High-fastness UV-curable coating method for spun yarn for denim fabric

Abstract

The present invention relates to a high-fastness UV-curable coating method for spun yarn for denim fabric, the method replacing a conventional dyeing process, thereby having limitations in color implementation and providing excellent flame-retardant performance. According to the present invention, the high-fastness UV-curable coating method for spun yarn can be provided, the method using an ultraviolet-curable yarn dyeing technique in which a 100% solid UV resin, rather than a reduction dye and a dye solution used in a conventional dyeing process of spun yarn that can be used for denim fabric, is used so that harmful volatile organic compounds (VOCs) are not emitted, solving environmental problems that occur during manufacturing by not using solvents such as water, and enabling high productivity and energy consumption reduction to be achieved through rapid polymerization.

Description

High-fastness UV-curing coating method for spun yarn for denim fabric

[0001] The present invention relates to a method for high-fastness UV curing coating of spun yarn for denim fabric having excellent flame retardancy and color realization limitations by replacing existing dyeing processes.

[0002] As the importance of eco-friendly technologies and products grows globally, environmental hazards, such as energy consumption and wastewater, in the apparel and industrial fabric dyeing markets are emerging as serious social and economic issues. In particular, the apparel industry accounts for 10% of global greenhouse gas emissions and 20% of wastewater generation. Furthermore, clothing emits approximately 12 billion tons of carbon annually, accounting for 10% of global carbon emissions.

[0003] In terms of the amount of water used in the dyeing process, about 2,700 L of water is used to make one T-shirt for general clothing, and about 7,000 to 11,000 L of water is used to make one pair of jeans.

[0004] In the dyeing process of denim fabric for jeans, the dyes commonly used are dark indigo (Indigo blue dye) and sulfur dyes of the reduction dye series. The reduction dyes are insoluble in water, so they can be dyed onto fibers by reducing them using an alkaline reducing agent, Hydrosulfite. After dyeing, they are reduced to a colorless dye through oxidation and become insoluble. During this oxidation process, the colorless dye is reduced to a colorless dye, and the unique indigo color of jeans appears. As these reduction and oxidation processes are repeated continuously, the dyeing concentration becomes darker, so the process is repeated several times depending on the desired color.

[0005] This dyeing process is generally called vatting, and after dyeing, the denim fabric and jeans can have various colors and effects through the washing process. As this process is repeated, not only does a lot of water are used, but in the case of indigo dye, its very large molecular structure prevents it from penetrating deep into the fiber and instead remains adsorbed in a round shape on the surface of the fiber. This causes the indigo molecules dyed on the surface to easily fall off due to washing and friction.

[0006] Meanwhile, demand for denim fabrics is increasing not only for apparel but also for industrial workwear. Workwear requiring flame retardancy is primarily divided into firefighting uniforms, industrial workwear, and other types (such as rescue teams and medical services). For industrial workwear, demand is growing for workwear made with aramid, a material with flame retardancy directly related to safety, rather than non-functional cotton. This is because the workwear market is increasingly demanding design elements in addition to basic performance requirements such as breathability, deodorization, and comfort, leading to a preference for products that can be used as everyday wear in addition to workwear.

[0007] In this way, cotton spun yarn or aramid spun yarn, which is the raw material for denim fabric, has problems such as high energy consumption, generation of dyeing wastewater, friction, and reduced color fastness when dyed using existing commercial dyes, other additives, and hot water dyeing processes. Therefore, research and development is needed to improve the problems of the existing dyeing process using reducing dyes.

[0008] [Prior Art Literature]

[0009] [Patent Document]

[0010] (Patent Document 0001) Republic of Korea Patent Registration No. 10-1591041 (February 4, 2016)

[0011] announcement)

[0012] Therefore, the present invention provides a method for high-fastness UV curing coating of spun yarn that can be used not only for clothing but also as industrial workwear material, by using a UV curing dyeing technology using a 100% solid UV resin instead of a reducing dye and dye solution used in the existing dyeing process of spun yarn for denim fabric, which does not emit harmful volatile substances (VOCs) and does not use a solvent such as water, thereby solving environmental problems arising in the manufacturing process and achieving high productivity and reduced energy consumption due to high-speed polymerization.

[0013] Therefore, according to the present invention, after preparing a UV-curable coating solution by mixing a UV-curable oligomer, a UV-curable monomer, a commercially available phosphorus oligomer, a pigment, and a photoinitiator,

[0014] After padding the spun yarn with the above UV curing coating solution,

[0015] After passing through a compression roller with a constant pressure to form a thin film coating layer on the surface of the spun yarn,

[0016] A method for high-fastness UV curing coating of a spun yarn for denim fabric is provided, characterized in that the coated spun yarn is advanced vertically from the surface and irradiated with ultraviolet rays to cure the ultraviolet curing coating solution.

[0017] Therefore, according to the present invention, a method for high-fastness UV curing coating of spun yarn can be provided that solves environmental problems arising in the manufacturing process by not emitting harmful volatile substances (VOCs) and not using solvents such as water, by using a UV curing dyeing technology using a 100% solid UV resin instead of a reducing dye and dye solution used in the existing dyeing process of spun yarn that can be used for denim fabric, and that can achieve high productivity and reduced energy consumption due to high-speed polymerization.

[0018] Figure 1 is a photograph of cotton spun yarn manufactured by the high-fastness UV curing coating method of the present invention.

[0019] Figure 2 is a test report of cotton spun yarn manufactured by the high-fastness UV curing coating method of the spun yarn of the present invention.

[0020] Figure 3 is a photograph of a meta-aramid spun yarn manufactured by the high-fastness UV curing coating method of the spun yarn of the present invention.

[0021] Figure 4 is a test report of meta-aramid spun yarn manufactured by the high-fastness UV curing coating method of the spun yarn of the present invention.

[0022] Figure 5 is a photograph of a denim fabric woven with cotton spun yarn manufactured by the high-fastness UV curing coating method of the spun yarn of the present invention.

[0023] Figure 6 is a photograph of a denim fabric woven from meta-aramid spun yarn manufactured by the high-fastness UV curing coating method of the spun yarn of the present invention.

[0024] Hereinafter, the present invention will be described in more detail.

[0025] The present invention relates to a method for high-fastness UV curing coating of spun yarn for denim fabric, and relates to a method for solving environmental problems arising in the manufacturing process by not emitting harmful volatile substances (VOCs) and not using solvents such as water through a UV curing yarn dyeing technology using a 100% solid UV resin instead of a reducing dye and dyeing solution used in the existing dyeing process of spun yarn that can be used for denim fabric, and achieving high productivity and reduced energy consumption through high-speed polymerization.

[0026] In the present invention, the ultraviolet curable coating solution for coating the spun yarn uses an ultraviolet curable coating solution that mixes an ultraviolet curable oligomer, an ultraviolet curable monomer, a commercialized phosphorus oligomer, a pigment, and a photoinitiator.

[0027] In the present invention, the composition of the ultraviolet curable coating solution is different depending on the type of spun yarn to be coated. First, when the spun yarn is cotton spun yarn, the ultraviolet curable coating solution is preferably a mixture of 25 to 32 wt% of ultraviolet curable oligomer, 32.5 to 47.5 wt% of ultraviolet curable monomer, 15 to 20 wt% of commercialized phosphorus oligomer, 10 to 12 wt% of pigment, and 2.5 to 3.5 wt% of photoinitiator.

[0028] When the UV-curable oligomer is less than 25 wt%, the coating layer may peel off due to friction caused by a decrease in adhesive strength, and when it exceeds 32 wt%, the viscosity of the UV-curable coating solution may increase, causing problems with coating uniformity and a hard touch as a denim fabric due to an increase in the coating thickness. When the UV-curable monomer is less than 32.5 wt%, a problem due to a hard touch after coating may occur, and when it exceeds 47.5 wt%, problems with high color development and friction fastness may occur. When the commercialized phosphorus oligomer is less than 15 wt%, a decrease in flame retardancy may occur, and when it exceeds 20 wt%, problems with a hard touch and fastness may occur.

[0029] In addition, in the present invention, when the spun yarn to be coated is an aramid spun yarn, it is preferable that the ultraviolet curable coating solution be a mixture of 30 to 40 wt% of an ultraviolet curable oligomer, 21.5 to 40.5 wt% of an ultraviolet curable monomer, 15 to 20 wt% of a commercialized phosphorus oligomer, 12 to 15 wt% of a pigment, and 2.5 to 3.5 wt% of a photoinitiator.

[0030] When the UV-curable oligomer is less than 30 wt%, the coating layer may peel off due to friction caused by a decrease in adhesive strength, and when it exceeds 40 wt%, the viscosity of the UV-curable coating solution may increase, causing problems with coating uniformity, and the denim fabric may have a hard touch due to an increase in the coating thickness. When the UV-curable monomer is less than 21.5 wt%, a problem due to a hard touch after coating may occur, and when it exceeds 40.5 wt%, problems with high color development and friction fastness may occur. When the commercialized phosphorus oligomer is less than 15 wt%, a problem with reduced flame retardancy may occur, and when it exceeds 20 wt%, a problem with a hard touch and fastness may occur.

[0031] In general, most resins used in UV-curable coatings are composed of acrylate-based oligomers and monomers. To maintain coating uniformity and soft touch after coating due to twisting and surface fluffiness of spun yarns, the following monomers and oligomers can be used.

[0032] Among the above UV-curable coating solutions, it is preferable to use at least one of a polyurethane-based oligomer, an epoxy-based oligomer, and a polyester-based oligomer as the UV-curable oligomer to maintain soft touch and high fastness properties.

[0033] Among the above UV-curable coating solutions, it is preferable to use at least one of a furfuryl monomer, a trimethylol monomer, a hydroxyl monomer, and an isobornyl monomer as the UV-curable monomer, so that the UV-curable coating solution can penetrate well into the twist of the spun yarn to form a dyeing structure and maintain dyeing levelness.

[0034] It is preferable to use the above photoinitiator as either a phosphine oxide-based photoinitiator or a hydroxyketone-based photoinitiator to improve the degree of curing by improving the degree of crosslinking of the oligomer and monomer.

[0035] The above commercialized phosphorus oligomer preferably uses phosphorus acrylate or brominated acrylate to improve dispersibility with the ultraviolet-curable coating solution and flame retardancy.

[0036] Among the above UV-curable coating solutions, it is preferable to use UV-curable ink as the pigment. The UV-curable ink is in the form of organic pigment particles of 1 to 10 μm in size pulverized by a binder, so that it is easy to penetrate inside during the dyeing process with the spun yarn, and the pigment to be mixed exists within the cross-linked structure of radical polymerization, so that the problem of pigment detachment due to washing and friction can be improved, thereby improving the friction fastness and uniformity after coating, which is preferable.

[0037] After padding the spun yarn with the UV-curable coating solution prepared in this manner, the spun yarn is passed through a pressing roller with a certain pressure to form a thin film coating layer on the surface of the spun yarn. The pressing roller presses the compound solution on the surface of the fiber yarn to form a coating layer of a certain thickness, and the weaving possibility of the color-coated yarn can be evaluated according to the thickness of the coating layer. The pressing roller part for forming a coating layer of a certain thickness must be made of a flexible material such as rubber or silicone that allows for pressure control.

[0038] Afterwards, while advancing the coated spun yarn in a vertical direction from the surface, ultraviolet rays with a wavelength range of 260 to 395 nm are irradiated to harden the ultraviolet-curable coating solution. It is preferable to use a metal halide lamp in which at least one metal substance of Fe, Ga, and Mg is added to a mercury lamp and an ultraviolet LED capable of irradiating ultraviolet rays with the longest wavelength (395 nm), which can improve productivity by irradiating ultraviolet rays with a longer wavelength than a mercury lamp, so that the coating layer can be cured within several seconds to several minutes. Since the ultraviolet LED can be cured at room temperature (20 to 30°C) when irradiated, it is easy to apply to heat-sensitive fiber materials. In addition, an infrared drying unit can be additionally installed before and after the ultraviolet irradiation process to perform an infrared drying process, which is intended to dry the contained moisture or, when using a water-soluble or water-dispersed solution, to improve the degree of curing through moisture drying.

[0039] The following examples provide non-limiting examples of the high-fastness UV curing coating method of the spun yarn of the present invention.

[0040] [Example 1]

[0041] After mixing the compositions shown in Table 1 to prepare a UV-curable coating solution, cotton spun yarn (30 counts, 2 ply) was passed through the impregnation section containing the UV-curable coating solution, padded, and a certain amount of the coating solution was applied. Then, it was pressed with two pressing rollers at a certain pressure (1 MPa) to form a thin film coating layer, and then the liquid coating solution was hardened through photocuring by irradiating it with UV rays with a wavelength range of 260 to 395 nm in a vertical direction from the ground, and wound in the rewinder section to finish. The processing conditions of the UV yarn coating equipment were a padding pressure (0.2 MPa) and a processing speed of 60 m / min with a 100 W / cm metal halide lamp. The friction fastness of the manufactured coated yarn was measured and evaluated in Table 2, and the test results are shown in Fig. 2. In addition, a photograph of the denim fabric woven with the manufactured yarn is shown in Fig. 5.

[0042] UV-curable resin line operating conditions (Sacoating Lab equipment) Oligomer UV00 / 7101 1) 26% padding pressure 0.2 MPa monomer THFA 2) 31%Line speed60m / minTMPTA 3) 5% photoinitiator TPO4 ) 3% UV power 100W / cm x 1EA Pigment BLUE UV curable ink Red UV curable ink 12% Phosphorus oligomer KA 18% 1) Polyurethane oligomer: UV00, epoxy oligomer: 710 1) Furfuryl monomer: Tetra hydro furfuryl acrylate (THFA) 3) Trimethylol monomer: Trimethylol propane triacrylate (TMPTA) 4) Phosphine oxide photoinitiator: TPO (2,4,6-trimethylbenzoyldiphenyl phosphine oxide)

[0043] Color fastness to rubbing Color fastness to washing Color fastness to light Evaluation method Wet and dry cotton yarn 4-544-54 Color fastness evaluation method: 10 times of rubbing on cotton fabric with a load of 1 kg according to KS K ISO 0650 Color fastness evaluation method: Washing for 30 minutes at 40℃ using ECE detergent Color fastness to light: UVA-340nm Sample exposed to UV for 24 hours

[0044] [Example 2]

[0045] As shown in Table 3, a UV-curable coating solution was prepared by mixing the compositions, and then meta-aramid spun yarn (40 count, 2-ply) was passed through the impregnation section containing the UV-curable coating solution, padded, and a certain amount of the coating solution was applied. Then, it was pressed with a certain pressure (1 MPa) on two pressing rollers to form a thin film coating layer, and then the liquid coating solution was hardened through photocuring by irradiating it with UV rays with a wavelength range of 260 to 395 nm in a vertical direction from the ground, and wound and finished in the rewinder section. The processing conditions of the UV yarn coating equipment were a padding pressure (0.2 MPa) and a processing speed of 10 m / min with a 100 W / cm metal halide lamp. The friction fastness of the manufactured coated yarn was measured and evaluated in Table 4, and the test results are shown in Fig. 4. In addition, a photograph of the denim fabric woven with the manufactured yarn is shown in Fig. 6.

[0046] UV-curable resin line operating conditions (Sacoating Lab equipment) Oligomer UV00 / 7101 1) 34% padding pressure 0.2 MPa monomer THFA 2) 25%Line speed60m / minTMPTA 3) 5% photoinitiator TPO4 )3% UV power 100W / cm x 1EA Pigment BLUE UV curable ink Red UV curable ink 15% Phosphorus oligomer KA 18% 1) Polyurethane oligomer: UV00, epoxy oligomer: 71012) Furfuryl monomer: Tetra hydro furfuryl acrylate (THFA) 3) Trimethylol monomer: Trimethylol propane triacrylate (TMPTA) 4) Phosphine oxide photoinitiator: TPO (2,4,6-trimethylbenzoyldiphenyl phosphine oxide)

[0047] Color fastness to rubbing Color fastness to washing Color fastness to light Evaluation method Wet and dry aramid spun yarn 43-44-54 Color fastness evaluation method: 10 times of rubbing on cotton fabric with a load of 1 kg according to KS K ISO 0650 Color fastness evaluation method: Washing for 30 minutes at 40℃ using ECE detergent Color fastness to light: UVA-340nm Expose the sample to UV for 24 hours

Claims

1. Prepare a UV-curable coating solution by mixing a UV-curable oligomer, a UV-curable monomer, a commercially available phosphorus oligomer, a pigment, and a photoinitiator. After padding the spun yarn with the above UV curable coating solution, After passing through a pressure roller with a constant pressure, a thin film coating layer is formed on the surface of the spun yarn. A method for high-fastness UV curing coating of spun yarn for denim fabric, characterized in that the coated spun yarn is advanced vertically from a surface while being irradiated with ultraviolet rays to cure the ultraviolet curing coating solution.

2. In paragraph 1, A method for high-fastness UV-curable coating of spun yarn for denim fabric, characterized in that the spun yarn is cotton spun yarn, and the UV-curable coating solution is a mixture of 25 to 32 wt% of UV-curable oligomer, 32.5 to 47.5 wt% of UV-curable monomer, 15 to 20 wt% of commercialized phosphorus oligomer, 10 to 12 wt% of pigment, and 2.5 to 3.5 wt% of photoinitiator.

3. In paragraph 1, The above-mentioned spun yarn is an aramid spun yarn, and the UV-curable coating solution is characterized by mixing 30 to 40 wt% of a UV-curable oligomer, 21.5 to 40.5 wt% of a UV-curable monomer, 15 to 20 wt% of a commercialized phosphorus oligomer, 12 to 15 wt% of a pigment, and 2.5 to 3.5 wt% of a photoinitiator. A method for highly fast UV-curable coating of spun yarn for denim fabric.

4. In paragraph 1, A method for high-fastness UV-curable coating of spun yarn for denim fabric, characterized in that the above-mentioned UV-curable oligomer is at least one of a polyurethane-based oligomer, an epoxy-based oligomer, and a polyester-based oligomer.

5. In paragraph 1, A method for high-fastness UV-curing coating of spun yarn for denim fabric, characterized in that it comprises at least one of the above-mentioned UV-curable furfuryl monomer, trimethylol monomer, hydroxyl monomer, and isobornyl monomer.

6. In paragraph 1, A method for high-fastness UV curing coating of spun yarn for denim fabric, characterized in that the photoinitiator is any one of a phosphine oxide-based photoinitiator and a hydroxyketone-based photoinitiator.

7. In paragraph 1, A method for high-fastness UV curing coating of spun yarn for denim fabric, characterized in that the commercialized phosphorus oligomer is a phosphorus acrylate or a brominated acrylate.

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