JPS62290579A - Heat-sensitive recording material - Google Patents

Abstract

PURPOSE:To improve the storing stability, by containing an aqueous polyester polyurethane resin into one of a heat-sensitive coloring layer or an intermediate layer in a heat-sensitive recording material containing an electron donative component and an electron receiving component. CONSTITUTION:A supporting material, a heat-sensitive coloring layer mainly composed of an electron donative component and an electron receiving layer, and if required, an intermediate layer and a protection layer are laminated in this order. An aqueous polyester polyurethane resin is contained into one of the heatsensitive coloring layer or the intermediate layer. Consequently, excellent water-proof performance and anti-chemical performance can be achieved.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention <Industrial Application Field> The present invention relates to a heat-sensitive recording material, and more specifically, the storage stability of a heat-sensitive recording material containing an electron-donating component and an electron-accepting component. ,
In particular, it relates to heat-sensitive recording materials with improved water resistance, chemical resistance, plasticizer resistance, oil resistance, and durability.

<Prior Art> Generally, heat-sensitive recording materials whose coloring components are a colorless or light-colored leuco dye, that is, an electron-donating component, and a color developer, that is, an electron-accepting component that causes the leuco dye to develop a characteristic color under heat, have not been put to practical use in the past. Compared to other heat-sensitive recording materials, it is widely used as recording paper for computer output, facsimiles, recorders, etc., as well as for tickets, cards, etc., because the color images obtained are very clear. However, if a recording sheet using this heat-sensitive recording material comes into contact with water, plasticizer, oil, etc. for a long period of time, the colored areas will fade, and if it comes into contact with organic solvents, the uncolored areas will develop unnecessary color, and even be damaged. has occurred and improvements are needed.

<Problems to be Solved by the Invention> In view of the above problems, the present invention aims to improve the storage stability of heat-sensitive recording materials that produce colored images by heating, particularly water resistance, chemical resistance, oil resistance, plasticizer resistance, and The purpose is to improve durability.

Means for Solving the Problems> The present invention comprises: (a) a support (b) a thermosensitive coloring layer mainly composed of an electron-donating component and an electron-accepting component (c) an intermediate layer (d) a protective layer if necessary The object of the present invention is to provide a heat-sensitive recording material characterized in that these are layered in the above order, and at least one of the heat-sensitive coloring layer and the intermediate layer contains an aqueous polyester polyurethane resin.

The support referred to in the present invention is a sheet of vinyl chloride resin, polyester resin, polypropylene resin, etc., synthetic paper, laminated paper of synthetic resin and paper, or composite resin sheet with high water resistance, chemical resistance, and durability. A wide range of substrates can be used, such as supports with 30% carbon, paper, and metal foils. Particularly preferred are vinyl chloride resins and polyester resin sheets that exhibit strong binding strength with the aqueous polyester polyurethane resin constituting the present invention. Furthermore, the binding force between the support surface and the thermosensitive coloring layer can be improved by matting the surface of these resin sheets or providing an anchor coat layer. The thermosensitive coloring layer formed on one surface of the support is constructed by dispersing an electron-donating component and an electron-accepting component described below in a binder.

That is, examples of representative electron-donating components include crystal violet lactone, 3-indolino-3-p-dimethylaminophenyl-6-dimethylaminophthalide,
3-diethylamino-7-chlorofluorane, 3-diethylamino-5-methyl-7-t-butylfluorane,
3-diethylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-p-butylanilinofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3-cyclohexylamino −
6-chlorofluorane, 3-diethylamino-6-methyl-7-xylidinofluorane, 3-pyrrolidino-6-
Methyl-7-anilinofluorane, 3-pyrrolidino-7
-cyclohexylaminofluorane, 3-piperidino-
6-methyl-7-toluidinofluorane, 3-pyrrolidino-6-methyl-7-(p-toluidino)fluorane,
Examples include, but are not limited to, 3-piperidino-6-methyl-7-anilinofluorane and 3-diethylamino-7-(m-trifluoromethylanilino)fluorane.

Examples of electron-accepting components include 4-phenylphenol, 4-t-butylphenol, 4-hydroxyacetophenone, α-naphthol, β-naphthol, 2.
2'-dihydroxydiphenyl, 2,2'-methylenebis(4-chlorophenol), 2,2'-methylenebis(4-methyl-6-t-butylphenol), methyl-
4-hydroxybenzoate, benzyl-4-hydroxybenzoate, 4,4'-isopropylidene bis(2
-methylphenol), 4,4°-ethylenebis(2-
methylphenol), 1.1'-bis(4-hydroxyphenyl)-cyclohexane, 4.4'-isopropylidene diphenyl, 4.4'-cyclohexylidene bis(2-isopropylphenol), novolak type phenolic resin, 3 .5-di-α-methylbenzylsalicylic acid, 4-hydroxybenzoic acid ester, bis(4-hydroxyphenyl)acetic acid ester, etc., but in the present invention, 4,4゛-dihydroxyphenylsulfone, 4
Sulfur atom-containing phenol compounds such as -hydroxyphenyl-4'-alkyloxyphenylsulfone derivatives and 1,1'-thiobis(4-hydroxy-6-t-butylphenyl) are preferred because of their higher storage stability. used for.

Various water-based resins can be used as the binder for dispersing the electron-donating component and the electron-accepting component, but in the present invention, it is particularly preferable to use a water-based polyester polyurethane resin as described below. .

The aqueous polyester polyurethane resin of the present invention can be obtained by reacting a polyester polyol obtained by condensing a dicarboxylic acid component and a glycol component with a polyisocyanate compound.

Examples of the dicarboxylic acid component include oxalic acid, malonic acid, dimethylmalonic acid, koha(acid), geltaric acid, adipic acid, trimethyladipic acid, pimelic acid, 2,2-dimethylgeltaric acid, azelaic acid, sebacic acid. , fumaric acid, maleic acid, itaconic acid, l,3-cyclopenkunedicarboxylic acid, l,2-cyclohexanedicarboxylic acid,
l, 3-cyclopenkune dicarboxylic acid, ■, 4-cyclohexane dicarboxylic acid, phthalic acid, terephthalic acid,
Isophthalic acid, 2,5-norbornanedicarboxylic acid,
Examples include 1,4-naphthalic acid, siphenic acid, 4,4'-oxybenzoic acid, diglycolic acid, thiodipropion, and 2,5-naphthalene dicarboxylic acid. These may be acid anhydrides, esters, chlorides, etc.
, for example, dimethyl 1,4-cyclohexanedicarboxylate, methyl 2,6-naphthalene dicarboxylate, dimethyl isophthalate, dimethyl terephthalate, and diphenyl terephthalate.

In addition, examples of glycol components include ethylene glycol,
Propylene glycol, ■, 3-propanediol, 2
．． 4-dimethyl-2-ethylhexane-1,3-diol, 2,2-dimethyl-1,3-propanediol, 2
-ethyl-2-butyl-1,3-propanediol, 2
-ethyl-2-isobutyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol,
■, 5-bentanediol, ■, 6-hexanediol, 2,2.4-trimethyl-1゜6-hexanediol, ■, 2-cyclohexane dimetatool, l, 3-cyclohexane dimetatool, 1.4 -Cyclohexane dimetatool, 2.2,4.4-tetramethyl-1,3-cyclobutanediol, 4,4°-thiodiphenol, 4
．． 4'-methylene diphenol, 4.4'-(norbornylidene) diphenol, 4.4°-dihydroxybiphenol, 0-2m- and p-dihydroxybenzene,
4,4°-isopropylidene diphenol, 4,4'-
Isopropylidene bis(2,6-cyclophenol)
, 2,5-naphthalenediol, p-xylene diol, and the like.

Furthermore, the polyisocyanate compounds used in the present invention include 2,4-tolylene diisocyanate, 2,
6-tolylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 4.4
'-Diphenylmethane diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, trimethylhexamethylene diisocyanate, 1,4-cyclohexylene diisocyanate, 4.4'-dicyclohexylmethane diisocyanate, 3.3° -dimethyl-4,4'-biphenylene diisocyanate, 3,3'-dimethoxy-4
, 4'-biphenylene diisocyanate, 3,3°-dichloro 4,4'-biphenylene diisocyanate, l
, 5-naphthalene diisocyanate, 1,5-tetrahydronaphthalene diisocyanate, and the like.

There is no limit to the polyisocyanate content and carboxyl group content in the aqueous polyester polyurethane resin of the present invention, but if the polyisocyanate content is too high, the adhesion and adhesion to the support will be reduced, and if it is too low, the flexibility of the film will be reduced. Since the properties tend to decrease, the content of the polyurethane segment is preferably 40% by weight or less. In addition, when the carboxyl group content is high, adhesion to the support and coating properties are improved, while
The carboxyl group content is preferably about 0.7 to 5% by weight, since the water resistance of the film decreases, and if it is too low, it becomes difficult to make it water-based (and the stability of the resin decreases).

The resin can be made water-based by introducing a sulfonic acid group, a carboxylic acid, or a carboxylic acid group, but in the heat-sensitive recording material of the present invention, carboxylic acid which has good coating properties and high reactivity with a curing agent is used. Preferably, a base is introduced. The method for introducing the carboxylic acid group includes 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, 2
．． After copolymerizing 2-dimethylolvaleric acid and the like as a glycol component when synthesizing a polyester polyol to obtain a carboxylic acid group-containing polyester polyol, it is reacted with a polyisocyanate compound to obtain an aqueous carboxylic acid group-containing polyester polyurethane resin, Thereafter, an aqueous carboxylic acid group-containing polyester polyurethane can be obtained by neutralizing with an organic amine such as ammonia, trimethylamine, or triethylamine.

Furthermore, in order to further improve the water resistance of this aqueous polyester polyurethane resin film, it can also be used in combination with an aziridine-based crosslinking agent or the like.

The water-based polyester polyurethane resin film obtained in this way not only exhibits remarkable water resistance (but also has remarkable barrier properties against oils, plasticizers, chemicals, etc., and exhibits strong adhesion to synthetic resins). , a highly durable heat-sensitive recording material can be obtained.

As the main component of the binder of the heat-sensitive color forming layer in the present invention, it is preferable to use the water-based polyester polyurethane resin as described above, but in that case, it is also possible to use it in combination with the water-based resin shown below. If the polyester polyurethane resin is not used, the present invention can be carried out using the following aqueous resin alone.

For example, polyvinyl alcohol, starches, hydroxyethylcellulose, gum arabic, polyvinylpyrrolidone, alkali salts of acrylic acid (or methacrylic acid) ester copolymers, alkali salts of styrene/maleic anhydride copolymers, isobutylene/maleic anhydride Applicable to water-soluble polymer compounds such as alkali salts of copolymers and acrylamide copolymers, polymer latexes such as styrene/butadiene copolymers, polyvinyl acetate, and acrylic ester copolymers, and water-based resins such as emulsions. do.

Furthermore, the heat-sensitive coloring layer of the present invention may optionally contain inorganic and organic pigments such as aluminum hydroxide, heavy and light calcium carbonate, titanium oxide, zinc oxide, barium sulfate, silica gel, activated clay, talc, Clay, satin white, kaolinite, calcined kaolinite, diatomaceous earth, synthetic kaolinite, polyolefin particles, polystyrene particles, urea-formalin resin particles, etc., and sensitizers such as stearamide, valmitic acid amide, oleic acid. Amide, lauric acid amide, ethylene bis stearamide, methylene bis stearamide, methylol stearamide, paraffin wax, higher alcohol, higher resin acid, etc. may be added.

A heat-sensitive color forming coating liquid mainly consisting of a binder resin as described above, an electron-donating component consisting of a leuco dye, and an electron-accepting component consisting of an acidic substance is applied to the surface of the support, and dried to form a leuco dye-based heat-sensitive color forming layer. will be established.

If necessary, an intermediate layer is provided on the heat-sensitive coloring layer obtained as described above. In this case, the intermediate layer is for separating the protective layer made of a solvent-based paint and the heat-sensitive coloring layer, and the material used for the intermediate layer is generally known water-soluble resin. In view of solvent resistance and compatibility with the leuco dye-based heat-sensitive coloring layer, it is preferable to use the above-mentioned aqueous polyester polyurethane resin as the main component. The intermediate layer in the present invention may contain additives such as a resin curing agent and a coating property modifier, if necessary.

The intermediate layer may contain, for example, casein, gelatin, polyvinyl alcohol, modified polyvinyl alcohol, polyvinylpyrrolidone, starch, modified starch, isobutylene-anhydrous, in order to modify the paint properties, coating properties, and coating film of the intermediate layer. Maleic acid resin, diisobutylene-maleic anhydride resin, polyacrylamide, modified polyacrylamide,
Methyl vinyl ether, maleic acid copolymer, carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and as a water-soluble emulsion, resins such as vinyl acetate, polystyrene, acrylic ester, vinyl chloride-vinyl acetate copolymer, etc. Can be mixed with polyester polyurethane resin. Furthermore, when the water-based polyester polyurethane resin is not used in the intermediate layer, the various water-soluble resins described above can be used alone. Further, the intermediate layer may contain a curing agent, a surfactant, or an antioxidant, an ultraviolet absorber, etc. in order to improve the light resistance of the heat-sensitive recording material, if necessary.

Furthermore, the protective layer referred to in the present invention is provided on the heat-sensitive recording material to improve water resistance, chemical resistance, abrasion resistance, etc., and to match it with a recording thermal head, and is made of, for example, polyurethane resin, acrylic resin, epoxy resin, etc. Various solvent-type polymers such as , fluorine-based resins, etc. are applicable, but polyurethane resins are especially suitable for use in the present invention in terms of water resistance and abrasion resistance.

The heat-sensitive recording material of the present invention having the above-mentioned structure can be used as is as usual heat-sensitive recording paper for facsimile, or can be punched into desired dimensions to be used as identification cards, driver's licenses, business cards, etc.
It can be used as various personal cards such as membership cards. Furthermore, by providing a magnetic recording layer on the back side of the support (the side opposite to the heat-sensitive coloring layer) constituting the heat-sensitive word recording material of the present invention, it can be used as a heat-sensitive magnetic recording material;
If a separator is attached to the back side via a pressure-sensitive adhesive layer, it can also be used as a heat-sensitive recording material for labels. Furthermore, when used for the personal card, predetermined display items such as company name, cautionary notes, commercials, various marks, patterns, etc. may be printed on the back side in monochrome or color. This expands the range of uses for fashionable cards. For example, it can be applied to various cards for general consumers, such as commemorative cards for leisure facilities such as amusement parks, gift cards for Valentine's Day, birthdays, etc. with messages attached to them.

In this case, printing may be done directly on the back of the support using normal printing means, but it is also possible to first provide a white or colored coating layer on the back of the support and then print the specified display items on top of that. You can.

In addition, when the heat-sensitive recording material of the present invention is applied to cards having a magnetic recording layer, the magnetic recording layer is γ-Fe2O.
3. Uniformly disperse a ferromagnetic material such as barium ferrite or strontium ferrite and a binder such as polyester resin, vinyl chloride resin, or polyurethane resin in a solvent such as toluene or methyl ethyl ketone, apply this to the back side of the support, and dry. It is formed by

In this case, in order to prevent troubles in which information recorded on the magnetic recording layer is erased or attenuated due to contact with products using permanent magnets such as handbag clasps, toys, and magnetic necklaces, the present invention uses As the ferromagnetic material, it is preferable to use a material having a high coercive force of 1,500 to 5,000 oersteds, such as barium ferrite or strontium ferrite. Furthermore, for the purpose of preventing counterfeiting, a plurality of high permeability magnetic layers such as sendust and permalloy, and further magnetic layers having a low coercive force of about 200 to 1000 millimeters, such as iron oxide magnetic powder, can be layered.

Further, when the heat-sensitive recording material of the present invention is used as a label having a separator provided thereon via a pressure-sensitive adhesive layer, any material used for conventional release labels can be used for the separator and the pressure-sensitive adhesive layer. For example, as a separator, a release paper obtained by providing a release layer such as a silicone resin on paper, and as a pressure-sensitive adhesive layer, SBR latex, natural rubber latex, rubber emulsion, acrylic emulsion, etc. are applicable to the present invention.

<Examples> The present invention will be explained in detail below using Examples and Comparative Examples. Note that parts in the recipe table represent parts by weight.

A polyester polyurethane resin to be incorporated into the heat-sensitive coloring layer and/or intermediate layer constituting the heat-sensitive recording material of the present invention was synthesized as follows.

83.3 parts of terephthalic acid, 46.5 parts of isophthalic acid in a 500-size flask with stirrer, temperature system, nitrogen blowing device, and packed tower.
After adding 45.6 parts of ethylene glycol, 21.2 parts of diethylene glycol, 0.2 parts of zinc acetate, and 0.4 parts of antimony trioxide and carrying out an esterification reaction at 190 to 220°C for 4 hours, 230 to 250°C, The condensation reaction was carried out under 1 wlIaHg. Furthermore, 44.4 parts of sebacic acid, 2.2
Add 26.8 parts of '-dimethylolpropionic acid to 18
A carboxyl group-containing polyester polyol was obtained by reacting at 0 to 190°C for 200 hours.

After dehydrating 100 parts of this polyester polyol, 130 parts of methyl ethyl ketone was added and dissolved, 15 parts of hexamethylene diisocyanate was added and reacted at 60 to 80°C for 12 hours, neutralized with 25 parts of 10% aqueous ammonia, and further water After dissolving in 560 parts, methyl ethyl ketone was removed under heating and reduced pressure, and then water was added to obtain a polyester polyurethane resin aqueous solution containing 25% carboxylic acid group.

Furthermore, each of the mixtures having the following formulations was ground and dispersed in a ball mill for one day to prepare solutions A to C.

A solution B solution C solution Example 1 10 parts of the above solution A, 33.3 parts of solution B, 49 parts of solution C, 15 parts of the above 25% polyester polyurethane aqueous solution, 46 parts of water
A heat-sensitive recording paint was obtained by mixing the two parts.

After coating and drying the paint on a matte polyester resin sheet with a thickness of 188μ so that the coating amount after drying is 6g/i, a 2μ film of ultraviolet curable ink having the composition shown below is applied. After coating to a thick layer, UV rays were irradiated using an ultraviolet irradiation device (one mercury pump lamp at 1 and 2) at a distance of 110 Cl from the lamp and at a conveyance speed of 15 m/min to form the UV cured protective layer of the present invention. A thermosensitive recording material was obtained.

Solution D Example 2 On the heat-sensitive coloring layer prepared in Example 1, a coating solution E for intermediate layer having the following formulation was prepared, applied and dried to form an intermediate layer.

Liquid E Furthermore, a protective layer coating liquid F liquid having the following formulation was prepared, and the protective layer was formed by coating and drying the liquid on the intermediate layer, thereby producing the heat-sensitive recording material of the present invention.

Solution F Example 3 The electron-accepting component bis(4-hydroxyphenyl)acetic acid methyl ester in Solution B in Example 1 was changed to 4-hydroxyphenyl-4'-propoxyphenylsulfone, which is a phenolic compound containing a sulfur atom. Except for the above, a thermosensitive coloring layer was formed in the same manner as in Example 1, and then an intermediate layer and a protective layer were formed in the same manner as in Example 2 to obtain a thermosensitive recording material of the present invention.

Comparative Example 1 The aqueous polyester polyurethane resin aqueous solution (25%) blended into the heat-sensitive coloring layer and intermediate layer of Example 3,
Sodium sulfonate group-containing polyester resin aqueous solution (
A heat-sensitive recording material was obtained in the same manner as in Example 3, except that 25%) (Eastman WD1 manufactured by Eastman Kodak Company) was used.

The sheet-like heat-sensitive recording materials obtained in the above Examples and Comparative Examples were immersed in water in a water tank, and the period until changes such as formation of blisters and peeling of the protective layer occurred on the surface of the sheet was observed, and the water resistance was evaluated. did. In addition, as a chemical resistance test, methanol was dropped onto the surface of the sheet, and the time required for the methanol to penetrate into the heat-sensitive layer and cause color development was determined. The results are shown in Table 1.

As is clear from Table 1, it was confirmed that the heat-sensitive recording material of the present invention has superior water resistance and chemical resistance as compared to the comparative example based on the prior art.

Further, for the heat-sensitive recording layer of the heat-sensitive recording material of the present invention, a line head type thin film thermal head was used to produce a heat-sensitive recording layer of 0.45 (1 mJ/
When an image was recorded using an energy of 1.21 and the solid black portion was measured using a Macbeth densitometer, a clear colored image of 1.21 was obtained.

<Effects of the Invention> Since the heat-sensitive recording material of the present invention has the above structure, it has extremely excellent water resistance and chemical resistance.

In addition, the heat-sensitive recording material of the present invention has excellent durability with no practical problems even when applied to applications such as cards and labels that require harsh handling and quality compared to ordinary facsimile applications. It was confirmed that

Claims (1)

[Scope of Claims] 1) (a) Support (b) A thermosensitive coloring layer mainly composed of an electron-donating component and an electron-accepting component (c) If necessary, an intermediate layer (d) A protective layer are formed in the above order. , and at least one of the thermosensitive coloring layer and the intermediate layer contains an aqueous polyester polyurethane resin. 2) The heat-sensitive recording material according to item 1, wherein the electron-accepting component is a sulfur atom-containing phenolic compound. 3) The heat-sensitive recording material according to item 1, wherein the aqueous polyester polyurethane resin is an aqueous carboxylic acid group-containing polyester polyurethane resin.