KR20090055310A - Non-crosslinked heat and oil-resistant electric cable - Google Patents

Abstract

A non-crosslinked heat and oil-resistant electric cable is provided to ensure fire retardant characteristic even if a flame retardant is not added, to use non-halogen-containing resin as a second insulating layer material, and to maintain thin thickness of a second insulating layer while ensuring high use temperature, extrusion property and oil resistance. A non-crosslinked heat and oil-resistant electric cable comprises a conductor, a first insulating layer containing the conductor, and a second insulating layer containing the first insulating layer. The first insulating layer is made of polyolefin resin. The second insulating layer is selected from the group consisting of polyetheretherketone, polyimide and polyphenylene sulfide. The polyetheretherketone has a number average molecular weight of 70,000-110,000 and is poly(oxy-1,4-phenylene-oxy-1,4-phenylene-carbonyl-1,4-phenylene).

Description

Non-crosslinked heat and oil-resistant electric cable

The present invention relates to a high heat resistance and high oil resistance wire having a double insulation layer structure. More specifically, the present invention relates to a high heat and high oil resistance electric wire using polyether ether ketone, polyimide or polysulfide phenylene resin as a secondary insulating layer material.

1 is a schematic cross-sectional view of an insulated wire having a double insulation layer structure. In a double-insulated wire, the primary insulating layer serves as the basic and intrinsic insulation function, and the secondary insulating layer complements the primary insulating layer that is faithful to this basic insulating performance. In other words, the secondary insulation layer plays an additional role of complementary insulation function in case of primary insulation layer breakdown, oil resistance, heat resistance, fire resistance and cold resistance enhancement. Wire having only a single insulating layer made of the material of the secondary insulating layer may be excellent in oil, heat, fire, cold resistance, etc., but the most basic and important insulation function is weak.

Modern aircraft, military equipment, and ship equipment are equipped with a large number of electronic devices, and a large amount of wires are required to operate this equipment. Therefore, it is preferable to use a wire as small as possible, but the problem is that the heat generation is increased. The high temperature in plastic insulation material can cause the conductor to be exposed to damage of the coating material by heat in the short term and the durability deterioration due to heat aging of the coating material in the long term.

As such, the weight reduction and heat resistance of aerospace, military and marine cables are important challenges facing cable materials for this field. Therefore, in the industry, the material of the secondary insulating layer is composed of functional polymers, and efforts have been made to impart demanding physical properties required for electric wires in the ship and aviation industries. In this field, polymer resins having high glass transition temperature (T _g ), melting point (T _m ) and heat distortion temperature (Heat Distortion Temperature, HDT) have been used as heat-resistant materials for secondary insulation layers. Fluorine resins are typical. .

The fluororesin is a synthetic resin having a structure in which some or all of the hydrogen of the polyolefin resin structure is replaced with a fluorine atom. It has non-adhesiveness, non-oiliness, low friction coefficient, high electrical property and chemical resistance, and heat resistance at temperatures of about 120 ℃ ~ 250 ℃. Among the fluorine resins of the prior art, polyvinylidene fluoride (PVDF) and ethylene tetrafluoroethylene (ETFE) are widely used as insulation materials.

PVDF has excellent processability, which enables injection molding and extrusion molding, and has non-tackiness and corrosion resistance. For example, Korean Patent Laid-Open Publication No. 2001-79751 discloses an electric wire composed of an ethylene resin primary insulating layer and a PVDF secondary insulating layer containing a carbonyl group. However, PVDF has the lowest heat resistance and low wear resistance among fluorocarbon resins with a continuous use temperature of 120 ℃. Since PVDF has to undergo irradiation crosslinking process to improve heat resistance and room temperature characteristics, it takes a lot of cost and time in this process, and it is difficult to find a crosslinking irradiation condition that satisfies optimal properties. In addition, there is a disadvantage that the insulating properties are not uniform depending on the degree of crosslinking.

ETFE has excellent characteristics such as electrical insulation, abrasion resistance, heat resistance, etc., but the continuous use temperature is relatively low at 150 ℃. However, EFFE has a disadvantage in that the crosslinking reaction cannot proceed due to steric hindrance due to fluorine atoms due to the molecular structure of the repeating unit CF ₂ CF ₂ CH ₂ CH ₂ , and thus it is difficult to improve the continuous use temperature like PVDF. .

In addition, fluorine resin has a limit that the position is narrower than before in the tendency to tighten regulations on flame-retardant materials containing halogen element.

Therefore, the demand for high heat-resistant wire that has stable physical properties after extrusion and does not require a crosslinking process of a secondary insulating material has been difficult to fill sufficiently with the prior art. Overcoming the limitations of the prior art, these wires are expected to be useful not only in the ship and aerospace industries described above, but also in all other fields that require a thin insulation thickness and heat resistance and flexibility.

The technical problem of the present invention is to develop a high heat resistant wire having a secondary insulating layer made of an insulating material that does not require a crosslinking process. The secondary insulating material, which is a development target of the present invention, ensures sufficient insulation even at a thin thickness, and satisfies heat resistance and oil resistance satisfying the criteria set forth in Part 18 of the Defense Standard 61-12. shall.

In order to achieve the above technical problem, the present invention provides a double insulation structure having a primary insulation layer made of a polyolefin material and a secondary insulation layer made of a polymer selected from the group consisting of polyether ether ketone, polyimide, and polyphenyl sulfide. Provides high heat and oil resistant wire.

In the wire of the present invention, the polyether ether ketone preferably has a number average molecular weight of 70,000 to 110,000, more preferably the polyether ether ketone is poly (oxy-1,4-phenylene-oxy-1,4 -Phenylene-carbonyl-1,4-phenylene).

In the electric wire of the present invention, the polyimide is preferably Ultem or Extem resin.

The high heat resistant and oil resistant electric wire of this invention uses non-halogen containing resin as a secondary insulating layer material, and has the outstanding flame retardance even if it does not add a flame retardant in particular. The high heat-resistant and high oil-resistant wire of the present invention has a high continuous use temperature, excellent in extrudability and oil resistance, and can keep the thickness of the secondary insulating layer thin.

The high heat and high oil resistance wire of the present invention is characterized by stable polymer properties after extrusion by applying a polymer material having high heat resistance and mechanical strength to a secondary insulating layer, and eliminating the need for a crosslinking process. Because of this feature, it is possible to manufacture a wire having a thin insulating layer while satisfying the requirements of the aviation and marine wires. The smaller size, volume, and weight reduce the risk of fire due to the reduction of combustion materials and make installation easier during manufacture or repair.

In the electric wire of the present invention, the primary insulating layer uses a polyolefin material. As the polyolefin constituting the primary insulating layer, widely used crosslinked polyethylene or ethylene-vinyl acetate (EVA) resin may be used, and another resin copolymerized with a polar ethylene monomer having a carboxyl group may be used.

 As the material for the secondary insulating layer, which is the core of the electric wire of the present invention, a polymer resin having a high glass transition temperature and a continuous use temperature, having a high flame retardancy and an excellent extrudability, is properly selected to achieve the object of the present invention. As the secondary insulating layer material of the electric wire of the present invention, polyether ether ketone, polyimide, or polyphenylene sulfide is suitable.

Polyether ether ketone (PEEK) is an aromatic thermoplastic resin, not only excellent in processability, but also the heat resistance and chemical resistance of the thermosetting resin is added, the performance of the thermoplastic resin currently in use is the best. PEEK has a glass transition temperature of 143 ° C and melting point of 343 ° C due to the rigid structure of the aromatic ring. In addition, it has excellent impact resistance or abrasion resistance, and has a chemical resistance that does not invade drugs other than concentrated sulfuric acid or concentrated nitric acid. It shows higher flame retardancy than existing fluorine resin, and satisfies UL 94V-0 flame retardant without adding flame retardant. It does not contain halogens, and due to its chemical structure and purity, there are few emissions of smoke and toxic substances.

It is preferable that the number average molecular weight range of the said PEEK resin is 7 * ¹⁰ <^4> -11 * ¹⁰ <^4> . If the number average molecular weight is less than 7ⅹ10 ⁴ , it is difficult to control the extrusion thickness, and the strength of the insulator is weak so that defects are likely to occur. On the other hand, the resin of 11ⅹ10 ⁴ or more has a low melt viscosity and poor flowability, so that a lot of loads are extruded, so that continuous work is difficult and thin thickness is difficult to complete. In addition, due to the high crystallization rate, rapid molecular orientation near the freezing point is formed as it is during extrusion, making it difficult to form a uniform appearance.

Among the polyether ether ketone resins for secondary insulating layers of the present invention, poly (oxy-1,4-phenylene-oxy-1,4-phenylene-carbonyl-1,4-phenylene) is most preferred. The structure of this polymer is shown in Formula 1 below.

Polyimide-based polymer can be used for the secondary insulating layer resin of the electric wire of the present invention. Among the polyimide-based polymers, resins represented by the following general formula (2) are preferable. This resin is a thermoplastic polyimide molecule known as Ultem (trade name of GE), which is a polyetherimide having introduced ether linkages for further molding processability. Ultem has a moderate heat resistance between polyester and polyimide and the continuous use temperature is above 170 ° C. Used alone or in place of a double coating of polyester, or coated or extruded on polyester, it shows excellent stability. In order to be used as the material of the secondary insulating layer for electric wires of the present invention, the melt index is at least 0.9 g / min (based on ASTM D 1238) for the extrusion application, and the oxygen index is 40 in order to have flame retardancy even in the natural state without the additive. The above materials are preferable. It is not suitable to mix glass fiber with Ultem for oil resistance and flexibility of insulated wire.

Extem (trade name of GE Plastics), which is basically the same chemical structure as Ultem, is also a thermoplastic polyimide. It is an excellent feature that has both low thermal expansion coefficient of amorphous resin and chemical resistance of crystalline resin. Extems have a higher heat resistance temperature of about 100 ° C. and superior dimensional stability and flame retardancy due to temperature change compared to Ultem because of differences in manufacturing processes. The glass transition temperature is up to 311 ° C and the continuous use temperature is 250 ° C or higher. The xtem to be applied as the secondary insulating layer of the present invention is preferably a polymer having a glass transition temperature of 280 ° C or higher and a heat deformation temperature of 240 ° C or higher. The extem resin used in the secondary insulating layer of the present invention preferably has a melt index of at least 1 g / min or more and a transparent index to distinguish the color from the primary insulating layer.

Polyphenylenesulfide (polyphenylenesulfide) is superior to the major engineering plastics, such as thermal properties, mechanical properties, chemical resistance, dimensional stability is very excellent. The glass transition temperature is 85 ℃ ~ 93 ℃, the melting point is 277 ℃ ~ 285 ℃, the continuous use temperature is 220 ℃ ~ 240 ℃, and the heat deformation temperature is over 260 ℃, and it has high heat resistance. Preferably, the poly sulfide phenylene sulfide for the secondary insulating layer of the present invention has the structure of Formula 3 below.

Examples of the polysulfide phenylene resin include a polymer of crosslinked molecular structure and a polymer of linear molecular structure. The crosslinking type introduces the cyclic oligomer produced during the reaction into the polymer in the thermal crosslinking process. The straight chain is polysulfide phenylene which has been high molecular weight in the reaction step using a polymerization aid. Resin which can be used preferably in this invention is linear. It is preferable to use polysulfide phenylene whose initial loss modulus is at least two times the storage modulus for extrudability. The polyphenylene sulfide mainly made of linear type can be processed by continuous extrusion molding and has sufficient flexibility as a coating layer of multilayer insulated wire. Herein, the main form of the straight chain means that approximately 75% or more of the total constituent components of the polysulfide phenylene resin is composed of the straight chain polysulfide phenylene resin component. In order to ensure flexibility, the elongation at break is satisfied at least 50% (according to IEC 60811-1-1, speed 250 mm / min).

The present invention will be described in more detail with reference to the following Examples. The average person skilled in the art to which the present invention pertains may change the present invention in various other forms in addition to the embodiments described in the following examples, and the following examples merely illustrate the present invention, and the scope of the technical spirit of the present invention is given below. It is not to be construed as limiting the scope of the examples.

In order to compare and evaluate the performance of the electric wire of the present invention having the secondary insulating layer made of the above-described polymer material and the electric wire of the prior art, the wire specimen of the embodiment according to the present invention and the comparative example of the prior art were manufactured with the structure as shown in FIG. It was. The conductor inside the wire specimen is 20 AWG (American wire gauge) tin-plated copper, and the primary insulation layer is made of crosslinked polyethylene (HDPE), a kind of irradiated crosslinked polyolefin (XLPO), and the thickness is 0.1 mm. It was set as. As the material of the secondary insulating layer, in Examples 1 to 4, poly (oxy-1,4-phenylene-oxy-1,4-phenylene-carbonyl-1,4-phenylene) resin, extem, ultem or PPS resin was used, and in Comparative Examples 1 and 2, crosslinked PVDF resin or crosslinked ethylene resin was used, respectively. The crosslinked ethylene resin of Comparative Example 2 is 50 parts by weight of HDPE 8380 (glass transition temperature 132 ℃, melt index 0.7 g / min, volume resistivity> 10 ⁵ Ω), ethylene-vinyl acetate 460 (15% by weight of vinyl acetate, melting) Index 2.5 g / min) and 50 parts by weight of vinylsilane surface treated magnesium hydroxide flame retardant. The thickness of the secondary insulation layer was 0.1 mm, similar to the thickness of the primary insulation layer.

 The insulated wire specimens prepared as described above were evaluated by performing physical property evaluation tests according to the criteria set forth in Part 18 of the Defense Standard 61-12 for each item described below. However, the high temperature load resistance test was evaluated by itself without conforming to the British Ministry of Defense standards. The measurement results are summarized in Table 1.

Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Constituent polymer PEEK Extem Ultem Polyphenyl Sulfide Crosslinking PVDF Crosslinked polyethylene High Temperature Load Resistance (Heat Strain) 40% 40% 50% 60% > 100% > 100% Home radio waves pass pass pass pass pass fail Oil resistance pass pass pass pass 10 kinds fail 13 kinds fail Flame retardant pass pass pass pass fail fail Shrinkage 0.5 mm 1 mm 1 mm 1 mm 2 mm 5 mm Low temperature bendability pass pass pass pass pass fail

1) High temperature load resistance test

The resistance force when the wire was loaded under high temperature conditions was measured. A blade jig of 1200 g load was applied to the wire specimen at 12O &lt; 0 &gt; C for 12 seconds and then the heat strain (%) was measured. Here, the heat strain is calculated by measuring the initial thickness of the insulator and the thickness of the insulator after 12 seconds at 120 ° C. On the other hand, check whether the blade jig touches the conductor inside the wire. The lower the% heating strain, the better the material.

 2) Notch propagation

Both ends of the 500 mm cable were stripped about 25 mm and notched to the center with a length of 30% of the minimum radius. An immersion test is carried out with a 2.5 kV voltage wound around the vane with a diameter of three times the outside of the cable.

3) oil resistance

 About 20 kinds of oil and solvents defined in the above specification (see Table 2 below) are cured for one week at each designated temperature, and then the appearance of cracks and delamination of the coating layer is observed and a 2.5 kV voltage is applied. Immersion experiment is performed. Excellent material should be free from cracking and peeling.

Type of fluid Temperature (℃)  fuel Aviation turbine oil 70 ± 2 70 ± 2 Kerosene 70 ± 2 gasoline 40 ± 2   Hydraulic fluid Mineral oil 50 ± 2 70 ± 2 Phosphate Ester Base 100 ± 2 70 ± 5 Silicon based 150 ± 5 70 ± 2 Non-mineral oil base 100 ± 2 Silicate ester base (synthetic) 100 ± 5 lubricant Mineral oil 100 ± 5 Ester Base (Synthetic) 150 ± 5 Solvent and wash solution Propan-2-ol (isopropyl alcohol) 50 ± 2 PH 10 detergent cleaning solution 20 ± 2 Deicing agent, antifreeze Kilfrost ABC 50 ± 2 Sullage Formaldehyde 4 ± 0.1%, cresylic acid 1 ± 0.1% and water 95% (isomer mixture, general purpose reagent)  23 ± 2 Brine 50 ± 2 Deionized water 50 ± 2

4) Flame retardant

 The flame is tilted at 60 degrees to a 900 mm long specimen for 12 seconds and observed to be carbonized below 75 mm. The shorter the carbonization length, the better the material.

5) Shrinkage

Cure 4 hours at 120 ℃ and leave for 1 hour at room temperature. Perform three times to observe whether the coating layer should not peel off and exceed the shrinking length. The contraction length is less than 3 mm to meet the criteria.

6) Cold bend

Wind the wire with a force of 100 N in a vane with a wire diameter of 20 times and leave it for 6 hours at -50 ° C ± 2 ° C. Then, immersion test is performed under the applied voltage of 2.5 kV.

When looking at the data of Table 1, it can be seen that the wire specimens of Examples 1 to 4 significantly improved high temperature load resistance and oil resistance, which are important characteristics in ship and aviation industries, compared to Comparative Examples 1 and 2.

In the case of high temperature internal load resistance, in Comparative Example 1 and Comparative Example 2, the thermal strain exceeded 100%, and the mechanical properties rapidly deteriorated at a high temperature. In Comparative Example 2, the insulating layer was completely deformed by the blade jig in about 5 seconds, and in Comparative Example 1, the insulator was severely deformed to reveal the conductor. However, Examples 1 to 4 showed less than half the heat strain of the comparative example and showed excellent durability.

In the case of oil resistance, in Comparative Example 1, cracks and peeling of the coating layer were observed in the aviation oil and metacresol oil resistance test, and in Comparative Example 2, cracks or insulation layers were generated for almost all oils and solvents such as aviation oil, lubricating oil, and solvent. Or 2.5 kV withstand voltage. The wire specimens of the examples showed excellent oil resistance for all 20 species.

Examples 1 to 4 did not add any flame retardant, but all of the flame retardancy criteria were satisfied. However, Comparative Examples 1 and 2 of the prior art failed. In Comparative Example 2, although the flame retardant having the same weight as the resin was put in, the flame retardancy was failed. In particular, in Comparative Example 1, 150 mm of the wire was burned, and thus the flame retardancy was very insufficient.

In the case of low-temperature foldability, Comparative Example 2 did not meet the criteria, unlike the examples all showed good results. Although the secondary insulation layer of the comparative example 2 is a crosslinked ethylene resin with cold resistance, the low foldability is judged to be the result of the addition of a flame retardant and other additives to lowering the cold resistance of the material itself.

As can be seen from the above comparative evaluation results, since the wire or cable of the present invention adopts a material having high glass transition temperature and continuous use temperature and has excellent extrudability as the secondary insulating layer, excellent physical properties can be maintained at high temperature and Make the thickness of as thin as possible.

The terminology used in the description and examples herein is for the purpose of describing the invention in detail to those skilled in the art, and is intended to limit the scope of the invention in any particular sense or in the claims. It was not intended.

The following drawings attached to this specification are illustrative of preferred embodiments of the present invention, and together with the detailed description of the invention to serve to further understand the technical spirit of the present invention, the present invention is a matter described in such drawings It should not be construed as limited to.

1 is a cross-sectional view schematically showing the structure of an electric wire having a double insulation layer.

Claims (8)

In a wire comprising a conductor, a primary insulating layer containing the conductor and a secondary insulating layer containing the primary insulating layer, The primary insulating layer is made of a polyolefin resin, The secondary insulation layer is selected from the group consisting of polyether ether ketone, polyimide, and polyphenylene sulfide. The method of claim 1, The polyether ether ketone has a number average molecular weight of 70,000 to 110,000, characterized in that a high heat resistance and high oil resistance electric wire. The method of claim 2, The polyether ether ketone is a poly (oxy-1,4-phenylene-oxy-1,4-phenylene-carbonyl-1,4-phenylene) high heat resistance and high oil resistance electric wire. The method of claim 1, The polyimide has a high heat resistance, high oil resistance electric wire having a repeating unit of the formula (2). [Formula 2]

The method of claim 4, wherein The polyimide has a melt index of at least 0.9 g / min, A high heat resistant and high oil resistant wire, characterized by having an oxygen index of 40 or more in the absence of an additive. The method of claim 4, wherein The polyimide, A high heat and high oil resistance wire, wherein the glass transition temperature is at least 280 ° C, the heat distortion temperature is at least 240 ° C, and the melt index is at least 1 g / min. The method of claim 1, The polyphenylene sulfide has a high heat resistance and high oil resistance electric wire having a repeating unit represented by the following general formula (3). [Formula 3]

The method of claim 7, wherein The polyphenylene sulfide is a high heat-resistant, high oil-resistant electrical wire, characterized in that the initial loss modulus is a linear resin of more than twice the storage modulus.

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