Polypropylene beta nucleating agent as well as preparation method and application thereof

Abstract

The invention discloses a polypropylene beta nucleating agent and a preparation method and application thereof, and belongs to the technical field of polypropylene nucleating agents, the provided amide-structure POCs polypropylene beta nucleating agent can significantly improve the crystallization selectivity and crystallization efficiency of PP, can induce PP to generate high-content beta crystals, improves the mechanical property of PP at the same time, and has good application prospects. The toughness of the PP is improved, and meanwhile, the high-level rigidity is kept. The POCs polypropylene beta nucleating agent with the amide structure is the first application of the POCs structure in the field of the polypropylene beta nucleating agent, and the application range of the POCs and the optional range of the polypropylene beta nucleating agent are widened. Compared with a micromolecular polypropylene nucleating agent, the POCs polypropylene beta nucleating agent with the amide structure is not easy to separate out in the subsequent PP use process, and pollution is avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of polypropylene nucleating agents, and specifically relates to a polypropylene β-nucleating agent, its preparation method and application. Background Art

[0002] Polypropylene (PP) is an important general-purpose plastic with advantages such as low density, strong chemical corrosion resistance, and excellent processing performance. It has been widely used in many fields such as packaging, automobiles, household appliances, and construction. Its good comprehensive performance makes it the second-largest general-purpose plastic in the world, second only to polyethylene. However, the toughness of pure polypropylene polymers is insufficient, especially showing high brittleness under low-temperature conditions, which limits its application in some high-performance fields. Therefore, modifying polypropylene to improve its toughness has always been a research hotspot in the field of materials science.

[0003] In order to improve the toughness of polypropylene, β-nucleating agents are currently mainly used for modification. β-nucleating agents induce polypropylene to form a specific β-crystalline structure. This crystalline form has a lower density and higher toughness, so it has been widely studied and applied. Common β-nucleating agents are divided into two categories: organic nucleating agents and inorganic nucleating agents. Inorganic β-nucleating agents mainly include inorganic salts and oxides such as calcium carbonate, calcium sulfate, and yttrium oxide. These nucleating agents are inexpensive, but have low nucleation efficiency and poor dispersibility in PP, which will affect the transparency of the material. Organic β-nucleating agents include polycyclic compound nucleating agents, organic acid nucleating agents, aromatic amide nucleating agents, etc. For example, CN102344388B provides a preparation method and application of an amide polypropylene β-nucleating agent, namely N,N'-dicyclohexyl-1,5-diamino-2,6-naphthalenedicarboxamide. Patent CN109401060B discloses a method for fine-tuning the shape and size of aromatic amide nucleating agents. CN85100465 and CN101605749A, etc. disclose a series of binary carboxylic acid β-nucleating agents composed of salts of binary carboxylic acids and Group IIA metal elements. However, while most existing β-nucleating agents improve the toughness of polypropylene, they often damage its rigidity, resulting in a decrease in the flexural modulus of the material, and many β-nucleating agents have poor processability, which limits the improvement and expansion of their functions. In addition, some small-molecule β-nucleating agents are prone to precipitation during the use of polypropylene, affecting the stability and long-term performance of the material and causing pollution. Therefore, it is of great practical significance to develop a new type of β-nucleating agent with good crystallization selectivity, high efficiency, stability and little impact on the rigidity of polypropylene.

[0004] In recent years, Porous Organic Cages (POCs), as a new type of low-density crystalline material, have received extensive attention due to their unique molecular structure and excellent pore properties. POCs have a high specific surface area and adjustable pore sizes. Their molecular weight is significantly larger than that of common small molecules, yet they have good solubility and processability. These characteristics endow them with great application potential in the fields of gas adsorption, molecular recognition, and catalysis. The cage-like structure and solution dispersibility of POCs make them less likely to precipitate during the processing of polypropylene, thereby improving the long-term stability of the material. Despite the many advantages of POCs in the field of materials science, although some POC materials have an amide structure similar to that of nucleating agents, there has been no report on the use of POCs as polypropylene nucleating agents. Summary of the Invention

[0005] The object of the present invention is to provide a polypropylene β-nucleating agent, its preparation method and application in order to solve the above-mentioned problems.

[0006] The technical solution adopted by the present invention is as follows: A polypropylene β-nucleating agent, characterized in that the structural formula of the amide-structured porous organic cage is as follows:

[0007]

[0008] Wherein R1, R2, R3, R4, and R5 are each independently one or more of -H, -CH3, -OH, -OCH3, -OCH2CH3, -O(CH2CH3O) n CH3, -NH2, etc., and n is a positive integer.

[0009] In a preferred embodiment, the amino precursor molecule is trimethyltrimethylamine-substituted benzene, preferably benzene-1,3,5-trimethyltrimethylamine (CAS 77372-56-6).

[0010] In a preferred embodiment, the carbonyl precursor molecule of the amide-structured porous organic cage is one of the following structures or a mixture of two or more of them:

[0011]

[0012] In a preferred embodiment, a preparation method of a polypropylene β-nucleating agent includes the following steps.

[0013] Step 1: Dissolve the carbonyl precursor molecule in methanol, add a catalyst, and heat under reflux to obtain an esterification product.

[0014] After purification, a pale yellow solid product IP-1 is obtained.

[0015] Step 2: Dissolve IP-1 in dichloromethane, add benzene-1,3,5-trimethyltrimethylamine, and heat and stir until no new product is generated. Cool and allow to stand, then separate and dry to obtain the target product, POCs.

[0016] In a preferred embodiment, the molar ratio of IP-1 to benzene-1,3,5-trimethyltrimethylamine is 3:2.

[0017] In a preferred embodiment, the catalyst used for esterification in step 1 is boron trifluoride etherate or sulfuric acid.

[0018] In a preferred embodiment, the reaction temperature in step 2 is reflux.

[0019] In a preferred embodiment, the polypropylene β-nucleating agent is used as an amide structure porous organic cage to modify polypropylene.

[0020] In a preferred embodiment, the amount of the polypropylene β-nucleating agent is 0.001 to 1% of the mass of the polypropylene.

[0021] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0022] 1. The amide structure POCs polypropylene β-nucleating agent provided in the present invention can significantly improve the crystallization selectivity and crystallization efficiency of PP, can induce PP to produce a high content of β crystals, and at the same time improve the mechanical properties of PP, while improving the toughness of PP while maintaining a high level of rigidity.

[0023] 2. The amide-structured POCs polypropylene β-nucleating agent described in this invention represents the first application of POCs in the field of polypropylene β-nucleating agents, broadening the application scope of POCs and the range of available polypropylene nucleating agents. Compared to small-molecule polypropylene nucleating agents, the amide-structured POCs polypropylene β-nucleating agent is less likely to precipitate during subsequent PP use, thus preventing contamination. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a crystal morphology diagram of the PP material prepared in Control Example 1 without using amide structure POCs as β-nucleating agents.

[0025] Figure 2 This is a crystal morphology diagram of the PP composite material prepared in Example 2 using amide structure POCs as β nucleating agent (0.01wt%).

[0026] Figure 3 This is a crystal morphology diagram of the PP composite material prepared in Example 4 using amide structure POCs as β-nucleating agents (0.2 wt%). DETAILED DESCRIPTION

[0027] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0028] Refer to Figures 1-3 ,

[0029] Example 1:

[0030] A preparation method of a polypropylene β-nucleating agent includes the following steps:

[0031] The first step is esterification: Dissolve 10 g of 2,3-dihydroxyterephthalic acid in 250 ml of methanol. Under a nitrogen atmosphere, add 15 ml of boron trifluoride diethyl ether solution to the mixture. Stir the mixed solution and reflux for 10 hours. Then, filter and dry the reaction solution to obtain a crude product. After purification, the esterification product IP-1-1 is obtained.

[0032]

[0033] The second step is aminolysis. Dissolve 2.00 g of the esterification product IP-1-1 in 500 ml of dichloromethane solution. Add 0.97 g of benzene-1,3,5-trimethyltrimethylamine. Stir the reaction mixture at room temperature for 4 hours and then reflux for 12 hours. After the reaction is completed, cool, let stand, filter and dry to obtain the target product, the polypropylene β-nucleating agent POC-1. Silica gel column chromatography separation can be further used for purification. H-NMR(CD3CI, ppm): 4.45(d, 12H, -CH2), 7.47(s, 6H, Ar-H), 7.93(s, 6H, Ar-H), 7.83(t, NH).

[0034]

[0035] Example 2:

[0036] A preparation method of a polypropylene β-nucleating agent includes the following steps:

[0037] The first step is esterification: Dissolve 10 g of 2,3-dihydroxyterephthalic acid in 250 ml of methanol. Add 5 ml of concentrated sulfuric acid to the mixture. React and reflux the mixed solution at 65 °C overnight. Then, filter, wash and dry the reaction solution to obtain a crude product. After purification, the intermediate product IP-1-1 is obtained.

[0038]

[0039] The first step is etherification: Dissolve 5 g of IP-1-1 in 200 ml of DMF, add an excess of bromomethane and dry anhydrous potassium carbonate, heat to 85 °C and stir the reaction for 5 hours. Pour the product into hot water, extract with ethyl acetate, and obtain the intermediate product IP-1-1 after drying.

[0040]

[0041] The third step is aminolysis. Dissolve 2.00 g of the esterification product IP-1-2 in 500 ml of dichloromethane solution, add 0.87 g of 1,3,5-trimethylbenzyltrimethylammonium, stir the reaction mixture at room temperature for 4 hours, and then reflux for 12 hours. After the reaction is completed, cool and let stand, filter and dry to obtain the target product polypropylene β-nucleating agent POC-2. Column chromatography on silica gel can be used for further purification. H-NMR(CD3CI, ppm): 3.91(s, 18H, -OCH3), 4.46(d, 12H, -CH2), 7.47(s, 6H, Ar-H), 7.93(s, 6H, Ar-H), 8.23(t, NH).

[0042]

[0043] Example 3: Amide structure POCs are used as polypropylene β-nucleating agents for modifying polypropylene.

[0044] (1) Melt-blend 0.01 g of the amide structure POC-1 prepared in Example 1 with 1 kg of PP pellets (T30S, the mass fraction of the amide structure is 0.001%) in a twin-screw extruder to prepare a modified polypropylene material.

[0045] (2) Conduct a crystal form test on the modified polypropylene. Take an appropriate amount of the polypropylene sample obtained by torque and press it into a thin sheet of about 0.5 mm on a precision automatic tablet press, and perform XRD testing with an X-ray diffractometer X’PertProMPDDY1291 to measure its β-crystal content K β , and the test results are shown in Table 1.

[0046] (3) Conduct physical property tests on the modified polypropylene, respectively according to national standards: the notched izod impact strength complies with the standard GB / T1843-1996, and the flexural property complies with the standard GB / T9341-2000. The test results are listed in Table 1.

[0047] Control Example 1: Polypropylene without adding amide structure POCs, and the performance test is the same as that of Example 2.

[0048] Example 4: Prepare modified polypropylene with the mass fraction of amide structure POCs being 0.01%, and the other processing conditions, steps and performance tests are the same as those in Example 2.

[0049] Example 5: Modified polypropylene was prepared with the mass fraction of amide - structured POCs being 0.2%. Other processing conditions, steps, and performance tests were the same as those in Example 2.

[0050] Example 6: Modified polypropylene was prepared with the mass fraction of amide - structured POCs being 1%. Other processing conditions, steps, and performance tests were the same as those in Example 2.

[0051] Table 1. β - crystal content, impact strength, and flexural modulus of polypropylene before and after being modified by nucleating agents with different contents of amide - structured POCs

[0052]

[0053] As can be seen from Table 1, the impact strength of polypropylene modified by the amide - structured POCs polypropylene β - nucleating agent has been significantly improved. Among them, when the nucleating agent dosage is 0.01%, the impact strength increases to more than 300% of the original polypropylene. It is worth noting that in the case of a significant increase in impact strength, this nucleating agent overcomes the problem of the decrease in the flexural modulus of polypropylene caused by general β - crystal nucleating agents, and greatly improves the mechanical properties of polypropylene.

[0054] It can be known from the above that:

[0055] In the present invention, the provided amide - structured POCs polypropylene β - nucleating agent can significantly improve the crystallization selectivity and crystallization efficiency of PP, can induce PP to generate a high content of β - crystals, and at the same time improve the mechanical properties of PP, maintaining a relatively high level of rigidity while improving the toughness of PP.

[0056] In the present invention, the amide - structured POCs polypropylene β - nucleating agent is the first application of the POCs structure in the field of polypropylene β - nucleating agents, broadening the application scope of POCs and the optional range of polypropylene nucleating agents. Compared with small - molecule polypropylene nucleating agents, the amide - structured POCs polypropylene β - nucleating agent is not easily precipitated during the subsequent use of PP, avoiding pollution.

[0057] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article, or device comprising the said element.

[0058] The foregoing description enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A polypropylene β-nucleating agent, characterized in that, The structural formula of the amide-structured porous organic cage is as follows: wherein R1, R2, R3, R4, and R5 are each independently one or more of -H, -CH3, -OH, -OCH3, -OCH2CH3, -O(CH2CH3O) n CH3, -NH2, etc., and n is a positive integer.

2. The polypropylene β-nucleating agent according to claim 1, characterized in that: The amino precursor molecule is trimethyl trimethylamine-substituted benzene, preferably benzene-1,3,5-trimethyl trimethylamine (CAS 77372-56-6).

3. The POC molecule according to claim 1, wherein The carbonyl precursor molecule is one of the following structures or a mixture of two or more of them:

4. The preparation method of a polypropylene β nucleating agent according to claim 1, characterized in that: It includes the following steps: Step 1: Dissolve the carbonyl precursor molecule in methanol, add a catalyst, heat under reflux to obtain an esterification product, and obtain a pale yellow solid product IP-1 after purification; Step 2: Dissolve IP-1 in dichloromethane, add benzene-1,3,5-trimethyl trimethylamine, heat and stir the reaction until no new product is formed; cool and let stand, separate and dry to obtain the target product POCs.

5. The preparation method of a polypropylene β nucleating agent according to claim 1, characterized in that, The molar ratio of IP-1 to benzene-1,3,5-trimethyl trimethylamine is 3:

2.

6. The preparation method of the amide structure porous organic cage according to claim 4, wherein, The catalyst used for esterification in Step 1 is boron trifluoride diethyl ether or sulfuric acid.

7. The preparation method of the amide-structured porous organic cage according to claim 4, wherein, The reaction temperature in Step 2 is reflux.

8. Use of a polypropylene β-nucleating agent, characterized in that: The polypropylene β-nucleating agent is used as an amide-structured porous organic cage in the modification of polypropylene.

9. The application of the polypropylene β-nucleating agent according to claim 8, wherein: The dosage of the polypropylene β-nucleating agent is 0.001-1% of the mass of polypropylene.

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