Non-transparent high-barrier polypropylene composite film

Abstract

The invention relates to an opaque high-barrier polypropylene composite film. The packaging film comprises a polypropylene layer, a barrier layer and a heat sealing layer, the polypropylene layer is a biaxially oriented polypropylene film, the polypropylene layer is made of an antistatic polypropylene material, the barrier layer is an aluminized casting polypropylene film, the heat sealing layer is a homo-polypropylene film, a first adhesive layer is arranged between the polypropylene layer and the barrier layer, and a second adhesive layer is arranged between the polypropylene layer and the barrier layer. And a second adhesive layer is arranged between the blocking layer and the heat sealing layer. Through the technical scheme, the polypropylene film has excellent barrier property, good opaqueness and other comprehensive properties meeting actual packaging requirements, so that the defects of the existing polypropylene film in related applications are overcome, and the application range of the polypropylene film in the high-requirement packaging field is expanded.

Description

Technical Field

[0001] The invention relates to a packaging film, in particular to an opaque high-barrier polypropylene composite film. Background Art

[0002] In the modern packaging industry, polypropylene film is widely used because of its good mechanical properties, chemical stability, processing performance and relatively low cost. However, ordinary polypropylene film has certain limitations in terms of barrier properties, especially the barrier effect on small molecules such as oxygen and water vapor, which is difficult to meet the packaging needs of some products with high requirements for freshness and moisture resistance. At the same time, for some products that need to be stored away from light, such as medicines and certain food additives, transparent polypropylene film cannot provide effective light protection, which can easily lead to product deterioration and degradation due to light.

[0003] At present, although there are some methods to improve the barrier properties of polypropylene films, such as using multi-layer composite structures or adding barrier fillers, there are still many challenges in achieving high barrier properties while taking into account the balance of opacity and comprehensive performance. For example, some high-barrier composite structures may lead to reduced film flexibility, increased processing difficulty, or inability to effectively control costs while ensuring opacity. Therefore, it is of great practical significance to develop a polypropylene composite film that can meet high barrier requirements, have good opacity and excellent comprehensive performance. Summary of the invention

[0004] The invention provides an opaque high-barrier polypropylene composite film, which solves the problem in the prior art that it is difficult for the composite film to ensure a balanced comprehensive performance while taking into account both high barrier and opacity.

[0005] The above technical problems of the present invention are mainly solved by the following technical solutions: an opaque high-barrier polypropylene composite film, comprising a polypropylene layer, a barrier layer and a heat-sealing layer, the polypropylene layer is a biaxially oriented polypropylene film, the material of the polypropylene layer is an antistatic polypropylene material, the barrier layer is an aluminum-plated cast polypropylene film, the heat-sealing layer is a homopolymer polypropylene film, a first adhesive layer is provided between the polypropylene layer and the barrier layer, and a second adhesive layer is provided between the barrier layer and the heat-sealing layer.

[0006] In the present invention, the polypropylene layer is made of antistatic polypropylene material, and the surface resistance can be controlled within 10 8 ~10 11Ω. Surface resistivity is an important data to characterize the electrical properties of dielectric or insulating materials. It represents the resistance of each square area of ​​dielectric surface to the surface leakage current between the two opposite sides of the square. The smaller the surface resistivity, the better the conductivity of the material surface, which can more effectively conduct static electricity, thus having better anti-static performance. 6 Ω to 10 9 Materials between Ω are considered to be good anti-static materials, while resistance values ​​greater than 10 12 Ω is considered an insulating material and is prone to accumulate static electricity. The surface resistance of antistatic polypropylene is much less than 10 12 Ω, closer to 10 6 Ω to 10 9 Ω, so it has a relatively good antistatic effect, which can effectively prevent the composite film from absorbing dust, impurities due to static electricity during packaging, transportation and use.

[0007] The specific material of the aluminum-coated cast polypropylene film can be reinforced vacuum aluminum-coated cast polypropylene. The aluminum-coated cast polypropylene film used in the present invention has certain requirements for its flatness, requiring its thickness deviation value to be less than 2%. The aluminum-coated cast polypropylene film is used as a barrier layer, and its oxygen barrier performance is less than 20, and its water barrier performance is less than 0.5.

[0008] The heat-sealing layer composed of homopolymer polypropylene provides basic mechanical strength and structural stability for the entire composite film, ensuring that the film can maintain its intact shape during processing and use, and has high tensile strength and tear resistance. For example, the tensile strength can reach 30 to 50 MPa, and the tear strength is between 100 and 200 N / mm.

[0009] In summary, the present invention achieves light-proof and high barrier effects by introducing aluminum-plated cast polypropylene film, so that the overall water barrier performance is less than 0.5, and under the joint barrier of the propylene layer and the heat-sealing layer, the overall oxygen barrier performance is less than 3; at the same time, the propylene layer selected as antistatic polypropylene material also makes the whole have a good antistatic effect; the heat-sealing layer composed of homopolymer polypropylene provides basic mechanical strength and structural stability for the entire composite film. Therefore, the present invention ensures the overall comprehensive performance balance while taking into account the high barrier and opaque characteristics.

[0010] Furthermore, the surface layer of the polypropylene layer is also coated with a coating layer, and the coating layer is composed of modified polyvinyl alcohol resin, polyurethane resin and ethyl ester. The coating layer has a good printing effect, so the present invention can directly perform surface printing by setting the coating layer, and the coating layer can also further improve the overall oxygen barrier performance of the present invention, and achieve an oxygen barrier performance of less than 0.8.

[0011] Furthermore, in order to control the overall thickness of the composite film within a more reasonable range, the thickness of the coating layer is between 1 and 1.5 μm, the thickness of the polypropylene layer is between 10 and 30 μm, the thickness of the barrier layer is between 10 and 30 μm, and the thickness of the heat-sealing layer is between 20 and 50 μm, so as to ensure that the overall flexibility of the composite film meets the standard.

[0012] Therefore, compared with the prior art, the present invention has the following characteristics: 1. The present invention achieves light-proof and high barrier effects by introducing an aluminum-plated cast polypropylene film, so that the overall water barrier performance is less than 0.5, and under the joint barrier of the propylene layer and the heat-sealing layer, the overall oxygen barrier performance is less than 3; 2. The propylene layer is selected from antistatic polypropylene material, which also enables the overall antistatic effect; 3. The heat-sealing layer composed of homopolymer polypropylene provides basic mechanical strength and structural stability for the entire composite film. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Attached Figure 1 It is a structural schematic diagram of the present invention. DETAILED DESCRIPTION

[0014] The technical solution of the present invention is further specifically described below through embodiments and in conjunction with the accompanying drawings.

[0015] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0016] Example 1: See Figure 1 An opaque high-barrier polypropylene composite film comprises a polypropylene layer 1, a barrier layer 2 and a heat-sealing layer 3, the polypropylene layer is a biaxially oriented polypropylene film, the material of the polypropylene layer is an antistatic polypropylene material, the barrier layer is an aluminum-coated cast polypropylene film, the heat-sealing layer is a homopolymer polypropylene film, a first adhesive layer 4 is provided between the polypropylene layer and the barrier layer, and a second adhesive layer 5 is provided between the barrier layer and the heat-sealing layer.

[0017] In this embodiment, the polypropylene layer is made of antistatic polypropylene material, and the surface resistance can be controlled within 10 8 ~10 11Ω. Surface resistivity is an important data to characterize the electrical properties of dielectric or insulating materials. It represents the resistance of each square area of ​​dielectric surface to the surface leakage current between the two opposite sides of the square. The smaller the surface resistivity, the better the conductivity of the material surface, which can more effectively conduct static electricity, thus having better anti-static performance. 6 Ω to 10 9 Materials between Ω are considered to be good anti-static materials, while resistance values ​​greater than 10 12 Ω is considered an insulating material and is prone to accumulate static electricity. The surface resistance of antistatic polypropylene is much less than 10 12 Ω, closer to 10 6 Ω to 10 9 Ω, so it has a relatively good antistatic effect, which can effectively prevent the composite film from absorbing dust, impurities due to static electricity during packaging, transportation and use.

[0018] The specific material of the aluminum-coated cast polypropylene film can be reinforced vacuum aluminum-coated cast polypropylene. The aluminum-coated cast polypropylene film used in this embodiment has certain requirements for its flatness, requiring its thickness deviation value to be less than 2%. The aluminum-coated cast polypropylene film is used as a barrier layer, and its oxygen barrier performance is less than 20, and its water barrier performance is less than 0.5. The aluminum-coated cast polypropylene film in this embodiment requires the corona strength of the aluminum-coated surface to be greater than 36 dynes, and the non-aluminum-coated surface to be greater than 34 dynes, so as to achieve a stronger composite strength.

[0019] The heat-sealing layer composed of homopolymer polypropylene provides basic mechanical strength and structural stability for the entire composite film, ensuring that the film can maintain its intact shape during processing and use, and has high tensile strength and tear resistance. For example, the tensile strength can reach 30 to 50 MPa, and the tear strength is between 100 and 200 N / mm.

[0020] In summary, this embodiment achieves light-proof and high barrier effects by introducing aluminum-plated cast polypropylene film, so that the overall water barrier performance is less than 0.5, and the overall oxygen barrier performance is less than 3 under the joint barrier of the propylene layer and the heat-sealing layer; at the same time, the propylene layer selected as antistatic polypropylene material also makes the whole have a good antistatic effect; the heat-sealing layer composed of homopolymer polypropylene provides basic mechanical strength and structural stability for the entire composite film. Therefore, this embodiment ensures the overall comprehensive performance balance while taking into account the high barrier and opaque characteristics.

[0021] In the actual composite preparation process of this embodiment, especially when the barrier layer and the heat-sealing layer are composited, since the surface tension of polypropylene is small, it is necessary to set up online corona treatment to increase the composite strength. Theoretically, the composite strength is not less than 2N / 15mm.

[0022] The second adhesive layer is coated by a coating process, and the main components of the second adhesive layer are nano-silicon oxide and polyurethane adhesive; the first adhesive layer can use the same adhesive as the second adhesive layer, or can use conventional adhesive for polypropylene composite film.

[0023] Specifically, the weight ratio of the nano-silicon oxide compound to the polyurethane adhesive is 5 to 10:100.

[0024] See Figure 1 The surface of the polypropylene layer is also coated with a coating layer 6, which is composed of modified polyvinyl alcohol resin, polyurethane resin and ethyl ester. The coating layer has a good printing effect, so the present embodiment can directly perform surface printing by setting the coating layer, and the coating layer can also further improve the overall oxygen barrier performance of the present embodiment, achieving an oxygen barrier performance of less than 0.8.

[0025] Specifically, the coating layer is composed of 10-15% modified polyvinyl alcohol resin, 20-30% polyurethane resin, and 55-70% ethyl acetate in a weight ratio. In the actual preparation process, the coating layer needs to be placed in an environment of 45° C. for at least 24 hours after coating.

[0026] Specifically, in order to control the overall thickness of the composite film within a reasonable range, the thickness of the coating layer is between 1 and 1.5 μm, the thickness of the polypropylene layer is between 10 and 30 μm, the thickness of the barrier layer is between 15 and 20 μm, and the thickness of the heat sealing layer is between 20 and 50 μm, so as to ensure that the overall flexibility of the composite film meets the standard.

[0027] In the actual production process of this embodiment, an appropriate amount of lubricant, such as erucamide, can also be applied on its surface, with the added amount being 0.5% to 2% of the mass of the polypropylene layer, to improve the surface friction properties of the composite film, facilitate the winding, unwinding and packaging operations of the film, and make the surface friction coefficient between 0.2 and 0.4.

[0028] The present invention can be modified in various ways which are obvious to those skilled in the art, and such modifications are not considered to depart from the scope of the present invention. All such modifications which are obvious to those skilled in the art are intended to be included within the scope of the present claims.

Claims

1. An opaque high barrier polypropylene composite film, characterized in that: The invention comprises a polypropylene layer, a barrier layer and a heat-sealing layer, wherein the polypropylene layer is a biaxially stretched polypropylene film, the material of the polypropylene layer is an antistatic polypropylene material, the barrier layer is an aluminum-plated cast polypropylene film, the heat-sealing layer is a homopolymer polypropylene film, a first adhesive layer is arranged between the polypropylene layer and the barrier layer, and a second adhesive layer is arranged between the barrier layer and the heat-sealing layer.

2. The opaque high barrier polypropylene composite film according to claim 1, characterized in that: The second adhesive layer is applied by a coating process, and main components of the second adhesive layer are nano silicon oxide and polyurethane adhesive.

3. The opaque high barrier polypropylene composite film according to claim 2, characterized in that: The weight ratio of the nano-silicon oxide compound to the polyurethane adhesive is 5 to 10:

100.

4. The opaque high barrier polypropylene composite film according to claim 1, characterized in that: The surface layer of the polypropylene layer is further coated with a coating layer, and the coating layer is composed of modified polyvinyl alcohol resin, polyurethane resin and ethyl ester.

5. The opaque high barrier polypropylene composite film according to claim 4, characterized in that: The coating layer is composed of 10-15% of modified polyvinyl alcohol resin, 20-30% of polyurethane resin and 55-70% of ethyl ester in a weight ratio.

6. The opaque high barrier polypropylene composite film according to claim 4, characterized in that: The coating layer has a thickness of 1 to 1.5 μm.

7. The opaque high barrier polypropylene composite film according to claim 1, characterized in that: The thickness of the polypropylene layer is 10 to 30 μm.

8. The opaque high barrier polypropylene composite film according to claim 1, characterized in that: The thickness of the barrier layer is 10 to 30 μm.

9. The opaque high barrier polypropylene composite film according to claim 1, characterized in that: The thickness of the heat sealing layer is 20-50 μm.

Images