KR101736720B1 - Poly(p-phenylene benzobisoxazole) copolymer having naphthalene, fiber compising the copolymer, and method for preparing the same - Google Patents

Abstract

The present invention relates to a polyparaphenylene benzobisoxazole copolymer improved in ultraviolet ray deterioration characteristics by the introduction of a naphthalene group, a fiber containing the copolymer, and a process for producing the same.

Description

TECHNICAL FIELD [0001] The present invention relates to a polyparaphenylene benzobisoxazole copolymer to which a naphthalene group is introduced, a fiber comprising the copolymer, and a method for producing the same. BACKGROUND ART [0002] }

The present invention relates to a polyparaphenylene benzobisoxazole copolymer improved in ultraviolet ray deterioration characteristics by the introduction of a naphthalene group, a fiber containing the copolymer, and a process for producing the same.

With the development of industries such as aerospace, automobiles, and ships, there is growing interest in high-performance fibers that are flexible and have high strength and high heat resistance in the field of textile materials. Among them, poly (p-phenylene benzobisoxazole) (PBO) fiber, which was firstly marketed by Toyobo in Japan under the trade name Zylon, is known to exhibit the highest tensile strength and elastic modulus among all commercialized synthetic fibers. PBO fiber is a typical heterocyclic aromatic polymer. Its strength is about twice that of para-aramid fibers. It has a modulus of elasticity similar to that of carbon fiber, a high decomposition temperature of about 650 ° C, and a flame retardancy of LOI of 65 In addition to having it, it also combines the characteristics of light and flexible fibers and is called the next generation super fiber.

These PBO fibers have great potential as reinforcing fibers for high performance composites in aerospace, military and industrial applications. However, in spite of its excellent strength, heat resistance and chemical resistance, the PBO fiber has a disadvantage in that the compressive strength is very low compared to the tensile strength. Further, the PBO fiber has a disadvantage in that it can not be used in the competitive aramid fiber, ultra high molecular weight polyethylene fiber or polyarylate fiber The fatal disadvantage of having a lower UV stability than the conventional one can impose limitations on the application field. There have been many researches on the surface treatment which improves the wettability with the resin in the composite material by increasing the surface energy of the PBO fiber. However, the mechanism of the degradation of the mechanical properties of the PBO fiber under UV irradiation and the UV There have been few developments in surface treatment technology to improve resistance. Zylon fiber, which has a strength of about 33 g / d before UV exposure, has a strength of about 15 g / d lower than that of industrial para-aramid fibers when exposed to UV for about 24 hours, by about 55% Research has also been reported on improving the UV resistance through hydroxyl-containing dihydroxy poly (p-phenylene benzobisoxazole) copolymers.

In Korean Patent Application No. 10-2007-0140499, as a patent for increasing the UV resistance to PBO fibers and other synthetic fibers, benzotriazole-based ultraviolet absorbers, phenolic and / or phosphite-based oxidative stabilizers and hindered amine light stabilizers There is proposed a melt spinning method of polyethylene terephthalate in which the light resistance of the polyethylene terephthalate is good while the light resistance against ultraviolet light is good and the strength is hardly lowered by mixing the polyethylene terephthalate base resin with the polyethylene terephthalate base resin in a predetermined amount, The method of PBO fiber, which is the object of the invention, can not be proposed.

The present invention relates to a process for producing polyparaphenylene benzobisoxazole, which comprises copolymerizing 2,6-naphthalene dicarboxylic acid (NDCA) having a naphthalene structure with a co-polymerization method to polymerize polyparaphenylene benzobisoxazole Sol-copolymer and a process for producing the same.

It is another object of the present invention to provide a fiber including the above-mentioned copolymer and having a greatly improved ultraviolet resistance, and a method for producing the same.

The invention 4,6-dia Minori SOCIETE play dihydrochloride (DAR) monomer and terephthalic acid (TPA) and 2,6-naphthalenedicarboxylic acid (NDCA) poly monomers include phosphorus pentoxide (P ₂ O ₅₎ A dehydrochlorination step of dissolving in a phosphoric acid (PPA) solvent to remove hydrogen chloride; A polymerization step of forming polyparaphenylenebenzobisoxazole (PBO) -NDCA precursor by polymerization through dechlorination of the monomers; And a cyclization step of forming a PBO-NDCA copolymer by a cyclization reaction of the PBO-NDCA precursor. The present invention also provides a method for producing a polyparaphenylene benzobisoxazole copolymer to which a naphthalene group is introduced.

Here, the 2,6-naphthalene dicarboxylic acid is preferably 1 to 20% by weight based on the total weight of the polyparaphenylenebenzobisoxazole copolymer into which the naphthalene group is introduced.

The reaction temperature in the dehydrochlorination, polymerization and cyclization steps is in the range of 50 to 250 ° C, and the concentration of phosphorus pentoxide in the polyphosphoric acid solvent is preferably 60 to 95%.

The present invention also provides a polyparaphenylene benzobisoxazole copolymer having a naphthalene group introduced by the above process and represented by the following formula (1).

[Chemical Formula 1]

The present invention also provides a fiber comprising the polyparaphenylene benzobisoxazole copolymer to which the naphthalene group is introduced, and a method for producing the same.

The polyparaphenylene benzobisoxazole copolymer according to the present invention can be obtained by copolymerizing 2,6-naphthalene dicarboxylic acid (NDCA) having a naphthalene structure with polyparaphenylene benzobisoxazole by simultaneous polymerization Whereby a naphthalene group is introduced.

By using the polyparaphenylene benzobisoxazole copolymer having such a naphthalene group introduced therein, it is possible to compensate for the low UV stability, which is a disadvantage of the PBO fiber, and to reduce the decrease in the strength by UV.

1 is a graph showing the polymerization process of the copolymer according to Example 1 showing the temperature and the PPA concentration over time.
Figure 2 shows a dry-wet emitter for making fibers according to an embodiment.
3 shows an ultraviolet irradiation apparatus for measuring ultraviolet resistance of fibers according to Examples and Comparative Examples.
FIG. 4 is a graph showing tensile properties of the fibers according to Comparative Example 1 according to ultraviolet irradiation time. FIG.
5 is a graph showing the strength retention ratios of the fibers according to Examples 1 to 3 and Comparative Example 1 according to ultraviolet irradiation time.
6 is a graph showing the diameter reduction rate of the fibers according to Examples 1 to 3 and Comparative Example 1 according to ultraviolet irradiation time.
7 shows the surface roughness of the fiber according to Example 3 and Comparative Example 1 before and after irradiation with ultraviolet rays.

Hereinafter, the present invention will be described in detail.

1. Copolymers and methods for their preparation

The present invention provides a polyparaphenylene benzobisoxazole (PBO) copolymer having a naphthalene group introduced therein.

 [Chemical Formula 1]

The present invention can produce a fiber using the copolymer of the formula (1).

The copolymer represented by Formula 1 according to the present invention can be prepared by various methods.

According to an embodiment of the present invention, as shown in the following Reaction Scheme 1, a tetrafluoroethylene (TPA) monomer and a 2,6-naphthalene dicarboxylic acid (NDCA) A dehydrochlorination step of dissolving in a polyphosphoric acid (PPA) solvent containing phosphorus (P ₂ O ₅ ) to remove hydrogen chloride; A polymerization step of forming a polyparaphenylene benzobisoxazole (PBO) -NDCA precursor by polymerization of the monomers; And a cyclization step of forming a PBO-NDCA copolymer by a cyclization reaction of the PBO-NDCA precursor.

[Reaction Scheme 1]

First, 4,6-dia Minori SOCIETE play dihydrochloride (DAR) of phosphorus pentoxide and the monomers terephthalic acid (TPA) and 2,6-naphthalenedicarboxylic acid (NDCA) monomer (P ₂ O ₅₎ concentration of 70 to 85 % In a polyphosphoric acid (PPA) polymerization solvent, and the dehydrochlorination reaction proceeds while stirring in a nitrogen atmosphere.

At this time, SnCl ₂ is preferably added as an antioxidant.

The stirring temperature and time are not particularly limited, but the temperature is preferably in the range of 50 to 100 ° C, and the stirring time is preferably 2 to 8 hours.

After the dehydrochlorination reaction is completed, phosphorus pentoxide is further added into the reaction mixture to raise the solubility of the polymer, and the temperature is raised to polymerize with stirring in a nitrogen atmosphere. At this time, the concentration of phosphorus pentoxide in the polyphosphoric acid solvent is preferably 85 to 95%, but is not limited thereto. When the concentration of phosphorus pentoxide is less than 80%, the polymerization reaction does not progress efficiently, and when the concentration of phosphorus pentoxide exceeds 95%, the dissolution of the monomers is not easy and the reaction is difficult to proceed.

The polymerization temperature and time are not particularly limited, but the temperature is preferably in the range of 100 to 170 ° C, and the polymerization time is preferably 5 to 10 hours.

If the reaction temperature is less than 100 ° C, the solubility of the polymer is low and the reactivity is poor. It is difficult to raise the degree of polymerization efficiently because polymerization and cyclization occur simultaneously at 170 ° C.

Finally, the copolymer of the present invention can be prepared by heating at a high temperature in a nitrogen atmosphere to cause a cyclization reaction. The heating temperature and time for the cyclization reaction are not particularly limited, but the temperature is preferably in the range of 170 to 200 ° C, and the time is preferably 3 to 15 hours.

In the above Reaction Scheme 1, the 2,6-naphthalene dicarboxylic acid is preferably 1 to 20% by weight based on the total weight of the polyparaphenylenebenzobisoxazole copolymer into which the naphthalene group is introduced, but is not limited thereto.

2. Fibers and methods for their manufacture

The present invention provides a fiber comprising the copolymer (1). The copolymer of the present invention is produced by co-polymerization of 2,6-naphthalene dicarboxylic acid having a naphthalene structure, the disadvantage that the strength of PBO is greatly deteriorated under ultraviolet (UV). The present invention can produce fibers using a copolymer having such properties.

Since the fiber of the present invention contains the copolymer represented by the above formula (1), ultraviolet resistance is greatly improved.

Such fibers of the present invention can be prepared by dry-jet wet spinning. Specifically, first, the copolymer obtained by the above-mentioned formula (1) is used as a radiation dope. Since it is difficult to dissolve the solution-polymerized copolymer after the recovery, the polymer should be polymerized in the range of 10 to 15% by weight in terms of the concentration of the polymer in the PPA so that the concentration of the polymer is suitable for the fiber spinning. Thereafter, the spinning dope is ejected through a spinneret in a liquid crystal state by a dry-wet spinning method, and then the spinning dope is put into a coagulating bath, solidified, and then washed and wound. At this time, the spinning temperature for forming the liquid crystal is preferably 100 to 150 ° C, and the air gap is preferably 1 to 10 cm.

The nozzle diameter of the spinneret is not particularly limited, but a spinneret having a diameter of 0.2 mm is used in the present invention.

The coagulating solution of the coagulating bath is not particularly limited, but a 1 to 20% aqueous solution of phosphoric acid is preferable in terms of concentration weight ratio

A fiber comprising the PBO copolymer (formula (I)) prepared by the above method and having a naphthalene group introduced therein may have enhanced ultraviolet resistance as compared to PBO fibers.

Hereinafter, the present invention will be described in detail with reference to examples. However, these examples are for illustrating the present invention specifically, and the scope of the present invention is not limited to these examples.

[Example 1]

<Step 1> Synthesis of Copolymer

PPA (P ₂ O ₅ 80%) was used as the solvent for the synthesis of PBO-NDCA, and the concentration of PBO-NDCA in the whole reaction solution was constantly adjusted to 14.0 wt%. All reaction steps (dehydrochlorination step, polymerization step, cyclization step) for preparing the PBO-NDCA copolymer were carried out in a nitrogen stream.

In the first dehydrochlorination step, 40.0 mmol of DAR, 41.7 mmol of TPA, 1.3 mmol of NDCA and 2.4% by weight of antioxidant SnCl ₂ were added to a three-neck round flask containing solvent PPA (P2O5 80%), C for 8 hours to remove hydrogen chloride.

In the second polymerization step, P ₂ O ₅ was added to the reaction flask to increase the P2O5 concentration in the solvent PPA to 87%, and then the reaction was carried out at 110 ° C. for 7 hours and 150 ° C. for 6 hours to obtain PBO and PBO- . The reason why the P ₂ O ₅ concentration in the PPA solvent is increased to 87% by adding P ₂ O ₅ during the polymerization step is because the monomers having a high solubility for P ₂ O ₅ are mainly present in the flask at the initial stage of the polymerization, Through which polymers with low solubility to P ₂ O ₅ are synthesized. The concentration of P ₂ O _{5 in the} PPA solvent is lowered to about 84% by weight because water is produced in the polymerization reaction and the cyclization reaction.

In the final cyclization step, PBO and PBO-NDCA precursors were thermally cyclized at 190 ° C for 12 hours to finally produce PBO and PBO-NDCA. Figure 1 is a graph showing the temperature and PPA concentration over time during polymerization.

0.5 g of the obtained PBO and PBO-NDCA polymer were dissolved in 100 ml of methanesulfonic acid (MSA), and the intrinsic viscosity (IV) was measured at 30 ° C. using a Ubbelohde viscometer. The molecular weight (M _w ) Are shown in Table 1 below.

[?] = kM _w ^a (k = 2.77 x 10 ^-7 , a = 1.8)

<Step 2> Production of fiber

The PBO and PBO-NDCA copolymer solutions synthesized in the above <Step 1> were made into fibers using a dry-wet spinning machine as shown in FIG. The spinning rate was 0.9 m / min through a spinneret with a diameter of 0.2 mm at a spinning temperature of 140 ° C and an air gap of 10 cm. The radiated fibers undergo a two-step coagulation process. The primary coagulation bath consisted of 5 wt% aqueous phosphoric acid solution, and the secondary coagulation bath and wash bath consisted of distilled water. The winding speed was set at 25.9 m / min. The fabricated PBO fibers and PBO-NDCA fibers were dried in a vacuum oven at 25 ° C for 24 hours.

[Examples 2 and 3]

Copolymers and fibers were prepared by the same procedure as in Example 1 except that the contents of TPA and NDCA were adjusted as shown in Table 1 below.

[Comparative Example 1]

Copolymers and fibers were prepared by the same procedure as in Example 1 except that the contents of TPA and NDCA were adjusted as shown in Table 1 below.

DAR
(mmol) TPA
(mmol) NDCA
(mmol) SnCl ₂
(wt%) Polymerization solvent PPA concentration (P ₂ O ₅ %) PBO concentration of polymer
(wt%) Intrinsic viscosity (dl / g) Molecular Weight
(g / mol) Comparative Example 1 40.0 43.0 0.0 2.4 80.0 -> 87.0 14.0 9.2 15080 Example 1 41.7 1.3 9.6 15440 Example 2 40.4 2.6 9.7 15530 Example 3 39.1 3.9 9.2 15080

[Experimental Example 1] Measurement of ultraviolet resistance

In order to measure the ultraviolet resistance of the fibers prepared in Examples 1 to 3 and Comparative Example 1, ultraviolet rays were irradiated to the fibers using a self-made ultraviolet irradiation apparatus as shown in Fig. 3 and an ultraviolet lamp as shown in Table 2 below For 8 to 24 hours.

4 is a graph showing tensile strength and elongation when pure PBO fibers are irradiated with ultraviolet rays. It can be seen that as the ultraviolet irradiation time is increased, the intensity and elongation decrease sharply. It is known that the reason that the intensity of PBO fiber due to ultraviolet rays is lowered is that the heterocycle breaks down due to ultraviolet rays as shown in the following reaction formula (2).

[Reaction Scheme 2]

Fig. 5 shows the results of measurement of the tensile strength retention ratio after ultraviolet irradiation of the fibers prepared in Examples 1 to 3 and Comparative Example 1, respectively. As the NDCA is introduced, the decrease in strength due to ultraviolet irradiation is alleviated, and it is understood that the ultraviolet resistance is improved.

In addition, the PBO fiber exhibits a phenomenon in which the diameter is decreased remarkably as the intensity is reduced by ultraviolet irradiation. Table 3 and Fig. 6 show the change in diameter and the reduction rate of diameters of PBO and PBO-NDCA fibers according to ultraviolet irradiation, respectively. It can be seen that the reduction rate of the diameter is lowered as the reduction rate of strength is lowered according to the NDCA content.

Ultraviolet irradiation time (h) Fiber diameter before and after ultraviolet irradiation (탆) Comparative Example 1 Example 1 Example 2 Example 3 0 15.3 16.0 15.1 13.2 8 13.2 14.3 13.8 12.3 16 12.4 13.7 13.3 12.0

Fig. 7 shows the results of comparing the surface roughness of the fibers prepared in Comparative Examples 1 and 3, respectively, before and after irradiation with ultraviolet rays, using an atomic force microscope (AFM). As can be seen from Fig. 7, it can be seen that the surface of NDCA-containing fiber (Example 3) after ultraviolet irradiation is much smoother.

Claims (4)

(TPA) and 2,6-naphthalene dicarboxylic acid (NDCA) monomers are reacted with polyphosphoric acid (PPA) containing phosphorus pentoxide (P ₂ O ₅ ) and a 4,4'-diaminorisosolic dihydrochloride (DAR) ) A dehydrochlorination step of dissolving in a solvent to remove hydrogen chloride;
A polymerization step of forming polyparaphenylenebenzobisoxazole (PBO) -NDCA precursor by polymerization through dechlorination of the monomers;
A cyclization step of forming a PBO-NDCA copolymer by a cyclization reaction of a PBO-NDCA precursor; And
Preparing a solution containing the PBO-NDCA copolymer by using a dry-wet emitter,
The 2,6-naphthalene dicarboxylic acid is 1 to 20% by weight based on the total weight of the naphthalene-introduced PBO-NDCA copolymer,
The PBO-NDCA copolymer is represented by the following formula (1)
Wherein the fiber has a fiber diameter reduction ratio of 9.1 to 14.4% before and after irradiation of ultraviolet rays at a wavelength of 300 to 500 nm for 16 hours, and a strength retention ratio of 55% or more.
[Chemical Formula 1]

delete delete delete

Images