Bleach-Fixer Using a New Biodegradable Chelating Agent− Ultra-Rapid Processing Chemical ECOJET HQA-P-03 for Konica Color QA Paper −Okano, Satoshi ＊Ishida, Kenji ＊Kuse, Satoru ＊Employed, for a long time, as photographic bleach-fixing agents, have been ethylenediamine-N,N,N',N'tetraacetic acid iron(III) complex (EDTA-Fe) and the like. Ethylenediamine-N,N,N',N'-tetraacetic acid (EDTA)
has been employed in many industrial fields such as soap and detergent industry. However, a major problem
has been pointed out in that EDTA remains in the environment over an extended period of time due to its low
decomposition properties by microorganisms and results in adverse effects to the life in water-based environment. On the market, the German Photographic Chemistry Union (PIV : Photochemischen IndustrieEingetragener Verein) has initiated voluntary reduction of non-biodegradable chelating agents such as EDTAand the like. EU is now considering a similar regulation. Under such circumstances, Chemical Technology
Center*, in which products are developed from the important viewpoint of environmental protection, has studied replacement of biodegradable chelating agents. "Ultra-Rapid Processing Chemical ECOJET HQA-P-03 forKonica Color QA Paper" is characterized in that s,s-ethylenediamine-N,N’-disuccinic acid iron(III) complex(s,s-EDDS-Fe), which is a newly developed biodegradable chelating agent, has been placed into practice andexhibited excellent photographic bleaching capability even in rapid processing.

１Introduction

２ Development Target

On the market, PIV has initiated voluntary reduction

Even though the entire photographic industry is pay-of non-biodegradable chelating agents such as EDTA anding close attention to biodegradable bleaching agents, nothe like. EU is now considering a similar regulation.

commercially viable examples of biodegradable bleach-

Under such circumstances, Chemical Technology Cen-ing agents have been discovered in the field of rapid

ter, in which from the important viewpoint of environ-processing. The Chemical Technology Center is target-

ment protection, products are developed, has conducted

ing market introduction of a biodegradable bleaching

several technical developments earlier than competitors

agent which exhibits excellent bleaching capability evenand has succeeded in development of biodegradable

in ultra-rapid processing and is conducting studies ofbleaching agents １），２） . Currently, the Chemical Tech-market introduction of photographic chemical which isnology Center has studied commercial viability of s,s-environmentally excellent.

EDDS-Fe which is one of biodegradable bleaching agents
owned by said Chemical Technology Center and has
succeeded in the market introduction of ECOJET HQAP-03. Excellent photographic bleaching performance has
been realized even in ultra-rapid processing. Herein, thestudy results are reported.

３ Establishment of Biodegradable Bleaching Agent Technology: Establishment ofCore Technologies for an Environmental
Consciousness Chemical
It is known that chemicals, which have a structuresusceptible to enzyme reaction, are more readily biode-Table1 Development of Biodegradable Bleaching Agents by Photographic Industries＊Chemical Technology Center CI Manufacturing Division
Consumer Imaging Company

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gradable, since the biodegradation is a reaction in which

for photographic processing. Further, we have discov-chemicals are included in microorganisms in an activatedered that, of aminopolycarboxylic acid type chelating

sludge and undergo metabolic reaction through enzyme

agents, structures having Ⅰ)secondary amine, Ⅱ)reaction. Subsequently, we have discovered the relation-monoamine based, and Ⅲ) amide bond are specificallyship between biodegradability and molecular structureadvantageous for biodegradability. Table ２ shows the３），４）

presented

relationship between the biodegradability and the mo-in accordance with the Law Concerning the Examina-

lecular structure, while Fig. １ shows a list of chelatingtion and Regulation of Manufacture, etc. of Chemicalagents which have been surveyed, and Fig. ２ shows theSubstances. Subsequently, we have surveyed chelating

biodegradability test results, employing the MITI test

agents based on our discovery and succeeded in discov-

method, which has been accepted by OECD (the Organi-

ery of biodegradable chelating agents which are suitablezation for Economic Cooperation and Development) andwhile referring to data and references

Table2 Relationship between Molecuar Structure and Biodegradability

Fig.1 List of Chelation Agents

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also accepted by the Law Concerning the Examination
and Regulation of Manufacture, etc. of Chemical Substances. Subsequently, chelating agents, which exhibit at

４ Investigation for Commercial Applicationof s,s-EDDS-Fe

least 60 percent biodegradability, have tridentate or

Adaptability of s,s-EDDS-Fe for ultra-rapid processing

higher ligands, and form stable chelates with an Fe ion,

was evaluated. Fig. ３ shows the features of ECOJET

were evaluated for bleaching performance in photographic

HQA-P chemical.

processing. As a result, it was possible to discover a biodegradable bleaching agent, s,s-EDDS-Fe, which exhib-

４．１ Photographic Bleaching Performance during

ited excellent photographic bleaching performance. Fur-

Ultra-Rapid Processing (Silver Bleaching Capa-ther, as used herein, the term "s,s" is used to refer to anbility, Minimization of Leuco Dye Formation, andoptical isomer.

Storage Stability)
The bleaching agent, s,s-EDDS-Fe, exhibited silver
bleaching capability which was quite similar to adiethylenetriamine-N,N,N',N'',N'''-pentaacetic acid iron(III)complex (DTPA-Fe), while exhibiting minimized pH dependence, and was superior to EDTA-Fe. The minimization of leuco dye formation was slightly inferior to EDTAFe at a pH of less than 6.3, while the same was excellent
at a pH of more than or equal to 6.3. The storage stability was excellent, being the same as for DTPA-Fe.
Figs. ４ - １through ４- ３show the evaluation results,
and Table ３ shows the list of performance comparison
results.

Fig. 2 Biodegradability Test Results(MITI Test)

Fig.4-1 Silver Bleaching Capability

Fig.3 Features of ECOJET HQA-P Chemical

Fig.4-2 Minimization of Leuco Dye Formation

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Fig.4-3 Storage Stability

Table3 List of Performance Comparison Results

４．３

４．２ Commercial Application of a New
Biodegradable Bleaching AgentEdge Staining

It has been known that staining at the edge of paper

It was found that s,s-EDDS-Fe exhibited excellent pho-(edge staining) occurs due to bleaching agents. Effects oftographic bleaching performance even in ultra-rapid pro-practical use of s,s-EDDS-Fe for edge staining were in-cessing by adjusting the pH to at least 6.3. However, atvestigated, employing absorption spectra as well as prac-a pH of less than 6.3, the minimization of leuco dye for-tical processing. The results of the absorption spectra

mation was slightly insufficient. In order to realize more

showed that s,s-EDDS-Fe had properties similar to EDTA-

consistent processing performance, further investigation

Fe. Compared to DTPA-Fe, s,s-EDDS-Fe resulted in rela-

was performed. As a result, a technique was discovered

tively small absorbance in the visible region. Further, inin which s,s-EDDS-Fe was employed in combination withpractical processing, the combination of s,s-EDDS-Fe with

EDTA-Fe which resulted in excellent minimization ofEDTA-Fe resulted in less edge staining than DTPA-Fe.

leuco dye formation, whereby the commercial applica-DTPA-Fe, having a relatively large absorbance in thetion of the biodegradable chelating agent, s,s-EDDS-Fe,

visible region resulted in marked staining, even though

was achieved.

its residual amount was minimal in paper. By replacing
DTPA-Fe with s,s-EDDS-Fe, it was found that edge staining was minimized. Fig. ５ , ６ shows the results.

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Fig.5 Absorption Spectra

Fig.6 Edge Staining

Fig.7 New Granulation Technology

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５ket in a tablet form as the world's first product forTabletizing Technologies

minilabs.

In order to apply s,s-EDDS-Fe to ECOJET HQA Chemical, its tabletizing was investigated. In conventional tech-Konica intends to contribute to society while developing leading environmentally friendly technologies.

nology in which tablets are formed through granule formation, the bleaching portion is subjected to melt-granulation, and then blended with the fixing portion, water is

７ References

added as a binder so that physical properties of the re-１）Japanese Patent No. 3116194

sulting tablets are enhanced through the effects of melt-２）Japanese Patent No. 3208686

ing and the binder water. However, when s,s-EDDS-Fe３）"Kashinho no Kizon Kagaku Busshitsu Anzensei Tenken Data
Shu (Collection of Safety Inspection Data of Known Chemicalwas used, it was found that the conventional granulation

Substances in the Law Concerning the Examination and Regu-technology resulted in degradation of storage properties

lation of Manufacture etc. of Chemical Substances)", edited byof the resulting tablets. As a result, the investigation(Zai) Kagakuhin Kensa Kyokai４）Morio Yashiro and Shinsaku Shiraishi, Dai 42 Kai Saku To (Thewas conducted to overcome said problems.

42nd Complex, etc.) 1E02 (1992)

５．１ Investigations of Causes of the Degradation ofPhysical Properties and Establishment of a New
Granulation Technology
Differences in physical properties of bleaching agentswere compared, and degradation which causes duringstorage of tablets were investigated. As a result, s,s-EDDSFe was found to be markedly soluble in water. It wasalso found that during storage, s,s-EDDS-Fe was dissolvedin the binder water and the like, even though being in aminute amount, and reacted with reducing agents suchas fixing agents. Accordingly, a new granulation technology was investigated aiming at enhancement of the storage stability without resulting in degradation technology was investigated aiming at enhancement of the storage stability without resulting in degradation of physicalproperties, and without adding of water as a binder.
Fig. ７ shows granulation flow. In conventional granulation technology, only the bleaching agent was granulated. However, in the new granulation technology, thefixing agent was also granulated. As a result, a 2-part
granulation method was developed in which the bleaching agent as well as the fixing agent was coated withchemically inactive polyethylene glycol (PEG), so as toform a thin layer, whereby the enhancement of physicalproperties as well as the storage stability of tablets wereachieved.

６Summary

A commercially viable biodegradable bleaching agent
has been realized which exhibits excellent photographic
bleaching performance even in ultra-rapid processing.
Subsequently, an environmentally friendly chemical (ableach-fixing agent) has been introduced onto the mar-18

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