JPS5887089A - Heat-sensitive recording paper - Google Patents

Abstract

PURPOSE:To obtain a heat-sensitive recording paper having an improvided chromogenic property and an improved preventiveness to the color disappearance of recorded pictures by using a hindered phenolic compound, a colorless electron donative dye, and a p-hydroxy bezoate. CONSTITUTION:A colorless electron donative dye (A) (e.g., 3-diethylamino-6- chloro-7-anilinofluoran, etc.), a p-hydroxy benzoate (B)[e.g., preferably a compound of the formula (R is a C2-C8 alkyl or benzyl)], and a hindered phenolic compound (C)[e.g., preferably a phenol whose 2- or 6-position is substituted with t-butyl group (e.g., 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)]are separately dispersed by means of a ball mill, etc. These three dispersions are mixed together, further mixed with an oil-absorptive pigment (e.g., calcium carbonate, etc.), and then coated on a base paper to obtain objective recording paper.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-sensitive recording paper, and particularly to a heat-sensitive recording paper that has improved color development and prevents the recorded image from decoloring. Thermosensitive recording paper is a paper that obtains images by utilizing physical and chemical changes in substances caused by thermal energy, and a large number of processes are being studied.

Recently, thermosensitive recording paper has come to be used as output for facsimile/mm, computer output, and recording paper, taking advantage of its features such as primary color development and no need for a developing process. These are called the dye-7 type, in which a nearly colorless electron-donating dye is used as the electron-donating compound and phenols or other acidic substances are used as the electron-accepting compound.

No., Tokuko Akari! -/μ03 No., JP-A-Shojj-λ72j
It is disclosed in No. 3, etc.

In general, when thermosensitive recording paper is used as recording paper, it has the advantage that recording apparatuses can be made lighter and smaller, and its use has been rapidly increasing in recent years.

Performance that such thermal recording paper should have is (1) high 1l
(2) The obtained recorded image does not fade under the influence of external conditions such as humidity and heat. This can be mentioned.

These performances largely depend on the type of electron-accepting compound. Specific examples of electron-accepting compounds include phenolic compounds, organic acids or their feral salts, and hydroquine benzoate.

Among these electron-accepting compounds, p-hydroxybenzoic acid ester is superior in that a recorded image of the learned concentration can be obtained. However, although heat-sensitive IIE recording paper containing a combination of electron-donating dye and Nisdel p-hydroxybenzoate can produce recorded images with a high density, it has the disadvantage that the recorded images are very easily discolored. An object of the present invention is to provide a heat-sensitive recording paper that allows recording images of high density and that does not discolor under the influence of external conditions such as humidity and heat.

The objects of the present invention described above are (a) colorless electron-donating dyes, (b) p-hydroxybenzoic acid esters, and (c)
This was achieved with a heat-sensitive recording paper characterized by containing a hindered phenol compound.

Among the p-hydroxybenzoic acid esters used in the present invention, compounds represented by the following general formula (I) are preferred.

(In the formula, R represents an alkyl group with a carbon number λ ~ i x benzyl group) Specific examples of the p-hydroxybenzoate represented by the general formula (1) include ethyl p-hydroxybenzoate, p
-n-propyl hydroxybenzoate, l5O-propyl p-hydroxybenzoate, n-propyl p-hydroxybenzoate
Butyl, 1so-butyl p-hydroxybenzoate, p-
Examples include n-heptyl hydroxybenzoate and benzyl p-hydroxybenzoate. Two or more of these p-hydroxybenzoic acid esters can also be used in combination.

Among the hindered phenol compounds used in the present invention, preferred are phenols or derivatives thereof in which at least 7 or more of the λ or 4-positions are substituted with alkyl groups. Among them, 7 or more of the 2nd or 4th place are te
Phenols or derivatives thereof substituted with rt-butyl groups are preferred. Moreover, those having a plurality of phenol groups in the molecule are preferable, and those having 1 to 3 phenol groups are particularly preferable. Specific examples of these compounds include /, /, 3-) lis(2-methyl-≠-hydroxy-j
-tert-butylphenyl)butane44.4'/-thiobis(3-methyl-x -tert
-butylphenol), t,v'-thiobis(2-methyl-1,-tert-butylphenol), 4.2'-thiobis(μmmethyl-1,-tert-butylphenol)1. 2. ．． 2/-methylenebis(l-methyl-6-ter
t-butylphenol) 1. 2. j'-methylenebis(≠-ethyl-tert
-butylphenol), ≠'-butylidenebis(3-methyl-6-tert
-butylphenol), +,+'-methyL/7bis(,2,A-di-tert-butylphenol) is al.

Preferred among these are /, /, 3-tris(cortacyl-l-hydroxy-1
-tert-butylphenyl)methane, ! +4! '-thiobis(3-methy/l/-6-t
erl-butylphenol).

The amount of these hindered phenol compounds to be used is approximately 1 λOO weight percent, preferably λθ~10
Typical examples of electron-donating dyes used for 00 to 100 heavy needle percent light include (1) triarylmethane-based, (2) diphenylmethane-based, (3) xanthine-based, (
4) thiazine compounds, (5) spiropyran compounds, etc. Specific examples include JP-A-31-27153.
Examples include those listed in the No.

Among these, Sakaki xanthine-based color formers are preferred because they cause less fog and provide a brighter color density.

When producing materials for thermal recording paper, it is necessary to disperse the materials for thermal recording paper as described above using water as a dispersion medium6. Preferably, polymers are used.

A method for dispersing materials for heat-sensitive recording materials using these dispersion media generally involves dispersing water-soluble control molecules in an amount of 7% to 70% by weight, more preferably 2% to 1% by weight. Electron-donating dye or
p-hydroxybenzoic acid ester or hindered phenol compound from IO weight percent! Add θ heavy percent, ball mill, sand mill, attritor,
Dispersion is performed using a dispersing machine such as a colloid mill.

A coating liquid for heat-sensitive recording paper is prepared by adding oil-absorbing pigments, waxes, metal soaps, etc. as necessary to the mixture of the above dpi dispersion, and coating it on a support such as paper or plastic. , obtain the desired thermal recording paper.

The oil absorption if-'l includes kaolin, calcined kaolin,
It is selected from talc, waxite, cane earth, calcium carbonate, aluminum hydroxide, magnesium hydroxide, magnesium carbonate, titanium oxide, barium charcoal, urea-formalin filler, cellulose filler, and the like.

Examples of waxes include paraffin wax, cowna wax, microcrystalline wax, polyethylene wax, and higher fatty acid amides such as stearic acid amide and ethylene bis.

Examples of the metal soap include higher fatty acid polyvalent gold maple salts, such as zinc stearate, aluminum stearate, calcium stearate, and zinc oleate. isn't it.

Example 1 3-diethylamino-t-chloro-7-anilite fluora 720 f f / 0% polyvinyl alcohol (saponification degree '?I%, polymerization degree 000) and water-soluble tLlooy were dispersed in a 3θOml ball mill for one day. liquid(
A) was obtained.

Similarly, i0% benzyl p-hydroxybenzoate 20f
3001 with polyvinyl alcohol water-soluble yiooy
The mixture was dispersed in a 11-volume mill overnight to obtain a dispersion liquid CB).

Similarly, i,i,3-tris(2-methyl-≠-hydroxy-J--tert-butylphenyl)butane θy total io% polyvinyl alcohol aqueous solution 100g (1 and 300g were dispersed overnight in a ball mill to prepare a dispersion (C). Obtained.

Dispersion fj, (A), dispersion 1 (B) and dispersion liquid (C) 3
Further, 10 g of calcium carbonate fine powder was added to the mixed solution 2009 at a weight ratio of :/θ:j and sufficiently dispersed to prepare a coating solution.

This coating liquid for thermal recording paper was applied onto a base paper having a basis area of 1097 m2 so as to obtain a coating amount of t y /m2 in terms of solid content, and dried under SO80 for 2 minutes to obtain a thermal recording paper.

Example 2 A thermosensitive recording paper was obtained in the same manner as in Example, except that 20 g of ethyl p-hydroxybenzoate was used in place of 2 oyO of benzyl p-hydroxybenzoate in Example to obtain a dispersion (B).

Example 3 The procedure was repeated in the same manner as in Example 1, except that n-propyl p-hydroxybenzoate 209 was used instead of benzyl p-hydroxybenzoate λOf in Example 1 to obtain dispersion g(B). A thermosensitive recording paper was obtained.

Example 4 A thermosensitive recording paper was prepared in the same manner as in Example 1, except that p-oxybenzoic acid rhodutyl, 20Q, was used in place of p-hydroxybenzoic acid penzylco of Example 1 to obtain dispersion 1 (B). Obtained.

Example 5 Example/of/,/,! -) lis(2-methyl-≠-hydroxy-5-tert--ytylphenyl)butane 20
Instead of f, t, ≠'-thiobis(3-methyA/'-
A thermal Wf recording paper was obtained in the same manner as in Example 1, except that 1r-tert-butylphenol was used to obtain the dispersion <C).

Comparative Example 1 The dispersion liquid (A) of Example 1 and the dispersion liquid (Hl) were mixed at a weight ratio of 3:10, and jOQ calcium carbonate fine powder was added to 20Of the mixed liquid, thoroughly dispersed, and applied. The dispersion liquid (A) of Example 1 and the dispersion liquid (B) of Example 2 were prepared as follows:
=IO was mixed at a weight ratio of IO, and a heat-sensitive recording paper was obtained in the same manner as in Comparative Example.

Comparative Example 3 λ, -monobis(couhydroxyphenyl)furopane 10
F and stearic acid amide 10f were dispersed together with 7θ polyvinyl alcohol solution/OOQ in a 300-tan 1-hole mill overnight to obtain dispersion 9 (D).

Dispersion Q (A) of Example 1 and dispersion (D) of Comparative Example 3 were mixed at a weight ratio of 3=20, and the same procedure as in Comparative Example 1 was carried out to obtain a thermosensitive recording paper.

Comparative Test The relative softness test of the thermosensitive recording papers obtained in the above Examples and Comparative Examples was conducted as follows. .

(1) Capri and chromogenic main scanning j dots/m 7/J, Mll scanning 6 dots/mm density if, 2 mS/dot, somJ/m
m2 of energy is applied to the recording element to perform i-recording, and Macbeth 1'LD-si≠ type reflection a-1lit (using a visual filter) is used to detect fog (ground density before recording) and chromophore density after recording ( initial concentration) was measured.

(2) Colored material obtained in moisture resistance color development test After being left in an atmosphere of 6° C1 old 4° θ for 2≠ hours, the concentration of the colored material was measured.

The residual rate of the chromophore was calculated using the following formula.

Seitomo Hatsuro (3) The coloring material obtained in the heat resistance coloring test was heated to 4 o 0C, tLI.
After being left in an atmosphere of Iλθ for 2V, the concentration of the color former was measured. In addition, the residual rate of the colored body was calculated using the following formula.

initial concentration The results of the comparative test are shown in Table 1.

From the above table, it can be seen that the thermal recording paper of the present invention has higher color density and less decolorization than the comparative thermal recording paper.

Patent Applicant: Fuji Photo Film Co., Ltd. Procedural Amendment Date: 1932, 1939, Douichi, Commissioner of the Patent Office, Shima 1) Haruki Tono1, Indication of Case: 1944, Patent Application No. 1 r41
90W No. 2, Title of the invention: Thermal recording paper 3, Relationship with the amended case Patent applicant address: 210 Nakanuma, Minamiashigara City, Kanagawa Prefecture Contact address: Fuji Photo Film 2-1126-30 Nishi-Azabu, Minato-ku, Tokyo 106 Tokyo Honsho Denwa Co., Ltd. (406) 2537 4 Subject of amendment The detailed description of the "Detailed Explanation of Itomachi" in Mei A is amended as follows.

1) On page 9/line +, ``oxy'' and ``hydroxy'' and sode shocho 4).

2) fJJ/The first oxy on the left line is written as ``hydroxy.''

3) In the 10th Sadahiro line, "oxy" is changed to "hydroxy".

Claims (1)

[Claims] A thermal recording paper characterized by containing (a) a colorless electron-donating dye, (b) a p-hydroxybenzoic acid ester, and (C) a hindered phenol compound.