Polypropylene composition, process for its preparation and use thereof

Abstract

The application discloses a polypropylene composition and a preparation method and application thereof, and belongs to the technical field of high polymer materials. The product comprises the following components in parts by weight: polypropylene resin 59-71 parts, high-aluminum glass fiber 20-40 parts, attapulgite 2-8 parts, compatibility agent 1-3 parts, peroxide initiator 0.01-0.2 parts, and ethenyl silane crosslinking agent 0.5-1.5 parts. Since the attapulgite and the high-aluminum glass fiber composite filler are introduced into the matrix resin, and then the initiator and the crosslinking agent are compounded, the product can effectively improve the resistance of the product to external force and temperature, can guarantee that the product has sufficient rigidity and toughness, and appearance problems do not occur.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and in particular to a polypropylene composition, a preparation method and an application thereof. Background Art

[0002] Polypropylene material has excellent physical properties, chemical stability and processing performance, but under long-term stress or high temperature environment, it is extremely prone to creep, which in turn causes plastic deformation.

[0003] In automotive cooling systems, due to the frequent long-term dynamic changes in temperature and pressure, it is generally difficult to use polypropylene-based composite materials with poor creep resistance. To this end, people have tried to improve the creep phenomenon of products by adding modified materials, such as adding large doses of inorganic fillers to reduce the dynamic fluidity of the product, or adding nano-nucleating agents to increase the crystallinity of polypropylene resin. However, such practices may lead to an imbalance in the rigidity and toughness of the product, making it difficult to use in automotive parts, and may even cause obvious appearance problems. Summary of the Invention

[0004] Based on the defects of the existing technology, the purpose of the present invention is to provide a polypropylene composition, which introduces attapulgite and high-aluminum glass fiber composite filler into the matrix resin, and then compounded with an initiator and a cross-linking agent. The product is based on the network structure of the filler as support and the strong force of the polypropylene molecular weight, which can not only effectively improve the product's resistance to external forces and temperature, but also ensure that the product has sufficient rigidity and toughness, and will not have appearance problems.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A polypropylene composition comprising the following components in parts by weight:

[0007] 59-71 parts of polypropylene resin, 20-40 parts of high-aluminum glass fiber, 2-8 parts of attapulgite, 1-3 parts of compatibilizer, 0.01-0.2 parts of peroxide initiator, and 0.5-1.5 parts of vinyl silane crosslinking agent;

[0008] The alumina content of the high-aluminum glass fiber is ≥30 wt%.

[0009] Preferably, the peroxide initiator includes at least one of dibenzoyl peroxide, dodecyl peroxide, and dicumyl peroxide.

[0010] In the technical solution of the present invention, in order to improve the creep resistance of the product while ensuring that the mechanical strength of the product can be maintained at a relatively good level, the inventor introduced attapulgite and high-aluminum glass fiber into the polypropylene resin matrix. Attapulgite has high dispersibility and a special needle-rod structure. When compounded with glass fiber, it will form a composite structure similar to a fiber mesh. This structure has high mechanical capacity and can provide a supporting skeleton in multiple force directions with high force balance. High-aluminum glass fiber has ideal mechanical strength and can improve the creep resistance of the product without the introduction of a large dose. At the same time, this glass fiber will not easily break or fracture after processing or when subjected to force, which can ensure the rigidity of the product. On the other hand, the peroxide initiator will decompose into free radicals under heating. Taking dibenzoyl peroxide as an example, in polypropylene When in the resin matrix, it will decompose to generate benzoyl radicals and phenyl radicals after heating. This highly active free radical will attack the hydrogen atoms on the polypropylene molecular chain to form polypropylene macromolecular chain free radicals. At this time, this polypropylene macromolecular chain free radical will act on the vinyl double bond of the vinyl silane crosslinker to form a free radical intermediate, and the crosslinker in the free body will further undergo hydrolysis or condensation reaction to produce silanol groups. In the condensation reaction, Si-O-Si bonds are formed through the dehydration reaction between Si-OH groups. These Si-O-Si bonds rivet the polypropylene molecular chains together, so that the originally loose polypropylene molecular chains form a dense cross-linked network, which not only improves the melt strength, deformation resistance and anti-slip properties of the polypropylene resin matrix, but also can effectively bond to the filler skeleton, ultimately achieving ideal creep resistance.

[0011] However, if other fillers are used in combination with glass fiber, the supporting strength of the filler skeleton cannot be guaranteed. If ordinary glass fiber is used to construct the skeleton, not only may the mechanical strength of the product be insufficient, but its creep resistance will also be low. Inappropriate filler compounding may even lead to appearance problems. Furthermore, the initiator and crosslinker are key to whether the polypropylene resin can form a dense body. If their types are changed or missing, the creep resistance of the product will be severely weakened.

[0012] Preferably, the polypropylene composition comprises the following components in parts by weight:

[0013] 60-70 parts of polypropylene resin, 23-38 parts of high-aluminum glass fiber, 4-6 parts of attapulgite, 1-3 parts of compatibilizer, 0.01-0.2 parts of peroxide initiator, and 0.5-1.5 parts of vinyl silane crosslinking agent.

[0014] More preferably, the mass content of the polypropylene resin in the polypropylene composition is ≥50 wt%.

[0015] Preferably, the alumina content of the high-aluminum glass fiber is 30-32 wt%.

[0016] More preferably, the high-aluminum glass fiber has an average length of 2 to 5 mm and an average diameter of 7 to 10 μm.

[0017] More preferably, the alumina content, average length and average diameter of the high-aluminum glass fiber are tested as follows: the glass fiber is uniformly dispersed in water, the length of the glass fiber is tested using a two-dimensional element, the glass fiber is observed using a scanning electron microscope and the diameter of the glass fiber is confirmed using mapping software, the number of glass fibers tested is not less than 50, and the test results are averaged; the alumina content of the glass fiber is determined with reference to GB / T 1549-2008.

[0018] More preferably, the vinyl silane crosslinking agent is a vinyl silane coupling agent;

[0019] More preferably, the vinyl silane coupling agent includes at least one of vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltri(β-methoxyethoxy)silane.

[0020] Preferably, the average length of the attapulgite is 0.5 to 5 μm.

[0021] More preferably, the average length of the attapulgite is in the range of one or any two of 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, and 5 μm.

[0022] Preferably, the average diameter of the attapulgite is 10 to 30 nm.

[0023] More preferably, the test method for the average particle size of the attapulgite is: uniformly disperse the attapulgite in water, use a two-dimensional element to test the length of the attapulgite, observe the attapulgite using a scanning electron microscope and use mapping software to confirm the diameter of the attapulgite, test no less than 50 attapulgites, and take the average value of the test results.

[0024] Preferably, the ratio of the average length (μm) of the high-aluminum glass fiber to the average length (μm) of the attapulgite is (1500-5000):1;

[0025] More preferably, the ratio of the average length (μm) of the high-aluminum glass fiber to the average length (μm) of the attapulgite is (2000-3500):1.

[0026] As mentioned above, high-aluminum glass fiber and attapulgite will form a stacked network structure after compounding, and under the action of initiator and cross-linker, polypropylene resin will further cross-link on the network structure, thereby forming a dense and multi-directionally resistant composite. When the glass fiber as the main skeleton and the attapulgite as the filling component are of different sizes, the looseness of the network formed will also change, which in turn affects the mechanical properties and creep resistance of the product. Under the above-mentioned preferred ratio, the riveting effect of high-aluminum glass fiber and attapulgite is the best, and the network structure is the most uniform. In particular, when the initiator and cross-linker interact with polypropylene, it will not cause the problem of attapulgite agglomeration, and the comprehensive performance of the product is the best.

[0027] More preferably, the average length of the attapulgite is 1 to 2 μm.

[0028] More preferably, the initiator is dicumyl peroxide, and the cross-linking agent is vinyltrimethoxysilane.

[0029] When this cross-linking auxiliary agent system is selected, the prepared composite polypropylene composition has the best creep resistance.

[0030] Preferably, the polypropylene resin has a melt flow rate of 10 to 80 g / 10 min at 230° C. and a load of 2.16 kg according to ISO 1133-2011.

[0031] Preferably, the polypropylene composition further comprises a compatibilizer.

[0032] More preferably, the weight portion of the compatibilizer is 1 to 3 parts.

[0033] More preferably, the compatibilizer is maleic anhydride grafted polypropylene, and the grafting rate is 0.8-1.5%.

[0034] The grafting rate of maleic anhydride can be determined by infrared spectroscopy: a sample of fixed thickness is tested using a Fourier transform infrared spectrometer to obtain characteristic absorption peaks of the infrared spectrum, and the grafting rate of maleic anhydride can be calculated by comparing the ratio of the carbonyl and methylene absorption intensities.

[0035] Preferably, the polypropylene composition further comprises a lubricant.

[0036] More preferably, the weight portion of the lubricant is 0.1 to 0.5 parts.

[0037] More preferably, the lubricant is stearate.

[0038] Preferably, the polypropylene composition further comprises an antioxidant.

[0039] More preferably, the weight portion of the antioxidant is 0.1 to 0.5 parts.

[0040] More preferably, the antioxidant is at least one of a hindered phenol antioxidant and a phosphite antioxidant.

[0041] More preferably, the antioxidant is a mixture of a hindered phenol antioxidant and a phosphite antioxidant, and the mass ratio of the two is (0.8-1.2): (1.8-2.2).

[0042] It should be noted that, based on actual product needs, those skilled in the art can appropriately introduce some components commonly introduced into polypropylene products without affecting product performance, such as antioxidants to improve the product's conventional oxidation resistance, lubricants to improve the product's processing performance, etc., and there is no need to specifically limit the types of components.

[0043] Another object of the present invention is to provide a method for preparing the polypropylene composition, comprising the following steps:

[0044] The components are added into a screw extruder for melt extrusion and granulation to obtain the polypropylene composition.

[0045] Preferably, the heating temperature of the screw extruder is 180-220° C., and the screw speed is 400-600 rpm.

[0046] The preparation method of the polypropylene composition of the present invention is simple, has low requirements on equipment, and can realize industrial-scale production.

[0047] Another object of the present invention is to provide use of the polypropylene composition in the preparation of automotive cooling system parts.

[0048] In automotive cooling systems, most components, except for metal connecting components and internal protective parts, are made of plastic. Due to the working mechanism of the system, metal connecting components often transfer heat to plastic components, causing them to be at high temperatures for a long time. In addition, metal components have the effect of thermal expansion and contraction. Therefore, some plastic components are often subjected to external pressure, resulting in obvious creep deformation. The polypropylene composition described in the technical solution of the present invention, while ensuring the use of basic mechanical properties, introduces specific functional additives and composite fillers, so that the creep resistance of the overall product is greatly improved, and it can maintain relative stability under high temperature and high pressure without obvious appearance problems. Therefore, it is very suitable for application in automotive cooling system components.

[0049] Preferably, the automobile cooling system components include an inner lining heat sink, a heat insulation sleeve, an exhaust fan, and metal buckles.

[0050] The beneficial effect of the present invention is that the present invention provides a polypropylene composition, which introduces attapulgite and high-aluminum glass fiber composite filler into the matrix resin, and then compounded with an initiator and a cross-linking agent, so that the product is based on the network structure of the filler as support and the strong force of the polypropylene molecular weight, which can not only effectively improve the product's resistance to external force and temperature, but also ensure that the product has sufficient rigidity and toughness, and will not have appearance problems. DETAILED DESCRIPTION

[0051] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments and comparative examples. Its purpose is to understand the content of the present invention in detail, rather than to limit the present invention. All other embodiments obtained by those of ordinary skill in the art without making creative work premise belong to the protection scope of the present invention. The experimental reagents and instruments involved in the implementation of the present invention are all commonly used ordinary reagents and instruments unless otherwise specified.

[0052] Examples 1 to 11

[0053] An embodiment of a polypropylene composition, a preparation method thereof, and an application thereof according to the present invention is provided. The components of the polypropylene composition are shown in Table 1.

[0054] The preparation method of the polypropylene composition comprises the following steps:

[0055] The components are mixed uniformly, and then melt-extruded and granulated in a screw extruder to obtain the polypropylene composition.

[0056] When the components are melt-extruded, the temperature zones of the twin-screw extruder are set to 180°C in zone 1, 180°C in zone 2, 180°C in zone 3, 180°C in zone 4, 180°C in zone 5, 180°C in zone 6, 180°C in zone 7, 180°C in zone 8, 180°C in zone 9, and 200°C in zone 10, the screw speed is 500 rpm, and the screw aspect ratio is 40:1.

[0057] Comparative Examples 1 to 8

[0058] The difference between the comparative examples and the examples is only in the types and proportions of the components, as shown in Table 2.

[0059] Among the components described in each embodiment and comparative example,

[0060] The polypropylene resin 1 is PP Z30S produced by Sino-Korean Petrochemical, and has a melt flow rate of 25 g / 10 min at 230° C. and a load of 2.16 kg according to ISO 1133-2011;

[0061] The polypropylene resin 2 is PP M1200HS produced by Shanghai Petrochemical, and has a melt flow rate of 12 g / 10 min at 230° C. and a load of 2.16 kg according to ISO 1133-2011;

[0062] The high-aluminum glass fiber 1 is Advantex 149H produced by Owens Corning, with an alumina content of 30 wt%, an average length of 4 mm, and an average diameter of 8 μm;

[0063] The high-aluminum glass fiber 2 is Advantex 248 produced by Owens Corning, with an alumina content of 32 wt%, an average length of 3 mm, and an average diameter of 9 μm;

[0064] The glass fiber is ECS301HP-3-H produced by Chongqing Fiberglass, with an alumina content of 25wt%, an average length of 3mm, and an average diameter of 9μm;

[0065] The talc powder is TYT-777A produced by Liaoning Haicheng Tianyuan Chemical Co., Ltd., and the average particle size after screening is 8 μm;

[0066] The attapulgite 1 to 5 are obtained by screening and grading TS003 produced by Zhongcai Attapulgite as raw material;

[0067] The attapulgite 1 has an average length of 1.2 μm and an average diameter of 18 nm after screening;

[0068] The attapulgite 2 has an average length of 1.6 μm and an average diameter of 20 nm after screening;

[0069] The attapulgite 3 has an average length of 1.9 μm and an average diameter of 20 nm after screening;

[0070] The attapulgite 4 has an average length of 0.8 μm and an average diameter of 22 nm after screening;

[0071] The attapulgite 5 has an average length of 2.6 μm and an average diameter of 19 nm after screening;

[0072] The diatomite powder is 499 product produced by Yiruishi, with an average particle size of 1.5 μm;

[0073] The compatibilizer is CA100 produced by Arkema, France, maleic anhydride grafted polypropylene, with a grafting rate of 1.1%;

[0074] The initiator 1 is dibenzoyl peroxide produced by Jinan Guochen Taifu;

[0075] The initiator 2 is dicumyl peroxide produced by Guangzhou Fangruida Chemical;

[0076] The initiator 3 is diethyldithiocarbamic acid zinc salt ZDEC produced by Shanghai Puzhen Technology;

[0077] The crosslinking agent 1 is V823925 produced by Maclean, vinyltrimethoxysilane;

[0078] The crosslinking agent 2 is KH-151 produced by Jessica, vinyl triethoxysilane;

[0079] The crosslinking agent 3 is TMPTA, trimethylolpropane triacrylate produced by Kanos Technology;

[0080] The lubricant is commercially available zinc stearate;

[0081] The antioxidant is a mixture of hindered phenol antioxidant and phosphite antioxidant produced by BASF: antioxidant 1010 and antioxidant 168 in a mass ratio of 1:2.

[0082] Unless otherwise specified, the components and raw materials used in the examples and comparative examples of the present invention are all commercially available raw materials, and the components and raw materials used in each parallel experiment are all of the same kind.

[0083] Table 1

[0084]

[0085] Table 2

[0086] Component weight parts Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Comparative Example 8 Polypropylene resin 1 65 65 65 65 65 65 65 65 High Aluminum Fiberglass 1 35 30 30 30 30 30 fiberglass 30 talcum powder 30 Compatibilizer 2 2 2 2 2 2 2 2 Attapulgite 1 5 5 5 5 5 5 diatomite 5 Initiator 1 0.1 0.1 0.1 0.1 0.1 0.1 Initiator 3 0.1 Crosslinker 1 1 1 1 1 1 1 Crosslinker 3 1 lubricant 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 antioxidants 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3

[0087] In order to verify the performance of the polypropylene composition of the present invention, the products prepared in each embodiment and comparative example were subjected to the following performance tests. The specific steps are as follows:

[0088] (1) Bending strength test: Each product was injection molded into a 150*10*4 mm test square plate and tested according to the ISO 527-2-2012 test standard at a test speed of 50 mm / min;

[0089] (2) Izod notched impact strength test: Each product was injection molded into a test square plate of 80*10*4 mm and tested according to the ISO180 / 1eA-2010 test standard, A-type notch;

[0090] (3) Creep resistance test: The test was conducted in accordance with GB / T 11546.2-2022. Each product was injection molded into a test square plate of 80*10*4mm with a span of 64mm. The bending load was set at 75% of the bending strength of the specimen. The test temperature was 120°C and the conditioning time was 24h. The creep resistance of the specimen was evaluated by measuring the time it took for the specimen to reach the predetermined bending strain value (1.5 times the thickness of the specimen) under a constant load. Under the same conditions, the longer the time, the better the creep resistance of the product.

[0091] (4) Appearance performance test: Each product is injection molded into a test square plate of 80*10*4mm, and the surface is observed for defects such as floating fibers, particles, and depressions.

[0092] The test results are shown in Tables 3 and 4.

[0093] Table 3

[0094]

[0095] Table 4

[0096]

[0097] It can be seen from Table 3 and Table 4 that the polypropylene composition of the present invention can achieve a high level of rigidity and toughness (flexural strength can reach more than 245MPa, and Izod notched impact strength can reach 18KJ / m 2 More than), its creep resistance is significantly improved, and the creep time can reach more than 25h. The main reason is the design of its inorganic filler composite network skeleton and the densification design of polypropylene resin under the action of initiator and cross-linking agent. At the same time, under the said design, the product has no obvious appearance problems and the overall performance is excellent. According to Example 1 and Examples 5 to 8, it can be seen that when designing the composite inorganic filler network skeleton, the size of high-aluminum glass fiber and attapulgite has a certain influence on its skeleton structure, density and uniformity. When the ratio of the average length (μm) of high-aluminum glass fiber to the average length (μm) of attapulgite is within the range of (2000 to 3500): 1, the creep resistance time of the product is longer, the bending strength and notched impact strength are also better, and the overall performance is better. On the other hand, for the densification design of polypropylene resin, as can be seen in Examples 1 and Examples 9 to 11, when diisopropylbenzene peroxide and vinyltrimethoxysilane are preferably matched, the overall performance of the product is better.

[0098] In contrast, the product described in Comparative Example 1 only introduced high-aluminum glass fiber when constructing the inorganic filler skeleton. It cannot effectively cross-link with the polypropylene resin and has insufficient multi-directional resistance. Therefore, the mechanical properties and creep resistance of the product are not good. In Comparative Example 2, the attapulgite is replaced with conventional small-sized filler diatomaceous earth. Obviously, it does not form an ideal skeleton structure with the high-aluminum glass fiber, and the creep resistance of the product is poor. In Comparative Example 3, the high-aluminum glass fiber is replaced with ordinary glass fiber. Due to its poor mechanical strength, it not only cannot provide sufficient basic mechanical properties for the product when used as the main body of the skeleton, but also has insufficient riveting strength for the resin. The product has a high degree of deformation and creep. The product of Comparative Example 4 uses a talcum powder system and attapulgite, which is also a very common polypropylene filler system at present. However, this system cannot effectively achieve high dispersibility and high mechanical strength after the polypropylene resin is initiating and cross-linking, and even has appearance problems. Therefore, it is obviously not applicable to automobile cooling systems. It can be seen from Comparative Examples 5 to 8 that, in addition to the network skeleton, if the polypropylene resin is not properly initiated and cross-linked, the product still cannot achieve high creep resistance. In fact, there is a significant synergistic effect between the organic and inorganic systems of the product.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A polypropylene composition, characterized in that The composition comprises the following components in parts by weight: 59-71 parts of polypropylene resin, 20-40 parts of high-aluminum glass fiber, 2-8 parts of attapulgite, 1-3 parts of compatibilizer, 0.01-0.2 parts of peroxide initiator, and 0.5-1.5 parts of vinyl silane crosslinking agent; The alumina content of the high-aluminum glass fiber is ≥30 wt%.

2. The polypropylene composition according to claim 1, wherein The peroxide initiator includes at least one of dibenzoyl peroxide, dodecyl peroxide, and dicumyl peroxide; the vinyl silane crosslinking agent is a vinyl silane coupling agent; the vinyl silane coupling agent includes at least one of vinyl trimethoxy silane, vinyl triethoxy silane, and vinyl tris (β-methoxyethoxy) silane.

3. The polypropylene composition according to claim 1, wherein The alumina content of the high-aluminum glass fiber is 30-32 wt %; the average length of the high-aluminum glass fiber is 2-5 mm, and the average diameter is 7-10 μm.

4. The polypropylene composition according to claim 1, wherein The average length of the attapulgite is 0.5 to 5 μm; the average diameter of the attapulgite is 10 to 30 nm.

5. The polypropylene composition according to claim 3 or 4, wherein: The ratio of the average length of the high-aluminum glass fiber to the average length of the attapulgite is (1500-5000):

1.

6. The polypropylene composition according to claim 1, wherein The polypropylene resin has a melt flow rate of 10 to 80 g / 10 min at 230° C. and a load of 2.16 kg according to ISO 1133-2011.

7. The polypropylene composition according to claim 1, wherein The components of the polypropylene composition further include a compatibilizer; the components of the polypropylene composition further include a lubricant; and the components of the polypropylene composition further include an antioxidant.

8. The method for preparing the polypropylene composition according to any one of claims 1 to 7, wherein: The following steps are involved: The components are added into a screw extruder for melt extrusion and granulation to obtain the polypropylene composition.

9. The method for preparing the polypropylene composition according to claim 8, wherein: The heating temperature of the screw extruder is 80-220° C., and the screw speed is 400-600 rpm.

10. Use of the polypropylene composition according to any one of claims 1 to 7 in the preparation of automotive cooling system parts.

11. The use according to claim 10, characterized in that The automobile cooling system components include an inner lining heat sink, a heat insulation sleeve, an exhaust fan, and metal buckles.

12. An automobile cooling system component, characterized in that: The polypropylene composition comprises the polypropylene composition according to any one of claims 1 to 7.

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