Classifications

• • 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
  • D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
  • D21H11/02—Chemical or chemomechanical or chemothermomechanical pulp
  • D21H11/04—Kraft or sulfate pulp
• • 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
  • D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
  • D21H11/16—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only modified by a particular after-treatment
  • D21H11/20—Chemically or biochemically modified fibres
• • 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
  • D21H5/00—Special paper or cardboard not otherwise provided for
  • D21H5/12—Special paper or cardboard not otherwise provided for characterised by the use of special fibrous materials
  • D21H5/14—Special paper or cardboard not otherwise provided for characterised by the use of special fibrous materials of cellulose fibres only
  • D21H5/141—Special paper or cardboard not otherwise provided for characterised by the use of special fibrous materials of cellulose fibres only of fibrous cellulose derivatives
  • D21H5/143—Special paper or cardboard not otherwise provided for characterised by the use of special fibrous materials of cellulose fibres only of fibrous cellulose derivatives grafted or encapsulated cellulose
• • 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

Definitions

• the process comprises the steps of preparing a graft-cellulose solution, or a mixed solution or suspension consisting of a synthetic polymer mixed into a cellulose solution or a graft-cellulose solution, solidifying the solution, mixed solution, or suspension into a regenerating substance such as air or a precipitant, forming the regenerated substance thus solidified into a pulplike substance adapted to be fabricated into a paper, and forming the pulplike substance only or the pulplike substance mixed with the ordinary beaten pulp into an insulating paper.
• This invention relates to a process for the production of an electric insulating paper and also to the insulating paper itself, which has a far lower dielectric constant and dielectric loss tangent (tan 8), a higher dielectric strength, and superior oil resistance and heat resistance than conventional electric insulating papers.
• electric insulating materials of far lower dielectric constants and dielectric loss tangents, of higher dielectric strengths, and of superior oil resistance and heat resistance, and having structures easily impregnated with insulating oil are required for their construction. Furthermore, the above-mentioned features of the insulating materials must be maintained for long periods. For instance, in an extrahigh voltage cable of 500 kv., it is considered essential that the dielectric constant be lower than 3.0 and the dielectric loss tangent (tan 8) be less than 0.1 percent (under the condition of 80 C., oil filled, and with the application of IO kv./mm.).
• deionized insulating paper has been employed in a 275 kv. transmission cable.
• a transmission cable of avoltage of 500 kv. or more and when the cable is employed as a long distance line, even the dielectric constant and the dielectric loss tangent of the deionized insulating paper are still too large, resulting in the disadvantage that the transmission capacity of the cable is considerably decreased by use of such insulating paper.
• the insulating paper according to the present invention is characterized in that the synthetic polymer and the cellulose are coupled or connected at a molecular level. More specifically, novel organic solvent capable of dissolving the cellulose is employed and the thus-obtained solution is added to another solution containing the synthetic polymer for blending the cellulose together with the synthetic polymer. By regeneratively solidifying the solution thus blended in a precipitant, a mixed product of the cellulose and the synthetic polymer can be obtained.
• a pulplike substance When the product is beaten and made into a fibrillic substance, a pulplike substance can be obtained, and when this pulplike substance is added to the required amount of beaten pulp and made into paper, a product having a paperlike structure and a porous nature and wherein the synthetic polymer and the cellulose are mixed in a molecular level can be obtained.
• the electric insulating paper of this invention Comparing the electric insulating paper thus obtained with the conventional electric insulating paper, the electric insulating paper of this invention has a far lower dielectric constant, a lower dielectric loss tangent, a high dielectric strength, and sufficient oil passages due to its porous nature than the conventional paper. Furthermore, the mechanical characteristics, such as tensile strength, elongation, tearing strength, and Youngs coefficient, is equivalent or slightly higher than those of conventional insulating paper.
• the insulating paper according to the present invention since the synthetic polymer and the cellulose are mixed on a microscopic molecular level, the cracking and crazing caused in the conventional plastic films are not created therein, and the advantageous features of having a sufficient oil resistance, facility in making into paper in comparison with the conventional construction wherein particles or fibers of the synthetic polymer are mixed together, a high density and air tightness, and a superior dielectric strength are thereby achieved. Furthermore, in the novel insulating paper, the heat resistance of the synthetic polymer is utilized, so that a cable employing the insulating paper can endure higher temperatures than conventional insulating papers and can be used for a longer period than the conventional insulating paper.
• a suitable synthetic polymer which is insoluble in organic solvents but has a superior electric nature for example, crosslinked polyethylene, polytetrafluoroethylene, or polypropylene, is added in the form of fine particles into the cellulose solution so that the synthetic polymer and the cellulose are blended together.
• the mixed solution may be solidified thereafter in a fibrous or granular configuration. In this way, the fine particles of the synthetic polymer are incorporated within 'the cellulose in such a manner.
• the synthetic polymer is enveloped by the cellulose, and the insulating paper, obtained from the fibrous or granular substance subsequently being made into paper together with the beaten pulp, has equivalent characteristics to that obtained by the above-described procedure wherein the synthetic polymer is blended in its liquid state. That is, the insulating paper thus obtained has a far superior heat resistance, oil resistance, and a more stable nature than the conventional insulating paper made of synthetic fibers or of synthetic polymer fibers.
• the method according to the present invention utilizes an organic solvent for dissolving the .cellulose, so that the blending of cellulose with the synthetic polymer can be facilitated.
• the mixture thus blended does not include any metallic ions which deleteriously affect the dielectric loss tangent.
• an aliphatic primary, secondary, or tertiary amine, or an alicyclic secondary amine for example, isobutylamine, secondary butylamine, tertiary butylamine, dimethylamine, diethylamine, trimethylamine, triethylamine, piperidine, or pyrolydone is advantageously employed.
• an organic solvent following substances can be employed:
• Cellulose is added to any one of the above-described solvents so that the cellulose is dispersed in a slurrylike manner in the solvent, and more than 3 mols of an amine and sulfurous acid anhydride respectively for each glucose residue are added so that the cellulose is dissolved.
• Organicsolventsnot including an active hydrogen such as N,N-dimethylformamide, N,N-diethylformamide, acetonitrile, propionitrile, diethylsulfoxide, N-methyl-Z- pyrrolidone, methyl formate,- ethyl formate, methyl acetate, ethyl acetate, n-butyl acetate, methyl propionate, cellosolve acetate, B-butyroloctone, nitromethane, nitroethane, nitrobenzene, 1,4-dioxane, tetrahydrofuran, pyridine, and the like can be employed, and any one of the above-described organic solvents is added to the cellulose so that the cellulose is thereby dispersed. More than 3 mols for each residue of glucose, of nitrogen dioxide as a liquid or a gas are added to the above-described solution so that the cellulose is thereby dissolved.
• Cellulose is dispersed into an organic solvent such as dimethylsulfoxide, diethylsulfoxide, N,N-dimethylformamide, N,N-dinethylacetamide, N-methyl-2-pyrrolidone, pyridine and the like, Nitrosyl chloride, more than 3 mols for each glucose residue, is added so that the cellulose is dissolved in the solvent.
• organic solvent such as dimethylsulfoxide, diethylsulfoxide, N,N-dimethylformamide, N,N-dinethylacetamide, N-methyl-2-pyrrolidone, pyridine and the like.
• Cellulose is dispersed into an organic solvent such as dimethylsulfoxide, N,N-dimethylformamide, N ,N dimethylacetamide, pyridine, N-methyl-2-pyrrolidone, and the like, and adding chloral anhydride of more than 5 mols per each glucose residue is added so that the cellulose is dissolved in the solvent.
• organic solvent such as dimethylsulfoxide, N,N-dimethylformamide, N ,N dimethylacetamide, pyridine, N-methyl-2-pyrrolidone, and the like
• All of the above-described methods for dissolving cellulose can be carried out generally at room temperature and at mospheric pressure, and the time period required for, the dissolution ranges from several minutes to several hours.
• Cellulose to be dissolved in the solvent can be selected from a group consisting of chemical woodpulp, cotton linter, depolymerized cellulose, and regenerated cellulose.
• any kind of cellulose not including any impurity for instance, nonbleached kraft-pulp, can be employed.
• a cellulose solution is produced firstly employing any one of the five methods described above, and, in this solution, one, two, or more types of synthetic polymers having low dielectric loss tangent are added as a liquid or as a fine powder, thus blending the cellulose with the synthetic polymer or polymers.
• the blended solution is thereafter extruded into air or into a precipitant for the blended solution so that a regenerative solidification thereof can be obtained.
• the following methods are suitable for the purpose of obtaining a pulplike substance or granules thereof to be made into paper from the mixed solidification of the cellulose and the synthetic polymer or polymers.
• the blended solution of cellulose and the synthetic polymer or polymers is spun into air or a liquid, employing a dry or wet method, and, after the spun solution is solidified, the solid material is then cut into short fibers. When these short'fibers are beaten, if it is required, and then fibrillated, the pulplike substance to be employed for producing insulating paper can be obtained.
• the blended solution is spun into air or into a precipitant from a predetermined height in a manner not exerting any elongating force, so that the spun substance is solidified into fibers.
• the fibers thus obtained are subsequently cut into a predetermined length and beaten, if it is required, so that the material is thereby fibrillated, and the pulplike substance to be used in insulating paper can be obtained.
• the graft-cellulose solution so that a mixed solution or suspension thereof is obtained, and from this solution or suspension the insulating paper can also be produced.
• Silicone Dlmethylsulfoxide do do do stance is split into a split-fiber, which is thereafter made into pulplike substance through a beating process, if it is required.
• the solidified substance is formed into any granular configuration such as globular, fiat, or any other shape.
• a water-soluble polymer for instance, methyl cellulose, or ethyl cellulose is further added for the purpose of promoting fibrillation, and after solidification, the water-soluble polymer can be removed by dissolving it during the beating process for fibrillating the solidified substance.
• the pulplike substance obtained from the blended solution of cellulose and a polymer in accordance with the above-described methods is in itself easily made into paper, if it is required, an ordinary beaten pulp can be further added to the above-described pulp-like or granular substance which is thereafter made into paper, so that the content of the synthetic polymer is about 20 to 80 weight percent of the paper, and, in this way, an electric insulating paper of superior electrical and mechanical characteristics can be obtained.
• the mixing methods of the cellulose and the synthetic polymer not only merely adding the synthetic polymer into the cellulose solution as described above, but also a method which comprises dispersing cellulose in slurry state into a synthetic polymer solution or a suspension thereof can be employed, and the synthetic polymer can be mixed with the cellulose.
• the synthetic polymer adapted to produce an insulating paper having a low dielectric loss tangent those having a low dielectric loss tangent and a high heat resistance are desirable.
• Such polymers can be selected from a group consisting of polycarbonates, polyphenyleneoxides, polysulfones, polystyrenes, cross-linked polyethylenes, polytetrafluorethylenes, polytrifluoroethylene chlorides, polypropylenes, polyacetals, poly-4-methylpentene-l polyvinylcarbazoles, polyesters, and polyfluoroethylenepropylene copolymers.
• the electric insulating paper of an advantageous quality can also be produced from a solution of graft cellulose.
• a solvent system employing an organic solvent soluble for grafted polymers is selected, which system is utilized with another solvent system (5) for cellulose for the purpose of dissolving graft-cellulose, and whereby a graft-cellulose solution can be obtained.
• styrenegraftcellulose, various kinds of vinyl monomer graft-celluloses, and silicone graft-cellulose can be dissolved, and from which solution, a pulplike or granular substance easily made into paper can be obtained.
• an electric insulating paper can also be produced from graft-cellulose which has been heretofore difficult to be processed with beating and which has been difficult to be made into paper.
• insulating paper of more than IOO-micron thickness is used from the practical point of view.
• insulating papers of a thickness equal or less than 50 microns exhibits better characteristics than those for the more than lOO-micron thickness.
• the measurements of the dielectric constants and dielectric loss tangents have been carried out under the conditions of a 10 kv./mm. electric field strength, 60 cps.
• the insulating paper is immersed with JlS class 1 oil, and impulse breakdown strength is measured at room temperature impregnated with 118 Class 1 oil (sheet test) also.
• the measured densities are the apparent values obtained at 20 C. and 65 percent R.H., and the gas air-tightness was measured by means of Oken Type airtightness measuring instrument.
• the conventional electric insulating paper which is made of pulp mixed with substances of better insulating characteristics has a structural construction in which the substances of better insulating characteristics are sandwiched between the pulp fibers, whereas the insulating paper according to the present invention has a construction in which the substance or substances of better insulating characteristics are involved in or enveloped by the cellulose fiber itself.
• EXAMPLE 1 Three parts of nonbleached kraft pulp for producing insulating paper are added into a mixed solution consisting of 50 parts of N,N-dimethylformamide and 50 parts of dioxane, and the mixed solution thus obtained has 6 parts of nitrogen dioxide added to it and stirred at room temperature under atmospheric pressure. After about 30 minutes of stirring, a cellulose solution of transparent, green-blue, and viscous nature is obtained. A solution consisting of three parts of a polysulfone, P-l700 Union Carbide C., and 15 parts of dioxane is further added to the cellulose solution and stirred, so that a transparent uniformly blended solution of cellulose and polysulfone is obtained.
• the blended solution is thereafter extruded through nozzles of 0.6 mm. diameter into air under a pressure of 2 kg./ cm and immediately thereafter the extruded solution is placed into water to be solidified, so that a blended substance between the cellulose and polysulfone having a fibrous shape can be obtained.
• the fibrous substance is cut into lengths of 3 mm. or less, washed with hot water for removing any remaining organic solvent, and subjected to a beating process using a beating machine, whereby a pulpl ike substance fibrilized as in the case of an ordinary pulp and beat-processed to about 50 SR can be obtained.
• the insulating paper according 5 to the present invention has a dielectric constant, a dielectric loss tangent, and an impulse breakdown characteristic which are far superior to those of the conventional insulating paper made of the nonbleached kraft pulp only.
• EXAMPLE 2 30 Thirty (30) parts of dimethylsulfoxide and 6 parts of diethylamine are added to 3 parts of nonbleached kraft pulp employed for producing insulating paper so that the kraft pulp is well mixed and swollen by these substances. The mixture is then blended with 5 parts of sulfurous acid anhydride in a liquid state and stirred for about 30 minutes at a room temperature. A cellulose of viscous, transparent, and yellowishbrown can be obtained. On the other hand, 3 parts of polyphenylenoxide, PPO 691-1 1 I made by the General Electric Co., is dissolved in 70 parts of chloroform, and the thus obtained solution is further mixed with three parts of diethylamine and one part of sulfurous acid anhydride.
• PPO 691-1 1 I made by the General Electric Co.
• the resultant polyphenylenoxide solution is thereafter added to the above prepared cellulose solution little by little and stirred thoroughly so that a blended solution of cellulose and polyphenylenoxide can be obtained.
• the blended solution is extruded through nozzles of 0.6 mm. diameter into air as described in example I and solidified in a regenerative bath consisting of water and methanol mixed at a ratio of 3:7 so that a fibrous substance is obtained.
• the fibrous substance is then cut into lengths less than 3 mm., washed with pure water, and beaten to obtain a fibrillated pulplike substance of 63 SR beating degree.
• the insulating paper according to this invention has a superior impulse breakdown strength and tensile strength in comparison with the paper wherein the granular polyphenylenoxide is simply mixed with the kraft pulp.
• EXAMPLE 3 Three parts of nonbleached kraft pulp for producing insulating paper is dispersed into a mixture consisting of 30 parts of formamide, parts of chloroform, and 10 parts of diethylamine, and thereafter bubbling into the solution eight parts of sulfurous acid anhydride in gas state, a cellulose solution of viscous, transparent, and yellowish-brown can be obtained.
• three parts of polysulfone is dissolved into 15 parts of chloroform, and the thus-obtained liquid is added to the above described cellulose solution so that a uniformly blended solution of cellulose and polysulfone is thereby obtained.
• the blended solution is extruded through nozzles of 06. mm.
• the insulating paper thus obtained has the characteristics shown in table lll.
• the solidifying speed of the mixture consisting of cellulose and polysulfone is found to be too fast, whereby the obtained fibers turned out to be too hard and too long of a period was required for beating.
• the blended solution of cellulose and polysulfone obtained as in example 3 is extruded through nozzles of 0.6 mm. diameter into water in a stationary state for solidification.
• solidified substance is thereafter placed into methanol for removing the remaining chloroform completely so that a fibrous substance is regenerated.
• the regenerated substance is then beaten. Since the substance now obtained can be more easily beaten, the beating degree can be raised to 70 SR.
• the pulplike substance thus obtained is made into paper employing the same preparation ratio as in example 3, an insulating paper of higher airtightness and impulse breakdown strength can be obtained.
• the test results are indicated in the following table IV.
• Example 4 Airtightness Ee'cI/I cc.) 3000 26,000 Impulse Breakdown Strength 1653 185.0 (km/mm.)
• EXAMPLE 5 A blended solution of cellulose and polysulfone prepared according to example 1 was extruded through a spinning nozzle having 30 holes of 70-micron diameter into water, and after the solution was solidified, the solidified fibers were elongated by about 250 percent and blended fibers of cellulose and polysufone were obtained. These fibers were cut to lengths less than 3 mm., beaten to about 70 SR of pulplike substance, and made into paper employing pure water. The insulating paper thus produced exhibited the characteristics shown in table 5.
• the remaining substance was dropped into methanol for completely removing the remaining dimethylsulfoxide, diethylamine, and methylene chloride, a fibrous substance could be obtained.
• the fibrous substance was then cut and beaten to 55 SR, and the resultant pulplike substance, 50 parts, was mixed with 50 parts of unbleached kraft pulp for insulating paper and of 88 SR beating degree and made into paper employing pure water.
• the thusobtained insulating paper exhibited the characteristics shown in table 6.
• EXAMPLE 7 Three parts of cotton linter was dispersed into 100 parts of dimethylsulfoxide, 12 parts of chloral anhydride was added thereto so that the cellulose was dissolved at room temperature into a cellulose solution colorless and transparent. This solution was further mixed with 12 parts of a denatured polyphenyloxide ground to less than 200 mesh, Noryl 731-802, made by the General Electric Co., so that a suspension of a cellulose solution was obtained. The suspension was therefore extruded through nozzles of 1.3 mm. diameter into water in a manner as described in example 1 for solidifying the cellulose. The solidified substance was then beaten by means of a Lumpen Mill so that a granular substance of from to 200 mesh was obtained.
• the pulplike substance was then made into paper employing pure water, pressed, and dried, and thereafter dipped into methylene chloride solution for about 10 seconds for dissolving one part of the polycarbonate and for strengthening the bonding force between fibers and also for raising air resistance thereof.
• the characteristics of the insulating paper thus obtained are indicated in table 8.
• EXAMPLE 9 One hundred parts of formamide and 6 parts of diethylamine were added to three parts of insulating paper use unbleached kraft pulp so that the pulp was thereby wetted and swollen. The thus-swollen pulp was further mixed with five parts of sulfurous acid anhydride in a liquid state so that the cellulose was dissolved. Three parts of electron beam irradiated cross-linked polyethylene , was then added to this solution and stirred well to obtain a suspension liquid thereof. The suspension thus obtained was then extruded through nozzles of 2.0 mm. diameter into water for solidifying the cellulose. The cellulose thus solidified was then cut into lengths less than 3 mm., ground by a Lumpen Mill into a granular substance of from 50 to 200 mesh.
• the short fibers were thereafter beaten to about 50 SR of a pulplike substance.
• Sixty parts of the pulplike substance was mixed with 40 parts of insulating paper use unbleached kraft pulp of 75 SR beating degree and was made into paper employing pure water.
• the insulating paper thus obtained exhibited characteristics as indicated in table 10.
• EXAMPLE 1 Twenty parts of cotton linter, 40 parts of styrene monomer, and 1000 parts of water containing ceric ammonium nitrate at a concentration of 2.7 x 10 3 mol/lliter were mixed, and the styrene was grafted by heating the mixture at 70 C. under a nitrogen gas flow. The reaction was continued for about 5 hours so that styrene graft-cellulose of 104 percent degree of grafting was obtained.
• EXAMPLE 12 In a manner similar to example 1 l, styrene was grafted to cotton lintcr so that styrene grafted cellulose of a graft ratio of 40 percent was thereby obtained. Five parts of this grafted cellulose and three parts of polysulfone were added to 100 parts of dioxane and dispersed well. The mixture thus obtained was further mixed with nitrogen dioxide so that the grafted cellulose was thereb'y dissolved and a blended solution of a styrenegrafted cellulose and polysulfone was simultaneously obtained. This blended solution was extruded through a nozzle having holes of 0.6 mm. diameter into water for solidification, and the solidified substance was then cut, beaten to about 65 SR, so that the thus-obtained pulplike substance was thereafter made into paper employing pure water. The insulating paper thus obtained has the characteristics shown in table 12.
• EXAMPLE l3 Sulfurous acid anhydride as a gas was cooled at 30 C. so that sulfurous acid in a liquid state could be collected in a pressure proof container, and three parts of polysulfone was added to 100 parts of thus-obtained liquefied sulfurous acid so that the polysulfone was thereby dissolved. Three parts of cotton linter and six parts of diethylamine were then added to the above-described liquefied solution, and by raising the temperature to a room temperature, the cellulose was dissolved. The thus-obtained mixed solution of cellulose and polysulfone was extruded through nozzles of 0.6 mm. diameter into methanol so that the mixture was solidified.
• a method of producing an electrical insulating paper comprising the steps of( l preparing a synthetic polymer cellulose liquid mixture by mixing a synthetic polymer with a member selected from the group consisting of a cellulose and a grafted cellulose solution; (2) extruding the thus-prepared liquid mixture into a medium for regenerating the polymer cellulose as a solid; (3) forming the regenerated polymer cellulose into a configuration adapted to be processed into a paper; and (4) processing the thus formed polymer cellulose into a paper of sheet form; said paper in a sheet form containing a synthetic polymer in a range offrom to 80 weight percent.
• step (3) is a granular configuration.
• the synthetic polymer cellulose liquid mixture is prepared using a solvent system selected from the group consisting of (a) a system consisting of an organic solvent, sulfurous acid anhydride, and an amine, selected from the group consisting of aliphatic primary amines, aliphatic secondary amines, aliphatic tertiary amines and alicyclic secondary amines, (b) a system consisting of an organic solvent, and nitrogen dioxide, (c) a system consisting of an organic solvent and nitrosyl chloride, (d) a system consisting of an organic solvent, and chloral anhydride, and (e) a system consisting of liquefied sulfurous acid and an amine selected from the group consisting of aliphatic primary amines, aliphatic secondary amines, aliphatic tertiary amines and alicyclic secondary amines.
• a solvent system selected from the group consisting of (a) a system consisting of an organic solvent, sulfurous acid anhydride, and
• said synthetic polymer is selected from a group consisting of a polycarbonate, a polyphenylenoxide, a polysulfone, a polystyrene, a crosslinked polyethylene, a polytetrafluoroethylene, a polytrifiuorochloroethylene, a polypropylene, a polyacetal, a poly-4-methyl pentane-l, a polyvinylcarbazole. a polyester, and a polyfluoroethylenepropylene copolymer.
• said graft cellulose is selected from the group consisting of a styrene grafted cellulose, a silicone-grafted cellulose, and a vinyl-grafted cellulose.
• An electric insulating paper having superior electrical characteristics produced by the steps (1) preparing a synthetic polymer cellulose liquid mixture by mixing a synthetic polymer with a member selected from the group consisting of a cellulose solution and a grafted cellulose solution; (2) extruding the thus prepared liquid mixture into a medium for regenerating the polymer cellulose as a solid; (3) forming the regenerated polymer cellulose into a configuration adapted to be processed into a paper; and (4) processing the thus formed polymer cellulose into a paper of sheet form; said paper in a sheet form containing a synthetic polymer in a range of from 20 to weight percent.
• said synthetic polymer is selected from the group consisting of a polycarbonate, a polyphenyleneoxide, a polysulfone, a polystyrene, a cross-linked polyethylene, polytetrafluoroethylene, a polytrifluorochloroethylene, polypropylene, a polyacetal, a poly-4-methylpentane-l, polyvinylcarbazole, a polyester, and polyfluoroethylenepropylene cop
• grafted cellulose is selected from the group consisting of a styrene-grafted cellulose, silicone-grafted cellulose, and a vinylgrafted cellulose.

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• 1969
  • 1969-02-12 JP JP44010246A patent/JPS491243B1/ja active Pending
• 1970
  • 1970-02-12 DE DE2006398A patent/DE2006398C3/de not_active Expired
  • 1970-02-12 US US11019A patent/US3617438A/en not_active Expired - Lifetime
  • 1970-02-12 GB GB691570A patent/GB1305452A/en not_active Expired
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