A special polypropylene material for frosted cups and its preparation method

Abstract

The present invention provides a special polypropylene material for frosted cups and a preparation method thereof. In terms of parts by weight, the raw materials include: 100 parts of ethylene-propylene random copolymer polypropylene resin; 0.01-0.02 parts of nucleating agent; 0.1-0.3 parts of antioxidant; 0.01-0.2 parts of halogen absorber; the nucleating agent is selected from at least one of polyvinylcyclopentane, polyvinylcyclohexane, polyvinyl-2-methylcyclohexane, poly-3-methyl-1-butene, poly-3-ethyl-1-hexene, poly-3-methyl-1-pentene and polystyrene. By adopting a specific type of nucleating agent, the special polypropylene material for frosted cups of the present invention has excellent low-temperature impact performance and high crystallization rate. The experimental results show that the crystallization temperature of the special polypropylene material for frosted cups is 115.9-118.0 °C, and the notched Izod impact strength at -20 °C is 1.6-1.7 kJ / m 2 .

Description

Technical Field

[0001] The present invention belongs to the technical field of milk tea cup materials, and particularly relates to a special polypropylene material for frosted cups and a preparation method thereof. Background Art

[0002] Polypropylene milk tea cups have the characteristics of being transparent, light, having good heat resistance and good stability. According to different shapes, they can be divided into high-transparency cups and frosted cups. Polypropylene frosted cups have become a very popular product in the market at present due to their good sensory performance.

[0003] However, due to the relatively high crystallinity of polypropylene, its glass transition is around -10°C, so the low-temperature impact resistance of ordinary polypropylene is poor. Especially under freezing conditions, polypropylene is prone to environmental cracking (because it is in the glass transition range); at the same time, because polypropylene has a relatively high crystallinity and a slow crystallization rate, during the molding process of polypropylene products, a certain molding cycle is required to ensure complete crystallization of polypropylene. If the molding cycle is too short, the polypropylene will not crystallize completely, and the product is prone to warping and deformation problems. The molding cycle of the product determined by the crystallization performance of polypropylene will directly affect the production cost of downstream products.

[0004] The current polypropylene frosted cups are prepared by using high-melt-index random copolymer polypropylene (PPR) as raw materials. Although PPR has better impact resistance than ordinary homopolypropylene, the low-temperature impact performance of this PPR frosted cup is still very poor; in order to improve the crystallization performance of PPR, increase its crystallization rate, and shorten the molding cycle of frosted cup products, usually a small molecule nucleating agent (such as Milliken HPN-20E) is added during the processing of PPR to improve its crystallization performance, but the addition cost of 500 ppm is relatively high, and the advantage compared to polypropylene is not obvious. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a special polypropylene material for frosted cups and a preparation method thereof, which has a fast crystallization rate and excellent low-temperature impact performance.

[0006] The present invention provides a special polypropylene material for frosted cups, which comprises the following raw materials in parts by weight:

[0007] 100 parts of ethylene-propylene random copolymer polypropylene resin; 0.01 - 0.02 parts of nucleating agent; 0.1 - 0.3 parts of antioxidant; 0.01 - 0.2 parts of halogen absorbent;

[0008] The nucleating agent is selected from at least one of polyvinylcyclopentane, polyvinylcyclohexane, polyvinyl-2-methylcyclohexane, poly-3-methyl-1-butene, poly-3-ethyl-1-hexene, poly-3-methyl-1-pentene and polystyrene.

[0009] Preferably, the ethylene content in the ethylene-propylene random copolymer polypropylene resin is 2.5-3.0%, and the melt index at 230°C / 2.16 kg is 60-80 g / 10 min.

[0010] Preferably, the antioxidant is selected from the mixture of a primary antioxidant and a co-antioxidant with a mass ratio of 1:(1-4);

[0011] The primary antioxidant is selected from one or more of antioxidant 2246, antioxidant 1010, antioxidant 1076, and antioxidant 1330;

[0012] The co-antioxidant is selected from one or more of antioxidant 168, antioxidant 626, and antioxidant 9228.

[0013] Preferably, the halogen absorber is selected from one or more of sodium stearate, calcium stearate, and zinc stearate.

[0014] Preferably, the antioxidant is a mixture of antioxidant 1010 and antioxidant 168 with a mass ratio of 1:2.

[0015] Preferably, the antioxidant is 0.1-0.2 parts.

[0016] Preferably, the halogen absorber is 0.03-0.1 parts.

[0017] Preferably, the crystallization temperature of the special polypropylene material for the frosted cup > 115°C; the notched Izod impact strength at -20°C > 1.5 KJ / m 2 。

[0018] The present invention provides a preparation method of the special polypropylene material for the frosted cup described in the above technical solution, including the following steps:

[0019] Mix the ethylene-propylene random copolymer polypropylene resin, nucleating agent, antioxidant, and halogen absorber, and extrude and pelletize to obtain the special polypropylene material for the frosted cup;

[0020] The temperature of each section of the screw is 170-235°C, and the highest temperature exceeds 230°C.

[0021] Preferably, the temperature in each zone during extrusion: zone 1 is 170°C, zone 2 is 190°C, zone 3 is 210°C, zone 4 is 235°C, zone 5 is 200°C, and the die head is 180°C.

[0022] The present invention provides a special polypropylene material for frosted cups, which comprises the following raw materials in parts by weight: 100 parts of ethylene-propylene random copolymer polypropylene resin; 0.01 to 0.02 parts of a nucleating agent; 0.1 to 0.3 parts of an antioxidant; 0.01 to 0.2 parts of a halogen absorber; the nucleating agent is selected from at least one of vinylcyclopentane, vinylcyclohexane, vinyl-2-methylcyclohexane, poly(3-methyl-1-butene), poly(3-ethyl-1-hexene), poly(3-methyl-1-pentene) and polystyrene. By adopting a specific type of nucleating agent, the special polypropylene material for frosted cups of the present invention has excellent low-temperature impact performance and high crystallization rate. Detailed Embodiments

[0023] The present invention provides a special polypropylene material for frosted cups, which comprises the following raw materials in parts by weight:

[0024] 100 parts of ethylene-propylene random copolymer polypropylene resin; 0.01 to 0.02 parts of a nucleating agent; 0.1 to 0.3 parts of an antioxidant; 0.01 to 0.2 parts of a halogen absorber;

[0025] The nucleating agent is selected from at least one of vinylcyclopentane, vinylcyclohexane, vinyl-2-methylcyclohexane, poly(3-methyl-1-butene), poly(3-ethyl-1-hexene), poly(3-methyl-1-pentene) and polystyrene.

[0026] The special polypropylene material for frosted cups provided by the present invention comprises 100 parts of ethylene-propylene random copolymer polypropylene resin. In the present invention, the ethylene content in the ethylene-propylene random copolymer polypropylene resin is 2.5 to 3.0 wt%, and the melt index at 230 °C / 2.16 kg is 60 to 80 g / 10 min.

[0027] The special polypropylene material for frosted cups provided by the present invention comprises 0.01 to 0.02 parts of a nucleating agent; the specific amounts are 0.01 part, 0.011 part, 0.012 part, 0.013 part, 0.014 part, 0.015 part, 0.016 part, 0.017 part, 0.018 part, 0.019 part or 0.020 part. The nucleating agent is selected from at least one of vinylcyclopentane, vinylcyclohexane (PVCH), vinyl-2-methylcyclohexane, poly(3-methyl-1-butene), poly(3-ethyl-1-hexene), poly(3-methyl-1-pentene) and polystyrene; in a specific embodiment, the nucleating agent is poly(3-methyl-1-butene); or a mixture of vinylcyclohexane and poly(3-methyl-1-butene) with a mass ratio of 3:1. The nucleating agent is preferably prepared by itself by the method disclosed in CN202410183936.6.

[0028] The special polypropylene material for frosted cups provided by the present invention includes 0.1 to 0.3 parts of antioxidant, preferably 0.1 to 0.2 parts; the specific dosage is 0.1 part, 0.11 part, 0.12 part, 0.13 part, 0.14 part, 0.15 part, 0.16 part, 0.17 part, 0.18 part, 0.19 part or 0.20 part. The antioxidant is selected from the mixture of a primary antioxidant and a co-antioxidant with a mass ratio of 1:(1 - 4); the primary antioxidant is selected from one or more of antioxidant 2246, antioxidant 1010, antioxidant 1076 and antioxidant 1330; the co-antioxidant is selected from one or more of antioxidant 168, antioxidant 626 and antioxidant 9228. In the present invention, the antioxidant is preferably a mixture of antioxidant 1010 and antioxidant 168 with a mass ratio of 1:2.

[0029] The special polypropylene material for frosted cups provided by the present invention includes 0.01 to 0.2 parts of halogen absorber, preferably 0.03 to 0.1 part; the specific dosage is 0.03 part, 0.04 part, 0.05 part, 0.06 part, 0.07 part, 0.08 part, 0.09 part or 0.10 part. The halogen absorber is selected from one or more of sodium stearate, calcium stearate and zinc stearate.

[0030] The crystallization temperature of the special polypropylene material for frosted cups provided by the present invention is > 115°C; the notched Izod impact strength at -20°C is > 1.5 KJ / m 2 。

[0031] The present invention provides a preparation method of the special polypropylene material for frosted cups as described in the above technical solution, including the following steps:

[0032] Mix the ethylene-propylene random copolymer polypropylene resin, nucleating agent, antioxidant and halogen absorber, and extrude and pelletize to obtain the special polypropylene material for frosted cups;

[0033] The temperature of each section of the screw is 170 - 235°C, and the highest temperature exceeds 230°C.

[0034] The present invention preferably premixes the raw materials in a high-speed mixer; the mixed materials are fed into a twin-screw extruder by a feeder. The materials are sheared and blended by the twin-screw extruder and then extruded from the head, and are pelletized, air-cooled, cut into pellets, dried and then packaged.

[0035] In the specific embodiments of the present invention, the temperature in each section during extrusion: the first zone is 170°C, the second zone is 190°C, the third zone is 210°C, the fourth zone is 235°C, the fifth zone is 200°C, and the head is 180°C.

[0036] To further illustrate the present invention, the following examples are used to describe in detail a special polypropylene material for frosted cups and its preparation method provided by the present invention, but they should not be construed as limiting the protection scope of the present invention.

[0037] Example 1

[0038] Weigh the materials according to the components and formula provided in Table 1 (by weight, the percentages are all mass percentages, the same as in the following examples, PVCH is polyvinylcyclohexane). After mixing in a high-speed mixer for 5 minutes, extrude and pelletize in a twin-screw extruder with a length-diameter ratio of 60:1 and a diameter of 35 mm to obtain the special material for frosted cups made of polypropylene; the temperatures of each zone of the extruder are: Zone 1 170°C, Zone 2 190°C, Zone 3 210°C, Zone 4 235°C, Zone 5 200°C, the head 180°C, the rotation speed 400 r / min, and the melt pressure 3 MPa.

[0039] Table 1 Components, formula and processing conditions of examples and comparative examples

[0040]

[0041]

[0042] Example 2

[0043] The difference between Example 2 and Example 1 is only the dosage of the polymer nucleating agent used. The polymer nucleating agent used in Example 2 is 0.02 parts by weight.

[0044] Example 3

[0045] The difference between Example 3 and Example 1 is only the type of the polymer nucleating agent used. The polymer nucleating agent used in Example 3 is poly(3-methyl-1-butene).

[0046] Example 4

[0047] The difference between Example 4 and Example 2 is only the type of the polymer nucleating agent used. The polymer nucleating agent used in Example 4 is poly(3-methyl-1-butene).

[0048] Example 5

[0049] The difference between Example 5 and Example 1 is only the dosage and type of the polymer nucleating agent used. The polymer nucleating agents used in Example 5 are 0.015 parts by weight of PVCH and 0.005 parts by weight of poly(3-methyl-1-butene).

[0050] Comparative Example 1

[0051] The difference between Comparative Example 1 and Example 1 is only that the highest granulation temperature of the extruder is 200°C, and the temperatures of each zone of the extruder are: Zone 1 170°C, Zone 2 180°C, Zone 3 190°C, Zone 4 200°C, Zone 5 180°C, the head 180°C.

[0052] Comparative Example 2

[0053] The difference between Comparative Example 2 and Example 1 lies only in that the nucleating agent used is a small molecule nucleating agent, and the nucleating agent used in Comparative Example 2 is Milliken HPN-20E nucleating agent.

[0054] Comparative Example 3

[0055] The difference between Comparative Example 3 and Comparative Example 2 lies only in the different dosages of the small molecule nucleating agent. The dosage of Comparative Example 3 is 0.05 parts by weight.

[0056] The performance test results of the special polypropylene material for frosted cups prepared in the examples and comparative examples are shown in Table 2:

[0057] Table 2 Performance of the materials produced in the examples and comparative examples

[0058]

[0059] The crystallization temperature is a good indicator of the nucleating agent efficiency. A higher crystallization temperature means more effective nucleation in the final product. The difference between the initial crystallization temperature and the crystallization temperature can reflect the crystallization speed of the material. The smaller the difference, the faster the crystallization speed and the shorter the molding cycle of the product. It can be seen from the data comparison that Examples 1-5 have a higher crystallization temperature and a smaller difference between the initial crystallization temperature and the crystallization temperature than Comparative Examples 1-3, indicating that the materials of the present invention have the characteristics of fast crystallization speed and short molding cycle of the product.

[0060] The notched Izod impact strength at -20 °C represents the low-temperature impact performance. It can be seen from the data that the materials of the present invention have excellent low-temperature impact performance.

[0061] The comparison between Comparative Example 1 and Example 1 can illustrate the importance of selecting the highest granulation temperature of 235 °C. The material properties prepared by granulation at 235 °C are significantly better than those prepared by granulation at 200 °C. (Note: The fundamental reason is that the melting points of polymer nucleating agents are generally relatively high, generally >200 °C. If the granulation temperature is too low, the dispersion effect of the nucleating agent in the melt is not good.)

[0062] It can be seen from the comparison of Example 1, Example 3 and Comparative Example 2, Comparative Example 3 that the effect of 100 ppm polymer nucleating agent is better than that of 500 ppm small molecule nucleating agent.

[0063] As can be seen from the above embodiments, the present invention provides a special polypropylene material for frosted cups, which comprises the following raw materials in parts by weight: 100 parts of ethylene-propylene random copolymer polypropylene resin; 0.01 to 0.02 parts of a nucleating agent; 0.1 to 0.3 parts of an antioxidant; 0.01 to 0.2 parts of a halogen absorbent; the nucleating agent is selected from at least one of polyvinylcyclopentane, polyvinylcyclohexane, polyvinyl-2-methylcyclohexane, poly-3-methyl-1-butene, poly-3-ethyl-1-hexene, poly-3-methyl-1-pentene and polystyrene. By adopting a specific type of nucleating agent, the special polypropylene material for frosted cups of the present invention has excellent low-temperature impact performance and high crystallization rate. The experimental results show that: the crystallization temperature of the special polypropylene material for frosted cups is 115.9 to 118.0 °C, and the notched Izod impact strength at -20 °C is 1.6 to 1.7 kJ / m 2 .

[0064] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A special polypropylene material for frosted cups, comprising the following raw materials in parts by weight: 100 parts of ethylene-propylene random copolymer polypropylene resin; 0.01-0.02 parts of nucleating agent; 0.1-0.3 parts of antioxidant; 0.01-0.2 parts of halogen absorbent; The nucleating agent is a mixture of polyvinyl cyclohexane and poly 3-methyl-1-butene in a mass ratio of 3:1; The preparation method of the special polypropylene material for frosted cups comprises the following steps: The ethylene-propylene random copolymer polypropylene resin, a nucleating agent, an antioxidant and a halogen absorbent are mixed, extruded and granulated to obtain a special polypropylene material for frosted cups; The temperature of each screw section is 170~235℃, and the highest temperature exceeds 230℃.

2. The special polypropylene material for frosted cups according to claim 1, characterized in that The ethylene content of the ethylene-propylene random copolymer polypropylene resin is 2.5-3.0%, and the melting index at 230°C / 2.16kg is 60-80g / 10min.

3. The special polypropylene material for frosted cups according to claim 1, wherein The antioxidant is selected from a mixture of a primary antioxidant and a secondary antioxidant in a mass ratio of 1:(1-4); The primary antioxidant is selected from one or more of antioxidant 2246, antioxidant 1010, antioxidant 1076 and antioxidant 1330; The auxiliary antioxidant is selected from one or more of antioxidant 168, antioxidant 626 and antioxidant 9228.

4. The special polypropylene material for frosted cups according to claim 1, characterized in that, The halogen absorbent is selected from one or more of sodium stearate, calcium stearate and zinc stearate.

5. The special polypropylene material for frosted cups according to claim 1, wherein The antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:

2.

6. The special polypropylene material for frosted cups according to claim 1, wherein Antioxidant 0.1~0.2 parts.

7. The special polypropylene material for frosted cups according to claim 1, wherein 0.03~0.1 parts of halogen absorbent.

8. The special polypropylene material for frosted cups according to claim 1, characterized in that, The crystallization temperature of the special polypropylene material for frosted cups > 115°C; the notched Izod impact strength at -20°C > 1.5 KJ / m 2 .

9. A method for preparing the polypropylene special material for frosted cups according to claim 1, comprising the following steps: The ethylene-propylene random copolymer polypropylene resin, a nucleating agent, an antioxidant and a halogen absorbent are mixed, extruded and granulated to obtain a special polypropylene material for frosted cups; The temperature of each screw section is 170~235℃, and the highest temperature exceeds 230℃.

10. The preparation method according to claim 9, characterized in that, The temperature of each zone during extrusion: zone 1 170℃, zone 2 190℃, zone 3 210℃, zone 4 235℃, zone 5 200℃, die head 180℃.

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