JPS6350444B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing pulp-like materials. More specifically, from a solution of an aromatic polyamide polymer obtained from an aromatic dicarboxylic acid and an aromatic cyisocyanate and having a logarithmic viscosity ηinh of 0.5 or more, a pulp-like material with good processability and excellent physical properties after processing is produced. Relating to a method of manufacturing a substance. Conventionally, pulp-like substances obtained from aromatic polymers have excellent heat resistance and electrical insulation properties, so they have attracted attention as materials for heat-resistant insulating paper or boards, insulating tape materials, etc., and methods for producing them have been developed. There is. For example, Japanese Patent Publication No. 35-11851 describes paper pulp particles made of synthetic polymers. However, the pulp particles described in this publication not only have drawbacks during processing, such as paper-making properties, water drainage, and the degree of occurrence of thickness unevenness, but also have many unsatisfactory physical properties after processing, such as electrical insulation properties. In addition, Japanese Patent Publication No. 37-5732 discloses a method for producing synthetic polymer particles defined as fibrids, but the synthetic polymer particles obtained by this method also have poor paper-forming properties and poor formation. It is insufficient to obtain a good uniform paper, and the electrical insulation properties of the obtained paper-like material are also insufficient. Furthermore, JP-A-51-97110 discloses an improved method for obtaining pulp particles from aromatic polymers; Particles may also be produced that have an inappropriate average specific filtration resistance, and have the disadvantage that it is difficult to balance dielectric breakdown strength, tensile strength, and impregnability after paper making. As a result of various studies to eliminate these various drawbacks, the present inventors have developed an aromatic polyamide-based polymer obtained from an aromatic dicarboxylic acid and an aromatic diisocyanate and having a logarithmic viscosity ηinh of 0.5 or more in a solvent. A pulp-like material obtained by mixing a polymer solution dissolved in a polymer with a precipitant having the property of not dissolving the polymer under high shear force can be obtained by selecting conditions for forming a precipitate. , good water repellency, good paper-making properties when making paper directly or by mixing with other substances such as various short fibers, mica, kaolin, etc., good formation, little thickness unevenness, and uniformity. It is possible to obtain sheets with good balance of impregnation properties, electrical insulation properties, tensile strength, etc. after paper making, and it is also suitable for use as a filler in various plastics. It has been found that results can be obtained, and the present invention has been achieved. That is, the present invention provides an aromatic dicarboxylic acid and an aromatic diisocyanate whose logarithmic viscosity ηinh is
A solution of an aromatic polyamide polymer having a molecular weight of 0.5 or more;
This is a method for producing a pulp-like material, which is characterized by mixing with a precipitant under high shearing force. The aromatic polyamide polymer used in the method of the present invention is obtained from an aromatic polycarboxylic acid and an aromatic polyisocyanate, and has a logarithmic viscosity ηinh.
0.5 or more, preferably 0.8 or more, but in addition to this polymer, polyamide compounds, polyimide compounds, polyamide imide compounds, polyamide imidazole compounds, etc. are added to the present invention in order to adjust the physical properties of the resulting pulp. The content may be 50% by weight or less (that is, 50% by weight or more of the polymer) as long as the purpose of the polymer is not impaired. Aromatic dicarboxylic acids used in the present invention include terephthalic acid, isophthalic acid, orthophthalic acid, diphenyl ether-4,4'-dicarboxylic acid, diphenylthioether-4,4'-dicarboxylic acid, diphenylsulfone-4 , 4'-dicarboxylic acid, biphenyl-4,4'-dicarboxylic acid, thiophene-2,5-dicarboxylic acid, pyridine-2,6-
Examples include dicarboxylic acid, naphthalene 2,6-dicarboxylic acid, and isomers thereof. Further, the aromatic diisocyanates used in the present invention include phenylene-1,3-diisocyanate, toluylene-2,6-diisocyanate, tolylene-2,4-diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenyl ether-4 , 4'-diisocyanate, naphthalene-1,5-diisocyanate, diphenylsulfone-4,4'-diisocyanate, diphenylsulfide-4,4'-diisocyanate, anthraquinone-2,6-diisocyanate, diphenylketone-4, Mention may be made of 4'-diisocyanates and their isomers. The logarithmic viscosity ηinh of the above aromatic dicarboxylic acid and aromatic diisocyanate is 0.5 or more, preferably 0.8
As a method for obtaining the above aromatic polyamide, a known method or a polymerization method using a catalyst previously applied by the present applicant (Japanese Patent Application No. 56-37132) can be used, but in particular, the latter organic polycarboxylic acid A method using a monoalkali metal salt as a catalyst is preferred because it causes fewer side reactions and can easily yield a product with a high logarithmic viscosity.
Specifically, the above aromatic polyvalent carboxylic acid and aromatic polyvalent isocyanate are produced as by-products in an anhydrous organic polar solvent under a stream of inert gas or under reduced pressure.
in the presence of a catalyst such as a monoalkali metal salt of a polyhydric carboxylic acid while removing CO ₂ gas, approximately 20 to 250
This is a method in which the reaction is carried out while heating at a temperature of 1 to 20 hours. The solution of the aromatic polyamide-based polymer may be the polymerized liquid as it is after polymerization as described above, or it may be prepared by separating and purifying these polymers by a method such as precipitation separation and then redissolving them in a solvent. It can also be adjusted. The solvent for the aromatic polyamide polymer that can be used in the present invention is generally referred to as a polar protection solvent, such as N,N-dimethylacetamide, N,N-dimethylformamide,
N,N-diethylacetamide, N-methyl-pyrrolidone, hexamethylphosphotriamide, N,
N,N',N'-tetramethylurea, dimethylsulfoxide sulfolane, diphenylsulfoxide,
Examples include benzophenone and inorganic solvents such as sulfuric acid, chlorosulfuric acid, polyphosphoric acid, and chlorosulfuric acid. Aromatic polyamide solutions contain 2 to 40% by weight of aromatic polyamide polymer in these solvents, but if the concentration is too low, only fine particles will be produced.
Furthermore, if the concentration is too high, flaky substances unsuitable for pulping, such as paper making, are likely to be produced, so it is preferable to contain the polymer in an amount of 5 to 30% by weight. Furthermore, depending on the properties of the aromatic polyamide solution, if a solution containing only the above-mentioned polar aprotective solvent or inorganic solvent is inconvenient in handling, water, methanol, ethanol, acetone, dioxane, organic By adding amines such as ethylenediamine, diethylenetriamine, ethanolamine, and inorganic compounds such as lithium chloride, cerium chloride, calcium chloride, etc., the liquid viscosity can be adjusted.
It is preferable to adjust solubility and the like. As the precipitant used in the present invention, a wide range of substances can be used as long as it does not dissolve the aromatic polyamide used, but it is preferable that it is miscible with the polymer solution, such as water, glycerin, Examples include ethylene glycol, mixtures of water and organic solvents, and mixtures of water and inorganic substances.
An aqueous solution is suitable for obtaining a good pulp-like material, and it is particularly preferable to use a solution containing 5 to 90% by weight of water. In the method of the present invention, when producing a pulp-like material from a solution of an aromatic polyamide polymer and a precipitant, it is important to apply a high shearing force to the interface between the two solutions. The force, injection speed, etc. vary greatly depending on the properties of the solution and precipitant, but at least where the two solutions come into contact, a turbulent state is preferable, and the Reynolds number needs to be about 3000 or more. This kind of high shear force is
It can be obtained using a precipitation device equipped with stirring blades that can rotate at high speed, a device that performs high-speed pump stirring, and a spray nozzle that can spray at high speed. Any material may be used as long as it can apply shearing or beating force to the material and give the precipitate an appropriate shape and size. The properties of the polymer solution, the precipitant, and the shearing force applied to both yarns are important as conditions for producing pulp-like materials, but the temperature at which the pulp powder is precipitated also affects the solubility of the polymer in these systems, the solvent It is important to adjust the extraction rate, etc., and unless these are properly controlled, a desirable pulp-like material cannot be obtained.
The optimum temperature varies depending on the type of polymer, the nature of the solvent, the nature of the precipitant, the applied shear force, etc., but in order to produce a pulp-like material with economically favorable properties, mixing the precipitant with the polymer solution is necessary. It is generally preferred that the temperature of the liquid be slightly higher than room temperature, that is, in the range of 35 to 95°C. At temperatures lower than 35°C, the rate at which the solvent in the polymer solution is extracted is slow and the solid remains suspended for a long time with a large amount of residual solvent, which usually requires a large amount of precipitant, which is not economical. . On the other hand, at temperatures above 95°C, depending on the selection of solvent and precipitant, concentration changes generally occur due to evaporation, making it difficult to control liquid properties. In order to avoid this, a pressurizing device is required, and even if this type of device is used to adjust the liquid properties, the solvent extraction rate from the polymer solution is too fast, so only the surface of the precipitated solid solidifies. On the contrary, complete extraction of the solvent is likely to be hindered. In the method of the present invention, it is important to mainly use aromatic polyamides obtained from aromatic dicarboxylic acids and aromatic diisocyanates, and although the exact reason is unknown, the polymer obtained by this method does not contain end groups. It is thought that this is due to the solubility in various solvents, which is thought to be largely influenced by the properties of the polar group, and the degree of polymerization distribution caused by raw materials and manufacturing methods, which are suitable for producing pulp-like substances, which is the objective of the present invention. It will be done. Furthermore, as the aromatic polyamide used in the present invention, in order to obtain the maximum effect of the present invention, as mentioned above, it is most preferable to use a monoalkali metal salt of a polyhydric carboxylic acid as a catalyst. It is an aromatic polyamide obtained by reacting a group dicarboxylic acid with an aromatic diisocyanate, and its degree of polymerization expressed in terms of logarithmic viscosity ηinh is preferably 0.5 or more, and particularly preferably 0.8 or more. If the logarithmic viscosity ηinh is less than 0.5, the resulting pulp-like material will be finer than necessary, and the average specific filtration resistance will tend to increase. Even if a pulp with physical properties similar to those of the pulp obtained by coalescence is obtained, the tensile strength of paper-like products made from it is not sufficient. The pulp water material produced under the conditions detailed above mainly consists of aromatic polyamide obtained from aromatic dicarboxylic acid and aromatic diisocyanate, has good uniformity of individual pulp materials, and contains unnecessary fine particles and There are almost no large particles, and pulp-like materials with desired properties can be obtained by selecting conditions, and after obtaining the pulp-like materials, separation from solvents, precipitants, etc., and washing can be performed efficiently. , removal of residual solvent in the pulp-like material is also easy. The pulp-like material obtained by the method of the present invention can be used for insulating paper by directly or by mixing various organic or inorganic short fibers, inorganic fillers such as mica, kaolin, etc. into paper. In addition, when the pulp-like material produced by the method of the present invention is used, it is possible not only to obtain paper with good paper-making properties such as drainage during processing, for example, during paper-making, and with good texture and uniformity, but also to improve dielectric breakdown strength and oil impregnation after paper-making. A paper-like material with excellent mechanical properties such as hardness and tensile strength can be obtained. Further, the pulp according to the present invention is easily homogenized when mixed with various short fibers and fillers, and is convenient for use in combination with these substances. Further, the pulp-like material produced by the method of the present invention can be used alone or in combination with other materials as a filler or reinforcing material for various plastic bags. The details of the present invention will be explained below in Examples, and the main measuring methods and abbreviations used in the Examples are as follows. Logarithmic viscosity: ηinh=ln(t/to)/C C: Polymer concentration in solution (g/100ml) t: Solution flow time (seconds) to: Solvent flow time N-methyl 2-pyrrolidone or 95% sulfuric acid Inside,
Measurements were made at 30°C at a concentration of 0.5g/100ml. Average specific filtration resistance 38mm inner diameter with plug and 200 mesh wire mesh at the bottom;
Put pulp suspension with a concentration of 0.5% by weight into a 1400 mm long glass tube up to 1200 mm from the wire mesh, and remove the stopper at the bottom to drain the water. The decrease in water level was measured over time, and the average specific filtration resistance was determined using the following formula. Average specific filtration resistance = ρgb/ηCHo: Water density (g/cm ³ ) g: Gravitational acceleration 980 (cm/sec ² ) b: Drainage resistance (sec) η: Water viscosity (g/cm・sec) c: Pulp concentration (g/ml) Ho: Initial water level 120 (cm) Dielectric breakdown strength Measured with alternating current according to the method of JISC 2111. Impregnation property Floating a sample piece with a diameter of 2 cm on JIS No. 1 insulating oil,
The time required for oil to penetrate the surface of the paper was measured. Abbreviation IPA: Isophthalic acid TPA: Terephthalic acid IPA-cl: Isophthalic acid chloride TPA-cl: Terephthalic acid chloride IPA-Na: Isophthalic acid monosodium salt TPA-Na: Terephthalic acid monosodium salt TDI: Toluylene diisocyanate (not specified) (2,4-12,6-isomer = 80/20 weight ratio) MDI: diphenylmethane-4,4'-diisocyanate NMP: N-methyl-2-pyrrolidone DMA: dimethylacetamide mA: metaphenylenediamine PA: paraffin Enylenediamine Parts, percentages, and ratios below are based on weight unless otherwise specified. Example 1 (A) Production of polymer A solution in which 42 parts of IPA and 2.8 parts of IPA-Na were dissolved in 520 parts of NMP was charged into a reactor equipped with a stirrer, a thermometer, a raw material supply port, and an inert gas inlet. Add 49 parts of TDI while heating to 80°C in a bath. After stirring and mixing thoroughly in this state, the temperature of the oil bath is raised and the internal temperature is maintained at 140°C for 5 hours.
After almost no carbon dioxide gas is generated, the internal temperature is further raised to 170°C and kept for 1 hour. After the reaction is complete, about 180 parts of NMP is added and the mixture is cooled to room temperature. The logarithmic viscosity and concentration of the obtained polymer solution were measured by sampling, and the results showed that the polymer ηinh was 1.93 and the polymer concentration was 11%. (B) Pulp-like material production Aqueous solution 3 containing 40% calcium chloride
Heat to 80℃ and use a high-speed stirring mixer (Nippon Seiki).
Using a two-fluid spray nozzle (SSCO No. 1665, No. 73335), the polymer solution produced in (A) was sprayed at a speed of 50 ml/min while stirring at a rotational speed of 5000 rpm. ) and the above coagulating liquid at a total rate of 650 ml/min. The produced pulp-like material was separated by vacuum filtration and then thoroughly washed with a large amount of water. The results of measuring the amount of the obtained pulp-like material that passed through a 150-mesh wire mesh and the average specific filtration resistance were as follows. Passage through 150 mesh wire mesh 53.5% Average filtration resistance 89×10 ⁷ cm/g (C) Production of sheet-like material The pulp-like material obtained in (B) was cut into a length of 3 mm with a single fiber fineness of 2 denier. Aromatic polyamide fibers obtained from mA and IPA-cl were summed in a 1:1 ratio.
Paper was made from an aqueous dispersion containing 10 g/g of paper using a Tatsupi standard sheet machine. Paper-making properties were extremely good, water drainage was sufficient, and a uniform sheet with no unevenness was obtained. This sheet was hot pressed at 270° C. and 100 kg/cm ² to produce a paper-like product with a thickness of about 120 μm.
The results of various physical property measurements of this paper-like material were as follows. Electrical breakdown strength 53KV/mm Impregnability 2200seo/mm Tensile strength 2.5Kg/mm ² Elongation 2.0% Examples 2 to 6 The polymer solution obtained in Example 1 (A) was prepared using the same method as (B). A pulp-like material was produced while varying the rotation speed of the high-speed stirring mixer, separated and washed in the same manner, and its physical properties were measured. The results are shown in Table 1.

[Table] Examples 7 to 12 Using the method of Example 1 (A), a pulp-like material was produced by the method of Example (B) using a polymer obtained by variously changing the raw material isocyanate and carboxylic acid, Their physical properties were measured. The results are shown in Table 2.

[Table] Examples 13 to 18 Regarding the polymer produced by the method of Example 12, the polymer solution was gradually added to a large amount of methanol to precipitate the polymer as a solid, and after thorough washing with methanol and drying, it was mixed at various concentrations. Redissolve in NMP,
Polymer solutions with different concentrations were prepared. A pulp-like material was obtained from this polymer solution by the method of Example 1-(B), and a paper-like material was further produced by the method of Example 1-(C). Table 3 shows the results of measuring the physical properties of the obtained pulp-like material and paper-like material.

[Table] Examples 19 to 25 Tests were conducted using the method of Example 16 with various changes in the conditions for producing pulp-like substances, such as the type of precipitant, concentration, and mixing temperature, and the properties of the resulting pulp were measured. , observed. The results are shown in Table 4.

[Table] Example 26 (A) Production of polymer A solution in which 19.5 parts of TPA was dissolved in 200 parts of NMP,
The mixture is placed in a reactor equipped with a stirrer, a thermometer, a raw material supply port, and an inert gas inlet, and 21.2 parts of TDI is added thereto and thoroughly stirred and mixed. Thereafter, the internal temperature was raised to 140°C and reacted for 4 hours, and after almost no gas was generated, the internal temperature was further raised to 170°C and maintained for 1 hour. After the reaction, dilute by adding about 100 parts of NMP, and cool to room temperature. The viscosity and concentration were measured by sampling the obtained polymer solution. As a result, the logarithmic viscosity ηinh of the polymer was 0.59, and the polymer concentration was 11%. (B) Production of pulp-like substances and paper-like substances The polymer solution obtained in (A) was used in Example 1 (B) and (C).
A pulp-like material and a paper-like material were produced using the method of . The physical properties of the pulp-like material and the paper-like material obtained were as follows. Pulp-like substance Passed through 150-mesh wire mesh 67.2% Average specific filtration resistance 98×10 ⁷ cm/g Physical properties of paper-like material Electrical breakdown strength 51 KV/mm Impregnation 3600 sec/mm Tensile strength 1.7 Kg/mm ² Elongation 1.3% Comparative Example 1 (A) Production of polymer 11 g of lithium carbonate was added to a solution of 1.7 g of mA dissolved in 400 g of NMP, and after cooling in a water bath, IPA-
Add 31.9 g of Cl powder and stir thoroughly for about 30 minutes while cooling. The viscosity and concentration measurement results obtained by sampling a portion of the obtained polymer solution indicate the logarithmic viscosity ηinh of the polymer.
The polymer concentration was 2.10 and the polymer concentration was 8.5%. (B) Production of pulp-like substances and paper-like substances The polymer solution obtained in (A) was used in Example 1 (B) and (C).
A pulp-like material and a paper-like material were produced by the method described in the following. The physical properties of the pulp-like material and the paper-like material obtained were as follows. Pulp material Passing through 150 mesh wire mesh 47.1% Average specific filtration resistance 59×10 ⁷ cm/g Paper material Electrical breakdown strength 37 KV/mm Impregnation 2700 sec/mm Tensile strength 0.9 Kg/mm ² Elongation 3.2% The sheet-like material produced by this method had a lot of uneven thickness, and it seemed difficult to use it industrially. In addition, when the conditions for hot pressing the obtained sheet-like material were changed from 270℃ and 100Kg/cm ² to 310℃ and 200Kg/cm ² , the physical properties of the obtained paper-like material were as follows, and the impregnation property was remarkable. It decreased significantly. Electrical breakdown strength 57KV/mm Impregnation 7400sec/mm Tensile strength 2.6Kg/mm ² Elongation 2.3% Comparative example 2 (A) Production of polymer Same procedure except that the amount of catalyst IPA-Na during polymerization was 0.28 parts In the same way as Example 1, add 42 parts of IPA and
49 parts of TDI was polymerized in 520 parts of NMP. After diluting and cooling the polymerization solution, sampling analysis revealed that the logarithmic viscosity ηinh of the polymer was 0.44 and the polymer concentration was 11%. (B) Production of pulp-like substances and paper-like substances The polymer solution obtained in (A) was used in Example 1 (B) and (C).
A pulp-like material and a paper-like material were produced using the method of . The physical properties of the pulp-like material and paper-like material obtained were as follows. Pulp material Passing through 150 mesh wire mesh 71.6% Average specific filtration resistance 115×10 ⁷ cm/g Paper material Electrical breakdown strength 48 KV/mm Impregnation 6900 sec/mm Tensile strength 0.3 Kg/mm ² Elongation 2.2% Comparative example 3 (A) Production of polymer Toluenediamine (2,4
A polyamide was obtained in the same manner as in Comparative Example 1 except that 19.2 g of isomer ratio of isomer/2,6 isomer = 80/20) was used. The logarithmic viscosity ηinh of the polymer was 1.90, and the polymer concentration was 11.0% by weight. (B) Production of pulp-like material and paper-like material The polymer solution obtained in (A) was prepared in Example 1 (B) and
A pulp-like substance and a paper-like substance were produced by the method (C). The physical properties of the pulp-like material and paper-like material obtained were as follows. Pulp-like material 150 mesh 42% Average specific filtration resistance 40×10 ⁷ cm/g Paper-like material Electrical breakdown strength 25 KV/mm Impregnation 2100 sec/mm Tensile strength 0.8 Kg/mm ² Elongation 2.7% Paper of Example 1 The physical properties (electrical breakdown strength, impregnability, tensile strength, and elongation) of the paper-like material of this comparative example were all inferior to those of the paper-like material, and the paper texture was poor and uneven.

Claims (1)

[Claims] 1. A solution of an aromatic polyamide polymer obtained from an aromatic dicarboxylic acid and an aromatic diisocyanate and having a logarithmic viscosity ηinh of 0.5 or more is mixed with a precipitant under high shearing force. A method for producing a pulp-like substance characterized by: 2 The solution contains 5 aromatic polyamide polymers.
30% by weight of the manufacturing method according to claim 1. 3. The manufacturing method according to claim 1, wherein the precipitant is a liquid containing 50 to 90% by weight of water. 4 The temperature of the mixture of precipitant and polymer solution is
The manufacturing method according to claim 1, wherein the temperature is in the range of 35 to 95°C.