JP2540297C - - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a heat-sensitive recording material, and more particularly, to a heat-sensitive recording material having improved heat sensitivity and head matching. [Prior Art] Demand for heat-sensitive recording materials is rapidly expanding as a recording material that is inexpensive and easy to maintain a recording machine. However, recently, facsimile machines, printers, per code labels, etc., can record clear images at high density even with a small amount of energy due to high speed, and the reliability of the obtained images, such as oils and fats such as fingerprints and plastic erasers, There is no discoloration or coloring due to plasticizers and whiskey, sake, alcohol such as shochu, etc. contained in mending tapes, salted pilaps, etc. Furthermore, there is no head matching property, for example, no sticking, head residue, no head wear, etc. Quality is required. In order to achieve high sensitivity, it is of course important to select the coloring material to be used, but the amount of fillers, binders, etc. used together is important, and it is necessary to minimize the use in the thermosensitive coloring layer. There is. However, when these are reduced, the reliability of the image and the head matching are deteriorated. Decoloration of images especially with oils and fats and plasticizers,
There is peeling or sticking of the layer due to water or alcohol. In order to improve this defect, it has been proposed to provide various overcoat layers on the thermosensitive coloring layer.
When the overcoat layer is provided, the heat-sensitive coloring layer comes into contact with the thermal head via the overcoat layer during printing, so that there is a disadvantage that heat conduction is inhibited and the coloring sensitivity is reduced. . Furthermore, in the conventionally known method of providing an overcoat layer, it is necessary to increase the ratio of a binder and a filler in order to prevent the penetration of oils and fats and a plasticizer into the heat-sensitive coloring layer, and as a result, sticking is reduced. In order to prevent this sticking, fillers have been used in the conventional method.However, depending on the type of filler, head abrasion may occur, or the binder may be hardened due to the inability to perform high-temperature treatment and sticking. There is a drawback that it takes a long time to improve. [Purpose] The present invention provides high-density color development at low energy without the above-mentioned difficulties, high oil resistance, high water-peeling resistance, high reliability of recorded images, and excellent head matching. To provide a heat-sensitive recording material. [Constitution] According to the present invention, in a heat-sensitive recording material comprising a support, a thermosensitive coloring layer containing a leuco dye and a developer, and an overcoat layer provided thereon, In addition, as a water-soluble polymer and a water-resistant agent, polyamide epichlorohydrin
20 to 70% by weight of a binder combined with a fat and aluminum hydroxide 5 as a filler
45% by weight, and the dry coating amount of the overcoat layer is 1.0 to 6.0 g /
m ² is provided. That is, the present invention provides a specific amount of a water-soluble polymer and a waterproofing agent as main components on the thermosensitive coloring layer.
In addition, a specific amount of overcoat layer using aluminum hydroxide as a filler and a binder combined with a polyamide epichlorohydrin resin is used to maintain high sensitivity, oil resistance, water peeling resistance, image reliability And improved head matching. The overcoat layer of the present invention functions as a layer that has little decrease in color-forming sensitivity, improves oil resistance, water resistance, reliability of a printed image, and improves head matching. In the present invention, as a binder used for the overcoat layer, polyvinyl alcohol, starch and derivatives thereof, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, cellulose derivatives such as ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylic acid Amide / acrylic ester copolymer, acrylamide / acrylic ester / methacrylic acid terpolymer, styrene / maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, water-soluble polymer and water-proofing agent of casein, poly
An amide epichlorohydrin resin is used in combination. That is, in the present invention, the amount of the constituent components of the overcoat layer is 20 to 70% by weight for the binder and 5 to 45% by weight for the aluminum hydroxide.
A preferable result can be obtained by adjusting the dry coating amount of the overcoat layer to 1.0 to 6.0 g / m ² . If the amount of the binder used is less than 20% by weight and the amount of aluminum hydroxide is more than 45% by weight, the prevention of penetration by oils and fats and plasticizers is insufficient, and the amount of the binder used is 7%.
If the amount is more than 0% by weight and the amount of aluminum hydroxide is less than 5% by weight, the time required to function as an overcoat layer is undesirably long. On the other hand, if the dry coating weight of the overcoat layer is less than 1.0 g / m ² , the effect of preventing oil resistance, water peeling resistance, sticking and the like becomes insufficient, and conversely, the dry coating weight becomes 6.0 g / m 2. ^If it exceeds ² , the dynamic color density decreases, and the intended object of the present invention cannot be achieved. The thermosensitive coloring layer of the present invention is mainly composed of a leuco dye and a color developer, and the leuco dye is applied alone or as a mixture of two or more kinds. What is applied to the heat-sensitive material is arbitrarily applied, and for example, a leuco compound of a dye such as triphenylmethane, fluoran, phenothiazine, auramine, spiropyran, or indolinophthalide is preferably used. Specific examples of such leuco dyes include, for example, those shown below. 3,3-bis (p-dimethylaminophenyl) -phthalide, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also known as crystal violet lactone), 3,3-bis (p- Dimethylaminophenyl) -6-diethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) -6-chlorophthalide, 3,3-bis (p-dibutylaminophenyl) phthalide, 3,3-cyclohexylamino- 6-chlorofluorane, 3-dimethylamino-5,7-dimethylfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluoran, 3-diethylamino-7,8-benzfluoran 3-diethylamino-6-methyl-7-chlorofluoran, 3- (NP-tolyl N-ethylamino) -6-methyl-7-anilinofluoran, 3-pyrrolidino-6-methyl-7-anilinofluoran, 2- {N- (3'-trifluoromethylphenyl) amino} -6 -Diethylaminofluoran, 2- {3,6-bis (diethylamino) -9- (o-chloroanilino) xanthylbenzoic acid lactam}, 3-diethylamino-6-methyl-7- (m-trichloromethylanilino) fluoran, 3-diethylamino-7- (o-chloroanilino) fluoran, 3-dibutylamino-7- (o-chloroanilino) fluoran, 3-N-methyl-N-amylamino-6-methyl-7-anilinofluoran, 3- N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl -7-anilinofluoran, 3- (N, N-diethylamino) -5-methyl-7- (N, N-dibenzylamino) fluoran, benzoylleucomethylene blue, 6'-chloro-8'-methoxy-benzoin Dorino-pyrrospirane, 6'-bromo-3'-methoxy-benzoindolino-pyrrospirane, 3- (2'-hydroxy-4'-dimethylaminophenyl) -3- (2'-methoxy-5'-chlorophenyl ) Phthalide, 3- (2'-hydroxy-4'-dimethylaminophenyl) -3- (2'-methoxy-5'-nitrophenyl) phthalide, 3- (2'-hydroxy-4'-diethylaminophenyl)- 3- (2'-methoxy-5'-methylphenyl) phthalide, 3- (2'-methoxy-4'-dimethylaminophenyl) -3- (2'-hydroxy-4 'Chloro-5'-methylphenyl) phthalide, 3-morpholino-7- (N-propyl-trifluoromethylanilino) fluoran, 3-pyrrolidino-7-trifluoromethylanilinofluoran, 3-diethylamino-5-chloro -7- (N-benzyl-trifluoromethylanilino) fluoran, 3-pyrrolidino-7- (di-p-chlorophenyl) methylaminofluoran, 3-diethylamino-5-chloro-7- (α-phenylethyl Amino) fluoran, 3- (N-ethyl-p-toluidino) -7- (α-phenylethylamino) fluoran, 3-diethylamino-7- (o-methoxycarbonylphenylamino) fluoran, 3-diethylamino-5-methyl -7- (α-phenylethylamino) fluoran, 3-diethylamino 7-piperidinofluoran, 2-chloro-3- (N-methyltoluidino) -7- (pn-butylanilino) fluoran, 3- (N-benzyl-N-cyclohexylamino) -5,6-benzo- 7-α
-Naphthylamino-4'-bromofluorane, 3-diethylamino-6-methyl-7-mesitidino-4 ', 5'-benzofluoran and the like. Further, as the developer used in the present invention, various electron-accepting substances that react with the leuco dye upon heating to develop the color are applied, and specific examples thereof include phenolic compounds as shown below. Substances, organic or inorganic acidic substances, and esters and salts thereof. Gallic acid, salicylic acid, 3-isopropylsalicylic acid, 3-cyclohexylsalicylic acid, 3,5-di-α-methylbenzylsalicylic acid, 4,4′-isopropylidenediphenol, 4,4′-isopropylidenebis (2-chlorophenol ), 4,4'-isopropylidenebis (2,6-dibromophenol), 4,4
'-Isopropylidenebis (2,6-dichlorophenol), 4,4'-isopropylidenebis (2-methylphenol), 4,4'-isopropylidenebis (2
, 6-dimethylphenol), 4,4'-isopropylidenebis (2-tert
-Butylphenol), 4,4'-sec-butylidenediphenol, 4,4 '
-Cyclohexylidenebisphenol, 4,4'-cyclohexylidenebis (2
-Methylphenol), 4-tert-butylphenol, 4-phenylphenol, 4-hydroxydiphenoxide, α-naphthol, β-naphthol, 3,
5-xylenol, thymol, methyl-4-hydroxybenzoate, 4-hydroxyacetophenone, novolak-type phenol resin, 2,2′-thiobis (4
, 6-dichlorophenol), catechol, resorcin, hydroquinone, pyrogallol, phloroglysin, phloroglysine carboxylic acid, 4-tert-octylcatechol, 2,2'-methylenebis (4-chlorophenol), 2,2'-methylenebis ( 4-methyl-6-tert-butylphenol), 2,2′-dihydroxydiphenyl, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate, butyl p-hydroxybenzoate, benzyl p-hydroxybenzoate,
p-hydroxybenzoic acid-p-chlorobenzyl, p-hydroxybenzoic acid-p-
Methylbenzyl, n-octyl p-hydroxybenzoate, benzoic acid, zinc salicylate, 1-hydroxy-2-naphthoic acid, 2-hydroxy-6-naphthoic acid,
Zinc 2-hydroxy-6-naphthoate, 4-hydroxydiphenylsulfone,
-Hydroxy-4'-chlorodiphenyl sulfone, bis (4-hydroxyphenyl) sulfide, 2-hydroxy-p-toluic acid, zinc 3,5-di-tert-butylsalicylate, 3,5-di-tert-butylsalicylic acid Tin, tartaric acid, oxalic acid, stearic acid, 4-hydroxyphthalic acid, boric acid and the like. In the present invention, in order to bond and support the leuco dye and the developer on a support, various conventional binders can be appropriately used, for example, polyvinyl alcohol, starch and its derivative, methoxycellulose, Cellulose derivatives such as hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide / acrylate copolymer, acrylamide / acrylate / methacrylic acid terpolymer, styrene / Maleic anhydride copolymer alkali salt,
Isobutylene / maleic anhydride copolymer alkali salt, water-soluble polymers such as polyacrylamide, sodium alginate, gelatin, casein, polyvinyl acetate, polyurethane, styrene / butadiene copolymer, polyacrylic acid, polyacrylic acid ester Latexes such as vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate, ethylene / vinyl acetate copolymer, and styrene / butadiene / acrylic copolymer can be used. In the thermosensitive coloring layer of the present invention, together with the leuco dye, the developer and the filler, auxiliary additives commonly used in this type of thermosensitive recording material, for example, a surfactant, a heat-fusible substance (or a lubricant) ) Etc. can be used in combination. In this case, examples of the heat-fusible substance include higher fatty acids or esters, amides, and metal salts thereof, various waxes, condensates of aromatic carboxylic acids and amines, benzoic acid phenyl esters, and higher linear glycols. , 3,4-epoxyhexahydrohydrophthalic acid, higher ketones, and other heat-fusible organic compounds having a melting point of about 50 to 200 ° C. The heat-sensitive recording material of the present invention can be prepared by a generally known method. For example, first, the leuco dye and the developer are separated at least separately, and a ball mill, an attritor and an aqueous solution of a water-soluble polymer such as polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, an alkali salt of a styrene-maleic anhydride copolymer, and starch are used. , Pulverized and dispersed by a dispersing machine such as a sand mill until the dispersed particle size becomes 1 to 3μ, and then blended into a prescribed formulation with a filler, a heat-fusible substance dispersion liquid, an antifoaming agent, etc., if necessary, to form a thermosensitive color. Prepare a layer coating solution. Further, the overcoat liquid is prepared by mixing or dispersing a binder, aluminum hydroxide and the like. Next, these coating liquids are sequentially coated and laminated on a support such as paper or synthetic paper to prepare the heat-sensitive recording material of the present invention. [Effect] The heat-sensitive recording material of the present invention comprises a specific amount of a water-soluble polymer and a water-proofing agent on the heat-sensitive coloring layer.
By providing an overcoat layer containing aluminum hydroxide and a binder in combination with a polyamide epichlorohydrin resin with a specific amount of adhesion, a reduction in color development sensitivity is small, and oil resistance, water peeling resistance and image reliability are reduced. It is high and has excellent head matching properties. EXAMPLES Next, the present invention will be described in more detail with reference to examples. The following parts and%
Are based on weight. Example 1 A mixture having the following composition was pulverized and dispersed by a ball mill and an attritor until the volume average diameter became about 1.5 μ to prepare a liquid [A] and a liquid [B]. [A] solution 20 parts by weight of 3- (N-cyclohexyl-N-methyl) amino-6-methyl-7-anilinofluoran 16 parts by weight of a 10% aqueous polyvinyl alcohol solution 64 parts by weight of water [B] solution 10 parts by weight of calcium carbonate Part 10% aqueous solution of polyvinyl alcohol 16 parts by weight Water 54 parts by weight Then, both were mixed and stirred at a weight ratio of [A] solution: [B] solution = 1: 4 to prepare a thermosensitive coloring layer coating solution. Further, a mixture having the following composition was dispersed in a sand mill to obtain an overcoat layer coating liquid. Aluminum hydroxide 20 parts by weight Itaconic acid-modified polyvinyl alcohol 10% aqueous solution of alkaline salt 40 parts by weight Zinc stearate 10 parts by weight Polyamide epichlorohydrin resin 10 parts by weight Water 20 parts by weight Next, these coating solutions were applied to a commercial high quality paper of 50 g / m ^2. dry coating weight of the heat-sensitive coloring layer Ioite is 3.0 g / m ^2, laminated by coating and drying each so as to be 3.0 g / m ² in the overcoat layer, a heat-sensitive recording material of the present invention did. Example 2 [C] Solution Bisphenol A 10 parts by weight Parabenzyldiphenyl 10 parts by weight Calcium carbonate 10 parts by weight 20% aqueous solution of polyvinyl alcohol 20 parts by weight Water 50 parts by weight is prepared in the same manner as the solution B of Example 1. Then, the two components were mixed and stirred at a weight ratio of [A] solution: [C] solution = 1: 4 to obtain a thermosensitive coloring layer coating solution, and a thermosensitive recording material of the present invention was prepared in the same manner as in Example 1. Comparative Examples 1 and 2 A heat-sensitive recording material of Comparative Example was prepared in the same manner as in Examples 1 and 2 except that the overcoat layer was not provided in Examples 1 and 2. Comparative Example 3 A heat-sensitive recording material of Comparative Example was prepared in the same manner as in Example 1 except that calcium carbonate was used instead of aluminum hydroxide in the overcoat layer of Example 1. Comparative Example 4 A heat-sensitive recording material of Comparative Example was prepared in the same manner as in Example 1 except that silica was used instead of aluminum hydroxide in the overcoat layer of Example 1. With respect to the above heat-sensitive recording material, the Bekk smoothness after leaving for 48 hours at room temperature was 700 to 700.
Tests were conducted for dynamic color development sensitivity, image browning, image whitening, oil resistance, water resistance, and sticking by calendering to 1000 seconds. Table 1 shows the results. (1) Dynamic coloring sensitivity: Head power 0.45 W / dot, one line recording time 20 ms / l, scanning line density 8 × 3.85, manufactured by Matsushita Electronic Components Co., Ltd. Pulse width of 0.8, 1.2, 1.6 under the condition of dots / mm
, 2.0 msec, and the print density was measured with a Macbeth densitometer RD-514. (2) brown rate of the image ... for samples measuring the dynamic color developing sensitivity (1), print density (and this D ₀₎ those 1.0-1.2 after standing for 15 days at room temperature Was measured (referred to as D), and the image brown ratio was determined as follows. (3) Image whitening: The same test as in (2) was performed, and the image was visually judged as follows. ：: Almost no white powder generated Δ: White powder was generated but no problem in practical use ×: White powder was generated and not practical (4) Oil resistance: (2) except that castor oil 0.5 g / m ² was adhered to the image An experiment was performed in the same manner as described above, and the following judgment was made. ：: Image brown ratio of less than 30% △: Image brown ratio of 30 to 50% ×: Image brown ratio of 50% or more (5) Water-peeling resistance: A print sample was immersed in water for 24 hours to conduct a test for the presence or absence of layer peeling. The evaluation was performed as follows. ○: No layer peeling ×: Layer peeling (6) Sticking: Using a printing device used for dynamic color sensitivity, changing the head power to 0.6 W / dot, the pulse width to 2.9 ms, and checking for sticking. A test was performed and the results were determined as follows. ○: No sticking ×: Sticking

Claims (1)

Claims: (1) In a thermosensitive recording material comprising a heat-sensitive coloring layer containing a leuco dye and a color developer provided on a support, and an overcoat layer provided thereon, ,
20-70% by weight of a binder using a polyamide epichlorohydrin resin as a water- soluble polymer and a water-proofing agent, and 5-45% by weight of aluminum hydroxide as a filler
And a dry adhesion amount of the overcoat layer of 1.0 to 6.0 g / m < ² >.