JPH04220392A - Thermal recording material - Google Patents

Abstract

PURPOSE:To obtain a thermal recording material equipped sufficiently with functions such as chemical resistance and matching properties and also excellent in printability by adding an aqueous emulsion, which is 35dyn/cm or more in surface tension at the time of film-forming, into a protective layer. CONSTITUTION:0.1-2.0 pts.wt., preferably 0.5-1.0 pts.wt. of polyester, polyurethane, acrylic ester (co)polymer, styrene/acrylic copolymer, epoxy resin, polyvinyl acetate, polybiiridine chloride, polyvinyl chloride, derivatives of these substances, etc., are added to 1 pt.wt. of water-soluble resin so that the surface tension at the time of film-forming of a protective layer is 35dyn/cm or more. Under 0.1 pt.wt., an effect on printability is insufficient, and when 2.0 pts.wt. are exceeded, on the other hand, head matching properties, coloring properties, etc., are affected adversely. Thus, the obtained material is sufficiently equipped with functions such as chemical resistance and matching properties and also excellent in printability for ultraviolet-curing ink, flexographic ink, etc.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material, and more particularly to an improvement in a heat-sensitive recording material in which a heat-sensitive coloring layer that changes color when heated is provided on a support.

0002

[Prior Art] Heat-sensitive recording materials generally consist of a support such as paper, synthetic paper, or plastic film provided with a heat-sensitive coloring layer containing a heat-colorable composition as a main component. A colored image can be obtained by heating with a strobe lamp or the like. Compared to other recording materials, this type of recording material does not require complicated processing such as development and fixing, can produce records in a short time using relatively simple equipment, and generates less noise and pollutes the environment. Due to its advantages such as low cost, it is used for copying books, documents, etc.
It is widely used as a recording material in various fields such as electronic computers, facsimile machines, ticket vending machines, labels, and recorders. The thermochromic composition used in such heat-sensitive recording materials consists of a general coloring agent and a coloring agent that causes the coloring agent to develop color when heated. Examples of the coloring agent include a colorless material having a lactone, lactam, or spiropyran ring. Alternatively, light-colored leuco dyes have been used, and organic acids and phenolic substances have conventionally been used as color developers. A recording material made of a combination of a color forming agent and a color developing agent has the advantage that the obtained image has a particularly clear color tone, has a high background whiteness, and has excellent weather resistance. , is widely used.

[0003] However, this type of heat-sensitive recording material is
When it comes into contact with plasticizers such as OP, oils and fats, etc., it has the disadvantage that the image may be discolored or the background portion may develop color. In order to overcome these drawbacks, a protective layer has traditionally been provided on the heat-sensitive coloring layer, and the components that make up this protective layer include water-soluble resins such as polyvinyl alcohol and starch, and glyoxal and epoxy compounds. Fillers such as calcium carbonate and silica and waxes have been used as crosslinking agents to improve matching.

[0004] Heat-sensitive recording materials provided with such a protective layer can be used for food labels that are required to be resistant to plasticizers contained in edible oil and plastic wrap, etc., industrial labels that are required to be resistant to machine oil, etc. used in just,
Since these labels are often used after being printed with ultraviolet curable ink or flexo ink, it is necessary that the ink has good printability such as adhesiveness.

[0005]

However, in order to satisfy the above-mentioned functions such as chemical resistance and matching properties, the water-soluble polymers, fillers, waxes, etc. mentioned above are limited. As a result, it is difficult to obtain a heat-sensitive recording material that has sufficient quality and is also excellent in printability with ultraviolet curable inks, flexographic inks, and the like.

[0006] Accordingly, an object of the present invention is to provide a heat-sensitive recording material which is sufficiently equipped with functions such as chemical resistance and matching properties, and which is also excellent in printability with ultraviolet curable inks, flexo inks, etc. be.

[0007]

[Means for Solving the Problems] According to the present invention, in a heat-sensitive recording material comprising a heat-sensitive coloring layer that develops color by heating on a support and a protective layer on the heat-sensitive coloring layer, Provided is a heat-sensitive recording material characterized in that it is formed by adding an aqueous emulsion having a surface tension of 35 dyn/cm or more when filmed.

That is, the heat-sensitive recording material of the present invention has a heat-sensitive color-forming layer that develops color when heated on a support, and an aqueous emulsion having a surface tension of 35 dyn/cm or more at the time of film formation on the color-forming layer. This product has an added protective layer, and because of this structure, it has sufficient functions such as chemical resistance and matching properties, and is also suitable for printing with ultraviolet curable ink, flexographic ink, etc. It will also be excellent.

[0009] The heat-based coloring methods used in the present invention include those that utilize a coloring reaction between a leuco dye and a color developer, those that utilize a reaction between a diazo compound and a coupler, and those that utilize a reaction between an isocyanate and an amine. There are things to do. Since the feature of the present invention lies in the protective layer of the heat-sensitive recording material, the coloring method is not particularly limited. Hereinafter, a method using a general leuco dye will be explained as a heat-sensitive recording method.

[0010] In the present invention, as described above, an aqueous emulsion having a surface tension of 35 dyn/cm or more at the time of film formation is added to the protective layer, but the protective layer usually contains a water-soluble resin and a filler as main components. configured.

Materials for the aqueous emulsion added to the protective layer of the present invention include, for example, polyester, polyurethane, acrylic ester (co)polymer, styrene/acrylic copolymer, epoxy resin, polyvinyl acetate, and polychloride. Examples include vinylidene, polyvinyl chloride, and derivatives thereof. In addition, the amount added (based on the material) is 0.1 to 2.0 parts by weight per 1 part by weight of the water-soluble resin;
Preferably, 0.5 to 1.0 parts by weight is appropriate. If it is less than 0.1 parts by weight, the effect on printability will not be sufficient, and if it exceeds 2.0 parts by weight, the head matching performance,
It has a negative effect on color development, etc.

Examples of the water-soluble resin used in the protective layer of the present invention include polyvinyl alcohol, cellulose derivatives,
Starch and its derivatives, carboxyl group-modified polyvinyl alcohol, polyacrylic acid and its derivatives, styrene/
Acrylic acid copolymers and their derivatives, poly(meth)acrylamide and their derivatives, styrene/acrylic acid/acrylamide copolymers, amino group-modified polyvinyl alcohol, epoxy-modified polyvinyl alcohol, polyethyleneimine, isobutylene/maleic anhydride copolymers Examples include combinations and derivatives thereof.

Fillers used in the protective layer of the present invention include, for example, calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, and surface-treated calcium. In addition to inorganic fine powders such as silica and silica, organic fine powders such as urea-formalin resin, styrene/methacrylic acid copolymer, and polystyrene resin can be mentioned.

[0014] The protective layer of the present invention may optionally contain a crosslinking agent for improving water resistance, chemical resistance, etc., a lubricant for improving the slippage of the head, etc. can be added.

[0015] In the present invention, the leuco dyes used in the thermosensitive coloring layer may be applied singly or in combination of two or more.
As such leuco dyes, those applied to this type of heat-sensitive material may be arbitrarily applied, such as triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, spiropyran-based, indolinophthalide-based, etc. Leuco compounds of dyes are preferably used. Specific examples of such leuco dyes include those shown below.

3,3-bis(p-dimethylaminophenyl)-phthalide, 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (also known as crystal violet lactone), 3,3-bis( p-dimethylaminophenyl)-6-diethylaminophthalide, 3
, 3-bis(p-dimethylaminophenyl)-6-chlorophthalide, 3,3-bis(p-dibutylaminophenyl)phthalide, 3-cyclohexylamino-6-chlorofluoran, 3-dimethylamino-5,7- Dimethylfluorane, 3-N-methyl-N-isobutyl-6-methyl-7-anilinofluorane, 3-N-ethyl-N-isoamyl-6-methyl-7-anilinofluorane, 3-
Diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-
7,8-benzfluorane, 3-diethylamino-6-
Methyl-7-chlorofluorane, 3-(N-p-tolyl-N-ethylamino)-6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 2 -{N-(3'-trifluoromethylphenyl)amino}-6-diethylaminofluorane, 2-
{3,6-bis(diethylamino)-9-(o-chloroanilino)xanthylbenzoic acid lactam}, 3-diethylamino-6-methyl-7-(m-trichloromethylanilino)fluoran, 3-diethylamino-7-( o-
chloroanilino)fluoran, 3-di-n-butylamino-7-(o-chloroanilino)fluoran, 3-N-
Methyl-N,n-amylamino-6-methyl-7-anilinofluorane, 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7 −anilinofluorane,
3-diethylamino-6-methyl-7-(2',4'-
dimethylanilino)fluoran, 3-(N,N-diethylamino)-5-methyl-7-(N,N-dibenzylamino)fluoran, benzoylleucomethylene blue,
6'-chloro-8'-methoxy-benzoindolino-spiropyran, 6'-bromo-3'-methoxy-benzoindolino-spiropyran, 3-(2'-hydroxy-4
'-Dimethylaminophenyl)-3-(2'-methoxy-5'-chlorophenyl)phthalide, 3-(2'-hydroxy-4'-dimethylaminophenyl)-3-(2'
-methoxy-5'-nitrophenyl)phthalide, 3-(
2'-hydroxy-4'-diethylaminophenyl)-
3-(2'-methoxy-5'-methylphenyl)phthalide, 3-(2'-methoxy-4'-dimethylaminophenyl)-3-(2'-hydroxy-4'-chloro-5'
-methylphenyl)phthalide, 3-morpholino-7-(
N-propyl-trifluoromethylanilino)fluoran, 3-pyrrolidino-7-trifluoromethylanilinofluoran, 3-diethylamino-5-chloro-7-(
N-benzyl-trifluoromethylanilino)fluorane, 3-pyrrolidino-7-(di-p-chlorophenyl)
Methylaminofluoran, 3-diethylamino-5-chloro-7-(α-phenylethylamino)fluoran,
3-(N-ethyl-p-toluidino)-7-(α-phenylethylamino)fluoran, 3-diethylamino-
7-(o-methoxycarbonylphenylamino)fluoran, 3-diethylamino-5-methyl-7-(α-phenylethylamino)fluoran, 3-diethylamino-7-piperidinofluorane, 2-chloro-3-( N-
methyltoluidino)-7-(p-n-butylanilino)
Fluoran, 3-(N-methyl-N-isopropylamino)-6-methyl-7-anilinofluoran, 3-di-
n-Butylamino-6-methyl-7-anilinofluorane, 3,6-bis(dimethylamino)fluorenespiro(9,3')-6'-dimethylaminophthalide, 3-(
N-benzyl-N-cyclohexylamino)-5,6-
Benzo-7-α-naphthylamino-4'-bromofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3-N-ethyl-N-(2-ethoxypropyl)amino-6-methyl -7-anilinofluorane,
3-N-ethyl-N-tetrahydrofurfurylamino-
6-Methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-mesitidino-4', 5'-benzofluorane, 3-N-ethyl-N-isobutyl-6-
Methyl-7-anilinofluorane, etc.

The color developer used in the heat-sensitive coloring layer of the present invention may include various electron-accepting compounds that cause the leuco dye to develop color upon contact, such as phenolic compounds, thiophenolic compounds, thiourea derivatives, organic Acids and their metal salts are preferably used, and specific examples include those shown below.

4,4'-isopropylidene bisphenol, 4,4'-isopropylidene bis(o-methylphenol), 4,4'-secondary butylidene bisphenol 4,4'-isopropylidene bis(2-tert-butylphenol) ), 4,4'-cyclohexylidene diphenol, 4,4'-isopropylidene bis(2
-chlorophenol), 2,2'-methylenebis(4-
methyl-6-tert-butylphenol), 2,2
'-methylenebis(4-ethyl-6-tert-butylphenol), 4,4'-butylidenebis(6-tert-butyl-2-methylphenol), 1,1,3
-Tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,1,3-tris(2-
Methyl-4-hydroxy-5-cyclohexylphenyl)butane, 4,4'-thiobis(6-tert-butyl-2-methylphenol), 4,4'-diphenolsulfone, 4-isopropoxy-4'-hydroxy Diphenylsulfone, 4-benzyloxy-4'-hydroxydiphenylsulfone, 4,4'-diphenolsulfoxide, isopropyl P-hydroxybenzoate, benzyl P-hydroxybenzoate, benzyl protocatechuate, stearyl gallate, lauryl gallate, Octyl gallate, 1,7-bis(4-hydroxyphenylthio)
-3,5-dioxaheptane, 1,5-bis(4-hydroxyphenylthio)-3-oxapentane, 1,3-
Bis(4-hydroxyphenylthio)-propane, 1,
3-bis(4-hydroxyphenylthio)-2-hydroxypropane, N,N'-diphenylthiourea, N,N
'-di(m-chlorophenyl)thiourea, salicylanilide, 5-chloro-salicylanilide, 2-hydroxy-3-naphthoic acid, 2-hydroxy-1-naphthoic acid,
1-Hydroxy-2-naphthoic acid, metal salts of hydroxynaphthoic acid such as zinc, aluminum, calcium, etc., bis-(4-hydroxyphenyl)acetic acid methyl ester, bis-(4-hydroxyphenyl)acetic acid benzyl ester, 1,3 -bis(4-hydroxycumyl)benzene, 1
, 4-bis(4-hydroxycumyl)benzene, 2,4
'-diphenolsulfone, 3,3'-diallyl-4,
4'-diphenolsulfone, α,α-bis(4-hydroxyphenyl)-α-methyltoluene, antipyrine complex of zinc thiocyanate, tetrabromobisphenol A, tetrabromobisphenol S, etc.

In order to produce the heat-sensitive recording material of the present invention,
When a leuco dye and a color developer are bonded and supported on a support, various commonly used binders can be used as appropriate, and specific examples include the following.

Polyvinyl alcohol, starch and its derivatives, cellulose derivatives such as hydroxymethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, polyacrylic acid source DA, polyvinylpyrrolidone, acrylamide/acrylic acid ester copolymer, acrylamide/acrylic acid ester/methacrylic acid terpolymer, styrene/maleic anhydride copolymer alkali salt, isobutylene/maleic anhydride copolymer alkali salt, In addition to water-soluble polymers such as polyacrylamide, sodium alginate, gelatin, and casein, polyvinyl acetate, polyurethane, polyacrylic acid, polyacrylic ester, vinyl chloride/vinyl acetate copolymer, and polybutyl methacrylate , emulsions such as ethylene/vinyl acetate copolymers, latexes such as styrene/butadiene copolymers, styrene/butadiene/acrylic copolymers, etc.

[0021] In addition to the leuco dye and color developer, the thermosensitive coloring layer of the present invention may also contain, if necessary, auxiliary additive components commonly used in this type of heat-sensitive recording material, such as fillers, surfactants, and heat-sensitive recording materials. A fusible substance (or lubricant), pressure coloring inhibitor, etc. can be used in combination. In this case, specific examples of the filler include the same fillers as those exemplified in relation to the protective layer. Examples of thermofusible substances include higher fatty acids or their esters, amides, or metal salts, various waxes, condensates of aromatic carboxylic acids and amines, benzoic acid phenyl esters,
Examples include higher linear glycols, dialkyl 3,4-epoxy-hexahydrophthalates, higher ketones, p-benzene biphenyl, and other thermofusible organic compounds having a melting point of about 50 to 200°C.

In the present invention, an undercoat layer may be provided between the support and the heat-sensitive coloring layer, if necessary. In this case, the above-mentioned filler, binder, thermofusible substance, surfactant, etc. can be used as components constituting the undercoat layer.

The heat-sensitive recording material of the present invention can be used in various fields, but in particular, by taking advantage of its excellent printability, it can be used as a heat-sensitive recording label sheet that requires printing and a heat-sensitive recording magnetic ticket paper. It can be used to advantage. In the case of a heat-sensitive recording type label sheet, a heat-sensitive coloring layer containing the above-mentioned leuco dye and color developer and the above-mentioned protective layer are provided on one side of the support, and an adhesive layer is provided on the other side of the support. In the case of magnetic ticket paper, a magnetic recording layer containing a ferromagnetic material and a binder as main components may be provided in place of the release mount.

[0024]

EXAMPLES The present invention will now be explained in more detail by way of examples. Note that all parts and percentages below are based on weight.

First, mixtures having the following compositions were ground and dispersed using a sand grinder for 2 to 4 hours to prepare [Liquid A] and [Liquid B].

[Liquid A] 3-(N-methyl-N-cyclohexyl)amino-6-
10 parts Methyl-7-anilinofluorane
10% aqueous solution of polyvinyl alcohol
10
Part water

80 copies

[Liquid B] Benzyl p-hydroxybenzoate

10 parts calcium carbonate

10 parts 2,2'-methylenebis(4-methyl-6-tert-butylphenol) 5 parts Polyvinyl alcohol 1
0% aqueous solution
20 parts water


55 copies

[0028] Further, [Liquid A] and [Liquid B] were mixed and stirred at a weight ratio of 1:3 to prepare a heat-sensitive coloring layer coating solution, and coated on commercially available high quality paper after drying, the coating amount was 5.4 to 5.4. 5.6g/
The paper coated with the heat-sensitive coloring layer was obtained by coating with a lab coating rod and drying the coating to a thickness of m2.

Separately, aqueous emulsions shown in Table 1 were prepared.

[0030]

[Table 1]

[0031] Implementation 1 [Liquid C] was prepared by stirring and dispersing a mixture having the following composition.

[Liquid C] Acrylic acid ester emulsion-1 (solid content 10%) 25.0 parts 10% aqueous solution of polyvinyl alcohol
50.0 parts calcium carbonate
2.
5 parts Zinc stearate

0.2 parts water

22
．． Part 3

Next, a polyamide-epichlorohydrin copolymer was added to [Liquid C] at a solid content of 0.4 part per 1 part of polyvinyl alcohol in [Liquid C] to prepare a protective layer solution. did.

The obtained protective layer solution was applied onto the paper coated with the thermosensitive coloring layer so as to have a dry weight of 5 g/m 2 , and dried, followed by calendering to obtain the thermosensitive recording material of the present invention.

Example 2 In Example 1, except that polyurethane emulsion-2 (solid content 10%) was used instead of acrylic acid ester emulsion-1 (solid content 10%) in [Liquid C], A heat-sensitive recording material of the present invention was obtained in the same manner as in Example 1.

Comparative Example 1 A comparative heat-sensitive recording material was obtained in the same manner as in Example 1, except that acrylic acid ester emulsion-1 (solid content 10%) in [liquid C] in Example 1 was excluded. Ta.

Comparative Example 2 Except for using acrylic ester emulsion-2 (solid content 10%) instead of acrylic ester emulsion-1 (solid content 10%) in [Liquid C] in Example 1. A comparative heat-sensitive recording material was obtained in the same manner as in Example 1.

Comparative Example 3 Example 1 except that polyurethane emulsion-2 (solid content 10%) was used instead of acrylic ester emulsion-1 (solid content 10%) in [liquid C]. A comparative heat-sensitive recording material was obtained in the same manner as in Example 1.

The heat-sensitive recording material obtained as described above was tested using an ultraviolet irradiation printing tester (manufactured by Mei Seisakusho; RI-2).
A printability test was conducted. The inks used are an ultraviolet irradiation type blue ink (manufactured by Dainippon Ink Co., Ltd.) and an ultraviolet ray irradiation type vanish ink (manufactured by Dainippon Ink Co., Ltd.; DIC OP varnish), the amount used is 1 cc, and the kneading time is 2 minutes. The results are shown in Table 2. Note that the density value of the blue ink is the result of measurement using a Macbeth densitometer RD914 model and a red filter. In addition, the glossiness value of the vanish ink was determined using a gloss meter 1001DP manufactured by Nippon Denshoku Co., Ltd. at an illumination angle of 7.
These are the measurement results at 5°.

[0040]

[Table 2]

As is clear from Table 2, it can be seen that the heat-sensitive recording material of the present invention has better printability than the conventional one.

[0042]

As explained above, in the heat-sensitive recording material of the present invention, an aqueous emulsion having a surface tension of 35 dyn/cm or more at the time of film formation is added to the protective layer provided on the heat-sensitive coloring layer. Because of this structure, it not only has sufficient functions such as chemical resistance and matching properties, but also has improved suitability for printing with ultraviolet curable inks, flexographic inks, etc. compared to conventional heat-sensitive recording materials. .

Claims (2)

[Claims] Claim 1: A heat-sensitive recording material comprising a heat-sensitive coloring layer that develops color upon heating on a support, and a protective layer provided on the heat-sensitive coloring layer, wherein the protective layer has a surface tension of 35 dyn/dyn during film formation.
1. A heat-sensitive recording material, characterized in that it is made by adding an aqueous emulsion having a water-based emulsion of at least cm. 2. The heat-sensitive recording material according to claim 1, wherein the aqueous emulsion is an acrylic ester emulsion or a polyurethane emulsion.