Preparation method of high-performance flame-retardant polyester yarn using composite flame retardant

Abstract

The invention relates to the technical field of high polymer material processing, in particular to a preparation method of high-performance flame-retardant polyester yarn using a composite flame retardant. The method comprises the following steps: compounding a phosphorus flame retardant (aluminum hypophosphite and aluminum diethylphosphinate), a nitrogen flame retardant (melamine cyanurate and melamine polyphosphate) and a nano synergist (silane modified nano montmorillonite), carrying out high-speed shearing and ultrasonic dispersion to prepare a nano composite flame retardant suspension, and carrying out melt blending on the nano composite flame retardant suspension and polyester chips to prepare the flame-retardant master batch. The limit oxygen index of the yarn is larger than or equal to 32%, the breaking strength is larger than or equal to 3.5 cN / dtex, the flame retardant property retention rate after 50 times of water washing is larger than or equal to 90%, efficient flame retardance and excellent mechanical property are achieved, and the flame-retardant polyester yarn is suitable for the field of textiles with the high fireproof safety requirement.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer material processing, and in particular to a method for preparing high-performance flame-retardant polyester yarn using a composite flame retardant. Background Art

[0002] Polyester fiber is widely used in textiles and industrial textiles due to its excellent mechanical properties, chemical stability, and low cost. However, the inherent flammability of polyester restricts its application in applications requiring high fire safety, such as vehicle interiors, protective clothing, and architectural decorative materials. Traditional flame-retardant modification methods often use additive flame retardants, but these methods suffer from low flame retardant efficiency, high additive dosages, and impacts on the fiber's mechanical and processing properties.

[0003] Halogen-based flame retardants offer high flame retardancy but tend to release toxic gases when burned. Phosphorus-based flame retardants are environmentally friendly, but a single component cannot meet high performance requirements. Inorganic flame retardants (such as aluminum hydroxide and zinc borate) are non-toxic, but excessive addition can cause fiber embrittlement. Therefore, developing a composite flame retardant system that combines high flame retardancy with excellent mechanical properties and stable processing, and establishing a corresponding polyester yarn preparation process, has become a pressing technical challenge in this field. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing high-performance flame-retardant polyester yarn using a composite flame retardant, so as to solve the problems raised in the background technology and facilitate promotion.

[0005] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0006] A method for preparing high-performance flame-retardant polyester yarn using a composite flame retardant comprises the following steps:

[0007] (1) Preparation of composite flame retardant: Phosphorus flame retardant, nitrogen flame retardant, and nano synergist were mixed in a mass ratio of (40-60):(20-35):(5-15), and subjected to high-speed shear dispersion and ultrasonic treatment to obtain a composite flame retardant suspension with a particle size distribution of D50 ≤ 200 nm;

[0008] (2) Preparation of masterbatch: The composite flame retardant suspension obtained in step (1) is mixed with polyester chips in a mass ratio of (15-30): (70-85), melt-blended by a twin-screw extruder, and then pelletized underwater to obtain a flame retardant masterbatch;

[0009] (3) Preparation of spinning solution: The flame retardant masterbatch obtained in step (2) is mixed with conventional polyester chips in a mass ratio of (25-40): (60-75), and the mixture is dried, melted, and filtered to obtain a spinning solution containing a composite flame retardant;

[0010] (4) melt spinning: the spinning solution obtained in step (3) is transported to a spinneret via a metering pump, and melt spinning is performed at a spinning temperature of 280-305°C and a winding speed of 3000-4500 m / min to produce spun fibers;

[0011] (5) post-processing: the spun fibers obtained in step (4) are sequentially oiled, stretched, heat-set, and wound to obtain high-performance flame-retardant polyester yarn;

[0012] Among them, the phosphorus-based flame retardant in the composite flame retardant is at least one of aluminum hypophosphite and diethyl aluminum phosphinate; the nitrogen-based flame retardant is at least one of melamine cyanurate and polyphosphate melamine; and the nanosynergist is at least one of nano-montmorillonite, nano-silica, and carbon nanotubes.

[0013] Furthermore, in step (1):

[0014] The phosphorus-based flame retardant is a mixture of aluminum hypophosphite and aluminum diethylphosphinate, with a mass ratio of (60-80):(20-40);

[0015] The nitrogen-based flame retardant is a mixture of melamine cyanurate and melamine polyphosphate in a mass ratio of (50-70):(30-50);

[0016] The nano synergist is nano montmorillonite surface-modified by a silane coupling agent, and the dosage of the modifier is 1-3% of the mass of the nano montmorillonite.

[0017] Furthermore, in step (1):

[0018] The process parameters of high-speed shear dispersion are: speed 3000-5000rpm, time 10-30min;

[0019] The process parameters of ultrasonic treatment are: frequency 20-40kHz, power 500-1000W, time 5-15min;

[0020] The solid content of the composite flame retardant suspension is 30-45 wt %.

[0021] Furthermore, in step (2):

[0022] The processing temperature of the twin-screw extruder is 250-280°C and the screw speed is 200-400 rpm;

[0023] The flame retardant masterbatch has an intrinsic viscosity of 0.6-0.8 dL / g and a melt index of 20-35 g / 10 min (275° C. / 2.16 kg).

[0024] Furthermore, in step (3):

[0025] Drying process: drying at 120-150℃ for 4-6h, controlling the moisture content ≤30ppm;

[0026] The melting temperature is 275-295℃ and the filtration accuracy is 10-20μm.

[0027] Furthermore, in step (5):

[0028] The oiling process uses an emulsion with an oil concentration of 8-12wt% and an oil attachment amount of 0.8-1.5wt%;

[0029] The stretching process is: total stretching ratio 3.5-5.0 times, divided into two stages, the first stage stretching temperature is 80-100℃, and the second stage stretching temperature is 120-150℃;

[0030] Heat setting process: temperature 160-190℃, time 0.5-2.0min;

[0031] The winding speed is 3500-5000m / min.

[0032] Furthermore, a synergistic flame retardant component is added to the composite flame retardant. The synergistic flame retardant component is at least one of zinc borate and molybdenum oxide, and its amount is 2-8% of the total mass of the composite flame retardant.

[0033] Furthermore, in step (4), the spinneret aperture is 0.2-0.4 mm, the aspect ratio is (2-4):1, and the filter mesh number of the spinneret assembly is 80-120 meshes.

[0034] Furthermore, the limiting oxygen index is ≥32%; the vertical burning test reaches UL94 V-0 grade; the breaking strength is ≥3.5cN / dtex, and the elongation at break is 25-35%; after 50 water washes, the limiting oxygen index retention rate is ≥90%; and after treatment in 260°C hot air for 30 minutes, the strength retention rate is ≥85%.

[0035] As an improvement, the beneficial effects of the present invention are:

[0036] 1. Significantly improved flame retardancy: The synergistic effect of the composite flame retardant increases the limiting oxygen index (LOI) to over 32%, and vertical combustion reaches UL94 V-0 level, which is 20-30% higher than traditional flame retardant polyester;

[0037] 2. Excellent mechanical properties: breaking strength ≥3.5cN / dtex, elongation at break 25-35%, meeting the demand for high-strength industrial yarn;

[0038] 3. Outstanding durability: LOI retention rate ≥90% after 50 water washes, strength retention rate ≥85% after 260℃ heat treatment for 30min;

[0039] 4. Good processing stability: The flame retardant is evenly dispersed through masterbatch technology, the spinning breakage rate is ≤0.5 times / ton, and continuous and stable production is possible. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a comparison chart of test results of a method for preparing high-performance flame-retardant polyester yarn using a composite flame retardant according to the present invention; DETAILED DESCRIPTION

[0041] In order to make the contents of the present invention more clearly understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0042] Example 1

[0043] (1) Preparation of composite flame retardant: Aluminum hypophosphite (60 wt%), aluminum diethylphosphinate (40 wt%), melamine cyanurate (50 wt%), melamine polyphosphate (50 wt%), and silane-modified nano-montmorillonite (15 wt%) were mixed and subjected to high-speed shearing (4000 rpm, 20 min) and ultrasonic treatment (28 kHz, 800 W, 10 min) to prepare a suspension with a solid content of 40 wt%;

[0044] (2) Preparation of masterbatch: The composite flame retardant suspension and polyester chips were mixed at a ratio of 25:75 and melt-blended in a twin-screw extruder (260°C, 300 rpm) to obtain a masterbatch with an intrinsic viscosity of 0.72 dL / g;

[0045] (3) Preparation of spinning solution: Mix the masterbatch with conventional polyester chips at a ratio of 30:70, dry, melt (285°C), and filter (15 μm);

[0046] (4) Melt spinning: spinning temperature 290 °C, winding speed 4000 m / min;

[0047] (5) Post-treatment: oiling (oil concentration 10 wt%, adhesion 1.2 wt%), two-stage stretching (total multiple 4.2 times, first stage 90 ° C, second stage 130 ° C), heat setting (180 ° C, 1.0 min), winding speed 4500 m / min.

[0048] Example 2

[0049] Based on Example 1, zinc borate (5 wt %) was added to the composite flame retardant, and the other process parameters remained unchanged.

[0050] Example 3

[0051] The ratio of aluminum hypophosphite to aluminum diethylphosphinate in the composite flame retardant was adjusted to 70:30, and the ratio of melamine cyanurate to melamine polyphosphate was adjusted to 60:40. The rest was the same as in Example 1.

[0052] Example 4

[0053] The spinning temperature was adjusted to 300° C. and the winding speed was 4500 m / min. The rest was the same as in Example 1.

[0054] Example 5

[0055] The heat setting temperature was adjusted to 170° C. and the time was 1.5 min. The rest was the same as in Example 1.

[0056] Example 6

[0057] The addition of zinc borate was omitted, and the rest was the same as in Example 1.

[0058] Comparative Example 1

[0059] Aluminum primary phosphate was used as a flame retardant in an amount of 20 wt %. The remaining processes were the same as in Example 1.

[0060] Comparative Example 2

[0061] No nanosynergist was added, and the rest was the same as in Example 1

[0062] Through the design of a composite flame retardant system and full-process process control, the present invention achieves a synergistic improvement in the flame retardant properties and mechanical properties of polyester yarn, showing significant advantages in durability and processing stability, and can be widely used in firefighting uniforms, automotive interiors, electrical insulation materials and other fields.

[0063] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A method for preparing high-performance flame-retardant polyester yarn using a composite flame retardant, characterized in that: The following steps are included: (1) Preparation of composite flame retardant: Phosphorus flame retardant, nitrogen flame retardant, and nano synergist were mixed in a mass ratio of (40-60):(20-35):(5-15), and subjected to high-speed shear dispersion and ultrasonic treatment to obtain a composite flame retardant suspension with a particle size distribution of D50 ≤ 200 nm; (2) Preparation of masterbatch: The composite flame retardant suspension obtained in step (1) is mixed with polyester chips in a mass ratio of (15-30): (70-85), melt-blended by a twin-screw extruder, and then pelletized underwater to obtain a flame retardant masterbatch; (3) Preparation of spinning solution: The flame retardant masterbatch obtained in step (2) is mixed with conventional polyester chips in a mass ratio of (25-40): (60-75), and the mixture is dried, melted, and filtered to obtain a spinning solution containing a composite flame retardant; (4) melt spinning: the spinning solution obtained in step (3) is transported to a spinneret via a metering pump, and melt spinning is performed at a spinning temperature of 280-305°C and a winding speed of 3000-4500 m / min to produce spun fibers; (5) post-processing: the spun fibers obtained in step (4) are sequentially oiled, stretched, heat-set, and wound to obtain high-performance flame-retardant polyester yarn; Among them, the phosphorus-based flame retardant in the composite flame retardant is at least one of aluminum hypophosphite and diethyl aluminum phosphinate; the nitrogen-based flame retardant is at least one of melamine cyanurate and polyphosphate melamine; and the nanosynergist is at least one of nano-montmorillonite, nano-silica, and carbon nanotubes.

2. The method for preparing high-performance flame-retardant polyester yarn using a composite flame retardant according to claim 1, characterized in that: In the step (1): The phosphorus-based flame retardant is a mixture of aluminum hypophosphite and aluminum diethylphosphinate, with a mass ratio of (60-80):(20-40); The nitrogen-based flame retardant is a mixture of melamine cyanurate and melamine polyphosphate in a mass ratio of (50-70):(30-50); The nano synergist is nano montmorillonite surface-modified by a silane coupling agent, and the dosage of the modifier is 1-3% of the mass of the nano montmorillonite.

3. The method for preparing high-performance flame-retardant polyester yarn using a composite flame retardant according to claim 1, characterized in that: In the step (1): The process parameters of high-speed shear dispersion are: speed 3000-5000rpm, time 10-30min; The process parameters of ultrasonic treatment are: frequency 20-40kHz, power 500-1000W, time 5-15min; The solid content of the composite flame retardant suspension is 30-45 wt %.

4. The method for preparing high-performance flame-retardant polyester yarn using a composite flame retardant according to claim 1, characterized in that: In the step (2): The processing temperature of the twin-screw extruder is 250-280°C and the screw speed is 200-400 rpm; The flame retardant masterbatch has an intrinsic viscosity of 0.6-0.8 dL / g and a melt index of 20-35 g / 10 min (275° C. / 2.16 kg).

5. The method for preparing high-performance flame-retardant polyester yarn using a composite flame retardant according to claim 1, characterized in that: In the step (3): Drying process: drying at 120-150℃ for 4-6h, controlling the moisture content ≤30ppm; The melting temperature is 275-295℃ and the filtration accuracy is 10-20μm.

6. The method for preparing high-performance flame-retardant polyester yarn using a composite flame retardant according to claim 1, characterized in that: In the step (5): The oiling process uses an emulsion with an oil concentration of 8-12wt% and an oil attachment amount of 0.8-1.5wt%; The stretching process is: total stretching ratio 3.5-5.0 times, divided into two stages, the first stage stretching temperature is 80-100℃, and the second stage stretching temperature is 120-150℃; Heat setting process: temperature 160-190℃, time 0.5-2.0min; The winding speed is 3500-5000m / min.

7. The method for preparing high-performance flame-retardant polyester yarn using a composite flame retardant according to claim 1, characterized in that: The composite flame retardant is further added with a synergistic flame retardant component, which is at least one of zinc borate and molybdenum oxide, and its amount is 2-8% of the total mass of the composite flame retardant.

8. The method for preparing high-performance flame-retardant polyester yarn using a composite flame retardant according to claim 1, characterized in that: In the step (4), the spinneret aperture is 0.2-0.4 mm, the aspect ratio is (2-4):1, and the filter mesh number of the spinneret assembly is 80-120 meshes.

9. A method for preparing high-performance flame-retardant polyester yarn using a composite flame retardant according to any one of claims 1 to 8, characterized in that: Limiting oxygen index ≥32%; vertical burning test reaches UL94 V-0 grade; breaking strength ≥3.5cN / dtex, elongation at break 25-35%; after 50 water washes, limiting oxygen index retention rate ≥90%; after treatment in 260℃ hot air for 30 minutes, strength retention rate ≥85%.

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