A high-impact, low-shrinkage transparent PP and its preparation method and application

Abstract

This invention relates to plastic modification technology, specifically to a high-impact, low-shrinkage transparent polypropylene (PP), its preparation method, and its application in automobile bumpers. Polypropylene, a nucleating agent, a transparent inorganic filler, rubber, glass fiber, a compatibilizer, and additives are melt-mixed to produce the high-impact, low-shrinkage transparent PP. This invention primarily targets the requirements of automobile OEMs by modifying PP to achieve increased light transmittance, high toughness, high modulus, and low shrinkage. This material is primarily used in automobile bumpers, where LEDs can be placed inside, creating ambient lighting and creating stunning lighting.

Description

Technical Field

[0001] The invention belongs to plastic modification technology, and specifically relates to a high-impact, low-shrinkage transparent PP, a preparation method thereof, and application thereof in automobile bumpers. Background Art

[0002] Polypropylene (PP) is a widely used general-purpose plastic with excellent overall performance. Its automotive application has surged in recent years, primarily in large components such as bumpers, spoilers, and interior glass front fenders. Countries around the world have established safety and technical standards for automotive plastic bumpers, placing high demands on bumper materials. These materials not only require excellent high and low temperature impact resistance, paint adhesion, aging resistance, heat resistance, and cold resistance, but in the era of new energy vehicles, OEMs are also raising aesthetic standards. Most existing bumpers utilize a combination of PP, EPDM, and talc, achieving high impact and low shrinkage requirements but suffering from poor transparency (light transmittance below 15%). Addressing this imbalance in performance, including high transmittance, low shrinkage, high impact, and high modulus, presents a technical challenge. Summary of the Invention

[0003] The present invention mainly modifies PP to improve light transmittance, high toughness, high modulus and low shrinkage at the requirements of automobile main engine manufacturers. The material is mainly used in automobile bumpers. LEDs can be placed inside the bumpers, and ambient lights can be designed through LEDs to achieve dazzling lighting.

[0004] The present invention adopts the following technical solution: a method for preparing high-impact, low-shrinkage transparent PP, which comprises melt-mixing polypropylene, a nucleating agent, a transparent inorganic filler, rubber, glass fiber, a compatibilizer, and an additive to obtain high-impact, low-shrinkage transparent PP; wherein the additive is a conventional plastic additive, such as an antioxidant and a weathering agent.

[0005] In the present invention, the polypropylene is composed of copolymer polypropylene, homopolypropylene, and terpolymer polypropylene. Preferably, the mass ratio of the copolymer polypropylene, homopolypropylene, and terpolymer polypropylene is (22-30):(22-30):8. More preferably, the mass ratio of the copolymer polypropylene, homopolypropylene, and terpolymer polypropylene is (25-28):(25-28):8.

[0006] In the present invention, the copolymerized polypropylene is a PP / PE copolymer; the homopolymerized polypropylene is a PP homopolymer; and the terpolymerized polypropylene is a propylene ethylene butene copolymer.

[0007] In the present invention, the transparent inorganic filler is transparent talc powder with a particle size of 2000-3000 mesh; the diameter of the glass fiber is 1-50 μm, preferably 10-20 μm, and the length is 3-10 mm, preferably 4-6 mm.

[0008] In the present invention, the rubber is POE rubber; and the compatibilizer is maleic anhydride grafted polypropylene.

[0009] In the present invention, the mass ratio of polypropylene, nucleating agent, transparent inorganic filler, rubber, glass fiber, compatibilizer and additive is (50-70): (0.5-1.5): (5-15): (15-25): (3-8): (2-8): (0.5-1.5); preferably, the mass ratio of polypropylene, nucleating agent, transparent inorganic filler, rubber, glass fiber, compatibilizer and additive is (55-65): (0.8-1.2): (8-10): (15-20): (4-6): (5-8): (0.8-1.2).

[0010] In the present invention, polypropylene, a nucleating agent, a transparent inorganic filler, rubber, glass fiber, a compatibilizer and an additive are mixed, and then melt-mixed through an extruder to obtain high-impact, low-shrinkage transparent PP; the mixing and extrusion are specifically conventional technologies, and twin-screw extrusion can be used for melt plasticization. After extrusion, cooling, pelletizing, drying and other processes, high-impact, low-shrinkage transparent PP particles are obtained.

[0011] The invention discloses a method for preparing the high-impact, low-shrinkage transparent PP and a method for preparing the high-impact, low-shrinkage transparent PP.

[0012] The present invention further discloses the use of the high-impact, low-shrinkage transparent PP in the preparation of high-impact, low-shrinkage transparent plastic parts.

[0013] The invention discloses the application of the high-impact, low-shrinkage transparent PP in the preparation of automobile plastic parts.

[0014] The invention discloses the application of the high-impact, low-shrinkage transparent PP in the preparation of bumpers.

[0015] Most of the existing bumpers are made of PP+EPDM+talcum powder, which meet the requirements of high impact and low shrinkage, but have poor transparency (light transmittance below 15%). The present invention has a light transmittance of more than 40% and a notched impact strength of more than 25kj / m 2 , flexural modulus above 1600MPa, and shrinkage within 1.1%, which solves the problem of imbalance in performance of high light transmittance, low shrinkage, high impact and high modulus. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The light transmission effect of the particles after sample preparation in Example 1 is very good. DETAILED DESCRIPTION

[0017] To address the problem of low transparency of existing high-impact, low-shrinkage PP materials, the present invention mixes polypropylene, a nucleating agent, a transparent inorganic filler, rubber, glass fiber, a compatibilizer, and an additive, and then melt-mixes the mixture through an extruder to obtain high-impact, low-shrinkage, transparent PP. The mixing and extrusion are specifically conventional techniques, and twin-screw extrusion can be used for melt plasticization. After extrusion, cooling, pelletizing, drying, and other processes, high-impact, low-shrinkage, transparent PP particles are obtained.

[0018] In the present invention, the polypropylene is composed of copolymerized polypropylene, homopolymerized polypropylene, and terpolymerized polypropylene. Preferably, the mass ratio of copolymerized polypropylene, homopolymerized polypropylene, and terpolymerized polypropylene is (22-30):(22-30):8. More preferably, the mass ratio of copolymerized polypropylene, homopolymerized polypropylene, and terpolymerized polypropylene is (25-28):(25-28):8. The combination of the three PP polymers can improve light transmittance while maintaining low shrinkage.

[0019] In the present invention, the copolymerized polypropylene is a PP / PE copolymer; the homopolymerized polypropylene is a PP homopolymer; and the terpolymerized polypropylene is a propylene ethylene butene copolymer.

[0020] In the present invention, the transparent inorganic filler is transparent talc powder with a particle size of 2200-2800 mesh; the diameter of the glass fiber is 1-50 μm, preferably 10-20 μm, and the length is 3-10 mm, preferably 4-6 mm.

[0021] In the present invention, the rubber is POE rubber; and the compatibilizer is maleic anhydride grafted polypropylene.

[0022] The formula composition (mass percentage) for preparing high impact, low shrinkage transparent PP of the present invention is as follows:

[0023] Copolymer PP 25-30%

[0024] Homopolymer PP 25-30%

[0025] Ternary copolymer PP 5-10%

[0026] Nucleating agent 1%-3%

[0027] Transparent talc 5-10%

[0028] Long glass fiber 3-7%

[0029] Antioxidant 0.3-0.5%

[0030] Weathering agent 0.5-0.7%

[0031] PP-G compatibilizer 3-8%

[0032] P0E rubber allowance

[0033] The materials used in the present invention are added to a high-speed mixer by weight, mixed, and then fed directly into a twin-screw extruder for melt plasticization. After extrusion, cooling, pelletizing, and drying, a high-impact, low-shrinkage transparent PP is obtained. The extruder processing temperature is: 120-150°C for zones 1 to 5; 160-190°C for zones 6 to 10; and 200°C for zones 11 to 13. The screw speed is set at 320-350 rpm, with the main feed screw speed at 30-35 rpm.

[0034] The following experiments illustrate the technological advancements of the present invention. The specific raw materials are existing products that meet the conventional requirements for plastic modification. The specific preparation operations and performance testing are conventional techniques.

[0035] Copolymer PP: PP / PE copolymer, Formosa Chemical K8003;

[0036] Homopolymer PP: PP homopolymer material, Korea Petrochemical HJ4012;

[0037] Ternary copolymer PP: PP FS6612L;

[0038] PP nucleating agent: ADK STAB NA-21;

[0039] Transparent talc: Xufeng Powder TM-212, 2500 mesh;

[0040] POE rubber: Dow Chemical PL-1880G;

[0041] Long glass fiber: Jushi 988A, length 4.5mm;

[0042] PP-G compatibilizer: Energy Light 200A;

[0043] Ordinary talcum powder: Heshan Chemical Talc Powder 888;

[0044] EPDM rubber: Mitsui 3092;

[0045] Additives: commonly used antioxidant 1010 and anti-UV agent UV234, the mass ratio of the two is 4:6.

[0046] Processing method: The raw materials are added to a high-speed mixer and mixed for 7 minutes. After removal, they are directly fed into a twin-screw extruder for melt plasticization. After extrusion, cooling, pelletizing, and drying, PP particles are obtained. The extruder processing temperature is: 120-150°C for zones 1 to 5; 160-190°C for zones 6 to 10; and 200°C for zones 11 to 13. The screw speed is set at 330 rpm, and the main feed screw speed is 35 rpm.

[0047] The present invention is described in detail below in conjunction with the embodiments, each portion being 1 kg.

[0048] Comparative Example 1

[0049] 98 parts of copolymerized PP, 1 part of PP nucleating agent and 1 part of auxiliary agent were added into a high-speed mixer and mixed for 7 minutes; the uniformly mixed material was melt-plasticized, extruded, cooled and pelletized through a twin-screw extruder, and the obtained composite pellets were dried in a drying oven at a temperature of 90°C for 3 hours to prepare a PP composite material pellet.

[0050] Comparative Example 2

[0051] 25 parts of copolymer PP, 25 parts of homopolymer PP, 25 parts of EPDM rubber, 20 parts of ordinary talc 888, 3 parts of PP-G compatibilizer, 1 part of additive, and 1 part of PP nucleating agent are added into a high-speed mixer and mixed for 7 minutes; the uniformly mixed materials are melt-plasticized, extruded, cooled, and pelletized through a twin-screw extruder, and the obtained composite pellets are dried in a drying oven at a temperature of 90°C for 3 hours to prepare PP composite material pellets.

[0052] Comparative Example 3

[0053] 25 parts of copolymer PP, 35 parts of homopolymer PP, 1 part of PP nucleating agent, 20 parts of POE rubber, 15 parts of transparent talc, 3 parts of PP-G compatibilizer and 1 part of auxiliary agent are added into a high-speed mixer and mixed for 7 minutes; the uniformly mixed materials are melt-plasticized, extruded, cooled and pelletized through a twin-screw extruder, and the obtained composite pellets are dried in a drying oven at a temperature of 90°C for 3 hours to prepare PP composite material pellets.

[0054] Comparative Example 4

[0055] 25 parts of copolymer PP, 30 parts of homopolymer PP, 1 part of PP nucleating agent, 20 parts of POE rubber, 15 parts of transparent talc, 5 parts of glass fiber, 3 parts of PP-G compatibilizer and 1 part of auxiliary agent are added into a high-speed mixer and mixed for 7 minutes; the uniformly mixed materials are melt-plasticized, extruded, cooled and pelletized through a twin-screw extruder, and the obtained composite pellets are dried in a drying oven at a temperature of 90°C for 3 hours to prepare PP composite material pellets.

[0056] Comparative Example 5

[0057] 30 parts of copolymer PP, 25 parts of homopolymer PP, 1 part of PP nucleating agent, 20 parts of POE rubber, 10 parts of transparent talc, 5 parts of glass fiber, 8 parts of PP-G compatibilizer and 1 part of auxiliary agent are added into a high-speed mixer and mixed for 7 minutes; the uniformly mixed materials are melt-plasticized, extruded, cooled and pelletized through a twin-screw extruder, and the obtained composite pellets are dried in a drying oven at a temperature of 90°C for 3 hours to prepare PP composite material pellets.

[0058] Comparative Example 6

[0059] 30 parts of copolymer PP, 30 parts of homopolymer PP, 1 part of PP nucleating agent, 20 parts of POE rubber, 8 parts of transparent talc, 5 parts of glass fiber, 5 parts of PP-G compatibilizer and 1 part of auxiliary agent are added into a high-speed mixer and mixed for 7 minutes; the uniformly mixed materials are melt-plasticized, extruded, cooled and pelletized through a twin-screw extruder, and the obtained composite pellets are dried in a drying oven at a temperature of 90°C for 3 hours to prepare PP composite material pellets.

[0060] Example 1

[0061] 26 parts of copolymer PP, 26 parts of homopolymer PP, 8 parts of ternary copolymer PP, 1 part of PP nucleating agent, 20 parts of POE rubber, 8 parts of transparent talc, 5 parts of glass fiber, 5 parts of PP-G compatibilizer and 1 part of auxiliary agent are added into a high-speed mixer and mixed for 7 minutes; the uniformly mixed materials are melt-plasticized, extruded, cooled and pelletized through a twin-screw extruder, and the obtained composite pellets are dried in a drying oven at a temperature of 90°C for 3 hours to prepare PP composite material pellets.

[0062] Material testing methods:

[0063] Melt index: According to ISO 1133, 230℃, 5kg, MFR ≥ 14g / 10min;

[0064] Charpy impact: ISO 179-1eA, 23°C A-notch, pendulum energy 2.75J, requirement ≥25kj / m 2 ;

[0065] Bending strength: ISO 178, 2 mm / min, required to be ≥1600MPa;

[0066] Light transmittance: ISO 13468-2, requirement ≥40%;

[0067] Haze: ISO 14782, ≥90%;

[0068] Shrinkage: ISO 294-4-2007, required to be less than or equal to 1.1%.

[0069] The test results of the products of the above embodiments and comparative examples are shown in Table 1. The pure PP material of comparative example 1 has a too large shrinkage rate, which will cause the product size to be unstable. As can be seen from comparative example 2, the conventional PP+EPDM+TD solution cannot meet the requirements in terms of transmittance and haze. As can be seen from comparative examples 4 and 3, the addition of glass fiber increases the modulus and reduces the shrinkage rate. Compared with group 2, group 3 has better transmittance, haze and modulus.

[0070]

[0071] Comparative Example 2-1

[0072] 25 parts of copolymer PP, 25 parts of homopolymer PP, 25 parts of EPDM rubber, 20 parts of transparent talc, 3 parts of PP-G compatibilizer, 1 part of additive, and 1 part of PP nucleating agent were added into a high-speed mixer and mixed for 7 minutes; the uniformly mixed material was melt-plasticized, extruded, cooled, and pelletized through a twin-screw extruder, and the obtained composite pellets were dried in a drying oven at a temperature of 90°C for 3 hours to prepare PP composite material pellets with a transmittance of 21%.

[0073] Comparative Example 2-2

[0074] 25 parts of copolymer PP, 25 parts of homopolymer PP, 25 parts of EPDM rubber, 15 parts of transparent talc, 5 parts of glass fiber, 3 parts of PP-G compatibilizer, 1 part of additive, and 1 part of PP nucleating agent were added to a high-speed mixer and mixed for 7 minutes; the uniformly mixed material was melt-plasticized, extruded, cooled, and pelletized through a twin-screw extruder, and the obtained composite pellets were dried in a drying oven at a temperature of 90°C for 3 hours to prepare PP composite material pellets with a transmittance of 17%.

[0075] Comparative Example 7

[0076] 28 parts of copolymer PP, 28 parts of homopolymer PP, 10 parts of ternary copolymer PP, 1 part of PP nucleating agent, 20 parts of POE rubber, 7 parts of glass fiber, 5 parts of PP-G compatibilizer and 1 part of auxiliary agent are added into a high-speed mixer and mixed for 7 minutes; the uniformly mixed material is melt-plasticized, extruded, cooled and pelletized through a twin-screw extruder, and the obtained composite pellets are dried in a drying oven at a temperature of 90°C for 3 hours to prepare a PP composite material pellet; if talcum powder is omitted, the shrinkage rate and light transmittance are unqualified, and if the glass fiber is increased, the product appearance will have warping defects.

[0077] Comparative Example 8

[0078] Regardless of the formulation, if POE is omitted, the impact strength will be very poor, the bumper will not be able to resist impact and collision, and cannot be used.

[0079] Comparative Example 9

[0080] Replacing the transparent talc powder in Example 1 with fumed silica of comparable particle size had no effect on improving the modulus, and the flexural modulus was unqualified.

[0081] Comparative Example 10

[0082] 52 parts of copolymer PP, 8 parts of ternary copolymer PP, 1 part of PP nucleating agent, 20 parts of POE rubber, 8 parts of transparent talc, 5 parts of glass fiber, 5 parts of PP-G compatibilizer and 1 part of auxiliary agent are added into a high-speed mixer and mixed for 7 minutes; the uniformly mixed materials are melt-plasticized, extruded, cooled and pelletized through a twin-screw extruder, and the obtained composite pellets are dried in a drying oven at a temperature of 90°C for 3 hours to prepare PP composite material pellets.

[0083] 52 parts of homopolymer PP, 8 parts of ternary copolymer PP, 1 part of PP nucleating agent, 20 parts of POE rubber, 8 parts of transparent talc, 5 parts of glass fiber, 5 parts of PP-G compatibilizer and 1 part of auxiliary agent are added into a high-speed mixer and mixed for 7 minutes; the uniformly mixed materials are melt-plasticized, extruded, cooled and pelletized through a twin-screw extruder, and the obtained composite pellets are dried in a drying oven at a temperature of 90°C for 3 hours to prepare PP composite material pellets.

[0084] The transmittance and shrinkage of these two types of PP particles do not meet the requirements.

[0085] Example 2

[0086] 25 parts of copolymer PP, 25 parts of homopolymer PP, 10 parts of ternary copolymer PP, 1 part of PP nucleating agent, 20 parts of POE rubber, 8 parts of transparent talc, 5 parts of glass fiber, 5 parts of PP-G compatibilizer and 1 part of auxiliary agent are added into a high-speed mixer and mixed for 7 minutes; the uniformly mixed materials are melt-plasticized, extruded, cooled and pelletized through a twin-screw extruder, and the obtained composite pellets are dried in a drying oven at a temperature of 90°C for 3 hours to prepare PP composite material pellets.

[0087] Example 3

[0088] 26 parts of copolymer PP, 27 parts of homopolymer PP, 7 parts of ternary copolymer PP, 1 part of PP nucleating agent, 20 parts of POE rubber, 8 parts of transparent talc, 5 parts of glass fiber, 5 parts of PP-G compatibilizer and 1 part of auxiliary agent are added into a high-speed mixer and mixed for 7 minutes; the uniformly mixed materials are melt-plasticized, extruded, cooled and pelletized through a twin-screw extruder, and the obtained composite pellets are dried in a drying oven at a temperature of 90°C for 3 hours to prepare PP composite material pellets.

[0089] Example 4

[0090] 26 parts of copolymer PP, 26 parts of homopolymer PP, 8 parts of ternary copolymer PP, 1 part of PP nucleating agent, 18 parts of POE rubber, 9 parts of transparent talc powder, 5 parts of glass fiber, 6 parts of PP-G compatibilizer and 1 part of auxiliary agent are added into a high-speed mixer and mixed for 7 minutes; the uniformly mixed materials are melt-plasticized, extruded, cooled and pelletized through a twin-screw extruder, and the obtained composite pellets are dried in a drying oven at a temperature of 90°C for 3 hours to prepare PP composite material pellets.

[0091] Example 5

[0092] 25 parts of copolymer PP, 27 parts of homopolymer PP, 7 parts of ternary copolymer PP, 1 part of PP nucleating agent, 20 parts of POE rubber, 8 parts of transparent talc powder, 5 parts of glass fiber, 6 parts of PP-G compatibilizer and 1 part of auxiliary agent are added into a high-speed mixer and mixed for 7 minutes; the uniformly mixed materials are melt-plasticized, extruded, cooled and pelletized through a twin-screw extruder, and the obtained composite pellets are dried in a drying oven at a temperature of 90°C for 3 hours to prepare PP composite material pellets.

[0093] Example 6

[0094] 26 parts of copolymer PP, 26 parts of homopolymer PP, 8 parts of ternary copolymer PP, 1 part of PP nucleating agent, 21 parts of POE rubber, 6 parts of transparent talc powder, 5 parts of glass fiber, 6 parts of PP-G compatibilizer and 1 part of auxiliary agent are added into a high-speed mixer and mixed for 7 minutes; the uniformly mixed materials are melt-plasticized, extruded, cooled and pelletized through a twin-screw extruder, and the obtained composite pellets are dried in a drying oven at a temperature of 90°C for 3 hours to prepare PP composite material pellets.

[0095] In the existing technology, the best materials for automobile bumpers are the PP-EPDM-TD series, which meet the requirements of high impact and low shrinkage, but have poor transparency (light transmittance below 15%). As modified particles, the compatibility between the various components, including several types of PP, and between the resin and the filler, has a significant effect on light transmittance, mechanical properties, etc. As common sense, the filler properties, component compatibility, and dispersion characteristics, combined with the properties of each material, jointly affect the performance of the PP modified material. The light-transmitting, low-shrinkage PP in the embodiment of the present invention has a balanced performance of impact strength, light transmittance, low shrinkage, and high modulus, all meeting the requirements. The prepared bumper can be installed with LED lights.

Claims

1. A method for preparing high-impact, low-shrinkage transparent PP, characterized in that: Polypropylene, a nucleating agent, a transparent inorganic filler, rubber, glass fiber, a compatibilizer and an additive are melt-mixed to obtain a high-impact, low-shrinkage transparent PP; the rubber is POE rubber; the polypropylene is composed of copolymer polypropylene, homopolypropylene and terpolymer polypropylene; the mass ratio of the copolymer polypropylene, homopolypropylene and terpolymer polypropylene is (22-30): (22-30): 8; the copolymer polypropylene is a PP / PE copolymer; the homopolypropylene is a PP homopolymer; the terpolymer polypropylene is a propylene ethylene butene copolymer; the mass ratio of the polypropylene, the nucleating agent, the transparent inorganic filler, the rubber, the glass fiber, the compatibilizer and the additive is (50-70): (0.5-1.5): (5-15): (15-25): (3-8): (2-8): (0.5-1.5).

2. The method for preparing high-impact, low-shrinkage transparent PP according to claim 1, characterized in that: The transparent inorganic filler is transparent talc powder with a particle size of 2000-3000 meshes; the diameter of the glass fiber is 1-50 μm and the length is 3-10 mm.

3. The method for preparing high-impact, low-shrinkage transparent PP according to claim 1, characterized in that: The compatibilizer is maleic anhydride grafted polypropylene.

4. The method for preparing high-impact, low-shrinkage transparent PP according to claim 1, characterized in that: The mass ratio of polypropylene, nucleating agent, transparent inorganic filler, rubber, glass fiber, compatibilizer and additives is (55-65): (0.8-1.2): (8-10): (15-20): (4-6): (5-8): (0.8-1.2).

5. High-impact, low-shrinkage transparent PP prepared by the method for preparing high-impact, low-shrinkage transparent PP according to claim 1.

6. Use of the high-impact, low-shrinkage transparent PP according to claim 5 in the preparation of high-impact, low-shrinkage transparent plastic parts.

7. Use of the high-impact, low-shrinkage transparent PP according to claim 5 in the preparation of automotive plastic parts.

8. Use of the high-impact, low-shrinkage transparent PP according to claim 5 in the preparation of bumpers.

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