JPS6314339B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel photosensitive resin composition for printing plates, and in particular to a photosensitive polyamide resin composition suitable for producing flexible printing plates and printing plates with little incurl. .

In order to obtain a photosensitive polyamide resin composition that gives a flexible relief image, a system using a soft polyamide resin is generally considered. For example, a flexographic printing plate whose resin component is an aldehyde-modified polyamide is known (Tokuko Sho 50−32647).

This aldehyde-modified polyamide is obtained by reacting an aldehyde directly or in the presence of an alcohol or mercaptan with a polyamide resin.
However, since the aldehyde-modified polyamide obtained in this way is generally used as a crosslinking resin, it tends to undergo a crosslinking reaction by itself, and may be partially damaged during the printing plate manufacturing process or the photosensitive resin composition preparation process. Crosslinking occurs, and when this is made into a photosensitive sheet for printing plate production, for example, the formation of insoluble portions in the development washout process during printing plate production, insufficient white area depth in the printing plate, and aging of the photosensitive plate may occur. The problem is that it is easy.

The present inventors conducted intensive studies to develop a photosensitive polyamide resin composition that provides a flexible relief image free from such problems. As a result, the present inventors added and modified polyamide with ethylene oxide or its substituted product as a resin component. The inventors have discovered that the modified polyamide obtained by this method is suitable for the purpose, and have arrived at the present invention.

That is, the present invention is a photosensitive polyamide resin composition comprising a polyamide having a bond represented by the following general formula as a resin component, a photopolymerizable monomer, and a photopolymerization initiator.

(n is 0 or an integer of 1 to 10, R is H, alkyl, haloalkyl, or aryl) The photosensitive polyamide resin composition of the present invention has excellent compatibility of constituent components, good light transmittance, sensitivity, and relief. Good depth, image reproducibility and storage stability.
It has features such as a fast development speed and a printing plate with particularly excellent flexibility and rubber elasticity.

The polyamide used as the resin component of the photosensitive polyamide resin composition of the present invention is a modified polyamide having an N-substituted amide bond represented by the above general formula in the molecule.

Such a modified polyamide can be obtained by, for example, being modified with ethylene oxide or a derivative thereof. Such modified polyamides can be produced, for example, by heat treating the polyamides in liquid ethylene oxide.

Polyamide is suspended in an inert solvent such as decalin or tetrahydronaphthalene, and ethylene oxide is introduced and reacted with stirring while heating.

It can be obtained by a method such as heating and stirring polyamide in ethylene carbonate.

The modified polyamide used in the present invention has an N-substituted amide bond represented by the above general formula in its molecule, and some of the hydrogen atoms of the amide bond are replaced depending on the conditions during modification. It is presumed that as a result, the hydrogen bonds are weakened and the modified polyamide resin becomes flexible or elastic.

Note that modified polyamides produced by a special method for producing modified polyamides, such as a method utilizing a reaction between an oxyethylated amine and an ester, can also be used in the present invention.

The polyamide used for the modification of the present invention includes dibasic fatty acids, diamines, ω-amino acids,
It is a linear polyamide synthesized from lactam or a derivative thereof by a known method, and copolymerized polyamide is particularly preferably used. Typical examples of these polymerized polyamides are nylon 6/66, 6/66/610, 6/66/610/612, 6/
N,N'-bis(aminopropyl)piperazine
Examples include 6,6/66/P.aminocyclohexylmethane. Furthermore, the term "modified polyamide" as used herein includes, in a broad sense, substituted polyamides obtained by addition-modifying polyamides with not only ethylene oxide but also other alkylene oxides.

The N-substitution ratio in these modified polyamides having N-substituted amide bonds is about 5 to 100%, preferably about 10 to 50%, of the number of hydrogen atoms in the amide group.

Furthermore, the modified polyamide having an N-substituted amide bond can be further treated with an epoxy compound having a photoreactive double bond to introduce a photoreactive double bond into a portion of the substituted hydroxyl group, for example, to make the modified polyamide more clearly defined. It is possible to obtain a photosensitive polyamide resin composition that provides a relief image with excellent quality. The epoxy compound having a photopolymerizable double bond used here is mainly a compound having the following general formula.

Here, R is hydrogen, alkyl, halogen, haloalkyl, and A is ester, amide, ether,
These are alkylene and urethane bonds, and n is an integer of 0 to 3. Specific examples of these include glycidyl (meth)acrylate, glycidyl (meth)α
-chloroacrylate, N-glycidyl acrylamide, etc., but are not limited to these. Also usable are compounds obtained by reacting a portion of the epoxy groups of polyepoxide with carboxylic acids, amines, alcohols, etc. having double bonds.

The reaction between a modified polyamide having an N-substituted amide bond and an epoxy compound having a photopolymerizable double bond is carried out in a solution or in a molten system, but it is particularly difficult to achieve its purpose in the step of preparing a photosensitive polyamide resin composition. can be achieved. Specifically, for example, the step of dissolving N-hydroxyethylated polyamide in a solvent such as alcohol or an alcohol/water mixture, and further adding a photopolymerizable monomer, a photopolymerization initiator, and a thermal polymerization inhibitor to the polyamide solution The reaction can proceed at the stage of dissolving, mixing and ripening conventional auxiliary additive components such as additives. The reaction temperature is 30 to 150°C, and the reaction time is 0.5 to 48 hours, preferably 60 to 90°C, and 1 to 24 hours. The reaction solvent is preferably a mixed solvent of alcohol/water.

The reaction between the modified polyamide and the epoxy compound is considered to be an addition reaction between the hydroxyl group of the polyamide and the epoxy group, and it proceeds simultaneously with the addition reaction to the hydroxyl contained in the solvent alcohol, water, and other photoreactive monomers. However, if the reaction conditions are constant, the amount added to the modified polyamide can be controlled by the amount of epoxy compound added. The amount added is usually 0.1 to 20 wt%, preferably 0.5 to 5 wt%, based on the polyamide.

The photopolymerizable monomer used in the present composition may be any photopolymerizable monomer having at least one double bond. For example, alkoxyalkyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, benzyl (meth)acrylate, hydrogen (meth)acryloyloxyethyl phthalate, β-
Hydroxyethyl-β' (meth)acryloyloxyethyl phthalate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, N,
N'-methylenebis(meth)acrylamide, N
- allyl (meth)acrylamide, ethylene glycol di(meth)acrylate, as well as acrylic acid or methacrylic acid adducts to alkylene or polyalkylene glycol diglycidyl ether, triacrylic formal, trimethylolpropane tri(meth)acrylate, Examples include, but are not limited to, addition reaction products of polyamines and epoxy compounds having double bonds.

These photopolymerizable monomers can be present in the composition in amounts ranging from 10 to 90
% by weight, preferably 20 to 60% by weight,
Depending on the required performance of the photosensitive resin plate, they can be used alone or in combination of two or more. In particular, in order to obtain a flexible plate, it is advantageous to use 10 to 40% by weight of a monomer having one double bond as the photoheavy monomer so that the resulting crosslinked structure is relatively loose.

Similarly, in the composition of the present invention, 2 to 40% by weight.
Compounds that do not take part in the chemical reaction during the curing reaction, such as plasticizers and extenders for polyamides, may be added. Furthermore, as a photopolymerization initiator for rapidly carrying out the photocuring reaction of the composition of the present invention, all conventionally known compounds can be used, such as benzoins, benzophenones, anthraquinones,
Examples include benzyls and diacetyls. The photopolymerization initiator is preferably used in an amount of 0.01 to 10% by weight based on the total amount of the composition.

Furthermore, in order to increase the storage stability of the composition of the present invention, conventionally known thermal polymerization inhibitors can be added, such as phenols, hydroquinones,
Examples include catechols, and they are preferably added in an amount of 0.01 to 10% by weight based on the total amount of the composition.

A typical method for producing the composition of the present invention includes, for example, heating and dissolving a modified polyamide in an alcoholic solvent, adding a photopolymerizable monomer, a photopolymerization initiator, a thermal polymerization inhibitor, etc., and stirring and mixing with heat. . When introducing a photoreactive double bond into polyamide, it is preferable to add an epoxy compound having a double bond after dissolving the polyamide.

In order to form a photosensitive layer from the above-mentioned mixed solution, for example, it is formed into a sheet by dry film formation and adhered onto a support. When forming a printing plate, a negative film having a transparent image area is closely adhered to the photosensitive layer prepared as described above, and the photosensitive composition is hardened by irradiating it with ultraviolet light of usually 300 to 400 μm.

Then, by dissolving and removing the portion corresponding to the non-image area, for example, with an alcohol/water mixture or water, a relief image corresponding to the image area is formed on the support.

The photosensitive polyamide resin composition of the present invention has good washability during development, and the relief images obtained from the product of the present invention are particularly free from incurs, are flexible, clear images, and have deep white areas. Furthermore, when a modified polyamide prepared by addition reaction with an epoxy compound having a photopolymerizable double bond is used, a relief image with even better image reproducibility can be obtained. Furthermore, by selecting the type of modified polyamide, it is possible to obtain a system with a high development speed and a system that can be washed out with water.

The flexible printing plate obtained from the composition of the present invention uses a flexible, low-stretch plastic film as a support and can be easily attached to a cylinder with a small diameter. It also has a moderate elasticity, so it has the characteristic of reducing the thickness of fine lines on printed matter, and is particularly suitable for business form printing. Next, the present invention will be explained in more detail with reference to Examples.

Note that parts used in the examples are based on parts by weight.

Example 1 BASF copolyamide “Ultramid 1C”
100 parts of potassium carbonate, 0.5 parts of potassium carbonate, and 400 parts of ethylene carbonate were mixed, and the mixture was heated and stirred at 180° C. for 6 hours in a nitrogen stream. After cooling the product, 100 parts of a mixture of etherate and water (80 parts/20 parts weight ratio) was added to dissolve the product, reprecipitated in acetone, extracted, washed, and then heated at 60°C for 6 hours.
A modified polyamide powder was obtained by drying with hot air. This modified polyamide was analyzed (the analysis method was based on the method described in J.Poly.Sci., VOL.XV, page 430, (1956)), and the N substitution rate was 33
%, and the average polyglycol chain length was 3.1.

After heating and dissolving 50 parts of this modified polyamide in 60 parts of an ethanol/water mixture (80/20 weight ratio) at 80°C, glycidyl methacrylate (abbreviated as GMA) was prepared.
2 parts were added and the mixture was heated and stirred at 75°C for 0.5 hour. To this, 10 parts of diepoxy ester (abbreviated as Pr) obtained by the reaction of 1 mole of propylene glycol diglycidyl ether and 2 moles of acrylic acid, and a reaction product of 1 mole of metaxylylene diamine and 4 moles of glycidyl methacrylate (abbreviated as GX). ) 5 parts, β-hydroxyethyl-β'-acryloyloxyethyl phthalate (abbreviated as HOA) 20 parts, benzenesulfonbutyramide 10 parts, diethylene glycol 5
1 part and 1 part of benzyl dimethyl ketal, and heated to 75°C.
The mixture was heated and stirred for 4 hours.

The mixed solution thus obtained was cast onto a polyester film coated with a polyurethane adhesive and dried at 60°C for 6 hours to give a photosensitive layer thickness of 0.7.
A laminated sheet of mm was produced. The surface of the sheet was coated with an ethanol/water mixture (80/20 weight ratio), a 100 μm thick polyester film was adhered to the sheet, and the sheet was left in a dark place for 5 hours.

Peel off the cover film and apply a grayscale negative (Stouffer 21Step) to the surface of the photosensitive layer for sensitivity measurement.
Sensitivity Guide) and image reproducibility evaluation 133
Line negative (dot area with dot density of 3, 5, 10%, diameter
Independent points of 200μ and 300μ, thin line parts of width 70μ and 100μ,
(including white areas of 100μ, 200μ, 300μ),
The image was exposed using a 3KW mercury lamp exposure device until the gray scale sensitivity (GS sensitivity) reached 17.5.

After exposure, wash with ethanol/water (80/
A relief image was obtained by dissolving and removing the unexposed areas using a mixed solvent (20% by weight) at 30°C for 1 minute. The image area obtained completely reproduced all the negative images, and was particularly good with deep white areas. The hardness of the exposed photosensitive layer was Shore D35, and incurring was unlikely to occur.

Further, when business forms were printed using oil-based ink using a printing plate obtained from this photosensitive composition, good printed matter was obtained.

When sheeting this photosensitive composition stock solution,
I carried out a felt sieve, but the felt was not clogged. In addition, after storing the photosensitive plate at 50℃ for 60 days,
Plate making and evaluation were carried out in the same manner, but the various properties remained almost unchanged.

Example 2 100 parts of CM4000 nylon (ternary copolymerized nylon manufactured by Toray Industries, Inc.) and 400 parts of ethylene oxide were placed in an autoclave, and after stirring under pressure and heating at 70°C for 16 hours, unreacted ethylene oxide was released and removed. The resin part was washed with water, extracted, and dried under reduced pressure at 60°C to obtain a copolymerized modified polyamide with an N substitution rate of 35% and an average polyglycol chain length of 2.8.

50 parts of this copolymerized modified polyamide was mixed with ethanol/
After heating and dissolving at 80°C in 60 parts of a water mixture (80/20 weight ratio), 36 parts of 2-hydroxy-3-phenoxypropyl acrylate (abbreviated as HPPA), Pr-10
1 part of GX, and 1 part of benzyl dimethyl ketal were added and mixed at 75°C for 3 hours.

The thus obtained mixed solution was evaluated for sheeting and plate making in the same manner as in Example 1. A relief image with shore D hardness of 33 and almost good reproducibility was obtained.

Examples 3 to 4 In Example 1, CM4000 nylon (ternary copolymer nylon manufactured by Toray Industries, Inc.) and CM8000 nylon (quaternary copolymerized nylon manufactured by Toray Industries, Inc.) were used instead of “Ultramid 1C”. Modified polyamides with N substitution rates of 30% and 33% and average polyglycol chain lengths of 2.5 and 3.1, respectively, were obtained by the same modification method as in Example 1.

Using these polyamides, they were pretreated with GMA in the same manner as in Example 1, and then made into sheets and evaluated for plate making in the same manner as in Example 1.
28 and 30 clear relief images were obtained.

Example 5 By changing the polyamide modification conditions in Example 2, the N substitution rate was 40%, and the average polyglycol chain length was 4.1.
A copolymerized modified polyamide was obtained. Using this modified polyamide, sheet-forming plate-making evaluation was performed in the same manner as in Example 2. Shore D hardness was 28, and a relief image with almost good reproducibility was obtained.

Example 6 By changing the polyamide modification conditions in Example 1, the N substitution rate was 56%, and the average polyglycol chain length was 5.6.
A modified polyamide was obtained. Using this polyamide, a photosensitive sheet was prepared using the same composition and method as in Example 1, and the same exposure was performed. After exposure, the unexposed areas were dissolved and removed using 25°C water using a brush washer to obtain a relief image. The image area obtained almost completely reproduced the negative image and was clear. The hardness of the exposed photosensitive layer was Shore D28.

Example 7 BASF copolyamide “Ultramid 1C”
After powdering and suspending in 800 parts of tetrahydronaphthalene, 6 parts of boron trifluoride etherate were added. The mixture was heated to 150° C. with stirring, 50 parts of epichlorohydrin was added dropwise, and the mixture was stirred and heated at the same temperature for about 2 hours, then cooled, filtered, and dried to obtain a hydroxychloropropylated polyamide.

Using this polyamide, sheet formation and plate making evaluation were carried out in the same manner as in Example 1, and a sharp relief image with a shore D hardness of 38 and less incurl was obtained.

Claims (1)

[Scope of Claims] 1. A photosensitive polyamide resin composition comprising a polyamide having a bond represented by the following general formula as a resin component and a photopolymerizable monomer and a photopolymerization initiator. (n is 0 or an integer from 1 to 10; R is H, alkyl, haloalkyl, or aryl)