A colored high-strength PET fiber and its preparation method

Abstract

This invention belongs to the field of synthetic fiber technology and relates to a colored high-strength PET fiber and its preparation method. The preparation method involves melt spinning a PET melt containing a colored high-strength modifier to obtain the colored high-strength PET fiber. The colored high-strength modifier has a linear molecular chain with PDI or NDI in the middle and aromatic rings at both ends. The melt spinning includes a drawing process. The colored high-strength PET fiber has a linear density deviation rate of 1-1.6%, a linear density coefficient of variation of 0.5-2%, a linear density of 8500-9000 dtex, a breaking elongation of 14.9-15.2%, a breaking elongation coefficient of variation of 4.5-5%, a breaking strength coefficient of variation of 2.1-2.5%, and color fastness to light (grade 8), color fastness to washing (grade 5), color fastness to water (grade 5), color fastness to rubbing (grade 5), and color fastness to perspiration (grade 5), thus achieving both high strength and high color fastness.

Description

Technical Field

[0001] This invention belongs to the field of synthetic fiber technology and relates to a colored high-strength PET fiber and its preparation method. Background Technology

[0002] High-strength fibers are lightweight yet possess superior tensile strength and toughness, effectively enhancing the strength of composite materials and making them more reliable under high pressure and impact. Furthermore, the wear resistance of high-strength fibers extends product lifespan and reduces maintenance costs, leading to their widespread application in various fields such as aerospace, automotive, sports equipment, protective gear, and construction. Currently, there are four commonly used methods for preparing high-strength fibers: (1) gel spinning and high-stretch fiber production process, which involves wet spinning a high-molecular-weight polyethylene solution into gel-like fibers and then drawing the fibers out at a high draw ratio; (2) liquid crystal spinning, which utilizes a liquid crystal solution of a rigid polymer in a semi-dry, semi-wet state to produce highly oriented crystals of the rigid polymer through a spinning head; (3) by altering the molecular chain structure of para-aromatic polyamide fibers, dissolving them in an organic solvent, and then spinning them in a semi-dry, semi-wet state; and (4) by melt spinning a semi-rigid polymer to achieve ultra-high strength fibers, a process specifically designed for processing aromatic polyesters.

[0003] Colored fibers have wide applications in anti-counterfeiting technology, safety warnings, and enhancing product aesthetics. Currently, there are two main methods for coloring colored fibers: (1) conventional fiber coloring, which is a dyeing method for PET fibers with high hydrophobicity and crystallinity. The key is to accelerate the diffusion rate of dye in the fiber; (2) pre-spinning solution coloring, which is a method of directly producing colored fibers by adding appropriate pigments or dyes during the production of chemical fibers. It is also known as pre-spinning coloring. Unlike conventional dyeing, this pre-spinning coloring method makes the colorant uniformly dispersed in the polymer. After spinning, the colorant is fixed in the fiber. The coloring process is a physical change.

[0004] PET fiber has advantages such as good fiber-forming properties, high strength, wear resistance, and aging resistance, and has been widely used in the manufacture of various textiles. PET fiber that combines colored and high strength has even more important application value.

[0005] Currently, research on PET fibers that simultaneously achieve both color and high strength is limited. The main approach involves adding color masterbatches to high-strength fibers or performing color spraying later to achieve color. However, this method has drawbacks: the added masterbatches can affect fiber strength, and the unique chemical structure of high-strength fibers can lead to poor compatibility with commonly used dyes, thus affecting colorfastness. For example, patent application CN109322006A discloses a colored high-strength polyethylene fiber, whose preparation method includes the following steps: preparation of spinning solution; preparation of high-strength polyethylene fiber; high-strength polyethylene fiber spraying modification; and ultraviolet light treatment. This preparation method achieves both color and high strength by performing color spraying after producing high-strength fibers. The high-strength and colored effects are achieved separately, leading to compatibility issues between the fiber and dyes, which affect colorfastness.

[0006] Therefore, given that existing PET fibers cannot simultaneously achieve both high color fastness and high strength, it is necessary to develop a PET fiber and its preparation method that can simultaneously achieve both high color fastness and high strength, in order to promote the further development of the PET industry. Summary of the Invention

[0007] The purpose of this invention is to solve the above-mentioned problems existing in the prior art and to provide a colored high-strength PET fiber and its preparation method.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A method for preparing colored high-strength PET fiber involves melt spinning a PET melt containing a colored high-strength modifier to obtain colored high-strength PET fiber. The colored high-strength modifier has a linear molecular chain with PDI (3,4,9,10-perylene diimide, CAS No. 81-33-4) or NDI (1,4,5,8-naphthalene diimide, CAS No. 5690-24-4) in the middle and aromatic rings at both ends. The melt spinning process includes a drawing step.

[0010] The principle of this invention is as follows: During the drawing process, due to the conjugated rigid structure of the perylene ring or naphthalene ring in the PDI or NDI structure of the colored high-strength modifier, and the conjugated structure of the aromatic rings (e.g., benzene ring, naphthalene ring, anthracene ring) attached to both ends of the PDI or NDI structure, under the action of the stress field, PDI and NDI are aligned along the orientation direction of the PET molecular chain. The large number of aromatic rings at both ends of the PDI or NDI structure can form stable π-π interactions with the benzene rings on the PET fiber, which strengthens the interaction between molecular chains in the microfibril structure of the fiber. At the same time, the aromatic rings participate in the crystallization of the microfibril crystallization region. Therefore, the colored high-strength modifier enhances the interaction between the interfaces in the fiber microfibril structure, which is beneficial to improving the fiber strength and the bonding strength between the fiber and the colored high-strength modifier. In addition, PDI and NDI themselves have bright colors and can be used as a source of color for colored fibers.

[0011] As a preferred technical solution:

[0012] The above-described method for preparing colored high-strength PET fibers uses a colored high-strength modifier as follows: Where n≥2.

[0013] In the above-described method for preparing colored high-strength PET fibers, the content of the colored high-strength modifier in the PET melt is 5-7 wt%.

[0014] The method for preparing colored high-strength PET fiber as described above involves a drafting ratio of 5-6 times, using four pairs of drafting rollers. The temperature of the first pair of drafting rollers is 140-150℃, and the spinning speed is 400-500 m / min. The temperature of the second pair of drafting rollers is 239-250℃, and the spinning speed is 1255-1600 m / min. The temperature of the third pair of drafting rollers is 246-250℃, and the spinning speed is 2000-2500 m / min. The temperature of the fourth pair of drafting rollers is 245-250℃, and the spinning speed is 2400-2500 m / min.

[0015] The preparation method of colored high-strength PET fiber as described above involves the following steps: first, the colored high-strength modifier is melt-blended with PET chips to obtain a masterbatch with a colored high-strength modifier concentration of 40-45 wt%; then, the masterbatch is melt-blended with PET chips.

[0016] The method for preparing colored high-strength PET fiber as described above involves melt blending masterbatch and PET chips using a twin-screw extruder. The temperatures of each zone of the twin-screw extruder are as follows: Zone 1: 271-277℃; Zone 2: 289-293℃; Zone 3: 286-293℃; Zone 4: 289-295℃; Zone 5: 292-295℃.

[0017] The process flow of melt spinning for preparing colored high-strength PET fiber as described above is: spinning → cooling → drawing → setting → winding.

[0018] The method for preparing colored high-strength PET fiber as described above involves spinning at a temperature of 303-305℃; cooling air temperature of 22-25℃, relative humidity of the air at 73-75%, and air velocity of 0.7-0.8m / s; setting temperature of 88-109℃; and winding speed of 4185-4200m / min.

[0019] The present invention also provides a colored high-strength PET fiber, which is prepared by the method for preparing a colored high-strength PET fiber as described in any of the preceding claims.

[0020] As a preferred technical solution:

[0021] The colored high-strength PET fiber described above has a linear density deviation rate of 1-1.6%, a linear density variation coefficient of 0.5-2%, a linear density of 8500-9000 dtex, a breaking elongation of 14.9-15.2%, a breaking elongation variation coefficient of 4.5-5%, a breaking strength variation coefficient of 2.1-2.5%, a light fastness grade of 8, a soap fastness grade of 5, a water fastness grade of 5, a rubbing fastness grade of 5, and a perspiration fastness grade of 5.

[0022] Beneficial effects:

[0023] (1) The preparation method of the present invention uses PDI or NDI with aromatic rings (e.g., benzene ring, naphthalene ring, anthracene ring) attached to both ends as a colored high-strength modifier, which strengthens the interaction between molecular chains in the microfiber structure of the fiber. At the same time, these aromatic rings participate in the crystallization of the microfiber crystallization region, which enhances the interaction between the interfaces in the microfiber structure of the fiber. This is beneficial to improve the fiber strength and the bonding strength between the fiber and the colored high-strength modifier. Moreover, the colored high-strength modifier itself has a bright color, which serves as the color source for the colored fiber, thus achieving both high fiber strength and high color fastness.

[0024] (2) The preparation method of the present invention adds a single colored high-strength modifier, the reaction system is uniformly dispersed, avoids complex additives and cumbersome process flow, and improves preparation efficiency. Attached Figure Description

[0025] Figure 1 These are schematic diagrams of the structure of the colored high-strength PET fibers in Examples 1-4 of this invention;

[0026] Figure 2 It is the colored high-strength modifier of Example 1 of this invention.1 HNMR spectrum;

[0027] Figure 3 This is the colored high-strength modifier of Example 2 of the present invention. 1 HNMR spectrum;

[0028] Figure 4 This is the colored high-strength modifier of Example 3 of the present invention. 1 HNMR spectrum;

[0029] Figure 5 This is the colored high-strength modifier of Example 4 of the present invention. 1 HNMR spectrum. Detailed Implementation

[0030] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the contents of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the claims of this application.

[0031] The following are the test methods for the relevant performance indicators in each embodiment and comparative example:

[0032] (1) Linear density deviation rate: Tested in accordance with national standard GB / T4743-2009.

[0033] (2) Linear density variation coefficient: Tested according to method B of national standard GB / T14343-2003.

[0034] (3) Linear density: Tested in accordance with national standard GB / T16604-2017.

[0035] (4) Elongation at break: Tested in accordance with national standard GB / T 3923.1-2013.

[0036] (5) Coefficient of variation of elongation at break: Tested in accordance with national standard GB / T 3923.1-2013.

[0037] (6) Coefficient of variation of fracture strength: Tested in accordance with national standard GB / T14344-2008.

[0038] (7) Color fastness to light: Tested in accordance with national standard GB / T8427-2008.

[0039] (8) Color fastness to soap washing: Tested in accordance with national standard GB / T3921-2008.

[0040] (9) Water fastness: Tested in accordance with national standard GB / T5713-2013.

[0041] (10) Color fastness to rubbing: Tested in accordance with national standard GB / T3920-2008.

[0042] (11) Color fastness to perspiration: Tested in accordance with national standard GB / T3922-2013.

[0043] Example 1

[0044] A method for preparing colored high-strength PET fiber, the specific steps of which are as follows:

[0045] (1) Raw material preparation;

[0046] PTCDA (3,4,9,10-perylenetetracarboxylic dianhydride): The structure is shown in formula (Ⅰ);

[0047]

[0048] Long-chain aniline: The structure is shown in formula (II), where n = 2;

[0049]

[0050] Imidazole;

[0051] N2;

[0052] Deionized water;

[0053] Anhydrous ethanol;

[0054] PET chips: Fiber-grade semi-dull PET chips, manufactured by Yizheng Chemical Fiber, grade TFW100;

[0055] (2) Synthetic colored high-strength modifier

[0056] 5.1 mmol PTCDA, 10.2 mmol long-chain aniline, and 88.1 mmol imidazole were added sequentially to a three-necked flask. The reaction was carried out at 140 °C for 2 h under N2 protection. After the reaction, the mixture was cooled to 25 °C, and deionized water was added to the flask. The imidazole was dispersed by stirring and then filtered through a separatory funnel. The filter cake was washed three times with deionized water and anhydrous ethanol, and dried to obtain a red powder product, which is the colored high-strength modifier. This colored high-strength modifier is a PDI powder with a benzene ring. Its purity was determined to be 86% according to the national standard GB / T15000.3-2001. The 1H NMR spectrum is shown below. Figure 2 As shown, δ = 4.05-4.25 represents the chemical shift of H at the CH2 junction connected to N, δ = 8.58-8.72 represents the chemical shift of H on the perylene ring, and δ = 7.1-7.3 represents the chemical shift of H on the side chain benzene ring.

[0057] The reaction between PTCDA and long-chain aniline is shown in formula (III);

[0058]

[0059] (3) Preparation of masterbatch;

[0060] A colored high-strength modifier was melt-blended with PET chips to obtain a masterbatch with a concentration of 45 wt%.

[0061] (4) Melt spinning;

[0062] (4.1) Spinning: First, the masterbatch and PET chips are melt-blended using a twin-screw extruder to obtain PET melt. The content of colored high-strength modifier in the PET melt is 7wt%. The temperatures of each zone of the twin-screw extruder are: Zone 1 temperature 275℃, Zone 2 temperature 290℃, Zone 3 temperature 286℃, Zone 4 temperature 289℃, Zone 5 temperature 294℃. Then, electrospinning is performed at a temperature of 304℃.

[0063] (4.2) Cooling: The air temperature during cooling is 23℃, the relative humidity of the air is 75%, and the air speed is 0.7m / s;

[0064] (4.3) Drafting: The drafting ratio is 6 times, and four pairs of drafting rollers are used for drafting; the temperature of the first pair of drafting rollers is 145℃ and the spinning speed is 400m / min; the temperature of the second pair of drafting rollers is 246℃ and the spinning speed is 1600m / min; the temperature of the third pair of drafting rollers is 250℃ and the spinning speed is 2000m / min; the temperature of the fourth pair of drafting rollers is 250℃ and the spinning speed is 2400m / min.

[0065] (4.4) Shaping: The shaping temperature is 109℃;

[0066] (4.5) Winding: The winding speed is 4190m / min, which yields colored high-strength PET fibers.

[0067] The final colored high-strength PET fiber has a linear density deviation rate of 1.5%, a linear density variation coefficient of 0.6%, a linear density of 8900 dtex, a breaking elongation of 15%, a breaking elongation variation coefficient of 4.5%, a breaking strength variation coefficient of 2.3%, a light fastness grade of 8, a soap fastness grade of 5, a water fastness grade of 5, a rubbing fastness grade of 5, and a perspiration fastness grade of 5.

[0068] Comparative Example 1

[0069] A method for preparing PET fiber is basically the same as in Example 1, except that PTCDA and long-chain aniline are used instead of the colored high-strength modifier, and the amount of PTCDA and long-chain aniline used is the same as in Example 1.

[0070] The final PET fiber has a linear density deviation rate of 4%, a linear density variation coefficient of 8%, a breaking elongation of 10%, a breaking elongation variation coefficient of 9%, a breaking strength variation coefficient of 7%, a light fastness grade of 4, a soap fastness grade of 1, a water fastness grade of 2, a rubbing fastness grade of 1, and a perspiration fastness grade of 2.

[0071] Example 2

[0072] A method for preparing colored high-strength PET fiber, the specific steps of which are as follows:

[0073] (1) Raw material preparation;

[0074] PTCDA: The structure is shown in equation (Ⅰ);

[0075] Long-chain naphthylamine: The structure is shown in formula (Ⅳ), where n=3;

[0076]

[0077] Imidazole;

[0078] N2;

[0079] Deionized water;

[0080] Anhydrous ethanol;

[0081] PET chips: Fiber-grade semi-dull PET chips, manufactured by Yizheng Chemical Fiber, grade TFW100;

[0082] (2) Synthesize colored high-strength modifiers;

[0083] In a three-necked flask, 5.1 mmol PTCDA, 10.2 mmol long-chain naphthylamine, and 88.1 mmol imidazole were added sequentially. The mixture was reacted at 140 °C for 2 h under N2 protection. After the reaction, the mixture was cooled to room temperature, and deionized water was added. The imidazole was dispersed by stirring and then filtered through a separatory funnel. The filter cake was washed three times with deionized water and anhydrous ethanol, and dried to obtain a red powder product, which is the colored high-strength modifier. This colored high-strength modifier is a PDI powder containing a naphthalene ring. Its purity was determined to be 82% according to the national standard GB / T 15000.3-2001. The 1H NMR spectrum is shown below. Figure 3 As shown, δ = 4.05-4.25 represents the chemical shift of H at the CH2 junction connected to N, δ = 8.53-8.68 represents the chemical shift of H on the perylene ring, and δ = 7.2-7.9 represents the chemical shift of H on the side chain naphthalene ring.

[0084] The reaction of PTCDA with long-chain naphthylamine is shown in formula (V);

[0085]

[0086] (3) Preparation of masterbatch;

[0087] A colored high-strength modifier was melt-blended with PET chips to obtain a masterbatch with a concentration of 43 wt%.

[0088] (4) Melt spinning;

[0089] (4.1) Spinning: First, the masterbatch and PET chips are melt-blended using a twin-screw extruder to obtain PET melt. The content of colored high-strength modifier in the PET melt is 6wt%. The temperatures of each zone of the twin-screw extruder are: Zone 1 temperature 277℃, Zone 2 temperature 293℃, Zone 3 temperature 289℃, Zone 4 temperature 295℃, Zone 5 temperature 295℃. Then, electrospinning is performed at a temperature of 305℃.

[0090] (4.2) Cooling: The air temperature during cooling is 22℃, the relative humidity of the air is 74%, and the air speed is 0.8m / s;

[0091] (4.3) Drafting: The drafting ratio is 6 times, and four pairs of drafting rollers are used for drafting; the temperature of the first pair of drafting rollers is 140℃ and the spinning speed is 400m / min; the temperature of the second pair of drafting rollers is 250℃ and the spinning speed is 1600m / min; the temperature of the third pair of drafting rollers is 246℃ and the spinning speed is 2000m / min; the temperature of the fourth pair of drafting rollers is 245℃ and the spinning speed is 2400m / min.

[0092] (4.4) Shaping: The shaping temperature is 99℃;

[0093] (4.5) Winding: The winding speed is 4200m / min, which yields colored high-strength PET fibers.

[0094] The final colored high-strength PET fiber has a linear density deviation rate of 1%, a linear density variation coefficient of 0.5%, a linear density of 8700 dtex, a breaking elongation of 15.2%, a breaking elongation variation coefficient of 4.6%, a breaking strength variation coefficient of 2.2%, a light fastness grade of 8, a soap fastness grade of 5, a water fastness grade of 5, a rubbing fastness grade of 5, and a perspiration fastness grade of 5.

[0095] Comparative Example 2

[0096] A method for preparing PET fiber is basically the same as in Example 2, except that PTCDA and long-chain naphthylamine are used instead of the colored high-strength modifier, and the amount of PTCDA and long-chain naphthylamine used is the same as in Example 2.

[0097] The final PET fiber had a linear density deviation rate of 4.1%, a linear density variation coefficient of 8%, a breaking elongation of 10%, a breaking elongation variation coefficient of 8.9%, a breaking strength variation coefficient of 7%, a light fastness grade of 4, a soap fastness grade of 1, a water fastness grade of 2, a rubbing fastness grade of 1, and a perspiration fastness grade of 2.

[0098] Example 3

[0099] A method for preparing colored high-strength PET fiber, the specific steps of which are as follows:

[0100] (1) Raw material preparation;

[0101] PTCDA: The structure is shown in equation (Ⅰ);

[0102] Long-chain anthracene: The structure is shown in formula (VI), where n = 4;

[0103]

[0104] Imidazole;

[0105] N2;

[0106] Deionized water;

[0107] Anhydrous ethanol;

[0108] PET chips: Fiber-grade semi-dull PET chips, manufactured by Yizheng Chemical Fiber, grade TFW100;

[0109] (2) Synthesize colored high-strength modifiers;

[0110] In a three-necked flask, 5.1 mmol PTCDA, 10.2 mmol long-chain anthraquinone, and 88.1 mmol imidazole were added sequentially. The mixture was reacted at 140 °C for 2 h under N2 protection. After the reaction, the mixture was cooled to room temperature, and deionized water was added. The imidazole was dispersed by stirring and then filtered through a separatory funnel. The filter cake was washed three times with deionized water and anhydrous ethanol, and dried to obtain a red powder product, which is the colored high-strength modifier. This colored high-strength modifier is an anthracene-containing PDI powder. Its purity was determined to be 82% according to the national standard GB / T 15000.3-2001. The 1H NMR spectrum is shown below. Figure 4 As shown, δ = 4.05-4.23 represents the chemical shift of H at the CH2 junction connected to N, δ = 8.5-8.67 represents the chemical shift of H on the perylene ring, and δ = 7.3-8.5 represents the chemical shift of H on the anthracene ring of the side chain.

[0111] The reaction between PTCDA and long-chain anthracene is shown in formula (VII);

[0112]

[0113] (3) Preparation of masterbatch;

[0114] A colored high-strength modifier was melt-blended with PET chips to obtain a masterbatch with a concentration of 41 wt%.

[0115] (4) Melt spinning;

[0116] (4.1) Spinning: First, the masterbatch and PET chips are melt-blended using a twin-screw extruder to obtain PET melt. The content of colored high-strength modifier in the PET melt is 5wt%. The temperatures of each zone of the twin-screw extruder are: Zone 1 temperature 273℃, Zone 2 temperature 289℃, Zone 3 temperature 293℃, Zone 4 temperature 294℃, Zone 5 temperature 293℃. Then, electrospinning is performed at a temperature of 303℃.

[0117] (4.2) Cooling: The air temperature during cooling is 25℃, the relative humidity of the air is 73%, and the air speed is 0.8m / s;

[0118] (4.3) Drafting: The drafting ratio is 5 times, and four pairs of drafting rollers are used; the temperature of the first pair of drafting rollers is 148℃ and the spinning speed is 500m / min; the temperature of the second pair of drafting rollers is 243℃ and the spinning speed is 1255m / min; the temperature of the third pair of drafting rollers is 247℃ and the spinning speed is 2500m / min; the temperature of the fourth pair of drafting rollers is 246℃ and the spinning speed is 2500m / min.

[0119] (4.4) Shaping: The shaping temperature is 102℃;

[0120] (4.5) Winding: The winding speed is 4185m / min, which yields colored high-strength PET fibers.

[0121] The final colored high-strength PET fiber has a linear density deviation rate of 1.2%, a linear density variation coefficient of 2%, a linear density of 9000 dtex, a breaking elongation of 14.9%, a breaking elongation variation coefficient of 4.7%, a breaking strength variation coefficient of 2.1%, a light fastness grade of 8, a soap fastness grade of 5, a water fastness grade of 5, a rubbing fastness grade of 5, and a perspiration fastness grade of 5.

[0122] Comparative Example 3

[0123] A method for preparing PET fiber is basically the same as in Example 3, except that PTCDA and long-chain anthracene are used instead of the colored high-strength modifier, and the amount of PTCDA and long-chain anthracene is the same as in Example 3.

[0124] The final PET fiber had a linear density deviation rate of 4.1%, a linear density coefficient of variation of 8%, a breaking elongation of 10%, a breaking elongation coefficient of variation of 8.7%, a breaking strength coefficient of variation of 7%, a light fastness of grade 4, a soap fastness of grade 1, a water fastness of grade 2, a rubbing fastness of grade 1, and a perspiration fastness of grade 2.

[0125] Example 4

[0126] A method for preparing colored high-strength PET fiber, the specific steps of which are as follows:

[0127] (1) Raw material preparation;

[0128] NTCDA (1,4,5,8-naphthalenetetracarboxylic anhydride): The structure is shown in formula (VIII);

[0129]

[0130] Long-chain aniline: The structure is shown in formula (II), where n = 5;

[0131] Imidazole:

[0132] N2;

[0133] Deionized water;

[0134] Anhydrous ethanol;

[0135] PET chips: Fiber-grade semi-dull PET chips, manufactured by Yizheng Chemical Fiber, grade TFW100;

[0136] (2) Synthesize colored high-strength modifiers;

[0137] In a three-necked flask, 7.5 mmol NTCDA, 10.2 mmol long-chain aniline, and 88.1 mmol imidazole were added sequentially. The mixture was reacted at 140 °C for 2 h under N2 protection. After the reaction, the mixture was cooled to room temperature. Deionized water was added to the flask, and the imidazole was dispersed by stirring. The mixture was then filtered through a separatory funnel. The filter cake was washed three times with deionized water and anhydrous ethanol, and dried to obtain a yellow powder product, which is the colored high-strength modifier. This colored high-strength modifier is an NDI powder containing a benzene ring. According to the national standard GB / T 15000.3-2001, its purity is 81%. The 1H NMR spectrum is as follows: Figure 5 As shown, δ = 4.35-4.4 represents the chemical shift of H at the CH2 site connected to N, δ = 8.75-8.8 represents the chemical shift of H on the naphthalene ring, and δ = 7.1-7.3 represents the chemical shift of H on the side chain benzene ring.

[0138] The reaction of NTCDA with long-chain aniline is shown in formula (IX);

[0139]

[0140] (3) Preparation of masterbatch;

[0141] A colored high-strength modifier was melt-blended with PET chips to obtain a masterbatch with a concentration of 40 wt%.

[0142] (4) Melt spinning;

[0143] (4.1) Spinning: First, the masterbatch and PET chips are melt-blended using a twin-screw extruder to obtain PET melt. The content of colored high-strength modifier in the PET melt is 5wt%. The temperatures of each zone of the twin-screw extruder are: Zone 1 temperature 271℃, Zone 2 temperature 292℃, Zone 3 temperature 292℃, Zone 4 temperature 294℃, Zone 5 temperature 292℃. Then, electrospinning is performed at a temperature of 304℃.

[0144] (4.2) Cooling: The air temperature during cooling is 25℃, the relative humidity of the air is 74%, and the wind speed is 0.7m / s;

[0145] (4.3) Drafting: The drafting ratio is 6 times, and four pairs of drafting rollers are used; the temperature of the first pair of drafting rollers is 150℃ and the spinning speed is 400m / min; the temperature of the second pair of drafting rollers is 239℃ and the spinning speed is 1600m / min; the temperature of the third pair of drafting rollers is 250℃ and the spinning speed is 2000m / min; the temperature of the fourth pair of drafting rollers is 248℃ and the spinning speed is 2400m / min.

[0146] (4.4) Shaping: The shaping temperature is 88℃;

[0147] (4.5) Winding: The winding speed is 4189 m / min, which yields colored high-strength PET fibers.

[0148] The final colored high-strength PET fiber has a linear density deviation rate of 1.6%, a linear density variation coefficient of 1.3%, a linear density of 8500 dtex, a breaking elongation of 15.1%, a breaking elongation variation coefficient of 5%, a breaking strength variation coefficient of 2.5%, a light fastness grade of 8, a soap fastness grade of 5, a water fastness grade of 5, a rubbing fastness grade of 5, and a perspiration fastness grade of 5.

[0149] Comparative Example 4

[0150] A method for preparing PET fiber is basically the same as in Example 4, except that NTCDA and long-chain aniline are used instead of the colored high-strength modifier, and the amount of NTCDA and long-chain aniline used is the same as in Example 4.

[0151] The final PET fiber had a linear density deviation rate of 4.1%, a linear density variation coefficient of 8%, a breaking elongation of 10%, a breaking elongation variation coefficient of 8.6%, a breaking strength variation coefficient of 7%, a light fastness grade of 3, a soap fastness grade of 1, a water fastness grade of 2, a rubbing fastness grade of 1, and a perspiration fastness grade of 2.

[0152] In summary, comparing Examples 1-4 with Comparative Examples 1-4, the linear density deviation rate, linear density coefficient of variation, elongation at break coefficient of variation, and tensile strength coefficient of variation of the PET fibers finally obtained in Examples 1-4 were significantly lower than those of the PET fibers finally obtained in Comparative Examples 1-4. Furthermore, the light fastness, soaping fastness, water fastness, rubbing fastness, and perspiration fastness of the PET fibers finally obtained in Examples 1-4 were significantly higher than those of the PET fibers finally obtained in Comparative Examples 1-4. This is because Examples 1-4... During the fiber drawing process, the perylene or naphthalene rings of the PDI or NDI structure in the aforementioned colored high-strength modifiers have a conjugated rigid structure, and the aromatic rings (e.g., benzene, naphthalene, anthracene) attached to both ends of the PDI or NDI also have a conjugated structure. Under the action of a stress field, the PDI aligns along the orientation direction of the PET molecular chain. These aromatic rings can form stable π-π interactions with the benzene rings on the PET fiber, strengthening the intermolecular chain interactions in the fiber microfiber structure and increasing the fiber strength; at the same time, these aromatic rings participate in the crystallization of the microfiber crystalline region (e.g., Figure 1 As shown in the figure, the above-mentioned colored high-strength modifier enhances the interaction between interfaces in the fiber microfiber structure, which is beneficial to improving fiber strength. The strong interaction between dye and fiber also gives it high color fastness.

Claims

1. A method for preparing colored high-strength PET fibers, characterized in that, The PET melt containing a colored high-strength modifier is melt-spun to obtain colored high-strength PET fiber. The colored high-strength modifier has a linear molecular chain with PDI or NDI in the middle and aromatic rings at both ends. The melt spinning process includes a drawing process. Colored high-strength modifier is , , or , where 2≤n≤5.

2. The method for preparing colored high-strength PET fiber according to claim 1, characterized in that, In PET melt containing colored high-strength modifiers, the content of colored high-strength modifiers is 5-7 wt%.

3. The method for preparing colored high-strength PET fiber according to claim 1, characterized in that, The drafting ratio is 5-6 times, and four pairs of drafting rollers are used for drafting. The temperature of the first pair of drafting rollers is 140-150℃, and the spinning speed is 400-500m / min. The temperature of the second pair of drafting rollers is 239-250℃, and the spinning speed is 1255-1600m / min. The temperature of the third pair of drafting rollers is 246-250℃, and the spinning speed is 2000-2500m / min. The temperature of the fourth pair of drafting rollers is 245-250℃, and the spinning speed is 2400-2500m / min.

4. The method for preparing colored high-strength PET fiber according to claim 1, characterized in that, The preparation process of PET melt containing colored high-strength modifier is as follows: First, the colored high-strength modifier is melt-blended with PET chips to obtain a masterbatch with a colored high-strength modifier concentration of 40-45wt%, and then the masterbatch is melt-blended with PET chips.

5. The method for preparing colored high-strength PET fiber according to claim 4, characterized in that, The masterbatch and PET chips are melt-blended using a twin-screw extruder. The temperatures of each zone of the twin-screw extruder are as follows: Zone 1: 271-277℃, Zone 2: 289-293℃, Zone 3: 286-293℃, Zone 4: 289-295℃, and Zone 5: 292-295℃.

6. The method for preparing colored high-strength PET fiber according to claim 1, characterized in that, The process flow of melt spinning is as follows: spinning → cooling → drawing → setting → winding.

7. The method for preparing colored high-strength PET fiber according to claim 6, characterized in that, The spinning temperature is 303-305℃; the cooling air temperature is 22-25℃, the relative humidity is 73-75%, and the air speed is 0.7-0.8m / s; the setting temperature is 88-109℃; and the winding speed is 4185-4200m / min.

8. A colored high-strength PET fiber, characterized in that, It is prepared by the method for preparing colored high-strength PET fiber as described in any one of claims 1 to 7.

9. A colored high-strength PET fiber according to claim 8, characterized in that, The linear density deviation rate of colored high-strength PET fiber is 1-1.6%, the coefficient of variation of linear density is 0.5-2%, the linear density is 8500-9000 dtex, the elongation at break is 14.9-15.2%, the coefficient of variation of elongation at break is 4.5-5%, the coefficient of variation of tensile strength is 2.1-2.5%, the color fastness to light is grade 8, the color fastness to soaping is grade 5, the color fastness to water is grade 5, the color fastness to rubbing is grade 5, and the color fastness to perspiration is grade 5.

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