TW201320107A - Aramid-polyolefin laminate - Google Patents

Abstract

The present invention relates to a novel aramid-polyolefin laminate which has excellent mechanical characteristics, electrical insulating properties, dielectric characteristics, liquid impregnation properties and the like and is suitable for use as an insulating member for superconducting devices that are used at low temperatures. This aramid-polyolefin laminate is characterized by being formed into a laminate structure that contains a polyolefin in the form of layers in a layer of aramid paper which is formed of aramid fibrids and aramid short fibers and by having an air permeability of 10,000 seconds or more, said aramid-polyolefin laminate being also characterized in that at least a surface of the layer of aramid paper in contact with the polyolefin layer is impregnated with the polyolefin.

Description

Aromatic polyamine-polyolefin laminate

The present invention relates to a novel aromatic aramide-polyolefin laminate which is excellent in mechanical properties, electrical insulation properties, dielectric properties, liquid impregnation properties, etc., and can be preferably used as a low temperature. Insulating member of superconducting equipment.

It has been 25 years since the discovery of high-temperature superconductivity in 1986. In recent years, with the increase in power demand, in addition to the use of natural energy such as solar power, wind power, and hydropower, generators, motors, transformers, current limiters, Power cables and the like are being highly efficient, large-capacity, and miniaturized by high-temperature superconducting technology. As an insulating member used in such a superconducting device, for example, as shown in Japanese Laid-Open Patent Publication No. 2011-71129, a cowhide insulating paper, a polypropylene laminated insulating paper (PPLP), etc. are in an attempt to verify the practicality. However, since kraft paper is used, the dielectric constant and the dielectric loss tangent become high, and it is not always sufficient to cope with the increasing efficiency, large capacity, and miniaturization of superconducting equipment in recent years.

Insulation papers for superconducting devices such as generators, motors, transformers, current limiters, and power cables that require high efficiency and large capacity must meet the following four characteristics: 1) Low dielectric constant and dielectric loss tangent (low Dielectric); 2) higher withstand voltage; 3) with mechanical strength; and 4) fully impregnated with liquid nitrogen and other coolants.

It is considered that it is extremely important to maintain the superconducting state in the case where the above four characteristics are satisfied particularly in a low temperature state.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2011-71129

It is an object of the present invention to provide a low dielectric insulating paper which can withstand the high efficiency and large capacity of a superconducting device.

In view of the above, the inventors of the present invention have diligently studied to develop a low dielectric insulating paper which can withstand the high efficiency and large capacity of a superconducting device, and have completed the present invention.

In a first aspect, the present invention provides an aromatic polyamine-polyolefin laminate, which is formed by an aromatic group comprising an aromatic polyamine fibrid and an aromatic polyamide short fiber. The layer of the polyamide paper has a layered structure containing a polyolefin in a layer form, and at least the surface of the layer of the aromatic polyamide paper which is in contact with the polyolefin layer is impregnated with polyolefin, and the gas permeability is 10,000 seconds or more.

In a second aspect, the present invention provides an aromatic polyamine-polyolefin laminate according to the first aspect, wherein the layer of the polyolefin is a polyethylene, polypropylene or ethylene propylene copolymer.

In a third aspect, the present invention provides an aromatic polyamine-polyolefin laminate according to the first aspect or the second aspect, wherein a dielectric constant of -70 ° C and The increase in electrical loss tangent relative to the measured frequency shows a tendency to decrease.

In the fourth aspect, the present invention provides the aromatic polyamine-polyolefin laminate according to any one of the first to third aspects, wherein the layer of the aromatic polyamide paper has a void ratio of 50% or more.

In a fifth aspect, the present invention provides a superconducting device characterized in that an aromatic polyamine-polyolefin laminate according to any one of the first to fourth aspects is used as an insulating member.

In a sixth aspect, the present invention provides a superconducting power generator characterized in that an aromatic polyamine-polyolefin laminate according to any one of the first to fourth aspects is used as an insulating member.

In a seventh aspect, the present invention provides a superconducting motor characterized in that an aromatic polyamine-polyolefin laminate according to any one of the first to fourth aspects is used as an insulating member.

In the eighth aspect, the present invention provides a superconducting transformer characterized in that an aromatic polyamine-polyolefin laminate according to any one of the first to fourth aspects is used as an insulating member.

In a ninth aspect, the present invention provides a superconducting current limiter characterized in that an aromatic polyamine-polyolefin laminate according to any one of the first to fourth aspects is used as an insulating member.

In a tenth aspect, the present invention provides a superconducting cable characterized in that an aromatic polyamine-polyolefin laminate according to any one of the first to fourth aspects is used as an insulating member.

(aromatic polyamide)

In the present invention, the aromatic polyamine refers to a linear polyamide compound in which more than 60% of the guanamine bond is directly bonded to the aromatic ring. Examples of such an aromatic polyamine include poly(m-xylylenediphenyl) m-phenylenediamine and a copolymer thereof, polyparaphenylene terephthalamide and a copolymer thereof, and poly(p-phenylene)-( 3,4'-diphenyl ether) p-xylyleneamine copolymer and the like. These aromatic polyamines are industrially produced by, for example, a previously known interfacial polymerization method or solution polymerization method using meta-xylylene chloride and m-phenylenediamine, and are commercially available, but It is not limited to this. Among these aromatic polyamines, polym-xylylene m-phenylenediamine is preferably used in terms of characteristics such as good moldability, thermal adhesion, flame retardancy, and heat resistance.

(aromatic polyamine fibrid)

In the present invention, the aromatic polyamine fibrid system refers to a film-like aromatic polyamidamide particle which is paper-like, and is also called an aromatic polyamine pulp (refer to Japanese Patent Publication No. Sho 35-11851, Japan). Patent Publication No. Sho 37-5732, etc.).

It is known that the aromatic polyamine fibrids are subjected to dissociation and beating treatment in the same manner as ordinary wood pulp, and are used as papermaking raw materials, and so-called beating treatment can be carried out in order to maintain the quality suitable for papermaking. The beating treatment can be carried out by a disc refiner, a beater, and other papermaking raw material processing equipment with mechanical cutting action. In this operation, the morphology change of the fibrid can be monitored by the filtration test method (freeness) specified in Japanese Industrial Standard P8121. In the present invention, the filtration degree of the aromatic polyamidamine fibrid after the beating treatment is preferably in the range of 10 cm ³ to 300 cm ³ (Canadian freeness (JISP8121)). . The fibrids having a degree of filtration greater than this range may have a reduced strength of the multi-heat electrical insulating sheet material formed therefrom. On the other hand, if a degree of filtration of less than 10 cm ^{3 is} to be obtained, the utilization efficiency of the mechanical power to be input is reduced in many cases, and the amount of treatment per unit time is reduced, and further, the fineness of the fibrids is excessive. This is easy to cause a reduction in the so-called adhesive function. Therefore, even if it is desired to obtain a water filtration of less than 10 cm ^{3 ,} it is not possible to identify a significant advantage.

(aromatic polyamide short fibers)

The aromatic polybenzamine staple fiber is obtained by cutting the fiber of the aromatic polyamine as a material, and examples of such a fiber include "Teijinconex (registered trademark)" of Teijin Co., Ltd. and "Nomex (of Dupont)". Obtained as a product name such as a registered trademark), but is not limited to these.

The length of the aromatic polyamide short fibers is usually 1 mm or more and less than 50 mm, preferably from 2 to 10 mm. If the length of the short fibers is less than 1 mm, the mechanical properties of the sheet material are lowered. On the other hand, those having a length of 50 mm or more are prone to "winding" and "system" when the aromatic polyimide paper is produced by the wet method. It is easy to cause defects.

(aromatic polyamide paper)

In the present invention, the aromatic polyamide paper refers to a sheet mainly comprising the above-mentioned aromatic polyamine fibrids and aromatic polyamine short fibers, and usually has a thickness in the range of 20 μm to 1000 μm. Further, the aromatic polyamide paper usually has a basis weight in the range of 10 g/m ² to 1000 g/m ² .

Aromatic polyamide paper is usually obtained by using the above aromatic polyamine fibrids The aromatic polyamine short fibers are mixed and then produced by a method of sheet formation. Specifically, for example, a method in which the above-mentioned aromatic polyamine fibrids and aromatic polyamine short fibers are dry-mixed, and a sheet is formed by a gas flow; and an aromatic polyamine fibrid and aroma are used. a method in which a polybenzamide short fiber is dispersed and mixed in a liquid medium, and then ejected onto a liquid-permeable support such as a web or a belt to form a sheet, and then the liquid is removed and dried; It is preferred to select a so-called wet papermaking method using water as a medium.

The wet papermaking method is generally a method of feeding an aqueous slurry containing at least a single or a mixture of an aromatic polyamine fibril and an aromatic polyamine short fiber to a paper machine for dispersion, followed by dehydration and extrusion. The water and the drying operation are wound in the form of a sheet. As the paper machine, a long-wire type paper machine, a rotary screen type paper machine, a tilt type paper machine, and a combination paper machine in which these are combined can be used. In the case of manufacturing by a combined paper machine, the slurry having different blending ratios can be formed into a sheet and combined to obtain a composite sheet comprising a plurality of layers of paper. Additives such as a dispersibility improver, an antifoaming agent, and a paper strength enhancer may be used for papermaking.

The aromatic polyamide paper obtained in the above manner can be increased in density and mechanical strength by hot pressing at a high temperature and a high pressure between a pair of rolls. The conditions of the hot pressing are, for example, in the case of using a metal roll, and the temperature is in the range of 100 to 350 ° C and the line pressure is in the range of 50 to 400 kg / cm, but is not limited thereto. A plurality of layers of aromatic polyamide paper may also be laminated during hot pressing. The above hot press processing may also be performed several times in any order.

(polyolefin)

In the present invention, the polyolefin is a polymer synthesized by using a simple olefin or an olefin as a monomer (unit molecule). For example, polyethylene is a polyolefin obtained by polymerizing ethylene. Examples of such a polyolefin include polyethylene and a copolymer thereof, polypropylene and a copolymer thereof, polybutene and a copolymer thereof, and an ethylene propylene copolymer. These polyolefins are industrially produced and can be obtained as a commercial product, but are not limited thereto. Among these polyolefins, polyethylene, polypropylene, and ethylene propylene copolymer are preferably used in terms of characteristics such as good moldability, thermal adhesion, and low dielectric properties.

(Aromatic polyamine-polyolefin laminate with a gas permeability of 10,000 seconds or more)

A method for forming an aromatic polyamine-polyolefin laminate having a gas permeability of at least 10,000 seconds or more of a polyolefin layer formed on the surface of the above-mentioned aromatic polyamide paper of the present invention, as long as aromatic polyfluorene The at least surface of the amine paper is melt-impregnated with a polyolefin, and any method can be used without particular limitation. For example, a method in which a film obtained by melt-forming a polyolefin film in advance and a weight of the above-mentioned aromatic polyamide paper are combined and heated and pressurized to melt-impregnate the polyolefin into an aromatic polyamide paper can be used; a method in which a polyolefin papermaking (mesh) is mixed with or recombined with an aromatic polyamide paper to heat and press, and the polyolefin is melt-impregnated in an aromatic polyamide paper; the polyolefin is melt-extruded A method of thermal fusion on an aromatic polyamide paper.

The number of layers of the laminate may be appropriately selected depending on the purpose and purpose of the laminate, but it is preferable to ensure that the layer of the aromatic polyimide paper is at least one layer to ensure the impregnation property of the coolant such as liquid nitrogen. For example, A three-layer laminate of a fragrant polyurethane paper and a polyolefin, a three-layer laminate of an aromatic polyamide paper, a polyolefin, and an aromatic polyamide paper, but is not limited thereto.

The thickness of the laminate can be appropriately selected depending on the use and purpose of the laminate, and if there is no problem in workability such as bending or curling, any thickness can be selected. In general, from the viewpoint of workability, the thickness is preferably in the range of 50 μm to 1000 μm, but is not limited thereto.

Hereinafter, the present invention will be described by way of examples. Further, the embodiments are intended to exemplify the contents of the present invention, and are not intended to limit the scope of the present invention.

[Examples] (test methods)

(1) Length-weighted average fiber length

The length-weighted average fiber length of about 4000 particles was measured using a Fiber Quality Analyzer manufactured by Op Test Equipment.

(2) Determination of basis weight and thickness

Implemented in accordance with JIS C2300-2.

(3) Calculation of density

Calculated by basis weight ÷ thickness.

(4) Calculation of void ratio

The true specific gravity of the aromatic polyamine, polypropylene, and cowhide (cellulose) was calculated to be 1.38, 0.90, and 1.50, respectively.

(5) Determination of tensile strength

The Tensilon tensile tester was set to have a width of 15 mm, a collet interval of 50 mm, and a tensile speed of 50 mm/min.

(6) Dielectric coefficient, dielectric loss tangent

Implemented in accordance with JIS K6911.

(7) Insulation breakdown voltage

According to ASTM D149, the electrode diameter of 51 mm was carried out by the direct voltage boosting method of AC.

(8) Gurley permeability

The time of passing 100 cc (0.1 dm ³ ) of air through a sheet sample (area 642 mm ² ) pressed by a fixed plate having a circular hole of 28.6 mm was measured using a Gurley gas permeability measuring instrument specified in JIS P8117 ( second).

(Examples, Comparative Examples) (raw material preparation)

A sliver of poly(m-xylylenediphenyl) m-phenylenediamine is produced by using a device for producing pulp particles (wet precipitator) comprising a combination of a stator and a rotor described in Japanese Laid-Open Patent Publication No. SHO52-15621 . It was treated with a disintegrator and a beater to adjust its length-weighted average fiber length to 0.9 mm. The obtained aromatic polyamine fibrid has a water filtration of 90 cm ³ .

On the other hand, a meta-aramid fiber (Nomex (registered trademark), single yarn denier 2 Danny) manufactured by Dupont Co., Ltd. was cut into a length of 6 mm (hereinafter referred to as "aromatic polyamide short fiber"). .

(Manufacture of Aromatic Polyamide Paper)

The prepared aromatic polyamine fibrids and aromatic polyamine short fibers were each dispersed in water to prepare a slurry. The slurry was mixed in such a manner that the fibrids and the aromatic polyamide short fibers were blended at a ratio of 1/1 (weight ratio), and a sheet was formed using a Tappi type hand-laid machine (cross-sectional area: 625 cm ² ). To obtain an aromatic polyimide paper having a thickness of 144 μm. The main characteristic values of the aromatic polyamide paper obtained in this manner are shown in Table 1 as a comparative example.

(Manufacture of aromatic polyamine-polyolefin laminate)

The above-mentioned aromatic polyamide paper was superposed on each of a polypropylene film (Alphan E-201F, thickness: 50 μm) manufactured by Oji Paper Co., Ltd., and pressed at a temperature of 180 and a pressure of 17 g/cm ² for 10 minutes. Aromatic polyamine-polyolefin laminate. The main characteristic values of the aromatic polyamine-polyolefin laminate obtained in this manner are shown in Table 1.

It is considered that the aromatic polyamine-polyolefin laminate of the examples has a low dielectric constant and dielectric loss tangent, and the dielectric breakdown voltage and gas permeability are sufficiently high and the strength is high, and further, the aromatic poly group used. The porosity of the amide paper is high, and the porosity of the laminate is also high, and the impregnation property of the coolant such as liquid nitrogen is also high. Therefore, it is a low dielectric which can withstand the high efficiency and large capacity of the superconducting device. Insulation paper is more useful. Further, the frequency becomes higher at -70 ° C, and the dielectric constant and the dielectric loss tangent show a tendency to further decrease. Therefore, a superconducting device such as a superconducting motor that operates in a high-frequency inverter as a low-temperature high-frequency standard is used. Low dielectric insulation paper is especially useful.

(Comparative Examples 1 and 2) (Manufacture of cowhide-polyolefin laminate)

The kraft paper shown in Comparative Example 1 was placed one on each of the above polypropylene films, and pressed at a temperature of 180 and a pressure of 17 g/cm ² for 10 minutes to obtain a cowhide-polyolefin laminate. The main characteristic values of the cowhide-polyolefin laminate obtained in this manner are shown in Table 2.

It is generally considered that the dielectric coefficient of the cowhide-polyolefin laminate of Comparative Example 2 is Since the electric loss tangent is high, it is not sufficient as a low dielectric electrical insulating paper which can withstand the high efficiency and large capacity of the superconducting device.

Claims (10)

An aromatic polyamine-polyolefin laminate characterized in that it is formed in a layer on a layer of an aromatic polyamide paper comprising an aromatic polyamine fibrid and an aromatic polyamide short fiber. In the layered structure containing polyolefin, at least the surface of the layer of the aromatic polyamide paper which is in contact with the polyolefin layer is impregnated with polyolefin, and the gas permeability is 10,000 seconds or more. The aromatic polyamine-polyolefin laminate according to claim 1, wherein the layer of the above polyolefin is a polyethylene, polypropylene or ethylene propylene copolymer. The aromatic polyamine-polyolefin laminate according to claim 1 or 2, wherein a dielectric constant of -70 ° C and a dielectric loss tangent show a tendency to decrease with respect to an increase in the measurement frequency. The aromatic polyamine-polyolefin laminate according to claim 1 or 2, wherein the layer of the aromatic polyamide paper has a void ratio of 50% or more. A superconducting device characterized by using the aromatic polyamine-polyolefin laminate according to any one of claims 1 to 4 as an insulating member. A superconducting power generator using the aromatic polyamide-polyolefin laminate according to any one of claims 1 to 4 as an insulating member. A superconducting motor characterized by using the aromatic polyamine-polyolefin laminate according to any one of claims 1 to 4 as an insulating member. A superconducting transformer characterized by using the aromatic polyamine-polyolefin laminate according to any one of claims 1 to 4 as an insulating member. A superconducting current limiter characterized by using the aromatic polyamine-polyolefin laminate according to any one of claims 1 to 4 as an insulating member. A superconducting cable characterized by using the aromatic polyamine-polyolefin laminate according to any one of claims 1 to 4 as an insulating member.