JPS58203116A - Flame-retardant poly (p-phenylene terephthalamide) fiber - Google Patents

Abstract

PURPOSE:The titled fibers, consisting of poly (p-phenylene terephthalamide), having contents of phosphorus atoms and sulfur atoms in the fibers within a specific range and improved mechanical properties thereof and further improved flame retardancy. CONSTITUTION:Flame-retardant poly (p-phenylene terephthalamide) fibers, consisting substantially of the poly (p-phenylene terephthalamide), having >=1.40g/ml density and >=0.2 birefringence value and >=1X10<-2> ratio (Wp/Ws) between the weight content (wp) of the phosphorus atoms and the weight content (Ws) of the sulfur atoms. An optically anisotropic dope is prepared from preferably 90- 100wt% sulfuric acid, 0.1-0.6mol, based on one mole water contained in the above-mentioned sulfuric acid, phosphorus pentoxide and the poly (p-phenylene terephthalamide), and the resultant dope is then spun to give the aimed fibers.

Description

DETAILED DESCRIPTION OF THE INVENTION This madder is made of poly(p-phenylene alephthalamide) fi&[clX, which has excellent mechanical properties and is flame retardant.

Aromatic polyamide fibers have increased in density in recent years due to their heat resistance and attractive appearance, but poly(p-
On the other hand, the solubility of para-isolated aromatic polyamides such as phenylene terephthalamytonyl is poor, and the only good solvents known are concentrated sulfuric acid and other similar compounds.

For example, in Publication No. 5!5-14170, at least 98% diluted sulfuric acid, trisulfuric acid, fluorine sulfuric acid, and mixtures of these acids are used as bath media, and aromatic aromas that are similar to these acids are used as bath media. The raw material dope is made entirely from the polyamide group, and the fiber or film with the material properties is obtained from the polyamide. The flame retardance of the film is as follows:
There is no mention of this in the official bulletin. Since the polyamide fiber or film described in the watch publication is self-heated at 711 flames (4 tons), it seems that flame retardancy was generally not considered.

In the process of conducting research on fiber or film OIJ and combustion in Japanese Patent Publication No. 55-14170, Motomoto Akishino et al. unexpectedly found that dope contained a gender-specific phosphorus compound in a gender-specific manner. It was discovered that wet-forming the phosphorus yarn compound improved its effectiveness. It has also been found that a useful optically anisotropic dope can be formed even when using less than 98% by weight of sulfuric acid, which has been considered undesirable. In the case of poly(p-phenylene terephthalamide) fibers, the parameters reflecting the physical microstructure have a special range, and the content of phosphorus atoms in the fiber has a special range with respect to the content of iodine atoms. The present invention was achieved based on the discovery that the presence of fibers is closely related to the excellent mechanical properties and flame retardancy of the fibers.

That is, the present invention is made essentially of poly(p-phenylene terephthalamide), has a density of 1,40y7cc or more and a birefringence value of 0.2 or more, and has a weight content (Wp) of phosphorus atoms and a 9Jjli, a poly(p-phenylene terephthalamide) fiber having a ratio of in content (Ws) Wp/Ws of I x 10'' or more.

The fiber of the present invention is overwhelmingly composed of a polymer consisting essentially of poly(p-phenylene terephthalamide). Here, the meaning of the phrase "substantially" is that the repeating level other than p-phenylene terephthalamide (e.g. m-phenylene terephthalamide, p-phenylene terephthalamide,
The scope of the present invention also includes M@ bodies containing about 5 mol% t-c' gold (phenylene inophthalamide, p-phenylene terephthalamide whose nucleus is substituted with a halogen group, an alkyl group, a nitro group, a sulfone group, etc.). should be construed as included in

Poly(p-phenylene terephthalamide) (hereinafter referred to as P
The fiber of the present invention has an intrinsic viscosity (ηin) of about 3.0 or more as measured by the method described below.
h) is preferable in order to improve the mechanical properties of the fiber.

The fibers of the present invention may contain conventional additives, such as dyes, deglossers, violet light stabilizers, light stabilizers, adhesive oils, etc., but it is important that IPI ! , the ratio Wp/Ws of the it content (Wp) of phosphorus atoms and the weight content (WS) of iota atoms contained in the fiber is I x 10
It must be -2 or more.

This is because satisfying such conditions is one of the necessary conditions for achieving flame retardation of fibers. Wp/
Ws is preferably 3×101 or more. PPTA fibers satisfying such a Wp/Ws value are conveniently manufactured by the manufacturing method described below. Note that Wp and Ws can be measured by a normal elemental analysis method.

In order for the fcPPTA fiber to have excellent mechanical properties and excellent flame retardancy, it must have a density of 1.409/C1 or more and a birefringence value of 0.2 or more.

Here, the density was measured using a density gradient tube method using ethanol and carbon tetrachloride at 25°C.
The birefringence value is measured using NaD rays as a light source, and can be measured, for example, by the method of Yabuki et al. [Textbook Journal, Vol. 31, No. 11, p. T-524 (1975)].

It can be interpreted that fibers with such structural characteristics do not contain excessive voids and have crystallinity and polymer chain orientation above a certain level. In order to further strengthen the effects of the present invention, t'j
, 1,42 f /cc or more and a birefringence value of /''! or 0.3 or more.

A convenient method for fully loading the fibers of the present invention will be described below, but the method is not limited to this method.

The fibers of the present invention are made of 4JIIc acid having a degree of 90% by weight or more and 100% by weight or more and not more than 100% by weight, and 0.1 mol or more and 0.6 mol or less per 17 liters of water contained in the sulfuric acid. optically anisotropically doped from diline pentoxide and PPTA, the dope is spun into a non-coagulating fluid, and then the spun fiber stream is solidified in a coagulating medium, washed with water and dried. obtained by

The solvent used to obtain the fibers of the present invention should be as small as 90 violets or more and less than 100 violets, preferably Fi94
In this way, it is essentially made up of a mixture of sulfuric acid with a concentration of less than 99 times the concentration (therefore, the remainder is water) and diphosphorous pentoxide. The triphosphorus pentoxide-containing violet used as a component of the solvent of the present invention is the key to the water contained in the sulfuric acid, that is,
According to the number of moles of water, the molar ratio is H2O: Pr
os = ''' (here, A is 0.1≦A≦0.6)
selected within the range. The reason why A is selected within this range is as follows. That is, in the case of A<o,1, the flame resistance of the obtained fiber does not improve after wet molding;
In the case of CA>0.6, when the sulfuric acid is mixed with p, o, the decomposition reaction of the #i acid is too slow, or the PPTA tends to deteriorate and the intrinsic viscosity decreases. Undesirable for some reason. Human value is preferably 0
．． 2 to 0.5, more preferably 0.30 to 0.
It is 65.

The reason why 90% by weight or more and less than 100% by weight of sulfuric acid is used is as follows. 90 wt% sulfuric acid no longer dissolves PPTA sufficiently;
For sulfuric acid of more than % by weight, the P to be added is 0. The initial goal of improving flame resistance will not be achieved if the number of fires is reduced. The sulfuric acid preferably has an Fi of 94 to 99 by weight, and in this case, fibers with good mechanical properties and sufficient flammability, which are the effects of the present invention, can be provided.

In the above method, it is important to use an optically anisotropic dope. Here, whether or not the dope has optical anisotropy can be measured, for example, by the method described in Japanese Patent Publication No. 50-8474. It is thought that the fact that the dope has optical anisotropy corresponds to the fact that it forms a liquid crystal.

The reason for using optically anisotropic doping should be understood as follows. In other words, it cannot be considered that the fact that the dope has optical anisotropy itself is directly related to the excellent mechanical properties of the fiber; rather, it is the high polymer concentration in the dope that is important. It should be considered that the strong polymer properties are responsible for the optical anisotropy in the doped state and the excellent mechanical properties in the fibers. Therefore, optical anisotropy is important as an indicator of useful high polymer properties, so to speak.The range of polymers that exhibit optical anisotropy is:
Although it will vary slightly depending on the degree of polymerization (intrinsic viscosity) of PPTA, the temperature of the dope, the sulfuric acid concentration, and the exact amount and pressure of PtO%,
As will be explained in detail later, the amount is about 10 or more.

The polymer concentration of the dope may be as long as it forms an optically anisotropic dope. Specifically, the polymer concentration of the entire solution (sulfuric acid, P,
03 and PPTA), the appropriate amount is about 10 to 25 weight percent, preferably 14 to 20 weight percent.

In this method, P, 0. The timing of adding PPTA can be any time when dissolving PPT.
A method of adding p, o, after thoroughly dissolving it,
The P is added to sulfuric acid in advance. After dissolving the PPT
A method of adding A, etc. is used. When dissolving PPTA in the above solvent, hydrogen fluoride, hydrogen chloride, fluorosulfuric acid, chlorosulfuric acid, antimony trifluoride, antimony trifluoride, boron trifluoride, phosphorous trifluoride, etc. may be used as a dissolution aid. You can also use more than one of them.

The fibers of the present invention may be blended with well-known compounding agents such as antioxidants, heat stabilizers, ultraviolet absorbers, colorants, and erasing agents according to known formulations. Further, in order to further improve the flame retardancy of the fiber of the present invention, a conventional flame retardant may be added.

To manufacture the fiber, a technology similar to the conventional wet spinning method can be used.
After passing through an oriice and a non-coagulating medium such as air, extrusion into a coagulating medium and assimilation into fibers takes place in the coagulating medium. Water is preferably used as the coagulation tM negative, but methyl alcohol, ethylene glycol, glycerin, polyhydric alcohol such as impropatol, a mixture of water and alcohol, or sulfuric acid can also be used. Acids such as hydroxide, alkalis such as hydroxide, and various salts such as calcium chloride can be used.

The temperature of the dope or coagulation medium during this wet spinning is not particularly limited, but it is generally desirable to be in the range of 10 to 100°C. As the non-coagulable medium, a gas such as air or a natural gas or a dose-immiscible liquid such as a hydrocarbon liquid is used, and as the #l solid medium, those exemplified in m are used. The fibers wound at an appropriate spinning speed are treated with a cleaning solution such as water or a chemical solution, and then
It is dried with air at ~150°C for an appropriate period of time. Depending on the case, heat treatment at an appropriate temperature can also be performed.

The fiber of the present invention has a unique trace element content, high density, and birefringence value, and it is believed that these characteristics have excellent properties such as flammability, high strength, and high initial modulus. . Because of these characteristics, it has many industrial uses, such as reinforcing materials for rubber products such as tire cords, rubber belts, and hoses, or as fiber reinforcing materials for various fiber-reinforced plastics, or for industrial purposes such as ropes, plastic cloth, and various covers. It is useful in applications as clothing fibers such as fibers and sewing threads.

Hereinafter, the present invention will be explained in detail by giving examples and comparative examples thereto.

In addition, JIS, which is generally used as an indicator of flame retardancy,
-K.7201 was adopted and the ultimate oxygen index (LOI) was measured accordingly.

The intrinsic viscosity (yinh) was expressed by the following formula.

η1nh=tn (ηr)/C In the above formula, C is the concentration of the polymer solution (0.59 of polymer' or fiber in 100 mt of solvent), and ηr (relative viscosity)
ri, determined by dividing the flow time of the polymer solution, measured at 55° C. in a capillary viscometer tube, by the flow time of the pure solvent. In this case, the solvent is an incorrect value #! (95-981:%
) is used.

Example 1 and Comparative Example 1 After dissolving P, 0.142 f (1 mol) in 97.5 wt% H, So, 2700 F (containing water 5.75 mol), PPTA (+7 inh = 4.4 ) 595
1 was added and melted at 70 to 75°C to obtain a glossy optically anisotropic dope in about 1.5 hours. Solution viscosity e 270
0 voids (71°C). The whole was transferred to a spinning device kept at 75°C, and after vacuum degassing for about 2 hours, it was passed through 4 tubes with a built-in filter and filter using a gear pump.
The material was introduced into a spinneret with a φX50 hole, a 5 TuM air layer was passed through it, it was extruded vertically into water at 3° C., and a draft was applied and the product was wound onto a bobbin. - After washing by immersion in running water at night, it was dried at 100°C for 2 hours to obtain a yarn (q iah: 4.2). The results are shown in Table 1.

In Table 1, the fibers spun at a trough) of 1.80 are:
This fiber is outside the scope of the present invention in terms of birefringence value and is inferior in terms of strength and flame retardancy.

Table 1 Comparative Example 2 97.5 mid H, So, 2700? PPT to
Add A (+7inh-4,4) 593 f/,
It was melted at 70 to 75°C, and a shiny optically anisotropic dope was obtained in about 2 hours. Solution viscosity is 4720 boids (71℃)
Met. Table 2 shows the physical properties of the fiber (ηinh = 4.0) obtained using the same spinning device and spinning conditions as in Example 1.

Table 2 The fiber of this comparative example is outside the scope of the present invention in terms of Wp/Ws, and therefore has a relatively small LOI value.

Example 2 95.2% by weight H2804275Of (containing 7.35 moles of water), P, 0.341? (2,40
After dissolving PPTA (η1nh=5.5)
341? was added and melted at 70 to 75°C to obtain a shiny optically anisotropic dope in about 2 hours. Solution viscosity is 41
00 Boise (71'C). Table 4 shows the physical properties of the fiber (ηinh 25.3) obtained by wet spinning in the same manner as in Example 1.

Table 4 Spinning was performed using the optically anisotropic dope of Example 2.

At this time, the method and conditions were exactly the same as in Example 1, except that the coagulation bath temperature was 60°C.

The PPTA fiber obtained with a draft of 2.85 is 13.4
Strength of /d, elongation of 5.6, modulus of 285 /d, Wp% of 152-99 opIm Ws
, had a birefringence value of 1.58 f/CC (D density, 0.29), and a t, ohm of 5o. The density is outside the range of the present invention, and in this respect, compared to the fiber of Example 2, the strength and elongation and L
It is estimated that the OI value was low.

Example 3 95.04 violet%) I, 5o4273 ON (Contained water 10.61 mol) K, P, 0.502? (
3゜54%ru) after tmm PPTA (y7inh=4
．． 4) 655 t was added, heated at 75 to 80°C, and an optically anisotropic dope with a glossy finish was obtained in about 2.5 hours.

The solution viscosity is 5200 voices (71°C), fC. Wet spinning was carried out in the same manner as in Example 1 and □. The obtained fiber (ηi
Table 5 shows the physical properties of nh = 4.5).

Claims (1)

[Claims] Wxa is made of poly(p-phenylene terephthalamide) and has a value of 1.40? / has a weight of C or more and a plate refraction of 0.2 or more, and has a weight of phosphorus atom ""*(
Wp/'
poly(p-phenylene terephthalamide)'') km, wherein Ws is I x 10-'' or more.