JP2000118147A - Heat coloring polymer, image recording medium using the same, and image recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image recording medium in which heat sensitivity is high and recording by a low output laser of a degree not causing ablation is enabled even in the case of utilizing a heat-mode image recording system using a laser and a different image-receiving is not necessitated and retention stability is excellent by using a novel polymer coloring (or decoloring) by only action of acid having catalytic amount or heat. SOLUTION: The image recording medium has a function generating acid by action of acid and furthermore propagating acid by action of acid generated by itself and/or has the function generating acid by heat. Further, the image recording medium contains a polymer incorporating at least one kind or more ethylenic unsaturated monomers which collectively have a function causing change in an absorption region of 360-900 nm within a molecule by action of acid, as a polymerization component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polymer (polymer) containing, as a polymerization component, a monomer containing a partial structure that generates an acid by heating or the action of an acid, and a partial structure that causes an absorption change upon contact with the acid. Further, the present invention relates to an image recording medium using the polymer having high sensitivity and good storability, and an image recording method using the same.

[0002]

2. Description of the Related Art A heat-sensitive recording material expresses an image area and a non-image area as a temperature difference distribution. Many schemes have been devised, such as changes in optical properties. This type of thermal recording medium is widely used as an output material for various printers, word processors, facsimile machines, etc. because of its advantages that a recorded image can be obtained by a dry and simple system and that it is maintenance-free. In recent years, with the progress of laser recording devices, applications to optical disks and plate making materials are being studied.

Conventionally, silver halide photographic materials requiring wet processing have been used as plate making materials. However, due to the demand for simplification of processing steps and the problem of environmental pollution caused by processing solutions, development of dry processing has been required. Desirably, several technical proposals have been made in recent years using the thermal recording method. From the viewpoint of resolution, image recording using a laser is preferable. For example, a method called dye ablation using a high-power laser has been developed.
164755, -149063, 7-1149
No. 065, etc., an image forming apparatus is disclosed in Japanese Patent Application Laid-Open No. 8-48053.
And No. 8-72400. In this system, a recording material having a dye composition composed of an image dye applied on a support, a substance having absorption in a laser wavelength range (infrared absorbing substance) and a binder is irradiated with laser from the dye layer side. Image recording is performed.
The energy provided by the laser causes a sharp local change in the imaging layer at the spot where the laser beam hits the material, thereby driving the material out of the layer.
According to the above patent publication, this is not a complete physical change (e.g., melting, evaporation or sublimation), but some kind of chemical change (e.g., bond breaking), rather than partial image dye removal. It is said to be complete elimination. In such a dye ablation method, a high-power laser is indispensable in order to increase the efficiency of removing the dye at the laser exposure site, and a dust collector is required to collect the removed dye. there were.

As a method that does not require a dust collector, a description of an ablation transfer type image recording method using a laser as a heat source is disclosed in US Pat. No. 5,171,650. In this system, a dye donor sheet containing a dynamic release layer overcoated with an ablative carrier topcoat is used, and the image is transferred to another adjacently aligned receiving sheet. For this reason, there has been a problem that a sheet that has become unnecessary after image recording becomes a waste material. Also in this case, a high-output laser was indispensable to enhance the transfer efficiency. As described above, the conventional thermal recording method using laser ablation requires a high-output laser, and has a problem that dust and waste materials cannot be avoided.

[0005] On the other hand, as a thermal recording method without ablation using a laser, a system called "dry silver" has been developed as disclosed in JP-A-6-194.
No. 781, etc. In this system, laser recording is performed on a recording material containing a silver source that can be thermally reduced, a reducing agent for silver ions, and a photothermal conversion dye. This was insufficient for practical performance.

Further, as another thermal recording method using a laser, US Pat. Nos. 4,602,263 and 4,826,976 describe compounds whose absorption changes due to thermal decomposition of carbamate. , 5th and 2nd
No. 43,052 describes a compound which develops yellow color by thermal decomposition of a t-butoxycarbonyl group introduced into a hydroxyl group. These methods utilize an irreversible single-molecule reaction, and are preferable for recording images in an extremely short time using a laser. However, the sensitivity is insufficient and further enhancement of sensitivity is desired. Sensitivity can be increased by coexistence of an acid catalyst, but storage stability is a problem.

As a method for forming a UV mask image (360 nm to 420 nm; corresponding to an exposure light source for a PS plate) commonly used for plate making materials, no practical proposal has been made in a heat mode system using a laser.

On the other hand, US Pat. No. 5,286,612,
Nos. 5,395,736 and 5,441,850
Nos. 8-503081 and 8-503082 disclose compounds which generate a superacid having a pKa <0 by the action of actinic radiation and a secondary acid generator which generates a secondary acid in the presence of a superacid. ,
And a recording material containing a compound that changes color upon contact with a secondary acid. Although this method is an effective method in terms of increasing the sensitivity of a recording material, the generation of a secondary acid from a secondary acid generator described in the patent is catalyzed only by a super strong acid generated from a super strong acid precursor. Things,
According to the patent publication, the decomposition of about 20 molecules of the secondary acid precursor per 1 molecule of the super-strong acid is catalyzed,
Since the generated secondary acid has no catalytic ability, it cannot be expected to increase the sensitivity by so-called rat-based acid multiplication.

Further, as a compound which proliferates an acid by the action of an acid, K. Asahi. Ichimura, Chem. Lett.
551 (1995), JP-A-8-248561, and the like, describe a compound that generates an organic acid by decomposition with an acid catalyst. The compound is defined as a substance that changes its structure by the action of a photoacid generator and an acid. An acid-reactive polymer composition used in combination is described. However,
In the document, by the action of the acid generated by the photoacid generator,
It is intended for a so-called photoresist that causes a structural change of being solubilized or insolubilized in a polar solvent or an aqueous alkaline solution, and there is no description about a recording material utilizing an absorption change. As a result of intensive studies on the compounds developed by Ichimura et al.
It has been found that the compound reported by imura et al. functions as a thermal acid generator, functions as an acid generator without newly adding light or a thermal acid generator, and can be used for image formation.

[0010]

SUMMARY OF THE INVENTION It is a first object of the present invention to provide a novel polymer which develops (or decolorizes) only by the action of a catalytic amount of acid or heat. A further object of the present invention is to perform recording with a low-output laser that has high thermal sensitivity and does not cause ablation even when a heat mode image recording method using a laser is used (especially 360 which is indispensable as a mask film for plate making). It is an object of the present invention to provide a novel image recording medium which can perform image recording corresponding to .about.420 nm, does not require a separate image receiving sheet, and has excellent storage stability.

[0011]

The object of the present invention has been attained by the present invention of the following (1) to (14). (1) A function of generating an acid by the action of an acid, a function of growing the acid by the action of the acid generated by itself and / or a function of generating an acid by heat, and a function of 360 to 900 n by the action of the acid
An image recording medium containing a polymer containing at least one or more ethylenically unsaturated monomers having a function of causing a change in the absorption range of m as a polymerization component.

(2) The image recording medium according to the above (1), wherein the polymer is a compound represented by the following general formula (1).

[0013]

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(In the formula (1), A represents a function of generating an acid by the action of an acid, and further, a function of generating an acid by the action of an acid generated by itself and / or a function of generating an acid by heat; Represents a repeating unit obtained by polymerization of at least one or more ethylenically unsaturated monomers having a function of causing a change in the absorption range of 360 to 900 nm by the action of B, and B represents at least one or more types of copolymerizable with A. Represents a repeating unit obtained by polymerization of an ethylenically unsaturated monomer, x and y represent mol%,
<X ≦ 100, x + y = 100. )

(3) The polymer according to the above (2), wherein A in the general formula (1) contains a compound represented by the following general formula (2) or (3) as a partial structure. .

[0016]

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(In the formula (2), R ¹ represents an electron-withdrawing group having a Hammett σp value larger than 0, R ² represents an alkyl group or an aryl group, and R ³ represents a hydrogen atom having a β-position hydrogen atom.
X represents a tertiary or tertiary alkyl group, and X represents a residue of an acid represented by XOH. )

[0018]

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(In the formula (3), P represents a substituent removed by the action of heat or an acid. W represents an oxygen atom, a sulfur atom,
Represents an —N (R ¹³ ) — group or a —C (R ¹⁴ ) (R ¹⁵ ) — group. R ¹³ , R ¹⁴ and R ¹⁵ each represent a hydrogen atom or a substituent. L represents a linking group. R ¹¹ and R ¹² represent a hydrogen atom or a substituent, and R ¹¹ and R ¹² may be the same or different, and R ¹¹ and R ¹² may combine to form a ring. X has the same meaning as in formula (2). )

(4) The image recording medium according to any one of (1) to (3), further comprising an acid generator that generates an acid by the action of light or heat. (5) The image recording medium according to any one of the above (1) to (3), further comprising an acid generator that generates an acid by heat and an infrared absorbing substance.

(6) An image recording method characterized by scanning and exposing the image recording medium according to any one of the above (1) to (5) with a laser beam. (7) An image recording method characterized by scanning and exposing the image recording medium according to any of the above (1) to (5) with a laser beam, and then heating the entire surface in a temperature range of 60 to 150 ° C.

(8) At least one kind of ethylenically unsaturated monomer having a portion having a function of generating an acid by the action of heat and a partial structure causing a change in an absorption region of 360 to 900 nm by the action of an acid. An image recording medium comprising a polymer obtained by polymerization. (9) The image recording medium according to the above (8), further comprising an acid generator that generates an acid by the action of light or heat.

(10) The image recording medium according to the above (8), wherein the polymer is a polymer represented by the general formula (1). (11) wherein A in the general formula (1) is a repeating unit obtained by polymerization of an ethylenically unsaturated monomer having a partial structure represented by the general formula (2) or (3). The image recording medium according to the above (10). (12) The above characterized by containing an infrared absorbing material
The image recording medium according to any one of (8) to (11).

(13) An image recording method comprising scanning and exposing the image recording medium according to any one of the above (8) to (12) with a laser beam. (14) After scanning and exposing the image recording medium according to any one of the above (8) to (12) with a laser beam, 60 ° C to 150 ° C
An image recording method, wherein the entire surface is heated in the temperature range described above.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. A in the general formula (1) has a function of generating an acid by the action of an acid, further multiplying the acid by the action of the acid generated by itself, and / or a function of generating an acid by heat, and a function of 360 by the action of the acid. It represents a repeating unit obtained by polymerization of at least one or more ethylenically unsaturated monomers having a function of causing a change in the absorption range of up to 900 nm. Among these functions, a function of generating an acid by the action of an acid and a function of multiplying the acid by the action of the acid generated by itself, and / or
Alternatively, as the compound having a function of generating an acid by heat, Chemistry Letter, p. 551 (1
995) and JP-A-8-248561.
Alternatively, cyclohexyl sulfonate and the like can be mentioned.

When the polymer having a thermal acid generating function of the present invention is applied to a laser heat mode type image recording medium, it is useful because it is not necessary to add an acid generator separately. A preferred form of A having such a function is a repeating unit containing, as a partial structure, a compound represented by formula (2) or (3).

In the general formula (2), R ¹ is an electron-withdrawing group having a Hammett σp value larger than 0 (having a carbon number of 0 to 60).
Is preferable). Specifically, an acyl group (eg, acetyl group, benzoyl group), a sulfonyl group (eg, methanesulfonyl, benzenesulfonyl), a heterocyclic group (eg, benzothiazolyl group, benzoxazolyl group), an aryl group (eg, phenyl, naphthyl), Represents an alkyl group having an electron-withdrawing group (for example, a trifluoromethyl group). These may further have a substituent. R ² is an alkyl group (including those having a substituent.
60 is preferred. For example, methyl group, ethyl group, iso-
A propyl group, a t-butyl group, a trifluoromethyl group, an ethoxymethyl group, etc., or an aryl group (including those having a substituent. The number of carbon atoms is preferably from 6 to 60. For example, a phenyl group, a naphthyl group, a 4-chlorophenyl) Group, 2-methoxyphenyl group, 4-nitrophenyl group, 3-methanesulfonylphenyl group, etc.). R ³ is a secondary or tertiary alkyl group having a hydrogen atom at the β-position (including those having a substituent. The number of carbon atoms is preferably 3 to 60. For example, t
-Butyl group, cyclohexyl group, tetrahydropyranyl group, tetrahydrofuranyl group, 4,5-dihydro-2-
Methylfuran-5-yl group, 2-cyclohexenyl group, etc.). R ³ is preferably a tertiary alkyl group.

X is a residue of an acid represented by XOH (pKa of XOH is preferably 3 or less. For example, p-toluenesulfonic acid, benzenesulfonic acid, methanesulfonic acid, polyvinylbenzenesulfonic acid, p-nitro Benzoic acid).

Next, the compound represented by formula (3) will be described. W represents an oxygen atom, a sulfur atom, -N (R ¹³⁾ -
Represents a group, —C (R ¹⁴ ) (R ¹⁵ ) —. R ¹³ , R ¹⁴ , R
¹⁵ represents a hydrogen atom or a substituent, and examples of the substituent include an alkyl group (eg, methyl, ethyl, isopropyl, t-butyl, octyl) and an aryl group (eg, phenyl, naphthyl).

The substituent P removed by the action of heat or an acid is introduced into a nucleophilic group such as a hydroxyl group, a mercapto group, an amino group, or a carbon atom, and after the substituent P is decomposed or released by the action of heat or an acid. An acid is generated by an intramolecular nucleophilic substitution reaction. As a useful substituent represented by P, when W is an oxygen atom, an alkoxycarbonyl group (for example, t-butoxycarbonyl group, isopropyloxycarbonyl group,
-Phenylethoxycarbonyl group, 1,1-diphenylethoxycarbonyl group, 2-cyclohexeneoxycarbonyl group, etc.), alkoxymethyl group (for example, methoxymethyl group, ethoxymethyl group, n-octyloxymethyl group, tetrahydropyranyl group, tetrahydrofuran) Nyl group, 4,5-dihydro-2-methylfuran-5-yl group, etc.), silyl group (for example, trimethylsilyl group, triethylsilyl group, t-butyldimethylsilyl group, t-butyldiphenylsilyl group, phenyldimethylsilyl group) etc),
And a secondary or tertiary alkyl group having a hydrogen atom at the β-position (eg, a t-butyl group, a 2-cyclohexenyl group, etc.) and the like.

When W is a sulfur atom, an alkoxymethyl group (eg, isobutoxymethyl group, tetrahydropyranyl group, etc.), an alkoxycarbonyl group (eg, benzyloxycarbonyl group, p-methoxybenzyloxycarbonyl group, etc.), an acyl group Preferred examples include a group (eg, acetyl group, benzoyl group, etc.) and a benzyl group (eg, p-methoxybenzyl group, bis (4-methoxyphenyl) methyl group, triphenylmethyl group, etc.). W
Is a nitrogen atom, an alkoxycarbonyl group (for example, t-butoxycarbonyl group, cyclohexyloxycarbonyl group, 2- (2-methyl) butoxycarbonyl group, 2- (2-phenyl) propyloxycarbonyl group, 2-chloro Preferred examples include an ethoxycarbonyl group and the like, an acyl group (for example, an acetyl group, a benzoyl group, a 2-nitrobenzoyl group, a 4-chlorobenzoyl group and a 1-naphthoyl group) and a formyl group. When W is a carbon atom, a tertiary alkoxycarbonyl group (such as a t-butoxycarbonyl group) is a preferred example.

L represents a linking group, and L is preferably selected such that at least one of the chain lengths connecting W and C in the general formula (3) is 3 to 8, and more preferably 3 to 4. L is selected so that In the intramolecular nucleophilic substitution reaction following the removal of these substituents, a form in which a 5- to 10-membered ring is formed is preferable, and a 5- or 6-membered ring is particularly preferable.

Specific examples of the structure having an acid generating function in A of the general formula (1) are shown below. The compound can be introduced into the monomer molecule by bonding at any of the substitutable positions of these compounds. The present invention is not limited to these. These compounds are disclosed in JP-A-8-2.
It can be synthesized in the same manner as in the method described in Japanese Patent Application No. 48561 or Japanese Patent Application No. 10-250051.

[0034]

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[0035]

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[0036]

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[0037]

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[0038]

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[0039]

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[0040]

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[0041]

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[0042]

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[0043]

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A in the general formula (1) also has a function of causing a change in the absorption range from 360 to 900 nm by the action of an acid. Examples of the partial structure that causes a change in the absorption region by the action of an acid include a basic leuco dye structure conventionally known as a heat-sensitive recording material and at least one amino group substituted with a substituent that decomposes or leaves under the action of an acid. Having at least one structure that causes a change in the absorption region by the removal of the substituent and at least one hydroxyl group substituted by a substituent that decomposes or leaves under the action of an acid; Structures that cause a change. In the present invention, any of these is useful, but preferably has a structure in which the absorption region is changed by the removal of a substituent of an amino group or a hydroxyl group by the action of an acid.

Examples of the substituent of such an amino group include an alkoxycarbonyl group (for example, t-butoxycarbonyl group, cyclohexyloxycarbonyl group, 2- (2-methyl) butoxycarbonyl group, 2- (2-phenyl) propyloxycarbonyl Groups, 2-chloroethoxycarbonyl group, etc.), an acyl group (for example, acetyl group, benzoyl group, 2-nitrobenzoyl group, 4-chlorobenzoyl group, 1-naphthoyl group, etc.) or formyl group. In the present invention, an alkoxycarbonyl group having a hydrogen atom at the β-position is particularly useful from the viewpoint of storage stability and heat sensitivity. Leuco dyes having such a substituent include U.S. Pat. No. 4,602,263,
No. 4,826,976 describes an example.

As the substituent of the hydroxyl group which is decomposed or eliminated by the action of an acid, a secondary or tertiary alkoxycarbonyl group having a hydrogen atom at the β-position (for example, t-butoxycarbonyl group, isopropyloxycarbonyl group, 1-
Phenylethoxycarbonyl group, 1,1-diphenylethoxycarbonyl group, 2-cyclohexeneoxycarbonyl group, etc.), silyl group (for example, trimethylsilyl group, triethylsilyl group, t-butyldimethylsilyl group, t-
Butyldiphenylsilyl group, phenyldimethylsilyl group, etc.) and a secondary or tertiary alkyl group having a hydrogen atom at the β-position (eg, tetrahydropyranyl group, tetrahydrofuranyl group, 4,5-dihydro-2-methylfuran- 5-yl group, t-butyl group, 2-cyclohexenyl group, etc.). In the present invention, a secondary or tertiary alkoxycarbonyl group having a hydrogen atom at the β-position is particularly useful. Examples of leuco dyes having such a substituent are described in US Pat. No. 5,243,052 and the like.

Examples of compounds having a function of causing a change in the absorption range of 360 to 900 nm by the action of an acid are described below. The compound can be introduced into a monomer molecule by bonding at a substitutable place of any of these compounds. Note that the present invention is not limited to the following specific examples.

[0048]

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[0049]

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[0050]

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[0051]

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[0052]

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[0053]

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[0054]

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[0055]

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[0056]

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Specific examples of the ethylenically unsaturated monomer include, for example, compounds having a substituted or unsubstituted vinyl group. Examples of the substituent include an alkyl group (methyl, ethyl, butyl, decyl, isobutyl, etc.), an aryl group (phenyl, naphthyl, etc.), an alkoxycarbonyl group (methoxycarbonyl, octyloxycarbonyl,
Isopropoxycarbonyl, etc.), aryloxycarbonyl group (phenoxycarbonyl, naphthoxycarbonyl, etc.), carbamoyl group (carbamoyl, N-methylcarbamoyl, N, N-dimethylcarbamoyl, N-octylcarbamoyl, N-phenylcarbamoyl, N-methyl) -N-phenylcarbamoyl, etc.), a halogen atom (fluorine, chlorine, bromine, etc.), a cyano group, an acyl group (acetyl, hexanoyl, 2-methylpropanoyl, benzoyl, etc.), an acyloxy group (acetyloxy, benzoyloxy, etc.), Examples include an alkoxy group (methoxy, ethoxy, isopropoxy, octyloxy, etc.) and an aryloxy group (phenoxy, etc.). These substituents may be further substituted with a substitutable group. In the present invention, a compound having an acid generating function and / or a compound causing a change in the absorption band of 360 to 900 nm is bonded at any of the substitutable positions of these compounds.

Specific examples of the monomer component A in the polymer represented by the general formula (1) of the present invention are shown below, but the present invention is not limited thereto.

[0059]

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[0060]

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[0061]

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[0062]

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[0063]

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The monomer component A in the polymer represented by the general formula (1) of the present invention can be synthesized with reference to the references cited in the above description. Hereinafter, specific synthesis examples of the exemplary compound (M-1) will be described.

[0065]

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A mixture of 0.1 mol of the compound (1-A) (manufactured by Otsuka Chemical Co., Ltd.), 0.1 ml of nitrobenzene and 300 ml of tetrahydrofuran was cooled on ice, and 0.2 mol of an oil dispersion of sodium hydride was added thereto. After stirring for 30 minutes,
0.1 mol of compound (1-B) ｛The synthesis of compound (1-B) is described in J. G.
en. Chem. USSR, 33, 3099 (19
63), and reacted at room temperature for 3 hours. Then add 300 ml of ethyl acetate and 300 ml of water,
After separating the aqueous layer, the organic layer was further washed with water and brine. After concentrating the organic layer, the residue was purified by silica gel column chromatography (eluent: ethyl acetate / hexane = 1/4) to obtain compound (1-C) in a yield of 52%.

Next, 0.05 mol of the compound (1-C) was placed in 300 ml of ethanol and cooled with ice. Thereto was added a mixture of 10 ml of water and 0.1 ml of ethanol in which 0.1 ml of nitrobenzene and 0.075 mol of sodium hydroxide were dissolved, and the mixture was stirred for 5 hours. After that, most of the ethanol was distilled off under reduced pressure,
200 ml of ethyl acetate and 100 ml of water were added thereto, and the aqueous layer was separated. The organic layer was further washed with water and brine, and then the organic layer was concentrated to obtain a crude compound (1-D).

The crude product of the compound (1-D) thus obtained was directly dissolved in 200 ml of methylene chloride, and 0.15 mol of the compound (1-F) and 0.075 mol of the compound (1-E) were added thereto.
0.1 ml of nitrobenzene was added and stirred for 4 hours. Thereafter, the reaction solution was washed with water and concentrated, and the obtained residue was purified by silica gel column chromatography (eluent; ethyl acetate / hexane = 1/3) to give Exemplified Compound (M-1) as 1
Obtained in 2% yield.

B in the general formula (1) represents a repeating unit obtained by polymerizing at least one kind of vinyl monomer capable of forming a copolymer with A, and the polarity, glass transition temperature and the like are adjusted. Thus, storage stability, coloring activity and the like can be controlled.
Such vinyl monomers may be used in combination of two or more. Preferred examples include acrylate, methacrylate, acrylamide, styrene, vinyl ether and the like. Specific examples of the monomer forming B are shown below, but the present invention is not limited thereto.

[0070]

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[0071]

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[0072]

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[0073]

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[0074]

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[0075]

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[0076]

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In the general formula (1), x and y are mo
Represents l%. x and y each satisfy 0 <x ≦ 100, preferably 1 ≦ x <100, and x + y = 100. x
Is more preferably 30 or more, and still more preferably 50 or more. A and B in the polymer may each be one type or two or more types.

The molecular weight of the polymer represented by the general formula (1) is preferably in the range of 1,000 to 1,000,000, particularly preferably in the range of 2,000 to 200,000. The polymer may be in any form such as a random copolymer, an alternating copolymer and a block copolymer, but a random copolymer which is easily synthesized is generally used.

Preferred combinations of monomers forming A and B and x and y in the polymer represented by the general formula (1) are shown below, but the present invention is not limited thereto.

[0080]

[Table 1]

[0081]

[Table 2]

The polymer of the present invention can be synthesized by various polymerization methods such as solution polymerization, precipitation polymerization, suspension polymerization, bulk polymerization,
It can be carried out by emulsion polymerization. The method of initiating polymerization includes a method using a radical initiator, a method of irradiating light or radiation, and the like. These polymerization methods and the method of initiating the polymerization are described in, for example, T. Tsuruta, “Polymer Synthesis Method” Revised Edition (Nikkan Kogyo Shimbun, 1971), Takatsu Otsu, Masayoshi Kinoshita, “Experimental Method of Polymer Synthesis” Published in 1972,
It is described on pages 124-154.

Among the above polymerization methods, a solution polymerization method using a radical initiator is particularly preferred. Solvents used in the solution polymerization method include, for example, ethyl acetate, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, acetone, dioxane, N, N-dimethylformamide, N, N-dimethylacetamide, benzene, toluene , Acetonitrile, methylene chloride, chloroform, dichloroethane, or a mixture of two or more of various organic solvents, or a mixed solvent with water.

The polymerization temperature must be set in relation to the molecular weight of the polymer to be produced, the type of initiator, and the like, and can be from 0 ° C. or lower to 100 ° C. or higher.
Polymerization is carried out in the range of 0 ° C. More preferably, 30 to 85
The polymerization is performed in a temperature range of ° C.

Examples of the radical initiator used in the polymerization include 2,2′-azobisisobutyronitrile,
Such as 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2-amidinopropane) dihydrochloride, and 4,4'-azobis (4-cyanopentanoic acid) Preferred are azo-based initiators and peroxide-based initiators such as benzoyl peroxide, t-butyl hydroperoxide, and potassium persulfate (for example, it may be used as a redox initiator in combination with sodium bisulfite). In the present invention, an initiator (for example, 2,2'-azobis (2,4-dimethylvaleronitrile)) and a 2,2'-azobis (4-methoxy-2,
4-dimethylvaleronitrile), dimethyl 2,2'-azobis (2-methylpropionate), 2,2'-azobis [2- (3,4,5,6-tetrahydropropane)
Dihydrochloride] and the like are particularly preferred.

The amount of the polymerization initiator used can be adjusted according to the polymerizability of the monomer and the required molecular weight of the polymer, but is in the range of 0.01 to 5.0 mol% based on the monomer. Is preferred. In the synthesis of the polymer of the present invention, A
The monomers forming B and B may be mixed and placed in a reaction vessel first, and the initiator may be charged, or the polymerization may be carried out through a process of dropping these monomers into a polymerization solvent.

The following are typical examples of the synthesis of the copolymer of the present invention. Synthesis Example 1 Synthesis of Exemplified Compound (P-1) 0.05 mol of Compound (M-1) and Compound (E-1)
Dissolve 0.05 mol in 50 ml of benzene and add 2,2'-
Azobis (2,4-dimethylvaleronitrile) 200 m
g was added and heated and stirred at 60 ° C. for 10 hours. The reaction solution was poured into MeOH (500 ml) to obtain a white polymer [exemplified compound (P-1)]. 82% yield. ¹ H
NMR confirmed that it was a copolymer of compound (M-1) and compound (E-1). X: y from elemental analysis
= 50: 50.

Synthesis Example 2 Synthesis of Exemplified Compound (P-2) 0.05 mol of the compound (M-1) was dissolved in 50 ml of benzene, and 200 mg of 2,2'-azobis (2,4-dimethylvaleronitrile) was added thereto. The mixture was heated and stirred at 60 ° C. for 10 hours. The reaction solution was poured into MeOH (500 ml) to obtain a white polymer [Exemplary Compound (P-2)].
86% yield.

The image recording medium of the present invention is generally produced by coating a polymer represented by the general formula (1) on a support. When the polymer of the present invention also has a function of generating an acid by heat, a change in the absorption region alone occurs only by the action of heat.
Excellent sensitivity and image cutting. Further, the image recording medium of the present invention does not require the use of a so-called binder, and thus has the advantages that the film thickness can be reduced, a sharp image can be obtained, and abrasion does not easily occur.

In the present invention, a small amount of a base may be added for the purpose of enhancing the storage stability of the image recording medium, or a compound capable of generating an acid by the action of light or heat may be added for the purpose of enhancing the sensitivity. Various additives such as a pigment, an antioxidant, and an anti-sticking agent can be added according to the requirements. Further, an overcoat layer may be provided to protect the image recording layer, or a backcoat layer may be provided on the back surface of the support. Various known techniques for heat-sensitive recording materials can be used, such as providing a single layer or a plurality of undercoat layers made of pigment or resin between the image recording layer and the support.

When a base is added, an organic base is preferred. For example, a guanidine derivative (for example, 1,3-diphenylguanidine, 1,3-dimethylguanidine, 1,3-
Dibutylguanidine, 1-benzylguanidine, 1,
1,3,3-tetramethylguanidine, etc.), aniline derivatives (eg, aniline, pt-butylaniline, N,
N′-dimethylaniline, N, N′-dibutylaniline, triphenylamine, etc.), alkylamine derivatives (eg, tributylamine, octylamine, laurylamine, benzylamine, dibenzylamine, etc.), and heterocyclic compounds (eg, N , N'-Dimethylaminopyridine, 1,8-diazabicyclo [5.4.0] -7-
Undecene, triphenylimidazole, lutidine, 2
-Picoline) is a preferred example. These bases are used in an amount of from 1 to
It is preferable to add 50 mol%, particularly preferably 5 to 20 mol%.

The compound capable of generating an acid by the action of light or heat is a compound which is not an acid in nature but is a compound capable of generating an acid upon irradiation with light or heating. For example, a compound described in JP-A-4-162040 or Diazonium, ammonium, iodonium, sulfonium,
Examples thereof include sulfonates, PF ⁶ -salts, AsF ⁶ -salts, and SbF ⁶ -salts of aromatic onium compounds such as phosphonium. These compounds are preferably added in an amount of 1 to 50 mol%, particularly preferably 1 to 20 mol%, based on the position A in the polymer.

When a pigment is added, examples include diatomaceous earth, talc, kaolin, calcined kaolin, titanium oxide, silicon oxide, magnesium carbonate, calcium carbonate, aluminum hydroxide, and urea-formalin resin.

Other additives include ultraviolet absorbers such as benzophenone type and benzotriazole type, head wear and sticking preventives comprising higher fatty acid metal salts such as zinc stearate and calcium stearate, paraffin, paraffin oxide, polyethylene, Waxes, such as polyethylene oxide and caster wax, are mentioned, and can be added as needed.

As the support used in the image recording medium of the present invention, papers such as high quality paper, baryta paper, coated paper, cast coated paper, synthetic paper, polyethylene, polypropylene, polyethylene terephthalate, polyethylene-2,
6-naphthylene dicarboxylate, polyarylene,
Examples thereof include polymer films such as polyimide, polycarbonate, and triacetyl cellulose, glass, metal foil, and nonwoven fabric. In the case where the image recording medium of the present invention is used for a transmission type image such as an OHP film or a plate making film, a transparent support is used. For a plate making film, a support having a small coefficient of thermal expansion and good dimensional stability and having no absorption in the photosensitive region of the PS plate is selected.

In the image recording medium of the present invention, as a heating method as an image forming means, a method of contacting with a heated block or plate, a method of contacting with a heat roller or a heat drum, a halogen lamp or an infrared or infrared There are a method of irradiating an infrared lamp heater, a method of imagewise heating with a thermal head of a thermal printer, and a method of irradiating a laser beam. The image recording medium of the present invention is used for plate making materials,
In the case where a high resolution is required, a method of scanning and exposing with a laser beam is preferable. In order to form an image with less heat energy, the heat-sensitive recording material of the present invention can be heated to an appropriate temperature in advance.
In the present invention, after imagewise heating by these methods, 60
The image can be amplified by heating the entire surface at a temperature of １５０150 ° C. (preferably 60 to 120 ° C.).

When an image is formed by irradiating a laser beam, a dye that absorbs light having the wavelength of the laser beam must be present in order to convert the laser beam into heat energy. Excimer laser, argon laser, helium neon laser, semiconductor laser, glass (YAG) laser, carbon dioxide laser,
Although there is a dye laser and the like, a helium neon laser, a semiconductor laser and a glass laser are laser light sources useful in the present invention. Among them, a semiconductor laser is particularly useful because the device is small and inexpensive. The oscillation wavelength of the semiconductor laser is usually 670 to 830 nm, and a dye having absorption in the near infrared is used. As the near-infrared absorbing dye, a cyanine dye, a squarylium dye, a merocyanine dye, an oxonol dye, a phthalocyanine dye, and the like are used. Specific examples thereof include, for example, U.S. Pat. Nos. 4,973,572, 4,948,777, 4,950,640, and 4,950,639.
Nos. 4,948,776 and 4948,778, 4,942,141, 4,952,552, 5,036,040 and 4,912,083.
And the like.

When a compound that generates an acid by light is used, a laser is selected as a means for forming a latent image in accordance with the absorption characteristics of the photoacid generator. At this time, various dyes may be added for the purpose of spectral sensitization, but in that case, it is necessary to select a laser according to the absorption wavelength of the dye.

[0099]

The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto.

Example 1 The following compounds were dissolved in chloroform, and
μm polyethylene terephthalate film,
It dried and produced the transparent recording sheet (samples 1-6).
As comparative samples, recording sheets (samples 7 and 8) coated with a low-molecular material were prepared.

Sample-1 Polymer (P-1) Leuco dye part 2 mmol / m ² IR dye 100 mg / m ² Sample-2 Polymer (P-2) Leuco dye part 2 mmol / m ² IR dye 100 mg / m ²

Sample-3 Polymer (P-4) Leuco dye part 2 mmol / m ² IR dye 100 mg / m ² Sample-4 Polymer (P-11) Leuco dye part 2 mmol / m ² IR dye 100 mg / m ²

Sample-5 Polymer (P-16) Leuco dye part 2 mmol / m ² IR dye 100 mg / m ² Sample-6 Polymer (P-17) Leuco dye part 2 mmol / m ² IR dye 100 mg / m ²

Sample-7 Compound C- (2) 2 mmol / m ² Compound D- (47) 2 mmol / m ² IR dye 100 mg / m ² Polystyrene (3000 mer, Wako Pure Chemical Industries) 2.2 g / m ²

Sample-8 Compound C- (2) 2 mmol / m ² Compound D- (64) 2 mmol / m ² IR dye 100 mg / m ² Polystyrene (3000 mer, Wako Pure Chemical Industries) 2.2 g / m ²

[0106]

Embedded image

<Laser Exposure Conditions for Image Recording> Sp
ectra Diode Labs No.SDL-2430 (wavelength range: 800-8
30 nm) to obtain an output of 400 mW.
An image writing laser was used. Using this laser, a beam system of 160 μm and a laser scanning speed of 1.
25m / sec (scan center), sample feed speed 15m
m / sec, the scanning pitch is set to 8 lines / mm,
Exposure to give a × 9 mm image was performed on the sample described above. At this time, the laser energy density on the sample was ² mJ / mm ² .

<Evaluation of Image Forming Efficiency> After each sample was exposed to laser, it was subjected to thermal development under heating conditions of 120 ° C. and 60 seconds.
Find the maximum color density at the laser scanning center (image part),
The image forming efficiency (coloring ratio) was calculated from the comparison with the theoretical value when 100% color was formed.

<Evaluation of Storage Property> Each coated sample was stored at 60 ° C./70% humidity for 7 days, and then the film absorption was measured. The ratio of color development during storage from the absorption spectrum was defined as the decomposition rate and used as a measure of storage stability.

<Evaluation of Fogging> Each coated sample was heat-developed under a heating condition of 120 ° C. for 60 seconds without laser exposure without exposure to a laser beam. It was a measure of fog. Table 3 shows the obtained results.

[0111]

[Table 3]

From Table 3, it is clear that the compound of the present invention develops a good color without adding a thermal acid generator, and that the polymer itself has a function as a thermal acid generator. In addition, it is possible to greatly improve the color developability without deteriorating the storage stability and fog by polymerizing the material,
The utility of the present invention is clear.

[0113]

According to the present invention, it is possible to obtain a novel polymer which develops (or decolorizes) only by the action of a catalytic amount of acid or heat. Furthermore, by using the above-mentioned polymer, high thermal sensitivity is achieved, and recording with a low-output laser that does not cause ablation even when a heat mode image recording method using a laser is used (especially indispensable as a mask film for plate making) (An image recording corresponding to 360 to 420 nm) is possible, and a new image recording medium which does not require a separate image receiving sheet and has excellent storage stability can be obtained.

Continued on the front page (72) Inventor Tatsuhiko Obayashi 210 Nakanakanuma, Minamiashigara-shi, Kanagawa Prefecture Fuji Photo Film Co., Ltd. F-term (reference) 2H026 AA07 AA24 BB24 BB48 DD01 DD53

Claims (14)

[Claims] (1) a function of generating an acid by the action of an acid, a function of growing an acid by the action of an acid generated by itself, and / or a function of generating an acid by heat;
An image recording medium containing a polymer containing, as a polymerization component, at least one or more ethylenically unsaturated monomers having, in a molecule, a function of causing a change in an absorption range of 60 to 900 nm. 2. The image recording medium according to claim 1, wherein said polymer is a compound represented by the following general formula (1). Embedded image (In the formula (1), A has a function of generating an acid by the action of an acid, further multiplying the acid by the action of the acid generated by itself, and / or a function of generating an acid by heat, and a function of the acid. A represents a repeating unit obtained by polymerization of at least one or more ethylenically unsaturated monomers having a function of causing a change in the absorption range of 360 to 900 nm, and B represents A
Represents a repeating unit obtained by the polymerization of at least one or more ethylenically unsaturated monomers copolymerizable with x and y, and x and y represent mol%, and 0 <x ≦ 10, respectively.
0, x + y = 100. ) 3. In the general formula (1), A represents the following general formula:
The compound represented by the formula (2) or the general formula (3)
3. The poly according to claim 2, which is contained as a product.
Mar. Embedded image(In the formula (2), R¹Is Hammett's σp value greater than 0
Represents an electron-withdrawing group;^TwoIs an alkyl or aryl group
And R^ThreeIs a secondary or tertiary having a hydrogen atom at the β-position
X represents an alkyl group, and X represents a residue of an acid represented by XOH.
You. )(In the formula (3), P is removed by the action of heat or an acid.
Represents a substituent. W is an oxygen atom, a sulfur atom, -N (R¹³)
-Group or -C (R¹⁴) (R^Fifteen)-Represents a group. R ¹³, R¹⁴
And R^FifteenRepresents a hydrogen atom or a substituent, respectively. L
Represents a linking group. R¹¹And R¹²Is a hydrogen atom or substitution
R represents a group¹¹And R¹²Are the same or different
Good and R¹¹And R¹²May combine to form a ring.
X has the same meaning as in formula (2). ) 4. The image recording medium according to claim 1, further comprising an acid generator that generates an acid by the action of light or heat. 5. The method according to claim 1, further comprising an acid generator that generates an acid by heat and an infrared absorbing substance.
An image recording medium according to any one of the above. 6. An image recording method, comprising scanning and exposing the image recording medium according to claim 1 with a laser beam. 7. After scanning and exposing the image recording medium according to any one of claims 1 to 5 with a laser beam, 60 to 1
An image recording method, wherein the entire surface is heated in a temperature range of 50 ° C. 8. Polymerization of at least one or more ethylenically unsaturated monomers having a portion having a function of generating an acid by the action of heat and a partial structure which causes a change in an absorption range of 360 to 900 nm by the action of an acid. An image recording medium characterized by containing the polymer obtained in (1). 9. The image recording medium according to claim 8, further comprising an acid generator that generates an acid by the action of light or heat. 10. The image recording medium according to claim 8, wherein the polymer is a polymer represented by the general formula (1) according to claim 2. 11. A in the general formula (1) is a repeating unit obtained by polymerization of an ethylenically unsaturated monomer having a partial structure represented by the general formula (2) or (3) according to claim 3. The image recording medium according to claim 10, wherein: 12. The image recording medium according to claim 8, further comprising an infrared absorbing material. 13. An image recording method, comprising scanning and exposing the image recording medium according to claim 8 to a laser beam. 14. After scanning and exposing the image recording medium according to claim 8 with laser light,
An image recording method, wherein the entire surface is heated in a temperature range of from 150C to 150C.