Core-sheath composite fiber

Abstract

The present application discloses a kind of core sheath composite fibers, the core component of the core sheath composite fiber contains the particle A with refractive index of 1.4 or more, sheath component contains infrared absorbing particle B.The core sheath composite fiber reduces the amount of particle B while improving the utilization of light, achieves excellent heating effect, and improves the color tone, good productivity, can be applied to the field of fabric.

Description

Technical Field

[0001] This invention relates to a core-sheath composite fiber, specifically, to a core-sheath composite fiber in which the core component contains high-refractive-index particles and the sheath component contains infrared-absorbing particles. Background Technology

[0002] As people's living standards improve, the market demand for lightweight and warm winter clothing is growing.

[0003] In existing technologies, physical or chemical modifications are typically used to improve the warmth retention of fabrics. Chinese patent CN101052755A discloses a near-infrared absorbing fiber, the surface and / or interior of which contain tungsten oxide particles and / or composite tungsten oxide particles, the content of which is 0.001% to 80% by weight relative to the fiber's solid composition. While adding a large amount of near-infrared absorbing particles does indeed improve the heating effect, excessive infrared absorbing particles not only worsen fiber productivity but also cause the fiber to become too dark, making it difficult to apply to light-colored fabrics.

[0004] Therefore, it is necessary to reduce the dependence on infrared absorbing particles and design a fiber with low infrared absorbing particle content, excellent heat generation and color tone, and good productivity. Summary of the Invention

[0005] The purpose of this invention is to provide a core-sheath composite fiber with excellent heating effect, good color, and good manufacturability.

[0006] The technical solution of this invention is as follows:

[0007] The core-sheath composite fiber contains particles A with a refractive index of 1.4 or higher in the core component and infrared absorbing particles B in the sheath component.

[0008] The particle B preferably accounts for 0.05 to 50.00 wt% of the sheath composition; the particle B is preferably one or more of composite tungsten oxide, silicon nitride, antimony tin oxide, and indium tin oxide.

[0009] Particle A preferably accounts for 0.01 to 30.00 wt% of the core composition; particle A is preferably one or more of titanium dioxide, zinc oxide, and aluminum oxide.

[0010] The weight ratio of particle B to particle A is preferably 0.010 to 1.000:1.

[0011] This invention combines high-refractive-index particles and infrared-absorbing particles to create composite fibers that simultaneously possess excellent thermal properties and color tone, while also exhibiting superior manufacturability. The resulting fabrics have a warming effect. Detailed Implementation

[0012] Infrared absorbing particles are a type of heat-generating particle that absorbs infrared rays from sunlight and releases heat, thus achieving a heating effect. In current technology, infrared absorbing particles are typically added to enhance the heat-generating properties of fibers, creating warm fabrics. However, when infrared rays strike the fibers, some penetrate and are reflected by the fiber surface. Therefore, the amount of infrared radiation actually absorbed by the infrared absorbing particles is relatively small, resulting in low efficiency. To improve warmth without increasing fabric thickness, the only option is to increase the content of infrared absorbing particles in the fibers. However, this reduces fiber productivity and degrades color tone.

[0013] This invention provides a core-sheath composite fiber that improves heating performance without increasing the content of infrared absorbing particles. The sheath component of the core-sheath composite fiber contains infrared absorbing particles B. Given the same content of infrared absorbing particles B throughout the fiber, the particles B of this invention can be distributed as widely as possible on the fiber surface, maximizing infrared absorption and heat release.

[0014] To meet the most basic heating requirements, the present invention preferably contains at least 0.05 wt% B particles in the sheath component. The higher the B particle content in the sheath component, the better the heating effect of the core-sheath composite fiber. However, since most infrared absorbing particles have a certain color, the color tone of the core-sheath composite fiber will deteriorate when the B particle content is too high. Therefore, the present invention preferably contains at least 50.00 wt% B particles in the sheath component. To further ensure the heating effect and color tone of the core-sheath composite fiber, the B particle content in the sheath component is more preferably 0.05–10.00 wt%, and most preferably 0.10–1.00 wt%.

[0015] This invention does not specifically limit the composition of particle B, as long as it has infrared absorption function. Considering improving the heating effect, color tone, and productivity of the core-sheath composite fiber, one or more of the following are preferred: composite tungsten oxide, antimony tin oxide, indium tin oxide, or silicon nitride that absorbs near-infrared radiation. Among these, cesium tungsten bronze (CsxWO3) is the most preferred composite tungsten oxide with the best infrared absorption function.

[0016] Of course, simply placing infrared-absorbing particles B in the sheath component is not enough to improve the heating effect of the fiber. The core component of the core-sheath composite fiber of this invention contains high-refractive-index particles A. Incoming light undergoes multiple refractions, reflections, and scatterings at the interface between the core component and particles A, thereby increasing the probability of particles B absorbing infrared radiation and improving the heating effect of the core-sheath composite fiber. Simultaneously, by placing particles A and B separately in the core component and sheath component, respectively, the aggregation of particles A and B can be avoided.

[0017] The refractive index of particle A is 1.4 or higher. If the refractive index of particle A is less than 1.4, the incident light cannot undergo multiple refractions and scatterings at the interface between the core component and particle A, thus failing to increase the probability of particle B absorbing infrared radiation. However, if the refractive index of particle A is too high, the reflection of light increases, which will reduce the color development of the fiber after dyeing (especially black). To ensure that as much infrared radiation as possible is absorbed by particle B, the refractive index of particle A is preferably between 1.6 and 3.0.

[0018] To improve the refraction and scattering of light, the content of particle A in the core component is preferably above 0.01 wt%. However, excessive content of particle A will lead to poor spinnability of the fiber, failing to meet mass production requirements. To further balance the heating effect and spinnability of the core-sheath composite fiber, the content of particle A in the core component is preferably 0.01–30.00 wt%, more preferably 0.05–15.00 wt%, and most preferably 0.05–8.00 wt%.

[0019] This invention does not specifically limit the composition of particle A, as long as the refractive index is above 1.4. Considering improving the heating effect of the fiber and ensuring its productivity, it can be titanium dioxide, zinc oxide, aluminum oxide, hydroxyapatite, tricalcium phosphate, calcium carbonate, silicon dioxide, zirconium oxide, nano-kaolin, iron oxide, etc. To better balance the heating effect and productivity of the core-sheath composite fiber, particle A is preferably one or more of titanium dioxide, zinc oxide, aluminum oxide, and iron oxide, and more preferably titanium dioxide.

[0020] Rayleigh scattering caused by atmospheric molecules and atoms mainly occurs in the visible and near-infrared bands; Mie scattering caused by atmospheric particles has an effect from the near-ultraviolet to the infrared bands. When the wavelength enters the infrared band, the effect of Mie scattering exceeds that of Rayleigh scattering. Therefore, increasing Mie scattering is very important for improving the heating effect of core-sheath composite fibers. In order to ensure sufficient scattering of infrared light, the particle size of particle A and the infrared wavelength should be as consistent as possible. When the particle size of particle A is too small, Mie scattering is not obvious and it is difficult to achieve the purpose of refraction and scattering of infrared light; when the particle size of particle A is too large, it will cause problems such as spinning difficulties and frequent fiber breakage. Therefore, the particle size of particle A in this invention is preferably 0.1-20.0 micrometers, more preferably 0.1-10.0 micrometers, and most preferably 0.5-5.0 micrometers. To achieve better refraction and scattering effects, the more particles of 0.5-5.0 micrometers, the better, and preferably the content of particles A of 0.5-5.0 micrometers accounts for more than 80% of the total amount of particles A.

[0021] Furthermore, the heating effect of core-sheath composite fibers is also related to the weight ratio of particle B to particle A. By adjusting this weight ratio, most of the infrared radiation in the incident light is absorbed by particle B, and the amount of infrared radiation absorbed by particle B is close to saturation, thus maximizing the heating effect. With a fixed total content of particles A and B, as the weight ratio of particles B to particles A increases, the content of particle A decreases, reducing the refraction and scattering of infrared radiation, resulting in less infrared radiation reaching particle B, and a downward trend in the heating effect of the core-sheath composite fiber. Simultaneously, an increase in the content of colored particles B also tends to decrease the fiber's color tone. Conversely, as the weight ratio of particles B to particles A decreases and the content of particle A increases, although the refraction and scattering of infrared radiation increases, the heating effect of the core-sheath composite fiber also tends to decrease due to the reduced content of infrared-absorbing particles B. To further improve the heating effect and color tone of the fiber, the weight ratio of particle B to particle A is preferably 0.010 to 1.000:1, more preferably 0.050 to 1.000:1, and most preferably 0.100 to 1.000:1.

[0022] This invention does not impose particular limitations on the fiber-forming polymers of the core and sheath components of the core-sheath composite fiber, but preferably uses resins suitable for melt spinning, i.e., thermoplastic resins. Examples include polyethylene terephthalate (PET), polypropylene terephthalate (PPT), polybutylene terephthalate (PBT), polyamide-6 (PA6), polyamide-66 (PA66), polyamide-610 (PA610), polypropylene (PP), and polyethylene (PE).

[0023] The core-sheath composite fiber described in this invention can be fully drawn yarn FDY or false twisted yarn DTY, etc.

[0024] This invention does not impose any particular limitation on the preparation method of core-sheath composite fibers, which can be obtained by conventional core-sheath composite fiber preparation methods.

[0025] When adding particles B to prepare core-sheath composite fibers, if the particle size is too small, particles B are not easily dispersed uniformly in the fiber and tend to agglomerate, resulting in poor heating effect; if the particle size of particles B is too large, the spinnability deteriorates, the probability of fiber breakage increases, and it cannot meet production requirements. The particle size of particles B in this invention is preferably 0.01–5.00 micrometers, more preferably 0.02–2.00 micrometers, and most preferably 0.02–1.00 micrometers.

[0026] This invention utilizes a core-sheath composite structure, where the core and sheath components work together. Infrared rays, after being refracted and scattered multiple times by particles A in the core component, are absorbed by particles B in the sheath component, reducing transmitted infrared rays. While reducing the amount of particles B, this increases light utilization, enabling the core-sheath composite fiber to achieve a greater heating effect, improving color tone, and offering good manufacturability, making it applicable to the fabric industry.

[0027] The methods for measuring and evaluating the various indicators of this invention are as follows:

[0028] (1) The refractive index of particle A

[0029] First, the cross-sectional area of ​​the core-sheath composite fiber was photographed using a SEM (Hitachi, TM3030). The cross-sectional images were printed on paper, and the cross-sectional area S1 of the core component and the cross-sectional area S2 of the sheath component were calculated using an area meter. The area ratio of the core component to the sheath component was S1 / S2. Based on the above area ratio and the densities of the core and sheath components, the weight ratio X:S (X+S=100) of the core-sheath composite fiber was calculated. The fiber was then subjected to a weight reduction treatment using a 5 g / L NaOH aqueous solution, with the weight reduction rate controlled above S%. Then, the remaining core component was dissolved using the corresponding solvents listed below, and the particles were separated.

[0030] The solvents corresponding to various resin fibers are as follows:

[0031] Polyester fibers (PET, PBT, PPT): hexafluoroisopropanol;

[0032] Polyamide fibers (PA6, PA66): hexafluoroisopropanol;

[0033] Polyolefin fibers (PP, PE): dichloromethane and cyclohexanone.

[0034] The composition was analyzed by elemental analysis using an inductively coupled plasma mass spectrometer (ICP-MS) (Thermo Fisher Scientific, XSeriels II) to determine the types of particles in the composition, and then the refractive index of the particles used was determined by referring to a refractive index table.

[0035] (2) Content of particle A

[0036] According to the core-sheath weight ratio X:S (X+S=100) obtained by test method (1), the fiber is subjected to weight reduction treatment with 5g / L NaOH aqueous solution, and the weight reduction rate is controlled above S%. Fiber containing only core component is obtained. Take about 4g of the fiber, melt it to prepare a sample, and determine the peak intensity of particle A in it by X-ray fluorescence spectrometer (manufacturer: Rigaku, model: ZSXPrimusⅢ+). The spectrum is compared with the spectrum of a standard sample with known particle A content to obtain the content of particle A.

[0037] (3) Content of particle B

[0038] According to the core-sheath weight ratio X:S (X+S=100) obtained by test method (1), the fiber was subjected to weight reduction treatment with 5g / L NaOH aqueous solution, and the weight reduction rate was controlled below S%. This yielded an alkali-reduced liquid containing only sheath components. The alkali-reduced liquid was then concentrated to obtain a sheath polymer. Approximately 4g of this polymer was taken, melted, and used to prepare a sample. The peak intensity of particle B was tested using an X-ray spectrometer (manufacturer: Rigaku, model: ZSXPrimusⅢ+), and compared with the spectrum of a standard sample with a known particle B content to determine the particle B content.

[0039] (4) Heating effect

[0040] Fabric preparation: 84T-36f fiber was used as both warp and weft yarns and woven in a plain weave with a weaving density of 46 warp yarns / inch and 96 weft yarns / inch to obtain a grey fabric. The grey fabric was then smelted for 20 minutes at 80°C in an aqueous solution of sodium carbonate (1 g / L) and surfactant BK-80 (made by Nichika Chemicals), and then dried in a hot air dryer at 60°C for 60 minutes to obtain the smelted fabric.

[0041] Heating effect test: Test environment temperature and humidity: 20℃×65%RH, test light source: halogen lamp, illumination lumens: 14,000 lumens. A 15cm×15cm fabric was placed 50cm directly below the light source, and the temperature sensor was placed at the center of the fabric. The initial temperature was recorded as T0, and the temperature after 15 minutes was recorded as T1. The temperature rise ΔT = T1 - T0. The larger ΔT is, the better the heating effect.

[0042] (5) Spinning properties

[0043] Spinning properties are judged by assessing the breakage and drift of fibers during spinning.

[0044] Broken yarn: If the number of broken yarns is less than 2 within 12 hours during spinning, it is judged as 0; if the number of broken yarns is 3 to 10, it is judged as △; and if the number of broken yarns is more than 10, it is judged as ×.

[0045] Monofilament breakage: If the number of filament breaks is 4 or less within 12 hours during spinning, it is judged as 0; if the number of filament breaks is 5 to 10, it is judged as △; and if the number of filament breaks is more than 11, it is judged as ×.

[0046] When both the broken filament and floating monofilament are judged as 0, the spinning property is judged as 0; when both are judged as ×, the spinning property is judged as ×; when all other cases besides 0 and × occur, the spinning property is judged as △.

[0047] (6) Hue

[0048] The hue Lab value (L value) of the fabric obtained according to test method (4) was determined using an INTEC SC-T colorimeter. The higher the L value, the better the hue of the fiber.

[0049] (7) Coloration

[0050] The fabric obtained according to test method (4) was heat-set at 160℃ for 2 minutes. After dry heat setting, the fabric was dyed for 60 minutes in a dyeing solution containing 5.0 wt% disperse dye DK9Z3 (black), with the pH adjusted to 5.0, at a liquor ratio of 1:100 and a dyeing temperature of 130℃. Then, the hue Lab value (L value) of the dyed fabric was tested using an INTEC SC-T colorimeter. The lower the L value, the better the color development of the fiber.

[0051] (8) Particle size of particle A

[0052] According to the core polymer obtained by test method (2), the core polymer is dissolved by selecting an appropriate solvent to separate the particles, and the median particle size D50 of particle A is tested using a dynamic light scattering tester (McClone, S3500).

[0053] The advantages of the present invention will now be described in detail through the listed embodiments and comparative examples. The present invention is not limited to the embodiments described below.

[0054] Example 1

[0055] Polyethylene terephthalate (PET) resin containing 0.30 wt% silica was used as the core component, and polyethylene terephthalate (PET) resin containing 0.20 wt% cesium tungsten bronze (CsxWO3) was used as the sheath component. The core and sheath components were pre-crystallized and dried to a moisture content below 50 ppm. The core-to-sheath composite ratio was controlled at 50:50. The fibers were fed into spinning bins A and B respectively for spinning and false twisting to obtain core-sheath composite fibers. The specific formulation and physical properties are shown in Table 1.

[0056] Examples 2-25

[0057] The preparation method is the same as in Example 1, except that the types, contents and core-sheath components of particles A and B are changed. The specific formula and physical properties are shown in Tables 1 to 3.

[0058] Comparative Example 1

[0059] Particle A was not added to the core component; otherwise, it was the same as in Example 4. The specific formulation and properties are shown in Table 3.

[0060] Because high-refractive-index particles A were not added, the resulting core-sheath composite fiber had a low ΔT and poor heating performance.

[0061] Comparative Example 2

[0062] Particle A was transformed into nano-crystals with a refractive index of 1.2, and the rest remained the same as in Example 4. The specific formulation and properties are shown in Table 3.

[0063] Because particle A has a low refractive index, the resulting core-sheath composite fiber has a low ΔT and poor heating effect.

[0064] Comparative Example 3

[0065] Polyethylene terephthalate (PET) chips containing 0.15 wt% titanium dioxide and 0.10 wt% cesium tungsten bronze were pre-crystallized and dried to a moisture content below 50 ppm. These chips were then fed into a spinning hopper for spinning and false twisting to obtain single-component fibers. Specific formulations and properties are shown in Table 3.

[0066] Because particle B failed to disperse sufficiently on the fiber surface, it could not fully absorb infrared radiation, resulting in a low ΔT and poor heating performance in the fiber.

[0067]

[0068]

[0069]

Claims

1. Core-sheath composite fiber, characterized by: The core component of the core-sheath composite fiber contains particles A with a refractive index of 1.4 or higher, and the sheath component contains infrared absorbing particles B.

2. The core-sheath composite fiber according to claim 1, characterized in that: The particle B accounts for 0.05 to 50.00 wt% of the sheath composition.

3. The core-sheath composite fiber according to claim 1 or 2, characterized in that: Particle A accounts for 0.01 to 30.00 wt% of the core composition.

4. The core-sheath composite fiber according to claim 1 or 2, characterized in that: The weight ratio of particle B to particle A is 0.010 to 1.000:

1.

5. The core-sheath composite fiber according to claim 1 or 2, characterized in that: The particle B is one or more of the following: composite tungsten oxide, silicon nitride, antimony tin oxide, and indium tin oxide.

6. The core-sheath composite fiber according to claim 1, characterized in that: Particle A is one or more of titanium dioxide, zinc oxide, aluminum oxide, and iron oxide.

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