JPH02235684A - Thermally sensitive recording medium - Google Patents

Abstract

PURPOSE:To obtain a thermally sensitive recording medium which is highly responsive to heat and does not develop fog easily by adding a specific biphenylether compound as a coloring promoter. CONSTITUTION:4-(2-hydroxyethoxy)biphenyl and 4-(2-hydroxypropoxy) biphenyl are given as a compound shown by a formula. This compound can easily be obtained by allowing 4-phenylphenol to react with epoxide in a solvent such as alcohol, ketone or ether in the presence of basic material. The recommendable use amount of a biphenyl ether compound is 1 to 50%wt. of the total solid of a thermally sensitive layer. In addition, the recommendable leuco compounds are various derivatives of triphenyl methane, triphenylmethane phthalide and fluoran. The organic acids used are various phenol materials, aliphatic acid and aromatic carboxylic acid.

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial Application Field" The present invention relates to a heat-sensitive recording material, and particularly to a heat-sensitive recording material containing a color development accelerator.

"Prior Art" Conventionally, heat-sensitive recording materials such as heat-sensitive recording paper containing a leuco compound and an organic acid are already known, for example, from Japanese Patent Publication No. 45-i4039. Such thermal recording paper is based on the principle that thermal energy is applied to the thermal recording layer to soften or melt the leuco compound, organic acid, and binder, thereby bringing the two coloring components into contact and producing color. Recently, it has been used in various fields such as printers and facsimile machines.

Incidentally, the characteristics of such recording paper naturally differ depending on its use, and in recent years, more advanced recording paper has been required in this type of technical field. Therefore, for example, in order to increase the recording speed, it is of course necessary to improve the recording apparatus, but it is also required to simultaneously or incidentally improve the color development of the recording paper used.

However, as a method for promoting this coloring property, a method of incorporating a low melting point substance into the heat-sensitive recording layer is usually carried out.

Specifically, urea, phthalic anhydride, and acetanilide are used as low-melting substances, that is, color accelerators or sensitizers in Japanese Patent Publication No. 43-4160 (1982); Shima, carnauba wax, beeswax, wood wax, higher fatty acids, higher fatty acid esters; furthermore, in Japanese Patent Publication No. 17748/1974, salicylic acid, anisic acid,
Phthalic acid monophenyl ester and phthalic acid monobenzyl ester are described, and in recent years, the use of fatty acid amides as color accelerators has also been widely practiced.

Furthermore, Japanese Patent Publication No. 51-27-59-9 discloses the effect of promoting color development of fatty acid amide by the combination of paraffin or microwax and fatty acid amide;
No. 139740 describes the color development promoting effect of fatty acid amides such as stearic acid amide and oleic acid amide, and has been put to practical use. In addition, an improved method using monosubstituted 1,4-naphthohydroquinone derivatives such as 1,4-diethoxynaphculene has been proposed (Japanese Patent Application Laid-Open No. 127189/1989).

``Problems to be solved by the invention'' However, the heat-sensitive recording materials produced based on these methods using amide waxes such as stearic acid amide are still satisfactory in terms of color development sensitivity. sea bream. Various methods have been proposed to improve this, but inexpensive ones have problems with sublimation, thermal responsiveness, and fogging, while those with excellent thermal responsiveness are difficult to synthesize and are expensive. However, for practical purposes, it is still difficult to obtain sufficient products.

The purpose of the present inventors is to develop a color development accelerator that is relatively easy to synthesize, has low sublimation, has excellent thermal responsiveness, and can provide a thermal recording material that is resistant to fogging. It is in.

[Means and effects for solving the problems] As a result of intensive studies by the present inventors to solve these problems, 4-
The inventors have discovered that a biphenyl ether compound obtained by reacting phenylphenol with an epoxide is suitable for the above-mentioned purpose, and have arrived at the present invention.

That is, the present invention provides a heat-sensitive recording material mainly composed of a leuco compound and an organic acid that develops a color by reacting with the leuco compound, using 4-(2-hydroxyethoxy)biphenyl of general formula (1) as a color development accelerator (2) 4-(2-hydroxypropoxy)biphenyl (3) 4-(2-hydroxy-n-butoxy)biphenyl 11}1 (wherein Rl and R2 represent hydrogen or a lower alkyl group) A heat-sensitive recording material characterized by containing a biphenyl ether compound.

R1 and R2 in the general formula represent hydrogen or a lower alkyl group. In particular, the total number of carbon atoms is preferably 0 to 2.

Examples of the compound represented by the above general formula include the following.

These biphenyl ether compounds can be prepared by combining 4-phenylphenol with ethylene oxide, flobylene oxide, fluorine oxide, etc. in a solvent such as a alcohol such as methylalconopethyl alcohol, acetone, a ketone such as methyl ethyl ketone, or an ether such as tetrahydrofuran. It can be easily obtained by reacting an epoxide (epoxy compound) such as butylene in the presence of a basic substance such as sodium hydroxide.

These biphenyl ether compounds have a melting point of 80 to 1
It is in a particularly preferable range of 30°C, and when used as a color development accelerator for thermosensitive recording materials, it has an excellent color development promotion effect compared to conventionally used fatty acid amides and the like. In particular, the above compound-2 is excellent.

In the present invention, the amount of biphenyl ether compound used is 1 to 50% by weight, preferably 1 to 50% by weight of the total solid content of the heat-sensitive recording layer.
The intended purpose of the present invention can be achieved by setting the proportion to 0 to 40% by weight.

Leuco Compound The leuco compound used in the present invention can be any colorless or light-colored substance that reacts with an organic acid.

Examples include various derivatives such as triphenylmethane type, triphenylmethanephthalide type, fluoran type, leucoolamine type, diphenylmethane type, phenothiazine type, phenoxazine type, spirobilane type, impilin type, and indigo type.

More specifically, for example, the following can be suitably used (colors in parentheses indicate colors after color development).

Crystal violet lactone (blue), 3-diethylamino-6-methyl-7-anilinofluorane (black), 3-dibutylamino-6-methyl-7-anilinofluorane (black), 3-N,N- Ethylisoamylamino-6-methyl-7-anilinofluorane (black)
3-(N-ethyl-p-toluidino)-6-methyl-7-anilinofluorane (black) 3-diethylamino-6=methyl-7-(ortho, var. dimethylanilino) fluorane (black), 3- Virolidino-6-methyl-7-anilinofluorane (black), 3-piperidino-6-methyl-7-anilinofluorane (black), 3-
(N-cyclohexyl-N-methylamine)-6-methyl-7-anilinofluorane (black), 3-diethylamino-7-(ortho-roanilino)fluorane (black), 3-diethylamino-7-(meth trifluoromethylanilino) fluorane (black), 3-diethylamine-6-methyl-fluorane (red), 3-diethylamino-6-methyl-fluorane (red), 3-
Cyclohexylamino-6-chlorofluorane (orange)
, 3-(N-isoamyl-N-ethylamino)-6-methyl-7-anilinofluorane (black).

Organic acid (or ester thereof) The organic acid used in the present invention is a substance that is solid at room temperature, melts when heated, and becomes a color developer when it comes into contact with a leuco compound. Specific examples include various phenolic substances, fatty acids, aromatic carboxylic acids, and the like.

In the present invention, various objects of the present invention can be achieved by setting the amount of the organic acid used in a proportion of 1 to 40% by weight of the total solid content of the heat-sensitive recording layer.

More specifically, the following are used.

Gallic acid, salicylic acid, ■-hydroxy-2-naphthoic acid, 0-hydroxybenzoic acid, m-hydroxybenzoic acid, IJ
F acid, 2-hydroxy-p-}ruylic acid, 3,5-xylenonopetimol, p-tert-butylphenol, 4-hydroxyphenoxide, methyl-4-hydroxybenzoate, 4-hydroxyacetophenone, α
- Naphthol, β-naphthol, catechol, resorcinol, 4-tert-octylcatechonobe 4.4'-s
ec-butylidenephenol, 2. 2'-dihydroxydiphenyl, 2. 2'-methylenebis(4-methyl-5-tert-butylphenol), 2.2'
-bis(4-hydroxyphenyl)propane (another bisphenol A), 4,4'-isopropylidene-bis(2-tert-butylphenol), birogallol, phloroglycine, phloroglucincarboxylic acid.

p-methylphenol, p-tert-7”f
p-phenylphenol, 4,4'-cycloheylidene diphenol, 4,4'-(1-methyl-n-hexylidene) diphenol, 4,4'-(isobropylidene) dicatechol, 4.4 '-benzylidene diphenol, 4.4'-isobropylidene bis(
2-chloropher), 3-phenylsalicylic acid, 3,
5-di-tert-butylsalicylic acid, 1-oxy-2
- Naphthoic acid, gallic acid ester, salicylic acid ester, 4-hydroxyphthalic acid ester.

Binder In the present invention, a known binder is used. Note that it is desirable to use a water-soluble one.

The binder functions to separate and fix the coloring agent dispersed in fine particles from each other. Specifically, polyvinyl alcohol, methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, polyacrylic acid, casein, gelatin, starch, and derivatives thereof are used.

In the present invention, various objects of the present invention can be achieved by adjusting the amount of the binder used in a proportion of 1 to 35% by weight, preferably 10 to 30% by weight of the total solid content of the heat-sensitive recording layer. Ru.

Other Additives The heat-sensitive recording material of the present invention may further include other additives in the heat-sensitive recording layer as necessary, such as inorganic additives such as clay, silica, calcium carbonate, aluminum hydroxide, talc, titanium oxide, zinc oxide, etc. Alternatively, organic pigments, waxes, antioxidants for storage stability, ultraviolet absorbers, various fatty acid metal salts to prevent stickiness, water resistant agents to improve water resistance, phenolic resins, surfactants, etc. are added. You can.

Furthermore, in combination with the color development promoter according to the invention, color development promoters already known in this type of technical field may be added.

Substrate Various types of paper, including wood-free paper, medium-quality paper, and coated paper, are usually used as the substrate for use in the present invention. In the present invention, other materials such as glass fiber sheets, plastic sheets, film laminates, etc. can also be used as the substrate.

Hereinafter, the configuration and effects of the present invention will be explained in more detail by way of examples. However, the technical scope of the present invention is not limited to these examples.

"Example" Experimental example The biphenyl ether compound of the present invention and a known compound (
For example, regarding the sublimation of 1.4-jetoxynaphthalene), thermal lightning measurement equipment (differential scanning calorimeter, Rigaku Denki Th
The weight loss due to heat was measured using an ermo flex TG-DSC (standard type) and compared.

The results are shown in Table 1.

Each given sample was heated to 200°C at a heating rate of 10°C/min.
and the temperature was raised to 250°C. All of the alkoxyluponyloxy compounds of the present invention were able to lower the sublimation property compared to 1,4-diethoxynaphthalene as follows.

Table 1 Synthesis Example 1 Synthesis of r4-(Z-hydroxypropoxy)biphenyl Sodium hydroxide was added to a solution of 34 g (0.20 mol) of 4-phenylphenol and 23.2 g (0.40 mol) of propylene oxide in 60 mj2 of methyl alcohol. 8g of 301 aqueous solution was added. After heating at 50℃ for 2 hours, let it cool and soak in 30r of water.
nl was added. The precipitated crystals were filtered, thoroughly washed with water, and then dried to obtain 35 g (0.153 mol) of white crystals.

The melting point of this product is 122-123℃, IR, NM
R. Elemental analysis confirmed that it was 4-(2-hydroxypropoxy)biphenyl.

Identification data Molecular formula C 16 H ls○2 I R (K B r ) 3400. 297
0. 2930, 2880. 1610, 1525.
1490. 1460, 1340. 1290,1
275, 1260, 1,200, 1045, 8
40,760. 690 (cm-')'H NMR (CDCI3.6 0M7) δ 1.
3 (d, J=6Hz, 3H), 2. 5
(d. J=4Hz. 1N), 3.3.8 ~4
．． 0 (m, 2H), 4.0 to 4.3 (m.IH), 7
, 03 (d, J=9Hz. 2H) , 7. 3
~7. 8 (rn, 7}1) C H cal
cd, C 78. 92% H7, 06%f
ound, C 79.77% 8 7.0
1% Synthesis Example 2 Synthesis of r4- (2-hydroxyethoxy> biphenyl) 2 g of sodium hydroxide is added to a solution of 8.5 g (0.05 mol) of 4-phenylphenol and 22 g (0.50 mol) of ethylene oxide in 25 ml of methyl alcohol. After heating at 50°C for 2 hours, it was allowed to cool, and 15 ml of water was added.The precipitated crystals were filtered, thoroughly washed with water, and then dried to give 6.8 g (0.026 mol) of white crystals. The melting point of this product was 104-105°C, and IRSNMR,
Elemental analysis confirmed that it was 4-(2-hydroxyethoxy)biphenyl.

Identification data Molecular formula CI 4 H + s○2I R (KB
r) 3300.2940.2880,160
8.1521,1490. 1450. 1290.
1270, 1260, 1200, 1095. 10
55, 920, 835, 760, 690 (cm
-')'H NMR (CDCI3.60M7)6 2.
5(br, 1}1), 3. 5-3. 8 (m.
2}1),3. 8-4. 2 (m. 2H).
7. 05 (d, J=8Hz, 2H)7. 2
~7. 7 (m, 7H) C H calcd
, C 78. 48% 8 6.59%f
ound, C 78.40% H 6.
70% Synthesis Example 3 "Synthesis of r4-(2-hydroxy-2-methylbropoxy)biphenyl" 4-phenylphenol 17g (0.10 mol), 2-
A solution of 22 g (0.30 mol) of methyl propylene oxide in 40 ml of methyl alcohol was added with 4 g of sodium hydroxide.
rnf! Aqueous solution was added. After heating at 50℃ for 2 hours, let it cool and add 20m7 of water! added. The precipitated crystals were filtered, thoroughly washed with water, and then dried. 0 g (0.0 8
2 mol) of white powder was obtained. The melting point of this thing is 105~
The temperature was 106℃, and IRSNMR and elemental analysis showed that 4-
It was confirmed that it was (2-hydroxy-2-methylproboxy)biphenyl.

Identification data Molecular formula C + g H + s O 2I R (
KB r) 3400, 2980.2925.1
608.1525, 1490.1380. 1290.
1270. 1255.1200. 1180. 1
050, 830, 760.690 (Cm″″′) 'H NMR (CDCI3.6 0MHz)
δ 1. 3(s, 6H), 2. 4 (s. I
H). 3. 85(S, 2H>, 7. 03(d,
J=9Hz, 2tl), 7. 3-7. 8(
m, 7H ) C H calcd, C
79. 31%H 7.49%found,
C 79.18% H 7.41% Synthesis Example 4 "Synthesis of r4- (2-hydroxy-n-butoxy)biphenyl" 17 g (0.10 mol) of 4-phenylphenol, 1.
2 In a solution of 21.6 g (0.30 mol) of butylene monoxide in 30 mA' of methyl alcohol, 4 g of sodium hydroxide is added.
5 ml aqueous solution was added. After heating at 50°C for 2 hours, let it cool.
10 - of water was added. The precipitated crystals were filtered, thoroughly washed with water, and then dried.18. 1 g of white powder was obtained. The melting point of this product is 111-112°C, and IRSNMR,
By elemental analysis, 4-(2-hydroxy-n-butoxy)biphenyl? I was sure that.

Identification data Molecule 2 C + s H t s O■( R (K
B r ) 3400. 2940, 288
5. 1610. 1525, 1490. 1455.
1345. 1290. 1275, 1260, 1
200. 1140, 1055. 990,880,
840, 760, 690 (cm-')'H
NMR (CDCI., 60MHZ) δ 1. O
(t, J=7Hz, 3H). 1. 57 (dq
, J+=7Hz, J2=6Hz, 2H) ,2
．． 43 (br, IH), 3. 9-4. 2(
m. IH). 7. 07 (d, J=9Hz. 2
H). 7. 3-7. ? (m.7H) C H
calcd. C 79. 31% H 7.49
%found, C 79.40% H 7
．． 50% Example 1 and Comparative Example (1) Production of heat-sensitive recording paper Liquids A and B having the following compositions were separately ground and dispersed in a ball mill for 72 hours.

8-part aluminum hydroxide zinc stearate polyvinyl alcohol 105 (made by Kuraray) 12% solution water B solution Bisphenol A Calcium carbonate zinc stearate polyvinyl alcohol 105 (made by Kuraray) 12% solution water Next, 125 g of solution A, B 125g of liquid, polyvinyl alcohol 105 (@ J Kuraray) 50g of 12% liquid, 40g of water
g was mixed and stirred to form a thermosensitive coloring layer forming liquid, and this was applied to the surface of 50 g/m' high-quality paper using a wire bar so that the coating amount after drying was 8 g/rn'. ,
It was dried to produce thermosensitive recording paper.

(2) Test of thermal recording paper The recording surface of the thermal recording paper obtained in the above Examples and Comparative Examples has Beck smoothness. The surface was treated with a super calender for 500 seconds.

Next, the following tests were performed on each of the obtained thermal recording papers, and the results are shown in Table 2.

■ Color development start temperature Ts This is the temperature at which the color density becomes 0.2 in a static color development test.

■Image density Commercially available thin film thermal head KFT-216-8MPDI
(manufactured by Kyocera ■) Printing power Q, 7 Q w/dot
Solid printing was performed under the conditions of , pulse width Q, and gms, and the print density at that time was measured using a Macbeth densitometer RD-514.

Table 2 "Effects of the Invention" The biphenyl ether compound of the present invention is relatively easy to synthesize, has low sublimation, and when used as a color accelerator, has excellent heat responsiveness and is resistant to fogging. A recording body is obtained.

Claims (4)

[Claims] (1) In a heat-sensitive recording material whose main components are a leuco compound and an organic acid that develops color by reacting with the leuco compound, there are general formulas ▲mathematical formulas, chemical formulas, tables, etc.▼ (in the formula, R ^1 and R^2 represent hydrogen or a lower alkyl group. (2) The heat-sensitive recording material according to claim 1, wherein the total carbon number of R^1 and R^2 in the general formula is 0 to 2. (3) The heat-sensitive recording material according to claim 1, wherein the biphenyl ether compound is 4-(2-hydroxypropoxy)biphenyl. (4) The melting point of the biphenyl ether compound is 80 to 130
2. The heat-sensitive recording material according to claim 1, wherein the temperature is .degree.