JPH0775913B2 - Method for manufacturing thermosensitive recording medium - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a heat-sensitive recording material in which a color former and a color former react with each other when heat is applied to obtain a color image.

[0002]

2. Description of the Related Art Conventional thermal recording materials used in a wide range of fields such as facsimiles, various printers, and electrocardiograms become unreadable when they are exposed to high humidity after recording. Or water adheres to the recorded image,
There is a drawback that the recorded image is lost when the portion is rubbed by a hand or clothes. Further, there is a drawback that the solvent resistance is poor and, for example, when a solvent contacts the recording layer, the recording density is lowered.

[0003]

DISCLOSURE OF THE INVENTION The object of the present invention is to have drawbacks inherent in the above-mentioned conventional thermal recording materials, namely, weaknesses in humidity resistance and water resistance, oil resistance, plasticizer resistance and solvent resistance. It is an object of the present invention to provide a method for manufacturing a thermal recording material that solves the above problem.

[0004]

According to the present invention, a support is coated with a coating liquid for a thermosensitive recording medium containing a color former, a color former, and a water-soluble and / or water-dispersible adhesive as main components, and then dried. , A water-soluble adhesive that does not have an ethylenically unsaturated bond on this coated surface , or a water-soluble adhesive that does not have an ethylenically unsaturated bond.
A method for producing a thermosensitive recording medium, which comprises irradiating an electron beam after applying a binder and an electron beam curable resin emulsion.

[0005]

With respect to the constitution of the invention described above, examples of the combination of the color former and the color former include a combination of a colorless or pale basic dye and an inorganic or organic acidic substance, a higher fatty acid such as ferric stearate and gallic acid. And a combination of a diazo compound and a coupler, and the like.

Various types of basic dyes that are colorless or light-colored are known, and examples thereof include triallylmethane dyes, diphenylmethane dyes, thiazine dyes, spiro dyes, lactam dyes, and fluorane dyes. Etc. are appropriately selected and used. Various kinds of inorganic or organic acidic substances are known, and for example, various phenolic compounds, aromatic carboxylic acids or polyvalent metal salts thereof are appropriately selected and used.

The coating liquid containing these color formers and color formers is generally prepared by using water as a dispersion medium and an agitator / pulverizer such as a ball mill, an attritor or a sand grinder. Further, in the coating liquid, usually, a water-soluble or water-dispersible adhesive, for example polyvinyl alcohol, acetoacetylated polyvinyl alcohol, modified polyvinyl alcohol containing silicon in the molecule, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose. , Casein, gum arabic, oxidized starch, etherified starch, esterified starch, saponified copolymer of vinyl ether and a monomer copolymerizable therewith (as the monomer, for example, ethylene, propylene, isobutylene, Olefins such as α-octene, α-dodecene, α-octadodecene, acrylic acid, methacrylic acid,
Crotonic acid, maleic acid, maleic anhydride, unsaturated acids such as itaconic acid or salts thereof further mono or dialkyl esters, acrylonitrile, nitriles such as methacrylonitrile, amides such as acrylamide, methacrylamide, ethylene sulfonic acid, Olefin sulfonic acid such as allyl sulfonic acid or a salt thereof, alkyl vinyl ethers, vinyl ketone, N-vinylpyrrolidone, vinyl chloride, vinylidene chloride and the like can be mentioned. ), Styrene-butadiene copolymer emulsion,
A vinyl acetate-ethylene copolymer emulsion, a vinyl acetate-vinyl chloride-ethylene copolymer emulsion, a methacrylate-butadiene copolymer emulsion, etc. are 10 to 40% by weight, preferably 15 to 30% by weight of the total solid content.
Used to a degree.

[0008] It should be noted that to these adhesives, a water resistant agent such as glyoxal, methylolmelamine, potassium persulfate, ammonium persulfate, sodium persulfate, ferric chloride, magnesium chloride, boric acid or ammonium chloride may be added. Good. Furthermore, in the coating liquid, for example, sodium dioctylsulfosuccinate, sodium dodecylbenzene sulfonate, a dispersant such as sodium salt of lauryl alcohol sulfate ester, an ultraviolet absorber such as a triazole-based defoamer, a fluorescent dye, Various auxiliaries such as coloring dyes can be added.

Further, stearic acid, polyethylene, carnauba wax, paraffin wax, zinc stearate, calcium stearate, and the like so that the thermal recording medium does not come into contact with the recording equipment or the recording head to cause sticking.
It is also possible to add a dispersant such as ester wax or an emulsion. In addition, kaolin, clay, talc,
Inorganic drinkable pigments such as calcium carbonate, calcined clay, titanium oxide, diatomaceous earth, fine anhydrous silica and activated clay can also be added.

If desired, stearic acid amide, stearic acid methylene bisamide, oleic acid amide, palmitic acid amide, mackerel oleic acid amide, coconut fatty acid amide and the like can be added as a sensitizer. Such a coating liquid is applied onto a support such as paper, synthetic paper or film by an application means such as air knife coating or blade coating and dried.

Although the coating amount of the coating liquid is not limited,
Dry weight is ² to 12 g / m ² , preferably 3 to 10 g / m ² .
It will be applied in the range of m ² . Next, a water-soluble adhesive that does not have an ethylenically unsaturated bond , or ethylenic
The electron beam is irradiated after coating the water-soluble adhesive having no unsaturated bond and the electron beam curable resin emulsion, but the irradiation may be performed immediately after coating, or after coating and drying. It may be irradiated.

As the water-soluble adhesive having no ethylenically unsaturated bond used in the present invention, for example, polyvinyl alcohol, acetoacetylated polyvinyl alcohol, modified polyvinyl alcohol containing silicon in the molecule,
Methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, casein, gum arabic, oxidized starch, etherified starch, esterified starch and the like are used.

The electron beam curable resin emulsion used in the present invention contains at least one prepolymer or monomer having an ethylenically unsaturated double bond, and the prepolymer is (a) ) Poly (meth) of aliphatic, alicyclic, araliphatic polyhydric alcohols having 2 to 6 valences and polyalkylene glycols
Acrylate. (B) A poly (meth) acrylate of a polyhydric alcohol in the form of an alkylene oxide added to an aliphatic, alicyclic, araliphatic, or aromatic 2- to 6-valent polyhydric alcohol. (C) Poly (meth) acryloyloxyalkyl phosphate ester. (D) Polyester (meth) acrylate. (E) Epoxy poly (meth) acrylate. (F) Polyurethane poly (meth) acrylate. (G) Polyamide poly (meth) acrylate. (H) Polysiloxane poly (meth) acrylate. (I) A vinyl-based or diene-based low weight product having a side chain and / or a terminal (meth) acryloyloxy group. (J) The oligoester (meth) acrylate-modified product described in (a) to (i) above. Etc. are illustrated.

As the monomer, I is a monofunctional unsaturated monomer. Carboxyl group-containing monomers represented by ethylenically unsaturated monomers or polycarboxylic acids, and carboxylic acid group-containing monomers such as alkali metal salts, ammonium salts and amine salts thereof. 2. Amide group-containing monomers represented by vinyl lactams such as ethylenically unsaturated (meth) acrylamide or alkyl-substituted (meth) acrylamide, N-vinylpyrrolidone. 3. A sulfonic acid group-containing monomer typified by an aliphatic or aromatic vinyl sulfonic acid, and a sulfonic acid group-containing monomer such as an alkali metal salt, ammonium salt or amine salt thereof. 4. A hydroxyl group-containing monomer represented by ethylenically unsaturated ether. 5. Amino group-containing monomers such as dimethylaminoethyl (meth) acrylate 2-vinylpyridine. 6. Quaternary ammonium salt-containing monomer. 7. Alkyl ester of ethylenically unsaturated carboxylic acid. 8. A nitrile group-containing monomer such as (meth) acrylonitrile. 9. styrene. Ten. Esters of ethylenically unsaturated alcohols such as vinyl acetate and (meth) allyl acetate. 11. Alkylene oxide addition polymers of active hydrogen-containing compounds, mono (meth) acrylates.

II Functionally Unsaturated Monomers 1. An ester group-containing bifunctional monomer represented by a diester of a polybasic acid and an unsaturated alcohol. 2. A diester of an alkylene oxide adduct of a compound having active hydrogen and (meth) acrylic acid 2
Functional monomer. 3. Bisacrylamides such as N, N-methylenebisacrylamide. 4. Divinylbenzene, divinylethylene glycol,
Bifunctional compounds such as divinyl sulfone, divinyl ether and divinyl ketone.

III Polyfunctional Unsaturated Monomer 1 An ester group-containing polyfunctional monomer represented by a polyester of a polycarboxylic acid and an unsaturated alcohol. 2. A polyfunctional monomer comprising a polyester of (meth) acrylic acid and an alkylene oxide adduct of a compound having active hydrogen. 3 A polyfunctional unsaturated monomer such as trivinylbenzene. Etc. Such monomers or prepolymers are prepared as oil-in-water emulsions by adding water with stirring in the presence of a surfactant.

Examples of the surfactant include aliphatic salts, higher alcohol sulfate ester salts, alkylbenzene sulfonates, alkylnaphthalenesulfonates, naphthalenesulfonic acid formalin condensates, dialkylsulfosuccinates, alkylphosphate salts and polyoxys. Anionic surfactants such as ethylene sulfate salt; nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkylphenol, sorbitan aliphatic ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene acyl ester, etc. A cationic surfactant such as an alkylamine salt, a quaternary ammonium salt, or polyoxyethylene alkylamine; or one of water-soluble polymers such as polyvinyl alcohol Two or more can be used alone or in combination, are best suited in that brings an emulsion with a stability nonionic surfactants, especially more than HLB10 Among these stand out.

These surfactants are generally used in the range from 0.01% to 20% by weight, particularly preferably in the range from 0.05% to 10% by weight, based on the monomers or prepolymers. Therefore, if a part of the adhesive is replaced with the electron beam curable resin emulsion described above, the reason why the moisture resistance and the water resistance are further improved is that the existence of the resin emulsion having many active sites probably causes the irradiation of the electron beam. It is thought that this is to further accelerate the crosslinking reaction upon receiving.

This coating solution contains glyoxal, methylolmelamine, potassium persulfate, ammonium persulfate,
You may add waterproofing agents such as sodium persulfate, ferric chloride, magnesium chloride, boric acid, ammonium chloride,
Further, in the coating liquid, for example, sodium dioctylsulfosuccinate, sodium dodecylbenzene sulfonate, a dispersant such as lauryl alcohol sulfate / sodium salt, an ultraviolet absorber such as a triazole type, other defoaming agent, a fluorescent dye, and a coloring agent. Various auxiliaries such as dyes can be added. Further, a dispersant or emulsion such as stearic acid, polyethylene, carnauba wax, paraffin wax, zinc stearate, calcium stearate, ester wax, etc. is added so that the thermal recording paper does not come in contact with the recording equipment or the recording head to cause sticking. You can also Further, in order to improve the adhesion of the dust to the recording head, it is possible to add kaolin, clay, talc, calcium carbonate, calcined clay, titanium oxide, diatomaceous earth, fine anhydrous silica, activated clay and other drinking inorganic pigments.

In the present invention, a water-soluble adhesive having no ethylenically unsaturated bond on the surface of the thermosensitive recording layer , or
Is a water-soluble adhesive that does not have an ethylenically unsaturated bond.
And the amount of the electron beam irradiated after coating with the electron beam curable resin emulsion or after coating and drying is 0.1 to 15 Mrad.
Is preferred. The reason for this is that irradiation curing with an electron beam is poor at 0.1 Mrad or less, and color smearing on the coated surface occurs at 15 Mrad or more, whiteness is reduced, and quality is deteriorated.

The electron beam irradiation method may be any of a scanning method, a curtain beam method, a broad beam method, etc., and an accelerating voltage for irradiating an electron beam is 1
A value of 00 KV to 300 KV is suitable.

[0022]

EXAMPLES Examples of the present invention will be described below. In the examples, "parts" and "%" indicate parts by weight and% by weight, unless otherwise specified.

Example 1 (Solution A) Crystal Violet Lactone 10 parts Polyvinyl alcohol (5% aqueous solution) 10 parts (Saponification degree 98 mol%, degree of polymerization 1100) Water 15 parts (Solution B) Bisphenol A 50 parts Polyvinyl alcohol ( 5% aqueous solution) 50 parts Water 75 parts Liquid A and liquid B are separately separated with a sand grinder to have an average particle size of 3
Grind to about μm, then liquid A, liquid B, CaC
0 ₃ 25 parts, 25 parts of silica, a mixture of 15% aqueous solution of 270 parts of the same polyvinyl alcohol as that used in each liquid, coating amount after drying the coating liquid to the paper based on the basis weight 50 g / m ² is It was coated at 5.0 g / m ² and dried to obtain a thermosensitive recording paper.

On the recording layer of this heat-sensitive recording paper, an overcoat coating liquid having the following composition was applied at a dry weight of 5.0 g / m ^2.
The coating solution was applied so that the irradiation amount was 5 Mrad, and then dried. [Coating liquid for overcoat] Calcium carbonate (Softon 1200, Bihoku Powder Co., Ltd.) 100 parts Polyvinyl alcohol containing acetoacetyl group 100 parts (Z-200, manufactured by Nippon Synthetic Chemical Industry) Water resistance, oil resistance, and resistance of such thermal recording paper. A quality test was conducted for plasticizer resistance and solvent resistance. The results are shown in Table 1.

Example 2 In Example 1, the composition coated on the recording layer of the thermosensitive recording paper was changed to the following composition, and the overcoat coating liquid was dried at 5 parts by weight.
It was applied so as to have a concentration of g / m ² , irradiated with an irradiation dose of 2 Mrad, and then dried. [Coating liquid for overcoat] Kaolin (UW-90, manufactured by EMC Co.) 100 parts Polyvinyl alcohol (P-110, manufactured by Kuraray Co., Ltd.) 50 parts Oligoester acrylate emulsion 50 parts (trade name "Aronix M-, manufactured by Toagosei Co., Ltd." Emulsion of "8060") A quality test was conducted on the heat-sensitive recording paper for water resistance, oil resistance, plasticizer resistance, and solvent resistance. The results are shown in Table 1.

Comparative Examples 1 and 2 Water resistance and oil resistance of the heat-sensitive recording paper provided with the overcoat layer in Examples 1 and 2 without being irradiated with an electron beam.
A quality test was conducted for plasticizer resistance and solvent resistance. The results are shown in Table 1.

Comparative Example 3 In Example 1, a quality test was carried out for water resistance, oil resistance, plasticizer resistance, and solvent resistance of the thermosensitive recording paper to which the overcoat coating liquid was not applied, without being irradiated with an electron beam. I went. The results are shown in Table 1.

[0028]

[Table 1]

Note 1) is a facsimile (Mitsubishi "ME
LFAX-550 ") was used to develop a grid pattern, and the value 2) measured with a Macbeth densitometer of the color development part was 2), and the background density of the non-color development part of the grid pattern of 1) was 3) with a Macbeth densitometer. The heat-sensitive recording paper on which the print color was developed was immersed in water for 5 minutes and then rubbed back and forth with gauze, and the density of the print area was measured. 4) Drop a few drops of edible soybean oil on the printed color part.
After the minutes, soybean oil was extracted with gauze, and the density of the printed portion was measured. In 5), the heat-sensitive recording paper on which color was printed was sandwiched between two vinyl chloride wrap films (manufactured by Mitsui Toatsu), and the print density after 24 hours was measured. In 6), several drops of methyl ethyl ketone were dropped on the background, and 1 minute later, the methyl ethyl ketone was extracted with gauze, and then the color density of the background was measured.

[0030]

According to the present invention, even if water adheres to the recorded thermosensitive recording medium, or even if it is placed in an atmosphere of high humidity, the recording density is lowered or the recorded image portion is not printed. Even if it is rubbed with clothes or clothes, the recorded image does not fall off,
There is an advantage that a heat-sensitive recording material excellent in storage stability can be obtained.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hironori Fujioka 4-3-1 Jokoji, Amagasaki, Hyogo Prefecture In the factory (56) Reference JP-A-58-177392 (JP, A)

Claims (1)

[Claims] 1. A coating material for a thermosensitive recording medium comprising a color former, a color former, and a water-soluble and / or water-dispersible adhesive as a main component is applied to a support and dried, and then the coated surface is ethylenic. A water-soluble adhesive that does not have an unsaturated bond or an ethylenically unsaturated bond
A method for producing a heat-sensitive recording material, which comprises irradiating an electron beam after applying a water-soluble adhesive having no compatibility and an electron beam curable resin emulsion.