A micro-foamed polypropylene material and its preparation method and application

Abstract

The present invention relates to a microcellular polypropylene material, a preparation method thereof and an application. The components of the microcellular polypropylene material include: polypropylene resin, compatibilizer, filler, toughening agent and additive. After foaming, the microcellular polypropylene material has a high closed-cell ratio, a weight reduction ratio and can maintain good notched impact strength.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and more specifically, to a micro-foamed polypropylene material and a preparation method and application thereof. Background Art

[0002] Lightweighting is a development trend in the automotive industry, and foaming has become one of the important ways to achieve lightweighting. Among them, polypropylene micro-foaming is favored by automobile manufacturers, and in-depth research and exploration are carried out on interior and exterior trims. For example, the application of foaming materials in components such as instrument panels, door panels, inner door handles, and seat guide guards will bring major breakthroughs.

[0003] EPP stands for expanded polypropylene, which is produced by foaming and modifying polypropylene. It has the characteristics of high hardness, light weight and energy absorption, and is widely used in the automotive industry. EPP is a highly crystalline composite material with excellent performance. With its unique and superior performance, it has become the fastest growing and most environmentally friendly pressure-resistant buffering and heat-insulating material. For EPP, the main focus is on the weight loss ratio and closed-cell rate after foaming. The higher the weight loss ratio and the higher the closed-cell rate, the better the foaming performance. Among them, a high weight loss ratio can effectively reduce the material cost of the company's production. In addition, since EPP is often used to prepare pressure-resistant and buffering components, it is also required to have good impact strength.

[0004] The Chinese patent with patent number CN110791015A adds a melt strength regulator (0.1 to 5 g / 10 min of ethylene-octene copolymer) and a solvent resistance improver (2 to 50 g / 10 min of ethylene-octene copolymer) to injection-molding grade polypropylene material, but it can only reflect the closed cell rate and does not focus on weight reduction effect and impact strength.

[0005] In order to solve the above problems, it is necessary to develop a foamed polypropylene with high closed cell rate, high weight reduction ratio and good impact strength. Summary of the invention

[0006] The primary purpose of the present invention is to overcome the problems of poor closed cell rate and weight loss ratio of foamed polypropylene in the above-mentioned prior art and insufficient attention to the impact strength of foamed polypropylene, and to provide a micro-foamed polypropylene material. The micro-foamed polypropylene material has a high closed cell rate and weight loss ratio after foaming and can maintain good notched impact strength.

[0007] A further object of the present invention is to provide a method for preparing the above-mentioned micro-foamed polypropylene material.

[0008] A further object of the present invention is to provide the use of the above-mentioned micro-foamed polypropylene material in the preparation of automobile pressure-resistant and buffering parts.

[0009] The above-mentioned object of the present invention is achieved by the following technical solutions:

[0010] A micro-foamed polypropylene material, comprising the following groups in parts by weight:

[0011]

[0012] The melt index of the polypropylene resin is 0.5 to 3 g / 10 min;

[0013] The compatibilizer is ethylene-propylene-butylene terpolymer polypropylene grafted with sodium maleate, and the grafting rate is 1.5-3%.

[0014] In the present invention, the grafting rate of sodium maleate grafted onto polypropylene of ethylene, propylene and butylene terpolymer refers to the mass fraction of sodium maleate in the sodium maleate grafted onto polypropylene of ethylene, propylene and butylene terpolymer, which is measured by acid-base titration.

[0015] In the present invention, the melt index of the polypropylene resin can be measured according to the test standard ISO 1133-1 / 2:2012 under the test conditions of 230° C. and 2.16 kg.

[0016] The inventor of the present invention has found through research that the micro-foamed polypropylene material obtained by selecting a polypropylene resin with a specific melt index and a specific compatibilizer (a specific grafting rate of ethylene, propylene and butyl terpolymer polypropylene grafted with sodium maleate) has a high closed cell rate and weight loss ratio after foaming. The reason is that the specific grafting rate of ethylene, propylene and butyl terpolymer polypropylene grafted with sodium maleate can give the polypropylene resin with a specific melt index a strong bonding force with the filler interface, significantly improve the melt strength of the material, and facilitate the foaming molding of the material, thereby significantly improving the closed cell rate and weight loss ratio of the micro-foamed polypropylene material. In addition, by adding a specific compatibilizer, the notched impact strength of the micro-foamed polypropylene material after foaming can also be significantly improved, so that the micro-foamed polypropylene material maintains good notched impact strength after foaming. Specifically, the weight loss ratio of the micro-foamed polypropylene material after foaming can reach more than 29.7%, and the highest can reach 38.1%; the closed cell rate can reach more than 94.7%, and the highest can reach 98.8%; the cantilever beam notched impact strength can be maintained at 28.9KJ / m 2 The above can meet the requirements of application scenarios, and the maximum can reach 49.7KJ / m 2 .

[0017] That is, the micro-foamed polypropylene material of the present invention has a high closed cell rate and weight reduction ratio after foaming and can maintain good notched impact strength.

[0018] Preferably, the micro-foamed polypropylene material comprises the following groups in parts by weight:

[0019]

[0020]

[0021] Preferably, the grafting rate of the ethylene-propylene-butylene terpolymer polypropylene grafted with sodium maleate is 1.6-2.8%.

[0022] Preferably, the ethylene-propylene-butadiene ternary copolymer polypropylene grafted with sodium maleate is prepared by the following method: mixing ethylene-propylene-butadiene ternary copolymer polypropylene, sodium maleate and an antioxidant to obtain a mixture for use; dissolving an initiator, α-methylstyrene and 1-octene in a solvent to obtain a mixed solution for use; adding the mixed solution to the mixture, and melt-extruding to obtain the ethylene-propylene-butadiene ternary copolymer polypropylene grafted with sodium maleate.

[0023] Optionally, the melt index of the ethylene-propylene-butylene terpolymer polypropylene in the ethylene-propylene-butylene terpolymer polypropylene grafted with sodium maleate is 5 to 9 g / 10 min.

[0024] Preferably, the melt index of the ethylene-propylene-butadiene terpolymer polypropylene in the ethylene-propylene-butadiene terpolymer polypropylene grafted with sodium maleate is 7 to 9 g / 10 min.

[0025] The melt index of ethylene-propylene-butadiene terpolymer polypropylene in ethylene-propylene-butadiene terpolymer polypropylene grafted with sodium maleate is within this range, and the obtained micro-foamed polypropylene material has higher closed cell rate, weight reduction ratio and notched impact strength.

[0026] The melt index of ethylene-propylene-butadiene terpolymer polypropylene can be measured under the test conditions of 230°C and 2.16kg according to the test standard ISO 1133-1 / 2:2012.

[0027] More preferably, the antioxidant is antioxidant 1010, antioxidant 168 or antioxidant DSTDP.

[0028] More preferably, the initiator is di-tert-butyl peroxide.

[0029] More preferably, the amounts of the components used in the preparation process of the ethylene-propylene-butadiene terpolymer polypropylene grafted with sodium maleate are: 100 parts by weight of ethylene-propylene-butadiene terpolymer polypropylene, 2 to 4 parts by weight of sodium maleate, 0.2 to 0.4 parts by weight of antioxidant, 0.2 to 0.4 parts by weight of initiator, 2 to 3 parts by weight of α-methylstyrene, and 1 to 1.5 parts by weight of 1-octene.

[0030] More preferably, after the melt extrusion, a purification step is also included.

[0031] Specifically, the ethylene-propylene-butylene terpolymer polypropylene grafted sodium maleate is prepared by the following method (the unit of the amount of each component is part by weight):

[0032] a) mixing 100 parts of ethylene-propylene-butane terpolymer polypropylene, 2-4 parts of sodium maleate, and 0.2-0.4 parts of antioxidant uniformly by a high-speed mixer at a speed of 650-750 RPM to obtain a mixture for standby use;

[0033] b) dissolving 0.2-0.4 parts of initiator di-tert-butyl peroxide (DTBP), 2-3 parts of α-methylstyrene (AMS), and 1-1.5 parts of 1-octene in 35-45 parts of acetone at 35-45° C. to obtain a mixed solution for standby use;

[0034] c) adding the above mixed solution to the mixture of step a), mixing evenly in a high-speed mixer, adding the mixture to a twin-screw extruder for melt extrusion grafting reaction after all the acetone is volatilized, and obtaining a crude product of ethylene-propylene-butylene terpolymer polypropylene grafted with sodium maleate; wherein the temperature of the twin-screw extruder is 135-150° C.;

[0035] d) Take 1 part of the crude product of ethylene-propylene-butadiene terpolymer polypropylene grafted with sodium maleate, add it to 35-45 parts of xylene, stir at 70-80°C until it is completely dissolved, then pour it into 60-70 parts of acetone solution while hot to form a flocculent precipitate product, then rinse it with acetone 3-5 times to obtain the first purified product, and then put the flocculent precipitate into a fume hood and dry it to constant weight; repeat the above purification twice, and finally obtain the purified ethylene-propylene-butadiene terpolymer polypropylene grafted with sodium maleate, put it into a vacuum drying oven and dry it for 24 hours to constant weight for use.

[0036] The fillers and toughening agents commonly used in the art can be used in the present invention without special limitation.

[0037] Optionally, the filler includes but is not limited to talc, calcium carbonate or basic magnesium sulfate whisker.

[0038] Optionally, the toughening agent includes but is not limited to ethylene-octene random copolymer, ethylene-butene random copolymer, metallocene linear low density polyethylene (MLLDPE), metallocene ethylene-propylene copolymer or hydrogenated styrene-butadiene-styrene linear triblock copolymer (SEBS) and the like.

[0039] Preferably, the toughening agent is at least one of ethylene-butene random copolymer or metallocene linear low-density polyethylene.

[0040] The toughening agent is selected from ethylene-butene random copolymer or metallocene linear low-density polyethylene, and the micro-foamed polypropylene material has a higher closed cell rate and weight reduction ratio after foaming.

[0041] Preferably, the toughening agent is a hydrogenated styrene-butadiene-styrene linear triblock copolymer.

[0042] The toughening agent is hydrogenated styrene-butadiene-styrene linear triblock copolymer, and the obtained micro-foamed polypropylene material has a high closed cell rate and a high weight loss ratio, and also has a higher notched impact strength. In addition, since the hydrogenated styrene-butadiene-styrene linear triblock copolymer has been hydrogenated, the weather resistance is outstanding, which makes the micro-foamed polypropylene material have better weather resistance and a good low-temperature toughening effect.

[0043] Optionally, the auxiliary agent is at least one of an antioxidant or a lubricant.

[0044] Optionally, the antioxidant includes but is not limited to hindered phenols or phosphites.

[0045] Optionally, the lubricant includes but is not limited to stearate lubricants.

[0046] The method for preparing the micro-foamed polypropylene material comprises the following steps: mixing the components, melt-extruding, and granulating to obtain the micro-foamed polypropylene material.

[0047] Preferably, the melt extrusion is performed using a twin-screw extruder.

[0048] More preferably, the temperature of the twin-screw extruder is 170-200°C.

[0049] The application of the above-mentioned micro-foamed polypropylene material in the preparation of automobile pressure-resistant and buffering parts is also within the protection scope of the present invention.

[0050] Preferably, the automobile pressure-resistant and buffering component is a side guard plate of an automobile seat.

[0051] Compared with the prior art, the present invention has the following beneficial effects:

[0052] The micro-foamed polypropylene material of the invention has a high closed cell rate and weight reduction ratio after foaming and can maintain good notched impact strength. DETAILED DESCRIPTION

[0053] In order to more clearly and completely describe the technical solution of the present invention, the present invention is further described in detail through specific embodiments below. 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. Various changes can be made within the scope of the rights of the present invention.

[0054] Some of the reagents selected in the embodiments and comparative examples of the present invention are described as follows:

[0055] Polypropylene resin 1#: B8101 (copolymer, MFR=0.5g / 10min), Yanshan Petrochemical;

[0056] Polypropylene resin 2#: AS164 (copolymer, MFR=1.2 g / 10 min), Singapore TPC;

[0057] Polypropylene resin 3#: K8303 (copolymer, MFR=3g / 10min), Yanshan Petrochemical;

[0058] Polypropylene resin 4#: B1101 (homopolymer, MFR = 0.5g / 10min), Taiwan Chemical Fiber from Taiwan, my country;

[0059] Polypropylene resin 5#: EP548R (copolymer, MFR=30g / 10min), CNOOC Shell;

[0060] Filler 1#: talcum powder, AH-51210 (3000 mesh talcum powder), Liaoning Aihai;

[0061] Filler 2#: whisker, WS-1S2 (basic magnesium sulfate whisker), Yingkou Kangru Technology;

[0062] Filler 3#: calcium carbonate, 75T, Changxing Omiya;

[0063] Toughener 1#: MFR = 0.5 g / 10 min (190°C / 2.16 kg), ethylene-octene random copolymer, 8150, Dow Chemical, USA;

[0064] Toughener 2#: MFR = 0.3 g / 10 min (190°C / 2.16 kg), ethylene-butene random copolymer, DF605, Mitsui Chemicals, Japan;

[0065] Toughener 3#: MFR = 13 g / 10 min (190°C / 2.16 kg), hydrogenated styrene-butadiene-styrene linear triblock copolymer (SEBS), model G1657, Kraton, USA;

[0066] Toughener 4#: MFR = 1.5 g / 10 min (190°C / 2.16 kg), metallocene ethylene-propylene copolymer, Vistamaxx 6102, ExxonMobil;

[0067] Toughener 5#: MFR = 1.0 g / 10 min (190°C / 2.16 kg), metallocene linear low-density polyethylene (MLLDPE), EXCEED 1018MF, ExxonMobil;

[0068] The melt index of the above toughening agent can be measured according to the test standard ISO 1133-1 / 2:2012 under the test conditions of 190° C. and 2.16 kg.

[0069] EPDM terpolymer polypropylene 1#: F5006, MFR=6.0g / 10min (230℃ / 2.16kg), Yanshan Petrochemical;

[0070] Ethylene-propylene-butadiene terpolymer polypropylene 2#: C5608M, MFR=8.0g / 10min (230℃ / 2.16kg), Yanshan Petrochemical;

[0071] Poly 1-butene: 509, MFR = 5.5 g / 10 min (230 ° C / 2.16 kg), LyondellBasell;

[0072] Compatibilizer 1#: Homemade, the preparation method is as follows (the unit of the amount of each component is weight part):

[0073] a) mixing 100 parts of ethylene-propylene-butane terpolymer polypropylene 1#, 2.0 parts of sodium maleate, and 0.22 parts of antioxidant uniformly by a high-speed mixer at a speed of 670 RPM to obtain a mixture for standby use;

[0074] b) dissolving 0.22 parts of initiator di-tert-butyl peroxide (DTBP), 2 parts of α-methylstyrene (AMS), and 1.1 parts of 1-octene in 36 parts of acetone at 36° C. to obtain a mixed solution for later use;

[0075] c) adding the above mixed solution to the mixture of step a), mixing evenly in a high-speed mixer, adding the mixture to a twin-screw extruder for melt extrusion grafting reaction after all the acetone is volatilized, and obtaining a crude product of ethylene-propylene-butylene terpolymer polypropylene grafted with sodium maleate; wherein the temperature of the twin-screw extruder is 136° C.;

[0076] d) Take 1 part of the crude product of ethylene-propylene-butadiene terpolymer polypropylene grafted with sodium maleate and add it to 35 parts of xylene and stir at 72°C until it is completely dissolved, then pour it into 62 parts of acetone solution while hot to generate flocculent precipitation product, then rinse it with acetone for 3 times to obtain the first purified product, then put the flocculent precipitation into a fume hood and dry it to constant weight; repeat the above purification for 2 times, and finally obtain the purified ethylene-propylene-butadiene terpolymer polypropylene grafted with sodium maleate and put it into a vacuum drying oven to dry for 24 hours to constant weight, that is, to obtain compatibilizer 1#. The grafting rate of compatibilizer 1# is 1.6%.

[0077] Compatibilizer 2#: Homemade, the preparation method is basically the same as that of compatibilizer 1#, except that the amount of sodium maleate used is 3.0 parts. The grafting rate of compatibilizer 2# is 2.2%.

[0078] Compatibilizer 3#: self-made, the preparation method is basically the same as that of compatibilizer 1#, except that ethylene-propylene-butadiene terpolymer polypropylene 1# is replaced by ethylene-propylene-butadiene terpolymer polypropylene 2#. The grafting rate of compatibilizer 3# is 2.8%.

[0079] Compatibilizer 4#: Homemade, the preparation method is basically the same as that of compatibilizer 1#, except that the amount of sodium maleate used is 1.5 parts. The grafting rate of compatibilizer 4# is 0.8%.

[0080] Compatibilizer 5#: Homemade, the preparation method is basically the same as that of compatibilizer 1#, except that ethylene-propylene-butene terpolymer propylene 1# is replaced with poly-1-butene to obtain poly-1-butene grafted with sodium maleate. The grafting rate of compatibilizer 5# is 1.1%.

[0081] Antioxidant 1#: SONOX 1010, commercially available;

[0082] Antioxidant 2#: SONOX 168, commercially available;

[0083] Lubricant: zinc stearate, commercially available;

[0084] Foaming agent: sodium bicarbonate masterbatch, EE25C, Japan Yonghe.

[0085] Unless otherwise specified, the components (such as antioxidants, lubricants, etc.) selected in the parallel examples and comparative examples are all the same commercially available products.

[0086] The preparation process of the micro-foamed polypropylene material of each embodiment of the present invention and the comparative example is as follows: After weighing each component according to the ratio, add it to a high mixer and stir and blend it at a speed of 650 rpm for 4 minutes to obtain a premix, add the mixed particles into a 75D co-rotating twin-screw extruder for melt extrusion, granulation, drying, and cooling to obtain a micro-foamed polypropylene material. The temperature of the twin-screw extruder is 170°C, 200°C, 200°C, 210°C, 210°C, 205°C, 205°C, 205°C, 200°C, and 200°C from the feeding section to the die.

[0087] 100 parts by weight of micro-foamed polypropylene material was mixed evenly with 2 parts by weight of a foaming agent, added into an injection molding machine for foaming, and injection molded into test specimens for performance testing.

[0088] The micro-foamed polypropylene materials provided in the embodiments and comparative examples of the present invention are foamed and injection molded into test specimens and the performance is measured according to the following test method:

[0089] Density: Tested in accordance with ISO 1183-1-2019; unit: g / cm 3 ;

[0090] Weight reduction ratio: [(density before foaming - density after foaming) / density before foaming]*100%;

[0091] Cell closed cell ratio: tested in accordance with GB 10799-2008;

[0092] Izod notched impact strength: tested according to ISO 180-2000; unit: KJ / m 2 ;

[0093] Examples 1 to 14

[0094] Examples 1 to 14 provide a series of micro-foamed polypropylene materials, whose formulations are shown in Tables 1 and 2.

[0095] Table 1 Formulas of Examples 1 to 8 (parts by weight)

[0096]

[0097]

[0098] Table 2 Formulas of Examples 9 to 14 (parts by weight)

[0099]

[0100] Comparative Example 1

[0101] This comparative example provides a micro-foamed polypropylene material, and its formula is different from that of Example 1 in that 50 parts of polypropylene resin 5# are added instead of polypropylene resin 1# and polypropylene resin 2#.

[0102] Comparative Example 2

[0103] This comparative example provides a micro-foamed polypropylene material, the formula of which is different from that of Example 1 in that compatibilizer 1# is replaced by compatibilizer 4#.

[0104] Comparative Example 3

[0105] This comparative example provides a micro-foamed polypropylene material, the formula of which is different from that of Example 1 in that compatibilizer 1# is replaced by compatibilizer 5#.

[0106] Comparative Example 4

[0107] This comparative example provides a micro-foamed polypropylene material, the formula of which is different from that of Example 1 in that compatibilizer 1# is not added.

[0108] The properties of the micro-foamed polypropylene materials of each embodiment and comparative example were measured according to the above-mentioned test method. The test results are shown in Table 3.

[0109] Table 3 Performance test results of micro-foamed polypropylene materials of various embodiments and comparative examples

[0110]

[0111]

[0112] As can be seen from Table 3, the micro-foamed polypropylene materials of Examples 1 to 14 have a high weight reduction ratio and closed cell rate after foaming, wherein the weight reduction ratio can reach more than 29.7%, with a maximum of 38.1%; the closed cell rate can reach more than 94.7%, with a maximum of 98.8%; and the cantilever beam notched impact strength of the micro-foamed polypropylene material can be maintained at 28.9 KJ / m 2 The above meets the use requirements of the application scenario, and the highest reaches 49.7KJ / m 2 The above indicates that the micro-foamed polypropylene material of the present invention has a high closed cell rate and weight reduction ratio after foaming and can maintain good notched impact strength.

[0113] The melt index of the polypropylene resin added to Comparative Example 1 is not appropriate, and the weight loss ratio and closed cell rate of its micro-foamed polypropylene material after foaming are significantly lower; the grafting rate of the compatibilizer 4# added to Comparative Example 2 is too low, and the weight loss ratio and closed cell rate of its micro-foamed polypropylene material after foaming are also lower, especially the closed cell rate is low; the compatibilizer added to Comparative Example 3 is poly 1-butene grafted with sodium maleate, and the weight loss ratio and closed cell rate of its micro-foamed polypropylene material after foaming are also lower; Comparative Example 4 does not add the specific compatibilizer of the present invention, and the weight loss ratio and closed cell rate of its micro-foamed polypropylene material after foaming are also significantly lower.

[0114] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A micro-foamed polypropylene material, It is characterized in that The composition comprises the following components in parts by weight: The melt index of the polypropylene resin measured under the test conditions of 230° C. and 2.16 kg is 0.5 to 3 g / 10 min; The compatibilizer is ethylene-propylene-butylene terpolymer polypropylene grafted with sodium maleate, and the grafting rate is 1.5-3%; The ethylene-propylene-butadiene ternary copolymer polypropylene grafted with sodium maleate is prepared by the following method: mixing ethylene-propylene-butadiene ternary copolymer polypropylene, sodium maleate and an antioxidant to obtain a mixture for standby use; dissolving an initiator, α-methylstyrene and 1-octene in a solvent to obtain a mixed solution for standby use; adding the mixed solution to the mixture, and melt-extruding to obtain the ethylene-propylene-butadiene ternary copolymer polypropylene grafted with sodium maleate; The melt index of the ethylene-propylene-butadiene terpolymer polypropylene in the ethylene-propylene-butadiene terpolymer polypropylene grafted with sodium maleate is 5-9 g / 10 min when tested at 230° C. and 2.16 kg.

2. The micro-foamed polypropylene material according to claim 1, It is characterized in that The micro-foamed polypropylene material comprises the following components in parts by weight:

3. The micro-foamed polypropylene material according to claim 1, It is characterized in that The filler is at least one of talc, calcium carbonate or basic magnesium sulfate whisker.

4. The micro-foamed polypropylene material according to claim 1, It is characterized in that The toughening agent is at least one of ethylene-octene random copolymer, ethylene-butene random copolymer, metallocene linear low-density polyethylene, metallocene ethylene-propylene copolymer or hydrogenated styrene-butadiene-styrene linear triblock copolymer.

5. The micro-foamed polypropylene material according to claim 4, It is characterized in that The toughening agent is a hydrogenated styrene-butadiene-styrene linear triblock copolymer.

6. The micro-foamed polypropylene material according to claim 1, It is characterized in that The auxiliary agent is at least one of an antioxidant and a lubricant.

7. The method for preparing the micro-foamed polypropylene material according to any one of claims 1 to 6, It is characterized in that The method comprises the following steps: mixing the components, melt-extruding and granulating to obtain the micro-foamed polypropylene material.

8. Use of the micro-foamed polypropylene material according to any one of claims 1 to 6 in the preparation of automotive pressure-resistant and buffering parts.

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