Method for preparing composite film by coextrusion of polar material and non-polar material

Abstract

The present invention belongs to the technical field of film production, and discloses a method for preparing a composite film by co-extrusion using polar materials and non-polar materials. The method comprises the following steps: pre-mixing polar materials, non-polar materials, and malic anhydride, and then co-extruding to obtain a composite film; the co-extrusion process includes melt treatment, and the temperature of the melt treatment is 130-280°C, and the pressure is 100-200 atmospheres. The present invention pre-mixes different polar polymer materials, adds a specific cross-linking agent malic anhydride, and chemically reacts at a specific temperature and pressure to modify polar materials and non-polar materials, and then obtains a composite film by a co-extrusion method, so as to achieve a one-time output composite film, and there is no need to use a coating or adhesive, simplify the production process, reduce production costs, and the purpose of strong bonding between the film layers of the composite film.

Description

Technical Field

[0001] The invention belongs to the technical field of film production, and particularly relates to a method for preparing a composite film by co-extrusion of polar materials and non-polar materials. Background Art

[0002] In order to take into account the performance of all aspects, most of the film products in the prior art adopt a multi-layer film composite structure. Generally, two or more films with different properties are composited by coating. Although the co-extrusion method can also be used in production to prepare a multi-layer film composite structure, the material of each layer of the co-extrusion method in the prior art uses a polymer material with similar polarity and similar melting point. If materials with large polarity differences are used, the interface bonding force of materials with large polarity differences in the co-extruded sheet is not strong, which easily causes the sheet to be delaminated, and the compatibility of materials with large melting point differences is also poor. In order to solve the problem of weak interface bonding force of materials with large polarity differences, the prior art solves this problem by coating composite or coating adhesive. However, from the perspective of cost, coating composite or coating adhesive increases production cost and material cost. The specific reasons are: first, the process is complicated, and the uniformity of the coating or adhesive and the control of the coating thickness are factors that affect product quality. If you are not careful, it will cause material waste; second, the investment and energy consumption of the coating or adhesive coating equipment, labor, and material loss caused by multiple machine loading all increase production costs.

[0003] Therefore, there is an urgent need to provide a new film preparation method that can solve the technical problems of complex process and poor film layer bonding in preparing composite films from polar and non-polar materials. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention proposes a method for preparing a composite film by co-extrusion of polar materials and non-polar materials, which can solve the technical problems of complex process and poor film layer bonding of polar materials and non-polar materials in preparing composite thin films. The method of the present invention does not require coating or adhesive, and the film layers of the prepared composite film have strong bonding.

[0005] The inventive concept of the present invention is: the present invention premixes different polar polymer materials (polar materials and non-polar materials), adds a specific cross-linking agent (malic anhydride), and undergoes a chemical reaction at a specific temperature and pressure (130-280°C, 100-200 atmospheres of pressure) to modify the polar materials and non-polar materials, and then obtains the composite film through a co-extrusion method, thereby achieving one-time production of the composite film without the need for using a coating or adhesive, thereby simplifying the production process, reducing the production cost, and achieving the purpose of strong bonding between the film layers of the composite film.

[0006] Polar materials for preparing polar layers, such as PET (polyethylene terephthalate), PBT (polybutylene terephthalate), PA (nylon), EVOH (ethylene-vinyl alcohol copolymer), etc., are added with non-polar materials such as PP (polypropylene) and PE (polyethylene) during the premixing stage to increase the bonding strength between the polar layer and the non-polar layer. In addition, the crosslinking agent malic anhydride needs to be added to increase the compatibility between the non-polar material and the polar material on the one hand, and on the other hand, after premixing, in the melting section of the extruder, after the viscous flow state is converted, a branching reaction occurs, so that the molecular groups in the polar material and the non-polar material are linked through the crosslinking agent, thereby achieving the purpose of material modification. The linked high molecular polymer contains both polar groups and non-polar groups, which increases the bonding strength between the polar layer and the non-polar layer.

[0007] The first aspect of the present invention provides a method for preparing a composite film by co-extrusion of polar materials and non-polar materials.

[0008] Specifically, the method for preparing a composite film by co-extrusion of a polar material and a non-polar material comprises the following steps:

[0009] Polar material, non-polar material and malic anhydride are premixed and then co-extruded to obtain a composite film; the co-extrusion process includes melting treatment, the temperature of the melting treatment is 130-280°C, and the pressure is 100-200 atmospheres.

[0010] Preferably, the temperature of the melt treatment is 135-255°C, and the pressure is 110-180 atmospheres; further preferably, the temperature of the melt treatment is 135-255°C, and the pressure is 120-160 atmospheres.

[0011] Preferably, the polar material is selected from at least one of PET (polyethylene terephthalate), PBT (polybutylene terephthalate), PA (nylon), and EVOH (ethylene vinyl alcohol copolymer).

[0012] Preferably, the non-polar material is selected from PP (polypropylene), PE (polyethylene), HDPE (high-density polyethylene, density of 0.941 to 0.960 g / cm 3 ) at least one of.

[0013] The composite membrane includes a polar layer and a non-polar layer.

[0014] Preferably, the method for preparing a composite film by coextrusion of polar materials and non-polar materials comprises the following steps:

[0015] Preparation of the polar layer: premixing polar materials, non-polar materials and malic anhydride, and then co-extruding; the co-extrusion process includes melt treatment, the melt treatment temperature is 130-280°C, and the pressure is 100-200 atmospheres;

[0016] Preparation of the non-polar layer: premixing polar material, non-polar material and malic anhydride, and then co-extruding; the co-extrusion process includes melt treatment, the melt treatment temperature is 130-280°C, and the pressure is 100-200 atmospheres;

[0017] During the preparation of the polar layer, the weight ratio of the polar material, the non-polar material, and the malic anhydride is 100:(3-25):(0.2-2.5);

[0018] During the preparation of the non-polar layer, the weight ratio of the polar material, the non-polar material and the malic anhydride is 3-25:100:(0.2-2.5).

[0019] Preferably, during the preparation of the polar layer, the weight ratio of the polar material, the non-polar material and the malic anhydride is 100:(5-15):(0.5-2.0).

[0020] Preferably, during the preparation of the non-polar layer, the weight ratio of the polar material, the non-polar material, and the malic anhydride is 5-20:100:(0.5-2.0). Reasonable adjustment of the proportion of each component is conducive to improving the bonding strength between the film layers of the composite film.

[0021] Preferably, the coextrusion is carried out in an extruder, in which the components can be premixed, melt-treated and homogenized.

[0022] The second aspect of the present invention provides the application of the method for preparing a composite film by co-extrusion of polar materials and non-polar materials in the field of packaging.

[0023] Preferably, the application includes application in the field of food packaging.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] The present invention premixes different polar polymer materials (polar materials and non-polar materials), adds a specific cross-linking agent (malic anhydride), and causes a chemical reaction at a specific temperature and pressure (130-280°C, 100-200 atmospheres, and the specific temperature and pressure are conducive to the modification) to modify the polar materials and the non-polar materials, and then obtains the composite film by a co-extrusion method, thereby achieving one-time production of the composite film without the need to use a coating or an adhesive, simplifying the production process, reducing the production cost, and achieving the purpose of strong bonding between film layers of the composite film. DETAILED DESCRIPTION

[0026] In order to make the technical scheme of the present invention more clearly understood by those skilled in the art, the following embodiments are listed for illustration. It should be pointed out that the following embodiments do not limit the protection scope of the present invention.

[0027] Unless otherwise specified, the raw materials, reagents or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods.

[0028] The dehydrated malic anhydride used in the following examples can be provided by Shandong Jinan Aoxing Chemical Co., Ltd., and PA can be provided by Jiangsu Haiyang Chemical Fiber or Hengkun Group.

[0029] Example 1: Method for preparing composite film by coextrusion of polar material and non-polar material

[0030] The method for preparing a composite film by coextrusion of a polar material and a non-polar material comprises the following steps:

[0031] Preparation of polar layer: In a double-die extruder, 100 parts by weight of PA, 6 parts by weight of HDPE, and 1 part by weight of dehydrated malic anhydride are premixed, melt-treated (the temperature of the melt treatment is 240° C., the pressure is 145 atmospheres, and the melt treatment time is 10 seconds), and homogenized (the homogenization treatment is a conventional process in the art, and the homogenization treatment time is 4 seconds), the melt treatment temperature is 265° C., and the pressure is 180 atmospheres;

[0032] Preparation of the non-polar layer: In a dual-die extruder, 100 parts by weight of HDPE, 6 parts by weight of PA, and 1 part by weight of dehydrated malic anhydride were premixed, melt-treated (the temperature of the melt treatment was 220° C., the pressure was 135 atmospheres, and the time of the melt treatment was 10 seconds), and homogenized. The co-extrusion process included melt treatment, and the melt treatment temperature was 265° C. and the pressure was 180 atmospheres.

[0033] The polar layer and the non-polar layer are compounded by extrusion after homogenization treatment, cast on a cooling wheel until the temperature drops to 20°C, and then rolled up to obtain a composite film.

[0034] Example 2: Method for preparing composite film by coextrusion of polar material and non-polar material

[0035] The method for preparing a composite film by coextrusion of a polar material and a non-polar material comprises the following steps:

[0036] Preparation of polar layer: In a double-die extruder, 100 parts by weight of PA, 9 parts by weight of PP, and 0.5 parts by weight of dehydrated malic anhydride were premixed, melt-treated (the temperature of the melt treatment was 270° C., the pressure was 170 atmospheres, and the melt treatment time was 8 seconds), and homogenized, and the melt treatment temperature was 260° C. and the pressure was 180 atmospheres;

[0037] Preparation of the non-polar layer: In a double-die extruder, 100 parts by weight of PP, 8 parts by weight of PA, and 1 part by weight of dehydrated malic anhydride were premixed, melt-treated (the temperature of the melt treatment was 250° C., the pressure was 165 atmospheres, and the time of the melt treatment was 8 seconds), and homogenized. The co-extrusion process included melt treatment, and the melt treatment temperature was 260° C. and the pressure was 180 atmospheres.

[0038] The polar layer and the non-polar layer are compounded by extrusion after homogenization treatment, cast on a cooling wheel until the temperature drops to 20°C, and then rolled up to obtain a composite film.

[0039] Example 3: Method for preparing composite film by coextrusion of polar material and non-polar material

[0040] The method for preparing a composite film by coextrusion of a polar material and a non-polar material comprises the following steps:

[0041] Preparation of polar layer: In a double-die extruder, 100 parts by weight of PET, 5 parts by weight of HDPE, and 1.2 parts by weight of dehydrated malic anhydride were premixed, melt-treated (the temperature of the melt treatment was 270° C., the pressure was 160 atmospheres, and the melt treatment time was 7 seconds), and homogenized;

[0042] Preparation of the non-polar layer: In a dual-die extruder, 100 parts by weight of HDPE, 7 parts by weight of PET, and 1.2 parts by weight of dehydrated malic anhydride were premixed, melt-treated, and homogenized. The coextrusion process included melt treatment (the melt treatment temperature was 250° C., the pressure was 165 atmospheres, and the melt treatment time was 7 seconds);

[0043] The polar layer and the non-polar layer are compounded by extrusion after homogenization treatment, cast on a cooling wheel until the temperature drops to 20°C, and then rolled up to obtain a composite film.

[0044] Example 4: Method for preparing composite film by coextrusion of polar material and non-polar material

[0045] The method for preparing a composite film by coextrusion of a polar material and a non-polar material comprises the following steps:

[0046] Preparation of polar layer: In a double-die extruder, 100 parts by weight of PET, 8 parts by weight of PP, and 0.8 parts by weight of dehydrated malic anhydride were premixed, melt-treated, and homogenized. The melting temperature was 265° C., the pressure was 170 atmospheres, and the melting time was 7 seconds.

[0047] Preparation of the non-polar layer: In a double-die extruder, 100 parts by weight of PP, 8 parts by weight of PET, and 0.8 parts by weight of dehydrated malic anhydride are premixed, melt-treated, and homogenized. The coextrusion process includes melt treatment at a temperature of 275° C., a pressure of 180 atmospheres, and a melt treatment time of 7 seconds.

[0048] The polar layer and the non-polar layer are compounded by extrusion after homogenization treatment, cast on a cooling wheel until the temperature drops to room temperature 25°C, and then rolled up to obtain a composite film.

[0049] Example 5: Method for preparing composite film by coextrusion of polar material and non-polar material

[0050] The method for preparing a composite film by coextrusion of a polar material and a non-polar material comprises the following steps:

[0051] Preparation of polar layer: In a double-die extruder, 100 parts by weight of PBT, 7 parts by weight of HDPE, and 1.1 parts by weight of dehydrated malic anhydride were premixed, melt-treated, and homogenized. The melting temperature was 230° C., the pressure was 150 atmospheres, and the melting time was 6 seconds.

[0052] Preparation of the non-polar layer: In a double-die extruder, 100 parts by weight of HDPE, 7 parts by weight of PBT, and 1.1 parts by weight of dehydrated malic anhydride are premixed, melt-treated, and homogenized. The coextrusion process includes melt treatment at a temperature of 240° C., a pressure of 150 atmospheres, and a melt treatment time of 6 seconds.

[0053] The polar layer and the non-polar layer are compounded by extrusion after homogenization treatment, cast on a cooling wheel until the temperature drops to room temperature 15°C, and then rolled up to obtain a composite film.

[0054] Example 6: Method for preparing composite film by coextrusion of polar material and non-polar material

[0055] A method for preparing a composite film by coextrusion of a polar material and a non-polar material comprises the following steps:

[0056] Preparation of polar layer: In a double-die extruder, 100 parts by weight of PBT, 10 parts by weight of PP, and 1 part by weight of dehydrated malic anhydride were premixed, melt-treated, and homogenized. The melting temperature was 215° C., the pressure was 160 atmospheres, and the melting time was 8 seconds.

[0057] Preparation of the non-polar layer: In a double-die extruder, 100 parts by weight of PP, 10 parts by weight of PBT, and 1 part by weight of dehydrated malic anhydride are premixed, melt-treated, and homogenized. The coextrusion process includes melt treatment at a temperature of 265° C., a pressure of 180 atmospheres, and a melt treatment time of 7 seconds.

[0058] The polar layer and the non-polar layer are compounded by extrusion after homogenization treatment, cast on a cooling wheel until the temperature drops to 20°C, and then rolled up to obtain a composite film.

[0059] Example 7: Method for preparing composite film by coextrusion of polar material and non-polar material

[0060] The method for preparing a composite film by coextrusion of a polar material and a non-polar material comprises the following steps:

[0061] Preparation of polar layer: In a double-die extruder, 100 parts by weight of EVOH, 15 parts by weight of HDPE, and 2 parts by weight of dehydrated malic anhydride were premixed, melt-treated, and homogenized. The melting temperature was 175° C., the pressure was 130 atmospheres, and the melting time was 8 seconds.

[0062] Preparation of the non-polar layer: In a double-die extruder, 100 parts by weight of HDPE, 15 parts by weight of EVOH, and 2 parts by weight of dehydrated malic anhydride are premixed, melt-treated, and homogenized. The coextrusion process includes melt treatment at a temperature of 165° C., a pressure of 135 atmospheres, and a melt treatment time of 8 seconds.

[0063] The polar layer and the non-polar layer are compounded by extrusion after homogenization treatment, cast on a cooling wheel until the temperature drops to 20°C, and then rolled up to obtain a composite film.

[0064] Example 8: Method for preparing composite film by coextrusion of polar material and non-polar material

[0065] The method for preparing a composite film by coextrusion of a polar material and a non-polar material comprises the following steps:

[0066] Preparation of polar layer: In a double-die extruder, 100 parts by weight of EVOH, 10 parts by weight of PP, and 1.8 parts by weight of dehydrated malic anhydride were premixed, melt-treated, and homogenized. The melting temperature was 200° C., the pressure was 150 atmospheres, and the melting time was 8 seconds.

[0067] Preparation of the non-polar layer: In a double-die extruder, 100 parts by weight of PP, 10 parts by weight of EVOH, and 1.8 parts by weight of dehydrated malic anhydride are premixed, melt-treated, and homogenized. The coextrusion process includes melt treatment at a temperature of 205° C., a pressure of 150 atmospheres, and a melt treatment time of 8 seconds.

[0068] The polar layer and the non-polar layer are compounded by extrusion after homogenization treatment, cast on a cooling wheel until the temperature drops to 20°C, and then rolled up to obtain a composite film.

[0069] Comparative Example 1

[0070] Compared with Example 1, in Comparative Example 1, an equal amount of DCP (dicumyl peroxide) is used as a cross-linking agent to replace the dehydrated malic anhydride in Example 1, and the rest of the process is the same as in Example 1.

[0071] Comparative Example 2

[0072] Compared with Example 8, the temperature of the melt treatment in Comparative Example 2 is 120°C, and the rest of the process is the same as that of Example 8.

[0073] Product effect testing

[0074] The composite films prepared in Examples 1-8 and Comparative Examples 1-2 were taken. After the composite films were attached using a 3M600 standard tape (length of 200 mm), they were rolled back and forth 6 times at 100 mm / min using a 2 kg standard pressing wheel, and then peeled off within 0.5 s in a 160° direction. The maximum number of peeling times at which the composite films did not delaminate was recorded. The results are shown in Table 1.

[0075] Table 1

[0076]

[0077] It can be seen from Table 1 that the number of times the composite films prepared in Examples 1-8 of the present invention resist peeling is significantly higher than that of the composite films prepared in Comparative Examples 1-2, indicating that the composite films prepared by the method described in the present invention have strong bonding strength between the film layers.

[0078] From the results of Example 8 and Comparative Example 2 in Table 1, it can be seen that the temperature of the melt treatment has a significant effect on the bonding strength of the composite film obtained. From the results of Example 1 and Comparative Example 1 in Table 1, it can be seen that the type of cross-linking agent selected has a significant effect on the bonding strength of the composite film obtained.

[0079] The composite film prepared by the method of the present invention does not require the use of a coating or an adhesive, and can achieve one-time production of the composite film, thereby simplifying the production process, reducing the production cost, and the film layers of the composite film have strong bonding strength.

Claims

1. A method for preparing a composite film by coextrusion of polar materials and non-polar materials, characterized in that: The following steps are involved: Premixing polar materials, non-polar materials and malic anhydride, and then co-extruding to obtain a composite film; the co-extrusion process includes a melt treatment, the melt treatment temperature is 130-280° C., and the pressure is 100-200 atmospheres; The polar material is selected from at least one of polyethylene terephthalate, polybutylene terephthalate, nylon, and ethylene-vinyl alcohol copolymer; The non-polar material is selected from at least one of polypropylene and polyethylene; The composite membrane comprises a polar layer and a non-polar layer; Preparation of the polar layer: premixing polar material, non-polar material and malic anhydride, and then co-extruding; Preparation of the non-polar layer: premixing polar material, non-polar material and malic anhydride, and then co-extruding; During the preparation of the polar layer, the weight ratio of the polar material, the non-polar material, and the malic anhydride is 100:(3-25):(0.2-2.5); During the preparation of the non-polar layer, the weight ratio of the polar material, the non-polar material and the malic anhydride is 3-25:100:(0.2-2.5).

2. The method according to claim 1, characterized in that The temperature of the melt treatment is 135-255° C., and the pressure is 110-180 atmospheres.

3. The method according to claim 1, characterized in that During the preparation of the polar layer, the weight ratio of the polar material, the non-polar material and the malic anhydride is 100:(5-15):(0.5-2.0).

4. The method according to claim 1, characterized in that: During the preparation of the non-polar layer, the weight ratio of the polar material, the non-polar material and the malic anhydride is 5-20:100:(0.5-2.0).

5. The method according to claim 1, characterized in that The coextrusion is carried out in an extruder, in which the components can be premixed, melt-treated and homogenized.

6. Use of the method according to any one of claims 1 to 5 in the field of packaging.

7. The use according to claim 6, characterized in that: Said applications include applications in the field of food packaging.

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