Anti-fog high-barrier matt film and preparation method thereof

Abstract

The present invention belongs to the field of thin films and relates to an anti-fog high-barrier matt film and a preparation method thereof. The anti-fog high-barrier matt film comprises an anti-fog barrier matt layer, a core layer, and a primer layer, which are arranged in sequence; the anti-fog barrier matt layer comprises random copolymer polypropylene, 40-46wt% high-density polyethylene, 4-10wt% N-(n-alkyl) diethanolamine acrylate grafted modified propylene-norbornene copolymer, and 1-2wt% maleic anhydride grafted homopolypropylene; the core layer comprises homopolypropylene; and the primer layer comprises ethylene-octene copolymer, 10-15wt% propylene-butene copolymer, and 2-5wt% alkyl maleate grafted modified ethylene-vinyl acetate copolymer. The anti-fog high-barrier matt film of the present invention not only helps to improve the bonding strength between the film primer layer and the applied hot melt adhesive layer, but also has both anti-fog and barrier properties, and can be applied to extreme humid environments.

Description

Technical Field

[0001] The present invention relates to the field of films, and in particular to an anti-fog high-barrier matt film and a preparation method thereof. Background Art

[0002] BOPP film is a packaging film that is stretched longitudinally and then transversely, typically in a 3-5-layer co-extruded composite structure. This multiple stretching exhibits excellent mechanical and optical properties, along with advantages such as lightweight, printability, and moisture resistance. Traditionally, direct coating of BOPP film with EVA hot-melt adhesive results in poor adhesion between the EVA and the homopolymer PP in the film. Therefore, prior to adhesive application, an AC agent (a high molecular weight polyethyleneimine aqueous solution) is typically applied offline, followed by EVA coating. Because the organic solvents used in the AC agent application stage are hazardous to both humans and the environment, and the offline adhesive application followed by lamination is inefficient, a primer-coated BOPP film has been developed. This primer-coated BOPP film incorporates a primer layer on one surface layer during extrusion, replacing the traditional AC agent. This allows for direct application of EVA hot-melt adhesive in downstream applications, eliminating a step in the offline adhesive application process and providing greater energy efficiency and environmental protection.

[0003] However, due to the poor barrier properties of the primer-containing films currently on the market, the primer layer generally has insufficient adhesion when compounded with the EVA coating. Moreover, in extremely humid environments, such as the return of south wind, the anti-fog performance of the film also needs to be considered so that the patterns and text on the printed parts can be clearly seen after lamination.

[0004] The existing technology generally achieves the anti-fog performance of the film by adding anti-fog agents. Anti-fog agents are mainly divided into internal addition type and external coating type. Internal addition type anti-fog agents are mixed with PP resin during the film production process. Commonly used ones include polyol fatty acid esters and polyglycerol fatty acid esters. These anti-fog agents can reduce the surface tension of the film surface, so that water vapor forms a uniform water film on the film surface instead of water droplets, thereby achieving the anti-fog effect. Since anti-fog agents are essentially surfactants, and surfactants have a lubricating effect, when the content of anti-fog agents is high during processing and mixing, it will cause the screw to slip, which will cause the anti-fog agent to be unevenly dispersed in the resin matrix. Although external coating type anti-fog agents can be sprayed multiple times to make up for the defect of insufficient anti-fog life of films prepared by internal addition type anti-fog agents, the bonding force between external coating type anti-fog agents and the substrate is weak, so their water resistance and anti-scouring properties are poor, and external coating type anti-fog agents must be evenly coated on the substrate surface to achieve continuous and stable anti-fog properties. However, whether it is internal coating or external anti-fog agent, there is a migration problem, which affects the timeliness of the anti-fog effect. Summary of the Invention

[0005] Based on this, the purpose of the present invention is to provide an anti-fog high-barrier matte film and its preparation method, which is beneficial to improve the bonding strength between the film base coating and the coated hot melt adhesive layer, has both anti-fog and barrier properties, and can be used in extreme humid environments.

[0006] First aspect:

[0007] An anti-fog high-barrier matt film, comprising an anti-fog barrier matt layer, a core layer and a primer layer arranged in sequence;

[0008] The anti-fog barrier matt layer comprises random copolymerized polypropylene, 40-46 wt% high-density polyethylene, 4-10 wt% N-(n-alkyl) diethanolamine acrylate grafted modified propylene-norbornene copolymer, and 1-2 wt% maleic anhydride grafted homopolypropylene; wherein the grafting rate of N-(n-alkyl) diethanolamine acrylate in the N-(n-alkyl) diethanolamine acrylate grafted modified propylene-norbornene copolymer is 1-2.5%, and n is any integer between 14 and 18;

[0009] The core layer comprises homopolypropylene;

[0010] The primer layer comprises ethylene-octene copolymer, 10-15 wt% propylene-butene copolymer and 2-5 wt% alkyl maleate grafted modified ethylene-vinyl acetate copolymer; wherein the grafting rate of alkyl maleate in the alkyl maleate grafted modified ethylene-vinyl acetate copolymer is 12-30%.

[0011] The anti-fog barrier matte film described herein, by incorporating N-(n-alkyl) diethanolamine acrylate graft-modified propylene-norbornene copolymer (where N represents nitrogen and n represents the alkyl chain length) into the anti-fog barrier matte layer, not only imparts excellent anti-fog properties but also possesses certain barrier properties. This enhanced barrier property improves the adhesion between the film's primer and hot-melt adhesive in humid environments. Furthermore, the incorporation of alkyl maleate graft-modified ethylene-vinyl acetate copolymer into the primer further enhances the adhesion between the primer and the hot-melt adhesive. The synergistic effects of the distinct functionalities of the anti-fog barrier matte layer and the primer effectively strengthen the adhesion between the primer and the hot-melt adhesive in humid environments.

[0012] The inventors of the present application have found in experiments that N-(n-alkyl) diethanolamine acrylate grafted modified propylene-norbornene copolymer has certain anti-fog properties. The N-(n-alkyl) diethanolamine acrylate grafted modified propylene-norbornene copolymer is oriented, and its hydrophilic side chain segments tend to move away from the low-polarity resin matrix and toward the outside of the film, forming a hydrophilic layer on the film surface, while the hydrophobic main chain segments tend to move toward the core layer. In this way, water droplets can form a uniform, transparent and thin water film on the surface of the film, which eliminates the problem of fogging caused by a large number of dispersed water droplets. The diffuse reflection of light will not be affected, so it will not affect the light transmittance of the film, and play an anti-fog effect; the main chain segment of the propylene-norbornene copolymer has a ring structure, which can play a certain barrier role, which is beneficial to reduce the continued migration of moisture in the water film into the interior of the film; and it has good melt fluidity, which is not only beneficial to ensure the uniformity of the matte effect of the matte layer, but also beneficial to the uniform roughening of the surface of the anti-fog barrier matte layer, improving the adhesion problem between the matte film itself (anti-fog barrier matte layer and primer layer), and improving the smoothness of film winding and unwinding during the manufacturing process.

[0013] In order to enable the film to obtain suitable anti-fog and barrier properties, the present invention adds 4-10wt% of N-(n-alkyl) diethanolamine acrylate monoester grafted modified propylene-norbornene copolymer to the anti-fog barrier matt layer. If the addition amount of N-(n-alkyl) diethanolamine acrylate monoester grafted modified propylene-norbornene copolymer is too low, it cannot effectively improve the anti-fog performance of the film, nor can it improve the barrier performance to cooperate with the primer layer to improve the bonding strength between the primer layer and the hot melt adhesive layer in a humid environment. If the addition amount is too high, it is not conducive to its own dispersion in the anti-fog barrier matt layer, and the compatibility becomes poor, resulting in a large difference in viscosity with the core layer, making the thick film "incompatible", thereby failing to obtain a film with uniform thickness and gloss, which is not conducive to biaxial stretching of the film, and thus cannot be normal continuous production. Furthermore, the inventors controlled the grafting rate of N-(n-alkyl) diethanolamine acrylate in the N-(n-alkyl) diethanolamine acrylate grafted modified propylene-norbornene copolymer to be 1-2.5%. If the grafting rate is too low, the hydrophilic groups are too few and cannot play an effective anti-fog role. If the grafting rate is too high, the intermolecular forces such as hydrogen bonds between the N-(n-alkyl) diethanolamine acrylate grafted modified propylene-norbornene copolymer molecules are too strong, forming a physical cross-linked structure, resulting in poor compatibility with other components of the matte layer, making it impossible to disperse evenly in the matte layer, and also not conducive to biaxial stretching.

[0014] Furthermore, the long alkyl chain of the N-(n-alkyl)diethanolamine acrylate grafted onto the propylene-norbornene copolymer presents significant steric hindrance, which, to a certain extent, limits the migration of water molecules into the film. To ensure that the film's anti-fog barrier layer possesses suitable barrier properties and synergizes with the cyclic structure of norbornene to achieve a better barrier effect, the inventors controlled the alkyl chain length to be between 14 and 18 (i.e., n is any integer between 14 and 18). Excessively long alkyl chains can lead to excessive steric hindrance, hindering the grafting of N-(n-alkyl)diethanolamine acrylate onto the propylene-norbornene copolymer chain to achieve a graft copolymer with an appropriate grafting ratio. Excessively short alkyl chains can prevent the propylene-norbornene copolymer from effectively enhancing its barrier properties. Preferably, the alkyl group is an n-alkyl group.

[0015] The present invention also adds 1-2 wt% of maleic anhydride grafted homopolymerized polypropylene to the anti-fog barrier matt layer, so that the N-(n-alkyl) diethanolamine acrylate grafted modified propylene-norbornene copolymer is evenly dispersed in the anti-fog barrier matt layer, while enhancing the bonding force between the anti-fog barrier matt layer with greater polarity and the core layer, ensuring that no stratification occurs during production and use.

[0016] In order to effectively enhance the bonding strength between the film base coat and the hot melt adhesive in a humid environment, the present invention adds 2-5wt% of alkyl maleate grafted modified ethylene-vinyl acetate copolymer to the base coat. The polar ester content in the alkyl maleate grafted modified ethylene-vinyl acetate copolymer is higher than that in the ethylene-vinyl acetate copolymer. On the one hand, it makes the bonding between the base coat and the hot melt adhesive layer stronger. On the other hand, it cooperates with the barrier effect of the anti-fog barrier matt layer, making it more suitable for enhancing the bonding strength with the hot melt adhesive layer in a humid environment, which is beneficial to ensuring the lamination quality of the printed part. If the content of the alkyl maleate grafted modified ethylene-vinyl acetate copolymer in the base coat is too high, the base coat will be too sticky, which is not conducive to the smoothness of the film winding and unwinding, and will cause the polarity difference between the base coat and the core layer to be too large, resulting in delamination during the biaxial stretching process. If the content is too low, the bonding strength between the base coat and the hot melt adhesive layer cannot be effectively enhanced, which is not conducive to the application of the film in a highly humid environment. To ensure adequate adhesion between the primer layer and the hot-melt adhesive layer in humid environments, the inventors also controlled the grafting ratio of the alkyl maleate in the alkyl maleate-grafted ethylene-vinyl acetate copolymer to 12-30%. If the grafting ratio is too high, the thermal stability of the alkyl maleate-grafted ethylene-vinyl acetate copolymer itself will decrease, and thermal decomposition may occur at the production process temperature of the present invention, affecting the film's appearance quality and production stability. If the grafting ratio is too low, the polar ester group content in the alkyl maleate-grafted ethylene-vinyl acetate copolymer is too low, and it cannot cooperate with the anti-fog barrier matte layer to improve the bonding strength between the primer layer and the hot-melt adhesive layer in humid environments. The synergistic effect of the anti-fog barrier matte layer and the primer layer effectively enhances the bonding strength between the primer layer and the hot-melt adhesive in humid environments.

[0017] In the present invention, the primer layer of the film includes 10-15wt% propylene-butene copolymer, which is used to improve the interface compatibility between the primer layer and the core layer. If the added amount is less than 10wt%, the interlayer bonding strength between the primer layer and the core layer is low, and the bonding strength between the two layers cannot be effectively improved. If the added amount is greater than 15wt%, the compatibility between the primer layer and the EVA hot melt adhesive layer is poor, which is not conducive to the bonding between the primer layer and the EVA hot melt adhesive layer.

[0018] The anti-fog barrier matte film described in the present invention is a biaxially oriented polypropylene film that contains a primer coating. This film eliminates the need for a secondary primer coating during use, making it energy-efficient and environmentally friendly. It not only exhibits excellent anti-fog properties, allowing for clear viewing of patterns and text on printed parts even when exposed to water, but also exhibits a certain degree of barrier properties. The synergistic effects of the film's anti-fog barrier matte layer and primer coating improve the bonding between the primer coating and the hot-melt adhesive layer, thereby enhancing the composite strength between the film and the printed part, making it suitable for use in some humid, extreme environments. Furthermore, by synergizing the differential functions of the anti-fog barrier matte layer and primer coating, the film is smooth and non-sticky to rollers during biaxial oriented production, and allows for smooth winding and unwinding during film production and application.

[0019] As a preferred embodiment, at 230°C and a load of 2.16 kg, the melt index of the N-(n-alkyl)diethanolamine acrylate monoester grafted modified propylene-norbornene copolymer is 5-10 g / 10 min; the N-(n-alkyl)diethanolamine acrylate monoester grafted modified propylene-norbornene copolymer is formed by grafting a propylene-norbornene copolymer onto an N-(n-alkyl)diethanolamine acrylate monoester, and the molar content of norbornene in the propylene-norbornene copolymer is 25-28%.

[0020] Controlling the melt index of the N-(n-alkyl)diethanolamine acrylate-modified propylene-norbornene copolymer to 5-10 g / 10 min facilitates melt compatibility with the other components of the anti-fog barrier matte layer, resulting in a thick sheet suitable for biaxial stretching and ensuring a smooth biaxial stretching process. The inventors also controlled the norbornene content to impart a certain stiffness to the anti-fog barrier matte layer during the manufacturing process, reducing the adhesion between the inner and outer layers of the film (i.e., between the primer and the anti-fog barrier matte layer), thereby ensuring smooth film production and winding and unwinding.

[0021] As a preferred embodiment, the random copolymer polypropylene has a melt index of 6-10 g / 10 min at 230°C and a load of 2.16 kg; the high-density polyethylene has a melt index of 9-20 g / 10 min at 190°C and a load of 2.16 kg. The random copolymer polypropylene is selected from one or both of ethylene-propylene copolymer polypropylene and ethylene-propylene-butylene copolymer polypropylene. Selecting random copolymer polypropylene and high-density polyethylene within these melt index ranges ensures that the anti-fog barrier matte layer has suitable melt flow properties, improves overall melt flow compatibility, and facilitates obtaining a film with excellent overall matte effect.

[0022] As a preferred solution, the homopolypropylene has an isotacticity of 90-99% and a melt index of 3.5-3.8 g / 10 min at 230° C. and a load of 2.16 kg, which is beneficial to ensuring the overall mechanical properties of the film and improving the compatibility between the homopolypropylene in the core layer and the primer component to avoid interlayer delamination.

[0023] As a preferred embodiment, at 190°C and a load of 2.16 kg, the melt index of the alkyl maleate grafted modified ethylene-vinyl acetate copolymer is 26-28 g / 10 min; the melting point of the alkyl maleate grafted modified ethylene-vinyl acetate copolymer is 80-90°C; the alkyl maleate grafted modified ethylene-vinyl acetate copolymer is modified from the alkyl maleate grafted ethylene-vinyl acetate copolymer, and the melt index of the ethylene-vinyl acetate copolymer is 20-25 g / 10 min. Controlling the melt index of the alkyl maleate grafted modified ethylene-vinyl acetate copolymer to 26-28 g / 10 min and the melting point to 80-90°C helps improve the compatibility of the alkyl maleate grafted modified ethylene-vinyl acetate copolymer with other components of the primer layer and enhances the bonding between the primer layer and the hot melt adhesive layer.

[0024] As a preferred embodiment, the alkyl maleate in the alkyl maleate graft-modified ethylene-vinyl acetate copolymer has a diester structure and is a dialkyl maleate. The alkyl maleate is either di-n-octyl maleate or di-n-butyl maleate. In a specific embodiment, the alkyl maleate graft-modified ethylene-vinyl acetate copolymer is obtained by free radical polymerization of an alkyl maleate and an ethylene-vinyl acetate copolymer, and the alkyl maleate is obtained by esterification of an alkyl alcohol and maleic acid. The alkyl maleate is preferably either di-n-octyl maleate or di-n-butyl maleate, which helps further improve the compatibility of the alkyl maleate graft-modified ethylene-vinyl acetate copolymer with other components of the primer layer.

[0025] As a preferred embodiment, the melting point of the ethylene-octene copolymer is 75-95°C, and the melting point of the propylene-butene copolymer is 80-95°C. This helps to avoid roller sticking during the production process and improves the compatibility and interlayer bonding strength between the primer layer and the subsequently applied EVA hot melt adhesive. If the melting point of the ethylene-octene copolymer is less than 75°C, the primer layer is prone to roller sticking during longitudinal stretching, causing defects on the film surface and making it easy for the film to stick or even become unwound when rolled under high tension; if the melting point of the ethylene-octene copolymer is greater than 95°C, the compatibility and interlayer bonding strength between the primer layer and the subsequently applied EVA hot melt adhesive decreases; if the melting point of the propylene-butene copolymer is less than 80°C, the primer layer is prone to roller sticking during longitudinal stretching; if the melting point of the propylene-butene copolymer is greater than 95°C, the compatibility and interlayer bonding strength between the primer layer and the subsequently applied EVA hot melt adhesive decreases. In addition, the melting points of propylene-butene copolymer and ethylene-octene copolymer should be close. If the difference in melting points is too large, it will be detrimental to the bonding between the primer layer and the subsequently coated EVA hot melt adhesive layer.

[0026] As a preferred solution, the primer layer further comprises 0.5-1 wt % of a polyorganosiloxane elastomer, and the particle size D90 of the polyorganosiloxane elastomer is 3-5 μm.

[0027] Adding a polyorganosiloxane elastomer of appropriate particle size to the basecoat improves its anti-blocking properties, preventing contact between the inner and outer layers (i.e., the basecoat and the anti-fog, barrier, and matte layer) when the film is rolled, thus ensuring smoother winding and unwinding. Furthermore, antioxidants can be added to the basecoat to mitigate thermal oxidative degradation and further crosslinking of the low-melting-point polyolefin resin during high-temperature extrusion, thus reducing uneven film stretching and other quality issues.

[0028] Second aspect:

[0029] A method for preparing the anti-fog high-barrier matte film according to the first aspect comprises the following steps:

[0030] The component raw materials of the anti-fog barrier matt layer, the core layer, and the primer layer are respectively put into a batching unit, and after being measured, they are co-extruded through an extruder, merged in a three-layer die after passing through a flow channel distributor, and then cooled by a chilled roller to form a thick sheet. The thick sheet is biaxially stretched by a stretching roller to form a film, and the film is cooled and simultaneously thickness-controlled by a trimming machine, and then corona and / or flame treated to obtain the anti-fog high-barrier matt film.

[0031] As a preferred embodiment, the extruder's primer chute and the stretching rollers used for biaxial stretching are provided with a Teflon coating. The Teflon coating helps prevent the alkyl maleate-grafted modified ethylene-vinyl acetate copolymer in the primer from adhering to other primer components during extrusion and stretching, thereby preventing smooth processing and film surface integrity. The appropriate viscosity of the alkyl maleate-grafted modified ethylene-vinyl acetate copolymer also prevents film slippage and scratching on the Teflon-coated stretching rollers. DETAILED DESCRIPTION

[0032] The present invention will be described more fully below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Experimental methods in the following examples or comparative examples, where specific conditions are not specified, generally follow conditions conventional in the art or conditions recommended by the manufacturer; raw materials and reagents used, unless otherwise specified, are all commercially available from conventional markets.

[0033] As an embodiment, this embodiment provides an anti-fog high-barrier matt film, comprising an anti-fog barrier matt layer, a core layer and a primer layer arranged in sequence;

[0034] The anti-fog barrier matt layer comprises random copolymerized polypropylene (random copolymerized PP), 40-46 wt% high-density polyethylene (HDPE), 4-10 wt% N-(n-alkyl) diethanolamine acrylate grafted modified propylene-norbornene copolymer, and 1-2 wt% maleic anhydride grafted homopolypropylene; wherein the grafting rate of N-(n-alkyl) diethanolamine acrylate grafted modified propylene-norbornene copolymer is 1-2.5%, n is any integer between 14 and 18, and the alkyl group is a normal alkyl group;

[0035] The core layer comprises homopolymer polypropylene;

[0036] The primer layer comprises ethylene-octene copolymer, 10-15wt% propylene-butene copolymer and 2-5wt% alkyl maleate grafted modified ethylene-vinyl acetate copolymer; wherein the grafting rate of alkyl maleate in the alkyl maleate grafted modified ethylene-vinyl acetate copolymer is 12-30%.

[0037] Furthermore, at 230°C and under a load of 2.16 kg, the melt index of the propylene-norbornene copolymer grafted with N-(n-alkyl)diethanolamine acrylate is 5-10 g / 10 min; the propylene-norbornene copolymer grafted with N-(n-alkyl)diethanolamine acrylate is modified by grafting a propylene-norbornene copolymer with N-(n-alkyl)diethanolamine acrylate, and the molar content of norbornene in the propylene-norbornene copolymer is 25-28%.

[0038] Furthermore, at 230°C and a load of 2.16 kg, the melt index of the random copolymer polypropylene is 6~10 g / 10 min; at 190°C and a load of 2.16 kg, the melt index of the high-density polyethylene is 9~20 g / 10 min; the random copolymer polypropylene is selected from one or both of ethylene-propylene copolymer polypropylene and ethylene-propylene-butene copolymer polypropylene.

[0039] Furthermore, the isotacticity of the homopolypropylene is 90-99%, and the melt index is 3.5-3.8 g / 10 min at 230° C. and a load of 2.16 kg.

[0040] Furthermore, the core layer further comprises 1-2 wt % of an antistatic agent.

[0041] Furthermore, at 190°C and a load of 2.16 kg, the melt index of the alkyl maleate grafted modified ethylene-vinyl acetate copolymer is 26-28 g / 10 min; the melting point of the alkyl maleate grafted modified ethylene-vinyl acetate copolymer is 80-90°C; the alkyl maleate grafted modified ethylene-vinyl acetate copolymer is modified from the alkyl maleate grafted ethylene-vinyl acetate copolymer, and the melt index of the ethylene-vinyl acetate copolymer is 20-25 g / 10 min.

[0042] Furthermore, the alkyl maleate in the alkyl maleate grafted modified ethylene-vinyl acetate copolymer has a diester structure and belongs to a dialkyl maleate, and the alkyl maleate is any one of di-n-octyl maleate and di-n-butyl maleate.

[0043] Furthermore, the alkyl maleate grafted modified ethylene-vinyl acetate copolymer is obtained by free radical polymerization of alkyl maleate and ethylene-vinyl acetate copolymer, and the alkyl maleate is obtained by esterification of alkyl alcohol and maleic anhydride.

[0044] Furthermore, the melting point of the ethylene-octene copolymer is 75-95°C, and the melting point of the propylene-butene copolymer is 80-95°C.

[0045] Furthermore, the primer layer further comprises 0.5-1 wt % of a polyorganosiloxane elastomer, and the particle size D90 of the polyorganosiloxane elastomer is 3-5 μm.

[0046] Furthermore, the primer layer further includes 0.1-0.3 wt % of an antioxidant, and the antioxidant is compounded by antioxidant 1010 and antioxidant 168 in a mass ratio of 1:2.

[0047] Furthermore, the total thickness of the prepared film is 14-25 μm, including a 1.6-2.0 μm anti-fog barrier matt layer, a core layer and a 1-2 μm primer layer.

[0048] The present invention also provides a method for preparing an anti-fog high-barrier matt film, comprising the following steps:

[0049] The component raw materials of the anti-fog barrier matt layer, core layer and primer layer are respectively put into the batching unit, measured and co-extruded through the extruder, merged in the three-layer die after passing through the flow channel distributor, and then cooled by the chilled roller to form a thick sheet. The thick sheet is biaxially stretched by the stretching roller to form a film, and the film is cooled and the thickness is controlled by the trimming machine at the same time. After corona and / or flame treatment, the anti-fog high barrier matt film is obtained.

[0050] Furthermore, the surface of the primer coating feed chute of the extruder and the surface of the stretching roller used in the biaxial stretching are provided with a Teflon coating.

[0051] As shown in Table 1, it is a summary table of the components and contents of each layer of Examples 1-3 and Comparative Examples 1-10.

[0052] Some raw materials and their parameters are as follows:

[0053] In the anti-fog barrier matt layer, the N-(n-alkyl) diethanolamine acrylate grafted modified propylene-norbornene copolymer is prepared by plasma-treating the propylene-norbornene copolymer and then grafting it with N-(n-alkyl) diethanolamine acrylate. At 230°C and a load of 2.16 kg, the melt index is 8 g / 10 min, and the n-alkyl group is a normal alkyl group. The molar content of norbornene in the propylene-norbornene copolymer is 26%.

[0054] The random copolymer polypropylene is ethylene-propylene copolymer polypropylene, and has a melt index of 8 g / 10 min at 230° C. and a load of 2.16 kg; and a melt index of the high-density polyethylene is 11 g / 10 min at 190° C. and a load of 2.16 kg.

[0055] In the core layer, the antistatic agent selected is glycerol monostearate.

[0056] In the primer layer, the melt index of the alkyl maleate grafted modified ethylene-vinyl acetate copolymer is 26 g / 10 min, the melting point is 85°C, and the alkyl maleate is di-n-octyl maleate; the melt index of the ethylene-vinyl acetate copolymer is 20 g / 10 min; the melting point of the ethylene-octene copolymer is 85°C, and the melt index is 6.5 g / 10 min; the melting point of the propylene-butene copolymer is 85°C, and the melt index is 7 g / 10 min; the particle size D90 of the polysiloxane elastomer is 5 μm; the antioxidant is compounded by antioxidant 1010 and antioxidant 168 in a mass ratio of 1:2.

[0057] Table 1 - Composition of each layer in each embodiment and comparative example

[0058]

[0059] Example 1

[0060] This embodiment provides an anti-fog high-barrier matt film with a total thickness of 18 μm, including a 2.0 μm anti-fog barrier matt layer, a 14.2 μm core layer and a 1.8 μm primer layer.

[0061] The anti-fog barrier matt layer comprises 40 wt% high-density polyethylene, 4 wt% N-tetradecyldiethanolamine monoacrylate grafted modified propylene-norbornene copolymer, 1 wt% maleic anhydride grafted homopolypropylene, and 55 wt% random copolymer polypropylene. The graft ratio of N-tetradecyldiethanolamine monoacrylate in the N-tetradecyldiethanolamine monoacrylate grafted modified propylene-norbornene copolymer is 1 wt%.

[0062] The core layer comprises 99 wt% homopolypropylene having an isotacticity of 95% and a melt index of 3.6 g / 10 min and 1 wt% antistatic agent.

[0063] The primer layer comprises 10 wt% of a propylene-butene copolymer, 2 wt% of an ethylene-vinyl acetate copolymer modified with an alkyl maleate graft, 0.5 wt% of a polyorganosiloxane elastomer, 0.1 wt% of an antioxidant, and 87.4 wt% of an ethylene-octene copolymer. The grafting ratio of the alkyl maleate in the ethylene-vinyl acetate copolymer modified with the alkyl maleate graft is 12 wt%.

[0064] This embodiment also provides a method for preparing an anti-fog high-barrier matt film, comprising the following steps:

[0065] The component raw materials of the anti-fog barrier matt layer, the core layer and the primer layer are respectively put into the batching unit to obtain the anti-fog barrier matt layer resin, the core layer resin and the primer layer resin respectively.

[0066] The resin of each layer is transported to three screw extruders through a batcher (the base coat and matte layer are both single-screw extruders, the core layer is a twin-screw extruder, the extrusion temperature of the base coat is 235°C, the extrusion temperature of the anti-fog barrier matte layer is set to 245°C, and the extrusion temperature of the core layer is 250°C). The melt of the three extruders is measured by a melt metering pump, passes through a narrow flow channel and merges into a thick sheet at the T-die head. The thick sheet is cooled by a chilled roller and enters a chilled water tank, and then passes through a water blowing chamber and enters the longitudinal stretching area for Longitudinal stretching (primer coating: preheating zone temperature is 70℃, stretching zone temperature is 60℃, and setting zone temperature is 65℃; anti-fog barrier matt layer: preheating zone temperature is 135℃, stretching zone temperature is 130℃, and setting zone temperature is 130℃; longitudinal stretching ratio is 5 times), and then enters the transverse stretching area for transverse stretching (stretching temperature is 160℃, transverse stretching ratio is 8 times), followed by trimming and corona treatment after setting, and then reeled into aging rack for treatment. After treatment, it is slit and packaged into finished products.

[0067] Example 2

[0068] This embodiment provides an anti-fog high-barrier matt film with a total thickness of 18 μm, including a 2.0 μm anti-fog barrier matt layer, a 14.2 μm core layer and a 1.8 μm primer layer.

[0069] The anti-fog barrier matt layer comprises 43 wt% high-density polyethylene, 7 wt% propylene-norbornene copolymer grafted with N-hexadecyldiethanolamine monoacrylate, 1.2 wt% homopolypropylene grafted with maleic anhydride, and 48.8 wt% random copolymer polypropylene. The graft ratio of N-hexadecyldiethanolamine monoacrylate in the propylene-norbornene copolymer grafted with N-hexadecyldiethanolamine monoacrylate is 1.5 wt%.

[0070] The core layer comprises 99 wt% homopolypropylene having an isotacticity of 95% and a melt index of 3.6 g / 10 min and 1 wt% antistatic agent.

[0071] The primer layer comprises 12 wt% of a propylene-butene copolymer, 3.5 wt% of an ethylene-vinyl acetate copolymer modified with an alkyl maleate graft, 0.5 wt% of a polyorganosiloxane elastomer, 0.1 wt% of an antioxidant, and 83.9 wt% of an ethylene-octene copolymer. The grafting ratio of the alkyl maleate in the ethylene-vinyl acetate copolymer modified with the alkyl maleate graft is 20 wt%.

[0072] The preparation method of the anti-fog high-barrier matt film of this embodiment is the same as that of Example 1.

[0073] Example 3

[0074] This embodiment provides an anti-fog high-barrier matt film with a total thickness of 18 μm, including a 2.0 μm anti-fog barrier matt layer, a 14.2 μm core layer and a 1.8 μm primer layer.

[0075] The anti-fog barrier matt layer comprises 46 wt% high-density polyethylene, 10 wt% N-octadecyldiethanolamine acrylate-grafted modified propylene-norbornene copolymer, 1.5 wt% maleic anhydride-grafted homopolypropylene, and 42.5 wt% random copolymer polypropylene. The grafting ratio of N-octadecyldiethanolamine acrylate-grafted modified propylene-norbornene copolymer is 2.5 wt%.

[0076] The core layer comprises 99 wt% homopolypropylene having an isotacticity of 95% and a melt index of 3.6 g / 10 min and 1 wt% antistatic agent.

[0077] The primer layer comprises 15 wt% of a propylene-butene copolymer, 5 wt% of an ethylene-vinyl acetate copolymer modified with an alkyl maleate graft, 0.5 wt% of a polyorganosiloxane elastomer, 0.1 wt% of an antioxidant, and 79.4 wt% of an ethylene-octene copolymer. The grafting ratio of the alkyl maleate in the ethylene-vinyl acetate copolymer modified with the alkyl maleate graft is 30 wt%.

[0078] The preparation method of the anti-fog high-barrier matt film of this embodiment is the same as that of Example 1.

[0079] Comparative Example 1

[0080] This comparative example provides an anti-fog high-barrier matt film with a total thickness of 18 μm, including a 2.0 μm anti-fog barrier matt layer, a 14.2 μm core layer and a 1.8 μm primer layer.

[0081] The anti-fog barrier matt layer comprises 43 wt% high-density polyethylene, 1 wt% propylene-norbornene copolymer grafted with N-hexadecyldiethanolamine monoacrylate, 1.2 wt% homopolypropylene grafted with maleic anhydride, and 54.8 wt% random copolymer polypropylene. The graft ratio of N-hexadecyldiethanolamine monoacrylate in the propylene-norbornene copolymer grafted with N-hexadecyldiethanolamine monoacrylate is 1.5 wt%.

[0082] The core layer comprises 99 wt% homopolypropylene having an isotacticity of 95% and a melt index of 3.6 g / 10 min and 1 wt% antistatic agent.

[0083] The primer layer comprises 12 wt% of a propylene-butene copolymer, 3.5 wt% of an ethylene-vinyl acetate copolymer modified with an alkyl maleate graft, 0.5 wt% of a polyorganosiloxane elastomer, 0.1 wt% of an antioxidant, and 83.9 wt% of an ethylene-octene copolymer. The grafting ratio of the alkyl maleate in the ethylene-vinyl acetate copolymer modified with the alkyl maleate graft is 20 wt%.

[0084] The preparation method of the anti-fog high barrier matt film of this comparative example is the same as that of Example 1.

[0085] Comparative Example 2

[0086] This comparative example provides an anti-fog high-barrier matt film with a total thickness of 18 μm, including a 2.0 μm anti-fog barrier matt layer, a 14.2 μm core layer and a 1.8 μm primer layer.

[0087] The anti-fog barrier matt layer comprises 43wt% high-density polyethylene, 15wt% propylene-norbornene copolymer grafted with N-hexadecyldiethanolamine monoacrylate, 1.2wt% homopolypropylene grafted with maleic anhydride, and 40.8wt% random copolymer polypropylene. The graft ratio of N-hexadecyldiethanolamine monoacrylate in the propylene-norbornene copolymer grafted with N-hexadecyldiethanolamine monoacrylate is 1.5wt%.

[0088] The core layer comprises 99 wt% homopolypropylene having an isotacticity of 95% and a melt index of 3.6 g / 10 min and 1 wt% antistatic agent.

[0089] The primer layer comprises 12 wt% of a propylene-butene copolymer, 3.5 wt% of an ethylene-vinyl acetate copolymer modified with an alkyl maleate graft, 0.5 wt% of a polyorganosiloxane elastomer, 0.1 wt% of an antioxidant, and 83.9 wt% of an ethylene-octene copolymer. The grafting ratio of the alkyl maleate in the ethylene-vinyl acetate copolymer modified with the alkyl maleate graft is 20 wt%.

[0090] The preparation method of the anti-fog high barrier matt film of this comparative example is the same as that of Example 1.

[0091] Comparative Example 3

[0092] This comparative example provides an anti-fog high-barrier matt film with a total thickness of 18 μm, including a 2.0 μm anti-fog barrier matt layer, a 14.2 μm core layer and a 1.8 μm primer layer.

[0093] The anti-fog barrier matt layer comprises 43 wt% high-density polyethylene, 7 wt% propylene-norbornene copolymer grafted with N-hexadecyldiethanolamine monoacrylate, 1.2 wt% homopolypropylene grafted with maleic anhydride, and 48.8 wt% random copolymer polypropylene. The grafting ratio of N-hexadecyldiethanolamine monoacrylate in the propylene-norbornene copolymer grafted with N-hexadecyldiethanolamine monoacrylate is 0.5 wt%.

[0094] The core layer comprises 99 wt% homopolypropylene having an isotacticity of 95% and a melt index of 3.6 g / 10 min and 1 wt% antistatic agent.

[0095] The primer layer comprises 12 wt% of a propylene-butene copolymer, 3.5 wt% of an ethylene-vinyl acetate copolymer modified with an alkyl maleate graft, 0.5 wt% of a polyorganosiloxane elastomer, 0.1 wt% of an antioxidant, and 83.9 wt% of an ethylene-octene copolymer. The grafting ratio of the alkyl maleate in the ethylene-vinyl acetate copolymer modified with the alkyl maleate graft is 20 wt%.

[0096] The preparation method of the anti-fog high barrier matt film of this comparative example is the same as that of Example 1.

[0097] Comparative Example 4

[0098] This comparative example provides an anti-fog high-barrier matt film with a total thickness of 18 μm, including a 2.0 μm anti-fog barrier matt layer, a 14.2 μm core layer and a 1.8 μm primer layer.

[0099] The anti-fog barrier matt layer comprises 43 wt% high-density polyethylene, 7 wt% propylene-norbornene copolymer grafted with N-hexadecyldiethanolamine monoacrylate, 1.2 wt% homopolypropylene grafted with maleic anhydride, and 48.8 wt% random copolymer polypropylene. The grafting ratio of N-hexadecyldiethanolamine monoacrylate in the propylene-norbornene copolymer grafted with N-hexadecyldiethanolamine monoacrylate is 4 wt%.

[0100] The core layer comprises 99 wt% homopolypropylene having an isotacticity of 95% and a melt index of 3.6 g / 10 min and 1 wt% antistatic agent.

[0101] The primer layer comprises 12 wt% of a propylene-butene copolymer, 3.5 wt% of an ethylene-vinyl acetate copolymer modified with an alkyl maleate graft, 0.5 wt% of a polyorganosiloxane elastomer, 0.1 wt% of an antioxidant, and 83.9 wt% of an ethylene-octene copolymer. The grafting ratio of the alkyl maleate in the ethylene-vinyl acetate copolymer modified with the alkyl maleate graft is 20 wt%.

[0102] The preparation method of the anti-fog high barrier matt film of this comparative example is the same as that of Example 1.

[0103] Comparative Example 5

[0104] This comparative example provides an anti-fog high-barrier matt film with a total thickness of 18 μm, including a 2.0 μm anti-fog barrier matt layer, a 14.2 μm core layer and a 1.8 μm primer layer.

[0105] The anti-fog barrier matt layer comprises 43 wt% high-density polyethylene, 7 wt% propylene-norbornene copolymer grafted with N-hexadecyldiethanolamine monoacrylate, 1.2 wt% homopolypropylene grafted with maleic anhydride, and 48.8 wt% random copolymer polypropylene. The graft ratio of N-hexadecyldiethanolamine monoacrylate in the propylene-norbornene copolymer grafted with N-hexadecyldiethanolamine monoacrylate is 1.5 wt%.

[0106] The core layer comprises 99 wt% homopolypropylene having an isotacticity of 95% and a melt index of 3.6 g / 10 min and 1 wt% antistatic agent.

[0107] The primer layer includes 12 wt% of propylene-butene copolymer, 0.5 wt% of polyorganosiloxane elastomer, 0.1 wt% of antioxidant and 87.4 wt% of ethylene-octene copolymer.

[0108] The preparation method of the anti-fog high barrier matt film of this comparative example is the same as that of Example 1.

[0109] Comparative Example 6

[0110] This comparative example provides an anti-fog high-barrier matt film with a total thickness of 18 μm, including a 2.0 μm anti-fog barrier matt layer, a 14.2 μm core layer and a 1.8 μm primer layer.

[0111] The anti-fog barrier matt layer comprises 43 wt% high-density polyethylene, 7 wt% propylene-norbornene copolymer grafted with N-hexadecyldiethanolamine monoacrylate, 1.2 wt% homopolypropylene grafted with maleic anhydride, and 48.8 wt% random copolymer polypropylene. The graft ratio of N-hexadecyldiethanolamine monoacrylate in the propylene-norbornene copolymer grafted with N-hexadecyldiethanolamine monoacrylate is 1.5 wt%.

[0112] The core layer comprises 99 wt% homopolypropylene having an isotacticity of 95% and a melt index of 3.6 g / 10 min and 1 wt% antistatic agent.

[0113] The primer layer comprises 12 wt% of a propylene-butene copolymer, 8 wt% of an ethylene-vinyl acetate copolymer modified with an alkyl maleate graft, 0.5 wt% of a polyorganosiloxane elastomer, 0.1 wt% of an antioxidant, and 79.4 wt% of an ethylene-octene copolymer. The grafting ratio of the alkyl maleate in the ethylene-vinyl acetate copolymer modified with the alkyl maleate graft is 20 wt%.

[0114] The preparation method of the anti-fog high barrier matt film of this comparative example is the same as that of Example 1.

[0115] Comparative Example 7

[0116] This comparative example provides an anti-fog high-barrier matt film with a total thickness of 18 μm, including a 2.0 μm anti-fog barrier matt layer, a 14.2 μm core layer and a 1.8 μm primer layer.

[0117] The anti-fog barrier matt layer comprises 43 wt% high-density polyethylene, 7 wt% propylene-norbornene copolymer grafted with N-hexadecyldiethanolamine monoacrylate, 1.2 wt% homopolypropylene grafted with maleic anhydride, and 48.8 wt% random copolymer polypropylene. The graft ratio of N-hexadecyldiethanolamine monoacrylate in the propylene-norbornene copolymer grafted with N-hexadecyldiethanolamine monoacrylate is 1.5 wt%.

[0118] The core layer comprises 99 wt% homopolypropylene having an isotacticity of 95% and a melt index of 3.6 g / 10 min and 1 wt% antistatic agent.

[0119] The primer layer comprises 12 wt% of a propylene-butene copolymer, 3.5 wt% of an ethylene-vinyl acetate copolymer modified with an alkyl maleate graft, 0.5 wt% of a polyorganosiloxane elastomer, 0.1 wt% of an antioxidant, and 83.9 wt% of an ethylene-octene copolymer. The grafting ratio of the alkyl maleate in the ethylene-vinyl acetate copolymer modified with the alkyl maleate graft is 5 wt%.

[0120] The preparation method of the anti-fog high barrier matt film of this comparative example is the same as that of Example 1.

[0121] Comparative Example 8

[0122] This comparative example provides an anti-fog high-barrier matt film with a total thickness of 18 μm, including a 2.0 μm anti-fog barrier matt layer, a 14.2 μm core layer and a 1.8 μm primer layer.

[0123] The anti-fog barrier matt layer comprises 43 wt% high-density polyethylene, 7 wt% propylene-norbornene copolymer grafted with N-hexadecyldiethanolamine monoacrylate, 1.2 wt% homopolypropylene grafted with maleic anhydride, and 48.8 wt% random copolymer polypropylene. The graft ratio of N-hexadecyldiethanolamine monoacrylate in the propylene-norbornene copolymer grafted with N-hexadecyldiethanolamine monoacrylate is 1.5 wt%.

[0124] The core layer comprises 99 wt% homopolypropylene having an isotacticity of 95% and a melt index of 3.6 g / 10 min and 1 wt% antistatic agent.

[0125] The primer layer comprises 12 wt% of a propylene-butene copolymer, 3.5 wt% of an ethylene-vinyl acetate copolymer modified with an alkyl maleate graft, 0.5 wt% of a polyorganosiloxane elastomer, 0.1 wt% of an antioxidant, and 83.9 wt% of an ethylene-octene copolymer. The grafting ratio of the alkyl maleate in the ethylene-vinyl acetate copolymer modified with the alkyl maleate graft is 40 wt%.

[0126] The preparation method of the anti-fog high barrier matt film of this comparative example is the same as that of Example 1.

[0127] Comparative Example 9

[0128] This comparative example provides an anti-fog high-barrier matt film with a total thickness of 18 μm, including a 2.0 μm anti-fog barrier matt layer, a 14.2 μm core layer and a 1.8 μm primer layer.

[0129] The anti-fog barrier matt layer consists of 43 wt% high-density polyethylene, 7 wt% N-octyldiethanolamine acrylate-grafted modified propylene-norbornene copolymer, 1.2 wt% maleic anhydride-grafted homopolypropylene, and 48.8 wt% random copolymer polypropylene. The grafting ratio of N-octyldiethanolamine acrylate-grafted modified propylene-norbornene copolymer is 1.5 wt%.

[0130] The core layer comprises 99 wt% homopolypropylene having an isotacticity of 95% and a melt index of 3.6 g / 10 min and 1 wt% antistatic agent.

[0131] The primer layer comprises 12 wt% of a propylene-butene copolymer, 3.5 wt% of an ethylene-vinyl acetate copolymer modified with an alkyl maleate graft, 0.5 wt% of a polyorganosiloxane elastomer, 0.1 wt% of an antioxidant, and 83.9 wt% of an ethylene-octene copolymer. The grafting ratio of the alkyl maleate in the ethylene-vinyl acetate copolymer modified with the alkyl maleate graft is 20 wt%.

[0132] The preparation method of the anti-fog high barrier matt film of this comparative example is the same as that of Example 1.

[0133] Comparative Example 10

[0134] This comparative example provides an anti-fog high-barrier matt film with a total thickness of 18 μm, including a 2.0 μm anti-fog barrier matt layer, a 14.2 μm core layer and a 1.8 μm primer layer.

[0135] The anti-fog barrier matt layer comprises 43 wt% high-density polyethylene, 7 wt% propylene-norbornene copolymer grafted with N-eicosyldiethanolamine monoacrylate, 1.2 wt% homopolypropylene grafted with maleic anhydride, and 48.8 wt% random copolymer polypropylene. The grafting ratio of N-eicosyldiethanolamine monoacrylate in the propylene-norbornene copolymer grafted with N-eicosyldiethanolamine monoacrylate is 1.5 wt%.

[0136] The core layer comprises 99 wt% homopolypropylene having an isotacticity of 95% and a melt index of 3.6 g / 10 min and 1 wt% antistatic agent.

[0137] The primer layer comprises 12 wt% of a propylene-butene copolymer, 3.5 wt% of an ethylene-vinyl acetate copolymer modified with an alkyl maleate graft, 0.5 wt% of a polyorganosiloxane elastomer, 0.1 wt% of an antioxidant, and 83.9 wt% of an ethylene-octene copolymer. The grafting ratio of the alkyl maleate in the ethylene-vinyl acetate copolymer modified with the alkyl maleate graft is 20 wt%.

[0138] The preparation method of the anti-fog high barrier matt film of this comparative example is the same as that of Example 1.

[0139] Performance Testing

[0140] The anti-fog high-barrier matte films prepared in Examples 1 to 3 and Comparative Examples 1 to 10 were coated on printed parts, and the performance of the anti-fog high-barrier matte films and the coated printed parts was tested. The test results are shown in Table 2.

[0141] Among them, the physical properties and their test methods are as follows:

[0142] Anti-fog performance evaluation: The anti-fog performance of the film is tested according to GB / T31726-2015, specifically the cold mist method and the water bath hot mist method; among them, level 1 represents completely transparent without water droplets, level 2 represents good transparency with a small amount of uneven large water droplets, level 3 represents basically transparent with more water droplets, level 4 represents translucent with many small water droplets, and level 5 represents completely opaque.

[0143] The gloss test is carried out according to GB / T8807-1988, and the haze test is carried out according to GB / T2410-2008.

[0144] Evaluation of the bonding strength between the primer layer and the hot-melt adhesive layer: EVA hot-melt adhesive (VA content of 18 wt %, melt index of 15 g / 10 min) was coated on the surface of the primer layer with a coating thickness of 5 μm. After coating, a layer peeling test was performed using 3M adhesive tape to observe whether the EVA hot-melt adhesive layer peeled off.

[0145] Evaluation of the peel strength (N / 15mm) between a film coated with a hot-melt adhesive and a printed material: Measured according to GB / T8808 (Method A), the unit is N / 15mm. The laminated digital printed material used in this invention is a 250g white card with a black spot color print (the ink contains 0.5wt% silicone oil). Laminated at 100°C, 10 MPa, and 20 m / min to produce a laminated printed material. The laminated printed material was then aged at 45°C and 80% humidity for 5 hours. The peel strength was measured at a constant temperature and humidity of 25°C and 80%. It should be noted that peel strength testing is typically conducted at a humidity of 45-55%. However, this invention considers humid application environments, controlling the humidity to 80% to evaluate the peel performance of the film in this high-humidity environment.

[0146] Table 2 - Test results of anti-fog high barrier matte film and laminated printed parts

[0147]

[0148] As can be seen from Table 2, the films prepared in Examples 1-3 have excellent anti-fog properties, with both cold anti-fog and hot anti-fog properties reaching Level 1. The primer layer and the hot-melt adhesive layer have strong bonding strength, and no peeling occurred between the primer layer and the hot-melt adhesive layer under the test conditions. Even under humid conditions, the films have high peel strength and are suitable for use in humid conditions. In addition, when preparing the films in Examples 1-3, the production was smooth and there was no delamination.

[0149] Compared with Example 2, the cold and hot anti-fog properties of Comparative Example 1 dropped to Level 4. The bonding strength between the primer layer and the hot-melt adhesive layer was reduced, resulting in chunky tearing during peeling. Under humid conditions, the peel strength between the hot-melt adhesive-coated film and the printed material was low. This is because the content of the propylene-norbornene copolymer grafted with N-hexadecyldiethanolamine acrylate is too low to effectively improve the film's anti-fog performance or barrier properties, thus failing to synergize with the primer layer to improve the bonding strength between the primer layer and the hot-melt adhesive layer.

[0150] Compared with Example 2, Comparative Example 2 exhibited both cold and hot anti-fog properties that dropped to Level 2, resulting in poor production flow and delamination during production. This was due to the excessive content of the propylene-norbornene copolymer grafted with N-hexadecyldiethanolamine monoacrylate. While this improved anti-fog performance, its poor dispersibility in the anti-fog barrier matte layer resulted in poor anti-fog uniformity, which compromised overall anti-fog performance. Furthermore, excessive addition of the propylene-norbornene copolymer grafted with N-hexadecyldiethanolamine monoacrylate resulted in a significant difference in viscosity between the matte layer and the core layer, leading to delamination during production.

[0151] Compared with Example 2, the cold and hot anti-fog properties of Comparative Example 3 dropped to Level 4. The bonding strength between the primer layer and the hot-melt adhesive layer was reduced, resulting in chunky tearing during peeling. The peel strength between the film coated with the hot-melt adhesive layer and the printed material was low under humid conditions. This is due to the low grafting rate of the propylene-norbornene copolymer modified with N-n-hexadecyldiethanolamine acrylate, resulting in too few hydrophilic groups and ineffective anti-fog performance. Furthermore, a low grafting rate also prevents the propylene-norbornene copolymer from providing a barrier effect, thus failing to synergize with the primer layer to improve the bonding strength between the primer layer and the hot-melt adhesive layer.

[0152] Compared with Example 2, the cold anti-fog properties and hot anti-fog properties of Comparative Example 4 are both reduced to level 2. This is because the grafting rate of the propylene-norbornene copolymer grafted with N-n-hexadecyldiethanolamine acrylate is too high, resulting in too strong intermolecular forces such as hydrogen bonds between the molecules of the propylene-norbornene copolymer itself, forming a physical cross-linked structure, which cannot be evenly dispersed in the matte layer, and thus cannot effectively improve the anti-fog performance of the film.

[0153] In Comparative Example 5, compared with Example 2, the bonding strength between the primer layer and the hot-melt adhesive layer is reduced, and block-shaped tearing occurs during peeling. The peeling strength between the film coated with the hot-melt adhesive and the printed part is low under humid conditions. This is because the alkyl maleate grafted modified ethylene-vinyl acetate copolymer is not added to the primer layer, resulting in insufficient bonding strength between the primer layer and the hot-melt adhesive layer.

[0154] Comparative Example 6 had poor production smoothness and roller sticking during production compared to Example 2. This was because the content of the alkyl maleate grafted modified ethylene-vinyl acetate copolymer was too high, which increased the viscosity of the primer layer and caused roller sticking during production.

[0155] In Comparative Example 7, compared with Example 2, the bonding strength between the primer layer and the hot-melt adhesive layer is reduced, and block-shaped tearing occurs during peeling. The peeling strength between the film coated with the hot-melt adhesive and the printed part is low under humid conditions. This is because the grafting rate of the ethylene-vinyl acetate copolymer modified by the alkyl maleate grafting is too low, resulting in a low content of polar ester groups, which cannot cooperate with the matte layer to ensure the bonding strength between the primer layer and the hot-melt adhesive layer, especially in a humid environment.

[0156] Compared with Example 2, Comparative Example 8 exhibited poor production smoothness and roller sticking during production. This was due to the excessively high grafting rate of the alkyl maleate-grafted ethylene-vinyl acetate copolymer, which reduced the thermal stability of the alkyl maleate-grafted ethylene-vinyl acetate copolymer itself and caused thermal decomposition at the production process temperature, resulting in excessive adhesion of the primer layer and roller sticking.

[0157] Compared with Example 2, the cold anti-fog and hot anti-fog properties of Comparative Example 9 are both reduced to level 4. This is because the alkyl chain of the N-(n-alkyl) diethanolamine acrylate grafted modified propylene-norbornene copolymer is too short, and its hydrophilic chain segment is difficult to move away from the low-polarity resin matrix and toward the outside of the film, thereby failing to effectively improve the anti-fog performance of the film.

[0158] Compared with Example 2, the cold anti-fog property and the hot anti-fog property of Comparative Example 10 are both reduced to level 3. This is because the alkyl chain of the N-(n-alkyl) diethanolamine acrylate grafted modified propylene-norbornene copolymer is too long, which will lead to excessive steric hindrance. Its hydrophilic chain segment cannot be effectively spread on the surface of the film, and thus cannot effectively improve the anti-fog performance of the film.

[0159] In summary, the present invention achieves good anti-fog performance and certain barrier properties by adding N-(n-alkyl) diethanolamine acrylate grafted modified propylene-norbornene copolymer to the anti-fog barrier matting layer and controlling the appropriate grafting ratio and alkyl chain length. Maleic anhydride grafted homopolypropylene is also added to uniformly disperse the N-(n-alkyl) diethanolamine acrylate grafted modified propylene-norbornene copolymer in the anti-fog barrier matting layer, while enhancing the bonding between the anti-fog barrier matting layer (with a higher polarity) and the core layer, thus preventing delamination during production and use. Alkyl maleate grafted modified ethylene-vinyl acetate copolymer is added to the primer layer and controlled to an appropriate grafting ratio to improve the bonding between the primer layer and the hot melt adhesive layer. Propylene-butylene copolymer is added to the primer layer to improve the interfacial compatibility between the primer layer and the core layer. The synergistic effect of the differential functions of the anti-fog barrier matting layer and the primer layer enhances the bonding between the primer layer and the hot melt adhesive in humid environments.

[0160] The above-described embodiments merely illustrate several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, and all such variations and improvements fall within the scope of protection of the present invention.

Claims

1. An anti-fog high barrier matte film, characterized in that: It includes an anti-fog barrier matt layer, a core layer and a base coating layer arranged in sequence; The anti-fog barrier matt layer is composed of random copolymerized polypropylene, 40-46 wt% high-density polyethylene, 4-10 wt% N-(n-alkyl) diethanolamine acrylate grafted modified propylene-norbornene copolymer, and 1-2 wt% maleic anhydride grafted homopolypropylene; wherein the random copolymerized polypropylene is selected from one or both of ethylene-propylene copolymerized polypropylene and ethylene-propylene-butylene copolymerized polypropylene; the N-(n-alkyl) diethanolamine acrylate grafted modified propylene-norbornene copolymer is formed by grafting N-(n-alkyl) diethanolamine acrylate grafted modified propylene-norbornene copolymer; the molar content of norbornene in the propylene-norbornene copolymer is 25-28%, the grafting rate of N-(n-alkyl) diethanolamine acrylate grafted modified propylene-norbornene copolymer is 1-2.5%, and n is any integer between 14 and 18; The core layer comprises homopolypropylene; The primer layer is composed of ethylene-octene copolymer, 10-15wt% propylene-butene copolymer, 2-5wt% alkyl maleate grafted modified ethylene-vinyl acetate copolymer, 0.5-1wt% polysiloxane elastomer and 0.1-0.3wt% antioxidant; wherein the alkyl maleate grafted modified ethylene-vinyl acetate copolymer is modified from alkyl maleate grafted ethylene-vinyl acetate copolymer, the alkyl maleate is any one of di-n-octyl maleate or di-n-butyl maleate, the melt index of the ethylene-vinyl acetate copolymer is 20-25g / 10min; and the grafting rate of alkyl maleate in the alkyl maleate grafted modified ethylene-vinyl acetate copolymer is 12-30%.

2. The anti-fog high barrier matte film according to claim 1, characterized in that: At 230° C. and a load of 2.16 kg, the melt index of the N-(n-alkyl)diethanolamine acrylate graft-modified propylene-norbornene copolymer is 5-10 g / 10 min.

3. The anti-fog high barrier matte film according to claim 2, characterized in that: At 230° C. and a load of 2.16 kg, the melt index of the random copolymer polypropylene is 6-10 g / 10 min; at 190° C. and a load of 2.16 kg, the melt index of the high-density polyethylene is 9-20 g / 10 min.

4. The anti-fog high barrier matte film according to claim 1, characterized in that: The homopolypropylene has an isotacticity of 90-99% and a melt index of 3.5-3.8 g / 10 min at 230° C. and a load of 2.16 kg.

5. The anti-fog high barrier matte film according to claim 1, characterized in that: At 190° C. and a load of 2.16 kg, the melt index of the alkyl maleate grafted modified ethylene-vinyl acetate copolymer is 26-28 g / 10 min; the melting point of the alkyl maleate grafted modified ethylene-vinyl acetate copolymer is 80-90° C.

6. The anti-fog high barrier matte film according to claim 1, characterized in that: The melting point of the ethylene-octene copolymer is 75-95°C, and the melting point of the propylene-butene copolymer is 80-95°C.

7. The anti-fog high barrier matte film according to claim 1, characterized in that: The particle size D90 of the polyorganosiloxane elastomer is 3-5 μm.

8. A method for preparing the anti-fog high barrier matte film according to any one of claims 1 to 7, characterized in that: The steps include: The component raw materials of the anti-fog barrier matt layer, the core layer, and the primer layer are respectively put into a batching unit, and after being measured, they are co-extruded through an extruder, merged in a three-layer die after passing through a flow channel distributor, and then cooled by a chilled roller to form a thick sheet. The thick sheet is biaxially stretched by a stretching roller to form a film, and the film is cooled and simultaneously thickness-controlled by a trimming machine, and then corona and / or flame treated to obtain the anti-fog high-barrier matt film.

9. The method for preparing an anti-fog high-barrier matte film according to claim 8, characterized in that: The surface of the primer feeding trough of the extruder and the surface of the stretching roller used in the biaxial stretching are provided with Teflon coating.

Images