Polyphenylene sulfide composite fiber as well as preparation method and application thereof

Abstract

The invention discloses a polyphenylene sulfide composite fiber as well as a preparation method and application thereof, and belongs to the technical field of composite fibers and air filtering materials. The method comprises the following steps: (1) respectively drying and melting PPS and a core layer material; a flow promoter is added in the melting process of the PPS; (2) spinning and compounding the molten PPS and the core layer material to obtain a skin layer PPS / core layer composite fiber, and then drafting; and (3) chopping the drafted skin layer PPS / core layer composite fiber, putting the chopped fiber into a dipping tank for dipping, and taking out and drying the dipped fiber to obtain the composite fiber. The method has the beneficial effects that the process steps are simple, the PPS fiber can be manufactured through the process, the mechanical property of the core layer fiber is kept, and the temperature resistance and corrosion resistance of the PPS fiber are also kept. Meanwhile, the fiber cost can be effectively reduced. The PPS / core layer composite fiber with improved fiber mechanical properties can meet actual use requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of composite fibers and air filter materials, in particular to a polyphenylene sulfide composite fiber and a preparation method and application thereof. Background Art

[0002] Polyphenylene sulfide (PPS) is a lightweight, high-performance material with significantly higher strength retention at high temperatures than engineering plastics such as polybutylene terephthalate (PBT), polyethersulfone (PES), and polycarbonate (PC). PPS also offers advantages such as flame retardancy, corrosion resistance, radiation resistance, fatigue resistance, high hardness, low shrinkage and linear expansion coefficient, and low water absorption, making it a superior material for high-temperature filtration applications compared to glass fiber and meta-aramid.

[0003] However, PPS fibers have poor flowability during spinning, resulting in a low yield rate. High raw material prices significantly increase costs. Therefore, the present invention provides a polyphenylene sulfide composite fiber and a method for preparing the same.

[0004] Patent publication number KR1020180024670A discloses a sheath-core composite spinning solution-dyed polyphenylene sulfide composite fiber. The sheath is composed of a polyphenylene sulfide resin, and the core is a polyester, polyamide, polyolefin, or a solution-dyed polyphenylene sulfide conjugate fiber. The fiber is cis-core conjugate spun with a black masterbatch added to any vinyl compound, improving spinning processability and providing excellent heat resistance. However, the patent does not disclose the preparation method of the polyphenylene sulfide composite fiber of the present invention. Summary of the Invention

[0005] The technical problem to be solved by the present invention is how to provide a polyphenylene sulfide composite fiber material with good fluidity, high strength and corrosion resistance.

[0006] The present invention solves the above technical problems through the following technical means:

[0007] A first aspect of the present invention provides a method for preparing a polyphenylene sulfide composite fiber, comprising the following steps:

[0008] (1) PPS and a core layer material are dried and melted separately; a flow promoter is added to the PPS during the melting process; the core layer material is at least one of PET, PA6, PA66, and PBT;

[0009] (2) spinning and compounding the melted PPS and core layer material to obtain skin layer PPS / core layer composite fiber, and then performing a drafting process;

[0010] (3) After the stretching, the skin PPS / core composite fiber is chopped and placed in an immersion tank for immersion. After immersion, it is taken out and dried to obtain the obtained fiber; the solution in the immersion tank is PTFE emulsion or modified PFA emulsion.

[0011] Preferably, the drying temperature in step (1) is 120° C. to 150° C., and the drying time is 12 hours or more.

[0012] Preferably, the proportion of the flow promoter added in step (1) is 0.5-2% of the mass of PPS.

[0013] Preferably, the preparation method of the flow promoter comprises the following steps: adding 10 to 20 parts of 3 to 5C aliphatic alcohol, adding 20 to 40 parts of polydodecene, and 1 to 2 parts of dibutylhydroxytoluene into a reactor, reacting for 5 to 8 hours under vacuum conditions, the vacuum degree is 50Pa, the reaction temperature is controlled at 50 to 80°C, and the pressure during the reaction process is 0.2 to 0.5Mpa.

[0014] Preferably, in step (2), the PPS spinning temperature is controlled at 300-325° C., the core layer spinning temperature is controlled at 258-275° C., and the spinning speed is 600-800 m / min.

[0015] Preferably, the composite ratio (mass ratio) of PPS to the core layer in step (2) is (4-6):(6-4).

[0016] Preferably, in step (2), the stretching ratio is 2.5-3.5, the stretching temperature is 80-120° C., the setting temperature is 150-180° C., and the stretching speed is 500-800 m / min.

[0017] Preferably, the mass percentage concentration of the PTFE emulsion or modified PFA emulsion in step (3) is 10-20%;

[0018] The preparation method of the modified PFA emulsion comprises the following steps:

[0019] Add a solvent and a cross-linking agent into a reactor, wherein the solvent is deionized water and the cross-linking agent is 2,5-dimethyl-2,5-di-tert-butyl peroxide hexane. Add 50-80 parts of deionized water, 1-5 parts of 2,5-dimethyl-2,5-di-tert-butyl peroxide hexane, 20-30 parts of PFA resin, and 10-20 parts of fluorine-containing acrylate. The reaction temperature is 50-100° C. and the reaction is carried out under vacuum with a vacuum degree of 50 Pa and a reaction pressure of 2.0-2.5 MPa. The reaction is carried out for 2-3 hours. During the reaction, 5-10 parts of polyvinylidene fluoride are added.

[0020] Preferably, the drying temperature in step (3) is 120-150°C.

[0021] A second aspect of the present invention provides a polyphenylene sulfide composite fiber prepared by the above preparation method.

[0022] A third aspect of the present invention provides the use of the polyphenylene sulfide composite fiber as an air filter material.

[0023] The advantages of the present invention are:

[0024] 1. The present invention uses PPS and core layer composite spinning, which greatly reduces the fiber cost without affecting the use of the product; the fluidity problem of PPS resin is the biggest factor affecting fiber yield and quality. The present invention introduces a flow promoter, which greatly improves the fluidity of the resin during the spinning process and at the same time improves the strength of the fiber, thereby improving the product qualification rate.

[0025] 2. In view of the fact that the ports of existing PPS / core layer composite fibers are exposed, that is, the corrosion resistance of the core layer material is not as good as that of PPS. Since it is exposed at the port, long-term use will affect its life. The present invention introduces an impregnation process after short cutting, so that the protective material is attached to the surface of the skin-core fiber port, and the non-corrosion-resistant core layer is wrapped and protected. After the fiber port is wrapped, the service life of the fiber is increased; and the effect of impregnation with conventional PTFE emulsion is not as good as the impregnation effect with modified PFA emulsion, and PFA emulsion is more corrosion-resistant.

[0026] 2. The present invention has simple process steps. The composite fiber produced by this process maintains the mechanical properties of the core material while maintaining the heat resistance and corrosion resistance of the PPS fiber. It also effectively reduces fiber costs. The PPS / core composite fiber with improved mechanical properties can meet practical application requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the skin-core structure of the PPS / PET composite fiber manufactured in Example 1 of the present invention before impregnation;

[0028] Figure 2 This is a schematic diagram of the preparation process of PPS / PET composite fibers according to Example 1 of the present invention. DETAILED DESCRIPTION

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. 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 making creative efforts shall fall within the scope of protection of the present invention.

[0030] Unless otherwise specified, the test materials and reagents used in the following examples can be obtained from commercial sources.

[0031] If no specific techniques or conditions are specified in the examples, they can be carried out according to the techniques or conditions described in the literature in the field or according to the product instructions.

[0032] The preparation method of the flow promoter and modified PFA emulsion used in the following specific embodiments is as follows:

[0033] 1. The preparation method of the flow promoter is as follows: add 10-20 parts of 3-5 carbon aliphatic alcohol, 20-40 parts of polydodecene, and 1-2 parts of dibutylhydroxytoluene into a reactor, and react for 5-8 hours under vacuum conditions with a vacuum degree of 50 Pa, a reaction temperature of 50-80°C, and a pressure of 0.2-0.5 MPa during the reaction.

[0034] 2. The preparation method of modified PFA emulsion is as follows: add a solvent and a crosslinker into a reactor, the solvent is deionized water, the crosslinker is 2,5-dimethyl-2,5-di-tert-butyl peroxide hexane, add 50-80 parts of deionized water, 1-5 parts of 2,5-dimethyl-2,5-di-tert-butyl peroxide hexane, 20-30 parts of PFA resin, 10-20 parts of fluorine-containing acrylate, the reaction temperature is 50-100°C, the reaction is carried out under vacuum, the vacuum degree is 50Pa, the reaction pressure is 2.0-2.5Mpa, the reaction is carried out for 2-3h, and 5-10 parts of polyvinylidene fluoride are added during the reaction.

[0035] Example 1:

[0036] The preparation method of the flow promoter is as follows:

[0037] Add 10 parts of 3-carbon fatty alcohol, 20 parts of polydodecene, and 1 part of butylated hydroxytoluene into the reactor, and react for 8 hours under vacuum conditions with a vacuum degree of 50 Pa, a reaction temperature of 50°C, and a pressure of 0.2 MPa during the reaction process;

[0038] The preparation method of modified PFA emulsion is as follows:

[0039] Add solvent and cross-linking agent into the reactor. The solvent is deionized water and the cross-linking agent is 2,5-dimethyl-2,5-di-tert-butyl peroxide hexane. Add 50 parts of deionized water, 1 part of 2,5-dimethyl-2,5-di-tert-butyl peroxide hexane, 20 parts of PFA resin, and 10 parts of fluorine-containing acrylate. The reaction temperature is 50°C. The reaction is carried out under vacuum with a vacuum degree of 50Pa and a reaction pressure of 2.0Mpa. The reaction is carried out for 3 hours. 5 parts of polyvinylidene fluoride are added during the reaction.

[0040] A method for preparing a PPS / PET composite fiber comprises the following steps:

[0041] (1) PPS and PET chips with a moisture content of less than 60 ppm were dried by vacuum drum drying for 12 hours at a temperature of 140°C.

[0042] The dried PET resin is screw-melted in a total of 5 melting temperature zones, with the first melting temperature zone at 240°C, the second melting temperature zone at 250°C, the third melting temperature zone at 260°C, the fourth melting temperature zone at 270°C, and the fifth melting temperature zone at 270°C;

[0043] 1% (by mass) of the flow promoter and the dried PPS were blended and then screw-melted in a total of 5 melting temperature zones, with the first melting temperature zone at 285°C, the second melting temperature zone at 295°C, the third melting temperature zone at 305°C, the fourth melting temperature zone at 315°C, and the fifth melting temperature zone at 305°C;

[0044] (2) The melted PET and PPS are passed through a bicomponent spinning beam and a composite spinneret for spinning, wherein the temperature of the PET spinning beam is controlled at 275°C, the temperature of the PPS spinning beam is controlled at 325°C, and the spinning speed is 800 m / min. When the composite spinneret is used for spinning, the composite ratio of PET and PPS is 5:5, with PPS as the skin layer and PET as the core layer;

[0045] The PPS / PET composite fiber was subjected to post-spinning drawing treatment, wherein the total drawing ratio was 3, the drawing temperature was 120°C, the setting temperature was 180°C, and the drawing speed was 500m / min;

[0046] (3) The stretched fibers are chopped and placed in a liquid dipping tank. The solution in the tank is a modified PFA emulsion with a mass concentration of 10%. After dipping, the fibers are taken out and dried at a temperature of 150°C.

[0047] The skin-core structure of PPS / PET composite fiber before impregnation is as follows Figure 1 As shown in the figure, it can be seen that the fiber is an enlarged cross-section of the PPS / PET composite fiber, the inner circle is the core layer formed by PET, and the outer circle is the skin layer wrapped by PPS.

[0048] The performance of the PPS / PET composite fiber prepared in this embodiment was tested:

[0049]

[0050]

[0051] Example 2:

[0052] The difference between this embodiment and embodiment 1 is that the "modified PFA emulsion" in step (3) is replaced by "PTFE solution", and the rest is the same as embodiment 1.

[0053] Example 3: (PPS / PA6 composite fiber)

[0054] The difference between this embodiment and embodiment 1 is that "PET" is changed to "PA6", and the rest is the same as embodiment 1.

[0055] Example 4: (PPS / PA66 composite fiber)

[0056] The difference between this embodiment and embodiment 1 is that "PET" is changed to "PA66", and the rest is the same as embodiment 1.

[0057] Example 5: (PPS / PBT composite fiber)

[0058] The difference between this embodiment and embodiment 1 is that "PET" is changed to "PBT", and the rest is the same as embodiment 1.

[0059] Example 6:

[0060] The preparation method of the flow promoter is as follows:

[0061] Add 15 parts of 4-C atom fatty alcohol, 30 parts of polydodecene, and 1.5 parts of butylated hydroxytoluene into the reactor, and react for 6 hours under vacuum conditions with a vacuum degree of 50 Pa, a reaction temperature of 60°C, and a pressure of 0.3 MPa during the reaction process;

[0062] The preparation method of modified PFA emulsion is as follows:

[0063] Add solvent and cross-linking agent into the reactor. The solvent is deionized water and the cross-linking agent is 2,5-dimethyl-2,5-di-tert-butyl peroxide hexane. Add 60 parts of deionized water, 3 parts of 2,5-dimethyl-2,5-di-tert-butyl peroxide hexane, 25 parts of PFA resin, and 15 parts of fluorine-containing acrylate. The reaction temperature is 65°C. The reaction is carried out under vacuum with a vacuum degree of 50Pa and a reaction pressure of 2.2Mpa. The reaction is carried out for 2.5 hours. During the reaction, 8 parts of polyvinylidene fluoride are added.

[0064] A method for preparing a PPS / PET composite fiber comprises the following steps:

[0065] (1) PPS and PET chips with a moisture content of less than 60 ppm were dried by vacuum drum drying for 14 hours at a temperature of 120°C.

[0066] The dried PET resin is screw-melted in a total of 5 melting temperature zones, with the first melting temperature zone at 240°C, the second melting temperature zone at 250°C, the third melting temperature zone at 260°C, the fourth melting temperature zone at 270°C, and the fifth melting temperature zone at 270°C;

[0067] 0.5% (by mass) of the flow promoter and the dried PPS were blended and then screw-melted in a total of 5 melting temperature zones, with the first melting temperature zone at 285°C, the second melting temperature zone at 295°C, the third melting temperature zone at 305°C, the fourth melting temperature zone at 315°C, and the fifth melting temperature zone at 305°C;

[0068] (2) The melted PET and PPS are passed through a two-component spinning beam and a composite spinneret for spinning, wherein the temperature of the PET spinning beam is controlled at 258°C, the temperature of the PPS spinning beam is controlled at 300°C, and the spinning speed is 600 m / min. When the composite spinneret is used for spinning, the composite ratio of PET and PPS is 4:6, with PPS as the skin layer and PET as the core layer;

[0069] The PPS / PET composite fiber was subjected to post-spinning drawing treatment, wherein the total drawing ratio was 2.5, the drawing temperature was 80°C, the setting temperature was 150°C, and the drawing speed was 800m / min;

[0070] (3) The stretched fibers are chopped and placed in a liquid immersion tank. The solution in the tank is a modified PFA emulsion with a mass concentration of 15%. After immersion, the fibers are taken out and dried at a temperature of 120°C.

[0071] Example 7:

[0072] The preparation method of the flow promoter is as follows:

[0073] Add 20 parts of 5-carbon fatty alcohol, 40 parts of polydodecene, and 2 parts of butylated hydroxytoluene into the reactor, and react for 5 hours under vacuum conditions with a vacuum degree of 50 Pa, a reaction temperature of 80°C, and a pressure of 0.5 MPa during the reaction.

[0074] The preparation method of modified PFA emulsion is as follows:

[0075] Add solvent and cross-linking agent into the reactor. The solvent is deionized water and the cross-linking agent is 2,5-dimethyl-2,5-di-tert-butyl peroxide hexane. Add 80 parts of deionized water, 5 parts of 2,5-dimethyl-2,5-di-tert-butyl peroxide hexane, 30 parts of PFA resin, and 20 parts of fluorine-containing acrylate. The reaction temperature is 100°C. The reaction is carried out under vacuum with a vacuum degree of 50Pa and a reaction pressure of 2.5Mpa. The reaction is carried out for 2 hours. During the reaction, 10 parts of polyvinylidene fluoride are added.

[0076] A method for preparing a PPS / PET composite fiber comprises the following steps:

[0077] (1) PPS and PET chips with a moisture content of less than 60 ppm were dried by vacuum drum drying for 12 hours at a temperature of 150°C;

[0078] The dried PET resin is screw-melted in a total of 5 melting temperature zones, with the first melting temperature zone at 240°C, the second melting temperature zone at 250°C, the third melting temperature zone at 260°C, the fourth melting temperature zone at 270°C, and the fifth melting temperature zone at 270°C;

[0079] 2% (by mass) of the flow promoter and the dried PPS were blended and then screw-melted in a total of 5 melting temperature zones, with the first melting temperature zone at 285°C, the second melting temperature zone at 295°C, the third melting temperature zone at 305°C, the fourth melting temperature zone at 315°C, and the fifth melting temperature zone at 305°C;

[0080] (2) The melted PET and PPS are passed through a bicomponent spinning beam and a composite spinneret for spinning, wherein the temperature of the PET spinning beam is controlled at 260°C, the temperature of the PPS spinning beam is controlled at 315°C, and the spinning speed is 600 m / min. When the composite spinneret is used for spinning, the composite ratio of PET and PPS is 6:4, with PPS as the skin layer and PET as the core layer;

[0081] The PPS / PET composite fiber was subjected to post-spinning drawing treatment, wherein the total drawing ratio was 3.5, the drawing temperature was 100°C, the setting temperature was 160°C, and the drawing speed was 600m / min;

[0082] (3) The stretched fibers are chopped and placed in a liquid immersion tank. The solution in the tank is a modified PFA emulsion with a mass concentration of 20%. After immersion, the fibers are taken out and dried at a temperature of 135°C.

[0083] Comparative Example 1: (Compared with Example 1, only PPS was used for spinning, without forming a skin-core structure)

[0084] (1) PPS slices with a moisture content of less than 60 ppm were dried by vacuum drum drying for 12 hours at a temperature of 140°C;

[0085] (2) 1% (by mass) of the flow promoter and the dried PPS were blended and then screw-melted, with a total of 5 melting temperature zones, the first melting temperature zone being at 285°C, the second melting temperature zone being at 295°C, the third melting temperature zone being at 305°C, the fourth melting temperature zone being at 315°C, and the fifth melting temperature zone being at 305°C;

[0086] (3) The melted PPS is spun through a spinning manifold, the temperature of the PPS spinning manifold is controlled at 325°C, and the spinning speed is 800 m / min;

[0087] (4) The PPS fiber was subjected to post-spinning drawing treatment, wherein the total drawing ratio was 3, the drawing temperature was 120°C, the setting temperature was 180°C, and the drawing speed was 500 m / min;

[0088] (5) The stretched fibers are chopped and placed in a liquid dipping tank. The solution in the tank is a modified PFA emulsion with a concentration of 10%. After dipping, the fibers are taken out and dried at a temperature of 150°C.

[0089] Comparative Example 2: (Compared with Example 1, other steps remain unchanged, and the 1% flow promoter is not added. The comparison proves the effect of the 1% flow promoter)

[0090] (1) PPS and PET chips with a moisture content of less than 60 ppm were dried by vacuum drum drying for 12 hours at a temperature of 140°C.

[0091] (2) screw melting the dried PET resin, with a total of 5 melting temperature zones, the first melting temperature zone having a temperature of 240°C, the second melting temperature zone having a temperature of 250°C, the third melting temperature zone having a temperature of 260°C, the fourth melting temperature zone having a temperature of 270°C, and the fifth melting temperature zone having a temperature of 270°C;

[0092] (3) After the dried PPS is blended, it is screw-melted with a total of 5 melting temperature zones, with the first melting temperature zone at 285°C, the second melting temperature zone at 295°C, the third melting temperature zone at 305°C, the fourth melting temperature zone at 315°C, and the fifth melting temperature zone at 305°C;

[0093] (4) The melted PET and PPS are passed through a bicomponent spinning beam and a composite spinneret for spinning, wherein the temperature of the PET spinning beam is controlled at 275°C, the temperature of the PPS spinning beam is controlled at 325°C, and the spinning speed is 800 m / min. When the composite spinneret is used for spinning, the composite ratio of PET and PPS is 5:5, with PPS as the skin layer and PET as the core layer;

[0094] (5) The PPS / PET composite fiber was subjected to post-spinning drawing treatment, wherein the total drawing ratio was 3, the drawing temperature was 120°C, the setting temperature was 180°C, and the drawing speed was 500 m / min;

[0095] (6) The stretched fibers are chopped and placed in a liquid dipping tank. The solution in the tank is a modified PFA emulsion with a concentration of 10%. After dipping, the fibers are taken out and dried at a temperature of 150°C.

[0096] Comparative Example 3 (Compared with Example 1, other steps remain unchanged, and after the short-cut treatment, no impregnation treatment is performed. The comparison proves the effect of impregnation wrapping the core-shell port)

[0097] (1) PPS and PET chips with a moisture content of less than 60 ppm were dried by vacuum drum drying for 12 hours at a temperature of 140°C.

[0098] (2) screw melting the dried PET resin, with a total of 5 melting temperature zones, the first melting temperature zone having a temperature of 240°C, the second melting temperature zone having a temperature of 250°C, the third melting temperature zone having a temperature of 260°C, the fourth melting temperature zone having a temperature of 270°C, and the fifth melting temperature zone having a temperature of 270°C;

[0099] (3) 1% flow promoter and dried PPS were blended and then screw-melted, with a total of 5 melting temperature zones, the first melting temperature zone at 285°C, the second melting temperature zone at 295°C, the third melting temperature zone at 305°C, the fourth melting temperature zone at 315°C, and the fifth melting temperature zone at 305°C;

[0100] (4) The melted PET and PPS are passed through a bicomponent spinning beam and a composite spinneret for spinning, wherein the temperature of the PET spinning beam is controlled at 275°C, the temperature of the PPS spinning beam is controlled at 325°C, and the spinning speed is 800 m / min. When the composite spinneret is used for spinning, the composite ratio of PET and PPS is 5:5, with PPS as the skin layer and PET as the core layer;

[0101] (5) The PPS / PET composite fiber was subjected to post-spinning drawing treatment, wherein the total drawing ratio was 3, the drawing temperature was 120°C, the setting temperature was 180°C, and the drawing speed was 500 m / min;

[0102] (6) The stretched fibers are chopped.

[0103] Comparative Example 4 (Compared with Example 1, other steps remain unchanged, and after the short-cut treatment, the mixture is impregnated with PFA emulsion)

[0104] (1) PPS and PET chips with a moisture content of less than 60 ppm were dried by vacuum drum drying for 12 hours at a temperature of 140°C.

[0105] (2) screw melting the dried PET resin, with a total of 5 melting temperature zones, the first melting temperature zone having a temperature of 240°C, the second melting temperature zone having a temperature of 250°C, the third melting temperature zone having a temperature of 260°C, the fourth melting temperature zone having a temperature of 270°C, and the fifth melting temperature zone having a temperature of 270°C;

[0106] (3) 1% flow promoter and dried PPS were blended and then screw-melted, with a total of 5 melting temperature zones, the first melting temperature zone at 285°C, the second melting temperature zone at 295°C, the third melting temperature zone at 305°C, the fourth melting temperature zone at 315°C, and the fifth melting temperature zone at 305°C;

[0107] (4) The melted PET and PPS are passed through a bicomponent spinning beam and a composite spinneret for spinning, wherein the temperature of the PET spinning beam is controlled at 275°C, the temperature of the PPS spinning beam is controlled at 325°C, and the spinning speed is 800 m / min. When the composite spinneret is used for spinning, the composite ratio of PET and PPS is 5:5, with PPS as the skin layer and PET as the core layer;

[0108] (5) The PPS / PET composite fiber was subjected to post-spinning drawing treatment, wherein the total drawing ratio was 3, the drawing temperature was 120°C, the setting temperature was 180°C, and the drawing speed was 500 m / min;

[0109] (6) The stretched fibers are chopped and placed in a liquid dipping tank containing a PFA emulsion with a concentration of 10%. After dipping, the fibers are taken out and dried at a temperature of 150°C.

[0110] Test method:

[0111] Take three fibers from each embodiment or comparative example for testing and take the average value:

[0112] 1. Strength test: Use electronic single fiber strength tester to test;

[0113] 2. Corrosion resistance test: According to the standard of GB / T6719-2009 "Technical Requirements for Bag Dust Collectors", the corrosion resistance test was carried out using 60% H2SO4 and 40% NaOH solutions respectively;

[0114] 3. Molten resin flow performance test: According to the GB / T 3682-2018 method, the melt index of PPS and PPS-1% flow promoter blend were tested using a melt index meter.

[0115] The test data is as follows:

[0116]

[0117]

[0118] It can be seen from the test data that the melt index of the PPS tested in Comparative Example 2 is 159 g / 10 min, and the melt index measured after adding 1% flow promoter to PPS in Example 1 is 202 g / 10 min, and the fiber strength test data produced in step 3 of Comparative Example 2 without adding flow promoter is 2.7 cN, while the data of Example 1 is 3.5 cN, that is, the strength of the fiber of Comparative Example 2 is lower than the strength of the fiber of Example 1. The reason is that in the process of spinning through the composite spinneret of the two-component spinning manifold, due to the poor fluidity of PPS after melting, the skin layer PPS wrapped around the outside of the PET core layer is unevenly distributed, which reduces the strength of the prepared fiber. In Example 1, the addition of 1% flow promoter solves the problem of poor fluidity of the molten PPS, so that the skin layer PPS is evenly wrapped around the outside of the PET core layer, and thus the strength of the fiber is higher.

[0119] The fiber strength test result of Example 2 is 3.2 cN, the strength test result of Example 1 is 3.5 cN, the strength of Comparative Example 3 is 3.0 cN, and the strength test result of Comparative Example 4 is 3.0 cN. The difference between Example 1, Example 2, Comparative Example 3 and Comparative Example 4 is only the impregnation part of step 6. Example 1 is impregnated with modified PFA emulsion, Example 2 is impregnated with PTFE emulsion, Comparative Example 3 is not impregnated with emulsion, and Comparative Example 4 is impregnated with PFA emulsion. It can be seen that the strength of the fiber is improved after being impregnated with the modified PFA emulsion prepared according to the present application, and the improvement is greater than that of the PTFE emulsion. There is no improvement in strength when simply impregnated with PFA emulsion.

[0120] The addition ratios of PET:PPS in Example 6 and Example 7 are different. The single fiber strength of Example 7 is higher than that of Example 6. The reason is that the proportion of PET in Example 7 is higher than that in Example 6, and the strength of PET resin is higher than that of PPS resin.

[0121] The strength of each fiber after being treated with 60% H2SO4 for 24 hours and 40% NaOH for 24 hours: the fiber of Example 1 was impregnated with modified PFA emulsion, and its fiber strength remained unchanged after acid and alkali treatment; the fiber of Example 2 was impregnated with PTFE emulsion, and its fiber strength after acid and alkali treatment was slightly reduced; the fiber of Comparative Example 3 was not impregnated with emulsion, and its fiber strength after acid and alkali treatment was significantly reduced; the fiber of Comparative Example 4 was impregnated with PFA emulsion, and its fiber strength after acid and alkali treatment was significantly reduced; it can be seen that after being impregnated with the modified PFA emulsion of this application, the skin-core fiber has a good effect of resisting acid and alkali corrosion. Analysis of the reasons: Comparative Example 3 was not impregnated with emulsion. After acid and alkali immersion, the core layer of PET would be corroded, resulting in a decrease in fiber strength; the PTFE in Example 2 itself has acid and alkali resistance. After the fiber was impregnated with PTFE emulsion, a PTFE film was formed on the fiber surface. However, after acid and alkali treatment, the strength of the fiber was still slightly reduced. The reason was that there were holes in the PTFE film formed on the fiber surface. The acid and alkali solutions penetrated into the ends of the core-skin fiber through the holes, corroding the core layer of PET, resulting in a decrease in fiber strength; Comparative Example 4 was impregnated with PFA emulsion, which had poor film-forming properties, resulting in the core layer of PET being corroded by acid and alkali; while the modified PFA emulsion impregnated in Example 1 formed a dense film, which wrapped and protected the core-skin fiber, avoiding acid and alkali penetration corrosion, and thus keeping the fiber strength unchanged after acid and alkali treatment.

[0122] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for preparing a polyphenylene sulfide composite fiber, characterized in that: The following steps are involved: (1) PPS and a core layer material are dried and melted separately; a flow promoter is added to the PPS during the melting process; the core layer material is at least one of PET, PA6, PA66, and PBT; (2) spinning and compounding the melted PPS and core layer material to obtain skin layer PPS / core layer composite fiber, and then performing a drafting process; (3) After the stretching, the skin PPS / core composite fiber is chopped and placed in an immersion tank for immersion. After immersion, it is taken out and dried to obtain the obtained fiber; the solution in the immersion tank is PTFE emulsion or modified PFA emulsion.

2. The method for preparing polyphenylene sulfide composite fiber according to claim 1, characterized in that: The drying temperature in step (1) is 120° C. to 150° C., and the drying time is 12 hours or more.

3. The method for preparing polyphenylene sulfide composite fiber according to claim 1, characterized in that: The proportion of the flow promoter added in step (1) is 0.5-2% of the mass of PPS.

4. The method for preparing polyphenylene sulfide composite fiber according to claim 1, characterized in that: The preparation method of the flow promoter comprises the following steps: adding 10 to 20 parts of 3 to 5 carbon atom fatty alcohol, adding 20 to 40 parts of polydodecene, and 1 to 2 parts of dibutylhydroxytoluene into a reaction kettle, reacting for 5 to 8 hours under vacuum conditions, the vacuum degree is 50 Pa, the reaction temperature is controlled at 50 to 80° C., and the pressure during the reaction process is 0.2 to 0.5 MPa.

5. The method for preparing polyphenylene sulfide composite fiber according to claim 1, characterized in that: In the step (2), the PPS spinning temperature is controlled at 300-325° C., the core layer spinning temperature is controlled at 258-275° C., and the spinning speed is 600-800 m / min.

6. The method for preparing polyphenylene sulfide composite fiber according to claim 1, characterized in that: The mass ratio of PPS to the core layer in the step (2) is (4-6):(6-4); the drawing ratio in the step (2) is 2.5-3.5, the drawing temperature is 80-120° C., the setting temperature is 150-180° C., and the drawing speed is 500-800 m / min.

7. The method for preparing polyphenylene sulfide composite fiber according to claim 1, characterized in that: The mass percentage concentration of the PTFE emulsion or the modified PFA emulsion in step (3) is 10-20%; the preparation method of the modified PFA emulsion, The following steps are involved: Add a solvent and a cross-linking agent into a reactor, wherein the solvent is deionized water and the cross-linking agent is 2,5-dimethyl-2,5-di-tert-butyl peroxide hexane. Add 50-80 parts of deionized water, 1-5 parts of 2,5-dimethyl-2,5-di-tert-butyl peroxide hexane, 20-30 parts of PFA resin, and 10-20 parts of fluorine-containing acrylate. The reaction temperature is 50-100° C. and the reaction is carried out under vacuum with a vacuum degree of 50 Pa and a reaction pressure of 2.0-2.5 MPa. The reaction is carried out for 2-3 hours. During the reaction, 5-10 parts of polyvinylidene fluoride are added.

8. The method for preparing polyphenylene sulfide composite fiber according to claim 1, characterized in that: The drying temperature in step (3) is 120-150°C.

9. The polyphenylene sulfide composite fiber obtained by the preparation method according to any one of claims 1 to 8.

10. Use of the polyphenylene sulfide composite fiber according to claim 9 as an air filter material.

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