JP2513816B2 - Surface treatment method for aromatic polyamide - Google Patents

Description

TECHNICAL FIELD The present invention relates to a surface treatment method for aromatic polyamide.
More specifically, the surface amide group of the aromatic polyamide is
-It relates to a surface treatment method for improving light resistance by acylation.

[Prior Art] Aromatic polyamide, as a linear polymer, has a rigid and highly oriented structure, and therefore exhibits high strength, high melting point, high elastic modulus, and excellent heat resistance and dimensional stability. It is processed into fibers, films, pulps, papers, etc., and is used as a heat-resistant industrial material, and is drawing attention.

However, aromatic polyamide has a drawback that it is likely to undergo discoloration (yellowing) or deterioration (decrease in strength characteristics) when irradiated with light, and thus it is used outdoors (exterior film,
In the field of clothing and the like), the deterioration of the surface is significant, which is a major limitation.

Therefore, a method of coating the surface of the aromatic polyamide in order to prevent deterioration by light is conceivable, but this method results in an increase in weight, the original high specific strength is not utilized, and the coating wears and falls off. There is also.

On the other hand, there is also a method of molding after kneading the light resistance stability, but the types of stabilizers are limited, and in the dispersed state, the effect against light coming from the surface is small, and the deterioration of physical properties is large. Not practical.

On the other hand, there are attempts to improve the light resistance by adding various substituents to the amide group on the amide surface. For example, an N-alkoxyalkyl group as disclosed in JP-A-60-252626 is used. A method of introducing the alkyl group and a method of introducing an alkyl group containing a hindered phenol group as disclosed in JP-A-63-92775 are known. Although these methods are effective to some extent, in order to add an alkyl group which is an electron-donating group to the amide bond, the amide bond itself is not strengthened, and the drawback that the amide bond is easily broken by light cannot be covered. The inventors also conducted a follow-up test, but yellowing occurred due to long-term irradiation, and satisfactory results were not obtained. Furthermore, the method of introducing hindered phenol was not practical because the N-substitution rate was also poor.

[Problems to be Solved by the Invention] When an aromatic polyamide is irradiated with light and the surface structure changes before and after the irradiation are examined, it is not only deteriorated by light, but also amide bonds are oxidized by oxygen in the air, I also found that it was cut. Therefore, in order to improve the light resistance, how to prevent the oxidation of the amide bond that occurs at the same time as the photodegradation is an important issue.

An object of the present invention is to provide an aromatic polyamide having improved light resistance, particularly an aromatic polyamide suitable for films and fibers.

[Means for Solving the Problems] As a result of intensive investigations by the present inventors based on the above problems,
It was found that the light resistance is improved by making the surface amide bond N-acylated and modifying it to an imide bond, which makes it difficult to oxidize, and improves the light resistance without lowering the mechanical strength, and has reached the present invention.

That is, the present invention is a surface treatment method for an aromatic polyamide, which comprises subjecting a surface amide group of the aromatic polyamide to N-acylation reaction treatment.

The reason why the aromatic polyamide obtained by the method of the present invention exhibits good light resistance is considered that the surface amide group is imide-modified, and the amide bond itself is changed to an imide bond that is less susceptible to photodegradation. To be

In the aromatic polyamide used in the present invention, at least 90 mol% or more of amide bonds are obtained from the aromatic cyclic diamine and the aromatic cyclic dicarboxylic acid component. Examples of its structure include polyparabenzamide, polyparaphenylene terephthalamide, poly 4,4′-diaminobenzanilide terephthalamide, polyparaphenylene-2,6-naphthalic amide, copolyparaphenylene / 4,4 ′ (3 ,
3'-Dimethylbiphenylene) -terephthalamide, copolyparaphenylene / 2,5-pyridylene-terephthalamide, polyorthophenylenephthalamide, polymetaphenylenephthalamide, polyparaphenylenephthalamide, polyorthophenyleneisophthalamide, polymetaphenylene Isophthalamide, polyparaphenylene isophthalamide, polyorthophenylene terephthalamide, polymetaphenylene terephthalamide, poly (4-
Methyl-metaphenylene) terephthalamide, poly (4
-Methylmetaphenylene) isophthalamide, poly-1,
5-naphthalenephthalamide, poly-4,4'-diphenylene-ortho-phthalamide, poly-4,4'-diphenyleneisophthalamide, poly-1,4-naphthalenephthalamide, poly-1,4-naphthaleneisophthalamide , Poly-1,5-naphthalene isophthalamide and the like and compounds in which a part of the benzene nucleus of these aromatic diamines is substituted with halogen, and further a part of the benzene nucleus of these aromatic diamines is piperazine, 2,5- Dimethylpiperazine, 2,5-
Aromatic polyamide containing an alicyclic amine represented by a compound substituted with diethylpiperazine, or an aromatic diamine is an ether group such as 3,3′-oxydiphenylenediamine or 3,4′-oxydiphenylenediamine, An alkyl group,
-S -, - SO ₂ -, Aromatic polyamides containing two phenyl groups linked by groups such as -NH-, or copolymers of the aromatic polyamides mentioned above, eg poly-3,3'-oxydiphenylene terephthalamide / polyparaphenylene terephthalamide copolymers. Examples thereof include polymers and poly-3,4'-oxydiphenylene terephthalamide / polyparaphenylene terephthalamide copolymers. Among them, polymetaphenylene isophthalamide is a commercially available and preferred aromatic polyamide since it is commercially available. More preferably, it is poly (4-methyl-metaphenylene) terephthalamide developed by the inventor, and the effect of improving light resistance is even higher.

The production method of these aromatic polyamides is not limited in carrying out the present invention, and for example, produced from a corresponding diamine and diacid chloride by a low temperature solution polymerization method known in JP-B-35-14399. Or from the corresponding diisocyanates and carboxylic acids.
-190517, JP-A 61-204218, etc.

In the method of the present invention, the aromatic polyamide is N
-Requires acylation, the reaction treatment being carried out in the form of powders or moldings of aromatic polyamides, for example films, fibers, papers, plates.

The N-acylation reaction treatment can be performed by a known method using an acylating agent.

More specifically, for example, sodium halide is added to dimethyl sulfoxide (hereinafter abbreviated as DMSO), and
Room temperature to 70 ° C., after mixing with the aromatic polyamide soaked in dioxane, into a solution dissolved at ˜80 ° C. or in a solution of triethylamine in N-methylpyrrolidone (hereinafter abbreviated as NMP). Preferably, after stirring at 45 to 55 ° C. for 1 hour or more, an acylating agent is added and N-acylation reaction treatment is carried out.

In the method of the present invention, known acylating agents can be used, but acyl chloride is preferably used. The number of carbon atoms in the acyl group is preferably 6 or less, and the use of acetyl chloride is most preferable.

This reaction treatment may be carried out by only partially acylating the amide group, and the N-acylation rate of the surface amide group is usually 20 to 90%.
The degree is suitable. The conversion rate of the surface acylation can be determined by quantifying the surface acyl group of the obtained polyamide by surface reflection infrared absorption spectrum (ATR).

[Examples] Hereinafter, the method of the present invention will be described with reference to Examples, but the present invention is not limited thereto.

Example 1 <Production of poly (4-methyl-metaphenylene) terephthalamide> N, N′-dimethylethylene urea (hereinafter referred to as “N, N′-dimethylethyleneurea” was placed in a reactor equipped with a stirrer, a thermometer, a condenser, a dropping funnel, and a nitrogen introducing tube. DMI) 800 g, terephthalic acid 33.
After charging 2 g (0.20 mol) in a nitrogen atmosphere, the mixture was heated to 200 ° C. with nitrogen gas while stirring. Further, heating was continued for 1 hour while continuing nitrogen bubbling to distill 80 g of DMI.
The water content of the solution in the reactor was 20 ppm or less.

Then potassium fluoride powder dried at 150 ℃ for 15 hours
0.12 g (1.0 mol% with respect to terephthalic acid) was added in a nitrogen atmosphere, and the temperature was raised to 200 ° C. with stirring. D in the reactor
While maintaining the temperature at 200 ° C. while passing nitrogen through the MI solution, 34.8 g (0.20 mol) of tolylene-2,4-diisocyanate was continuously added dropwise by a dropping funnel over 1.5 hours under a nitrogen atmosphere. After the dropping was completed, the temperature was maintained at 200 ° C. for 30 minutes and then cooled to room temperature to obtain a pale yellow polyamide polymer solution.

This polymerization solution was subjected to DMI at 50 ° C using a usual wet spinning device.
Extruded into aqueous solution. Spinning was possible without causing yarn breakage, and a yarn of 2 denier was obtained after dry drawing. The strength was 6.5 g / denier per yarn.

<N-Acetylation of poly (4-methyl-metaphenylene) terephthalamide> DMSO (150 ml) and sodium hydride (0.63 g) were placed in a 300 ml reactor equipped with a stirrer, a thermometer, and a nitrogen inlet tube, and the mixture was stirred under a rapid nitrogen flow to 70 After heating at 0 ° C for 1 hour to completely dissolve it, the mixture was cooled to 40 ° C. To this solution was added a mixture of 4 g of poly (4-methyl-metaphenylene) terephthalamide fiber obtained by the above production method in 100 ml of dioxane, and the mixture was stirred at 40 ° C. for 20 minutes, and then acetyl chloride 1.
24 g was added, and the mixture was reacted by stirring at 50 ° C. for 1 hour.
After the reaction, the fiber was cooled to room temperature, the fiber was washed with a large amount of methanol and pure water, and then dried under vacuum. ATR analysis of the fiber obtained by this reaction treatment revealed that 90
% Was found to be acetylated.

Example 2 N-methylpyrrolidone (NMP) (100 ml) and triethylamine (10 ml) were placed in a 300 ml reactor equipped with a stirrer, a thermometer and a nitrogen inlet tube, and the poly (4-
A mixture in which 4 g of methyl-metaphenylene) terephthalamide fiber was dipped in 100 ml of dioxane was added and stirred at 40 ° C. for 20 minutes, then 2 g of acetyl chloride was added and stirred at 50 ° C. for 1 hour to react. After the reaction, the mixture was cooled to room temperature, the fiber was washed with a large amount of methanol and pure water, and then dried under vacuum. ATR analysis of the fibers obtained by this reaction treatment revealed that 60% of the surface amide groups were acetylated.

Example 3 N-acetylation treatment was carried out in the same manner as in Example 1 except that polymetaphenylene isophthalamide (conex, Teijin Ltd.) having a thickness of 2d, a strength of 5.5 g / d and an elongation of 35% was used. As a result, a fiber was obtained in which 90% of the surface amide groups were N-acetylated.

Example 4 N-acetylation treatment was carried out in the same manner as in Example 2 except that polymetaphenylene isophthalamide (conex, Teijin Ltd.) having a thickness of 2d, a strength of 5.5 g / d and an elongation of 35% was used. As a result, a fiber was obtained in which 60% of the surface amide groups were N-acetylated.

<Light resistance test> In the light resistance test, as Examples 1 to 4 and Comparative Example, the fiber used in Example 1 (Comparative Example 1) and the fiber used in Example 3 (Comparative Example 2) were wound in skeins, respectively. UV long life fade meter FAL5 under the condition of temperature 63 ℃ and humidity 15-16%
Irradiate with H (manufactured by Suga Test Instruments) and
The fiber physical properties after the time irradiation were measured, and the results are summarized in Table 1. From Table 1, the light resistance improving effect of the method of the present invention is clear.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazumi Mizutani 8 -502, Port House, 5 Nishiki-cho, Naka-ku, Yokohama-shi, Kanagawa Prefecture (56) References JP-A-62-91542 (JP, A)

Claims (4)

(57) [Claims] 1. A method for treating a surface of an aromatic polyamide, which comprises subjecting a surface amide group of the aromatic polyamide to N-acylation reaction treatment. 2. The method according to claim 1, wherein the surface amide group of the aromatic polyamide is N-acetylated. 3. The method according to claim 1, wherein 90 mol% or more of the aromatic polyamide is polymetaphenylene isophthalamide. 4. The method according to claim 1, wherein 90% by mole or more of the aromatic polyamide is poly (4-methyl-metaphenylene) terephthalamide.