A 3D printable liquid-like flexographic printing plate and preparation method thereof

Abstract

The present invention discloses a 3D-printable liquid-like flexographic printing plate and a preparation method thereof. The liquid-like flexographic printing plate is prepared from 60-90 wt% of a resin matrix, 1-10 wt% of liquid-like molecules, 1-5 wt% of a photoinitiator, and 0-30 wt% of an auxiliary agent. The liquid-like molecules are one of monofunctional end-capped polydimethylsiloxane, perfluoropolyether, polyisobutylene, and polyethylene glycol. The present invention utilizes DLP light curing to 3D print a liquid-like flexographic printing plate. The flexographic printing plate adopts a combination of a resin matrix (acrylate-based, polyurethane-based, epoxy-based) and liquid-like molecules to give its surface excellent static oleophilic and dynamic oleophobic properties. By rationally regulating the structure and distribution of the liquid-like molecules, the ink transfer ability of the printing plate is enhanced, the printing quality is improved, and ink residue is reduced.

Description

Technical Field

[0001] The present invention belongs to the field of flexographic printing plate making, and relates to a flexible printing plate (flexographic plate), and in particular to a flexible printing plate based on a PDMS-type liquid surface and a preparation method thereof. Background Art

[0002] Flexographic printing is a printing technology widely used for packaging, labels, and corrugated paper. Its main feature is the flexibility of the printing plate, which can adapt to different substrates. Traditional flexographic printing plates are usually made of photosensitive resin materials and are made through multiple steps such as exposure, development, cleaning, and drying. However, this traditional plate making method has many limitations:

[0003] (1) The platemaking process is complex and the production efficiency is low: The preparation of traditional flexographic plates requires multiple steps, including UV exposure, development, plate washing and post-curing. The entire process is time-consuming and labor-intensive, and the platemaking cycle is long. (2) The printing plate is difficult to clean and has a limited service life: During the printing process, the ink easily adheres to the surface of the printing plate. After long-term use, it needs to be cleaned frequently, otherwise it will affect the printing quality. Traditional resin-based flexographic plates have high surface energy and are difficult to clean, which can easily lead to printing downtime. (3) Ink transfer is limited, affecting printing quality: Due to the surface characteristics of traditional flexographic materials, the wettability and transfer efficiency of ink on the printing plate are limited, which may cause ink accumulation or unevenness, affecting printing accuracy. (4) High-precision patterns are difficult to achieve: The microstructure processing accuracy of traditional flexographic plates is limited, making it difficult to achieve high-fidelity reproduction of ultra-fine graphics and complex patterns.

[0004] In recent years, the development of materials science has prompted researchers to explore more functional printing plate materials, among which liquid-like surface technology has attracted widespread attention. Liquid-like surface is a solid material surface with liquid-like properties, which exhibits static oleophilicity and dynamic oleophobicity. This surface property gives it many advantages in printing applications: (1) Excellent ink wettability: Under static conditions, the ink can be evenly spread on the liquid-like surface, improving the coverage and consistency of the ink during the printing process. (2) High ink transfer efficiency: During the dynamic printing process, the liquid-like surface can reduce ink residue and improve the ink transfer efficiency, making the printed dots clearer and the colors richer. (3) Strong self-cleaning ability: Due to the dynamic oleophobic property, the ink is not easy to adhere to the printing plate, which reduces the contamination of the printing plate, reduces the cleaning frequency, and improves the printing production efficiency. (4) High durability: The liquid-like surface has strong chemical stability and is not easily aged due to ink erosion or mechanical friction, which increases the service life of the flexographic plate. This feature makes the liquid-like surface an ideal printing plate surface material, which can effectively improve the quality and efficiency of flexographic printing.

[0005] With the development of 3D printing technology, it has become possible to directly manufacture printing plates using digital means. For example, photocuring 3D printing can construct three-dimensional structures layer by layer with high precision. If digital light processing (DLP) technology can be applied to the direct preparation of flexographic plates, it will be expected to simplify the platemaking process, reduce costs, and improve platemaking accuracy. In addition, flexographic printing has high requirements for ink transfer efficiency and plate durability, and existing printing plate materials are difficult to strike a balance between ink affinity and easy cleaning. To this end, it is necessary to develop a new type of flexographic plate whose surface material is easy to adhere to ink when stationary, and can quickly release ink when in dynamic contact during printing, thereby improving printing transfer efficiency and facilitating cleaning. Summary of the Invention

[0006] To improve the ink transfer efficiency of flexographic printing plates, reduce plate cleaning frequency, lower production and maintenance costs, extend plate life, and enhance environmental friendliness and printability, the present invention provides a 3D-printable liquid-like flexographic printing plate and its preparation method. The present invention utilizes DLP technology to combine special materials (including resins and monofunctional end-capped linear polymer molecules) to prepare the flexographic plate, imparting static oleophilic and dynamic oleophobic properties to the surface, thereby improving ink transfer efficiency, self-cleaning ability, and printability.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] A 3D printable liquid-like flexographic printing plate is prepared from 60-90 wt% of a resin matrix, 1-10 wt% of liquid-like molecules (single functional group end-capped), 1-5 wt% of a photoinitiator, and 0-30 wt% of an auxiliary agent, wherein:

[0009] The resin matrix is one or a mixture of polyurethane acrylate, epoxy acrylate, polyester acrylate, 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, 2-phenoxyethyl acrylate, methoxy-terminated polyurethane acrylate, ethoxylated bisphenol A diacrylate, bisphenol A diglycidyl ether, ethoxylated bisphenol A diglycidyl ether, and bisphenol F diglycidyl ether;

[0010] The liquid-like molecule is one of monofunctional end-capped polydimethylsiloxane, perfluoropolyether, polyisobutylene, and polyethylene glycol, has a molecular weight of 100 to 100,000, and the monofunctional group is one of hydroxyl, amino, epoxy, vinyl, acyl chloride, carbamate, and carboxyl groups;

[0011] The photoinitiator is one of an acrylate system, a polyurethane system, and an epoxy resin system, preferably one of trimethylbenzoyl-diphenylphosphine oxide, phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, triarylsulfonium hexafluorophosphate, and iodonium salt;

[0012] The auxiliary agent is one of a plasticizer and a stabilizer or a mixture of the two.

[0013] A method for preparing the above-mentioned 3D printable liquid-like flexographic printing plate comprises the following steps:

[0014] Step 1: Prepare a resin composition for DLP photocuring: add a resin matrix, liquid-like molecules, a photoinitiator, and an additive, mix and stir, and then vacuum to remove bubbles;

[0015] Step 2: Pour the resin composition prepared in step 1 into the resin tank of the DLP 3D printer, and perform exposure and curing layer by layer according to the designed flexographic model. The layer thickness is controlled to be 10-100 microns, the exposure time is 1-20 seconds per layer, and the light intensity is 1-30mW / cm 2 ;

[0016] Step 3: After printing is completed, remove the formed flexographic substrate from the printer, clean the uncured resin remaining on the surface, and then perform global secondary curing on the printing plate under ultraviolet light, controlling the global secondary curing time to 5 to 60 minutes.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] 1. The present invention provides a flexible printing plate based on a PDMS liquid surface, which is a combination of a resin matrix and a PDMS liquid material (the specific structure is as follows Figure 1 As shown in the figure, the surface of the PDMS has excellent static oleophilic and dynamic oleophobic properties. By rationally regulating the structure and distribution of PDMS, the ink transfer ability of the printing plate is enhanced, the printing quality is improved, and ink residue is reduced. The specific performance is as follows:

[0019] (1) Liquid-like surface properties: static oleophilicity (e.g. Figure 2 As shown), dynamic oleophobic (as shown Figure 3 As shown), improve ink wettability and transfer performance;

[0020] (2) High adaptability: suitable for different types of inks (such as water-based inks, solvent-based inks, UV inks, etc.);

[0021] (2) High resolution: supports 10-20μm fine pattern printing to ensure printing quality;

[0022] (4) High wear resistance: PDMS enhances the durability of the flexographic plate, making it stable under high-load printing conditions;

[0023] (5) High environmental protection: reduce ink waste, reduce cleaning agent consumption, and meet green printing standards.

[0024] 2. The improvements and main performance indicators of the flexographic printing plate of the present invention compared with the traditional flexographic plate are shown in Table 1 and Table 2:

[0025] Table 1

[0026]

[0027] Table 2

[0028]

[0029] BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the liquid-like flexographic structure;

[0031] Figure 2 is the static contact angle of oil-based ink on the PDMS liquid surface;

[0032] Figure 3 A photo of oil-based ink sliding on a liquid-like surface;

[0033] Figure 4 This is a laser confocal microscope photo of a liquid-like flexo plate;

[0034] Figure 5 It is a liquid-like flexographic printing product. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is further described below with reference to the accompanying drawings, but is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention that does not depart from the spirit and scope of the technical solution of the present invention should be included in the scope of protection of the present invention.

[0036] The present invention provides a 3D printable liquid-like flexographic printing plate, which is prepared from 60-90 wt% of a resin matrix, 1-10 wt% of liquid-like molecules (single functional group end-capping), 1-5 wt% of a photoinitiator, and 0-30 wt% of an auxiliary agent, wherein:

[0037] The resin matrix is a mixture of one or more of polyurethane acrylate, epoxy acrylate, polyester acrylate, 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, 2-phenoxyethyl acrylate, methoxy-terminated polyurethane acrylate, ethoxylated bisphenol A diacrylate, bisphenol A diglycidyl ether, ethoxylated bisphenol A diglycidyl ether, and bisphenol F diglycidyl ether to provide the necessary mechanical strength.

[0038] The liquid-like molecules (single functional group end-capping) are one of polydimethylsiloxane, perfluoropolyether, polyisobutylene, and polyethylene glycol with single functional group end-capping (hydroxyl, amino, epoxy, vinyl, acyl chloride, carbamate, or carboxyl) and have a molecular weight of 100,000 to 100,000, so that they can form a stable liquid-like surface.

[0039] The selection of the photoinitiator is crucial to the speed and curing depth of the photocuring reaction. In the present invention, the photoinitiator is one of an acrylate system, an epoxy resin system and a polyurethane system, preferably one of TPO (Diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide, trimethylbenzoyl-diphenylphosphine oxide), Irgacure 819 (Phenylbis (2,4,6-trimethylbenzoyl) phosphine oxide, phenyl bis (2,4,6-trimethylbenzoyl) phosphine oxide), Irgacure 2959 (2-Hydroxy-2-methylpropiophenone, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone), Triarylsulfonium Hexafluorophosphate (triarylsulfonium hexafluorophosphate), and Iodonium Salt (iodonium salt).

[0040] The auxiliary agent is one of a plasticizer and a stabilizer or a mixture of the two to optimize the performance of the flexographic plate. The mass ratio of the plasticizer to the stabilizer is 1:1-10.

[0041] The present invention also provides a method for preparing the above-mentioned 3D printable liquid-like flexographic printing plate, the method comprising the following steps:

[0042] Step 1: Prepare a resin composition for DLP photocuring: add a resin matrix, liquid-like molecules (single functional group end-capping), a photoinitiator, an epoxy resin system, and an additive, mix and stir for 10 to 60 minutes, and then vacuum treat for 10 to 60 minutes to remove bubbles.

[0043] Step 2: Pour the resin composition prepared in step 1 into the resin tank of the DLP 3D printer, and perform exposure and curing layer by layer according to the designed flexographic model. The printing parameters such as layer thickness (10-100 microns), exposure time (1-20 seconds per layer) and light intensity (1-30mW / cm 2 ) is optimized according to the resin formulation.

[0044] Step 3. After printing is completed, remove the formed flexographic substrate from the printer, use ethanol, isopropyl alcohol and other solvents to ultrasonically clean the uncured resin remaining on the surface, and then perform global secondary curing (post-curing) on the printing plate under ultraviolet light for 5 to 60 minutes to fully cure the resin matrix and improve its mechanical properties and solvent resistance.

[0045] The present invention utilizes DLP light-curing 3D printing to create a flexible printing plate with liquid-like properties. This flexographic plate utilizes a combination of a resin matrix (acrylate, polyurethane, or epoxy) and liquid-like molecules to impart excellent static oleophilic and dynamic oleophobic properties to its surface. By rationally regulating the structure and distribution of the liquid-like molecules, the plate's ink transfer capability is enhanced, print quality is improved, and ink residue is reduced. The specific advantages are as follows:

[0046] 1. Improve ink transfer efficiency: Through the static oleophilic and dynamic oleophobic properties of the liquid-like surface, the wettability and transfer efficiency of the ink are improved, ink accumulation is reduced, and the printed dots are clearer and the colors are more uniform.

[0047] 2. Reduce the frequency of plate cleaning and reduce production and maintenance costs: Since the liquid-like surface has dynamic oleophobic properties, the ink is not easy to adhere to the plate surface during the printing process, thereby reducing ink residue, improving self-cleaning ability, and reducing the frequency of shutdown for cleaning.

[0048] 3. Extend the service life of the printing plate: The liquid-like surface has excellent chemical resistance and mechanical friction resistance, which can reduce the erosion of ink on the printing plate, so that the printing plate can maintain good printing quality during long-term use and extend its service life.

[0049] 4. Improve environmental protection: Reduce the use of chemical solvents required for cleaning the printing plate in the traditional printing process, reduce volatile organic compound (VOC) emissions, and better meet the requirements of green and environmentally friendly printing processes.

[0050] 5. Improve printing adaptability: Liquid-like surface flexographic printing plates are suitable for different types of inks (such as water-based inks, solvent-based inks, UV inks, etc.), and can maintain stable printing performance on different substrates, thereby improving printing consistency and adaptability.

[0051] 6. The application of DLP technology in the direct preparation of flexographic plates is expected to simplify the platemaking process, reduce costs, and improve platemaking accuracy.

[0052] Example 1:

[0053] This embodiment provides a liquid-like flexographic printing plate suitable for solvent-based inks and UV inks. The specific preparation method is as follows:

[0054] (1) Prepare a resin composition for DLP photocuring. Add polyurethane acrylate matrix (70 wt%), epoxy acrylate (20 wt%), monohydroxyl-terminated polydimethylsiloxane molecules (1 wt%, molecular weight 6000), photoinitiator TPO (1 wt%), plasticizer (4 wt%), and stabilizer (4 wt%). Mix and stir for 30 minutes, then remove bubbles in a vacuum for 30 minutes.

[0055] (2) Pour the above resin into the resin tank of the DLP 3D printer and perform exposure and curing layer by layer according to the designed flexographic model. Printing parameters: layer thickness: 50 microns, exposure time: 10 seconds per layer, light intensity: 10mW / cm 2 .

[0056] (3) After printing is completed, the formed flexographic substrate is removed from the printer, and the uncured resin remaining on the surface is cleaned with ethanol ultrasonically, and then the printing plate is globally cured (post-cured) under ultraviolet light for 30 minutes. Figure 4 As shown, the printed product is as Figure 5 shown.

[0057] Example 2:

[0058] This embodiment provides a liquid-like flexographic printing plate suitable for solvent-based inks and UV inks. The specific preparation method is as follows:

[0059] (1) Prepare a resin composition for DLP photocuring. Add bisphenol A diglycidyl ether (70 wt%), epoxy acrylate (10 wt%), monoepoxy-terminated perfluoropolyether molecules (2 wt%, molecular weight 10,000), photoinitiator iodonium salt (2 wt%), and stabilizer (16 wt%). Mix and stir for 40 minutes, then remove bubbles in a vacuum for 20 minutes.

[0060] (2) Pour the above resin into the resin tank of the DLP 3D printer and perform exposure and curing layer by layer according to the designed flexographic model. Printing parameters: layer thickness: 30 microns, exposure time: 5 seconds per layer, light intensity: 15mW / cm 2 .

[0061] (3) After printing is completed, the formed flexographic substrate is removed from the printer, and the uncured resin remaining on the surface is cleaned ultrasonically with ethanol, and then the printing plate is globally secondary cured (post-cured) under ultraviolet light for 40 min.

[0062] Example 3:

[0063] This embodiment provides a liquid-like flexographic printing plate suitable for water-based ink, and the specific preparation method is as follows:

[0064] (1) Prepare a resin composition for DLP photocuring. Add ethoxylated bisphenol A diacrylate (70 wt%), polyurethane acrylate (20 wt%), polyethylene glycol (5 wt%, molecular weight 5000), photoinitiator Irgacure 819 (1 wt%), plasticizer (2%), and stabilizer (2%). Mix and stir for 30 minutes, then remove bubbles in a vacuum for 20 minutes.

[0065] (2) Pour the above resin into the resin tank of the DLP 3D printer and perform exposure and curing layer by layer according to the designed flexographic model. Printing parameters: layer thickness: 20 microns, exposure time: 10 seconds per layer, light intensity: 20mW / cm 2 .

[0066] (3) After printing is completed, the formed flexographic substrate is removed from the printer, and the uncured resin remaining on the surface is ultrasonically cleaned with isopropyl alcohol, and then the printing plate is globally secondary cured (post-cured) under ultraviolet light for 30 minutes.

[0067] Example 4:

[0068] This embodiment provides a liquid-like flexographic printing plate suitable for solvent-based inks and UV inks. The specific preparation method is as follows:

[0069] (1) Prepare a resin composition for DLP photocuring. Add a polyurethane acrylate matrix (60 wt%), a monohydroxyl-terminated polydimethylsiloxane molecule (10 wt%, molecular weight 10,000), a photoinitiator TPO (1 wt%), a plasticizer (26 wt%), and a stabilizer (3 wt%). Mix and stir for 30 minutes, then vacuum and remove bubbles for 30 minutes.

[0070] (2) Pour the above resin into the resin tank of the DLP 3D printer and perform exposure and curing layer by layer according to the designed flexographic model. Printing parameters: layer thickness: 50 microns, exposure time: 10 seconds per layer, light intensity: 10mW / cm 2 .

[0071] (3) After printing is completed, the formed flexographic substrate is removed from the printer, and the uncured resin remaining on the surface is cleaned with ethanol ultrasonically, and then the printing plate is globally secondary cured (post-cured) under ultraviolet light for 30 minutes.

[0072] Example 5:

[0073] This embodiment provides a liquid-like flexographic printing plate suitable for solvent-based inks and UV inks. The specific preparation method is as follows:

[0074] (1) Prepare a resin composition for DLP photocuring. Add polyurethane acrylate matrix (70 wt%), epoxy acrylate (20 wt%), monohydroxyl-terminated polydimethylsiloxane molecules (8 wt%, molecular weight 6000), and photoinitiator TPO (2 wt%). Mix and stir for 30 minutes, then remove bubbles in a vacuum for 30 minutes.

[0075] (2) Pour the above resin into the resin tank of the DLP 3D printer and perform exposure and curing layer by layer according to the designed flexographic model. Printing parameters: layer thickness: 50 microns, exposure time: 15 seconds per layer, light intensity: 10mW / cm 2 .

[0076] (3) After printing is completed, the formed flexographic substrate is removed from the printer, and the uncured resin remaining on the surface is cleaned with ethanol ultrasonically, and then the printing plate is globally secondary cured (post-cured) under ultraviolet light for 30 minutes.

Claims

1. A 3D printable liquid-like flexographic printing plate, characterized in that The liquid-like flexographic printing plate is prepared from 60-90 wt% of a resin matrix, 1-10 wt% of liquid-like molecules, 1-5 wt% of a photoinitiator, and 0-30 wt% of an auxiliary agent. The liquid-like molecules are one of polyethylene glycol, monofunctional end-capped polydimethylsiloxane, and monofunctional end-capped perfluoropolyether.

2. The 3D printable liquid-like flexographic printing plate according to claim 1, characterized in that The resin matrix is one or a mixture of polyurethane acrylate, epoxy acrylate, polyester acrylate, 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, 2-phenoxyethyl acrylate, methoxy-terminated polyurethane acrylate, ethoxylated bisphenol A diacrylate, bisphenol A diglycidyl ether, ethoxylated bisphenol A diglycidyl ether, and bisphenol F diglycidyl ether.

3. The 3D printable liquid-like flexographic printing plate according to claim 1, characterized in that The molecular weight of the liquid-like molecules is 100 to 100,000.

4. The 3D printable liquid-like flexographic printing plate according to claim 1, characterized in that The monofunctional group is one of hydroxyl, amino, epoxy, vinyl, acyl chloride, carbamate, and carboxyl.

5. The 3D printable liquid-like flexographic printing plate according to claim 1, characterized in that The photoinitiator is one of an acrylate system, a polyurethane system, and an epoxy resin system.

6. The 3D printable liquid-like flexographic printing plate according to claim 1, characterized in that The photoinitiator is one of trimethylbenzoyl-diphenylphosphine oxide, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, triarylsulfonium hexafluorophosphate, and iodonium salt.

7. The 3D printable liquid-like flexographic printing plate according to claim 1, characterized in that The auxiliary agent is one of a plasticizer and a stabilizer or a mixture of the two.

8. A method for preparing a 3D printable liquid-like flexographic printing plate according to any one of claims 1 to 7, characterized in that The method comprises the following steps: Step 1: Prepare a resin composition for DLP photocuring: add a resin matrix, liquid-like molecules, a photoinitiator, and an additive, mix and stir, and then vacuum to remove bubbles; Step 2: Pour the resin composition prepared in step 1 into the resin tank of the DLP 3D printer, and perform exposure and curing layer by layer according to the designed flexographic model; Step 3: After printing is completed, remove the formed flexographic substrate from the printer, clean the uncured resin remaining on the surface, and then perform global secondary curing on the printing plate under ultraviolet light.

9. The method for preparing a 3D printable liquid-like flexographic printing plate according to claim 8, characterized in that In step 2, the layer thickness is controlled to be 10-100 microns, the exposure time is 1-20 seconds per layer, and the light intensity is 1-30 mW / cm 2 .

10. The method for preparing a 3D printable liquid-like flexographic printing plate according to claim 8, characterized in that In step three, the global secondary curing time is controlled to be 5~60 min.

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