JPS619458A - Preparation of aromatic polyamide molding - Google Patents

Abstract

PURPOSE:To obtain the titled molding having excellent moldability by the specified treatment of a molding made by molding with heat an aromatic polyamide together with sulfolane to remove the sulfolane. CONSTITUTION:0.1-2,000wt% refined and dewatered sulfolane and, if necessary, a stabilizer, a molding assistant, etc. are added to an aromatic polyamide which contains the repeating units of formula I [where Ar1-2 each are a bivalent group such as an aromatic or aromatic heterocyclic compound which may be substituted by a (cyclo)alkyl, an aryl, a halogen, etc.] and has a glass transition point of 150-400 deg.C and a logarithmic viscosity of 0.5 or higher, and this composition is molded with heat to give an aromatic polyamide molding. Then this molding is treated at a temperature from room temperature to 300 deg.C in an inert gas or in a liquid which is compatible with sulfolane and does not dissolve an aromatic polyamide to remove the sulfolane remaining in the molding.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for molding aromatic polyamide.

[Conventional technology] In the electrical and electronic industries, as the usage conditions of products become more diverse, products are required to be smaller, lighter, faster, and use energy more efficiently. Similar challenges have been imposed in the field due to the rise in energy prices, and in order to achieve these goals and challenges, aromatic polyamides have attracted attention because of their excellent heat resistance and mechanical properties. Collect insulating film, printed wiring board, and bearings.

It is beginning to be used in the form of backings, gears, cams, piston rings, cloth, etc.

However, because aromatic polyamide has excellent heat resistance and mechanical properties, that is, because it is a thermoplastic resin with a high glass transition temperature, melt molding of aromatic polyamide is extremely difficult.

Conventionally, various methods of molding aromatic polyamides have been devised. For example, as a processing method using an amide solvent that has good affinity with the polymer (4-!j
No. 86442, JP-A-49-88443, JP-A-51
- IH83, JP-A-51-71348, JP-A-5
No. 1-1221513, JP-A-51-12218? issue,
JP-A-53'-123455, JP-A-54-1198
No. 8, JP-A No. 53-133537,
), and as an addition method using concentrated sulfuric acid as a solvent (
Unexamined Japanese Patent Publication No. 1973- +312<7, Unexamined Japanese Patent Publication No. 51-1836
No. 3.

JP-A No. 54-132874, etc.), and methods of increasing solvent solubility by introducing substituents into the polymer skeleton (JP-A No. 5-81854, JP-A-53-45238).
etc.) are known.

[Problems to be Solved by the Invention] Although these methods of molding aromatic polyamides facilitate the molding of the polymers, they have the same drawbacks as the other methods.

First, in the method using an amide solvent, it is extremely difficult to remove the solvent from the molded product because it has good affinity with the polymer. Next, the method using concentrated sulfuric acid has the same difficulties as amide solvents, but 11 is replaced by M4fl! of the acid itself! It is more problematic than amide-based solvents due to the added properties, properties, and hydrolytic effects. Furthermore, the method of introducing substituents into the polymer skeleton results in the loss of chemical resistance, which is a characteristic of the polymer.

As a countermeasure against these problems, for example, in JP-A-57-179225, a coagulation bath using silicone oil or mineral oil must be used to remove the solvent from the molded product of the solvent having good affinity with the aromatic polyamide. Therefore, these oil components penetrate into the molded product and impair the performance of the molded product. Furthermore, in JP-A-57-180837, an amine compound is used as a solubilizing agent for dissolving aromatic polyamide in a solvent. These amine compounds remain in the molded product and deteriorate the performance of the molded product.

[Means for Solving the Problems] The present inventors investigated the processing and molding method of aromatic polyamide and found that if sulfolane was used as a processing aid, the molding processability was extremely good. and completed the present invention.

The present invention relates to a method for producing an aromatic polyamide molded article, which is characterized by thermoforming an aromatic polyamide in the coexistence of sulfolane.

The aromatic polyamide has a glass transition temperature of 150
in the range of °C to 400'C, especially 200°C to
It is preferable that the temperature is in the range of 350°C from the viewpoint of moldability, and the one whose logarithmic viscosity (described later) is 0.5 or more is desirable from the viewpoint of chemical resistance, heat resistance, mechanical properties, etc.

Aromatic polyamides suitable for use in the present invention are those having repeating units of general formula (I).

111 In formula (I), Arl and Ar2 are each as follows; 3. Taste.

Arl is a divalent group consisting of an aromatic compound, a heteroaromatic compound, or a combination thereof, and is further substituted with an alkyl group, a cycloalkyl group, an aryl group, an alkoxy group, a halogen atom, etc. Also good.Also Ar
2 is a group similar to Arl, which is the same as or different from l.

To explain Ar1 and Arc in L in more detail, each of them is a divalent group consisting of an aromatic compound, a group of a heteroaromatic compound, or a combination thereof. When two or more of these groups are combined, for example, they are directly bonded through carbon-carbon bonding, or alkylene bonded.

-N -, -N -, -5i -, -0-5i-0-1
'l R etc. may be bonded to each other.

(R is an alkyl group or a cycloalkyl group here.

It is an aryl group. In addition, when two R's are bonded, they may be different groups.) The sulfolane used in the present invention is a commercially available commonly available
The produced sulfolane is sufficient, but in order to maintain the quality of the molded product, it is necessary to use known sulfolane purification methods (for example, A,
Weissberger's Organic 5olv
ents.

(3rd, ed.)) is preferred. In addition, stabilizers, molding aids, etc. may be added to this sulfolane to improve the performance of the molded product, or furthermore, a mixing aid for sulfolane and aromatic polyamide may be mixed therein. good.

Next, the mixing ratio of the aromatic polyamide and sulfolane in the present invention is changed as appropriate depending on the purpose of molding and a more suitable mixing ratio is adopted, but generally it is 0.1% to 2500% by weight of the aromatic polyamide. %, preferably from 1% to 2000% by weight.

As the molding method of the present invention, conventionally known wet or dry molding methods can be employed, and sulfolane is removed and recovered from the molded product obtained by these molding methods, if necessary.

In the wet molding method, the boiling point at normal pressure is
Although aromatic polyamide is not dissolved in 1- than OO'C,
The molded product is introduced into a liquid that is compatible with sulfolane and heated from room temperature to 300°C, preferably 70°C to 300°C, and the sulfolane is removed from the molded product. Next, in the dry molding method, the temperature is between room temperature and 300°C, preferably 1
00'C! The molded product is introduced into air, steam, or inert gas heated to a temperature in the range of ~300°C to remove sulfolane from the molded product. Furthermore, in either method, a stretching operation can be added to the molded product if necessary.

It is preferable to apply a temperature gradient to the liquid or gas heated to a temperature range from room temperature to 300°C, preferably 70°C to 300°C, used for removing sulfolane from the molded article, in order to increase the efficiency of removing sulfolane.

The molding temperature varies depending on the mixing ratio of aromatic polyamide and sulfolane and the applied molding method, but
It is preferably selected from the range of °C to 300 °C.

The molded product of the present invention is mainly intended for film-like products, thread-like products, and sheet-like products, but it can also be effectively applied to the production of other molded products such as thick molded products and rod-shaped products.

Hereinafter, specific examples of the present invention will be illustrated by way of Examples.

The main measurement methods used in the examples are as follows.

C - Polymer concentration in solution (g/100ml) t = solution flow time (seconds) to - solution flow time (seconds) , Ig/IOh! The temperature was 30"C.

Tensile strength 2 ASTM-0838, ASTM-0882 Tensile elongation: ASTM-De38. ASTM-0882
Izot impact strength: Strength and elongation of ASTIII-0258 (no notches) yarn: Measured using a strength tester manufactured by Instron, Inc., using a straight fiber.

[Example 1] An equimolar mixture of isophthalic acid and terephthalic acid, 50 parts by weight of an aromatic polyamide prepared from toluylene diisocyanate (8o/20) (ηinh = 1.7), and 100 parts by weight of sursulan the mixture with 250°
A film having a thickness of 105 mm was obtained by extruding it through a T-die and stretching it in a nitrogen slag heated to 170°C. The residual sulfotene in this film was 2.5%. Therefore, when the film was further stretched in a water bath at 80° C. to remove sulfolane, a film having a thickness of 92 fibers was obtained, and the amount of residual sulfolane was 0.3%. The tensile strength of the obtained film was 933 kg/c+n2
, the tensile elongation was 23%.

[Example 2] 50 parts by weight of an aromatic polyamide (ηinh = 2.5) obtained from an equimolar mixture of isophthalic acid and terephthalic acid and toluylene diisocyanate (80/20),
A mixture with 200 parts by weight of purified and dried sulfolane,
A thread-like product was obtained by extruding from 00'C and sufficiently stretching in nitrogen gas heated to 220C. The obtained filament was further stretched in a water bath at 85°C to obtain a fineness of 2.
．． A yarn having a denier of 5, a strength of 2 g/d, and an elongation of 15% was obtained.

[Example 3] Isophthalic acid and toluylene diisocyanate (80,
,”20), aromatic polyamide (ηinh
= 1.8) A mixture of 100 parts by weight and 50 parts by weight of sulfolane containing 31% triphenyl phosphite was extruded through a T-die at 280°C into nitrogen scum heated to 260°C. Then, I made a sheet-like material with a thickness of 1. By treating the t-1 sheet in a water bath at 80 DEG C., 7.3% of the remaining sulfolane was removed from the sheet. b1) The tensile strength of the sheet is 735kg/C
ff12. Tensile elongation is 35%, Izod impact strength is 18
kgcm/cm.

[Example 4] From a mixture of isophthalic acid and terephthalic acid in a weight ratio of 1:3 and 2.41 ylene diisocyanate, 11
aromatic polyamide (ηinh = L, 5) 10
0 parts by weight and 5 parts of barium stearate as a molding aid.
A mixture containing 10% by weight of purified sulfolane was extruded at 310° C. to obtain a molded product. The tensile strength of the obtained molded product was 764 kg/Cff12. Tensile elongation is 28%, Izod impact strength is 15kgCff1/
It was Cl11.

[Example 5] Aromatic polyamide obtained from isophthalic acid dichloride and metaphenylene diamine (ηinh -1,6)
A mixture of 100 parts by weight and 15 parts by weight of sulfolane 30
A 1.5 mm thick sheet was obtained by extrusion at 0°C into α-methylnaphthalene heated to 150°C. What is the tensile strength of the obtained sheet? 24 kg/Cff
12. Tensile elongation is 31%, Izotsu impact strength is 16kg
cm/cm.

[Comparative example 1] The test was conducted according to JP-A-57-179225.

50 parts by weight of an aromatic polyamide (ηinh = 2.5) obtained from an equimolar mixture of isophthalic acid and terephthalic acid and toluylene diisocyanate (80/20);
After mixing and dissolving 500 parts by weight of N-methyl-2-pyrrolidone, the solution was heated to 120°C and stirring was continued for 3 hours to prepare an aromatic polyamide dope. This dope was defoamed by a reduced pressure method. Next, the prepared silicone oil (trade name: Silicone KFfl14, manufactured by Shin-Etsu Silicone Co., Ltd.) was extruded while being stretched into a coagulation bath heated to 130'C, and further washed with toluene to obtain a thread. The fineness of this yarn is 2.2 denier and the strength is 2.
．． 48/d, and the elongation was 5%.

[Comparative example 2] Tested according to JP-A-57-180637.

A molar mixture of isophthalic acid and terephthalic acid, 50 parts by weight of an aromatic polyamide prepared by toluylene diisocyanate (80/20) (ηinh = 2.5), and 350 parts by weight of N-methyl-2-pyrrolidone. After mixing and dissolving, 5 parts by weight of n-hexylamine and 10 parts by weight of ethylenediamine were gradually added to prepare an aromatic polyamide tope. While keeping the obtained dope at 25°C,
1-n-methyl-2-pyrrolidone I previously prepared
The fibers were spun in an aqueous coagulation bath at 70°C in which Q trr J % and 301% calcium chloride were dissolved. The fineness of the obtained yarn was 2.8 denier, the strength was 1.5 g/de, 11
11 degrees was 4%.

[Effects of the Invention] According to the method of the present invention, since sulporan, which is a solvent that hardly dissolves aromatic polyamide at room temperature, is used,
By treating with a solvent that is compatible with sulfolane and does not dissolve the aromatic polyamide, or by treating with an inert gas, sulfolane can be removed from the molded product very easily and the original properties of aromatic polyamide can be maintained. A molded product can be obtained.

Claims (1)

[Scope of Claims] 1) A method for producing an aromatic polyamide molded article, which comprises thermoforming aromatic polyamide in the coexistence of sulfolane. 2) In order to remove sulfolane remaining in the molded product, the molded product is treated in a liquid that is compatible with sulfolane and does not dissolve in the aromatic polyamide in a temperature range from room temperature to 300°C. the method of. 3) The method according to claim 1, wherein the molded product is treated in an inert gas at a temperature ranging from room temperature to 300° C. in order to remove sulfolane remaining in the molded product.