JPH0645579B2 - Base precursor - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a base precursor, and more particularly to a base precursor that can be preferably used in a heat-developable recording material.

Background of the Invention A base is a very general-purpose reagent used in various reactions (eg, hydrolysis reaction, polymerization reaction, color reaction, redox reaction, neutralization reaction, etc.). For example, many recording materials such as silver salt photographs and diazo photographs require a base during image formation.

When a wet image forming process such as a developing process using a developing solution is performed in image forming (including character forming) of a recording material, a base is generally contained in this processing solution (developing solution). On the other hand, when performing a simple wet image forming process by heating or the like, it is generally necessary to incorporate a base in the recording material. However, if the base is incorporated in the recording material as it is, during the storage period of the recording material, the base may adversely affect other components, or the base itself may deteriorate.
There was a problem with stability over time.

As a means for solving the above-mentioned problem, a method of using a precursor (base precursor), which is neutral or weakly basic during storage and can generate a base during image formation, instead of the base is considered. In particular, various types of compounds have been researched and developed for the thermal decomposition type base precursor which can be preferably used for the thermal development type recording material. Examples of conventionally known base precursors include urea or an ammonium salt of urea and a weak acid (Japanese Patent Publication No. 40-1699).
No.), hexamethylenetetramine or semicarbazide (US Pat. No. 3,157,503), triazine compounds and carboxylic acids (US Pat. No. 3,493,374), dicyandiamide derivatives (US Pat. No. 3,271,155), N-
Sulfonylureas (US Pat. No. 3,420,665), amine imides (Research Disclosure, 15
776, 1977), thermally decomposable acids represented by trichloroacetic acid (British Patent No. 998949), and the like.

However, none of these base precursors has sufficiently fulfilled the two requirements of stability during storage and rapid decomposition (base generation) during image formation.

[Summary of the Invention] Among the above-mentioned base precursors, the present inventor has used one having a relatively rapid base generation during image formation (as described above, this is generally low in stability during storage). , Isolate it from other components in the recording material (eg, as a fine particle dispersion, store in microcapsules, etc.)
Therefore, we attempted to achieve both stability during storage and rapidity of base generation during image formation. However, it has been revealed that it is difficult to effectively separate the above-mentioned base precursors from other components in the recording material because the hydrophobicity is insufficient.

A general method for producing a recording material comprises the steps of dissolving, emulsifying or dispersing the constituents of the recording material in an aqueous solvent to prepare a coating solution, coating the coating solution on a support, and drying. is there. According to the study of the present inventor, even if isolation means such as microcapsules is applied, if the hydrophobicity of the base precursor is insufficient, the base precursor is dissolved in the coating solution, and as a result, part of the base precursor is dissolved. It has been found that the recording material introduced is produced in contact with the constituents.

It is an object of the present invention to provide a base precursor having improved hydrophobicity in addition to weakening the basicity of the original base which is the original purpose of the base precursor.

Further, an object of the present invention is to provide a base precursor which can rapidly generate a base by heating.

The present invention provides a base precursor comprising a compound represented by the following formula (I).

[In the above formula (I), R ¹ is one selected from the group consisting of a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group, an aralkyl group, an arylsulfonyl group, and a heterocyclic residue. A valent group (each group may have one or more substituents), X is an oxygen atom or a sulfur atom, and B is a primary amine, a secondary amine, an amidine derivative, and It is a monovalent group corresponding to an atomic group obtained by removing one hydrogen atom bonded to a nitrogen atom from an organic base selected from the group consisting of guanidine derivatives.] In addition, it is derived from B in the above formula (I). It is particularly preferable that the organic base is a strong base having a pKa value of 12 or more.

[Effects of the Invention] The base precursor of the present invention has its basicity weakened and its hydrophobicity increased by converting an organic base into a urea derivative or a thiourea derivative.

The base precursor of the present invention has improved hydrophobicity so that the base precursor may come into contact with the constituents of the recording material during the production of the recording material as described above because the base precursor is dissolved in the coating liquid. It can be effectively prevented. Therefore, the base precursor of the present invention, in addition to the effect of the usual base precursor of enhancing the storage stability of the recording material by weakening the basicity of the original base, due to the contact of the base precursor and other components This has the advantage that it is possible to avoid a decrease in storage stability of the recording material.

Further, the base precursor of the present invention releases the base easily and quickly by heating, so that it can be preferably used for a heat-developable recording material. In particular, an organic base derived from B in the above formula (I) (corresponding to a generated base)
However, in the case of a strong base having a pKa value of 12 or more, in addition to the advantage that a strong base can be produced, there is also an advantage that the release of the base by heating proceeds particularly rapidly.

The base precursor of the present invention requires a base because it can be applied as a precursor of various kinds of organic bases selected from the group consisting of primary amines, secondary amines, amidine derivatives, and guanidine derivatives. There is also an advantage that an organic base most suitable for the reaction system can be arbitrarily generated.

Detailed Description of the Invention The base precursor of the present invention comprises a compound represented by the following formula (I).

R ¹ in the above formula (I) is a hydrogen atom, an alkyl group (preferably having 1 to 18 carbon atoms), a cycloalkyl group (eg, cyclopentyl group, cyclohexyl group, adamantyl group), an alkenyl group (preferably having a carbon atom number). 2 to 18), alkynyl group (preferably having 2 to 18 carbon atoms), aryl group (eg, phenyl group, naphthyl group, anthracyl group), aralkyl group (eg, benzyl group, diphenylmethyl group, triphenylmethyl group, 9-fluorenyl group, phenethyl group), arylsulfonyl group (eg,
Benzenesulfonyl group, p-toluenesulfonyl group),
Arylsulfonyl group (eg, benzenesulfonyl group, p
-Toluenesulfonyl group), and a heterocyclic residue (eg, pyridyl group, piperidyl group, pyrrolyl group, pyrrolidyl group,
And a monovalent group selected from the group consisting of quinolyl group, acridyl group, indolyl group, benzothiophenyl group, and benzimidazolyl group.

Among the groups that can form R ¹ above, an alkyl group, a cycloalkyl group, an aryl group, and an aralkyl group are particularly preferable. The number of carbon atoms of R ¹ (including the number of carbon atoms of the substituent when it has a substituent) is 6
The above is preferable.

Each group that can form R ¹ may have one or more substituents. The substituent is not particularly limited, but it is preferably a hydrophobic group. An alkyl group,
Examples of the substituent capable of substituting the cycloalkyl group, the alkenyl group, and the alkynyl group include a halogen atom, an amino group, an alkylamino group, a hydroxyl group,
Acylamino group, alkoxy group, dialkylamino group,
Examples thereof include a nitro group, a cyano group, an acyloxy group, a dialkylcarbamoyl group, an alkoxycarbonyl group, a dialkylsulfamoyl group and an alkylcarbonyl group. Examples of the substituent capable of substituting the aryl group, the aralkyl group, and the heterocyclic residue include an alkyl group, a cycloalkyl group, an alkenyl group, and an alkynyl group in addition to the above-mentioned respective substituents. .

X in the above formula (I) is an oxygen atom or a sulfur atom. X is preferably an oxygen atom.

B in the above formula (I) is an atomic group obtained by removing one hydrogen atom bonded to a nitrogen atom from an organic base selected from the group consisting of primary amine, secondary amine, amidine derivative, and guanidine derivative. Is a monovalent group equivalent to.

When the organic base (corresponding to the generated base) is a primary amine or a secondary amine, B can be represented by the following formula (IV).

[In the following formula (IV), R ⁴¹ and R ⁴² are each a hydrogen atom (provided that R ⁴¹ and R ⁴² are
⁴² are not both hydrogen atoms), an alkyl group,
Is it a monovalent group selected from the group consisting of a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group, an aralkyl group, and a heterocyclic residue (each group may have one or more substituents) ) Or a heterocyclic residue together with a nitrogen atom in which R ⁴¹ and R ⁴² are adjacent (the heterocyclic residue may have one or more substituents)
Of the respective groups that can form R ⁴¹ and R ⁴² , an alkyl group, a cycloalkyl group, and an aralkyl group are particularly preferable.

The substituent is not particularly limited, but the carbon atom of R ⁴¹ or R ⁴² adjacent to the nitrogen atom of the above formula (IV) preferably has an imino group (in this case, the formula (IV II) will be described later).

As mentioned above, it is particularly preferable that the organic base is a strong base having a pKa value of 12 or more. From the above points, B in the formula (I) is preferably a monovalent group corresponding to an atomic group obtained by removing one hydrogen atom bonded to a nitrogen atom from an amidine derivative or a guanidine derivative. The above-mentioned amidine derivative or guanidine derivative is represented by the following formula (II).

[In the above formula (II), R ²¹ , R ²² , and R ²³ are each a hydrogen atom (provided that
At least one of R ²¹ , R ²² , and R ²³ is a hydrogen atom), an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group, an aralkyl group, and a heterocyclic residue. R ²⁴ is a hydrogen atom, an amino group, an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, or an aryl group, wherein each group may have one or more substituents. ,
Is a monovalent group selected from the group consisting of an aralkyl group and a heterocyclic residue (each group may have one or more substituents), or is R ²¹ and R ²² , R ²¹ and R ²³ , R ²² and R ²⁴ , or R ²³ and R ²⁴ are bonded to each other to form a heterocycle] Of the respective groups capable of forming R ²³ , an amino group (including a case having a substituent is included. ) Is particularly preferable. That is, R ²⁴ in the above formula (II) is more preferably a monovalent group represented by the following formula (III). When R ²⁴ in the formula (II) is a monovalent group represented by the following formula (III), it is possible to produce a guanidine derivative having extremely strong basicity as a base.

[In the above formula (III), R ³¹ and R ³² are each a monovalent group selected from the group consisting of a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group, an aralkyl group, and a heterocyclic residue. Or each group may have one or more substituents, or R ³¹ and R ³² together with the adjacent nitrogen atom may form a heterocyclic residue (wherein the heterocyclic residue is one or more It may have a substituent)
Of the respective groups capable of forming R ³¹ and R ³² , an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group, an aralkyl group, and a heterocyclic residue are preferable, and an alkyl group is preferable. Groups, cycloalkyl groups, and aralkyl groups are especially preferred.

The compound represented by the above-mentioned formula (I) which constitutes the base precursor of the present invention is a precursor which, as represented by the following formula (V), binds with each other to release 2 mol or more of a base per mol. You may form.

[In the above formula (V), X and B have the same definitions as X and B in the above formula (I), respectively, and R ⁵ may constitute R ¹ in the above formula (I). It is an n-valent group derived from each possible group, and n is an integer of 2 or more (preferably 2 to 6)] Further, B in the above formula (I) is represented by the formula (II). When it is a monovalent group derived from a compound and R ²⁴ in the formula (II) is a monovalent group represented by the formula (III) (when the generated base is a guanidine derivative), As shown in formula (VI), both of the two amino groups of the guanidine derivative (including those having a substituent) may be blocked according to the base precursor of the present invention.

[In the above formula (VI), R ⁶¹ and R ⁶² are the same as R ¹ and R ⁶² in the above formula (I).
X has the same definition as X in formula (I) described above, and R ⁶³ , R ^64, and R ⁶⁵ represent R ²¹ and R ²² in formula (II) described above. , And R ^23. ] As described above, the base released from the compound represented by the formula (I) (corresponding to HB) is a strong base having a pKa value of 12 or more. Is preferred. The above pKa value is 13
It is more preferable that the above is satisfied.

The melting point of the compound represented by formula (I) is 50 ° C to 15 ° C.
The temperature is preferably 0 ° C, more preferably 80 ° C to 120 ° C. The total number of carbon atoms of the compound represented by formula (I) is preferably 20 or more, more preferably 30 or more.

Hereinafter, typical specific examples of the compound represented by the formula (I) will be shown, but the present invention is not limited thereto.

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) (22) (23) (24) (25) (26) (27) (28) (29) (30) (31) (33) (34) (35) (36) (37) (38) (39) (40) (41) (42) (43) The compound represented by the formula (I) as described above is H-
The organic base corresponding to B is dissolved in any solvent (eg, methylene chloride, ethyl acetate, etc.), and the isocyanate or isothiocyanate corresponding to R ¹ -N = C = X is dissolved at a low temperature (preferably 10 ° C or lower). ) It can be easily produced by dropping and stirring under the conditions.

The synthesis examples of the base precursors (2), (17), and (19) are shown below. Other base precursors can be synthesized by the same method.

[Synthesis Example 1] Synthesis of Base Precursor (2) 86 g of 1,2,3-tricyclohexylguanidine was added to 3
This was dissolved in 00 ml of methylene chloride, and 35.3 g of cyclohexyl isocyanate was added at 10 ° C or lower. After stirring for 1 hour as it was, the solvent was distilled off to obtain crystals. When this was recrystallized using hexane, 50 g of white crystals of the base precursor (2) were obtained. Melting point is 8
It was 8 to 93 ° C.

Synthesis Example 2 Synthesis of Base Precursor (17) 80 g of 1,2,3-tricyclohexylguanidine
It was dissolved in 400 ml of methylene chloride purified by dry column chromatography of alumina, and 25 g of xylylene diisocyanate was added dropwise while keeping the internal temperature at 10 ° C. After stirring this at room temperature for 1 hour, the solvent was distilled off, hexane was added to the residue, and the insoluble matter was filtered off. The solvent was distilled off under reduced pressure to obtain 45 g of crystals of the base precursor (17). The melting point was 118 to 123 ° C.

[Synthesis Example 3] Synthesis of base precursor (19) 1,2,3-tricyclohexylguanidine 151.5
g was dissolved in 1000 ml of ethyl acetate, and Takenate D-1 was added.
182 g of 10N (manufactured by Takeda Pharmaceutical Co., Ltd.) was gradually added. After stirring this for 1 hour, the whole was reduced to 400
The solvent was distilled off until the volume became ml. When this was poured into 2 hexane, a viscous insoluble matter was precipitated. The supernatant was removed by decantation, 1 hexane was further added, and the mixture was vigorously stirred, whereby the base precursor (19) was crystallized as an insoluble component. The crystals obtained were filtered and air dried. Yield 221g, melting point 82-122 ° C (decomposition)
Met.

The base precursor of the present invention composed of the compound represented by the formula (I) easily releases an organic base corresponding to H-B by heating. Generally, the heating temperature is preferably 80 to 200 ° C. Further, when B in the formula (I) is a monovalent group derived from the compound represented by the formula (II) described above (when the released base is an amidine derivative or a guanidine derivative), The heating temperature is preferably 80 to 150 ° C.

Hereinafter, a specific method of using the base precursor of the present invention will be described.

The base precursor of the present invention, in addition to image formation using a recording material such as the silver salt photographic method and the diazo photographic method as described above, an anionically polymerizable adhesive, coating film formation of a coating, sealing / caulking agent, cleaning It can be effectively applied to various chemical reaction systems that require a basic component such as an agent.

In the silver salt photography, development, that is, redox reaction between a silver halide and a developing agent is carried out under alkaline conditions. By adding the base precursor of the present invention to the light-sensitive material for silver salt photography, it is possible to cause development by simply heating after exposure. In this case, it is desirable that the base precursor is isolated from other components in the light-sensitive material by emulsion dispersion, solid dispersion, microcapsules and the like. As the isolation means, a method of solid-dispersing in the form of fine particles is the easiest and preferable. As described above, the base precursor of the present invention has an advantage that it can be effectively separated from other components in the light-sensitive material.

In the diazo photographic method, as shown in the following formula, the residual diazonium salt in the unexposed portion and the coupler are subjected to a coupling reaction under alkaline conditions to form an azo dye.

When the present invention is applied to the diazo photographic method, for example, in a dry method, a diazonium salt is coated with a base precursor together with a diazonium salt in a state in which they are isolated from each other (solid dispersion of the base precursor, etc.), and after exposure, heat development is performed. An azo dye image can be obtained by. In the conventional heat development method diazo photography, a base precursor such as ammonium carbonate or hexamethylene tetramine was used, but the development time was long and the stability of the photosensitive paper was not good. On the other hand, the use of the base precursor of the present invention enables rapid image formation and also improves the stability of the photosensitive paper.

In addition, the base generated from the base precursor of the present invention,
It can be used as a basic catalyst for the polymerization reaction of an anionically polymerizable monomer. The anionic polymerization is not particularly limited and can be applied to various fields such as adhesives, coating agents, sealing / caulking agents and the like.

The present invention can also be applied to products that require a basic component such as detergents and fungicides. When the present invention is applied to the products as described above, the base can be generated by heating the product containing the base precursor during use. Therefore, by applying the present invention, these products can be made neutral, safe and stable.

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

[Example 1] 24.0 g of a base precursor (a) represented by the following formula
Was dispersed in 176.0 g of a 4% aqueous polyvinyl alcohol solution using Dynomill, and was applied onto a polyethylene terephthalate film using a # 40 wire bar and dried at 40 ° C. for 30 minutes. A coated sample of the base precursor (a) was prepared. This was heated to 125 on a hot plate, the sample was taken out after a fixed time, and the film surface pH was measured. The measurement results are shown in FIG. FIG. 1 is a diagram in which time is plotted on the horizontal axis and pH is plotted on the vertical axis with respect to the above measurement results.

(Base precursor a) [Example 2] The coated sample of the base precursor (a) prepared in Example 1 was placed in a metal box, sealed, and stored under a temperature condition of 50 ° C for 3 days. Similarly, changes in the pH of the membrane surface during heating were measured. The measurement results are shown in FIG. 1 as in Example 1.

[Comparative Example 1] Guanidine trichloroacetate (base precursor x) 2
After dissolving 4.0 g in 50% ethanol aqueous solution 176.0 g, 4% polyvinyl alcohol aqueous solution 17
6.0 g was added and precipitated, and dispersed using Dynomill. This was coated on a polyethylene terephthalate film in the same manner as in Example 1 and dried to prepare a coated sample of the base precursor (x).

The result of measuring the change in the pH of the film surface during heating in the same manner as in Example 1 is shown in FIG.

[Comparative Example 2] The coated sample of the base precursor (x) prepared in Comparative Example 1 was placed in a metal box, hermetically sealed, and stored under a temperature condition of 50 ° C for 3 days. Similarly, changes in the pH of the membrane surface during heating were measured. The measurement results are shown in FIG. 1 as in Example 1.

[Example 3] In place of 24.0 g of the base precursor (a) used in the preparation of the coated sample of the base precursor (a) of Example 1, the same amount of the base precursor (b) represented by the following formula was used. In the same manner as in Example 1, a coated sample of the base precursor (b) was prepared.

The result of measuring the change in the pH of the film surface during heating in the same manner as in Example 1 is shown in FIG.

(Base precursor b) [Example 4] The coated sample of the base precursor (a) prepared in Example 3 was placed in a metal box, sealed, and stored under a temperature condition of 50 ° C for 3 days. Similarly, changes in the pH of the membrane surface during heating were measured. The measurement results are shown in FIG. 1 as in Example 1.

As is clear from the above results shown in FIG. 1, it is understood that the base precursor of the present invention rapidly releases the base upon heating. It is also apparent that when stored at 50 ° C. for 3 days, the base precursor of Comparative Example releases the base during storage, whereas the base precursor of the present invention shows almost no deterioration due to storage. .

[Brief description of drawings]

FIG. 1 is a plot of the measurement results of changes in the pH of the membrane surface during heating in Examples 1 to 4 and Comparative Examples 1 and 2, in which time is plotted on the horizontal axis and pH is plotted on the vertical axis.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location C07D 239/06 239/10 295/20 G03C 1/498 502 8910-2H 1/61 501 8910-2H

Claims (9)

[Claims] 1. A base precursor comprising a compound represented by the following formula (I): [In the above formula (I), R ¹ is one selected from the group consisting of a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group, an aralkyl group, an arylsulfonyl group, and a heterocyclic residue. A valent group (each group may have one or more substituents), X is an oxygen atom or a sulfur atom, and B is a primary amine, a secondary amine, an amidine derivative, and It is a monovalent group corresponding to an atomic group obtained by removing one hydrogen atom bonded to a nitrogen atom from an organic base selected from the group consisting of guanidine derivatives]. 2. The number of carbon atoms of R ¹ in the above formula (I) (in the case of having a substituent, the number of carbon atoms of the substituent is included).
Is 6 or more, Claim 1
A base precursor according to the item. 3. The base precursor according to claim 1, wherein X in the above formula (I) is an oxygen atom. 4. The base precursor according to claim 1, wherein the organic base derived from B in the formula (I) has a pKa value of 12 or more. 5. The base precursor according to claim 1, wherein the organic base derived from B in the above formula (I) is a compound represented by the following formula (II): [In the above formula (II), R ²¹ , R ²² , and R ²³ are each a hydrogen atom (provided that
At least one of R ²¹ , R ²² , and R ²³ is a hydrogen atom), an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group, an aralkyl group, and a heterocyclic residue. R ²⁴ is a hydrogen atom, an amino group, an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, or an aryl group, wherein each group may have one or more substituents. ,
Is a monovalent group selected from the group consisting of an aralkyl group and a heterocyclic residue (each group may have one or more substituents), or is R ²¹ and R ²² , R ²¹ and R ²³ , R ²² and R ²⁴ , or R ²³ and R ²⁴ are bonded to each other to form a heterocycle]. 6. The base precursor according to claim 5, wherein R ²⁴ in the above formula (II) is a monovalent group represented by the following formula (III); [In the above formula (III), R ³¹ and R ³² are each a monovalent group selected from the group consisting of a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group, an aralkyl group, and a heterocyclic residue. Or each group may have one or more substituents, or R ³¹ and R ³² together with the adjacent nitrogen atom may form a heterocyclic residue (wherein the heterocyclic residue is one or more It may have a substituent)
Are formed]. 7. The base precursor according to claim 1, wherein the compound represented by the formula (I) has a melting point of 50 ° C. to 150 ° C. 8. The base precursor according to claim 1, wherein the compound represented by the formula (I) has a total number of carbon atoms of 20 or more. 9. The base precursor according to claim 1, which is used for a heat-developable recording material.