JPS60255486A - heat sensitive recording material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a heat-sensitive recording material, and particularly to a heat-sensitive recording material that has excellent color development and other recording suitability, and has good image stability.

[Prior art]

In recent years, various recording methods have been researched, developed, and put into practical use in the field of information recording in response to social demands such as the diversification and increase of information, resource saving, labor saving, and non-pollution. The heat-sensitive recording method using heat-sensitive recording materials has the following features: ■) A colored image is recorded simply by heating, eliminating the need for a complicated development process; ■) It is possible to record images using a simple and compact device, and it is easy to obtain. ■) Since paper can be used as a support, not only is the support cost low, but the feel of the resulting recording sheet is similar to that of plain paper. Because of its advantages such as being close to the computer, it has been put to practical use in computer output, medical measurement recorders, facsimiles, printers, PO5 labels, tickets for vending machines, etc. The heat-sensitive recording material used in such a recording method includes lagton,
A heat-sensitive color-forming layer containing a colorless or light-colored leuco dye having a lactam or spiropyran ring and an acidic substance such as an organic acid or a phenolic compound as a color developer that develops color when heated (Japanese Patent Publication No. 43 -4160 No. 4
No. 5-14039, etc.) are publicly known. 1. In recent years, with the development of society, the demand for faster and higher recording density has been increasing with the heat-sensitive recording method using such heat-sensitive recording materials. There is a strong desire to increase the speed (ie, increase the sensitivity) of heat-sensitive recording materials themselves.

Conventionally, as a method for increasing the sensitivity of heat-sensitive recording materials, various waxes, fatty acid amides, alkylated biphenyls, substituted biphenylalkanes, coumarins, and diphenylamines are added to a normal leuco-based heat-sensitive coloring layer as sensitizers or melting point depressants. Heat-sensitive recording materials to which low melting point thermofusible substances are added are known, for example, JP-A-53-39137, JP-A-53-26139, JP-A-53-5636, JP-A-53- It is introduced in Publication No. 11036, etc. However, even in such heat-sensitive materials, it cannot be said that sufficient thermal responsiveness is achieved to meet the demands for high-speed recording.

On the other hand, it is known that when a specific phenolic compound is used as a color developer for leuco dye, a heat-sensitive material with good heat responsiveness can be obtained, and it is widely used in the field of high-speed heat-sensitive recording. However, in the case of this type of leuco-based heat-sensitive recording material, the stability of the recorded image is poor, and for example, the recorded image is easily discolored when it comes into contact with oils or plasticizers such as dioctyl phthalate contained in plastic films. There is a drawback.

Conventionally, in order to improve the stability of recorded images, for example, a thermosensitive coloring layer containing a large amount of water-resistant and chemical-resistant resin, a thermosensitive coloring layer containing a resin that hardens by heat or light,
Alternatively, a method has been proposed in which a resin protective layer is formed on the surface to protect the heat-sensitive coloring layer from the effects of chemicals and water, but this method complicates processing, increases costs, and also reduces thermal responsiveness. It has the problem of being stored away. On the other hand, pressure-sensitive materials using chemical-resistant color developers have been proposed, such as JP-A-48-5+,
No. 716, Special Publication No. 51-25174, etc. Although this color developer is useful for pressure-sensitive materials, when used for heat-sensitive recording materials, when the recorded image comes into contact with a plasticizer, the colored areas are stable, but the background areas (non-colored areas) are stable. ) has the disadvantage of causing color development. Also, JP-A-59-112
When most of the color developers described in No. 86 "Pressure-sensitive or heat-sensitive recording materials" are used in heat-sensitive recording materials, the initial density at the background part is high (texture strength °buri), resulting in extremely low-quality heat-sensitive recordings. You can only get the materials. Furthermore, like the color developers used in the field of pressure-sensitive materials, the color developer in this case also has the disadvantage of causing color development in the background when it comes into contact with a plasticizer.

As described above, the current situation in the conventional heat-sensitive recording field is that a sufficient heat-sensitive recording material that simultaneously satisfies good thermal responsiveness suitable for high-speed recording and stability of recorded images has not been obtained.

〔the purpose〕

The purpose of the present invention is to have excellent coloring properties suitable for high-speed recording, and also to provide extremely high sensitivity and high image reliability without decoloring the coloring area or coloring the background area even when in contact with oils, plasticizers, etc. The objective is to provide reliable heat-sensitive recording materials.

〔composition〕

According to the present invention, as a color developer for leuco dye, an antipyrine complex of zinc thiocyanate represented by the following formula (1) and a phenolic compound represented by the following general formulas (II), (m) and (IV) are used. Provided is a heat-sensitive recording material characterized by using a combination with at least one selected from the following.

Formula (I) General formula (■): (In the formula, R1 represents an alkyl group having 1 to 7 carbon atoms, a substituted or unsubstituted phenyl group, or a substituted or unsubstituted benzyl group) General formula (■) : (In the formula, R2 and R3 represent an alkyl group having 1 to 7 carbon atoms, a substituted or unsubstituted phenyl group, or a substituted or unsubstituted benzyl group, and R2, and R3 may be the same or different. ) General formula (■): (In the formula, R4 has 1 to 3 ether bonds and has 2 carbon atoms
~10 alkylene groups) In the general formula (old and (m)), substituted phenyl or substituted benzyl is halogen, alkoxy,
Includes those substituted with alkyl groups, halomethyl groups, etc.

Specific examples of the compound represented by the above general formula (II) include the following.

Specific examples of the compound represented by the above general formula (Ilj) include the following.

Shirisushi I'+3 - Specific examples of the compound represented by the above general formula (■) include the following.

H3 In the present invention, the ratio of the antipyrine complex of zinc thiocyanate of formula (1) and the compound of general formulas (IT) to (mV) is thiocyanic acid of formula (1)! 11 (For 1 part by weight of the button antipyrine complex, general formula (IT) ~ (1v)
The proportion of the compound is preferably 173 to 10 parts by weight, preferably 1 to 5 parts by weight.

As the leuco dye used in the present invention, any one that is normally applied to this type of heat-sensitive material can be used, and leuco compounds such as triphenylmethane, lactone or fluoran, and pentufuran are preferred. used. Specific examples of such leuco dyes include those shown below.

Crystal violet lactone, malachite green lactone, 1-diethylamino-6-methyl-7-chlorofluoran, 3-(N-ethyl-pt-luidino)-6-methyl-
7-anilinofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 3-piperidino-methyl-7-anilinofluorane, 3
-diethylamino-6-methyl-7-(o,p-dimethylanilino)fluorane, 3-(lj-cyclohexyl-N-methylamino)-6
-Methyl-7-anilinofluoran, 3-diethylamino-7-(0-chloroanilino)fluoran, 3-(dinorbutylamino)-7-(o-chloroanilino)fluoran.

3-diethylamino-7-(m-trifluoromethylanilino)fluorane, 3-(isoamyl-N-ethylamino)-6-methyl-
7-anilinofluorane, 3-diethylamino-6-methylfluorane, 3-cyclohexylamino-6-chlorofluorane, and the following leuco dyes can be used alone, or two or more of them can be mixed or layered. and used.

Furthermore, the leuco dye, the antipyrine complex of zinc thiocyanate of formula (1), and the phenolic compounds of general formulas (II) to (IV) may be used as a mixture or in a layered manner. Here, the color developer consisting of a combination of the compound of formula (1) and at least one of general formulas (TI) to (IV) is generally used in an amount of 1 to 6 parts by weight per 1 part by weight of the leuco dye. It is preferable to use

In addition, in the heat-sensitive coloring layer of the present invention, various commonly used binders may be appropriately used for bonding and supporting on the support, such as polyvinyl alcohol, methoxycellulose, hydroxyethylcellulose-srivinylpyrrolidone, Water-soluble materials such as polyacrylamide, polyacrylic acid, starch, gelatin, etc.
Alternatively, aqueous emulsions such as polystyrene, vinyl chloride-vinyl acetate copolymer, polybutyl methacrylate, etc. can be used as the binder.

In addition, in the present invention, if necessary, auxiliary additive components commonly used in this type of heat-sensitive recording material, such as fillers,
A surfactant, a thermofusible substance, a lubricant, etc. can be used in combination. In this case, fillers include, for example, calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, and surface-treated inorganic fine powders such as calcium and silica. .

Organic fine powders such as urea-formalin resin, styrene/methacrylic acid copolymer, and polystyrene resin can be mentioned, and examples of the thermofusible substance include higher fatty acids or their esters, amides, or metal salts. , various waxes, condensates of aromatic carboxylic acids and amines, benzoic acid phenyl esters, higher linear glycols, dialkyl 3,4-epoxy-hexahydrophthalates, higher ketones, other thermofusible organic compounds, etc. Examples include those having a melting point of about 50 to 200°C.

The heat-sensitive recording material of the present invention can have various structures. For example, a coating solution for forming a heat-sensitive recording layer containing the above-mentioned components is coated on a suitable support such as paper, synthetic paper, or plastic film. Manufactured by applying and drying
Thermal labels for PO5, which often come into contact with oils, plasticizers, etc., are used in various recording fields, such as thermal tickets, recorders for medical measuring instruments, and thermal paper.

〔effect〕

According to the present invention, an antipyrine complex of zinc thiocyanate represented by the above formula (I) and a phenolic compound represented by the above general formulas (n), (m) and (IV) are used as a color developer for leuco dyes. By using a combination with at least one kind, a heat-sensitive recording material having the excellent properties listed below can be obtained.

(1) The compound of the above formula (1) can be easily synthesized with high yield and high purity, and therefore there is no problem in obtaining raw materials, so a heat-sensitive material can be obtained at a relatively low cost.

(2) It has excellent color development suitable for high-speed recording, and
Even if it comes into contact with oils, plasticizers, etc., the color developing area will not fade or the background area will develop color, resulting in high stability of recorded images.

〔Example〕

Examples of the present invention are shown below.

Synthesis Example 14.4 g of zinc sulfate (ZnSO4.7H20) and 29.2 g of potassium thiocyanate were dissolved in 200 mβ of water. Separately, a solution of 18.8 g of antipyrine dissolved in 200 m of water was prepared and added dropwise to the bipedal solution while stirring, immediately forming a white precipitate. This precipitate was filtered, washed with water, dried, and the obtained white powder was recrystallized from a mixed solvent of water and ethanol to obtain 24.2 g of white crystals of an antipyrine complex of zinc thiocyanate with a melting point of 118 to 120°C. .

Example 1 A mixture consisting of the following silk compositions was separately ground for two days using a magnetic ball mill and dispersed to form (A) solution.

Solution (B), solution [C] and solution [D] were prepared.

(A) Liquid 3-(N-cyclohexyl-N-methylamino)-6-
Methyl-7-anilitofluorane 20 parts by weight 10% hydroxyethyl cellulose aqueous solution 20 Water 60 Liquid (B) Antipyrine complex of zinc thiocyanate 20 parts by weight 5% methylcellulose aqueous solution 20 Water 60 [C] Liquid P -Hydroxybenzoic acid benzyl ester (compound of developer specific example (4)) 20 parts by weight 10% hydroxyethyl cellulose aqueous solution 20 Water 60 CDl liquid Fine powder of urea-formalin condensation resin 20 parts by weight 5% methyl cellulose aqueous solution 20! 1 water 60 IJ Using the solutions (, A) to [D] obtained as above,
A heat-sensitive color forming layer solution having the following composition was prepared, and applied to a commercially available high-quality paper with a standard basis weight of 50 g/I using a wire bar at a dry coating amount of 4 to 5 g/rrF, and dried, and then smoothed on the surface of the heat-sensitive color forming layer. The heat-sensitive recording material of the present invention (
I made a).

Thermosensitive coloring layer liquid (1) (A) liquid 10 parts by weight (2)' [B] liquid 3017 (3) [C) liquid 30! I ('4) CD) Solution 30 n (5) 20% alkaline aqueous solution of isobutylene-anofomaleic acid copolymer 10 Example 2 The following solution (E) is used in place of solution (B) in Example 1. Thermal recording material (b) was prepared in the same manner as in Example 1 except for
made.

(E) Liquid 4-Hydroxyphthalic acid dimethyl ester (compound of developer specific example (9)) 20 parts by weight 10% hydroxyethyl cellulose aqueous solution 20゛〃 Water 60〃 Example 3 Example 1 [instead of CD solution] Heat-sensitive recording material (c) was prepared in the same manner as in Example 1 except that the following CF) liquid was used.
made.

CF) liquid 1.7-di(4-hydroxyphenylthio)-3,5-
Dioxahebutane (specific example of color developer - substance (21)) 20 parts by weight 10% hydroxyethyl cellulose aqueous solution 20 Water 60/J Comparative Example 1 In Example 1, [the use of CD solution was stopped and (C) solution was used] A heat-sensitive i2 recording material (d) was prepared in the same manner as in Example 1, except that the amount of liquid [I3] was increased by the amount of [I3].

Comparative Example 2 A heat-sensitive recording material (e) was prepared in the same manner as in Example 1 except that the following liquid (G) was used instead of the liquid CB) in Example j.
made.

[G] Liquid imidazole complex of zinc thiocyanate (melting point 143-145°C) 20 parts by weight 5% methylcellulose aqueous solution 20 / J water 60! l Comparative Example 3 A heat-sensitive recording material (
f) was made.

[I''] Liquid bisphenol A 20 parts by weight 10% Hydroxyethyl cellulose 20 parts by weight Aqueous solution 60 Comparative example 4 The use of liquid [8) in Example 1 was stopped, and the amount of CD liquid was increased by the amount of liquid (8). A thermosensitive recording material (g) was produced in the same manner as in Example 1 except for this.

Comparative Example 5 A heat-sensitive recording material (h) was produced in the same manner as in Example 2, except that the use of the [B] solution in Example 2 was discontinued, and the amount of the [E) solution was increased by the amount of the CBE solution.

Comparative Example 6 A heat-sensitive recording material (1) was produced in the same manner as in Example 3, except that the use of liquid [B] of Example 3 was discontinued, and the amount of liquid (CF) was increased by the amount of 81 liquids.

Thermosensitive recording materials (a) to (i) obtained as above
was printed at 150° C. using a thermal gradient tester (manufactured by Toyo Seiki) at a pressure of 2 kg and a contact time of 1 second. Apply a thin layer of cottonseed oil to the colored part and the background part of the heat-sensitive recording materials (a) to (i), and place it indoors for 24 hours.
After leaving it for a while, I looked at the changes in the colored area and the background area. As a result, the heat-sensitive recording materials (a) of Examples 1 to 3 and Comparative Examples 1 and 3
, (b), (c), (d) and (f), neither decoloring of the colored area nor coloring of the background area was observed, but in the heat-sensitive recording material (e) of Comparative Example 2, decoloring of the colored area was observed. Although there was no color development on the skin, color development was observed. Also, comparative example 4゜5
In heat-sensitive recording materials (g), (h), and (i), no color development was observed in the background areas, but the color development areas were almost completely decolored.

Next, print the heat-sensitive recording materials (a) to l) in the same manner, cut out 4 cm squares around the printed area, and cover this with polyvinyl chloride film (Polywrap V-3 manufactured by Shin-Etsu Polymer Co., Ltd.).
00), and after applying a load of 500 g/cJ at room temperature for 24 hours, take it out, measure the density of the background part and the density of the colored part with a Macbeth densitometer (RD-514), and compare it with the density before the test. did. The results are shown in Table-1.

Table 1: Polyvinyl chloride film test method: Heat-sensitive recording sheets (a) to (c) were used with Matsushita Electronic Parts (
Head power: 0.451+l/Ft, J line recording time: 2 using thermal printing experimental equipment with thin film head manufactured by Co., Ltd.
0m5ec/n.

Print with a pulse width of 1.6.2.0.2.4 (msec) under the conditions of a scanning density of 8 x 3.85 dots/mm, and measure the print density using a Macbeth densitometer R1)-s+4 (Fi/L/meter Il+). -106) Measured. The results are shown in Table-21.

From Table 2, ]2, it can be seen that the heat-sensitive recording material of the present invention does not have the disadvantages of decoloring of the colored area and coloring of the background area when it comes into contact with oils, plasticizers, etc. It can be seen that it is an extremely excellent heat-sensitive recording material with good color development.

1 person for patent Ricoh Co., Ltd. - Agent Patent Attorney Toshiaki Ikeura Proceedings Amendment Document dated February 1982, Patent Application No. 112769 2, Name of invention Thermal Recording Material 3, Person making the amendment Relationship to the incident Patent applicant address: 1-3-6 Nakamagome, Ota-ku, Tokyo Name (
674) Ricoh Co., Ltd. - Representative Hama 1) Hiro 4, Agent 〒151 Address 1-58-10-5 Yoyogi, Shibuya-ku, Tokyo Date of amendment order Voluntary 6 Number of inventions increased by amendment.

8. Contents of amendment The following amendments will be made in the specification of this application.

(1) On page 16, lines 9 and 10, "Thermal label for R POS" will be corrected to "Thermal label for R POS".

(2) On the bottom line of page 19, "Instead of liquid CB) of Example 1" was changed to "In place of (C,] liquid of Example 1" iF
, Shimasu.

(3) 7th line from the bottom of page 24 [Thermal recording sheet (a)
~(c)'' to ``Thermal recording paper (a)~(i)'' to J.

Claims (1)

[Claims] (1) In a heat-sensitive recording material in which a heat-sensitive coloring layer containing a leuco dye and a color developer is provided on a support, the color developer may be a compound represented by the following formula (already expressed) and a compound represented by the following general formula (I
A heat-sensitive recording material characterized by using a combination with at least one selected from phenolic compounds represented by I), (III) and (rV). Formula (■) General formula (■): (In the formula, R1 represents an alkyl group having 1 to 7 carbon atoms, a substituted or unsubstituted phenyl group, or a substituted or unsubstituted benzyl group) General formula (■) : (In the formula, R2 and R3 represent an alkyl group having 1 to 7 carbon atoms, a substituted or unsubstituted phenyl group, or a substituted or unsubstituted benzyl group, and R2 and R3 may be the same or different.) General formula (■): (In the formula, R4 represents an alkylene group having 2 to 10 carbon atoms and having 1 to 3 ether bonds)