JPS6016474B2 - Manufacturing method for aromatic polyamide molded products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel method for producing thin or thin aromatic polyamide molded articles such as films, filaments, and yarns having high strength and excellent heat resistance.

Conventionally, aromatic polyamides have a melting temperature of 40,000 or higher, so it is impossible to apply melt molding, which is commonly used for polyesters, polyamides, etc. A so-called wet or dry molding method is used in which the polymer solution is once dissolved in a polar organic solvent such as urea, and the solvent is removed by extruding this polymer solution through a nozzle, die, or orifice into a liquid or gas stream.

However, this method has the drawback that it requires an expensive solvent and also requires a large amount of expense for solvent recovery. Against this background, as a result of studies on low-temperature melting of aromatic polyamides, the present inventors first developed crystalline chains that can be melt-molded by appropriately treating aromatic polyamides with hexamethylphosphoramide or N-methyl 2-pyrrolidone. Manufactured the body and discovered scales (Mochito Sho 50-1126205, etc.)
.

The present invention relates to a method for molding these crystalline bodies.

That is, the gist of the present invention is to provide crystals formed from an aromatic polyamide polymer in which at least 75 mol% of the repeating structural units are m-phenylene isophthalamide, and hexamethylphosphoramide or N-methyl 2-pyrrolidone. The complex is melted at a temperature above its melting temperature and then extruded.

The present invention will be specifically described as follows.

An aromatic polyamide polymer in which at least 75 mol% of the repeating structural units are m-phenylene isophthalamide is brought into contact with hexamethylphosphoramide or N-methyl 2-pyrrolidone to dissolve or absorb the solvent. Then, the excess solvent is removed by vacuum drying at a temperature of 15,000 qo or less, preferably 80 qo or less. The crystalline lead body thus obtained exhibits a crystalline diffraction pattern, contains an appropriate amount of solvent, and exhibits a clear melting point. A crystalline rust body of a polymer is in the form of a powder or pellet at room temperature, and melts and softens above a certain temperature.

Above the melting temperature, it has a melt viscosity of 1 to 1 pipoise, depending on the degree of polymerization of the polymer and the amount of solvent present, and can be extruded. In this case, the amount of the solvent present is preferably 2.5 or less in molar ratio per repeating unit of the polymer. If the amount of solvent exceeds this amount, the plasticizing effect becomes significant, and although melt spinning is possible, it becomes the same as gel-grade yarn, and the structure formation of the undrawn product is close to that of wet spinning, and the strength is less than 1/d, and the yarn is spun. The speed also needs to be less than several tens of machines per minute, resulting in low productivity. Further, it is necessary for the crystalline key body to contain a solvent in a molar ratio of 0.5 or more for moldability. Examples of crystalline collar bodies made from a polymer and a solvent are as follows.

Methanol melting point Extraction solvent amount Hexamethylphosphoramide 120℃ 1.8 mol N
Methyl 2-pyrrolidone 103 1.7 The crystalline complex is extruded through a nozzle, T-die, at a temperature of 500 degrees or more, preferably 1 and 0 degrees or more of its melting temperature.

No particular coagulation step is required. Next, the material is shaped by winding it up in a single stroke or by passing it through a washing, stretching, drying, or hot stretching process without winding it up. Note that washing and stretching may be performed at the same time or in the reverse order. For example, in the case of fiber shaping, it is possible to extrude at a high yarn speed (100/min or more), and the undrawn yarn already exhibits a high degree of orientation.

Next, it is stretched 1 to 5 times in hot water of about 100 qo. At least 300℃ after drying in hot air or on heated rolls or boards
Fibers having yarn quality equal to or higher than yarns produced by conventional wet or dry methods by passing through rollers or heated ramps heated to preferably 330°C and crystallizing while stretching 4 times or less. can be obtained. The fibers after being hot-stretched three times have a strength of 7.5/d and provide highly aligned, highly crystalline fibers. In the present invention, a coagulation layer is not required, and the use of metal salts, which are commonly used in the molding process of aromatic polyamides, is not required.

Therefore, there is no need for the expense of recovering metal salts from paper filaments and cleaning fluids, and the amount of organic solvent used is small, which is extremely advantageous economically. The aromatic polyamide targeted by the present invention has a relative viscosity (measured from a 30001% solution with 95% concentrated sulfuric acid) of 1.5 to 5.5 and has a repeating structure manufactured by solution polymerization or interfacial polymerization. unit of 75
At least mol % of the compound is composed of m-phenylene isophthalamide.

If the English polymerization component exceeds 25 mol %, the crystallinity of the crystalline body formed will be markedly reduced, making it unfavorable for handling. Components to be copolymerized as necessary include amine components such as P-phenylene diamine, benzidine, 44 diaminodiphenyl ether, and 44' diaminodiphenylsulfone, and terephthalic acid chloride, 114 or 2 diaminodiphenyl sulfone as brewing components.
- 6-naphthalene dicarboxylic acid chloride, diphenyl ether 44' dicarboxylic acid chloride, and amide/benzoic acid chloride can be mentioned.

EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to the Examples. Example 1 Polym-phenylene isophthalamide polymer obtained by polymerization in dimethylacetamide by a known method (el=
The polymer powder obtained by coagulating the solution of 3.5) in water at a temperature of 4 pm or below and drying at a temperature of 8,000 pm or below was dispersed in hexamethylphosphoramide at a volume of 1 by weight, and heated at 100 pm C. The temperature was raised using a rope pestle to melt it.

When this solution was cooled to 2yo, it became a white gel-like substance, and its X-ray diffraction pattern showed that of a complex crystal. The temperature of the gel-like material was raised again to 80 qo, and vacuum drying was performed at 1 Yanagi Hg for 2 hours. The solvent/polymer molar ratio of this dried product was 1.3, and the melting point was 12 to 0. 65k9 at 150℃ through a 1q spinneret (each hole is circular and 0.5 diameter side)
/ Extruded under pressure.

L/D of the nozzle is 5. The iron thread was wound up at a speed of 200/min. This drawn yarn was fed into a 3w long washing bath at a rate of 20/min, and was washed at 100qC while being taken up at 30/min. The sound of the sound was extended. The film was then passed through a drying roller at 150° C., and subjected to a stretching heat treatment while being stretched twice on a 32 pi hot plate. The yarns given a total draw ratio of 3 times had good appearance and gloss, and the physical properties of the filaments were as follows. Denier 2. Melon strength
6.0 kno d elongation
28% initial modulus
120 t/d Example 2 The same polymphenylene isophthalamide polymer powder as in Example 1 was dissolved in 30 qo of N-methylpyrrolidrine at a volume of 1 volume by weight.

This solution was vacuum dried at 40 oo for 2 hours under reduced pressure of 1 kg Hg. The solvent/polymer molar ratio of the obtained dried product was 1
-5, and the X-ray diffraction pattern was that of a collar crystal consisting of polyphenylene isophthalamide and N-methyl 2-pyrrolidone. The melting point was 103°C. l of this dried material
It was extruded under pressure at 130° C. through a Q-grade thread cap (each hole was circular and had a diameter of 0.5 mm). L/D of the nozzle is 5.
The paper thread pressure at this time was 65k9/m. Grade thread is 20
It was wound up at a speed of 0 m/m. The undrawn yarn was fed into a washing bath at 3 times a minute at a rate of 20 minutes, and washed at 100 degrees per minute.
Stretching was carried out at 1.9 m/min with a take-up roll. Then, it was passed through a drying roller of 150 qo, and
Stretching heat treatment was carried out while carrying out a 3-fold stretching operation on a heating slope of qC, giving a total stretching ratio of 4.5 times. The yarn had good appearance and gloss, and the physical properties of the filament were as follows. Denier
Just over 2.2d. degree 6.5 evening/
d Elongation 30% Initial modulus 110/d Example 3 The same polyphenylene isophthalamide used in Example 2 and N-
13. Rin body powder consisting of methyl 2-pyrrolidone was obtained from T-die.
Extruded at 0q0.

The extruded sheet was brought into contact with a metal roller with a surface temperature of 20 qO, and then stretched 4 times between rollers in an atmosphere of 150 pm. 1. Stretched sheet in 10,000 ml of water
After drying at 150 qo, heat treatment was performed on a hot plate at 320 qo. The resulting sheet was transparent and 30 mm thick. The physical properties of the sheet were as follows. Machine direction Lateral direction

Claims (1)

[Claims] 1. A crystalline complex formed from an aromatic polyamide polymer in which at least 75 mol% of the repeating structural units are m-phenylene isophthalamide and hexamethylphosphoramide or N-methyl 2-pyrrolidone is heated at a temperature higher than its melting temperature. A method for producing an aromatic polyamide molded article, which comprises melting and then extrusion molding.