Energy-saving polyethylene shrink film and preparation method thereof

Abstract

The invention belongs to the technical field of high polymer materials, and particularly relates to an energy-saving polyethylene shrink film and a preparation method thereof. In order to solve the problem that in the prior art, the heat shrinkage temperature of a polyethylene heat shrinkage film usually needs a high temperature, the energy-saving polyethylene heat shrinkage film comprises an outer layer, a middle layer and an inner layer which are connected in sequence, the outer layer comprises open smooth master batches, ultra-low density polyethylene and metallocene polyethylene, and the middle layer comprises ultra-low density polyethylene and metallocene polyethylene. The outer layer comprises polyethylene, the middle layer comprises ultra-low density polyethylene and metallocene polyethylene, the inner layer comprises open smooth master batches, ultra-low density polyethylene and metallocene polyethylene, and the interlayer ratio of the outer layer to the middle layer to the inner layer is (15-25%): (50-70%): (15-25%). A three-layer structure with a special interlayer ratio is adopted, each layer is made of a metallocene polyethylene material with ultra-low density, the molecular structure of the metallocene polyethylene material has a long branch chain, and other matching materials are added, so that the heat energy required by the shrinkage of the polyethylene heat shrinkage film is reduced, and the heat shrinkage temperature is reduced when the polyethylene heat shrinkage film is used.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to an energy-saving polyethylene shrink film and a preparation method thereof. Background Art

[0002] Commodity packaging is required to have the functions of protecting, preserving and beautifying commodities. With the development of the economy and the improvement of living standards, people's requirements for commodity packaging are getting higher and higher, and various novel packaging materials have emerged. Heat shrink film is a type of shrink film. Heat shrink film is used for the sale and transportation of various products, and its main function is to stabilize, cover and protect the products. The shrink film must have high puncture resistance, good shrinkage and certain shrinkage stress. During the shrinkage process, the film cannot produce holes. PE shrink film is an important type of heat shrink film, and its main component is polyethylene material. The heat shrinkage temperature of the polyethylene heat shrink film in the prior art usually requires a higher temperature to achieve the function of the inner shrink film to wrap the contents, resulting in a higher cost of use.

[0003] For example, a Chinese invention patent application discloses a highly transparent polyethylene heat shrinkable film and a preparation method thereof [application number: CN202310737763.3]. The invention application includes an inner layer, a middle layer and an outer layer, characterized in that the inner layer and the outer layer both include the following raw materials in parts by weight: 450-650 parts of LDPE, 100-350 parts of MLLDPE, 0-500 parts of HDPE, 0-5 parts of an opening agent and 4-8 parts of a PPA additive; the middle layer includes the following raw materials in parts by weight: 450-600 parts of LDPE, 100-200 parts of MLLDPE, 200-500 parts of LLDPE or HDPE, 8-12 parts of an opening agent and 4-8 parts of a PPA additive.

[0004] This invention application has the advantages of thin thickness, high transparency, good toughness, and strong barrier ability, but it still does not solve the above-mentioned problems. Summary of the invention

[0005] The object of the present invention is to provide an energy-saving polyethylene shrink film and a preparation method thereof in view of the above problems.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] An energy-saving polyethylene shrink film comprises an outer layer, an intermediate layer and an inner layer which are connected in sequence, wherein the outer layer comprises an open-type smooth masterbatch, an ultra-low density polyethylene and a metallocene polyethylene, the intermediate layer comprises an ultra-low density polyethylene and a metallocene polyethylene, the inner layer comprises an open-type smooth masterbatch, an ultra-low density polyethylene and a metallocene polyethylene, and the interlayer ratio of the outer layer, the intermediate layer and the inner layer is 15-25%: 50-70%: 15-25%.

[0008] In the above-mentioned energy-saving polyethylene shrink film, the outer layer is composed of open smooth masterbatch, ultra-low density polyethylene and metallocene polyethylene, the middle layer is composed of ultra-low density polyethylene and metallocene polyethylene, and the inner layer is composed of open smooth masterbatch, ultra-low density polyethylene and metallocene polyethylene.

[0009] In the above-mentioned energy-saving polyethylene shrink film, the open and smooth masterbatch is prepared by the following method: take 15-35 parts of anti-adhesion polymer, use ultrasonic grinding for 5-70 minutes, then add 65-85 parts of polyethylene powder resin, heat to 60°C and stir for 10-30 minutes, add a screw machine for extrusion and granulation, and obtain an open and smooth masterbatch.

[0010] In the above energy-saving polyethylene shrink film, the anti-adhesion polymer is a single component or a composite composition of an organosilicon polymer and a fatty acid amide polymer.

[0011] In the above energy-saving polyethylene shrink film, the anti-adhesion polymer includes one or more of silicone powder, stearyl stearic acid amide, stearyl erucic acid amide, behenic acid amide and ethylene bis stearic acid amide.

[0012] In the above-mentioned energy-saving polyethylene shrink film, the outer layer comprises 1-8 parts by weight of open smooth masterbatch, 40-50 parts by weight of ultra-low density polyethylene and 40-50 parts by weight of metallocene polyethylene.

[0013] In the above energy-saving polyethylene shrink film, the middle layer comprises 45-55 parts by weight of ultra-low density polyethylene and 45-55 parts by weight of metallocene polyethylene.

[0014] In the above energy-saving polyethylene shrink film, the inner layer comprises 1-8 parts by weight of open smooth masterbatch, 7-20 parts by weight of ultra-low density polyethylene and 65-75 parts by weight of metallocene polyethylene.

[0015] In the above energy-saving polyethylene shrink film, the total thickness of the energy-saving polyethylene shrink film is less than 50 μm, and the heat shrinkage temperature is less than 120° C.

[0016] A method for preparing the energy-saving polyethylene shrink film comprises the following steps:

[0017] Step 1: According to the components contained in each layer, the proportion of each component is measured respectively, and after being mixed evenly in a mixer, it is uniformly added to a three-stage co-extrusion extruder, heated to 160-185°C, stirred at a speed of 150-180rpm, and extruded into a three-layer co-extrusion die at a speed of 60rpm, and the extrusion temperature is 200-230°C;

[0018] Step 2: Raise the temperature of the three-layer co-extrusion die to 200-220°C, reduce the pressure to below 300Pa, react under this condition for 1-3min to obtain a polymer melt, and then extrude, blow, cool by ultra-fast cooling process, corona and trim the prepared polymer melt in sequence to obtain the energy-saving polyethylene shrink film. The ultra-fast cooling process is to use a low-temperature, high-volume, high-speed cooling device to quickly cool and solidify the viscous film to achieve high heat shrinkage performance.

[0019] Compared with the prior art, the advantages of the present invention are:

[0020] 1. The present invention adopts a three-layer structure with a special interlayer ratio. Each layer uses a metallocene polyethylene material with an ultra-low density, and its molecular structure has long branches. Other matching materials are added to reduce the heat energy required for the polyethylene heat shrinkable film to shrink, thereby reducing the heat shrinkage temperature during use.

[0021] 2. The materials used in the three-layer structure of the present invention are mainly polyethylene materials, and non-polyethylene materials account for less than 5% of the total materials, which belongs to the category of single material and is easy to be recycled in an environmentally friendly manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram of the structure of the invention;

[0023] In the figure: outer layer 1, middle layer 2, inner layer 3. DETAILED DESCRIPTION

[0024] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0025] Example 1

[0026] The present embodiment provides an energy-saving polyethylene shrink film and a preparation method thereof, the energy-saving polyethylene shrink film comprising an outer layer 1, an intermediate layer 2 and an inner layer 3 connected in sequence, wherein the outer layer 1 comprises 8 parts by weight of an open and smooth masterbatch, 40 parts by weight of ultra-low density polyethylene and 40 parts by weight of metallocene polyethylene, the intermediate layer 2 comprises 55 parts by weight of ultra-low density polyethylene and 45 parts by weight of metallocene polyethylene, the inner layer 3 comprises 8 parts by weight of an open and smooth masterbatch, 7 parts by weight of ultra-low density polyethylene and 65 parts by weight of metallocene polyethylene, and the interlayer ratio of the outer layer 1, the intermediate layer 2 and the inner layer 3 is 25%:50%:25%.

[0027] Among them, the open and smooth masterbatch is prepared by the following method: take 35 parts of stearyl stearic acid amide, use ultrasonic grinding for 70 minutes, then add 65 parts of polyethylene powder resin, heat to 60°C and stir for 30 minutes, add a screw machine for extrusion and granulation, and obtain the open and smooth masterbatch.

[0028] Energy-saving polyethylene shrink film is prepared by the following method:

[0029] Step 1: According to the components contained in each layer, the proportion of each component is measured respectively, and after being mixed evenly in a mixer, it is uniformly added to a three-stage co-extrusion extruder, heated to 185°C, stirred at a speed of 180rpm, and extruded into a three-layer co-extrusion die at a speed of 60rpm, and the extrusion temperature is 230°C;

[0030] Step 2: Raise the temperature of the three-layer co-extrusion die to 220°C, reduce the pressure to 300 Pa, react under this condition for 3 minutes to obtain a polymer melt, and then extrude, blow, ultra-fast cooling process cooling, corona and trim the prepared polymer melt in sequence to obtain the energy-saving polyethylene shrink film.

[0031] Example 2

[0032] The present embodiment provides an energy-saving polyethylene shrink film and a preparation method thereof. The energy-saving polyethylene shrink film comprises an outer layer 1, an intermediate layer 2 and an inner layer 3 which are connected in sequence, wherein the outer layer 1 comprises 1 part by weight of an open and smooth masterbatch, 50 parts by weight of ultra-low density polyethylene and 50 parts by weight of metallocene polyethylene, the intermediate layer 2 comprises 45 parts by weight of ultra-low density polyethylene and 55 parts by weight of metallocene polyethylene, the inner layer 3 comprises 1 part by weight of an open and smooth masterbatch, 20 parts by weight of ultra-low density polyethylene and 75 parts by weight of metallocene polyethylene, and the interlayer ratio of the outer layer 1, the intermediate layer 2 and the inner layer 3 is 15%:70%:15%.

[0033] Among them, the open and smooth masterbatch is prepared by the following method: take 15 parts of stearyl stearic acid amide, use ultrasonic grinding for 5 minutes, then add 85 parts of polyethylene powder resin, heat to 60°C and stir for 10 minutes, add a screw machine for extrusion and granulation, and obtain the open and smooth masterbatch.

[0034] Energy-saving polyethylene shrink film is prepared by the following method:

[0035] Step 1: According to the components contained in each layer, the proportion of each component is measured respectively, and after being put into the mixer and mixed evenly, it is added to the three-stage co-extrusion extruder at a uniform speed, heated to 160°C, stirred at a speed of 150rpm, and extruded into the three-layer co-extrusion die at a speed of 60rpm, and the extrusion temperature is 200°C;

[0036] Step 2: Raise the temperature of the three-layer co-extrusion die to 200°C and reduce the pressure to 200 Pa. Under this condition, react for 1 minute to obtain a polymer melt. Then, extrude, blow, cool by ultra-fast cooling process, corona and trim the prepared polymer melt in sequence to obtain the energy-saving polyethylene shrink film.

[0037] Example 3

[0038] The present embodiment provides an energy-saving polyethylene shrink film and a preparation method thereof. The energy-saving polyethylene shrink film comprises an outer layer 1, an intermediate layer 2 and an inner layer 3 which are connected in sequence, wherein the outer layer 1 comprises 4 parts by weight of an open and smooth masterbatch, 45 parts of ultra-low density polyethylene and 45 parts of metallocene polyethylene, the intermediate layer 2 comprises 50 parts by weight of ultra-low density polyethylene and 50 parts of metallocene polyethylene, the inner layer 3 comprises 5 parts by weight of an open and smooth masterbatch, 15 parts of ultra-low density polyethylene and 70 parts of metallocene polyethylene, and the interlayer ratio of the outer layer 1, the intermediate layer 2 and the inner layer 3 is 20%:60%:20%.

[0039] Among them, the open and smooth masterbatch is prepared by the following method: take 25 parts of stearyl stearic acid amide, use ultrasonic grinding for 40 minutes, then add 75 parts of polyethylene powder resin, heat to 60°C and stir for 20 minutes, add a screw machine for extrusion and granulation, and obtain the open and smooth masterbatch.

[0040] Energy-saving polyethylene shrink film is prepared by the following method:

[0041] Step 1: According to the components contained in each layer, the proportion of each component is measured respectively, and after being mixed evenly in a mixer, it is added to a three-stage co-extrusion extruder at a uniform speed, heated to 175°C, stirred at a speed of 165rpm, and extruded into a three-layer co-extrusion die at a speed of 60rpm, and the extrusion temperature is 210°C;

[0042] Step 2: Raise the temperature of the three-layer co-extrusion die to 210°C and reduce the pressure to 280 Pa. Under this condition, react for 2 minutes to obtain a polymer melt. Then, extrude, blow, ultra-fast cooling process cool, corona and trim the prepared polymer melt in sequence to obtain the energy-saving polyethylene shrink film.

[0043] Comparative Example 1

[0044] The present comparative example provides a polyethylene shrink film and a preparation method thereof. The polyethylene shrink film comprises an outer layer 1, an intermediate layer 2 and an inner layer 3 which are connected in sequence, wherein the outer layer 1 comprises 4 parts by weight of an open-ended smooth masterbatch, 45 parts by weight of an ultra-low density polyethylene and 45 parts by weight of a metallocene polyethylene, the intermediate layer 2 comprises 50 parts by weight of an ultra-low density polyethylene and 50 parts by weight of a metallocene polyethylene, the inner layer 3 comprises 5 parts by weight of an open-ended smooth masterbatch, 15 parts by weight of a high-density polyethylene and 70 parts by weight of a metallocene polyethylene, and the interlayer ratio of the outer layer 1, the intermediate layer 2 and the inner layer 3 is 20%:60%:20%.

[0045] Among them, the open and smooth masterbatch is prepared by the following method: take 25 parts of stearyl stearic acid amide, use ultrasonic grinding for 40 minutes, then add 75 parts of polyethylene powder resin, heat to 60°C and stir for 20 minutes, add a screw machine for extrusion and granulation, and obtain the open and smooth masterbatch.

[0046] Polyethylene shrink film is prepared by the following method:

[0047] Step 1: According to the components contained in each layer, the proportion of each component is measured respectively, and after being mixed evenly in a mixer, it is added to a three-stage co-extrusion extruder at a uniform speed, heated to 175°C, stirred at a speed of 165rpm, and extruded into a three-layer co-extrusion die at a speed of 60rpm, and the extrusion temperature is 210°C;

[0048] Step 2: Raise the temperature of the three-layer co-extrusion die to 210° C. and reduce the pressure to 280 Pa. Under this condition, react for 2 minutes to obtain a polymer melt. Then, extrude, blow, ultra-fast cooling process cool, corona and trim the prepared polymer melt in sequence to obtain the polyethylene shrink film.

[0049] Comparative Example 2

[0050] The present comparative example provides a polyethylene shrink film and a preparation method thereof. The polyethylene shrink film comprises an outer layer 1, an intermediate layer 2 and an inner layer 3 which are connected in sequence, wherein the outer layer 1 comprises 4 parts by weight of an open slippery masterbatch, 45 parts by weight of an ultra-low density polyethylene and 45 parts by weight of a metallocene polyethylene, the intermediate layer 2 comprises 50 parts by weight of an ultra-low density polyethylene and 50 parts by weight of a metallocene polyethylene, the inner layer 3 comprises 5 parts by weight of an open slippery masterbatch, 15 parts by weight of an ultra-low density polyethylene and 70 parts by weight of a metallocene polyethylene, and the interlayer ratio of the outer layer 1, the intermediate layer 2 and the inner layer 3 is 1:1:1.

[0051] Among them, the open and smooth masterbatch is prepared by the following method: take 25 parts of stearyl stearic acid amide, use ultrasonic grinding for 40 minutes, then add 75 parts of polyethylene powder resin, heat to 60°C and stir for 20 minutes, add a screw machine for extrusion and granulation, and obtain the open and smooth masterbatch.

[0052] Polyethylene shrink film is prepared by the following method:

[0053] Step 1: According to the components contained in each layer, the proportion of each component is measured respectively, and after being mixed evenly in a mixer, it is added to a three-stage co-extrusion extruder at a uniform speed, heated to 175°C, stirred at a speed of 165rpm, and extruded into a three-layer co-extrusion die at a speed of 60rpm, and the extrusion temperature is 210°C;

[0054] Step 2: Raise the temperature of the three-layer co-extrusion die to 210° C. and reduce the pressure to 280 Pa. Under this condition, react for 2 minutes to obtain a polymer melt. Then, extrude, blow, ultra-fast cooling process cool, corona and trim the prepared polymer melt in sequence to obtain the polyethylene shrink film.

[0055] Application Example 1

[0056] The energy-saving polyethylene shrink film prepared in Example 3 was subjected to performance tests, and the results are shown in the following table:

[0057]

[0058] Application Example 2

[0059] The products prepared in Examples 1-3 and Comparative Examples 1-2 were tested for performance and the results are shown in the following table:

[0060]

[0061]

[0062] Application Example 3

[0063] The products obtained in Example 3 and Comparative Example 2 were subjected to heat shrinkage tests, and the results are shown in the following table:

[0064]

[0065] Note: Every 10°C drop in the shrink channel temperature can save 5% of electricity.

[0066] Result analysis: It can be seen from the above experimental data that the polyethylene heat shrinkable film prepared by the present invention can be applied to a lower heat shrinkage temperature, so the intended purpose of the present invention is achieved.

[0067] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

[0068] Although the terms such as outer layer 1, middle layer 2, inner layer 3 are used more frequently in this article, the possibility of using other terms is not excluded. These terms are used only to more conveniently describe and explain the essence of the present invention; interpreting them as any additional restrictions is contrary to the spirit of the present invention.

Claims

1. An energy-saving polyethylene shrink film, comprising an outer layer (1), an intermediate layer (2) and an inner layer (3) connected in sequence, characterized in that: The outer layer (1) comprises an open-ended smooth masterbatch, ultra-low density polyethylene and metallocene polyethylene, the middle layer (2) comprises ultra-low density polyethylene and metallocene polyethylene, the inner layer (3) comprises an open-ended smooth masterbatch, ultra-low density polyethylene and metallocene polyethylene, and the interlayer ratio of the outer layer (1), the middle layer (2) and the inner layer (3) is 15-25%: 50-70%: 15-25%.

2. The energy-saving polyethylene shrink film according to claim 1, characterized in that: The outer layer (1) is composed of open-ended smooth masterbatch, ultra-low density polyethylene and metallocene polyethylene, the middle layer (2) is composed of ultra-low density polyethylene and metallocene polyethylene, and the inner layer (3) is composed of open-ended smooth masterbatch, ultra-low density polyethylene and metallocene polyethylene.

3. The energy-saving polyethylene shrink film according to claim 2, characterized in that: The open and smooth masterbatch is prepared by the following method: 15-35 parts of anti-adhesion polymer are taken, and ultrasonic grinding is used for 5-70 minutes, and then 65-85 parts of polyethylene powder resin are added, the temperature is raised to 60° C. and stirred for 10-30 minutes, and a screw machine is added for extrusion and granulation to obtain the open and smooth masterbatch.

4. The energy-saving polyethylene shrink film according to claim 3, characterized in that: The anti-adhesion polymer is a single component or a compound composition of an organic silicon polymer and a fatty acid amide polymer.

5. The energy-saving polyethylene shrink film according to claim 3, characterized in that: The anti-adhesion polymer includes one or more of silicone powder, stearyl stearic acid amide, stearyl erucic acid amide, behenic acid amide and ethylene bis stearic acid amide.

6. The energy-saving polyethylene shrink film according to claim 1, characterized in that: The outer layer (1) comprises 1-8 parts by weight of open-ended smooth masterbatch, 40-50 parts by weight of ultra-low density polyethylene and 40-50 parts by weight of metallocene polyethylene.

7. The energy-saving polyethylene shrink film according to claim 1, characterized in that: The intermediate layer (2) comprises 45-55 parts by weight of ultra-low density polyethylene and 45-55 parts by weight of metallocene polyethylene.

8. The energy-saving polyethylene shrink film according to claim 1, characterized in that: The inner layer (3) comprises 1-8 parts by weight of open-ended smooth masterbatch, 7-20 parts by weight of ultra-low density polyethylene and 65-75 parts by weight of metallocene polyethylene.

9. The energy-saving polyethylene shrink film according to claim 1, characterized in that: The total thickness of the energy-saving polyethylene shrink film is less than 50 μm, and the heat shrinkage temperature is less than 120° C.

10. A method for preparing the energy-saving polyethylene shrink film according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step 1: According to the components contained in each layer, the proportion of each component is measured respectively, and after being mixed evenly in a mixer, it is uniformly added to a three-stage co-extrusion extruder, heated to 160-185°C, stirred at a speed of 150-180rpm, and extruded into a three-layer co-extrusion die at a speed of 60rpm, and the extrusion temperature is 200-230°C; Step 2: Raise the temperature of the three-layer co-extrusion die to 200-220°C, reduce the pressure to below 300Pa, react under this condition for 1-3min to obtain a polymer melt, and then extrude, blow, ultra-fast cooling process cooling, corona and trim the prepared polymer melt in sequence to obtain the energy-saving polyethylene shrink film.

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