JP3358007B2 - Thermal recording material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a heat-sensitive recording material utilizing a color-forming reaction between a leuco dye and a color developer.

[0002]

2. Description of the Related Art In recent years, a recording material provided with a heat-sensitive coloring layer capable of causing a chemical or physical change by heat energy to form a recorded image on a support such as paper, synthetic paper, plastic film, etc. is simply heated. Printers, facsimile machines, etc., because they have the advantages of being able to obtain recordings alone, not requiring complicated development and fixing processes, generating no noise at the time of recording, and being relatively easy and inexpensive to manufacture.
It is widely used in various information devices such as recorders and measuring instruments. Many of these thermosensitive recording materials have been put to practical use, and among them, triphenylmethane-based, fluoran-based, spiropyran-based colorless or slightly pale leuco bodies, and the leuco bodies A heat-sensitive recording material containing a heat-sensitive coloring layer containing, as a color-forming component, an acidic substance which causes a leuco body to react with heat to form a leuco body, for example, an organic acid or a phenolic acidic substance, has a high coloring density of a recorded image obtained. Therefore, it is used as a particularly useful recording material. In addition, application to vouchers for automatic ticket vending machines, such as commuter passes using the above-mentioned leuco body and acidic substances, bar code paper in POS systems, display labels for products, etc., is also being promoted, but it is still satisfactory. No results were obtained. For example, in the case of the above-mentioned note paper, after printing with a thermal line printer, it is put in a transparent vinyl case (periodical case) or the like, and in the case of barcode paper or a display label, after printing with a label printer, the product is packed. For example, it is used in a state where the above-mentioned film or the like is in contact with the surface of the heat-sensitive coloring layer such that the film is stuck on or under a wrap film or the like made of polyvinyl chloride or the like. However, these films contain plasticizers such as dioctyl phthalate and dioctyl adipate in order to improve the plasticity, and these plasticizers can cause the image areas thermally printed by the printer to lose color. There are drawbacks. Further, the heat-sensitive recording material has disadvantages such as coloring of an unprinted portion (background portion) when exposed to an alcohol-based chemical or the like, and decoloration of a printed portion (image portion) due to contact with water.

In order to remedy such a drawback, an undercoat layer and a back coat layer are provided on the support and the thermosensitive coloring layer to prevent the plasticizer from entering the overcoat layer or the back surface from the thermosensitive coloring. It is often provided between or on the back surface of the support. These layers contain a resin as a main component, and a water-soluble resin such as polyvinyl alcohol is mainly used. These have good film-forming properties and are excellent in plasticizer properties, but have poor water resistance, take a long time to dry when applied (coating drying property), and take time and labor for drying and the like. There are disadvantages. Further, when the undercoat layer and the overcoat layer on the back surface of the support are simultaneously applied and the heat-sensitive material after application is wound up in a roll, there is a disadvantage that the heat-sensitive recording materials stick together (blocking). In some cases, printing is provided on the surface of the heat-sensitive recording material for use, but the printability (ink adhesion) is still insufficient. On the other hand, the emulsion resin is excellent in coating drying property, water resistance, blocking and the like, but is inferior in plasticizer resistance. In addition, even if the plasticizer resistance is excellent, the film formability is poor, and the amount of filler is required to improve the matching property of the thermal head of the label printer (scrap adheres to the thermal head during printing, causing print blurring). At present, there is no room for plasticizer properties, such as a decrease in plasticizer resistance, and there are still problems in quality.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been made in view of such circumstances, and its object is to provide a plasticizer-resistant,
There is a need to provide a heat-sensitive recording material excellent in printability, coating drying property and blocking resistance.

[0005]

According to the present invention, there is provided a thermosensitive recording apparatus comprising: a heat-sensitive coloring layer which is colored by heat provided on a support; and an overcoat layer comprising a resin as a main component on the heat-sensitive coloring layer. In the material, a core / shell type emulsion resin in which a core is a copolymer of acrylamide or methacrylamide and a vinyl compound copolymerizable therewith and a shell is made of a polyvinyl alcohol-based polymer is used as the resin. A recording material is provided. Further, according to the present invention, a heat-sensitive coloring layer that is colored by heat is provided on the support,
An overcoat layer containing a resin as a main component on the thermosensitive coloring layer
In addition, the undercoat layer containing a resin as a main component between the support and the thermosensitive coloring layer, the backcoat layer containing a resin as a main component on the back of the support, in a thermosensitive recording material provided with at least one or more, There is provided a heat-sensitive recording material characterized by using the above resin as the resin.

In the present invention, by using a core / shell type emulsion resin in which the core is a copolymer of acrylamide or methacrylamide and a vinyl compound copolymerizable therewith, and the shell is a polyvinyl alcohol-based polymer, A heat-sensitive recording material which is excellent in plasticizer properties, coating drying properties and printability and does not cause blocking can be obtained.

[0007] The resin used in the present invention comprises a double-layered emulsion of a portion called a core and a shell surrounding the core, and the core portion is copolymerized with acrylamide or methacrylamide. It is composed of a copolymer with possible vinyl, and the shell part is composed of polyvinyl alcohol resin. The use of carboxy-modified PVA for the shell further improves the plasticizer properties. This is thought to be due to the fact that the introduction of polyvinyl alcohol into the shell improves the film forming property, which is originally a drawback of the emulsion system, and thus improves the plasticizer resistance. It is considered that acrylic amide contributed to the improvement of printability. Further, by covering the copolymer with PVA, the acrylamide-based copolymer which is weak to heat is protected.

[0008] The resin used in the present invention is a core / shell type resin, which is different from ordinary copolymers and mixtures. When formed, the resin has a three-layer structure of a shell part / core part / shell part. And the properties of each resin can be utilized uniformly. Another characteristic is that since it is an emulsion type, the drying speed after coating is high. The overcoat layer will be described. The resin used for the overcoat is the resin of the present invention. If necessary, auxiliary resins used in this type of heat-sensitive recording material, such as fillers, surfactants, heat-fusible substances (or lubricants) ) Etc. can be used in combination. In this case, as the filler, for example, other than inorganic fine powder such as calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, surface-treated calcium and silica, etc. , Urea-formalin resin, styrene / methacrylic acid copolymer, polystyrene resin, and other organic fine powders. Examples of the heat-fusible substance include higher fatty acids or esters, amides or metal salts thereof. In addition, various waxes, condensates of aromatic carboxylic acids and amines, phenyl benzoate, higher linear glycols, dialkyl 3,4-epoxy-hexahydrophthalate, higher ketones, and other heat-fusible organic compounds Compounds having a melting point of about 50 to 200 ° C, such as compounds, may be mentioned.

In order to improve the water resistance, if necessary, a water-resistant agent such as a polyamide resin, a melamine resin, or glyoxal, or a head-matching property may be used.
Fillers used in heat-sensitive recording materials such as calcium carbonate, clay and urea formalin resin, and lubricants such as zinc stearate and polyethylene wax can be further contained.

[0010] Resins that can be used in combination include completely saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, modified polyvinyl alcohol (eg, methylol-modified, alkoxy-modified, silica-modified, etc.) starch and its derivatives, methoxycellulose, Hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose, cellulose derivatives such as ethyl cellulose,
Sodium polyacrylate, polyvinylpyrrolidone, acrylamide / acrylate copolymer, acrylamide / acrylate / methacrylic acid terpolymer, styrene / maleic anhydride copolymer acrylic salt, polyacrylamide, alginic acid In addition to water-soluble polymers such as soda, gelatin and casein, polyvinyl acetate, polyurethane, styrene / butadiene copolymer, polyacrylic acid, polyacrylate, vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate, ethylene Latexes such as styrene / vinyl acetate copolymers and styrene / butadiene / acrylic copolymers can be used.

The leuco dye used in the heat-sensitive recording layer of the present invention may be used alone or as a mixture of two or more kinds. As such a leuco dye, those applied to this kind of heat-sensitive material may be arbitrarily applied. For example, leuco compounds of dyes such as triphenylmethane type, fluoran type, phenothiazine type, auramine type, spiropyran type and indolinophthalide type are 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-cyclohexylamino-6-chlorofluoran, 3-dimethylamino-5,7 -Dimethylfluoran, 3-diethylamino-7-chlorofluoran, 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)-
Lactam 9- (o-chloroanilino) xanthylbenzoate, 3-diethylamino-6-methyl-7- (m-trichloromethylanilino) fluoran, 3-diethylamino-7- (o-chloroanilino) fluoran, 3-di- n-butylamino-7- (o-chloroanilino) fluoran, 3-N-methyl-N, 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-benzoindolino-spiropyran, 6 '
-Bromo-3'-methoxy-benzoindolino-spiropyran, 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-
(N-ethyl-N-tetrahydrofurfuryl) amino-
6-methyl-7-anilinofluoran, 3-N-ethyl-N- (2-ethoxypropyl) amino-6-methyl-
7-anilinofluoran, 3-N-methyl-N-isobutyl-6-methyl-7-anilinofluoran 3-morpholino-7- (N-propyl-trifluoromethylanilino) fluoran, 3-pyrrolidino- 7-m-
Trifluoromethylanilinofluoran, 3-diethylamino-5-chloro-7- (N-benzyl-trifluoromethylanilino) fluoran, 3-pyrrolidino-7-
(Di-p-chlorophenyl) methylaminofluoran, 3
-Diethylamino-5-chloro-7- (α-phenylethylamino) 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-methyl-N-isopropylamino) -6-methyl-7-anilinofluoran, 3-di-n-butylamino-6-methyl-7-anilino Fluorane, 3,6-bis (dimethylamino) fluorenespiro (9,3 ')-6'-dimethylaminophthalide, 3- (N-benzyl-N-cyclohexylamino) -5,6-benzo-7- α-naphthylamino-4′-bromofluoran, 3-diethylamino-
6-chloro-7-anilinofluoran, 3-diethylamino-6-methyl-7-mesitidino-4 ′, 5′-benzofluoran, 3-N-methyl-N-isopropyl-6
Methyl-7-anilinofluoran, 3-N-ethyl-N
-Isoamyl-6-methyl-7-anilinofluoran,
3-diethylamino-6-methyl-7- (2 ', 4'-dimethylanilino) fluoran and the like.

As the color developer used in the heat-sensitive recording layer of the present invention, various compounds having an electron-accepting property or a oxidizing agent which develop the color of the leuco dye upon contact are applied. Such materials are conventionally known, and specific examples thereof include the following.

4,4'-isopropylidene diphenol, 4,4'-isopropylidenebis (o-methylphenol), 4,4'-secondarybutylidenebisphenol 4,4'-isopropylidenebis (2-tertiary) Butylphenol), zinc p-nitrobenzoate, 1,3,
5-tris (4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanuric acid, 2,2
-(3,4'-dihydroxydiphenyl) propane, bis (4-hydroxy-3-methylphenyl) sulfide,
4- {β- (p-methoxyphenoxy) ethoxy} salicylic acid, 1,7-bis (4-hydroxyphenylthio)
-3,5-dioxaheptane, 1,5-bis (4-hydroxyphenylthio) -5-oxapentane, monobenzyl phthalate monocalcium salt, 4,4′-cyclohexylidene diphenol, 4,4 ′ -Isopropylidenebis (2-chlorophenol), 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 4,4'-butylidenebis (6-tert-butyl-2-methyl) phenol, 1, 1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, 4,4 ′ -Thiobis (6-tert-butyl-2
-Methyl) phenol, 4,4'-diphenolsulfone, 4-isopropoxy-4'-hydroxydiphenylsulfone, 4-benzyloxy-4'-hydroxydiphenylsulfone, 4,4'-diphenolsulfoxide,
Isopropyl P-hydroxybenzoate, benzyl P-hydroxybenzoate, benzyl protocatechuate, stearyl gallate, lauryl gallate, octyl gallate,
1,3-bis (4-hydroxyphenylthio) -propane, N, N′-diphenylthiourea, N, N′-di (m
-Chlorophenyl) thiourea, salicylanilide, methyl bis- (4-hydroxyphenyl) acetate, bis- (4
-Hydroxyphenyl) benzyl acetate, 1,3-bis (4-hydroxycumyl) benzene, 1,4-bis (4
-Hydroxycumyl) benzene, 2,4'-diphenolsulfone, 2,2'-diallyl-4,4'-diphenolsulfone, 3,4-dihydroxyphenyl-4'-methyldiphenylsulfone, 1-acetyloxy Zinc-2-naphthoate, zinc 2-acetyloxy-1-naphthoate, zinc 2-acetyloxy-3-naphthoate, α, α
-Bis (4-hydroxyphenyl) -α-methyltoluene, an antipyrine complex of zinc thiocyanate, tetrabromobisphenol A, tetrabromobisphenol S,
4,4′-thiobis (2-methylphenol), 4,4 ′
-Thiobis (2-chlorophenol) and the like.

To produce the heat-sensitive recording material of the present invention,
When the leuco dye and the developer are bound and supported on the support, various conventional binders can be appropriately used, and specific examples thereof include the following.

Polyvinyl alcohol, starch and derivatives thereof, cellulose derivatives such as hydroxymethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, ethylcellulose, etc., sodium polyacrylate, polyvinylpyrrolidone, acrylamide / acrylate copolymer, acrylamide /
Water-soluble polymers such as acrylate / methacrylic acid terpolymer, styrene / maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, casein, etc. In addition, polyvinyl acetate, polyurethane, polyacrylic acid, polyacrylate, vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate, emulsion of ethylene / vinyl acetate copolymer, styrene / butadiene copolymer, styrene / butadiene / Latexes such as acrylic copolymers.

Further, in the heat-sensitive recording layer of the present invention, together with the leuco dye and the developer, if necessary, auxiliary additives commonly used in this type of heat-sensitive recording material, for example, fillers, heat-fusible materials, Substances, surfactants and the like can be used in combination. In this case, as the filler, for example,
Calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay,
In addition to inorganic fine powders such as talc and surface-treated calcium and silica, organic fine powders such as urea-formalin resin, styrene / methacrylic acid copolymer, and polystyrene resin can be used. Examples of the active substance include higher fatty acids or esters, amides or metal salts thereof, various waxes, condensates of aromatic carboxylic acids and amines, phenyl benzoate, higher linear glycols, 3,4- Dialkyl epoxy-hexahydrophthalate, higher ketones, p-benzylbiphenyl, other heat-fusible organic compounds, and the like having a melting point of about 50 to 200 ° C can be mentioned.

Also, an overcoat layer as a binder,
The resins, fillers, surfactants, crosslinking agents, lubricants, and other auxiliaries described for the thermosensitive coloring layer can be used in combination. Also,
The resin used for the undercoat layer and the backcoat layer is the resin of the present invention, and the filler described above for the overcoat layer, the addition of a surfactant, a crosslinking agent or an auxiliary agent, or the resin described for the overcoat layer Can also be used together.

[0019]

The present invention will be described in more detail with reference to the following examples. <Formation of Undercoat Layer and Backcoat Layer> Liquid A Silicon oxide powder 20 parts Water 60 parts Polyvinyl alcohol 10% aqueous solution 20 parts The above Liquid A is dispersed by a sand mill and adjusted until the average particle diameter becomes 2 μm or less. Liquid B (* 1) Liquid A x part (* 2) (* 3) Resin liquid 10% 40 parts Water 100-x part Liquid B had a dry adhesion amount of 3.5 on the support or on the back of the support.
g / m ² and dried to obtain an undercoat layer or a backcoat layer. * 1, * 2, and * 3 refer to Tables 1 and 2. <Formation of thermosensitive coloring layer> Liquid C 3- (N-cyclohexyl-N-methyl) amino 20 parts -6-methyl-7-anilinofluoran 10% aqueous solution of polyvinyl alcohol 20 parts Water 60 parts Liquid D 4-hydroxyphenyl -4'-Isopropoxy 10 parts Phenyl sulfone Calcium carbonate 10 parts Stearic acid amide 5 parts Polyvinyl alcohol 10% aqueous solution 20 parts Water 55 parts C solution and D solution are each dispersed by a sand mill so that the average particle diameter becomes 2μ or less. I do. Solution A and Solution B were mixed and stirred at a weight ratio of 1: 6 to obtain a thermosensitive coloring solution, and the amount of dye attached was 0.5 g.
/ M ² and dried to obtain a thermosensitive coloring layer. <Formation of overcoat layer> Liquid E Liquid A y part (* 4) Resin liquid (* 5) 10% 40 parts Zinc stearate 2 parts Water 100-y part Aridine cross-linking agent 10% solution 12 parts Heat sensitive liquid E An overcoat layer is formed by coating and drying on the coloring layer so that the dry adhesion amount is 3.5 g / m ² . The completed sample is placed on a super calendar (40Kg
(Calender pressure) twice. * 4 and * 5 refer to Tables 1 and 2. (Below)

[0020]

[Table 1]

[0021]

[Table 2] ━━━━━┻━━━┛

The following evaluations were performed on the heat-sensitive recording materials obtained in Examples and Comparative Examples. Table 3 shows the results.・ Plasticizer resistance test The sample was printed with a heat block at 150 ° C, the polymer wrap was pressed against the surface of the heat-sensitive recording material, left at 40 ° C overnight, and the density of the printed portion was measured with a Macbeth reflection densitometer (RD- 9
Measure in 14). -Printability The surface of the heat-sensitive recording material is printed with G-mar Blu on a printing machine.
e-Ink printing, Macbeth reflection densitometer (RD-9
The density of blue is measured using the yellow filter of 14).・ Backside plasticizer Print with a 150 ° C heat block, press the polymer wrap from the back of the thermosensitive recording material, leave at 40 ° C overnight, and measure the density of the printed area with a Macbeth reflection densitometer (RD-914). I do. -Coating drying property The drying state after standing for 2 minutes after coating is judged visually and by hand. ：: Dry, Δ: Slightly wet, ×: Wet ・ Blocking property After application, conditioned at 23 ° C., 50% for 30 minutes, sample 10
After stacking and sealing with polyethylene film, weight 5K
g was placed and left at 40 ° C. for 24 hours to check for blocking. ○: None, △: Slightly available, ×: Available (Margin)

[0023]

[Table 3] As described above, the heat-sensitive recording material of the present invention has plasticizer properties, printability,
It turns out that it is excellent in coating drying property and blocking.

[0024]

The present invention has the above-mentioned structure,
A heat-sensitive recording material which is excellent in plasticizer properties, printability and coating / drying properties and has little blocking can be obtained.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP 5-318926 (JP, A) JP 5-201136 (JP, A) JP 5-69665 (JP, A) JP 6 32056 (JP, A) JP-A-6-227124 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41M 5/28-5/34

Claims (2)

(57) [Claims] 1. A thermosensitive recording material comprising: a heat-sensitive coloring layer provided by heat on a support; and an overcoat layer comprising a resin as a main component on the heat-sensitive coloring layer, wherein the resin has a core of acrylamide or methacrylic. A heat-sensitive recording material characterized by using a core / shell type emulsion resin comprising a copolymer of an amide and a vinyl compound copolymerizable therewith, and a shell made of a polyvinyl alcohol-based polymer. 2. A heat-sensitive coloring layer which is colored by heat is provided on a support, and an overcoat mainly composed of a resin is provided on the heat-sensitive coloring layer.
Heat- sensitive recording material comprising a support layer and a resin-based undercoat layer between the support and the heat-sensitive coloring layer, and a backcoat layer comprising a resin as the main component on the back of the support. In claim 1, the resin as the resin
A heat-sensitive recording material characterized by using the following resin.