Impact-resistant and low-temperature-resistant plastic cup and preparation method thereof

Abstract

The invention discloses an impact-resistant and low-temperature-resistant plastic cup and a preparation method thereof, and belongs to the technical field of high polymer materials. The preparation method comprises the following steps: melting and plasticizing PPR, POE (Polyolefin Elastomer), LLDPE (Linear Low Density Polyethylene), EVA (Ethylene Vinyl Acetate) and a sorbitol nucleating agent, injecting into a mold, maintaining the pressure, pre-plasticizing and cooling to obtain the plastic cup. The POE and the LLDPE are added to jointly improve the notch impact strength of PPR, the light transmittance of the product is kept at 64.9%-67.3% through a proper raw material ratio, the actual production requirements are met, and the POE / LLDPE composite material is good in toughness and free of cracking at low temperature. The preparation method is suitable for preparing the plastic cup with impact resistance and low temperature resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials and relates to a plastic cup, in particular to an impact-resistant and low-temperature-resistant plastic cup and a preparation method thereof. Background Art

[0002] Water cups are usually made of glass, plastic, ceramic and other materials. Glass and ceramic water cups are not resistant to falling, while plastic water cups are more durable and have a variety of shapes, occupying a relatively large market. Plastic water cups are generally made of polypropylene (PP), polycarbonate (PC) or polyethylene terephthalate (PET) and other materials. Among them, polypropylene is non-toxic, odorless, tasteless, and light in texture. It is one of the lightest varieties of all plastics at present, and has good heat resistance. The products can be sterilized at temperatures above 100°C.

[0003] However, the general notched impact strength of random copolymer polypropylene (PPR) is 50-60J / m, which cannot meet the product drop quality standard when the product capacity is large. Usually, this problem can be solved by adding POE plastic, but POE plastic is expensive and will greatly reduce the transparency of the product, which does not meet the actual production needs. In addition, PPR has poor low-temperature toughness and is prone to cracking in low-temperature environments. Summary of the invention

[0004] The purpose of the present invention is to provide an impact-resistant and low-temperature-resistant plastic cup and a preparation method thereof, so as to solve the problems of poor impact resistance and low-temperature resistance of existing polypropylene plastic cups.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] The invention discloses an impact-resistant and low-temperature-resistant plastic cup. The raw materials for making the plastic cup include, by weight, 100 parts of PPR, 10-15 parts of POE, 5-10 parts of LLDPE, 10 parts of EVA and 0.2-0.4 parts of a sorbitol nucleating agent.

[0007] As a limitation, the content of vinyl acetate in the EVA is between 10wt% and 20wt%.

[0008] As another limitation, the sorbitol-based nucleating agent includes Millad 3988 and / or Millad NX8000.

[0009] The present invention also provides a method for preparing the impact-resistant and low-temperature-resistant plastic cup, which comprises the steps of melting and plasticizing the raw materials, injecting the raw materials into a mold, maintaining pressure, pre-plasticizing, and cooling to obtain the plastic cup.

[0010] As a limitation, during the melt plasticization, the temperature of zone one is 210-250°C, the temperature of zone two is 225-265°C, and the temperature of zone three is 225-265°C.

[0011] As another limitation, the injection has a pressure of 100-120 bar, a speed of 75-115 mm / s, and a time of 0.33 s.

[0012] As a third limitation, the pressure maintaining is 75-95 bar and the time is 0.9 s.

[0013] As a fourth limitation, the pre-plasticization has a back pressure of 8 bar, a time of 1-3 s, a position of 100-110 mm, and a speed of 78-118 mm / s.

[0014] As a fifth limitation, the cooling is performed at a temperature of 8-22°C, a pressure of 0.4-0.8 MPa, and a time of 3-5 s.

[0015] Due to the adoption of the above technical solution, the present invention has the following technical advances compared with the prior art:

[0016] ① The impact-resistant and low-temperature-resistant plastic cup provided by the present invention improves the notched impact strength of PPR by adding POE and LLDPE. Since POE and LLDPE will cause the rigidity of the product to deteriorate, a sorbitol nucleating agent is added to increase the rigidity and light transmittance of the product. Through a suitable raw material ratio, the product can maintain a light transmittance of 64.9%-67.3% while improving the impact resistance, meeting the actual production needs, and having good toughness at low temperatures without cracking;

[0017] ② The impact-resistant and low-temperature-resistant plastic cup provided by the present invention has the following problems: since the addition of POE and LLDPE will lead to poor fluidity, high viscosity, difficulty in demoulding, and poor product dimensional stability of the mixture in the mold, EVA is added to the formula. EVA has good compatibility with PPR, and high melt index EVA has the effect of increasing surface smoothness. When the content of vinyl acetate is 10wt%-20wt%, EVA has excellent smoothness, excellent low-temperature resistance, and high notched impact strength. The addition of EVA improves the surface smoothness of the overall system without reducing rigidity and toughness, thereby making demoulding easier and significantly improving product dimensional stability;

[0018] ③ The invention provides a method for preparing an impact-resistant and low-temperature-resistant plastic cup, which has a simple preparation process and is suitable for industrial production. DETAILED DESCRIPTION

[0019] The present invention is further described in detail below by specific examples. It should be understood that the described examples are only used to explain the present invention, and are not intended to limit the present invention.

[0020] Unless otherwise specified, the experimental methods used in the following examples are conventional methods in the art.

[0021] In the following embodiments, PPR was purchased from North Huajin Chemical Industry Group Co., Ltd., model RC-20M; POE was purchased from ExxonMobil, model 6202; LLDPE was purchased from ExxonMobil, model 6101; EVA model was E156W; sorbitol nucleating agents were purchased from Milliken & Company, models Millad 3988 and Millad NX8000.

[0022] Example 1

[0023] This embodiment prepares an impact-resistant and low-temperature-resistant plastic cup and verifies its relevant properties, which specifically includes the following steps:

[0024] Take 100kg of PPR, 15kg of POE, 10kg of LLDPE, 10kg of EVA (vinyl acetate content is 10wt%), and 0.2kg of sorbitol nucleating agent Millad 3988, add the raw materials into the barrel for melt plasticization (wherein the temperature of zone 1 is 230°C, the temperature of zone 2 is 245°C, and the temperature of zone 3 is 245°C), then take a 760 cup mold for mold closing, and then inject the molten raw material at a pressure of 110bar and a speed of 95mm / s for 0.33s, so that the raw material enters the mold, maintains the pressure at a pressure of 85bar for 0.9s, pre-plasticizes under the conditions of back pressure of 8bar, time of 2s, position of 105mm, and speed of 98mm / s, and then cools for 4s at 15°C and 0.4Mpa to obtain a plastic cup;

[0025] A plastic cup was placed in a climate chamber ETH100L (purchased from Ningbo Edison Instrument Co., Ltd.) at 20°C, 10°C, 0°C, -10°C, and -20°C for 24 hours, then taken out and filled with water (total weight 850 g). The mouth of the cup was covered with a sealing film, and the cup was dropped vertically from the ground at a height of 0.8m and 1.2m for ten times to test the normal and low temperature impact performance of the plastic cup.

[0026] The transmittance tester LS116 (purchased from Shenzhen Linshang Technology Co., Ltd.) was used to test the transmittance of the plastic cup. The results are shown in Table 1:

[0027] Table 1 Impact resistance and light transmittance test results

[0028]

[0029] The free fall drop test simulates the possible situations that may occur during the logistics and transportation of products. The smaller the friction between the contents and the cup wall, the greater the actual impact force of the drop. Therefore, the impact force of a full cup of water is much greater than that of a full cup of yogurt or other substances. As shown in Table 1, the plastic cup meets the actual use requirements (usually, after being placed at 0℃ for 24 hours and then dropped three times at 0.8m, it meets the requirements without cracking. Under normal logistics and transportation conditions in winter, cracking basically does not occur).

[0030] Example 2

[0031] This embodiment prepares an impact-resistant and low-temperature-resistant plastic cup and verifies its relevant properties, which specifically includes the following steps:

[0032] Take 100kg of PPR, 10kg of POE, 5kg of LLDPE, 10kg of EVA (vinyl acetate content is 20wt%) and 0.4kg of sorbitol nucleating agent Millad NX8000, add the raw materials into the barrel for melt plasticization (wherein the temperature of zone one is 210°C, the temperature of zone two is 225°C, and the temperature of zone three is 265°C), then take a 760 cup mold for mold closing, and then inject the molten raw material at a pressure of 100bar and a speed of 115mm / s for 0.33s to make the raw material enter the mold, maintain the pressure at a pressure of 75bar for 0.9s, pre-plasticize under the conditions of back pressure of 8bar, time of 1s, position of 110mm, and speed of 78mm / s, and then cool for 5s at 8°C and 0.6Mpa to obtain a plastic cup. After simulation testing, the plastic cup meets the actual use requirements.

[0033] Example 3

[0034] This embodiment prepares an impact-resistant and low-temperature-resistant plastic cup and verifies its relevant properties, which specifically includes the following steps:

[0035] Take 100kg of PPR, 13kg of POE, 8kg of LLDPE, 10kg of EVA (vinyl acetate content is 15wt%) and 0.15kg of sorbitol nucleating agent Millad 3988 and 0.15kg of sorbitol nucleating agent Millad NX8000, puts the raw materials into the barrel for melting and plasticization (wherein the temperature of zone 1 is 250℃, the temperature of zone 2 is 265℃, and the temperature of zone 3 is 225℃), then takes the 760 cup mold for mold closing, and then injects the molten raw materials at a speed of 75mm / s for 0.33s under a pressure of 120bar, so that the raw materials enter the mold, and maintains the pressure at a pressure of 95bar for 0.9s, and pre-plasticizes under the conditions of back pressure of 8bar, time of 3s, position of 100mm, and speed of 118mm / s, and then cools for 3s at 22℃ and 0.8Mpa to obtain a plastic cup. After simulation testing, the plastic cup meets the actual use requirements.

Claims

1. An impact-resistant and low-temperature-resistant plastic cup, characterized in that: The raw materials for making the said composite material include, by weight, 100 parts of PPR, 10-15 parts of POE, 5-10 parts of LLDPE, 10 parts of EVA and 0.2-0.4 parts of a sorbitol nucleating agent.

2. The impact-resistant and low-temperature-resistant plastic cup according to claim 1, characterized in that: The content of vinyl acetate in the EVA is 10wt%-20wt%.

3. An impact-resistant and low-temperature-resistant plastic cup according to claim 1 or 2, characterized in that: The sorbitol nucleating agent includes Millad 3988 and / or Millad NX8000.

4. A method for preparing an impact-resistant and low-temperature-resistant plastic cup according to any one of claims 1 to 3, characterized in that: The process comprises the steps of melting and plasticizing the raw materials, injecting the raw materials into a mold, maintaining pressure, pre-plasticizing, and cooling to obtain a plastic cup.

5. The method for preparing a shock-resistant and low-temperature-resistant plastic cup according to claim 4, characterized in that: During the melt plasticization, the temperature of zone 1 is 210-250°C, the temperature of zone 2 is 225-265°C, and the temperature of zone 3 is 225-265°C.

6. The method for preparing a shock-resistant and low-temperature-resistant plastic cup according to claim 4 or 5, characterized in that: The injection pressure is 100-120 bar, the speed is 75-115 mm / s, and the time is 0.33 s.

7. A method for preparing an impact-resistant and low-temperature-resistant plastic cup according to claim 4 or 5, characterized in that: The pressure is maintained at 75-95 bar and the time is 0.9 s.

8. The method for preparing a shock-resistant and low-temperature-resistant plastic cup according to claim 4 or 5, characterized in that: The pre-plasticization has a back pressure of 8 bar, a time of 1-3 s, a position of 100-110 mm, and a speed of 78-118 mm / s.

9. The method for preparing a shock-resistant and low-temperature-resistant plastic cup according to claim 4 or 5, characterized in that: The cooling process has a temperature of 8-22° C., a pressure of 0.4-0.8 MPa, and a time of 3-5 seconds.

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