Preparation method of hydrophobic modified polypropylene plastic

Abstract

The invention discloses a preparation method of hydrophobic modified polypropylene plastic, and belongs to the technical field of polypropylene plastic. Comprising the following raw materials in parts by weight: 60-70 parts of polypropylene resin, 22-28 parts of polytetrafluoroethylene resin, 11-17 parts of modified nano titanium dioxide, 0.1-0.3 part of an initiator, 2-4 parts of a processing aid, 3-5 parts of an antioxidant and 5-15 parts of a modifier. Polytetrafluoroethylene is added into the prepared polypropylene plastic raw material, so that the hydrophobicity and flame retardance of the plastic are greatly enhanced; wherein the modified nano titanium dioxide can improve the processability, the mechanical property and the hydrophobicity of the plastic; wherein molecules of the modifier contain various functional groups, so that the hydrophobicity and flame retardance of the plastic are enhanced, the compatibility of polypropylene and polytetrafluoroethylene can also be enhanced, and the performance is long and stable; therefore, the prepared polypropylene plastic is high in hydrophobicity and stable and efficient in flame retardance, and has important application value in the technical field of polypropylene plastic.

Description

Technical Field

[0001] The invention belongs to the technical field of polypropylene plastics, and in particular relates to a method for preparing hydrophobically modified polypropylene plastics. Background Art

[0002] Polypropylene (PP) is a semi-crystalline thermoplastic plastic, usually a translucent colorless solid, odorless and non-toxic. Due to its regular structure and high degree of crystallization, its melting point is as high as 167°C. It is heat-resistant and can be used at around 100°C. Its outstanding advantage is that its products can be sterilized by steam. The density is 0.90g / cm 3 It is the lightest general-purpose plastic. It has good electrical properties and high-frequency insulation and is not affected by humidity. It is suitable for making general mechanical parts, corrosion-resistant parts and insulating parts. It does not require particularly harsh conditions for molding. It is widely used in the industry and is one of the most common polymer materials.

[0003] Polypropylene is mainly used in the following aspects: 1. Polypropylene fiber for engineering, 2. Biaxially oriented polypropylene film (BOPP), 3. Modified polypropylene for automobiles, 4. Polypropylene for household appliances, 5. Polypropylene for pipes, 6. Highly transparent polypropylene. In the field of household appliances, with the current product upgrades and the improvement of customer requirements, many household appliances and electrical appliances made of polypropylene materials, such as dishwasher liner, electrical box, washing machine and other parts that come into contact with water, will be covered with water droplets or residual water, which is easy to contaminate and breed bacteria, and in more serious cases, cause circuit short circuits and other hazards.

[0004] Inspired by the lotus effect, the preparation and research of super-hydrophobic polypropylene with a contact angle of more than 150° with water has aroused widespread interest in the industry. Since the contact area of ​​liquid on super-hydrophobic materials is very small, it can effectively inhibit surface oxidation, corrosion, frost, current conduction and other phenomena, and give the material excellent self-cleaning and waterproof properties, greatly expanding the scope of use of polypropylene materials. At present, the method for preparing super-hydrophobic polypropylene is relatively complicated, and polypropylene, as a polymer material, has a poor oxygen index. Therefore, it is urgent to solve the above problems to meet the higher demands in the field of polypropylene plastic technology. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the prior art and provide a method for preparing hydrophobically modified polypropylene plastic.

[0006] The purpose of the present invention can be achieved through the following technical solutions: A method for preparing a hydrophobically modified polypropylene plastic comprises the following steps: The polypropylene resin and polytetrafluoroethylene resin are dried in an oven for 12 hours, taken out after drying, added into a mixer together with modified nano titanium dioxide, an initiator, a processing aid, an antioxidant and a modifier, mixed and stirred evenly, and then added into a twin-screw extruder, melt blended, and extruded to obtain a hydrophobically modified polypropylene plastic.

[0007] Furthermore, the raw materials are calculated in parts by weight as follows: 60-70 parts of polypropylene resin, 22-28 parts of polytetrafluoroethylene resin, 11-17 parts of modified nano titanium dioxide, 0.1-0.3 parts of initiator, 2-4 parts of processing aid, 3-5 parts of antioxidant, and 5-15 parts of modifier.

[0008] Furthermore, the initiator is one of benzoyl peroxide and lauroyl peroxide.

[0009] Furthermore, the antioxidant is a hindered phenol antioxidant.

[0010] Furthermore, the processing aid is one of calcium stearate, zinc stearate and paraffin.

[0011] Polytetrafluoroethylene is added to the raw materials. Polytetrafluoroethylene molecules contain a large number of carbon-fluorine bonds, which can greatly enhance the hydrophobicity and flame retardant properties of the plastic.

[0012] Furthermore, the modified nano titanium dioxide is prepared by the following steps: Place the nano-titanium dioxide in a vacuum drying oven, dry it at 60°C for 12 hours, cool it and set it aside, then add anhydrous ethanol and deionized water into a three-necked flask, stir it evenly with a glass rod, then add the dried nano-titanium dioxide into the three-necked flask, stir and mix evenly, drop ammonia water into the solution, adjust the pH of the solution to 9, ultrasonically treat it for 30 minutes, then add silane coupling agent KH-570 into the three-necked flask, place the device in an oil bath at 80°C, reflux for 4 hours, centrifuge the reactant with a centrifuge, wash it with n-heptane 4-5 times, finally dry the product in a vacuum oven at 60°C, and grind it to obtain modified nano-titanium dioxide.

[0013] Furthermore, the usage ratio of nano titanium dioxide, anhydrous ethanol, deionized water, and silane coupling agent KH-570 is 1 g:50 mL:50 mL:5.5 g.

[0014] Silane coupling agent KH-570 can condense with the hydroxyl groups on the surface of nano-titanium dioxide to form Ti-O-Si bonds encapsulating TiO 2The surface can improve the surface hydrophobicity of nano titanium dioxide. After hydrophobization, the inorganic nanoparticles can reduce the surface energy of the matrix to a certain extent, form a micro-nano binary rough structure with the matrix, and improve the hydrophobicity of the matrix; and the modified nano titanium dioxide can also be used as a filling material to improve the creep resistance of polytetrafluoroethylene, thereby enhancing the processability and mechanical properties of the plastic.

[0015] Furthermore, the modifier is prepared by the following steps: S1. In a three-necked flask equipped with a stirring device, p-aminobenzaldehyde, 7H-dodecafluoroheptanoic acid, DCC (dicyclohexylcarbodiimide, a dehydrating agent) and toluene were mixed and stirred evenly, placed in a 55°C water bath, and stirred for 4 hours. After the reaction, part of the solvent was first removed by rotary evaporation, and then purified by column chromatography (the eluent was a mixed solvent of ethyl acetate / petroleum ether, and the volume ratio of the two was 1:4). The eluent was removed by rotary evaporation to obtain intermediate 1; the ratio of p-aminobenzaldehyde, 7H-dodecafluoroheptanoic acid, dicyclohexylcarbodiimide and toluene was 12.1g:34.5g:20.6g:150mL; Under the action of a dehydrating agent, the amino group on p-aminobenzaldehyde and the carboxyl group on 7H-dodecafluoroheptanoic acid undergo an amidation reaction to obtain intermediate 1. The specific reaction process is as follows: ; S2. Add intermediate 1, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and toluene into a three-necked flask equipped with a reflux condenser and mechanical stirring, and continue to introduce N 2 The device was heated to 80°C and stirred for 30 min. After all the solids were dissolved, the temperature was raised to 135°C and stirred for 6 h. After the reaction was completed, the filter was filtered under reduced pressure. The residue was washed 3-4 times with a mixed solvent of ethyl acetate and petroleum ether (the volume ratio of the two was 1:4), and vacuum dried to obtain intermediate 2. The ratio of the amount of intermediate 1, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and toluene was 44.9 g:21.6 g:150 mL. The active PH bond in the structure of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide can react with the C=O bond of the aldehyde group in the intermediate 1 molecule to obtain intermediate 2; the specific reaction process is as follows: ; S3. In a three-necked flask equipped with a stirring device, nitrogen is introduced to discharge the air in the device, and then the intermediate 2, 4-pentenoic acid chloride and toluene are added. After stirring and mixing, 4-dimethylaminopyridine (DMAP, catalyst) and triethylamine (acid binding agent) are added. After stirring and mixing again, the reaction temperature is controlled to 80°C, and the reaction is kept warm for 6 hours. Stirring is continued during the reaction. After the reaction is completed, the mixture is filtered, and part of the solvent is removed by rotary evaporation. Then, the mixture is purified by column chromatography (the eluent is a mixed solvent of ethyl acetate / petroleum ether, and the volume ratio of the two is 1:5), and the eluent is removed by rotary evaporation to obtain a modifier; the ratio of the intermediate 2, 4-pentenoic acid chloride, toluene, 4-dimethylaminopyridine, and triethylamine is 66.5g:11.8g:100mL:0.2g:15mL; Under the catalysis of 4-dimethylaminopyridine and triethylamine, the acyl chloride on 4-pentenoic acid chloride and the hydroxyl group on intermediate 2 undergo acylation reaction to obtain a modifier; the specific reaction process is as follows: ; The prepared modifier molecules contain a large number of fluorine-carbon bonds and are fluorine-containing compounds. From the perspective of molecular structure and atomic arrangement, among materials with carbon as the skeleton, the fluorine-carbon bond energy is the highest (460.2 kJ / mol), the polarizability is the lowest, and the electronegativity of fluorine atoms is the largest, which increases the repulsion between the carbon atoms connected to it, so that the carbon-carbon main axis is arranged in a spiral and is completely wrapped by fluorine atoms, thereby greatly reducing the surface energy of the polypropylene matrix and greatly improving the hydrophobicity of polypropylene; in addition, the modifier molecule also contains a benzene ring, DOPD and a carbon-carbon double bond structure, among which the benzene ring is a hydrophobic group, which can further improve the hydrophobicity of the matrix; the introduced DOPO is an environmentally friendly flame retardant with the advantages of high efficiency and low toxicity, and has good thermal stability and strong flame retardant durability, which can enhance the flame retardant properties of the matrix; finally, the carbon-carbon double bond at one end of the modifier molecule can, under the action of the initiator, chemically bond with the polypropylene matrix, so that the modifier molecule is grafted on the macromolecular chain of polypropylene, which not only improves the stability of the modifier, but also improves the compatibility of polypropylene with polytetrafluoroethylene.

[0016] Beneficial effects of the present invention: 1. Polytetrafluoroethylene is added to the polypropylene plastic raw material prepared by the present invention, which greatly enhances the hydrophobicity and flame retardant properties of the plastic; 2. By hydrophobic modification of nano-titanium dioxide, the processability, mechanical properties and hydrophobicity of plastics are improved; 3. The prepared modifier molecules contain various functional groups, which greatly enhance the hydrophobicity and flame retardancy of plastics, and can also enhance the compatibility of polypropylene and polytetrafluoroethylene, and the performance is long-term and stable; Therefore, the polypropylene plastic prepared by the present invention has strong hydrophobicity and stable and efficient flame retardancy, and has important application value in the technical field of polypropylene plastics. DETAILED DESCRIPTION

[0017] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] Embodiment 1

[0019] Preparation of modifier: S1. In a three-necked flask equipped with a stirring device, 12.1 g of p-aminobenzaldehyde, 34.5 g of 7H-dodecafluoroheptanoic acid, 20.6 g of DCC and 150 mL of toluene were mixed and stirred evenly, and placed in a 55°C water bath, stirred and reacted for 4 hours. After the reaction was completed, part of the solvent was first removed by rotary evaporation, and then purified by column chromatography (the eluent was a mixed solvent of ethyl acetate / petroleum ether, and the volume ratio of the two was 1:4), and the eluent was removed by rotary evaporation to obtain intermediate 1; S2. In a three-necked flask equipped with a reflux condenser and mechanical stirring, 44.9 g of intermediate 1, 21.6 g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 150 mL of toluene were added, and N 2 After the solid was completely dissolved, the temperature was raised to 135°C and stirred for 6 hours. After the reaction was completed, the residue was filtered off under reduced pressure and washed three times with a mixed solvent of ethyl acetate and petroleum ether (the volume ratio of the two was 1:4), and dried under vacuum to obtain intermediate 2. S3. In a three-necked flask equipped with a stirring device, nitrogen was introduced into the air in the exhaust device, and then 66.5 g of intermediate 2, 11.8 g of 4-pentenoic acid chloride and 100 mL of toluene were added. After stirring and mixing evenly, 0.2 g of 4-dimethylaminopyridine and 15 mL of triethylamine were added. After stirring and mixing again, the reaction temperature was controlled to 80°C, and the reaction was kept warm for 6 hours. Stirring was continued during the reaction. After the reaction was completed, the reaction was filtered, and part of the solvent was removed by rotary evaporation. Then, it was purified by column chromatography (the eluent was a mixed solvent of ethyl acetate / petroleum ether, and the volume ratio of the two was 1:5), and the eluent was removed by rotary evaporation to obtain a modifier.

[0020] Embodiment 2

[0021] Preparation of modifier: S1. In a three-necked flask equipped with a stirring device, 24.2 g of p-aminobenzaldehyde, 69 g of 7H-dodecafluoroheptanoic acid, 41.2 g of DCC and 300 mL of toluene were mixed and stirred evenly, placed in a 55°C water bath, and stirred for reaction for 4 hours. After the reaction was completed, part of the solvent was first removed by rotary evaporation, and then purified by column chromatography (the eluent was a mixed solvent of ethyl acetate / petroleum ether, and the volume ratio of the two was 1:4), and the eluent was removed by rotary evaporation to obtain intermediate 1; S2. In a three-necked flask equipped with a reflux condenser and mechanical stirring, 89.8 g of intermediate 1, 43.2 g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 300 mL of toluene were added, and N 2 After the solid was completely dissolved, the temperature was raised to 135°C and stirred for 6 hours. After the reaction was completed, the residue was filtered off under reduced pressure and washed three times with a mixed solvent of ethyl acetate and petroleum ether (the volume ratio of the two was 1:4), and dried under vacuum to obtain intermediate 2. S3. In a three-necked flask equipped with a stirring device, nitrogen was introduced into the air in the exhaust device, and then 133 g of intermediate 2, 23.6 g of 4-pentenoic acid chloride and 200 mL of toluene were added. After stirring and mixing evenly, 0.4 g of 4-dimethylaminopyridine and 30 mL of triethylamine were added. After stirring and mixing again, the reaction temperature was controlled to 80°C, and the reaction was kept warm for 6 hours. Stirring was continued during the reaction. After the reaction was completed, the reaction was filtered, and part of the solvent was removed by rotary evaporation. Then, it was purified by column chromatography (the eluent was a mixed solvent of ethyl acetate / petroleum ether, and the volume ratio of the two was 1:5), and the eluent was removed by rotary evaporation to obtain a modifier.

[0022] Embodiment 3

[0023] Preparation of modified nano-titanium dioxide: Place 1g of nano-titanium dioxide in a vacuum drying oven, dry it at 60°C for 12h, cool it and set it aside, then add 50mL of anhydrous ethanol and 50mL of deionized water into a three-necked flask, stir it evenly with a glass rod, then add the dried nano-titanium dioxide into the three-necked flask, stir and mix evenly, add ammonia water dropwise into the solution, adjust the pH of the solution to 9, ultrasonically treat it for 30min, then add 5.5g of silane coupling agent KH-570 into the three-necked flask, place the device in an oil bath at 80°C, reflux for 4h, centrifuge the reactant with a centrifuge, wash it with n-heptane 4 times, finally dry the product in a vacuum oven at 60°C, and grind it to obtain modified nano-titanium dioxide.

[0024] Embodiment 4

[0025] 60g of polypropylene resin and 22g of polytetrafluoroethylene resin were dried in an oven for 12h, taken out after drying, added into a blender with 11g of modified nano titanium dioxide prepared in Example 3, 0.1g of benzoyl peroxide, 2g of calcium stearate, 3g of antioxidant 1010 and 5g of the modifier prepared in Example 1, mixed and stirred evenly, and then added into a twin-screw extruder, melt blended, and extruded to obtain a hydrophobically modified polypropylene plastic.

[0026] Embodiment 5

[0027] 65g of polypropylene resin and 25g of polytetrafluoroethylene resin were dried in an oven for 12h, taken out after drying, added into a blender with 14g of modified nano titanium dioxide prepared in Example 3, 0.2g of lauroyl peroxide, 3g of zinc stearate, 4g of antioxidant 1010 and 10g of the modifier prepared in Example 2, mixed and stirred evenly, and then added into a twin-screw extruder, melt blended, and extruded to obtain a hydrophobically modified polypropylene plastic.

[0028] Embodiment 6

[0029] 70g of polypropylene resin and 28g of polytetrafluoroethylene resin were dried in an oven for 12h, taken out after drying, added into a blender with 17g of modified nano titanium dioxide prepared in Example 3, 0.3g of lauroyl peroxide, 4g of paraffin, 5g of antioxidant 1010 and 15g of the modifier prepared in Example 2, mixed and stirred evenly, and then added into a twin-screw extruder, melt blended, and extruded to obtain a hydrophobically modified polypropylene plastic.

[0030] Comparative Example 1 The modifier in Example 6 was replaced by a commercially available flame retardant of equal quality, and the remaining steps were the same as those in Example 6.

[0031] Comparative Example 2 Commercially available superhydrophobic polypropylene was used.

[0032] Embodiments 4, 5, 6 and comparative examples 1 and 2 were made into corresponding shapes according to different test standards and the following performance tests were performed: The national standard GB / T 30693-2014 was used to measure the water contact angle of the surface; The limiting oxygen index was determined using the national standard GB / T 2406-2008, and then Examples 4, 5, 6 and Comparative Example 1 were left to stand at room temperature for 200 days, and the oxygen index was then determined using the same standard; The measured results are shown in the following table: ; It can be seen from the above table that the polypropylene plastic prepared in the embodiment of the present invention has excellent hydrophobicity and flame retardancy, and still maintains excellent flame retardancy after 200 days. Therefore, the present invention has important application value in the field of polypropylene plastic technology.

[0033] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0034] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A method for preparing a hydrophobically modified polypropylene plastic, characterized in that: The following steps are involved: The polypropylene resin and the polytetrafluoroethylene resin are dried in an oven for 12 hours, taken out after drying, added into a mixer together with modified nano titanium dioxide, an initiator, a processing aid, an antioxidant and a modifier, mixed and stirred evenly, and then added into a twin-screw extruder, melt blended, and extruded to obtain a hydrophobically modified polypropylene plastic; Wherein, the modifier is prepared by the following steps: S1, p-aminobenzaldehyde, 7H-dodecafluoroheptanoic acid, dicyclohexylcarbodiimide and toluene were mixed and stirred evenly, placed in a 55°C water bath, stirred and reacted for 4 hours, and after the reaction was completed, rotary evaporation, column chromatography purification, and rotary evaporation to obtain intermediate 1; S2. Add intermediate 1, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and toluene into a three-necked flask, and continue to introduce N2 for protection. Then heat the device to 80°C and stir for 30 min. After all the solids are dissolved, raise the temperature to 135°C and stir for 6 h. After the reaction is complete, filter under reduced pressure, wash the filter residue, and dry in vacuo to obtain intermediate 2. S3. In a three-necked flask, introduce nitrogen, add the intermediate 2, 4-pentenoic acid chloride and toluene, stir and mix evenly, then add 4-dimethylaminopyridine and triethylamine, stir and mix again, and keep the reaction at 80°C for 6 hours. Stir continuously during the reaction. After the reaction is completed, filter, rotary evaporate, purify by column chromatography, and rotary evaporate to obtain the modifier.

2. The method for preparing a hydrophobically modified polypropylene plastic according to claim 1, characterized in that: In step S1, the ratio of p-aminobenzaldehyde, 7H-dodecafluoroheptanoic acid, dicyclohexylcarbodiimide and toluene is 12.1 g:34.5 g:20.6 g:150 mL.

3. The method for preparing a hydrophobically modified polypropylene plastic according to claim 1, characterized in that: In step S2, the ratio of the amount of intermediate 1, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and toluene is 44.9 g:21.6 g:150 mL.

4. The method for preparing a hydrophobically modified polypropylene plastic according to claim 1, characterized in that: In step S3, the ratio of the amount of intermediate 2, 4-pentenoic acid chloride, toluene, 4-dimethylaminopyridine and triethylamine is 66.5 g:11.8 g:100 mL:0.2 g:15 mL.

5. The method for preparing a hydrophobically modified polypropylene plastic according to claim 1, characterized in that: The raw materials are calculated in parts by weight as follows: 60-70 parts of polypropylene resin, 22-28 parts of polytetrafluoroethylene resin, 11-17 parts of modified nano titanium dioxide, 0.1-0.3 parts of initiator, 2-4 parts of processing aid, 3-5 parts of antioxidant, and 5-15 parts of modifier.

6. The method for preparing a hydrophobically modified polypropylene plastic according to claim 1, characterized in that: The modified nano titanium dioxide is prepared by the following steps: The nano-titanium dioxide was dried and cooled for use, and then anhydrous ethanol and deionized water were added to a three-necked flask and stirred evenly. The dried nano-titanium dioxide was then added to the three-necked flask and stirred evenly. The pH of the solution was adjusted to 9. After ultrasonic treatment for 30 minutes, silane coupling agent KH-570 was added to the three-necked flask. The device was placed in an oil bath at 80°C, refluxed for 4 hours, centrifuged, washed, dried, and ground to obtain modified nano-titanium dioxide.

7. The method for preparing a hydrophobically modified polypropylene plastic according to claim 1, characterized in that: The initiator is one of benzoyl peroxide and lauroyl peroxide.

8. The method for preparing a hydrophobically modified polypropylene plastic according to claim 1, characterized in that: The antioxidant is a hindered phenol antioxidant.

9. The method for preparing a hydrophobically modified polypropylene plastic according to claim 1, characterized in that: The processing aid is one of calcium stearate, zinc stearate and paraffin.