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JP-7855423-B2 - Disposal method for aqueous developer waste liquid

JP7855423B2JP 7855423 B2JP7855423 B2JP 7855423B2JP-7855423-B2

Inventors

  • 中村 晃直
  • 長谷川 亮介

Assignees

  • 旭化成株式会社

Dates

Publication Date
20260508
Application Date
20220622

Claims (8)

  1. A method for treating aqueous developing waste liquid generated by developing flexographic printing plates using an aqueous developing solution, A step of recovering a recovered solution containing the developing accelerator and water from an aqueous developing waste liquid containing developing residue, a developing accelerator and water , by distillation carried out at 100 hPa or less , The process involves mixing the recovered liquid with an aqueous developer to reuse it for developing flexographic printing plates, Includes, The aforementioned developing accelerator is given by the following formula (A1): Formula (A1): R 1 O(A 1 O) n R 2 (In the formula, R1 and R2 are each independently an alkyl group having 2 to 6 carbon atoms or an alkenyl group having 2 to 6 carbon atoms. A1 is an alkylene group having 2 to 4 carbon atoms. n is an integer between 1 and 5. It contains a compound represented by, The amount of the compound represented by formula (A1) contained in the recovered liquid is 25% by mass or more and 61% by mass or less, based on the amount of the compound represented by formula (A1) contained in the aqueous developing waste liquid. Method for disposing of aqueous developer waste liquid.
  2. The aforementioned recovery reduces the volume of the aqueous developing waste liquid to a range of 1/7 to 1/2 of the volume of the aqueous developing waste liquid before recovery. The processing method according to claim 1 .
  3. The aforementioned aqueous developing waste liquid further contains a surfactant, The aforementioned surfactant is defined by the following formula (B1): Formula (B1): RO(AO) p H (In the formula, R is an alkyl group or aryl group having 10 to 20 carbon atoms. A is an alkylene group having 2 to 4 carbon atoms. p is an integer between 1 and 50. A compound represented by The processing method according to claim 1 or 2 .
  4. In the above formula (B1), R is an alkyl group or aryl group having 10 to 18 carbon atoms. A is an alkylene group having 2 to 4 carbon atoms. p is an integer between 6 and 10. The processing method according to claim 3 .
  5. The aforementioned aqueous developing waste liquid further contains an antifoaming agent, The recovered liquid further comprises the defoaming agent. The processing method according to claim 1 or 2 .
  6. The aforementioned defoaming agent contains a silicone compound, The processing method according to claim 5 .
  7. The amount of the recovered solution is adjusted so that the concentration of the compound represented by formula (A1) in the mixture of the recovered solution and the aqueous developer is within the range of 0.15 to 0.30% by mass. The processing method according to claim 1 or 2 .
  8. The process further includes reusing the recovered liquid to rinse the developed flexographic printing plate. The processing method according to claim 1 or 2 .

Description

This invention relates to a method for treating aqueous developing waste liquid. Printing plates containing photosensitive resin can be manufactured using computer-aided printing (CTP) technology, which involves directly drawing information processed on a computer onto the printing plate to create a relief. Among these technologies, flexographic printing, a type of letterpress printing, has the advantage of being applicable to various substrates because it uses soft materials such as rubber or synthetic resin for the printing plate. Printing plates (especially flexographic printing plates) produced using CTP technology are obtained by following a procedure that involves laser drawing on an infrared absorption layer on a photosensitive resin, exposing and curing the photosensitive resin layer, developing the uncured areas, drying the resulting plate, and then post-exposing it. Flexographic printing plates can be obtained by solvent development (dissolving and developing the uncured areas with a solvent developer), aqueous development (exfoliating and developing the uncured areas with an aqueous developer containing a surfactant), or thermal development (heating the printing plate and wiping the uncured areas with a non-woven fabric). However, solvent development and aqueous development both generate waste solutions. In solvent-based development, the developed solution is recovered and reused by distillation. Similarly, in aqueous development, a method for reusing water recovered by vacuum distillation has been disclosed (see, for example, Patent Document 1). International Publication No. 2003/005129 Brochure Figure 1 shows a schematic diagram of one embodiment of an apparatus for carrying out the method of the present invention.Figure 2 shows the relationship (overlapping) between the number of flexographic printing plates developed and the DBDG concentration of the aqueous developer in the developer tank. The following describes specific embodiments of the present invention, but the present invention is not limited to these embodiments, and various modifications are possible without departing from its essence. <Disposal method for aqueous developer waste liquid> One embodiment of the present invention is a method for treating aqueous developing waste liquid generated by developing a flexographic printing plate using an aqueous developing solution, comprising a step of recovering a recovery solution containing a developing accelerator and water from the aqueous developing waste liquid containing developing residue, a developing accelerator and water (hereinafter referred to as the "recovery step"), wherein the developing accelerator is of the following formula (A1): Formula (A1): R 1 O(A 1 O) n R 2 (In the formula, R1 and R2 are each independently an alkyl group having 2 to 6 carbon atoms or an alkenyl group having 2 to 6 carbon atoms. A1 is an alkylene group having 2 to 4 carbon atoms. n is an integer between 1 and 5. The present invention relates to a method for treating aqueous developing wastewater containing a compound represented by [the formula shown]. In the method according to this embodiment, the development accelerator, which decreases with repeated development, is recovered from the aqueous development waste solution. For example, by using a recovery solution containing the development accelerator instead of water as the solvent for the aqueous developer added to maintain the development accelerator concentration, the amount of aqueous developer added can be reduced while maintaining the concentration of the development accelerator in the aqueous developer. The method according to this embodiment will be explained using an example of an apparatus for carrying out the method. Figure 1 shows a developing system 1. The developing system 1 is, A developing device 2 for developing the flexographic printing plate 4; A developing solution tank 21 for storing aqueous developing solution is located inside the developing device 2; A brush 5 is placed inside the developing device 2 to rub the surface of the flexographic printing plate 4; A vacuum distillation apparatus 3 for distilling aqueous developing waste liquid; A concentration vessel 31 for storing and concentrating aqueous developing waste liquid is located inside the vacuum distillation apparatus 3; A developing solution supply pipe 61 that supplies the developing solution to the developing solution tank 21; A water supply pipe 62 that supplies water to the developing solution tank 21; A developer circulation pipe 63 supplies the aqueous developer stored in the developer tank 21 to the flexographic printing plate 4; A waste liquid discharge pipe 64 that sends the aqueous developer stored in the developer tank 21 to the concentration kettle 31; A recovery liquid return pipe 65 returns the recovery liquid, which has been recovered from the aqueous developing waste liquid accumulated in the concentration kettle 31, to the developing liquid tank 21; A