JPS6225800B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing aromatic polyamide synthetic paper with significantly improved heat resistance and chemical resistance. [Prior Art] Conventionally, natural pulp is the most well-known pulp particle used in paper production and is produced in large quantities. On the other hand, synthetic paper obtained from synthetic polymers has recently attracted attention as an electrically insulating paper because it has excellent properties such as heat resistance and electrical insulation. In particular, synthetic paper whose main component is aromatic polyamide such as poly(metaphenylene isophthalamide) has excellent heat resistance (Japanese Patent Application Laid-open Nos. 51-19804, 51-75179, and 52-30000).
(see issue), and is attracting particular attention as a heat-resistant insulating paper. For example, Japanese Patent Publication No. 43-20421 proposes a high-temperature-resistant synthetic paper suitable for electrical insulation that is made of an entangled mixture of granular mica and aromatic polyamide fibrids (pulp particles) that are not substantially fused. has been done. However, synthetic paper mainly composed of aromatic polyamide has poor acid resistance and
Chemical resistance such as alkali resistance and heat resistance such as dimensional stability at high temperatures are still not sufficient, and it goes without saying that if these drawbacks are improved, its industrial value will be increased. [Object of the Invention] The main object of the present invention is to improve the chemical resistance and heat resistance of synthetic paper whose main component is an aromatic polyamide polymer as described above. [Structure of the Invention] That is, the present invention provides: (a) An aromatic polyamide polymer solution containing a crosslinkable compound made of cyanuric acid or an isocyanuric acid derivative having an epoxy group in the molecule is placed in a precipitant that is stirred at high speed. (b) making paper using the crosslinkable compound-containing pulp particles; (c) crosslinking the obtained synthetic paper; This is a method for producing aromatic polyamide synthetic paper with improved chemical properties. In order to produce aromatic polyamide synthetic paper in the method of the present invention, a production method generally referred to as a wet papermaking method is employed. That is, pulp particles formed by introducing a solution of a polymer mainly composed of aromatic polyamide into a precipitant that is being stirred at high speed, either alone or in a mixture with short fibers, are wet-processed. A method of making paper into synthetic paper is used. In the production of such synthetic paper, the method of the present invention involves adding and mixing a specific crosslinking compound to a solution of an aromatic polyamide polymer to form pulp particles, and producing synthetic paper made using the pulp particles. By subjecting the synthetic paper to radiation treatment and/or heat treatment, chemical crosslinking is caused in the synthetic paper. Each component of the method of the present invention will be explained in more detail below. Aromatic Polyamide The aromatic polyamide used in the present invention has an acid component and a diamine component both of which are aromatic polyamides, and has at least 3% by weight or more at room temperature.
It refers to a polymer that preferably has a solubility of 5% by weight or more, forms a stable solution, and has the ability to form a film, and whose main chain composed of units represented by the following general formula is substantially aromatic. Refers to something consisting of a base. -HN- _Ar1 -NH-CO- _Ar2 -CO- and/or -NH-Ar-CO- In the formula, _Ar1 and _Ar2 are selected from the group of aromatic groups shown below. Ar：

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[Formula] _Ar2 :

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【formula】 〔Effect of the invention〕

According to the method of the present invention as described above, heat resistance is selectively improved without causing a significant decrease in mechanical properties compared to conventional synthetic paper, and electrical properties such as dielectric breakdown voltage are also improved accordingly. Ru. Furthermore, it has improved resistance to various chemicals, is hardly soluble in salt-containing amide solvents, and has an insoluble portion of 5% or more in concentrated sulfuric acid. [Examples] Examples of the present invention will be described in detail below. In addition, in the example, the part insoluble in 96% concentrated sulfuric acid was determined as a guideline for the degree of crosslinking.
mg was placed in a dissolution tube equipped with a stirring bar, 20 ml of 96% concentrated sulfuric acid was added, and the mixture was stirred at 25°C for 2 hours, filtered through a glass filter, washed and dried, and the weight of the insoluble portion was measured and expressed in weight %. Examples 1 to 4 Intrinsic viscosity 1.35 obtained by interfacial polycondensation method
60 parts by weight of poly(metaphenylene isophthalamide) powder (measured at a polymer concentration of 0.5 g/dl in NMP) was added to 940 parts by weight of N-methyl-2-pyrrolidone (NMP).
Parts by weight, 60 parts by weight of water, and 3 parts by weight of the crosslinkable compound shown in Table 1 below were dissolved in advance and dispersed in a mixed solvent cooled to about 5°C, and then heated to about 50°C to form a polymer. Completely dissolved. On the other hand, as a precipitant, NMP and water are mixed,
A precipitant with an NMP concentration of 35% by weight was prepared and the temperature was adjusted to 39°C. The precipitation device is a pipe agitation type that consists of a combination of a stator with a flute and a two-blade rotor in the form of turbine blades, and is equipped with a supply port for the precipitant and polymer solution, and a discharge port for the pulp particle slurry after precipitation. Using a continuous precipitator, the polymer solution and precipitant were simultaneously supplied at a flow rate of 0.5 kg/mm and a precipitant at a flow rate of 5 kg/mm, and a slurry of pulp particles was taken out from the outlet. The rotation speed of the rotor at this time was 7100 rpm. The resulting slurry of pulp particles was placed in a Nutstier type filter to separate most of the precipitant into a liquid, and then ion-exchanged water was supplied to thoroughly wash the pulp particles. From an aqueous solution containing 1.2 g (solid content) of the pulp particles thus obtained and 0.8 g of 1.5 denier poly(metaphenylene isophthalamide) fiber (registered trademark "Konex") cut into 7 mm pieces. When paper was made using a Tatsupi standard sheet machine, a sheet with good paper-making properties and good texture was obtained with good water drainage from the paper-making wire mesh. After drying this sheet, it was hot pressed at 270° C. and 200 kg/cm ² to obtain paper with a thickness of about 100 μm. Its physical properties and chemical resistance are shown in Table 1. Comparative Example 1 Example 1 without containing a crosslinking compound
Synthetic paper was obtained in the same manner as in 4. The physical properties and chemical resistance of this product are also listed in Table 1.

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Claims (1)

[Claims] 1. An aromatic polyamide polymer solution containing a crosslinkable compound made of cyanuric acid or an isocyanuric acid derivative having an epoxy group in the molecule is introduced into a precipitant that is being stirred at high speed to form pulp particles. production of aromatic polyamide-based synthetic paper with improved heat resistance and chemical resistance, characterized by forming paper using pulp particles containing a crosslinkable compound, and subjecting the obtained synthetic paper to a crosslinking treatment. Method. 2. The manufacturing method according to claim 1, wherein the aromatic polyamide is poly(metaphenylene isophthalamide). 3. The manufacturing method according to claim 1, wherein pulp particles containing a crosslinkable compound are mixed with heat-resistant staple fibers to form paper.