JP2008156782A - Paper consisting of polyarylene sulfide oxide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper of a polyarylene sulfide oxide (PPSO) having a high insulation property improved in dielectric breakdown strength, also excellent in heat resistance and chemical resistance as capable of being used for various electric insulation materials, and being infusible. <P>SOLUTION: This paper constituted by the PPSO and having a dielectric breakdown strength of ≥10 kV/mm and also a density of ≥0.50 g/cm<SP>3</SP>can be used as electric insulation paper used for covering various cables or electric wires, printed circuit boards, motors, transformers, or the like. In addition, since having the high electric insulation property, it enables the miniaturization of insulating layers of various devices using the electric insulation paper, and contributes to the improvement of their performance. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a paper made of polyarylene sulfide oxide (PPSO) having excellent heat resistance and chemical resistance and having high dielectric breakdown strength. The PPSO paper of the present invention can be used as an electrical insulating paper used in various cable and wire coatings, printed circuit boards, motors and transformers.

  PPSO obtained by oxidizing polyarylene sulfide (PPS) has excellent heat resistance, chemical resistance, especially acid resistance, and also has excellent characteristics that it does not melt by heat, compared to PPS. Studies are being made on utilization in various forms such as fiber, fabric, and paper.

  As a study on PPSO paper in particular, as proposed in Patent Document 1, the PPS is oxidized to PPSO, and then a sulfonic acid group is further introduced into the PPSO aryl group, resulting in high whiteness and flexibility. Sheets that are rich in water resistance and chemical resistance, have high chemical resistance and have ion exchange ability and are useful as various ion exchange papers have been obtained, but there is no indication about the use of paper made of PPSO as electrical insulating paper. Absent.

  Further, in Patent Document 2, paper is obtained using PPSO pulp obtained by beating PPSO fibers, but since the diameter of the fibers obtained by beating is thick, there are many voids between the fibers when the paper is used. Since it is formed, the breakdown strength is about 0.8 kV / mm, and a paper having a high breakdown strength has not been obtained.

  Similarly, in Patent Document 3, PPS paper composed of PPS fibers of normal fineness is oxidized to obtain PPSO paper. However, the strength of the dielectric breakdown of the paper obtained due to the large gap between the fibers is as follows. The limit was about 6.4 kV / mm.

  On the other hand, Patent Document 4 proposes to obtain PPSO paper by oxidizing paper made of PPS nanofibers. However, in this method, since paper is oxidized in the state of paper, the paper is treated in the processing step. Each PPS fiber constituting the shrinkage occurs, and the paper shrinks non-uniformly to form voids between the fibers. As a result, only PPSO paper with low dielectric breakdown strength is obtained. It was not done.

Thus, although PPSO paper has excellent heat resistance and chemical resistance, and has excellent properties of not being melted by heat, only the paper with low dielectric breakdown strength was obtained in the prior art. However, it could not be used practically as an electrical insulating material. On the other hand, with the demand for higher output and smaller size due to higher performance of various electronic devices, downsizing along with the heat resistance of the insulating layer in the device is a major issue, and the strength of dielectric breakdown of electrical insulating paper Thinning is required by improvement.
JP 63-152499 A (pages 13-14) JP 2006-225807 A (pages 19-20) JP 2006-16585 (pages 20-26) JP 2006-257618 A (page 15)

  An object of the present invention is to provide PPSO paper having excellent insulating properties with improved strength of dielectric breakdown, which has been a problem of the above-mentioned prior art, and can be used as various electrical insulating materials. The object is to provide PPSO paper that is excellent in chemical properties and infusible.

The above-described object of the present invention can be achieved by a paper having a dielectric breakdown strength of 10 kV / mm or more and a density of 0.50 g / cm ³ or more composed of polyarylene sulfide oxide.

  The PPSO paper of the present invention has high insulation breakdown strength in addition to excellent heat resistance, chemical resistance and infusibility, and has little variation and excellent insulation. It can be used as electrical insulating paper used in printed circuit boards, motors and transformers. In addition, since it has high electrical insulation properties, it is possible to make the insulation layers of various devices that use electrical insulation paper more compact and contribute to improving its performance.

  Hereinafter, the PPSO paper of the present invention will be described in detail.

PPSO in the present invention is
The following general formula (1)

(R ″ represents hydrogen, halogen, an aliphatic substituent substituted with any functional group within an allowable range of valence, or an aliphatic substituent substituted with an aromatic substituent; R ″ may be linked to each other to form a crosslinked structure. R ″ may be a polymer chain composed of PPSO. R ′ ″ represents a polymer chain composed of PPSO, and m is 0. Represents an integer of 1 to 3. X represents 0, 1, or 2), or the above repeating unit as a main structural unit, and the above repeating unit 1.0 mol or less per mol, preferably 0.3 mol or less of general formulas (2) to (8)

(R ″ represents any one of hydrogen, halogen, an aliphatic substituent substituted with an arbitrary functional group within an allowable range of valence, and an aliphatic substituent substituted with an aromatic substituent; `` '' Represents an aliphatic substituent substituted with an arbitrary functional group within an allowable range of valence, and R or R ′ between molecules may be linked to each other to form a crosslinked structure. R ″ and R ″ ″ may be a polymer chain composed of PPSO. R ′ ″ represents a polymer chain composed of PPSO, m represents an integer of 0 to 3, and n represents Represents an integer of 0 to 2, and X represents 0, 1, or 2). Moreover, among the repeating units represented by the general formula (1), the ratio of the structural units in which X is 1 or 2 in the structural units in which X is 0, 1, or 2 is 0.5 or more and 0.9. Or less, more preferably 0.7 or more and 0.9 or less.

  Further, the PPSO of the present invention has substantially no melting peak in the differential scanning calorimeter (DSC) measurement. Specifically, the fact that the melting peak is not substantially observed means that PPSO having a heat of fusion of 15 J / g or less, preferably 10 J / g or less, more preferably 5 J / g or less, particularly preferably 1 J / g or less. In this range, it has particularly excellent characteristics regarding heat resistance and chemical resistance. This is an important factor not only for maintaining sufficient strength even at high temperatures in the paper state, but also for preventing dielectric breakdown associated with pinholes caused by melting.

  Here, the DSC measurement conditions were as follows: a nitrogen flow rate of 20 mL / min and a differential scanning calorimeter (DSC manufactured by PerkinElmer Co., Ltd.), a sample amount of 5 mg to 10 mg, and a temperature program of 30 ° C. to 500 ° C. This is the heat of fusion when measured at a temperature of 30 ° C. (temperature increased from 30 ° C. to 340 ° C. at a temperature increase of 10 ° C./min).

  The strength of dielectric breakdown as used in the present invention is the same as that in Example F.1. It is a value obtained by the method described in the item. By setting it to 10 kV / mm or more, it becomes possible to develop the application of insulating paper used under high voltage such as a transformer or a motor. From the viewpoint of insulating reliability, the strength of dielectric breakdown is preferably 20 kV / mm or more, more preferably 30 kV / mm or more, and most preferably 40 kV / mm or more. There is no particular upper limit on the strength of dielectric breakdown, but the upper limit that can be reached at the present time is about 100 kV / mm.

The density referred to in the present invention means that of Example E.I. And the density of the paper of the present invention is 0.50 g / cm ³ or more. By setting the density to 0.50 g / cm ³ or more, voids between the fibers in the paper surface direction and the thickness direction of the paper are crushed, and friction between the fibers is increased, whereby the strength of the paper is improved and the handleability is improved. In addition, variations in the strength of dielectric breakdown are reduced. The density of the paper is preferably 0.70 g / cm ³ or more and 1.4 g / cm ³ or less, more preferably 0.80 g / cm for the purpose of improving strength, reducing variation in the strength of dielectric breakdown, and enabling resin impregnation. ³ or more and 1.3 g / cm ³ or less. In addition,
An important technique for obtaining a paper having an excellent dielectric breakdown strength and a high density as described above is to make a pre-oxidized PPSO, and the air permeability before pressing is 1.0 cc / cm ² / sec or less. The pressing is performed at a high temperature and a high pressure after obtaining a dense PPSO paper. By using paper having an air permeability of 1.0 cc / cm ² / sec or less, a slight gap between fibers can be crushed by pressing with a press, and the strength of dielectric breakdown is improved. Moreover, since the voids existing in the paper surface direction and the thickness direction of the paper are crushed by pressing under high temperature and high pressure, high density is achieved.

  PPSO is not easily deformed by heating because of its excellent heat resistance and infusibility, and the effect of improving the density of paper cannot be sufficiently obtained under the press temperature and pressure in the normal paper making process. Therefore, in order to improve the density of PPSO paper, it is necessary to press at a high temperature and particularly under a high pressure. For the purpose of facilitating deformation and reducing the thickness of the paper, the press temperature is preferably 200 ° C. or higher, more preferably 250 ° C. or higher. For the same purpose, the pressing pressure in a flat plate press is preferably 10 MPa or more, more preferably 20 MPa or more, and most preferably 50 MPa or more. In the calendar press, the press pressure is preferably 1 kN / cm or more, more preferably 10 kN / cm or more. The press time for the flat plate press is such that heat is transferred to the entire paper surface to enable deformation, and in order to avoid thermal deterioration of the paper, in the case of the flat plate press, it is 1 minute to less than 30 minutes, more preferably 3 minutes to less than 10 minutes. . The number of presses in the calendar press is preferably 2 times or more and less than 10 times for the same reason. Incidentally, the air permeability referred to in the present invention refers to Example C.I. It is a value obtained by the method described in the item.

The paper in the present invention refers to a sheet formed by a known papermaking technique using any one or a combination of fibrous, powdery, and fibrillar PPSO. As for the combination, any combination and mixing ratio may be used as long as the air permeability of paper made by papermaking is 1.0 cc / cm ² / sec or less. From the viewpoint of improving the strength of dielectric breakdown and preventing the paper from falling off, the fiber used preferably has a diameter of 5 nm to 15 μm, more preferably 10 nm to 10 μm, and most preferably 50 nm to 5 μm. For the same reason, the powder preferably has a diameter of 10 nm to 5 μm, more preferably 100 nm to 1 μm.

The fibrillar PPSO is a fibrous, powdery or membranous PPSO having a diameter of 1 μm or less and an aspect ratio of 3: 1 or more and a whisker-shaped portion, or a thickness of 1 μm or less and 1 mm ² or less. It is a film-like PPSO having a size.

  Fibrous and powdery PPSO can be obtained by oxidizing fibrous and powdery PPS by a known oxidation treatment method. Further, as a method for obtaining fibrillar PPSO, for example, a PPSO nanofiber obtained by oxidizing a tow made of PPS nanofiber obtained by a known technique (Japanese Patent Laid-Open No. 2006-257618) has a length of several mm. By beating the cut material in water, nanofibers are gathered in a bundle at a certain portion, and a pre-divided fiber is obtained at a certain portion.

  The paper in the present invention preferably contains 10% by weight or more, more preferably 50% by weight or more, and most preferably 75% by weight or more of fibrillar PPSO for the purpose of obtaining higher dielectric breakdown strength. By containing a large amount of such fibril-like PPSO, it is possible to efficiently fill the fiber gaps compared to normal fibers and powders, and a dense paper that is uniformly clogged even with a low basis weight can be obtained. , Leading to an improvement in the strength of dielectric breakdown. In addition, fibrillar PPSO has a large surface area, so that powder retention is good, and the yield of papermaking is improved. Further, the strength of paper is improved in order to increase the bond between fibers.

  The thickness of the paper of the present invention can be selected in the range of 5 μm to 1 mm according to the application. In addition, the thickness as used in the field of this invention is Example D.2. It is a value obtained by the method described in the item.

The basis weight of the paper of the present invention can be selected in the range of 10 to 900 g / m ² according to the application. In addition, the basis weight as used in the field of this invention is Example E.E. It is a value obtained by the method described in the item.

The air permeability of the paper of the present invention is preferably 0.10 cc / cm ² / sec or less for the purpose of obtaining higher dielectric breakdown strength. More preferably, it is 0.05 cc / cm ² / sec or less.

  The tensile strength of the paper of the present invention is preferably 10 N / 15 mm or more from the viewpoint of handleability. More preferably, it is 20 N / 15 mm or more, and most preferably 50 N / 15 mm or more. In addition, the tensile strength as used in the field of this invention is Example H.2. It is a value obtained by the method described in the item.

Hereinafter, the present invention will be described more specifically with reference to examples. In addition, each characteristic value in an Example was calculated | required with the following method.
A. The melting point of the sample was 10 mg with a differential scanning calorimeter (DSC manufactured by Perkin Elmer Co., Ltd.) under nitrogen at a heating rate of 10 ° C./min, and the temperature at which the observed main endothermic peak appeared was measured.
B. Viscosity Using the Toyo Seiki Capillograph 1B, the apparent viscosity at a shear rate of 1000 sec ⁻¹ was measured.
C. Air permeability According to JIS-L-1906 (revised in 2000) Frazier type method, using 8 pieces of paper cut into 10cm square per sample at 23 ° C and 50% relative humidity, manufactured by Textest Co., Ltd. Measure the amount of air (cc / cm ² / sec) passing through the test piece at a test pressure of 125 Pa with FX3300 using two significant digits, and obtain the average value of the eight values obtained using two significant digits. (Cc / cm ² / sec). When the average value was less than 0.05 (cc / cm ² / sec), the value of air permeability was set to less than 0.05 (cc / cm ² / sec).
D. Thickness In accordance with the test method of JIS-L-1906 (revised in 2000), a total of four corners and one central part for each 10 cm square piece of paper with a load of 10 kPa, 23 ° C. and 50% relative humidity. The thickness at five locations was measured to the order of 0.001 (mm). The average value of the results measured at five locations was determined, and the value obtained by rounding off the order of 0.1 μm was defined as the thickness L (μm). A value obtained by further averaging eight values of thickness L (μm) obtained from eight pieces of 10 cm square paper for the same sample was obtained, and a value obtained by rounding off the order of 0.1 μm was defined as average thickness L _mean (μm).
E. Basis weight, density The total weight (g) of 8 pieces of paper cut into 10 cm square per sample was measured at 23 ° C. and 50% relative humidity, and divided by 0.08 m ² , which is the area of the paper. The basis weight (g / m ² ) was calculated with a digit. In addition, the basis weight value is set to D. The average thickness L _mean measured in the section was divided by the value in cm, and the density (g / cm ³ ) was calculated with two significant figures.
F. Strength of dielectric breakdown Using any 5 pieces of 8 pieces of paper cut to 10 cm square per sample, according to the test method of JIS-K-6911 (2006 revision), an upper φ5 mm spherical electrode as an electrode, Measurement was performed at a voltage increase rate of 0.25 kV / sec in an atmosphere of 23 ° C. and 50% relative humidity using a lower φ10 mm disk electrode, and a dielectric breakdown voltage value was obtained to the order of 0.1 kV. . The value I _mean obtained by dividing the value of the obtained breakdown voltage by the value obtained by dividing the value of the thickness L of each paper in the unit of mm and the average value I _mean (kV / mm) by two significant digits The dielectric breakdown strength (kV / mm) was obtained.
G. Morphological observation The PPSO used for papermaking and the reference scale are magnified 150, 400, 3000, and 10,000 times with a scanning electron microscope (Nikon ESEM-2700) to understand the overall shape of PPSO, and The diameter and aspect ratio of the portion extending in a whisker-like shape were confirmed.
H. Using the Tensilon UCT-100 manufactured by Orientec Co., Ltd. in an atmosphere with a tensile strength of 23 ° C. and a relative humidity of 50%, the maximum point load value was measured at a sample width of 15 mm, an initial length of 20 mm, and a tensile speed of 20 mm / min. The average value of these measurements was obtained with two significant digits and was taken as the tensile strength (N / 15 mm).
[Reference Example 1]
(Synthesis of PPS)
An autoclave equipped with a stirrer was charged with 25 mol of sodium sulfide 9-hydrate, 2.5 mol of sodium acetate and N-methyl-2-pyrrolidone (hereinafter abbreviated as NMP). I put it out. Next, the reaction vessel was cooled to 180 ° C., 25.3 mol of 1,4-dichlorobenzene and NMP were added, sealed under nitrogen, heated to 270 ° C., and reacted at 270 ° C. for 2.5 hours. After cooling, the reaction product was washed 5 times with warm water, then heated to 100 ° C. and poured into NMP, stirred for about 1 hour, filtered, and washed several times with hot water. This was put into 25 liters of an acetic acid aqueous solution of pH 4 heated to 90 ° C., and stirred for about 1 hour, filtered, washed with ion-exchanged water of about 90 ° C. until the pH of the filtrate reached 7, PPS resin was obtained by drying under reduced pressure at 80 ° C. for 24 hours. The PPS resin had a melting point of 282 ° C. and a viscosity at a temperature of 320 ° C. of 200 Pa · s.
[Reference Example 2]
(Create fibrillar PPSO)
The PPS resin obtained in Reference Example 1 is kneaded with a polyethylene terephthalate having a melting point of 252 ° C. and a temperature of 320 ° C. and a melt viscosity of 100 Pa · s at a ratio of 40:60 (weight ratio) in a 300 ° C. biaxial kneader. A polymer was obtained. This alloy polymer was spun at a temperature of 320 ° C. using an existing single component spinning machine. At this time, the discharge amount is 35 g / min, the chimney has a temperature of 25 ° C., the wind speed is 25 m / min, a general oil agent is applied as a converging agent, and is taken up at a spinning speed of 1000 m / min, and 350.7 dtex 36 filament PPS alloy undrawn yarn Obtained. Further, this undrawn yarn was drawn 3.5 times between rollers having a first hot roller temperature of 90 ° C. and a second hot roller temperature of 150 ° C. to obtain a PPS alloy drawn yarn of 100 dtex 36 filaments. This drawn yarn had a strength of 3.8 cN / dtex and an elongation of 40%.

  The drawn yarn was shaped like a cake and immersed in an aqueous solution of sodium hydroxide having a temperature of 98 ° C. and a concentration of 10% for 3 hours to elute and remove polyethylene terephthalate to obtain a PPS ultrafine fiber assembly.

  99.0% acetic acid 1732 g (manufactured by Kishida Chemical), 577 g of 35% hydrogen peroxide (manufactured by Kishida Chemical), 144 g of 95% sulfuric acid (Wako Pure Chemical Industries) The mixture was dipped in a mixed solution and manufactured at 60 ° C. for 2 hours. The weight increased by 24.3%, and 230 g of PPSO ultrafine fiber aggregate, which is an oxide of PPS, was obtained.

  30 g of this ultrafine fiber assembly cut to a length of 2 mm was beaten in 20 L of water for 5 minutes using a test Niagara beater (No. 2505) manufactured by Kumagai Riki Kogyo. Using an automatic PFI mill (No. 2511-B) manufactured by Kogyo, beating was performed under the conditions of a beating load of 9 kg, a beating gap of 0.2 mm, and a roll rotation number of 9000 times. The obtained beating fiber contained a large amount of water, and the fiber concentration was 10 wt% from the measurement of dry weight.

When the form of the obtained beating fiber was confirmed with a scanning electron microscope, the ultrafine fibers were aggregated into a fibril shape, the ultrafine fibers were branched, the diameter was several tens to several hundred nm, and the aspect ratio was 1:10. Many portions extending in the above-mentioned beard shape existed, and fibrillar PPSO was obtained. The fibrillar PPSO thus obtained was measured by DSC and found to have substantially no melting point and good heat resistance.
[Reference Example 3]
(Creation of fibrous PPSO)
Using a known spinning machine using only the PPS resin obtained in Reference Example 1, the discharge amount was changed under the same conditions as in Reference Example 2, and melt spinning was performed to obtain a 1 dtex PPS drawn yarn. The drawn PPS yarn was cut to a length of 5 mm and subjected to an oxidation reaction in the same manner as in Reference Example 2 to obtain fibrous PPSO. When the obtained fiber was measured by DSC, it had substantially no melting point and good heat resistance.
[Reference Example 4]
(Making powdery PPSO)
NMP 330 g was added to 3.8 g of the PPS resin obtained in Reference Example 1, sealed under nitrogen, heated to 270 ° C., and dissolved at 270 ° C. for 10 minutes. Thereafter, the mixture was rapidly cooled at 10 ° C./min while stirring at 400 rpm, and 98 g of water was added when the temperature reached 180 ° C., followed by cooling to 60 ° C. After cooling, a liquid in which very fine particles were dispersed was obtained. The dispersion was centrifuged to precipitate particles, and the precipitate was washed by stirring in warm water at 70 ° C. for 30 minutes, and the washing operation for precipitation by centrifugation was repeated 5 times. When the precipitate after washing was dried, powdery PPS was obtained. This powdery PPS was oxidized in the same manner as in Reference Example 2 to obtain powdery PPSO. When the shape of this sample was observed with a scanning electron microscope, it was a nearly spherical particle having a diameter of several hundred nm. When the obtained powdery PPSO was measured by DSC, it had substantially no melting point and good heat resistance.

Example 1
A blender (Oster "Oster Blender OB-" of Oster Co., Ltd.) and 155 g of the hydrous beating fiber prepared in Reference Example 2 and 123 g of a cationic dispersant manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd. 1)) and stirred at a stirring speed of 10300 rpm for 30 minutes to obtain a dispersion.

  The obtained dispersion was put into a container of a laboratory paper machine (square sheet machine capable of forming a 25 cm square sheet) manufactured by Kumagai Riki Kogyo, and water was added to make a 20 liter preparation solution, followed by 150 mesh metal Paper was made on the net. The obtained paper was transferred onto a 25 cm square Advantech Co., Ltd. filter paper # 2 (5 μm), dried with a drum dryer, the sheet was peeled off from the filter paper, and a paper comprising 100% by weight of fibrillar PPSO was obtained. Obtained. The results of measuring the air permeability of this paper are shown in Table 1.

Two sheets of this paper were prepared in the same procedure, and four pieces of 10 cm square paper were cut out from each piece of paper and subjected to flat plate pressing at a temperature of 200 ° C., a pressure of 60 MPa, and a processing time of 3 minutes. Table 1 shows the average thickness, basis weight, density, air permeability, dielectric breakdown strength I _mean , and tensile strength of the obtained paper. The density of the paper was high and the insulation breakdown strength and tensile strength were excellent. Moreover, the dispersion of the value I of the breakdown strength before averaging was small, and there was no low value of less than 10 kV / mm.

Example 2
Using 77.5 g of the beating fiber in the moisture state prepared in Reference Example 2 and 7.75 g of the fibrous PPSO prepared in Reference Example 3, a dispersion was obtained in the same manner as in Example 1 to make paper, and 50% by weight of fibrillar PPSO was obtained. A paper consisting of 50% by weight of fibrous PPSO was obtained. The air permeability values of this paper are shown in Table 1.

Two sheets of this paper were prepared in the same procedure, and four sheets of 10 cm square were cut out from each piece of paper, and the average thickness, basis weight, density, and ventilation of the paper obtained by performing the press treatment in the same manner as in Example 1. Table 1 shows the values of strength, dielectric breakdown strength I _mean , and tensile strength. The density of the paper was high and the insulation breakdown strength and tensile strength were excellent. Moreover, the dispersion of the value I of the breakdown strength before averaging was small, and there was no low value of less than 10 kV / mm.

Example 3
Using 15.5 g of the beating fiber in the water-containing state prepared in Reference Example 2 and 14.0 g of the fibrous PPS prepared in Reference Example 3, a dispersion was obtained in the same manner as in Example 1 to make paper, and 10% by weight of fibrillar PPSO was obtained. A paper consisting of 90% by weight of fibrous PPSO was obtained. The air permeability values of this paper are shown in Table 1.

Two sheets of this paper were prepared in the same procedure, and four sheets of 10 cm square paper were cut out from each piece of paper, and the paper obtained was passed through a calendar processing machine composed of an iron roll and a paper roll. The calendar conditions were a temperature of 250 ° C., a load of 29 kN on a 10 cm wide paper, a pressure of 2.9 kN / cm, a roll peripheral speed of 2 m / min, and three passes. Table 1 shows the average thickness, basis weight, density, air permeability, dielectric breakdown strength I _mean , and tensile strength of the obtained paper. The density of the paper was high and the insulation breakdown strength and tensile strength were excellent. Moreover, the dispersion of the value I of the breakdown strength before averaging was small, and there was no low value of less than 10 kV / mm.

Example 4
A dispersion liquid was prepared in the same manner as in Example 1 using 77.5 g of the beating fiber containing water prepared in Reference Example 2, 7.02 g of fibrous PPSO prepared in Reference Example 3, and 0.78 g of powdered PPSO prepared in Reference Example 4. A paper made of 50% by weight of fibrillar PPSO, 45% by weight of fibrous PPSO, and 5% by weight of powdered PPSO was obtained. The air permeability values of this paper are shown in Table 1.

Two sheets of this paper were prepared in the same procedure, and four 10 cm square sheets were cut out from each piece of paper, and in the same manner as in Example 3, the pressure was 21 kN / cm at a temperature of 250 ° C., a load of 210 kN, and the roll peripheral speed was 2 m / min. Table 1 shows values of the average thickness, basis weight, density, air permeability, dielectric breakdown strength I _mean , and tensile strength of the paper obtained by performing the press treatment. The density of the paper was high and the insulation breakdown strength and tensile strength were excellent. Moreover, the dispersion of the value I of the breakdown strength before averaging was small, and there was no low value of less than 10 kV / mm.

Comparative Example 1
Using 15.5 g of the fibrous PPSO obtained in Example 3, a dispersion was obtained in the same manner as in Example 1 to make paper, and a paper composed of 100% by weight of fibrous PPSO was obtained. As shown in Table 1, the air permeability of this paper was very large compared with Examples 1-4.

Two sheets of this paper were prepared in the same procedure, and four sheets of 10 cm square were cut out from each piece of paper, and the average thickness, basis weight, density, and ventilation of the paper obtained by performing the press treatment in the same manner as in Example 1. Table 1 shows the values of strength, dielectric breakdown strength I _mean , and tensile strength. Although the density of the paper was low and the tensile strength was excellent, the value of the strength of dielectric breakdown was low and the paper could not withstand practical use as an insulating paper. The reason why the dielectric breakdown strength value is low is that the value of the air permeability of the paper is large before and after the press, and the density of the paper after the press is low. It is presumed that the gaps between the fibers remained and the insulating properties were lowered.

Comparative Example 2
An alloy polymer was obtained by kneading the PPS resin obtained in Reference Example 1 with polyethylene terephthalate having a melting point of 252 ° C. and a temperature of 320 ° C. and a melt viscosity of 100 Pa · s in a 30 ° C. biaxial kneader at 300 ° C. . This alloy polymer was spun at a temperature of 320 ° C. using an existing single component spinning machine. At this time, the discharge amount is 35 g / min, the chimney has a temperature of 25 ° C., the wind speed is 25 m / min, a general oil agent is applied as a converging agent, and is taken up at a spinning speed of 1000 m / min, and 350.7 dtex 36 filament PPS alloy undrawn yarn Obtained. Further, this undrawn yarn was drawn 3.5 times between rollers having a first hot roller temperature of 90 ° C. and a second hot roller temperature of 150 ° C. to obtain a PPS alloy drawn yarn of 100 dtex 36 filaments. The drawn yarn was cut to a length of 5 mm, and then immersed in an aqueous solution of sodium hydroxide having a temperature of 98 ° C. and a concentration of 10% for 3 hours to elute and remove the polyethylene terephthalate to obtain PPS nanofibers.

  800 mL of acetic acid (manufactured by Kanto Chemical Co., Inc.) and 46.16 g of sodium perborate tetrahydrate (0.30 mol; manufactured by Mitsubishi Gas Chemical Co., Inc.) were charged into the reaction vessel, and the nanofiber was stirred and dissolved at 60 ° C. . Next, 4 g of polyphenylene sulfide nanofibers were immersed in the reaction solution and subjected to an oxidation reaction treatment at 60 ° C. for 10 hours. The weight increased by 24.3%, and PPSO nanofibers, which are oxides of 5 g of PPS nanofibers. Got. The PPSO nanofibers thus obtained were fibers having substantially no melting point and good heat resistance.

  20 g of PPSO nanofibers were produced in the same manner, and dispersion was attempted with 20 liters of water using a 50 liter Niagara beater. The nanofibers were dispersed in about 15 minutes and a pulp-like product could be obtained. .

  4 liters of this dispersion was put into a handmade paper machine manufactured by Kumagai Riki Kogyo Co., Ltd. having a size of 25 cm × 25 cm and a height of 40 cm, water was added, and a small amount of polyvinyl alcohol paste was added. Stir. Water from the handmade paper machine was drained, the paper remaining on the wire mesh was transferred to filter paper, and the filter paper was put into a Japau dryer at a temperature of 125 ° C. and a speed of 0.5 m / min for drying treatment.

Two sheets of this paper were prepared in the same procedure, and the obtained paper was passed through a calendar processing machine composed of an iron roll and a paper roll. The calendar conditions were a temperature of 100 ° C., a load of 1 kN and a pressure of 0.04 kN / cm with respect to a 25 cm wide paper, and the load was a roll peripheral speed of 2 m / min, and was repeated three times. As described above, PPSO nanofiber paper having the same thickness as in Examples 1 to 4 was obtained. The average thickness, basis weight, density, air permeability, and dielectric strength I _{mean of} the paper obtained by cutting four pieces of 10 cm square paper from each piece of paper after pressing and performing the press treatment in the same manner as in Example 1. Table 1 shows the values of tensile strength.

As shown in Table 1, this paper had a low tensile strength and could not withstand practical use. In addition, although the dielectric breakdown strength I _mean is 10 kV / mm or more, there is a large variation in individual values I before averaging, and depending on the sample, there is a portion as low as less than 10 kV / mm, so it cannot be used as an insulating paper. It was a thing. Since the density of the paper is low compared to Examples 1 to 4, it is presumed that the hot press is insufficient, the tensile strength is low due to the low density of the paper, and the dielectric breakdown strength varies. The

Comparative Example 3
In the same manner as in Comparative Example 2, paper was made using 15.5 liters of the obtained dispersion of PPSO nanofibers to obtain paper made of PPSO nanofibers.

Two sheets of this paper were prepared in the same procedure, and calender pressing was performed in the same manner as in Comparative Example 2 to obtain a paper having a basis weight equivalent to that of Example 1. Table 1 shows the average thickness, basis weight, density, air permeability, dielectric breakdown strength I _mean , and tensile strength values of four 10 cm square paper cut out from each piece of paper after pressing.

As shown in Table 1, this paper had a low tensile strength and could not withstand practical use. In addition, although the dielectric breakdown strength I _mean is 10 kV / mm or more, there is a large variation in individual values I before averaging, and depending on the sample, there is a portion as low as less than 10 kV / mm, so it cannot be used as an insulating paper. It was a thing. Since the density of the paper is low compared to Examples 1 to 4, it is presumed that the hot press is insufficient, the tensile strength is low due to the low density of the paper, and the dielectric breakdown strength varies. The

  The PPSO paper of the present invention has excellent heat resistance, chemical resistance, and infusibility, as well as excellent insulation, so that it is used in various cable and wire coatings, printed circuit boards, motors, transformers, etc. Can be used as In addition, since it has high electrical insulation properties, it is possible to make the insulation layers of various devices that use electrical insulation paper more compact and contribute to improving its performance.

Claims (1)

Paper having a dielectric breakdown strength of 10 kV / mm or more and a density of 0.50 g / cm ³ or more composed of polyarylene sulfide oxide.