JPH0784093B2 - Recording material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial field of application" The present invention develops a color by contacting with an electron-accepting substance such as an inorganic acid, an organic acid, a phenolic compound and their derivatives or an oxidizing agent, and produces a near red color. The present invention relates to a recording material containing a novel leuco compound having absorption in the outer region.

"Problems to be Solved by Conventional Techniques and Inventions" Various recording materials using leuco dyes such as pressure-sensitive recording materials and heat-sensitive recording materials have been known so far, and have become popular in computers in recent years. Due to its demand,
In the future, it tends to increase more and more.

The pressure-sensitive recording material generally consists of a sheet coated with pressure-sensitive burstable microcapsules containing a solution of a leuco dye in an organic solvent and a sheet coated with an electron-accepting substance. Sheets are stacked face to face and a recording image is obtained by applying writing pressure and impact pressure from above, and the heat-sensitive recording material is a mixture of a leuco dye and a color developer consisting of an electron-accepting substance. It is applied on a support sheet, and an image record is obtained by thermally applying an image signal thereto.

In the pressure-sensitive and heat-sensitive recording materials which are intended to obtain image recording based on the above principle, the main purpose has been to obtain a visible image.

Typical leuco dyes, such as phthalide compounds represented by crystal violet lactone and fluorane compounds having a substituted amino group, have a coloring structure that absorbs only in the visible region of 700 nm or less. However, recent optical character readers (OCR)
With the development and popularization of the above, special leuco dyes for pressure and heat recording have been required. That is, it is a leuco dye that gives a colored image having absorption in the near-infrared region, which has been demanded with the development of light sources.

Dyes / pigments having absorption in the near infrared region have been known for a long time, and are well known such as phthalocyanine, quinacridone, and chelate compounds of various metals, but since they also have large absorption in the visible region, It cannot be used as a dye for pressure-sensitive and heat-sensitive recording by a usual method.

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

Heretofore, some proposals have been made for leuco dyes having absorption in the near infrared wavelength region. For example, JP-A-51
-121035, JP 51-121037, JP 51-121038
Divinyl-containing phthalides disclosed in JP-A-51-167979, JP-A-60-226871 and JP-A-61-22076.
The spirofluorene phthalide and the like disclosed in the publication are considered to be dyes that can achieve the above-mentioned objects.

All of these conventional proposals are leuco dyes by imparting a phthalide structure to the dye structure, but the present invention is a leuco dye that is completely different from these known compounds, and that it is in contact with an electron accepting substance. The present invention provides a recording material containing a novel dye that develops color and has absorption in the near infrared wavelength region.

"Means and Actions for Solving Problems" The present invention is characterized by containing at least one tetraphenyl-1,4-pentadiene compound represented by the following general color [1] as a color former. It is a material.

[Wherein R ¹ , R ² , R ³ and R ⁴ are alkyl groups having 1 to 6 carbon atoms,
5- or 6-membered cycloalkyl group, arylalkyl group having 10 or less carbon atoms, hydrogen atom, or ethylene,
Represents an alkylene group selected from propylene and trimethylene, and in the case of alkylene, the other end which is not bonded to the nitrogen atom is bonded to the benzene nucleus carbon corresponding to the ortho position of the nitrogen atom, or the other end of R ¹ and R ² or R The other ends of ³ and R ⁴ join together to form a ring. Also, X ¹ and X ² are (R ⁵ and R ⁶ represent an alkyl group having 1 to ⁶ carbon atoms, a cycloalkyl group having 5 to 6 membered rings, an arylalkyl group having 10 or less carbon atoms, or an alkylene group selected from ethylene, propylene and trimethylene. In the case of alkylene, the other end which is not bonded to the nitrogen atom is bonded to the benzene nucleus carbon corresponding to the ortho position of the nitrogen atom, or the other ends of R ⁵ and R ⁶ are bonded to each other to form a ring. , R ^{5 at} X ¹
The R ⁶ in R ⁶ and X ² in R ⁵ or X ¹ in the X ^2,
It may be the same or different. ), Carbon number 1-6
Is an alkyl group, an alkoxy group having 1 to 6 carbon atoms, a group selected from hydrogen, chlorine and bromine, Y ¹ and Y ² are hydrogen and 1 to 1 carbon atoms.
It represents a group selected from an alkyl group having 6 or an alkoxy group having 1 to 6 carbon atoms. Hereinafter, the same symbols have the same meaning. The compound [1] of the present invention itself is usually colorless or pale and can be regarded as a so-called leuco dye.

This compound [1] slowly develops color by contacting it with an electron-accepting substance such as a phenol formalin-based resin, salicylic acid metal salts, bisphenols, attapulgite, clay minerals such as silton clay, and chloranil. It develops color rapidly upon contact with, and in each case forms a color image having a maximum absorption in the near infrared region of 700 nm to 900 nm.

Therefore, when the compound is used as a pressure-sensitive recording material or a heat-sensitive recording material, the characters and marks can be read by an optical character reader (OCR) using near infrared rays.

Any route may be adopted to obtain the compound [1] of the present invention, and for example, the following reaction route can be used.

The compounds [2] and [3] both belong to the 1,1-diphenylethylene derivative.

As a method for synthesizing the diphenylethylene derivative, a method utilizing a Grignard reaction is generally used.

[In the formula, A represents A ¹ and A ² , B represents B ¹ and B ² , and X represents chlorine, bromine, and iodine.] This reaction is a reaction of a Grignard reagent on a benzophenone derivative [4]. A high-yield and high-quality ethylene derivative can be easily obtained.

Also, although structurally limited, for example, an ethylene derivative of the following formula [5] 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 [4] obtained as described above into water or an alcohol solvent such as methanol, ethanol or propanol, or a lower alkyl-substituted ether of ethylene glycol or diethylene glycol, Alternatively, in a polar medium such as a cyclic ether such as tetrahydrofuran or dioxane, a mineral acid or a fatty acid such as formic acid or acetic acid, an organic sulfonic acid such as methanesulfonic acid or P-toluenesulfonic acid, or an acidic catalyst such as benzoic acid. It can be easily obtained by condensation with formaldehyde, trioxane or the like.

If the same kind is used as [2] and [3], [1]
As for [1], a symmetrical structure is obtained, and if different kinds are selected, an asymmetrical structure is obtained.

A known method can be used for producing a pressure-sensitive recording material using the compound of the formula [1].

For example, a method such as coacervation described in US Pat. Nos. 2,800,458 and 2,806,457 may be adopted.

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

In the production of these recording materials, it is of course possible to use the compound of the formula [1] alone, but it is possible to increase the usefulness as a recording material by co-use with the conventionally known color forming compounds. It is possible and can be mixed with various compounds depending on the purpose.

"Examples" Hereinafter, the present invention will be specifically described by showing examples of synthesis of the compound of the formula [1] and examples of recording materials using the compound.

Synthesis Example 1 53 g of 1,1-bis- (4-dimethylaminophenyl) ethylene, 26 g of 35% formalin aqueous solution, P-
Add 0.1 g of toluenesulfonic acid and react at 60 ° C for 20 hours.

After that, the precipitated crystals were filtered and recrystallized from toluene and ethyl acetate to obtain 13 g of 1,1,5,5-tetrakis- (4-dimethylaminophenyl) -1,4-pentadiene as pale yellowish sand crystals. obtain.

(Mp202.0 ° C to 205.5 ° C) It slowly developed a blue-green color on silica gel, and the reflection spectrum thereof showed λ _max 830 nm.

Elemental analysis Theoretical value Analytical value C 81.61 80.73 H 8.08 8.21 N 10.31 11.06 Synthesis example 2 1- (4-dimethylaminophenyl) -1- (4-methoxyphenyl) ethylene 12.7 in 75 cc of ethyl cellosolve
g, 6.4 g of 35% formalin aqueous solution and 0.5 g of P-toluenesulfonic acid are added, and the mixture is reacted at 80 ° C. for 24 hours.

After that, it was crystallized from toluene and ethyl acetate to give 1,5-bis-
5.3 g of cream crystals of (4-dimethylaminophenyl) -1,5-bis (4-methoxyphenyl) -1,4-pentadiene are obtained.

(Mp.178 ° C-183.5 ° C) This slowly developed a yellowish brown color on silica gel, and the reaction spectrum showed λ _max 800 nm.

Elemental analysis Theoretical value Analytical value C 81.08 81.13 H 7.33 7.48 N 5.40 5.22 Synthesis example 3 to synthesis example 12 Synthesis was performed in the same manner as Synthesis example 1, and is summarized in the following table.

Example 1 7 g of the compound obtained in Synthesis Example 1 was converted into monoisopropylbiphenyl.
Dissolve in 98g, 24g gelatin, arabic gum 24g in this solution
A solution prepared by dissolving g in 400 cc of water and adjusting the pH to 7 was added and emulsified with a homogenizer. To this emulsion, add 1000g of warm water and 50 ℃
After stirring for 30 minutes, add about 1 g of 10% caustic soda solution and add
The mixture was stirred at 50 ° C for 30 minutes. Then dilute acetic acid is gradually added to add PH.
The mixture was adjusted to 4.5, stirred at 50 ° C for about 1 hour, cooled to 0 ° C to 5 ° C, and further stirred for 30 minutes. Then, 85 g of 4% glutaraldehyde aqueous solution was gradually added to harden the capsule, and then the pH was adjusted to 6 with a dilute caustic soda aqueous solution and stirred at room temperature for several hours to complete encapsulation. There was no coloring phenomenon during this operation.

This capsule liquid was uniformly applied to paper with a wire bar and dried to obtain capsule-coated paper (top paper). When this paper was overlaid on a paper (lower leaf paper) coated with activated clay as a color developer and writing was performed with a ballpoint pen, a blue-green image slowly appeared on the lower leaf paper. The image showed excellent lightfastness and showed a maximum absorption at 830 nm when the reflection spectrum was measured.

Example 2 8 g of the compound obtained in Synthesis Example 7 was mixed and ground with 15 g of a 10% aqueous polyvinyl alcohol solution (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 dye after grinding was 3-5 microns.

On the other hand, 3.5 g of bisphenol A (15 g) in 10% polyvinyl alcohol solution and 6.5 g of water are similarly mixed and pulverized in a ball mill until the particle size becomes 3 to 5 microns to obtain "component B".

Next, 0.3 g of the component A and 6.7 g of the component B were mixed and dried, and then coated on a fine paper with a wire bar so as to have a solid content weight of 6 g / m ^2, and dried to obtain a thermosensitive recording paper. This heat-sensitive recording paper was pure white without fog, and was slowly colored by heating with a hot pen to give a black-purple image. This image showed excellent lightfastness and the measured reflectance spectrum showed an absorption maximum at 800 nm.

"Effect of the invention" The present invention uses a completely structurally novel tetraphenyl-1,4-pentadiene compound as a leuco dye, and develops a color image having absorption in the near infrared wavelength region by contact with an electron accepting substance. To provide a recording material for forming
It is expected to be used for R. etc.

Claims (1)

[Claims] 1. A recording material containing at least one tetraphenyl-1,4-pentadiene compound represented by the following general formula [1] as a color former. [Wherein R ¹ , R ² , R ³ and R ⁴ are alkyl groups having 1 to 6 carbon atoms,
5- or 6-membered cycloalkyl group, arylalkyl group having 10 or less carbon atoms, hydrogen atom, or ethylene,
Represents an alkylene group selected from propylene and trimethylene, and in the case of alkylene, the other end which is not bonded to the nitrogen atom is bonded to the benzene nucleus carbon corresponding to the ortho position of the nitrogen atom, or the other end of R ¹ and R ² or R ³ And the other end of R ⁴ join together to form a ring. Also, X ¹ and X ² are (R ⁵ and R ⁶ represent an alkyl group having 1 to ⁶ carbon atoms, a cycloalkyl group having 5 to 6 membered rings, an arylalkyl group having 10 or less carbon atoms, or an alkylene group selected from ethylene, propylene and trimethylene. In the case of alkylene, the other end which is not bonded to the nitrogen atom is bonded to the benzene nucleus carbon corresponding to the ortho position of the nitrogen atom, or the other ends of R ⁵ and R ⁶ are bonded to each other to form a ring. R ⁵ and X ^{2 at} X ¹
The R ⁶ in R ⁶ and X ² in R ⁵ or X ¹ in, may be the same or different. ), An alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, hydrogen, chlorine,
In the group selected from bromine, Y ¹ and Y ² each represent a group selected from hydrogen, an alkyl group having 1 to 6 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms. ]