Polyvinyl alcohol photo-thermal fiber prepared by melt spinning and preparation method and application thereof

Abstract

The application discloses a kind of polyvinyl alcohol photo-thermal fiber prepared by melt spinning and its preparation method and application, which comprises the following steps: dopamine hydrochloride is stirred and dissolved in water to obtain dopamine hydrochloride aqueous solution, dopamine hydrochloride aqueous solution is mixed with polyvinyl alcohol and ethylene urea, and polydopamine / polyvinyl alcohol is generated by static swelling and plasticizing, melt spinning is carried out to prepare polyvinyl alcohol composite photo-thermal fiber.The application is a kind of polyvinyl alcohol photo-thermal fiber prepared by melt spinning, which is simple in process, does not need coagulation bath, has small pollution, low cost, and the prepared product has excellent photo-thermal performance, and the photo-thermal effect can be adjusted according to needs.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of functional fibers, and relates to a kind of polyvinyl alcohol light and heat fiber prepared by melt spinning and a preparation method and application thereof. BACKGROUND

[0002] Polyvinyl alcohol fiber is a synthetic fiber prepared from polyvinyl alcohol (PVA) as raw material by spinning, which has excellent mechanical properties, corrosion resistance, hydrophilic properties, and is known as "synthetic cotton". It has once replaced cotton and been widely used in the field of textile and clothing. In recent years, various PVA fibers with special functions have been developed, such as water-soluble, flame-retardant, high-strength and high-modulus, etc., which have good development prospects. PVA fibers are mainly prepared by wet spinning or dry-wet spinning, but both methods have certain defects, such as complex process, need for coagulation bath and large amount of water, serious pollution, long cycle, high energy consumption, which limits the practical application of PVA. The melt spinning process is simple, efficient, does not need coagulation bath, has small pollution and low cost, which is an important research direction at present. However, PVA is a polyhydroxy polymer, and its melting point and decomposition temperature are very close, which makes it difficult to be melt-spun.

[0003] In recent years, the industrialization of fibers has developed rapidly with the increasing international competition, and ordinary fibers have been unable to meet people's expectations and pursuit of higher quality of life. People's attention to fibers has gradually shifted from ordinary fibers to new fibers with comfort function, high added value and intelligence. Various types of new functional fibers, such as antibacterial and health care fibers, moisture-wicking fibers, heating fibers, play an important role in improving people's life and promoting production progress. In recent years, health care clothes, quick-drying clothes, thermal clothes and other products made of various new functional fibers not only are favored by consumers, but also promote the development of the fiber industry. Intelligent temperature control textiles have developed rapidly in the 1990s, which not only meet people's requirements for temperature control clothing, but also improve the comfort of clothing and have high added value, becoming a high-tech product that can achieve high efficiency. With the continuous introduction of high-tech into this field, new functional fibers have a greater and greater impact on people's lives, and people's requirements for functional finishing textiles are also higher and higher. In order to meet people's needs, various new functional textiles will inevitably have good development prospects and broad application prospects.

[0004] Photo-thermal conversion fiber is a kind of functional fiber that can absorb certain light, especially near-infrared light, and generate heat through plasmonic resonance or energy transition band to achieve local heating. It is favored because it can convert near-infrared light into heat energy, and has broad application prospects in biological applications and clothing fields. It is a current research hotspot to develop high-performance photo-thermal conversion fiber film materials. However, most photo-thermal fibers are prepared by dry-wet spinning or electrospinning method, which is complicated, involves high-voltage electricity, has low safety factor and small production.

[0005] Polydopamine (PDA) is a kind of mussel biomimetic material, which has excellent adhesion, hydrophilicity and biocompatibility, and is widely used in many fields, including biological imaging and material surface functionalization carrier, etc. It has attracted widespread attention. Polydopamine has high light absorption characteristics in the near-infrared spectrum, similar to the polymerization mechanism of natural melanin. Polydopamine has gradually become a hot material in photo-thermal conversion research due to its unique photo-thermal performance. At present, there are many studies on the application of PDA in coating, including its application in the field of polymer composites, such as filling some inorganic nano-material enhancers coated with PDA into polymers, which endows the polymers with photo-thermal performance, free radical scavenging and other functions. However, few people study PDA particles as enhancers filled into polymers.

[0006] Patent CN1786302A proposes a method for preparing high-performance polyvinyl alcohol fibers by adding small molecule modifiers to polyvinyl alcohol to form intermolecular compliance for melt spinning. However, there are many types of small molecule additives, complex extraction and high cost, and it does not have photo-thermal performance.

[0007] Therefore, it is particularly important to find a preparation method of polyvinyl alcohol photo-thermal fiber which is simple, has few types of raw materials, has photo-thermal performance and the photo-thermal effect can be adjusted as needed. SUMMARY

[0008] In view of the problems existing in the prior art, the present application provides a method for preparing polyvinyl alcohol photo-thermal fiber by melt spinning, and its preparation method and application. The preparation method of the present application is simple, convenient to operate, has few types of raw materials, and the polyvinyl alcohol photo-thermal fiber has photo-thermal performance and the photo-thermal effect can be adjusted as needed.

[0009] In order to achieve the above purpose, the technical scheme of the present application is as follows:

[0010] A method for preparing polyvinyl alcohol photo-thermal fiber by melt spinning, comprising the following steps:

[0011] (1) Dopamine hydrochloride is stirred and dissolved in water to obtain a dopamine hydrochloride aqueous solution;

[0012] (2) The dopamine hydrochloride aqueous solution obtained in step (1) is mixed with polyvinyl alcohol and ethylene urea, and is left to swell and plasticize to generate a polydopamine / polyvinyl alcohol solution;

[0013] (3) The polydopamine / polyvinyl alcohol solution obtained in step (2) is melt spun to prepare a polyvinyl alcohol composite photothermal fiber.

[0014] The mass concentration of the dopamine hydrochloride aqueous solution in step (1) is 0.5%-4%.

[0015] The mass ratio of the dopamine hydrochloride aqueous solution, polyvinyl alcohol and ethylene urea in step (2) is 2-4:13-17:1-3.

[0016] The polyvinyl alcohol used in step (2) is PVA1799 type or PVA2499 type.

[0017] The standing condition in step (2) is a temperature of 50-80℃ and a time of 3-6 hours.

[0018] The temperature for melt spinning in step (3) is 180-200℃, the spinning speed is 200-800 m / min, and the draw ratio is 1.5-5 times.

[0019] The polyvinyl alcohol fiber has a photothermal effect which can be adjusted as needed, and can be heated to 56-91℃ within 20 seconds under the irradiation of 1 sun.

[0020] The tensile strength of the polyvinyl alcohol photothermal fiber is 3.03-4.15 cN / dtex. The polyvinyl alcohol photothermal fiber can be applied in the fields of biological application and clothing.

[0021] The present application has the following advantages:

[0022] 1. The present application provides a method for preparing a polyvinyl alcohol fiber with photothermal function by in-situ polymerization modification of polydopamine. In the process of polyvinyl alcohol plasticization, basic ethylene urea and dopamine hydrochloride are added. The basic environment provided by ethylene urea is used for in-situ polymerization of dopamine hydrochloride into polydopamine in the process of polyvinyl alcohol plasticization. Then the plasticized polyvinyl alcohol is melt spun to prepare a polyvinyl alcohol fiber with photothermal function, realizing one-step preparation of a polydopamine-containing polyvinyl alcohol functional fiber, which is simple in process and easy to operate.

[0023] 2、Polydopamine contains a large number of hydroxyl, imino and other groups, which can form hydrogen bonds with the carbonyl groups in polyvinyl alcohol, effectively improving the mechanical properties of the composite material, so that the polyvinyl alcohol fiber prepared by the method of the present application has good light and heat performance and excellent mechanical properties. The tensile strength of the polyvinyl alcohol light and heat fiber is 3.03-4.15 cN / dtex, and the temperature can be raised by 56-91℃ within 20 seconds under the irradiation of 1 sunlight.

[0024] 3、In the present application, ethylene urea is used as a plasticizer, and water and ethylene urea are used as a composite plasticizer to plasticize and modify polyvinyl alcohol, and then a melt spinning process is used to prepare polyvinyl alcohol composite fiber with light and heat function, which eliminates some processes in the solution spinning process, such as polymer dissolution, spinning solution filtration and solvent recovery; at the same time, since there is no solvent involved in the spinning process, the harm to the environment is reduced. The production process of the method is simple, has little environmental pollution and low production cost. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the following embodiment or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0026] Figure 1 The pictures of plasticized polyvinyl alcohol of Example 1 and Comparative Example 1, wherein a is the picture of plasticized polyvinyl alcohol of Comparative Example 1, and b is the picture of plasticized polyvinyl alcohol of Example 1.

[0027] Figure 2 The infrared spectra of the samples of Example 1 and Comparative Example 1, wherein a is the infrared spectrum of the sample of Comparative Example 1, and b is the infrared spectrum of the sample of Example 1.

[0028] Figure 3 The scanning electron microscope image of the cross section of the polyvinyl alcohol light and heat fiber of Example 1.

[0029] Figure 4 The temperature rising curves of the fibers obtained in Example 1-5 and Comparative Example 1 under simulated sunlight. Wherein a is the temperature rising curve of the fiber obtained in Comparative Example 1 under simulated sunlight, b is the temperature rising curve of the fiber obtained in Example 1 under simulated sunlight, c is the temperature rising curve of the fiber obtained in Example 2 under simulated sunlight, d is the temperature rising curve of the fiber obtained in Example 3 under simulated sunlight, e is the temperature rising curve of the fiber obtained in Example 4 under simulated sunlight, and f is the temperature rising curve of the fiber obtained in Example 5 under simulated sunlight. DETAILED DESCRIPTION

[0030] The technical solutions of the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative effort fall within the scope of the present application.

[0031] Embodiment 1

[0032] The method for preparing polyvinyl alcohol photo-thermal fiber by melt spinning in this embodiment is as follows:

[0033] 4 grams of dopamine hydrochloride was added to 100 grams of deionized water, and stirred to dissolve the dopamine hydrochloride to obtain a dopamine hydrochloride aqueous solution;

[0034] 20 grams of the dopamine hydrochloride aqueous solution, 65 grams of polyvinyl alcohol (1799) and 10 grams of ethylene urea were put into a high-speed mixer and mixed uniformly; and the mixture was left to stand at 80℃ for 3 hours for full swelling and plasticization; in this process, due to the alkaline environment provided by the ethylene urea, the dopamine hydrochloride polymerized in situ to form polydopamine in the plasticized polyvinyl alcohol;

[0035] The plasticized polydopamine / polyvinyl alcohol was spun according to the melt spinning method, the spinning temperature was 180℃, the spinning speed was 800 m / min, and the draw ratio was 5 times, to obtain the polyvinyl alcohol composite photo-thermal fiber.

[0036] Comparative Example 1

[0037] The method for preparing polyvinyl alcohol photo-thermal fiber by melt spinning in this embodiment is as follows:

[0038] 20 grams of deionized water, 65 grams of polyvinyl alcohol (1799) and 10 grams of ethylene urea were put into a high-speed mixer and mixed uniformly; and the mixture was left to stand at 80℃ for 3 hours for full swelling and plasticization;

[0039] The plasticized polydopamine / polyvinyl alcohol was spun according to the melt spinning method, the spinning temperature was 180℃, the spinning speed was 800 m / min, and the draw ratio was 5 times, to obtain the polyvinyl alcohol composite photo-thermal fiber.

[0040] The plasticized polyvinyl alcohol is as follows: Figure 1 It can be seen from the figure that Comparative Example 1 is white, and Example 1 is black, and polydopamine is formed in the plasticized polyvinyl alcohol of Example 1.

[0041] Figure 2 is the infrared spectrum of the samples obtained in Example 1 and Comparative Example 1, wherein curve a is Comparative Example 1, and curve b is Example 1. Comparative Example 1 has a peak at 3425 cm -1There is a strong O-H absorption peak. When PDA is added, the O-H stretching vibration peak gradually moves to low wave number, and the O-H absorption peak in Example 1 moves to 3412 cm -1 , which indicates that hydrogen bonds are generated between polydopamine and polyvinyl alcohol.

[0042] Figure 3 The scanning electron microscope pictures of the cross section of the polyvinyl alcohol photo-thermal fiber obtained in Example 1 are shown in (a) with a magnification of 1000 times and (b) with a magnification of 10000 times. It can be seen from the pictures that PDA is well dispersed in PVA without agglomeration, which indicates that the interaction between PDA nanoparticles and the matrix PVA is good and the compatibility is good.

[0043] It is tested that the surface temperature of the sample after irradiation in Example 1 is 91℃, and the tensile strength is 4.66 cN / dtex. The surface temperature of the sample after irradiation in Comparative Example 1 is 37℃, and the tensile strength is 2.53 cN / dtex. By adding only dopamine hydrochloride, the tensile strength of the sample is obviously improved.

[0044] Example 2

[0045] The method for preparing a polyvinyl alcohol photo-thermal fiber by melt spinning in this example has the following steps:

[0046] 3 grams of dopamine hydrochloride were added to 100 parts of deionized water, and the dopamine hydrochloride was stirred to dissolve, to obtain a dopamine hydrochloride aqueous solution.

[0047] 10 grams of the dopamine hydrochloride aqueous solution, 75 grams of polyvinyl alcohol (2499), and 15 grams of ethylene urea were put into a high-speed mixer and mixed uniformly; and the mixture was left to stand at 50℃ for 6 hours for swelling and plasticization. During this process, dopamine hydrochloride was polymerized in situ to form polydopamine due to the alkaline environment provided by ethylene urea.

[0048] The plasticized polydopamine / polyvinyl alcohol was spun according to the melt spinning method, the spinning temperature was 200℃, the spinning speed was 200 m / min, and the draw ratio was 1.5 times, to obtain the polyvinyl alcohol composite photo-thermal fiber.

[0049] It is tested that the surface temperature of the sample after irradiation in Example 1 is 91℃, and the tensile strength is 4.66 cN / dtex. The surface temperature of the sample after irradiation in Comparative Example 1 is 37℃, and the tensile strength is 2.53 cN / dtex. By adding only dopamine hydrochloride, the tensile strength of the sample is obviously improved.

[0050] Example 3

[0051] The method for preparing a polyvinyl alcohol photo-thermal fiber by melt spinning in this example has the following steps:

[0052] 1 gram of dopamine hydrochloride was added to 100 parts of deionized water, and the dopamine hydrochloride was stirred to dissolve, to obtain a dopamine hydrochloride aqueous solution.

[0053] 10 grams of dopamine hydrochloride aqueous solution, 85 grams of polyvinyl alcohol (1799), 5 grams of ethylene urea are put into a high-speed mixer and mixed uniformly; swell and plasticize at 70°C for 5 hours; during this process, dopamine hydrochloride is polymerized in situ to form polydopamine due to the basic environment provided by ethylene urea.

[0054] The plasticized polydopamine / polyvinyl alcohol is spun according to the melt spinning method, the spinning temperature is 195°C, the spinning speed is 500 m / min, and the draw ratio is 3 times, so as to obtain polyvinyl alcohol composite photo-thermal fiber.

[0055] After testing, the surface temperature of the sample in Example 3 after irradiation is 60°C, and the tensile strength is 3.23 cN / dtex.

[0056] Example 4

[0057] The method for preparing polyvinyl alcohol photo-thermal fiber by melt spinning in this example is as follows:

[0058] 3.5 grams of dopamine hydrochloride is added to 100 parts of deionized water, and stirred to dissolve the dopamine hydrochloride, to obtain dopamine hydrochloride aqueous solution.

[0059] 18 grams of dopamine hydrochloride aqueous solution, 80 grams of polyvinyl alcohol (1799), and 5 grams of ethylene urea are put into a high-speed mixer and mixed uniformly; swell and plasticize at 55°C for 5 hours; during this process, dopamine hydrochloride is polymerized in situ to form polydopamine due to the basic environment provided by ethylene urea.

[0060] The plasticized polydopamine / polyvinyl alcohol is spun according to the melt spinning method, the spinning temperature is 185°C, the spinning speed is 400 m / min, and the draw ratio is 3.5 times, so as to obtain polyvinyl alcohol composite photo-thermal fiber.

[0061] After testing, the surface temperature of the sample in Example 4 after irradiation is 81°C, and the tensile strength is 4.15 cN / dtex.

[0062] Example 5

[0063] The method for preparing polyvinyl alcohol photo-thermal fiber by melt spinning in this example is as follows:

[0064] 0.5 grams of dopamine hydrochloride is added to 100 parts of deionized water, and stirred to dissolve the dopamine hydrochloride, to obtain dopamine hydrochloride aqueous solution.

[0065] 11 grams of dopamine hydrochloride aqueous solution, 70 grams of polyvinyl alcohol (1799), and 15 grams of ethylene urea are put into a high-speed mixer and mixed uniformly; swell and plasticize at 65°C for 4.5 hours; during this process, dopamine hydrochloride is polymerized in situ to form polydopamine due to the basic environment provided by ethylene urea.

[0066] The plasticized polydopamine / polyvinyl alcohol is spun according to a melt spinning method, the spinning temperature is 188°C, the spinning speed is 700 m / min, and the draw ratio is 2 times, so that the polyvinyl alcohol composite photothermal fiber is prepared.

[0067] After testing, the surface temperature of the sample after irradiation in Example 5 is 56°C, and the tensile strength is 3.03 cN / dtex.

[0068] Example 6

[0069] The method for preparing the polyvinyl alcohol photothermal fiber by melt spinning in this example has the following steps:

[0070] One gram of dopamine hydrochloride is added to 100 parts of deionized water, and the dopamine hydrochloride is stirred to dissolve, to obtain a dopamine hydrochloride aqueous solution.

[0071] Fifteen grams of the dopamine hydrochloride aqueous solution, 67 grams of polyvinyl alcohol (1799), and 15 grams of ethylene urea are put into a high-speed mixer and mixed uniformly; and the mixture is left to stand at 65°C for 4 hours for full swelling and plasticization; in this process, the dopamine hydrochloride is polymerized in situ into polydopamine due to the basic environment provided by the ethylene urea.

[0072] The plasticized polydopamine / polyvinyl alcohol is spun according to a melt spinning method, the spinning temperature is 188°C, the spinning speed is 700 m / min, and the draw ratio is 2 times, so that the polyvinyl alcohol composite photothermal fiber is prepared.

[0073] After testing, the surface temperature of the sample after irradiation in Example 5 is 56°C, and the tensile strength is 3.03 cN / dtex.

[0074] Example 7

[0075] The method for preparing the polyvinyl alcohol photothermal fiber by melt spinning in this example has the following steps:

[0076] Three grams of dopamine hydrochloride is added to 100 parts of deionized water, and the dopamine hydrochloride is stirred to dissolve, to obtain a dopamine hydrochloride aqueous solution.

[0077] Fifteen grams of the dopamine hydrochloride aqueous solution, 67 grams of polyvinyl alcohol (1799), and 15 grams of ethylene urea are put into a high-speed mixer and mixed uniformly; and the mixture is left to stand at 65°C for 4 hours for full swelling and plasticization; in this process, the dopamine hydrochloride is polymerized in situ into polydopamine due to the basic environment provided by the ethylene urea.

[0078] The plasticized polydopamine / polyvinyl alcohol is spun according to a melt spinning method, the spinning temperature is 188°C, the spinning speed is 700 m / min, and the draw ratio is 2 times, so that the polyvinyl alcohol composite photothermal fiber is prepared.

[0079] The surface temperature of the sample after irradiation in Example 5 was 66℃, and the tensile strength was 3.72 cN / dtex.

[0080] Example 8

[0081] The method for preparing the polyvinyl alcohol photo-thermal fiber in this embodiment by melt spinning is as follows:

[0082] Dopamine hydrochloride was added to 100 parts of deionized water, and stirred to dissolve the dopamine hydrochloride to obtain a dopamine hydrochloride aqueous solution.

[0083] The dopamine hydrochloride aqueous solution, 68 grams of polyvinyl alcohol (1799), and 15 grams of ethylene urea were mixed in a high-speed mixer, and then left to stand at 72℃ for 5 hours to swell and plasticize fully. During this process, the dopamine hydrochloride was polymerized in situ to form polydopamine due to the basic environment provided by the ethylene urea.

[0084] The plasticized polydopamine / polyvinyl alcohol was spun by the melt spinning method, the spinning temperature was 192℃, the spinning speed was 700 m / min, and the draw ratio was 2 times, thereby obtaining the polyvinyl alcohol composite photo-thermal fiber.

[0085] The surface temperature of the sample after irradiation in Example 5 was 63℃, and the tensile strength was 3.14 cN / dtex.

[0086] Example 9

[0087] The method for preparing the polyvinyl alcohol photo-thermal fiber in this embodiment by melt spinning is as follows:

[0088] Dopamine hydrochloride was added to 100 parts of deionized water, and stirred to dissolve the dopamine hydrochloride to obtain a dopamine hydrochloride aqueous solution.

[0089] The dopamine hydrochloride aqueous solution, 68 grams of polyvinyl alcohol (1799), and 15 grams of ethylene urea were mixed in a high-speed mixer, and then left to stand at 72℃ for 5 hours to swell and plasticize fully. During this process, the dopamine hydrochloride was polymerized in situ to form polydopamine due to the basic environment provided by the ethylene urea.

[0090] The plasticized polydopamine / polyvinyl alcohol was spun by the melt spinning method, the spinning temperature was 192℃, the spinning speed was 700 m / min, and the draw ratio was 2 times, thereby obtaining the polyvinyl alcohol composite photo-thermal fiber.

[0091] The surface temperature of the sample after irradiation in Example 5 was 63℃, and the tensile strength was 3.14 cN / dtex.

[0092] Example 10

[0093] The method for preparing the polyvinyl alcohol photo-thermal fiber by melt spinning in the embodiment is as follows:

[0094] 0.5 g of dopamine hydrochloride was added to 100 parts of deionized water, and stirred to dissolve the dopamine hydrochloride, to obtain a dopamine hydrochloride aqueous solution.

[0095] 11 g of the dopamine hydrochloride aqueous solution, 70 g of polyvinyl alcohol (1799), and 15 g of ethylene urea were put into a high-speed mixer and mixed uniformly; and then, the mixture was left to stand at 65℃ for 5 hours to swell and plasticize fully; and in this process, the dopamine hydrochloride was polymerized in situ to form polydopamine due to the alkaline environment provided by the ethylene urea.

[0096] The plasticized polydopamine / polyvinyl alcohol was spun by the melt spinning method, the spinning temperature was 188℃, the spinning speed was 700 m / min, and the draw ratio was 2 times, to obtain the polyvinyl alcohol composite photo-thermal fiber.

[0097] It was tested that the surface temperature of the sample after irradiation in Example 5 was 83℃, and the tensile strength was 4.01 cN / dtex.

[0098] Effect analysis of the embodiment

[0099] The fiber mechanical properties were tested according to the test method for tensile properties of chemical fiber filaments (GB / T 14344-2008); the photo-thermal properties were tested by using simulated sunlight (intensity of 1 sun) to irradiate the fiber, and the fiber temperature rising curve was recorded by means of an infrared thermal imager.

[0100] The fibers obtained in Examples 1-5 and Comparative Example 1 were subjected to the temperature rising curve under simulated sunlight, as shown in Figure 4 It can be seen from Figure 4 that the temperature of Comparative Example 1 only rose to about 37℃ within 20 seconds under the irradiation of 1 sun, while the temperatures of Examples 1, 2, 3, 4, and 5 rose to 91℃, 72℃, 60℃, 81℃, and 56℃, respectively, within 20 seconds, which indicates that the polyvinyl alcohol fiber prepared by the melt spinning method of the patent has good photo-thermal effect, and the photo-thermal effect can be adjusted as needed.

[0101] The above only describes the preferred embodiments of the present application, and is not intended to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing polyvinyl alcohol photothermal fibers by melt spinning, comprising the following steps: (1) Dissolve dopamine hydrochloride in water by stirring to obtain an aqueous solution of dopamine hydrochloride; (2) The hydrochloric acid dopamine aqueous solution obtained in step (1) is mixed with polyvinyl alcohol and vinyl urea, and allowed to stand to swell and plasticize to generate a polydopamine / polyvinyl alcohol solution; (3) The polydopamine / polyvinyl alcohol solution obtained in step (2) is melt-spun to obtain polyvinyl alcohol photothermal fiber.

2. The method for preparing polyvinyl alcohol photothermal fibers by melt spinning according to claim 1, characterized in that: In step (1), the mass concentration of the dopamine hydrochloride aqueous solution is 0.5%-4%.

3. The method for preparing polyvinyl alcohol photothermal fibers by melt spinning according to claim 2, characterized in that: In step (2), the mass ratio of dopamine hydrochloride aqueous solution, polyvinyl alcohol, and ethylene urea is 2-4:13-17:1-3.

4. The method for preparing polyvinyl alcohol photothermal fibers by melt spinning according to claim 3, characterized in that: In step (2), the polyvinyl alcohol used is either PVA1799 or PVA2499.

5. The method for preparing polyvinyl alcohol photothermal fibers by melt spinning according to claim 4, characterized in that: The settling conditions in step (2) are a temperature of 50-80℃ and a time of 3-6 hours.

6. The method for preparing polyvinyl alcohol photothermal fibers by melt spinning according to claim 5, characterized in that: In step (3), the temperature of melt spinning is 180-200℃, the spinning speed is 200-800m / min, and the draw ratio is 1.5-5 times.

7. The polyvinyl alcohol photothermal fiber prepared according to any one of claims 1-6, characterized in that: The polyvinyl alcohol photothermal fiber has a photothermal effect, and the photothermal effect can be adjusted as needed.

8. The polyvinyl alcohol photothermal fiber according to claim 7, characterized in that: The polyvinyl alcohol photothermal fiber can reach a temperature of 56-91°C within 20 seconds under sunlight.

9. The polyvinyl alcohol photothermal fiber according to claim 8, characterized in that: The tensile strength of the polyvinyl alcohol photothermal fiber is 3.03-4.15 cN / dtex.

10. The application of the polyvinyl alcohol photothermal fiber according to claim 9 in the fields of biological applications and clothing.

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