JPS6335680B2 - - Google Patents

Description

[Detailed description of the invention]

Highly polar compositions or materials have long been known to have a decisive and severe damaging effect on the electrical properties, such as insulation resistance and dielectric strength, of typical dielectric electrically insulating compositions or compounds thereof. It has been known for a long time. This significant damaging effect on electrical properties has led to the addition or use of many conventional additives or agents, such as flame retardants with highly polar characteristics, in many types of dielectric electrically insulating materials. Significant or absolute obstacles had arisen. Therefore, for these reasons, many highly effective commercially available flame retardants cannot be used in dielectric electrically insulating materials or products thereof, or the amounts or proportions of these highly polar flame retardant additives may not be suitable for the desired properties. The potential effectiveness of such flame retardants is reduced and electrically insulating materials and products using such additives are subject to limitations that compromise and complement other properties. The level of resistance to flame or combustion that would otherwise be obtained would be markedly reduced. The present invention involves treating polar additives for use in electrically insulating polymeric compounds with a thermally reactive silicone fluid to improve the electrical properties of polymeric compounds containing such polar additives, and The present invention relates to products with improved electrical properties consisting of polymeric electrical insulators containing polar additives treated with polar silicone fluids. Accordingly, the present invention relates to electrically insulating polymeric compounds with good electrical properties containing polar fillers or additives, in particular halogen-containing flame retardants, with good electrical properties and high flame and combustion resistance. It relates to polymer electrical insulators or compounds thereof. The method of the present invention produces electrical insulation with significantly improved electrical properties comprising a polymeric material or compound containing a halogen-containing flame retardant or composition; The polar component is heated with the silicone fluid and then combined with the components of the polymeric material or compound. Although the present invention is applicable to known and currently used polymer compositions such as rubbers or elastomers, as well as newly developed polymer compositions suitable for use in electrical insulation applications, the present invention is particularly applicable to electrical insulation applications. The present invention relates to polymeric insulators containing polyolefin polymers because they have unique properties for insulation and are widely used in such applications. Polyolefin polymeric materials that can be used in the practice of this invention include ethylene-containing polymers such as polyethylene, copolymers of ethylene and other polymerizable materials, and blends of such polymers, including copolymers. . Representative copolymers of ethylene include, for example, ethylene-propylene copolymers, ethylene-ethyl acrylate copolymers, and ethylene-methyl acrylate copolymers. The flame-resistant polyolefin polymers or compounds thereof according to the invention may further contain fillers such as bulking or reinforcing ingredients such as silica, clays or fibers, pigments, curing co-operative agents, and other customary additions. agents, such as protective (preservative) agents, such as antioxidants, modifiers, such as plasticizers, processing aids, mold release components, or lubricants, as well as polyolefin polymers or typical products formed therefrom, such as electrical insulation. Usually compounded equivalents are included. The present invention also particularly applies to, and thus includes, all of the polyolefins mentioned above in their crosslinked and thermoset state, the thermosetting being carried out by high energy irradiation, e.g. by electrons. or U.S. Patent No. 2888424, U.S. Patent No. 3079370, U.S. Patent No.
3086966 and 3214422 with heat activatable organic peroxide crosslinking agents. Suitable peroxide crosslinking curing agents have the structural formula decomposes to provide free radicals at temperatures above about 146°C (295°C). The preferred peroxide for curing polyolefins is di-α.
-cumyl peroxide, as well as tertiary diperoxides such as 2,5-dimethyl-2,4-di(t-butylperoxy)hexane and 2,5-dimethyl-
2,4-di(t-butylperoxy)hexyne-
3 and similar diperoxy and polyperoxide compounds. The highly polar flame retardants used in the practice of this invention include U.S. Pat.
Any of the halogen-containing compositions or agents used heretofore may be used, including the halogenated hydrocarbons of No. 3582518, No. 3705128, No. 3740245, and No. 3741893. For example, halogenated hydrocarbons that have been commonly used for flame resistance purposes include chlorinated paraffin, chlorinated propane, chlorinated propylene, hexachloroethane, chlorinated polythene, chlorinated polyisobutylene, polyvinyl chloride, polyvinylidene chloride, Chlorinated polyvinyl chloride, chlorinated polyphenyl, chlorinated naphthalene, hexachlorobenzene, chlorinated indene, chlorinated polystyrene, chlorinated diphenylalkane, and their brominated or other halogenated equivalents such as hexabromobiphenyl, Includes decabromobiphenyl or decabromobiphenyl oxide. Conventional halogenated hydrocarbons also include proprietary halogenated flame retardants such as Hooker Chemical Company
Dechlorane Plus515，Diamond Alkali
Company's Chlorowax, and similar products. As is customary in the use of halogen-based flame retardants or compositions, antimony oxide or an equivalent metal oxide may be included with the halogen-containing flame retardant to provide a well-known flame retardant system. Can be provided. Halogen-containing flame retardants and/or antimony oxide or the like can be used in conventional amounts or proportions to provide the degree of flame or combustion resistance needed or desired. The thermoresponsive silicone fluid of the present invention is a combination of polyfunctional methylsilicones, i.e., a major amount of dimethylsilanol and a minor amount of methylsilanol, e.g.
about 25 mole% and about 95 to about 75 dimethylsilanediol
Consisting of mole%. Blends of polyfunctional, i.e. polyol, dimethylsilanol and methylsilanol can be heated e.g.
C. Preferably above or about 175.degree. C. for several hours to react or cure. The heating time must be sufficient to raise the overall temperature of the material undergoing treatment to the above temperature level for a sufficient period of time to induce reaction of the silicone. A suitable amount of the polyfunctional silanol liquid formulation is
At least about 1%, preferably from about 2% to about 5% by weight of the combined materials. Additional optional ingredients that may be included in the practice of this invention include lead compounds such as dibasic lead phthalates, silicone gums, and fumed silica. Suitable silicone gums are gums or organopolysiloxanes condensed to rubbery, elastic, nearly solid state high molecular weight polymers. For example, typical silicone elastomers used in the compositions of the present invention are dimethylpolysiloxanes of the group having the chemical structure: Another group of silicone elastomers used in this invention are methyl-phenylpolysiloxanes and such silicones containing small amounts of vinyl groups. Further examples of silicone elastomers of the type that can be used to obtain the compositions of the invention include the organopolysiloxanes mentioned in U.S. Pat. Nos. 2,888,424 and 2,888,419; Same No. 2448756, Same No. 2457688,
Same No. 2484595, Same No. 2490357, Same No. 2521528,
Same No. 2541137, No. 3098836 and No. 3341489
Details are shown in the issue. Such high molecular weight polymers typically have a Bruckfield viscosity of about 100,000 centipoise or greater at 25°C. Fuyumed silica refers to the form of silica described in U.S. Pat. No. 2,888,424, manufactured by Godfrey L. Cabot, Inc., Boston, Mass.
This type is commercially available under the trade name Cabosil MS7. The following examples of the methods and products of the present invention, and evaluations and data compared to substantially equivalent compositions as a basis of comparison, demonstrate the improved electrical properties of the novel methods of the present invention. as well as other beneficial properties. The insulating compositions of Examples and Standard Examples of the present invention are all given in parts by weight, and the compositions of Examples and Standard Examples of the present invention were crosslinked and cured under the same conditions, tested, and evaluated. . The relative resistance to flame and combustion of various compositions of the Examples and Standards of the Invention are shown in U.S. Pat.
As described in No. 3755214 and No. 2787356
All measurements were made in accordance with the oxygen index test method specified in ASTM Test Method D-2863-70. As already known, this test indicates the proportion of oxygen in nitrogen (volume fraction) required to just maintain a flame in the test sample material. Therefore, the higher the oxygen index for a given composition, the better its resistance to flame and combustion. In accordance with the present invention, a flame retardation system of combinations of components including a brominated composition is pretreated as described below. The combination of the components providing the flame retardation system, i.e. the highly polar halogen composition and the polyfunctional silicone fluid used to pre-treat the components of the system, and the relative weight proportions of the components are as follows: It is.

Table: The above silicone fluid consisted of about 7 mole percent methylsilane triol and about 93 mole percent dimethylsilane diol. The components, consisting of a flame retardant system containing highly polar reagents, were pretreated with a thermally reactive silicone fluid. That is, the above-mentioned silicone liquid is added to the above-mentioned system component mixture in a suitable mixing device to effectively disperse it, and then the resultant mixture of the dispersed silicone and various components is heated to bring about a reaction of the silicone liquid. Ta. In this case, the product mixture is approximately 190°C (375
〓) for approximately 16 hours. Decabromodiphenyl ether in the above amounts,
The product components, pretreated with a flame retardant silicone fluid containing antimony oxide and fumed silica, were incorporated into the following crosslinked curable polyethylene electrical insulation compound. All ingredients are given on a weight basis. For comparison purposes, compositions were also prepared with substantially the same composition (all components given on a weight basis) except that the components of the flame retardation system were not pretreated with a silicone fluid. Except for the pretreatment step and the approximately 1.5 parts by weight of silicone fluid used therefor, all operations or steps in the preparation of the insulating compounds of the Examples and Standards of the Invention were identical.

[Table] Agents Polyethylene electrical insulation compositions of each of the above compositions, consisting of a standard example compound containing an unpretreated flame retardant and a compound of the present invention containing a pretreated flame retardant. , extruded onto wires to the same thickness and under identical conditions in all respects, including crosslinking and curing of the insulation. Similar samples of electric wires insulated with both of the above compositions were subjected to the same test conditions, test methods, and evaluations as follows. All samples were subjected to the "Loss of Coolant Accident"), so-called "LOCA" test (IEEE Standard 323-1974).
This test simulates the aggressive conditions potentially encountered within a nuclear reactor system. The test consists of placing an insulated wire sample in a pressurized chamber at high temperature and pressure for 110 days and then spraying the sample with water. The electrical and other properties of the electrical insulation of the wire samples for both the standard example and the present invention were as follows.

【table】

[Table] 〓
7〓14th〓No. 0.00
As indicated above, the crosslinked cured flame resistant polyolefins or compounds thereof of the present invention are particularly useful materials as dielectric insulation for electrical conductors such as wires and cables. A typical construction of an insulated wire or cable product 10 is shown in the figure, comprising a conductive metal element 12 and an overlying layer of cured polymer insulation extending around and overlying the electrical conductor. It consists of a body 14. In the figure, article 10 is illustrated in short cut form, with insulator 14 extending from the end of conductor 12.
is shown removed. In accordance with one embodiment of the present invention, the novel flame resistant polyolefins of the present invention may be used to provide and form the insulation 14 on the conductive element 12 of the wire or cable product 10. However, as understood from the above description,
The insulator may be a coating over any portion of the conductive element, and there is no need for the insulator to completely surround the conductive element unless the desired insulation effect requires it. Although the invention has been described in terms of certain specific embodiments. Many modifications are possible and are therefore intended to include all modifications that come within the spirit and scope of the invention. EM-60 Test Method After vulcanization, take a 15-foot (4.57 meter) test specimen of insulated conductor and immerse the specimen in water at least 48 hours after vulcanization. The center 10 ft (3.05 m) of this test specimen was immersed in tap water maintained at 75°C ± 1°C for 14 days, and a 21/2 ft (0.76 m) portion of each end of the specimen was held above the water to prevent leakage. Insulate. Place a tight-fitting cover directly above the water surface and provide suitable watertight bushings at each end of the specimen. Keep the water level constant. The capacitance of the insulation is measured after 1, 7, and 14 days of immersion at an average stress of 80 V/mil at approximately 60 hertz frequency. The power factor of the insulation is measured after 1 and 14 days of immersion at average stresses of 80 and 40 volts/mil. The 1-14 day capacitance increase and the 7-14 day capacitance increase are expressed as percentages of the 1-day and 7-day values, respectively. Power factor is expressed with an accuracy of 0.1%. The stability factor here is the difference between the % power factor of 80 volts/mil and the % power factor of 40 volts/mil after the test specimen is immersed in water at 75° C.±1° C. for a specified period of time. The alternation stability rate is the stability rate after 14 days minus the stability rate after 1 day. Calculating the dielectric constant (relative permittivity) of an insulator at 60 Hz is as follows. Dielectric constant = 13600C log ₁₀ D/d where C is the capacitance in microfarads over a 10 foot (3.05 meter) section, D is the diameter above the insulation, and d is the diameter below the insulation.

[Brief explanation of the drawing]

The figure shows a wire or cable product 10 insulated according to the method of the present invention. DESCRIPTION OF SYMBOLS 10... Electric wire or cable, 12... Conductive metal element, 14... Cured polymer insulator.

Claims (1)

[Scope of Claims] 1. A flame retardant containing a halogen-containing organic compound is mixed with 95-75 mol% dimethylsilanediol and 5
- A halogen-containing flame retardant composition for use in electrically insulating polymeric compounds heat treated with a heat-reactive silicone fluid in combination with 25 mole percent methylsilane triol. 2. The halogen-containing flame retardant composition of claim 1, wherein the heat-reactive silicone liquid consists of 7 mol% methylsilane triol and 93 mol% dimethylsilane diol. 3. A halogen-containing flame retardant composition according to any one of claims 1 or 2, wherein the thermally reactive silicone fluid is heated to at least 150°C for a sufficient time to cause a reaction.