Polypropylene masterbatch for injection molding and method for preparing the same

Abstract

The application belongs to the technical field of high polymer materials, and particularly discloses a polypropylene master batch for injection molding and a preparation method thereof.The polypropylene master batch for injection molding comprises the following components: polypropylene, ultra-high molecular weight polyethylene, white oil, inorganic nano-rigid particles, a modifier, an antioxidant and a processing aid.The polypropylene master batch for injection molding uses ultra-high molecular weight polyethylene as a modifier of polypropylene and uses white oil as a disentangling agent of the ultra-high molecular weight polyethylene (UHMWPE), so that the flowability of a PP / UHMWPE synthetic material can be improved, and the introduction of nano-scale inorganic rigid particle enhancers and elastomer modifiers can effectively improve the strength, toughness, heat resistance, compactness and wear resistance of the polypropylene master batch for injection molding.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a polypropylene masterbatch for injection molding and its preparation method. Background Technology

[0002] Polypropylene (PP) is a polymer formed by the polymerization of propylene. Due to its advantages such as low density, high strength, corrosion resistance, and ease of molding, it is widely used in household appliances, packaging, electrical equipment, and automobiles, making it one of the most widely used plastics worldwide. However, PP suffers from drawbacks such as high molding shrinkage, poor toughness, unsatisfactory abrasion resistance, and poor thermomechanical properties, which limit its applications. Currently, blending, filling, and reinforcing PP composite modification can fully utilize the advantages of modified materials and is a relatively simple and economical approach. However, current polypropylene materials still suffer from brittleness and poor abrasion resistance, necessitating the search for a polypropylene material with superior performance. Summary of the Invention

[0003] In view of the problems of brittleness and poor wear resistance of polypropylene materials involved in the prior art, the present invention will provide a polypropylene masterbatch for injection molding and its preparation method.

[0004] To achieve the above objectives, the following technical solutions are specifically included:

[0005] A polypropylene masterbatch for injection molding comprises the following components: polypropylene, ultra-high molecular weight polyethylene, white oil, inorganic rigid nanoparticles, modifier, antioxidant, and processing aid;

[0006] The polypropylene is in the form of 60-80 parts by mass, and the ultra-high molecular weight polyethylene is in the form of 20-40 parts by mass.

[0007] Based on a total mass content of 100% for polypropylene and ultra-high molecular weight polyethylene, the white oil has a mass percentage of 10-20%, the inorganic nano-rigid particles have a mass percentage of 3-5%, the modifier has a mass percentage of 0.5-1.2%, the antioxidant has a mass percentage of 0.2-0.4%, and the processing aid has a mass percentage of 0.4-1%.

[0008] The modifier is at least one of polyoxyethylene alkylphenol ether and polyethylene glycol monooleate.

[0009] This invention uses ultra-high molecular weight polyethylene as a modifier for polypropylene and white oil as a detangling agent for ultra-high molecular weight polyethylene (UHMWPE), which can improve the flowability of PP / UHMWPE synthetic materials. At the same time, the introduction of nano-scale inorganic rigid particle reinforcing agents and elastomer modifiers can effectively improve the strength, toughness, heat resistance, density, wear resistance and other properties of polypropylene masterbatch for injection molding.

[0010] Modifiers improve dispersibility and antistatic properties, which is beneficial for the dispersion of inorganic rigid nanoparticles in the matrix, improves the compatibility between inorganic rigid nanoparticles and the matrix, and allows the toughening, reinforcing and wear-resistant properties of inorganic rigid nanoparticles to be fully utilized.

[0011] Polyoxyethylene alkylphenol ethers and polyethylene glycol monooleate are both elastomer modifiers. Using elastomers as modifiers (dispersants) to improve the toughness of polymers often affects the strength, stiffness, dimensional stability, and heat resistance of the polymers themselves. However, using rigid particles (inorganic) to toughen polymers can not only improve the toughness of the polymers, but also improve their strength, heat distortion temperature, and processing fluidity. This shows the composite benefits of both toughening and strengthening, ensuring the balance between the stiffness and toughness of the polymer material and improving the wear resistance of the composite material.

[0012] This invention introduces ultra-high molecular weight polyethylene (UHMWPE) to modify polypropylene (PP). Due to the aggregated crystalline structure and entangled molecular chains of UHMWPE, it has excellent impact resistance, self-lubrication, wear resistance, and tensile strength. By using UHMWPE to blend and modify PP, the shortcomings of poor impact resistance and wear resistance of PP are improved, resulting in a PP composite material with excellent comprehensive performance, thereby broadening the application range of PP.

[0013] In a preferred embodiment of the present invention, the polypropylene includes homopolymer polypropylene, random copolymer polypropylene, and block copolymer polypropylene. At 230°C and a load of 2.16 kg, the melt flow rate of the polypropylene is 1-60 g / 10 min, and the density is 0.89-0.91 g / cm³. 3 .

[0014] As a further preferred embodiment of the present invention, the homopolymer polypropylene has a melt flow rate of 15-20 g / 10 min at 230°C and 2.16 kg load.

[0015] As a further preferred embodiment of the present invention, the homopolymer polypropylene has a melt mass flow rate of 17 g / 10 min at 230°C and 2.16 kg load.

[0016] As a further preferred embodiment of the present invention, the melt mass flow rate of the random copolymer polypropylene at 230°C and 2.16 kg load is 10-13 g / 10 min.

[0017] As a further preferred embodiment of the present invention, the random copolymer polypropylene has a melt mass flow rate of 11.6 g / 10 min at 230°C and 2.16 kg load.

[0018] As a further preferred embodiment of the present invention, the melt mass flow rate of the block copolymer polypropylene at 230°C and 2.16 kg load is 28-32 g / 10 min.

[0019] As a further preferred embodiment of the present invention, the melt mass flow rate of the block copolymer polypropylene at 230°C and 2.16 kg load is 30 g / 10 min.

[0020] As a further preferred embodiment of the present invention, the mass ratio of homopolymer polypropylene, random copolymer polypropylene, and block copolymer polypropylene is homopolymer polypropylene: random copolymer polypropylene: block copolymer polypropylene = (2-4): (1-2): (4-6).

[0021] As a further preferred embodiment of the present invention, the mass ratio of homopolymer polypropylene, random copolymer polypropylene, and block copolymer polypropylene is homopolymer polypropylene: random copolymer polypropylene: block copolymer polypropylene = 3:2:5.

[0022] Based on monomer type, polypropylene can be divided into homopolymer polypropylene and copolymer polypropylene; based on the spatial position of methyl groups (-CH3) in the polypropylene molecule, polypropylene can be divided into isotactic, syndiotactic, and atactic types. The invention of this invention reveals that products made from isotactic, syndiotactic, and atactic polypropylene exhibit optimal performance, and the combination of raw materials with different melt flow rates can broaden the processing temperature range and reduce energy consumption.

[0023] In a preferred embodiment of the present invention, the ultra-high molecular weight polyethylene has a viscosity-average molecular weight greater than or equal to 6.0 × 10⁻⁶. 6 g / mol.

[0024] In a further preferred embodiment of the present invention, the ultra-high molecular weight polyethylene has a viscosity-average molecular weight of 6.0 × 10⁻⁶. 6 -10 7 g / mol.

[0025] In a further preferred embodiment of the present invention, the ultra-high molecular weight polyethylene has a viscosity-average molecular weight of 6.2 × 10⁻⁶. 6 g / mol.

[0026] Ultra-high molecular weight polyethylene (UHMWPE) is a linear polyethylene with a relative molecular weight of over 1.5 million. Its high molecular weight and long molecular chains give it excellent comprehensive properties, such as excellent impact resistance, low coefficient of friction, and good abrasion resistance. Blending PP and UHMWPE can improve the impact resistance (toughness) and abrasion resistance (hardness) of PP, resulting in a high-performance PP / UHMWPE blend. The UHMWPE of this invention has a viscosity-average molecular weight greater than 6.0 × 10⁻⁶. 6g / mol. As the molecular weight increases, the high viscosity of UHMWPE limits the phase separation between PP and UHMWPE. Therefore, the impact performance of the system improves more significantly with the increase of molecular weight.

[0027] In a preferred embodiment of the present invention, the white oil has a specific gravity of 0.82 and a viscosity index of 24-28.

[0028] PP and UHMWPE have poor compatibility, with high interfacial tension and weak adhesion. Therefore, although the addition of UHMWPE can improve the performance of PP, the effect is not significant. White oil is a liquid mixture of hydrocarbons, mainly composed of C16-C31 normal and isoalkanes. This invention uses white oil as a flow modifier and de-entanglement agent for UHMWPE in injection molding polypropylene masterbatch, as well as a compatibilizer for PP and UHMWPE.

[0029] Swelling UHMWPE in white oil significantly improves its flowability and detangling effect. Adding the swollen UHMWPE to PP results in a significant increase in the tensile and impact strength of the PP. Furthermore, white oil, being a small molecule with good lubricating properties, further enhances the lubrication of UHMWPE, reducing the coefficient of friction and exhibiting better wear resistance under friction.

[0030] In a preferred embodiment of the present invention, the inorganic nano-rigid particles include at least one of nano-talc, nano-kaolin, spherical nano-alumina, and nano-titanium dioxide.

[0031] The inorganic rigid nanoparticles are nanoscale particles with specific quantum size effects, surface effects and macroscopic quantum effects. They have low agglomeration, narrow particle size distribution, good dispersibility, high hardness and low impurities. They have wear resistance, hardening and other properties, and can effectively improve the strength, toughness, heat resistance, density and wear resistance of composite materials.

[0032] In a preferred embodiment of the present invention, the inorganic nano-rigid particles include nano-talc, nano-kaolin, spherical nano-alumina, and nano-titanium dioxide, wherein the mass ratio of nano-talc: nano-kaolin: spherical nano-alumina: nano-titanium dioxide is (0.5-5):(0.2-3):(0.1-2):1.

[0033] As a further preferred embodiment of the present invention, the mass ratio of the nano-talc powder, nano-kaolin, spherical nano-alumina and nano-titanium dioxide is nano-talc powder: nano-kaolin: spherical nano-alumina: nano-titanium dioxide = 1:1:1:1.

[0034] Each type of particle plays a different role in composite materials, which can improve the overall performance of composite materials.

[0035] In the polypropylene masterbatch for injection molding of the present invention, inorganic rigid particles are uniformly dispersed in the continuous phase of the matrix PP / UHMWPE, generating a stress concentration effect. The particles induce a large number of streaks, forcing the matrix around the particles to undergo plastic deformation, absorbing a large amount of impact energy, and generating toughness. At the same time, the presence of inorganic rigid particles can also passivate and terminate streaks, hindering the development of streaks, and thus also playing a toughening effect.

[0036] In a preferred embodiment of the present invention, the average particle size of the nano-talc powder is 10-100 nm.

[0037] Talc, as a filler, has a toughening and reinforcing effect, improving the flexural strength, flexural modulus, heat distortion temperature, and dimensional stability of injection molding polypropylene masterbatches. It also imparts thermal retardancy to the injection molding polypropylene masterbatches. Nano-sized talc acts as stress concentration points in composite materials. When subjected to external forces, cavitation occurs at the edges of the particles and polymer. This cavitation releases the polymer's constraint on plasticity, causing significant plastic deformation and resulting in a substantial improvement in impact toughness.

[0038] In a preferred embodiment of the present invention, the nano-kaolin has an average particle size of 50-90 nm and a specific surface area of ​​150-250 m². 2 / g, loose bulk density is 0.05-0.15g / cm³ 3 .

[0039] Nano-kaolin has a small particle size, a large specific surface area, and good dispersibility. Nano-kaolin has a nucleation effect on the crystallization process of PP, increasing the crystallization temperature, shortening the molding cycle, and reducing product warpage and deformation.

[0040] In a preferred embodiment of the present invention, the spherical nano-alumina has an average particle size of 40-80 nm and a specific surface area of ​​1-10 m². 2 / g, bulk density is 0.1-0.6g / cm³ 3 .

[0041] Nano-Al2O3 is an effective nucleating agent for composite materials, which helps to reduce the size of PP spherulites, increase the crystallization temperature of PP, and improve the tensile strength and yield strength of composite materials.

[0042] In a preferred embodiment of the present invention, the specific surface area of ​​the nano-titanium dioxide is 20-100 m². 2 The bulk density is 0.1-0.8 g / cm³. 3 .

[0043] Nano-titanium dioxide has a small particle size, large specific surface area, and high activity, resulting in a larger contact area with PP and stronger adhesion to the matrix. When the composite material is subjected to external impact, it can form a physical three-dimensional network that acts as a stress concentration mechanism, causing the PP around the particles to undergo large plastic deformation and crazing, thus absorbing the impact energy. Therefore, the addition of nano-titanium dioxide can significantly improve the impact resistance of the composite material.

[0044] In a preferred embodiment of the present invention, the antioxidant is at least one of antioxidant 1010, antioxidant 1076, antioxidant 168, and antioxidant 626.

[0045] As a further preferred embodiment of the present invention, the antioxidant is antioxidant B215, which is a mixture of antioxidants 1010 and 168 in a mass ratio of 2:1.

[0046] In a preferred embodiment of the present invention, the processing aid includes at least one of solid paraffin, polyethylene wax, and aliphatic polyester.

[0047] Processing aids can reduce the friction between the melt and the screw during extrusion, thereby improving the surface quality of injection molded products.

[0048] This invention also provides a method for preparing polypropylene masterbatch for injection molding, comprising the following steps:

[0049] (1) Ultra-high molecular weight polyethylene and white oil are heated under stirring to carry out a dewinding reaction, thereby obtaining dewinding ultra-high molecular weight polyethylene;

[0050] (2) Polypropylene, the unwound ultra-high molecular weight polyethylene, inorganic nano-rigid particles, modifier, antioxidant and processing aid are mixed, and then extruded and granulated after kneading and melting to obtain the polypropylene masterbatch for injection molding.

[0051] In a preferred embodiment of the present invention, in step (1), the stirring speed is 100-500 r / min.

[0052] As a further preferred embodiment of the present invention, in step (1), the stirring speed is 300 r / min.

[0053] In a preferred embodiment of the present invention, in step (1), the temperature of the unwinding reaction is 120-160°C and the time of the unwinding reaction is 2-60 min.

[0054] As a further preferred embodiment of the present invention, in step (1), the temperature of the unwinding reaction is 140°C and the time of the unwinding reaction is 10 min.

[0055] In a preferred embodiment of the present invention, the mixing process parameters in step (2) are: rotation speed of 1200-1800 r / min and time of 5-8 min.

[0056] In a preferred embodiment of the present invention, in step (2), the extrusion device is a four-screw extruder, wherein the screw length-to-diameter ratio is 35:1, the main engine speed is 300-400 r / min, the vacuum degree is -0.06 MPa, and the highest section temperature is 220-240℃.

[0057] In a preferred embodiment of the present invention, in step (2), the inorganic nano-rigid particles are further subjected to a drying pretreatment at 60-120°C for 2-24 hours.

[0058] Compared with the prior art, the present invention has the following beneficial effects:

[0059] (1) Ultra-high molecular weight polyethylene has excellent impact resistance and wear resistance because UHMWPE crystals aggregate and molecular chains are interconnected to form a complex network continuous structure, which can improve the toughness of PP and the strength does not decrease significantly.

[0060] (2) PP has poor molecular chain symmetry due to the presence of -CH3 in its side chain, making it prone to wear. This invention further improves wear resistance by adding inorganic nano-rigid particles. Introducing an appropriate amount of rigid particles into the blend system can effectively improve the overall performance of the system and solve the problem of simultaneously improving the strength and toughness of the material. The rigid particles are treated with a modifier (dispersant) to increase their dispersion in the matrix, thereby improving the performance of the composite material.

[0061] (3) Due to the high entanglement of UHMWPE molecular chains, UHMWPE has a high melt viscosity. The huge viscosity mismatch between UHMWPE and the blend components inhibits the hybrid dynamics of the polymer melt, resulting in poor blending effect. Therefore, white oil is introduced to pretreat UHMWPE to de-entangle it. At the same time, white oil can also promote the dispersion of UHMWPE in PP, improve the flowability of the blend, and enhance the impact performance and wear resistance of the blend.

[0062] (4) When the extruder is used for processing, the UHMWPE is not well dispersed in PP, which will lead to a decrease in the strength and toughness of the blended material. However, the four-screw extruder used in this invention will disperse the material more evenly than the conventional twin-screw extruder, and the blended material can achieve the effect of simultaneous strengthening and toughening. Detailed Implementation

[0063] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below through specific embodiments.

[0064] Unless otherwise specified, the experimental methods used in the examples and comparative examples are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0065] At 230℃ and 2.16Kg load, homopolymer polypropylene HP500P with a melt flow rate of 17g / 10min was purchased from Daqing Petrochemical Company of China National Petroleum Corporation; random copolymer polypropylene SP-179 with a melt flow rate of 11.6g / 10min was purchased from North China Huajin Chemical Industry Co., Ltd.; and block copolymer polypropylene K7726H-RC with a melt flow rate of 30g / 10min was purchased from North China Huajin Chemical Industry Co., Ltd.

[0066] The ultra-high molecular weight polyethylene (UHMWPE) used in the examples all had a viscosity-average molecular weight of 6.2 × 10⁻⁶. 6 g / mol, extrusion and injection molding grade, product code UPE 2801, purchased from Shanghai Chuhao Import & Export Co., Ltd.

[0067] The white oil is industrial grade white oil 32#, with a specific gravity of 0.82 and a viscosity index of 24-28, purchased from Guangzhou Tongjie Chemical Co., Ltd.

[0068] Nano-talc powder, 100nm particle size, purchased from Shijiazhuang Zhengyu New Material Technology Co., Ltd.; Nano-grade kaolin, 80nm particle size, specific surface area 200m². 2 / g, loose bulk density 0.1g / cm³ 3 Product model TG-Y-3, purchased from Guangzhou Changyu Chemical Co., Ltd.; spherical alumina (Al2O3) nanoparticles, particle size 60nm, specific surface area 8m². 2 / g, bulk density 0.3g / cm³ 3 Product model TAP-A21, purchased from Jiangsu Tianxing New Materials Co., Ltd.; nano titanium dioxide, specific surface area 60m². 2 / g, bulk density 0.4g / cm³ 3 The product model is TTP-A12, purchased from Jiangsu Tianxing New Materials Co., Ltd.

[0069] Polyoxyethylene alkylphenol ether, colorless to pale yellow oil, product model NP-7, purchased from Haian Petrochemical Plant, Jiangsu Province; polyethylene glycol monooleate, amber liquid, product model PEG400MO, purchased from Shanghai Huijun Chemical Co., Ltd.

[0070] Antioxidant B215 is a mixture of antioxidants 1010 and 168 in a mass ratio of 2:1.

[0071] Unless otherwise specified, the same type of product was used for the same substance in the following examples and comparative examples.

[0072] Example 1

[0073] A polypropylene masterbatch for injection molding comprises the following components in parts by weight: 70 parts of PP resin obtained by mixing homopolymer polypropylene HP500P, random copolymer polypropylene SP-179 and block copolymer polypropylene K7726H-RC in a mass ratio of 3:2:5; 30 parts of ultra-high molecular weight polyethylene UHMWPE; 15 parts of white oil; 4 parts of inorganic nano-rigid particles compounded with nano-talc, nano-kaolin, spherical nano-alumina and nano-titanium dioxide in a mass ratio of 1:1:1:1; 0.8 parts of polyoxyethylene alkylphenol ether modifier (dispersant); 0.3 parts of antioxidant B215; and 0.7 parts of solid paraffin wax processing aid.

[0074] The method for preparing polypropylene masterbatch for injection molding in this embodiment includes the following steps:

[0075] (1) Weigh out ultra-high molecular weight polyethylene (UHMWPE) according to the mass ratio and put it into a flask. Add an appropriate amount of white oil, heat the oil bath to 140°C, and stir for 10 minutes at a speed of 300 r / min to obtain unwound ultra-high molecular weight polyethylene (UHMWPE).

[0076] (2) The rigid particle nano talc powder, nano kaolin, spherical nano alumina (Al2O3) and nano titanium dioxide were placed in an oven at 110°C and dried for 10 hours, and then put into use.

[0077] (3) Weigh out PP resin, unwound ultra-high molecular weight polyethylene (UHMWPE) mentioned in step (1), inorganic nano-rigid particles, modifier (dispersant), antioxidant and processing aid according to the mass ratio, and then put each raw material component into a high-speed mixer for dry mixing.

[0078] (4) The product obtained by mixing in step (3) is placed in a four-screw extruder and then extruded and granulated after mixing and melting to obtain the polypropylene masterbatch for injection molding.

[0079] The process parameters of the mixing machine are as follows: rotation speed of 1500 r / min and time of 6 min; the four-screw extruder is a co-rotating four-screw extruder with a screw length-to-diameter ratio of 35:1, a main machine rotation speed of 350 r / min, a vacuum degree of -0.06 MPa, and a maximum section temperature of 230℃.

[0080] Example 2

[0081] A polypropylene masterbatch for injection molding comprises the following components in parts by weight: 75 parts of PP resin obtained by mixing homopolymer polypropylene HP500P, random copolymer polypropylene SP-179 and block copolymer polypropylene K7726H-RC in a mass ratio of 3:2:5; 25 parts of ultra-high molecular weight polyethylene UHMWPE; 12.5 parts of white oil; 4 parts of inorganic nano-rigid particles compounded with nano-talc, nano-kaolin, spherical nano-alumina and nano-titanium dioxide in a mass ratio of 1:1:1:1; 0.8 parts of polyethylene glycol monooleate as a modifier (dispersant); 0.3 parts of antioxidant B215; and 0.7 parts of solid paraffin as a processing aid.

[0082] The method for preparing polypropylene masterbatch for injection molding in this embodiment includes the following steps:

[0083] (1) Weigh out ultra-high molecular weight polyethylene (UHMWPE) according to the mass ratio and put it into a flask. Add an appropriate amount of white oil, heat the oil bath to 140°C, and stir for 10 minutes at a speed of 300 r / min to obtain unwound ultra-high molecular weight polyethylene (UHMWPE) for later use.

[0084] (2) The rigid particle nano talc powder, nano kaolin, spherical nano alumina (Al2O3) and nano titanium dioxide were placed in an oven at 110°C and dried for 10 hours, and then put into use.

[0085] (3) Weigh out PP resin, unwound ultra-high molecular weight polyethylene (UHMWPE) mentioned in step (1), inorganic nano-rigid particles, modifier (dispersant), antioxidant and processing aid according to the mass ratio, and then put each raw material component into a high-speed mixer for dry mixing.

[0086] (4) The product obtained by mixing in step (3) is placed in a four-screw extruder and then extruded and granulated after mixing and melting to obtain the polypropylene masterbatch for injection molding.

[0087] The process parameters of the mixing machine are as follows: rotation speed of 1650 r / min and time of 6 min; the four-screw extruder is a co-rotating four-screw extruder with a screw length-to-diameter ratio of 35:1, a main machine rotation speed of 375 r / min, a vacuum degree of -0.06 MPa, and a maximum section temperature of 235℃.

[0088] Example 3

[0089] A polypropylene masterbatch for injection molding comprises the following components in parts by weight: 80 parts of PP resin obtained by mixing homopolymer polypropylene HP500P, random copolymer polypropylene SP-179 and block copolymer polypropylene K7726H-RC in a mass ratio of 3:2:5; 20 parts of ultra-high molecular weight polyethylene UHMWPE; 10 parts of white oil; 4 parts of inorganic nano-rigid particles compounded with nano-talc, nano-kaolin, spherical nano-alumina and nano-titanium dioxide in a mass ratio of 1:1:1:1; 0.8 parts of polyoxyethylene alkylphenol ether modifier (dispersant); 0.3 parts of antioxidant B215; and 0.7 parts of solid paraffin wax processing aid.

[0090] The method for preparing polypropylene masterbatch for injection molding in this embodiment includes the following steps:

[0091] (1) Weigh out ultra-high molecular weight polyethylene (UHMWPE) according to the mass ratio and put it into a flask. Add an appropriate amount of white oil, heat the oil bath to 140°C, and stir for 10 minutes at a speed of 300 r / min to obtain unwound ultra-high molecular weight polyethylene (UHMWPE) for later use.

[0092] (2) The rigid particle nano talc powder, nano kaolin, spherical nano alumina (Al2O3) and nano titanium dioxide were placed in an oven at 110°C and dried for 10 hours, and then put into use.

[0093] (3) Weigh out PP resin, unwound ultra-high molecular weight polyethylene (UHMWPE) mentioned in step (1), inorganic nano-rigid particles, modifier (dispersant), antioxidant and processing aid according to the mass ratio, and then put each raw material component into a high-speed mixer for dry mixing.

[0094] (4) The product obtained by mixing in step (3) is placed in a four-screw extruder and then extruded and granulated after mixing and melting to obtain the polypropylene masterbatch for injection molding.

[0095] The process parameters of the mixing machine are as follows: rotation speed of 1500 r / min and time of 6 min; the four-screw extruder is a co-rotating four-screw extruder with a screw length-to-diameter ratio of 35:1, a main machine rotation speed of 350 r / min, a vacuum degree of -0.06 MPa, and a maximum section temperature of 230℃.

[0096] Example 4

[0097] A polypropylene masterbatch for injection molding comprises the following components in parts by weight: 75 parts of PP resin obtained by mixing homopolymer polypropylene HP500P, random copolymer polypropylene SP-179 and block copolymer polypropylene K7726H-RC in a mass ratio of 3:2:5; 25 parts of ultra-high molecular weight polyethylene UHMWPE; 12.5 parts of white oil; 4 parts of inorganic nano-rigid particles compounded with nano-talc, nano-kaolin, spherical nano-alumina and nano-titanium dioxide in a mass ratio of 1:1:1:1; 0.8 parts of polyoxyethylene alkylphenol ether modifier (dispersant); 0.3 parts of antioxidant B215; and 0.7 parts of solid paraffin wax processing aid.

[0098] The method for preparing polypropylene masterbatch for injection molding in this embodiment includes the following steps:

[0099] (1) Weigh out ultra-high molecular weight polyethylene (UHMWPE) according to the mass ratio and put it into a flask. Add an appropriate amount of white oil, heat the oil bath to 140°C, and stir for 10 minutes at a speed of 300 r / min to obtain unwound ultra-high molecular weight polyethylene (UHMWPE) for later use.

[0100] (2) The rigid particle nano talc powder, nano kaolin, spherical nano alumina (Al2O3) and nano titanium dioxide were placed in an oven at 110°C and dried for 10 hours, and then put into use.

[0101] (3) Weigh out PP resin, unwound ultra-high molecular weight polyethylene (UHMWPE) mentioned in step (1), inorganic nano-rigid particles, modifier (dispersant), antioxidant and processing aid according to the mass ratio, and then put each raw material component into a high-speed mixer for dry mixing.

[0102] (4) The product obtained by mixing in step (3) is placed in a four-screw extruder and then extruded and granulated after mixing and melting to obtain the polypropylene masterbatch for injection molding.

[0103] The process parameters of the mixing machine are as follows: rotation speed of 1650 r / min and time of 6 min; the four-screw extruder is a co-rotating four-screw extruder with a screw length-to-diameter ratio of 35:1, a main machine rotation speed of 375 r / min, a vacuum degree of -0.06 MPa, and a maximum section temperature of 235℃.

[0104] Example 5

[0105] A polypropylene masterbatch for injection molding comprises the following components in parts by weight: 60 parts of PP resin obtained by mixing homopolymer polypropylene HP500P, random copolymer polypropylene SP-179 and block copolymer polypropylene K7726H-RC in a mass ratio of 3:2:5; 40 parts of ultra-high molecular weight polyethylene UHMWPE; 20 parts of white oil; 4 parts of inorganic nano-rigid particles compounded with nano-talc, nano-kaolin, spherical nano-alumina and nano-titanium dioxide in a mass ratio of 1:1:1:1; 0.8 parts of polyoxyethylene alkylphenol ether modifier (dispersant); 0.3 parts of antioxidant B215; and 0.7 parts of solid paraffin wax processing aid.

[0106] The method for preparing polypropylene masterbatch for injection molding in this embodiment includes the following steps:

[0107] (1) Weigh out ultra-high molecular weight polyethylene (UHMWPE) according to the mass ratio and put it into a flask. Add an appropriate amount of white oil, heat the oil bath to 140°C, and stir for 10 minutes at a speed of 300 r / min to obtain unwound ultra-high molecular weight polyethylene (UHMWPE) for later use.

[0108] (2) The rigid particle nano talc powder, nano kaolin, spherical nano alumina (Al2O3) and nano titanium dioxide were placed in an oven at 110°C and dried for 10 hours, and then put into use.

[0109] (3) Weigh out PP resin, unwound ultra-high molecular weight polyethylene (UHMWPE) mentioned in step (1), inorganic nano-rigid particles, modifier (dispersant), antioxidant and processing aid according to the mass ratio, and then put each raw material component into a high-speed mixer for dry mixing.

[0110] (4) The product obtained by mixing in step (3) is placed in a four-screw extruder and then extruded and granulated after mixing and melting to obtain the polypropylene masterbatch for injection molding.

[0111] The process parameters of the mixing machine are as follows: rotation speed of 1500 r / min and time of 6 min; the four-screw extruder is a co-rotating four-screw extruder with a screw length-to-diameter ratio of 35:1, a main machine rotation speed of 350 r / min, a vacuum degree of -0.06 MPa, and a maximum section temperature of 230℃.

[0112] Examples 6-9 below are basically the same as Example 1, except that the amounts of inorganic nano-rigid particles, modifiers, antioxidants and processing aids are different.

[0113] Example 6

[0114] Compared with Example 1, the difference in this embodiment lies in the following weight parts: 3 parts of inorganic nano-rigid particles compounded with nano-talc powder, nano-kaolin, spherical nano-alumina and nano-titanium dioxide in a mass ratio of 1:1:1:1; 1.0 part of modifier (dispersant) polyoxyethylene alkylphenol ether; 0.2 parts of antioxidant B215; 1.0 part of processing aid solid paraffin; and the rest are the same.

[0115] Example 7

[0116] Compared with Example 1, the difference in this embodiment lies in the following weight parts: 5 parts of inorganic nano-rigid particles compounded with nano-talc powder, nano-kaolin, spherical nano-alumina and nano-titanium dioxide in a mass ratio of 1:1:1:1; 0.65 parts of modifier (dispersant) polyoxyethylene alkylphenol ether; 0.2 parts of antioxidant B215; 0.85 parts of processing aid solid paraffin; and the rest are the same.

[0117] Example 8

[0118] The difference between this embodiment and Example 1 lies in the following weight proportions: 3 parts of inorganic nano-rigid particles compounded with nano-talc, nano-kaolin, spherical nano-alumina and nano-titanium dioxide in a mass ratio of 1:1:1:1; 1.2 parts of polyoxyethylene alkylphenol ether modifier (dispersant); 0.4 parts of antioxidant B215; 0.55 parts of solid paraffin wax processing aid; and the rest are the same.

[0119] Example 9

[0120] Compared with Example 1, the difference in this embodiment lies in the following weight proportions of components: 5 parts of inorganic nano-rigid particles compounded with nano-talc powder, nano-kaolin, spherical nano-alumina and nano-titanium dioxide in a mass ratio of 1:1:1:1; 0.5 parts of modifier (dispersant) polyoxyethylene alkylphenol ether; 0.4 parts of antioxidant B215; 0.4 parts of processing aid solid paraffin; and the rest are the same.

[0121] Examples 10-13 are basically the same as Example 1, except that the inorganic nano-rigid particles are a single component.

[0122] Example 10

[0123] The difference between this embodiment and embodiment 1 is that the inorganic nano-rigid particles in this embodiment are 4 parts of nano-talc powder.

[0124] Example 11

[0125] The difference between this embodiment and embodiment 1 is that the inorganic nano-rigid particles in this embodiment are 4 parts of nano-kaolin.

[0126] Example 12

[0127] The difference between this embodiment and embodiment 1 is that the inorganic nano-rigid particles in this embodiment are 4 parts of nano-alumina.

[0128] Example 13

[0129] The difference between this embodiment and embodiment 1 is that the inorganic nano-rigid particles in this embodiment are 4 parts of nano-titanium dioxide.

[0130] Comparative Examples 1-3 are basically the same as Example 1, except that only a single polypropylene raw material is used.

[0131] Comparative Example 1

[0132] The difference between this comparative example and Example 1 is that the PP resin in this comparative example is 70 parts of homopolymer polypropylene HP500P.

[0133] Comparative Example 2

[0134] The difference between this comparative example and Example 1 is that the PP resin in this comparative example is random copolymer polypropylene SP-17970 parts.

[0135] Comparative Example 3

[0136] The difference between this comparative example and Example 1 is that the PP resin in this comparative example is 70 parts of block copolymer polypropylene K7726H-RC.

[0137] Comparative Example 4

[0138] This comparative example is basically the same as Example 1, except that the ultra-high molecular weight polyethylene (UHMWPE) in this comparative example has a relatively small molecular weight, with a viscosity-average molecular weight of 3.0 × 10⁻⁶. 6 g / mol, purchased from Shanghai Lianle Chemical Technology Co., Ltd.

[0139] Comparative Example 5

[0140] This comparative example is basically the same as Example 1, except that the ultra-high molecular weight polyethylene (UHMWPE) in this comparative example has not been treated with white oil, that is, there is no step (1) process and no white oil is added.

[0141] Comparative Example 6

[0142] This comparative example is basically the same as Example 1, except that the polypropylene masterbatch used for injection molding in this comparative example does not contain inorganic nano-rigid particles.

[0143] Comparative Example 7

[0144] This comparative example is basically the same as Example 1, except that the polypropylene masterbatch used for injection molding in this comparative example does not contain a modifier.

[0145] Comparative Example 8

[0146] This comparative example is basically the same as Example 1, except that the modifier in this comparative example is an alkylaryl phosphate.

[0147] Performance testing

[0148] The properties of the polypropylene masterbatch for injection molding obtained in the above embodiments and comparative examples were characterized. The specific test items and test methods are as follows, and the test results are shown in Table 1.

[0149] Tensile strength: Tested according to GB / T1040-2006 standard, where the tensile rate is 50 mm / min and the tensile temperature is 25℃.

[0150] Bending strength: Tested according to GB / T9341-2008 standard, with specific test conditions as follows: sample size 80×10×4mm, pressing speed 2mm / min.

[0151] Flexural modulus: Tested according to GB / T9341-2008 standard, with specific test conditions as follows: sample size 80×10×4mm, pressing speed 2mm / min.

[0152] Notched impact strength of simply supported beam: Tested according to GB / T1043-2008 standard. The specific test conditions are as follows: a cuboid spline with a specification of 80×10×4mm and a V-shaped notch (0.8mm deep) is selected as the characterization sample, and the pendulum energy is 25J.

[0153] Scratch resistance was tested according to PV3592 with a load of 10N. The scratch resistance was evaluated by measuring the ΔL on the material surface. The smaller the value of ΔL, the better the scratch resistance of the material.

[0154] Rockwell hardness: Tested according to GB / T3398-2008 standard, with specific test conditions of using an indenter with a diameter of 12.7 mm and a main load of 588.4 N.

[0155] Heat distortion temperature: Tested according to GB / T1634-2019 standard, with specific test conditions as follows: sample size 80×10×4mm, applied bending stress 0.45MPa (Method B).

[0156] Table 1. Test results of polypropylene masterbatch for injection molding obtained from the examples and comparative examples.

[0157]

[0158]

[0159] As can be seen from Examples 1, 3 and 5, the ratio of PP resin to ultra-high molecular weight polyethylene significantly affects the rigidity, toughness and wear resistance of polypropylene masterbatch for injection molding.

[0160] As can be seen from Example 1 and Comparative Examples 1-3, the polypropylene masterbatch for injection molding prepared by using three types of polypropylene resins simultaneously—homogeneous polypropylene, random copolymer polypropylene, and block copolymer polypropylene—has better rigidity, toughness, and wear resistance than that prepared by using only one of them.

[0161] As can be seen from Examples 2 and 4, Example 1 and Comparative Example 8, the type of modifier significantly affects the rigidity, toughness and wear resistance of polypropylene masterbatch for injection molding.

[0162] As can be seen from Example 1 and Comparative Example 4, the viscosity-average molecular weight of the ultra-high molecular weight polyethylene used is greater than 6.0 × 10⁻⁶. 6 Polypropylene masterbatch for injection molding exhibits superior rigidity, toughness, and abrasion resistance at g / mol.

[0163] As can be seen from Examples 6-9, the masterbatch prepared by appropriately adjusting the amounts of inorganic nano-rigid particles, modifiers, antioxidants, and processing aids can also meet the required performance.

[0164] As can be seen from Example 1 and Comparative Examples 6 and 7, the masterbatch prepared without the addition of inorganic nano-rigid particles and modifiers has poorer overall performance.

[0165] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A polypropylene masterbatch for injection molding, characterized in that, It includes the following components: polypropylene, ultra-high molecular weight polyethylene, white oil, inorganic nano-rigid particles, modifiers, antioxidants, and processing aids; The polypropylene is in the form of 60-80 parts by mass, and the ultra-high molecular weight polyethylene is in the form of 20-40 parts by mass. Based on a total mass content of 100% polypropylene and ultra-high molecular weight polyethylene, the white oil has a mass percentage of 10-20%, the inorganic nano-rigid particles have a mass percentage of 3-5%, the modifier has a mass percentage of 0.5-1.2%, the antioxidant has a mass percentage of 0.2-0.4%, and the processing aid has a mass percentage of 0.4-1%. The modifier is at least one of polyoxyethylene alkylphenol ether and polyethylene glycol monooleate; The polypropylene includes homopolymer polypropylene, random copolymer polypropylene, and block copolymer polypropylene; The ultra-high molecular weight polyethylene has a viscosity-average molecular weight greater than or equal to 6.0 × 10⁻⁶. 6 g / mol; White oil was used as an untangling agent for ultra-high molecular weight polyethylene.

2. The polypropylene masterbatch for injection molding as described in claim 1, characterized in that, At 230℃ and a load of 2.16 kg, the melt flow rate of polypropylene is 1-60 g / 10 min, and the density is 0.89-0.91 g / cm³. 3 .

3. The polypropylene masterbatch for injection molding as described in claim 2, characterized in that, The mass ratio of homopolymer polypropylene, random copolymer polypropylene, and block copolymer polypropylene is homopolymer polypropylene: random copolymer polypropylene: block copolymer polypropylene = (2-4): (1-2): (4-6).

4. The polypropylene masterbatch for injection molding as described in claim 1, characterized in that, The inorganic nano-rigid particles include at least one of nano-talc, nano-kaolin, spherical nano-alumina, and nano-titanium dioxide.

5. The polypropylene masterbatch for injection molding as described in claim 4, characterized in that, The mass ratio of the nano-talc powder, nano-kaolin, spherical nano-alumina, and nano-titanium dioxide is nano-talc powder: nano-kaolin: spherical nano-alumina: nano-titanium dioxide = (0.5-5): (0.2-3): (0.1-2):

1.

6. The polypropylene masterbatch for injection molding as described in claim 4, characterized in that, The nano-talc powder has an average particle size of 10-100 nm; the nano-kaolin has an average particle size of 50-90 nm and a specific surface area of ​​150-250 m². 2 / g, loose bulk density is 0.05-0.15g / cm³ 3 The spherical nano-alumina has an average particle size of 40-80 nm and a specific surface area of ​​1-10 m². 2 / g, bulk density is 0.1-0.6g / cm³ 3 The specific surface area of ​​the nano-titanium dioxide is 20-100 m². 2 / g, bulk density is 0.1-0.8g / cm³ 3 .

7. The polypropylene masterbatch for injection molding as described in claim 1, characterized in that, The white oil has a specific gravity of 0.82 and a viscosity index of 24-28; the antioxidant includes at least one of antioxidant 1010, antioxidant 1076, antioxidant 168, and antioxidant 626; the processing aid includes at least one of solid paraffin wax, polyethylene wax, and aliphatic polyester.

8. A method for preparing polypropylene masterbatch for injection molding according to any one of claims 1-7, characterized in that, Includes the following steps: (1) Ultra-high molecular weight polyethylene and white oil are heated under stirring to carry out a dewinding reaction to obtain dewinded ultra-high molecular weight polyethylene; (2) The polypropylene, the unwinding ultra-high molecular weight polyethylene, inorganic nano-rigid particles, modifier, antioxidant and processing aid are mixed, and then extruded and granulated after kneading and melting to obtain the polypropylene masterbatch for injection molding.

9. The method for preparing polypropylene masterbatch for injection molding as described in claim 8, characterized in that, In step (1), the stirring speed is 100-500 r / min; in step (1), the temperature of the unwinding reaction is 120-160℃, and the time of the unwinding reaction is 2-60 min; in step (2), the mixing process parameters are: the speed is 1200-1800 r / min, and the time is 5-8 min; in step (2), the extrusion device is a four-screw extruder, wherein the screw length-to-diameter ratio is 35:1, the main machine speed is 300-400 r / min, the vacuum degree is -0.06 MPa, and the highest section temperature is 220-240℃.

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