JPS5911685B2 - Method for producing pulp-like material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a pulp-like material consisting of a wholly aromatic polyester.

More specifically, it has good paper-making properties and is useful for producing uniform sheet-like structures with excellent impregnation properties, electrical insulation properties, mechanical properties, heat resistance, flame retardance, and moisture absorption resistance, and good texture. This is a method for producing a pulp-like substance.

Conventionally, natural pulp is the most well-known pulp-like substance used for paper, and paper made from natural pulp is often used as electrically insulating paper. However, paper made from natural pulp has the major drawback of lacking heat resistance and flame retardancy, which is far from meeting the heat resistance and flame retardance required to make electrical equipment such as electric motors and transformers smaller and lighter. It is something. Furthermore, paper made from natural pulp has the disadvantage of being highly hygroscopic, and when used as electrically insulating paper, careful attention must be paid to drying to remove moisture and preventing moisture absorption after drying. is very troublesome. 5 Recently, pulp-like substances obtained from synthetic polymers have been attracting attention as materials for electrically insulating paper because of their excellent heat resistance and electrical insulation properties.

For example, Japanese Patent Publication No. 35-11851 describes a pulp-like material made of a synthetic polymer.
However, the pulp-like substances described above have poor paper-forming properties when wet-processed to produce paper.
It is difficult to obtain a uniform paper with good texture.Furthermore, when the pulp-like material is processed and used as electrically insulating paper, it also has the disadvantage that impregnating properties and electrically insulating properties are not sufficient. are doing. In order to eliminate the drawbacks of paper made from natural pulp and pulp-like materials made from synthetic fibers, the present inventors, as a result of intensive research, solved the problem by dissolving fully aromatic polyester in a specific fluorocarbon solvent and dissolving it under specific conditions. By introducing it into a precipitant that satisfies the above conditions and precipitating it as fine particles, a pulp-like material with a good shape as shown in Fig. 1 can be obtained, and furthermore, the pulp-like material has good paper-making properties. Even when mixed with staple fibers and continuously made into paper using the Fourdrinier paper machine 25, there are no problems such as paper breakage, and the sheets thus obtained are dried and heated under pressure. Book 3 found that the texture of the paper is perfect and has excellent electrical insulation, impregnation properties, mechanical properties, and flame retardancy.
0 invention has been completed.

That is, in the present invention, a solution in which a wholly aromatic polyester is dissolved in an amide solvent is mixed with an amide solvent and water,
This is a method for producing a pulp-like material, which is characterized in that an amide solvent is introduced into a precipitant having a concentration of 20 to 85% by weight while stirring, and precipitated as fine particles.

Totally aromatic polyester In the present invention, the wholly aromatic polyester is a polyester obtained by condensation polymerization of one or more aromatic dicarboxylic acids or functional derivatives thereof and one or more dihydroxy aromatic compounds. Alternatively, it is a polyester obtained by condensation polymerization of aromatic oxycarboxylic acids. Examples of aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, and the like.

In addition, examples of dihydroxy aromatic compounds include r, for example, 2,
2-bis(4-hydroxyphenyl)propane [bisphenol A], 1,1-bis(4-hydroxyphenyl)cyclohexane [bisphenol Z), L1-bis(
4-hydroxyphenyl)ethane, bis(4-hydroxyphenyl)methane, 1,2-bis(4-hydroxyphenyl)ethane, bis(4-hydroxyphenyl)cyclohexylmethane, 3,3-bis(4 -hydroxyphenyl)penone, bis(4-hydroxyphenyl)sulfone, bis(4-hydroxyphenyl)ether, hydroquinone, 4,4'-dihydroxybiphenyl, and the like. Also, aliphatic dihydroxy compounds such as glycol, neopentyl glycol, hexamethylene glycol, tetramethylene glycol, trimethylene glycol, and cyclohexane dimethylol may be used as part of the dihydroxy component. Among these aromatic dihydroxy compounds, bisphenol A and hydroquinone are particularly preferred. The wholly aromatic polyester can be produced by a well-known method (for example, Japanese Patent Publication No. 37-5599,
Special Publication No. 38-15247, Special Publication No. 38-2629
It can be manufactured by the method disclosed in Japanese Patent Publication No. 9, Japanese Patent Publication No. 1977-1959, and the like. Further, other polyesters such as polyethylene terephthalate or other polymers may be mixed within the range that does not impair the properties of the wholly aromatic polyester. Amide solvents The amide solvents referred to in the present invention include N,N-dimethylformamide, N,N
- A general term for solvents such as dimethylacetamide, N-methyl-2-pyrrolidone, N-acetyl-pyrrolidone, N-methyl-caprolactam, N-acetyl-caprolactam, hexamethylphosphoramide, and tetramethylurea. However, in the present invention, a solvent containing N-methyl-2-pyrrolidotone as a main component is preferably used.

Further, these amide solvents can be used alone or in combination with other solvents. Polymer solution When producing a cipal-like material by the method of the present invention, a solution of a wholly aromatic polyester dissolved in an amide solvent is introduced into a precipitant consisting of water and an amide solvent, and the solution is dissolved as fine particles. Apply a method of precipitation to form a pulpy material.

The concentration of fully aromatic polyester in a solution of fully aromatic polyester dissolved in an amide solvent varies depending on the degree of polymerization and type of fully aromatic polyester, but is generally 5 to 30% by weight.
, preferably 6 to 25% by weight, particularly preferably 7 to 23% by weight
Weight%. If the concentration of the wholly aromatic polyester in the solution is less than 5% by weight, it is undesirable because there will be a lot of leakage from the wire gauze during B1 paper making where the size of the pulp-like material obtained is extremely small. On the other hand, if the concentration of fully aromatic polyester in the solution is greater than 30% by weight, the pulp-like material obtained will have a coarse shape and few tentacles (equivalent to that shown in Figure 2). The entanglement of the pulp-like substance and the short fibers decreases, the paper-making properties deteriorate, and the mechanical properties of the obtained paper also deteriorate. The temperature of the solution during precipitation is 10 to 120°C, preferably 20 to 100°C. Additives Also, a small amount of water may be included in the solution.

Furthermore, it is not necessary to add and mix a minute amount of solid inorganic substance that does not substantially react with or dissolve in the solution, but it can improve impregnating properties, heat resistance, electrical insulation properties, and paper-making properties. This is preferable in terms of improving performance. In this case, as the solid inorganic substance, micas, asbestos, glass flakes, quartz powder, sulfur, kaolin, alumina, etc. can be used. If a solid inorganic substance is mixed, the amount is from 5 to 400% by weight, preferably from 10 to 200% by weight of the polymer. When mixing the above-mentioned solid inorganic substances into a solution, it is preferable to disperse them as uniformly as possible, and examples of equipment such as a T●K homomixer (manufactured by Tokushu Kika Kogyo),
Attritor (manufactured by Mitsui Miike Seisakusho) is effective.
Precipitant In the present invention, a precipitant in which a V1 amide solvent consisting of water and an amide solvent has a concentration of 20 to 85% by weight is used in the production of a pulp-like material.

If the concentration of the amide solvent in the precipitant is greater than 85% by weight, the pulp-like substances produced will coagulate and weld together, resulting in a decrease in the tensile strength and elongation of the sheet obtained by processing this pulp-like substance.
A decrease in dielectric breakdown voltage is expected. In addition, when the concentration of the amide solvent in the precipitant is less than 20% by weight, the shape of the pulp-like material obtained is rod-like and coarse. The entanglement between short fibers and short fibers decreases, paper-making properties deteriorate, and the mechanical properties and dielectric breakdown voltage of the obtained paper also deteriorate. The temperature of the precipitant is also
It is one of the important factors for obtaining a pulp material with good paper-making properties and a good shape.
It is 0°C.

The precipitant is preferably stirred at high speed to remove the solvent from the introduced solution and simultaneously produce a shearing or beating action.The flow rate ratio of the four precipitants is 5/l to 30
/1 is desirable, particularly preferably 8/1 to 15/1.

(Weight Ratio) Paper Making The pulp-like material produced according to the present invention can be mixed with short fibers and made into paper to form an excellent sheet.

At this time, the amount of pulp-like material in the sheet is 10 to 90% by weight.
, particularly preferably from 40 to 80% by weight. If the amount of pulp-like material is less than 10% by weight, it is not preferable because the mechanical properties and dielectric breakdown voltage of the sheet decrease.

If the amount of pulp-like material is more than 90% by weight, both the impregnating properties and the mechanical properties are poor. Paper making from the preferred duck pulp-like material and short fibers is similar to the case of paper making from conventional natural pulp. It is preferable to make paper by a wet method using a mesh type or cylinder type paper machine. At this time, a surfactant, a dispersing agent such as root juice of A. japonica, and a thickening agent may be added as necessary. The single fiber fineness of the short fibers used in the present invention is 0.5.
~10 denier, preferably l~3 denier. The fiber length of the short fibers is 1 to 20 rm, preferably 2 to 15 rm.
1, particularly preferably 3 to 10 m. Various types of short fibers can be used, and examples include the following.

1. Polypropylene fiber 2. Polyethylene fiber 3. Polytetrafluoroethylene fiber 4. Polycarbonate fiber5. Poly(2,6-diphenyl-paraphenylene oxide) fiber6. Polyamide fibers (including aromatic polyamide fibers) 7. Polyester fibers (including aromatic polyester fibers) 8. Polyacrylonitrile fiber9. Polyvinyl alcohol fiber 10. Aromatic polyamide-imide fiber 11. Polyvinyl chloride fiber 12. Polyvinylidene chloride fiber 13. Inorganic fibers such as glass fibers, slag fibers, asbestos, etc.14.
Cellulose-based regenerated fibers (viscose rayon, Kyupura, etc.) 15.1 Protein-based regenerated fibers 16. Cellulose-based semi-synthetic fibers (acetate, triacetate, acetate acetate, etc.) Among these, polypropylene fibers, polyethylene fibers, polytetrafluoroethylene fibers, polycarbonate fibers, and poly(2,6-difluoroethylene) fibers have good dielectric properties. Short fibers such as enylparaphenylene oxide fibers are particularly desirable as short fibers for producing insulating paper for high-voltage power transmission cables.

In addition, aromatic polyamide fibers, aromatic polyamideimide fibers, aromatic polyester fibers, poly(2,6-diphenylparaphenylene oxide) fibers, etc. are used when manufacturing insulating paper that requires heat resistance. It is useful for

After the sheet obtained as described above is dried, excellent performance can be imparted by heating it under pressure using a hot press, a hot roll, or the like.

The temperature at which pressure is applied varies depending on the type of short fibers and the amount of pulp-like material in the sheet, but a suitable temperature is 70 to 270°C. The pressure varies depending on the type of short fibers, the amount of pulp-like material in the sheet, etc. as well as the temperature, but it is preferably 400 Kf/Cd or less. The method of measuring the main measured values according to the present invention will be explained below. Suction strength: JISP8ll8
Elongation: Measured according to the method of JISP8l32 and expressed as %.

Dielectric breakdown voltage: Measured using AC voltage according to JISC2lll method.

Impregnability: A sample cut into a disk shape with a diameter of 10 Wt1 is floated on the surface of JISI insulating oil, and the time required for the insulating oil to permeate the entire surface is measured, and the time is divided by the thickness of the sample to calculate Sec. This measurement was carried out in a vacuum of 10 mHf. The present invention will now be described in detail with reference to Examples.

Example 1 Preparation of polymer solution 15 parts by weight of pellets of a commercially available wholly aromatic polyester (U Polymer manufactured by Unitika Co., Ltd.) were ground using a grinder and mixed with N-methyl-2 having a water content of 0.5% by weight. - The mixture was added to 85 parts by weight of pyrrolidone with stirring, and then heated to about 190°C to completely dissolve the polymer.

Then, the temperature of the solution was cooled to 30° C. to prepare a solution and scum precipitant for producing a pulp-like material. 75 parts by weight of N-methyl-2-pyrrolidone and 25 parts by weight of water were mixed as a precipitant. .

Manufacture of valve-like substances D1 consists of a combination of a stator with a bulge and a turbine blade-shaped rotor, and is equipped with a precipitant, a solution supply port, and a discharge port for pulp-like material slurry after precipitation. Add the above polymer solution 0.5K9/box 1 to the precipitator.
The n1 precipitant was fed simultaneously at a flow rate of 5K9/Min, and the pulpy material slurry was discharged from the outlet.

At this time, the temperature of the precipitant was 39°C, and the temperature of the polymer solution was 39°C.
The temperature was adjusted to 0°C. Also, the number of rotations of the rotor is 7,100
r. p. It was set as m. The resulting pulpy substance slurry is
The mixture was placed in a Nutstier type vacuum filter equipped with a 200-mesh stainless steel wire mesh, and most of the precipitant was separated as a finished liquid. Next, without discharging the pulp-like substance from the filter, 30 parts of io7-exchanged water containing the pulp-like substance (solid content) was supplied, and the mixture was washed under reduced pressure. A microscopic photograph (40x magnification) of the pulp-like material thus obtained is shown in FIG. 1.5f of pulp-like material (solid content) obtained by papermaking
When paper was made using a Tatsupi standard sheet machine from an aqueous dispersion containing polymetaphenylene isophthalamide fiber (Teijin product name: Cornex) 1.0r with a single yarn fineness of 2 denier and a fiber length of 8 Fm, water drained from the paper-making wire mesh. A sheet with good paper-making properties and good texture was obtained.

After drying this sheet, 120℃, 250Kf/Cfil
The first stage of heat pressing was carried out under the conditions of 180°C and 20°C.
The thickness was 170μ after the second stage of heat pressing under positive/Cd conditions.
got the paper.

The tensile strength of this paper is 5.9! / blowing extension: 13911, dielectric breakdown voltage: 18 KV/m1, impregnation: 650 sec/limit oxygen index: 39.

Comparative Example 1 A pulp-like material was prepared under exactly the same conditions as Example 1, except that the concentration of N-methyl-2-pyrrolidone in the precipitant was set to the concentrations shown in Tables 1 to 4 of Table 1 below. and paper was made from it.

The measurement results for these are shown in Table 1. Black 1 and 2 are examples where the concentration of N-methyl-2-pyrrolidone in the precipitant is lower than the range of the present invention.1 The shape of the pulp-like material obtained in both cases is as shown in Figure 2. , it became something gross.

Furthermore, the surface of the obtained paper was extremely uneven, and the dielectric breakdown voltage and tensile strength were also low. In addition, washings 3 and 4 contain N- in the precipitant.
When the concentration of methyl-2-pyrrolidone is too high, the pulp-like material in black 3 coagulates and welds, and the dielectric breakdown voltage of the paper is low.

When the concentration of Black 4 was higher than that of Black 3, it became hot, almost no precipitation occurred, and a pulp-like material could not be obtained.

Example 2 210.0 parts by weight of diphenyl terephthalate, 1719 parts by weight of diphenyl isophthalate, bisphenol A2
87.6 parts by weight of stannous acetate and 0.142 parts by weight of stannous acetate were charged into a reaction vessel and reacted at 280° C. under normal pressure and nitrogen atmosphere for 60 minutes, then the pressure was gradually reduced, and after 30 minutes the absolute pressure was reduced to 0.
After reaching 5% Ht or less, the solidified polymer was taken out and ground into a powder of about 20 mesh.

This thing has an absolute pressure of 0.5rf1! FtHt or less, 300
Completely aromatic polyester 4 was solid-state polymerized at ℃ for 150 minutes.
13 parts by weight were obtained. Phenol/tetrachloroethane (
Polymer 12 to 100 mt of mixed solvent (60/40 weight ratio)
The reduced viscosity measured at 35° C. after dissolving f was 1.03. A pulp-like material and paper were obtained from it in the same manner as in Example 1, except that the thus obtained wholly aromatic polyester was used as the wholly aromatic polyester.

The performance of this paper was almost the same as that of the paper obtained in Example 1, and was good. Example 3 191 parts by weight of diphenyl terephthalate, 6 parts by weight of All bisphenol, 16.5 parts by weight of hydroquinone, and 0.071 parts by weight of 1M sulfuric acid were operated in the same manner as in Example 2 to produce a wholly aromatic compound with a reduced viscosity of 10. 190 parts by weight of polyester was obtained.

Using the thus obtained wholly aromatic polyester as the wholly aromatic polyester, the temperature of the polymer solution to be subjected to precipitation was set to 10
A pulp-like substance block and paper were obtained from it in the same manner as in Example 1 except that the temperature was 0°C. The shape of the pulp-like substance was almost the same as that shown in FIG. 1, and it was difficult to distinguish between the two.

Moreover, the performance of the paper was good in all respects as follows.

Tensile strength 6.2kg/d1 elongation 115%, dielectric breakdown voltage 17Kv/Rfr! Fll impregnated 700SeC/Frl
The paper obtained by processing the pulp-like material obtained by the method of the present invention is not just a paper that can be effectively used as an electrical insulating paper by taking advantage of its excellent heat resistance and electrical insulation properties, but also an excellent paper. By applying its flame retardancy and mechanical properties, it can also be applied to Q-uses such as building materials and structural materials.

[Brief explanation of drawings]

FIG. 1 is a microscopic photograph of a pulp-like material obtained by the method of the present invention, and FIG. 2 is a microscopic photograph of a pulp-like material obtained by a method other than the method of the present invention.

Claims (1)

[Claims] 1. A solution of fully aromatic polyester dissolved in an amide solvent is introduced into a precipitant consisting of an amide solvent and water with an amide solvent concentration of 20 to 85% by weight, with stirring, to precipitate fine particles. 1. A method for producing a pulp-like substance, the method comprising: