Polypropylene composite material, and preparation method and application thereof

Abstract

The application relates to a polypropylene composite material and a preparation method and application thereof, and belongs to the technical field of modified polypropylene plastics. The polypropylene composite material comprises the following components in parts by weight: polypropylene resin 45-75 parts, inorganic filler 10-30 parts, toughening agent 5-15 parts, chlorinated EVA 5-10 parts and compatilizer 3-8 parts; the compatilizer is an alpha, beta-unsaturated carbonyl compound grafted polyolefin thermoplastic elastomer. The polypropylene composite material adopts chlorinated EVA (CEVA) and alpha, beta-unsaturated carbonyl compound grafted polyolefin thermoplastic elastomer compounding, can make the surface tension of the polypropylene composite material obviously better than that of ordinary polypropylene or modified material, can respectively enhance the compatibility with the polypropylene resin and the toughening agent, and is also beneficial to improving the adhesion effect and moisture resistance of the material.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of modified polypropylene plastics, and particularly relates to a polypropylene composite material and a preparation method and application thereof. BACKGROUND

[0002] Since the polypropylene material is a non-polar crystalline material with low surface energy, the surface adhesion thereof is poor. If the surface of a part made of the polypropylene material is not pretreated, it is difficult to perform paint spraying. At present, the methods for improving the surface adhesion of the polypropylene material mainly include flame treatment, corona treatment, chemical oxidation treatment and the like. The technical difficulties of these methods are to form a uniform surface and not to be over-treated, so as to affect the performance of the material. At present, the flame treatment is the most commonly used method. If the flame treatment is not proper, unqualified products are easily generated, such as part deformation, difficult assembly, local burning of the part and scrap.

[0003] CN105367906A discloses a flame treatment-free polypropylene composite and a preparation method thereof, which comprises the following components and their weight parts: polypropylene 65-90 parts, ethylene-octene copolymer 0-20 parts, high-density polyethylene 5-15 parts, ethylene-vinyl acetate copolymer 1-20 parts, thermal stabilizer 0.2-2 parts, and processing aid 0.2-2 parts. The ethylene-vinyl acetate copolymer is added in the raw materials to improve the polarity. However, after the polypropylene composite is injection molded into an automobile exterior bumper, direct paint spraying still causes paint peeling, and the water resistance of the material after paint spraying is relatively low, which is not suitable for the preparation of automobile exterior parts.

[0004] CN106750951A discloses a flame treatment-free sprayable polypropylene composite and a preparation method thereof, which is composed of the following raw materials in percentage by weight: polypropylene 48-97%, inorganic filler 15-25%, elastomer toughening agent 5-15%, compatibilizer 0-3%, surface lubricant 0-1%, stabilizer 0.1-2%, and other additives 0-5%. If the polypropylene composite is directly painted without flame treatment, about 10-15% of the paint will peel off, which cannot meet the use of automobile exterior parts.

[0005] Therefore, it is urgent to develop a polypropylene composite material with high paint adhesion and excellent moisture resistance. SUMMARY

[0006] The application aims to overcome the deficiencies of the prior art and provide a polypropylene composite material with high paint adhesion and excellent moisture resistance.

[0007] To achieve the above-mentioned purpose, the technical scheme adopted by the application is as follows:

[0008] In a first aspect, the present application provides a polypropylene composite material, comprising the following components by weight: 45-75 parts of polypropylene resin, 10-30 parts of inorganic filler, 5-15 parts of toughening agent, 5-10 parts of chlorinated EVA, and 3-8 parts of compatibilizer, wherein the compatibilizer is an alpha, beta-unsaturated carbonyl compound grafted polyolefin thermoplastic elastomer.

[0009] The inventors of the present application have found that the surface tension of the polypropylene composite material is significantly better than that of ordinary polypropylene or modified material by compounding chlorinated EVA (CEVA) and a specific compatibilizer. The compatibilizer has good interfacial affinity with the inorganic filler. The alpha, beta-unsaturated carbonyl compound, as a multifunctional monomer, contains a carbonyl group and a carbon-carbon double bond. When it is grafted onto the polyolefin thermoplastic elastomer, more double bonds become initiation points for growth, and the grafted chains are easy to form crosslinked structures, thereby forming a grafted layer with a body structure on the surface. At the same time, the compatibilizer has good synergistic effect with CEVA, which can enhance the compatibility with polypropylene resin and toughening agent, respectively, and is beneficial to the preparation of the polypropylene composite material.

[0010] In addition, the inventors of the present application have found that the ester group of CEVA in the composite compatibilizer can have good reactivity with the isocyanate group in the primer, and form a chemical bond. The chlorine element in CEVA is more easily infiltrated into the surface of polypropylene, thereby improving the adhesion of the material.

[0011] As a preferred embodiment of the polypropylene composite material of the present application, the alpha, beta-unsaturated carbonyl compound is selected from at least one of trimethylolpropane triacrylate, glycidyl methacrylate, and N-isopropyl acrylamide.

[0012] The inventors of the present application have found that grafting trimethylolpropane triacrylate (TMPTA), glycidyl methacrylate (GMA), or N-isopropyl acrylamide (NIPAAm) onto the polyolefin thermoplastic elastomer can make the prepared compatibilizer have more excellent compatibility with CEVA and polypropylene resin. At the same time, the specific alpha, beta-unsaturated carbonyl compound can further enhance the reactivity of the polypropylene composite material with the primer, so that the polypropylene composite material has higher paint adhesion.

[0013] As a more preferred embodiment of the polypropylene composite material of the present application, the alpha, beta-unsaturated carbonyl compound is N-isopropyl acrylamide.

[0014] The inventors of the present application have found that, compared with other alpha, beta-unsaturated carbonyl compounds, the reaction activity of the amide group and the isocyanate group in N-isopropyl acrylamide is higher than that of the hydroxyl group, the carboxylic acid group and the ester group, so the effect of improving the paint adhesion is more remarkable, which can help the grafting product to crosslink with chlorinated EVA and PP, improve the compatibility, and has good reaction activity with the isocyanate group in the primer, form a chemical bond, and improve the paint adhesion.

[0015] As a preferred embodiment of the polypropylene composite material of the present application, the grafting rate of the alpha, beta-unsaturated carbonyl compound in the compatilizer is 8-16%.

[0016] The inventors of the present application have found that, compared with other alpha, beta-unsaturated carbonyl compounds, the reaction activity of the amide group and the isocyanate group in N-isopropyl acrylamide is higher than that of the hydroxyl group, the carboxylic acid group and the ester group, so the effect of improving the paint adhesion is more remarkable, which can help the grafting product to crosslink with chlorinated EVA and PP, improve the compatibility, and has good reaction activity with the isocyanate group in the primer, form a chemical bond, and improve the paint adhesion.

[0017] As a more preferred embodiment of the polypropylene composite material of the present application, the grafting rate of the alpha, beta-unsaturated carbonyl compound in the compatilizer is 12-14%.

[0018] The present application uses the compatilizer with the above grafting rate to compound with chlorinated EVA and polypropylene resin, so that the polypropylene composite material has the best paint adhesion.

[0019] Grafting rate determination method: the oxygen content of the compatilizer is measured by Heracus-C.H.N.O.S element analyzer, and the grafting rate M is calculated by the formula: M:P=(N1 / N2)×oxygen content; M=P / (100-P). Wherein N1 is the molecular weight of the active monomer, and N2 is the molecular weight of oxygen.

[0020] As a preferred embodiment of the polypropylene composite material of the present application, the mass percentage of chlorine element in the chlorinated EVA is 15-35% measured by ICP method.

[0021] The inventors of the present application have found through a large number of experimental researches on the mass percentage of chlorine element in the chlorinated EVA that, when the mass percentage of chlorine element in the chlorinated EVA is in the above range, the surface tension of the polypropylene composite material can be effectively improved, so that it has a higher dyne value, thereby improving the adhesion effect and moisture resistance of the material. When the content of chlorine element is low, the effect of improving the paint adhesion of the material is poor; and when the content of chlorine element is high, the compatibility of CEVA and PP is poor, and the surface appearance and physical and chemical properties are poor.

[0022] As a more preferred embodiment of the polypropylene composite material, the content of chlorine element in the chlorinated EVA is 22-28% by mass.

[0023] The inventors of the present application have found that, when the content of chlorine element in the chlorinated EVA is within the above range, the polypropylene composite material prepared has the best dyne value and the best moisture resistance and paint adhesion.

[0024] As a preferred embodiment of the polypropylene composite material, the toughening agent is an ethylene and alpha-olefin copolymer containing 3-10 carbon atoms, and the melt flow rate of the toughening agent is 0.5-20 g / 10 min as determined according to ISO 1133 at 190°C and 2.16 kg.

[0025] As a preferred embodiment of the polypropylene composite material, the polypropylene resin is at least one of homopolymer polypropylene and copolymer polypropylene, and the melt flow rate of the polypropylene resin is 1-100 g / 10 min as determined according to ISO 1133 at 230°C and 2.16 kg.

[0026] As a preferred embodiment of the polypropylene composite material, the inorganic filler is at least one of talc, wollastonite, mica, barium sulfate, and magnesium sulfate whisker, and the particle size of the inorganic filler is 1-10 μm.

[0027] In a second aspect, the present application provides a preparation method of the above polypropylene composite material, comprising the following steps:

[0028] S1. Weighing the components of the polypropylene composite material in proportion, mixing uniformly to obtain a premix;

[0029] S2. Melting extruding and granulating drying the premix of step S1 to obtain the polypropylene composite material.

[0030] As a preferred embodiment of the preparation method of the polypropylene composite material, in step S2, the process parameters of the melting extrusion are as follows: the temperature of zone 1 is 140-180°C, the temperature of zone 2 is 220-240°C, the temperature of zone 3 is 230-270°C, the temperature of zone 4 is 230-270°C, the temperature of zone 5 is 230-270°C, the temperature of zone 6 is 230-270°C, the temperature of zone 7 is 230-270°C, the temperature of zone 8 is 230-270°C, the temperature of zone 9 is 230-270°C, the rotation speed of the main machine is 250-600 rpm, and the length-diameter ratio of the twin-screw extruder is 40:1.

[0031] As a preferred embodiment of the preparation method of the polypropylene composite material, the preparation method of the alpha, beta-unsaturated carbonyl compound grafted polyolefin thermoplastic elastomer comprises the following steps:

[0032] S1, the components in the alpha, beta-unsaturated carbonyl compound grafted polyolefin thermoplastic elastomer are weighed proportionally, mixed uniformly, and a mixture A is obtained;

[0033] S2, the initiator is added to the mixture A in step S1, a melt grafting reaction is carried out, the extruded sample is air-cooled and then granulated, and the alpha, beta-unsaturated carbonyl compound grafted polyolefin thermoplastic elastomer is obtained.

[0034] and / or

[0035] S1, the polyolefin thermoplastic elastomer is heated to dissolution in a reactor;

[0036] S2, the initiator is dissolved in the alpha, beta-unsaturated carbonyl compound to form a mixture, and the mixture is added to the reactor in step S1 for reaction, and after the reaction is completed, drying is carried out, and the alpha, beta-unsaturated carbonyl compound grafted polyolefin thermoplastic elastomer is obtained.

[0037] In a third aspect, the application further provides an application of the above-mentioned polypropylene composite material in preparing an automobile exterior paint spraying polypropylene material, such as an automobile bumper coating.

[0038] Compared with the prior art, the application has the following beneficial effects:

[0039] (1) The polypropylene composite material prepared by the application has a surface tension obviously better than that of ordinary polypropylene or modified materials, because the chlorinated EVA (CEVA) and the specific compatilizer are compounded; the compatilizer has good interfacial affinity with inorganic fillers, the alpha, beta-unsaturated carbonyl compound as a multifunctional monomer contains a carbonyl group and a carbon-carbon double bond, and when it is grafted to the polyolefin thermoplastic elastomer, more double bonds can become initiation growth points, and the grafted chain is easy to form a crosslinked structure, so that a grafted layer with a three-dimensional structure is formed on the surface; at the same time, the compatilizer has good synergistic effect with the CEVA, and can enhance the compatibility with the polypropylene resin and the toughening agent respectively, which is beneficial to the preparation of the polypropylene composite material.

[0040] (2) In the composite compatilizer, the ester group of the CEVA and the specific functional group in the alpha, beta-unsaturated carbonyl compound have good reactivity with the isocyanate group in the primer, a chemical bond is formed, and the chlorine element in the CEVA is more easily infiltrated into the surface of the polypropylene, so as to improve the adhesion effect and moisture resistance of the material. DETAILED DESCRIPTION

[0041] The technical solutions of the present application are further described below in combination with examples. Obviously, the described examples are only some of the examples of the present application, rather than all the examples. Based on the examples in the present application, all other examples obtained by those of ordinary skill in the art without creative effort are within the scope of the present application. The methods or operations used in the examples, if not specifically described, are conventional methods or conventional operations in the art.

[0042] In the examples, the materials, reagents, etc. used, if not specifically described, can be obtained commercially; the polypropylene resins, inorganic fillers, toughening agents, chlorinated EVA, trimethylolpropane triacrylate, and polyolefin thermoplastic elastomers used in the examples and comparative examples of the present application are all conventional commercially available products.

[0043] The raw materials used in the examples and comparative examples are described as follows, but are not limited to these materials:

[0044] Copolymerized polypropylene resin 1 (PP 1): PP EP548R, melt flow rate 30 g / 10 min (test conditions: 230℃, 2.16 kg, ISO 1133), Sinopec Lubricant Co., Ltd.

[0045] Copolymerized polypropylene resin 2 (PP 2): PP K9017, melt flow rate 15 g / 10 min (test conditions: 230℃, 2.16 kg, ISO 1133), Taiwan Chemical Fiber Co., Ltd.

[0046] Copolymerized polypropylene resin 3 (PP 3): PPB-MP10 (SP179P), melt flow rate 10 g / 10 min (test conditions: 230℃, 2.16 kg, ISO 1133), Qilu Petrochemical.

[0047] Copolymerized polypropylene resin 4 (PP 4): PP BX3920, melt flow rate 100 g / 10 min (test conditions: 230℃, 2.16 kg, ISO 1133), SK.

[0048] Talc (inorganic filler): commercially available; the talc used in the examples and comparative examples of the present application is all purchased from Liaoning Tianyuan New Energy Co., Ltd., and the particle size is 5 μm.

[0049] POE (toughening agent): commercially available; the POE used in the examples and comparative examples of the present application has a melt flow rate of 10 g / 10 min at 190℃, 2.16 kg according to ISO 1133.

[0050] Chlorinated EVA 1-5 can be selected from commercially available or self-made, and the examples use self-made, and the preparation method includes the following steps:

[0051] S1, adding emulsifier, dispersant and initiator into a chlorination kettle, then adding EVA powder, and passing in chlorine gas under the condition of 20-50℃ and carrying out reaction;

[0052] S2, centrifuging the product obtained in step S1, and neutralizing to pH=8, then carrying out extrusion and pelletizing, to obtain chlorinated EVA.

[0053] The relationship between the mass percentage of chlorine element in the chlorinated EVA 1-5 and the temperature in step S1 is as follows:

[0054] Chlorinated EVA 1 (CEVA 1): the mass percentage of chlorine element is 10±3%, and the temperature is 25℃.

[0055] Chlorinated EVA 2 (CEVA 2): the mass percentage of chlorine element is 18±3%, and the temperature is 32℃.

[0056] Chlorinated EVA 3 (CEVA 3): the mass percentage of chlorine element is 25±3%, and the temperature is 36℃.

[0057] Chlorinated EVA 4 (CEVA 4): the mass percentage of chlorine element is 32±3%, and the temperature is 42℃.

[0058] Chlorinated EVA 5 (CEVA 5): the mass percentage of chlorine element is 40±3%, and the temperature is 48℃.

[0059] EVA: V6020M extended petrification.

[0060] The compatilizers 1-8 are α, β-unsaturated carbonyl compound grafted polyolefin thermoplastic elastomers, wherein the components of the α, β-unsaturated carbonyl compound, the grafting rate, and the mass ratio of the polyolefin thermoplastic elastomer, the α, β-unsaturated carbonyl compound, and styrene in the raw material are shown in Table 1 below; the polyolefin thermoplastic elastomers are all ethylene-octene copolymers, and the crystallinity is all 10.0%. The compatilizers 1-8 are all self-made, and the preparation method comprises the following steps:

[0061] S1, uniformly mixing the polyolefin thermoplastic elastomer, the α, β-unsaturated carbonyl compound, and the styrene according to the mass ratio to obtain a mixture A;

[0062] S2, adding an initiator (the mass ratio of the initiator to the polyolefin thermoplastic elastomer is 10:2000) into the mixture A in step S1, carrying out a melt grafting reaction, and granulating the extruded sample after air cooling to obtain the α, β-unsaturated carbonyl compound grafted polyolefin thermoplastic elastomer.

[0063] Table 1

[0064]

[0065] Compatibilizer 9 (maleic anhydride grafted polypropylene, PP-g-MAH): CMG9801, Jiaiyirong Compatibilizer Jiangsu Co., Ltd.

[0066] The test method of the crystallinity of the ethylene-octene copolymer and the toughening agent according to the present application is as follows: differential scanning calorimetry is used, and the reference test standard is ISO 11357-2016.

[0067] Examples 1-20 and Comparative Examples 1-9

[0068] Examples 1-20 and Comparative Examples 1-9 are polypropylene composites according to the present application. The components of the polypropylene composites of Examples 1-20 and Comparative Examples 1-9 and their weight parts are shown in Tables 2-4 (the total weight parts are all 100 parts).

[0069] The preparation method of the polypropylene composites of Examples 1-20 and Comparative Examples 1-9 comprises the following steps:

[0070] S1, the components in the polypropylene composite are weighed according to the proportion, mixed uniformly, and a premix is obtained;

[0071] S2, the premix of step S1 is melt-extruded, granulated and dried to obtain the polypropylene composite; wherein the process parameters of melt-extrusion are as follows: the temperature of the first zone is 160℃, the temperature of the second zone is 230℃, the temperature of the third zone is 250℃, the temperature of the fourth zone is 250℃, the temperature of the fifth zone is 250℃, the temperature of the sixth zone is 250℃, the temperature of the seventh zone is 250℃, the temperature of the eighth zone is 250℃, the temperature of the ninth zone is 250℃, and the main machine speed is 400 revolutions / minute; the length-diameter ratio of the twin-screw extruder is 40:1.

[0072] Table 2 Weight parts: parts

[0073]

[0074] Table 3 Weight parts: parts

[0075]

[0076]

[0077] Table 4 Weight parts: parts

[0078]

[0079]

[0080] Effect example

[0081] The polypropylene composite materials of Examples 1-20 and Comparative Examples 1-9 of the present application were injection molded into 150mm x 200mm x 3mm plaques for dyne value, moisture resistance and steam jet test performance tests. The test methods were as follows:

[0082] (1) Dyne value: dyne value was tested using an A. Shine dyne pen;

[0083] (2) Moisture resistance: the plaques were painted with Akzo paints, and then tested according to TL211 condensation water test requirements, with a temperature of 40°C, a humidity of 100%, a test time of 10 days, and the bubbling phenomenon was observed, and the grade was determined according to Table 5;

[0084] (3) Steam jet test: the plaques were painted with Akzo paints, and then tested according to DIN EN ISO6270-2 condensation water test, and then tested according to PV1503 A method for high pressure water test, and the steam jet test result evaluation grade criteria are shown in Table 6.

[0085] Table 5

[0086]

[0087] Table 6

[0088]

[0089] The test results are shown in Table 7.

[0090] Table 7

[0091]

[0092]

[0093] As can be seen from Table 7, when the technical solution of the present application is used, the product obtained has excellent moisture resistance and paint adhesion, and the dyne value can reach 40, the moisture resistance grade reaches S2 or above, and the steam jet test grade reaches 2 or above.

[0094] Comparing Examples 1-5 and Comparative Examples 1-2, it can be seen that the chlorine element content of chlorinated EVA has a significant effect on the surface tension, paint adhesion and moisture resistance of the product, and when the mass percentage of chlorine element in the chlorine of chlorinated EVA is in the range of 22-28%, the comprehensive performance of the product obtained is more excellent, specifically, the dyne value is 44 or above, and the steam jet test grade reaches 1 or 0.

[0095] Comparative Examples 6-12 and Comparative Examples 3-4 show that the grafting of the α,β-unsaturated carbonyl compound onto the polyolefin thermoplastic elastomer as the compatibilizer has a great influence on the surface tension and paint adhesion of the product, especially the grafting rate of the α,β-unsaturated carbonyl compound in the compatibilizer. When the grafting rate of the α,β-unsaturated carbonyl compound in the compatibilizer is in the range of 12-14%, the product has more excellent dyne value and higher steam jet test grade, indicating that the product has better compatibility and paint adhesion.

[0096] Comparative Examples 13-16 and Comparative Examples 5-8 show that when the addition amount of the chlorinated EVA or the compatibilizer is not in the range of the present application, the compatibility, paint adhesion and moisture resistance of the product are affected. The dyne value of Comparative Examples 5-8 is between 36-38, the steam jet test grade is 3-4, and the paint adhesion of the product is significantly decreased. Meanwhile, Comparative Example 3 and Comparative Example 9 show that when the chlorinated EVA and the compatibilizer are not contained, the compatibility of the polypropylene resin and the toughening agent is poor, resulting in a dyne value of 32 for the product of Comparative Example 9, a steam jet test grade of 4, and poor paint adhesion. Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application and are not a limitation on the protection scope of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A polypropylene composite, characterized in that, The polypropylene composite material comprises the following components by weight: polypropylene resin 45-75 parts, inorganic filler 10-30 parts, toughening agent 5-15 parts, chlorinated EVA 5-10 parts, and compatibilizer 3-8 parts. The compatibilizer is an α, β-unsaturated carbonyl compound grafted polyolefin thermoplastic elastomer. In the compatibilizer, the α, β-unsaturated carbonyl compound is at least one selected from trimethylolpropane triacrylate, glycidyl methacrylate, and N-isopropyl acrylamide. The mass percentage of chlorine in the chlorinated EVA is 15-35%.

2. The polypropylene composite of claim 1, wherein, The grafting rate of the α, β-unsaturated carbonyl compound in the compatibilizer is 8-16%.

3. The polypropylene composite of claim 2, wherein the polypropylene is a homopolymer of propylene. The grafting rate of the α, β-unsaturated carbonyl compound in the compatibilizer is 12-14%.

4. The polypropylene composite of claim 1, wherein, The mass percentage of chlorine in the chlorinated EVA is 22-28%.

5. The polypropylene composite of claim 1, wherein the polypropylene is a homopolymer of propylene. The toughening agent is a copolymer of ethylene and an α-olefin containing 3-10 carbon atoms, and the melt flow rate of the toughening agent is 0.5-20 g / 10 min under the condition of 190 ℃ and 2.16 kg as determined according to ISO 1133.

6. The polypropylene composite of claim 1, wherein, The polypropylene resin is at least one selected from homopolymer polypropylene and copolymer polypropylene, and the melt flow rate of the polypropylene resin is 1-100 g / 10 min under the condition of 230 ℃ and 2.16 kg as determined according to ISO 1133.

7. Process for the production of polypropylene composites according to any one of claims 1 to 6, characterized in that, The method comprises the following steps: S1, weighing the components in the polypropylene composite material in proportion, mixing uniformly to obtain a premix; S2, melt extruding and drying the premix to obtain the polypropylene composite material.

8. Use of the polypropylene composite material according to any one of claims 1-6 in the preparation of an automobile exterior paint spraying polypropylene material.

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