US3903352A - Coated electrical insulating paper and method of making it - Google Patents

Coated electrical insulating paper and method of making it Download PDF

Info

Publication number
US3903352A
US3903352A US13106071A US3903352A US 3903352 A US3903352 A US 3903352A US 13106071 A US13106071 A US 13106071A US 3903352 A US3903352 A US 3903352A
Authority
US
United States
Prior art keywords
paper
electrical insulating
insulating paper
water
percent
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
Other languages
English (en)
Inventor
Kurt Suter
John H Matthews
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.)
Kimberly Clark Corp
Original Assignee
Kimberly Clark 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
Application filed by Kimberly Clark Corp filed Critical Kimberly Clark Corp
Priority to US13106071 priority Critical patent/US3903352A/en
Priority to GB29472A priority patent/GB1381331A/en
Priority to DE2202436A priority patent/DE2202436C2/de
Priority to JP1131772A priority patent/JPS5522886B1/ja
Priority to FR7204317A priority patent/FR2131954B1/fr
Priority to FI746/72A priority patent/FI58703C/fi
Priority to IT2281272A priority patent/IT955154B/it
Application granted granted Critical
Publication of US3903352A publication Critical patent/US3903352A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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
    • H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
    • H01B3/48—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances fibrous materials
    • H01B3/485—Other fibrous materials fabric
    • 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
    • Y10T428/31504—Composite [nonstructural laminate]
    • Y10T428/31725—Of polyamide
    • Y10T428/31768—Natural source-type polyamide [e.g., casein, gelatin, etc.]
    • Y10T428/31772—Next to cellulosic
    • Y10T428/31775—Paper
    • 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
    • Y10T428/31504—Composite [nonstructural laminate]
    • Y10T428/31855—Of addition polymer from unsaturated monomers
    • Y10T428/3188—Next to cellulosic
    • Y10T428/31895—Paper or wood
    • 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
    • Y10T428/31504—Composite [nonstructural laminate]
    • Y10T428/31971—Of carbohydrate
    • Y10T428/31975—Of cellulosic next to another carbohydrate
    • 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
    • Y10T428/31504—Composite [nonstructural laminate]
    • Y10T428/31971—Of carbohydrate
    • Y10T428/31975—Of cellulosic next to another carbohydrate
    • Y10T428/31978—Cellulosic next to another cellulosic
    • Y10T428/31986—Regenerated or modified

Definitions

  • the coating material 18 252/63; 260/913 VA; 428/511; 533; present to the extent of between 2 and 15 percent of 428/536 the total weight of the coated paper.
  • the coating material 18 428/476 51 1, 533 536 soluble in water within a first range of temperatures and insoluble in water within a second range of tem- [56] References Cited peratures.
  • the coating material Prior to application of the coating material UNITED STATES PATENTS to the paper, the material is washed in water within the second range of temperatures to remove alkali 1.733524 10/1929 Bradner t. 117/156 metals. and thfireafter the material is dissolved in Egg ss l water within the first temperature range to produce an 2 3 4/1950 117/157 aqueous solution for application to the paper.
  • the 2526330 10/1950 Clark 117/113 coating material may be methyl cellulose, starch, poly- 2,642,420 6/1953 Kenyon et al.. 260/913 vinyl alcohol, of P 2,7l2,539 7 1955 Nu ent et al..
  • Paper intended for use in electrical insulating applications where high dielectric strength is required, as in capacitors for example, is made on Fourdrinier papermachines, using specially purified, very highly beaten kraft woodpulp.
  • Such paper is essentially film-like in character, i.e., it is substantially free of holes and of internal voids, and has extremely low permeability to fluids.
  • the surface of capacitor paper is rough or toothy on a microscopic scale. This fine scale roughness is an important advantage in the use of paper as electrical insulation, since it provides passages for the ingress of liquid impregnants between the layers of insulation.
  • a thin spot results which represents a point of dielectric weakness and potential dielectric failure.
  • the advantage of paper insulation having maximum dielectric strength with minimum thickness is not limited to capacitors, but is generally useful in making electrical devices. For example, such paper wrapped around the wires forrnng the windings of transformers permit the size of a transformer to be reduced without reducing its power-handling capcity.
  • the invention is predicated upon the discovery that the application to the paper surface of dilute solutions of certain water-soluble, film-forming polymers produces dramatic increases in the dielectric strength of the paper. For example, an amount of coating which increases the weight per unit area of the paper by less than 4 percent, can increase dielectric strength by as much as percent. Put another way, the improved paper of a given total basis weight, including both fiber and surface coating according to this invention, is superior in dielectric strength to conventional paper of the same weight, composed entirely of fiber.
  • the invention is to be distinguished from socailed lacquered insulating or capacitor paper wherein a continuous coating of material is applied to the paper surface thereby increasing the effective thickness of the original paper.
  • the material must be insoluble in the liquid dielectrics commonly used to impregnate paper insulation, such as chlorinated biphenyls, mineral oil, etc.; it must not itself cause an intolerable increase in the dielectric loss factor of the paper; and it must be substantially free of alkali metals, because the presence of such metals increases the power factor of the paper.
  • the film-forming material must be one which is insoluble in water within one temperature range but which dissolves within some different temperature range.
  • both of these temperature ranges preferably lie below l0OC but this is not essential.
  • insoluble we mean that the material must not become highly swollen (gelatinized) or tacky, but it must be permeable to water so that diffusion of ions from the solid into the water phase can take place.
  • Materials having this critical characteristic permit the easy removal of alkali metals by simply washing them with water of low alkali metal content, maintaining the temperature within the range in which dissolution cannot occur. The efficiency of the washing process is improved by adding very small amounts of harmless cations, such as hydrogen ions or alkaline earth ions, to the wash water.
  • the washing can be carried out by any of a number of well established processes for washing finely divided solids, such as repeated batchwise dispersing, settling, and decantation; continuous washing and centrifugal decantation; and counter-current washing with rotary filters. Whatever the technique, extraction must be continued until the alkali metal content of the filmforming material, which will typically be about 1,000 parts per million before washing, has been reduced to no more than about 200 parts per million, and preferably, to no more than about 20 parts per million.
  • the material After washing has been completed, at a temperature at which insolubility of the material is maintained, the material is then dispersed in the desired quantity of water which is substantially free of alkali metals and the temperature is then raised or lowered, as the case may be, to a point within the range where solubility occurs. After dissolution is complete, any required adjustment of the concentration and final temperature is made, and the solution is ready to be used in the manufacture of our improved paper.
  • methyl cellulose starch
  • polyvinyl alcohol polyvinyl alcohol
  • protein polyvinyl alcohol
  • Methyl esters of cellulose are manufactured in the US. by Dow Chemical Company under the trademark Methocel.” These products are derived from either cotton linters or woodpulp and are available in wide ranges of viscosity and degree of methoxylation. We prefer grades having viscosities between 10 and 25 centipoise (2 percent aqueous solution, 20C) and a degree of substitution between 1.64 and 1.92. This type of methyl cellulose is insoluble in organic solvents and has the unusual property of being insoluble in hot water but readily soluble in cold water. Accordingly, the washing process with this material is carried out at a temperature of about 80C, and the slurry of washed methyl cellulose is then chilled to C in order to obtain a gel-free solution. After the methyl cellulose has dissolved, solubility is retained if the solution temperature is increased, up to about 35C, and the viscosity of the solution is reduced. The optimal temperature for application to the paper is about 30C.
  • the starches we find most useful are the oxidized and the chemically substituted types, such as hydroxyethylated starch, acetylated starch, etc., which are commonly used as surface sizes and coating binders in the manufacture of printing and writing papers. Enzyme converted pearl starches can also be used, but they are less convenient and the rheology of their solutions is less desirable than that of the chemically modified starches.
  • These starches are usually derived from corn but are also made from potatoes, milo, tapioca, etc.
  • the optimal temperature for application can be anywhere between about 30C and 90C, depending upon the solution concentration and the viscosity of the starch.
  • Polyvinyl alcohol is available in types which are soluble in water over the whole temperature range between 0C and 100C, but the type which we employ is the socalled fully hydrolyzed which has about 98 percent or more of the original acetyl groups removed by hydrolysis.
  • This type of polyvinyl alcohol is similar to starch in its solubility characteristics, i.e., it is insoluble in water at moderate temperatures but dissolves on cooking at 80C, depending upon the molecular weight and the number of residual acetyl groups.
  • Protein for use in our improved paper dielectric can be derived from any source provided that it is in a form which shows the solubility behaviour required for washing.
  • the product which we prefer is purified soya protein, commonly known as alpha protein.”
  • the low viscosity version of this material is the most suitable.
  • protein requires the addition of ammonium hydroxide to a pH .of about 8 9, as well as heating to about 50C or higher in order to obtain solubility.
  • Methyl cellulose in addition to increasing the electric strength of paper, has a unique ability to suppress corona discharge and to prolong the life of paper dielectrics under conditions of elevated temperature and high electrical stress.
  • the improved performance of capacitors made with a methyl cellulose treated paper dielectric will be discussed below.
  • the water soluble, film-forming material can be applied to the paper by any of the commonly used techniques of coating or surface-treating paper, such as size press coating, blade coating, roll coating, air knife coating, etc. It may be applied either on or off the papermachine, although we prefer the former for reasons of economy.
  • the coating material may be applied to only one side of the paper, or to both sides. Generally, treatment of both sides is preferred in order to maximize the effect of the treatment and to avoid curl problems. However, in specific instances, as in the preparation of capacitor paper for vacuum metallizing, it is advantageous to apply a heavy treatment to one side of the paper only in order to maximize smoothing of the surface to be metallized. leaving the other side toothy to permit easy penetration of liquid impregnants into the capacitor winding.
  • the amount of surface treatment which is required to provide significant improvement of electric strength is at least about 2 percent, on a dry weight basis, of the total weight of the treated paper.
  • the maximum amount which can be applied is limited only by the mechanics of application and drying, but we do not find it advantageous or practical to apply amounts greater than about 15 percent of the total weight of the treated paper, and the preferred range is from about 3 percent to about 10 percent.
  • Methyl cellulose having a degree of substitution of 1.64 to 1.92 was washed by the process previously described until its sodium content was reduced to 12 parts per million. It was then dissolved in water to form a 4% by weight solution by cooling to 5C. This solution had a viscosity of about cps at 20C. The solution was applied to a web fo capacitor tissue by means of a conventional size press located on the papermachine. The basis weight of the resulting treated paper product was adjusted to obtain the same weight obtained prior to the application of the methyl cellulose solution. Both the treated and untreated papers were supercalendered to a thickness of 0.5 mil and a density of 1.0 gm/cc.
  • the regular capacitor tissue which had a basis weight of 5.3 lbs/2000 ft and a thickness of 0.51 mils had a dielectric strength of 1540 volts/mil when tested according to ASTM D202-70.
  • the treated paper having a dry basis weight of 5.3 lbs/2000 ft of which 3.8 percent was methyl cellulose, and a thickness of 0.50 mils, had a dielectric strength of 1,850 volts/mil.
  • EXAMPLE ll Treated paper was produced as described in Example 1 except that a 3.8 percent by weight solution of methyl cellulose was used to coat a paper which, after supercalendering, had a thickness of 0.4 mils.
  • the paper produced prior to coating had a basis weight of 4.2 lbs/2,000 ft a thickness of 0.4l mils and a dielectric strength of 1,770 volts/mil.
  • the coated paper also having a basis weight of 4.2 lbs/2,000 ft of which 3.7 percent was methyl cellulose and a thickness of 0.40 mils, had a dielectric strength of 2,080 volts/mil.
  • the coated and uncoated papers were also used to construct conventional askarel-impregnated 5.0 [.LF capacitors which were stressed to failure with DC voltage.
  • Each capacitor was made by winding metal foil electrodes interleaved with paper, placing the wound body in an enclosure, and evacuating the enclosure and filling it with askarel.
  • the capacitors made with the regular, untreated paper showed an average breakdown voltage of 1,690 volts DC while the units made from the treated paper showed an average breakdown voltage of 2,140 volts DC.
  • EXAMPLE Ill Treated paper was produced as described in Example 1 except that a hydroxyethylated starch was prepared by washing to a sodium content of parts per million by the method previously described and then dissolved in water by heating to 90C for 30 minutes to produce an 8 percent by weight solution.
  • the temperature of the solution was adjusted to 50C before application to the paper, at which temperature the viscosity was 65 centipoise.
  • the paper produced prior to application of the starch solution was found to have a basis weight of 4.0 lbs/2,000 ft and a thickness of 0.4 mils and a dielectric strength of 1,520 volts/mil.
  • the treated paper had a dry basis weight of 4.1 lbs/2,000 ft*, of which 7.8 percent was starch, a thickness of 0.4 mils, and a dielectric strength of 2,030 volts/mil.
  • EXAMPLE 1V Treated paper was produced as described in Example I using hydroxyethylated starch as described in Example Ill.
  • the paper produced prior to the application of this solution had a basis weight of 5.0 lbs/2,000 ft, a thickness of 0.5 mils, and a dielectric strength of 1,365 volts/mil.
  • the treated paper had a dry basis weight of 5.1 lbs/2,000 ft, of which 7.7 percent was starch, a thickness of 0.5 mils, and a dielectric strength of l 855 volts/mil.
  • EXAMPLE V Treated paper was produced as described in Example 1 except that a 7 percent by weight solution of alpha protein was used. This 7 percent solution was prepared as described previously by washing to a sodium content of 14 parts per million and then using ammonium hydroxide to bring the solution to a pH of 8 9 and heating to 60C. The paper made prior to the application of this solution was found to have a basis weight of 4.1 lbs/2,000 ft and a thickness of 0.42 mils, and had a dielectric strength of 1,620 volts/mil. The treated paper had a dry basis weight of 4.1 lbs/2,000 ft of which 6.5 percent was protein, a thickness of 0.42 mils, and a dielectric strength of 1,960 volts/mil.
  • EXAMPLE V1 Regular capacitor tissue was treated using an offmachine roll coater and a solution of fully hydrolyzed polyvinyl alcohol.
  • the solutuon was previously prepared by washing to a sodium content of 8 parts per million and heating to C.
  • the resulting solution had a viscosity of 35 cps (20C), and a concentration of 3.9 percent by weight solids.
  • the untreated paper had a dry basis weight of 4.3 lbs/2,000 for a thickness of 0.5 mils, and a dielectric strength of 1,780 volts/mil.
  • the treated paper carried 1.8 percent polyvinyl alcohol, had a thickness of 0.5 mils, and had a dielectric strength of 1,950 volts/mil.
  • the basis weight and thickness of the coated paper wsa substantially the same as the basis weight and thickness of the uncoated sample. Nevertheless, the dielectric strength of the coated samples was, in each case, higher than the dielectric strength of the uncoated sheets. From this it follows that if coated and uncoated sheets having the same dielectric strength were produced, the coated sheets would be thinner than the uncoated sheets.
  • EXAMPLE VII Treated paper was produced using a 15 percent solution of acetylated starch prepared as described in Example lll. This solution was heated to 50 C and then applied at the size press of the paper machine to capacitor paper being produced having a basis weight of 4.15 lbs/2,000 ft The basis weight of the resulting treated productwas 4.61 lbs/2,000 ft'-. After producing a quantity of treated paper, the starch solution was discontinued and the amount of cellulose fiber in the sheet was increased, resulting in a basis weight of 4.60 lbs/2,000 ft? The three resulting capacitor papers were supercalendered, and tested as described in Example 1 except that two thicknesses of each paper were stressed to failure using increasing AC voltage.
  • the original paper having a basis weight of 4.15 lbs/2,000 ft and a thickness of 0.4 mils, had an average breakdown voltage (two sheets) of 1,285 volts AC.
  • the treated paper had a basis weight of 4.61 lbs/2,000 ft of which 13 percent was starch, a thickness of 0.45 mils, and an average breakdown of 1,850 volts AC. This represents, as compared to the original paper, a 44 percent increase in breakdown strength for a 13 percent increase in basis weight.
  • the final paper had a basis weight of 4.65 lbs/2,000 ft all of which was cellulose fiber, a thickness of 0.45 mils, and an average breakdown strength of 1,450 volts AC. This represents as compared to the original paper, a 13 percent increase in breakdown voltage for a 12 percent increase in basis weight.
  • EXAMPLE VIII Treated paper was produced using a 4 percent solution of methyl cellulose as described in Example I.
  • the solution of methyl cellulose was applied to capacitor paper being made having a basis weight of 3.65 lbs/2,000 ft".
  • the basis weight of the treated paper was 3.8 lbs/2,000 ft
  • the treatment was discontinued and the amount of cellulose fiber was increased to bring the basis weight to 3.8 lbs/2,000 ft
  • the three papers produced were supercalendered, and the electrical breakdown strength of two thicknesses of each paper was determined with AC voltage.
  • the treated paper had a basis weight of 3.8 lbs, a thickness of 0.36 mils, and an average breakdown of 1,270 volts. This represents as compared to the original paper, a 23 percent increase in breakdown strength for a 4 percent increase in basis weight.
  • the third paper had a basis weight of 3.8 lbs., all of which was cellulose fiber, a thickness of 0.36 mils, and an average breakdown strength of 1,080 volts. This represents, as compared to the original paper, a percent increase in breakdown voltage for a 4 percent increase in basis weight.
  • FIG. 1 shows the electrical breakdown strengths of untreated insulating paper and such paper treated according to the invention
  • FIG. 2 shows the life relationship between capacitors made with both treated and untreated papers
  • FIG. 3 shows the dissipation factors of treated and untreated papers
  • FIG. 4 shows the corona resistance of capacitors made with untreated paper and those made with paper coated with methyl cellulose.
  • FIG. 1 indicates the electrical breakdown strengths of pairs of sheets of capacitor tissues with thicknesses ranging from 03 mils to 0.5 mils.
  • Curve I plots electrical strength against thickness for conventional paper, and Curve II shows the same relationship for our paper coated with a 4 percent by weight solution of methyl cellulose.
  • the breakdown tests were run with 60 cycle AC. voltage, using the apparatus specified in A.S.T.M. Dl4964.
  • FIG 2 illustrates graphically the ability of the treated papers described herein to resist the degrading effects of high electrical stress.
  • Conventional 0.5 ;LF capacitors were constructed each using two thicknesses of capacitor paper as the dielectric. Three different capacitor papers were employed. Two of the papers selected were regular capacitor tissue of excellent commercial quality, while the third paper was treated by the process described in the examples using a 4 percent by weight methyl cellulose solution.
  • the capacitors were simultaneously impregnated with unmodified askarel in a common vessel using well established practices. After impregnation the units were wired to receive electrical stress and placed in a protective enclosure for life testing. All units were stressed simultaneously at 800 volts AC and allowed to remain so until all units had failed. The times to failure were noted for all units and are shown in FIG. 2.
  • FIG. 3 illustrates the effect of the treatments described above in the examples on the dissipation factor of dry papers.
  • Superimposed curves numbered I, II, and III represent typical values found with capacitor papers treated with 4 percent methyl cellulose solution, 8 percent starch solution, and untreated capacitor papers.
  • Superimposed curves IV and V represent values experienced with capacitor papers treated with solutions of 3.8 percent polyvinyl alcohol and 7 percent alpha protein. Note that surface coating according to the invention with methyl cellulose and starch have no effect on dissipation factor.
  • FIG. 4 illustrates the unique ability of papers treated with methyl cellulose to suppress corona discharges in capacitors when subjected to high voltages.
  • curves I, II and III illustrate the effect of electrical stress on the dissipation factor of regular capacitor papers, absorbent additive capacitor papers, and methyl cellulose treated papers, respectively.
  • Curve I shows the typical stress dependence of the dissipation factor of capacitors.
  • the initially high dissipation factor values are due to movements of ionic impu rities found in small amounts in the impregnating liquid phase of the capacitors when AC stress is applied. As stress is increased, the rate of motion of the ionic movements is increased and the resulting dissipation factor is lower.
  • Curve I in FIG. 4 shows the lowest value of dissipation factor for capacitors made with conventional capacitor papers to occur in the range of 300 to 400 volts/mil.
  • Curve II representing the newer, commercially used additive capacitor papers manufactured in accordance with US. Pat. Nos. 3.090,705; 3,480,847; and 3,555,377. These papers are conventional capacitor papers in which have been incorporated small percentages of finely divided mineral adsorbents. These materials have the desirable effect of scavenging and holding by adsorptive forces the previously mentioned ionic impurities from the liquid dielectric, thus removing them from the liquid phase of a capacitor and immobilizing them when low A.C. stress is applied. This accounts for the flat shape of Curve II. However, this beneficial scavenging effect does not prevent electrical discharges from occurring as stresses above 400 volts/mil are encountered. Thus, while the dissipation factor of capacitors made with additive papers is not stress dependent in the low stress range, and even though a cleaning of the liquid phase of a capacitor is observed, there is little evidence that the additive papers can be expected to resist corona discharges.
  • Curve III illustrates the effect of electrical stress on the dissipation factor of capacitors made using our methyl cellulose treated paper. Note that from a slightly higher initial dissipation factor value, the curve drops rapidly to its lowest dissipation factor value at about 300 volts/mil. Increasing stress up to 500 volts/- mil does not cause an increase in dissipation factor and then only slightly up to extreme stresses of 800 volts/- mi] and above.
  • Electrical insulating paper bearing a surface coating of a material insoluble in liquid dielectrics, such as chlorinated biphenyls and mineral oil, and being substantially free of alkali metals, said coating material being insoluble in water within one temperature range but soluble in water within a different temperature range, and said coating material being present to the extent of between 2 and percent of the total weight of the coated paper, said coated paper being thinner than otherwise identical uncoated paper having the same dielectric strength, and said coated paper having a percentage increase in dielectric strength greater than the percentage increase in its weight due to the presence of the coating.
  • a material insoluble in liquid dielectrics such as chlorinated biphenyls and mineral oil
  • a method of making electrical insulating paper comprising the steps of a. providing a material insoluble in liquid dielectrics, such as chlorinated biphenyls and mineral oil, said material being soluble in water within a first temperature range but insoluble in water within a second temperature range,
  • a method as defined in claim 16 including adding cations to the wash water of step (b).
  • washing step (b) is carried on until the alkali metal content of the material has been reduced to no more than 200 parts per million.
  • washing step (b) is carried on until the alkali metal content of the material has been reduced to no more than 20 parts per million.

Landscapes

  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Paper (AREA)
  • Organic Insulating Materials (AREA)
  • Fixed Capacitors And Capacitor Manufacturing Machines (AREA)
  • Manufacture Of Macromolecular Shaped Articles (AREA)
US13106071 1971-04-05 1971-04-05 Coated electrical insulating paper and method of making it Expired - Lifetime US3903352A (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
US13106071 US3903352A (en) 1971-04-05 1971-04-05 Coated electrical insulating paper and method of making it
GB29472A GB1381331A (en) 1971-04-05 1972-01-04 Coated electrical insulating paper and method of making it
DE2202436A DE2202436C2 (de) 1971-04-05 1972-01-19 Verfahren zum Herstellen von Isolierpapier
JP1131772A JPS5522886B1 (enExample) 1971-04-05 1972-01-31
FR7204317A FR2131954B1 (enExample) 1971-04-05 1972-02-09
FI746/72A FI58703C (fi) 1971-04-05 1972-03-20 Ytbelagt elektriskt isolerande papper och foerfarande foer dess framstaellning
IT2281272A IT955154B (it) 1971-04-05 1972-04-01 Carta per isolamento elettrico

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US13106071 US3903352A (en) 1971-04-05 1971-04-05 Coated electrical insulating paper and method of making it

Publications (1)

Publication Number Publication Date
US3903352A true US3903352A (en) 1975-09-02

Family

ID=22447670

Family Applications (1)

Application Number Title Priority Date Filing Date
US13106071 Expired - Lifetime US3903352A (en) 1971-04-05 1971-04-05 Coated electrical insulating paper and method of making it

Country Status (7)

Country Link
US (1) US3903352A (enExample)
JP (1) JPS5522886B1 (enExample)
DE (1) DE2202436C2 (enExample)
FI (1) FI58703C (enExample)
FR (1) FR2131954B1 (enExample)
GB (1) GB1381331A (enExample)
IT (1) IT955154B (enExample)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4218580A (en) * 1976-03-31 1980-08-19 Northern Telecom Limited Paper pulp insulated cable and method of manufacture
US4407697A (en) * 1982-04-05 1983-10-04 Mcgraw-Edison Company Process for making electrical insulating paper and the product thereof
US6309938B1 (en) 1997-04-28 2001-10-30 Agere Systems Guardian Corp. Deuterated bipolar transistor and method of manufacture thereof
US20030226649A1 (en) * 2002-06-07 2003-12-11 Kinsley Homan B. Low water paper
WO2015113012A1 (en) * 2014-01-27 2015-07-30 3M Innovative Properties Company Electrical insulation material and transformer
WO2015113013A1 (en) * 2014-01-27 2015-07-30 3M Innovative Properties Company Electrically insulating material and conductor wrap for electrical equipment, such as transformers

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1733524A (en) * 1926-11-08 1929-10-29 Champion Coated Paper Company Coating paper
US2045468A (en) * 1934-10-27 1936-06-23 Wilmington Fibre Specialty Com Insulating composition
US2178365A (en) * 1936-02-19 1939-10-31 Bell Telephone Labor Inc Electric conductor
US2502782A (en) * 1947-03-10 1950-04-04 Erickson Donald Robert Method of coating paper
US2526330A (en) * 1946-03-01 1950-10-17 Gen Electric Cellulose acetate coated dielectric paper for electrical devices
US2642420A (en) * 1948-07-02 1953-06-16 Eastman Kodak Co Preparation of polyvinyl alcohol
US2712539A (en) * 1953-04-28 1955-07-05 Buckeye Cotton Oil Company Method of manufacturing soybean protein
US2926088A (en) * 1955-02-08 1960-02-23 Phillip P Spiselman Method of brewing coffee
US2993949A (en) * 1956-10-08 1961-07-25 Minnesota Mining & Mfg Electrical insulating tape and article formed therewith
US3067141A (en) * 1960-11-07 1962-12-04 American Cyanamid Co Dielectric plastic composition
US3582513A (en) * 1968-02-09 1971-06-01 Borden Inc High viscosity polyvinyl alcohol from high-solids,low-viscosity conditioned polyvinyl ester solutions

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE767595C (de) * 1936-08-25 1952-11-24 Bosch Gmbh Robert Verfahren zur Herstellung metallisierter dielektrischer Stoffe, insbesondere Papier, fuer die Herstellung von sogenannten selbst-ausheilenden Kondensatoren, deren Metallbelag durch ein Vakuum-verfahren aufgebracht wird
DE866357C (de) * 1941-10-26 1953-02-09 Bosch Gmbh Robert Verfahren zur Herstellung von Isolierpapier, insbesondere fuer selbstausheilende elektrische Kondensatoren

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1733524A (en) * 1926-11-08 1929-10-29 Champion Coated Paper Company Coating paper
US2045468A (en) * 1934-10-27 1936-06-23 Wilmington Fibre Specialty Com Insulating composition
US2178365A (en) * 1936-02-19 1939-10-31 Bell Telephone Labor Inc Electric conductor
US2526330A (en) * 1946-03-01 1950-10-17 Gen Electric Cellulose acetate coated dielectric paper for electrical devices
US2502782A (en) * 1947-03-10 1950-04-04 Erickson Donald Robert Method of coating paper
US2642420A (en) * 1948-07-02 1953-06-16 Eastman Kodak Co Preparation of polyvinyl alcohol
US2712539A (en) * 1953-04-28 1955-07-05 Buckeye Cotton Oil Company Method of manufacturing soybean protein
US2926088A (en) * 1955-02-08 1960-02-23 Phillip P Spiselman Method of brewing coffee
US2993949A (en) * 1956-10-08 1961-07-25 Minnesota Mining & Mfg Electrical insulating tape and article formed therewith
US3067141A (en) * 1960-11-07 1962-12-04 American Cyanamid Co Dielectric plastic composition
US3582513A (en) * 1968-02-09 1971-06-01 Borden Inc High viscosity polyvinyl alcohol from high-solids,low-viscosity conditioned polyvinyl ester solutions

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4218580A (en) * 1976-03-31 1980-08-19 Northern Telecom Limited Paper pulp insulated cable and method of manufacture
US4407697A (en) * 1982-04-05 1983-10-04 Mcgraw-Edison Company Process for making electrical insulating paper and the product thereof
US6309938B1 (en) 1997-04-28 2001-10-30 Agere Systems Guardian Corp. Deuterated bipolar transistor and method of manufacture thereof
US20030226649A1 (en) * 2002-06-07 2003-12-11 Kinsley Homan B. Low water paper
WO2015113012A1 (en) * 2014-01-27 2015-07-30 3M Innovative Properties Company Electrical insulation material and transformer
WO2015113013A1 (en) * 2014-01-27 2015-07-30 3M Innovative Properties Company Electrically insulating material and conductor wrap for electrical equipment, such as transformers
CN105934800A (zh) * 2014-01-27 2016-09-07 3M创新有限公司 用于电气设备诸如变压器的电绝缘材料和导体带匝
CN105934801A (zh) * 2014-01-27 2016-09-07 3M创新有限公司 电绝缘材料和变压器
EP3100281A4 (en) * 2014-01-27 2017-11-15 3M Innovative Properties Company Electrically insulating material and conductor wrap for electrical equipment, such as transformers

Also Published As

Publication number Publication date
GB1381331A (en) 1975-01-22
FR2131954B1 (enExample) 1976-10-29
FI58703B (fi) 1980-11-28
FR2131954A1 (enExample) 1972-11-17
FI58703C (fi) 1981-03-10
DE2202436C2 (de) 1982-08-12
JPS5522886B1 (enExample) 1980-06-19
IT955154B (it) 1973-09-29
DE2202436A1 (de) 1972-10-12

Similar Documents

Publication Publication Date Title
EP4146866B1 (en) Coated paper substrate suitable for metallization
CN111519466A (zh) 一种不含氟碳化合物且可生物降解的防油纸及其制备方法
US3903352A (en) Coated electrical insulating paper and method of making it
EP0404582B1 (en) Gellan gum sizing
US2535690A (en) Fibrous dielectric compositions
JP2023500041A (ja) 表面コーティングされたセルロース系フィルム
US4467010A (en) Oil-impregnated polyolefin film for electric insulation and manufacturing method for the same
US3494826A (en) Polymer bonded cellulose and its preparation
EP3541865A1 (en) Method for making a film comprising mfc
US3157518A (en) Coatings of cellulose crystallite aggregates
US2971877A (en) Synthetic fiber paper and process for producing the same
US4196044A (en) Product and process for making a creped and calendered cellulosic electrical paper
SE539535C2 (sv) Förfarande för avvattning av en suspension innefattande mikrofibrillerad cellulosa
EP0470871B1 (en) Additive for paper and its use
EP4058631B1 (en) Method of producing a sheet comprising chemically modified cellulose fibres
Zhang et al. Different kinds of microfibrillated cellulose as coating layers providing fiber-based barrier properties
WO2021094440A1 (en) Crosslinked mfc
JPS5816B2 (ja) セイデンキロクタイ
WO2023103093A1 (zh) 一种含羧甲基改性纤维素纳米纤维的水性涂料制备方法及应用
US5158647A (en) Capacitor papers of flash-spun synthetic pulp fibers
US2257576A (en) Art of making vulcanized fiber
US3429819A (en) Thermally stable cellulosic insulation material
US2232041A (en) Electrical insulating material
US2038378A (en) Electrical insulation material
US2042588A (en) Cellulose structure