Flame-retardant polyester fiber and preparation method thereof

Abstract

The invention belongs to the technical field of polyester fibers, and particularly provides a flame-retardant polyester fiber and a preparation method thereof.The polyester fiber is prepared from, by weight, 50-70 parts of polyester chips, 6-10 parts of flame-retardant polyester master batch and 1-2 parts of antioxidant; wherein the flame-retardant polyester master batch is obtained by extruding and granulating a montmorillonite-based flame retardant and polyester powder. According to the invention, the montmorillonite-based flame retardant is introduced into the polyester fiber, so that the polyester fiber has excellent flame retardance and anti-dripping effect.

Description

Technical Field

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

[0002] Polyester fiber has become one of the most widely used synthetic fibers due to its excellent mechanical properties, chemical stability, and fatigue resistance. However, polyester fiber is a flammable material with a limiting oxygen index (LOI) of approximately 20%-22%, which fails to meet the flame retardancy requirements of some specialized applications, limiting its widespread application. Furthermore, polyester fiber is prone to forming droplets during combustion, potentially causing serious secondary damage. Therefore, the development of polyester fibers with flame retardant and droplet-resistant properties is of great practical significance.

[0003] In recent years, researchers have achieved flame-retardant modification of polyester by introducing phosphorus-based polymer flame retardants with excellent char-forming properties into polyester melts through chemical modification. Furthermore, studies have also investigated improving the flame retardancy and anti-drip properties of polyester fibers by coating them with polyaniline. These studies provide a theoretical basis and technical support for the development of high-performance, anti-drip, flame-retardant polyester fibers. Chinese patent CN 106521691 B discloses a polyester fiber with flame-retardant and antibacterial properties and its applications. The polyester fiber comprises raw materials: polyester resin, polyimide, nano-swelling agent, basalt fiber, 8-hydroxyquinoline copper, a flame retardant, starch ether, an initiator, a silane coupling agent, a dispersant, and a surfactant. This invention exhibits excellent antibacterial and flame-retardant properties, antistatic properties, acid and alkali resistance, and hygroscopicity. However, some of the flame retardants used in the polyester fibers produced by this invention contain halogens. Halogen-containing flame retardants can release harmful gases at high temperatures, potentially harming the ecological environment and human health.

[0004] Therefore, there is an urgent need for a polyester fiber that does not release toxic gases and has good flame retardant and anti-melting dripping effects. Summary of the Invention

[0005] In view of the existing technical problems, the purpose of the present invention is to provide a flame-retardant polyester fiber and a preparation method thereof. The present invention introduces a montmorillonite-based flame retardant into the polyester fiber, so that the polyester fiber has excellent flame retardancy and anti-dripping effect.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] On the one hand, the present invention provides a flame-retardant polyester fiber, which comprises the following raw materials, by weight: 50-70 parts of polyester chips, 6-10 parts of flame-retardant polyester masterbatch, and 1-2 parts of antioxidant; wherein the flame-retardant polyester masterbatch is obtained by granulating a montmorillonite-based flame retardant and polyester powder.

[0008] The reaction mechanism and effects of the present invention are as follows:

[0009] The montmorillonite of the present invention has significant flame retardant and anti-melting droplet effects in polyester fibers. The present invention first treats the montmorillonite with phosphoric acid. A large number of acidic sites (including Bronsted acid sites and Lewis acid sites) are formed on the surface of the acidified montmorillonite, which can catalyze the carbonization reaction of the polyester fiber during the combustion process and promote the formation of a stable carbon layer, thereby improving the thermal stability and residual carbon rate of the fiber. Then, the applicant modified the montmorillonite with an aminosilane coupling agent, increasing its interlayer spacing, which helps the reactants to better graft on the surface of the silanized montmorillonite and between the layers to form a montmorillonite-based flame retardant. More importantly, the boric acid group and benzene ring structure contained in the reactant obtained by the reaction of 3-aminophenylboronic acid and 3,4-dihydroxybenzaldehyde can jointly catalyze the carbonization process of the fiber and promote the formation of a carbon layer. This carbonized layer has good heat insulation and oxygen isolation effects, can effectively prevent the transfer of heat and oxygen, and reduce the formation of melt drops.

[0010] In some embodiments, the method for preparing the montmorillonite-based flame retardant comprises the following steps:

[0011] S1. The montmorillonite was washed, dried, added to a 2-4% volume concentration of aqueous phosphoric acid solution, stirred, filtered, washed, and dried to obtain acidified montmorillonite;

[0012] S2. Mix the aminosilane coupling agent, methanol, and water, heat to 50-55°C, adjust the pH to 4-5.5, stir at constant temperature for 30-60 min, add the acidified montmorillonite obtained in step S1, heat to 55-65°C, react for 1-2 h, wash, centrifuge, repeat 2-3 times, and dry at 85-90°C to obtain silanized montmorillonite;

[0013] S3. Add 3-aminophenylboronic acid and 3,4-dihydroxybenzaldehyde to a mixed solution of ethanol and water, stir and react at 35-50 ° C for 3-6 hours, protect from light throughout the reaction, and distill under reduced pressure until the mixed solution of ethanol and water remains 1 / 4-1 / 3, wash, and dry to obtain a reactant;

[0014] S4. The silanized montmorillonite obtained in step S2, the reactant obtained in step S3, and ethanol are mixed, heated and stirred to react for 8-12 hours, filtered, and dried to obtain a montmorillonite-based flame retardant.

[0015] In some embodiments, the aminosilane coupling agent in step S2 is 3-aminopropyl-triethoxysilane and / or N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane.

[0016] In some embodiments, the mass ratio of the aminosilane coupling agent to the acidified montmorillonite in step S2 is 1:(1.5-3.5).

[0017] In some embodiments, the molar ratio of 3-aminophenylboronic acid to 3,4-dihydroxybenzaldehyde in step S3 is (2.05-2.2):1.

[0018] In some embodiments, the mass ratio of the silanized montmorillonite to the reactant in step S4 is 1:(1-2).

[0019] In some embodiments, the mass ratio of the montmorillonite-based flame retardant to the polyester powder is 1:(4-5).

[0020] In some embodiments, the method for preparing the flame retardant polyester masterbatch comprises the following steps:

[0021] The polyester powder is first dried at 120-130°C for 10-12 hours, and then the montmorillonite-based flame retardant and polyester powder are mixed and put into a twin-screw extruder for melt blending and extrusion granulation. The processing temperature of the twin-screw extruder is 250-260°C and the processing speed is 20-25r / min to obtain a flame-retardant polyester masterbatch.

[0022] In some embodiments, the antioxidant is a hindered phenol antioxidant and / or a phosphite antioxidant.

[0023] Another aspect of the present invention provides a method for preparing a flame-retardant polyester fiber, comprising the following steps:

[0024] Q1. Add flame-retardant polyester masterbatch, polyester chips, and antioxidant into a mixer and stir to obtain a mixture;

[0025] Q2. The mixture obtained in step Q1 is added to a twin-screw extruder for extrusion granulation. The processing temperature of the twin-screw extruder is 250-260°C and the processing speed is 20-25r / min. After melt blending and extrusion granulation, melt spinning is performed, and after cooling, oiling, pre-stretching, winding, and stretching, a flame-retardant polyester fiber is obtained.

[0026] In some embodiments, the process parameters of the melt spinning are: spinning speed of 2600-2800 m / min, spinning temperature of 270-280° C., and drawing ratio of 1.5-2 times.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The present invention introduces a montmorillonite-based flame retardant into the polyester fiber, so that the polyester fiber has excellent flame retardancy and anti-drip effect.

[0029] 2. The layered structure, acidic sites and benzene ring structure of the montmorillonite-based flame retardant of the present invention have a synergistic effect, which not only helps to promote carbonization, but also enhances the quality of the carbon layer, making the thermal stability and mechanical strength of the carbon layer good, and further reducing the formation of molten droplets. DETAILED DESCRIPTION

[0030] The present invention will be described below in conjunction with specific embodiments. It should be noted that the following examples are illustrative of the present invention and are intended only to illustrate the present invention, not to limit the present invention. Other combinations and various modifications within the scope of the present invention may be made without departing from the spirit or scope of the present invention.

[0031] Polyester fibers were prepared according to the ratios of the raw materials and the preparation methods specified in the following examples and comparative examples.

[0032] In order to facilitate those skilled in the art to implement the present invention, some raw material manufacturers of the embodiments and comparative examples are described as follows:

[0033] Polyester powder: polyethylene terephthalate, purchased from Shanghai Yizeng Plasticizing Co., Ltd., model PET-C powder, mesh size 150 mesh;

[0034] Polyester chips: polyethylene terephthalate, purchased from Guangdong Pengcheng Shihai New Materials Co., Ltd., model PET-P1000;

[0035] Montmorillonite: purchased from Zhejiang Fenghong New Materials Co., Ltd., particle size 200 mesh;

[0036] Unless otherwise specified, other raw materials can be purchased from the market.

[0037] Preparation Example 1

[0038] The preparation method of montmorillonite-based flame retardant A comprises the following steps:

[0039] S1. 200g of montmorillonite was filtered with deionized water three times, dried at 75 ° C to constant weight, cooled to room temperature and added to 800mL of a 3% aqueous phosphoric acid solution, stirred, filtered, washed four times with deionized water, and dried at 75 ° C to constant weight to obtain acidified montmorillonite;

[0040] S2. 20 g of N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane, 800 g of methanol, and 200 g of deionized water were mixed, heated to 55 ° C, adjusted to pH 5.0 with glacial acetic acid, and stirred at constant temperature for 45 min. 50 g of acidified montmorillonite obtained in step S1 was added, and the temperature was raised to 60 ° C for 1.5 h. The mixture was washed with methanol and centrifuged, and the mixture was repeated three times. The mixture was dried at 85 ° C to constant weight to obtain silanized montmorillonite;

[0041] S3. 20 g of 3-aminophenylboronic acid and 20 g of 3,4-dihydroxybenzaldehyde were added to 200 mL of a mixed solution of ethanol and deionized water (the volume ratio of ethanol to deionized water was 1.5:1), stirred at 45 ° C for 5 h, protected from light throughout the reaction, and distilled under reduced pressure until the mixed solution of ethanol and deionized water remained 1 / 4, washed three times with ethanol, purified, and dried at 75 ° C to constant weight to obtain the reactant;

[0042] S4. Mix 20 g of silanized montmorillonite obtained in step S2, 30 g of the reactant obtained in step S3, and 150 g of ethanol, heat to 65 ° C, stir and react for 10 h, filter, and dry at 75 ° C to constant weight to obtain montmorillonite-based flame retardant A.

[0043] Preparation Example 2

[0044] The preparation method of montmorillonite-based flame retardant B is the same as that of Preparation Example 1, except that the amount of 3-aminophenylboronic acid added in step S3 is 10 g.

[0045] Preparation Example 3

[0046] The preparation method of montmorillonite-based flame retardant C is the same as that of Preparation Example 1, except that the amount of reactants added in step S4 is 18 g.

[0047] Example 1

[0048] A flame-retardant polyester fiber comprises the following raw materials, measured by weight: 60 parts of polyethylene terephthalate, 8 parts of flame-retardant polyester masterbatch, and 10101.5 parts of an antioxidant; wherein the flame-retardant polyester masterbatch is obtained by granulating a montmorillonite-based flame retardant A and polyester powder, and the mass ratio of the flame retardant and polyester powder is 1:4.5.

[0049] The method for preparing the polyester fiber of this embodiment comprises the following steps:

[0050] Q1. Polyester powder was dried at 125°C for 11 hours. Montmorillonite-based flame retardant A and polyester powder were then mixed and fed into a twin-screw extruder for melt blending and extrusion granulation. The twin-screw extruder was operated at a temperature of 255°C and a speed of 22 rpm to obtain a flame-retardant polyester masterbatch. The flame-retardant polyester masterbatch, polyethylene terephthalate, and antioxidant 1010 were added to the mixer and stirred uniformly to obtain a mixture.

[0051] Q2. The mixture obtained in step Q1 was extruded into a twin-screw extruder at a processing temperature of 255°C and a processing speed of 22 r / min. The mixture was melt-blended, extruded into granules, and then melt-spun. After cooling, the mixture was oiled, pre-stretched, wound, and stretched to obtain a flame-retardant polyester fiber. The process parameters of the melt spinning were: a spinning speed of 2700 m / min, a spinning temperature of 275°C, and a draw ratio of 1.5.

[0052] Example 2

[0053] A flame-retardant polyester fiber comprises the following raw materials, measured by weight: 50 parts of polyethylene terephthalate, 6 parts of flame-retardant polyester masterbatch, and 10101 parts of an antioxidant; wherein the flame-retardant polyester masterbatch is obtained by granulating a montmorillonite-based flame retardant A and polyester powder, and the mass ratio of the flame retardant and polyester powder is 1:4.

[0054] The method for preparing the polyester fiber of this embodiment comprises the following steps:

[0055] Q1. Polyester powder was dried at 120°C for 12 hours. Montmorillonite-based flame retardant A and polyester powder were then mixed and fed into a twin-screw extruder for melt blending and extrusion granulation. The twin-screw extruder was operated at a temperature of 250°C and a speed of 25 rpm to obtain a flame-retardant polyester masterbatch. The flame-retardant polyester masterbatch, polyethylene terephthalate, and antioxidant 1010 were added to the mixer and stirred uniformly to obtain a mixture.

[0056] Q2. The mixture obtained in step Q1 is extruded into a twin-screw extruder at a processing temperature of 250°C and a processing speed of 25 r / min. The mixture is melt-blended, extruded into granules, and then melt-spun. After cooling, the mixture is oiled, pre-stretched, wound, and stretched to obtain a flame-retardant polyester fiber. The process parameters of the melt spinning are: a spinning speed of 2600 m / min, a spinning temperature of 270°C, and a drawing ratio of 1.5 times.

[0057] Example 3

[0058] A flame-retardant polyester fiber comprises the following raw materials, measured in parts by weight: 70 parts of polyethylene terephthalate, 10 parts of flame-retardant polyester masterbatch, and 10102 parts of an antioxidant; wherein the flame-retardant polyester masterbatch is obtained by granulating a montmorillonite-based flame retardant A and polyester powder, and the mass ratio of the flame retardant and polyester powder is 1:5.

[0059] The method for preparing the polyester fiber of this embodiment comprises the following steps:

[0060] Q1. Polyester powder was dried at 130°C for 10 hours. Montmorillonite-based flame retardant A and polyester powder were then mixed and fed into a twin-screw extruder for melt blending and extrusion granulation. The twin-screw extruder was operated at a temperature of 260°C and a speed of 20 r / min to obtain a flame-retardant polyester masterbatch. The flame-retardant polyester masterbatch, polyethylene terephthalate, and antioxidant 1010 were added to the mixer and stirred uniformly to obtain a mixture.

[0061] Q2. The mixture obtained in step Q1 is added to a twin-screw extruder for extrusion and granulation. The processing temperature of the twin-screw extruder is 260°C and the processing speed is 20 r / min. After melt blending and extrusion granulation, melt spinning is performed. After cooling, oiling, pre-stretching, winding, and stretching are performed to obtain a flame-retardant polyester fiber. The process parameters of the melt spinning are: spinning speed of 2800 m / min, spinning temperature of 280°C, and drawing ratio of 2.

[0062] Example 4

[0063] A flame-retardant polyester fiber and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that an equal amount of montmorillonite-based flame retardant B is used instead of montmorillonite-based flame retardant A.

[0064] Example 5

[0065] A flame-retardant polyester fiber and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that an equal amount of montmorillonite-based flame retardant C is used instead of montmorillonite-based flame retardant A.

[0066] Example 6

[0067] A flame-retardant polyester fiber and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that the flame-retardant polyester masterbatch is obtained by granulating a montmorillonite-based flame retardant A and polyester powder, and the mass ratio of the two is 1:5.5.

[0068] Comparative Example 1

[0069] A flame-retardant polyester fiber and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that an equal amount of commercially available montmorillonite is used instead of montmorillonite-based flame retardant A.

[0070] Effect evaluation:

[0071] The polyester fibers prepared in Examples 1-6 and Comparative Example 1 were tested, and the specific results are shown in Table 1.

[0072] Performance testing:

[0073] (1) Limiting oxygen index: Tested in accordance with FZ / T 50017-2011 “Test method for flame retardancy of polyester fibers - Oxygen index method”;

[0074] (2) Droplet quantity: Referring to the description and test method of droplet in patent CN202411077402.1, the present invention adopts a UL1581 combustion tester to continuously burn the sample, collects the droplet at the bottom with water, and weighs and detects the droplet quantity.

[0075] Table 1

[0076] Serial number Limiting oxygen index / % Droplet amount / mg Example 1 32.4 35 Example 2 30.1 40 Example 3 32.6 34 Example 4 28.7 52 Example 5 28.9 54 Example 6 28.2 68 Comparative Example 1 27.8 85

[0077] The results in Table 1 show that the polyester fibers of Examples 1 to 3 have excellent flame retardancy and anti-dripping properties.

[0078] Compared with Example 1, when preparing the montmorillonite-based flame retardant, Example 4 changed the molar ratio of 3-aminophenylboric acid and 3,4-dihydroxybenzaldehyde, and the boric acid group and benzene ring structure were reduced. Example 5 changed the mass ratio of silanized montmorillonite and the reactant, and the amount of reactant grafting was reduced. Comparative Example 1 replaced the montmorillonite-based flame retardant A with commercially available montmorillonite, which had poor dispersibility. All of the above will weaken the flame retardancy and anti-melting droplet properties of the polyester fiber.

[0079] Compared with Example 1, Example 6 changes the mass ratio of montmorillonite-based flame retardant A and polyester powder in the flame-retardant polyester masterbatch. Obviously, the reduction of montmorillonite-based flame retardant A will weaken the flame retardancy and anti-dripping properties of the polyester fiber.

[0080] The above is only a preferred embodiment of the present invention and does not limit the present application in any form. Although the present application is disclosed as above with a preferred embodiment, it is not intended to limit the present application. Any technician familiar with this profession, without departing from the scope of the technical solution of the present application, makes some changes or modifications using the technical content disclosed above, which are equivalent to equivalent implementation cases. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution.

Claims

1. A flame retardant polyester fiber, characterized in that: The polyester fiber comprises the following raw materials in parts by weight: 50-70 parts of polyester chips, 6-10 parts of flame-retardant polyester masterbatch, and 1-2 parts of antioxidant; wherein the flame-retardant polyester masterbatch is obtained by granulating a montmorillonite-based flame retardant and polyester powder.

2. The flame-retardant polyester fiber according to claim 1, characterized in that: The preparation method of the montmorillonite-based flame retardant comprises the following steps: S1. The montmorillonite was washed, dried, added to a 2-4% volume concentration of aqueous phosphoric acid solution, stirred, filtered, washed, and dried to obtain acidified montmorillonite; S2. Mix the aminosilane coupling agent, methanol, and water, heat to 50-55°C, adjust the pH to 4-5.5, stir at constant temperature for 30-60 min, add the acidified montmorillonite obtained in step S1, heat to 55-65°C, react for 1-2 h, wash, centrifuge, repeat 2-3 times, and dry at 85-90°C to obtain silanized montmorillonite; S3. Add 3-aminophenylboronic acid and 3,4-dihydroxybenzaldehyde to a mixed solution of ethanol and water, stir and react at 35-50 ° C for 3-6 hours, protect from light throughout the reaction, and distill under reduced pressure until the mixed solution of ethanol and water remains 1 / 4-1 / 3, wash, and dry to obtain a reactant; S4. The silanized montmorillonite obtained in step S2, the reactant obtained in step S3, and ethanol are mixed, heated and stirred to react for 8-12 hours, filtered, and dried to obtain a montmorillonite-based flame retardant.

3. The flame-retardant polyester fiber according to claim 2, characterized in that: The aminosilane coupling agent in step S2 is 3-aminopropyl-triethoxysilane and / or N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane.

4. The flame-retardant polyester fiber according to claim 2, characterized in that: The molar ratio of 3-aminophenylboronic acid to 3,4-dihydroxybenzaldehyde in step S3 is (2.05-2.2):

1.

5. The flame-retardant polyester fiber according to claim 2, characterized in that: The mass ratio of the silanized montmorillonite to the reactant in step S4 is 1:(1-2).

6. The flame-retardant polyester fiber according to claim 1, characterized in that: The mass ratio of the montmorillonite-based flame retardant to the polyester powder is 1:(4-5).

7. The flame-retardant polyester fiber according to claim 1, characterized in that: The preparation method of the flame retardant polyester masterbatch comprises the following steps: The polyester powder is first dried at 120-130°C for 10-12 hours, and then the montmorillonite-based flame retardant and polyester powder are mixed and put into a twin-screw extruder for melt blending and extrusion granulation. The processing temperature of the twin-screw extruder is 250-260°C and the processing speed is 20-25r / min to obtain a flame-retardant polyester masterbatch.

8. The flame-retardant polyester fiber according to claim 1, characterized in that: The antioxidant is a hindered phenol antioxidant and / or a phosphite antioxidant.

9. A method for preparing the flame-retardant polyester fiber according to any one of claims 1 to 8, characterized in that: The following steps are included: Q1. Add flame-retardant polyester masterbatch, polyester chips, and antioxidant into a mixer and stir to obtain a mixture; Q2. The mixture obtained in step Q1 is added to a twin-screw extruder for extrusion granulation. The processing temperature of the twin-screw extruder is 250-260°C and the processing speed is 20-25r / min. After melt blending and extrusion granulation, melt spinning is performed, and after cooling, oiling, pre-stretching, winding, and stretching, a flame-retardant polyester fiber is obtained.

10. The method for preparing a flame-retardant polyester fiber according to claim 9, characterized in that: The process parameters of the melt spinning are: spinning speed of 2600-2800 m / min, spinning temperature of 270-280° C., and drawing ratio of 1.5-2 times.