JPS60210490A - Thermal recording sheet - Google Patents

Abstract

PURPOSE:To enhance stability of developed color images and minimize the deterioration of stability of a blank paper, by providing a layer comprising one or more specified stabilizers between a colorless or light-colored electron-donative color forming substance and a thermal color forming layer. CONSTITUTION:A layer comprising one or more stabilizers selected from 1,1- bis(4-hydroxyphenyl)cyclohexane, 1,3,5-tris(4-t-butyl-3-hydroy-2,6-dimethyl)isocyanuric acid, 4,4'-thiobis(3-methyl-6-t-butylphenol) and benzyl p-benzyloxybenzoate is provided between a colorless or light-colored electron-donateive color forming substance and a thermal color forming layer comprising an acidic substance for developing the color of the color forming substance when being heated. Accordingly, since the stabilizer layer and the thermal color forming layer are provided separately form each other, the stabilizer is not brough into contact with the color forming layer or the developer at a white part at which the sheet is not heated by a thermal head, so that the brightness of the paper is maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-sensitive recording sheet, and more particularly, the present invention relates to a heat-sensitive recording sheet containing a specific stabilizer between a support and a heat-sensitive layer. By forming a thin layer, the stability of the colored image is improved, and the blank area (uncolored area) is extremely resistant to deterioration or discoloration due to changes in environmental conditions due to changes in temperature and humidity. This invention relates to a heat-sensitive recording sheet that can maintain good stability.

As is well known, a thermosensitive recording sheet is a sheet in which a thermosensitive coloring layer containing a colorless or light-colored electron-donating coloring substance and a phenolic substance is formed on a support. It is now widely used with the spread of similar products. This device requires the inclusion of the electron-donating color-forming substance and the acidic substance in the heat-sensitive recording layer, but recently, in order to further improve the stability of colored images, It is customary to coexist various stabilizers.

The stability of the colored image here refers to heat resistance, moisture resistance, and fingerprint resistance, and means that the colored image does not fade or discolor even when it comes into contact with heat, humidity, or oil attached to the skin. means.

But 1. If the stabilizer coexists with an electron-donating color-forming substance or an acidic substance (a 1-monol compound), the stability of the color image will be 1.1. Because the blank areas lack stability, the blank areas tend to become discolored during storage.

In order to improve the drawbacks mentioned in -1-, the inventors of the present invention have made efforts to incorporate a specific stabilizer (described later) between the support and the heat-sensitive coloring layer. We have found that by forming a layer that has a uniform color, it is possible to improve the stability of colored images (11) and to minimize the deterioration in stability (deterioration and discoloration) that occurs in blank areas. , completed the invention.

In other words, the present invention provides 1.1 bis(4
-Human ITI 4'-diphenyl)cyclohexane, 1.3.51-lis(4-1-butyl-3-hydroxy-2,6-dimedyl)yl-1-nocyamic acid, 4.4'-diA bis(3-methyl -6-1-butylphenol), benzyl parabenzyloxybenzoate, or two
It consists of providing a layer containing one or more stabilizers (hereinafter referred to as stabilizer layer).

In the present invention, by forming the specific stabilizer layer (described above) between the heat-sensitive color forming layer and the support, the white area (uncolored area) in particular will not change in quality or discolor even under changes in environmental conditions. Although the factors that are extremely small and can maintain the original whiteness of paper must depend on experimental results rather than on the paper, according to the experimental results of the present inventors, the above-mentioned whiteness formed on the support By making the stabilizer layer and the heat-sensitive coloring layer separate layers, in the white area that is not heated by the thermal head, there is no contact between the stabilizer and the electron-donating coloring substance or color developer, and even if there is, that contact will not occur. It is thought that the stability of the white part is good and that the original whiteness of the white part can be maintained and maintained.

On the other hand, in the colored image area heated by the thermal head, the electron-donating color forming substance, the color developer, and the stabilizer in the stabilizer layer melt and contact each other to sharpen the colored image, and at the same time,
It is thought that this method can improve the stability 11.

Conventionally known colorless to light-colored electron-donating color-forming substances used in the present invention include, for example, 3-N-cyclohexyl-N-methylamino-6-methyl-anilinofluorane, 3-di-n-butyl Amino-7-(2' chloroanilino)fluoran, 3-di-n-ethyl-7-(2' chloroanilino)fluoran, 3-N-ethyl-N-isopentyl-amino-6-
Methyl-7-anilinofluorane, 3-N-diethylamino-6-methyl-7-anilinofluorane, 3-N
-Methyl-N-(p-tolyl)amino-7-anilinofluorane and the like can be arbitrarily selected.

As a color developer, 4,4'-isopropylidenediphenol and 2,2'-dihydroxydiphenol are used.

Benzyl paraoxybenzoate, butyl paraoxybenzoate, dimethyl 4-hydroxyphthalate, diethyl 4-hydroxyphthalate, β-nophthalate.

Examples include, but are not limited to, 5-novolac type phenol resins.

'', in order to put the stabilizer into practical use, the required amount can be ground to a particle size of 5 μm or less using a grinder such as a ball mill, attritor, or sanido grinder, but in this case, polyvinyl alcohol methyl cellulose, Styrene/maleic anhydride copolymer, vinyl acetate/maleic anhydride copolymer.

Styrene-butadiene copolymer, casein, gelatin,
Addition of binders such as gum arabic, and talc, clay, calcium carbonate, calcined seaweed. Particulate anhydrous silica, aluminum silicate.

Inorganic pigments such as aluminum hydroxide and organic pigments such as plastic pigments can also be added.

The amount of the stabilizer to be used is determined depending on the required performance and recording suitability and is not particularly limited, but the amount of the stabilizer applied to the support surface after drying is 0.5 to
7. Oo/Td preferably 1.0-5.0g/TIF.
It is.

6 - On the other hand, a colorless or light-colored electron donor f! I5R, colored substances and acidic substances are crushed by a grinder until they have a particle size of 5 μm or less in the same way as the stabilizer, and various additives are added depending on the purpose of use to obtain a coating liquid. Usually, binders and pigments similar to stabilizer coating liquids are added, and lubricants such as fatty acid metal salts, fatty acid amides, and fatty acid esters, 1-lyazole-based or benzophenone-based ultraviolet absorbers, and water-resistant agents such as glyoxal are added. It is also possible to add a curing agent.

The present invention will be explained in more detail below using examples (including comparative examples).

However, all "parts" in this example bulletin indicate "parts by weight."

Example 1 (1) Formation of the first layer 1.1-bis(4-hydroxyphenyl)cyclohexylamine 10.9 parts Polyvinyl alcohol (10% aqueous solution) 27.3 parts Water 61.8 parts Above composition The desired coating liquid was obtained by pulverizing the material using a ball mill for 24 hours until the average particle size was 3 μm.Then, this coating liquid was coated on high-quality paper with a basis weight of 50 (+/711) so that the coating amount after drying was 2 g/ It was coated to give Td.

(2) Formation of second layer 3-N-Methyl-N-cyclohexylamino-6-methyl-fluorane 10 parts Polyvinyl alcohol (10% aqueous solution) 25 parts Water 65 parts The above composition was milled in a ball mill. 24 hour average particle size is 3μ
A solution A was obtained by pulverizing the powder until it reached m.

4.4'-Isopropylidenediphenol 20 parts Polyvinyl alcohol (10% aqueous solution) 50 parts Water 30 parts The above composition was milled in a ball mill for 24 hours until the average particle size was 3μ.
A liquid B was obtained by pulverizing the mixture until it reached m.

Carbonate J Resium 20 parts Polyvinyl alcohol (10% aqueous solution) 60 parts Hydrin l-7 (Product name: Middle East Yushi Co., Ltd., zinc stearate)
20% dispersion liquid 20 parts The above navy blue composition was mixed with a dispersion machine, and C
I got the liquid.

After that, Δ solution: B solution: C solution: Water-1+2:2:3 ratio was mixed, and the resulting coating solution was applied to the coating film (first layer) surface obtained in (1) above after drying. After coating in such a manner that the coating m was equal to GO/Tri 'J', it was subjected to super main 11 rendering processing to obtain a heat-sensitive recording sheet with a Bekk smoothness of about 250 seconds.

Example 2 In Example 1, 1.3.5- was used instead of 1.1-bis(4-hydroxyphenyl)cyclohexane in the first layer coating liquid.
1-Lis(4-1-butyl-3-hydroxy-2,6-
Thermal recording sheets 1 to 1 were prepared in the same manner as in Example 1 using dimethyl) isocyanuric acid.

Example 3 In Example 1, 4,4'-thiobis(3-methyl-6-butylphenol) was used instead of the first layer coating liquid, and 4,4'-thiobis(3-methyl-6-butylphenol) was used in place of the coating liquid for the first layer, and 4,4'-thiobis(3-methyl-6-butylphenol) was used in , 4'-Isopropylidene diphenol was replaced with benzyl paraoxybenzoate, and the same procedure as in Example 1 was carried out to obtain a thermal recording sheet 1-.

Example 4 First layer coating liquid 4,4'-thiobi 9 in Example 3
A heat-sensitive recording sheet was obtained in the same manner as in Example 3 using benzyl rosebenzyloxybenzoate instead of 3-methyl-6-t-butylphenol.

Example 5 In Example 1, instead of using 10.9 parts of 1,1-bis(4-hydroxyphenyl)cyclohexane in the coating solution for the first layer, 5.5 parts of this material and 4,4'-thiobis(3 −
A thermosensitive recording sheet was obtained in the same manner as in Example 1 using 5.4 parts of methyl-6-t-butylphenol.

Example 6 In Example 1, 1.1-bis(4-
Instead of using 10.9 parts of 1.3.5-tris(4-1-butyl-3-hydroxyphenyl)cyclohexane,
Hydroxy-2,6-dimethyl)isocyanuric acid 5.5
A thermosensitive recording sheet was obtained in the same manner as in Example 1 using 5.4 parts of benzyl rosebenzyloxybenzoate.

Example 7 In Example 1, 310--N-mebru N-shik[-1hexylj'minnow〇-
3-di-n instead of methyl-7-aniritfur A゛ran
-butylamino-7-(2'-ri[11]anilino)
-C thermosensitive recording sheet 1- was obtained in the same manner as in τ Example 1 using fluoran.

Comparative example 1 In the same manner as in Example 1, 2nd hη river coating liquid Δ liquid and 13 liquid were applied.

Prepare liquid C, and without forming the first layer on the surface of the supporter (high-quality paper), apply the coating liquid for the first layer: Δ liquid: B liquid: C liquid - 3:1:2:2 A heat-sensitive recording sheet was obtained in the same manner as in Example 1, except that the coating liquid was mixed at the ratio of 7 and the coating liquid was applied.

Comparative Example 2 Same as Example 2, first skin coating liquid, liquid A, liquid B, C
Thermal recording sheet 1-111 was prepared in the same manner as in Comparative Example 1 except that the liquid was prepared.

Comparative Example 3 In the same manner as in Example 3, 4 waves for the first layer, liquid A, liquid B, and C were prepared.
Thermal recording sheets 1 to 1 were observed except for preparing the liquid (11 in the same manner as in Comparative Example 1).

11- Comparative Example 4 A thermosensitive recording sheet was obtained in the same manner as in Comparative Example 1, except that the first layer coating liquid, liquid A, liquid B, and liquid C were prepared in the same manner as in Example 4.

Comparative Example 5 A thermosensitive recording sheet was obtained in the same manner as in Comparative Example 1, except that the first layer coating liquid, liquid A, liquid B, and liquid C were prepared in the same manner as in Example 5.

Comparative Example 6 Heat-sensitive recording sheet 1 was prepared in the same manner as in Comparative Example 1, except that the first layer coating liquid, liquid A, liquid B, and liquid C were prepared in the same manner as in Example 6.
I got ~.

Comparative Example 7 Heat-sensitive recording sheet 1 was prepared in the same manner as in Comparative Example 1, except that the first layer coating liquid, liquid A, liquid B, and liquid C were prepared in the same manner as in Example 7.
I got ~.

Each heat-sensitive recording sheet obtained in the above Examples (including Comparative Examples) was transferred to a heat-sensitive facsimile K B-4800 (trade name, manufactured by Tokyo Shibaura Electric Co., Ltd.) at a normal head voltage (17,1
V), and the heat resistance, moisture resistance, and fingerprint resistance of the colored area and white area (uncolored area) were measured. The results are shown in the table below.

However, the values in the moisture resistance column in the table indicate the reflection density of the specimen before and after treatment. DM-27 for measurement
A Type 3 reflection densitometer (manufactured by Dainippon Screen Manufacturing Co., Ltd.) was used.

13- (table) (Additional note) "Processing" in the table means the processing shown below.

(1) Humidity resistance: 40℃, 2 specimens under 90χR1=1
When left for 4 hours.

14- (2) Heat resistance = When the specimen was left to dry at 60°C (constant temperature) for 24 hours.

(3) Evaluation of fingerprint resistance (based on visual sensation): This is the case where a fingerprint was placed on a sample and left in an open, normal humidity environment for 720 hours.

◎ Good, ○ Fair, Δ Slightly poor, X Poor As is clear from the above table, in each example, the coloring part.

Both the white parts have good moisture resistance, heat resistance, and fingerprint resistance, and in each comparative example, the moisture resistance, heat resistance, and fingerprint resistance of the colored parts are better than those of the materials in the examples. Yes, but
It is known that the corresponding physical properties in the white part are all inferior to those of the Examples.

15- Procedure nfli j'lE, jj, 4 (spontaneous) Il
6111F1, Special Correction Office, Kazuhito Sugi 1, Indication of the case 1982 (1 Patent Application No. 6, J't 856 No. 2, Name of the invention, Thermal Recording Sheet 3, Representative of the person making the amendment) Person: Yasushi Ochi Department 4, Agent 〒10!1 5. Attachment 1 of the notice of reasons for refusal (voluntary) 6. Subject of amendment ``Claims 11'' and ``Detailed description of the invention 1, column 7,'' Contents of the amendments Revised as shown in the attached sheet: First, the following amendments have been made to Mei 1lIII, submitted on April 4, 1982.

(1) The "Scope of Claims" on page 1 is corrected as follows.

[(1) In a heat-sensitive recording sheet in which a heat-sensitive color-forming layer is provided on a support, the heat-sensitive color-forming layer containing an acidic substance as a color developer for coloring a colorless or light-colored electron-donating color-forming substance when heated, the heat-sensitive color-forming layer and the support. between 1.1-bis(4-hydroxyphenyl)cyclohexane, 1.3.5-1~lis(4-1-butyl-3-hydroxy-2,6-dimethyl)isocyanuric acid, 4.4 1 or 2 of '-thiobis(3-methyl-6-t-butylphenol), benzyl rosebenzyloxybenzoate
A heat-sensitive recording sheet characterized by forming a layer containing at least seeds. (2) Page 6, lines 4-5 [Sand Grinder] 1- Correct the text to read "Sand Grinder."

(3) On page 15, line 9, correct the phrase ``...to endure,'' to ``...to endure,''.

that's all 2-

Claims (1)

[Claims] (1) A heat-sensitive recording sheet in which a heat-sensitive color-forming layer containing an acidic substance as a color developer for thermally developing a colorless or light-colored electron-donating 1'1 color-forming substance is disposed on a support; Between it and the support, 1.1-bis(4-hydroxyphenyl)cyclohexane, 1.3. .1 or 2 of 4'-thiobis(3-methyl-6-t-butylphenol) and benzyl parabenzyloxybenzoate
A heat-sensitive recording sheet characterized by forming a layer containing at least seeds.