Polypropylene material and use thereof

Abstract

A polypropylene material and a use thereof; a light stabiliser containing (CH2)n structural units is added to copolymerised polypropylene resin, wherein n is an integer greater than or equal to 5, to effectively improve the weather resistance of the material, so that after xenon lamp accelerated ageing, the colour difference value is low, the gloss retention rate is high, and there is no whitening, being suitable for preparing automotive interior and exterior leather textured parts such as door panels, instrument panels, wheel arch trims, bumper trims, and exterior decorative door panels.

Description

A polypropylene material and its application Technical Field

[0001] The invention belongs to the technical field of polymer materials, and particularly relates to a polypropylene material and application thereof. Background Art

[0002] Polypropylene, due to its excellent processing and physical properties, is widely used in the automotive industry, particularly in automotive interior and exterior trim materials. Common automotive interior and exterior materials such as door panels, instrument panels, fender flares, and bumper trims are designed with a leather-grain finish. Compared to plain panels, this fine grain structure reduces gloss by increasing surface roughness, effectively reducing the perceived cheap plastic feel of the finished part and enhancing the overall vehicle's comfort and refinement.

[0003] These leather-grained exterior parts are typically exposed to direct sunlight, which leads to a certain degree of aging over time, manifesting as defects such as discoloration, precipitation, and cracking. Currently, parts suppliers and automakers primarily use color difference after xenon lamp accelerated aging to assess part resistance. However, gloss retention and additive precipitation can also affect the material's freshness after long-term use. However, research in this area is limited.

[0004] Summary of the Invention

[0005] In view of the shortcomings of the prior art, the present invention aims to provide a polypropylene material and its application. The polypropylene material has excellent weather resistance, exhibits low color difference, high gloss retention, and no whitening after xenon lamp accelerated aging (referring to SAEJ 2527-2004 standard), and can maintain its novelty even after long-term use. The material can be used to prepare automotive interior and exterior leather-grain parts.

[0006] In order to achieve the above object, the present invention provides a polypropylene material comprising the following components in parts by weight:

[0007] Here, n is an integer ≥5.

[0008] Carbon black absorbs ultraviolet light, protecting the polymer chains in the copolymerized polypropylene resin from direct radiation exposure, thereby improving weather resistance. The aforementioned light stabilizers, due to their long alkyl chains, are highly compatible with the copolymerized polypropylene resin. This not only provides better protection for the copolymerized polypropylene resin, but also reduces or prevents additive precipitation, which can cause whitening and blooming of the material.

[0009] Copolymer polypropylene resins, due to the presence of a certain amount of rubber phase (i.e., vinyl segments) in their molecular chains, offer good compatibility with light stabilizers containing longer alkyl segments and can also reduce the overall gloss of the material, thereby maintaining a high gloss retention rate after xenon lamp accelerated aging. Homopolymer polypropylene resins, on the other hand, do not contain vinyl segments and, due to their high crystallinity and overall high gloss, are not conducive to maintaining the material's gloss retention rate after xenon lamp accelerated aging.

[0010] The polypropylene material exhibits excellent weather resistance due to the combined effects of the various components at specific concentrations. After xenon lamp accelerated aging (referring to SAEJ 2527-2004 standard), the color difference value ΔE is less than 0.85, the gloss retention rate is greater than 88%, and there is little or no blushing. Even after long-term use, the material can maintain its novelty and is suitable for the preparation of automotive interior and exterior leather-grained parts, such as door panels, instrument panels, wheel arches, bumper trims, and exterior door panels.

[0011] The containing (CH2) n (CH2) in the structural unit of the light stabilizer n The structural unit is continuous (CH2) n Structural unit.

[0012] n is an integer ≥ 5, such as 5, 7, 9 or 12. In some embodiments, n is 6 to 8, so that the polypropylene material has better weather resistance, lower color difference ΔE after xenon lamp accelerated aging (referring to SAEJ 2527 standard), and higher gloss retention.

[0013] In some embodiments, the (CH2) n The light stabilizer of the structural unit includes at least one of hindered amines and benzophenones.

[0014] When the carbon black particle size D50 is too small, it tends to agglomerate, resulting in uneven distribution and relatively weak weather resistance of the polypropylene material. When the carbon black particle size D50 is too large, its hiding power decreases, resulting in relatively weak weather resistance of the polypropylene material. To improve the weather resistance of the polypropylene material, in some embodiments, the carbon black particle size D50 is 14 to 81 nm, such as 15 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, or 80 nm. In a specific embodiment, the carbon black particle size D50 is 19.5 to 51 nm, such as 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, or 50 nm, further improving the weather resistance of the resulting polypropylene material. The carbon black particle size D50 is measured using a laser particle size analyzer according to the test standard GB / T 19077-2016.

[0015] The rubber phase content in the copolymerized polypropylene resin not only affects the weather resistance of the resulting polypropylene material, but also affects the appearance of the resulting polypropylene material; the melt flow rate of the copolymerized polypropylene resin also affects the weather resistance of the resulting polypropylene material. In some embodiments, the rubber phase content in the copolymerized polypropylene resin is 18 wt% to 50 wt% (e.g., 19 wt%, 20 wt%, 30 wt%, 40 wt%, or 50 wt%, etc.), and the melt flow rate is above 8 g / 10 min (e.g., 8 g / 10 min, 10 g / 10 min, 15 g / 10 min, 20 g / 10 min, 25 g / 10 min, 30 g / 10 min, 35 g / 10 min, or 40 g / 10 min, etc.) at 230° C. and a load of 2.16 kg. By controlling the rubber phase content and melt flow rate in the copolymerized polypropylene resin within the above ranges, the weather resistance of the polypropylene material is improved and the probability of whitening is reduced. In particular, in a specific embodiment, the rubber phase content in the copolymerized polypropylene resin is 25wt% to 41wt% (such as 25wt%, 27wt%, 30wt%, 32wt%, 35wt%, 37wt% or 40wt%, etc.), and the melt flow rate of the copolymerized polypropylene resin is above 15g / 10min (optionally 15 to 32g / 10min, such as 15g / 10min, 17g / 10min, 20g / 10min, 25g / 10min, 30g / 10min or 32g / 10min, etc.) at 230°C and a load of 2.16kg. The obtained polypropylene material has better weather resistance and no whitening phenomenon. The rubber phase content in the copolymerized polypropylene resin is characterized by placing 1 g of the polymer sample in 100 mL of 98% by mass n-decane and extracting at 145°C to fully dissolve the rubber phase. After cooling to room temperature, the crystallized polypropylene component is filtered. 500 mL of acetone is added to the filtrate to precipitate the dissolved rubber phase. The filtrate is filtered, dried, and weighed for calculation. The melt flow rate of the copolymerized polypropylene resin is measured according to GB / T 3682.2-2018, "Thermoplastics - Determination of Melt Mass Flow Rate and Melt Volume Flow Rate." The same applies to the following.

[0016] In some embodiments, the lubricant includes at least one of polysiloxane and polyethylene wax.

[0017] In some embodiments, the Fe2O3 content of the talc is less than 0.25wt%, such as 0.24wt%, 0.20wt%, 0.16wt%, 0.12wt%, 0.08wt%, 0.05wt%, 0.03wt%, 0.01wt% or 0. The Fe2O3 in the talc is an impurity that can induce degradation of polypropylene, reducing its weather resistance and heat aging resistance. Therefore, the Fe2O3 content of the talc is preferably less than 0.25wt% so that the polypropylene material obtains better weather resistance and heat aging resistance. When the Fe2O3 content of the talc is less than 0.21wt%, especially when the Fe2O3 content of the talc is 0-0.15wt%, the weather resistance and heat aging resistance of the resulting polypropylene material are further improved. The Fe2O3 content in the talc can be measured by elemental analysis, the same below.

[0018] In some embodiments, the mass fraction of the copolymerized polypropylene resin in the polypropylene material is greater than 65%, such as 67%, 70%, 80%, 90%, 92%, etc.

[0019] The carbon black in the polypropylene material can be added in pure form or mixed with other toners. In some embodiments, the carbon black in the polypropylene material is mixed with other toners, and the weight of the carbon black accounts for more than 75% of the total weight of the toner, such as 75%, 80%, 90%, 95%, 99%, etc.

[0020] In some embodiments, the antioxidant includes a primary antioxidant and a secondary antioxidant, and the weight ratio of the primary antioxidant to the secondary antioxidant is 3:2 to 2:3, wherein the primary antioxidant includes at least one of hindered phenols, amines, etc., and the secondary antioxidant includes at least one of phosphites, thioesters, etc.

[0021] In some embodiments, the preparation method of the polypropylene material comprises the following steps: mixing the raw materials, feeding the raw materials into a screw extruder for melt extrusion, granulating and drying to obtain the polypropylene material. The screw extruder can be a twin-screw extruder, etc.; the aspect ratio of the screw extruder can be 30:1-40:1; and the melt extrusion conditions can be as follows: zone 1 temperature of 100-120°C, zone 2 temperature of 190-210°C, zone 3 temperature of 210-230°C, zone 4 temperature of 210-230°C, zone 5 temperature of 210-230°C, zone 6 temperature of 210-230°C, zone 7 temperature of 210-230°C, zone 8 temperature of 210-230°C, zone 9 temperature of 210-230°C, and the main engine speed of 250-600 rpm.

[0022] The present application also provides the use of the polypropylene material in automotive interior and exterior leather parts, such as door panels, instrument panels, exterior decorative panels, etc.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] (1) This application is made by adding (CH2) n Light stabilizer with structural unit (n≥5) to effectively improve the weather resistance of polypropylene materials;

[0025] (2) The polypropylene material of the present application has good weather resistance under the combined effect of the specific contents of the various components. After xenon lamp accelerated aging (refer to SAEJ 2527 standard), the color difference value ΔE is less than 0.85, the gloss retention rate is greater than 88%, and there is no whitening. Even after long-term use, the material can maintain its novelty and is suitable for use as an automotive interior and exterior decoration material, such as for preparing automotive interior and exterior leather parts, such as door panels, instrument panels, wheel eyebrows, bumper trim panels, door exterior decorative panels, etc. DETAILED DESCRIPTION

[0026] 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 all fall within the protection scope of the present invention. The experimental reagents and instruments involved in the implementation of the present invention are all conventional common reagents and instruments unless otherwise specified.

[0027] Examples and Comparative Examples

[0028] Each embodiment and comparative example provides a polypropylene material. The compositions of these polypropylene materials are shown in Tables 1 and 2. The preparation method comprises the following steps: uniformly mixing the raw materials of each component, feeding them into the main feed port of a twin-screw extruder for melt extrusion, granulating and drying to obtain the corresponding polypropylene composite;

[0029] The melt extrusion conditions of the twin-screw extruder are as follows: zone 1 temperature 120°C, zone 2 temperature 190°C, zone 3 temperature 210°C, zone 4 temperature 210°C, zone 5 temperature 210°C, zone 6 temperature 230°C, zone 7 temperature 230°C, zone 8 temperature 230°C, zone 9 temperature 230°C, main engine speed 350 rpm;

[0030] The length-to-diameter ratio of the twin-screw extruder is 40:1.

[0031] The components used in the above examples and comparative examples are as follows:

[0032] Copolymer polypropylene resin 1: rubber phase content 40wt%, melt flow rate 30g / 10min, Lihe Zhixin KA30;

[0033] Copolymer polypropylene resin 2: rubber phase content 28wt%, melt flow rate 16g / 10min, Formosa Chemical K9017;

[0034] Copolymer polypropylene resin 3: rubber phase content 27wt%, melt flow rate 28g / 10min, Yanshan Petrochemical K9829H;

[0035] Copolymer polypropylene resin 4: rubber phase content 19wt%, melt flow rate 30g / 10min, China Petrochemical EP548RQ;

[0036] Copolymer polypropylene resin 5: rubber phase content 49wt%, melt flow rate 24g / 10min, Lihe Zhixin KA40;

[0037] Copolymer polypropylene resin 6: rubber phase content of 27 wt%, melt flow rate of 10 g / 10 min, CNOOC Shell EP300M;

[0038] Homopolymer polypropylene resin: melt flow rate is 25g / 10min, China Petrochemical PPH-Y26;

[0039] Talc powder 1:3000 mesh, Fe2O3 content 0.07%, Xinda SD-9286;

[0040] Talc 2: 3000 mesh, Fe2O3 content 0.14%, Tianyuan TYT-777A;

[0041] Talc 3: 3000 mesh, Fe2O3 content 0.20%, Xinda SD-9488;

[0042] Talc 4: 3000 mesh, Fe2O3 content 0.24%, Xinda SD-9679;

[0043] Carbon black 1: pure carbon black, particle size D50 is 20nm, Anhui Heiyu 1013F;

[0044] Carbon black 2: pure carbon black, particle size D50 25 nm, Columbia PFEB;

[0045] Carbon black 3: pure carbon black, particle size D50 is 50 nm, Cabot N550;

[0046] Carbon black 4: pure carbon black, particle size D50 of 15 nm, Cabot 600L;

[0047] Carbon black 5: pure carbon black, particle size D50 is 80nm, Cabot N762;

[0048] Carbon Black 6: Contains carbon black, iron oxide red, and titanium dioxide, wherein the mass fraction of carbon black is 75%, and the particle size D50 is 25 nm. The carbon black brand is Columbia PFEB, and the iron oxide red and titanium dioxide are commercially available.

[0049] Light stabilizer 1: hindered amine, containing (CH2) n Structural unit, n=6, Rianlon light stabilizer 944;

[0050] Light stabilizer 2: Benzophenone, containing (CH2) n Structural unit, n = 7, Lionon UV-531;

[0051] Light stabilizer 3: hindered amine, containing (CH2) n Structural unit, n=8, light stabilizer 770;

[0052] Light stabilizer 4: benzotriazole, containing (CH2) n Structural unit, n=1, Rianlon light stabilizer 325;

[0053] Light stabilizer 5: benzotriazole, does not contain (CH2) n Structural unit, i.e. n = 0, Rianlon light stabilizer 327;

[0054] Lubricant 1: Zhejiang Jiahua HG-600S, polysiloxane;

[0055] Lubricant 2: Honeywell 540A, polyethylene wax;

[0056] Antioxidant: A mixture of hindered phenols and phosphites, with a mass ratio of 1:1.

[0057] The melt flow rates of the copolymerized polypropylene resin and the homopolymerized polypropylene resin are measured according to the standard GB / T 3682.2-2018 “Thermoplastics - Determination of Melt Mass Flow Rate and Melt Volume Flow Rate”, under the test conditions of 230° C. and a load of 2.16 kg.

[0058] Unless otherwise specified, the components and raw materials used in the examples and comparative examples of the present application are all commercially available raw materials, and the components and raw materials used in each parallel experiment are all of the same kind.

[0059] The polypropylene materials from each example and comparative example were injection molded into standard 3mm thick leather grain panels of the same specifications. These panels were then subjected to xenon lamp aging tests, and the color, gloss, and appearance of the leather grain surface before and after aging were evaluated. Xenon lamp aging was conducted according to SAEJ 2527-2004 conditions for 2100 hours. Color was measured using a CM-2500C spectrophotometer. Gloss was measured according to GB 8807-1988 at a 60° angle. The back (bright side) of the leather grain panels was observed under a magnifying glass (10x magnification), and the appearance was rated as follows:

[0060] Level 1: Good surface, no appearance defects such as whitening,

[0061] Level 2: The surface is slightly whitened.

[0062] Level 3: Severe precipitation, noticeable whitening, and frosting.

[0063] Color difference ΔE = color value E (before aging) - color value E (after aging), gloss retention rate (%) = gloss (after aging) / gloss (before aging) × 100. The test results are shown in Table 3.

[0064] Table 1

[0065] Table 2

[0066] Table 3

[0067] As shown in Table 3, the polypropylene materials obtained in the examples of the present application have good weather resistance. After xenon lamp accelerated aging (referring to SAEJ 2527-2004 standard), the color difference value ΔE is less than 0.85, the gloss retention rate is greater than 88%, and there is no whitening. Therefore, the polypropylene materials are suitable for preparing automotive interior and exterior leather parts, such as door panels, instrument panels, wheel arches, bumper trims, and door exterior decorative panels.

[0068] Comparison of Examples 2, 4-5 with Comparative Examples 1-2 shows that compared with the control examples 1-2, the control examples 2, 4-5 do not contain (CH2) n Light stabilizers containing structural units or (CH2) n Light stabilizer with structural unit but n<5, adding (CH2) n Light stabilizers with structural units of n≥5 can make the material more weather-resistant.

[0069] In Comparative Example 3, the amount of light stabilizer used was too little, resulting in poor improvement in the weather resistance of the material; in Comparative Example 4, the amount of light stabilizer used was too much, resulting in easy precipitation, whitening, and blooming.

[0070] In Comparative Example 5, the material has poor weather resistance due to the low amount of carbon black used and poor covering ability; in Comparative Example 6, the material has poor weather resistance due to the high amount of carbon black used, which is difficult to disperse evenly and has defects in local distribution.

[0071] From the comparison of Examples 2, 6 to 9, it can be seen that the particle size D50 of carbon black affects the weather resistance of the material. When the particle size D50 of carbon black is in the range of 19.5 to 51, the weather resistance of the obtained material is better; when the particle size D50 of carbon black is relatively low, such as 15 nm, agglomeration is very likely to occur due to the small particle size, resulting in uneven local distribution of carbon black, resulting in relatively poor weather resistance of the material; when the particle size D50 of carbon black is relatively high, such as 80 nm, the covering ability is reduced due to its excessively large particle size, resulting in poor weather resistance of the material.

[0072] Comparison of Examples 2, 11, and 15 shows that the rubber phase content of the copolymerized polypropylene resin affects the material's weatherability. When this content is within the range of 25 wt% to 41 wt%, the resulting material exhibits better weatherability. However, when this content is lower, such as 25 wt%, the low polyethylene segment content leads to relatively poor compatibility with the light stabilizer, resulting in relatively poor weatherability. When this content is higher, such as 49 wt%, the excessively high rubber phase content easily causes phase separation, resulting in uneven distribution of the additive between the rubber and crystalline phases, and poor appearance and weatherability. Furthermore, the melt flow rate (MFR) of the copolymerized polypropylene resin also affects the material's weatherability. When the MFR is low, such as 10 g / 10 min, the poor fluidity leads to uneven distribution of the light stabilizer throughout the molded part, also resulting in poor weatherability. Therefore, a MFR of 15 to 32 g / 10 min is preferred.

[0073] From the comparison of Examples 2 and 16 to 18, it can be seen that the Fe2O3 content in talc powder affects the weather resistance of the material. When the Fe2O3 content in talc powder is high, such as 0.24wt%, Fe2O3 induces more obvious degradation of polypropylene, resulting in poor weather resistance and heat aging resistance of the material. Therefore, it is preferred that the Fe2O3 content in talc powder is less than 0.21wt%.

[0074] 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 material, characterized in that: The composition comprises the following components in parts by weight: Here, n is an integer ≥5.

2. The polypropylene material according to claim 1, characterized in that The n is an integer in the range of 6 to 8.

3. The polypropylene material according to claim 1, characterized in that The containing (CH2) n The light stabilizer of the structural unit includes at least one of hindered amines and benzophenones.

4. The polypropylene material according to claim 1, characterized in that The particle size D50 of the carbon black is 14 to 81 nm, preferably 19.5 to 51 nm.

5. The polypropylene material according to claim 1, characterized in that The rubber phase content in the copolymerized polypropylene resin is 18wt% to 50wt%, and the melt flow rate is above 8g / 10min at 230°C and a load of 2.16kg; preferably, the rubber phase content in the copolymerized polypropylene resin is 25wt% to 41wt%, and the melt flow rate is 15 to 32g / 10min at 230°C and a load of 2.16kg.

6. The polypropylene material according to claim 1, characterized in that The lubricant includes at least one of polysiloxane and polyethylene wax.

7. The polypropylene material according to claim 1, characterized in that The Fe2O3 content of the talc is less than 0.25wt%.

8. The polypropylene material according to claim 7, characterized in that The Fe2O3 content of the talc powder is 0-0.15wt%.

9. The polypropylene material according to claim 1, characterized in that At least one of the following conditions is met: (1) The melt flow rate of the copolymerized polypropylene resin is 15 to 32 g / 10 min at 230° C. and a load of 2.16 kg; (2) The antioxidant includes a primary antioxidant and a secondary antioxidant, the weight ratio of the primary antioxidant to the secondary antioxidant is 3:2 to 2:3, wherein the primary antioxidant includes at least one of hindered phenols and amines, and the secondary antioxidant includes at least one of phosphites and thioesters.

10. Use of the polypropylene material according to any one of claims 1 to 9 in the preparation of automotive interior and exterior leather grain parts.

Images