JP4779005B2 - Adhesive sheet for thermal recording with alcohol resistance for disinfection - Google Patents

Description

  The present invention relates to a heat-sensitive recording pressure-sensitive adhesive sheet, and more particularly to a heat-sensitive recording material having good color developability, no background fogging with a solvent, and excellent storage stability.

  Regarding the thermal recording method, many methods have been known for a long time. For example, Patent Documents 1, 2, and 3 disclose heat-sensitive recording materials using an electron-donating dye precursor and an electron-accepting compound. Such heat-sensitive recording materials are primary color development and are widely used for facsimiles, handy terminals, cash register papers and various printers due to their features such as easy hardware maintenance, and in recent years they are used in the field of recording paper such as measuring instruments. The number of cases is increasing.

In the POS system in the printer field, label printing can be performed at high speed due to the development of information processing technology and the performance of recorders. Label paper with high color development and high color development is desired. Opportunities for severe use in distribution management applications such as process management adhesive sheets and air baggage tags are also increasing. In the field of medical use, there is a demand for a pressure-sensitive adhesive sheet that has less color erasure and less background fogging with respect to disinfecting alcohol mainly composed of ethanol and / or isopropyl alcohol.
Japanese Examined Patent Publication No. 45-14039 Japanese Patent Publication No.43-4160 Japanese Patent Publication No. 2-8917

  An object of the present invention is to provide a thermal recording pressure-sensitive adhesive sheet that is excellent in high-speed recording properties and is less likely to cause discoloration and background fogging of a printing portion with respect to disinfecting alcohol mainly composed of ethanol and / or isopropyl alcohol. is there.

The above-described problem is that a heat-sensitive recording layer containing a colorless or light-colored leuco compound, a color developer and a sensitizer for coloring the leuco compound when heated is provided on the support, and an overcoat layer is formed on the heat-sensitive recording layer. In the heat-sensitive recording material provided with the above, in the heat-sensitive recording layer, 3-dibutylamino-6-methyl-7-anilinofluorane as the leuco compound and 4-hydroxy-4′-allyloxydiphenyl sulfone as the developer, It has 1,2-bis (3-methylphenoxy ) ethane as a sensitizer, and uses a carboxyl-modified polyvinyl alcohol as a resin component in the overcoat layer, which has alcohol resistance for disinfection. This is solved by a heat-sensitive recording pressure-sensitive adhesive sheet (hereinafter sometimes simply referred to as “heat-sensitive recording pressure-sensitive adhesive sheet”) .

  This heat-sensitive recording adhesive sheet has high color development sensitivity, excellent high-speed recording performance as compared with the past, and is used for medical disinfection alcohol, that is, disinfecting alcohol mainly composed of ethanol and / or isopropyl alcohol. On the other hand, it is possible to provide a heat-sensitive recording pressure-sensitive adhesive sheet that is less likely to cause color erasure and background fogging of the printing portion.

Next, the thermal recording material of the present invention will be described in detail.
In general, a heat-sensitive recording medium having good printing section storability is alcohol, and the printing section is less decolored. On the other hand, the background fog is large when alcohol is applied to a white paper section, and as a countermeasure, a thick overcoat layer is applied. However, if the overcoat layer is thickened, the color development sensitivity is lowered and the dot reproducibility is inferior in a high-speed printer.

  Therefore, it is desirable that the thickness of the overcoat layer is suppressed, and even if alcohol penetrates into the heat-sensitive recording layer, the printed portion is less decolored and the background portion is not fogged.

The addition amount of the leuco compound, the developer and the sensitizer is preferably 5 to 20% by mass of 3-dibutylamino-6-methyl-7-anilinofluorane in terms of solid content in the heat-sensitive recording layer. Hydroxy-4'-allyloxydiphenylsulfone is 1 to 8 parts by weight with respect to 1 part by weight of the leuco compound, and 1,2-bis (3-methylphenoxy ) ethane is 1 to 8 parts by weight with respect to 1 part by weight of the leuco compound. Is preferred.

  Moreover, it is more preferable to add various waterproofing agents for the purpose of making the carboxyl-modified polyvinyl alcohol in the resin in the overcoat layer water resistant.

  Examples of water-proofing agents include glyoxal, melamine resin, polyamide resin, polyethyleneimine resin, boric acid, zirconium chelating agent, isocyanate compound and the like.

  Next, conditions for using and producing typical heat-sensitive recording layers of the present invention will be described.

  The leuco compound / developer / sensitizer compound is generally pulverized to 2 μm or less with a water-soluble polymer aqueous solution such as polyvinyl alcohol using a ball mill, a sand mill or the like. The sensitizer may be added to either the leuco compound or the developer, or both, and pulverized at the same time, or in some cases, a eutectic material may be prepared in advance and dispersed.

  These dispersions are mixed after dispersion, and if necessary, pigments, surfactants, binders (adhesives), waxes, metal soaps, antioxidants, UV absorbers, etc. are added to make a coating solution for producing a heat-sensitive recording layer. .

  Examples of the pigment in the coating solution for producing the heat-sensitive recording layer include calcium carbonate, kaolin, silica, and aluminum hydroxide. The binder in the coating solution is polyvinyl alcohol, sulfonyl-modified polyvinyl alcohol, carboxyl-modified polyvinyl alcohol, silicic acid-modified polyvinyl alcohol, methyl cellulose, starches, carboxymethyl cellulose, hydroxyethyl cellulose, casein, styrene / butadiene copolymer emulsion, acrylic acid ester copolymer. It is at least one of polymer-based latex and polyurethane resin. The blending amount of the pigment and the binder is a total amount, and is 5 to 40% by mass based on the total solid content of the coating liquid.

  Examples of waxes that can be included in the coating liquid include natural waxes such as carnauba wax, and synthetic waxes such as paraffin wax and polyethylene wax. Examples of the metal soap that can be contained in the coating liquid include zinc stearate, calcium stearate, aluminum stearate, zinc oleate and the like.

  The method for forming the thermal recording layer and the overcoat layer is not particularly limited. For example, bar coating, air knife coating, die coating, Barry blade coating, pure blade coating, gravure coating, rod blade coating, short dwell coating, curtain coating , Etc.

  The overcoat layer on the thermosensitive recording layer contains carboxyl-modified polyvinyl alcohol as a resin component, but when adjustment of the viscosity of the overcoat coating liquid is necessary, polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, sulfonyl-modified polyvinyl alcohol, Silica-modified polyvinyl alcohol, methyl cellulose, starches, carboxymethyl cellulose, hydroxyethyl cellulose, casein and the like may be mixed in an amount of about 5 to 30% by mass based on the solid content of the carboxyl-modified polyvinyl alcohol.

  If necessary, a pigment such as calcium carbonate, kaolin, silica, aluminum hydroxide, a metal soap / wax, an ultraviolet absorber, a curing agent, and the like are added and mixed and stirred to prepare an overcoat coating solution.

The coating amount of the overcoat layer is 0.2 to 5 g / m ² , preferably 1.5 to 4 g / m ² . An overcoat coating solution is prepared using the above components, and the coating solution is applied onto the heat-sensitive recording layer and dried to obtain the desired overcoat layer.

In the heat-sensitive recording material of the present invention, an undercoat layer can be provided between the heat-sensitive recording layer and the support, if necessary, in order to obtain smoothness and heat insulation. The application amount of this undercoat layer is preferably 1 to 15 g / m ² , more preferably 4 to 12 g / m ² .

  The pigment used for the undercoat layer is generally calcined kaolin, but inorganic pigments such as calcium carbonate, talc, kaolin, zinc oxide, aluminum hydroxide, magnesium hydroxide, silica, alumina, styrene / acrylic resin, polyethylene resin Organic pigments such as polypropylene resin, polystyrene resin, and acrylic resin can be used. It is also effective to use inorganic / organic pigments having a larger number of pores, hollow particles, expanded particles, and air capsules in order to obtain further heat insulation.

As binders used for the undercoat layer, conventionally known polyvinyl alcohol, carboxyl-modified polyvinyl alcohol, sulfonyl-modified polyvinyl alcohol, silicic acid-modified polyvinyl alcohol, methyl cellulose, starches, carboxymethyl cellulose, hydroxyethyl cellulose, casein, styrene / butadiene copolymer emulsion, Examples include acrylate copolymer latex, polyurethane resin, vinyl acetate resin, and ethylene vinyl acetate resin.
Moreover, generally well-known water-proofing agent can be contained not only in the said heat-sensitive recording layer but in the undercoat layer as long as the effect of the invention is not impaired. Examples of the water-resistant agent include formalin, glyoxal, melamine resin, polyamide resin, polyethyleneimine resin and the like.

  Paper is generally used as the support, but a synthetic resin film such as polyethylene terephthalate or polypropylene, a laminate of synthetic resin such as polyethylene or polypropylene and paper, or a laminate may be used.

  In addition, it is of course possible to provide an anti-tacking protective layer, such as a release paper, a release film, etc., in order to prevent the adhesive applied to the back surface of the support from unintentionally adhering to non-objects. Various known techniques in the field of manufacturing a thermal recording material are added.

  Next, typical use conditions and production conditions of the present invention will be described.

Example:
EXAMPLES The present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. Further, unless otherwise specified, parts and% in Examples and Comparative Examples are parts by mass and% by mass, respectively.

(Formation of undercoat layer)
40% dispersion of calcined clay 45 parts by weight polyvinyl alcohol 15% aqueous solution 35 parts by weight water 20 parts by weight These components were mixed to prepare a coating solution for undercoat. This coating solution was applied and dried on fine paper so that the coating amount after drying was 8 g / m ² to form an undercoat layer.

(Preparation of A-1 liquid)
3-dibutylamino-6-methyl-7-anilinofluorane 10 parts by weight Polyvinyl alcohol 15% aqueous solution 12 parts by weight water 8 parts by weight These components were pulverized with a sand grinder until the average particle size became 0.6 µm. A-1 liquid was obtained.

(B-1 liquid preparation)
4-hydroxy-4'-allyloxydiphenylsulfone 10 parts by weight polyvinyl alcohol 15% aqueous solution 12 parts by weight water 8 parts by weight These components were pulverized with a sand grinder until the average particle size became 1 µm, and the solution B-1 was Obtained.

(Preparation of C-1 liquid)
1,2-bis (3-methylphenoxy ) ethane 10 parts by weight Polyvinyl alcohol 15% aqueous solution 12 parts by weight water 8 parts by weight These components were pulverized with a sand grinder until the average particle size became 1 μm, and the solution C-1 Got.

(D-1 liquid preparation)
Calcium carbonate (55% dispersion) 10 parts by weight water 12.5 parts by weight These components were dispersed with a disperser to obtain a D-1 solution.

(Formation of thermal recording layer)
Each composition of 10 parts by mass of A-1, 20 parts by mass of B-1, 20 parts by mass of C-1 liquid and 35 parts by mass of D-1 liquid was mixed and stirred, did. The obtained thermal recording layer coating solution was applied onto the undercoat layer so that the dry weight was 7 g / m ² and dried to form a thermal recording layer.

(Formation of overcoat layer)
Carboxyl-modified polyvinyl alcohol [trade name: KL-318, manufactured by Kuraray Co., Ltd.] (10% solution)
70 parts by weight calcium carbonate (40% dispersion) 8 parts by weight zinc stearate (30%) 2 parts by weight water 10 parts by weight
These components were mixed and stirred to obtain an overcoat coating solution.
The obtained overcoat coating liquid was applied onto the heat-sensitive recording layer and dried so as to have a dry weight of 3 g / m ^2, and then a surface smoothing treatment was performed with a super calendar to obtain a heat-sensitive recording sheet.

(Formation of adhesive layer)
An adhesive resin for strong recording was obtained by applying and drying an acrylic resin-based adhesive emulsion for strong adhesion on the back surface of the support opposite to the recording surface so that the coating amount after drying was 20 g / m ² .

In the overcoat layer formation of Example 1, carboxyl-modified polyvinyl alcohol [trade name: KL-318, manufactured by Kuraray Co., Ltd.] (10% solution)
70 parts by weight calcium carbonate (40% dispersion) 4 parts by weight zinc stearate (30%) 2 parts by weight polyamide epichlorohydrin resin [trade name: WS500C, manufactured by Seiko PMC] (30% liquid)
10 parts by mass A pressure-sensitive adhesive sheet for thermal recording was obtained in the same manner as in Example 1 except that these components were mixed and stirred to obtain an overcoat coating solution.

Comparative Example 1:
In the formation of the thermosensitive recording layer of Example 1, 10 parts by mass of 3-dibutylamino-6-methyl-7-anilinofluorane was changed to 10 parts by mass of 3-diethylamino-6-methyl-7-anilinofluorane. Except for the above, a pressure-sensitive adhesive sheet for thermal recording was obtained in the same manner as in Example 1.

Comparative Example 2:
The same as Example 1 except that 10 parts by mass of 4-hydroxy-4′-allyloxydiphenyl sulfone was changed to 10 parts by mass of 4-hydroxy-4′-isopropoxydiphenyl sulfone in the formation of the thermosensitive recording layer of Example 1. Thus, an adhesive sheet for thermal recording was obtained.

Comparative Example 3:
The same procedure as in Example 1 was conducted except that 10 parts by mass of 1,2-bis (3-methylphenoxy ) ethane was changed to 10 parts by mass of di (p-methylbenzyl) oxalate in the formation of the thermosensitive recording layer of Example 1. Thus, an adhesive sheet for thermal recording was obtained.

Comparative Example 4:
A pressure-sensitive adhesive sheet for thermal recording was obtained in the same manner as in Example 1 except that 70 parts by mass of carboxyl-modified polyvinyl alcohol was changed to 70 parts by mass of acetoacetyl-modified polyvinyl alcohol in the formation of the overcoat layer of Example 1.

The following evaluations were performed on the heat-sensitive recording adhesive sheets obtained in the above Examples and Comparative Examples, and the results are shown in Table 1.
(1) Color development test Thermal evaluation machine TH-PMH2 (Okura Electric Co., Ltd.) was used for evaluation. Printing was performed under the following conditions.
Line speed 2.0ms / line
Printing energy 0.17mj / dot
The density of the recording part was measured with a Macbeth RD-918 reflection densitometer.
(2) Alcohol fading test of printed part 3CC of ethanol 70% solution or isopropyl alcohol 70% solution was respectively picked up on the recording part of the sheet obtained by the color development test, wiped off after 3 minutes, and after the treatment after dripping The density was measured with a Macbeth RD-918 reflection densitometer.
(3) Alcohol discoloration test of the white paper part 3CC of ethanol 70% solution or isopropyl alcohol 70% liquid was respectively picked on the white paper part of the obtained thermal recording pressure-sensitive adhesive sheet, wiped off after 3 minutes, and treated after dripping. The density was measured with a Macbeth RD-918 reflection densitometer.

  As shown in Table 1, the thermal recording pressure-sensitive adhesive sheets obtained in the examples are excellent in high-speed printing, and the decoloring of the printed part and background fogging occur with respect to disinfecting alcohol mainly composed of ethanol or isopropyl alcohol. It was difficult.

Claims (1)

A heat-sensitive recording layer containing a colorless or light-colored leuco compound, a color developer and a sensitizer for coloring the leuco compound when heated on a support, and an overcoat layer provided on the heat-sensitive recording layer In the recording material, 3-dibutylamino-6-methyl-7-anilinofluorane as a leuco compound, 4-hydroxy-4'-allyloxydiphenyl sulfone as a developer, and a sensitizer in the heat-sensitive recording layer containing 1,2-bis (3-methylphenoxy) ethane as, and is characterized by using a carboxy-modified polyvinyl alcohol as the resin component in the overcoat layer, the thermosensitive recording adhesive with digestion poison for alcoholic Sheet.