CN113320308A

CN113320308A - Laser-engraved flexible printing plate and preparation method thereof

Info

Publication number: CN113320308A
Application number: CN202110555025.8A
Authority: CN
Inventors: 高杰亮; 唐雪华; 倪新华
Original assignee: Jiangsu Kangpu Printing Technology Co ltd
Current assignee: Jiangsu Kangpu Printing Technology Co ltd
Priority date: 2021-05-21
Filing date: 2021-05-21
Publication date: 2021-08-31
Anticipated expiration: 2041-05-21
Also published as: CN113320308B

Abstract

The invention discloses a laser engraving flexographic printing plate, which comprises a substrate; an adhesive layer on the substrate; an engraved plate on the adhesive layer; the top ends of the mesh points on the engraving plate are round, the edges of the mesh points are sharp, and the number of the mesh points is greater than or equal to 200. The laser engraving flexible printing plate disclosed by the invention has excellent environmental protection performance in the plate making process.

Description

Laser-engraved flexible printing plate and preparation method thereof

Technical Field

The invention belongs to the technical field of printing, and particularly relates to a laser engraving flexible printing plate and a preparation method thereof.

Background

Flexographic printing is an environmentally friendly printing process using aqueous inks, i.e., water as a solvent. In the printing process, the printing process is environment-friendly, but the traditional plate production process and the process of preparing a machine-printable mature plate from a raw plate without an image use organic solvents, generate organic volatile compounds (VOC) and are not environment-friendly. The invention aims to improve the environmental protection performance in the production process of the flexible plate. The invention adopts a production technology completely different from the flexographic plates on the current market, and develops the flexographic plate made of rubber which is directly engraved by a laser engraving machine.

Disclosure of Invention

In view of the defects of the prior art, the invention uses the laser engraving technology to directly plate, and does not need to use any chemicals, especially harmful chemicals, in the plate making process, thereby greatly improving the environmental protection performance of the flexographic plate making.

To achieve the above object, the present invention provides a laser engraved flexographic printing plate comprising:

a substrate;

an adhesive layer on the substrate;

an engraved plate on the adhesive layer;

the top ends of the mesh points on the engraving plate are round, the edges of the mesh points are sharp, and the number of the mesh points is greater than or equal to 200.

In one embodiment, the engraving has a maximum elongation L (%) at 25 ℃ tensile break of greater than or equal to 350.

In one embodiment, the thickness of the engraving plate is 0.8-1.2 mm.

In one embodiment, the engraving plate has a tensile strength of 100kgf/cm or more and an elongation at break of 4.5% or less.

In one embodiment, the substrate is made of polyethylene terephthalate, and the substrate is transparent.

In one embodiment, the adhesion between the adhesive layer and the engraving plate is 1.0-2.0N/mm.

In one embodiment, the engraved image-text dot height of the engraving plate can reach 50% of the total thickness of the laser engraved flexible printing plate.

The invention also provides a preparation method of the flexographic printing plate, which at least comprises the following steps:

step 1, pressing the bonding layer on the substrate;

step 2, pressing the carving template on the bonding layer, and performing vulcanization treatment;

and 3, engraving a pattern on the engraving template by using laser to obtain the engraving plate, and preparing the flexographic printing plate.

In one embodiment, in the step of engraving a pattern on the engraving template by using a laser, the laser power is 50-500KW, and the engraving depth is 0.06-0.12 mm.

In one embodiment, the material of the engraving template includes one or more combinations of water-based ink, nitrile oxide or its compound, white carbon black, epoxy resin, natural rubber, titanium white stone, distilled water, montmorillonite, 5-di-tert-butyl peroxy-2, 5-dimethyl hexane, water-dispersible resin, nano-material and cross-linking agent.

In one embodiment, the nano material is one or more of nano silicon dioxide, nano aluminum oxide and nano titanium dioxide.

In one embodiment, the crosslinking agent is an ammonium salt compound.

In one embodiment, the material of the adhesive layer includes:

in still other embodiments, the present disclosure also provides a flexographic printing plate comprising:

a base layer;

a bonding layer on the base layer;

a functional layer on the bonding layer;

an engraving layer on the functional layer;

the top ends of the screen points on the carving layer are round, the edges of the screen points are sharp, and the number of the screen points is more than or equal to 200;

wherein the printing resistance of the engraving layer is 80-100 million prints;

wherein the Shore A hardness of the carving layer is 88-95 degrees.

In one embodiment, the functional layer comprises a shock absorbing layer or a compression resistant layer or a cushioning layer.

In one embodiment, the functional layer is a rubber layer.

In one embodiment, the adhesion between the functional layer and the engraved layer is 1.0-2.0N/mm, and the adhesion between the bonding layer and the functional layer is 1.0-2.0N/mm.

In one embodiment, the material of the engraving layer comprises one or more of ethylene propylene diene monomer, nitrile rubber, a nano material, zinc chloride, stearic acid, a plasticizer TP-90B, light calcium carbonate, an anti-aging agent, a coupling agent and a crosslinking agent.

In one embodiment, the material of the engraving layer comprises one or more of 50-100 parts by mass of ethylene propylene diene monomer, 20-50 parts by mass of nitrile rubber, 2-10 parts by mass of nano material, 5-10 parts by mass of zinc chloride, 10-15 parts by mass of stearic acid, 8-12 parts by mass of plasticizer TP-90B, 2-8 parts by mass of light calcium carbonate, 1.5-10.5 parts by mass of anti-aging agent, 5-10 parts by mass of coupling agent and 10-18 parts by mass of crosslinking agent.

In one embodiment, the nano material is one or more of nano aluminum silicate powder, nano polymethacrylate, carbon nano tube, graphene material, nano silicon dioxide and nano aluminum oxide.

In one embodiment, the coupling agent is a grafted sulfonic acid monoalkoxy titanate coupling agent, an organosilane coupling agent, or a titanate coupling agent.

In one embodiment, the flexographic printing plate has a thickness of 1.14 to 1.70 millimeters.

In one embodiment, the thickness of the engraving layer is 0.8-1.2 mm.

In an embodiment, the engraving layer thickness is not less than 70% of the flexographic printing plate thickness.

In addition, the application also relates to a preparation method of the flexographic printing plate, which at least comprises the following steps:

s1, pressing the bonding layer on the base layer;

s2, pressing the functional layer on the bonding layer, and performing vulcanization treatment;

s3, pressing the carving template on the functional layer, and performing vulcanization treatment;

and S4, engraving a pattern on the engraving template by using laser to obtain the engraving layer, namely preparing the flexographic printing plate.

In step S3, a three-roll calender is used to press-fit the engraving template on the functional layer, the temperatures of three rollers of the three-roll calender are 75-85 ℃, 70-80 ℃ and 50-60 ℃ in sequence, and the pressures of the three rollers are all 8-12 mpa.

According to the invention, on one hand, the use rate of the organic solvent is greatly reduced by applying the calendering technology to the preparation process of the flexographic printing plate, and on the other hand, the laser engraving technology is used for computer-to-plate, and no chemicals, especially harmful chemicals, are required to be used in the plate making process, so that the environmental protection performance of the flexographic plate making is greatly improved. The invention greatly improves the hardness and the fire resistance of the flexible printing plate by adding the matching effect of nano materials such as nano silicon dioxide, nano aluminum dioxide and the like and rubber components. The raised dots on the engraving layer or the engraving plate have sharp edges and regular dots, and have better ink transmission performance than the dots with fuzzy and irregular edges on the traditional flexographic plate. The number of the halftone dots is more than or equal to 200, and the halftone dots are in a high level in China. The carving process adopts the process of rough carving and fine carving, which greatly simplifies the carving process, because the prior carving process adopts the fine carving which is adopted at the beginning and the carving is carried out sequentially, which has no good effect on the final product performance. The invention has the advantages of environment-friendly raw materials, good printing effect, high printing precision (the plate-making precision can reach more than 200 lpi), understandable principle and the like.

Drawings

FIG. 1 is a schematic view of an application scenario of the flexographic printing plate according to an embodiment of the present invention;

FIG. 2 is a schematic view of a four-layer flexographic printing plate according to an embodiment of the present invention;

FIG. 3 is a schematic view of a three-layer flexographic printing plate according to an embodiment of the present invention;

FIG. 4 is a schematic flow chart of the preparation of the flexographic printing plate in one embodiment of the present invention.

Detailed Description

The present invention is further illustrated by the following specific examples, but it should be noted that the specific material ratios, process conditions, results, etc. described in the examples of the present invention are only for illustrating the present invention and should not be construed as limiting the scope of the present invention, and all equivalent changes and modifications made according to the spirit of the present invention should be covered by the scope of the present invention. Note that "%" shown in the description herein means "part by mass" unless otherwise specified.

As used herein, the singular forms "a", "an" and "the" include the plural forms unless the context clearly dictates otherwise. Thus, for example, reference to "a compound" includes a plurality of such compounds, and reference to "a component" or "an additive" means that one or more components or additives, and equivalents thereof, and the like, known to those skilled in the art can be employed.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice of the present invention, the preferred methods, devices, and materials are described below. All publications mentioned herein are intended to describe and disclose the various layers, compounds, compositions, methods, and the like, which are reported in the publications and which may be used in connection with the invention. In the present invention, the "min" appearing means "minute".

As shown in fig. 1, the flexographic printing process is a method of transferring ink through an anilox roller 101 to perform printing. Specifically, the image-text part of the flexographic printing plate 20 is raised, the flexographic printing plate 20 is coated on a plate cylinder 106, during printing, an ink layer with a certain thickness is uniformly coated on the image-text part of the flexographic printing plate 20 by the anilox roller 101, the anilox roller 101 is provided with ink by an ink form roller 104, the amount of the ink is controlled by a scraper 105 at one end of the anilox roller 101, then under the pressure of the impression cylinder 102, the plate cylinder 106 transfers the ink layer of the image-text part to the surface of a printing stock 103 to form a clear image-text, and the printing stock 103 is paper or cloth for example, or other materials.

As shown in fig. 2, the flexographic printing plate 20 provided by the present invention includes, for example, four layers, a base layer 201, an adhesive layer 202, an engraved layer 203, and a functional layer 204, the adhesive layer 202 being located on the base layer 201, the functional layer 204 being located on the adhesive layer 202, and the engraved layer 203 being located on the functional layer 204. The functional layer 204 is, for example, a shock absorption layer, a pressure-resistant layer or other functional layers, such as a rubber layer, and the functional layer plays a role in buffering, so that the pressure applied to the engraved layer in the transfer process can be relieved, the deformation of the engraved layer can be reduced, and the image with fine dots can be transferred clearly.

As shown in fig. 3, the flexographic printing plate 20 provided by the present invention includes, for example, three layers, a substrate 301, an adhesive layer 302, and an engraved layer 303, the adhesive layer 302 being located on the substrate 301, and the engraved layer 303 being located on the adhesive layer 302. In the flexographic printing plate 20 shown in fig. 2 and 3, the characteristics of the substrate 301 determine the characteristics of the adhesive layer 302, and the formulation composition of the adhesive layer 302 varies depending on the substrate 301.

Because a functional layer 204 is added in fig. 2, the flexographic printing plate shown in fig. 2 and the flexographic printing plate shown in fig. 3 are two completely different products, and the formulation ratio of each layer is different, and the performance characteristics of each layer are completely different.

As shown in fig. 2 and 3, the maximum elongation L (%) of the engraved layer 203 at 25 ℃ tensile break is 350 or more, specifically, for example, 350, 400, 450, 480, 500, 520. The tensile strength of the carving layer 203 is more than or equal to 100kgf/cm, and the elongation at break is less than or equal to 4.5%. The maximum elongation L (%), the tensile strength and the elongation at break of the engraved layer 203 are the effects achieved by the components in the engraved layer 203 through the synergistic effect under the process conditions of the present invention.

As shown in fig. 2 and 3, the thickness of the engraving layer 203 is, for example, 0.8 to 1.2 mm, specifically, 0.8 mm, 0.85 mm, 0.90 mm, 0.10 mm, or 1.2 mm. The thickness of the flexographic printing plate 20 is the sum of the thicknesses of the base layer 201, the adhesive layer 202, and the engraved layer 203, or the sum of the thicknesses of the base layer 201, the adhesive layer 202, the engraved layer 203, and the functional layer 204, and is, for example, 1.14 to 1.70mm, and further, for example, 1.14mm, 1.50mm, and 1.70mm, and therefore, the flexographic printing plate 20 has a desirable strength and is not easily deformed. Further, the amount of change in the thickness of the flexographic printing plate 20 is, for example, 0.03mm or less, for example, 0.01mm, 0.02mm or 0.03 mm. The engraving laser power is 50-500KW, specifically, for example, 50KW, 100KW, 250KW, 300KW, 500KW, and the engraving depth is 0.06-0.12mm, specifically, for example, 0.06mm, 0.08mm, 0.10 mm, 0.12 mm.

As shown in fig. 2 and 3, the top of the dot on the engraved layer 203 is rounded, the edge of the dot is sharp (sharp), the number of lines of the dot is greater than or equal to 200 lines, and the ink transfer performance and the printing quality are very good. The engraving layer 203 has a very high printing durability, and the printing durability of the engraving layer 203 is 80 to 100 million prints, specifically, for example, 80, 85, 90, 95, and 100 million prints. The engraving layer 203 has a shore a hardness of, for example, 88 ° -95 °, such as 88 °, 90 °, 95 °; has a tensile strength of 100KN/m or more, further 110KN/m or more, for example 110KN/m, 115KN/m, 118 KN/m; has an elongation of 4.5% or less, further 3.0% or less, such as 3.0%, 2.0%, 1.0%, and has a compressibility of 0.05 to 0.17mm, such as 0.05mm, 0.16mm, 0.17mm, more specifically, in some embodiments, the flexographic printing plate 20 has a compressibility of 0.05 to 0.12mm under a print load of 800-1500Kpa, such as 900Kpa, 1000Kpa, 1060Kpa, and the flexographic printing plate 20 has a compressibility of 0.10 to 0.17mm under a print load of 1800-2500Kpa, such as 2060Kpa, 2100Kpa, 2300 Kpa. The adhesion between the adhesive layer 202 and the engraved layer 203 is 1.0 to 2.0N/mm, and further, for example, 1.0N/mm, 1.5N/mm, 1.8N/mm.

The adhesive layer 202 and the engraving layer 203 have different formulations, and the adhesion between the adhesive layer 202 and the engraving layer 203 can ensure the stability of the whole flexographic printing plate 20, thereby being beneficial to the engraving plate making process at the later stage and avoiding the fracture caused by radial stress in the using process. The tie layer 202 may be, for example, an anaerobic adhesive such as butyl acrylate and C2-C10 alkyl esters of acrylic acid; epoxy resins, for example one-component resin adhesives, such as dicyandiamide (cyanoguanidine), or two-component systems using polyfunctional amines or polyfunctional acids as curing agents, or using cyanoacrylates; or a hot melt adhesive such as polyethylene, polyvinyl acetate, polyamide, hydrocarbon resin, resinous material, and wax, and may also be a pressure sensitive adhesive.

The material of the adhesive layer 302 may include, for example: 120 parts of 105-one nitrile rubber 6250, 10-35 parts of white carbon black, 0.5-1 part of kh-550, 0.5-1 part of coupling agent SI-69, 5-7 parts of TP-90B, 3-5 parts of zinc oxide, 0.5-1 part of antioxidant 2246, 1-1.5 parts of stearic acid, 0.5-1 part of sulfur powder, 0.5-1 part of AB-30, 0.8-1 part of accelerant TT and 0.5-1 part of accelerant CBS. The thickness of the adhesive layer 202 is, for example, 0.2mm to 0.4mm, such as 0.2mm, 0.25mm, 0.3mm, 0.4 mm. The formula components of the adhesive layer 302 are different with the change of the substrate 301, when the content of the nitrile rubber 6250 in the adhesive layer is 105-120 parts by mass, the adhesive layer prepared is high in adhesion with the engraving plate, and the white carbon black exists in the nitrile rubber in an aggregate form, the aggregate form and the nitrile rubber cooperate to enhance the adhesion, so that the nitrile rubber has better elasticity, and the nitrile rubber of 105-120 parts by mass enables the adhesive layer to have proper hardness, so that the adhesive layer has a buffering effect while ensuring proper hardness, the pressure on the engraving plate in the unloading and transferring process reduces the deformation of the engraving plate, and the image of fine mesh points can be clearly transferred.

As shown in fig. 2 and 3, the base layer 201 is made of, for example, polyethylene terephthalate, the base layer 201 is transparent, the base layer 201 serves as a support frame of the flexographic printing plate 20, and the base layer 201 is, for example, a long-staple cotton cloth, a hemp cloth, a non-woven fabric, or the like. The adhesive layer 202 includes, for example, microspheres, specifically, microspheres, a rubber component, an auxiliary agent, and the like. Further, the microspheres form a fully closed cell structure after vulcanization foaming, the cells are fully closed cells with a diameter of, for example, 1-100 μm, further, for example, 5-30 μm, for example, 10 μm, 13 μm, the cells are uniform and complete, the average porosity is 70-80%, and the bonding layer 202 has a compression distance of 0.12-0.24mm under a load of 800-1500Kpa, for example; the compression distance is 0.20-0.24mm under the load of 1800-2500Kpa, which ensures that the micro-holes absorb the printing pressure during the printing process to prevent the surface of the flexographic printing plate 20 from bulging, causing dot deformation, and the micro-holes recover rapidly after the printing pressure is removed, so that the pressure during the printing process is kept constant basically.

In some embodiments, the microspheres may be a polyurethane microsphere blowing agent, the polyurethane microspheres comprising a polyurethane shell and a gas encapsulated therein, forming tiny spherical plastic particles, which soften when heated and expand the gas within the shell, causing the expanded microspheres to increase in volume and become a 100% enclosure and return to their original volume after the pressure is released. The polyurethane microsphere foaming agent has a foaming temperature of, for example, 80-190 ℃ and a diameter of, for example, 0.7-1.4. mu.m, such as 0.8. mu.m, 1 μm. The microspheres may be formed from acrylonitrile or a copolymer of acrylonitrile, and further include isobutane, 2, 4-dimethylbutane, 2-methylpentane, 3-methylpentane, n-hexane, cyclohexane, heptane, isooctane or any combination thereof in the raw material components of the microspheres, and may be other suitable polymeric microspheres, such as those prepared by emulsion polymerization, emulsified to obtain polymeric particles, and then screened and dried to obtain the microspheres, wherein the polymeric particles may have an average particle diameter of 0.02-0.05mm, such as 0.03, 0.04 mm. Sample microspheres of similar average particle size were obtained by sieving, and the effect of particle size non-uniformity on expansion in use of the flexographic plate was limited.

In some embodiments, the microspheres may also include, for example, rubber components such as acrylonitrile/butadiene rubber (NBR), neoprene (CR), fluoro-rubbers (FKM), Urethanes (UR), ethylene propylene rubbers (EPDM), butyl rubbers (IIR), and fillers, aids, and fillers. In some embodiments, the adjuvants are, for example, vulcanizing agents, antioxidants, reinforcing agents, fillers, plasticizers, and the like. Such as carbon black, white carbon, silica, titanium dioxide, calcium carbonate, colored pigments, clays, and combinations thereof, and reinforcing agents such as zinc stearate and/or zinc oxide.

When the flexographic printing plate has four layers, as shown in fig. 2, in some embodiments, the engraving layer 203 is made of one or more of ethylene propylene diene monomer, nitrile rubber, nano-material, zinc chloride, stearic acid, plasticizer TP-90B, light calcium carbonate, anti-aging agent, coupling agent, and crosslinking agent. Specifically, the carving layer 203 comprises one or more of 50-100 parts by mass of ethylene propylene diene monomer, 20-50 parts by mass of nitrile rubber, 2-10 parts by mass of nano material, 5-10 parts by mass of zinc chloride, 10-15 parts by mass of stearic acid, 8-12 parts by mass of plasticizer TP-90B, 2-8 parts by mass of light calcium carbonate, 1.5-10.5 parts by mass of anti-aging agent, 5-10 parts by mass of coupling agent and 10-18 parts by mass of crosslinking agent. The nano material is, for example, one or more of nano aluminum silicate powder, nano polymethacrylate, carbon nano tubes, graphene materials, nano silicon dioxide and nano aluminum oxide, and the rubber content in the engraving layer 203 ensures the hardness of the engraving layer 203.

Specifically, the roughness of the engraving layer 203 can be reduced by the coordination of the nano aluminum silicate powder and the nano polymethacrylate, which is beneficial to the subsequent engraving process. The nano silicon dioxide can greatly improve the hardness of the carving layer 203, the nano aluminum oxide also greatly improves the flame retardance of the carving layer 203, and the addition of the nano aluminum oxide can also improve the wear resistance and fracture toughness of the carving layer 203. The nano alumina is used in an amount of, for example, 3 to 4 parts by mass (or parts by weight). The hardness and flame retardancy of the engraved layer 203 are not caused only by the addition of the individual components but also by the synergistic effect of the nano-silica or nano-alumina and the rubber component. The nano material is also carbon nano tube or graphene, when the nano material is carbon nano tube or graphene, the dosage relation among the carbon nano tube, the graphene and the ethylene propylene diene is 1/5-1/9 of the dosage of the ethylene propylene diene, and the dosage relation among the carbon nano tube, the graphene and the nitrile rubber is 1/10-1/5 of the dosage of the nitrile rubber.

Referring to fig. 3, when the flexographic printing plate has three layers, in other embodiments, the material of the engraving layer 303 includes one or more combinations of water-based ink, nitrile oxide or its compound, white carbon black, epoxy resin, natural rubber, titanium white stone, distilled water, montmorillonite, 5-di-tert-butylperoxy-2, 5-dimethylhexane, water-dispersible resin, nano-materials, and cross-linking agent. Specifically, for example, 60 to 90 parts by mass of water-based ink, 10 to 15 parts by mass of nitrile oxide or a compound thereof, 2 to 8 parts by mass of white carbon black, 4 to 10 parts by mass of epoxy resin, 10 to 20 parts by mass of natural rubber, 5 to 8 parts by mass of titanium white stone, 15 to 25 parts by mass of distilled water, 8 to 12 parts by mass of 5-di-tert-butylperoxy-2, 5-dimethylhexane, 5 to 6 parts by mass of a nanomaterial and 10 to 20 parts by mass of a crosslinking agent are mixed. The nano material is one or more of nano silicon dioxide, nano aluminum oxide and nano titanium dioxide. The nano silicon dioxide is powder, and the powder particle fineness is specifically 1500-2500 meshes.

As shown in fig. 3, the top of the dot on the engraving layer 303 is circular, the edge of the dot is sharp, the number of the dots is greater than or equal to 200, the dots are regular, and the dot structure is more beneficial to ink transfer in the later period.

Referring to fig. 4, in one embodiment, the method for preparing a flexographic printing plate at least comprises the following steps:

s1, pressing the bonding layer on the substrate;

s2, pressing the carving template on the bonding layer, and vulcanizing;

and S3, engraving patterns on the engraving template by utilizing laser to obtain the engraving plate, namely obtaining the flexographic printing plate.

Specifically, the manufacturing method is applicable to both the four-layer flexographic printing plate shown in fig. 2 and the three-layer flexographic printing plate shown in fig. 3. The method applies the calendering process to the plate making process of the flexible printing plate, greatly reduces the use rate of organic solvent, and simultaneously improves the printing quality of the flexible printing plate.

Specifically, as shown in fig. 4, in steps S1 to S3, the adhesive layer 302 is pressed on the substrate 301 by a calendaring apparatus, the engraving template is pressed on the adhesive layer 302, the engraving template is in a state before engraving, and the material of the engraving template includes one or more of water-based ink, nitrile oxide, white carbon black, epoxy resin, natural rubber, titanium white stone, distilled water, 5-di-tert-butylperoxy-2, 5-dimethylhexane, a nanomaterial, and a cross-linking agent. The invention uses the water-based ink, obviously reduces the discharge amount of VOC (volatile organic compounds), thereby preventing atmospheric pollution, improving the printing operation environment and being beneficial to the health of workers. The water-based ink can completely eliminate the harm of certain toxic and harmful substances in the solvent-based ink to human bodies and the pollution to packaged products, improves the overall environmental quality, and is particularly suitable for packaging printed products with strict requirements on sanitary conditions such as food, beverage, medicines and the like. In addition, the method not only can reduce the fire hazard and hidden danger caused by static electricity and flammable solvent, but also can reduce the residual solvent smell on the surface of the printed matter.

Specifically, the cross-linking agent required by the material of the engraving template is, for example, a mixture of a plurality of cross-linking agents, for example, the cross-linking agent in the present application is cooperated with 5-di-tert-butylperoxy-2, 5-dimethylhexane to generate a three-dimensional network structure, which is beneficial to performing a laser engraving process at a later stage. One of the crosslinking agents is, for example, a polymer of an alkane group containing a crosslinkable group such as a hydroxyl group, a carboxylic acid group, an amine group, an aliphatic group, a siloxy group, an acyl group, an alkenyl group, an epoxy group, or the like. The cross-linking agent is for example also selected from oligomeric or polymeric materials comprising hydroxyl groups as functional groups, and the polymeric or oligomeric materials are selected from acrylic resins, polyester resins, alkyd resins, polyurethane resins, epoxy resins, vinyl resins, polyether polyols, the polymeric or oligomeric materials having hydroxyl values of for example 10-100 mg/g.

Specifically, in steps S1 to S3, the calendering device is, for example, a three-roll calender, and the parameters, such as the temperature, for the subsequent base material in the pressing process are 50 to 85 ℃, for example, the temperatures of three rollers of the three-roll calender are 75 to 85 ℃, 70 to 80 ℃ and 50 to 60 ℃ respectively; the pressure is 8-12MPa, such as 8.0MPa, 8.5MPa, 10MPa, 12 MPa; the roller spacing is 0.05-1mm, e.g. 0.06mm, 0.08mm, 0.09 mm; the calendering rate is from 0.4 to 1.0m/min, for example 0.5m/min, 0.6m/min, 0.8 m/min.

Specifically, in step S3, after the vulcanization treatment is performed, a sulfur-based bond is formed between each layer, and the vulcanization parameters of the vulcanization step are as follows, such as the vulcanization pressure is 0-0.1kg, the vulcanization temperature is, for example, 150-155 ℃, and the vulcanization time is 3-4 minutes. In a specific embodiment, wherein the vulcanization pressure is 0kg, the vulcanization temperature is, for example, between 140 ℃ and 150 ℃, and the vulcanization time is 4-5 minutes.

Examples

The present invention will be described in more detail below with reference to examples and comparative examples.

To provide the engraved layer, 6 examples and 2 comparative examples were prepared according to the parameters in tables 1-2 below.

Example 1

Take as an example a three layer laser engraved flexographic printing plate as shown in figure 3.

60 parts by mass of water-based ink, 10 parts by mass of nitrile oxide or a compound thereof, 2 parts by mass of white carbon black, 4 parts by mass of epoxy resin, 10 parts by mass of natural rubber, 5 parts by mass of whitlockite, 15 parts by mass of distilled water, 5 parts by mass of montmorillonite, 8 parts by mass of 5-di-tert-butylperoxy-2, 5-dimethylhexane, 7 parts by mass of water-dispersed resin, 5 parts by mass of nano-silica, 5 parts by mass of nano-alumina and 10 parts by mass of a crosslinking agent are mixed and kneaded, for example, at a mixing speed of 150-.

In this way, an adhesive layer a was obtained, the formulation of which included: 105 parts by mass of nitrile butadiene rubber 6250, 10 parts by mass of white carbon black, 0.5 part by mass of kh-550, 0.5 part by mass of coupling agent SI-69, 5 parts by mass of TP-90B, 3 parts by mass of zinc oxide, 0.5 part by mass of antioxidant 2246, 1 part by mass of stearic acid, 0.5 part by mass of sulfur powder, 0.5 part by mass of AB-30, 0.8 part by mass of accelerator TT and 0.5 part by mass of accelerator CBS, pressing the bonding layer A on the substrate A by a calender, pressing the engraving template A on the bonding layer A, and carrying out vulcanization treatment. And finally, performing laser engraving on the engraving template A by using laser engraving equipment to obtain an engraving plate A, and further obtaining a laser engraving flexographic printing plate A.

Example 2

90 parts by mass of water-based ink, 15 parts by mass of nitrile oxide or a compound thereof, 8 parts by mass of white carbon black, 10 parts by mass of epoxy resin, 20 parts by mass of natural rubber, 8 parts by mass of whitlockite, 25 parts by mass of distilled water, 2 parts by mass of montmorillonite, 12 parts by mass of 5-di-t-butylperoxy-2, 5-dimethylhexane, 3 parts by mass of water-dispersed resin, 5 parts by mass of nano-silica, 5 parts by mass of nano-alumina and 20 parts by mass of a crosslinking agent are mixed and kneaded, for example, at a mixing speed of 150-.

In this way, an adhesive layer B was obtained, the formulation of which included: 110 parts by mass of nitrile butadiene rubber 6250, 25 parts by mass of white carbon black, 0.7 part by mass of kh-550, 0.7 part by mass of coupling agent SI-69, 6 parts by mass of TP-90B, 4 parts by mass of zinc oxide, 0.7 part by mass of antioxidant 2246, 1.0 part by mass of stearic acid, 0.7 part by mass of sulfur powder, 0.7 part by mass of AB-30, 0.9 part by mass of accelerator TT and 0.6 part by mass of accelerator CBS, pressing the bonding layer B on the substrate B by a calender, pressing the engraving template B on the bonding layer B, and performing vulcanization treatment. And finally, performing laser engraving on the engraving template B by using laser engraving equipment to obtain an engraving plate B, and further obtaining a laser engraving flexible printing plate B.

Example 3

85 parts by mass of water-based ink, 15 parts by mass of nitrile oxide or a compound thereof, 8 parts by mass of white carbon black, 10 parts by mass of epoxy resin, 20 parts by mass of natural rubber, 8 parts by mass of whitlockite, 25 parts by mass of distilled water, 3 parts by mass of montmorillonite, 12 parts by mass of 5-di-tert-butylperoxy-2, 5-dimethylhexane, 4 parts by mass of water-dispersed resin, 5 parts by mass of nano-silica, 5 parts by mass of nano-alumina, 5 parts by mass of nano-titania and 20 parts by mass of a crosslinking agent are mixed and kneaded, for example, at a mixing speed of 150-.

In this way, a bond coat C was obtained, the formulation of which included: 120 parts by mass of nitrile butadiene rubber 6250, 35 parts by mass of white carbon black, 1 part by mass of kh-550, 1 part by mass of coupling agent SI-69, 7 parts by mass of TP-90B, 5 parts by mass of zinc oxide, 1 part by mass of antioxidant 2246, 1.5 parts by mass of stearic acid, 1 part by mass of sulfur powder, 1 part by mass of AB-30, 1 part by mass of accelerator TT and 1 part by mass of accelerator CBS, pressing the bonding layer C on the substrate C by using a calender, pressing the engraving template C on the bonding layer C, and carrying out vulcanization treatment. And finally, performing laser engraving on the engraving template C by using laser engraving equipment to obtain an engraving plate C, and further obtaining a laser engraving flexible printing plate C.

Comparative example 1

Take as an example a three layer laser engraved flexographic printing plate as shown in figure 3. This comparative example did not incorporate nanomaterials.

85 parts by mass of water-based ink, 15 parts by mass of nitrile oxide or a compound thereof, 8 parts by mass of white carbon black, 10 parts by mass of epoxy resin, 20 parts by mass of natural rubber, 8 parts by mass of whitlockite, 25 parts by mass of distilled water, 12 parts by mass of 5-di-t-butylperoxy-2, 5-dimethylhexane, and 20 parts by mass of a crosslinking agent are mixed and kneaded, for example, at a mixing speed of 150-.

In this way, an adhesive layer D was obtained, the formulation of which comprised: 120 parts by mass of nitrile butadiene rubber 6250, 35 parts by mass of white carbon black, 1 part by mass of kh-550, 1 part by mass of coupling agent SI-69, 7 parts by mass of TP-90B, 5 parts by mass of zinc oxide, 1 part by mass of antioxidant 2246, 1.5 parts by mass of stearic acid, 1 part by mass of sulfur powder, 1 part by mass of AB-30, 1 part by mass of accelerator TT and 1 part by mass of accelerator CBS, pressing the bonding layer D on the substrate D by using a calender, pressing the engraving template C on the bonding layer D, and carrying out vulcanization treatment. And finally, performing laser engraving on the engraving template D by using laser engraving equipment to obtain an engraving plate D, and further obtaining a laser engraving flexible printing plate D.

Example 4

Take a four-layer flexographic printing plate as shown in fig. 2 as an example.

50 parts by mass of ethylene propylene diene monomer, 20 parts by mass of nitrile rubber, 2 parts by mass of nano-aluminum silicate powder, 5 parts by mass of nano-polymethacrylate, 5 parts by mass of zinc chloride, 10 parts by mass of stearic acid, 8 parts by mass of plasticizer TP-90B, 2 parts by mass of light calcium carbonate, 1.5 parts by mass of anti-aging agent, 5 parts by mass of coupling agent and 10 parts by mass of cross-linking agent are mixed and mixed, for example, at the mixing speed of 150 plus 180rpm for 20-30 minutes to prepare a blend, then the blend is pressed into a slab with a certain thickness, and then the slab is kept at the temperature of 140 plus 160 ℃ for 30-40 minutes to prepare an engraving template E.

Obtaining a bonding layer E by the method, and pressing the bonding layer E on a base layer E by a calender to obtain a functional layer E by the method, wherein the functional layer E is prepared from the following materials: 80 parts by mass of nitrile-butadiene rubber, 10 parts by mass of natural rubber, 10 parts by mass of carbon black, 0.1 part by mass of white carbon black, 4 parts by mass of rubber crumbs, 1.5 parts by mass of plasticizer TP-90B, 5 parts by mass of black factice, 1 part by mass of zinc oxide, 0.5 part by mass of stearic acid, 2 parts by mass of resin 100, 0.1 part by mass of antioxidant 2246, 0.1 part by mass of sulfur powder, 1 part by mass of foaming agent f35, 0.2 part by mass of binder AB-30, 0.1 part by mass of accelerator TT, 0.5 part by mass of accelerator CBS, 0.1 part by mass of antiscorching agent CTP, a functional layer E is pressed on the bonding layer E, and a plate E is pressed on the bonding layer E and is vulcanized. And finally, performing laser engraving on the plate material E by using laser engraving equipment to obtain an engraving layer E, and further obtaining a flexible printing plate E.

The adhesive force between the functional layer and the carving layer is 2.0N/mm, and the adhesive force between the bonding layer and the functional layer is 2.0N/mm.

Example 5

Take a four-layer flexographic printing plate as shown in fig. 2 as an example.

70 parts by mass of ethylene propylene diene monomer, 30 parts by mass of nitrile rubber, 5 parts by mass of nano alumina, 7 parts by mass of zinc chloride, 12 parts by mass of stearic acid, 8 parts by mass of plasticizer TP-90B, 4 parts by mass of light calcium carbonate, 5 parts by mass of anti-aging agent, 7 parts by mass of coupling agent and 15 parts by mass of crosslinking agent are mixed and mixed, for example, the mixture is mixed for 20 to 30 minutes at the mixing speed of 150-.

The bonding layer F is obtained by the method, the bonding layer F is pressed on the base layer F by a calender, the functional layer F is pressed on the bonding layer F, and the functional layer G comprises the following raw material components: 85 parts by mass of nitrile-butadiene rubber, 12 parts by mass of natural rubber, 12 parts by mass of carbon black, 0.15 part by mass of white carbon black, 5 parts by mass of rubber crumbs, 1.7 parts by mass of plasticizer TP-90B, 6 parts by mass of black factice, 3 parts by mass of zinc oxide, 0.7 part by mass of stearic acid, 5 parts by mass of resin 100, 0.5 part by mass of antioxidant 2246, 1 part by mass of sulfur powder, 4 parts by mass of foaming agent F35, 0.7 part by mass of binder AB-30, 0.2 part by mass of accelerator TT, 1 part by mass of accelerator CBS and 0.4 part by mass of antiscorching agent CTP, and the plate material F is pressed on the bonding layer F and is vulcanized. And finally, performing laser engraving on the plate material F by using laser engraving equipment to obtain an engraved layer F, and further obtaining the flexible printing plate F.

The adhesive force between the functional layer and the carving layer is 1.5N/mm, and the adhesive force between the bonding layer and the functional layer is 1.5N/mm.

Example 6

Take a four-layer flexographic printing plate as shown in fig. 2 as an example.

100 parts by mass of ethylene propylene diene monomer, 50 parts by mass of nitrile rubber, 5 parts by mass of carbon nano tubes, 4 parts by mass of nano silica, 10 parts by mass of zinc chloride, 15 parts by mass of stearic acid, 10 parts by mass of plasticizer TP-90B, 8 parts by mass of light calcium carbonate, 10 parts by mass of anti-aging agent, 10 parts by mass of coupling agent and 18 parts by mass of crosslinking agent are mixed and kneaded, for example, at a mixing speed of 150-.

Obtaining a bonding layer G by the method, pressing the bonding layer G on a base layer G by a calender, and pressing a functional layer G on the bonding layer G, wherein the functional layer G comprises the following raw material components: 90 parts by mass of nitrile-butadiene rubber, 15 parts by mass of natural rubber, 25 parts by mass of carbon black, 0.2 part by mass of white carbon black, 6 parts by mass of rubber crumbs, 2.5 parts by mass of plasticizer TP-90B, 7 parts by mass of black factice, 4 parts by mass of zinc oxide, 1.2 parts by mass of stearic acid, 7 parts by mass of resin 100, 1.3 parts by mass of antioxidant 2246, 1.2 parts by mass of sulfur powder, 6 parts by mass of foaming agent f35, 1.2 parts by mass of binder AB-30, 0.25 part by mass of accelerator TT, 1.7 parts by mass of accelerator CBS and 0.5 part by mass of antiscorching agent CTP, and the plate G is pressed on the bonding layer G and is vulcanized. And finally, performing laser engraving on the plate G by using laser engraving equipment to obtain an engraved layer G, and further obtaining the flexographic printing plate G.

Comparative example 2

Take a four-layer flexographic printing plate as shown in fig. 2 as an example. The comparative example did not have the addition of ethylene propylene diene monomer, nor the addition of nanomaterials.

50 parts by mass of nitrile rubber, 5 parts by mass of zinc chloride, 10 parts by mass of stearic acid, 8 parts by mass of plasticizer TP-90B, 2 parts by mass of light calcium carbonate, 1.5 parts by mass of anti-aging agent, 5 parts by mass of coupling agent and 10 parts by mass of cross-linking agent are mixed and mixed, for example, the mixture is mixed for 20 to 30 minutes at the mixing speed of 150-.

The bonding layer H is obtained by the method, the bonding layer H is pressed on the base layer H by a calender, the functional layer H (such as a damping layer) is pressed on the bonding layer H, the plate H is pressed on the bonding layer H, and vulcanization treatment is carried out. And finally, performing laser engraving on the plate material H by using laser engraving equipment to obtain an engraved layer H, and further obtaining the flexible printing plate H.

Table 1 formulation parameters for examples 1-3, comparative example 1 engraved layer

Table 2 formulation parameters for examples 4-6, comparative example 2 engraving layers

The plurality of raw material components of the engraved plate 303 in examples 1 to 3 were mixed and tableted by a calendaring apparatus, and after laminating the plurality of raw material components in a sheet form on the substrate 301, the adhesive layer 302, and the engraved plate 303, vulcanization foaming was performed to obtain the flexographic printing plate 20.

Evaluation of

The evaluation items of the flexographic printing plates 20 obtained in examples 1 to 6 and comparative examples 1 to 2 were measured as shown in Table 3.

Specifically, the flexographic printing plate 20 formed by calendering has clear dots, sharp edges, good ink transmission performance and excellent flame retardant performance.

Table 3 evaluation of the properties of flexographic printing plates

In summary, in the invention, on one hand, the use rate of the organic solvent is greatly reduced by applying the calendering technology to the preparation process of the flexographic printing plate, and on the other hand, the laser engraving technology is used for computer-to-plate, so that no chemical, especially harmful chemical, is required to be used in the plate making process, and the environmental protection performance in the plate making process of the flexographic printing plate is greatly improved. The invention greatly improves the hardness, tensile strength and flame retardance of the flexible printing plate by adding the matching effect of nano materials such as nano silicon dioxide, nano aluminum dioxide and the like and rubber components.

The raised dots on the engraving layer are sharp in edge and neat in dot, and have better ink transmission performance than the dots with fuzzy and irregular edges on the traditional flexographic plate. The number of the halftone dots is more than or equal to 200, and the halftone dots are in a high level in China. The carving process adopts the process of rough carving and fine carving, greatly simplifies the carving process, because the existing carving process adopts the fine carving at the beginning and sequentially carves according to the sequence, the product performance is not good, and on the contrary, the rough carving is adopted at the beginning, most of the unnecessary plate materials are carved firstly, and then the required patterns are carved by fine carving. The invention has the advantages of environment-friendly raw materials, good printing effect, high printing precision (the plate-making precision can reach more than 200 lpi), understandable principle and the like.

While the invention has been described with respect to a preferred embodiment, it will be understood by those skilled in the art that the foregoing and other changes, omissions and deviations in the form and detail thereof may be made without departing from the scope of this invention. Those skilled in the art can make various changes, modifications and equivalent arrangements, which are equivalent to the embodiments of the present invention, without departing from the spirit and scope of the present invention, and which may be made by utilizing the techniques disclosed above; meanwhile, any changes, modifications and variations of the above-described embodiments, which are equivalent to those of the technical spirit of the present invention, are within the scope of the technical solution of the present invention.

Claims

1. A laser engraved flexographic printing plate comprising:

a substrate;

an adhesive layer on the substrate;

an engraved plate on the adhesive layer;

2. The laser-engraved flexographic printing plate of claim 1, wherein said engraved plate has a maximum elongation at tensile break L at 25 ℃ of greater than or equal to 350%.

3. The laser-engraved flexographic printing plate of claim 1, wherein said engraving has a thickness of 0.8 to 1.2 millimeters.

4. The laser-engraved flexographic printing plate according to claim 1, characterized in that said engraved plate has a tensile strength of not less than 100kgf/cm and an elongation at break of not more than 4.5%.

5. The laser-engraved flexographic printing plate of claim 1 wherein the height of the engraved image-text dots is at most 50% of the total thickness of the laser-engraved flexographic printing plate.

6. The laser-engraved flexographic printing plate of claim 1 wherein said substrate is a polyethylene terephthalate substrate and said substrate is transparent.

7. The laser-engraved flexographic printing plate of claim 1, wherein the adhesion between said adhesive layer and said engraved plate is 1.0-2.0N/mm.

8. A method of making a laser engraved flexographic printing plate according to any of claims 1 to 7, characterized by at least the following steps:

pressing the bonding layer on the substrate;

pressing a carving template on the bonding layer, and performing vulcanization treatment;

and engraving patterns on the engraving template by using laser to obtain the engraving plate, and preparing the laser engraving flexible printing plate.

9. The method of making a laser engraved flexographic printing plate according to claim 8 wherein in the step of engraving a pattern on said engraved template with a laser, the laser power is 50-500KW and the engraving depth is 0.06-0.12 mm.

10. The method for preparing a laser engraved flexible printing plate according to claim 8, wherein the material of said engraved template comprises one or more combinations of water-based ink, nitrile oxide or its compound, white carbon black, epoxy resin, natural rubber, titanium white stone, distilled water, 5-di-tert-butylperoxy-2, 5-dimethylhexane, nanomaterial and cross-linking agent.

11. The method of claim 8, wherein the nanomaterial is a combination of one or more of nanosilica, and nanosilica.

12. The method of making a laser engraved flexographic printing plate according to claim 8 wherein said crosslinking agent is an ammonium salt based compound.

13. The method of making a laser engraved flexographic printing plate according to claim 8 wherein the composition of said adhesive layer comprises: