JPS5916512B2 - Method for processing waste liquid from washing out photosensitive resin printing plates - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for treating waste liquid from washing out photosensitive resin printing plates.

Photosensitive resin printing plates have recently become rapidly popular because they are cheaper than conventional printing plates, are easier to handle during printing, and have excellent printing properties.

Creating a printing plate from a photosensitive resin printing original plate (making a plate)
For example, the procedure is as follows: That is, after a negative or positive film is closely attached to the photosensitive resin surface (hereinafter referred to as photosensitive layer) of a photosensitive resin printing plate, it is exposed to actinic rays, and then the unexposed areas are blown away using, for example, compressed air. A printing plate is made by a method such as spraying a solvent under a constant pressure or washing it out by brushing (scraping) with a brush with raised fibers. All of these operations are performed mechanically by a developing machine. Recently, photosensitive resin printing plates that can be made with water (tap water, etc.) especially during washing have become popular, touting their benefits in washing.

However, the washout liquid generated during plate making contains high concentrations of 0BOD (biochemical oxygen demand), SS (suspended solids), and oily substances, so if it is discharged directly into rivers, it will be subject to legal regulations. There is a big problem5 in discharging untreated wastewater as it is, as it has the potential to cause water pollution regardless of whether it is contaminated or not. In view of the current situation, the inventors of the present invention have conducted various studies on methods for treating waste liquid from washing photosensitive resin printing plates, and have arrived at the present invention as described below.

In other words, the present invention is directed to (2) soluble polyamides having an ether bond in the main chain (esters or amides containing one or more CH2=C-C0- groups (wherein R represents H or CH3) in the molecule; When treating the waste liquid washed out from a photosensitive resin printing plate made using a photosensitive resin composition containing as an essential ingredient and one or more sensitizers and/or thermal polymerization inhibitors, the waste liquid This is a method for treating waste liquid from washing out photosensitive resin printing plates, which is characterized by heat-treating at 30 to 80°C.

The washing waste liquid that is the target of the treatment method of the present invention is generated when an original film (negative or positive film) made of the photosensitive resin composition shown below is exposed to light, and the unexposed areas are washed away with water. do. Note that the water used as the washing liquid here is normally fresh water such as tap water, but water to which surfactants, etc. have been added for the purpose of improving workability, such as improving the dispersibility of the washed out resin, is used. The method of the present invention can also be applied when using. The photosensitive resin composition referred to here is a soluble polyamide (B) having an ether bond in its main chain.
It contains an ester or amide containing one or more groups (R represents HI or CH3) as an essential component, and in addition contains one or more sensitizers and/or thermal polymerization inhibitors.

(4) The town-soluble polyamide having an ether bond in the main chain of the component is a polyamide containing as a starting material any one of a dicarboxylic acid, a diamine, or a cyclic amide having one or more ether bonds in the molecule, and is preferably a normal polyamide. A copolyamide obtained by copolymerizing a polyamide with the above-mentioned monomers is used. Such polyamides are produced by conventional methods. dicarboxylic acid with an ether bond in the molecule,
A specific example of diamine or cyclic amide is HOOC
CH2OCH2COOH-HOOCCH2(0CH2C
H2] 10CH2C00H (l = 0 or an integer from 1 to 20) HOOCCH2CH2OCH2OCH2CH2CO
OH・HOOCCH2CH2(0CH2CH2)MOC
H2CH2COOH (m = 0 or an integer from 1 to 20) p
-HOOCCH2C6H4OCH2COOH-p-HO
OCCH2CH2-C6H4OCH2COOH・p-H
OOCCH2OC6H4OCH2COOH-p-HOO
Dicarboxylic acids such as CCH2OC6H4OC6H4OCH2COOH, NH2(CH2)XO(CH2)YO(
CH2) XNH2 (X, y = integer from 1 to 20) NH2C
H2CH2CH2-0-(CH2CH2O)ZCH2C
Examples include cyclic amides such as diamines of H2CH2NH2 (Z=0 or an integer from 1 to 20).

These dicarboxylic acids or diamines are usually used in the polymerization reaction by forming a salt with the corresponding diamine or dicarboxylic acid in advance. The dicarboxylic acid or diamine that forms such a salt may both have one or more ether bonds in the molecule, but it is sufficient that an ether bond exists in either one of the molecules. The salt thus formed can be made by homopolymerization or copolymerization with a salt of a cyclic amide, dicarboxylic acid, and diamine (which may or may not have an ether bond in the molecule). A soluble polyamide is produced. It goes without saying that the dicarboxylic acid mentioned above can be subjected to the polymerization reaction in the form of the corresponding acid chloride or anhydride.

The thus obtained polyamide having an ether bond in its main chain may be used alone, or two or more types of polyamide may be used as a mixture. Representative examples of esters or amides containing one or more CH2=C-CO groups in the molecule used as component (B) include alkyl (meth)acrylates, oxyalkyl (meth)acrylates. ,(
haloalkyl meth)acrylate, halooxyalkyl (meth)acrylate, glycidyl (meth)acrylate, (
Ring-opening polymer of glycidyl meth)acrylate, alkylene glycol di(meth)acrylate, polyalkylene glycol di(meth)acrylate, (meth)acrylamide, N-methylol(meth)acrylamide, N,N
'-Alkylene bis(meth)acrylamide, N,N'
-arylene bis(meth)acrylamide, etc.

The amount of ester or amide used is from 1 to 150 parts by weight, particularly preferably from 5 to 100 parts by weight, per 100 parts by weight of the polyamide having ether bonds in the main chain.

The sensitizer is a compound known as a sensitizer for photopolymerization of unsaturated compounds.

In some cases, two or more of these compounds are used in combination. Compounds that are effective as such sensitizers include anthraquinone or its derivatives, benzophenone or its derivatives, benzoin or its derivatives, aldehydes, ketones, sulfur compounds, halogen compounds, dyes such as methylene blue and riboflavin, and uranyl nitrate. The above ester or amide 100
0.01 to 50 parts by weight per part by weight is suitable. Also,
Thermal polymerization inhibitors include hydroquinone or its derivatives, phenol or its derivatives, nitro group-substituted benzene, benzoquinone or its derivatives, 1,4-naphthoquinone or its derivatives, 1,2-naphthoquinone or its derivatives, phenothiazine or its derivatives, etc. Yes, the amount used is 10% of the above ester or amide.
A suitable amount is 0.01 to 10 parts by weight per 0 parts by weight.

Furthermore, the above composition may contain 1 to 30% of the total amount of the composition.
Compounds that do not participate in chemical reactions in the curing reaction, such as plasticizers and extenders for polyamides in weight percent, may be added.

To form a photosensitive layer from a mixed solution of the above photosensitive resin composition, for example, after distilling off the solvent and drying, the granulated product is heated and pressed onto a support using a press or the like to form the photosensitive layer. A photosensitive layer is formed by forming or forming a sheet into a sheet by a dry film forming method and adhering it onto a support.

Alternatively, a photosensitive layer is formed on the support by a method such as dry film formation all at once on the support to obtain a printing original plate. Examples of the support for the photosensitive layer include iron, stainless steel,
A metal plate such as aluminum, a synthetic resin sheet such as polyethylene terephthalate, or a synthetic rubber sheet such as styrene-butadiene rubber is used, and the thickness of the photosensitive layer formed on the support is preferably 0.1 to 10 mm. Further, if necessary, the photosensitive layer can be adhered onto the support using an adhesive. An original film having a transparent image area is closely attached to the photosensitive layer of the photosensitive resin printing original plate prepared in this way, and exposed by irradiation with ultraviolet light of usually 300 to 400 mμ, and then the unexposed areas are covered with water. The printing plate is washed out, and waste liquid from washing is generated at that time.

There is a considerable amount of BOD in the washing waste liquid. SS or n
- Contains hexane extract, etc.

However, it can be processed by the following operation. That is, by setting the temperature of the washing waste liquid to 30 to 80°C, preferably 35 to 60°C, and stirring it gently, the resin components in the waste liquid coagulate and precipitate, and can be separated into resin and water. The preferred temperature for heating varies depending on the type of polyamide, the ratio of forming the photosensitive layer, etc., but considering workability during processing, etc., it is preferably 35 to 60°C. When the temperature is lower than the above range, it is difficult to coagulate and precipitate the resin component.

In addition, if it is too high, the resin may become sticky, which may impede workability. However, the purpose of the present invention can still be achieved. As described above, when the washing waste liquid is heated, the resin components contained in the waste liquid coagulate and precipitate.

The agglomerated resin component can be easily separated from the water by, for example, decantation or filtration. Furthermore, it is of course possible to use a flocculant together in the treatment of the present invention.

Examples of flocculants used in the present invention include ferric chloride,
Examples include polymer flocculants and aluminum sulfate. These are commercially available and can be appropriately selected and used. Furthermore, aluminum salts and iron salts lower the pH during the coagulation reaction by adding an appropriate amount of alkaline agent.
An alkaline agent such as sodium chloride is used to bring the temperature within a predetermined range. As described above, the treatment method of the present invention enables efficient treatment of washing waste liquid with simple operations.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 Equimolar salt of α,ω-diaminopolyoxyethylene and adipic acid obtained by adding acrylonitrile to both ends of polyethylene glycol having a number average molecular weight of 400 and reducing it with hydrogen: 50 parts by weight, ε 30 parts by weight of caprolactam and 20 parts by weight of an equimolar salt of hexamethylene diamine and adipic acid were melt-polymerized under normal conditions to obtain the relative viscosity (polymer 1f! was dissolved in 100 ml of chloral hydrate and measured at 25°C). , hereinafter the same): 2.28, and a polyamide with an ether bond concentration in the main chain of 0/N: 1.55 was obtained.

55 parts by weight of the polyamide obtained by the above method, 35 parts by weight of the reaction product of diglycidyl ether of ethylene glycol and methacrylic acid, 3 parts by weight of triethanolamine, 5 parts by weight of diethylene glycol, 1 part by weight of benzoin methyl ether, triphenylphosph. A methanol solution consisting of a composition of 1 part by weight of 1 part by weight of hydroquinone monomethyl ether and 0.3 parts by weight of hydroquinone monomethyl ether was applied to a thickness of 0.000 m2 to a thickness of 0.3 parts by weight.
After casting on a 2 mm polyester film, it was dried at 50° C. to obtain a transparent photosensitive original plate with a photosensitive layer thickness of 0.8 U.

A negative film consisting only of horizontal lines with an interval of 1/31n was adhered to this photosensitive original plate, and a 2kW ultra-high pressure mercury lamp was used to heat the film.
Exposure for 2 minutes from a distance of 5 CTIL, commercially available capacity 201
1. At 25°C in neutral water using a brush-type washing machine.
A washout process was performed for 5 minutes. When this operation was carried out on 10 A3 size plates, a cloudy washout waste liquid 202 having a concentration of about 5% was produced. An immersion type electric heater was put into this waste liquid, and the liquid was heated to 40°C while being gently stirred.
The liquid temperature was raised to . As the liquid temperature rose, the resin content coagulated and settled at the bottom of the container. The precipitated resin was filtered through a 50-mesh wire mesh. The degree of contamination of the washed waste liquid treated in this way is compared with that of the raw water before treatment, and is shown below.

Example 2 Washing waste liquid 201 with approximately 5% concentration of Example 1
into a container 202 with a bottom area of about 500 cT1i.
After standing for 4 hours, approximately 161 liters of supernatant water which became transparent was separated.

Approximately 1.9 liter of hot water was added to the remaining cloudy liquid 4e (liquid temperature 251C).
5e was added and the liquid temperature was raised to 40°C. As the liquid temperature rose, the resin sedimented and separated. This resin was filtered and separated in the same manner as in Example 1. The degree of contamination of the treated water in this case is as follows, and the waste liquid has been purified to a large extent. If the supernatant water is separated in advance in this way, the work will be easier than in the case of Example 1. Example 3 α, obtained by aminating both ends of polyethylene glycol with a number average molecular weight of 1,000 in the same manner as in Example 1.
Equimolar salt of ω-diaminopolyoxyethylene and adipic acid: 50 parts by weight, ε-caprolactam: 25 parts by weight,
Equimolar salt of hexamethylene diamine and adipic acid: 2
Relative viscosity: 2.3 by melt polymerizing 5 parts by weight under normal conditions
6. A polyamide with O/N: 2.05 was obtained.

55 parts by weight of the above polyamide, 15 parts by weight of the reaction product of m-xylylenediamine and glycidyl methacrylate, 20 parts by weight of 2-oxyethyl methacrylate, 3 parts by weight of triethanolamine, 5 parts by weight of diethylene glycol, 2 parts by weight of benzoin isopropyl ether. An ethanol/water (90/10 weight ratio) solution consisting of a composition of 0.2 parts by weight, 0.2 parts by weight of t-butylcatechol, and 0.05 parts by weight of ascorbic acid was cast onto a glass plate and peeled off after drying. A photosensitive resin sheet was obtained.

The thickness of this photosensitive resin sheet coated with adhesive is 0.2]
1! A photosensitive original plate was obtained by thermocompression bonding onto a polyester film (1). This photosensitive original plate was treated in the same manner as in Example 1, and
A cloudy washout waste liquid 20e with a concentration of about 3% (6 A3 size plates) was produced.

Claims (1)

[Claims] 1 (A) Soluble polyamide with an ether bond in the main chain (B) There are ▲ mathematical formulas, chemical formulas, tables, etc. in the molecule ▼ groups (
However, a photosensitive resin composition containing an ester or amide containing one or more of (R represents H or CH_3) as an essential component and one or more sensitizers and/or thermal polymerization inhibitors is used. When treating the waste liquid from washing out of photosensitive resin printing plates made by plate making, the waste liquid is
A method for treating waste liquid from washing out photosensitive resin printing plates, characterized by heat treatment at ℃.