KR100239581B1 - Insulating material for electric wire - Google Patents

Abstract

a) 100 parts by weight of a non-polar polyolefin resin, a polar resin or a mixture thereof,

b) 70 to 120 parts by weight of non-toxic non-halogen flame retardant

c) 10 to 20 parts by weight of auxiliary flame retardant

d) 20 to 100 parts by weight of smoke density inhibitor

e) 5 to 30 parts by weight of a compatibilizer and

f) The flame retardant resin composition for cable coating containing 5-10 weight part of carbon black was disclosed. The flame-retardant resin composition for coating the wire cable has a feature that can significantly reduce the physical and physical damage caused by the smoke generated by the fire by significantly reducing the smoke density generated during the combustion.

Description

Flame Retardant Resin Composition for Wire Cable Covering

The present invention relates to a flame retardant resin composition for wire cable sheathing, and more particularly to a non-halogen non-toxic flame retardant resin composition having a very low smoke generation amount which can be used for wire cable sheathing.

Cables can be broadly classified into two types: communication cables and wire cables. Low-density, medium-density and high-density polyethylene are mainly used as the coating material for communication cables.They are flame-retardant for many years due to frequent fires in communication cables in many countries at home and abroad. The use of a communication cable using a resin composition is also active in Korea.

In the case of wire cables, the risk of a short circuit or a fire caused by an external flame is more serious than a communication cable. Therefore, polyvinyl chloride-based flame retardant resin composition is used as the wire cable coating material, and the polyvinyl chloride-based flame retardant resin composition generates a large amount of smoke and decomposition gas, which is extremely fatal to the human body during extrusion processing or combustion due to fire, and heat resistance. And because the cold resistance is weak, deformation of the summer product and mechanical properties are deteriorated, and the weak impact resistance at low temperatures and room temperature has been a major drawback in the long-term reliability of the cable for long-term use for decades. Accordingly, even in the case of the coating layer of the wire cable, the use of a non-toxic flame retardant composition using a non-halogen-based flame retardant having a small amount of smoke density generation without generating toxic gas during extrusion processing and fire should be in earnest.

In the case of the coating layer of the communication cable, the related art related to the non-halogen-based nontoxic flame retardant resin composition is as follows.

1) Korean Patent Publication No. 96-6148 discloses a flame retardant resin composition for coating a telecommunication cable, comprising a non-polar and polar polyolefin resin mixture, a metal hydroxide compound, a red, a compatibilizer, a surface treatment agent, and other additives. Described. The non-toxic flame retardant resin composition according to the embodiments described herein showed excellent room temperature tensile properties and oxygen index, but when the tensile properties test after heating, the low temperature conditions and low heating time of the wire cable coating layer requiring more excellent long-term heat resistance In this case, it is somewhat difficult to use. There is no specific reference to the thickness of the measurement specimen when measuring the smoke density, and when the cable is manufactured using the composition, the smoke density increases rapidly during combustion as the thickness of the coating layer increases.

2) Japanese Patent Laid-Open No. 63-56544 / 1988, Japanese Patent Laid-Open No. 184704/1987, and Japanese Patent Laid-Open No. 74138/1984

A composition for crosslinking comprising a low density polyethylene, ethylene ethyl acrylate copolymer, ethylene vinyl acetate copolymer mixture as a base resin, and a flame retardant such as aluminum hydroxide (Al (OH) ₃ ), magnesium hydroxide (Mg (OH) ₂ ), and red However, in the case of water crosslinking or irradiating crosslinking, it is impossible to function as a communication line by causing mechanical strength damage and thermal oxidation of the internal communication line under the influence of high temperature and moisture. In addition, irradiated crosslinking has a disadvantage in that it does not show uniform crosslinking characteristics as the thickness of the coating layer increases. The metal hydroxide compound in the cable coating layer made of the flame retardant composition is sensitive to moisture, heat, and pressure, and is not suitable for chemical crosslinking in vulcanization tubes requiring water crosslinking, high temperature, and high pressure.

3) US Patent 4,575,184 / 1986

An optical fiber cable is prepared by using a non-toxic flame retardant resin composition for irradiation crosslinking comprising a ethylene vinyl acetate copolymer as a base resin and containing a flame retardant such as a metal hydroxide compound, magnesium carbonate, calcium carbonate, and zinc borate, and a smoke density inhibitor. However, as described above, even in the communication and wire cable with a thick coating layer, it is possible to maintain a uniform degree of crosslinking, and thus, due to poor mechanical strength and high heat during crosslinking, metal hydroxide compound-based flame retardant decomposition may not be promoted to maintain flame retardancy. In addition, the smoke density shown in the embodiment is measured by the flamming method, and the thickness of the coating layer was also measured in a very thin state of 0.8 mm, which was not measured by a strict method similar to the actual conditions at the time of fire. In addition, the mechanical strength of the coating layer produced by the above composition has a drawback that is too low.

The non-toxic flame retardant coating layer according to the above inventions shows an excellent oxygen index, but has a drawback of generating a large amount of smoke during combustion in accordance with the increase of the coating layer in common.

Smoke generated during a fire makes it difficult to evacuate quickly, causing a lot of casualties due to suffocation, and the gas generated during combustion creates moisture that shows acidic contact with moisture. Not only damage, but also secondary property damage. Thus, stricter regulations on smoke density in the event of fire are being pursued in each country for indoor electrical appliances, office equipment products, building materials and cable sheathing materials.

Accordingly, an object of the present invention has a low smoke density during combustion that can greatly reduce the physical and physical damage caused by the smoke generated by the fire by dramatically reducing the smoke density generated during combustion compared to the conventional flame retardant resin composition. It is to provide a non-toxic flame retardant resin composition for wire cable coating.

As a result of our efforts to achieve the above object, the present inventors have added a compatibilizer, a non-halogen flame retardant, a secondary flame retardant, and a smoke density inhibitor to a non-polar polyolefin resin and a base resin of a polar resin, thereby providing low smoke density during combustion. It was found out that a non-toxic flame retardant resin composition for electric wire cable coating can be obtained, and completed the present invention.

Specifically, the flame retardant resin composition for electric wire cables of the present invention contains the following components:

a) 100 parts by weight of a non-polar polyolefin resin, a polar resin or a mixture thereof,

b) 70 to 120 parts by weight of non-toxic non-halogen flame retardant

c) 10 to 20 parts by weight of auxiliary flame retardant

d) 20 to 100 parts by weight of smoke density inhibitor

e) 5 to 30 parts by weight of a compatibilizer and

f) 5 to 10 parts by weight of carbon black.

As the a) base resin of the flame retardant resin composition of the present invention, a nonpolar polyolefin resin, a polar resin, or a mixture thereof was used. In the case where only the nonpolar resin is used alone, since the filling of the metal hydroxide compound and the smoke density inhibitor becomes poor, the mechanical strength and the cold resistance are greatly reduced, it is preferable to use a mixture with the polar resin.

Non-polar polyolefin resins used include low density polyethylene, linear low density polyethylene, medium density polyethylene, high density polyethylene, ethylene-propylene rubber, ethylene-propylene- having a melt index (MI) of 2.8 to 5.0 g / 10 min, as measured by ASTM D1238. A resin such as a diene rubber may be used, and as the polar resin, an ethylene vinyl acetate copolymer having a vinyl acetate content of 41% or less and a MI of 5 g / 10 minutes or less, an ethyl acrylate content of 35% or less and a MI of 5 g / Ethylene ethyl acrylate copolymers or mixtures thereof that are 10 minutes or less can be used.

In the present invention, b) magnesium hydroxide and aluminum hydroxide were used alone or in combination as a non-halogen flame retardant. Magnesium hydroxide has a good oxygen index at the same content as aluminum hydroxide, and is suitable for thermoplastic resins having a high processing temperature due to the decomposition temperature of 300 ° C. or higher. However, the smoke density generated during the combustion of the resin composition containing magnesium hydroxide has a significantly higher disadvantage than the smoke density generated during the combustion of the resin composition containing aluminum hydroxide.

Therefore, in the present invention, it is possible to lower the smoke density by using aluminum hydroxide having an average particle size of 0.6 to 2.0 μm, and to mix magnesium hydroxide having an average particle size of 0.6 to 2.0 μm to overcome poor processability and poor extrusion appearance. desirable. The addition amount of the metal hydroxide compounds is suitably 70 to 120 parts by weight based on 100 parts by weight of the base resin. If it exceeds 120 parts by weight, the mechanical properties are lowered and the smoke density is increased during combustion. The proportion of aluminum hydroxide in the mixture of the two metal hydroxide compounds is preferably 40 to 60%. If it is less than that, smoke density increases, and when it exceeds 60%, workability will worsen rapidly.

In the present invention, in order to supplement the flame retardancy, c) was used as an auxiliary flame retardant, which itself has a risk of self-ignition and explosion during processing, so that the melt index (MI) according to ASTM D1238 is 2 to 5 g / 10. 10 to 30 parts by weight of the masterbatch was prepared by using 100 parts by weight of low density polyethylene, linear low density polyethylene, high density polyethylene or ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, or mixtures thereof. The used master batch used 10 to 20 parts by weight based on 100 parts by weight of the base resin. Above 20 parts by weight, the smoke density rapidly increased.

In the present invention, d) the smoke density inhibitor was used to minimize the amount of smoke that can be generated during combustion. As the smoke density inhibitor used in the present invention, zinc borate, molybdenum compound (MoO ₃ ) or a mixture thereof having an average particle size of 1 to 3 μm was used. The zinc borate, molybdenum compound or mixtures thereof used above is suitably 20 to 100 parts by weight, preferably 40 to 100 parts by weight, relative to 100 parts by weight of the base resin. If it is more than 100 parts by weight, the mechanical properties are drastically reduced, and if it is less than 20 parts by weight, it does not function as a smoke density suppressor.

In addition, a) in order to improve the compatibility between the non-polar resin and the polar resin used as the base resin to increase the bonding strength at the interface and at the same time to increase the filling of the flame retardant and to maintain the mechanical strength of the composition, e) as a compatibilizer Low density polyethylene, linear low density polyethylene having a functional group content of 2.0 to 4.0 parts by weight, a density of 0.920 to 0.950 g / cm ^3, and a MI of 0.3 to 5.0 g / 10 minutes, such as maleic acid, methacrylic acid, citraconic acid, acrylic acid or anhydride thereof; 5 to 30 parts by weight of an adhesive polyethylene resin grafted with a functional group of medium density polyethylene or high density polyethylene was used based on 100 parts by weight of the base resin.

F) Carbon black used in the present invention is used for the purpose of improving the long-term weather resistance of the cable as a sunscreen when exposed to the outdoors, and the MI of the base resin is 5 to 10 g by using carbon black for improving weather resistance having an average particle size of 25 nm or less. 20 to 40 parts by weight based on 100 parts by weight of low density polyethylene, linear low density polyethylene, and 100 parts by weight of high density polyethylene were prepared and used, and the carbon black master batch used was 5 to 10 parts by weight of 100 parts by weight of the base resin. Parts by weight were used.

In the present invention, an antioxidant was used to impart thermal stability to the composition and cable manufacturing, and to prevent aging of the coating layer and to provide long-term thermal stability in the wire cable, which is highly self-heating due to conductor resistance during high voltage transmission and distribution. . Antioxidants used include octadecyl 3,5-di-t-butyl-4-hydrocinnamate, pentaerythryl-tetrakis [3- (3,5-di-t-butyl-4-hydroxy-phenyl ) Propionate], di (tridecyl) thiodipropionate, 2,4-thio-bis (6-t-butyl-3-methyl phenol) was used and 0.5 to 4 wt% based on 100 parts by weight of the base resin It is preferable to use a part.

In order to obtain the low smoke density non-toxic flame retardant resin composition of the present invention, a raw material may be mixed using a Henschel mixer, a ribbon blender, a V blender, or the like, or the raw materials may be supplied at different ratios using different raw material supply devices. Depending on the processing conditions, melt mixing may be carried out using a twin screw extruder, a twin screw extruder, or a twin screw extruder, kneader, mixer, or banbury mixer, in which a part of the extruder can be used as a feed in addition to a single feed port. Pellets were shaped. Since the physical properties of the resin composition change depending on the processing conditions, the screw rotation speed, supply amount and processing temperature are optimized by using a twin screw extruder that can use a part of the extruder as a supply port in addition to one supply port.

The low smoke density non-toxic flame retardant resin composition thus prepared was subjected to a constant water removal process to prepare compressed specimens, and measured mechanical properties, other smoke densities, and oxygen indexes according to the American Standard.

1) tensile strength

The breaking strength and elongation were measured by the method specified in ASTM D 638.

2) Tensile strength and elongation after heating

After compressing the compressed specimens in an oven maintained at 120 ° C. for 7 days, the breaking strength and elongation were measured.

3) oxygen index

Oxygen index was measured according to the method specified in ASTM D 2683.

4) Smoke density measurement

Smoke density was measured by the non-flemming method specified in ASTM E 662, and the specimen thicknesses were 0.5 mm and 4.0 mm.

Raw materials used in Examples and Comparative Examples are as follows.

1. LLDPE, Daelim Industrial Co., Ltd. Product: Name LL-04 ^{(density: 0.920 g / cm 3, MI} : 1.0 g / 10 min)

2.EVA, Mitsui Dupont: trade name EVA 260 (density: 0.950 g / cm ³ , MI: 6 g / 10 min, VA content 28%)

3.EEA, Neste: trade name NCPE 5710 (density: 0.930 g / cm ³ , MI: 1.0 g / 10 min, EA content 15%)

4. Mg (OH) ₂ , Kyowa Chemical Industry: trade name KISUMA 5A

5.Al (OH) ₃ , Alcoa: H-710

6. Zinc borate, Humprey Chemicals: ZB-325

7.MoO ₃ , Cherin Williams: trade name KEMGARD 981

8. Master batch, manufactured by Daelim Industrial Co., Ltd. using TP-10

9. Carbon Black Master Batch, using Cabot Vulcan 9A32, manufactured by Daelim Industrial Co., Ltd.

10. Adhesive Polyethylene, Daelim Industrial Co., Ltd. Product Name: SX-810 (High density polyethylene grafted with maleic anhydride)

11. Heat stabilizer, Yoshitomi: trade name YOSHINOX SR

Hereinafter, the present invention will be described in detail through examples and comparative examples of the present invention, but the present invention is not limited to the following examples and comparative examples.

Example

Example 1

75 parts by weight of magnesium hydroxide, 25 parts by weight of zinc borate, 10 parts by weight of a masterbatch, 0.8 parts by weight of antioxidant and 7.0 parts by weight of carbon black were added using an ethylene vinyl acetate copolymer as a base resin. After the flame retardant composition was prepared so that the actual resin temperature was 200 ° C. or lower, compression molded specimens were prepared according to ASTM D 1928. Tensile strength and elongation at room temperature were measured by the ASTM D 638 method, and the breaking strength and elongation were measured after a week of heat aging in a hot air dryer maintained at 120 ° C. Compression specimens were prepared in a uniform form (0.5 × 76 × 76 mm, 4.0 × 76 × 76 mm) according to ASTM E 662 to measure smoke density (non-flaming method) generated by radiant heat. In addition, a specimen for measuring oxygen index of 125 ± 5 mm in length, 6.5 mm ± 0.3 mm in width and 3 mm in thickness was prepared and measured according to the ASTM D 2638 method.

Physical property measurement results of the composition according to Example 1 are shown in Table 1 below.

Example 2

Except for using aluminum hydroxide instead of magnesium hydroxide was carried out in the same manner as in Example 1 and the results are shown in Table 1 below.

Example 3

Ethylene ethyl acrylate copolymer is used instead of ethylene vinyl acetate copolymer, and the molybdenum compound (MoO ₃ ) instead of zinc borate was used in the same manner as in Example 1 and the physical properties measurement results are shown in Table 1.

Example 4

The same procedure as in Example 3 except that aluminum hydroxide was used instead of magnesium hydroxide, and the results are shown in Table 1.

Comparative Examples 1 to 5

As in the composition ratio of Table 2, using the base resin, magnesium hydroxide or aluminum hydroxide alone, and did not use a smoke density inhibitor and a compatibilizer was carried out in the same manner as in Examples 1, 2, 3, 4 and the results Table 2 is as follows.

When comparing Examples 1, 2, 3, and 4 and Comparative Examples 1, 2, 3, 4, and 5, a mixture of zinc borate or molybdenum compound was used rather than using a flame retardant of magnesium hydroxide or aluminum hydroxide alone. It can be seen that the use caused a significant decrease in smoke density without a decrease in mechanical strength. In addition, it can be seen that the smoke density is lower when aluminum hydroxide is used than when magnesium hydroxide is used.

Examples 5-10

100 parts by weight of a mixture of LLDPE and EVA or EEA was used as a base resin, and 25 parts by weight of a compatibilizer, magnesium hydroxide or aluminum hydroxide was used alone or in a mixture, and zinc borate or molybdenum compound was used alone. The amount of the metal hydroxide compound and the zinc borate or molybdenum compound was used 185 parts by weight based on 100 parts by weight of the base resin and 0.8 parts by weight of antioxidant. The method for producing a flame retardant resin composition and the method for measuring physical properties are the same as in Example 1, and the measured results are shown in Table 1 below.

Example Furtherance One 2 3 4 5 6 7 8 9 10 LLDPE 20 35 30 30 30 30 EVA 100 100 80 65 EEA 100 100 70 70 70 70 SX-810 25 25 25 25 25 25 Mg (OH) ₂ 75 75 55 35 90 90 40 Al (OH) ₃ 75 75 55 70 90 50 ZINC BORATE 25 25 75 95 95 MoO ₃ 25 25 80 95 95 Master batch 10 10 10 10 10 10 10 10 10 10 Carbon Black Master Batch 7.0 7.0 7.0 7.0 7.0 7.0 7.0 7.0 7.0 7.0 YOSHINOX SR 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 Tensile Strength (Kg / cm ² ) 85 90 83 85 133 135 142 149 139 127 % Elongation 450 240 450 237 241 205 264 177 256 231 Tensile strength (Kg / cm ² ) Elongation (%) after heating at 120 ℃ for 7 days - - - - 121214 131174 137237 123151 128232 121200 Oxygen index 29 28 29 27 31 31 30 29 31 31 Non-flaming 0.5 mm4.0 mm 105107 100169 85155 76150 83131 57119 65124 55107 51105 61114

Comparative example Furtherance One 2 3 4 5 LLDPE 100 EVA 100 EEA 100 100 100 Mg (OH) ₂ 100 100 100 Al (OH) ₃ 100 100 ZINC BORATE MoO ₃ Master batch 10 10 10 10 20 Carbon Black Master Batch 7.0 7.0 7.0 7.0 7.0 YOSHINOX SR 0.8 0.8 0.8 0.8 0.8 Tensile Strength (Kg / cm ² ) 60 80 75 70 75 % Elongation 40 500 500 250 200 Tensile strength (Kg / cm ² ) Elongation (%) after heating at 120 ℃ for 7 days 5532 - - - - Oxygen index 28 31 31 30 33 Non-flaming 0.5 mm4.0 mm 147296 144270 145283 125245 141261

* Tensile strength and elongation after heating is the composition using EEA and EVA alone

In case of specimen, melt measurement is not possible

The flame retardant resin composition for coating a wire cable according to the present invention has the characteristics that can greatly reduce the physical and physical damages caused by the smoke generated in a fire by dramatically reducing the smoke density generated during combustion with excellent mechanical properties. .

Claims (7)

a) 100 parts by weight of a nonpolar polyolefin resin, a polar resin or a mixture thereof, b) 70 to 120 parts by weight of a non-toxic non-halogen flame retardant c) low density polyethylene, linear low density polyethylene, high density polyethylene, ethylene vinyl acetate copolymer, ethylene ethyl acryl D) zinc borate compound, molybdenum compound, or secondary flame retardant 10 to 20 parts by weight of a masterbatch prepared using 10 to 30 parts by weight of an enemy based on 100 parts by weight of one or more resin mixtures selected from the group consisting of late copolymers; A flame retardant resin composition for coating a wire cable comprising 20 to 100 parts by weight of a smoke density inhibitor as a mixture thereof and e) 5 to 30 parts by weight of a compatibilizer and f) 5 to 10 parts by weight of carbon black. The method of claim 1, wherein octadecyl 3, 5-t-butyl-4-hydrocinnamate, pentaerythryl-tetrakis [3- (3, 5-di-t-butyl-4-hydroxy-phenyl) Propionate], di (tridecyl) thiodipropionate and 0.5 to 4 parts by weight of an antioxidant selected from the group consisting of 2, 4-thio-bis (6-t-butyl-3-methyl phenol) Flame retardant resin composition, characterized in that. The method of claim 1, wherein the non-polar polyolefin resin is a low density polyethylene, linear low density polyethylene, medium density polyethylene, high density polyethylene, ethylene-propylene rubber, having a melt index (MI) of 1.0 to 5.0 g / 10 minutes measured by ASTM D 1238, Or at least one resin selected from the group consisting of ethylene-propylene-diene rubber. The polar resin of claim 1, wherein the polar resin is an ethylene vinyl acetate copolymer having a vinyl acetate content of 41% or less and a MI of 5 g / 10 minutes or less, an ethyl acrylate content of 35% or less and an MI of 5 g / 10 minutes or less. A flame-retardant resin composition characterized by using a rate copolymer or a mixture thereof. The flame retardant resin composition according to claim 1, wherein the non-toxic non-halogen-based compound is a mixture of aluminum hydroxide and magnesium hydroxide in which the proportion of aluminum hydroxide, magnesium hydroxide, or aluminum hydroxide in the mixture is 40 to 60%. The compatibilizer according to claim 1, wherein the compatibilizer comprises 2.0 to 4.0 parts by weight of maleic acid, methacrylic acid, citraconic acid, acyl acid or its anhydride, and has a density of 0.920 to 0.950 g / cm 3 and MI of 0.3 to 5.0 g / 10. Flame retardant resin composition characterized in that the low density polyethylene, linear low density polyethylene, medium density polyethylene, or high density polyethylene. The method of claim 1, wherein the carbon black uses a carbon black master batch prepared using 20 to 40 parts by weight based on 100 parts by weight of low density polyethylene, linear low density polyethylene, or high density polyethylene having a MI of 5 to 10 g / 10 minutes. Flame retardant resin composition.