PET / PE composite film corona treatment process and equipment

Abstract

The invention discloses a PET / PE composite film corona treatment process and equipment, in PET / PE composite film corona treatment, gas environment control is added, and gas components and states are accurately regulated and controlled according to the type of a non-polar base material in a composite structure and subsequent composite requirements, so that directional modification of the surface activity of the base material is realized; and the interlayer bonding stability is ensured. Strong oxidizing particles generated by oxygen ionization are used, carboxyl is efficiently introduced, the compatibility with polyurethane adhesive is improved, polyurethane adhesive is adapted, the surface tension of the treated PET / PE composite film can be improved to 38-45 dynes from 28-32 dynes, the adaptation requirement of the adhesive is met, the interlayer peeling strength is improved by 2-5 times, no layering is still generated after high-temperature cooking, and the service life of the PET / PE composite film is prolonged. Corona treatment only acts on the surface of the base material, the mechanical property and chemical stability of the base material are not damaged, meanwhile, good heat sealing performance is achieved, and follow-up processing is not affected.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of film processing, in particular to a PET / PE composite film corona treatment process and equipment. BACKGROUND

[0002] The film corona device is mainly used for surface treatment of plastic film products.

[0003] The essence of corona treatment is to ionize gas to produce plasma through a high-frequency high-voltage electric field, and active particles (such as free radicals and ions) in the plasma bombard the surface of the film to achieve surface etching and polarity group introduction.

[0004] Composite films are usually composed of multiple layers of different materials (such as LLDPE / aluminum foil, PET / PE, nylon / PE, etc.), and there are two key problems that must be solved by corona treatment: 1. Strong inertness of the substrate surface, which cannot be effectively bonded The composite process relies on adhesives to bond two or more films into a whole, but the molecular structure of PE, PP and other polyolefin substrates is stable, and the surface tension is extremely low. The adhesive cannot spread and penetrate on the surface, and direct compounding will result in insufficient interlayer peeling strength, which is easy to delaminate in subsequent processing or use.

[0005] 2. Large difference in surface performance of different materials, poor adaptability The composite layer often contains polar materials (such as PET and nylon) and non-polar materials (such as PE and PP), and the surface energy difference between the two is huge. Even if special adhesives are used, the low activity of non-polar layers will become a "short board" for bonding, resulting in unstable performance of the composite whole.

[0006] But even if the corona treatment, the above shortcomings still have some defects, we hope to realize the directional modification of the surface activity of the substrate, and ensure the stable bonding between the layers.

[0007] Now a new technical solution is proposed to solve the above problems. SUMMARY

[0008] The purpose of the present application is to provide a PET / PE composite film corona treatment process and equipment to solve any of the problems raised in the background art.

[0009] To achieve the above purpose, the present application provides the following technical solution: 1. A PET / PE composite film corona treatment process, comprising the following steps: S1, preparing an environmental gas, drying and filtering the environmental gas; S2, preparing a composite film corona discharge cavity, and inputting the environmental gas into the composite film corona discharge cavity; S3, the composite film is subjected to corona treatment.

[0010] As a further technical solution of the present application, the environmental gas is oxygen-rich mixed gas, the oxygen concentration is 30%-60%, and the oxygen purity is ≥99.5%.

[0011] As a further technical solution of the present application, in step S2, the pressure of the environmental gas input into the composite film corona discharge cavity is 0.11-0.13 MPa.

[0012] As a further technical solution of the present application, in step S1, the humidity of the dried environmental gas is 25%-30%.

[0013] As a further technical solution of the present application, in step S1, the environmental gas is dried by a freeze dryer and filtered by a filter.

[0014] As a further technical solution of the present application, in step S2, the pressure in the composite film corona discharge cavity is higher than the outside by 5-8 Pa.

[0015] A PET / PE composite film corona treatment device comprises a closed composite film corona discharge cavity, an electrode assembly and a corona roller arranged in the composite film corona discharge cavity, and an air inlet valve for inputting dried and filtered environmental gas.

[0016] As a further technical solution of the present application, a front-end environmental gas preparation device is included, which comprises an air filter, a freeze dryer, an oxygen generator, a static mixer and a gas buffer tank, and the gas buffer tank is connected with the composite film corona discharge cavity.

[0017] Compared with the prior art, the present application has the following advantages: This invention provides a corona treatment process and equipment for PET / PE composite films. In the corona treatment of PET / PE composite films, gas environment control is creatively incorporated. Its core is to precisely control the gas composition and state according to the type of non-polar substrate in the composite structure and the subsequent composite requirements, so as to achieve directional modification of the surface activity of the substrate and ensure stable interlayer adhesion. The ambient gas is an oxygen-rich mixture. Different gases ionize under high frequency and high pressure, producing completely different active particles. These active particles actively react with molecules on the film surface, "breaking" the original chemical bonds and then "attaching" their own atoms or groups. The strong oxidizing particles generated by oxygen ionization efficiently introduce carboxyl groups, improving compatibility with polyurethane adhesives and making the film compatible with polyurethane adhesives. The surface tension of the treated PET / PE composite film can be increased from 28-32 dynes to 38-45 dynes, meeting the adhesive compatibility requirements. The interlayer peel strength is increased by 2-5 times, and there is no delamination after high-temperature cooking. The corona treatment only acts on the substrate surface and does not damage the mechanical properties and chemical stability of the substrate itself. It also has good heat-sealing performance and does not affect subsequent processing. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of a PET / PE composite film corona treatment device according to the present invention.

[0019] In the figure: 10, composite film corona discharge chamber; 20, electrode assembly; 30, corona roller; 40, air inlet valve; 50, exhaust pipe. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] This invention provides a corona treatment process for PET / PE composite films, comprising the following steps: S1. Prepare the ambient gas and dry and filter it. S2. Prepare the composite thin film corona discharge chamber 10 and introduce ambient gas into the composite thin film corona discharge chamber 10. S3. The composite film is subjected to corona treatment.

[0022] In this invention, gas environment control is creatively incorporated into the corona treatment of PET / PE composite films. The core of this method is to precisely control the gas composition and state based on the type of non-polar substrate in the composite structure and subsequent lamination requirements. This achieves directional modification of the substrate surface activity, ensuring stable interlayer adhesion. In the embodiments, the ambient gas is an oxygen-rich mixed gas. Different gases ionize under high frequency and high pressure, producing completely different active particles. These active particles actively react with molecules on the film surface, "breaking" the original chemical bonds and then "attaching" their own atoms or groups. The strong oxidizing particles generated by oxygen ionization efficiently introduce carboxyl groups, improving compatibility with polyurethane adhesives and adapting to polyurethane adhesives. The surface tension of the treated PET / PE composite film can be increased from 28-32 dynes to 38-45 dynes, meeting the adhesive compatibility requirements. The interlayer peel strength is increased by 2-5 times, and there is no delamination after high-temperature cooking. The corona treatment only acts on the substrate surface and does not damage the mechanical properties and chemical stability of the substrate itself. It also possesses good heat-sealing performance and does not affect subsequent processing.

[0023] After filtration, the ambient gas is cleaned to remove oil and dust, preventing impurities from adhering to the substrate surface and forming composite defects (such as bubbles and spots). Strict control of gas humidity is necessary, requiring a drying process. The humidity of the dried ambient gas should be 25%-30% to avoid moisture causing unstable discharge or water stains on the film surface, and to prevent residual moisture from causing adhesive delamination. In some embodiments of this invention, the ambient gas is dried using a freeze dryer and then filtered.

[0024] In some embodiments of the present invention, the oxygen concentration of the oxygen-enriched mixed gas is 30%-60%, and the oxygen purity is ≥99.5%, so as to avoid impurities affecting the discharge.

[0025] As a further technical solution of the present invention, in step S2, the pressure of the ambient gas input into the composite thin film corona discharge cavity 10 is 0.11-0.13 MPa.

[0026] As a further technical solution of the present invention, in step S2, the pressure inside the composite thin film corona discharge cavity 10 is 5Pa-8Pa higher than that outside, to prevent outside air (including high humidity and impurities) from seeping in and to ensure the stability of the gas composition.

[0027] A corona treatment device for PET / PE composite films, such as Figure 1 As shown, it includes a sealed composite film corona discharge chamber 10, an electrode assembly 20 and a corona roller 30 disposed in the composite film corona discharge chamber 10, and an air inlet valve 40, which is used to input the dried and filtered ambient gas. It also includes an exhaust pipe 50, and an exhaust flow valve is provided at the exhaust pipe 50 to control the exhaust volume and ensure the pressure inside the chamber.

[0028] As a further technical solution of the present invention, a front-end environmental gas preparation device is included. This device comprises an air filter, a freeze dryer, an oxygen generator, a static mixer, and a gas buffer tank. The gas buffer tank is connected to the composite thin-film corona discharge chamber 10. In preparing the oxygen-enriched mixed gas, outside air first enters the air filter to remove dust and particulate matter, then passes through the freeze dryer to reduce humidity, preventing moisture from affecting the molecular sieve adsorption efficiency, finally obtaining clean and dry compressed air. The air then enters the oxygen generator, which outputs gaseous oxygen with a purity of 93% ± 2%. High-concentration oxygen and a base gas are mixed as needed, and the two gases are thoroughly mixed in the static mixer to form a uniformly concentrated oxygen-enriched mixed gas.

[0029] Although the present invention has been described in detail with reference to the above embodiments, it will be apparent to those skilled in the art that various changes or modifications can be made to the invention without departing from the principles and spirit of the invention as defined by the claims. Therefore, the detailed description of the embodiments in this disclosure is for illustrative purposes only and is not intended to limit the invention; rather, the scope of protection is defined by the content of the claims.

[0030] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A process for the corona treatment of a PET / PE composite film, characterized in that, The method comprises the following steps: S1, preparing an environmental gas, and drying and filtering the environmental gas; S2, preparing a composite film corona discharge chamber (10), and inputting the environmental gas into the composite film corona discharge chamber (10); S3, performing corona treatment on the composite film.

2. The PET / PE composite film corona treatment process according to claim 1, characterized in that, The environmental gas is an oxygen-rich mixed gas, the oxygen concentration of which is 30%-60%, and the oxygen purity is ≥99.5%.

3. The PET / PE composite film corona treatment process according to claim 2, characterized in that, In step S2, the pressure of the environmental gas input into the composite film corona discharge chamber (10) is 0.11-0.13 MPa.

4. The PET / PE composite film corona treatment process according to claim 1, characterized in that, In step S1, the humidity of the dried environmental gas is 25%-30%.

5. The PET / PE composite film corona treatment process according to claim 1, wherein, In step S1, the environmental gas is dried by a freeze dryer and filtered by a filter.

6. The PET / PE composite film corona treatment process according to claim 1, wherein, In step S2, the pressure in the composite film corona discharge chamber (10) is higher than the outside by 5 Pa-8 Pa.

7. A corona treatment device for PET / PE composite films, characterized in that, The method comprises a closed composite film corona discharge chamber (10), an electrode assembly (20) and a corona roller (30) arranged in the composite film corona discharge chamber (10), and an air inlet valve (40) for inputting the dried and filtered environmental gas.

8. The PET / PE composite film corona treatment apparatus according to claim 7, wherein The method comprises a front-end environmental gas preparation device, which comprises an air filter, a freeze dryer, an oxygen generator, a static mixer and a gas buffer tank, and the gas buffer tank is connected with the composite film corona discharge chamber (10).

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