JPH0743532B2 - Partially multilayered printing plate and manufacturing method thereof - Google Patents

Description

TECHNICAL FIELD The present invention relates to a partially multilayered printing plate and a method for producing the same. More specifically, the present invention is particularly suitable for printing corrugated cardboard sheets, and is also useful for printing newspapers, magazines, books, etc., and a partially multilayered printing plate having excellent printability It relates to a method of manufacturing well.

2. Description of the Related Art In recent years, photosensitive resin plates have been widely used in many relief printing fields. This photosensitive resin plate is usually obtained by subjecting a single photosensitive resin layer containing one type of photosensitive resin composition to image forming exposure and development treatment, but recently two types of photosensitive resin composition were used. Using a multi-layer plate (see, for example, JP-A-54-9
2402) has been developed and commercialized, and is being used for printing corrugated cardboard sheets, newspapers, magazines, books, etc., as it has excellent printability.

The two types of photosensitive resin compositions in this multi-layer plate have a positive correlation with the photosensitivity such as the photosensitivity and the photosensitivity wavelength range, and the hardness after photocuring, compression modulus, Young's modulus, tensile modulus, etc. Any one of the mechanical properties
One characteristic or both characteristics are different.

An example of such a multi-layered printing plate will be described with reference to the accompanying drawings. FIG. 1 is a cross-sectional view of an image area of the support 1
A relief 2 and a non-image area 3 in which the hardness of the relief upper portion (cap portion) A and the hardness of the relief lower portion (base portion) B differ from each other are provided on the top. If the hardness of the cap portion, that is, the portion A that comes into contact with the substrate through the ink is higher than the hardness of the base portion B, the portion B bears most of the relief distortion due to the printing pressure during printing. The deformation of the portion can be minimized, and the thickening of the printed surface can be reduced. This is because the relief has a hardness difference and is provided with a cushioning effect due to the multilayer structure.

On the other hand, FIG. 2 is a sectional view of an image area of another example, in which the multilayer printing plate shown in FIG.
The sensitivity 2 of the photosensitive resin composition and the sensitivity of the photosensitive resin composition of the base portion B are different from each other, and the relief 2 and the non-image area 3 are provided. The resin composition has a longer induction period than that of the base portion B, and the gradient l / Q (or l) of the cured thickness (l) with respect to the light amount (Q) [irradiation time (t) when the light source intensity is constant].
/ t) shows the relief shape when it is set to be large. In such a multi-layered printing plate, it is possible to prevent white areas and halftone dot high density areas from being filled up by overexposure, and it is possible to form reliefs of extremely small highlight halftone dots.

In these multi-layered printing plates (capped plates), the one shown in FIG. 1 is called a hardness difference cap plate, and the one shown in FIG. 2 is called a sensitivity difference cap plate.・ The sensitivity difference cap version is also in practical use.

When making such a multi-layered printing plate, in the printing plate manufacturing technology using the photosensitive resin composition so far, in order to attach the capping device in combination with the device for manufacturing a conventional single-layer printing plate. , The whole edition was inevitably multi-layered. That is, in the conventional printing plate manufacturing technology, it was not possible to manufacture either a single-layer printing plate as a whole plate or a multilayer printing plate as a whole plate with a single plate-making apparatus.

By the way, in actual printing, there are many cases where large solid portions, fine characters, and fine line portions are mixed. In such a case, a plate having a lower hardness is desired for the large solid portions, while fine letters and fine line portions are more preferable. A hardness difference cap plate having a high hardness and a cushioning effect is desired, but it has been impossible to simultaneously realize a plate having such contradictory properties with the conventional technology. Therefore, the negative film has to be divided into two parts, and the plate making apparatus conditions around the device have to be changed so that the single-layer plate and the multi-layer plate have to be separately prepared, resulting in a long plate-making time, As the amount of materials consumed becomes large, or the plates made separately are laid out according to the original layout and laid out so that the dimensions are not mistaken, the entire work becomes extremely complicated, which leads to an undesirable situation. The printing plate was inevitably expensive.

Problems to be Solved by the Invention Under the circumstances, the present invention provides a partially multi-layered printing plate having excellent printability and having the advantages of a single-layer printing plate and a multi-layered printing plate. It was made for the purpose.

Means for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the present inventors formed a multilayer structure composed of a plurality of photosensitive resin cured layers having different physical properties in a desired image area. It was found that the object can be achieved by forming a single layer composed of one type of photosensitive resin cured layer in the other image area, and based on this finding, the present invention was completed. Ivy.

That is, according to the present invention, a part of the image area has a multi-layer structure composed of a plurality of photosensitive resin cured layers having different physical properties, particularly hardness, compression modulus, Young's modulus and other mechanical properties, and the remaining part is one type of photosensitive material. It is intended to provide a partially multilayered printing plate having a single-layer structure composed of a cured resin layer.

This partially multi-layered printing plate forms, for example, a laminated portion of a plurality of photosensitive resins having different photosensitivity or a plurality of photosensitive resins having different physical properties such as hardness after curing in a part of the image forming area on the support. At the same time, a single layer of one kind of photosensitive resin is formed on the remaining portion, and then exposure is carried out for image formation, and then development processing is carried out, whereby it can be manufactured.

When a difference in hardness after photocuring is provided in the printing plate of the present invention, the difference in hardness is 5 degrees or more, preferably 10 degrees or more. The hardness means an initial value of measurement, that is, an instantaneous value.

When photosensitive resins having different photosensitivity are used for producing the printing plate of the present invention, the photosensitivity when measured under the same measurement conditions is T _C / T _B ≧ 1.1 or γ _C / γ _B ≧ 1.1. Is more preferable, and T _C / T _B ≧ 1.5 or γ _C / γ _B ≧ 1.5 is more preferable because the image reproducibility is further improved.

Note that T _C , T _B , γ _C and γ _B mean the following.

T _C : Curing induction period of the cap portion photosensitive resin composition T _B : Curing induction period of the base portion photosensitive resin composition γ _C : For the cap portion photosensitive resin composition, t ₁ , t ₂
Value obtained from the following formula from the cured thicknesses l ₁ and l ₂ after irradiation for a certain period of time γ _B : A value obtained for the base portion photosensitive resin composition in the same manner as in the above γ _C. Next, according to the attached drawings, the partially multilayered printing plate of the present invention is produced using a molding / exposure device. Method will be described. FIG. 3 is a cross-sectional view showing the steps of the exposure treatment. When the image forming exposure is performed from the lower side of the glass plate (A), the photosensitive resin composition is kept constant during the production of the single-layer printing plate. On the transparent glass plate 11 in the exposure zone for forming into a thickness, the image carrier 12 such as a negative film is arranged, and if desired, the cover film 13 is adhered and laminated thereon, and on the other hand, the image forming exposure is performed from above. In the case of (B), it is desired to arrange a support such as a metal base sheet or a plastic base film on a transparent glass plate or a metal plate or a rigid plastic plate in the exposure zone, and to partially form a multilayer. On two parallel sides around the image,
A spacer having a predetermined thickness is arranged, and a photosensitive resin composition used as a relief layer which comes into contact with a printing ink in the case of (A) is supplied in the immediate vicinity or in the vicinity of the center of the image area. A metal or plastic square plate or bar that can function as a doctor is placed on the spacer, and the spacer is slid on the spacer so as to cover the image portion, and the desired image portion in which the photosensitive resin composition is multilayered is formed. Squeegee to the specified thickness only in the area. At this time, if a squeegee photosensitive resin composition may be attached to an image area that does not require multi-layering, a protective material such as a protective film or a protective sheet may be previously attached to the image area before the squeegee. It is preferred to cover and remove it after the squeegee. When such a protection operation is not performed, it is necessary to wipe off the photosensitive resin composition attached to the unnecessary image area after the squeegee with a waste cloth or the like. Then, the photosensitive resin composition for the lower part of the relief layer and for the single layer may be squeegeeed over the entire surface by a usual method.

On the other hand, in the case of (B), the photosensitive resin composition is divided into one for the relief layer lower part and one for the relief layer upper part (the side in contact with the printing ink) and for the single layer, which corresponds to the lower part of the relief layer first. The photosensitive resin composition may be squeegeeed by the above method, and then the photosensitive resin compositions for the single layer and the upper portion of the relief layer may be squeegeeed by a usual molding method.

Incidentally, the doctor may be operated by hand, or when using a device having a carriage in which a doctor is arranged for plate making of a single layer plate, a photosensitive resin composition for a multilayer plate is provided on the squeegee tip side of the carriage. Place a doctor to squeegee,
Thereby, the same operation as described above may be performed.

The photosensitive resin composition used in the present invention is not particularly limited, and various known photosensitive resin compositions used for printing plates (Japanese Patent Publication No. Sho 43-19125, No. 45).
-3915, 45-23165, 45-25829,
46-29525 publication, 48-43126 publication, 46-9284 publication, 52-7363 publication, 53-2082 publication, 53-35481 publication, JP-A-56-120718 publication. , U.S. Pat. No. 3,801,328, West German Patent No. 2,215,090, and French Patent No. 2,103,825). Of these photosensitive resin compositions, those that are liquid at room temperature can be used as they are, but those that are solid at room temperature can be used by dissolving them in a suitable solvent and evaporating the solvent after molding. Good.

Specific examples of the photosensitive resin composition include a composition containing a prepolymer having an ethylenically unsaturated group and a photopolymerization initiator as main components, and optionally an ethylenically unsaturated monomer and a thermal polymerization inhibitor added. Alternatively, various polymers such as acrylic resin, polyamide, polyurethane, polyvinyl alcohol and polystyrene are dissolved and mixed in an ethylenically unsaturated monomer, and a photopolymerization initiator is added.

The prepolymer having an ethylenically unsaturated group, for example, unsaturated polyester, unsaturated polyurethane,
Oligoester acrylates, oligoester methacrylates, unsaturated polyamides, unsaturated polyimides, unsaturated polyethers, unsaturated polyacrylates, unsaturated polymethacrylates and various modifications thereof, various rubber compounds having carbon-carbon double bonds, etc. Can be mentioned. As these prepolymers, those having an average molecular weight of substantially 500 or more are usually used.

Specific examples of such prepolymers include unsaturated polyesters and alkyds such as maleic acid,
Unsaturated dibasic acids such as fumaric acid and itaconic acid or acid anhydrides thereof and ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol,
Glycerin, trimethylolpropane, pentaerythritol, 1,4-polybutadiene having a terminal hydroxyl group, polyester with a polyhydric alcohol such as hydrogenated or non-hydrogenated 1,2-polybutadiene-acrylonitrile copolymer, and one of the acid components Polyester in which a part is replaced with a saturated polybasic acid such as succinic acid, adipic acid, phthalic acid, isophthalic acid, phthalic anhydride, trimellitic acid, or a polyester modified with a drying oil fatty acid or a semi-drying oil fatty acid, is unsaturated. As the polyurethane, a compound obtained by introducing an addition-polymerizable unsaturated group using a terminal isocyanate group or a hydroxyl group of a compound linked via a urethane group derived from a polyisocyanate and a polyol having two or more terminal hydroxyl groups, for example, The above-mentioned polyhydric alcohol, polyester polyol, 1,4-polybutadiene having a polyol terminal hydroxyl group such as a polyether polyol, hydrogenated or non-hydrogenated 1,2-polybutadiene, butadiene-styrene copolymer, butadiene-acrylonitrile copolymer and toluylene diisocyanate, diphenylmethane-4 , 4'-diisocyanate, those introduced with an unsaturated group by utilizing the reactivity of the terminal isocyanate or hydroxyl group of polyurethane with polyisocyanate such as hexamethylene diisocyanate, or the above-mentioned unsaturated carboxylic acid or its ester hydroxyl group, A compound having an unsaturated group introduced by reacting a compound having active hydrogen such as a carboxyl group or an amino group with isocyanate, or an unsaturated group introduced by reacting a compound having a carboxyl group with a hydroxyl group, or the above unsaturated polyester To And compounds linked by polyisocyanate are exemplified. Further, as the oligoester acrylates, acrylic acid or methacrylic acid is allowed to coexist in the ester reaction system of a polybasic acid and a polyhydric alcohol, and co-condensed to adjust each molar ratio to a molecular weight of about 200 to 5000, For example, an acrylic acid or an acrylic acid is added to an ester reaction system of polyhydric alcohol such as adipic acid, phthalic acid, isophthalic acid or acid anhydride and ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, glycerin, trimethylolpropane, pentaerythritol, etc. Condensed with methacrylic acid in the presence of condensation, epoxy acrylates such as polyhydric alcohols, polyhydric phenols or polyphenols, and compounds having an epoxy group obtained by polycondensation reaction of epichlorohydrin or alkylene oxide with acrylic acid Or an ester with methacrylic acid, a polymer compound having an addition-polymerizable carbon-carbon double bond in the side chain, for example, polyvinyl alcohol, a polymer compound having a hydroxyl group such as cellulose, and an unsaturated carboxylic acid or an acid anhydride thereof. A compound obtained by reacting with, a polymer compound having a carboxyl group such as a polymer or copolymer of acrylic acid or methacrylic acid, and an unsaturated alcohol,
Ester-bonded glycidyl acrylate or methacrylate, a reaction product of a copolymer containing maleic anhydride and allyl alcohol, hydroxyalkyl acrylate or methacrylate, and the like, a copolymer containing glycidyl acrylate or methacrylate as a copolymerization component. Examples thereof include a reaction product of the combined product and acrylic acid or methacrylic acid. Further, as various rubber compounds, (1) 1,4-polybutadiene, 1,2-polybutadiene, butadiene-styrene copolymer, butadiene-acrylonitrile copolymer, EPDM, (II) water additive of (I) above Examples thereof include an isobutyle-isoprene copolymer, an ethylene-propylene copolymer, and an unsaturated modified rubber obtained by introducing an ethylenically unsaturated group into various rubber compounds represented by (I) by a known technique. The compound (I) can be used as it is, but it is convenient to use various rubber compounds having a terminal functional group in order to introduce the unsaturated group. Further, in the case of a rubber compound having a 1,2-polybutadiene segment, the unsaturated group can be easily introduced by adding maleic anhydride to the compound.

As the ethylenically unsaturated monomer, various known compounds can be used, and examples of such a compound include unsaturated carboxylic acids such as acrylic acid and methacrylic acid or esters thereof such as alkyl- and cyclo- Alkyl-, halogenated alkyl-, alkoxyalkyl-, hydroxyalkyl-, aminoalkyl-, tetrahydrofurfuryl-, allyl-, glycidyl-, benzyl-, phenoxy-acrylates and methacrylates, alkylene glycols, polyoxyalkylene glycol mono or Diacrylates and methacrylates, trimethylolpropane triacrylates and methacrylates, pentaerythritol tetraacrylates and methacrylates, acrylamides, methacrylamides or their derivatives, eg alkyl groups Allyl compounds, such as allyl alcohol, allyl isocyanate, N-substituted or N, N'-substituted acrylamides and methacrylamides, diacetone acrylamides and methacrylamides, N, N'-alkylenebisacrylamides and methacrylamides, which are N-substituted with hydroxyalkyl groups. Other unsaturated compounds such as styrene, vinyltoluene, diallyl phthalate, triallyl cyanurate, maleic acid, maleic anhydride, fumaric acid or esters thereof, such as alkyl, alkyl halides, alkoxyalkyl mono or dimaleates and fumarate. Divinylbenzene, N-
Examples thereof include vinylcarbazole and N-vinylpyrrolidone. Further, a part of these monomers is used as an azide compound such as 4,4'-diazidostilbene, p-phenylene-bisazide, 4,4'-diazidobenzophenone, 4,4'-diazidophenyl. Methane, 4,4'-diazidochalcone, 2,6-di (4'diazidobenzal) -cyclohexanone, 4,4'-diazidostilbene-alpha-carboxylic acid, 4,4'-diazidodiphenyl, 4 Substituted with 4,4'-diazidostilbene-2,2'-sodium disulfonate may also be used.

These monomers are 0-2 with respect to 100 parts by weight of the prepolymer.
It may be added in the range of 00 parts by weight.

On the other hand, various photosensitizers known as photopolymerization initiators, for example, benzoyl, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin butyl ether, benzoin isobutyl ether, 2,2-dihydroxy-2. -Phenylacetophenone, 2,2-dimethoxy-
2-phenylacetophenone, 2,2-diethoxy-2-
Phenylacetophenone, 2,2-diethoxyacetophenone, benzophenone, 4,4'-bisdialkylaminobenzophenone, 4-dimethylaminobenzoic acid, 4-dimethylaminobenzoic acid alkyl ester, 2-ethylanthraquinone , Xanthone, thioxanthone, 2-chlorothioxanthone and the like can be used. These photosensitizers are usually used in the range of 0.001 to 10% by weight based on the composition.

Further, as the thermal polymerization inhibitor, for example, hydroquinone,
Mono-tert-butyl hydroquinone, benzoquinone, 2,5-
Diphenyl-p-benzoquinone, picric acid, di-p-
Fluorophenylamine, p-methoxyphenol, 2,
6-di-tert-butyl-p-cresol and the like can be mentioned. These thermal polymerization inhibitors are for preventing thermal polymerization reaction (dark reaction), and therefore, the addition amount of the thermal polymerization inhibitor is based on the total amount of the prepolymer and the monomer. It is preferable to select in the range of 0.005 to 5% by weight.

As other photopolymerizable composition, for example, a composition comprising a compound that releases a Lewis acid by light and a compound that undergoes ionic ring-opening polymerization with a Lewis acid such as an oxirane-containing compound (Japanese Patent Publication No. 52-14277). JP-B-52-14278), compositions utilizing the photoaddition reaction of polyene and polythiol (JP-B-46-29525), and the like.

In the present invention, which design has a multi-layered structure mainly depends on the type of design, but its applicable range varies depending on printing conditions and required print quality. Therefore, the area ratio of the multilayer structure is partially different depending on the design, but the present invention can be applied as long as the fine pattern and the solid equivalent pattern coexist. An example of a pattern that preferably has a multilayer structure is a fine wire with a line width of several mm or less or a diameter of several mm.
The following points, a fine pattern including a character composed of them, a halftone dot image, and a pattern in which the fine pattern in the solid equivalent portion is expressed in white can be mentioned.

In the present invention, the photosensitivity of the photosensitive resin composition can be measured as follows.

(1) Preparation of test piece A photopolymerizable layer having a width of 15 cm, a length of 3 cm and a thickness of 4 mm is prepared on a support having an adhesive layer and transparent to active light. When the photopolymerizable layer is in a liquid state, a rubber spacer having a thickness of 4 mm and having the above-mentioned dimensions hollowed out is placed on a plate glass having a thickness of 5 mm, and a liquid photosensitive resin is poured into the spacer to separate it.
Prepare by covering with 5 mm thick glass plate.

On the other hand, in the case where the photopolymerizable layer is in a solid state, a material having a certain thickness is preliminarily formed on the support by using a hot press or an extrusion molding method, and after being cut with a cutter knife or the like into a size of 18 × 3 cm, Scissors with a glass plate as in the case of liquid,
Prepare as a test piece.

(2) Light source As a light source, a 2KW ultra-high pressure mercury lamp (Oak Seisakusho,
Product name: Jetlight) or 20W chemical lamp (product name: FLR-20BL, manufactured by Mitsubishi Electric Corporation) arranged in parallel so that the light source illuminance is uniform, but the latter one is used from the viewpoint of light source stability. Is convenient.

The light source is arranged in a position to illuminate the lower side, and the plate glass having the thickness of 5 mm is located on the light source side, and the support having the adhesive layer used to provide the photopolymerizable layer to be measured. UV-3 the body so that the adhesive layer is on the bottom.
5 Place the filter on a UV meter (Oak Seisakusho, trade name UV-M01), and the strength indicated by the UV meter
Determine the height of the light source to be 0.40mW.

(3) Measurement 3 cm with the prepared test piece with the support side up
Five light shielding pieces made of 1 mm thick black rubber plate with a size of 6 cm are arranged side by side from the top of the glass plate to cover the entire test piece. Then sandwich the test piece with a glass plate at the position where the strength was adjusted,
Place with the light shield in place. The stopwatch is started at the same time as removing the first light-shielding piece, and thereafter the light-shielding pieces are sequentially removed at fixed time intervals t. After removing the last light-shielding piece, the light source is turned off after the fixed time t. As a result, 5 t is given to the first small piece, t is given to the last small piece, and the small pieces in between are exposed to light for a fixed time t.

The fixed time t is determined by the sensitivity of the photosensitive resin composition used, and may be set to an appropriate time between 15 seconds and 1 minute.

In the case of a solid photopolymerization layer, the number of light-shielding pieces is increased to create an unexposed area.

(4) Elution, drying, and post-exposure Elution is carried out with an eluent that effectively dissolves or disperses the uncured resin layer. Usually, water, alkaline water or an aqueous surfactant solution is used at 40 ° C. Using a sprayer with a pipe pressure of 2 kg, make the distance from the tip of the nozzle to the test piece 10 cm and wash to avoid uneven washing. For the solvent developing type, a predetermined developing solution may be used. At this time, the test piece is washed from the side opposite to the side irradiated with light, that is, the resin side, and the test is performed for 120 seconds. Then, in a dryer at 60 ℃ 10
After drying for 1 minute, post-exposure is performed from the resin side for 5 minutes under the intensity of 2 mW using the light source.

In the case of the solid photopolymerizable layer, the same operation is carried out with the washing end point at the time when the unexposed portion is completely eluted.

(5) Determination of curing induction period T The thickness of the cured resin layer thus formed on the support is measured with a thickness meter capable of measuring in units of 1/100 mm. The relationship between the thickness of the obtained cured resin layer and the logarithm of the exposure time is represented by a graph, and the curing induction period T is obtained.

(6) Determination of (l ₂ -l ₁ ) / log (t ₂ / t ₁ ) ratio γ From the graph created in (5), it is determined from the slope of the straight line.

EFFECTS OF THE INVENTION According to the method of the present invention, since a partially multilayered printing plate is easily plate-made by a plate-making operation after one exposure step, plate-making cost, plate-making time, and plate-making work are complicated as compared with the conventional plate-making method. And the complexity of mounting work on the plate cylinder are greatly reduced.

Further, in the conventional multi-layered printing plate, plate reproducibility and print quality may be deteriorated, but in the partially multi-layered printing plate of the present invention, since only the image part of the necessary part is multi-layered, Such problems are solved and printability is extremely excellent.

By the way, in printing on a corrugated cardboard sheet, cosmetics have recently been demanded. Therefore, it is more desirable than ever to print more solid ink on the solid portion and print fine letters, fine lines, and halftone dots more sharply. Is getting stronger. In particular, corrugated cardboard sheets have conspicuous irregularities on the surface, which is called a wash board. Therefore, it is necessary to use a printing plate having a lower hardness in order to improve the paste of the ink on the solid portion.
On the contrary, fine lines and fine lines and fine pattern require a printing plate that is harder than usual, but in the case of a corrugated cardboard sheet, the printing pressure is increased in order to eliminate printing unevenness due to the surface irregularities, Even if a single-layer hard plate is used, the thickness at the time of printing becomes large. Therefore, in this part, the relief on the stamp side has high hardness and the lower part of the relief has low hardness. desirable. Of the two types of photosensitive resin compositions used for multilayering in the present invention, a composition exhibiting low hardness is designed to have low hardness so as to satisfy printing of the solid portion, and only fine characters and thin line portions are multilayered. By making the solid portion, the portion for printing the solid portion can be easily made into a partially multi-layered printing plate in which the photosensitive resin composition having a low hardness is used as a single layer, and by using this plate, the solid portion and the details are It is possible to significantly improve the quality of coexisting corrugated board printing. In particular, the partial multi-layered printing plate is suitable for applications where printing accuracy such as physical distribution bar code symbol printing on a corrugated cardboard sheet is required to be extremely high only for this pattern.

Also, for printing printed matter with many blank patterns on the solid part or printed matter with a thin outlined line width, only in such an image area,
By using a low-sensitivity type photosensitive resin composition in the relief layer close to the negative film, by using a relatively high-sensitivity photosensitive resin composition in the lower portion of the relief layer and other image areas,
In addition to the rapid formation of fine print / fine lines and extreme HL, the blank image in the solid area does not become too shallow due to overexposure, and the blank printing line width does not narrow. By using this plate, it is possible to print a solid white image clearly from the printing of extreme HL and details.

EXAMPLES Next, the present invention will be described in more detail with reference to examples.

Example 1 In the state shown in FIG. 3, a negative film is placed on a glass plate, and a cover film is adhered and laminated thereon. Next, as shown in FIG. 4, for the bar code symbol equivalent portion and the address display equivalent portion represented by the fine print in the image of the negative film, 1.
Metal spacers with a thickness of 00 mm and a width of 10 mm were arranged.

Next, a photosensitive resin composition having a hardness of 50 ° H _A (Shore A hardness, instantaneous value, 20 ° C) after photocuring is supplied to one side where a spacer is not arranged, in a thickness of 7 mm, A 5 cm thick metal plate was used as a doctor and slid on the spacer while laminating the composition. This makes the thickness
A 0.5 mm layer of the photosensitive resin composition was formed.

Then, the hardness after photocuring is 35 ° H _A , and a photosensitive resin composition having the same sensitivity as that previously used, by a conventional method, together with a base film having a thickness of 0.1 mm, which is a support, The entire plate was laminated to a thickness of 7 mm. Next, masking exposure, relief exposure and back exposure were carried out by a usual method, and then development, post-exposure and drying were carried out to obtain a partially multilayered printing plate having a total plate thickness of 7 mm.

In this version, the barcode symbol part and the fine address display part had a double-layer structure as designed, and the bold and solid parts had a low-hardness single-layer structure. A sectional view of this partially multilayered printing plate is shown in FIG. In the figure, the solid pattern relief portion D shows a single-layer structure composed of the low-hardness relief portion 4, and the multilayer region C
Shows a two-layer structure composed of a high hardness relief portion (cap portion) 5 and a low hardness relief portion 4. 1 is a support, 3
Is a non-image area.

Using this printing plate, a flexo cardboard printing machine can be used for A-stage C-
Water-based ink (viscosity Zahn Cup #
When printed at a speed of 100 sheets / minute for 4 to 13 seconds, the barcode symbol part and the address display in fine print were very sharp, while the solid part was printed without any ink bleeding.

Example 2 In the molding / exposure apparatus used in Example 1, a negative film having a pattern consisting of a line drawing by a convex line of 100 μm and a white character with a line width of 150 μm in a strip-shaped solid portion was arranged on a glass plate. After that, the cover film was vacuum-bonded onto the cover film.

Then, a spacer having a thickness of 2.0 mm and a width of 10 mm is arranged in parallel with the long side of the solid portion, and then the low sensitivity (the photosensitive resin composition of the single layer / multilayer portion relief lower portion used for the induction period later is used). _A photosensitive resin composition having three times the induction period and the same γ _C and γ _B ) and a hardness of 60 ° H _A after photocuring is required on the other side without a spacer. Quantity supply,
Lamination was performed in the same manner as in Example 1 to form a photosensitive resin composition layer having a thickness of about 1.0 mm.

Next, the hardness after photocuring is 60 ° H _A , and using the high-sensitivity photosensitive resin composition as described above, in the same manner as in the case of making a single-layer printing plate, the whole plate including the base film 3m thick
It was laminated on the entire surface of the negative film so that the film thickness became m. Then, back exposure and relief exposure were performed, and further development, post-exposure in water, and drying were performed by a conventional method to obtain a partially multilayered 3 mm plate. A schematic sectional view of this partially multilayered printing plate is shown in FIG. In the figure, the thin line portion E shows a single-layer structure composed of the relief portion 7 obtained from the high-sensitivity photosensitive resin composition, and the solid white portion F represents the relief portion (capping) obtained from the low-sensitivity photosensitive resin composition. Part) 6 and a relief part 7 obtained from the high-sensitivity photosensitive resin composition.

This plate was mounted on a flexographic rotary press and printed on kraft paper with a water-based ink (15 seconds with Zahn Cup # 4) at a speed of 130 m / min.
It was printed sharply, and the solid ink portion of the white solid part had a very good solid ink paste, and there was no deviation of white characters, and a high-quality printed matter was obtained which was reproducible with sticking.

[Brief description of drawings]

1 and 2 are cross-sectional views of reliefs of a conventional hardness-difference cap plate and a sensitivity-difference cap plate, respectively, and FIG. 3 is an example of a process for making a partially multilayered printing plate of the present invention. FIG. 4 is a plan view showing a state when a layer of a photosensitive resin composition is provided, and FIGS. 5 and 6 are sectional views of different examples of the partially multilayered printing plate of the present invention. In the figure, reference numeral 1 is a support, 3 is a non-image area, 4 is a low hardness relief portion, 5 is a high hardness relief portion, 6 is a relief portion obtained from a low sensitivity photosensitive resin composition, and 7 is The relief portion obtained from the high-sensitivity photosensitive resin composition, C is a multi-layered area, D is a solid pattern relief portion, E is a thin line portion, and F is a white solid portion (multi-layered area).

Claims (3)

[Claims] 1. An image area having a multi-layer structure composed of a plurality of photosensitive resin cured layers having different physical properties, and the remaining part having a single-layer structure composed of one photosensitive resin cured layer. Partial multi-layer printing plate. 2. A laminated part of a plurality of photosensitive resins having different photosensitivity is formed in a part of the image forming area on the support, and a single layer of one kind of photosensitive resin is formed in the remaining part. A method for producing a partially multi-layered printing plate, which comprises exposing to light for image formation and then developing. 3. A layered portion of a plurality of photosensitive resins which give different physical properties after curing is formed in a part of the image forming area on the support, and a single layer of one kind of photosensitive resin is formed in the remaining portion. The method for producing a partially multi-layered printing plate, comprising the steps of: forming an image, exposing it to image formation, and then developing it.