Photochromic polyester fiber and preparation method thereof

Abstract

The invention relates to a photochromic polyester fiber and a preparation method thereof, the photochromic polyester fiber comprises a core layer and a skin layer, and the skin-core ratio is (20-80): (80-20); the core layer is prepared from the following raw materials in percentage by weight: 1 to 10 percent of photochromic polyester master batch and the balance of low-melting-point polyester chips; the photochromic polyester master batch is prepared from the following raw materials: photochromic powder, a titanate coupling agent, low-melting-point polyester powder, diatomite and aluminum nitride. The low-melting-point polyester material can reduce the damage of high temperature to the structure of the photochromic material, and the conventional polyester chips in the skin layer can further protect the photochromic material of the core layer, so that the service life of the photochromic material is prolonged, and the prepared photochromic polyester fiber has a good photochromic effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polyester fiber preparation, in particular to a photochromic polyester fiber and a preparation method thereof. BACKGROUND

[0002] In recent years, the demand for wearable electronic devices and adaptive materials has grown significantly, and smart materials with dynamic optical properties have attracted much attention. Photoresponsive color-changing fibers can undergo reversible color transition under external light stimulation, and have significant application value in military camouflage, biosensing and interactive textiles.

[0003] Photochromic systems generally include two types of intrinsic photoresponsive substances and functional composite materials. Typical photochromic substances in intrinsic materials include spiropyran derivatives, spirooxazine compounds, diarylethene substances, azobenzene molecular systems, transition metal oxides and polyoxometalates. Composite systems rely on the introduction of nano-structured units or polymer matrices to improve photoresponsive properties.

[0004] Because the processing temperature of conventional polyester is 265-295℃, photochromic materials lose their color-changing properties under high temperature conditions, so the performance of polyester fibers with photochromic function is poor. SUMMARY

[0005] In view of this, the present application provides a photochromic polyester fiber and a preparation method thereof to solve the above problems.

[0006] To achieve the above object, the technical scheme adopted by the present application is as follows:

[0007] In a first aspect, the present application provides a photochromic polyester fiber, which comprises a core layer and a skin layer, and the skin-to-core ratio is 20-80:80-20.

[0008] The raw materials of the core layer include 1%-10% of photochromic polyester masterbatch and the balance of low-melting-point polyester chips by weight percentage.

[0009] The raw materials of the photochromic polyester masterbatch include photochromic powder, titanate coupling agent, low-melting-point polyester powder, diatomite and aluminum nitride. The weight ratio of the photochromic powder, titanate coupling agent and low-melting-point polyester powder is 10-20:1-2:80-90. The addition amount of diatomite is 8%-12% and the addition amount of aluminum nitride is 15%-20% based on the mass of low-melting-point polyester powder.

[0010] The raw material of the skin layer is conventional polyester chips.

[0011] Preferably, the average particle size of the diatomite is 500-600nm, and the average particle size of the aluminum nitride is 300nm-500nm.

[0012] Preferably, the preparation method of the photochromic polyester masterbatch comprises the following steps:

[0013] (1) The low-melting-point polyester chip is crushed after deep cooling treatment to obtain the low-melting-point polyester powder;

[0014] (2) The photochromic powder, titanate coupling agent, low-melting-point polyester powder, diatomite and aluminum nitride are mixed according to the formula amount to obtain a mixed powder;

[0015] (3) The mixed powder is granulated and extruded by a single-screw extruder to obtain the photochromic polyester masterbatch.

[0016] Further preferably, in step (1), the temperature of the deep cooling treatment is-120 to-50℃, and the time is 8 to 12 min; in step (2), the temperature of the mixing is 85 to 95℃, the rotation speed is 300 to 500 rpm, and the time is 30 to 60 min.

[0017] Further preferably, in step (1), the melting point of the low-melting-point polyester chip is 180 to 220℃, and the average particle size of the crushed low-melting-point polyester powder is 100 to 300 mesh; in step (2), the average particle size of the photochromic powder is 400 to 600 nm.

[0018] Further preferably, the mixed powder is granulated and extruded by a single-screw extruder to obtain the photochromic polyester masterbatch, and the temperature partition of the single-screw extruder is set as one zone of 185℃, two zones of 195℃, three zones of 195℃, four zones of 200℃, and five zones of 200℃, and the melt is prepared into the photochromic polyester masterbatch by means of a water cooling granulation system with water temperature of 25±2℃.

[0019] Further preferably, the photochromic powder is one or more of spiro compound, diaryl ethylene and azobenzene, the spiro compound is spiropyran and / or spirooxazine; and the titanate coupling agent is isopropyl titanate and / or tetrabutyl titanate.

[0020] More preferably, the substituents of the spiropyran and spirooxazine contain phenyl and ester groups.

[0021] More preferably, the titanate coupling agent is isopropyl titanate and tetrabutyl titanate with a mass ratio of 1:0.4-0.7.

[0022] In a second aspect, the present application provides a preparation method of the photochromic polyester fiber of the first aspect, comprising the following steps: feeding the core layer raw material and the skin layer raw material into a screw extruder respectively for melting, feeding the core layer melt and the skin layer melt into a double-component spinning assembly through a metering pump, forming a fiber bundle after the melt is sprayed out of the spinning assembly, and finally winding to form the photochromic polyester fiber after side-blowing cooling, oiling, hot roller drafting, network interlacing and the like.

[0023] Preferably, the melting temperature of the core layer raw material is 195-245 DEG C, the melting temperature of the skin layer raw material is 265-295 DEG C, and the winding forming rate is 3500-5500 m / min.

[0024] Preferably, the spinning assembly comprises a spinning assembly, the length-diameter ratio of the spinning plate in the spinning assembly is 2.5, and the upper layer filter screen of the double-layer circular filter screen in the spinning assembly has a mesh number of 200 meshes, and the lower layer filter screen has a mesh number of 50 meshes.

[0025] Preferably, the temperature of the side-blowing cooling is 20-30 DEG C, and the humidity is 65%-70%.

[0026] Preferably, the oiling adopts oil wheel oiling, the oil agent used is a polyester fiber special oil agent, and the oiling amount is 0.6%-0.9%.

[0027] Preferably, the temperature of the hot roller drafting is 100-140 DEG C, and the drafting ratio is 1.3-1.7.

[0028] Preferably, the network interlacing adopts an air network nozzle to make each filament in the fiber bundle entangle.

[0029] Compared with the prior art, the present application has the following beneficial effects:

[0030] 1) The present application selects low-melting-point polyester chips as the core layer matrix, which can reduce the processing temperature, weaken the damage of high temperature to the structure of the photochromic material, and make the prepared polyester fiber have good photochromic effect.

[0031] 2) The present application processes the low-melting-point polyester chips through deep cooling and crushing, and uses the low-melting-point polyester chips, the photochromic powder and the titanate coupling agent as the raw materials of the photochromic polyester master batch in the core layer, which improves the interface bonding strength of the photochromic powder and the low-melting-point polyester powder and reduces the risk of core layer fracture in the spinning process.

[0032] 3) The addition of diatomite and aluminum nitride in the preparation of the photochromic polyester master batch can further improve the mechanical properties and air permeability of the photochromic polyester fiber.

[0033] 4) The complex structure design of the skin layer and the core layer effectively balances the functionality and mechanical properties. The skin layer and the core layer melt are metered by metering pumps and then enter the bi-component spinning assembly. After being extruded by the spinning assembly, the fiber is formed. By controlling the proportion of the skin layer and the core layer, the balance between the photochromic function and the physical properties of the fiber is adjusted, so that the prepared polyester fiber has good photochromic effect, and the mechanical property index meets the standard of polyester filament.

[0034] 5) Through the optimization of the skin-core composite spinning process, the temperature of the skin layer is controlled at 265-295℃, and the temperature of the core layer is controlled at 195-245℃. This not only solves the phenomenon of melt rupture or skin layer cracking caused by different steps or non-coordination of the skin-core component extrusion expansion during the spinning process, but also avoids the degradation and functional loss of the photochromic powder.

[0035] 6) The present application solves the adverse spinning phenomena such as uneven fiber thickness, skin layer cracking, and skin-core separation caused by the deformation of the core layer containing low-melting-point polyester material and the skin layer containing conventional polyester material under the action of high shear rate extrusion and high nozzle stretching ratio by optimizing the length-diameter ratio of the spinneret plate in the spinning assembly and the mesh number of the filter screen, and controlling the melting temperature of the skin layer and the core layer. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 The photochromic polyester fiber prepared in Example 1 is irradiated by a UV lamp for 180s, and the color development picture of the photochromic polyester fiber.

[0037] Figure 2 The photochromic polyester fiber prepared in Example 1 is irradiated by a UV lamp for 180s, and the color development picture of the photochromic polyester fiber is taken after leaving the light source for 180s. DETAILED DESCRIPTION

[0038] In order to better illustrate the purpose, technical scheme and advantages of the present application, the present application will be further described below in combination with specific examples and comparative examples, the purpose of which is to understand the content of the present application in detail, rather than to limit the present application. All other examples obtained by those of ordinary skill in the art without creative labor fall within the protection scope of the present application. The experimental reagents and instruments involved in the implementation of the present application are common ordinary reagents and instruments unless otherwise specified.

[0039] Low-melting-point polyester chips: PET low-melting-point polyester chips with a melting point of 180℃, purchased from Tongkun Group Co., Ltd.; (bright low-melting-point chips, first-class product)

[0040] Conventional polyester chips: PET conventional polyester chips with a melting point of 260℃, purchased from Tongkun Group Co., Ltd.; (bright polyester chips, first-class product)

[0041] Photochromic powder: di-arylethene, average particle size 500 nm, purchased from Fujian Mingkai Chemical Co., Ltd.;

[0042] Diatomite: average particle size 550 nm, purchased from Guangdong Yuanning New Material Co., Ltd.;

[0043] Aluminum nitride: average particle size 400 nm, purchased from Shanghai Xuantian New Material Technology Co., Ltd.

[0044] Example 1

[0045] A photochromic polyester fiber, comprising a core layer and a sheath layer, the sheath-to-core ratio being 20:80; the raw materials of the core layer include 5% photochromic polyester masterbatch and the balance of low-melting-point polyester chips by weight percentage; the raw materials of the sheath layer are conventional polyester chips;

[0046] The raw materials of the photochromic polyester masterbatch include photochromic powder, titanate coupling agent, low-melting-point polyester powder, diatomite and aluminum nitride; wherein the weight ratio of the photochromic powder, the titanate coupling agent and the low-melting-point polyester powder is 15:1.5:83.5; the addition amount of diatomite is 10% and the addition amount of aluminum nitride is 18% according to the mass of low-melting-point polyester powder; the titanate coupling agent is isopropyl titanate and tetrabutyl titanate with a mass ratio of 1:0.5;

[0047] The preparation method of the photochromic polyester masterbatch includes the following steps:

[0048] (1) The low-melting-point polyester chips are cryogenically treated at -100℃ for 10 min, then crushed, sieved and obtained as low-melting-point polyester powder with an average particle size of 200 mesh;

[0049] (2) The photochromic powder, the titanate coupling agent, the low-melting-point polyester powder, the diatomite and the aluminum nitride are mixed according to the formula amount, stirred at 90℃ and 400 rpm for 40 min to obtain a mixed powder;

[0050] (3) The mixed powder is added into a single-screw extruder, and the temperature partition is set as one zone at 185℃, two zones at 195℃, three zones at 195℃, four zones at 200℃ and five zones at 200℃, and the melt is cut into particles by means of a water cooling granulation system with water temperature at 25±2℃ to prepare the photochromic polyester masterbatch.

[0051] The preparation method of the photochromic polyester fiber, comprising the following steps:

[0052] The core layer raw material and the skin layer raw material are respectively fed into a screw extruder for melting, the core layer melt and the skin layer melt are metered by a metering pump and then enter a two-component spinning assembly, are sprayed out by the spinning assembly to form a yarn after being compounded, and are cooled by side blowing, are gathered and oiled, are drawn by a hot roller, are interlaced by a network, and are finally wound to form a shape to obtain the photochromic polyester fiber;

[0053] The melting temperature of the core layer raw material is 210℃, the melting temperature of the skin layer raw material is 280℃, and the winding forming rate is 4500m / min.

[0054] The spinning assembly comprises a spinning assembly, the aspect ratio of the two-component spinneret plate in the spinning assembly is 2.5, the upper layer filter screen of the double-layer circular filter screen in the spinning assembly has a mesh number of 200 meshes, and the lower layer filter screen has a mesh number of 50 meshes.

[0055] The side blowing cooling is at 25℃ and the humidity is 65%.

[0056] The gathering and oiling adopt oil wheel oiling, the oil agent used is a polyester fiber special oil agent, and the oiling amount is 0.8%.

[0057] The hot roller temperature of the hot roller drawing is 130℃, and the drawing ratio is 1.5.

[0058] The network interlacing adopts an air network nozzle to make each filament in the yarn entangled.

[0059] Example 2

[0060] A photochromic polyester fiber comprises a core layer and a skin layer, and the skin-to-core ratio is 20:80; the raw material of the core layer comprises 3% photochromic polyester masterbatch and the balance of low-melting-point polyester chips in terms of percentage by weight; and the raw material of the skin layer is conventional polyester chips.

[0061] The raw material of the photochromic polyester masterbatch comprises photochromic powder, titanate coupling agent, low-melting-point polyester powder, diatomite, and aluminum nitride; the weight ratio of the photochromic powder, the titanate coupling agent, and the low-melting-point polyester powder is 10:1:80; the addition amount of diatomite is 8% and the addition amount of aluminum nitride is 15% according to the mass of the low-melting-point polyester powder; and the titanate coupling agent is isopropyl titanate and tetrabutyl titanate with a mass ratio of 1:0.4.

[0062] The preparation method of the photochromic polyester masterbatch comprises the following steps:

[0063] (1) The low-melting-point polyester chips are crushed after being subjected to deep cooling treatment at -50℃ for 8min, are sieved, and low-melting-point polyester powder with an average particle size of 200 meshes is obtained.

[0064] (2) mixing photochromic powder, titanate coupling agent, low-melting polyester powder, diatomite and aluminum nitride according to the formula amount, stirring at 85℃, 300rpm for 30min to obtain a mixed powder;

[0065] (3) adding the mixed powder into a single screw extruder, setting the temperature partition as 185℃ for the first zone, 195℃ for the second zone, 195℃ for the third zone, 200℃ for the fourth zone, and 200℃ for the fifth zone, and preparing the photochromic polyester master batch by means of water cooling and pelletizing system with water temperature of 25±2℃.

[0066] The preparation method of the photochromic polyester fiber comprises the following steps:

[0067] The core layer raw material and the skin layer raw material are respectively fed into the screw extruder for melting, the core layer melt and the skin layer melt are metered by the metering pump and then enter the dual-component spinning assembly, the fiber bundle is formed after being sprayed out of the spinning assembly, and the fiber bundle is cooled by side blowing, oiled by bunching, stretched by hot roller, interlaced by network, and finally wound to form a photochromic polyester fiber;

[0068] The melting temperature of the core layer raw material is 195℃, the melting temperature of the skin layer raw material is 265℃, and the winding forming rate is 3500m / min.

[0069] The spinning assembly comprises a spinning assembly, the aspect ratio of the double-component spinneret plate in the spinning assembly is 2.5, and the upper layer filter screen of the double-layer circular filter screen in the spinning assembly has a mesh number of 200 meshes, and the lower layer filter screen has a mesh number of 50 meshes.

[0070] The side blowing cooling is at 20℃, and the humidity is 65%.

[0071] The oiling by bunching adopts oil wheel oiling, the oil agent used is a polyester fiber special oil agent, and the oiling amount is 0.6%.

[0072] The hot roller temperature of the hot roller stretching is 100℃, and the stretching ratio is 1.3.

[0073] The network interlacing adopts an air network nozzle to make each filament in the fiber bundle entangle and intertwine.

[0074] Example 3

[0075] A photochromic polyester fiber comprises a core layer and a skin layer, and the skin-to-core ratio is 20:80; the raw material of the core layer comprises 7% photochromic polyester master batch and the balance of low-melting polyester chips in terms of weight percentage; and the raw material of the skin layer is a conventional polyester chip.

[0076] The raw materials of the photochromic polyester masterbatch include photochromic powder, titanate coupling agent, low-melting-point polyester powder, diatomaceous earth and aluminum nitride; wherein the weight ratio of the photochromic powder, titanate coupling agent and low-melting-point polyester powder is 20:2:90; based on the mass of the low-melting-point polyester powder, the added amount of diatomaceous earth is 12% and the added amount of aluminum nitride is 20%; the titanate coupling agent is isopropyl titanate and tetrabutyl titanate in a mass ratio of 1:0.7;

[0077] The preparation method of the photochromic polyester masterbatch comprises the following steps:

[0078] (1) subjecting low-melting-point polyester chips to a cryogenic treatment at -120°C for 10 minutes, crushing the chips, and sieving the chips to obtain low-melting-point polyester powder having an average particle size of 200 meshes;

[0079] (2) mixing the photochromic powder, titanate coupling agent, low melting point polyester powder, diatomaceous earth and aluminum nitride according to the formula amount, and stirring at 90° C. and 400 rpm for 40 minutes to obtain a mixed powder;

[0080] (3) The mixed powder is added into a single-screw extruder, and the temperature zones are set as 185°C in zone 1, 195°C in zone 2, 195°C in zone 3, 200°C in zone 4, and 200°C in zone 5. The melt is subjected to a water-cooled pelletizing system at a water temperature of 25±2°C to obtain the photochromic polyester masterbatch.

[0081] The preparation method of the photochromic polyester fiber comprises the following steps:

[0082] The core layer raw material and the skin layer raw material are respectively fed into a screw extruder for melting. The core layer melt and the skin layer melt are metered by a metering pump and then enter a two-component spinning assembly. After being composited and ejected from the spinning assembly, a tow is formed. The tow is cooled by side blowing, bundled and oiled, drawn by a hot roller, interwoven, and finally wound to obtain a photochromic polyester fiber.

[0083] The melting temperature of the core layer material is 245°C, the melting temperature of the skin layer material is 295°C, and the winding forming rate is 5500m / min;

[0084] The spinning assembly includes a spinneret assembly, the aspect ratio of the two-component spinneret in the spinneret assembly is 2.5, the mesh number of the upper filter layer of the double-layer circular filter in the spinneret assembly is 200 mesh, and the mesh number of the lower filter layer is 50 mesh;

[0085] The side-blown air cooling is 30°C and the humidity is 70%;

[0086] The cluster is oiled by an oil tanker, and the oil used is a special oil for polyester fiber, and the oiling amount is 0.9%;

[0087] The hot roller temperature of the hot roller drafting is 140℃, and the drafting ratio is 1.7.

[0088] The network interweaving adopts air network nozzles to make each single fiber in the fiber bundle entangle.

[0089] Comparative Example 1

[0090] The difference between the preparation method of Example 1 is that the raw materials of the photochromic polyester master batch only include photochromic powder, titanate coupling agent, and low-melting-point polyester powder; wherein the weight ratio of the photochromic powder, the titanate coupling agent, and the low-melting-point polyester powder is 15:1.5:83.5. The remaining preparation steps and process parameters are the same as those of Example 1.

[0091] Comparative Example 2

[0092] The difference between the preparation method of Example 1 is that the raw materials of the photochromic polyester master batch only include photochromic powder, titanate coupling agent, low-melting-point polyester powder, and diatomite; wherein the weight ratio of the photochromic powder, the titanate coupling agent, and the low-melting-point polyester powder is 15:1.5:83.5; the addition amount of diatomite is 28% according to the mass of the low-melting-point polyester powder; and the remaining preparation steps and process parameters are the same as those of Example 1.

[0093] Comparative Example 3

[0094] The difference between the preparation method of Example 1 is that the raw materials of the photochromic polyester master batch only include photochromic powder, titanate coupling agent, low-melting-point polyester powder, and aluminum nitride; wherein the weight ratio of the photochromic powder, the titanate coupling agent, and the low-melting-point polyester powder is 15:1.5:83.5; the addition amount of aluminum nitride is 28% according to the mass of the low-melting-point polyester powder; and the remaining preparation steps and process parameters are the same as those of Example 1.

[0095] Comparative Example 4

[0096] The difference between the preparation method of Example 1 is that the raw materials of the photochromic polyester master batch include photochromic powder, titanate coupling agent, low-melting-point polyester powder, diatomite, and aluminum nitride; wherein the weight ratio of the photochromic powder, the titanate coupling agent, and the low-melting-point polyester powder is 15:1.5:83.5; the addition amount of diatomite is 18% and the addition amount of aluminum nitride is 10% according to the mass of the low-melting-point polyester powder; and the remaining preparation steps and process parameters are the same as those of Example 1.

[0097] Comparative Example 5

[0098] The difference between the preparation method of Example 1 is that the hot roller temperature of the hot roller drafting is 130℃, and the drafting ratio is 1.1; and the remaining preparation steps and process parameters are the same as those of Example 1.

[0099] Comparative Example 6

[0100] The difference between the preparation method of Example 1 is that the hot roller temperature of the hot roller drafting is 160℃, and the drafting ratio is 1.5; the rest of the preparation steps and process parameters are the same as those of Example 1.

[0101] Comparative Example 7

[0102] The difference between the preparation method of Example 1 is that the melting temperature of the core layer raw material and the skin layer raw material is 280℃; the rest of the preparation steps and process parameters are the same as those of Example 1.

[0103] Comparative Example 8

[0104] The difference between the preparation method of Example 1 is that the winding forming rate is 2500m / min; the rest of the preparation steps and process parameters are the same as those of Example 1.

[0105] Test Example 1

[0106] The photochromic polyester fibers prepared in Examples 1-3 and Comparative Examples 1-4 are respectively woven into 20x20cm samples, and the evaporation rate (g / h) of the samples is tested according to GB / T 21655.1-2008 "Evaluation of moisture absorption and drying speed of textiles", and the test results are shown in Table 1.

[0107] Table 1

[0108] Group Evaporation rate (g / h) Example 1 0.29 Example 2 0.25 Example 3 0.33 Comparative Example 1 0.06 Comparative Example 2 0.15 Comparative Example 3 0.09 Comparative Example 4 0.20

[0109] The test results show that when the photochromic polyester fiber prepared by the present application is woven into a sample, the sample has better air permeability.

[0110] According to the data of Example 1 and Comparative Examples 1-3, the evaporation rate of the finished products of Comparative Examples 1-3 is significantly lower than that of Example 1, which may be because diatomite itself has a porous structure and a large specific surface area, which can significantly increase the porosity of the fiber, and aluminum nitride itself has good thermal conductivity, so that by compounding diatomite and aluminum nitride in polyester fiber, the specific surface area of the fiber can be increased, providing more channels for gas, thereby improving the air permeability of the finished product. Compared with Example 1, adjusting the amount and ratio of diatomite and aluminum nitride in Comparative Example 4 leads to a decrease in the air permeability of the finished product. This may be because the amount and ratio of diatomite and aluminum nitride affect the performance of the two, thereby affecting the air permeability of the finished product.

[0111] Test Example 2

[0112] The breaking strength and breaking elongation of the photochromic polyester fiber prepared are detected according to GB / T 14344-2003 "Test method of tensile properties of synthetic fiber filaments", and the test results are shown in Table 2.

[0113] Table 2

[0114]

[0115]

[0116] The greater the breaking strength and breaking elongation, the better the flexibility, strength and other mechanical properties of the product.

[0117] As shown in the data in Table 1, the experimental results show that the photochromic polyester fiber prepared in Examples 1-3 has good mechanical properties and softness, and the mechanical property indexes meet the standard of polyester filaments.

[0118] As shown in the data in Examples 1 and Comparative Examples 1-3, the mechanical properties of the products of Comparative Examples 1-3 are obviously lower than those of Example 1, which may be because: diatomite has high hardness and rigidity, and can improve the rigidity and strength of polyester fiber when added to the polyester fiber; aluminum nitride is a kind of inorganic material with high hardness and high thermal conductivity, which can play a role of reinforcing phase in the polyester matrix, improve the tensile strength of the material by dispersing stress, and improve the breaking elongation by improving the compatibility and dispersibility of diatomite and aluminum nitride in the polyester matrix through the action of coupling agent; when diatomite and aluminum nitride are added to the polyester fiber at the same time, a certain synergistic effect may be produced, thereby improving the mechanical properties of the polyester fiber. Compared with Example 1, the amount ratio of diatomite and aluminum nitride is adjusted in Comparative Example 4, thereby leading to the decrease of the mechanical properties of the photochromic polyester fiber, which may be because the amount ratio of diatomite and aluminum nitride is also a key factor for determining the mechanical properties of the polyester fiber, and when diatomite and aluminum nitride with the amount ratio of the application are selected, the polyester fiber has good mechanical properties.

[0119] Compared with Example 1, changing the draw ratio and the hot roller temperature in Comparative Example 5-6 respectively results in the mechanical properties of the photochromic polyester fiber prepared to be reduced, which can be attributed to the fact that: selecting a proper draw ratio for the hot roller drawing can make the polyester molecular chain highly oriented along the fiber axis, so that the crystalline region becomes regular, and the fiber breaking strength is significantly improved, while avoiding the polyester molecular chain from being stretched too much to be rigid, and the chain segment slipping when the fiber is stressed, which can absorb energy and thus maintain the breaking elongation at a high level; selecting a proper temperature for the hot roller drawing can make the polyester molecular chain be activated by heat when the fiber is stretched, and more easily oriented along the stretching direction to form a microcrystalline structure, so as to enhance the fiber breaking strength by increasing the crystallinity, and a proper hot roller temperature can also reduce the disordered accumulation of the polyester molecular chain when it relaxes, and the generation of microcracks due to local stress concentration in the amorphous region, thus the breaking elongation can be maintained at a high level.

[0120] Compared with Example 1, using the same temperature for spinning the core layer raw material and the skin layer raw material in Comparative Example 7 results in the mechanical properties of the finished product to be reduced. This can be attributed to the fact that using the same temperature for spinning can cause the surface of the fiber to partially melt or unevenly cool, forming more microcracks, microconvexities or irregular surface structures, which are more prone to stress concentration when subjected to external force interference, thus leading to the mechanical properties of the finished product to be reduced.

[0121] Compared with Example 1, adjusting the winding forming rate in Comparative Example 8 results in the mechanical properties of the finished product to be reduced. This can be attributed to the fact that a too low spinning rate limits the movement of the polyester molecular chain in the raw material, making the flexibility poor, thus significantly reducing the breaking elongation of the photochromic polyester fiber prepared and the mechanical properties of the finished product.

[0122] Test Example 3

[0123] The dynamic and static friction coefficients of the photochromic polyester fiber and the photochromic polyester fiber (F / F) were tested by using a Y151 fiber friction coefficient tester under the conditions of a rotation speed of 50 r / min and selecting a 100 mg tension clamp.

[0124] The friction coefficient test results of the photochromic polyester fiber prepared in Examples 1-3 and Comparative Examples 5-8 are shown in Table 3.

[0125] Table 3

[0126] Group (F / F) static friction coefficient μs (F / F) dynamic friction coefficient μd Example 1 0.104 0.121 Example 2 0.109 0.122 Example 3 0.118 0.131 Comparative Example 5 0.161 0.238 Comparative Example 6 0.183 0.257 Comparative Example 7 0.241 0.289 Comparative Example 8 0.263 0.315

[0127] The greater the static and dynamic friction coefficients, the rougher the product, and the more prone to fiber fluffing and floating during use.

[0128] From the data of Table 1, it can be seen that the photochromic polyester fibers prepared in Examples 1-3 have smaller static and dynamic friction coefficients, and less fiber fuzzing and floating during use.

[0129] Compared with Example 1, the preparation process parameters (such as draft ratio, hot roller temperature, melt temperature, and winding forming rate) of the photochromic polyester fibers in Comparative Examples 5-8 are changed respectively, resulting in the increase of the friction coefficient of the finished product, which may be because the change of the process parameters affects the arrangement and crystallization of the molecular chains in the photochromic polyester fibers, and this structural change affects the interaction force between the polyester molecular chains, at the same time, cracks and micro-convexities are formed on the surface of the fibers, thereby causing greater friction resistance when the photochromic polyester fibers move, and further leading to the increase of the static and dynamic friction coefficients. Therefore, the process parameters for preparing the photochromic polyester fibers in the present application are also important parameters affecting the roughness of the product. The polyester fibers prepared by the process parameters in the present application have good static and dynamic friction coefficients, and less fiber fuzzing and floating during use.

[0130] Test Example 4

[0131] The photochromic polyester fibers prepared in Example 1 were irradiated under a 4W ultraviolet lamp for 180 seconds, and the color development of the fibers was observed (see Figure 1 ), as well as the color change of the fibers after leaving the ultraviolet light source for 180 seconds (see Figure 2 ).

[0132] As can be seen from Figures 1-2 , the photochromic polyester fibers prepared in Example 1 basically recover the original color after leaving the light source for 180 seconds, which shows that the fading performance of the photochromic polyester fibers is good and there is no chemical change and other losses during the change, which is a reversible physical behavior.

[0133] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application and not to limit the protection scope of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A photochromic polyester fiber, characterized in that: The photochromic polyester fiber comprises a core layer and a skin layer, and the skin-to-core ratio is 20-80:80-20; Calculated by weight percentage, the raw materials of the core layer include 1%-10% of photochromic polyester masterbatch and the balance of low-melting-point polyester chips; The raw materials of the photochromic polyester masterbatch include photochromic powder, titanate coupling agent, low-melting-point polyester powder, diatomaceous earth and aluminum nitride; wherein the weight ratio of the photochromic powder, titanate coupling agent and low-melting-point polyester powder is 10-20:1-2:80-90; based on the mass of the low-melting-point polyester powder, the amount of diatomaceous earth added is 8%-12%, and the amount of aluminum nitride added is 15%-20%; The raw material of the skin layer is conventional polyester chips.

2. The photochromic polyester fiber according to claim 1, wherein The preparation method of the photochromic polyester masterbatch comprises the following steps: (1) subjecting low-melting-point polyester chips to cryogenic treatment and then crushing them to obtain the low-melting-point polyester powder; (2) mixing the photochromic powder, titanate coupling agent, low melting point polyester powder, diatomaceous earth and aluminum nitride according to the formula amount to obtain a mixed powder; (3) The mixed powder is extruded into pellets by a single-screw extruder to obtain the photochromic polyester masterbatch.

3. The photochromic polyester fiber according to claim 2, wherein In step (1), the temperature of the cryogenic treatment is -120 to -50°C and the time is 8 to 12 minutes; in step (2), the temperature of the mixing is 85 to 95°C, the rotation speed is 300 to 500 rpm, and the time is 30 to 60 minutes.

4. The photochromic polyester fiber according to claim 2, wherein In step (1), the melting point of the low-melting polyester chips is 180-220° C., and the average particle size of the crushed low-melting polyester powder is 100-300 meshes; in step (2), the average particle size of the photochromic powder is 400-600 nm.

5. The photochromic polyester fiber according to claim 1, wherein The photochromic powder is one or more of a spiro compound, a diarylethene, and azobenzene; the spiro compound is a spiropyran and / or spirooxazine containing a phenyl group and an ester group as substituents; and the titanate coupling agent is isopropyl titanate and / or tetrabutyl titanate.

6. The photochromic polyester fiber according to claim 5, wherein The titanate coupling agent is isopropyl titanate and tetrabutyl titanate in a mass ratio of 1:0.4-0.

7.

7. The method for preparing the photochromic polyester fiber according to claim 1, wherein: The method comprises the following steps: feeding the core layer raw material and the skin layer raw material into a screw extruder for melting respectively; the core layer melt and the skin layer melt are metered by a metering pump and then enter a two-component spinning assembly; the filament bundle is formed after being compositely ejected from the spinning assembly; the filament bundle is cooled by side blowing, bundled and oiled, drawn by a hot roller, interwoven with a network, and finally wound to obtain the photochromic polyester fiber.

8. The method for preparing the photochromic polyester fiber according to claim 7, wherein: The melting temperature of the core layer raw material is 195-245°C, the melting temperature of the skin layer raw material is 265-295°C, and the winding forming rate is 3500-5500 m / min; the temperature of the side-blown air cooling is 20-30°C, and the humidity is 65%-70%; the spinning assembly includes a spinneret assembly, the aspect ratio of the spinneret in the spinneret assembly is 2.5, the upper filter mesh of the double-layer circular filter in the spinneret assembly is 200 mesh, and the lower filter mesh is 50 mesh; the temperature of the hot roller drawing is 100-140°C, and the drawing ratio is 1.3-1.7.

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