A flame retardant and weather resistant polypropylene composite material and its preparation method and application

Abstract

The present invention belongs to the technical field of polymer materials, and discloses a flame-retardant and weather-resistant polypropylene composite material, a preparation method and an application thereof. The flame-retardant and weather-resistant polypropylene composite material of the present invention comprises the following components by weight: 1 to 32 parts of homopolymer polypropylene; 20 to 60 parts of copolymer polypropylene, 15 to 18 parts of bromine flame retardant, 5 to 6 parts of antimony trioxide, 15 to 25 parts of talcum powder, 0.2 to 1 part of carbon black, and 0.1 to 1.5 parts of auxiliary agent. The composite material prepared by the present invention has excellent weather resistance, flame retardant properties, mechanical properties and low cost. It can be used to prepare products such as parts that are exposed to direct sunlight for a long time.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, and in particular to a flame retardant and weather resistant polypropylene composite material and a preparation method and application thereof. Background Art

[0002] Polypropylene is a general-purpose plastic with the advantages of high melting point, low density, good chemical stability, easy recycling, and low price. It has broad application prospects in the fields of automotive interiors. Since vehicles are exposed to sunlight for a long time during use, their interior parts need to have excellent flame retardant, weather resistance and mechanical properties. In the prior art, halogen-free flame retardant polypropylene materials have excellent flame retardant and weather resistance, but poor mechanical and processing properties. Brominated flame retardant polypropylene materials have excellent flame retardant and mechanical properties, but poor weather resistance. The poor weather resistance of brominated flame retardant polypropylene is determined on the one hand by the nature of brominated flame retardants and their antagonism with weathering agents. Brominated flame retardants produce aromatic radicals and bromine radicals under conditions such as light and heat. These two free radicals will join the decomposition of peroxides produced by the photoaging process, thereby accelerating the photoaging process and causing the weather resistance of brominated flame retardant polypropylene materials to deteriorate. On the other hand, bromine radicals undergo hydrogen abstraction reaction with polypropylene molecular chains to generate hydrobromic acid, which further reacts with light stabilizers to generate ammonium salts, consuming the light stabilizers while inhibiting the formation of nitro radicals and the effect of weathering agents.

[0003] At present, the common solution to improve the weather resistance of brominated flame-retardant polypropylene is to add a large amount of light stabilizers, ultraviolet absorbers, acid absorbers and increase the content of color powder (such as carbon black) in the material. And this type of method will eventually lead to a complicated processing process, a significant increase in material costs, and a decrease in thermal oxygen stability, and the weather resistance improvement effect of brominated flame-retardant polypropylene is not significant. Chinese patent document CN114213749A discloses a flame-retardant polypropylene material, which uses ultraviolet absorbers, light stabilizers and metal oxides as light aging components. The material composition is complex, and metal components are indirectly introduced, and the effect on the thermal oxygen stability of the material is unknown. Chinese patent document CN103275394B discloses a weather-resistant flame-retardant polypropylene composite material and a preparation method thereof, which selects carbon black as a weathering modifier, and the addition amount is 1.5-2.5wt%. Such a high content of carbon black will inevitably lead to a decrease in the processability of the polypropylene composite material, and at the same time, it will cause the thermal stability of the polypropylene composite material to decrease. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a flame-retardant and weather-resistant polypropylene composite material with excellent weather resistance, flame retardancy, mechanical properties and low cost, as well as a preparation method and application thereof, so as to overcome the problems of poor weather resistance and complex formulation of brominated flame-retardant polypropylene in the prior art.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] In a first aspect, the present invention provides a flame retardant and weather-resistant polypropylene composite material, comprising the following components by weight: 1 to 32 parts of homopolymer polypropylene; 20 to 60 parts of copolymer polypropylene, 15 to 18 parts of brominated flame retardant, 5 to 6 parts of antimony trioxide, 15 to 25 parts of talc, 0.2 to 1 part of carbon black, and 0.1 to 1.5 parts of additives;

[0007] The particle size of the talcum powder is 3000-5000 mesh;

[0008] The ethylene-propylene rubber content in the polypropylene composite material (measured by high-temperature gel permeation chromatography) is 12% to 18%.

[0009] The present invention adopts homopolymerized polypropylene, copolymerized polypropylene, bromine flame retardant, antimony trioxide and talcum powder of specific particle size, and the components can play a synergistic role, so that the EPR content in the prepared flame-retardant and weather-resistant polypropylene composite material is 12% to 18%. Since polypropylene and EPR have a phase separation structure in the composite material, the composite material has a unique phase structure. After the composite material forms a unique phase structure, the bromine flame retardant and talcum powder are dispersed in the polypropylene phase, and antimony trioxide is dispersed in the EPR phase. Moreover, the specific EPR content forms a protective layer on the surface of the composite material, which reduces the contact between the bromine flame retardant and antimony trioxide. When ultraviolet light irradiates the surface of the composite material, antimony trioxide consumes the ultraviolet light, thereby reducing the irradiation effect of ultraviolet light on the bromine flame retardant in the polypropylene phase, reducing the decomposition of the bromine flame retardant, and also reducing the degradation effect of the bromine flame retardant on polypropylene, thereby improving the weather resistance of the composite material; the alkaline talcum powder has an adsorption effect on acidic substances such as hydrobromic acid generated by the decomposition of the bromine flame retardant, thereby improving the weather resistance of the composite material.

[0010] Among them, the content of brominated flame retardants is crucial to flame retardancy and weather resistance. When the content of brominated flame retardants is low, the flame retardancy of the composite material is poor; when the content of brominated flame retardants is high, the negative impact on weather resistance is higher, resulting in poor weather resistance of the composite material. The particle size of talcum powder also plays a role in the weather resistance of the composite material. If the particle size is too large, the specific surface area of ​​talcum powder is small, the adsorption effect on acidic substances is weak, and the effect of improving weather resistance is not obvious; if the particle size of talcum powder is too small, the specific surface area is large, and it is easier to cause the decomposition of brominated flame retardants during processing, resulting in poor weather resistance.

[0011] Moreover, carbon black has the function of UV shielding, but the higher the carbon black content, the more difficult the processing, the higher the cost, and the lower the heat aging resistance. The present invention can significantly improve the weather resistance of the composite material by adjusting the phase structure of the brominated flame retardant polypropylene with a conventional amount of carbon black added, which not only ensures that the composite material has excellent processing performance, but also avoids environmental pollution during the processing and the reduction of the heat aging resistance of the composite material.

[0012] As a preferred embodiment of the flame-retardant and weather-resistant polypropylene composite material of the present invention, the content of the copolymerized polypropylene is 32 to 60 parts.

[0013] As a preferred embodiment of the flame-retardant and weather-resistant polypropylene composite material of the present invention, the content of ethylene-propylene rubber in the copolymerized polypropylene is 15% to 40%; preferably, the content of ethylene-propylene rubber in the copolymerized polypropylene is 29% to 37.8%.

[0014] As a preferred embodiment of the flame-retardant and weather-resistant polypropylene composite material of the present invention, the brominated flame retardant is at least one of decabromodiphenylethane, tetrabromobisphenol A, octabromoether and octabromotriphenylether.

[0015] As a preferred embodiment of the flame retardant and weather resistant polypropylene composite material of the present invention, the auxiliary agent includes 0.1 to 0.3 parts of a primary antioxidant, 0.1 to 0.3 parts of an auxiliary antioxidant, and 0.2 to 0.5 parts of a light stabilizer.

[0016] As a preferred embodiment of the flame-retardant and weather-resistant polypropylene composite material of the present invention, the primary antioxidant is a hindered phenol antioxidant; the auxiliary antioxidant is a phosphite antioxidant; and the light stabilizer is a hindered amine light stabilizer.

[0017] In the flame retardant and weather resistant polypropylene composite material of the present invention, the light stabilizer has an effect of improving the weather resistance of the composite material, but the higher the content, the better. When the content exceeds 0.3 parts, the improvement of the weather resistance of the composite material enters a plateau period, and the cost of the composite material will increase.

[0018] In a second aspect, the present invention provides a method for preparing the flame retardant and weather resistant polypropylene composite material, comprising the following steps:

[0019] The components are weighed respectively, mixed, melted, extruded, granulated, and cooled to obtain the product.

[0020] As a preferred embodiment of the preparation method of the present invention, the mixing is carried out at a rotation speed of 200 r / min to 500 r / min for 5 min to 8 min.

[0021] In a third aspect, the present invention applies the flame-retardant and weather-resistant polypropylene composite material to parts that are exposed to direct sunlight for a long time, such as automotive interior and exterior parts.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The brominated flame retardant and weather-resistant polypropylene composite material of the present invention comprises homopolymerized polypropylene, copolymerized polypropylene, brominated flame retardant, antimony trioxide, talcum powder, carbon black and additives. The present invention effectively regulates the phase structure of polypropylene and EPR in the composite material by regulating the content of the polypropylene matrix, and then through the synergistic effect between the components, under the action of conventional amounts of brominated flame retardant and antimony trioxide, a polypropylene composite material with excellent flame retardant, weather-resistant and mechanical properties is obtained, and the formula composition is simple. The prepared composite material meets the UL94 vertical burning test V-0 (strip thickness 1.5mm) level, SAE J24121240kJ / m 2 After light aging test, △E≤1.5, flexural modulus≥2200MPa, notched impact≥4.0kJ / m 2 . BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a transmission electron microscope image of the cross-sectional morphology of the flame-retardant and weather-resistant polypropylene composite material of Comparative Example 4;

[0025] Figure 2 This is a scanning electron microscope image of the cross-sectional surface etching morphology of the flame-retardant and weather-resistant polypropylene composite material of Comparative Example 4;

[0026] Figure 3 This is a transmission electron microscope image of the cross-sectional morphology of the flame-retardant and weather-resistant polypropylene composite material of Comparative Example 5;

[0027] Figure 4 This is a scanning electron microscope image of the cross-sectional surface etching morphology of the flame-retardant and weather-resistant polypropylene composite material of Comparative Example 5. DETAILED DESCRIPTION

[0028] In order to better illustrate the purpose, technical scheme and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments. It should be understood by those skilled in the art that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. The ethylene propylene rubber (EPR) content (in mass percentage) in the material is measured by high temperature gel permeation chromatography.

[0029] 1. The raw materials used in the embodiments and comparative examples are described as follows, but are not limited to these materials:

[0030] (1) Homopolymer polypropylene

[0031] PP HP500N, purchased from CNOOC and Shell Petrochemical Co., Ltd.;

[0032] (2) Copolymer polypropylene

[0033] PP EP548R, EPR content: 18%, purchased from CNOOC Shell Petrochemical Co., Ltd.;

[0034] PP K9017, EPR content: 20%, purchased from Taiwan Chemical Fiber Co., Ltd.;

[0035] PP 8285E1, EPR content: 29%, purchased from ExxonMobil;

[0036] PP SP179, EPR content: 37.8%, purchased from Taiwan Chemical Fiber Co., Ltd.;

[0037] PP LH-KA30, EPR content: 40%, purchased from Lihe Zhixin New Materials Technology Co., Ltd.

[0038] (3) Flame retardant

[0039] Decabromodiphenylethane, SAYTEX 8010, was purchased from Albemarle, USA;

[0040] Tetrabromobisphenol A, FR-1524, purchased from the Dead Sea, Israel;

[0041] Octabromoether, XZ-6800, was purchased from Shandong Brothers Technology Co., Ltd.;

[0042] Octabromo-S-ether, purchased from Shouguang Ocean Chemical Co., Ltd.;

[0043] Antimony trioxide, S-05N, was purchased from Changde Chenzhou Antimony Products Co., Ltd.

[0044] (4) Talc:

[0045] T01, particle size 1000 mesh, purchased from Dandong Tianci Flame Retardant Material Technology Co., Ltd.;

[0046] TYT-777A, particle size 3000 mesh, purchased from Haicheng Tianyuan Chemical Co., Ltd.;

[0047] HTPultra5L, particle size 5000 mesh, purchased from Guangzhou Xijia Chemical Co., Ltd.;

[0048] HF-6000A, particle size 6000 mesh, was purchased from Changzhou Rongao Chemical New Materials Co., Ltd.

[0049] (5) Carbon black

[0050] M717, purchased from Cabot Chemical Co., Ltd.;

[0051] (6) Antioxidants

[0052] Primary antioxidant: hindered phenol antioxidant Y-001, purchased from Yingkou Fengguang Chemical Co., Ltd.;

[0053] Auxiliary antioxidant: phosphite antioxidant Y-002, purchased from Yingkou Fengguang Chemical Co., Ltd.

[0054] (7) Light stabilizer

[0055] Hindered amine composite light stabilizer, T-81, was purchased from Beijing Tiangang Additive Co., Ltd.

[0056] The components of the flame-retardant and weather-resistant polypropylene composite materials of Examples 1 to 11 and Comparative Examples 1 to 8 are shown in Table 1.

[0057] The preparation methods of the flame-retardant and weather-resistant polypropylene composite materials of Examples 1 to 11 and Comparative Examples 1 to 8 are as follows:

[0058] Homopolymer polypropylene, copolymer polypropylene, brominated flame retardant, antimony trioxide, talcum powder, carbon black, primary antioxidant, auxiliary antioxidant and light stabilizer are weighed respectively and added into a high-speed mixer for mixing at a mixing speed of 200 r / min to 500 r / min and a mixing time of 5 min to 8 min to obtain a mixture A; the mixture A is added into a twin-screw extruder for melt extrusion, and after granulation and cooling, a flame-retardant and weather-resistant polypropylene composite material is obtained.

[0059] 2. The relevant properties of the flame retardant and weather resistant polypropylene composite materials of Examples 1 to 11 and Comparative Examples 1 to 8 are as follows:

[0060] (1) Flame retardant performance test

[0061] According to the UL94 standard for plastic fire rating, the vertical burning performance of 1.5mm thick specimens was tested;

[0062] (2) Weather resistance test

[0063] The weather resistance of the sample was tested according to the SAE J2412 test standard, and the irradiation energy was 1240kJ / m 2 , the detection time is 792h;

[0064] (3) Flexural modulus test

[0065] The test was carried out in accordance with the standard "ISO 178-2019 Determination of flexural properties of plastics" with a test speed of 2mm / min;

[0066] (4) Simply supported beam notched impact strength test

[0067] The test was conducted in accordance with the standard "ISO 179 / 1eA-2010 Determination of pendulum impact properties of plastics". The flame retardancy, weather resistance, flexural modulus and notched impact test results of the flame retardant and weather resistant polypropylene composite materials of Examples 1 to 11 and Comparative Examples 1 to 8 are shown in Table 1.

[0068] Table 1 Components of composite materials (parts by weight)

[0069]

[0070] Table 1 Components of composite materials (parts by weight)

[0071]

[0072]

[0073] By comparing the flame-retardant and weather-resistant polypropylene composite materials of Examples 1 to 11 and Comparative Examples 1 to 8, it can be seen that the present invention adopts specific contents of homopolypropylene, copolymer polypropylene, bromine-based flame retardant, antimony trioxide, and talc powder with a specific particle size, which can play a synergistic role and make the prepared polypropylene composite material have excellent weather resistance (V-0), weather resistance (△E≤1.5), rigidity and toughness.

[0074] After the composite material forms a unique phase structure, the brominated flame retardant and talcum powder are dispersed in the polypropylene phase, and antimony trioxide is dispersed in the EPR phase. Moreover, the specific EPR content forms a protective layer on the surface of the composite material, which reduces the contact between the brominated flame retardant and antimony trioxide. When ultraviolet light irradiates the surface of the composite material, antimony trioxide consumes the ultraviolet light, thereby reducing the irradiation effect of ultraviolet light on the brominated flame retardant in the polypropylene phase, reducing the decomposition of the brominated flame retardant, and also reducing the degradation of the brominated flame retardant on polypropylene, thereby improving the weather resistance of the composite material; the alkaline talcum powder has an adsorption effect on acidic substances such as hydrobromic acid produced by the decomposition of the brominated flame retardant, thereby improving the weather resistance of the composite material.

[0075] Comparative Example 3 Compared with Example 4, the content of EPR in the prepared composite material is 7.9%, which is not within the range of 12% to 18%. Figure 1 This is a cross-sectional morphology of the material with an EPR content of less than 12% in comparative example 3, in which the gray spheres are EPR components, the gray flakes are talc (Talc), and the black is the flame retardant (DBDPE). The distribution size of EPR in the prepared composite material is small, polypropylene and EPR do not have a phase separation structure in the composite material, and the weather resistance of the composite material is poor. In order to further illustrate the difference in the influence of EPR content on the morphology of the material, the material was immersed in 50°C toluene, ultrasonicated for 24 hours, and etched (the EPR phase can be dissolved to form pits on the surface of the material). Figure 2 This is the morphology of the surface of the material in comparative example 3 with an EPR content below 18% after etching, with relatively few pits.

[0076] Comparative Example 4 Compared with Example 4, the content of EPR in the prepared composite material is 18.9%, which is not within the range of 12% to 18%. Figure 3 This is a cross-sectional morphology of a material with an EPR content of more than 18%. The gray spheres are EPR components, the gray flakes are talc (Talc), and the black is a flame retardant (DBDPE). The distribution size of EPR in the prepared composite material is smaller and more obvious. There is no phase separation structure between polypropylene and EPR in the composite material, resulting in a decrease in the flame retardant performance of the composite material. In order to further illustrate the difference in the effect of EPR content on the morphology of the material, the material was etched with toluene (the EPR phase can be dissolved to form pits on the surface of the material). Figure 4 This is the morphology of the surface of the material in comparative example 4 with an EPR content of more than 18% after etching. There are many pits, which can basically be connected into a piece.

[0077] Therefore, it can be considered that after the EPR content reaches 12% to 18%, a protective layer with EPR as the main component is formed on the surface of the prepared composite material. In order to prove that the weathering agent is dispersed in EPR, the composite material prepared in Example 4 is etched with toluene, and the EPR solution after toluene etching is dried at 80°C to constant weight, the main components of the dried product are tested, and the infrared spectrum is compared with the individual components in the material formula. It is found that the main components of the dried product are EPR and weathering agent. It is proved that the weathering agent is mainly distributed in EPR. When the EPR content reaches 12% to 18%, it can effectively absorb ultraviolet rays, and the material is protected from ultraviolet radiation and decomposition of the flame retardant.

[0078] Comparing Comparative Example 1 with Example 2, it can be seen that the EPR content of the composite material is lower than 12%, and the weather resistance of the composite material is poor.

[0079] Compared with Example 4, in Comparative Example 2, the EPR content of the composite material is higher than 18%. It can be seen that the weather resistance of the composite material is poor.

[0080] Comparing Comparative Examples 5 and 6 with Example 4, it can be seen that the weather resistance of the composite materials prepared by using talc powder with a particle size that is too small (1000 mesh) or too large (6000 mesh) is poor.

[0081] Comparing Comparative Examples 7 and 8 with Example 4, it can be seen that the flame retardant performance or weather resistance of the prepared composite materials is poor when the dosage of the brominated flame retardant is too low or too high.

[0082] In summary, the present invention starts from the key factors affecting the weather resistance of brominated flame-retardant polypropylene composite materials, through the optimization of polypropylene type and content, combined with the synergistic effect of talcum powder and carbon black in the composite material, under the conditions of specific homopolymer polypropylene content, copolymer polypropylene content, EPR content in copolymer polypropylene, EPR content in the prepared polypropylene composite material, talcum powder particle size, and brominated flame retardant content, only when each component is within the appropriate dosage range and the components can play a synergistic role, can a polypropylene composite material with excellent flame retardancy, weather resistance and mechanical properties be prepared. The prepared polypropylene composite material can be applied to parts such as automotive interiors that are exposed to direct sunlight for a long time.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A flame retardant and weather-resistant polypropylene composite material, characterized in that: The composition comprises the following components by weight: 1 to 32 parts of homopolymer polypropylene; 20 to 60 parts of copolymer polypropylene, 15 to 18 parts of brominated flame retardant, 5 to 6 parts of antimony trioxide, 15 to 25 parts of talc, 0.2 to 1 part of carbon black, and 0.1 to 1.5 parts of auxiliary agent; The particle size of the talcum powder is 3000-5000 mesh; The EPDM content in the polypropylene composite material is 12% to 18%; The content of ethylene-propylene rubber in the copolymerized polypropylene is 20% to 40%.

2. The flame retardant and weather resistant polypropylene composite material according to claim 1, characterized in that: The content of the copolymerized polypropylene is 32 to 60 parts.

3. The flame retardant and weather resistant polypropylene composite material according to claim 1, characterized in that: The content of ethylene-propylene rubber in the copolymerized polypropylene is 29% to 37.8%.

4. The flame retardant and weather resistant polypropylene composite material according to claim 1, characterized in that: The brominated flame retardant is at least one of decabromodiphenylethane, tetrabromobisphenol A, octabromoether and octabromotriphenylether.

5. The flame retardant and weather resistant polypropylene composite material according to claim 1, characterized in that: The auxiliary agent includes 0.1 to 0.3 parts of a primary antioxidant, 0.1 to 0.3 parts of an auxiliary antioxidant, and 0.2 to 0.5 parts of a light stabilizer.

6. The flame retardant and weather resistant polypropylene composite material according to claim 5, characterized in that: The main antioxidant is a hindered phenol antioxidant; the auxiliary antioxidant is a phosphite antioxidant; and the light stabilizer is a hindered amine light stabilizer.

7. A method for preparing the flame-retardant and weather-resistant polypropylene composite material according to any one of claims 1 to 6, characterized in that: The following steps are involved: The components are weighed respectively, mixed, melted, extruded, granulated, and cooled to obtain the product.

8. The preparation method according to claim 7, characterized in that: The mixing is performed at a rotation speed of 200 r / min to 500 r / min for 5 min to 8 min.

9. Use of the flame retardant and weather resistant polypropylene composite material according to any one of claims 1 to 6 in automobile parts.

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