US2575733A - Flexible mica compositions - Google Patents

Flexible mica compositions Download PDF

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Publication number
US2575733A
US2575733A US714818A US71481846A US2575733A US 2575733 A US2575733 A US 2575733A US 714818 A US714818 A US 714818A US 71481846 A US71481846 A US 71481846A US 2575733 A US2575733 A US 2575733A
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US
United States
Prior art keywords
pine tar
mica
heat
mica flakes
treated
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.)
Expired - Lifetime
Application number
US714818A
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English (en)
Inventor
Earl L Schulman
George S Reeder
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.)
Westinghouse Electric Corp
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Westinghouse Electric Corp
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
Priority to FR956928D priority Critical patent/FR956928A/fr
Application filed by Westinghouse Electric Corp filed Critical Westinghouse Electric Corp
Priority to US714818A priority patent/US2575733A/en
Priority to ES0180764A priority patent/ES180764A1/es
Application granted granted Critical
Publication of US2575733A publication Critical patent/US2575733A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • 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
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B26/00—Compositions of mortars, concrete or artificial stone, containing only organic binders, e.g. polymer or resin concrete
    • C04B26/02—Macromolecular compounds
    • C04B26/22—Natural resins, e.g. rosin
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J195/00—Adhesives based on bituminous materials, e.g. asphalt, tar, pitch
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
    • C04B2111/00612—Uses not provided for elsewhere in C04B2111/00 as one or more layers of a layered structure
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2666/00—Composition of polymers characterized by a further compound in the blend, being organic macromolecular compounds, natural resins, waxes or and bituminous materials, non-macromolecular organic substances, inorganic substances or characterized by their function in the composition
    • C08L2666/54—Inorganic substances
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/25—Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
    • Y10T428/251—Mica

Definitions

  • This invention relates to insulating compositions, and in particular, to mica bonded with a relatively permanently flexible binder for use in laminated insulation.
  • insulating material composed of mica flakes and a flexible, non-hardening binder, so that the insulating material will remain substantially permanently flexible and hardening with age will not occur during storage of the material and in subsequent use.
  • Flexible mica insulation is particularly desirable for wrapping and tapes.
  • mica bonded with a permanently flexible binder when applied to members is capable of distributing stresses more effectively than a rigid insulating member would, and, therefore, will withstand physical stresses better.
  • the object of this invention is to provide for a relatively flexible mica insulation embodying heat treated pine tar binder.
  • a further object of the invention is to provide ,ior bonding mica with heat-treated pine tar to produce a substantially permanently flexible composite insulation.
  • a still further object is to provide .for heat.- treating pine tar to render it usable iforibonding mica.
  • Fig. ,1 is an enlarged view in vertical cross-section of mica insulation
  • Fig. 2 is an enlarged view in vertical crosssection of a modification
  • Fig. 3 is an enlarged view in vertical crosssection of another modification.
  • Fig. .4 is a view in perspective of a slot cell.
  • a substantially permanently flexible mica insu'lationis prepared by bonding mica flakes with heatetreated pine tar.
  • Pine tar is produced by the destructive distillation of pine wood wherein a mixture of various volatile materials distill from the wood, and in subsequent refining of the mixture the pine tar is the last volatile material given off.
  • iThgspecific since it consists of a variable mixture having a characteristic odor composed of tarry constituents, light oils and other volatile ingredients.
  • .Crude pine tar sold to the trade is entirely lunsuitable for use as a mica bond. It will notbond mica flakes together. Mica flakes treatedwith crude pine tar fall apart. Other properties of the crude pine tar, such as variable-composition and electrical characteristics further would render it unsuited for this application.
  • heat treated'pine tar will refer to crude pine'tar heat treated at the temperature above indicated for a sufficient time to drive ofi all the oils and other volatile matter.
  • the heat treatment is carried out in the open atmosphere. If enclosed vessels connected to a vacuum pump are employed, lower temperatures 'or a shorter time period will produce .the same product.
  • medium retort pine tar was Approximately 35% of its weight in oils and other volatile matter was driven off in this time.
  • the viscosity of the heat treated pine tar was in the range of 40 to '70 poises.
  • a heat-treated product having a viscosity of from about 10 to poises may be employed in the practice of the invention.
  • Heavy retort pine tar requires about 4 hours at 225 C. to renderit satisfactory for mica bond.- .ing and less than 30% volatile is driven off. Light retort pine tar has more volatilepresent andn a y requirethe longest heat-treatment time.
  • Fig. 1 of the drawing there is shown an enlarged vertical cross-section through a sheet of mica insulation Ill so prepared comprising the mica flakes i2 bonded with the heat-treated pine tar I4.
  • a twenty mil sheet thick of mica flakes bonded with 15% of its weight of a composition composed of by weight of treated pine tar and 5% Vinsol resin had the following properties on being tested:
  • a fibrous base material particularly where producing extremely thin material of the order of 4 mils in thickness to secure abrasion and scuff resistance.
  • Suitable fibrous reinforcing base materials are rope paper,.cement paper, cambric, glass fiber cloth, asbestos paper and asbestos cloth.
  • the preparation of a flexible mica tape is as follows. Referring to Fig. 2 of the drawing, the insulation 20 is prepared from 1 mil thick rope paper 22 covered with a 2 mil thick layer 24 of mica flakes 26, then the mica flakes are sprinkled with a 40% solution of the heat-treated pine tar alone or with a, small proportion of a hardening agent as above described.
  • a top sheet 30 of 1 mil thick rope paper similar to the bottom sheet is applied over the mica flakes.
  • the sheet insulation so produced may be slit into tapes of any convenient width. These tapes have been stored for periods of a year without any appreciable change in flexibility.
  • Illustrated in Fig. 3 is another form of composite insulation 32 comprising a layer of mica flakes 34 bonded with the heat treated pine tar 36 and an upper and lower layer of glass cloth 38 and 40 applied thereto.
  • slot cell liner 50 may be produced by combining an outer backing 52 of fish paper and mica flakes in a layer 54 of suitable thickness and impregnating the applied mica flakes with the heat-treated pine tar, pref-- erably with about 5% to 10% of one of the hardening agents listed herein. After drying the composite material at a temperature of about 100 C., the mica flakes may be covered with a thin glass fiber cloth 56 to provide for abrasion resistance. The composite material may be compressed in a heated press at 10 pounds per square inch at a temperature of about C. for a few minutes. The compressed material. may be out and shaped into slot cell liners 50.
  • the fish paper 52 will provide a relatively rigid backing which will permit the slot cell liners to be easily inserted into the slots in motor and generator armatures.
  • the glass cloth 56 will permit the ready introduction of the windings into the slot cell without damage or undue shifting of the mica flakes.
  • the flexible heat-treated pine tar binder will accommodate elongation and contraction of the conductors during use of the dynamoelectric machine.
  • the slot cell liners will not become rigid due to the permanently flexible nature of the heat-treated pine tar.
  • the pressing of mica insulation carrying the heat-treated pine tar bonding agent is primarily to secure good consolidation.
  • the press is heated in order to reduce the viscosity of the pine tar bonding agent so that it will distribute uniformlyunder moderate pressures of the order of a few pounds per square inch. Obviously higher pressures may be employed, but are not critical.
  • Numerous forms of insulation embodying mica flakes and the heat-treated pine tar bonding agent disclosed herein may be prepared. Insulation composed of mica flakes with various reinforcing and backing materials may be produced using the heat-treated pine tar bonding agent of this invention.
  • Insulating material comprising in combination mica flakes and a bonding agent applied to the mica flakes, the bonding agent comprising heat-treated pine tar of a viscosity of from to 100 poises free from oil and other volatile material corresponding to the product derived by heating pine tar for from about 3 to 8 hours at a temperature of from about 200 to 250 C. under atmospheric pressure, the heat treatment driving off the oil and other volatiles in the pine tar.
  • Insulating material comprising in combination mica flakes and a bonding agent applied to the mica flakes, the bonding agent comprising heat-treated pine tar of a viscosity of from 10 to 100 poises free from oil and other volatile material derived by heating pine tar for from about 3 to 8 hours at a temperature of from about 200 C. to 250 C., the heat treatment driving off the oil and other volatiles in the pine tar and up to 10% of the weight of the pine tar of a mica bonding agent selected from the group consisting of shellac, alkyd resins and the residue from solvent extracted pine wood pitch resin.
  • a laminated electrically insulating material comprising a fibrous sheet, mica flakes applied to the fibrous sheet and a bonding agent for binding the fibrous sheet and the mica flakes into a whole, the bonding agent comprising heattreated pine tar of a viscosity of from 10 to 100 poises free from oil and other volatile material derived by heating pine tar for from about 3 to 8 hours at a temperature of from about 200 C.
  • the heat treatment driving off the oil into a whole, the bonding agent comprising heattreated pine tar of a viscosity of from 10 to 100 poises free from oil and other volatile material derived by heating pine tar for from about 3 to 8 hours at a temperature of from about 200 C. to 250 0., the heat treatment driving 01f the oil and other volatiles in the pine tar, and up to 10% of the weight of the pine tar of a mica bonding agent selected from the group consisting of shellac, alkyd resins and the residue from solvent extracted pine wood pitch resin.
  • a laminated electrically insulating material comprising, in combination, a base sheet of paper, mica flakes applied to the base, a top sheet of paper coextensive with the base sheet and a bonding agent applied to the mica flakes to unite the base and top sheets of paper therewith, the bonding agent comprising heat-treated pine tar of a viscosity of from 10 to 100 poises free from oil and other volatile material derived by heating pine tar for from about 3 to 3 hours at a temperature of from about 200 C. to 250 0., the heat treatment driving off the oil and other V013: tiles in the pine tar.
  • a laminated electrically insulating material comprising, in combination, a base comprising a fabric of glass fibers, mica flakes applied to the base and a bonding agent applied to the mica flakes and glass fabric to unite them into a whole, the bonding agent comprising heat-treated pine tar of a viscosity of from 10 to poises free from oil and other volatile material derived by heating pine tar for from 3 to 8 hours at a temperature of from about 200 C. to 250 C., the heat treatment driving off the oil and. other volatiles in the pine tar.
  • a laminated electrically insulating material comprising, in combination, a base comprising a fabric of asbestos fibers, mica flakes applied to the base and a bonding agent applied to the mica flakes and asbestos fabric to unite them into a whole, the bonding agent comprising heattreated pine tar of'a viscosity of from 10 to 100 poiess free from oil and other volatile material derived by heating pine tar for from about 3 to 8 hours at a temperature of from about 200 C. to 250 C., the heat treatment driving off the oil and other volatiles in the pine tar.
  • An adhesive composition comprising heattreated pine tar of a viscosity of from 10 to 100 poises substantially free of oils and other volatile matter, corresponding to the product derived by heating pine tar for from about 3 to 8 hours at a temperature of from about 200 C. to 250 C., exposed to atmospheric pressure to free the pine tar from the coils and other volatile material.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Structural Engineering (AREA)
  • Inorganic Insulating Materials (AREA)
US714818A 1946-12-07 1946-12-07 Flexible mica compositions Expired - Lifetime US2575733A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
FR956928D FR956928A (en, 2012) 1946-12-07
US714818A US2575733A (en) 1946-12-07 1946-12-07 Flexible mica compositions
ES0180764A ES180764A1 (es) 1946-12-07 1947-12-03 MEJORAS INTRODUCIDAS EN LA PREPARACIoN DE MATERIALES AISLADORES

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US714818A US2575733A (en) 1946-12-07 1946-12-07 Flexible mica compositions

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US2575733A true US2575733A (en) 1951-11-20

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ES (1) ES180764A1 (en, 2012)
FR (1) FR956928A (en, 2012)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2980564A (en) * 1956-07-07 1961-04-18 Bbc Brown Boveri & Cie Method of wrapping windings of electric machines
US3079277A (en) * 1959-11-16 1963-02-26 Lord Mfg Co Damped structure
US3226286A (en) * 1961-11-07 1965-12-28 Budd Co Dehydrated mica products and method of making same

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US764812A (en) * 1902-08-08 1904-07-12 Mica Insulator Company Electrical insulator.
US1146455A (en) * 1913-07-09 1915-07-13 Wilhelm Schumacher Binding means for briquets.
US1784737A (en) * 1927-08-15 1930-12-09 Bakelite Ltd Manufacture of mica tubes and sheets
US2054356A (en) * 1934-10-01 1936-09-15 New England Mica Co Bonded product with long temperature range binders
US2359972A (en) * 1941-11-07 1944-10-10 Hercules Powder Co Ltd Shellac substitute
US2363324A (en) * 1942-05-23 1944-11-21 Westinghouse Electric & Mfg Co Electrical insulation
US2379662A (en) * 1944-10-04 1945-07-03 Wiley C Smith Process for treating crude pine tar
US2410884A (en) * 1943-01-26 1946-11-12 Utility Fabrics Company Inc Composite fabric
US2462228A (en) * 1944-05-24 1949-02-22 Westinghouse Electric Corp Insulating material

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US764812A (en) * 1902-08-08 1904-07-12 Mica Insulator Company Electrical insulator.
US1146455A (en) * 1913-07-09 1915-07-13 Wilhelm Schumacher Binding means for briquets.
US1784737A (en) * 1927-08-15 1930-12-09 Bakelite Ltd Manufacture of mica tubes and sheets
US2054356A (en) * 1934-10-01 1936-09-15 New England Mica Co Bonded product with long temperature range binders
US2359972A (en) * 1941-11-07 1944-10-10 Hercules Powder Co Ltd Shellac substitute
US2363324A (en) * 1942-05-23 1944-11-21 Westinghouse Electric & Mfg Co Electrical insulation
US2410884A (en) * 1943-01-26 1946-11-12 Utility Fabrics Company Inc Composite fabric
US2462228A (en) * 1944-05-24 1949-02-22 Westinghouse Electric Corp Insulating material
US2379662A (en) * 1944-10-04 1945-07-03 Wiley C Smith Process for treating crude pine tar

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2980564A (en) * 1956-07-07 1961-04-18 Bbc Brown Boveri & Cie Method of wrapping windings of electric machines
US3079277A (en) * 1959-11-16 1963-02-26 Lord Mfg Co Damped structure
US3226286A (en) * 1961-11-07 1965-12-28 Budd Co Dehydrated mica products and method of making same

Also Published As

Publication number Publication date
FR956928A (en, 2012) 1950-02-10
ES180764A1 (es) 1948-01-16

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