JP2582572B2 - Recording material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial application field" The present invention provides a color development upon contact with an electron accepting substance such as an inorganic acid, an organic acid, a phenolic compound and their derivatives or an oxidizing agent, and a visible region, In some cases,
The present invention relates to a recording material containing a novel leuco dye having absorption in the near infrared region.

"Problems solved by the prior art and the invention" Various recording materials using leuco dyes, such as pressure-sensitive recording materials and heat-sensitive recording materials, have been known. With the spread, the demand tends to increase more in the future.

Generally, a pressure-sensitive recording material is composed of two sheets, a sheet coated with a pressure-sensitive rupturable microcapsule containing an organic solvent solution of a leuco dye and a sheet coated with an electron-accepting substance. A recording image is obtained by applying the writing pressure of a ballpoint pen or the like and the impact pressure of a typewriter or the like from the upper part with the sheets facing each other, and the thermosensitive recording material is more than the leuco dye and the electron accepting substance. This is mixed with a color developer and applied onto a support sheet, and an image is recorded by thermally applying an image signal to the support sheet or the like.

As described above, the main purpose of a pressure- and heat-sensitive recording material for obtaining a recorded image according to the principle is to obtain a visible image.

As leuco dyes that can be used in these applications, dyes having various structures such as phthalides represented by crystal violet lactone (CVL), fluorans having a substituted amino group, and spiropyrans have been proposed and put to practical use.

CVL is widely used as a representative colorant for obtaining a clear blue color, but because of the poor lightfastness of the color image, a colorant such as benzoyl leucomethylene blue (BLMB) is slow, but a colorant with good lightfastness of the color image It has been used together.

The dye provided by the present invention is a novel leuco dye which develops a bluish color, which is slow in color development like BLMB but excellent in light fastness of a color image. Although BLMB is excellent in light fastness of a color image, it tends to be gradually colored in a solution state, so when used for pressure-sensitive recording paper, the amount used has to be limited,
There was a need for the development of an alternative dye.

On the other hand, with the development of light sources such as semiconductor lasers in recent years, optical character reading devices (OCR) have been developed and spread, and O.R.
Leuco dyes that provide a color image having absorption not only in the visible region but also in the near-infrared region so that they can be read by CR and the like have been required.

Dyes and pigments having absorption in the near-infrared region are conventionally known, and are well-known, such as phthalocyanine, quinacridone, and other chelating compounds of metals. However, these have a large absorption in the visible region as well. However, it cannot be used as a dye for pressure- and heat-sensitive recording by a usual method.

In order to be used for such a purpose, it is necessary to have a so-called leuco structure, which is colorless or pale in color due to its characteristics, but can give a colored structure by contact with an electron accepting substance. .

Conventionally, several proposals have been made for leuco dyes having absorption in the near infrared region.

For example, JP-A-51-121035, JP-A-51-21037,
JP-A-51-121038, JP-A-51-167979, JP-A-58-118
Divinyl-containing phthalide disclosed in 157779,
Spirofluorene phthalide and the like disclosed in JP-A-60-226871 and JP-A-61-22076 are regarded as dyes capable of achieving the above-mentioned object.

These conventional proposals all provide a leuco dye by adding a phthalide structure to the dye structure. The present invention is a leuco dye that is completely different from these known compounds, and is usually colorless or pale in color, but develops color when it comes into contact with an electron accepting substance, and some of them are in the visible region only. Another object of the present invention is to provide a recording material containing a novel dye that has absorption in the near infrared region.

"Means and Actions for Solving the Problems" That is, the present invention is characterized by containing at least one kind of a tetraphenyl-1,4-pentadiene compound represented by the following general formula [1] as a coloring agent. It is a recording material.

[Wherein R ¹ , R ² , R ³ and R ⁴ represent an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having a 5 to 6 membered ring, an allylalkyl group having 10 or less carbon atoms, or ethylene, Represents an alkylene group selected from propylene and trimethylene;
In the case of an alkylene group, the other end which is not bonded to a nitrogen atom is bonded to a benzene nucleus carbon at the ortho position of the nitrogen atom, or R ¹
And attached at the other end comrades at the other comrades or R ³ and R ⁴ in R ^2, form a ring. X ¹ and X ² are (R ⁵ and R ^{6 each} represent an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having a 5 to 6 membered ring, an allyl alkyl group having 10 or less carbon atoms, or an alkylene group selected from ethylene, propylene and trimethylene In the case of an alkylene group, the other end which is not bonded to a nitrogen atom is bonded to a benzene nucleus carbon at the ortho position of the nitrogen atom, or is bonded to the other ends of R ⁵ and R ⁶ to form a ring.) A group selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, hydrogen, chlorine and bromine; Y ¹ and Y ² are hydrogen, an alkyl group having 1 to 6 carbon atoms and 1 carbon atom; And represents a group selected from the alkoxy groups of 1 to 6. Z represents a heterocyclic group containing one heteroatom selected from nitrogen, oxygen and sulfur. Hereinafter, the same symbols have the same meaning. The compound [1] of the present invention is itself colorless or pale and can be regarded as a so-called leuco dye.

This compound is a phenol-formalin resin,
Color develops by contacting with electron accepting substances such as salicylic acid metal salts, bisphenols, attapulgite, clay minerals such as Shilton clay, and also develops by contact with oxidizing agents such as chloranil. In the visible region of ~ 700nm, sometimes 700nm
A color image having absorption in the near infrared region of about 900 nm is formed. Therefore, if the compound is used as a pressure- and heat-sensitive recording material, the characters and marks can be read by an optical character reader (OCR).

Although any route may be adopted for obtaining the compound [1] of the present invention, it can be obtained, for example, by the following reaction route.

[Where, Means respectively. Compounds [2] and [3] both belong to 1,1-diphenylethylene derivatives, and as a synthesis method, a method utilizing a Grignard reaction is generally used.

(Wherein A represents A ¹ or A ² , B represents B ¹ or B ² ,
X represents C1, Br, I. This reaction causes a Grignard reagent to act on the benzophenone derivative [5], and it is very easy to obtain a high-yield and high-quality ethylene derivative.

Further, an ethylene derivative having the structure of the formula [6] Can also be obtained by the method disclosed in JP-A-61-93143.

The target compound [1] is obtained by converting the ethylene derivative [2], [3] or [6] obtained as described above to water or an alcoholic solvent such as methanol, ethanol or propanol, a lower alkyl-substituted ether of ethylene glycol or diethylene glycol, Alternatively, in a polar solvent such as a cyclic ether such as tetrahydrofuran or dioxane, a mineral acid such as hydrochloric acid or sulfuric acid, a fatty acid such as formic acid, acetic acid or propionic acid, an organic sulfonic acid such as methanesulfonic acid or P-toluenesulfonic acid, or It can be easily obtained by condensing with compound [4] in the presence of an acid catalyst such as a benzoic acid derivative.

If the same type is used as [2], [3] or [6], a symmetric structure is obtained as [1], and if different types are used, an asymmetric structure is obtained as [1].

In producing a pressure-sensitive recording material using the compound of the general formula [1], a known method can be used.
For example, a method such as coacervation described in U.S. Pat. Nos. 2,800,458 and 2,806,457 may be employed.

Further, in order to produce the heat-sensitive recording material, a known method described in, for example, Japanese Patent No. 45-14089 can be adopted.

In the production of these recording materials, it is naturally possible to use the compound of the general formula [1] alone, but the usefulness as a recording material is increased by co-use with a conventionally known coloring compound. It can be mixed with various compounds according to the purpose.

"Examples and the like" Hereinafter, examples of the synthesis of the compound of the general formula [1] will be shown,
The present invention will be specifically described with reference to examples of recording materials using the same compound.

Synthesis Example 1 53 g of 1,1-bis (4-dimethylaminophenyl) ethylene and 21 g of 9-methyl-3-carbazolylaldehyde were added to a mixed solution of 200 cc of tetrachloroethylene and 150 cc of acetic anhydride. React for hours.

The reaction mixture is discharged into water, neutralized with caustic soda, added with 100 cc of tetrachloroethylene, separated by stirring, and separated. The organic layer is decolorized by adding activated carbon and activated clay, and then concentrated to about half the volume.

After cooling, the precipitated crystals were filtered and recrystallized twice from butanol to give 1,1,5,5-tetrakis (4-dimethylaminophenyl) -3- (9-methyl-3-carbazolyl) -1. 15 g of pale yellow crystals of 4,4-pentadiene (structural formula [8]) are obtained.

(Mp 209 ° C.) It slowly developed a blue color on silica gel and the reflection spectrum showed λ _max 625 nm.

Synthesis Example 2 9-butyl-3-carbazolylaldehyde was used in place of 9-methyl-3-carbazolylaldehyde in Synthesis Example 1, and 1,1,5,5-tetrakis (4-
Light yellow crystals of dimethylaminophenyl) -3- (9-butyl-3-carbazolyl) -1,4-pentadiene (structural formula [9]) are obtained. (Mp188 ° C) It slowly developed a blue color on silica gel and the reflection spectra showed λ _max 635 nm and 825 nm.

SYNTHESIS EXAMPLE 3 The procedure of Synthesis Example 1 was repeated, except that 9-methyl-3-carbazolylaldehyde was replaced with isonicotinaldehyde, and 1,1,5,5-tetrakis (4-dimethylaminophenyl) -3- (4- Obtain pale yellow crystals of (pyridinyl) -1,4-pentadiene (Structural Formula [10]) (mp. 247.5)
° C).

It developed a green color on silica gel and the reflection spectra showed λ _max 650 nm and 830 nm.

Synthesis Examples 4 to 12 Compounds [1] synthesized in the same manner as in Synthesis Example 1 using diphenylethylene of various structures and heterocyclic aldehydes are summarized in the following table.

Example 1 7 g of the compound obtained in Synthesis Example 2 was dissolved in 98 g of monoisopropylbiphenyl, and 24 g of gelatin and gum arabic were added to this solution.
A solution prepared by dissolving 24 g in 400 cc of water and adjusting the pH to 7 was added, and emulsified with a homogenizer. Add 1,000 g of warm water to this emulsion and add
Stirred at 0 ° C. for 30 minutes. Then slowly add dilute acetic acid to
The mixture was adjusted to 4.5, stirred at 50 ° C for 1 hour, cooled to 0 ° to 5 ° C, and further stirred for 30 minutes. Next, 85 g of a 4% glutaraldehyde aqueous solution is gradually added to cure the capsule, and thereafter,
The pH was adjusted to 6 with a dilute aqueous sodium hydroxide solution, and the mixture was stirred at room temperature for several hours to complete the encapsulation. During this operation, there was no coloring phenomenon.

This capsule liquid was uniformly applied to paper with a wire bar and dried to obtain a capsule-coated paper (upper paper). This paper was used as a color developer and superimposed on paper (lower paper) coated with activated clay, and when writing with a ballpoint pen, a blue image slowly appeared on the lower paper. This image shows excellent light fastness, and shows a maximum absorption at 640 nm when the reflection spectrum is measured.
It also showed large absorption in the infrared region at 830 nm in the form of a shoulder.

Example 2 8 g of the compound obtained in Synthesis Example 3 was mixed and pulverized with 15 g of a 10% aqueous solution of polyvinyl alcohol (PVA-105 manufactured by Kuraray Co., Ltd.) and 6.5 g of water in a ball mill for 20 hours to obtain “Component A”. The particle size of the pigment after pulverization was 3 to 5 microns.

On the other hand, 3.5 g of bisphenol A, 15 g of a 10% aqueous solution of polyvinyl alcohol and 6.5 g of water were similarly mixed and pulverized by a ball mill until the particle diameter became 3 to 5 μm.
And

Next, 0.3 g of component A and 6.7 g of component B were mixed, dried, applied to a high quality paper with a wire bar so as to have a solid weight of 6 g / m ^2, and dried to obtain a thermosensitive recording paper. This thermal recording paper
It was creamy with no fog and developed color when heated with a hot pen or the like to give a blue-green image. This image shows excellent lightfastness and the reflection spectrum shows a maximum absorption at 650 nm.
It also showed large shoulder-like absorption in the infrared region from 00 to 830 nm.

[Effects of the Invention] The present invention provides a recording material that uses a structurally completely new tetraphenyl-1,4-pentadiene compound as a leuco dye and can be substituted for a conventional color recording material using benzoylleucomethylene blue. Is made possible.

Claims (1)

(57) [Claims] 1. A recording material comprising at least one tetraphenyl-1,4-pentadiene compound represented by the following general formula [1] as a coloring agent. [Wherein R ¹ , R ² , R ³ and R ⁴ represent an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having a 5 to 6 membered ring, an allylalkyl group having 10 or less carbon atoms, or ethylene, Represents an alkylene group selected from propylene and trimethylene;
In the case of an alkylene group, the other end which is not bonded to a nitrogen atom is bonded to a benzene nucleus carbon at the ortho position of the nitrogen atom, or R ¹
And attached at the other end comrades at the other comrades or R ³ and R ⁴ in R ^2, form a ring. X ¹ and X ² are (R ⁵ and R ^{6 each} represent an alkyl group having 1 to ⁶ carbon atoms, a cycloalkyl group having a 5 to 6 membered ring, an allyl alkyl group having 10 or less carbon atoms, or an alkylene group selected from ethylene, propylene and trimethylene. represents, and the other end which does not bind when the nitrogen atom of the alkylene group can be bound to the benzene ring carbon hitting the ortho position of the nitrogen atom, attached at the other end comrade R ⁵ and R ⁶ form a ring.) An alkyl group having 1 to 6 carbon atoms,
Y ¹ and Y ^{2 each} represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a group selected from an alkoxy group having 1 to 6 carbon atoms; Express. Z represents a heterocyclic group containing one heteroatom selected from nitrogen, oxygen and sulfur. ]