shown in Table 1 the results.

Comparative Example 6

Except for using the linear low density polyethylene (B6) was carried out in the same manner as in Example 1 to obtain a composition and to measure the physical properties are shown in Table 1 the results.

Comparative Example 7

Except for using the linear low density polyethylene (B7) was carried out in the same manner as in Example 1 to obtain a composition and to measure the physical properties are shown in Table 1 the results.

Comparative Example 8

Except for using the linear low density polyethylene (B8) was carried out in the same manner as in Example 1 to obtain a composition and to measure the physical properties are shown in Table 1 the results.

Comparative Example 9

Except for using the linear low density polyethylene (B9) was carried out in the same manner as in Example 1 to obtain a composition and to measure the physical properties are shown in Table 1 the results.

Comparative Example 10

Except for using the linear low density polyethylene (B10) was carried out in the same manner as in Example 1 to obtain a composition and to measure the physical properties are shown in Table 1 the results.

[Table 1] Measurement results of the linear low density polyethylene

unit Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Linear Low Density Polyethylene A1 A2 A3 B1 B2 B3 B4 MI g / 10 minutes 2.8 2.9 2.8 1.1 10 3.2 3.4 density g / cm 3 0.919 0.920 0.920 0.920 0.923 0.938 0.922 Molecular weight distribution
(MWD) - 6.1 5.9 6.0 6.2 6.1 6.2 3.6 SCB / 1000C - 19.6 20.15 21.2 19.1 19.4 19.6 21.6 Butene-1 content wt% 9.1 9.0 9.3 9.2 7.5 6.2 9.2 4 mesh
Unpaid fraction wt% 0 0 0 0 0 0 0 12 mesh
Pass fraction wt% 0.01 0.02 0.01 0.02 0.03 0.02 0.01 Scorch
stability minute 70 75 80 60 65 70 65 Shrinkage % 2 3 3 7 3 8 4 Hot elongation % 45 70 25 70 190 60 185 Three elongations % -15 -5 -3 2 3 One 3

unit Comparative Example 5 Comparative Example 6 Comparative Example 7 Comparative Example 8 Comparative Example 9 Comparative Example 10 Linear Low Density Polyethylene B5 B6 B7 B8 B9 B10 MI g / 10 minutes 2.8 3.8 2.2 2.9 2.7 3.0 density g / ㎠ 0.919 0.923 0.922 0.920 0.918 0.923 Molecular weight distribution
(MWD) - 8.4 5.3 4.8 6.1 5.7 6.0 SCB / 1000C 20.1 6.2 30.5 18.2 17.6 19.3 Butene-1 content wt% 8.8 8.7 12.8 4 9.0 8.9 4 mesh
Unpaid fraction wt% 0 0 0 0 0 0 12 mesh
Pass fraction wt% 0.01 0.02 0.01 0.03 0.02 One Scorch
stability minute 60 55 60 75 55 25 Shrinkage % 6 9 3 8 2 3 Hot elongation % 70 55 195 80 210 60 Three elongations % -2 -3 5 -One 25 -3

Claims (3)

Melt index of 2.0 ~ 4.0g / 10min (measured at ASTM D1238 with temperature 190 ℃, load 2.16kg), density of 0.916 ~ 0.924g / cm3, molecular weight distribution (MWD) 4-8, weight average molecular weight 10,000 ~ (Average number of short chain branches) / (1000 carbons) in the range of 1,000,000 and 10-30 and 5 to 13% by weight of butene-1, the linear low density polyethylene polymer particles all pass through 4 mesh (ASTM E11), A linear low density polyethylene polymer for a crosslinked electric wire, wherein a fraction of the linear low density polyethylene polymer particles passing through 12 mesh (ASTM E11) is 0.05 wt% or less. A water crosslinking resin composition prepared using a linear low density polyethylene polymer for water crosslinking according to claim 1. A water crosslinked wire manufactured using the water crosslinking resin composition according to claim 2.