JP2011107654A - Method for preparing high-resolution flexographic printing plate and flexographic printing plate obtained by the method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the following problems in a conventional plate making method which has no plate making step or is not configured to remove oxygen existing on a plate surface in plate making: a curing reaction of a photosensitive resin layer in exposure is hindered by oxygen existing on a plate surface; and a flexographic printing plate with a high resolution relief formed thereon cannot be obtained. <P>SOLUTION: A high-resolution flexographic printing plate with a relief excellent in resolution can be obtained by forming a mask on an infrared laser ablation layer and thoroughly shutting off oxygen. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a method for producing a high-resolution flexographic printing plate obtained by blocking oxygen during exposure for producing a flexographic printing plate, and a flexographic printing plate obtained by this method.
In this specification, the high-resolution flexographic printing plate is a conventional plate that has a relief dot portion formed flat and has at least an image reproducibility of 70% or more and is further made without an oxygen barrier layer. Compared with the flexographic printing plate, the image reproduction rate is improved by 10% or more. Here, the image reproduction rate refers to the ratio of the relief size actually obtained from the plate-making flexographic resin plate to the image size drawn on the mask forming layer, expressed as a percentage.

  Flexographic printing plates are often used for letterpress printing on soft printed materials such as cardboard, bags, and synthetic resin films. As the plate making method, there are a method for making a plate using a negative film and a method for making a plate directly from digital data (CTP method). In the method of making a plate directly from digital data, the digitalized image data can be corrected on a computer. Therefore, the direct plate-making method has the advantage that it is not necessary to make a negative film again unlike the conventional plate-making method using negative fill, and is widely used.

As this direct plate-making method, there is a method of making a plate by providing a mask forming layer on a photosensitive layer on a support layer of a flexographic resin plate. However, since this method does not have a structure for removing oxygen present on the plate surface during plate making, the curing reaction of the photosensitive layer is inhibited by oxygen present on the plate surface during exposure. Accordingly, the photosensitive layer is not sufficiently cured, and the resolution of the flexographic printing plate is lowered.
In order to solve this problem, a support layer, a photosensitive layer, a barrier layer that protects the photosensitive layer from oxygen, and an infrared laser ablation layer that is substantially opaque to non-infrared are sequentially laminated as a flexographic resin plate. A flexographic resin plate has been proposed. This flexographic resin plate first forms a mask by ablating the infrared laser ablation layer with an infrared laser, then exposes the photosensitive layer through the barrier layer, and further eliminates the inhibition of oxygen curing by the barrier layer. It is exposed to light to produce a printing plate (Patent Document 1). However, in the method for producing a flexographic printing plate using the above-described flexographic resin plate, if the barrier layer is thickened in order to completely block oxygen during exposure, halation of exposure light occurs in the barrier layer at the time of exposure. In many cases, the cured pattern of the adhesive layer was adversely affected and the resolution was lowered. Therefore, the disclosed technique does not sufficiently block oxygen due to the limitation of the thickness of the barrier layer, and as a result, the curing reaction is inhibited by oxygen in the photosensitive layer, and the resolution is sufficiently improved as a flexographic printing plate. There is a problem of not.

International Publication No. 94/03838

  In order to overcome the disadvantages of the conventional flexographic printing plate and the method for producing the same, the present invention provides a method for producing a high-resolution flexographic printing plate in which sufficient oxygen is blocked after forming a mask on the photosensitive layer, and the method is provided. The purpose is to obtain a flexographic printing plate.

  The invention according to claim 1 includes a step of forming a mask on the photosensitive layer using a flexographic resin plate having at least a support layer, a photosensitive layer, and a mask forming layer, and the mask and the photosensitive layer. Flexographic printing obtained by forming an oxygen barrier layer, exposing the entire surface of the flexographic resin plate with non-infrared rays, and removing an uncured photosensitive layer protected by the oxygen barrier layer, mask and mask The present invention relates to a method for producing a high-resolution flexographic printing plate characterized in that the front end portion of the dots of the plate is formed flat.

  The invention according to claim 2 is characterized in that the step of forming an oxygen blocking layer on the mask and the photosensitive layer comprises a composition of an oxygen blocking layer that transmits non-infrared rays and can be removed during development. The method for producing a high-resolution flexographic printing plate according to claim 1, wherein the method is a step of directly coating on the photosensitive layer.

  According to a third aspect of the present invention, in the step of forming an oxygen blocking layer on the mask and the photosensitive layer, an oxygen blocking film that transmits non-infrared rays and can be removed during development is formed by the mask and the photosensitive layer. The method for producing a high-resolution flexographic printing plate according to claim 1, which is a step of coating on a layer.

  The invention according to claim 4 is a flexographic printing plate in which a relief image is formed by being fully exposed through a mask and further developed, and shuts off oxygen around the mask before being fully exposed. Thus, the present invention relates to a high-resolution flexographic printing plate characterized in that the tip of the dot of the flexographic printing plate is formed flat.

  According to the first aspect of the present invention, by providing the step of removing oxygen present around the mask as a method of blocking oxygen, the tip portion of the dot of the obtained flexographic printing plate is formed flat. A method for producing the featured high resolution flexographic printing plate can be constructed.

  According to the second aspect of the present invention, as a method for blocking oxygen, the method includes a step of directly providing an oxygen blocking layer that is transparent to non-infrared and can be removed during development. The method of manufacturing a high-resolution flexographic printing plate can be constructed.

  According to the invention of claim 3, as a method for blocking oxygen, it is coated with an oxygen blocking film that is transparent to non-infrared rays and can be removed at the development stage, and easily blocks oxygen, thereby inhibiting curing by oxygen. The method of manufacturing a high-resolution flexographic printing plate can be constructed.

  According to the invention of claim 4, since the oxygen around the mask is shut off before the flexo resin plate is fully exposed, the flexographic printing plate according to the invention is capable of curing the photosensitive resin layer with oxygen. Therefore, the dot portion of the flexographic printing plate becomes a high-resolution flexographic printing plate formed flat.

It is sectional drawing which shows the manufacturing process of a flexographic printing plate. 2 is a halftone dot photograph of a flexographic printing plate with an oxygen barrier layer according to an example of the present invention. 2 is a halftone dot photograph of a flexographic printing plate without an oxygen barrier layer according to a comparative example of the present invention. It is a halftone dot 3D image of a flexographic printing plate without an oxygen barrier layer according to an embodiment of the present invention. It is a halftone dot 3D image of a flexographic printing plate with an oxygen barrier layer according to a comparative example of the present invention.

  Hereinafter, the flexographic printing plate and the manufacturing method thereof according to the present invention will be described in detail.

FIG. 1 shows a manufacturing process of a flexographic printing plate according to the present invention.
In the figure, A is a flexographic resin plate used for production of a high-resolution flexographic printing plate according to the present invention. The flexographic resin plate A has a support layer 1, a photosensitive layer 2 that is cured by non-infrared rays, and a mask forming layer 3 that is opaque to actinic radiation and can be ablated when exposed to infrared laser light.
In the present invention, the support layer 1 may be any material that can be used for a normal flexographic printing plate that satisfies the mechanical strength required for printing conditions. The photosensitive layer 2 is a photosensitive resin composition suitable for flexographic printing containing an initiator that is sensitive to non-infrared rays, and may be anything that can be cured by non-infrared rays. The mask forming layer 3 can be ablated by exposure with infrared laser light.
The flexographic resin plate A used in the present invention is composed of the support layer 1, the photosensitive layer 2, and the mask forming layer 3. However, the flexographic resin plate A is not limited to the above-described configuration, and may be any suitable for flexographic printing. Good.

In the first step of the manufacturing method according to the present invention, a mask is first formed by ablating the mask forming layer 3 of the flexographic resin plate A with an infrared laser. Since this mask is opaque to non-infrared rays, when the entire surface is exposed to non-infrared rays, the mask serves to protect the photosensitive layer 2 from exposure to non-infrared rays. Various types of infrared lasers can be used as the infrared laser used at this time.

In the second stage of the manufacturing method according to the present invention, in order to prevent the inhibition of curing of the photosensitive layer 2 due to oxygen around the mask, an oxygen blocking layer 4 is formed on the mask and the photosensitive layer 2 after the mask is formed. . The oxygen blocking layer 4 blocks oxygen on the mask and the photosensitive layer 2, minimizes the influence of oxygen during exposure, and leads to a curing reaction of the photosensitive layer 2 without oxygen inhibition.

  The oxygen blocking layer 4 used in the present invention is not particularly limited as long as it has low oxygen permeability and transmits exposure light such as non-infrared rays. As a method of providing the oxygen blocking layer 4, a method in which a polymer layer is directly applied to the mask forming layer 3 of the flexographic resin plate A by solution casting, or a film having a polymer layer is laminated on the mask forming layer 3 of the flexographic resin plate A. And a method of applying a liquid resin having a high viscosity and a low volatility on the mask forming layer 3 of the flexographic resin plate A is not limited to these methods. Any method may be used as long as the oxygen blocking layer 4 can be provided on the mask forming layer 3. However, as a suitable method, when handling etc. are considered, the method of providing the oxygen barrier layer 4 by the method of apply | coating a polymer layer directly and the method of laminating | stacking the film which has a polymer layer is mentioned.

In the present invention, a direct coating method is desirable as a method of coating the oxygen blocking layer 4 on the mask forming layer 3.
Examples of the direct application method include, but are not limited to, a method of applying the oxygen blocking layer 4 composition by spin coating, bar coating, roll coating, spray coating, or the like.
As a method other than the direct application method, a film coated with the composition of the oxygen blocking layer 4 is prepared, and after the mask is formed by a method such as lamination, the oxygen blocking layer 4 is transferred onto the mask and the photosensitive layer 2 Is mentioned. The oxygen barrier layer 4 composition used in this method needs to be transparent to non-infrared and removable during development.
When the oxygen blocking layer 4 is provided on the mask and the photosensitive layer 2 by transfer after the mask is formed, a protective film may be provided in consideration of prevention of contamination of the oxygen blocking layer 4. Thereby, the protective film is peeled off when the oxygen blocking layer 4 is provided, and the oxygen blocking layer 4 can be easily provided on the mask and the photosensitive layer 2 by a laminator. Moreover, it can be stored until use by providing a protective layer.

The material of the oxygen blocking layer 4 according to the present invention is preferably a material that is transparent to non-infrared rays, has a gas barrier property, and does not chemically bond to the photosensitive layer 2 composition. The oxygen blocking layer 4 can be used as long as it has non-infrared transparency, but a material that transmits 90% or more of the wavelength light that is sensitive to the photosensitive layer 2 is particularly desirable. Suitable materials for the oxygen barrier layer 4 include polyamide polymers, polyvinyl alcohol (PVA), polyvinyl butyral (PVB), cellulose polymers such as hydroxyalkyl cellulose and ethyl cellulose, polyvinyl acetate, polyester, ethylene-vinyl acetate copolymer, Although polyethylene, polyacrylic resin, polycarbonate, polybutadiene, etc. are mentioned, it is not limited to these materials. Further, two or more of these polymers can be mixed and used. Particularly preferably, a polyamide polymer, polyvinyl butyral (PVB), hydroxyalkyl cellulose, or ethyl cellulose may be used alone or in combination. The degree of polymerization of the polyamide-based polymer and the polyvinyl butyral may be appropriately selected according to the coating method of the oxygen blocking layer 4, and is preferably a degree of polymerization of 3000 to 500, and more preferably a degree of polymerization of 2000 to 1000.

The oxygen blocking layer 4 is necessary only at the time of exposure. However, in view of preventing the inhibition of curing of the photosensitive layer 2 by oxygen, the thickness of the oxygen blocking layer 4 is preferably as thick as possible. However, when the thickness of the oxygen blocking layer 4 is increased, the non-infrared transmittance is deteriorated, it is necessary to increase the exposure time, and halation of the exposure light beam in the oxygen blocking layer 4 occurs. Decreasing the resolution of the cured pattern is a problem.
In the present invention, the thickness of the oxygen blocking layer 4 needs to be suppressed to a certain thickness. As thickness of the oxygen interruption | blocking layer 4 which concerns on this invention, 1.0-10.0 micrometers is preferable, More preferably, it is 2.0-5.0 micrometers. Compared with a general barrier layer, the oxygen barrier layer 4 according to the present invention can have a thickness more than doubled. Accordingly, it is possible to completely suppress the inhibition of curing of the photosensitive layer 2 by oxygen while preventing halation of the exposure light beam in the oxygen blocking layer 4. This oxygen barrier layer 4 is removed after exposure. Therefore, the oxygen blocking layer 4 of the present invention may be provided by any method as long as it is provided on the mask and the photosensitive layer 2.

In the third stage of the production method according to the present invention, the entire surface of the flexographic resin plate A provided with the oxygen blocking layer 4 is exposed with non-infrared rays. The photosensitive layer 2 is sensitive to non-infrared rays and is cured by the exposure. Therefore, the portion of the photosensitive layer 2 that is not protected by the mask can be cured. However, the portion that is protected by the mask does not pass through non-infrared rays and therefore does not cure.

The fourth stage of the manufacturing method according to the present invention is a stage for cleaning the flexographic resin plate A after the entire exposure. In the cleaning step, not only the oxygen blocking layer 4 and the mask but also the uncured photosensitive layer 2 protected by the mask is removed. Accordingly, a relief as shown in FIG. 1 is formed on the support layer 1 to produce a high-resolution flexographic printing plate according to the present invention.

The flexographic printing plate according to the present invention is a high-resolution flexographic printing plate in which the dot tip portion is formed flat and the image reproduction rate is improved by 10% or more compared to the conventional one.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the examples. An example of conditions for producing the oxygen barrier layer is shown below.

Example 1
15 g of polyamide resin TXS-223 (Fuji Kasei Kogyo Co., Ltd.) was dissolved in 85 g of solvent (xylene: n-butanol = 1: 1) to prepare a 15% solution. Next, a mask was formed on the photosensitive layer of Dupont flexo resin plate Cyrel45DPI (for CTP, 1.14 mm) using infrared ablation. Furthermore, the adjusted 15% polyamide solution was applied onto the mask and the photosensitive layer by an auto film coater (manufactured by Tester Sangyo Co., Ltd.) to form an oxygen barrier layer. The flexo resin plate coated with the polyamide solution was placed in a constant temperature bath at 100 ° C. for 5 minutes to remove the solvent, and allowed to stand until the temperature of the obtained flexo resin plate for CTP with an oxygen blocking layer was lowered to room temperature.
The obtained flexographic resin plate for CTP with an oxygen barrier layer was subjected to plate making under the following conditions to produce a flexographic printing plate of an example according to the present invention. As a comparative example, a flexographic printing plate for CTP without an oxygen barrier layer was prepared under the following conditions to prepare a flexographic printing plate.

(Prepress conditions)
Used exposure machine: A2 size exposure machine light source lamp manufactured by JEOL Ltd .: PHILIPS-10R40W
Back exposure: 10 seconds
Main exposure: 10 minutes Cleaning solution: Lunasolve II (25.2 ° C)
Washing machine: Rotary washing machine (washing time: 3 minutes)
Drying time: 1 hour (60 ° C hot air dryer)
Surface treatment time: 10 minutes after exposure time: 10 minutes

FIGS. 2 and 3 are photographs in which 100 Line 2% halftone dot portions of the flexographic printing plate with an oxygen barrier layer and the flexographic printing plate without an oxygen barrier layer after plate making were observed using a microscope (manufactured by Keyence Corporation). In addition, FIGS. 4 and 5 show 3D composite images of the observed halftone dot portions using the microscope function.
2 and 3, the dot portion of the flexographic printing plate having no oxygen blocking layer of the comparative example shown in FIG. 3 is tapered, but the flexographic printing plate with the oxygen blocking layer according to the present invention shown in FIG. 2 is used. It can be seen that the tip of the dot portion is clearly flat. The reason that the tip of the dot portion of the flexographic printing plate having no oxygen blocking layer in FIG. 3 is tapered is considered to be that the photosensitive layer is inhibited from being cured by oxygen during exposure.
Further, when comparing FIG. 4 and FIG. 5, the tip of the dot portion of the flexographic printing plate having no oxygen blocking layer of the comparative example shown in FIG. 5 is not only rounded but also the entire dot portion is rounded. Can be seen. On the other hand, it is shown that the tip of the dot portion of the flexographic printing plate with an oxygen barrier layer according to the present invention shown in FIG. 4 is formed flat and the entire dot portion also rises sharply.
Further, the tip diameter of the dot portion of the flexographic printing plate without the oxygen blocking layer is 0.03 mm to 0.04 mm, and the tip diameter of the dot portion of the flexographic printing plate with the oxygen blocking layer is 0.07 to 0.08 mm. ing.

  Therefore, a conventional CTP flexo resin is provided by providing a polymer layer having an oxygen blocking effect on the carbon layer of the CTP flexo resin plate in which an image is first drawn on the carbon layer (mask forming layer) using infrared ablation. It was shown that the dot tip can be prevented from tapering due to the inhibition of curing of the photosensitive layer at the time of exposure as seen in the plate, and a high-resolution flexographic printing plate can be produced.

Example 2
15 g of polyamide resin TXS-223 (Fuji Kasei Kogyo Co., Ltd.) was dissolved in 85 g of solvent (xylene: n-butanol = 1: 1) to prepare a 15% solution. Next, an auto film coater (manufactured by Tester Sangyo Co., Ltd.) is formed on the mask forming layer of flexographic resin plate FAH114D (manufactured by Fint, CTP, 1.14 mm) having an image drawn on the mask forming layer using infrared ablation. ) Was used to apply the adjusted 15% polyamide solution to form an oxygen barrier layer. The flexo resin plate coated with the polyamide solution was placed in a constant temperature bath at 80 ° C. for 5 minutes to remove the solvent, and allowed to stand until the temperature of the obtained flexo resin plate for CTP with an oxygen barrier layer dropped to room temperature.
The obtained flexographic resin plate for CTP with an oxygen barrier layer was subjected to plate making under the following conditions to produce a flexographic printing plate of an example according to the present invention. As a comparative example, a flexographic printing plate for CTP without an oxygen barrier layer was prepared under the following conditions to prepare a flexographic printing plate.

(Prepress conditions)
Used exposure machine: A2 size exposure machine light source lamp manufactured by JEOL Ltd .: PHILIPS-10R40W
Back exposure: 10 seconds
Main exposure: 10 minutes Cleaning solution: Lunasolve II (28.6 ° C)
Washing machine: Rotary washing machine (washing time: 3 minutes)
Drying time: 1 hour (60 ° C hot air dryer)
Surface treatment time: 10 minutes after exposure time: 10 minutes

Observe and measure the relief of each of the flexographic printing plate with oxygen barrier layer and the flexographic printing plate without oxygen barrier layer after making a plate using a microscope, and determine the image size drawn on the mask forming layer and the actually obtained relief size. Compared.
The size of the image drawn on the mask forming layer of the CTP flexo resin plate by infrared laser ablation was compared with the size of various reliefs actually obtained by producing the FAH114D with an oxygen barrier layer. Table 1 shows the measurement results. Shown in

The size of the image drawn on the mask forming layer of the CTP flexographic resin plate by infrared laser ablation was compared with the size of various reliefs actually obtained by producing the flexographic resin plate FAH114D without an oxygen blocking layer. Table 2 shows the measurement results. Shown in

  From the above results, the difference between the image size of the UV transmitting portion drawn on the mask forming layer and the size of the relief obtained by actual plate making is clearly smaller in the flexographic printing plate provided with the oxygen blocking layer. It has been shown that flexographic printing plates with a barrier layer clearly have a higher image size recall.

  The present invention relates to a high-resolution flexographic printing plate and a method for producing the same, and the flexographic printing plate and the method for producing the same according to the present invention can be widely used in the printing industry.

DESCRIPTION OF SYMBOLS 1 ... Support body layer 2 ... Photosensitive layer 3 ... Mask formation layer 4 ... Oxygen blocking layer

Claims (4)

A step of forming a mask on the photosensitive layer using a flexographic resin plate having at least a support layer, a photosensitive layer, and a mask forming layer;
Forming an oxygen barrier layer on the mask and the photosensitive layer;
Exposing the entire surface of the flexographic resin plate with non-infrared rays; and
The oxygen-blocking layer, the mask, and the tip of the dot of the flexographic printing plate obtained by removing the uncured photosensitive layer protected by the mask are formed flat. Production method. The step of forming an oxygen blocking layer on the mask and the photosensitive layer directly applies a composition of an oxygen blocking layer that transmits non-infrared rays and can be removed during development onto the mask and the photosensitive layer. The method for producing a high-resolution flexographic printing plate according to claim 1, wherein The step of forming an oxygen blocking layer on the mask and the photosensitive layer is a step of covering the mask and the photosensitive layer with an oxygen blocking film that transmits non-infrared rays and can be removed during development. The method for producing a high-resolution flexographic printing plate according to claim 1. A flexographic printing plate in which a relief image is formed by being exposed through a mask and further developed,
By blocking oxygen around the mask before full exposure,
A high-resolution flexographic printing plate characterized in that the tip of the dot of the flexographic printing plate is formed flat.

Images