JPS591818B2 - Thailand's history - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved method for producing a heat-resistant sheet-like product made only of wholly aromatic polyamide.

Conventionally, as a method for producing a sheet-like product made only of wholly aromatic polyamide, pulp-like particles (Fibrid) are formed by precipitating the polyamide from a wholly aromatic polyamide solution.
There is a known method of manufacturing electrically insulating paper by mixing paper with fully aromatic polyamide fibers formed separately, but such a method requires a special process of manufacturing the pulp-like particles in addition to the fiber manufacturing process. It is extremely disadvantageous industrially since it requires a process.

As a result of intensive studies to solve the problems of the conventional method, the inventors of the present invention found that undrawn yarns made of wholly aromatic polyamide polymers have a very slow crystallization rate and are easily crystallized under appropriate pressure and heating conditions. In addition, the unheat-treated drawn yarn of the same car assembly has a very fast crystallization rate under heating, and the undrawn yarn rapidly crystallizes and hardens at the temperature at which the undrawn yarn begins to soften. The present invention was achieved by discovering that the fibers of a wholly aromatic polyamide polymer have good mechanical properties. A heat-resistant sheet-like material characterized in that a web is formed by mixing the yarns with the yarns, and then heat-compression bonding is performed under conditions that cause the undrawn yarns to be thermally fused without being swollen with an aqueous solvent solution of both yarns. It is in the manufacturing method.

The wholly aromatic polyamide polymer used in the present invention is a wholly aromatic polyamide in which 80 mol% or more of its repeating units are m-phenylene isophthalamide, and the amine component is metaphenylene diamine and/or other aromatic diamine. is polycondensed using isophthalic acid and other aromatic dibasic acids or derivatives thereof as acid components.

Aromatic diamines used other than meta-phenylene diamine include para-phenylene diamine, benzidine,
・4' diaminodiphenyl ether, 4,4' diaminodiphenyl sulfone, etc. Highly active derivative acid halides are usually used as the acid component, and suitable aromatic dibasic acid halides include, in addition to isophthalic acid chloride, terephthalic acid chloride, 1.4-naphthalenedicarboxylic acid chloride, and 2.6-naphthalenedicarboxylic acid chloride. Chloride, 4,4'-piphenylcarboxylic acid chloride, 3-
Examples include chloroisophthalic acid chloride, bis(parachlorocarbonylphenyl) ether, and the like. To prepare the polyamide solution for spinning, the polymerization stock solution may be used directly, or
Alternatively, the polymer stock solution may be once poured into water or other poor solvent to precipitate the polymer, and after drying, it may be redissolved. Suitable solvents include organic solvents such as N-N dimethylformamide, N-N dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, hexamethylphosphoramide, and tetramethylurea, or soluble supporting soils. In addition, a solvent system in which an inorganic salt such as lithium chloride or calcium chloride is added to these solvents, or an inorganic solvent such as sulfuric acid, hydrogen fluoride, fuming sulfuric acid, chlorosulfuric acid, or polyphosphoric acid is used.

The concentration of the polymer in the solution varies depending on the copolymer composition, degree of polymerization, and spinning method, but is approximately 5 to 25% by weight.
is desirable. The unheat-treated drawn yarn used in the present invention is obtained by dry-spinning, wet-spinning, or dry-wet spinning the wholly aromatic polyamide solution, and then removing the solvent in warm water, or after spinning the wholly aromatic polyamide solution, preferably by 2 to 6 times. can be obtained by stretching 3 to 5 times and drying.

The undrawn yarn used in the present invention is preferably a fiber that has not been drawn at all, but it is also possible to use a fiber that has been drawn at a low magnification of 2 times or less. Further, the undrawn yarn and the unheat-treated drawn yarn do not need to have the same composition, and particularly for heat-fusible mating soil, using a copolymer as the undrawn yarn gives good results. A preferred example of the undrawn yarn is isofumelic acid chloride/terehumeric acid chloride di 90/10.
(molar ratio) and memephenylene diamine, and use polymethaphenylene isophenolamide as the unheated drawn yarn. The appropriate mixing ratio of both yarns is 1:9 to 9:1; too little undrawn yarn will result in insufficient thermal fusing ability, making it difficult to form into a sheet; If it is too small, the sheet strength will be insufficient and the sheet will not be usable. The mixed web of both yarns is heated under pressure using a heat press or a heat roll to form a sheet. In this case, the temperature is 200 to 350°C and the pressure is 50 kg.
/CrA or more is appropriate.

According to the present invention configured as described above, there is no need for special processes other than fiber production such as the production of bulb-shaped particles, and furthermore, the crystallization of the unheated drawn yarn, which will become the base fiber, is performed in the sheet forming process. Since it is carried out simultaneously with the heat-sealing of the threads, the usual heat treatment process can also be omitted, which greatly contributes to labor saving and cost reduction in the production of heat-resistant sheet products.
Example: Polyphenylene diamine and isofumeric acid chloride were solution-polymerized in dimethylacetamide.
Polymephenylene isofumeramide 2 (measured at 0°C)
A 9-denier undrawn yarn was obtained by dry spinning a polymerization solution containing 0% by weight, 93% by weight of calcium chloride, and 3% by weight of water using a nozzle with a pore diameter of 0.15 m and 200 holes.

While removing the solvent from this undrawn yarn in 90°C warm water,
After being stretched approximately 4 times, dried, and then crimped, the fibers were cut to a length of 50 mm to obtain a stable body consisting of oriented 2-denier fibers. On the other hand, a 5-denier undrawn yarn obtained by dry spinning from the same polymerization solution was desolventized in 90°C hot water, dried, crimped, cut into a length of 50 mm, and then made into a stable yarn. ) was obtained. Next, the stable material and (B) were mixed in a ratio of (A)/old) = 60/40 (weight ratio), and the web obtained through the carding process was crimped with a linear pressure of 120k9/(V7I) using a hot roll at 310°C. As a result, a nonwoven fabric having a basis weight of 30y/77Z'' and a thickness of 1.3mil was obtained.

The strength of this nonwoven fabric was 4.5 kg/1, and the elongation was 10%.

Claims (1)

[Claims] 1. Conditions under which undrawn yarns of wholly aromatic polyamide polymers and unheat-treated drawn yarns are mixed to form a web, and then the undrawn yarns are thermally fused without being swollen with an aqueous solvent solution of both yarns. 1. A method for producing a heat-resistant sheet-like product, characterized by carrying out a thermocompression bonding process below.