Multi-layer cross-section composite fiber and its textile

Abstract

A multi-layer laminated cross section composite fiber has a multi-layer structure in which at least two or more components are alternately laminated in 3 to 15 layers in the cross section of a single yarn of the fiber, the outermost layer of the multi-layer cross section structure being made of polymer B with an inorganic particle content of 5.0 wt% or less, and at least one layer in the composite fiber being made of polymer A with an inorganic particle content of 10 to 70 wt%. The composite fiber and its textiles have good spinnability and advanced processability, as well as excellent anti-transparency, heat-shielding properties, ultraviolet protection properties, and resistance to discoloration after wetting with water.

Description

Technical Field

[0001] The present invention relates to a multilayer cross-section composite fiber, and specifically to a multilayer cross-section composite fiber in which polymers with different contents of at least two types of inorganic particles are alternately laminated, and a textile obtained from this fiber.

Background Art

[0002] In the field of clothing, visual shielding performance is an important performance of textiles and is related to the most basic body shielding function. In the fields of decoration and military, it is related to special visual requirements such as one-way perspective and camouflage. Also, as the large-scale use of chlorofluorocarbons and environmental pollution are becoming increasingly serious worldwide, the ozone layer in the atmosphere is being severely damaged. Long-term exposure to ultraviolet radiation reduces the lifespan of organic molecules, reduces the body's immune function, damages the skin, causes dermatitis, erythema, freckles, and skin cancer, and also causes eye diseases and cataracts. In addition, especially in summer, the weather is hot, and clothes with a certain degree of heat insulation performance are popular among consumers.

[0003] Also, in the field of clothing, color fading and discoloration of clothing are an important performance of textiles. After a large amount of sweat is discharged from the body or the clothes are wet by rain, the clothes stick to the skin, and the areas wet by sweat or rain become darker than the dry areas, affecting the aesthetics. Also, during the exercise process, competitors judge the fatigue level of the other party based on the amount of sweat the other party has produced, and thereby rationally apply competitive means to win the game. For this reason, those that do not cause color fading and discoloration when the clothes are wet are popular among summer consumers.

[0004] Chinese Patent CN103628180A discloses an ultra-high extinction memory fiber and a manufacturing method. This fiber has a core-sheath composite structure. In order to overcome the problem of thread breakage generated by ordinary full dull fibers in the weaving process, a lower amount than that of titanium oxide in the core is added to the sheath to improve the weaving permeability. Moreover, a large amount of titanium oxide fine particles are added to the core to achieve an anti-transparency effect. However, the amount of titanium oxide added to the core of this composite fiber is 3% or more. If a large amount is added, excellent anti-transparency and ultraviolet protection effects can be obtained, but the spinnability and the strength of the raw yarn are reduced, thread breakage becomes apparent in the weaving process, and the cost also increases. On the contrary, if the amount of titanium oxide added to the core is low, it has the performance of ordinary full dull, but the anti-transparency and ultraviolet protection effects are inferior due to the reduction of the added amount.

[0005] Japanese Patents JP-A-11-269721, JP-A-2008-223171, and JP-A-2013-44055 also disclose core-sheath composite fibers. By adding titanium oxide particles to the core component, anti-transparency and ultraviolet protection effects are obtained. Similarly, if a large amount of titanium oxide is added to the core of the composite fiber, excellent anti-transparency and ultraviolet protection effects can be obtained, but the spinnability and the strength of the raw yarn are reduced, thread breakage becomes apparent in the weaving process, and the cost also increases. On the contrary, if the amount of titanium oxide added is low, it has the performance of ordinary full dull, but the anti-transparency and ultraviolet protection effects are inferior due to the reduction of the added amount.

[0006] Japanese Patent Application Laid-Open No. 11-181627 discloses multilayer laminated fibers. The disclosed polyester composite staple fibers, which are excellent in spinnability, opacity, and heat shielding performance, are composed of two types of polyesters with different white pigment contents. Among them, the white pigment content in the polyester with a large amount of white pigment is 1.5 wt% to 10.0 wt%, and the white pigment content in the polyester with a small amount of white pigment is 0.5 wt% or less. There are multilayer embodiments in the fiber cross-section such as core-sheath or concentric circles disclosed in this patent. By arranging the polyester with a large amount of white pigment as the innermost layer and the polyester with a small amount of white pigment as the outermost layer, the deterioration of spinnability can be avoided. The anti-see-through performance of the fibers obtained by such an implementation method was improved compared to ordinary full-dull polyester, but a higher anti-see-through effect could not be achieved.

Summary of the Invention

Problems to be Solved by the Invention

[0007] An object of the present invention is to provide a multilayer laminated cross-section composite fiber excellent in anti-see-through performance, ultraviolet ray prevention performance, heat shielding performance, and discoloration prevention performance, and a textile formed therefrom.

Means for Solving the Problems

[0008] The technical solution of the present invention is as follows. A multilayer laminated cross-section composite fiber having a multilayer structure in which at least two or more components are alternately laminated in 3 to 15 layers in the cross-section of the single filament. The outermost layer of the multilayer cross-section structure is made of polymer B with an inorganic particle content of 5.0 wt% or less. At least one layer in the composite fiber is made of polymer A with an inorganic particle content of 10.0 to 70.0 wt%, and the polymer A is 10 to 70 wt% of the entire composite fiber.

[0009] In the composite fiber, the content of inorganic particles from polymer A is preferably 7.0 to 30.0 wt%, more preferably 8.0 to 20.0 wt%, and still more preferably 12.0 to 15.0 wt%. In the polymer A, the content of the inorganic particles is preferably 15 to 60 wt%. In the cross-section of the composite fiber single filament, preferably, it has a multilayer structure in which polymer A and polymer B are alternately laminated in 3 to 9 layers, and more preferably, it has a multilayer structure in which polymer A and polymer B are alternately laminated in 3 to 5 layers. Preferably, the outermost layer area of the multilayer structure is 5 to 30% of the total cross-sectional area of the single filament. Preferably, the polymers constituting the composite fiber are polyester, polyamide, polypropylene or polyurethane. The composite fiber has an absolute value of the reflectance difference of visible light of 550 nanometers in the dry and wet states, preferably less than 5.0%, and more preferably less than 3.0%. The toughness of the composite fiber is preferably 15.0 or more, and more preferably 19.0 or more. The present invention provides a textile made of the multilayer laminated cross-section composite fiber. The fabric has an absolute value of the reflectance difference of visible light of 550 nanometers in the dry and wet states, preferably less than 5.0%, and more preferably less than 3.0%.

[0010] Through the structure of the multilayer laminated cross-section, the polymer A with a high inorganic particle content and the polymer B with a low inorganic particle content are alternately arranged in the fiber. The obtained composite fiber has good anti-see-through performance, ultraviolet ray prevention performance, heat insulation performance, and can maintain good strength and elongation characteristics. Moreover, the obtained composite fiber and the textile formed therefrom are excellent in anti-fading and discoloration prevention performance.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0012] In the cross-section of a single filament of the multilayer cross-section composite fiber of the present invention, it has a multilayer structure in which at least two types of components are alternately laminated in 3 to 15 layers. The outermost layer of the multilayer cross-section structure is made of polymer B with an inorganic particle content of 5.0 wt% or less, and at least one layer in the composite fiber is made of polymer A with an inorganic particle content of 10.0 to 70.0 wt%.

[0013] In the present invention, by arranging polymer A with a high inorganic particle content in the inner layer of the multilayer cross-section composite fiber, in the fiber processing process, the fiber has good passing properties, and in the subsequent weaving process, problems such as yarn breakage do not occur.

[0014] The higher the content of inorganic particles, the better the anti-seepage performance of the fiber. However, when a large amount of inorganic particles is added, the strength and elongation of the fiber are significantly reduced. In order to maintain the properties such as the strength and elongation of the fiber, it is necessary to reduce the addition amount of polymer A with a high inorganic particle content. In this case, polymer A is placed as close as possible to the outer layer in the fiber cross-section, whereby a better anti-seepage effect can be obtained than that of a core-sheath fiber with the same inorganic particle content.

[0015] On the other hand, in order to meet specific strength and elongation, the fiber distributes polymer A in the form of multiple layers in the fiber and reduces the component of polymer A close to the outer layer in the fiber cross-section. The anti-seepage performance is slightly reduced, but the multilayer structure can disperse polymer A more uniformly in the fiber, improve the strength and elongation of the raw yarn, and meet specific application conditions.

[0016] In the case of the polymer A, when the inorganic particle content is less than 10.0 wt%, there are no problems with the spinnability of the polymer A and the physical properties of the composite fiber. However, a small amount of inorganic particles is disadvantageous for the reflection and absorption of light, and the anti-sheer performance, ultraviolet protection performance, and heat insulation performance of the composite fiber are significantly reduced and cannot reach the required level. In the polymer A, the higher the content of inorganic particles, the better the anti-sheer performance, ultraviolet protection ability, heat insulation performance, and prevention of discoloration after water immersion of the composite fiber. However, in the polymer A, when the inorganic particle content is higher than 70.0 wt%, it affects the spinnability of the polymer A. In the spinning process, yarn breakage and single-filament flow phenomena are likely to occur, and the strength and elongation of the obtained composite fiber are inferior, which affects its subsequent use. Therefore, considering the anti-sheer performance, ultraviolet protection ability, heat insulation performance, and productivity of the composite fiber comprehensively, it is preferable that the content of inorganic particles in the polymer A is 15.0 - 50.0 wt%.

[0017] The polymer A accounts for 10 - 70 wt% of the entire composite fiber. When the content of the polymer A in the composite fiber is less than 10 wt%, a normal composite multi-layer cross-sectional structure cannot be guaranteed, and the content of inorganic particles in the composite fiber also decreases, resulting in a decline in the anti-sheer performance, ultraviolet protection performance, heat insulation performance, and prevention of discoloration after water immersion of the fiber. The higher the content of the polymer A, the better the anti-sheer performance of the composite fiber. However, since the cost of the polymer component with a high inorganic particle content is high, the cost of the entire fiber increases, and after the inorganic particle content increases, the basic physical properties of the fiber decrease. In the present invention, it is preferable that the content of the polymer A in the composite fiber is 15 - 60 wt%.

[0018] The present invention does not limit the form of the multi-layer cross-sectional structure, and it may be concentric arrangement, parallel arrangement, perpendicular cross arrangement between layers, etc. When the multi-layer cross-sectional structure is in concentric arrangement, the innermost central layer may be a polymer layer or a hollow layer.

[0019] If the layers formed of polymer A and the layers formed of polymer B alternate and are arranged at intervals, even when the content of polymer A in the fiber is low and the cross-section of the composite fiber has any kind of multilayer cross-sectional structure, the composite fiber can achieve excellent anti-see-through performance, UV protection performance, heat insulation performance, and color fading resistance performance after water immersion. At the same time, the thickness of the outermost layer can be controlled in the alternating arrangement structure.

[0020] In the multilayer cross-section composite fiber described in the present invention, the inorganic particle content from polymer A is 7.0 to 30.0 wt%. In the composite fiber, when the content of inorganic particles from polymer A is low, none of the anti-see-through performance, UV protection performance, heat insulation performance, and color fading resistance performance after water immersion of the fiber is ideal. In the composite fiber, the higher the content of inorganic particles from polymer A, the better the performance of the composite fiber. However, when the content of inorganic particles from polymer A reaches a specific value, the improvement of the overall performance of the fiber gradually decreases. Moreover, since the cost of the polymer component with a high inorganic particle content is high, the cost of the entire fiber increases, and after the inorganic particle content increases, the basic physical properties of the fiber decrease. Therefore, in the fiber described in the present invention, the inorganic particle content from polymer A is preferably 8.0 to 20.0%, and more preferably 12.0 to 15.0%.

[0021] The single filament of the composite fiber described in the present invention has a cross-sectional structure of 3 to 15 layers. If the number of layers of the multilayer cross-sectional structure is too many, more than 15 layers, abnormalities often occur in the formation of the cross-sectional structure, and at the same time, the basic physical properties of the fiber are inferior. In order to balance the basic physical properties of the fiber with the anti-see-through performance and heat insulation performance, in the present invention, the number of layers of the multilayer cross-sectional structure is preferably 3 to 9 layers, and more preferably 3 to 5 layers.

[0022] When the inorganic particle content in the polymer that comes into contact with the spinning equipment is high, the inorganic particles and components such as the guide block will rub against each other, affecting the lifespan of the equipment and the spinnability of the polymer. In order to ensure the spinnability of the polymer and avoid the influence of inorganic particles on the spinning equipment, the present invention preferably uses polymer B with a low inorganic particle content exposed on the fiber surface, that is, the outermost layer of the multi-layer cross-sectional structure is formed by the polymer B. The polymer B with a low inorganic particle content covers the polymer A with a high inorganic particle content, avoiding a large amount of inorganic particles directly contacting the oil supply nozzle, each guide block of the spinning machine, rollers, etc. during spinning, reducing the frictional resistance, and ensuring good process passing performance of the yarn. Moreover, it can avoid the contamination of the oil supply nozzle, guide block, and rollers caused by the shedding of high-content inorganic particles directly contacting the various parts of the spinning machine. Additionally, it can prevent the influence of inorganic particle shedding on the anti-seepage performance, UV protection performance, and heat insulation performance of the multi-layer cross-sectional composite fiber, and also reduce the yarn breakage rate in the post-processing process.

[0023] Furthermore, in order not to significantly affect the anti-seepage performance, UV protection performance, and heat insulation performance of the composite fiber, the area of the outermost layer formed by polymer B is preferably 5 - 30% of the total cross-sectional area of the single filament. If the area ratio of the outermost layer formed by polymer B is too large, the impact on the anti-seepage performance of the entire composite fiber will be significant, and the anti-seepage performance of the composite fiber will be poor. The smaller the area of the outermost layer formed by polymer B, the better the anti-seepage performance of the composite fiber. However, after the area ratio is reduced below a certain ratio, the improvement range of the anti-seepage performance of the composite fiber becomes small. Moreover, during yarn processing and use, surface wear due to friction is likely to occur. Therefore, in the present invention, it is more preferable that the area of the outermost layer formed by polymer B is 10 - 20% of the total cross-sectional area.

[0024] The inorganic particles described in the present invention may be titanium oxide, calcium carbonate, barium sulfate, zinc oxide, silicon dioxide, boron nitride, etc. Among them, titanium oxide, calcium carbonate, barium sulfate or zinc oxide is preferable. The inorganic particles contained in the polymer A and the polymer B may be the same or different. In order to obtain a composite fiber with higher anti-permeation performance and ultraviolet ray prevention performance, the inorganic particles described in the present invention are preferably titanium oxide.

[0025] The refractive index of the inorganic particles is preferably 1.6 to 3.0, and more preferably 2.0 to 3.0.

[0026] Depending on the crystal form, the titanium oxide is divided into anatase-type titanium oxide and rutile-type titanium oxide. Usually, the crystals of anatase-type titanium oxide that are often used have an unstable structure and are prone to generating radicals. When radicals accumulate to a certain amount, they will affect the light fastness of the polymer. Therefore, when a large amount of anatase-type titanium oxide is contained in the fiber, the light resistance of the fiber is inferior. In order for the fiber to have better light fastness, the inorganic particles contained in the polymer A described in the present invention are preferably rutile-type titanium oxide.

[0027] The present invention includes various thermoplastic polymers without particularly limiting the polymer components constituting the polymer A. It may be a polyester polymer or a polyamide polymer, and may also be a polyolefin polymer or polyurethane. Specifically, the polyester polymer may be a homopolymer such as polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, etc., or a copolymer thereof. The polyamide polymer may be polyamide 6, cationic dye-dyeable polyamide 6, polyamide 66, etc., and the polyolefin polymer may also be polyethylene, polypropylene, polybutadiene, etc.

[0028] The present invention is not particularly limited with respect to the polymer components constituting polymer B, and includes various thermoplastic polymers. Depending on the polymer raw material, it may be a polyester polymer, a polyamide polymer, a polyolefin polymer, or a polyurethane. Specifically, the polyester polymer may be a homopolymer such as polyethylene terephthalate, polytrimethylene terephthalate, or polybutylene terephthalate, or a copolymer thereof. Depending on the function, the polyester polymer may be a disperse dye-dyeable polyester, a cationic dye-dyeable polyester, an easily soluble polyester, a conductive polyester, an antistatic polyester, a hygroscopic polyester, a low-friction polyester, etc. The polyamide polymers may be polyamide 6, cationic dye-dyeable polyamide 6, polyamide 66, etc. The polyolefin polymers may be polyethylene, polypropylene, polybutadiene, etc. Depending on the inorganic particle content in polymer B, the sheath component may be a bright polymer, a semi-dull polymer, a full-dull polymer, such as bright polyester, semi-dull polyester, full-dull polyester, etc.

[0029] When polymer B, which forms the outermost layer of the fiber, has poor spinnability after being given various functions and poor long-term stability of the corresponding functions during subsequent use, a functional polymer component may be added inside the outermost layer and alternately arranged with polymer A or polymer B as a single layer. In this case, polymer B may be selected from polymers containing only 5.0 wt% or less of inorganic particles. The functional polymer may be a hygroscopic polymer that improves the hygroscopicity rate of the entire fiber, an antibacterial polymer that improves the antibacterial property of the entire fiber, a flame-retardant polymer, etc.

[0030] The present invention is not particularly limited with respect to the form of the fiber, and it may be a long fiber or a short fiber. When the fiber is infiltrated by a liquid (in a wet state), a liquid layer exists, so the refraction and reflection effects of light change compared to the fiber in the normal dry state. If the refraction and reflection effects of light change too much, the color tone difference between the wet and dry state fibers will be too large. In particular, when used for summer clothing, the color tone difference between the areas soaked by sweat and the non-soaked areas is large, which affects the aesthetics. In the present invention, the number of fiber cross-sectional layers, the inorganic particle content in polymer A and polymer B, and the content in the composite fiber of polymer A and polymer B are related to the degree of change in the refraction and reflection effects of light when the fiber is in a wet and dry state. The degree of change is represented by the absolute value of the difference in the reflectance of visible light with a wavelength of 550 nanometers when the composite fiber is in a dry and wet state. The smaller the absolute value, the closer the color of the composite fiber in the dry and wet states, and the better the aesthetics of summer clothing. The composite fiber described in the present invention preferably has an absolute value of the difference in the reflectance of visible light with a wavelength of 550 nanometers lower than 5.0% in the dry and wet states.

[0031] The tenacity of the raw yarn of the multi-layer cross-sectional composite fiber described in the present invention is 15.0 or more. In fiber use, in order to ensure good spinning, weaving, and product use process passability and tear resistance, the tenacity of the raw yarn needs to meet a specific level. When the tenacity of the raw yarn is 15.0 or less, yarn breakage may occur in the weaving process, and there is a high possibility of poor passability. Moreover, the manufactured product does not have good burst strength, which affects the service life.

[0032] The composite fiber of the present invention is used to manufacture textiles, and the multi-layer cross-sectional composite fiber of the present invention can be used partially or entirely in the textiles. The textiles include woven fabrics, knitted fabrics, third textiles, non-woven products, multi-directional textiles, three-dimensional textiles, composite textiles, etc. When manufacturing textiles using the composite fiber of the present invention as a part, the other fibers can be ordinary polyester fibers, polyamide fibers, polyolefin fibers, polyurethane fibers, etc. On the premise of ensuring that the difference in the reflectance of visible light with a wavelength of 550 nanometers under the dry and wet states of the textile is 5.0% or less, it can be widely used as the fabric for summer clothes.

[0033] The measurement method for each parameter according to the present invention is as follows. (1) Light-proof performance Using a D65 light source, irradiate a white board and a black board of the reference color respectively, measure their L* values, and let the L* values be L(white) and L(black) respectively. Then, prepare textile fabric samples (10×10 cm), place each on the white board and black board of the reference color, irradiate the samples with a D65 light source, measure their L* values, and let the L* values be L(white + cloth) and L(black + cloth) respectively. Then, calculate the data of the light-proof performance with the following formula. It can be seen that the greater the obtained data of the light-proof performance, the better the light-proof performance of the sample. Repeat the measurement for 10 samples each and take the average value. Light-proof property: (1 - (L(white + cloth) - L(black + cloth)) / (L(white) - L(black)) × 100%.

[0034] (2) UPF (ultraviolet protection performance) UPF, which is an ultraviolet protection parameter, is evaluated according to the standard GB / T 6529. Repeat the measurement for 10 samples each and take the average value. If the UPF value is 50 or more, it is judged as "〇"; if the UPF value is 40 or more and less than 50, it is judged as "△"; if the UPF value is less than 40, it is judged as "×".

[0035] (3) Types and contents of inorganic particles in textiles Take about 4 g of the textile, melt it to prepare a sample, and measure the content of metal elements with an X-ray fluorescence analyzer (manufacturer: Rigaku, model number: ZSX PrimusIII+). Then, measure the weight of inorganic particles in the fiber by the combustion ash method, and estimate the types and contents of inorganic particles in the textile based on the metal element content and the weight of inorganic particles. Repeat the measurement for 10 samples each and take the average value.

[0036] (4) Cross-sectional ratio and outermost layer area ratio of each component in the fiber Take a cross-sectional photo of this composite fiber by SEM, print the cross-sectional photo on paper, and measure the cross-sectional area S1 of the polymer B component with a low inorganic particle content and the cross-sectional area S2 of the polymer A component with a high inorganic particle content using a planimeter. The polymer B component ratio = S1 / (S1 + S2), and the polymer A component ratio = S2 / (S1 + S2). For the cross-section of this composite fiber taken by SEM, measure the outermost layer area and the total cross-sectional area, and the outermost layer cross-sectional area ratio = outermost layer area / total fiber area. Repeat the measurement for 10 samples each and take the average value.

[0037] (5) Inorganic particle content in each component Take a fiber sample of a specific weight (N1), and measure the weight of the metal element (estimating the weight of inorganic particles M1) using an X-ray fluorescence analyzer (manufacturer: Rigaku, model number: ZSX PrimusIII+). Determine the composite ratio of polymer A and polymer B in the fiber and the outermost layer cross-sectional area ratio (refer to measurement method 4) based on the cross-sectional photo, and calculate the ratio of the outermost layer to the total fiber. Then, perform an elution treatment using an alkaline solution, control the depletion rate, and remove the outermost layer polymer B. For the fiber remaining after the elution treatment (weight N2), measure the weight of the metal element in the remaining part (estimating the weight of inorganic particles M2) using an X-ray fluorescence analyzer (manufacturer: Rigaku, model number: ZSX PrimusIII+). Repeat the measurement for 10 samples each and take the average value.

[0038]

Number

[0039] (6) Reflectance of visible light According to the standards and terminology in GB / T3291.2 and GB / T3291.3, convert the fiber into the form of undyed textiles. Ensure no wrinkles and no damages, cut the textiles into a size of 5 cm * 5 cm to prepare samples. Use an integrating sphere photometer, with the surface of the textile away from the skin when worn facing the light source, measure its reflectance, and record the reflectance R1 at a wavelength of 550 nanometers. When measuring the reflectance in the liquid infiltration state, first, immerse the sample in tertiary water and adjust the moisture content of the sample to 100% (the weight after water infiltration is twice the weight before infiltration). Ensure that there are no wrinkles and no scratches. When wearing, face the surface of the textile away from the skin towards the light source, measure its reflectance, and record the reflectance R2 at a wavelength of 550 nanometers; Dry-wet state reflectance difference = |R1 - R2|. Perform repeated measurements on 10 samples each and take the average value.

[0040] (7) Dry-wet state color change and fading determination In accordance with the JIS L 0804:2005 color change and gray scale card judgment criteria, determine and evaluate the color change and fading of textiles in the dry-wet state (the liquid is not limited to water). Perform repeated measurements on 10 samples each and take the average value. Grade 4: Almost no color change and fading, denoted as "〇"; Grade 3 - 4: Slight color change and fading, denoted as "△"; Grade 3 and below: Obvious color change and fading, denoted as "×".

[0041] (8) Fiber toughness In accordance with the standard GB / T14344-2008, measure the strength and elongation of the fiber respectively, and calculate the fiber toughness using the following formula. Toughness = Strength × (Elongation) 1 / 2 。 Perform repeated measurements on 10 samples each and take the average value.

[0042] (9) Light fastness In accordance with the standard JIS L0842, perform 20-hour light irradiation, compare the irradiated sample with the unirradiated control sample, and make a judgment using the standard comparison gray scale card to measure the level of light fastness. Perform repeated measurements on 10 samples each and take the average value. If the light fastness is 4 grades or above, it is judged as "○", and if the light fastness is 3 grades or below, it is judged as "△".

[0043] (10) Rutile-type titanium oxide The obtained fibers are made into a film by melting, and the crystal peak position is measured by an X-ray diffractometer. At the same time, the crystal peak position of normal rutile-type titanium dioxide is measured, and the crystal form of titanium dioxide is determined by comparing the crystal peak positions of both.

[0044] (11) Spinnability During the spinning process, the single-filament flow and yarn breakage are counted. When the single-filament flow and the number of yarn breakages are 1 time / t or less, the spinnability is determined as "〇", and when the single-filament flow and the number of yarn breakages are greater than 1 time / t, the spinnability is determined as "×". Hereinafter, the present invention will be described in detail with reference to examples.

[0045] Example 1 50 parts by weight of polyethylene terephthalate (PET) (polymer A) containing 15.0 wt% of rutile-type TiO2 particles and 50 parts by weight of semi-dull polyester (polymer B) containing 0.3 wt% of TiO2 particles are each pre-crystallized and dried to 50 ppm or less. Each is put into the A and B chip supply hoppers of a spinning machine for spinning, and false-twist processing is carried out to produce long fibers with high anti-transparency performance. The fiber cross-section has a multi-layer concentric structure with 3 layers. Among them, polymer B is in the outermost layer, and the outermost layer area is 20% of the total cross-sectional area. The raw yarn toughness is 17.3. A tubular knitted fabric is made from the obtained fibers, and the anti-transparency performance of the obtained tubular knitted fabric is 94.8%, the dry-wet reflectance difference at a wavelength of 550 nanometers is 1.2%, it has ultraviolet resistance performance, and the light fastness passes.

[0046] Example 2 50 parts by weight of polyethylene terephthalate (PET) (Polymer A) containing 15.0 wt% of rutile-type TiO₂ particles and 50 parts by weight of semi-dull polyester (Polymer B) containing 0.3 wt% of TiO₂ particles are each pre-crystallized and dried to 50 ppm or less. Each is put into the A and B chip supply hoppers of a spinning machine for spinning, and false-twisting processing is carried out to produce long fibers with high anti-transparency performance. The fiber cross-section has a multi-layer concentric structure with 3 layers. Among them, Polymer B is on the outermost layer, and the outermost layer area is 30% of the total cross-sectional area. The raw yarn tenacity is 17.5. A tubular knitted fabric is made from the obtained fibers, and the anti-transparency performance of the obtained tubular knitted fabric is 94.1%, the dry-wet reflectance difference at a wavelength of 550 nanometers is 2.3%, it has ultraviolet resistance performance, and the light fastness passes the test.

[0047] Example 3 50 parts by weight of polyethylene terephthalate (PET) (Polymer A) containing 15.0 wt% of rutile-type TiO₂ particles and 50 parts by weight of semi-dull polyester (Polymer B) containing 0.3 wt% of TiO₂ particles are each pre-crystallized and dried to 50 ppm or less. Each is put into the A and B chip supply hoppers of a spinning machine for spinning, and false-twisting processing is carried out to produce long fibers with high anti-transparency performance. The fiber cross-section has a multi-layer concentric structure with 3 layers. Among them, Polymer B is on the outermost layer, and the outermost layer area is 10% of the total cross-sectional area. The raw yarn tenacity is 17.7. A tubular knitted fabric is made from the obtained fibers, and the anti-transparency performance of the obtained tubular knitted fabric is 94.9%, the dry-wet reflectance difference at a wavelength of 550 nanometers is 1.1%, it has ultraviolet resistance performance, and the light fastness passes the test.

[0048] Example 4 60 parts by weight of polyethylene terephthalate (PET) (Polymer A) containing 15.0 wt% of rutile-type TiO₂ particles and 40 parts by weight of semi-dull polyester (Polymer B) containing 0.3 wt% of TiO₂ particles were each pre-crystallized and dried to 50 ppm or less. Each was put into the A and B chip supply hoppers of a spinning machine for spinning, and false twisting was carried out to produce long fibers with high anti-see-through performance. The fiber cross-section has a multi-layer concentric structure with 3 layers. Among them, Polymer B is on the outermost layer, and the outermost layer area is 20% of the total cross-sectional area. The raw yarn tenacity is 16.3. A tubular knitted fabric was made from the obtained fibers, and the anti-see-through performance of the obtained tubular knitted fabric is 95.1%, the dry-wet reflectance difference at a wavelength of 550 nanometers is 0.9%, it has ultraviolet resistance performance, and the light fastness passed the test.

[0049] Example 5 70 parts by weight of polyethylene terephthalate (PET) (Polymer A) containing 15.0 wt% of rutile-type TiO₂ particles and 30 parts by weight of semi-dull polyester (Polymer B) containing 0.3 wt% of TiO₂ particles were each pre-crystallized and dried to 50 ppm or less. Each was put into the A and B chip supply hoppers of a spinning machine for spinning, and false twisting was carried out to produce long fibers with high anti-see-through performance. The fiber cross-section has a multi-layer concentric structure with 3 layers. Among them, Polymer B is on the outermost layer, and the outermost layer area is 20% of the total cross-sectional area. The raw yarn tenacity is 15.5. A tubular knitted fabric was made from the obtained fibers, and the anti-see-through performance of the obtained tubular knitted fabric is 95.3%, the dry-wet reflectance difference at a wavelength of 550 nanometers is 0.8%, it has ultraviolet resistance performance, and the light fastness passed the test.

[0050] Example 6 30 parts by weight of polyethylene terephthalate (PET) (Polymer A) containing 15.0 wt% of rutile-type TiO₂ particles and 70 parts by weight of semi-dull polyester (Polymer B) containing 0.3 wt% of TiO₂ particles are each pre-crystallized and dried to 50 ppm or less. Each is put into the A and B chip supply hoppers of a spinning machine for spinning, and false-twisting processing is carried out to produce long fibers with high anti-see-through performance. The fiber cross-section has a multi-layer concentric structure with 3 layers. Among them, Polymer B is on the outermost layer, and the outermost layer area is 20% of the total cross-sectional area. The raw yarn tenacity is 17.5. A tubular knitted fabric is made from the obtained fibers, and the anti-see-through performance of the obtained tubular knitted fabric is 95.4%, the dry-wet reflectance difference at a wavelength of 550 nanometers is 0.7%, it has ultraviolet resistance performance, and the light fastness passes.

[0051] Example 7 20 parts by weight of polyethylene terephthalate (PET) (Polymer A) containing 60.0 wt% of rutile-type TiO₂ particles and 80 parts by weight of semi-dull polyester (Polymer B) containing 0.3 wt% of TiO₂ particles are each pre-crystallized and dried to 50 ppm or less. Each is put into the A and B chip supply hoppers of a spinning machine for spinning, and false-twisting processing is carried out to produce long fibers with high anti-see-through performance. The fiber cross-section has a multi-layer concentric structure with 3 layers. Among them, Polymer B is on the outermost layer, and the outermost layer area is 20% of the total cross-sectional area. The raw yarn tenacity is 19.1. A tubular knitted fabric is made from the obtained fibers, and the anti-see-through performance of the obtained tubular knitted fabric is 96.3%, the dry-wet reflectance difference at a wavelength of 550 nanometers is 0.4%, it has ultraviolet resistance performance, and the light fastness passes.

[0052] Example 8 50 parts by weight of nylon 6 (N6) (Polymer A) containing 15.0 wt% of rutile-type TiO₂ particles and 50 parts by weight of semi-dull nylon 6 (Polymer B) containing 0.3 wt% of TiO₂ particles are each pre-crystallized and dried to 50 ppm or less. Each is put into the A and B chip supply hoppers of a spinning machine for spinning, and false twisting is carried out to produce long fibers with high anti-see-through performance. The fiber cross-section has a multi-layer concentric structure with 3 layers. Among them, Polymer B is on the outermost layer, and the outermost layer area is 20% of the total cross-sectional area. The tenacity of the raw yarn is 21.5. A tubular knitted fabric is made from the obtained fibers, and the anti-see-through performance of the obtained tubular knitted fabric is 94.3%, the difference in dry and wet reflectance at a wavelength of 550 nanometers is 1.4%, it has ultraviolet resistance performance, and the light fastness passes the standard.

[0053] Example 9 50 parts by weight of polypropylene (PP) (Polymer A) containing 15.0 wt% of rutile-type TiO₂ particles and 50 parts by weight of semi-dull polypropylene (PP) (Polymer B) containing 0.3 wt% of TiO₂ particles are each pre-crystallized and dried to 50 ppm or less. Each is put into the A and B chip supply hoppers of a spinning machine for spinning, and false twisting is carried out to produce long fibers with high anti-see-through performance. The fiber cross-section has a multi-layer concentric structure with 3 layers. Among them, Polymer B is on the outermost layer, and the outermost layer area is 20% of the total cross-sectional area. The tenacity of the raw yarn is 21.6. A tubular knitted fabric is made from the obtained fibers, and the anti-see-through performance of the obtained tubular knitted fabric is 94.3%, the difference in dry and wet reflectance at a wavelength of 550 nanometers is 1.5%, it has ultraviolet resistance performance, and the light fastness passes the standard.

[0054] Example 10 50 parts by weight of polyethylene terephthalate (PET) (Polymer A) containing 15.0 wt% of rutile-type TiO₂ particles and 50 parts by weight of semi-dull polyester (Polymer B) containing 2.7 wt% of TiO₂ particles are each pre-crystallized and dried to 50 ppm or less. Each is put into the A and B chip supply hoppers of a spinning machine for spinning, and false twisting is carried out to produce long fibers with high anti-transparency performance. The fiber cross-section has a multi-layer concentric structure with 3 layers. Among them, Polymer B is on the outermost layer, and the outermost layer area is 20% of the total cross-sectional area. The raw yarn tenacity is 15.2. A tubular knitted fabric is made from the obtained fibers, and the anti-transparency performance of the obtained tubular knitted fabric is 94.6%, the dry-wet reflectance difference at a wavelength of 550 nanometers is 1.1%, it has ultraviolet resistance performance, and the light fastness passes the test.

[0055] Example 11 50 parts by weight of polyethylene terephthalate (PET) (Polymer A) containing 15.0 wt% of rutile-type TiO₂ particles and 50 parts by weight of semi-dull polyester (Polymer B) containing 5.0 wt% of TiO₂ particles are each pre-crystallized and dried to 50 ppm or less. Each is put into the A and B chip supply hoppers of a spinning machine for spinning, and false twisting is carried out to produce long fibers with high anti-transparency performance. The fiber cross-section has a multi-layer concentric structure with 3 layers. Among them, Polymer B is on the outermost layer, and the outermost layer area is 20% of the total cross-sectional area. The raw yarn tenacity is 15.0. A tubular knitted fabric is made from the obtained fibers, and the anti-transparency performance of the obtained tubular knitted fabric is 94.9%, the dry-wet reflectance difference at a wavelength of 550 nanometers is 1.0%, it has ultraviolet resistance performance, and the light fastness passes the test.

[0056] Example 12 50 parts by weight of polyethylene terephthalate (PET) (Polymer A) containing 15.0 wt% zinc oxide particles and 50 parts by weight of semi-dull polyester (Polymer B) containing 0.3 wt% TiO₂ particles are each pre-crystallized and dried to 50 ppm or less. Each is put into the A and B chip supply hoppers of a spinning machine for spinning, and false-twisting processing is carried out to produce long fibers with high anti-transparency performance. The fiber cross-section has a multi-layer concentric structure with 3 layers. Among them, Polymer B is on the outermost layer, and the outermost layer area is 20% of the total cross-sectional area. The raw yarn tenacity is 15.6. A tubular knitted fabric is made from the obtained fibers, and the anti-transparency performance of the obtained tubular knitted fabric is 94.2%, the dry-wet reflectance difference at a wavelength of 550 nanometers is 3.2%, it has ultraviolet resistance performance, and the light fastness passes the test.

[0057] Example 13 50 parts by weight of polyethylene terephthalate (PET) (Polymer A) containing 15.0 wt% rutile-type TiO₂ particles and 50 parts by weight of semi-dull polyester (Polymer B) containing 0.3 wt% TiO₂ particles are each pre-crystallized and dried to 50 ppm or less. Each is put into the A and B chip supply hoppers of a spinning machine for spinning, and false-twisting processing is carried out to produce long fibers with high anti-transparency performance. The fiber cross-section has a multi-layer concentric structure with 5 layers. Among them, Polymer B is on the outermost layer, and the outermost layer area is 20% of the total cross-sectional area. The raw yarn tenacity is 18.5. A tubular knitted fabric is made from the obtained fibers, and the anti-transparency performance of the obtained tubular knitted fabric is 94.4%, the dry-wet reflectance difference at a wavelength of 550 nanometers is 1.4%, it has ultraviolet resistance performance, and the light fastness passes the test.

[0058] Example 14 50 parts by weight of polyethylene terephthalate (PET) (Polymer A) containing 15.0 wt% of rutile-type TiO₂ particles and 50 parts by weight of semi-dull polyester (Polymer B) containing 0.3 wt% of TiO₂ particles were each pre-crystallized and dried to 50 ppm or less. Each was put into the A and B chip supply hoppers of a spinning machine for spinning, and false-twist processing was carried out to produce long fibers with high anti-see-through performance. The fiber cross-section has a multi-layer concentric structure with 9 layers. Among them, Polymer B is on the outermost layer, and the outermost layer area is 20% of the total cross-sectional area. The raw yarn tenacity is 19.2. A tubular knitted fabric was made from the obtained fibers, and the anti-see-through performance of the obtained tubular knitted fabric is 94.2%, the dry-wet reflectance difference at a wavelength of 550 nanometers is 1.8%, it has ultraviolet resistance performance, and the light fastness passed.

[0059] Example 15 45 parts by weight of polyethylene terephthalate (PET) (Polymer A) containing 30.0 wt% of rutile-type TiO₂ particles, 45 parts by weight of semi-dull polyester (Polymer B) containing 0.3 wt% of TiO₂ particles, and 10 parts by weight of Polymer C containing 0.1 wt% of antibacterial particles were each pre-crystallized and dried to 50 ppm or less. Each was put into the chip supply hopper of a spinning machine for spinning, and false-twist processing was carried out to produce long fibers with high anti-see-through performance. The fiber cross-section has a multi-layer structure with 3 layers. Among them, Polymer C is on the innermost layer, Polymer A is on the middle layer, Polymer B is on the outermost layer, and the outermost layer area is 20% of the total cross-sectional area. The raw yarn tenacity is 15.1. A tubular knitted fabric was made from the obtained fibers, and the anti-see-through performance of the obtained tubular knitted fabric is 95.8%, the dry-wet reflectance difference at a wavelength of 550 nanometers is 0.7%, it has ultraviolet resistance performance, and the light fastness passed.

[0060] Example 16 50 parts by weight of polyethylene terephthalate (PET) (Polymer A) containing 15.0 wt% of anatase-type TiO₂ particles and 50 parts by weight of semi-dull polyester (Polymer B) containing 0.3 wt% of TiO₂ particles are each pre-crystallized and dried to 50 ppm or less. Each is put into the A and B chip supply hoppers of a spinning machine for spinning, and false-twisting processing is carried out to produce long fibers with high anti-see-through performance. The fiber cross-section has a multi-layer concentric structure with 3 layers. Among them, Polymer B is on the outermost layer, and the outermost layer area is 20% of the total cross-sectional area. The raw yarn tenacity is 17.5. A tubular knitted fabric is made from the obtained fibers, and the anti-see-through performance of the obtained tubular knitted fabric is 94.4%, the dry-wet reflectance difference at a wavelength of 550 nanometers is 1.4%, it has ultraviolet resistance performance, and the light fastness passes the test.

[0061] Example 17 50 parts by weight of polyethylene terephthalate (PET) (Polymer A) containing 15.0 wt% of rutile-type TiO₂ particles and 50 parts by weight of semi-dull polyester (Polymer B) containing 0.3 wt% of TiO₂ particles are each pre-crystallized and dried to 50 ppm or less. Each is put into the A and B chip supply hoppers of a spinning machine for spinning, and false-twisting processing is carried out to produce long fibers with high anti-see-through performance. The fiber cross-section has a multi-layer hollow concentric structure with 3 layers. Among them, Polymer B is on the outermost layer, and the outermost layer area is 20% of the total cross-sectional area. The raw yarn tenacity is 16.2. A tubular knitted fabric is made from the obtained fibers, and the anti-see-through performance of the obtained tubular knitted fabric is 94.4%, the dry-wet reflectance difference at a wavelength of 550 nanometers is 1.8%, it has ultraviolet resistance performance, and the light fastness passes the test.

[0062] Example 18 70 parts by weight of polyethylene terephthalate (PET) (Polymer A) containing 10.0 wt% of rutile-type TiO₂ particles and 30 parts by weight of semi-dull polyester (Polymer B) containing 0.3 wt% of TiO₂ particles were each pre-crystallized and dried to 50 ppm or less. Each was put into the A and B chip supply hoppers of a spinning machine for spinning, and false twisting was carried out to produce long fibers with high anti-transparency performance. The fiber cross-section has a multi-layer concentric structure with 3 layers. Among them, Polymer B is in the outermost layer, and the outermost layer area is 20% of the total cross-sectional area. The raw yarn tenacity is 15.1. A tubular knitted fabric was made from the obtained fibers, and the anti-transparency performance of the obtained tubular knitted fabric is 94.1%, the dry-wet reflectance difference at a wavelength of 550 nanometers is 2.7%, it has ultraviolet resistance performance, and the light fastness passed the test.

[0063] Example 19 10 parts by weight of polyethylene terephthalate (PET) (Polymer A) containing 70.0 wt% of rutile-type TiO₂ particles and 90 parts by weight of semi-dull polyester (Polymer B) containing 0.3 wt% of TiO₂ particles were each pre-crystallized and dried to 50 ppm or less. Each was put into the A and B chip supply hoppers of a spinning machine for spinning, and false twisting was carried out to produce long fibers with high anti-transparency performance. The fiber cross-section has a multi-layer concentric structure with 3 layers. Among them, Polymer B is in the outermost layer, and the outermost layer area is 20% of the total cross-sectional area. The raw yarn tenacity is 19.7. A tubular knitted fabric was made from the obtained fibers, and the anti-transparency performance of the obtained tubular knitted fabric is 94.8%, the dry-wet reflectance difference at a wavelength of 550 nanometers is 1.9%, it has ultraviolet resistance performance, and the light fastness passed the test.

[0064] Example 20 50 parts by weight of polyethylene terephthalate (PET) (Polymer A) containing 15.0 wt% of rutile-type TiO₂ particles and 50 parts by weight of semi-dull polyester (Polymer B) containing 0.3 wt% of TiO₂ particles are each pre-crystallized and dried to 50 ppm or less. Each is put into the A and B chip supply hoppers of a spinning machine for spinning, and false-twisting processing is carried out to produce long fibers with high anti-see-through performance. The fiber cross-section has a multi-layer concentric structure with 15 layers. Among them, Polymer B is on the outermost layer, and the outermost layer area is 20% of the total cross-sectional area. The raw yarn toughness is 17.1. A tubular knitted fabric is made from the obtained fibers, and the anti-see-through performance of the obtained tubular knitted fabric is 94.0%, the dry-wet reflectance difference at a wavelength of 550 nanometers is 2.8%, it has ultraviolet resistance performance, and the light fastness passes the test.

[0065] Example 21 20 parts by weight of polyethylene terephthalate (PET) (Polymer A) containing 60.0 wt% of rutile-type TiO₂ particles and 80 parts by weight of semi-dull polyester (Polymer B) containing 0.3 wt% of TiO₂ particles are each pre-crystallized and dried to 50 ppm or less. Each is put into the A and B chip supply hoppers of a spinning machine for spinning, and false-twisting processing is carried out to produce long fibers with high anti-see-through performance. The fiber cross-section has a multi-layer concentric structure with 3 layers. Among them, Polymer B is on the outermost layer, and the outermost layer area is 40% of the total cross-sectional area. The raw yarn toughness is 19.2. A tubular knitted fabric is made from the obtained fibers, and the anti-see-through performance of the obtained tubular knitted fabric is 94.3%, the dry-wet reflectance difference at a wavelength of 550 nanometers is 1.8%, it has ultraviolet resistance performance, and the light fastness passes the test.

[0066] Example 22 50 parts by weight of polyethylene terephthalate (PET) (Polymer A) containing 50.0 wt% of rutile-type TiO₂ particles and 50 parts by weight of semi-dull polyester (Polymer B) containing 0.3 wt% of TiO₂ particles are each pre-crystallized and dried to 50 ppm or less. Each is put into the A and B chip supply hoppers of a spinning machine for spinning, and false-twist processing is carried out to produce long fibers with high anti-transparency performance. The fiber cross-section has a multi-layer concentric structure with 3 layers. Among them, Polymer B is on the outermost layer, and the outermost layer area is 3% of the total cross-sectional area. The raw yarn tenacity is 17.1. A tubular knitted fabric is made from the obtained fibers, and the anti-transparency performance of the obtained tubular knitted fabric is 95.0%, the dry-wet reflectance difference at a wavelength of 550 nanometers is 1.0%, it has ultraviolet resistance performance, and the light fastness passes the test.

[0067] Example 23 50 parts by weight of polyethylene terephthalate (PET) (Polymer A) containing 70.0 wt% of rutile-type TiO₂ particles and 50 parts by weight of semi-dull polyester (Polymer B) containing 0.3 wt% of TiO₂ particles are each pre-crystallized and dried to 50 ppm or less. Each is put into the A and B chip supply hoppers of a spinning machine for spinning, and false-twist processing is carried out to produce long fibers with high anti-transparency performance. The fiber cross-section has a multi-layer concentric structure with 3 layers. Among them, Polymer B is on the outermost layer, and the outermost layer area is 20% of the total cross-sectional area. The raw yarn tenacity is 15.0. A tubular knitted fabric is made from the obtained fibers, and the anti-transparency performance of the obtained tubular knitted fabric is 97.3%, the dry-wet reflectance difference at a wavelength of 550 nanometers is 0.2%, it has ultraviolet resistance performance, and the light fastness passes the test.

[0068] Comparative Example 1 70 parts by weight of polyethylene terephthalate (PET) (Polymer A) containing 7.5 wt% of rutile-type TiO2 particles and 30 parts by weight of semi-dull polyester (Polymer B) containing 0.3 wt% of TiO2 particles are each pre-crystallized and dried to 50 ppm or less. Each is put into the A and B chip supply hoppers of a spinning machine for spinning, and false-twisting processing is carried out to produce long fibers with high anti-transparency performance. The fiber cross-section has a multi-layer concentric structure with 3 layers. Among them, Polymer B is on the outermost layer, and the outermost layer area is 20% of the total cross-sectional area, and the raw yarn toughness is 15.3. A tubular knitted fabric is made from the obtained fibers. The anti-transparency performance of the obtained tubular knitted fabric is 86.9%, the difference in dry and wet reflectance at a wavelength of 550 nanometers is 6.3%, it has no ultraviolet ray prevention performance, the discoloration after water immersion is remarkable, and the light fastness passes. When the inorganic particle content in Polymer A is lower than 10.0 wt%, even if the content of Polymer A in the composite fiber reaches 70 wt%, the anti-transparency effect of the composite fiber is poor, and the ultraviolet ray resistance performance and dry-wet color change and fading of the obtained textile are poor.

[0069] Comparative Example 2 45 parts by weight of polyethylene terephthalate (PET) (Polymer A) containing 30.0 wt% of rutile-type TiO₂ particles, 45 parts by weight of semi-dull polyester (Polymer B) containing 0.3 wt% TiO₂ particles, and 10 parts by weight of Polymer C containing 0.07 wt% TiO₂ particles were each pre-crystallized and dried to 50 ppm or less. Each was put into the chip supply hopper of a spinning machine for spinning, and false-twist processing was carried out to produce long fibers with high anti-see-through performance. The fiber cross-section is multi-layered and has 3 layers. Polymer A is in the innermost layer, Polymer B is in the middle layer, Polymer C is in the outermost layer, and the outermost layer area is 10% of the total cross-sectional area, and the raw yarn tenacity is 16.4. The obtained fibers were used to produce a tubular knitted fabric. The anti-see-through performance of the obtained tubular knitted fabric was 90.8%, the difference in dry and wet reflectance at a wavelength of 550 nanometers was 5.9%, and there was no ultraviolet ray blocking performance. The discoloration after water immersion was significant, and the light fastness passed. Even with a 3-layer cross-sectional structure, similar to ordinary core-sheath fibers, Polymer A with the highest inorganic particle content is arranged in the innermost layer of the fiber. Compared with Example 15 with the same inorganic particle content, the anti-see-through performance of the fiber is inferior, and the ultraviolet ray blocking performance and dry-wet color fading effect of the textile are also inferior.

[0070] Comparative Example 3 8 parts by weight of polyethylene terephthalate (PET) (Polymer A) containing 70.0 wt% of rutile-type TiO2 particles and 92 parts by weight of semi-dull polyester (Polymer B) containing 0.3 wt% TiO2 particles are each pre-crystallized and dried to 50 ppm or less. Each is put into the A and B chip supply hoppers of a spinning machine for spinning, and false-twist processing is carried out to produce long fibers with high anti-see-through performance. The fiber cross-section has a multi-layer concentric structure with 3 layers. Among them, Polymer B is on the outermost layer, and the outermost layer area is 20% of the total cross-sectional area, and the raw yarn tenacity is 19.9. A tubular knitted fabric is made from the obtained fibers. The anti-see-through performance of the obtained tubular knitted fabric is 86.4%, the difference in dry and wet reflectance at a wavelength of 550 nanometers is 12.4%, it has no ultraviolet protection performance, the discoloration after water immersion is significant, and the light fastness passes. When the content of inorganic particles from Polymer A in the composite fiber is less than 10 wt%, even when the content of inorganic particles in Polymer A reaches 70 wt%, the anti-see-through effect of the composite fiber is poor, and the ultraviolet resistance performance and dry and wet color change and fading of the obtained textile are poor.

[0071] Comparative Example 4 50 parts by weight of polyethylene terephthalate (PET) (Polymer A) containing 15 wt% of rutile-type TiO₂ particles and 50 parts by weight of semi-dull polyester (Polymer B) containing 5.5 wt% of TiO₂ particles are each pre-crystallized and dried to 50 ppm or less. Each is put into the A and B chip supply hoppers of a spinning machine for spinning, and yarn breakage and single-filament flow occurred during spinning. Also, when the obtained POY was subjected to false-twisting processing, yarn breakage occurred, and when passing through the guide block, a large amount of white powder accumulated and winding could not be carried out for a long time. The obtained false-twisted long fiber with high anti-transparency performance has a multi-layer concentric structure in the fiber cross-section, and the number of layers is 3. Among them, Polymer B is on the outermost layer, and the area of the outermost layer is 20% of the total cross-sectional area, and the raw yarn toughness is 13.7. Using the obtained fiber, a tubular knitted fabric was produced. The anti-transparency performance of the obtained tubular knitted fabric is 94.4%, the difference in dry and wet reflectance at a wavelength of 550 nanometers is 1.2%, it has ultraviolet protection performance, the discoloration after water infiltration is not significant, and the light fastness passed. When the inorganic particle content in Polymer B on the outermost layer is greater than 5.0 wt%, yarn breakage frequently occurs in the spinning process and the spinnability is poor.

[0072] Comparative Example 5 50 parts by weight of polyethylene terephthalate (PET) (Polymer A) containing 15 wt% of rutile-type TiO₂ particles and 50 parts by weight of semi-dull polyester (Polymer B) containing 0.3 wt% of TiO₂ particles are each pre-crystallized and dried to 50 ppm or less. Each is put into the A and B chip supply hoppers of a spinning machine for spinning, and false-twisting processing is carried out to produce long fibers with high anti-transparency performance. The fiber cross-section has a multi-layer concentric structure, and the number of layers is 20. Among them, Polymer B is on the outermost layer, and the area of the outermost layer is 20% of the total cross-sectional area. Abnormal cross-section formation occurred in the obtained fiber, and the raw yarn toughness was 15.4. Using the obtained fiber, a tubular knitted fabric was produced. The anti-transparency performance of the obtained tubular knitted fabric is 86.4%, the difference in dry and wet reflectance at a wavelength of 550 nanometers is 9.4%, and it has no ultraviolet protection performance. The discoloration after water infiltration is significant, and the light fastness passed. Due to too many layers, there is an abnormality in the formation of the fiber cross-section, and the anti-transparency performance, ultraviolet protection performance, and dry-wet discoloration effect are poor.

[0073] Comparative Example 6 10 parts by weight of polyethylene terephthalate (PET) (Polymer A) containing 80 wt% of rutile-type TiO₂ particles and 90 parts by weight of semi-dull polyester (Polymer B) containing 0.3 wt% of TiO₂ particles were each pre-crystallized and dried to 50 ppm or less. Each was put into the A and B chip supply hoppers of a spinning machine for spinning, and false-twisting processing was carried out to produce long fibers with high anti-transparency performance. The fiber cross-section has a multi-layer concentric structure with 3 layers. Among them, Polymer B is on the outermost layer, and the outermost layer area is 20% of the total cross-sectional area.

[0074] In the spinning process, due to the poor fluidity of Polymer A, abnormal cross-section formation occurred, and yarn breakage and single-filament flow occurred during spinning. Moreover, when the obtained POY was subjected to false-twisting processing, yarn breakage occurred, and when passing through the guide block, a large amount of white powder accumulated and winding could not be carried out for a long time. The raw yarn tenacity was 17.2, and the obtained fibers were made into a tubular knitted fabric. The obtained tubular knitted fabric had an anti-transparency performance of 95.9%, a dry-wet reflectance difference at a wavelength of 550 nanometers of 0.6%, had ultraviolet protection performance, had no significant discoloration after water immersion, and passed the light fastness test. When the inorganic particle content in Polymer A is higher than 70.0 wt%, yarn breakage frequently occurs in the spinning process and the spinnability is poor.

[0075] Comparative Example 7 75 parts by weight of polyethylene terephthalate (PET) (Polymer A) containing 10 wt% of rutile-type TiO₂ particles and 25 parts by weight of semi-dull polyester (Polymer B) containing 0.3 wt% of TiO₂ particles were pre-crystallized respectively and dried to 50 ppm or less. Each was put into the A and B chip supply hoppers of a spinning machine for spinning, and false twisting was carried out to produce long fibers with high anti-transparency performance. The fiber cross-section has a multi-layer concentric structure with 3 layers. Among them, Polymer B is in the outermost layer, and the outermost layer area is 20% of the total cross-sectional area. Since the tenacity of the raw yarn was too small at 12.7, yarn breakage and single-filament flow occurred in the spinning process. Also, yarn breakage occurred similarly in the false twisting process, and the processability was poor. The obtained fibers were made into tubular knitted fabrics. The obtained tubular knitted fabrics had an anti-transparency performance of 94.9%, a dry-wet reflectance difference at a wavelength of 550 nanometers of 1.2%, had ultraviolet protection performance, and passed the light fastness test. When the content of Polymer A in the composite fiber is higher than 70%, the tenacity of the fiber is small and cannot meet the requirements of normal use.

[0076]

Table 1

[0077]

Table 2

Claims

1. In the cross-section of a single filament of a multilayer laminated cross-section composite fiber, it has a multilayer structure in which two types of components are alternately laminated in 3 to 15 layers. The outermost layer of the multilayer cross-section structure is made of polymer B with an inorganic particle content of 5.0 wt% or less. At least one layer in the composite fiber is made of polymer A with an inorganic particle content of 10.0 to 70.0 wt%, and the polymer A is 10 to 70 wt% of the entire composite fiber. The inorganic particles are titanium oxide, calcium carbonate, barium sulfate, zinc oxide, silicon dioxide, or boron nitride. The polymer A and the polymer B are polymers of the same system selected from the group consisting of polyester, polyamide, and polypropylene. A multilayer laminated cross-section composite fiber characterized by the above.

2. The multilayer laminated cross-section composite fiber according to claim 1, wherein the content of inorganic particles from polymer A in the composite fiber is 7.0 to 30.0 wt%.

3. The multilayer laminated cross-section composite fiber according to claim 1 or 2, characterized in that in the cross-section of a single filament of the fiber, it has a multilayer structure in which polymer A and polymer B are alternately laminated in 3 to 9 layers.

4. The multilayer laminated cross-section composite fiber according to claim 1 or 2, wherein the content of inorganic particles in polymer A is 15 to 60 wt%.

5. The multilayer laminated cross-section composite fiber according to claim 1 or 2, characterized in that the area of the outermost layer of the multilayer laminated cross-section structure is 5 to 30% of the total cross-sectional area of the single filament.

6. The multilayer laminated cross-section composite fiber according to claim 1 or 2, characterized in that the absolute value of the difference in reflectance of visible light with a wavelength of 550 nanometers in the dry and wet states of the composite fiber is less than 5.0%.

7. The multilayer laminated cross-section composite fiber according to claim 1 or 2, characterized in that the toughness of the composite fiber is 15.0 or more.

8. A textile made of the multilayer laminated cross-section composite fiber according to claim 1.

9. The textile according to claim 8, characterized in that the absolute value of the difference in reflectance of visible light at 550 nanometers in the dry and wet states is less than 5.0%.

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