KR910004717B1 - Negative photosensitive-composition - Google Patents

Abstract

a negative photosesitive resin compsn. is composed of 10-30 wt.% sulfonic acid salt diazo cpd. of formula (I) as a jphotosensitive [X is (a); R1 and R2 are each H or C1-4 alkyl; R3 is H or C1-2 alkyl; Y and Z are each H or amino , 40-70 wt.% adhesive resin, 2-10 wt.% stabilizer, dyestuff and solvent. The adhesive resin comprises 30-60 wt.% hydroxymethacrylate, 20-50 wt.% methylmethacrylate, 20-50 wt.% alpha-cyanoacrylate and 5-10 wt.% acrylic acid, and the stabilizer comprises 5- sulfosalicylic acid and citric acid. The compsn. has a good weather- resistance.

Description

Negative photosensitive resin composition

The present invention relates to a negative photosensitive resin composition which can be applied to a negative type presensitized plate and form an image among negative type offset printing plates.

The offset printing plate that can print color color prints has fine irregularities on the surface, but it is called a flat plate because the irregularities cannot be detected by hands or eyes. The printing principle is that the flat plate has a hydrophilic part and a lipophilic part, and the ink is buried in the lipophilic part. The lipophilic portion becomes the causal portion and the hydrophilic portion becomes the non-caustic portion.

In the case of color printing, four printings of four primary colors are printed on four printing plates of blue, yellow, red and black. Therefore, the dots are one color and do not overlap. In addition, the offset printing plate has a negative type using negative film and a positive type using forge film as a master film.

In general, the photosensitive resin composition is composed of a sensitizer and an adhesive resin having a photosensitivity, a dye that makes the distinction between the exposed portion and the non-exposed portion, and a solvent that sufficiently dissolves the sensitizer and the adhesive resin. In the negative photosensitive resin composition, the diazo compound is widely used as a sensitizer. Diazo compounds are known to cause photocrosslinking reactions by photoreaction with polymer compounds. The following mechanism applies to this;

In the exposed portion, the photocrosslinked portion becomes lipophilic, so that the ink is well stained, and the non-exposed portion is washed out with the alkaline developer.

In general, diazo resins of photosensitive resin compositions used in negative PS plates are used as polycondensates of para-diazo diphenylamine and formaldehyde as follows:

(U.S.P 2,992,715, U.S.P 2,946,683)

(Synthesis method of diazo compound)

The presence of a methyl group at the end of the stomach has important significance in the photocrosslinking reaction. In other words, diazo compounds having no methyl group have relatively poor adhesion and sensitivity. When the diazo compound is photocrosslinked, the lipophilic becomes lipophilic and the ink is buried. The non-exposed part is hydrophilic by exposing the aluminum surface by alkali development.

The aluminum surface is filled with water instead of ink, thereby enabling flat printing (off-set printing). However, in the case of the diazo resin, solubility, photosensitivity, stability, and the like vary depending on the corresponding ion. Since hydrochloride is very poor in stability and easy to decompose, it is used as a double salt or sulfate of zinc chloride. However, in case of zinc chloride double salt, diazo resin can be decomposed if it is affected by moisture in the case of sulfate.

On the other hand, the role of the adhesive resin in the negative photosensitive resin composition is important. In particular, compatibility is critically important and if the compatibility is poor, since the coated surface after coating is uneven, it is not possible to expect good printing characteristics due to staining or spots after development. The properties of the adhesive resin required in the offset printing plate should be compatible with other additives, control of wear resistance, adhesion, hydrophilicity and lipophilicity in the developed image part, and also developability.

In addition, the diazo resin should be optically transparent in the UV region where it is absorbed and exposed. In other words, diazo resin should be free from UV interaction or molecular excitation in the region of 350-450nm.

It should also be completely free of diazoresin when stored. Although various resins are used as the adhesive resin, phenolic resins are not suitable. This is because the diazo group of the non-exposed part which has not been irradiated with light undergoes a pecoupling reaction with an alkaline developer, resulting in poor solubility.

Accordingly, an object of the present invention is to solve the above problems when using inorganic salts or sulfates as a conventional photosensitizer and at the same time can be used in the organic solvent and mixed with a water-insoluble polymer, and also the stability is higher than that of inorganic salts. It is to provide a negative photosensitive resin composition containing a photosensitizer using a superior organic salt.

It is also an object of the present invention to provide a negative photosensitive resin composition using a new adhesive resin in order to solve the problems occurring when using the conventional adhesive resin.

The object of the present invention is to use a sulfonate salt as a photosensitizer, and a copolymer of hydroxyethyl methacrylate, methyl methacrylate, α-cyanoacrylate and acrylic acid (weight average molecular weight 20,000-10) By using only).

The negative photosensitive resin composition according to the present invention may be coated on a base plate, particularly a metal plate such as aluminum, to exhibit photosensitivity and exhibit a negative image. Such a composition of the present invention comprises 10-30 parts by weight of a sulfonic acid organic salt diazo compound, which is a photosensitive agent represented by the following general formula; 40-70 parts by weight of a copolymer of hydroxyethyl methacrylate, methyl methacrylate, α-cyanoacrylate and acrylic acid; And dyes, stabilizers and solvents.

Wherein R₁ and R2 represent a hydrogen atom or an unsubstituted alkyl group having 1 to 4 carbon atoms: R3 represents a hydrogen atom or an alkyl group having 1 to 2 carbon atoms; Y and Z each represent a hydrogen atom or an amino group.

Similar to most diazo compounds, the diazo resins have an absorption maximum at 350-400 nm and maximum photosensitivity is also observed in this region.

In the case of the negative photosensitive resin composition, the photosensitive resin emulsion is coated on an aluminum metal plate having a thickness of 0.15 mm, the surface of which is anodized, and has its own roughness, and the coated metal plate is stored in a dark room. .

The physical properties required for the adhesive resin should be suitable for conditions such as clear images, increased lipophilicity by photocrosslinking, and distinction between lipophilic and hydrophilicity.

The adhesive resin in the present invention satisfied the above characteristics by using a copolymer resin of various monomers. That is, the adhesive resin is 30-60 parts by weight of hydroxyethyl methacrylate, 20-50 parts by weight of methyl methacrylate, 20-50 parts by weight of α-cyanoacrylate, and 5-10 parts by weight of acrylic acid. Resin, which is a copolymer of monomers composed of weight ratio, was used.

The mixing ratio between the adhesive resin and diazo resin also has a great influence on the phenomenon, exposure and resolution. In other words, when the relative ratio of diazo resin increases, photosensitivity increases, but developability worsens. When the relative ratio of diazo resin decreases, developability improves, but sensitivity and resolution decrease relatively.

Since the adhesive resin has a very high adhesiveness with a basic matrix minority, that is, anodized aluminum plate, a part of it remains even when the non-wire line develops when stored for a long time, resulting in spots or spots when printing. In order to compensate for this disadvantage, in the present invention, 5-sulfosalicylic acid and citric acid were added by 1-5% by weight, respectively.

Tables 1 and 2 below show the concentrations of the minimum point Dmin and the maximum point when 5-sulfosalicylic acid and citric acid were added in 1 parts by weight and 2 parts by weight, respectively, at 50 ° C. and 75% humidity. It is a comparison result of Dmax, and the weather resistance test shows the excellent storage of this diazo resin:

TABLE 1

Minimum and maximum concentrations of 5-sulfosalicylic acid and citric acid, respectively, when 1 part by weight is added.

TABLE 2

The minimum and maximum concentrations when 5 parts by weight of 5-sulfosalicylic acid and citric acid were added.

After the photosensitive resin was coated on the Aι plate, dyes were added in an amount of 1-5 parts by weight in order to sharpen the image formed when the exposure was performed. The dyes used may be Eisen spiron Blue GNH, Oil Orange, Oil Black 2HB, Oil Blue G Exyra, Oil Orange SS, Oil Red, Oil Red AS, Oil Violet, Oil Yellow OB, etc. (USP 4,275,138) In the present invention, OB 603 (maximum absorption at 603 nm, manufactured by Orient Kagaku Togyo Co., Ltd.), which can achieve diazo resin and color balance properly, was used.

The present invention is specifically illustrated by the following examples.

Example 1

Prepare the coating solution as follows. That is, 6.5 g of a copolymer in which benzoyl peroxide is used as a reaction initiator and methylmethacrylate, α-cyanoacrylate, and acrylic acid are added dropwise to react with dioxane, P-diazodiphenylamine-sulfonic acid, paraformaldehyde and toluidine. The coating solution was coated with 2.5 g of diazo resin, 60 g of ethyl cellosolve, 40 g of ethyl cellosolve acetate, 60 g of dichloroethane, 0.5 g of OB-603, 0.2 g of 5-sulfosalicylic acid, and 0.2 g of citric acid. It is then coated on a treated aluminum sheet with a thickness of 0.15 ml. The aluminum plate is a plate degreaseed with sodium phosphate, electropolished and anodized.

PS plate coated with the coating solution is dried for 3 minutes at 95 ℃ to completely remove the solvent. Ultraviolet light in the wavelength range of 330-480nm was exposed using a metal halide lamp. The exposure time of the metal halide emitting ultraviolet light was 180 seconds and the development was performed until the step guide 5-6 was developed.

In Table 3), a coating solution was prepared using a copolymer, a diazo resin, and an additive, and then coated on an aluminum plate to form a PS plate, and the optical density was measured by using a densitometer using a gray scale.

TABLE 3

Where A: 5-sulfosalicylic acid

B: citric acid

C: ethyl cellosolve

D: ethyl cellosolve acetate

E: Ethanol

F: dichloroethane

Weather resistance test: 50 ℃, humidity 75% 120 hours test

◎: Excellent

○: Normal

△: decrease

Comparative Example 1

It is the same as Example 1 except adding 0.6 g of OB-603 compared with Example 1.

Comparative Example 2

It is the same as Example 1 except adding 0.3 g of OB-603 compared with Example 1.

Example 2

Compared with Example 1, except that 0.1 g of 5-sulfosalicylic acid and 0.1 g of citric acid were added thereto.

Comparative Example 3

Compared with Example 2, the same as in Example 1 except that 0.3g of 5-sulfosalicylic acid and 0.3g of citric acid were added.

[Comparative Example 4]

Compared with Example 2, the same procedure as in Example 2 except that 0.3 g of 5-sulphosalicylic acid and 0.1 g of citric acid were added thereto.

Example 3

Compared with Example 1, the same as in Example 3 except that 60g of ethyl solosolve 40g of ethanol and 60g of dichloroethane were added.

[Comparative Example 5]

It is the same as Example 3 except adding 70g of ethyl solosolve, 50g of ethanol, and 60g of dichloroethanes compared with Example 3.

Comparative Example 6

Compared with Example 3, the same as in Example 3 except that 80 g of ethyl solosolve, 60 g of ethanol, and 60 g of dichloroethane were added.

Claims (5)

A negative photosensitive resin composition comprising 10-30 parts by weight of a photosensitive agent, 40-70 parts by weight of an adhesive resin, 2-10 parts by weight of a stabilizer, and the remainder of a dye and a solvent. The negative photosensitive resin composition according to claim 1, wherein the photosensitive agent is a sulfonate diazo compound represented by the following general formula;

In the above formula,

R 'and R2 are hydrogen atoms or unsubstituted alkyl groups having 1 to 4 carbon atoms; R 3 represents a hydrogen atom or represents an alkyl group having 1 to 2 carbon atoms; Y and Z represent atoms or amino groups. The method of claim 1, wherein the adhesive resin is composed of 30-60 parts by weight of hydroxymethacrylate, 20-50 parts by weight of methyl methacrylate, 20-50 parts by weight of alpha-cyanoacrylate, and 5-10 parts by weight of acrylic acid. The negative photosensitive resin composition which is 20,000-100,000. The negative photosensitive resin composition according to claim 1, wherein the stabilizer consists of 5-sulfosalicylic acid and citric acid, and the amount thereof is 1-5 weight ratio, respectively. The negative photosensitive resin composition of claim 1, wherein the solvent is selected from the group consisting of ethyl cellosolve, ethyl cellosolve acetate, ethanol, and dichloroethane.