A kind of water-repellent polyester fiber and preparation method thereof

Abstract

The invention relates to a water-repellent polyester fiber and a preparation method thereof. First, a terminal hydroxyl hyperbranched polyester and an asymmetric alcohol hydroxyl mono-terminated polydimethylsiloxane are subjected to a dehydration reaction to obtain a terminal siloxane hyperbranched polyester, and then polyethylene terephthalate I, a terminal siloxane hyperbranched polyester and a dimethylvinylsiloxy cage-shaped polysilsesquioxane are melt-blended to prepare a water-repellent polyester functional masterbatch, and then polyethylene terephthalate II and the water-repellent polyester functional masterbatch are blended and melt-spun, and finally the surface of the fiber obtained by melt spinning is coated with tri-tert-butoxyvinylsilane, and then a grafting reaction is induced by ultraviolet radiation to obtain the water-repellent polyester fiber; the number average molecular weights of polyethylene terephthalate I and polyethylene terephthalate II are both within the range of 20000-30000 g / mol; and the contact angle of the water-repellent polyester fiber is greater than 145°. The method of the invention is simple, and the obtained product has good mechanical properties and water repellency.

Description

Technical Field

[0001] The invention belongs to the technical field of water-repellent polyester fibers and relates to a water-repellent polyester fiber and a preparation method thereof. Background Art

[0002] In today's rapidly developing industrial and consumer markets, the functionality and durability of textiles have become important criteria for measuring product quality. In particular, in the fields of outdoor equipment, sportswear and industrial applications, the demand for polyester fibers with water-repellent properties is growing. The development of water-repellent polyester fibers can not only improve the performance of products and extend their service life, but also reduce the need for washing and maintenance to a certain extent, thereby reducing the environmental burden.

[0003] In order to improve the hydrophobic properties of polyester fibers or fabrics, patent CN109440476B uses materials such as polydimethylsiloxane, polyurethane and polyacrylate to apply water-repellent finishing on the surface of the fabric. Although the hydrophobic properties of the fabric can be improved, the coating finishing will affect the feel and breathability of the fabric, and the durability of the water-repellent also has certain challenges.

[0004] Patent CN109183412A uses caustic soda to pre-treat polyester, so that the ester bonds on the fiber surface are hydrolyzed to produce hydroxyl groups; the hydroxyl groups on the polyester react with vinyl ethylene oxide to introduce vinyl groups on the polyester fiber, and with the help of ultraviolet radiation and photoinitiators, the vinyl groups on the polyester are promoted to undergo graft copolymerization with fluorinated acrylate monomers, thereby achieving a longer-lasting water-repellent finish on the polyester fabric. However, since polyester needs to be hydrolyzed and grafted, the mechanical properties of the product will be affected, which will affect the service life of the product.

[0005] Patent CN112281239A obtains a water-repellent dibasic acid ester by hydrolyzing ethylene glycol and pentaerythritol ester, and then transesterifies the ester with a prepolymer to obtain a water-repellent polyester polymer, and then melt-spins the water-repellent polyester fiber with a contact angle of 135-145°. However, the chemical structure design process of this patent is relatively complicated, and the copolymer structure destroys the regularity of the polyester structure to a certain extent, affecting its spinnability and fiber strength.

[0006] Patent CN111041585A discloses a method for preparing water-repellent polyester masterbatch. However, the patent adopts the conventional functional masterbatch addition and melt spinning method. The functional material is often evenly distributed inside the fiber and cannot achieve a good water-repellent effect. In order to improve the water-repellent effect of the product, it is often necessary to add a large amount of water-repellent masterbatch, which leads to a decrease in the strength of the fiber.

[0007] The literature (Preparation and Performance Study of PDMS-modified PA6 and PET Fibers [D]. Donghua University, 2020.06) prepared PET / PDMS fibers by melt blending, but its contact angle was only 123°, which needs to be improved.

[0008] Patent CN113862828A prepared a high-flow water-repellent masterbatch and a conventional polyester for co-spinning. The viscosity difference between the masterbatch and the conventional polyester was used to prepare a water-repellent polyester fiber with a skin-core structure. The water-repellent material is conducive to enrichment in the fiber surface layer, which greatly improves the utilization efficiency of the water-repellent material. However, in order to make the water-repellent functional material present a heterogeneous distribution in the radial direction of the fiber, the high-flow polyester used in the masterbatch and the conventional polyester need to have a large viscosity difference. Low molecular weight polyester is often used as the carrier resin of the masterbatch, which results in low melt strength during the spinning process and often affects the stability of the filament. In addition, in addition to being related to the composition of the blend, this heterogeneous flow extrusion during the spinning process is also strongly dependent on the forming process conditions, including the spinneret hole structure, cooling forming conditions, etc.

[0009] Therefore, it is of great significance to study a water-repellent polyester fiber with excellent spinnability, good water repellency and excellent mechanical properties and a preparation method thereof to solve the problems existing in the prior art. Summary of the invention

[0010] The purpose of the present invention is to solve the problems existing in the prior art and provide a water-repellent polyester fiber and a preparation method thereof.

[0011] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0012] A method for preparing water-repellent polyester fiber comprises the following steps: firstly, a terminal hydroxyl hyperbranched polyester and an asymmetric alcohol hydroxyl mono-terminated polydimethylsiloxane (the reason why the asymmetric alcohol hydroxyl mono-terminated polydimethylsiloxane and the terminal hydroxyl hyperbranched polyester are used to react is mainly because the asymmetric alcohol hydroxyl mono-terminated polydimethylsiloxane has only one hydroxyl group, which can react with the hydroxyl group of the terminal hydroxyl hyperbranched polyester. If the number of hydroxyl groups is large, it is easy to interact with water molecules, which is not conducive to the subsequent water-collecting effect of the fiber) are subjected to a dehydration reaction to obtain a terminal siloxane hyperbranched polyester; then, polyethylene terephthalate I, the terminal siloxane hyperbranched polyester and dimethylvinylsiloxy cage-like polysilsesquioxane are melt-blended to prepare a water-repellent polyester functional masterbatch; then, polyethylene terephthalate II and the water-repellent polyester functional masterbatch are blended and melt-spun; finally, the surface of the fiber obtained by melt spinning is coated with tri-tert-butoxyvinylsilane, and then ultraviolet radiation is induced to induce a grafting reaction to obtain the water-repellent polyester fiber;

[0013] The number average molecular weights of polyethylene terephthalate I and polyethylene terephthalate II are both in the range of 20000~30000 g / mol.

[0014] As the preferred technical solution:

[0015] In the method for preparing the water-repellent polyester fiber as described above, the dehydration reaction is carried out under a pressure of -0.01 to 0.05 MPa, the reaction temperature is 110 to 125° C., and the reaction time is 40 to 60 minutes.

[0016] In the method for preparing a water-repellent polyester fiber as described above, the molar ratio of the terminal hydroxyl hyperbranched polyester to the asymmetric alcohol hydroxyl mono-terminated polydimethylsiloxane is 1:8-8.03.

[0017] In the preparation method of a water-repellent polyester fiber as described above, the mass fraction of polyethylene terephthalate I in the water-repellent polyester functional masterbatch is 60-70%, the mass fraction of the terminal siloxane hyperbranched polyester is 15-25%, and the mass fraction of dimethylvinylsiloxy caged polysilsesquioxane is 5-25%.

[0018] In the method for preparing the water-repellent polyester fiber as described above, the melt extrusion temperature when preparing the water-repellent polyester functional masterbatch is 250-255°C.

[0019] In the method for preparing water-repellent polyester fiber as described above, the total amount of polyethylene terephthalate II and water-repellent polyester functional masterbatch is taken as a basis, and the mass proportion of the water-repellent polyester functional masterbatch is 5-10%.

[0020] The preparation method of a water-repellent polyester fiber as described above, the process parameters of melt spinning include: a spinning temperature of 275~285°C, an aspect ratio of the spinneret hole of 1.3~1.5:1, the temperature of the slow cooling zone is the same as the spinning temperature, the height of the slow cooling zone is 2~3cm, the cooling blowing speed is 0.4~0.6m / s, the cooling blowing temperature is 22~25°C, the spinning speed (i.e., one roller speed) is 600~2500m / min, and the post-drafting multiple is 2.5~5.5 times.

[0021] In the method for preparing water-repellent polyester fiber as described above, the coating amount of tri-tert-butoxyvinylsilane is 0.1-0.3% of the fiber mass.

[0022] In the method for preparing a water-repellent polyester fiber as described above, the ultraviolet irradiation intensity is 30-50 mW / cm 2 , irradiation time is 20~100s.

[0023] The present invention also provides a water-repellent polyester fiber prepared by the method described in any one of the above items, wherein the contact angle of the water-repellent polyester fiber is greater than 145°; after being washed 50 times, the contact angle of the water-repellent polyester fiber is greater than 143°.

[0024] As the preferred technical solution:

[0025] The water-repellent polyester fiber as described above has a single fiber fineness of 1.5-7 dtex, a breaking strength of >3.8 cN / dtex, and an elongation at break of 20-30%.

[0026] Invention mechanism:

[0027] The present invention firstly utilizes the hydroxyl group in the terminal hydroxyl hyperbranched polyester to react with the hydroxyl group in the asymmetric alcohol hydroxyl mono-terminated polydimethylsiloxane to generate the terminal siloxane hyperbranched polyester. The terminal siloxane hyperbranched polyester has a large molecular weight and exhibits a stronger elastic effect during the extrusion process. Moreover, its branched structure is more sensitive to shear stress, and the outlet puffing effect is more significant. After being extruded from the spinneret hole, it is easier to diffuse and enrich toward the surface of the filament. At the same time, in order to improve the dispersibility of functional materials in the prior art, the carrier resin of the masterbatch is usually granulated with a low molecular weight resin (low system viscosity), which results in too wide molecular weight dispersion when added during spinning, affecting the fiber performance. However, the present invention adds the terminal siloxane hyperbranched polyester, because the surface energy of the polysiloxane structure it has is low, it can play the role of internal lubrication, thereby reducing the system viscosity, so a high molecular weight carrier resin (i.e., polyethylene terephthalate I of the present invention) can be used. In the process of masterbatch preparation, since the low molecular weight and high fluidity carrier resin is abandoned, it can be avoided that the molecular weight distribution of the fiber-forming polymer is too wide due to the addition of masterbatch during the spinning process, which affects the strength of the fiber, and the spinnability of the masterbatch added spinning can be guaranteed.

[0028] The terminal siloxane hyperbranched polyester and dimethylvinylsiloxy caged polysilsesquioxane are water-repellent functional components. The terminal siloxane hyperbranched polyester and dimethylvinylsiloxy caged polysilsesquioxane have similar polarity and are similarly compatible. When the terminal siloxane hyperbranched polyester diffuses to the surface of the filament, it is also easy to drive the dimethylvinylsiloxy caged polysilsesquioxane to enrich on the fiber surface, thereby reducing the specific surface energy of the fiber and improving the water-repellent effect when a small amount of functional materials (i.e., terminal siloxane hyperbranched polyester and dimethylvinylsiloxy caged polysilsesquioxane) is added. In addition, after the filament is solidified, the dimethylvinylsiloxy caged polysilsesquioxane easily forms a micro-convex structure on the fiber surface, increasing the roughness of the fiber surface, which is conducive to further improving the water-repellent effect.

[0029] Finally, since the dimethylvinylsiloxy cage-like polysilsesquioxane enriched on the fiber surface contains unsaturated double bonds, low ultraviolet irradiation can induce it to form a grafted structure with tri-tert-butoxyvinyl silane without damaging the fiber matrix. Tri-tert-butoxyvinyl silane has a low surface energy, thereby enhancing the water-repellent function.

[0030] Beneficial effects:

[0031] (1) A method for preparing a water-repellent polyester fiber of the present invention utilizes the hydroxyl groups in a terminal hydroxyl hyperbranched polyester to react with the hydroxyl groups in asymmetric alcohol hydroxyl mono-terminated polydimethylsiloxane to generate a terminal siloxane-based hyperbranched polyester. With a relatively small amount of functional material added, the specific surface energy of the fiber can be reduced and the water-repellent effect can be improved.

[0032] (2) The preparation method of the water-repellent polyester fiber of the present invention abandons the low molecular weight and high fluidity carrier resin, which can avoid the molecular weight distribution of the fiber-forming polymer being too wide due to the addition of the masterbatch during the spinning process, thereby affecting the strength of the fiber, and can ensure the spinnability of the spinning after the addition of the masterbatch.

[0033] (3) The water-repellent polyester fiber of the present invention has excellent spinnability, good water-repellent properties and excellent mechanical properties. DETAILED DESCRIPTION

[0034] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0035] The test methods involved in the performance indicators in the embodiments and comparative examples of the present invention are as follows:

[0036] Contact angle: The fiber contact angle is tested using the LSA 100M2 fiber contact angle meter equipped with a microscope lens and a picoliter injection unit. 100 picoliters of droplet (water droplet) is dropped on the fiber, the droplet morphology is observed under a microscope, and the contact angle is tested. Before the sample test, the sample is dried to a moisture content of less than 100 ppm.

[0037] Washing: refer to the washing method in standard GB / T 3921-2008.

[0038] Breaking strength and breaking elongation: tested in accordance with standard GB / T 16604-2017.

[0039] The sources of some substances of the present invention are as follows:

[0040] Hydroxyl-terminated hyperbranched polyester: Hyper H201 from Wuhan Hyperbranched Resin Technology Co., Ltd.

[0041] Asymmetric alcohol hydroxyl mono-terminated polydimethylsiloxane: CAS number: 207308-30-3.

[0042] Tri-tert-butoxyvinylsilane: CAS number: 5356-88-7.

[0043] Dimethylvinylsiloxy cage polysilsesquioxane: Manufacturer: Guangzhou Yixin Technology Co., Ltd., Brand: Ecotion® POSS1016.

[0044] Example 1

[0045] A method for preparing a water-repellent polyester fiber, the specific steps are as follows:

[0046] (1) The terminal hydroxyl hyperbranched polyester and the asymmetric alcohol hydroxyl mono-terminated polydimethylsiloxane are subjected to a dehydration reaction at a pressure of -0.01 MPa and a temperature of 110° C. for 60 minutes to obtain a terminal siloxane hyperbranched polyester;

[0047] The molar ratio of the hydroxyl-terminated hyperbranched polyester to the asymmetric alcohol hydroxyl-terminated polydimethylsiloxane is 1:8;

[0048] (2) preparing a water-repellent polyester functional masterbatch by melt blending polyethylene terephthalate I (number average molecular weight of 20,000 g / mol), terminal siloxane hyperbranched polyester and dimethylvinylsiloxy caged polysilsesquioxane;

[0049] The mass fraction of polyethylene terephthalate I in the water-repellent polyester functional masterbatch is 60%, the mass fraction of terminal siloxane hyperbranched polyester is 15%, and the mass fraction of dimethylvinylsiloxy cage polysilsesquioxane is 25%; the melt extrusion temperature is 250°C;

[0050] (3) blending polyethylene terephthalate II (number average molecular weight of 20,000 g / mol) and water-repellent polyester functional masterbatch and then melt spinning;

[0051] Among them, based on the total amount of polyethylene terephthalate II and water-repellent polyester functional masterbatch, the mass proportion of water-repellent polyester functional masterbatch is 5%;

[0052] The process parameters of melt spinning include: spinning temperature of 275°C, aspect ratio of spinneret hole of 1.3:1, temperature of slow cooling zone is the same as spinning temperature, height of slow cooling zone is 2 cm, cooling air speed is 0.4 m / s, cooling air temperature is 22°C, spinning speed is 600 m / min, and post-drafting multiple is 5.5 times;

[0053] (4) coating the surface of the fiber obtained by melt spinning with tri-tert-butoxyvinyl silane, and then inducing a grafting reaction by ultraviolet irradiation to obtain a water-repellent polyester fiber;

[0054] The coating amount of tri-tert-butoxyvinylsilane is 0.30% of the fiber mass; the UV irradiation intensity is 30mW / cm 2 , irradiation time is 100s.

[0055] The final water-repellent polyester fiber has a single filament fineness of 7 dtex, a breaking strength of 3.81 cN / dtex, a breaking elongation of 30%, a contact angle of 149°, and a contact angle of 147° after washing 50 times.

[0056] Comparative Example 1

[0057] A method for preparing polyester fiber is basically the same as that of Example 1, except that the terminal siloxane hyperbranched polyester in step (2) is replaced by a terminal hydroxyl hyperbranched polyester.

[0058] The contact angle of the polyester fiber finally obtained was 102°.

[0059] By comparing Comparative Example 1 with Example 1, it can be found that the contact angle of the polyester fiber prepared in Comparative Example 1 is significantly reduced. This is because the terminal hydroxyl hyperbranched polyester contains a large number of hydroxyl groups and is very easy to absorb water, resulting in a decrease in the contact angle of the fiber.

[0060] Comparative Example 2

[0061] A method for preparing polyester fiber is basically the same as that of Example 1, except that the terminal siloxane hyperbranched polyester in step (2) is replaced by polydimethylsiloxane.

[0062] The contact angle of the polyester fiber finally obtained was 130°.

[0063] By comparing Comparative Example 2 with Example 1, it can be found that the contact angle in Comparative Example 2 is significantly lower than that in Example 1. This is because polydimethylsiloxane, as a linear macromolecule, has a weak outlet expansion effect during the extrusion process and a low degree of migration toward the fiber surface, which cannot drive the dimethylvinylsiloxy cage-like polysilsesquioxane to enrich toward the fiber surface, resulting in a weakened water-repellent effect.

[0064] Comparative Example 3

[0065] A method for preparing polyester fiber is basically the same as that of Example 1, except that the operation of step (4) is omitted.

[0066] The contact angle of the polyester fiber finally obtained was 110°.

[0067] Comparing Comparative Example 3 with Example 1, it can be found that the contact angle of Comparative Example 3 is significantly lower than that of Example 1. This is because the fiber surface lacks a grafting reaction with tri-tert-butoxyvinylsilane and the surface energy of the fiber is high, resulting in a lower contact angle.

[0068] Comparative Example 4

[0069] A method for preparing polyester fiber is basically the same as that of Example 1, except that after coating tri-tert-butoxyvinylsilane in step (4), the ultraviolet irradiation operation is omitted and the fiber is directly dried and cured at 60°C.

[0070] The contact angle of the polyester fiber finally obtained was 140°, and the contact angle was 108° after washing 50 times.

[0071] By comparing Comparative Example 4 with Example 1, it can be found that the contact angle of the fiber in Comparative Example 4 decreases significantly after washing. This is because due to the lack of ultraviolet radiation, tri-tert-butoxyvinyl silane does not form a covalent bond with the fiber matrix, the binding force is weak, the coating layer falls off during the washing process, and the contact angle decreases.

[0072] Example 2

[0073] A method for preparing a water-repellent polyester fiber, the specific steps are as follows:

[0074] (1) The hydroxyl-terminated hyperbranched polyester and the asymmetric alcohol hydroxyl-terminated polydimethylsiloxane were subjected to a dehydration reaction at a pressure of 0.01 MPa and a temperature of 112° C. for 55 minutes to obtain a siloxane-terminated hyperbranched polyester;

[0075] The molar ratio of the hydroxyl-terminated hyperbranched polyester to the asymmetric alcohol hydroxyl-terminated polydimethylsiloxane is 1:8.01;

[0076] (2) preparing a water-repellent polyester functional masterbatch by melt blending polyethylene terephthalate I (number average molecular weight of 22000 g / mol), terminal siloxane hyperbranched polyester and dimethylvinylsiloxy cage polysilsesquioxane;

[0077] Among them, the mass fraction of polyethylene terephthalate I in the water-repellent polyester functional masterbatch is 62%, the mass fraction of terminal siloxane hyperbranched polyester is 17%, and the mass fraction of dimethylvinylsiloxy cage polysilsesquioxane is 21%; the melt extrusion temperature is 251°C;

[0078] (3) blending polyethylene terephthalate II (number average molecular weight of 22000 g / mol) with water-repellent polyester functional masterbatch and then melt spinning;

[0079] Among them, based on the total amount of polyethylene terephthalate II and water-repellent polyester functional masterbatch, the mass proportion of water-repellent polyester functional masterbatch is 6%;

[0080] The process parameters of melt spinning include: spinning temperature of 278°C, aspect ratio of spinneret hole of 1.35:1, temperature of slow cooling zone is the same as spinning temperature, height of slow cooling zone is 2.2 cm, cooling blowing speed is 0.45 m / s, cooling blowing temperature is 22.5°C, spinning speed is 1000 m / min, and post-drafting multiple is 5 times;

[0081] (4) coating the surface of the fiber obtained by melt spinning with tri-tert-butoxyvinyl silane, and then inducing a grafting reaction by ultraviolet irradiation to obtain a water-repellent polyester fiber;

[0082] The coating amount of tri-tert-butoxyvinylsilane is 0.25% of the fiber mass; the UV irradiation intensity is 35mW / cm 2 , the irradiation time is 80s.

[0083] The final water-repellent polyester fiber has a single filament fineness of 6 dtex, a breaking strength of 4 cN / dtex, an elongation at break of 28%, a contact angle of 148°, and a contact angle of 146.3° after washing 50 times.

[0084] Example 3

[0085] A method for preparing a water-repellent polyester fiber, the specific steps are as follows:

[0086] (1) The terminal hydroxyl hyperbranched polyester and the asymmetric alcohol hydroxyl mono-terminated polydimethylsiloxane are subjected to a dehydration reaction at a pressure of 0.02 MPa and a temperature of 115° C. for 50 minutes to obtain a terminal siloxane hyperbranched polyester;

[0087] The molar ratio of the terminal hydroxyl hyperbranched polyester to the asymmetric alcohol hydroxyl mono-terminated polydimethylsiloxane is 1:8.015;

[0088] (2) preparing a water-repellent polyester functional masterbatch by melt blending polyethylene terephthalate I (number average molecular weight of 25000 g / mol), terminal siloxane hyperbranched polyester and dimethylvinylsiloxy caged polysilsesquioxane;

[0089] Among them, the mass fraction of polyethylene terephthalate I in the water-repellent polyester functional masterbatch is 64%, the mass fraction of terminal siloxane hyperbranched polyester is 19%, and the mass fraction of dimethylvinylsiloxy cage polysilsesquioxane is 17%; the melt extrusion temperature is 252°C;

[0090] (3) blending polyethylene terephthalate II (number average molecular weight of 25000 g / mol) with water-repellent polyester functional masterbatch and then melt spinning;

[0091] Among them, based on the total amount of polyethylene terephthalate II and water-repellent polyester functional masterbatch, the mass proportion of water-repellent polyester functional masterbatch is 7%;

[0092] The process parameters of melt spinning include: spinning temperature of 280°C, aspect ratio of spinneret hole of 1.4:1, temperature of slow cooling zone is the same as spinning temperature, height of slow cooling zone is 2.4 cm, cooling air speed is 0.5 m / s, cooling air temperature is 23°C, spinning speed is 2500 m / min, and post-drafting multiple is 2.5 times;

[0093] (4) coating the surface of the fiber obtained by melt spinning with tri-tert-butoxyvinyl silane, and then inducing a grafting reaction by ultraviolet irradiation to obtain a water-repellent polyester fiber;

[0094] The coating amount of tri-tert-butoxyvinylsilane is 0.20% of the fiber mass; the UV irradiation intensity is 40mW / cm 2 , the irradiation time is 60s.

[0095] The final water-repellent polyester fiber had a single filament fineness of 5 dtex, a breaking strength of 4.2 cN / dtex, an elongation at break of 26%, a contact angle of 147.5°, and a contact angle of 145.8° after washing 50 times.

[0096] Example 4

[0097] A method for preparing a water-repellent polyester fiber, the specific steps are as follows:

[0098] (1) The terminal hydroxyl hyperbranched polyester and the asymmetric alcohol hydroxyl mono-terminated polydimethylsiloxane are subjected to a dehydration reaction at a pressure of 0.03 MPa and a temperature of 118° C. for 48 minutes to obtain a terminal siloxane hyperbranched polyester;

[0099] The molar ratio of the hydroxyl-terminated hyperbranched polyester to the asymmetric alcohol hydroxyl-terminated polydimethylsiloxane is 1:8.02;

[0100] (2) preparing a water-repellent polyester functional masterbatch by melt blending polyethylene terephthalate I (number average molecular weight of 28000 g / mol), terminal siloxane hyperbranched polyester and dimethylvinylsiloxy caged polysilsesquioxane;

[0101] Among them, the mass fraction of polyethylene terephthalate I in the water-repellent polyester functional masterbatch is 66%, the mass fraction of terminal siloxane hyperbranched polyester is 21%, and the mass fraction of dimethylvinylsiloxy cage polysilsesquioxane is 13%; the melt extrusion temperature is 253°C;

[0102] (3) blending polyethylene terephthalate II (number average molecular weight of 28000 g / mol) with water-repellent polyester functional masterbatch and then melt spinning;

[0103] Among them, based on the total amount of polyethylene terephthalate II and water-repellent polyester functional masterbatch, the mass proportion of water-repellent polyester functional masterbatch is 8%;

[0104] The process parameters of melt spinning include: spinning temperature of 282°C, aspect ratio of spinneret hole of 1.43:1, temperature of slow cooling zone is the same as spinning temperature, height of slow cooling zone is 2.5 cm, cooling air speed is 0.5 m / s, cooling air temperature is 23.5°C, spinning speed is 800 m / min, and post-drafting multiple is 5.3 times;

[0105] (4) coating the surface of the fiber obtained by melt spinning with tri-tert-butoxyvinyl silane, and then inducing a grafting reaction by ultraviolet irradiation to obtain a water-repellent polyester fiber;

[0106] The coating amount of tri-tert-butoxyvinylsilane is 0.18% of the fiber mass; the UV irradiation intensity is 45mW / cm 2 , the irradiation time is 50s.

[0107] The final water-repellent polyester fiber had a single filament fineness of 4 dtex, a breaking strength of 4.29 cN / dtex, an elongation at break of 23.5%, a contact angle of 147°, and a contact angle of 145° after washing 50 times.

[0108] Example 5

[0109] A method for preparing a water-repellent polyester fiber, the specific steps are as follows:

[0110] (1) The hydroxyl-terminated hyperbranched polyester and the asymmetric alcohol hydroxyl-terminated polydimethylsiloxane are subjected to a dehydration reaction at a pressure of 0.04 MPa and a temperature of 120° C. for 45 minutes to obtain a siloxane-terminated hyperbranched polyester;

[0111] The molar ratio of the hydroxyl-terminated hyperbranched polyester to the asymmetric alcohol hydroxyl-terminated polydimethylsiloxane is 1:8.025;

[0112] (2) preparing a water-repellent polyester functional masterbatch by melt blending polyethylene terephthalate I (number average molecular weight of 29000 g / mol), terminal siloxane hyperbranched polyester and dimethylvinylsiloxy caged polysilsesquioxane;

[0113] Among them, the mass fraction of polyethylene terephthalate I in the water-repellent polyester functional masterbatch is 68%, the mass fraction of terminal siloxane hyperbranched polyester is 23%, and the mass fraction of dimethylvinylsiloxy cage polysilsesquioxane is 9%; the melt extrusion temperature is 254°C;

[0114] (3) blending polyethylene terephthalate II (number average molecular weight of 29000 g / mol) with water-repellent polyester functional masterbatch and then melt spinning;

[0115] Among them, based on the total amount of polyethylene terephthalate II and water-repellent polyester functional masterbatch, the mass proportion of water-repellent polyester functional masterbatch is 9%;

[0116] The process parameters of melt spinning include: spinning temperature of 285°C, aspect ratio of spinneret hole of 1.48:1, temperature of slow cooling zone is the same as spinning temperature, height of slow cooling zone is 2.8 cm, cooling blowing speed is 0.55 m / s, cooling blowing temperature is 24°C, spinning speed is 1500 m / min, and post-drafting multiple is 4.5 times;

[0117] (4) coating the surface of the fiber obtained by melt spinning with tri-tert-butoxyvinyl silane, and then inducing a grafting reaction by ultraviolet irradiation to obtain a water-repellent polyester fiber;

[0118] The coating amount of tri-tert-butoxyvinylsilane is 0.15% of the fiber mass; the UV irradiation intensity is 48mW / cm 2 , the irradiation time is 30s.

[0119] The final water-repellent polyester fiber had a single filament fineness of 2 dtex, a breaking strength of 4.3 cN / dtex, an elongation at break of 21%, a contact angle of 146.8°, and a contact angle of 144.6° after washing 50 times.

[0120] Example 6

[0121] A method for preparing a water-repellent polyester fiber, the specific steps are as follows:

[0122] (1) The hydroxyl-terminated hyperbranched polyester and the asymmetric alcohol hydroxyl-terminated polydimethylsiloxane are subjected to a dehydration reaction at a pressure of 0.05 MPa and a temperature of 125° C. for 40 minutes to obtain a siloxane-terminated hyperbranched polyester;

[0123] The molar ratio of the hydroxyl-terminated hyperbranched polyester to the asymmetric alcohol hydroxyl-terminated polydimethylsiloxane is 1:8.03;

[0124] (2) preparing a water-repellent polyester functional masterbatch by melt blending polyethylene terephthalate I (number average molecular weight of 30,000 g / mol), terminal siloxane hyperbranched polyester and dimethylvinylsiloxy caged polysilsesquioxane;

[0125] Among them, the mass fraction of polyethylene terephthalate I in the water-repellent polyester functional masterbatch is 70%, the mass fraction of terminal siloxane hyperbranched polyester is 25%, and the mass fraction of dimethylvinylsiloxy cage polysilsesquioxane is 5%; the melt extrusion temperature is 255°C;

[0126] (3) blending polyethylene terephthalate II (number average molecular weight of 30,000 g / mol) and water-repellent polyester functional masterbatch and then melt spinning;

[0127] Among them, based on the total amount of polyethylene terephthalate II and water-repellent polyester functional masterbatch, the mass proportion of water-repellent polyester functional masterbatch is 10%;

[0128] The process parameters of melt spinning include: spinning temperature of 285°C, aspect ratio of spinneret hole of 1.5:1, temperature of slow cooling zone is the same as spinning temperature, height of slow cooling zone is 3 cm, cooling air velocity is 0.6 m / s, cooling air temperature is 25°C, spinning speed is 2000 m / min, and post-drafting multiple is 3 times;

[0129] (4) coating the surface of the fiber obtained by melt spinning with tri-tert-butoxyvinyl silane, and then inducing a grafting reaction by ultraviolet irradiation to obtain a water-repellent polyester fiber;

[0130] The coating amount of tri-tert-butoxyvinylsilane is 0.10% of the fiber mass; the UV irradiation intensity is 50mW / cm 2 , the irradiation time is 20s.

[0131] The final water-repellent polyester fiber has a single fiber fineness of 1.5 dtex, a breaking strength of 4.6 cN / dtex, an elongation at break of 20%, a contact angle of 145.1°, and a contact angle of 143.1° after washing 50 times.

Claims

1. A method for preparing a water-repellent polyester fiber, characterized in that: Firstly, a terminal hydroxyl hyperbranched polyester and an asymmetric alcohol hydroxyl mono-terminated polydimethylsiloxane are subjected to a dehydration reaction to obtain a terminal siloxane hyperbranched polyester, and then polyethylene terephthalate I, a terminal siloxane hyperbranched polyester and dimethylvinylsiloxy cage-like polysilsesquioxane are melt-blended to prepare a water-repellent polyester functional masterbatch, and then polyethylene terephthalate II and the water-repellent polyester functional masterbatch are blended and melt-spun, and finally, the surface of the fiber obtained by melt spinning is coated with tri-tert-butoxyvinyl silane, and then a grafting reaction is induced by ultraviolet irradiation to obtain a water-repellent polyester fiber; The number average molecular weights of polyethylene terephthalate I and polyethylene terephthalate II are both in the range of 20000~30000 g / mol.

2. The method for preparing a water-repellent polyester fiber according to claim 1, characterized in that: The dehydration reaction is carried out under a pressure of -0.01 to 0.05 MPa, a reaction temperature of 110 to 125° C., and a reaction time of 40 to 60 minutes.

3. The method for preparing a water-repellent polyester fiber according to claim 2, characterized in that: The molar ratio of the terminal hydroxyl hyperbranched polyester to the asymmetric alcohol hydroxyl mono-terminated polydimethylsiloxane is 1:8-8.

03.

4. The method for preparing a water-repellent polyester fiber according to claim 1, characterized in that: The mass fraction of polyethylene terephthalate I in the water-repellent polyester functional masterbatch is 60-70%, the mass fraction of terminal siloxane hyperbranched polyester is 15-25%, and the mass fraction of dimethylvinylsiloxy cage polysilsesquioxane is 5-25%.

5. The method for preparing a water-repellent polyester fiber according to claim 4, characterized in that: The melt extrusion temperature for preparing the water-repellent polyester functional masterbatch is 250-255°C.

6. The method for preparing a water-repellent polyester fiber according to claim 1, characterized in that: Based on the total amount of polyethylene terephthalate II and water-repellent polyester functional masterbatch, the mass proportion of water-repellent polyester functional masterbatch is 5~10%.

7. The method for preparing a water-repellent polyester fiber according to claim 1, characterized in that: The process parameters of melt spinning include: spinning temperature of 275~285℃, aspect ratio of spinneret hole of 1.3~1.5:1, temperature of slow cooling zone is the same as spinning temperature, height of slow cooling zone is 2~3cm, cooling blowing speed is 0.4~0.6m / s, cooling blowing temperature is 22~25℃, spinning speed is 600~2500m / min, and post-drawing multiple is 2.5~5.5 times.

8. The method for preparing a water-repellent polyester fiber according to claim 1, characterized in that: The coating amount of tri-tert-butoxyvinyl silane is 0.1~0.3% of the fiber mass.

9. The method for preparing a water-repellent polyester fiber according to claim 1, characterized in that: UV radiation intensity is 30~50 mW / cm 2 , irradiation time is 20~100s.

10. A water-repellent polyester fiber prepared by the method according to any one of claims 1 to 9, characterized in that: The contact angle of the water-repellent polyester fiber is greater than 145°; after washing 50 times, the contact angle of the water-repellent polyester fiber is greater than 143°.

11. The water-repellent polyester fiber according to claim 10, characterized in that: The monofilament fineness of the water-repellent polyester fiber is 1.5~7dtex, the breaking strength is >3.8cN / dtex, and the breaking elongation is 20~30%.