High-melt-strength low-shrinkage polypropylene material and preparation method thereof

Abstract

The invention discloses a polypropylene material with high melt strength and low shrinkage rate and a preparation method thereof, and the polypropylene material comprises the following components in percentage by weight: polypropylene, a grafting monomer, a polar monomer, an organic peroxide initiator, a nucleating agent, an antioxidant and a slipping agent, the grafting monomer is prepared from a polyol acrylate compound and an amino sugar alcohol compound. The polypropylene material disclosed by the invention has the performance characteristics of high melt strength and low shrinkage rate, can have better molding and sag-resistant effects in the material processing process, and can be applied to the molding processing fields of blister, blow molding, foaming and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of processing and preparation of polymer materials, and particularly relates to a high melt strength and low shrinkage polypropylene material and a preparation method thereof. Background Art

[0002] Polypropylene materials have the characteristics of good mechanical properties, optical properties, processing properties, non-toxicity and low price, and are widely used in industries such as blow molding, foaming, thermoforming by vacuum forming, etc. Their products involve fields such as food packaging, medical materials, electronic appliances, industrial pallets, etc. With the continuous upgrading of market demand, the demand of production enterprises for polypropylene materials with high melt strength and low shrinkage rate is becoming increasingly urgent.

[0003] At present in the market, most product manufacturers adopt the method of blending modification, and carry out melt blending by adding components such as polyethylene, POE, glass fiber, talcum powder, nano materials, etc. to polypropylene to improve the rigidity of the material and achieve the effects of melt dripping resistance and low shrinkage rate. However, due to the difference in resin compatibility, this method has problems such as uneven mixing, reduced mechanical properties, surface ripple flow marks on products, and large fluctuations in product quality. Some manufacturers prepare branched modified polypropylene by reactive extrusion, but the degree of branching of this method is relatively low, and it is difficult to effectively improve the melt strength of polypropylene materials. In addition, the complex process of in-situ polymerization for preparing high melt strength polypropylene and the high price of functional additives also limit the production of its special materials.

[0004] Chinese Patent CN 112625363 B discloses a modified polypropylene material for low-VOC, low-gloss and low-shrinkage automotive interiors and a preparation method thereof, which adopts adding POE and talcum powder to polypropylene for melt blending to reduce the shrinkage rate of the material. However, talcum powder is used in this material, and talcum powder has problems such as easy agglomeration and uneven dispersion, and the melt strength performance is not reflected.

[0005] Chinese Patent CN 114276620 A discloses a low shrinkage rate polypropylene composite material, a preparation method and an application thereof, which carry out melt blending of polypropylene with polyolefin elastomer and talcum powder. However, talcum powder is used in this material, and talcum powder has problems such as easy agglomeration and uneven dispersion, and the melt strength performance is not reflected.

[0006] Chinese Patent CN 111073136 A discloses a low shrinkage polypropylene composition and a preparation method thereof, which obtain a low shrinkage polypropylene composition by combining a specific nucleating agent, inorganic nanoparticles, petroleum resin with polypropylene, etc. This polypropylene composition reduces the shrinkage rate of the polypropylene material by adding a nucleating agent, and the degree of anisotropy of shrinkage is reduced. However, the added inorganic nanoparticles have problems such as poor compatibility and uneven dispersion, and the melt strength performance is not reflected.

[0007] Chinese Patent CN 112708234 A discloses a modified polypropylene material, its preparation method and applications. By blending reinforcing fibers such as glass fiber, quartz fiber, basalt fiber, etc. in the polypropylene material, the mechanical properties and melt strength of the polypropylene material are improved. However, the compatibility between the reinforcing fiber and the matrix resin is poor, resulting in a decrease in the toughness and impact resistance of the material. In addition, there are also problems such as surface floating fibers and difficulty in recycling.

[0008] Chinese Patent CN 112724510 A discloses a reinforced polypropylene material, its preparation method and applications. By melt blending linear polypropylene, long-chain branched polypropylene, reinforcing fiber, and fluorine compounds, high melt strength polypropylene is prepared. There are problems with poor compatibility between the reinforcing fiber and the fluoride, and the melt strength performance is not demonstrated.

[0009] Chinese Patent CN 112724508 A discloses a high melt strength polypropylene material, its preparation method and applications. By melt blending linear polypropylene, long-chain branched polypropylene, and fluorine compounds, a branched structure with entangled molecular chains is formed to improve the melt strength of the polypropylene material. The fluorine compounds used in this preparation method have a large difference in melting temperature from the polypropylene material, and there is a problem of uneven dispersion during blending.

[0010] Chinese Patent CN 107417859 B discloses a high melt strength polypropylene grafted with heteroaromatic derivatives and its preparation method. By reacting polypropylene with a heteroaromatic graft monomer under the action of a peroxide initiator through reactive extrusion, high melt strength long-chain branched polypropylene is prepared. However, the shrinkage rate performance of this polypropylene is not demonstrated.

[0011] Chinese Patent CN 109438602 B discloses a special polypropylene resin for high melt strength thermoforming and its preparation method. Using a catalyst with a wide molecular weight distribution, adding a comonomer ethylene on a single-loop tubular polypropylene device in the Spheripol process, an atactic copolymer polypropylene base resin with a relatively wide molecular weight distribution is produced, and then a high melt strength polypropylene resin is obtained by adding a highly efficient nucleating agent and extrusion granulation. The in-situ polymerization process is relatively complex, with high requirements for the performance of the catalyst, and the shrinkage rate performance of this polypropylene resin is not demonstrated.

[0012] Chinese Patent CN 112280167 A discloses a preparation method of a homopolypropylene resin with a wide molecular weight distribution, heat resistance, high rigidity, transparency, and low shrinkage. Based on the wide molecular weight distribution homopolypropylene resin produced in a polypropylene device using the Spheripol process, a highly efficient nucleating agent system is added to prepare a homopolypropylene with high rigidity and low shrinkage. However, the melt strength performance of this homopolypropylene resin is not demonstrated.

[0013] Chinese Patent CN105859920A discloses a highly grafted functionalized ethylene propylene diene monomer (EPDM) and its preparation method. The multi-functional graft monomer is prepared by the following steps: dissolving pentaerythritol mercaptopropionate in an organic solvent to form a first solution; dissolving an unsaturated carboxylic acid or acid anhydride in an organic solvent, and adding a radical initiator to form a second solution; heating the first solution, dropwise adding the second solution while stirring, continuing the reaction after the addition is complete, and removing the organic solvent under reduced pressure to obtain the multi-functional graft monomer. However, the graft monomer prepared by this technology is mainly used to reduce the gel content and increase the grafting rate, and the melt strength performance and shrinkage rate performance of this EPDM are not reflected. Summary of the Invention

[0014] The purpose of the present invention is to provide a polypropylene material with high melt strength and low shrinkage rate and its preparation method, to solve the disadvantages and deficiencies of the prior art. This polypropylene material has the performance characteristics of high melt strength and low shrinkage rate, and can have good forming and sag resistance effects during the material processing, and can be applied to forming processing fields such as thermoforming, blow molding, and foaming.

[0015] To achieve the above object, the present invention provides a polypropylene material with high melt strength and low shrinkage rate. By weight percentage, this polypropylene material includes:

[0016]

[0017] Among them, the graft monomer is prepared from a polyol acrylate compound and an amino sugar alcohol compound.

[0018] For the polypropylene material with high melt strength and low shrinkage rate of the present invention, the preparation method of the graft monomer includes the following steps:

[0019] Adding the polyol acrylate compound and the amino sugar alcohol compound to a solvent, adding a radical initiator, reacting, cooling, precipitating, and filtering to obtain the graft monomer.

[0020] For the polypropylene material with high melt strength and low shrinkage rate of the present invention, the polyol acrylate compound is at least one of trimethylolpropane triacrylate, sorbitol pentaacrylate, and 2,2-dimethyl-1,3-propanediyl diacrylate.

[0021] For the polypropylene material with high melt strength and low shrinkage rate of the present invention, the amino sugar alcohol compound is at least one of D-lyxosamine, 1-amino-1-deoxy-D-mannitol, and 2-amino-2-deoxyglucitol.

[0022] The high melt strength and low shrinkage polypropylene material of the present invention, wherein the polypropylene is at least one of homopolypropylene and copolymerized polypropylene. Preferably, the melt flow rate of the polypropylene at 230 °C under a load of 2.16 Kg is 0.5-50 g / 10 min.

[0023] The high melt strength and low shrinkage polypropylene material of the present invention, wherein the polar monomer is at least one of acrylamide compounds and vinyl pyridine compounds. Preferably, the polar monomer is at least one of N-methyl-2-acrylamide, N,N'-vinyl bisacrylamide, and 4-vinyl pyridine, and the addition amount of the polar monomer is 0.1 wt%-10 wt%.

[0024] The high melt strength and low shrinkage polypropylene material of the present invention, wherein the organic peroxide initiator includes but is not limited to at least one of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane (101), 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxynonane (301), di-tert-butyl peroxide (DTBP), and tert-butyl peroxybenzoate. Preferably, the organic peroxide initiator is at least one of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane (101) and di-tert-butyl peroxide (DTBP), and the addition amount of the organic peroxide initiator is 0.05 wt%-1.5 wt%.

[0025] The high melt strength and low shrinkage polypropylene material of the present invention, wherein the nucleating agent is at least one of organic phosphoric acid metal salts, fatty carboxylic acid metal salts, aromatic carboxylic acid metal salts, and sorbitol compounds and their derivatives. Preferably, the nucleating agent is at least one of NA-21, HPN-20E, HPN-900ei, HPN-500ei, and NX8000, and the addition amount of the nucleating agent is 0.05 wt%-1 wt%.

[0026] The high melt strength and low shrinkage polypropylene material of the present invention, wherein the antioxidant is a mixture of a primary antioxidant and a secondary antioxidant, and the mass ratio of the primary antioxidant to the secondary antioxidant is 0.5-2.

[0027] The high melt strength and low shrinkage polypropylene material of the present invention, wherein the primary antioxidant is preferably a hindered amine antioxidant or a hindered phenol antioxidant, including but not limited to at least one of pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (antioxidant 1010), N,N'-1,3-propylene bis[3,5-di-tert-butyl-4-hydroxybenzamide] (antioxidant 1019), and N,N'-bis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine (antioxidant 1024).

[0028] The high melt strength and low shrinkage polypropylene material of the present invention, the secondary antioxidant is preferably a phosphite ester or a thiodipropionate antioxidant, including but not limited to at least one of tris(2,4-di-tert-butylphenyl) phosphite (antioxidant 168) and [[(dodecylthio)-propionyloxy]methyl]-1,3-propanediol ester (antioxidant 412S). Preferably, the antioxidant is a mixture of primary antioxidant 1010 and secondary antioxidant 168, and the addition amount of the antioxidant is 0.05wt% to 0.6wt%.

[0029] The high melt strength and low shrinkage polypropylene material of the present invention, the slip agent is at least one of calcium stearate, zinc stearate and high melting point paraffin. Preferably, the slip agent is calcium stearate, and the addition amount of the slip agent is 0.05wt% to 2wt%.

[0030] In the preparation method of the graft monomer of the high melt strength and low shrinkage polypropylene material of the present invention, the solvent is at least one of methanol, isopropanol, acetone and dichloromethane.

[0031] In the preparation method of the graft monomer of the high melt strength and low shrinkage polypropylene material of the present invention, the free radical initiator is at least one of azobisisobutyronitrile (AIBN) and benzoyl peroxide (BPO).

[0032] The high melt strength and low shrinkage polypropylene material of the present invention, preferably, the free radical initiator is a mixture of azobisisobutyronitrile (AIBN) and benzoyl peroxide (BPO), and the molar ratio of the two is 0.1 to 5.

[0033] In the preparation method of the graft monomer of the high melt strength and low shrinkage polypropylene material of the present invention, the temperature of the reaction is 30 to 80°C, preferably 40 to 70°C, and the time is 3 to 5 hours.

[0034] The present invention also provides a preparation method of a high melt strength and low shrinkage polypropylene material, comprising the following steps:

[0035] (1) Adding a polyol acrylate compound and an amino sugar alcohol compound into a solvent, adding a free radical initiator, reacting, cooling, precipitating and filtering to obtain a graft monomer;

[0036] (2) Mixing polypropylene, an organic peroxide initiator, a nucleating agent, an antioxidant and a slip agent evenly and adding them into the first feeding port of a twin-screw extruder, mixing the graft monomer and a polar monomer evenly and adding them into the second feeding port of the twin-screw extruder, and then extruding and pelletizing through a melt reaction to obtain a high melt strength and low shrinkage polypropylene material.

[0037] The preparation method of the present invention is such that the temperatures of each section in the twin-screw extruder are 190°C to 260°C, the rotational speed is 50 to 600 rpm, and the feeding speeds of each feeding device are 10 to 100 rpm. Preferably, the screw rotational speed is 100 to 400 rpm, the feeding speed of the first feeding port is 15 to 40 rpm, and the feeding speed of the second feeding port is 15 to 40 rpm.

[0038] The high melt strength and low shrinkage polypropylene material provided by the present invention improves the melt strength of the polypropylene material on the one hand and reduces the shrinkage rate of the polypropylene material on the other hand. The graft monomers added in the present invention are prepared from polyol acrylate compounds and amino sugar alcohol compounds, and have a molecular structure with multiple functional groups and high degree of branching. Under the action of an organic peroxide initiator, they carry out grafting reactions with polypropylene and polar monomers, forming a long-chain cross-linked and interpenetrating network structure connected by graft monomers and polar monomers between the polypropylene molecular chains, strengthening the entanglement ability between the molecular chains and improving the melt strength of the polypropylene material.

[0039] The present invention utilizes the synergistic effect of the highly branched molecular chain structure and the nucleating agent to reduce the shrinkage rate of the polypropylene material. The highly branched molecular chain structure reduces the crystallization ability of the polypropylene material, and the nucleating agent reduces the formation of large spherulites. The two act synergistically to improve the rigidity and heat resistance of the polypropylene material and reduce the shrinkage rate of the polypropylene material. Specific Embodiments

[0040] The following provides a detailed description of the embodiments of the present invention: These embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation manners and processes are given, but the protection scope of the present invention is not limited to the following embodiments.

[0041] The main raw materials used in the embodiments and comparative examples of the present invention are all commercially available, and the raw materials and their sources are as follows:

[0042] Homopolypropylene or copolymer polypropylene, melt flow rate at 230°C under a load of 2.16 Kg is 0.5 to 50 g / 10 min;

[0043] Trimethylolpropane triacrylate, Alfa Aesar, purity: 99%;

[0044] Sorbitol pentaacrylate, Alfa Aesar, purity: 99%;

[0045] 2,2-Dimethyl-1,3-propanediyl diacrylate, Alfa Aesar, purity: 99%;

[0046] D-lyxosamine, Alfa Aesar, purity: 99%;

[0047] 1-Amino-1-deoxy D-mannitol, AlfaAesar, purity: 99%;

[0048] 2-Amino-2-deoxyglucitol, AlfaAesar, purity: 99%;

[0049] Methanol, isopropanol, acetone, dichloromethane, Aladdin Biochemical, purity: 99%;

[0050] Azobisisobutyronitrile, Aladdin Biochemical, purity: 99%;

[0051] Benzoyl peroxide, Aladdin Biochemical, purity: 99%;

[0052] Maleic anhydride, N-methyl-2-acrylamide, N,N'-vinylbisacrylamide, Aladdin Biochemical, purity: 99%;

[0053] 4-vinylpyridine, Aladdin Biochemical, purity: 99%;

[0054] 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane, di-tert-butyl peroxide, McLean, purity: 93%;

[0055] 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxynonane, tert-butyl peroxybenzoate, Anaiji, purity: 97%;

[0056] Nucleating agent NA-21, ADEKA Company, Japan;

[0057] Nucleating agents HPN-20E, HPN-900ei, HPN-500ei, NX8000, Milliken, USA;

[0058] Antioxidant 1010, Antioxidant 168, Calcium Stearate, Beijing Jiyi Chemical Co., Ltd.;

[0059] Antioxidant 1019, Antioxidant 1024, Antioxidant 412S, Zinc Stearate, High Melting Point Paraffin, Beijing Bailingwei Technology Co., Ltd.

[0060] Evaluation and analysis methods:

[0061] The twin-screw extruder used in the polymer reactive extrusion of the present invention is manufactured by LABTECH, with a specification model of LTE26-40.

[0062] The melt strength was tested using the RHEOTENS 71.97 melt strength tester from Goettfert, Germany, at a test temperature of 180°C, an initial speed of 25 mm / s, and a test acceleration of 15 mm / s 2 .

[0063] The injection - molded test specimens were made using an Engel Victory 80spex PRO injection - molding machine. The injection temperatures were set as: 190°C, 200°C, 215°C, 215°C, 200°C, the holding pressure was 55 MPa, the holding time was 50 s, and the cooling time was 10 s.

[0064] The physical properties of the injection - molded samples were tested according to the corresponding national standards: the shrinkage rate was tested according to GB / T17037.4 - 2003; the tensile strength was tested according to GB / T1040 - 2006; the flexural modulus was tested according to GB / T9341 - 2000.

[0065] Example 1

[0066] (1) Weigh 59.3 g of trimethylolpropane triacrylate and 48.2 g of D - lyxosamine and add them to 300 ml of methanol solution. Add 1.6 g of azobisisobutyronitrile and 3.8 g of benzoyl peroxide, and stir - react at 50°C under normal pressure for 4 hours. After cooling, precipitation, and filtration, the graft monomer was obtained and denoted as A1.

[0067] (2) Weigh 86.8 wt% of copolymerized polypropylene, 0.1 wt% of 3,6,9 - triethyl - 3,6,9 - trimethyl - 1,4,7 - triperoxynonane, 0.2 wt% of NA - 21, 0.1 wt% of primary antioxidant 1019, 0.1 wt% of secondary antioxidant 168, and 0.2 wt% of zinc stearate. After mixing evenly according to the ratio, add them into the first feeding port of the twin - screw extruder; weigh 7.5 wt% of graft monomer A1 and 5 wt% of 4 - vinylpyridine, and after mixing evenly according to the ratio, add them into the second feeding port of the screw extruder.

[0068] (3) Set the temperatures of each section of the twin - screw extruder from the feeding port to the head as: 190°C, 195°C, 200°C, 210°C, 210°C, 210°C, 210°C, 200°C, 195°C, 190°C. The screw speed was 200 rpm, the feeding speed of the first feeding port was 25 rpm, and the feeding speed of the second feeding port was 25 rpm. After melting and extruding the above - mentioned raw materials through the twin - screw extruder, high - melt - strength and low - shrinkage - rate polypropylene materials were obtained after cooling, drying, pelletizing, and degassing. The performance test results are shown in Table 1.

[0069] Example 2

[0070] (1) Weigh 29.6 g of trimethylolpropane triacrylate and 35.6 g of 1 - amino - 1 - deoxy - D - mannitol and add them to 300 ml of isopropanol solution. Add 0.82 g of azobisisobutyronitrile and 2.2 g of benzoyl peroxide, and stir - react at 50°C under normal pressure for 4 hours. After cooling, precipitation, and filtration, the graft monomer was obtained and denoted as A2.

[0071] (2) Weigh 85.25 wt% of homopolypropylene, 0.2 wt% of di-tert-butyl peroxide, 0.15 wt% of HPN-20E, 0.1 wt% of primary antioxidant 1010, 0.1 wt% of secondary antioxidant 168, and 0.2 wt% of calcium stearate. After mixing them evenly according to the ratio, add them into the first feeding port of the twin-screw extruder; weigh 8 wt% of graft monomer A2 and 6 wt% of N,N'-divinylbismethacrylamide. After mixing them evenly according to the ratio, add them into the second feeding port of the screw extruder.

[0072] (3) Set the temperatures of each section of the twin-screw extruder from the feeding port to the head: 190 °C, 195 °C, 200 °C, 210 °C, 210 °C, 210 °C, 210 °C, 200 °C, 195 °C, 190 °C. The screw speed is 220 rpm, the feeding speed of the first feeding port is 20 rpm, and the feeding speed of the second feeding port is 25 rpm. After melting and extruding the above raw materials through the twin-screw extruder, cool, dry, pelletize, and degas them to obtain a high melt strength and low shrinkage rate polypropylene material. The performance test results are shown in Table 1.

[0073] Example 3

[0074] (1) Weigh 45.2 grams of sorbitol pentaacrylate and 60.3 grams of 1-amino-1-deoxy-D-mannitol and add them to 350 ml of acetone solution. Add 0.95 grams of azobisisobutyronitrile and 1.8 grams of benzoyl peroxide, and stir and react at 40 °C under normal pressure for 5 hours. After cooling, precipitation, and filtration, obtain the graft monomer, denoted as A3.

[0075] (2) Weigh 84.95 wt% of homopolypropylene, 0.1 wt% of tert-butyl perbenzoate, 0.1 wt% of HPN-20E, 0.05 wt% of HPN-900ei, 0.1 wt% of primary antioxidant 1024, 0.1 wt% of secondary antioxidant 168, and 0.1 wt% of high melting point paraffin. After mixing them evenly according to the ratio, add them into the first feeding port of the twin-screw extruder; weigh 7 wt% of graft monomer A3 and 7.5 wt% of N-methyl-2-acrylamide. After mixing them evenly according to the ratio, add them into the second feeding port of the screw extruder.

[0076] (3) Set the temperatures of each section of the twin-screw extruder from the feeding port to the head: 190 °C, 195 °C, 200 °C, 210 °C, 210 °C, 210 °C, 210 °C, 200 °C, 195 °C, 190 °C. The screw speed is 300 rpm, the feeding speed of the first feeding port is 25 rpm, and the feeding speed of the second feeding port is 30 rpm. After melting and extruding the above raw materials through the twin-screw extruder, cool, dry, pelletize, and degas them to obtain a high melt strength and low shrinkage rate polypropylene material. The performance test results are shown in Table 1.

[0077] Example 4

[0078] (1) Weigh 45.2 g of sorbitol pentaacrylate and 53.5 g of 2-amino-2-deoxyglucitol, add them to 300 ml of methanol solution, add 0.75 g of azobisisobutyronitrile and 1.1 g of benzoyl peroxide, stir and react at 60 °C under normal pressure for 4 hours, and obtain the graft monomer by cooling, precipitation and filtration, denoted as A4.

[0079] (2) Weigh 83.89 wt% of copolymerized polypropylene, 0.1 wt% of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 0.08 wt% of HPN-20E, 0.08 wt% of HPN-500ei, 0.1 wt% of primary antioxidant 1010, 0.05 wt% of secondary antioxidant 168, 0.2 wt% of calcium stearate, mix them evenly according to the ratio and add them into the first feeding port of the twin-screw extruder; weigh 8 wt% of graft monomer A4 and 7.5 wt% of N-methyl-2-acrylamide, mix them evenly according to the ratio and add them into the second feeding port of the screw extruder.

[0080] (3) Set the temperatures of each section of the twin-screw extruder from the feeding port to the head: 190 °C, 195 °C, 200 °C, 210 °C, 210 °C, 210 °C, 210 °C, 200 °C, 195 °C, 190 °C, the screw speed is 300 rpm, the feeding speed of the first feeding port is 25 rpm, and the feeding speed of the second feeding port is 25 rpm. After melting and extruding the above raw materials through the twin-screw extruder, cooling, drying, pelletizing and degassing treatment are carried out to obtain the high melt strength and low shrinkage polypropylene material. The performance test results are shown in Table 1.

[0081] Example 5

[0082] (1) Weigh 36.4 g of 2,2-dimethyl-1,3-propanediyl diacrylate and 46.8 g of 2-amino-2-deoxyglucitol, add them to 350 ml of dichloromethane solution, add 0.86 g of azobisisobutyronitrile and 1.58 g of benzoyl peroxide, stir and react at 60 °C under normal pressure for 4 hours, and obtain the graft monomer by cooling, precipitation and filtration, denoted as A5.

[0083] (2) Weigh 82.85 wt% of copolymerized polypropylene, 0.1 wt% of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 0.05 wt% of HPN-20E, 0.2 wt% of NX8000, 0.1 wt% of primary antioxidant 1010, 0.1 wt% of secondary antioxidant 412S, 0.1 wt% of calcium stearate, mix them evenly according to the ratio and add them into the first feeding port of the twin-screw extruder; weigh 10 wt% of graft monomer A5 and 6.5 wt% of N,N'-vinyl bisacrylamide, mix them evenly according to the ratio and add them into the second feeding port of the screw extruder.

[0084] (3) Set the temperatures of each section of the twin-screw extruder from the feeding port to the die head as follows: 190 °C, 195 °C, 200 °C, 210 °C, 210 °C, 210 °C, 210 °C, 200 °C, 195 °C, 190 °C. The screw speed is 300 rpm, the feeding speed at the first feeding port is 25 rpm, and the feeding speed at the second feeding port is 30 rpm. After melting and extruding the above raw materials through the twin-screw extruder, they are cooled, dried, pelletized, and degassed to obtain a polypropylene material with high melt strength and low shrinkage rate. The performance test results are shown in Table 1.

[0085] Example 6

[0086] (1) Weigh 52.6 grams of 2,2-dimethyl-1,3-propanediyl diacrylate and 63.5 grams of 2-amino-2-deoxyglucitol and add them to 750 ml of dichloromethane solution. Add 2.86 grams of azobisisobutyronitrile and 2.47 grams of benzoyl peroxide, and stir and react at 60 °C under normal pressure for 4 hours. After cooling, precipitation, and filtration, the graft monomer is obtained and denoted as A6.

[0087] (2) Weigh 68.75 wt% of copolymerized polypropylene, 0.8 wt% of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 0.2 wt% of HPN-20E, 0.4 wt% of NX8000, 0.15 wt% of primary antioxidant 1010, 0.1 wt% of secondary antioxidant 412S, and 0.1 wt% of calcium stearate. After mixing them evenly according to the ratio, add them into the first feeding port of the twin-screw extruder; weigh 18 wt% of graft monomer A6 and 11.5 wt% of N,N'-vinyl bisacrylamide, and after mixing them evenly according to the ratio, add them into the second feeding port of the screw extruder.

[0088] (3) Set the temperatures of each section of the twin-screw extruder from the feeding port to the die head as follows: 190 °C, 195 °C, 200 °C, 215 °C, 215 °C, 215 °C, 215 °C, 200 °C, 195 °C, 190 °C. The screw speed is 400 rpm, the feeding speed at the first feeding port is 25 rpm, and the feeding speed at the second feeding port is 40 rpm. After melting and extruding the above raw materials through the twin-screw extruder, they are cooled, dried, pelletized, and degassed to obtain a polypropylene material with high melt strength and low shrinkage rate. The performance test results are shown in Table 1.

[0089] Comparative Example 1

[0090] The difference from Example 4 is that no graft monomer, nucleating agent, polar monomer, or organic peroxide initiator is added.

[0091] (1) Weigh 99.65 wt% of homopolypropylene, 0.1 wt% of primary antioxidant 1010, 0.05 wt% of secondary antioxidant 168, and 0.2 wt% of calcium stearate. After mixing evenly according to the ratio, add them into the first feeding port of the twin-screw extruder.

[0092] (3) Set the temperatures of each section of the twin-screw extruder from the feeding port to the head: 190 °C, 195 °C, 200 °C, 210 °C, 210 °C, 210 °C, 210 °C, 200 °C, 195 °C, 190 °C. The screw speed is 300 rpm, and the feeding speed of the first feeding port is 25 rpm. After melting and extruding the above raw materials through the twin-screw extruder, cool, dry, pelletize, and degas to obtain the polypropylene material of Comparative Example 1. The performance test results are shown in Table 1.

[0093] Comparative Example 2

[0094] The difference from Example 4 is that graft monomers, polar monomers, and organic peroxide initiators are not added.

[0095] (1) Weigh 99.49 wt% of copolymerized polypropylene, 0.08 wt% of HPN-20E, 0.08 wt% of HPN-500ei, 0.1 wt% of primary antioxidant 1010, 0.05 wt% of secondary antioxidant 168, and 0.2 wt% of calcium stearate. After mixing evenly according to the ratio, add them into the first feeding port of the twin-screw extruder.

[0096] (3) Set the temperatures of each section of the twin-screw extruder from the feeding port to the head: 190 °C, 195 °C, 200 °C, 210 °C, 210 °C, 210 °C, 210 °C, 200 °C, 195 °C, 190 °C. The screw speed is 300 rpm, and the feeding speed of the first feeding port is 25 rpm. After melting and extruding the above raw materials through the twin-screw extruder, cool, dry, pelletize, and degas to obtain the polypropylene material of Comparative Example 2. The performance test results are shown in Table 1.

[0097] Comparative Example 3

[0098] The difference from Example 4 is that unsaturated acid anhydride maleic anhydride is used to replace 2-amino-2-deoxyglucitol in the preparation process of graft monomers.

[0099] (1) Weigh 38.4 grams of sorbitol pentaacrylate and 28.5 grams of maleic anhydride, add them to 400 ml of methanol solution, add 0.52 grams of azobisisobutyronitrile and 1.4 grams of benzoyl peroxide, stir and react at 60 °C under normal pressure for 4 hours, and obtain the graft monomer by cooling, precipitation, and filtration, denoted as D1.

[0100] (2) Weigh 83.89 wt% of the copolymerized polypropylene, 0.1 wt% of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 0.08 wt% of HPN-20E, 0.08 wt% of HPN-500ei, 0.1 wt% of the primary antioxidant 1010, 0.05 wt% of the secondary antioxidant 168, and 0.2 wt% of calcium stearate. After mixing them evenly according to the ratio, add them into the first feeding port of the twin-screw extruder; weigh 8 wt% of the graft monomer D1 and 7.5 wt% of N-methyl-2-acrylamide. After mixing them evenly according to the ratio, add them into the second feeding port of the screw extruder.

[0101] (3) Set the temperatures of each section of the twin-screw extruder from the feeding port to the head: 190 °C, 195 °C, 200 °C, 210 °C, 210 °C, 210 °C, 210 °C, 200 °C, 195 °C, 190 °C. The screw speed is 300 rpm, the feeding speed of the first feeding port is 25 rpm, and the feeding speed of the second feeding port is 25 rpm. After melting and extruding the above raw materials through the twin-screw extruder, perform cooling, drying, pelletizing, and degassing treatments to obtain the polypropylene material of Comparative Example 3. The performance test results are shown in Table 1.

[0102] Table 1 Performance Test Results of Polypropylene Materials in Examples and Comparative Examples

[0103]

[0104] As can be seen from Table 1, compared with Comparative Examples 1-3, the melt strength of the polypropylene materials prepared in Examples 1-6 has been greatly improved, and the anisotropic shrinkage rate has been significantly reduced. The high melt strength and low shrinkage polypropylene material prepared by the present invention can meet the application requirements of extrusion, thermoforming, blow molding, foaming and other forming processes.

[0105] Of course, the present invention can also have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding changes and deformations should all fall within the protection scope of the present invention.

Claims

1. A high melt strength and low shrinkage polypropylene material, characterized in that: Calculated by weight percentage, including: Wherein, the grafting monomer is prepared from polyol acrylate compounds and aminosugar alcohol compounds.

2. The high melt strength and low shrinkage polypropylene material according to claim 1, characterized in that: The preparation method of the grafted monomer comprises the following steps: The polyol acrylate compound and the aminosugar alcohol compound are added into a solvent, a free radical initiator is added, the reaction is carried out, and the precipitation is cooled and filtered to obtain the grafting monomer.

3. The high melt strength and low shrinkage polypropylene material according to claim 1, characterized in that: The polyol acrylate compound is at least one of trimethylolpropane triacrylate, sorbitol pentaacrylate and 2,2-dimethyl-1,3-propane diyl diacrylate.

4. The high melt strength and low shrinkage polypropylene material according to claim 1, characterized in that: The aminosugar alcohol compound is at least one of D-lyxosamine, 1-amino-1-deoxy D-mannitol and 2-amino-2-deoxyglucitol.

5. The high melt strength and low shrinkage polypropylene material according to claim 1, characterized in that: The polypropylene is at least one of homopolypropylene and copolymer polypropylene.

6. The high melt strength and low shrinkage polypropylene material according to claim 1, characterized in that: The polar monomer is at least one of an acrylamide compound and a vinyl pyridine compound.

7. The high melt strength and low shrinkage polypropylene material according to claim 1, characterized in that: The organic peroxide initiator is at least one of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (101), 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxynonane (301), di-tert-butyl peroxide (DTBP) and tert-butyl peroxybenzoate.

8. The high melt strength and low shrinkage polypropylene material according to claim 1, characterized in that: The nucleating agent is at least one of an organic phosphate metal salt, a fatty carboxylic acid metal salt, an aromatic carboxylic acid metal salt, a sorbitol compound and a derivative thereof.

9. The high melt strength and low shrinkage polypropylene material according to claim 1, characterized in that: The antioxidant is a mixture of a main antioxidant and an auxiliary antioxidant, and the mass ratio of the main antioxidant to the auxiliary antioxidant is 0.5-2.

10. The high melt strength and low shrinkage polypropylene material according to claim 9, characterized in that: The primary antioxidant is at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], N,N'-1,3-propylenebis[3,5-di-tert-butyl-4-hydroxyphenylpropionamide] and N,N'-bis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine.

11. The high melt strength and low shrinkage polypropylene material according to claim 9, characterized in that: The auxiliary antioxidant is at least one of tris(2,4-di-tert-butylphenyl)phosphite and (dodecylthio)-propionyloxy]methyl]-1,3-propylene glycol ester.

12. The high melt strength and low shrinkage polypropylene material according to claim 1, characterized in that: The lubricant is at least one of calcium stearate, zinc stearate and high melting point paraffin.

13. The high melt strength and low shrinkage polypropylene material according to claim 2, characterized in that: The solvent is at least one of methanol, isopropanol, acetone and dichloromethane.

14. The high melt strength and low shrinkage polypropylene material according to claim 2, characterized in that: The free radical initiator is at least one of azobisisobutyronitrile (AIBN) and benzoyl peroxide (BPO).

15. The high melt strength and low shrinkage polypropylene material according to claim 14, characterized in that: The free radical initiator is a mixture of azobisisobutyronitrile (AIBN) and benzoyl peroxide (BPO), and the molar ratio of the two is 0.1-5.

16. A method for preparing a polypropylene material with high melt strength and low shrinkage, characterized in that: The following steps are involved: (1) adding a polyol acrylate compound and an aminosugar alcohol compound into a solvent, adding a free radical initiator, reacting, cooling, precipitating and filtering to obtain a grafted monomer; (2) Polypropylene, organic peroxide initiator, nucleating agent, antioxidant and lubricant are mixed evenly and then added to the first feed port of a twin-screw extruder; grafted monomer and polar monomer are mixed evenly and then added to the second feed port of the twin-screw extruder; then extrusion granulation is performed through a melt reaction to obtain a polypropylene material with high melt strength and low shrinkage.

17. The preparation method according to claim 16, characterized in that: The temperature of each section in the twin-screw extruder is 190° C. to 260° C., the rotation speed is 50 to 600 rpm, and the feeding speed of each feeding device is 10 to 100 rpm.

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