JPS6024878B2 - sheet - Google Patents

Description

[Detailed description of the invention] The present invention relates to sheets.

More specifically, the present invention relates to a dew-proofing paper that is excellent in yield rate, dielectric support, impregnability, mechanical properties, etc., particularly a sheet related to electrical insulation-proofing paper for high-voltage power transmission cables. A feature of the present invention is that polypropylene short fibers and a polycarbonate pulp material are mixed in a specific ratio to make paper, and then heated and pressurized after drying. Conventionally, natural pulp is the most well-known pulp particle used in paper, and paper made from natural pulp is often used as cutting paper for power transmission cables.

However, since the main chemical component of paper made from natural pulp is cellulose, it has poor dielectric properties and heat resistance, and in recent years, paper made from natural pulp has been studied in order to meet the increasing demand for electricity. It is said that it can hardly be used as an absolute quadrant for power transmission cables of 500 KV or more.

Recently, polycarbonate, polyprolene, polyethylene,
Polyphenylene oxide, polysulfone, poly(26
- Diphenyluparaphenylene oxide) and other materials are being considered.

It is well known that the dielectric properties of these materials are sufficient to serve the purpose of woven paper for power transmission cables of 500 KV or higher, that is, to reduce electrostatic loss. For example, in Japanese Patent Publication No. 48-23961, we previously used short polycarbonate fibers {a) and a solution of polycarbonate dissolved in a halogenated hydrocarbon having a boiling point of 90% or less at a concentration of 2 to 2% by weight. A pulp-like material 'b- obtained by injecting or injecting it into hot water maintained at a temperature higher than the boiling point of the halogenated hydrocarbon.
We have proposed a method for producing polycarbonate paper, which is characterized in that a sheet is prepared by mixing in a ratio of 1:2 to 5:1 (weight ratio), and the sheet is heated and pressurized at a temperature of 140 to 170°C. Although the dielectric properties of the polycarbonate paper obtained by this method were very excellent, it also had the following drawbacks.

[11] Mechanical properties, especially low tensile strength.

[2' Perhaps because of the poor shape of the pulp-like material produced by the above method, it was difficult to continuously produce the paper using a paper machine.

Since halogenated hydrocarbons, which are slightly miscible with tide water, are used as solvents, it is difficult to remove the halogenated hydrocarbons that remain in the pulp-like material.

Furthermore, Japanese Patent Publication No. 48-26801 discloses a dimethyl-formamide solution of polycarbonate and polyester,
The mixture with short fibers is formed into a thin film, this thin film is immersed in water to form a sheet consisting of a precipitated polymer matrix and the short fibers contained therein, and then rolled with a calendar roll under heat and pressure. A method of manufacturing synthetic paper passed through military stunning material is described in Z.

Although the dielectric properties of the synthetic paper obtained by this method are excellent, it is difficult to uniformly mix the short fibers into the polymer solution, and there are some thickness and thin spots, making it difficult to obtain a uniform paper. It is. It has drawbacks such as: In order to eliminate these drawbacks, we have made the following findings as a result of intensive studies and have completed the present invention. '1' polycarbonate dissolves well in N-methyl-2-pyrrolidone, which is miscible with water, and the stability of the solution is good.

'2' By introducing the solution into a precipitating agent consisting of N-methyl-2-pyrrolidone and water and precipitating it as fine particles, a pulp-like material with good shape is obtained.

[31] This pulp-like material has good paper-making properties, and there are no problems such as paper breakage when it is mixed with short fibers and continuously produced, for example, in a Fourdrinier paper machine.

The properties of the sheet obtained by using a specific proportion of polypropylene short fibers as the short fibers in t4' (section 3') were satisfactory in terms of not only dielectric properties but also mechanical properties and impregnation properties.

That is, the present invention combines 10 to 9% by weight of short polypropylene fibers {a} and polycarbonate with N-methyl-2
A pulp-like material obtained by introducing a solution dissolved in pyrrolidone into a precipitant consisting of N-methyl-2-pyrrolidone and water and 90 to 90% by weight of the material is mixed to make paper, dried, and then heated and pressurized. This is a sheet.

In the present invention, the polycarbonate refers to bis(4-hydroxyphenyl)methane, 1.1-bis(4-hydroxyphenyl)ethane, bis(4-hydroxyphenyl)propane, bis(4...hydroxy-3 .5-dichlorophenyl)methane, pis(4-hydroxyphenyl)phenylmethane, 2.2-bis(4-hydroxy-3
．． It is obtained by using 5-dibromophenyl) propawa as a dioxy component and reacting it with phosgene or diphenyl carbonate.

This is the so-called phosgene method polycarbonate or ester exchange method polycarbonate, and its average molecular weight is 10.
000-5,00 government order or 20,000-35,00
It is 00. In producing the pulp-like material used in the present invention, a solution of polycarbonate in N-methyl-2-pyrrolidone is introduced into a precipitant consisting of water and N-methyl-2-pyrrolidone, and the pulp-like material is precipitated as fine particles. Apply to matter and what it does. The concentration of polycarbonate in the N-methyl-2-pyrrolidone solution of polycarbonate varies depending on the degree of polymerization, type, etc. of the polycarbonate, but is preferably approximately 2 to 2% by weight, and more preferably 6 to 1% by weight.

The temperature of the solution during precipitation is 10 to 90 qo, particularly preferably 20 to 60 qo. Moreover, there is no problem even if a small amount of water is contained in the solution. Furthermore, it is not necessary to add and mix into the solution a minute solid inorganic substance that does not substantially react with or dissolve in the solution, but it can further improve impregnating properties, heat resistance, electrical insulation properties, and paper-making properties. The above is preferable. In this case, as the solid inorganic substance, one or more of micas, asvert, glass flakes, quartz powder, talcum kaolin, alumina, etc. can be used.

When a solid inorganic substance is mixed, the amount should be 5 to 4 times the amount of the polymer.
0% by weight, preferably 10-20% by weight. When mixing the solid inorganic substance described above into a solution, it is preferable to disperse it as uniformly as possible.
K. Homo Mixer (manufactured by Tokushu Kika Kogyo), Attritor (manufactured by Mitsui, Miike Seisakusho), etc. are effective.

Next, in the present invention, a precipitant consisting of water and N-methyl-2-pyrrolidone is used as a precipitant when producing a pulp-like material.

The concentration of N-methyl-2-pyrrolidone in the precipitant varies somewhat depending on the type of polymer, polymer concentration, degree of polymerization, etc., but is suitably 15 to 8% by weight, preferably 30 to 7% by weight.

If the content is greater than 8% by weight, the produced pulp-like substances will aggregate and weld together, resulting in a decrease in tensile strength and elongation and dielectric breakdown voltage of the sheet obtained by processing this pulp-like substance.

On the other hand, if it is less than 15% by weight, the shape of the resulting pulp-like material becomes coarse, and the entanglement of the pulp-like materials with each other and the entanglement of the pulp-like material with short fibers decreases.
In addition to poor paper-making properties, the mechanical properties and dielectric breakdown voltage of the resulting sheet also deteriorate. The temperature of the precipitating agent during precipitation is 10 to 70°C, preferably 20 to 50°C. The precipitant is operated at high speed to remove soot from the introduced solution and at the same time produce a chick cutting or beating action. The precipitant/solution flow rate ratio is desirably 5/1 to 30/1, particularly preferably 8/1 to 15/1.

(Weight ratio) The pulp-like material thus obtained is thoroughly washed with water by a known method, mixed with polypropylene staple fibers, and then dried and heated and pressed to form an excellent sheet.

At this time, the ratio of pulp-like material/polypropylene short fibers in the sheet needs to be 90/1 to 10/90 by weight.

If the amount of pulp-like material is more than 9% by weight, the mechanical properties, especially the tensile elongation, will be low and the soakability will be poor.

Conversely, if the amount of pulp-like material is less than 1% by weight, the mechanical properties and dielectric breakdown voltage of the sheet will decrease. It is best to make paper from pulp-like substances and short polypropylene fibers using a wet process using a remeshing or circular-type papermaking machine, as in the case of papermaking from conventional natural pulp. A surfactant, a polyether, a dispersant such as root juice of A. japonica, and a thickener may also be added. Generally commercially available short polypropylene fibers can be used.

After the sheet obtained as described above is dried, it is heated under pressure using a heat press or a heat roll.
Demonstrates excellent performance.

The temperature at the time of pressurization varies somewhat depending on the amount of pulp-like material in the sheet, etc., but an appropriate temperature is 70 to 18,000.

The pressure, like the temperature, varies depending on the amount of pulp-like material in the sheet, etc., but is preferably 400 k9/min or less.

The method for measuring the main measured values in the present invention will be explained below.

Tensile strength: kg according to JISP8118 method
/ side 2.

Tensile elongation: Measured according to the method of JISP8132 and expressed in %.

Dielectric breakdown voltage: Measured using AC voltage according to the method of JISC2111.

Dielectric constant, dielectric loss tangent: 20 according to JISC2111 method
Measured at 6°C/S.

Impregnating property: A sample cut into a disk shape with a diameter of 1 shipboard was measured according to JISI
The sample was floated on the surface of No. 1 insulating oil, and the time required for the insulating oil to penetrate the entire surface was measured, and the time was divided by the thickness of the sample and expressed as Sec/skin.

Example 1 Preparation of polymer solution One box part by weight of poly-4,4-dioxydiphenyl-2,2-propane carbonate powder was poured into 80 parts by weight of NMP with a moisture content of 0.2% by weight. After that, 60
The polymer was completely dissolved by flooding to 0.0°C.

Next, the temperature of the solution was cooled to 30 qo to prepare a solution for producing a pulp-like material. 6 parts by weight of NMP and 33 parts by weight of water were mixed to prepare a precipitant.

A conduit-type continuous sedimentation machine consisting of a combination of a stator with a weighted buffer of pulp-like material and a turbine blade-shaped rotor, and equipped with an inlet for a precipitant, a solution, and an outlet for a slurry of pulp-like material after precipitation. The solution was simultaneously fed into the machine at a flow rate of 0.5 k9/min and the precipitant was fed at a flow rate of 5 k9/min, and the pulp-like material slurry was taken out from the outlet.

At this time, the temperature of the precipitant was adjusted to 370°C, and the temperature of the solution was adjusted to 30°C.

Also, the rotation of the rotor is 7.10 times. r. m. And so. The resulting pulpy material slurry was placed in a Nutsche type vacuum sieve equipped with a 200-mesh stainless wire mesh to separate most of the precipitant as leakage.

Next, without taking out the pulp-like material from the transfer machine, ion-exchanged water was supplied in an amount equal to three times the amount of the pulp-like material (between molds), and the material was washed under reduced pressure.

Approximately four times the amount of water as the pulp-like material (solid content) was attached to the pulp-like material thus obtained.

When the NMP concentration in this adhered water was measured by gas chromatography, it was found that o. % by weight, and the cleaning was sufficient to the extent that there was no practical problem. The pulp-like material obtained by the papermaking method described above has a solid content of 1.2 mm (solid content) and a single yarn weave of 2
When paper was made from an aqueous dispersion containing polypropylene short fibers (manufactured by Mitsubishi Rayon, trade name: Pyren) with a denier of 6 and a fiber length of 0.8 mm using a Tatsupi standard sheet machine, the paper-making properties were good and the texture was good. Got a sheet.

After drying this sheet, it was heat pressed in the first stage at 70℃ and 300 kg/base, then in the second stage under the conditions of 15 mm, 0,200 kg/base, and the thickness of the paper was approximately 145 mm. I got it. The tensile strength of this paper was 4.7k9/fence 2, the density was 14.0%, the dielectric constant was 2.7, and the dielectric support was 0.05%.Also, the breaking strength was 12. Shoe V rib, impregnability is 190
It was on the ship ec/side.

Example 2 A pulp-like material was prepared in exactly the same manner as in Example 1, except that the polymerization degree concentration in the polymer solution was 9% by weight, and the NMP concentration in the precipitant was 4% by weight. Obtained.

Next, the performance of the obtained paper, which was carried out in the same manner as in Example 1, was almost the same as that of the paper obtained in Example 1 and was good. Further, the impregnation property of this paper was measured and was found to be good at 200 $ec/side. Example 3 In Example 1, the amounts of polycarbonate pulp-like material and polypropylene short fibers during paper manufacturing were varied to obtain sheets with various proportions of polycarbonate pulp-like material and polypropylene short fibers in the sheets. .

Table 1 shows the measurement results for these sheets. Table 1 In Table 1, M. Nos. 1, 2, 6, and 7 are examples in which the ratio of polycarbonate pulp-like material to polypropylene fiber in the sheet is outside the scope of the present invention. 1, 2,
Although the dielectric properties of No. 6 were excellent, the tensile strength and elongation were insufficient.

Also, lungs. In case No. 7, the wet paper could not be taken out from the paper-making wire mesh, and no sheet could be obtained.

On the other hand, the gunwale. Samples Nos. 3, 4, and 5 were obtained by the method of the present invention, and had satisfactory levels of both tensile strength and elongation and dielectric properties. Example 4 As a polycarbonate, a polycarbonate obtained by the phosgene method from 9 blade weights of bis(4-hydroxyphenyl)-propane and 7 weights of 2-2-bis(4-hydroxy-3.5-dibromoophenyl)propane was used. A pulp-like material was obtained by carrying out the same procedure as in Example 1 except that a polymer was used.

Claims (1)

[Claims] 1. A solution of (a) 10 to 90% by weight of short polypropylene fibers and (b) polycarbonate in N-methyl-2-pyrrolidone is introduced with stirring into a precipitant consisting of N-methyl-2-pyrrolidone and water. A sheet made by mixing 90 to 10% by weight of a pulp-like material obtained by the above method, drying, and heating under pressure.