Polypropylene beta-crystal-form compound nucleating agent, beta-crystal-form homo-polypropylene pipe special material and production process of beta-crystal-form homo-polypropylene pipe special material

Abstract

The invention discloses a polypropylene beta crystal form compound nucleating agent, a beta crystal form homo-polypropylene pipe special material and a production process thereof, and belongs to the technical field of polypropylene materials. The polypropylene beta crystal form compound nucleating agent disclosed by the invention is prepared from the following components in percentage by weight: 15 to 20 percent of beta crystal form nucleating agent, 60 to 70 percent of antioxidant, 7 to 11 percent of calcium stearate and 5 to 10 percent of polyphthalamide. The polypropylene beta crystal form compound nucleating agent has the advantages of high beta crystal form conversion rate, high rigidity, low dosage, good dispersity and the like, and the normal and low temperature impact strength of the material can be greatly improved. The beta crystal form homo-polypropylene pipe special material product obtained by the production process has excellent impact strength, thermal deformation temperature and flexural modulus performance, also has excellent processability, and is suitable for the fields of chemical pressure pipelines and pipe fittings, extrusion and compression molded plates, filter plates and solid rods.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of polypropylene materials, and particularly relates to a polypropylene beta crystal type compounded nucleating agent and a beta crystal type homopolymer polypropylene pipe material special material and a production process thereof. BACKGROUND

[0002] Under conventional polypropylene production conditions, the main product is alpha crystal type, and the alpha crystal type polypropylene has good rigidity and strength, but has the problem of poor toughness. The toughness of beta crystal type polypropylene is significantly better than that of alpha crystal type polypropylene, and the impact strength of the beta crystal type polypropylene is several times higher than that of the alpha crystal type polypropylene. Under the premise that the modulus and strength of the beta crystal type polypropylene are not much different from those of pure polypropylene, the beta crystal type polypropylene can significantly improve the toughness and heat distortion temperature. The spherulites of the alpha crystal type polypropylene have obvious boundaries, and the spherulite size is several times larger than that of the beta crystal type. The lamellar beam grows radially from the center of the spherulite. The spherulite boundaries of the beta crystal type polypropylene are blurred and penetrate each other, and the spherulite size is much smaller than that of the alpha crystal type. When the beta crystal type polypropylene encounters external impact, it is easy to induce the formation of silver lines to absorb energy, so its impact toughness is relatively good. In addition to maintaining the good comprehensive performance of the alpha crystal type polypropylene, the elongation at break and notched impact strength of the beta crystal type polypropylene are several times higher than those of the alpha crystal type polypropylene, and the heat distortion temperature can also be greatly improved.

[0003] The beta crystal type homopolymer polypropylene material can significantly improve the comprehensive mechanical properties of polypropylene. At present, there are many types of polypropylene products in China, but there are fewer high-value-added beta crystal type polypropylene product brands. Accelerating the development process of domestic beta crystal type polypropylene products to replace imported products is the only way to improve the core competitiveness and economic value of polyolefins in China. At present, beta crystal type polypropylene is mainly prepared by adding beta crystal type nucleating agents to polypropylene. The existing beta crystal type nucleating agents are mainly single components, such as single-component dicarboxylic acid salt compounds, amide compounds, and rare earth calcium multi-component complexes. The nucleating efficiency of these nucleating agents is high or low, and the addition of these nucleating agents to polypropylene does not significantly improve the low-temperature impact strength of the product. Therefore, in order to better improve the impact strength of the product, the addition amount of the beta crystal type nucleating agent is high.

[0004] Therefore, it is necessary to provide a polypropylene beta crystal type compounded nucleating agent to solve the problems of low nucleating efficiency of the existing beta crystal type nucleating agent and poor improvement of the impact strength of the product, and to provide a beta crystal type homopolymer polypropylene pipe material special material, which can simultaneously consider the strength and toughness of the material, so as to improve the toughness of the polypropylene material without reducing the comprehensive performance. SUMMARY

[0005] The main purpose of the present application is to provide a polypropylene beta crystal form compounded nucleating agent and a beta crystal form homopolymer polypropylene pipe material special material and its production process, the dispersion of the provided polypropylene beta crystal form compounded nucleating agent is good, the performance is excellent, and the problems of low nucleating efficiency, high dosage, poor impact strength performance improvement of the existing beta crystal form nucleating agent can be solved; the temperature resistance and pressure resistance grade of the traditional PPR and PPB pipe material special material is not high, thereby limiting its application range, the beta crystal form homopolymer polypropylene pipe material special material provided by the present application is a homopolymer polypropylene prepared by adding a polypropylene beta crystal form compounded nucleating agent and a special process of the present application, which can simultaneously have better impact strength, heat distortion temperature and bending modulus performance, and also has excellent processing performance, and is suitable for chemical pressure pipes and pipe fittings, extrusion and compression mold plates, filter plates and solid rod fields.

[0006] In order to achieve the above-mentioned purpose, the present application provides a polypropylene beta crystal form compounded nucleating agent, which comprises the following components according to 100% by weight: 15-20% of a beta crystal form nucleating agent, 60-70% of an antioxidant, 7-11% of calcium stearate and 5-10% of polyphthalamide.

[0007] The present application is aimed at the high performance requirement of the PPH pipe material, the nucleating agent system adopts beta crystal form nucleating agent, antioxidant, calcium stearate and polyphthalamide for compounding, and the dosages of the components are specifically designed, and the components synergistically act, so that when the components are applied to the PPH pipe material, the material has excellent processing performance and can greatly improve the impact strength at room temperature and low temperature of the material. The present application selects the beta crystal form nucleating agent to induce polypropylene crystallization, and cooperatively adds polyphthalamide, which has good high temperature resistance and can be used as a molecular internal lubricant, can effectively reduce the torque in the extrusion process of polypropylene product production, improve the processing performance of low melt index resin, eliminate pipe melt rupture, add calcium stearate to improve the processing performance of the product, absorb the acid generated in the industrialized production process of the polypropylene product, ensure that the product raw material is odorless, and add the antioxidant to further improve the high temperature resistance and anti-aging performance of the product.

[0008] Further, the beta crystal form nucleating agent is selected from a rare earth beta crystal form nucleating agent and / or an aromatic amide beta crystal form nucleating agent.

[0009] Further, the antioxidant is selected from a hindered phenol antioxidant and / or a phosphite antioxidant.

[0010] In one aspect of the present application, a beta crystal form homopolymer polypropylene pipe material special material is also provided, which comprises the aforementioned polypropylene beta crystal form compounded nucleating agent and homopolymer polypropylene.

[0011] Further, the mass ratio of the polypropylene beta crystal form compounded nucleating agent to the homopolymer polypropylene is 1:120-170.

[0012] Another aspect of the present application also provides a production process of the beta crystal form homopolypropylene pipe special material, which comprises the following steps: blending the homopolypropylene with the aforementioned polypropylene beta crystal form complex nucleating agent, and sequentially melting, extruding and granulating to obtain the beta crystal form homopolypropylene pipe special material.

[0013] Further, the addition amount of the polypropylene beta crystal form complex nucleating agent is 5500-8000 ppm.

[0014] Further, the homopolypropylene is prepared by the following method: step S1, pre-polymerization reaction of a catalyst and propylene to obtain a pre-polymerization product; and step S2, homopolymerization reaction of the pre-polymerization product in a liquid-phase double-loop reactor under the action of a catalyst to obtain the homopolypropylene.

[0015] Further, in the steps S1 and S2, the catalyst is configured by a main catalyst, a co-catalyst and an external electron donor, the main catalyst is DJD-2-B type catalyst, the co-catalyst is triethylaluminum, and the external electron donor is cyclohexyl methyl dimethoxysilane.

[0016] Further, in the step S1, the pre-polymerization reaction conditions are as follows: pre-polymerization temperature is 15-21℃, pressure is 3.4-4.5 Mpa, and time is 10-15 min.

[0017] Further, in the step S2, the homopolymerization reaction conditions are as follows: homopolymerization temperature is 69-71℃, pressure is 3.4-4.5 Mpa, and time is 60-70 min.

[0018] The beta crystal form homopolypropylene pipe special material prepared by the present application realizes mass production on a 300,000 tons / year polypropylene Spheripol process device of Daqing Refinery Company, and the product performance reaches the advanced level at home and abroad. The room temperature impact strength of the industrial production product is 87-125 KJ / m 2 , the low temperature impact strength is 4.1-7.9 KJ / m 2 , and the heat distortion temperature is 95-113℃, and the raw material physical property values completely meet the national standard (GB / T18742.2-2017) of beta-PPH.

[0019] Compared with the prior art, the present application has the following beneficial effects:

[0020] (1) The present application proposes a polypropylene beta crystal type compounded nucleating agent aiming at the high performance requirements of PPH pipe material. The nucleating agent system is compounded by beta crystal type nucleating agent, antioxidant, calcium stearate and polyphthalamide. The components synergize with each other. The polypropylene beta crystal type compounded nucleating agent has the advantages of high beta crystal type conversion rate, high rigidity, low dosage, good dispersibility and the like, and can greatly improve the impact strength of the material at room temperature and low temperature.

[0021] (2) The beta crystal type homopolymer polypropylene pipe material special material of the present application is produced by Spheripol loop process. This process can produce pipe material with bimodal distribution of molecular weight, which improves the post-processing performance of the product. The high crystallinity, high rigidity and good uniformity of the homopolymer polypropylene powder produced in the liquid phase double loop reactor are compounded with the polypropylene beta crystal type nucleating agent by melt extrusion granulation. The prepared product greatly improves the poor impact performance of the polypropylene product, so that the beta crystal type homopolymer polypropylene pipe material special material product can simultaneously have good impact strength, heat distortion temperature and bending modulus performance, and also has excellent processing performance, which is suitable for chemical pressure pipes and pipe fittings, extrusion and compression molded plates, filter plates and solid rod fields. DETAILED DESCRIPTION

[0022] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments.

[0023] In one aspect of the present application, a polypropylene beta crystal type compounded nucleating agent is provided, which comprises the following components according to 100% by weight: 15-20% of beta crystal type nucleating agent, 60-70% of antioxidant, 7-11% of calcium stearate and 5-10% of polyphthalamide.

[0024] In a preferred embodiment, the beta crystal type nucleating agent is selected from rare earth beta crystal type nucleating agent and / or aromatic amide beta crystal type nucleating agent. In some alternative embodiments, the rare earth beta crystal type nucleating agent is selected from one or more of WBG nucleating agent (such as Guangzhou Weilinna WBG-II, WBG), WBG and metal element compounded nucleating agent (such as WBG+BaSO 4、 WBG+CaO3). The aromatic amide beta crystal type nucleating agent is selected from one or more of Beijing Jihai River JHC-671, Shanxi Chemical TMB-5.

[0025] In a preferred embodiment, the beta crystal type nucleating agent is selected from one or more of Beijing Jihai River JHC-671, Guangzhou Weilinna WBG-II.

[0026] In some alternative embodiments, the hindered phenolic antioxidant can be selected from antioxidant 1010, antioxidant 330; the phosphite antioxidant can be selected from antioxidant 168. Preferably, the antioxidant is selected from antioxidant 1010, antioxidant 330 and antioxidant 168. Antioxidant 330 is a pipe special antioxidant, resistant to high temperature, resistant to extraction, the inventors found that: antioxidant 168 and antioxidant 1010 and antioxidant 330 have good synergistic effect, and the application of the same to the polypropylene beta crystal form compounded nucleating agent can better improve the performance of the polypropylene product.

[0027] In some alternative embodiments, a polypropylene beta crystal form compounded nucleating agent, consisting of 15% of a beta crystal form nucleating agent, 64% of an antioxidant, 11% of calcium stearate and 10% of polyphthalamide, according to 100% by weight. Or, consisting of 20% of a beta crystal form nucleating agent, 65% of an antioxidant, 10% of calcium stearate and 5% of polyphthalamide.

[0028] In a preferred embodiment, the polypropylene beta crystal form compounded nucleating agent consists of the following components: 17% of a beta crystal form nucleating agent, 69% of an antioxidant, 8% of calcium stearate and 6% of polyphthalamide, according to 100% by weight.

[0029] In a preferred embodiment, the polypropylene beta crystal form compounded nucleating agent is in the form of particles, with a particle size of 0.10-0.15 mm and a length of 0.15-0.3 mm. The polypropylene beta crystal form compounded nucleating agent of the present application is in the form of particles, which is convenient for subsequent industrial production of the beta crystal form homopolypropylene pipe special material, without the need for multiple feeding, and avoiding the problem of wall hanging during feeding, which causes product performance defects.

[0030] In a preferred embodiment, the bulk density of the polypropylene beta crystal form compounded nucleating agent is 0.40-0.60 g / cm 3 (detection standard is GB / T 1636). The acid value of the polypropylene beta crystal form compounded nucleating agent is ≤1.0 mgKOH / g (detection standard is GB / T 14827), and the volatile matter is ≤1.0 (detection standard is GB / T 6284).

[0031] In one aspect of the present application, a beta crystal form homopolypropylene pipe special material is also provided, comprising the aforementioned polypropylene beta crystal form compounded nucleating agent and homopolypropylene.

[0032] In a preferred embodiment, the melt index of the beta crystal form homopolypropylene pipe special material is 0.25-0.37 g / 10 min.

[0033] The present application also provides a production process of the β crystal form homopolypropylene pipe special material, which comprises the following steps: blending the homopolypropylene with the aforementioned polypropylene β crystal form nucleating agent, and then sequentially melting, extruding and granulating to obtain the β crystal form homopolypropylene pipe special material.

[0034] In a preferred embodiment, the melt pressure is 1.1-1.5 MPa and the melt temperature is 210-240°C during the melting process.

[0035] In an alternative embodiment, the sample is extruded and granulated by using a double-screw extruder, and the temperature of each section from the feeding port to the head of the extruder is 190°C, 230°C, 230°C, 230°C, 230°C, 230°C and 210°C, and the main motor speed is 210 rpm.

[0036] In a preferred embodiment, the homopolypropylene is prepared by the following method: step S1, pre-polymerization of the catalyst and propylene to obtain a pre-polymerization product; and step S2, homopolymerization of the pre-polymerization product in a liquid-phase double-loop reactor under the action of the catalyst to obtain the homopolypropylene.

[0037] In a preferred embodiment, the catalyst in steps S1 and S2 is configured by a main catalyst, a co-catalyst and an external electron donor, the main catalyst is DJD-2-B catalyst, the co-catalyst is triethyl aluminum, and the external electron donor is cyclohexyl methyl dimethoxysilane. In the production process, the catalyst system has good hydrogen sensitivity and stability, and the product melt index is stable.

[0038] In a preferred embodiment, the mass ratio of the co-catalyst to propylene (aluminum-propylene ratio) is 0.1%-0.2%, the mass ratio of the co-catalyst to the external electron donor (aluminum-silicon ratio) is 7%-10%, and the mass ratio of the co-catalyst to the main catalyst is 5%-8%.

[0039] In a preferred embodiment, the main catalyst, the co-catalyst and the external electron donor are pre-contacted before step S1 to activate the main catalyst. Preferably, the pre-contacting conditions are a pre-contacting temperature of 10°C-13°C and a pressure of 3.5-3.6 MPa.

[0040] In a preferred embodiment, the pre-contacting reaction of the catalyst is operated under nitrogen protection, and the oil and fat mixture is reacted after entering the pre-contacting tank and pre-polymerized with propylene passing through an online mixer. The oil and fat composition is a mixture of white oil and vaseline with a volume ratio of 2:1.

[0041] In a preferred embodiment, Atmer 163 additive is added in the discharge line of the liquid phase double loop reactor to kill the residual activity of the catalyst in the polypropylene powder. Further preferably, the amount of Atmer 163 additive added is 1-2 kg / h.

[0042] In a preferred embodiment, hydrogen is added in the liquid phase double loop reactor to control the melt index of the β crystal form homopolymer polypropylene pipe special material generated in the reactor. Preferably, the concentration of hydrogen is 210-230 ppm.

[0043] In a preferred embodiment, the powder density of the homopolymer polypropylene obtained in the liquid phase double loop reactor is 550-560 kg / m 3 .

[0044] The β crystal form homopolymer polypropylene pipe special material of the present application is designed with a molecular weight bimodal distribution molecular structure, preferably a good hydrogen sensitivity catalyst system, and improved matching of the main catalyst and external electron donor. At the same time, the influence of key parameters such as polymerization temperature, pressure, hydrogen addition amount, aluminum / silicon ratio, and aluminum / propylene ratio on the performance of the product is investigated to determine the setting of the core process parameters.

[0045] The β crystal form homopolymer polypropylene pipe special material of the present application is produced by the Spheripol loop process, and the process polymerization reactor is a liquid phase double loop reactor. Continuous pre-contacting and pre-polymerization are used to improve the stability of the product, and a high pre-polymerization yield (50-100 gpp / g cat) makes the catalyst particles entering the reactor strong and not produce a large amount of fine powder. This process can produce products with bimodal molecular weight distribution and other high-performance homopolymers. The bimodal distribution of the pipe material is beneficial to improve the post-processing performance of the product. At the same time, the present application controls the reactor pressure from 3.4 MPa to 4.5 MPa, greatly increasing the concentration of dissolved hydrogen in the reactor, and combining with the electron donor and the main catalyst to produce homopolymer polypropylene powder with high crystallinity, high rigidity, and good uniformity. In addition, the present application establishes the relationship between the pipe temperature resistance and creep resistance performance-microscopic crystal structure-polymerization process and additives, determines the type and amount of β crystal form homopolymer polypropylene nucleating agent, and melts and extrudes the homopolymer polypropylene powder to prepare granules. The prepared product greatly improves the poor impact performance of polypropylene products, and the β crystal form homopolymer polypropylene pipe special material product has excellent low temperature impact resistance, high rigidity and heat distortion temperature, and good post-processing performance.

[0046] The present application will be further described in detail below in conjunction with specific examples, which cannot be understood as limiting the scope of the present application.

[0047] Example 1

[0048] A polypropylene beta crystal form compounded nucleating agent is composed of 17% of WBG-II (Guangzhou Weilin), 30% of antioxidant 1010, 20% of antioxidant 330, 19% of antioxidant 168, 8% of calcium stearate and 6% of polyphthalamide.

[0049] A beta crystal form homopolymer polypropylene pipe special material is composed of the aforementioned polypropylene beta crystal form compounded nucleating agent and homopolymer polypropylene. The mass ratio of the polypropylene beta crystal form compounded nucleating agent to the homopolymer polypropylene is 1:120.

[0050] A production process of a beta crystal form homopolymer polypropylene pipe special material includes the following steps: homopolymer polypropylene base powder (marketed qualified product powder) is uniformly mixed with the polypropylene beta crystal form compounded nucleating agent in a high-speed mixer, and the sample is melt-extruded and granulated through a double-screw extruder to obtain the beta crystal form homopolymer polypropylene pipe special material. The addition amount of the polypropylene beta crystal form compounded nucleating agent in the homopolymer polypropylene base powder is 8000 ppm. The temperature of each section from the feeding port to the die of the double-screw extruder is 190℃, 230℃, 230℃, 230℃, 230℃, 230℃, 210℃, the main machine speed is 210 rpm, the melt pressure is 1.3 Mpa, and the melt temperature is 225℃.

[0051] Example 2

[0052] A polypropylene beta crystal form compounded nucleating agent (Beijing Jihaiwan compounded nucleating agent JHC-7601) is composed of 17% of Beijing Jihaiwan beta crystal form nucleating agent JHC-671, 30% of antioxidant 1010, 20% of antioxidant 330, 19% of antioxidant 168, 8% of calcium stearate and 6% of polyphthalamide.

[0053] A beta crystal form homopolymer polypropylene pipe special material is composed of the aforementioned polypropylene beta crystal form compounded nucleating agent and homopolymer polypropylene. The mass ratio of the polypropylene beta crystal form compounded nucleating agent to the homopolymer polypropylene is 1:120.

[0054] The same homopolymer polypropylene base powder (marketed qualified product powder) as in Example 1 is used to produce a beta crystal form homopolymer polypropylene pipe special material with the polypropylene beta crystal form compounded nucleating agent of the present example, and the production process is the same as in Example 1.

[0055] Example 3

[0056] A polypropylene beta crystal form compounded nucleating agent is composed of 17% of TMB-5 (Shanxi Chemical Research Institute), 30% of antioxidant 1010, 20% of antioxidant 330, 19% of antioxidant 168, 8% of calcium stearate and 6% of polyphthalamide.

[0057] A kind of β crystal form homopolypropylene pipe special material for special material, by the polypropylene β crystal form complex nucleating agent of preceding and homopolypropylene.It is 1:120 by mass ratio of polypropylene β crystal form complex nucleating agent and homopolypropylene.

[0058] The same homopolypropylene base powder (marketable qualified powder) of example 1 is used with the polypropylene β crystal form complex nucleating agent of the present example to produce β crystal form homopolypropylene pipe special material for special material, and its production process is the same with example 1.

[0059] Comparative example 1

[0060] A kind of polypropylene complex auxiliary agent, by 40% of antioxidant 1010, 27% of antioxidant 330, 19% of antioxidant 168, 8% of calcium stearate and 6% of polyphthalamide, it does not add aromatic amide and rare earth β crystal form nucleating agent.

[0061] The same homopolypropylene base powder (marketable qualified powder) of example 1 is used with the polypropylene complex auxiliary agent of the present comparative example to produce β crystal form homopolypropylene pipe special material for special material, and its production process is the same with example 1.

[0062] Comparative example 2

[0063] A kind of polypropylene β crystal form complex nucleating agent, by 17% of Beijing Jihaichuan β crystal form nucleating agent JHC-671, 36% of antioxidant 1010, 20% of antioxidant 330, 19% of antioxidant 168 and 8% of calcium stearate, it does not add polyphthalamide.

[0064] The same homopolypropylene base powder (marketable qualified powder) of example 1 is used with the polypropylene β crystal form complex nucleating agent of the present comparative example to produce β crystal form homopolypropylene pipe special material for special material, and its production process is the same with example 1.

[0065] The homopolypropylene pipe special material for special material of above-mentioned example and comparative example is used to produce test sample bar by double screw injection molding machine, and injection molding temperature is set as: 210℃, 255℃, 255℃, 255℃, 220℃.According to national standard GB / T 3682, the test sample bar is tested for melt index, according to national standard GB / T 1040, the test sample bar is tested for tensile strength, according to national standard GB / T 9341, the test sample bar is tested for bending modulus, according to national standard GB / T 1043, the test sample bar is tested for simply supported beam impact strength, according to national standard GB / T 19466, the test sample bar is tested for oxidation induction period.The test results are shown in table 1.

[0066] Table 1

[0067]

[0068] From the above small test results, it can be seen that the notched impact strength performance of Comparative Example 1 without adding the β crystal nucleating agent is the worst, and the notched impact strength performance of Examples 1-3 using the polypropylene β crystal complex nucleating agent of the present application is obviously improved, especially the notched impact strength of Example 2 using the complex nucleating agent JHC-7601 is most obviously improved, and the flexural modulus is also improved. Compared with Example 2, the overall strength of the product of Comparative Example 2 without PPA composition will decrease slightly, and it is found that the surface of the extruded particles is not very smooth and bright in the production process, the friction between the material and the cylinder wall is large in the extrusion process, causing defects on the surface of the particles. If it is applied to pipe processing, it can be clearly seen that the inner and outer walls of the pipe are not smooth, with cord-like lines, thereby reducing the mechanical strength. From the results, it can be seen that Example 2 has excellent impact resistance, heat resistance and toughness balance. Therefore, the complex nucleating agent JHC7601 is selected as the polypropylene β crystal complex nucleating agent in the subsequent test process, and industrial production is carried out.

[0069] Example 4

[0070] A polypropylene β crystal complex nucleating agent (Beijing Jihaihe River Complex Nucleating Agent JHC-7601) is composed of 17% Beijing Jihaihe River JHC-671, 30% antioxidant 1010, 20% antioxidant 330, 19% antioxidant 168, 8% calcium stearate and 6% polyphthalamide.

[0071] The difference between the production process of the β crystal homopolypropylene pipe special material and Example 1 is only that the polypropylene β crystal complex nucleating agent is replaced by the polypropylene β crystal complex nucleating agent of the present application, and the addition amount of the polypropylene β crystal complex nucleating agent in the homopolypropylene base powder is 7500 ppm.

[0072] Example 5

[0073] The same polypropylene β crystal complex nucleating agent as in Example 4 is used.

[0074] The difference between the production process of the β crystal homopolypropylene pipe special material and Example 3 is only that the addition amount of the polypropylene β crystal complex nucleating agent in the homopolypropylene base powder is 7000 ppm.

[0075] Example 6

[0076] The same polypropylene β crystal complex nucleating agent as in Example 4 is used.

[0077] The difference between the production process of the β crystal homopolypropylene pipe special material and Example 3 is only that the addition amount of the polypropylene β crystal complex nucleating agent in the homopolypropylene base powder is 6500 ppm.

[0078] Comparative Example 3

[0079] The polypropylene compounding aid in Comparative Example 1 is composed of 30% of antioxidant 1010, 20% of antioxidant 330, 19% of antioxidant 168, 8% of calcium stearate and 6% of polyphthalamide, without adding aromatic amide and rare earth type β crystal nucleating agent.

[0080] The production process of the β crystal type homopolypropylene pipe special material is different from that of Example 3 only in that the polypropylene β crystal type compounding nucleating agent is replaced by the polypropylene compounding aid in the comparative example, and the addition amount of the polypropylene compounding aid in the homopolypropylene base powder is 7500 ppm.

[0081] The homopolypropylene pipe special material in the above examples and comparative examples is injected into a test strip by a double screw injection molding machine, and the injection molding temperature is set to 210°C, 255°C, 255°C, 255°C and 220°C. The test strip is tested for melt index according to the national standard GB / T3682, for tensile strength according to the national standard GB / T 1040, for bending modulus according to the national standard GB / T 9341, for simply supported beam impact strength according to the national standard GB / T 1043, and for oxidation induction time according to the national standard GB / T 19466. The test results are shown in Table 2.

[0082] Table 2

[0083]

[0084] In the early stage of the project research, polypropylene powder with a melt index similar to that of the target product (H1022) is selected for small-scale formula test. It can be seen from the physical property data that the low temperature impact, bending modulus and oxidation induction time values of Example 4 (addition amount of 7500 ppm) are all better, so the addition amount of the polypropylene β crystal type compounding nucleating agent (JHC7601) in the first industrial production is 7500 ppm.

[0085] Example 7

[0086] The polypropylene β crystal type compounding nucleating agent with the same formula as Example 4 is composed of 17% of Beijing Jihai River JHC-671, 30% of antioxidant 1010, 20% of antioxidant 330, 19% of antioxidant 168, 8% of calcium stearate and 6% of polyphthalamide.

[0087] A β crystal type homopolypropylene pipe special material, the mass ratio of the polypropylene β crystal type compounding nucleating agent to the homopolypropylene is 1:132.

[0088] A production process of a β crystal type homopolypropylene pipe special material, comprising the following steps:

[0089] Step A: Precontacting reaction

[0090] The main catalyst DJD-2-B, the cocatalyst triethylaluminum and the external donor cyclohexyl methyl dimethoxysilane (Donor C) were mixed with the oil and fat into a precontacting tank, in which the main catalyst was activated by triethylaluminum (TEAL) to form the active center Ti-C bond. The precontacted catalyst and the oil and fat were mixed and reacted in the precontacting tank under the protection of nitrogen. The precontacting reaction temperature was 10-13°C, and the pressure was 3.5-3.6 MPa. The oil and fat component was a mixture of white oil and vaseline with a volume ratio of 2:1. The mass ratio of the cocatalyst to the main catalyst was 6.2%, the aluminum-to-propylene ratio was 0.18%, and the aluminum-to-silicon ratio was 7-8%.

[0091] Step B: Prepolymerization reaction

[0092] The catalyst and the oil and fat in the precontacting tank were subjected to a prepolymerization reaction with cold propylene passing through an online mixer. The prepolymerization was carried out in a propylene liquid phase bulk environment, and was carried out in a small loop pipe at a temperature of 15-21°C and a pressure of 3.4-4.5 MPa, with a residence time of 10-15 min.

[0093] Step C: Homopolymerization reaction

[0094] The prepolymerization product was subjected to a homopolymerization reaction in a liquid phase double loop pipe reactor under the action of the catalyst to obtain a homopolymerization polypropylene base powder.

[0095] The homopolymerization reaction conditions were as follows: a temperature of 69-71°C, a pressure of 3.4-4.5 MPa, and a residence time of 60-70 min. The amount of Atmer 163 additive added to the main reactor effluent was 1.5 kg / h.

[0096] Hydrogen was added to the double loop pipe reactor to adjust the molecular weight of the polymer. The hydrogen concentration in the first loop pipe of the liquid phase double loop pipe reactor was 210-230 ppm, and the hydrogen concentration in the second loop pipe was 0 ppm. The melt index of the homopolymerization polypropylene powder generated in the reactor was controlled to be 0.25-0.37 g / 10 min. The amount and type of the homopolymerization catalyst were the same as those of the precontacting reaction. The density of the homopolymerization polypropylene powder in the first loop pipe of the liquid phase double loop pipe reactor was 550 kg / m 3 , and the density of the homopolymerization polypropylene powder in the second loop pipe was 560 kg / m 3 .

[0097] Step D: Blending, extruding and granulating

[0098] The homopolypropylene base powder prepared in step C is transported to an extrusion granulation unit, and a polypropylene β crystal form complex nucleating agent is melt-extruded and granulated in a twin-screw extruder to obtain a β crystal form homopolypropylene pipe special material. The addition amount of the polypropylene β crystal form complex nucleating agent to the homopolypropylene base powder is 7500 ppm. The parameters of the twin-screw extruder are as follows: the temperature of each section from the feeding port to the die head is 190°C, 230°C, 230°C, 230°C, 230°C, 230°C, and 210°C, the main machine speed is 210 rpm, the melt pressure is 1.3 MPa, and the melt temperature is 225°C.

[0099] The β crystal form homopolypropylene pipe special material (H1022) with bimodal distribution of molecular weight is produced by using the above process, and the granules of the product (H1022) are detected before leaving the factory, and the detection data are shown in Table 3.

[0100] Table 3

[0101]

[0102] The H1022 industrial product produced by the polypropylene β crystal form complex nucleating agent and the Spheripol loop process can be seen from the above detection data. The physical property values of the H1022 product are obviously better than those of two commercial products (the β crystal form homopolypropylene materials of the commercial products 1 and 2 are BE60-7032 of Nordic Chemical and T1001J of Yanshan Petrochemical, respectively). The heat distortion temperature of the H1022 product produced by the present application is 113°C (national standard 95°C), and the temperature and pressure resistance is better than that of the market similar products. The downstream typical user feedback is that the pipe product has high gloss and excellent impact resistance, which meets the national standard of β-PPH pipe. The product can be used as process pipeline and pipe in new energy field chemical production.

[0103] Example 8

[0104] The H1022 product is produced three times, and the basic physical property values meet the technical index requirements and are stable in performance. However, the room temperature impact surplus of the product is large, and the bending value has a lot of room for improvement. The optimization and adjustment target of the product is to reduce toughness and increase rigidity, and at the same time, to reduce cost and increase efficiency. Therefore, the polypropylene β crystal form complex nucleating agent is further optimized and evaluated in a small test, and the effect of the addition amount of the polypropylene β crystal form complex nucleating agent (JHC7601) on the performance is evaluated, and the performance detection data are shown in Table 4.

[0105] Table 4

[0106]

[0107] From the above table property data: the amount of complex nucleating agent is reduced from 6500 to 6000ppm, the tensile bending performance is slightly improved, the room temperature impact strength is greatly reduced to 93KJ / m 2 (The national standard is greater than 50), the oxidation induction period exceeds the national standard of 20min, which meets the adjustment expectation and provides data support for the subsequent product scale production.

[0108] Obviously, the above embodiments of the present application are only examples for clearly illustrating the present application, and are not intended to limit the embodiments of the present application. For those skilled in the art, other different forms of changes or variations can be made on the basis of the above description, and it is impossible to enumerate all the embodiments here. Any obvious changes or variations derived from the technical solutions of the present application still fall within the protection scope of the present application.

Claims

1. A polypropylene β-crystal form compounding nucleating agent, characterized in that, The polypropylene β crystal nucleating agent comprises, by weight, 15-20% of a β crystal nucleating agent, 60-70% of an antioxidant, 7-11% of calcium stearate, and 5-10% of polyphthalamide.

2. The polypropylene β-crystal form compounding nucleating agent according to claim 1, characterized in that, The β crystal nucleating agent is selected from a rare earth β crystal nucleating agent and / or an aromatic amide β crystal nucleating agent.

3. The polypropylene β-crystal form compounding nucleating agent according to claim 1, characterized in that, The antioxidant is selected from a hindered phenol antioxidant and / or a phosphite antioxidant.

4. A speciality grade for β crystalline form homopolypropylene pipe material, characterized by, The polypropylene β crystal nucleating agent and the homopolymer polypropylene are as claimed in any one of claims 1-3.

5. The β crystalline homopolypropylene pipe specialty resin according to claim 4, characterized in that, The mass ratio of the polypropylene β crystal nucleating agent to the homopolymer polypropylene is 1:120-170.

6. A process for the production of a β-crystalline homopolypropylene pipe speciality according to claim 4 or 5, characterized in that, The method comprises the following steps: The homopolymer polypropylene is blended with the polypropylene β crystal nucleating agent as claimed in any one of claims 1-3, and sequentially subjected to melting, extrusion, and granulation to obtain the β crystal homopolymer polypropylene pipe material.

7. The process for producing a β crystalline form homopolypropylene pipe specialty resin according to claim 6, characterized in that, The addition amount of the polypropylene β crystal nucleating agent is 5500-8000 ppm.

8. The process for producing a β crystalline form homopolypropylene pipe special material according to claim 6, characterized in that, The homopolymer polypropylene is prepared in the following manner: In step S1, the pre-polymerization reaction is carried out at a pre-polymerization temperature of 15-21°C, a pressure of 3.4-4.5 MPa, and for 10-15 min. Preferably, in step S2, the homopolymerization reaction is carried out at a homopolymerization temperature of 69-71°C, a pressure of 3.4-4.5 MPa, and for 60-70 min.

9. The process for producing a β crystalline form homopolypropylene pipe specialty resin according to claim 8, characterized in that, ​ 10. The process for producing a β crystalline form homopolypropylene pipe specialty resin according to claim 8, characterized in that, ​ ​

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