Flame-retardant polyester yarn and preparation method thereof

Abstract

The invention relates to the technical field of yarn, in particular to polyester flame-retardant yarn and a preparation method thereof.The yarn is made of modified polyester fiber containing a microencapsulated flame-retardant additive, the microencapsulated flame-retardant additive is a phosphorus-nitrogen composite flame retardant, and the microencapsulated flame-retardant additive is specifically formed by mixing triethyl phosphate and melamine according to the accurate proportion of 2.2: 1; the polyester flame-retardant yarn and the preparation method thereof have the beneficial effects that the dispersibility and the stability of the flame retardant in the polyester fiber are improved through microencapsulation treatment of the flame-retardant additive, so that the lasting flame-retardant effect of the yarn is ensured.

Description

Technical Field

[0001] The invention relates to the field of yarns, in particular to a polyester flame-retardant yarn and a preparation method thereof. Background Art

[0002] Polyester, as a widely used synthetic fiber, is favored for its excellent physical and mechanical properties, appearance and post-processing performance. However, the flammability of polyester limits its application in certain fields, especially in environments with strict requirements on flame retardancy. In order to improve the flame retardant properties of polyester, researchers have developed a variety of flame retardant modification methods, including copolymerization flame retardant modification, blending flame retardant modification and flame retardant finishing.

[0003] Copolymer flame retardant modification is to add flame retardant monomers during the polymerization process of polyester to obtain a copolymer with flame retardant properties. The flame retardant polyester fiber obtained by this method has long-lasting flame retardant properties, but the process is complicated and the cost is high. Blended flame retardant modification is to add flame retardants to the spinning melt and obtain flame retardant fibers by melt spinning. This method is relatively simple, but the dispersion and stability of the flame retardant have a great influence on the flame retardant properties of the fiber. Flame retardant finishing is to apply flame retardants to the surface of fibers or fabrics, and make the flame retardants firmly attached to the fibers or fabrics by chemical bonding or physical adsorption. This method is simple in process and easy to operate, but the flame retardant durability is relatively poor.

[0004] In recent years, with the improvement of environmental awareness, people have begun to pay attention to the biodegradability and environmental friendliness of flame retardants. Therefore, the development of environmentally friendly flame-retardant polyester yarn and its preparation method has become a research hotspot. Microencapsulation technology, as an effective flame retardant processing technology, can encapsulate flame retardants in a biodegradable polymer shell, thereby improving the dispersibility, stability and environmental friendliness of flame retardants. Summary of the invention

[0005] The object of the present invention is to provide a polyester flame retardant yarn and a preparation method thereof to solve the problems raised in the above background technology.

[0006] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a polyester flame-retardant yarn and a preparation method thereof, wherein the yarn is made of modified polyester fiber containing a microencapsulated flame-retardant additive, wherein the microencapsulated flame-retardant additive is a phosphorus-nitrogen composite flame retardant, specifically a mixture of triethyl phosphate and melamine in a precise ratio of 2.2:1, and its surface is wrapped by a biodegradable polymer shell layer composed of polylactic acid PLA, and is evenly dispersed inside the polyester fiber, so that the yarn reaches the V-0 flame retardant standard in a vertical burning test, while maintaining the original physical properties, environmental protection and biocompatibility of the fiber; the total addition amount of the flame-retardant additive is 10.5% of the total weight of the polyester fiber, and the particle size after microencapsulation is controlled within the range of 2-4 microns to ensure good dispersibility and lasting flame retardant effect.

[0007] Preferably, the modified polyester fiber is prepared by a co-spinning method, and before melt spinning, the microencapsulation process of the flame retardant additive adopts an ultrasonic-assisted interfacial polymerization method, wherein the ultrasonic frequency is 20kHz-40kHz and the polymerization time is 2-4 hours, so as to improve the dispersion uniformity and stability of the flame retardant additive in the polyester resin, and the flame retardant additive after microencapsulation has excellent thermal stability and chemical stability, and remains intact and does not break during the high-temperature melt spinning process. Preferably, during the melt spinning process, a twin-screw extruder with a specially designed static mixer is used for mixing, and the static mixer contains 12-16 mixing elements to ensure that the flame retardant additive microcapsules are fully mixed with the polyester resin, and the melt spinning temperature is accurately controlled within the range of 268°C-272°C to avoid microcapsule rupture, while ensuring sufficient melting of the polyester resin and smooth spinning.

[0008] Preferably, the spinneret aperture of the melt spinning machine is 0.22 mm, and the spinning speed is controlled at 3200 m / min to obtain uniform and appropriately fine flame-retardant polyester fibers while reducing energy consumption and improving production efficiency; during the spinning process, nitrogen is used as a protective gas to prevent the fibers from oxidative degradation at high temperatures.

[0009] A method for preparing polyester flame-retardant yarn, the method comprising the following steps:

[0010] a) preparing a microencapsulated flame retardant additive, mixing a flame retardant with a biodegradable polymer shell material, performing interfacial polymerization under the assistance of ultrasound to form microcapsules, wherein the weight ratio of the flame retardant to the shell material is 1:0.75, the ultrasound frequency is 30 kHz, and the polymerization time is 3 hours; b) uniformly mixing a polyester resin and a microencapsulated flame retardant additive in a predetermined ratio of 100:10.5;

[0011] c) feeding the mixture into a twin-screw extruder with a specially designed static mixer for melt mixing, the static mixer comprising 14 mixing elements;

[0012] d) sending the melt-mixed materials into a melt spinning machine for spinning to obtain polyester fibers containing flame retardant components;

[0013] e) subjecting the polyester fiber to multi-stage stretching and shaping treatment, including three stages of pre-stretching, main stretching and heat-setting, with the pre-stretching multiple controlled at 1.45 times, the main stretching multiple controlled at 4.1 times, and the heat-setting temperature controlled at 205°C, to obtain the best fiber structure and performance;

[0014] f) Twisting or plying the flame retardant polyester fibers to form flame retardant yarns.

[0015] Preferably, in step a), the biodegradable polymer shell material is polylactic acid PLA, and its molecular weight is 100,000-200,000 g / mol to ensure the stability and biodegradability of the microcapsules. During the mixing process of the flame retardant and the shell material, a small amount of surfactant is added to improve the dispersibility and stability of the microcapsules.

[0016] Preferably, in step d), the spinneret of the melt spinning machine has a special spiral design to improve the uniformity and strength of the fiber; during the spinning process, a precise temperature control system is used to ensure accurate control of the spinning temperature to avoid overheating or underheating of the fiber.

[0017] Preferably, in step e), during the multi-stage stretching process, a precise stretching control system is used to ensure accurate control of the stretching multiple to obtain the best fiber structure and performance. During the heat setting process, nitrogen is used as a protective gas to prevent the fiber from oxidative degradation at high temperatures, while improving the thermal stability and dimensional stability of the fiber.

[0018] Preferably, the method further includes a step of performing plasma surface modification treatment on the flame-retardant yarn after step f), wherein the plasma treatment conditions are: power of 50W-100W, treatment time of 30 seconds-1 minute, and gas of argon or nitrogen to improve the hydrophilicity, dyeability and adhesion to other materials of the yarn while maintaining its flame retardant properties; after plasma treatment, the surface energy of the yarn is significantly improved, which is beneficial to subsequent dyeing and finishing processes.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The polyester flame retardant yarn and preparation method thereof proposed by the present invention have the following advantages: microencapsulation treatment of the flame retardant additive improves the dispersibility and stability of the flame retardant in the polyester fiber, thereby ensuring the long-lasting flame retardant effect of the yarn; a twin-screw extruder with a specially designed static mixer is used for mixing during the melt spinning process, thereby ensuring the full mixing of the flame retardant additive microcapsules with the polyester resin; and plasma surface modification treatment improves the hydrophilicity, dyeability and adhesion to other materials of the yarn, which is beneficial to the subsequent dyeing and finishing processes and increases the added value of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The figure is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0022] In order to make the purpose and technical solution of the present invention clearly and completely described, and the advantages more clearly understood, the embodiments of the present invention are further described in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are part of the embodiments of the present invention, rather than all of the embodiments, and are only used to explain the embodiments of the present invention, and are not used to limit the embodiments of the present invention. All other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] Embodiment 1, the present invention provides a technical solution: preparation of polyester flame retardant yarn.

[0024] Overview of steps:

[0025] Preparation of microencapsulated flame retardant additive: Flame retardant: triethyl phosphate and melamine are mixed in a ratio of 2.2:1. Shell material: polylactic acid (PLA), molecular weight 150,000g / mol. Surfactant: Added in small amounts to improve dispersibility. Ultrasonic frequency: 30kHz. Polymerization time: 3 hours. Particle size after microencapsulation: 2-4 microns.

[0026] Preparation of modified polyester fiber: Ratio of polyester resin to flame retardant additive: 100:10.5. Twin screw extruder: Specially designed static mixer with 14 mixing elements. Melt spinning temperature: 270°C. Spinning speed: 3200 m / min. Nitrogen protection.

[0027] Fiber stretching and shaping: Pre-stretching ratio: 1.45 times. Main stretching ratio: 4.1 times. Heat setting temperature: 205℃.

[0028] Yarn preparation: Flame retardant polyester fibers are twisted or plied.

[0029] Results: The flame retardant polyester yarn achieved V-0 flame retardancy in the vertical burning test. The yarn maintained the original physical properties, environmental protection and biocompatibility of polyester fiber.

[0030] Example 2, based on Example 1, proposes an overview of the optimized steps of the microencapsulation process (basically the same as Example 1, but the microencapsulation process is different):

[0031] Preparation of microencapsulated flame retardant additives: The ultrasonic frequency was adjusted to 25 kHz and the polymerization time was extended to 3.5 hours.

[0032] Other steps: the same as in Example 1.

[0033] Results: The microencapsulated flame retardant additive has higher dispersibility and stability. The flame retardant performance of the yarn is slightly improved and still reaches the V-0 standard.

[0034] Embodiment 3, based on Embodiment 1, proposes an overview of the adjustment steps of the spinning parameters (basically the same as Embodiment 1, but the spinning parameters are different):

[0035] Melt spinning process: The melt spinning temperature was adjusted to 269°C and the spinning speed was increased to 3300 m / min.

[0036] Other steps: the same as in Example 1.

[0037] Result: The yarn production efficiency is improved. The yarn fineness is more uniform and the physical properties are slightly improved. The flame retardant performance of the yarn still meets the V-0 standard.

[0038] Embodiment 4, based on embodiment 1, proposes an overview of the steps of plasma surface modification treatment (adding plasma surface modification treatment on the basis of embodiment 1):

[0039] Plasma surface modification treatment: Power: 75 W. Treatment time: 45 seconds. Gas: Argon.

[0040] Other steps: the same as in Example 1, until the yarn is prepared. After the yarn is prepared, plasma surface modification treatment is performed.

[0041] Results: The hydrophilicity, dyeability and adhesion to other materials of the yarn are significantly improved. The surface energy of the yarn is increased, which is beneficial for the subsequent dyeing and finishing processes. The flame retardant properties of the yarn still meet the V-0 standard and are not affected by the plasma treatment.

[0042] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A polyester flame retardant yarn, characterized in that: The yarn is made of modified polyester fiber containing microencapsulated flame retardant additives. The microencapsulated flame retardant additive is a phosphorus-nitrogen composite flame retardant, specifically a mixture of triethyl phosphate and melamine in a precise ratio of 2.2:

1. Its surface is wrapped by a biodegradable polymer shell composed of polylactic acid PLA and evenly dispersed inside the polyester fiber, so that the yarn meets the V-0 flame retardant standard in the vertical burning test while maintaining the original physical properties, environmental protection and biocompatibility of the fiber; the total amount of flame retardant additives added is 10.5% of the total weight of the polyester fiber, and the particle size after microencapsulation is controlled in the range of 2-4 microns to ensure good dispersibility and lasting flame retardant effect.

2. The polyester flame retardant yarn according to claim 1, characterized in that: The modified polyester fiber is prepared by a blending spinning method, and before melt spinning, the microencapsulation process of the flame retardant additive adopts an ultrasonic-assisted interfacial polymerization method, wherein the ultrasonic frequency is 20kHz-40kHz and the polymerization time is 2-4 hours, so as to improve the dispersion uniformity and stability of the flame retardant additive in the polyester resin. The microencapsulated flame retardant additive has excellent thermal stability and chemical stability, and remains intact and does not break during the high-temperature melt spinning process.

3. The polyester flame retardant yarn according to claim 2, characterized in that: During the melt spinning process, a twin-screw extruder with a specially designed static mixer is used for mixing. The static mixer contains 12-16 mixing elements to ensure the full mixing of the flame retardant additive microcapsules with the polyester resin. The melt spinning temperature is precisely controlled within the range of 268°C-272°C to avoid microcapsule rupture, while ensuring the full melting of the polyester resin and the smooth progress of the spinning process.

4. The polyester flame-retardant yarn according to claim 1, characterized in that: The spinneret aperture of the melt spinning machine is 0.22mm, and the spinning speed is controlled at 3200m / min to obtain uniform and appropriately fine flame-retardant polyester fibers while reducing energy consumption and improving production efficiency. During the spinning process, nitrogen is used as a protective gas to prevent the fibers from oxidative degradation at high temperatures.

5. A method for preparing the polyester flame retardant yarn according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: a) preparing a microencapsulated flame retardant additive, mixing a flame retardant with a biodegradable polymer shell material, and performing interfacial polymerization under the assistance of ultrasound to form microcapsules, wherein the weight ratio of the flame retardant to the shell material is 1:0.75, the ultrasound frequency is 30 kHz, and the polymerization time is 3 hours; b) mixing the polyester resin and the microencapsulated flame retardant additive in a predetermined ratio of 100:10.5; c) feeding the mixture into a twin-screw extruder with a specially designed static mixer for melt mixing, the static mixer comprising 14 mixing elements; d) sending the melt-mixed materials into a melt spinning machine for spinning to obtain polyester fibers containing flame retardant components; e) subjecting the polyester fiber to multi-stage stretching and shaping treatment, including three stages of pre-stretching, main stretching and heat-setting, with the pre-stretching multiple controlled at 1.45 times, the main stretching multiple controlled at 4.1 times, and the heat-setting temperature controlled at 205°C, to obtain the best fiber structure and performance; f) Twisting or plying the flame retardant polyester fibers to form flame retardant yarns.

6. The method for preparing a polyester flame-retardant yarn according to claim 5, characterized in that: In step a), the biodegradable polymer shell material is polylactic acid PLA, and its molecular weight is 100,000-200,000 g / mol to ensure the stability and biodegradability of the microcapsules. During the mixing process of the flame retardant and the shell material, a small amount of surfactant is added to improve the dispersibility and stability of the microcapsules.

7. The method for preparing a polyester flame-retardant yarn according to claim 1, characterized in that: In step d), the spinneret of the melt spinning machine has a special spiral design to improve the uniformity and strength of the fiber; during the spinning process, a precise temperature control system is used to ensure accurate control of the spinning temperature to avoid overheating or underheating of the fiber.

8. The method for preparing a polyester flame-retardant yarn according to claim 1, characterized in that: In step e), during the multi-stage stretching process, a precise stretching control system is used to ensure accurate control of the stretching multiple to obtain the best fiber structure and performance. During the heat setting process, nitrogen is used as a protective gas to prevent the fiber from oxidative degradation at high temperatures, while improving the thermal stability and dimensional stability of the fiber.

9. The method for preparing a polyester flame-retardant yarn according to claim 1, characterized in that: The method further includes the step of performing plasma surface modification treatment on the flame retardant yarn after step f), wherein the plasma treatment conditions are: power of 50W-100W, treatment time of 30 seconds-1 minute, and gas of argon or nitrogen, so as to improve the hydrophilicity, dyeability and adhesion to other materials of the yarn while maintaining its flame retardant properties; after plasma treatment, the surface energy of the yarn is significantly improved, which is beneficial to the subsequent dyeing and finishing processes.

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