JPH04209821A - High-strength fiber or film of aromatic copolyamide having side-chain carboxyl group - Google Patents

Abstract

PURPOSE: To obtain the subject fiber excellent in adhesive property and useful as a fiber-reinforced composite material by forming it with an aromatic polyamide having a fiber-forming molecular weight and containing specific recurring units. CONSTITUTION: This fiber is obtained by producing a spinning dope consisting of an aromatic polyamide having a fiber-forming molecular weight and consisting of recurring units expressed by formula I (X is 1,4-phenylene; Z is approximately 2-15 mol%), formula II and formula III and concentrated sulfuric acid in at least 15 wt.%, spinning the dope into a coagulation bath such as water through an inert fluid layer and taking a coagulated fiber from the bath.

Description

[Detailed description of the invention]

0001

[Technical background of the present invention] The present invention provides a side chain carboxyl group (
pendant carboxyl group
The present invention relates to a p-aramid high strength fiber having the following properties. The presence of these side groups imparts properties to the polymer and fibers or films such as increasing reactivity, improving adhesion to the matrix material in reinforced composite structures, or imparting other properties. provide. [0002] The industrial importance of woven composite materials has long been recognized. While the adhesion between some reinforcing fibers and the polymeric matrix is excellent, others require so-called "coupling agents" to improve the level of strength achieved throughout the reinforcement. In such cases, the use of a coupling agent may not be sufficient. Poly(p-phenylene terephthalamide) fibers have wide use as reinforcing materials in composite structures. According to the present invention, the introduction of certain monomer units in specific proportions into the polymer chain can reduce or eliminate the need for coupling agents in special applications. [0003]

[Summary of the present invention] The present invention essentially comprises the following repeating unit: [0004]

[0005] In the above formula, X is 1,4-phenylene,
and 2 is about 2 to 15 mole percent, in the indicated molar ratios, and fibers and films thereof. Also included are methods of manufacturing fibers. [0006]

The detailed description of the invention includes as its purpose the incorporation of small amounts of carboxyl groups along the aromatic polyamide chain in a manner that does not interfere with amide linkages. Carboxyl groups are known to enhance adhesion to rubbers, epoxides, etc. It has been found that fibers made from certain aromatic polyamides having a limited number of carboxyl groups on the mirror do not suffer from a significant decrease in tensile strength. The carboxyl group is paraphenylenediamine and 4,4”-diaminodiphenic acid (diaminodiphenic acid).
cid) by polymerizing the mixture with terephthaloyl chloride. Diphenic acid must be used as the dihydrochloride salt, as shown in co-pending application no. (QP-4365). [00071 The novel copolymers of the present invention are fiber-forming molecular weight polymers, have an inherent viscosity of at least 3.5 as measured as described below, and have essentially the following: Repeating unit: [0008] [0009] In the above formula, X is 1,4-phenylene,
and 2 is about 2 to 15 mol%, preferably 2 to 10
% by mole. The copolymer can be made into a spinning dope by dissolving it in concentrated sulfuric acid. The spinning dope should preferably contain at least 15% by weight of copolymer. The dope is spun through an inert fluid layer, preferably air, into a coagulation bath, such as water. The manufacturing method of the spinning dope and the spinning method are poly(p-)
Blaze (Bla) related to terephthalamide)
The method is similar to that used in U.S. Pat. [00101 Test method Inherent viscosity, 1. V is the following formula % formula %]

[0012] where RV is the relative viscosity and C is the concentration of the polymer in grams of polymer per deciliter of solvent. (Therefore, the units of inherent viscosity are dl/g.) Relative viscosity is measured by dividing the flow time of a dilute solution in a capillary viscometer by the flow time of pure solvent. The flow time is 30
Measured in °C. The solvent used is 100% H2SO4
It is. [0013] Measurement of tensile strength is ASTM D2101-8
The test was carried out on a single filament according to the test method given in 2. The filament was conditioned at 21°C (70°F) and 65% relative humidity and was heated at 10%/min using a flat lamp with a rubberized surface and a gauge length of 2.5 cm (1 inch). Elongation speed (low elongation,
The filaments were tested in a conventional tensile tester at 0.08%). T is the strength at break in gpd, M is the initial modulus in gpd and E is the elongation at break in %. [0014] The following examples are illustrative of the invention and are not intended to limit the invention. [0015]

[Example 1] Squirrel cage stirrer, thermometer, dry nitrogen purge,
Anhydrous N-methylpyrrolidone (407 ml; 420
g)/p-phenylenediamine (21,03 g; dissolved in anhydrous CaC12 (31,57 g; 0.287 mol)
:0.0103 mol) suspended in a solution of 4.4゛
-Diaminodiphenic acid dihydrochloride (3,54g; 0.0
A slurry of 103 mol) was treated with anhydrous diethylaniline (3,054 g; 0.0205 mol) at room temperature. Terephthaloid chloride (41.62 g; 0.205 mol) was added quantitatively to the resulting solution at 10°C. The initially clear solution turned into a crumbly gel or crumb-like form in a very short time. After leaving it at room temperature for 2 hours,
This is treated with excess cold water in a compounder to precipitate the polymer, which is filtered, washed with cold water, then treated in boiling water with stirring for 15 minutes to remove residual solvent, and refiltered. and dried at 100°C for 15 hours. 100%H2SO
1 out of 4. V was 4.08. Thermogravimetric analysis indicated retention of several percent residual solvent up to about 180°C. (0016) A 20% (wt/wt) solution of the polymer at 168 °C was passed through a single-hole spinneret with holes of 0.13 mm (0,005 in) in pore size and 0°38 mm (0,015 in) in length. , 6.35mm (0,25
The sample was extruded into a water coagulation bath at 0° C. through a gap of 1 inch). at 256 m/min and a spinning-drawing factor (S,
The fiber was wound up with S, F, ). Thoroughly washed and air-dried fibers have T/E/Mi/dpf=17.
It had 3gpd/4.2%/634gpd/1.5 denier. Wide-angle X-ray diffraction showed that these as-spun fibers were essentially amorphous. T/E/Mi is 20 by tubing the undried fibers under tension for 15 seconds in a nitrogen atmosphere at 200°C.
．． Changed on 3/2/8/840. By passing it over a hot plate under tension at 500°C, T/E/Mi is 18.6/
3.2/700 (best breaking, 21.2/3.9/6
80). [0017] [Example 2] A copolymer having an inherent viscosity of 4.68 was prepared in the same manner as in Example 1, except that the concentration of 4,4''-diaminodiphenic acid dihydrochloride was increased to 6 mol%. Similarly, fibers were spun from a sulfuric acid solution at 60°C,
The fibers were wound with a winding speed of 221 m/min and a spin-drawing factor of 8.1x. The as-spun air-dried fiber is T
/E/M i/dp f=15.1/4.31578/
It had a value of 1.8. The fibers were amorphous. 200
The undried fibers heat dried under tension at °C/15 seconds had T/E/Mi = 20.0/2.5/790. Air-dried fibers heat-dried under tension at 450°C have T/E/Mi = 18.1/4.0/64
7 (best at break, 20.6/4.5/667). [0018] [Example 3] Example 1 except that the concentration of 4,4'-diaminodiphenic acid dihydrochloride was increased to 12.5 mol%.
A copolymer having an inherent viscosity of 4.53 was prepared in a similar manner. Similarly, fibers were spun from the dope solution at 79°C, with a winding speed of 86 m/min and S, S,
The fiber was wound at F=2.9X. Air-dried fibers are T/E
/M i / d p f=10.315.1/404
/11.2 - The fibers were amorphous. 20
Undried fibers heated under tension at 0°C for 15 seconds are T/
It had E/M=11.0/2.2/600. Air-dried fibers passed under tension over a hot plate at 400-500°C showed no change in stress strain behavior or properties, nor did they exhibit any development of crystallinity or improved orientation. The stress stress curve exhibited a distinct inflection point, or yield point, beyond which the modulus decreased by more than 50%. [00191 The main features and aspects of the present invention are as follows. [002011, essentially the repeating unit [002
11 [00221] A fiber-forming molecular weight aromatic polyamide comprising in the indicated molar ratios, where X is 1,4-phenylene and 2 is about 2 to 15 mol%. . [0023] 2. 2. The polymer of claim 1, wherein z is about 2 to 10 mol%. [0024] 3. A spinning dope of the polymer described in 1 above and concentrated sulfuric acid is prepared at a concentration of at least 15% by weight, it is spun into a coagulation bath through an inert fluid layer, and the coagulated fibers are removed from the bath. A method for producing high-strength fiber. [0025] 4° High-strength fiber formed by the method described in 3 above.

Claims (3)

[Claims] [Claim 1] Essentially the following repeating unit: [Formula 1] ▲ Numerical formula, chemical formula, table, etc. ▼ In the formula, X is 1,4-phenylene, and z is about 2
A fiber-forming molecular weight aromatic polyamide comprising from 15 mole % to 15 mole % in the indicated molar ratios. 2. A spinning dope of the polymer of claim 1 and concentrated sulfuric acid is prepared in a concentration of at least 15% by weight, which is spun into a coagulation bath through a layer of inert fluid, and the coagulated fibers are removed from the bath. A method for producing high-strength fibers. 3. A high strength fiber formed by the method of claim 2.