JP3254502B2 - Thermal recording material - Google Patents

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 having a support provided with a heat-sensitive coloring layer which is colored by heat.

[0002]

2. Description of the Related Art A thermosensitive recording material generally comprises a support such as paper, synthetic paper, plastic film and the like, on which a thermosensitive coloring layer mainly composed of a thermochromic composition is provided. A colored image can be obtained by heating with light or a strobe lamp. Compared to other recording materials, this type of recording material can record in a short time with a relatively simple device without performing complicated processing such as development and fixing, and generates less noise and environmental pollution. In addition to its advantages such as lower cost, it is used for copying books and documents, as well as electronic calculators, facsimile machines, ticket vending machines,
It is widely used as a recording material in various fields such as labels and recorders. The thermochromic composition used in such a thermosensitive recording material is composed of a normal color former and a developer that causes the color former to develop color when heated, and has, for example, a lactone, lactam or spiropyran ring as the color former. A colorless or light-colored leuco dye has been used, and an organic acid or a phenolic substance has been used as a developer. The recording material in which the color former and the developer are combined has the advantages that the obtained image has a particularly vivid color tone, a high whiteness of the background, and excellent weather resistance of the image. , Widely used.

However, this kind of thermal recording material is DO
When it comes in contact with plasticizers such as A (dioctyl adipate) and DOP (dioctyl phthalate) or oils and fats, the image is erased or the background is colored by solvents such as ethanol and ethyl acetate. However, there is a defect that the reliability is poor, and as a method for improving these, it has been proposed to provide an overcoat layer (protective layer) on the heat-sensitive layer (Japanese Patent Application Laid-Open Nos. 54-128347 and 54-3594). Gazettes). These overcoat layers are mainly composed of a resin and a cross-linking agent for curing the resin, and various cross-linking agents have been proposed to impart water resistance particularly for preventing the overcoat layer from being peeled off by water. However, even if it is excellent in reactivity, the background coloring (dark area in the non-printed area), the temporal stability of the overcoat layer coating solution is impaired, the matching property with the print head of the printer is poor, and There is a problem that the print image is blurred due to the adhesion of the ink and the print head is damaged, and it has not been solved yet.

[0004] Further, for the purpose of eliminating unevenness of the support or increasing the sensitivity by preventing heat energy during printing from being lost, an underlayer is provided between the support and the heat-sensitive recording layer, or a print head during printing is provided. There is also a back coat layer provided to prevent the runnability of the plastic material from penetrating from the back surface and sticking (blocking) between the heat-sensitive materials when the roll material is formed, but the undercoat layer and the back coat layer Each of them mainly comprises a resin and a cross-linking agent, and requires improvement in water resistance similarly to the overcoat layer. Many cross-linking agents have also been proposed. Among such crosslinking agents,
Polyamide epichlorohydrin-based cross-linking agents which are hardened and have particularly good water resistance and also have a relatively well-balanced quality required for other heat-sensitive recording papers are disclosed in JP-A-60-244596 and JP-A-60-244596. 61-112
No. 88). However, the polyamide epichlorohydrin-based crosslinker contains a low molecular weight organic chlorine compound due to a problem in production, and when used as a curing agent for a resin, the low molecular weight organic chlorine compound reacts with the resin to form a high molecular weight organic chlorine compound. Since the curing reaction with the resin is hindered, the plasticizer resistance of the heat-sensitive layer is reduced, and the low-molecular-weight organochlorine compound and the reactant become scum during printing, adhere to the print head, and cause blurring of the printed image. Further, the amount of the organochlorine compound in the heat-sensitive recording material is unnecessarily increased, which causes dot breakage due to breakage of the print head, that is, causes so-called head electrolytic corrosion. (Organic chlorine compounds cause head electrolytic corrosion. Is well known). As described above, at present, the polyamide epichlorohydrin-based cross-linking agent still has many insufficient points.

[0005]

SUMMARY OF THE INVENTION The present invention provides an improved polyamide epichlorohydrin cross-linking agent which is excellent in water resistance and plasticizer resistance, has good head matching properties, and causes damage to a heat-sensitive head due to electrolytic corrosion. The aim is to provide a heat-sensitive recording material.

[0006]

According to the present invention, in a heat-sensitive recording material provided with a heat-sensitive coloring layer which is colored by heat on a support, an overcoat mainly comprising a resin and a crosslinking agent is provided on the heat-sensitive coloring layer. A heat-sensitive recording material is provided, in which a coating layer is provided, and a polyamide epichlorohydrin resin having a content of a low molecular weight organic chlorine compound of 1% by weight or less is used as the crosslinking agent. Further, according to the present invention, in a heat-sensitive recording material provided with a heat-sensitive coloring layer colored by heat on a support , an undercoat layer mainly composed of a resin and a crosslinking agent is provided between the support and the heat-sensitive coloring layer. A thermosensitive recording material is provided, wherein a polyamide epichlorohydrin resin having a content of a low molecular weight organic chlorine compound of 1% by weight or less is used as the crosslinking agent. Further, according to the present invention, in a heat-sensitive recording material provided with a heat-sensitive color-forming layer colored by heat on a support, a back coat layer mainly composed of a resin and a cross-linking agent is provided on the back of the support, and the cross-linking agent is provided. A thermosensitive recording material characterized by using a polyamide epichlorohydrin resin having a content of a low molecular weight organic chlorine compound of 1% by weight or less.

According to the present invention, there is provided a thermosensitive recording medium provided with a thermosensitive coloring layer on a support, wherein an overcoat layer is provided on the thermosensitive coloring layer, or an undercoat layer is provided between the support and the thermosensitive coloring layer; A back coat layer is provided on the back surface of the support, and a low molecular weight organochlorine compound of a polyamide epichlorohydrin resin is reduced as a cross-linking agent in each of the overcoat layer, the undercoat layer and the back coat layer, and the low cross-linking agent resin component is reduced. By controlling the content of the molecular organic chlorine compound to 1% by weight or less, a heat-sensitive recording material having good head matching properties, low head electrolytic corrosion properties, and excellent plasticizer resistance and water resistance can be obtained.

Next, a detailed description will be given of the electrolytic corrosion of the head when the polyamide epichlorohydrin resin according to the present invention is used as a crosslinking agent. The effect of suppressing the electrolytic corrosion of the head by the cross-linking agent of the present invention is greatest when the cross-linking agent is used in the overcoat layer, but is also effective when used in the undercoat layer or the backcoat layer. The undercoat layer containing the crosslinking agent of the present invention is provided on an undercoat layer or a backcoat layer using a conventional amide epichlorohydrin resin containing a low-molecular-weight organic chlorine compound as a crosslinking agent. When the cross-linking agent of the present invention is used as the cross-linking agent of the back coat layer and an overcoat layer containing the cross-linking agent of the present invention is further provided, the effect of suppressing the electrolytic corrosion of the head is improved.

Further, when a conventional crosslinker of an amide epichlorohydrin resin containing a low molecular weight organic chlorine compound is used in the overcoat layer and the crosslinker of the present invention is used in the undercoat layer or the backcoat layer, The effect of the organochlorine compound in the overcoat layer, which is the contact portion of the thermal head, is large. Even if the crosslinking agent of the present invention is used for the undercoat layer and the backcoat layer, the effect is not so high, but the water resistance and the plastic resistance are high. With respect to the agent properties, those which are superior to the conventional undercoat layer and backcoat layer using a polyamide epichlorohydrin crosslinking agent can be obtained.

In the present invention, the addition amount of the crosslinking agent is 0.1 to 1 part by weight with respect to 1 part by weight of the resin, from the viewpoint of low head corrosion resistance, plasticizer resistance and water resistance. But more preferably 0.3 to 0.51 part by weight. In the present invention, a crosslinking agent such as boric acid, epoxy, aziridine, glycidylamine, glyoxal, or a compound containing a methylol group, which is conventionally used, can be used together with the crosslinking agent.

The resins that can be used in the present invention include generally used resins such as polyvinyl alcohol, cellulose derivatives, starch and derivatives thereof, carboxyl group-modified polyvinyl alcohol, polyacrylic acid and derivatives thereof, and styrene / acrylic. Acid copolymers and derivatives thereof, poly (meth) acrylamide and derivatives thereof, styrene / acrylic acid / acrylamide copolymers, amino group-modified polyvinyl alcohol, epoxy-modified polyvinyl alcohol, polyethylene imine, aqueous polyester, aqueous polyurethane, isobutylene / Maleic anhydride copolymers and derivatives thereof, polyesters,
Examples include polyurethane, acrylic ester (co) polymer, styrene / acrylic copolymer, epoxy resin, polyvinyl acetate, polyvinylidene chloride, polyvinyl chloride, and derivatives thereof. Although the above resins are not particularly limited, water-soluble resins are particularly preferable in consideration of chemical resistance.

In the overcoat layer according to the present invention, in addition to the above-mentioned resin / crosslinking agent, conventionally used auxiliary additives such as a filler, a surfactant, and a heat-fusible substance (or Lubricating agent), a pressure coloring inhibitor, and the like. In this case, examples of the filler include inorganic fine powders such as calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, and surface-treated calcium and silica. Organic fine powders such as urea-formalin resin, styrene / methacrylic acid copolymer, and polystyrene resin. Examples of the heat-fusible substance include, in addition to 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, Examples thereof include dialkyl 4-epoxy-hexahydrophthalate, higher ketones, p-benzylbiphenyl and other heat-fusible organic compounds having a melting point of about 50 to 200 ° C.

As a method of coloring by heat according to the present invention,
There are those utilizing a color development reaction between a leuco dye and a developer, those utilizing a reaction between a diazo compound and a coupler, and those utilizing a reaction between an isocyanate and an amine. In the present invention, the coloring method is not particularly limited, but here, a method using a general leuco dye will be described. The leuco dyes used in the present invention are applied alone or as a mixture of two or more kinds. As such leuco dyes, those applied to this kind of heat-sensitive material are arbitrarily applied. And fluoran-based, phenothiazine-based, auramine-based, spiropyran-based and indolinophthalide-based leuco compounds are preferably used. Specific examples of such leuco dyes include, for example, 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-dimethylaminophenyl) phthalide, p-cyclohexialamino-6-chlorofluoran, p-dimethylamino-5 7-dimethylfluoran, 3-diethylamino-7-chlorofluoran, 3-diethylamino-7-methylfluoran, 3
-Diethylamino-7,8-benzfluoran, 3-diethylamino-6-methyl-7-chlorofluoran, 3
-(Np-tolyl-N-ethylamino) -6-methyl-7-anilinofluoran, 3-pyrrolidino-6-methyl-7-anilinofluoran, 2- {N- (3'-trifluoro) L-methylphenyl) amino} -6-diethylaminofluoran, 2- {3,6-bis (diethylamino)
-9- (o-Chloranilino) xanthylbenzoic acid lactam}, 3-diethylamino-6-methyl-7- (m-
Trichloromethylanilino) fluoran, 3-dibutylamino-7- (o-chloroanilino) fluoran, 3-
N-methyl-N-amylamino-6-methyl-7-anilinofluoran, 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7 -Anilinofluoran,
3- (N, N-diethylamino) -5-methyl-7-
(N, N-dibenzylamino) fluoran, benzoylleucomethylene blue, 6'-chloro-8'-methoxy-benzoindolino-pyrrolospirane, 6'-bromo-
3′-methoxy-benzoindolino-pyrrospirane,
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-diethylemino-5-chloro-7- (N-benzyl-trifluoromethylanilino) fluoran, 3-pyrrolidino-7
-(Di-p-chlorophenyl) methylanilinofluoran, 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-piperidinofluoran, 2-chloro-3- (N-methyltoluidino)-
7- (pn-butylanilino) fluoran, 3- (N
-Benzyl-N-cyclohexylamino) -5,6-benzo-7-α-naphthylamino-4′-bromofluorane, 3-diethylamino-6-methyl-7-mesitidino-4 ′, 5′-benzofluoran , 3-Diethylemino-6-methyl-7- (2 ', 4'-dimethylanilino)
Fluoran,

As the color developer used in the present invention, various electron-accepting compounds capable of forming a color when the leuco dye is brought into contact, for example, phenolic compounds, thiophenolic compounds, thiourea derivatives, organic acids and their metals Salts and the like are preferably applied, and specific examples thereof include the following.

4,4'-isopropylidenebisphenol, 4,4'-isopropylidenebis (o-methylphenol), 4,4'-secondarybutylidenebisphenol, 4,4'-isopropylidenebis (o-tertiary) Butylphenol), 2,2′-methylenebis (4-methyl-6-tert-butylphenol),
2,2′-methylenebis (4-ethyl-6-tert-butylphenol), 4,4′-butylidenebis (6
-Tert-butyl-2-methyl) phenol, 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-methyl) phenol, 4,4'-diphenolsulfone, 4,2'-diphenolsulfone,
4-Isopropoxy-4′-hydroxydiphenylsphone, 4-benzyloxy-4′-hydroxydiphenylsphone, 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, 2, 2'-methylenebis (4-ethyl-6-tert-butylphenol),
1,3-bis (4-hydroxyphenylthio) -2-hydroxypropane, N, N′-diphenylthiourea,
N, N'-di (m-chlorophenyl) thiourea, salicylanilide, 5-chloro-salicylanilide, salicyl-o-chloroanilide, 2-hydroxy-3-naphthoic acid, antipyrine complex of zinc thiocyanate, 2-acetyl Zinc salt of oxy-3-naphthoic acid, 2-hydroxy-
1-naphthoic acid, 1-hydroxy-2-naphthoic acid, metal salts of hydroxynaphthoic acid such as zinc, aluminum and calcium, methyl bis- (4-hydroxyphenyl) acetate, and benzyl bis- (4-hydroxyphenyl) acetate Esters, 1,3-bis (4-hydroxyphenyl) benzene, 1,4-bis (4-hydroxyphenyl) benzene, 2,4′-diphenolsulfone,
3,3′-diallyl-4,4′-diphenol sulfone, α, α-bis (4-hydroxyphenyl) -α-methyltoluene, an antipyrine complex of zinc thiocyanate,
Tetrabromobisphenol S and the like.

In the present invention, various conventional binders can be used for binding and supporting the leuco dye, the developer and the auxiliary components on a support. For example, polyvinyl alcohol, starch and derivatives thereof, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, cellulose derivatives such as ethylcellulose, sodium polyacrylate, polyvinylhyrolidone, acrylamide / acrylate copolymer, acrylamide / acrylate Water-soluble polymers such as terpolymer / methacrylic acid terpolymer, alkali salt of styrene / maleic anhydride copolymer, alkali salt of isobutylene / maleic anhydride copolymer, polyacrylamide, sodium alginate, gelatin, casein, etc. Vinyl acetate, polyurethane, polyacrylate,
Emulsions such as polymethacrylic acid esters and ethylene / vinyl acetate copolymers and latexes such as styrene / butadiene copolymers and styrene / butadiene / acrylic copolymers are mentioned, but those containing chlorine are particularly avoided. Should.

In the present invention, the leuco dye, the color developing agent and the auxiliary component may be used, if necessary, together with auxiliary additive components commonly used in this type of heat-sensitive recording material, such as fillers and surfactants. can do. In this case, as the filler, for example, calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, surface-treated inorganic fine powder such as calcium and silica, Examples include organic fine powders such as urea-formalin resin, styrene / methacrylic acid copolymer, and polystyrene.
The heat-sensitive recording material of the present invention is used in various fields. In particular, the heat-sensitive recording material is used as a heat-sensitive recording label sheet or a heat-sensitive recording magnetic ticket paper, utilizing the above-described excellent color image and stability of the background portion. It can be used advantageously. In the case of a heat-sensitive recording type label sheet, a heat-sensitive coloring layer containing the leuco dye and a developer described above is provided on one surface of the support and a protective layer, and a release sheet is provided on the other surface of the support via an adhesive layer. In the case of magnetic ticket paper, instead of this release liner,
What is necessary is just to provide a magnetic recording layer containing a ferromagnetic material and a binder as main components.

[0019]

(Formation of thermosensitive coloring layer)

(Solution A) 3- (N-cyclohexyl-N-methyl) amino-6-methyl-7-anilinofluoran 10 parts 10% hydroxyethylcellulose aqueous solution 20 parts Water 60 parts (Solution B) 10 parts Bisphenol A 5 parts Carbonic acid Calcium 5 parts Stearic acid amide 20 parts 10% aqueous polyvinyl alcohol solution 60 parts Water The above solution A and solution B are each dispersed by a sand mill so that the average particle diameter becomes 2 μm or less. One part of the liquid A, 8 parts of the liquid B and 1 part of a 10% aqueous polyvinyl alcohol solution thus obtained are mixed and stirred to obtain a thermosensitive coloring layer coating liquid. This coating solution is applied on a commercially available high-quality paper having a basis weight of 52 g / m ² or an undercoat layer provided on the high-quality paper so as to have a dry adhesion amount of 6 g / m ² and dried to form a thermosensitive coloring layer. I do. [Formation of Undercoat Layer] (Liquid C) Kaolin 10 parts 10% aqueous solution of polyvinyl alcohol 1 part Water 89 parts The above liquid C is dispersed by a sand mill so that the average particle diameter becomes 2 μm or less. (Solution D) Solution C 50 parts 10% carboxyl-modified polyvinyl alcohol aqueous solution 10 parts Polyamide epichlorohydrin treated to have an organochlorine compound content as shown in the preparation method of the thermosensitive recording material of each of Examples and Comparative Examples Resin cross-linking agent and its substitute (solids concentration 10%) 1 part Water 39 parts The above-mentioned liquid D was applied on a commercially available high-quality paper having a basis weight of 52 g / m ^{2 so} that the dry adhesion amount was 6 g / m ² and dried. To form an undercoat layer. [Formation of Overcoat Layer] (Solution E) 40 parts of liquid C 40 parts of 10% aqueous solution of polyvinyl alcohol 40 parts of an organic chlorine compound as shown in the preparation method of the thermosensitive recording material of each of Examples and Comparative Examples. Treated polyamide epichlorohydrin resin cross-linking agent and its substitute (solid content concentration 10%) 4 parts Zinc stearate (30%) 2 parts Water 12 parts The above E solution has a dry adhesion amount of 3.6 g / m ² . As described above. [Formation of Backcoat Layer] (Solution F) Solution C 30 parts 10% aqueous solution of polyvinyl alcohol 40 parts The content of the organic chlorine compound as shown in the method for preparing the thermosensitive recording material of each of Examples and Comparative Examples was adjusted. 4 parts of the treated polyamide epichlorohydrin resin crosslinking agent and its substitute (solid content concentration: 10%) 4 parts of the above solution F is applied to the back surface of the support so that the dry adhesion amount becomes 3 g / m ² to obtain a back coat layer .

Example 1 A heat-sensitive layer was directly provided on a support by the above-mentioned method using the heat-sensitive coloring layer coating solution obtained from Solution A, Solution B or the like. A low molecular weight organic chlorine compound in the polyamide epichlorohydrin resin crosslinker was treated thereon, and the above-mentioned E using a crosslinker in which the content of the low molecular weight organic chlorine compound in the crosslinker was 0.3% was used.
Using the liquid, a heat-sensitive recording material of Example 1 having an overcoat layer was prepared.

Example 2 In Example 1, instead of the crosslinking agent having a low-molecular-weight organic chlorine compound content of 0.3% as the crosslinking agent, a crosslinking agent having a low-molecular-weight organic chlorine compound content of 0.6% was used. In the same manner as in Example 1 except that the heat-sensitive recording material of Example 2 having an overcoat layer was used.

Use [0022] In Comparative Example 1 Example 1, in place of the low content of molecules organochlorine compound 0.3% crosslinking agent as a crosslinking agent, the content of low-molecular organic chlorine compound is 12% of a crosslinking agent Comparative Example 1 having an overcoat layer in the same manner as in Example 1 except for
Was prepared.

[0023] use in Comparative Example 2 Example 1, in place of the low content of molecules organochlorine compound 0.3% crosslinking agent as a crosslinking agent, the content of low-molecular organic chlorine compound is 24% of a crosslinking agent Comparative Example 2 having an overcoat layer in the same manner as in Example 1 except for
Was prepared.

Comparative Example 3 In the same manner as in Example 1, except that a crosslinking agent of a methylol resin was used in place of the crosslinking agent having a low-molecular-weight organic chlorine compound content of 0.3% as the crosslinking agent. Thus, a heat-sensitive recording material of Comparative Example 3 having an overcoat layer was prepared.

[0025] On Example 3 support processes the low-molecular organic chlorine compounds polyamide epichlorohydrin resin crosslinking agent in a low amount in the crosslinker
An undercoat layer was formed using the above-mentioned liquid C using a crosslinking agent having a content of the organic chlorine compound of 0.3%. A heat-sensitive layer was provided thereon by the above-mentioned method using the above-mentioned heat-sensitive color-forming layer coating solution obtained from Solution A, Solution B, etc., to prepare a heat-sensitive recording material of Example 3 having an undercoat layer.

Use [0026] In Comparative Example 4 Example 3, in place of the low content of molecules organochlorine compound 0.3% crosslinking agent as a crosslinking agent, the content of low-molecular organic chlorine compound is 12% of a crosslinking agent Comparative Example 4 having an undercoat layer in the same manner as in Example 3 except that
Was prepared.

Comparative Example 5 In the same manner as in Example 3, except that a crosslinking agent of a methylol-based resin was used instead of the crosslinking agent having a low-molecular-weight organic chlorine compound content of 0.3% as the crosslinking agent. Thus, a heat-sensitive recording material of Comparative Example 5 having an undercoat layer was prepared.

Example 4 A heat-sensitive layer was directly provided on a support by the method described above using the heat-sensitive color-forming layer coating solution obtained from Solution A, Solution B or the like. On the back surface of the support provided with the heat-sensitive layer, a low molecular weight organochlorine compound in the polyamide epichlorohydrin resin crosslinker is treated to make the content of the low molecular weight organic chlorine compound in the crosslinker 0.3%. The heat-sensitive recording material of Example 4 having a back coat layer was prepared using the above-mentioned solution E.

Use [0029] In Comparative Example 6 Example 4, instead of the low content of molecules organochlorine compound 0.3% crosslinking agent as a crosslinking agent, the content of low-molecular organic chlorine compound is 12% of a crosslinking agent A thermosensitive recording material of Comparative Example 6 having a back coat layer was prepared in the same manner as in Example 4 except for the difference.

Comparative Example 7 In the same manner as in Example 4, except that a crosslinking agent of a methylol resin was used in place of the crosslinking agent having a low-molecular-weight organic chlorine compound content of 0.3% as the crosslinking agent. Thus, a heat-sensitive recording material of Comparative Example 7 having a back coat layer was prepared.

The performance of the heat-sensitive recording materials of the examples and comparative examples obtained above was evaluated by the following methods. Table 1 shows the results. (1) Thermal head matching property Using a thermal printing apparatus equipped with a thermal head manufactured by Matsushita Electronic Components, a head voltage of 24 V and a printing energy of 0.45 were used.
Printing is performed for 100 m under the conditions of W / dot and pulse width of 1 msec, and changes in the printed image are observed. Amount of head scum adhered ○: There is no blurred printed image due to head scum adhered △: A little blurred printed image due to head scum adhered ×: A large amount of blurred printed image due to head scum adhered No ×: There is white spots on the printed image due to head breakage. (2) Dynamic sensitivity Using a thermal printing apparatus equipped with a thermal head manufactured by Matsushita Electronic Components, a head voltage of 24 V and a printing energy of 0.45.
Printing was performed under the conditions of W / dot and pulse width of 0.1 to 1.2 msec, the printing energy when the density became 1.0 was calculated by a Macbeth densitometer, and the numerical value of Example 1 was set to 1 as a relative value. It is shown by the ratio (the larger, the better the sensitivity). (3) Water resistance test The printed thermosensitive recording material was immersed in water at 20 ° C. for 3 hours and taken out. The overcoat layer provided the overcoat layer, and the backcoat layer provided the backcoat layer. The layer is rubbed with a finger ten times, and the degree of peeling of the film at that time is observed. Regarding the undercoat layer, it is observed whether or not the thermosensitive coloring layer and the support are separated. ；: No peeling ○: No peeling, but the surface is slimy △: Slightly peeling ×: Peeling completely (4) Plasticizer resistance After printing with a 150 ° C. heat block, the density is measured with a Macbeth densitometer The plasticizer DOA (dioctyl adipate) is provided with an overcoat layer, the surface of the overcoat layer is provided with an overcoat layer, and the undercoat layer and the backcoat layer are provided with absorbent cotton on the back surface of the support and the surface of the backcoat layer, respectively. Apply thinly and leave it at 40 ° C for 15 hours to measure the concentration.

[0032]

[Table 1]

[0033]

Heat-sensitive recording material of the present invention exhibits, an overcoat layer provided on the thermosensitive coloring layer, reducing the polyamide epichlorohydrin resin low molecular organic chlorine compounds as a crosslinking agent, a low molecular organic crosslinker resin component By controlling the content of the chlorine compound to 1% by weight or less, the head matching property is good, the head residue is less adhered, the electric corrosion of the head is less, the defect of the printed image due to the dot breakage of the head is eliminated, and the resistance is improved. It has excellent plasticizer properties and water resistance.
In addition, thermal recording materials using polyamide epichlorohydrin resin as a cross-linking agent for the resin of the undercoat layer and the backcoat layer can also suppress defects in printed images due to head dot breakage, and suppress migration of water and plasticizer from the back surface. Thereby, it becomes excellent in water resistance and plasticizer resistance.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-155985 (JP, A) JP-A-62-270383 (JP, A) JP-A-59-174388 (JP, A) JP-A 64-64 11883 (JP, A) JP-A-5-162443 (JP, A) JP-A-63-130367 (JP, A) JP-A-61-1191264 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41M 5/28-5/34

Claims (3)

(57) [Claims] 1. A heat-sensitive recording material having a thermosensitive coloring layer which develops color by heat on a support, provided an overcoat layer mainly composed of resin and a crosslinking agent in the thermosensitive color developing layer, low as crosslinking agent A thermosensitive recording material comprising a polyamide epichlorohydrin resin having a content of a molecular organic chlorine compound of 1% by weight or less. 2. A thermosensitive recording material comprising a support and a heat-sensitive coloring layer which is colored by heat.
An undercoat layer mainly composed of resin and a crosslinking agent provided between, the content of low-molecular organic chlorine compound 1 as a crosslinking agent
A heat-sensitive recording material characterized by using a polyamide epichlorohydrin resin in an amount of not more than 10% by weight. 3. A thermosensitive recording material provided with a thermosensitive coloring layer which develops a color by heat on a support, wherein a backcoat layer mainly composed of a resin and a crosslinker is provided on the backside of the support, and a low molecular weight compound is used as the crosslinker. A heat-sensitive recording material comprising a polyamide epichlorohydrin resin having an organic chlorine compound content of 1% by weight or less.