JPS5825767B2 - Barpuri Yuushi Oyobi Sono Seizouhouhou - Google Patents

Description

[Detailed description of the invention] TECHNICAL FIELD The present invention relates to pulp particles and a method for producing the same.

More specifically, it is a pulp particle that can provide a sheet with excellent heat resistance, electrical insulation, and improved mechanical properties, and is a pulp particle obtained by heating a carboxylic acid mixture of a specific composition and a specific diisocyanate. It is a pulp particle whose main resin component is aromatic polyamideimide, and other 1
The first is an industrially advantageous method for producing pulp particles having good paper-making properties.

Conventionally, natural pulp is the most well-known pulp particle used in paper.

Paper made from natural pulp is often used as electrical insulating paper, but it has the major drawback of lacking heat resistance. That's far from it.

Recently, pulp particles obtained from synthetic polymers have attracted attention as materials for electrically insulating paper because of their excellent heat resistance and electrical insulation properties.

For example, in Japanese Patent Publication No. 48-11816, LiC1°LiBr and C
A method is described for producing a pulp-like article for electrically insulating paper by adding a compound selected from aCl2 to an aromatic polyamide in an amount of 1 to 20% by weight, and then dispersing the solution in a precipitant.

Although the paper made from the pulp-like material obtained by this method has excellent heat resistance, its dielectric breakdown strength is still insufficient, and its mechanical properties and dimensional stability when absorbing moisture are at a satisfactory level. It can not be said.

Furthermore, since inorganic salts such as LiC1y Li13r and CaCl2 are added to the polymer solution, the cleaning process to remove them from the pulp-like material is extremely troublesome, and these inorganic salts require equipment. There is a high possibility of corrosion, and in industrial manufacturing facilities, it is necessary to pay attention to the material, and the equipment cost increases, so it is not necessarily a preferable method.

In addition, Japanese Patent Publication No. 47-14761 describes pulp-like particles made of asbestos fibers and aromatic polyamide, but paper made from these pulp-like particles also has poor mechanical properties and electrical insulation properties. It is therefore insufficient in its performance as an electrically insulating paper which requires a high degree of reliability in its performance.

Furthermore, Japanese Patent Publication No. 43-20421 describes a high-temperature-resistant sheet-like structure suitable for electrical insulation, which is made of a tangled mixture of granular mica and substantially unmelted aromatic polyamideimide. .

However, the sheet-like structure described herein also has insufficient mechanical properties and impregnability, especially as an electrical insulating material for electrical equipment that should be made smaller and lighter.

Furthermore, when producing such a sheet-like structure, the mica and fibrids separate, making the papermaking process extremely difficult.

Furthermore, such a sheet-like structure has the disadvantage that the mica easily peels off due to friction.

We aim to overcome these shortcomings, namely: ■Improvement in electrical insulation ■Improvement in heat resistance and flame resistance ■Improvement in impregnation ■Improvement in mechanical properties ■Dimensional stability when absorbing moisture ■Improvement in paper-making properties■ As a material that can improve the peeling resistance of mica, first, mica particles of 50 to 90
proposed a pulp particle consisting of i% by weight and 50 to 10% by weight of an aromatic polymer, in which mica particles are covered and connected with an aromatic polymer (Japanese Patent Application Laid-open No. 4898107). The resulting sheet has excellent heat resistance, impregnation properties, peeling resistance of mica particles, electrical insulation properties, etc. When the aromatic polymer is a specific aromatic polyamideimide, Although a sheet with better dimensional stability upon moisture absorption than aromatic polyamide was obtained, the mechanical properties were still insufficient.

After that, the present inventor further investigated the aromatic polyamideimide, especially for the purpose of improving its mechanical properties, without impairing the characteristics of the aromatic polyamideimide. A solution of N-methyl-2-pyroIJ ton of a specific aromatic polyamide-imide having more amide bonds than imide bonds, which is obtained by heating a specific proportion of a carboxylic acid mixture and a specific diisocyanate, is heated under specific conditions. Pulp particles with good paper-making properties can be obtained by introducing them into a satisfactory precipitant and precipitating them as fine particles.The sheets obtained by processing these pulp particles have properties such as heat resistance, impregnation properties, flame resistance, Not only does it have excellent insulation properties and dimensional stability, but it also has improved mechanical properties, and there is no need to worry about corrosion of manufacturing equipment, making selection of equipment materials and maintenance work more advantageous. The present invention was completed by discovering that the amount of water required for washing particles can also be reduced.

That is, the present invention is composed of 0) 4,4'-bis(trimellidoimide)diphenylmethane and/or 4,4/-bis(trimellidoimide)diphenylnitertoisophthalic acid and/or terephthalic acid, whose composition is the first
A carboxylic acid mixture within the shaded range in the figure and 4.
Pulp particles whose main resin component is aromatic polyamideimide obtained by subjecting 41-diphenylmethane diisocyanate and/or 4,4'-diphenyl ether diisocyanate to a thermal reaction.

(tI) is composed of 4,41-bis(trimellidoimide)diphenylmethane and/or 4,4'-bis(trinolitimide)diphenyl ether and isophthalic acid and/or terephthalic acid, and its composition is shown by diagonal lines in Figure 1. N-methyl-2-pyronodone bath solution of aromatic polyamide obtained by thermally reacting a carboxylic acid mixture within the range with 4,4/-diphenylmethane diisocyanate and/or 4,4/-diphenyl ether diisocyanate, N-methyl- so that the coagulation value is 25-40.
Water with adjusted concentration of 2-pyrrolidone and N-methyl-2-
This is a method for producing pulp particles, which is characterized in that the pulp particles are introduced into a precipitant consisting of pyrrolidone under stirring and precipitated as fine particles.

The imidodicarboxylic acid used in the present invention is 4.4'
- bis(trimellidoimide) diphenylmethane and/or 4,41-bis(trimellidoimide) diphenyl ether (hereinafter referred to as imidodicarboxylic acid),
For example, Japanese Patent Publication No. 3821500, Japanese Patent Publication No. 41-19
It can be produced by the method described in Japanese Patent No. 302 and the like.

In particular, 4.4/-bis(trimellidoimide)diphenylmethane is used in the embodiments of the invention.

Further, the diisocyanate used in the present invention is 4,4' diphenylmethane diisocyanate and/or 4,4'
- diphenyl ether diisocyanate, 4.4
'-diphenylmethane isocyanate is preferably used.

Moreover, a part of the imidodicarboxylic acid or diisocyanate can be replaced with another imidodicarboxylic acid or another diisocyanate other than those mentioned above, within a range that does not change the characteristics of the polyamide-imide used in the present invention.

In order to obtain the aromatic polyamideimide used in the present invention, it is also possible to react a carboxylic acid mixture consisting of imidodicarboxylic acid, isophthalic acid and/or terephthalic acid, and a diisocyanate in a molten state.
The imidodicarboxylic acid and the aromatic polyamideimide obtained have a high melting point, and the reaction may not proceed in a homogeneous state, so it is preferable to carry out the reaction in the presence of an inert organic polar solvent.

The reaction solvent is used to dissolve at least one, preferably both, of the carboxylic acid mixture consisting of imidodicarboxylic acid, isophthalic acid and/or terephthalic acid, and diisocyanate, and also to dissolve the low molecular weight polymer produced during the reaction to a sufficiently high molecular weight. Until an aromatic polyamide-imide is obtained, it is required that the reaction solvent at least swells and preferably dissolves to the extent that the activity is not lost. Examples of suitable reaction solvents include N-methyl-2-pyrrolidone, N-methyl-2-pyrrolidone, N, N'
-dimethylacetamide, dimethylformamide, hexamethyl-phosphoramide, etc., and N-methyl-2-pyrrolidone (hereinafter abbreviated as TNMP) is particularly preferred.

When polycondensation is carried out in the presence of an organic solvent, it is preferable to dissolve imidodicarboxylic acid and isophthalic acid and/or terephthalic acid in the reaction solvent, and then add diisocyanate.

The carboxylic acid mixture and the diisocyanate are preferably reacted in an equimolar to an excess of about 10 molar amounts of the diisocyanate.

The reaction humidity is preferably in the range of 100°C to 180°C,
Carbon dioxide gas generated during the reaction must be sufficiently removed.

After the completion of the reaction, the obtained polymer can be separated by reprecipitation by pouring the reaction mixture into a non-solvent, but if the reaction solution is obtained uniformly at the end of the reaction, it can be used as it is. Alternatively, it can be used as a stock solution for pulp production by diluting it with a suitable solvent or adding additives.

The composition of the carboxylic acid mixture used in the present invention is
When the range is outside the shaded range in the figure, the low-weight polymer in the middle of the reaction will not dissolve in the reaction solvent, solid matter will precipitate, and the reaction will not proceed uniformly, making it impossible to obtain a polymer with a sufficiently high molecular weight. becomes difficult.

For example, the area where terephthalic acid exceeds 30 molar width, such as point A in Figure 1, which is 45 moles of imidodicarboxylic acid, 5 moles of isophthalic acid, and 50 moles of terephthalic acid, and point B1, which is 10 moles of imidodicarboxylic acid, and 8 moles of isophthalic acid.
Areas where isophthalic acid exceeds 75 moles, such as 0 mo/1/t, 10 moles φ of terephthalic acid, and furthermore, areas where isophthalic acid exceeds 75 moles, such as point C, i.e. 5 moles of imidodicarboxylic acid, 70 moles of isophthalic acid, 25 moles of terephthalic acid, etc., imidodicarboxylic acid. acid is 10
In a range smaller than the molar width, it is difficult to obtain a polymer with a sufficiently high molecular weight, and pulp particles produced using aromatic polyamideimide obtained from a carboxylic acid mixture and diincyanate in this range are When processed into paper, the mechanical properties are unsatisfactory.

Furthermore, undissolved substances are present, which often lowers the electrical breakdown strength.

Therefore, only when the composition of the carboxylic acid mixture is within the shaded range in FIG. 1, pulp particles capable of providing paper with excellent mechanical properties can be obtained.

In producing the pulp particles of the present invention, a method is applied in which an NMP solution of a polymer is introduced into a precipitant consisting of water and NMP, and fine particles are precipitated to form pulp particles.

The concentration of the polymer in the polymer solution varies depending on the type of polymer, the degree of polymerization, etc., but it is preferably about 2 to 15% by weight.

Further, the solution may contain 1 to 10 weights of water, preferably 3 to 9 weights of water.

In addition, adding and mixing minute solid inorganic substances that do not substantially react with or dissolve in the solution can improve impregnation,
This is preferable in order to further improve heat resistance and electrical insulation.

In this case, the solid inorganic substance is preferably mica, which has excellent electrical insulation and heat resistance, and furthermore, asbestos, glass flakes, quartz powder, Merck, kaolin, alumina, calcium sulfate, etc. can be used.

When a solid inorganic substance is mixed, 10 to 9 of the above polymer
00% by weight, preferably 100 to 400% by weight.

When mixing the solid inorganic substance described above into a solution, it is preferable to disperse it as uniformly as possible, and effective devices include, for example, Atliterator (manufactured by Mitsui Miike Seisakusho), T, Homomixer (manufactured by Tokushu Kika Kogyo), etc. be.

Next, the precipitant used in the present invention is composed of water and NMP,
The concentration of NMP must be adjusted depending on the type of polymer, etc. so that the coagulation value measured by the method described below is 25 to 40.

If the coagulation value is greater than 40, the produced pulp particles will coagulate and weld, leading to a decrease in the dielectric breakdown voltage of the sheet obtained by processing the pulp particles.

On the other hand, if it is smaller than 25, especially if it is larger than 20, the filterability of the resulting pulp particles will be poor, and water will not drain well from the wire gauze during paper making, making it difficult to obtain a uniform sheet with good texture.

Furthermore, if it is less than 20, the shape of the obtained pulp particles becomes rod-like and large, and the dielectric breakdown voltage of the sheet deteriorates.

The NMP concentration in the precipitant that gives a coagulation value of 25 to 40 varies depending on the type of polymer, especially the amount of imidodicarboxylic acid in the carboxylic acid mixture.
The concentration must be high.

The temperature of the precipitant is also one of the important factors for obtaining pulp particles with good paper-making properties, and is preferably 10 to 50°C, preferably 20 to 50°C.
The temperature is 45°C.

The precipitant is operated so as to remove the solvent from the introduced solution by stirring at high speed and at the same time to produce a shearing action or a beating action.

The pulp particles of the present invention can be made into an excellent sheet by mixing them with short fibers and making paper.

At this time, the amount of pulp particles in the sheet is preferably 30 to 95% by weight.

Particularly preferably, the amount is 40 to 90% by weight.

If the amount of pulp particles is less than 30% by weight, the dielectric breakdown voltage and mechanical properties of the sheet will decrease, which is not preferable.

If the amount of pulp particles is more than 95% by weight, the impregnating property will be poor.

Paper made from pulp particles and short fibers is preferably made by a wet process using a fourdrinier or cylinder type paper making machine, similar to the conventional paper making from natural pulp.

The short fibers used at this time may be any heat-resistant fibers.

The single fiber fineness of short fibers is 0.5 to 10 deniers, especially 1.0 to 10.
3.0 denier is preferred.

Further, the length of the short fibers varies depending on the single fiber fineness of the short fibers, but is preferably 1 to 10 mm, preferably 3 to 8 myths.

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

The temperature at which pressure is applied varies depending on the type of polymer, the type of short fibers, etc., but 1100C to 350C is appropriate.

Like the temperature, the pressure varies depending on the type of polymer, etc.
0 to 9/CrrI2 or less is desirable.

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

Logarithmic viscosity ηinh :N-methyl-2-pyrrolid Concentration 0.5,97100 in The measurement was carried out at 30°C.

; According to JISC2111 method Measured using AC voltage.

; According to JISP8113 method 9/an2 to be implemented accordingly. I did.

; According to JISP8132 method It was measured and expressed as excellent.

; According to JISP8127 method It was measured at RH65.

; Contains 2 weight φ of polymer 20 grams of NMP solution, Drop the precipitant while stirring The point at which permanent precipitation occurs Amount of precipitant dropped (a graph) ) and then use the following formula to calculate I asked for it.

breakdown voltage tensile strength Shin Every time Sucking dampness sex stiffness solid value The present invention will be explained in detail with reference to Examples below.

Example 1 Preparation of polymer solution 30 moles of 4,4'-bis(trimellidoimide)diphenylmethane, 50 moles of isophthalic acid, 20 moles of terephthalic acid
N-methyl-2-
The reaction was carried out in pyrrolidone with a 4.5 molar excess of diincyanate to obtain a solution containing 25% by weight of polyamideimide (logarithmic viscosity in N-methyl-2-pyrrolidone, 0.70).

(Solution A) Separately, 190 parts by weight of ion-exchanged water was added to 2350 parts by weight of N-methy#-2-pyrrolidone, and the particle size measured by the Andreasen pipette method was 400 to 1000.
Add 418 parts by weight of mica powder equivalent to mesh, then T
, then stirred with a homomixer for 40 minutes to add N-methyl 2
- A mixed solution consisting of pyrrolidone, water and mica was obtained.

(Mixed liquid B) Next, add 90 parts of solution A to 2985 parts by weight of mixed liquid B.
0 parts by weight was added and stirred until homogeneous to obtain a solution for precipitation.

(Solution C) Preparation of precipitant A precipitant was prepared by mixing 56 parts by weight of N-methyl-2-pyrrolidone and 44 parts by weight of water.

The coagulation value was measured and found to be 34.

Production of Pulp Particles The solution is transferred to a conduit agitation type continuous precipitator, which consists of a combination of a stator with baffles and a turbine blade-type rotor, and is equipped with a supply port for the precipitated solution simultaneously and a discharge port for the pulp particle slurry after precipitation. C0.5kg/m i, n% precipitant 5k! The pulp particles were simultaneously fed at a flow rate of 9/min and the pulp particle slurry was taken out from the outlet.

At this time, the temperature of the precipitant was adjusted to 33°C, and the temperature of solution C was adjusted to 20°C.

Further, the rotation speed of the rotor was set to 7100 r, pm.

The resulting pulp particle slurry was placed in a centrifuge, and most of the precipitant was removed as a filtrate.

Next, ion-exchanged water was supplied for thorough cleaning.

Papermaking Pulp particles thus obtained 2.169 (solid content) and 7
Paper was made from an aqueous dispersion containing aromatic polyamide fibers (manufactured by Kijinsha, Konex) 0.549 cut into piles using a Tarapy standard sheet machine, and a sheet with good papermaking properties and good texture was obtained. .

This sheet was hot pressed at 270° C. and 200 kg/crf12 to obtain paper with a thickness of 110 μm.

The tensile strength of this paper is 5.4 kg/mr+! 2. The elongation was 4.0, which was good.

In addition, the dielectric breakdown strength was 29 mm/am. Furthermore, this paper was immersed in silicone oil and heated to 100 °C at 240 °C.
After being left for 0 hours, the tensile elongation hardly changed and the heat resistance was good.

Comparative Example 1 An example in which the carboxylic acid mixture is different from that for producing the pulp particles of the present invention is shown for comparison.

Example 1 was carried out in the same manner as in Example 1, except that a carboxylic acid mixture consisting of 33 moles φ of 4.4/-bis(trimellidoimide)diphenylmethane and 67 moles of trimellidic anhydride was used, and a polyamideimide with a logarithmic viscosity of 0.80 was obtained. .

Then, N-methyl-2-pyrrolidone 70 as a precipitant
Pulp particles were produced and paper was made in exactly the same manner as in Example 1, except that a mixed solution (coagulation value: 34) consisting of 30 parts by weight and 30 parts by weight of water was used.

Although the dielectric breakdown strength of the thus obtained paper was good,
Tensile strength and elongation are 3. It was bad at 2.1.3 skg/m, which was not at a satisfactory level.

Examples 2 to 9 Pulp particles were obtained in the same manner as in Example 1, with various proportions of the carboxylic acid mixture, ie, 4,4'-bis(trimellidoimido)diphenylmethane, isophthalic acid, and terephthalic acid.

However, the NMP concentration in the precipitant was varied depending on each polymer so that the coagulation value was 34.

Paper was obtained from the obtained pulp particles in the same manner as in Example 1.

During paper making, water drained well from the wire mesh, and the paper was well-formed and uniform.

Table 1 shows the relationship between the composition of the carboxylic acid mixture and the tensile strength and elongation of the obtained paper.

In either case, the dielectric breakdown strength is good at 27 to 30 KV/mm, and the mechanical properties are also good as shown in Table 1.

Comparative Example 2 An example in which the composition of the carboxylic acid mixture deviates from the shaded range in FIG. 1 is shown below as a comparative example.

4,4/-bis(trimellidoimide)diphenyl 1
4. A carboxylic acid mixture consisting of 60 moles of terephthalic acid and 40 moles of terephthalic acid; When 4'-diphenylmethane diisocyanate was reacted with diisocypho in N-methyl-2-pyrrolidone in a 15 molar excess, many fine undissolved substances were found floating.

After removing undissolved matter using a filter press, the logarithmic viscosity was measured and found to be 035.

Pulp particles were produced in the same manner as in Example 1 except that the concentration of N-methyl-2-pyrrolidone in the precipitant was 63% by weight (coagulation value 34), but the obtained pulp particles were very large in size. It was small and there was a lot of leakage from the cloth washed by the centrifuge, which was not desirable.

Next, paper was obtained in the same manner as in Example 1, but the strength and elongation of this paper were 2.9 kg/mm'', Q, and 9 da, respectively, which were poor.

Furthermore, the dielectric breakdown strength was low at 21 KV/m, probably due to undissolved substances that could not be removed by the filter press.

Comparative Example 3 100 moles of 4.4 novis(trimellidoimide)diphenylmethane and 4,4/-diphenylmethane diisocyanate were reacted in an excess of 14 moles of diisocypho in N-methyl-2-pyrrolidone to form polyamideimide (logarithmic viscosity [Q , 73) was obtained in an amount of 25% by weight.

Next, pulp particles were obtained in the same manner as in Example 1 except that the amount of N-methyl-2-pyrrolidone in the precipitant was adjusted to 70% (coagulation value: 34).

Using these pulp particles, a paper having a thickness of 115 μm was obtained in the same manner as in Example 1.

Paper-making properties were good, but Kono paper (D tensile strength: 3.3
kg/fi7K'' and elongation was 1.5%, which were not at a satisfactory level.

Example 10 A carboxylic acid mixture consisting of 4,4'-bis(trimellidoimide)diphenylmetafluoride: 0 mol, east isophthalic acid, 15 moles, terephthalic acid, 15 moles, and 4,4'-diphenylmethane diisocyanate, N-methyl -2-
After reacting in pyrrolidone with a 3.5 molar excess of diisocyanate, it was further diluted by adding N-methyl-2-pyrrolidone, and polyamideimide (logarithmic viscosity 0.72) was
．． A 0 weight polyfunctional solution was obtained.

(Solution A) On the other hand, a mixed solution consisting of 762% by weight of N-methyl-2-pyrrolid and 38% by weight of water was prepared as a precipitant.

(Coagulation value: 34) Pulp particles were obtained by substantially the same method as in Example 1 except that the pulp particles had a coagulation value of 34.

From the aqueous dispersion containing the thus obtained pulp particles 1.62.9 (solid content) and aromatic polyamide fibers (Teijin Co., Ltd. Cornex, fineness 1.5 denier) i and oB cut in 7 order, a Tarapy standard sheet was prepared. When paper was made using a machine, a sheet with good paper-making properties and good texture was obtained.

This sheet was hot pressed at 270° C. and 200 kg/cm20 to obtain paper with a thickness of about 130 μm.

The properties of this paper were as follows, all of which were excellent.

Example 11 Pulp particles were obtained in exactly the same manner as in Example 1 except that precipitants having various coagulation values were used.

Table 2 shows the paper-making properties of the pulp particles and the dielectric breakdown voltage of paper obtained from the pulp particles in the same manner as in Example 1.

No., C, and d are papers made from pulp particles obtained by the method of the present invention, and the others are comparative examples.

Cases a and b are cases in which the coagulation value is too small. This results in a poor sheet, and the dielectric breakdown voltage is also low.

e+f is an example of a case where the coagulation value is too high, and the produced pulp particles are agglomerated and welded, and although a sheet with good appearance is obtained, the dielectric breakdown strength is extremely low.

e and ci were obtained by the method of the present invention, and both paper formability and dielectric breakdown voltage were satisfactory.

Example 12 In Example 1, 4,4'-bis(trimellidoimide)diphenyl ether was used instead of 4,4'-bis(trimellidoimide)diphenylmethane, and 4,4'-diphenyl ether diisocyanate was used instead of 4,4'-diphenylmethane diisocyanate. Pulp particles were obtained in exactly the same manner as in Example 1, except that .

When paper was made using these pulp particles in the same manner as in Example 1, water drained well from the paper-making wire mesh, papermaking properties were good, and the resulting sheet had good formation. The properties of the paper obtained by hot pressing in the same manner as in No. 1 were as follows, and all were satisfactory.

Tensile strength 5.6 to 9/mm2 Elongation: 4.0 Dielectric breakdown strength 31 KV/醋

[Brief explanation of drawings]

FIG. 1 is a triangular diagram showing the mixing ratio of imidodicarboxylic acid, isophthalic acid, and terephthalic acid, and the shaded area represents the composition of the carboxylic acid mixture used in the present invention.

Claims (1)

[Claims] The compound is composed of 14,4'-bis(trimellidoimide)diphenylmethane and/or 4,4'-bis(trimellidoimide)diphenyl ether and isophthalic acid and/or terephthalic acid, the composition of which is shown by diagonal lines in FIG. carboxylic acid mixture within the range specified above, and 4,4'-diphenylmethane-
Pulp particles whose main wood component is aromatic polyamideimide obtained by subjecting diisocyanate and/or 4,4'-diphenyl ether diisocyanate to a thermal reaction. It is composed of 24,4'-bis(trimellidoimide)diphenylmethane and/or 4,4'-bis(trimellidoimide)diphenyl ether and isophthalic acid and/or terephthalic acid, and its composition is within the shaded range in Figure 1. A N-methyl-2-pyrrolidone solution of an aromatic polyamide obtained by subjecting a carboxylic acid mixture to a heating reaction with 4,4'-diphenylnocundiisocyanate and/or 4,4'-diphenyl ether diisocyanate has a coagulation value of 25. ~40, N-methyl-
Water with adjusted concentration of 2-pyrrolidone and N-methyl-2-
Introduced into a precipitant consisting of pyrrolidone while stirring,
A method for producing pulp particles, characterized by precipitating them as fine particles.