CN113320308B

CN113320308B - Laser engraving flexible printing plate and preparation method thereof

Info

Publication number: CN113320308B
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: 2023-08-08
Anticipated expiration: 2041-05-21
Also published as: CN113320308A

Abstract

The invention discloses a laser engraving flexographic printing plate, which comprises a substrate; an adhesive layer on the substrate; an engraving plate positioned 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 lines of the mesh points is greater than or equal to 200 lines. The laser engraving flexible printing plate disclosed by the invention has excellent environmental protection performance in the plate making process.

Description

Laser engraving 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

Flexography is an environmentally friendly printing process using aqueous inks, i.e. water as solvent. The printing process is environment-friendly, but the traditional plate production process and the process of manufacturing the cooked plate which can be printed by the machine from the raw plate without the image are all processes of using organic solvents, generating organic volatile matters (VOC) and are not environment-friendly. The invention improves the environmental protection performance in the production process of the flexible plate and is a main purpose of the invention. The invention adopts a production technology completely different from that of the flexographic plate on the current market, and develops the flexographic plate made of rubber directly engraved by using a laser engraving machine.

Disclosure of Invention

In view of the shortcomings of the prior art, the invention uses the laser engraving technology to directly plate, and no chemical, especially harmful chemical, is needed in the plate making process, thus greatly improving the environmental protection performance of the flexible 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;

pressing an engraving template on the adhesive layer, vulcanizing, engraving patterns on the engraving template by using laser to obtain an engraving plate;

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 lines of the mesh points is greater than or equal to 200 lines;

the carving template is made of 60-90 parts by mass of water-based ink, 10-15 parts by mass of nitrile oxide or a compound thereof, 2-8 parts by mass of white carbon black, 4-10 parts by mass of epoxy resin, 10-20 parts by mass of natural rubber, 5-8 parts by mass of titanium white stone, 15-25 parts by mass of distilled water, 8-12 parts by mass of 5-di-tert-butyl peroxide-2, 5-dimethylhexane, 5-6 parts by mass of nano material, 10-20 parts by mass of cross-linking agent, montmorillonite and water-dispersible resin.

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

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

In one embodiment, the engraved plate has a tensile strength of greater than or equal to 100kgf/cm and an elongation at break of less than or equal to 4.5%.

In an 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 height of the image-text lattice point after the engraving of the engraving plate can be up to 50% of the total thickness of the laser-engraved flexographic printing plate.

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

step 1, pressing the adhesive layer on the substrate;

step 2, pressing the engraving template on the adhesive layer, and performing vulcanization treatment;

step 3, engraving patterns on the engraving template by utilizing laser to obtain the engraving plate, and preparing the flexible printing plate;

In one embodiment, in the method for manufacturing a flexographic printing plate, in the step of engraving the pattern on the engraving plate by using laser, the laser power is 50-500KW, and the engraving depth is 0.06-0.12mm.

In an embodiment, the nanomaterial is one or more of nano-silica, nano-alumina, and nano-titania in combination.

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

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

nitrile rubber 6250105-120

10-35% of white carbon black

Coupling agent kh-5500.5-1

Coupling agent SI-690.5-1

Plasticizer TP-90B5-7

Zinc oxide 3-5

Antioxidant 22460.5-1

Stearic acid 1-1.5

0.5 to 1 percent of sulfur powder

Adhesive AB-300.5-1

Accelerator TT0.8-1

Accelerator CBS0.5-1.

In still other embodiments, the present invention further provides a flexographic printing plate comprising:

a base layer;

a bonding layer on the base layer;

a functional layer located on the adhesive layer;

the engraving layer is positioned on the functional layer;

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

wherein the printing resistance of the engraving layer is 80 ten thousand printing to 100 ten thousand printing;

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

In an embodiment, the functional layer comprises a shock absorbing layer or a compression layer or a buffer layer.

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

In one embodiment, the adhesion between the functional layer and the engraving 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 an embodiment, the material of the carving layer comprises 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 cross-linking agent.

In an embodiment, the material of the carving layer comprises one or more of Ethylene Propylene Diene Monomer (EPDM) 50-100 parts by mass, nitrile rubber 20-50 parts by mass, nano material 2-10 parts by mass, zinc chloride 5-10 parts by mass, stearic acid 10-15 parts by mass, plasticizer TP-90B 8-12 parts by mass, light calcium carbonate 2-8 parts by mass, anti-aging agent 1.5-10.5 parts by mass, coupling agent 5-10 parts by mass and cross-linking agent 10-18 parts by mass.

In an embodiment, the nanomaterial 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 mono-alkoxy 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 engraving layer has a thickness of 0.8-1.2 millimeters.

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 flexible printing plate, which at least comprises the following steps:

s1, laminating the bonding layer on the base layer;

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

s3, pressing the engraving template on the functional layer, and vulcanizing;

and S4, engraving patterns on the engraving template by utilizing laser to obtain the engraving layer, namely preparing the flexible printing plate.

In the step S3, the engraving template is pressed on the functional layer by using a three-roller calender, the temperatures of three rollers of the three-roller calender are 75-85 ℃, 70-80 ℃ and 50-60 ℃ in sequence, and the pressures of the three rollers are 8-12 megapascals.

According to the invention, on one hand, the calendaring technology is applied to the preparation process of the flexographic printing plate, so that the use ratio of the organic solvent is greatly reduced, and on the other hand, the laser engraving technology is used for computer direct plate making, no chemical, especially harmful chemical, is needed in the plate making process, and the environmental protection performance of the flexographic printing plate is greatly improved. The invention greatly improves the hardness and the flame retardance of the flexible printing plate by adding the nano materials such as nano silicon dioxide, nano aluminum dioxide and the like to cooperate with the rubber component. The raised dots on the engraving layer or the engraving plate have sharp edges and regular dots, and have better ink transfer performance than the dots with blurred edges and irregular edges on the traditional flexible plate. The net point line number of the invention is more than or equal to 200 lines and is at a higher level in China. The engraving process of the invention adopts the process of firstly engraving in a rough way and then engraving in a fine way, thus greatly simplifying the engraving process, because the prior engraving process is the fine engraving process adopted at first, the engraving is carried out in sequence, the final product performance is not better, and on the contrary, the invention adopts the rough engraving at first, firstly engraving to remove most of unnecessary plate materials, and then engraving the needed patterns through the fine engraving. 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), easily understood principle and the like.

Drawings

FIG. 1 is a schematic view of an application scenario of a 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 one embodiment of the present invention;

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

fig. 4 is a schematic flow chart of preparing the flexographic printing plate according to an embodiment of the present invention.

Detailed Description

The present invention is further illustrated by the following examples, but it should be noted that the specific material ratios, process conditions, results, etc. described in the examples of the present invention are merely illustrative of the present invention, and are not intended to limit the scope of the present invention, and all equivalent changes or modifications according to the spirit of the present invention should be included in the scope of the present invention. Note that "%" as shown in the description herein means "parts by mass", unless otherwise specified.

As used herein, the singular forms "a," "an," and "the" include 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 known to those skilled in the art, equivalents thereof, and so forth may 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 also be used in the practice of the present invention, the preferred methods, devices, and materials are described below. All publications mentioned herein are provided to describe and disclose the various layers, compounds, compositions, methods, etc. which are reported in the publications and may be used in connection with the present 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 portion of the flexographic printing plate 20 is raised, the flexographic printing plate 20 is coated on a plate cylinder 106, during printing, the anilox roller 101 uniformly coats an ink layer with a certain thickness on the image-text portion of the flexographic printing plate 20, the anilox roller 101 provides ink through an inking roller 104, one end of the anilox roller 101 is provided with ink by a scraper 105, then under the action of the pressure of an impression cylinder 102, the plate cylinder 106 transfers the ink layer of the image-text portion to the surface of a printing stock 103, for example, paper or cloth, or other materials, so as to form clear image-text.

As shown in fig. 2, the flexographic printing plate 20 provided by the present invention comprises four layers, for example, a base layer 201, an adhesive layer 202, an engraving layer 203 and a functional layer 204, wherein the adhesive layer 202 is positioned on the base layer 201, the functional layer 204 is positioned on the adhesive layer 202, and the engraving layer 203 is positioned on the functional layer 204. The functional layer 204 is, for example, a shock-absorbing layer, a compression-resistant layer or other functional layers, for example, a rubber layer, and the functional layers play a role in buffering, so that the pressure applied to the engraving layer in the transfer printing process can be unloaded, the deformation of the engraving layer is reduced, and the image of the fine dots can be transferred clearly.

As shown in fig. 3, the flexographic printing plate 20 provided by the present invention comprises, for example, three layers, a substrate 301, an adhesive layer 302, and an engraving layer 303, wherein the adhesive layer 302 is positioned on the substrate 301, and the engraving layer 303 is positioned on the adhesive layer 302. In flexographic printing plates 20 as shown in fig. 2 and 3, the properties of the substrate 301 determine the properties of the adhesive layer 302, and the formulation composition of the adhesive layer 302 may vary from one substrate 301 to another.

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

As shown in fig. 2 and 3, the maximum elongation L (%) of the engraved layer 203 at 25 ℃ stretch breaking is 350 or more, specifically, for example, 350, 400, 450, 480, 500, 520. The tensile strength of the engraved layer 203 is not less than 100kgf/cm and the elongation at break is not more than 4.5%. The maximum elongation L (%), tensile strength and elongation at break of the engraved layer 203 are effects achieved by the respective components in the engraved layer 203 together through synergistic action 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, 0.8-1.2 mm, specifically, for example, 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 defined as the sum of the thicknesses of the layers of the base layer 201, the adhesive layer 202 and the engraving layer 203, or the sum of the thicknesses of the layers of the base layer 201, the adhesive layer 202, the engraving layer 203 and the functional layer 204, for example, 1.14 to 1.70mm, and further, for example, 1.14mm, 1.50mm and 1.70mm, and based on this, the flexographic printing plate 20 has a desired strength and is not easily deformed. Further, the thickness variation of the flexographic printing plate 20 is, for example, 0.03mm or less, for example, 0.01mm, 0.02mm, or 0.03mm. The engraving laser power is 50-500KW, specifically, for example, 50 KW, 100 KW, 250 KW, 300KW, 500KW, and the engraving depth is 0.06-0.12mm, specifically, for example, 0.06 mm, 0.08 mm, 0.10 mm, 0.12 mm.

As shown in fig. 2 and fig. 3, the top ends of the dots on the engraving layer 203 are round, the edges of the dots are sharp, the number of lines of the dots is greater than or equal to 200, and the ink transfer performance and the printing quality are very good. The engraving layer 203 has a very high print resistance, and the print resistance of the engraving layer 203 is 80 ten thousand prints to 100 ten thousand prints, specifically, for example, 80 ten thousand prints, 85 Mo Yin, 90 ten thousand prints, 95 ten thousand prints, and 100 ten thousand 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 100 KN/m or more, further 110KN/m or more, for example 110KN/m, 115KN/m, 118KN/m; having an elongation of 4.5% or less, further 3.0% or less, such as 3.0%, 2.0%, 1.0%, and having a compressibility of 0.05-0.17mm, such as 0.05mm, 0.16mm, 0.17mm, more particularly, in some embodiments, at a print load of 800-1500Kpa, such as 900Kpa, 1000Kpa, 1060Kpa, the compressibility of the flexographic printing plate 20 is, for example, 0.05-0.12mm, at a print load of 1800-2500Kpa, such as 2060Kpa, 2100Kpa, 2300Kpa, the compressibility of the flexographic printing plate 20 is, for example, 0.10-0.17mm. The adhesion between the adhesive layer 202 and the engraving layer 203 is 1.0-2.0N/mm, further for example 1.0N/mm, 1.5N/mm, 1.8N/mm.

The formulas of the bonding layer 202 and the engraving layer 203 are different, and the adhesive force between the bonding layer 202 and the engraving layer 203 can ensure the stability of the whole flexible printing plate 20, is beneficial to the subsequent engraving plate making process, and avoids fracture caused by radial stress in the use process. The tie layer 202 may employ, for example, an anaerobic adhesive such as butyl acrylate and typically a C2-C10 alkyl ester 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 cyanoacrylates; or hot melt adhesives such as polyethylene, polyvinyl acetate, polyamides, hydrocarbon resins, resinous materials, and waxes, and may also be pressure sensitive adhesives.

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

As shown in fig. 2 and 3, the material of the base layer 201 is, for example, polyethylene terephthalate, the base layer 201 is transparent, the base layer 201 serves as a supporting skeleton of the flexographic printing plate 20, and the base layer 201 is, for example, long-pile cotton cloth, linen, nonwoven 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 microporous structure after vulcanization foaming, the micropores are fully closed micropores with diameters of 1-100 μm, further, for example, 5-30 μm, for example, 10 μm and 13 μm, the pores are uniform and complete, the average porosity is 70-80%, and the compression distance of the bonding layer 202 is 0.12-0.24mm under the load of 800-1500Kpa, for example; under the load of 1800-2500Kpa, the compression distance is 0.20-0.24mm, which ensures that the micro-holes absorb the printing pressure during the printing process, so that the surface of the flexible printing plate 20 does not form bulges to cause the deformation of the dots, and the micro-holes are quickly restored after the printing pressure is eliminated, so that the pressure during the printing process is basically kept constant.

In some embodiments, the microspheres may be polyurethane microsphere blowing agents, the polyurethane microspheres consisting of a polyurethane shell and a gas that it encapsulates, forming tiny spherical plastic particles that upon heating, the polyurethane shell softens, the gas inside the shell expands, such that the expanded microsphere volume increases and is a 100% enclosure, and returns to its original volume upon release of pressure. The polyurethane microsphere blowing agent has a foaming temperature of, for example, 80-190℃and a diameter of, for example, 0.7-1.4. Mu.m, for example, 0.8. Mu.m, 1. Mu.m. Of course, without being limited thereto, the microspheres may also be formed of acrylonitrile or a copolymer of acrylonitrile, and further comprise isobutane, 2, 4-dimethylbutane, 2-methylpentane, 3-methylpentane, n-hexane, cyclohexane, heptane, isooctane or any combination thereof in the raw material component of the microspheres, and the microspheres may also be other suitable polymer microspheres, for example, may be prepared by emulsion polymerization, and after emulsification, polymer particles are obtained, and then sieved and dried, and the average particle size of the polymer particles may be 0.02-0.05mm, for example 0.03, 0.04mm. Sample microspheres of similar average particle size can be obtained by sieving, so that the influence of non-uniformity in particle size on expansibility in offset use can be limited.

In some embodiments, for example, some rubber components, auxiliary agents and fillers are also included in the microspheres, and for example, acrylonitrile/butadiene rubber (NBR), neoprene (CR), fluororubber (FKM), polyurethane rubber (UR), ethylene propylene rubber (EPDM), butyl rubber (IIR), etc. may be used. In some embodiments, the auxiliary agents are, for example, vulcanizing agents, anti-aging agents, 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.

As shown in fig. 2, when the flexographic printing plate is four-layered, in some embodiments, the engraving layer 203 is made of a material such as ethylene propylene diene monomer, nitrile rubber, nanomaterial, zinc chloride, stearic acid, plasticizer TP-90B, light calcium carbonate, an anti-aging agent, a coupling agent, and a cross-linking agent. Specifically, the engraving layer 203 includes one or more of Ethylene Propylene Diene Monomer (EPDM) 50-100 parts by mass, nitrile rubber 20-50 parts by mass, nanomaterial 2-10 parts by mass, zinc chloride 5-10 parts by mass, stearic acid 10-15 parts by mass, plasticizer TP-90B 8-12 parts by mass, light calcium carbonate 2-8 parts by mass, anti-aging agent 1.5-10.5 parts by mass, coupling agent 5-10 parts by mass and cross-linking agent 10-18 parts by mass. The nanomaterial is, for example, one or more of nano aluminum silicate powder, nano polymethacrylate, carbon nano tube, graphene material, 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 coordinated action of the nano aluminum silicate powder and the nano polymethacrylate can reduce the roughness of the engraving layer 203, which is beneficial to the subsequent engraving process. The nano silicon dioxide can greatly improve the hardness of the engraving layer 203, the nano aluminum oxide can also greatly improve the flame retardance of the engraving layer 203, and the addition of the nano aluminum oxide can also improve the wear resistance and fracture toughness of the engraving 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 engraving layer 203 are not merely due to the addition of individual components, but are a result of the synergistic interaction of the nanosilica or the nanosilica 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 relationship among the carbon nano tube, the graphene and ethylene propylene diene monomer is that the dosage of the carbon nano tube and the graphene is 1/5-1/9 of the dosage of the ethylene propylene diene monomer, and the dosage relationship among the carbon nano tube, the graphene and the nitrile rubber is that the dosage of the carbon nano tube and the graphene is 1/10-1/5 of the dosage of the nitrile rubber.

Referring to fig. 3, in other embodiments, the material of the engraving layer 303 includes, for example, one or more of water-based ink, nitrile oxide or a compound thereof, white carbon, epoxy resin, natural rubber, titanium white stone, distilled water, montmorillonite, 5-di-tert-butyl peroxide-2, 5-dimethylhexane, water-dispersible resin, nanomaterial, 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-butyl peroxy-2, 5-dimethylhexane, 5 to 6 parts by mass of nano material and 10 to 20 parts by mass of a crosslinking agent are mixed. The nanomaterial is, for example, one or more of nanosilica, nanosilica alumina, and nanosilica. The nano silicon dioxide is in a powder shape, and the fineness of the powder particles is specifically 1500-2500 meshes.

Referring to fig. 3, the top ends of the dots on the engraving layer 303 are circular, the edges of the dots are sharp, the number of lines of the dots is greater than or equal to 200, the dots are regular, and the dots with such a structure are more beneficial to later ink transfer.

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

s1, laminating the adhesive layer on the substrate;

s2, pressing the engraving template on the adhesive layer, and performing vulcanization treatment;

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

In particular, the preparation 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 calendaring process to the plate making process of the flexible printing plate, greatly reduces the use ratio of the organic solvent and 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 onto the substrate 301 by using a calendaring apparatus, the engraving template is pressed onto the adhesive layer 302, the engraving template is in a state before being engraved, 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-butyl peroxy-2, 5-dimethylhexane, nano material and a cross-linking agent. The invention uses the water-based ink, obviously reduces the discharge amount of VOC (volatile organic compound), thereby preventing the 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 solvent-based ink to human bodies and the pollution to packaging products, improve the overall environmental quality, and is particularly suitable for packaging printed products with strict sanitary conditions such as foods, beverages, medicines and the like. In addition, the method can reduce the fire hazard and hidden danger caused by static electricity and flammable solvents, and can also 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 application cooperates with 5-di-tert-butyl peroxy-2, 5-dimethylhexane to generate a three-dimensional network structure, which is beneficial to the later laser engraving process. One of the crosslinking agents is, for example, a polymer containing an alkane group having a crosslinkable group such as a hydroxyl group, a carboxylic acid group, an amine group, an aliphatic group, a siloxane group, an acyl group, an alkenyl group, an epoxy group, or the like. The crosslinking agent is also selected, for example, from oligomeric or polymeric materials comprising functional groups that are hydroxyl 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 numbers of, for example, 10-100mg/g.

Specifically, in steps S1 to S3, the rolling apparatus is, for example, a three-roll calender, and parameters such as temperatures for subsequent substrates during the lamination process are 50 to 85 ℃, for example, three rolls of the three-roll calender are 75 to 85 ℃, 70 to 80 ℃, and 50 to 60 ℃, respectively; the pressures are all 8-12MPa, for example 8.0 MPa, 8.5 MPa, 10 MPa and 12 MPa; the roller spacing is 0.05-1mm, such as 0.06 mm, 0.08mm, 0.09 mm; the calendering rate is 0.4-1.0 m/min, for example 0.5 m/min, 0.6 m/min, 0.8 m/min.

Specifically, in step S3, after the vulcanization treatment, the sulfide-based bond is formed between each layer, and the vulcanization parameters of the vulcanization step are as follows, for example, the vulcanization pressure is 0 to 0.1kg, the vulcanization temperature is, for example, 150 to 155 ℃, and the vulcanization time is 3 to 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 between 4 and 5 minutes.

Examples

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

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

Example 1

Take the example of a three layer laser engraved flexographic printing plate as shown in fig. 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, 4 parts by mass of epoxy resin, 10 parts by mass of natural rubber, 5 parts by mass of titanium white stone, 15 parts by mass of distilled water, 5 parts by mass of montmorillonite, 8 parts by mass of 5-di-t-butylperoxy-2, 5-dimethylhexane, 7 parts by mass of water-dispersible resin, 5 parts by mass of nano silica, 5 parts by mass of nano aluminum dioxide and 10 parts by mass of a cross-linking agent are mixed and kneaded, for example, at a mixing speed of 150-180rpm for 20-30 minutes to prepare a blend, and then the blend is pressed into a slab with a certain thickness, followed by maintaining at a temperature of, for example, 140-160 ℃ for 30-40 minutes, thereby preparing the engraving template a.

In this way, an adhesive layer a is obtained, the formulation of which comprises: 105 parts by mass of nitrile rubber 6250, 10 parts by mass of white carbon black, 0.5 part by mass of kh-550,0.5 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 parts by mass of stearic acid, 0.5 part by mass of sulfur powder, 0.5 part by mass of AB-30,0.8 parts by mass of accelerator TT and 0.5 part by mass of accelerator CBS, pressing the adhesive layer A on the substrate A by using a calender, pressing the engraving template A on the adhesive layer A, and vulcanizing. Finally, performing laser engraving on the engraving template A by using laser engraving equipment to obtain an engraving plate A, and further obtaining the laser engraving flexographic printing plate A.

Example 2

90 parts by mass of an aqueous ink, 15 parts by mass of a nitrile oxide or a compound thereof, 8 parts by mass of white carbon, 10 parts by mass of an epoxy resin, 20 parts by mass of natural rubber, 8 parts by mass of titanium white stone, 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 a water-dispersed resin, 5 parts by mass of nanosilicon dioxide and 20 parts by mass of a crosslinking agent are mixed and kneaded, for example, at a mixing speed of 150 to 180rpm for 20 to 30 minutes to prepare a blend, after which the blend is pressed into a slab of a certain thickness, and then kept at a temperature of, for example, 140 to 160 ℃ for 30 to 40 minutes, thereby preparing an engraving template B.

In this way, an adhesive layer B is obtained, the formulation of which comprises: 110 parts by mass of nitrile rubber 6250, 25 parts by mass of white carbon black, 0.7 part by mass of kh-550,0.7 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 parts by mass of stearic acid, 0.7 part by mass of sulfur powder, 0.7 part by mass of AB-30,0.9 parts by mass of accelerator TT,0.6 part by mass of accelerator CBS, pressing the adhesive layer B on the substrate B by using a calender, pressing the engraving template B on the adhesive layer B, and vulcanizing. Finally, performing laser engraving on the engraving template B by using laser engraving equipment to obtain an engraving plate B, and further obtaining the laser engraving flexographic 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 titanium white stone, 25 parts by mass of distilled water, 3 parts by mass of montmorillonite, 12 parts by mass of 5-di-t-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 cross-linking agent are mixed and kneaded, for example, at a mixing speed of 150-180rpm for 20-30 minutes to prepare a blend, after which the blend is pressed into a slab of a certain thickness, and then is maintained at a temperature of, for example, 140-160 ℃ for 30-40 minutes, thereby preparing an engraved template C.

In this way, an adhesive layer C is obtained, the formulation of which comprises: 120 parts by weight of nitrile rubber 6250, 35 parts by weight of white carbon black, 1 part by weight of kh-550,1 coupling agent SI-69,7 parts by weight of TP-90B,5 parts by weight of zinc oxide, 1 part by weight of antioxidant 2246,1.5 parts by weight of stearic acid, 1 part by weight of sulfur powder, 1 part by weight of AB-30,1 part by weight of accelerator TT and 1 part by weight 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 vulcanizing. Finally, performing laser engraving on the engraving template C by using laser engraving equipment to obtain an engraving plate C, and further obtaining the laser engraving flexographic printing plate C.

Comparative example 1

Take the example of a three layer laser engraved flexographic printing plate as shown in fig. 3. The comparative example does not incorporate nanomaterials.

85 parts by mass of an aqueous 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 an epoxy resin, 20 parts by mass of natural rubber, 8 parts by mass of titanium white stone, 25 parts by mass of distilled water, 12 parts by mass of 5-di-t-butylperoxy-2, 5-dimethylhexane, 20 parts by mass of a cross-linking agent are mixed and kneaded, for example, at a mixing speed of 150 to 180rpm for 20 to 30 minutes to prepare a blend, after which the blend is pressed into a slab of a certain thickness, and then maintained at a temperature of, for example, 140 to 160 ℃ for 30 to 40 minutes, thereby preparing an engraved template D.

In this way, an adhesive layer D is obtained, the formulation of which comprises: 120 parts by weight of nitrile rubber 6250, 35 parts by weight of white carbon black, 1 part by weight of kh-550,1 coupling agent SI-69,7 parts by weight of TP-90B,5 parts by weight of zinc oxide, 1 part by weight of antioxidant 2246,1.5 parts by weight of stearic acid, 1 part by weight of sulfur powder, 1 part by weight of AB-30,1 part by weight of accelerator TT and 1 part by weight 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 vulcanizing. Finally, performing laser engraving on the engraving template D by using laser engraving equipment to obtain an engraving plate D, and further obtaining the laser engraving flexographic 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 kneaded, for example, at a mixing speed of 150-180rpm for 20-30 minutes to prepare a blend, after which the blend is pressed into a slab of a certain thickness, and then maintained at a temperature of, for example, 140-160 ℃ for 30-40 minutes, thereby preparing an engraving form E.

The method is used for obtaining the bonding layer E, the bonding layer E is pressed on the base layer E by using a calender, and the method is used for obtaining the functional layer E, wherein the materials of the functional layer E comprise: 80 parts of nitrile rubber, 10 parts of natural rubber, 10 parts of carbon black, 0.1 part of white carbon black, 4 parts of rubber crumb, 1.5 parts of plasticizer TP-90B,5 parts of black ointment, 1 part of zinc oxide, 0.5 part of stearic acid, 2 parts of resin 100,0.1 part of antioxidant 2246,0.1 parts of sulfur powder, 1 part of foaming agent f35,0.2 part of adhesive AB-30,0.1 part of accelerator TT,0.5 part of accelerator CBS and 0.1 part of scorch retarder CTP are laminated on the adhesive layer E, the plate E is laminated on the adhesive layer E, and vulcanization treatment is carried out. Finally, performing laser engraving on the plate E by using laser engraving equipment to obtain an engraving layer E, and further obtaining the 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 an anti-aging agent, 7 parts by mass of a coupling agent and 15 parts by mass of a crosslinking agent are mixed and kneaded, for example, at a mixing speed of 150-180rpm for 20-30 minutes to prepare a blend, after which the blend is pressed into a slab of a certain thickness, and then maintained at a temperature of, for example, 140-160 ℃ for 30-40 minutes, thereby preparing a plate F.

The method is characterized in that a bonding layer F is obtained by the method, the bonding layer F is pressed on a base layer F by a calender, a functional layer F is pressed on the bonding layer F, and raw material components of the functional layer G comprise: 85 parts of nitrile rubber, 12 parts of natural rubber, 12 parts of carbon black, 0.15 part of white carbon black, 5 parts of rubber crumb, 1.7 parts of plasticizer TP-90B,6 parts of black ointment, 3 parts of zinc oxide, 0.7 part of stearic acid, 5 parts of resin 100,0.5 part of antioxidant 2246,1 parts of sulfur powder, 4 parts of foaming agent F35,0.7 part of adhesive AB-30,0.2 parts of accelerator TT,1 part of accelerator CBS and 0.4 part of scorch retarder CTP are pressed on the adhesive layer F, and vulcanization treatment is carried out. Finally, the engraving layer F is obtained by utilizing laser engraving equipment to perform laser engraving on the plate F, and then the flexographic printing plate F is obtained.

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 nanotubes, 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 150-180rpm for 20-30 minutes to prepare a blend, after which the blend is pressed into a slab of a certain thickness, and then maintained at a temperature of, for example, 140-160 ℃ for 30-40 minutes, thereby preparing a plate G.

The method is characterized in that a bonding layer G is obtained by the method, the bonding layer G is pressed on a base layer G by a calender, a functional layer G is pressed on the bonding layer G, and the raw material components of the functional layer G comprise: 90 parts of nitrile rubber, 15 parts of natural rubber, 25 parts of carbon black, 0.2 part of white carbon black, 6 parts of rubber crumb, 2.5 parts of plasticizer TP-90B,7 parts of black ointment, 4 parts of zinc oxide, 1.2 parts of stearic acid, 7 parts of resin 100,1.3 parts of antioxidant 2246,1.2 parts of sulfur powder, 6 parts of foaming agent f35,1.2 parts of adhesive AB-30,0.25 parts of accelerator TT,1.7 parts of accelerator CBS and 0.5 part of scorch retarder CTP, and pressing the plate G on the adhesive layer G and vulcanizing. Finally, the engraving layer G is obtained by utilizing laser engraving equipment to perform laser engraving on the plate G, and then the flexographic printing plate G is obtained.

Comparative example 2

Take a four layer flexographic printing plate as shown in fig. 2 as an example. The comparative example was without ethylene propylene diene monomer and without nanomaterial.

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 crosslinking agent are mixed and kneaded, for example, at a mixing speed of 150 to 180rpm for 20 to 30 minutes to prepare a blend, after which the blend is pressed into a slab of a certain thickness, and then maintained at a temperature of, for example, 140 to 160 ℃ for 30 to 40 minutes, thereby preparing a plate H.

The method is characterized in that a bonding layer H is obtained by laminating the bonding layer H on a base layer H by using a calender, a functional layer H (such as a shock absorption layer) is laminated on the bonding layer H, the plate H is laminated on the bonding layer H, and vulcanization treatment is carried out. Finally, performing laser engraving on the plate material H by using laser engraving equipment to obtain an engraving layer H, and further obtaining the flexible printing plate H.

Table 1 formulation parameters of examples 1-3, comparative example 1 engraving layer

Table 2 formulation parameters of examples 4-6, comparative example 2 engraving layer

The flexographic printing plate 20 is obtained by mixing and tabletting the raw material components of the engraving plate 303 of examples 1 to 3 by a rolling apparatus, and vulcanizing and foaming the raw material components in the form of a sheet after pressing the substrate 301, the adhesive layer 302 and the engraving plate 303.

Evaluation

Measurement examples 1-6 and comparative examples 1-2 preparation various evaluation items of the obtained flexographic printing plates 20 are shown in table 3.

Specifically, the calendared flexible printing plate 20 has clear dots, sharp edges, good ink transfer performance and excellent flame retardance.

TABLE 3 evaluation of flexographic printing plate Performance

In summary, according to the invention, on one hand, the use ratio of the organic solvent is greatly reduced by applying the calendaring technology to the preparation process of the flexographic printing plate, and on the other hand, the invention uses the laser engraving technology to carry out computer direct plate making, and no chemical, especially harmful chemical, is needed in the plate making process, so that the environmental protection performance in the flexographic plate making process is greatly improved. The invention greatly improves the hardness, tensile strength and flame retardance of the flexible printing plate by adding the nano materials such as nano silicon dioxide, nano aluminum dioxide and the like to cooperate with the rubber component.

The raised dots on the engraving layer have sharp edges and regular dots, and have better ink transfer performance than the dots with blurred edges and irregular edges on the traditional flexible plate. The net point line number of the invention is more than or equal to 200 lines and is at a higher level in China. The engraving process of the invention adopts the process of firstly engraving in a rough way and then engraving in a fine way, thus greatly simplifying the engraving process, because the prior engraving process is the fine engraving which is adopted at the beginning, and the engraving is sequentially carried out in turn, the invention has no good effect on the final product performance, and on the contrary, the invention adopts the rough engraving at the beginning, firstly engraves most of unnecessary plate materials, and then engraves the needed patterns through the fine engraving. 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), easily understood principle and the like.

While the invention has been described with respect to preferred embodiments thereof, it will be understood by those skilled in the art that various modifications and additions may be made without departing from the scope of the invention. Equivalent embodiments of the present invention will be apparent to those skilled in the art having the benefit of the teachings disclosed herein, when considered in the light of the foregoing disclosure, and without departing from the spirit and scope of the invention; meanwhile, any equivalent changes, modifications and evolution of the above embodiments according to the essential technology of the present invention still fall 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;

2. The laser engraved flexographic printing plate of claim 1, where the maximum elongation L of the engraved plate at 25 ℃ stretch break is greater than or equal to 350%.

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

4. The laser engraved flexographic printing plate of claim 1, where the engraved plate has a tensile strength of equal to or greater than 100kgf/cm and an elongation at break of equal to or less than 4.5%.

5. The laser engraved flexographic printing plate of claim 1, where the height of the dots of the image after engraving of the plate is at most 50% of the total thickness of the plate.

6. The laser engraved flexographic printing plate of claim 1, wherein the substrate is polyethylene terephthalate and the substrate is transparent.

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

8. A method of producing a laser engraved flexographic printing plate according to any one of claims 1 to 7, comprising at least the steps of:

pressing the bonding layer on the substrate;

pressing an engraving template on the adhesive layer, and performing vulcanization treatment;

engraving patterns on the engraving template by utilizing laser to obtain the engraving plate, and preparing the laser engraving flexible printing plate;

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

10. The method of manufacturing a laser engraved flexographic printing plate according to claim 8, wherein the nanomaterial is one or a combination of more of nanosilica, nanosilica and nanosilica.

11. The method of manufacturing a laser engraved flexographic printing plate according to claim 8, wherein the crosslinking agent is an ammonium salt compound.

12. The method of manufacturing a laser engraved flexographic printing plate according to claim 8, wherein the composition of the adhesive layer comprises:

nitrile rubber 6250105-120

10-35% of white carbon black

Coupling agent kh-5500.5-1

Coupling agent SI-690.5-1

Plasticizer TP-90B5-7

Zinc oxide 3-5

Antioxidant 22460.5-1

Stearic acid 1-1.5

0.5 to 1 percent of sulfur powder

Adhesive AB-300.5-1

Accelerator TT0.8-1

Accelerator CBS0.5-1.