TWI601582B - Method for producing raw material for papermaking, raw material for papermaking obtained, and heat-resistant electrical insulating sheet using the same - Google Patents

Description

a method for producing a raw material for papermaking, a raw material for papermaking obtained, and a heat-resistant electrically insulating sheet using the raw material

The present invention relates to a method for recycling a calendered polyaramide paper and a heat resistant electrical insulating sheet. In particular, the present invention relates to a calendered polyaryl that can be regenerated by calendering or polyaniline paper which has been treated by incineration or disposal without the use of a chemical solution. A method of recycling a guanamine paper, and a heat-resistant electrically insulating sheet.

Papers have been developed which are made of high performance materials and therefore have better strength and/or thermal stability. For example, polyarsenin paper, which is a synthetic paper made of aromatic polyamine, can be used as an electrical insulating material because of its excellent heat resistance, flame resistance, electrical insulation, toughness and flexibility. The substrate of the honeycomb structure of the aircraft. Such materials also include paper formed by DuPont (USA) Nomex (registered trademark) fibers, which are produced in the following manner: poly(metaphenylene isophthalamide) (poly(metaphenylene isophthalamide)) )) The short fibers and the fibrid are mixed in water, and then the mixed slurry is subjected to papermaking, followed by calendering. It is currently known that such papers still have high strength and toughness at high temperatures, and have excellent electrical insulation properties.

Due to the high temperature and high pressure treatment of the melamine paper, the waste and the damaged material cannot be completely fibrillated by water, so it must be incinerated or discarded. deal with. Further, after being dissolved in an organic solvent, chemical regeneration may be carried out to form a papermaking raw material similar to the initial raw material, that is, short fibers, fibrids, pulp, etc., but the method requires consideration of environmental factors, and the cost may vary. high.

Further, the processing methods described in Patent Documents 1 and 2 are related to a method for regenerating dry polyarylamide paper or polyarylimine paperboard which is subjected to high temperature and high pressure treatment which is not subjected to calendering. However, polyarylamide papers are mostly used after calendering, so these methods are not practical.

Furthermore, the method described in Patent Document 3 uses a polyarsenide pulp which is formed by pulverizing a polyarylamine paper, and a mass ratio of 90/10 to 10/90 with a non-polyarsenamide fiber. After the mixed papermaking is formed into a sheet shape, the porous polyamidamine molded article is produced. However, since the molded article is porous, it is generally considered to have poor electrical insulating properties.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 4-228696

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2003-290676

[Patent Document 3] Japanese Patent Laid-Open No. Hei 7-243189

An object of the present invention is to provide a method for producing a raw material for papermaking, which is capable of disintegrating a light-processed polyarylamide paper into a reusable raw material for papermaking without using a chemical liquid. Raw materials for papermaking.

Another object of the present invention is to provide a raw material for papermaking which is obtained from calendered polyaramide paper.

Another object of the present invention is to provide a heat-resistant electrically insulating sheet which uses the above-mentioned raw material for papermaking.

The present invention has been accomplished on the basis of the following findings: When a specific polyaramide paper produced by calendering is subjected to high-pressure jet treatment to be broken, a raw material for papermaking having excellent characteristics and recyclable can be obtained.

That is, the present invention provides a method for producing a raw material for papermaking, which comprises a fibril formed from an aromatic polyamine, a short fiber, or a mixture thereof, and is produced by calendering. The guanamine paper is subjected to high pressure jet treatment to break up the polyamidamide paper.

The present invention further provides a raw material for papermaking which is obtained by the above production method.

The present invention further provides a heat-resistant electrically insulating sheet comprising the above-mentioned raw material for papermaking.

(polyarylamine, aramid)

In the present invention, polyarsenamide refers to a linear polymer compound (aromatic polyamine) in which 60% or more of a guanamine bond is directly bonded to an aromatic ring. Such polyarylamines are, for example, poly(phenylene isophthalamide) and copolymers thereof, polyparaphenylene terephthalamide and copolymers thereof, and poly(p-phenylene) ())-(3,4-diphenyl ether) poly(paraphenylene)-copoly(3,4diphenylether) terephthalamide or the like. The polyarylamines can be obtained by, for example, using isophthalic acid Commercially produced by a conventional interfacial polymerization method, a solution polymerization method, or the like of a formic acid chloride or m-phenylenediamine, and may be obtained from a commercially available product, but is not limited thereto. From the viewpoint of having characteristics such as good moldability, thermal adhesiveness, flame retardancy, heat resistance and the like, it is preferred to use poly(m-phenylene phthalamide) among the polyarylamines.

(polyarylamine fibrid)

In the present invention, the polyarylamine fibrids are paper-like guanamine particles having a papermaking property, which is also called aramid pulp (refer to Japanese Patent Publication No. 35-11851, Japanese Special Public Sho. Bulletin No. 37-5732, etc.).

It is known that polyarsenide fibrids can be subjected to decomposition and beating treatment in the same manner as general wood pulp, and can be used as a papermaking raw material; it can be subjected to a beating treatment for maintaining the quality suitable for papermaking. The beating treatment can be carried out by a disc refining apparatus, a beating apparatus, and other papermaking raw material processing equipment capable of exerting a mechanical cutting action. In this operation, the morphological change of the fibrids can be monitored by the freeness test prescribed by Japanese Industrial Standards (JIS) P8121. In the present invention, the freeness of the polyarylamine fibrids after the beating treatment is preferably in the range of 10 cm ³ to 300 cm ³ (Canadian freeness). The strength of the heat-resistant electrically insulating sheet formed by the fibrids having a range of freeness larger than the range may be lowered. On the other hand, when the degree of freeness is less than 10 cm ³ , the use efficiency of the input mechanical power is reduced, and the amount of treatment per unit time is reduced. Further, the fibrid body is excessively fined to facilitate the adhesion function. reduce. Therefore, it is not considered that the freeness is less than 10 cm ³ has a particular advantage.

(polyarsenamide short fiber)

The polyarylamine short fibers are cut with fibers of polyarmine amine as a material. This type of fiber is such as: "TEIJIN CONEX (registered trademark)" of Teijin Co., Ltd., DuPont "NOMEX (registered trademark)", etc., but is not limited to this.

The length of the polyarylamine short fibers is generally selected from the range of 1 mm or more and less than 50 mm, and is preferably selected from the range of 2 to 10 mm. When the length of the short fibers is less than 1 mm, the mechanical properties of the sheet are lowered. Further, when the length is 50 mm or more, when the polyamidamide paper is produced by a wet method, "tangling" and "winding into bundles" are likely to occur. Waiting for the situation, it is easy to become the cause of the defect.

(polyarylamine paper)

In the present invention, the polyarylamine paper is a sheet mainly composed of the above-mentioned polyarylamine fibrids, polyarsenamide short fibers, or a mixture thereof, and generally has a thickness of 20 μm to 1000 μm. In the range. Furthermore, polyarylamine papers generally have a basis weight in the range of 10 g/m ² to 1000 g/m ² .

In general, polyaramide paper is produced by mixing the above-mentioned polyarylamine fibrids and polyarmine light fibers and then flaking them. Specifically, the following methods can be used: a method of forming a sheet by air flow after dry mixing of the above-mentioned polyarylamine fibrids and polyarsenamide short fibers; and polyarylene fibril and polyarylene a method in which an amine short fiber is dispersed and mixed in a liquid medium, and then poured onto a support having a liquid permeability (for example, a mesh or a belt) to be flaky, and then the liquid is removed to dry it; in the foregoing method, It is preferred to select a so-called wet manufacturing method using water as a medium. Here, the polyarylamine fibrids and the polyarylamine short fibers may be mixed in any ratio, but the ratio (mass ratio) of the polyarylamine fibrids/polyarsenamide short fibers is preferably 1/9~ 9/1, more preferably 2/8~8/2.

In the wet manufacturing method, an aqueous slurry containing at least a polyaminin fibrid, a single species of polyarmine amine short fibers or a mixture thereof is supplied to a paper machine to be dispersed, and then dehydrated and squeezed. And a drying step to obtain a sheet and wind it up. Paper machine A long-wire paper machine, a rotary paper machine, a tilting paper machine, and a hybrid paper machine obtained by combining the same. In the case of production by a hybrid paper machine, the slurry having different blending ratios can be formed into a sheet and integrated to obtain a composite sheet formed of a plurality of paper layers. When performing papermaking, if necessary, additives such as a dispersibility enhancer, an antifoaming agent, and a paper strength enhancer may be used.

(砑光加工)

It is known that the polyaramide paper obtained by the above method can be heated under high temperature and high pressure between a pair of rollers, and the density, crystallization degree, heat resistance and dimensional stability can be improved, and the machine can be lifted. strength. For example, in the case of using a metal drum, the hot pressing conditions exemplified are a temperature of 100 to 350 ° C and a linear pressure of 50 to 400 kg/cm, but are not limited thereto. When hot pressing, a plurality of polyamido papers may be stacked. The above hot press processing can also be performed multiple times in any order.

(high pressure jet treatment)

In the present invention, the high-pressure jet treatment refers to a treatment in which the above-mentioned calendered polyaramide paper is immersed in water and sprayed with water from a nozzle at a high pressure to cause it to collide with a hard object for collision. Or causing the high-pressure jetting of the above-mentioned calendered polyarsenamide paper to collide with each other, thereby disintegrating the above-mentioned calendered polyarylamide paper to form polyarylamine fibrids and polyarylene A similar shape of the amine staple fiber.

A high-pressure homogenizer is preferably used as the apparatus capable of performing such treatment, but is not limited thereto.

Here, the shape of the impact hard object is, for example, a spherical shape or a flat shape, but is not limited thereto. Further, the diameter of the high pressure jet nozzle is preferably 0.1 to 0.9 mm, but is not limited thereto.

Further, in the case of high-pressure jetting, it is preferred to previously calender the above by a pulverizer or the like. The polyarsenamide paper is pulverized until the weight average of the fiber length is 3 times or less, preferably 2 times or less, more preferably 1.5 times or less. When it is 1.5 times or less, the above-mentioned calendered polyarsenamide paper clogging nozzle can be effectively suppressed.

The method of pulverizing the above-mentioned calendered polyaramide paper is preferably a method of pulverizing and pulverizing it by a dry method, a wet method or both methods in parallel. The dry method uses a shredder, a crusher, a kneader, or the like to pulverize the polyamidamine paper into fine particles without actually having moisture. . Further, the wet method is a method in which polyarsenamide paper is washed in an aqueous medium to reduce the particle size. The apparatus capable of effectively performing such wet pulverization is, for example, a high-speed disintegrator, a refiner, a beater, or the like, but is not limited thereto.

In terms of the conditions of the high pressure jet treatment, the injection pressure is preferably in the range of 70 to 300 MPa. The ejection speed is preferably in the range of 300 to 900 m/s.

Further, when the above-mentioned calendered polyaramide paper is immersed in water, the concentration thereof is preferably from 0.1 to 10% by weight. When immersed in water, if necessary, additives such as a dispersibility enhancer and an antifoaming agent may be used.

If necessary, the high-pressure jet treatment may be repeated a plurality of times, but if the number of times is too high, the cost becomes high; further, if the operation of cutting off the part of the short-cut fibers of the guanamine is continued, it does not stay as a raw material for papermaking. Short fiber shape, it is not good. That is, the retention ratio of the weighted average of the fiber lengths of the above-mentioned calendered polyaramide paper before and after the high pressure jet treatment is preferably 80% or more.

(volume average particle size distribution, particle diameter peak)

In the present invention, the volume average particle size distribution is a particle measured on a volume basis. Sub-distribution. Further, the volume average particle diameter is a particle diameter measured on a volume basis. Further, the particle diameter peak is the peak of the volume average particle size distribution. In addition, since the raw material for papermaking of the present invention has a three-dimensional shape such as a fiber shape, a particle shape, or an indefinite shape, the size and shape of the raw material for papermaking are determined by the particle diameter peak.

Further, it is considered that, in the volume average particle size distribution, the peak of the particle diameter in the range of 10 μm or more and less than 100 μm mainly represents the relative amount of the polyarsenide short fibers after decomposition; the above particle diameter occurs after the high pressure jet treatment The peak value indicates the presence of polyarmine short fibers.

Therefore, the present invention preferably employs a high-pressure jet treatment in such a manner that a volume average particle size distribution of the polyamidamide paper after the high-pressure jet treatment is 10 μm or more and a particle diameter peak within a range of less than 100 μm, so that it is easy to be short. The fibers are entangled to enhance the strength of the heat-resistant electrically insulating sheet.

More preferably, the high-pressure jet treatment is carried out in the following manner: the polyarylamide paper is pulverized before the high-pressure jet treatment, so that the particle diameter peaks in the volume average particle size distribution of the polyarylamide paper before the high-pressure jet treatment are respectively at 10 μm. In the range of less than 100 μm and in the range of 100 μm or more and less than 1000 μm, the peak frequency of the particle diameter in the range of 10 μm or more and less than 100 μm after the high-pressure jet treatment is increased, and is located at 100 μm or more. The peak frequency of the particle diameter in the range of up to 1000 μm is reduced.

In our opinion, in the volume average particle size distribution of the above-mentioned calendered polyarylamide paper, the peak of the particle diameter in the range of 10 μm or more and less than 100 μm mainly indicates the relative amount of the polyarylamine short fibers after decomposition. The peak of the particle diameter in the range of 100 μm or more and less than 1000 μm mainly represents the relative amount of the mixture of the undecomposed polylinamide short fibers and the polyarylamine fibrids; after the high pressure jet treatment, the former particles The peak frequency of the diameter will increase, and the particle size peak of the latter The frequency of the values is reduced, which means that the amount of polyarmine short fibers is relatively increased, while the amount of the mixture of undecomposed polylinamide short fibers and polyarylamine fibrids is relatively reduced.

Thereby, the short fibers are easily entangled, which not only improves the strength of the heat-resistant electrically insulating sheet, but also reduces the problem of the difference in thickness of the heat-resistant electrically insulating sheet.

(heat-resistant electrical insulation sheet)

The heat-resistant electrically insulating sheet of the present invention is a sheet-like material containing the raw material for papermaking, and generally has a thickness in the range of 20 μm to 5 mm. Furthermore, the basis weight of the heat-resistant electrically insulating sheet is generally in the range of 10 g/m ² to 5000 g/m ² , preferably in the range of 10 g/m ² to 200 g/m ² .

In the heat-resistant electrically insulating sheet, the content of the raw material for papermaking is not particularly limited as long as the desired electrical insulation can be achieved, and in the manufacture of the heat-resistant electrically insulating sheet, in order to maintain the process strength, the content is higher. Preferably, the content is 5 to 80% by mass; further, in order to obtain sufficient electrical insulation, the content is preferably 15 to 80% by mass; further, in order to obtain sufficient strength, the content is preferably 30~ 80% by mass. The remainder may be a new polyarylamine fibrid or a mixture with polyarylamine short fibers, but is not limited thereto.

The heat-resistant electrically insulating sheet is generally produced by a method in which the above-mentioned raw material for papermaking is mixed with a polyamidoamine fibrid or the like and then flaky.

When the sheet is produced, a method of forming a sheet by air flow after dry-mixing the raw material for papermaking with a polyamidoamine fibrid, and using the raw material for papermaking and the polyarylamine fibrid in a liquid medium can be used. After dispersing and mixing, it is fed to a support having a liquid permeability (for example, a mesh or a belt), which is flaky, and then the liquid is removed to dry it. In the above method, it is preferred to select water. A so-called wet manufacturing method as a medium.

In the wet manufacturing method, an aqueous slurry containing at least the raw material for papermaking, a single type of polyarylene fibril, or a mixture thereof is supplied to a paper machine to be dispersed, and then dehydrated, squeezed, and dried. The step is to wind up the sheet to obtain the sheet. The paper machine can use a long net paper machine, a rotary paper machine, a tilt type paper machine, and a hybrid paper machine obtained by combining the same. In the case of production by a hybrid paper machine, the slurry having different blending ratios can be formed into a sheet and integrated to obtain a composite sheet formed of a plurality of paper layers. When performing papermaking, an additive such as a dispersibility improving agent, an antifoaming agent, or a paper strength enhancer may be used if necessary.

Further, other fibrous components (for example, polyarylene fiber, polyphenylene sulfide fiber, polyetheretherketone fiber, cellulose fiber, PVA fiber, polyester may be added). Organic fibers such as fibers, arylate fibers, liquid crystal polyester fibers, polyethylene naphthalate fibers, inorganic fibers such as glass fibers, rock wool, asbestos, and boron fibers glass fiber).

In the heat-resistant electrically insulating sheet of the present invention, since the polyarylamine fibrid is an adhesive having excellent characteristics, it can effectively complement the fine particles and other additive components; and the heat-resistant electrical insulating sheet of the present invention In the material manufacturing, not only the yield of the raw material can be improved, but also the lamination can be layered in the sheet, and the through hole can be reduced, thereby improving the electrical insulation.

The heat-resistant electrically insulating sheet obtained in this manner is hot-pressed at a high temperature and a high pressure between a pair of flat plates or a metal drum, whereby density and mechanical strength can be improved. In the case of using a metal drum, the conditions of the hot pressing are exemplified by a temperature of 100 to 350 ° C and a linear pressure of 50 to 400 kg/cm, but the invention is not limited thereto. The heating operation may be omitted, and only the normal temperature is applied. A plurality of heat-resistant electrically insulating sheets may be stacked during hot pressing. The above hot press processing can also be performed multiple times in any order.

The invention is illustrated by the following examples. Further, these examples are for illustrating the contents of the present invention without any limitation on the contents of the present invention.

Example

(Measurement methods)

(1) Measurement of particle size distribution

The particle size distribution was measured by a light scattering type particle size distribution measuring instrument (manufactured by Horiba, Ltd., laser diffraction/scattering type particle size distribution device LA-910).

(2) Weighted average of fiber length

A weighted average of the fiber lengths was measured with about 4,000 particles using a Fiber Quality Analyzer manufactured by Op Test Equipment.

(3) Measurement of basis weight and thickness

According to JIS C2300-2.

Regarding the difference in thickness, the thickness of 40 consecutive points was measured, and the standard deviation was used as the thickness difference.

(4) Calculation of density

Calculated by basis weight ÷ thickness.

(5) Measurement of tensile strength

The TENSILON tensile tester was operated under the conditions of a width of 15 mm, a collet interval of 50 mm, and a tensile speed of 50 mm/min.

(6) Air permeability

The time (seconds) at which 100 cc (0.1 dm ³ ) of air was transmitted through a sample sheet (area 642 mm ² ) was measured using a GURLEY type gas permeability test apparatus prescribed in JIS P8117, wherein the sample sheet was pressed with an outer diameter of 28.6. The platen of the round hole of mm.

(Material preparation 1)

A fiber-making device for producing pulp particles (wet-precipitation device) comprising a combination of a stator and a rotor in the Japanese Patent Laid-Open Publication No. Sho 52-15621 is used to produce a fiber of poly(phenylphenylisophthalamide). Strip. The treatment was carried out by a decomposition apparatus and a beating apparatus, and the weighted average value of the fiber length was adjusted to 0.9 mm (the freeness of the polyarylamine fibrids: 100 ml (Canadian freeness)).

On the other hand, a meta-aramid fiber (NOMEX (registered trademark), single-strand denier 2 Danny) manufactured by Dubai Company was cut into a length of 6 mm (hereinafter referred to as "melamine short fiber").

(Manufacture of polyarsenide paper by calendering)

The prepared polyarylamine fibrids and polyarylamine short fibers were separately dispersed in water to prepare a slurry. The blending ratio (weight ratio) of the fibrids and the polyamidamine short fibers was 1/1, and a sheet was formed by a TAPPI-type hand-made papermaking apparatus (cross-sectional area: 625 cm ² ). Next, the sheet-like material was subjected to hot press processing at a temperature of 330 ° C and a linear pressure of 300 kg/cm by a metal calender roll to obtain a calendered polyaramide paper.

(Material Preparation 2)

The material was prepared in the following manner: the above-mentioned calendered polyaramide paper was pulverized by a paper shredder and passed through a sieve having a pore size of 1 mm (hereinafter referred to as Φ1 polyamidamine paper) (weighting of fiber length) The average value is approximately 80% of the nozzle diameter).

The mixture was mixed with the above-mentioned Φ1 polyamidamine paper in an amount of 8 parts by mass and water in an amount of 92 parts by mass, and was shown in Table 1 by a high-pressure homogenizer (STAR BURST100 HJP-25080 manufactured by Sugino Machine Co., Ltd.: nozzle diameter: 0.5 mm). Under high pressure jet treatment, and make it hit The impact is broken by a hard object (ceramic) to form a raw material for papermaking.

(Examples 1 to 3, Comparative Examples)

(Manufacture of heat-resistant electrical insulating sheet)

The prepared Φ1 polyarsenamide paper, the prepared raw material for papermaking, and the prepared polyamidamine fibrids were respectively dispersed in water to prepare a slurry. The slurry was mixed at a blending ratio (mass ratio) shown in Table 1, and formed into a sheet by a TAPPI hand-held paper machine (sectional area: 625 cm ² ). Then, the sheet-like object was subjected to hot press processing under the conditions of a temperature of 330 ° C and a linear pressure of 300 kg/cm by a metal calender roll to obtain a heat-resistant electrically insulating sheet. The main characteristic values of the heat-resistant electrically insulating sheet obtained in this manner are shown in Table 1.

From the results of Table 1, it is understood that the heat-resistant electrically insulating sheets of the present invention (Examples 1 to 3) maintain a weighted average of the fiber lengths before the high-pressure jet treatment (Comparative Example), and Ju Fang Since the melamine short fiber component was hardly cut off, the strength was high and the thickness difference was small. Further, no change in appearance was observed even after the treatment at 250 ° C for 10 minutes, so that it could be used as a heat-resistant electrical insulating sheet. Moreover, it is considered that the addition of a component (corresponding to a particle diameter peak 1) of a polyarsenamide short fiber having a length of 0.3 to 0.4 mm causes a decrease in air permeability and generation of fine unevenness on the surface, and other When the sheet, the resin, and the like are bonded, the bonding area is widened, so that it is particularly useful as a A heat-resistant electrically insulating sheet used for a laminate of a film and an insulating resin.

Claims (5)

A method for producing a raw material for papermaking, which comprises a polyarsenide paper obtained by calendering a fibrid, a short fiber or a mixture thereof formed of an aromatic polyamine. In order to make the volume average particle size distribution of the polyamidamide paper which is fragmented by the high-pressure jet treatment, the peak of the particle diameter is in the range of 10 μm or more and less than 100 μm, and is subjected to high-pressure jet treatment to be broken into The constituent material of polyarsenamide paper. A method for producing a raw material for papermaking, which comprises a polyarsenide paper obtained by calendering a fibrid, a short fiber or a mixture thereof formed of an aromatic polyamine. In order to pulverize it before the high-pressure jet treatment, the particle diameter peaks in the volume average particle size distribution of the obtained pulverized polyamidamide paper are respectively in the range of 10 μm or more, less than 100 μm, and 100 μm or more and less than 1000 μm; After the high-pressure jet treatment of the pulverized polyamidamide paper, the peak frequency of the particle diameter in the range of less than 10 um and less than 100 um is increased, and the peak frequency of the particle diameter of 100 um or more and less than 1000 um is reduced, and high-pressure jetting is performed. It is processed to break it into a constituent material of polyarsenamide paper. The manufacturing method of claim 2, wherein the constituent material of the polyamimidamide paper before the high-pressure jet treatment has an average fiber length of the constituent material of the fragmented polyamidamide paper after the high-pressure jet treatment The retention rate is 80% or more. A raw material for papermaking, which is produced by the production method according to any one of claims 1 to 3. A heat resistant electrical insulating sheet characterized by: Contains raw materials for papermaking in item 4 of the patent application.