High-transparency high-toughness polypropylene and preparation method thereof

Abstract

The invention discloses a high-transparency and high-toughness polypropylene material and a preparation method thereof, and the high-transparency and high-toughness polypropylene material is prepared from the following raw materials in parts by weight: 80-94 parts of polypropylene, 5-30 parts of a toughening agent, 0.1-0.5 part of a light stabilizer, 0.1-1 part of an antioxidant and 0.1-0.5 part of a nucleating agent, the polypropylene is polypropylene random copolymer, and the melt index of the polypropylene random copolymer is 1-10g / 10min under the conditions that the melt index is 230 DEG C and the weight of the polypropylene random copolymer is 2.16 kg; and the flexibilizer is an ethylene-propenyl elastomer with the density of less than or equal to 0.87 g / cm < 3 >. According to the invention, the polypropylene random copolymer and the ethylene-propenyl flexibilizer capable of toughening and keeping transparency at the same time are preferably selected, so that the polypropylene material has the characteristics of high transparency and high toughness at the same time.

Description

Technical Field

[0001] The invention belongs to the technical field of polypropylene modification, and in particular relates to high-transparency and high-toughness polypropylene and a preparation method thereof. Background Art

[0002] Polypropylene has many advantages such as low density, easy processing, good mechanical properties, and high cost performance, and is widely used in daily necessities, automobiles, home appliances and other fields. However, while the market pays attention to the performance of polypropylene materials, it also places higher and higher requirements on the aesthetics of the materials. At present, in the application scenarios such as the water storage bucket of the sweeping robot, the basket cover of the shared electric vehicle, and the transparent baby seat, the material is not only required to maintain certain mechanical properties, but also to have good light transmission effect.

[0003] Among polypropylene materials, homopolymer polypropylene and random polypropylene generally have good light transmission effects. Among them, random polypropylene has better light transmission effect, but it has poor toughness and insufficient modulus. Therefore, it is very important to maintain good mechanical properties while ensuring the light transmission effect of the material.

[0004] Patent document CN111763379A discloses the use of high-transmittance and high-rigidity polypropylene as the matrix, high aspect ratio, low-diameter one-dimensional fillers to replace traditional talcum powder fillers, and styrene elastomers with a small refractive index difference from PP as toughening agents to prepare high-transmittance and lightweight polypropylene composite materials. However, the material prepared by this method has poor low-temperature toughness, and the -30℃ cantilever beam notched impact can only reach 2.0 to 2.5 KJ / m 2 Around, the parts are prone to cracking when facing low-temperature impact. Patent document CN112795092A discloses the addition of organic α-crystal nucleating agents to form smaller microcrystalline areas and the use of nano-inorganic fillers, which ensure that the material has sufficient strength and dimensional stability while minimizing the obstruction of light by inorganic fillers, and is used to prepare polypropylene composite materials for highly light-transmitting automobile bumpers. However, the disadvantage of this method is that nano-inorganic fillers are relatively expensive, and simple melt blending is extremely prone to agglomeration during the extrusion process, so it is difficult to achieve industrial production in practice. The above two documents have greatly weakened the transparency of polypropylene materials due to the addition of fillers. If they are to be used in application scenarios with higher requirements for transparency (for example, a 2mm transmittance greater than 60%), the existing technology cannot meet the corresponding requirements.

[0005] Patent document CN112538215A discloses an impact-resistant, low-temperature-resistant, highly transparent polypropylene composition, which comprises, by weight: 100 parts of random copolymer polypropylene, 0.001-0.2 parts of primary antioxidant, 0.001-0.2 parts of auxiliary antioxidant, 0.001-0.2 parts of nucleating agent, 0.001-0.2 parts of acid absorbent, 3-20 parts of polypropylene-ethylene / propylene block copolymer, and 3-40 parts of vinyl elastomer. However, the melting index range of random copolymer polypropylene in the document is too large and the specific melting index is not given in the embodiment, so it is impossible to judge which kind of random copolymer polypropylene with melting index is specifically used, and its low-temperature impact strength cannot meet customer requirements; and its polypropylene-ethylene propylene block copolymer is a block structure composed of isotactic polypropylene segments and ethylene / propylene random copolymer segments, and the vinyl elastomer is a vinyl elastomer formed by copolymerization of ethylene and α-olefin, and their introduction will cause the transparency of the material to be seriously reduced. Summary of the invention

[0006] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a highly transparent and highly tough polypropylene material and a preparation method thereof, which has both high transparency and good toughness and is suitable for large-scale industrial production.

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

[0008] The high-transparency and high-toughness polypropylene material of the present invention is characterized in that it is prepared from the following raw materials in parts by weight, with the total parts being 100 parts: polypropylene: 80-94 parts, toughening agent: 5-30 parts, light stabilizer: 0.1-0.5 parts, antioxidant: 0.1-1 parts, nucleating agent: 0.1-0.5 parts;

[0009] The polypropylene is a random copolymer polypropylene, with a melt index of 230°C and a melt index of 1 to 10 g / 10 min under 2.16 kg. The material with a melt index lower than 1 g / 10 min is not easy to form, and the material with a melt index higher than 10 g / 10 min has poor toughness.

[0010] The toughening agent has a density of ≤0.87 g / cm 3 Ethylene propylene based elastomer; the elastomer has good compatibility with polypropylene materials, good toughening effect, small difference in refractive index with polypropylene, and its addition has little effect on the light transmittance of polypropylene materials; the density is higher than 0.87g / cm 3 There will be poor toughening effect and poor transparency;

[0011] The light stabilizer is a hindered amine light stabilizer;

[0012] The antioxidant is one of antioxidant 1010 (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate), antioxidant 168 (tris(2,4-di-tert-butylphenyl) phosphite), antioxidant 3114 (1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl) isocyanuric acid), DLTP (dilauryl thiodipropionate), or a mixture of several thereof;

[0013] The nucleating agent is an aryl phosphate salt nucleating agent, such as aryl phosphate sodium salt and aryl phosphate hydroxyaluminum salt.

[0014] The invention discloses a method for preparing a highly transparent and high-toughness polypropylene material, comprising the following steps: stirring and mixing the raw materials uniformly, and then feeding the raw materials into a barrel of a twin-screw extruder, and obtaining a modified polypropylene material through melting, blending, extruding, cooling, and granulating; the twin-screw extruder has a screw diameter of 35 mm, an aspect ratio of 40, a screw temperature of 120-210° C., a die head temperature of 200° C., and a main engine speed of 300-500 rpm.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] The present invention selects random copolymerized polypropylene and ethylene propylene-based toughening agents that can simultaneously toughen and maintain transparency, so that the polypropylene material has the characteristics of high transparency and high toughness. The raw materials of the present invention are easily available, the processing technology is simple, and it is convenient for industrial production. DETAILED DESCRIPTION

[0017] The present invention is further described below by means of specific implementation modes, and the embodiments are only used to illustrate the present invention but not to limit the present invention.

[0018] The raw materials used in this embodiment are all commercially available products.

[0019] Random copolymer polypropylene PP 5012, Formosa Plastics, 2mm sample transmittance 86%, melt index 1.5g / 10min (230℃, 2.16kg);

[0020] Random copolymer polypropylene PP 5070, Formosa Plastics, 2mm sample transmittance 85%, melt index 7.5g / 10min (230℃, 2.16kg);

[0021] Random copolymer polypropylene PP 5250T, Formosa Plastics, 2mm sample transmittance 82%, melt index 22g / 10min (230℃, 2.16kg);

[0022] Impact-resistant copolymer polypropylene PP EP548R, Zhenhai Petrochemical, 2mm sample transmittance 51%, melt index 30g / 10min (230℃, 2.16kg);

[0023] Homopolymer polypropylene PP Z30S, Zhenhai Petrochemical, 2mm sample transmittance 70%, melt index 28g / 10min (230℃, 2.16kg);

[0024] Toughener 1: Ethylene propylene copolymer, density 0.861g / cm 3 ,ExxonMobil Vistamaxx 6202;

[0025] Toughener 2: Ethylene propylene copolymer, density 0.879g / cm 3 , ExxonMobil Vistamaxx 3980FL;

[0026] Toughener 3: Ethylene butene copolymer, density 0.862g / cm 3 ,LG POE LC168;

[0027] Toughener 4: Ethylene octene copolymer, density 0.863 g / cm 3 , Dow POE 8150;

[0028] Nucleating agent: NA11 (sodium 2'2-methylenebis(4,6-di-tert-butylphenyl)phosphate), Japan Aidico.

[0029] Examples 1 to 5 and Comparative Examples 1 to 5

[0030] The raw material compositions of the high-transparency and high-toughness polypropylene of Examples 1 to 5 and Comparative Examples 1 to 5 are shown in Table 1, and the preparation method thereof comprises the following steps: stirring and mixing the raw materials evenly, and then feeding them into the barrel of a twin-screw extruder, and obtaining the modified polypropylene material through melting, blending, extrusion, cooling, and granulation; wherein the screw diameter of the twin-screw extruder is 35 mm, the aspect ratio is 40, the temperature from the feed port to the die is 120° C., 180° C., 210° C., 210° C., 210° C., 210° C., 200° C., 200° C., 200° C., and the main engine speed is 400 rpm.

[0031] Table 1 Formulas of Examples 1 to 6 and Comparative Examples 1 to 4, parts by weight

[0032]

[0033] The light transmittance and impact resistance of the polypropylene material injection molding samples prepared in Examples 1 to 5 and Comparative Examples 1 to 5 were tested. The results are shown in Table 2.

[0034] (1) Light transmittance performance: The test was conducted in accordance with GB / T 2410-2008 standard: light source A was used, and method A haze meter method was selected to test the light transmittance of the injection molded square plate (size 50 mm*50 mm*2.0 mm) of each sample.

[0035] (2) Izod notched impact strength and -20°C Izod notched impact strength: tested in accordance with ISO180-2019, type A notch.

[0036] Table 2 Test results of Examples 1 to 5 and Comparative Examples 1 to 5

[0037]

[0038] The light transmittance of the polypropylene material of the present invention in Examples 1-5 is greater than 60%, which has a relatively high light transmittance. However, the melt index of the random polypropylene in Example 3 is relatively high, resulting in a significant reduction in its impact strength, indicating that the toughness of the polypropylene material is better when the melt index of the random polypropylene is within 1 to 10 g / 10 min (230°C / 2.16 kg). From the comparison between Example 1 and Comparative Example 5, it can be seen that when the density of the ethylene propylene-based toughening agent is high, the impact strength of the polypropylene material will be greatly reduced. Therefore, the lower the density of the ethylene propylene-based toughening agent, the better its toughening effect. Therefore, the preferred density is ≤0.87 g / cm 3 Ethylene propylene-based elastomer. From the comparison between Example 1 and Comparative Examples 1-2, it can be seen that random copolymerized polypropylene has a higher light transmittance while maintaining good toughness, and the light transmittance is greater than 70%. By comparing Example 1 with Comparative Example 4, it is found that ethylene propylene has a higher transparency while maintaining good toughness.

Claims

1. A highly transparent and high-toughness polypropylene material, characterized in that: The invention is prepared from the following raw materials in parts by weight, the total parts being 100 parts: polypropylene: 80-94 parts, toughening agent: 5-30 parts, light stabilizer: 0.1-0.5 parts, antioxidant: 0.1-1 parts, nucleating agent: 0.1-0.5 parts; The polypropylene is a random copolymer polypropylene, with a melt index of 230°C and a melt index of 1 to 10 g / 10 min under 2.16 kg; the toughening agent has a density of ≤0.87 g / cm 3 Ethylene propylene based elastomer.

2. The highly transparent and high-toughness polypropylene material according to claim 1, characterized in that: The light stabilizer is a hindered amine light stabilizer.

3. The highly transparent and high-toughness polypropylene material according to claim 1, characterized in that: The antioxidant is one of antioxidant 1010, antioxidant 168, antioxidant 3114 and antioxidant DLTP, or a mixture of several of them.

4. The highly transparent and high-toughness polypropylene material according to claim 1, characterized in that: The nucleating agent is an aromatic phosphate nucleating agent.

5. The method for preparing the high-transparency and high-toughness polypropylene material according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: stirring and mixing the raw materials uniformly, and then feeding the raw materials into the barrel of a twin-screw extruder, and obtaining the modified polypropylene material through melting, blending, extruding, cooling and granulating; the twin-screw extruder has a screw diameter of 35 mm, an aspect ratio of 40, a screw temperature of 120-210° C., a die head temperature of 200° C., and a main engine speed of 300-500 rpm.

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