Fluorescent elastic yarn and method for producing the same

Abstract

Disclosed is a fluorescent elastic yarn and method for producing the same. The fluorescent elastic yarn can fluoresce sufficiently to allow a thin elastic yarn to be seen by the naked eye when ultraviolet light is irradiated to the fluorescent elastic yarn by adding a novel organic additive to a polymer or a spinfinish. Therefore, the fluorescent elastic yarn of the present invention is advantageous in that production of inferior covered yarns is prevented.

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates, in general, to a fluorescent elastic yarn and a method for producing the same and in particular, to a fluorescent elastic yarn which can fluoresce sufficiently to allow a thin elastic yarn to be seen by the naked eye when ultraviolet light is irradiated to the fluorescent elastic yarn by adding a novel organic additive to a polymer or a spinfinish, and a method of producing the same.

[0003] 2. Description of the Prior Art

[0004] An elastic yarn has been applied to various fields, and a process of knitting and weaving the elastic yarn covered with a natural fiber has been widely used in the art. Various types of elastic yarns, for example, a core spun yarn in which cotton or a rayon fiber is covered on the elastic yarn, and a covered yarn in which a synthetic fiber such as nylon and polyester is covered on the elastic yarn, are used to produce elastic textile fabrics or knitted goods requiring elasticity.

[0005] However, there is a problem during a covering process of the elastic yarn in that a breakage of the elastic yarn cannot be discovered in good time, and so inferior products having only the covered yarn wound without the elastic yarn may be produced. This problem causes a reduction in productivity of the covered elastic yarn and a waste of the covered yarns. Accordingly, there remains a need for the development of a novel method capable of finding a breakage of the elastic yarn in good time.

[0006] A conventional method of finding a breakage of the elastic yarn is based on a principle that titanium-based or magnesium-based inorganic additives added into the elastic yarn emit a dark violet ray when irradiated by ultraviolet light. However, the inorganic additives are not only added into the elastic yarn in order to avoid the above problem, but also added into the elastic yarn so as to improve dulling effect and anti-blocking property, and so the problem cannot be overcame basically. Furthermore, the conventional method is disadvantageous in that when thickness of the elastic yarn is less than 40 deniers, or a small capacity device such as a portable UV radiator is used to discriminate breaking of the elastic yarn in a work place, it is almost impossible to find the breakage.

SUMMARY OF THE INVENTION

[0007] Therefore, it is a feature of the present invention to provide a fluorescent elastic yarn which can be discriminated by fluorescence when ultraviolet light is irradiated to it.

[0008] It is another feature of the present invention to provide a method for producing the fluorescent elastic yarn.

[0009] It is the other feature of the present invention to provide a fluorescent elastic yarn covered with hard fiber.

[0010] In accordance with an aspect of the present invention, there is provided a fluorescent elastic yarn comprising 0.001 to 20 wt % of a fluorescent brightener.

[0011] In accordance with another aspect of the present invention, there is provided a method for producing a fluorescent elastic yarn comprising the step of spinning a polyurethane-urea copolymer, wherein a fluorescent brightener is mixed with the polyurethane-urea copolymer in an amount of 0.001 to 20 wt %.

[0012] In accordance with another aspect of the present invention, there is provided a method for producing a fluorescent elastic yarn comprising the step of spinning a polyurethane-urea copolymer, wherein a spinfinish having a fluorescent brightener dispersed therein is applied to a spun elastic yarn in such an amount that a content of the fluorescent brightener in the resulting elastic yarn ranges from 0.001 to 20 wt %.

[0013] In accordance with the other aspect of the present invention, there is provided a method for producing a covered fluorescent elastic yarn, comprising the step of covering a core yarn, wherein the core yarn is the fluorescent elastic yarn.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0014] A segmented polyurethane-urea copolymer useful for production of a fluorescent elastic yarn of the present invention is produced by reacting organic diisocyanate with polydiol to produce a prepolymer, and then dissolving the prepolymer in an organic solvent and reacting with diamine and monoamine.

[0015] The organic diisocyanate used to produce the segmented polyurethane-urea copolymer includes, not limited to, diphenylmethane-4,4′-diisocyanate, hexamethylenediisocyanate, toluenediisocyanate, butylenediisocyanate, and hydrogenated P,P-methylenediisocyanate.

[0016] The polydiol used to produce the segmented polyurethane-urea copolymer includes, not limited to, polytetramethylene ether glycol, polypropylene glycol, and polycarbonate diol.

[0017] Furthermore, a diamine such as ethylene diamine, propylene diamine, and hydrazine can used as a chain extender, and a monoamine such as diethylamine, monoethanol amine, and dimethyl amine can be used as a chain termination agent.

[0018] Useful for covering the elastic yarn according to the present invention may be cotton, rayon, nylon, polyester, or cellulose.

[0019] A fluorescent brightener characteristically added to an elastic yarn in the present invention may be mixed with a polymer used as a raw material of the elastic yarn before the elastic yarn is spun. Alternatively, the fluorescent brightener may be added into a spinfinish which is applied to a spun elastic yarn after spinning of the elastic yarn. The fluorescent brightener is added to the elastic yarn in such an amount that a fluorescent brightener content ranges from 0.001 to 20 wt % in the resulting elastic yarn.

[0020] When the fluorescent brightener content is less than 0.001 wt %, a fluorescent effect is poor. On the other hand, when the content is more than 20 wt %, dispersability of the fluorescent brightener in a polymer or spinfinish is poor and so the fluorescence of the fluorescent elastic yarn is non-uniform though the fluorescence is absolutely bright, and the fluorescent elastic yarn cannot be produced economically due to the heavy cost of brightener.

[0021] The fluorescent brightener used in the present invention include, not limited to, a stilbene-based fluorescent brightener, a pyrazolone-based fluorescent brightener, an imidazole-based fluorescent brightener, an oxazole-based fluorescent brightener, a coumarin-based fluorescent brightener, a rhodamine-based fluorescent brightener, and a fluorescein-based fluorescent brightener. Specific examples of each fluorescent brightener are as follows:

[0022] Stilbene-based fluorescent brightener: C.I.(Color Index) Fluorescent Brighteners No. 24, 77, 84, 85, 90, 97, 132, 151, 153, 154, and 166, which are kinds of ((Bis)triazinylaminostilbene)) or derivatives thereof;

[0023] Pyrazolone-based fluorescent brightener: C.I. Fluorescent Brighteners No. 54 and 124;

[0024] Imidazole-based fluorescent brightener: C.I. Fluorescent Brighteners No. 45, 133, 140, 150, 189, 228, and 2-isopropylimidazole (CAS(Chemical Abstract Society)# 36947-68-9);

[0025] Oxazole-based fluorescent brightener: C.I. Fluorescent Brighteners No. 170, 171, 219, 258, 259, and (2,2′-2,5-diophenydil)bis[5-(1,1-dimethylethyl)]-benzoxazol (usually referred to as ‘uvitex OB’);

[0026] Coumarin-based fluorescent brightener: C.I. Fluorescent Brighteners No. 52, 69, 78, 91, 130, 152, 156, 162, Coumarin 1(CAS# 91-44-1, 7-diethylamino-4-methyl coumarin), and Coumarin 6(CAS# 38215-36-0, 3-(2-benzotiazolyl)-7-diethylamino coumarin);

[0027] Rhodamine-based fluorescent brightener: Rhodamine B (CAS# 81-88-9, N-[9-(2-carboxyphenyl)-6-diethylamino-3H-xanthen-3-ylidene]-N-ethylethanammonium chloride), and Rhodamine isocyanate (CAS# 36877-69-7); and

[0028] Fluorescein-based fluorescent brightener: Fluorescein (CAS# 2321-07-5), and Fluorescein isothiocyanate (CAS# 3326-32-7).

[0029] It is preferable that the fluorescent brightener is dispersed in an organic solvent prior to being mixed with a polymer or spinfinish. The organic solvent includes, not limited to, methanol and hexylene glycol (CAS# 107-41-5, 2-methyl-2,4-pentandiol).

[0030] According to the present invention, additives such as a UV stabilizer, an antioxidant, a NOx gas yellowing resistance agent, an anti-blocking agent, a dye fastness improver, a chlorine-resisting agent, and a dulling agent may be added to the elastic yarn during dry spinning of the elastic yarn.

[0031] When the fluorescent brightener is added to a dissolved polymer before spinning of the elastic yarn, the fluorescent brightener displays an eternal fluorescent effect under ultraviolet light, and so the fluorescent elastic yarn can be applied to clothes for a special use recognized by a UV radiator. Alternatively, when the fluorescent elastic yarn is produced using the spinfinish containing the fluorescent brightener, the fluorescent elastic yarn is advantageous in that the fluorescent elastic yarn is readily visually inspected because the fluorescent brightener is coated on the surface of the elastic yarn. Also, the knitted or woven fabric applied with the fluorescent elastic yarn mentioned above can be used for various purpose according to user's requirements, because the fluorescent brightener can be detached from the elastic yarn very easily under scoring and post processing of the fabric.

[0032] A better understanding of the present invention may be obtained by reading the following examples which are set forth to illustrate, but are not to be construed to limit the present invention.

EXAMPLE 1

[0033] 518 g of diphenylmethane-4,4′-diisocyanate was reacted with 2328 g of polytetramethylene ether glycol (molecular weight: 1800) under a nitrogen gas atmosphere at 85° C. for 90 min to produce a prepolymer containing isocyanate groups positioned at both terminations thereof. The prepolymer thus produced was cooled to room temperature, and 4643 g of dimethylacetamide was added to the cooled prepolymer to produce a prepolymer solution.

[0034] After that, a solution, in which 54 g of propylene diamine and 9.1 g of diethylamine were dissolved in 1889 g of dimethylacetamide, was added to the prepolymer solution at 10° C. or less to produce a segment polyurethane-urea copolymer solution.

[0035] Additives such as a UV stabilizer, an antioxidant, a yellowing resistance agent, a dye fastness improver, a magnesium-based anti-blocking agent, and a titanium-based dulling agent were added to the above segmented polyurethane-urea copolymer solution, and Coumarin 1 (CAS# 91-44-1, 7-diethyl amino-4-methylcoumarin) dispersed in hexylene glycol (CAS# 107-41-5, 2-methyl-2,4-pentanediol) in a weight ratio of 2:8 was added to the polymer solution in such an amount that a Coumarin 1 content was 5 wt % based on the resulting polymer solid. The resulting polymer was subjected to a defoaming process, drawn at a spinning temperature of 250° C. by a dry spinning process, and wound to produce a polyurethane-urea elastic yarn with a thickness of 10 deniers. The elastic yarn was covered with a polyester false twist yarn with a thickness of 75 deniers with the use of conventional covering machines. Physical properties of the elastic yarn and the covered elastic yarn were evaluated, and results are described in Table 1.

EXAMPLES 2 TO 4

[0036] The procedure of example 1 was repeated except that the resulting elastic yarns were 20, 40, and 140 deniers in thickness. Physical properties of the resulting elastic yarns are described in Table 1.

EXAMPLE 5

[0037] 518 g of diphenylmethane-4,4′-diisocyanate was reacted with 2328 g of polytetramethylenether glycol (molecular weight: 1800) under a nitrogen gas atmosphere at 85° C. for 90 min to produce a prepolymer containing isocyanate groups positioned at both terminations thereof. The prepolymer thus produced was cooled to room temperature, and 4643 g of dimethylacetamide was added to the cooled prepolymer to produce a prepolymer solution.

[0038] After that, a solution, in which 54 g of propylene diamine and 9.1 g of diethylamine were dissolved in 1889 g of dimethylacetamide, was added to the prepolymer solution at 10° C. or less to produce a segmented polyurethane-urea copolymer solution.

[0039] Additives such as a UV stabilizer, an antioxidant, a yellowing resistance agent, a dye fastness improver, a magnesium-based anti-blocking agent, and a titanium-based dulling agent were added to the above segmented polyurethane-urea copolymer solution, and the resulting polyurethane-urea copolymer solution was subjected to a defoaming process and drawn at a spinning temperature of 250° C. by a dry spinning process. Coumarin 1 (CAS# 91-44-1, 7-diethyl amino-4-methylcoumarin) was dispersed in hexylene glycol (CAS# 107-41-5, 2-methyl-2,4-pentanediol) in a weight ratio of 2:8 to produce a dispersion liquid, and the dispersion liquid was added to the resulting polyurethane-urea copolymer polymer solution in such an amount that the dispersion liquid is 10 wt % based on a spinfinish generally used in winding the elastic yarn, for example, comprising polydimethylsiloxane and pure. 5 wt % spinfinish based on the elastic yarn was applied to a surface of the elastic yarn to produce the resulting elastic yarn with a thickness of 10 deniers. The fluorescent brightener content in the resulting elastic yarn was 0.1 wt %. The resulting elastic yarn was covered with a polyester false twist yarn with a thickness of 75 deniers with the use of conventional covering machines. Physical properties of the elastic yarn and the covered elastic yarn were evaluated, and results are described in Table 1.

EXAMPLES 6 TO 8

[0040] The procedure of example 5 was repeated except that the resulting elastic yarns were 20, 40, and 140 deniers in thickness. Physical properties of the resulting elastic yarns and covered elastic yarns were evaluated, and results are described in Table 1.

COMPARATIVE EXAMPLES 1 TO 4

[0041] The procedure of example 1 was repeated to produce the resulting elastic yarns of 10, 20, 40, and 140 deniers except that a fluorescent dispersion liquid was not applied to the elastic yarn. Physical properties of the resulting elastic yarns and covered elastic yarns were evaluated, and results are described in Table 1.

EXAMPLES 9 TO 10

[0042] The procedure of example 3 was repeated except that each Coumarin 1 added to a polymer solution was 0.001 and 20 wt % based on the resulting polymer solid.

COMPARATIVE EXAMPLES 5 TO 6

[0043] The procedure of example 3 was repeated except that each Coumarin 1 added to a polymer solution was 0.0001 and 25 wt % based on the resulting polymer solid.

EXAMPLE 11

[0044] The procedure of example 7 was repeated except that 0.1 wt % dispersion liquid having a fluorescent brightener dispersed therein based on a spinfinish was added to an elastic yarn, 5 wt % spinfinish based on the elastic yarn was applied to a surface of the elastic yarn and the resulting mixture was wound to produce the resulting elastic yarn with a thickness of 40 deniers, and a fluorescent brightener content in the resulting elastic yarn was 0.001 wt %.

COMPARATIVE EXAMPLE 7

[0045] The procedure of example 7 was repeated except that 0.01 wt % dispersion liquid having a fluorescent brightener dispersed therein based on a spinfinish was added to an elastic yarn, 5 wt % spinfinish based on the elastic yarn was attached to a surface of the elastic yarn and the resulting mixture was wound to produce the resulting elastic yarn with a thickness of 40 deniers, and a fluorescent brightener content in the resulting elastic yarn was 0.0001 wt %. 1 TABLE 1 Luminosity under UV (25 lux) Measurement by Visual Visual Luxmeter (lux) inspection inspection (whole elastic (a string of (a string of Deniers (d) yarn package) elastic yarn) covered yarn) Whiteness Ex. 1 10 4˜6 Possible Possible ⊚ (fluorescent light) Ex. 2 20 4˜6 Possible Possible ⊚ (fluorescent light) Ex. 3 40 4˜6 Possible Possible ⊚ (fluorescent light) Ex. 4 140 4˜6 Possible Possible ⊚ (fluorescent light) Ex. 5 10 8˜10 Possible Possible ⊚ (fluorescent light) Ex. 6 20 8˜10 Possible Possible ⊚ (fluorescent light) Ex. 7 40 8˜10 Possible Possible ⊚ (fluorescent light) Ex. 8 140 8˜40 Possible Possible ⊚ (fluorescent light) Ex. 9 40 1˜2 Possible Possible ◯ (fluorescent light) Ex. 10 40 35˜40 Possible Possible ⊚ (fluorescent light) Ex. 11 40 1˜2 Possible Possible ◯ (fluorescent light) Co. Ex. 1 10 0˜1 Impossible Impossible &Dgr; (dark violet) Co. Ex. 2 20 0˜1 Impossible Impossible &Dgr; (dark violet) Co. Ex. 3 40 0˜1 Impossible Impossible &Dgr; (dark violet) Co. Ex. 4 140 0˜1 Possible Possible &Dgr; (dark violet) Co. Ex. 5 40 0˜1 Impossible Impossible &Dgr; (fluorescent light) Co. Ex. 6 40 40˜45 Possible Possible ⊚ (fluorescent light) Co. Ex. 7 40 0˜1 Impossible Impossible &Dgr; (fluorescent light) ⊚: excellent, ◯: good, &Dgr;: poor

[0046] From the results of Table 1, it can be seen that a thin elastic yarn of 40 d or less without the fluorescent brightener is difficult to be visually inspected under UV, and when a fluorescent brightener content based on the resulting polymer is 20 wt % or more as in the case of example 6, the elastic yarn has an excellent fluorescent effect, but has disadvantages of poor unwinding property of and poor dispersibility of a fluorescent substrate.

EXAMPLES 12 TO 18

[0047] The procedure of example 7 was repeated except that a fluorescent brightener and a dispersing agent are different from each other as shown in Table 2. Physical properties of the resulting elastic yarns and covered elastic yarns were evaluated, and results are described in Table 2. 2 TABLE 2 C.I. # or Luminosity Fluorescent commercial Dispersing under 25 lux White- Ex. brightener name agent UV (lux) ness 12 Stilbene 24 Methanol 2˜4 ◯ (blue violet) 77 Hexylene 5˜6 ⊚ glycol 84 Methanol 5˜6 ⊚ (blue violet) ⊚ 85 Methanol 4˜6 ⊚ (blue violet) 90 Methanol 5˜6 ⊚ (blue violet) 97 Hexylene 5˜6 (blue) ⊚ glycol 132 Hexylene 5˜6 (blue) ⊚ glycol 151 Methanol 2˜4 ◯ (red blue) 153 Methanol 2˜4 (blue) ◯ 154 Methanol 5˜6 (blue) ⊚ 166 Methanol 5˜6 ⊚ (green blue) 13 Pyrazolone 54 Methanol 2˜3 ◯ (green blue) 124 Methanol 2˜3 (blue) ◯ 45 Methanol 4˜6 (blue) ⊚ 133 Methanol 4˜6 (blue) ⊚ 140 Methanol 4˜6 (blue) ⊚ 150 Methanol 5˜7 (blue) ⊚ 14 Imidazole 189 Methanol 4˜6 (blue) ⊚ 228 Hexylene 4˜6 (blue) ⊚ glycol 2-isopropyl Hexylene 4˜6 (blue) ⊚ imidazole glycol 170 Methanol 2˜4 (blue) ◯ 171 Methanol 2˜4 (blue) ◯ 219 Acetone 1˜2 &Dgr; (red blue) 15 Oxazole 258 Acetone 1˜2 &Dgr; (blue violet) 259 Methanol 2˜4 (blue) ◯ 16 Coumarin 52 Methanol 3˜6 ⊚ (blue violet) 69 Acetone 3˜6 ⊚ (blue violet) 78 Acetone 3˜6 ⊚ (blue violet) 91 Acetone 3˜6 ⊚ (blue violet) 130 Hexylene 3˜6 (violet) ⊚ glycol 152 Acetone 3˜6 ⊚ (green blue) 156 Acetone 3˜6 (blue) ⊚ 162 Acetone 3˜6 (blue) ⊚ Coumarin 1 Hexylene  8˜10 ⊚ glycol Coumarin 6 Hexylene  8˜10 ⊚ glycol 17 Rhodamine Rhodamine B Acetone 6˜8 (blue) ⊚ Rhodamine Acetone 6˜8 (blue) ⊚ isocyanate 18 Fluorescein Fluorescein Acetone 5˜7 (green) ⊚ Fluorescein Acetone 5˜7 (green) ⊚ isocyanate ⊚: excellent, ◯: good, &Dgr;: poor

[0048] As described above, the present invention is advantageous in that a fluorescent elastic yarn of this invention can be visually inspected under UV even though the elastic yarn is covered with a polyester false twist yarn, and so it can be discriminated whether a thin elastic yarn of 10 deniers is present or not, thereby production of inferior covered yarn (No presence of elastic yarn) is minimized and productivity of the fluorescent elastic yarn is improved in a downstream process of producing the fluorescent elastic yarn.

[0049] The present invention has been described in an illustrative manner, and it is to be understood that the terminology used is intended to be in the nature of description rather than of limitation. Many modifications and variations of the present invention are possible in light of the above teachings. Therefore, it is to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

Claims

1. A fluorescent elastic yarn comprising 0.001 to 20 wt % of a fluorescent brightener.

2. A method for producing a fluorescent elastic yarn comprising the step of spinning a polyurethane-urea copolymer,

wherein a fluorescent brightener is mixed with the polyurethane-urea copolymer in an amount of 0.001 to 20 wt %.

3. A method for producing a fluorescent elastic yarn comprising the step of spinning a polyurethane-urea copolymer,

wherein a spinfinish having a fluorescent brightener dispersed therein is applied to a spun elastic yarn in such an amount that a content of the fluorescent brightener in the resulting elastic yarn ranges from 0.001 to 20 wt %.

4. The method according to claim 2, wherein the fluorescent brightener is selected from the group consisting of a stilbene-based fluorescent brightener, a pyrazolone-based fluorescent brightener, an imidazole-based fluorescent brightener, an oxazole-based fluorescent brightener, a coumarin-based fluorescent brightener, a rhodamine-based fluorescent brightener and a fluorescein-based fluorescent brightener.

5. The method according to claim 3, wherein the fluorescent brightener is selected from the group consisting of a stilbene-based fluorescent brightener, a pyrazolone-based fluorescent brightener, an imidazole-based fluorescent brightener, an oxazole-based fluorescent brightener, a coumarin-based fluorescent brightener, a rhodamine-based fluorescent brightener and a fluorescein-based fluorescent brightener.

6. A method for producing a covered fluorescent elastic yarn, comprising the step of covering a core yarn,

wherein the core yarn is the fluorescent elastic yarn according to claim 1.

7. The method according to claim 6, wherein the fluorescent elastic yarn is covered with at least one selected from the group consisting of cotton, rayon, nylon, polyester and cellulose.

8. A covered fluorescent elastic yarn produced through the method according to claims 6 and 7.

9. A core spun yarn produced through the method according to claim 5.