JP2006181855A - Thermal recording color developing agent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color developing agent which has high sensitivity, excellent shelf stability of a recording image, especially excellent humidity resistance at a high temperature/a high humidity, and is almost free from the generation of a texture fog, and a recording material, especially a thermal recording material using this color developing agent. <P>SOLUTION: This thermal recording color developing agent contains a phenol 3 nuclide (B) which is a phenol 3 nuclide (A), as represented by formula (1), having (a) an OH group attached to at least one of the 4- or 4'- position of each of right/left aromatic rings and (b) at least one, as hydrogen, of the substituting groups, adjacent to at least one OH group attached to the right/left aromatic rings as a substituent, and a specific fluoran compound. Besides, this color developing agent has high sensitivity, high temperature/high humidity resistance and is almost free from the generation of a texture fog. Also the thermal recording material is provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a color former composition and a recording material using the color former composition.

  Conventionally, many chemical coloring systems using recording energy such as heat and pressure are known. Among them, a coloring system consisting of a two-component coloring system, usually a colorless or light leuco dye and a developer that develops color when contacted with the leuco dye, has been known for a long time and is widely applied to recording materials. ing. For example, there are pressure-sensitive recording materials using pressure energy, heat-sensitive recording materials using thermal energy, and photosensitive recording materials using light energy.

  There has been a pressure-sensitive recording material using pressure energy, which has been generally used for ordinary paper. In general, the pressure-sensitive recording material is prepared by dispersing a leuco dye in an appropriate medium to prepare an emulsion containing leuco dye particles of several microns, and then preparing microcapsules enclosing the dye particles. The upper sheet coated on top and the lower sheet coated with a developer layer containing a developer on another support so that the microcapsule coating surface and the developer coating surface face each other. Obtained by superposition. When writing pressure or striking pressure is applied to the resulting pressure-sensitive recording material, the microcapsules are destroyed and inclusions containing the leuco dye are released, and the leuco dye is transferred to the developer layer and comes into contact with the developer. Color is developed by chemical reaction, and an image is recorded.

  In recent years, many types of information equipment have adopted a thermal recording system in which recording is performed using thermal energy. The heat-sensitive recording material used in the heat-sensitive recording method has excellent characteristics as a recording material in many respects, such as high whiteness, appearance, touch close to plain paper, and high color development sensitivity. In addition, the thermal recording system is advantageous in that the equipment is small, no maintenance is required, and there is no noise generation. For this reason, measurement recorders, facsimiles, printers, computer terminals, labels, tickets, etc. Applications have been expanded to a wide range of fields such as automatic ticket vending machines.

  The thermal recording method uses a recording material in which a color developing layer mainly containing two types of thermal agent components is provided on a support, and heat as recording energy is applied to this by a thermal head, hot stamp, laser light, or the like. In general, the heat sensitive agent components are brought into contact with each other on the recording material to perform color recording. As the heat-sensitive agent component, many colorants such as colorless or light-colored leuco dyes and acidic developers such as phenolic compounds are used in combination, and recording materials using these include, for example, crystal violet as a color former. Examples include thermal paper using lactone and 2,2-bis (4′-hydroxyphenyl) propane (bisphenol A: BPA) as a developer (see, for example, Patent Document 1).

  As the leuco dye and developer used in these recording methods, mainly an electron donating compound and an electron accepting compound are used, respectively, and they appear close to white before contacting each other. By having this, the concentration is instantaneously high and various colored hues such as red, orange, yellow, green, blue, and black can be obtained. However, on the other hand, the obtained color image disappears, fades under high humidity, and further disappears, so that the storage stability of the color image is inferior, so improvement is strongly desired. .

  In recent years, in particular, with the diversification of recording apparatuses, in particular, with the miniaturization and speeding up of the apparatuses, low color energy (sensitivity) and storage stability of recording quality have been demanded. In order to improve the color developability at low energy, the thermal responsiveness of the thermal recording material is usually improved. Generally, however, if the thermal responsiveness of the thermal recording material is improved, even in the non-heated part on the recording medium. This causes a phenomenon of colored background fogging. Conventionally, methods have been proposed for improving the background fogging and the storage stability of recorded images without impairing thermal responsiveness. In particular, since BPA has excellent thermal responsiveness and background fogging and is inexpensive, it has been widely used as a general-purpose developer for thermal paper for which storage stability of recorded images has not been required so far. Have been put to practical use. However, in recent years, as an endocrine disrupting substance, consideration is being given to conversion to other developers due to environmental safety problems.

  On the other hand, a technique using a condensation polymerization product of a phenol compound and an aldehyde as a developer has been studied mainly in a pressure-sensitive recording material (see Patent Document 2). When this developer is used as a heat-sensitive recording material, there is a problem that the recording image is generally excellent in storage stability but insufficient in sensitivity. In order to solve this problem, various studies have been made to increase sensitivity by using the condensation polymer and the phenol compound together. For example, a thermal recording method is disclosed in which a monomer phenol is used in combination with a condensation polymer of a phenol compound and an aldehyde (see Patent Document 3). The thermosensitive recording method uses a substituted phenol monomer in combination with a condensation polymer of a phenol compound and an aldehyde as a developer, so that the eutectic point is lower than any of the components and the thermal responsiveness is improved. However, this still has a problem that the sensitivity is insufficient in practical use, and when the sensitivity is improved in combination with another developer, a background fog occurs.

  On the other hand, 2,2'-methylenediphenol compound obtained by condensing two molecules of phenol compound with one molecule of formaldehyde as a method for achieving high sensitivity by controlling the degree of condensation of the condensation polymer of phenol compound and aldehyde A heat-sensitive sheet characterized by containing one or more of (phenol dinuclear body) as a developer has been disclosed (see Patent Document 4). However, although the thermal responsiveness of the heat-sensitive sheet is relatively good, the storage stability of the recorded image is poor, and there is a problem with background fogging, which has not been put into practical use.

  On the other hand, for the purpose of improving the storage stability of the recorded image, a heat-sensitive recording material comprising a composition containing the phenol dinuclear as a main component and at least one of phenol polynuclears having 3 to 5 phenols. Developers have been proposed (see Patent Document 5). However, when using a polynuclear phenol, the sensitivity of the recorded image is lowered until the storage stability of the recorded image is practically satisfactory, and the sensitivity equivalent to the BPA currently required in the industry is exhibited. Impossible.

In addition, there is an attempt to use a phenol trinuclear as a developer (see Patent Document 6), but the phenol trinuclear used here generally has a high melting point of 200 ° C. or more and is a subject of the present invention. The sensitivity equivalent to a certain BPA and the storage stability of the recorded image are also insufficient.
Therefore, there is an attempt to improve the sensitivity by reducing the eutectic point to 150 to 200 ° C. by mixing two or more of these phenol trinuclear bodies (see Patent Document 7). A composition containing a phenol trinuclear condensed at the o-position of the OH group cannot provide sufficient sensitivity and storage stability of a recorded image, like the developer of Patent Document 6.

In addition, a novel trinuclear structure in which a p-substituted phenol is condensed with another alkylphenol at the p-position of the OH group via a methylene group at both ortho positions of the hydroxyl group has also been proposed (patent) Also, sufficient sensitivity and storage stability of recorded images are not obtained.
US Pat. No. 3,539,375 Japanese Patent Publication No.42-20144 JP-A-48-58842 Japanese Patent No. 1712000 WO 02/098674 pamphlet Japanese Patent Laid-Open No. 06-115255 JP 2001-96926 A JP 09-278695 A

  The present invention provides a color former having high sensitivity and recording image storage stability, particularly excellent in moisture resistance under high temperature and high humidity, and having little background fogging, and a recording material using the same, particularly a heat sensitive recording material. The purpose is to do.

As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by using a specific phenolic compound and a specific fluorane compound, and have completed the present invention. That is, the present invention
(1) A phenol trinuclear body (A) represented by the following general formula (1), (a) having an OH group in at least one of the 4-, 4′-positions of the left and right aromatic rings,
(B) a developer containing a phenol trinuclear (B), wherein at least one of the adjacent substituents of at least one OH group substituted on the left and right aromatic rings is hydrogen;

(In the formula, _Ra is an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a halogen atom, an aralkyl group having 7 to 14 carbon atoms, and an aryl group. R _b is a group selected from the group consisting of hydrogen, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and a halogen atom, and R _b is a group selected from the group consisting of R _c may be the same as or different from each other, and R _c is hydrogen, halogen atom, cyano group, alkyl group having 1 to 18 carbon atoms, cycloalkyl group having 5 to 10 carbon atoms, alkoxy group having 1 to 4 carbon atoms, carbon number And a group selected from the group consisting of 7 to 14 aralkyl groups and aryl groups, R _c may be the same as or different from each other, and m and n represent an integer of 1 to 5.)
The following general formula (i)

(Here, Y1 and Y2 represent an alkyl group having 2 to 8 carbon atoms and an aralkyl group, and at least one of them has 4 to 8 carbon atoms.)
A color former containing a fluorane compound represented by:
(2) The color former of the invention (1), wherein the content of the phenol trinuclear body (A) and the phenol trinuclear body (C) not corresponding to the phenol trinuclear body (B) is 30 wt% or less,
(3) The ratio of the content of the phenol trinuclear body (B) to the content of the phenol trinuclear body (A) is 0.5 or more, and any one of inventions (1) and (2) Color former,
(4) The color former of any one of inventions (1) to (3), wherein the content of the phenol trinuclear body (A) is 20 wt% or more,
(5) including a condensation product obtained by condensing a p-substituted phenol derivative represented by the following general formula (2) and at least one of the phenolic compounds represented by the following general formula (3), The color former according to any one of inventions (1) to (4), wherein the content of the condensation product component other than the phenol trinuclear (A) contained in the condensation product is 50 wt% or less,

(In the formula, R _d is an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a halogen atom, an aralkyl group having 7 to 14 carbon atoms, and an aryl group. R _e is a group selected from the group consisting of hydrogen, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and a halogen atom, and R _e is the same as each other But it may be different.)

(In the formula, R _f is hydrogen, hydroxyl group, halogen atom, cyano group, alkyl group having 1 to 18 carbon atoms, cycloalkyl group having 5 to 10 carbon atoms, alkoxy group having 1 to 4 carbon atoms, or 7 to 14 carbon atoms. And R _f may be the same or different from each other.)

(6) R _{a in the} general formula (1) is an alkyl group having 2 to 18 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a halogen atom, and an aralkyl having 7 to 14 carbon atoms. A coloring agent according to any one of inventions (1) to (5), wherein the coloring agent is a group selected from the group consisting of a group and an aryl group, and R _c is all hydrogen;
(7) The color formers of any one of inventions (1) to (6), wherein R _f in general formula (3) is all hydrogen,
(8) A recording material comprising the color developer of any one of inventions (1) to (7) on a support,
(9) The recording material according to the invention (8), wherein the recording material is a thermosensitive recording material.

  According to the developer of the present invention and the heat-sensitive recording material using the same, it is possible to obtain a heat-sensitive recording material having high sensitivity and excellent moisture resistance under high temperature and high humidity, which has been difficult in the past, and having less background fog. It becomes possible.

  As shown in the general formula (1), the developer used in the present invention has a structure in which a p-substituted phenol nucleus is bonded to two other phenol nuclei via a methylene group at both ortho positions of the OH group. At least one OH which is a phenol trinuclear body (A), which has an OH group in at least one of the 4-, 4'-positions of the left and right aromatic rings and is substituted with the left and right aromatic rings Contains a phenol trinuclear (B) characterized in that at least one of the adjacent substituents of the group is hydrogen.

  In the phenol trinuclear body (B) of the present invention, it is important to have an OH group in at least one of the 4-, 4'-positions of the left and right aromatic rings. For example, when there is no OH group at the 4-, 4'-position of the left and right aromatic rings and only at the 2-, 2'-position of the left and right aromatic rings, the central position is at the ortho position of the OH group. Since the aromatic ring is present via the methylene group, the OH group that plays the main role in color development is affected by the steric influence of the adjacent linking group, resulting in insufficient color development sensitivity and storage stability of the recorded image.

  In the phenol trinuclear body (B) of the present invention, it is important that at least one of adjacent substituents of at least one OH group substituted on the left and right aromatic rings is hydrogen. Here, “adjacent substituent of OH group” means a substituent or atom bonded to two carbon atoms adjacent to the carbon to which the OH group is bonded in the aromatic ring. When the adjacent substituents of the OH group in the left and right aromatic rings of the phenol trinuclear body (A) are all other than hydrogen atoms, when this is used as a developer component of the color former composition, the OH group Since the interaction of the leuco dye as the color former component is hindered by the adjacent substituent of the OH group, it is difficult to obtain a color former composition having sufficient sensitivity and recording image storage stability.

The phenol trinuclear body (B) of the present invention will be described more specifically.
R _a in the general formula (1) is an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a halogen atom, an aralkyl group having 7 to 14 carbon atoms. And a group selected from the group consisting of aryl groups, preferably having 2 or more carbon atoms, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, t-butyl group, dodecyl group Cyclohexyl group, phenyl group, α methylbenzyl group, α, α ′ dimethylbenzyl group, more preferably n-propyl group, isopropyl group, n-butyl group, sec-butyl group, t-butyl group, cyclohexyl group. , Phenyl group, α-methylbenzyl group, α, α ′ dimethylbenzyl group.

R _b is a group selected from the group consisting of hydrogen, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and a halogen atom, preferably hydrogen or a methyl group, and R _b May be the same as or different from each other.
_Rc is hydrogen, a halogen atom, a cyano group, an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an aralkyl group and an aryl group having 7 to 14 carbon atoms. A group selected from the group consisting of hydrogen, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, t-butyl group, dodecyl group, cyclohexyl group, It is a phenyl group, and R _{c s} may be the same as or different from each other, and particularly preferably, all R _c are hydrogen.
m and n are integers of 1 to 5 and represent the number of OH groups substituted on the left and right aromatic rings. Generally, as the number of OH groups increases, the water solubility increases, and the mixture is mixed in a leuco dye and an aqueous dispersion medium. Preferably, m, n = 1 or 2 because coloring easily occurs at the stage of forming the color former composition, or the background is covered with a moisture resistance test.

  In the developer of the present invention, the phenol trinuclear body (B) is an essential component, but other than the essential components for the purpose of reducing the melting point of the developer and increasing the color development sensitivity of the resulting recording material. As a component, a phenol trinuclear body (A) that does not correspond to the phenol trinuclear body (B) may be included. However, if the content of the phenol trinuclear (C) in the developer is high, it may be disadvantageous in the color development performance and the recorded image storage performance, so the content is preferably 30 wt% or less. More preferably, it is 25 wt% or less, More preferably, it is 20 wt% or less. As the phenol trinuclear body (C), for example, what corresponds to the isomer of the phenol trinuclear body (B) having an OH group only at the 2-, 2′-position of the left and right aromatic rings will be described later. Thus, since it can prepare simultaneously with a phenol trinuclear body (B) by the same chemical reaction operation, it is preferable from a viewpoint of an efficient color developer manufacturing method.

As described above, when the developer of the present invention contains phenol trinuclear bodies (B) and (C), the content of phenol trinuclear body (B) in the developer is phenol trinuclear body (A). It is preferable that the ratio with respect to the content rate of is 0.5 or more. The higher the content of the phenol trinuclear body (B), the easier it is to achieve the effects of the present invention. More preferably, it is 0.6 or more.
As will be described later, the developer of the present invention may contain various components other than the above-described phenol trinuclear (A) component as long as the effects of the present invention are not impaired. Since the colorant is particularly effective for the expression of the target performance, the colorant preferably contains 20 wt% or more of the phenol trinuclear body (A), more preferably 50 wt%, still more preferably 70 wt% or more.

  The method for preparing the phenol trinuclear body (B) of the present invention is not particularly limited theoretically. A method of condensing various phenolic compounds with formaldehyde is generally known as a simple method. However, when it is intended to obtain a phenol trinuclear body comprising different types of phenol nuclei as in the present invention by such a method, the resulting condensation product becomes a mixture of a large number of phenol condensation products, and the desired phenol trinuclear body is obtained. It is difficult to obtain (B) efficiently. Therefore, it is preferable to condense the p-substituted phenol derivative represented by the general formula (2) and at least one of the phenolic compounds represented by the general formula (3).

It is relatively easy to make the condensation product obtained by the above method into a mixture of phenol trinuclear bodies (B) and (C) by controlling reaction conditions. This means that the phenol trinuclear bodies (B) and (C) can be prepared simultaneously by a single chemical reaction operation, and the high melting point phenol polynuclear body having a similar molecular structure as shown in the prior art. Are separately synthesized in advance and then mixed to use them as a developer.
Furthermore, the superior point of the above method is that the condensation product includes condensation product components other than the phenol trinuclear (A) (hereinafter, referred to as a condensation by-product as appropriate). The obtained condensation product can be used as a developer almost as it is without performing special purification and fractionation operations for removing by-products. Of course, for the purpose of further improving the performance of the developer, purification or the like may be performed by the method described below.

In addition, as a condensation by-product here, the high molecular weight component which a p-substituted phenol derivative shown by general formula (2) reacts with the target compound shown by general formula (1) further, for example is produced | generated. Or a component obtained by condensation of a dihydroxymethyl compound contained in the process of preparation of the same p-substituted phenol derivative or a monohydroxymethyl compound and a phenolic compound represented by the general formula (3). Can be mentioned.
In this case, the content of the condensation by-product in the developer of the present invention is preferably 50 wt% or less. If the amount is higher than this, the melting start temperature of the developer and the melting point are lowered, so that depending on the use of the recording agent, sufficient heat resistance may not be obtained, and problems such as the occurrence of background fogging may occur. . More preferably, it is 20 wt% or less, More preferably, it is 10 wt% or less, More preferably, it is 5 wt% or less.

The p-substituted phenol derivative represented by the general formula (2) used in the above preparation method is a dihydroxymethylated corresponding p-substituted phenol, in which R _d is an alkyl group having 1 to 18 carbon atoms. , A cycloalkyl group having 5 to 10 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a halogen atom, an aralkyl group having 7 to 14 carbon atoms, and an aryl group, preferably 2 carbon atoms. Ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, t-butyl group, dodecyl group, cyclohexyl group, phenyl group, α methylbenzyl group, α, α 'dimethylbenzyl group More preferably, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, t-butyl group, cyclohexyl group, phenyl group, α-methyl group Jill groups, alpha, is alpha 'dimethylbenzyl group. R _e is a group selected from the group consisting of hydrogen, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and a halogen atom, and R _e may be the same as or different from each other. Of these, hydrogen or a methyl group is preferable.

  Such as, for example, 2,6-dihydroxymethyl-4-methylphenol, 2,6-dihydroxymethyl-4-ethylphenol, 2,6-dihydroxymethyl-4-n-propylphenol, 2,6- Dihydroxymethyl-4-isopropylphenol, 2,6-dihydroxymethyl-4-t-butylphenol, 2,6-dihydroxymethyl-4-sec-butylphenol, 2,6-dihydroxymethyl-4-n-butylphenol, 2,6 -Dihydroxymethyl-4-dodecylphenol, 2,6-dihydroxymethyl-3,4,5-trimethylphenol, 2,6-dihydroxymethyl-4-cyclohexylphenol, 2,6-dihydroxymethyl-4-methoxyphenol, 2 , 6-Dihydroxymethyl-4-bu Xylphenol, 2,6-dihydroxymethyl-4-t-amylphenol, 2,6-dihydroxymethyl-4-phenylphenol, 2,6-dihydroxymethyl-4- (α-methylbenzyl) phenol, 2,6- Examples include dihydroxymethyl-3-methyl-4-isopropylphenol, 2,6-dihydroxymethyl-4- (α, α′-dimethylbenzyl) phenol, and preferably 2,6-dihydroxymethyl-4-ethylphenol. 2,6-dihydroxymethyl-4-n-propylphenol, 2,6-dihydroxymethyl-4-isopropylphenol, 2,6-dihydroxymethyl-4-tert-butylphenol, 2,6-dihydroxymethyl-4-sec -Butylphenol, 2,6-dihydroxymethyl-4-n-butyl Ruphenol, 2,6-dihydroxymethyl-4-dodecylphenol, 2,6-dihydroxymethyl-3,4,5-trimethylphenol, 2,6-dihydroxymethyl-4-cyclohexylphenol, 2,6-dihydroxymethyl- 4-methoxyphenol, 2,6-dihydroxymethyl-4-butoxyphenol, 2,6-dihydroxymethyl-4-t-amylphenol, 2,6-dihydroxymethyl-4-phenylphenol, 2,6-dihydroxymethyl- 4- (α-methylbenzyl) phenol, 2,6-dihydroxymethyl-3-methyl-4-isopropylphenol, 2,6-dihydroxymethyl-4- (α, α′-dimethylbenzyl) phenol.

  Dihydroxymethylation of these p-substituted phenols can be carried out by a conventional method. For example, p-substituted phenol and formaldehyde are reacted in the presence of water and a basic catalyst, and the reaction product is reacted with an acid. It can be obtained by neutralization or acidification.

On the other hand, the phenolic compound condensed with the p-substituted phenol derivative is represented by the general formula (3). In formula (3), R _f is selected from hydrogen, a hydroxyl group, a halogen atom, a cyano group, an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, an aralkyl group having 7 to 14 carbon atoms, and an aryl group. R _f may be the same or different from each other.
Among the phenolic compounds having the molecular structure represented by the formula (3), by using a compound in which R _f is appropriately hydrogen, the adjacent substituents of at least one OH group substituted on the left and right aromatic rings A phenol trinuclear body (A) in which at least one of them is hydrogen can be obtained.

Moreover, since the phenolic compound represented by Formula (3) has high condensation reaction activity at the para position of the OH group in the formula, it has an OH group at at least one of the 4- and 4'-positions of the left and right benzene rings. The phenol trinuclear body (A) can be obtained relatively easily.
Examples of such phenolic compounds include phenol, o-cresol, m-cresol, 2-ethylphenol, 3-ethylphenol, 2-isopropylphenol, 3-isopropylphenol, 2-sec-butylphenol, and 2-tert. -Butylphenol, 3-tert-butylphenol, 2-phenylphenol, 3-phenylphenol, 2-chlorophenol, 3-chlorophenol, 2-bromophenol, 3-bromophenol, 2-cyanophenol, 3-cyanophenol, 2 , 3-dimethylphenol, catechol, resorcin and the like.

Among these, from the viewpoint of the performance of the obtained developer and being inexpensive and easy to obtain, preferred are phenol having a substituent only at the 3-position and / or the 5-position and all R _f are hydrogen atoms. An unsubstituted phenol. In addition, since catechol and resorcin also have two OH groups, it is convenient to obtain a high-sensitivity developer, but on the other hand, since it has many hydrophilic substituents in the molecule, its water solubility becomes high. Coloring occurs at the stage of mixing the leuco dye with an aqueous dispersion medium to form a color former composition, or the background is covered with a moisture resistance test. Therefore, when using these phenolic compounds, it is preferable to select p-substituted phenol derivatives represented by the formula (2) having high hydrophobicity as the substituents R _d and R _e .

  Using the p-substituted phenol derivative and the phenolic compound, the developer composition of the present invention can be prepared according to a conventionally known method. For example, when a predetermined amount of the above p-substituted phenol derivative and a phenolic compound are heated and reacted in the presence of an appropriate acid catalyst, condensation of both occurs, and the phenol trinuclear (A) represented by the general formula (1) ) As a main component. In this condensation reaction, generally, the phenolic compound has a high reaction activity at the para-position and the ortho-position with respect to the OH group represented by the formula (3). As a result, the obtained phenol trinuclear body (A) The mixture of the phenol trinuclear body (B) and the phenol trinuclear body (C) can be made relatively easily.

  Here, by adjusting the molar ratio of the phenolic compound to the p-substituted phenol derivative used in the condensation reaction, the content of the condensation by-product in the developer can be controlled. For example, when the content of the condensation by-product is 50 wt% or less, the phenolic compound is preferably used in an amount of 10-fold mol or more, preferably 20-fold mol or more based on the p-substituted phenol derivative. Alternatively, a p-substituted phenol derivative can be sequentially added into a reaction system containing a phenolic compound charged in advance.

The condensation product thus obtained can be used as a developer as it is, but in particular, when the purity of the developer is required, a general purification method, if necessary, For example, once the condensation product is dissolved in a good solvent, it is added to a poor solvent and reprecipitated, or the product is washed with a solvent in which other condensate is dissolved, and the product is dissolved in a solvent by heating. Then, after purification by cooling and recrystallization, the developer may be used as a developer.
The specific fluorane compound used with the specific developer of the present invention is represented by the following general formula (i)

(Here, Y1 and Y2 represent an alkyl group having 2 to 8 carbon atoms and an aralkyl group, and at least one of them has 4 to 8 carbon atoms.)
It is represented by Among these, Y1 is preferably an alkyl group having 2 to 5 carbon atoms, and Y2 is preferably an alkyl group having 4 to 5 carbon atoms.

In addition, this fluorane compound can use 2 or more types together as needed.
Examples of other developers that can be used in combination with the developer of the present invention include phenol derivatives, hydroxybenzoic acid derivatives, salicylic acid derivatives, sulfonylurea compounds, sulfonylamide compounds, and urea urethane compounds represented by the general formula (4). . Hereinafter, although each specific example is shown, it is not limited to these.

(In Formula (4), the hydrogen atom bonded to the aromatic ring may be substituted with a hydroxyl group, an alkyl group, an aryl group, an alkoxy group, a phenyl group, or a substituted phenyl group, and A represents —CR ¹ R ² —, —SO ₂ —, —O—, —CO—, —CONH—, —NH—, —OCOO—, —NHCONH—, —NHCOO—, —CH (COOR ³ ) —, —C (CF ₃ ) ₂ —, -OCH ₂ CH ₂ O- and one selected from a cyclohexylidene group, R ¹ , R ² , and R ³ each represent hydrogen, an alkyl group, and a phenyl group, B represents a hydroxyl group, an alkoxy group, and (It is one selected from the groups represented by the following formula (5).)

(In Formula (5), p is an integer of 1-7.)
Examples of the phenol derivative represented by the general formula (4) include 2,2-bis (4′-hydroxyphenyl) propane, 2,2-bis (hydroxyphenyl) butane, 2,2-bis (hydroxyphenyl) heptane, 4,4 '-(1,3-dimethyl-butylidene) bisphenol, 1,1-bis (4-hydroxyphenyl) cyclohexane, butyl bis (4-hydroxyphenyl) acetate, benzyl bis (4-hydroxyphenyl) acetate, 4 , 4 '-(1,3-dimethyl-butylidene) bisphenol, 2,4-dihydroxy-2'-methoxy-benzanilide, n-butyl-bis (4-hydroxyphenyl) acetate, 1- (4-carboxy-3- Hydroxyphenoxy) -2- (4-methoxyphenoxy) ethane, 4,4'-dihydroxydiphe Nylsulfone, bis (3-methyl-4-hydroxyphenyl) sulfone, 4-hydroxyphenyl-4′-methylphenylsulfone, 3-chloro-4-hydroxyphenyl-4′-methylphenylsulfone, 3,4-dihydroxyphenyl- 4'-methylphenylsulfone, 2,4'-dihydroxydiphenylsulfone, bis- (3-allyl-4-hydroxyphenyl) sulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone, 4-hydroxyphenyl-4'- Benzyloxyphenylsulfone, 4-isopropylphenyl-4'-hydroxyphenylsulfone, bis (2-methyl-3-tert-butyl-4-hydroxyphenyl) sulfide, 1- (4'methoxyphenyloxy) 2- (3 ' Hydroxy-4 'carboxyph Niruokishi) ethane, 4,4 'oxybis (ethyleneoxy -p- phenylene sulfone) developer mainly composed of diphenols (manufactured by Nippon Soda Co., Ltd.: D-90), and the like.

Examples of hydroxybenzoic acid derivatives include methyl 4-hydroxybenzoate, ethyl 4-hydroxybenzoate, butyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate, 4-hydroxybenzoic acid (4′-chlorobenzyl), 1, Examples include 2-bis (4′-hydroxybenzoic acid) ethyl, 1,5-bis (4′-hydroxybenzoic acid) pentyl, 1,6-bis (4′-hydroxybenzoic acid hexyl), and the like.
Examples of the salicylic acid derivative include 4-n-octyloxysalicylic acid, 4-n-butyloxysalicylic acid, 4-n-pentyloxysalicylic acid, 3-n-dodecyloxysalicylic acid, 3-n-octanoyloxysalicylic acid, 4-octyl. Examples thereof include oxycarbonylaminosalicylic acid, 4-n-octanoyloxycarbonylaminosalicylic acid, and the like, and metal salts thereof.

Examples of the sulfonylurea compound include Np-toluenesulfonyl-N′-3- (p-toluenesulfonyloxy) phenylurea (PF-201 manufactured by Ciba Specialty Chemicals), 4,4′-bis (p-toluenesulfonylamino). Carbonylamino) diphenylmethane, 4,4′-bis (p-toluenesulfonylaminocarbonylamino) diphenyl sulfide, 4,4′-bis (p-toluenesulfonylaminocarbonylamino) diphenyl ether, N- (p-toluenesulfonyl) -N Also included are compounds containing at least one arylsulfonylaminoureido group such as' -phenylurea.
Moreover, as a urea urethane compound, it is prescribed | regulated by international publication 00/14058 pamphlet and Unexamined-Japanese-Patent No. 2002-332271, For example, the color developer UU by Asahi Kasei Chemicals Corporation etc. is mentioned.

  In addition, two or more types of these other developers used in combination with the developer of the present invention can be used in combination as required. Although these other color developers generally have few sensitivities and storage stability of recorded images, they are disadvantageous in that they are expensive and inferior in economy. Can be mixed and used in combination with the developer of the present invention, so that practically satisfactory performance in sensitivity, storage stability of recorded images, background fogging, and economic efficiency can be expressed.

  About the usage-amount of the color developer in the color former composition of this invention, 5-1000 weight part is normally used with respect to 100 weight part of fluorane compounds of this invention, Preferably it is 10-500 weight part, More preferably 30 to 300 parts by weight are used. If the amount of the developer is small, the color density is too low to be put to practical use. If the amount of the developer is too large, the color density reaches a saturation value, which is economically disadvantageous.

  When the color former composition of the present invention is used as a heat-sensitive recording material, a sensitizer can be contained in the color former composition for the purpose of improving the sensitivity of the recording material. The sensitizer is generally a chemical substance that can be melted by heat, and preferably has a melting point of 60 ° C to 180 ° C, and particularly preferably has a melting point of 80 ° C to 140 ° C. For example, stearic acid amide or emulsion thereof, palmitic acid amide, behenic acid amide, N-methylol stearic acid amide, β-naphthylbenzyl ether, N-stearyl urea, N, N′-distearyl urea, β-naphthoic acid phenyl Ester, 1-hydroxy-2-naphthoic acid phenyl ester, β-naphthol (p-methylbenzyl) ether, 1,4-dimethoxynaphthalene, 1-methoxy-4-benzyloxynaphthalene, N-stearoyl urea, p-benzylbiphenyl 1,2-diphenoxyethane, 1,2-di (m-methylphenoxy) ethane, 1,2-diphenoxymethylbenzene, 1,2-bis (3,4-dimethylphenyl) ethane, 1-phenoxy- 2- (4-Chlorophenoxy) ethane, 1,4-butanedio Phenyl ether, dimethyl terephthalate, dibenzyl terephthalate, meta-terphenyl, oxalic acid dibenzyl oxalate, di -p- methylbenzyl ester, oxalic acid di (p- chlorobenzyl) ester.

Furthermore, 4,4′-dimethoxybenzophenone, 4,4′-dichlorobenzophenone, 4,4′-difluorobenzophenone, diphenylsulfone, 4,4′-dichlorodiphenylsulfone, 4,4′-difluorodiphenylsulfone, 4,4 '-Dichlorodiphenyl disulfide, diphenylamine, 2-methyl-4-methoxydiphenylamine, N, N'-diphenyl-p-phenylenediamine, 1- (N-phenylamino) naphthalene, 1,3-diphenyl-1,3-propane Dione or the like is preferable because it has the effect of improving the sensitivity of the recording material.
Of these, preferably diphenyl sulfone, oxalic acid di-p-methylbenzyl ester, p-hydroxybenzoic acid benzyl, β-naphthylbenzyl ether, p-benzylbiphenyl, 1,2-di (m-methylphenoxy) ethane, 1,2-diphenoxymethylbenzene, metaterphenyl, stearamide is used.

  The above sensitizers may be used alone or in combination of two or more. Moreover, the usage-amount is 0-1000 weight part normally with respect to 100 weight part of fluorane compounds of this invention, Preferably it is 0-500 weight part, More preferably, 1-300 weight part is used. If the amount of the sensitizer is small, it is difficult to increase the thermal response of the recording material. Conversely, if the amount of the sensitizer is too large, the thermal response reaches a saturation value, which is economically disadvantageous.

  As described above, the color former of the present invention comprises the developer of the present invention and a fluorane compound as essential components, and a sensitizer is used in combination as necessary. Other additives such as lubricants, binders, fillers, dispersants, preservability-imparting agents and the like as described can also be included in the color former composition of the present invention.

Lubricants are added for the purpose of preventing thermal head wear and sticking, etc. Waxes such as animal and vegetable waxes and synthetic waxes, higher fatty acids and their metal salts, higher fatty acid amides, higher fatty acid anilides, etc. It is solid at room temperature and has a melting point of about 70 ° C. or higher. Specific examples of waxes include, for example, wood wax, carnauba wax, shellac, paraffin, montan wax, oxidized paraffin, polyethylene wax, polyethylene oxide, etc. Specific examples of higher fatty acids and metal salts thereof include stearic acid, Specific examples of higher fatty acid amides such as behenic acid and metal salts thereof such as zinc stearate and calcium stearate include oleic acid amide, N-methyl stearic acid amide, erucic acid amide, methylol behenic acid amide, methylene bis Examples of higher fatty acid anilides such as stearic acid amide and ethylenebisstearic acid amide include stearic acid anilide and linoleic acid anilide.
Any amount of these lubricants can be used, but it is preferably no more than twice the amount of leuco dye used.

  Specific examples of the binder that can be used in the present invention include, for example, methylcellulose, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, sodium carboxymethylcellulose, cellulose, polyvinyl alcohol, carboxy-modified polyvinyl alcohol, sulfonic acid group-modified polyvinyl alcohol, polyvinylpyrrolidone, poly Acrylamide, polyacrylic acid, starch or derivatives thereof, casein, gelatin, water-soluble isoprene rubber, alkali salt of styrene / maleic anhydride copolymer, alkali salt of iso (or diiso) butylene / maleic anhydride copolymer, etc. Water-soluble or polyvinyl acetate, vinyl chloride / vinyl acetate copolymer, polystyrene, polyacrylate, polyurethane, styrene / butadiene copolymer , Carboxylated styrene / butadiene copolymers, styrene / butadiene / acrylic acid copolymer, colloidal silica and a hydrophobic polymer emulsion such as composite particles of the acrylic resin is used.

  Specific examples of the filler that can be used in the present invention include, for example, calcium carbonate, magnesium carbonate, magnesium oxide, silica, white carbon, talc, clay, alumina, magnesium hydroxide, aluminum hydroxide, aluminum oxide, barium sulfate, and polystyrene resin. And urea-formalin resin. The added amount of the filler is 0 to 1000 parts by weight, preferably 0 to 500 parts by weight, and more preferably 0 to 300 parts by weight with respect to 100 parts by weight of the leuco dye.

  Specific examples of the dispersant that can be used in the present invention include polyvinyl alcohol, carboxylic acid-modified polyvinyl alcohol, sulfonic acid-modified polyvinyl alcohol, methylcellulose, hydroxypropylmethylcellulose, hydroxypropylcellulose, and styrene maleic anhydride copolymer alkali salt. Water-soluble polymers such as condensed naphthalene sulfonate, polyoxyethylene alkyl ether sulfate ester salt (for example, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate), Sodium dialkylsulfosuccinate, alkyl phosphate (eg, diethanolamine alkyl phosphate, potassium alkyl phosphate), In particular, anionic surfactants such as carboxylic acid type polymers, nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene sorbitan fatty acid ester, fatty acid monoglyceride, polyethylene glycol fatty acid ester, di Mention may be made of cationic surfactants such as cyanamide polyamines, tertiary amine salts and quaternary ammonium salts. Among these, polyvinyl alcohol, carboxylic acid-modified polyvinyl alcohol, sulfonic acid-modified polyvinyl alcohol, alkali salt of styrene maleic acid copolymer, methyl cellulose, and sodium polyoxyethylene alkyl ether sulfate are particularly preferable. These can be used alone or in combination.

  The preservability-imparting agent that can be used in the present invention is an additive such as an image stabilizer, a light stabilizer, and an antioxidant. By using these preservatives in combination with the color former of the present invention, the light resistance of the color former can be improved, and a recording material having excellent light resistance can be obtained. Examples of the image stabilizer as a preferred example of the preservability-imparting agent used in the present invention include 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,1 , 3-Tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, 4,4′-butylidenebis (2-tert-butyl-5-methylphenol), 4,4′-thiobis (2-tertiary) Hindered phenols such as butyl-5-methylphenol), 2,2'-thiobis (6-tert-butyl-4-methylphenol), 2,2'-methylenebis (6-tert-butyl-4-methylphenol) Compound, 4-benzyloxy-4 '-(2-methylglycidyloxy) diphenylsulfone, 4,4'-diglycidyloxydiphenylsulfone, 1,4-dig Examples thereof include sidyloxybenzene, sodium-2,2′-methylenebis (4,6-ditertiarybutylphenyl) phosphate, 2-propanol derivatives, salicylic acid derivatives, and the like. Preferably it is 5-1000 weight part with respect to 100 weight part of fluorane compounds, More preferably, 10-500 weight part is used. If the image stabilizer is 5 parts by weight or more, the light resistance is good and the color density is high.

Further, if the amount of the image stabilizer is more than 1000 parts by weight, the effect on light resistance is not improved, and it is economically disadvantageous.
Whiteness may be improved by adding a fluorescent dye to the color former of the present invention. As the fluorescent dye, various known dyes can be used, and examples thereof include, but are not limited to, stilbene derivatives, coumarin derivatives, pyrazoline derivatives, bisstyryl biphenyl derivatives, naphthalimide derivatives, bisbenzoxazolyl derivatives, and the like. However, a diaminostilbene disulfonic acid derivative is particularly preferable. About the usage-amount of a fluorescent dye, it is preferable to make it exist 0.01-3 weight% with respect to the total solid amount of a color former, More preferably, it is the range of 0.1-2 weight%. When the amount of the fluorescent dye used exceeds 3% by weight, the color former may be colored, and when it is less than 0.01% by weight, the effect on the whiteness is lowered.

The color former of the present invention can be used for various recording materials such as a heat-sensitive recording material and a pressure-sensitive recording material, and is particularly suitable as a heat-sensitive recording material.
As a heat-sensitive recording material, a material having a structure in which a heat-sensitive recording layer for heating and coloring is provided on a support is generally used. More specifically, a color developer, a fluorane compound, a heat-fusible compound or the like is applied in the form of a dispersion together with other necessary components on the support to form a heat-sensitive recording layer. The dispersion is prepared by pulverizing one or more of these components in an aqueous solution containing a dispersant using a sand grinder or the like. The particle diameter of the dispersed particles contained in the dispersion is preferably in the range of 0.1 to 10 μm, and more preferably around 1 μm.

When the developer of the present invention is used for a heat-sensitive recording material, a finely pulverized developer particle having an average particle size of 0.05 μm or more and 5 μm or less has good thermal responsiveness, and a colored recorded image A heat-sensitive recording material having good storage stability can be obtained. When the average particle size is less than 0.05 μm, the background preservation property is deteriorated, while when the average particle size is 5 μm or more, the sensitivity of the heat-sensitive recording material is lowered. More preferably, it is 0.1 μm or more and 3 μm or less.
The liquid temperature of the aqueous medium used when wet-pulverizing the developer of the present invention in an aqueous medium is preferably 60 ° C. or lower. If the liquid temperature is 60 ° C. or higher, the developer may be denatured and aggregated depending on other conditions, which may cause background fogging or a decrease in sensitivity of the heat-sensitive recording material used.

When the developer is pulverized, it is desirable to pulverize in a neutral region having a pH of 5 to 10. If the pH at the time of pulverization is less than 5, when preparing a thermal coating liquid, the inorganic pigments may be decomposed and the sensitivity may be lowered. On the other hand, if the pH is greater than 10, the developer may be modified and the sensitivity may be lowered. .
Further, when the developer is pulverized, the reason is not necessarily clear as compared to the case where each agent is separately pulverized separately by mixing by pulverizing (co-pulverizing) simultaneously with the sensitizer. However, the sensitivity of the heat-sensitive recording material is further improved, and the effect of improving the recording storage stability can be obtained.

As the support for the heat-sensitive recording layer, paper is mainly used. In addition to paper, various woven fabrics, non-woven fabrics, synthetic resin films, laminated papers, synthetic papers, metal foils, or composite sheets combining these are used depending on the purpose. Can be used arbitrarily. As the basis weight of the support, desirably ^{40g / m 2 ~200g / m 2} , since the highest possible flatness as heat-sensitive recording material is one having excellent smoothness and flatness of the surface since it is desirable that desired, machine calender The surface treatment is preferably performed by applying heat and pressure with a soft calender, a super calender or the like.
Moreover, it is preferable that the surface pH of a support body is 3-12. If the surface pH of the support is less than 3, background fog tends to occur, and if it exceeds 12, the developer may be denatured and the color density may decrease. More preferably, it is pH 5-9, More preferably, it is pH 6-8.

  The thermosensitive recording layer may be composed of a single layer or a plurality of layers. For example, each color forming component may be contained one by one to form a multilayer structure. Further, a protective layer composed of one layer or a plurality of layers may be provided on the thermosensitive recording layer, or an intermediate layer composed of one layer or a plurality of layers may be provided between the support and the thermosensitive recording layer. Good. This heat-sensitive recording layer can be obtained by mixing each aqueous dispersion obtained by finely pulverizing each color forming component or other components, a binder and the like, and applying and drying on a support.

The color former of the present invention can be used as various thermosensitive recording materials, and is particularly suitable as a thermosensitive magnetic recording material, a thermosensitive recording label, a multicolor thermosensitive recording material, and a thermosensitive recording material for laser marking. In the case where the heat-sensitive recording material is a heat-sensitive magnetic recording material, a form in which a heat-sensitive recording layer containing a developer is provided on one side of the support and a magnetic recording layer is provided on the other side is preferable. The magnetic recording layer in the heat-sensitive magnetic recording material uniformly disperses ferromagnetic powder such as barium ferrite, strontium ferrite, Co-γ-Fe ₂ O ₂ and γ-Fe ₂ O _{2 in} an aqueous binder such as an aqueous emulsion resin. The coated material is applied onto a support and dried to form a magnetic recording layer. At this time, various additives such as polyethylene oxide and the like may be added as an antistatic agent such as carbon graphite, a wax as a lubricant, a color pigment for adjusting a hue, and a film softening agent depending on the purpose. The heat-sensitive magnetic recording material of the present invention is suitable as a heat-sensitive magnetic recording material such as a ticket, a ticket, or a prepaid card.

  When the heat-sensitive recording material is a heat-sensitive recording label, a form in which a heat-sensitive recording layer containing a developer is provided on one side of the support and an adhesive layer is provided on the other side is preferable. The pressure-sensitive adhesive layer of the heat-sensitive recording material has a pressure-sensitive adhesive as a main component. Examples of the pressure-sensitive adhesive include a synthetic rubber-based emulsion-type pressure-sensitive adhesive, an acrylic emulsion-type pressure-sensitive adhesive, a natural rubber-based solvent-type pressure-sensitive adhesive, Acrylic solvent-type pressure-sensitive adhesives and silicon-based solvent-type pressure-sensitive adhesives are exemplified, and acrylic emulsion-type pressure-sensitive adhesives are particularly preferable.

In addition, the thermosensitive recording label produced by the method of the present invention is provided with a back layer (backcoat layer) between the pressure-sensitive adhesive layer and the support, if necessary, to correct curling, antistatic, and friction of the thermosensitive recording label. The coefficient can be adjusted. As the coating liquid component and the coating method for the back surface layer, the same method as the method for forming the heat-sensitive recording layer can be used.

  There are no particular restrictions on the order of application in producing the thermal recording label. For example, after the thermal recording layer is provided on the support, a backcoat layer is provided on the other side, and an adhesive layer is further provided. Alternatively, it is possible to prepare by providing a back coat layer on the support, then providing a thermosensitive recording layer on the other side, and further providing an adhesive layer on the back coat layer.

  In addition, as a method of providing the adhesive layer on the backcoat layer, the adhesive layer solution may be directly applied on the backcoat layer and dried, or the adhesive layer solution is previously applied and dried on a release paper, The back coat layer side of the heat-sensitive recording material before providing the agent layer may be laminated. Furthermore, an intermediate layer composed of one layer or a plurality of layers can be provided between the thermosensitive recording layer and the support to improve the thermal response. The intermediate layer is mainly composed of organic, inorganic pigments, hollow particles, and water-based binders such as water-soluble polymers and latexes, and the same organic and inorganic pigments and water-based binders as the heat-sensitive recording layer can be used. The method for forming the intermediate layer is not particularly limited, and a method similar to the method for forming the thermosensitive recording layer can be used.

  In addition, the heat-sensitive recording layer of the heat-sensitive recording label contains as a main component a color former and an adhesive that cause a color reaction based on contact of the substance by heating, and a crosslinking agent, pigment, and sensitizer are added as necessary. can do. In this application, as the adhesive contained in the thermosensitive coloring layer, either a water-soluble resin or a water-dispersible resin can be used. However, when mixed with each dispersion of the leuco dye and the color developing composition, it is necessary that the mixed solution does not develop color, aggregate, or become high viscosity, and the formed thermal recording. The layer coating must be tough and have no desensitizing action. The amount of the adhesive in the thermosensitive coloring layer is preferably 5 to 20% with respect to the solid content of the thermosensitive coloring layer. If it is less than 5%, the coating strength is low, and if it exceeds 20%, the sensitivity decreases. There is. Moreover, in order to improve the water resistance of the thermosensitive coloring layer, a crosslinking agent for curing the resin can be used.

  When the heat-sensitive recording material is a multicolor heat-sensitive recording material, at least two heat-sensitive recording layers are provided on one surface of the support, and the developer of the present invention is contained in at least one of the heat-sensitive recording layers. Form is preferred. The support to be used is obtained by heating and kneading a polyolefin resin and a white inorganic pigment, then extruding from a die and stretching the film in the longitudinal direction, and laminating one or two films of a polyolefin resin and a white inorganic pigment on both sides. Synthetic paper produced by stretching in the transverse direction to make it translucent or opaque, and a thermoplastic resin such as polyethylene, polypropylene, ethylene-vinyl acetate copolymer resin, polyvinyl chloride, polystyrene, polyester, or a mixture thereof. In addition to films obtained by biaxial stretching by extrusion from a die after heating and kneading, and opaque films biaxially stretched after mixing white inorganic pigments with these resins, high quality paper, medium quality paper, rolls Those manufactured from pulp fibers such as paper, recycled paper, and coated paper can be used. In order to improve the uniformity of the image, the support made of pulp fibers is preferably provided with a coating layer in advance and then with a heat-sensitive layer.

  As one of the forms of the multicolor thermal recording material, two thermal recording layers having different color development temperatures and different colors are laminated on one surface of the support, and the upper thermal recording layer is formed. A multicolor heat-sensitive recording material containing a developer / reversible developer in the layer and the developer of the present invention in the lower heat-sensitive recording layer can be mentioned. Among them, the developer / developer used in the upper heat-sensitive recording layer expresses a color developing function when heated at low temperature, and develops a color erasing function when heated at a high temperature. It is an amphoteric compound having a basic group that plays a role of color function. Typical acidic groups are phenolic hydroxyl groups or carboxyl groups, and basic groups are amino groups. The basic group may have as a functional group, but preferably has a basic group as a part of a salt compound such as a complex of a phenolcarboxylic acid compound and an amine compound.

  Specific examples of such a developer / subtractant include those shown below. Examples of the phenol carboxylic acid compound constituting the color reducing agent include 2-hydroxybenzoic acid, 3-hydroxybenzoic acid, 4-hydroxybenzoic acid, 3,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, 2,3 -Dihydroxybenzoic acid, 2,4-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid, 2,6-dihydroxybenzoic acid, gallic acid, bis (4-hydroxyphenyl) acetic acid, 3,3-bis (4-hydroxy) Phenyl) propionic acid and the like. Examples of amine compounds that form salts or complex salts with phenol carboxylic acid compounds include octylamine, nonylamine, decylamine, laurylamine, tetradecylamine, heptadecylamine, stearylamine, behenylamine, 3-methoxypropylamine, hexamethylenediamine, etc. Is mentioned.

  The reversible developer is, for example, a phenolic compound or phosphonic acid compound having an aliphatic hydrocarbon group having 8 or more carbon atoms. Specific examples of such a reversible developer include those shown below, as long as they exhibit a color developing function when heated at a low temperature and a color erasing function when heated at a high temperature. However, the present invention is not limited to this. 4- (octadecylthio) phenol, 4- (docosylthio) phenol, 4- (octadecyloxy) phenol, 4- (docosyloxy) phenol, N-octadecyl-4-hydroxybenzamide, 4'-hydroxydocosananilide, N- ( 4-hydroxyphenyl) -N′-n-octadecylurea, docosylphosphonic acid and the like. When recording with a thermal printer using a multicolor thermal recording material, only the low-temperature coloring layer is colored in low-temperature heating printing, and in the high-temperature heating printing, the low-temperature coloring layer in the printing area is decolored and only the high-temperature coloring layer is colored. To do.

  In addition, when the developer of the present invention is used in combination with another developer having a very high recording image storage stability, a recorded image having a sufficient color density and color development can be obtained as a markedly stable article for laser marking. This is particularly advantageous from the viewpoint of long-term storage. In the article for laser marking, it is preferable to contain a recording sensitivity improver in the thermosensitive recording layer. As the recording sensitivity improver that can be used, those having the ability to absorb laser light used for irradiation are used, and specific examples thereof include aluminum hydroxide, wollastonite, bentonite, mica (white mica, gold Mica), calcium silicate, talc, kaolin, clay and firelite, horn blend, various inorganic compounds such as silicate minerals such as part-time. Particularly preferred are aluminum hydroxide, white mica, wollastonite, and kaolin. These inorganic compounds can be used alone or in admixture of two or more.

  The use ratio of the fluoran compound of the present invention and the recording sensitivity improver in the thermosensitive recording layer can be appropriately selected according to the type of the fluoran compound of the present invention and the recording sensitivity improver used, and is not particularly limited. In general, however, the recording sensitivity improver can be used in the range of 10 to 5000 parts by weight, preferably 100 to 2000 parts by weight, with respect to 100 parts by weight of the color former. The ratio of the fluoran compound of the present invention, the developer, and the recording sensitivity improver in the heat-sensitive recording layer is 5-30 wt%, preferably 10-25 wt% of the fluoran compound of the present invention based on the total solid content in the layer. The developer can be within a range of 10 to 60 wt%, preferably 20 to 50 wt%, and the recording sensitivity improver can be within a range of 5 to 40 wt%, preferably 10 to 30 wt%.

In order to further improve the sensitivity of the article for laser marking, the above-described sensitizer can be similarly contained in the heat-sensitive recording layer.
The color marking agent is obtained by mixing the above-described colorless or light-colored fluoran compound of the present invention, a developer, a recording sensitivity improver, an aqueous binder and water, and further mixing various auxiliary agents as necessary. . As an auxiliary agent used here, for example, a dispersant such as sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate, a fatty acid metal salt, a concealing agent such as titanium oxide, an antifoaming agent, a viscosity Examples include regulators, fluorescent dyes, and colorants. The base material on which the coloring marking agent is printed (applied) is not particularly limited as long as it requires marking. For example, a predetermined portion such as a food container, a packaging material or an electronic component, or affixed to these parts. For example, an article such as a label base material. As the label substrate, paper such as paper and synthetic paper, synthetic resin film, plastics, metal-deposited paper and synthetic paper, metal-deposited film, metals, wood, etc. are appropriately used according to the application. The For example, the color marking agent may be prepared as follows. The binder is dissolved or dispersed in water or a solvent containing water as a main component. For color developing agents, color developers, recording sensitivity improvers, etc. that need to be dispersed in water or water-based solvents, use a dispersing machine such as a ball mill, an attritor, or a sand grinder, such as polyvinyl alcohol. The respective components are treated together or separately in water containing a dispersant or a water-containing solvent to form a dispersion. The average particle size after dispersion of each component is usually about 2 μm or less, preferably about 1 μm or less. Subsequently, a coloring marking agent is obtained by mixing a binder and a dispersion liquid. The solid content of the color marking agent is 20 to 70 wt%, preferably about 30 to 65 wt%.

  The coloring marking agent may be applied directly to the substrate, or may be applied to a substrate that has been subjected to surface treatment or undercoating in advance. Application | coating can be performed using suitable coating apparatuses, such as a roll coater, a gravure coater, a micro gravure coater, a knife coater, a spray coater, for example. The film thickness of the coating film (heat-sensitive recording layer) obtained after coating and drying can be generally 1 to 4 μm, and if it is thinner than 1 μm, the color developability by laser irradiation is inferior and the coating film is easily peeled off. On the other hand, if it is thicker than 4 μm, the drying property and labeling suitability tend to decrease. The drying varies depending on the coating conditions such as the line speed, and may be performed at room temperature, or may be performed by heating under conditions where the heat-sensitive recording layer does not develop color. The protective layer of the article for laser marking is provided by applying a transparent clear coat liquid on the heat-sensitive recording layer. This clear coat liquid is an aqueous composition composed of an aqueous binder, water and the like.

By irradiating the heat-sensitive recording layer on the marking article thus formed with a laser beam, the irradiated portion is heated, and the developer and the fluoran compound of the present invention act to cause color development and marking. The amount of energy of the laser to be irradiated is not particularly limited, but is preferably 1.4 J (joule) / cm ² or less in consideration of the possibility of destruction of the coating film. On the other hand, the lower limit of color development is unknown because there is no device that generates low energy, but sufficient color development is possible even with an energy of 0.4 J / cm ² . Therefore, the irradiation energy range for color development is suitably in the range of 0.4 to 1.4 J / cm ² , particularly 0.45 to 1.2 J / cm ² . Further, the laser to be irradiated is preferably a pulsed laser or a scanning laser, and the type of laser may be any of a gas laser, an excimer laser, and a semiconductor laser, specifically, carbon dioxide gas. Lasers, mixed gas lasers, YAG lasers, ruby lasers and the like can be mentioned.

  Labels as articles for laser marking are used for papers such as paper and synthetic paper, synthetic resin films, plastics, metal-deposited paper and synthetic paper, metal-deposited films, metals, etc. as substrates. Depending on the label substrate appropriately used, it can be produced by forming a heat-sensitive recording layer and a protective layer by the above-described method, and the use of the resulting label is directed to all the fields conventionally used. Particularly preferred are fields such as food, pharmaceuticals, toiletries, publications and electronic / electrical parts. Packaging materials for laser marking products include paper as a base material, paper such as synthetic paper, synthetic resin film, plastics, metal-deposited paper and synthetic paper, metal-deposited film, metals, glass A heat-sensitive recording layer and a protective layer are applied to various commonly used packaging materials such as boxes, wrapping paper, and packages using wood or the like as appropriate according to the application. The packaging material can be used for all fields that have been used in the past, but food, pharmaceuticals, toiletries, publications, and electronic / electrical parts are particularly preferable. The containers as the laser marking article of the present invention are made by using glass, plastic, and metals as a base material, and a thermal recording layer and a protective layer are provided on the base material by the method described above. The food container can be applied to all conventionally used fields such as bottles of alcoholic beverages and soft drinks, retort food containers, instant food containers, cosmetic containers, pharmaceutical containers, and toiletry products.

EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, a comparative example, and a reference example, the embodiment of this invention name is not restrict | limited to these examples. In the following description, parts represent parts by weight and% represents wt%.
First, analysis of each substance and performance evaluation methods handled in Examples, Comparative Examples, and Reference Examples will be described below.

<Measurement of phenol trinuclear content and composition ratio in developer>
It measured on the following conditions with the high performance liquid chromatograph (Hitachi High-Technologies Corporation make: L-7100).
Column: Cadenza CD-C18 (ODS column manufactured by Intact Corporation)
Developing solvent (vol ratio): Gradient treatment was performed with the following mixed solvent.
CH ₃ CN / H ₂ O (containing 0.15% ammonium acetate)
= 3/7 to 7/3 (40 minutes), or
7/3 to 9.6 / 0.4 (10 minutes)
・ Internal standard substance: Pyrene ・ Flow rate: 1 ml / min
・ Detector: UV254nm

<Melting point measurement>
Using a melting point measurement device (B-545, manufactured by Shibata Kagaku Co., Ltd.), the temperature was increased at a rate of 1 ° C./min, and the temperature at which the compound began to melt was visually determined as the melting point.
<Color test>
Using a predetermined thermal recording material, a thermal Okura Electric printing tester (TH-PMD) equipped with a Kyocera KJT-256-8MGF1 as a thermal head, an applied voltage of 24 V, a pulse width of 1.5 msec, and a printing energy of 0 The color was developed under the condition of .34 mj / dot and visually evaluated.

<High temperature and high humidity resistance test>
The colored recording material was allowed to stand in a constant temperature and humidity chamber at 45 ° C. and 95% RH for 24 hours, and the degree of fading from the color development before the standing was visually evaluated.
[Sensitivity evaluation]
The color density obtained by the color development test was visually evaluated according to the following criteria.
◎: Very good ○: Good ×: Poor [Evaluation of background fog]
The uncolored portion of the heat-sensitive recording material measured in the color development test was visually evaluated according to the following criteria.
◎: Very good ○: Good ×: Poor [Evaluation of resistance to high temperature and high humidity]
The colored portion after the high temperature and high humidity resistance test was visually evaluated on the basis of the following criteria.
◎: Very good ○: Good ×: Bad

[Example 1]
48.0 g (510 mmol) of phenol was added to the flask, and 5.0 g (25.6 mmol) of 2,6-dihydroxymethyl-4-tert-butylphenol was added to this, and dissolved by stirring. To this was added 0.074 g (0.73 mmol) of 36% hydrochloric acid with stirring at 30 ° C., and the mixture was stirred as it was for 5 minutes, and then reacted at 60 ° C. for 2 hours. The obtained reaction solution was washed with water to adjust the pH to 6, and then the excessively used phenol was removed under reduced pressure to obtain a condensation product as a developer of the present invention. The obtained developer has a phenol trinuclear (A) content of 86%, a residual phenol content of 0.6%, and the remainder derived from other condensation by-products. The content of the nucleus (C) was 12%, and the melting point was 126 ° C. Furthermore, by adding toluene to this developer, cooling and filtering after heating and stirring, the content of the phenol trinuclear (A) is 97% and the content of the phenol trinuclear (C) is 12%. A purified developer was obtained. The melting point of this purified developer was 130 ° C.

  Next, 2 g of the obtained developer was pulverized and dispersed in a paint shaker for 12 hours together with an aqueous solution of 2.5% polyvinyl alcohol (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name “Goselan L-3266”). Obtained. Further, 70 g of 3-dibutylamino-6-methyl-7-anilinofluorane as a fluorane compound was pulverized for 3 hours at a rotational speed of 2000 rpm with a sand grinder (Bessel capacity 400 ml, manufactured by Imex) together with 130 g of an 8% aqueous polyvinyl alcohol solution. Dispersion was obtained. Further, 70 g of β-naphthylbenzyl ether (trade name “BON”, manufactured by Ueno Pharmaceutical Co., Ltd.) as a sensitizer and a sand grinder (Bessel capacity: 400 ml, manufactured by Imex) together with 130 g of a 5.4% polyvinyl alcohol aqueous solution. A dispersion was obtained by grinding and dispersing at 2000 rpm for 3 hours. Further, 10 g of calcium carbonate was mixed with 30 g of water and stirred and dispersed with a stirrer to obtain a dispersion.

Next, 30 parts of the above developer dispersion liquid in its dry solid content, 15 parts of its 3-dibutylamino-6-methyl-7-anilinofluorane dispersion liquid in its dry solid content, and β-naphthylbenzyl ether dispersion liquid 30 parts by dry solid content, 20 parts by weight of calcium carbonate dispersion, 10 parts by weight of zinc stearate dispersion having a solid content of 16%, and 15% polyvinyl alcohol by 15 parts by weight. The coating liquid containing the color former composition of the present invention was obtained by stirring and mixing at a ratio of 7 parts by dry solid content.
This coating solution was applied to a base paper having a weight of 50 g / m ² with a bar coater with a rod number of 10. After drying, it was processed with a super calendar to obtain a heat-sensitive recording material. The coating amount of the coating liquid was 3 g / m ² by dry weight. Table 1 shows the performance evaluation results of the obtained heat-sensitive recording material.

[Example 2]
To the flask, 20 g of toluene and 48.0 g (510 mmol) of phenol as a phenolic compound were added, and 5.0 g (25.6 mmol) of 2,6-dihydroxymethyl-4-isopropylphenol was added as a p-substituted phenol derivative. The solution was stirred and dissolved. While stirring at 30 ° C., 0.12 (0.63 mmol) of p-toluenesulfonic acid monohydrate was added, and the mixture was stirred as it was for 5 minutes, and then reacted at 60 ° C. for 2 hours. The obtained reaction solution was washed with water to adjust the pH to 6, and then the solvent toluene and excess phenol were removed under reduced pressure to obtain a condensation product as a developer of the present invention. . The obtained developer has a phenol trinuclear (A) content of 90%, a residual phenol content of 0.4%, and the remainder derived from other condensation by-products. The content of the nucleus (C) was 16%, and the melting point was 130 ° C.
Using the obtained purified developer, a coating solution containing a color former composition and a performance evaluation test of a recording material were performed according to the method of Example 1. The results are shown in Table 1.

[Example 3]
Implementation was conducted except that 3- (N-ethyl-N-isoamylamino) -6-methyl-7-anilinofluorane was used as the fluorane compound instead of 3-dibutylamino-6-methyl-7-anilinofluorane. In accordance with the procedure of Example 1, a coating liquid containing a color former composition was prepared, and a performance evaluation test of a recording material was performed. The results are shown in Table 1.

[Example 4]
A mixture of 3-dibutylamino-6-methyl-7-anilinofluorane and 3- (N-ethyl-N-isoamylamino) -6-methyl-7-anilinofluorane as a fluorane compound in a weight ratio of 1: 1. According to the procedure of Example 1, the preparation of the coating liquid containing the color former composition and the performance evaluation test of the recording material were carried out except that was used. The results are shown in Table 1.

[Example 5]
A phenol trinuclear body (B) having an OH group at any of the 4- and 4'-positions of the right and left aromatic rings, obtained by condensing 2,6-dihydroxymethyl-4-methylphenol and phenol as a developer. Preparation of a coating solution containing a color former composition according to the method of Example 1 except that 1.6 g of BisP-PC (produced by Honshu Chemical Industry Co., Ltd., purity 98%, melting point 210 ° C.) was used. Then, a performance evaluation test of the recording material was performed. The results are shown in Table 1.

[Comparative Example 1]
According to the procedure of Example 1 except that 3-diethylamino-6-methyl-7-anilinofluorane is used as the fluorane compound instead of 3-dibutylamino-6-methyl-7-anilinofluorane. The coating liquid containing the agent composition was prepared and the performance evaluation test of the recording material was performed. The results are shown in Table 1.
The results in Table 1 show that the color former obtained by using the specific developer of the present invention and the specific fluorane compound can provide excellent performance in sensitivity, high temperature and high humidity resistance, and background fogging. . On the other hand, the comparative example is inferior to high temperature and high humidity resistance.

  The color developer using the specific developer and the specific fluorane compound of the present invention is useful as a heat-sensitive recording material excellent in moisture resistance under high temperature and high humidity, and has a great industrial utility value.

Claims (9)

A phenol trinuclear body (A) represented by the following general formula (1),
(A) having an OH group in at least one of the 4-, 4'-positions of the left and right aromatic rings;
(B) a developer containing a phenol trinuclear (B), wherein at least one of the adjacent substituents of at least one OH group substituted on the left and right aromatic rings is hydrogen;

(In the formula, _Ra is an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a halogen atom, an aralkyl group having 7 to 14 carbon atoms, and an aryl group. R _b is a group selected from the group consisting of hydrogen, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and a halogen atom, and R _b is a group selected from the group consisting of R _c may be the same as or different from each other, and R _c is hydrogen, halogen atom, cyano group, alkyl group having 1 to 18 carbon atoms, cycloalkyl group having 5 to 10 carbon atoms, alkoxy group having 1 to 4 carbon atoms, carbon number And a group selected from the group consisting of 7 to 14 aralkyl groups and aryl groups, R _c may be the same as or different from each other, and m and n represent an integer of 1 to 5.)
The following general formula (i)

(Here, Y1 and Y2 represent an alkyl group having 2 to 8 carbon atoms and an aralkyl group, and at least one of them has 4 to 8 carbon atoms.)
A color former containing a fluoran compound represented by the formula:   The color former according to claim 1, wherein the content of the phenol trinuclear body (A) and the phenol trinuclear body (C) not corresponding to the phenol trinuclear body (B) is 30 wt% or less.   3. The color former according to claim 1, wherein the ratio of the content of the phenol trinuclear body (B) to the content of the phenol trinuclear body (A) is 0.5 or more.   The color former according to any one of claims 1 to 3, wherein the content of the phenol trinuclear body (A) is 20 wt% or more. A condensation product obtained by condensing a p-substituted phenol derivative represented by the following general formula (2) and at least one of the phenolic compounds represented by the following general formula (3): The color former according to any one of claims 1 to 4, wherein the content of the condensation product component other than the phenol trinuclear body (A) contained in the condensation product is 50 wt% or less.

(In the formula, R _d is an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a halogen atom, an aralkyl group having 7 to 14 carbon atoms, and an aryl group. R _e is a group selected from the group consisting of hydrogen, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and a halogen atom, and R _e is the same as each other But it may be different.)

(In the formula, R _f is hydrogen, hydroxyl group, halogen atom, cyano group, alkyl group having 1 to 18 carbon atoms, cycloalkyl group having 5 to 10 carbon atoms, alkoxy group having 1 to 4 carbon atoms, or 7 to 14 carbon atoms. And R _f may be the same or different from each other.) R _{a in the} general formula (1) is an alkyl group having 2 to 18 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a halogen atom, an aralkyl group having 7 to 14 carbon atoms, and aryl. The color former according to any one of claims 1 to 5, wherein the color former is a group selected from the group consisting of groups, and _Rc is all hydrogen. The color former according to any one of claims 1 to 6, wherein _Rf in the general formula (3) is all hydrogen.   8. A recording material comprising the color developer according to claim 1 on a support.   The recording material according to claim 8, wherein the recording material is a heat-sensitive recording material.