Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J11/00—Recovery or working-up of waste materials
  • C08J11/04—Recovery or working-up of waste materials of polymers
  • C08J11/06—Recovery or working-up of waste materials of polymers without chemical reactions
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H13/00—Pulp or paper, comprising synthetic cellulose or non-cellulose fibres or web-forming material
  • D21H13/10—Organic non-cellulose fibres
  • D21H13/20—Organic non-cellulose fibres from macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H13/26—Polyamides; Polyimides
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
  • B29B17/00—Recovery of plastics or other constituents of waste material containing plastics
  • B29B17/04—Disintegrating plastics, e.g. by milling
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/12—Powdering or granulating
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H27/00—Special paper not otherwise provided for, e.g. made by multi-step processes
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21J—FIBREBOARD; MANUFACTURE OF ARTICLES FROM CELLULOSIC FIBROUS SUSPENSIONS OR FROM PAPIER-MACHE
  • D21J1/00—Fibreboard
  • D21J1/16—Special fibreboard
  • D21J1/20—Insulating board
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2377/00—Characterised by the use of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Derivatives of such polymers
  • C08J2377/06—Polyamides derived from polyamines and polycarboxylic acids
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W30/00—Technologies for solid waste management
  • Y02W30/50—Reuse, recycling or recovery technologies
  • Y02W30/62—Plastics recycling; Rubber recycling

Definitions

• the present invention relates to a method for recycling calendered aramid paper and a heat-resistant electrical insulating sheet material. More particularly, the present invention relates to a method for recycling calendered aramid paper that enables reuse of calendered aramid paper that has been incinerated or disposed of without using chemicals, and a heat-resistant electrical insulating sheet material. Is.
• Paper made from high performance materials has been developed to provide paper with improved strength and / or thermal stability.
• aramid paper is a synthetic paper made of aromatic polyamide. Due to its heat and flame resistance, electrical insulation, toughness and flexibility, the paper has been used as an electrical insulation material and a base for aircraft honeycombs.
• DuPont (USA) Nomex (R) fiber-containing paper mixes poly (metaphenylene isophthalamide) floc and fibrids in water and then mixes The slurry is made by paper making and calendering. This paper is known to still have high strength and toughness and excellent electrical insulation even at high temperatures.
• Aramid paper scraps and damaged materials are subjected to high-temperature and high-pressure treatment by calendering, so they are not defibrated at all with water alone. Therefore, it is incinerated or disposed of. Also, after being dissolved in an organic solvent, chemical recycling is carried out again to form paper-making raw materials such as flock, fibrid, and pulp as well as virgin raw materials, but this method requires environmental considerations. Yes, and the cost tends to increase.
• JP-A-4-228696 and JP-A-2003-290676 have been.
• actual aramid paper is mostly used after being calendered, it is difficult to say that these methods are practical.
• JP-A-7-243189 describes a porous aramid molded product using aramid paper pulp obtained by pulverizing aramid paper.
• the molded product is considered to have insufficient electrical insulation due to its porosity.
• An object of the present invention is to provide a heat-resistant electrical insulating sheet obtained by reusing calendered aramid paper without using a chemical solution or the like.
• the present invention provides a fine particle having a length-weighted average fiber length of 1 mm or less obtained by pulverizing calendered aramid paper, which is a synthetic paper made of aromatic polyamide, and aramid fibrids.
• a heat-resistant electrical insulating sheet material characterized by comprising:
• the present invention provides a finely pulverized aramid paper, which is a synthetic paper made of an aromatic polyamide, prepared by dry pulverization, and the prepared fine particles, aramid fibrid, and water are combined.
• a method for producing a heat-resistant electrical insulating sheet material characterized in that a mixed slurry is formed and paper is made using the formed slurry.
• aramid means a linear polymer compound (aromatic polyamide) in which 60% or more of amide bonds are directly bonded to an aromatic ring.
• aromatic polyamide examples include polymetaphenylene isophthalamide and copolymers thereof, polyparaphenylene terephthalamide and copolymers thereof, poly (paraphenylene) -copoly (3,4 diphenyl ether) terephthalamide, and the like.
• These aramids are industrially produced by, for example, conventionally known interfacial polymerization methods, solution polymerization methods and the like using isophthalic acid chloride and metaphenylenediamine, and can be obtained as commercial products. Is not to be done.
• polymetaphenylene isophthalamide is preferably used in that it has excellent molding processability, thermal adhesiveness, flame retardancy, heat resistance, and the like.
• aramid fibrids are film-form aramid particles having paper-making properties and are also called aramid pulp (see Japanese Patent Publication No. 35-11851, Japanese Patent Publication No. 37-5732, etc.).
• Aramid fibrids are widely known to be used as a papermaking raw material after being disaggregated and beaten in the same manner as ordinary wood pulp, and can be subjected to so-called beating treatment for the purpose of maintaining quality suitable for papermaking. This beating process can be performed by a paper refiner, a beater, or other papermaking raw material processing equipment that exerts a mechanical cutting action.
• the shape change of the fibrid can be monitored by the freeness test method stipulated in Japanese Industrial Standard P8121.
• the freeness of the aramid fibrid after the beating treatment is preferably in the range of 10 cm 3 to 300 cm 3 (Canadian Freeness).
• the strength of the multi-thermal electrical insulation sheet material formed therefrom may be reduced.
• the utilization efficiency of the mechanical power to be input becomes small, the processing amount per unit time is often reduced, and further, the fibrid is miniaturized. Since it proceeds too much, the so-called binder function is likely to be lowered. Therefore, even when trying to obtain a freeness smaller than 10 cm 3 in this way, no particular advantage is recognized.
• the aramid short fiber is obtained by cutting a fiber made of aramid.
• aramid a fiber made of aramid.
• examples of such a fiber include “Teijin Conex (registered trademark)” by Teijin Limited and “Nomex (registered trademark)” by DuPont.
• the length of the aramid short fibers can be selected from the range of generally 1 mm or more and less than 50 mm, preferably 2 to 10 mm. When the length of the short fiber is smaller than 1 mm, the mechanical properties of the sheet material are deteriorated. On the other hand, when the length is 50 mm or more, “entanglement”, “binding”, etc. are likely to occur in the production of aramid paper by the wet method. Prone to defects.
• the aramid paper is a sheet-like material mainly composed of the aramid fibrids and short aramid fibers, and generally has a thickness in the range of 20 ⁇ m to 1000 ⁇ m. Further, aramid paper generally has a basis weight in the range of 10 g / m 2 to 1000 g / m 2 .
• Aramid paper is generally produced by a method of mixing the above-mentioned aramid fibrid and aramid short fibers and then forming a sheet.
• a method of forming a sheet using an air flow after dry blending the aramid fibrid and the aramid short fiber, a method of forming a sheet using an air flow, after the aramid fibrid and the aramid short fiber are dispersed and mixed in a liquid medium, the liquid permeation is performed.
• a so-called wet papermaking method using water as a medium is preferably selected.
• a single or mixed aqueous slurry containing at least aramid fibrids and short aramid fibers is fed to a paper machine and dispersed, and then dewatered, squeezed and dried to be wound up as a sheet. The method is common.
• a long paper machine As the paper machine, a long paper machine, a circular paper machine, a slanted paper machine, and a combination paper machine combining these are used.
• a composite sheet composed of a plurality of paper layers can be obtained by forming and combining slurry having different blending ratios.
• Additives such as a dispersibility improver, an antifoaming agent, and a paper strength enhancer are used as necessary during papermaking.
• the aramid paper obtained as described above can be improved in density and mechanical strength by hot pressing at high temperature and high pressure between a pair of rolls.
• the hot pressure conditions include, but are not limited to, a temperature range of 100 to 350 ° C. and a linear pressure of 50 to 400 kg / cm when using a metal roll.
• a plurality of aramid papers can be laminated during hot pressing. The above hot pressing can be performed a plurality of times in an arbitrary order.
• the fine particles used in the present invention preferably have a length-weighted average fiber length of 1 mm or less as measured with an optical fiber length measuring device after pulverizing the calendared aramid paper.
• an optical fiber length measuring device measuring equipment such as Fiber Quality Analyzer (manufactured by Op Test Equipment), Kayani type measuring device (manufactured by Kayani) can be used. In such an instrument, the fiber length and morphology of fine particles passing through a certain optical path are individually observed, and the measured fiber length is statistically processed.
• a method of pulverizing the calendared aramid paper a method of pulverizing and finely pulverizing by a dry method, a wet method or both means is preferable.
• the dry method is a method of using a shredder, a crusher, a kneader or the like, and impacting aramid paper without substantially interposing moisture to decompose it into fine particles.
• the wet method is a method of reducing the particle size by applying an impact to aramid paper in an aqueous medium.
• equipment for efficiently carrying out such wet pulverization include a high-speed disintegrator, a refiner, and a beater, but are not limited thereto.
• the dry method is used for pulverization, and then the wet method is used for the pulverization.
• Mixing with aramid fibrid facilitates homogenization of the liquid mixture and facilitates the production of homogeneous and fine particles, and at the same time, a single aramid fibrid that needs to be implemented for sheet manufacturing. It is also possible to omit the beating process.
• the heat-resistant electrical insulating sheet material of the present invention is a sheet-like material mainly composed of the fine particles and aramid fibrids, and generally has a thickness in the range of 20 ⁇ m to 5 mm. Further, the heat-resistant electrical insulating sheet material generally has a basis weight in the range of 10 g / m 2 to 5000 g / m 2 .
• the content of aramid fibrid in the heat-resistant electrical insulating sheet material is not particularly limited as long as the desired electrical insulation is achieved, but 5 to 80 in order to maintain the process strength during the production of the heat-resistant electrical insulating sheet material.
• the content of fine particles in the heat-resistant electrical insulating sheet material is preferably in the range of 20 to 95% by weight, but is not limited to this range, and is preferably 30% by weight or more from the viewpoint of recycling, and maintains the process strength. Therefore, it is more preferably in the range of 30 to 85% by weight, particularly preferably in the range of 50 to 85% by weight.
• the heat-resistant electrical insulating sheet material is generally produced by a method of mixing the above-described fine particles and aramid fibrid and then forming a sheet.
• a method of forming a sheet using an air stream after dry blending the fine particles and the aramid fibrid, and dispersing and mixing the fine particles and the aramid fibrid in a liquid medium, and then supporting the liquid permeability a method of discharging onto a body, for example, a net or a belt, forming a sheet, and drying after removing the liquid can be applied.
• a so-called wet papermaking method using water as a medium is preferably selected.
• the wet papermaking method there is a method in which a single or mixture aqueous slurry containing at least fine particles and aramid fibrid is fed to a paper machine and dispersed, and then dewatered, squeezed, and dried to be wound up as a sheet. It is common.
• a paper machine a long paper machine, a circular paper machine, a slanted paper machine, and a combination paper machine combining these are used.
• a composite sheet composed of a plurality of paper layers can be obtained by forming and combining slurry having different blending ratios.
• Additives such as a dispersibility improver, an antifoaming agent, and a paper strength enhancer are used as necessary during papermaking.
• the tensile strength can be further increased by adding aramid short fibers to the heat-resistant electrical insulating sheet material.
• the content of aramid short fibers in the heat-resistant electrical insulating sheet material is preferably in the range of 5 to 50% by weight, but is not limited to this range. In order to keep it, the range of 5 to 30% by weight is particularly preferred.
• the heat-resistant electrical insulating sheet material thus obtained can be improved in density and mechanical strength by hot pressing at a high temperature and high pressure between a pair of flat plates or between metal rolls.
• conditions for the hot pressure include, but are not limited to, a temperature of 100 to 350 ° C. and a linear pressure of 50 to 400 kg / cm when a metal roll is used. It is also possible to simply press at room temperature without adding a heating operation.
• a plurality of heat-resistant electrical insulating sheet materials can be laminated during hot pressing. The above hot pressing can be performed a plurality of times in an arbitrary order.
• Measurement of basic weight and thickness It implemented according to JIS C2111.
• Calculation of density It calculated with basic weight ⁇ thickness.
• Length Weighted Average Fiber Length Using a Fiber Quality Analyzer manufactured by Op Test Equipment, the length weighted average fiber length of about 4000 fine particles was measured.
• Measurement of tensile strength A Tensilon tensile tester was carried out at a width of 15 mm, a chuck interval of 50 mm, and a tensile speed of 50 mm / min.
• Dielectric breakdown voltage According to ASTM D149, an electrode diameter of 51 mm was used by a direct voltage boosting method using alternating current.
• a polymetaphenylene isophthalamide fibrid was manufactured using a pulp particle manufacturing apparatus (wet precipitator) composed of a combination of a stator and a rotor described in JP-A-52-15621. This was processed with a disaggregator and a beater to adjust the length weighted average fiber length to 0.9 mm.
• a meta-aramid fiber Nomex (registered trademark), single yarn fineness 2 denier) manufactured by DuPont was cut into a length of 6 mm (hereinafter referred to as “aramid short fiber”) to obtain a raw material for papermaking.
• the prepared aramid fibrids and aramid short fibers were each dispersed in water to form a slurry. These slurries were mixed so that the fibrid and the aramid short fiber had a blending ratio (weight ratio) of 1/1, and a sheet-like material was produced with a tappy type hand machine (cross-sectional area 625 cm 2 ). . Next, this was hot-pressed with a metal calender roll at a temperature of 330 ° C. and a linear pressure of 300 kg / cm to obtain calendered aramid paper.
• Examples 1 to 3 and a control example (Fine particle raw material preparation)
• the calendared aramid paper was pulverized with a dry pulverizer.
• a slurry mixed with water having passed through a sieve having an aperture diameter of 3 mm and water was prepared, and this slurry was treated with a disaggregator and a beater to adjust the length-weighted average fiber length to the size shown in Table 1.
• the prepared fine particles, the prepared aramid fibrids, and the prepared aramid short fibers were each dispersed in water to prepare a slurry.
• the heat-resistant electrical insulating sheet materials of Examples 1 to 3 have a sufficiently high dielectric breakdown voltage, and further, no change was observed in the appearance even after treatment at 250 ° C. for 10 minutes, so that they are useful as heat-resistant electrical insulating sheet materials .
• Example 4 (Fine particle raw material preparation)
• the calendared aramid paper was pulverized with a dry pulverizer. Prepare a mixed slurry of aramid fibrid and water that has passed through a sieve with an aperture diameter of 3 mm, and treat this slurry with a disaggregator and a beater so that the length-weighted average fiber length is the size shown in Table 2. Adjusted. (Manufacture of heat-resistant electrical insulation sheet material) Fine particles prepared by pulverizing a mixture of aramid paper and aramid fibrid and aramid short fibers were dispersed in each water to prepare a slurry.
• the heat-resistant electrical insulating sheet material of Examples 4 to 6 was obtained by pulverizing a mixed slurry of fine particles and aramid fibrids, the raw material for fine particles and aramid fibrids were obtained in a shorter time than the heat-resistant electric insulating sheet materials of Examples 1 to 3. Has been prepared. Further, the characteristics were almost the same as or better than those of Examples 1 to 3.

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