A chemically resistant and antistatic polypropylene composite material, its preparation and application

Abstract

The present invention relates to a chemical-resistant and antistatic polypropylene composite material, its preparation and application. The components include: polypropylene, tetrapod-shaped zinc oxide whiskers, coupling agent, surfactant, toughening agent, antioxidant, graphene. The polypropylene composite material prepared by the above formula combination has excellent chemical resistance and at the same time takes into account good antistatic effect, and can be widely applied in the fields of automobiles, household appliances, etc.

Description

Technical Field

[0001] The present invention belongs to the field of polymer materials, and particularly relates to a chemically resistant and antistatic polypropylene composite material, its preparation and application. Background Art

[0002] As the general polymer material with the lowest density, polypropylene is widely used in industries such as automobiles and household appliances. However, its intolerance to some solvents, especially oily solvents, limits its scope of use. For example, the interior and exterior parts of automobiles will inevitably be exposed to chemical environments such as gasoline and oil stains. The poor chemical resistance of polypropylene will greatly reduce the service life of parts, affect the appearance of parts and even cause part failure.

[0003] In addition, as a non-polar and non-conductive polymer, polypropylene is prone to generate static electricity. Parts made of polypropylene materials are prone to attracting dust in the environment, affecting the product appearance. Even worse, there may be a risk of static electricity ignition, threatening the safety of production personnel and consumers.

[0004] Existing polypropylene materials all have the defects of poor chemical resistance and easy generation of static electricity. Summary of the Invention

[0005] Aiming at the defects of the existing technology, the purpose of the present invention is to provide a chemically resistant and antistatic polypropylene composite material, its preparation and application.

[0006] A chemically resistant and antistatic polypropylene composite material of the present invention comprises components by weight:

[0007]

[0008] Among them, the number average molecular weight of the surfactant is not more than 1000, and the test method is GB / T 27843-2011.

[0009] If the number average molecular weight is greater than 1000, the migration rate of the surfactant to the surface is slow, and it cannot play the role of blocking oily chemicals on the surface and the antistatic effect.

[0010] Preferably, the coupling agent is one or more of silane coupling agent, titanate coupling agent, and phosphate coupling agent. Preferably, the average length of the needle-shaped part of the tetrapod-like zinc oxide whisker is 10-150 um.

[0011] More preferably, the average length of the needle-shaped part of the tetrapod-like zinc oxide whisker is 20-100 um, and the test method: observed by electron microscope.

[0012] The average length of the needle-shaped part of the four-needle zinc oxide whisker is too short to form a skeleton effect in the polypropylene system, and the conductive efficiency is low. If the average length of the needle-shaped part of the four-needle zinc oxide whisker is too long, it is difficult to disperse in the polypropylene system, which has a significant negative effect on antistatic and chemical resistance.

[0013] Preferably, the number average molecular weight of the surfactant is 200-800.

[0014] If the number average molecular weight of the surfactant is too small, the migration speed of the surfactant is too fast and it cannot produce long-term chemical resistance and antistatic effects on the surface. If the number average molecular weight of the surfactant is too large, it is difficult for the surfactant to precipitate to the surface and it cannot produce chemical resistance and antistatic effects.

[0015] Preferably, the surfactant is a surfactant containing an oxygen polar group; wherein the surfactant containing an oxygen polar group is a surfactant having an oxygen polar group such as an ether group, a hydroxyl group, an ester group or an amide group.

[0016] Furthermore, the surfactant is one or more of polyoxyethylene ether surfactants, polyol fatty acid ester surfactants, and fatty alcohol amide surfactants.

[0017] Furthermore, the polyoxyethylene ether surfactant is at least one of polyethylene glycol monohexadecyl ether and polyethylene glycol monotetradecyl ether; the polyol fatty acid ester surfactant is at least one of glycerol hexadecanoate, 1-dodecanoic acid monoglyceride, glyceryl tri(tetradecanoate), and glyceryl tri(nonadecanoate); and the fatty alcohol amide surfactant is hexadecane diethanolamide.

[0018] Preferably, the antioxidant is one or more of phenolic, amine, phosphite, and semi-hindered phenolic antioxidants.

[0019] Preferably, the toughening agent is one or more of POE, EPDM and SEBS.

[0020] Preferably, the ingredients by weight include:

[0021]

[0022] A method for preparing the chemical-resistant and antistatic polypropylene composite material of the present invention comprises:

[0023] Weigh each component according to the ratio, mix polypropylene, toughening agent, surfactant and antioxidant, and feed the mixture into a twin-screw extruder from the main feeding port;

[0024] Mix the tetrapod-shaped zinc oxide whiskers, graphene, and coupling agent according to the ratio, and feed the mixture into the extruder from the side feeding port in the 3-5 zones of the extruder;

[0025] Obtain a chemical-resistant and antistatic polypropylene composite material through melt extrusion, strand drawing, cooling, granulation, and drying.

[0026] The mixing time is 3-5 min in all cases.

[0027] The melt extrusion temperature is 200-240 °C.

[0028] The application of the chemical-resistant and antistatic polypropylene composite material of the present invention in the interior and exterior trim of automobiles or household appliances, such as in parts vulnerable to chemical solvent erosion and having antistatic requirements, such as air conditioners, automobile door panels, instrument panels, center consoles, etc.

[0029] From the perspective of chemical resistance: The erosion of polypropylene by chemical reagents generally occurs in two steps; the first step is the wetting and penetration of the polypropylene surface. Generally, the crystalline region is difficult to penetrate, and the penetration mainly occurs in the amorphous region; the second step is that after the chemical penetrates into the amorphous region, the free volume in the amorphous region increases, and the appearance shows swelling, whitening, and other chemical resistance appearance failure phenomena. In addition, if only tetrapod-shaped zinc oxide whiskers are added to the polypropylene system, although tetrapod-shaped zinc oxide has a certain conductive effect, the conductive effect is relatively poor when the addition amount is relatively low, and it is easy to have uneven dispersion when the addition amount is relatively high, resulting in unstable conductive state, and the technical problem of the erosion of the polypropylene matrix by solvents cannot be solved.

[0030] In the present invention, a surfactant containing an oxygen-containing polar group can quickly migrate to the surface of polypropylene, form polar groups on the surface, and play a role in blocking oily chemicals; the graphene with a lamellar structure can also play a role in blocking the penetration of chemicals in the matrix; at the same time, the tetrapod-shaped zinc oxide has a good strengthening effect and plays a supporting role during the swelling process in the amorphous region, alleviating the failure process; the three cooperate with each other to greatly improve the chemical resistance effect of the composite material.

[0031] From the perspective of antistatic property: Tetrapod-shaped zinc oxide is an N-type semiconductor compound with conductivity. Its three-dimensional structure can easily form a connection network in the polypropylene system and has a permanent antistatic effect; graphene, as a super-strong conductive filler, can also be used as a conductive filler that cooperates with tetrapod-shaped zinc oxide in the system to further enhance the permanent antistatic effect; the surfactant is also a migrating antistatic agent. It migrates to the surface, and the polar groups formed on the surface can absorb moisture in the air and form a conductive water layer on the surface; the combination of the three can also greatly improve the antistatic effect of the system.

[0032] Beneficial effects

[0033] In the present invention, the synergistic use of a surfactant, graphene, and tetrapod-like zinc oxide can achieve both chemical resistance and extraordinary antistatic effects simultaneously. There is no swelling or obvious whitening phenomenon under the erosion of chemical reagents, especially oily solvents. The present invention simultaneously realizes the improvement of the comprehensive properties of mechanical properties, chemical resistance, and antistatic properties. Detailed implementation manners

[0034] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0035] I. Sources of raw materials

[0036] Polypropylene: PP 548R, manufacturer: CNOOC and Shell Chemicals;

[0037] Tetrapod-like zinc oxide whisker - 1: Yingkou Weiske Chemical Co., Ltd., average length of the needle-like part is 50 μm;

[0038] Tetrapod-like zinc oxide whisker - 2: Yingkou Weiske Chemical Co., Ltd., average length of the needle-like part is 20 μm;

[0039] Tetrapod-like zinc oxide whisker - 3: Yingkou Weiske Chemical Co., Ltd., average length of the needle-like part is 100 μm;

[0040] Tetrapod-like zinc oxide whisker - 4: Yingkou Weiske Chemical Co., Ltd., average length of the needle-like part is 10 μm;

[0041] Tetrapod-like zinc oxide whisker - 5: Yingkou Weiske Chemical Co., Ltd., average length of the needle-like part is 150 μm;

[0042] Coupling agent: Silane coupling agent, KH-560, manufacturer: Nanjing Shuguang Silane Chemical Co., Ltd.;

[0043] Toughening agent: POE 7447, manufacturer: DOW;

[0044] Graphene: SG-01005, manufacturer: Nanjing Kefu Nanotechnology Co., Ltd.;

[0045] Antioxidant: Hindered phenol antioxidant 1010; Phosphite antioxidant 168, with a mass ratio of 1:1;

[0046] Surfactant - 1 polyol fatty acid ester: Monoglyceryl laurate, number average molecular weight 274, Zhejiang Jiahua Fine Chemical Co., Ltd.;

[0047] Surfactant - 2 Polyol Fatty Acid Esters: Tristearin, number - average molecular weight 724, Zhejiang Jiahua Fine Chemical Co., Ltd.;

[0048] Surfactant - 3 Polyol Fatty Acid Esters: Tri(nonadecanoic acid) glyceride, number - average molecular weight 934, Zhejiang Jiahua Fine Chemical Co., Ltd.;

[0049] Surfactant - 4 Polyoxyethylene Ethers: Polyethylene glycol monocetyl ether, number - average molecular weight 400; Zhejiang Jiahua Fine Chemical Co., Ltd.;

[0050] Surfactant - 5 Polyethylene glycol monocetyl ether, number - average molecular weight 1500, Zhejiang Jiahua Fine Chemical Co., Ltd.;

[0051] The toughening agent and antioxidant used in the parallel examples and comparative examples are the same commercially available products.

[0052] II. Preparation Methods of Examples and Comparative Examples

[0053] Weigh each component according to the ratio. Mix polypropylene, toughening agent, surfactant, and antioxidant in a high - speed mixer for 3 - 5 min, and then put the mixture into a twin - screw extruder from the main feeding port;

[0054] Mix tetrapod - shaped zinc oxide whiskers, graphene, and coupling agent in a high - speed mixer for 3 - 5 min according to the ratio, and then put the mixture into the extruder from the side feeding port in the 3 - 5 zone of the extruder;

[0055] Obtain the chemical - resistant antistatic polypropylene composite material through melt extrusion, strand drawing, cooling, pelletizing, and drying.

[0056] The ratio of the length to the diameter of the twin - screw extruder is 75:1, the extrusion temperature is 200 - 240 °C, the screw speed is 500 rpm, the total feeding amount is 550 kg / h, and the vacuum degree is ≤ - 0.08 bar.

[0057] III. Test Standards and Methods

[0058] 1. Gasoline Resistance Test:

[0059] Refer to Standard Q / JLY J7110281D - 2016 5.11. Wipe the surface of a 100*100*2 mm specimen 10 times with a cloth soaked in gasoline, stand it vertically in an indoor environment at (23 ± 2) °C for 1 h, and then detect the surface condition of the specimen. Then store it in a test chamber at a temperature of (90 ± 2) °C for 1 h and detect the appearance state of the sample.

[0060] Table 1 Appearance Grade

[0061] Appearance grade Grade description 1 No change in appearance 2 Slight oil stain 3 Obvious oil stain 4 Severe oil stain 5 Swelling, deformation, whitening

[0062] Note: For the gasoline resistance appearance grade, Grade 1 is the best and Grade 5 is the worst.

[0063] 2. Surface resistivity: The test standard is GB1410—2006 "Test Method for Surface Resistivity of Solid Insulating Materials".

[0064] 3. Tensile strength: The test standard is ISO 527-2 2012, the test temperature is 23°C, and the tensile speed is 50 mm / min.

[0065] Table 2 Formulation of Examples (parts by weight)

[0066]

[0067] Table 3 Formulation of Comparative Examples (parts by weight)

[0068]

[0069] It can be seen from the examples that in the polypropylene composite material of the present invention, the gasoline resistance appearance grade can reach Grade 1-2, and the surface resistivity can reach below 10^10, having a good antistatic effect. At the same time, the tensile strength can reach above 22 Mpa.

[0070] It can be seen from Examples 1-5 that the size of the tetrapod-like zinc oxide whiskers will affect the chemical resistance and antistatic properties. For example, in Example 4, the average length of the needle-like part of the tetrapod-like zinc oxide whiskers is relatively short, and it cannot form a good framework in the polypropylene system, resulting in poorer chemical resistance than Examples 1-2, and at the same time, the conductivity efficiency is low. For example, in Example 5, the average length of the needle-like part of the tetrapod-like zinc oxide whiskers is too long, making it difficult to disperse in the polypropylene system, and the antistatic and chemical resistance are poorer than Examples 1-2.

[0071] Comparing Example 1 with Comparative Examples 1-3, it can be seen that the interaction between the tetrapod-like zinc oxide whiskers, the surfactant, and graphene improves the chemical resistance and antistatic properties.

[0072] In Comparative Example 6, the addition amount of the tetrapod-like zinc oxide whiskers is too high, and the whiskers are unevenly dispersed in the composite matrix, resulting in a decrease in the tensile strength of the composite material, local failure in the gasoline resistance experiment, and the inability to form a good conductive path in the body, and the resistivity increases.

[0073] In Comparative Example 7, the addition amount of the surfactant is too high, which has no obvious negative effect on the antistatic and chemical resistance effects, but the tensile strength is significantly reduced. At the same time, too much surfactant migrates to the surface, which will affect the surface appearance, and at the same time, it has a very serious negative impact on the odor and volatile organic compounds (VOC) of the composite material.

[0074] In Comparative Example 8, the addition amount of graphene is too high, which easily causes agglomeration in the matrix. The conductive effect of the agglomerated graphene is poor, resulting in an increase in resistivity; and the barrier efficiency against gasoline decreases, leading to a slight decrease in chemical resistance.

Claims

1. A polypropylene composite material, characterized in that, the component parts by weight include: 65 - 95 parts of polypropylene; 5 - 15 parts of tetrapod zinc oxide whiskers; 0.5 - 1.5 parts of coupling agent; 0.2 - 1 part of surfactant; 0.5 - 3 parts of graphene; 0.1 - 0.8 part of antioxidant; 0 - 10 parts of toughening agent; wherein the number average molecular weight of the surfactant is not more than 1000; wherein the average length of the needle-like part of the tetrapod zinc oxide whiskers is 10 - 150 um; the surfactant is one or several of polyoxyethylene ether surfactants, polyol fatty acid ester surfactants, and fatty alcohol amide surfactants.

2. The polypropylene composite material according to claim 1, characterized in that, the average length of the needle-like part of the tetrapod zinc oxide whiskers is 20 - 100 um.

3. The polypropylene composite material according to claim 1, characterized in that, the number average molecular weight of the surfactant is 200 - 800.

4. The polypropylene composite material according to claim 1, characterized in that, the coupling agent is one or several of silane coupling agents, titanate coupling agents, and phosphate coupling agents.

5. The polypropylene composite material according to claim 1, characterized in that, the polyoxyethylene ether surfactant is at least one of polyethylene glycol monocetyl ether and polyethylene glycol monotetradecyl ether; the polyol fatty acid ester surfactant is at least one of glycerol monopalmitate, glycerol monolaurate, glycerol tri(tetradecanoate), and glycerol tri(nonadecanoate); the fatty alcohol amide surfactant is hexadecyl diethanolamide.

6. The polypropylene composite material according to claim 1, characterized in that, the antioxidant is one or several of phenols, amines, and phosphites; the toughening agent is one or several of POE, EPDM, and SEBS.

7. The polypropylene composite material according to claim 1, characterized in that, the component parts by weight include: 75 - 86 parts of polypropylene; 8 - 12 parts of tetrapod zinc oxide whiskers; 0.8 - 1.2 parts of coupling agent; 0.5 - 0.8 part of surfactant; 1 - 2 parts of graphene; 0.2 - 0.5 part of antioxidant; 5 - 8 parts of toughening agent.

8. A preparation method of the polypropylene composite material according to claim 1, including: weighing each component according to the ratio, mixing polypropylene, toughening agent, surfactant, and antioxidant, and feeding the mixture into a twin-screw extruder from the main feed port; mixing tetrapod zinc oxide whiskers, graphene, and coupling agent according to the ratio, and feeding the mixture into the extruder from the side feed port in the 3 - 5 zones of the extruder; obtaining a chemically resistant and antistatic polypropylene composite material through melt extrusion, strand drawing, cooling, pelletizing, and drying.

9. An application of the polypropylene composite material according to any one of claims 1 - 7 in automotive interior and exterior trims or household appliances.

Images