CN111574801A - High-toughness polypropylene plastic and preparation method thereof - Google Patents

Abstract

The invention discloses a high-toughness polypropylene plastic which is prepared from the following raw materials in parts by weight: 70-80 parts of modified polypropylene, 15-20 parts of reinforcing filler and 0.8-1 part of antioxidant; the polypropylene plastic is prepared by the following method: adding modified polypropylene on an open type heat mill with the double-roller temperature of 170-180 ℃, sequentially adding an antioxidant and a reinforcing filler after the modified polypropylene is melted and coated on a roller, uniformly mixing, and extruding and granulating by a double-screw extruder. According to the invention, the modified polypropylene is adopted as the plastic matrix, and the modified polypropylene is modified by grafting, so that the toughness of the polypropylene can be improved by forming a network structure, the crystallization of the polypropylene can be accelerated, and the quality of the polypropylene can be improved; the addition of the reinforcing filler has excellent compatibility with a PP matrix, and can interact with a modified PP molecular chain to reinforce the acting force of the filler and the matrix, so that the inorganic filler is uniformly and stably dispersed in the matrix, and the reinforcing and toughening effects are exerted.

Description

High-toughness polypropylene plastic and preparation method thereof

Technical Field

The invention belongs to the field of polypropylene plastics, and particularly relates to a high-toughness polypropylene plastic and a preparation method thereof.

Background

The polypropylene is a non-toxic, odorless and tasteless milky-white high-crystallization polymer, is one of the lightest varieties of all plastics at present, has good heat resistance, and can reach the continuous use temperature of 110-120 ℃; good chemical performance, almost no water absorption, no reaction with most chemicals, pure texture and no toxicity. The method is widely applied to the production of fiber products such as clothes, blankets and the like, medical instruments, automobiles, bicycles, parts, conveying pipelines, chemical containers and the like, and is also used for packaging foods and medicines. However, when the engineering component is made of polypropylene material, the toughness of the polypropylene material is difficult to meet the use requirement, which limits the application of polypropylene in the engineering component.

Chinese patent No. CN201711218467.3 discloses a preparation method of polypropylene plastic for a high-toughness instrument board, which comprises the following steps: random copolymerization polypropylene, nitrile silicone rubber, methyl methacrylate-butadiene-styrene terpolymer, 1-bis- (tert-butylperoxy) cyclohexane, calcium oxide compound, lignin fiber, nano bentonite, heavy calcium carbonate, coal gangue powder, mica powder, an anti-aging agent ODA, an anti-aging agent, pine tar, BLE polyethylene oxide and coumarone resin are stirred, and then the mixture is put into a double-screw extruder to be extruded and granulated to obtain the high-toughness polypropylene plastic for instrument panels. The application toughens by adding the rubber elastomer, and the effect is remarkable, but at the expense of precious properties such as rigidity, strength, heat resistance, dimensional stability and processability of the plastic.

Disclosure of Invention

The invention aims to provide a high-toughness polypropylene plastic and a preparation method thereof, wherein modified polypropylene is adopted as a plastic matrix, and the modified polypropylene is modified by grafting, so that the toughness of the polypropylene can be improved by forming a network structure, the crystallization of the polypropylene can be accelerated, and the quality of the polypropylene can be improved; the addition of the reinforcing filler has excellent compatibility with a PP matrix, and can interact with a modified PP molecular chain to reinforce the acting force of the filler and the matrix, so that the inorganic filler is uniformly and stably dispersed in the matrix to exert the reinforcing and toughening effects; the obtained polypropylene resin has high toughness and strong mechanical property, and has wide application range.

The purpose of the invention can be realized by the following technical scheme:

the high-toughness polypropylene plastic is prepared from the following raw materials in parts by weight: 70-80 parts of modified polypropylene, 15-20 parts of reinforcing filler and 0.8-1 part of antioxidant;

the polypropylene plastic is prepared by the following method:

the modified polypropylene is firstly added into an open type heat mill with the double-roller temperature of 170-180 ℃, the antioxidant and the reinforcing filler are sequentially added after the modified polypropylene is melted and coated on the rollers, and the mixture is uniformly mixed and then extruded and granulated by a double-screw extruder to prepare the high-toughness polypropylene plastic.

Further, the modified polypropylene is prepared by the following method:

s1, sequentially adding pentaerythritol, 4-hydroxycrotonic acid and toluene into a four-necked bottle provided with a stirrer, a thermometer, a water separator and an air guide pipe, stirring for 5min, adding a polymerization inhibitor, a catalyst and a decolorizing agent, heating and maintaining the temperature at 80-90 ℃ for reflux reaction, testing the residual acid value of a reaction solution to a target range, finishing the reaction, cooling to room temperature, sequentially washing and extracting with a NaCl solution and a sodium carbonate solution, collecting an oil layer, neutralizing the pH value to 7.0 with a sodium hydroxide solution, washing with a 5% sodium chloride solution, collecting the oil layer, adding anhydrous sodium sulfate, drying overnight, filtering, and distilling at 40-50 ℃ under reduced pressure to remove the solvent to obtain a modifier;

s2, performing surface treatment on the polypropylene surface by using air plasma, wherein the treatment voltage is 70V, the treatment time is 4-5min, and the gas flow rate is 100 mL/min; the treated polypropylene was mixed with the modifier prepared above according to a ratio of 25: 1, putting the mixture into a torque rheometer for melt grafting at the rotating speed of 60r/min and the blending temperature of 180 ℃ for 15-18 min;

s3, completely dissolving the molten mixture in xylene at 140 ℃, precipitating with acetone, filtering, repeating the operation for 3-4 times, and drying the product in a vacuum drying oven at 80 ℃ for 2d to obtain the modified polypropylene.

Further, in step S1, the ratio of the amounts of pentaerythritol, 4-hydroxycrotonic acid, and toluene is 1: 4.2: 2; the dosage of the catalyst is 4 percent of the mass of the pentaerythritol, the dosage of the polymerization inhibitor is 3.5 percent of the mass of the acrylic acid, the dosage of the decolorizing agent is 3 percent of the dosage of the pentaerythritol, and the target acid value is less than 1.

Further, the reinforcing filler is prepared by the following method:

(1) mixing graphene oxide and nano silicon dioxide according to a mass ratio of 10: 6-7, mixing according to a solid-liquid ratio of 1 g: dispersing 30mL of the aqueous solution in 3% by volume of acetic acid to form a dispersion liquid;

(2) according to the solid-liquid ratio of 1 g: adding 10mL of sebacic acid into methanol, stirring for 10-15min, and mixing with the dispersion according to a volume ratio of 1: 1, mixing, and mechanically stirring at 35-40 ℃ for reaction for 22-24 h;

(3) after the reaction is finished, washing the mixture by using 0.1mol/L NaOH solution, distilled water, 0.1mol/L HCl solution, distilled water and ethanol in sequence, and drying the mixture in a vacuum drying oven at the temperature of 30 ℃ for 24 hours to obtain the reinforced filler.

A preparation method of high-toughness polypropylene plastic comprises the following steps:

the modified polypropylene is firstly added into an open type heat mill with the double-roller temperature of 170-180 ℃, the antioxidant and the reinforcing filler are sequentially added after the modified polypropylene is melted and coated on the rollers, and the mixture is uniformly mixed and then extruded and granulated by a double-screw extruder to prepare the high-toughness polypropylene plastic.

The invention has the beneficial effects that:

the modified polypropylene is adopted as a plastic matrix, and the polypropylene surface can generate free radical reaction with a modifier (mainly double bonds on modifier molecules) after plasma treatment, so that the modifier is grafted on the polypropylene molecules to obtain the modified polypropylene; on one hand, the modifier is a compound containing a plurality of branched chains, each branched chain contains C, so that one modifier molecule can react with a plurality of polypropylene molecular chains, the function of bridge crosslinking is achieved among the plurality of PP molecular chains, the polypropylene molecular chains form a plurality of winding sites to form a network structure, compared with the original PP, the network structure is easy to deform under the action of external force, and the macroscopic expression is the toughness enhancement, so that the toughening effect is achieved on the PP; on the other hand, the modifier molecules have the nucleation promoting effect, so that the nucleation density of the crystal can be improved, the crystallization of PP is accelerated, and the quality of the modified polypropylene is improved;

according to the invention, the reinforcing filler is added into the plastic raw material, the-COOH on the sebacic acid can react with-OH functional groups on the surfaces of the graphene oxide and the nano silicon dioxide, so that the sebacic acid is grafted on the surface of the filler, and the long carbon chain wraps the structure of the filler particles because the sebacic acid contains the long carbon chain; when the reinforced filler is blended with the modified polypropylene matrix, on one hand, the surface of the filler is coated with long carbon chains, and the long carbon chains have good compatibility with the PP matrix and can promote the dispersion of the reinforced filler in the PP matrix; on the other hand, sebacic acid is dibasic acid, when the dibasic acid is grafted on the surface of the filler, unreacted-COOH can be introduced, so that the surface of the filler particle contains-COOH functional groups, a modifier is introduced on a modified PP molecular chain, a branched chain of a modifier molecule contains-OH, and the-COOH on the surface of the filler can react with the-OH on the modifier molecule in the melting and mixing process, so that the acting force of the filler particle and a matrix can be effectively improved, the dispersion of the filler is further promoted, and the filler can uniformly and stably exert a reinforcing effect in a polymer system; the addition of the inorganic rigid particles (graphene oxide and nano silicon dioxide) can form a stress concentration effect, and form silver lines and shear bands around the PP matrix, and the silver lines and the shear bands can absorb external force so as to increase the impact toughness of the PP;

according to the invention, the modified polypropylene is adopted as the plastic matrix, and the modified polypropylene is modified by grafting, so that the toughness of the polypropylene can be improved by forming a network structure, the crystallization of the polypropylene can be accelerated, and the quality of the polypropylene can be improved; the addition of the reinforcing filler has excellent compatibility with a PP matrix, and can interact with a modified PP molecular chain to reinforce the acting force of the filler and the matrix, so that the inorganic filler is uniformly and stably dispersed in the matrix to exert the reinforcing and toughening effects; the obtained polypropylene resin has high toughness and strong mechanical property, and has wide application range.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The high-toughness polypropylene plastic is prepared from the following raw materials in parts by weight: 70-80 parts of modified polypropylene, 15-20 parts of reinforcing filler and 0.8-1 part of antioxidant;

wherein the antioxidant is common antioxidant for polypropylene resin, such as antioxidant JC-1215 and antioxidant JC-1225;

the modified polypropylene is prepared by the following method:

s1, sequentially adding pentaerythritol, 4-hydroxycrotonic acid and toluene into a four-necked bottle provided with a stirrer, a thermometer, a water separator and an air guide pipe, stirring for 5min, adding a polymerization inhibitor, a catalyst and a decolorizing agent, heating and maintaining the temperature at 80-90 ℃ for reflux reaction, testing the residual acid value of the reaction solution, leading the acid value to reach a target value, finishing the reaction, cooling to room temperature, sequentially washing and extracting with a NaCl solution (the mass fraction is 5%) and a sodium carbonate solution (the mass fraction is 15%), collecting an oil layer, neutralizing the pH value to 7.0 with a sodium hydroxide solution (the mass fraction is 5%), washing with a 5% sodium chloride solution, collecting the oil layer, adding anhydrous sodium sulfate, drying overnight, filtering, and distilling at 40-50 ℃ under reduced pressure to remove the solvent to obtain a modifier;

wherein, the mass ratio of pentaerythritol, 4-hydroxycrotonic acid and toluene is 1: 4.2: 2; the dosage of the catalyst (p-toluenesulfonic acid) is 4 percent of the mass of pentaerythritol, the dosage of the polymerization inhibitor is 3.5 percent of the mass of acrylic acid, the dosage of the decolorizing agent is 3 percent of the dosage of pentaerythritol, and the target acid value is less than 1;

reacting-OH on pentaerythritol with-COOH on 4-hydroxycrotonic acid by an ester hydrolysis method, wherein each hydroxyl is grafted with a 4-hydroxycrotonic acid molecule through an esterification reaction due to four hydroxyl groups on the pentaerythritol to generate a modifier with a multi-branched structure;due to 4-hydroxycrotonic acid (HOOC-CH ═ CH-CH)₂-OH) contains a C ═ C carbon-carbon double bond and-OH, and therefore, the modifier contains C ═ C and hydroxyl groups on a plurality of branches; it should be noted here that 4-hydroxycrotonic acid has a short molecular chain, and intramolecular esterification needs to overcome a great amount of steric hindrance, so that during the esterification reaction with pentaerythritol, — COOH thereon preferentially undergoes an esterification reaction with — OH on the pentaerythritol molecule to form the target modifier compound;

s2, performing surface treatment on the polypropylene surface by using air plasma, wherein the treatment voltage is 70V, the treatment time is 4-5min, and the gas flow rate is 100 mL/min; the treated polypropylene was mixed with the modifier prepared above according to a ratio of 25: 1, putting the mixture into a torque rheometer for melt grafting at the rotating speed of 60r/min and the blending temperature of 180 ℃ for 15-18 min;

s3, completely dissolving the molten mixture in xylene at 140 ℃, precipitating with acetone, filtering, repeating the operation for 3-4 times, and drying the product in a vacuum drying oven at 80 ℃ for 2d to obtain modified polypropylene;

after the surface of the polypropylene is treated by plasma, the polypropylene can generate free radical reaction with a modifier (mainly double bonds on modifier molecules), so that the modifier is grafted on the polypropylene molecules to obtain modified polypropylene; on one hand, the modifier is a compound containing a plurality of branched chains, each branched chain contains C, so that one modifier molecule can react with a plurality of polypropylene molecular chains, the function of bridge crosslinking is achieved among the plurality of PP molecular chains, the polypropylene molecular chains form a plurality of winding sites to form a network structure, compared with the original PP, the network structure is easy to deform under the action of external force, and the macroscopic expression is the toughness enhancement, so that the toughening effect is achieved on the PP; on the other hand, the modifier molecules have the nucleation promoting effect, so that the nucleation density of the crystal can be improved, the crystallization of PP is accelerated, and the quality of the modified polypropylene is improved;

the reinforcing filler is prepared by the following method:

(1) mixing graphene oxide and nano silicon dioxide according to a mass ratio of 10: 6-7, mixing according to a solid-liquid ratio of 1 g: dispersing 30mL of the aqueous solution in 3% by volume of acetic acid to form a dispersion liquid;

(2) according to the solid-liquid ratio of 1 g: adding 10mL of sebacic acid into methanol, stirring for 10-15min, and mixing with the dispersion according to a volume ratio of 1: 1, mixing, and mechanically stirring at 35-40 ℃ for reaction for 22-24 h;

(3) after the reaction is finished, sequentially washing the mixture by using 0.1mol/L NaOH solution, distilled water, 0.1mol/L HCl solution, distilled water and ethanol, and drying the mixture in a vacuum drying oven at the temperature of 30 ℃ for 24 hours to obtain the reinforced filler;

the-COOH on the sebacic acid can react with-OH functional groups on the surfaces of the graphene oxide and the nano silicon dioxide to graft the sebacic acid on the surface of the filler, and the long carbon chain wraps the structure of the filler particles because the sebacic acid contains the long carbon chain; when the reinforced filler is blended with the modified polypropylene matrix, on one hand, the surface of the filler is coated with long carbon chains, and the long carbon chains have good compatibility with the PP matrix and can promote the dispersion of the reinforced filler in the PP matrix; on the other hand, sebacic acid is dibasic acid, when the dibasic acid is grafted on the surface of the filler, unreacted-COOH can be introduced, so that the surface of the filler particle contains-COOH functional groups, a modifier is introduced on a modified PP molecular chain, a branched chain of a modifier molecule contains-OH, and the-COOH on the surface of the filler can react with the-OH on the modifier molecule in the melting and mixing process, so that the acting force of the filler particle and a matrix can be effectively improved, the dispersion of the filler is further promoted, and the filler can uniformly and stably exert a reinforcing effect in a polymer system; the addition of the inorganic rigid particles (graphene oxide and nano silicon dioxide) can form a stress concentration effect, and form silver lines and shear bands around the PP matrix, and the silver lines and the shear bands can absorb external force so as to increase the impact toughness of the PP;

the preparation method of the polypropylene plastic comprises the following steps:

the modified polypropylene is firstly added into an open type heat mill with the double-roller temperature of 170-180 ℃, the antioxidant and the reinforcing filler are sequentially added after the modified polypropylene is melted and coated on the rollers, and the mixture is uniformly mixed and then extruded and granulated by a double-screw extruder to prepare the high-toughness polypropylene plastic.

Example 1

The high-toughness polypropylene plastic is prepared from the following raw materials in parts by weight: 70 parts of modified polypropylene, 15 parts of reinforcing filler and 0.8 part of antioxidant;

the polypropylene plastic is prepared by the following method:

adding modified polypropylene on an open type heat refining machine with the temperature of 170 ℃ between two rollers, sequentially adding an antioxidant and a reinforcing filler after the modified polypropylene is melted and coated on the rollers, uniformly mixing, and then extruding and granulating by a double-screw extruder to obtain the high-toughness polypropylene plastic.

Example 2

The high-toughness polypropylene plastic is prepared from the following raw materials in parts by weight: 75 parts of modified polypropylene, 18 parts of reinforcing filler and 0.9 part of antioxidant;

the polypropylene plastic is prepared by the following method:

adding modified polypropylene on an open type heat refining machine with the temperature of 175 ℃ between two rollers, sequentially adding an antioxidant and a reinforcing filler after the modified polypropylene is melted and wrapped by the rollers, uniformly mixing, and then extruding and granulating by a double-screw extruder to obtain the high-toughness polypropylene plastic.

Example 3

The high-toughness polypropylene plastic is prepared from the following raw materials in parts by weight: 80 parts of modified polypropylene, 20 parts of reinforcing filler and 1 part of antioxidant;

the polypropylene plastic is prepared by the following method:

adding modified polypropylene on an open type heat refining machine with the double-roll temperature of 180 ℃, sequentially adding an antioxidant and a reinforcing filler after the modified polypropylene is melted and coated on a roll, uniformly mixing, and then extruding and granulating by a double-screw extruder to obtain the high-toughness polypropylene plastic.

Comparative example 1

The modified polypropylene in example 1 was replaced with ordinary polypropylene, and the remaining raw materials and preparation process were unchanged.

Comparative example 2

The reinforcing filler in the example 1 is replaced by the graphene oxide and the nano silicon dioxide which are not subjected to any treatment, and the rest of raw materials and the preparation process are unchanged.

Comparative example 3

A polypropylene resin.

For the polypropylene plastics obtained in examples 1 to 3 and comparative examples 1 to 3, the following property tests were carried out by injection molding the plastic pellets into test specimens in accordance with GB/T17037.1-1997 at an injection temperature of 200 ℃:

testing the tensile property of the sample according to GB/T1040.2-2006, wherein the tensile speed is 50 mm/min; testing the bending property of the sample according to GB/T9341-2008; testing the impact resistance of the sample according to GB/T1843-2008; the MFR (melt flow rate) of the test specimens was measured in accordance with GB/T3682-2000, at a temperature of 230 ℃ and a load of 2.16kg, and the results are shown in the following table:

as can be seen from the above table, the tensile yield stress of the polypropylene plastics prepared in examples 1-3 is 25.35-26.32MPa, the flexural modulus is 1483.59-1488.27MPa, and the melt flow rate is 27.53-27.7 g.10 min-, compared with the polypropylene prepared in comparative example 3, the polypropylene plastic prepared in the invention has no influence on the mechanical properties and the processability, and the mechanical properties are enhanced to a certain extent compared with pure polypropylene; as can be seen from the above table, the notched impact strength of the polypropylene plastics prepared in examples 1-3 is 10.63-10.78 kJ.m < -2 >, which is significantly improved compared with that of comparative example 3, indicating that the polypropylene plastics prepared in the invention have high toughness; compared with comparative example 1, the toughness of the polypropylene can be improved after the polypropylene is modified by the modifier; compared with the comparative example 2, the filler can be dispersed in the PP matrix after being modified, and can interact with the modified PP molecular chain, so that the effect of the filler and the matrix is improved, and the reinforcing and toughening effects of the filler can be exerted.

The preferred embodiments of the invention disclosed above are intended to be illustrative only. The preferred embodiments are not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims (5)

1. The high-toughness polypropylene plastic is characterized by being prepared from the following raw materials in parts by weight: 70-80 parts of modified polypropylene, 15-20 parts of reinforcing filler and 0.8-1 part of antioxidant;

the polypropylene plastic is prepared by the following method:

the modified polypropylene is firstly added into an open type heat mill with the double-roller temperature of 170-180 ℃, the antioxidant and the reinforcing filler are sequentially added after the modified polypropylene is melted and coated on the rollers, and the mixture is uniformly mixed and then extruded and granulated by a double-screw extruder to prepare the high-toughness polypropylene plastic.

2. The high tenacity polypropylene plastic material according to claim 1, wherein said modified polypropylene is prepared by the following method:

s1, sequentially adding pentaerythritol, 4-hydroxycrotonic acid and toluene into a four-necked bottle provided with a stirrer, a thermometer, a water separator and an air guide pipe, stirring for 5min, adding a polymerization inhibitor, a catalyst and a decolorizing agent, heating and maintaining the temperature at 80-90 ℃ for reflux reaction, testing the residual acid value of a reaction solution to a target range, finishing the reaction, cooling to room temperature, sequentially washing and extracting with a NaCl solution and a sodium carbonate solution, collecting an oil layer, neutralizing the pH value to 7.0 with a sodium hydroxide solution, washing with a 5% sodium chloride solution, collecting the oil layer, adding anhydrous sodium sulfate, drying overnight, filtering, and distilling at 40-50 ℃ under reduced pressure to remove the solvent to obtain a modifier;

s2, performing surface treatment on the polypropylene surface by using air plasma, wherein the treatment voltage is 70V, the treatment time is 4-5min, and the gas flow rate is 100 mL/min; the treated polypropylene was mixed with the modifier prepared above according to a ratio of 25: 1, putting the mixture into a torque rheometer for melt grafting at the rotating speed of 60r/min and the blending temperature of 180 ℃ for 15-18 min;

s3, completely dissolving the molten mixture in xylene at 140 ℃, precipitating with acetone, filtering, repeating the operation for 3-4 times, and drying the product in a vacuum drying oven at 80 ℃ for 2d to obtain the modified polypropylene.

3. A high-toughness polypropylene plastic as claimed in claim 2, wherein in step S1, the ratio of the amounts of pentaerythritol, 4-hydroxycrotonic acid and toluene is 1: 4.2: 2; the dosage of the catalyst is 4 percent of the mass of the pentaerythritol, the dosage of the polymerization inhibitor is 3.5 percent of the mass of the acrylic acid, the dosage of the decolorizing agent is 3 percent of the dosage of the pentaerythritol, and the target acid value is less than 1.

4. A high tenacity polypropylene plastic as claimed in claim 1, wherein said reinforcing filler is prepared by the process of:

(1) mixing graphene oxide and nano silicon dioxide according to a mass ratio of 10: 6-7, mixing according to a solid-liquid ratio of 1 g: dispersing 30mL of the aqueous solution in 3% by volume of acetic acid to form a dispersion liquid;

(2) according to the solid-liquid ratio of 1 g: adding 10mL of sebacic acid into methanol, stirring for 10-15min, and mixing with the dispersion according to a volume ratio of 1: 1, mixing, and mechanically stirring at 35-40 ℃ for reaction for 22-24 h;

(3) after the reaction is finished, washing the mixture by using 0.1mol/L NaOH solution, distilled water, 0.1mol/L HCl solution, distilled water and ethanol in sequence, and drying the mixture in a vacuum drying oven at the temperature of 30 ℃ for 24 hours to obtain the reinforced filler.

5. The process for preparing a high toughness polypropylene plastic as claimed in claim 1, wherein said process comprises the following steps:

the modified polypropylene is firstly added into an open type heat mill with the double-roller temperature of 170-180 ℃, the antioxidant and the reinforcing filler are sequentially added after the modified polypropylene is melted and coated on the rollers, and the mixture is uniformly mixed and then extruded and granulated by a double-screw extruder to prepare the high-toughness polypropylene plastic.