Flame-retardant polyester fiber and preparation method thereof

Abstract

The application belongs to the field of polyester fibers, and particularly relates to a flame-retardant polyester fabric, and a preparation method thereof, which comprises the following steps: uniformly mixing 80-100 parts of PET polyester chips, 5-15 parts of ionic liquid modified magnesium hydroxide and 1-5 parts of an antioxidant, and then performing blending extrusion through a double-screw extruder, drawing and cutting to obtain flame-retardant modified polyester masterbatch; then uniformly mixing 70-90 parts of PET polyester chips and 10-30 parts of the flame-retardant modified polyester masterbatch, and performing melt spinning on a double-screw high-speed composite spinning machine to obtain flame-retardant polyester fibers. The prepared polyester fibers have excellent flame-retardant performance and mechanical properties.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of polyester fibers, and particularly relates to a flame-retardant polyester fiber and a preparation method thereof. BACKGROUND

[0002] Polyethylene terephthalate (PET, polyester fiber) is a high polymer polymer that was early industrialized and widely used. It is widely used in fields such as clothing, home textiles, decoration, and industry due to its excellent mechanical properties, dimensional stability, heat resistance, and low cost. It is the largest, fastest-growing, and most widely used synthetic fiber material. Polyethylene terephthalate (PET) is a saturated polyester resin material composed of carbon, hydrogen, and oxygen elements. Currently, terephthalic acid (PTA) and ethylene glycol (EG) are first esterified to produce bis-hydroxyethyl terephthalate (BHET), and then BHET is subjected to a polycondensation reaction under high temperature and high vacuum conditions to obtain the product.

[0003] Since polyester fibers only contain carbon, hydrogen, and oxygen structures, they do not contain phosphorus, nitrogen, or other flame-retardant groups in their molecular structure, and they do not have highly heterocyclic flame-retardant structures. Therefore, polyester is a flammable material. In addition, the semi-crystalline nature of polyester itself results in poor flame retardancy and easy melting characteristics. Therefore, polyester fibers are inherently non-flame-retardant polymers. When heated, they produce a large amount of flammable volatile components, which can easily catch fire and cause fires. The molten droplets produced during combustion can cause secondary combustion, posing a significant threat to people's property safety and lives. This limits the widespread use of polyester fibers in high-flame-retardant-grade fields.

[0004] Magnesium hydroxide, as an inorganic flame retardant, has strong adsorption capacity, thermodynamic stability, no toxicity, no halogen, high humidity and low heat release, low corrosion, good smoke suppression effect, and low cost. It is superior to traditional flame retardants in terms of thermal chemical reaction, suitable polymer, cracking temperature, smoke suppression effect, flame retardant performance, sensitivity to acid, and toxicity. However, when used as a flame retardant in textiles, magnesium hydroxide is often added as an additive to high polymer composites, and only when the amount of magnesium hydroxide is large can the desired flame-retardant effect be achieved. In addition, the poor hydrophilicity and strong polarity of magnesium hydroxide result in poor compatibility with non-polar high polymer materials, easy dispersion, and a certain degree of reduction in the physical and mechanical properties and processing performance of the material, resulting in poor flame-retardant effect. Therefore, it is a research hotspot to develop polyester fibers that balance flame-retardant performance and mechanical properties. SUMMARY

[0005] The purpose of the present application is to provide a flame-retardant polyester fiber with excellent flame-retardant performance and good mechanical properties, and a preparation method thereof. The present application is achieved by the following technical scheme:

[0006] A preparation method of flame-retardant polyester fiber, comprising the following steps:

[0007] Step 1: preparation of ionic liquid modified magnesium hydroxide

[0008] The ionic liquid modifier X, magnesium hydroxide powder and deionized water are added into a reactor, ultrasonic treatment is performed, the obtained suspension is suction filtered, and the filter residue is vacuum dried to obtain ionic liquid modified magnesium hydroxide;

[0009] The structural formula of the ionic liquid modifier X is:

[0010] Step 2: preparation of flame-retardant modified polyester masterbatch

[0011] 80-100 parts of PET polyester chips, 5-15 parts of the ionic liquid modified magnesium hydroxide obtained in step 1 and 1-5 parts of an antioxidant are uniformly mixed by weight parts, and then blended and extruded through a double screw extruder, and then drawn and cut to obtain a flame-retardant modified polyester masterbatch.

[0012] Step 3: preparation of flame-retardant polyester fiber

[0013] 70-90 parts of PET polyester chips and 10-30 parts of the flame-retardant modified polyester masterbatch obtained in step 2 are uniformly mixed by weight parts, and then melt spinning is performed on a double screw high-speed composite spinning machine to obtain flame-retardant polyester fiber.

[0014] In some embodiments, in step 1, the mass ratio of the ionic liquid modifier X to the magnesium hydroxide powder is (0.05-0.15):1.

[0015] In some embodiments, in step 1, the ultrasonic treatment is performed at a temperature of 40-70°C for 0.5-1h.

[0016] In some embodiments, in step 2, the antioxidant is selected from one or more of antioxidant HP-136, antioxidant 1010, antioxidant 168, antioxidant 1076 and antioxidant 1068.

[0017] In some embodiments, in step 2, the rotating speed of the extruder is 100-200 r / min, the temperature of the first zone of the extruder is 250-270°C, the temperature of the second zone is 280-300°C, the temperature of the third zone is 270-290°C, and the temperature of the fourth zone is 260-280°C.

[0018] In some embodiments, in step 3, the spinning temperature of the spinning machine is 260-280°C, the rotating speed of the screw is 400-800 r / min, and the winding speed is 900-1200 r / min.

[0019] In some embodiments, the method for preparing the ionic liquid modifier X comprises the following steps:

[0020] Compound I, compound II and an organic solvent are added into a reactor, and the reaction is stirred at 50-80°C for 1-10 hours. After the reaction, the solid is dissolved in methanol, and then white solid is precipitated by adding acetone. The solid is filtered, washed with acetone, and dried in a vacuum oven to obtain the ionic liquid modifier X. The reaction formula is as follows:

[0021]

[0022] The present application has the following beneficial effects:

[0023] 1) The polyester fiber prepared by the present application has excellent flame retardant performance and mechanical properties. The limiting oxygen index can be as high as 39.5% even with a low amount of magnesium hydroxide added;

[0024] 2) The carboxyl group in the ionic liquid modifier X in the present application can interact with the hydroxyl group on the surface of magnesium hydroxide in the form of a chemical bond, and the imidazole ring can be adsorbed onto the surface of magnesium hydroxide due to its strong polarity, thereby improving the dispersibility of magnesium hydroxide in PET polyester. In addition, the ionic liquid modifier X contains N, Cl and other flame-retardant elements, and the magnesium hydroxide modified by the ionic liquid modifier X can form a dense carbon layer on the surface of the polyester, which can prevent the combustion reaction from further penetrating into the material, thereby achieving greater flame-retardant effect.

[0025] 3) The alkyl chain on the imidazole of the ionic liquid modifier X can be immersed in the PET polyester through physical entanglement and van der Waals interaction, improving the compatibility between magnesium hydroxide and the polymer, thereby improving the mechanical properties. DETAILED DESCRIPTION

[0026] The technical solutions of the present application will be described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0027] The endpoints of the ranges and any values described herein are not limited to the precise values stated. The ranges and values should be construed to include values approximately around the range or value. For ranges, the endpoints are included within the ranges, and the ranges are inclusive of the individual points within the range. The endpoints of the ranges and the individual points can be combined with one or more other endpoints or points to form new ranges, which are also within the scope of the present application.

[0028] The source of the raw materials used in the present application is not limited, and if not otherwise specified, the raw materials used in the present application are all commercially available in the technical field.

[0029] Preparation of ion liquid modifier X

[0030]

[0031] Compound I (0.1 mol), compound II (0.22 mol) and THF (150 mL) were added to a reactor, and the reaction was stirred at 60°C for 5 h. After the reaction, it was cooled to 10°C, and then the precipitated solid was dissolved in methanol (50 ml), followed by adding acetone (200 mL) to precipitate white solid, which was filtered, the filter residue was washed with acetone (3 x 100 mL), and dried in a vacuum oven to obtain ion liquid modifier X, with a yield of 85.9%.

[0032] 1 H-NMR (400 MHz, DMSO-d6): δ (ppm): 11.92 (s, 1H), 9.50 (t, 2H), 7.98 (t, 2H), 7.85 (t, 2H), 7.15 (s, 1H), 4.25 (t, 4H), 1.85-1.73 (m, 4H), 1.31-1.26 (m, 4H), 0.91 (t, 6H).

[0033] Example 1

[0034] A preparation process of a flame-retardant polyester fiber, comprising the following steps:

[0035] Step 1: Preparation of ion liquid modified magnesium hydroxide

[0036] Ion liquid modifier X (10.0 g) obtained in Preparation Example 1, magnesium hydroxide powder (100.0 g) and deionized water (100 mL) were added to a flask, and ultrasonic treatment was carried out at 50°C for 0.5 h, and then the obtained suspension was suction filtered, and the filter residue was dried at 80°C for 5 h to obtain ion liquid modified magnesium hydroxide.

[0037] Step 2: Preparation of flame-retardant modified polyester masterbatch

[0038] 100 parts of PET polyester chips (trade name Wanke WK-821), 5 parts of ion liquid modified magnesium hydroxide obtained in step 1 and 2 parts of antioxidant 1010 were mixed uniformly, and then blended and extruded through a double screw extruder, the rotation speed of the extruder was 100 r / min, the temperature of the first zone of the extruder was 260°C, the temperature of the second zone was 290°C, the temperature of the third zone was 280°C, and the temperature of the fourth zone was 270°C, and then the draw was cut into particles to obtain flame-retardant modified polyester masterbatch.

[0039] Step 3: Preparation of flame-retardant polyester fiber

[0040] The flame-retardant polyester fiber was prepared by melt spinning on a double-screw high-speed composite spinning machine, with 80 parts of PET polyester chips (brand WK-821) and 20 parts of the flame-retardant modified polyester masterbatch obtained in step 2 being uniformly mixed, the spinning temperature being 280°C, the screw rotation speed being 500 r / min, and the winding speed being 1000 r / min.

[0041] Example 2

[0042] A preparation process of a flame-retardant polyester fiber, comprising the following steps:

[0043] Step 1: Preparation of ionic liquid modified magnesium hydroxide

[0044] The ionic liquid modifier X (5.0 g) obtained in Preparation Example 1, magnesium hydroxide powder (100.0 g), and deionized water (100 mL) were added to a flask, ultrasonic treatment was performed at 50°C for 0.5 h, then the obtained suspension was suction filtered, and the filter residue was vacuum dried at 80°C for 5 h to obtain ionic liquid modified magnesium hydroxide.

[0045] Step 2: Preparation of flame-retardant modified polyester masterbatch

[0046] The flame-retardant modified polyester masterbatch was prepared by blending and extruding through a double-screw extruder, with 100 parts of PET polyester chips (brand WK-821), 8 parts of the ionic liquid modified magnesium hydroxide obtained in step 1, and 3 parts of antioxidant 1076 being uniformly mixed, the rotation speed of the extruder being 100 r / min, the temperature of the first zone of the extruder being 260°C, the temperature of the second zone being 290°C, the temperature of the third zone being 280°C, and the temperature of the fourth zone being 270°C, and then the strands were cut to obtain the flame-retardant modified polyester masterbatch.

[0047] Step 3: Preparation of flame-retardant polyester fiber

[0048] The flame-retardant polyester fiber was prepared by melt spinning on a double-screw high-speed composite spinning machine, with 75 parts of PET polyester chips (brand WK-821) and 25 parts of the flame-retardant modified polyester masterbatch obtained in step 2 being uniformly mixed, the spinning temperature being 280°C, the screw rotation speed being 500 r / min, and the winding speed being 1000 r / min.

[0049] Comparative Example 1

[0050] On the basis of Example 1, the ionic liquid modifier X was replaced by stearic acid, and other operation methods and parameters were the same as those in Example 1. The specific operation was as follows:

[0051] Step 1: Preparation of stearic acid modified magnesium hydroxide

[0052] Stearic acid (10.0 g), magnesium hydroxide powder (100.0 g) and deionized water (100 mL) were added into a flask, ultrasonic treatment at 50℃ for 0.5h, then the obtained suspension was suction filtered, and the filter residue was dried at 80℃ under vacuum for 5h to obtain stearic acid modified magnesium hydroxide.

[0053] Step 2: Preparation of flame-retardant modified polyester masterbatch

[0054] According to parts by weight, 100 parts of PET polyester chips (brand WK-821), 5 parts of stearic acid modified magnesium hydroxide obtained in step 1, 2 parts of antioxidant 1010 were uniformly mixed, and then blended and extruded through a double screw extruder, the rotation speed of the extruder was 100r / min, the temperature of the extruder zone 1 was 260℃, the temperature of the extruder zone 2 was 290℃, the temperature of the extruder zone 3 was 280℃, and the temperature of the extruder zone 4 was 270℃, then the strands were cut to obtain flame-retardant modified polyester masterbatch.

[0055] Step 3: Preparation of flame-retardant polyester fiber

[0056] According to parts by weight, 80 parts of PET polyester chips (brand WK-821), 20 parts of flame-retardant modified polyester masterbatch obtained in step 2 were uniformly mixed, and then melt spinning was carried out on a double screw high-speed composite spinning machine, the spinning temperature was 280℃, the screw rotation speed was 500r / min, and the winding speed was 1000r / min to obtain flame-retardant polyester fiber.

[0057] Comparative Example 2

[0058] On the basis of Example 1, the ionic liquid modifier X was replaced by Other operation methods and parameters were the same as those in Example 1, and the corresponding flame-retardant polyester fiber was prepared.

[0059] Performance test

[0060] The flame-retardant properties and mechanical properties of the polyester fibers obtained in Examples 1-2 and Comparative Examples 1-2 were tested, and the test methods were as follows:

[0061] Flame-retardant property: The limiting oxygen index of the polyester fabric was detected according to GB / T 5454-1997 "Textile Burning Property Test Oxygen Index Method".

[0062] Mechanical property: The mechanical property was detected according to GB / T 14344-2022 "Chemical Fiber Filament Tensile Property Test Method", and the specific test conditions were as follows: the pre-tension value was set to 5cN, the clamping length was set to 250mm, the tensile rate was set to 250mm / min, each group of fiber samples was tested for 10-20 times until stable data was obtained, and the CV value was required to be within 15%.

[0063] The results are shown in Table 1.

[0064] Table 1 Performance Test Results

[0065]

[0066] As shown in Table 1, the polyester fibers prepared by this invention exhibit excellent flame retardant and mechanical properties. The improvement in these properties is mainly due to the modification of magnesium hydroxide with an ionic liquid modifier X. The primary reason for this modification is likely that, firstly, flame-retardant magnesium hydroxide powder is difficult to disperse uniformly in hydrophobic PET polyester, while the ionic liquid modifier X used in this invention... The carboxyl groups in the ionic liquid can interact with the hydroxyl groups on the surface of magnesium hydroxide through chemical bonds, and the imidazole rings, due to their strong polarity, can be adsorbed onto the magnesium hydroxide surface, thereby improving the dispersibility of magnesium hydroxide in PET polyester. Furthermore, the ionic liquid modifier X contains flame-retardant elements such as N and Cl, and the magnesium hydroxide modified by ionic liquid modifier X can form a dense carbon layer on the polyester surface. This dense carbon layer can prevent the combustion reaction from further penetrating into the material, thus exerting a greater flame-retardant effect. On the other hand, the alkyl chains on the imidazole ring can penetrate into the PET polyester through physical entanglement and van der Waals interactions, improving the compatibility between magnesium hydroxide and the polymer, thereby enhancing mechanical properties.

[0067] The above embodiments are merely illustrative examples and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing flame-retardant polyester fiber, comprising the following steps: Step 1: Preparation of ionic liquid modified magnesium hydroxide Ionic liquid modifier X, magnesium hydroxide powder and deionized water are added to a reactor and ultrasonically treated. The resulting suspension is filtered, and the filter residue is vacuum dried to obtain ionic liquid modified magnesium hydroxide. The structural formula of the ionic liquid modifier X is: Step 2: Preparation of flame-retardant modified polyester masterbatch By weight, 80-100 parts of PET polyester chips, 5-15 parts of ionic liquid modified magnesium hydroxide obtained in step 1, and 1-5 parts of antioxidant are mixed evenly, and then co-extruded and pelletized through a twin-screw extruder to obtain flame-retardant modified polyester masterbatch. Step 3: Preparation of flame-retardant polyester fibers By weight, 70-90 parts of PET polyester chips and 10-30 parts of flame-retardant modified polyester masterbatch obtained in step 2 are mixed evenly, and then melt-spun on a twin-screw high-speed composite spinning machine to obtain flame-retardant polyester fiber.

2. The preparation method according to claim 1, characterized in that, In step 1, the mass ratio of ionic liquid modifier X to magnesium hydroxide powder is (0.05~0.15):

1.

3. The preparation method according to claim 1, characterized in that, In step 1, the ultrasonic treatment temperature is 40–70℃ and the time is 0.5–1h.

4. The preparation method according to claim 1, characterized in that, In step 2, the antioxidant is selected from one or more of antioxidants HP-136, antioxidant 1010, antioxidant 168, antioxidant 1076, and antioxidant 1068.

5. The preparation method according to claim 1, characterized in that, In step 2, the extruder speed is 100-200 r / min, the temperature of zone 1 of the extruder is 250-270℃, the temperature of zone 2 is 280-300℃, the temperature of zone 3 is 270-290℃, and the temperature of zone 4 is 260-280℃.

6. The preparation method according to claim 1, characterized in that, In step 3, the spinning temperature of the spinning machine is 260-280℃, the screw speed is 400-800 r / min, and the winding speed is 900-1200 r / min.

7. The preparation method according to claim 1, characterized in that, The preparation method of the ionic liquid modifier X includes the following steps: Compound I, compound II, and an organic solvent were added to a reactor, and the mixture was heated to 50–80 °C and stirred for 1–10 h. After the reaction was complete, the mixture was cooled, and the precipitated solid was dissolved in methanol. Acetone was then added to precipitate a white solid, which was filtered. The residue was washed with acetone and dried in a vacuum oven to obtain ionic liquid modifier X. The reaction formula is as follows:

8. Flame-retardant polyester fibers prepared by the method according to any one of claims 1-7.

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