Regenerated plastic for film blowing and preparation method thereof

Abstract

The invention discloses a reprocessed plastic for film blowing and a preparation method thereof, and belongs to the technical field of reprocessed plastics, the reprocessed plastic for film blowing is prepared by taking a modified high-density polyethylene reprocessed material, a low-density polyethylene reprocessed material, an antioxidant and acrylic acid grafted rice hull powder as raw materials, mixing the raw materials, and performing melt extrusion, granulation and drying to obtain the reprocessed plastic. According to the invention, the initiator and the short-chain grafted monomer are firstly attached to the surface of the high-density polyethylene reclaimed material to form the modified high-density polyethylene reclaimed material, and the main chain of the modified high-density polyethylene reclaimed material is grafted with the short-chain branched chain in the melt extrusion process, so that the fluidity of the modified high-density polyethylene reclaimed material is improved, and the melt index of the reclaimed plastic meets the requirements of a film blowing process. The acrylic acid grafted rice hull powder is added as a biodegradation promoting material, and acrylic acid is grafted on the surface of the rice hull powder, so that the rice hull powder has good compatibility with the modified high-density polyethylene in the regenerated plastic, and the biodegradability of the regenerated plastic is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of recycled plastics, and particularly relates to recycled plastics for film blowing and a preparation method thereof. Background Art

[0002] Recycling plastic waste has always been a significant challenge for the recycling industry. With the rapid development of the plastics industry, the recycling of waste plastics has become an effective means of energy conservation, emission reduction, and environmental protection, garnering significant attention both domestically and internationally. Recycled plastics are primarily plastic pellets obtained by processing waste plastics through physical or chemical methods such as pretreatment (screening, sorting, and cleaning), melt extrusion granulation, and modification.

[0003] There are many types of recycled plastics, including recycled polyethylene (PE), recycled polypropylene (PP), recycled ABS and recycled polyvinyl chloride (PVC). Among them, recycled polyethylene has been widely used in many industries due to its diverse uses and environmental protection properties.

[0004] Recycled polyethylene is made into thin films through the blown film process and can be used to make agricultural mulch, garbage bags, and other non-food-grade plastic bags. The melt index (MI) of the resin particles used for blown film cannot be too high. If the MI is too high, the viscosity of the molten resin will be too low, the processing range will be narrow, the processing conditions will be difficult to control, the film-forming properties of the resin will be poor, and it will not be easy to process into films. The smaller the MI value, the greater the viscosity and average molecular weight of the raw material, the worse the fluidity and processing performance will be. Therefore, blown polyethylene film generally uses polyethylene raw materials with a melt index (MI) between 2 and 6 g / 10 min. However, due to different sources, the melt index of recycled polyethylene materials varies significantly. The melt index of low-density polyethylene recycled materials is relatively high, while the melt index of high-density polyethylene recycled materials is relatively low. Directly blending two recycled polyethylene materials of different densities may cause uneven distribution of other additives due to the difference in fluidity between the two materials, thus affecting product quality and making it difficult to achieve ideal processing results. Summary of the Invention

[0005] The purpose of the present invention is to provide a recycled plastic for film blowing and a preparation method thereof, and to improve the film blowing processing performance of the recycled polyethylene plastic by improving the formula and preparation method thereof.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] The present invention provides a recycled plastic for blown film, which comprises the following raw materials in parts by mass:

[0008] 20-40 parts of modified high-density polyethylene recycled material, 60-80 parts of low-density polyethylene recycled material, 1-3 parts of antioxidant, and 2.0-4.8 parts of acrylic acid grafted rice husk powder.

[0009] Furthermore, the preparation steps of the modified high-density polyethylene recycled material are as follows:

[0010] The initiator and short chain grafting monomer are dissolved in acetone, and high-density polyethylene (HDPE) recycled material is added and mixed evenly. The initiator accounts for 1-3% of the mass of the high-density polyethylene recycled material, and the short chain grafting monomer accounts for 4-6% of the mass of the high-density polyethylene recycled material. After filtering, the acetone is completely volatilized to obtain the modified high-density recycled material.

[0011] Under the action of initiators and short-chain grafting monomers, high-density polyethylene recycled material can be grafted with short branches on the main chain during the melting process. Unlike the chain entanglement effect of long-chain branches, the presence of short branches can increase the distance between molecular chains, reduce entanglement points, thereby reducing the viscosity of the molecular chain and improving the fluidity of HDPE. When the concentration of short-chain grafting monomers is too low, the collision probability between the surface of the high-density polyethylene recycled material and the short-chain grafting monomers is low, and the grafting effect will be reduced. Increasing the concentration of short-chain grafting monomers can increase the collision probability of free radicals generated by the short-chain grafting monomers at high temperatures with high-density polyethylene molecules, thereby improving the grafting rate.

[0012] Furthermore, the initiator is one of benzoyl peroxide and dicumyl peroxide. Peroxide initiators are commonly used grafting initiators and can generate free radicals by decomposition to promote the occurrence of grafting reactions.

[0013] Furthermore, the short-chain grafting monomer is at least one of ethyl acrylate, methyl methacrylate, and ethyl methacrylate. Acrylate grafting monomers have high grafting efficiency and relatively short molecular chains. When grafted onto high-density polyethylene (HDPE), carbonyl groups attach to the polyethylene material, improving compatibility with the acrylic acid-grafted rice hulls and indirectly promoting the biodegradability of the HDPE.

[0014] Furthermore, the antioxidant is at least one of antioxidant 1010 and antioxidant 168.

[0015] Furthermore, the preparation steps of the acrylic acid grafted rice husk powder are as follows:

[0016] Methyl acrylate and rice husk powder are added to deionized water, the water bath temperature is controlled at 60-70°C, potassium persulfate is added under nitrogen protection, the mass ratio of methyl acrylate, potassium persulfate and rice husk powder is 1-2:1:5, and the reaction is stirred for 3-4 hours. The reaction product is separated with acetone, and the acetone is recovered by distillation to obtain acrylic acid grafted rice husk powder.

[0017] Rice husk is a natural material with abundant sources and low cost. It is rich in cellulose and lignin. During the grafting process, the phenolic hydroxyl groups in the rice husk react with acrylic monomers to form new COC bonds. Acrylic acid grafted rice husk powder can improve the dispersibility of rice husk in recycled plastics, enhance the biodegradability of recycled plastics, facilitate subsequent processing, and increase the utilization value of rice husk powder.

[0018] Furthermore, the ratio of the modified high-density polyethylene recycled material to the low-density polyethylene recycled material is (1:1)-(7:3). A high ratio of the modified high-density polyethylene recycled material results in better mechanical properties, while a high ratio of the low-density polyethylene recycled material results in better fluidity. By adjusting the ratio of the modified high-density polyethylene recycled material to the low-density polyethylene recycled material, a balance between mechanical properties and processing performance can be achieved.

[0019] Furthermore, the acrylic acid grafted rice husk powder accounts for 5-12% of the mass of the modified high-density polyethylene recycled material.

[0020] The present invention also provides a method for preparing the recycled plastic for film blowing as described above, comprising the following steps:

[0021] Step 1: Add the raw materials into a high-speed mixer according to the proportion, and stir and mix to obtain a mixture;

[0022] Step 2: Put the mixed material into a screw machine for melt extrusion, granulation and drying to obtain recycled plastic.

[0023] Furthermore, the melt extrusion temperature is 190-230° C., and the screw speed is 200-250 r / min.

[0024] Beneficial effects of the present invention:

[0025] (1) The present invention first attaches an initiator and a grafting monomer to the surface of a high-density polyethylene recycled material to form a modified high-density polyethylene recycled material, and then mixes the modified high-density polyethylene recycled material, a low-density polyethylene recycled material, and other raw materials, and then melts the mixture. By mixing, a spatial distance is created between the high-density polyethylene recycled materials, which can reduce the probability of self-crosslinking of the main chain of the high-density polyethylene recycled material at high temperature, increase the probability of grafting short branches on the main chain, improve its fluidity, and enable the high-density polyethylene recycled material and the low-density polyethylene recycled material to be uniformly mixed with other raw materials during the melt blending process, thereby improving the comprehensive performance of the recycled plastic.

[0026] (2) The present invention adds acrylic acid grafted rice husk powder to the recycled plastic raw material as a biodegradable material. Acrylic acid is grafted on the surface of the rice husk powder, so that it has good compatibility with modified high-density polyethylene in the recycled plastic, can improve the biodegradability of the recycled plastic, and has environmentally friendly characteristics.

[0027] (3) The present invention adjusts the ratio of high-density polyethylene recycled material to low-density polyethylene recycled material to control the melt index of the recycled plastic to meet the requirements of the film blowing process, so that the recycled plastic has excellent processing performance. DETAILED DESCRIPTION

[0028] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0029] Example 1

[0030] Preparation of modified high-density polyethylene recycled materials:

[0031] 10 g of dicumyl peroxide and 40 g of methyl methacrylate were added to the reactor, and then 1 L of acetone was added. After stirring until dissolved, 1000 g of high-density polyethylene recycled material was added and continued to stir until the mixture was uniform. The material obtained after filtration was purged with nitrogen to volatilize and remove the acetone to obtain a modified high-density recycled material.

[0032] Preparation of acrylic acid grafted rice husk powder:

[0033] Add 500 mL of deionized water, 2 g of methyl acrylate and 10 g of rice husk powder (particle size 100-200 nm) to a three-necked flask, control the water bath temperature to 60°C, add 2 g of potassium persulfate under nitrogen protection, stir and react for 4 hours, separate the reaction product with acetone, and distill and recover the acetone to obtain acrylic acid-grafted rice husk powder.

[0034] Preparation of recycled plastics:

[0035] Step 1: Add the raw materials into a high-speed blender according to the proportion, and stir and mix to obtain a mixture. The specific proportion of the raw materials is as follows:

[0036] Calculated by mass, the ingredients include 40 parts of modified high-density polyethylene recycled material, 60 parts of low-density polyethylene recycled material, 10101 parts of antioxidant, and 2 parts of acrylic acid grafted rice husk powder.

[0037] Step 2: Put the mixed material into a screw machine for melt extrusion, control the melt extrusion temperature to 190° C., and the screw speed to 200 r / min, and then granulate and dry in sequence to obtain recycled plastic.

[0038] Example 2

[0039] The only difference from Example 1 is that the amount of methyl methacrylate in the modified high-density polyethylene recycled material is adjusted from 40 g to 50 g. The specific steps are as follows:

[0040] Preparation of modified high-density polyethylene recycled materials:

[0041] 10 g of dicumyl peroxide and 50 g of methyl methacrylate were added to the reactor, and then 1 L of acetone was added. After stirring until dissolved, 1000 g of high-density polyethylene recycled material was added and continued to stir until the mixture was uniform. The material obtained after filtration was purged with nitrogen to volatilize and remove the acetone to obtain a modified high-density recycled material.

[0042] Preparation of acrylic acid grafted rice husk powder:

[0043] Add 500 mL of deionized water, 2 g of methyl acrylate and 10 g of rice husk powder (particle size 100-200 nm) to a three-necked flask, control the water bath temperature to 60°C, add 2 g of potassium persulfate under nitrogen protection, stir and react for 4 hours, separate the reaction product with acetone, and distill and recover the acetone to obtain acrylic acid-grafted rice husk powder.

[0044] Preparation of recycled plastics:

[0045] Step 1: Add the raw materials into a high-speed blender according to the proportion, and stir and mix to obtain a mixture. The specific proportion of the raw materials is as follows:

[0046] Calculated by mass, the ingredients include 40 parts of modified high-density polyethylene recycled material, 60 parts of low-density polyethylene recycled material, 10101 parts of antioxidant, and 2 parts of acrylic acid grafted rice husk powder.

[0047] Step 2: Put the mixed material into a screw machine for melt extrusion, control the melt extrusion temperature to 190° C., and the screw speed to 200 r / min, and then granulate and dry in sequence to obtain recycled plastic.

[0048] Example 3

[0049] The only difference from Example 1 is that the amount of methyl methacrylate in the modified high-density polyethylene recycled material is adjusted from 40 g to 60 g. The specific steps are as follows:

[0050] Preparation of modified high-density polyethylene recycled materials:

[0051] 10 g of dicumyl peroxide and 60 g of methyl methacrylate were added to the reactor, and then 1 L of acetone was added. After stirring until dissolved, 1000 g of high-density polyethylene recycled material was added and continued to stir until the mixture was uniform. The material obtained after filtration was purged with nitrogen to volatilize and remove the acetone to obtain a modified high-density recycled material.

[0052] Preparation of acrylic acid grafted rice husk powder:

[0053] Add 500 mL of deionized water, 2 g of methyl acrylate and 10 g of rice husk powder (particle size 100-200 nm) to a three-necked flask, control the water bath temperature to 60°C, add 2 g of potassium persulfate under nitrogen protection, stir and react for 4 hours, separate the reaction product with acetone, and distill and recover the acetone to obtain acrylic acid-grafted rice husk powder.

[0054] Preparation of recycled plastics:

[0055] Step 1: Add the raw materials into a high-speed blender according to the proportion, and stir and mix to obtain a mixture. The specific proportion of the raw materials is as follows:

[0056] Calculated by mass, the ingredients include 40 parts of modified high-density polyethylene recycled material, 60 parts of low-density polyethylene recycled material, 10101 parts of antioxidant, and 2 parts of acrylic acid grafted rice husk powder.

[0057] Step 2: Put the mixed material into a screw machine for melt extrusion, control the melt extrusion temperature to 190° C., and the screw speed to 200 r / min, and then granulate and dry in sequence to obtain recycled plastic.

[0058] Example 4

[0059] The only difference from Example 2 is that the modified high-density polyethylene recycled material in the raw materials for preparing the recycled plastic is adjusted to 30 parts, and the low-density polyethylene recycled material is adjusted to 70 parts. The specific steps are as follows:

[0060] Preparation of modified high-density polyethylene recycled materials:

[0061] 10 g of dicumyl peroxide and 60 g of methyl methacrylate were added to the reactor, and then 1 L of acetone was added. After stirring until dissolved, 1000 g of high-density polyethylene recycled material was added and continued to stir until the mixture was uniform. The material obtained after filtration was purged with nitrogen to volatilize and remove the acetone to obtain a modified high-density recycled material.

[0062] Preparation of acrylic acid grafted rice husk powder:

[0063] Add 500 mL of deionized water, 2 g of methyl acrylate and 10 g of rice husk powder (particle size 100-200 nm) to a three-necked flask, control the water bath temperature to 60°C, add 2 g of potassium persulfate under nitrogen protection, stir and react for 4 hours, separate the reaction product with acetone, and distill and recover the acetone to obtain acrylic acid-grafted rice husk powder.

[0064] Preparation of recycled plastics:

[0065] Step 1: Add the raw materials into a high-speed blender according to the proportion, and stir and mix to obtain a mixture. The specific proportion of the raw materials is as follows:

[0066] Calculated by mass, the ingredients include 30 parts of modified high-density polyethylene recycled material, 70 parts of low-density polyethylene recycled material, 10101 parts of antioxidant, and 2 parts of acrylic acid grafted rice husk powder.

[0067] Step 2: Put the mixed material into a screw machine for melt extrusion, control the melt extrusion temperature to 210° C., and the screw speed to 230 r / min, and then granulate and dry in sequence to obtain recycled plastic.

[0068] Example 5

[0069] The only difference from Example 2 is that the modified high-density polyethylene recycled material in the raw materials for preparing the recycled plastic is adjusted to 20 parts, and the low-density polyethylene recycled material is adjusted to 80 parts. The specific steps are as follows:

[0070] Preparation of modified high-density polyethylene recycled materials:

[0071] 10 g of dicumyl peroxide and 60 g of methyl methacrylate were added to the reactor, and then 1 L of acetone was added. After stirring until dissolved, 1000 g of high-density polyethylene recycled material was added and continued to stir until the mixture was uniform. The material obtained after filtration was purged with nitrogen to volatilize and remove the acetone to obtain a modified high-density recycled material.

[0072] Preparation of acrylic acid grafted rice husk powder:

[0073] Add 500 mL of deionized water, 2 g of methyl acrylate and 10 g of rice husk powder (particle size 100-200 nm) to a three-necked flask, control the water bath temperature to 60°C, add 2 g of potassium persulfate under nitrogen protection, stir and react for 4 hours, separate the reaction product with acetone, and distill and recover the acetone to obtain acrylic acid-grafted rice husk powder.

[0074] Preparation of recycled plastics:

[0075] Step 1: Add the raw materials into a high-speed blender according to the proportion, and stir and mix to obtain a mixture. The specific proportion of the raw materials is as follows:

[0076] Calculated by mass, the ingredients include 20 parts of modified high-density polyethylene recycled material, 80 parts of low-density polyethylene recycled material, 10101 parts of antioxidant, and 2 parts of acrylic acid grafted rice husk powder.

[0077] Step 2: Put the mixed material into a screw machine for melt extrusion, control the melt extrusion temperature to 230°C and the screw speed to 250r / min, and then granulate and dry in sequence to obtain recycled plastic.

[0078] Example 6

[0079] The only difference from Example 4 is that the amount of methyl acrylate used to prepare the acrylic acid-grafted rice husk powder is adjusted to 3 g. Other conditions and steps are the same as those in Example 1. The specific steps are as follows:

[0080] Preparation of modified high-density polyethylene recycled materials:

[0081] 10 g of dicumyl peroxide and 60 g of methyl methacrylate were added to the reactor, and then 1 L of acetone was added. After stirring until dissolved, 1000 g of high-density polyethylene recycled material was added and continued to stir until the mixture was uniform. The material obtained after filtration was purged with nitrogen to volatilize and remove the acetone to obtain a modified high-density recycled material.

[0082] Preparation of acrylic acid grafted rice husk powder:

[0083] Add 500 mL of deionized water, 3 g of methyl acrylate and 10 g of rice husk powder (particle size 100-200 nm) to a three-necked flask, control the water bath temperature to 60°C, add 2 g of potassium persulfate under nitrogen protection, stir and react for 4 hours, separate the reaction product with acetone, and distill and recover the acetone to obtain acrylic acid-grafted rice husk powder.

[0084] Preparation of recycled plastics:

[0085] Step 1: Add the raw materials into a high-speed blender according to the proportion, and stir and mix to obtain a mixture. The specific proportion of the raw materials is as follows:

[0086] Calculated by mass, the ingredients include 30 parts of modified high-density polyethylene recycled material, 70 parts of low-density polyethylene recycled material, 10101 parts of antioxidant, and 2 parts of acrylic acid grafted rice husk powder.

[0087] Step 2: Put the mixed material into a screw machine for melt extrusion, control the melt extrusion temperature to 210° C., and the screw speed to 230 r / min, and then granulate and dry in sequence to obtain recycled plastic.

[0088] Example 7

[0089] The only difference from Example 4 is that the amount of methyl acrylate used to prepare the acrylic acid-grafted rice husk powder is adjusted to 4 g. Other conditions and steps are the same as those in Example 1. The specific steps are as follows:

[0090] Preparation of modified high-density polyethylene recycled materials:

[0091] 10 g of dicumyl peroxide and 60 g of methyl methacrylate were added to the reactor, and then 1 L of acetone was added. After stirring until dissolved, 1000 g of high-density polyethylene recycled material was added and continued to stir until the mixture was uniform. The material obtained after filtration was purged with nitrogen to volatilize and remove the acetone to obtain a modified high-density recycled material.

[0092] Preparation of acrylic acid grafted rice husk powder:

[0093] Add 500 mL of deionized water, 4 g of methyl acrylate and 10 g of rice husk powder (particle size 100-200 nm) to a three-necked flask, control the water bath temperature to 60°C, add 2 g of potassium persulfate under nitrogen protection, stir and react for 4 hours, separate the reaction product with acetone, and distill to recover the acetone to obtain acrylic acid-grafted rice husk powder.

[0094] Preparation of recycled plastics:

[0095] Step 1: Add the raw materials into a high-speed blender according to the proportion, and stir and mix to obtain a mixture. The specific proportion of the raw materials is as follows:

[0096] Calculated by mass, the ingredients include 30 parts of modified high-density polyethylene recycled material, 70 parts of low-density polyethylene recycled material, 10101 parts of antioxidant, and 2 parts of acrylic acid grafted rice husk powder.

[0097] Step 2: Put the mixed material into a screw machine for melt extrusion, control the melt extrusion temperature to 210° C., and the screw speed to 230 r / min, and then granulate and dry in sequence to obtain recycled plastic.

[0098] Example 8

[0099] The only difference from Example 6 is that the amount of acrylic acid grafted rice husk powder in the raw material for preparing the recycled plastic is adjusted to 3 parts. The specific steps are as follows:

[0100] Preparation of modified high-density polyethylene recycled materials:

[0101] 10 g of dicumyl peroxide and 60 g of methyl methacrylate were added to the reactor, and then 1 L of acetone was added. After stirring until dissolved, 1000 g of high-density polyethylene recycled material was added and continued to stir until the mixture was uniform. The material obtained after filtration was purged with nitrogen to volatilize and remove the acetone to obtain a modified high-density recycled material.

[0102] Preparation of acrylic acid grafted rice husk powder:

[0103] Add 500 mL of deionized water, 3 g of methyl acrylate and 10 g of rice husk powder (particle size 100-200 nm) to a three-necked flask, control the water bath temperature to 60°C, add 2 g of potassium persulfate under nitrogen protection, stir and react for 4 hours, separate the reaction product with acetone, and distill and recover the acetone to obtain acrylic acid-grafted rice husk powder.

[0104] Preparation of recycled plastics:

[0105] Step 1: Add the raw materials into a high-speed blender according to the proportion, and stir and mix to obtain a mixture. The specific proportion of the raw materials is as follows:

[0106] Calculated by mass, the ingredients include 30 parts of modified high-density polyethylene recycled material, 70 parts of low-density polyethylene recycled material, 10101 parts of antioxidant, and 3 parts of acrylic acid grafted rice husk powder.

[0107] Step 2: Put the mixed material into a screw machine for melt extrusion, control the melt extrusion temperature to 210° C., and the screw speed to 230 r / min, and then granulate and dry in sequence to obtain recycled plastic.

[0108] Example 9

[0109] The only difference from Example 6 is that the amount of acrylic acid grafted rice husk powder in the raw material for preparing the recycled plastic is adjusted to 3.6 parts. The specific steps are as follows:

[0110] Preparation of modified high-density polyethylene recycled materials:

[0111] 10 g of dicumyl peroxide and 60 g of methyl methacrylate were added to the reactor, and then 1 L of acetone was added. After stirring until dissolved, 1000 g of high-density polyethylene recycled material was added and continued to stir until the mixture was uniform. The material obtained after filtration was purged with nitrogen to volatilize and remove the acetone to obtain a modified high-density recycled material.

[0112] Preparation of acrylic acid grafted rice husk powder:

[0113] Add 500 mL of deionized water, 3 g of methyl acrylate and 10 g of rice husk powder (particle size 100-200 nm) to a three-necked flask, control the water bath temperature to 60°C, add 2 g of potassium persulfate under nitrogen protection, stir and react for 4 hours, separate the reaction product with acetone, and distill and recover the acetone to obtain acrylic acid-grafted rice husk powder.

[0114] Preparation of recycled plastics:

[0115] Step 1: Add the raw materials into a high-speed blender according to the proportion, and stir and mix to obtain a mixture. The specific proportion of the raw materials is as follows:

[0116] Calculated by mass, the ingredients include 30 parts of modified high-density polyethylene recycled material, 70 parts of low-density polyethylene recycled material, 10101 parts of antioxidant, and 3.6 parts of acrylic acid grafted rice husk powder.

[0117] Step 2: Put the mixed material into a screw machine for melt extrusion, control the melt extrusion temperature to 210° C., and the screw speed to 230 r / min, and then granulate and dry in sequence to obtain recycled plastic.

[0118] Comparative Example 1

[0119] Compared with Example 1, the difference of this comparative example is that high-density polyethylene recycled material is used to replace modified high-density polyethylene recycled material to prepare recycled plastic. The specific steps are as follows:

[0120] Preparation of acrylic acid grafted rice husk powder:

[0121] Add 500 mL of deionized water, 2 g of methyl acrylate and 10 g of rice husk powder (particle size 100-200 nm) to a three-necked flask, control the water bath temperature to 60°C, add 2 g of potassium persulfate under nitrogen protection, stir and react for 4 hours, separate the reaction product with acetone, and distill and recover the acetone to obtain acrylic acid-grafted rice husk powder.

[0122] Preparation of recycled plastics:

[0123] Step 1: Add the raw materials into a high-speed blender according to the proportion, and stir and mix to obtain a mixture. The specific proportion of the raw materials is as follows:

[0124] Calculated by mass, 40 parts of high-density polyethylene recycled material, 60 parts of low-density polyethylene recycled material, 10101 parts of antioxidant, and 2 parts of acrylic acid grafted rice husk powder.

[0125] Step 2: Put the mixed material into a screw machine for melt extrusion, control the melt extrusion temperature to 190° C., and the screw speed to 200 r / min, and then granulate and dry in sequence to obtain recycled plastic.

[0126] Comparative Example 2

[0127] Compared with Example 1, the difference of this comparative example is that the modified high-density polyethylene recycled material is first subjected to melt reaction modification, and then the recycled plastic is prepared with other raw materials. The specific steps are as follows:

[0128] Preparation of modified high-density polyethylene recycled materials:

[0129] 10 g of dicumyl peroxide and 40 g of methyl methacrylate were added to the reactor, and then 1 L of acetone was added. After stirring until dissolved, 1000 g of high-density polyethylene recycled material was added and continued to stir until the mixture was uniform. The material obtained after filtration was purged with nitrogen to volatilize and remove the acetone to obtain a modified high-density recycled material.

[0130] Preparation of acrylic acid grafted rice husk powder:

[0131] Add 500 mL of deionized water, 2 g of methyl acrylate and 10 g of rice husk powder (particle size 100-200 nm) to a three-necked flask, control the water bath temperature to 60°C, add 2 g of potassium persulfate under nitrogen protection, stir and react for 4 hours, separate the reaction product with acetone, and distill and recover the acetone to obtain acrylic acid-grafted rice husk powder.

[0132] Preparation of recycled plastics:

[0133] Step 1: Add the modified high-density polyethylene recycled material into a screw machine, melt-extrude, granulate, and dry to obtain modified high-density polyethylene recycled material particles. The melt extrusion temperature is 190° C. and the screw speed is 200 r / min.

[0134] Step 2: Add the raw materials into a high-speed blender according to the proportion, and stir and mix to obtain a mixture. The specific proportion of the raw materials is as follows:

[0135] Calculated by mass, the ingredients include 40 parts of modified high-density polyethylene recycled material particles, 60 parts of low-density polyethylene recycled material, 10101 parts of antioxidant, and 2 parts of acrylic acid grafted rice husk powder.

[0136] Step 3: Put the mixed material into a screw machine for melt extrusion, control the melt extrusion temperature to 190°C and the screw speed to 200r / min, and then granulate and dry in sequence to obtain recycled plastic.

[0137] Comparative Example 3

[0138] Compared with Example 1, the only difference in this comparative example is that rice husk powder is used instead of acrylic acid grafted rice husk powder to prepare recycled plastic. The specific steps are as follows:

[0139] Preparation of modified high-density polyethylene recycled materials:

[0140] 10 g of dicumyl peroxide and 40 g of methyl methacrylate were added to the reactor, and then 1 L of acetone was added. After stirring until dissolved, 1000 g of high-density polyethylene recycled material was added and continued to stir until the mixture was uniform. The material obtained after filtration was purged with nitrogen to volatilize and remove the acetone to obtain a modified high-density recycled material.

[0141] Preparation of recycled plastics:

[0142] Step 1: Add the raw materials into a high-speed blender according to the proportion, and stir and mix to obtain a mixture. The specific proportion of the raw materials is as follows:

[0143] Calculated by mass, 40 parts of modified high-density polyethylene recycled material, 60 parts of low-density polyethylene recycled material, 10101 parts of antioxidant, and 2 parts of rice husk powder.

[0144] Step 2: Put the mixed material into a screw machine for melt extrusion, control the melt extrusion temperature to 190° C., and the screw speed to 200 r / min, and then granulate and dry in sequence to obtain recycled plastic.

[0145] The high-density polyethylene recycled material and low-density polyethylene recycled material in the examples and comparative examples are conventional commercially available products.

[0146] The performance tests were performed on the recycled plastics prepared in Examples 1 to 9 and Comparative Examples 1 to 3. The results are shown in Table 1.

[0147] Biodegradation performance test of recycled plastics: First weigh the recycled plastic, then bury it in the soil for 200 days, take it out, wash it, dry it, and weigh it, and calculate the weight loss rate before and after burial.

[0148] Table 1

[0149] project Melt index g / 10min Biodegradation weight loss rate by soil burial method % Example 1 3.5 18.3 Example 2 4.6 18.5 Example 3 4.4 18.9 Example 4 5.2 20.4 Example 5 5.8 20.6 Example 6 5.3 20.9 Example 7 5.3 21.0 Example 8 5.3 21.4 Example 9 5.3 21.7 Comparative Example 1 1.3 13.2 Comparative Example 2 1.8 14.1 Comparative Example 3 3.2 12.4

[0150] As can be seen from Table 1, in Examples 1 to 3, as the amount of methyl methacrylate in the modified high-density polyethylene recycled material increases, the melt index of the prepared recycled material changes significantly. In Example 2, the melt index is the largest and the flowability is the best. In Examples 4 and 5, based on Example 2, the ratio of modified high-density polyethylene recycled material to low-density polyethylene recycled material in the raw materials of the recycled plastic is adjusted. The melt index data show that when the mass ratio of modified high-density polyethylene recycled material to low-density polyethylene recycled material is 2:8, the flowability of the recycled plastic is the best. In Examples 6 and 7, the grafting rate is increased by increasing the amount of methyl acrylate when preparing acrylic acid grafted rice husk powder. As the grafting rate increases, the compatibility of acrylic acid grafted rice husk powder in the recycled plastic is enhanced, and the biodegradability of the recycled plastic is improved. In Comparative Example 1, under the condition that the high-density polyethylene recycled material is not modified, the prepared recycled plastic has a small melt index, high melt viscosity, poor fluidity, and is not conducive to blown film processing. In Comparative Example 2, the modified high-density polyethylene recycled material is first subjected to melt reaction modification, and then mixed and melt granulated to prepare the recycled plastic. When the melt reaction modification is first performed, since the high-density polyethylenes are in close contact with each other and the concentration is high, under the action of the initiator, part of the high-density polyethylene main chain will undergo self-cross-linking, resulting in enhanced intermolecular forces, increased viscosity, and poor fluidity; in Comparative Example 3, the rice husk powder is not grafted and modified. At this time, the compatibility of rice husk powder with polyethylene material is poor, and the biodegradability of the recycled plastic is not as good as that of the embodiment. In addition, due to the uneven dispersion of rice husk powder, the film may be blown apart during blown film molding, and film formation cannot be achieved.

[0151] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0152] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A recycled plastic for blown film, characterized in that: Calculated by mass, it includes the following raw materials: 20-40 parts of modified high-density polyethylene recycled material, 60-80 parts of low-density polyethylene recycled material, 1-3 parts of antioxidant, and 2.0-4.8 parts of acrylic acid grafted rice husk powder.

2. The recycled plastic for film blowing according to claim 1, characterized in that: The preparation steps of the modified high-density polyethylene recycled material are as follows: Dissolve the initiator and short chain grafting monomer in acetone, add high-density polyethylene recycled material and mix evenly. The initiator is 1-3% of the mass of the high-density polyethylene recycled material, and the short chain grafting monomer is 4-6% of the mass of the high-density polyethylene recycled material. After filtering, the acetone is completely volatilized to obtain the modified high-density recycled material.

3. The recycled plastic for film blowing according to claim 2, characterized in that: The initiator is one of benzoyl peroxide and dicumyl peroxide.

4. The recycled plastic for film blowing according to claim 2, characterized in that: The short chain grafting monomer is at least one of ethyl acrylate, methyl methacrylate and ethyl methacrylate.

5. The recycled plastic for film blowing according to claim 1, characterized in that: The antioxidant is at least one of the antioxidant 1010 and the antioxidant 168 .

6. The recycled plastic for film blowing according to claim 1, characterized in that: The preparation steps of the acrylic acid grafted rice husk powder are as follows: Methyl acrylate and rice husk powder are added to deionized water, the water bath temperature is controlled at 60-70°C, potassium persulfate is added under nitrogen protection, the mass ratio of methyl acrylate, potassium persulfate and rice husk powder is 1-2:1:5, and the reaction is stirred for 3-4 hours. The reaction product is separated with acetone, and the acetone is recovered by distillation to obtain acrylic acid grafted rice husk powder.

7. The recycled plastic for film blowing according to claim 1, characterized in that: The ratio of the modified high-density polyethylene recycled material to the low-density polyethylene recycled material is (1:1)-(7:3).

8. The recycled plastic for film blowing according to claim 1, characterized in that: The acrylic acid grafted rice husk powder accounts for 5-12% of the mass of the modified high-density polyethylene recycled material.

9. A method for preparing recycled plastic for blown film, characterized in that: The method for preparing the recycled plastic for blown film according to any one of claims 1 to 8 comprises the following steps: Step 1: Add the raw materials into a high-speed mixer according to the proportion, and stir and mix to obtain a mixture; Step 2: Put the mixed material into a screw machine for melt extrusion, granulation and drying to obtain recycled plastic.

10. The method for preparing recycled plastic for blown film according to claim 9, characterized in that: The melt extrusion temperature is 190-230° C., and the screw speed is 200-250 r / min.