Thermosensitive recording body

Abstract

The present application provides a heat-sensitive recording body having water dispersibility and a heat-sensitive recording label, the heat-sensitive recording label being provided with an adhesive layer on the surface opposite to the surface of a support provided with a heat-sensitive recording layer, the heat-sensitive recording body and the heat-sensitive recording label being excellent in re-printability among various properties required, and being excellent in moisture resistance, plasticizer resistance, solvent resistance, and the like. A heat-sensitive recording body and a heat-sensitive recording label, in a heat-sensitive recording body having a heat-sensitive recording layer containing a non-colored or light-colored electron-donating leuco dye and an electron-accepting color developer on a support, the heat-sensitive recording layer containing at least one urea compound represented by the following general formula (Chemical Formula 1) as the electron-accepting color developer, the support comprising a paper base material having water dispersibility. (In the formula, X represents -O- or -NH-, R 1 represents a hydrogen atom or -SO2-R 3 , R 3 represents a substituted or unsubstituted alkyl group, aralkyl group, or aryl group, R 2 represents a hydrogen atom or an alkyl group, and m represents 0 or 1.)

Description

Technical Field

[0001] The present invention provides a thermal recorder having a thermal recording layer on a support, the support being a water-dispersible paper substrate. The thermal recorder is water-dispersible and has excellent reprintability among various properties required for thermal recorders, as well as excellent resistance to damp heat, plasticizers, and solvents. Background Technology

[0002] Generally, thermal recorders are products obtained by coating a coating solution containing colorless or light-colored electron-donating leuco dyes (hereinafter also called "leuco dyes") and electron-accepting color developers (hereinafter also called "color developers") onto a support such as paper, synthetic paper, film, or plastic. The image is recorded through a transient chemical reaction caused by heating using a thermal printhead, thermal embossing, thermal pen, laser, or similar means. Thermal recorders are widely used as recording media in fax machines, computer terminal printers, automatic ticket vending machines, measuring recorders, and receipts in supermarkets and convenience stores.

[0003] In recent years, thermal recorders have been expanded to various applications such as tickets, receipts, labels, bank ATMs, gas and electricity meter readings, and transportation tickets. Therefore, there is an increasing demand for various properties such as water resistance, plasticizer resistance of the image section, heat resistance of the white paper section, oil resistance, and preservation of the image section and white paper section under harsh conditions.

[0004] To address these requirements, a thermal recorder has been disclosed that improves water resistance, plasticizer resistance of the image section, and heat resistance of the white paper section by using two specific color developers in combination (Patent Document 1). Urea compounds have also been disclosed as color developers used to improve the required performance of thermal recorders, such as color concentration, whiteness, and preservation of the printed section (Patent Documents 2-4, etc.).

[0005] In addition, various types of water-dispersible sheets have been disclosed (Patent Documents 5-7, etc.).

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2015-80852

[0009] Patent Document 2: International Publication WO2019 / 044462

[0010] Patent Document 3: International Publication WO2021 / 095751

[0011] Patent Document 4: International Publication WO2021 / 171983

[0012] Patent Document 5: International Publication WO2018 / 088179

[0013] Patent Document 6: International Publication WO2019 / 049619

[0014] Patent Document 7: International Publication WO2019 / 130968 Summary of the Invention

[0015] The problem that the invention aims to solve

[0016] The inventors aim to develop a thermal recording tag comprising a water-dispersible thermal recorder and an adhesive layer. However, if only the support is given water dispersibility, problems such as poor reprintability will exist (see Reference Example 1 and Comparative Examples 1 and 2 described later). Here, reprintability refers to the effective color sensitivity exhibited when the manufactured thermal recorder is stored under high temperature / high humidity conditions for a certain period of time and then printed.

[0017] Therefore, the object of the present invention is to provide a water-dispersible thermal recorder that has excellent reprintability among the various properties required for thermal recorders, and excellent resistance to damp heat, plasticizers, and solvents.

[0018] Methods for solving problems

[0019] The inventors conducted in-depth research and discovered that by including a specific urea compound as a color developer in the thermal recording layer and using a specific water-dispersible paper substrate in the support, a thermal recorder and thermal recording label with excellent water dispersibility, reprintability, resistance to damp heat, resistance to plasticizers, and resistance to solvents can be provided, thus completing the present invention.

[0020] That is, the present invention is a thermal recorder having a thermal recording layer on a support containing a colorless or light-colored electron-donating leuco dye and an electron-accepting color developer, wherein the thermal recording layer contains at least one urea compound represented by the following general formula (chemical formula 1) as an electron-accepting color developer.

[0021] [Chemical Formula 1]

[0022]

[0023] (In the formula, X represents -O- or -NH-, R 1 Represents a hydrogen atom or -SO2-R 3 R 3 Indicates substituted or unsubstituted alkyl, aralkyl, or aryl groups, R 2 (This represents a hydrogen atom or an alkyl group; m represents 0 or 1.)

[0024] The support contains a paper substrate that is water-dispersible;

[0025] The present invention also provides a thermal recording tag, wherein an adhesive layer is provided on the surface of the thermal recording body opposite to the surface of the support body on which the thermal recording layer is provided. Detailed Implementation

[0026] The thermal recorder of the present invention has a thermal recording layer on a support, the thermal recording layer containing a specific urea compound as an electron-accepting colorimetric agent, and the support is a paper substrate for a specific water-dispersible sheet.

[0027] As the paper substrate of the present invention (hereinafter also referred to as "base paper"), any of the following paper substrates (1) to (3) are used.

[0028] (1) A paper substrate comprising an inner layer and two surface layers disposed on both sides of the inner layer, each surface layer being independently formed of a mixed pulp comprising wood pulp and refined pulp containing 88% by weight or more of α-cellulose, the mixed pulp having a Canadian standard freeness of 450 ml to 600 ml CSF and the wood pulp content in the mixed pulp being 50% to 95% by weight; the inner layer being formed of a second mixed pulp comprising wood pulp and refined pulp containing 88% by weight or more of α-cellulose, the second mixed pulp having a Canadian standard freeness of 600 ml to 750 ml CSF and the wood pulp content in the second mixed pulp being 50% to 95% by weight.

[0029] The inner and surface layers (including the first and second surface layers) of the base paper are both formed from a mixed pulp containing wood pulp and refined pulp (hereinafter also referred to as "refined pulp") with an α-cellulose content of 88% by weight or more.

[0030] The wood pulp used can be wood pulp fibers or non-wood pulp fibers commonly used in papermaking, with an α-cellulose content of less than 88% by weight. Examples of such wood pulp include: softwood sulfate pulp, hardwood sulfate pulp, and other wood pulp fibers; flax pulp, Manila hemp pulp, kenaf pulp, and other non-wood pulp fibers. The average fiber length of the wood pulp is 0.1 mm to 5 mm, preferably 0.5 mm to 3 mm, and more preferably 0.8 mm to 2 mm.

[0031] The refined pulp used here refers to pulps that, like mercerized pulps or dissolving pulps made from wood such as coniferous trees and broad-leaved trees, or non-wood materials such as flax and cotton, have improved cellulose purity by strengthening the digestion conditions during pulp manufacturing, removing hemicellulose through chemical treatment before or after digestion, and refining the α-cellulose content to 88% by weight or more.

[0032] Regarding the relationship between the α-cellulose and hemicellulose content of pulp, Japanese Patent Publication No. 2010-504376 describes the classification of pulp into three groups based on the degree of refining: highly refined pulp is called "acetic acid grade," refined pulp is called "viscose grade," and unrefined pulp is called "paper / fluff grade," and the content of each grade is listed. It is known that "acetic acid grade" pulp typically contains 95% by weight or more α-cellulose and approximately 1% to 3% hemicellulose; "viscose grade" pulp contains 88% to 95% by weight α-cellulose and approximately 5% to 12% hemicellulose; and "paper / fluff grade" pulp contains 80% to 88% by weight α-cellulose and approximately 12% to 20% hemicellulose.

[0033] As can be seen from the above, the refined pulp used in this invention contains less than 12% hemicellulose by weight.

[0034] It should be noted that pulp is usually defined as "an aggregate of cellulose fibers extracted from wood and other plants through mechanical or chemical processing" (Pulp Dictionary, edited by the Pulp Association and published by Kinbara, February 20, 2013).

[0035] Mercerized pulp refers to pulp obtained by impregnating sulfate pulp or sulfite pulp in a strongly alkaline solution and then washing it with water to remove the alkaline components.

[0036] Dissolving pulp is a high-purity cellulose pulp obtained through sulfite hydrolysis and pre-hydrolysis sulfate hydrolysis. By combining bleaching and refining after hydrolysis, pulps of various cellulose purities can be obtained.

[0037] Here, the α-cellulose content is used as an indicator of the cellulose purity of the refined pulp. The α-cellulose content of the refined pulp needs to be 88% by weight or more, preferably 92% by weight or more, and more preferably 95% by weight or more. When the α-cellulose content of the refined pulp is less than 88% by weight, it is difficult to disperse into single fibers, thus reducing its dispersibility in water. It should be noted that in this invention, the α-cellulose content is a value determined by measuring α-cellulose as specified in TAPPI standard T203om-83 (JIS P8101-1994 (now discontinued)).

[0038] Alternatively, hemicellulose content can be used as another indicator of the cellulose purity of refined pulp. In this case, the hemicellulose content of the refined pulp needs to be less than 12% by weight, preferably less than 8% by weight, and more preferably less than 5% by weight. When the hemicellulose content of the refined pulp is 12% by weight or more, its dispersibility in water decreases because it is difficult to disperse into single fibers. It should be noted that in this invention, the hemicellulose content can be determined by the following method: acid hydrolysis of refined or unrefined pulp to obtain monosaccharides, and the composition of the monosaccharides is quantified according to the sugar alcohol acetate esterification method. That is, the monosaccharides obtained by pulp hydrolysis are reduced to an equivalent amount of sugar alcohol acetate using sodium borohydride, and acetylated by glacial acetic acid and pyridine to prepare sugar alcohol acetate derivatives. Then, the sugar alcohol acetate derivatives are analyzed by gas chromatography to determine and quantify the constituent sugars.

[0039] It should be noted that for paper made from a blend of refined and unrefined pulp, the α-cellulose and hemicellulose contents can be determined in the same manner as when each pulp is used individually. Furthermore, by observing the fiber morphology of the pulp and determining the blending ratio of refined and unrefined pulp, the α-cellulose and hemicellulose contents can be calculated separately for each type of pulp.

[0040] The blended pulp used here does not contain regenerated cellulose fibers such as rayon, fibrous carboxyalkyl cellulose, or fibrous carboxyalkyl cellulose salts (e.g., CMC-Na salts).

[0041] Due to insufficient sheet strength and smoothness, the printability of regenerated cellulose fibers becomes poor. Fibrous carboxyalkyl cellulose is acidic, and depending on the application, acidity can have adverse effects. Depending on the application, alkaline compounds remaining in the base paper from fibrous carboxyalkyl cellulose salts can also have adverse effects and easily cause discoloration.

[0042] It should be noted that this problem will not occur when the paper is made as described later, and then a neutral water-soluble polymer solution is applied to the water-dispersible sheet using methods such as sizing and pressing coating.

[0043] The inner layer constituting the base paper is formed of a mixed pulp comprising wood pulp and refined pulp with an α-cellulose content of 88% by weight or more, wherein the wood pulp content in the mixed pulp is 50-95% by weight, preferably 40-70% by weight.

[0044] The Canadian standard freeness of the mixed pulp used in this inner layer is 600–750 ml CSF, preferably 630–720 ml CSF. This Canadian standard freeness is determined according to JIS P8121-22012 (the same applies hereinafter).

[0045] As pulping progresses (freeness decreases), the fiber fine fiberization, breakage, and internal swelling increase, resulting in improved density, strength, and smoothness of the base paper, but reduced water dispersibility.

[0046] The surface layer constituting the base paper (including the first surface layer and the second surface layer) is formed from a mixed pulp containing wood pulp and refined pulp with an α-cellulose content of 88% by weight or more. The mixed pulp in the surface layer (first surface layer) on which the adhesive layer is disposed has a Canadian standard freeness of 450 to 600 ml CSF, preferably 500 to 575 ml CSF, and the wood pulp content in the mixed pulp is 50 to 95% by weight, preferably 65 to 80% by weight.

[0047] The pH of the paper surface layer constructed in this way is 6-8 (neutral region).

[0048] On the other hand, the Canadian standard freeness of the mixed pulp and the wood pulp content in any surface layer (second surface layer) on which no adhesive layer is disposed can be appropriately set according to the intended use. These compositions of the second surface layer may be the same as those of the first surface layer or the same as those of the inner layers.

[0049] It should be noted that, in order to set the Canadian standard freeness of the blended pulp used in the inner and surface layers to the range described above, the Canadian standard freeness of the wood pulp and refined pulp can be the same or different. Furthermore, the blended pulp can be made by separately beating the wood pulp and refined pulp before mixing, or by mixing them before beating.

[0050] A water-soluble polymer is coated or impregnated on the surface of the aforementioned paper substrate, thereby imparting water dispersibility (especially for fibrous dispersion).

[0051] When impregnating or coating the water-soluble polymer, use a neutral (pH 6–8) solution (e.g., a neutral aqueous solution).

[0052] There are no particular limitations on the method of impregnation or coating. Methods such as sizing press coating (usually two-roll sizing press coating), paper transfer roller coating, spray coating, gravure coating, and curtain coating can be used. From the point of view of productivity, sizing press coating is preferred.

[0053] By impregnating or coating the surface layer of the water-dispersible sheet constructed according to the present invention with water-soluble polymer, the water-soluble polymer can fill the gaps between the fibers of the base paper. While improving the drying strength of the water-dispersible sheet, the water-soluble polymer present in the gaps between the fibers expands between the fibers by swelling upon contact with water, thus allowing the fibers to be easily separated.

[0054] Preferred water-soluble polymers are those that readily redissolve in water after drying and coating. Examples include: anionic polymeric electrolyte salts such as carboxyalkyl cellulose salts, alginates, pectinates, polyacrylates, polymethyl methacrylates, carboxyalkylated starch, phosphorylated starch, and anionic polyacrylamide; non-electrolytes such as methylcellulose, hydroxyalkylcellulose, polyvinyl alcohol, polyvinylpyrrolidone, polyepoxyalkylene, polyvinyl ethyl ether, hydroxyethylated starch, oxidized starch, and α-starch; water-soluble polysaccharides such as guar gum, tragacanth gum, xanthan gum, gum arabic, carrageenan, galactomannan, amylopectin, dextran, and dextrin; and water-soluble proteins such as gelatin and casein. These water-soluble polymers can be used alone or in combination of two or more. Among these, carboxymethyl cellulose salts are preferred for improving water dispersibility and strength.

[0055] (2) A paper substrate comprising an inner layer and two surface layers disposed on both sides of the inner layer, the inner layer comprising papermaking fibers with a Canadian standard freeness of 600-750 ml CSF and alkalized fibrous carboxymethyl cellulose, the surface layers each independently comprising papermaking fibers and alkalized fibrous carboxymethyl cellulose, wherein the papermaking fibers in at least one surface layer have a Canadian standard freeness of 400-575 ml CSF and the content of the papermaking fibers is 60-90% by mass.

[0056] The water-dispersible sheet of the present invention comprises a paper substrate (hereinafter also referred to as "base paper") and an adhesive layer, the base paper comprising an inner layer and at least one surface layer. The water-dispersible label has an adhesive layer on one surface layer of the base paper (hereinafter also referred to as "first surface layer"). The water-dispersible label may also have a second surface layer on the side of the inner layer opposite to the first surface layer. The structure of the water-dispersible sheet of the present invention is shown in FIG1.

[0057] The inner layer and surface layer (including the first surface layer and the second surface layer) of the base paper constituting the present invention both contain papermaking fibers and fibrous carboxymethyl cellulose.

[0058] Examples of papermaking fibers include wood pulp fibers or non-wood pulp fibers commonly used in papermaking, such as: softwood sulfate pulp, hardwood sulfate pulp, dissolving pulp, mercerized pulp, and other wood pulp fibers; flax pulp, Manila hemp pulp, kenaf pulp, and other non-wood pulp fibers; and refined cellulose fibers such as lyocell. The average fiber length of the water-dispersible fiber used in papermaking is 0.1–5 mm, preferably 0.5–3 mm, and more preferably 0.8–2 mm.

[0059] This fibrous carboxymethyl cellulose is obtained by carboxylating natural cellulose fibers, regenerated cellulose fibers, or refined cellulose fibers using known methods, and is insoluble in water. Specific examples include fibrous carboxymethyl cellulose and fibrous carboxyethyl cellulose. The degree of substitution of the carboxyl group in the fibrous carboxymethyl cellulose is preferably 0.2 to 1.0, more preferably 0.4 to 0.6.

[0060] In this invention, an alkalizing agent is used to alkalize fibrous carboxymethyl cellulose. By alkalizing the base paper, the water-insoluble fibrous carboxymethyl cellulose in the base paper is converted into water-soluble fibrous carboxymethyl cellulose salts through a neutralization reaction. As a result, the base paper becomes easily dispersed in water due to fiber swelling, exhibiting water dispersibility.

[0061] The alkalizing agent is an aqueous solution of an alkaline compound. Specific examples include aqueous solutions of the following compounds: hydroxides of alkali metals such as sodium hydroxide and potassium hydroxide; carbonates and bicarbonates of alkali metals such as sodium carbonate and sodium bicarbonate; phosphates and hydrogen phosphates of alkali metals such as sodium hydrogen phosphate; organic acid salts of alkali metals such as sodium acetate; hydroxides of alkaline earth metals such as calcium hydroxide; ammonia and ammonium salts; amines such as ethanolamine; and polyethylene imines with a molecular weight of less than 1000.

[0062] The alkalization can be carried out by mixing the alkalizing agent into the pulp during the papermaking process of the base paper, or by transferring the alkalizing agent to the pulp after papermaking by spraying it with a sprayer, coating it with a coating machine, or adhering it to the papermaking felt, etc., and can be carried out by appropriate methods.

[0063] It should be noted that this alkalization can be performed by containing an alkalizing agent in the first or second surface layer before the adhesive layer is applied to the base paper, or by containing an alkalizing agent in the second surface layer after the adhesive layer is applied to the base paper. Alternatively, if alkalization is performed during the papermaking process of the base paper as described above, the adhesive layer can simply be applied to the first surface layer of the base paper.

[0064] Alternatively, when the coating layer described later is applied to the second surface layer, the second surface layer may contain an alkalizing agent before the coating layer is applied. If the adhesive layer is applied to the base paper, the first surface layer may contain an alkalizing agent after the coating layer is applied. Furthermore, if the base paper is alkalized during papermaking as described above, the coating layer can be applied to the second surface layer.

[0065] When applying an alkalizing agent to base paper using a coating machine, the alkalizing agent can be an aqueous solution of the aforementioned alkaline compound, or a mixture of an aqueous organic solvent compatible with the aqueous solution, and can be applied using a known coating machine such as an air knife coating machine, a rod coating machine, a roller coating machine, a doctor blade coating machine, a curtain coating machine, a Champrex coating machine, or a gravure coating machine.

[0066] Furthermore, in order to adjust the viscosity to a suitable level for the coating machine used and to prevent the alkaline compound from detaching after drying, a water-soluble polymer compatible with the aqueous solution of the aforementioned alkaline compound can also be incorporated into the solution. Examples of such water-soluble polymers include starch and starch derivatives, cellulose derivatives such as carboxyalkyl cellulose salts, alginate, and polyacrylate.

[0067] The coating amount of these alkaline compounds is preferably at least the neutralization equivalent of the fibrous carboxymethyl cellulose in the base paper, more preferably 1 to 3 times the neutralization equivalent. When the amount of alkaline compounds is less than the neutralization equivalent, the water-insoluble fibrous carboxymethyl cellulose remains, making it difficult to achieve sufficient water dispersibility. As a result, the carboxymethyl cellulose binds together over time, significantly reducing solubility. Furthermore, when the amount of alkaline compounds exceeds 3 times the neutralization equivalent, the residual alkaline compounds in the base paper can cause changes in appearance and material properties, such as discoloration and reduced strength, which is not preferred.

[0068] The content of basic compounds in the base paper varies depending on the unit area weight of the base paper, the degree of substitution and blending ratio of fibrous carboxyalkyl cellulose, and the type of basic compound used, therefore appropriate adjustments are necessary. For example, when the basic compound is sodium carbonate, the content of the basic compound relative to the weight of the base paper is 0.3–67% by weight; when the basic compound is sodium hydroxide, the content of the basic compound relative to the weight of the base paper is 0.2–51% by weight.

[0069] For water-dispersible sheets (especially their base paper), water-soluble polymers can be coated or impregnated to improve their water dispersibility and drying strength. For example, when alkalizing the base paper, water-soluble polymers can be added to an aqueous solution of the alkaline compound. This allows the water-soluble polymers to fill the interfiber gaps in the base paper, improving the drying strength of the water-dispersible sheet. Simultaneously, the water-soluble polymers present in the interfiber gaps swell upon contact with water and expand between the fibers, thus facilitating fiber separation.

[0070] As for this water-soluble polymer, substances that are easily redissolved in water when dried and coated are preferred. Examples include starch and starch derivatives, carboxyl cellulose salts, hydroxyalkyl cellulose, alkyl cellulose and other cellulose derivatives, alginate, xanthan gum and other natural polymers; polyacrylates, polyvinyl alcohol, carboxyl-modified polyvinyl alcohol and other modified polyvinyl alcohols, polyvinylpyrrolidone, gelatin, casein, etc. These can be used alone or in combination of two or more. Among them, carboxymethyl cellulose salt is preferred from the perspective of improving water dispersibility and strength.

[0071] The inner layer of the base paper constituting the present invention comprises papermaking fibers and alkalized fibrous carboxymethyl cellulose strands. The content of papermaking fibers in the inner layer is preferably 20 to 80% by weight, more preferably 40 to 70% by weight.

[0072] The Canadian standard freeness of the papermaking fibers used in this inner layer is 600–750 ml CSF, preferably 630–720 ml CSF. This Canadian standard freeness is determined according to JIS P8121-22012 (the same applies hereinafter).

[0073] As pulping progresses (freeness decreases), the fiber fine fiberization, breakage, and internal swelling increase, resulting in improved density, strength, and smoothness of the base paper, but reduced water dispersibility.

[0074] The surface layer constituting the base paper (including the first surface layer and the second surface layer) contains papermaking fibers and alkalized fibrous carboxymethyl cellulose.

[0075] In addition, the Canadian standard freeness of the papermaking fibers in the surface layer (first surface layer) on which the adhesive layer is disposed is 400-575 ml CSF, preferably 425-525 ml CSF, and the content of the papermaking fibers is 60-90% by mass, preferably 65-80% by weight.

[0076] On the other hand, the Canadian standard freeness and content of papermaking fibers in any surface layer (second surface layer) on which no adhesive layer is disposed can be appropriately set according to the intended use. These components of the second surface layer can be the same as those of the first surface layer or the same as those of the inner layers.

[0077] (3) A paper substrate comprising papermaking fibers and alkalized fibrous carboxyalkyl cellulose, and further comprising a carboxyalkyl cellulose salt having a degree of etherification of 0.2 to 0.6, a degree of etherification of 0.5 to 1.6, a viscosity of 2 to 200 mPa·s measured using a Brookfield viscometer for a 1% by weight aqueous solution of the carboxyalkyl cellulose salt, and a proportion of the carboxyalkyl cellulose salt of 0.1 to 10% by weight relative to the total of the papermaking fibers and the alkalized fibrous carboxyalkyl cellulose.

[0078] The paper substrate comprises papermaking fibers, alkalized fibrous carboxyalkyl cellulose, and carboxyalkyl cellulose salts.

[0079] Examples of fibers used for papermaking include wood pulp fibers or non-wood pulp fibers commonly used in papermaking, such as softwood sulfate pulp, hardwood sulfate pulp, dissolving pulp, mercerized pulp, and other wood pulp fibers; flax pulp, Manila hemp pulp, kenaf pulp, and other non-wood pulp fibers; and refined cellulose fibers such as lyocell. The average fiber length of the water-dispersible fiber used in papermaking is 0.1–5 mm, preferably 0.5–3 mm, and more preferably 0.8–2 mm.

[0080] The Canadian standard freeness of the papermaking fiber is preferably 200–750 ml CSF, more preferably 350–720 ml CSF, and even more preferably 500–700 ml CSF. This Canadian standard freeness is determined according to JIS P8121-2:2012 (the same applies hereinafter).

[0081] As pulping progresses (freeness decreases), the fiber fine fiberization, breakage, and internal swelling increase, resulting in improved density, strength, and smoothness of the base paper, but reduced water dispersibility.

[0082] The content of papermaking fibers in the base paper of the present invention is preferably 20-95% by weight, more preferably 30-90% by weight, and even more preferably 40-80% by weight.

[0083] The fibrous carboxyalkyl cellulose used here is obtained by carboxylating natural cellulose fibers, regenerated cellulose fibers, or refined cellulose fibers using known methods, and is insoluble in water. Specific examples include fibrous carboxymethyl cellulose and fibrous carboxyethyl cellulose.

[0084] The degree of etherification (hereinafter also referred to as "DS") of the fibrous carboxyalkyl cellulose is 0.2 to 0.6, preferably 0.4 to less than 0.6 (i.e., 0.4 or more and less than 0.6). This degree of etherification refers to the degree of substitution of the carboxyl groups in the fibrous carboxyalkyl cellulose. When the degree of etherification is low, for example below 0.2, water solubility is improved; conversely, when the degree of etherification is high, for example above 0.6, adhesion to the papermaking wire occurs during the papermaking process of the base paper, making production difficult. Therefore, in this application, fibrous carboxyalkyl cellulose with the degree of etherification described above is used.

[0085] The fibrous carboxyalkyl cellulose is alkalized using an alkalizing agent. The alkalization is as described above.

[0086] To improve the water dispersibility of the thermal recorder (especially the thermal recorder with an adhesive layer), the carboxyalkyl cellulose salt used here preferably has a specific viscosity range. That is, the viscosity of a 1% by weight aqueous solution of the carboxyalkyl cellulose salt, measured using a Brookfield viscometer, is 2 to 200 mPa·s, preferably 2 to 100 mPa·s. When this viscosity is too high, a film will form on the surface of the water-dispersible sheet, water penetration will be poor, and thus water dispersibility will deteriorate.

[0087] The carboxyalkyl cellulose salt refers to a salt formed by converting the carboxyl group of carboxyalkyl cellulose through alkali metals such as sodium and potassium.

[0088] Among these, carboxyalkyl cellulose salts are preferred for use in this invention, considering their ability to improve water dispersibility and strength.

[0089] The degree of etherification (DS) of the carboxyalkyl cellulose salt is 0.5 to 1.6, preferably 0.6 to 1.0 (i.e., 0.6 or more and 1.0 or less). The higher the degree of etherification of the carboxyalkyl cellulose salt, for example, when the degree of etherification is around 0.5 to 1.6, the better the water solubility.

[0090] The degree of etherification of fibrous carboxyalkyl cellulose is preferably lower than that of the carboxyalkyl cellulose salt.

[0091] The proportion of the carboxyalkyl cellulose salt is 0.1 to 10% by weight, preferably 0.5 to 7% by weight, relative to the total amount of papermaking fibers and alkalized fibrous carboxyalkyl cellulose. When the proportion of the carboxyalkyl cellulose salt is too high, a film will form on the surface of the water-dispersible sheet, water penetration will be poor, and thus water dispersibility will deteriorate.

[0092] The addition of the carboxyalkyl cellulose salt can be carried out by mixing the carboxyalkyl cellulose salt into the pulp during the papermaking process of the base paper, or by coating the carboxyalkyl cellulose salt with a coating machine after papermaking, or by attaching it to papermaking felt, etc., thereby transferring it to the pulp. It can be carried out by appropriate methods.

[0093] The base paper of this invention typically has a unit area weight of 10–200 g / m². 2 In particular, the base paper for coated paper used in printing is typically suitable at 50 g / m². 2 The above values ​​are preferably between 50 and 120 g / m³. 2 The range.

[0094] In addition, the weight per unit area of ​​each layer is typically 5–100 g / m². 2 Preferably, it is 10–100 g / m 2 The range.

[0095] Hereinafter, various materials used in the thermal recording layer of the thermal recorder of the present invention are exemplified, but binders, crosslinking agents, pigments, etc., may also be used in each coating layer provided as needed, without hindering the desired effect for the above-mentioned problems.

[0096] For the thermal recorder of the present invention, its thermal recording layer contains at least one urea compound represented by the following general formula (chemical formula 1) as a colorimetric agent.

[0097] [Chemical Formula 1]

[0098]

[0099] (In the formula, X represents -O- or -NH-, R 1 Represents a hydrogen atom or -SO2-R 3 R 3 Indicates substituted or unsubstituted alkyl, aralkyl, or aryl groups, R 2 (This represents a hydrogen atom or an alkyl group; m represents 0 or 1.)

[0100] The preferred urea compound is (1) or (2) described below.

[0101] (1) The first urea compound represented by the following general formula (chemical formula 2).

[0102] [Chemical Formula 2]

[0103]

[0104] (where R is in the formula) 1 R 2 and R 3 Same as the definition described above.

[0105] (2) The second urea compound represented by the following formula (chemical formula 3).

[0106] [Chemical Formula 3]

[0107]

[0108] (where R is in the formula) 2 As defined above, R 4 ~R 8 The definition will be given later.

[0109] The first urea compound used in this invention is preferably represented by the following formula (Chemical Formula 4).

[0110] [Chemical Formula 4]

[0111]

[0112] In general formulas (chemical formula 2) and (chemical formula 4), R 3 It can be a substituted or unsubstituted alkyl, aralkyl, or aryl group, preferably a substituted or unsubstituted aryl group.

[0113] In these cases of substitution, the substituents are preferably alkyl groups having 1 to 12 carbon atoms, alkoxy groups having 1 to 12 carbon atoms, aryl groups having 6 to 12 carbon atoms, or halogen atoms. Additionally, multiple R... 3 They can be the same or different.

[0114] R in the benzene ring of general formula (chemical formula 2) 1 The positions of -O- can be the same or different, preferably 3, 4 or 5.

[0115] R in the benzene ring of general formula (chemical formula 2) and general formula (chemical formula 4) 3 The positions of -SO2-O- can be the same or different, preferably 3, 4 or 5.

[0116] The alkyl group is, for example, a straight-chain, branched, or alicyclic alkyl group, and preferably has 1 to 12 carbon atoms. Examples of such alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, cyclopentyl, hexyl, cyclohexyl, 2-ethylhexyl, lauryl, etc.

[0117] The aralkyl group preferably has 7 to 12 carbon atoms. Examples of such aralkyl groups include: benzyl, 1-phenylethyl, 2-phenylethyl, 3-phenylpropyl, p-methylbenzyl, m-methylbenzyl, m-ethylbenzyl, p-ethylbenzyl, p-isopropylbenzyl, p-tert-butylbenzyl, p-methoxybenzyl, m-methoxybenzyl, o-methoxybenzyl, m-, p-dimethoxybenzyl, p-ethoxym-methoxybenzyl, p-phenylmethylbenzyl, p-cumylbenzyl, p-phenylbenzyl, o-phenylbenzyl, m-phenylbenzyl, p-tolylbenzyl, m-tolylbenzyl, o-tolylbenzyl, p-chlorobenzyl, and other unsubstituted or substituted aralkyl groups, alkoxy groups, aralkyl groups, aryl groups, or halogen groups.

[0118] The aryl group preferably has 6 to 12 carbon atoms. Examples of such aryl groups include: phenyl, p-tolyl, m-tolyl, o-tolyl, 2,5-dimethylphenyl, 2,4-dimethylphenyl, 3,5-dimethylphenyl, 2,3-dimethylphenyl, 3,4-dimethylphenyl, mesitylene, p-ethylphenyl, p-isopropylphenyl, p-tert-butylphenyl, p-methoxyphenyl, 3,4-dimethoxyphenyl, p-ethoxyphenyl, p-chlorophenyl, 1-naphthyl, 2-naphthyl, tert-butylated naphthyl, and other unsubstituted or substituted aryl groups with alkyl, alkoxy, aralkyl, aryl, or halogen atoms.

[0119] In the above general formulas (chemical formulas 1, 2, and 4), R 3 Preferably, the group is represented by the following formula.

[0120] [Chemical Formula 5]

[0121]

[0122] (where R is in the formula) 4 ~R 8 These can be the same or different, representing hydrogen atoms, halogen atoms, nitro groups, amino groups, alkyl groups, alkoxy groups, aryloxy groups, alkyl carbonyloxy groups, aryl carbonyloxy groups, alkyl carbonyl amino groups, aryl carbonyl amino groups, alkyl sulfonyl amino groups, aryl sulfonyl amino groups, monoalkyl amino groups, dialkyl amino groups, or aryl amino groups.

[0123] R 2 The symbol represents a hydrogen atom or an alkyl group, preferably a hydrogen atom. The alkyl group is preferably an alkyl group having 1 to 4 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, etc.

[0124] R in the benzene ring of general formula (chemical formula 2) 2 The positions can be the same or different, preferably 3, 4 or 5.

[0125] As the first urea compound of the present invention, a urea compound represented by the following general formula (Chemical Formula 6) is further preferred.

[0126] [Chemical Formula 6]

[0127]

[0128] In the general formula (Chemical Formula 6), R 9 It is an alkyl or alkoxy group, preferably an alkyl group, where o represents an integer from 0 to 3, preferably 0 to 2, more preferably 0 to 1. The alkyl group has, for example, 1 to 12 carbon atoms, preferably 1 to 8, more preferably 1 to 4.

[0129] R in the benzene ring of general formula (chemical formula 6) 9The positions can be the same or different, preferably 3, 4 or 5, preferably 4.

[0130] In addition, examples of the first urea compound of the present invention include: N,N'-di-[3-(benzenesulfonyloxy)phenyl]urea, N,N'-di-[3-(benzenesulfonyloxy)-4-methyl-phenyl]urea, N,N'-di-[3-(benzenesulfonyloxy)-4-ethyl-phenyl]urea, N,N'-di-[3-(benzenesulfonyloxy)-5-methyl-phenyl]urea, N,N'-di-[3-(benzenesulfonyloxy)-4-propyl-phenyl]urea, N,N'-di-[3-(o-toluenesulfonyloxy)phenyl]urea, N,N'-di-[3-(m-toluenesulfonyloxy)phenyl]urea, and N,N'-di-[3-(p-toluenesulfonyloxy)phenyl]urea. [Phenylacetyl]urea, N,N'-di-[3-(p-toluenesulfonyloxy)-4-methyl-phenyl]urea, N,N'-di-[3-(p-toluenesulfonyloxy)phenyl]urea, N,N'-di-[3-(m-toluenesulfonyloxy)phenyl]urea, N,N'-di-[3-(tris(toluenesulfonyloxy)phenyl]urea, N,N'-di-[3-(1-naphthalenesulfonyloxy)phenyl]urea, N,N'-di-[3-(2-naphthalenesulfonyloxy)phenyl]urea, N,N'-di-[3-(p-ethylbenzenesulfonyloxy)phenyl]urea, N,N'-di-[3-(p-propylbenzenesulfonyloxy)phenyl]urea, N,N'-di-[3-(p-isopropylbenzenesulfonyloxy)phenyl]urea N,N'-di-[3-(p-tert-butylbenzenesulfonyloxy)phenyl]urea, N,N'-di-[3-(p-methoxybenzenesulfonyloxy)phenyl]urea, N,N'-di-[3-(m-methoxybenzenesulfonyloxy)phenyl]urea, N,N'-di-[3-(o-methoxybenzenesulfonyloxy)phenyl]urea, N,N'-di-[3-(m-,p-dimethoxybenzenesulfonyloxy)phenyl]urea, N,N'-di-[3-(p-ethoxybenzenesulfonyloxy)phenyl]urea, N,N'-di-[3-(p-propoxybenzenesulfonyloxy)phenyl]urea, N,N'-di-[3-(p-butoxybenzenesulfonyloxy)phenyl]urea, N,N'-di-[3-(p-cumylbenzylsulfonyloxy)phenyl]urea, N,N'-di-[3-(p-cumylbenzylsulfonyloxy)phenyl]urea, N,N'-di-[3-(o-phenylbenzylsulfonyloxy)phenyl]urea, N,N'-di-[3-(p-phenylbenzylsulfonyloxy)phenyl]urea, N,N'-di-[3-(p-chlorobenzylsulfonyloxy)phenyl]urea, N,N'-di-[4-(benzylsulfonyloxy)phenyl]urea, N,N'-di-[4-(p-toluenesulfonyloxy)phenyl]urea, N,N'-di-[3-(ethanesulfonyloxy)phenyl]urea, N,N'-di-[3-(benzylsulfonyloxy)phenyl]urea, etc., but not limited to these.

[0131] As the second urea compound used in this invention, N-[2-(3-phenylureo)phenyl]benzenesulfonamide is preferred. This compound is represented by the following formula and can be obtained, for example, as the trade name NKK1304 from Nippon Soda Corporation.

[0132] [Chemical Formula 7]

[0133]

[0134] The content of urea compounds in the thermal recording layer of the present invention (solid component, total amount when including multiple urea compounds) is 1.0 to 70.0% by weight, preferably 5.0 to 65.0% by weight, more preferably 10.0 to 60.0% by weight.

[0135] The content of the first urea compound in the thermal recording layer of the present invention is 1.0 to 50.0% by weight, preferably 5.0 to 40.0% by weight. Furthermore, the content of the second urea compound is 5.0 to 50.0% by weight, preferably 5.0 to 40.0% by weight.

[0136] It should be noted that when the thermal recording layer of the present invention contains a first urea compound and a second urea compound, the content of the second urea compound in the thermal recording layer is preferably 0.1 to 30.0 parts by weight, more preferably 0.5 to 25.0 parts by weight, further preferably 1.0 to 20.0 parts by weight, and particularly preferably 2.0 to 15.0 parts by weight, relative to 1.0 parts by weight of the first urea compound.

[0137] The thermal recording layer of the present invention can also use colorimetric agents other than the first or second urea compounds mentioned above. Examples of such colorimetric agents include: activated clay, palygorskite, colloidal silica, aluminum silicate and other inorganic acidic substances, 4,4'-isopropylidene diphenol, 1,1-bis(4-hydroxyphenyl)cyclohexane, 2,2-bis(4-hydroxyphenyl)-4-methylpentane, 4,4'-dihydroxydiphenyl sulfide, hydroquinone monobenzyl ether, benzyl 4-hydroxybenzoate, 4,4'-dihydroxydiphenyl sulfone, 2,4'-dihydroxydiphenyl sulfone, 4-hydroxy-4'-isopropylidene diphenyl sulfone, etc. Propoxy diphenyl sulfone, 4-hydroxy-4'-n-propoxy diphenyl sulfone, bis(3-allyl-4-hydroxyphenyl) sulfone, 4-hydroxy-4'-methyl diphenyl sulfone, 4-hydroxyphenyl-4'-benzyloxyphenyl sulfone, 3,4-dihydroxyphenyl-4'-methylphenyl sulfone, 1-[4-(4-hydroxybenzenesulfonyl)phenoxy]-4-[4-(4-isopropoxybenzenesulfonyl)phenoxy]butane, the phenol condensation composition disclosed in Japanese Patent Application Publication No. 2003-154760, the aminobenzenesulfonamide derivative disclosed in Japanese Patent Application Publication No. 8-59603, bis(4-hydroxyphenylthioethoxy)methyl Alkane, 1,5-di(4-hydroxyphenylthio)-3-oxapentane, bis(p-hydroxyphenyl)acetic acid butyl ester, bis(p-hydroxyphenyl)acetic acid methyl ester, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, 1,4-bis[α-methyl-α-(4'-hydroxyphenyl)ethyl]benzene, 1,3-bis[α-methyl-α-(4'-hydroxyphenyl)ethyl]benzene, di(4-hydroxy-3-methylphenyl)sulfide, 2,2'-thiobis(3-tert-octylphenol), 2,2'-thiobis(4-tert-octylphenol), as reported in WO02 / 081229 or Japanese Patent Application Publication No. 2002-301873. The reagents include thiourea compounds such as N,N'-di-m-chlorophenylthiourea, p-chlorobenzoic acid, octadecyl gallate, bis[4-(n-octyloxycarbonylamino)zinc salicylate] dihydrate, 4-[2-(p-methoxyphenoxy)ethyloxy]salicylic acid, 4-[3-(p-toluenesulfonyl)propyloxy]salicylic acid, 5-[p-(2-p-methoxyphenoxyethoxy)cumyl]salicylic acid, salts of these aromatic carboxylic acids with polyvalent metals such as zinc, magnesium, aluminum, calcium, titanium, manganese, tin, and nickel, as well as antipyrine complexes of zinc thiocyanate, and zinc salts of p-formylbenzoic acid and other aromatic carboxylic acids. These colorimetric reagents can be used alone or in mixtures of two or more.1-[4-(4-hydroxybenzenesulfonyl)phenoxy]-4-[4-(4-isopropoxybenzenesulfonyl)phenoxy]butane, for example, can be obtained as trade name JKY-214 manufactured by API Corporation. The phenol condensation composition described in Japanese Patent Application Publication No. 2003-154760, for example, can be obtained as trade name JKY-224 manufactured by API Corporation. Additionally, compounds described in WO02 / 081229, etc., can be obtained as trade names NKK-395 and D-100 manufactured by Nippon Soda Co., Ltd. Furthermore, it may also contain metal chelate type coloring components such as higher fatty acid metal complex salts and polyhydroxy aromatic compounds described in Japanese Patent Application Publication No. 10-258577.

[0138] When the thermal recording layer of the present invention contains a color developer other than the first or second urea compound, the total content (solid component) of the first and / or second urea compound used is preferably 50% by weight or more, more preferably 80% by weight or more, and even more preferably 90% by weight or more, relative to all the color developers (including the aforementioned first and / or second urea compounds) contained in the thermal recording layer.

[0139] As the leuco dye used in this invention, any leuco dye known in the field of pressure-sensitive or thermal recording paper can be used without particular limitation, but triphenylmethane compounds, fluoran compounds, fluorene compounds, and divinyl compounds are preferred. Specific examples of representative colorless or light-colored dyes (dye precursors) are shown below. Furthermore, these dye precursors can be used alone or in mixtures of two or more.

[0140] <Triphenylmethane-based leuco dyes>

[0141] 3,3-Bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (also known as crystal violet lactone) and 3,3-bis(p-dimethylaminophenyl)phthalide (also known as malachite green lactone).

[0142] <Fluorane leuco dyes>

[0143] 3-Diethylamino-6-methylfluorane, 3-Diethylamino-6-methyl-7-aniline fluorane, 3-Diethylamino-6-methyl-7-(o,p-dimethylaniline)fluorane, 3-Diethylamino-6-methyl-7-chlorofluorane, 3-Diethylamino-6-methyl-7-(m-trifluoromethylaniline)fluorane, 3-Diethylamino-6-methyl-7-(o-chloroaniline)fluorane, 3-Diethylamino-6-methyl-7-(p-chloroaniline)fluorane, 3-Diethylamino-6-methyl-7-(o-fluoroaniline)fluorane, 3-Diethylamino-6-methyl-7-(m-methylaniline)fluorane, 3-Diethylamino-6-methyl-7-n-octylaniline fluorane, 3-Diethylamino -6-Methyl-7-n-octylaminofluorane, 3-diethylamino-6-methyl-7-benzylaminofluorane, 3-diethylamino-6-methyl-7-dibenzylaminofluorane, 3-diethylamino-6-chloro-7-methylfluorane, 3-diethylamino-6-chloro-7-aniline fluorane, 3-diethylamino-6-chloro-7-p-methylaniline fluorane, 3-diethylamino-6-ethoxyethyl-7-aniline fluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7-(m-trifluoromethylaniline)fluorane, 3-diethylamino-7-(o-chloroaniline)fluorane, 3-diethylamino-7-(p-chloroaniline)fluorane, 3-diethylamino-7-(p-chloroaniline)fluorane, 3-diethylamino-7-(o-chloroaniline)fluorane, 3-Diethylamino-benzo[a]fluorane, 3-Diethylamino-benzo[c]fluorane, 3-Dibutylamino-6-methylfluorane, 3-Dibutylamino-6-methyl-7-aniline fluorane, 3-Dibutylamino-6-methyl-7-(o,p-dimethylaniline)fluorane, 3-Dibutylamino-6-methyl-7-(o-chloroaniline)fluorane, 3-Dibutylamino-6-methyl-7-(p-chloroaniline)fluorane, 3-Dibutylamino-6-methyl-7-(o-fluoroaniline)fluorane, 3-Dibutylamino-6-methyl-7-(m-trifluoromethylaniline)fluorane, 3-Dibutylamino-6-methyl-7-chlorofluorane, 3-Dibutylamino-6-methyl-7-chlorofluorane, 3-Dibutylamino-6- Ethoxyethyl-7-aniline fluorane, 3-dibutylamino-6-chloro-7-aniline fluorane, 3-dibutylamino-6-methyl-7-p-methylaniline fluorane, 3-dibutylamino-7-(o-chloroaniline) fluorane, 3-dibutylamino-7-(o-fluoroaniline) fluorane, 3-di-n-pentylamino-6-methyl-7-aniline fluorane, 3-di-n-pentylamino-6-methyl-7-(p-chloroaniline) fluorane, 3-di-n-pentylamino-7-(m-trifluoromethylaniline) fluorane, 3-di-n-pentylamino-6-chloro-7-aniline fluorane, 3-di-n-pentylamino-7-(p-chloroaniline) fluorane, 3-pyrrolidino-6-methyl-7-aniline fluorane,3-Piperidino-6-methyl-7-anilinofluorane, 3-(N-methyl-N-propylamino)-6-methyl-7-anilinofluorane, 3-(N-methyl-N-cyclohexylamino)-6-methyl-7-anilinofluorane, 3-(N-ethyl-N-cyclohexylamino)-6-methyl-7-anilinofluorane, 3-(N-ethyl-N-xylmethylamino)-6-methyl-7-(p-chloroanilino)fluorane, 3-(N-ethyl-p-toluidine)-6-methyl-7-anilinofluorane, 3-(N-ethyl-N-isopentylamino)-6-methyl-7 -Anilinefluorane, 3-(N-ethyl-N-isopentylamino)-6-chloro-7-anilinefluorane, 3-(N-ethyl-N-tetrahydrofurfurylamino)-6-methyl-7-anilinefluorane, 3-(N-ethyl-N-isobutylamino)-6-methyl-7-anilinefluorane, 3-(N-ethyl-N-ethoxypropylamino)-6-methyl-7-anilinefluorane, 3-cyclohexylamino-6-chlorofluorane, 2-(4-oxahexyl)-3-dimethylamino-6-methyl-7-anilinefluorane, 2-(4-oxahexyl)-3-diethylamino-6-methyl-7-anilinefluorane 2-(4-oxahexyl)-3-dipropylamino-6-methyl-7-aniline fluorane, 2-methyl-6-p-(p-dimethylaminophenyl)aminoaniline fluorane, 2-methoxy-6-p-(p-dimethylaminophenyl)aminoaniline fluorane, 2-chloro-3-methyl-6-p-(p-phenylaminophenyl)aminoaniline fluorane, 2-chloro-6-p-(p-dimethylaminophenyl)aminoaniline fluorane, 2-nitro-6-p-(p-diethylaminophenyl)aminoaniline fluorane, 2-amino-6-p-(p-diethylaminophenyl)aminoaniline fluorane, 2-diethylamino-6-p-(p-diethylaminophenyl)aminoaniline fluorane Ethylaminophenyl)aminoaniline fluorane, 2-phenyl-6-methyl-6-p-(p-phenylaminophenyl)aminoaniline fluorane, 2-benzyl-6-p-(p-phenylaminophenyl)aminoaniline fluorane, 2-hydroxy-6-p-(p-phenylaminophenyl)aminoaniline fluorane, 3-methyl-6-p-(p-dimethylaminophenyl)aminoaniline fluorane, 3-diethylamino-6-p-(p-diethylaminophenyl)aminoaniline fluorane, 3-diethylamino-6-p-(p-dibutylaminophenyl)aminoaniline fluorane, 2,4-dimethyl-6-[(4-dimethylamino)aniline]-fluorane.

[0144] <Fluorene-based leuco dyes>

[0145] 3,6,6'-Tris(dimethylamino)spiro[fluorene-9,3'-phthalide], 3,6,6'-Tris(diethylamino)spiro[fluorene-9,3'-phthalide].

[0146] <Divinyl leuco dyes>

[0147] 3,3-Bis-[2-(p-dimethylaminophenyl)-2-(p-methoxyphenyl)vinyl]-4,5,6,7-tetrabromophthalide, 3,3-Bis-[2-(p-dimethylaminophenyl)-2-(p-methoxyphenyl)vinyl]-4,5,6,7-tetrachlorophthalide, 3,3-Bis-[1,1-bis(4-pyrrolidinylphenyl)ethylene-2-yl]-4,5,6,7-tetrabromophthalide, 3,3-Bis-[1-(4-methoxyphenyl)-1-(4-pyrrolidinylphenyl)ethylene-2-yl]-4,5,6,7-tetrachlorophthalide.

[0148] <Other>

[0149] 3-(4-Diethylamino-2-ethoxyphenyl)-3-(1-ethyl-2-methylindole-3-yl)-4-azaphthalide, 3-(4-diethylamino-2-ethoxyphenyl)-3-(1-octyl-2-methylindole-3-yl)-4-azaphthalide, 3-(4-cyclohexylethylamino-2-methoxyphenyl)-3-(1-ethyl-2-methylindole-3-yl)-4-azaphthalide, 3,3-bis(1-ethyl-2-methylindole-3-yl)phthalide, 3,6-bis(diethylamino)fluorane-γ-(3'-nitro)anilinolactam, 3,6-bis(di-) Ethylamino)fluorane-γ-(4'-nitro)anilinolactam, 1,1-bis-[2',2',2",2"-tetra-(p-dimethylaminophenyl)-vinyl]-2,2-dionitrile ethane, 1,1-bis-[2',2',2",2"-tetra-(p-dimethylaminophenyl)-vinyl]-2-β-naphthoyl ethane, 1,1-bis-[2',2',2",2"-tetra-(p-dimethylaminophenyl)-vinyl]-2,2-diacetyl ethane, bis-[2,2,2',2'-tetra-(p-dimethylaminophenyl)-vinyl]-dimethylmalonate.

[0150] As the sensitizer used in this invention, conventionally known sensitizers can be used. Examples of such sensitizers include stearamide, palmitamide and other fatty acid amides, ethylene diamide, lignite wax, polyethylene wax, 1,2-bis-(3-methylphenoxy)ethane, p-benzylbiphenyl, β-benzyloxynaphthalene, 4-biphenyl-p-tolyl ether, m-terphenyl, 1,2-diphenoxyethane, dibenzyl oxalate, di(p-chlorobenzyl) oxalate, di(p-methylbenzyl) oxalate, dibenzyl terephthalate, benzyl p-benzyloxybenzoate, and di-p-toluene carbonate. Esters, phenyl-α-naphthyl carbonate, 1,4-diethoxynaphthalene, phenyl 1-hydroxy-2-naphthoic acid ester, o-xylene-bis(phenyl ether), 4-(m-methylphenoxymethyl)biphenyl, dibenzyl 4,4'-ethylenedioxy-bisbenzoate, dibenzoyloxymethane, 1,2-di(3-methylphenoxy)ethylene, bis[2-(4-methoxy-phenoxy)ethyl] ether, methyl p-nitrobenzene, phenyl p-toluenesulfonate, o-toluenesulfonamide, p-toluenesulfonamide, etc. These sensitizers can be used alone or in combination of two or more.

[0151] Examples of pigments used in this invention include kaolin, calcined kaolin, calcium carbonate, alumina, titanium dioxide, magnesium carbonate, aluminum silicate, magnesium silicate, calcium silicate, aluminum hydroxide, and silicon dioxide. These can also be used in combination depending on quality requirements.

[0152] Examples of binders used in this invention include fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, acetylated polyvinyl alcohol, carboxyl-modified polyvinyl alcohol, amide-modified polyvinyl alcohol, sulfonic acid-modified polyvinyl alcohol, butyral-modified polyvinyl alcohol, olefin-modified polyvinyl alcohol, nitrile-modified polyvinyl alcohol, pyrrolidone-modified polyvinyl alcohol, silicone-modified polyvinyl alcohol, other modified polyvinyl alcohols, hydroxyethyl cellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, styrene-maleic anhydride copolymer, styrene-butadiene copolymer, and cellulose derivatives such as ethyl cellulose and acetyl cellulose, casein, gum arabic, oxidized starch, etherified starch, dialdehyde starch, esterified starch, polyvinyl chloride, polyvinyl acetate, polyacrylamide, polyacrylate, polyvinyl butyral, polystyrene and its copolymers, polyamide resins, silicone resins, petroleum resins, terpene resins, ketone resins, coumarone resins, etc. These polymers can be used not only in solvents such as water, alcohols, ketones, esters, and hydrocarbons, but also in emulsified or dispersed into a paste state in water or other media. They can also be used in combination depending on quality requirements.

[0153] Examples of lubricants used in this invention include fatty acid metal salts such as zinc stearate and calcium stearate, waxes, and silicone resins.

[0154] In this invention, without impairing the desired effects on the aforementioned problems, as stabilizers to improve the oil resistance of the image section, 4,4'-butidene (6-tert-butyl-3-methylphenol), 2,2'-di-tert-butyl-5,5'-dimethyl-4,4'-dihydroxydiphenyl sulfone, 1,1,3-tris(2-methyl-4-hydroxy-5-cyclohexylphenyl)butane, 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, etc., may be added. Furthermore, benzophenone-based and triazole-based ultraviolet absorbers, dispersants, defoamers, antioxidants, fluorescent dyes, etc., may be used.

[0155] The types and amounts of leuco dyes, developers, sensitizers, and other components used in the thermal recording layer of this invention can be determined according to the required performance and recording suitability, and are not particularly limited. However, generally, relative to 1 part by weight of leuco dye, approximately 0.5 to 10 parts by weight of developer, 0.1 to 10 parts by weight of sensitizer, 0.5 to 20 parts by weight of pigment, 0.01 to 10 parts by weight of stabilizer, and 0.01 to 10 parts by weight of other components are used. A binder of approximately 5 to 25% by weight in the solid components of the thermal recording layer is appropriate.

[0156] In this invention, the leuco dye, color developer, and other materials added as needed are micronized using a ball mill, grinder, sand mill, or other pulverizer or a suitable emulsification device until the particle size becomes less than a few micrometers. A binder and various additives, depending on the purpose, are then added to prepare a coating liquid. Water or alcohol, etc., can be used as the solvent in this coating liquid, with a solid content of approximately 20-40% by weight.

[0157] Alternatively, the thermal recorder of the present invention may also have an adhesive layer disposed on a surface opposite to the surface of the support on which the thermal recording layer is disposed, thereby forming a thermal recording tag.

[0158] As the adhesive that constitutes the adhesive layer, it is suitable to use an adhesive that is water-soluble or water-redispersible, and water-soluble acrylic adhesives are particularly suitable.

[0159] Examples of water-soluble acrylic adhesives include substances containing copolymers as the base polymer: copolymers containing alkoxyalkyl acrylates, styrene sulfonates, and other copolymerizable monomers; copolymers of vinyl monomers containing carboxyl groups, such as (meth)acrylic acid, monomers containing hydroxyl groups, and other monomers capable of copolymerization, as appropriate. Examples of water-redispersible acrylic adhesives include substances containing copolymers as the base polymer: copolymers of alkyl methacrylates, vinyl monomers containing carboxyl groups, vinyl monomers with alkoxy groups, and other monomers capable of copolymerization, as appropriate; copolymers of vinyl monomers containing carboxylated rosin esters, vinyl monomers containing carboxyl groups, and water-soluble vinyl monomers. It should be noted that, depending on the need, some or all of the carboxyl groups in these copolymers may be salts neutralized with an alkali, such as alkali metal salts, amine salts, or alkanolamine salts.

[0160] In this water-soluble acrylic adhesive, a crosslinking agent can be added to adjust the adhesion, water solubility, or water dispersibility. There are no particular limitations on the type of crosslinking agent; any type can be appropriately selected from those conventionally used as crosslinking agents in conventional acrylic adhesives. Examples include isocyanate crosslinking agents such as 1,2-ethylene diisocyanate, epoxy crosslinking agents such as diglycidyl ethers, melamine resins, urea resins, dialdehydes, hydroxymethyl polymers, metal chelate compounds, metal alkoxides, and metal salts. Furthermore, in the aforementioned acrylic adhesive, to adjust the properties and improve performance as needed, conventionally known plasticizers, adhesion promoters, colorants, thickeners, defoamers, leveling agents, plasticizers, fungicides, and antioxidants can be appropriately added. Among them, plasticizers and adhesives are preferably water-soluble or water-dispersible. Examples of plasticizers include polyols such as sugar alcohols, polyether polyols, and alkanolamine salts of oxidized rosin. Examples of adhesives include alkali metal salts, ammonium salts, and polyether esters of rosin, disproportionated rosin, and hydrogenated rosin.

[0161] In the thermal recorder of the present invention, a protective layer may be further provided on the thermal recording layer. The protective layer is mostly composed of pigments and resins, and binders, pigments, crosslinking agents, etc., which are examples of materials that can be used in thermal recording layers, can be used.

[0162] As such an adhesive, an adhesive suitable for use in the aforementioned thermal recording layer may be appropriately used, but carboxyl-modified polyvinyl alcohol and non-core-shell acrylic resins are preferred. One or more of these adhesives may be used.

[0163] In addition, crosslinking agents that can be used in the above-mentioned thermosensitive recording layer can be used as appropriate, but epichlorohydrin-based resins and polyamine / polyamide-based resins (excluding the resin contained in epichlorohydrin-based resins) are preferred.

[0164] The protective layer preferably contains both carboxyl-modified polyvinyl alcohol and epichlorohydrin resin as well as polyamine / polyamide resin, which can further improve the color performance.

[0165] This carboxyl-modified polyvinyl alcohol can be obtained as a reactant of polyvinyl alcohol with polycarboxylic acids such as fumaric acid, phthalic anhydride, hexacarboxylic anhydride, and itaconic anhydride, or an esterified product of such reactants, or a saponified product of a copolymer formed by vinyl acetate with olefinically unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, crotonic acid, acrylic acid, and methacrylic acid. Specific manufacturing methods can be exemplified by, for example, those shown in Japanese Patent Application Publication No. 53-91995. Furthermore, the degree of saponification of the carboxyl-modified polyvinyl alcohol is preferably 72–100 mol%, and the degree of polymerization is 500–2400, more preferably 1000–2000.

[0166] The glass transition temperature (Tg) of this non-core-shell acrylic resin is preferably below 95°C, and more preferably above 50°C. This Tg is determined using differential scanning calorimetry (DSC).

[0167] This non-core-shell acrylic resin comprises (meth)acrylic acid and monomeric components capable of copolymerizing with (meth)acrylic acid, wherein the (meth)acrylic acid is preferably 1 to 10 parts by weight per 100 parts by weight of the non-core-shell acrylic resin. (Meth)acrylic acid is alkali-soluble and has the characteristic of making the non-core-shell acrylic resin a water-soluble resin by adding a neutralizing agent. By converting the non-core-shell acrylic resin into a water-soluble resin, especially when the protective layer contains pigments, the binding affinity to pigments is significantly improved, and a protective layer with excellent strength can be formed even when a large amount of pigment is present. Examples of components capable of copolymerizing with (meth)acrylic acid include, for example, alkyl acrylate resins such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, isobutyl methacrylate, pentyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, and octyl methacrylate, as well as epoxy resins, silicone resins, modified alkyl acrylate resins such as those modified with styrene and its derivatives, (meth)acrylonitrile, acrylates, and hydroxyalkyl acrylates. It is particularly preferred to combine (meth)acrylonitrile with / or methyl methacrylate. Preferably, 15 to 70 parts of (meth)acrylonitrile are incorporated into 100 parts of a non-core-shell acrylic resin. Furthermore, it is preferable to include 20 to 80 parts of methyl methacrylate in 100 parts of the non-core-shell acrylic resin. In the case of (meth)acrylonitrile and methyl methacrylate, it is preferable to add 15 to 18 parts of (meth)acrylonitrile to 100 parts of non-core-shell acrylic resin and 20 to 80 parts of methyl methacrylate to 100 parts of non-core-shell acrylic resin.

[0168] This epichlorohydrin resin is characterized by containing epoxy groups in its molecule. Examples include polyamide epichlorohydrin resin and polyamine epichlorohydrin resin, which can be used alone or in combination. Furthermore, the amine present on the main chain of the epichlorohydrin resin can range from primary amines to quaternary ammonium amines, without particular limitation. Moreover, for excellent water resistance, the preferred cationic degree and molecular weight are: cationic degree ≤ 5 meq / g·Solid (measured at pH 7) and molecular weight ≥ 500,000. Specific examples of epichlorohydrin resins include Sumirez Resin 650(30), Sumirez Resin 675A, Sumirez Resin 6615 (all manufactured by Sumitomo Chemical Co., Ltd.), WS4002, WS4020, WS4024, WS4030, WS4046, WS4010, and CP8970 (all manufactured by Starlight PMC Co., Ltd.).

[0169] The polyamine / polyamide resin does not contain epoxy groups in its molecule. Examples include polyamide urea resin, polyalkylene polyamine resin, polyalkylene polyamide resin, polyamine polyurea resin, modified polyamine resin, modified polyamide resin, polyalkylene polyamine urea-formaldehyde resin, polyalkylene polyamine polyamide polyurea resin, etc. These can be used alone or in combination. Specific examples of polyamine / polyamide resins include: Sumirez Resin 302 (manufactured by Sumitomo Chemical Co., Ltd.: polyamine polyurea resin), Sumirez Resin 712 (manufactured by Sumitomo Chemical Co., Ltd.: polyamine polyurea resin), Sumirez Resin 703 (manufactured by Sumitomo Chemical Co., Ltd.: polyamine polyurea resin), Sumirez Resin 636 (manufactured by Sumitomo Chemical Co., Ltd.: polyamine polyurea resin), Sumirez Resin SPI-100 (manufactured by Sumitomo Chemical Co., Ltd.: modified polyamine resin), Sumirez Resin SPI-102A (manufactured by Sumitomo Chemical Co., Ltd.: modified polyamine resin), Sumirez Resin SPI-106N (manufactured by Sumitomo Chemical Co., Ltd.: modified polyamide resin), Sumirez Resin SPI-203(50) (manufactured by Sumitomo Chemical Co., Ltd.), Sumirez Resin SPI-198 (manufactured by Sumitomo Chemical Co., Ltd.), Printive A-700, Printive A-600 (manufactured by Asahi Kasei Corporation), PA6500, PA6504, PA6634, PA6638, PA6640, PA6644, PA6646, PA6654, PA6702, PA6704 (manufactured by Starlight PMC Corporation: polyalkylene polyamine polyamide polyurea resin), CP8994 (manufactured by Starlight PMC Corporation: polyethylene imine resin), etc. There are no particular restrictions, but for excellent print density, polyamine resins (polyalkylene polyamine resin, polyamine polyurea resin, modified polyamine resin, polyalkylene polyamine urea-formaldehyde resin, polyalkylene polyamine polyamide polyurea resin) are preferred.

[0170] Regarding the content of epichlorohydrin resin and polyamine / polyamide resin in the protective layer when using carboxyl-modified polyvinyl alcohol, it is preferably 1 to 100 parts by weight, more preferably 5 to 50 parts by weight, and even more preferably 10 to 40 parts by weight, relative to 100 parts by weight of carboxyl-modified polyvinyl alcohol.

[0171] As pigments used in the protective layer, pigments suitable for use in the aforementioned thermal recording layer may be appropriately used, but kaolin, calcined kaolin, aluminum hydroxide, and silica are preferred. One or more of these pigments may be used.

[0172] The content of binder (solid component) in the protective layer is preferably 20% by weight or more, more preferably about 20 to 80% by weight. When the protective layer contains pigment, the content of pigment and binder is preferably about 30 to 300 parts by weight of binder as solid component relative to 100 parts by weight of pigment.

[0173] The coating liquid for the protective layer may also be appropriately mixed with various additives such as crosslinking agents, lubricants, stabilizers, ultraviolet absorbers, dispersants, defoamers, antioxidants, and fluorescent dyes that can be used in the above-mentioned thermal recording layers, as needed.

[0174] By applying a coating liquid containing the components of the formulations used for each of the above coating layers onto a support, a thermal recorder can be obtained. Alternatively, a composite sheet obtained by combining these components can also be used as a support.

[0175] Electron-donating leuco dyes, electron-accepting color developers, electron acceptors, electron donors, and other materials added as needed are micronized using pulverizers such as ball mills, grinders, sand mills, or appropriate emulsification devices until the particle size becomes less than a few micrometers, and various additives are added according to the purpose to prepare a coating liquid.

[0176] There are no particular limitations on the method of applying the above coating layer; it can be performed according to well-known and commonly used techniques. For example, appropriate post-coating machines or on-machine coating machines equipped with various coating machines such as air knife coating machines, bar blade coating machines, curved blade coating machines, angled blade coating machines, roller coating machines, curtain coating machines, and spray coating machines can be selected. The coating amount of the thermal recording layer is determined according to the required performance and recording suitability, and there are no particular limitations, but the typical coating amount is 2 to 12 g / m³ based on the solid component. 2 about.

[0177] In addition, after each coating layer is applied, various well-known techniques in the field of thermal recording materials can be appropriately added, such as the implementation of smoothing treatments such as supercalendering.

[0178] Example

[0179] The present invention is illustrated below by way of examples, but is not intended to limit the scope of the invention. It should be noted that, unless otherwise specified, in the various embodiments and comparative examples, "parts" means "parts by weight" and "%" means "% by weight".

[0180] The color developer dispersion (A1-A4), leuco dye dispersion (B), and sensitizer dispersion (C) were each wet-milled using a sand mill until the average particle size became 1.0 μm.

[0181] Colorimetric reagent dispersion (A1 solution)

[0182]

[0183] Colorimetric reagent dispersion (A2 solution)

[0184]

[0185]

[0186] Colorimetric reagent dispersion (A3 solution)

[0187]

[0188] Colorimetric reagent dispersion (A4 solution)

[0189]

[0190] Leuco dye dispersion (solution B)

[0191]

[0192] Sensitizer dispersion (C solution)

[0193]

[0194] Next, the dispersions are mixed in the following ratios to prepare a coating for a thermal recording layer.

[0195] <Coatings for Thermal Recording Layers 1>

[0196] Colorimetric reagent dispersion (A1 solution) 36.0 parts

[0197] Leuco dye dispersion (solution B) 9.2 parts

[0198] Sensitizer dispersion (C solution) 12.0 parts

[0199] <Coatings for Thermal Recording Layers 2>

[0200]

[0201] Next, the adhesive coating with the following formulation is prepared.

[0202] <Adhesives and Coatings>

[0203]

[0204] Example 1

[0205] To produce a three-layer handmade paper, an inner layer and a surface layer formed on both sides of the inner layer are laminated in a weight ratio of surface layer:inner layer:surface layer = 1:4:1. The inner layer is formed from papermaking raw material made by beating a mixed pulp to a Canadian standard freeness of 675 ml CSF. This mixed pulp contains 70 wt% bleached softwood sulfate pulp (α-cellulose content 85.6 wt%) as wood pulp and 30 wt% hardwood dissolving pulp (α-cellulose content 98.3 wt%) as refined pulp. The surface layer is made from a mixed pulp beaten to a Canadian standard freeness of 500 ml CSF. CSF's papermaking raw material is formed by combining 15% by weight of bleached softwood sulfate pulp (85.6% by weight of α-cellulose) and 55% by weight of bleached hardwood sulfate pulp (86.0% by weight of α-cellulose) as wood pulp, and 30% by weight of hardwood dissolving pulp (98.3% by weight of α-cellulose) as refined pulp. The paper surface pH is 6.7.

[0206] On this handmade paper, an aqueous solution (pH 7.1) of sodium carboxymethyl cellulose (CMC-Na, manufactured by Nippon Paper Corporation, trade name: Sunrose, with a viscosity of 5 mPa·s at 20°C for a 2% by weight aqueous solution) (hereinafter also referred to as "CMC-Na"), which is a water-soluble polymer, is sized and pressed at 8% by weight relative to the handmade paper to produce a water-dispersible sheet (base paper).

[0207] The thermal recording layer, coated with coating 1, is applied to the surface of the base paper (hereinafter also referred to as the "second surface layer") at a concentration of 6 g / m². 2 The coating is applied in a specific manner and dried (at 50°C) to form a thermal recording layer, resulting in thermal recording paper. This thermal recording paper is then smoothed using a Beck smoothness setting of 500–1000 seconds.

[0208] A portion of the obtained thermal recording paper is reserved for the evaluation described later, while the remaining thermal recording paper is processed further.

[0209] The above-mentioned adhesive coating was applied to the peeling surface of a commercially available release sheet coated with silicone release agent at a concentration of 25 g / m² (solid content). 2 The adhesive layer is applied and dried to form an adhesive layer. This adhesive layer is then bonded to the surface of the thermal recording paper opposite to the thermal recording layer (first surface layer) to create a water-dispersible thermal recording label.

[0210] Example 2

[0211] Except for changing thermal recording layer coating 1 to thermal recording layer coating 2, the same operation as in Example 1 was performed to produce thermal recording paper and thermal recording label.

[0212] Example 3

[0213] Except for changing the color developer dispersion (A1 liquid) of the thermal recording layer coating 1 to the color developer dispersion (A2 liquid), the same operation as in Example 1 was performed to produce thermal recording paper and thermal recording label.

[0214] Comparative Example 1

[0215] Except for changing the color developer dispersion (A1 liquid) of the thermal recording layer coating 1 to the color developer dispersion (A3 liquid), the same operation as in Example 1 was performed to produce thermal recording paper and thermal recording label.

[0216] Comparative Example 2

[0217] For the base paper, a three-layer handmade paper is made by laminating one surface layer on each side of a single inner layer in a weight ratio of surface layer:inner layer:surface layer = 1:2:1, and then stacking the inner and surface layers. The inner layer is formed from a papermaking raw material consisting of 67 parts by weight of pulp beaten to a Canadian standard freeness of 670 ml CSF, combined with 33 parts by weight of fibrous carboxymethyl cellulose (CMC-CB manufactured by Nichirin Chemical Industries, Inc., etherification degree 0.43) (hereinafter referred to as "CMC"). This pulp contains 15% by weight of bleached softwood sulfate pulp and 85% by weight of bleached hardwood sulfate pulp. The surface layer is formed from a papermaking raw material consisting of 67 parts by weight of pulp beaten to a Canadian standard freeness of 500 ml CSF, combined with 33 parts by weight of fibrous carboxymethyl cellulose (the same as above). For this handmade paper, a base paper is prepared by impregnating and coating a 2.5% by weight aqueous solution of sodium carbonate (Soda Ash Light manufactured by Tokuyama Corporation) at a weight of 10% by weight relative to the handmade paper by sizing and pressing.

[0218] In this regard, except that the color developer dispersion (A1 liquid) of the thermal recording layer coating 1 is changed to the color developer dispersion (A3 liquid), the same operation as in Example 1 is performed to produce thermal recording paper and thermal recording label.

[0219] Comparative Example 3

[0220] Except for not sizing and pressing sodium carboxymethyl cellulose (CMC-Na), the same procedures as in Example 1 were performed to produce thermal recording paper and thermal recording labels.

[0221] Comparative Example 4

[0222] Except for changing the developer dispersion (A1 liquid) of the thermal recording layer coating 1 to the developer dispersion (A2 liquid), the same operation as in Comparative Example 3 was performed to produce thermal recording paper and thermal recording label.

[0223] Reference Example 1

[0224] Except for changing the developer dispersion (A1 liquid) of the thermal recording layer coating 1 to the developer dispersion (A4 liquid), the same operation as in Comparative Example 1 was performed to produce thermal recording paper and thermal recording label.

[0225] The following evaluation is performed on the prepared thermal recording paper.

[0226] <Color rendering performance (print density)>

[0227] For the prepared thermal recording paper, a checkerboard pattern was printed using the TH-PMD (thermal recording paper printing test machine, equipped with a Kyocera thermal head) manufactured by Okura Electric Co., Ltd., at a printing speed of 50 mm / sec and an applied energy of 0.41 mJ / dot. The printing density of the printed section was measured using a Macbeth density meter (RD-914, using an amber color filter), and the color rendering performance (printing density) was evaluated.

[0228] <Reprintability> (Color sensitivity after saving)

[0229] The prepared thermal recording paper was stored at 40°C and 90% RH for 96 hours. Printing was then performed on the stored thermal recording paper using an TH-PMD (thermal recording paper printing tester, equipped with a Kyocera thermal head) manufactured by Okura Electric Co., Ltd., at an applied energy of 0.27 mJ / dot and a printing speed of 50 mm / sec. The print density of the full-page print area was measured using a Macbeth density meter (RD-914, using an amber filter) to evaluate the color sensitivity after storage.

[0230] <Resistance to damp heat>

[0231] For the prepared thermal recording paper, a checkerboard pattern was printed using the TH-PMD (thermal recording paper printing tester, equipped with a Kyocera thermal head) manufactured by Okura Electric Co., Ltd., under conditions of applied energy of 0.41 mJ / dot and a printing speed of 50 mm / sec. After the printed thermal recording paper was placed in an environment of 40°C and 50% RH for 24 hours, the printing density of the printed area was measured using a Macbeth density meter (RD-914, using an amber filter). The residual rate was calculated based on the values ​​before and after treatment to evaluate the resistance to damp heat.

[0232] Residual rate (%) = (Print density of the printed section after treatment / Print density of the printed section before treatment) × 100

[0233] Excellent: The survival rate is over 90%.

[0234] Acceptable: The survival rate is above 70% but less than 90%.

[0235] Not allowed: Survival rate less than 70%.

[0236] <Plasticizer Resistance>

[0237] For the prepared thermal recording paper, a checkerboard pattern was printed using the TH-PMD (thermal recording paper printing test machine, equipped with a thermal head manufactured by Kyocera) manufactured by Okura Electric Co., Ltd., under the conditions of applying energy of 0.41mJ / dot and printing speed of 50mm / sec.

[0238] Wrap one layer of polyvinyl chloride (PVC) cling film (Mitsui Chemicals Hi-wrap KMA) around a paper tube, attach a printed thermal recording paper, and then wrap three more layers of PVC cling film around it. Let it stand for 24 hours at 23°C and 50% RH.

[0239] The printing density of the printing section was measured using a Macbeth density meter (RD-914, with an amber filter), and the residual rate was calculated based on the values ​​before and after treatment to evaluate plasticizer resistance.

[0240] Residual rate (%) = (Print density of the printed section after treatment / Print density of the printed section before treatment) × 100

[0241] Excellent: The survival rate is over 70%.

[0242] Acceptable: The survival rate is above 50% but less than 70%.

[0243] Not allowed: Survival rate less than 50%.

[0244] Solvent resistance

[0245] Apply ethanol (99.5%) to the white portion of the prepared thermal recording paper with a cotton swab, let it stand for 24 hours at 23°C and 50% RH, and then perform a visual evaluation according to the following criteria.

[0246] Excellent: It does not show any color at all.

[0247] Slight coloration.

[0248] Not suitable for strong coloring.

[0249] For the prepared thermal recording paper, the following evaluation was conducted 14 days after the adhesive coating was applied and the paper was stored at room temperature (23°C, 50% RH). It should be noted that the evaluation was performed after the release liner was removed during the water dispersibility test.

[0250] <Water-soluble>

[0251] Five 3cm square test pieces were prepared using thermal recording paper. Then, 300ml of deionized water was added to a 300ml beaker, and one test piece was added while stirring at 650rpm. The time it took for the test piece to disperse into individual fibers was measured using a stopwatch. A test piece was considered water-soluble if the average of the five measurements was less than 300 seconds, and not water-soluble if it exceeded 300 seconds.

[0252] In addition, the following evaluation is performed on the produced thermal recording tags.

[0253] <Water dispersibility>

[0254] Five 3cm square test pieces were prepared using thermal recording paper. Then, 300ml of deionized water was added to a 300ml beaker, and one test piece was added while stirring at 650rpm. The test piece was torn into at least two pieces, and the time it took to form flocculated material was measured using a stopwatch. The average of the five measurements was taken as the water dispersion time. It should be noted that a shorter water dispersion time indicates better water dispersibility.

[0255] <Adhesion>

[0256] Based on JIS Z0237, three strips of test piece with a width of 25mm and a length of 250mm were cut out, the release paper was peeled off, and the adhesive-coated side was placed on a stainless steel plate (100×150mm). A rubber roller weighing 3kg was rolled back and forth twice to press the strips together.

[0257] The stainless steel plate is clamped in the lower chuck of the tensile testing machine. One end of the sample to be bonded is folded 180° and clamped in the upper chuck. A 180° tensile peel test is performed at a tensile speed of 300 mm / min, and the adhesive force (g / 25 mm) is measured. If the adhesive force on the 14th day is more than 60% of the initial adhesive force (day 1), the adhesion over time can be judged to be good.

[0258] Image quality (print quality)

[0259] Fourteen days after the thermal recording labels were manufactured, grayscale printing was performed on the thermal recording layer using an TH-PMD (thermal recording paper printing tester, equipped with a Kyocera thermal head) manufactured by Okura Electric Co., Ltd., with applied energy ranging from 0.150 mJ / dot to 0.345 mJ / dot, increasing by 0.015 mJ / dot each time. The fineness of the printed area within this range was visually evaluated, and the print quality was evaluated according to the following criteria. It can be said that the better the print quality, the better the surface of the thermal recording paper (second surface layer).

[0260] Advantage: It can print without uneven printing.

[0261] Good: Almost no printing unevenness.

[0262] Yes: There is some uneven printing, but it is within the acceptable range.

[0263] No: A considerable amount of blank space can be seen in the printout.

[0264] The results are shown in the table below.

[0265] [Table 1]

[0266]

Claims

1. A thermal recording tag comprising a thermal recording layer on a support containing a colorless or light-colored electron-donating leuco dye and an electron-accepting color developer, and an adhesive layer disposed on a surface opposite to the surface of the support on which the thermal recording layer is disposed, wherein the thermal recording layer contains at least one urea compound represented by the general formula of the following chemical formula 1 as an electron-accepting color developer. Chemical Formula 1 In chemical formula 1, X represents -O- or -NH-, R 1 Represents a hydrogen atom or -SO2-R 3 R 3 Indicates substituted or unsubstituted alkyl, aralkyl, or aryl groups, R 2 This indicates a hydrogen atom or an alkyl group, where m represents 0 or 1. The support comprises a water-dispersible paper substrate. The thermal recording tag has a water dispersion time of less than 8.1 seconds. in, Regarding the water dispersion time, five 3cm square test pieces were prepared using the sample of the thermal recording tag. Then, 300ml of deionized water was added to a 300ml beaker. While stirring with a stirrer at 650rpm, one test piece was added. The time it took for the test piece to be torn into more than two pieces and become flocculent was measured with a stopwatch. The average value of the five measurements was taken as the water dispersion time.

2. The thermal recording tag according to claim 1, wherein, The paper substrate is any one of the following (1) to (3): (1) A paper substrate comprising an inner layer and two surface layers disposed on both sides of the inner layer, each surface layer being independently formed of a mixed pulp comprising wood pulp and refined pulp having an α-cellulose content of 88% by weight or more, the mixed pulp having a Canadian standard freeness of 450 ml to 600 ml CSF, and the wood pulp content in the mixed pulp being 50% by weight to 95% by weight; the inner layer being formed of a second mixed pulp comprising wood pulp and refined pulp having an α-cellulose content of 88% by weight or more, the second mixed pulp having a Canadian standard freeness of 600 ml to 750 ml CSF, and the wood pulp content in the second mixed pulp being 50% by weight to 95% by weight. (2) A paper substrate comprising an inner layer and two surface layers respectively disposed on both sides of the inner layer, the inner layer comprising papermaking fibers with a Canadian standard freeness of 600 ml to 750 ml CSF and alkalized fibrous carboxymethyl cellulose, each of the surface layers independently comprising papermaking fibers and alkalized fibrous carboxymethyl cellulose, wherein the papermaking fibers in at least one surface layer have a Canadian standard freeness of 400 ml to 575 ml CSF, and the content of the papermaking fibers is 60% to 90% by mass. (3) A paper substrate comprising papermaking fibers and alkalized fibrous carboxyalkyl cellulose, and further comprising a carboxyalkyl cellulose salt, wherein the degree of etherification of the fibrous carboxyalkyl cellulose is 0.2 to 0.6, the degree of etherification of the carboxyalkyl cellulose salt is 0.5 to 1.6, the viscosity of a 1% by weight aqueous solution of the carboxyalkyl cellulose salt measured by a Brookfield viscometer is 2 mPa•s to 200 mPa•s, and the proportion of the carboxyalkyl cellulose salt is 0.1% to 10% by weight relative to the total of the papermaking fibers and the alkalized fibrous carboxyalkyl cellulose.

3. The thermal recording tag according to claim 1 or 2, wherein, The urea compound is either (1) or (2) below: (1) A first urea compound represented by the general formula 2 below, Chemical formula 2 In chemical formula 2, R 1 R 2 and R 3 Same as the definition described above; (2) The second urea compound represented by the following chemical formula 3 Chemical formula 3 In chemical formula 3, R 2 As defined above, R 4 ~R 8 Each may be the same or different, representing a hydrogen atom, halogen atom, nitro group, amino group, alkyl group, alkoxy group, aryloxy group, alkyl carbonyloxy group, aryl carbonyloxy group, alkyl carbonyl amino group, aryl carbonyl amino group, alkyl sulfonyl amino group, aryl sulfonyl amino group, monoalkyl amino group, dialkyl amino group, or aryl amino group.

4. The thermal recording tag according to claim 3, wherein, The first urea compound is represented by the general formula of the following chemical formula 4: Chemical Formula 4 In chemical formula 4, R 2 As defined above, R 3 Each may be the same or different, and is a group represented by the following chemical formula 5, where R in the benzene ring of the general formula 4 is... 3 The positions of -SO2-O- may be the same or different, and may be 3, 4 or 5 positions. Chemical Formula 5 In chemical formula 5, R 4 ~R 8 Each may be the same or different, representing a hydrogen atom, halogen atom, nitro group, amino group, alkyl group, alkoxy group, aryloxy group, alkyl carbonyloxy group, aryl carbonyloxy group, alkyl carbonyl amino group, aryl carbonyl amino group, alkyl sulfonyl amino group, aryl sulfonyl amino group, monoalkyl amino group, dialkyl amino group, or aryl amino group.

5. The thermal recording tag according to claim 3, wherein, The first urea compound is represented by the general formula of the following chemical formula 6: Chemical Formula 6 In chemical formula 6, R 9 Each can be the same or different, indicating alkyl or alkoxy groups, with o representing an integer from 0 to 3.

6. The thermal recording tag according to claim 5, wherein, In the first urea compound, R 9 The symbol represents an alkyl group with 1 to 4 carbon atoms, and 'o' represents an integer from 0 to 1. The 'R' in the benzene ring... 9 The position is 4.

7. The thermal recording tag according to claim 3, wherein, The second urea compound is N-[2-(3-phenylureo)phenyl]benzenesulfonamide.

8. The thermal recording tag according to claim 1 or 2, wherein, The content of urea compounds in the thermal recording layer, based on solid components, is 1.0% to 70.0% by weight.

9. The thermal recording tag according to claim 3, wherein, The thermal recording layer contains color developers other than the first urea compound and the second urea compound, and the total content of the first urea compound and the second urea compound, based on solid components, is 90% or more relative to all color developers contained in the thermal recording layer.

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