A pvdf profile and a process for its preparation

Abstract

The application discloses PVDF profile and a preparation process thereof, and belongs to the technical field of plastic preparation technology. The PVDF profile comprises polyvinylidene fluoride and a filler. The filler is prepared by the following steps: 4-bromobenzocyclobutene and dimethyl chlorosilane are used as raw materials to react, benzocyclobutene is grafted on a silane monomer, 2-adamantane-4-bromo-1-(2, 2, 2-trifluoroethoxy) benzene and triethoxy ethylene silane are used as raw materials to graft adamantane and trifluoroethyl on an ethylene silane monomer, the grafted silane monomer and the grafted ethylene silane monomer are used to prepare modified silane monomers with vinyl, cyclobutenyl, adamantane and trifluoroethyl, and finally, nanometer silicon dioxide with a vinyl surface is copolymerized to obtain the modified silane monomers. In the application, the nanometer silicon dioxide filler is surface modified to introduce adamantane structure and a trifluoroethyl group, the dispersion compatibility of the nanometer silicon dioxide filler with the PVDF is improved, and the forming shrinkage of the nanometer silicon dioxide filler is effectively reduced.

Description

Technical Field

[0001] This invention relates to the field of plastic preparation technology, specifically to a PVDF profile and its preparation process. Background Technology

[0002] PVDF, short for polyvinylidene fluoride, is a polymer material that can be molded using a high-temperature extrusion process. Its crystallinity is between 65% and 78%, and its density is 1.77-1.8 g / cm³. 3 With a melting point as high as 172℃, a heat distortion temperature between 112-145℃, and a continuous working temperature range of -40℃ to 150℃, PVDF material possesses a series of key advantages due to its unique chemical structure and excellent physical properties. The special molecular structure in which CH2 and CF2 alternate in its polymer chain gives PVDF both the excellent processing performance of polyethylene and the excellent chemical resistance close to that of polytetrafluoroethylene. PVDF contains no UV stabilizers, heat stabilizers, softeners, lubricants, or flame retardant additives, thus possessing extremely high purity and stability. PVDF inherently exhibits excellent flame retardant properties, with an oxygen index of 46%, easily achieving the UL94 V0 flame retardant rating without any added flame retardants. PVDF also demonstrates excellent chemical resistance, reacting almost entirely with no media and exhibiting high chemical inertness to most acids, alkalis, salts, and many organic solvents. Its smooth surface makes it difficult for materials to adhere, making it one of the best materials for pumps, valves, pipes, pipe fittings, storage tanks, and heat exchangers in petrochemical equipment fluid handling systems, whether as a whole or as linings. Compared to other plastic materials, PVDF possesses higher tensile strength, impact resistance, and abrasion resistance, maintaining good rigidity and toughness even at low temperatures. Furthermore, PVDF is an excellent insulating material with a low dielectric constant and loss factor, making it suitable for insulation protection in electronics, power, and other fields.

[0003] Based on the aforementioned advantages of PVDF, it is widely used in the fields of sheet metal, rods, pipes, and welding materials. However, PVDF has a large forming shrinkage rate, making it difficult to maintain stable dimensional accuracy when forming sheet metal, rods, pipes, or welding materials. Adding fillers can reduce its shrinkage rate, but the chemical inertness of PVDF means that ordinary fillers are difficult to disperse and be compatible with it well. Summary of the Invention

[0004] To address the above problems, this invention provides a PVDF profile and its manufacturing process.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A PVDF profile includes polyvinylidene fluoride and filler, wherein the filler is prepared by the following steps:

[0007] (1) Weigh 4-bromobenzocyclobutene and dissolve it in tetrahydrofuran solvent. Add magnesium powder and slowly add dimethylchlorosilane under stirring. After the addition is complete, continue stirring for 10-20 h. After the reaction is complete, centrifuge to separate the precipitate and remove the solvent under reduced pressure to obtain product A.

[0008] (2) Under a protective atmosphere, triethoxyethylene silane was dissolved in tetrahydrofuran solvent, iodine and magnesium powder were added, and 2-adamantane-4-bromo-1-(2,2,2-trifluoroethoxy)benzene was slowly added under stirring. After the addition was completed, the reaction was stirred for 5-10 h. After the reaction was completed, cyclohexane was added to dilute the reaction system, the precipitate was separated by centrifugation, and the solvent was removed by vacuum distillation to obtain product B. Product A was dissolved in toluene solvent, and product B and perfluorotriphenylborone were added under stirring. The reaction was stirred for 2-5 h at room temperature. After the reaction was completed, the product was concentrated under vacuum, purified by chromatography to remove unreacted reactants, and the solvent was removed by vacuum distillation to obtain product C.

[0009] (3) The nano-silica is surface-treated with a vinylsilane coupling agent to obtain a precursor product; the C product is dissolved in a mestriylbenzene solvent, the precursor product is added and stirred and dispersed, stirred and refluxed at 150-160℃ for 2-8h, cooled and separated into precipitates, and after the solvent in the precipitate is evaporated, the temperature is raised to 210-250℃ under a protective atmosphere and kept at the temperature for 1-3h, and cooled to obtain the product.

[0010] In some preferred embodiments, the PVDF profile may also be blended with other polymers, such as polytetrafluoroethylene, polyoxymethylene, polyimide, polyetherimide, polyphenylene ester, or a mixture thereof.

[0011] In some preferred embodiments, the polyvinylidene fluoride has a weight-average molecular weight of 100,000 to 1,000,000.

[0012] In some preferred embodiments, the mass ratio of polyvinylidene fluoride to the filler is (6-10):1.

[0013] In some preferred embodiments, the mass ratio of 4-bromobenzocyclobutene to magnesium powder and dimethylchlorosilane in step (1) is 10:(1.8-2):(10-11).

[0014] In some preferred embodiments, the mass ratio of the triethoxyethylene silane to the iodine, the magnesium powder, and the 2-adamantane-4-bromo-1-(2,2,2-trifluoroethoxy)benzene in step (2) is 10:(0.13-0.15):(1.34-1.52):(14-16).

[0015] In some preferred embodiments, the mass ratio of product A to product B and perfluorotriphenylborone in step (2) is 10:(13-15):(0.07-0.09).

[0016] In some preferred embodiments, the particle size of the nano-silica in step (3) is 100-1000 nm.

[0017] In some preferred embodiments, the vinyl silane coupling agent in step (3) is vinyltrimethoxysilane, vinylmethoxydiethoxysilane, vinyltriethoxysilane, vinylethoxydiisopropoxysilane, vinyltriisopropoxysilane, γ-methacryloyloxypropyltrimethoxysilane, or γ-methacryloyloxypropyltriisopropoxysilane.

[0018] In some preferred embodiments, the mass ratio of the C product to the precursor product in step (3) is (1-2.4):1.

[0019] In some preferred embodiments, the PVDF profiles are used in the form of plates, rods, tubes or welding materials, and are formed by extrusion or molding.

[0020] Another object of the present invention is to provide a manufacturing process for the PVDF profile, specifically including the following steps:

[0021] S1. Prepare the packing material for later use;

[0022] S2. The polyvinylidene fluoride is mixed with the filler and then extruded and granulated at 250-300°C to obtain the final product.

[0023] The beneficial effects of this invention are as follows:

[0024] To address the issues of high shrinkage and unstable dimensional accuracy of PVDF profiles in existing technologies, this invention provides a PVDF profile with low forming shrinkage. This profile is created by surface modification of nano-silica fillers, introducing adamantane structures and trifluoroethyl groups to improve its dispersion compatibility with PVDF and effectively reduce its forming shrinkage. Specifically, this invention uses 4-bromobenzocyclobutene and dimethylchlorosilane as raw materials to react, grafting benzocyclobutene onto the silane monomer, and using triethoxyethylene silane and 2-adamantane-4-bromo-1- Using (2,2,2-trifluoroethoxy)benzene as a raw material, adamantane and trifluoroethyl are grafted onto ethylene silane monomers. The grafted silane monomers are then reacted with the grafted ethylene silane monomers to obtain modified silane monomers with vinyl, cyclobutenyl, adamantane, and trifluoroethyl groups. Finally, these modified silane monomers are copolymerized with vinyl-surface-modified nano-silica to chemically bond a layer of organosilanes onto the surface of the nano-silica. This process improves the affinity and compatibility between the filler and the resin, reduces the molding shrinkage of the resin, and the introduction of adamantane structural groups can also improve the mechanical properties of the resin. Detailed Implementation

[0025] The present invention will be further described in conjunction with the following embodiments. Example 1

[0026] A PVDF profile, composed of polyvinylidene fluoride and fillers, is manufactured using the following steps:

[0027] S1. Preparation of the packing material

[0028] (1) Weigh 4-bromobenzocyclobutene and dissolve it in tetrahydrofuran solvent. Add magnesium powder and slowly add dimethylchlorosilane under stirring. After the addition is complete, continue stirring and react for 14 hours. After the reaction is complete, centrifuge to separate the precipitate and remove the solvent under reduced pressure to obtain product A. The mass ratio of 4-bromobenzocyclobutene to magnesium powder and dimethylchlorosilane is 10:1.9:10.7.

[0029] (2) Under a nitrogen protective atmosphere, triethoxyethylene silane was dissolved in tetrahydrofuran solvent, iodine and magnesium powder were added, and 2-adamantane-4-bromo-1-(2,2,2-trifluoroethoxy)benzene (CAS No. 929000-50-0) was slowly added under stirring. After the addition was completed, the reaction was stirred for 8 hours. After the reaction was completed, cyclohexane of the same volume as the reaction system was added for dilution, the precipitate was separated by centrifugation, and the solvent was removed by vacuum distillation to obtain product B. Product A was dissolved in toluene solvent, and product B and perfluorotriphenylborone were added under stirring. The reaction was continued with stirring at room temperature for 3 hours. After the reaction was completed, the mixture was concentrated under reduced pressure and injected into a chromatographic column (500-mesh silica gel). Purification was performed using n-hexane as the mobile phase to remove unreacted reactants. After removing the solvent under reduced pressure, product C was obtained. The mass ratio of the triethoxyethylene silane to the iodine, magnesium powder, and 2-adamantane-4-bromo-1-(2,2,2-trifluoroethoxy)benzene was 10:0.14:1.45:14.9; the mass ratio of product A to product B and perfluorotriphenylborone was 10:14.2:0.08.

[0030] (3) Disperse nano-silica in an ethanol-water solution of vinyltrimethoxysilane with a concentration of 0.1 mol / L (v / v=9 / 1), stir for 4 h, separate the precipitate, wash with ethanol and deionized water, and dry to obtain the precursor product; dissolve the C product in mesitylene solvent, add the precursor product and stir to disperse, stir and reflux at 160 °C for 5 h, cool and separate the precipitate, wait for the solvent in the precipitate to evaporate, heat to 240 °C under a protective atmosphere and keep at the temperature for 1.5 h, cool to obtain the filler; wherein, the average particle size of the nano-silica is 400 nm; the mass ratio of the C product to the precursor product is 1.7:1;

[0031] S2. The polyvinylidene fluoride is mixed with the filler and then extruded and granulated at 270°C to obtain the product. The weight-average molecular weight of the polyvinylidene fluoride is 450,000. The mass ratio of the polyvinylidene fluoride to the filler is 7:1. Example 2

[0032] A PVDF profile, composed of polyvinylidene fluoride and fillers, is manufactured using the following steps:

[0033] S1. Preparation of the packing material

[0034] (1) Weigh 4-bromobenzocyclobutene and dissolve it in tetrahydrofuran solvent. Add magnesium powder and slowly add dimethylchlorosilane under stirring. After the addition is complete, continue stirring and react for 14 hours. After the reaction is complete, centrifuge to separate the precipitate and remove the solvent under reduced pressure to obtain product A. The mass ratio of 4-bromobenzocyclobutene to magnesium powder and dimethylchlorosilane is 10:1.9:10.7.

[0035] (2) Under a nitrogen protective atmosphere, triethoxyethylene silane was dissolved in tetrahydrofuran solvent, iodine and magnesium powder were added, and 2-(1-adamantyl)-4-bromoanisole (CAS No. 104224-63-7) was slowly added under stirring. After the addition was completed, the reaction was stirred for 8 hours. After the reaction was completed, cyclohexane of the same volume as the reaction system was added to dilute it. The precipitate was separated by centrifugation, and the solvent was removed by vacuum distillation to obtain product B. Product A was dissolved in toluene solvent, and product B and perfluorotriphenylborone were added under stirring. The reaction was continued with stirring at room temperature for 3 hours. After the reaction was completed, the mixture was concentrated under reduced pressure and injected into a chromatographic column (500-mesh silica gel). Purification was performed using n-hexane as the mobile phase to remove unreacted reactants. After removing the solvent under reduced pressure, product C was obtained. The mass ratio of the triethoxyethylene silane to the iodine, magnesium powder, and 2-(1-adamantyl)-4-bromoanisole was 10:0.14:1.45:14.9; the mass ratio of product A to product B and perfluorotriphenylborone was 10:14.2:0.08.

[0036] (3) Disperse nano-silica in an ethanol-water solution of vinyltrimethoxysilane with a concentration of 0.1 mol / L (v / v=9 / 1), stir for 4 h, separate the precipitate, wash with ethanol and deionized water, and dry to obtain the precursor product; dissolve the C product in mesitylene solvent, add the precursor product and stir to disperse, stir and reflux at 160 °C for 5 h, cool and separate the precipitate, wait for the solvent in the precipitate to evaporate, heat to 240 °C under a protective atmosphere and keep at the temperature for 1.5 h, cool to obtain the filler; wherein, the average particle size of the nano-silica is 400 nm; the mass ratio of the C product to the precursor product is 1.7:1;

[0037] S2. The polyvinylidene fluoride is mixed with the filler and then extruded and granulated at 270°C to obtain the product. The weight-average molecular weight of the polyvinylidene fluoride is 450,000. The mass ratio of the polyvinylidene fluoride to the filler is 7:1. Example 3

[0038] A PVDF profile, composed of polyvinylidene fluoride and fillers, is manufactured using the following steps:

[0039] S1. Preparation of the packing material

[0040] (1) Weigh 4-bromobenzocyclobutene and dissolve it in tetrahydrofuran solvent. Add magnesium powder and slowly add dimethylchlorosilane under stirring. After the addition is complete, continue stirring and react for 14 hours. After the reaction is complete, centrifuge to separate the precipitate and remove the solvent under reduced pressure to obtain product A. The mass ratio of 4-bromobenzocyclobutene to magnesium powder and dimethylchlorosilane is 10:1.9:10.7.

[0041] (2) Under a nitrogen protective atmosphere, triethoxyethylene silane was dissolved in tetrahydrofuran solvent, iodine and magnesium powder were added, and 1-bromo-4-(2,2,2-trifluoro-ethoxy)benzene (CAS No. 106854-77-7) was slowly added under stirring. After the addition was completed, the reaction was stirred for 8 hours. After the reaction was completed, cyclohexane of the same volume as the reaction system was added to dilute it. The precipitate was separated by centrifugation, and the solvent was removed by vacuum distillation to obtain product B. Product A was dissolved in toluene solvent, and product B and perfluorotriphenylborone were added under stirring. The reaction was continued with stirring at room temperature for 3 hours. After the reaction was completed, the mixture was concentrated under reduced pressure and injected into a chromatographic column (500-mesh silica gel). Purification was performed using n-hexane as the mobile phase to remove unreacted reactants. After removing the solvent under reduced pressure, product C was obtained. The mass ratio of the triethoxyethylene silane to the iodine, magnesium powder, and 1-bromo-4-(2,2,2-trifluoro-ethoxy)benzene was 10:0.14:1.45:14.9; the mass ratio of product A to product B and perfluorotriphenylborone was 10:14.2:0.08.

[0042] (3) Disperse nano-silica in an ethanol-water solution of vinyltrimethoxysilane with a concentration of 0.1 mol / L (v / v=9 / 1), stir for 4 h, separate the precipitate, wash with ethanol and deionized water, and dry to obtain the precursor product; dissolve the C product in mesitylene solvent, add the precursor product and stir to disperse, stir and reflux at 160 °C for 5 h, cool and separate the precipitate, wait for the solvent in the precipitate to evaporate, heat to 240 °C under a protective atmosphere and keep at the temperature for 1.5 h, cool to obtain the filler; wherein, the average particle size of the nano-silica is 400 nm; the mass ratio of the C product to the precursor product is 1.7:1;

[0043] S2. The polyvinylidene fluoride is mixed with the filler and then extruded and granulated at 270°C to obtain the product. The weight-average molecular weight of the polyvinylidene fluoride is 450,000. The mass ratio of the polyvinylidene fluoride to the filler is 7:1. Example 4

[0044] A PVDF profile is composed of polyvinylidene fluoride and filler. The preparation process is as follows: polyvinylidene fluoride is mixed with nano-silica filler and then extruded and granulated at 270°C. The weight-average molecular weight of the polyvinylidene fluoride is 450,000. The mass ratio of polyvinylidene fluoride to nano-silica filler is 7:1.

[0045] Using unfilled polyvinylidene fluoride (PVDF) as a control, the shrinkage rate and mechanical properties of the PVDF profiles described in Examples 1-4 were tested. Shrinkage rate testing was conducted according to international standard ISO 294-4; bending performance testing was conducted according to national standard GB / T 9341-2008; and tensile performance testing was conducted according to national standard GB / T 1040.2-2006. The test results are as follows:

[0046]

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A PVDF profile, characterized in that, The product includes polyvinylidene fluoride and a filler, wherein the method for preparing the filler includes the following steps: (1) Weigh 4-bromobenzocyclobutene and dissolve it in tetrahydrofuran solvent. Add magnesium powder and slowly add dimethylchlorosilane under stirring. After the addition is complete, continue stirring for 10-20 h. After the reaction is complete, centrifuge to separate the precipitate and remove the solvent under reduced pressure to obtain product A. (2) Under a protective atmosphere, triethoxyethylene silane was dissolved in tetrahydrofuran solvent, iodine and magnesium powder were added, and 2-adamantane-4-bromo-1-(2,2,2-trifluoroethoxy)benzene was slowly added under stirring. After the addition was completed, the reaction was stirred for 5-10 h. After the reaction was completed, cyclohexane was added to dilute the reaction system, the precipitate was separated by centrifugation, and the solvent was removed by vacuum distillation to obtain product B. Product A was dissolved in toluene solvent, and product B and perfluorotriphenylborone were added under stirring. The reaction was stirred for 2-5 h at room temperature. After the reaction was completed, the product was concentrated under vacuum, purified by chromatography to remove unreacted reactants, and the solvent was removed by vacuum distillation to obtain product C. (3) The nano-silica is surface-treated with a vinylsilane coupling agent to obtain a precursor product; the C product is dissolved in a mestriylbenzene solvent, the precursor product is added and stirred and dispersed, stirred and refluxed at 150-160℃ for 2-8h, cooled and the precipitate is separated, and after the solvent in the precipitate is evaporated, the temperature is raised to 210-250℃ under a protective atmosphere and kept at the temperature for 1-3h, and cooled to obtain the product; In step (1), the mass ratio of 4-bromobenzocyclobutene to the magnesium powder and the dimethylchlorosilane is 10:(1.8-2):(10-11). In step (2), the mass ratio of the triethoxyethylene silane to the iodine, the magnesium powder, and the 2-adamantane-4-bromo-1-(2,2,2-trifluoroethoxy)benzene is 10:(0.13-0.15):(1.34-1.52):(14-16). In step (2), the mass ratio of product A to product B and perfluorotriphenylborone is 10:(13-15):(0.07-0.09). The particle size of the nano-silica mentioned in step (3) is 100-1000 nm; The vinyl silane coupling agent mentioned in step (3) is vinyltrimethoxysilane, vinylmethoxydiethoxysilane, vinyltriethoxysilane, vinylethoxydiisopropoxysilane, vinyltriisopropoxysilane, γ-methacryloyloxypropyltrimethoxysilane, and γ-methacryloyloxypropyltriisopropoxysilane. The mass ratio of product C to the precursor product in step (3) is (1-2.4):

1.

2. The PVDF profile according to claim 1, characterized in that, The weight-average molecular weight of the polyvinylidene fluoride is between 100,000 and 1,000,000.

3. The PVDF profile according to claim 1, characterized in that, The mass ratio of polyvinylidene fluoride to the filler is (6-10):

1.

4. The manufacturing process of a PVDF profile according to any one of claims 1-3, characterized in that, Includes the following steps: S1. Prepare the packing material for later use; S2. The polyvinylidene fluoride is mixed with the filler and then extruded and granulated at 250-300°C to obtain the final product.

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