High-melt-index low-temperature-resistant impact-resistant transparent polypropylene special material and preparation method thereof

Abstract

The invention discloses a high-melt-index low-temperature-resistant impact-resistant transparent polypropylene special material and a preparation method thereof. The polypropylene special material comprises the following components in parts by weight: 60-94 parts of polypropylene random copolymer, 0-31 parts of polypropylene block copolymer, 0-25 parts of an elastomer modifier, 1-2 parts of a PP flowable agent and 5-9 parts of a PP anti-reflection agent. The special polypropylene material provided by the invention has good elongation at break, simply supported beam notch impact strength at low temperature, bending strength, bending modulus and transparency.

Description

Technical Field

[0001] The present invention belongs to the technical field of polypropylene resin materials, and particularly relates to a special high melt index low temperature impact resistant transparent polypropylene material and a preparation method thereof. Background Art

[0002] Polypropylene material is a product obtained by polymerizing propylene monomer under the action of a certain catalytic system with hydrogen or ethylene, mixing the obtained polypropylene powder with additives, and melting, kneading and granulating through an extruder. It has the characteristics of light weight, good chemical stability, non-toxic, harmless and easy to process and form. At present, it has been widely used in the fields of national economy and people's livelihood such as food packaging, medical devices, construction, and automotive parts, bringing great convenience to modern life.

[0003] Although polypropylene products are widely used in various industries, domestic high-end polypropylene products mainly rely on imports. The root cause is that domestic polypropylene materials have significant shortcomings such as being prone to oxidation when exposed to the outdoor for a long time, insufficient high-temperature rigidity and poor low-temperature toughness. Therefore, how to optimize polypropylene processing into modified polypropylene through physical modification or chemical modification to improve its mechanical properties is an urgent problem to be solved at present. Random copolymer polypropylene (PP-R) is a polypropylene material obtained by randomly copolymerizing propylene and a small amount of comonomers (such as ethylene, butene, and hexene, etc.) under the action of a certain catalytic system. With its relatively balanced mechanical properties and good comprehensive properties, it has become a research hotspot of general polyolefin materials in recent years. Its structural characteristics are different from those of homopolymer or block copolymer polypropylene, making the PP-R pipe more heat-resistant than polyethylene (PE) pipe, more ductile than homopolymer polypropylene (PP-H) pipe, and having a longer service life than block copolymer polypropylene (PP-B) pipe. Therefore, PP-R has become a new type of polypropylene material and has been widely used in the preparation of household pipes, with the advantages of corrosion resistance, low cost, simple and convenient installation, etc. However, when the random copolymer polypropylene (PP-R) material is in a low-temperature environment, its toughness drops sharply, and even typical brittle fracture occurs, that is, the PP-R pipe is prone to pipeline bursting under cold climate conditions, greatly limiting its application scenarios and geographical scope. When the temperature drops to room temperature, it still has moderate impact strength, while when the temperature drops to -4 °C or lower, it is difficult to maintain strong toughness.

[0004] In the prior art, most of the toughening modifications of PP-R are achieved by introducing elastomers, inorganic rigid particles or nano-fillers as toughening agents, or by regulating the crystallization of polypropylene. For example, Wuhan Jinniu Economic Development Co., Ltd. discloses a high impact-resistant PP-R pipe and its preparation method in CN112175293A. The strength and toughness of the pipe are mainly improved by introducing polyolefin elastomers and nucleating agents, combining physical blending modification and chemical copolymerization modification. The polyolefin elastomer is an ethylene-propylene elastomer, and the nucleating agent masterbatch is granulated from an organic metal salt nucleating agent. However, the processing temperature of this method is as high as 190-210 °C, and annealing treatment for 2-5 h is required, resulting in high production energy consumption. However, the aforementioned toughening technical solutions basically only solve the problem of toughening at room temperature and cannot solve the problem of toughening at low temperature. Summary of the Invention

[0005] In order to overcome the deficiencies of the above prior art, the present invention provides a special high melt index low temperature impact-resistant transparent polypropylene material and its preparation method. The polypropylene special material of the present invention has good elongation at break, notched izod impact strength at low temperature, flexural strength, flexural modulus and transparency.

[0006] The purpose of the present invention is to provide a special high melt index low temperature impact-resistant transparent polypropylene material, and the polypropylene special material comprises the following components: 60-94 parts by weight of random copolymer polypropylene, 0-31 parts by weight of block copolymer polypropylene, 0-25 parts by weight of elastomer modifier, 1-2 parts by weight of PP flow agent, and 5-9 parts by weight of PP clarifier.

[0007] In some embodiments of the present invention, the polypropylene special material comprises the following components: 60-94 parts by weight of random copolymer polypropylene, 5-31 parts by weight of block copolymer polypropylene, 5-25 parts by weight of elastomer modifier, 1-2 parts by weight of PP flow agent, and 5-9 parts by weight of PP clarifier.

[0008] In some embodiments of the present invention, the melt index of the random copolymer polypropylene under the conditions of 230 °C / 2.16 kg is 55-65 g / 10 min, the tensile yield stress is 35.1 MPa, the flexural modulus is 1680 MPa, and the notched izod impact strength at 23 °C is 1.4 kJ / m 2 .

[0009] In some embodiments of the present invention, the melt index of the random copolymer polypropylene under the conditions of 230 °C / 2.16 kg is 58.8 g / 10 min, the tensile yield stress is 35.1 MPa, the flexural modulus is 1680 MPa, and the notched izod impact strength at 23 °C is 1.4 kJ / m 2 .

[0010] In some embodiments of the present invention, the block copolymerized polypropylene has a melt index of 1.0 to 2.0 g / 10 min at 230 °C / 2.16 kg, a tensile yield stress ≥ 22.0 MPa, a flexural modulus ≥ 900 MPa, and a notched Izod impact strength ≥ 10 kJ / m at 23 °C 2 .

[0011] In some embodiments of the present invention, the block copolymerized polypropylene has a melt index of 1.54 g / 10 min at 230 °C / 2.16 kg, a tensile yield stress of 25.5 MPa, a flexural modulus of 1040 MPa, and a notched Izod impact strength of 45 kJ / m at 23 °C 2 .

[0012] In some embodiments of the present invention, the PP flow agent is composed of 97 - 99 wt% polypropylene and 1 - 3 wt% di-tert-butyl peroxide, with a density of 0.89 - 0.96 g / cm 3 , and has a melt index of greater than 2000 g / 10 min at 230 °C / 2.16 kg and a Vicat softening point of 152 °C

[0013] In some embodiments of the present invention, the PP flow agent is composed of 97 - 99 wt% polypropylene and 1 - 3 wt% di-tert-butyl peroxide, with a density of 0.93 g / cm 3 , and has a melt index of greater than 2000 g / 10 min at 230 °C / 2.16 kg and a Vicat softening point of 152 °C

[0014] In some embodiments of the present invention, the melting point of the PP clarifying agent is 180 - 230 °C

[0015] In some embodiments of the present invention, the elastomeric modifier includes but is not limited to styrene-butadiene rubber

[0016] Another object of the present invention is to provide a method for preparing a high melt index low temperature resistant impact resistant transparent polypropylene special material, comprising the following steps:

[0017] Mix the random copolymerized polypropylene, block copolymerized polypropylene, PP flow agent, elastomeric modifier, and PP clarifying agent, stir, melt, knead, extrude, and pelletize to obtain the high melt index low temperature resistant impact resistant transparent polypropylene special material

[0018] In some embodiments of the present invention, the stirring time is 30 - 60 minutes and the stirring temperature is 25 ± 1 °C

[0019] Another object of the present invention is to provide an application of the high melt index low temperature resistant impact resistant transparent polypropylene special material in food packaging

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) By adding PP-B and PP-R for melt blending as a common matrix, the present invention can significantly improve the elongation at break and the notched Izod impact strength at low temperature of the special polypropylene material.

[0022] (2) By adding a PP flow agent and a PP clarifying agent, the present invention can improve the flexural strength, flexural modulus and notched Izod impact strength at low temperature of the special polypropylene material.

[0023] (3) By adding an elastomer modifier, the present invention can greatly improve the elongation at break and the notched Izod impact strength at low temperature of the special polypropylene material. Detailed implementation manners

[0024] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0025] The random copolymer polypropylene used in all the following examples and comparative examples has the trade name of Sinopec Maoming PPR-M55s, and the manufacturer is Dongguan Hongyi Plastic Raw Materials Co., Ltd.; the block copolymer polypropylene used has the trade name of Sinopec Maoming PPB-M02d, and the manufacturer is Dongguan Hongyi Plastic Raw Materials Co., Ltd.; the elastomer modifier used is thermoplastic styrene-butadiene rubber (CAS: 9003-55-8); the PP flow agent used is composed of 97-99 wt% polypropylene (CAS: 9003-07-0) and 1-3 wt% di-tert-butyl peroxide (CAS: 110-05-4), and the manufacturer is Dongguan Dinghai Plastic Chemical Co., Ltd.; the manufacturer of the PP clarifying agent used is Dongguan Xingyuan Chemical Co., Ltd., and its model is XY-6115AM.

[0026] Example 1

[0027] This example provides a special high melt index low temperature resistant impact transparent polypropylene material, and the steps of its preparation method are as follows:

[0028] Take 1.88 kg of random copolymer polypropylene, 0.02 kg of PP flow agent, and 0.1 kg of PP clarifying agent, mix them evenly and put them into a high-speed mixer, and stir well at 25 ± 1 °C for 30 minutes. After the stirring is completed, melt, knead, extrude and pelletize through a twin-screw extruder to obtain a special high melt index low temperature resistant impact transparent polypropylene material.

[0029] Example 2

[0030] This example provides a special material for high melt index, low temperature resistant and impact resistant transparent polypropylene. The steps of its preparation method are as follows:

[0031] Take 1.84 kg of random copolymer polypropylene, 0.02 kg of PP flow agent, and 0.14 kg of PP transparency enhancer. After mixing evenly, put them into a high-speed mixer and stir well at 25 ± 1 °C for 45 minutes. After the stirring is completed, carry out melting, mixing, extrusion, and pelletizing through a twin-screw extruder to obtain the special material for high melt index, low temperature resistant and impact resistant transparent polypropylene.

[0032] Example 3

[0033] This example provides a special material for high melt index, low temperature resistant and impact resistant transparent polypropylene. The steps of its preparation method are as follows:

[0034] Take 1.8 kg of random copolymer polypropylene, 0.02 kg of PP flow agent, and 0.18 kg of PP transparency enhancer. After mixing evenly, put them into a high-speed mixer and stir well at 25 ± 1 °C for 40 minutes. After the stirring is completed, carry out melting, mixing, extrusion, and pelletizing through a twin-screw extruder to obtain the special material for high melt index, low temperature resistant and impact resistant transparent polypropylene.

[0035] Example 4

[0036] This example provides a special material for high melt index, low temperature resistant and impact resistant transparent polypropylene. The steps of its preparation method are as follows:

[0037] Take 1.26 kg of random copolymer polypropylene, 0.62 kg of block copolymer polypropylene, 0.02 kg of PP flow agent, and 0.1 kg of PP transparency enhancer. After mixing evenly, put them into a high-speed mixer and stir well at 25 ± 1 °C for 60 minutes. After the stirring is completed, carry out melting, mixing, extrusion, and pelletizing through a twin-screw extruder to obtain the special material for high melt index, low temperature resistant and impact resistant transparent polypropylene.

[0038] Example 5

[0039] This example provides a special material for high melt index, low temperature resistant and impact resistant transparent polypropylene. The steps of its preparation method are as follows:

[0040] Take 1.24 kg of random copolymer polypropylene, 0.6 kg of block copolymer polypropylene, 0.02 kg of PP flow agent, and 0.14 kg of PP transparency enhancer. After mixing evenly, put them into a high-speed mixer and stir well at 25 ± 1 °C for 50 minutes. After the stirring is completed, carry out melting, mixing, extrusion, and pelletizing through a twin-screw extruder to obtain the special material for high melt index, low temperature resistant and impact resistant transparent polypropylene.

[0041] Example 6

[0042] This embodiment provides a high melt index, low temperature resistant, impact resistant, transparent polypropylene special material, the preparation method of which has the following steps:

[0043] Take 1.2kg of random copolymer polypropylene, 0.6kg of block copolymer polypropylene, 0.02kg of PP flow agent, and 0.18kg of PP permeability enhancer, mix them evenly and put them into a high-speed mixer, stir them thoroughly at 25±1℃ for 35 minutes, and after stirring, melt, mix, extrude and pelletize them through a twin-screw extruder to obtain a high melt index, low temperature resistant, impact resistant and transparent polypropylene special material.

[0044] Example 7

[0045] This embodiment provides a high melt index, low temperature resistant, impact resistant, transparent polypropylene special material, the preparation method of which has the following steps:

[0046] Take 1.41kg of random copolymer polypropylene, 0.47kg of block copolymer polypropylene, 0.02kg of PP flow agent and 0.1kg of PP permeability enhancer, mix them evenly and put them into a high-speed mixer, stir them thoroughly at 25±1°C for 40 minutes, melt and mix them through a twin-screw extruder after stirring, and pelletize the obtained product after extrusion to obtain a high melt index, low temperature resistant, impact resistant and transparent polypropylene special material.

[0047] Example 8

[0048] This embodiment provides a high melt index, low temperature resistant, impact resistant, transparent polypropylene special material, the preparation method of which has the following steps:

[0049] Take 1.053kg of random copolymer polypropylene, 0.527kg of block copolymer polypropylene, 0.3kg of elastomer modifier, 0.02kg of PP flow agent, and 0.1kg of PP permeability enhancer, mix them evenly and put them into a high-speed mixer, stir them thoroughly at 25±1°C for 50 minutes, and after stirring, melt, mix, extrude and pelletize them through a twin-screw extruder to obtain a high melt index, low temperature resistant, impact resistant and transparent polypropylene special material.

[0050] Comparative Example 1

[0051] This embodiment provides a high melt index, low temperature resistant, impact resistant, transparent polypropylene special material, the preparation method of which has the following steps:

[0052] Take 1.28kg of random copolymer polypropylene, 0.62kg of block copolymer polypropylene, and 0.1kg of PP permeability enhancer, mix them evenly and put them into a high-speed mixer, stir them thoroughly at 25±1℃ for 40 minutes, and after stirring, use a twin-screw extruder to melt, mix, extrude, and pelletize to obtain a high melt index, low temperature resistant, impact resistant, transparent polypropylene special material.

[0053] Comparative Example 2

[0054] This embodiment provides a special material for high melt index, low temperature resistant and impact resistant transparent polypropylene, and the steps of its preparation method are as follows:

[0055] Take 1.36 kg of random copolymer polypropylene, 0.62 kg of block copolymer polypropylene, and 0.1 kg of PP flow agent. After mixing evenly, put them into a high-speed mixer and stir well at 25 ± 1 °C for 45 minutes. After the stirring is completed, melt, mix, extrude, and pelletize through a twin-screw extruder to obtain a special material for high melt index, low temperature resistant and impact resistant transparent polypropylene.

[0056] Perform melt mass flow rate (MFR), light transmittance and haze, tensile properties, flexural properties, and notched Izod impact strength tests on the polypropylene special materials prepared in the above Examples 1-8 and Comparative Examples 1-2.

[0057] Among them, the melt mass flow rate (MFR) is tested according to GB / T 3682.1-2018, the light transmittance and haze are tested according to GB / T 2410-2008, the tensile properties are tested according to the national standard GB / T 1040.2-2022, the flexural properties are tested according to GB / T9341-2008, and the notched Izod impact strength test is tested according to the national standard GB / T 1043.1-2008. Among them, the test conditions for the melt mass flow rate: 230 °C, 2.16 kg; the test conditions for haze and light transmittance: the sample thickness is 2 mm; the test piece for elongation at break: sample 1B type, test speed 50 mm / min, gauge length 50 mm; the test conditions for flexural strength and flexural modulus: test speed 2 mm / min, span 64 mm; the test conditions for notched Izod impact strength: type 1 sample, A-type notch, span 62 mm, test temperature -23 °C, and place it at this temperature for 1 h. The test results are shown in Table 1.

[0058] Table 1. Performance test results of Examples 1-8 and Comparative Examples 1-2.

[0059] Sample <![CDATA[Melt mass flow rate (MFR / g·10min -1 )]]> Transmittance (%) Haze (%) Elongation at break (%) Flexural strength (Mpa) Flexural modulus (Mpa) <![CDATA[Notched impact strength of simply supported beam (kJ·m 2 )]]> Example 1 125.0 75.0 85.2 3.6 49.2 1556.0 1.2 Example 2 - 76.0 - - - - - Example 3 - 73.8 - - - - - Example 4 45.7 66.0 91.9 37.4 41.4 1377.0 2.1 Example 5 - - 93.7 - - - - Example 6 - - 93.4 - - - - Example 7 - 64.9 85.4 21.3 46.2 1603.0 1.5 Example 8 12.9 51.9 91.5 506.0 22.8 702.0 3.9 Comparative example 1 - 66.3 92.7 177.0 29.2 899.0 1.8 Comparative example 2 - 63.4 94.5 657.0 27.2 813.0 1.4

[0060] As can be seen from Table 1, by comparing Example 1 and Example 4, it can be seen that by adding PP-B and PP-R for melt blending as a common matrix, the elongation at break and the notched Izod impact strength at low temperature of the polypropylene special material can be significantly improved.

[0061] By comparing Example 4 with Comparative Examples 1-2, it can be seen that the addition of this PP flow agent and PP clarifier can both improve the flexural strength, flexural modulus and notched Izod impact strength at low temperature of the polypropylene special material.

[0062] It can be seen by comparing Example 1 and Example 8 that adding an elastomer modifier can greatly improve the elongation at break and the notched impact strength of the simple supported beam at low temperature of the special polypropylene material.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that after reading the specification of this application, the technicians can still modify the specific implementation manners of the present invention or make equivalent substitutions, but these modifications or changes are all within the protection scope of the pending claims of the present invention application.

Claims

1. A special material for high melt index, low temperature resistant and impact resistant transparent polypropylene, characterized in that, The special polypropylene material comprises the following components: 60-94 parts by weight of random copolymer polypropylene, 0-31 parts by weight of block copolymer polypropylene, 0-25 parts by weight of an elastomer modifier, 1-2 parts by weight of a PP flow agent, and 5-9 parts by weight of a PP transparency enhancer.

2. The high melt index low temperature resistant impact resistant transparent polypropylene special material according to claim 1, characterized in that, The special polypropylene material comprises the following components: 60-94 parts by weight of random copolymer polypropylene, 5-31 parts by weight of block copolymer polypropylene, 5-25 parts by weight of an elastomer modifier, 1-2 parts by weight of a PP flow agent, and 5-9 parts by weight of a PP transparency enhancer.

3. The high melt index low temperature resistant impact resistant transparent polypropylene special material according to claim 1, characterized in that, The melt index of the random copolymer polypropylene under the conditions of 230 °C / 2.16 kg is 55-65 g / 10 min, the tensile yield stress is 35.1 MPa, the flexural modulus is 1680 MPa, and the notched Izod impact strength at 23 °C is 1.4 kJ / m 2 .

4. The special-purpose material for high melt index, low-temperature resistant and impact-resistant transparent polypropylene according to claim 1, wherein The melt index of the block copolymer polypropylene under the conditions of 230°C / 2.16 kg is 1.0 to 2.0 g / 10 min, the tensile yield stress ≥ 22.0 MPa, the flexural modulus ≥ 900 MPa, and the notched Izod impact strength under the condition of 23°C ≥ 10 kJ / m 2 .

5. The high melt index low temperature resistant impact resistant transparent polypropylene special material according to claim 1, characterized in that, The PP flow agent is composed of 97-99 wt% polypropylene and 1-3 wt% di-tert-butyl peroxide, with a density of 0.93 g / cm 3 , and its melt index under the conditions of 230 °C / 2.16 kg is greater than 2000 g / 10 min, and its Vicat softening point is 152 °C.

6. The special-purpose material for high melt index, low-temperature resistant and impact-resistant transparent polypropylene according to claim 1, characterized in that, The melting point of the PP transparency enhancer is 180-230 °C.

7. The special-purpose material for high melt index low-temperature resistant impact-resistant transparent polypropylene according to claim 1, characterized in that, The elastomer modifier includes, but is not limited to, styrene-butadiene rubber.

8. The preparation method of the special material for high melt index low temperature resistant impact transparent polypropylene according to any one of claims 1 to 7, characterized in that, It includes the following steps: Mix the random copolymer polypropylene, block copolymer polypropylene, PP flow agent, elastomer modifier and PP transparency enhancer, stir, melt, knead, extrude and pelletize to obtain the special high melt index low temperature resistant impact transparent polypropylene material.

9. The preparation method of the special-purpose material for high melt index low-temperature resistant impact-resistant transparent polypropylene according to claim 8, characterized in that, The stirring time is 30-60 minutes, and the stirring temperature is 25±1 °C.

10. Application of the special polypropylene material according to any one of claims 1-7 or the special polypropylene material obtained by the preparation method according to any one of claims 8-9 in food packaging.