JP4710344B2 - Electrical insulation material - Google Patents

Description

  The present invention relates to a pulp excellent in heat resistance and chemical resistance for obtaining a dense paper having a small pore size, a method for producing the pulp, and a paper, and further to an electrical insulating material used in a motor, a transformer or the like.

  Polyarylene sulfide fibers (PPS fibers) are widely known as fibers excellent in heat resistance and chemical resistance. Further, as shown in JP-A-1-272863, JP-A-7-39735, and JP-A-5-230760, PPS fibers can be oxidized to obtain polyarylene sulfide oxide fibers (PPSO fibers). Ideas are also known. The polyarylene sulfide oxide fiber is a fiber having excellent heat resistance, chemical resistance, particularly acid resistance, and excellent heat resistance, as compared with the polyarylene sulfide fiber. However, the paper or pulp using polyarylene sulfide oxide fibers is not even disclosed or even suggested.

For electrical insulation materials used in motors and transformers, paper made of wet papermaking, such as paper made of cellulose, is often used. In particular, paper made of meta-aramid is often used as an electrical insulating material used at high temperatures. Since paper used at this high temperature is required to have heat resistance and chemical resistance, paper made of polyarylene sulfide fibers is a suitable material for basic performance. However, paper made of polyarylene sulfide fibers is not used as an electrical insulating material used at high temperatures. This is because the paper for electrical insulation requires a dense and small pore paper structure to improve electrical insulation, but polyarylene sulfide fibers cannot be pulped by beating. There is a problem. That is, the polyarylene sulfide fiber has a problem that it is impossible to obtain a dense paper having a small pore size.
JP-A-1-272863 JP 7-39735 A Japanese Patent Laid-Open No. 5-230760

In view of the problems of the background art, the present invention is to provide a pulp having excellent heat resistance and chemical resistance for obtaining a dense and small-sized paper, a method for producing the same, a paper, and an electrical insulating material. is there.

  The present invention employs the following means in order to solve such problems. That is, the pulp of the present invention is characterized in that in the pulp composed of short fibers having a fiber length of 0.01 mm to 10 mm, the pulp is composed of polyarylene sulfide oxide fibers having a branched structure or a fibril structure. It is what.

  In addition, such a pulp production method is characterized in that a polyarylene sulfide oxide fiber cut fiber is beaten by a mechanical action.

Furthermore, electrically insulating material of the present invention is an electrically insulating material which is composed of polyarylene sulfide oxide fibers of pulp and polyarylene sulfide oxide fibers mixed that contains the product paper and cut fibers, said The pulp is composed of short fibers having a number average fiber length of 0.01 mm to 10 mm, and further comprises a polyarylene sulfide oxide fiber having a branched structure or a fibril structure. There is .

  According to the present invention, it is possible to provide a dense and small-pore-size paper and, of course, excellent heat resistance and chemical resistance, so that it is an excellent material as an electrical insulating material used in motors and transformers. Can be provided.

  In the present invention, the above-mentioned problem, that is, a dense and small-pore size paper, has been intensively studied, and polyarylene sulfide is further oxidized to form a fiber using polyarylene sulfide oxide, and pulp is made from this fiber and beaten. As a result, it was discovered that the pulp has a branched structure or a fibril structure suitable for papermaking, and further papermaking using this pulp revealed that the problem could be solved at once. .

  That is, even if the polyarylene sulfide fiber conventionally used is beaten by a mechanical action, the fiber cross-section is merely deformed and crushed, and therefore, the basis weight unevenness is small from such a fiber. A dense paper was not obtained. Even if a paper is made from such polyarylene sulfide fibers, the electrical insulating material made of such paper is not only inferior in electrical insulation but also unusable.

  The present inventors discovered that the polyarylene sulfide fiber was oxidized to form a polyarylene sulfide oxide fiber, and when this was beaten, a pulp having a branched structure or a fibril structure was formed. The present invention has been achieved.

In the present invention, polyarylene sulfide oxide is
General formula (1)

(R ″ represents hydrogen, halogen, an aliphatic substituent substituted with an arbitrary 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 polyarylene sulfide oxide. R ′ ″ represents a polymer chain composed of polyarylene sulfide oxide. , M represents an integer of 0 to 3, n represents an integer of 0 to 2, and X represents 0, 1, or 2). Polymer or the above repeating unit as a main structural unit, and 1.0 mol or less, preferably 0.3 mol or less of general formulas (2) to (8) per mol of the repeating unit

(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 ″, R ″ ″ may be a polymer chain composed of polyarylene sulfide oxide. R ′ ″ represents a polymer chain composed of polyarylene sulfide oxide, m represents an integer of 0 to 3, and n Represents an integer of 0 to 2, and X represents 0, 1, or 2.) is a solid article composed of a copolymer having a repeating unit represented by the general formula: Of the repeating units represented by (1), X is 0. The ratio of the structural unit in which X is 1 or 2 in the structural units 1 and 2 is preferably 0.5 or more, and more preferably 0.7 or more.

  The polyarylene sulfide oxide fiber in the present invention is a fiber-shaped article composed of the polyarylene sulfide oxide described above. Here, the fiber is defined as having no branch structure or fibril structure before beating. The length / thickness ratio of the fibers may be any ratio as long as it is 1 or more, but is preferably 10 or more, more preferably 100 or more, and particularly preferably 1000 or more. The thickness of the fiber may be any thickness, but is preferably 1 mm or less, more preferably 100 μm or less, particularly preferably 20 μm or less, and even more preferably 5 μm or less. The thickness here refers to the distance of the longest part when the cross section of the fiber is viewed. If the cross section is circular, the diameter is the diameter, and if the cross section is rectangular, the length of the diagonal line is the thickness. . The cross-sectional shape of the polyarylene sulfide oxide fiber is not particularly limited, and is not limited to a normal circular cross-section, but a Δ cross-section, a Y-shaped cross section, a □ cross-section, a cross-section, a hollow cross-section, a C-shaped cross section, a rice field cross section Any irregular cross section can be adopted.

  The method for obtaining the polyarylene sulfide oxide fiber of the present invention may be any method, but is preferably obtained by oxidizing a fiber made of a polyarylene sulfide compound.

  The polyarylene sulfide compound referred to here is the following general formula (9)

(R represents at least 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. ) Or a repeating unit represented by formula (10) to (16) having a repeating unit of 1.0 or less, preferably 0.3 or less, per mole of the repeating unit. )

(R represents hydrogen, halogen, an aliphatic substituent substituted with an arbitrary functional group within an allowable range of valence, or an aliphatic substituent substituted with an aromatic substituent, and R ′ represents Represents an aliphatic substituent substituted with an arbitrary functional group within an allowable range of the valence.)).

  Among them, the substituents R and R ′ are preferably hydrogen or an aliphatic substituent having 1 to 4 carbon atoms. Specific examples thereof are hydrogen, methyl group, ethyl group, n-propyl group, iso-propyl group, and n-butyl group. , Iso-butyl group, and tert-butyl group. Among these, a methyl group, an ethyl group, an iso-propyl group, and a tert-butyl group are more preferable, and a methyl group is particularly preferable. Specific examples of such a polyarylene sulfide compound include poly-p-phenylene sulfide, poly-p-tolylene sulfide, poly-p-chlorophenylene sulfide, poly-p-fluorophenylene sulfide, and the like. , Poly-p-phenylene sulfide and poly-p-tolylene sulfide, more preferably poly-p-phenylene sulfide.

  Further, the polyarylene sulfide compound fiber preferably has physical properties of a crystallinity of 30% or more and a weight average molecular weight of 30000 (Mw) or more, and the crystallinity is preferably 50% or more. More preferred. The weight average molecular weight is more preferably 40000 (Mw) or more.

  When such a polyarylene sulfide compound fiber is used, the crystallinity and molecular weight of the polyarylene sulfide compound fiber are not greatly impaired even in the oxidation reaction treatment, and good results are obtained with respect to the physical properties of the resulting polyarylene sulfide oxide. Polyarylene sulfide compound fibers having such crystallinity and weight average molecular weight can be obtained, for example, by the following method.

  That is, when obtaining a polyphenylene sulfide compound having a weight average molecular weight of 30,000 (Mw) or more, sodium acetate is used as a polymerization aid used when polymerizing using sodium hydrosulfide as a sulfur source and p-dichlorobenzene as an organic monomer. The polymerization aid is obtained by polymerizing for about 4 hours under the condition that the excess of p-dichlorobenzene is 2.0 mol% or more with respect to sodium hydrosulfide, using 0.04 times mol or more of the polymerization aid relative to sodium hydrosulfide. be able to.

  Moreover, when obtaining the polyarylene sulfide compound fiber which has a crystallinity degree of 30% or more, these can be obtained by control of a drawing speed and a draw ratio, and the heat processing conditions after extending | stretching by a well-known method.

  The thickness (single yarn fineness) of the polyarylene sulfide compound fiber varies depending on the draw ratio and the draw speed and is not particularly limited, but is usually 0.1 to 10 dtex, preferably 0.5 to 9 dtex, more preferably 1 -7 dtex, particularly preferably 2.0 to 6.0 dtex.

  In the present invention, the liquid of the reaction solvent used for the oxidation reaction treatment can be arbitrarily used as long as it maintains the form of the polyarylene sulfide compound fiber, and uniformly dissolves the oxidizing agent used for the oxidation reaction treatment. It is preferable. Among them, a liquid containing an organic acid, an organic acid anhydride, or a mineral acid is preferable. The liquid may be either a single solvent or a mixed solvent, and may contain water or a liquid containing water alone. Specific examples of the liquid include water, acetone, methanol, ethanol, acetonitrile, tetrahydrofuran, chloroform, N-methylpyrrolidone, ethyl acetate, pyridine, organic acids and organic acid anhydrides described later. Specific examples of the organic acid include formic acid, acetic acid, trifluoroacetic acid, propionic acid, butyric acid, maleic acid and the like.

  Examples of such organic acid anhydrides include acid anhydrides represented by the following general formula (a).

(R1 and R2 each represent an aliphatic substituent having 1 to 5 carbon atoms, an aromatic substituent, or an aliphatic substituent substituted with an aromatic substituent, and R1 and R2 are linked to each other to form a cyclic group. May form a structure).

  Specific examples of such acid anhydrides include acetic anhydride, trifluoroacetic anhydride, propionic anhydride, butyric anhydride, maleic anhydride, succinic anhydride, phthalic anhydride, benzoic anhydride, and anhydrous chlorobenzoic acid. . Specific examples of the mineral acid include nitric acid, sulfuric acid, hydrochloric acid, phosphoric acid and the like. Among these acid anhydrides, preferred are water, acetic acid, trifluoroacetic acid, acetic anhydride, trifluoroacetic anhydride, sulfuric acid, and hydrochloric acid, and more preferred are water, acetic acid, trifluoroacetic acid, and sulfuric acid. Particularly preferred is a liquid in which water and acetic acid and sulfuric acid are mixed. More preferable composition ratios are: water: 5 to 20% by weight, acetic acid: 60 to 90% by weight, and sulfuric acid: 5 to 20% by weight. Good results are obtained at concentrations in this range.

  The oxidizing agent used in the oxidation reaction treatment can be arbitrarily used as long as it can be uniformly dissolved in the liquid and can give a polyarylene sulfide oxide having the characteristics defined in the present invention. Among them, a combination of an oxidant that can be oxidized while maintaining the shape of the polyarylene sulfide fiber and a solvent liquid is preferable. The oxidizing agent is preferably at least one selected from inorganic salt peroxides and hydrogen peroxide solutions, and one or more selected from inorganic salt peroxides and hydrogen peroxide solutions, organic acids and organic It may be a peroxide (including a peracid) formed from a mixture with one or more selected from acid anhydrides. Preferred examples of the inorganic salt peroxide used as the oxidizing agent include persulfates, perborates, and percarbonates. Here, examples of the salt include alkali metal salts, alkaline earth metal salts, ammonium salts, and the like, among which sodium salts, potassium salts, and ammonium salts are preferable. Specific examples thereof include sodium persulfate, potassium persulfate, ammonium persulfate as persulfates, sodium perborate, potassium perborate, ammonium perborate as perborate, and percarbonate as percarbonate. Examples thereof include sodium and potassium percarbonate. Specific examples of peracids formed from a mixture of hydrogen peroxide and an organic acid or organic acid anhydride include performic acid, peracetic acid, trifluoroperacetic acid, perpropionic acid, perbutyric acid, perbenzoic acid, m-chloroperbenzoic acid and the like can be mentioned, among which sodium persulfate, sodium perborate, performic acid, peracetic acid and trifluoroperacetic acid are more preferable, and sodium perborate and peracetic acid are more preferable. Trifluoroperacetic acid.

  The concentration of such an oxidizing agent is important for safety management in an industrial production method, and a higher concentration is preferable from the viewpoint of processing efficiency, but from the form and apparent volume of a solid article made of polyarylene sulfide compound fibers, As long as the solid article has a concentration sufficient to immerse in a solvent liquid containing an oxidizing agent and can obtain a polyarylene sulfide oxide in the range specified in the present invention, it is diluted with a solvent liquid, or a safety aspect. It is arbitrarily possible to reduce the concentration.

  The concentration of the oxidizing agent is preferably 20% by weight or less, more preferably 0.1% by weight to 10% by weight, and further preferably 3 to 8% by weight. A good reaction result can be obtained at a concentration within this range, and a highly safe process can be constructed. If it is higher than this, its stability and safety are very susceptible to temperature, and particularly with a high concentration of oxidant exceeding 20% by weight, it is difficult to manage its stability and process safety. Absent.

  It is possible to construct a process that gives good reaction results at a concentration in the above range and is highly safe. If it is higher than this, its stability and safety are very sensitive to temperature. In particular, a high concentration of peracid exceeding 20% by weight is not preferable because it is difficult to control its stability and process safety. .

  For example, using a differential scanning calorimeter (DSC-60: Shimadzu Corporation), the sample amount is weighed within a range of 5 mg to 8 mg in an air atmosphere, and the temperature is measured in a stainless steel 4.9 MPa (50 atm) pressure-resistant sealed container. The thermal behavior of the peracetic acid solution measured with the program set at 30 ° C to 200 ° C (from 30 ° C to 200 ° C with a 10 ° C / min temperature rise) is decomposed in the case of 40% peracetic acid solution. In the case of equilibrium peracetic acid having a temperature of 110 ° C. and a calorific value of 770 J / g, adjusted to a theoretical peracetic acid concentration of 40% using equal weight of acetic acid and 34.5% hydrogen peroxide, the decomposition temperature is 133 ° C. and the calorific value. In contrast to 704 J / g, a mixed liquid prepared by using equal weight of acetic anhydride and 34.5% hydrogen peroxide to a theoretical peracetic acid concentration of 40% has a decomposition temperature of 132 ° C. and 445 J / g of about 6%. The calorific value is 10%, and 9 %, The decomposition temperature is 110 ° C., 230 J / g, which is about one third of the calorific value, which is very small. Therefore, it is very important to ensure the safety of the oxidation reaction treatment process by reducing the oxidant concentration.

  Although this oxidation reaction treatment is not particularly limited as long as polyarylene sulfide oxide fibers having the characteristics specified in the present invention are obtained, it is preferably performed at a temperature below the boiling point of the liquid used. When the temperature is higher than the boiling point, the system is pressurized, the decomposition of the oxidant is often promoted and complicated equipment is required, and strict process management tends to be required in terms of safety. The specific oxidation reaction treatment temperature varies depending on the boiling point of the liquid to be used, but is within the range allowed by the boiling point of the liquid, preferably between 0 ° C. and 100 ° C., more preferably between about 30 ° C. and 80 ° C., particularly 40 ° C. ~ 70 ° C is preferred. For example, when the liquid is acetic acid, an oxidation reaction treatment temperature of 50 ° C. to 70 ° C. is preferable, and good reaction results are obtained at temperatures in this range.

  The oxidation reaction treatment time is not particularly limited as long as the polyarylene sulfide oxide fiber having the characteristics specified in the present invention is obtained, and the specific time depends on the reaction temperature and the concentration of the oxidizing agent, so that Although it cannot be said, for example, when the liquid is acetic acid, it is about 2 hours at 60 ° C. and 10% by weight of oxidizing agent.

  Further, it is usually about 1 to 8 hours at an oxidizing agent concentration of 5% by weight under 60 ° C conditions. Further, when a peracid formed from a mixture of an acid anhydride represented by the general formula (a) and hydrogen peroxide is used as an oxidizing agent, the oxidation reaction treatment is efficiently performed in a short time while ensuring safety. It is preferable. For example, in order to oxidize any of fiber bundles, fabrics, and felts when using equilibrium peracetic acid with acetic acid and 34.5% hydrogen peroxide water equivalent weight and theoretical peracetic acid concentration adjusted to 40% Is about 8 hours under a temperature condition of 60 ° C., whereas that of a mixed liquid prepared by using an equal weight of acetic anhydride and 34.5% aqueous hydrogen peroxide to a theoretical peracetic acid concentration of 40% is about 2 Time and very efficient.

  There is no particular limitation on the treatment method for performing the oxidation reaction treatment, but a batch type or continuous type, or a combination thereof can be adopted, and either a single-stage process or a multistage process can be adopted.

  Here, the batch type means that a fiber comprising a polyarylene sulfide compound and a liquid containing an oxidant are charged into an arbitrary reaction vessel and subjected to an oxidation reaction treatment at an arbitrary concentration, temperature, and time, and then polyarylene sulfide oxidation. This means a treatment method for taking out physical fibers or liquids, and the continuous type is an oxidation reaction treatment in which a fiber containing a polyarylene sulfide compound or a liquid containing an oxidizing agent is allowed to flow through a reaction vessel with an arbitrary flow rate. Means method. In the continuous type, a method of performing an oxidation reaction treatment by circulating or circulating a liquid containing an oxidant on a fiber composed of a polyarylene sulfide compound fixed in an arbitrary form, or a liquid containing an oxidant. Any method can be employed in which an oxidation reaction treatment is carried out by introducing into an arbitrary reaction vessel and continuously circulating or circulating fibers made of a polyarylene sulfide compound.

  Further, the multistage process means a process in which unit processes of oxidation reaction treatment adopting a batch type or a continuous type are constructed in a plurality or in stages. Specifically, the oxidation reaction treatment is divided into a plurality of times, and when each treatment is performed, a method of newly preparing a liquid containing an oxidant for performing the oxidation reaction treatment and performing the subsequent oxidation reaction treatment is exemplified. . Such a method is preferable in that the oxidation reaction can be promoted. Specifically, it is preferably used in that the oxidation reaction treatment time can be shortened and the reaction can be performed at a lower temperature. In particular, the oxidation reaction treatment that can occur by diluting with a liquid so that it is sufficiently immersed or reducing the concentration to ensure safety, due to the influence of the form and apparent volume of fibers made of polyarylene sulfide compounds This multi-stage process is preferable because it can suppress the extension of time and eliminate the need for excessive temperature rise. By adopting this process, safety is ensured without incurring an extended oxidation reaction time or temperature rise. Process construction can be done above.

  Furthermore, the method of contacting the fiber comprising the polyarylene sulfide compound with the liquid containing the oxidizing agent in the oxidation reaction treatment is a method of immersing the fiber comprising the polyarylene sulfide compound in the liquid containing the oxidizing agent, in any form. Any method of spraying or spraying a liquid containing an oxidant on a fiber comprising an immobilized polyarylene sulfide compound can be employed.

  The polyarylene sulfide oxide fiber obtained by oxidizing the fiber composed of the polyarylene sulfide compound as described above will be described in more detail.

  The cross-linking generated in the oxidation reaction treatment process in the present invention means forming a bridge structure between polymer molecules in the process of oxidizing the polyarylene sulfide compound, and the carbon atom contained in the structure of the repeating unit, It means that atoms selected from either sulfur atoms or oxygen atoms combine to form a bridge structure. In addition, the degree of cross-linking can be partially grasped by solid NMR analysis and differential thermogravimetric (TGA) measurement of the polyarylene sulfide oxide fiber, and in particular, in TGA measurement, thermogravimetry is performed under a nitrogen atmosphere. By measuring the amount of carbide remaining after the change evaluation, it is possible to grasp the ratio of the crosslinked structure between carbon atoms in the crosslinked structure. For example, using differential thermal weight (DTG-50: Shimadzu Corporation), a sample amount of about 10 mg is precisely weighed in a nitrogen atmosphere, and a temperature program is set to 30 ° C. to 900 ° C. (from 30 ° C. to 10 ° C. on a platinum cell container). The amount of remaining carbide when measured by setting the temperature to 900 ° C. at a temperature increase of ℃ / min) is that the polyarylene sulfide fiber (“Torcon (registered trademark)” manufactured by Toray Industries, Inc.) loses heat almost quantitatively. In the example of the polyarylene sulfide oxide fiber obtained after the oxidation treatment, 13.2% by weight of carbides remain, and a cross-linked structure of carbon atoms is formed by the oxidation treatment. I can confirm.

  In the polyarylene sulfide oxide fiber of the present invention, in such TGA measurement, it is preferable that residual carbide is substantially recognized, and it is preferable that the residual carbide amount is substantially 1% by weight or more. In particular, it is preferable to have a residual carbide amount of 5% by weight or more. Within this range, it has particularly excellent characteristics regarding heat resistance and chemical resistance. The term “substantially” used herein means the weight% of the amount of residual carbide after measurement with respect to the weight of the polyarylene sulfide oxide fiber before measurement in the differential thermal weight (TGA) measurement.

  Moreover, the polyarylene sulfide oxide fiber obtained by this oxidation treatment has crystallinity. That is, the crystallinity in the measurement of wide angle X-ray diffraction is preferably 10% or more, more preferably 30% or more, and particularly preferably 50% or more.

  Here, the degree of crystallinity is a value calculated from the peak area ratio derived from the crystalline structure in the total diffraction peak area, which is observed in the wide-angle X-ray diffraction measurement. For example, using a wide-angle X-ray diffractometer (RINT2100: Rigaku), a peak area ratio derived from a crystalline structure when a film having a sample thickness of about 70 μm is measured with a Cu source (λ = 1.5406 Å). Can be calculated.

  In the present invention, the polyarylene sulfide oxide fiber is crystalline so that the polyarylene sulfide fiber used for the oxidation reaction has a relatively high crystallinity and molecular weight, and the crystallinity of the polyarylene sulfide fiber is not excessively impaired. It can be increased by selecting conditions.

  Further, the polyarylene sulfide oxide fiber of the present invention preferably has a heat of fusion of 15 J / g or less, more preferably 10 J / g or less, more preferably 5 J / g or less, as measured with a differential scanning calorimeter (DSC). In particular, it means a polyarylene sulfide oxide fiber having a heat of fusion of 1 J / g or less, more preferably a polyarylene sulfide oxide fiber in which substantially no melting peak is observed. Within this range, it has particularly excellent characteristics regarding heat resistance and chemical resistance. Here, DSC measurement conditions were as follows: a differential scanning calorimeter (RDC220: Seiko Instruments) at a nitrogen flow rate of 20 mL / min in a nitrogen atmosphere, and a temperature program of 30 ° C. to 500 ° C. within a sample amount of 5 mg to 10 mg. (Temperature rises from 30 ° C to 340 ° C at 10 ° C / min., Hold for 2 minutes, then drop to 30 ° C by 10 ° C / min. Temperature drop, hold for 2 minutes, then to 500 ° C at 10 ° C / min. It is the amount of heat of fusion when it is set and measured. Such a polyarylene sulfide oxide fiber having a heat of fusion of 15 J / g or less can be produced by setting the oxidation treatment conditions to the above-described preferable conditions.

  The polyarylene sulfide oxide fiber thus obtained has heat resistance and chemical resistance, particularly acid resistance, higher than that of the polyarylene sulfide fiber, and has a feature that the melting point is lost and it does not melt by heat. Furthermore, it has been found that such polyarylene sulfide oxide fibers are very easy to grind and pulp can be easily obtained.

  A polyarylene sulfide oxide fiber cut to a length of 5 mm was beaten with a 50 liter Niagara beater at a fiber / water ratio of 200 g / 20 liter. The fiber was crushed in about 15 minutes and branched. Or the pulp which has a fibril structure was able to be obtained. The polyarylene sulfide fiber was beaten under the same conditions, but it was not even pulverized even after treatment for 2 hours.

  The branched structure here refers to a state in which one single fiber has a split in the length direction and is divided into a plurality of pieces in the length direction, and has a distribution of the number of constituents in the length direction. Say. The state divided into a plurality of lines may return to the state of one short fiber, or may be the state of the tip of the heel without returning. The fibril structure here refers to a structure in the same state as the above-mentioned branched structure. However, in the case of the fibril structure, each of the branched fibers is extremely thin and fine even when observed with an optical microscope. Each of the divided parts is invisible.

  The polyarylene sulfide oxide fiber pulp of the present invention has a branched structure or a fibril structure as described above, and is composed of short fibers whose pulp has a number average fiber length of 0.01 mm to 10 mm. It is what has been. If the fiber length of the pulp is too short, the pulp will not be entangled in the paper making process and will not accumulate in the paper.If it is too long, the pulp will be too entangled in the paper making process, resulting in poor dispersion. Not enough paper is available. The fiber length of the more preferable pulp is 0.05 mm to 5 mm, and more preferably 0.05 mm to 1 mm. Here, the number average fiber length is a fiber length defined by Σ (length of each fiber) / (total number of fibers).

  As described above, the polyarylene sulfide oxide fiber pulp of the present invention is obtained by beating a cut fiber of polyarylene sulfide oxide fiber by a mechanical action.

  The cut length of the polyarylene sulfide oxide fiber cut fiber may be any length as long as the number average fiber length is about 1 mm to 30 mm. However, if the cut length is too short, the fiber length of the pulp is shortened and cut. If the length is too long, the fiber length of the pulp becomes longer, which is not preferable. The cut length of the polyarylene sulfide oxide fiber is more preferably 3 mm to 15 mm, and particularly preferably 5 mm to 10 mm. That is, since the cut fiber is before beating, the fiber length is shortened by beating, and the cut fiber is cut longer than the pulp fiber length.

  The polyarylene sulfide oxide fiber cut fiber can be obtained by obtaining a polyarylene sulfide fiber cut fiber in advance by a known method such as a guillotine cutter and subjecting it to oxidation treatment. The fibers may be oxidized in the state of long fibers to obtain long fibers of polyarylene sulfide oxide fibers, and then cut fibers may be obtained by a known method. From the viewpoint of ease of work during the oxidation treatment, a method of performing an oxidation treatment after obtaining the polyarylene sulfide oxide fiber of the cut fiber is preferably used.

  The polyarylene sulfide oxide fiber cut fiber is beaten by a mechanical action to obtain a polyarylene sulfide oxide fiber pulp. However, the mechanical action in the present invention gives the action of grinding the cut fiber. Any means can be used. For example, at least one mechanical means selected from a beater, a homogenizer, a disc refiner, a reiki machine, a water jet punch using a high-pressure water stream, etc. can be preferably used. It can be crushed. However, the former mechanical means is good for efficient grinding.

The polyarylene sulfide oxide fiber of the present invention tends to be a pulp having a branched structure or a fibril structure due to mechanical action, and the fiber length tends to be shortened. Therefore, in order to obtain a good branched structure or fibril structure while maintaining a long fiber length, the dissimilar polymer is removed from the cut fiber obtained by dispersing polyarylene sulfide and a dissimilar polymer and spinning into a fiber shape. It is also preferable to beat the fibers in a state or in a state where the different polymer is removed by mechanical action.
This is because the force acting at the time of beating is concentrated at the interface with the dissimilar polymer dispersed in the polyarylene sulfide fiber, and the beating progresses in the fiber axis direction with a smaller force and prevents it from shortening in the length direction. I can do it. Furthermore, this effect becomes more prominent by eluting and removing the heterogeneous polymer.

  It is preferable that the polyarylene sulfide and the different polymer are uniformly dispersed because fine branches and fibrils are obtained. A preferable uniformly dispersed state is that the diameter of the different polymer in the dispersed polymer is less than 100 μm, more preferably less than 10 μm, still more preferably less than 1 μm, and particularly preferably less than 100 nm. If it is less than 10 nm, branching and fibrils after removal of the heterogeneous polymer become too small and the voids become small, which may not be preferable.

  The dissimilar polymer dispersed in polyarylene sulfide can be used as long as it is a polymer that can be eluted after spinning. Especially, polyarylene sulfide is excellent in chemical resistance and solvent resistance. It can be used if it can be eluted. Among them, for example, polymers that can be eluted by alkali treatment after spinning are represented by aromatic polyesters typified by polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc., or their copolymers and polylactic acid. Examples of the aliphatic polyester and the polymer that can be eluted by an organic solvent include polyolefins represented by polyethylene, polypropylene, and polystyrene, and examples of the polymer that can be eluted by an acid include polyamides such as nylon 6 and nylon 66.

  The polyarylene sulfide and the heterogeneous polymer can be dispersed and spun by a known method, and a polymer kneaded and dispersed in advance by chip blend spinning or a biaxial extruder can be spun by a known spinning machine.

  The polyarylene sulfide oxide fiber after elution and removal of the dissimilar dissimilar polymer is a fiber containing a lot of voids and a lot of branched structures and fibril structures, so it can be used as a pulp even without a beating treatment by mechanical action. There is no problem. Preferably, it is desirable that the beating process is performed to make the branched structure and the fibril structure more prominent.

  Furthermore, it is desirable that the elution process be performed before the beating by the mechanical action because it can be beaten more easily, but the elution process may be performed after the beating. Furthermore, it may be eluted after paper making of the paper described later.

  The polyarylene sulfide oxide fiber not only has excellent heat resistance and chemical resistance compared to the polyarylene sulfide fiber, but also has a feature that it does not have a melting point and therefore does not melt, so performance has been improved. Good paper can be obtained. In order to obtain a paper made of polyarylene sulfide oxide fibers, the polyarylene sulfide oxide fibers are cut to a length of about 1 mm to 10 mm, dispersed in water, made into paper, and then dried. As the paper making means employed here, a generally known wet paper making method can be used. The polyarylene sulfide oxide fiber used here may be either a fiber having crimps or a fiber having no crimps, but if fibers having crimps are used, the fibers are entangled during wet papermaking. It is preferable because the paper strength, which is the strength of the paper in a wet state, can be improved. Moreover, after drying, it can be set as a paper with improved dense paper strength by pressing at a high temperature by a method such as a calender roll.

It is important that the paper of the present invention is composed of pulp composed of polyarylene sulfide oxide fibers. Conventionally known papers made of polyarylene sulfide fibers have had a major problem in that it is impossible to obtain dense and small pore size paper because the polyarylene sulfide fibers could not be processed into pulp. However, since polyarylene sulfide oxide fibers can obtain pulp by a normal beating method, by making this pulp paper, not only heat resistance and chemical resistance are improved, it is difficult to heat melt, It is possible to greatly improve the extremely important properties of paper that is dense and has a small pore size.

Paper of the present invention, in such a polyarylene sulfide oxide fibers pulp, cut fibers of polyarylene sulfide oxide fibers by the mixture, thereby improving the paper strength. In such paper, the blending ratio of such polyarylene sulfide oxide fiber pulp may be in a range that does not impair the above effects, and is preferably at least 10% by weight, more preferably at least 30% by weight, particularly preferably at least at least. 40% by weight is good in terms of the balance between the effect of being dense and having a small pore size and the paper strength.

  Further, the paper of the present invention may contain components other than polyarylene sulfide oxide fiber pulp and cut fibers. For example, para-aramid fiber pulp can be mixed to improve paper strength. Other high-performance fibers such as polyarylene sulfide fiber, meta-aramid fiber, fluorine fiber, liquid crystal polyester fiber, polybenzoxazole fiber, and high-strength polyethylene fiber, polyethylene terephthalate fiber, polybutylene terephthalate fiber, polytrimethylene terephthalate fiber, polylactic acid Fiber, nylon 6 fiber, nylon 66 fiber, polyvinyl acetate fiber, or other general-purpose cut fiber or pulp, or natural fiber or pulp such as cotton fiber or wool fiber, or wood pulp may be mixed.

  The paper according to the present invention can be preferably used as an electrically insulating material. The paper used for the electrical insulating material is required to be a dense paper with a small pore size. This is because in the case of paper having a large pore size, an air portion exists in a state close to a straight line from the front surface to the back surface of the paper, and electricity passes through the air portion to cause dielectric breakdown. Usually, polymers have better electrical insulation than air, so having an air part from the front to the back in a state close to a straight line does not take advantage of the polymer's high electrical insulation, and the low electrical insulation of the paper That is, the electrical insulation property is determined.

  The paper using the polyarylene sulfide oxide fiber pulp of the present invention has many branched structures and fibril structures that the pulp has inside the paper. Thus, there is very little air portion that is close to linearly penetrating from the front to the back of the paper. In addition, the heat resistance and chemical resistance equal to or higher than those of the polyarylene sulfide fiber paper can be taken into account and the characteristics of not melting at a high temperature can be taken into consideration.

  The electrical insulating material of the present invention is inserted between the high voltage side and the low voltage side in order to prevent a short circuit between the high voltage side and the low voltage side of the rotator (motor) or transformer (transformer). It is a member. It may be used only with paper, but it may be used by combining paper and film, or by combining with other materials.

  Such an electrical insulating material may be used by impregnating with resin or oil. When the resin or oil is impregnated, the air portion is almost absent, so that the electric insulation resistance can be further increased.

  As the resin, an epoxy resin, a phenol resin, a polyimide resin, or the like is preferably used, but other resins may be used. As the oil, silicone oil or the like is preferably used in addition to mineral oil or vegetable oil, but other oils may be used.

  Hereinafter, the present invention will be described in more detail with reference to examples.

<Example 1> (Reference example)

As a raw material of the polyarylene sulfide oxide fiber, 1.0 dtex-6 mm which is a polyarylene sulfide fiber “Torcon” (R) staple fiber cut fiber manufactured by Toray Industries, Inc. was prepared. This cut fiber is a crimped fiber.

  800 L of acetic acid (manufactured by Kanto Chemical Co., Inc.) and 46.16 kg of sodium perborate tetrahydrate (0.30 mol; manufactured by Mitsubishi Gas Chemical Co., Ltd.) were put into a reaction vessel, and stirred and dissolved at 60 ° C. Next, when 4.03 kg of polyarylene sulfide fiber cut fiber was 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 5.01 kg of polyarylene sulfide was obtained. A polyarylene sulfide oxide fiber cut fiber, which is a fiber oxide, was obtained.

  Although the resulting polyarylene sulfide oxide fiber cut fiber has increased weight, the fineness is increased, but in the examples of the present invention, the fineness designation of the polyarylene sulfide fiber cut fiber that is the raw material is used as it is. Polyarylene sulfide oxide fiber cut fiber 1.0 dtex-6 mm.

200 g of polyarylene sulfide oxide fiber cut fiber 1.0T-6 mm obtained as described above was put into a 50 liter type Niagara beater together with 20 liters of water. This Niagara beater was operated for 30 minutes to carry out a beating process to obtain a polyarylene sulfide oxide fiber pulp.
It was 0.36 mm when the number average fiber length was measured for the obtained pulp using the fiber length distribution meter of KAJANI FS-200. Due to the mechanical impact of the beater, the fiber length was considerably shortened. Further, when the obtained pulp was magnified and observed with a microscope, the portion where the short fibers were divided in the fiber axis direction and had a branched structure and the fiber tip were finely branched like a cocoon to have a fibril structure. I was able to see the part that was doing.

<Example 2> (Reference example)
A polyarylene sulfide having a melt viscosity of 2000 poise and polyethylene terephthalate having a melt viscosity of 3200 poise were mixed at a ratio of 80:20 and kneaded by a biaxial extruder at 310 ° C. to obtain a chip. This chip was dried at 150 ° C. for 4 hours using a vacuum dryer to obtain a dried chip.

The chip was spun at a spinning temperature of 315 ° C. and a spinning speed of 1000 m / min using a known spinning machine to obtain an undrawn yarn of 4650 dtex and 300 filaments, and subsequently 3.1 at a drawing temperature of 100 ° C. and a set temperature of 160 ° C. Double drawing was carried out to obtain a drawn yarn having a strength of 4.1 cN / dtex and an elongation of 27% with 1500 dtex and 300 filaments. The drawn yarn was cut to a length of 6 mm with a guillotine cutter, and then treated with an alkaline aqueous solution at 95 ° C. and 10% for 4 hours to elute and remove polyethylene terephthalate to obtain a polyarylene sulfide porous cut fiber.
This porous cut fiber was oxidized by the same method as in Example 1 to obtain a porous polyarylene sulfide oxide fiber cut fiber.
This porous polyarylene sulfide oxide fiber cut fiber was beaten under the same conditions as in Example 1 to obtain a polyarylene sulfide oxide fiber pulp. However, the operation time of the beater was 15 minutes, which was 1/2 of the operation time of Example 1.
As a result of measuring the fiber length distribution of the obtained pulp in the same manner as in Example 1, the number average fiber length was 0.57 mm, and the fiber length was longer than that of the pulp obtained in Example 1 and was a good pulp. It was.
When the obtained pulp was microscopically observed in the same manner as in Example 1, the part having a branched structure and the part having a fibril structure were compared with the pulp obtained in Example 1. Thus, it was remarkably increased and was a better pulp than the pulp obtained in Example 1. That is, compared with the pulp obtained in Example 1, the branch structure portion and the fibril structure portion are increased, so that the volume of the space without fibers (with fibers when observed with a microscope). It was found that the pore size when using paper was definitely reduced.

<Example 3>
2 g of polyarylene sulfide oxide fiber pulp and 2 g of polyarylene sulfide oxide fiber cut fiber obtained in Example 1 were prepared. These raw materials and water were put into a household mixer and dispersed. This dispersion was put into a handmade paper machine manufactured by Kumagai Rikkoku Kogyo Co., Ltd. having a size of 25 cm × 25 cm and a height of 40 cm, water was further added, and a slight amount of a paste material of polyvinyl alcohol was added and further stirred. .
Water from the handmade paper machine was drained, the paper remaining on the wire mesh was transferred to a 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. The dried paper was peeled from the filter paper and passed through a calendering machine consisting of an iron roll and a paper roll. The calendar conditions were a temperature of 100 ° C., a load of 100 kN / 25 cm, and a roll peripheral speed of 2 m / min with respect to a 25 cm width paper.
As described above, a paper having a 50:50 mixing ratio of polyarylene sulfide oxide fiber pulp and polyarylene sulfide oxide fiber cut fiber was obtained.

Good paper was obtained except that the basis weight of the obtained paper was 57 g / m ² , the thickness was 0.08 mm, the paper strength was 8 N / cm, and the paper strength was slightly weak.

  The obtained paper was a dense paper with few voids, and the dielectric breakdown voltage was measured. As a result, it was 0.8 kV / mm, which was improved from the paper of Comparative Example 2 described later.

<Example 4> (Reference Example)

2 g of polyarylene sulfide oxide fiber pulp obtained in Example 1 and 2 g of polyarylene sulfide fiber cut fiber as the raw material were prepared. Using these raw materials, paper was prepared in exactly the same manner as in Example 3 to obtain a paper with a 50:50 mixture ratio of polyarylene sulfide oxide fiber pulp and polyarylene sulfide fiber cut fiber.

The basis weight of the obtained paper was 55 g / m ² , the thickness was 0.08 mm, the paper strength was 10 N / cm, and the paper strength was improved as compared with Example 3. This is because the polyarylene sulfide fiber cut fiber has a melting point, so it is easily softened by heat and pressure, and it can be presumed that it acts as a binder in calendering and has improved paper strength.

  The obtained paper was a dense paper with few voids, and the dielectric breakdown voltage was measured. As a result, it was 0.8 kV / mm, which was improved from the paper of Comparative Example 2 described later.

<Comparative Example 1>
The same polyarylene sulfide fiber “Torcon” (R) staple fiber cut fiber 1.0 dtex-6 mm manufactured by Toray Industries, Inc. was prepared as prepared in Example 1. The cut fiber was beaten under the same conditions as in Example 1 without oxidation treatment to attempt polyarylene sulfide oxide fiber pulping. However, the operation time of the beater was 60 minutes, twice the operation time of Example 1.
As a result of measuring the fiber length distribution of the obtained pulping prototype by the same method as in Example 1, the number average fiber length was 4.5 mm, there was no fiber length, and it was not beaten by mechanical impact. . Moreover, when the obtained pulping prototype was observed with a microscope in the same manner as in Example 1, no part having a branched structure or part having a fibril structure was found at all. . That is, it was confirmed that pulp was not obtained with polyarylene sulfide fibers.

<Comparative Example 2>
The same polyarylene sulfide fiber “Torcon” (R) staple fiber cut fiber 1.0 dtex-6 mm manufactured by Toray Industries, Inc. was prepared as prepared in Example 1. Using only 4 g of this cut fiber, a paper was prepared in exactly the same manner as in Example 3 to obtain a paper with 100% polyarylene sulfide fiber cut fiber.
The basis weight of the obtained paper was 59 g / m ² , the thickness was 0.08 mm, and the paper strength was 15 N / cm.

  Since the obtained paper does not use pulp, it is a rough paper with many voids. When the dielectric breakdown voltage was measured, it was 0.6 kV / mm, and the pulp containing Example 3 or Example 4 contained pulp. It was inferior to paper.

Claims (6)

An electrically insulating material composed of a paper composed of a mixture of polyarylene sulfide oxide fiber pulp and polyarylene sulfide oxide fiber cut fiber, wherein the pulp has a number average fiber length of 0.01 mm. An electrically insulating material comprising a short fiber having a diameter of -10 mm and further comprising a paper composed of a polyarylene sulfide oxide fiber having a branched structure or a fibril structure . The electrical insulating material according to claim 1, wherein the polyarylene sulfide oxide fiber is composed of a polymer composed of a repeating unit represented by the following general formula (1) .

(R ″ represents hydrogen, halogen, an aliphatic substituent substituted with an arbitrary 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 polyarylene sulfide oxide. R ′ ″ represents a polymer chain composed of polyarylene sulfide oxide. M represents an integer of 0 to 3, n represents an integer of 0 to 2, and X represents 0, 1, or 2.) 3. In the repeating unit represented by the general formula (1), the ratio of the structural unit in which X is 1 or 2 in the structural unit in which X is 0, 1, or 2 is 0.5 or more. Electrically insulating material as described in . The polyarylene sulfide oxide fiber is represented by the general formulas (2) to (8) having the repeating unit as a main structural unit and 1.0 mol or less, preferably 0.3 mol or less per mol of the repeating unit. The electrically insulating material according to claim 2 or 3, wherein the electrically insulating material is composed of a copolymer comprising the repeating units shown .

(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 ″, R ″ ″ may be a polymer chain composed of polyarylene sulfide oxide. R ′ ″ represents a polymer chain composed of polyarylene sulfide oxide, m represents an integer of 0 to 3, and n Represents an integer of 0 to 2. X represents 0, 1, or 2.) The electrically insulating material according to any one of claims 1 to 4, wherein the paper contains at least 30% by weight of polyarylene sulfide oxide fiber pulp . The paper, electrical insulating material according to any of claims 1 to 5, resin or oil is one that was impregnated.