A modified polyethylene plastic and its application in preparing high-strength trash can

Abstract

The invention relates to the technical field of polyethylene plastics, and discloses a modified polyethylene plastic and an application thereof in preparing a high-strength garbage can. The raw materials for preparing the modified polyethylene plastic include 70-90 parts by weight of polyethylene resin, 10-30 parts by weight of modified nitrile rubber, 1-8 parts by weight of TDI modified montmorillonite, and 0.3-0.5 parts by weight of an antioxidant. Long-chain alkyl and hydroxyl groups are introduced into the side chain of the modified nitrile rubber, so that the nitrile rubber and the polyethylene resin have better compatibility, and the hydroxyl group can react with the isocyanate group of the TDI modified montmorillonite, so that the compatibility and interface bonding strength between the montmorillonite and the nitrile rubber are improved, so that the montmorillonite is evenly dispersed in the polyethylene / nitrile rubber composite material, and the mechanical properties of the material such as tensile strength are significantly improved.

Description

Technical Field

[0001] The invention relates to the technical field of polyethylene plastics, in particular to a modified polyethylene plastic and application thereof in preparing a high-strength garbage can. Background Art

[0002] Polyethylene is a common thermoplastic plastic that is non-toxic and odorless, has good solvent resistance, excellent electrical insulation, and is easy to process and shape. It can be made into products such as trash cans, plastic bags, TV shells, wires and cables, and pipes and tubes. It is widely used in industrial production and daily life. Nitrile rubber has excellent elasticity, strength and other mechanical properties. Polyethylene and nitrile rubber can be blended to form a composite material with excellent performance.

[0003] Adding inorganic nanomaterials such as montmorillonite, graphene, and silica to polyethylene can further improve the comprehensive performance of polyethylene materials. Patent CN106496735B discloses a method for preparing graphene oxide / nitrile rubber modified high-density polyethylene for 3D printing, wherein powdered nitrile rubber, modified graphene oxide suspension, and silane coupling agent are reacted to obtain modified graphene oxide / powdered nitrile rubber, which is then extruded and granulated with high-density polyethylene, dispersant, and compatibilizer to obtain modified high-density polyethylene with better mechanical properties. However, the graphene oxide in this patent is relatively expensive, and this patent requires the additional addition of silane coupling agent, dispersant, compatibilizer and other additives. Summary of the invention

[0004] The technical problem solved by the invention is to provide a modified polyethylene plastic with high mechanical properties.

[0005] The technical scheme of the present invention is: a modified polyethylene plastic, comprising 70-90 parts by weight of polyethylene resin, 10-30 parts by weight of modified nitrile rubber, 1-8 parts by weight of TDI modified montmorillonite, and 0.3-0.5 parts by weight of antioxidant.

[0006] The preparation method of modified nitrile rubber is:

[0007] Adding nitrile rubber, acrylate modifier and dibenzoyl peroxide into a torque rheometer for melt grafting, extracting the product with acetone in a Soxhlet extractor after cooling, heating under reflux during extraction, and then drying the product to obtain modified nitrile rubber.

[0008] The general structural formula of the acrylate modifier is as follows: n is any integer between 14 and 18.

[0009] Preferably, the mass of the acrylate modifier and dibenzoyl peroxide are 5-20% and 0.15-0.64% of the mass of the nitrile rubber, respectively.

[0010] Preferably, the temperature during melt grafting is 170-175° C. and the time is 10-30 min.

[0011] Preferably, the preparation method of the acrylate modifier is: add dichloromethane or chloroform cosolvent to tetrahydrofuran or ethanol solvent, the volume ratio of the two is 1: (0.3-0.5), add glycidyl methacrylate and alkylamine, heat to 40-50°C, stir and react for 4-6h, distill under reduced pressure, wash with petroleum ether, and recrystallize the product in dichloromethane to obtain the acrylate modifier. The reaction formula is as follows:

[0012]

[0013] Preferably, the molar amount of the alkylamine is 100-110% of the molar amount of the glycidyl methacrylate.

[0014] Preferably, the general structural formula of the alkylamine is H2N-C n H 2n+1 , n is any integer between 14 and 18.

[0015] Preferably, the preparation method of TDI-modified montmorillonite is: adding dry montmorillonite and toluene-2,4-diisocyanate to toluene, heating and stirring to react, filtering, washing with acetone, and drying to obtain TDI-modified montmorillonite.

[0016] Preferably, the preparation method of the modified polyethylene plastic is: polyethylene resin, modified nitrile rubber, TDI modified montmorillonite, and antioxidant are added to a twin-screw extruder, the melt extrusion temperature is 185-195°C, the screw speed is 50-100r / min, extrusion granulation, injection molding, and the modified polyethylene plastic is obtained.

[0017] Preferably, the modified polyethylene plastic is prepared for use in high-strength trash cans.

[0018] The technical effect of the present invention is that the nitrile rubber is melt-grafted and modified by using an acrylate modifier containing a long-chain alkyl group and a hydroxyl group, and a long-chain alkyl group and a hydroxyl group are introduced into the side chain of the nitrile rubber. The long carbon alkyl chain has a similar alkyl chain structure to polyethylene, so that the nitrile rubber and the polyethylene resin have better compatibility. After melt blending with polyethylene, the mechanical properties of the material such as tensile strength and impact strength are significantly improved.

[0019] After the montmorillonite of the present invention is organically modified by toluene-2,4-diisocyanate, it has better compatibility with polyethylene resin, and at the same time, isocyanate groups are introduced on the surface. During the melt blending process, the isocyanate groups can react with the hydroxyl groups of the side chains of the nitrile rubber, thereby improving the compatibility and interface bonding strength between the montmorillonite and the nitrile rubber, making the montmorillonite uniformly dispersed in the polyethylene / nitrile rubber composite material, and further improving the mechanical properties of the material such as tensile strength. The modified polyethylene plastic of the present invention can be made into high-strength plastic products, and has good practical applications in products such as garbage cans, plastic bags, TV housings, wires and cables, and pipelines. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below with reference to the embodiments.

[0021] Example 1

[0022] (1) Add 10 mL of dichloromethane as a cosolvent to 30 mL of tetrahydrofuran solvent, add 30 mmol of glycidyl methacrylate and 30 mmol of octadecylamine, heat to 45° C., stir to react for 6 h, distill under reduced pressure, wash with petroleum ether, and recrystallize the product in dichloromethane to obtain an acrylate modifier.

[0023] (2) 20 g of nitrile rubber, 2.5 g of acrylate modifier, and 0.08 g of dibenzoyl peroxide were added to a torque rheometer and melt grafted at 175° C. for 20 min. After cooling, the product was extracted with acetone in a Soxhlet extractor and heated under reflux during extraction. The product was then dried to obtain a modified nitrile rubber.

[0024] (3) 10 g of montmorillonite was dried at 250 °C for 2 h, added to 400 mL of toluene and 4 g of toluene-2,4-diisocyanate, heated to 80 °C, stirred for reaction for 2 h, filtered, washed with acetone, and dried to obtain TDI-modified montmorillonite.

[0025] (4) 900 g of polyethylene resin, 100 g of modified nitrile rubber, 10 g of TDI-modified montmorillonite, and 3 g of antioxidant 168 were added to a twin-screw extruder. The melt extrusion temperature was 195° C., the screw speed was 50 r / min, extrusion granulation was performed, and injection molding was performed to obtain modified polyethylene plastic.

[0026] Example 2

[0027] (1) Add 15 mL of trichloromethane as a cosolvent to 30 mL of tetrahydrofuran solvent, add 30 mmol of glycidyl methacrylate and 33 mmol of tetradecylamine, heat to 40° C., stir to react for 6 h, distill under reduced pressure, wash with petroleum ether, and recrystallize the product in dichloromethane to obtain an acrylate modifier.

[0028] (2) 20 g of nitrile rubber, 4 g of acrylate modifier, and 0.128 g of dibenzoyl peroxide were added to a torque rheometer and melt grafted at 170° C. for 30 min. After cooling, the product was extracted with acetone in a Soxhlet extractor and heated under reflux during extraction. The product was then dried to obtain a modified nitrile rubber.

[0029] (3) 800 g of polyethylene resin, 200 g of modified nitrile rubber, 50 g of TDI-modified montmorillonite (prepared in Example 1), and 5 g of antioxidant 168 were added to a twin-screw extruder. The melt extrusion temperature was 195° C., the screw speed was 50 r / min, and extrusion granulation and injection molding were performed to obtain modified polyethylene plastic.

[0030] Example 3

[0031] (1) Add 9 mL of dichloromethane as a cosolvent to 30 mL of ethanol solvent, add 30 mmol of glycidyl methacrylate and 30 mmol of hexadecylamine, heat to 50° C., stir to react for 4 h, distill under reduced pressure, wash with petroleum ether, and recrystallize the product in dichloromethane to obtain an acrylate modifier.

[0032] (2) 20 g of nitrile rubber, 1 g of acrylate modifier, and 0.03 g of dibenzoyl peroxide were added to a torque rheometer and melt grafted at 175° C. for 10 min. After cooling, the product was extracted with acetone in a Soxhlet extractor and heated under reflux during extraction. The product was then dried to obtain a modified nitrile rubber.

[0033] (3) 700 g of polyethylene resin, 300 g of modified nitrile rubber, 80 g of TDI-modified montmorillonite (prepared in Example 1), and 3 g of antioxidant 168 were added to a twin-screw extruder. The melt extrusion temperature was 185° C., the screw speed was 100 r / min, and extrusion granulation and injection molding were performed to obtain modified polyethylene plastic.

[0034] Comparative Example 1

[0035] (1) 900 g of polyethylene resin and 3 g of antioxidant 168 were added into a twin-screw extruder, the melt extrusion temperature was 195° C., the screw speed was 50 r / min, extrusion granulation was performed, and injection molding was performed to obtain modified polyethylene plastic.

[0036] Comparative Example 2

[0037] (1) 900 g of polyethylene resin, 100 g of modified nitrile rubber (prepared in Example 1), and 3 g of antioxidant 168 were added to a twin-screw extruder at a melt extrusion temperature of 195° C. and a screw speed of 50 r / min. The extrusion was granulated and injection molded to obtain a modified polyethylene plastic.

[0038] Comparative Example 3

[0039] (1) 900 g of polyethylene resin, 100 g of modified nitrile rubber (prepared in Example 1), 10 g of montmorillonite, and 3 g of antioxidant 168 were added to a twin-screw extruder. The melt extrusion temperature was 195° C., the screw speed was 50 r / min, and extrusion granulation and injection molding were performed to obtain modified polyethylene plastic.

[0040] Comparative Example 4

[0041] (1) 900 g of polyethylene resin, 10 g of TDI-modified montmorillonite (prepared in Example 1), and 3 g of antioxidant 168 were added to a twin-screw extruder at a melt extrusion temperature of 195° C. and a screw speed of 50 r / min. The mixture was extruded into granules and injection molded to obtain a modified polyethylene plastic.

[0042] Comparative Example 5

[0043] (1) 900 g of polyethylene resin, 100 g of nitrile rubber, 10 g of TDI-modified montmorillonite (prepared in Example 1), and 3 g of antioxidant 168 were added to a twin-screw extruder at a melt extrusion temperature of 195° C. and a screw speed of 50 r / min. The extrusion was granulated and injection molded to obtain a modified polyethylene plastic.

[0044] The modified polyethylene plastic is injected into a test specimen by an injection molding machine at an injection molding temperature of 210°C.

[0045] The tensile properties are tested according to GB / T 1040.1-2018. The impact strength is tested according to GB / T 1843-2008. The test results are shown in Table 1.

[0046] Table 1: Performance Test

[0047]

[0048] It can be seen from Table 1 that the polyethylene plastic of Comparative Example 1 has low tensile strength, elongation at break, tensile elastic modulus and impact strength, and poor mechanical properties.

[0049] Compared with Comparative Example 1, Comparative Example 2 adds modified nitrile rubber, which contains a long carbon alkyl chain and has an alkyl chain structure similar to that of polyethylene, so that the nitrile rubber and the polyethylene resin have better compatibility, and a composite plastic with better performance can be obtained, and the mechanical properties such as tensile strength and impact strength are significantly improved. However, it does not add TDI modified montmorillonite, and the mechanical properties are lower than those of Example 1.

[0050] Compared with Example 1, the montmorillonite added in Comparative Example 3 has not been modified with toluene-2,4-diisocyanate, and has poor compatibility with polyethylene resin. Montmorillonite does not contain isocyanate groups and cannot react with hydroxyl groups in modified nitrile rubber. Its compatibility and interfacial bonding strength with nitrile rubber are also poor, resulting in poor dispersibility of montmorillonite, poor reinforcement effect, and mechanical properties such as tensile strength being lower than those in Example 1.

[0051] Comparative Example 4 adds TDI-modified montmorillonite, which has good compatibility with polyethylene resin and excellent dispersibility. The mechanical properties of the material are higher than those of Comparative Example 1. However, no modified nitrile rubber is added, and the mechanical properties such as tensile strength are lower than those of the embodiment.

[0052] The nitrile rubber added in Comparative Example 5 has not been modified, does not contain long alkyl chains, has low compatibility with polyethylene resin, and does not contain hydroxyl groups, and cannot react with the isocyanate groups of TDI-modified montmorillonite. The compatibility between the nitrile rubber and montmorillonite is also lower than that in Example 1, resulting in the tensile strength and other mechanical properties of the material being lower than those in Example 1.

[0053] This specific embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed. However, as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

Claims

1. A modified polyethylene plastic, characterized in that: The modified polyethylene plastic comprises 70-90 parts by weight of polyethylene resin, 10-30 parts by weight of modified nitrile rubber, 1-8 parts by weight of TDI modified montmorillonite, and 0.3-0.5 parts by weight of antioxidant; The preparation method of the modified nitrile rubber is: Adding nitrile rubber, acrylate modifier and dibenzoyl peroxide into a torque rheometer for melt grafting, extracting the product with acetone in a Soxhlet extractor after cooling, and drying to obtain modified nitrile rubber; The general structural formula of the acrylate modifier is as follows: n is any integer between 14 and 18.

2. The modified polyethylene plastic according to claim 1, characterized in that The mass of the acrylate modifier and dibenzoyl peroxide are 5-20% and 0.15-0.64% of the mass of the nitrile rubber respectively.

3. The modified polyethylene plastic according to claim 1, characterized in that: The temperature during the melt grafting is 170-175° C. and the time is 10-30 minutes.

4. The modified polyethylene plastic according to claim 2, characterized in that: The preparation method of the acrylate modifier is as follows: adding a cosolvent, glycidyl methacrylate and an alkylamine into a solvent, heating to 40-50° C., stirring for reaction for 4-6 hours, distilling under reduced pressure, washing and recrystallizing to obtain the acrylate modifier.

5. The modified polyethylene plastic according to claim 4, characterized in that: The volume ratio of the solvent to the co-solvent is 1:(0.3-0.5); the solvent is tetrahydrofuran or ethanol, and the co-solvent is dichloromethane or chloroform.

6. The modified polyethylene plastic according to claim 4, characterized in that: The molar amount of the alkylamine is 100-110% of the molar amount of glycidyl methacrylate.

7. The modified polyethylene plastic according to claim 6, characterized in that: The general structural formula of the alkylamine is H2N-C n H 2n+1 , n is any integer between 14 and 18.

8. The modified polyethylene plastic according to claim 1, characterized in that: The preparation method of the TDI modified montmorillonite comprises the following steps: adding dry montmorillonite and toluene-2,4-diisocyanate into toluene, heating and stirring for reaction, filtering, washing, and drying to obtain the TDI modified montmorillonite.

9. A method for preparing the modified polyethylene plastic according to any one of claims 1 to 8, characterized in that: The preparation method comprises the following steps: adding polyethylene resin, modified nitrile rubber, TDI modified montmorillonite and antioxidant into a twin-screw extruder, with the melt extrusion temperature being 185-195°C, the screw speed being 50-100r / min, extruding granulation and injection molding to obtain modified polyethylene plastic.

10. Use of the modified polyethylene plastic obtained by the preparation method as claimed in claim 9 in the preparation of high-strength trash cans.

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