Three-layer co-extrusion two-way stretch film and preparation process thereof

Abstract

The invention provides a three-layer co-extrusion two-way stretch film and a preparation process, the three-layer co-extrusion two-way stretch film adopts a multi-layer co-extrusion structure, the three-layer co-extrusion two-way stretch film comprises a film body, the film body comprises an upper surface layer, a core layer and a lower surface layer, and the upper surface layer and the lower surface layer are anti-adhesion layers. The upper surface layer and the lower surface layer comprise the following components in parts by weight: 80-97 parts of high-density polyethylene, 1-10 parts of anti-adhesion master batch and 2-10 parts of liquid crystal pigment powder; wherein the melt index of the high density polyethylene is 0.5 to 3 g / 10 min; the core layer comprises the following components in parts by weight: 80-97 parts of high-density polyethylene, 1-10 parts of antistatic master batch and 2-10 parts of liquid crystal pigment powder, and the melt index of the high-density polyethylene is 0.5-3g / 10min. The thin film is made of a single material and is convenient to recycle and reuse, meanwhile, the color of the thin film can be changed along with the change of an observation angle, and the thin film has a certain barrier property and an anti-counterfeiting effect.

Description

Technical Field

[0001] The present disclosure relates to the technical field of composite films, and specifically, to a three-layer co-extruded biaxially oriented film and a preparation process thereof. Background Art

[0002] At present, the pearlescent films on the market are mainly made of polypropylene (PP) resin as raw material, adding inorganic fillers such as calcium carbonate and pearlescent pigments and then biaxially oriented to form a pearlescent effect. In the production process, various additives are usually made into a pearlescent masterbatch with carrier PP, and then added to the production line in the form of masterbatch to prepare BOPP pearlescent film, which can be widely used in the direct packaging of dried fruits, ice creams, candies, high-grade soaps, gifts, etc. However, the waste roll films after use cannot be recycled, causing great environmental pollution and not meeting the requirements of sustainable development. In addition, the anti-counterfeiting effect of the existing pearlescent films is not obvious enough. Summary of the Invention

[0003] The purpose of the embodiments of the present disclosure is to provide a three-layer co-extruded biaxially oriented film and a preparation process thereof to solve the above problems existing in the prior art.

[0004] To solve the above technical problems, on the one hand, an embodiment of the present disclosure provides a three-layer co-extruded biaxially oriented film, which adopts a multi-layer co-extrusion structure and includes a film body. The film body includes an upper surface layer, a core layer, and a lower surface layer. The upper surface layer and the lower surface layer are anti-blocking layers. The upper surface layer and the lower surface layer include components in the following weight ratio: 80-97 parts of high-density polyethylene, 1-10 parts of anti-blocking masterbatch, and 2-10 parts of liquid crystal pigment powder; wherein, the melt index of the high-density polyethylene is 0.5-3 g / 10 min; the core layer includes components in the following weight ratio: 80-97 parts of high-density polyethylene, 1-10 parts of antistatic masterbatch, and 2-10 parts of liquid crystal pigment powder, wherein the melt index of the high-density polyethylene is 0.5-3 g / 10 min.

[0005] In some embodiments, the anti-blocking masterbatch includes siloxane and isotactic polypropylene, wherein the mass of siloxane accounts for 20-30% of the total mass of the anti-blocking masterbatch.

[0006] In some embodiments, the siloxane can be in the form of organic particles, and the particle size of the siloxane particles is 1-2 μm.

[0007] In some embodiments, the antistatic masterbatch includes 75-85 parts by weight of isotactic homopolypropylene and 15-25 parts by weight of a migrating antistatic agent.

[0008] In some embodiments, the migratory antistatic agent comprises 50 to 60 parts by weight of polypropylene, 20 to 25 parts by weight of ethoxyamine, and 20 to 25 parts by weight of glycerol monostearate.

[0009] In some embodiments, the component ratios of the upper surface layer and the lower surface layer are different.

[0010] In some embodiments, the thickness of the film body is 25 - 35 μm, the thickness of the upper surface layer and the lower surface layer is 7 - 10 μm, and the thickness of the core layer is 10 - 15 μm.

[0011] An embodiment of the present disclosure provides a preparation process for a three - layer co - extrusion biaxially stretched film. The three - layer co - extrusion biaxially stretched film is the three - layer co - extrusion biaxially stretched film described in any one of the above, and the preparation process includes the following steps:

[0012] Uniformly mix the raw materials of each component in each layer, then perform melt co - extrusion and cooling to form a thick sheet;

[0013] Pass the formed thick sheet through a longitudinal stretching device and a transverse stretching device in sequence to perform a biaxial stretching process to generate the film body:

[0014] Perform corona treatment on the stretched film to increase the surface tension;

[0015] Wind the film body after corona treatment into a master roll for aging treatment;

[0016] Cut the film after aging treatment into products according to requirements.

[0017] In some embodiments, the step of uniformly mixing the raw materials of each component in each layer, then performing melt co - extrusion and cooling to form a thick sheet includes:

[0018] Extrude the lower surface layer through a first auxiliary extruder, and its outlet temperature is 245 - 250 °C; extrude the core layer through a main extruder, and its outlet temperature is 245 - 250 °C; extrude the upper surface layer through a second auxiliary extruder, and its outlet temperature is 245 - 250 °C and the die head temperature is 245 - 250 °C; the temperature of the cooling casting sheet device for cooling is controlled at 75 - 80 °C.

[0019] In some embodiments, the step of passing the formed thick sheet through a longitudinal stretching device and a transverse stretching device in sequence to perform a biaxial stretching process to generate the film body includes:

[0020] The operating temperature of the rollers in the longitudinal stretching device is controlled as follows: the preheating zone is 85 - 90 °C, the stretching zone is 110 - 115 °C, and the shaping zone is 90 - 95 °C, where the stretching ratio is 4.5 - 5.5; the operating temperature of the rollers in the transverse stretching device is controlled as follows: the preheating zone is 150 - 155 °C, the stretching zone is 125 - 130 °C, and the shaping zone is 95 - 100 °C, where the stretching ratio is 6 - 8.

[0021] The film of the embodiment of the present disclosure uses a single material, which is convenient for recycling. At the same time, the color of the film can change with the viewing angle, and it has certain barrier properties and anti-counterfeiting effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings described below are only some embodiments recorded in the present disclosure. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0023] Figure 1 It is a schematic structural diagram of a three-layer coextruded biaxially stretched film in the embodiment of the present disclosure. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] Reference is made herein to the various aspects and features of the present disclosure with reference to the drawings.

[0025] It should be understood that various modifications can be made to the embodiments applied herein. Therefore, the above description should not be regarded as a limitation, but only as an example of the embodiments. Those skilled in the art will think of other modifications within the scope and spirit of the present disclosure.

[0026] The drawings included in the specification and forming a part of the specification illustrate the embodiments of the present disclosure, and together with the general description of the present disclosure given above and the detailed description of the embodiments given below, are used to explain the principles of the present disclosure.

[0027] These and other features of the present disclosure will become apparent from the following description of the preferred forms of the embodiments given by way of non-limiting example with reference to the drawings.

[0028] It should also be understood that although the present disclosure has been described with reference to some specific examples, those skilled in the art can surely implement many other equivalent forms of the present disclosure, which have the features as described in the claims and thus are all within the protection scope defined hereby.

[0029] When combined with the drawings, the above and other aspects, features, and advantages of the present disclosure will become more apparent in view of the following detailed description.

[0030] Specific embodiments of the present disclosure will hereinafter be described with reference to the accompanying drawings; however, it should be understood that the embodiments claimed are merely examples of the present disclosure, which can be implemented in various ways. Well-known and / or repetitive functions and structures are not described in detail to avoid obscuring the present disclosure with unnecessary or redundant details. Therefore, the specific structural and functional details claimed herein are not intended to be limiting, but are merely a basis and representative basis for the claims to teach those skilled in the art to make any suitable combination substantially.

[0031] The first embodiment of the present disclosure provides a three-layer co-extruded biaxially oriented film, which adopts a multi-layer co-extrusion structure and includes a film body. The thickness of the film body is 25-35 μm. The film body includes an upper surface layer 1, a core layer 2, and a lower surface layer 3. Among them, the thicknesses of the upper surface layer 1 and the lower surface layer 3 are 7-10 μm. Here, the thickness of the lower surface layer 3 can be greater than that of the upper surface layer 1, and the thickness of the core layer 2 is 10-15 μm.

[0032] Specifically, the upper surface layer 1 and the lower surface layer 3 are anti-blocking layers. The upper surface layer 1 and the lower surface layer 3 include the following components in parts by weight: 80-97 parts of high-density polyethylene, 1-10 parts of anti-blocking masterbatch, and 2-10 parts of liquid crystal pigment powder; among them, the melt index of the high-density polyethylene is 0.5-3 g / 10 min (190 °C, 2.16 Kg). Here, the component ratios of the upper surface layer 1 and the lower surface layer 3 can be different.

[0033] Further, the anti-blocking masterbatch includes siloxane and isotactic polypropylene. Among them, the mass of siloxane accounts for 20-30% of the total mass of the anti-blocking masterbatch. The siloxane can be in the form of organic particles, and the particle size of the siloxane particles is 1-2 μm.

[0034] Further, the core layer 2 includes the following components in parts by weight: 80-97 parts of high-density polyethylene, 1-10 parts of antistatic masterbatch, and 2-10 parts of liquid crystal pigment powder, where the melt index of the high-density polyethylene is 0.5-3 g / 10 min (190 °C, 2.16 Kg).

[0035] Further, the antistatic masterbatch includes 75-85 parts by weight of isotactic homopolypropylene and 15-25 parts by weight of migrating antistatic agent. Here, the migrating antistatic agent includes 50-60 parts by weight of polypropylene, 20-25 parts by weight of ethoxyamine, and 20-25 parts by weight of glycerol monostearate.

[0036] In a specific embodiment, the main components of the upper surface layer 1 include 85 parts of high-density polyethylene, 8 parts of anti-blocking masterbatch, and 7 parts of liquid crystal pigment powder. Among them, the anti-blocking masterbatch includes silicone and isotactic polypropylene, and the mass of the silicone accounts for 30% of the total mass of the anti-blocking masterbatch; the main components of the lower surface layer 3 include 90 parts of high-density polyethylene, 5 parts of anti-blocking masterbatch, and 5 parts of liquid crystal pigment powder. The anti-blocking masterbatch includes silicone and isotactic polypropylene, and the mass of the silicone accounts for 20% of the total mass of the anti-blocking masterbatch.

[0037] The core layer 2 specifically includes 90 parts of high-density polyethylene, 2 parts of antistatic masterbatch, and 8 parts of liquid crystal pigment powder. Among them, the antistatic masterbatch includes 80 parts by weight of isotactic homopolypropylene and 20 parts by weight of migrating antistatic agent. The components of the migrating antistatic agent include 56 parts by weight of polypropylene, 22 parts by weight of ethoxyamine, and 22 parts by weight of glycerol monostearate.

[0038] The film of the embodiment of the present disclosure uses a single material, which is convenient for recycling. All three layers of the film are HDPE and can be 100% recycled. Through processes such as crushing, cleaning, and granulation, it can ultimately be used in aspects such as composite wood, plastic wood, and toys. The recovery rate of HDPE is second only to PET, and most recycling centers around the world accept HDPE for recycling. At the same time, the color of the film can change with the viewing angle. The principle of angle-dependent color change of the film depends on the different scattering and reflection modes of the liquid crystal pigment powder for incident light, resulting in the film showing different colors when observed from different angles, having certain barrier properties and anti-counterfeiting effects. Compared with the inorganic fillers of the existing pearlescent film, the liquid crystal pigment powder is an organic substance and can be well integrated with polypropylene.

[0039] The second embodiment of the present disclosure provides a preparation process for a three-layer co-extruded biaxially oriented film, which includes the three-layer co-extruded biaxially oriented film of any one of the above first embodiments. The preparation process of the three-layer co-extruded biaxially oriented film here includes the following steps:

[0040] S101, uniformly mix the raw materials of each component in the above layers, then perform melt co-extrusion and cooling to form a thick sheet; specifically, extrude the lower surface layer 3 through the first auxiliary extruder, and its outlet temperature is 245 - 250 °C; extrude the core layer 2 through the main extruder, and its outlet temperature is 245 - 250 °C; extrude the upper surface layer 1 through the second auxiliary extruder, and its outlet temperature is 245 - 250 °C and the die head temperature is 245 - 250 °C; in addition, the temperature of the cooling casting device for cooling is controlled at 75 - 80 °C;

[0041] S102. The thick sheet formed in step S101 is successively passed through a machine direction orientation (MDO) device and a transverse direction orientation (TDO) device to perform a biaxial stretching process to generate the film body:

[0042] Among them, the operating temperature of the rollers in the longitudinal stretching device is controlled as follows: the preheating zone is 85 - 90 °C, the stretching zone is 110 - 115 °C, and the shaping zone is 90 - 95 °C. Among them, the stretching ratio is 4.5 - 5.5; the operating temperature of the rollers in the transverse stretching device is controlled as follows: the preheating zone is 150 - 155 °C, the stretching zone is 125 - 130 °C, and the shaping zone is 95 - 100 °C. Among them, the stretching ratio is 6 - 8;

[0043] Step S103. The film stretched in the above step S102 is subjected to corona treatment to increase the surface tension;

[0044] Step S104. The film body processed in the above step S103 is wound into a master roll for aging treatment;

[0045] Step S105. The film processed in the above step S104 is slit into products according to requirements.

[0046] The film of the embodiment of the present disclosure uses a single material, which is convenient for recycling. At the same time, the color of the film can change with the change of the viewing angle, and has certain barrier properties and anti-counterfeiting effects.

[0047] In addition, the features of the embodiments shown in the drawings of the present application or various embodiments mentioned in this specification do not have to be understood as independent embodiments of each other. Instead, each feature described in one example of one embodiment can be combined with one or more other desired features from other embodiments, thereby generating other embodiments not described in words or with reference to the drawings.

[0048] The above-described embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A three-layer co-extruded biaxially oriented film, characterized in that: A multi-layer co-extrusion structure is adopted, which includes a film body, and the film body includes an upper surface layer, a core layer and a lower surface layer. The upper surface layer and the lower surface layer are anti-adhesion layers, and the upper surface layer and the lower surface layer include components in the following weight ratio: 80-97 parts of high-density polyethylene, 1-10 parts of anti-adhesion masterbatch and 2-10 parts of liquid crystal pigment powder; wherein the melt index of the high-density polyethylene is 0.5-3g / 10min; the core layer includes components in the following weight ratio: 80-97 parts of high-density polyethylene, 1-10 parts of antistatic masterbatch and 2-10 parts of liquid crystal pigment powder, wherein the melt index of the high-density polyethylene is 0.5-3g / 10min.

2. The three-layer co-extruded biaxially oriented film according to claim 1, characterized in that: The anti-adhesion masterbatch comprises siloxane and isotactic polypropylene, wherein the mass of siloxane accounts for 20-30% of the total mass of the anti-adhesion masterbatch.

3. The three-layer co-extruded biaxially oriented film according to claim 2, characterized in that: The siloxane may be in the form of organic particles, and the particle size of the siloxane particles is 1 to 2 μm.

4. The three-layer co-extruded biaxially oriented film according to claim 1, characterized in that: The antistatic masterbatch comprises 75 to 85 parts by weight of isotactic homopolypropylene and 15 to 25 parts by weight of a migratory antistatic agent.

5. The three-layer co-extruded biaxially oriented film according to claim 4, characterized in that: The migratory antistatic agent comprises 50 to 60 parts by weight of polypropylene, 20 to 25 parts by weight of ethoxylated amine and 20 to 25 parts by weight of glycerol monostearate.

6. The three-layer co-extruded biaxially oriented film according to claim 1, characterized in that: The upper surface layer and the lower surface layer have different component ratios.

7. The three-layer co-extruded biaxially oriented film according to claim 1, characterized in that: The thickness of the film body is 25-35 μm, the thickness of the upper surface layer and the lower surface layer is 7-10 μm, and the thickness of the core layer is 10-15 μm.

8. A process for preparing a three-layer co-extruded biaxially oriented film, characterized in that: The three-layer co-extruded biaxially oriented film is a three-layer co-extruded biaxially oriented film according to any one of claims 1 to 7, and the preparation process comprises the following steps: The raw materials of each component in each layer are uniformly mixed, melt co-extruded and cooled to form a thick sheet; The formed thick sheet is sequentially passed through a longitudinal stretching device and a transverse stretching device to perform a biaxial stretching process to generate the film body: The stretched film is subjected to corona treatment to increase the surface tension; The corona treated film is wound into a mother roll for aging treatment; The film after aging treatment is cut into products according to demand.

9. The process for preparing a three-layer co-extruded biaxially oriented film according to claim 8, characterized in that: The process of uniformly mixing the raw materials of the components in each layer, performing melt co-extrusion and cooling to form a thick sheet comprises: The lower surface layer is extruded by the first auxiliary extruder, and its outlet temperature is 245-250°C; the core layer is extruded by the main extruder, and its outlet temperature is 245-250°C; the upper surface layer is extruded by the second auxiliary extruder, and its outlet temperature is 245-250°C and the die head temperature is 245-250°C; the temperature of the cooling casting device used for cooling is controlled at 75-80°C.

10. The process for preparing a three-layer co-extruded biaxially oriented film according to claim 8, characterized in that: The process of sequentially passing the formed thick sheet through a longitudinal stretching device and a transverse stretching device to perform a biaxial stretching process to generate the film body comprises: The operating temperature of the rollers in the longitudinal stretching device is controlled as follows: the preheating zone is 85-90°C, the stretching zone is 110-115°C, and the shaping zone is 90-95°C, wherein the stretching ratio is 4.5-5.5; the operating temperature of the rollers in the transverse stretching device is controlled as follows: the preheating zone is 150-155°C, the stretching zone is 125-130°C, and the shaping zone is 95-100°C, wherein the stretching ratio is 6-8.

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