Process for the preparation of long-lasting antistatic polypropylene fibers

Abstract

The application provides a preparation method of long-acting antistatic polypropylene fibers, comprising powder graft modification, preparation of a high-molecular antistatic agent, preparation of a conductive master batch, and preparation of conductive polypropylene fibers. The application successfully prepares a poly-caprolactam-polyether high-molecular permanent antistatic agent through in-situ melt copolymerization, and combines with modified inorganic powder to form a multi-dimensional conductive network structure, so that the charge freely flows in the conductive network, effectively reducing the resistivity. The obtained polypropylene fibers have good antistatic performance, the effect is long-lasting, are not affected by air humidity and wiping and washing, and have good mechanical properties.

Description

Technical Field

[0001] This invention relates to the field of synthetic fibers, and in particular to a method for preparing long-lasting antistatic polypropylene fibers. Background Technology

[0002] Polypropylene (PP) fiber has the lowest density among all chemical fibers, and it is frequently used to make lightweight clothing. However, polypropylene molecules lack hydrophilic groups, resulting in poor moisture absorption. Its fiber products are prone to pilling, and after frictional charging, static electricity is difficult to remove through conductivity and remains on the material surface. This not only affects the material's appearance, manufacturing, and use, but more importantly, it poses electrostatic safety hazards, severely limiting its applications in petrochemicals, coal mining, precision machinery, integrated circuit manufacturing, and electronic communications.

[0003] To eliminate static electricity, metal-based conductive fillers or surfactants are often added to polypropylene fibers to reduce surface resistance and volume resistance, thereby expanding the range of applications. However, the addition of fillers usually has problems such as poor compatibility, easy precipitation, and color deterioration; the addition of surfactants is easy to cause the surface antistatic agent to gradually disappear with wiping or washing during use, and the internal antistatic agent molecules continuously migrate to the surface until they are completely consumed. The effect of antistatic agent has a certain time range and is not permanent. In addition, the presence of antistatic agent will also reduce the mechanical properties of the fiber to a certain extent, affecting its application effect. In order to improve the antistatic properties of polypropylene nonwoven fabric, Professor Wei Chunyan's research group at Dalian University of Technology used graphene oxide as a grafting monomer and optimized the process parameters of grafting graphene oxide onto polypropylene nonwoven fabric by response surface methodology. The triboelectric voltage of the grafted polypropylene nonwoven fabric was 1094V, but its surface was rough and its color deteriorated. (Journal of Textile Research, 2019, 40(11): 125-130). Mao Zhihua disclosed a method for preparing nano-magnesium oxide-graphene-polypropylene composite fibers, which provides a method for preparing nano-magnesium oxide-graphene-polypropylene composite fibers. The prepared polypropylene fibers have a smooth surface and good antistatic properties. However, this method cannot overcome the compatibility problem between the resin and the filler, and the antistatic agent has poor antistatic effect in dry northern weather.

[0004] In view of this, the inventor of this case conducted in-depth research, which led to the creation of this case. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing long-lasting antistatic polypropylene fibers that solves the problems of poor compatibility, easy migration to the matrix surface, and short-lived antistatic effect of antistatic agents.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A method for preparing long-lasting antistatic polypropylene fiber includes the following steps:

[0008] Step 1, Preparation of modified powder: Inorganic oxides are dispersed in an organic solvent containing a coupling agent, the reaction atmosphere is controlled, the mixture is stirred and subjected to a first temperature-controlled reaction; then the copolymer is added, and a second temperature-controlled reaction is carried out to obtain the modified powder;

[0009] Step 2, Preparation of polymeric antistatic agent: Caprolactam, polyether, deionized water, end-capping agent, water absorbent, and catalyst are mixed in a certain proportion and then subjected to melting, esterification, and polycondensation reactions in sequence to obtain a polymeric permanent antistatic agent;

[0010] Step 3, Preparation of conductive masterbatch: The modified powder obtained in Step 1 and the polymeric antistatic agent obtained in Step 2 are vacuum dried; then, polypropylene, antioxidant, compatibilizer, dispersant, lubricant, and the vacuum-dried modified powder and polymeric antistatic agent are mixed evenly in a certain proportion, and then melt-extruded, cooled and granulated to obtain conductive masterbatch.

[0011] Step 4, Spinning of conductive fibers: The conductive masterbatch obtained in step 3 is melted and extruded through a spinneret, wound, stretched on a hot plate and heat-set to obtain conductive fibers.

[0012] Further, in step 1: by mass ratio, the inorganic oxide: the organic solvent: the coupling agent: the copolymer = 1:15:0.1:0.1 to 1:30:0.7:5;

[0013] The inorganic oxide is one or a combination of two or more of titanium dioxide, silicon dioxide, and zirconium dioxide; the copolymer is one or a combination of two or more of ethylene-vinyl acetate block copolymer, polyethylene, and polypropylene; the coupling agent is one or a combination of two or more of KH-550, KH560, KR-TTS, KR-38S, 3-methoxypropyltrimethoxysilane, and 3-methoxypropyltriethoxysilane; and the reaction solvent is one or a combination of two or more of toluene, ethanol, and petroleum ether.

[0014] Further, in step 1: the reaction atmosphere is N2 or Ar, the reaction temperature of the first temperature-controlled reaction is 100-130°C, and the reaction time is 1-3h; in the second temperature-controlled reaction stage, the system after the first temperature-controlled reaction is first cooled to 30-60°C, and then the copolymer is added, and the reaction continues for 0.5-2h.

[0015] Further, in step 2: by mass ratio, the caprolactam: the polyether: the deionized water: the water absorbent: the end-capping agent: the catalyst = 20:100:1:1:0.1:0.01 = 100:20:10:10:5:5;

[0016] The polyether is polyethylene oxide and / or polytetrahydrofuran; the end-capping agent is one or a combination of two or more of adipic acid, sebacic acid, hexanoic acid, and benzoic acid; the water-absorbing agent is concentrated sulfuric acid; and the catalyst is one or a combination of two or more of antimony glycolate, antimony trioxide, and antimony acetate.

[0017] Furthermore, in step 2: during the melting process, the atmosphere is controlled to be N2 or Ar, the reaction temperature is controlled to be 200-260℃, and the time is controlled to be 0.2-1h.

[0018] Furthermore, in step 2: the esterification stage includes pre-esterification and post-esterification. In the pre-esterification, after the material melts, caprolactam begins to undergo esterification reaction, with the temperature controlled at 220-270°C and the time at 0.2-1h. In the post-esterification, the vacuum degree is controlled at 500-1000Pa, the temperature is controlled at 210-250°C, and the time at 1-3h.

[0019] Furthermore, in step 2: during the polycondensation, the vacuum level is controlled to be 100-500 Pa, and the reaction time is 0.5-2 h.

[0020] Further, in step 3: by weight ratio, the polypropylene: the modified powder: the polymeric antistatic agent: the antioxidant: the compatibilizer: the dispersant: the lubricant = 20:1:1:0.1:0.1:0.1:0.1~30:5:10:2:3:2:2;

[0021] Further, in step 3: the antioxidant is one or more of antioxidant 1010, antioxidant 1076, antioxidant 168, antioxidant PEPQ, and antioxidant 626; the compatibilizer is maleic anhydride-grafted polypropylene and / or ethylene vinyl acetate-grafted maleic anhydride; the lubricant is one or more of polyethylene wax, fatty acids, and stearic acid; the dispersant is one or a combination of two or more of polyacrylamide, polyacrylamide, polyvinyl alcohol, ethylenediaminetetramethylenephosphonic acid, and hydroxyethylidene diphosphate.

[0022] Furthermore, in step 3: during melt extrusion, the temperature range of the melt extrusion equipment is 170–260°C, the screw pressure is 0.05–1 MPa, the screw rotation speed is 30–120 rpm, and the pelletizing speed is 10–100 rpm; during cooling, water cooling is used.

[0023] Furthermore, in step 4: the spinning temperature is 150–200°C; the hot plate stretching temperature is 70–150°C, and the stretching ratio is 2–6 times; the heat setting temperature is 70–150°C, and the time is 0.1–1 h.

[0024] The present invention provides a method for preparing long-lasting antistatic polypropylene fiber using the above technical solution, which has the following beneficial effects: Inorganic powder modification improves the dispersibility of conductive materials in the polypropylene fiber. A one-step melt in-situ copolymerization process prepares a polycaprolactam-polyether type permanent antistatic agent, which, in conjunction with the modified powder, forms a multidimensional conductive network structure within the polypropylene matrix. This network serves as a pathway for charge leakage, reducing resistance and improving the fiber's antistatic performance. Compared to other traditional antistatic agents, the antistatic polypropylene fiber of the present invention does not rely on surface water absorption, thus being less affected by humidity. The antistatic agent of the present invention has a large molecular weight and forms a multidimensional conductive network structure within the matrix, preventing easy migration to the matrix surface. It is less affected by washing and wiping, resulting in a longer-lasting antistatic effect. The surface resistivity changes little after dozens of water washes (e.g., 40 washes) and dozens of dry frictions (e.g., 60 dry frictions). Furthermore, the modified powder is uniformly dispersed in the polypropylene fiber, providing reinforcement and filling effects, and improving the weather resistance of the fiber product. Even after aging treatment, it maintains good overall performance.

[0025] Furthermore, the polycaprolactam-polyether type permanent antistatic agent, combined with grafted modified titanium dioxide, improves the dispersibility of conductive materials in polypropylene, forming a multidimensional conductive network structure inside the polypropylene matrix, constituting a conductive channel, and using this as a pathway to leak charge, effectively reducing resistivity.

[0026] Furthermore, a one-step in-situ melt copolymerization method was used to prepare a polymeric permanent antistatic agent. By controlling the amounts of end-capping agent, catalyst, and desiccant, as well as the vacuum level, and adjusting the appropriate soft-hard ratio of the polymer structure, a polymeric permanent antistatic agent with superior modification effect was obtained. Testing showed that the prepared polymeric permanent antistatic agent had a surface resistivity of 5.95 × 10⁻⁶. 7 Ω.

[0027] The present invention has a reasonable control of the soft-hard ratio of the polymer structure. The unreacted free polyethylene oxide (PEO) in the antistatic agent is dispersed in polypropylene. Some soft-end PEO and PP form a conductive water layer at the phase interface. Some PEO and grafted modified polypropylene are uniformly dispersed in the PP matrix to form conductive water channels from the inside out, which play a role in transferring charge.

[0028] The surface resistivity of the polypropylene fiber prepared in Example 3 was tested to be 5.91 × 10⁻⁶. 7 Ω, which can improve upon traditional pure polypropylene fiber (lacking numerous modifiers, etc.) by 5 orders of magnitude. Attached Figure Description

[0029] Figure 1 This is a performance characterization diagram of the antistatic polypropylene fiber of Example 3 of the present invention. Detailed Implementation

[0030] To further explain the technical solution of the present invention, the present invention will be described in detail below through specific embodiments.

[0031] The present invention will be further described in detail below with reference to the accompanying drawings: a permanent antistatic agent of polycaprolactam (hard segment)-polyether (soft end) type is prepared by one-step melt in-situ cocondensation. By adjusting the ratio between hard segment and soft end, and combining with other functional additives, the agent is extruded and granulated, and then melt-spun to obtain long-lasting antistatic polypropylene fiber.

[0032] I. Preparation Method

[0033] Example 1

[0034] This invention discloses a method for preparing long-lasting antistatic polypropylene fiber, comprising the following steps:

[0035] Step 1: Disperse the coupling agent isopropyltris(dioctylpyrophosphoryl)titanate (KR-38S) in toluene solvent to obtain solution A. Disperse titanium dioxide in solution A, control the reaction atmosphere as N2, the reaction temperature as 90℃, and the reaction time as 2h to obtain solution B. Cool the temperature to 50℃, add EVA, and continue the reaction for 1h. Filter and dry to obtain modified powder for later use. The mass ratio of titanium dioxide:toluene:coupling agent:EVA is 1:18:0.5:1.1.

[0036] In step 1 of this invention, in addition to the aforementioned substances, the inorganic oxide, copolymer, coupling agent, and reaction solvent may also specifically employ the following substances and combinations: the inorganic oxide is one or a combination of two or more of titanium dioxide, silicon dioxide, and zirconium dioxide; the copolymer is one or a combination of two or more of ethylene-vinyl acetate block copolymer, polyethylene, and polypropylene; the coupling agent is one or a combination of two or more of KH-550, KH560, isopropyltris(isostearoyl)titanate (KR-TTS), isopropyltris(dioctylpyrophosphoryl)titanate (KR-38S), 3-methoxypropyltrimethoxysilane (MPTS), and 3-methoxypropyltriethoxysilane (MPEOS); and the reaction solvent is one or a combination of two or more of toluene, ethanol, and petroleum ether.

[0037] Step 2: Caprolactam, polyethylene oxide, deionized water, concentrated sulfuric acid, adipic acid, and antimony trioxide are added to a reaction vessel and subjected to melting, esterification, and polycondensation reactions sequentially. Melting stage: The atmosphere is controlled as N2, the reaction temperature is controlled at 220℃, and the time is 0.5 h. Esterification stage: In the early esterification stage, after the materials melt, caprolactam begins esterification, controlled at 245℃ for 0.6 h. In the later esterification stage, the vacuum degree is controlled at 750 Pa, the temperature at 230℃, and the reaction time is 2 h. Polycondensation stage: The vacuum degree is controlled at 200 Pa, and the reaction time is 1.2 h. The mass ratio of caprolactam: polyethylene oxide: deionized water: concentrated sulfuric acid: adipic acid: antimony trioxide is 70:30:2:1:0.06:0.07. A polymeric antistatic agent is obtained.

[0038] In step 2 of this invention, in addition to the aforementioned polyethylene oxide, the polyether may also be polytetrahydrofuran, or a combination of polyethylene oxide and polytetrahydrofuran; in addition to adipic acid, the end-capping agent may also be one or a combination of two or more of adipic acid, sebacic acid, hexanoic acid, and benzoic acid; in addition to the aforementioned antimony trioxide, the catalyst may also be one or a combination of two or more of antimony glycolate, antimony trioxide, and antimony acetate.

[0039] In step 2 of this invention, the atmosphere can also be controlled to be Ar during the melting stage.

[0040] Step 3: Vacuum dry the polymeric antistatic agent, modified powder, and compatibilizer at 80℃ for 1 hour. Add the polypropylene, modified powder, polymeric antistatic agent, antioxidant 168, compatibilizer (ethylene vinyl acetate grafted maleic anhydride), dispersant (polyacrylamide), and lubricant (polyethylene wax) to a high-speed mixer for pre-dispersion. Then, add the mixture to a twin-screw extruder. The extruder zones 1-6 temperatures are 200℃, 210℃, 220℃, 220℃, 230℃, and 230℃, respectively. The screw pressure is 0.5 MPa, the screw speed is 80 rpm, and the pelletizing speed is 60 rpm. Water cooling is then performed to obtain conductive masterbatch. The ratio of polypropylene: modified powder: polymeric antistatic agent: antioxidant: compatibilizer: dispersant: lubricant is 100:15:10:0.1:4:1:1.

[0041] In step 3 of this invention, in addition to antioxidant 168, the antioxidant may also be one or a combination of two or more of antioxidants 1010, 1076, 168, PEPQ, and 626. The compatibilizer may also be maleic anhydride-grafted polypropylene, or a combination of ethylene vinyl acetate-grafted maleic anhydride and maleic anhydride-grafted polypropylene, in addition to ethylene wax. The lubricant may also be polyethylene wax, or a combination of one or more of polyethylene wax, fatty acids, and stearic acid, in addition to polyacrylamide. The dispersant may also be polyacrylamide, polyacrylamide, polyvinyl alcohol, ethylenediaminetetramethylenephosphonic acid, and hydroxyethylidene diphosphate, in addition to polyacrylamide.

[0042] Step 4: After vacuum drying the conductive masterbatch at 80℃ for 5 hours, place it in a spinning machine. The heating temperatures are set as follows: Zone 1 190℃, Zone 2 210℃, Zone 3 200℃; winding speed 150 m / min; hot plate stretching temperature 135℃, stretching ratio 3.5 times; heat setting temperature 85℃, time 0.5 hours, to obtain long-lasting antistatic polypropylene fiber. The performance characterization of the long-lasting antistatic polypropylene fiber is as follows... Figure 1 As shown.

[0043] In this invention, all materials used are commercially available products.

[0044] This invention discloses a method for preparing long-lasting antistatic polypropylene fiber. The method involves preparing a polycaprolactam (hard segment)-polyether (soft end) type permanent antistatic agent through one-step melt in-situ copolymerization. By adjusting the ratio between the hard segment and the soft end, and combining it with other functional additives, the fiber is extruded and granulated, and then melt-spun to obtain long-lasting antistatic polypropylene fiber.

[0045] Titanium dioxide was modified using coupling agents to improve its dispersibility and compatibility in polypropylene, enhance the reinforcing effect of inorganic powders, and simultaneously improve the UV aging resistance and weather resistance of fiber products. Modified titanium dioxide was grafted with EVA, which acts as a toughening agent in the polypropylene system, increasing the elongation at break of fiber products.

[0046] Example 2

[0047] This invention discloses a method for preparing long-lasting antistatic polypropylene fiber, comprising the following steps:

[0048] Step 1: Disperse coupling agent KH560 in toluene solvent to obtain solution A. Disperse titanium dioxide in solution A, control the reaction atmosphere as N2, the reaction temperature as 90℃, and the reaction time as 2h to obtain solution B. Cool the temperature to 45℃, add polypropylene, react for 1h, filter, and dry to obtain modified powder for later use. The mass ratio of titanium dioxide:toluene:coupling agent:EVA is 1:18:0.5:1.

[0049] Step 2: Caprolactam, polyethylene oxide, deionized water, concentrated sulfuric acid, adipic acid, and antimony trioxide are added to a reaction vessel and subjected to melting, esterification, and polycondensation reactions sequentially. Melting stage: The atmosphere is controlled as N2, the reaction temperature is controlled at 220℃, and the time is 0.5 h. Esterification stage: In the early esterification stage, after the materials melt, caprolactam begins esterification, controlled at 250℃ for 0.5 h. In the later esterification stage, the vacuum degree is controlled at 750 Pa, the temperature at 230℃, and the reaction time is 2 h. Polycondensation stage: The vacuum degree is controlled at 200 Pa, and the time is 1.2 h. The mass ratio of caprolactam:polytetrahydrofuran:deionized water:concentrated sulfuric acid:adipic acid:antimony trioxide is 30:70:2:1:0.06:0.07. A polymeric antistatic agent is obtained.

[0050] Step 3: Vacuum dry the polymeric antistatic agent, modified powder, and compatibilizer at 80℃ for 1 hour. Add the polypropylene, modified powder, polymeric antistatic agent, antioxidant 168, compatibilizer (maleic anhydride-grafted polypropylene), dispersant (polyacrylamide), and lubricant (polyethylene wax) to a high-speed mixer for pre-dispersion. Then, add the mixture to a twin-screw extruder. The extruder's zone temperatures (1-6) are 200℃, 210℃, 220℃, 220℃, 230℃, and 230℃, respectively. The screw pressure is 0.5 MPa, the screw speed is 80 rpm, and the pelletizing speed is 60 rpm. Water cooling is then performed to obtain conductive masterbatch. The ratio of polypropylene: modified powder: polymeric antistatic agent: antioxidant: compatibilizer: dispersant: lubricant is 100:15:10:0.1:4:1:1.

[0051] Step 4: After vacuum drying the conductive masterbatch at 80℃ for 5 hours, place it in a spinning machine. The heating temperature is set as follows: Zone 1 190℃, Zone 2 210℃, Zone 3 200℃, and the winding speed is 150m / min. The hot plate stretching temperature is 135℃, and the stretching ratio is 4 times. The heat setting temperature is 85℃, and the time is 0.5 hours to obtain long-lasting antistatic polypropylene fiber.

[0052] Example 3

[0053] This invention discloses a method for preparing long-lasting antistatic polypropylene fiber, comprising the following steps:

[0054] Step 1: Disperse the coupling agent isopropyltris(dioctylpyrophosphoryl)titanate (KR-38S) in toluene solvent to obtain solution A. Disperse titanium dioxide in solution A, control the reaction atmosphere as N2, the reaction temperature as 90℃, and the reaction time as 2h to obtain solution B. Cool the temperature to 45℃, add EVA, react for 1h, filter, and dry to obtain modified powder for later use. The mass ratio of titanium dioxide:toluene:coupling agent:EVA is 1:18:0.5:1.

[0055] Step 2: Caprolactam, polyethylene oxide, deionized water, concentrated sulfuric acid, adipic acid, and antimony trioxide are added to a reaction vessel and subjected to melting, esterification, and polycondensation reactions sequentially. Melting stage: The atmosphere is controlled as N2, the reaction temperature is controlled at 220℃, and the time is 0.5 h. Esterification stage: In the early esterification stage, after the materials melt, caprolactam begins esterification, controlled at 240℃ for 0.6 h. In the later esterification stage, the vacuum degree is controlled at 750 Pa, the temperature at 230℃, and the reaction time is 2 h. Polycondensation stage: The vacuum degree is controlled at 200 Pa, and the time is 1.2 h. The mass ratio of caprolactam: polyethylene oxide: deionized water: concentrated sulfuric acid: adipic acid: antimony trioxide is 40:60:2:1:0.06:0.07. A polymeric antistatic agent is obtained.

[0056] Step 3: Vacuum dry the polymeric antistatic agent, modified powder, and compatibilizer at 80℃ for 1 hour. Add the polypropylene, modified powder, polymeric antistatic agent, antioxidant 168, compatibilizer (ethylene vinyl acetate grafted maleic anhydride), dispersant (polyvinyl alcohol), and lubricant (polyethylene wax) to a high-speed mixer for pre-dispersion. Then, add the mixture to a twin-screw extruder. The extruder zones 1-6 temperatures are 200℃, 210℃, 220℃, 220℃, 230℃, and 230℃, respectively. The screw pressure is 0.5 MPa, the screw speed is 80 rpm, and the pelletizing speed is 60 rpm. Water cooling is then performed to obtain conductive masterbatch. The ratio of polypropylene: modified powder: polymeric antistatic agent: antioxidant: compatibilizer: dispersant: lubricant is 100:15:10:0.1:4:1:1.

[0057] Step 4: After vacuum drying the conductive masterbatch at 80℃ for 5 hours, place it in a spinning machine. The heating temperatures are set as follows: Zone 1 190℃, Zone 2 210℃, Zone 3 200℃; winding speed 150 m / min; hot plate stretching temperature 135℃, stretching ratio 3.5 times; heat setting temperature 85℃, time 0.5 hours, to obtain long-lasting antistatic polypropylene fiber. The performance characterization of the long-lasting antistatic polypropylene fiber is as follows: Figure 1 As shown.

[0058] In this embodiment, the soft-to-hard ratio of the polymer structure is 60:40, which is reasonably controlled. Unreacted free PEO in the antistatic agent is dispersed in the polypropylene. Some soft-end PEO and PP form a conductive water layer at the phase interface, while some PEO and grafted modified polypropylene are uniformly dispersed in the PP matrix, forming conductive water channels from the inside out, which play a role in charge transfer. Testing showed that the surface resistivity of the polypropylene fiber prepared in Example 3 is 5.91 × 10⁻⁶. 7 Ω.

[0059] Comparative Example 1

[0060] The preparation method of Example 3 was repeated according to the amount of each component, but in step 1, the coupling agent isopropyl tris(dioctyl pyrophosphoryl) titanate (KR-38S) was not added, that is, the addition of the coupling agent was omitted.

[0061] Comparative Example 2

[0062] The preparation method of Example 3 was repeated according to the amount of each component, but in step 1, titanium dioxide was not used and silicon dioxide was used instead.

[0063] Comparative Example 3

[0064] The preparation method of Example 3 was repeated according to the amount of each component, but in step 1, EVA was not added, that is, the addition of copolymer EVA was omitted.

[0065] Comparative Example 4

[0066] The preparation method of Example 3 was repeated according to the amount of each component, but in step 3, the modified powder was not added, that is, the addition of the modified powder was omitted.

[0067] Comparative Example 5

[0068] The preparation method of Example 3 was repeated according to the amount of each component, but in step 2, the mass ratio of caprolactam: polyethylene oxide: deionized water: concentrated sulfuric acid: adipic acid: antimony trioxide was 40:60:2:1:0:0.07.

[0069] Comparative Example 6

[0070] The preparation method of Example 3 was repeated according to the amount of each component, but in step 2, the mass ratio of caprolactam: polyethylene oxide: deionized water: concentrated sulfuric acid: adipic acid: antimony trioxide was 40:60:2:1:0.06:0.

[0071] In this comparative example, since the amount of antimony trioxide catalyst was 0, a polymeric antistatic agent could not be prepared.

[0072] Comparative Example 7

[0073] The preparation method of Example 3 was repeated according to the amount of each component, but in step 2, the mass ratio of caprolactam: polyethylene oxide: deionized water: concentrated sulfuric acid: adipic acid: antimony trioxide was 30:70:2:1:0.06:0.07.

[0074] Comparative Example 8

[0075] The preparation method of Example 3 was repeated according to the amount of each component, but in step 2, the mass ratio of caprolactam: polyethylene oxide: deionized water: concentrated sulfuric acid: adipic acid: antimony trioxide was 50:50:2:1:0.06:0.07.

[0076] Comparative Example 9

[0077] The preparation method of Example 3 was repeated according to the amount of each component, but the vacuum degree was controlled at 300 Pa during the esterification stage of step 2.

[0078] Comparative Example 10

[0079] The preparation method of Example 3 was repeated according to the amount of each component, but the vacuum degree was controlled at 700 Pa during the polycondensation stage of step 2.

[0080] Comparative Example 11

[0081] The preparation method of Example 3 was repeated according to the amount of each component, but the polymeric antistatic agent was not added in step 3, that is, the addition of the polymeric antistatic agent was omitted.

[0082] Comparative Example 12

[0083] The preparation method of Example 3 was repeated according to the amount of each component, but instead of adding a polymeric antistatic agent, an anionic antistatic agent MOA3PK was used.

[0084] Comparative Example 13

[0085] The preparation method of Example 3 was repeated according to the amount of each component, but in step 3, no compatibilizer was added, that is, the addition of compatibilizer was omitted.

[0086] Comparative Example 14

[0087] The preparation method of Example 3 was repeated according to the amount of each component, but in step 3, lubricant and dispersant were not added, that is, the addition of compatibilizer was omitted.

[0088] Comparative Example 15

[0089] The preparation method of Example 3 was repeated according to the amount of each component, but in step 4, the stretching ratio was 10 times.

[0090] Comparative Example 16

[0091] The preparation method of Example 3 is repeated according to the amount of each component, but in step 4, the heat setting operation is not performed, that is, the heat setting operation is omitted.

[0092] Comparative Example 17

[0093] Polypropylene was vacuum dried at 80℃ for 5 hours and then placed in a spinning machine. The heating temperature was set as follows: zone 1 190℃, zone 2 210℃, zone 3 200℃, and the winding speed was 150m / min. The hot plate stretching temperature was 135℃ and the stretching ratio was 3 times. The heat setting temperature was 85℃ and the time was 0.5 hours to obtain pure polypropylene fibers.

[0094] II. Performance Testing

[0095] (a) The obtained polymeric permanent antistatic agent was used to make standard dumbbell bars, and the following performance tests were conducted. The results are shown in Table 1 below:

[0096] (1) Mechanical properties:

[0097] According to GB / T17200-2008, polycaprolactam-polyether copolymer samples were molded into dumbbell-shaped and notched impact specimens by micro-injection molding. After being placed at room temperature for 48 hours to equilibrate, mechanical properties were tested using a universal testing machine. Tensile conditions: tensile rate 50 mm / min.

[0098] (2) Antistatic performance test:

[0099] Antistatic property test: According to GB / T1410-2006, after injection molding into round and rectangular sheets, the samples are tested using a resistivity tester.

[0100] Table 1 Performance Characterization of Polymer-Based Permanent Antistatic Agents

[0101]

[0102] (ii) The obtained antistatic polypropylene fibers were subjected to the following performance tests:

[0103] (1) Fiber strength

[0104] Tensile properties were tested using a yarn tensile elongation tester (Shanghai Xinxian Instrument Co., Ltd. XL-2 model). The distance between the clamps was 250 mm, the fiber pretension was 0.05 cN / dtex, and the stretching speed was 500 mm / min.

[0105] (2) Fiber resistance test

[0106] Referring to GB / T14342-2015, weigh 50g of fiber, stretch the fiber into a fluffy state, and place it under standard atmospheric pressure conditions (temperature 20±2℃, test humidity 65±5%). Calculate the fiber resistivity ρ according to formula (4-4). v .

[0107] ρ v＝ (R·B·H·f) / L

[0108] Where, ρ v Volume resistivity, in Ω·cm; R is the average fiber resistance, in Ω; B: effective length of electrode plate (4cm); H: electrode plate height (6cm); L: distance between the two electrode plates (2cm); f is the standard fill factor of the material being tested (0.35 for polypropylene).

[0109] (3) Humidity dependence test

[0110] The relative humidity of the air inside the sealed dryer was controlled using an air humidifier. Antistatic polypropylene fibers were placed under different humidity conditions for a certain number of minutes, and their surface resistivity (Ω) was measured. The results are shown in Table 4 below.

[0111] (4) Washability test

[0112] Antistatic polypropylene fiber samples were washed with tap water for 5 minutes each time. After different numbers of washes, the samples were removed, dried, and their resistivity was measured. The results are shown in Table 3 below.

[0113] (5) Durability test

[0114] Antistatic polypropylene fibers were placed at room temperature, and the change in their surface resistivity (Ω) was measured at regular intervals. The results are shown in Table 5 below.

[0115] (6) Dry friction test:

[0116] Under conditions of 20℃±2℃ and 65%±2% relative humidity, the fiber product was placed on waterproof sandpaper of a friction instrument, with cotton cloth wrapped around the tip of the friction head. The sample was rubbed 10 times along its length within 10 seconds, with a reciprocating stroke of 100mm and a vertical pressure of 9N. The surface resistivity (Ω) was measured after multiple dry rubbing operations. The results are shown in Table 6 below.

[0117] (7) UV protection

[0118] The fibers were placed in a UV aging chamber (without spraying), and the wavelength was set to 310 nm according to ASTM G-154 standard for 200 h. The results are shown in Table 2 below.

[0119] Table 2 Performance characterization of polypropylene fibers

[0120]

[0121]

[0122] Table 3. Water resistance test of polypropylene fiber

[0123]

[0124] Table 4. Moisture Dependence Test of Polypropylene Fiber

[0125]

[0126] Table 5. Durability test of polypropylene fiber

[0127]

[0128] Table 6 Dry Friction Test of Polypropylene Fiber

[0129]

[0130]

[0131] The results showed that the antistatic polypropylene fibers prepared in Examples 1, 2, and 3 exhibited good overall performance and durable antistatic properties. They were also less affected by factors such as humidity, friction, and washing. After 40 washes and 40 dry rubbing cycles, their surface resistivity did not increase significantly. They demonstrated good antistatic effects under various humidity conditions and good performance. In particular, compared to Examples 1 and 2, the antistatic polypropylene fiber prepared by the method in Example 3 showed even better overall performance. At a soft-to-hardness ratio of 60:40, the unreacted free PEO in the antistatic agent was dispersed in the polypropylene. Some of the soft-end PEO and PP formed a conductive water layer at the phase interface, while some PEO and grafted modified polypropylene were uniformly dispersed in the PP matrix, forming conductive water channels from the inside out. The resulting fiber membrane exhibited the best antistatic performance.

[0132] In Comparative Example 1, no coupling modification was added in step 1. Compared with Example 3, the dispersibility of inorganic powder and matrix was reduced, the reinforcing and filling properties decreased, and the mechanical properties, aging resistance and antistatic properties were reduced.

[0133] In Comparative Example 2, silicon dioxide was used instead of titanium dioxide in step 1. Compared with Example 3, the mechanical properties of Comparative Example 2 decreased after UV aging. This is because titanium dioxide has good refractive properties and high photoactivity, which can both reflect and scatter ultraviolet rays, as well as absorb ultraviolet rays, thus providing a stronger blocking ability against ultraviolet rays.

[0134] In Comparative Example 3, the toughening and reinforcing effect of EVA was lacking, resulting in a decrease in mechanical properties.

[0135] In Comparative Example 4, the modified powder was missing, and compared with Example 3, the mechanical properties, aging resistance and antistatic properties all decreased to varying degrees.

[0136] Comparative Examples 5, 6, 7, 8, 9, and 10 differed from Example 3 in their preparation process parameters or component ratios of the polymeric antistatic agents, resulting in varying degrees of decrease in overall performance.

[0137] Comparative Example 11 lacked a polymeric antistatic agent, while Comparative Example 12 used an anionic antistatic agent MOA3PK. Compared with Example 3, the resulting polypropylene fibers showed a decrease in antistatic durability, and their antistatic performance was significantly affected by humidity, wiping, and washing.

[0138] Compared to Example 3, Comparative Example 13 lacked a compatibilizer, resulting in decreased interfacial properties between the blend components, reduced blend stability, and decreased mechanical properties.

[0139] Comparative Example 14 lacks lubricant and dispersant compared to Example 3, resulting in decreased mechanical properties.

[0140] Comparative Example 15, with a stretching ratio of 10 times, showed a decrease in fiber mechanical properties.

[0141] Comparative Example 16 did not undergo heat setting, which failed to eliminate the internal stress of the fibers, resulting in decreased fiber dimensional stability and reduced mechanical properties of the product.

[0142] Comparative Example 17 is pure polypropylene fiber, which lacks many modifiers and has poor overall performance.

[0143] The above embodiments and figures are not intended to limit the products and methods of the present invention. Any appropriate changes or modifications made by those skilled in the art should be considered as not departing from the patent scope of the present invention.

Claims

1. A method for preparing long-lasting antistatic polypropylene fiber, characterized in that, Includes the following steps: Step 1, Preparation of modified powder: Inorganic oxides are dispersed in an organic solvent containing a coupling agent, the reaction atmosphere is controlled, the mixture is stirred and subjected to a first temperature-controlled reaction; then the copolymer is added, and a second temperature-controlled reaction is carried out to obtain the modified powder; The inorganic oxide is titanium dioxide; the copolymer is one or a combination of two or more of ethylene-vinyl acetate block copolymer, polyethylene, and polypropylene; the coupling agent is one or a combination of two or more of KH-550, KH560, KR-TTS, KR-38S, 3-methoxypropyltrimethoxysilane, and 3-methoxypropyltriethoxysilane; the organic solvent is one or a combination of two or more of toluene, ethanol, and petroleum ether. The modified powder is grafted modified titanium dioxide; Step 2, Preparation of polymeric antistatic agent: Caprolactam, polyether, deionized water, end-capping agent, water absorbent and catalyst are mixed in a certain proportion and then subjected to melting, esterification and polycondensation reactions in sequence to obtain a polymeric permanent antistatic agent. The polymeric permanent antistatic agent is a polycaprolactam-polyether type permanent antistatic agent. The polyether is polyethylene oxide; the end-capping agent is one or a combination of two or more of adipic acid, sebacic acid, hexanoic acid, and benzoic acid; the water-absorbing agent is concentrated sulfuric acid; the catalyst is one or a combination of two or more of antimony glycolate, antimony trioxide, and antimony acetate. In step 2: the esterification stage includes pre-esterification and post-esterification. In the pre-esterification, after the material melts, caprolactam begins to undergo esterification reaction, with the temperature controlled at 220~270℃ and the time at 0.2~1 h. In the post-esterification, the vacuum degree is controlled at 500~1000 Pa, the temperature is controlled at 210~250℃, and the time at 1~3 h. In step 2: during the polycondensation, the vacuum level is controlled at 100~500 Pa, and the reaction time is 0.5~2h; Step 3, Preparation of conductive masterbatch: The modified powder obtained in Step 1 and the polymeric antistatic agent obtained in Step 2 are vacuum dried; then, polypropylene, antioxidant, compatibilizer, dispersant, lubricant, and the vacuum-dried modified powder and polymeric antistatic agent are mixed evenly in a certain proportion, and then melt-extruded, cooled and granulated to obtain conductive masterbatch. Step 4, Spinning of conductive fibers: The conductive masterbatch obtained in step 3 is melted and then extruded through a spinneret, wound, stretched on a hot plate, and heat-set to obtain conductive fibers. In step 4: the spinning temperature is 150~200℃; the hot plate stretching temperature is 70~150℃, and the stretching ratio is 2~6 times; the heat setting temperature is 70~150℃, and the time is 0.1~1 h.

2. The method for preparing long-lasting antistatic polypropylene fiber according to claim 1, characterized in that, In step 1: the reaction atmosphere is N2 or Ar, the reaction temperature of the first temperature-controlled reaction is 100~130℃, and the reaction time is 1~3h; in the second temperature-controlled reaction stage, the system after the first temperature-controlled reaction is first cooled to 30~60℃, and then the copolymer is added, and the reaction continues for 0.5~2h.

3. The method for preparing long-lasting antistatic polypropylene fiber according to claim 1, characterized in that, In step 2: during the melting process, the atmosphere is controlled to be N2 or Ar, the reaction temperature is controlled to be 200~260℃, and the time is controlled to be 0.2~1 h.

4. The method for preparing long-lasting antistatic polypropylene fiber according to claim 1, characterized in that, In step 3, the antioxidant is one or more of antioxidant 1010, antioxidant 1076, antioxidant 168, antioxidant PEPQ, and antioxidant 626; the compatibilizer is maleic anhydride-grafted polypropylene and / or ethylene vinyl acetate-grafted maleic anhydride; the lubricant is polyethylene wax and / or fatty acid; and the dispersant is one or a combination of two or more of polyacrylamide, polyvinyl alcohol, ethylenediaminetetramethylenephosphonic acid, and hydroxyethylidene diphosphate.

5. The method for preparing long-lasting antistatic polypropylene fiber according to claim 1, characterized in that, In step 3: during melt extrusion, the temperature range of the melt extrusion equipment is 170~260℃, the screw pressure is 0.05~1MPa, the screw speed is 30~120 rpm, and the pelletizing speed is 10~100 rpm; during cooling, water cooling is used.

6. A method for preparing long-lasting antistatic polypropylene fiber according to claim 1 or 4, characterized in that, In step 3, the lubricant is stearic acid.

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