Preparation process of double-sided highlight composite coated playing card paper

Abstract

The invention discloses a preparation process of double-sided highlight composite coated playing card paper. The preparation process comprises the following steps: activating a base material by plasmas, coating the double sides of the playing card paper with a high-refraction coating containing core-shell nano TiO2, carrying out gradient pre-curing, compounding a polyester film, carrying out mirror roll calendering, dynamically humidifying and carrying out integrated waste gas treatment. Through the core-shell material design and the synergistic effect of gradient curing and micro-foaming technologies, the double-sided high glossiness of 95% or above is achieved; an antibacterial agent and a perfluorinated coating are added, so that long-acting antibacterial and antifouling performance is achieved; and environment-friendly production is ensured by a solvent recovery and catalytic oxidation system. The product has the characteristics of high gloss, durability and antibacterial property, and is suitable for manufacturing high-end playing cards.

Description

Technical Field

[0001] The present invention relates to the technical field of special paper processing, and particularly to a preparation process for double-sided high-gloss composite coated playing card paper. Background Art

[0002] Traditional playing card paper mostly adopts single-sided coating or ordinary lamination process, which has problems such as insufficient gloss, easy wear, and poor stain resistance. In the prior art, high-gloss coated paper often improves gloss through a single curing process or ordinary calendering treatment, but it is easy to cause poor coating adhesion, low folding resistance, and lack of antibacterial function. In addition, in the composite process, solvent volatilization and waste gas treatment are not perfect, and the environmental protection is insufficient. Therefore, there is an urgent need for a preparation process for playing card paper that integrates high gloss, antibacterial property, and environmental protection. Summary of the Invention

[0003] In view of the above deficiencies, the present invention proposes a preparation process for double-sided high-gloss composite coated playing card paper, which is suitable for the production of high-end playing card paper that requires high gloss, antibacterial property, and durability.

[0004] To achieve the above object, the present invention provides a preparation process for double-sided high-gloss composite coated playing card paper, including the following steps: S1. Substrate pretreatment: The original paper substrate is subjected to double-sided activation treatment by dielectric barrier discharge plasma, with a pulse frequency of 5 - 20 kHz and a duty cycle of 30 - 50%. After treatment, the oxygen element content on the substrate surface is increased by 3 - 5 times, enhancing the coating adhesion; S2. Double-sided synchronous coating: Use an intaglio coating machine to coat both sides of the activated substrate with a high refractive index coating; S3. Gradient pre-curing: A pre-cured coating layer is formed by directional curing through three temperature zones, and the directional curing is carried out successively through three temperature zones: the first temperature zone of 80 ± 5 °C, the second temperature zone of 110 ± 5 °C, and the third temperature zone of 130 ± 5 °C, with a residence time of 30 - 60 s in each zone; S4. Composite lamination: The pre-cured coating layer is laminated with a transparent polyester film; S5. On-line calendering treatment: After lamination, further hot calendering is carried out using a mirror stainless steel roller; S6. Dynamic humidity conditioning balance: After hot calendering, a 24 - 48 h balance treatment is carried out through a humidity gradient control box, and the humidity of the humidity gradient control box is adjusted in a stepwise manner according to 30% - 50% - 65%.

[0005] Preferably, the high refractive index coating in step S2 includes: acrylic modified polyurethane resin, nano-titanium dioxide, leveling agent, dispersant, and solvent; The nano-titanium dioxide has a core-shell structure, the core is rutile TiO2 with a refractive index of 2.7, the shell is a SiO2 coating layer with a thickness of 2 - 5 nm, and the surface of the shell layer is grafted with a fluorinated acrylate polymer with a grafting rate of ≥ 85%.

[0006] Preferably, 0.5-1.2% by mass of nano-zinc oxide-silver ion composite antibacterial agent is added to the coating. Its particle size distribution D50 = 80-120 nm, and its surface charge is modified by carboxymethyl cellulose, with its Zeta potential ranging from -35 mV to -45 mV.

[0007] Preferably, during the gradient pre-curing process in step S3, UV with a wavelength of 365 nm is introduced for auxiliary curing in the second temperature zone, with an irradiation intensity of 80-120 mW / cm² and an irradiation time of 3-5 s.

[0008] Preferably, the composite lamination process in step S4 adopts a three-stage temperature control: The first stage: maintain at 160 °C / 0.8 MPa for 10 s; The second stage: maintain at 175 °C / 1.0 MPa for 15 s; The third stage: maintain at 180 °C / 0.5 MPa for 5 s; Among them, the hot melt adhesive layer undergoes micro-foaming in the third stage, with a foaming rate of 5-8%, forming a light-scattering interface layer.

[0009] Preferably, the surface of the mirror stainless steel roller in step S5 is provided with a micro-nano composite structure, including: The macro mirror surface area with a roughness Ra ≤ 0.01 μm accounts for 70-80% of the roller surface area, The microscopic laser-etched diffraction grating area with a period of 500-800 nm and a depth of 100-150 nm accounts for 20-30%.

[0010] Preferably, in step S1, the plasma treatment adopts a pulse modulation technique, with a pulse frequency of 5-20 kHz and a duty cycle of 30-50%. The oxygen element content on the surface of the treated substrate is increased by 3-5 times.

[0011] Preferably, the gravure coating unit in step S2 is equipped with an on-line film thickness detection system, including: A ray thickness gauge with a measurement accuracy of ±0.1 g / m²β; An infrared spectrometer for real-time monitoring of the curing degree of the coating; A feedback control system for dynamically adjusting the doctor blade pressure by ±5% based on the detection data.

[0012] Preferably, in step S6, a surface functionalization treatment is added, including: Spraying an anti-fouling coating containing 0.5-1.2 μm of perfluoropolyether; Electron beam curing with an energy of 50-80 kGy to form a cross-linked network.

[0013] Preferably, in the preparation process, the waste gas treatment system is integrated into the coating production line, including: A solvent recovery unit with a condensation temperature of -15°C to -25°C and a recovery rate of ≥92%; A plasma catalytic oxidation unit with a catalyst of Mn-Ce / TiO2 honeycomb ceramics; An activated carbon adsorption + UV photolysis deep purification unit.

[0014] Advantages of the present invention: 1. Double-sided high gloss: The core-shell structure nano-TiO2 and the gradient curing process synergistically improve the refractive index and flatness of the coating, and the glossiness measured at a 60° angle is above 95%.

[0015] 2. Antibacterial and antifouling: The nano-zinc oxide-silver ion antibacterial agent and the perfluoropolyether coating endow long-term antibacterial and bacteriostatic rates of ≥99% and anti-fingerprint performance.

[0016] 3. Environmentally friendly and efficient: The solvent recovery rate is ≥92%, and the waste gas purification efficiency is >98%, meeting the requirements of green production.

[0017] 4. Durability: The micro-foamed interface layer and the humidity adjustment treatment significantly improve the folding resistance of ≥2000 times and the dimensional stability deformation of <0.5%. Description of the drawings

[0018] Figure 1 It is a schematic flow diagram of the present invention. Detailed implementation manners

[0019] In order to make the objectives and advantages of the present invention clearer, the present invention will be further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0020] The preferred implementation manners of the present invention will be described below with reference to the drawings. Those skilled in the art should understand that these implementation manners are only used to explain the technical principles of the present invention and do not limit the protection scope of the present invention.

[0021] It should be noted that in the description of the present invention, the terms indicating the direction or positional relationship such as "upper", "lower", "left", "right", "inner", "outer", etc. are based on the direction or positional relationship shown in the drawings. This is only for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.

[0022] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and defined, the terms "installation", "connection", and "linkage" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the communication inside two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0023] Example 1, as Figure 1 shown, a preparation process of a double-sided high-gloss composite coated playing card paper, and its preparation steps are as follows: Substrate pretreatment: Dielectric barrier discharge plasma treatment, pulse frequency 15 kHz, duty cycle 40%, and the oxygen element content on the substrate surface after treatment is increased from 5% to 20%.

[0024] Double-sided coating: Synchronously coat a high refractive index coating with a gravure coating unit, and the formula is: 55% acrylic modified polyurethane resin; Core-shell nano-TiO2 with a shell thickness of 3 nm and a grafting rate of 88%: 30%; Nano zinc oxide-silver ion composite antibacterial agent with D50 = 100 nm and Zeta potential -40 mV: 1%; Leveling agent: 0.5%, solvent: 13.5%, and the coating amount for both sides is 7 g / m².

[0025] Gradient pre-curing: Three-stage temperature zones 85°C / 50 s → 115°C / 50 s → 135°C / 50 s, and in the second temperature zone, UV curing is performed by introducing light with a wavelength of 365 nm and an intensity of 100 mW / cm² for 4 s.

[0026] Composite lamination: When laminating with a polyester film, the foaming rate of the hot melt adhesive in the third stage is 7% to form a scattering layer.

[0027] Calendering: Ra = 0.008 μm, and the proportion of the diffraction grating area is 25%. Hot calendering is performed with a mirror stainless steel roll at a temperature of 120°C and a pressure of 8 MPa.

[0028] Humidity conditioning treatment: Balance for 36 h in a humidity gradient control box with 30% - 50% - 65% humidity.

[0029] Functionalization: Spray a perfluoropolyether anti-fouling coating with a thickness of 1.0 μm and cure it with an electron beam of 60 kGy.

[0030] The test performance of Example 1 is as follows: Glossiness (60°): 97%, Antibacterial rate (Escherichia coli): 99.5%, Folding resistance: 2200 times, Solvent recovery rate: 93%.

[0031] Example 2, which is a low-cost and environmentally friendly process, is basically the same as Example 1, except that: Substrate pretreatment: Plasma treatment with a pulse frequency of 10 kHz and a duty cycle of 35%, and the oxygen content is increased to 18%.

[0032] Double-sided coating: The antibacterial agent is omitted from the coating, and the formulation is 60% acrylic polyurethane resin, 25% core-shell nano-TiO2, and 15% solvent.

[0033] Gradient pre-curing: Three temperature zones of 80 °C / 60 s → 110 °C / 60 s → 130 °C / 60 s, without UV assistance.

[0034] Composite lamination: The foaming rate of the hot melt adhesive is 5%, and the temperature in the third stage is 180 °C.

[0035] Calendering: Calendering with a common mirror roller with Ra = 0.01 μm.

[0036] Humidity conditioning treatment: Humidity step balance for 24 h.

[0037] The test performance of Example 2 is as follows: Glossiness (60°): 92% Antibacterial rate: Not added, no significant antibacterial property Flex resistance: 1800 times Solvent recovery rate: 95% (due to the absence of antibacterial agent, the solvent purity is higher).

[0038] Example 3, which is a high-speed production process, is basically the same as Example 1, and the difference in the preparation steps is: Substrate pretreatment: High-frequency plasma with 20 kHz and a duty cycle of 50%, and the oxygen content is increased to 22%.

[0039] Double-sided coating: Add 0.8% antibacterial agent to the coating, and the coating speed is increased to 120 m / min.

[0040] Gradient pre-curing: The time in the three temperature zones is shortened to 30 s / zone, and the UV intensity is 120 mW / cm².

[0041] Composite lamination: The foaming rate is 8%, and the time in the third stage is shortened to 3 s.

[0042] Calendering: Calendering with a 30% micro-nano composite structure roller in the grating area.

[0043] Humidity conditioning treatment: Dynamic humidity conditioning is compressed to 24 h.

[0044] Its test performance is as follows: Glossiness (60°): 94%, Antibacterial rate: 98.8%, Folding resistance: 2000 times, Production speed: increased by 40%.

[0045] The performance comparison between Examples 1 - 3 and the prior art, i.e., ordinary single - sided poker paper, is as follows in the table:

[0046] As can be seen from the above table, the high - gloss performance of the present invention: Through the core - shell TiO2 and gradient curing technology, the double - sided glossiness is increased by more than 15% (vs 82% for single - sided).

[0047] Function expansion: In Example 1, an antibacterial agent and an antifouling coating are added, achieving a bacteriostatic rate of 99.5%, filling the gap in the prior art.

[0048] Environmental protection: The solvent recovery rate is increased from 60% in the traditional process to ≥90%, and the waste gas purification unit reduces VOC emissions by 90%.

[0049] Process adaptability: Example 2 shows a low - cost solution (omitting the antibacterial agent), and Example 3 verifies the feasibility of high - speed production, reflecting the flexibility of the process.

[0050] Durability: The micro - foamed interface layer and humidity - conditioning treatment increase the folding resistance by more than 2 times, solving the problem of easy cracking of traditional poker paper.

[0051] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the protection scope of the present invention.

Claims

1. A preparation process for a double-sided high-gloss composite coated playing card paper, characterized in that, It includes the following steps: S1. Substrate pretreatment: The base paper substrate is subjected to double-sided activation treatment using dielectric barrier discharge plasma. S2. Double-sided synchronous coating: The activated substrate is coated with a high refractive index coating on both sides using a gravure coating unit. S3. Gradient pre-curing: A pre-cured coating layer is formed by directional curing through three temperature zones. It is sequentially directionally cured through three temperature zones: the first temperature zone at 80 ± 5 °C, the second temperature zone at 110 ± 5 °C, and the third temperature zone at 130 ± 5 °C, with a residence time of 30 - 60 s in each zone. S4. Composite lamination: The pre-cured coating layer is laminated with a transparent polyester film. S5. Online calendering treatment: After lamination, it is further calendered using a mirror stainless steel roller. S6. Dynamic humidity conditioning balance: After calendering, it is subjected to a 24 - 48 h balance treatment through a humidity gradient control box, and the humidity in the humidity gradient control box is adjusted stepwise according to 30% - 50% - 65%.

2. The preparation process of a double-sided high-gloss composite coated playing card paper according to claim 1, characterized in that, The high refractive index coating described in step S2 includes: acrylic modified polyurethane resin, nano-titanium dioxide, leveling agent, dispersant, and solvent. The nano-titanium dioxide has a core-shell structure, with the core being rutile TiO2 with a refractive index of 2.7, and the shell being a SiO2 coating layer with a thickness of 2 - 5 nm, and the surface of the shell layer is grafted with a fluorinated acrylate polymer with a grafting rate ≥ 85%.

3. The preparation process of a double-sided high-gloss composite coated playing card paper according to claim 2, characterized in that, A nano-zinc oxide-silver ion composite antibacterial agent with a mass fraction of 0.5 - 1.2% is added to the coating. Its particle size distribution D50 = 80 - 120 nm, and its surface charge is modified by carboxymethyl cellulose, with a Zeta potential of -35 mV to -45 mV.

4. The preparation process of a double-sided high-gloss composite coated playing card paper according to claim 1, characterized in that, During the gradient pre-curing process of step S3, UV-assisted curing with a wavelength of 365 nm is introduced in the second temperature zone, with an irradiation intensity of 80 - 120 mW / cm² and an irradiation time of 3 - 5 s.

5. The preparation process of a double-sided high-gloss composite coated playing card paper according to claim 1, characterized in that, The composite lamination process described in step S4 adopts three-stage temperature control: The first stage: 160 °C / 0.8 MPa for 10 s; The second stage: 175 °C / 1.0 MPa for 15 s; The third stage: 180 °C / 0.5 MPa for 5 s; Among them, the hot melt adhesive layer undergoes micro-foaming in the third stage, with a foaming rate of 5 - 8%, forming a light-scattering interface layer.

6. The preparation process of a double-sided high-gloss composite coated playing card paper according to claim 1, characterized in that, The surface of the mirror stainless steel roller in step S5 is provided with a micro-nano composite structure, including: The macro mirror surface area with a roughness Ra ≤ 0.01 μm accounts for 70 - 80% of the roller surface area. The microscopic laser-etched diffraction grating area with a period of 500 - 800 nm and a depth of 100 - 150 nm accounts for 20 - 30%.

7. The preparation process of a double-sided high-gloss composite coated playing card paper according to claim 1, characterized in that, The plasma treatment described in step S1 adopts pulse modulation technology, with a pulse frequency of 5 - 20 kHz and a duty cycle of 30 - 50%. The oxygen element content on the surface of the treated substrate is increased by 3 - 5 times.

8. The preparation process of a double-sided high-gloss composite coated playing card paper according to claim 1, characterized in that, The gravure coating unit described in step S2 is equipped with an online film thickness detection system, including: A beta-ray thickness gauge with a measurement accuracy of ±0.1 g / m². An infrared spectrometer for real-time monitoring of the curing degree of the coating. A feedback control system for dynamically adjusting the doctor blade pressure by ±5% based on the detection data.

9. The preparation process of a double-sided high-gloss composite coated playing card paper according to claim 1, characterized in that, In step S6, a surface functionalization treatment is added, including: Spraying an anti-fouling coating containing perfluoropolyether with a thickness of 0.5 - 1.2 μm. Electron beam curing with an energy of 50 - 80 kGy to form a crosslinked network.

10. The preparation process of a double-sided high-gloss composite coated playing card paper according to claim 1, characterized in that, In the described preparation process, the waste gas treatment system is integrated into the coating production line and includes: A solvent recovery unit with a condensation temperature of -15°C to -25°C and a recovery rate of ≥92%; A plasma catalytic oxidation unit with a catalyst of Mn-Ce / TiO2 honeycomb ceramics; An activated carbon adsorption + UV photocatalysis deep purification unit.

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