JP2005262150A - Microcapsule, production method for the same, and recording material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a production method for microcapsules by which the fluctuation of particle diameter and the fluctuation of heat sensitivity of a heat sensitive recording material are prevented. <P>SOLUTION: The microcapsule production method involves formation of microcapsule walls by emulsifying a solution containing (1) oil-phase components containing at least an oil-soluble core substance to be encapsulated in the microcapsules, a microcapsule wall precursor, and a hydrophobic organic solvent and (2) water-phase components containing either water or water with a water-soluble protection colloid having a weight average molecular weight of 2,000 or lower and/or a surfactant having a weight average molecular weight of 2,000 or lower, and carrying out interface polymerization reaction of the emulsion. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a microcapsule that can be suitably used for a recording material, a manufacturing method thereof, and a recording material using the microcapsule.

  Thermal recording materials that are widely used as recording media such as facsimiles and printers mainly use materials obtained by applying a solid dispersion of an electron-donating dye precursor on a support and drying it. The recording method using an electron donating dye precursor has the advantage that the material is easily available and exhibits high color density and color development speed, but it is easy to develop color due to storage conditions after recording, heating or adhesion of a solvent, etc. However, there are problems with the storability and reliability of recorded images, and many improvements have been studied.

  As one method for improving the storability of a recorded image, an electron donating dye precursor is encapsulated in a microcapsule, and the developer and the dye precursor are separated from each other in the recording layer. A method for improving the storage stability has been proposed. By this method, high color developability and image stability can be obtained.

  As other heat-sensitive recording materials, so-called diazo-type heat-sensitive recording materials using a diazonium salt compound have been studied. This diazonium salt compound reacts with a phenol derivative or a compound having an active methylene group (coupler) to form a dye, but also has photosensitivity and loses its activity upon irradiation with light. Recently, a photo-fixing type thermosensitive recording material that can be applied to a thermosensitive recording material by using these properties to form an image by reacting a diazo compound and a coupler with heat, and then fixed by irradiation with light. (For example, refer nonpatent literature 1).

  However, since the recording material using the diazonium salt compound has high chemical activity, the diazonium salt compound and the coupler gradually react even at a low temperature, resulting in a short shelf life. As one solution to this problem, a method of including a diazonium salt compound in a microcapsule and isolating it from a coupler, water, or a basic compound has been proposed (for example, see Non-Patent Document 2).

  In addition, multicolor thermal recording materials have attracted attention as one application field of thermal recording materials. Reproduction of multicolor images by thermal recording has been said to be difficult compared to electrophotographic recording systems and ink jet recording systems, but in this regard, an electron-donating dye precursor and a developer are already mainly used on a support. It has been found that a multicolor thermosensitive recording material can be obtained by laminating two or more thermochromic layers containing a thermochromic layer or diazonium salt compound as a component and a coupler that reacts with the diazonium salt compound and develops color when heated. ing. In a multicolor thermosensitive recording material, in order to obtain excellent color reproducibility, it is essential to highly control the thermal color development characteristics of the microcapsules.

  Conventionally, in order to include an electron-donating dye precursor or a diazonium salt compound in a microcapsule, these compounds are generally dissolved in an organic solvent (oil phase) and then dissolved in an aqueous solution of a water-soluble polymer (aqueous phase). And emulsified and dispersed. At this time, a polymer wall is formed at the interface between the organic solvent phase and the aqueous phase by adding a monomer or prepolymer as a wall material to either the organic solvent phase side or the aqueous phase side, and microencapsulated. (For example, refer to Non-Patent Documents 3 and 4.) As the microcapsule wall to be formed, various materials such as gelatin, alginate, celluloses, polyurea, polyurethane, melamine resin, and nylon can be used. Polyurea and urethane resins have a glass transition temperature of about room temperature to 200 ° C., so that the capsule wall exhibits thermal responsiveness and is suitable for designing a heat-sensitive recording material.

  In the case of a microcapsule having a polyurethane or polyurea wall, the microcapsule is prepared by first dissolving a diazonium salt or an electron-donating dye precursor in an organic solvent, and adding a polyvalent isocyanate compound to the organic phase solution. Is emulsified in a water-soluble polymer aqueous solution. Thereafter, a method for forming a capsule wall by adding a catalyst for promoting a polymerization reaction to an aqueous phase or raising the temperature of an emulsion to polymerize a polyvalent isocyanate compound with a compound having active hydrogen such as water is conventionally known. ing. As the polyurea compound which is a material for forming the above polyurea or polyurethane wall, for example, an adduct of 2,4-tolylene diisocyanate and trimethylolpropane and an adduct of xylylene diisocyanate and trimethylolpropane are mainly used. (For example, refer to Patent Documents 1 and 2.)

However, according to such a conventional method, the capsules aggregate, the particle diameter with time changes, and when a thermosensitive recording material is produced using the produced microcapsules, there is a problem that the thermal sensitivity fluctuates. .
Japanese Unexamined Patent Publication No. Sho 62-212190 JP-A-4-26189 Koji Sato et al., “Journal of the Institute of Image Electronics Engineers”, Vol. 11, No. 4, 290-296, 1982, etc. Usami Tomomasa et al., “The Journal of Electrophotographic Society”, Vol. 26, No. 2, pp. 115-125, 1987 Asahi Kondo "Microcapsule", Nikkan Kogyo Shimbun, 1970 Kondo et al. “Microcapsules”, Sankyo Publishing, 1977

  Accordingly, an object of the present invention is to provide a microcapsule in which fluctuations in particle size of capsules over time and sensitivity changes associated therewith are suppressed, and a recording material using the same.

In view of such a situation, the present inventor conducted intensive research and found that the above-described problems can be solved by the following method, thereby completing the present invention.
That is, the present invention provides the following manufacturing method and the like.

<1> Next components (1) and (2)
(1) an oil phase component containing at least an oil-soluble core substance encapsulated in a microcapsule, a microcapsule wall precursor, and a hydrophobic organic solvent;
(2) water or a water phase component comprising water and a water-soluble protective colloid having a weight average molecular weight of 2000 or less and / or a surfactant having a weight average molecular weight of 2000 or less,
A method for producing a microcapsule comprising emulsifying a liquid composed of the above and forming a microcapsule wall by interfacial polymerization reaction.

  <2> The method for producing a microcapsule according to <1>, wherein the concentration of the protective colloid in the aqueous phase is 0 to 50% by mass of the total aqueous phase component.

  <3> The method for producing a microcapsule according to <1> or <2>, wherein the concentration of the surfactant in the aqueous phase is 0 to 50% by mass of the total aqueous phase component.

  <4> The method for producing a microcapsule according to <1>, <2> or <3>, wherein the microcapsule wall precursor is an isocyanate compound.

  <5> A compound (A) in which at least one of the isocyanate compounds has two or more isocyanate groups, a compound having one active hydrogen in the molecule and a weight average molecular weight of 500 to 20,000 ( <4> The method for producing a microcapsule according to <4>, which is a reaction product with B).

  <6> The method for producing a microcapsule according to <5>, wherein the compound (B) is a polyethylene oxide having a hydroxyl group at one end.

  <7> The method for producing a microcapsule according to <5> or <6>, wherein the compound (B) is a compound having a melting point of 40 to 180 ° C.

  <8> The proportion of the reaction product of the polyfunctional isocyanate (A) having two or more isocyanate groups and the compound (B) having one active hydrogen in the molecule is 10% by mass with respect to all isocyanate compounds. The manufacturing method of the microcapsule in any one of <5>-<7> which is -100 mass%.

<9> Reaction of polyfunctional isocyanate (A) having at least one isocyanate compound having two or more isocyanate groups and a polyether derivative (I) having a terminal amino group represented by the following general formula (I) The method for producing a microcapsule according to <4>, which is a product.

[Wherein, X represents —CO— or —SO ₂ —, A represents an arylene or alkylene group, L represents an alkylene group, and R represents an alkyl group, an aryl group or an acyl group. m represents 0 or 1, and n represents a number of 10 to 500 in terms of the average number of moles added of the polyether group. ]

<10> Polyfunctional isocyanate (A) having two or more isocyanate groups, and a polyether derivative having a terminal amino group represented by the following general formula (I) (I
<9> The manufacturing method of the microcapsule as described in <9> whose ratio of the reaction product with this is 10 mass%-100 mass% with respect to all the isocyanate compounds.

  <11> The method for producing microcapsules according to <9> or <10>, wherein the polyether derivative (I) is a compound having a melting point of 40 to 180 ° C.

  <12> The method for producing a microcapsule according to any one of <1> to <11>, wherein the particle size of the microcapsule is 0.1 μm to 1.6 μm.

  <13> The method for producing a microcapsule according to any one of <1> to <12>, wherein the core substance is a diazo compound or an electron donating dye precursor.

  <14> A microcapsule obtained by the production method according to any one of <1> to <13>.

  <15> A recording material comprising a recording layer containing a microcapsule containing a color forming component on a support, wherein the microcapsule is the microcapsule according to <14>.

  According to the production method of the present invention, it is possible to obtain a microcapsule in which the microcapsule has a small particle size variation with time, and accordingly, the change in thermal sensitivity of the recording material is suppressed.

The production method of the present invention comprises the following components (1) and (2)
(1) an oil phase component containing at least an oil-soluble core substance encapsulated in a microcapsule, a microcapsule wall precursor, and a hydrophobic organic solvent;
(2) water or a water phase component comprising water and a water-soluble protective colloid having a weight average molecular weight of 2000 or less and / or a surfactant having a weight average molecular weight of 2000 or less,
And a microcapsule wall is formed by an interfacial polymerization reaction.

[Microcapsule wall precursor]
The microcapsule wall precursor used in the present invention is preferably an isocyanate compound.
In particular, at least one of the isocyanate compounds is a polyfunctional isocyanate (A) having two or more isocyanate groups, and a compound (B) having one active hydrogen in the molecule and a weight average molecular weight of 500 to 20,000. It is preferable that it is a reaction product with.

Here, the polyfunctional isocyanate (A) having two or more isocyanate groups in the molecule will be described.
Among these, examples of the compound having two isocyanate groups in the molecule include m-phenylene diisocyanate, p-phenylene diisocyanate, 2,6-tolylene diisocyanate, 2,4-tolylene diisocyanate, and naphthalene-1,4. -Diisocyanate, diphenylmethane-4,4'-diisocyanate, 3,3'-dimethoxy-biphenyl diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, xylylene-1,4-diisocyanate, xylylene-1,3 -Diisocyanate, 4-chloroxylylene-1,3-diisocyanate, 2-methylxylylene-1,3-diisocyanate, 4,4'-diphenylpropane diisocyanate, 4,4'-diphenylhexafluoropropane diisocyanate , Trimethylene diisocyanate, hexamethylene diisocyanate, propylene-1,2-diisocyanate, butylene-1,2-diisocyanate, cyclohexylene-1,2-diisocyanate, cyclohexylene-1,3-diisocyanate, cyclohexylene-1,4 -Diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,4-bis (isocyanatemethyl) cyclohexane and 1,3-bis (isocyanatemethyl) cyclohexane, isophorone diisocyanate, lysine diisocyanate and the like. Furthermore, addition reaction products of these bifunctional isocyanate compounds with bifunctional alcohols such as ethylene glycols and bisphenols, and phenols can also be used.

  Furthermore, a polyfunctional isocyanate compound can also be used. As an example of such a compound, the above-mentioned bifunctional isocyanate compound is used as a main raw material, these trimers (burette or isocyanurate), and a polyfunctional adduct of a polyol such as trimethylolpropane and a bifunctional isocyanate compound. , Benzene isocyanate formalin condensate, polymers of isocyanate compounds having a polymerizable group such as methacryloyloxyethyl isocyanate, lysine triisocyanate, and the like can also be used. In particular, xylene diisocyanate and its hydrogenated product, hexamethylene diisocyanate, tolylene diisocyanate and its hydrogenated product are used as the main raw materials, and these trimers (burette or isosinurate) as well as adducts with trimethylolpropane are multifunctional. These are preferred. These compounds are described in “Polyurethane Resin Handbook” (edited by Keiji Iwata, published by Nikkan Kogyo Shimbun (1987)).

  Among these, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylylene-1,4-diisocyanate, xylylene-1,3-diisocyanate, trimethylolpropane and xylylene-1,4-diisocyanate or xylylene Adducts with -1,3-diisocyanate are preferred, especially xylylene-1,4-diisocyanate and xylylene-1,3-diisocyanate, trimethylolpropane and xylylene-1,4-diisocyanate or xylylene-1,3-diisocyanate The adduct of

  The compound (B) having one active hydrogen in the molecule and having a weight average molecular weight of 500 to 20,000 will be described. Examples of the functional group having active hydrogen include a hydroxyl group, an amino group, and a carboxyl group. Of these, a hydroxyl group and an amino group are particularly preferred. The compound having such active hydrogen and having a weight average molecular weight of 500 to 20,000 is not particularly limited. For example, polyether, polyester, polyamide, polyurea, polyurethane, polysiloxane, vinyl having active hydrogen at one end. Examples thereof include a polymer of monomers (hereinafter referred to as vinyl polymer). Of these, polyethers, polyesters, polysiloxanes, and vinyl polymers are preferred from the viewpoint of the solubility of the compound during encapsulation. If the weight average molecular weight is less than 500, fogging increases due to the introduction of these compounds. On the other hand, when the weight average molecular weight is larger than 20000, it becomes difficult to synthesize the compound, and since the viscosity becomes high, it becomes difficult to prepare liquid and form capsules during encapsulation. A preferable weight average molecular weight is 500-7000, and 1000-6000 are more preferable.

  More specifically, examples of the polyether include polyethylene oxide, polypropylene oxide, polytetramethylene oxide, polystyrene oxide, polycyclohexylene oxide, poly (ethylene thioglycol) and the like. Examples of the polyester include polycaprolactone. These compounds are obtained by ring-opening polymerization of a cyclic compound such as ethylene oxide or propylene oxide with an alcohol, alkoxide, carboxylic acid, carboxylate or the like as a polymerization initiation terminal, or with caprolactone or the like with an alcohol, alkoxide or the like as a polymerization initiation terminal. Obtained as a polyether or polyester having a hydroxyl group at the end. It is also possible to convert this terminal hydroxyl group into a terminal amino group, a carboxyl group or the like by a known reaction. Also usable are polyethers having active hydrogen at both ends, and compounds obtained by converting only one active hydrogen of a polyester into an ether group, an ethesul group or the like. As the polysiloxane, for example, a polydimethylsiloxane derivative having a hydroxyl group at one end can be used.

  Vinyl polymers (for example, poly (meth) acrylate, polystyrene, poly (meth) acrylamide, etc.) can also be used. Such a compound can be obtained as a vinyl polymer having a hydroxyl group and a carboxyl group at one end by radical polymerization of a vinyl monomer in the presence of a mercapto compound such as mercaptoethanol or mercaptoacetic acid and a radical polymerization initiator. If necessary, these functional groups can be converted to amino groups or the like using a known reaction. Examples of vinyl polymerization monomers include, for example, (meth) acrylic acid esters, such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, Butyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, chloroethyl (meth) acrylate, Allyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenyl (meth) acrylate -, Naphthyl (meth) acrylate, etc.),: (meth) acrylamides For example, (meth) acrylamide, N-alkyl (meth) acrylamide (the alkyl group includes, for example, methyl group, ethyl group, propyl group, butyl group, t-butyl group, octyl group, ethylhexyl group, cyclohexyl group, hydroxyethyl group , A benzyl group, etc.), N-aryl (meth) acrylamide (as the aryl group, for example, phenyl group, naphthyl group, hydroxyphenyl group, etc.), N, N-dialkyl (meth) acrylamide (as the alkyl group, for example, Methyl group, ethyl group, butyl group, isobutyl group, ethylhexyl group, cyclohexyl group, etc.), N, N-diaryl (meth) acrylamide (eg, aryl group such as phenyl group), N-methyl- N-phenyl (meth) acrylamide, N-hydroxyethyl N-methyl (meth) acrylamide and the like: vinyl esters such as vinyl acetate, vinyl butyrate, vinyl isobutylate, vinyl acetoacetate, vinyl benzoate and the like: styrenes such as styrene, methyl styrene, dimethyl styrene and ethyl styrene , Isopropyl styrene, butyl styrene, hexyl styrene, chloromethyl styrene, trifluoromethyl styrene, ethoxymethyl styrene, methoxy styrene, dimethoxy styrene, chloro styrene, dichloro styrene, bromo styrene, etc .: (meth) acrylonitrile, (meth) acrylic acid And polyvinyl methyl ether.

  These compounds may have one type of repeating unit or a copolymer composed of two or more types of repeating units. These compounds may have a melting point. In such a case, a compound having a melting point of 40 to 180 ° C. is particularly preferable. Examples of the compound having such a melting point include polyethylene oxide, polystyrene oxide, polycaprolactone and the like. Since this melting point varies depending on the weight average molecular weight, it cannot be generally stated. For example, polyethylene oxide has such a melting point when the weight average molecular weight is about 1000 or more.

  Among them, polyethylene oxide and polypropylene oxide monoethers (the monoethers include monomethyl ether, monoethyl ether, monooleyl ether, monolauryl ether, monostearyl ether, monononylphenyl ether, monooctylphenyl ether, monolanolin alcohol) Ethers and the like), monoesters of polyethylene oxide and polypropylene oxide (the monoesters include monoacetic acid esters, mono (meth) acrylic acid esters, monooleic acid esters, monolauric acid esters, monostearic acid esters, monoesters) Lanolin fatty acid esters and the like), polycaprolactone, and the like are preferable, and polyethylene oxide monoethers and monoesters are particularly preferable.

  The reaction ratio between the active hydrogen of (B) and the isocyanate group of (A) is preferably 1/100 to 50/100 mol ratio, particularly preferably 2/100 to 40/100. When the reaction ratio is less than 1/100, the effect of improving the sensitivity is insufficient, and when it exceeds 50/100, the amount of isocyanate groups decreases, so that capsule formation becomes difficult. The addition reaction between the active hydrogen of (B) and the isocyanate group of (A) is, for example, heating both compounds in an organic solvent not containing active hydrogen (about 50 to 100 ° C.) with stirring. Or by heating at a relatively low temperature (about 40 to 70 ° C.) while adding a catalyst such as stannous octylate or dibutyltin diacetate. Examples of the organic solvent include ethyl acetate, chloroform, tetrahydrofuran, methyl ethyl ketone, acetone, acetonitrile, toluene and the like. The adduct of compound (A) and compound (B) may be one type or a mixture of two or more types.

  In addition to the adduct of the compound (A) and the compound (B), a known polyfunctional isocyanate having two or more isocyanate groups can be used in combination as a raw material for the microcapsules. As an example of such a polyfunctional isocyanate, the compounds exemplified as the aforementioned compound (A) can be used in combination at an appropriate ratio.

  These polyfunctional isocyanate compounds may be used alone or in combination of two or more. However, in this case, the ratio of the polyfunctional isocyanate used in combination with the compound (B) of the present invention and the adduct of the compound (A) is preferably 100/0 to 10/90 mass ratio.

The isocyanate compound is a reaction product of a polyfunctional isocyanate (A) having two or more isocyanate groups and a polyether derivative (I) having a terminal amino group represented by the following general formula (I). Some are also preferred.

[Wherein, X represents —CO— or —SO ₂ —, A represents an arylene or alkylene group, L represents an alkylene group, and R represents an alkyl group, an aryl group or an acyl group. m represents 0 or 1, and n represents a number of 10 to 500 in terms of the average number of moles added of the polyether group. ]

  Here, the polyfunctional isocyanate (A) having two or more isocyanate groups is the same as described above.

Next, the polyether derivative (I) will be described.
In the general formula (I), X represents —CO— or —SO ₂ —, among which —CO— is preferable.
A in the general formula (I) represents arylene or alkylene.
The arylene represented by A may have a substituent, and is preferably arylene having 6 to 30 carbon atoms, particularly preferably arylene having 6 to 20 carbon atoms. When substituted, the substituent is preferably a halogen atom, an alkyl group, an alkoxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, or a cyano group, and particularly preferably a halogen atom, an alkyl group, or an alkoxy group. Specific examples of such arylene include phenylene, biphenylene, naphthalene, methylphenylene, methoxyphenylene, and the like.

  The alkylene represented by A may have a substituent or may have a branch, and is preferably an alkylene having 1 to 30 carbon atoms, particularly 1 to 20 carbon atoms in total. Alkylene is preferred. When substituted, the substituent is preferably an aryl group, an alkenyl group, an alkoxy group, or an alkoxycarbonyl group, and particularly preferably an aryl group. Specific examples of such alkylene include methylene, ethylene, propylene, tetramethylene, phenylmethylene and the like.

In the general formula (I), m represents 0 or 1, and 1 is preferable.
Specific examples of such a group represented by — (X) _m —A—NH ₂ include aminoethyl group, aminopropyl group, 4-aminobenzoyl group, 3-aminobenzoyl group, 4-amino group. Examples thereof include a benzenesulfonyl group, an aminoacetyl group, and an aminoethylsulfonyl group.

In general formula (I), L represents alkylene.
The alkylene represented by L may have a substituent or may have a branch, and is preferably an alkylene having 2 to 20 carbon atoms, particularly 2 to 10 carbon atoms. Alkylene is preferred. When substituted, the substituent is preferably an aryl group, an alkenyl group, an alkoxy group, or an acyl group, and more preferably an aryl group. Specific examples of such alkylene include ethylene, propylene, tetramethylene, phenylethylene, cyclohexylene, vinylethylene, phenoxymethylethylene and the like.

In the general formula (I), the repeating unit — (L—O) _n — may represent an independent group in n repetitions, but is preferably the same group. Specific examples of the polyether having such a repeating unit include polyethylene oxide, polypropylene oxide, polytetramethylene oxide, polystyrene oxide, polycyclohexylene oxide, polyethylene oxide-polypropylene oxide-block copolymer, polyethylene oxide-polypropylene oxide. A random copolymer etc. are mentioned.

In general formula (I), R represents an alkyl group, an aryl group, or an acyl group.
The alkyl group represented by R may have a substituent or may have a branch, and preferably has a total carbon number of 1 to 30, particularly 1 to 20 carbon atoms. Are preferred. In the case of substitution, the substituent is preferably an aryl group, an alkenyl group, or an alkoxy group. Specific examples of such an alkyl group include a methyl group, an ethyl group, a butyl group, an isopropyl group, a behenyl group, a benzyl group, an allyl group, an oleyl group, and a methoxyethyl group.

  The aryl group represented by R may have a substituent, preferably has a total carbon number of 6 to 30, and particularly preferably has a total carbon number of 6 to 20. When substituted, the substituent is preferably a halogen atom, an alkyl group, an alkenyl group, an alkynyl group or an alkoxy group, and particularly preferably an alkyl group or an alkoxy group. Specific examples of such an aryl group include a phenyl group, a nonylphenyl group, an octylphenyl group, a fluorophenyl group, a styrylphenyl group, a phenylethenylphenyl group, and a methoxyphenyl group.

The acyl group represented by R may be an aliphatic or aromatic acyl group, may have a substituent, may further have a branch, and has a total carbon number of 2 to 30. Those having a total carbon number of 2 to 20 are particularly preferable. When substituted, the substituent does not include an amino group and a nitro group, and is preferably an alkyl group, an aryl group, an alkenyl group, or an alkoxy group. Specific examples of such an acyl group include an acetyl group, a benzoyl group, a (meth) acryloyl group, an oleoyl group, a lauroyl group, a stearoyl group, and a methoxybenzoyl group.
As described above, among such groups represented by R, an alkyl group and an acyl group are preferable, and an alkyl group is particularly preferable.

  In the general formula (I), n represents an average addition mole number of the polyether group of 10 to 500, and the average addition mole number is preferably 10 to 400, and most preferably 10 to 300. .

  Specific examples of the polyether derivative having a terminal amino group represented by the general formula (I) of the present invention are shown below, but the present invention is not limited thereto.

(Method for producing polyether derivative of general formula (I))
Next, the manufacturing method of polyether derivative (I) is demonstrated.
The polyether derivative having a terminal amino group represented by the general formula (I) can be synthesized using a commercially available product or by a known method. Examples of the known synthesis method include J. Org. Org. Chem. <45>, 5364 (1980), JP-A-11-263834, Eur. Poly. J. et al. <19>, 341 (1983), J. Am. Am. Chem. Soc. <118>, 10150 (1996), Tetrahedron Letters <43>, 1529 (2002), etc. can be referred to.

  When m represents 1 in the general formula (I), a polyether derivative represented by the following general formula (II) is reacted with an aromatic nitro compound represented by the following general formula (III). To produce a polyether derivative (m = 1) of the general formula (I) by converting it to a nitro compound of the general formula (IV) shown below, followed by hydrogen reduction in the presence of a catalyst for catalytic hydrogen reduction. Can do.

  For the reaction between the polyether derivative and the aromatic nitro compound, it is preferable to use a base such as triethylamine, pyridine, DBU, or sodium hydride. A solvent may be used for the reaction, and toluene, acetonitrile, tetrahydrofuran, and methylene chloride are preferable as the solvent. The reaction temperature is preferably 0 ° C. to 100 ° C. or the reflux temperature of the solvent used.

  As the catalyst for catalytic hydrogen reduction used for the hydrogen reduction of the nitro compound of the general formula (IV), a known catalyst can be used. Regarding the catalyst, “4th edition experimental chemistry course 26”, pages 251 to 266. Page (Japanese Chemical Society, Maruzen, 1992). A solvent may also be used, and methanol, ethanol, 2-propanol, tetrahydrofuran, and chloroform are preferable as the solvent. The reaction temperature of the reaction is preferably 0 ° C. to 60 ° C. or the reflux temperature of the solvent used.

In the present invention, the reaction ratio between the polyether derivative having an amino group at the terminal represented by the general formula (I) and the polyfunctional isocyanate (A) having two or more isocyanate groups is 1/100 to 50. / 100 mol ratio is preferable, and 2/100 to 40/100 is particularly preferable. When the molar reaction ratio is less than 1/100, the effect of improving the sensitivity may be insufficient. When the molar reaction ratio exceeds 50/100, the remaining amount of isocyanate groups is too small to form capsules. May be difficult.
The addition reaction between the polyether derivative having an amino group at the terminal represented by the general formula (I) and at least the polyfunctional isocyanate (A) is performed, for example, in an organic solvent having no active hydrogen in both compounds, It can be obtained by stirring at room temperature or heating (about 20 to 80 ° C.). Examples of the organic solvent include ethyl acetate, chloroform, tetrahydrofuran, methyl ethyl ketone, acetone, acetonitrile, toluene and the like.
In addition, as an isocyanate compound used by this invention, the addition reaction product of the polyether derivative which has an amino group at the terminal represented by this general formula (I), and polyfunctional isocyanate (A) is single 1 type independently. Even if it uses, 2 or more types of mixtures may be used.

  As the isocyanate compound used in the present invention, a known polyfunctional isocyanate having two or more isocyanate groups can be used in combination in addition to the above as a raw material for microcapsules. As examples of such polyfunctional isocyanates, the compounds exemplified as the aforementioned difunctional isocyanate can be used in combination at an appropriate ratio.

  These polyfunctional isocyanate compounds may be used alone or in combination of two or more. However, when used in combination, the mass ratio of the polyfunctional isocyanate used in combination with the reaction product of the polyether derivative having an amino group at the terminal represented by the general formula (I) of the present invention and at least a bifunctional isocyanate is 100. The range of / 0 to 10/90 is preferable, and the range of 90/10 to 15/85 is more preferable.

[Other ingredients]
As other components necessary for producing the microcapsules, that is, substances encapsulated in the capsule, hydrophobic solvent, aqueous phase, and the like, those corresponding to the current state of the art can be used. Examples of substances that can be encapsulated in microcapsules are perfume oils, plant protection agents, reactive adhesives, pharmaceuticals, etc., but in the present invention, diazo compounds or electron donating dye precursors are included as coloring components. It is preferred to produce microcapsules that When the diazo compound or the electron donating dye precursor is used, it is preferably dissolved in a high boiling point solvent and encapsulated in microcapsules.

  The heat-sensitive recording material of the present invention has a basic structure in which a heat-sensitive recording layer containing the microcapsules is provided on a support. Furthermore, in the multicolor thermosensitive recording material of the present invention, a thermosensitive recording layer containing cyan, magenta and yellow microcapsules is provided on a (transparent) support, and at least one of these is a basic comprising the above microcapsules. It has a configuration. If desired, a black thermosensitive recording layer may be provided on the back surface of the transparent support.

(Coloring component and developer)
Examples of the electron donating dye precursor encapsulated in the microcapsule of the present invention include triarylmethane compounds, diphenylmethane compounds, thiazine compounds, xanthene compounds, spiropyran compounds, and the like. Compounds and xanthene compounds are useful because of their high color density.

  Specific examples thereof include 3,3-bis (p-dimethylaminophenyl) -6dimethylaminophthalide (that is, crystal violet lactone), 3,3-bis (p-dimethylamino) phthalide, 3- (p- Dimethylaminophenyl) -3- (1,3-dimethylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, 3- (o- Methyl-p-dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, 3- (o-methyl-p-diethylaminophenyl) -3- (1'-ethyl-2-methylindole-3) -Yl) phthalide, 4,4'-bis (dimethylamino) benzhydrin benzyl ether, N-halophenylleucooramine, N-2,4 -Trichlorophenyl leucooramine, rhodamine-B-anilinolactam, rhodamine (p-nitroanilino) lactam, rhodamine-B- (p-chloroanilino) lactam, 2-benzylamino-6-diethylaminofluorane, 2-anilino-6 -Diethylaminofluorane, 2-anilino-3-methyl-6-diethylaminofluorane, 2-anilino-3-methyl-6-cyclohexylmethylaminofluorane, 2-anilino-3-methyl-6-isoamylethylaminofluorane 2- (o-chloroanilino) -6-diethylaminofluorane, 2-octylamino-6-diethylaminofluorane, 2-ethoxyethylamino-3-chloro-2-diethylaminofluorane, 2-anilino-3-chloro- 6-diethylamino Luolan, benzoyl leucomethylene blue, p-nitrobenzyl leucomethylene blue, 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3,3'-dichloro-spiro-dinaphthopyran, 3-benzylpyrodinaftpyran, 3- And propyl-spiro-dibenzopyran.

  Examples of the electron-accepting compound (developer (not included in the microcapsule)) used in combination with the electron-donating dye precursor include phenol derivatives, salicylic acid derivatives, and hydroxybenzoic acid esters. Among these, bisphenols and hydroxybenzoic acid esters are particularly preferable. For example, 2,2-bis (p-hydroxyphenyl) propane (bisphenol A), 2,2-bis (p-hydroxyphenyl) pentane, 2,2-bis (p-hydroxyphenyl) ethane, 2,2-bis (P-hydroxyphenyl) butane, 2,2-bis (4'-hydroxy-3 ', 5'-dichlorophenyl) propane, 1,1- (p-hydroxyphenyl) cyclohexane, 1,1- (p-hydroxyphenyl) ) Propane, 1,1- (p-hydroxyphenyl) pentane, 1,1- (p-hydroxyphenyl) -2-ethylhexane, 3,5-di (α-methylbenzyl) salicylic acid and its polyvalent metal salt, 3,5-di (tert-butyl) salicylic acid and its polyvalent metal salt, 3-α, α-dimethylbenzylsalicylic acid and its polyvalent metal salt, p-hy Proxy-butylbenzoic acid, p- hydroxybenzoic acid benzyl, p- hydroxybenzoate, 2-ethylhexyl can be mentioned p- phenylphenol and p- cumylphenol. In the present invention, two or more of these electron-accepting compounds can be used in combination at any ratio.

  It is preferable to add a sensitizer for promoting the reaction to the heat-sensitive recording layer. As the sensitizer, a low-melting-point organic compound having moderately aromatic groups and polar groups in the molecule is preferable. Specific examples thereof include p-benzyloxybenzoic acid benzyl, α-naphthylbenzyl ether, β-naphthylbenzyl ether, β-naphthoic acid phenyl ester, α-hydroxy-β-naphthoic acid phenyl ester, β-naphthol- (p -Chlorobenzyl) ether, 1,4-butanediol phenyl ether, 1,4-butanediol-p-methylphenyl ether, 1,4-butanediol-p-ethylphenyl ether, 1,4-butanediol-m- Methyl phenyl ether, 1-phenoxy-2- (p-tolyloxy) ethane, 1-phenoxy-2- (p-ethylphenoxy) ethane, 1-phenoxy-2- (p-chlorophenoxy) ethane, p-benzylbiphenyl, p-toluenesulfonamide, 4- (2-ethylhexylo) ) Phenyl sulfonamide, include 4-n-pentyloxyphenyl sulfonamide. In the present invention, these sensitizers can be used in combination of two or more at any ratio.

As the diazonium salt compound encapsulated in the microcapsule of the present invention, known compounds can be used. Examples of the known diazonium salt compound include compounds represented by the following general formula.
Ar-N ₂ ⁺ · X ⁻
[In the above formula, Ar represents an aryl group, and X ⁻ represents an acid anion. ]

  The diazonium salt compound reacts with a phenol compound or a compound having active methylene to form a so-called dye, and further decomposes by irradiation with light (generally ultraviolet rays) and denitrifies to lose its reaction activity. It is. Specific examples of the diazonium salt include 2,5-dibutoxy-4-morpholinobenzenediazonium, 2,5-octoxy-4-morpholinobenzenediazonium, 2,5-dibutoxy-4- (N- (2-ethylhexanoyl). ) Piperazino) benzenediazonium, 2,5-diethoxy-4- (N- (2- (2,4-di-tert-amylphenoxy) butyryl) piperazino) benzenediazonium, 2,5-dibutoxy-4-tolylthiobenzene Diazonium, 2,5-dibutoxy-4-chlorobenzenethiodiazonium, 2,5-diheptyloxy-4-chlorobenzenethiodiazonium, 3- (2-octyloxyethoxy) -4-morpholinobenzenediazonium, 4- N, N-dihexylamino-2-hexyloxybenzenediazo 4- (N-hexyl-N- (1-methyl-2- (p-methoxyphenoxy) ethyl) amino) -2-hexyloxybenzenediazonium and 4-N-hexyl-N-tolylamino-2-hexyloxy Examples thereof include benzenediazonium salts.

  The acid anions of the diazonium salt compounds include hexafluorophosphate salts, tetrafluoroborate salts, 1,5-naphthalene sulfonate salts, perfluoroalkyl carbonate salts, perfluoroalkyl sulfonate salts, zinc chloride salts, and chloride salts. A tin salt or the like can be used. Preferably, hexafluorophosphate salt, tetrafluoroborate salt, and 1,5-naphthalene sulfonate salt are preferable because they have low water solubility and are soluble in organic solvents. In the present invention, two or more different diazonium salt compounds can be mixed and used at an arbitrary ratio.

In a heat-sensitive recording layer using microcapsules enclosing a diazonium salt compound, a known heat sensitizer such as an arylsulfonamide compound may be added. Specific examples include toluenesulfonamide and ethylbenzenesulfonamide. In the present invention, two or more different heat sensitizers can be mixed and used.

  A coupler that forms a dye by reacting with a diazonium salt compound is used after being finely divided by emulsifying dispersion and / or solid dispersion. Specific examples of couplers include resorcin, flurucurine, sodium 2,3-dihydroxynaphthalene-6-sulfonate, 1-hydroxy-2-naphthoic acid morpholinopropylamide, 1,5-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2 , 3-dihydroxy-6-sulfanylnaphthalene, 2-hydroxy-3-naphthoic acid anilide, 2-hydroxy-3-naphthoic acid ethanolamide, 2-hydroxy-3-naphthoic acid octylamide, 2-hydroxy-3-naphthoic acid -N-dodecyloxypurpyramide, 2-hydroxy-3-naphthoic acid tetradecylamide, acetanilide, acetoacetanilide, benzoylacetanilide, 2-chloro-5-octylacetoacetanilide, 2,5-di-n-heptylo Siacetanilide, 1-phenyl-3-methyl-5-pyrazolone, 1- (2′-octylphenyl) -3-methyl-5-pyrazolone, 1- (2 ′, 4 ′, 6′-trichlorophenyl) -3 -Benzamido-5-pyrazolone, 1- (2 ', 4', 6'-trichlorophenyl) -3-anilino-5-pyrazolone, 1-phenyl-3-phenylacetamido-5-pyrazolone, 1- (2-dodecyl) Oxyphenyl) -2-methyl carbonate cyclohexane-3,5-dione, 1- (2-dodecyloxyphenyl) cyclohexane-3,5-dione, N-phenyl-N-dodecylbarbituric acid, N-phenyl-N- (2,5-Dioctyloxyphenyl) barbituric acid and N-phenyl-N- (3-stearyloxy) butylbarbituric acid It can be mentioned. Two or more of these couplers can be used in combination to obtain the desired color hue.

Furthermore, in order to promote the dye-forming reaction, it is common to add a basic compound which is finely divided by emulsification dispersion and / or solid dispersion. Examples of the basic substance include inorganic or organic basic compounds and compounds that release an alkaline substance by decomposition or the like when heated. Typical examples include organic ammonium salts, organic amines, amides, ureas and thioureas and their derivatives, thiazoles, pyrroles, pyrimidines, piperazines, guanidines, indoles, imidazoles, imidazolines, triazoles. , Morpholines, piperidines, amidines, formazines, pyridines and the like nitrogen-containing compounds.
Specific examples thereof include tricyclohexylamine, tribenzylamine, octadecylbenzylamine, stearylamine, allylurea, thiourea, methylthiourea, allylthiourea, ethylenethiourea, 2-benzylimidazole, 4-phenylimidazole, 2-phenyl- 4-methylimidazole, 2-undecylimidazoline, 2,4,5-trifuryl-2-imidazoline, 1,2-diphenyl-4,4-dimethyl-2-imidazoline, 2-phenyl-2-imidazoline, 1,2 , 3-triphenylguanidine, 1,2-dicyclohexylguanidine, 1,2,3-tricyclohexylguanidine, guanidine trichloroacetate, N, N′-dibenzylpiperazine, 4,4′-dithiomorpholine, morpholinium trichloro Acetate, - it can be exemplified aminobenzothiazole and 2-benzoyl-hydrazino-benzothiazole. Two or more of these may be used in combination.

[Microcapsule formation and thermal recording material]
The microcapsule of the present invention can be produced, for example, as follows. As the hydrophobic solvent for forming the core of the microcapsule, an organic solvent having a boiling point of 100 to 300 ° C. is preferable. Specifically, alkyl naphthalene, alkyl diphenyl ethane, alkyl diphenyl methane, diphenyl ethane alkyl adduct, alkyl biphenyl, chlorinated paraffin, tricresyl phosphate and other maleic acid derivatives, maleic acid-di-2-ethylhexyl maleic Examples include acid esters and adipic acid esters. You may use these in mixture of 2 or more types. When the solubility of the diazonium salt compound or the electron donating dye precursor in these hydrophobic solvents is not sufficient, a low boiling point solvent can be used in combination. As the low-boiling organic solvent used in combination, an organic solvent having a boiling point of 40 to 100 ° C. is preferable, and specific examples include ethyl acetate, butyl acetate, methylene chloride, tetrahydrofuran and acetone. Moreover, you may mix and use these 2 or more types. When only a solvent having a low boiling point (a boiling point of about 100 ° C. or less) is used for the capsule core, the solvent evaporates, and a so-called coreless capsule in which only the capsule wall and the diazonium salt compound or the electron donating dye precursor exist is present. Easy to form.

Depending on the type of diazonium salt, it may move to the aqueous phase side during the microencapsulation reaction, and in order to suppress this, an acid anion may be appropriately added to the water-soluble polymer solution in advance. Such acid anions include PF ₆ ⁻ , B (—Ph) ₄ ⁻ (where Ph is a phenyl group), ZnCl ₂ ⁻ , C _n H _{2n + 1} COO ⁻ (where n is an integer of 1 to 9) and C _p F _{2p + 1} SO ₃ ⁻ (wherein p is an integer of 1 to 9). Various additives may be used in combination for storage stability, color development sensitivity adjustment, and the like.

In the present invention, at the time of microencapsulation, the compound having active hydrogen used for polymerization of an isocyanate compound for forming a microcapsule wall is only water. Therefore, in the method of the present invention in which a liquid containing a core substance, a microcapsule wall precursor, and a hydrophobic organic solvent is added to an aqueous phase and emulsified and reacted to form a microcapsule wall, the aqueous phase is water alone or Only water and a water-soluble protective colloid having a weight average molecular weight of 2000 or less or / and a surfactant having a weight average molecular weight of 2000 or less.
Here, the surfactant having a weight average molecular weight of 2000 or less is not particularly limited, and examples thereof include an anionic surfactant, a nonionic surfactant, and a cationic surfactant.
The anionic surfactant used in the present invention will be described in detail.
The type of anionic surfactant is not particularly limited, but alkyl sulfate, alkyl benzene sulfonate, alkyl naphthalene sulfonate, polyoxyethylene alkyl ether sulfate, alkyl diphenyl disulfonate, and dialkyl) sulfosuccinate Preferable examples include acid salts. The cation forming the salt is preferably a monovalent alkali metal ion or ammonium ion, and more preferably a monovalent alkali metal ion. Preferred examples of the monovalent alkali metal ion include sodium ion and potassium ion. Specific examples of the anionic surfactant include sodium dodecylbenzenesulfonate, sodium lauryl sulfate, polyoxyethylene sodium lauryl ether sulfate, sodium butylnaphthalenesulfonate, and di (2-ethylhexylsulfosuccinate sodium). These are particularly preferable, and these may be used alone or in combination of two or more.

  In the present invention, compounds such as aromatic sulfonate formalin condensates and aromatic carboxylate formalin condensates can also be used as surfactants (emulsification aids). Specific examples include compounds represented by the following general formula (A).

[In General Formula (A), R represents an alkyl group having 1 to 4 carbon atoms, X represents —SO ₃ ^— or —COO ^— , and M represents a sodium atom or a potassium atom. q represents an integer of 1 to 20]
This surfactant has a structure in which an aromatic sulfonic acid or an aromatic carboxylic acid, for example, benzenesulfonic acid, benzoic acid, naphthalenesulfonic acid, naphthalenecarboxylic acid, and derivatives thereof are condensed with formalin. The average degree of polymerization is preferably 2 to 10. The aromatic ring is more preferably one to which an alkyl group having 1 to 4 carbon atoms or a substituted alkyl group is added. A plurality of these surfactants may be mixed and used.

  Alkyl glucoside compounds can also be used in the same manner. Specifically, it is a compound represented by the following general formula (B).

[In General Formula (B), R represents an alkyl group having 4 to 18 carbon atoms. q represents an integer of 0-2. ]
In the present invention, any surfactant may be used alone, or two or more kinds may be used in combination as appropriate.

In the present invention, the surfactant may be added to either the oil phase or the aqueous phase, but it is easier to add to the aqueous phase because of its low solubility in organic solvents. 0-50 mass% is preferable with respect to the mass in an aqueous phase, 0.001-20 mass% is more preferable, and 1-10 mass% is especially preferable.
Water-soluble protective colloids include polyvinyl alcohol and its modified products, polyacrylic acid amide and its derivatives, ethylene-vinyl acetate copolymer, styrene-maleic anhydride copolymer, ethylene-maleic anhydride copolymer, Examples include isobutylene-maleic anhydride copolymer, polyvinylpyrrolidone, ethylene-acrylic acid copolymer, vinyl acetate-acrylic acid copolymer, carboxymethylcellulose, methylcellulose, casein, gelatin, starch derivative, arabic gum, sodium alginate and the like.
In the present invention, the water-soluble protective colloid preferably has a weight average molecular weight of 2000 or less and has no or low reactivity with an isocyanate compound. For example, those having a reactive amino group in the molecular chain in advance It is necessary to eliminate the reactivity.
0-50 mass% is preferable, as for content of the water-soluble protective colloid in an aqueous phase, 0.001-20 mass% is more preferable, and 1-10 mass% is especially preferable.

  An oil phase composed of the core substance or the like is added to the aqueous phase. At that time, the aqueous solution is emulsified and dispersed by adding it while stirring with a high shear stirring device such as a homogenizer. After emulsification, a polymerization reaction catalyst for an isocyanate compound is added, or the temperature of the emulsion is increased to perform a capsule wall forming reaction.

  A coupling reaction quencher can be added as appropriate to the microcapsule solution encapsulating the prepared diazonium salt. Examples of the reaction quencher include hydroquinone, sodium bisulfite, potassium nitrite, hypophosphorous acid, stannous chloride and formalin. These compounds are described in JP-A-60-214992. In general, during the encapsulation process, diazonium salt compounds often elute in the aqueous phase. As a method for removing this, filtration, ion exchange, electrophoresis, chromatography, gel filtration, reverse Methods such as osmosis treatment, ultrafiltration treatment, dialysis treatment, and activated carbon treatment can be used. Among these, ion exchange treatment, reverse osmosis treatment, ultrafiltration treatment and dialysis treatment are preferred, and treatment with a cation exchanger and treatment with a combination of a cation exchanger and an anion exchanger are particularly preferred. These methods are described in JP-A-61-219688.

  In the present invention, an electron accepting compound, a thermal sensitizer, a coupler, a basic compound, and the like can be added to the thermosensitive coloring layer. These can be mixed as appropriate and added separately after being emulsified and dispersed, or solid dispersed and atomized, or mixed as appropriate, and then added after being emulsified and dispersed, solid dispersed and atomized. In the emulsifying and dispersing method, these compounds are dissolved in an organic solvent, and a water-soluble polymer aqueous solution is added while stirring with a homogenizer or the like. In promoting the formation of fine particles, it is preferable to use the aforementioned hydrophobic organic solvent, surfactant, and water-soluble polymer.

  To solidly disperse couplers and basic substances, electron accepting compounds, thermal sensitizers, etc., these powders are put into a water-soluble polymer aqueous solution, and finely divided using a known dispersing means such as a ball mill. can do. The microparticulation is preferably carried out so as to obtain a particle diameter satisfying the characteristics required for the multicolor thermosensitive recording material such as thermal sensitivity, storage stability, transparency of the recording layer and production suitability, and the production method thereof.

  The microcapsule solution and the preparation solution of the thermal sensitizer, electron accepting compound, coupler, basic compound and the like are mixed at an appropriate ratio and coated on a support. In general, 1 to 10 moles, preferably 2 to 6 moles of the coupler is appropriate for 1 mole of the diazonium salt compound. The optimum addition amount of the basic compound varies depending on the basic strength, but is generally 0.5 to 5 mol of the diazonium salt compound. The electron-accepting compound (developer) is generally added in the range of 0.5 to 30 mol, preferably in the range of 1 to 20 mol, per 1 mol of the electron-donating dye precursor. More preferably, it is added within the range of 3 to 15 mol. The thermal sensitizer is generally added within a range of 0.1 to 20 mol with respect to the electron donating dye precursor, but is preferably added within a range of 0.5 to 10 mol.

  As the support on which these coating solutions are applied, known materials can be used as the support for the heat-sensitive recording material. Examples thereof include paper, coated paper obtained by applying clay or the like on paper, laminated paper obtained by laminating polyethylene, polyester or the like on paper, synthetic paper, plastic film such as polyethylene terephthalate, polyimide, or triacetyl cellulose. Examples of the transparent support include the polyethylene terephthalate, triacetyl cellulose, and plastic films such as polystyrene, polypropylene, and polyethylene.

  In the present invention, a protective layer may be provided on the thermosensitive coloring layer in order to further improve the light fastness and the like. In a multicolor thermosensitive material, an intermediate layer may be provided between the thermosensitive recording layers in order to further improve color reproducibility. As a material for the layer used in these, an emulsion (latex) of a water-soluble polymer compound or a hydrophobic polymer compound is preferable.

  A multicolor thermal recording material and a recording method thereof will be described. First, the outermost heat-sensitive layer containing the diazonium compound (first heat-sensitive recording layer, usually yellow color-developing layer) is developed by low-energy thermal recording, and then the absorption wavelength range of the diazonium compound contained in the heat-sensitive layer The entire surface is irradiated with a light source that emits the light to photodecompose the diazonium compound remaining in the uppermost heat-sensitive layer.

  Next, a second heat-sensitive layer (second heat-sensitive recording) containing a diazonium compound having a higher energy than the previous light and having a light absorption wavelength range different from that of the absorption wavelength range of the diazonium compound contained in the first layer. Layer, usually a magenta coloring layer), and then irradiating the entire surface again with a light source that emits light in the absorption wavelength range of the diazonium compound, whereby the diazonium compound remaining in the second heating layer Is photolyzed. Finally, the layer (third layer) containing the electron donating dye precursor of the innermost layer (third heat-sensitive recording layer, usually cyan coloring layer) is developed with higher energy to complete image recording.

  In the above case, it is preferable that the outermost layer and the second layer are transparent heat-sensitive layers because each color is brilliant. In the present invention, a multicolor image can also be obtained by using a transparent support as the support and applying any one of the three layers to the back of the transparent support. In this case, the uppermost heat-sensitive layer on the side opposite to the image viewing side does not need to be transparent.

  As a light source used for photolysis of the diazonium compound, an ultraviolet lamp is usually used. An ultraviolet lamp is a fluorescent tube in which mercury vapor is filled in a tube, and fluorescent tubes having various emission wavelengths can be obtained depending on the type of phosphor applied to the inner wall of the tube.

  In the multicolor thermosensitive recording material, the third thermosensitive recording layer can be formed by combining an appropriate diazonium salt compound and a coupler compound.

  The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to these examples. In the present embodiment, “parts” and “%” all represent “parts by mass” and “mass%”.

[Synthesis Example 1] 75 parts of polyethylene glycol monomethyl ether (weight average molecular weight: 5000) is dissolved in 125 parts of dry chloroform, and 7.5 parts of molecular sieve 4A are added. Drying is performed for 3 hours under a dry nitrogen gas stream. 100 parts of a polyisocyanate compound (xylylene diisocyanate / trimethylolpropane adduct (Takenate D110N, 75% ethyl acetate solution, manufactured by Takeda Pharmaceutical Co., Ltd.)) is added thereto. (Manufactured by Yoshitomi Pharmaceutical Co., Ltd.) 160 mg was added for 1 hour at room temperature and then for 3 hours at 50 ° C. Thus, a solution (50%) of the isocyanate compound (1) was obtained.

[Synthesis Example 2] The isocyanate compound (2) was synthesized in the same manner as in Synthesis Example 1 except that the polyethylene glycol monomethyl ether (weight average molecular weight: 5000) in Synthesis Example 1 was changed to polyethylene glycol monomethyl ether (weight average molecular weight: 2000). A solution (50%) was obtained.

[Synthesis Example 3] Polyethylene glycol monomethyl ether (weight average molecular weight: 5000) of Synthesis Example 1 is changed to polyethylene glycol monomethyl ether (Niox M-4000, weight average molecular weight: 4000), and dry chloroform is changed to dry acetonitrile. A solution (50%) of the isocyanate compound (3) was obtained in the same manner as in Synthesis Example 1 except for changing.

[Synthesis Example 4] 75 parts of polyethylene glycol monomethyl ether of Synthesis Example 3 (manufactured by NOF Corporation, UNIOX M-4000, weight average molecular weight: 4000) to 70 parts, 125 parts of dry acetonitrile to 70 parts, xylylene diisocyanate / Trimethylolpropane adduct (Takenate D110N, 75% ethyl acetate solution, Takeda Pharmaceutical Co., Ltd.) 100 parts in the same manner as in Synthesis Example 3 except that 100 parts were changed to 80 parts respectively (50 %).

Synthesis Example 5 Isocyanate Compound (5) in the same manner as in Synthesis Example 2, except that 75 parts of polyethylene glycol monomethyl ether (weight average molecular weight: 2000) in Synthesis Example 2 is changed to 30 parts and 125 parts of dry chloroform are changed to 80 parts. Solution (50%) was obtained.

[Synthesis Example 6] Synthesis Example 1 except that polyethylene glycol monomethyl ether (weight average molecular weight: 5000) in Synthesis Example 1 is changed to polyethylene glycol monononyl phenyl ether (weight average molecular weight: 3000), and dry chloroform is changed to dry acetonitrile. Similarly, a solution (50%) of the isocyanate compound (6) was obtained.

[Synthesis Example 7] Synthesis Example 1 except that polyethylene glycol monomethyl ether (weight average molecular weight: 5000) of Synthesis Example 1 is changed to polyethylene glycol monostearate (weight average molecular weight: 3000), and dry chloroform is changed to dry acetonitrile. Similarly, a solution (50%) of the isocyanate compound (7) was obtained.

[Synthesis Example 8] 2.5 parts of n-butyl alcohol and 100 parts of a polyvalent isocyanate compound (xylylene diisocyanate / trimethylolpropane adduct (Takenate D110N, 75% ethyl acetate solution, Takeda Pharmaceutical Co., Ltd.)) Dissolve in 52.5 parts of ethyl 80 mg of stannous octylate (STANOCT, manufactured by Yoshitomi Pharmaceutical Co., Ltd.) is added in a water bath, and the mixture is stirred at room temperature for 1 hour and then at 50 ° C. for 3 hours. In this way, a solution (50%) of the isocyanate compound (8) was obtained.

[Synthesis Example 9]: Synthesis of Isocyanate Compound (9) An isocyanate compound (9) was synthesized according to the synthesis procedure shown below.
After 75 parts of the compound of the specific compound example (1-2) was dried using an vacuum pump at an external temperature of 80 ° C. for 2 hours, the temperature was returned to room temperature. 100 parts of a polyvalent isocyanate compound (xylylene diisocyanate / trimethylolpropane adduct (“Takenate D110N”, 75% ethyl acetate solution manufactured by Mitsui Takeda Chemical Co., Ltd.)) was added, and the mixture was stirred at 50 ° C. for 3 hours. In this way, a 50% solution of the isocyanate compound (9) was obtained.

[Synthesis Example 10]: Synthesis of Isocyanate Compound (10) Except that the compound of Specific Compound Example (1-2) used in Synthesis Example 9 was changed to the compound of Specific Compound Example (1-3) above. Obtained a 50% solution of the isocyanate compound (10) in the same manner as in Synthesis Example 9.

[Synthesis Example 11]: Synthesis of Isocyanate Compound (11) Except that the compound of the specific compound example (1-2) used in Synthesis Example 9 was changed to the compound of the specific compound example (1-1) described above. Obtained a 50% solution of the isocyanate compound (11) in the same manner as in Synthesis Example 9.

[Synthesis Example 12]: Synthesis of Isocyanate Compound (12) Except that the compound of Specific Compound Example (1-2) used in Synthesis Example 9 was changed to the compound of Specific Compound Example (3-1) above. Obtained a 50% solution of the isocyanate compound (12) in the same manner as in Synthesis Example 9.

Example 1
As a diazonium salt compound, 4.4 parts of the following compound A having a maximum absorption wavelength of decomposition at 420 nm is dissolved in 16.4 parts of ethyl acetate, and 7.3 parts of isopropyl biphenyl which is a high boiling point solvent is added to 2.5 parts of dibutyl phthalate. Was added and heated to mix uniformly.

  30% ethyl acetate of xylylene diisocyanate / trimethylolpropane adduct (Takenate D110N, 75% ethyl acetate solution, manufactured by Mitsui Takeda Chemical Co., Ltd.) and xylylene diisocyanate / bisphenol A adduct as capsule wall agent in the above mixture 4.5 parts of the isocyanate compound (1) described in Synthesis Example 1 was added to 4.3 parts of a mixture of 4.5 parts of the solution and stirred uniformly. Separately, 77 parts of ion-exchanged water to which 0.36 part of Scraph AG-8 (manufactured by Nippon Seika Co., Ltd.) was added was added, and the mixture (solution) of the diazonium salt compound was added, and emulsified with a homogenizer. Distributed. After adding 20 parts of water to the obtained emulsion and homogenizing it, an encapsulation reaction was performed for 3 hours while stirring at 40 ° C. Thereafter, the liquid temperature was lowered to 35 ° C., 6.5 parts of ion exchange resin Amberlite IRA68 (manufactured by Organo) and 13 parts of Amberlite IRC50 (manufactured by Organo) were added and further stirred for 1 hour. Thereafter, the ion exchange resin was filtered, and 0.4 part of 1% hydroquinone aqueous solution was added to 10 parts of the capsule liquid and stirred. In this way, a capsule solution of a diazonium salt compound was obtained. The average particle size of the capsules was 0.8 μm with LA700 (Horiba, Ltd. particle size measuring instrument).

Examples 2-12
A capsule solution was obtained in the same manner as in Example 1 except that the compounds of Synthesis Examples (2) to (12) were used in place of the isocyanate compound (1) described in Synthesis Example 1 used in Example 1.

Example A
As a diazonium chloride compound, 4.8 parts of the above compound A having a maximum absorption wavelength of decomposition at 420 nm is dissolved in 18.0 parts of ethyl acetate, and 5.35 parts of isopropyl biphenyl and 5.35 parts of diphenyl terephthalate, which are high boiling point solvents, are dissolved. Added and heated to mix evenly.

  To the above mixture, 9.5 parts of the isocyanate compound (4) (50% solution) described in Synthesis Example 4 was added as a capsule wall agent and stirred uniformly. Separately, a solution in which 0.38 parts of Scraph AG-8 (manufactured by Nippon Seika Co., Ltd.) was added to 83.2 parts of ion-exchanged water was prepared, and a mixed solution (solution) of the diazonium salt compound was added to the homogenizer. And emulsified and dispersed. After adding 20 parts of water to the obtained emulsion and homogenizing it, an encapsulation reaction was performed for 3 hours while stirring at 40 ° C. Thereafter, the liquid temperature was lowered to 35 ° C., 6.5 parts of ion exchange resin Amberlite IRA68 (manufactured by Organo) and 13 parts of Amberlite IRC50 (manufactured by Organo) were added, and the mixture was further stirred for 1 hour. Thereafter, the ion exchange resin was filtered, and 0.4 part of 1% hydroquinone aqueous solution was added to 10 parts of the capsule liquid and stirred. In this way, a capsule solution of a diazonium salt compound was obtained. The average particle size of the capsules was 0.87 μm using LA700 (Horiba particle size measuring instrument).

Example B-1
As a diazonium salt compound, 2.8 parts of the following compound B having a maximum absorption wavelength of decomposition at 365 nm is dissolved in 15.0 parts of ethyl acetate, and trimethylolpropane triacrylate (trade name: Light Ester TMP) 4 which is a high-boiling solvent. .16 parts, 7.76 parts of diphenyl phthalate and 0.08 parts of calcium dodecylbenzenesulfonate (Takemoto Yushi Co., Ltd. trade name (Pionin A-41-C), 70% methanol solution) are added and heated. And evenly mixed.

  To the above mixture, 12.74 parts of the isocyanate compound (4) (50% solution) described in Synthesis Example 4 was added as a capsule wall agent and stirred uniformly. 76 parts of ion-exchanged water was prepared, a mixed solution (solution) of the diazonium salt compound was added, and the mixture was emulsified and dispersed with a homogenizer. After adding 30 parts of water to the obtained emulsion and homogenizing it, an encapsulation reaction was carried out for 3 hours while stirring at 40 ° C. Thereafter, the liquid temperature was lowered to 35 ° C., 6.5 parts of ion exchange resin Amberlite IRA68 (manufactured by Organo) and 13 parts of Amberlite IRC50 (manufactured by Organo) were added, and the mixture was further stirred for 1 hour. Thereafter, the ion exchange resin was filtered. In this way, a capsule solution of a diazonium salt compound was obtained. The average particle size of the capsules was 0.6 μm using LA700 (Horiba particle size measuring instrument).

Example B-2
As a diazonium salt compound, 2.8 parts of the above compound B having a maximum absorption wavelength of decomposition at 365 nm is dissolved in 15.0 parts of ethyl acetate, and trimethylolpropane triacrylate (trade name: Light Ester TMP) 4 which is a high-boiling solvent. .16 parts, 7.76 parts of diphenyl phthalate and 0.08 parts of calcium dodecylbenzenesulfonate (Takemoto Yushi Co., Ltd. trade name (Pionin A-41-C), 70% methanol solution) are added and heated. And evenly mixed.

  Xylylene diisocyanate / trimethylolpropane adduct (Takenate D110N, 75% ethyl acetate solution, manufactured by Mitsui Takeda Chemical Co., Ltd.) 5.95 parts as a capsule wall agent in the above mixture, the isocyanate compound (4 ) (50% solution) 3.82 parts was added and stirred uniformly. 76 parts of ion-exchanged water was prepared, a mixed solution (solution) of the diazonium salt compound was added, and the mixture was emulsified and dispersed with a homogenizer. After adding 30 parts of water to the obtained emulsion and homogenizing it, an encapsulation reaction was carried out for 3 hours while stirring at 40 ° C. Thereafter, the liquid temperature was lowered to 35 ° C., 6.5 parts of ion exchange resin Amberlite IRA68 (manufactured by Organo) and 13 parts of Amberlite IRC50 (manufactured by Organo) were added, and the mixture was further stirred for 1 hour. Thereafter, the ion exchange resin was filtered. In this way, a capsule solution of a diazonium salt compound was obtained. The average particle size of the capsules was 0.65 μm with LA700 (Horiba, Ltd., particle size measuring instrument).

Example C-1
The following electron-donating dye precursor (H) 6.83 parts and diisopropylnaphthalene (Kureha Chemical Industry Co., Ltd. Cleavage: trade name KMC113) 5.36 parts were dissolved in 10.0 parts of ethyl acetate and mixed uniformly. .
10.0 parts of xylylene diisocyanate / trimethylolpropane adduct (Takenate D110N, 75% ethyl acetate solution, manufactured by Mitsui Takeda Chemical Co., Ltd.) as a capsule wall agent in the above mixture, the isocyanate compound (4 ) (50% solution) 6.43 parts was added and stirred uniformly. Separately, a solution prepared by adding 1.94 parts of a 10% Na dodecylbenzenesulfonate solution to 71 parts of ion-exchanged water was prepared, a mixed solution (solution) of the electron donating dye precursor was added, and the mixture was emulsified and dispersed with a homogenizer. After adding 40 parts of water to the obtained emulsified liquid and homogenizing it, an encapsulation reaction was performed for 3 hours while stirring at 65 ° C. Thus, a capsule liquid of the electron donating dye precursor was obtained. The average particle size of the capsules was 0.95 μm using LA700 (Horiba particle size measuring instrument).

Comparative Examples 1 and 2
Instead of preparing 77 parts of ion-exchanged water to which 0.36 part of Scraph AG-8 (manufactured by Nippon Seika Co., Ltd.) was added in Example 1, Scratch AG-8 (manufactured by Nippon Seika Co., Ltd.) 0 Microcapsules were prepared in the same manner as in Examples 1 and 2 except that 77 parts of a 6% phthalated gelatin (weight average molecular weight of about 83,000) aqueous solution to which 36 parts were added were prepared and used.

Comparative Example A
Instead of preparing a solution in which 0.38 part of Scraph AG-8 (manufactured by Nippon Seika Co., Ltd.) was added to 83.2 parts of ion-exchanged water in Example A, Scraph AG-8 (Nippon Seika Co., Ltd.) was prepared. A microcapsule was prepared in the same manner as in Example A except that 0.38 part was added to 83.2 parts of a 6% aqueous solution of phthalated gelatin (weight average molecular weight of about 83000) and 83.2 parts.

Comparative Example B-1
Instead of preparing 76 parts of ion-exchanged water in Example IV-1, a solution in which 21 parts of ion-exchanged water was added to 55 parts of 8% phthalated gelatin (weight average molecular weight of about 83,000) was prepared and used. Microcapsules were produced in the same manner as B-1.

Comparative Example C
In Example C, instead of preparing a solution prepared by adding 1.94 parts of Na dodecylbenzene sulfonate 10% solution to 71 parts of ion-exchanged water, 1.94 parts of Na dodecyl benzene sulfonate 10% solution, 8% PVA (weight average A microcapsule was prepared in the same manner as in Example C except that a solution in which 50 parts of a molecular weight of about 74800) (trade name: PVA217C, manufactured by Kuraray Co., Ltd.) and 21 parts of ion-exchanged water were prepared and used.

Comparative Example 2
Instead of preparing 77 parts of ion-exchanged water to which 0.36 part of Scraph AG-8 (50% by mass Nippon Seika Co., Ltd.) was added in Example 1, 0.2% phthalated gelatin (weight average molecular weight) About 83000) 77 parts of an aqueous solution were prepared, and microcapsules were prepared in the same manner as in Example 1 except that they were used.

Evaluation The capsules obtained in the above Examples and Comparative Examples were evaluated for particle size when left for 1 day and 3 days in an unstirred dissolved state at 42 ° C. immediately after encapsulation.
The results are shown in Table 1.

  From Table 1, it can be seen that according to the method of the present invention, the capsules are stable without aggregation.

  According to the present invention, it is possible to obtain a capsule in which the microcapsule has little variation in particle size with time. Therefore, if this is used for a heat-sensitive recording material, a heat-sensitive recording material in which changes in heat sensitivity are suppressed can be obtained.

Claims (15)

Next ingredients (1) and (2)
(1) an oil phase component containing at least an oil-soluble core substance enclosed in a microcapsule, a microcapsule wall precursor, and a hydrophobic organic solvent;
(2) Water or a water phase component comprising water and a water-soluble protective colloid having a weight average molecular weight of 2000 or less and / or a surfactant having a weight average molecular weight of 2000 or less,
A method for producing a microcapsule comprising emulsifying a liquid composed of the above and forming a microcapsule wall by interfacial polymerization reaction.   The method for producing microcapsules according to claim 1, wherein the concentration of the protective colloid in the aqueous phase is 0 to 50% by mass of the total aqueous phase components.   The method for producing microcapsules according to claim 1 or 2, wherein the concentration of the surfactant in the aqueous phase is 0 to 50% by mass of the total aqueous phase component.   The method for producing microcapsules according to claim 1, 2 or 3, wherein the microcapsule wall precursor is an isocyanate compound.   At least one of the isocyanate compounds is a polyfunctional isocyanate (A) having two or more isocyanate groups, and a compound (B) having one active hydrogen in the molecule and a weight average molecular weight of 500 to 20,000. 5. The method for producing microcapsules according to claim 4, which is a reaction product.   The method for producing a microcapsule according to claim 5, wherein the compound (B) is a polyethylene oxide having a hydroxyl group at one end.   The method for producing microcapsules according to claim 5 or 6, wherein the compound (B) is a compound having a melting point of 40 to 180 ° C.   The proportion of the reaction product of the polyfunctional isocyanate (A) having two or more isocyanate groups and the compound (B) having one active hydrogen in the molecule is 10% by mass to 100% by mass with respect to the total isocyanate compounds. The method for producing a microcapsule according to any one of claims 5 to 7. At least one of the isocyanate compounds is a reaction product of a polyfunctional isocyanate (A) having two or more isocyanate groups and a polyether derivative (I) having a terminal amino group represented by the following general formula (I). A method for producing a microcapsule according to claim 4.

[Wherein, X represents —CO— or —SO ₂ —, A represents an arylene or alkylene group, L represents an alkylene group, and R represents an alkyl group, an aryl group or an acyl group. m represents 0 or 1, and n represents a number of 10 to 500 in terms of the average number of moles added of the polyether group. ] The ratio of the reaction product of the polyfunctional isocyanate (A) having two or more isocyanate groups and the polyether derivative (I) having a terminal amino group represented by the following general formula (I) is based on the total isocyanate compounds. The method for producing microcapsules according to claim 9, wherein the content is 10% by mass to 100% by mass.   The method for producing microcapsules according to claim 9 or 10, wherein the polyether derivative (I) is a compound having a melting point of 40 to 180 ° C.   The method for producing a microcapsule according to any one of claims 1 to 11, wherein the particle size of the microcapsule is 0.1 µm to 1.6 µm.   The method for producing microcapsules according to claim 1, wherein the core substance is a diazo compound or an electron donating dye precursor.   The microcapsule obtained by the manufacturing method of any one of Claims 1-13.   15. A recording material comprising a recording layer comprising a microcapsule encapsulating a coloring component on a support, wherein the microcapsule is the microcapsule according to claim 14.