Microstructure anti-sticking type on-machine developing negative image CTP plate material and preparation method thereof

Abstract

The invention provides a microstructure anti-sticking type on-machine developing negative image CTP plate material and a preparation method thereof, and belongs to the technical field of lithographic printing plate materials. The plate material comprises an aluminum-based substrate, a photosensitive layer and a surface anti-sticking layer, wherein the surface anti-sticking layer is formed by curing rough surface treatment liquid containing composite silicon dioxide particles and temperature-sensitive polymer microspheres, and the surface roughness Ra of the surface anti-sticking layer is 0.8-2.5 microns; the rough surface treating fluid comprises water, composite silicon dioxide particles, temperature-sensitive microspheres, a fluorine-containing siloxane coupling agent, epoxy modified silica sol, an ionic liquid antistatic agent and a PVP binder. According to the invention, a micron-sized composite rough surface structure is formed through ultrasonic atomization spraying and a step drying process, so that the stripping force of the plate material and the lining paper in a high-temperature and high-humidity environment is reduced to be less than or equal to 0.8 N / m, and the plate material and the lining paper have relatively high printing endurance rate, the development defect rate is 0, and the storage stability is good.

Description

Technical Field

[0001] The invention belongs to the technical field of lithographic printing plates, and specifically discloses a microstructured anti-sticking on-machine developing negative CTP plate and a preparation method thereof. Background Art

[0002] On-press negative CTP plates, which require no chemical development, have become a mainstream technology in the printing industry. However, after production, these plates are typically stacked and stored with release paper to prevent surface scratches or contamination. Traditional, unprocessed CTP plates, due to their smooth photosensitive coating, form a vacuum adsorption with the backing paper when stacked. This can lead to irreversible adhesion during storage and transportation, especially in high-temperature and high-humidity conditions (temperature ≥35°C, humidity ≥70% RH). Separation requires an external force greater than 5N / m, resulting in tearing of the coating or residual backing paper fibers.

[0003] To this end, silicone anti-sticking agents are generally added, which migrate to the photosensitive layer (migration rate > 3wt%), reducing the activity of the photosensitive components and causing dot reproducibility deviations of ±15%. While surface embossing improves roughness, it destroys coating continuity, reducing print run time to less than 50,000 impressions. Physical sandblasting roughening solutions result in localized undissolved areas during development due to uneven particle embedding depth. Conventional anti-sticking structures lose dimensional stability when exposed to temperature and humidity fluctuations, resulting in the collapse of the micro-raised structure during storage, and the anti-sticking effectiveness period is less than 3 months. Summary of the Invention

[0004] The present invention prepares a microstructured anti-sticking on-press negative CTP plate. While maintaining the integrity of the development channel of the photosensitive layer, the peeling force between the plate and the backing paper is reduced to ≤0.8N / m. The thermal expansion effect of temperature-sensitive microspheres is used to compensate for environmental stress. The porosity of the surface micro-protrusions after step drying is greater than 30%, ensuring swelling space for hydrophilic groups. This solves the problems of adhesion, development defects and poor environmental adaptability caused by the smooth surface in the prior art.

[0005] In order to achieve the above purpose, the present invention solves the technical problem by adopting the following technical solutions:

[0006] A microstructured anti-sticking on-press negative CTP plate comprises an aluminum substrate, a photosensitive layer, and a surface anti-sticking layer; the surface anti-sticking layer is formed by solidifying a matte treatment liquid containing inorganic particles, and has a surface roughness Ra of 0.8-2.5 μm;

[0007] The rough surface treatment liquid includes, by mass, 75-90 parts of water, 4-12 parts of composite silicon dioxide particles, 0.3-0.8 parts of fluorine-containing silicone coupling agent, 1.0-2.5 parts of thermosensitive polymer microspheres, 1.5-2.5 parts of epoxy-modified silica sol, 0.1-0.3 parts of ionic liquid antistatic agent, and 0.5-4.0 parts of polyvinyl pyrrolidone (PVP) adhesive.

[0008] Furthermore, in the above-mentioned plate material, the composite silica particles include spherical particles with a particle size of 1-5 μm and porous structure particles with a particle size of 10-50 μm, and the mass ratio of the spherical particles and the porous structure particles is 1:(0.5-2).

[0009] Furthermore, in the above-mentioned printing plate, the thermosensitive polymer microspheres have a glass transition temperature of 40-60°C and a volume expansion rate of 15% or greater at 50°C. Preferably, the thermosensitive polymer microspheres are acrylate copolymer microspheres. Specifically, the microspheres are of the Ganzpearl GP-200 series or the Sekisui SI-BG series.

[0010] Furthermore, in the above-mentioned plate, the ionic liquid antistatic agent is 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIM-BF4).

[0011] Furthermore, the rough surface treatment liquid of the above-mentioned plate is prepared by the following steps:

[0012] (1) Add 75-90 parts by mass of deionized water as a dispersion medium into a light-proof container;

[0013] (2) adding 0.5-4.0 parts of polyvinyl pyrrolidone (PVP) binder and stirring and dissolving at 40-50°C and 500-800 rpm for 20-40 minutes;

[0014] (3) Add 4-12 parts of composite silica particles, first disperse at a high speed of 2000-3000 rpm for 10-20 minutes, and then ultrasonicate at a power of 300-500 W and a frequency of 25 kHz for 5-15 minutes;

[0015] (4) adding 1.5-2.5 parts of epoxy modified silica sol, 0.3-0.8 parts of fluorinated siloxane coupling agent, and 0.1-0.3 parts of ionic liquid antistatic agent in sequence, maintaining a constant temperature of 40-50°C and stirring for 30-60 minutes;

[0016] (5) Finally, add 1.0-2.5 parts of thermosensitive polymer microspheres and stir at 200-400 rpm for 15-30 minutes at 25-35°C to prevent the microspheres from breaking;

[0017] (6) Filter to remove aggregates ≥100 μm to obtain a uniform suspension.

[0018] Furthermore, the method for preparing the plate comprises the following steps:

[0019] (a) coating a photosensitive layer on an aluminum substrate and drying it;

[0020] (b) spraying the matte surface treatment liquid using a reverse gravure coating process, with a coating speed of 10-30 m / min and a wet film thickness of 3-10 μm;

[0021] (c) Step drying: preheat at 60-80℃ for 3-8 seconds, then cure at 100-120℃ for 5-15 seconds.

[0022] Furthermore, in the above-mentioned method for preparing the plate, ultrasonic atomization spraying is used in the step (b), the atomization pressure is 0.2-0.5 MPa, and the droplet particle size DV50 is 20-60 μm.

[0023] The present invention also discloses the printing application of the above-mentioned plate material in a high-temperature and high-humidity environment, wherein the high-temperature and high-humidity environment has a temperature of ≥35° C. and a humidity of ≥70% RH.

[0024] Compared with the prior art, the present invention has the following outstanding beneficial effects:

[0025] The present invention discloses a microstructured anti-sticking on-press negative CTP plate and a preparation method thereof. By constructing a gradient micro-convex structure (Ra = 0.8-2.5 μm) using composite silica particles (spherical + porous), combined with the dynamic expansion effect (volume expansion ≥ 15% at 50°C) of temperature-sensitive polymer microspheres (Tg = 40-60°C), the plate-to-backing paper peeling force is reduced to ≤ 0.8 N / m while maintaining the integrity of the development channel (defect rate 0%).

[0026] Compared with traditional technologies: ① Breakthrough the problem of decreased photosensitivity caused by migration of silicone anti-adhesive (migration rate 0% vs > 3wt%); ② Reduce dust adsorption energy to 0.8mJ / m through ionic liquid antistatic agent (EMIM-BF4) 2 , the white spot defect rate dropped from 12.7% to 0.3%; ③ The step-drying process achieved a microsphere integrity rate of >93%, increasing the print run rate to ≥200,000 impressions (a 300% improvement over conventional embossing). This technology achieves environmentally adaptive anti-sticking (linear expansion coefficient ≤110ppm / °C) and a storage period of >6 months, providing a low-cost solution for printing in high-temperature and high-humidity areas. DETAILED DESCRIPTION

[0027] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] In the present invention, when referring to numerical ranges, unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Furthermore, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges subsumed therein.

[0029] In the present invention, there is no particular limitation on the specific dispersion and stirring treatment methods.

[0030] In the present invention, the test methods used are conventional methods unless otherwise specified; the materials, reagents, etc. used are reagents and materials that can be obtained from commercial channels unless otherwise specified.

[0031] The raw materials and equipment parameters used in the examples of the present invention are shown in Tables 1 and 2 below. (Including but not limited to the settings in the table)

[0032] Table 1 Raw material parameters

[0033]

[0034] Table 2 Equipment parameters

[0035]

[0036] The photosensitive layer involved in this embodiment can be prepared by existing technology, and can also be prepared preferably using the following formula and method:

[0037] 1. Synthesis of photosensitive lower layer (carboxyl modified acrylic resin):

[0038] Raw material ratio (mass parts): methyl methacrylate (MMA) 40 parts, butyl acrylate (BA) 25 parts, methacrylic acid (MAA, carboxyl-containing monomer) 20 parts, hydroxyethyl acrylate (HEA) 15 parts, azobisisobutyronitrile (AIBN) 1.2 parts, butanone (solvent) 100 parts

[0039] Preparation steps:

[0040] (1) Add butanone to a four-necked flask and heat to 80°C under nitrogen protection;

[0041] (2) The mixed monomers (MMA+BA+MAA+HEA) and AIBN were added in 4 batches, with an interval of 30 minutes between each batch;

[0042] (3) Keep the reaction warm for 5 hours, and adjust the solid content to 35% after cooling to obtain a transparent viscous resin liquid;

[0043] (4) Molecular weight control: GPC determined the weight average molecular weight (Mw) to be 80,000 ± 5000, with a dispersion of ≤1.8.

[0044] 2. Synthesis of photosensitive upper layer (phosphate-based polyurethane resin):

[0045] Raw material ratio:

[0046] 60 parts of polycaprolactone diol (PCL2000, Mn=2000), 25 parts of isophorone diisocyanate (IPDI), 10 parts of 2,2-dimethylolpropionic acid (DMPA), 5 parts of phosphate monomer (Sipomer PAM-200), 0.05 parts of dibutyltin dilaurate (catalyst), 80 parts of N-methylpyrrolidone (NMP)

[0047] Preparation steps:

[0048] (1) PCL2000, IPDI, and catalyst were added to the reactor and reacted at 85°C for 2 hours (NCO value reached 90% of the theoretical value);

[0049] (2) Add DMPA and Sipomer PAM-200 and continue the reaction at 70°C until the NCO value is less than 0.1%;

[0050] (3) Cooling to 40°C, adding triethylamine to neutralize the carboxyl groups (neutralization degree 100%), and emulsifying with water to obtain an emulsion with a solid content of 25%;

[0051] Parameters: acid value 45 mg KOH / g, phosphate content 1.2 mmol / g.

[0052] Example 1

[0053] A microstructured anti-sticking on-press negative CTP plate comprises an aluminum-based substrate, a photosensitive layer and a surface anti-sticking layer; the surface anti-sticking layer is formed by solidifying a matte surface treatment liquid containing inorganic particles.

[0054] 1. Raw material composition of rough surface treatment liquid (mass fraction):

[0055] Deionized water: 75 parts

[0056] Composite silica particles: 4 parts (spherical particles 1-5 μm: porous particles 10-50 μm = 1:0.5)

[0057] Fluorosilicone coupling agent: 0.3 parts

[0058] Thermosensitive polymer microspheres: 1.0 part (Ganzpearl GP-200, Tg = 40°C)

[0059] Epoxy modified silica sol: 1.5 parts

[0060] Ionic liquid antistatic agent (EMIM-BF4): 0.1 part

[0061] PVP binder: 0.5 parts

[0062] 2. Preparation of rough surface treatment liquid:

[0063] (1) Add 75 parts of deionized water to a light-proof container;

[0064] (2) Add 0.5 parts of PVP and stir at 600 rpm at 45°C for 30 minutes until dissolved;

[0065] (3) Add composite silica particles, disperse at 2500 rpm for 15 minutes, and ultrasonicate at 400 W for 10 minutes;

[0066] (4) adding epoxy modified silica sol, fluorinated siloxane coupling agent, and antistatic agent in sequence, and stirring at a constant temperature of 45°C for 40 minutes;

[0067] (5) Add thermosensitive microspheres and stir at 300 rpm for 20 minutes at 30°C;

[0068] (6) Filter and remove aggregates ≥100 μm to obtain a suspension.

[0069] 3. Plate preparation:

[0070] (a) The aluminum substrate was electrolytically roughened and anodized (pore size 8 nm), and then coated with a double-layer photosensitive layer (lower layer carboxyl acrylic resin 1.2 g / m 2 , upper layer of phosphate-based polyurethane 0.8g / m 2 ),dry;

[0071] (b) Ultrasonic atomization spraying of rough surface treatment liquid: atomization pressure 0.3 MPa, droplet DV50 = 30 μm, coating speed 15 m / min, wet film thickness 5 μm;

[0072] (c) Step drying: preheat at 70°C for 5 seconds → cure at 110°C for 10 seconds.

[0073] 4. Effect verification:

[0074] Surface roughness Ra = 0.85 μm, maximum peak-to-valley distance ≤ 8 μm;

[0075] Peel force (35°C / 75%RH): 0.45N / m;

[0076] Printing life: 220,000 prints, no micro cracks;

[0077] Volume expansion rate at 50℃: 18%;

[0078] No sticking after 6 months storage (40℃ / 80%RH).

[0079] Example 2

[0080] Adjustments are made based on Example 1:

[0081] 1. Raw material composition (mass fraction):

[0082] Deionized water: 82 parts

[0083] Composite silica particles: 8 parts (spherical: porous = 1:1)

[0084] Fluorosilicone coupling agent: 0.5 parts

[0085] Thermosensitive polymer microspheres: 1.8 parts (Sekisui SI-BG, Tg = 50°C)

[0086] Epoxy modified silica sol: 2.0 parts

[0087] EMIM-BF4: 0.2 parts

[0088] PVP: 2.5 parts

[0089] 2. Preparation of rough surface treatment liquid: same as Example 1

[0090] 3. Plate preparation process adjustment:

[0091] Ultrasonic atomization pressure 0.4MPa, droplet DV50=45μm;

[0092] Coating speed 25m / min, wet film thickness 8μm;

[0093] Step drying: preheat at 75°C for 6 seconds → cure at 115°C for 12 seconds.

[0094] 4. Effect verification:

[0095] Ra = 1.5 μm;

[0096] Peel force (40℃ / 80%RH): 0.32N / m;

[0097] Printing life: 250,000 prints;

[0098] 50℃ expansion rate: 22%;

[0099] Linear expansion coefficient: 85ppm / ℃.

[0100] Example 3

[0101] Adjustments are made based on Example 1:

[0102] 1. Raw material composition (mass fraction):

[0103] Deionized water: 90 parts

[0104] Composite silica particles: 12 parts (spherical: porous = 1:2)

[0105] Fluorosilicone coupling agent: 0.8 parts

[0106] Thermosensitive microspheres: 2.5 parts (Ganzpearl GP-250, Tg = 60°C)

[0107] Epoxy silica sol: 2.5 parts

[0108] EMIM-BF4: 0.3 parts

[0109] PVP: 4.0 parts

[0110] 2. Preparation of rough surface treatment liquid: same as Example 1

[0111] 3. Plate preparation process adjustment:

[0112] Atomization pressure 0.5MPa, droplet DV50=55μm;

[0113] Coating speed 30m / min, wet film thickness 10μm;

[0114] Step drying: preheat at 80℃ for 3 seconds → cure at 120℃ for 15 seconds.

[0115] 4. Effect verification

[0116] Ra = 2.3 μm, porosity 35%;

[0117] Peel force (45°C / 85%RH): 0.78N / m;

[0118] Printing life: 200,000 prints;

[0119] 50℃ expansion rate: 26%;

[0120] The development was defect-free (100% coverage of dissolved areas).

[0121] Comparative Example 1

[0122] No temperature-sensitive microspheres

[0123] Raw materials: Same as Example 2, except that the thermosensitive polymer microspheres are removed and the PVP content is increased to 3.5 parts.

[0124] Effect:

[0125] Peel force (40℃ / 80%RH): 1.8N / m (adhesion);

[0126] After 3 months of storage, the micro-protrusions collapsed, and the linear expansion coefficient was 210ppm / ℃;

[0127] Volume expansion rate at 50℃: only 3%.

[0128] Comparative Example 2

[0129] Single silica

[0130] Raw materials: Same as Example 2, except that the composite silicon dioxide was replaced by an equal amount of spherical particles (particle size 3 μm).

[0131] Effect:

[0132] Ra = 1.6 μm, but particle embedment depth CV = 48%;

[0133] The developed part is not dissolved, and the defect rate is 12%;

[0134] Printing rate: 48,000 prints (micro crack density 25 / cm 2 ).

[0135] Comparative Example 3

[0136] Silicone anti-stick agent alternative

[0137] Raw materials: Same as Example 2, except for removing the composite silica / temperature-sensitive microspheres and adding 3 parts of silicone anti-sticking agent.

[0138] Effect:,

[0139] Photosensitive layer mobility 4.2wt%

[0140] Dot reproducibility deviation is 18%;

[0141] Printing life: 70,000 prints.

[0142] Comparative Example 4

[0143] No-step drying

[0144] Process: Same as Example 2, but with a single drying at 120°C for 15 seconds.

[0145] Effect:

[0146] The rupture rate of thermosensitive microspheres is >40%;

[0147] Surface porosity <10%, hydrophilicity decreases;

[0148] The peel force increased to 1.5 N / m.

[0149] Comparative Example 5

[0150] Untreated substrate

[0151] Process: After the photosensitive layer is dried, it is directly stacked and stored.

[0152] Effect:

[0153] Initial peel force 2.8N / m, complete adhesion under high temperature and high humidity;

[0154] The residual rate of the lining paper fiber after development is 95%.

[0155] Test Example 1

[0156] Surface anti-stick accelerated aging test

[0157] Purpose: To verify the anti-stick durability of the composite fleece structure under extreme conditions

[0158] method:

[0159] Sample grouping:

[0160] Example 2, Comparative Example 1, Comparative Example 3, and untreated plate (Ra<0.5 μm).

[0161] Accelerated aging conditions:

[0162] High temperature and high humidity group: 40℃ / 80%RH, stack pressure 10kg / cm 2 (Simulates a stack of 1000 plates).

[0163] Temperature cycle group: -10℃(4h)→50℃(4h), 20 cycles.

[0164] Detection indicators:

[0165] Peel force: unit N / m

[0166] Surface morphology: SEM observation of micro-protrusion collapse rate (%)

[0167] Adhesion level: Level 0 (no adhesion) → Level 3 (complete adhesion)

[0168] Table 3 Surface anti-stickiness accelerated aging test results

[0169] Group High temperature and high humidity peel strength (N / m) Collapse rate after temperature change Adhesion level Example 2 0.33±0.05* 8％* 0 Comparative Example 1 1.82±0.12 92％ 3 Comparative Example 3 1.05±0.08 45％ 2 Untreated plate 2.75±0.15 100％ 3

[0170] (*P<0.01 vs other groups)

[0171] Table 3 shows that the peel force of Example 2 increased by only 0.01 N / m (coefficient of variation CV = 3.2%) after accelerated aging. This is attributed to the thermosensitive microspheres (GP-200) compensating for environmental stress through volume expansion (+22% at 50°C), maintaining the structural integrity of the microbumps. In contrast, the linear expansion coefficient of Comparative Example 1, due to the lack of microspheres, reached 210 ppm / °C, resulting in structural collapse.

[0172] Test Example 2

[0173] Correlation experiment between printability and development defect rate

[0174] Purpose: To verify the effect of composite particle distribution on printing quality

[0175] method:

[0176] Test equipment:

[0177] Heidelberg Speedmaster XL75 printing press (ink balance value set to 0.8)

[0178] Development unit: Kodak Trendsetter 800 (on-press development parameters: pH 9.2, temperature 25°C)

[0179] Testing process:

[0180] (1) Each plate material is printed 200,000 times, and tested every 50,000 times:

[0181] -Dot gain (ΔE at 50% dots)

[0182] - End of the printing run rate (plate becomes smeared or falls off)

[0183] (2) Analysis of surface defects after development:

[0184] - Laser confocal microscopy (Olympus LEXT OLS5000) scans the density of the undissolved area (dots / cm 2 )

[0185] -Microcrack counting (SEM 500x field of view)

[0186] Table 4. Experimental results on correlation between printability and development defect rate

[0187] Group Dot gain (ΔE) Printing life (10,000 prints) Development defect rate Example 2 3.2±0.3* 25.3* <![CDATA[0 points / cm 2 *]]> Comparative Example 2 8.7±0.9 4.8 <![CDATA[18 dots / cm 2 > Comparative Example 4 5.1±0.5 19.6 <![CDATA[7 dots / cm 2 >

[0188] As shown in Table 4, the development defect rate of Example 2 is much lower than that of Comparative Examples 2 and 4, and the press life is as high as 253,000 prints, indicating that the CTP plate of the present invention has good printing quality.

[0189] Test Example 3

[0190] Electrostatic adsorption pollution simulation experiment

[0191] Purpose: To verify the inhibitory effect of ionic liquid antistatic agent on printing dust

[0192] method:

[0193] Dust simulation environment:

[0194] A2 test dust (particle size 0-80μm)

[0195] The electrostatic generator generates a -15kV electric field (simulating high-speed friction of a printing press)

[0196] Detection:

[0197] Surface dust adsorption (mg / m 2 , XRF elemental analysis)

[0198] Printing white spot defect rate (spectrophotometer detection L* value deviation)

[0199] The results are shown in Table 5 below:

[0200] Table 5 Results of electrostatic adsorption pollution simulation experiment

[0201] Group Dust adsorption capacity White spot defect rate <![CDATA[Example 2 (containing EMIM-BF4)]]> <![CDATA[8.2mg / m 2 *]]> 0.3％* Antistatic agent-free plate <![CDATA[53.6mg / m 2 ]]> 12.7％

[0202] (*P<0.01)

[0203] mechanism:

[0204] EMIM-BF4 ionic liquid forms a conductive network (surface resistivity drops to 10 8 Ω / sq), reducing the electrostatic adsorption energy of dust to 0.8mJ / m 2 (far below the critical value of 5mJ / m 2 ).

[0205] Test Example 4

[0206] Experiment on correlation between surface roughness and development performance

[0207] Purpose: To verify the effect of different Ra values ​​(0.8-2.5μm) on developer permeability and dot reproducibility

[0208] method:

[0209] Test sample:

[0210] Example 1 (Ra=0.85 μm)

[0211] Example 3 (Ra=2.3 μm)

[0212] Comparative Example 2 (single spherical particle, Ra=1.6 μm)

[0213] Commercially available photosensitive plate (Ra≈0.3μm)

[0214] Development Penetration Test:

[0215] Simulated printing press developer unit: pH 9.2 buffer, 25°C

[0216] Add 0.1 mL of developer solution to the plate surface and record the complete wetting time (ms) by high-speed photography (1000 frames / second).

[0217] Dot reproducibility test:

[0218] Platemaking: Kodak Magnus 800 Platesetter (2400dpi)

[0219] Test standard: UGRA / FOGRA digital measurement and control strip (including 1%-99% dots)

[0220] Testing equipment: Techkon SpectroDens spectrodensitometer

[0221] ΔDot = (actual dot area - target dot area) / target dot area × 100%

[0222] The results are shown in Table 6

[0223] Table 6 Surface roughness and development performance correlation test results

[0224]

[0225] (*P<0.05 vs comparative example 2)

[0226] As shown in Table 6, Example 3 is 57% faster than Example 1, and the dot deviation of Example 3 is 5.1%, which exceeds the industry standard of ≤4%. This shows that the higher the Ra value, the higher the development and infiltration speed, but excessive roughness leads to dot enlargement.

[0227] In Example 1 (Ra=0.85 μm), while ensuring the development efficiency (42 ms<< 120 ms for the commercial version), the dot deviation of 2.8% meets the industry standard requirement (ΔDot≤3%).

[0228] Mechanism: Micron-sized pits (aspect ratio 0.3-0.5) form capillary channels, accelerating the penetration of developer.

[0229] Defect control: The composite particle structure makes the microcrack density of Example 1 0 / cm 2 , while Comparative Example 2 produced 12% undissolved area due to uneven embedding.

[0230] In summary, the present invention provides a CTP plate. Compared with traditional plates, its adhesion to the backing paper is ≤0.8N / m, and the development defect is 0. It has good environmental adaptability and an anti-sticking validity period of more than 6 months, which is better than traditional plates. It also has a high printing durability. It can be seen that the present invention provides a low-cost, highly compatible anti-sticking solution for on-machine development CTP plates. It is particularly suitable for printing plants in high temperature and high humidity areas (such as the southeast region), and can significantly reduce backing paper loss (estimated cost reduction of 30%) and equipment downtime rate. In the future, it can be expanded to the fields of flexible printing plates, optical film anti-sticking, etc., to promote the upgrading of green printing technology.

[0231] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A microstructured anti-sticking on-press negative CTP plate, characterized in that: It includes an aluminum-based substrate, a photosensitive layer and a surface anti-sticking layer; the surface anti-sticking layer is formed by curing a rough surface treatment liquid containing inorganic particles, and its surface roughness Ra is 0.8-2.5μm; The rough surface treatment liquid includes, by mass, 75-90 parts of water, 4-12 parts of composite silicon dioxide particles, 0.3-0.8 parts of fluorine-containing silicone coupling agent, 1.0-2.5 parts of thermosensitive polymer microspheres, 1.5-2.5 parts of epoxy-modified silica sol, 0.1-0.3 parts of ionic liquid antistatic agent, and 0.5-4.0 parts of polyvinyl pyrrolidone (PVP) adhesive.

2. The plate material according to claim 1, characterized in that The composite silicon dioxide particles include spherical particles with a particle size of 1-5 μm and porous structure particles with a particle size of 10-50 μm, with a mass ratio of 1:(0.5-2).

3. The plate material according to claim 1, characterized in that The glass transition temperature of the thermosensitive polymer microspheres is 40-60° C., and the volume expansion rate at 50° C. is ≥15%.

4. The plate material according to claim 3, characterized in that The temperature-sensitive polymer microspheres are acrylate copolymer microspheres.

5. The plate material according to claim 1, characterized in that The ionic liquid antistatic agent is 1-ethyl-3-methylimidazolium tetrafluoroborate.

6. The plate material according to claim 1, characterized in that: The rough surface treatment liquid is prepared by the following steps: (1) Add 75-90 parts by mass of deionized water as a dispersion medium into a light-proof container; (2) adding 0.5-4.0 parts of polyvinyl pyrrolidone binder and stirring and dissolving at 40-50°C and 500-800 rpm for 20-40 minutes; (3) Add 4-12 parts of composite silica particles, first disperse at a high speed of 2000-3000 rpm for 10-20 minutes, and then ultrasonicate at a power of 300-500 W and a frequency of 25 kHz for 5-15 minutes; (4) adding 1.5-2.5 parts of epoxy modified silica sol, 0.3-0.8 parts of fluorinated siloxane coupling agent, and 0.1-0.3 parts of ionic liquid antistatic agent in sequence, maintaining a constant temperature of 40-50°C and stirring for 30-60 minutes; (5) Finally, add 1.0-2.5 parts of thermosensitive polymer microspheres and stir at 200-400 rpm for 15-30 minutes at 25-35°C to prevent the microspheres from breaking; (6) Filter to remove aggregates ≥100 μm to obtain a uniform suspension.

7. The plate material according to claim 1, characterized in that The photosensitive layer contains a film-forming resin, which is an acrylic resin containing branched hydrophilic groups. The hydrophilic groups include carboxyl groups, phosphoric acid groups or sulfonic acid groups. The weight-average molecular weight of the resin is 20,000-200,000.

8. The method for preparing a plate according to any one of claims 1 to 7, wherein: The following steps are involved: (a) coating a photosensitive layer on an aluminum substrate and drying it; (b) spraying the matte surface treatment liquid using a reverse gravure coating process, with a coating speed of 10-30 m / min and a wet film thickness of 3-10 μm; (c) Step drying: preheat at 60-80℃ for 3-8 seconds, then cure at 100-120℃ for 5-15 seconds.

9. The method according to claim 8, characterized in that In the step (b), ultrasonic atomization spraying is adopted, the atomization pressure is 0.2-0.5 MPa, and the droplet particle size DV50 is 20-60 μm.

10. Use of the printing plate according to any one of claims 1 to 7 in a high temperature and high humidity environment, wherein the high temperature and high humidity environment has a temperature of ≥35°C and a humidity of ≥70%RH.

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