A fully dull fine denier DTY fiber and its preparation method

Abstract

The object of the present invention is to provide a fully dull fine denier DTY fiber with good mechanical properties and processing properties and a preparation method thereof. This fully dull fine denier DTY fiber includes a modified body. The modified body has a core-shell structure and includes delustering agent particles, a silicon layer wrapped outside the delustering agent particles, and an aluminum layer wrapped outside the silicon layer. The delustering agent particles include titanium dioxide, the silicon layer includes silicon oxide and is doped with calcium ions and sodium ions, and the aluminum layer includes aluminum oxide. By calcium ions occupying the active sites on the surface of titanium dioxide, the activity of titanium dioxide degrading polyester is reduced, the content of small molecule short-chain polyester in the polyester melt is reduced, the polyester melt maintains good viscosity, thereby reducing the spinning difficulty of the polyester melt, and making the fully dull fine denier DTY fiber obtained by spinning have high mechanical strength.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of new industrial materials, and particularly to a fully dull fine denier DTY fiber and a preparation method thereof. Background Art

[0002] A fully dull fiber refers to a fiber with a matte surface effect, which can reduce the reflection and flashing on the fiber surface, usually achieved by adding a relatively high content of titanium dioxide in chemical fibers. For chemical fibers without adding a delustering agent, the macromolecular chains inside the fiber are arranged regularly and the surface is smooth. When light such as visible light irradiates on the fabric surface, it will produce a very strong reflection, resulting in a dazzling gloss, which is contrary to the comfortable visual sense of the human eye. To solve this problem, the composition or structure of synthetic fibers can be improved. Usually, a certain amount of functional inorganic powder with a large refractive index difference from the fiber-forming polymer is added to the synthetic fiber to prepare semi-dull or fully dull products. Such dull fibers not only maintain the comfortable and soft texture of natural fibers but also exhibit the advantages of synthetic fibers in mechanical properties and other aspects, and at the same time meet people's expectations for the functionalization of synthetic fibers. With the continuous emergence of new processes, new technologies, and new products, the dull fiber market is also moving forward towards higher goals. The most intuitive manifestation is that there are a large number of dull fiber products on the market, too numerous to enumerate.

[0003] The key to the preparation of fully dull fibers lies in uniformly dispersing the inorganic nano powder with dulling function inside and on the surface of the fibers. From the research and development process of dull fibers, the masterbatch method is one of the main methods for the preparation of fully dull fibers. The masterbatch method is to feed the delustering agent, pure resin chips, and auxiliary raw materials into a twin-screw extruder according to a certain ratio. The materials are melted, blended, extruded, pelletized and other processes to prepare a high-concentration dull masterbatch that meets the production and use requirements. Then, according to the use requirements of related products, the masterbatch and pure chips are fed, mixed, and spun; or the masterbatch is added to the polyester melt, mixed, and spun to finally obtain fully dull fibers.

[0004] However, during the preparation of the masterbatch, due to titanium dioxide at high temperatures, the electrons in its valence band are excited and transition to the empty conduction band, forming electron-hole pairs with strong redox properties, resulting in its strong activity. This can cause thermal degradation of the polyester macromolecules, leading to a significant reduction in the intrinsic viscosity of the masterbatch. The masterbatch contains a large amount of low-molecular-weight polyester. At the same time, during the fiber preparation process, the friction between the fiber and mechanical components can cause wear on the fiber surface, resulting in the generation of white powder. A large amount of low-molecular-weight polyester will exacerbate this phenomenon, leading to an increase in the generation of white powder during the spinning process, causing fiber floating and breakage, and further resulting in a significant decline in the mechanical properties of the fully dull fiber. In addition, a large amount of white powder will also cause nozzle blockage and have an adverse impact on oiling, winding, and twisting, which will increase the difficulty of spinning. Due to the influence of multiple factors, the fully dull fine denier DTY fiber cannot meet the requirements of post-processing. Summary of the Invention

[0005] The purpose of the present invention is to provide a fully dull fine denier DTY fiber with good mechanical properties and processing performance and its preparation method.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A fully dull fine denier DTY fiber, comprising a modified body, the modified body having a core-shell structure, including:

[0008] Matting agent particles, including titanium dioxide;

[0009] A silicon layer, wrapped around the outer layer of the matting agent particles, including silicon oxide, calcium ions, and sodium ions;

[0010] An aluminum layer, wrapped around the outer layer of the silicon layer, including aluminum oxide.

[0011] Optionally, the fully dull fine denier DTY fiber is prepared by mixing and melting a masterbatch and a polyester matrix. The masterbatch includes a modified body and bright polyester. The intrinsic viscosity of the masterbatch is 0.47 dL / g - 0.50 dL / g, the moisture content of the masterbatch is not more than 30 ppm, and the content of the matting agent particles in the fiber is 2.0 wt% - 2.2 wt%.

[0012] Optionally, the single filament fineness of the fiber is 0.7 dtex - 1.0 dtex, the breaking strength ≥ 3.50 cN / dtex, the breaking elongation is 22.0% ± 2.0%, the linear density deviation rate ≤ 2.0%, the breaking strength CV value ≤ 3.8%, the breaking elongation CV value ≤ 8.0%, the crimp shrinkage rate is 10.5 - 12.0%, the boiling water shrinkage rate is 3.0% - 3.6%, the full bobbin rate ≥ 98%, the crimp stability is 75% - 85%, and the extinction degree ≥ 3.80.

[0013] The present invention also provides a method for preparing the above-mentioned full dull fine denier DTY fiber, including:

[0014] Disperse the titanium dioxide in deionized water, add a first pH regulator to obtain a slurry with a pH value of 10 - 11;

[0015] Heat the slurry to a preset temperature, dissolve sodium silicate and a calcium source in the slurry, add a second pH regulator to make the pH value of the slurry 9.3 - 9.5, and after aging, centrifuge, dry and grind the slurry to obtain an intermediate. The preset temperature is 80°C - 85°C, and the calcium source is a soluble calcium salt or calcium hydroxide;

[0016] Disperse the intermediate in deionized water to obtain a dispersion, dissolve sodium aluminate in the dispersion and add a third pH regulator to adjust the pH value to 8.9 - 9.1, and after aging, centrifuge, dry and grind to obtain the modified body;

[0017] Mix the modified body, bright polyester and antioxidant to obtain a mixed powder and perform a drying treatment. Melt the mixed powder and extrude and pelletize it at an extrusion temperature to obtain a masterbatch;

[0018] Mix the masterbatch with a polyester matrix and melt-spin to prepare the full dull fine denier DTY fiber.

[0019] Optionally, the concentration of titanium dioxide in the slurry is 20wt% - 25wt%, and the calcium source is calcium hydroxide.

[0020] Optionally, the mass of sodium silicate is 1.0 - 1.2% of the mass of titanium dioxide, the mass of the calcium source is 0.20% - 0.25% of the mass of titanium dioxide, and the mass of sodium aluminate is 2.5% - 3.0% of the mass of titanium dioxide.

[0021] Optionally, at least one salt substance is included in the first pH regulator, the second pH regulator and the third pH regulator.

[0022] Optionally, the first pH regulator is sodium hexametaphosphate, the second pH regulator is sulfuric acid, and the third pH regulator is sulfuric acid.

[0023] Optionally, the mass ratio of the modified body to the bright polyester is 1:(1 - 1.5), the mass of the antioxidant is 0.05% - 0.08% of the total mass of the bright polyester, and the extrusion temperature is 260°C - 270°C.

[0024] Optionally, the step of mixing the masterbatch with the polyester matrix and melt-spinning to prepare the full dull fine denier DTY fiber includes:

[0025] Mix the masterbatch with the polyester matrix, melt the mixture and perform spinning to obtain POY filaments;

[0026] Perform false twist texturing on the POY filaments and combine them to obtain the full dull fine denier DTY fibers;

[0027] The process parameters of the spinning are as follows: the extrusion temperature is 280°C - 290°C, the cooling air temperature is 20°C - 25°C, and the winding speed is 2800 m / min - 3000 m / min;

[0028] The process parameters of the false twist texturing are as follows: the spinning speed is 550 m / min - 600 m / min, the draw ratio is 1.55 - 1.63, the temperature of the first heating box is 230°C - 240°C, the temperature of the second heating box is 125°C - 135°C, and the D / Y ratio is 1.9 - 2.0.

[0029] According to the first aspect of the present invention, the surface of titanium dioxide is coated with silicon oxide and aluminum oxide. The chemically inert oxide film shields the chemically active sites of titanium dioxide, reducing the thermal degradation of polyester during the preparation of the titanium dioxide masterbatch. Since calcium ions and sodium ions can adsorb on the surface of titanium dioxide, they can occupy the active sites on the surface of titanium dioxide, thereby causing the catalytic inactivation of titanium dioxide and reducing the coordination ability of titanium in titanium dioxide to the carbonyl oxygen in polyester, which inhibits the activity of the titanium dioxide catalyst and is beneficial to the processing and preparation of the titanium dioxide masterbatch. To achieve the coating of silicon oxide and aluminum oxide, it is necessary to form a film of silicic acid and meta-aluminum acid through a solution method. Since too low a solute content will result in a low protective force for the active sites and too high a solute content will cause the solute to crystallize and be difficult to form a film, a two-layer different oxide shell is used for protection. Both silicon oxide and aluminum oxide can be prepared by ion dehydration, which is more suitable for forming a shell and is easy to obtain, with a lower cost and is more suitable for this system. In a core-shell structure with double-layer or multi-layer coating, the second layer and the outer film layer are often mainly reticular films. The silicon oxide molecule has a tetrahedral structural unit, and the silicon layer composed of silicon oxide has a dense three-dimensional reticular structure with strong anti-permeability ability. The aluminum oxide molecule has an octahedral structural unit, and the oxygen atoms coplanar between molecules are connected to form a planar layered structure with strong corrosion resistance. Forming a reticular aluminum layer outside the dense silicon layer is beneficial to improving the protection and isolation effect on titanium dioxide.

[0030] Furthermore, the intrinsic viscosity of the masterbatch will directly affect the mechanical properties and processing properties of the fiber filaments, and thus affect the qualification rate, durability and service life of the product.

[0031] According to the second aspect of the present invention, when the pH value of the slurry is 10 - 11 and the temperature is the preset temperature, sodium silicate and calcium source have relatively high solubility in deionized water. When the pH value of the slurry is converted to 9.3 - 9.5, sodium silicate is gradually converted into silicic acid during the aging process, and sodium ions and calcium ions are ionized in the solution. The sodium ions and calcium ions are adsorbed on the surface of titanium dioxide, and silicic acid adheres to titanium dioxide and precipitates. After centrifugal dehydration, silicic acid is converted into silicon dioxide, and sodium ions and calcium ions are doped therein to form a thin-film-like silicon layer. When the pH value of the dispersion liquid is 8.9 - 9.1, sodium aluminate is converted into aluminum hydroxide and adheres to the surface of the intermediate. After centrifugal drying, aluminum hydroxide is dehydrated and converted into aluminum oxide to form an aluminum layer, obtaining a modified body. The modified body is mixed with bright polyester and antioxidant and then melt-plasticized to form a masterbatch. Through the protection of the silicon film and aluminum film, the contact between titanium dioxide and polyester can be reduced, and the activity of titanium dioxide in degrading polyester can be decreased. The antioxidant can reduce the coordination ability of titanium in titanium dioxide to the carbonyl oxygen in polyester, further inhibiting the catalytic activity of titanium dioxide, which is beneficial to the processing and preparation of the titanium dioxide masterbatch.

[0032] Furthermore, by restricting the concentration of titanium dioxide in the slurry, it helps the full dispersion of titanium dioxide and the adhesion of the silicon layer and aluminum layer. Using calcium hydroxide as the calcium source, without introducing other elements and ions except calcium ions, has less impact on the system and helps the stability of the reaction system.

[0033] Furthermore, by defining the masses of sodium silicate, calcium source, and sodium aluminate, it helps the sodium ions and calcium ions to fully occupy the active sites of titanium dioxide, and helps to form silicon dioxide and aluminum oxide with a thin-film-like shape and a high coverage rate, which is beneficial to improving the mechanical properties and processing properties of the masterbatch.

[0034] Furthermore, using salt substances as pH regulators has a buffering effect, which is beneficial to the accuracy of pH adjustment and thus beneficial to the progress of the reaction.

[0035] Furthermore, sodium hexametaphosphate is easily soluble in water. As a salt of a strong base and a weak acid, it has a strong buffering effect and can form soluble complexes with calcium ions, etc. This helps to adjust the metal ion concentration in the solution, thereby affecting the pH value. In addition, the hydrolysis of sodium hexametaphosphate is irreversible, and the degree of hydrolysis is related to temperature and pH value, which provides the possibility for precise control of the pH value. Using sulfuric acid to adjust the pH has strong stability and is easily soluble, with good universality.

[0036] Furthermore, by defining the mass ratios of titanium dioxide and antioxidant to bright polyester, it helps to control the intrinsic viscosity of the masterbatch, and thus improve the processing properties of the masterbatch.

[0037] The above description is only an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and be implemented in accordance with the content of the specification, the following describes in detail with reference to the preferred embodiments of the present invention and the accompanying drawings. Description of the Drawings

[0038] Figure 1 It is a schematic structural diagram of the modified body in the present invention;

[0039] Figure 2 It is a flowchart of the preparation method of the full dull fine denier DTY fiber in the present invention. Detailed Embodiments

[0040] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work shall fall within the scope of protection of the present invention.

[0041] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0042] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0043] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0044] Titanium dioxide is a polycrystalline inorganic compound, which has tetragonal rutile and anatase types, and brookite type with properties between the two. Titanium dioxide is a wide bandgap semiconductor, and its valence band is formed by the hybridization of oxygen 2p orbital and iron 3d orbital. When the energy is greater than or equal to the bandgap width, titanium dioxide has a certain catalytic activity. At high temperatures, the electrons in the valence band of titanium dioxide are excited to jump to the empty conduction band, forming electron-hole pairs with strong redox. The electrons can be captured by the oxygen molecules in the system to form superoxide radicals, and the holes can oxidize the water molecules in the system to form hydroxyl radicals. Superoxide radicals and hydroxyl radicals are very active and can cause thermal degradation of polyester macromolecules. Although the catalytic activity of titanium dioxide is not high, when preparing titanium dioxide masterbatch, the content of titanium dioxide is as high as 50%, which makes the thermal degradation of polyester very serious, resulting in a serious decrease in the intrinsic viscosity of the masterbatch. At present, the intrinsic viscosity of titanium dioxide masterbatch is usually around 0.25dL / g-0.27dL / g, which is much lower than the polyester melt viscosity of 0.64dL / g-0.67dL / g. At present, the titanium dioxide content in semi-dull polyester fiber is usually 0.2%-0.25%, while the titanium dioxide content in full-dull polyester fiber is usually 2.0%-2.5%. When preparing full-dull polyester fiber by masterbatch method, the addition amount of titanium dioxide in the masterbatch is as high as 4%-5%, which will cause a large amount of low molecular weight polyester to be mixed in the masterbatch, which has a great impact on the fluidity of the masterbatch melt. At the same time, low molecular weight polyester has low flow viscosity and is very easy to migrate to the surface of the fiber during the preparation of polyester fiber. Low molecular weight polyester has poor mechanical properties. When the fiber contacts relevant parts of the equipment such as oil nozzle and friction disk, a large amount of white powder is generated due to friction, which has an adverse effect on oiling, winding and twisting.

[0045] Since titanium dioxide itself has lattice defects and is a wide bandgap semiconductor and is chemically active, a chemically inert oxide film can be coated on the surface of titanium dioxide to shield its chemically active points. The most common coating materials for titanium dioxide surface treatment are silicon oxide and aluminum oxide. Coating the surface with a silicon oxide film can significantly improve its weather resistance; coating the surface with an aluminum oxide film can improve the dispersibility of the application system. However, surface coating with silicon oxide and aluminum oxide still cannot completely cover the surface of titanium dioxide. In the prior art, the percentage of Ti atoms on the surface of titanium dioxide is 25%-26%, and the percentage of Ti atoms on the surface of titanium dioxide coated with silicon oxide and aluminum oxide is 13%-18%.

[0046] In order to reduce the activity of titanium dioxide, the inventors explored the substances and methods for coating the surface of titanium dioxide. At present, it is difficult to further reduce the activity of titanium dioxide because it is difficult to achieve complete coating of Ti atoms by the coating substance. When the addition amount of sodium metaaluminate reaches a certain value, part of the sodium metaaluminate crystallizes and it is impossible to further reduce the percentage content of Ti atoms in the surface of the coated titanium dioxide. The inventors found that cations can adsorb on the anionic radicals generated on the surface of Ti atoms, thereby reducing the activity of titanium dioxide. Based on this, the inventors doped various cations in the coating substance to explore the ability of different cations to reduce the activity of titanium dioxide. Through experimental research, it was found that calcium ions can specifically adsorb and combine with the anionic radicals generated by Ti atoms at high temperature, achieving the purpose of inhibiting the degradation of polyester by titanium dioxide.

[0047] Please refer to Figure 1 , the full dull fine denier DTY fiber protected by this invention application includes a modified body, and the modified body has a core-shell structure, including delustering agent particles 1, a silicon layer 2 wrapped outside the delustering agent particles 1, and an aluminum layer 3 wrapped outside the silicon layer 2. The delustering agent particles 1 include titanium dioxide, the silicon layer 2 includes silicon oxide and is doped with calcium ions 21 and sodium ions, and the aluminum layer 3 includes aluminum oxide.

[0048] Silicon oxide and aluminum oxide are used to coat the surface of titanium dioxide. The chemically inert oxide film layer shields the chemical active sites of titanium dioxide, reducing the thermal degradation of polyester during the preparation of titanium dioxide masterbatch. Since calcium ions 21 and sodium ions can adsorb on the surface of titanium dioxide, they can occupy the active sites on the surface of titanium dioxide, thereby causing the catalytic inactivation of titanium dioxide, reducing the coordination ability of titanium in titanium dioxide to the carbonyl oxygen in polyester, and playing an inhibitory role in the activity of the titanium dioxide catalyst, which is beneficial to the processing and preparation of titanium dioxide masterbatch. To achieve the coating of silicon oxide and aluminum oxide, it is necessary to form a film of silicic acid and metaaluminum acid through a solution method. Since too low a solute amount will result in a low protection force for the active sites and too high a solute amount will result in difficulty in film formation due to solute crystallization, two different oxide shell layers are used for protection. Both silicon oxide and aluminum oxide can be prepared by ion dehydration, are more suitable for forming shell layers, are easy to obtain, have a lower cost, and are more suitable for this system. The silicon oxide molecule has a tetrahedral structural unit, and the silicon layer 2 composed of silicon oxide has a dense three-dimensional network structure with strong anti-permeability ability. The aluminum oxide molecule has an octahedral structural unit, and the oxygen atoms coplanar between molecules are connected to each other to form a planar layered structure with strong corrosion resistance. Forming the aluminum layer 3 outside the silicon layer 2 is beneficial to improving the protection and isolation effect on titanium dioxide. At the same time, it is beneficial to the dispersion of the delustering agent in bright polyester.

[0049] In some embodiments, the full dull fine denier DTY fiber is prepared by melt blending a masterbatch and a polyester matrix. The masterbatch includes a modifier and a highly bright polyester wrapped around the modifier. The intrinsic viscosity of the masterbatch is 0.47 dL / g - 0.50 dL / g, and can be, for example, 0.47 dL / g, 0.48 dL / g, 0.49 dL / g, or 0.50 dL / g. The intrinsic viscosity of the masterbatch directly affects the mechanical properties and processing properties of the fiber filaments. Limiting the intrinsic viscosity of the masterbatch helps improve the qualification rate, durability, and service life of the fiber. The moisture content of the masterbatch is not more than 30 ppm, and can be, for example, 30 ppm, 29 ppm, 28 ppm, 25 ppm, 20 ppm, or 10 ppm. The content of the matting agent particles 1 in the fiber is 2.0 wt% - 2.2 wt%, and can be, for example, 2.0 wt%, 2.1 wt%, or 2.2 wt%. The content of the matting agent particles 1 in the fiber directly affects the matting effect of the fiber. If the content of the matting agent particles 1 is too high, it will have an adverse effect on the processing properties and mechanical properties of the fiber. If the content of the matting agent particles 1 is too low, the fiber will not achieve the full dull effect.

[0050] In some embodiments, the filament fineness of the fiber is 0.7 dtex - 1.0 dtex, and can be, for example, 0.7 dtex, 0.8 dtex, 0.9 dtex, or 1.0 dtex; the breaking strength ≥ 3.50 cN / dtex, and can be, for example, 3.50 cN / dtex, 3.60 cN / dtex, 3.70 cN / dtex, or 3.80 cN / dtex; the elongation at break is 22.0% ± 2.0%, and can be, for example, 20.0%, 21.0%, 22.0%, 23.0%, or 24.0%; the linear density deviation rate ≤ 2.0%, and can be, for example, 1.2%, 1.4%, 1.8%, or 2.0%; the CV value of the breaking strength ≤ 3.8%, and can be, for example, 2.8%, 3.0%, 3.4%, or 3.8%; the CV value of the elongation at break ≤ 8.0%, and can be, for example, 6.0%, 7.0%, 7.5%, or 8.0%; the crimp shrinkage rate is 10.5% - 12.0%, and can be, for example, 10.5%, 11.0%, 11.5%, or 12.0%; the boiling water shrinkage rate is 3.0% - 3.6%, and can be, for example, 3.0%, 3.2%, 3.4%, or 3.6%; the full bobbin rate ≥ 98%, and can be, for example, 98%, 98.4%, 98.8%, or 99%; the crimp stability is 75% - 85%, and can be, for example, 75%, 78%, 82%, or 85%; the degree of dullness ≥ 3.80, and can be, for example, 3.80, 3.90, 4.00, or 4.20.

[0051] The present invention also claims the preparation method of the above-mentioned full dull fine denier DTY fiber, including:

[0052] S1. Disperse titanium dioxide in deionized water, add the first pH regulator to obtain a slurry with a pH value of 10 - 11. The pH value of the slurry can be, for example, 10, 10.2, 10.4, 10.6, 10.8, or 11.

[0053] S2. Heat the slurry to a preset temperature, dissolve sodium silicate and calcium source in the slurry, add the second pH regulator to make the pH value of the slurry 9.3 - 9.5, which can be, for example, 9.3, 9.4, or 9.5. After aging, centrifuge, dry, and grind the slurry to obtain an intermediate. The preset temperature is 80°C - 85°C, which can be, for example, 80°C, 81°C, 82°C, 83°C, 84°C, or 85°C. The calcium source is a soluble calcium salt or calcium hydroxide, and the aging time is 2 h - 3 h, which can be, for example, 2 h, 2.5 h, or 3 h.

[0054] S3. Disperse the intermediate in deionized water to obtain a dispersion with a mass concentration of 20 wt% - 25 wt%, which can be, for example, 20 wt%, 23 wt%, or 25 wt%. Dissolve sodium metaaluminate in the dispersion and add the third pH regulator to adjust the pH value to 8.9 - 9.1, which can be, for example, 8.9, 9.0, or 9.1. After aging, centrifuge, dry, and grind to obtain a modified body.

[0055] S4. Mix the modified body, bright polyester, and antioxidant to obtain a mixed powder and perform a drying treatment. Melt the mixed powder and extrude and pelletize it at the extrusion temperature to obtain masterbatch.

[0056] S5. Mix the masterbatch with a polyester matrix and perform melt spinning to prepare a fully dull fine denier DTY fiber.

[0057] When the pH value of the slurry is 10 - 11 and the temperature is the preset temperature, sodium silicate and calcium source have a high solubility in deionized water. When the pH value of the slurry is converted to 9.3 - 9.5, sodium silicate gradually converts to silicic acid during aging, and sodium ions and calcium ions 21 ionize in the solution. Sodium ions and calcium ions 21 adsorb on the surface of titanium dioxide, and silicic acid adheres to titanium dioxide and precipitates. After centrifugal dehydration, silicic acid is converted to silicon dioxide, and sodium ions and calcium ions 21 are doped therein to form a film-like silicon layer 2. When the pH value of the dispersion is 8.9 - 9.1, sodium metaaluminate is converted to aluminum hydroxide and adheres to the surface of the intermediate. After centrifugal drying, aluminum hydroxide is dehydrated and converted to alumina to form an aluminum layer 3, obtaining a modified body. The modified body is mixed with bright polyester and antioxidant and then melt - plastically formed into a masterbatch. Through the protection of the silicon film and aluminum film, the contact between titanium dioxide and polyester can be reduced, and the activity of titanium dioxide degrading polyester can be decreased. The antioxidant can reduce the coordination ability of titanium in titanium dioxide to the carbonyl oxygen in polyester, further inhibiting the catalytic activity of titanium dioxide, which is beneficial to the processing and preparation of titanium dioxide masterbatch.

[0058] In some embodiments, the concentration of titanium dioxide in the slurry is 20 wt% - 25 wt%, for example, it can be 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt% or 25 wt%, which helps the titanium dioxide to be fully dispersed and facilitates the attachment of silicic acid, sodium ions and calcium ions 21. The calcium source is calcium hydroxide, which reduces the types of anions introduced and helps the stability of the reaction system.

[0059] In some embodiments, the mass of sodium silicate is 1.0% - 1.2% of the mass of titanium dioxide, for example, it can be 1.0%, 1.05%, 1.1%, 1.15% or 1.2%; the mass of the calcium source is 0.20% - 0.25% of the mass of titanium dioxide, for example, it can be 0.20%, 0.21%, 0.22%, 0.23%, 0.24% or 0.25%; the mass of sodium aluminate is 2.5% - 3.0% of the mass of titanium dioxide, for example, it can be 2.5%, 2.6%, 2.7%, 2.8%, 2.9% or 3.0%. By defining the mass ratios of sodium silicate, the calcium source and sodium aluminate to titanium dioxide, it helps the sodium ions and calcium ions 21 to fully occupy the active sites of titanium dioxide, and helps to form silicon oxide and aluminum oxide in the form of a thin film with a high coverage, thereby improving the mechanical properties and processing properties of the masterbatch.

[0060] In some embodiments, at least one salt substance is included in the first pH regulator, the second pH regulator and the third pH regulator, which is beneficial to the accuracy of pH adjustment and thus beneficial to the progress of the reaction.

[0061] In some embodiments, the first pH regulator is sodium hexametaphosphate. Sodium hexametaphosphate is easily soluble in water and has a strong buffering effect as a salt of a strong base and a weak acid. It can form soluble complexes with calcium ions 21, etc., which helps to adjust the metal ion concentration in the solution and thus affects the pH value. In addition, the hydrolysis of sodium hexametaphosphate is irreversible and the degree of hydrolysis is related to temperature and pH value, which provides the possibility for precise control of the pH value. The second pH regulator and the third pH regulator are both sulfuric acid, which do not participate in chemical reactions and have good universality.

[0062] In some embodiments, the mass ratio of the modifier to the bright polyester is 1:(1 - 1.5), for example, it can be (1:1), (1:1.1), (1:1.2), (1:1.3), (1:1.4) or (1:1.5); the mass of the antioxidant is 0.05% - 0.08% of the total mass of the bright polyester, for example, it can be 0.05%, 0.06%, 0.07% or 0.08%; the extrusion temperature is 260°C - 270°C, for example, it can be 260°C, 262°C, 264°C, 266°C, 268°C or 270°C.

[0063] In some embodiments, step S5 includes:

[0064] S501. Mix the masterbatch with the polyester matrix, melt the mixture, and perform spinning to obtain POY filaments.

[0065] S502. Perform false twist texturing on the POY filaments and combine them to obtain fully dull fine denier DTY fibers.

[0066] Among them, the process parameters for the spinning process are as follows: the extrusion temperature is 280°C - 290°C, for example, it can be 280°C, 282°C, 284°C, 286°C, 288°C, or 290°C; the cooling air temperature is 20°C - 25°C, for example, it can be 20°C, 21°C, 22°C, 23°C, 24°C, or 25°C; the winding speed is 2800 m / min - 3000 m / min, for example, it can be 2800 m / min, 2850 m / min, 2900 m / min, 2950 m / min, or 3000 m / min.

[0067] The process parameters for the false twist texturing process are as follows: the spinning speed is 550 m / min - 600 m / min, for example, it can be 550 m / min, 560 m / min, 570 m / min, 580 m / min, 590 m / min, or 600 m / min; the draw ratio is 1.55 - 1.63, for example, it can be 1.55, 1.57, 1.59, 1.61, or 1.63; the temperature of the first heating box is 230°C - 240°C, for example, it can be 230°C, 232°C, 234°C, 236°C, 238°C, or 240°C; the temperature of the second heating box is 125°C - 135°C, for example, it can be 125°C, 127°C, 129°C, 131°C, 133°C, or 135°C; the D / Y ratio is 1.9 - 2.0, for example, it can be 1.9, 1.95, or 2.0.

[0068] Example 1:

[0069] Please refer to Figure 2 , the method for preparing fully dull fine denier DTY fibers shown in a preferred embodiment of this application includes:

[0070] S1. Disperse titanium dioxide in deionized water so that the mass concentration of titanium dioxide therein is 25 wt%, stir evenly, and then slowly add 0.5 mol / L of sodium hexametaphosphate to adjust the pH so that the pH value of the obtained slurry is 10.3.

[0071] S2. Heat the slurry to 83 °C, and add a sodium silicate solution with a concentration of 0.3 mol / L until the mass of sodium silicate is 1.1% of that of titanium dioxide. Then continue to add a calcium hydroxide solution with a concentration of 0.1 mol / L until the mass of calcium hydroxide is 0.25% of that of titanium dioxide. After stirring evenly, gradually adjust the pH value with 1.6 wt% sulfuric acid until the pH value of the obtained system is 9.47. After aging for 3 h, centrifuge, dry, and grind the obtained system to obtain a powdery intermediate product.

[0072] S3. Disperse the intermediate product in deionized water to obtain a dispersion with a mass concentration of 25 wt%. Add a sodium aluminate solution with a concentration of 0.6 mol / L until the mass of sodium aluminate is 2.7% of the mass of titanium dioxide in the dispersion. After stirring and mixing evenly, adjust the pH value again with 1.6 wt% sulfuric acid until the pH value of the obtained system is 9.02. After aging for 3 h again, centrifuge, dry, and grind the obtained system to obtain a powdery modified product.

[0073] S401. Mix the components in the ratio of modified product: bright polyester powder: triphenyl phosphate powder = 50:50:8. Control the temperature between 150 °C and 170 °C for drying treatment for 12 h, and then detect the moisture content of the mixed powder. When the moisture content is greater than or equal to 30 ppm, continue drying for 1 h until the moisture content is less than 30 ppm. In this example, the moisture content is 27 ppm.

[0074] S402. Put the dried mixed powder into a twin-screw extruder for melting and pelletizing. The temperature of the twin-screw is 260 °C - 270 °C, and the extrusion temperature is 265 °C to obtain masterbatch. The intrinsic viscosity of the obtained masterbatch is detected to be 0.49 dL / g.

[0075] S501. Mix the masterbatch and polyester matrix in a mass ratio of 1:19, melt them, and perform spinning treatment to obtain POY yarn. The process parameters of the spinning treatment are as follows: the extrusion temperature is 290 °C, the cooling air temperature is any value between 25 °C, and the winding speed is 2800 m / min.

[0076] S502. Perform false twist texturing treatment on the POY yarn and combine them to obtain full dull fine denier DTY fiber. Set the fineness of a single fiber to 1.0 dtex, and adjust the process parameters of the false twist texturing treatment as follows: the spinning speed is 550 m / min, the draw ratio is 1.55, the temperature of the first heating box is 240 °C, the temperature of the second heating box is 130 °C, and the D / Y ratio is 2.0.

[0077] During the preparation process of this example, less white dust is generated, and no problems such as floating single filaments and broken ends are found.

[0078] The obtained full dull fine denier DTY fibers were subjected to property tests. Their breaking strength was 3.86 cN / dtex, elongation at break was 22.9%, linear density deviation rate was 1.32%, breaking strength CV value was 3.0%, elongation at break CV value was 6.8%, crimp shrinkage rate was 11.4%, boiling water shrinkage rate was 3.0%, full bobbin rate was 98.7%, crimp stability was 81%, and extinction was 4.20.

[0079] The full dull fine denier DTY fibers prepared in the present invention have a good matte effect and excellent mechanical properties, and the spinning difficulty is low and the yield is high, which is conducive to cost savings.

[0080] Example 2:

[0081] The difference between this example and Example 1 is only that the set monofilament fineness in this example is 0.85 dtex. The breaking strength of the fibers obtained in this comparative example was 3.75 cN / dtex, elongation at break was 23.8%, linear density deviation rate was 1.46%, breaking strength CV value was 3.3%, elongation at break CV value was 7.2%, crimp shrinkage rate was 11.7%, boiling water shrinkage rate was 3.2%, full bobbin rate was 98.2%, crimp stability was 83%, and extinction was 4.12.

[0082] Comparative Example 1:

[0083] The difference between this comparative example and Example 1 is only that in this comparative example, titanium dioxide was directly mixed with bright polyester powder and triphenyl phosphate powder to prepare a masterbatch and fibers were prepared. The breaking strength of the fibers obtained in this comparative example was 3.0 cN / dtex, elongation at break was 24%, linear density deviation rate was 2.8%, breaking strength CV value was 5.8%, elongation at break CV value was 10.5%, crimp shrinkage rate was 9.3%, boiling water shrinkage rate was 4.8%, full bobbin rate was 87%, crimp stability was 73%, and extinction was 3.96. A large amount of white dust was generated during the spinning process, and the number of problems such as single floating filaments or broken ends occurred more frequently.

[0084] Comparing with the solution and data in Example 1, it can be seen that when the fineness is fixed, surface coating modification of titanium dioxide helps to reduce the catalytic activity of titanium dioxide, inhibit the thermal degradation of polyester caused by titanium dioxide, prevent the intrinsic viscosity of the titanium dioxide masterbatch from being too low and the mobile phase from being poor, helps to reduce the fiber processing difficulty, improve the fiber stability and the physical properties of the fibers.

[0085] Comparative Example 2:

[0086] The difference between this comparative example and Example 1 is only that calcium hydroxide is not added in step S2 of this comparative example. At this time, the silicon layer 2 on the outside of the matting agent particles 1 in the fiber only contains silicon oxide and a small amount of sodium ions. The breaking strength of the fiber obtained in this comparative example is 3.5 cN / dtex, the breaking elongation is 23%, the linear density deviation rate is 3.0%, the CV value of the breaking strength is 4.2%, the CV value of the breaking elongation is 9.8%, the crimp shrinkage rate is 10.2%, the boiling water shrinkage rate is 3.6%, the full bobbin rate is 92%, the crimp stability is 70%, and the matting degree is 3.88. There is more white dust generated during the spinning process, and there are problems of single filament floating or broken ends several times.

[0087] Comparing with the scheme and data in Example 1, it can be seen that the surface coating with only silicon oxide and aluminum oxide cannot completely coat the surface of titanium dioxide, and the addition of calcium ions 21 helps to further reduce the activity of titanium dioxide.

[0088] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0089] The above-described embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent should be subject to the appended claims.

Claims

1. A fully dull fine-denier DTY fiber, characterized in that: The invention comprises a modified body, wherein the modified body has a core-shell structure and comprises: Matting agent particles (1) comprising titanium dioxide; A silicon layer (2), wrapped around the outer layer of the matting agent particles (1), comprising silicon oxide, calcium ions (21) and sodium ions; The aluminum layer (3) is wrapped around the outer layer of the silicon layer (2) and comprises aluminum oxide.

2. The full-dull fine-denier DTY fiber according to claim 1, characterized in that: The fiber is prepared by melting and mixing a masterbatch and a polyester matrix, wherein the masterbatch includes the modified body and the highly glossy polyester, the intrinsic viscosity of the masterbatch is 0.47 dL / g-0.50 dL / g, the moisture content of the masterbatch is not more than 30 ppm, and the content of the matting agent particles (1) in the fiber is 2.0 wt%-2.2 wt%.

3. The full-dull fine-denier DTY fiber according to claim 2, characterized in that: The fiber has a single-filament fineness of 0.7 dtex-1.0 dtex, a breaking strength of ≥3.50 cN / dtex, an elongation at break of 22.0%±2.0%, a linear density deviation rate of ≤2.0%, a breaking strength CV value of ≤3.8%, a breaking elongation CV value of ≤8.0%, a curl shrinkage rate of 10.5%-12.0%, a boiling water shrinkage rate of 3.0%-3.6%, a full roll rate of ≥98%, a curl stability of 75%-85%, and a mattness of ≥3.

80.

4. A method for preparing the fully matte fine-denier DTY fiber as claimed in any one of claims 1 to 3, characterized in that: include: Dispersing the titanium dioxide in deionized water, adding a first pH adjuster, and obtaining a slurry with a pH value of 10-11; The slurry is heated to a preset temperature, and sodium silicate and a calcium source are dissolved in the slurry, a second pH adjuster is added to adjust the pH value of the slurry to 9.3-9.5, and the slurry is centrifugally dried and ground after aging to obtain an intermediate, the preset temperature is 80° C.-85° C., and the calcium source is a soluble calcium salt or calcium hydroxide; Dispersing the intermediate in deionized water to obtain a dispersion, dissolving sodium aluminate in the dispersion and adding a third pH adjuster to adjust the pH value to 8.9-9.1, aging, centrifugally drying and grinding to obtain the modified product; The modified product, the bright polyester and the antioxidant are mixed to obtain a mixed powder and dried, and the mixed powder is melted and extruded and granulated at an extrusion temperature to obtain a masterbatch; The master batch is mixed with a polyester matrix and then melt-spun to prepare the full-dull fine-denier DTY fiber.

5. The method for preparing the full-dull fine-denier DTY fiber according to claim 4, characterized in that: The concentration of titanium dioxide in the slurry is 20wt%-25wt%, and the calcium source is calcium hydroxide.

6. The method for preparing the full-dull fine-denier DTY fiber according to claim 5, characterized in that: The mass of the sodium silicate is 1.0%-1.2% of the mass of titanium dioxide, the mass of the calcium source is 0.20%-0.25% of the mass of titanium dioxide, and the mass of the sodium aluminate is 2.5%-3.0% of the mass of titanium dioxide.

7. The method for preparing the fully matte fine-denier DTY fiber according to claim 4, characterized in that: The first pH adjuster, the second pH adjuster and the third pH adjuster include at least one salt substance.

8. The method for preparing the fully matte fine-denier DTY fiber according to claim 7, characterized in that: The first pH adjuster is sodium hexametaphosphate, the second pH adjuster is sulfuric acid, and the third pH adjuster is sulfuric acid.

9. The method for preparing the full-dull fine-denier DTY fiber according to claim 4, characterized in that: The mass ratio of the modified body to the highly shiny polyester is 1:(1-1.5), the mass of the antioxidant is 0.05%-0.08% of the total mass of the highly shiny polyester, and the extrusion temperature is 260°C-270°C.

10. The method for preparing the full-dull fine-denier DTY fiber according to claim 4, characterized in that: The step of mixing the masterbatch with the polyester matrix and then melting and molding to form the full-dull fine-denier DTY fiber comprises: The masterbatch is mixed with the polyester matrix, melted, and spun to obtain POY yarn; The POY yarn is subjected to false twisting and deformation treatment and combined to obtain the full-dull fine-denier DTY fiber; The process parameters of the spinning process are: extrusion temperature is 280°C-290°C, cooling air temperature is 20°C-25°C, and winding speed is 2800m / min-3000m / min; The process parameters of the false twist texturing treatment are: spinning speed of 550m / min-600m / min, stretching multiple of 1.55-1.63, first heating box temperature of 230℃-240℃, second heating box temperature of 125℃-135℃, and D / Y ratio of 1.9-2.0.

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