CN-121973526-A - Double-sided corona heat-sealing anti-fog film and preparation method thereof

Abstract

The invention relates to the technical field of film materials, in particular to a double-sided corona heat-sealing anti-fog film and a preparation method thereof, comprising a laminated structure formed by three layers of coextrusion, wherein the laminated structure sequentially comprises a first surface layer, a corona treatment layer and a second surface layer, wherein the first surface layer is made of polypropylene materials; the middle adhesive layer is made of a blend of polypropylene and maleic anhydride grafted polypropylene, the second surface layer is a heat-sealing anti-fog functional layer and is made of a blend of a bio-based reaction compound and an ethylene-vinyl acetate copolymer. The invention can prepare the double-sided corona heat-sealing anti-fog film with good anti-fog performance and higher heat-sealing strength by reasonably designing and optimizing the factors.

Inventors

• LIU XIANG
• ZHOU JIAN
• LIU HUI
• HAN LIYAN

Assignees

• 天津华恒新材料股份有限公司

Dates

Publication Date

20260505

Application Date

20260407

Claims (10)

1. 1. The utility model provides a two-sided corona heat-seal antifog membrane which characterized in that, includes the lamination structure that three-layer co-extrusion formed, lamination structure is in proper order: the first surface layer is a corona treatment layer and is made of polypropylene material; the middle bonding layer is composed of a blend of polypropylene and maleic anhydride grafted polypropylene; The second surface layer is a heat-sealing anti-fog functional layer and is formed by a blend of a bio-based reaction compound and an ethylene-vinyl acetate copolymer; Wherein the bio-based reaction compound is an in-situ esterification/crosslinking product prepared by extrusion granulation of a raw material mixture comprising polyvinyl alcohol, oxidized starch, citric acid and oleic acid through a melt reaction in the presence of a catalyst.
2. 2. The double-sided corona heat-sealing anti-fog film according to claim 1, wherein the mass ratio of the components in the raw material mixture is that polyvinyl alcohol, oxidized starch, citric acid, oleic acid=100, 30, 8 and 15, and the catalyst is p-toluenesulfonic acid, and the dosage of the catalyst is 1.0 wt% of the total mass of the raw material mixture.
3. 3. The double sided corona heat seal anti fog film of claim 1 wherein the blend mass ratio of the bio-based reactive compound to the ethylene vinyl acetate copolymer is 70:30 and the ethylene vinyl acetate copolymer has a vinyl acetate content of 28%.
4. 4. The double sided corona heat seal anti fog film of claim 1 wherein the mass ratio of maleic anhydride grafted polypropylene in the intermediate adhesive layer is 5 wt%.
5. 5. The double sided corona heat sealable anti fog film of claim 1 wherein the film has a total thickness of 50 ± 5 μm, wherein the ratio of the thicknesses of the first skin layer, the intermediate adhesive layer and the second skin layer is 15%: 20%: 65%.
6. 6. A method of making a double sided corona heat seal anti-fog film as defined in any one of claims 1 to 5 comprising the steps of: S1, mixing a raw material mixture containing polyvinyl alcohol, oxidized starch, citric acid, oleic acid and an esterification catalyst, adding the mixture into a double-screw extruder for melt reaction extrusion, and cooling and granulating to obtain a bio-based reaction compound; S2, respectively adding a polypropylene material, a blend of polypropylene and maleic anhydride grafted polypropylene and a blend of the bio-based reaction complex and ethylene-vinyl acetate copolymer into three extruders of a three-layer co-extrusion film blowing unit, and performing co-extrusion, inflation and cooling shaping to obtain a film with an A/B/C three-layer structure, wherein a C layer is formed by the blend of the bio-based reaction complex and the ethylene-vinyl acetate copolymer; s3, carrying out corona treatment on two outer surfaces of the obtained three-layer film, and then carrying out thermalization treatment for 48 hours at 40+/-2 ℃ to obtain the three-layer film.
7. 7. The method according to claim 6, wherein in step S1, the polyvinyl alcohol and oxidized starch are subjected to a drying pretreatment before use to have water contents of less than 1.0 wt% and 5.0% wt%, respectively.
8. 8. The method according to claim 6, wherein in step S1, the temperature of the melt reaction extrusion is controlled to be 120 ℃ in one zone, 140 ℃ in two zones, 160 ℃ in three zones, 155 ℃ in four zones, 150 ℃ in a machine head, and the screw speed is 80-100 rpm.
9. 9. The method according to claim 6, wherein in the step S2, when the three layers are blown by coextrusion, the temperature of each extruder is controlled to be 170-200deg.C for the layer A, 165-195 deg.C for the layer B, 125-145 deg.C for the layer C, and 150-155 deg.C for the coextrusion die.
10. 10. The method according to claim 6, wherein in step S3, the surface tension of the film after corona treatment is greater than 38 dyn/cm.

Description

Double-sided corona heat-sealing anti-fog film and preparation method thereof Technical Field The invention relates to the technical field of film materials, in particular to a double-sided corona heat-sealing anti-fog film and a preparation method thereof. Background The double-sided corona heat-sealing antifogging film is used as a novel packaging film with multiple functions of surface treatment, heat sealing and antifogging, and gradually becomes an important material in the fields of food, fresh, cold chain and daily necessities packaging. The film is modified on the surface of the film by a double-sided corona treatment technology, improves the surface tension and the coating adhesive force, ensures that the film has good hydrophilicity, transparency and processing adaptability, has excellent heat sealing performance, can meet the requirements of bag making, sealing and automatic packaging processes, can effectively inhibit the fogging of the film surface in high humidity, low temperature and other environments, and keeps the inside of the package clearly visible. In the scenes of fresh electronic commerce, cold chain logistics, food processing, retail packaging and the like, the requirements of products on the antifogging property, heat sealing stability, surface processing property and overall transparency of packaging materials are continuously improved, the double-sided corona heat sealing antifogging film can adapt to various packaging structures and production processes, the usability and the appearance effect are considered, and the double-sided corona heat sealing antifogging film is widely applied to the fields of fruits and vegetables, cooked foods, frozen foods, daily necessities, medical packages and the like. Along with the continuous improvement of the requirements of downstream markets on packaging functionality, display performance and processing efficiency, the film material with the integrated performance of double-sided corona, heat sealing and antifogging becomes a key solution for meeting the requirements of modern packaging on high quality and high stability, and the functional packaging film is promoted to develop in more specialized and subdivided directions in various industries. In the prior art, corona breakdown problem easily occurs in the double-sided corona treatment process, if high-frequency high-voltage current is unevenly distributed, pinholes are formed on the film surface, so that the barrier property of the film collapses, meanwhile, reverse corona phenomenon can also occur, serious adhesion occurs after the film is wound, the subsequent processing efficiency is affected, loss is caused, and the corona treatment effect is easily affected by factors such as workshop humidity, film flatness and the like, so that the stability is poor. The film has obvious adhesion trend after printing, especially when the printing ink is not protected by the gloss oil, and the film surface is easy to be damaged, adhered and can not be unfolded when being wound up too tightly or being punched later, and the like, so that the film has more severe requirements on the processing technology. The surface dyne value after corona treatment can be naturally attenuated, and is influenced by storage temperature, humidity and resin physical properties, the attenuation speed is different, and the adhesion of an anti-fog coating and ink can be reduced after attenuation, so that the anti-fog effect and the printing stability of the film are influenced. Disclosure of Invention In order to solve the problems mentioned in the background art, the invention provides a double-sided corona heat-sealing anti-fog film and a preparation method thereof. In order to achieve the above purpose, the present invention adopts the following technical scheme: The invention discloses a double-sided corona heat-sealing anti-fog film, which is of a laminated structure formed by three layers of coextrusion, wherein the structure and the composition of each layer are as follows: The laminated structure sequentially comprises a first surface layer, an intermediate bonding layer and a second surface layer from outside to inside. The first surface layer is a corona treatment layer and is made of polypropylene material, the polypropylene material is homo-polypropylene, the melt index of the polypropylene material is 2.0-3.5g/10min (230 ℃ and 2.16 kg), the middle bonding layer is made of a blend of polypropylene and maleic anhydride grafted polypropylene, wherein the mass ratio of the maleic anhydride grafted polypropylene is 5 wt%, the grafting ratio of the maleic anhydride grafted polypropylene is 0.8-1.2%, the melt index is 3.0-5.0g/10min (230 ℃ and 2.16 kg), the polypropylene material is good in compatibility with the polypropylene material of the first surface layer and the second surface layer, the second surface layer is a heat-sealing anti-fog functional layer, the blend of a biobased reaction compound and an ethylene-