Anti-see-through polyester composite fiber

Abstract

An anti-see-through polyester composite fiber, which mainly consists of a core component polyester A and a sheath component polyester B, wherein the content of inorganic particles in the polyester A is greater than that of inorganic particles in the polyester B; the polyester A mainly consists of a terephthalic acid structural unit, an aliphatic diol structural unit and an isophthalic acid structural unit, the isophthalic acid structural unit accounting for 0.5-3.0 wt% of the polyester A; and the composite fiber contains inorganic particles that account for 5-20 wt% of the composite fiber. The composite fiber has a high inorganic particle content and a good anti-see-through property; moreover, both the colorability of the fiber and the dispersity of the inorganic particles can be improved; and a spinning assembly used in a spinning process has long service life, yarn breakage hardly occurs, and the cost is low.

Description

Anti-permeability polyester composite fiber Technical Field

[0001] The present invention relates to an anti-seepage polyester composite fiber, in particular to a polyester composite fiber with high inorganic particle content and good dispersibility. Background Art

[0002] Polyester fiber, due to its excellent mechanical properties and chemical resistance, is widely used in clothing applications. For fibers used in clothing, comfort and concealment are fundamental requirements. Currently, commercially available anti-see-through fabrics often utilize the light-blocking effect of inorganic particles, achieved by adding appropriate amounts of these particles to the fiber. For example, the most common fully matte fiber is made by adding 2-3wt% titanium dioxide particles to the fiber.

[0003] However, as people's demands for a comfortable wearing experience continue to rise, and in the pursuit of lighter, more comfortable fabrics, anti-see-through properties are becoming increasingly important. The anti-see-through properties of conventional fully matte fibers are increasingly failing to meet these demands. Chinese patent CN105155009A discloses an orange-peel anti-see-through fiber, a non-peeling orange-peel-shaped, two-component composite fiber composed of a polymer and the polymer containing 5-16 wt% TiO2. The opacity of the orange-peel anti-see-through fiber reaches 99% to 100%. However, due to the high particle content in the polymer containing 5-16 wt% TiO2, the particles are more likely to agglomerate within the polymer to form coarse particles. These coarse particles cannot pass through the spinning filter during spinning, shortening the life of the spinning assembly. Furthermore, coarse particles can cause yarn breakage, reducing fiber yield and impacting spinning efficiency and cost. Furthermore, fibers with a high inorganic particle content cannot be dyed darker, limiting the fiber's range of applications.

[0004] Chinese patent CN113026142A discloses a core-sheath composite fiber composed of a core component comprising an ultra-matte polyester containing 5-15% by weight titanium dioxide, and a sheath component comprising a functional copolyester easily dyed with disperse dyes. This core-sheath composite polyester fiber exhibits high color development. While this patent addresses the issue of fibers with high inorganic particle content not being able to achieve deep dyeing, it still presents challenges such as particle agglomeration caused by the large amount of inorganic particles added, resulting in a short lifespan of the spinning assembly, frequent yarn breakage, and high costs. Summary of the Invention

[0005] The present invention aims to provide a polyester composite fiber with a high inorganic particle content, excellent barrier properties, and improved fiber color development and inorganic particle dispersion. The spinning assembly used in the spinning process of the composite fiber has a long lifespan, minimal fiber breakage, and low cost.

[0006] The technical solution of the present invention is:

[0007] The barrier polyester composite fiber is mainly composed of a core component polyester A and a sheath component polyester B, wherein the inorganic particle content of polyester A is greater than that of polyester B. The polyester A is mainly composed of terephthalic acid structural units, aliphatic diol structural units, and isophthalic acid structural units, and the isophthalic acid structural units account for 0.5-3.0wt% of the polyester A. The composite fiber contains 5-20wt% of the inorganic particles.

[0008] The content of inorganic particles in the polyester A is preferably 6.5 to 40.0 wt%.

[0009] The polyester B is preferably one or more of polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, cationically modified polyethylene terephthalate, cationically modified polypropylene terephthalate or cationically modified polybutylene terephthalate.

[0010] The thickness of the sheath component of the composite fiber is preferably 0.2 to 2.0 microns.

[0011] The content of inorganic particles in the polyester B is preferably 0 to 0.5 wt%.

[0012] The inorganic particles are preferably one or more of titanium dioxide, silicon dioxide, barium sulfate and magnesium oxide.

[0013] The inorganic particles are preferably a mixture of silicon dioxide and titanium dioxide, and the weight ratio of silicon dioxide to titanium dioxide is preferably 1:10-500.

[0014] The composite fiber preferably has a penetration barrier rate of 93 to 99%.

[0015] The L value of the composite fiber is preferably 90 to 97, and the b value is preferably -4 to 6; the L value of the composite fiber after dark black dyeing is preferably 13 to 16.

[0016] The core component of the core-sheath composite fiber disclosed in the present invention contains a high content of inorganic particles, and the core component polymer is polyester A copolymerized with isophthalic acid. The steric hindrance generated by the embedding of isophthalic acid in polyester A can expand the gaps between molecules, improve molecular activity, and provide more dispersion power and dispersion space for inorganic particles, thereby solving the problem that high-content inorganic particles are difficult to disperse in polymers, thereby extending the service life of the spinning assembly, improving yarn breakage, reducing costs, and obtaining a highly transparent composite fiber that can be deeply dyed. DETAILED DESCRIPTION

[0017] The anti-permeability polyester composite fiber of the present invention is mainly composed of a core component polyester A and a sheath component polyester B, and the content of inorganic particles in the polyester A is greater than that in the polyester B.

[0018] In order to achieve excellent anti-permeability effect, the content of inorganic particles in the composite fiber is equivalent to 5 to 20wt% of the total amount of the composite fiber. When the content of inorganic particles in the composite fiber is lower than 5wt%, the composite fiber does not have good anti-permeability. When the content of inorganic particles in the composite fiber is higher than 20wt%, since the inorganic particles are not ductile, adding a large amount will cause the strength and elongation of the fiber to decrease, and it will not meet the standards for clothing use; and the more inorganic particles there are, the more difficult it will be to disperse in polyester, which will cause the inorganic particles to agglomerate to form coarse particles, which will be difficult to pass through the spinning component filter, causing the component filter pressure to rise too quickly, shortening the component replacement cycle, and increasing labor and material costs; at the same time, the increase in coarse particles will also cause an increase in broken silk during the spinning production process, resulting in waste of raw materials, reduced quality of fiber products, and increased costs.

[0019] Exposing too many inorganic particles on the fiber surface increases the likelihood of them falling off. Furthermore, due to their high hardness, friction between them and rollers, yarn guides, and other components during spinning can increase equipment wear. Therefore, the inorganic particles in the composite fiber described herein are primarily present in polyester A. Improving the dispersibility of the inorganic particles in polyester A can reduce agglomeration caused by high levels of inorganic particles.

[0020] The method for improving the dispersibility of inorganic particles in polyester A is to copolymerize isophthalic acid in polyester A, wherein the isophthalic acid structural units account for 0.5 to 3.0 wt.% of polyester A. By introducing isophthalic acid structural units into polyester A, the regularity of the polyester molecular chains is disrupted to a certain extent, the crystallinity of the polyester is reduced, and the spaces between the polyester molecular chains are increased, thereby facilitating the dispersion and movement of inorganic particles in polyester A. This can effectively alleviate the problem of difficulty in dispersing and easy agglomeration of large amounts of inorganic particles added to polyester.

[0021] The addition of large amounts of inorganic particles that block visible light can lead to poor fiber dark dyeing and a high L value after rich black dyeing. The isophthalic acid structural units contained in the polyester A of the present invention can reduce the regularity of the polyester A molecular chain and inhibit crystallization, allowing dye molecules to more easily enter the polyester A molecules, increasing dye uptake, thereby improving color development and reducing the L value. Within a certain range, increasing the content of isophthalic acid structural units tends to reduce the L value of the fiber after rich black dyeing.

[0022] If the content of the isophthalic acid structural units in the polyester A is less than 0.5 wt%, the dispersion of the inorganic particles in the polyester A cannot be improved, nor can the crystallization of the polyester A be effectively suppressed to improve the dark dyeing problem of the fiber. If the content of the isophthalic acid structural units in the polyester A is greater than 3.0 wt%, the isophthalic acid structural units will significantly disrupt the regularity of the polyester A molecular chain and reduce crystallization performance, resulting in reduced strength of the composite fiber, increased boiling water shrinkage, and poor dimensional stability of the fiber, thus affecting the use of fiber products. The polyester A of the present invention preferably contains 1.0 to 2.5 wt% of the isophthalic acid structural units.

[0023] The inorganic particle content of the polyester A is preferably 6.5 to 40.0 wt%. If the inorganic particle content of the polyester A is too low, the inorganic particle content in the composite fiber cannot reach 5 wt%, resulting in poor barrier properties. If the inorganic particle content of the polyester A is too high, the isophthalic acid structural units in the polyester A do not provide sufficient space for the inorganic particles to disperse, and the inorganic particles tend to agglomerate and form coarse particles. More preferably, the inorganic particle content of the polyester A is 10.0 to 25.0 wt%.

[0024] The composition of the polyester B is not particularly limited in the present invention. From the perspectives of fiber formation and fabric use, polyethylene terephthalate, polypropylene terephthalate, or polybutylene terephthalate are preferred. From the perspective of dyeability, cationically modified polyethylene terephthalate, cationically modified polypropylene terephthalate, or cationically modified polybutylene terephthalate are preferred. The aforementioned polyesters may be used alone or in combination.

[0025] The polyester B may or may not contain inorganic particles. In the case of polyester B containing inorganic particles, the content should be limited. This is because excessive exposure of the inorganic particles on the fiber surface can increase the likelihood of particle shedding. Furthermore, the inorganic particles are relatively hard, and friction with rollers, yarn guides, and other components during spinning can increase equipment wear. Therefore, the present invention preferably contains 0 to 0.5 wt% inorganic particles in the polyester B.

[0026] The thickness of the sheath component is preferably 0.2 to 2.0 microns. If the sheath component is too thin, it cannot completely cover the polyester A, which will cause the polyester A with a high content of inorganic particles to be exposed, resulting in equipment wear, broken fibers, low fiber performance, and inorganic particle shedding. If the sheath component is too thick, light will pass through the polyester B layer with a low inorganic particle content, causing the fiber's barrier properties to decrease.

[0027] The inorganic particles can be one or more of titanium dioxide, silicon dioxide, barium sulfate, zinc oxide, boron nitride, calcium carbonate, magnesium oxide, magnesium carbonate, and magnesium acetate. Based on light transmittance and their effect on spinning, the inorganic particles are preferably one or more of titanium dioxide, silicon dioxide, barium sulfate, and magnesium oxide. The inorganic particles in polyester A and polyester B can be the same compound or mixture, or different compounds or mixtures. To achieve a higher barrier effect, the inorganic particles are more preferably a mixture of titanium dioxide and magnesium oxide.

[0028] To achieve composite fibers with improved barrier properties, color tone, and inorganic particle dispersion, the inorganic particles in the polyester A described herein are most preferably a mixture of silica and titanium dioxide. This is because titanium dioxide has extremely excellent light-shielding properties, ensuring the fiber's barrier properties. Silica, on the other hand, has excellent dye absorption properties, improving dyeability and mitigating the problem of intense dyeing caused by high inorganic particle content. Furthermore, a certain amount of silica doped with titanium dioxide can hinder adsorption between titanium dioxide particles, reducing titanium dioxide agglomeration, thereby improving spinning filtration and extending assembly cycles. The weight ratio of silica to titanium dioxide is preferably 1:10 to 500.

[0029] The composite fiber of the present invention has excellent anti-permeability effect, with an anti-permeability rate of 93-99%. At the same time, due to the good dispersibility of the inorganic particles and the absence of agglomeration, the composite fiber has a good color tone after dyeing, with an L value of 90-97, a b value of -4-6, and an L value of 13-16 after dark black dyeing.

[0030] The anti-permeability composite polyester fiber of the present invention can be used for preparing textiles, and the obtained textiles have high anti-permeability performance.

[0031] The test methods for the various parameters involved in the present invention are as follows:

[0032] (1) Content of phthalic acid structural units in polyester A

[0033] First, the fiber was placed in hot water containing an alkaline solution for weight reduction. The fiber cross-section was then observed under an optical microscope to ensure that the polyester B in the fiber sheath was completely dissolved. Hydrogen ion magnetic resonance spectroscopy was then used to measure the isophthalic acid content in the polyester A. The final result was the average of five tests.

[0034] (2) Inorganic particle content in fiber

[0035] About 4 g of the fiber was melted to prepare a sample, and the inorganic particle content was measured using an X-ray fluorescence spectrometer (manufacturer: Rigaku, model: ZSX Primus III+). The final result was the average of 5 tests.

[0036] (3) Inorganic particle content of polyester A layer

[0037] The fiber was first placed in a hot alkaline solution for weight reduction. The fiber cross-section was then observed under an optical microscope to ensure complete dissolution of the polyester B in the fiber sheath. Approximately 4 g of this dissolved fiber was melted and sampled. The inorganic particle content was determined using an X-ray fluorescence spectrometer (manufacturer: Rigaku, model: ZSX Primus III+). The final result was the average of five tests.

[0038] (4) Inorganic particle content of polyester B layer

[0039] First, the fiber is placed in hot water of an alkaline solution for weight reduction. The fiber cross-section is then observed under an optical microscope to ensure that the polyester B layer of the fiber sheath is partially dissolved (the polyester B layer also covers the polyester A layer). The weight reduction rate N is measured. About 4g of the dissolved fiber is melted and sampled. The inorganic particle content M1 is measured using an X-ray fluorescence spectrometer (manufacturer: Rigaku, model: ZSX PrimusⅢ+). The inorganic particle content M of the polyester B layer can then be calculated. B . M B ={[M0-M1×(1-N)] / N}×100%,

[0040] Where M0 is the inorganic particle content of the composite fiber before weight reduction. The final result is the average value after 5 tests.

[0041] (5) Ratio of inorganic particles in polyester A

[0042] The fiber was first placed in hot water containing an alkaline solution for weight reduction. The fiber cross-section was then observed under an optical microscope to ensure complete dissolution of the polyester B in the fiber sheath. Approximately 4g of this dissolved fiber was then melted and sampled. The inorganic particle content of the remaining polyester A component after weight reduction was measured using an X-ray fluorescence spectrometer (manufacturer: Rigaku, model: ZSX Primus III+). The ratio of the various inorganic particle contents was then determined. The final result was the average of five tests.

[0043] (6) Fiber sheath thickness

[0044] Cut a fiber cross section and measure the fiber sheath thickness directly under an electron microscope. The final result is the average of 5 tests.

[0045] (7) Anti-transmission rate

[0046] The fiber is made into a plain weave fabric with a cover factor of 1800 to 2200. Use a colorimeter to test the L value of a white board and a black board: L (white) and L (black). Take a fabric sample (10×10cm) and test the L value against a white board and a black board: L (white + cloth) and L (black + cloth).

[0047] Anti-transmission rate: (1-(L(white+cloth)-L(black+cloth)) / (L(white)-L(black))×100%.

[0048] The final result is the average value of 5 tests.

[0049] (8) Fiber hue

[0050] The fibers were made into a plain weave fabric with a cover factor of 1800-2200. The fabric was scoured in 80°C hot water with a scouring agent (2g / L) for 20 minutes, followed by drying. The fabric's L and b values ​​were measured using a colorimeter. The final result was the average of five tests.

[0051] (9) Fiber color after dark dyeing

[0052] The fibers were made into a plain weave fabric with a cover factor of 1800-2200. 2g / L of refining agent was added to 80°C hot water, scoured for 20 minutes, and then dried. Dyeing was performed using a liquid flow infrared dyeing machine under the following conditions: ① Dye: 8wt% disperse black (relative to the mass of the plain weave fabric), ② Liquor ratio: 1:20, ③ Dyeing temperature: 130°C, and ④ Dyeing time: 45 minutes. After dyeing, the fabric was soaped under the following conditions: ① Hydrosulfite: 1g / L (relative to the concentration of the soaping solution), ② Sodium hydroxide: 0.6g / L (relative to the concentration of the soaping solution), ③ Liquor ratio: 1:20, ④ Soaping temperature: 80°C, and ⑤ Soaping time: 20 minutes. After soaping, the fabric was dried and set at 180°C for 1 minute. The L value of the dark black dyed plain weave fabric was measured using a color tint meter. The final result was the average of five tests.

[0053] (10) Fiber strength-elongation product

[0054] According to the standard GB / T14344-2008, the strength and elongation of the fiber are tested respectively, and the strength-elongation product of the fiber is calculated using the formula: Strength-elongation product = strength × (elongation) 1 / 2 The final result is the average value of 5 tests.

[0055] When the value of the strength-elongation product of the fiber is greater than 18, it is judged as ◎; when the value of the strength-elongation product of the fiber is 13-18, it is judged as ○; when the value of the strength-elongation product of the fiber is 11-13 (excluding 13), it is judged as △; when the value of the strength-elongation product of the fiber is less than 11, it is judged as ×.

[0056] (11) Fiber boiling water shrinkage

[0057] The boiling water shrinkage of the fiber was tested according to JIS L 1013:2021, 8.18. The final result was the average of five tests. A boiling water shrinkage of 3% to 8% was rated as ○, 8% to 11% (excluding 8) was rated as △, and a boiling water shrinkage greater than 11% was rated as ×. Lower boiling water shrinkage indicates better dimensional stability of the fiber.

[0058] (12) Spinning assembly cycle

[0059] Since a large amount of inorganic particles are added to polyester A, a large amount of inorganic particles will agglomerate and cause poor filterability. The pressure of the spinning assembly rises too quickly, and when the assembly pressure rises to 25MPa, it reaches the safety limit that the spinning equipment can withstand, and the assembly needs to be replaced. Therefore, the replacement cycle of the spinning assembly in the present invention depends on the increase in the spinning pressure on the polyester A side. In addition, the spinning assembly cycle is not only related to the filterability of polyester, but also affected by the filter mesh size, filter area and spinning variety of the spinning assembly. For the convenience of explanation, the present invention will make limitations on the above and give examples to illustrate. However, the scope of the present invention should not be limited by this example. The present invention uses the filter mesh specification of the polyester A component in the spinning assembly as 800 mesh and the filter mesh area as 19.6cm 2 The spinning variety is 100T-36-POY. Under these filter and inorganic particle flow rate conditions (the amount of inorganic particles in the polyester discharged per unit area when passing through the filter), a module cycle greater than 15 days is evaluated as ◎; a module cycle of 8 to 15 days is evaluated as ○; a module cycle of 6 to 8 days (excluding 8 days) is evaluated as △; and a module cycle of less than 6 days is evaluated as ×.

[0060] (13) Spinnability

[0061] The number of yarn breaks during spinning is used to characterize spinnability. Spinnability is also affected by the fiber thickness and type. For ease of illustration, the present invention uses the spinning variety 100T-36-POY for testing. Based on fiber yield, if the number of yarn breaks is 0-0.6 / ton, the spinnability is judged as ○; if the number of yarn breaks is 0.6-1.5 / ton (excluding 0.6), the spinnability is judged as △; if the number of yarn breaks is greater than 1.5 / ton (excluding 1.5), the spinnability is judged as ×.

[0062] The present invention will be described in detail below with reference to the embodiments.

[0063] Example 1

[0064] 70 parts by weight of a polyethylene terephthalate (PET) copolymer (core component, polyester A) containing 1.5%wt isophthalic acid units and 17.0wt% TiO2 particles, and 30 parts by weight of a semi-dull polyester (sheath component, polyester B) containing 0.3wt% TiO2 particles were pre-crystallized and dried to below 50ppm, respectively, and placed in spinning silos A and B. The spinning process was carried out using a core-sheath composite structure. The spinning variety was 100T-36-POY, the assembly cycle was 11 days, and the number of broken yarns was 0.4 times / T. The resulting POY was false-twisted to produce a barrier composite fiber. The resulting fiber had a TiO2 content of 12.0wt%, a sheath thickness of 1.0μm, a fiber strength-elongation product of 15.9, and a boiling water shrinkage of 5.9%. The resulting fiber was made into a fabric with a cover factor of 2000, and the barrier rate of the fabric was measured to be 96%. The hue values ​​of the resulting fabric after dyeing are shown in Table 1.

[0065] Example 2

[0066] 70 parts by weight of a polyethylene terephthalate (PET) copolymer (core component, polyester A) containing 0.5%wt isophthalic acid units and 17.0wt% TiO2 particles, and 30 parts by weight of a semi-dull polyester (sheath component, polyester B) containing 0.3wt% TiO2 particles were pre-crystallized and dried to below 50ppm, respectively, and placed in spinning silos A and B. Spinning was carried out in a core-sheath composite form. The spinning variety was 100T-36-POY, the assembly cycle was 7 days, and the number of broken yarns was 0.2 times / T. The obtained POY was false-twisted to produce a barrier composite fiber. The obtained fiber had a TiO2 content of 12.0wt%, a sheath thickness of 1.0μm, a fiber strength-elongation product of 16.5, and a boiling water shrinkage of 4.4%. The obtained fiber was made into a fabric with a cover factor of 2000, and the barrier rate of the fabric was measured to be 96%. The hue value of the obtained fabric after dyeing is shown in Table 1.

[0067] Example 3

[0068] 70 parts by weight of a polyethylene terephthalate (PET) copolymer (core component, polyester A) containing 3.0%wt isophthalic acid units and 17.0wt% TiO particles, and 30 parts by weight of a semi-dull polyester (sheath component, polyester B) containing 0.3wt% TiO particles were pre-crystallized and dried to below 50ppm. The mixture was then placed in spinning silos A and B, respectively, and spun in a core-sheath composite format. The spinning product was 100T-36-POY, the assembly cycle was 16 days, and the number of broken yarns was 0.9 per ton. The resulting POY was false-twisted to produce a barrier composite fiber. The resulting fiber had a TiO content of 12.0wt%, a sheath thickness of 1.0μm, a fiber strength-elongation product of 11.4, and a boiling water shrinkage of 9.7%. The resulting fiber was made into a fabric with a cover factor of 2000, and the barrier efficiency of the fabric was measured to be 96%. The raw ground and color tone values ​​of the resulting fabric after dyeing are shown in Table 1.

[0069] Example 4

[0070] 80 parts by weight of a polyethylene terephthalate (PET) copolymer (core component, polyester A) containing 1.5%wt isophthalic acid units and 5.0wt% TiO2 particles, and 20 parts by weight of a semi-dull polyester (sheath component, polyester B) containing 0.3wt% TiO2 particles were pre-crystallized and dried to below 50ppm, respectively, and placed in spinning silos A and B. Spinning was carried out in a core-sheath composite form. The spinning variety was 100T-36-POY, the assembly cycle was 17 days, and the number of broken yarns was 0.2 times / T. The resulting POY was false-twisted to produce a barrier composite fiber. The resulting fiber had a TiO2 content of 4.1wt%, a sheath thickness of 0.7μm, a fiber strength-elongation product of 17.8, and a boiling water shrinkage of 4.7%. The resulting fiber was made into a fabric with a cover factor of 2000, and the barrier rate of the fabric was measured to be 90%. The hue values ​​of the resulting fabric after dyeing are shown in Table 1.

[0071] Example 5

[0072] 80 parts by weight of a polyethylene terephthalate (PET) copolymer (core component, polyester A) containing 1.5%wt isophthalic acid units and 6.5wt% TiO2 particles, and 20 parts by weight of a semi-dull polyester (sheath component, polyester B) containing 0.3wt% TiO2 particles were pre-crystallized and dried to below 50ppm, respectively, and placed in spinning silos A and B. Spinning was carried out in a core-sheath composite form. The spinning variety was 100T-36-POY, the assembly cycle was 14 days, and the number of broken yarns was 0.3 times / T. The obtained POY was false-twisted to obtain an anti-penetration composite fiber. The obtained fiber had a TiO2 content of 5.3wt%, a sheath thickness of 0.7μm, a fiber strength-elongation product of 17.5, and a boiling water shrinkage of 5.5%. The obtained fiber was made into a fabric with a cover factor of 2000, and the anti-penetration rate of the fabric was measured to be 93%. The hue value of the obtained fabric after dyeing is shown in Table 1.

[0073] Example 6

[0074] 80 parts by weight of a polyethylene terephthalate (PET) copolymer (core component, polyester A) containing 1.5%wt isophthalic acid units and 25.0wt% TiO2 particles and 80 parts by weight of a semi-dull polyester (sheath component, polyester B) containing 0.3wt% TiO2 particles were pre-crystallized and dried to below 50ppm, respectively, and placed in spinning silos A and B. Spinning was carried out in a core-sheath composite form. The spinning variety was 100T-36-POY, the assembly cycle was 11 days, and the number of broken yarns was 0.8 times / T. The obtained POY was false-twisted to obtain an anti-penetration composite fiber. The obtained fiber had a TiO2 content of 20.1wt%, a sheath thickness of 0.7μm, a fiber strength-elongation product of 12.9, and a boiling water shrinkage of 5.8%. The obtained fiber was made into a fabric with a cover factor of 2000, and the anti-penetration rate of the fabric was measured to be 99%. The hue value of the obtained fabric after dyeing is shown in Table 1.

[0075] Example 7

[0076] 70 parts by weight of a polyethylene terephthalate (PET) copolymer containing 1.5% by weight isophthalic acid units and 17.0% by weight TiO2 particles (core component, polyester A) and 30 parts by weight of a high-gloss polyester (sheath component, polyester B) free of inorganic particles were pre-crystallized and dried to below 50 ppm. The fibers were then placed in spinning silos A and B, respectively, and spun in a core-sheath composite format. The spinning product was 100T-36-POY, with an assembly cycle of 11 days and 0.3 yarn breakages per ton. The resulting POY was false-twisted to produce a barrier composite fiber. The resulting fiber had a TiO2 content of 11.9% by weight, a sheath thickness of 1.0 μm, a fiber strength-elongation product of 15.4, and a boiling water shrinkage of 5.6%. The resulting fiber was made into a fabric with a cover factor of 2000, and the barrier efficiency of the fabric was measured to be 95%. The hue values ​​of the resulting fabric after dyeing are shown in Table 1.

[0077] Example 8

[0078] 70 parts by weight of a polyethylene terephthalate (PET) copolymer (core component, polyester A) containing 1.5%wt isophthalic acid units and 17.0%wt TiO2 particles, and 30 parts by weight of a cationic polyester (sheath component, polyester B) containing 0.07%wt TiO2 particles were pre-crystallized and dried to below 50ppm. The mixture was then placed in spinning silos A and B, respectively, and spun using a core-sheath composite. The spinning product was 100T-36-POY, with an assembly cycle of 11 days and 0.4 yarn breakages per ton. The resulting POY was false-twisted to produce a barrier composite fiber. The resulting fiber had a TiO2 content of 11.9wt%, a sheath thickness of 1.0μm, a fiber strength-elongation product of 14.5, and a boiling water shrinkage of 4.9%. The resulting fiber was made into a fabric with a cover factor of 2000, and the barrier efficiency of the fabric was measured to be 96%. The hue values ​​of the resulting fabric after dyeing are shown in Table 1.

[0079] Example 9

[0080] 70 parts by weight of a polyethylene terephthalate (PET) copolymer (core component, polyester A) containing 1.5%wt isophthalic acid units and 17.0wt% TiO2 particles, and 30 parts by weight of a semi-dull polyester (sheath component, polyester B) containing 0.5wt% TiO2 particles were pre-crystallized and dried to below 50ppm, respectively, and placed in spinning silos A and B. Spinning was carried out in a core-sheath composite form. The spinning variety was 100T-36-POY, the assembly cycle was 11 days, and the number of broken yarns was 0.8 times / T. The resulting POY was false-twisted to produce a barrier composite fiber. The resulting fiber had a TiO2 content of 12.1wt%, a sheath thickness of 1.0μm, a fiber strength-elongation product of 14.5, and a boiling water shrinkage of 5.8%. The resulting fiber was made into a fabric with a cover factor of 2000, and the barrier rate of the fabric was measured to be 96%. The hue values ​​of the resulting fabric after dyeing are shown in Table 1.

[0081] Example 10

[0082] 70 parts by weight of a polyethylene terephthalate (PET) copolymer (core component, polyester A) containing 1.5%wt isophthalic acid units and 17.0wt% TiO2 particles, and 30 parts by weight of a fully matte polyester (sheath component, polyester B) containing 2.5wt% TiO2 particles were pre-crystallized and dried to below 50ppm. The mixture was then placed in spinning silos A and B, respectively, and spun using a core-sheath composite. The spinning product was 100T-36-POY, with a 10-day assembly cycle and 1.0 yarn breakages per ton. The resulting POY was false-twisted to produce a barrier composite fiber. The resulting fiber had a TiO2 content of 12.7wt%, a sheath thickness of 1.0μm, a fiber strength-elongation product of 12.2, and a boiling water shrinkage of 4.8%. The resulting fiber was made into a fabric with a cover factor of 2000, and the barrier efficiency of the fabric was measured to be 97%. The hue values ​​of the resulting fabric after dyeing are shown in Table 1.

[0083] Example 11

[0084] 70 parts by weight of a polyethylene terephthalate (PET) copolymer (core component, polyester A) containing 1.5%wt isophthalic acid units and 40.0wt% TiO2 particles, and 30 parts by weight of a semi-dull polyester (sheath component, polyester B) containing 0.3wt% TiO2 particles were pre-crystallized and dried to below 50ppm, respectively, and placed in spinning silos A and B. The spinning process was carried out using a core-sheath composite structure. The spinning variety was 100T-36-POY, the assembly cycle was 6 days, and the number of broken yarns was 1.0 times / T. The resulting POY was false-twisted to produce a barrier composite fiber. The resulting fiber had a TiO2 content of 28.1wt%, a sheath thickness of 1.0μm, a fiber strength-elongation product of 11.2, and a boiling water shrinkage of 4.4%. The resulting fiber was made into a fabric with a cover factor of 2000, and the barrier rate of the fabric was measured to be 99%. The hue values ​​of the resulting fabric after dyeing are shown in Table 2.

[0085] Example 12

[0086] 70 parts by weight of a polyethylene terephthalate (PET) copolymer (core component, polyester A) containing 1.5%wt isophthalic acid units and 45.0wt% TiO2 particles, and 30 parts by weight of a semi-dull polyester (sheath component, polyester B) containing 0.3wt% TiO2 particles were pre-crystallized and dried to below 50ppm, respectively, and placed in spinning silos A and B. The spinning process was carried out using a core-sheath composite structure. The spinning variety was 100T-36-POY, the assembly cycle was 6 days, and the number of broken yarns was 1.0 times / T. The resulting POY was false-twisted to produce a barrier composite fiber. The resulting fiber had a TiO2 content of 31.6wt%, a sheath thickness of 1.0μm, a fiber strength-elongation product of 11.0, and a boiling water shrinkage of 4.5%. The resulting fiber was made into a fabric with a cover factor of 2000, and the barrier efficiency of the fabric was measured to be 99%. The hue values ​​of the resulting fabric after dyeing are shown in Table 2.

[0087] Example 13

[0088] 40 parts by weight of a polyethylene terephthalate (PET) copolymer (core component, polyester A) containing 1.5%wt isophthalic acid units and 17.0wt% TiO2 particles, and 60 parts by weight of a semi-dull polyester (sheath component, polyester B) containing 0.3wt% TiO2 particles were pre-crystallized and dried to below 50ppm, respectively, and placed in spinning silos A and B. The spinning process was carried out using a core-sheath composite. The spinning variety was 100T-36-POY, the assembly cycle was 16 days, and the number of broken yarns was 0.3 times / T. The resulting POY was false-twisted to produce a barrier composite fiber. The resulting fiber had a TiO2 content of 7.0wt%, a sheath thickness of 2.4μm, a fiber strength-elongation product of 17.0, and a boiling water shrinkage of 4.8%. The resulting fiber was made into a fabric with a cover factor of 2000, and the barrier rate of the fabric was measured to be 90%. The hue values ​​of the resulting fabric after dyeing are shown in Table 2.

[0089] Example 14

[0090] 50 parts by weight of a polyethylene terephthalate (PET) copolymer (core component, polyester A) containing 1.5%wt isophthalic acid units and 17.0wt% TiO2 particles, and 50 parts by weight of a semi-dull polyester (sheath component, polyester B) containing 0.3wt% TiO2 particles were pre-crystallized and dried to below 50ppm, respectively, and placed in spinning silos A and B. Spinning was carried out in a core-sheath composite form. The spinning variety was 100T-36-POY, the assembly cycle was 14 days, and the number of broken yarns was 0.3 times / T. The obtained POY was false-twisted to produce a barrier composite fiber. The obtained fiber had a TiO2 content of 8.7wt%, a sheath thickness of 2.0μm, a fiber strength-elongation product of 16.8, and a boiling water shrinkage of 5.1%. The obtained fiber was made into a fabric with a cover factor of 2000, and the barrier rate of the fabric was measured to be 93%. The hue value of the obtained fabric after dyeing is shown in Table 2.

[0091] Example 15

[0092] 90 parts by weight of a polyethylene terephthalate (PET) copolymer (core component, polyester A) containing 1.5%wt isophthalic acid units and 17.0wt% TiO2 particles, and 10 parts by weight of a semi-dull polyester (sheath component, polyester B) containing 0.3wt% TiO2 particles were pre-crystallized and dried to below 50ppm, respectively, and placed in spinning silos A and B. The spinning process was carried out using a core-sheath composite structure. The spinning variety was 100T-36-POY, the assembly cycle was 6 days, and the number of broken yarns was 1.0 times / T. The resulting POY was false-twisted to produce a barrier composite fiber. The resulting fiber had a TiO2 content of 15.3wt%, a sheath thickness of 0.3μm, a fiber strength-elongation product of 12.4, and a boiling water shrinkage of 5.3%. The resulting fiber was made into a fabric with a cover factor of 2000, and the barrier rate of the fabric was measured to be 99%. The hue values ​​of the resulting fabric after dyeing are shown in Table 2.

[0093] Example 16

[0094] 93 parts by weight of a polyethylene terephthalate (PET) copolymer (core component, polyester A) containing 1.5%wt isophthalic acid units and 17.0wt% TiO2 particles, and 7 parts by weight of a semi-dull polyester (sheath component, polyester B) containing 0.3wt% TiO2 particles were pre-crystallized and dried to below 50ppm, respectively, and placed in spinning silos A and B. Spinning was performed using a core-sheath composite form. The spinning variety was 100T-36-POY, the assembly cycle was 6 days, and the number of broken yarns was 1.2 times / T. The resulting POY was false-twisted to produce a barrier composite fiber. The resulting fiber had a TiO2 content of 15.8wt%, a sheath thickness of 0.2μm, a fiber strength-elongation product of 11.9, and a boiling water shrinkage of 5.1%. The resulting fiber was made into a fabric with a cover factor of 2000, and the fabric's barrier efficiency was measured to be 99%. The raw ground and color tone values ​​of the resulting fabric after dyeing are shown in Table 2.

[0095] Example 17

[0096] 95 parts by weight of polyethylene terephthalate (PET) (core component, polyester A) containing 1.5%wt isophthalic acid units and 17.0wt% TiO2 particles, and 5 parts by weight of semi-dull polyester (sheath component, polyester B) containing 1.0wt% TiO2 particles were pre-crystallized and dried to below 50ppm, respectively, and placed in spinning silos A and B. Spinning was carried out in a core-sheath composite form. The spinning variety was 100T-36-POY, the assembly cycle was 6 days, and the number of broken yarns was 1.5 times / T. The obtained POY was false-twisted to produce a barrier composite fiber. The obtained fiber had a TiO2 content of 16.2wt%, a sheath thickness of 0.1μm, a fiber strength-elongation product of 11.4, and a boiling water shrinkage of 5.6%. The obtained fiber was made into a fabric with a cover factor of 2000, and the barrier rate of the fabric was measured to be 99%. The hue value of the obtained fabric after dyeing is shown in Table 2.

[0097] Example 18

[0098] 70 parts by weight of polyethylene terephthalate (PET) (core component, polyester A) containing 1.5%wt isophthalic acid units, 0.33wt% SiO2 particles, and 16.67wt% TiO2 particles, and 30 parts by weight of semi-dull polyester (sheath component, polyester B) containing 0.3wt% TiO2 particles were pre-crystallized and dried to below 50ppm, respectively, and placed in spinning silos A and B. The spinning process was carried out in a core-sheath composite form. The spinning variety was 100T-36-POY, the assembly cycle was 16 days, and the number of broken yarns was 0.4 times / T. The resulting POY was false-twisted to produce a barrier composite fiber. The resulting fiber had a total inorganic particle content of 12.0wt%, a sheath thickness of 1.0μm, a fiber strength-elongation product of 15.7, and a boiling water shrinkage of 5.2%. The resulting fiber was made into a fabric with a cover factor of 2000, and the barrier rate of the fabric was measured to be 94%. The hue values ​​of the resulting fabric after dyeing are shown in Table 2.

[0099] Example 19

[0100] 70 parts by weight of polyethylene terephthalate (PET) (core component, polyester A) containing 1.5%wt isophthalic acid units, 0.06wt% SiO2 particles, and 16.94wt% TiO2 particles, and 30 parts by weight of semi-dull polyester (sheath component, polyester B) containing 0.3wt% TiO2 particles were pre-crystallized and dried to below 50ppm, respectively, and placed in spinning silos A and B. The spinning process was carried out using a core-sheath composite structure. The spinning variety was 100T-36-POY, the assembly cycle was 16 days, and the number of broken yarns was 0.4 times / T. The resulting POY was false-twisted to produce a barrier composite fiber. The resulting fiber had a total inorganic particle content of 12.0wt%, a sheath thickness of 1.0μm, a fiber strength-elongation product of 16.1, and a boiling water shrinkage of 4.9%. The resulting fiber was made into a fabric with a cover factor of 2000, and the barrier efficiency of the fabric was measured to be 96%. The hue values ​​of the resulting fabric after dyeing are shown in Table 2.

[0101] Comparative Example 1

[0102] 70 parts by weight of polyethylene terephthalate (PET) containing no isophthalic acid units and 17% TiO particles (core component, polyester A) and 30 parts by weight of semi-dull polyester containing 0.3% TiO particles (sheath component, polyester B) were pre-crystallized and dried to below 50 ppm. The fibers were then placed in spinning silos A and B, respectively, and spun using a core-sheath composite method. The spinning product was 100T-36-POY, the assembly cycle was 4 days, and the number of broken yarns was 0.4 per ton. The resulting POY was false-twisted to produce a barrier composite fiber. The resulting fiber had a TiO content of 12.0% by weight, a sheath thickness of 1.0 μm, a fiber strength-elongation product of 15.0, and a boiling water shrinkage of 4.5%. The resulting fiber was made into a fabric with a cover factor of 2000, and the barrier performance of the fabric was measured to be 96%. The hue values ​​of the resulting fabric after dyeing are shown in Table 3.

[0103] Because the polyester A component, which contains a large amount of inorganic particles, does not contain isophthalic acid structural units that can reduce crystallinity and expand the gaps between molecular chains, the inorganic particles have difficulty dispersing in the polyester A, resulting in a large amount of agglomeration. This leads to a rapid increase in the filter pressure during spinning, a significant reduction in the assembly cycle, and increased spinning costs. Furthermore, due to the high molecular crystallinity, dye molecules have difficulty entering the molecular chains during dyeing, resulting in poor fiber color development.

[0104] Comparative Example 2

[0105] 70 parts by weight of a polyethylene terephthalate (PET) copolyester (core component, polyester A) containing 3.5%wt isophthalic acid units and 17wt% TiO2 particles, and 30 parts by weight of a semi-dull polyester (sheath component, polyester B) containing 0.3wt% TiO2 particles were pre-crystallized and dried to below 50ppm. The fibers were then placed in spinning silos A and B, respectively, and spun in a core-sheath composite format. The spinning product was 100T-36-POY, with a 17-day assembly cycle and 2 yarn breakages per ton. The resulting POY was false-twisted to produce a barrier composite fiber. The resulting fiber had a TiO2 content of 12.0wt%, a sheath thickness of 1.0μm, a fiber strength-elongation product of 10.2, and a boiling water shrinkage of 13.3%. The resulting fiber was made into a fabric with a cover factor of 2000, and the barrier performance of the fabric was measured to be 96%. The hue values ​​of the resulting fabric after dyeing are shown in Table 3.

[0106] The excessive addition of isophthalic acid copolymers to polyester A significantly reduces molecular chain regularity, impairing the polymer's crystallization and orientation capabilities. This leads to reduced fiber strength and elongation, poorer dimensional stability, and a significant decrease in fiber practical performance. Furthermore, due to the deterioration in fiber properties, the number of broken yarns increases, significantly reducing spinnability and increasing costs.

[0107] Comparative Example 3

[0108] 70 parts by weight of a polyethylene terephthalate (PET) copolyester (core component, polyester A) containing 1.5%wt isophthalic acid units and 5.0wt% TiO2 particles, and 30 parts by weight of a semi-dull polyester (sheath component, polyester B) containing 0.3wt% TiO2 particles were pre-crystallized and dried to below 50ppm, respectively, and placed in spinning silos A and B. The spinning process was carried out using a core-sheath composite structure. The spinning variety was 100T-36-POY, the assembly cycle was 18 days, and the number of broken yarns was 0.2 times / T. The resulting POY was false-twisted to produce a barrier composite fiber. The resulting fiber had a TiO2 content of 3.6wt%, a sheath thickness of 1.0μm, a fiber strength-elongation product of 17.8, and a boiling water shrinkage of 4.3%. The resulting fiber was made into a fabric with a cover factor of 2000, and the barrier rate of the fabric was measured to be 88%. The hue values ​​of the resulting fabric after dyeing are shown in Table 3.

[0109] Due to the low content of inorganic particles in the fiber, the fiber fabric cannot achieve the required anti-permeability effect.

[0110] Comparative Example 4

[0111] 70 parts by weight of a polyethylene terephthalate (PET) copolyester (core component, polyester A) containing 1.5%wt isophthalic acid units and 50.0wt% TiO2 particles, and 30 parts by weight of a semi-dull polyester (sheath component, polyester B) containing 0.3wt% TiO2 particles were pre-crystallized and dried to below 50ppm, respectively, and placed in spinning silos A and B. Spinning was carried out in a core-sheath composite form. The spinning variety was 100T-36-POY, the assembly cycle was 4 days, and the number of broken yarns was 2.0 times / T. The resulting POY was false-twisted to produce a barrier composite fiber. The resulting fiber had a TiO2 content of 35.1wt%, a sheath thickness of 1.0μm, a fiber strength-elongation product of 9.8, and a boiling water shrinkage of 4.7%. The resulting fiber was made into a fabric with a cover factor of 2000, and the barrier rate of the fabric was measured to be 99%. The hue value of the resulting fabric after dyeing is shown in Table 3.

[0112] Because inorganic particles lack ductility, excessive amounts of them in fibers result in low fiber strength, poor usability, and spinnability. Furthermore, a high content of inorganic particles in fibers also increases the flow of inorganic particles through the component filter during spinning, leading to a rapid increase in filtration pressure, a short component cycle, and increased costs.

[0113] Table 3

Claims

1. Anti-permeable polyester composite fiber, mainly composed of a core component of polyester A and a sheath component of polyester B, and the content of inorganic particles in polyester A is greater than that in polyester B, characterized in that: The polyester A is mainly composed of terephthalic acid structural units, aliphatic diol structural units, and isophthalic acid structural units, and the isophthalic acid structural units account for 0.5 - 3.0 wt% of the polyester A; the composite fiber contains inorganic particles accounting for 5 - 20 wt% of the composite fiber.

2. The anti-permeable polyester composite fiber according to claim 1, wherein: The content of inorganic particles in the polyester A is 6.5 - 40.0 wt%.

3. The anti-permeable polyester composite fiber according to claim 1 or 2, characterized in that: The polyester B is one or more of polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, cation-modified polyethylene terephthalate, cation-modified polytrimethylene terephthalate, or cation-modified polybutylene terephthalate.

4. The anti-permeable polyester composite fiber according to claim 1 or 2, characterized in that: The thickness of the sheath component on the composite fiber is 0.2 - 2.0 microns.

5. The anti-permeable polyester composite fiber according to claim 1 or 2, characterized in that: The content of inorganic particles in the polyester B is 0 - 0.5 wt%.

6. The anti-permeable polyester composite fiber according to claim 1 or 2, characterized in that: The inorganic particles are one or more of titanium dioxide, silicon dioxide, barium sulfate, and magnesium oxide.

7. The anti-permeable polyester composite fiber according to claim 1 or 2, characterized in that: The inorganic particles are a mixture of silicon dioxide and titanium dioxide, and the weight ratio of silicon dioxide to titanium dioxide is 1:10 - 500.

8. The anti-permeable polyester composite fiber according to claim 1, characterized in that: The anti-permeability rate of the composite fiber is 93 - 99%.

9. The anti-permeable polyester composite fiber according to claim 1, characterized in that: The L value of the composite fiber is 90 - 97, and the b value is -4 - 6; the L value of the composite fiber after deep black dyeing is 13 - 16.

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