Stain resistant nylon 6 fiber and method of making same

Abstract

This invention relates to the field of nylon fibers, addressing the problems of poor fastness and environmental unfriendliness in the post-processing of stain-resistant fabrics. It provides a stain-resistant nylon 6 fiber and its preparation method, comprising modified nylon chips modified with a monocarboxyl end-capping agent and PA6-PDMS block-modified chips. The preparation method involves adding a monocarboxyl end-capping agent to caprolactam and performing ring-opening polymerization to prepare modified nylon chips; adding a dicarboxyl end-capping agent to caprolactam and performing ring-opening polymerization to prepare a dicarboxyl-terminated PA6 prepolymer, which is then in-situ polymerized with diamino-terminated polydimethylsiloxane and diisocyanate to obtain block-modified chips; mixing the modified nylon chips, block-modified chips, and amino-containing cage-like semisiloxane, melt-extruding, and spinning to obtain stain-resistant nylon 6 fiber. This invention combines the stain-resistant function of modified chips and the hydrophobic properties of PA6-PDMS block-modified chips through chip blending and spinning, resulting in permanently stain-resistant nylon 6 fiber while avoiding the use of fluorides.

Description

Technical Field

[0001] This invention relates to the field of nylon fibers, and in particular to a stain-resistant nylon 6 fiber and its preparation method. Background Technology

[0002] With the rapid development of society and economy and the continuous improvement of people's living standards, the demand for functional fibers is gradually expanding. Nylon 6 fiber, as the second largest civilian-use fiber, is inevitably stained by substances like cola and soy sauce during actual use. Since cola and soy sauce are acidic substances, the fibers are difficult to clean once stained. Currently, stain-resistant fabrics on the market are treated with post-processing, but the stain resistance gradually deteriorates with repeated washing. For example, patent CN102995392B discloses a high-colorfastness, stain-resistant, and easy-to-clean special tie fabric and its preparation method. This fabric uses masterbatch-dyed, micro-cavitated fine denier high-simulation polyester filament as raw material, woven with satin, twill, modified twill, broken twill, or plain weave structures. It is then treated with alkali reduction, acid treatment, and fluorocarbon alcohol auxiliaries with short carbon chains of no more than 8 carbons for stain-resistant and easy-to-clean finishing and setting. However, most of these finishing agents are fluorides, which are not environmentally friendly. Therefore, developing a permanently stain-resistant and environmentally friendly nylon 6 fiber is of great significance. Summary of the Invention

[0003] To overcome the problems of poor fastness and environmental unfriendliness in the post-processing preparation of stain-resistant fabrics, this invention provides a stain-resistant nylon 6 fiber and its preparation method. By combining the stain-resistant function of modified chips and the hydrophobic properties of PA6-PDMS block modified chips through chip blending and spinning, a permanent stain-resistant nylon 6 fiber is obtained, avoiding the use of fluorides.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A stain-resistant nylon 6 fiber, the chips of which are composed of modified nylon chips modified with monocarboxyl end-capping agent and PA6-PDMS block modified chips.

[0006] Preferably, the mass ratio of modified nylon chips to PA6-PDMS block modified chips is (90-95):(5-10).

[0007] The present invention also provides a method for preparing the stain-resistant nylon 6 fiber, comprising the following steps:

[0008] (1) Add a monocarboxyl end-capping agent to caprolactam and prepare modified nylon chips by ring-opening polymerization;

[0009] (2) Add a dicarboxyl end-capping agent to caprolactam and prepare a dicarboxyl-terminated PA6 prepolymer by ring-opening polymerization; the dicarboxyl-terminated PA6 prepolymer and diamino-terminated polydimethylsiloxane and diisocyanate are subjected to in-situ polymerization reaction to obtain PA6-PDMS block modified chips.

[0010] (3) The modified nylon chips obtained in step (1), the PA6-PDMS block modified chips obtained in step (2), and the amino-containing cage semisiloxane are mixed, melt-extruded, and spun to obtain stain-resistant nylon 6 fibers.

[0011] Modified nylon chips are mainly produced by introducing end-capping agents during the nylon polymerization process. By reducing the content of amino groups at the fiber ends, acid dyes become difficult to adhere to, making it difficult for substances like cola and soy sauce to adhere to the nylon fibers, thus exhibiting anti-dyeing properties. Block-modified nylon chips are produced by melt polymerization of low molecular weight PA6 with dicarboxyl groups and polydimethylsiloxane with diamino groups as reactants, using diisocyanate as a chain extender to obtain a PA6-PDMS multiblock copolymer. The Si-CH3 structure in PDMS (polydimethylsiloxane) is hydrophobic; introducing PDMS can improve the hydrophobicity of nylon fibers.

[0012] Preferably, the monocarboxyl end-capping agent in step (1) is benzoic acid, and the mass of benzoic acid is 2 to 5% of the mass of caprolactam.

[0013] Preferably, a catalyst is added in step (1), which is at least one of sodium hydroxide, p-toluenesulfonic acid, phosphoric acid, and sodium hypophosphite, and the mass of the catalyst is 500 to 2000 ppm of the mass of caprolactam.

[0014] Preferably, deionized water is added in step (1), and the mass of the deionized water is 2 to 4% of the mass of caprolactam.

[0015] Preferably, in step (1), the ring-opening temperature is 208-225℃, the pressure is 0.54-0.8MPa, and the ring-opening time is 1-2h; the polymerization temperature is 250-265℃, the pressure is evacuated to 0.03-0.05MPa, and the evacuation time is 0.5-2h.

[0016] Preferably, the dicarboxylic acid end-capping agent in step (2) is adipic acid;

[0017] Preferably, deionized water is added in step (2), and the mass of the deionized water is 2 to 4% of the mass of caprolactam.

[0018] Preferably, in step (2), the ring-opening temperature is 208–225°C, the pressure is 0.5–0.7 MPa, and the ring-opening time is 1–2 h; the polymerization temperature is 250–260°C, the pressure is evacuated to 0.07–0.08 MPa, and the evacuation time is 1–2 h.

[0019] Preferably, in step (2), the number-average molecular weight of the dicarboxyl-terminated PA6 prepolymer is 1000–3000 g / mol, and the number-average molecular weight of the diamino-terminated polydimethylsiloxane is 2000–5000 g / mol; the diisocyanate is at least one of hexamethylene diisocyanate, isophorone diisocyanate, and diphenylmethane diisocyanate; the molar ratio of the dicarboxyl-terminated PA6 prepolymer, the diamino-terminated polydimethylsiloxane, and the diisocyanate is 1:1:(1–2); deionized water is also added during in-situ polymerization, and the mass of deionized water is 20–30% of the total mass of the feed.

[0020] As a preferred embodiment, the in-situ polymerization conditions in step (2) are as follows: after feeding, the mixture is vented through three channels and then heated to 160–180°C, then depressurized to atmospheric pressure for 1.5–2 hours. The mixture is then kept at this temperature for 1–2 hours. Afterward, the temperature is raised to 240–250°C and the polymerization is carried out under vacuum for 1–2 hours.

[0021] Preferably, the amino-containing cage-like semisiloxane in step (3) is one or a combination of two or more of the following: p-aminophenyl isobutyl cage-like semisiloxane, aminoethylaminopropyl isobutyl cage-like semisiloxane, aminopropyl isobutyl cage-like semisiloxane, and N-methylaminopropyl isobutyl cage-like semisiloxane; the mass of the amino-containing cage-like semisiloxane is 0.2 to 1% of the total mass of the slices.

[0022] Preferably, the slices from step (3) are sequentially subjected to vacuum drying, melt extrusion, spinning, side-blowing cooling, drawing, tension heat setting, winding, and winding treatment to obtain stain-resistant nylon 6 fibers. Specific parameters are as follows: vacuum drying temperature is 100-110℃, drying time is 20-24h; melt extrusion conditions are: screw zone 1 temperature of screw extruder is 230-250℃, zone 2 temperature is 240-250℃, and zone 3 temperature is 250-260℃; spinning conditions are: composite spinning box temperature is 250-260℃; number of spinneret holes is 48, side-blowing cooling temperature is 15℃, relative humidity is 80%; winding speed is 3200m / min; drawing ratio is 1.9-3 times, and tension heat setting temperature is 110-130℃.

[0023] Therefore, the beneficial effects of the present invention are as follows: (1) By combining the anti-fouling function of modified chips and the hydrophobic properties of PA6-PDMS block modified chips through chip blending and spinning, a method for preparing permanent stain-resistant nylon 6 fibers is provided, which reduces the application of fluoride materials and promotes the development of environmental protection. (2) The high reactivity of isocyanate groups solves the problem of the large polarity difference between PDMS and PA6 phases, which leads to phase separation and ineffective reaction during polymerization. (3) Compared with direct PDMS masterbatch blending, the compatibility of the two phases is improved by using PA6-PDMS chips and modified nylon chips for blending, avoiding a serious decrease in fiber breaking strength after increasing PMDS content. (4) The amino-containing cage-like semisiloxane can further improve the dispersion uniformity of PDMS in the nylon matrix, and also has a certain hydrophobic effect, which is also beneficial to improving the hydrophobic properties of the fiber. Detailed Implementation

[0024] The technical solution of the present invention will be further described below through specific embodiments.

[0025] In this invention, unless otherwise specified, the raw materials and equipment used are commercially available or commonly used in the art. The methods in the embodiments, unless otherwise specified, are conventional methods in the art. Unless otherwise specified, all parts are parts by weight, temperatures are expressed in °C or at ambient temperature, and pressures are at or near atmospheric pressure. Various variations and combinations of reaction conditions (e.g., component concentrations, required solvents, solvent mixtures, temperature, pressure, and other reaction ranges) and conditions that can be used to optimize the purity and yield of the product obtained by the method exist, and only reasonable routine experiments are needed to optimize such method conditions.

[0026] Example

[0027] A method for preparing stain-resistant nylon 6 fiber includes the following steps:

[0028] I. Preparation of modified nylon slices

[0029] Modified nylon chips were prepared by ring-opening polymerization of a monocarboxyl-termining agent, caprolactam, deionized water, and a catalyst in a reactor. The monocarboxyl-termining agent was benzoic acid, with a mass ratio of 2-5% of the caprolactam mass. The catalyst was selected from at least one of sodium hydroxide, p-toluenesulfonic acid, phosphoric acid, and sodium hypophosphite, with a catalyst mass ratio of 500-2000 ppm of the caprolactam mass. The deionized water mass ratio was 2-4% of the caprolactam mass.

[0030] The conditions for the ring-opening reaction are as follows: temperature 208–225℃, pressure 0.54–0.8 MPa, and ring-opening time under pressure of 1–2 h. The conditions for the polymerization reaction are as follows: temperature 250–265℃, pressure evacuated to 0.03–0.05 MPa, and evacuation time of 0.5–2 h.

[0031] II. Preparation of PA6-PDMS Block Modified Slices

[0032] (1) A dicarboxylated end-capping agent, caprolactam and deionized water were added to a reactor and ring-opened polymerized to prepare a dicarboxylated end-capped PA6 prepolymer.

[0033] The dicarboxylic acid end-capping agent is adipic acid. The mass of the deionized water is 2-4% of the mass of caprolactam.

[0034] The conditions for the ring-opening reaction are as follows: temperature 208–225℃, pressure 0.5–0.7 MPa, and ring-opening time under pressure for 1–2 hours. The conditions for the polymerization reaction are as follows: temperature 250–260℃, pressure evacuated to 0.07–0.08 MPa, and evacuation time for 1–2 hours.

[0035] (2) The dicarboxyl-terminated PA6 prepolymer, diamino-terminated polydimethylsiloxane, deionized water and diisocyanate were added to the reactor for in-situ polymerization to obtain PA6-PDMS block modified chips.

[0036] The number-average molecular weight of the dicarboxyl-terminated PA6 prepolymer is 1000–3000 g / mol. The number-average molecular weight of the diamino-terminated polydimethylsiloxane is 2000–5000 g / mol. The diisocyanate is at least one of hexamethylene diisocyanate, isophorone diisocyanate, and diphenylmethane diisocyanate; the molar ratio of the dicarboxyl-terminated PA6 prepolymer, the diamino-terminated polydimethylsiloxane, and the diisocyanate is 1:1:(1–2). The deionized water accounts for 20%–30% of the total feed mass.

[0037] The reaction conditions for the in-situ polymerization are as follows: after feeding, the mixture is vented through three valves and released three times, heated to 160–180°C, and then depressurized to atmospheric pressure for 1.5–2 hours. The reaction is then maintained at this temperature for 1–2 hours. Afterward, the temperature is raised to 240–250°C, and the polymerization is carried out under vacuum for 1–2 hours.

[0038] III. Preparation of stain-resistant nylon 6 fibers

[0039] The modified nylon chips obtained in step one, the PA6-PDMS block modified chips obtained in step two, and the amino-containing cage-like semisiloxane were mixed, melt-extruded, and spun to obtain stain-resistant nylon 6 fibers.

[0040] The modified nylon chips comprise 90-95% of the total chip mass (modified nylon chips and PA6-PDMS block modified chips), and the PA6-PDMS block modified chips comprise 5-10% of the total chip mass. The amino-containing cage-like semisiloxane is one or a combination of two or more of the following: p-aminophenyl isobutyl cage-like semisiloxane, aminoethylaminopropyl isobutyl cage-like semisiloxane, aminopropyl isobutyl cage-like semisiloxane, and N-methylaminopropyl isobutyl cage-like semisiloxane; the amino-containing cage-like semisiloxane comprises 0.2-1% of the total chip mass.

[0041] The slices undergo vacuum drying, melt extrusion, spinning, side-blowing cooling, drawing, tension heat setting, winding, and winding treatment in sequence. The temperature is 100–110℃, and the drying time is 20–24 hours. The melt extrusion conditions are: screw zone 1 temperature of 230–250℃, zone 2 temperature of 240–250℃, and zone 3 temperature of 250–260℃. The spinning conditions are: composite spinning box temperature of 250–260℃; spinneret with 48 spinneret holes; side-blowing cooling temperature of 15℃; relative humidity of 80%; winding speed of 3200 m / min; draw ratio of 1.9–3 times; and tension heat setting temperature of 110–130℃.

[0042] The present invention also provides a stain-resistant nylon 6 fiber, which is prepared by the above-described method.

[0043] Example 1

[0044] The preparation method of a stain-resistant nylon 6 fiber is as follows:

[0045] (1) Preparation of modified nylon chips: Caprolactam, 2% benzoic acid (by mass), 1500 ppm phosphoric acid, and 3% deionized water were added to a polymerization reactor. After three venting cycles, the temperature was raised to 225℃ and the pressure was maintained at 0.7 MPa for 2 hours to open the ring. After releasing to atmospheric pressure, the temperature was raised to 260℃, and a vacuum was drawn to 0.04 MPa for 2 hours of vacuum polymerization.

[0046] (2) Preparation of dicarboxylate-terminated PA6 prepolymer: Caprolactam and adipic acid were added to a polymerization reactor at a molar ratio of 7.56:1, followed by the addition of deionized water at 4% of the mass of caprolactam. After three venting cycles, the reactor was heated to 220°C and held at 0.7 MPa for 2 hours to initiate ring-opening. After releasing to atmospheric pressure, the reactor was heated to 250°C and evacuated to 0.08 MPa for 2 hours under vacuum.

[0047] (3) Preparation of block-modified chips: 1000 g / mol of dicarboxylated PA6 prepolymer, 3000 g / mol of diamino-terminated polydimethylsiloxane, and hexamethylene diisocyanate were added to a polymerization reactor in a molar ratio of 1:1:1, followed by the addition of deionized water accounting for 20% of the total feed mass. After three venting cycles, the temperature was raised to 180°C, the pressure was released to atmospheric pressure for 2 hours, and the reaction was maintained at this temperature for 1 hour. Then, the temperature was raised to 250°C, and the polymerization reaction was carried out under vacuum for 1 hour.

[0048] (4) Preparation of stain-resistant nylon 6 fiber: Modified nylon chips and block modified chips were placed in a vacuum drum for drying at 100℃ for 24 hours. The dried modified nylon chips and block modified chips were mixed at a mass ratio of 1:9, and then 0.2% of aminopropyl isobutyl cage semisiloxane (aminopropyl isobutyl cage semisiloxane) was added to the total chips (modified nylon chips and PA6-PDMS block modified chips). The uniformly mixed chips were fed into a hopper, melt-extruded through a screw extruder, metered through a melt pipe and metering pump, and then spun through a spinneret, cooled by side blowing, drawn, tensioned and heat-set, wound, and wound to obtain stain-resistant nylon 6 fiber. The screw temperature of the screw extruder was 240℃ in zone one, 250℃ in zone two, and 260℃ in zone three, and the temperature of the composite spinning box was 260℃. The spinneret had 48 spinneret holes. The side-blowing cooling temperature is 15℃, and the relative humidity is 80%. The winding speed is 3200m / min. The draw ratio is 1.9 times, and the tension heat setting temperature is 130℃.

[0049] The obtained stain-resistant nylon 6 fiber has a linear density of 70 dtex.

[0050] Example 2

[0051] The preparation method of a stain-resistant nylon 6 fiber is as follows:

[0052] (1) Preparation of modified nylon chips: 3% benzoic acid, 1500 ppm phosphoric acid, 3% deionized water, and caprolactam were added to the polymerization reactor. After three venting cycles, the temperature was raised to 225℃ and the pressure was maintained at 0.7 MPa for 2 hours for ring opening. After releasing to atmospheric pressure, the temperature was raised to 260℃, and the pressure was evacuated to 0.05 MPa for 2 hours for vacuum polymerization.

[0053] (2) Preparation of dicarboxylate-terminated PA6 prepolymer: Caprolactam and adipic acid were added to the polymerization reactor at a molar ratio of 7.56:1, followed by the addition of 4% deionized water. After three venting cycles, the temperature was raised to 220℃ and the pressure was maintained at 0.7 MPa for 2 hours to initiate ring opening. After releasing to atmospheric pressure, the temperature was raised to 250℃, and a vacuum was applied to 0.08 MPa for 2 hours of vacuum polymerization.

[0054] (3) Preparation of block-modified chips: 1000 g / mol of dicarboxylated terminal PA6 prepolymer, 5000 g / mol of diamino-terminated polydimethylsiloxane, and hexamethylene diisocyanate were added to a polymerization reactor in a molar ratio of 1:1:1, followed by the addition of 20% deionized water. After three venting cycles, the temperature was raised to 180°C, the pressure was released to atmospheric pressure for 2 hours, and the reaction was maintained at this temperature for 1 hour. The temperature was then raised to 250°C, and the polymerization reaction was carried out under vacuum for 1 hour.

[0055] (4) Preparation of stain-resistant nylon 6 fiber: Modified nylon chips and block modified chips were placed in a vacuum drum for drying at 100℃ for 24 hours. The dried modified nylon chips and block modified chips were mixed at a ratio of 1:9, and 0.2% aminopropyl isobutyl cage semisiloxane was added. The uniformly mixed chips were fed into a hopper, melt-extruded through a screw extruder, metered through a melt pipe and metering pump, and then spun through a spinneret, cooled by side air, drawn, tensioned and heat-set, wound, and wound to obtain stain-resistant nylon 6 fiber. The screw extruder had a screw zone temperature of 240℃, a zone temperature of 250℃, a zone temperature of 260℃, and a composite spinning box temperature of 260℃. The spinneret had 48 spinneret holes. The side air cooling temperature was 15℃, and the relative humidity was 80%. The winding speed was 3200 m / min. The draw ratio is 1.9 times, and the heat setting temperature is 130°C.

[0056] The linear density of the obtained stain-resistant nylon 6 fiber is 69 dtex.

[0057] Example 3

[0058] The preparation method of a stain-resistant nylon 6 fiber is as follows:

[0059] (1) Preparation of modified nylon chips: 5% benzoic acid, 2000 ppm phosphoric acid, 3% deionized water, and caprolactam were added to the polymerization reactor. After three venting cycles, the temperature was raised to 225℃ and the pressure was maintained at 0.7 MPa for 2 hours for ring opening. After releasing to atmospheric pressure, the temperature was raised to 260℃, and the pressure was evacuated to 0.05 MPa for 2 hours for vacuum polymerization.

[0060] (2) Preparation of dicarboxylate-terminated PA6 prepolymer: Caprolactam and adipic acid were added to a polymerization reactor at a molar ratio of 16.4:1, followed by the addition of 4% deionized water. After three venting cycles, the reactor was heated to 220°C and held at 0.7 MPa for 2 hours to initiate ring-opening. After releasing to atmospheric pressure, the reactor was heated to 250°C and evacuated to 0.08 MPa for 2 hours under vacuum.

[0061] (3) Preparation of block-modified chips: 2000 g / mol of dicarboxylated PA6 prepolymer, 5000 g / mol of diamino-terminated polydimethylsiloxane, and hexamethylene diisocyanate were added to a polymerization reactor in a molar ratio of 1:1:1, followed by the addition of 20% deionized water. After three venting cycles, the temperature was raised to 180°C, the pressure was released to atmospheric pressure for 2 hours, and the reaction was maintained at this temperature for 1 hour. The temperature was then raised to 240°C, and the polymerization reaction was carried out under vacuum for 1 hour.

[0062] (4) Preparation of stain-resistant nylon 6 fiber: Modified nylon chips and block modified chips were placed in a vacuum drum for drying at 100℃ for 24 hours. The dried modified nylon chips and block modified chips were mixed at a ratio of 1:9, and 0.2% aminopropyl isobutyl cage semisiloxane was added. The uniformly mixed chips were fed into a hopper, melt-extruded through a screw extruder, metered through a melt pipe and metering pump, and then spun through a spinneret, cooled by side air, drawn, tensioned and heat-set, wound, and wound to obtain stain-resistant nylon 6 fiber. The screw extruder had a screw zone temperature of 240℃, a zone temperature of 250℃, a zone temperature of 260℃, and a composite spinning box temperature of 260℃. The spinneret had 48 spinneret holes. The side air cooling temperature was 15℃, and the relative humidity was 80%. The winding speed was 3200 m / min. The draw ratio is 1.9 times, and the heat setting temperature is 130°C.

[0063] The linear density of the obtained stain-resistant nylon 6 fiber is 72 dtex.

[0064] Example 4

[0065] The preparation method of a stain-resistant nylon 6 fiber is as follows:

[0066] (1) Preparation of modified nylon chips: Caprolactam, 2% benzoic acid (by mass), 500 ppm sodium hypophosphite, and 2% deionized water were added to a polymerization reactor. After three venting cycles, the temperature was raised to 208℃ and the pressure was maintained at 0.54 MPa for 2 hours for ring opening. After releasing to atmospheric pressure, the temperature was raised to 250℃, and a vacuum was drawn to 0.03 MPa for 2 hours for vacuum polymerization.

[0067] (2) Preparation of dicarboxylate-terminated PA6 prepolymer: Caprolactam and adipic acid were added to a polymerization reactor at a molar ratio of 7.56:1, followed by the addition of 2% (by mass) of deionized water. After three venting cycles, the reactor was heated to 208°C and held at 0.5 MPa for 1 hour to initiate ring opening. After releasing to atmospheric pressure, the reactor was heated to 250°C and evacuated to 0.07 MPa for 2 hours under vacuum.

[0068] (3) Preparation of block-modified chips: 1000 g / mol of dicarboxylated PA6 prepolymer, 2000 g / mol of diamino-terminated polydimethylsiloxane, and isophorone diisocyanate were added to a polymerization reactor in a molar ratio of 1:1:2, followed by the addition of deionized water accounting for 30% of the total feed mass. After three venting cycles, the temperature was raised to 160℃, the pressure was released to atmospheric pressure for 1.5 h, and the reaction was maintained at this temperature for 1 h. Then the temperature was raised to 250℃, and the polymerization reaction was carried out under vacuum for 1 h.

[0069] (4) Preparation of stain-resistant nylon 6 fiber: Modified nylon chips and block modified chips were placed in a vacuum drum for drying at 110℃ for 24 hours. The dried modified nylon chips and block modified chips were mixed at a mass ratio of 5:95, and then 0.5% of N-methylaminopropyl isobutyl cage semisiloxane (based on the total weight of chips, including modified nylon chips and PA6-PDMS block modified chips) was added. The uniformly mixed chips were fed into a hopper, melt-extruded through a screw extruder, metered through a melt pipe and metering pump, and then spun through a spinneret, cooled by side blowing, drawn, tensioned and heat-set, wound, and wound to obtain stain-resistant nylon 6 fiber. The screw extruder had a screw zone temperature of 250℃, a zone temperature of 260℃, a zone temperature of 260℃, and a composite spinning box temperature of 260℃. The spinneret had 48 spinneret holes. The side-blowing cooling temperature is 15℃, and the relative humidity is 80%. The winding speed is 3200m / min. The draw ratio is 3 times, and the tension heat setting temperature is 110℃.

[0070] The linear density of the obtained stain-resistant nylon 6 fiber is 56 dtex.

[0071] Example 5

[0072] The preparation method of a stain-resistant nylon 6 fiber is as follows:

[0073] (1) Preparation of modified nylon chips: Caprolactam, 2% benzoic acid (by mass), 1500 ppm p-toluenesulfonic acid, and 4% deionized water were added to a polymerization reactor. After three venting cycles, the temperature was raised to 215℃ and the pressure was maintained at 0.8 MPa for 1 hour to open the ring. After releasing to atmospheric pressure, the temperature was raised to 265℃, and a vacuum was drawn to 0.05 MPa for 0.5 hours of vacuum polymerization.

[0074] (2) Preparation of dicarboxylate-terminated PA6 prepolymer: Caprolactam and adipic acid were added to a polymerization reactor at a molar ratio of 25.22:1, followed by the addition of 3% (by mass) of deionized water. After three venting cycles, the reactor was heated to 225°C and held at 0.6 MPa for 2 hours to initiate ring opening. After releasing to atmospheric pressure, the reactor was heated to 260°C and evacuated to 0.08 MPa for 1 hour under vacuum.

[0075] (3) Preparation of block-modified chips: 3000 g / mol of dicarboxylated PA6 prepolymer, 5000 g / mol of diamino-terminated polydimethylsiloxane, and diphenylmethane diisocyanate were added to a polymerization reactor in a molar ratio of 1:1:1.5, followed by the addition of deionized water accounting for 25% of the total feed mass. After three venting cycles, the temperature was raised to 170℃, the pressure was released to atmospheric pressure for 2 hours, and the reaction was maintained at this temperature for 1 hour. Then, the temperature was raised to 245℃, and the polymerization reaction was carried out under vacuum for 1.5 hours.

[0076] (4) Preparation of stain-resistant nylon 6 fiber: Modified nylon chips and block modified chips were placed in a vacuum drum for drying at 105℃ for 24 hours. The dried modified nylon chips and block modified chips were mixed at a mass ratio of 8:92, and then 1% of the total chips (modified nylon chips and PA6-PDMS block modified chips) of p-aminophenyl isobutyl cage semisiloxane was added. The uniformly mixed chips were fed into a hopper, melt-extruded through a screw extruder, metered through a melt pipe and metering pump, and then spun through a spinneret, cooled by side blowing, drawn, tensioned and heat-set, wound, and wound to obtain stain-resistant nylon 6 fiber. The screw extruder had a screw zone temperature of 245℃, a zone temperature of 245℃, a zone temperature of 250℃, and a composite spinning box temperature of 250℃. The spinneret had 48 spinneret holes. The side-blowing cooling temperature is 15℃, and the relative humidity is 80%. The winding speed is 3200m / min. The draw ratio is 2.5 times, and the tension heat setting temperature is 120℃.

[0077] The linear density of the obtained stain-resistant nylon 6 fiber is 64 dtex.

[0078] Comparative Example

[0079] Comparative Example 1

[0080] The difference from Example 1 is that benzoic acid, a monocarboxyl end-capping agent, was not used in step (1). Specifically:

[0081] The preparation method of a nylon 6 fiber is as follows:

[0082] (1) Preparation of nylon chips: Caprolactam and 3% (by mass) of deionized water were added to the polymerization reactor. After three venting cycles, the temperature was raised to 225℃ and the pressure was maintained at 0.7 MPa for 2 hours to open the ring. After releasing to atmospheric pressure, the temperature was raised to 260℃, and the pressure was evacuated to 0.04 MPa for 2 hours to polymerize under vacuum.

[0083] (2) Preparation of dicarboxylate-terminated PA6 prepolymer: Caprolactam and adipic acid were added to a polymerization reactor at a molar ratio of 7.56:1, followed by the addition of deionized water at 4% of the mass of caprolactam. After three venting cycles, the reactor was heated to 220°C and held at 0.7 MPa for 2 hours to initiate ring-opening. After releasing to atmospheric pressure, the reactor was heated to 250°C and evacuated to 0.08 MPa for 2 hours under vacuum.

[0084] (3) Preparation of block-modified chips: 1000 g / mol of dicarboxylated PA6 prepolymer, 3000 g / mol of diamino-terminated polydimethylsiloxane, and hexamethylene diisocyanate were added to a polymerization reactor in a molar ratio of 1:1:1, followed by the addition of deionized water accounting for 20% of the total feed mass. After three venting cycles, the temperature was raised to 180°C, the pressure was released to atmospheric pressure for 2 hours, and the reaction was maintained at this temperature for 1 hour. Then, the temperature was raised to 250°C, and the polymerization reaction was carried out under vacuum for 1 hour.

[0085] (4) Preparation of Nylon 6 Fiber: Nylon chips and block-modified chips were placed in a vacuum drum for drying at 100℃ for 24 hours. The dried modified nylon chips and block-modified chips were mixed at a mass ratio of 1:9, and then 0.2% of aminopropyl isobutyl cage-like semisiloxane (aminopropyl isobutyl cage-like semisiloxane) was added to the total chips (modified nylon chips and PA6-PDMS block-modified chips). The uniformly mixed chips were fed into a hopper, melt-extruded through a screw extruder, metered through a melt pipe and metering pump, and then spun through a spinneret, cooled by side air, drawn, tensioned and heat-set, wound, and wound to obtain Nylon 6 fiber. The screw extruder had a screw zone temperature of 250℃, a zone temperature of 255℃, a zone temperature of 260℃, and a composite spinning box temperature of 260℃. The spinneret had 48 spinneret holes. The side air cooling temperature was 15℃ and the relative humidity was 80%. The winding speed is 3200 m / min. The draw ratio is 2.3 times, and the tension heat setting temperature is 130°C.

[0086] The obtained stain-resistant nylon 6 fiber has a linear density of 70 dtex.

[0087] Comparative Example 2

[0088] The difference from Example 1 is that the amount of benzoic acid, the end-capping agent, in step (1) is 8%, which exceeds the preferred range of 2-5%. Specifically, the preparation of modified nylon chips is as follows: caprolactam, 8% benzoic acid by mass, 1500 ppm phosphoric acid, and 3% deionized water are added to the polymerization reactor. After three venting and three releases, the temperature is raised to 225°C and the pressure is maintained at 0.7 MPa for 2 hours to open the ring. After releasing to atmospheric pressure, the temperature is raised to 260°C, and the vacuum is drawn to 0.04 MPa for 2 hours of vacuum polymerization.

[0089] Because of excessive benzoic acid, the modified chips had too low a viscosity to be spun normally.

[0090] Comparative Example 3

[0091] The difference from Example 1 is that the capping agent in step (1) is terephthalic acid, a dicarboxylic acid capping agent. Specifically:

[0092] The preparation method of a nylon 6 fiber is as follows:

[0093] (1) Preparation of modified nylon chips: Caprolactam, 2% terephthalic acid (by mass), 1500 ppm phosphoric acid, and 3% deionized water were added to a polymerization reactor. After three venting cycles, the temperature was raised to 225℃ and the pressure was maintained at 0.7 MPa for 2 hours to initiate ring opening. After releasing to atmospheric pressure, the temperature was raised to 260℃, and a vacuum was drawn to 0.04 MPa for 2 hours of vacuum polymerization.

[0094] (2) Preparation of dicarboxylate-terminated PA6 prepolymer: Caprolactam and adipic acid were added to a polymerization reactor at a molar ratio of 7.56:1, followed by the addition of deionized water at 4% of the mass of caprolactam. After three venting cycles, the reactor was heated to 220°C and held at 0.7 MPa for 2 hours to initiate ring-opening. After releasing to atmospheric pressure, the reactor was heated to 250°C and evacuated to 0.08 MPa for 2 hours under vacuum.

[0095] (3) Preparation of block-modified chips: 1000 g / mol of dicarboxylated PA6 prepolymer, 3000 g / mol of diamino-terminated polydimethylsiloxane, and hexamethylene diisocyanate were added to a polymerization reactor in a molar ratio of 1:1:1, followed by the addition of deionized water accounting for 20% of the total feed mass. After three venting cycles, the temperature was raised to 180°C, the pressure was released to atmospheric pressure for 2 hours, and the reaction was maintained at this temperature for 1 hour. Then, the temperature was raised to 250°C, and the polymerization reaction was carried out under vacuum for 1 hour.

[0096] (4) Preparation of Nylon 6 fiber: Modified nylon chips and block modified chips were placed in a vacuum drum for drying at 100℃ for 24 hours. The dried modified nylon chips and block modified chips were mixed at a mass ratio of 1:9, and then 0.2% of aminopropyl isobutyl cage semisiloxane (aminopropyl isobutyl cage semisiloxane) was added to the total chips (modified nylon chips and PA6-PDMS block modified chips). The uniformly mixed chips were fed into a hopper, melt-extruded through a screw extruder, metered through a melt pipe and metering pump, and then spun through a spinneret, cooled by side air, drawn, tensioned and heat-set, wound, and wound to obtain nylon 6 fiber. The screw extruder had a screw zone temperature of 240℃, a zone temperature of 250℃, a zone temperature of 260℃, and a composite spinning box temperature of 260℃. The spinneret had 48 spinneret holes. The side air cooling temperature was 15℃ and the relative humidity was 80%. The winding speed is 3200 m / min. The draw ratio is 1.9 times, and the tension heat setting temperature is 130°C.

[0097] The linear density of the obtained nylon 6 fiber is 70 dtex.

[0098] Comparative Example 4

[0099] The difference from Example 1 is that PDMS block-modified chips are not prepared; instead, modified nylon chips are spun directly. Specifically, a nylon 6 fiber is prepared using the following steps:

[0100] (1) Preparation of modified nylon chips: Caprolactam, 2% benzoic acid (by mass), 1500 ppm phosphoric acid, and 3% deionized water were added to a polymerization reactor. After three venting cycles, the temperature was raised to 225℃ and the pressure was maintained at 0.7 MPa for 2 hours to open the ring. After releasing to atmospheric pressure, the temperature was raised to 260℃, and a vacuum was drawn to 0.04 MPa for 2 hours of vacuum polymerization.

[0101] (2) Preparation of Nylon 6 fiber: Modified nylon chips were placed in a vacuum drum for drying at 100℃ for 24 hours. The chips were then fed into a hopper, melt-extruded through a screw extruder, metered through a melt pipe and metering pump, and spun through a spinneret, cooled by side air, drawn, heat-set at tension, wound, and wound to obtain nylon 6 fiber. The screw extruder had a screw zone temperature of 250℃, a zone temperature of 255℃, a zone temperature of 260℃, and a composite spinning box temperature of 260℃. The spinneret had 48 spinneret holes. The side air cooling temperature was 15℃, and the relative humidity was 80%. The winding speed was 3200 m / min. The draw ratio was 2.4 times, and the heat-set temperature was 130℃.

[0102] The linear density of the obtained nylon 6 fiber is 71 dtex.

[0103] Comparative Example 5

[0104] The difference from Example 1 is that the number-average molecular weight of PDMS in step (3) exceeds the preferred range. Specifically:

[0105] The preparation method of a nylon 6 fiber is as follows:

[0106] (1) Preparation of modified nylon chips: Caprolactam, 2% benzoic acid (by mass), 1500 ppm phosphoric acid, and 3% deionized water were added to a polymerization reactor. After three venting cycles, the temperature was raised to 225℃ and the pressure was maintained at 0.7 MPa for 2 hours to open the ring. After releasing to atmospheric pressure, the temperature was raised to 260℃, and a vacuum was drawn to 0.04 MPa for 2 hours of vacuum polymerization.

[0107] (2) Preparation of dicarboxylate-terminated PA6 prepolymer: Caprolactam and adipic acid were added to a polymerization reactor at a molar ratio of 7.56:1, followed by the addition of deionized water at 4% of the mass of caprolactam. After three venting cycles, the reactor was heated to 220°C and held at 0.7 MPa for 2 hours to initiate ring-opening. After releasing to atmospheric pressure, the reactor was heated to 250°C and evacuated to 0.08 MPa for 2 hours under vacuum.

[0108] (3) Preparation of block-modified chips: 1000 g / mol of dicarboxylated PA6 prepolymer, 10000 g / mol of diamino-terminated polydimethylsiloxane, and hexamethylene diisocyanate were added to a polymerization reactor in a molar ratio of 1:1:1, followed by the addition of deionized water accounting for 20% of the total feed mass. After three venting cycles, the temperature was raised to 180°C, the pressure was released to atmospheric pressure for 2 hours, and the reaction was maintained at this temperature for 1 hour. Then, the temperature was raised to 250°C, and the polymerization reaction was carried out under vacuum for 1 hour.

[0109] (4) Preparation of Nylon 6 fiber: Modified nylon chips and block modified chips were placed in a vacuum drum for drying at 100℃ for 24 hours. The dried modified nylon chips and block modified chips were mixed at a mass ratio of 1:9, and then 0.2% of aminopropyl isobutyl cage semisiloxane (aminopropyl isobutyl cage semisiloxane) was added to the total chips (modified nylon chips and PA6-PDMS block modified chips). The uniformly mixed chips were fed into a hopper, melt-extruded through a screw extruder, metered through a melt pipe and metering pump, and then spun through a spinneret, cooled by side air, drawn, tensioned and heat-set, wound, and wound to obtain nylon 6 fiber. The screw extruder had a screw zone temperature of 240℃, a zone temperature of 250℃, a zone temperature of 260℃, and a composite spinning box temperature of 260℃. The spinneret had 48 spinneret holes. The side air cooling temperature was 15℃ and the relative humidity was 80%. The winding speed is 3200 m / min. The draw ratio is 1.9 times, and the tension heat setting temperature is 130°C.

[0110] The linear density of the obtained nylon 6 fiber is 75 dtex.

[0111] Comparative Example 6

[0112] The difference from Example 1 is that step (3) does not use isocyanate groups as chain extenders. Specifically:

[0113] Preparation of block-modified chips: 1000 g / mol of dicarboxylated terminal PA6 prepolymer and 3000 g / mol of diamino-terminated polydimethylsiloxane were added to a polymerization reactor at a molar ratio of 1:1, followed by the addition of deionized water accounting for 20% of the total feed mass. After three venting cycles, the temperature was raised to 180°C, the pressure was released to atmospheric pressure for 2 hours, and the reaction was maintained at that temperature for 1 hour. The temperature was then raised to 250°C, and the polymerization reaction was carried out under vacuum for 1 hour.

[0114] The carboxyl and amino groups have low reactivity, and the block-modified chips have low viscosity and cannot be spun.

[0115] Comparative Example 7

[0116] The difference from Example 1 is that step (4) did not use an amino-containing cage-like semisiloxane. Specifically:

[0117] The preparation method of a nylon 6 fiber is as follows:

[0118] (1) Preparation of modified nylon chips: Caprolactam, 2% benzoic acid (by mass), 1500 ppm phosphoric acid, and 3% deionized water were added to a polymerization reactor. After three venting cycles, the temperature was raised to 225℃ and the pressure was maintained at 0.7 MPa for 2 hours to open the ring. After releasing to atmospheric pressure, the temperature was raised to 260℃, and a vacuum was drawn to 0.04 MPa for 2 hours of vacuum polymerization.

[0119] (2) Preparation of dicarboxylate-terminated PA6 prepolymer: Caprolactam and adipic acid were added to a polymerization reactor at a molar ratio of 7.56:1, followed by the addition of deionized water at 4% of the mass of caprolactam. After three venting cycles, the reactor was heated to 220°C and held at 0.7 MPa for 2 hours to initiate ring-opening. After releasing to atmospheric pressure, the reactor was heated to 250°C and evacuated to 0.08 MPa for 2 hours under vacuum.

[0120] (3) Preparation of block-modified chips: 1000 g / mol of dicarboxylated PA6 prepolymer, 3000 g / mol of diamino-terminated polydimethylsiloxane, and hexamethylene diisocyanate were added to a polymerization reactor in a molar ratio of 1:1:1, followed by the addition of deionized water accounting for 20% of the total feed mass. After three venting cycles, the temperature was raised to 180°C, the pressure was released to atmospheric pressure for 2 hours, and the reaction was maintained at this temperature for 1 hour. Then, the temperature was raised to 250°C, and the polymerization reaction was carried out under vacuum for 1 hour.

[0121] (4) Preparation of Nylon 6 fiber: Modified nylon chips and block modified chips were placed in a vacuum drum for drying at 100℃ for 24 hours. The dried modified nylon chips and block modified chips were mixed at a mass ratio of 1:9. The uniformly mixed chips were fed into a hopper, melt-extruded through a screw extruder, metered through a melt pipe and metering pump, and then spun through a spinneret, cooled by side air, drawn, heat-set at tension, wound, and wound to obtain nylon 6 fiber. The screw extruder had a screw zone temperature of 240℃, a zone temperature of 250℃, a zone temperature of 260℃, and a composite spinning box temperature of 260℃. The spinneret had 48 spinneret holes. The side air cooling temperature was 15℃, and the relative humidity was 80%. The winding speed was 3200 m / min. The draw ratio was 1.9 times, and the heat-set temperature was 130℃.

[0122] The linear density of the obtained nylon 6 fiber is 72 dtex.

[0123] Comparative Example 8

[0124] The difference from Example 1 is that the amount of amino-containing cage-like semisiloxane used in step (4) is 2%, which exceeds the preferred range of 0.2-1%. Specifically:

[0125] The preparation method of a nylon 6 fiber is as follows:

[0126] (1) Preparation of modified nylon chips: Caprolactam, 2% benzoic acid (by mass), 1500 ppm phosphoric acid, and 3% deionized water were added to a polymerization reactor. After three venting cycles, the temperature was raised to 225℃ and the pressure was maintained at 0.7 MPa for 2 hours to open the ring. After releasing to atmospheric pressure, the temperature was raised to 260℃, and a vacuum was drawn to 0.04 MPa for 2 hours of vacuum polymerization.

[0127] (2) Preparation of dicarboxylate-terminated PA6 prepolymer: Caprolactam and adipic acid were added to a polymerization reactor at a molar ratio of 7.56:1, followed by the addition of deionized water at 4% of the mass of caprolactam. After three venting cycles, the reactor was heated to 220°C and held at 0.7 MPa for 2 hours to initiate ring-opening. After releasing to atmospheric pressure, the reactor was heated to 250°C and evacuated to 0.08 MPa for 2 hours under vacuum.

[0128] (3) Preparation of block-modified chips: 1000 g / mol of dicarboxylated PA6 prepolymer, 3000 g / mol of diamino-terminated polydimethylsiloxane, and hexamethylene diisocyanate were added to a polymerization reactor in a molar ratio of 1:1:1, followed by the addition of deionized water accounting for 20% of the total feed mass. After three venting cycles, the temperature was raised to 180°C, the pressure was released to atmospheric pressure for 2 hours, and the reaction was maintained at this temperature for 1 hour. Then, the temperature was raised to 250°C, and the polymerization reaction was carried out under vacuum for 1 hour.

[0129] (4) Preparation of Nylon 6 fiber: Modified nylon chips and block modified chips were placed in a vacuum drum for drying at 100℃ for 24 hours. The dried modified nylon chips and block modified chips were mixed at a mass ratio of 1:9, and 2% aminopropyl isobutyl cage semisiloxane was added by mass of the total chips (modified nylon chips and PA6-PDMS block modified chips). The uniformly mixed chips were fed into a hopper, melt-extruded by a screw extruder, metered by a melt pipe and metering pump, and then spun by a spinneret, cooled by side air, drawn, tensioned and heat-set, wound, and wound to obtain nylon 6 fiber. The screw extruder had a screw zone temperature of 240℃, a zone temperature of 250℃, a zone temperature of 260℃, and a composite spinning box temperature of 260℃. The spinneret had 48 spinneret holes. The side air cooling temperature was 15℃ and the relative humidity was 80%. The winding speed is 3200 m / min. The draw ratio is 1.9 times, and the tension heat setting temperature is 130°C.

[0130] The linear density of the obtained nylon 6 fiber is 70 dtex.

[0131] Comparative Example 9

[0132] The difference from Example 1 is that in step (3), the amino-containing cage-like semisiloxane is replaced with 3-aminopropyltrimethoxysilane. Specifically:

[0133] The preparation method of a nylon 6 fiber is as follows:

[0134] (1) Preparation of modified nylon chips: Caprolactam, 2% benzoic acid (by mass), 1500 ppm phosphoric acid, and 3% deionized water were added to a polymerization reactor. After three venting cycles, the temperature was raised to 225℃ and the pressure was maintained at 0.7 MPa for 2 hours to open the ring. After releasing to atmospheric pressure, the temperature was raised to 260℃, and a vacuum was drawn to 0.04 MPa for 2 hours of vacuum polymerization.

[0135] (2) Preparation of dicarboxylate-terminated PA6 prepolymer: Caprolactam and adipic acid were added to a polymerization reactor at a molar ratio of 7.56:1, followed by the addition of deionized water at 4% of the mass of caprolactam. After three venting cycles, the reactor was heated to 220°C and held at 0.7 MPa for 2 hours to initiate ring-opening. After releasing to atmospheric pressure, the reactor was heated to 250°C and evacuated to 0.08 MPa for 2 hours under vacuum.

[0136] (3) Preparation of block-modified chips: 1000 g / mol of dicarboxylated PA6 prepolymer, 3000 g / mol of diamino-terminated polydimethylsiloxane, and hexamethylene diisocyanate were added to a polymerization reactor in a molar ratio of 1:1:1, followed by the addition of deionized water accounting for 20% of the total feed mass. After three venting cycles, the temperature was raised to 180°C, the pressure was released to atmospheric pressure for 2 hours, and the reaction was maintained at this temperature for 1 hour. Then, the temperature was raised to 250°C, and the polymerization reaction was carried out under vacuum for 1 hour.

[0137] (4) Preparation of Nylon 6 fiber: Modified nylon chips and block modified chips were placed in a vacuum drum for drying at 100℃ for 24 hours. The dried modified nylon chips and block modified chips were mixed at a mass ratio of 1:9, and 0.2% of the total chips (modified nylon chips and PA6-PDMS block modified chips) of 3-aminopropyltrimethoxysilane was added. The uniformly mixed chips were fed into a hopper, melt-extruded through a screw extruder, metered through a melt pipe and metering pump, and then spun through a spinneret, cooled by side air, drawn, tensioned and heat-set, wound, and wound to obtain nylon 6 fiber. The screw extruder had a screw zone temperature of 240℃, a zone temperature of 250℃, a zone temperature of 260℃, and a composite spinning box temperature of 260℃. The spinneret had 48 spinneret holes. The side air cooling temperature was 15℃ and the relative humidity was 80%. The winding speed is 3200 m / min. The draw ratio is 1.9 times, and the tension heat setting temperature is 130°C.

[0138] The linear density of the obtained nylon 6 fiber is 70 dtex.

[0139] Performance testing

[0140] The performance of the stain-resistant nylon 6 fibers prepared in each embodiment and comparative example was tested using the following methods: The hydrophobicity of the stain-resistant nylon 6 fibers was measured using the angle measurement method with a DSA10-MK2 contact angle meter, according to GB / T30693-2014 "Measurement of the contact angle between plastic films and water". The staining grade of the stain-resistant nylon 6 fibers was tested according to GB / T30159.1-2013 "Textiles - Testing and evaluation of stain resistance - Part 1: Stain resistance". The permanent stain resistance was tested by evaluating the staining grade after 50 washes. The results are shown in Table 1.

[0141] Table 1. Strength and stain resistance of composite fibers in Examples 1-4 and Comparative Examples 1-4

[0142]

[0143] Based on the data from the examples, the fibers of the present invention exhibit good hydrophobicity and stain resistance. With increasing PDMS content and benzoic acid addition, both the water contact angle and staining level improve. Compared to existing technologies, the advantages of the present invention are twofold: firstly, by utilizing a chip blending method, the fibers acquire permanent and excellent hydrophobic and stain-resistant properties; secondly, by using P6-PDMS chips and amino-containing cage-like semisiloxanes, the significant loss of fiber strength or even difficulty in spinning due to increased PDMS content is avoided.

[0144] Compared to Example 1, Comparative Example 1 did not use a monocarboxyl end-capping agent to reduce the end-amino content of the chips, resulting in a decrease in the fiber's stain resistance. Comparative Example 2 used excessive benzoic acid, leading to excessively low viscosity of the modified chips, preventing normal spinning. Comparative Example 3 was not within the preferred range because the dicarboxyl end-capping agent could not effectively reduce the end-amino content of the chips, resulting in poorer stain resistance. Comparative Example 4 did not use PDMS-modified block chips, resulting in non-hydrophobic fibers and decreased stain resistance. Comparative Example 5 used diamino-terminated PDMS with an excessively high number-average molecular weight, resulting in poor dispersion and a significantly lower-than-expected silicon content in the block-modified chips, lower chip viscosity, and no significant improvement in fiber hydrophobicity. Comparative Example 6 had low reactivity between carboxyl and amino groups, resulting in low viscosity of the block-modified chips, preventing spinning. Comparative Example 7 did not use an amino-containing cage-like semisiloxane, leading to poor mixing of the modified and block-modified chips, a significant decrease in fiber breaking strength, and poorer hydrophobicity. In Comparative Example 8, the excessive use of amino-containing cage-like semisiloxanes led to increased costs, but the improvement in hydrophobicity was not significant. In Comparative Example 9, the polyhedral cage-like structure of amino-containing cage-like semisiloxanes exhibited certain hydrophobic properties, but the hydrophobicity of the fibers decreased after being replaced with 3-aminopropyltrimethoxysilane.

[0145] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A process for the production of a stain resistant nylon 6 fiber, characterized by, The method comprises the following steps: (1) adding a monocarboxyl-terminated agent into caprolactam to prepare modified nylon chips through ring-opening polymerization; (2) adding a dicarboxyl-terminated agent into caprolactam to prepare dicarboxyl-terminated PA6 prepolymers through ring-opening polymerization; the dicarboxyl-terminated PA6 prepolymers, diamino-terminated polydimethylsiloxane and diisocyanate are subjected to in-situ polymerization to obtain PA6-PDMS block-modified chips; (3) mixing the modified nylon chips, the PA6-PDMS block-modified chips and amino-containing cage-like silsesquioxane, melt-extruding and spinning to obtain stain-resistant nylon 6 fibers.

2. The production method according to claim 1, characterized by, The mass ratio of the modified nylon chips to the PA6-PDMS block-modified chips is (90-95):(5-10).

3. The production method according to claim 1, characterized by, The monocarboxyl-terminated agent is benzoic acid, and the mass of the benzoic acid is 2-5% of the mass of the caprolactam.

4. The production method according to claim 1, characterized by, The ring-opening polymerization conditions of step (1) include: a ring-opening temperature of 208-225 ℃, a pressure of 0.54-0.8 MPa, a pressure-maintaining ring-opening time of 1-2 h, a polymerization temperature of 250-265 ℃, a pressure of vacuum extraction to 0.03-0.05 MPa, and a vacuum extraction time of 0.5-2 h.

5. The preparation method according to claim 1, characterized in that, The dicarboxyl-terminated agent is adipic acid.

6. The production method according to claim 1, characterized by, The ring-opening polymerization conditions of step (2) include: a ring-opening temperature of 208-225 ℃, a pressure of 0.5-0.7 MPa, a pressure-maintaining ring-opening time of 1-2 h, a polymerization temperature of 250-260 ℃, a pressure of vacuum extraction to 0.07-0.08 MPa, and a vacuum extraction time of 1-2 h.

7. The preparation method according to claim 1, wherein The number-average molecular weight of the dicarboxyl-terminated PA6 prepolymers is 1000-3000 g / mol; The number-average molecular weight of the diamino-terminated polydimethylsiloxane is 2000-5000 g / mol; The diisocyanate is at least one of hexamethylene diisocyanate, isophorone diisocyanate and diphenylmethane diisocyanate; The molar ratio of the dicarboxyl-terminated PA6 prepolymers, the diamino-terminated polydimethylsiloxane and the diisocyanate is 1:1:(1-2).

8. The method of claim 1, wherein, The amino-containing cage-like silsesquioxane is one or a combination of two or more of p-aminophenyl isobutyl cage-like silsesquioxane, aminoethyl aminopropyl isobutyl cage-like silsesquioxane, aminopropyl isobutyl cage-like silsesquioxane and N-methyl aminopropyl isobutyl cage-like silsesquioxane; and the mass of the amino-containing cage-like silsesquioxane is 0.2-1% of the total mass of the chips.

9. The method of claim 1, wherein, Step (3) further comprises vacuum drying, side-blowing air cooling, drafting, tight heat setting, winding and bobbin processing.

Images