Random copolymer transparent polypropylene special material and preparation method thereof

Abstract

The application provides two kinds of random copolymer transparent polypropylene special materials and preparation methods thereof. By adding modified carbon nanotubes obtained by sequentially performing surface modification on purified carbon nanotubes through a coupling agent, polydopamine and gelatin, the compatibility of the carbon nanotubes and the polypropylene can be significantly improved. In combination with random copolymer polypropylene resin and other additives, the transparency and mechanical properties of the polypropylene special material can be significantly improved, and the application requirements in the fields of high-end medical materials, medical super-soft materials and the like can be met.

Description

TECHNICAL FIELD

[0001] The present application relates to the chemical industry, in particular to a random copolymer transparent polypropylene special material and a preparation method thereof. BACKGROUND

[0002] In recent years, polypropylene has developed rapidly, and there are many types of products. People are no longer satisfied with its use as a general-purpose material, and the market demand for special materials is increasing, and special materials are being used more and more widely. In the face of changing market demand, developing new products to meet market demand, enhancing product profitability, and increasing market share have become the primary work of each manufacturer. After investigation, transparent polypropylene has developed rapidly in recent years, and the market demand reached 150 tons / year in 2021, with an annual increase of 5-7%, becoming one of the fastest growing varieties in polypropylene products.

[0003] Compared with ordinary polypropylene, transparent polypropylene has higher toughness, rigidity, heat resistance and chemical resistance, and its excellent transparency and gloss can be comparable to typical transparent materials, and can be widely used in household products, packaging and medical fields. Transparent polypropylene is mainly divided into high-index, medium-index and low-index transparent PP, which is respectively applied to injection molding, hollow molding, thermoforming and injection-stretch-blow molding fields. The annual demand for medium-index transparent polypropylene is about 100,000 tons, which is widely used in household products, packaging and other fields. At present, high-end sanitary materials and medical super-soft random copolymer polypropylene fiber materials in China mainly rely on imports (such as RP1669 of BASF).

[0004] In 1991, Japanese scholar Iijima discovered carbon nanotubes. Carbon nanotubes, as the name implies, are tubular objects with a certain degree of helicity formed by rolling graphite layers around a central axis, and the ends of the tubes are generally sealed by pentagonal hemispherical lattice. Each carbon atom in the carbon nanotube is connected to three adjacent carbon atoms to form a hexagonal lattice structure, but the hexagonal lattice structure in the carbon nanotube generally produces a certain bending to form a spatial topological structure, so it is mainly sp2 hybridization and contains sp3 hybridization. Carbon nanotubes are generally divided into single-walled carbon nanotubes and multi-walled carbon nanotubes. The length of single-walled carbon nanotubes can reach several tens of microns, and the diameter is between zero point several nanometers and several nanometers. The length of multi-walled carbon nanotubes can reach several millimeters, and the diameter is between several nanometers and several tens of nanometers. The interlayer spacing of graphite remains fixed at about 0.34 nm.

[0005] Carbon nanotubes are formed by rolling graphite layers around a central axis, and the structure and properties are different due to different rolling methods. When the carbon nanotube is rolled, there may be an angle between the nanotube axis and the fixed hexagonal lattice in the graphite layer, i.e. the helix angle (such as Figure 1)。Carbon nanotubes can exhibit both semiconducting and metallic properties depending on the diameter and the helicity: when (n~m) is an integer multiple of 3, it exhibits metallic properties, and vice versa, it exhibits semiconducting properties, so carbon nanotubes have excellent performance due to its unique structure. It has ideal elasticity and extremely high mechanical strength, carbon nanotubes can not only withstand huge axial tension, but also can withstand huge radial deformation, the tensile strength reaches 50~200GPa, which is 100 times that of steel, the bending strength can reach 14.2GPa, the elastic modulus can reach 1.8TPa, which is equivalent to the elastic modulus of diamond, about 5 times that of steel, and the density is only 1 / 6 of that of steel. In addition, carbon nanotubes have high thermal stability and chemical stability, and their excellent heat conduction capacity, superconducting performance and optical performance have attracted great attention, and their applications have involved composite materials, nanoelectronic devices, catalyst supports, electrode materials, hydrogen storage materials and other aspects. Carbon nanotubes can exhibit their elasticity by volume change, so they can withstand tension strain greater than 40% without exhibiting plastic deformation, brittle behavior or bond rupture, so when used in composite materials, carbon nanotubes can be used to greatly absorb energy and increase strength, toughness and other excellent mechanics, making carbon nanotubes the most promising research hotspot in the field of composite materials. The research of carbon nanotube composite materials has become an extremely important field and has received extensive attention and research.

[0006] However, due to the easy entanglement or aggregation of carbon nanotubes into bundles, the surface of carbon nanotubes is relatively "inert" compared with other nanoparticles, and the dispersion in common organic solvents is low, and it is difficult to disperse uniformly in polymers, which greatly restricts the research on its application performance. In order to improve the uniformity of carbon nanotubes in polymers, at present, surface chemical reaction modification, polymer coating modification, surfactant modification and other methods are mainly used to modify carbon nanotubes. Surface chemical reaction modification refers to introducing some suitable groups on the surface of carbon nanotubes, so that chemical reaction occurs on the surface of carbon nanotubes, and chemical bonds are generated between the surface and the polymer. Through this method, the dispersion can be improved, and the solubility of carbon nanotubes can be improved. At present, the modification of the surface of carbon nanotubes has become a research hotspot of polymer / carbon nanotube composites.

[0007] And how to apply carbon nanotubes to ethylene-propylene random copolymer transparent polypropylene special material to fully exert the super mechanical properties of carbon nanotubes, so as to prepare a random copolymer transparent polypropylene special material with high transparency, high toughness and high rigidity, which becomes a technical problem to be solved in the art.

[0008] As disclosed in Chinese patent document CN113480802A, a high-performance flame-retardant antistatic polypropylene includes the following raw materials in parts by mass: polypropylene 50-70 parts, glass fiber 10-30 parts, carbon nanotube 5-20 parts, modified high molecular antistatic agent 5-15 parts, maleic anhydride grafted compatibilizer 3-8 parts, flame retardant 3-10 parts, silane coupling agent 1-5 parts, and dispersant 0.1-3 parts. The high-performance flame-retardant antistatic polypropylene enhances the mechanical properties and weather resistance of the polypropylene material, has high specific strength, light weight, corrosion resistance, good flame-retardant effect with less smoke and no toxic gas, and good antistatic performance. However, due to the easy entanglement or aggregation of carbon nanotubes into bundles, the surface of carbon nanotubes is relatively "inert" compared to other nanoparticles, and it is difficult to uniformly disperse in the polymer, and it is easy to agglomerate in the polymer, thus increasing the brittleness and significantly reducing the toughness of the polypropylene material.

[0009] Chinese patent document CN103408821A discloses a polyethylene / fullerene nanocomposite material and a preparation method thereof. The material is prepared from the following raw materials in parts by weight: fullerene (carbon nanotube) 0.05-5 parts by weight, and polyethylene 95-99.95 parts by weight. The preparation method is to directly add the dried fullerene into high-density polyethylene for melt blending to prepare a polyethylene nanocomposite material with high thermal stability. However, due to the easy entanglement or aggregation of carbon nanotubes into bundles, the surface of carbon nanotubes is relatively "inert" compared to other nanoparticles, and it is difficult to uniformly disperse in the polymer, and it is easy to agglomerate in the polymer, which further leads to the comprehensive performance of the composite material not being improved and the tensile strength being decreased, which shows that simple mechanical blending is difficult to uniformly disperse carbon nanotubes in the polypropylene matrix.

[0010] Chinese patent document CN103011131A discloses a preparation method of carbon nanotubes modified by coupling agent. Specifically, the coupling agent is hydrolyzed in alcohol and water to obtain active functional groups, and these active functional groups are used for impregnation reaction with carbon nanotubes, so that the coupling agent migrates from the polymer to the surface of the filler, hydrolysis and condensation reaction is completed, and long-chain alkyl groups are grafted on the surface of the carbon nanotubes. Although this method solves the problems of easy aggregation and entanglement of carbon nanotubes and difficult dispersion to some extent, the chemical inertness of carbon nanotubes leads to the difficulty of grafting groups on the surface of carbon nanotubes even after acidification treatment, and it is difficult to form chemical action between the coupling agent and the carbon nanotubes, which leads to the modification effect of carbon nanotubes not reaching the expected effect.

[0011] Chinese patent document CN109052370A discloses a carbon nanotube surface modification method, which sequentially adopts a composite modification method of highly oxidative method, polymer coating and coupling agent treatment to perform surface treatment on the carbon nanotube. The modified carbon nanotube can be stably dispersed in a solvent, and the compatibility with the polymer is improved. However, the dispersibility of the carbon nanotube after surface modification still needs to be improved.

[0012] Chinese patent document CN109749096A discloses a preparation method of carbon nanotube modified gelatin hydrogel. The carbon nanotube array is modified by using a methacrylate polymer with an unsaturated group terminal to reduce the agglomeration caused by the van der Waals force between the carbon nanotubes. The ester group on the modified carbon nanotube array is connected to the amino group or the hydroxyl group in the gelatin through a covalent bond, and the unsaturated bond in the methacrylate polymer grafted on the carbon nanotube is crosslinked, so that the carbon nanotube modified gelatin hydrogel with good mechanical properties is obtained. However, the gelatin grafting rate in the scheme is low, and the modification effect of the carbon nanotube does not reach the expectation.

[0013] Therefore, how to apply the carbon nanotube to the polypropylene fiber material to fully exert the super mechanical properties of the carbon nanotube, so as to prepare a high-toughness, high-rigidity and high-fluidity polypropylene fiber material for high-end sanitary materials and medical super-soft atactic copolymer, has become a technical problem to be solved in the field. SUMMARY

[0014] In view of the above defects and improvement needs of the prior art, the present application provides an atactic copolymer transparent polypropylene special material and a preparation method thereof. By modifying the carbon nanotube, the compatibility of the carbon nanotube and the polypropylene resin is improved, and the synergistic effect of the modified carbon nanotube, the polypropylene resin and the auxiliary agent is utilized to improve the comprehensive properties of the polypropylene special material, such as the mechanical properties, toughness, rigidity and fluidity, so that the application requirements in the fields of high-end sanitary materials and medical super-soft materials can be met.

[0015] To achieve the above-mentioned purpose, the present application provides an atactic copolymer transparent polypropylene special material, which comprises the following components in the following amounts: atactic copolymer polypropylene resin 95wt%-99.5wt%; modified carbon nanotube 0.1wt%-1wt%; transparent nucleating agent 0.1wt%-1wt%; and composite auxiliary agent 0.2wt%-3wt%.

[0016] The modified carbon nanotube is obtained by sequentially modifying the carbon nanotube purified by the oxidation method with a coupling agent, polydopamine and gelatin.

[0017] To achieve the above object, the application further provides another random copolymer transparent polypropylene special material, which comprises the following components in the following contents: random copolymer polypropylene resin 90wt%-99wt%, toughening master batch 1wt%-10wt%; the toughening master batch comprises the following components in the following contents: random copolymer polypropylene resin 55wt%-96wt%, modified carbon nanotube 0.5wt%-5wt%, transparent nucleating agent 0.5wt%-10wt% and composite auxiliary agent 3wt%-30wt%.

[0018] The modified carbon nanotube is obtained by sequentially modifying the surface of the carbon nanotube purified by the oxidation method with a coupling agent, polydopamine and gelatin.

[0019] Optionally, in the above two random copolymer transparent polypropylene special materials, the carbon nanotube is purified by using a mixed solution of potassium permanganate and concentrated sulfuric acid when the oxidation method is used to purify the carbon nanotube. By using the oxidation method to purify the carbon nanotube, hydroxyl groups can be introduced onto the surface of the carbon nanotube.

[0020] Optionally, in the above two random copolymer transparent polypropylene special materials, the composite auxiliary agent is at least one selected from an antioxidant, an antistatic agent and an acid scavenger.

[0021] Optionally, in the above second random copolymer transparent polypropylene special material, the toughening master batch comprises the following components in the following contents: random copolymer polypropylene resin 55wt%-96wt%, modified carbon nanotube 0.5wt%-5wt%, transparent nucleating agent 0.5wt%-10wt%, antistatic agent 1wt%-10wt%, acid scavenger 1wt%-10wt% and antioxidant 1wt%-10wt%.

[0022] Optionally, in the above first random copolymer transparent polypropylene special material, the random copolymer transparent polypropylene special material comprises the following components in the following contents: random copolymer polypropylene resin 95wt%-99.5wt%, modified carbon nanotube 0.1wt%-1wt%, transparent nucleating agent 0.1wt%-1wt%, antistatic agent 0.1wt%-0.5wt%, acid scavenger 0.1wt%-0.5wt% and antioxidant 0.1wt%-2wt%.

[0023] Optionally, in the two random copolymer transparent polypropylene special materials above, the antioxidants, the antistatic agents, the acid scavengers and the transparent nucleating agents are not particularly limited and can be selected from conventional ones in the industry. The antioxidants recommended by the present application are phenolic antioxidants, such as at least one of 2,6-di-tert-butyl-4-methylphenol, 4-hydroxymethyl-2,6-di-tert-butylphenol, β-(4-hydroxy-3,5-di-tert-butylphenyl)propionic acid n-octadecyl ester, 4,4'-dihydroxydiphenyl, butylated styrenated cresol, 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2,2'-methylenebis(4-ethyl-6-tert-butylphenol), 2,2'-methylenebis(4-methyl-6-cyclohexylphenol), 2,2'-methylenebis(4-methyl-6-(α-methylcyclohexyl)phenol), 4,4'-butylidenebis(3-methyl-6-tert-butylphenol), 4,4'-methylenebis(2,6-di-tert-butylphenol) and 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, antioxidant 1010, antioxidant 168, antioxidant 1076, antioxidant 164, etc.

[0024] The antistatic agents can be at least one of alcohol ether phosphoric acid monoester, alkyl phosphate diethanolammonium salt, stearyl amido propyl-β-hydroxyethyl quaternary ammonium nitrate, (3-lauroylamidopropyl)trimethyl methyl sulfate ammonium, Antistat 68, SGK-03 type antistatic agent, ASA-10, octylphenol polyoxyethylene ether, polyoxyethylene stearate and monoglyceride, etc.

[0025] The acid scavengers can be at least one of calcium stearate, hydrotalcite, zinc oxide, etc.

[0026] The transparent nucleating agents can be at least one of aryl phosphate transparent nucleating agent, sorbitol transparent nucleating agent, carboxylic acid metal salt transparent nucleating agent, dehydroacid and its salt transparent nucleating agent, branched acid amine transparent nucleating agent, etc.

[0027] Optionally, in the two random copolymer transparent polypropylene special materials above, the random copolymer polypropylene resin is an ethylene-propylene copolymer resin; preferably, the ethylene-propylene copolymer resin has a melt index of 6-11 g / 10 min and an ethylene content of 2wt%-5wt%; more preferably, the ethylene-propylene copolymer resin has a melt index of 7-9 g / 10 min and an ethylene content of 2wt%-3wt%.

[0028] Optionally, the two kinds of random copolymerized transparent polypropylene special material provided by the present application, the coupling agent is selected from silane coupling agent or titanate coupling agent, such as vinyl triethoxysilane, gamma-methacryloxypropyl trimethoxysilane (KH-550), methyl ethyl silane, 1,1,2, -trimethyl propyl trichlorosilane, vinyl trimethoxysilane, vinyl tri(β-methoxyethoxy) silane, isopropyl dioleic acyl oxygen (dioctyl phosphoric acid acyl oxygen), isopropyl dioleic acyl oxygen (dioctyl phosphoric acid acyl oxygen) titanate and the like.

[0029] The preparation method of the two kinds of random copolymerized transparent polypropylene special material provided by the present application is not limited, and the conventional method in the industry can be used. For example, the first kind of random copolymerized transparent polypropylene special material can be prepared by the following method:

[0030] After the random copolymerized polypropylene resin, the modified carbon nanotube, the transparent nucleating agent and the composite auxiliary agent are uniformly mixed in the low-speed mixer (for example, mixed for 3-5 min at 20-30 ℃), they are added into the double screw extruder for melt extrusion, the extruded material is cooled, air dried and granulated, and the random copolymerized transparent polypropylene special material is obtained; preferably, the extrusion temperature is 200-210 ℃, and the screw rotation speed is 200-300 rpm.

[0031] The second kind of random copolymerized transparent polypropylene special material provided by the present application can be prepared by the following method:

[0032] After the random copolymerized polypropylene resin, the modified carbon nanotube, the transparent nucleating agent and the composite auxiliary agent are uniformly mixed in the high-speed mixer (for example, mixed for 3-5 min at room temperature), they are put into the double screw extruder for melt extrusion, and the toughening master batch is obtained; preferably, the extrusion temperature is 160-190 ℃, and the screw rotation speed is 55-150 rpm.

[0033] After the random copolymerized polypropylene resin and the toughening master batch are uniformly mixed in the low-speed mixer, they are put into the double screw extruder for melt extrusion, the extruded material is cooled, air dried and granulated, and the random copolymerized transparent polypropylene special material is obtained; preferably, the extrusion temperature is 200-210 ℃, and the screw rotation speed is 200-300 rpm.

[0034] Optionally, in the preparation method of the two kinds of random copolymerized transparent polypropylene special material provided by the present application, the preparation of the modified carbon nanotube comprises the following steps:

[0035] Purification: the carbon nanotube is dispersed in the oxidizing agent for reflux reaction, after the reaction is completed, it is separated, washed to neutral and vacuum dried, and the purified carbon nanotube is obtained;

[0036] The coupling agent is added to the purified carbon nanotubes and dispersed in ethanol, and then refluxed. After the reaction is completed, the ethanol is removed, and the carbon nanotubes modified by the coupling agent are obtained.

[0037] The coupling agent is added to the purified carbon nanotubes and dispersed in ethanol, and then refluxed. After the reaction is completed, the ethanol is removed, and the carbon nanotubes modified by the coupling agent are obtained.

[0038] The coupling agent is added to the purified carbon nanotubes and dispersed in ethanol, and then refluxed. After the reaction is completed, the ethanol is removed, and the carbon nanotubes modified by the coupling agent are obtained.

[0039] Optionally, in the preparation process of the modified carbon nanotubes, the mass / volume ratio of the carbon nanotubes to the oxidizing agent is 25 mg:(1-10) mL; preferably, the oxidizing agent is a mixed solution of potassium permanganate and concentrated sulfuric acid with a mass ratio of (1-2):(1-2).

[0040] Optionally, in the preparation process of the modified carbon nanotubes, in the purification step, the carbon nanotubes are placed in the oxidizing agent, then ultrasonic treatment is performed at room temperature for 2-3 h until they are uniformly dispersed, then reflux reaction is performed at 120-130°C for 3-5 h, then filtration, deionized water washing to neutral, and drying to constant weight under vacuum are performed, and the purified carbon nanotubes are obtained.

[0041] Optionally, in the preparation process of the modified carbon nanotubes, the outer diameter of the carbon nanotubes is 20-30 nm, the length is 10-30 μm, the density is 2-3 g / m 3 , and the surface area is greater than 110 m 2 / g.

[0042] Optionally, in the preparation process of the modified carbon nanotubes, in the coupling agent modification step, the mass ratio of the purified carbon nanotubes to the coupling agent is 5:(1-10).

[0043] Optionally, in the preparation process of the modified carbon nanotubes, in the coupling agent modification step, the coupling agent and the purified carbon nanotubes are added to ethanol, ultrasonic treatment is performed at room temperature for 1-2 h, then reflux is performed at 70-80°C for 2-3 h, and then the ethanol is removed, and the carbon nanotubes modified by the coupling agent are obtained.

[0044] Optionally, in the preparation process of the modified carbon nanotube, in the polydopamine modification step, the coupling agent modified carbon nanotube is dispersed in the tris-buffer solution at room temperature by ultrasonic, then the polydopamine is added and reacted for 3-5 hours under stirring, and the obtained solid is washed with deionized water for 2-5 times to neutral, so as to obtain the coupling agent and polydopamine modified carbon nanotube.

[0045] Optionally, in the preparation process of the modified carbon nanotube, in the polydopamine modification step, the mass ratio of the coupling agent modified carbon nanotube to the polydopamine is 5:(1-10); and the mass-volume ratio of the coupling agent modified carbon nanotube to the tris-buffer solution is 5mg:(1-10)mL.

[0046] Optionally, in the preparation process of the modified carbon nanotube, in the gelatin modification step, the gelatin is dissolved in deionized water to obtain a gelatin aqueous solution; the coupling agent and polydopamine modified carbon nanotube are added into the deionized water, and then mixed with the gelatin aqueous solution under stirring for 20-26 hours, and the obtained solid is centrifuged and washed with deionized water, and then freeze-dried for 20-26 hours, so as to obtain the modified carbon nanotube.

[0047] Optionally, in the preparation process of the modified carbon nanotube, in the gelatin modification step, the mass-volume ratio of the coupling agent and polydopamine modified carbon nanotube to the deionized water, and the mass-volume ratio of the gelatin to the deionized water in the gelatin aqueous solution are not limited, and can be adjusted according to the actual situation, that is, the coupling agent and polydopamine modified carbon nanotube can be uniformly dispersed in the deionized water, and the gelatin can be dissolved in the deionized water, and the mass ratio of the coupling agent and polydopamine modified carbon nanotube to the gelatin is 5:(1-10).

[0048] In the preparation process of the modified carbon nanotube, the reaction time of each step can be adjusted according to the actual reaction conditions (such as the amount of feed, reaction temperature, etc.).

[0049] Compared with the prior art, the present application has the following advantages:

[0050] Beneficial effect 1: the first random copolymerization transparent polypropylene special material provided by the application can significantly improve the compatibility of carbon nanotubes and random copolymerization polypropylene resin by adding modified carbon nanotubes which are surface modified by coupling agent, polydopamine and gelatin in sequence from purified carbon nanotubes, so that the mechanical properties of carbon nanotubes can be fully utilized, and the polypropylene special material obtained by combining with the synergistic effect of other additives has excellent comprehensive performance such as mechanical properties, toughness, rigidity and high fluidity, which can meet the application requirements in high-end medical materials, medical super-soft and other fields. The second random copolymerization transparent polypropylene special material provided by the application can further significantly improve the compatibility of carbon nanotubes and polypropylene by adding toughening masterbatch formed by part of random copolymerization polypropylene resin, modified carbon nanotubes which are surface modified by coupling agent, polydopamine and gelatin in sequence from purified carbon nanotubes and additives. Compared with existing polypropylene special materials, the impact strength and bending modulus of the two random copolymerization transparent polypropylene special materials provided by the application are significantly improved.

[0051] Beneficial effect 2: in the modified carbon nanotubes provided by the application, the purified carbon nanotubes are first modified by coupling agent, then modified by polydopamine to combine polydopamine with carbon nanotubes, and finally grafted with gelatin on the surface of carbon nanotubes through polydopamine; one end of the coupling agent is firmly combined with the carbon nanotubes, and the other end is combined with the random copolymerization polypropylene resin. This modification method does not damage the structure of carbon nanotubes itself, so that the modified carbon nanotubes with complete structure can be obtained. The modified carbon nanotubes are added to the random copolymerization polypropylene resin matrix to improve the compatibility of carbon nanotubes and random copolymerization polypropylene, and the steric hindrance effect of the introduced long carbon chain can avoid the agglomeration of carbon nanotubes. At the same time, carbon nanotubes have excellent mechanical properties and play the role of physical crosslinking point, thus having the effects of reinforcement and toughening, and combining with other additives, the comprehensive performance of the random copolymerization transparent polypropylene special material can be significantly improved.

[0052] Beneficial effect 3: the second random copolymerization transparent polypropylene special material provided by the application can further improve the compatibility of carbon nanotubes and polymers by first preparing toughening masterbatch from modified carbon nanotubes, and then mixing into random copolymerization polypropylene resin for secondary dispersion. BRIEF DESCRIPTION OF DRAWINGS

[0053] Figure 1 It is a schematic diagram of the curl structure of carbon nanotubes. DETAILED DESCRIPTION

[0054] The application will be described in detail below by way of examples. It is necessary to point out here that the following examples are only used to further illustrate the application and cannot be understood as limiting the protection scope of the application, and those skilled in the art can make some non-essential improvements and adjustments to the application according to the above description of the application.

[0055] If the specific experimental steps or conditions are not indicated in the examples, the operations or conditions can be carried out according to the conventional experimental steps described in the literature in the art. If the reagents or instruments used are not indicated by the manufacturer, they are all conventional reagent products that can be obtained by purchase on the market.

[0056] Example 1

[0057] This example provides a random copolymer transparent polypropylene special material, and the preparation method is as follows:

[0058] (I) Preparation of modified carbon nanotubes

[0059] Purification: 250 mg of carbon nanotubes were dispersed in 10 mL of oxidizing agent, ultrasonically treated at room temperature for 2 h, and then refluxed at 120-130°C for 4 h until the reaction was completed. After filtration, the obtained solid was washed with deionized water until neutral, and then vacuum dried to constant weight to obtain the purified carbon nanotubes. The oxidizing agent was a mixed solution of potassium permanganate and concentrated sulfuric acid with a mass ratio of 1:1.

[0060] Coupling agent modification: 50 mg of silane coupling agent (KH-570) and 250 mg of the above purified carbon nanotubes were added to ethanol, ultrasonically dispersed and treated for 2 h, and then refluxed at 70-80°C for 3 h until the reaction was completed. Ethanol was removed by distillation to obtain the coupling agent modified carbon nanotubes.

[0061] Polydopamine modification: 250 mg of the above coupling agent modified carbon nanotubes were ultrasonically dispersed in 50 mL of tris-buffer, and then 50 mg of polydopamine PODA was added. After stirring for 4 h, the obtained solid was centrifuged and washed with deionized water until neutral to obtain the coupling agent and polydopamine modified carbon nanotubes.

[0062] Gelatin modification: 50 mg of gelatin was dissolved in 50 mL of deionized water to obtain a gelatin solution; 250 mg of the above coupling agent and polydopamine modified carbon nanotubes were dispersed in 100 mL of deionized water, and then mixed with the gelatin solution by stirring for 24 h until the reaction was completed. After centrifugation, the obtained solid was washed with deionized water for 3 times, and then freeze-dried to obtain the modified carbon nanotubes.

[0063] (II) Preparation of random copolymer transparent polypropylene special material

[0064] The materials were weighed according to the following weight contents:

[0065] Modified carbon nanotube 1 wt%

[0066] Modified carbon nanotube 1 wt%

[0067] Transparent nucleating agent 1 wt%

[0068] Composite aid 3 wt% (antistatic agent 1 wt%; acid scavenger 1 wt%, primary antioxidant 0.5 wt% and secondary antioxidant 0.5 wt%).

[0069] After mixing the above materials in a low speed mixer at 20°C for 3 minutes, melt extrusion was carried out in a twin-screw extruder, with an extrusion temperature of 200-210°C and a screw rotation speed of 250 rpm. The extruded material was then cooled, air-dried and pelletized to obtain the random copolymer transparent polypropylene special material.

[0070] Example 2-10

[0071] Example 2-10 is similar to Example 1, except for the different parameters and raw materials, as shown in Table 1 and Table 2 below.

[0072] Table 1 Preparation parameters of modified carbon nanotubes

[0073]

[0074] Note: methyl ethyl silane is denoted as A, 1,1,2-trimethylpropyltrichlorosilane is denoted as B.

[0075] Table 2 Preparation parameters of random copolymer transparent polypropylene special material

[0076]

[0077]

[0078] Note: the ratio of primary antioxidant and secondary antioxidant is the same in each example.

[0079] Example 11

[0080] This example provides a random copolymer transparent polypropylene special material, and the preparation method is as follows:

[0081] (I) Preparation of modified carbon nanotubes

[0082] The same as Example 1.

[0083] (II) Preparation of toughening masterbatch

[0084] Each material was weighed according to the following weight content:

[0085] Random copolymer polypropylene resin 95.5 wt%

[0086] Modified carbon nanotube 0.5 wt%

[0087] Transparent nucleating agent 1 wt%

[0088] Antistatic agent 1 wt%

[0089] Acid scavenger 1 wt%

[0090] Antioxidant 1 wt% (primary antioxidant 0.5 wt% and secondary antioxidant 0.5 wt%)

[0091] In the above, the transparent nucleating agent is NA-21; the antistatic agent is glycerol monostearate; the acid scavenger is calcium stearate; the primary antioxidant is Irganox® 1010, and the secondary antioxidant is Irganox® 168.

[0092] After mixing the above materials in a high-speed mixer for 4 minutes, the mixture is put into a twin-screw extruder for extrusion granulation. The screw rotation speed of the twin-screw extruder is 100 rpm, and the temperature is 160-190°C. The toughening masterbatch is obtained.

[0093] (III) Preparation of the random copolymerized transparent polypropylene special material

[0094] The materials are weighed according to the following weight content:

[0095] Random copolymerized polypropylene resin 90 wt%

[0096] Toughening masterbatch 10 wt%

[0097] The random copolymerized polypropylene resin in the above step (II) and step (III) is an ethylene-propylene copolymer resin, and the melt index thereof is 6 g / 10 min, and the ethylene content is 2 wt%.

[0098] After mixing the above materials in a low-speed mixer at 20°C for 3 minutes, the mixture is put into a twin-screw extruder for melt extrusion. The extrusion temperature is between 200-210°C, and the screw rotation speed is 250 rpm. Then the extruded material is cooled, air-dried, and cut into particles. The random copolymerized transparent polypropylene special material is obtained.

[0099] Examples 12-20

[0100] Examples 12-20 are similar to Example 11, except that some parameters and raw materials are different. The specific parameters are shown in Table 3 below.

[0101] Table 3

[0102]

[0103]

[0104] Note: The properties of the ethylene-propylene copolymer resins involved in Examples 11-20, and the modified carbon nanotubes, transparent nucleating agent, antistatic agent, acid scavenger and antioxidant are the same as those in Examples 1-10, respectively.

[0105] Comparative Example 1

[0106] This comparative example is similar to Example 5, except that the modified carbon nanotubes used are different. The modified carbon nanotubes used in this comparative example are prepared as follows:

[0107] Purification: 250 mg of carbon nanotubes are dispersed in 50 mL of oxidizing agent, and after ultrasonic treatment for 2 h at room temperature, the reaction is refluxed at 120-130 °C for 4 h until the reaction is completed. The obtained solid is washed with deionized water until neutral, and dried to constant weight under vacuum to obtain the purified carbon nanotubes. The oxidizing agent is a mixed solution of potassium permanganate and concentrated sulfuric acid in a mass ratio of 1:1;

[0108] Coupling agent modification: 250 mg of silane coupling agent (1,1,2-trimethylpropyltrichlorosilane) and 250 mg of the above purified carbon nanotubes are added to ethanol, and after ultrasonic dispersion treatment for 2 h, the reaction is refluxed at 70-80 °C for 2 h until the reaction is completed. The ethanol is removed by distillation to obtain the modified carbon nanotubes.

[0109] Comparative Example 2

[0110] This comparative example is similar to Example 15, except that the modified carbon nanotubes used are different. The modified carbon nanotubes used in this comparative example are prepared in the same way as the modified carbon nanotubes in Comparative Example 1.

[0111] Comparative Example 3

[0112] This comparative example provides a random copolymerized transparent polypropylene special material, which is prepared as follows:

[0113] Each material is weighed according to the following weight content:

[0114] Random copolymerized polypropylene resin 95 wt%

[0115] Carbon nanotubes 1 wt%

[0116] Transparent nucleating agent 1 wt%

[0117] Composite auxiliary agent 3 wt% (antistatic agent 1 wt%; acid scavenger 1 wt%, primary antioxidant 0.5 wt% and secondary antioxidant 0.5 wt%).

[0118] The random copolymerization polypropylene resin is an ethylene-propylene copolymer resin, the melt index of which is 6 g / 10 min, and the ethylene content is 2 wt%; the transparent nucleating agent is NA-21, the antistatic agent is monoglyceride; the acid scavenger is calcium stearate; the main antioxidant is 1010, and the auxiliary antioxidant is 168; the outer diameter of the carbon nanotube is 20 nm, the length is 10 μm, the density is 2 g / m 3 , and the surface area is 150 m 2 / g.

[0119] After the above materials are mixed in a low-speed mixer at 20 °C for 3 minutes, they are subjected to melt extrusion in a twin-screw extruder, the extrusion temperature is between 200-210 °C, and the screw rotation speed is 250 rpm, then the extruded material is cooled, air-dried, and pelletized to obtain the random copolymerization transparent polypropylene special material.

[0120] Comparative Example 4

[0121] This comparative example provides a random copolymerization transparent polypropylene special material, which is prepared according to the following method:

[0122] (I) Preparation of modified carbon nanotubes

[0123] Purification: 250 mg of carbon nanotubes are dispersed in 10 mL of oxidizing agent, ultrasonic treatment is performed at room temperature for 2 h, then reflux reaction is performed at 120-130 °C for 4 h until the reaction is completed, then filtration is performed, the obtained solid is washed with deionized water until it is neutral, and vacuum drying is performed until the constant weight to obtain the purified carbon nanotubes. The oxidizing agent is a mixed solution of potassium permanganate and concentrated sulfuric acid with a mass ratio of 1:1; the outer diameter, length, density, and surface area of the carbon nanotubes are the same as in Example 1.

[0124] Polydopamine modification: 250 mg of the above coupling agent modified carbon nanotubes are ultrasonically dispersed in 50 mL of tris-buffer, then 50 mg of polydopamine PODA is added, and reaction is performed under stirring for 4 h, then centrifugation is performed, and the obtained solid is washed with deionized water until it is neutral to obtain the polydopamine modified carbon nanotubes.

[0125] Gelatin modification: 50 mg of gelatin is dissolved in 50 mL of deionized water to obtain a gelatin solution; 250 mg of the above polydopamine modified carbon nanotubes are dispersed in 100 mL of deionized water, then the gelatin solution is mixed by stirring for 24 h until the reaction is completed, then centrifugation is performed, the obtained solid is washed with deionized water for 3 times, and then freeze-drying is performed to obtain the polydopamine and gelatin modified carbon nanotubes.

[0126] Coupling agent modification: 50 mg of silane coupling agent (KH-570) and 250 mg of the above polydopamine and gelatin modified carbon nanotubes are added into ethanol, ultrasonic dispersion treatment is performed for 2 h, then reflux reaction is performed at 70-80 °C for 3 h until the reaction is completed, then ethanol is removed by distillation to obtain the modified carbon nanotubes.

[0127] (ii) Preparation of the random copolymerized transparent polypropylene special material

[0128] The materials were weighed according to the following weight content:

[0129] Random copolymerized polypropylene resin 95wt%

[0130] Modified carbon nanotube 1wt%

[0131] Transparent nucleating agent 1wt%

[0132] Composite auxiliary agent 3wt% (antistatic agent 1wt%; acid scavenger 1wt%, primary antioxidant 0.5wt% and secondary antioxidant 0.5wt%).

[0133] The random copolymerized polypropylene resin is an ethylene-propylene copolymer resin with a melt index of 6g / 10min and an ethylene content of 2wt%; the transparent nucleating agent is NA-21, the antistatic agent is monoglyceride; the acid scavenger is calcium stearate; the primary antioxidant is 1010, the secondary antioxidant is 168; the outer diameter of the carbon nanotube is 20nm, the length is 10μm, the density is 2g / m 3 , and the surface area is 150m 2 / g.

[0134] The above materials were mixed in a low-speed mixer at 20°C for 3min, then melt-extruded in a twin-screw extruder, with the extrusion temperature being between 200-210°C and the screw rotation speed being 250rpm, and then the extruded material was cooled, air-dried and granulated to obtain the random copolymerized transparent polypropylene special material.

[0135] Experimental Example

[0136] The polypropylene special materials prepared in each example and comparative example were respectively tested for mechanical properties, transparency, etc., wherein the impact strength was tested according to GB / T1843-2008, the flexural modulus was tested according to GB / T9341-2008, the yellow index was tested according to GB / T 2409, and the haze was tested according to GB / T 2410; the specific test results are shown in the following table.

[0137] Table 4

[0138]

[0139]

[0140] From the data in the above table, it can be seen that the impact strength and flexural modulus of the random copolymer transparent polypropylene special material provided by the present application are significantly improved compared with the prior art, which indicates that the modified carbon nanotubes obtained by sequentially modifying the purified carbon nanotubes with a coupling agent, polydopamine and gelatin have good compatibility with the random copolymer polypropylene resin, effectively avoiding the agglomeration of the carbon nanotubes, so that the mechanical properties of the carbon nanotubes are fully exerted, and the carbon nanotubes can also play the role of physical crosslinking points, having the effects of reinforcement and toughening. The effects of examples 11-20 are more excellent than those of examples 1-10, because in examples 11-20, the modified carbon nanotubes are first mixed with part of the random copolymer polypropylene resin and the additives to form toughening master batches, and then the toughening master batches are mixed into the random copolymer polypropylene resin for secondary dispersion to further improve the dispersion uniformity of the carbon nanotubes.

[0141] Of course, the present application can have other various embodiments, and those skilled in the art can make various corresponding changes and modifications according to the present application without departing from the spirit and essence of the present application, but these corresponding changes and modifications shall all belong to the protection scope of the claims of the present application.

Claims

1. A special material for random copolymer transparent polypropylene, characterized in that, The components include the following contents: random copolymer polypropylene resin 95wt%-99.5wt%; modified carbon nanotubes 0.1wt%-1wt%; transparent nucleating agent 0.1wt%-1wt%; and composite additives 0.2wt%-3wt%. The modified carbon nanotubes are obtained by sequentially modifying the surface of carbon nanotubes purified by oxidation with coupling agent, polydopamine and gelatin.

2. A special material for random copolymer transparent polypropylene, characterized in that, The components include the following contents: random copolymer polypropylene resin 90wt%-99wt%, toughening masterbatch 1wt%-10wt%; The toughening masterbatch comprises the following components in the following proportions: random copolymer polypropylene resin 55wt%-96wt%; modified carbon nanotubes 0.5wt%-5wt%; transparent nucleating agent 0.5wt%-10wt%; and composite additives 3wt%-30wt%. The modified carbon nanotubes are obtained by sequentially modifying the surface of carbon nanotubes purified by oxidation with coupling agent, polydopamine and gelatin.

3. The random copolymer transparent polypropylene special material as described in claim 1 or 2, characterized in that, When purifying carbon nanotubes using an oxidation method, a mixed solution of potassium permanganate and concentrated sulfuric acid is used.

4. The random copolymer transparent polypropylene special material as described in claim 1 or 2, characterized in that, The composite additive is selected from at least one of antioxidants, antistatic agents, and deacidifying agents.

5. The random copolymer transparent polypropylene special material as described in claim 2, characterized in that, The toughening masterbatch comprises the following components in the following proportions: random copolymer polypropylene resin 55wt%-96wt%; modified carbon nanotubes 0.5wt%-5wt%; transparent nucleating agent 0.5wt%-10wt%; antistatic agent 1wt%-10wt%; acid remover 1wt%-10wt%; and antioxidant 1wt%-10wt%.

6. The random copolymer transparent polypropylene special material as described in claim 1, characterized in that, The random copolymer transparent polypropylene special material comprises the following components in the following proportions: random copolymer polypropylene resin 95wt%-99.5wt%; modified carbon nanotubes 0.1wt%-1wt%; transparent nucleating agent 0.1wt%-1wt%; antistatic agent 0.1wt%-0.5wt%; deacidifying agent 0.1wt%-0.5wt%; and antioxidant 0.1wt%-2wt%.

7. A method for preparing the random copolymer transparent polypropylene special material according to claim 1, characterized in that, Includes the following steps: Random copolymer polypropylene resin, modified carbon nanotubes, transparent nucleating agent and composite additives are mixed at room temperature and then melt-extruded in a twin-screw extruder to obtain the random copolymer transparent polypropylene special material.

8. A method for preparing the random copolymer transparent polypropylene special material according to claim 2, characterized in that, Includes the following steps: After mixing random copolymer polypropylene resin, modified carbon nanotubes, transparent nucleating agent and composite additives, the mixture is placed in a twin-screw extruder for melt extrusion to obtain toughening masterbatch. After mixing the random copolymer polypropylene resin and the toughening masterbatch, the mixture is placed in a twin-screw extruder for melt extrusion to obtain the random copolymer transparent polypropylene special material.

9. The method for preparing the random copolymer transparent polypropylene special material as described in claim 7 or 8, characterized in that, The preparation of the modified carbon nanotubes includes the following steps: Purification: Carbon nanotubes were dispersed in an oxidant and refluxed. After the reaction was completed, the nanotubes were separated, washed until neutral, and dried under vacuum to obtain purified carbon nanotubes. Coupling agent modification: The coupling agent and the purified carbon nanotubes are dispersed in ethanol and refluxed. After the reaction is completed, the ethanol is removed to obtain the coupling agent modified carbon nanotubes. Polydopamine modification: The carbon nanotubes modified with the coupling agent and polydopamine were reacted in Tris-buffered saline. After the reaction was completed, the mixture was washed until neutral to obtain carbon nanotubes modified with the coupling agent and polydopamine. Gelatin modification: The coupling agent and polydopamine-modified carbon nanotubes are dispersed in deionized water, and then mixed with gelatin aqueous solution to react. After the reaction is completed, the solid obtained by separation is washed with deionized water and dried to obtain the modified carbon nanotubes.

10. The method for preparing the random copolymer transparent polypropylene special material as described in claim 9, characterized in that, In the purification step, the mass-to-volume ratio of the carbon nanotubes to the oxidant is 25 mg:(1-10) mL; the oxidant is a mixed solution of potassium permanganate and concentrated sulfuric acid with a mass ratio of (1-2):(1-2); and / or In the purification step, the carbon nanotubes have an outer diameter of 20-30 nm, a length of 10-30 μm, and a density of 2-3 g / cm³. 3 Surface area greater than 110m² 2 / g; and / or In the coupling agent modification step, the mass ratio of the purified carbon nanotubes to the coupling agent is 5:(1-10); and / or In the polydopamine modification step, the mass ratio of the coupling agent-modified carbon nanotubes to polydopamine is 5:(1-10); the mass-to-volume ratio of the coupling agent-modified carbon nanotubes to the Tris-buffer is 5 mg:(1-10) mL; and / or In the gelatin modification step, the mass ratio of the coupling agent and the polydopamine-modified carbon nanotubes to the gelatin is 5:(1-10).

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