JP4425700B2 - Multilayer flexographic printing plate and method for producing the same - Google Patents

Description

The present invention relates to a multilayer flexographic printing plate using a liquid photosensitive resin composition and a method for producing the same.

Flexographic printing is widely used because it can be printed on a wide range of substrates due to its flexible plate characteristics, and its operation on the printing site is easy. In particular, radical polymerization by irradiation with actinic rays is used. After the exposure step of curing only the photosensitive layer of the relief part by reaction, the uncured resin composition other than the relief part is dissolved and removed with a predetermined cleaning solution (developer) or mechanically removed by swelling and dispersing, A flexographic printing plate using a photosensitive resin composition obtained by a development process in which only a cured portion appears as a relief on the plate surface is characterized by excellent fine-relief image reproducibility and short plate-making time. Has greatly contributed to the expansion of applications.

In particular, printing for containers and packaging materials in which flexographic printing is preferably used, especially corrugated cardboard printing, in which the corrugated sheet is a corrugated sheet deformed in a wavy shape (hereinafter abbreviated as flute) with paperboard pasted on one or both sides, or Flexographic printing is characterized by the fact that there are irregularities on the sheet surface due to the laminated structure, and because the raw material uses many recycled raw materials such as newspaper and waste paper, the paper quality is rough and rough. Is a flexographic printing plate using a liquid photosensitive resin composition having a low plate making cost and a short delivery time.
The quality of flexographic printed matter is evaluated as an excellent printed matter that solid images (image areas for the purpose of uniform coloring) are free from ink rubbing and that character portions and halftone images are clearly reproduced. However, in corrugated cardboard printing with a high ink density and a large amount of ink supplied to the printing plate surface, printing is performed at a relatively high printing pressure in order to obtain solid ink crushing quality. Due to the thickening of the characters and the marginal phenomenon in which the ink around the printed image is thickly thick, there is a tendency that the fine character lacks clarity and the halftone image has poor gradation expression.

Furthermore, in corrugated cardboard printing, if the cardboard sheet chips and paper dust generated on the corrugated board printing site are attached to the surface of the printing plate, printing can be a cause of printing failure. Since it leads to a decrease, a printing plate with less deposits is desired.
In a flexographic printing plate using a liquid photosensitive resin composition , Patent Documents 1 to 4 disclose methods for solving such problems of printing quality and paper dust adhesion by the configuration of a printing plate in which a plurality of resin compositions are multilayered. This method is disclosed.

Patent Document 1 is a double-layered flexographic printing plate characterized in that the cured product of the relief surface resin composition is 10 degrees higher in shore hardness than the cured product of the lower layer resin composition. As an effect in corrugated cardboard printing, reduction of paper dust adhesion is cited.
Patent Document 2 is characterized in that the photopolymerization rate of the lower layer resin composition is about 15 to 200 times that of the relief surface layer resin composition , and the modulus of the cured product of both layers has a difference of at least about 3.5 kg / cm 2. In Example 9, in the case of a double-layered flexographic plate comprising a relief surface layer (3.18 mm) resin composition having a hardness of 22 degrees and a lower layer (3.18 mm) resin composition having a hardness of 50 degrees, in Example 9. In addition, it is said that solid coating in corrugated cardboard printing is excellent for a single layer plate made of a resin composition having a hardness of 22 degrees.
Patent Document 3 discloses a printing plate for improving printing dimensional accuracy and ink paste in corrugated bar code printing, in which the thickness of the cured surface resin composition is 0.2 to 3.0 mm, and Shore A hardness is 35 to 55. The thickness of the cured product of the lower layer resin composition is at least twice that of the cured product of the relief surface resin composition , and the Shore A hardness is low in the range of 5 to 20 degrees of the cured product of the relief surface resin composition. A two-layer flexographic printing plate is disclosed.

Further, Patent Document 4 discloses a multi-layered region formed by laminating resin compositions having different physical properties and a kind of resin composition as a printing plate that achieves the purpose of clearly printing the solid image ink crushing and fine characters and fine line portions. single-layer structure is disclosed a partially multilayered printing plate made of a mixture according to the object.
However, even if the techniques of Patent Documents 1 to 4 are used, there is little problem with paper dust adhesion during printing as the trend of cosmetic decoration of cardboard for the purpose of advertising announcements has been increasing in recent years. Demand for quality, that is, excellent crushability of solid image ink, minute convex character images and solid indented character images are printed clearly, halftone dot image area is bright, and the step phenomenon that occurs along the corrugated flute An improved liquid photosensitive flexographic printing plate for corrugated cardboard has not been obtained.
JP 54-92402 A JP 55-6392 A Japanese Patent Laid-Open No. 62-296142 JP-A-62-2288847

An object of the present invention, in a single printing plate, that the different resin composition to multilayer structure and the printed surface is in Rukoto selectively placed, provides a printing plate that may correspond to the requirements of a variety of printing precision is there. In addition, there are few problems related to paper dust adhesion during printing, excellent crushing properties of solid image ink, minute convex character images and solid indented character images are clearly printed, halftone dot image area is bright, and flute of cardboard The present invention provides a liquid photosensitive flexographic printing plate for corrugated board which improves the step phenomenon occurring along the same and a method for producing the same.

As a result of diligent research to solve such problems, the present inventors have found that in addition to the technology of multilayer flexographic printing plates in which resin compositions having different compositions in the thickness direction in the plate thickness are laminated over the entire image region, the printing plate It has been found that it is effective to dispose resin compositions having different compositions according to the image on the surface, and the present invention has been completed.

That is, the present invention is as follows.
1. In the entire image area, an upper layer composed of at least two kinds of liquid photosensitive resin compositions having different compositions used on the printing plate surface, and a lower layer composed of a liquid photosensitive resin composition having a composition different from that of the upper layer, A multilayer flexographic printing plate obtained by exposing and developing a laminate of two or more layers comprising :
Liquid photosensitive resin compositions having different compositions comprising at least two types constituting the upper layer are selectively disposed respectively.
Among the at least two kinds of liquid photosensitive resin compositions constituting the upper layer, at least one kind of liquid photosensitive resin composition contains a hydrogen abstraction type photoinitiator, and the liquid photosensitive resin constituting the lower layer A multilayer flexographic printing plate wherein the composition does not contain a hydrogen abstraction type photoinitiator .
2. Having the upper layer is constant thickness, the lower layer has a formation Li Kui constant thickness from a liquid photosensitive resin composition having a single composition, the photosensitive resin composition of the same composition between the upper layer and the lower layer 1. The object is characterized by the absence of continuous 1 A multilayer flexographic printing plate as described in 1.
3. Any hardness at the time of two or more kinds of liquid photosensitive resin composition is photocured constituting the upper layer is higher than the hardness when the liquid photosensitive resin composition constituting the lower layer is photocured Characterized by Or 2. A multilayer flexographic printing plate as described in 1.
4). Either insolubilizing the minimum exposure amount of the upper layer of two or more kinds of liquid photosensitive resin composition constituting the, being greater than insolubilized minimum exposure amount of liquid photosensitive resin composition constituting the lower layer 1. ~ 3. A multilayer flexographic printing plate according to any one of the above.

5). Of the two or more types of liquid photosensitive resin compositions constituting the upper layer , at least the liquid photosensitive resin forming the solid image surface region contains a hydrogen abstraction type photoinitiator. ~ 4. A multilayer flexographic printing plate according to any one of the above.
6). 1. The hydrogen abstraction type initiator is benzophenone . ~ 5. A multilayer flexographic printing plate according to any one of the above.
7). 1. ~ 6. A method for producing a multilayer flexographic printing plate according to any one of
(A) unsaturated prepolymer, (b) an ethylenically unsaturated monomer, (c) a liquid photosensitive resin composition A, a liquid photosensitive resin composition B each comprising a photopolymerization initiator and having different compositions , Using the liquid photosensitive resin composition C,
(1) A process of applying the liquid photosensitive resin composition A with a thickness of X mm or less to an arbitrary area of the image area through a protective film (upper layer 1 coating process)
(2) Step of applying the liquid photosensitive resin composition B to the entire image area from above, and then making the thickness of the entire coating resin composition constant using a doctor blade at intervals of X mm on the protective film (upper layer 2 Coating process)
(3) Further, after the liquid photosensitive resin composition C is applied to the entire image area from above, the thickness of the entire applied resin is made constant using a doctor blade at intervals of Ymm on the protective film (lower layer coating) Process)
(Here, X and Y represent numerical values that satisfy the relationship of 0.05 ≦ X <Y ≦ 10.)
Molding and exposure steps including a development step seen including, among the liquid photosensitive resin compositions A and B, at least one of containing hydrogen abstraction type photoinitiators, liquid photosensitive resin composition C is hydrogen abstraction type light multi layer flexographic printing plate manufacturing method of you characterized by containing no initiator.

Multilayer flexographic printing plate of the present invention, in a single printing plate, in Rukoto different resin composition to multilayer structure and the printing surface is selectively disposed, it may correspond to the requirements of a variety of printing accuracy. In addition, the multilayer flexographic printing plate of the present invention has few problems related to paper dust adhesion during printing, has excellent crushing properties of solid image ink, fine convex character images, solid indented character images are clearly printed, and halftone dots The method for producing a multilayer flexographic printing plate according to the present invention has an effect of obtaining a printed matter with a bright image portion and improved stepping phenomenon generated along the flute of the cardboard. It has the effect of making it possible to manufacture.

Hereinafter, the present invention will be described in detail with a focus on preferred embodiments.
One aspect of the present invention is a flexographic printing plate constituted by a novel lamination mode.
The liquid photosensitive resin composition that can be applied to the multilayer flexographic printing plate of the present invention is not particularly limited, but as a representative one, unsaturated having at least one polymerizable double bond in the molecule. A photosensitive resin composition containing a prepolymer, a photopolymerization initiator, and an ethylenically unsaturated monomer having a polymerizable double bond. Examples of the unsaturated prepolymer include unsaturated polyester, unsaturated polyurethane, unsaturated Examples thereof include polyamides, unsaturated polyacrylate resins, unsaturated polymethacrylate resins, and various modified products thereof. Specifically, for example, Japanese Patent Publication No. 51-37320, No. 01-245245, JP-A No. 04-095959, JP-A No. 3-157657, JP-A No. 07-295218, Fair 02-010165, JP-can be exemplified those described in JP-B 55-034930 and JP Hei 10-153858.

Liquid photosensitive resin composition used in the present invention exhibits fluidity in a temperature range below molding-exposure step, and more preferably has a viscosity in the range of 1~200Pa · s. The viscosity not lower than 1 Pa · s, it is difficult to make constant the thickness of each resin composition layer when the molding and exposing the multi-layer flexographic printing plate of the present invention, the multilayer in viscosity that exceed 200 Pa · s Since a longer waiting time is required for making the overall plate thickness constant after the structure is molded, a more preferable viscosity range is 10 to 150 Pa · s.
Moreover, it is preferable that the viscosity of the plurality of resin compositions used in the multilayer flexographic plate is approximately constant.

The multilayer flexographic printing plate of the present invention can be realized preferably by subjecting a laminate of liquid photosensitive resin compositions of three or more different compositions to a molding / exposure step, and a liquid photosensitive resin composition of the different compositions and That is, a prepolymer having at least one polymerizable double bond in the molecule, which is an essential component of the liquid photosensitive resin composition , a photopolymerization initiator, and an ethylenically unsaturated monomer having a polymerizable double bond The composition using raw materials having different chemical structures, or the composition is different in composition ratio, and further can be added to the liquid photosensitive resin composition as appropriate. Thermal polymerization stabilizer, ultraviolet absorber, light stabilizer, chain The use of different compounds for transfer agents, dyes, pigments, lubricants, inorganic fillers, surfactants, plasticizers, hydrolysis inhibitors, etc. can also be an element of the difference in the resin composition .

In order to achieve the excellent print quality that the multilayer flexographic printing plate of the present invention is the purpose of, it is important that the different liquid photosensitive resin composition applied results in different physical properties, for example, In the exposure and molding process, photopolymerization speed, photocured product hardness, rebound resilience, swelling and wettability to various solvents, stability when stored for a certain period of time, mechanical property stability, lubricant precipitation, The composition of the liquid photosensitive resin that expresses the physical properties is not limited at all.
In particular, in the multilayer flexographic printing plate of the present invention, a resin composition having different photopolymerization speed, photocured product hardness, and wettability to various solvents is multilayered vertically in the thickness direction of the printing plate, and two or more types are also formed on the plate surface. It is effective to selectively dispose different resin compositions depending on the printing design, and the difference in physical properties preferable for improving the printing quality will be described in more detail.

First, the difference regarding the hardness of the photocured product will be described.
In a printing plate manufacturing method using a photosensitive resin composition, in a plate configuration in which resin compositions having different hardnesses of a photocured product are stacked one above the other, a high hardness composition is used for the upper layer constituting the printing plate surface. A method of suppressing character thickening due to printing of dot images and fine convex characters is known, and the same technique can be used in the flexographic printing plate of the present invention.
When resin compositions having different hardnesses are used in the multilayer flexographic printing plate of the present invention, for example, a halftone dot image on the printing plate surface, a resin composition _A that expresses photocured product hardness Ha _A in fine convex character areas, Multilayer flexographic printing plate comprising resin composition _B expressing photocured material hardness Ha _B in other regions including solid images, and resin composition C expressing photocured material hardness Ha _C as a lower layer. When preparing the above, it is preferable that the respective photocured product hardnesses Ha _A , Ha _B , and Ha _C have a relationship of Ha _A > Ha _B ≧ Ha _C.

The hardness of the photocured product of the liquid photosensitive resin composition used for the printing plate is generally represented by the Shore A hardness measured with a teclock type durometer, which will be described later. The object hardness will be described in more detail by Shore A hardness.
Halftone image surface of the printing plate, the photocured product hardness Ha _A resin composition A to place the small print area, the photocured product hardness Ha _B of the resin composition B be located in other areas, including a solid image area On the other hand, it is preferably large in the range of 5 to 40 degrees. When the hardness difference between Ha _A and Ha _B is less than 5 degrees, it is difficult to obtain the effect of eliminating halftone dot images in corrugated cardboard printing and the effect of improving the resolution of fine characters, which are the effects of the present invention. When it is larger than the range, halftone dots and ink distortion of fine convex character images are likely to occur. Therefore, it is more preferable that Ha _A is larger than Ha _{B in} the range of 10 to 30 degrees.

The photocured material hardness Ha _B of the resin composition B arranged in the area including the halftone image and the solid image area other than the fine convex character area is the photocured material hardness Ha _{C of the} resin composition C constituting the lower layer area of the entire printing plate. On the other hand, in order to obtain a solid image ink crushing excellent in cushioning effect due to the hardness difference between the upper and lower layers, it is preferably larger in a range of less than 25 degrees. When the hardness difference between Ha _B and Ha _C is less than 3 degrees, the cushioning effect is difficult to appear, and when it exceeds 25 degrees, ink blur of a solid image is likely to occur. Therefore, Ha _A is 5 degrees to Ha _B. It is more preferable that it is large in the range of 20 degrees.
It is preferable that the photocured product hardness Ha _C of the resin cured product C constituting the lower layer region of the entire printing plate is in the range of 15 to 45 degrees. When the hardness is less than 15 degrees, stress against printing pressure is not expressed and solid ink crushing may be insufficient. When the hardness exceeds 45 degrees, the cushioning effect against the resin composition on the printing plate surface is less likely to occur. The cured product hardness Ha _C is more preferably in the range of 20 to 40 degrees.

Next, the photopolymerization rate will be described.
In a printing plate manufacturing method using a photosensitive resin composition, in a plate structure in which resin compositions having different photopolymerization rates are laminated in two upper and lower layers, a resin composition having a lower polymerization rate than the lower layer resin composition It is known that a relief in which image thickening due to exposure is suppressed can be obtained by using for the upper layer portion, and the same technique can be used in the present invention.
The photopolymerization rate of the liquid photosensitive resin composition used in the printing plate is determined by methods analogous to those described as TO method (Thickness optimization method) in Japanese Patent No. 3158369, a liquid photosensitive resin composition Expressed as the minimum exposure (mJ / cm ² ) required to chemically insolubilize the aqueous solution.

When using a multi-layer flexographic printing plate to a different resin composition of the photopolymerization rate of the present invention, for example, the halftone image surface of the printing plate, the resin composition A having insolubilizing minimum exposure amount Q _A fine character area, the printing plate surface A multilayer flexographic printing plate in which a resin composition _B having an insolubilized minimum exposure amount QB is disposed in other areas including a solid image and a resin composition _C having an insolubilized minimum exposure amount QC is disposed below them. when creating each insolubilized minimum exposure amount _{Q a,} Q B, the relationship of _{Q C} is preferably designed _{Q a} ≧ _Q B> _{Q C} is established as.
Between the resin composition A and the resin composition B located on the printing plate surface and the resin composition C constituting the printing plate lower layer region, Q _A or Q _B is substantially the same as Q _C or more than 10 times It is preferable that it is large within a small range.

When Q _A or Q _B is greater than 10 times the Q _C is profiled relief by flow phenomena during the curing reaction of the liquid resin composition is likely to occur in the halftone image, the solid image stickiness occurred Sometimes it is, in designing the photocuring properties of the upper region and a lower region forming the expected printing surface high-definition of the printing plate relief, 1.5 times Q _a or Q _B against Q _C It is more preferable to adjust within a range of ˜5 times.
On the other hand, between the resin composition A and the resin composition B located on the printing plate surface, which is a feature of the present invention, Q _A and Q _B are substantially the same or Q _A is large in a range less than 5 times Q _B It is preferable. If Q _B is greater than Q _A, may halftone image, the effect of obtaining a high-definition printing plate relief in fine print area not enough, when Q _A is large in a range exceeding 5 times the Q _B, a resin composition Since it may be difficult to balance the image reproducibility of the A region and the resin composition B region, it is more preferable that Q _A and Q _B are substantially the same or Q _A is larger in a range less than three times Q _B.

The difference in composition regarding the photopolymerization rate used in the multilayer flexographic printing plate of the present invention is not only the minimum insolubilization exposure measured by the TO method, but also the difference in the influence of oxygen inhibition of radical reaction on the plate surface, that is, the air curing property. Differences and differences in reactivity to post-exposure by germicidal lamps performed after development can also be included, and these have a great effect on tackiness removal by promoting the crosslinking reaction of the printing plate surface, during printing It is important to obtain a plate with less paper dust adhesion.
The resin composition for accelerating the crosslinking reaction on the printing plate surface preferably contains a hydrogen abstraction type photoinitiator. For example, substituted or unsubstituted benzophenones , substituted or unsubstituted aromatic ketones, o, p -Quinone compounds, substituted or unsubstituted thioxanthones, etc. are mentioned. Among them, benzophenones are generally used, and benzophenone is the most effective.

However, since benzophenone has a high absorptivity of actinic rays, corrugated cardboard printing having a plate thickness of several millimeters when it is included in the composition until the stickiness of the solid image portion, which has the greatest effect on paper dust adhesion, is sufficiently reduced. It may be difficult to obtain a good relief shape in the plate.
In the multilayer flexographic printing plate of the present invention, resin compositions having different surface reactivity that affect the adhesion on the printing plate surface are arranged according to the image, that is, a solid image having a large problem of paper dust adhesion contains benzophenone. place the resin composition was placed, the surface area is small paper dust hardly convex character or halftone image area adhering to select a resin composition having a photoinitiator composition having excellent relief reproducibility without the benzophenone In addition, it is possible to realize high definition of the printing quality that has been sacrificed for removing the tackiness of the plate surface.

As the resin composition used on the plate surface of the multilayer flexographic printing plate of the present invention, it is also preferable to dispose resin compositions having different wettability with respect to ink according to the image.
The wettability of the cured product of the photosensitive resin composition to the ink is determined by the relative relationship between the surface free energy of the ink and the surface free energy of the printing plate surface. For example, the surface of an aqueous ink generally used for corrugated cardboard printing The free energy is in the range of approximately 40 to 50 dyn / cm, and the flexographic printing plate made of the photosensitive resin composition has a surface free energy of 40 to 65 dyn / cm.
In the multilayer flexographic printing plate of the present invention, when resin compositions having different surface free energies are arranged as the plate surface resin composition , printing is performed with a large amount of ink placed on the solid image area, and less ink in the halftone and fine print image areas. In order to achieve this, it is preferable that the difference in surface free energy of the cured product of the resin composition is 5 dyn / cm or more on each plate surface.
In the range where the difference in surface free energy is less than 5 dyn / cm, the effect of improving the printing quality may not be sufficient, and in the case of a combination exceeding 30 dyn / cm, the density of the ink may become apparent from the difference in ink acceptance transferability. Therefore, it is more preferable to set the difference in surface free energy in the range of 10 to 20 dyn / cm.

  As described above, the various resin compositions used in the multi-layer flexographic printing plate of the present invention mainly include the photopolymerization rate, the hardness of the photoreaction cured product, and the surface free energy of the plate surface obtained by plate making. It is important to select them appropriately between the image regions or between the upper and lower laminated structures according to the purpose of improving the print quality.

The multilayer flexographic printing plate of the present invention intends to express each characteristic of different resin compositions in a composite manner in the same printing plate, and has different composition as described above, preferably physical properties in the entire image area. What is particularly limited except that the photosensitive resin composition has a multi-layered structure of at least two layers and a mixture of at least two types of plate surfaces having different physical properties. Although there is no constant thickness, the composition is laminated so that at least two kinds of liquid photosensitive resin compositions having different compositions as described above, preferably having different physical properties, are mixed on the printing plate surface in the entire image area. It is preferable that the multi-layered structure is composed of a lower layer made of a liquid photosensitive resin composition of a single composition having a constant thickness.

An upper layer having a constant thickness formed by selectively disposing at least two kinds of liquid photosensitive resin compositions on the surface of the printing plate can be produced by the technique of Patent Document 4, and the composition and physical properties of the upper layer are further increased. By laminating resin compositions having different properties, it is possible to realize excellent print quality by a composite effect of preferably three or more types of resin compositions having different properties.
Three-layer structure in which an intermediate layer is provided between the upper layer and lower layer near the printing plate surface in the thickness direction of the plate thickness, and resins having different hardness depending on the relief image for the purpose of further improving the cushioning effect in the lower layer Although it is possible to arrange a plurality of compositions, in order to realize workability in the molding process described later, excellent thickness accuracy, and entrainment of bubbles in the molding process, which is an essential problem of the liquid photosensitive resin composition In order to prevent this, the two layers of the liquid photosensitive resin composition are laminated so that they are mixed on the surface of the printing plate, and the lower layer is composed of a single layer of the liquid photosensitive resin composition having a constant thickness. More preferably, the multilayer structure is made of

The multilayer flexographic printing plate of the present invention preferably has a plate thickness in the range of 2 mm to 10 mm, and is often required to have a relief depth of about 1.5 mm or more in order to cope with cardboard printing. Since a corrugated cardboard printing machine generally has a specification of about 7 to 8 mm as a thickness of a printing plate produced by attaching a flexographic printing plate part to a carrier sheet, a more preferable plate thickness is 2.5. It is the range of -8.0 mm.
The thickness of the cured product of the resin composition of the upper layer disposed on the printing plate surface of the multilayer flexographic printing plate of the present invention is more than 0.05 mm and about 1/3 or less of the total thickness of the printing plate, At the same time, the thickness of the lower layer is preferably about 2/3 or more. If the thickness is less than 0.05 mm, the characteristics of the elastic properties due to the difference in hardness hardly appear, and if the thickness is more than 1/3 of the total thickness of the printing plate, the sensitivity difference between the upper and lower resin composition layers is increased with the expectation of improving the reproducibility of relief. Therefore, the thickness of the cured product of the resin composition of the upper layer disposed on the printing plate surface is preferably more than 0.1 mm and about 1/4 or less with respect to the entire printing plate thickness, The range of 1.0 mm is most preferable.

In the upper layer arranged on the surface of the printing plate, a plurality of resin compositions having different compositions are arranged according to the image, and the thickness between the adjacent resin compositions is substantially the same, or the upper layer is also a laminated structure It is preferable to arrange so that it has.
For example, for the resin composition A and the resin composition B having a lower photocured product hardness than the resin composition A, the halftone image, the resin composition A in a fine character region, and the other region including a solid image on the printing plate surface When the resin composition B is disposed, the thickness of the resin composition A, which is highly required to be selectively disposed, is reduced, and the resin composition B includes the thickness of the resin composition A with respect to the entire plate-making image. As a result, a laminated structure is formed in both the upper layer and the very thin film by coating so as to have a constant thickness. Especially in the case of a configuration characterized by a hardness difference, the resin composition disposed in the lower layer The hardness change in the thickness direction including the hardness becomes gradual, and further improvement of the elastic characteristics can be obtained.

A schematic diagram of the multilayer flexographic printing plate of the present invention is shown in FIG. 3, and a schematic diagram of the multilayer flexographic printing plate obtained by the prior art is shown in FIGS. 4 (a) and 4 (b).
Another aspect of the present invention is a novel method for producing a corrugated cardboard multilayer flexographic printing plate comprising a liquid photosensitive resin composition, which will be described in detail below.
In general , a flexographic printing plate production method using a liquid photosensitive resin composition is performed by a plate making method including a molding / exposure step, a development step, and a post-exposure step.
The method for producing a multilayer flexographic printing plate of the present invention is characterized by its molding / exposure process, and a development process, a post-exposure process, and other processes added according to the purpose, such as a drying process, a surface treatment process, etc. Can be added as appropriate.

Hereinafter, preferable examples of the molding / exposure process, the development process, and the post-exposure process will be described.
<Molding / exposure process>
(1) A process in which a negative film is placed on a UV transparent glass plate and covered with a thin protective film, and then the liquid photosensitive resin composition A is applied to a predetermined place with a thickness of X mm or less (upper layer 1 coating) Process)
(2) Next, after the liquid photosensitive resin composition B is applied to the entire image area, the thickness of the entire applied resin composition is made constant using a doctor blade at an interval of X mm on the support (the upper layer 2 coating) Construction process)
(3) Further, after the liquid photosensitive resin composition C is applied to the entire image area from above, the thickness of the entire applied resin composition is made constant using a doctor blade at intervals of Ymm on the support (lower layer) Coating process)
(Here, X and Y represent numerical values that satisfy the relationship of 0.05 ≦ X <Y ≦ 10.)
(4) A process of attaching a base film to be a support (support laminate process),
(5) Molding process that regulates the thickness by compressing with a glass plate that is transparent to ultraviolet rays through a spacer so that the entire thickness of the laminate of all liquid resin compositions becomes a constant plate thickness
(6) A laminate of a liquid resin composition is irradiated through a support with actinic rays (having a wavelength distribution of 300 nm or more) using an ultraviolet fluorescent lamp as a light source, and a uniform thin cured resin composition is formed on the entire surface of the support on the plate. Back exposure process for depositing physical layer, that is, floor forming layer (back deposition layer)
(7) Consists of a method including a relief forming exposure process in which an image is formed by irradiating a laminate of a liquid resin composition with an actinic ray (having a wavelength distribution of 300 nm or more) using an ultraviolet fluorescent lamp as a light source through a negative film. .

When the thickness of the printing plate used for corrugated cardboard printing is 4 mm or more, a plate making system using a liquid photosensitive resin composition is realized in order to realize an appropriate relief depth to supplement the strength of the relief against the printing pressure during printing. In order to maximize the advantage of reusing the uncured resin composition , a method in which the back deposition layer is formed in two stages is used, that is, it is preferable to form a shelf layer as a base, in which case relief exposure is performed. It is preferable to perform a masking exposure process using a dedicated masking film from the upper glass side before.
In the above upper layer 1 coating step, it is necessary to apply anywhere in selective liquid resin composition with the following degrees of thickness 1mm in accordance with the image, the liquid resin composition upon application is 1 In the case of a viscosity of about 10 Pa · s, a brush can be applied, but since there is a possibility that air bubbles may be mixed in , it is difficult to use a resin composition having a viscosity exceeding 10 Pa · s, and a tube bottle provided with a flat projection port A method in which a liquid resin composition is filled and applied to a predetermined place, or a method in which a resin composition temporarily applied from a tube bottle is stretched to a certain thickness with a spatula is preferable.

FIG. 1 shows a schematic diagram of the process of applying the resin composition only to the fine line and halftone dot image portions.
For the above-described upper layer 2 coating step, lower layer coating step, and support laminating step, in the plate making machine having the function of laminating and applying two types of resin compositions , the steps are continuously performed by the same operation. Examples of the plate making apparatus having such a function include an ASF-913E type exposure machine (trademark: manufactured by Asahi Kasei Chemicals Corporation) and an AWF-110E type exposure machine (trademark: manufactured by Asahi Kasei Chemicals Corporation). Can do.
By carrying out the upper layer 2 coating step and the lower layer coating step continuously in the same operation, a photosensitive resin composition having the same composition is continuously present between the upper layer and the lower layer. A multilayer flexographic printing plate is obtained.

FIG. 2 shows a schematic diagram of a process in which a printing plate upper layer is applied to a plate making image area other than a fine line and halftone dot image, and then a printing plate lower layer is applied and the support is laminated.
<Development process>
In the method for producing a relief printing plate using a negative photosensitive resin composition, a developing step is required as an operation for removing a portion other than a relief image cured by a photoreaction, and an unreacted resin composition that is not exposed is dissolved or dissolved. It is necessary to use a liquid having the ability to swell as a developer and remove it from the printing plate surface.
As a developer for a liquid photosensitive resin composition , a surfactant aqueous solution is generally used, and an optimal surfactant or liquid composition is selected according to the properties of the resin composition to be used. There is no particular limitation.
As a developing method, a method of immersing the exposed photosensitive resin composition in a developer, a method of spraying the developer on the exposed photosensitive resin composition plate surface from a spray nozzle , and dissolving and removing the uncured resin composition , or Examples thereof include a method of scraping an uncured resin composition swollen by dipping / spraying with a brush.

<Post-exposure process>
Post-exposure step in the printing plate production method according to a liquid photosensitive resin composition, by irradiating again actinic rays to the cured product of the obtained photosensitive resin composition as a relief image by a developing process, curing of the photosensitive resin composition This is done for the purpose of accelerating the photocrosslinking reaction of unreacted polymerizable double bonds remaining on the surface of the product or inside. Is called.
The active light used in the post-exposure process is an active light source having a distribution in a wavelength region of 300 nm or more similar to that used in the molding / exposure process (for example, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, an ultraviolet fluorescent lamp, a carbon arc lamp, xenon). It is preferable to use an active light source (for example, a low-pressure mercury lamp, a germicidal lamp, a deuterium lamp, etc.) having a distribution in a wavelength region of 200 to 300 nm.
The post-exposure process may be performed by an underwater exposure method for the purpose of preventing polymerization reaction inhibition by oxygen in the air, or by exposure in the air, that is, a method that does not take measures against oxygen inhibition (air exposure method). May be. In the case of a liquid photosensitive resin composition, it is preferable to use an underwater post-exposure method as a more effective post-exposure method, and it is also possible to actively carry out an aerial exposure method after performing post-exposure by an underwater exposure method. It is effective as a surface treatment method by using.

The present invention will be described based on examples. However, the present invention is not limited to these examples.
<Adjustment of resin composition and measurement of physical properties>
A liquid photosensitive resin composition was prepared and prepared by the following method.
Production Example 1 Production of Unsaturated Prepolymer A 1000 g of poly (3-methyl-1,5-pentanediol adipate) diol (hydroxyl value: 37 KOH mg / g) and 1000 g of polyoxyethylene (EO) -oxypropylene (PO) ) Add 45 ppm of dibutyltin dilaurate (hereinafter abbreviated as BTL) to a mixture with a block copolymerized diol (hydroxyl value: 44 KOH mg / g, EO content 30 wt%) and stir until uniform at 40 ° C. Next, 148.5 g of tolylene diisocyanate (hereinafter abbreviated as TDI) was added and further stirred. When uniform, the mixture was heated to 80 ° C. and reacted for about 4 to 5 hours to form isocyanate groups at both ends. It was set as the prepolymer precursor which has. Further, 436.0 g of poly (oxypropylene) glycol monomethacrylate (average molecular weight 380, hereinafter abbreviated as PPMA) was added and reacted for about 2 hours, and then a part of the sample was taken out and isocyanate was measured by an IR spectrometer. After confirming the disappearance of the group, a polyurethane-based unsaturated prepolymer A having a number average molecular weight of 17,000 determined by GPC was obtained.

Production Example 2 Production of Unsaturated Prepolymer B 1000 g of poly (3-methyl-1,5-pentanediol adipate) diol (hydroxyl value: 37 KOH mg / g) and 1000 g of polyoxyethylene (EO) -oxypropylene (PO) ) Add 45ppm BTL to the mixture with block copolymerized diol (hydroxyl value: 44KOHmg / g, EO content 30wt%) and stir until uniform at 40 ° C, then add 189.5g TDI and stir further When the temperature became uniform, the temperature was raised to 80 ° C. and the reaction was allowed to proceed for about 4 to 5 hours to obtain a prepolymer precursor having isocyanate groups at both ends. After adding 462.5 g of PPMA and reacting for about 2 hours, a sample was partially taken out and the disappearance of isocyanate groups was confirmed with an IR spectrophotometer, and the polyurethane unsaturated prepolymer having a number average molecular weight of 8500 determined by GPC was used. Polymer B was obtained.

The compositions shown in Table 1 were prepared in the unsaturated prepolymers A and B obtained, and resin compositions 1 to 5 were obtained by stirring and mixing at 60 ° C. for about 2 hours. In Table 1, “resin compositions” 1 to 5 are labeled “resins” 1 to 5 for convenience.
The method used in order to evaluate the viscosity of the liquid photosensitive resin composition prepared below, a photosensitive characteristic, and hardness is demonstrated.
1) Viscosity measurement method The prepared liquid photosensitive resin composition is left in a constant temperature and humidity room at a temperature of 20 ° C. and a humidity of 70% for one day, and a B-type viscometer type B8H (manufactured by Tokyo Keiki Co., Ltd.) is used in the room. The viscosity was measured.

2) Photocuring characteristics measurement by TO (thickness optimization) method 2-1) Sample molding Two 5 mm thick glass plates (transmittance of about 80%) are prepared, and one of them is covered and covered with a transparent polyethylene film, An 8 mm thick mold having an opening of 30 mm × 150 mm was placed thereon, and the liquid photosensitive resin composition was filled in the mold. Next, after covering the surface of the liquid photosensitive resin composition with a polyethylene terephthalate film (support, approximately 80% transmittance) having a single-sided adhesive layer cut into a mold size, the other 5 mm thick glass The glass plates were sandwiched with clips using a plate, and left for a while in a light-shielded state at a room temperature of about 25 ° C. until the thickness of the liquid resin composition became constant, to obtain a TO exposure sample.

2-2) Exposure machine As a light source, an ultraviolet fluorescent lamp having a central wavelength region at 370 nm was arranged in parallel so that there was no uneven illumination, and used as an exposure machine. A movable sample base is provided under the exposure machine, and it is confirmed that the lamp illuminance is stable at a room temperature of 25 ° C., and measured at the height of the surface of the sample resin composition with an ultraviolet ray measuring device UV-M02 (trademark, manufactured by Oak Manufacturing). The lamp output and the sample stage height were adjusted so that the irradiation dose at a wavelength of 350 nm was 0.8 mW / cm ² .

2-3) side by side shielding rubber plate 30 mm × 60 mm glass plates mold portion on the support side of the exposure TO exposure samples arranged, that the liquid photosensitive resin composition in the mold is completely covered confirmed. This operation needs to be performed at a location away from the exposure machine so that exposure is not performed during the operation. And the TO exposure sample which covered the resin composition with the rubber plate was moved to the sample stand under the exposure machine, and arranged so that the rubber plates were arranged in a horizontal row.
The exposure is performed by sequentially removing the light shielding rubber plate at times of 0 seconds, 60 seconds, 120 seconds, 180 seconds, and 240 seconds, and a rubber plate that shields the entire TO measurement sample when 300 seconds have elapsed after the start of exposure. Exposure was completed by placing on the sample. Consequently will have been exposed at dose of ^{48mJ / cm 2, 96mJ / cm} 2, 144mJ / cm 2, 192mJ / cm 2, 240mJ / cm 2 in the TO measurement sample surface.
2-4) Development Developer W-10 (trademarks) useful for developing unsaturated prepolymers A and B in an AL-400W type developer (trademark, manufactured by Asahi Kasei Chemicals Corporation, drum type spray developer) Asahi Kasei Chemicals Co., Ltd., anionic surfactant aqueous solution) 1.5 wt%, surface treatment agent A-10 (trademark Asahi Kasei Chemicals Co., Ltd., benzophenone-containing nonionic surfactant aqueous solution) 0.5 wt% An aqueous solution to which 0.3 wt% of foaming agent SH-4 (trademark, manufactured by Asahi Kasei Chemicals Co., Ltd.) was added was prepared, and the developer temperature was 30 ° C., the spray pressure was 0.2 MPa, and the development time was 10 minutes. Development was carried out.

2-5) Post-exposure Light source in underwater post-exposure using ALF-200UP type post-exposure machine (trademark, manufactured by Asahi Kasei Chemicals Co., Ltd.) equipped with both UV fluorescent lamp and germicidal lamp. The exposure was performed at an exposure time at which the exposure amount irradiated from the surface of the cured product of the liquid photosensitive resin composition was 2500 mJ / cm ² .
2-6) Drying step Drying was performed for about 10 minutes with ALF-DRYER (trademark, manufactured by Asahi Kasei Chemicals Corporation) until there was no moisture on the plate surface.
2-7) Calculation of Q value The dried TO cured product was cooled to room temperature, and the thickness of the cured product of the resin composition was measured using a plate thickness meter with a contact surface of 10 mmφ having a pushbull gauge at a load of 200 g. .
The relationship between irradiation exposure dose (mJ / cm ² ) and plate thickness (/ 100 mm) is illustrated from the measurement results, and the minimum necessary for chemically insolubilizing the liquid photosensitive resin composition in the developer from the graph An exposure Q value (mJ / cm ² ) was derived.

3) Shore A hardness measurement method A 7 mm printing plate using the prepared resin composition alone was prepared by the same method as the method for producing the evaluation printing plate described later.
A sample piece in the solid image area is left in a constant temperature and humidity room at a temperature of 20 ° C. and a humidity of 70% for one day. , ISO: 7619A) under a 1 kg load, and a value 15 seconds after the start of the measurement was obtained as the Shore A hardness.

<Method for producing evaluation printing plate>
The printing plate was created using the liquid photosensitive resin composition prepared in order to confirm the effect of this invention, and the result of having evaluated the quality of the printed matter is shown.
The image used to create the printing plate is an image having the same Mincho concave character in the middle of a 30 cm square solid image, A negative having 30 L square 30 LPI (unit indicating the number of 1 cm 2 area divided vertically and horizontally) and a halftone gradation image with a density of 5 to 90% was produced on a silver salt film and used.
The printing plate manufacture is equipped with an 80 W ultraviolet fluorescent lamp having a central wavelength region at a wavelength of 370 nm as a molding / exposure process, and the light irradiation intensity through glass measured by an ultraviolet ray measuring device UV-M02 (trademark, manufactured by Oak Manufacturing). Using an AWF-110E type plate making machine (trademark, manufactured by Asahi Kasei Chemicals Co., Ltd.) with an upper part of 4.5 mW / cm ² and a lower part of 5.5 mW / cm ² , a relief with a halftone dot gradation pattern of 5% is completely formed. The relief exposure amount to be performed is optimized, and the subsequent recovery process, development process, and drying process of the uncured resin composition are performed after the AWF-110W recovery / cleaning / drying machine (trademark, manufactured by Asahi Kasei Chemicals Corporation) The exposure process is a development process in which a post-exposure unit of AWF-110E type plate making machine (trademark, manufactured by Asahi Kasei Chemicals Co., Ltd.) is measured by photocuring property measurement by the TO method, a post-exposure process, It was carried out by combining under conditions analogous to the conditions of about 燥工.

<Evaluation method of evaluation printing plate>
The obtained printing plate was subjected to a corrugated cardboard printing test for the A-stage C liner using a JEM flexographic printing machine (trademark, manufactured by JEOL Ltd.), and each evaluation item was ranked according to the following evaluation criteria. Went.
Regarding the selection of appropriate conditions for corrugated cardboard printing, the ani pressure was driven by +0.05 mm from the pressure at which the ink from the anilox roll adhered to the entire plate surface, and the printing pressure was driven until the solid image was crushed. Condition.

Printing conditions; Ink: Super Wasser ZSL3 black (trademark, manufactured by Osaka Printing Ink Co., Ltd.)
Ink viscosity: 8-9 seconds / Zahn cup # 4 (20 ° C.)
Inking mechanism: Reverse doctor method
Anilox wire number: 250 LPI
Corrugated sheet: non-coated 175 g / m ² surface sheet, reinforced core
Printing speed: 65 sheets / min

a) Independent convex character print quality A: A state of clear printing up to 8 point characters B: A state where readable up to 8 point characters can be seen, but a slight marginal effect is observed C: Some characters of 9 points or less are partially due to ink bleeding Characters filled: D: Characters of 10 points or less are partially filled with ink. E: Characters of 12 points or less are partially filled with ink. B) Solid letter printing Quality A: A state in which up to 8 point characters can be read. B: A character of 10 points or less is partially filled with ink. C: A character of 12 points or less is partially filled with ink. D: Characters with 14 points or less are partially filled with ink. E: Characters with 16 points or less have one with ink bleeding. The part is full
c) Brightness of halftone dot, step phenomenon A: The state in which the steps are hardly noticeable and the overall density is printed brightly B: There are steps that are slightly visible, but the overall density is printed brightly C : Obvious step and the whole density printed slightly dark D: Obvious step and darkly printed flute

[Example 1, Example 2, Comparative Example 1, Comparative Example 2]
A negative film is placed on the lower glass of the AWF-110E type plate making machine (trademark, manufactured by Asahi Kasei Chemicals Co., Ltd.), covered with a 30 μm-thick polypropylene sheet (protective film), and the prepared resin composition 5 is the upper layer. convex character image so as to be 0.15mm thickness as the resin composition used in part 1 and placed in a halftone dot image area, and then using the resin composition 3 was prepared in the upper part 2 at an interval of 0.6mm resin Doctor squeegee is applied to the entire image area as a composition , and finally, the resin composition 1 is further applied from above to the entire image area as a resin composition used in the lower layer at an interval of 7.2 mm. Thereafter, the plate making steps were performed as described above to obtain a printing plate of Example 1.

Of the printing plate for Example 1 to obtain a printing plate of Example 2 in the same manner except that the resin composition 5 was coated as a resin composition for use in the upper portion 1 and 0.4 mm.
Of the printing plate for Example 2, was obtained a printing plate of Comparative Example 1 by the same method except that no resin composition 5 was applied as the resin composition for use in the upper part 1.
Of the printing plate for Example 2, was obtained a printing plate of Comparative Example 2 by the same method except that no resin composition 3 was applied as a resin composition for use in the upper part 2.
As a result of the corrugated board printing evaluation for the printing plates of Example 1, Example 2, Comparative Example 1, and Comparative Example 2, the printing plates of Examples 1 and 2 were smaller in convexity than the printing plate of Comparative Example 1. A good printed matter is obtained in which characters can be literate and the degree of halftone dots is reduced. In Comparative Example 2, the literacy of convex characters and the reduction of halftone dots in Comparative Example 1 are reduced. Although it was seen, the literacy of the concave character located in the center of the solid image was inferior, and a printing plate with a large stickiness was observed at the periphery of the solid image, and paper dust adhered.
Table 3 shows the resin composition and plate configuration, and Table 4 shows the evaluation results. In Table 3, “resin compositions” 1 to 5 are labeled “resins” 1 to 5 for convenience.

[Comparative Example 3]
Comparative Example 2, was obtained a printing plate of Comparative Example 3 in the same manner except applying a resin composition 2 as a resin composition for use in the lower layer portion.
The printing plate of Comparative Example 3, which addresses the issue of stickiness of the solid image peripheral portion of Comparative Example 2 is large, which benzophenone is contained in the resin composition 2 as a resin composition of the lower layer portion forming the solid image It was the effect that had been.
However, the printed matter obtained from the printing plate of Comparative Example 3 is generally inferior in print quality, which is uniform with no difference in the photocuring speed of the resin composition in the upper and lower layers, and further contains benzophenone. By using the resin composition in the lower layer region, it is presumed that the curing speed in the thickness direction is slow from the TO sensitivity curve, and the quality of the printing plate is due to the formation of an image having a shallow concave top.
Table 3 shows the resin composition and plate configuration, and Table 4 shows the evaluation results. In Table 3, “resin compositions” 1 to 5 are labeled “resins” 1 to 5 for convenience.

[Example 3, Example 4, Comparative Example 4]
About Example 2, the printing plate of Example 3 was obtained by the same method except apply | coating the resin composition 4 as a resin composition used for the upper layer part 1. FIG .
Image area for applying the resin composition 4 as a resin composition for use in the upper part 1 of Example 3, a convex character image, in addition to applying a thickness of 0.4mm to halftone dot image area, in the solid image A printing plate of Example 4 was obtained by the same method except that the coating was applied only to the concave character portion located in the center portion with a thickness of 0.15 mm.
The printed matter obtained from the printing plates of Example 3 and Example 4 is further improved in print reproducibility of convex characters and halftone images compared to the printed matter of Example 2, and the influence of marginal and step marks It became a printed matter without. In Example 4 in which the resin composition 4 was applied only to the solid character portion, the print quality of the concave characters was also improved.
On the other hand, for Example 4, was obtained a printing plate of Comparative Example 4 by the same method except that no resin composition 3 was applied as a resin composition for use in the upper part 2.
The printed matter obtained with the printing plate of Comparative Example 4 had a printing quality close to that of Example 4, but a printing plate with a large stickiness at the periphery of the solid image, and adhesion of paper dust was observed.
Table 3 shows the resin composition and plate configuration, and Table 4 shows the evaluation results. In Table 3, “resin compositions” 1 to 5 are labeled “resins” 1 to 5 for convenience.

[Comparative Example 5 and Comparative Example 6]
Comparative Example 1, was obtained a printing plate of Comparative Example 5 in the same manner except applying a resin composition 5 as a resin composition for use in the upper section 2 to the image region entirely.
Comparative Example 1, was obtained a printing plate of Comparative Example 6 in the same manner except applying a resin composition 4 as a resin composition for use in the upper section 2 to the image region entirely.
The printed matter obtained from the printing plates of Comparative Example 5 and Comparative Example 6 is equivalent to Comparative Example 1 in spite of the fact that a resin composition having a higher cured product hardness than that of Comparative Example 1 is disposed on the surface of the printing plate. The print quality was worse. This is a printing method in which an appropriate printing pressure is determined by crushing a solid image ink. In a structure in which a high-hardness resin composition is arranged over the entire solid image, a high appropriate printing pressure is required. Indicates that the print quality deteriorates.
In the printing plate of Comparative Example 6, at the same time, a printing plate with a large stickiness was formed at the periphery of the solid image, and adhesion of paper dust was observed.
The resin composition shown in Table 3, the plate structure, and the evaluation results are shown in Table 4. In Table 3, “resin compositions” 1 to 5 are labeled “resins” 1 to 5 for convenience.

  The multilayer flexographic printing plate and the method for producing the same according to the present invention can be suitably used especially in the field of cardboard printing among flexographic printing.

The conceptual diagram which shows the example of an upper layer 1 coating process. The conceptual diagram which shows the example of an upper layer 2 coating process, a lower layer coating process, and a support body lamination process. The conceptual diagram which shows the example of the multilayer flexographic printing plate of this invention. (A), (b) is a conceptual diagram which shows the example of the multilayer flexo plate by a prior art, respectively.

1: Photosensitive resin composition A
2: Photosensitive resin composition B
3: Photosensitive resin composition C
4: Negative film 4-a: Fine line portion on negative film 4-b: Halftone dot image portion on negative film 4-c; Solid image portion on negative film 5: Protective film 6: Glass plate transmitting actinic rays 7: Support 8: Doctor blade 9: Laminate roll

Claims (7)

In the entire image area, an upper layer composed of at least two kinds of liquid photosensitive resin compositions having different compositions used on the printing plate surface, and a lower layer composed of a liquid photosensitive resin composition having a composition different from that of the upper layer, A multilayer flexographic printing plate obtained by exposing and developing a laminate of two or more layers comprising :
Liquid photosensitive resin compositions having different compositions comprising at least two types constituting the upper layer are selectively disposed respectively.
Among the at least two kinds of liquid photosensitive resin compositions constituting the upper layer, at least one kind of liquid photosensitive resin composition contains a hydrogen abstraction type photoinitiator, and the liquid photosensitive resin constituting the lower layer A multilayer flexographic printing plate wherein the composition does not contain a hydrogen abstraction type photoinitiator . Having the upper layer is constant thickness, the lower layer has a formation Li Kui constant thickness from a liquid photosensitive resin composition having a single composition, the photosensitive resin composition of the same composition between the upper layer and the lower layer 2. The multilayer flexographic printing plate according to claim 1, wherein the product is not continuously present. Any hardness at the time of two or more kinds of liquid photosensitive resin composition is photocured constituting the upper layer is higher than the hardness when the liquid photosensitive resin composition constituting the lower layer is photocured A multilayer flexographic printing plate according to claim 1 or 2, wherein Either insolubilizing the minimum exposure amount of the upper layer of two or more kinds of liquid photosensitive resin composition constituting the, being greater than insolubilized minimum exposure amount of liquid photosensitive resin composition constituting the lower layer The multilayer flexographic printing plate according to any one of claims 1 to 3. 5. The liquid photosensitive resin forming at least a solid image surface region among two or more types of liquid photosensitive resin compositions constituting the upper layer contains a hydrogen abstraction type photoinitiator. The multilayer flexographic printing plate as described. The multilayer flexographic printing plate according to claim 1, wherein the hydrogen abstraction type initiator is benzophenone. A method for producing a multilayer flexographic printing plate according to any one of claims 1-6,
(A) unsaturated prepolymer, (b) an ethylenically unsaturated monomer, (c) a liquid photosensitive resin composition A, a liquid photosensitive resin composition B each comprising a photopolymerization initiator and having different compositions , Using the liquid photosensitive resin composition C,
(1) A process of applying the liquid photosensitive resin composition A with a thickness of X mm or less to an arbitrary area of the image area through a protective film (upper layer 1 coating process)
(2) Step of applying the liquid photosensitive resin composition B to the entire image area from above, and then making the thickness of the entire coating resin composition constant using a doctor blade at intervals of X mm on the protective film (upper layer 2 Coating process)
(3) Further, after the liquid photosensitive resin composition C is applied to the entire image area from above, the thickness of the entire applied resin is made constant using a doctor blade at intervals of Ymm on the protective film (lower layer coating) Process)
(Here, X and Y represent numerical values that satisfy the relationship of 0.05 ≦ X <Y ≦ 10.)
Molding and exposure steps including a development step seen including, among the liquid photosensitive resin compositions A and B, at least one of containing hydrogen abstraction type photoinitiators, liquid photosensitive resin composition C is hydrogen abstraction type light multi layer flexographic printing plate manufacturing method of you characterized by containing no initiator.