JPS5929682B2 - Method for producing pulp-like particles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel method for producing bulk particles of heat-resistant aromatic polyamide.

Conventionally, natural pulp has been the most well-known bulp-like particle used in paper, but recently bulp-like particles obtained from synthetic polymers have been used for electrical purposes due to their excellent heat resistance and electrical insulation properties. It has started to attract attention as a material for insulating paper.

Pulp-like particles made of these synthetic polymers are produced by stirring a polymer solution in a large amount of precipitant, such as glycerin, or by discharging the polymer solution from an orifice-like nozzle at high speed and then beating it. Several methods have been proposed. However, all of these methods involve regenerating the polymer once obtained, and they all require a large amount of dissolving solvent, and also require a large amount of precipitant or spinning process.
It has drawbacks such as requiring complicated processes such as a beating process. In addition, when the pulp-like particles obtained in this way are processed and used as electrical insulating paper, they have poor impregnation properties, and furthermore, during paper making, they have poor water removal properties and a poor yield of pulp particles, making them uneconomical. It also has The present inventors have carried out extensive research in order to obtain bulp-like particles without these drawbacks, and as a result, in a mixed solvent system with a certain specific composition,
It has been discovered that by carrying out polymerization in the presence of short fibers, as the polymerization progresses, pulp-like particles connected to the short fibers and having excellent paper-making properties can be obtained, and furthermore, pulp-like particles obtained in this way can be obtained. The present invention was completed based on the discovery that the mechanical properties of the paper obtained by the conventional method are superior to those of the paper obtained by the conventional method.

That is, the present invention provides an aromatic diamine represented by the following formula [1] and/or [2] and an aromatic dibasic acid halide represented by the formula [3], or an aromatic amino acid halide represented by the formula [4]. In producing an aromatic polyamide polymer by condensation polymerization of a carboxylic acid derivative in a solvent, 40 to 85% by volume of an amide solvent consisting of one or more types that dissolves at least 10% by weight of the polymer. , a) which is compatible with the amide solvent and does not substantially dissolve the polymer;
aliphatic ether b) alkyl ester of aliphatic carboxylic acid c) one or more nonsolvents selected from the group of aliphatic halogenated hydrocarbons 60
The polymerization reaction is allowed to proceed in the presence of short fibers in the reaction system under high stirring (applying high shear force) in a mixed solvent with 15% by volume, and as the reaction progresses, the polymerization reaction is coupled to the short fibers. The present invention relates to a method for producing bulp-like particles, which is characterized in that they are precipitated as bulp-like particles that can be made into paper.

[However, in formulas [1L [2L] [3] and [4], R is hydrogen,
A lower alkyl group having 1 to 5 carbon atoms, a methoxy group, an ethoxy group, or a halogen atom, and X is -CH2-, -0
-, -CO-, -SO2-S-, and Y are halogen atoms.

The heat-resistant aromatic polyamide polymer referred to in the present invention means that a considerable portion of the main chain is composed of aromatic rings and has a softening point of at least 150°C or higher, preferably 250°C or higher, preferably at least 150°C or higher. means a polymer whose physical properties do not change significantly even if it is used for a long time in air at a temperature of 180° C. or higher.

Examples of such polymers include the following. (1) Aromatic polyamide obtained from a dicarboxylic acid having an aromatic ring, preferably a highly active derivative such as an acid halide, and a diamine having an aromatic ring: As the aromatic diamine, the above formulas [1] and [2] ] Aromatic diamines represented by, for example, metaphenylene diamine, paraphenylene diamine, tolylene diamine, 4,4-diaminodipheniether, 4,4'-diaminodiphenylsulfon, 4,4'-diamino Examples include diphenylmethane.

Examples of the dicarboxylic acid having an aromatic ring include terephthalic acid, isophthalic acid, and nuclear-substituted derivatives thereof. These aromatic diamines or aromatic dibasic acid dihalides, etc. may be composed of only one type of each, or may be a mixture of two or more types, but in order to obtain bulp-like particles with a high degree of polymerization, The molar ratio of the aromatic diamine component and the aromatic dibasic acid component is set to substantially equimolar, that is, 0.
．． The molar ratio of aromatic diamine component/aromatic dibasic acid component is preferably 95 to 1.05, preferably 1.0.
(2) Aromatic polyamide obtained by activating and condensing an aminocarboxylic acid having an aromatic ring: For example, as the aminocarboxylic acid, a polyamide containing only one type of aminocarboxylic acid, meta-aminobenzoic acid, or aminomethylbenzoic acid is used. It may be a homopolymer or a copolymer of two or more types of aminocarboxylic acids.

(3) Aromatic polyamides copolymerized with the above (1) and (2): Typical examples include polyamides consisting of three components: metaphenylene diamine, isophthalic acid cyclolade, and paraaminobenzoic acid chloride hydrochloride. It will be done.

The amide solvents used in the present invention include N,N-dimethylformamide, N,N-dimethylacetamide, N-
Methyl-2-pyrrolidone, N-acetylpyrrolidine, N
-Methyl-ε refers to a series of aliphatic carboxylic acids typified by ε-caprolactam, hexamethylbosvortriamide, tetramethylurea, etc., and dialkyl-substituted amides such as phosphoric acid.

These solvents may be used alone or in the form of a mixture of two or more, but in any form they must be capable of dissolving at least 10% by weight of the resulting aromatic polyamide; in the case of a mixture, Even if each of them does not have the above-mentioned dissolving power, it is sufficient that the mixture has the above-mentioned dissolving power. The non-solvent used in the present invention is compatible with the above-mentioned amide solvent and does not substantially dissolve the resulting aromatic polyamide,
It also refers to monomers that have low reactivity with aromatic diamines and aromatic dibasic acid dihalides.

Here, "substantially not soluble" means that the solubility is 1% by weight or less when the polymer is added and stirred at room temperature. Examples of such non-solvents include aliphatic symmetrical and asymmetrical ethers such as diethyl ether, diisopropyl ether, dibutyl ether, and ethylpropyl ether; ethers such as dioxane; and lower fatty acid esters such as ethyl acetate, butyl acetate, and propyl acetate. , methylene chloride,
Examples include halogenated hydrocarbons such as chloroform and carbon tetrachloride. The mixing ratio of the above-mentioned amide solvent and non-solvent varies depending on the structure of the polymer and the implementation conditions such as the combination of solvents, but the amide solvent is 40-85% by volume and the non-solvent is 60-15% by volume. It is preferable that there be.

The degree of polymerization of the polymer obtained as pipe-shaped particles must be measured at least by the method described below in order to make paper from the pipe-shaped particles and obtain paper with excellent mechanical properties, especially tensile strength and tear strength. An intrinsic viscosity value of 0.5 or more is required. If the ratio of the amide solvent is less than 40% by volume, the solubility of the polymer decreases, and precipitate particles are formed before the intrinsic viscosity rises to 0.5 or more. Even if it were obtained, it would not be possible to obtain paper with excellent mechanical properties.

On the other hand, if the content of the amide solvent exceeds 85% by weight, the ratio of precipitate formation decreases, and at the same time, a slurry-like solution with high viscosity is formed, resulting in disadvantages such as difficulty in separating bulp-like particles. The polymerization reaction in the present invention proceeds in the same manner as so-called low-temperature solution polymerization, and as the reaction progresses sufficiently, the solubility of the polymer decreases and the formation of precipitate begins. In order to generate bulp-like particles that are water-based and have good mechanical properties when paper is made, it is necessary to It is necessary to use high speed agitation to impart high shear forces to the polymer.

That is, by applying a high shearing force to the polymer, a precipitate is formed as branched fifurlic pipe-shaped particles. The degree of stirring required for this purpose depends on equipment factors such as the shape of the polymerization tank and the shape of the stirring blade, and the dissolving power of the mixed solvent used (i.e., the ratio of amide solvent in the mixed solvent).
Although it is not possible to make a general rule because it differs depending on the When the ratio of amide solvent in the mixed solvent is low, the rate of precipitation increases, so it is necessary to apply higher shearing force, so it is necessary to select the stirring device and conditions with this in mind. be. Specifically, for example, as shown in the examples,
In the case of a device in which a cylindrical stirring tank is equipped with paddle-shaped stirring blades, bulp-like particles yield paper with excellent paper-making properties and mechanical properties under stirring conditions that satisfy the following formula [5] experimentally and empirically. can be obtained.

However, 0.4D≦d<D What about d? The average width of the stirring blade in the direction perpendicular to the stirring axis is expressed in units, D is the average inner diameter of the stirring tank (CTrL), C is the proportion of the amide solvent in the mixed solvent used, and 0.
4≦C≦0.85, and Q is the number of rotations per minute of the stirring blade.

When the agitation is in a range that does not satisfy formula [5], the precipitated polymer particles are spherical or lump-like, making it impossible to make paper, or even if paper can be made, it is difficult to make paper by machine. The physical properties of the product are so bad that it becomes practically unusable. The ratio of short fibers to the resulting polymer is preferably 10 to 80 weight percent of the short fibers and 20 to 90 weight percent of the resulting polymer.

When the proportion of short fibers is less than 10% by weight, the mechanical properties such as tensile strength and tear strength of the paper obtained by making paper from the obtained bulp-like particles are inferior, and furthermore, the paper-making properties (P water content) are reduced. . Furthermore, when the ratio of short fibers is 80% by weight or more, the entanglement between the resulting bulp-like particles decreases, and although the papermaking properties (water repellency) improve, the mechanical properties and impregnation properties of the resulting paper decrease, etc. cause. The short fibers used in the present invention are not particularly limited, except for those that rapidly dissolve and completely dissolve in the solvent during polymerization, or those that are extremely reactive with the solvent.
There is no problem even if the polymer partially dissolves during polymerization.

Examples of these short fibers include aliphatic polyamide fibers such as nylon-6, nylon 6,6, and nylon-6,10, polyester fibers typified by polyethylene terephthalate, polymetaphenylene isophthalamide, and polyvaraphenylene. Short fibers made of almost all synthetic polymers such as aromatic polyamide fibers such as terephthalamide can be used in the present invention, but in order to obtain paper with particularly excellent electrical and mechanical properties, short fibers made of polyethylene terephthalate are used. It is preferable to use short fibers, fibers made of polyparaphenylene terephthalamide, fibers made of polymetaphenylene isophthalamide, or short fibers having the same type of structure as those subjected to polymerization. The object of the present invention can be achieved if the single fiber fineness of the short fibers is 0.1 to 10 deniers, but 0.3 to 3.0 deniers is particularly preferable. In addition, the length varies somewhat depending on the fineness of the single filament of the staple fiber, but is 1 to 10 m/L, preferably 3 to 8 J.
i is good These short fibers can be made to exist in the polymerization system by adding and dispersing them in advance to a mixed solvent for polymerization, or by mixing them with polymerization raw materials and adding them during polymerization, etc., and by adding them all at once. Alternatively, divisional addition may be used in the method of the present invention. The degree of polymerization of the bulb-like particle polymer linked with short fibers obtained by the method of the present invention is measured at 3'C in 98% sulfuric acid, and is expressed by the following formula [6
] The intrinsic viscosity is 0.5 or more.

Intrinsic viscosity (η1nh) C: 0.59/100 CC 98% sulfuric acid The bulp-like particles obtained by the method of the present invention usually have a Canadian standard deep water degree of 5 to 700,
It is possible to easily make paper using a general-purpose paper machine in the form of bulk particles or in a state containing short fibers, and the paper obtained has excellent mechanical properties, heat resistance, electrical insulation, and electrical resistance. This is an extremely excellent insulating synthetic paper.

Next, details of the method of the present invention will be further explained with reference to Examples.

Example 1 In a cylindrical flask with an inner diameter of 102 and an internal capacity of 2000 m1 equipped with a paddle-type impeller with a stirring blade length (4) of 8.5 CTrL, N-methyl-2-pyrrolidone 720 WLt and 28
A mixed solvent was prepared by taking 0 ml of methylene chloride.

8.10 g of metaphenylenediamine was added and dissolved in this mixed solvent. Next, 41.89 short fibers made of polymetaphenylene isophthalamide having a single fiber fineness of 2.0 denier and a fiber length of 5.0 were added and dispersed. Thereafter, 15.23y of isophthalic acid chloride was added as a powder into the system while rotating the stirring blade at 7200 rpm. Approximately 3 minutes after the addition reaction, a precipitate was formed to form an opaque slurry. After continuing to stir for an additional 10 minutes, the contents were filtered to obtain 52.39 bulk particles. The Canadian standard freeness (according to the method of JIS-P-8121) of these bulb-like particles was 345. Further, the intrinsic viscosity was 0.74. This bulp-like particle 4.59 was dispersed in 31 water, passed through an 80-mesh wire mesh, and dried to make paper.
It was compressed using DG press pressure.

The physical properties of the obtained paper are shown in Table 1. Examples 2 to 5, Comparative Example 1 Papers were obtained using the same equipment and method as in Examples, but with different types and ratios of short fibers.

Its physical properties are shown in Table 1. Example 6 Using the same reaction vessel as in Example 1, 540 ml of N-methyl-2-pyrrolidone, . In a mixed solvent consisting of 180 ml of N,N-dimethylacetamide and 480 ml of dioxane, polyethylene terephthalate short fibers with a single yarn fineness of 2 denier and a fiber length of 4.3 are recommended.
- 23.7 g of diaminodiphenylmethane and 6.59 g of paraphenyl diamine were taken and stirred to dissolve and disperse them.

Next, stirring was performed at a high speed of 9,600 rpm, and 36.5 g of isophthaloyl chloride was added to carry out a polymerization reaction.
Approximately 2 minutes after the addition of isophthaloyl chloride, pale yellow bulp-like particles were precipitated. The Canadian standard freeness of the resulting bulb-like particles was 4801. After drying the pulp-like particles in the same manner as in Example 1,
Heat and pressure treatment was performed at 0° C. and 85 K'/d.

Table 2 shows the physical properties of the paper obtained. Table 2 Tensile strength 8.7Kv/d Tensile elongation 125% Tear strength: 840g (Elmendorf test) Dielectric breakdown voltage 42. IKV/1

Claims (1)

[Scope of Claims] 1. An aromatic diamine represented by the following formula [1] and/or [2] and an aromatic dibasic acid halide represented by the formula [3], or an aromatic diamine represented by the formula [4] In producing an aromatic polyamide polymer by condensation polymerization of a group aminocarboxylic acid derivative in a solvent, at least 10% by weight of the polymer
40 to 85% by volume of an amide solvent consisting of one or more of the above-dissolved amide solvents, and a) aliphatic ether that is compatible with the amide solvent and does not substantially dissolve the polymer b) aliphatic carbon Alkyl ester of acid c) One or more nonsolvents selected from the group of aliphatic halogenated hydrocarbons 60
The polymerization reaction is allowed to proceed in the presence of short fibers in the reaction system under high stirring (applying high shear force) in a mixed solvent with 15% by volume, and as the reaction progresses, the polymerization reaction is coupled to the short fibers. A method for producing pulp-like particles, which comprises precipitating the pulp-like particles into paper-formable particles. ▲There are mathematical formulas, chemical formulas, tables, etc.▼[1]▲There are mathematical formulas, chemical formulas, tables, etc.▼[2]▲There are mathematical formulas, chemical formulas, tables, etc.▼[3]▲There are mathematical formulas, chemical formulas, tables, etc.▼ 4
[However, in formulas [1], [2], [3] and [4], R is hydrogen, a lower alkyl group having 1 to 5 carbon atoms, a methoxy group,
It is an ethoxy group or a halogen atom, and X is -CH_2
-, -O-, -CO-, -SO_2-, -S-, and Y are halogen atoms. 2. The production method according to claim 1, wherein at least 80 mol% or more of the aromatic diamine is metaphenylene diamine, and at least 80 mol% or more of the aromatic dibasic acid halide is isophthalic acid chloride. 3. The manufacturing method according to claim 1, wherein at least 80 mol% of the aromatic diamine is paraphenylene diamine, and at least 80 mol% or more of the aromatic dibasic acid halide is terephthalic acid chloride. 4. The manufacturing method according to claim 1, wherein the ratio of the short fibers to the obtained polymer is 10 to 80% by weight of the short fibers and 20 to 90% by weight of the obtained polymer. 5. Claim 1, in which at least 50% by weight or more of the short fibers are short fibers made of polyethylene terephthalate.
Manufacturing method described in section.