CN112848585A

CN112848585A - PE (polyethylene) stretching and winding film and preparation process thereof

Info

Publication number: CN112848585A
Application number: CN201911176606.XA
Authority: CN
Inventors: 唐彬彬; 黄阳
Original assignee: Shanghai Lixu Electromechanical Equipment Co ltd
Current assignee: Ningbo Yuanxiang New Material Co ltd
Priority date: 2019-11-26
Filing date: 2019-11-26
Publication date: 2021-05-28
Anticipated expiration: 2039-11-26
Also published as: CN112848585B

Abstract

The invention discloses a PE stretching and winding film which is formed by co-extruding three materials of an outer layer, a middle layer and an inner layer; the outer layer material comprises the following components in parts by mass: 60-80 parts of linear low-density polyethylene, 3-8 parts of linear medium-density polyethylene and 6-12 parts of metallocene; the middle layer material comprises the following components in parts by mass: 55-70 parts of linear low-density polyethylene, 2-6 parts of linear medium-density polyethylene and 5-10 parts of metallocene; the inner layer material comprises the following components in percentage by mass: 50-70 parts of linear low-density polyethylene, 2-8 parts of metallocene and 1-5 parts of tackifier. The PE stretch winding film disclosed by the invention is higher in uniformity and flatness, high in transparency and excellent in puncture resistance and tear resistance.

Description

PE (polyethylene) stretching and winding film and preparation process thereof

Technical Field

The invention relates to the technical field of packaging materials, in particular to a PE stretch winding film and a preparation process thereof.

Background

The PE stretch winding film has the advantages of strong tensile strength, large elongation, good self-adhesion, puncture resistance, tearing resistance and the like, can be used for manual winding films and machine winding films, and is widely applied to flexible packaging of chemical products, electronic product boxes, ceramic products, electromechanical equipment and the like.

The winding film has the following characteristics: (1) unitization: the unitization is one of the biggest characteristics of the wrapping film package, and the products are compactly and fixedly bundled into a unit by virtue of the ultra-strong wrapping force and retractility of the film, so that scattered small parts are integrated, and the products are not loosened or separated at all even under the adverse environment; (2) primary protection: the primary protectiveness provides surface protection of the product, and a very light and protective appearance is formed around the product, so that the aims of dust prevention, oil prevention, moisture prevention, water prevention and theft prevention are fulfilled; (3) cost saving: the winding film is used for packaging products, so that the use cost can be effectively reduced, the cost is only about 15% of that of log box packaging, about 35% of that of heat shrinkage film and about 50% of that of carton packaging, meanwhile, the labor intensity of workers can be reduced, and the packaging efficiency and the packaging grade are improved.

At present, the PE stretch wrap film is widely applied to industries such as industrial enterprises, food processing, material flow bags and the like, and plays roles of fixing, preventing water and dust and protecting wrapped objects for packaged products. However, the conventional PE stretch wrap film has poor film uniformity, large thickness error, low longitudinal elongation, low yield point, poor transverse tear strength, poor puncture resistance and tear resistance in the actual use process, and cannot meet the large-scale application.

Disclosure of Invention

In order to solve the problems in the background art, the invention aims to provide a PE stretch wrap film which has high uniformity and flatness, high transparency and excellent puncture resistance and tear resistance. In addition, the invention also provides a preparation process of the PE stretch winding film.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a PE stretching and winding film, which is formed by co-extruding an outer layer, a middle layer and an inner layer;

the outer layer material comprises the following components in parts by mass: 60-80 parts of Linear Low Density Polyethylene (LLDPE), 3-8 parts of Linear Medium Density Polyethylene (LMDPE) and 6-12 parts of Metallocene (MPE);

the middle layer material comprises the following components in parts by mass: 55-70 parts of Linear Low Density Polyethylene (LLDPE), 1-3 parts of Linear Medium Density Polyethylene (LMDPE) and 5-10 parts of Metallocene (MPE);

the inner layer material comprises the following components in percentage by mass: 50-70 parts of Linear Low Density Polyethylene (LLDPE), 2-8 parts of Metallocene (MPE) and 1-5 parts of tackifier.

In the formula, Linear Low Density Polyethylene (LLDPE) has higher softening temperature and melting temperature, also has the advantages of high strength, good toughness, high rigidity, heat resistance, good cold resistance and the like, also has good environmental stress crack resistance, impact strength, tear strength and the like, and is used as a main material of the PE stretching and winding film, metallocene is added into the Linear Low Density Polyethylene (LLDPE), and the metallocene is a high-stereospecific polymer and has narrow molecular weight distribution, so that the physical properties of the polymer can be accurately controlled, and the tensile strength, the puncture resistance and the tear resistance of the PE stretching and winding film can be obviously improved by adding the metallocene; the tackifier is also added into the inner layer material, so that the winding film has a certain viscosity effect, and the packaging protection effect on goods is better; the outer layer material and the middle layer material are added with a proper amount of Linear Medium Density Polyethylene (LMDPE), which can increase the density of the outer layer material and the inner layer material, improve the orientation degree of the outer layer material and the inner layer material, increase the transparency of the winding film, and improve the comprehensive performance of the film layer.

Preferably, the outer layer material, the middle layer material and the inner layer material further comprise Low Density Polyethylene (LDPE), and the mass ratio of Metallocene (MPE) to Low Density Polyethylene (LDPE) in each layer material is 1: (0.1-0.5). The addition of the metallocene can obviously improve the elongation, puncture resistance and tear resistance of the PE stretch wrapping film, but because the metallocene has narrow molecular weight distribution and narrow processing range and the processing conditions are difficult to control, a certain amount of low-density polyethylene (LDPE) is added into the metallocene to reduce the melt viscosity, the processing process is easy to regulate and control, and the flatness of the wrapping film is improved.

Preferably, the tackifier is Polyisobutylene (PIB) or ultra low density polyethylene (VLDPE). Good viscosity can make the outer packaging film layer of goods stick together with the layer and make the goods firm, selects Polyisobutylene (PIB) or ultra low density polyethylene (VLDPE) as the tackifier, can make the tackifier migrate to the inlayer with faster speed after the winding film production, can reach better viscidity effect, and the viscidity is comparatively stable. The viscosity of the winding film prepared by adopting the tackifier is influenced by temperature, the viscosity is strong when the temperature is higher than 30 ℃, and the viscosity is poor when the temperature is lower than 15 ℃, so that the storage temperature of the finished winding film is 15-25 ℃.

Preferably, the mass ratio of the outer layer material, the middle layer material and the inner layer material is 1: (2-5): (0.5-1.5).

Preferably, the PE stretch wrap film has a thickness of 23-28 μm.

In a second aspect of the present invention, a preparation process of the PE stretch wrap film is provided, which includes the following steps:

s1, adding the components in the outer layer material, the middle layer material and the inner layer material into three stirring containers respectively according to corresponding proportions, and stirring and mixing uniformly;

s2, respectively carrying out high-temperature extrusion on the mixture obtained in the step S1 through a screw extruder to obtain outer-layer plastic particles, middle-layer plastic particles and inner-layer plastic particles;

s3, respectively adding the outer layer plastic particles, the middle layer plastic particles and the inner layer plastic particles obtained in the step S2 into corresponding cavities of a casting machine, and forming a film through casting, wherein the casting temperature is 250-280 ℃, the temperature of a casting cooling roller is 20-30 ℃, and then the PE stretch winding film is obtained through winding and packaging, and the winding tension is not more than 10 Kg.

Preferably, in the step S2, the heating temperature in the screw extruder is 190-220 ℃.

In the preparation process, the influence of the temperature of the casting cooling roller on the performance of the winding film is high, when the temperature of the casting cooling roller is increased, the yield strength of the winding film is improved, but the other performances are reduced, the temperature of the casting cooling roller is controlled to be 20-30 ℃, and the comprehensive performance of the winding film in all aspects is ensured; the winding tension can influence the flatness and the winding tightness of the winding film, the winding tension is overlarge, stress can remain in the winding film, the properties of the winding film such as elongation and the like are reduced, and the film breaking phenomenon is easily caused, and the winding tension is controlled to be not more than 10 Kg.

Compared with the prior art, the invention has the following beneficial effects:

the invention selects Linear Low Density Polyethylene (LLDPE) as the main material of the PE stretch winding film, which has higher softening temperature and melting temperature, and also has the advantages of high strength, good toughness, high rigidity, good heat resistance and cold resistance, and the like, and also has good environmental stress crack resistance, impact strength, tearing strength and other properties; the metallocene is added into the PE stretch wrap film, so that the tensile strength, the puncture resistance and the tear resistance of the PE stretch wrap film can be obviously improved; the tackifier is also added into the inner layer material, so that the winding film has a certain viscosity effect, and the packaging protection effect on goods is better; the outer layer material and the middle layer material are added with a proper amount of Linear Medium Density Polyethylene (LMDPE), which can increase the density of the outer layer material and the inner layer material, improve the orientation degree of the outer layer material and the inner layer material, increase the transparency of the winding film and improve the comprehensive performance of the film layer.

The PE stretch winding film has reasonable formula of each layer of material, adopts a three-layer co-extrusion process, strictly controls the casting temperature and the winding tension, has uniform thickness and high transparency of the prepared winding film, and also has excellent tensile strength and puncture resistance.

Drawings

The invention is described in further detail below with reference to specific embodiments and with reference to the following drawings.

FIG. 1 is a flow chart of a process for producing a PE stretch wrap film according to the present invention.

Detailed Description

Example 1

The PE stretch winding film in the embodiment is formed by co-extruding an outer layer material, a middle layer material and an inner layer material, wherein the mass ratio of the outer layer material to the middle layer material to the inner layer material is 1: 3: 1, the PE stretch wrap film had a thickness of 24 μm.

The outer layer material comprises the following components in parts by mass: 68 parts of Linear Low Density Polyethylene (LLDPE), 4 parts of Linear Medium Density Polyethylene (LMDPE) and 8 parts of Metallocene (MPE);

the middle layer material comprises the following components in parts by mass: 60 parts of Linear Low Density Polyethylene (LLDPE), 3 parts of Linear Medium Density Polyethylene (LMDPE) and 7 parts of Metallocene (MPE);

the inner layer material comprises the following components in percentage by mass: 56 parts of linear low-density polyethylene (LLDPE), 2 parts of Metallocene (MPE) and 3 parts of tackifier.

Wherein the tackifier is Polyisobutylene (PIB).

As shown in fig. 1, the preparation process of the PE stretch wrap film in this embodiment includes the following steps:

s2, respectively carrying out high-temperature extrusion on the mixture obtained in the step S1 through a screw extruder to obtain outer-layer plastic particles, middle-layer plastic particles and inner-layer plastic particles; wherein the heating temperature in the screw extruder is 190-220 ℃;

Example 2

The PE stretch winding film in the embodiment is formed by co-extruding an outer layer material, a middle layer material and an inner layer material, wherein the mass ratio of the outer layer material to the middle layer material to the inner layer material is 1: 2: 0.5, the PE stretch wrap film had a thickness of 26 μm.

The outer layer material comprises the following components in parts by mass: 60 parts of Linear Low Density Polyethylene (LLDPE), 3 parts of Linear Medium Density Polyethylene (LMDPE) and 6 parts of Metallocene (MPE);

the middle layer material comprises the following components in parts by mass: 55 parts of Linear Low Density Polyethylene (LLDPE), 2 parts of Linear Medium Density Polyethylene (LMDPE) and 5 parts of Metallocene (MPE);

the inner layer material comprises the following components in percentage by mass: 50 parts of Linear Low Density Polyethylene (LLDPE), 5 parts of Metallocene (MPE) and 5 parts of tackifier.

The outer layer material, the middle layer material and the inner layer material further comprise Low Density Polyethylene (LDPE), and the mass ratio of Metallocene (MPE) to the Low Density Polyethylene (LDPE) in each layer material is 1: 0.2.

wherein the tackifier is ultra low density polyethylene (VLDPE).

The process for producing the PE stretch wrap film in this example can be referred to in example 1.

Example 3

The PE stretch winding film in the embodiment is formed by co-extruding an outer layer material, a middle layer material and an inner layer material, wherein the mass ratio of the outer layer material to the middle layer material to the inner layer material is 1: 5: 1.5, the thickness of the PE stretch wrap film was 23 μm.

The outer layer material comprises the following components in parts by mass: 74 parts of Linear Low Density Polyethylene (LLDPE), 8 parts of Linear Medium Density Polyethylene (LMDPE) and 12 parts of Metallocene (MPE);

the middle layer material comprises the following components in parts by mass: 65 parts of Linear Low Density Polyethylene (LLDPE), 1 part of Linear Medium Density Polyethylene (LMDPE) and 10 parts of Metallocene (MPE);

the inner layer material comprises the following components in percentage by mass: 70 parts of Linear Low Density Polyethylene (LLDPE), 6 parts of Metallocene (MPE) and 1 part of tackifier.

The outer layer material, the middle layer material and the inner layer material further comprise Low Density Polyethylene (LDPE), and the mass ratio of Metallocene (MPE) to the Low Density Polyethylene (LDPE) in each layer material is 1: 0.1.

wherein the tackifier is Polyisobutylene (PIB).

Example 4

The PE stretch winding film in the embodiment is formed by co-extruding an outer layer material, a middle layer material and an inner layer material, wherein the mass ratio of the outer layer material to the middle layer material to the inner layer material is 1: 3: 0.8, the PE stretch wrap film had a thickness of 28 μm.

The outer layer material comprises the following components in parts by mass: 80 parts of Linear Low Density Polyethylene (LLDPE), 6 parts of Linear Medium Density Polyethylene (LMDPE) and 8 parts of Metallocene (MPE);

the middle layer material comprises the following components in parts by mass: 70 parts of Linear Low Density Polyethylene (LLDPE), 2 parts of Linear Medium Density Polyethylene (LMDPE) and 6 parts of Metallocene (MPE);

the inner layer material comprises the following components in percentage by mass: 68 parts of linear low-density polyethylene (LLDPE), 8 parts of Metallocene (MPE) and 3 parts of tackifier.

The outer layer material, the middle layer material and the inner layer material further comprise Low Density Polyethylene (LDPE), and the mass ratio of Metallocene (MPE) to the Low Density Polyethylene (LDPE) in each layer material is 1: 0.5.

wherein the tackifier is ultra low density polyethylene (VLDPE).

Comparative example 1

Comparative example 1 is a comparative test to example 2, the two being distinguished by: in comparative example 1, no metallocene was added to the materials of the outer layer, the middle layer and the inner layer, and the formulation and preparation process flow were the same as those in example 2.

Comparative example 2

Comparative example 2 is a comparative test to example 2, the two being distinguished by: in comparative example 1, no linear medium density polyethylene was added to the outer layer and the middle layer, and the formulation and preparation process flow were the same as in example 2.

Test examples

Tensile strength and elongation at break of the PE stretch wrap films prepared in examples 1 to 4, comparative example 1 and comparative example 2 were measured in accordance with GB/T1040.3-2006, and the specific test results are shown in Table 1.

TABLE 1

	Tensile Strength (MPa)	Elongation at Break (%)
			Example 1	14.2	387
Example 2	15.6	392
			Example 3	14.5	384
Example 4	14.1	379
			Comparative example 1	8.6	245
Comparative example 2	9.7	264

As can be seen from the test results in table 1, the PE stretch wrap films prepared in examples 1 to 4 have excellent mechanical properties, and excellent tensile strength and puncture resistance. The metallocene is added into the formula, so that the tensile strength, puncture resistance and tear resistance of the PE stretch winding film can be obviously improved; and a proper amount of Linear Medium Density Polyethylene (LMDPE) is added into the outer layer material and the middle layer material, so that the comprehensive performance of the film layer can be improved.

The present invention has been described in terms of specific examples, which are provided to aid understanding of the invention and are not intended to be limiting. For a person skilled in the art to which the invention pertains, several simple deductions, modifications or substitutions may be made according to the idea of the invention.

Claims

1. A PE stretch winding film is characterized by being formed by co-extruding an outer layer material, a middle layer material and an inner layer material;

the outer layer material comprises the following components in parts by mass: 60-80 parts of linear low-density polyethylene, 3-8 parts of linear medium-density polyethylene and 6-12 parts of metallocene;

the middle layer material comprises the following components in parts by mass: 55-70 parts of linear low-density polyethylene, 1-3 parts of linear medium-density polyethylene and 5-10 parts of metallocene;

the inner layer material comprises the following components in percentage by mass: 50-70 parts of linear low-density polyethylene, 2-8 parts of metallocene and 1-5 parts of tackifier.

2. The PE stretch wrap film of claim 1, further comprising a low density polyethylene in the outer layer material, the middle layer material, and the inner layer material, wherein the ratio of metallocene to low density polyethylene in each layer material is 1: (0.1-0.5).

3. The PE stretch wrap film of claim 1 or 2, wherein the tackifier is polyisobutylene or ultra low density polyethylene.

4. The PE stretch wrap film according to claim 3, wherein a mass ratio of the outer layer material, the middle layer material, and the inner layer material is 1: (2-5): (0.5-1.5).

5. The PE stretch wrap film of claim 1, wherein the PE stretch wrap film has a thickness of 23-28 μ ι η.

6. A process for producing a PE stretch wrap film according to claim 1, comprising the steps of:

7. The process for preparing a PE stretch wrap film according to claim 6, wherein the heating temperature in the screw extruder in the step S2 is 190-220 ℃.