Preparation method of composite membrane

Abstract

The invention discloses a preparation method of a composite film, which comprises the following steps: mixing PE resin with a slipping agent at an ambient temperature of 20-25 DEG C, heating the mixture to a molten state, extruding and granulating, heating the particles to a molten state, attaching the particles to a base film in a casting manner, and cooling and shaping, the environment humidity is 50%-60%, the environment temperature during cooling and shaping is 20-25 DEG C, and the environment humidity is 50%-60%. The composite film prepared by the preparation method has the following beneficial effects that the PE cast film prepared by mixing the PE resin and the slipping agent is compounded with the base film, so that the smooth degree of the PE cast film in the composite film is improved.

Description

Technical Field

[0001] The invention relates to the field of packaging film materials, and in particular to a method for preparing a composite film. Background Art

[0002] PET film is a commonly used packaging film at present. Since PET film cannot be heat-sealed, many PET film materials now choose to laminate a layer of PE film on the PET film by laminating PE resin, thereby forming a composite film of PET film and PE. The resin surface of the PE film obtained by extrusion laminating with PE resin is relatively rough, and the friction coefficient between PE films is as high as 0.5-0.7. Since the composite film relies on PE film for heat sealing during packaging or bag making (that is, the PE film is located on the inside, and the PE film will contact the packaged items after packaging), the PE film is too rough and is not conducive to the packaging of some items. Summary of the invention

[0003] In view of the above problems, the present invention proposes a method for preparing a composite film, in which a PE cast film and a base film are composited by mixing PE resin and a lubricant, thereby improving the smoothness of the PE cast film in the composite film.

[0004] The technical solution adopted by the present invention is as follows:

[0005] A method for preparing a composite film comprises mixing a PE resin and a lubricant, and then heating the mixture to a molten state and extruding the mixture into granules, and then heating the granules to a molten state and attaching them to a base film in a casting manner, and then cooling and shaping.

[0006] In the preparation method of the composite film, a lubricant is mixed into a PE resin, the PE resin and the lubricant are mixed and granulated to obtain particles, and then the particles are heated to a molten state and attached to a base film in a casting manner, and finally a composite film composed of a base film and a PE film is obtained. Since the lubricant is added to the PE resin, the smoothness of the PE film layer in the prepared composite film is improved. Compared with the PE cast film and PE laminating film without adding the lubricant, the surface of the PE cast film with the lubricant added is smoother.

[0007] Specifically, when heat-sealing the composite film, PE cast film is used for heat sealing.

[0008] In summary, in this composite film, the PE cast film and the base film are composited by mixing the PE resin and the lubricant, thereby improving the smoothness of the PE cast film in the composite film.

[0009] Optionally, the ambient temperature when the PE resin and the lubricant are mixed is 20° C.-25° C., and the ambient humidity is 50%-60%.

[0010] Optionally, the mass ratio of PE resin to lubricant during mixing is 1:0.1.

[0011] Optionally, the temperature of the mixture during extrusion granulation is 200° C.-220° C., and the extrusion pressure is 1.5 MPa-2 MPa.

[0012] Optionally, the temperature of the melt during casting is 330° C. and the casting speed is 5-10 m / min.

[0013] Optionally, the ambient temperature during cooling and shaping is 20°C-25°C, and the ambient humidity is 50%-60%.

[0014] Optionally, the base film includes a PET film.

[0015] The specific base film includes but is not limited to a PET film, and may also be other films with properties similar to the PET film.

[0016] The beneficial effects of the present invention are as follows: the PE cast film and the base film are composited by mixing the PE resin and the lubricant, thereby improving the smoothness of the PE cast film in the composite film. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0018] Figure 1 It is a schematic diagram of the structure of the composite membrane;

[0019] The reference numerals in the figure are: 1, base film; 2, PE cast film. DETAILED DESCRIPTION

[0020] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0021] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0022] In the description of the present application, it should be noted that the terms used herein are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. For ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be regarded as part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as merely exemplary, rather than as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0023] Example 1

[0024] A method for preparing a composite film, wherein a PET film is selected as a base film, a PE resin and a lubricant are mixed at a mass ratio of 1:0.1, and the ambient temperature during mixing is 20°C-25°C, and the ambient humidity is 50%-60%. The mixture is then heated to a molten state and extruded for granulation. The temperature during extrusion granulation is 200°C-220°C, and the extrusion pressure is 1.5MPa-2MPa. After the particles are cooled, the particles are heated to a molten state and attached to the base film in a cast manner, wherein the temperature of the melt during casting is 330°C, and the casting speed is 5-10m / min. Finally, the film is cooled and shaped. The ambient temperature during cooling and shaping is 20°C-25°C, and the ambient humidity is 50%-60%. In this embodiment, the lubricant is a PE700 lubricant of the Shanghai Lingding brand. Finally, the structure of the composite film prepared in this embodiment is roughly as shown in the attached figure. Figure 1 As described in the above, it is composed of a PE cast film 2 and a base film 1.

[0025] Comparative Example 1

[0026] A method for preparing a composite film, wherein a PET film is selected as a base film, a PE resin and a lubricant are mixed in a mass ratio of 1:0.1, and the ambient temperature during mixing is 20°C-25°C, and the ambient humidity is 50%-60%, and then the mixture is heated to a molten state and extruded for granulation, the temperature during extrusion granulation is 200°C-220°C, and the extrusion pressure is 1.5MPa-2MPa, and after the particles are cooled, the particles are heated to a molten state and attached to the base film in the form of a coating, wherein the temperature of the melt during the coating is 330°C, and the speed during the casting is 5-10m / min, and finally cooled and shaped, and the ambient temperature during the cooling and shaping is 20°C-25°C, and the ambient humidity is 50%-60%. In this embodiment, the lubricant is a PE700 lubricant of Shanghai Lingding brand. In the composite film prepared in this embodiment, the thickness of the PE coating is the same as the thickness of the PE cast film in Example 1.

[0027] Comparative Example 2

[0028] A method for preparing a composite film, wherein a PET film is selected as a base film, a PE resin is heated to a molten state and then extruded and granulated, the temperature during extrusion and granulation is 200°C-220°C, the extrusion pressure is 1.5MPa-2MPa, the particles are heated to a molten state after cooling and attached to the base film in a casting manner, wherein the temperature of the melt during casting is 330°C, the speed during casting is 5-10m / min, and finally cooled and shaped, the ambient temperature during cooling and shaping is 20°C-25°C, and the ambient humidity is 50%-60%. In the composite film prepared in this embodiment, the thickness of the PE cast film is the same as the thickness of the PE cast film in Example 1.

[0029] Comparative Example 3

[0030] A method for preparing a composite film, wherein a PET film is selected as a base film, a PE resin is heated to a molten state and then extruded and granulated, the temperature during extrusion and granulation is 200°C-220°C, the extrusion pressure is 1.5MPa-2MPa, the particles are heated to a molten state after cooling and attached to the base film in a coating manner, wherein the temperature of the melt during coating is 330°C, the coating speed is 5-10m / min, and finally cooled and shaped, the ambient temperature during cooling and shaping is 20°C-25°C, and the ambient humidity is 50%-60%. In the composite film prepared in this embodiment, the thickness of the PE cast film is the same as that of the PE cast film in Example 1.

[0031] Comparative Example 4

[0032] PET film is selected as the base film, and the lubricant is heated to a molten state and then extruded and granulated to obtain lubricant particles. The temperature during extrusion granulation is 200°C-220°C, and the extrusion pressure is 1.5MPa-2MPa. After the lubricant particles are cooled, the particles are heated to a molten state and attached to the base film in a casting manner, wherein the temperature of the melt during casting is 330°C, and the speed during casting is 5-10m / min. Finally, the film is cooled and shaped. The ambient temperature during cooling and shaping is 20°C-25°C, and the ambient humidity is 50%-60%. In this embodiment, the lubricant is a PE700 lubricant of Shanghai Lingding brand. The composite film prepared in this embodiment is a composite film of PET film and lubricant film, wherein the thickness of the lubricant film is the same as the thickness of the PE cast film in Example 1.

[0033] The smoothness of Example 1 and Control Examples 1 to 4 was tested. The test selected a steel block in contact with the membrane surface. In Example 1, Control Example 1, Control Example 2 and Control Example 3, the steel block was in contact with the PE film, and in Control Example 4, the steel block was in contact with the lubricating film. The above data were detected and recorded.

[0034] Similarly, the composite films prepared in Example 1 and Control Examples 1 to 4 were tested for light transmittance, barrier properties, tensile strength and heat resistance. The test results are summarized in the following table.

[0035] Table 1

[0036] Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Light Transmittance 87％ 82％ 84％ 78％ 80％ Barrier properties 87 95 90 89 85 tensile strength 95 92 90 89 94 Heat resistance 87 85 82 81 95 Friction coefficient 0.23 0.32 0.30 0.33 0.20

[0037] The transparency in the above table is measured by using a spectrophotometer under the premise that the thickness of the composite film is constant, and a visible light with a wavelength of 560nm is used for measurement.

[0038] The barrier properties in the above table are selected by measuring the oxygen transmission rate (unit: cc-25um / m 2 -day) to represent its barrier properties.

[0039] The tensile strength in the above table is measured in MPa using a plastic film tensile strength testing machine to test the tensile strength of several composite films.

[0040] The heat resistance in the above table is measured by heat deformation temperature test method, and the test standard is based on GB / T1634.2.

[0041] Combined with the data in Table 1 above, it can be seen that in this embodiment, by adding PE700 type lubricant to PE resin and preparing the composite film by composite of cast film and PET film, the surface of the composite film finally prepared is smoother than that of the composite film composited with pure PE resin and PET film.

[0042] Comparing the data in Table 1, it can be seen that the composite film obtained by casting has a smoother surface than the composite film obtained by laminating.

[0043] Comparing the data in Table 1, it can be seen that the composite film obtained by casting has stronger tensile strength than the composite film obtained by laminating. The reason may be that the casting method can give the two layers of film a stronger composite strength. And the composite film with the addition of lubricant also has stronger tensile strength than the composite film without the addition of lubricant.

[0044] At the same time, by comparing the two parameters of barrier direction and friction coefficient in Table 1, it can be seen that although the use of pure lubricant can make the surface of the final composite film smoother, it will also reduce the light transmittance of the entire composite film.

[0045] At the same time, by comparing the data in Table 1, it can be seen that by comparing the heat resistance data of Example 1 and Control Example 4, the higher the content of the lubricant, the stronger the heat resistance can be given to the entire film, but the presence of the lubricant will make the light transmittance of the entire composite film.

[0046] In summary, in the preparation method disclosed in the present application, PE resin and lubricant are mixed, and then the two are compounded with PET film in a casting manner to form a composite film, ultimately ensuring that the entire composite film has good heat resistance and tensile strength while ensuring good light transmittance and barrier properties, and greatly improving the smoothness of the PE film side of the composite film.

[0047] The above-described embodiments only express some embodiments of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that for those skilled in the art, it is still possible to modify the technical solutions recorded in the above-mentioned embodiments, or to replace some of the technical features therein with equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a composite film, It is characterized in that The PE resin is mixed with the lubricant, and then the mixture is heated to a molten state and extruded into granules. The granules are then heated to a molten state and attached to the base film in a casting manner, and then cooled to set.

2. A method for preparing a composite membrane according to claim 1, It is characterized in that The ambient temperature when the PE resin and the lubricant are mixed is 20° C.-25° C., and the ambient humidity is 50%-60%.

3. The method for preparing a composite film according to claim 1, It is characterized in that The mass ratio of PE resin to lubricant during mixing is 1:0.

1.

4. The method for preparing a composite film according to claim 1, It is characterized in that The temperature of the mixture during extrusion granulation is 200°C-220°C, and the extrusion pressure is 1.5MPa-2MPa.

5. The method for preparing a composite membrane according to claim 1, It is characterized in that The temperature of the melt during casting was 330°C and the casting speed was 5-10 m / min.

6. The method for preparing a composite membrane according to claim 1, It is characterized in that The ambient temperature during cooling and shaping is 20℃-25℃, and the ambient humidity is 50%-60%.

7. The method for preparing a composite membrane according to claim 1, It is characterized in that The base film includes a PET film.

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