Surface treatment process of self-adhesive label

Abstract

The invention discloses a surface treatment process of a self-adhesive label. The surface treatment process comprises the following steps: S1, carrying out pretreatment; s2, carrying out plasma activation; s3, coating of a functional coating is carried out; s4, gradient curing is carried out; and S5, carrying out surface texture impressing. According to the surface treatment process of the self-adhesive label, the defects that in the prior art, a self-adhesive label surface treatment process is weak in coating binding force, poor in wear resistance and solvent resistance and insufficient in water resistance and antifouling property are overcome, strong binding of a base material and a coating is achieved through multi-step collaborative optimization, and the surface treatment process is simple and convenient to operate. Meanwhile, the wear resistance, solvent resistance and waterproof and antifouling performance of the surface of the label are remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of self-adhesive label processing technology, specifically relating to a surface treatment process for self-adhesive labels. Background Technology

[0002] Self-adhesive labels are widely used in various fields such as food, pharmaceuticals, electronics, and daily chemicals due to their advantages such as ease of use and strong adhesion. With the expansion of application scenarios, the market has placed higher demands on the surface performance of self-adhesive labels, such as abrasion resistance, scratch resistance, solvent resistance, and water and stain resistance.

[0003] Existing surface treatment processes for self-adhesive labels mostly employ single-coat application or simple curing methods, which have the following shortcomings: First, the adhesion between the substrate and the coating is weak, and the coating is prone to peeling off after long-term use; second, the coating has poor abrasion resistance and solvent resistance, and the label surface is easily damaged after contact friction or solvent wiping, affecting information recognition; third, the label surface is mostly a smooth structure, with limited waterproof and stain-resistant performance, making it easy to get stained and difficult to clean. Summary of the Invention

[0004] The main objective of this invention is to provide a surface treatment process for self-adhesive labels that overcomes the shortcomings of existing self-adhesive label surface treatment processes, such as weak coating adhesion, poor wear and solvent resistance, and insufficient waterproof and stain-resistant properties. Through multi-step synergistic optimization, a strong bond between the substrate and the coating is achieved, while significantly improving the wear resistance, solvent resistance, and waterproof and stain-resistant properties of the label surface.

[0005] To achieve the above objectives, the present invention provides a surface treatment process for self-adhesive labels, comprising the following steps: Step S1: Perform pretreatment by selecting PET film as the substrate for self-adhesive labels and sequentially performing alkaline washing, water washing, and vacuum drying on the substrate. Step S2: Perform plasma activation. The pretreated substrate is sent into a low-temperature plasma treatment device. The flow rate of the argon-oxygen mixed gas is monitored in real time by a gas flow sensor to form active groups on the surface of the substrate. Step S3: Apply a functional coating. Prepare a functional coating slurry and apply it using a micro-gravure coating method. During the coating process, the dry film thickness is detected in real time by a laser thickness gauge, and the PLC controller adjusts parameters including the coating roller speed, coating head pressure, and substrate conveying speed to ensure uniform coating thickness. Step S4: Perform gradient curing, first pre-curing at the first temperature for the first time, then raising the temperature to the second temperature for main curing, and finally cooling down to the third temperature for the third time for post-curing; Step S5: Perform surface texture imprinting. The cured substrate is fed into a texture imprinting device, and an imprinting roller with micron-level concave and convex textures is used to form a predetermined texture on the surface of the substrate.

[0006] As a further preferred technical solution to the above technical solution, step S1 is specifically implemented as follows: For alkaline washing, the concentration of sodium hydroxide solution is detected in real time by an online concentration sensor, the processing temperature is detected by a temperature sensor, and the PLC controller dynamically adjusts the solution replenishment and heating power according to the detection data. Alkaline washing removes oil and oxide layers from the surface of the substrate. For water washing, rinse with deionized water until neutral. After water washing, the conductivity of the rinsing water is detected by a conductivity sensor. Once it meets the standard, it enters vacuum drying. For vacuum drying, vacuum and temperature sensors provide real-time feedback data, and the PLC controller regulates the vacuum pump power and heating temperature. The drying time is dynamically adjusted based on the detection results of the substrate moisture content sensor.

[0007] As a further preferred technical solution to the above technical solution, the functional coating slurry includes polyurethane resin, nano silica, organosiloxane coupling agent, polyethylene glycol and deionized water.

[0008] As a further preferred embodiment of the above technical solution, step S5 further includes: Step S6: The finished products after embossing are subjected to performance testing by a fully automated testing system, including water contact angle tester to test hydrophobicity, abrasion tester to test abrasion resistance cycles, solvent resistance tester to test alcohol resistance, and adhesion tester to test coating adhesion. Unqualified products are automatically diverted to the recycling module, and qualified products are collected and stored.

[0009] As a further preferred technical solution to the above technical solution, the predetermined texture in step S5 is a hexagonal honeycomb structure.

[0010] The beneficial effects of this invention are as follows: 1. Strong coating adhesion: Through alkaline washing pretreatment to remove impurities from the substrate surface, plasma activation to introduce active groups, and coupling agent bridging effect, a strong bond is achieved between the substrate and the functional coating.

[0011] 2. Excellent wear and solvent resistance: The reinforcing effect of nano-silica and the full cross-linking of gradient curing improve the wear resistance and alcohol resistance of the label surface.

[0012] 3. Excellent waterproof and stain-resistant properties: The micron-level honeycomb texture structure increases the water contact angle on the label surface, resulting in excellent hydrophobicity. Stains are difficult to adhere to and the label is easy to clean, making it suitable for applications in humid and oily environments.

[0013] 4. High process stability: The parameters of each step are precisely controllable. Processes such as micro-gravure coating, gradient curing, and precision imprinting are used to ensure consistent product performance during mass production. Attached Figure Description

[0014] Figure 1 This is a flowchart illustrating the present invention. Detailed Implementation

[0015] The following description is intended to disclose the present invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art. The basic principles of the invention defined in the following description can be applied to other embodiments, modifications, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the invention.

[0016] In the preferred embodiments of the present invention, those skilled in the art should note that the self-adhesive labels and the like involved in the present invention can be considered as prior art.

[0017] Preferred embodiment.

[0018] like Figure 1 As shown, this invention discloses a surface treatment process for self-adhesive labels, including the following steps: Step S1: Perform pretreatment by selecting PET film as the substrate for self-adhesive labels and sequentially performing alkaline washing, water washing, and vacuum drying on the substrate. Step S2: Plasma activation is performed. The pretreated substrate is fed into a low-temperature plasma treatment device. The flow rate of the argon-oxygen mixed gas (volume ratio 3:1) is monitored in real time using a gas flow sensor, and active groups are formed on the substrate surface. Low-temperature plasma treatment can introduce active groups such as hydroxyl and carboxyl groups on the substrate surface, increasing the surface energy of the substrate and enhancing the adhesion to subsequent coatings. The use of an argon-oxygen mixed gas (volume ratio 3:1) allows for physical etching of the substrate surface with argon, while oxygen introduces more oxygen-containing active groups, forming a moderately roughened active surface without damaging the overall structure of the substrate.

[0019] Step S3: Apply a functional coating. Prepare a functional coating slurry and apply it using a micro-gravure coating method. During the coating process, the dry film thickness is detected in real time by a laser thickness gauge, and the PLC controller adjusts parameters including the coating roller speed, coating head pressure, and substrate conveying speed to ensure uniform coating thickness. Step S4: Perform gradient curing. First, pre-cur at the first temperature (80-90℃) for the first time (20-30 min), then raise the temperature to the second temperature (120-130℃) for the main curing (the second is a recuring process), and finally lower the temperature to the third temperature (60-70℃) for the third time (15-20 min). This can avoid the coating from generating internal stress due to rapid heating and reduce the risk of cracking. Pre-curing can initially fix the coating morphology, the main curing ensures that the coating is fully cross-linked and cured, improving hardness and solvent resistance, and the post-curing can eliminate internal stress and improve the stability of the coating.

[0020] Step S5: Perform surface texture imprinting. The cured substrate is fed into a texture imprinting device and an imprinting roller with micron-level concave and convex textures is used to form a predetermined texture (micron-level honeycomb texture) on the surface of the substrate.

[0021] Specifically, step S1 is implemented as follows: For alkaline washing, the concentration of sodium hydroxide solution is detected in real time by an online concentration sensor, the processing temperature is detected by a temperature sensor, and the PLC controller dynamically adjusts the solution replenishment and heating power according to the detection data. Alkaline washing removes oil and oxide layers from the surface of the substrate. For water washing, rinse with deionized water until neutral. After rinsing, the conductivity of the rinsing water is detected by a conductivity sensor. Once the standard is met, vacuum drying is performed (to ensure that there is no residual alkali on the substrate surface). For vacuum drying, vacuum and temperature sensors provide real-time feedback data, and the PLC controller regulates the vacuum pump power and heating temperature. The drying time is dynamically adjusted based on the substrate moisture content sensor's detection results (to avoid over-drying or insufficient drying).

[0022] More specifically, the functional coating slurry includes aqueous polyurethane resin, nano-silica, organosiloxane coupling agent, polyethylene glycol, and deionized water (specifically, the process can be as follows: first, nano-silica is added to deionized water and ultrasonically dispersed (power 300-500W, time 20-30min) to form a nano-dispersion; then, aqueous polyurethane resin is added and stirred at 500-800r / min for 30-40min; finally, organosiloxane coupling agent and polyethylene glycol are added and stirred for another 20-25min; the viscosity sensor's detection accuracy is ≤1mPa·s). Aqueous polyurethane resin, as a film-forming base material, possesses good flexibility and adhesion; nano-silica can improve coating hardness and wear resistance; organosiloxane coupling agent can bridge the substrate and coating, further enhancing the bonding force; polyethylene glycol can improve the leveling and flexibility of the coating. Ultrasonic dispersion is used to prepare the nano-dispersion, ensuring uniform dispersion of nano-silica and avoiding agglomeration that affects coating performance; microgravure coating can precisely control the coating thickness and ensure coating uniformity.

[0023] Furthermore, step S5 is followed by: Step S6: The finished products after embossing are subjected to performance testing by a fully automated testing system, including water contact angle tester to test hydrophobicity, abrasion tester to test abrasion resistance cycles, solvent resistance tester to test alcohol resistance, and adhesion tester to test coating adhesion. Unqualified products are automatically diverted to the recycling module, and qualified products are collected and stored.

[0024] Furthermore, the predetermined texture in step S5 is a hexagonal honeycomb structure. The texture structure can form an air layer on the label surface, reducing the contact area between the liquid and the surface and improving the waterproof and stain-resistant performance.

[0025] It is worth mentioning that the technical features such as self-adhesive labels involved in this patent application should be regarded as prior art. The specific structure, working principle, and possible control methods and spatial arrangement of these technical features can be adopted using conventional choices in the field, and should not be regarded as the inventive point of this patent. This patent will not be further elaborated in detail.

[0026] For those skilled in the art, modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the protection scope of this invention.

Claims

1. A surface treatment process for self-adhesive labels, characterized in that, Includes the following steps: Step S1: Perform pretreatment by selecting PET film as the substrate for self-adhesive labels and sequentially performing alkaline washing, water washing, and vacuum drying on the substrate. Step S2: Perform plasma activation. The pretreated substrate is sent into a low-temperature plasma treatment device. The flow rate of the argon-oxygen mixed gas is monitored in real time by a gas flow sensor to form active groups on the surface of the substrate. Step S3: Apply a functional coating. Prepare a functional coating slurry and apply it using a micro-gravure coating method. During the coating process, the dry film thickness is detected in real time by a laser thickness gauge, and the PLC controller adjusts parameters including the coating roller speed, coating head pressure, and substrate conveying speed to ensure uniform coating thickness. Step S4: Perform gradient curing, first pre-curing at the first temperature for the first time, then raising the temperature to the second temperature for main curing, and finally cooling down to the third temperature for the third time for post-curing; Step S5: Perform surface texture imprinting. The cured substrate is fed into a texture imprinting device, and an imprinting roller with micron-level concave and convex textures is used to form a predetermined texture on the surface of the substrate.

2. The surface treatment process for self-adhesive labels according to claim 1, characterized in that, Step S1 is implemented as follows: For alkaline washing, the concentration of sodium hydroxide solution is detected in real time by an online concentration sensor, the processing temperature is detected by a temperature sensor, and the PLC controller dynamically adjusts the solution replenishment and heating power according to the detection data. Alkaline washing removes oil and oxide layers from the surface of the substrate. For water washing, rinse with deionized water until neutral. After water washing, the conductivity of the rinsing water is detected by a conductivity sensor. Once it meets the standard, it enters vacuum drying. For vacuum drying, vacuum and temperature sensors provide real-time feedback data, and the PLC controller regulates the vacuum pump power and heating temperature. The drying time is dynamically adjusted based on the detection results of the substrate moisture content sensor.

3. The surface treatment process for self-adhesive labels according to claim 2, characterized in that, Functional coating slurries include polyurethane resin, nano-silica, organosiloxane coupling agent, polyethylene glycol, and deionized water.

4. The surface treatment process for self-adhesive labels according to claim 3, characterized in that, Step S5 is followed by: Step S6: The finished products after embossing are subjected to performance testing by a fully automated testing system, including water contact angle tester to test hydrophobicity, abrasion tester to test abrasion resistance cycles, solvent resistance tester to test alcohol resistance, and adhesion tester to test coating adhesion. Unqualified products are automatically diverted to the recycling module, and qualified products are collected and stored.

5. The surface treatment process for self-adhesive labels according to claim 4, characterized in that, The predetermined texture in step S5 is a hexagonal honeycomb structure.

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