Preparation method of a phase change energy storage fiber and its fabric

Abstract

The present invention relates to the field of fiber technology, and discloses a preparation method of phase change energy storage fibers and their fabrics. In the present invention, ultraviolet irradiation grafting modification is carried out on polyethylene terephthalate (PET) using graft monomers, and then electrospinning is carried out with a eutectic fatty acid phase change material composed of capric acid, lauric acid, etc. The obtained phase change energy storage fibers exhibit different melting temperatures and melting enthalpy values, and have good phase change heat storage performance and flame retardant performance. It improves the interfacial bonding force between the eutectic phase change material and the PET fiber, reduces the adverse impact of the eutectic phase change material on the mechanical properties of the PET fiber, and enables the PET fiber felt to maintain high tensile strength, elongation at break and mechanical properties.

Description

Technical Field

[0001] The present invention relates to the technical field of fibers, and specifically to a preparation method of phase change energy storage fibers and their fabrics. Background Art

[0002] Phase change materials can absorb and release a large amount of heat during the phase transition process, thereby effectively storing thermal energy and regulating temperature. They are a clean and renewable latent heat storage material and have extensive applications in fields such as fiber clothing, construction, battery heat dissipation systems, aerospace, etc. Common phase change materials mainly include paraffin, polyethylene glycol, fatty acids such as stearic acid, and their eutectics.

[0003] Polyester fibers made of polyethylene terephthalate have good properties such as breaking strength, elastic modulus, heat resistance, and corrosion resistance, and are widely used in fiber clothing, textiles, etc. Developing new phase change energy storage polyester fiber fabrics is a research hotspot. Usually, adding phase change materials such as fatty acids will affect the mechanical properties such as the tensile strength of the fibers. Chinese Patent with the application number 200610037169.X discloses a preparation method of phase change energy storage ultrafine composite polyester fibers. Using stearic acid and its ester derivatives as phase change materials, coated inside the polyester matrix, the obtained polyester fibers have properties such as a large specific surface area, high porosity, and temperature regulation. However, the polyester fibers of this patent do not show good mechanical strength and flame retardant properties. Summary of the Invention

[0004] (1) Technical problems to be solved: Aiming at the deficiencies of the prior art, the problems of poor mechanical properties and flame retardancy of PET phase change fibers are solved.

[0005] (2) Technical solutions: A preparation method of phase change energy storage fibers: Step A: Add an acetone solution of benzophenone with a mass concentration of 0.3 - 1 g / L to a reaction vessel, stir and then add a polyethylene terephthalate film. Take out the film, dry to remove acetone, and then add the film to an ethanol solution of a graft monomer with a mass concentration of 30 - 150 g / L. Under a nitrogen atmosphere, irradiate with ultraviolet light and carry out a graft reaction for 30 - 90 min. Take out the film, add it to toluene, heat under reflux, then add acetone, filter, and wash successively with acetone and ethanol, and dry to obtain modified PET.

[0006] Step B: Add dichloromethane, trifluoroacetic acid, and modified PET to a container, stir and then add a fatty acid eutectic phase change material, stir and then let it stand for defoaming to make a spinning solution, and then carry out electrospinning through an electrospinning machine. The voltage for electrospinning is 15 - 18 kV, the flow rate of the spinning solution is 2 - 3 mL / h, and wind up to obtain phase change energy storage fibers.

[0007] Preferably, in step B, the mass of the fatty acid eutectic phase change material is 60-100% of the mass of the modified PET.

[0008] Preferably, the preparation method of the fatty acid eutectic phase change material is as follows: Add fatty acid to a reaction vessel, keep it warm at 80-90 °C for 2-3 h, then place it in an ultrasonic instrument and ultrasonically treat it at 60-70 °C for 2-3 min, and cool to obtain the fatty acid eutectic phase change material. The fatty acid is any one or a combination of myristic acid, stearic acid, capric acid, and lauric acid.

[0009] Preferably, the preparation method of the graft monomer is as follows:

[0010] (1) Add ethanol, 2-methylallylamine with a molar ratio of (1-1.1):1, and benzaldehyde-based DOPO intermediate to a reaction vessel, heat to 60-70 °C, stir and react for 5-8 h, cool in an ice-water bath, precipitate, filter, and dry to obtain the methallyl DOPO intermediate. The reaction formula is as follows:

[0011]

[0012] (2) Add toluene and dichloromethane with a volume ratio of 1:(0.7-1), methallyl DOPO intermediate, fatty acyl chloride, and triethylamine with a molar ratio of 1:(1-1.3):(1-1.3) to a reaction vessel, react at room temperature for 6-10 h, rotary evaporate, wash with petroleum ether, and recrystallize the product with dichloromethane to obtain the graft monomer. The reaction formula is:

[0013]

[0014] Preferably, a phase change energy storage fabric made of phase change energy storage fibers.

[0015] (III) Beneficial technical effects: The present invention uses a graft monomer to carry out ultraviolet irradiation graft modification on polyethylene terephthalate PET, introduces an aliphatic alkyl long chain and a DOPO-containing phosphorus flame retardant structure into the PET matrix, and then electrospins with a fatty acid eutectic phase change material composed of capric acid, lauric acid, etc. The obtained phase change energy storage fibers exhibit different melting temperatures and melting enthalpy values and have good phase change heat storage performance. It has broad application prospects in aspects such as phase change heat storage fiber fabrics.

[0016] The PET of the present invention is grafted with a DOPO-containing phosphorus flame retardant structure, which significantly improves the flame retardant performance of PET fibers and exhibits a higher limiting oxygen index. At the same time, PET is grafted with an aliphatic alkyl long chain, which has good compatibility with the eutectic phase change materials of fatty acids composed of capric acid, lauric acid, etc. Moreover, the grafted aliphatic alkyl long chain forms an association and physical cross-linking of molecular chains with the alkyl long chain of fatty acids in the eutectic phase change materials, further improving the interfacial bonding force between the eutectic phase change materials and PET fibers, thereby reducing the adverse effects of the eutectic phase change materials on the mechanical properties of PET fibers, and enabling the PET fiber felt to maintain high tensile strength, elongation at break and mechanical properties. Detailed Embodiments

[0017] The following provides a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not intended to limit the present invention.

[0018] The preparation method of the benzaldehyde-based DOPO intermediate is as follows: Add 0.5 mol of terephthalaldehyde to a reaction vessel, dropwise add a 1,4-dioxane (15 mL) solution containing 0.55 mol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, react at 30 °C for 7 h, filter after cooling, and recrystallize the product with ethanol to obtain the benzaldehyde-based DOPO intermediate. The structural formula is:

[0019] Example 1

[0020] (1) Add 500 mL of ethanol, 60 mmol of 2-methylallylamine, and 60 mmol of the benzaldehyde-based DOPO intermediate to a reaction vessel, heat to 70 °C, stir and react for 5 h, cool in an ice-water bath, precipitate, filter, and dry to obtain the methallyl DOPO intermediate.

[0021] (2) Add 200 mL of toluene and 200 mL of dichloromethane, 50 mmol of the methallyl DOPO intermediate, 65 mmol of stearoyl chloride, and 65 mmol of triethylamine to a reaction vessel, react at room temperature for 6 h, rotary evaporate, wash with petroleum ether, and recrystallize the product with dichloromethane to obtain the graft monomer.

[0022] (3) Add 10 g of stearic acid, 10 g of capric acid, and 80 g of lauric acid to a reaction vessel, keep warm at 90 °C for 2 h, then place it in an ultrasonic instrument and ultrasonically treat at 70 °C for 2 min, and cool to obtain the fatty acid eutectic phase change material.

[0023] (4) Add an acetone solution of benzophenone with a mass concentration of 0.3 g / L to the reaction vessel. After stirring, add the polyethylene terephthalate film. Take out the film, dry to remove acetone, and then add the film to an ethanol solution of the graft monomer with a mass concentration of 30 g / L. Under a nitrogen atmosphere, irradiate with an ultraviolet lamp with a power of 800 w for 30 min to carry out the grafting reaction. Take out the film, add it to toluene, heat under reflux for 6 h, then add acetone, filter, and wash successively with acetone and ethanol, and dry to obtain modified PET.

[0024] (5) Add 450 mL of dichloromethane, 220 mL of trifluoroacetic acid, and 100 g of modified PET to the container. After stirring, add 60 g of the fatty acid eutectic phase change material, stir, and then stand for defoaming to prepare a spinning solution. Then carry out electrospinning with an electrospinning machine. The voltage for electrospinning is 18 kV, the flow rate of the spinning solution is 2 mL / h, and wind up to obtain the phase change energy storage fiber.

[0025] Example 2

[0026] (1) Add 600 mL of ethanol, 66 mmol of 2-methylallylamine, and 60 mmol of benzaldehyde-based DOPO intermediate to the reaction vessel, heat to 60 °C, stir and react for 8 h, cool in an ice-water bath, precipitate, filter, and dry to obtain the methylallyl DOPO intermediate.

[0027] (2) Add 200 mL of toluene and 140 mL of dichloromethane, 50 mmol of the methylallyl DOPO intermediate, 50 mmol of myristoyl chloride, and 50 mmol of triethylamine to the reaction vessel, react at room temperature for 10 h, rotary evaporate, wash with petroleum ether, and recrystallize the product with dichloromethane to obtain the graft monomer.

[0028] (3) Add 10 g of myristic acid, 10 g of capric acid, and 80 g of lauric acid to the reaction vessel, keep warm at 80 °C for 3 h, then place it in an ultrasonic instrument and ultrasonically treat at 60 °C for 3 min, and cool to obtain the fatty acid eutectic phase change material.

[0029] (4) Add an acetone solution of benzophenone with a mass concentration of 0.5 g / L to the reaction vessel. After stirring, add the polyethylene terephthalate film. Take out the film, dry to remove acetone, and then add the film to an ethanol solution of the graft monomer with a mass concentration of 65 g / L. Under a nitrogen atmosphere, irradiate with an ultraviolet lamp with a power of 800 w for 60 min to carry out the grafting reaction. Take out the film, add it to toluene, heat under reflux for 6 h, then add acetone, filter, and wash successively with acetone and ethanol, and dry to obtain modified PET.

[0030] (5) Add 450 mL of dichloromethane, 220 mL of trifluoroacetic acid, and 100 g of modified PET to a container. After stirring, add 70 g of fatty acid eutectic phase change material. After stirring, let it stand for defoaming to prepare a spinning solution. Then, perform electrospinning using an electrospinning machine. The voltage for electrospinning is 15 kV, the flow rate of the spinning solution is 2 mL / h, and wind it up to obtain phase change energy storage fibers.

[0031] Example 3

[0032] (1) Prepare the graft monomer according to the method of Example 1.

[0033] (2) Prepare the fatty acid eutectic phase change material according to the method of Example 1.

[0034] (3) Add an acetone solution of benzophenone with a mass concentration of 0.7 g / L to a reaction container. After stirring, add a polyethylene terephthalate film. Take out the film, dry to remove acetone, and then add the film to an ethanol solution of the graft monomer with a mass concentration of 100 g / L. Under a nitrogen atmosphere, irradiate it with an ultraviolet lamp with a power of 800 w for 90 min for grafting reaction. Take out the film, add it to toluene, heat under reflux for 6 h, then add acetone, filter, and wash successively with acetone and ethanol, and dry to obtain modified PET.

[0035] (4) Add 460 mL of dichloromethane, 230 mL of trifluoroacetic acid, and 100 g of modified PET to a container. After stirring, add 85 g of fatty acid eutectic phase change material. After stirring, let it stand for defoaming to prepare a spinning solution. Then, perform electrospinning using an electrospinning machine. The voltage for electrospinning is 18 kV, the flow rate of the spinning solution is 3 mL / h, and wind it up to obtain phase change energy storage fibers.

[0036] Example 4

[0037] (1) Prepare the graft monomer according to the method of Example 1.

[0038] (2) Prepare the fatty acid eutectic phase change material according to the method of Example 1.

[0039] (3) Add an acetone solution of benzophenone with a mass concentration of 1 g / L to a reaction container. After stirring, add a polyethylene terephthalate film. Take out the film, dry to remove acetone, and then add the film to an ethanol solution of the graft monomer with a mass concentration of 150 g / L. Under a nitrogen atmosphere, irradiate it with an ultraviolet lamp with a power of 800 w for 90 min for grafting reaction. Take out the film, add it to toluene, heat under reflux for 6 h, then add acetone, filter, and wash successively with acetone and ethanol, and dry to obtain modified PET.

[0040] (4) Add 460 mL of dichloromethane, 230 mL of trifluoroacetic acid, and 100 g of modified PET to a container. After stirring, add 100 g of fatty acid eutectic phase change material. After stirring, let it stand for defoaming to prepare a spinning solution. Then, perform electrospinning using an electrospinning machine. The voltage for electrospinning is 15 kV, the flow rate of the spinning solution is 3 mL / h, and wind it up to obtain phase change energy storage fibers.

[0041] Comparative Example 1

[0042] (1) Prepare the fatty acid eutectic phase change material according to the method of Example 1.

[0043] (2) Add 450 mL of dichloromethane, 220 mL of trifluoroacetic acid, and 100 g of polyethylene terephthalate to a container. After stirring, add 60 g of fatty acid eutectic phase change material. After stirring, let it stand for defoaming to prepare a spinning solution. Then, perform electrospinning using an electrospinning machine. The voltage for electrospinning is 18 kV, the flow rate of the spinning solution is 2 mL / h, and wind it up to obtain phase change energy storage fibers.

[0044] Comparative Example 2

[0045] (1) Prepare the methallyl DOPO intermediate according to the method of Example 1.

[0046] (2) Add an acetone solution of benzophenone with a mass concentration of 0.3 g / L to a reaction container. After stirring, add a polyethylene terephthalate film. Take out the film and dry it to remove acetone. Then, add the film to an ethanol solution of methallyl DOPO intermediate with a mass concentration of 30 g / L. Under a nitrogen atmosphere, irradiate it with an ultraviolet lamp with a power of 800 w for 30 min for grafting reaction. Take out the film, add it to toluene, heat it under reflux for 6 h, then add acetone, filter it, and wash it successively with acetone and ethanol, and dry it to obtain modified PET.

[0047] (3) Prepare the fatty acid eutectic phase change material according to the method of Example 1.

[0048] (4) Add 450 mL of dichloromethane, 220 mL of trifluoroacetic acid, and 100 g of modified PET to a container. After stirring, add 60 g of fatty acid eutectic phase change material. After stirring, let it stand for defoaming to prepare a spinning solution. Then, perform electrospinning using an electrospinning machine. The voltage for electrospinning is 18 kV, the flow rate of the spinning solution is 2 mL / h, and wind it up to obtain phase change energy storage fibers.

[0049] Pass the spinning solutions prepared in each example and comparative example through an electrospinning machine to electrospin them into fiber mats, make specimens of 10 cm × 1 cm, and test the tensile properties using an electronic universal testing machine. The clamping distance is 50 mm, the tensile rate is 5 mm / min, and the initial tension is 0.1 cN.

[0050] Test the limiting oxygen index of the fiber felt according to the method of GB / T 5454-1997. The larger the limiting oxygen index, the better the flame retardant performance.

[0051] Use a differential scanning calorimeter to test the phase change heat storage performance of the phase change energy storage fiber.

[0052] Table 1

[0053]

[0054]

[0055] As can be seen from Table 1, fatty acid eutectic phase change materials are added to the PET fibers in each example and comparative example. The fibers all exhibit different melting temperatures and melting enthalpy values, and have good phase change heat storage performance. However, the tensile strength, elongation at break, and limiting oxygen index of the PET fiber felts in Examples 1-4 are significantly higher than those in Comparative Example 1. This is because polyethylene terephthalate (PET) is modified by ultraviolet irradiation grafting of graft monomers, and aliphatic alkyl long chains are grafted in the PET matrix. There is good compatibility with the fatty acid eutectic phase change material composed of capric acid, lauric acid, etc. At the same time, the aliphatic alkyl long chains grafted on PET form an association effect and physical crosslinking of molecular chains with the alkyl long chains of fatty acids in the eutectic phase change material, further improving the interfacial bonding force between the eutectic phase change material and the PET fiber, thereby reducing the adverse effects of the eutectic phase change material on the mechanical properties of the PET fiber, making the PET fiber felt exhibit higher tensile strength and elongation at break. And after ultraviolet irradiation grafting of graft monomers, a large number of DOPO-containing phosphorus flame retardant structures are introduced into the PET matrix, significantly increasing the limiting oxygen index of the fiber and having better flame retardant performance.

[0056] Comparative Example 2 uses methylallyl DOPO intermediate Graft-modify PET, introduce a large number of DOPO-containing phosphorus flame retardant structures into the PET matrix, significantly increasing the limiting oxygen index of the fiber and having better flame retardant performance. However, PET does not contain aliphatic alkyl long chains, and the compatibility and interfacial bonding force with the fatty acid eutectic phase change material are relatively low. As a result, after adding the phase change material, the tensile strength and elongation at break of the PET fiber felt decrease significantly, and the mechanical properties become very poor.

[0057] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the technical concept scope of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A method for preparing a phase change energy storage fiber, characterized in that: The preparation method is: Step A, adding an acetone solution containing benzophenone to a reaction container, adding a polyethylene terephthalate film after stirring, taking out the film, drying it, then adding the film to an ethanol solution containing a grafting monomer, irradiating it under an ultraviolet lamp in a nitrogen atmosphere, and performing a grafting reaction for 30-90 minutes, taking out the film, adding it to toluene, heating it to reflux, then adding acetone, filtering it, washing it, and drying it to obtain a modified PET; The structural formula of the grafted monomer is: n is any integer between 13 and 17; Step B, adding dichloromethane, trifluoroacetic acid, and modified PET into a container, adding fatty acid eutectic phase change material after stirring, standing and degassing after stirring to prepare a spinning solution, and then spinning and winding through an electrostatic spinning machine to obtain a phase change energy storage fiber.

2. The method for preparing the phase change energy storage fiber according to claim 1, characterized in that: In the step A, the mass concentration of benzophenone in the acetone solution is 0.3-1 g / L; the mass concentration of the grafting monomer in the ethanol solution is 30-150 g / L.

3. The method for preparing the phase change energy storage fiber according to claim 1, characterized in that: In the step B, the mass of the fatty acid eutectic phase change material is 60-100% of the mass of the modified PET.

4. The method for preparing the phase change energy storage fiber according to claim 3, characterized in that: The preparation method of the fatty acid eutectic phase change material is as follows: add fatty acid into a reaction container, keep warm at 80-90° C. for 2-3 hours, then place in an ultrasonic instrument, perform ultrasonic treatment at 60-70° C. for 2-3 minutes, and cool to obtain the fatty acid eutectic phase change material.

5. The method for preparing the phase change energy storage fiber according to claim 4, characterized in that: The fatty acid is any one or a combination of myristic acid, stearic acid, capric acid and lauric acid.

6. The method for preparing the phase change energy storage fiber according to claim 1, characterized in that: The voltage during spinning in step B is 15-18 kV, and the flow rate of the spinning solution is 2-3 mL / h.

7. The method for preparing the phase change energy storage fiber according to claim 1, characterized in that: The preparation method of the grafted monomer is: (1) Add ethanol, 2-methylallylamine and benzaldehyde DOPO intermediate in a molar ratio of (1-1.1):1 to a reaction vessel, heat to 60-70° C., stir and react for 5-8 hours, cool in an ice water bath, precipitate, filter and dry to obtain a methylallyl DOPO intermediate; The structural formula of the benzaldehyde-based DOPO intermediate is (2) Add toluene and dichloromethane in a volume ratio of 1:(0.7-1), and methylallyl DOPO intermediate, fatty acid chloride and triethylamine in a molar ratio of 1:(1-1.3):(1-1.3) into a reaction container, react at room temperature for 6-10 hours, rotary evaporate, wash, and recrystallize to obtain a grafted monomer.

8. The method for preparing the phase change energy storage fiber according to claim 7, characterized in that: The structural formula of the fatty acid chloride is n is any integer between 13 and 17.

9. A fabric made of phase change energy storage fiber obtained by the preparation method according to any one of claims 1 to 8.

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