JPS61160413A - Synthetic fibril - Google Patents

Abstract

PURPOSE:Synthetic fibril useful as a raw material for an electrical insulating sheet, etc., having a specific particle size distribution by fiber classification, water leakness by Schopper-Riegler method, and improved paper making properties, providing a uniform paper-like sheet with improved formation. CONSTITUTION:A polymer such as aromatic polyamide, etc., obtained by subjecting terephthalic acid chloride, isophthalic acid chloride, and metaphenylenediamine to interfacial polymerization, etc., in a solvent is dissolved in N-methyl-2-pyrrolidone, etc., blended with a precipitating medium while rotating the solution by a rotor, etc., to give fibril. Then, it is beaten and released to give synthetic fibril having <=20wt% ratio passing through 150 meshes wire net, >=50wt% ratio not passing through 150 meshes wire net and passing through 24 meshes wire net, and <=10wt% ratio no passing through 24 meshes wire by fiber classification prescribed by JIS P8207, and 55-80 deg. SR water leakness by Schopper-Riegler method of JIS P2102.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a synthetic fibrid that has good paper-making properties and provides a paper-like sheet obtained by paper-making with good physical properties.

Prior art It has been known for a long time to produce synthetic fibrids from a polymer solution by a wet method, and the
No. 1, Japanese Patent Publication No. 37-5732, etc. describe synthetic fibrids and methods for producing sheets using the same.

However, fibrids obtained by these methods are
Paper-making properties, especially water drainage from paper-making steel, are poor, and it is difficult to obtain a uniform paper-like sheet with good texture, which is disadvantageous.

In order to eliminate these drawbacks, fibrids (pulp particles) made of aromatic polymers, which comply with JIS P8
The amount of 150-mesh gold steel passing through the sieving test specified in 207 is 30 to 80% by weight, and the average specific resistance value is s x 1o' to lo o x 1o
"Fibrids that are cx/i (#i Kaisho 51-965
No. 10), or 150 mesh gold steel passing through the sieving degree test is 5 to 30% by weight, and the average specific-excess resistance value is 5 X 1 G' to 100 X 1 O'cx
/ Fibrids that are I (JP-A-53-t6070
No. is proposed.

Purpose of the Invention As a result of various studies based on these findings, the present inventors have determined that the characteristics of the paper-like sheet made by Shoto Karasu are only the proportion of fine particles of fibrids and the value of the average specific p-overresistance. We found that in order to obtain a good paper-like sheet, it is important that the fibrids used for paper making have a specific particle size distribution and that the amount of ice charcoal falls within a specific range. The present invention was achieved by clarifying the correlation between the properties of fibrids and the properties of paper-like sheets obtained using the fibrids based on experiments.

Accordingly, an object of the present invention is to provide a fibrid which has excellent paper-making properties and which is used to make paper, and the resulting paper-like sheet has good physical properties.

Structure of the Invention The present invention is based on the 150-mesh gold steel passage in the 1 tL sifting test specified in JIS P8207.
150 mesh wire mesh does not pass through, but 24 mesh wire mesh passes through (things with a particle size of 24 to 150 mesh).
occupies more than 50% of the total weight, and 24% of the total weight is 10% of the total.
weight - or less, and the P water return specified by JIS P2102 is 55 to 80 @ by Schottsparrigler method.
It is a synthetic fibrid characterized by being within the range of SH.

The polymer forming the synthetic fibrids of the present invention is not particularly limited as long as it is a fiber-forming polymer soluble in an organic or inorganic solution, but in order to produce a heat-resistant paper sheet suitable for electrical insulation, etc. It is particularly preferred that the polymer is an aromatic polyamide.

Such aromatic polyamides include (a) a condensation polyamide of a dicarboxylic acid having an aromatic ring (preferably a highly active derivative such as an acid halide) and a diamine having an aromatic ring; for example, as a dicarboxylic acid,
Using terephthalic acid and/or isophthalic acid, metaphenylene diamine, 3.4'- or 4.4 as diamine
'-cya inodiphenyl ether.

3.4/- or 4,4/-diaminodiphenylmethane,
Homo 41J condensed using one or more types of quinlene diamine and N-methyl-paraphenylene diamine
There are amides and copolyamides, typical examples include
Polymetaphenylene inphthal 7mid, metaphenylene diamine and isophthal 11m! and copoly7mide with hyterephthalic acid, polyN-me'! - Luparaphenylentele 7 talamide and the like.

佽) A polyamide obtained by activating and condensing an aminocarboxylic acid having an aromatic ring; for example, a homopolyamide using para- or meta-aminobenzoic acid, paraamine methylbenzoic acid, etc. as the aminocarboxylic acid, or a combination of two or more kinds of aminocarboxylic acids. 7
Copolyamide of minocarboxylic acid (e) (a) (
Polyamide co-condensed with b); typical examples include metaphenylene amine and isophthalic acid pride.

An example is a copolyamide obtained by co-condensing three components of paraaminobenzoic acid chloride hydrochloride.

In order to produce fibrids from the above-mentioned polymers, a wet (precipitation) method as described in Japanese Patent Publication No. 35-1151, Japanese Patent Publication No. 37-5732, etc. can be adopted, but fibrids cannot be formed from a single polymer solution. As a precipitation device for this purpose, a continuous precipitation device that combines a stator of a specific shape and a turbine blade type cooler as described in Japanese Patent Application Laid-open No. 52-15621 is used. It is preferable to precipitate and solidify the polymer solution while applying a strong shearing action to the polymer solution.

At this time, the solvent for dissolving the aromatic polyamide may be an inorganic solvent such as sulfuric acid, chlorosulfuric acid, hydrogen fluoride, etc. N-methyl-2-pyrrolidone lNN'-dimethylformamide.

N N'-dimethylacetamide, dimethylfokilad.

Organic solvents such as tetramethylurea may be used, but among these, polar amide solvents are particularly preferred. Such a solvent may contain an inorganic salt such as calcium chloride, magnesium chloride, lithium chloride, etc. in order to improve the solubility of the solvent.

The concentration of the polymer solution used for precipitation varies depending on the type and degree of polymerization, the 45j1 of the solvent, etc., but is generally between 2 and 4.
Especially preferred is 5 to 15% by weight.

On the other hand, the precipitant is not particularly limited as long as it is a liquid that is a non-solvent for the polymer and has an affinity for the solvent in the polymer solution.
An aqueous solution containing at most % by weight is preferred.

According to the research conducted by the present inventors, fibrids produced by a wet method similar to the method described in Japanese Patent Publication No. 35-11851 have a particle size distribution (sieving result) of 6. It was found that the physical properties of the paper-like material after papermaking differed depending on the temperature).

For example, Table 1 shows the sieving test results, and the physical properties of paper-like sheets made using fibrids that differ only in degree of beating are determined by the degree of freshness of the fibrids, as shown in Figures 1 and 2. The tensile strength and elongation and dielectric breakdown voltage (B, D, v,) of the paper-like sheet change greatly.

Table 1 As is clear from Figures 1 and 2, there are some differences depending on the fibrids, but even if the particle size distribution is the same, the physical properties of the paper-like sheet after papermaking will differ if the charcoal is different.

On the other hand, the physical properties of paper-like sheets made from fibrids with different particle size distributions (sieving test results) are different even if F water reconstitution (beating cap 1 is the same).

This example is shown in fi-2 below.

Furthermore, from an industrial perspective, fibrids with too large P water return (Schottsparrigler process) are inconvenient during paper making, and the presence of large-particle fibrids results in poor formation of the paper-like material after paper making.

Therefore, in the present invention, as fibrids for paper making, in the sieving degree test specified by JIS P8207 K, the amount of fibrids that did not pass through the 150 mesh wire mesh was 20% by weight or less, and the amount that did not pass through the 80 mesh wire pan was 24% by weight.
IA passing portion.

Fibrids are selected that have 50% or more of 24 mm gold and copper that does not pass through, and 55 to 80" SR, preferably 60 to 75 degrees SR, according to the J4S P21U2-standard Jopper Rigler method. be done.

In other words, it is necessary that both the particle size distribution of fibrids and the ice charcoal specified by the sieving test results are within the above range, and if either of them is out of the range, the paper must have good papermaking properties and the paper after papermaking. Fibrids having the above-mentioned specific particle size distribution and freeness, for which good physical properties cannot be obtained, are disclosed in Japanese Patent Publication No. 35-11851 KIlli1.
When producing fibrids by a wet method based on the method of 51e, it can be obtained only by adopting extremely limited special conditions, and in general, the fibrids are removed from the precipitator, washed with water, dehydrated, and then sieved. It can be obtained by beating, disintegrating, or a combination thereof.

That is, in conventional general papermaking pretreatment, beating is performed after dissociation, but in order to obtain the fibrids of the present invention, it is preferable to reverse the order and perform dissociation after beating. For example, take out fibrids from a sedimentation machine, wash them with water, and dehydrate them.

After being beaten with a beater or a finer, it is fed to a disintegrator for disintegration processing.

Further, it is also possible to use a sieving machine to sieve fibrids of a specific particle size to adjust the particle size distribution, or to sieve after beating, and then further beat and disintegrate.

The synthetic fibrids of the present invention as described above are mixed with heat-resistant short fibers and made into paper.

It can be made into a paper-like sheet with excellent strength and elongation and electrical insulation.

Examples of heat-resistant short fibers include the following.

(&) Short fibers made of aromatic polyamide The aromatic polyamide is the same as described above, but polymetaphenylene isophthalamide fiber, polyparaphenylenetere-7-thalamide fiber, or fupolyamide fiber containing these as main components is particularly preferable. .

(b) Short fiber naphthalate polyesters made of naphthalate polyesters include (a) polyethylene-2,6-naphthalate and/or
or polyethylene-2,7-naphthalate.

(b) Ethylene-2,6-naphthalate unit/
Or a copolymer containing 85 moles or more of ethylene-2,7-naphthalate units.

can be given.

(e) Inorganic short fiber; For example, glass fiber, asbestos fiber.

Inorganic fibers such as rock wool, mineral cotton, mineral fiber, bauxite fiber, kayamate iron weave, boron-based fiber, potassium titanate fiber, magnesia fiber, voice car such as alumina, silicon trithide, etc. are used.

fd) Natural fibers or recycled fibers; e.g., wood, hemp, rayon, cellulose acetate) 11. Ml etc. can be mentioned.

Among these fibers, the aromatic polyamide fiber (a) is particularly preferred.

The ratio of fibrids and short fibers is fibrids 10
-90% by weight, short fibers can be appropriately selected within the range of 90-10% by weight.

The conventional wet paper making method can be used for mixed paper making, and the conditions for heating and pressing the paper sheet are a pressure of 50 to 500 Yu/min.
Preferably, the temperature is 230 to 320°C.

Effects of the Invention The synthetic fibrids according to the present invention as described above can be made into paper-like sheets with good paper-making properties and good texture, and the paper-like sheets obtained using the same have good strength and elongation, electrical insulation properties, etc. In good condition.

Therefore, this paper-like sheet is particularly useful as an electrical insulator (
Although preferred, the synthetic fibrids may also be described in, for example, JP-A-56-108180 and JP-A-57-1475.
When used as a raw material for friction materials such as those shown in No. 72, friction materials with excellent strength etc. are formed, and the synthetic fibrids can be used as inorganic powders and whiskers.

It can also be used as a binder for organic fibers and carbon fibers.

Example Next, an example of the present invention and a comparative example will be described in detail.

Examples 1-2. Comparative Example 1 5 mol parts of prephthalyl chloride, 95 mol parts of isophthalic acid chloride, and 7100 mol parts of metaphenylene diamide were mixed in detrahydrocufuran as a solvent in Japanese Patent Publication No. 47-108.
After separating and washing the interfacially polymerized polymer free of inorganic salts according to the method of No. 63, it was dissolved in N-methyl-2-pyrrolidone to make a solution of 12.5%. - Measured as beyridone solution: 1
．． It was 3.

On the other hand, a 30% aqueous solution of N-methyl-2-pyrrolidone was prepared and used as a precipitant.

A rotor having the structure shown in JP-A-52-15621! Rotation speed: 100 using a 150m+φ sedimentation device
1 volume part of the above solution, 30 parts of the precipitant while operating at
The polymer solution and precipitant were introduced in parts by volume to obtain fibrids whose main repeating unit was metaphenylene 7-talamide.

The Schopper P ice charcoal (beating degree) of the obtained fibrids was 61.5'SR, and the results of the sieving degree test were as follows.

150 mesh passing 6.3%80~iso
Metsu 7 Yu 7.8% 48-80 Metsu Yu
16°9% 24~48 mesh 37.2
32.8 pieces of fibrids that did not pass through 24 meshes were processed as a 0.7% slurry in a Niagara beater, and then processed twice as a KO, 5% slurry in a high-speed deintermer.

The charcoal of fibrids in each step, the sieving test results, and the fibrids in each step were sampled to obtain 2 ds + cut length 6 of polymetaphenylene inphthalamide fiber M (registered trademark "Konex").
The physical properties of a paper-like sheet mixed with U short fibers and fibrids at a ratio of 60/40 and then heated and pressed are shown in the table below.
It was a 3rd order.

Table-3・Examples 3-5. Comparative Examples 2 to 5 A polymer of polymetaphenylene isophthalamide having an intrinsic viscosity of 1.35 was dissolved in N-methyl-2-pyrrolidone.
A 12.5% solution was obtained. On the other hand, a 30% aqueous solution of N-methyl-2-pyrrolidone was prepared and used as a precipitant. Examples 1 to 2 were carried out using these polymer solutions and precipitants. Fibrids of polymetaphenylene inphthal 7mide were produced in the same manner as in Comparative Example 1.

This fibrid was passed through 150 mesh wire mesh (15
0 mesh JM lower) + 1so mesh wire mesh failure 80
Mesh metal mesh passing through (150-80 mesh), 80 mesh wire mesh not passing through 48 mesh 4ktAlh3a (
a o ~ 48 metshu).

48 mesh wire mesh does not pass through, 24 mesh wire mesh passes through m (4s to 24 mesh), 24 mesh wire mesh does not pass through (
24 metsunyu or more).

Disperse these under the same conditions (60% with a home mixer)
(dispersion for 3 minutes) to obtain fibrids of various types of F fisheries (Nyotsuba Rigler freeness). This is 2 denier, cut length 6, shoulder fiber 4 and these fibrids 6
Table 4 shows the results of mixing at a ratio of 0 and making paper.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between the freeness of fibrids and the dielectric breakdown voltage (B, D3.) of a paper-like sheet after papermaking, and Figure 2 is a diagram showing the relationship between the freeness of fibrids and the dielectric breakdown voltage (B, D3.) of a paper-like sheet after papermaking. FIG. 2 is a diagram showing the relationship between the tensile strength and elongation at break of a paper-like sheet.

Claims (4)

[Claims] (1) In the sieving degree test specified in JISP8207, the amount that passes through the 150 mesh wire mesh is 20% by weight or less, the amount that does not pass through the 150 mesh wire mesh and the amount that passes through the 24 mesh wire screen accounts for 50% or more by weight, and The amount that does not pass through the mesh wire mesh is 10% by weight or less, and J
A synthetic fibrid suitable for papermaking, characterized in that its freeness as defined by ISP2102 is within the range of 55 to 8°SR by the Schottper Rigler method. (2) The synthetic fibrids according to claim (1), wherein the fibrids produced by a wet method are subjected to beating and disintegration treatment to adjust the particle size distribution and freeness within the above ranges. (3) The synthetic fibrids according to claim (1), wherein the fibrids produced by a wet method are sieved to adjust the particle size distribution and freeness within the above ranges. (4) Fibrids produced by a wet method are beaten and sieved, and further beaten and disintegrated to adjust the particle size distribution and freeness within the above range. Synthetic fibrids.