EP0175635A2 - Cylindres de mica de haute densité résistant à l'humidité - Google Patents

Cylindres de mica de haute densité résistant à l'humidité Download PDF

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Publication number
EP0175635A2
EP0175635A2 EP85630151A EP85630151A EP0175635A2 EP 0175635 A2 EP0175635 A2 EP 0175635A2 EP 85630151 A EP85630151 A EP 85630151A EP 85630151 A EP85630151 A EP 85630151A EP 0175635 A2 EP0175635 A2 EP 0175635A2
Authority
EP
European Patent Office
Prior art keywords
percent
mica
weight
paper
binder
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP85630151A
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German (de)
English (en)
Other versions
EP0175635A3 (fr
Inventor
Arthur F. Doyle
Dennis J. Sklarski
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Essex Furukawa Magnet Wire USA LLC
Original Assignee
Essex Group LLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Essex Group LLC filed Critical Essex Group LLC
Publication of EP0175635A2 publication Critical patent/EP0175635A2/fr
Publication of EP0175635A3 publication Critical patent/EP0175635A3/fr
Withdrawn legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B31—MAKING ARTICLES OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER; WORKING PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31F—MECHANICAL WORKING OR DEFORMATION OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31F1/00—Mechanical deformation without removing material, e.g. in combination with laminating
    • B31F1/0003—Shaping by bending, folding, twisting, straightening, flattening or rim-rolling; Shaping by bending, folding or rim-rolling combined with joining; Apparatus therefor
    • B31F1/0045—Bending or folding combined with joining
    • B31F1/0048—Bending plates, sheets or webs at right angles to the axis of the article being formed and joining the edges
    • B31F1/0051—Bending plates, sheets or webs at right angles to the axis of the article being formed and joining the edges for making articles of definite lentgh
    • B31F1/0054—Bending plates, sheets or webs at right angles to the axis of the article being formed and joining the edges for making articles of definite lentgh using internal forming surfaces, e.g. mandrels
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/20—Macromolecular organic compounds
    • D21H17/33—Synthetic macromolecular compounds
    • D21H17/46—Synthetic macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
    • D21H17/59—Synthetic macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B19/00—Apparatus or processes specially adapted for manufacturing insulators or insulating bodies
    • H01B19/02—Drying; Impregnating
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
    • H01B3/02—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of inorganic substances
    • H01B3/04—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of inorganic substances mica

Definitions

  • the field of art to which this invention pertains is mica containing composite material.
  • Mica containing cylinders have been used for many years as electrical insulating structures such as standoffs.
  • such mica cylinders are composite structures formed by impregnating mica sheeting with a polymeric binding agent and wrapping the sheeting about a form. The mica cylinder is then heated to cure the binder and form the cylinder.
  • Such articles have good dielectric strength, heat stability and are relatively inexpensive.
  • these mica products are susceptible to attack by moisture, are relatively easy to fracture, and are not always uniform in thickness or dimensionally stable at high temperatures.
  • such mica products are not stain resistant and have relatively poor machinability characteristics.
  • the present invention is directed toward a relatively high density, mica cylinder comprising one or more mica papers which are impregnated with about 5 percent to about 14 percent by weight of a polysiloxane binder which contains about 1 percent to about 4 percent by weight of an organic titanate and about 0.5 percent to about 2 percent by weight of a metal naphthenate.
  • a polysiloxane binder which contains about 1 percent to about 4 percent by weight of an organic titanate and about 0.5 percent to about 2 percent by weight of a metal naphthenate.
  • Such mica cylinders have improved moisture resistance, thermal stability, dimensional stablility and strength and stain resistance over that of the prior art.
  • such structures are scour resistant and have improved machinabilty.
  • Another aspect of the invention is a method of forming such cylinders by impregnating mica paper with about 5 percent to about 20 percent by weight of a polysiloxane binder which contains about 1 percent to about 4 percent of an organic titanate and about 0.5 percent to about 2 percent by weight of a metal naphthenate, wrapping the impregnated papers about a form and densifying and curing the binder under pressure and temperature, while restrained, to form the improved moisture resistant cylinders.
  • the Figure is a schematic of a continuous belt rolling system which may be used to form the mica cylinders of the present invention.
  • cylinder or cylindrical should not be limited to a structure having a closed curve cross-section but should include any polygonal cross-sectional structure.
  • the mica paper used to practice this invention may comprise any conventional, continuous, thin mica paper, however, those made from muscovite or phlogopite mica are preferred. Which material is selected depends on the properties desired in the end product. Typically, where high dielectric properties are desired, muscovite will be used, whereas, if high temperature properties are desired, the phlogopite is generally selected.
  • the mica paper is typically in the form of conventional water-disintegrated, integrated mica paper which may be prepared using conventional techniques. The thickness of the mica paper characteristically ranges from about 50.8 ⁇ m to about 50Spm with about 127 ⁇ m being preferred.
  • the binder which is used to form the mica laminate comprises any of the thermally crosslinkable silicone polymer systems which are used to form other mica laminates.
  • the selection of which system to use depends on the properties desired in the final laminate. Since many of the mica laminates find uses in high temperature environments (about 359°F, 180°C), it is preferred that the binder system used be thermally stable at these elevated temperatures.
  • the preferred systems are methyl-phenyl polysiloxane or methylpolysiloxane which are available from D ow Corning Corporation, Midland, Michigan, as Dow Corning 4-3136, Dow Corning 2104 or 2105 or 2106.
  • polysiloxane system used to practice this invention should not condense or outgas excessively while curing, for this may cause the formation of a defective laminate through the formation of blisters or voids in the laminate.
  • Any compatible organic titanate including the neoalkoxy titanates (available from Kenrich Petrochemicals Inc., Bayonne, New Jersey), may be mixed with the polymer system in the range from about 1% to about 4 percent by weight with about 2 percent being preferred.
  • the titanates which are most useful are those which are soluble in the polymer system, i.e. polysiloxane, and do not promote rapid cross-linking of the polymer which will shorten the shelf life of the system. Whether a titanate causes too rapid cross-linking or not is dependent on the manufacturing process which is used to form the cylinders. A manufacturing process which is fast, may tolerate a faster cross-linking process while a slower process will produce an inferior product.
  • Some typical titanates are listed in Table I, with the preferred titanates being those of the monoalkoxy pyrophosphato titanate family.
  • Conventional metal naphthenate driers associated as soap driers, are added to the base polymer in concentrations from about 0.5 percent to about 2 percent, by weight of the polymer, with about 1 percent being preferred.
  • metallic soap driers are manganese naphthenate, zinc naphthenate, tin naphthenate, cobalt naphthenate, etc. It is believed that the addition of these naphthenate driers coupled with the titanates in the relative properties recited are what give these mica laminates their superior moisture resistant properties without deteriorating the other properties recited.
  • the solvents which are typically used as carriers for the binder, are organic in nature and may be aliphatic or aromatic with toluene or xylene being preferred.
  • the solvent should be chosen for its compatibility with all of the binder constituents.
  • the amount of solvent is not critical and is typically in the range of from about 40 percent to about 60 percent of the total volume of the solution.
  • a binder solution containing the above constituents to be applied to the mica paper is typically prepared as follows: (It should be noted that the sequence of addition of the ingredients is important. The titanate should be added first, then the naphthenate and then the polysiloxane. The sequence is desirable as it allows for a smooth dissolution of the constituent.)
  • Solvent is placed in a container in which the binder will be prepared.
  • the titanate' is then added to the solvent and is stirred until the titanate is dissolved and the solution is clear. Typically, this is done at ambient temperatures about 60°F (15°C) to about 85°F (30°C).
  • the naphthenate drier is added to the solution and stirred until dissolved. Again, this is done at ambient temperatures.
  • To this solution is then added the polysiloxane and the mixture is stirred until homogenous, typically for about one-half hour to one hour at ambient temperatures.
  • the polysiloxane is added in quantities such that the titanate and naphthenate will be in the proper concentrations when the solvent is removed.
  • the mica paper is removed from the roll and placed on a flat surface, i.e. a table, conveyer belt, etc., and the paper is impregnated with the binder by any conventional technique, i.e. dripping.
  • the amount of the binder applied is such that the final cylinder contains about 5 percent to about 14 percent by weight binder and the application should be such that the binder is evenly distributed throughout the paper.
  • Other conventional impregnation techniques may be used to apply the binder to the paper such as dipping, or roll soaking, spraying, brushing, etc., and in certain processes, it may be desirable to coat both sides of the paper.
  • the aromatic solvent present in the binder is then removed by exposing the paper and binder to temperatures high enough to cause the solvent to evaporate, but not so high as to cause the polymer to polymerize. Typically, these temperatures are about 250°F (121°C) to about 275°F (135°C). Typically, this is done by passing the paper through an oven or exposing it to radiant heat, etc. The paper is then cooled to ambient temperatures forming a relatively stiff paper sheet.
  • the impregnated mica paper may be further processed to more uniformly distribute the binder throughout the paper and densify it prior to forming it into a cylinder under heat and pressure.
  • this process takes place at temperatures of about 200°F (93.3°C) to about 275°F (135°C) under sufficient pressure to cause the polymer to flow throughout the mica paper.
  • the pressures generally range from about 6.89 bar to about 31.04 bar.
  • T his process may be done in conventional press equipment. The length of time the paper is pressed and the particular pressures and temperature parameters to which this processing takes place will vary with the thickness of the paper and the amount of polymer present as well as the particular polymer system. Note Example.
  • the impregnated paper is then heated to about 350°F (176.6°C) to about 400°F (204.4°C) to make the paper pliable enough to be wrapped about the form.
  • This may be done by placing the sheet onto a heated platen or placed under a heat source, i.e. infrared lamps or through an oven. Since these temperatures are above the polymerization temperature of the polymer, this heating process must be done quickly so that the polymerization does not advance to such a state as to prevent the material from being rolled.
  • the determination as to when the paper is pliable enough may be made by checking the flexibility of one corner of the paper. When it bends up easily, it is pliable enough. The optimum condition, temperature and time, will vary with each system and with different thickness papers so this would have to be determined on a case by case basis.
  • the paper may then be formed into a tubular shape. Typically this is done by wrapping the pliable mica paper about an arbor or form. This may be done by hand-wrapping or conventional rolling machines may be used.
  • One such machine-wrapping process is shown in the Figure wherein the wrapping machine 10 has a moving belt 20 on rollers 25 which pass over the heated surface 30 carrying the mica sheets 40.
  • An arbor 50 which typically has been coated with a release agent, i.e. Teflon, silicone, etc., is placed in a bend 55 in the belt 20 so that the paper is wrapped about the arbor 50 as the belt 20 passes around it.
  • a release agent i.e. Teflon, silicone, etc.
  • the bend may be made by placing a rod 60 so as to maintain the belt contact with the arbor for sufficient time to roll the mica onto it.
  • the tube is wrapped to a desired thickness by either winding a series of mica papers about the mandrel or by winding the mica paper from a continuous sheet. No specific tension need be applied when wrapping the impregnated paper about the forming mandrel.
  • the paper need only be taut enough to make a relatively smooth and neat appearing structure which is in the desired form.
  • an additional adhesive layer may be applied to the inside portion, (that portion which will contact the arbor), of the paper prior to it being wound. This will increase the interlaminar adhesion of the tube and form a better, more stable tubular structure.
  • the wall thickness of these cylinders is typically from about 0.025cm. to about 2.54 cm.
  • the polymeric binder is cured by heating the tube to about 392°F (200°C) to about 1000°F (537.8°C) causing the binder to cross-link. This is typically done in an oven.
  • the residency time of the cylinders at these temperatures will vary depending on the wall thickness and amount of polymer present in the paper. However, typical times are about 2 hours to about 4 hours. It is important, to restrain the tubes while they are being cured to prevent them from unraveling. This may be done by using a metal mold or by wrapping the structure in a removable layer such as glass cloth or by placing it in a knitted or braided sleeve of fiberglass and drawing it taut. The constraint need not be great but should be present.
  • the tube is cured, it is cooled to ambient temperature and then removed from the constraints and, if not in the finished shape, is machined to the desired dimensions.
  • the resulting mica cylinders are thermally stable, excellent electrical insulators and have remarkably high moisture resistance as well as very high fracture toughness. All of these properties make them excellent candidates to replace conventional ceramic or glass components which are used in the electrical industry. In addition, these cylinders are not brittle and are dimensionally stable when heated to operating temperatures which makes them superior to glass or ceramic units. In addition, these cylinders possess outstanding dielectric properties.
  • a mica cylinder was prepared according to the present invention as follows:
  • the paper was then serially placed on a platen 30 as shown in Figure 1 and heated at 232 "C for about 30 seconds to 1 minute. They were then wound around a 1.27 cm. arbor which had been treated with a silicone release agent. The arbor and the uncured mica cylinders were then placed into a glass fiber braid sleeve which was drawn taut about the tube and the arbor. The restrained cylinder was then placed in an oven in a vertical position, and heated to 260°C for 4 hours to cure the binder material. The cylinders were then cooled and the restraint was removed and the arbor was taken out. The resulting tube had an I . D . of 1.27 cm. and a wall thickness of 762 ⁇ m . In addition, certain properties of the tube were tested and are shown in the table below:
  • the superior moisture resistance of these products is a result of surprisingly improved wetting of the mica by the silicons polymer. It may be that the naphthenate and the titanate together create an improved chemical bridge between the mica and the silicone resulting'in this improved property as well as the improved fracture toughness and thermal stability.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Inorganic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Laminated Bodies (AREA)
  • Manufacturing Of Tubular Articles Or Embedded Moulded Articles (AREA)
  • Insulating Bodies (AREA)
  • Inorganic Insulating Materials (AREA)
EP85630151A 1984-09-11 1985-09-05 Cylindres de mica de haute densité résistant à l'humidité Withdrawn EP0175635A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US64934884A 1984-09-11 1984-09-11
US649348 1984-09-11

Publications (2)

Publication Number Publication Date
EP0175635A2 true EP0175635A2 (fr) 1986-03-26
EP0175635A3 EP0175635A3 (fr) 1986-09-03

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ID=24604403

Family Applications (1)

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EP85630151A Withdrawn EP0175635A3 (fr) 1984-09-11 1985-09-05 Cylindres de mica de haute densité résistant à l'humidité

Country Status (3)

Country Link
EP (1) EP0175635A3 (fr)
JP (1) JPS61127654A (fr)
BR (1) BR8504373A (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0179731A2 (fr) * 1984-10-22 1986-04-30 Essex Group Inc. Titanate de néoalkoxy dans des laminés à haute densité en mica
EP0217726A1 (fr) * 1985-09-30 1987-04-08 Essex Group Inc. Produit ondulé de mica
GB2225331A (en) * 1988-11-04 1990-05-30 Tioxide Group Plc Curable polysiloxane compositions
EP3819114A1 (fr) 2019-11-06 2021-05-12 COGEBI société anonyme Structures en sandwich à base de mica
CN113096901A (zh) * 2021-04-01 2021-07-09 湖北平安电工科技股份公司 一种云母管的制造方法

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2914426A (en) * 1956-08-09 1959-11-24 Gen Electric Method of rendering mica paper moisture resistant and article produced thereby
US2949150A (en) * 1957-07-16 1960-08-16 Westinghouse Electric Corp Flexible bonded mica insulation
DE1947677A1 (de) * 1968-09-17 1970-04-02 Minnesota Mining & Mfg Aus grossen Schuppen hergestellte Glimmerisolierung
US4371579A (en) * 1980-10-09 1983-02-01 Westinghouse Electric Corp. Fire-resistant filler sheet laminates
US4374892A (en) * 1981-06-03 1983-02-22 Essex Group, Inc. Moisture resistant insulating mica tape comprising a monoalkoxy titanate

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2914426A (en) * 1956-08-09 1959-11-24 Gen Electric Method of rendering mica paper moisture resistant and article produced thereby
US2949150A (en) * 1957-07-16 1960-08-16 Westinghouse Electric Corp Flexible bonded mica insulation
DE1947677A1 (de) * 1968-09-17 1970-04-02 Minnesota Mining & Mfg Aus grossen Schuppen hergestellte Glimmerisolierung
US4371579A (en) * 1980-10-09 1983-02-01 Westinghouse Electric Corp. Fire-resistant filler sheet laminates
US4374892A (en) * 1981-06-03 1983-02-22 Essex Group, Inc. Moisture resistant insulating mica tape comprising a monoalkoxy titanate

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0179731A2 (fr) * 1984-10-22 1986-04-30 Essex Group Inc. Titanate de néoalkoxy dans des laminés à haute densité en mica
EP0179731A3 (fr) * 1984-10-22 1987-08-26 Essex Group Inc. Titanate de néoalkoxy dans des laminés à haute densité en mica
EP0217726A1 (fr) * 1985-09-30 1987-04-08 Essex Group Inc. Produit ondulé de mica
GB2225331A (en) * 1988-11-04 1990-05-30 Tioxide Group Plc Curable polysiloxane compositions
US5032660A (en) * 1988-11-04 1991-07-16 Tioxide Group Plc Curable compositions
GB2225331B (en) * 1988-11-04 1992-02-19 Tioxide Group Plc Curable compositions
EP3819114A1 (fr) 2019-11-06 2021-05-12 COGEBI société anonyme Structures en sandwich à base de mica
WO2021089382A1 (fr) 2019-11-06 2021-05-14 Cogebi Société Anonyme Structures sandwich à base de mica
CN113096901A (zh) * 2021-04-01 2021-07-09 湖北平安电工科技股份公司 一种云母管的制造方法

Also Published As

Publication number Publication date
EP0175635A3 (fr) 1986-09-03
BR8504373A (pt) 1986-07-08
JPS61127654A (ja) 1986-06-14

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