JP2005104134A - Heat-sensitive recording medium and novel developer compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat-sensitive recording medium with high sensitivity whose whiteness degree is high, in which the color development at a white paper part does not occur even in a high-temperature environment of a simulation such as the inside of an automobile under the blazing sun in summer and heating cooking with a microwave oven in environment resistant tests, and which is excellent in preservability for a long period of time of a color developed image such as oil resistance and plasticizer resistance. <P>SOLUTION: The heat-sensitive recording medium has a sheet-like base body and a heat-sensitive color developing layer which is formed at least to one face of the sheet-like base body and includes a colorless or pale-color dye precursor and a developer for developing the color of the dye precursor through a chemical reaction with the dye precursor under heating. The heat-sensitive recording medium is characterized in that the developer includes at least one kind of compound represented by general formula (I). However, in formula (I), R<SP>1</SP>represents an un-substituted aromatic group or an aromatic group substituted by at least one member selected from a methyl group and a chlorine atom and R<SP>2</SP>represents a bivalent organic group. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a heat-sensitive recording material that forms a color image by heating. More specifically, the present invention relates to a heat-sensitive recording material having high whiteness, no disappearance of a once-colored image, excellent recording storage stability, and high recording sensitivity. The heat-sensitive recording material of the present invention has good long-term storage stability of the recording, and at the same time has excellent heat resistance, moisture resistance and other environmental resistance of the recorded image, oil resistance, plasticizer resistance, and recording sensitivity and whiteness. The present invention relates to a thermal recording medium that is useful for image recording paper, cash dispenser paper, boarding tickets, commuter passes, labels such as POS labels, cards such as prepaid cards, and traffic tickets.

  The heat-sensitive recording material is generally a color developing material such as an electron donating leuco dye and a color developing material such as an organic acid material such as an electron accepting phenolic compound on a support such as paper, synthetic paper or plastic film. Is provided as a main component, and a recorded image can be obtained by reacting them with heat energy. Such thermal recording materials are disclosed in Japanese Patent Publication No. 43-4160, Japanese Patent Publication No. 45-14039, Japanese Patent Publication No. 48-27736, etc., and are widely put into practical use.

  The thermal recording medium is compact, inexpensive, and easy to maintain, so it can be used in a wide range of electronic computer outputs, facsimiles, automatic ticket vending machines, scientific instrument printers, or CRT medical instrument printers. in use. However, in a conventional so-called dye-type thermosensitive recording material in which a color-forming dye substance, a color developing substance and a binder are coated on a support as an active ingredient, the so-called dye-type thermosensitive recording medium has a reversible color reaction. For this reason, it is known that a color-development image is erased over time. This decolorization is accelerated under exposure, high humidity, and high temperature atmosphere, and further progresses by leaving it in water for a long time, contact with oil such as salad oil, and plasticizer, and the image is unreadable. It will disappear.

  On the other hand, since the dye-type thermosensitive recording medium undergoes a color development reaction upon heating, spontaneous color development (referred to as ground color development) occurs when held in a high-temperature and high-humidity atmosphere, resulting in poor contrast. It is also known that recorded images are difficult to distinguish. In particular, thermal recording type parking tickets and toll tickets left in cars under the hot summer weather, or thermal recording type POS labels heated by microwave ovens with supermarkets and convenience store side dishes and lunch boxes, Coloring occurs and the recorded image becomes unreadable.

  Numerous techniques have been disclosed to suppress this decoloring phenomenon while using a coloring system that uses dyes mainly composed of colorless or light-colored lactone ring compounds. For example, phenolic antioxidants such as those disclosed in JP-A-60-78782, JP-A-59-167292, JP-A-59-114096, and JP-A-59-93387 are treated with a thermosensitive coloring layer. Ingredients blended therein, or those using a hydrophobic polymer compound emulsion or the like as disclosed in JP-A-56-146996 as a protective layer, or as seen in JP-A-58-199189 In addition, a water-soluble polymer compound or a hydrophobic polymer compound emulsion is provided as an intermediate layer on the thermosensitive coloring layer, and a surface layer made of an oil-based paint using the hydrophobic polymer compound as a resin component is provided thereon. A combination of a phenolic developer and an epoxy compound as disclosed in JP-A 62-164579, and further in JP-A 62-169681 Such as those using a metal salt of a specific salicylic acid derivative as a color-developing agent is disclosed to be. However, in many cases, there is almost no improvement effect, or some improvement effect is recognized, but it takes a long time to appear, or the effect does not last for a long time. The performance is not satisfactory. In addition, there are cases in which adverse effects such as high-temperature / high-humidity color development and reduced recording sensitivity are unavoidable due to the improved operation, and practical proposals have been awaited for a long time.

  Moreover, as a measure completely different from the above, a technique is disclosed in which a sulfonylurea compound is used as a developer in place of a conventional organic acidic compound typified by phenol (see, for example, Patent Documents 1 and 2). ). The proposal to use a sulfonylurea compound as a developer is very innovative and not only created a new coloring functional group, but also not only under various environmental conditions such as high temperature and high humidity, but also in the past. Succeeded in completely suppressing even the recorded image decoloring phenomenon in contact with oil and plasticizer, which was considered impossible, and completed the thermal recording material with extremely high storage stability of recorded images. I let you.

However, even with the above sulfonylurea developer, the recorded image storage stability of the thermal recording material has been dramatically improved, so that when it is held under high temperature and high humidity, which is another disadvantage of the thermal recording material, ground color development occurs. As a result, the phenomenon that the contrast deteriorates and the recorded image becomes difficult to read has been strongly desired to improve this phenomenon at an early stage. In other words, although the proposal to use the sulfonylurea compound as a developer is effective in improving the storage stability of recorded images, it suppresses ground color development under more severe environmental conditions as required recently. By the time, it did not necessarily reach.
Further, a sulfonylurea developer similar to the chemical structure of the present invention (see, for example, Patent Document 3) has been proposed, but this is also required recently even though it is effective in improving the recording image storage stability. It cannot be said that it is sufficient to suppress the color development under such severe environmental conditions.

  Because the thermal recording medium develops color when heated, it is unavoidable that the background color develops in a high temperature environment. However, the improvement of the developer and sensitizer makes it possible to reduce the level to a lower level. (For example, see Patent Document 4). In recent years, however, even in harsher environments than ever, for example, when a heat-sensitive parking ticket or toll ticket is left in a car under the hot summer weather, or it is affixed to a side dish or lunch box at a supermarket or convenience store. Even when the thermal recording type POS label is heated by a microwave oven, the thermal paper is required to have a performance that allows the recorded image to be read with good contrast without causing background coloring. It can be said that it has been greeted.

One proposal to meet these requirements is to use a compound having a relatively large molecular weight as a developer, but this proposal also has a low recorded image to some extent and cannot be used practically (for example, patents). Reference 5).
Thus, a thermal recording material that has both the storage stability of a recorded image and the ability to suppress background color development in a harsher environment and has sufficient basic performance in practical use has not yet been proposed.

JP-A-5-147357 (2nd page) JP-A-5-32601 (page 2-4) JP 2000-355578 A (page 2-8) JP-A-6-1069 (page 2) JP-A-8-333329 (2nd page)

  The present invention solves these problems, the whiteness of the thermal paper is high, and in the environmental resistance test, particularly in a car under summer hot weather or even in a high temperature environment assuming cooking by a microwave oven Therefore, it is an object of the present invention to provide a high-sensitivity heat-sensitive recording material in which the color development of the color image is suppressed, the recorded image is not decolored, and the color image has excellent long-term storage stability such as oil resistance and plasticizer resistance. The present invention can be used as, for example, a highway freeway ticket or a thermal recording ticket for an automatic ticket vending machine, a parking ticket entrance ticket, as well as a coupon ticket or commuter pass that requires preservation, Provided is a thermal recording material suitable as a label for a bar code system for POS to be attached to a packaging surface of a food packaged with a polychlorinated film that cannot be contacted with a plasticizer and oil.

（ただし、式（Ｉ）において、Ｒ¹は無置換の芳香族基、あるいは、メチル基及び塩素原子から選ばれた少なくとも一員により置換された芳香族基を表し、Ｒ²は２価の有機基を表す。）により表される少なくとも１種の化合物を含むことを特徴とする感熱記録体。
［２］前記式（Ｉ）において、Ｒ²により表される２価の有機基が、−（ＣＨ₂）ｍ−基、及び−（ＣＨ₂ＣＨ₂Ｏ）ｎ−ＣＨ₂ＣＨ₂−基（但し、ｍは、１〜３０の整数を表し、ｎは１〜２０の整数を表す）から選ばれる、[１]項に記載の感熱記録体。
［３］下記化学式（II）

により表される１，５−（３−オキソペンチレン） ビス（３−（３’−(ｐ−トルエンスルホニル)ウレイド）ベンゾエート）。
［４］下記化学式（III）

により表される１，５−ペンタメチレン ビス（３−（３’−(ｐ−トルエンスルホニル)ウレイド）ベンゾエート）。
［５］下記化学式（ＩＶ）

により表される１，６−ヘキサメチレン ビス（３−（３'−（ｐ−トルエンスルホニル）ウレイド）ベンゾエート）。 In order to solve the above problems, the present invention adopts the following configuration.
[1] A sheet-like substrate, a colorless or light-colored dye precursor formed on at least one surface of the sheet-like substrate, and a developer that reacts with the dye precursor under heating to develop color. A heat-sensitive color developing layer, and the developer is represented by the following general formula (I)

(In the formula (I), R ¹ represents an unsubstituted aromatic group or an aromatic group substituted with at least one member selected from a methyl group and a chlorine atom, and R ² represents a divalent organic group. A heat-sensitive recording material comprising at least one compound represented by the formula:
[2] In the formula (I), the divalent organic group represented by R ² is a — (CH ₂ ) m— group and a — (CH ₂ CH ₂ O) n—CH ₂ CH ₂ — group ( However, m represents the integer of 1-30, n represents the integer of 1-20), The heat-sensitive recording material as described in the item [1].
[3] The following chemical formula (II)

1,5- (3-oxopentylene) bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate) represented by:
[4] The following chemical formula (III)

1,5-pentamethylene bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate) represented by
[5] The following chemical formula (IV)

1,6-hexamethylene bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate) represented by:

The heat-sensitive recording material of the present invention uses the aromatic compound represented by the general formula (I) as a developer in the heat-sensitive color developing layer, and therefore exhibits high whiteness and high color development performance. In addition, it hardly causes background coloration even in a high temperature and high humidity atmosphere, particularly in a car under summer hot weather, or in a severe environment corresponding to cooking by a microwave oven, and exhibits high color image storage stability.
The heat-sensitive recording material of the present invention using the aromatic compound represented by the general formula (I) as the developer in the heat-sensitive color developing layer has a very high color image storage stability even when it is in contact with a plasticizer or a vinyl chloride film. Indicates.

  The compound of the formula (I) used in the present invention acts as a developer. That is, the compound of the formula (I) does not have an acidic functional group such as a phenolic hydroxyl group or a carboxyl group, but has a strong color developing ability with respect to a basic leuco dye. This is understood because the urea group in the compound of formula (I) is activated by the sulfonyl group adjacent thereto.

The R ¹ group in the general formula (I) represents an unsubstituted aromatic group or an aromatic group substituted with at least one member selected from a methyl group and a chlorine atom, specifically, a phenyl group , 2-naphthyl group, p-tolyl group, o-tolyl group, m-tolyl group, p-chlorophenyl group and the like.

Further, the R ² group in the general formula (I) is not particularly limited as long as it is a divalent organic group, but a member selected from the following groups (a), (b), and (c) is desirable.
(A) A divalent group formed by removing two hydrogens from a chain or cyclic aliphatic hydrocarbon, particularly a — (CH ₂ ) m-group (m = 1 to 30).
Specifically, a methylene group, a dimethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, or a 1-methyl-1,3-trimethylene group having a substituent in the side chain, 2,3-dimethyl Examples include -1,4-tetramethylene group, 1,4-cyclohexyl group, 1,4-cyclohexanedimethylene group and the like.

(B) a divalent group formed by removing two hydrogens from a compound in which a part of a chain or cyclic aliphatic hydrocarbon is substituted with a heteroatom, particularly — (CH ₂ CH ₂ O) n—CH ₂ CH ₂ -group (n = 1-20).
Specifically, 1,5- (3-oxapentylene) group, 1,5- (3-thiopentylene) group, 1,8- (3,6-dioxaoctylene) group, 2,5- ( 1-oxacyclohexylene) group, 1-oxacyclohexane-2,5-dimethylene group and the like.

(C) An aromatic compound substituted with an alkyl group or an alkyl group partially substituted with a hetero atom, and removing two hydrogens from the alkyl group or an alkyl group partially substituted with a hetero atom Divalent group.
Specifically, α, α ′-(p-xylylene) group, α, α ′-(m-xylylene) group, β, β ′-(1,4-di (dimethylene) benzene) group, γ, γ Examples include a '-(1,4-di (dimethylene) benzene) group.

Specific compounds of the developer relating to the present invention are as follows. Examples of compounds of formula (I) include methylene bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate), methylene bis (3- (3 ′-(m-toluenesulfonyl) ureido) benzoate), Methylene bis (3- (3 ′-(o-toluenesulfonyl) ureido) benzoate), 1,2-dimethylene bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate), 1,2-dimethylene bis (3- (3 ′-(m-toluenesulfonyl) ureido) benzoate), 1,2-dimethylene bis (3- (3 ′-(o-toluenesulfonyl) ureido) benzoate), 1,3-trimethylene bis (3 -(3 '-(p-toluenesulfonyl) ureido) benzoate), 1,3-trimethylene bis (3- (3'-(o-toluenesulfonyl)) Ureido) benzoate), 1,3-trimethylene bis (3- (3 ′-(m-toluenesulfonyl) ureido) benzoate), 1,4-tetramethylene bis (3- (3 ′-(p-toluenesulfonyl) ureido) ) Benzoate), 1,4-tetramethylene bis (3- (3 ′-(o-toluenesulfonyl) ureido) benzoate), 1,4-tetramethylene bis (3- (3 ′-(m-toluenesulfonyl) ureido) ) Benzoate), 1,5-pentamethylene bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate), 1,5-pentamethylene bis (3- (3 ′-(m-toluenesulfonyl) ureido) ) Benzoate), 1,5-pentamethylene bis (3- (3 ′-(o-toluenesulfonyl) ureido) benzoate), 1,6- Xamethylene bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate), 1,6-hexamethylene bis (3- (3 ′-(m-toluenesulfonyl) ureido) benzoate), 1,6-hexa Methylene bis (3- (3 ′-(o-toluenesulfonyl) ureido) benzoate), 1,7-heptamethylene bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate), 1,7-hepta Methylene bis (3- (3 ′-(m-toluenesulfonyl) ureido) benzoate), 1,7-heptamethylene bis (3- (3 ′-(o-toluenesulfonyl) ureido) benzoate), 1,8-octa Methylene bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate), 1,8-octamethylene bis (3- (3 ′-(m- Toluenesulfonyl) ureido) benzoate), 1,8-octamethylene bis (3- (3 ′-(o-toluenesulfonyl) ureido) benzoate), 1,9-nonamethylene bis (3- (3 ′-(p-toluene) Sulfonyl) ureido) benzoate), 1,9-nonamethylene bis (3- (3 ′-(m-toluenesulfonyl) ureido) benzoate), 1,9-nonamethylene bis (3- (3 ′-(o-toluenesulfonyl)) Ureido) benzoate), 1-methylethylene bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate), 1-methylethylene bis (3- (3 ′-(o-toluenesulfonyl) ureido) benzoate) 1-methylethylene bis (3- (3 ′-(m-toluenesulfonyl) ureido) benzoate), 1,5- (3- Oxopentylene) bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate), 1,5- (3-oxopentylene) bis (3- (3 ′-(m-toluenesulfonyl) ureido) Benzoate), 1,5- (3-oxopentylene) bis (3- (3 ′-(o-toluenesulfonyl) ureido) benzoate), 1,8- (3,6-dioxaoctylene) bis (3 -(3 '-(p-toluenesulfonyl) ureido) benzoate), 1,8- (3,6-dioxaoctylene) bis (3- (3'-(m-toluenesulfonyl) ureido) benzoate), 1 , 8- (3,6-dioxaoctylene) bis (3- (3 ′-(o-toluenesulfonyl) ureido) benzoate), α, α ′-(1,4-cyclohexanedimethylene) bis (3- (3 '-(p-Torr Sulfonyl) ureido) benzoate), α, α ′-(1,4-cyclohexanedimethylene) bis (3- (3 ′-(o-toluenesulfonyl) ureido) benzoate), α, α ′-(p-xylylene) ) Bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate), α, α ′-(p-xylylene) bis (3- (3 ′-(m-toluenesulfonyl) ureido) benzoate). Among them, 1,5- (3-oxopentylene) bis (3- (3 ′-(p-toluenesulfonyl)) is preferable from the viewpoint of exhibiting particularly excellent image storability while exhibiting excellent color developability. Ureido) benzoate), 1,5-pentamethylene bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate) and 1,6-hexamethylene bis (3- (3 ′-(p-toluenesulfonyl)) Ureido) benzoate) is particularly preferred.
These compounds may be used alone or in combination of two or more thereof.

  Examples of the leuco dye used as the dye precursor in the present invention include triphenylmethane, fluorane, and diphenylmethane compounds, and can be selected from conventionally known ones. For example, 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide, crystal violet lactone, 3- (N-ethyl-N-iso Pentylamino) -6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7- (o, p-dimethylanilino) fluorane 3- (N-ethyl-Np-toluidino) -6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl- 7-anilinofluorane, 3- (N-cyclohexyl-N-methylamino) -6-methyl-7-anilinofluorane, 3-diethylamino-7- (o Chloroanilino) fluorane, 3-diethylamino-7- (o-chloroanilino) fluorane, 3-dibutylamino-7- (m-trifluoromethylanilino) fluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3 -Diethylamino-6-methylfluorane, 3-cyclohexylamino-6-chlorofluorane, and 3- (N-ethyl-N-hexylamino) -6-methyl-7- (p-chloroanilino) fluorane, 3- ( One or more selected from N, N-dipentylamino) -6-methyl-7-anilinofluorane and the like can be used.

  Further, in the present invention, a conventionally known developer comprising a phenol, a developer having one sulfonylurea group in one molecule, or an organic acid within a range not inhibiting the desired effect is represented by the formula ( It can be used in combination with the compound of I). These conventional developers include, for example, 2,2-bis (4-hydroxyphenyl) propane (bisphenol A), 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 1,4-bis ( 1-methyl-1- (4′-hydroxyphenyl) ethyl) benzene, 1,3-bis (1-methyl-1- (4′-hydroxyphenyl) ethyl) benzene, dihydroxydiphenyl ether (Japanese Patent Laid-open No. 1-180382) Benzyl p-hydroxybenzoate (Japanese Patent Laid-Open No. 52-144043), bisphenol S, 4-hydroxy-4'-isopropyloxydiphenyl sulfone (Japanese Patent Laid-Open No. 60-13852), 1,1-di (4 -Hydroxyphenyl) cyclohexane, 1,7-di (4-hydroxyphenylthio) -3,5-dioxahepta (JP 59-52694 A), 3,3′-diallyl-4,4′-dihydroxydiphenyl sulfone (JP 60-208286 A), 2,4-bis (phenylsulfonyl) phenol (JP No. 8-269000).

  Further, as a developer other than phenol, it is disclosed in JP-A-5-32601. For example, N- (p-toluenesulfonyl) -N′-phenylurea, N- (p-toluenesulfonyl) -N ′-(p-methoxyphenyl) urea, N- (p-toluenesulfonyl) -N ′-( o-tolyl) urea, N- (p-toluenesulfonyl) -N ′-(m-tolyl) urea, N- (p-toluenesulfonyl) -N ′-(p-tolyl) urea, N- (p-toluene) Sulfonyl) -N ′-(o-chlorophenyl) urea, N- (benzenesulfonyl) -N′-phenylurea, N- (p-chlorobenzenesulfonyl) -N′-phenylurea and the like.

  Furthermore, in the present invention, a conventionally known heat-fusible substance (sensitizer) can be used in combination as long as the desired effect is not impaired. Typical examples thereof include 1-hydroxy-2-naphthoic acid phenyl ester (Japanese Patent Laid-Open No. 57-91089), p-benzylbiphenyl (Japanese Patent Laid-Open No. 60-82382), benzyl naphthyl ether (specialty). No. 58-87094), dibenzyl terephthalate (Japanese Unexamined Patent Publication No. 58-98285), benzyl p-benzyloxybenzoate (Japanese Unexamined Patent Publication No. 57-201691), diphenyl carbonate, ditolyl carbonate (Japanese Unexamined Patent Publication No. 58-136489), m-terphenyl (Japanese Patent Laid-Open No. 57-89994), 1,2-bis (m-tolyloxy) ethane (Japanese Patent Laid-Open No. 60-56588), 1,5-bis ( p-methoxyphenoxy) -3-oxapentane (Japanese Patent Laid-Open No. 62-181183), oxalic acid diesters (Japanese Patent Laid-Open No. Sho 64-64) 583 JP), 1,4-bis (p- tolyloxy) and the like benzene (JP-A-2-153783).

  The heat-sensitive coloring layer of the heat-sensitive recording material of the present invention can further contain waxes, and preferably contains organic or inorganic pigments. The thermosensitive coloring layer further contains a binder for fixing these components to the support.

  The content of the leuco dye in the heat-sensitive color developing layer in the heat-sensitive color developing layer is generally preferably 5 to 20% by mass of the dry weight of the heat sensitive color developing layer, and the content of the novel developer of the present invention is generally 5 to 5% by mass. It is preferable that it is 50 mass%. If the content is less than 5% by mass, the developing ability may be insufficient, and even if it exceeds 50% by mass, the developing ability is saturated and no particular improvement is seen, which may be economically disadvantageous. is there. Further, when using a sensitizer, the addition of less than 5% may result in insufficient sensitization effect, and even if added over 50% by mass, the sensitization effect is saturated and further increase in sensitivity cannot be expected.

  When the heat-sensitive color developing layer contains a conventionally known phenol-based or organic acid-based developer, the content is preferably 5 to 40% by mass. When a sensitizer is used, the content is 10%. -40 mass% is preferable. When waxes and white pigments are contained in the thermosensitive coloring layer, the content is preferably 2 to 20% by mass and 2 to 50% by mass, respectively, and the content of the binder is generally 5 to 20% by mass. .

Examples of the organic or inorganic pigment include calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, calcined clay, talc, and surface-treated calcium carbonate and silica. In addition to these inorganic fine powders, organic fine powders such as urea-formalin resin, styrene / methacrylic acid copolymer, and polystyrene resin can be used.
Examples of waxes that can be used include known paraffins, amide waxes, bisimide waxes, and higher fatty acid metal salts.

  For the binder, polyvinyl alcohols of various molecular weights, starch and derivatives thereof, cellulose derivatives such as methoxycellulose, carboxymethylcellulose, methylcellulose, and ethylcellulose, polyacrylic acid soda, polyvinylpyrrolidone, acrylic acid amide / acrylic acid ester copolymer, Water-soluble polymer materials such as acrylic acid amide / acrylic acid ester / methacrylic acid terpolymer, styrene / maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, and casein, and polyvinyl acetate , Polyurethane, styrene / butadiene copolymer, polyacrylic acid, polyacrylate ester, vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate, ethylene / vinyl acetate copolymer , And it can be used styrene / butadiene / each latexes such as the acrylic copolymer.

The sheet-like substrate used in the heat-sensitive recording material of the present invention is made of paper (including acidic papermaking paper and neutral papermaking paper), coated paper coated with pigment, latex, etc. on the surface, laminated paper, and polyolefin resin. You can choose from synthetic paper, plastic film, etc. On at least one surface of such a sheet-like substrate, a coating solution containing the mixture of the required components is applied and dried to produce a heat-sensitive recording material. The coating amount is preferably from 1 to 15 g / m ² in a state where the coating liquid layer has dried, 2 to 10 g / m ² is particularly preferred.

  In the thermosensitive recording material of the present invention, a coating layer such as a protective layer or a printing layer can be further formed on the thermosensitive coloring layer. Further, an undercoat layer containing a pigment (preferably an oil-absorbing pigment) and an adhesive may be provided between the coating layers as a support.

Hereinafter, the present invention will be specifically described with reference to examples.
Unless otherwise specified, “parts” and “%” represent “parts by mass” and “% by mass”, respectively.

<Synthesis Example 1> 1,5- (3-oxopentylene) bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate)
(1) Synthesis of raw material 1,5- (3-oxopentylene) bis (3-aminobenzoate) In a three-necked flask equipped with a thermometer, a reflux tube and a dropping funnel, 9.84 g of 3-aminobenzoic acid and 120 ml Of N, N-dimethylformamide (dehydrated) was added and 9.96 g of potassium carbonate (anhydrous) was added to the solution. While stirring this mixture with a magnetic stirrer, 5.16 g of bis (2-chloroethyl) ether was added at room temperature. The reaction suspension was stirred at room temperature, heated to reflux at 130 ° C. for 4 hours, then cooled to room temperature, the reaction suspension was added to 300 ml of water, and vigorously stirred to precipitate a white solid. By filtering the aqueous suspension, 10.5 g of 1,5- (3-oxopentylene) bis (3-aminobenzoate) white solid was obtained.
The obtained white solid was confirmed to be the target product by various instrumental analysis including DSC, NMR, IR analysis and the like.

(2) Synthesis of 1,5- (3-oxopentylene) bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate) In a three-necked flask equipped with a dropping funnel, a thermometer and a reflux condenser, .5 g of 1,5- (3-oxopentylene) bis (3-aminobenzoate) was added, and 200 ml of acetonitrile was added thereto and stirred to dissolve. While stirring this mixed solution with a magnetic stirrer, 13.8 g of p-toluenesulfonyl isocyanate was added dropwise at room temperature from a dropping funnel. As the reaction mixture continued to stir, a large amount of white solid precipitated. The reaction mixture was heated at 80 ° C. for 4 hours, cooled and filtered to give 19.5 g of white crystals.

The analysis value of this white crystal is as follows.
Melting point (from DSC): 139.8 ° C
Results of NMR measurement (in DMSO) (numbers are in ppm)
δ = 2.36 (s, 6H), 3.77 (t, 4H), 4.36 (t, 4H), 7.32 (t, 2H), 7.41 (d, 4H), 7.52 -7.54 (m, 4H), 7.83 (d, 4H), 7.98 (t, 2H)
In addition, a peak that may be attributed to NH appeared near δ = 9.07, 10.85.

<Synthesis Example 2> 1,5-pentamethylene bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate (1) Synthesis of raw material 1,5-pentamethylene bis (3-aminobenzoate) Thermometer, In a three-necked flask equipped with a reflux tube and a dropping funnel, 8.20 g of 3-aminobenzoic acid and 100 ml of N, N-dimethylformamide (dehydrated) were placed, and 8.30 g of potassium carbonate (anhydrous) was added to the solution. While stirring the mixture with a magnetic stirrer, 6.85 g of 1,5-dibromopentane was added at room temperature, and the reaction suspension was stirred at room temperature and then heated to reflux at 130 ° C. for 4 hours. The reaction suspension was then cooled to room temperature, the reaction suspension was added to 300 ml of water and stirred vigorously, and the suspension was extracted with 150 ml of ethyl acetate and the solvent was distilled off to remove 9. 75 g of 1,5-pentamethylene bis (3-aminobenzoate) was obtained as an oily product, and the obtained oily product was confirmed to be the target product by various instrumental analysis including NMR, IR analysis, etc. did.

(2) Synthesis of 1,5-pentamethylene bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate) Into a three-necked flask equipped with a dropping funnel, a thermometer and a reflux condenser, 9.75 g of 1, 5-Pentamethylene bis (3-aminobenzoate) was added, and 200 ml of acetonitrile was added thereto and stirred to dissolve. While stirring this mixed solution with a magnetic stirrer, 12.7 g of p-toluenesulfonyl isocyanate was added dropwise at room temperature from a dropping funnel. As the reaction mixture continued to stir, a large amount of white solid precipitated. The reaction mixture was heated at 80 ° C. for 4 hours, cooled and filtered to obtain 19.8 g of white crystals.

The analysis value of this white crystal is as follows.
Melting point: 116-124 ° C
Results of NMR measurement (in DMSO) (numbers are in ppm)
δ = 1.50 (d, 2H), 1.74 (t, 4H), 2.36 (s, 6H), 4.26 (t, 4H), 7.36 (t, 4H), 7.40 (D, 2H), 7.56 (t, 4H), 7.84 (d, 4H), 7.99 (d, 2H)
In addition, peaks that may be attributed to NH appeared near δ = 9.08 and 10.74.

Synthesis Example 3 Synthesis of 1,6-hexamethylene bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate (1) raw material 1,6-hexamethylene bis (3-aminobenzoate) Thermometer, In a three-necked flask equipped with a reflux tube and a dropping funnel, 9.67 g of 3-aminobenzoic acid and 100 ml of N, N-dimethylformamide (dehydrated) were placed, and 9.74 g of potassium carbonate (anhydrous) was added to the solution. While stirring the mixture with a magnetic stirrer, 8.61 g of 1,6-dibromohexane was added at room temperature, and the reaction suspension was stirred at room temperature and then heated to reflux at 130 ° C. for 4 hours. Then, the reaction suspension was cooled to room temperature, the reaction suspension was added to 300 ml of water and stirred vigorously, and the suspension was extracted with 150 ml of ethyl acetate and evaporated to remove 10 0.7 g of 1,6-hexamethylene bis (3-aminobenzoate) was obtained as a white solid, and the obtained white solid was confirmed to be the target product by various instrumental analysis including DSC, NMR, IR analysis, etc. confirmed.

(2) Synthesis of 1,6-hexamethylene bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate) To a three-necked flask equipped with a dropping funnel, a thermometer and a reflux condenser, 10.70 g of 1, 6-Hexamethylene bis (3-aminobenzoate) was added, and 200 ml of acetonitrile was added thereto and stirred to dissolve. While stirring this mixed solution with a magnetic stirrer, 13.8 g of p-toluenesulfonyl isocyanate was added dropwise at room temperature from a dropping funnel. As the reaction mixture continued to stir, a large amount of white solid precipitated. The reaction mixture was heated at 80 ° C. for 4 hours, cooled and filtered to give 20.24 g of white crystals.

The analysis value of this white crystal is as follows.
Melting point: 125 ° C
Results of NMR measurement (in DMSO) (numbers are in ppm)
δ = 1.45 (s, 4H), 1.72 (s, 4H), 2.39 (s, 6H), 4.26 (t, 4H), 7.38 (t, 4H), 7.43 (D, 2H), 7.86 (d, 4H), 8.02 (d, 2H)
In addition, peaks that may be attributed to NH appeared near δ = 9.08, 10.78.
Synthesis Example 4 Synthesis of 1,4-tetramethylene bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate (1) raw material 1,4-tetramethylene bis (3-aminobenzoate) Thermometer, Into a three-necked flask equipped with a reflux tube and a dropping funnel, 9.64 g of 3-aminobenzoic acid and 100 ml of N, N-dimethylformamide (dehydrated) were placed, and 9.71 g of potassium carbonate (anhydrous) was added to the solution. While stirring the mixture with a magnetic stirrer, 7.60 g of 1,4-dibromobutane was added at room temperature, and the reaction suspension was stirred at room temperature and then heated to reflux at 130 ° C. for 4 hours. The reaction suspension was then cooled to room temperature, the reaction suspension was added to 300 ml of water and stirred vigorously, and the suspension was extracted with 150 ml of ethyl acetate and the solvent was distilled off to remove 9.6. 0 g of 1,4-tetramethylene bis (3-aminobenzoate) was obtained as a white solid, and the obtained white solid was confirmed to be the target product by various instrumental analysis including DSC, NMR, IR analysis, etc. did.

(2) Synthesis of 1,4-tetramethylene bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate) Into a three-necked flask equipped with a dropping funnel, a thermometer and a reflux condenser, 9.60 g of 1, 4-Tetramethylene bis (3-aminobenzoate) was added, and 200 ml of acetonitrile was added thereto and stirred to dissolve. While stirring this mixed solution with a magnetic stirrer, 13.6 g of p-toluenesulfonyl isocyanate was added dropwise from a dropping funnel at room temperature. As the reaction mixture continued to stir, a large amount of white solid precipitated. The reaction mixture was heated at 80 ° C. for 4 hours, cooled and filtered to give 20.1 g of white crystals.

The analysis value of this white crystal is as follows.
Melting point: 159 ° C
Results of NMR measurement (in DMSO) (numbers are in ppm)
δ = 1.83 (s, 4H), 2.38 (s, 6H), 4.31 (t, 4H), 7.39 (d, 4H), 7.42 (d, 2H), 7.57 (T, 4H), 7.85 (d, 4), 8.00 (d, 2H)
In addition, peaks that may be attributed to NH appeared near δ = 9.07 and 10.76.

Example 1
A thermal recording paper was prepared by the following operation.
(1) Preparation of pigment undercoat paper A styrene-butadiene copolymer emulsion (solid content 50%) was prepared by dispersing 85 parts of calcined clay (trade name Ancilex: manufactured by Engerhard) in 320 parts of water. A coating solution obtained by mixing 40 parts of a 10% aqueous solution of 10% oxidized starch was coated on a 48 g / m ² base paper so that the coating amount after drying was 7.0 g / m ^2. A pigment-primed paper was obtained.

(2) Preparation of dispersion A
Components
3- (N, N-dibutylamino) -6
Methyl-7-anilinofluorane 20
Polyvinyl alcohol 10% aqueous solution 10
Water 70
The composition was pulverized using a sand grinder until the average particle size became 1 μm or less.

(3) Preparation of dispersion B
Components
1,5- (3-oxopentylene) bis (3- (3 ′-(p-toluenesulfonyl)
Ureido) Benzoate) 20
Polyvinyl alcohol 10% aqueous solution 10
Water 70
The composition was pulverized using a sand grinder until the average particle size became 1 μm or less.

(4) Preparation of dispersion C
Components
Oxalic acid di p-methylbenzyl ester 20
Polyvinyl alcohol 10% aqueous solution 10
Water 70
The composition was pulverized using a sand grinder until the average particle size became 1 μm or less.

(5) Formation of coloring layer 60 parts A, 120 parts B, 120 parts C, 23 parts kaolinite pigment (trade name: HG clay, manufactured by Huber), 20 parts 25% zinc stearate dispersion, 15 parts of 30% paraffin dispersion and 120 parts of 10% polyvinyl alcohol aqueous solution were mixed and stirred to obtain a coating solution. This coating solution was applied and dried on one side of the pigment undercoat paper so that the coating amount after drying was 5.0 g / m ² to form a thermosensitive coloring layer, and a thermosensitive recording paper was prepared.

(6) Supercalender treatment The thermal recording paper obtained as described above was treated with a supercalender, and the surface smoothness was set to 800 to 1000 seconds.

(7) Various tests (a) Whiteness About the said thermosensitive recording paper sample, the whiteness was measured using the Hunter whiteness meter (made by Toyo Seiki Seisakusho).

(B) Color development test The thermal recording material obtained in this way was checked using a dynamic thermal color development simulator THPMD (printing voltage 21.7 V) manufactured by Okura Electric Co., Ltd. under a printing condition with an applied pulse width of 0.7 ms and 1.0 ms. Colored in a pattern. The color density was measured with a Macbeth reflection densitometer RD-914, and this was a value representative of recording sensitivity.

(C) White Paper Part Wet-proof Color Development Test The thermosensitive recording paper sample was placed in a thermo-hygrostat adjusted to 40 ° C. and 90% for 24 hours, and the density of the white paper part was measured in the same manner as in (b) above.

(D) White paper portion heat resistant ground color development test The above-mentioned thermal recording paper sample was placed in a thermostat at 60 ° C. for 24 hours, and the density of the white paper portion was measured in the same manner as in (b) above.

Example 2
The same operation as in Example 1 was performed. However, in the preparation of Dispersion B, 1,5-pentamethylene bis (instead of 1,5- (3-oxopentylene) bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate) 3- (3 ′-(p-toluenesulfonyl) ureido) benzoate) was used. The test results are shown in Table 1.

Example 3
The same operation as in Example 1 was performed. However, in the preparation of the dispersion B, 1,3-trimethylene bis (3) was used instead of 1,5- (3-oxopentylene) bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate). -(3 '-(p-toluenesulfonyl) ureido) benzoate) was used. The test results are shown in Table 1.

Example 4
The same operation as in Example 1 was performed. However, in preparing dispersion B, 1,8- (3,6 instead of 1,5- (3-oxopentylene) bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate) -Dioxaoctylene) bis (3- (3 '-(p-toluenesulfonyl) ureido) benzoate) was used. The test results are shown in Table 1.

Example 5
The same operation as in Example 1 was performed. However, in the preparation of dispersion B, 1,6-hexamethylene bis (instead of 1,5- (3-oxopentylene) bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate) 3- (3 ′-(p-toluenesulfonyl) ureido) benzoate) was used. The test results are shown in Table 1.

Example 6
The same operation as in Example 1 was performed. However, in the preparation of the dispersion B, 1,4-tetramethylene bis (instead of 1,5- (3-oxopentylene) bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate) 3- (3 ′-(p-toluenesulfonyl) ureido) benzoate) was used. The test results are shown in Table 1.

Comparative Example 1
The same operation as in Example 1 was performed. However, in the preparation of dispersion B, 2,2-bis (4-hydroxy) was used instead of 1,5- (3-oxopentylene) bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate). Phenyl) propane (bisphenol A) was used and the test results are shown in Table 1.

  As is apparent from Table 1, the heat-sensitive recording material of the present invention exhibits high whiteness and high color development performance, suppresses white paper color development in a high-temperature and high-humidity atmosphere, and exhibits excellent thermal performance.

Example 7
A thermal recording paper was prepared by the following operation.
(1) Preparation of pigment primer paper Pigment primer paper was prepared in the same manner as in Example 1 (1).
(2) Preparation of dispersion A
Components
3- (N, N-dipentylamino) -6-methyl-7-anilinofluorane
10
Oxalic acid di-p-methylbenzyl ester 8
Oxalic acid di-p-chlorobenzyl ester 2
Polyvinyl alcohol 10% aqueous solution 10
Water 70
The composition was pulverized using a sand grinder until the average particle size became 1 μm or less.

(3) Preparation of dispersion B
Components
1,5- (3-oxopentylene) bis (3- (3 ′-(p-toluenesulfonyl)
Ureido) Benzoate) 20
Polyvinyl alcohol 10% aqueous solution 10
Water 70
The composition was pulverized using a sand grinder until the average particle size became 1 μm or less.

(4) Formation of coloring layer 20 parts of the above-mentioned A liquid, 30 parts of B liquid, 50 parts of 50% kaolinite pigment (trade name: HG clay, manufactured by Huber), 3 parts of 35% zinc stearate dispersion, and 10% 8 parts of an aqueous polyvinyl alcohol solution was mixed and stirred to obtain a coating solution. This coating solution was applied and dried on one side of the pigment undercoat paper so that the coating amount after drying was 5.0 g / m ² to form a thermosensitive coloring layer, and a thermosensitive recording paper was prepared.

(5) Super calender treatment The thermal recording paper obtained as described above was treated with a super calender, and the surface smoothness was set to 800 to 1000 seconds.

(6) Various tests (e) High heat resistant color development test The thermal recording paper obtained as described above was used with a dynamic thermal color development simulator THPMD (printing voltage 21.7 V) manufactured by Okura Electric Co., Ltd., and an applied pulse width of 1.0 ms. The test piece was developed in a checkered pattern under the following printing conditions, placed in a thermostat at 100 ° C. for 1 hour, and then the density of the background was measured with a Macbeth reflection densitometer RD-914.

(F) Plasticizer resistance test Similar to the heat-sensitive recording paper used in the high heat resistant color development test (e), a sample developed in 1.0 ms was subjected to vinyl chloride film (trade name: Hilap KMA-W, manufactured by Mitsui Chemicals). The vinyl chloride film belongs to the group with the highest plasticizer content among the plastic films for packaging) and is sandwiched from above and below, and is left in a thermostat at 40 ° C. for 17 hours under a load of 10 gf / cm ^2. The vinyl chloride film was peeled off and the residual image density was measured with a Macbeth reflection densitometer, and the image storage rate was calculated according to the following formula.
Image storage rate (%) = (density after plasticizer test / original density) × 100
Table 2 shows the test results of the high heat resistant color development test (e) and the plastic resistance test (f).

Example 8
The same operation as in Example 7 was performed. However, in the preparation of Dispersion B, 1,5-pentamethylene bis (instead of 1,5- (3-oxopentylene) bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate) 3- (3 ′-(p-toluenesulfonyl) ureido) benzoate) was used. The test results are shown in Table 2.

Example 9
The same operation as in Example 7 was performed. However, in the preparation of the dispersion B, 1,3-trimethylene bis (3) was used instead of 1,5- (3-oxopentylene) bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate). -(3 '-(p-toluenesulfonyl) ureido) benzoate) was used. The test results are shown in Table 2.

Example 10
The same operation as in Example 7 was performed. However, in preparing dispersion B, 1,8- (3,6 instead of 1,5- (3-oxopentylene) bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate) -Dioxaoctylene) bis (3- (3 '-(p-toluenesulfonyl) ureido) benzoate) was used. The test results are shown in Table 2.

Example 11
The same operation as in Example 7 was performed. However, in the preparation of dispersion B, 1,6-hexamethylene bis (instead of 1,5- (3-oxopentylene) bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate) 3- (3 ′-(p-toluenesulfonyl) ureido) benzoate) was used. The test results are shown in Table 2.

Example 12
The same operation as in Example 7 was performed. However, in the preparation of the dispersion B, 1,4-tetramethylene bis (instead of 1,5- (3-oxopentylene) bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate) 3- (3 ′-(p-toluenesulfonyl) ureido) benzoate) was used. The test results are shown in Table 2.

Comparative Example 2
The same operation as in Example 7 was performed. However, in the preparation of dispersion B, 2,2-bis (4-hydroxy) was used instead of 1,5- (3-oxopentylene) bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate). Phenyl) propane (bisphenol A) was used and the test results are shown in Table 2.

  As shown in Table 2, Comparative Example 2 caused intense ground coloration in a high temperature environment corresponding to a car under summer hot weather, and the recorded image was indistinguishable, whereas the developer of the present invention was used. In Examples 7, 8, 9, 10, 11, and 12, the recorded image can be read satisfactorily. Further, in Comparative Example 2, the recorded image was erased by contact with the vinyl chloride wrap film, making it unreadable, while Examples 7, 8, 9, 10, 11, and 11 using the developer of the present invention were used. No. 12 holds the recorded image and can be easily read.

  The present invention is a heat-sensitive recording material that has no loss of a once-colored image, has excellent recording storage stability, and high recording sensitivity. The heat-sensitive recording material of the present invention has good long-term storability of recording, and at the same time, heat resistance of the recorded image, particularly in a car under summer hot weather, or higher temperature conditions such as cooking by heating in a microwave oven Excellent heat resistance, moisture resistance, and other chemical resistance such as oil resistance and plasticizer resistance, high recording sensitivity and whiteness, cash dispenser paper, boarding ticket, pass ticket, parking It is useful for tickets, admission tickets, commuter passes, labels represented by POS labels, cards represented by prepaid cards, and the like.

Claims (5)

A heat-sensitive coloring layer comprising a sheet-like substrate, a colorless or light-colored dye precursor formed on at least one surface of the sheet-like substrate, and a developer that reacts with the dye precursor under heating to develop color. And the developer is represented by the following general formula (I)

(In the formula (I), R ¹ represents an unsubstituted aromatic group or an aromatic group substituted with at least one member selected from a methyl group and a chlorine atom, and R ² represents a divalent organic group. A heat-sensitive recording material comprising at least one compound represented by the formula: In the formula (I), the divalent organic group represented by R ² is a — (CH ₂ ) m— group and a — (CH ₂ CH ₂ O) n—CH ₂ CH ₂ — group (provided that m Represents an integer of 1 to 30, and n represents an integer of 1 to 20). The following chemical formula (II)

1,5- (3-oxopentylene) bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate) represented by: The following chemical formula (III)

1,5-pentamethylene bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate) represented by The following chemical formula (IV)

1,6-hexamethylene bis (3- (3 ′-(p-toluenesulfonyl) ureido) benzoate) represented by: