An oxygen barrier layer and a flexographic printing plate with built-in flat-top dots comprising the same

Abstract

The present application is an oxygen barrier layer and a flexographic printing plate with built-in flat top dots. The main component of the oxygen barrier layer is polyvinyl substance, which has the ability of cross-linking polymerization. Under sufficient UV exposure, the cross-linking polymerization of the oxygen barrier layer causes difficulties in removing the oxygen barrier layer during the plate processing, often forming residues in the solid part of the plate material, which cannot be cleaned. The addition of a polymerization inhibitor in the oxygen barrier layer can effectively prevent the formation of residues. The solid part of the plate made by the present application will not form residues under UVA lamp or LED lamp.

Description

TECHNICAL FIELD

[0001] The present application relates to a built-in flat-top dot flexographic printing plate, in particular to an oxygen barrier layer and a built-in flat-top dot flexographic printing plate comprising the same. The present application belongs to the strategic emerging industry directory 3 new material industry 3.1 new functional material industry key direction 3.19 ecological environment material sub-direction green printing material. BACKGROUND

[0002] The flexographic flat-top dot technology has been developed for a long time, and the suppliers of printing plates and the manufacturers of equipment have put forward their own technical solutions. By analyzing these technologies, it is not difficult to find that the existing technologies are all around shielding oxygen or reducing the influence of oxygen on the polymerization of resin in the process of flexographic plate making to realize flat-top dot.

[0003] In the early stage, the influence of oxygen on elastomers was mainly isolated by external equipment.

[0004] Dupont DigiFlow technology uses nitrogen gas filled into the inside of the exposure machine to isolate oxygen. The exposure machine (such as DigiFlow2000EC) is equipped with oxygen concentration detection, UV energy detection and temperature control device to realize accurate control of the exposure process. Nitrogen is the main consumable in this process, and nitrogen cylinder or nitrogen generator is the necessary investment outside the conventional flexographic plate making process. The advantage of this technology is that it does not limit the type of plate material used by the user, and is compatible with all laser plate materials based on black film system, and the comprehensive cost of nitrogen is also very low, but the customer needs to purchase new exposure equipment.

[0005] Kodak NX technology and MDM LUX technology isolate oxygen by laminating film on the surface of the plate material by film laminating machine, so the user must use the special film or imaging material provided by the plate material supplier. Among them, the technology of MDM is an open technology, and the user can use any plate material with black film, so only one laminating machine and the corresponding film need to be purchased to use the original equipment to make flat-top dot. However, unlike the plate making system using black film, Kodak's technology requires the user to use Kodak's NXH plate material, NX thermal imaging film and special laser engraving machine. However, the film laminating technology is sensitive to dust in the environment, and it will also occupy the edge material of the plate material, causing a certain waste.

[0006] The technical route of Fujifilm and Esko is to use high-energy LED UV lamp tubes for exposure during the main exposure stage, and to use the rapidly formed polymerization layer to reduce the influence of oxygen on the process. Esko's technology is called Inline UV technology, which means that high-energy LED UV lamp tubes are built into the traditional laser engraving machine CDI. Compared with the first generation of online UV exposure equipment, the latest Inline UV2 technology with full HD function needs to be exposed after the plate engraving is completed; Fujifilm has built-in LED UV light source in the traditional exposure machine, named NExT technology. The technical route of the two is similar. Although the LED UV lamp tube built into the CDI will reduce the utilization rate of the CDI, if the user purchases the online back exposure unit of Esko, the main exposure equipment is not needed, which helps printing enterprises to improve the process automation level and reduce labor. Fujifilm's exposure machine with built-in LED UV light source solves the problem of CDI time occupation in the main exposure process of InLine UV technology, and adopts the technology of combining LED UV and traditional UV light sources. Users can choose to use LED UV light source alone for exposure, or use LED UV light source and traditional UV light source for mixed exposure, providing users with production convenience and flexibility. Although LED UV light source has an inherent advantage in stable output of UV light source, the problem of too long exposure time and too high equipment cost of using LED UV light source alone is also a defect. The technology of the two companies is completely open technology, which can use laser plates based on black film system, but if you choose LED UV exposure technology, you need to upgrade or purchase additional exposure equipment.

[0007] At present, various companies mainly set an oxygen barrier layer on the plate or improve the photoinitiating efficiency of the plate to achieve the purpose of net point flat top.

[0008] The typical patent of setting an oxygen barrier layer is Fujifilm's CN105745578B, which is composed of water-washable polyvinyl alcohol and other components. CN107969149A, 0.3-5μm oxygen barrier layer, composed of polyvinyl acetal and alkaline adhesive components (oligomeric or polymeric polyvinylamine and polyethyleneimine).

[0009] In actual use, the polyvinyl alcohol component under ultraviolet exposure will form a cross-linked body under the action of the photoinitiator in the photosensitive elastomer once the light intensity reaches a certain level, which is difficult to dissolve and wash off in the plate washing liquid, especially tetrachloroethylene n-butanol plate washing liquid. In the large solid part of the plate, it becomes a residue and cannot be removed.

[0010] Improving the photoinitiation efficiency of the plate material is to produce more free radicals in unit time during the exposure process through a better ultraviolet initiator or initiation system, and to form cross-linking on the surface of the plate material before oxygen quenches them, thereby preventing oxygen from penetrating into the elastomer; or adding more sensitive and cross-linkable monomers to the elastomer, and adding 0.05%-0.2% of butyl hydroxytoluene by weight in the photopolymerizable elastomer layer in the patent CN201680048472.1 of Meidimei to obtain a flat top screen dot. This method is undoubtedly harmful to the light aging resistance of the plate material. The plate material is often deteriorated during the secondary on-press printing process and cannot be printed. SUMMARY

[0011] To solve the above problems, the present application provides an oxygen barrier layer and a built-in flat top screen dot flexible plate containing the same. By adding a polymerization inhibitor to the oxygen barrier layer containing a polyethylene-based substance, the polymerization problem caused by the initiation of the initiator in the photopolymerizable elastomer under ultraviolet exposure is effectively solved. Thus, the problem of residual material formed in the solid part of the plate material during the plate washing process due to the polymerization of the material in the oxygen barrier layer, and the problem of uneven ink on the printing plate caused thereby, are solved.

[0012] The purpose of the present application is achieved in the following manner: an oxygen barrier layer, the raw materials of which include an oxygen barrier agent, an adhesive and a coating aid, the oxygen barrier agent and the adhesive contain a polyethylene-based substance, and the oxygen barrier layer contains a polymerization inhibitor.

[0013] The content of the polymerization inhibitor is 0.1%-5% of the mass of the polyethylene-based substance.

[0014] The oxygen barrier agent is polyvinylpyrrolidone, the adhesive is polyvinylamine, the oxygen barrier layer contains 50-80% of polyvinylpyrrolidone by mass percentage, the K value of the polyvinylpyrrolidone is 100-150, the mass of the polyvinylamine is 10%-50% of the mass of the polyvinylpyrrolidone, the content of the polymerization inhibitor is 0.1%-5% of the mass of the polyvinylpyrrolidone, and the coating aid includes at least one of a surfactant, a leveling agent or a thickening agent.

[0015] The polymerization inhibitor includes at least one of a phenolic polymerization inhibitor, a quinone polymerization inhibitor, an aromatic hydrocarbon nitro compound polymerization inhibitor or an inorganic compound polymerization inhibitor.

[0016] The phenolic polymerization inhibitor is hydroquinone, resorcinol, catechol or tert-butyl catechol, the quinone polymerization inhibitor is p-benzoquinone, methyl chloroquinone or tetrachloroquinone, and the inorganic compound polymerization inhibitor is sodium sulfate, ferric chloride, sodium sulfide or ammonium thiocyanate.

[0017] A built-in flat top screen dot flexible plate, from top to bottom, includes a protective layer, a laser ablation mask layer, an oxygen barrier layer, a photopolymerizable elastomer and a support body, and the oxygen barrier layer is the above-mentioned oxygen barrier layer.

[0018] In comparison with the prior art, the flexographic plate with built-in flat dots is provided with an oxygen barrier layer on the photosensitive elastomer, which blocks the quenching of the free radicals generated in the photosensitive elastomer by oxygen in the air during ultraviolet exposure, thereby improving the crosslinking efficiency and depth.

[0019] The main component of the oxygen barrier layer for blocking the penetration of oxygen is a polyvinyl substance, which also has the ability of crosslinking polymerization. Under sufficient ultraviolet exposure, the crosslinking polymerization of the polyvinyl substance causes difficulties in removing the oxygen barrier layer during the plate processing, and often forms residues in the solid part of the plate material, which cannot be cleaned completely. The addition of the polymerization inhibitor in the oxygen barrier layer can effectively prevent the formation of residues. The solid part of the plate produced by the present application will not form residues under the UVA lamp tube or LED lamp bead. DETAILED DESCRIPTION

[0020] The present application will be described in detail below with reference to specific embodiments. It is necessary to point out that the embodiments are only used to further illustrate the present application and cannot be understood as limiting the protection scope of the present application. Those skilled in the art can make some non-essential improvements and adjustments according to the content of the present application.

[0021] An oxygen barrier layer, the raw materials of which include an oxygen barrier agent, an adhesive and a coating aid, the oxygen barrier agent and the adhesive contain a polyvinyl substance, characterized in that the oxygen barrier layer further contains a polymerization inhibitor.

[0022] The content of the polymerization inhibitor is 0.1%-5% of the mass of the polyvinyl substance.

[0023] The oxygen barrier agent is polyvinylpyrrolidone, the adhesive is polyvinylamine, the dry mass of the oxygen barrier layer is calculated according to the percentage of the mass, the content of polyvinylpyrrolidone is 50-80%, the K value of polyvinylpyrrolidone is 100-150, the mass of polyvinylamine is 10%-50% of the mass of polyvinylpyrrolidone, the content of the polymerization inhibitor is 0.1%-5% of the mass of polyvinylpyrrolidone, and the coating aid includes at least one of a surfactant, a leveling agent or a thickening agent. Polyvinylamine is an excellent adhesive, which bonds the photosensitive elastomer layer and the laser ablation mask layer into one body. Moreover, the adhesion of polyvinylamine is not affected by carbon dioxide in the air, and the adhesion will not decay.

[0024] The polymerization inhibitor includes at least one of a phenolic polymerization inhibitor, a quinone polymerization inhibitor, an aromatic hydrocarbon nitro compound polymerization inhibitor or an inorganic compound polymerization inhibitor.

[0025] The phenolic polymerization inhibitor is hydroquinone, resorcinol, catechol or tert-butyl catechol, the quinone polymerization inhibitor is p-benzoquinone, methyl chloroquinone or tetrachloroquinone, and the inorganic compound polymerization inhibitor is sodium sulfate, ferric chloride, sodium sulfide or ammonium thiocyanate.

[0026] A flexographic printing form comprising from top to bottom a protective layer, a laser ablatable mask layer, an oxygen barrier layer, a photopolymer layer, a support, the oxygen barrier layer being the oxygen barrier layer as described above.

[0027] The laser ablatable mask layer, the oxygen barrier layer, the photopolymer layer can be dissolved or dispersed in halogenated hydrocarbons, alcohols, amines and other solvents, i.e. in popular flexographic washout solutions on the market, such as Minchen washout solution, n-butanol and tetrachloroethylene washout solution.

[0028] The support

[0029] The support is a dimensionally stable carrier. Usually a dimensionally stable carrier of 50-300 μm thickness is used, which is made of steel, aluminium, an alloy or a plastic, such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate or polycarbonate. Especially suitable is a PET film of 100-200 μm thickness. In a normal flexographic printing form, a PET film of 175 μm thickness is used for a printing form of 1.14 mm thickness and below, and a PET film of 125 μm thickness is used for a flexographic printing form of a greater thickness.

[0030] The carrier can be optionally subjected to a conventional adhesion treatment, such as corona treatment, chemical etching, physical bonding and the like.

[0031] Between the support and the photopolymer layer, other layers can be present, such as an adhesive layer or a layer that enhances the elasticity.

[0032] The photopolymer layer

[0033] The photopolymer layer generally comprises at least one elastomeric binder, an ethylenically unsaturated monomer and a photoinitiator system. Other ingredients can also be present, such as plasticizers, dyes, UV absorbers and the like. The photopolymer layer is also called a photopolymerizable relief-forming layer.

[0034] The elastomeric binder is known to the person skilled in the art, such as styrene-diene block copolymers, natural rubber, polybutadiene, polyisoprene, styrene-butadiene rubber, nitrile rubber, butyl rubber, styrene-isoprene rubber, styrene-butadiene-isoprene rubber, polynorbornene rubber or ethylene-propylene-diene rubber. Preference is given to a binder that is soluble in non-polar hydrocarbon solvents and in alcohols with moderate polarity.

[0035] The elastomer preferably comprises a thermoplastic elastomeric block copolymer of an alkenyl aromatic compound and a 1, 3-diene, the preferred elastomeric binder being a triblock copolymer of the A-B-A type or a radial block copolymer of the (AB)n type, wherein A is styrene and B is diene, as well as statistical and random copolymers of styrene and diene. The total amount of elastomeric binder is preferably in the range from 45 to 75% by weight;

[0036] Monomers containing olefinically unsaturated double bonds and being polymerizable, usually 3 to 15 mass-%.

[0037] At least one photoinitiator or photoinitiator system, preferably 3 to 6 wt.-%; plasticizer is modified and unmodified natural oils and natural resins, in optional amounts of 0 to 40 mass-%. In addition, surface-active substances, such as hydrophobic waxes or siliconizing or perfluorinated compounds, can also be contained, as described in us 8,114,566. During drying of the flexographic printing form, these substances migrate from the relief layer to the surface, repel the printing ink and reduce the fouling of fine dots during printing and thus the frequency of cleaning of the printing form.

[0038] The thickness of the relief-forming layer is usually 0.1 to 7 mm, preferably 0.5 to 4 mm, and more preferably 0.7 to 2.5 mm.

[0039] Oxygen barrier layer

[0040] The thickness of the oxygen barrier layer is 0.5 to 5 μηη.

[0041] The oxygen barrier layer is arranged between the photopolymer layer and the laser-ablatable mask layer / laser-ablatable black film, and is capable of bonding the photopolymer layer and the laser-ablatable mask layer together. When the protective film is removed, the laser-ablatable mask layer black film can be perfectly separated from the protective film and completely cover the surface of the photopolymer. At the same time, when the laser-ablatable mask layer, such as the black film, is subjected to laser ablation imaging, the laser ablation does not damage the oxygen barrier layer, and the oxygen barrier layer remains intact on the photopolymer after the black film is ablated.

[0042] The oxygen permeability of the oxygen barrier layer is usually less than 1000, preferably less than 500 (cm 3 × 100 μηι) / (m 2 × d x bar). In principle, any flexible elastic adhesive having an oxygen permeability below the agreed maximum value can be used for the oxygen barrier layer (C), while meeting other essential requirements, such as transparency to UVA light and solubility or dispersibility in commercially available flexographic processing media.

[0043] Flexible adhesives having an oxygen barrier effect, such as polyvinylpyrrolidone. The K value of polyvinylpyrrolidone is related to its flexibility, and a K value above 100 is selected to ensure that the oxygen barrier layer has sufficient flexibility. This feature is particularly valuable in low temperatures in winter. Polyvinylpyrrolidone coatings with low K values are prone to brittle fracture.

[0044] The simple polyvinylpyrrolidone is difficult to perfectly bond the laser-ablatable mask layer / laser-ablatable black film and the photosensitive elastomer together. Therefore, a basic adhesive component is needed to increase the bonding, which is the low or high basic adhesive component, i.e. the amine group water-soluble resin, such as polyvinylamine. Other adhesives, such as polyethylene imine, are good enough, but the bonding gradually decays over time, which even affects the integrity of the laser-ablatable mask layer / laser-ablatable black film when the protective sheet base is removed using the plate material. The polyvinylamine does not have this defect.

[0045] The thickness of the oxygen barrier layer is particularly preferably 1 μm to 2 μm. A thicker oxygen barrier layer is more beneficial to the perfectness of the oxygen barrier, but the dot size is enlarged, which becomes a problem of the plate material, and a thicker oxygen barrier layer is prone to breakage at low temperature. A thinner oxygen barrier layer is not good enough to block oxygen, and the crosslinking of small dots is partially affected by oxygen, which cannot be well restored. Since the dissolution and swelling of the oxygen barrier layer in the plate washing solution cannot be too much, the thinner the better under the condition of ensuring the effect of the oxygen barrier.

[0046] Laser-ablatable mask layer

[0047] The laser-ablatable mask layer, also called laser-ablatable black film, has a thickness of 0.5-5 μm. It at least comprises an adhesive and a material capable of blocking ultraviolet rays and absorbing infrared rays. The adhesive of the laser-ablatable mask layer (D) is selected from polyamide, polyvinylpyrrolidone (PVP), nitrocellulose and polyvinyl acetal, and polyamide is preferred. The material capable of blocking ultraviolet rays and absorbing infrared rays is selected from carbon black, graphite, carbon nanoparticles and carbon nanotubes, and carbon nanoparticles are preferred.

[0048] The film layer can absorb infrared laser and be ablated by laser, such as the 830 nm and 1064 nm laser imagers on the market, which can be ablated by laser to become a mask.

[0049] On the one hand, the film layer can absorb infrared laser and burn, and on the other hand, the film layer also needs to have sufficient blocking effect on ultraviolet rays, so that the photosensitive elastomer covered by the black film will not crosslink and polymerize under UVA exposure during the plate making process.

[0050] The film layer also needs to be able to dissolve or disperse in the plate washing solution available on the market.

[0051] The component capable of absorbing infrared rays and being ablated by infrared rays in the laser-ablatable mask layer is carbon black, including various forms of carbon black, such as carbon black, graphite, carbon nanoparticles and carbon nanotubes. Among them, carbon nanoparticles are the most preferred.

[0052] A very suitable adhesive for the mask layer is a flexible elastomeric adhesive, such as ethylene-vinyl acetate, flexible elastomeric polyamide, flexible elastomeric polyurethane, nitrocellulose, polyvinyl acetal such as poly(vinyl butyral-vinyl alcohol) copolymer (Butvar®, Mowital®) or poly(vinyl butyral-vinyl acetal-vinyl alcohol) copolymer (Pioloform®). Of course, other flexible elastomeric materials can also be used as adhesive, such as partially hydrolysed polyvinyl acetate. A preferred adhesive for the mask layer is the flexible elastomeric polyamide Technomelt® PA6900.

[0053] The amount of light absorbing material is generally such that the optical density of the layer for UVA radiation is 1-5. The UVA radiation range includes light having a wavelength of 300-400 nm. The optical density is the logarithmic factor of the light permeability of the layer in this wavelength range. Thus, when measuring the optical density, the value determined is not a single value of the light permeability at a specific wavelength, but an average value of the light permeability in the specified wavelength range. The optical density is generally measured using a commercially available densitometer (for example from X-Rite), in which the wavelength range is chosen before the measurement. For the present application, all quoted optical density measurements are based on the UVA range, i.e. the range of 300-400 nm.

[0054] The optical density of the preferred mask layer is 2-5. A high optical density ensures that the area of the light-sensitive elastomer covered by the mask does not polymerise during exposure to UVA light. Suitable light absorbing materials include, inter alia, carbon black, graphite, carbon black nanoparticles or carbon nanotubes. These materials absorb very well in the near-IR range and are therefore both laser-ablatable materials and UV-blocking materials. The amount of such material used is in the range of 10% by weight to 60% by weight, preferably in the range of 20% to 40% of the entire mask layer. The weight of the mask layer is in the range of 2-5 g / m 2 , preferably 2-4 g / m 2 , when in this range, the ablation energy is approximately 3.0-4.5 J / cm 2 , which is well suited to the laser ablation imaging machines on the market for flexographic plates and enables the laser ablation imaging machine to work in a normal state and with suitable efficiency.

[0055] Protective layer

[0056] The protective layer is a removable protective film. Its purpose is to protect the flexographic plate. It is removed before laser ablation imaging. The material of the removable outer film can be a PET film. The thickness is in the range of 80-150 μm, preferably 100-130 μm, and the average roughness value (Ra) is preferably in the range of 0.02-0.5 μm. The film material can be transparent or semi-opaque, in general, the film material preferably has a certain haze, which facilitates the distinction between the two sides of the plate material.

[0057] Production of a flexographic printing plate according to the invention

[0058] The flexographic printing plate according to the invention is produced in a known manner by melting the components of the photopolymer layer in an extruder, mixing them and discharging the melt of the photopolymer layer material through a slot die into the nip of a calender. Running on one calender roll is the support, which is coated with further layers, such as an adhesive layer, and running via the other calender roll is the protective film, which comprises the oxygen barrier layer, the laser ablatable mask layer and the protective film. By calendering the support, the photopolymer and the protective film with the oxygen barrier layer and the laser ablatable mask layer are combined.

[0059] In the production of the protective film assembly, the laser ablatable mask layer is first applied to the protective film. This application procedure can be carried out from solution, from melt or by spraying. Subsequently, the oxygen barrier layer is applied over the laser ablatable mask layer. Before applying the individual layers, it can be necessary to treat the surface of the support PET sheet to be coated by means of corona or the like in order to achieve a greater spreading ability. It must be stated that the effect of the corona pretreatment generally decreases with the storage time of the printing plate and cannot achieve a permanently satisfactory adhesion.

[0060] Alternatively, the individual layers can also be applied separately to different films, which are then laminated together. For example, the mask layer and the oxygen barrier layer can also be applied each to a separate film. In this case, the mask layer is applied to the protective film and the oxygen barrier layer is applied to a temporary auxiliary film. After the application has been carried out, the two films are laminated to one another by lamination and the temporary auxiliary film is removed.

[0061] The techniques for the application are known to the person skilled in the art. The thickness of the layers to be applied can be adjusted in a known manner by releasing the application liquid or by changing the application parameters, such as the knife gap or the application speed or the feed speed. In order to improve the quality of the coating, it can be necessary to add surface-active substances or flow-control auxiliaries, such as levelling agents or thickeners, to the application solution.

[0062] The coated protective film is wound up and passed through one of the calender rolls during the subsequent extrusion and in this way is firmly bound to the photopolymer as a whole.

[0063] Alternatively, a layer-by-layer lamination can also be used in several steps. For example, the oxygen barrier layer, which is contained on a temporary auxiliary film, can be passed through the calender roll and combined with the photopolymer layer. The auxiliary film is then removed. The laser ablatable mask layer is then laminated to the photopolymer layer with the oxygen barrier layer in a second lamination step to produce the printing plate.

[0064] Process for the production of a flexographic printing plate according to the invention

[0065] The process for producing a printing plate according to the invention comprises the following method steps 1 to 7:

[0066] 1. Back exposure of the plate material to form a suitable base. This step can also be performed after step 4.

[0067] 2. Removal of the protective film. Only the protective film is removed, and the laser ablatable mask layer and the underlying oxygen barrier layer remain intact on the photosensitive elastomer.

[0068] 3. Imaging of the laser ablatable mask layer with an IR laser. Such a laser imaging machine is also called a CDI, and there are currently two machines on the market, one with a wavelength of 1064 nm and the other with a wavelength of 830 nm.

[0069] 4. Exposure of the photosensitive elastomer to UVA light through the mask layer. This can be a conventional UVA lamp or the latest UV LED lamp bead.

[0070] 5. Removal of the residual laser ablatable mask layer, the oxygen barrier layer, and the unpolymerized portion of the photosensitive elastomer using a flexographic washout solution. This can be a solution of tetrachloroethylene and n-butanol mixed at a volume ratio of 3:1, or various environmentally friendly washout solutions commonly found on the market.

[0071] 6. Sufficient drying of the resulting flexographic printing plate.

[0072] 7. Post-exposure under UVA and de-adhesion under UVC, or omitting this step.

[0073] After the above plate making process, the plate material becomes a printable flexographic plate. This plate making process is exactly the same as that of a conventional digital flexographic plate.

[0074] When using the flexographic plate material of the present application, there is no need for expensive and inconvenient exposure conditions such as nitrogen charging, nor is there a need to laminate a film over the imaged laser ablatable mask layer, nor is there a need to laminate the imaged film onto the photosensitive elastomer using a lamination device.

[0075] Alternatively, the flexographic plate material of the present application can also be thermally developed. In this case, the flexographic plate material is mounted on a drum and heated from the surface until melting occurs. Then a fabric strip is pressed against the flexographic plate material to remove the unexposed areas of the photosensitive elastomer, the oxygen barrier layer, and the residual portion of the laser ablatable mask layer. This operation is repeated multiple times until the desired relief height is achieved.

[0076] Example 1

[0077] This patent is based on digital flexographic plates and is achieved by adding an oxygen barrier layer. The technology related to digital flexographic plates is omitted.

[0078] In the embodiment of the oxygen barrier layer, the following components are used, with the unit being parts by mass:

[0079] Polyvinylpyrrolidone K100 100

[0080] Polyvinylamine, 15 million molecular weight 20

[0081] Polymerization inhibitor (phenolic compound), hydroquinone 2

[0082] Sodium dodecylsulfonate 5

[0083] Preparation of oxygen barrier layer

[0084] Polyvinylpyrrolidone was prepared into an 8% aqueous solution, under stirring (300-500 rpm), polyvinylamine (previously prepared into a 5% aqueous solution) was slowly added, then a 1% aqueous solution of hydroquinone (freshly prepared) was added, and finally the surfactant was added. After proper stirring, the coating liquid was obtained.

[0085] Preparation of plate material

[0086] The coating liquid of the oxygen barrier layer was applied to the photosensitive elastomer of Huaguang DR170LS by a 40# wire bar, and then the black film with the protective film was overlaid on the oxygen barrier layer; or the oxygen barrier layer was applied to the black film in the same way, and then overlaid on the photosensitive elastomer of Huaguang DR170LS. Heating was carried out at a temperature of 100-120°C for 5 minutes. After cooling to room temperature, the plate material was prepared.

[0087] Plate making method

[0088] Then, plate making was carried out like a common digitalized flexible resin plate. For example, after back exposure, the protective film on the black film was removed, laser imaging was carried out on the ESKO CDI, exposure was carried out on the Kemaotuo ordinary UVA lamp tube for 15 minutes (LED lamp bead main exposure results are better), and plate washing was carried out on the Kemaotuo ordinary online plate washing machine at a washing speed of 160 mm / min (or on the platform plate washing machine), using the commercially available Minchen environmentally friendly plate washing liquid (or tetrachloroethylene plate washing liquid, the volume ratio of tetrachloroethylene to n-butanol is 3:1). After plate baking for 1.5 hours, post-exposure was carried out for 5 minutes and adhesion removal was carried out for 5 minutes.

[0089] Plate material test:

[0090] 150lpi, without adding a correction curve, the 1% dot of the dot tester can be restored to 1%. The eye observation shows that the solid part is smooth and clean. Under a microscope, no foreign matter is attached.

[0091] The following other examples have the same preparation method and test method except that the amount of the raw material components of the oxygen barrier layer is changed.

[0092] Example 2

[0093] This patent is realized on the basis of digital flexographic plate by adding oxygen barrier layer. The technology of digital flexographic plate is not mentioned.

[0094] In the embodiment of oxygen barrier layer, the following components are used:

[0095] Polyvinylpyrrolidone K120 100

[0096] Polyvinylamine, molecular weight 150,000 20

[0097] Polymerization inhibitor (phenolic compound), hydroquinone 2

[0098] Sodium dodecyl sulfonate 5

[0099] Preparation of oxygen barrier layer

[0100] Polyvinylpyrrolidone is prepared into an 8% aqueous solution. Under stirring (300-500 rpm), polyvinylamine (previously prepared into a 5% aqueous solution) is slowly added, then a 1% aqueous solution of hydroquinone (freshly prepared) is added, and finally sodium dodecyl sulfonate is added. After appropriate stirring, a coating liquid is obtained.

[0101] Preparation of plate material

[0102] The coating liquid of the oxygen barrier layer is coated on the photosensitive elastomer of Huaguang DR170LS with the protective film and black film removed by using a 40# wire bar, and then the black film with the protective film removed is overlaid on the oxygen barrier layer; or the oxygen barrier layer is coated on the black film in the same way, and then overlaid on the photosensitive elastomer of Huaguang DR170LS. Heating is carried out at a temperature of 100-120°C for 5 minutes. After cooling to room temperature, the plate material is prepared.

[0103] Plate making method

[0104] Then, plate making is carried out like ordinary digital flexographic resin plate. For example, after back exposure, the protective film on the black film is removed, laser imaging is carried out on the ESKO CDI, exposure is carried out on the Kema exposure machine ordinary UVA lamp tube for 15 minutes (LED lamp bead main exposure result is better), and plate washing is carried out on the Kema ordinary online plate washing machine at a plate washing speed of 160 mm / min (or on the platform plate washing machine), using the commercially available sensitive morning environmentally friendly plate washing liquid (or tetrachloroethylene plate washing liquid, the volume ratio of tetrachloroethylene to n-butanol is 3:1). After plate baking for 1.5 hours, post-exposure is carried out for 5 minutes and adhesion removal is carried out for 5 minutes.

[0105] Test the plate material:

[0106] At 150 lpi, 1% dot can be restored to 1% without adding a correction curve, and the solid part is smooth and clean.

[0107] Example 3

[0108] This patent is achieved by adding an oxygen barrier layer to the digital flexible plate. The technical details of the digital flexible plate involved are omitted.

[0109] In the embodiments of the oxygen barrier layer, the following components are used:

[0110] Polyvinylpyrrolidone K150 100

[0111] Polyvinylamine, molecular weight 152,000

[0112] Polymerization inhibitor (phenolic compound), hydroquinone 2

[0113] Sodium dodecyl sulfonate 5

[0114] Preparation of oxygen barrier layer

[0115] Prepare an 8% aqueous solution of polyvinylpyrrolidone. While stirring (300-500 rpm), slowly add polyvinylamine (prepared as a 5% aqueous solution), then add a 1% aqueous solution of hydroquinone (prepared fresh for use), and finally add sodium dodecyl sulfonate. After appropriate stirring, the coating solution is obtained.

[0116] Preparation of printing plates

[0117] The coating solution for the oxygen barrier layer is applied using a No. 40 wire rod to the photosensitive elastomer of the Huaguang DR170LS after the protective film and black film have been removed. Then, the black film with the removed protective film is pressed onto the oxygen barrier layer; alternatively, the oxygen barrier layer is applied onto the black film using the same method, and then pressed onto the Huaguang DR170LS photosensitive elastomer. The film is heated at 100-120°C for five minutes. After cooling to room temperature, the printing plate is formed.

[0118] Plate making method

[0119] Then, plate making is performed as with ordinary digital flexographic resin plates. For example, after back exposure, the protective film on the black film is removed, laser imaging is performed on an ESKO CDI, and exposure is performed for 15 minutes on a standard UVA lamp in a Ke Mao exposure machine (LED lamp beads provide better main exposure results). The plate is then washed at a washing speed of 160 mm / min on a standard inline plate washer in Ke Mao (or on a platform plate washer) using commercially available Min Chen environmentally friendly plate washer solution (or tetrachloroethylene plate washer solution, with a tetrachloroethylene to n-butanol volume ratio of 3:1). After baking the plate for 1.5 hours, a post-exposure of 5 minutes and a de-adhesion of 5 minutes are performed.

[0120] Test the printing plate:

[0121] At 150 lpi, without adding a correction curve, 1% of dots can be reproduced as 0.8%, and the solid areas are smooth and clean.

[0122] Example 4

[0123] The present patent is realized by adding an oxygen barrier function layer on the basis of digital flexography. The technology related to digital flexography is omitted.

[0124] In the embodiment of the oxygen barrier layer, the following components are used:

[0125] Polyvinylpyrrolidone K120 100

[0126] Polyvinylamine, molecular weight 100,000 20

[0127] Polymerization inhibitor (phenolic compound), hydroquinone 2

[0128] Sodium dodecylsulfate 5.

[0129] Preparation of the oxygen barrier layer

[0130] Polyvinylpyrrolidone is prepared into an 8% aqueous solution. Under stirring (300-500 rpm), polyvinylamine (previously prepared into a 5% aqueous solution) is slowly added, then a 1% aqueous solution of hydroquinone (freshly prepared) is added, and finally sodium dodecylsulfate is added. After appropriate stirring, a coating liquid is obtained.

[0131] Preparation of the plate material

[0132] The coating liquid of the oxygen barrier layer is coated on the photosensitive elastomer of Huaguang DR170LS with the protective film and black film removed by using a 40# wire bar, and then the black film with the protective film removed is overlaid on the oxygen barrier layer; or the oxygen barrier layer is coated on the black film in the same way, and then overlaid on the photosensitive elastomer of Huaguang DR170LS. Heating is carried out at a temperature of 100-120°C for 5 minutes. After cooling to room temperature, the plate material is prepared.

[0133] Plate making method

[0134] Then, plate making is carried out like ordinary digital flexographic resin plates. For example, after back exposure, the protective film on the black film is removed, laser imaging is carried out on the ESKO CDI, exposure is carried out on the Kemaotuo ordinary UVA lamp tube for 15 minutes (LED lamp bead main exposure results are better), and plate washing is carried out on the Kemaotuo ordinary online plate washing machine at a plate washing speed of 160 mm / min (or on the platform plate washing machine), using the commercially available sensitive morning environmentally friendly plate washing liquid (or tetrachloroethylene plate washing liquid, the volume ratio of tetrachloroethylene to n-butanol is 3:1). After plate baking for 1.5 hours, post-exposure is carried out for 5 minutes and adhesion removal is carried out for 5 minutes.

[0135] Test the plate material:

[0136] At 150 lpi, 1% dot can be restored to 0.8% without adding a correction curve, and the solid part is smooth and clean.

[0137] Example 5

[0138] The present patent is realized by adding an oxygen barrier function layer on the basis of digital flexography. The technology related to digital flexography is omitted.

[0139] In the embodiment of the oxygen barrier layer, the following components are used:

[0140] Polyvinylpyrrolidone K120 100

[0141] Polyvinylamine, molecular weight 200,000 20

[0142] Polymerization inhibitor (phenolic compound), hydroquinone 2

[0143] Sodium dodecyl sulfonate 5

[0144] Preparation of the oxygen barrier layer

[0145] Polyvinylpyrrolidone is prepared into an 8% aqueous solution. Under stirring (300-500 rpm), polyvinylamine (previously prepared into a 5% aqueous solution) is slowly added, then a 1% aqueous solution of hydroquinone (freshly prepared) is added, and finally sodium dodecyl sulfonate is added. After appropriate stirring, a coating liquid is obtained.

[0146] Preparation of the plate material

[0147] The coating liquid of the oxygen barrier layer is applied to the photosensitive elastomer of Huaguang DR170LS with the protective film and black film removed by a 40# wire bar, and then the black film with the protective film removed is overlaid on the oxygen barrier layer; or the oxygen barrier layer is applied to the black film in the same way, and then overlaid on the photosensitive elastomer of Huaguang DR170LS. Heating is carried out at a temperature of 100-120°C for five minutes. After cooling to room temperature, the plate material is prepared.

[0148] Plate making method

[0149] Then, plate making is carried out like ordinary digital flexographic resin plates. For example, after back exposure, the protective film on the black film is removed, laser imaging is carried out on the ESKO CDI, exposure is carried out on the Kema exposure machine with ordinary UVA lamp tubes for 15 minutes (LED lamp beads are better for main exposure), and plate washing is carried out on the Kema ordinary online plate washing machine at a washing speed of 160 mm / min (or on the platform plate washing machine), using commercially available sensitive environmental washing liquid (or tetrachloroethylene washing liquid, the volume ratio of tetrachloroethylene to n-butanol is 3:1). After plate baking for 1.5 hours, post-exposure is carried out for 5 minutes and adhesion removal is carried out for 5 minutes.

[0150] Test the plate material:

[0151] At 150 lpi, 1% dots can be reproduced without adding a correction curve, and the solid part is smooth and clean.

[0152] Example 6

[0153] This patent is achieved by adding an oxygen barrier layer to the digital flexible plate. The technical details of the digital flexible plate involved are omitted.

[0154] In the embodiments of the oxygen barrier layer, the following components are used:

[0155] Polyvinylpyrrolidone K120 100

[0156] Polyvinylamine, molecular weight 200,000

[0157] Polymerization inhibitor (quinone compound), tetrachlorobenzoquinone 2

[0158] Sodium dodecyl sulfonate 5

[0159] Preparation of oxygen barrier layer

[0160] Prepare an 8% aqueous solution of polyvinylpyrrolidone. While stirring (300-500 rpm), slowly add polyvinylamine (prepared as a 5% aqueous solution), then add a 1% aqueous solution of hydroquinone (prepared fresh for use), and finally add sodium dodecyl sulfonate. After appropriate stirring, the coating solution is obtained.

[0161] Preparation of printing plates

[0162] The coating solution for the oxygen barrier layer is applied using a No. 40 wire rod to the photosensitive elastomer of the Huaguang DR170LS after the protective film and black film have been removed. Then, the black film with the removed protective film is pressed onto the oxygen barrier layer; alternatively, the oxygen barrier layer is applied onto the black film using the same method, and then pressed onto the Huaguang DR170LS photosensitive elastomer. The film is heated at 100-120°C for five minutes. After cooling to room temperature, the printing plate is formed.

[0163] Plate making method

[0164] Then, plate making is performed as with ordinary digital flexographic resin plates. For example, after back exposure, the protective film on the black film is removed, laser imaging is performed on an ESKO CDI, and exposure is performed for 15 minutes on a standard UVA lamp in a Ke Mao exposure machine (LED lamp beads provide better main exposure results). The plate is then washed at a washing speed of 160 mm / min on a standard inline plate washer in Ke Mao (or on a platform plate washer) using commercially available Min Chen environmentally friendly plate washer solution (or tetrachloroethylene plate washer solution, with a tetrachloroethylene to n-butanol volume ratio of 3:1). After baking the plate for 1.5 hours, a post-exposure of 5 minutes and a de-adhesion of 5 minutes are performed.

[0165] Test the printing plate.

[0166] At 150 lpi, without adding a correction curve, 1% of the dots can be reproduced as 0.5%, and the solid areas are smooth and clean.

[0167] Example 7

[0168] This patent is realized on the basis of digital flexographic plate by adding oxygen barrier function layer. The technology of digital flexographic plate is omitted.

[0169] In the embodiment of oxygen barrier layer, the following components are used:

[0170] Polyvinylpyrrolidone K120 100

[0171] Polyvinylamine, molecular weight 200,000 20

[0172] Polymerization inhibitor (aromatic nitro compound), nitrobenzene 2

[0173] Sodium dodecyl sulfonate 5

[0174] Preparation of oxygen barrier layer

[0175] Polyvinylpyrrolidone is prepared into an 8% aqueous solution. Under stirring (300-500 rpm), polyvinylamine (previously prepared into a 5% aqueous solution) is slowly added, then a 1% aqueous solution of hydroquinone (freshly prepared) is added, and finally sodium dodecyl sulfonate is added. After appropriate stirring, a coating liquid is obtained.

[0176] Preparation of plate material

[0177] The coating liquid of the oxygen barrier layer is coated on the photosensitive elastomer of Huaguang DR170LS with the protective film and black film removed by a 40 number wire bar, and then the black film with the protective film removed is overlaid on the oxygen barrier layer; or the oxygen barrier layer is coated on the black film in the same way, and then overlaid on the photosensitive elastomer of Huaguang DR170LS. Heating is carried out at a temperature of 100-120°C for five minutes. After cooling to room temperature, the plate material is prepared.

[0178] Plate making method

[0179] Then, plate making is carried out like ordinary digital flexographic resin plate. For example, after back exposure, the protective film on the black film is removed, laser imaging is carried out on ESKO CDI, exposure is carried out on the exposure machine of KeMao with ordinary UVA lamp tube for 15 minutes (LED lamp bead main exposure result is better), and plate washing is carried out on the ordinary online plate washing machine of KeMao at a plate washing speed of 160 mm / min (or on the platform plate washing machine), using the commercially available environmentally friendly plate washing liquid of Minchen (or tetrachloroethylene plate washing liquid, the volume ratio of tetrachloroethylene to n-butanol is 3:1). After plate baking for 1.5 hours, post exposure is carried out for 5 minutes and adhesion removal is carried out for 5 minutes.

[0180] The plate material is tested.

[0181] At 150 lpi, 1% dot can be restored to 0.3% without correction curve, and the solid part is smooth and clean.

[0182] Example 8

[0183] This patent is realized on the basis of digital flexographic plate by adding oxygen barrier layer. The technology of digital flexographic plate is not mentioned.

[0184] In the embodiment of oxygen barrier layer, the following components are used:

[0185] Polyvinylpyrrolidone K120 100

[0186] Polyvinylamine, molecular weight 200,000 20

[0187] Polymerization inhibitor (inorganic compound), sodium sulfate 1

[0188] Sodium dodecyl sulfonate 5

[0189] Preparation of oxygen barrier layer

[0190] Polyvinylpyrrolidone is prepared into an 8% aqueous solution, under stirring (300-500 rpm), polyvinylamine (previously prepared into a 5% aqueous solution) is slowly added, then a 1% aqueous solution of hydroquinone (freshly prepared) is added, and finally sodium dodecyl sulfonate is added. After appropriate stirring, a coating liquid is obtained.

[0191] Preparation of plate material

[0192] The coating liquid of the oxygen barrier layer is coated on the photosensitive elastomer of Huaguang DR170LS with the protective film and black film removed by a 40 number wire bar, and then the black film with the protective film removed is overlaid on the oxygen barrier layer; or the oxygen barrier layer is coated on the black film in the same way, and then overlaid on the photosensitive elastomer of Huaguang DR170LS. Heat at a temperature of 100-120°C for five minutes. Cool to room temperature to prepare the plate material.

[0193] Plate making method

[0194] Then, plate making is carried out like ordinary digital flexographic resin plate. For example, after back exposure, the protective film on the black film is removed, laser imaging is carried out on ESKO CDI, exposure is carried out on Kemaotuo ordinary UVA lamp tube for 15 minutes (LED lamp bead main exposure result is better), plate washing is carried out on Kemaotuo ordinary online plate washing machine at a washing speed of 160 mm / min (or on a platform plate washing machine), using commercially available sensitive morning environmentally friendly plate washing liquid (or tetrachloroethylene plate washing liquid, the volume ratio of tetrachloroethylene to n-butanol is 3:1). After baking the plate for 1.5 hours, post-exposure for 5 minutes and adhesion removal for 5 minutes.

[0195] Test the plate material:

[0196] At 150 lpi, 2% dot can be restored to 0.5% without correction curve, and the solid part is smooth and clean.

[0197] Example 9

[0198] This patent is realized on the basis of digital flexographic plate by adding oxygen barrier layer. The technology of digital flexographic plate is not mentioned.

[0199] In the embodiment of oxygen barrier layer, the following components are used:

[0200] Polyvinylpyrrolidone K120 80

[0201] Polyvinylamine, molecular weight 200,000 14.9

[0202] Polymerization inhibitor (phenolic compound), hydroquinone 0.1

[0203] Sodium dodecyl sulfonate 5;

[0204] Preparation of oxygen barrier layer

[0205] Polyvinylpyrrolidone is prepared into an 8% aqueous solution, under stirring (300-500 rpm), polyvinylamine (previously prepared into a 5% aqueous solution) is slowly added, then 1% aqueous solution of hydroquinone (freshly prepared) is added, and finally the surfactant is added. After appropriate stirring, the coating liquid is obtained.

[0206] Preparation of plate material

[0207] The coating liquid of the oxygen barrier layer is coated on the photosensitive elastomer of Huaguang DR170LS with the protective film and black film removed by using a 40 number wire bar, and then the black film with the protective film removed is overlaid on the oxygen barrier layer; or the oxygen barrier layer is coated on the black film in the same way, and then overlaid on the photosensitive elastomer of Huaguang DR170LS. Heat at a temperature of 100-120℃ for five minutes. Cool to room temperature to prepare the plate material.

[0208] Plate making method

[0209] Then, plate making is carried out like ordinary digital flexographic resin plate. For example, after back exposure, the protective film on the black film is removed, laser imaging is carried out on ESKO CDI, exposure is carried out on Kemaotuo ordinary UVA lamp tube for 15 minutes (LED lamp bead main exposure result is better), plate washing is carried out on Kemaotuo ordinary online plate washing machine at a washing speed of 160 mm / min (or on a platform plate washing machine), using commercially available sensitive environmental washing liquid (or tetrachloroethylene washing liquid, the volume ratio of tetrachloroethylene to n-butanol is 3:1). After baking the plate for 1.5 hours, post-exposure for 5 minutes and adhesion removal for 5 minutes.

[0210] Test the plate material:

[0211] At 150 lpi, 2% dot can be restored to 1.6% without correction curve, and the solid part is smooth and clean.

[0212] Example 10

[0213] This patent is realized on the basis of digital flexographic plate by adding oxygen barrier layer. The technology of digital flexographic plate is not mentioned.

[0214] In the embodiment of oxygen barrier layer, the following components are used:

[0215] Polyvinylpyrrolidone K120 75

[0216] Polyvinylamine, molecular weight 200,000 15

[0217] Polymerization inhibitor (phenolic compound), hydroquinone 5

[0218] Sodium dodecyl sulfonate 5

[0219] Preparation of oxygen barrier layer

[0220] Polyvinylpyrrolidone is prepared into an 8% aqueous solution. Under stirring (300-500 rpm), polyvinylamine (previously prepared into a 5% aqueous solution) is slowly added, then a 1% aqueous solution of hydroquinone (freshly prepared) is added, and finally sodium dodecyl sulfonate is added. After appropriate stirring, a coating liquid is obtained.

[0221] Preparation of plate material

[0222] The coating liquid of the oxygen barrier layer is coated on the photosensitive elastomer of Huaguang DR170LS with the protective film and black film removed by a 40# wire bar, and then the black film with the protective film removed is overlaid on the oxygen barrier layer; or the oxygen barrier layer is coated on the black film in the same way, and then overlaid on the photosensitive elastomer of Huaguang DR170LS. Heat at a temperature of 100-120°C for five minutes. Cool to room temperature to prepare the plate material.

[0223] Plate making method

[0224] Then, plate making is carried out like ordinary digital flexographic resin plate. For example, after back exposure, remove the protective film on the black film, laser image on ESKO CDI, expose for 15 minutes on the exposure machine of KeMao with ordinary UVA lamp tube (LED lamp bead main exposure result is better), and wash the plate on the ordinary online plate washing machine of KeMao at a washing speed of 160 mm / min (or on the platform plate washing machine), using the commercially available environmentally friendly washing liquid of Minchen (or tetrachloroethylene washing liquid, the volume ratio of tetrachloroethylene to n-butanol is 3:1). After baking the plate for 1.5 hours, post-expose for 5 minutes and remove the adhesive for 5 minutes.

[0225] Test the plate material:

[0226] 150lpi, 2% dot can be reproduced 0.2% without correction curve, solid part is smooth and clean.

[0227] Comparative Example

[0228] Flat-top dot plate material is realized by adding oxygen barrier layer on the basis of ordinary digital flexographic plate.

[0229] The oxygen barrier layer is formed by adding the following components in Huaguang digital flexographic plate:

[0230] Polyvinylpyrrolidone K100 100

[0231] Polyvinylamine, molecular weight 150,000 20

[0232] Sodium dodecyl sulfonate 5

[0233] Preparation of oxygen barrier layer

[0234] Polyvinylpyrrolidone is prepared into an 8% aqueous solution, and polyvinylamine (previously prepared into a 5% aqueous solution) is slowly added under stirring (300-500 rpm). Finally, sodium dodecyl sulfonate is added, and after appropriate stirring, a coating liquid is obtained.

[0235] Preparation of plate material

[0236] The coating liquid of the oxygen barrier layer is coated on the photosensitive elastomer of Huaguang DR170LS with the protective film and black film removed by using a 40# wire bar, and then the black film with the protective film removed is overlaid on the oxygen barrier layer. Alternatively, the oxygen barrier layer is coated on the black film in the same way, and then overlaid on the photosensitive elastomer of Huaguang DR170LS. Heating is carried out at a temperature of 100-120°C for 5 minutes. After cooling to room temperature, the plate material is prepared.

[0237] Plate making method

[0238] Then, plate making is carried out like ordinary digital flexographic resin plate. For example, after back exposure, the protective film on the black film is removed, laser imaging is carried out on the ESKO CDI, exposure is carried out on the Kemaotuo ordinary UVA lamp tube for 15 minutes (LED lamp bead main exposure result is better), and plate washing is carried out on the Kemaotuo ordinary online plate washing machine at a plate washing speed of 160 mm / min (or on the platform plate washing machine), using the commercially available sensitive morning environmentally friendly plate washing liquid (or tetrachloroethylene plate washing liquid, the volume ratio of tetrachloroethylene to n-butanol is 3:1). After plate baking for 1.5 hours, post-exposure is carried out for 5 minutes and adhesion removal is carried out for 5 minutes.

[0239] Test the plate material:

[0240] 150lpi, 2% dot can be reproduced 0.2% without correction curve, solid part is smooth and clean.

[0241] The above merely describes the preferred embodiments of the present application, but the protection scope of the present application is not limited thereto. It should be noted that, for those skilled in the art and any person skilled in the art, under the premise of not departing from the overall concept of the present application, according to the technical solutions and inventive concept of the present application, some equivalent replacements or changes, and several changes and improvements made, these should also be considered as the protection scope of the present application.

Claims

1. An oxygen barrier layer, characterized in that: The oxygen barrier layer is formed by an oxygen barrier agent, an adhesive, a coating aid, and a polymerization inhibitor; the oxygen barrier agent is polyvinylpyrrolidone, the adhesive is polyvinylamine, and the oxygen barrier layer contains 50-80% polyvinylpyrrolidone by mass percentage, the K value of polyvinylpyrrolidone is 100-150, the mass of polyvinylamine is 10%-50% of polyvinylpyrrolidone, the content of polymerization inhibitor is 0.1%-5% of the mass of polyvinylpyrrolidone, and the coating aid includes at least one of surfactant, leveling agent, or thickener.

2. The oxygen barrier layer according to claim 1, characterized in that: The polymerization inhibitor includes at least one of phenolic polymerization inhibitors, quinone polymerization inhibitors, aromatic nitro compound polymerization inhibitors, or inorganic compound polymerization inhibitors.

3. The oxygen barrier layer according to claim 2, characterized in that: The phenolic polymerization inhibitors are hydroquinone, resorcinol, catechol, or tert-butylcatechol; the quinone polymerization inhibitors are p-benzoquinone or tetrachlorobenzoquinone; and the inorganic compound polymerization inhibitors are sodium sulfate, ferric chloride, sodium sulfide, or ammonium thiocyanate.

4. A flexible plate with built-in flat-top dots, characterized in that: From top to bottom, it includes a protective layer, a laser-ablable mask layer, an oxygen barrier layer, a photosensitive elastomer, and a support, wherein the oxygen barrier layer is the oxygen barrier layer described in any one of claims 1-3.