JPH04244086A - Crystalline solvate of fluoran compound, its production and recording material containing the same crystalline solvate - Google Patents

Abstract

PURPOSE:To obtain a new solvate useful as a coloring compound used as a recording material such as a pressure-sensitive recording or a heat-sensitive recording material. CONSTITUTION:A crystalline solvate of a fluoran compound composed of the fluoran compound expressed by the formula (R1 and R2 are cyclohexyl, n-butyl or isobutyl, except groups of both the same R1 and R2) and benzene or xylene. Furthermore, the aforementioned solvate is obtained by dissolving the compound expressed by the formula in an organic solvent containing >=50wt.% benzene or xylene and depositing the above-mentioned compound as crystals from the resultant solution.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to fluoran compounds useful as color-forming compounds used in recording materials such as pressure-sensitive recording materials and heat-sensitive recording materials, and more specifically to crystalline solvates of fluoran compounds, The present invention relates to a method for producing a crystalline solvate and a recording material containing the crystalline solvate.

0002

[Prior Art] Conventionally, a color reaction between a colorless or light-colored electron-donating compound (color-forming compound) and an organic or inorganic electron-accepting substance (color developer) is used. Methods for recording information transmitted through the medium of external energy include pressure-sensitive recording, heat-sensitive recording, and energized heat-sensitive recording. In these recording systems, fluoran compounds are widely used as color-forming compounds. Various new or modified compounds have been proposed as such fluoran compounds. However, materials having characteristics suitable for use in various recording materials have been developed.

[Problem to be solved by the invention]

The object of the present invention is to further improve the applicability of novel fluoran compounds to recording materials, and in particular, to improve the dissolution rate in capsule oil when applied as pressure-sensitive recording materials. It is an object of the present invention to provide a fluoran compound that has the following properties.

[Means to solve the problem]

The present inventors investigated new fluoran compounds as color-forming compounds for recording materials, and obtained the general formula (1).

[Formula 2] (wherein R1 and R2 are cyclohexyl groups, n-
It was discovered that a fluoran compound represented by a butyl group or an isobutyl group (except when R1 and R2 are both the same group) is an extremely excellent color-forming compound, and the patent application was filed earlier. Ganpei 2-18532
No. 7). The fluoran compound represented by the general formula (1) has very good solubility in capsule oil for use in pressure-sensitive recording materials, for example, and has excellent applicability as a coloring compound for recording materials. The present inventors have proposed this general formula (1
) Regarding the fluoran compound represented by formula (1), we further investigated the applicability of the compound as a recording material. They found that this crystalline solvate has a greatly improved dissolution rate in capsule oil, and completed the present invention.

That is, the present invention provides general formula (1)

[C3
] (wherein R1 and R2 are cyclohexyl group, n-
A crystalline solvate of a fluoran compound consisting of a fluoran compound represented by a butyl group or an isobutyl group (except when R1 and R2 are both the same group) and an organic solvent of benzene or xylene. In addition, this crystalline solvate can be prepared by combining the fluoran compound represented by the general formula (1) with benzene or xylene alone, or by using benzene or xylene as a single solvent.
This is a method for producing a crystalline solvate characterized by precipitating it as crystals from an organic solvent containing 0% by weight or more. Furthermore, it is a recording material characterized by containing the crystalline solvate.

The crystalline solvate of the fluoran compound represented by the general formula (1) of the present invention is characterized in that it is composed of the fluoran compound represented by the general formula (1) and benzene or xylene. . For example, in the general formula (1), a fluoran compound in which R1 is a cyclohexyl group and R2 is an n-butyl group forms a particularly preferred crystalline solvate with benzene, o-xylene or m-xylene. Furthermore, in the general formula (1), a fluoran compound in which R1 is an isobutyl group and R2 is an n-butyl group forms a particularly preferable crystalline solvate with o-xylene, m-xylene, or p-xylene. .

In order to produce a crystalline solvate of the fluoran compound represented by the general formula (1) of the present invention and benzene or xylene, the fluoran compound represented by the general formula (1) The compound can be produced by precipitating the compound as crystals from a single solvent of benzene or xylene, or from an organic solvent containing 50% by weight or more of benzene or xylene. For example, to produce a crystalline solvate with xylene, a fluoran compound represented by general formula (1) is dissolved in xylene as an organic solvent or an organic solvent containing 50% by weight or more of xylene, and in this solvent, Precipitate as crystals.

In the above method, benzene or xylene constituting the solvate with the fluoran compound represented by general formula (1) is preferably used as a sole solvent, but benzene or xylene is used in an amount of 50% by weight or more. It may be used as a mixed organic solvent with other organic solvents contained therein. In this case, examples of organic solvents other than benzene or xylene include alcohols such as methanol, isopropanol, and n-butanol, ketones such as acetone and ethyl ethyl ketone, esters such as ethyl acetate, dioxane, and tetrahydrofuran. Examples include ethers. In such mixed organic solvents, the content of benzene or xylene is 50% by weight.
If it is less than that, unsolvated crystals may precipitate together with the desired crystalline solvate, which is not preferable. In order to efficiently precipitate the crystalline solvate, the content of benzene or xylene in the mixed organic solvent is 50% by weight or more, more preferably 80% by weight or more. More preferably benzene or xylene is used alone.

The amount of organic solvent used in the production of the crystalline solvate is at least 0.4 times the weight of the fluoran compound represented by general formula (1). Although it is not a particular problem to use a large amount of an organic solvent, it is practically undesirable because it may require operations such as concentration to precipitate crystals. The amount of organic solvent used is usually 0.4 to fluoran compound represented by general formula (1).
~100 times the weight, preferably 0.5 ~50
It is twice the weight. In order to precipitate a crystalline solvate as crystals, a method is often used in which a fluoran compound is once completely dissolved in an organic solvent, and then cooled and precipitated. At this time, if necessary, heating may be performed in a range of room temperature or higher and the boiling point of the organic solvent in order to completely dissolve the fluoran compound. After complete dissolution, crystals are precipitated by stirring or standing still. The precipitated crystals can be subjected to a known method, for example, by filtration and then drying, to obtain the desired crystalline solvate of the fluoran compound.

The melting point of the benzene- or xylene-solvated crystalline solvate of the fluoran compound of the present invention produced as described above is expressed by the unsolvated general formula (1
) is shown in Table 1 along with the melting point of the crystal of the fluoran compound.

[Table 1]

[0011] Moreover, these crystalline solvates Cu-K
Powder X-ray diffraction patterns measured using α-rays are shown in FIGS. 1 to 6. As is clear from these powder X-ray diffractograms, the crystalline solvate of the fluoran compound of the present invention is a crystal with unique peaks. For example, in general formula (1),
A crystalline solvate (hereinafter referred to as crystalline solvate A-1) composed of a fluoran compound in which R1 is a cyclohexyl group and R2 is an n-butyl group and benzene is a powder X shown in FIG. In a line diffraction diagram, the diffraction angle (2
θ) shows a strong peak at 6.3° and a relatively strong peak at 20.1°. Similarly, in general formula (1),
A crystalline solvate (hereinafter referred to as crystalline solvate A-2) composed of a fluoran compound in which R1 is a cyclohexyl group and R2 is an n-butyl group and o-xylene is shown in FIG. In a powder X-ray diffraction diagram, the diffraction angle (
2θ) strong peak at 5.5°, 17.7° and 18.
A crystalline solvate (hereinafter referred to as In the powder X-ray diffraction diagram shown in FIG.
A relatively strong peak is shown at 8.6°. Furthermore, R1
A crystalline solvate (hereinafter referred to as crystalline solvate B-1) composed of a fluoran compound in which is an isobutyl group and R2 is an n-butyl group and o-xylene is a powder shown in FIG. In the X-ray diffraction diagram, the diffraction angle (2θ)5.
It shows a strong peak at 7° and a relatively strong peak at 21.7°. Similarly, in general formula (1), a crystalline solvate (
In the powder X-ray diffraction diagram shown in FIG. It shows a relatively strong peak at .3°, and in general formula (1), R1
A crystalline solvate (hereinafter referred to as crystalline solvate B-3) composed of a fluoran compound in which is an isobutyl group and R2 is an n-butyl group and p-xylene is a powder shown in FIG. In the X-ray diffraction diagram, the diffraction angle (2θ)5.
It shows a strong peak at 6°. The powder X-ray diffraction diagram of each crystalline solvate was measured by the X-ray diffraction method using Cu-Kα rays, and each diffraction (2θ) display is ±0.
．． An error of about 2° is acceptable.

[0012] The crystalline solvate of the fluoran compound of the present invention interacts with benzene or xylene in some way when the fluoran compound represented by the general formula (1) crystallizes, so that benzene is formed in the crystal lattice. Alternatively, it is thought that it is a crystal that incorporates xylene. For example, when measuring the 1H-NMR spectrum of crystalline solvate (A-1) in DMSO-d6, in general formula (1), R1
A peak derived from a fluoran compound in which R is a cyclohexyl group and R2 is an n-butyl group and a peak derived from benzene are observed, indicating that the crystalline solvate dissociates into fluoran molecules and benzene molecules in a solution state. You can see that The crystalline solvate of the fluoran compound represented by the general formula (1) of the present invention and benzene or xylene can be treated as stable crystals below their respective melting points. On the other hand, when the crystalline solvate is heated in, for example, isopropanol, n-butanol, or acetonitrile, it easily converts into crystals of the fluoran compound represented by the general formula (1) that is not solvated with benzene or xylene. It can be converted to .

As shown in Table 1, the crystalline solvate of the present invention has a lower melting point than the unsolvated compound, and as shown in Table 2 below, the crystalline solvate of the present invention has a faster dissolution rate in capsule oil and has color-forming properties. As a compound, its applicability to various recording materials has expanded. In the recording material containing the crystalline solvate of the present invention, the crystalline solvate of the fluoran compound represented by the general formula (1) may be used alone or in combination, and further, for example, the hue of the color, etc. Other color-forming compounds such as triphenylmethane lactones,
Color-forming compounds such as fluorans and spiropyrans may be mixed and used as desired. That is, the pressure-sensitive recording material containing the crystalline solvate of the present invention can be prepared using a solvent commonly used in this field, such as an alkylbenzene type (n-dodecylbenzene etc.), an alkyl biphenyl type (triethyl biphenyl, diisopropylbiphenyl etc.). etc.), hydrogenated terphenyls, alkylnaphthalenes (diisopropylnaphthalene, etc.), diarylethanes (phenylxylylethane, styrenated ethylbenzene, etc.)
, or dissolved in a single or mixed solvent of various chlorinated paraffinic solvents, and the solution is mixed with gelatin, melamine-aldehyde, or urea-aldehyde resin, polyurethane, polyurea by a method such as a coacervation method or an interfacial polymerization method. The aqueous dispersion of the resulting capsules is encapsulated in microcapsules having partition walls made of polyamide or the like, and the resulting aqueous dispersion is placed on a suitable support (e.g., paper, plastic sheet, etc.) together with a suitable binder (e.g., starch glue, latex, etc.). , resin-coated paper, etc.) and used as a pressure-sensitive recording sheet. Of course, it is also possible to use a so-called intermediate sheet in which one side of the support is coated with the above capsule dispersion liquid and the other side is coated with a color developer coating liquid mainly consisting of a color developer. Apply a coating liquid containing a mixture of capsules and color developer, or
The capsules and the color developer are made to coexist on the same surface by applying a color developer coating liquid on top of the capsule dispersion,
It can also be used for so-called stand-alone copy sheets. In this case, as the color developer, a large number of copolymers of salicylic acid, phenols, and aldehydes (for example, formaldehyde resin), substituted salicylic acids (alkyl-substituted, aryl-substituted, or aralkyl-substituted products) are known; for example, 3, 5-di-alpha-methylbenzylsalicylic acid), cocondensation resins of substituted salicylic acids and styrene, alkylphenols (e.g. octylphenol), phenol-aldehyde resins (e.g. novolac resins of p-phenylphenol) or metals thereof. salts (e.g. zinc, magnesium, aluminum, calcium,
(metal salts such as tin, nickel, etc.) and activated clays.

When used in a heat-sensitive recording material, the crystalline solvate of the present invention and a color developer (for example, bisphenol A or its halide or alkylated product, dihydroxydiphenyl sulfone or its halide or alkylated product, hydroxybenzoic acid ester) phenols such as hydroquinone monoethers, salicylic acid derivatives, salicylic acid amide derivatives, urea derivatives,
A binder (for example, polyvinyl alcohol or Modified products thereof, methylcellulose, hydroxyethylcellulose, carboxymethylcellulose, gum arabic, salts of styrene-maleic anhydride copolymers, isobutylene-acrylic acid-maleic anhydride copolymers, etc.), pigments (talc, kaolin, calcium carbonate, etc.) etc.), and, if necessary, sensitizers (higher fatty acid amides, aromatic carboxylic acids, or sulfonic acid esters, aromatic or aromatic group-substituted aliphatic ethers, or aromatic or aromatic group-substituted aliphatic ethers). Aliphatic hydrocarbons (generally known sensitizers for heat-sensitive recording materials) and other additives (for example, ultraviolet absorbers, antifoaming agents, etc.) are added,
It can be used as a heat-sensitive recording material by forming a fine dispersion and coating it on a suitable support (for example, paper, plastic sheet, resin-coated paper, etc.). Of course, it can also be used in a system using a solvent instead of an aqueous dispersion system without any problem. Moreover, it can also be used for applications using other color-forming compounds (for example, temperature-indicating materials).

[Effect]

The crystalline solvate of the present invention has high solubility in capsule oil, which is an important property required of a color-forming compound for pressure-sensitive recording materials, and has a very fast dissolution rate. Table 2 shows the results of comparing the dissolution rates in capsule oil of the crystalline solvate of the present invention and the unsolvated crystals represented by general formula (1). The dissolution rate was measured by using SAS-296 (manufactured by Nippon Petrochemicals) as the capsule oil and measuring the time taken for each compound to dissolve 10% by weight in the capsule oil at 80°C. From Table 2, it is clear that the crystalline solvate of the present invention has a dissolution rate in capsule oil that is more than twice as fast as the unsolvated crystal.

[Table 2]

【Example】

[0016] The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to these Examples.

[Example 1] General structural formula of crystalline solvate (A-1) (
In 1), R1 is a cyclohexyl group and R2 is n
-butyl group fluoran compound 30g to 40m
1 of benzene by heating under reflux. Cool to room temperature, filter the precipitated crystals, wash with n-hexane, and cool at 40°C.
Drying was performed to obtain 25 g of crystals. Melting point 130~
The powder X-ray diffraction pattern at 135° C. is shown in FIG.

[Example 2] Production Example 1 of crystalline solvate (A-2)
23 g of crystals were obtained by the method described in Example 1 except that o-xylene was used instead of benzene. Melting point: 135-140°C, powder X-ray diffraction pattern is shown in FIG.

[Example 3] Production Example 1 of crystalline solvate (A-3)
22 g of crystals were obtained by the method described in Example 1 except that m-xylene was used instead of benzene. The melting point was 125-128°C, and the powder X-ray diffraction pattern is shown in FIG.

[Example 4] Production of crystalline solvate (B-1) General formula (
In 1), 30 g of a fluoran compound in which R1 is an isobutyl group and R2 is an n-butyl group was heated to reflux and dissolved in 40 ml of o-xylene. Cool to room temperature, filter the precipitated crystals, wash with n-hexane, and cool at 40°C.
24 g of crystals were obtained. Melting point 107-11
The powder X-ray diffraction pattern at 1°C is shown in FIG.

[Example 5] Production Example 4 of crystalline solvate (B-2)
24 g of crystals were obtained by the method described in Example 4 except that m-xylene was used instead of o-xylene. The melting point was 115-118° C., and the powder X-ray diffraction pattern is shown in FIG.

[Example 6] Production Example 4 of crystalline solvate (B-3)
25 g of crystals were obtained by the method described in Example 5 except that p-xylene was used instead of o-xylene. The melting point was 115-120° C., and the powder X-ray diffraction pattern is shown in FIG.

[0017]

[Example 7] Creation of thermal recording paper using crystalline solvate (A-1) 10 g of crystals of crystalline solvate (A-1), 5 g of 10% polyvinyl alcohol aqueous solution and 37.5 g of water were The mixture was pulverized with a sand mill to a particle size of 3 μm. On the other hand, bisphenol A was similarly dispersed to obtain a 38% developer dispersion. 65.8 g of this color developer dispersion, 50 g of the above crystal aqueous dispersion, and 18.3 g of 60% light calcium carbonate aqueous dispersion.
, 88 g of 10% polyvinyl alcohol aqueous solution and 51.9 g of water were mixed. This mixed solution was applied to white base paper using wire rod No. No. 10 was used, and after coating, air drying was performed at room temperature to obtain thermosensitive recording paper. When heated, this thermosensitive recording paper very quickly developed a slightly reddish black color.

[Examples 8 to 12] In Example 7, crystalline solvate (
Crystalline solvates (A-2), (A-3) instead of A-1)
), (B-1), (B-2) and (B-3) were used, respectively, and heat-sensitive recording paper was prepared by the method described in Example 7. Upon heating, each thermal recording paper very quickly developed a slightly reddish black color.

[0018]

Example 13 Preparation of pressure-sensitive recording paper using crystalline solvate (A-1) Top (CB) paper and bottom (CF) paper were manufactured as follows. That is, 100 g of a 10% aqueous solution of ethylene-maleic anhydride copolymer and 240 g of water were mixed, the pH was adjusted to 4.0 with a 10% aqueous sodium hydroxide solution, and 5 weight of crystals of the crystalline solvate (A-1) were mixed. % dissolved phenylxylylethane (Japan Petrochemical Co., Ltd. SAS-
296) After mixing 200 g and emulsifying with a homomixer, 60 g of a 50% solids methylolmelamine aqueous solution (Eulamine T-30 manufactured by Mitsui Toatsu Chemical Co., Ltd.) was added, and the mixture was kept at 55°C for 3 hours while stirring, and the average A microcapsule dispersion having a particle size of 5.0 μm was obtained. To 100 g of this microcapsule dispersion, 4.0 g of wheat starch granules, 20 g of 20% oxidized starch paste, and 116 g of water were added and dispersed, and the coating amount was 5 g/m2 in terms of solid content on paper with a basis weight of 40 g/m2. CB paper was obtained. On the other hand, CF paper uses a zinc salt of a co-condensed resin of substituted salicylic acid and styrene as a color developer, and is made fine by a sand grinding mill in water in the presence of a small amount of polymeric anionic surfactant. A % by weight aqueous dispersion was obtained. Using this aqueous dispersion, make a water-based paint (solid content 30%) with the following composition, weighing 4
0 g/m2 high-quality paper was coated with a dry coating amount of 5.5 g/m2 to prepare CF paper. When the microcapsule-coated surface of the CB paper and the developer-coated surface of the CF paper were overlapped so as to face each other, and writing and pressure were applied, a red and black colored image was obtained on the developer-coated surface. The light fastness, moisture fastness and NOX resistance of this colored image had no practical problems.

[Examples 14 to 18] In Example 13, crystalline solvate (A-2), (
A-3), (B-1), (B-2) and (B-3) were respectively used, and CB paper and CF paper were prepared by the method described in Example 13, and the same procedure was used. A colored image was obtained. Light fastness, moisture fastness and NO resistance of each color image
X There was no problem in practical use.

[0019]

[Effect of the invention] The crystalline solvate of the present invention can be used as a recording material,
Particularly when used as a color-forming compound for pressure-sensitive recording materials, it has a high dissolution rate in capsule oil and is a useful color-forming compound for industrial use.

[0020]

[Brief explanation of the drawing]

FIG. 1 shows a powder X-ray diffraction pattern of crystalline solvate (A-1).

FIG. 2 shows a powder X-ray diffraction pattern of crystalline solvate (A-2).

FIG. 3 shows a powder X-ray diffraction pattern of crystalline solvate (A-3).

FIG. 4 shows a powder X-ray diffraction pattern of crystalline solvate (B-1).

FIG. 5 shows a powder X-ray diffraction pattern of crystalline solvate (B-2).

FIG. 6 shows a powder X-ray diffraction pattern of crystalline solvate (B-3). In each drawing, the horizontal axis represents the diffraction angle (2θ), and the vertical axis represents the diffraction intensity.

Claims (4)

[Claims] Claim 1 General formula (1) [Formula 1] (wherein R1 and R2 are cyclohexyl groups, n-
A crystalline solvate of a fluoran compound consisting of a fluoran compound represented by a butyl group or an isobutyl group (except when R1 and R2 are both the same group) and benzene or xylene. 2. Crystals of the fluoran compound according to claim 1, characterized in that the fluoran compound represented by the general formula (1) according to claim 1 is dissolved in benzene or xylene and precipitated as crystals from the solution. Method for producing a sexual solvate. 3. The fluoran compound represented by the general formula (1) according to claim 1 is dissolved in an organic solvent containing 50% by weight or more of benzene or xylene, and is precipitated as crystals from the solution. A method for producing a crystalline solvate of a fluoran compound according to claim 1. 4. A recording material comprising the crystalline solvate according to claim 1.