Cover film with high flatness

Abstract

The invention discloses a high-flatness cover film, which comprises an ink layer, a PET layer, a paper layer, a polyethylene lamination layer, a barrier layer and a high-flatness particle heat sealing layer, the paper layer is kraft paper with high flatness and wrinkle resistance, an adhesive layer is arranged between the PET layer and the paper layer, high-flatness particles are added in the polyethylene lamination layer and the high-flatness particle heat sealing layer, and the barrier layer is arranged between the polyethylene lamination layer and the high-flatness particle heat sealing layer. According to the scheme, high-flatness particles are added into the polyethylene lamination layer and the high-flatness particle heat sealing layer, molecular chain arrangement and crystallization behaviors of polymer resin in the high-flatness particles are adjusted through the high-flatness particles, the phenomenon of unevenness of the cover film caused by inconsistent molecular chain orientation or non-uniform crystallization is reduced, high-flatness kraft paper is adopted as a base material, and the heat sealing performance of the cover film is improved. And the flatness and stiffness of the cover film are enhanced while the overall strength of the cover film is enhanced.

Description

Technical Field

[0001] The invention relates to the field of cover films, and more particularly to a cover film with high flatness. Background Art

[0002] Covering films are widely used in modern industrial and agricultural production and in many commodity packaging fields. Existing covering films often have the problem of poor flatness. During the production process, due to the unevenness of raw materials, limitations of processing technology, and environmental factors, the covering film is prone to unevenness such as wrinkles and wavy shapes. This not only affects the appearance quality of the covering film and reduces the overall aesthetics of the product, but also in actual use, the uneven covering film may lead to loose fitting, affecting the effective performance of its heat preservation, moisture retention, barrier and other properties, and reducing its protective effect on the covered items or products.

[0003] In addition, for some high-precision industrial packaging or packaging applications of optical instruments and other products, the flatness of the cover film is even more important. Minor unevenness may have an adverse effect on the performance or precision of the product in the package. Therefore, the development of a cover film with high flatness has important practical significance and market demand. Summary of the invention

[0004] In view of the shortcomings of the prior art, the purpose of the invention is to provide a cover film with high flatness: to solve the problem that the cover film is not flat enough, which may lead to loose fitting, affect the effective performance of its thermal insulation, moisture retention, barrier and other properties, and reduce its protective effect on the covered items or products.

[0005] The above technical purpose of the invention is achieved through the following technical scheme: a high-flatness covering film, including an ink layer, a PET layer, a paper layer, a polyethylene coating layer, a barrier layer and a high-flatness particle heat-sealing layer, the paper layer is a kraft paper with high flatness and wrinkle resistance, an adhesive layer is arranged between the PET layer and the paper layer, and high-flatness particles are added to the polyethylene coating layer and the high-flatness particle heat-sealing layer.

[0006] The present invention adopts highly flat and wrinkle-resistant kraft paper as a substrate, the smoothness of the kraft paper should be controlled within the Bekk smoothness of 300S-400S, and the stiffness of the kraft paper should be controlled between 20 and 30mN·m. The kraft paper can enhance the overall strength of the cover film while enhancing the flatness and stiffness of the cover film. High-flat particles are added to the polyethylene coating layer and the high-flat particle heat-sealing layer. The high-flat particles can interact with the polymer resin in the polyethylene coating layer and the high-flat particle heat-sealing layer during processing, adjust the arrangement and crystallization behavior of the molecular chains, reduce the unevenness of the cover film caused by inconsistent molecular chain orientation or uneven crystallization, and further improve the cover film.

[0007] It is further configured as follows: the polyethylene coating layer and the high-flatness particle heat-sealing layer are both composed of LDPE and the above-mentioned high-flatness particles.

[0008] It is further configured as follows: the high-flat particles are composed of high-density PE granules such as HDPE and MDPE.

[0009] It is further configured as follows: the polyethylene coating layer is formed by coating a combination of LDPE pellets with a weight ratio of 70-80%, MDPE pellets with a weight ratio of 10-15%, and HDPE pellets with a weight ratio of 10-15%. The thickness of the polyethylene coating layer is 10-20 μm.

[0010] It is further configured as follows: the high-flat particle heat-sealing layer is formed by laminating a combination of LDPE, MDPE and HDPE pellets with a weight ratio of 60-70%, 10-20%, and the thickness of the high-flat particle heat-sealing layer is 40-60 μm.

[0011] It is further configured as follows: the mass of the kraft paper is 50-70 grams per square meter.

[0012] It is further configured as follows: the barrier layer is a metal aluminum film, and the thickness of the metal aluminum film is 6-9 μm.

[0013] It is further configured as follows: the ink layer is composed of nitrocellulose resin, polyurethane resin, color powder and solvent.

[0014] It is further configured that: the adhesive layer is polyurethane resin.

[0015] In summary, the invention has the following characteristics: 1. By adding high-flat particles to the polyethylene coating layer and the high-flat particle heat-sealing layer, the molecular chain arrangement and crystallization behavior of the internal polymer resin are adjusted by the high-flat particles, thereby reducing the unevenness of the cover film caused by inconsistent molecular chain orientation or uneven crystallization; 2. High-flat kraft paper is used as the base material to enhance the overall strength of the cover film while enhancing the flatness and stiffness of the cover film. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the invention patent structure Figure 1 , showing the overall structure of the invention.

[0017] In the figure: 1. ink layer; 2. PET layer; 3. adhesive layer; 4. paper layer; 5. polyethylene coating layer; 6. barrier layer; 7. high-flatness particle heat sealing layer. DETAILED DESCRIPTION

[0018] In order to enable those skilled in the art to better understand the technical solution of the invention, the invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present application and the features therein may be combined with each other without conflict.

[0019] In the description of the invention, it should be noted that the terms "upper", "lower", "inside", "outside", "top / bottom" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the invention.

[0020] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "provided with", "set / connected", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0021] The invention is described in detail below with reference to the accompanying drawings.

[0022] A high flatness cover film, such as Figure 1 As shown, it includes an ink layer, a PET layer, a paper layer, a polyethylene coating layer, a barrier layer and a high-flatness particle heat sealing layer. The paper layer is a kraft paper with high flatness and wrinkle resistance. An adhesive layer is provided between the PET layer and the paper layer. High-flatness particles are added to the polyethylene coating layer and the high-flatness particle heat sealing layer.

[0023] In summary, the PET layer is bonded to the paper layer through an adhesive layer, the adhesive layer is polyurethane resin, and then the ink is printed or sprayed on the PET layer. The ink layer can be made of ink composed of nitrocellulose resin, polyurethane resin, color powder and solvent. The ink of this composition has good adhesion and can be more firmly attached to the PET layer. The PET layer can also further increase the adhesion of the ink and improve the barrier properties of the cover film. The polyethylene coating layer is covered on the side of the paper layer away from the PET layer in the form of a coating, and then the metal aluminum film is pressed on the polyethylene coating layer. The polyethylene coating layer will play a bonding role, and the metal aluminum film can further improve the overall barrier properties of the cover film.

[0024] Specifically, by using highly flat and wrinkle-resistant kraft paper as the substrate, the smoothness of the kraft paper should be controlled within the Bekk smoothness of 300-400S, and the stiffness of the kraft paper should be controlled between 20 and 30 mN·m. The kraft paper can enhance the overall strength of the cover film while enhancing the flatness and stiffness of the cover film.

[0025] Specifically, the polyethylene coating layer and the high-flatness particle heat-sealing layer are both composed of LDPE and the above-mentioned high-flatness particles, the high-flatness particles are composed of high-density PE granules such as HDPE and MDPE, the polyethylene coating layer is formed by coating a combination of LDPE granules with a weight ratio of 70-80%, MDPE granules with a weight ratio of 10-15%, and HDPE granules with a weight ratio of 10-15%, and the high-flatness particle heat-sealing layer is formed by coating a combination of LDPE with a weight ratio of 60-70%, MDPE with a weight ratio of 10-20%, and HDPE granules with a weight ratio of 15-20%. By adding high-flatness particles to the polyethylene coating layer and the high-flatness particle heat-sealing layer, the high-flatness particles can interact with the polymer resin in the polyethylene coating layer and the high-flatness particle heat-sealing layer during processing, adjust the arrangement and crystallization behavior of the molecular chains, reduce the unevenness of the cover film caused by inconsistent molecular chain orientation or uneven crystallization, and further improve the flatness of the cover film.

[0026] Specifically, in order to control the overall thickness of the cover film within a reasonable range, the thickness of the polyethylene coating layer should be controlled at 10-20μm, the thickness of the high-flatness particle heat sealing layer should be controlled at 40-60μm, the mass of kraft paper should be controlled at 50-70 grams per square meter, and the thickness of the metal aluminum film should be controlled at 6-9μm, ensuring the overall flexibility of the cover film while ensuring strength and stiffness.

[0027] On the basis of the above, antistatic agents can be added to both sides of the finished film to prevent the cover film from not fitting the product well enough due to static absorption of dust and other impurities during use. Adding a lubricant can improve the surface friction performance of the cover film, making it easier to roll up and unfold the cover film.

[0028] The above is only a preferred embodiment of the invention, and the protection scope of the invention is not limited to the above embodiments. All technical solutions under the inventive concept belong to the protection scope of the invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the invention should also be regarded as the protection scope of the invention.

Claims

1. A cover film with high flatness, characterized in that: The invention comprises an ink layer (1), a PET layer (2), a paper layer (4), a polyethylene coating layer (5), a barrier layer (6) and a high-flatness particle heat-sealing layer (7); the paper layer (4) is kraft paper with high flatness and wrinkle resistance; an adhesive layer (3) is arranged between the PET layer (2) and the paper layer (4); and high-flatness particles are added to the polyethylene coating layer (5) and the high-flatness particle heat-sealing layer (7).

2. A cover film with high flatness according to claim 1, characterized in that: The polyethylene coating layer (5) and the high-flatness particle heat-sealing layer (7) are both composed of LDPE and the above-mentioned high-flatness particles.

3. A cover film with high flatness according to claim 2, characterized in that: High-flat particles are composed of high-density PE granules such as HDPE and MDPE.

4. A cover film with high flatness according to claim 3, characterized in that: The polyethylene coating layer (5) is formed by coating a combination of LDPE granules in a weight ratio of 70-80%, MDPE granules in a weight ratio of 10-15%, and HDPE granules in a weight ratio of 10-15%. The thickness of the polyethylene coating layer (5) is 10-20 μm.

5. The high-flatness cover film according to claim 3, characterized in that: The high-flat particle heat-sealing layer (7) is formed by laminating a combination of LDPE, MDPE and HDPE granules in a weight ratio of 60-70%, 10-20%, and 15-20%. The thickness of the high-flat particle heat-sealing layer (7) is 40-60 μm.

6. A cover film with high flatness according to claim 1, characterized in that: The weight of the kraft paper is 50-70 grams per square meter.

7. The high-flatness cover film according to claim 1, characterized in that: The barrier layer (6) is a metal aluminum film, and the thickness of the metal aluminum film is 6-9 μm.

8. The high-flatness cover film according to claim 1, characterized in that: The ink layer (1) is composed of nitrocellulose resin, polyurethane resin, color powder and solvent.

9. A cover film with high flatness according to claim 1, characterized in that: The adhesive layer (3) is polyurethane resin.

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