Highly insulating composite material and method for its production

Abstract

The application relates to the technical field of insulating materials, in particular to a high-insulation composite material and a preparation method thereof. The high-insulation composite material comprises a polyester fiber base material layer and a hydrophobic film layer; the preparation method of the high-insulation composite material comprises the following steps: spreading polyester fibers, then reinforcing by needling to obtain the polyester fiber base material layer, immersing the polyester fiber base material layer into a hydrophobic mixed solution, carrying out gradient drying after taking out, carrying out annealing treatment, cutting, and packaging to obtain the high-insulation composite material. The high-insulation composite material prepared by the application has good mechanical, hydrophobic and insulating properties, and has a good application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of insulating materials, and particularly relates to a high-insulation composite material and a preparation method thereof. BACKGROUND

[0002] The existing insulating material is usually obtained by mixing polyester fibers and low-melting-point polyester fibers, and the polyester fibers have good tensile force and elongation at break and are widely used in transformers, motors, generators and other electrical equipment requiring electrical insulation. However, the insulating property of pure polyester fibers as insulating materials is insufficient, and with the development of power cables, the requirements for insulating protective materials are becoming higher and higher. When the insulating material is used outdoors, it is often exposed to outdoor weather and may be subjected to rain, which may cause surface water and lead to the phenomenon of electric leakage or reduced insulating property.

[0003] Therefore, there is an urgent need for a material with good insulating property, waterproofness and mechanical property to solve the above problems. SUMMARY

[0004] The application aims to provide a high-insulation composite material and a preparation method thereof, and solve the above technical problems in the prior art.

[0005] In order to achieve the above-mentioned purpose, the application adopts the following technical scheme:

[0006] The application provides the following technical scheme:

[0007] In a first aspect, the application provides a high-insulation composite material, which comprises a polyester fiber base material layer and a hydrophobic film layer; the hydrophobic film layer is obtained by coating the polyester fiber base material layer with a hydrophobic mixture.

[0008] Preferably, the preparation method of the hydrophobic mixture comprises the following steps:

[0009] S1: Dissolve isophthaloyl chloride in butanone, then add it to a mixture containing octafluoro-1,6-hexanediol, 1H,1H-perfluoro-3,6,9-trioxafulvene-1-alcohol and triethylamine, react, cool to room temperature, filter, evaporate, obtain a solid, then heat the solid in a nitrogen atmosphere, and heat at a high temperature to obtain a fluorinated polyester; in the above process, the two hydroxyl groups of 1 part of octafluoro-1,6-hexanediol are replaced by 2 parts of chlorine atoms of isophthaloyl chloride, and then the other chlorine atom of isophthaloyl chloride replaces the hydroxyl group of 1H,1H-perfluoro-3,6,9-trioxafulvene-1-alcohol to obtain a fluorinated polyester; the solid oligomer is polymerized in a molten state, and secondary heat treatment promotes the formation of a higher molecular weight oligomer relative to the initial intermediate.

[0010] S2: adding PET and fluorinated polyester into 1,1,1,3,3,3-hexafluoro-2-propanol to obtain a polyester mixture, and then adding modified boron nitride nanosheets and modified halloysite nanotubes, and ultrasonicating and magnetically stirring to obtain a hydrophobic mixture.

[0011] Preferably, in S1, the reaction conditions are: the reaction temperature is 65-80℃, the reaction time is 2.5-3.5h; the amount ratio of isophthaloyl chloride, butanone, octafluoro-1,6-hexanediol, 1H,1H-perfluoro-3,6,9-trioxa-1-ol, and triethylamine is 10-20g:200-400mL:11.5-23g:8.3-16.6g:9.9-20g; the heating conditions are: the heating temperature is 145-155℃, the heating time is 6-8h; the temperature rising heating conditions are: the temperature rising heating temperature is 195-205℃, the temperature rising heating time is 4.5-5.5h.

[0012] Preferably, in S2, the amount ratio of PET, fluorinated polyester, 1,1,1,3,3,3-hexafluoro-2-propanol, modified boron nitride nanosheets, and modified halloysite nanotubes is 95-190g:5-10g:2.2-4.4L:0.5-1g:0.5-1g; the ultrasonicating and magnetically stirring time is 30-60min.

[0013] Preferably, the method for preparing the modified halloysite nanotubes comprises the following steps:

[0014] The halloysite nanotubes are dispersed in a mixture of anhydrous ethanol and ammonia water, ultrasonicated, then hexadecyltrimethoxysilane is added, magnetically stirred, centrifuged, washed, dried, ground, and the modified halloysite nanotubes are obtained.

[0015] Preferably, the amount ratio of the halloysite nanotubes, the mixture of anhydrous ethanol and ammonia water, and hexadecyltrimethoxysilane is 6-12g:100-200mL:300-600μL; the volume ratio of anhydrous ethanol to ammonia water in the mixture of anhydrous ethanol and ammonia water is 95:5; the ultrasonicating time is 30-50min; the magnetically stirring time is 2.5-3.5h; the drying conditions are: the drying temperature is 55-65℃, the drying time is 10-14h.

[0016] Preferably, the method for preparing the modified boron nitride comprises the following steps:

[0017] P1: dispersing boron nitride nanosheets in an aqueous hydrogen peroxide solution to obtain a 1wt% boron nitride dispersion, stirring and reacting, centrifuging, washing, and vacuum drying to constant weight to obtain hydroxylated boron nitride; dispersing the hydroxylated boron nitride in anhydrous ethanol, and ultrasonicating to obtain a 1wt% hydroxylated boron nitride dispersion.

[0018] P2: tridecafluorooctyltriethoxysilane is added into an aqueous ethanol solution to obtain a 3wt% silane solution, acetic acid is added to adjust the pH, and then 1wt% of a hydroxylated boron nitride dispersion liquid is added after magnetic stirring at room temperature, and the stirring treatment is continued at room temperature, followed by centrifugation, washing, and vacuum drying to a constant weight to obtain modified boron nitride.

[0019] Preferably, in P1, the mass fraction of the aqueous hydrogen peroxide solution is 30wt%; the stirring reaction conditions are that the stirring reaction temperature is 60-80℃ and the stirring reaction time is 18-24h; the washing method is that the washing is performed 3-5 times alternately with water and ethanol; the vacuum drying temperature is 60-80℃; and the ultrasonic treatment time is 20-40min.

[0020] Preferably, in P2, the volume ratio of ethanol to water in the aqueous ethanol solution is 9:1; the pH is adjusted to 4-5; the magnetic stirring time is 30-60min; the continuous stirring treatment time is 10-12h; the washing method is that the washing is performed 3-5 times with ethanol; and the vacuum drying temperature is 60-80℃.

[0021] Preferably, the thickness of the polyester fiber base material layer is 0.05-0.072mm, and the thickness of the hydrophobic film layer is 0.03-0.05mm.

[0022] Preferably, the thickness of the high-insulation composite material is 0.076-0.084mm, and the grammage is 88-100g / m 2 .

[0023] In a second aspect, the present application further provides a preparation method of a high-insulation composite material, comprising the following steps:

[0024] The polyester fibers are laid and then needle-punched to obtain a polyester fiber base material layer, the polyester fiber base material layer is immersed in a hydrophobic mixed solution, and then gradient drying, annealing treatment, slitting, and packaging are performed to obtain a high-insulation composite material.

[0025] Preferably, the immersion time is 30-50min; the gradient drying method is that the drying is performed at room temperature for 30min, at 40℃ for 1h, at 60℃ for 1h, and at 80℃ for 1h; and the annealing treatment method is that the annealing treatment is performed in a vacuum at 135-145℃ for 2.5-3.5h.

[0026] Preferably, the fineness of the polyester fibers is 3-5dtex, and the length is 40-50mm.

[0027] In summary, due to the adoption of the above technical solutions, the present application has the following beneficial effects:

[0028] 1. The high insulation composite material prepared by the present application comprises a polyester fiber substrate layer and a hydrophobic film layer. The polyester fiber substrate layer is made of polyester fiber, which is high in temperature resistance, strength and insulation. The hydrophobic film layer is obtained by adding fluorinated polyester to PET and annealing to make the outermost fluorinated groups migrate and reorient, thereby reducing the surface energy of the film and promoting the interface fusion of the coating and the fiber to improve the coating firmness. The hydrophobic film layer inhibits the charge injection of deep interface traps and accelerates the charge dissipation, and at the same time forms a micro-nano layered surface structure, which cooperates with the polyester fiber substrate layer to endow the high insulation composite material with high surface flashover strength and super-hydrophobic surface.

[0029] 2. The hydrophobic film layer prepared by the present application introduces perfluoro segments to reduce the surface energy and dielectric constant of the hydrophobic film layer and improve the insulation; the modified boron nitride obtained by hydrogen-hydroxyl grafting perfluoro octyl silane has good dispersibility, hydrophobicity and thermal conductivity, which disperses the transmission path of electrons, improves the dielectric breakdown voltage, and the modified halloysite nanotube also improves the compatibility in the polymer matrix. By compounding the sheet-like modified boron nitride and the tubular modified halloysite nanotube, a more complex and dense three-dimensional network barrier is constructed in the polymer, which further inhibits the migration and accumulation of charges, improves the surface flashover strength of the composite material, and creates the required micro-nano level synergistic structure of the super-hydrophobic surface, endowing the composite material with high surface flashover strength and super-hydrophobic surface; a more dense network is formed in the polymer matrix, providing high thermal stability and high dielectric breakdown voltage, and synergistically enhancing the mechanical strength, hydrophobicity and insulation of the coating. BRIEF DESCRIPTION OF DRAWINGS

[0030] 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.

[0031] Figure 1 is the tensile strength histogram of the high insulation composite material of the present application;

[0032] Figure 2 is the elongation histogram of the high insulation composite material of the present application;

[0033] Figure 3 is the dielectric breakdown strength line graph of the high insulation composite material of the present application. DETAILED DESCRIPTION

[0034] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0035] The substances and sources involved in the following examples and comparative examples are shown in Table 1:

[0036] Table 1

[0037]

[0038] Example 1: This example discloses a preparation method of modified halloysite nanotubes, comprising the following steps:

[0039] 9 g of halloysite nanotubes were dispersed in a mixture of 150 mL of anhydrous ethanol and ammonia water with a volume ratio of 95:5, ultrasonic treatment was performed for 40 min, then 450 μL of hexadecyltrimethoxysilane was added, magnetic stirring was performed for 3 h, centrifugation, washing, and drying at 60℃ for 12 h, grinding, to obtain modified halloysite nanotubes.

[0040] Example 2: This example discloses a preparation method of modified boron nitride, comprising the following steps:

[0041] P1: Disperse boron nitride nanosheets in 30wt% hydrogen peroxide aqueous solution to obtain a 1wt% boron nitride dispersion, then stir at 70℃ for 21 h, centrifuge, wash with water and ethanol alternately for 4 times, then vacuum dry at 70℃ to obtain hydroxylated boron nitride; disperse the hydroxylated boron nitride in anhydrous ethanol, ultrasonic treatment for 30 min to obtain a 1wt% hydroxylated boron nitride dispersion;

[0042] P2: Add tridecafluorooctyltriethoxysilane to an ethanol aqueous solution with a volume ratio of ethanol to water of 9:1 to obtain a 3wt% silane solution, then add acetic acid to adjust the pH to 4-5, magnetically stir at room temperature for 30-60 min, then add 1wt% of the hydroxylated boron nitride dispersion, continue to stir at room temperature for 10-12 h, centrifuge, wash with ethanol for 3-5 times, and finally vacuum dry at 60-80℃ to constant weight to obtain modified boron nitride.

[0043] Example 3: This example discloses a preparation method of a hydrophobic mixture, comprising the following steps:

[0044] S1 : Dissolve 15 g of isophthaloyl dichloride in 300 mL of butanone, then add to a mixture containing 16 g of octafluoro-1,6-hexanediol, 12 g of 1 H,1 H-perfluoro-3,6,9- trioxaheptan-1 -ol and 15 g of triethylamine, react at 72 °C for 3 h, after cooling to room temperature, filter, evaporate, obtain a solid, then heat the solid in a nitrogen atmosphere at 150 °C for 7 h, then at 200 °C for 5 h, obtain a fluorinated polyester.

[0045] S2: Add 150 g of PET and 7.5 g of fluorinated polyester to 3.3 L of 1,1,1,3,3,3-hexafluoro-2-propanol to obtain a polyester mixture, then add 0.75 g of modified boron nitride nanosheets and 0.75 g of modified halloysite nanotubes, ultrasonic and magnetic stirring for 45 min to obtain a hydrophobic mixture.

[0046] Example 4: This example discloses a method for preparing a hydrophobic mixture, comprising the following steps:

[0047] S1 : Dissolve 15 g of isophthaloyl dichloride in 300 mL of butanone, then add to a mixture containing 16 g of octafluoro-1,6-hexanediol, 12 g of 1 H,1 H-perfluoro-3,6,9- trioxaheptan-1 -ol and 15 g of triethylamine, react at 72 °C for 3 h, after cooling to room temperature, filter, evaporate, obtain a solid, then heat the solid in a nitrogen atmosphere at 150 °C for 7 h, then at 200 °C for 5 h, obtain a fluorinated polyester.

[0048] S2: Add 150 g of PET and 7.5 g of fluorinated polyester to 3.3 L of 1,1,1,3,3,3-hexafluoro-2-propanol to obtain a polyester mixture, then add 0.75 g of modified boron nitride nanosheets and 0.75 g of modified halloysite nanotubes, ultrasonic and magnetic stirring for 45 min to obtain a hydrophobic mixture.

[0049] Example 5: This example discloses a method for preparing a hydrophobic mixture, comprising the following steps:

[0050] S1 : Dissolve 15 g of isophthaloyl dichloride in 300 mL of butanone, then add to a mixture containing 16 g of octafluoro-1,6-hexanediol, 12 g of 1 H,1 H-perfluoro-3,6,9- trioxaheptan-1 -ol and 15 g of triethylamine, react at 72 °C for 3 h, after cooling to room temperature, filter, evaporate, obtain a solid, then heat the solid in a nitrogen atmosphere at 150 °C for 7 h, then at 200 °C for 5 h, obtain a fluorinated polyester.

[0051] S2: 95 g of PET and 10 g of fluorinated polyester were added into 2.2 L of 1,1,1,3,3,3-hexafluoro-2-propanol to obtain a polyester mixed solution, and then 1 g of modified boron nitride nanosheet and 0.5 g of modified halloysite nanotube were added, ultrasonic and magnetic stirring for 60 min to obtain a hydrophobic mixed solution.

[0052] Example 6: This example discloses a preparation method of a high insulation composite material, comprising the following steps:

[0053] The polyester fiber was laid and then needle punched to obtain a polyester fiber base material layer, the polyester fiber base material layer was immersed in the hydrophobic mixed solution prepared in Example 3 for 40 min, and then gradient drying was performed after taking out, room temperature drying for 30 min, drying at 40℃ for 1 h, drying at 60℃ for 1 h, drying at 80℃ for 1 h, and finally annealing treatment at 140℃ in vacuum for 3 h, slitting, packaging, and obtaining a high insulation composite material.

[0054] Example 7: This example discloses a preparation method of a high insulation composite material, comprising the following steps:

[0055] The polyester fiber was laid and then needle punched to obtain a polyester fiber base material layer, the polyester fiber base material layer was immersed in the hydrophobic mixed solution prepared in Example 4 for 30 min, and then gradient drying was performed after taking out, room temperature drying for 30 min, drying at 40℃ for 1 h, drying at 60℃ for 1 h, drying at 80℃ for 1 h, and finally annealing treatment at 145℃ in vacuum for 2.5 h, slitting, packaging, and obtaining a high insulation composite material.

[0056] Example 8: This example discloses a preparation method of a high insulation composite material, comprising the following steps:

[0057] The polyester fiber was laid and then needle punched to obtain a polyester fiber base material layer, the polyester fiber base material layer was immersed in the hydrophobic mixed solution prepared in Example 5 for 50 min, and then gradient drying was performed after taking out, room temperature drying for 30 min, drying at 40℃ for 1 h, drying at 60℃ for 1 h, drying at 80℃ for 1 h, and finally annealing treatment at 135℃ in vacuum for 3.5 h, slitting, packaging, and obtaining a high insulation composite material.

[0058] Comparative Example 1:

[0059] Comparative Example 1 and Example 6 are compared, and in the process of preparing the high insulation composite material, Comparative Example 1 does not have a hydrophobic film layer, and other conditions are unchanged.

[0060] Comparative Example 2:

[0061] Comparative Example 2 and Example 6 are compared, and in the process of preparing the high insulation composite material, Comparative Example 2 does not add modified boron nitride in the hydrophobic film layer, and other conditions are unchanged.

[0062] Comparative Example 3:

[0063] Comparative Example 3 is compared with Example 6, in the process of preparing high insulation composite material, no modified halloysite nanotubes are added in the hydrophobic film layer, and other conditions are unchanged.

[0064] Comparative Example 4:

[0065] Comparative Example 4 is compared with Example 6, in the process of preparing high insulation composite material, no fluorinated polyester is added in the hydrophobic film layer, and other conditions are unchanged.

[0066] The properties of the high insulation composite materials prepared in Examples 6-8 and Comparative Examples 1-4 are tested, and the test results are shown in Table 2:

[0067] Table 2

[0068]

[0069] According to Table 2 and from Examples 6-8 and Comparative Examples 1-4, the high insulation composite material prepared in Example 6 has good mechanical properties, hydrophobicity and insulation. As can be seen from the comparison of Comparative Examples 1-4 and Examples 6-8, using an uncombined hydrophobic film layer, no modified boron nitride in the hydrophobic film layer, no modified halloysite nanotubes in the hydrophobic film layer, and no fluorinated polyester in the hydrophobic film layer will reduce the mechanical properties, hydrophobicity and insulation of the high insulation composite material. The high insulation composite material obtained by the method of the present application has the best performance, and the effect is not as obvious as the present application when other methods are used instead.

[0070] The above description is only a preferred embodiment of the present application, but the protection scope of the present application is not limited thereto. Any skilled person in the art can make equivalent substitutions or changes within the technical scope disclosed in the present application according to the technical solution and inventive concept of the present application, which should be covered within the protection scope of the present application.

[0071] The preferred embodiments of the present application disclosed above are only used to help explain the present application. The preferred embodiments do not describe all the details, and the present application is not limited to the specific embodiments. Obviously, many modifications and changes can be made according to the content of the present application. The embodiments are selected and described in the present specification in order to better explain the principles and practical applications of the present application, so that those skilled in the art can well understand and utilize the present application. The present application is limited by the claims and their entire scope and equivalents.

Claims

1. A high insulation composite material, characterized by, The high insulation composite material comprises a polyester fiber base material layer and a hydrophobic film layer; the hydrophobic film layer is obtained by coating the polyester fiber base material layer with a hydrophobic mixed solution; The preparation method of the hydrophobic mixed solution comprises the following steps: S1: Dissolve isophthaloyl chloride in butanone, then add to a mixture containing octafluoro-1,6-hexanediol, 1H,1H-perfluoro-3,6,9-trioxa-1-heptanol and triethylamine, react, cool to room temperature, filter, evaporate to obtain a solid, then heat the solid in a nitrogen atmosphere, and heat at a temperature to obtain fluorinated polyester; S2: Add polyethylene terephthalate and fluorinated polyester to 1,1,1,3,3,3-hexafluoro-2-propanol to obtain a polyester mixed solution, then add modified boron nitride nanosheets and modified halloysite nanotubes, and after ultrasonic treatment and magnetic stirring, obtain a hydrophobic mixed solution; the preparation method of the modified halloysite nanotubes comprises the following steps: Disperse halloysite nanotubes in a mixture of anhydrous ethanol and ammonia water, ultrasonic treat, then add hexadecyltrimethoxysilane, magnetically stir, centrifuge, wash, dry, grind, and obtain modified halloysite nanotubes; the preparation method of the modified boron nitride comprises the following steps: P1: Disperse boron nitride nanosheets in an aqueous hydrogen peroxide solution to obtain a 1wt% boron nitride dispersion, stir and react, centrifuge, wash, and vacuum dry to constant weight to obtain hydroxylated boron nitride; disperse the hydroxylated boron nitride in anhydrous ethanol, ultrasonic treat, and obtain a 1wt% hydroxylated boron nitride dispersion; P2: Add tridecafluorooctyltriethoxysilane to an aqueous ethanol solution to obtain a 3wt% silane solution, then add acetic acid to adjust the pH, magnetically stir at room temperature, then add the 1wt% hydroxylated boron nitride dispersion, continue to stir at room temperature, centrifuge, wash, and vacuum dry to constant weight to obtain modified boron nitride.

2. The high insulation composite material according to claim 1, characterized in that, In S1, the reaction conditions are as follows: the reaction temperature is 65-80℃, the reaction time is 2.5-3.5h, the amount ratio of isophthaloyl chloride, butanone, octafluoro-1,6-hexanediol, 1H,1H-perfluoro-3,6,9-trioxa-1-heptanol and triethylamine is 10-20g:200-400mL:11.5-23g:8.3-16.6g:9.9-20g, the heating conditions are as follows: the heating temperature is 145-155℃, the heating time is 6-8h, the temperature rising heating conditions are as follows: the temperature rising heating temperature is 195-205℃, the temperature rising heating time is 4.5-5.5h; in S2, the amount ratio of PET, fluorinated polyester, 1,1,1,3,3,3-hexafluoro-2-propanol, modified boron nitride nanosheets and modified halloysite nanotubes is 95-190g:5-10g:2.2-4.4L:0.5-1g:0.5-1g, and the ultrasonic treatment and magnetic stirring time is 30-60min.

3. The high insulation composite material of claim 1, wherein, The amount ratio of the mixture of the halloysite nanotubes, anhydrous ethanol and ammonia water, and the amount of hexadecyl trimethoxysilane is 6-12 g: 100-200 mL: 300-600 μL; the volume ratio of anhydrous ethanol and ammonia water in the mixture of anhydrous ethanol and ammonia water is 95:5; the ultrasonic treatment time is 30-50 min; the magnetic stirring time is 2.5-3.5 h; the drying conditions are that the drying temperature is 55-65℃, and the drying time is 10-14 h.

4. The high insulation composite material of claim 1, wherein, In the P1, the mass fraction of the hydrogen peroxide aqueous solution is 30 wt%; the stirring reaction conditions are that the stirring reaction temperature is 60-80℃, and the stirring reaction time is 18-24 h; the washing method is that the water and ethanol are alternately washed for 3-5 times; the vacuum drying temperature is 60-80℃; and the ultrasonic treatment time is 20-40 min.

5. The high insulation composite material of claim 1, wherein, In the P2, the volume ratio of ethanol and water in the ethanol aqueous solution is 9:1; the pH is adjusted to 4-5; the magnetic stirring time is 30-60 min; the continuous stirring treatment time is 10-12 h; the washing method is that the ethanol is washed for 3-5 times; and the vacuum drying temperature is 60-80℃.

6. The high insulation composite material of claim 1, wherein, The thickness of the polyester fiber base material layer is 0.05-0.072 mm, and the thickness of the hydrophobic film layer is 0.03-0.05 mm; the thickness of the high insulation composite material is 0.076-0.084 mm, and the grammage is 80-100 g / m 2 .

7. A process for the preparation of a high insulation composite material according to any one of claims 1-6, characterized in that, The method comprises the following steps: The polyester fiber is laid and then reinforced by needling to obtain a polyester fiber base layer, the polyester fiber base layer is immersed in the hydrophobic mixture, and after being taken out, gradient drying, annealing treatment, slitting, and packaging are performed to obtain the high-insulation composite material.

8. The method for preparing the high-insulation composite material according to claim 7, characterized in that, The immersion time is 30-50 min; the gradient drying method is that the gradient drying is performed at room temperature for 30 min, at 40℃ for 1 h, at 60℃ for 1 h, and at 80℃ for 1 h; the annealing treatment method is that the annealing treatment is performed in vacuum at 135-145℃ for 2.5-3.5 h; the fineness of the polyester fiber is 3-5 dtex, and the length is 40-50 mm.

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