A polypropylene composite material and its preparation method and application

Abstract

The invention discloses a polypropylene composite material and a preparation method and application thereof, belonging to the technical field of polymer materials. The polypropylene composite material comprises the following components by weight: 100 parts of polypropylene, 5 to 35 parts of inorganic filler, 5 to 25 parts of toughening agent, 0.2 to 0.8 parts of coupling agent, 0.2 to 0.8 parts of antioxidant, 0.2 to 0.8 parts of light stabilizer, 0.2 to 0.8 parts of lubricant, 0.5 to 1.0 parts of halloysite nanotubes, and 0.008 to 0.05 parts of alkaline inorganic salt. The alkaline inorganic salt and halloysite nanotube in the polypropylene composite material of the invention can be used as an acid scavenger and an adsorbent to remove acidic substances in the material through a neutralization reaction and reduce odor.

Description

Technical Field

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

[0002] Polypropylene materials have been widely used in the automotive and home appliance industries in recent years due to their low cost, light weight, good chemical resistance, excellent processing performance, and easy recycling. They are especially used in automotive interior and exterior trims, such as door trim panels, dashboards, pillars, seat guards, bumpers, side surrounds, deflectors, fenders, etc. With the growing development of the automotive industry and the increasing awareness of environmental protection and health among consumers, people not only require cars to have spacious interior space, wide vision, and comfortable rides, but also require fresh and high-quality air in the car. Volatile harmful substances in cars have attracted people's attention, which is directly reflected in the perception of odors. Studies have shown that the sources of odors in cars are multifaceted, and volatile organic compounds (VOCs) from interior components are one of the main reasons affecting the air quality in cars.

[0003] Most interior parts contain a certain amount of volatile organic compounds, which are mainly alkanes, olefins, aromatics, amines, phenols, thiols, peroxides, aldehydes, and ketones produced by the decomposition of polypropylene during processing. The boiling points of these substances are usually within the range of 50 to 260 ° C. When the temperature reaches a certain height, under the action of light and heat, an uncomfortable odor is produced, and even headaches, dry coughs, allergies and other discomfort reactions are caused. On March 1, 2012, GB / T27630-2011 "Guidelines for the Evaluation of Air Quality in Passenger Cars" came into effect, proposing limit requirements for 8 substances such as benzene and aldehydes in the air of the entire vehicle compartment. Automotive interior parts are one of the main sources of air pollution in the car compartment, and modified polypropylene materials are one of the main materials for manufacturing automotive interior parts. Therefore, the preparation of modified polypropylene materials with low odor and low volatile organic compounds has become a new hot spot for modified plastics.

[0004] Moreover, during the decomposition of polypropylene, a sour smell is generated. The sour smell can cause nausea and palpitations. Therefore, the sour smell needs to be controlled. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the defects and shortcomings of the existing polypropylene composite materials, that is, the high sour taste, and to provide a polypropylene composite material, which can remove the acidic substances in the material and reduce the sour taste and odor of the material.

[0006] Another object of the present invention is to provide a method for preparing a polypropylene composite material.

[0007] Another object of the present invention is to provide an application of a polypropylene composite material in the preparation of automobile interior decoration.

[0008] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0009] A polypropylene composite material, comprising the following components by weight:

[0010]

[0011] The melt mass flow rate of polypropylene is 10-100 g / 10 min, the test standard is ISO 1133-1-2011, and the test conditions are 230° C. and 2.16 kg.

[0012] The polypropylene composite material of the present invention will be decomposed by heat during the preparation process, so volatile organic compounds such as aldehydes, benzenes and other small molecular organic substances will exist.

[0013] The role of inorganic fillers is to improve the rigidity of polypropylene composite materials. However, the addition of fillers increases the viscosity of the system, and the thermal decomposition during the granulation process intensifies, producing acidic substances and reducing the heat resistance of polypropylene. In addition, due to the molecular weight of polypropylene being broken, volatile organic compounds such as aldehydes, benzene and small molecular organic matter will also exist.

[0014] The role of toughening agent is to improve the toughness of polypropylene composite materials, but since acidic substances are also produced during its synthesis process and the heat resistance of polypropylene is reduced, these raw materials also contain certain volatile aldehydes, benzenes and small molecular organic matter, which significantly increases the TVOC and odor of polypropylene composite materials.

[0015] The role of the coupling agent is to improve the compatibility between the filler and the polypropylene substrate. However, since acidic substances are also produced during the synthesis process, the heat resistance of polypropylene will be reduced. In addition, since 100% devolatilization cannot be achieved, the aldehydes, benzenes and small molecular organic substances present in it will also volatilize, which significantly increases the TVOC and odor of the polypropylene composite material.

[0016] The function of antioxidant is to delay the thermal aging of polypropylene materials.

[0017] The function of light stabilizer is to capture free radicals and delay the light aging of materials.

[0018] The role of lubricants is to increase mixing between molecular chains and improve the demoulding performance of materials.

[0019] In the polypropylene composite material of the present invention, acidic substances are generated during the extrusion granulation of polypropylene and toughening agent, and the acidic substances react with the antioxidant, so that the heat resistance of the polypropylene composite material is poor.

[0020] The alkaline inorganic salt with a specific content in the polypropylene material of the present invention can be used as an acid scavenger to remove acidic substances in the material through a neutralization reaction.

[0021] Halloysite nanotube crystals are monoclinic hydrated layered silicate minerals. The crystal structure is similar to that of kaolinite, and is also a dioctahedral structure with a 1:1 structural unit layer, but there is interlayer water between the structural unit layers, so it is also called halloysite. At 50-90°C, most of the interlayer water is lost and it becomes metamorphic halloysite, which is a homogeneous polymorph with kaolinite. Halloysite is usually dense block or soil-like; under an electron microscope, it can be seen that the crystal is in a straight or curved tubular shape, and its tubular structure can efficiently adsorb small molecules.

[0022] The alkaline inorganic salt and halloysite nanotubes in the polypropylene composite material of the present invention can be used as acid scavengers and adsorbents to remove acidic substances in the material through neutralization reaction and reduce the odor of the material. Moreover, through the synergistic effect of a limited amount of halloysite nanotubes, alkaline inorganic salts and antioxidants, the heat resistance of the material can also be improved to a certain extent.

[0023] Preferably, the alkaline inorganic salt is one or both of carbonate and bicarbonate.

[0024] The bicarbonate may be one or more of sodium bicarbonate and potassium bicarbonate.

[0025] Preferably, the alkaline inorganic salt accounts for 0.012-0.29% of the total mass of the polypropylene composite material.

[0026] In the polypropylene composite material, the content of polypropylene is not less than 60%.

[0027] Preferably, the polypropylene composite material is prepared from the following raw materials by weight:

[0028]

[0029] The devolatilizer is water, ethanol and bicarbonate;

[0030] The weight ratio of water, ethanol and bicarbonate is 1:(0.05-0.1):(0.02-0.05).

[0031] When the polypropylene composite material of the present invention is used to prepare automobile interior decoration, the addition of inorganic fillers and toughening agents can improve the strength and toughness of the polypropylene composite material. However, the catalyst residue in the toughening agent and the toughening agent itself can also produce odor and organic matter. The present invention adds a devolatilizer composed of water, ethanol and sodium bicarbonate in a specific proportion and blends it with the polypropylene matrix material, so that when the material is extruded and granulated, water can dissolve aldehydes in the melt, ethanol can dissolve benzene series in the melt, and sodium bicarbonate decomposes carbon dioxide at high temperature to quickly and effectively take out a large amount of small molecular organic matter, so that the TVOC and odor level of the polypropylene composite material are significantly reduced.

[0032] Preferably, in the devolatilizer, the weight ratio of water, ethanol and bicarbonate is 1:(0.06-0.08):(0.03-0.04).

[0033] Preferably, the average length of the halloysite nanotubes is 1-20 μm.

[0034] For example, the average length of the halloysite nanotubes may be 1 μm, 5 μm, 6 μm, 10 μm, 15 μm or 20 μm.

[0035] More preferably, the average length of the halloysite nanotubes is 6-15 μm.

[0036] Preferably, the polypropylene is homopolypropylene and / or copolymer polypropylene.

[0037] More preferably, the polypropylene is copolymerized polypropylene.

[0038] Preferably, the inorganic filler is one or more of talc, calcium carbonate, mica or basic magnesium sulfate whisker.

[0039] Preferably, the toughening agent is one or more of polyethylene (PE), ethylene-octene copolymer (POE) or hydrogenated styrene-butadiene-styrene copolymer (SEBS).

[0040] More preferably, the toughening agent is ethylene-octene copolymer (POE).

[0041] Preferably, the coupling agent is a titanate coupling agent and / or an aluminate coupling agent.

[0042] More preferably, the coupling agent is a titanate coupling agent and an aluminate coupling agent.

[0043] Optionally, the titanate coupling agent is triisostearoyl isopropyl titanate, such as TMC-981 from Tianchang Green Chemical.

[0044] Optionally, the aluminate coupling agent is isopropyl distetradecanoyloxyaluminate, for example, HY-988 from Hangzhou Jessica Chemical Co., Ltd.

[0045] Preferably, the weight ratio of the titanate coupling agent to the aluminate coupling agent is (1-3):1.

[0046] Preferably, the light stabilizer is a hindered amine and / or a benzotriazole.

[0047] More preferably, the light stabilizer is a hindered amine and a benzotriazole, and the weight ratio of the hindered amine to the benzotriazole is (1-3):1.

[0048] Optionally, the hindered amine light stabilizer is UV3808PP5 (ie, UV3853:UV2908=1:1 compound), wherein UV3853 is 2,2,6,6-tetramethyl-4-piperidinyl stearate, and UV2908 is 3,5-di-tert-butyl-4-hydroxy-benzoic acid hexadecyl ester.

[0049] Optionally, the benzotriazole light stabilizer 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole is tinuvin 326.

[0050] Preferably, the lubricant is ethylene bisstearamide and / or calcium stearate.

[0051] More preferably, the lubricant is ethylene bisstearamide (EBS) and calcium stearate, and the weight ratio of ethylene bisstearamide to calcium stearate is (0.5-2):1.

[0052] Optionally, the D50 particle size of ethylene bis stearamide is 300-600 mesh. If the particle size is too large, the processing cost of raw material production is high, and if the particle size is too small, the material is easy to bridge, resulting in unsmooth or unstable production.

[0053] Optionally, the antioxidant is one or more of hindered phenols, phosphites or thioesters.

[0054] More preferably, the antioxidant is hindered phenols, phosphites and thioesters, and the weight ratio of hindered phenols, phosphites and thioesters is (0.5-2):(0.5-2):1.

[0055] Optionally, the hindered phenol antioxidant is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], for example, Antioxidant 1010.

[0056] Optionally, the phosphite antioxidant is tris(2,4-di-tert-butylphenyl)phosphite, for example, Antioxidant 168.

[0057] Optionally, the thioester antioxidant is distearyl thiodipropionate, for example, the antioxidant DSTDP.

[0058] The present invention also provides a method for preparing a polypropylene composite material, comprising the following steps:

[0059] The components are mixed, melt-extruded and granulated by an extruder, and dried to obtain the polypropylene composite material;

[0060] The temperature of the first screw section and the second screw section of the extruder from the feeding section to the die is 15-35°C;

[0061] The vacuum degree during melt extrusion is ≤-0.05 bar.

[0062] The extruder may be a twin-screw extruder.

[0063] In the preparation method of the polypropylene composite material of the present invention, the temperature of the first section screw and the second section screw of the extruder from the feeding section to the die head is 15-35°C, that is, the processing temperature of the first section and the second section is maintained at room temperature to prevent the heating temperature from exceeding 100°C, resulting in premature vaporization and decomposition of water and ethanol in the devolatilizer, thereby reducing the devolatilization effect. This method is effective in preparing low-odor and low-volatile automotive interior materials, and can significantly improve the odor and volatiles of the composite material. Water can dissolve aldehydes in the melt, ethanol can dissolve benzene series in the melt, and sodium bicarbonate decomposes carbon dioxide at high temperature to quickly and effectively bring out a large amount of small molecular organic matter, so that the diffusion of the composite material is significantly reduced.

[0064] Double vacuum design, and the vacuum degree requirement is ≤-0.05bar. A higher vacuum degree is conducive to the clean extraction of water vapor and small molecular volatiles, thus improving the devolatilization effect.

[0065] The polypropylene composite material prepared by the present invention has low sourness, low odor and TVOC, and good heat resistance, and can be widely used in the preparation of plastic products. The present invention especially protects the application of the polypropylene composite material in the preparation of automobile interiors.

[0066] The automobile interior can be one or more of an automobile door interior panel, an instrument panel upper cover, a pillar, a seat guard plate, a glove box or a central control housing.

[0067] Compared with the prior art, the present invention has the following beneficial effects:

[0068] The polypropylene composite material of the present invention comprises polypropylene, inorganic filler, toughening agent, coupling agent, antioxidant, light stabilizer, lubricant, halloysite nanotubes and alkaline inorganic salt. The alkaline inorganic salt and halloysite nanotubes in the polypropylene composite material of the present invention can be used as acid scavengers and adsorbents to remove acidic substances in the material through neutralization reaction and reduce the odor of the material. Moreover, through the synergistic effect of the halloysite nanotubes, alkaline inorganic salts and antioxidants, the heat resistance of the material can also be improved to a certain extent. DETAILED DESCRIPTION

[0069] The present invention is further described below in conjunction with specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0070] Polypropylene:

[0071] Copolymer PP Model: EP548R Manufacturer: CNOOC Shell;

[0072] Homopolymer PP Model: N-Z30S Manufacturer: Sinopec Maoming Petrochemical;

[0073] Inorganic fillers:

[0074] Calcium carbonate model: LD-1000C Manufacturer: Lida Superfine;

[0075] Mica powder model: GH-2 Manufacturer: Chuzhou Ge Rui;

[0076] Basic magnesium sulfate whisker Model: WS-3D Manufacturer: Yingkou Weisker;

[0077] Toughening agent:

[0078] Polyethylene PE Model: 3518PA Manufacturer: ExxonMobil;

[0079] Ethylene-octene copolymer POE Model: 8150 Manufacturer: Dow Chemical;

[0080] Hydrogenated styrene-butadiene-styrene copolymer SEBS Model: G1657 Manufacturer: Kraton, USA; Coupling agent:

[0081] Titanate coupling agents are commercially available and the same one was used in all examples and comparative examples;

[0082] Aluminate coupling agents are commercially available and the same one was used in all examples and comparative examples;

[0083] Antioxidants:

[0084] Hindered phenols are commercially available and the same one was used in all examples and comparative examples;

[0085] Phosphites are commercially available and the same one was used in all examples and comparative examples;

[0086] Thioesters are commercially available and the same one was used in all examples and comparative examples;

[0087] Light stabilizer:

[0088] Hindered amines are commercially available and the same one was used in all examples and comparative examples;

[0089] Benzotriazoles are commercially available and the same one was used in all examples and comparative examples;

[0090] Lubricant:

[0091] Ethylene bisstearamide is commercially available and the same one was used in all examples and comparative examples;

[0092] Calcium stearate is commercially available and the same one was used in all examples and comparative examples;

[0093] Liquid distilled water is commercially available and the same was used in all examples and comparative examples;

[0094] Anhydrous ethanol is commercially available and the same one was used in all examples and comparative examples;

[0095] Sodium bicarbonate is commercially available and the same one was used in all examples and comparative examples;

[0096] Halloysite Nanotubes:

[0097] Halloysite nanotubes 1, average length 16-20um, manufacturer: Jinfa homemade;

[0098] Halloysite nanotubes 2, average length 11-15um, manufacturer: Jinfa homemade;

[0099] Halloysite nanotubes 3, average length 6-10um, manufacturer: Jinfa homemade;

[0100] Halloysite nanotubes 4, average length 1-5um, manufacturer: Jinfa homemade;

[0101] Homemade method of halloysite nanotubes: Purchase halloysite ore on the market, grind it with a crusher, and obtain halloysite nanotubes of different lengths according to the grinding time.

[0102] Examples 1 to 10

[0103] A polypropylene composite material is prepared from the following raw materials by weight: polypropylene; inorganic filler; toughening agent; coupling agent; antioxidant; light stabilizer; lubricant; halloysite nanotubes and devolatilizer;

[0104] Wherein, the devolatilizer is water, ethanol and sodium bicarbonate.

[0105] The specific content of each component is shown in Table 1 below.

[0106] Table 1 Composition of polypropylene composite materials in various embodiments (by weight)

[0107]

[0108]

[0109] Table 1

[0110]

[0111]

[0112] The preparation method of the polypropylene composite material comprises the following steps:

[0113] First, weigh polypropylene, toughening agent, coupling agent, and halloysite nanotubes and mix them in a high-speed mixer for 3 to 5 minutes, wherein the speed of the high-speed mixer is 200 to 300 rpm; then weigh devolatilizer and slowly add it from the top liquid feed of the high-speed mixer; then weigh inorganic filler and add it to the high-speed mixer for mixing for 3 to 5 minutes, wherein the speed of the high-speed mixer is 200 to 300 rpm; finally weigh antioxidant, light stabilizer, and lubricant and add them to the high-speed mixer for mixing for 3 to 5 minutes, wherein the speed of the high-speed mixer is 200 to 300 rpm. Add the mixed particles into a twin-screw extruder for melt extrusion, granulation, drying, cooling, and packaging. The temperature of the twin-screw extruder from the feeding section to the die is 15-35°C (not heated) in the first section, 15-35°C (not heated) in the second section, 170°C in the third section, 180°C in the fourth section, 200°C in the fifth section, 210°C in the sixth section, 215°C in the seventh section, 215°C in the eighth section, 215°C in the ninth section, and 210°C in the tenth section. Double vacuum extraction design, and the vacuum degree requirement is ≤-0.05bar.

[0114] Comparative Examples 1 to 4

[0115] A polypropylene composite material is prepared from the following raw materials by weight: polypropylene; inorganic filler; toughening agent; coupling agent; antioxidant; light stabilizer; lubricant; halloysite nanotubes and devolatilizer;

[0116] Wherein, the devolatilizer is water, ethanol and sodium bicarbonate.

[0117] The specific content of each component is shown in Table 2 below.

[0118] Table 2 Composition of polypropylene composite materials of each comparative example (by weight)

[0119]

[0120]

[0121] The preparation method of the polypropylene composite material is the same as that in the embodiment, and will not be described again here.

[0122] Results

[0123] The polypropylene composite materials of each embodiment and comparative example were tested according to the following method:

[0124] (1) Odor: The test was conducted in accordance with Shanghai Volkswagen's PV3900-2019 "Odor Test for Components in Automobile Compartments": 1. Place 20 g of granulated material in a 1 L odor test bottle; 2. Place the granulated material in an 80 °C oven for 2 h, take it out and wait for the bottle to cool to 60 °C before evaluating the odor; 3. Odor evaluation method: The odor evaluation was calibrated according to the odor level given in Table 3.

[0125] Table 3 Odor levels

[0126] grade Odor description 1 Can't feel 2 Feel it, not disturbing 3 Noticeable but not intrusive 4 Disturb 5 Strong dislike 6 Intolerable

[0127] (2) Volatile organic matter: Total carbon content (TVOC) is tested in accordance with Shanghai Volkswagen’s PV3341-1995 “Emission of Organic Compounds” standard, with the unit being μgC / g.

[0128] (3) Heat aging time: The test standard is GB / T 7141-2008, and the test condition is 120°C. The longer the heat aging time, the better the heat aging resistance.

[0129] (4) Sourness: The test standard is based on PV3900-2019, the test method is 1L bottle method, and the test condition is 80℃ / 2h. (Judgment criteria: Level 1---no sourness; Level 2---mild sourness; Level 3---moderate sourness; Level 4---severe sourness)

[0130] (5) Atomization: The test standard is PV3015-1994, the test method is atomization cup test, 80mm disc, and the test condition is 100℃ / 16h. The lower the atomization value, the better the material's atomization resistance, which means the lower the sour taste.

[0131] The specific test results of the polypropylene composite materials of each embodiment and comparative example are described in Table 4 below:

[0132] Table 4

[0133]

[0134] It can be clearly seen from the above embodiments that the polypropylene composite material of the present invention has a TVOC of ≤12 ugC / g, which can be as low as 3.1 ugC / g, an odor level of ≤2.7, which can be as low as 2, a heat aging time at 120°C of greater than 4687 h, which can be as high as 5478 h, and atomization of less than 0.86 mg / g, which can be as low as 0.21 mg / g.

[0135] It can be seen from Comparative Example 1 that without the addition of halloysite nanotubes, the TVOC of the material is too high.

[0136] It can be seen from Comparative Example 2 that although excessive addition of halloysite nanotubes is beneficial to reducing the TVOC of the material, it will lead to a decrease in the thermal aging performance of the material.

[0137] It can be seen from Comparative Example 3 that without adding alkaline inorganic salt, the odor of the material is too strong and the atomization is too poor.

[0138] It can be seen from Comparative Example 4 that there is too much alkaline inorganic salt, and the atomization and thermal aging of the material are too poor.

[0139] It can be seen from Example 1, Example 5 and Example 6 that the weight ratio of water, ethanol and bicarbonate is 1:(0.06-0.08):(0.03-0.04), which has a better effect.

[0140] It can be seen from Example 1 and Examples 7-9 that the length of the halloysite nanotubes is 6 to 15 μm, which is more conducive to achieving a balance between odor and heat aging performance.

[0141] It can be seen from Example 1 and Example 10 that the toughening agent is SEBS, and the odor is lower, mainly because SEBS has a lower crystallinity and can absorb more volatiles.

[0142] 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 polypropylene composite material, characterized in that: By weight, it includes the following components: The devolatilizer is water, ethanol and bicarbonate; The weight ratio of water, ethanol and bicarbonate is 1:(0.05-0.1):(0.02-0.05).

2. The polypropylene composite material according to claim 1, characterized in that: The product is prepared from the following raw materials by weight: The devolatilizer is water, ethanol and bicarbonate; The weight ratio of water, ethanol and bicarbonate is 1:(0.05-0.1):(0.02-0.05).

3. The polypropylene composite material according to claim 1, characterized in that: The average length of the halloysite nanotubes is 1-20 μm.

4. The polypropylene composite material according to claim 3, characterized in that: The average length of the halloysite nanotubes is 6-15 μm.

5. The polypropylene composite material according to claim 1, characterized in that: The polypropylene is homopolymer polypropylene and / or copolymer polypropylene; the inorganic filler is one or more of talcum powder, calcium carbonate, mica or basic magnesium sulfate whisker.

6. The polypropylene composite material according to claim 1, characterized in that: The toughening agent is one or more of polyethylene, ethylene-octene copolymer or hydrogenated styrene-butadiene-styrene copolymer.

7. The polypropylene composite material according to claim 1, characterized in that: The coupling agent is a titanate coupling agent and / or an aluminate coupling agent; the light stabilizer is a hindered amine and / or a benzotriazole; and the lubricant is ethylene bisstearamide and / or calcium stearate.

8. The polypropylene composite material according to claim 1, characterized in that: The antioxidant is one or more of hindered phenols, phosphites or thioesters.

9. The method for preparing the polypropylene composite material according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: mixing the components, melting and extruding through an extruder, granulating, and drying to obtain the polypropylene composite material; The temperature of the first screw section and the second screw section of the extruder from the feeding section to the die is 15-35°C; The vacuum degree during melt extrusion is ≤-0.05 bar.

10. Use of the polypropylene composite material according to any one of claims 1 to 8 in the preparation of automobile interior decoration.

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