A polypropylene composition, its preparation method and application

Abstract

The present invention discloses a polypropylene composition, a preparation method thereof and an application. The polypropylene composition of the present invention comprises the following components by weight: 40-80 parts of copolymerized polypropylene; 5-20 parts of low-flowability elastomer; 10-30 parts of linear low-density polyethylene, wherein the EPR Mw / PP Mw ratio of the copolymerized polypropylene is ≥2.0, and the low-flowability elastomer is an ethylene-α-olefin copolymer, and the melt mass flow rate at a test standard of ISO1133-1-2011, a test condition of 190°C and 2.16 Kg is 0.3-5 g / 10 min. The copolymerized polypropylene is adopted in the polypropylene composition of the present invention, and the scattering and diffusing effects on light are more obvious. Further, the microphase separation of the blend system composed of the low-flowability elastomer and the linear low-density polyethylene increases sharply, and the average dispersed size of the EPR phase increases by more than twice, making the scattering and diffusing effects of the entire polymer blend on light more obvious, and significantly reducing the gloss of the polypropylene composition.

Description

Technical Field

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

[0002] Polypropylene compositions have been widely used in the automotive industry due to their advantages such as light weight, solvent resistance, easy processing and recycling. However, in recent years, the strong plastic feel brought by high-gloss interior parts in the field of automotive interiors has become an important factor affecting the consumer experience. Low-gloss automotive interior parts have a matte and elegant visual effect, and can reduce visual interference to drivers and passengers, which is beneficial to driving safety and improves driving comfort. Therefore, in order to meet consumers' increasing quality requirements for automotive interior materials, it is of great significance to develop polypropylene composite materials that meet the requirements of low-gloss automotive interior parts.

[0003] In recent years, some scientific and technological workers have done some work on how to reduce the gloss of polypropylene composite materials, such as obtaining low-gloss materials by adding various matting agents. Prior art CN101759919A discloses a low-gloss polypropylene composite material and a preparation method thereof, wherein the low-gloss polypropylene composite material is prepared according to the following weight % raw materials: polypropylene 58-86%; wollastonite 13-30%; other inorganic fillers 0-12%; toughening agent POE 0-15%; antioxidant 0.1-2%; other additives 0-5%. The above-mentioned low-gloss polypropylene composite material reduces the surface gloss of the composite material by adding wollastonite, but the effect of reducing the gloss of automotive interior leather parts is relatively limited, and it also affects the notched impact strength of the material, and cannot meet the ultra-low gloss performance requirements of automotive leather type interior parts of some automobile OEMs. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the defects and shortcomings of the existing polypropylene composition, that is, the high glossiness and inability to meet the ultra-low gloss performance requirements of automotive leather-grain type interior parts, and to provide a polypropylene composition, which can not only achieve low glossiness but also will not affect other properties of the polypropylene composite material.

[0005] Another object of the present invention is to provide a method for preparing the polypropylene composition.

[0006] Another object of the present invention is to provide a use of a polypropylene composition in the preparation of automotive leather-grain type interior trim parts.

[0007] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0008] A polypropylene composition, comprising the following components in parts by weight:

[0009] 40 - 80 parts of copolymerized polypropylene;

[0010] 5 - 20 parts of low - flow elastomer;

[0011] 10 - 30 parts of linear low - density polyethylene,

[0012] wherein the EPR Mw / PP Mw ratio of the copolymerized polypropylene ≥ 2.0,

[0013] The low - flow elastomer is an ethylene - α - olefin copolymer, and its melt mass - flow rate at a test standard of ISO1133 - 1 - 2011, test conditions of 190 °C and 2.16 Kg is 0.3 - 5 g / 10 min.

[0014] Among them, it should be noted that:

[0015] The EPR Mw / PP Mw ratio of the copolymerized polypropylene of the present invention is determined according to the standard of GB / T24282—2021 "Determination of the Content of Xylene - Soluble Matter in Plastics - Polypropylene"; the EPR Mw / PP Mw ratio of the copolymerized polypropylene is the ratio of the weight - average molecular weight of the EPR phase to the weight - average molecular weight of the PP phase in the copolymerized polypropylene.

[0016] The copolymerized polypropylene of the present invention has a relatively large molecular weight of the EPR phase, a large ratio of the weight - average molecular weight of the EPR phase to the weight - average molecular weight of the PP phase, that is, a large viscosity difference between the EPR phase and the PP phase. The large viscosity difference between the EPR phase and the PP phase leads to a larger micro - phase separation inside the matrix resin, a larger EPR dispersion size, which is conducive to forming a phase - state distribution structure of micro - phase separation, and has a more obvious refraction, scattering and diffusion effect on light. Therefore, the gloss of the polypropylene compound is lower.

[0017] Furthermore, there is a large viscosity difference between the low - flow elastomer and the copolymerized polypropylene, and the micro - phase separation between the two phases is more obvious. Therefore, the gloss of the polypropylene composition can be reduced. Compared with the existing technical solutions for reducing gloss by adding a matting agent, the solution of the present invention will not cause an obvious decrease in the notched impact strength, and has a better effect of reducing gloss.

[0018] Preferably, by weight, it includes the following components:

[0019] 50 - 70 parts of copolymerized polypropylene;

[0020] 10 - 15 parts of low - flow elastomer;

[0021] 15 - 25 parts of linear low - density polyethylene.

[0022] Preferably, the EPR Mw / PP Mw ratio of the copolymerized polypropylene is 3 - 5.

[0023] Preferably, the low-flowability elastomer has a melt mass flow rate of 1 to 3 g / 10 min under the test standard ISO1133-1-2011, test conditions of 190 °C and 2.16 Kg.

[0024] The difference in the two-phase glass transition temperatures Tg(PP phase) - Tg(EPR phase) between the PP phase in the copolymerized polypropylene and the EPR phase in the linear low-density polyethylene is ≥ 51 °C.

[0025] It should be noted that:

[0026] The test method for the glass transition temperature uses the DSC method. DSC characterizes the glass transition temperature of a material by measuring the change in the specific heat capacity of the material with temperature. There will be a large change in the specific heat capacity before and after the glass transition temperature Tg. The glass transition temperature can be determined according to the curve. The glass transition temperature is usually a step in the endothermic direction. The glass transition is a region. This method usually takes the intersection of the line equidistant from the two extrapolated baseline lines and the curve as the glass transition temperature. The test temperature range is -60 °C to 100 °C, and the heating and cooling rate is 20 °C / min. First, heat from 23 °C to 100 °C, then cool from 100 °C to -60 °C, and then heat from -60 °C to 100 °C.

[0027] In the polypropylene composition, the glass transition temperature (Tg) of the EPR phase of the linear low-density polyethylene is relatively low. The difference in the two-phase glass transition temperatures (Tg) between the PP phase in the copolymerized polypropylene resin and the EPR phase in the linear low-density polyethylene is ≥ 51 °C. The significant difference in the Tg values of the two phases in the composition significantly expands the microphase separation of the polypropylene composition through the linear low-density polyethylene. Together with the low-flowability elastomer, the microphase separation of the blend system increases sharply. In particular, the dispersed size of the EPR phase becomes significantly larger, and the average dispersed size of the EPR phase increases by more than twice, making the scattering and diffusing effects of the entire polymer blend on light more obvious.

[0028] More preferably, the difference in the two-phase glass transition temperatures Tg(PP phase) - Tg(EPR phase) between the PP phase in the copolymerized polypropylene and the EPR phase in the linear low-density polyethylene is 52 to 53 °C.

[0029] In the specific implementation, in order to meet the usage requirements of most scenarios and obtain good processing fluidity of the polypropylene material, the copolymerized polypropylene has a melt mass flow rate of 30 to 100 g / 10 min under the test standard ISO1133-1-2011, test conditions of 230 °C and 2.16 Kg.

[0030] In a specific embodiment, the melt mass flow rate of the linear low density polyethylene of the present invention may be 10-25 g / 10 min, and the test standard is ISO 1133-1-2011, 190 °C, 2.16 Kg load.

[0031] In a specific embodiment, the low-flow elastomeric ethylene-α-olefin copolymer of the present invention may be one or more of ethylene-hexene copolymer, ethylene-butene copolymer, and ethylene-octene copolymer.

[0032] In a specific embodiment, in order to meet the application and processing requirements of the polypropylene composition, 0.05-5 parts by weight of a processing aid may be further added to the polypropylene composition of the present invention, and the processing aid is selected from one or a mixture of several of pigments, antioxidants, weathering agents, and lubricants.

[0033] Among them, the pigment of the present invention may be a conventional pigment in the art, such as an organic or inorganic pigment.

[0034] The inorganic pigment may be titanium white, chrome yellow, cadmium yellow, molybdenum chrome red, iron red (yellow), cadmium red, ultramarine blue, cobalt blue, iron blue, chrome green, cobalt green, metal powder, mica pearlescent, carbon black, etc.

[0035] The organic pigment may be azo-based, thiazine-based, phthalocyanine-based, dye-based, etc.

[0036] The antioxidant of the present invention may be a conventional antioxidant in the art, such as a hindered phenol antioxidant, a phosphite antioxidant, etc.

[0037] The weathering agent of the present invention may be a conventional antioxidant in the art, such as a hindered amine weathering agent.

[0038] The lubricant of the present invention may be a conventional lubricant in the art: such as calcium stearate and zinc stearate, etc.

[0039] In practical applications, a filler may also be added to the polypropylene composition of the present invention, and its dosage is a conventional dosage in the art. For example, by weight, it is 1-40 parts. The inorganic filler may adopt conventional inorganic fillers in the art, such as one or a mixture of several of talc powder, calcium carbonate, wollastonite, and whiskers.

[0040] The present invention also specifically protects a method for preparing a polypropylene composition, including the following steps:

[0041] Mix the copolymerized polypropylene, low-flow elastomer, and linear low density polyethylene, and then add them to an extruder, and perform melt mixing at a temperature of 170 °C - 240 °C, and then pelletize, cool, and dry to obtain the polypropylene composition.

[0042] Among them, it should be noted that:

[0043] The mixing of the components of the polypropylene composition of the present invention can be carried out by conventional mixing methods in the art.

[0044] The extrusion granulation of the present invention can also be carried out by conventional extrusion granulation methods in the art. For example, the extruder can be a twin-screw extruder or a reciprocating single-screw extruder, and the length-diameter ratio of the screw is not less than 32.

[0045] The present invention also specifically protects the application of a polypropylene composition in the preparation of automotive leather-grain type interior parts.

[0046] The polypropylene composition of the present invention significantly reduces the gloss of polypropylene products, meets the requirements of automotive interior parts for low gloss, and can meet the requirements of automotive leather-grain type interior parts of major vehicle manufacturers, such as Volkswagen K3A leather-grain interior parts, Ford YUKON leather-grain interior parts, and Geely JA124 leather-grain interior parts, etc.

[0047] Compared with the prior art, the beneficial effects of the present invention are:

[0048] In the polypropylene composition of the present invention, the copolymerized polypropylene is a copolymerized polypropylene. The large viscosity difference between the EPR phase and the PP phase results in a larger microphase separation inside the matrix resin, a larger EPR dispersion size, and a more obvious scattering and diffusing effect on light, which can effectively reduce the gloss of the polypropylene composition. Further, the microphase separation of the blend system composed of a low-flow elastomer and linear low-density polyethylene increases sharply in a synergistic manner, and the average dispersion size of the EPR phase increases by more than twice, making the scattering and diffusing effects of the entire polymer blend on light more obvious, and further reducing the gloss of the polypropylene composition.

[0049] The gloss of the polypropylene composition of the present invention can be reduced to 1.4 or less, and it has no effect on the mechanical properties of the polypropylene composition. The Izod notched impact strength can reach 20 KJ / m 2 above, which can fully meet the ultra-low gloss performance requirements of automotive leather-grain type interior parts and is widely used in the preparation of automotive leather-grain type interior parts. Detailed Embodiments

[0050] The following further illustrates the present invention in conjunction with specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the raw material reagents used in the embodiments of the present invention are conventional raw material reagents purchased.

[0051] Copolymerized polypropylene:

[0052] Copolymerized polypropylene-1: PP EP5091, EPR Mw / PP Mw is 3.17, melt mass flow rate is 30 g / 10 min (test standard ISO 1133-1-2011, 2.16 kg, 230 °C), BASELL.

[0053] Random copolymer polypropylene - 2: PP EP548R, EPR Mw / PP Mw is 2.00, melt mass - flow rate is 30 g / 10 min (test standard ISO 1133 - 1 - 2011, 2.16 kg, 230 °C), CNOOC and Shell Petrochemical Company Limited.

[0054] Random copolymer polypropylene - 3: PP BI997, EPR Mw / PP Mw is 5.00, melt mass - flow rate is 100 g / 10 min (test standard ISO 1133 - 1 - 2011, 2.16 kg, 230 °C), Hanwha Total Petrochemical.

[0055] Random copolymer polypropylene - 4: PP 7905E1, EPR Mw / PP Mw is 5.96, melt mass - flow rate is 100 g / 10 min (test standard ISO 1133 - 1 - 2011, 2.16 kg, 230 °C), ExxonMobil.

[0056] Random copolymer polypropylene - 5: Random copolymer polypropylene PP M2600R, EPR Mw / PP Mw is 0.80, melt mass - flow rate is 30 g / 10 min (2.16 kg, 230 °C), Shanghai Petrochemical Company.

[0057] Linear low - density polyethylene (LLDPE): LLDPE M2320, melt mass - flow rate is 25 g / 10 min, test standard ISO 1133 - 1 - 2011, test conditions 190 °C, 2.16 Kg, manufacturer: Maoming Petrochemical;

[0058] Low - flow elastomer:

[0059] Elastomer A: Ethylene - butene copolymer, melt mass - flow rate is 0.3 g / 10 min (2.16 kg, 190 °C), POE 7387, DOW;

[0060] Elastomer B: Ethylene - butene copolymer, melt mass - flow rate is 1.0 g / 10 min (2.16 kg, 190 °C), POE 7467, DOW;

[0061] Elastomer C: Ethylene - butene copolymer, melt mass - flow rate is 5.0 g / 10 min (2.16 kg, 190 °C), POE 7447, DOW;

[0062] Elastomer D: Ethylene - butene copolymer, melt mass - flow rate is 3.0 g / 10 min (2.16 kg, 190 °C), POE 8450, DOW;

[0063] Elastomer E: Ethylene-butene copolymer, melt mass flow rate of 13.0 g / 10 min (2.16 kg, 190 °C), POE 8137, DOW;

[0064] Elastomer F: Ethylene-butene copolymer, melt mass flow rate of 0.2 g / 10 min (2.16 kg, 190 °C), POE 7487, DOW;

[0065] Talcum powder: TYT-777A, Tianyuan.

[0066] Test method or standard:

[0067] Glossiness: ASTM D523-2014, light incident angle of 60°, the test instrument is a 3nh glossiness tester.

[0068] Izod notched impact strength: ISO 180-2000, Type A notch, impact tester, specimen size: 5 80 mm × 10 mm × 4 mm, notch width 0.2 mm, pendulum energy 2.75 J, impact speed 3.5 m / s.

[0069] Examples 1 to 12

[0070] A polypropylene composition, calculated by weight parts, includes the components shown in Table 1 below:

[0071] Table 1

[0072]

[0073] The preparation method of the polypropylene compositions in Examples 1 to 13 above is specifically as follows: 10 According to the weight parts of each component in Table 1, the copolymerized polypropylene, linear low density polyethylene, elastomer, and talcum powder are mixed in a high-speed mixer, and then added to a twin-screw extruder with a length-diameter ratio of 40:1, and melt mixing is carried out at a temperature of 220 °C, and then pelletized, cooled, and dried to obtain the polypropylene composition.

[0074] The Geely JA124 automotive interior leather pattern parts are prepared by injection molding under the conditions of an injection temperature of 200 °C, an injection pressure of 45 MPa, an injection speed of 45 s, a holding pressure of 30 MPa, and a holding time of 5 s. The surface glossiness of the test piece is tested according to ASTM D523; the ISO mechanical spline is injection molded according to the above injection process conditions, and the Izod notched impact strength is tested according to the ISO 180-2000 standard.

[0075] At an injection temperature of 200 °C, an injection pressure of 45 MPa, an injection speed of 45 s, a holding pressure of 30 MPa,

[0076] and a holding time of 5 s, the Geely JA124 automotive interior leather pattern parts are prepared by injection molding. The surface glossiness of the test piece is tested according to ASTM D523; the ISO mechanical spline is injection molded according to the above injection process conditions, and the Izod notched impact strength is tested according to the ISO 180-2000 standard.

[0077] The Izod notched impact strength is tested according to the ISO 180-2000 standard.

[0078] Comparative Examples 1 to 7

[0079] A polypropylene composition, calculated by weight parts, comprises the components shown in Table 2 below:

[0080] Table 2

[0081]

[0082] The preparation methods of the polypropylene compositions of the above Comparative Examples 1-7 are specifically referred to as follows:

[0083] Mix the copolymerized polypropylene, linear low density polyethylene, and elastomer in a high-speed mixer according to the weight parts of each component in Table 2, and then add them to a twin-screw extruder with a length-diameter ratio of 40:1, and conduct melt mixing at a temperature of 220°C, and then pelletize, cool, and dry to obtain the polypropylene composition.

[0084] Under the conditions of an injection molding temperature of 200°C, an injection pressure of 45 MPa, an injection speed of 45 s, a holding pressure of 30 MPa, and a holding time of 5 s, prepare the interior trim leather pattern parts of Geely JA124 by injection molding, and test the surface glossiness of the sample parts according to ASTM D523-2014; inject ISO mechanical splines according to the above injection molding process conditions, and test the notched izod impact performance according to the ISO 180-2000 standard.

[0085] Result Detection

[0086] Measure the relevant glossiness of the interior trim leather pattern parts of Geely JA124 prepared in the above Examples and Comparative Examples, and measure the notched izod impact strength of the mechanical splines prepared in the above Examples and Comparative Examples according to the ISO 180 standard. The specific test results are shown in Table 3 and Table 4 below.

[0087] Table 3. Test Results

[0088]

[0089]

[0090] Among them, in the polypropylene composition, the difference in the glass transition temperature of the two phases of the PP phase in the copolymerized polypropylene resin and the EPR phase in the linear low density polyethylene is also related to the contents of the copolymerized polypropylene resin and the linear low density polyethylene in the composition. Even if the component morphologies of the two are the same, their contents are different, and the glass transition temperature difference is also different.

[0091] As can be seen from Table 1, the interior trim leather pattern parts of Geely JA124 prepared from the polypropylene composition of the present invention according to the standard have a lower leather pattern glossiness, and the measured value of the leather pattern glossiness at 60° can reach 1.4 or less, and the notched izod impact strength is 20 KJ / m 2The above can fully meet the performance requirements of automotive leather-grained interior parts. Among them, Examples 3-5 and Example 7 are preferred copolypropylene raw materials and formulations, and the measured glossiness at 60° of their leather grains can be further reduced to reach 0.7-1.0, and the notched Izod impact strength can reach 30-41 KJ / m 2 The above. Examples 3-5 and Example 11 are preferred low-flow elastomer raw materials and formulations, and the measured glossiness at 60° of their leather grains can be further reduced to reach 0.7-0.9, and the notched Izod impact strength can reach 30-42 KJ / m 2 The above.

[0092] Among them, Comparative Examples 1 and 2 are cases where the dosage of the elastomer is too high or too low. Not only is the measured glossiness at 60° of their leather grains above 1.4, but the notched Izod impact strength of the polypropylene composition also cannot reach 20 KJ / m 2 The above.

[0093] Comparative Examples 3 and 4 are cases where the dosage of linear low-density polyethylene is too high or too low. Not only is the measured glossiness at 60° of their leather grains 2.0-2.8, above 1.4, but the notched Izod impact strength of the polypropylene composition also cannot meet the requirements.

[0094] Comparative Example 5 uses a non-copolypropylene raw material, and the EPR Mw / PP Mw ratio of the copolypropylene is less than 2, being 0.80. The measured glossiness at 60° of the leather grains is as high as 2.4, and it cannot meet the requirement of a low glossiness value.

[0095] Comparative Examples 6 and 7 are cases where the melt mass flow rate of the flowable elastomer is not within the protection scope of the present invention, being 0.2 g / 10 min and 13 g / 10 min respectively. Whether the melt mass flow rate is too high or too low, it cannot meet the requirement of low glossiness.

[0096] And it can further reduce the glossiness of the leather-grained parts, meeting the requirements of automotive interior parts for glossiness.

[0097] Obviously, the above embodiments of the present invention are merely examples for clearly explaining the present invention, rather than limiting the implementation manners of the present invention. For those of ordinary skill 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 implementation manners here. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims

1. A polypropylene composition, characterized in that, By weight, it comprises the following components: 40 - 80 parts of copolymerized polypropylene; 5 - 20 parts of low - flow elastomer; 10 - 30 parts of linear low - density polyethylene, wherein the EPR Mw / PP Mw ratio of the copolymerized polypropylene is 2.0 - 5.96, the low - flow elastomer is an ethylene - α - olefin copolymer, and its melt mass flow rate at the test standard ISO1133 - 1 - 2011, test conditions of 190 °C and 2.16 Kg is 0.3 - 5 g / 10 min.

2. The polypropylene composition according to claim 1, characterized in that, By weight, it comprises the following components: 50 - 70 parts of copolymerized polypropylene; 10 - 15 parts of low - flow elastomer; 15 - 25 parts of linear low - density polyethylene.

3. The polypropylene composition according to claim 1, characterized in that, The EPR Mw / PP Mw ratio of the copolymerized polypropylene is 3 - 5.

4. The polypropylene composition according to claim 1, wherein The melt mass flow rate of the low - flow elastomer at the test standard ISO1133 - 1 - 2011, test conditions of 190 °C and 2.16 Kg is 1 - 3 g / 10 min.

5. The polypropylene composition according to claim 1, characterized in that, The melt mass flow rate of the copolymerized polypropylene at the test standard ISO1133 - 1 - 2011, test conditions of 230 °C and 2.16 Kg is 30 - 100 g / 10 min.

6. The polypropylene composition according to claim 1, wherein The low - flow elastomer is one or more of ethylene - hexene copolymer, ethylene - butene copolymer and ethylene - octene copolymer.

7. A method for preparing the polypropylene composition according to any one of claims 1-6, characterized in that, It comprises the following steps: Mix the copolymerized polypropylene, low - flow elastomer and linear low - density polyethylene, then add them into an extruder, carry out melt mixing at a temperature of 170 °C - 240 °C, and then pelletize, cool and dry to obtain the polypropylene composition.

8. Use of the polypropylene composition according to any one of claims 1 - 6 in the preparation of automotive grained interior parts.

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