JPS6349323B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to shaped articles of cross-linked fluorinated carbon polymers, and more particularly to electrically insulated metal wires having such shaped articles as electrically insulating coatings on the metal wires, and to methods of making the same. It is known to make shaped articles of cross-linked polymers by shaping non-cross-linked polymers and exposing the shaped articles to ionizing radiation. However, when this method is applied to fluorinated carbon polymers, the polymers not only cross-link, but also undergo irradiation-induced degradation, and the final products have poor physical properties. Although this drawback can be alleviated by mixing a cross-linking agent (this is known as a co-agent) with the fluorinated carbon polymer before molding, the physical properties of the known products are still quite satisfactory. 200°C or higher, which is often desired or required, especially when melt-forming fluorinated carbon polymers.
Particularly in the case of molding processes involving temperatures above 250°C, this is not entirely sufficient. In particular, the known processes do not provide products with a combination of high tensile strength at room temperature and the high degree of crosslinking necessary to obtain good physical properties at temperatures above the melting point of the polymer. The present invention overcomes the shortcomings of the prior art and provides molded articles of fluorinated carbon polymers that have a high degree of crosslinking while maintaining high tensile strength. The M ₁₀₀ value, which is the static modulus above the melting point of the polymer and is measured by the method described below, is a measure of the degree of cross-linking. It has been found in accordance with the present invention that such molded articles exhibit significant physical properties and that these properties are particularly useful when the molded article is in the form of an insulating coating on a wire. That is, the present invention provides an electrically insulated metal wire having an electrically insulating melt-formed coating of a cross-linked ethylene/tetrafluoroethylene copolymer, wherein the copolymer contains 35 to 60 mole percent ethylene; ~
60 mol % of tetrafluoroethylene and 0 to 10 mol % of one or more other comonomers, and the coating has a thickness of up to 0.04 cm and a coating of at least 31.5 Kg/cm ² . M ₁₀₀ value and at least 350Kg/
^cm2 tensile strength and elongation rate of 40% or more,
or the coating has a thickness greater than 0.04 cm, and has an M ₁₀₀ value of at least 28 Kg/cm ² , a tensile strength of at least 420 Kg/cm ² and an elongation of 40% or more. , providing the electrically insulated metal wire. The invention also includes a first method for manufacturing a wire with such a shaped coating. This process comprises: (i) (a) ethylene/tetrafluoroethylene consisting of 35-60 mol% ethylene, 35-60 mol% tetrafluoroethylene and 0-10 mol% of one or more other comonomers; A melt-formed coating of fluoroethylene copolymer provided that the coating has a tensile strength greater than 350 Kg/cm ² for thicknesses up to 0.04 cm;
(b) a liquid composition comprising a cross-linking agent, the coating having a tensile strength of at least 2.5 kg/ ^cm2 ; % by weight of cross-linking agent; and (ii) exposing the coating to ionizing radiation until the coating contains 0.04
At least 350Kg/cm ² for thickness up to cm
at least 31.5Kg/ while maintaining tensile strength of
Sufficiently cross-linked to impart an M ₁₀₀ value of cm ² and, for thicknesses greater than 0.04 cm, an M ₁₀₀ value of at least 28 Kg/cm ² while maintaining a tensile strength of at least 420 Kg/cm ² and
It is characterized by irradiation with a dose not exceeding 50 megarads under conditions such that the cross-linked coating has an elongation rate of 40% or more. The invention further includes a second method for manufacturing a wire with a shaped coating according to the invention,
The method comprises: (A) contacting a metal wire with a shaped coating as described above with a flowable composition containing a cross-linking agent until the shaped coating absorbs at least 0.5% by weight of the cross-linking agent; B) irradiating a molded coating containing at least 0.5% by weight, preferably at least 2% by weight and especially at least 4% by weight of absorbed crosslinker at the start of irradiation to a dose not exceeding 50 megarads,
a tensile strength of at least 5000 psi (350 Kg/cm ² ) at °C for coatings up to 0.04 cm thick;
For thicknesses greater than 0.04 cm, cross-linking is performed while maintaining a tensile strength of at least 6000 psi (420 Kg/cm ² ). For thicknesses up to cm at least
repeating successively until it has an M ₁₀₀ value of 31.5 Kg/cm ² and, for thicknesses greater than 0.04 cm, an M ₁₀₀ value of at least 28 Kg/cm ² . Steps (A) and (B) of this method are the same as the first method described above.
It is recognized that steps (1) and (2) are similar (and may be identical), but since steps (A) and (B) are repeated at least once, the crossover that exists at the beginning of step (B) A minimum amount of binder (2) less than the minimum amount at the beginning of the process and only after the final irradiation step an M ₁₀₀ value of at least 31.5 Kg/cm ² or 28 Kg/cm ² is required. By using this sequential method,
Significantly high M ₁₀₀ value, e.g. 1000psi (70Kg/cm ² )
or more, such as 2500psi (175Kg/cm ² )
It has been found that it is possible to obtain a wire with a molded coating with a higher M ₁₀₀ value. The cross-linking agent-containing flowable composition used in the repetition of step (A) is usually the same in each step (A), but may be different. Similarly, the conditions used in the repetition of step (B) may be the same or different for each step (B). As used herein, the term "fluorinated carbon polymer" refers to a polymer or polymer mixture containing 10% by weight or more, preferably 25% by weight or more of fluorine. Therefore, the fluorinated carbon polymer may be a single fluorine-containing polymer, a mixture of two or more fluorine-containing polymers, or a combination of one or more fluorine-containing polymers and one fluorine-containing polymer. Or it may be a mixture with a polymer containing no more fluorine. Preferred fluorinated carbon polymers are those containing at least 50%, especially at least 75%, more particularly at least 85% by weight of one or more thermoplastic crystalline polymers each containing at least 25% by weight of fluorine. and a single type of such crystalline polymer is preferred. Such fluorinated carbon polymers may contain, in addition to one or more crystalline fluorine-containing polymers, a fluorine-containing elastomer and/or a polyolefin, preferably a crystalline polyolefin. Fluorine-containing polymers are generally 1
Homo- or co-polymers of one or more fluorine-containing olefinically unsaturated monomers, or copolymers of one or more such monomers with one or more olefins. It is a combination. the fluorinated carbon polymer has a melting point of at least 200°C;
It will often have a melting point of at least 250°C, for example up to 300°C. This melting point is defined for crystalline polymers as the temperature above which no crystals are present in the polymer (or in the main crystalline component of the mixture when a mixture of crystalline polymers is used). Suitable polymer compositions have a viscosity of less than 10 ⁵ poise at a temperature not more than 60° C. above their melting point. Fluorinated carbon polymers suitable for the present invention are copolymers of ethylene and tetrafluoroethylene and optionally one or more other copolymers (known as ETFE polymers);
In particular, the copolymer consists of 35 to 60 mole % ethylene, 35 to 60 mole % tetrafluoroethylene and up to 10 mole % of one or more other coweights. The polymer composition optionally contains antioxidants,
Suitable additives such as heat stabilizers, acid acceptors and processing aids may be included. Fluorinated carbon polymers, especially ETFE polymers, are self-extinguishing.
Although it is recognized in the art that the cross-linking according to the present invention significantly increases their flammability, as measured by the test method described below, a suitable amount (preferably
It has been found that this increase can be virtually eliminated by including 0.5 to 6% by weight of antimony oxide. The polymer composition may also contain a crosslinker added to the polymer according to known methods before shaping. However, it is preferable to avoid this case. This is because the presence of a crosslinker limits the conditions that can be used during the molding process and tends to result in an extrudate that in any case has non-uniform properties along its length. Furthermore, more effective utilization of the crosslinker is achieved when it is absorbed into the molded article according to the present invention and is therefore independent of the conditions of the molding process. It is also possible that the initial composition is already cross-linked, but in this case further cross-linking is necessary to make the shaped article suitable for its intended use. The shaped article of the polymer composition can be in any form. That is, it can be in the form of a sheet, tube or gasket, but it can also be in the form of a coating on a substrate, especially an elongated substrate, and more particularly, in the present invention, on a metal (e.g. copper) wire or other electrical wire.
Alternatively, it is preferably in the form of an insulating coating on a plurality of parallel spaced conductive wires. The coating can be comprised of a first inner layer of a fluorinated carbon polymer composition and a second outer layer of a second fluorinated carbon polymer composition, such that the first and second The compositions may be the same or different. These layers may be in direct contact or may be fused together;
Alternatively, they may be slightly movable relative to each other, or may be bonded to each other by a layer of adhesive. The shaped article can be formed by melt-molding the polymer composition, e.g. by extrusion (which is preferred),
Preferably, it is formed by injection molding or transfer molding. The temperature at which the composition is melt-molded is of course above the melting point of the polymer, ie above 200°C, often above 250°C. A particularly preferred method is to melt extrude the composition as a coating around an elongated substrate. High tensile strength is generally desired in cross-linked products and
Because fluorine-containing polymers other than ETFE polymers often lose tensile strength during the irradiation process,
It is also necessary to have a higher initial tensile strength (see Examples 14 to 21 below). When using crystalline fluorinated carbon polymers, especially when the ETFE polymer is formed by melt-extrusion into relatively thin coatings, such as coatings up to 0.015 inch (0.04 cm) thick around the wire. , this initial tensile strength is often at least 6000psi (420Kg/
cm ² ), preferably at least 7000 psi (490 Kg/cm ² ),
In particular it will be at least 7500 psi (525 Kg/cm ² ), more particularly at least 8000 psi (560 Kg/cm ² ).
Such an initial tensile strength can be easily obtained by a known molding method. Suitable crosslinkers contain carbon-carbon unsaturated groups in a mole percent of 15 or more, especially 20 or more, more especially 25 or more. In many cases, the crosslinking agent contains at least two ethylenic double bonds, such as allyl, metaallyl, propargyl or vinyl groups, which may be present. Excellent results have been obtained with the use of crosslinkers containing at least 2 allyl groups, especially 3 or 4 allyl groups.
Particularly preferred cross-linkers are triallyl cyanurate (TAC) and triallyl isocyanurate (TAIC); other specific cross-linkers include triallyl trimellitate, triallyl trimesate, tetraallyl pyromellitate. Tate, 4,
Includes diallyl ester of 4'-dicarboxydiphenyl ether and diallyl ester of 1,1,3-trimethyl-5-carboxy-3-( p -carboxyphenyl)indane. Other crosslinking agents known for incorporation into fluorinated carbon polymers prior to molding, such as those described in U.S. Pat.
No. 3763222; No. 3840619; No. 3894118; No. 3911192; No. 3970770; No. 3985716;
Those described in 3995091 and 4031167 can also be used. Crosslinker mixtures can also be used. The flowable composition containing the cross-linking agent is preferably a liquid composition; that is, the composition consists essentially of the cross-linking agent having a suitable melting point;
Alternatively, it can be a solution of the agent in an organic solvent, preferably the solvent is a swelling agent for the polymer. Suitable solvents include chloroform, chlorobenzene, dioxane, trichlorobenzene and some other halogenated or ethereal solvents such as tetrahydrofuran and dimethyl ether of diethylene glycol. The liquid composition preferably contains a polymerization inhibitor. The cross-linking agent can also be in vapor form at atmospheric or superatmospheric pressure. at least one of the contacts of the molded coating and the cross-linking agent;
The reaction is often carried out at an elevated temperature below the melting point of the polymer, preferably at least 25°C below the melting point of the polymer, for example at a temperature of 180-225°C, such as at least 150°C, preferably 180-210°C. is advantageous because this temperature increases the rate at which the crosslinker diffuses into the polymer composition. If the molded coating is formed by melt-extrusion, the extruded coating can be cooled in a liquid composition containing a cross-linking agent. Of course, the concentration of crosslinker in the molded coating at any particular point will depend on the distance between this point and the surface of the molded coating that comes into contact with the flowable composition containing the crosslinker. (Except in limited theoretical cases where contact continues for a length that equilibrium is achieved). (For the avoidance of doubt, it must be pointed out that the concentrations of crosslinkers given herein are average concentrations). Similarly,
It is believed that the crosslink density of a crosslinked molded coating decreases from the surface of the molded coating inward, and that this may have a beneficial effect on the physical properties of the molded coating. It is preferred that the molded coating should be relatively thin to ensure adequate penetration of the crosslinking agent into the molded coating without using excessive contact time. That is, the coating is preferably less than 0.05 inches (0.125 cm) thick;
Especially with a thickness of less than 0.02 inches (0.05 cm). Slow loss of crosslinker from the molded coating over a period of one or more days at room temperature after the molded coating is removed from contact with the flowable composition, such as a loss of 1 or 2% based on the weight of the coating. is often seen. Therefore, it is preferred that irradiation should be carried out within a few hours at the most after the contacting step is completed. At the start of step (2) of the first method, the molded coating should contain at least 2.5% by weight, preferably at least 4% and especially at least 5% by weight of crosslinker. Amounts as low as 0.5%, e.g. at least 2%, have an acceptable effect on cross-linking by subsequent irradiations and can therefore be used in the second method of repeated contact and irradiation, but experimentally According to the authors, when the cross-linking is carried out in a single step, an amount of at least 2.5%, e.g. Quantity is required. An amount greater than 20%, especially an amount greater than 30% (1)
In rare cases, results will adequately compensate for the additional time required in the process. The irradiation dose used in the irradiation process is 50% to ensure that the polymer does not deteriorate due to excessive irradiation.
The preferred radiation dose used will of course depend on the desired degree of cross-linking balanced against the tendency of the polymer to be degraded by high radiation doses. . Suitable radiation doses generally range from 2 to 40 Megarads, such as from 2 to 30 Megarads, preferably from 3 to 20 Megarads, especially from 5 to 25 or 5 to 20 Megarads, more particularly from 5 to 15 Megarads. This ionizing radiation can be in the form of accelerated electrons or gamma rays, for example. Irradiation is generally carried out at about room temperature, although higher temperatures can also be used. The cross-linked molded coating according to the invention has a high
It has both M ₁₀₀ value and high tensile strength. Substantially higher M ₁₀₀ value and tensile strength are preferred;
These are readily obtainable in the present invention, particularly in the case of melt-extruded coatings as relatively thin materials under conditions in which the polymer is rendered oriented. Therefore, the M ₁₀₀ number is preferably at least 450 psi (31.5 Kg/cm ² ), especially at least 600 psi (42 Kg/cm ² ), even more especially at least 750 psi (52.5 Kg/cm ² ); and the tensile strength is preferably at least 5000 psi (350 Kg/cm ² ), more preferably at least 6000 psi (420 Kg/cm ² );
Particularly at least 7500 psi (525 Kg/cm ² ), most preferably at least 8000 psi (560 Kg/cm ² ). When the shaped article is in the form of an electrically insulating coating on metal wire, and the coating has a thickness of up to 0.015 inches (0.04 cm), its M ₁₀₀ value will generally be at least 450 psi (31.5 Kg/cm ² ). ; preferably at least 500 psi (35 Kg/cm ² ), especially at least 650 psi (45.5
Kg/cm ² ), more particularly at least 750 psi (52.5 Kg/cm 2 )
cm ² ) and its tensile strength is generally at least 5000 psi (350 Kg/cm ² ), preferably at least
6000psi (420Kg/cm ² ), especially at least 7000psi
(490Kg/cm ² ), more particularly 7500psi (525Kg/cm ² ),
Most preferably at least 8000 psi (560 Kg/cm ² ). M ₁₀₀ if the shaped article is in the form of an electrically insulating coating on a metal wire and the coating has a thickness of at least 0.015 inches (0.04 cm).
The tensile strength is preferably at least 400 psi (28 Kg/cm ² ) and the tensile strength is preferably at least 6000 psi (420 Kg/cm ² ). If the shaped article is in the form of an insulating coating on a wire, the coated wire is a crossed wire.
It has been found that it exhibits significantly high values for abrasion resistance (the most important property for wires used in aircraft), scrape abrasion resistance and hot cut-through resistance. For example, insulated wires having a wire cross-wear resistance (measured as described below) of at least 2 x 10 ⁴ cycles and often at least 2 x 10 ⁵ cycles at 1 Kg load can be readily obtained in accordance with the present invention. Furthermore, according to the present invention, the insulated wire of the present invention has a very low temperature of 7.
lb (3.2Kg) or more, especially _M100 value of at least 750psi (52.5Kg).
Kg/cm ² ) was found to have a cut resistance of greater than 7 pounds (3.2 Kg). The crosslinked molded article should have an elongation of 5% or more, preferably 10% or more for most applications, especially if it is in the form of a coating on a wire. It is preferably 40% or more, particularly 50% or more. If the shaped article is in the form of a double layer coating as described above, contact with the crosslinking agent can be carried out both before and after application of the outer layer using the same or a different crosslinking agent. or it can be done only after applying the outer layer. This contact is carried out under conditions such that the cross-linking agent is dispersed throughout both layers and cross-links both layers upon irradiation. Various physical properties cited herein are measured as set forth below. M ₁₀₀ Valence The M ₁₀₀ valency quoted herein refers to the static temperature measured at a temperature approximately 40°C above the melting point of the cross-linked polymer (e.g., approximately 320°C for the ETFE polymer used in the example below). Determined by force coefficient. This test measures the stress required to stretch a sample of cross-linked molded articles to 100% (or to rupture if 100% stretch cannot be achieved). This specimen [e.g., a 4 inch (10 cm) length of insulation separated from the wire, or 1/8 x 0.02 x 4 inch (0.32 x 0.05 x 10 cm) cut from a flat plate.
1 inch (2.54
cm) apart and then place the sample in an oven maintained at the test temperature.
Attach a g weight and hang it vertically. After 2 minutes of equilibration, the weight attached to the bottom of the sample is increased until the distance between the marks increases to 100% or the sample ruptures. Then, from the following equation
Calculate the M ₁₀₀ value: M ₁₀₀ = Stress × 100 ÷ Elongation rate / Initial cross-sectional area Tensile strength and elongation rate The tensile strength and elongation rate used in this specification are
50mm according to ASTM D638−72 (i.e. 23℃)
Measurements are made at a test speed of (2 inches)/minute. Wire cross abrasion resistance The wire cross abrasion resistance used in this specification is 2.
It is determined by a test that involves rubbing the crossed wires of a book against each other in a controlled manner with vibrations of 50 Hz, thereby creating a frictional phenomenon that can occur, for example, in high-vibration areas of an aircraft. The test device includes a small vibrator mounted tightly on a heavy steel frame, which causes an axial driver to reciprocate in a horizontal plane. The axial driver is connected via a horizontal spring steel rod to a rocker arm that generally has a horizontal upper surface on which a curved wire specimen holder is mounted. The center of this holder is perpendicular to the center of rotation of the rocker arm, and its bending is such that the top surface of the wire held there forms an arc of a cycle, the center of which is the center of rotation of the rocker arm. is the center of rotation. The radius of this cycle is 5.5 inches (14 cm). Therefore,
When the wire is placed horizontally, there is no substantial vertical movement of the wire. A second (upper) wire specimen is mounted on the underside of the beam, and one end of this wire is secured to the frame via a thin strip of damping alloy that acts as a hinge, so that the beam can only be displaced vertically. do. In the test position, the beam is placed on the beam and extends horizontally from the frame so that the wire compresses on the wire attached to the swing arm; the pressure force is generally attached to the frame and the beam is free provided by an upright rubber band covering one end. Position the beam and swing arm so that each wire makes a 30° angle with the axis of the shaft driver, and the internal angle between the crossed wires is 60°. When the lower sample is moved up and down, a friction pattern is created in which the symmetrical arrangement near the driver axis is essentially the same for both wires. Measure the number of cycles required to create electrical contact between each wire. The force between the wires is measured with a Hunter force gauge before and after each test by varying the threaded tension adjustment until the upper sample separates from the lower sample. A microscope is used to measure the separation point. Cut resistance Load the wire sample on an anvil. on the anvil
There is a wedge-shaped loaded Nahui blade with a 90° internal angle. The blade of this blade has a flat thickness of 0.005 inch (0.0125 cm) and a flat thickness of 0.005 inch (0.0125 cm)
It has a radius edge of The anvil is suspended in stirrups from the load chamber of the Instron Tensile tester, and the knife blade is suspended above the movable bar of the tensile tester so that the blade blade traverses the wire specimen. Set it up like this. The blade of this knife is 0.2 inch (0.51
cm)/min toward the wire. Breakage occurs when the knife blade comes into contact with the conductor. The electrical contact that occurs causes the tension tester to stop advancing the blade. The apex reading from the load chamber is read as the cut resistance of the wire. Friction and Wear Resistance The wire is tightly attached in a jig under tension along its length, and the knife edge is at an internal angle of 90°.
A wedge-shaped loaded knife blade having a radius of 0.005 inches (0.0125 cm) is then placed in a cross shape with the wire so that the knife blade is on the wire. The blade of this knife is loaded with the weight of each species [3 pounds (1.36 kg) in total in the example below],
Blade support on the wire can be increased. To test the frictional wear resistance of the wire under test, the blade is reciprocated in 2 inch (5.1 cm) strokes along the length of the wire at a frequency of 120 strokes (or 60 cycles)/minute. Breakage occurs when the knife blade makes contact with the conductor, which breaks the electrical circuit. Flammability The flammability test is performed in a sheet metal cabinet according to FED-STD-191, Method 5903 as follows: Strip 2 inches (5.1 cm) of insulation from one end of an 18-inch sample and place the sample in a Bunsen tube. The burner is placed under tension in the vertical direction with a bare conductor placed at an angle from the vertical so that the burner can be placed directly below the test sample. A 1.5 inch (3.8 cm) high yellow flame from a Bunsen burner is applied to the sample at the point of contact between the insulation and the bare conductor, such that the bottom edge of the insulation is 0.75 inch into the flame. After 12 seconds of applying the flame, remove the burner from under the sample.
Extinguish the fire immediately. Record the burn length and burn time after removing the flame. Burn length is the distance from the original knot made in the conductor to the furthest point of damage. Damage is indicated by exposed conductors or scorched insulation due to burning insulation. The invention will be illustrated by the following examples and comparative examples. These examples are summarized in the table below, in which the percentages are by weight. The various symbols shown in the table have the following meanings; the symbol (C) after the example number indicates that this example is a comparative example. [C ^*
Example 10 marked with is itself a comparative example, but
It is also a comparative example with the same type of Example 11 (as well as Examples 12 and 13) which is not included in the present invention because it is compression molded]. Polymer Polymer A contains 0.2% TiO ₂ and FTFE polymer [E. Ai. Dupont des Nemoers (EI)
Tefzel 280, sold by Dupont de Nemours and Co., is approximately 46% ethylene and 50% tetrafluoroethylene.
% and is believed to contain approximately 4% fluorinated alcohol]. Polymer B is the ETFE polymer in Polymer A that does not contain _TiO2 . Polymer C is 0.2% TiO ₂ , 4% antimony trioxide and Polymer A is 95.8% ETFE polymer.
It is a mixture of The designations "from 10", "from 11" and "from 12" in Examples 11, 12 and 13 respectively mean that the cross-linked product from this previous example was used as starting material. Polymer D is a polymer of ethylene and chlorotrifluoroethylene (1:1 mole), which is not included in the present invention [“Halar” sold by Allied Chemical Co. 300].
Polymer E is an ETFE polymer [A. Ai. "Tefzel" 200, sold by DuPont,
This appears to be the same as the ETFE polymer in Polymer A, except that it contains a small proportion of fluorinated alkenol]. Crosslinker TAIC is triallylisocyanurate. TAC is triallyl cyanurate. TATM is triallyl trimesate. TAPM is tetraallyl pyromellitate. In Examples 1-9, the polymer compositions are melt-extruded onto tinned copper wire (20 AWG, 0.095 cm diameter) to form a coating approximately 0.01 inch (0.025 cm) thick thereon. In Examples 10-13, the polymer compositions are compression molded into approximately 0.01 inch (0.025 cm) thick plates at a molding temperature of 320°C. example
14-29, the polymer composition is melt-extruded into a 0.01 inch (0.025 cm) thick tape. The shaped article is immersed in a bath of the indicated crosslinking agent for the indicated time. The sample is then removed from the bath, excess crosslinker is wiped off, and the sample is irradiated with the indicated dose. After annealing at 150℃ and then cooling,
Measurements are made to determine the tensile strength M ₁₀₀ and the percentage weight gain due to absorption of crosslinker (percentages in Examples 11 to 13 are based on the weight of the plate used in Example 10). The molded articles were molded for 1 hour for Examples 1, 8 and 9, for 30 minutes for Examples 2-7, and for Examples 14-14.
Anneal at 150°C for 15 minutes in 19; Examples 10 to 13
The irradiated plates used in the following examples are not annealed, but the crosslinker percentage, tensile strength and M ₁₀₀ value are measured on plates annealed at 150° C. for 20 minutes. The insulated wire obtained in Example 1 had the following properties. Cut Resistance (a) 62 lbs (28 Kg) at 23°C (b) 7.8 lbs (3.5 Kg) at 150°C Friction Wear 86 cycles at 23°C Wire Cross Wear Resistance (a) 4.5 x 10 ⁵ cycles at 2 Kg ( b) 5.4×10 ⁵ cycles at 1.7Kg (c) 1.8×10 ⁶ cycles at 1.5Kg (d) 4.3×10 ⁶ cycles at 1.2Kg (e) >3×10 ⁷ cycles at 0.8Kg (f ) 0.7Kg for >3×10 ⁷ cycles The insulated wires obtained in Examples 2, 3, 4, 5, 6 and 7 were 5.1, 5.9, 6.2, 6.2 at 150°C, respectively.
Has cut resistance of 7.1 and 8.2 lbs (2.3, 2.7, 2.8, 2.8, 3.2 and 3.7Kg). The insulated wires obtained in Examples 8 and 9 gave the following results in the combustion test.

[Table] The insulation was burnt, but it did not fall off the wire. Examples 10 to 13 were not melt-molded, so the M ₁₀₀ value was low despite the high weight increase. Examples 14 to 21 are not ETFE polymers and therefore have large tensile strength losses due to irradiation. Examples 22-29 demonstrate the effect of crosslinker type and dose.

[Table] Note that the elongation rates in the tests of Examples 1, 4 to 7, 9, and 24 were 40% or more.

Claims (1)

[Scope of Claims] 1. An electrically insulated metal wire having an electrically insulating melt-formed coating of a cross-linked ethylene/tetrafluoroethylene copolymer, the copolymer containing 35 to 60 mole percent ethylene; The film is composed of 35 to 60 mol% of tetrafluoroethylene and 0 to 10 mol% of one or more other comonomers;
Have a thickness of up to 0.04cm and at least 31.5
has an M ₁₀₀ value of Kg/ ^cm2 , a tensile strength of at least 350Kg/ ^cm2 , an elongation of at least 40%, or the coating has a thickness of more than 0.04cm, and at least 28Kg/ ^cm2 M ₁₀₀ valence and at least 420Kg/
The electrically insulated metal wire is characterized by having a tensile strength of cm ² and an elongation of 40% or more. 2. The wire according to claim 1, wherein the coating has an elongation rate of 50% or more. 3. Wire according to claim 1 or 2, characterized in that the coating is an outer layer of polymeric insulation consisting of two layers. 4. Any of claims 1, 2, and 3, characterized in that the coating is cross-linked by irradiation in the presence of triallyl cyanurate or triallyl isocyanurate. or the wire according to item 1. 5 (i) (a) 35-60 mol% ethylene, 35-60 mol% tetrafluoroethylene, and 0-10 mol%
A melt-molded coating of an ethylene/tetrafluoroethylene copolymer consisting ^of one or more other comonomers of has
Also, if the thickness is greater than 0.04cm, 420Kg/
(b) a liquid composition comprising a cross-linking agent such that the coating contains at least ^2.5 % by weight of the cross-linking agent; contact up to;
and (ii) expose the coating to ionizing radiation such that the coating is 0.04
At least 350Kg/cm ² for thickness up to cm
at least 31.5Kg/ while maintaining tensile strength of
Sufficiently cross-linked to impart an M ₁₀₀ value of cm ² and, for thicknesses greater than 0.04 cm, an M ₁₀₀ value of at least 28 Kg/cm ² while maintaining a tensile strength of at least 420 Kg/cm ² and
Electrical insulation of cross-linked ethylene/tetrafluoroethylene copolymers characterized by irradiation with a dose not exceeding 50 megarads under conditions such that the cross-linked coating has an elongation of 40% or more electrically insulated metal wire with a melt-formed coating, the copolymer is
The coating is composed of 35 to 60 mol% ethylene, 35 to 60 mol% tetrafluoroethylene, and 0 to 10 mol% of one or more other comonomers, and the coating is 0.04 mol%.
with a thickness of up to cm and at least 31.5Kg/cm ²
has ^an M ₁₀₀ value of
A method for producing an electrically insulated metal wire having an M ₁₀₀ value of 28 Kg/cm ² , a tensile strength of at least 420 Kg/cm ² and an elongation of 40% or more. 6. The method according to claim 5, characterized in that the cross-linking agent is triallylcyanurate or triallyl isocyanurate. 7. Claims 5 or 6, characterized in that the liquid composition used in steps (i) and (b) is at a temperature from 150°C to 25°C below the melting point of the copolymer. The method described in section. 8. Process according to any one of claims 5 to 7, characterized in that the amount of crosslinker in the coating at the start of irradiation is at least 4%. 9. Process according to any one of claims 5 to 8, characterized in that the coating is irradiated with a dose of 5 to 15 megarads.