JP2847731B2 - Thermal recording medium and resin composition for overcoating of thermal recording medium - Google Patents

Description

The present invention relates to a thermosensitive recording medium and a resin composition for overcoating a thermosensitive recording medium. More specifically, the present invention relates to a heat-sensitive recording medium in which a heat-sensitive coloring layer and an overcoat layer are provided on a base material and a resin composition for overcoating the heat-sensitive recording medium, in particular, with improved surface gloss and head matching.

"Prior art" A heat-sensitive recording medium represented by a heat-sensitive paper is composed of a color former such as a leuco compound and an acidic substance which is a color former separately, or a color former such as a metal salt of an organic acid and a color former. Separately with a certain organic reducing agent, dispersed in the form of fine particles in a water or organic solvent medium containing a water-soluble binder or an organic solvent-based binder, and mixing both to make paper, synthetic paper, synthetic resin film, etc. Is applied on the base material. Specific examples of such a heat-sensitive recording medium are disclosed in, for example, JP-B-44-3680, JP-B-45-14039, and JP-A-48-17344. Since such a heat-sensitive recording medium is made by applying a fine particle dispersion of several μm or less on a substrate and drying the dispersion, fine particles of several μm or less are arranged on the surface and have irregularities, and have a defect that the gloss is low. doing. As a technique for obtaining a heat-sensitive recording medium having a high gloss surface property, there is a proposal to provide an intermediate layer having a specific smoothness on the heat-sensitive recording layer, and then overcoat with an electron beam-curable resin (Japanese Patent Application Laid-Open No. H10-163873). JP-A-59-26291, JP-A-62-279980).

[Problems to be Solved by the Invention] However, in the above-described heat-sensitive recording medium, the components of the heat-sensitive recording medium are melted and adhered (sticked) to the heat head or the heat pen during heating and coloring with the heat pen or the heat head, There is a tendency that the so-called head matching property, which causes adhesion, causes a decrease in the density and sharpness of the color image, distortion of the color image, inconvenience of paper feeding, or wear of the thermal head or thermal pen, is reduced.

In particular, thermal recording media with a high gloss surface, made of synthetic paper or synthetic resin sheet, have a smooth surface, so the contact area with the thermal head is large, frictional resistance is large, and sticking is likely to occur. Become. Further, when dust enters between the surface of the thermal recording medium and the thermal head for some reason, the surface is smooth, so that dust is not removed, and a print missing phenomenon easily occurs in an image continuously. Was.

"Means for Solving the Problems" In view of the present situation, a thermosensitive recording medium having a high gloss surface property, having no sticking and sticking, and having little wear of a thermal head or a thermal pen, that is, excellent in so-called head matching property. As a result of intensive research for the purpose of obtaining, as a resin composition for overcoating on a substrate, a heat-sensitive recording medium using an active energy ray-curable resin composition described below is, for example, a synthetic resin. The present inventors have found that the above-mentioned drawbacks do not exist even in the case of using a base material composed of, and have completed the present invention.

That is, the present invention uses this resin composition as an active energy ray-curable resin composition containing a silicone-based surfactant and / or a fluorine-based surfactant, and a resin composition for overcoating a heat-sensitive recording medium. It is intended to provide a thermosensitive recording medium.

As the base material used in the present invention, ordinary paper or paper or film containing a synthetic resin as a main component in order to enhance the gradation of an image, for example, synthetic paper or synthetic resin film is suitably used. Examples of the synthetic resin film include conventionally known synthetic resin films such as a polyester film, a polyolefin film, a cellulosic film, and a polyamide film.

Further, the thermosensitive coloring layer is formed by applying a coating liquid containing a coloring agent and a coloring agent to the base material. The combination of the color former and the color former is not limited at all, and any combination may be used as long as the two come into contact with each other by heat to cause a color reaction, such as a colorless or pale base. Combination of acidic dyes and inorganic or organic acidic substances, stearic acid secondary
There is a combination of a metal salt of a higher fatty acid such as iron and an organic reducing agent such as gallic acid, but a combination of a basic dye and an acidic substance is preferable from the viewpoint of image clarity.

Then, these color formers and color formers are blended in predetermined amounts, and if necessary, appropriate additives are added thereto,
After being dispersed and stirred in a dispersion medium to form a coating solution for the thermosensitive coloring layer, it is applied on the base material to form a thermosensitive coloring layer. The coating method is not particularly limited, and it can be formed according to a well-known and commonly used technique.

The heat-sensitive recording medium of the present invention is provided with an overcoat layer obtained by curing with an active energy ray on the surface of the heat-sensitive coloring layer thus obtained, and an intermediate layer may be provided therebetween. . The coating liquid used for the intermediate layer may be any coating liquid as long as it does not damage the heat-sensitive starting layer, but a coating liquid containing an aqueous resin as a main component is generally used.
As the aqueous resin, various modified polyvinyl alcohols, starches, various cellulose derivatives and the like are usually used, and among them, epoxidized polyvinyl alcohol, acetoacetylated polyvinyl alcohol and carboxy-modified polyvinyl alcohol are preferably used. In order to increase the smoothness of the intermediate layer, an inorganic pigment such as calcium carbonate or aluminum oxide, or a pigment such as an organic powder such as nylon powder can be added. Various assistants such as an ultraviolet absorber, an antifoaming agent, a fluorescent dye and a coloring dye may be added. Then, each of these compounds is blended in a predetermined amount, mixed and stirred to form a coating solution for the intermediate layer, and then applied on the thermosensitive coloring layer by various coating methods to form an intermediate layer. .

In the thermosensitive recording medium of the present invention, an overcoat layer obtained by curing with an active energy ray is provided on the surface of the thermosensitive coloring layer having or not having one or two or more intermediate layers thus formed. The coating layer is in direct contact with a thermal head or a thermal pen, is subjected to a high pressure, and is subjected to a high temperature, so that abrasion resistance, toughness, and heat resistance are required.

In order to obtain such a coating film performance, the active energy ray-curable resin composition used as the resin composition for overcoating the thermal recording medium of the present invention comprises an active energy ray-curable compound (a) and a silicone-based surfactant. (B ₁ ) and / or a fluorine-based surfactant (b ₂ ).

As the silicone-based surfactant (b ₁ ), those having an oxyalkylene group are preferable, and among them, the general formula (1): [Where X is m and n are integers of 1 or more, x and y are 0 or an integer of 1 or more, R ₁ , R ₂ , R ₃ and R ₅ are an alkyl group, R ₄ is a hydrogen atom, an alkyl group, an acyl group or an aryl group. Represent.
Here, m, n, x and y are represented by the following formula: 0.1 ≦ n (x + y)
/ 2m ≦ 10. Or the general formula (2); [Where Y is p and q are integers of 1 or more, s and t are 0 or an integer of 1 or more, z is 0 or an integer of 1 to 5, R ₆ , R ₇ , R ₈ , R ₉
And R ₁₁ are an alkyl group, R ₁₀ is a hydrogen atom, R ₁₂ represents an alkyl group, an acyl group or an aryl group, a hydrogen atom, an alkyl group, an acyl group or an aryl group. However, R ₁₃ , R ₁₄ and R ₁₅ represent an alkyl group, p,
q, s and t are values satisfying the following formula: 0.1 ≦ q (s + t) / 2p ≦ 10. Has an effect of improving the sticking property without lowering the surface gloss of the heat-sensitive recording medium. However, the silicone surfactant (b ₁ ) represented by the above formulas (1) and (2) is represented by m
What is known as a mixture of compounds having different p and n and a mixture of compounds having different p and q can also be used.

As the fluorine-based surfactant (b ₂ ), an ionic, cationic, anionic or amphoteric surfactant can be used as long as it has good compatibility with the active energy ray-curable compound (a) and exhibits surface activity. Any fluorine-based surfactant may be used. Specifically, for example, anionic surfactants such as fluoroalkoxypolyfluoroalkyl sulfates, fluorocarbon sulfonates, and fluorocarbon carboxylate salts, for example, N-fluoroalkylsulfonamidoalkylamine salts, N-fluoroalkylamidoalkylamines Cationic surfactants such as quaternary ammonium salts, N-fluoroalkylsulfonamidoalkylhacomethyl ether quaternary ammonium salts,
Fluorocarbon sulfonamide, fluorocarbon amino sulfonamide, fluorocarbon carboxy sulfonamide, fluorocarbon hydroxy sulfonamide, fluorocarbon sulfonamide ethylene oxide adduct, fluorocarbon hydroxy sulfonamide sulfate, fluorocarbon amino acid amide,
Fluorocarbon amides, fluorocarbon hydroxy amides, fluorocarbon amide ethylene oxide adducts, fluorocarbon hydroxy amide sulfates, fluorocarbon hydroxy amide phosphates, fluorocarbon sulfonic acids,
Nonionic surfactants such as fluorohydrocarbon alkyl esters, fluorocarbon hydroxyamides, fluorohydrocarbon alkyl sulfates, and fluoroalkyldiamines, for example, alkylamines having a betaine-type fluorocarbon sulfonamide bond, betaine-type fluorocarbonamides Examples include amphoteric surfactants such as alkylamines having a bond.
In consideration of sticking property and compatibility, it is particularly preferable to use a nonionic surfactant.

These silicone surfactants (b ₁ ) and / or fluorine surfactants (b ₂ ) may be used alone or in combination.

The active energy ray-curable compound (a) comprises an active energy ray-curable prepolymer (A) and an active energy ray-curable reactive diluent (B) having a hydrophilic group.
And an active energy ray-curable compound (C) having no unsaturated bond, which is added as necessary.

Examples of the active energy ray-curable prepolymer (A) used herein include polyether (meth) acrylate-based prepolymer, polyester (meth) acrylate-based prepolymer, polyol (meth) acrylate-based prepolymer, and epoxy (meth) ) Acrylate prepolymers, amide urethane (meth) acrylate prepolymers, urethane (meth) acrylate prepolymers, spiroacetal (meth) acrylate prepolymers, and polybutadiene (meth) acrylate prepolymers. The active energy ray-curable prepolymer (A) can be added alone or as a mixture of two or more.

Above all, as the component (A), the general formula (3) is excellent in heat resistance and abrasion resistance; [Wherein, l is an integer of 0 to 4, and Z is at least 3 or more in the general formula: (In the formula, R ₁₆ represents a hydrogen atom or an alkyl group, and R ₁₇ represents an alkylene group having 1 to 8 carbon atoms or 1 to carbon atoms.
Represents a polyoxyalkynone group having 8 alkylene groups. Represents a group represented by), the remainder is an alkyl group having 1 to 8 carbon atoms, a hydroxyl group, an amino group, wherein: in OR _{18 k} H (wherein, R ₁₈ represents an alkylene group having 1 to 8 carbon atoms, k
Is a positive integer. ) Or a group represented by the formula: OR ₁₈
represents a group represented by _k OH (wherein R ₁₈ and k are the same as described above). It is preferable to use a compound represented by the following formula:

Specific examples of the compound represented by the general formula (3) include pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, tripentaerythritol pentaacrylate, Examples include tripentaerythritol hexaacrylate, tripentaerythritol heptaacrylate, and the like.

The active energy ray-curable reactive diluent (B) used in combination with the component (A) to adjust the viscosity of the coating liquid containing these active energy ray-curable compounds includes active energy ray-curable compounds. And having a hydrophilic group in the molecule, and the hydrophilic group improves the adhesion to the intermediate layer. As the hydrophilic group, a phosphate group,
Examples include a carboxylic acid group, an acrylamide group, a pyrrolidone group, a morpholyl group, an amino group, a hydroxyl group, an epoxy group, a caprolactam group, an isocyanate group, and a tetrahydrofurfuryl group. Specific examples include 2-hydroxyethyl (meth) acryloyl phosphate, (meth) acrylic acid, β-hydroxyethyl (meth) acrylate / phthalic anhydride (1/1) reactant, N-methyl (meth) acrylamide, N , N-dimethylaminopropyl (meth) acrylamide, Nn-butoxymethyl (meth) acrylamide, N, N'-methylenebis (meth) acrylamide, vinylpyrrolidone, (meth) acryloylmorpholine, diethylaminoethyl (meth) acrylate, β −
Hydroxyethyl (meth) acrylate, β-hydroxypropyl (meth) acrylate, glycidyl (meth)
Acrylate, vinylcaprolactam, β-hydroxyethyl (meth) acrylate / isophorone diisocyanate (1/1) reactant, tetrahydrofurfuryl (meth)
Acrylate and the like.

Specific examples of the active energy ray-curable compound (C) having no unsaturated bond include an alkyl (meth) acrylate polymer, an epoxy resin, a liquid polybutadiene,
Liquid polybutadiene derivative, liquid chloroprene, liquid polypentadiene, dicyclopentadiene derivative, saturated polyester oligomer, polyether oligomer, liquid polyamide, polyisocyanate oligomer, xylene resin, ketone resin, petroleum resin, fluorine oligomer, silicone oligomer, poly Sulfite oligomers and the like can be mentioned. Particularly preferred are alkyl (meth) acrylate polymers, and specific examples thereof include homopolymers such as methyl methacrylate, sec-butyl methacrylate, cyclohexyl methacrylate, isobutyl methacrylate, benzyl methacrylate, phenyl methacrylate, and ethyl methacrylate; methyl methacrylate / styrene = 80/20 parts by weight, methyl methacrylate / ethyl acrylate = 95/5, methyl methacrylate / methyl acrylate = 90/10, methyl methacrylate / n-butyl methacrylate = 40/60, methyl methacrylate / ethyl methacrylate = 30/70, methyl methacrylate / Ethyl acrylate = 70/30, methyl methacrylate / methyl acrylate / methacrylic acid = 60/35/5, methyl methacrylate / lauryl methacrylate = 90/10, methyl methacrylate Rate / methyl acrylate / 2-hydroxyethyl methacrylate = 80/15/5, methyl methacrylate /
Copolymers such as iso-butyl methacrylate / dimethylaminoethyl methacrylate = 80/15/5 can be mentioned. These polymers can be used alone or as a mixture of two or more. Is also good.

When ultraviolet rays are used as the radiation source, one or more compounds having at least one methacryloyloxy group or at least one acroyloxy group in the polymerizable group are used in the components (A) and (B). Is preferred.

The amount of the silicone surfactant (b ₁ ) and / or the fluorine surfactant (b ₂ ) occupied in the active energy ray-curable resin composition is determined by adding both (= (b ₁ ) + (B ₂ )), which is in the range of 0.01 to 15 parts by weight with respect to 100 parts by weight of the active energy ray-curable resin composition (a) (= (A) + (B) + (C)). The amount is more preferably in the range of 0.1 to 10 parts by weight from the viewpoint that the effect of improving the sticking property is sufficiently obtained.

Also, the compounding amounts of the active energy ray-curable prepolymer (A), the reactive diluent (B) and the active energy ray-curable type compound having no unsaturated bond (C) are as follows:
The resin component, that is, 100 parts by weight of the active energy ray-curable resin composition (a) (= (A) + (B) + (C)), is usually 40 to 100 parts by weight of (A) and (B), respectively. ) Is in the range of 0 to 60 parts by weight, and (C) is in the range of 0 to 40 parts by weight. Among them, a resin composition for an overcoat in which the viscosity is appropriate, the curing shrinkage is small, and sticking is particularly hard to occur is obtained. (A) is 50 to 95 parts by weight, (B) is 10 to
It is preferable that 50 parts by weight and (C) be in the range of 5 to 35 parts by weight.

In addition, in this resin composition, if necessary, a thermal polymerization inhibitor, an organic silane compound, a leveling agent, an antifoaming agent, a slip agent, a pinhole / crater inhibitor, a wetting modifier, etc. Various additives such as an agent, a plasticizer, and a coloring agent can also be added.

The active energy rays used for curing these resin compositions include ultraviolet rays and electron beams, α rays, β rays.
Ray, refers to ionizing radiation such as γ-rays, it is preferable to include a photopolymerization initiator and / or a photosensitizer in the resin composition for overcoating when using ultraviolet rays. When such an ionizing radiation is used, it is rapidly cured without including a photopolymerization initiator or a photosensitizer, and therefore, it is not necessary to particularly add it.

Then, the resin composition obtained by blending each of these components is sufficiently mixed by a suitable mixing stirrer such as a mixer, and then applied onto the intermediate layer or the thermosensitive coloring layer. The viscosity can be adjusted by heating according to the temperature.

The application method may be a method according to well-known and commonly used techniques,
A method such as gravure coating, roll coating, air knife coating or flow coating is more preferable in that a coated surface having a high gloss surface can be obtained. The coating amount of the overcoat resin composition is not necessarily limited,
Usually, the range of 0.1 to 20 g / m ² is good.

In addition, at the time of curing, not only active energy rays but also heat may be used for curing. However, the heating must be performed to such an extent that the thermosensitive recording medium does not develop color. In the case of curing using both heat and active energy rays, a radical polymerization initiator and a curing accelerator may be added to the overcoat resin composition.

In the case of curing using both active energy rays and heat, either one may be used first. That is, after curing by heat, it may be cured by active energy rays,
After the irradiation with the active energy ray, heat curing may be performed.
The active energy ray may be irradiated while heating.

As an atmosphere for irradiating an active energy ray such as an ultraviolet ray or an electron beam, an inert gas atmosphere such as a nitrogen gas or a carbon dioxide gas or an atmosphere having a reduced oxygen concentration is naturally preferable, but a normal air atmosphere may be used.

Hereinafter, the present invention will be described in more detail with reference to Examples.
Of course, it is not limited to these. Unless otherwise specified, parts and% in the examples indicate parts by weight and% by weight, respectively.

Example 1 (I) Preparation of Liquid (Coloring Agent Dispersion) 3-Diethylamino-6-methyl-7-anilinofluoran 5.0 parts Stearic acid amide 10.0 parts 10% aqueous polyvinyl alcohol solution [Kuraray PVA Co., Ltd.]
-117] 7.5 parts water 25.5 parts Total 47.5 parts This composition was ground with a paint shaker until the average particle diameter became 3 μm.

(II) Preparation of Liquid (Coloring Agent Dispersion) Bisphenol A 17.5 parts Calcium carbonate 17.5 parts 10% aqueous polyvinyl alcohol solution 7.5 parts Water 50.0 parts Total 92.5 parts This composition was pulverized with a paint shaker until the average particle diameter became 3 μm.

Preparation of recording layer (I) solution 47.5 parts (II) solution 92.5 parts 40% glyoxal aqueous solution 2.5 parts 10% polyvinyl alcohol aqueous solution 25.0 parts water 7.5 parts Total 175.0 parts This composition was thoroughly stirred and mixed, and 50% triethanolamine was added. The pH was adjusted to 8 with an aqueous solution to obtain a coating solution for a heat-sensitive recording layer.

The obtained coating solution was used for commercial synthetic paper (Oji Yuka Synthetic Paper FP).
G # 60) was applied using a Meyer bar so that the coating amount after drying was 8 g / m ² , and dried and cured with a dryer at 50 ° C. to obtain a thermosensitive recording medium.

Intermediate layer formation 10% acetoacetylation 100 parts Polyvinyl alcohol aqueous solution [Z-100 manufactured by Nippon Synthetic Chemical Industry Co., Ltd.] Calcium carbonate 10 parts Water 10 parts Total 120 parts This composition was dispersed using a paint shaker, and then this coating liquid was applied. the on the recording layer of the thermosensitive recording media obtained in the previous section was applied as the coating amount after drying of the 4g / m ² using a Meyer bar, dried, and cured at a 50 ° C. oven, the intermediate layer A thermosensitive recording medium having the above was prepared.

Formation of Overcoat Layer On the intermediate layer of the heat-sensitive recording medium having the intermediate layer, the dry coating amount of the overcoat resin composition having the composition shown in Table 1 is shown.
The coating is 4g / m ^2, an ultraviolet lamp (Ai Cure Light H03-L31 manufactured by Eye Graphics Co., Ltd., 3 lights)
UV light was applied at a distance of 17 cm from the lamp and a transport speed of 30 m / 1 minute to cure the coating layer to obtain a thermosensitive recording medium having an overcoat layer of the present invention.

1) PE3A: pentaerythritol triacrylate 2) DP6A: dipentaerythritol hexaacrylate 3) Epoxy acrylate: Lipoxy SP-1509 (manufactured by Showa Polymer Co., Ltd.) 4) Urethane acrylate: Ebecryl 220 (manufactured by UCB) 5) Polyester acrylate: Ebecryl 810 (manufactured by UCB) 6) HEA: hydroxyethyl acrylate 7) N-VP: N-vinylpyrrolidone 8) PA: 2-acryloyloxyethyl phosphate 9) DEAEA: diethylaminoethyl acrylate 10) AA: acrylic Acid 11) 3P2A: Tripropylene glycol diacrylate 12) Acrylic polymer A: Copolymer of butyl methacrylate / methyl methacrylate = 60/40, Tg50 ° C 13) High molecular weight tertiary amine: Ubecryl P115 manufactured by UCB, Belgium 14) High molecular weight benzophenone : Ubecryl P3 manufactured by UCB, Belgium 6 15) CADOX B-CH50: Peroxide manufactured by Kayaku Nury Co., Ltd. 16) Epoxysilane: γ-glycidoxypropyltrimethoxysilane 17) Aminosilane: N- (β-aminoethyl) γ-aminopropylmethyldimethoxysilane 18) Kayasetable-N: Dye manufactured by Nippon Kayaku Co., Ltd. 19) Silicone surfactant A: (N / m = 2, a mixture of compounds different from m and n) 20) Silicone surfactant B: (23n / 2m + n = 3, mixture of compounds different from m and n) 21) Fluorosurfactant A: Megafac F-171 (manufactured by Dainippon Ink and Chemicals, Inc.) 22) Fluorosurfactant B: Megafac F-177 (manufactured by Dainippon Ink and Chemicals, Inc.) (Example 2) In Example 1, except that the composition shown in Table 1 was used as the overcoat layer, an overcoat layer was provided. A thermosensitive recording paper was obtained.

(Examples 3 to 9) In Example 1, the following composition was used as the intermediate layer, and 100 parts of 5% epoxidized polyvinyl alcohol aqueous solution (trade name: DR-587, manufactured by Denki Kagaku KK) 10 parts of calcium carbonate Water 20 parts 130 parts A heat-sensitive recording paper having an overcoat layer was obtained in the same manner except that the composition shown in Table 1 was used as the overcoat layer.

(Example 10) In Example 1, the following composition was used as the intermediate layer. 10% carboxylic acid-modified 100 parts polyvinyl alcohol aqueous solution (trade name KLB-118, manufactured by Kuraray Co., Ltd.) Calcium carbonate 10 parts Water 10 parts Total 120 Part The composition shown in Table 1 was used as the overcoat layer,
In the same manner as in Example 1, a thermosensitive recording paper having an overcoat layer was obtained.

(Example 11) In Example 3, the composition shown in Table 1 was used as an overcoat layer, and after irradiating with an ultraviolet lamp under the same conditions as in Example 3, the coating film was cured at 60 ° C for 5 minutes and overcoated. A thermosensitive recording paper having a coat layer was obtained.

 In addition, what passed 24 hours at room temperature was evaluated.

(Example 12) In Example 3, the composition shown in Table 1 was used as the overcoat layer, and the dry coating amount was 3 g / m ² on the intermediate layer.
And irradiate 4Mrad with an electron curtain type electron beam irradiation device (CB150 type, manufactured by ESI).
The coating film was cured to obtain a thermal paper having an overcoat layer.

(Example 13) A thermal paper having an overcoat layer was obtained in the same manner as in Example 1, except that the composition shown in Table 1 was used as the overcoat layer.

(Comparative Examples 1 and 2) A thermal paper having an overcoat layer was obtained in the same manner as in Example 1, except that the composition shown in Table 1 was used as the overcoat layer.

The thermal performance recording media of Examples 1 to 13 and Comparative Examples 1 and 2 obtained as described above were subjected to the following quality performance tests.

 Table 2 shows the test results.

1) Sticking: When a thermosensitive recording medium was printed with a commercially available image printer [UP-701 manufactured by Sony Corporation], the adhesion state of the sample to the thermal head was visually judged.

No sticking (very good) ○, no sticking (good) 、, no sticking (normal) △, sticky (bad) x, sticky (notably bad) xx.

2) Adhesion of scum: When printing on the thermal recording medium with the above-mentioned image printer, the state of scum adhesion to the thermal head was visually judged.

No scum adhesion (very good) な し, no scum adhesion (good) 、, no scum adhesion (normal) △, scum adhesion (bad) x, scum adhesion (significantly poor) xx 3) Print missing: the image above When printing on the thermosensitive recording medium with a printer, the state of missing prints continuously appearing on the image surface was visually judged.

No missing print (very good) ○, no missing print (good) 、, no missing print (normal) △, missing print (bad) ×, missing print (significantly bad)
XX 4) Print density: The density printed (solid black) by the above-mentioned image printer was measured with a Macbeth reflection densitometer (RD-100R, manufactured by Macbeth).

5) Gloss: The gloss of the surface of the thermal recording medium before printing is measured with a digital gloss meter (GM-3D, manufactured by Murakami Color Research Laboratory).
Measured at a 60 ° incidence angle.

6) Plasticizer resistance: The colored thermal recording medium is sandwiched between vinyl chloride wraps (three layers) containing a plasticizer, brought into contact with the coloring surface, and the pressure is 10 g / cm ² and the ambient temperature is 40 ° C.
The degree of decoloration of the image after standing for one day and night was visually determined.

No change (extremely good) 変 化, no change (good) 、, no change (normal) △, slightly erased (bad) ×, erased more than half (significantly poor) XX 7) Water resistance: printing After the color-developed thermosensitive recording medium was immersed in water for 5 minutes, the surface thereof was rubbed five times with gauze, and the degree of decolorization of the image was visually determined.

No change (very good) 良 い, no change (good) 、, no change (normal) △, slight surface (bad) x,
Decoloring (significantly bad) xx 8) Moisture resistance: After leaving the heat-sensitive recording medium with printed color in a constant temperature room at 40 ° C and 95% RH for 24 hours, the degree of decoloration of the image was visually determined. .

No change (extremely good) 変 化, no change (good) 、, no change (normal) △, slightly erased (bad) x, erased more than half (significantly bad) xx 9) Oil resistance: printing Several drops of salad oil were dropped on the color-developed thermosensitive recording medium. After 30 minutes, the salad oil was wiped off with a gauze, and then the degree of decolorization of the image was determined.

No change (very good) ○, no change (good) 、, no change (normal) △, slightly erased (bad) ×, half or more erased (significantly poor) XX clear from Table 2 As described above, the heat-sensitive recording medium using the composition of the example had high surface gloss and excellent head matching. On the other hand, in the heat-sensitive recording media of Comparative Examples (Comparative Examples 1 and 2) using the resin composition containing neither the silicone-based surfactant nor the fluorine-based surfactant, sticking occurs. Also, the surface smoothness was low.

"Effect of the Invention" As described above, the thermosensitive recording medium of the present invention is
A thermosensitive coloring layer, and an overcoat layer comprising an active energy ray-curable resin composition containing a silicone-based surfactant and / or a fluorine-based surfactant, wherein the active energy ray-curable resin composition is An active energy ray-curable prepolymer (A) and an active energy ray-curable compound (a) containing an active energy ray-curable reactive diluent (B) having a hydrophilic group, and a silicone-based Since the surfactant and / or the fluorine-based surfactant is contained in an amount of 0.01 to 15 parts by weight based on 100 parts by weight of the resin component, in addition to having excellent surface gloss,
There is no inconvenience that the components of the heat-sensitive recording medium are melted and adhered (sticked) to the hot pen or the hot head even when the color is heated by the hot pen or the hot head. In addition, the color recording image is clear, and there is no problem such as distortion of the image or inconvenience such as paper feeding, or a problem such as abrasion of a hot pen or a thermal head. In particular, even when a synthetic paper or a synthetic resin sheet is used as the base material, it is possible to obtain a heat-sensitive recording medium that maintains excellent surface gloss and does not cause sticking. Further, there is an advantage that each performance such as toughness, heat resistance, and wear resistance is extremely excellent.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-197687 (JP, A) JP-A-63-214475 (JP, A) JP-A-62-11680 (JP, A) JP-A-57-19757 107884 (JP, A) JP-A-59-29194 (JP, A) JP-A-63-67189 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41M 5 / 28-5 / 34

Claims (2)

(57) [Claims] 1. A thermosensitive coloring layer and an overcoat layer comprising an active energy ray-curable resin composition containing a silicone-based surfactant and / or a fluorine-based surfactant are provided on a substrate, The active energy ray-curable resin composition contains an active energy ray-curable compound (a), and the active energy ray-curable compound (a) comprises an active energy ray-curable prepolymer (A) and an active energy ray-curable compound. It contains a reactive diluent (B) which is curable and has a hydrophilic group, and contains the silicone-based surfactant and / or the fluorine-based surfactant in an amount of 0.01 to 15 parts by weight based on 100 parts by weight of the resin component. A heat-sensitive recording medium characterized in that: 2. An active energy ray-curable compound (a),
The active energy ray-curable compound (a) contains a silicone-based surfactant and / or a fluorine-based surfactant, and the active energy ray-curable prepolymer (A) and the active energy ray-curable compound, and The reactive diluent (B) having a hydrophilic group is contained, and the silicone-based surfactant and / or the fluorine-based surfactant are contained in an amount of 0.01 to 15 parts by weight based on 100 parts by weight of the resin component. A resin composition for overcoating of a heat-sensitive recording medium.