A kind of full-dull polyester fiber and preparation method thereof

Abstract

The present invention relates to the field of polyester fibers, and in particular to a fully matte polyester fiber and a preparation method thereof. The fully matte polyester fiber comprises polyester, a doped polymer dispersed in the polyester, and titanium dioxide. The polyester and the doped polymer have different refractive indexes and poor compatibility, so that an interface exists between the polyester and the doped polymer. The doped polymer is spinnable and forms a filament together with the polyester during the spinning process, thereby forming a fiber comprising the polyester and the doped polymer. Since the refractive indexes of the polyester and the doped polymer are different, the light is refracted when it reaches the interface, thereby increasing the overall mattness of the fiber. Titanium dioxide is doped in the fiber to increase the overall mattness of the fiber, and the titanium dioxide attached to the surface of the fiber can make the surface of the fiber appear matte. The polyester, the doped polymer and the titanium dioxide are added in a blended manner, which helps to simplify the process.

Description

Technical Field

[0001] The invention relates to the field of polyester fibers, and in particular to a full-dull polyester fiber and a preparation method thereof. Background Art

[0002] Polyester fiber is a commonly used clothing fiber. Due to its regular shape, polyester fiber often has obvious reflection and glittering during use. In order to eliminate this phenomenon, people mix matting agents with absorption or reflection into the polymer melt during the polymerization or spinning process, so that the fiber has a matting effect.

[0003] At present, titanium dioxide has become the most commonly used matting agent due to its stable chemical properties and non-toxic and odorless properties. However, titanium dioxide will catalyze the degradation of polyester, resulting in a decrease in the mechanical properties of polyester fibers. The large amount of titanium dioxide added will make polyester fibers prone to problems such as floating single filaments and broken ends during spinning, which leads to generally poor mechanical properties of fully matte polyester fibers. Summary of the invention

[0004] The object of the present invention is to provide a full-dull polyester fiber with good mechanical properties and a preparation method thereof.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A fully matte polyester fiber comprises polyester, a doped polymer and titanium dioxide. The polyester and the doped polymer have different refractive indexes, the doped polymer has fiber-forming properties, and an interface exists when the doped polymer and the polyester are in contact in a molten state.

[0007] Optionally, the full-dull polyester fiber further comprises a compatibilizer, and the compatibilizer is used to improve the compatibility between the polyester and the doped polymer.

[0008] Optionally, the doped polymer is polypropylene, and the compatibilizer is polypropylene grafted with acrylic acid.

[0009] Optionally, the titanium dioxide and the polypropylene grafted acrylic acid are included, the content of the titanium dioxide is 1.7wt%-1.9wt% of the full-dull polyester fiber, the content of the polypropylene is 1.5wt%-2.0wt% of the polyester, the grafting rate of the polypropylene grafted acrylic acid is 2.5%-3.0%, and the content of the polypropylene grafted acrylic acid is 4.0wt%-5.0wt% of the polypropylene.

[0010] Optionally, the intrinsic viscosity of the polyester melt is 0.65 dL / g-0.70 dL / g, and the melt index of the polypropylene is 16 g / 10 min-20 g / 10 min.

[0011] Optionally, the fiber has a single fiber fineness of 1.0dtex-3.0dtex, a breaking strength ≥3.30cN / dtex, an elongation at break of 28%-32%, a network density of 11 / m-19 / m, a linear density deviation rate ≤1.0%, a breaking strength CV value ≤5.0%, a breaking elongation CV value ≤10.0%, and a boiling water shrinkage rate of 7.0%-8.0%.

[0012] Optionally, the fiber has a transmittance of 93.3-94.4 and a reflectance of 83.0-84.0 in a wavelength range of 400 nm to 700 nm.

[0013] In a second aspect, the present invention further provides a method for preparing the above-mentioned fully matte polyester fiber, comprising:

[0014] Weighing appropriate amounts of the doped polymer, the titanium dioxide and the polyester to obtain a spinning raw material;

[0015] The spinning raw materials are added into a screw for melting and filtered through a filter assembly, and then filaments are extruded and fully stretched and spun to obtain the fully matte polyester fiber.

[0016] Optionally, the parameters of the full-stretch spinning are:

[0017] Cooling temperature is 20℃-25℃;

[0018] The network pressure is 0.20MPa-0.30MPa;

[0019] The speed of one roller is 2200m / min-2300m / min;

[0020] The temperature of one roller is 80℃-90℃;

[0021] The speed of the second roller is 3300m / min-3400m / min;

[0022] The temperature of the second roller is 135℃-150℃;

[0023] The winding speed is 3230m / min-3310m / min.

[0024] Optionally, the replacement period of the filter component is 35 days to 40 days.

[0025] According to the first aspect of the present invention, there is a difference in the refractive index of polyester and doped polymer, and the doped polymer is dispersed in the polyester matrix as a dispersed phase, and there is an interface between the dispersed phase and the matrix. When light passes through the polyester and encounters the interface, the light is refracted, and the fiber presents an opaque state, that is, the extinction phenomenon. Titanium dioxide, as the most commonly used extinction agent, has excellent extinction performance and can improve the surface and overall extinction of polyester. Due to the existence of an interface between polyester and doped polymer, it can be judged that the compatibility between polyester and doped polymer is limited. The compatibility between the two phases of the blend often determines the performance of the polymer. Good compatibility makes the microscopic morphology of the blend more stable, the dispersion of the microscopic phase is better, and then the blend has excellent macroscopic properties. When the compatibility between polyester and doped polymer is low, the addition of too much doped polymer will make the material spinning too difficult and difficult to form fibers. Therefore, although the extinction can be improved only by refraction at the interface, it is difficult to achieve the effect of full extinction when the addition amount of doped polymer is limited. Although the refraction of light can achieve the extinction inside the polyester, it is difficult to reduce the extinction of the polyester surface. By adding titanium dioxide, the extinction of the polyester surface can be increased, and the extinction of the polyester as a whole can be further increased, thereby achieving a full extinction effect.

[0026] In addition, in the full matte spinning process, due to the high content of titanium dioxide, the pressure required for filtration gradually increases, and the fluidity of the spinning melt will seriously affect the speed of pressure increase. When the pressure reaches the limit bearing value of the filter component, the filter component needs to be replaced, which will waste a lot of costs. The doped polymer is introduced into the spinning melt in the present invention, which reduces the content of titanium dioxide and the pressure requirement during filtration, which helps to increase the service life of the filter component, thereby reducing the spinning cost.

[0027] Furthermore, due to the interface between polyester and doped polymer, i.e., poor compatibility, there are often a large number of holes and gaps at the interface, which will have a certain adverse effect on the fiber performance. By introducing a compatibilizer, the compatibility between polyester and doped polymer is improved, which helps to reduce the holes and gaps at the interface while maintaining the existence of the interface, thereby reducing the size of the dispersed phase, increasing the uniformity, and improving the adhesion of the interface between the two phases, reducing the interfacial tension, thereby stabilizing the overall morphology of the fiber, and improving the mechanical properties of the fiber while ensuring the extinction.

[0028] Furthermore, polypropylene belongs to the polyolefin polymer class and is a polymer with a relatively low density, excellent processing properties, mechanical properties and thermal stability. Due to differences in polarity and chemical structure, polypropylene and polyester have poor compatibility. Using polypropylene as a doped polymer can maintain stable chemical properties under the conditions of polyester processing technology, and has excellent mechanical properties, which helps to maintain the chemical inertness and mechanical properties of the fiber as a whole. Polypropylene grafted with acrylic acid introduces polar acrylic acid groups into the non-polar polypropylene chain, making it more compatible with both non-polar polypropylene and polar polyester, thereby reducing the interfacial tension between polypropylene and polyester, and increasing the interfacial bonding strength between polypropylene and polyester, thereby reducing the amount of holes and gaps at the interface, which helps to form a more uniform and stable blend structure and improve the overall performance of the material.

[0029] Furthermore, by properly proportioning the content of polypropylene and titanium dioxide, it is helpful to achieve the effect of matting while maintaining good mechanical properties of the fiber as a whole. The volume-increasing effect of polypropylene grafted with acrylic acid is related to its grafting rate. By adding an appropriate amount of polypropylene grafted with acrylic acid, it is helpful to improve the compatibility between polypropylene and polyester, and to improve the stability and mechanical properties of the fiber.

[0030] Furthermore, there are many types of polypropylene, and the viscosity varies greatly. High-viscosity polypropylene has poor spinnability, and blending with polyester will cause inconvenience to spinning. Limiting the intrinsic viscosity of the polyester melt and the melt index of the polypropylene helps to improve the spinnability of the mixture.

[0031] According to the second aspect of the present invention, doped polymer chips, polyester chips, extender chips and titanium dioxide powder are put into a screw together, physically mixed and melt-treated, and then filtered and spun, which simplifies the operation steps, simplifies the preparation process, helps to improve production efficiency, and saves time and labor costs.

[0032] Furthermore, during the spinning process, the filter assembly will gradually wear out due to long-term high-speed operation and friction. This wear will increase the roughness of the component surface, thereby affecting the uniformity and quality of spinning. Timely replacement of the filter assembly helps to improve the overall quality of the fiber.

[0033] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a flow chart of the method for preparing fully matte polyester fiber shown in Example 1 of the present invention. DETAILED DESCRIPTION

[0035] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are 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 cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0037] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" 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 a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0039] The method of preparing full matt polyester fiber by adding matt agent titanium dioxide is the prior art in this technical field. Titanium dioxide is a wide bandgap semiconductor, and its valence band is formed by the hybridization of the 2p orbital of oxygen and the 3d orbital of iron. When the energy is greater than or equal to the bandgap width, titanium dioxide has a certain catalytic activity. At high temperature, 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, and the electrons can be captured by the oxygen molecules in the system to form superoxide free radicals, and the holes can oxidize the water molecules in the system to form hydroxyl free radicals. Superoxide free radicals and hydroxyl free radicals are very active and can cause thermal degradation of polyester macromolecules, which will cause a large amount of polyester with shorter molecular chains to be doped in the polyester fiber, which will reduce the fluidity of the spinning melt and reduce the strength of the polyester fiber, thereby increasing the difficulty of the spinning operation and reducing the fiber quality. In addition, the full matte fiber has a large amount of titanium dioxide inorganic particles added, so its processing performance at each stage is very different from other products, and the different performance of the intermediate products at each stage also affects the quality and processing efficiency of the final product to varying degrees. The higher the titanium dioxide content, the better the matte effect, but the titanium dioxide is dispersed in the melt, and the titanium dioxide on the surface of the melt is easy to sublimate and agglomerate on the spinneret, causing floating single filaments and broken ends during the spinning process, increasing the difficulty of spinning. The higher the content, the greater the difficulty of spinning. In addition, since titanium dioxide particles are insoluble additives and are not wetted by the polymer melt, they can act as crystal nuclei during the crystallization process, thereby affecting the crystallization process, and the formed crystal nuclei are easy to become condensed particles, which finally makes it easy to produce hairy filaments or broken ends during spinning.

[0040] In order to solve the above problems, the inventor tried to find another matting agent with a higher matting effect to replace titanium dioxide, so as to reduce the impact of titanium dioxide on fiber performance. In the experiment, the inventor noticed that the interface formed between two substances with poor compatibility can achieve the effect of increasing the matting degree. The inventor dispersed another molten substance inside the molten polyester to form an interface inside the mixed melt, thereby improving the matting degree. However, this doping will affect the overall fiber-forming properties and reduce the spinnability of the mixed melt. In order to reduce this adverse effect, the inventor studied the melting point, refractive index and fiber-forming properties of various different polymers, and finally selected a doped polymer that can effectively improve the matting degree of polyester fibers.

[0041] The fully matte polyester fiber protected by the present invention comprises polyester, a doped polymer dispersed in the polyester, and titanium dioxide. The polyester and the doped polymer have different refractive indexes and poor compatibility, so that an interface exists between the polyester and the doped polymer. The doped polymer is spinnable and forms a filament together with the polyester during the spinning process, thereby forming a fiber comprising the polyester and the doped polymer. Since the refractive indexes of the polyester and the doped polymer are different, the light is refracted when it reaches the interface, thereby increasing the overall matte of the fiber. Titanium dioxide is doped in the fiber to increase the overall matte of the fiber, and the titanium dioxide attached to the surface of the fiber can make the surface of the fiber appear matte.

[0042] In some embodiments, the full matte polyester fiber further includes a compatibilizer for improving the compatibility between the polyester and the doped polymer. The compatibilizer can improve the compatibility between the polyester and the doped polymer, thereby improving the stability, integrity and mechanical strength of the fiber.

[0043] In some embodiments, the doped polymer is polypropylene, and the compatibilizer is polypropylene grafted acrylic acid. There is an interface between the doped polymer and the polyester. Since polyester is a highly polar substance, the doped polymer should be selected from non-polar substances. In addition, the selection of the doped polymer also depends on its spinnability. In the present invention, the doped polymer can be selected from polyamide and polypropylene, preferably polypropylene. In order to improve the compatibility between polypropylene and polyester, polypropylene grafted acrylic acid is selected as a compatibilizer to make the interface bond more closely.

[0044] In some embodiments, the content of titanium dioxide is 1.7wt%-1.9wt% of the full matte polyester fiber, for example, it can be 1.7wt%, 1.74wt%, 1.78wt%, 1.82wt%, 1.86wt% or 1.9wt%. The content of polypropylene is 1.5wt%-2.0wt% of the polyester, for example, it can be 1.5wt%, 1.6wt%, 1.7wt%, 1.8wt%, 1.9wt% or 2.0wt%. The reasonable ratio of titanium dioxide and polypropylene content helps to ensure the matte degree while making the fiber have excellent mechanical properties. The grafting rate of polypropylene grafted with acrylic acid is 2.5%-3.0%, for example, it can be 2.5wt%, 2.6wt%, 2.7wt%, 2.8wt%, 2.9wt% or 3.0wt%. The content of polypropylene grafted acrylic acid is 4.0wt%-5.0wt% of polypropylene, for example, it can be 4.0wt%, 4.2wt%, 4.4wt%, 4.6wt%, 4.8wt% or 5.0wt%. The capacity of polypropylene grafted acrylic acid is closely related to its grafting rate. Selecting polypropylene grafted acrylic acid with a suitable grafting rate and selecting the amount of polypropylene grafted acrylic acid added based on polypropylene can help ensure that the compatibility between polypropylene and polyester is moderate, thereby maintaining a high degree of matting while ensuring the integrity and stability of the fiber.

[0045] In some embodiments, the intrinsic viscosity of the polyester melt is 0.65 dL / g-0.70 dL / g, for example, 0.65 dL / g, 0.66 dL / g, 0.67 dL / g, 0.68 dL / g, 0.69 dL / g or 0.70 dL / g. The melt index of the polypropylene is 16 g / 10min-20 g / 10min, for example, 16 g / 10min, 17 g / 10min, 18 g / 10min, 19 g / 10min or 20 g / 10min. By limiting the fluidity and viscosity of the polypropylene and the polyester, the polypropylene and the polyester both maintain high spinnability.

[0046] In some embodiments, the monofilament fineness of the full-dull polyester fiber is 1.0 dtex-3.0 dtex, for example, 1.0 dtex, 2.0 dtex or 3.0 dtex. The breaking strength is ≥3.30 cN / dtex, for example, 3.30 cN / dtex, 3.50 cN / dtex, 3.65 cN / dtex or 3.70 cN / dtex. The breaking elongation is 28%-32%, for example, 28%, 29%, 30%, 31% or 32%. The network degree is 11 / m-19 / m, for example, 11 / m, 13 / m, 15 / m, 17 / m or 19 / m. The linear density deviation rate is ≤1.0%, for example, 1.0%, 0.9%, 0.8%, 0.7% or 0.5%. The breaking strength CV value is ≤5.0%, for example, it can be 5.0%, 4.8%, 4.5%, 4.0% or 3.7%. The breaking elongation CV value is ≤10.0%, for example, it can be 10.0%, 9.8%, 9.5%, 8.0% or 6.7%. The boiling water shrinkage is 7.0%-8.0%, for example, it can be 7.0%, 7.2%, 7.5%, 7.7% or 8.0%.

[0047] In some embodiments, the transmittance of the fully matte polyester fiber in the wavelength range of 400nm to 700nm is 93.3-94.4, for example, it can be 93.3, 93.5, 93.8, 94.1 or 94.4; the reflectivity is 83.0-84.0, for example, it can be 83.0, 83.2, 83.4, 83.6, 83.8 or 84.0, thereby achieving a fully matte effect.

[0048] See also Figure 1 The present invention also applies for protection of a method for preparing the above-mentioned fully matte polyester fiber, comprising:

[0049] S1. Weigh appropriate amounts of doped polymer, titanium dioxide and polyester to obtain spinning raw materials;

[0050] S2, adding the spinning raw materials into the screw to melt and filter through the filter assembly, extruding the filaments and performing full-stretching spinning to obtain full-dull polyester fibers.

[0051] Doped polymers and polyesters are usually made of sliced ​​raw materials, and titanium dioxide is usually made of titanium dioxide powder. Physically mixing and melting a variety of raw materials can meet the mixing requirements of the present invention, which helps to simplify the process and improve the preparation efficiency.

[0052] In some embodiments, the parameters of full-draw spinning are:

[0053] The cooling temperature is 20°C-25°C, for example, 20°C, 21°C, 22°C, 23°C, 24°C or 25°C;

[0054] The network pressure is 0.20MPa-0.30MPa, for example, 0.20MPa, 0.22MPa, 0.24MPa, 0.26MPa, 0.28MPa or 0.30MPa;

[0055] A roller speed is 2200 m / min-2300 m / min, for example, 2200 m / min, 2220 m / min, 2240 m / min, 2260 m / min, 2280 m / min or 2300 m / min;

[0056] The temperature of one roller is 80°C-90°C, for example, 80°C, 82°C, 84°C, 86°C, 88°C or 90°C;

[0057] The speed of the two rollers is 3300 m / min-3400 m / min, for example, 3300 m / min, 3320 m / min, 3340 m / min, 3360 m / min, 3380 m / min or 3400 m / min;

[0058] The temperature of the second roller is 135°C-150°C, for example, 135°C, 140°C, 145°C or 150°C;

[0059] The winding speed is 3230 m / min-3310 m / min, for example, it can be 3230 m / min, 3250 m / min, 3270 m / min, 3290 m / min or 3310 m / min.

[0060] In some embodiments, the replacement cycle of the filter assembly is 35 days to 40 days, for example, 35 days, 36 days, 37 days, 38 days, 39 days or 40 days. When the spinning melt is filtered, its fluidity will have a direct impact on the difficulty of filtering. When the filtration speed remains basically stable, the pressure required for filtration gradually increases, and when it approaches the bearing limit of the filter assembly, the filter assembly needs to be replaced. In the present invention, the amount of titanium dioxide added is relatively low, so the content of shorter polyester in the spinning melt is reduced, so that the spinning melt has better fluidity, which helps to extend the service life of the filter assembly, that is, to extend the replacement cycle. In addition, due to the low amount of titanium dioxide added, the mechanical properties of the fiber are improved, the difficulty of spinning is reduced, and the number of floating single filaments and broken ends is significantly reduced. After the filter assembly is put on the machine for a certain number of days, the number of broken ends in the spinning process is stably maintained at a low level, which helps to increase the replacement cycle of the filter assembly. It can be seen from the test that the replacement cycle of the filter assembly has been increased from 25-27 days when titanium dioxide is used as a matting agent to 35-40 days.

[0061] See the following examples and comparative examples for details.

[0062] Embodiment 1:

[0063] See also Figure 1 The method for preparing the fully matte polyester fiber shown in a preferred embodiment of the present application comprises:

[0064] S1. Weigh an appropriate amount of polyester chips, add polypropylene chips, polypropylene grafted acrylic acid chips with a grafting rate of 3% and titanium dioxide to obtain spinning raw materials, so that the content of polypropylene is 2.0wt% of polyester, the content of polypropylene grafted acrylic acid is 4.5wt% of polypropylene, and the content of titanium dioxide is 1.7wt% of the spinning raw material.

[0065] S2. The spinning raw material is added to the screw, filtered through a filter assembly, and then extruded from a spinneret, and the extruded filaments are fully stretched and spun, with a single filament fineness of 1.0 dtex, to obtain a fully matte polyester fiber.

[0066] The parameters of full-draw spinning are:

[0067] The cooling temperature is 20°C;

[0068] The network pressure is 0.25MPa;

[0069] One roller speed is 2250m / min;

[0070] The temperature of one roller is 85℃;

[0071] The speed of the second roller is 3350m / min;

[0072] The temperature of the second roller is 138°C;

[0073] The winding speed is 3290m / min.

[0074] The properties of the fiber tested were 3.70cN / dtex for breaking strength, 29% for breaking elongation, 17 pcs / m for network, 0.6% for linear density deviation, 3.8% for breaking strength CV, 8.1% for breaking elongation CV, and 7.5% for boiling water shrinkage. In the wavelength range of 400nm to 700nm, the fiber transmittance was 93.4, the reflectivity was 83.2, and the same filter assembly worked continuously for 38 days and the fiber quality remained stable.

[0075] The beneficial effects of the present invention are that the mechanical strength of the full-dull polyester fiber can be effectively improved, and the service life of the filter component can be increased, which is helpful to improve the fiber quality and reduce the preparation cost.

[0076] Embodiment 2:

[0077] The difference between this embodiment and the first embodiment is that the single fiber fineness in this embodiment is 2.0 dtex, the breaking strength of the obtained fiber is 3.65 cN / dtex, the breaking elongation is 30%, the network degree is 17 / m, the linear density deviation rate is 0.8%, the breaking strength CV value is 4.0%, the breaking elongation CV value is 8.8%, and the boiling water shrinkage is 8.2%. When the wavelength range is 400nm to 700nm, the fiber transmittance is 93.8, the reflectivity is 83.7, and the same filter assembly works continuously for 38 days and still maintains stable fiber quality.

[0078] Comparative Example 1:

[0079] The difference between this comparative example and Example 2 is that polypropylene slices and polypropylene grafted acrylic acid slices are not added in this comparative example, and the mass of titanium dioxide is 2.5% of the total mass of the raw materials. The obtained fiber has a breaking strength of 3.00 cN / dtex, a breaking elongation of 31%, a network degree of 16 pieces / m, a linear density deviation rate of 2.1%, a breaking strength CV value of 5.3%, a breaking elongation CV value of 12.1%, and a boiling water shrinkage of 10.5%. When the wavelength range is 400nm to 700nm, the fiber transmittance is 94.7, the reflectivity is 84.2, and after the same filter assembly has been working continuously for 28 days, floating single filaments and broken ends occur frequently, and the proportion of waste silk is extremely high.

[0080] Comparative Example 2:

[0081] The difference between this comparative example and Example 2 is that no polypropylene grafted acrylic acid chips are added in this comparative example. The breaking strength of the obtained fiber is 3.30 cN / dtex, the breaking elongation is 27%, the network degree is 17 pieces / m, the linear density deviation rate is 1.2%, the breaking strength CV value is 4.6%, the breaking elongation CV value is 9.1%, and the boiling water shrinkage is 7.7%. When the wavelength range is 400nm to 700nm, the fiber transmittance is 93.6, the reflectivity is 83.9, and the same filter assembly works continuously for 33 days and still maintains stable fiber quality.

[0082] Comparative Example 3:

[0083] The difference between this comparative example and Example 2 is that titanium dioxide is not added in this comparative example, and the content of polypropylene is 5.0wt% of polyester. It can be observed with naked eyes that the surface of the obtained fiber has gloss, the breaking strength of the fiber is 3.00cN / dtex, the breaking elongation is 35%, the network degree is 16 / m, the linear density deviation rate is 2.8%, the breaking strength CV value is 8.3%, the breaking elongation CV value is 12.1%, and the boiling water shrinkage is 7.0%. When the wavelength range is 400nm to 700nm, the fiber transmittance is 84.4 and the transmittance is 73.2.

[0084] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0085] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A fully matte polyester fiber, characterized in that: The invention comprises polyester, a doped polymer and titanium dioxide. The polyester and the doped polymer have different refractive indexes, the doped polymer has fiber-forming property, and an interface exists between the doped polymer and the polyester when they are in contact in a molten state. The doped polymer is polypropylene, and the content of the polypropylene is 1.5wt%-2.0wt% of the polyester.

2. The full matte polyester fiber according to claim 1, characterized in that: The invention also comprises a compatibilizer, and the compatibilizer is used for improving the compatibility between the polyester and the doped polymer.

3. The full matte polyester fiber according to claim 2, characterized in that: The compatibilizer is polypropylene grafted with acrylic acid.

4. The full matte polyester fiber according to claim 3, characterized in that: The content of titanium dioxide is 1.7wt%-1.9wt% of the full-dull polyester fiber, the grafting rate of polypropylene grafted with acrylic acid is 2.5%-3.0%, and the content of polypropylene grafted with acrylic acid is 4.0wt%-5.0wt% of the polypropylene.

5. The full matte polyester fiber according to claim 3, characterized in that: The intrinsic viscosity of the polyester melt is 0.65 dL / g-0.70 dL / g, and the melt index of the polypropylene is 16 g / 10 min-20 g / 10 min.

6. The full matte polyester fiber according to any one of claims 1 to 5, characterized in that: The fiber has a single filament fineness of 1.0 dtex-3.0 dtex, a breaking strength of ≥3.30 cN / dtex, an elongation at break of 28%-32%, a network density of 11 / m-19 / m, a linear density deviation rate of ≤1.0%, a breaking strength CV value of ≤5.0%, a breaking elongation CV value of ≤10.0%, and a boiling water shrinkage of 7.0%-8.0%.

7. The full-dull polyester fiber according to any one of claims 1 to 5, characterized in that: The fiber has a transmittance of 93.3-94.4 and a reflectivity of 83.0-84.0 in a wavelength range of 400 nm to 700 nm.

8. A method for preparing the fully matte polyester fiber according to any one of claims 1 to 7, characterized in that: include: Weighing appropriate amounts of the doped polymer, the titanium dioxide and the polyester to obtain a spinning raw material; The spinning raw materials are added into a screw for melting and filtered through a filter assembly, and then filaments are extruded and fully stretched and spun to obtain the fully matte polyester fiber.

9. A method for preparing the fully matte polyester fiber as claimed in claim 8, characterized in that: The parameters of the full-stretch spinning are: Cooling temperature is 20℃-25℃; The network pressure is 0.20MPa-0.30MPa; The speed of one roller is 2200m / min-2300m / min; The temperature of one roller is 80℃-90℃; The speed of the second roller is 3300m / min-3400m / min; The temperature of the second roller is 135℃-150℃; The winding speed is 3230m / min-3310m / min.

10. A method for preparing the fully matte polyester fiber as claimed in claim 8, characterized in that: The replacement period of the filter assembly is 35-40 days.

Images