JP2003049066A - Highly hygroscopic polyamide having improved color tone - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyamide having high hygroscopicity and excellent whiteness. SOLUTION: This polyamide is produced by compounding a polyamide with a polyvinyl pyrrolidone(PVP) polymerized by using an azo-type initiator, an organic peroxide or a persulfate.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a highly moisture-absorbing polyamide having a comfortable feeling of wearing without being sticky when used as clothing and having excellent whiteness. 2. Description of the Related Art Natural fibers represented by cotton, wool, and the like are preferred to have good texture and good comfort such as no feeling of discomfort. The main factor in this comfortable wearing feeling is that the natural fibers have a moderate hygroscopicity. However, natural fibers lack aesthetics such as suppleness, drape property, and glossiness, and are also insufficient in a smooth surface touch, a cool feeling when worn, and the like. In addition, it has insufficient wear resistance and strength, and is not suitable for sports use. On the other hand, polyamide fibers have strength, flexibility, drapability, glossiness, coloring, color fastness,
It has excellent properties such as abrasion resistance and softness. For this reason, it has been favorably used for clothing textiles such as innerwear, sportswear, pantyhose and the like. Although the equilibrium moisture content (hygroscopicity under standard conditions) of polyamide fibers is higher than that of polyester fibers, the hygroscopicity is inferior to that of natural fibers, and the comfort when worn is still insufficient. For this reason, various attempts have been made to improve the moisture absorption properties of polyamide fibers. For example, Japanese Patent Application Laid-Open No. 4-136215 discloses a method for improving spinning stability when producing a hygroscopic polyamide fiber using nylon 4 having excellent hygroscopicity. [0006] Japanese Patent Application Laid-Open No. 56-24426 discloses a method for producing a hygroscopic polyamide fiber by improving the hygroscopic property of the polyamide fiber by graft polymerization. Furthermore, Japanese Patent Publication No. 55-4852 discloses a method for producing a hygroscopic polyamide fiber containing polyvinylpyrrolidone with good spinnability by using a specific spinning method. Japanese Patent Application Laid-Open No. Hei 9-188917 discloses a method for producing a polyamide fiber having an improved color tone by melt-kneading polyvinylpyrrolidone having a pyrrolidone content of 0.1 wt% or less with a polyamide. ing. [0009] However, nylon 4
The moisture-absorbing fiber using swelling has poor dimensional stability due to swelling, and is not satisfactory in practical use. [0010] In addition, the hygroscopic polyamide fiber obtained by graft polymerization has the drawbacks that the dyeability is greatly reduced, no deep dyeing is obtained, and the durability by washing is poor. Further, when a moisture-absorbing polyamide fiber containing polyvinylpyrrolidone is used, it is difficult to obtain a fiber having good whiteness, and there is a problem from the viewpoint of aesthetics for use in clothing. Further, the content of pyrrolidone is 0.1 wt%.
The following method using polyvinylpyrrolidone can provide a polyamide fiber having excellent whiteness, but requires polyvinylpyrrolidone to be polymerized in isopropyl alcohol, and has a problem in terms of economy. As described above, it has been difficult for the conventional techniques to impart sufficient moisture absorption to polyamide fibers without impairing the excellent characteristics inherent in polyamide fibers. Therefore, the present invention solves the above-mentioned drawbacks of the prior art, and achieves the whiteness inherent in polyamide fibers,
A main object of the present invention is to provide a polyamide fiber having excellent characteristics such as high strength, abrasion resistance, softness, gloss characteristics, and clarity in dyeing, and also having high hygroscopicity. [0015] To achieve this object, the highly hygroscopic polyamide of the present invention contains polyvinylpyrrolidone, wherein the polyvinylpyrrolidone is an azo-based initiator,
It is characterized by being polymerized using at least one selected from the group consisting of organic peroxides and persulfates. The polyamide used in the present invention may be any aliphatic polyamide such as polycapramide, polyhexamethylene adipamide, polyhexamethylene sebacamide, polyundecaneamide, or a copolymer based on them. In the case of copolymerized polyamide, the amount of the copolymer component is 1
It may be a small amount such as 5% or less. Among these, polycapramide, polyhexamethylene adipamide, or those mainly containing (for example, 85%)
Above) are preferred. If necessary, known modifiers such as matting agents, light-proofing agents, heat-resistant agents, and antistatic agents may be added to this polyamide as long as the object of the present invention is not impaired. . In the present invention, it is necessary to use a specific polyvinylpyrrolidone. The specific polyvinylpyrrolidone is characterized by being polymerized using at least one selected from the group consisting of an azo initiator, an organic peroxide and a persulfate, and more preferably an azo initiator. It is polymerized using an agent. Conventional polyvinylpyrrolidone was produced using water as a polymerization solvent and hydrogen peroxide as an initiator, and the polyvinylpyrrolidone thus obtained was significantly colored when added to polyamide to form a fiber. Further, the content of pyrrolidone obtained by polymerization in isopropyl alcohol is 0.1 w
A method for obtaining a polyamide fiber having excellent whiteness by using polyvinylpyrrolidone of t% or less is disclosed in
Although it is disclosed in JP 88917B, polymerization in isopropyl alcohol has a problem from the viewpoint of production cost. That is, a polyamide fiber having excellent whiteness can be obtained irrespective of the content of pyrrolidone as an impurity only by selecting a specific initiator in the polymerization of polyvinylpyrrolidone. This will ease and provide economic benefits. DETAILED DESCRIPTION OF THE INVENTION The hygroscopic polyamide fiber of the present invention needs to contain polyvinylpyrrolidone (hereinafter referred to as PVP) in the polyamide in order to obtain desired hygroscopicity. The amount of PVP added to the polyamide is preferably from 1% by weight to 15% by weight based on the polyamide. If it is less than 1% by weight, sufficient hygroscopicity cannot be obtained, and if it is more than 15% by weight, the feeling of stickiness is conversely increased and the wearing comfort is poor. In order to obtain a more excellent color tone, it is necessary to use PVP polymerized using at least one selected from the group consisting of an azo initiator, an organic peroxide and a persulfate. Examples of the azo initiator include 2- (carbamoylazo) isobutyronitrile and 2,2′-azobis (2
-Amidinopropane) dihydrochloride, 2,2′-azobis (2-methyl-N-phenylprolionamidine) dihydrochloride, 2,2′-azobis [2- (N-allylamidino) propane] dihydrochloride , 2,2'-azobis [2- (5
-Hydroxy-3,4,5,6-tetrahydropyrimidin-2-yl) propane] dihydrochloride, 2,2′-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride, 2,2 ′ -Azobis [2-methyl-N- (2-hydroxyethyl) propionamide] and the like, and among these, 2,2'-azobis (2-amidinopropane) dihydrochloride is preferable from the viewpoint of the decomposition temperature. Examples of the organic peroxide include diacyl peroxides such as lauroyl peroxide and benzoyl peroxide, peroxyesters such as t-butylperoxy-2-ethylhexanoate, and 2,2, -bis (t-butylperoxy) butane. And dialkyl peroxides such as di-t-butyl peroxide and hydroxyperoxides such as t-butyl hydroxy peroxide. As the persulfate, for example, potassium persulfate,
Examples include sodium persulfate and ammonium persulfate. The amount of these initiators to be added is not particularly limited, but is preferably 0.01 to 10% by weight based on the monomer used as the raw material for PVP. The azo initiator, the organic peroxide, and the persulfate may be used in combination, and further, a reducing agent may be used in combination with the azo initiator as the redox initiator. As a method of polymerizing PVP, an azo initiator,
There is no particular limitation as long as the polymerization is carried out using either an organic peroxide or a persulfate, and aqueous polymerization, solution polymerization, suspension polymerization, precipitation polymerization, bulk polymerization and the like can be used. There is no limitation on the content of pyrrolidone contained as a by-product in PVP used in the present invention, and it may be contained in an amount of 0.1 wt% or more based on PVP. The polyamide fiber of the present invention needs to contain a predetermined amount of polyvinylpyrrolidone (hereinafter abbreviated as PVP). The amount of PVP added is from 1% by weight to 15% by weight.
Or less (vs. polyamide), more preferably 2% by weight or more and 7% by weight or less. In order to impart sufficient hygroscopicity to the polyamito fiber, the amount of PVP must be at least 1% by weight. Conversely, if the amount is too large, the feeling of stickiness becomes strong and the comfort when worn is inferior. This PVP may be added at the time of polymerization of the polyamide, before or at the time of spinning, that is, at any stage before the spinning of the polyamide. And a method of kneading the mixture into polyamide, a method of blending at the time of spinning, and the like. Here, a method for measuring various characteristic values in the present invention will be described. <Pyrrolidone content> To 100 mg of a fiber sample, 3 ml of hexafluoroisopropanol and 1 ml of chloroform were added to dissolve the fiber. Ethanol was added to the obtained solution to reprecipitate the polymer component, and the solution was dissolved in 20 ml. The solution components are subjected to gas chromatogram analysis by a conventional method. The device was GC14A (manufactured by Shimadzu Corporation), and the column was NB-1 (1
5m) is used. For the determination of pyrrolidone, a valerolactam calibration curve is prepared in advance and used. The pyrrolidone content is determined by the following equation. Pyrrolidone content (wt%) = [(GC peak area / calibration curve coefficient) (mg / ml) x solution amount (ml) / sample amount (mg)] x 100 <K value> PVP is a 1% concentration aqueous solution. , And its relative viscosity is measured and determined by the Fikenscher equation. logZ = C [75 k ² /(1+1.5 kC) + k] where Z: relative viscosity of the aqueous solution having a concentration C, k: K value × 10
^-3 , C: concentration of aqueous solution (W / V%). <Maximum moisture absorption, standard moisture absorption> A 27 gauge tubular knitted fabric is prepared from the sample fibers. After scouring the produced sample knitted fabric to remove the oil agent, about 1 g thereof is put into a glass weighing bottle (tare weight F) and dried in a dryer at 110 ° C. for 2 hours. After drying, the bottle is allowed to cool in a desiccator for 30 minutes in a sealed state, and then the total weight (K) of the weighing bottle containing the knitted sample is measured. Then, it is placed in a constant temperature and humidity chamber set at 20 ° C. and 65% RH in an open state and left for 24 hours. Thereafter, the container is sealed again and left in a desiccator for 30 minutes, and then the total weight (H) of the weighing bottle containing the sample knitted fabric is measured. Subsequently, the container was left open for 24 hours in a constant temperature and humidity chamber set at 30 ° C. and 90% RH.
The total weight (S) of the weighing bottle containing the sample knitted fabric is measured. From the above weight values (K, H, S), it is calculated by the following equation. Maximum moisture absorption = [(S−K) / (K−F)] × 100
(%) Standard moisture absorption = [(HK) / (KF)] × 10
0 (%) <Whiteness> A knitting knitted fabric having a knitting density of 45 yarns / inch is created using a 27 knit knitting machine. The obtained tubular knitted fabric is folded in two, and the lightness, a value, and b value are measured by a color meter, and whiteness is determined by the following equation. W (whiteness) = 100 − [(100−L) ² + a ² + b
² ] ^1/2 (Synthesis Example 1) 120 parts by weight of ion-exchanged water is charged into a reactor equipped with a reflux tube, a temperature sensor, a nitrogen inlet, a monomer inlet, and an initiator outlet. 60 parts by weight of N-vinylpyrrolidone as a monomer in the monomer dropping device,
1.38 parts by weight of V-50 (azo-based initiator, manufactured by Wako Pure Chemical Industries, Ltd.) as an initiator solution in an initiator dropping device was added to ion-exchanged water 20.
An aqueous solution dissolved in parts by weight is charged. The temperature is raised while blowing nitrogen through the nitrogen inlet, and if reflux is confirmed, polymerization is carried out while simultaneously dropping the monomer and the initiator solution from the monomer dropping port and the initiator dropping port over 3 hours and 30 minutes. After the completion of dropping, the mixture was aged for 30 minutes.
One part by weight of a 7% aqueous solution is added, the temperature of the system is maintained at 95 or more, and the remaining N-vinylpyrrolidone monomer is hydrolyzed. The reaction was completed 2 hours after the addition of oxalic acid, and after standing to cool, a basic compound such as guanidine carbonate was added to raise the pH of the system to 7.
Adjust near. The aqueous solution of polyvinylpyrrolidone thus obtained was dried by a spray drier to obtain a white powder of polyvinylpyrrolidone. (Hereinafter PVP-1) The K value of PVP-1 was 29.8. (Synthesis Example 2) 2 wt% aqueous hydrogen peroxide 2 as an initiator solution
A white powder of polyvinylpyrrolidone was obtained in exactly the same manner as in Synthesis Example 1 except that 0 parts by weight was used. (Hereinafter PVP-
2) The K value of PVP-2 was 30.5. (Example 1) PVP-1 was used as PVP. This PVP was kneaded and mixed with nylon 6 having 98% sulfuric acid relative viscosity ηr of 2.72 using an extruder (φ40 mm, bi-axial, biaxial), extruded in a gut shape, and pelletized after cooling to obtain a PVP concentration of 30 wt. % Master polymer chip. At this time, the oxygen concentration was reduced to 8% or less by flowing nitrogen through the hopper and the cylinder. The nylon 6 chips and the above-mentioned master polymer chips were dried in a usual manner while blending them in a predetermined ratio in a rotary vacuum dryer. The content of PVP with respect to nylon 6 in the blend chip obtained by drying was set to 3, 7, and 15 wt%. Each of the blended chips was melted at 270 ° C., discharged from a 13-hole Y-type die, fed at a spinning speed of 1,300 m / min, a draw ratio of 2.3, and a winding speed of 30.
The PVP-containing polyamide multifilament having 30 denier and 13 filaments in a trilobal section having a degree of deformation of 2.6 was obtained by direct spinning and drawing at a speed of 00 m / min. As shown in Table 1, all of the samples had sufficiently low whiteness, a high maximum moisture absorption of 8% or more, and a large difference of 4% or more between the maximum moisture absorption and the standard moisture absorption. Both moisture absorption properties were excellent. (Comparative Example 1) A PVP-containing polyamide multifilament was obtained in exactly the same manner as in the example except that PVP-1 was replaced with PVP-2. All samples were excellent in hygroscopicity but inferior in whiteness. [Table 1]

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C08L 39/06 C08L 39/06 D01F 6/90 311 D01F 6/90 311D F-term (reference) 4J002 BJ002 CL011 CL031 FD202 GK01 4J015 AA02 AA07 AA10 BA02 BA03 BA04 BA05 BA06 BA07 BA14 4J100 AQ08P CA01 DA37 FA03 JA11 4L035 BB31 EE05 GG01 LC08

Claims (1)

Claims: 1. A polyamide containing polyvinylpyrrolidone, wherein the polyvinylpyrrolidone is an azo-based initiator,
A highly hygroscopic polyamide which is polymerized using at least one selected from the group consisting of organic peroxides and persulfates.