Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Silver compound sensitizer containing
Reexamination Certificate
2001-02-23
2004-02-10
Baxter, Janet (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Silver compound sensitizer containing
C430S621000, C430S623000, C430S642000, C530S355000, C530S408000
Reexamination Certificate
active
06689556
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2000-048166, filed Feb. 24, 2000, the entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
The present invention relates to a method of producing water-soluble chain-extended gelatin and, more particularly, to gelatin of this type exhibiting improved filtering characteristics when redissolved. The present invention further relates to the use of gelatin thus produced as a photographic component.
Silver salt light-sensitive materials have advanced by using a silver halide and gelatin. In particular, gelatin has a wide variety of effects on photographs and participates in all steps from the beginning to the end of silver salt photography, e.g., preparation of silver halide grains, coating, drying, storage, photographing, processing, and image storage. As the recent silver salt light-sensitive material preparation technologies are becoming precise, requirements for photographic gelatin are also becoming extremely strict.
Efforts have been made to meet these requirements, and one method is to modify gelatin. Of various modifying methods, U.S. Pat. No. 5,187,259 or Jpn. Pat. Appln. KOKAI Publication No. 56-2324 has disclosed a method of extending the chain (increasing the molecular weight) of gelatin while the gelatin is kept water-soluble (so-called water-soluble chain-extended gelatin). This water-soluble chain-extended gelatin is useful, on a support layer in the production of photographic elements, as a disperse dye carrier layer in the production of microfilm products or as a rapid film hardener carrier layer in color emulsion products. U.S. Pat. No. 5,187,259 and Jpn. Pat. Appln. KOKAI Publication No. 56-2324 describe that the viscosity of a solution using this gelatin is high, so a high coating rate can be used when the gelatin is applied to curtain coating. Additionally, the protective colloid properties of water-insoluble photographically useful substances, such as silver halide grains and disperse dyes, can be improved on the basis of the increased molecular weight.
Since the molecular weight is increased, however, the viscosity of the gelatin solution rises to increase the loads on individual operations. Also, even a low-concentration solution has a high gelation rate, so the solution is difficult to handle during the production. Furthermore, the effect on the yield is large, and this influences the producing cost.
When this gelatin is used, therefore, purification by an ion-exchange resin or ultrafiltration is impractical for the above reasons. Hence, it is necessary to perform drying and powdering by minimizing the number of producing steps. When this is the case, however, producing problems (coating suitability and coated surface condition failure) caused by the filtering characteristics arise if the gelatin is used as a photographic component. Any patents including the aforementioned disclosed patents do not describe improves of these problems after the reaction. So, it has been desired to improve the filtering characteristics of a solution when powder gelatin is redissolved.
BRIEF SUMMARY OF THE INVENTION
It is an object of the present invention to provide a water-soluble chain-extended gelatin producing method which improves the filtering characteristics of a solution prepared by redissolving a powder of gelatin, without applying any producing load.
The above object is achieved by the following means.
(1) A method of producing a water-soluble chain-extended gelatin, comprising the steps of:
subjecting unreacted gelatin (to be referred to as source gelatin hereinafter) a source gelatin having a first isoelectric point, in aqueous solution, to a partial crosslinking reaction to form a reaction mixture comprising a partially crosslinked gelatin having a second isoelectric point;
filtering the reaction mixture;
adjusting a pH value of the filtered reaction mixture to a value equivalent to the second isoelectric point ±1.5; and
concentrating, drying and pulverizing the pH-adjusted reaction mixture.
(2) The method described in (1), wherein the partial crosslinking reaction is performed by using a compound selected from the group consisting of a bis-(vinylsulfonyl) compound and a compound capable of activating a carboxyl group.
(3) The method described in (1), wherein the partial crosslinking reaction is performed by reacting the source gelatin with a compound selected from the group consisting of a bis-(vinilsulfonyl) compound and a compound capable of activating a carboxyl group in an amount of 0.25 to 10 mmol per 100 g of source gelatin, at a temperature of 40 to 65° C., and a pH of not less than a value equivalent to the first isoelectric point for 1 to 8 hours wherein the source gelatin is in a form of an aqueous solution with a gelatin concentration of 6 to 25% by mass.
(4) The method described in (2) or (3), wherein the bis-(vinylsulfonyl) compound is selected from compounds represented by formulas 1 and 2:
where each R
1
independently represents a hydrogen atom, an alkyl group, an aralkyl group or an aryl group, wherein these groups may be substituted, and n represents 0 or 1;
where Y represents a vinyl group, A represents a single bond or a divalent coupling group, and each R
2
independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.
(5) The method described in claim (2) or (3), wherein the compound capable of activating a carboxyl group is selected from compounds represented by formulas 3 and 4:
where each of R
3
and R
4
independently represents an alkyl group, an aralkyl group, or an aryl group, wherein R
3
and R
4
may be combined to form a heterocycle together with the nitrogen atom; R
5
represents an alkyl group, an alkoxy group, a dialkylamino group, or an N-alkylcarbamoyl group, and X
−
represents a monovalent anion, wherein if R
5
contains, as a substituent, a sulfo group, a sulfoxy group, or a sulfoamino group, the compound may form an intramolecular salt without X
−
;
where R
6
represents an alkyl group, a cycloalkyl group, an alkoxyalkyl group, or an aralkyl group, and R
7
represents the group defined by R
6
of a group represented by formula 5:
where R
8
represents an alkylene group, each of R
9
to R
11
independently represents an alkyl group, wherein one of R
9
to R
11
may be a hydrogen atom, and two of R
9
to R
11
may be combined to form a heterocycle together with the nitrogen atom.
(6) The method described in (3), wherein the source gelatin is selected from the group consisting of an acid-processed bone gelatin and a lime-processed bone gelatin.
(7) The Water-soluble chain-extended gelatin produced by the method described in any one of (1) to (6).
(8) A silver halide photographic light-sensitive material comprising the water-soluble chain-extended gelatin produced by the method described in any one of (1) to (6).
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.
DETAILED DESCRIPTION OF THE INVENTION
Concerning a partial crosslinking reaction in a method of producing water-soluble chain-extended gelatin of the present invention, U.S. Pat. No. 5,187,259 and Jpn. Pat. Appln. KOKAI Publication No. 56-2324 may be refered. In this partial crosslinking reaction, a bis-(vinylsulfonyl) compound or a compound capable of activating a carboxyl group is used.
First, a bis-(vinylsulfonyl) compound will be explained below.
This bis-(vinylsulfonyl) compound is preferably selected from compounds represented by formulas 1 and 2 below.
In formula 1, R
1
represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms (e.g., a methyl group, ethyl group, iso-propyl group, or n-butyl group), an ar
Kawamoto Hiroshi
Sasaki Hiroki
Uchida Minoru
Baxter Janet
Fuji Photo Film Co. , Ltd.
Sughrue & Mion, PLLC
Walke Amanda C.
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