JPH0380438B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heat-sensitive recording paper useful for recording using a heat-sensitive color recording method. More specifically, the present invention relates to a heat-sensitive recording paper that is useful for high-definition, high-sensitivity, high-gradation, and high-preservability recording using a heat-sensitive color recording method, and is highly resistant to penetration by oils, fats, plasticizers, etc. It is something.

[Conventional technology]

Recently, advances in electronic graphics technology have been remarkable, and illustrations and analyzes using cathode ray tube displays,
Testing, diagnosis, etc. are becoming widely used. In particular, in order to record high-quality images using high-definition cathode ray tubes, it was previously necessary to use the dry silver method (Japanese Patent Publication No. 4924/1973). Although this method can provide high-quality recording, it has problems such as requiring dark box operation and high recording cost.

If conventional thermal recording paper is used to record cathode ray tube images, recording costs will be significantly reduced.
Although this method has the advantage of simplifying the recording operation, it has the disadvantages of insufficient recording quality and low storage stability.

In addition, in recent years, methods have been developed in which barcodes are attached to labels, cards, tags, slips, etc. and linked to computers for inventory management and business management. If conventional thermal recording paper is used in this method,
It has been recognized that barcodes have low image quality and low reading rates.

Furthermore, when conventional thermal recording paper comes into contact with oil-based substances such as oils and fats and plasticizers, substances containing these, or the surfaces of machines and equipment to which these substances have adhered, the oils and oil-based substances penetrate and the prints disappear. Problems are also acknowledged.

No means have yet been known to solve the problems of conventional thermal recording paper as described above.

[Problem that the invention seeks to solve]

The present invention aims to solve the problems of conventional thermal recording paper, such as unsatisfactory recording image quality, insufficient storage stability, and penetration of oils and oily substances.

[Means and actions for solving problems]

The thermosensitive recording paper of the present invention comprises a support, a thermosensitive coloring layer formed on one surface of the support and containing a colorless or light-colored leuco dye and an acidic color developing substance as coloring components; A protective printing layer is formed on the coloring layer and includes a water-soluble polymeric substance, a water-resistant agent for the water-soluble polymeric substance, and a white pigment, and the support is a base paper and a protective printing layer. , a white pigment-kneaded polyolefin resin layer formed between one surface of the base paper and the heat-sensitive coloring layer, and a matt-treated polyolefin resin layer formed on the opposite surface of the base paper. It is characterized by consisting of layers.

Further, another thermosensitive recording paper of the present invention includes: a support; a thermosensitive coloring layer formed on one surface of the support and containing a colorless or light-colored leuco dye and an acidic color developing substance as coloring components; Further, a protective printing layer is formed on the heat-sensitive coloring layer and includes a water-soluble polymeric substance, a water-resistant agent for the water-soluble polymeric substance, and a white pigment, and the support is It is characterized by being made of white pigment-kneaded polyolefin resin synthetic paper.

The structure of the thermal recording paper of the present invention will be explained with reference to the accompanying drawings.

In the heat-sensitive recording paper of the embodiment shown in FIG. A matted polyolefin resin layer 3 is formed and bonded to the surface of the substrate.

A thermosensitive coloring layer 4 is formed and bonded on the surface of the white pigment-kneaded polyolefin resin layer 2 of this support 6, and a protective/printing layer 5 is further formed and bonded on the surface. The thermosensitive coloring layer 4 and the protective/printing layer 5 constitute a thermosensitive coloring recording layer 7.

In the heat-sensitive recording paper of the embodiment shown in FIG. 2, the support 6a is made of white pigment-kneaded polyolefin resin synthetic paper. This support 6
On one side of a, a thermosensitive coloring layer 4 is provided in the same manner as described above,
Further, a thermosensitive color recording layer 7 consisting of a protective/printing layer 5 is formed and bonded on the surface thereof.

As the synthetic paper for the support 6a, for example, the following can be used.

(1) Calcium carbonate, clay, polypropylene,
An opaque sheet (UK) that contains an inorganic filler such as talc or a resin filler such as polyamide and extrudes the resulting sheet, which is stretched in uniaxial or biaxial directions. Patent No. 1360240, No. 1384556, No.
1470372).

(2) Vinyl acetate/vinyl chloride copolymer with inorganic fillers such as calcium carbonate, titanium oxide, and clay dispersed on the surface of polypropylene film;
Styrene/butyl acrylate copolymer, vinyl acetate/ethyl acrylate copolymer, ethylene/
An acrylic acid copolymer based resin emulsion is applied and dried to form a coating film on the surface of the film.

(3) Polypropylene or as required
A film formed by extruding a mixture containing 0.5 to 15% by weight of an inorganic filler and/or an incompatible resin filler, and the surface of which is sandblasted.

(4) A film in which the surface of the formed polypropylene film is treated with a good solvent for the film material, and then the surface is washed with hot water.

(5) A film in which an extruded polypropylene film is brought into contact with an embossing roll while it is still in a softened state, and then cooled to transfer an embossed pattern.

(6) A film made of extruded ethylene/propylene block copolymer or a stretched film thereof.

Examples of commercially available synthetic papers include Yupo FP (trade name) manufactured by Oji Yuka Synthetic Paper. This is polypropylene with an inorganic filler of 20~
It is a polypropylene synthetic paper with 45% by weight and stretched, which has open voids on the surface and pores inside.It has mechanical strength due to stretching, and flexibility due to the thixotropic property of the inorganic filler. Therefore, it is suitable as a support. The base paper used for the support is not particularly limited, but high-quality paper and cardboard are generally used. The thickness, stiffness, etc. of the base paper depend on the manner in which the thermal note is used, i.e., the label,
It is determined whether it is used for a tag or a card. The most important requirement for the base paper is that although the pigment-mixed polyolefin resin is laminated thereon, its surface flatness depends on the base paper's formation, surface properties, and flatness. It has good surface properties.

The polyolefin resin used in the white pigment-kneaded polyolefin resin layer of the support can be selected from polyethylene, polypropylene, polybutene, polypentene, copolymers thereof, and mixtures thereof. In addition, white pigments are
Traditionally used as white pigments for polyolefin resins, such as titanium dioxide, zinc sulfide, zinc oxide, calcium sulfate, calcium sulfite, barium sulfate, clay, calcined clay, talc, kaolin, calcium carbonate, white carbon, calcium silicate, etc. You can choose from the ones listed.
At this time, the white pigment has high whiteness,
It is preferable that the material satisfies requirements such as being able to be used in a melt extrusion laminator and not impairing the flatness of the resulting resin layer or the adhesion between the base paper and the resin layer. The size of this white pigment particle is
It is preferably 10 μm or less.

Generally, the content of the white pigment in the white pigment-kneaded polyolefin resin layer is preferably in the range of 5% to 20% (by weight).

The white pigment-kneaded polyolefin resin layer formed and bound on the base paper is formed using a melt extrusion laminator, and its surface has high flatness and high whiteness. A white pigment-kneaded polyolefin resin layer having such high flatness and high whiteness naturally makes the heat-sensitive color forming layer-holding surface of the support highly flat and high whiteness. A thermosensitive coloring layer formed on a surface having a high resolution can form an image with excellent high definition (high resolution), high sensitivity, and high gradation.

In the thermal recording paper of the present invention (FIG. 1), a matted polyolefin resin layer is formed and bonded on the opposite side (back side) of the base paper. The matting process of the polyolefin resin layer is performed by pressing a cooling roll whose surface has been matted in a desired pattern onto the surface of the polyolefin resin layer when extrusion laminating the polyolefin resin to the base paper. This is accomplished by embossing the matting pattern of the chill roll onto the resin surface.

The matted polyolefin resin layer can prevent the support from curling, and also enables printing and writing on the back side of the support, making it convenient to make necessary records.

The white pigment-kneaded polyolefin resin layer and matte polyolefin resin layer formed (laminated) on the base paper as described above allow oil and/or oil-soluble substances such as plasticizers to penetrate into the heat-sensitive recording layer. This is effective in preventing this and improving the stability of recorded images.

The support of the heat-sensitive recording paper of the embodiment shown in FIG. 2 is made of a white pigment-kneaded polyolefin resin synthetic paper. The white pigment and polyolefin resin used in this synthetic paper can be selected from those used in the above-mentioned white pigment-kneaded polyolefin resin layer. The content of white pigment in the synthetic paper is preferably 5% to 50% (by weight), more preferably 30% to 50% (by weight).

In the synthetic paper, the white pigment may be distributed only on both surface layers of the synthetic paper.

One side of the synthetic paper preferably has high flatness and high whiteness, and the opposite side may be matted to provide printing and writing properties.

This support made of synthetic paper has high flatness and whiteness, and is effective in preventing oils and fats and oil-soluble substances from penetrating into the heat-sensitive recording layer.

In the thermosensitive recording paper of the present invention, the thermosensitive coloring layer formed on the support contains a colorless or light-colored leuco dye and an acidic color developing substance as coloring components, and the thermosensitive coloring layer is formed on a support according to a predetermined image. , which, when heated, forms a colored image.

Leuco dyes (electron-donating colorless (light-colored) dyes are
Before heat-sensitive treatment, it is a colorless or light-colored organic compound, and upon heat-sensitive treatment, it reacts with an acidic color developing substance to develop color. Examples of such leuco dyes are as follows.

Crystal violet lactone, malachite green lactone, 3,3-bis(valadimethylaminophenyl)4,5,6,7tetra-rolfthalide, benzo-βnaphthospiropyran, 3-methyl-di-βnaphthospiropyran, 1, 3,3-
Trimethyl-6'-chloro-8-methoxyindolinobezospiropyran, N-phenylrhodamylactam, 3-ethylamino-6-chlorofluoran, 3-morpholino-5,6-benzofluorane, 3-diethylamino -6-Methyl-7-chlorofluorane, 3-diethylamino-6,7-dimethylfluorane, 3-diethylamino 7,8-
Benzofluorane, 3-diethylamino-6-methoxyfluorane, 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino-7-anilinofluorane, 3-diethylamino-5,6-benzo-7-benzyl Aminofluorane, 3-piperidino-6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-
Anilinofluorane, 3-N ethyl tolylamino-6-methyl-7-anilinofluorane, 3-
Diethylamino-7-(N-3-trifluoromethylphenyl)aminofluorane.

The acidic color developing substance (electron-accepting compound) contained in the heat-sensitive coloring layer has the property of liquefying or vaporizing at room temperature or higher, preferably 70°C or higher, and reacting with the color-forming leuco dye to generate color. , including the following Phale-based compounds.

4,4'-isopropylidenediphenol, 4,
4'-isopropylidene bis(2-chlorophenol), 4,4'-isopropylidene bis(2-tert-butylphenol), 4,4'-sec-butyldendiphenol, 4,4'-cyclohexylidene diphenol, 4-phenylphenol, 4-hydroxydiphenoxide, methyl-4
-Hydroxybenzoate, phenyl-4-hydroxybenzoate, 4-hydroxyacetophenone, salicylic acid anilide, novolac type phenolic resin, halogenated novolac type phenolic resin, α-naphthol, β-naphthol, 2,2-
Bis-(4-hydroxyphenyl)-n-heptane, 4-4'-thiobis-(6-t-butyl-3-
methylphenol), 4-4'-butylidene bis-
(6-t-butyl-3-methylphenol), and 4-4'-dihydroxydiphenylsulfone.

Among these compounds, phenolic substances that generally have two or more hydroxyl groups in one molecule are
Particularly effective. Furthermore, benzoic acid esters such as butyl paraoxybenzoate and benzyl paraoxybenzoate can be used or used in combination.

In the heat-sensitive coloring layer, the leuco dye and the acidic color-developing substance are dispersed in a binder in the form of fine particles and bound together. In this case, it is desirable to disperse the dispersed particles using a dispersing machine such as a sand grinder until the particles are as small as possible, specifically, particles with a size of 5 μm or less. As a dispersion aid, a surfactant such as a dispersant or an antifoaming agent can be used as necessary.Also, in order to further prevent the coating material from adhering to a whitening agent or a thermal head, talc, clay, calcium carbonate, Fillers such as titanium oxide and starch can also be added. Antifoaming agents to suppress foaming during coating and surfactants to improve coating properties can also be added. Further, in order to improve color development, waxes can be pulverized or used in the form of an emulsion.

As the binder, natural polymers such as starch, synthetic polymers such as polyvinyl alcohol, etc. are used.

In the heat-sensitive recording paper of the present invention, a protective/printing layer is formed and bonded on the heat-sensitive coloring layer. This protective/printing layer protects the heat-sensitive coloring property, increases its storage stability, and improves the printability of the surface of the heat-sensitive recording paper. As such a protective/printing layer, those disclosed in, for example, JP-A-57-29491 and JP-A-60-46294 may be used.

As the polymeric substance forming the matrix of the protective/printing layer, one is used that has excellent film-forming performance and whose film is not dissolved by organic solvents, plasticizers, etc. In general, heat-sensitive recording paper cannot be exposed to high temperatures when drying the protective/printing layer due to its basic property of developing color due to heat, so it has sufficient film-forming performance even when dried at low temperatures. There must be. In addition, in order to minimize the decrease in print density due to the influence of the protective/printing layer, the amount of coating is small, and even if the thickness of the protective layer is thin, the required performance such as plasticizer resistance and solvent resistance can be met. It must be satisfactory. Examples of such polymer compounds include casein, starch,
Highly water-soluble materials such as various modified starches, polyvinyl alcohol, hydroxyethyl cellulose, gum arabic, polyvinylpyrrolidone, alkali salts of acrylic acid ester copolymers, alkali salts of isobutylene/maleic anhydride copolymers, acrylamide, acrylonitrile copolymers, etc. Molecular compounds can be used.

In addition, by curing these water-soluble polymer compounds,
Furthermore, in order to impart water resistance, compounds containing methylol groups such as dimethylolurea, dimethylolmethylene, dimethylolmelamine, dimethylolethylene, and polymethylolurea, glyoxal, polyaldehydes, epoxy compounds, etc. are combined as crosslinking agents. use.

Furthermore, to improve printability, talc,
Clay, calcium carbonate, titanium oxide, silica,
A combination of inorganic and/or organic pigment particles such as starch particles and polystyrene, and synthetic polymer emulsions such as styrene-butadiene, polyurethane, polyvinyl complex acid, polyester, polyacrylate, and polymethacrylate are used. , UV ink affinity and UV on the surface of recording paper
It is preferable to have ink absorbency and also to be able to compensate for shear strain caused by shrinkage when the UV ink is cured. Furthermore, to improve compatibility with heat-sensitive heads, fatty acids such as oleic acid, fatty acid metal salts such as zinc stearate, polyolefins such as paraffin wax, and other waxes and oils such as silicone oil and whale oil are added. It's okay.

In addition, antifoaming agents, dispersants, conductive agents,
Pigments, leveling agents, etc. may also be used.

As for the coating method, it is preferable to apply the coating liquid for both the heat-sensitive coloring layer and the protective/printing layer using a coater such as an air knife, bar, roll, or blade, and drying at a relatively low temperature.

If a surface smoothing treatment is performed using a supercalender or the like after coating the heat-sensitive coloring layer and/or after coating the protective/printing layer, good results can be given to the uniformity of the colored image.

〔Example〕

The invention will be further illustrated by the following examples.

Examples 1 and 2 and Comparative Example 1 In Example 1, RC paper (weight 225 g/m ² ) was used as a support. This RC paper is
On one side of the base paper, a layer of polyethylene resin containing 10% by weight of titanium dioxide is melt-extruded laminated with a weight of 30 g/ ^m2 , and on the opposite side of the base paper, a layer of polyethylene resin containing 10% by weight of titanium dioxide is laminated with a weight of 30 g/m
A 25 g/m ² matted polyethylene resin layer was melt extrusion laminated.

A coating material for forming a heat-sensitive coloring layer was prepared by separately preparing liquids A and B having the following compositions, and then uniformly mixing them.

Liquid A Ingredient Weight Crystal Violet 1.5 parts Polyvinyl alcohol aqueous solution (concentration 20%)
5.0〃Water 43.5〃Total 50.0〃 B liquid component weight Bisphenol A 6.0 parts Calcium carbonate 3.0〃 Stearic acid amide 1.0〃 Polyvinyl alcohol aqueous solution (concentration 20%)
10.0〃Water 30.0〃Total 50.0 parts After corona discharge treatment was performed on the white pigment-kneaded polyethylene resin layer of the above RC paper, the above mixed paint was applied thereto, dried at 60℃, and weighed
A thermosensitive coloring layer of 6.0 g/m ² was formed.

As a coating liquid for forming a protective/printing layer, a mixture having the following composition was dispersed using a Cowles dispersant.

Component weight Acetoacetylated polyvinyl alcohol (10% aqueous solution) 10.0 parts Kaolin aqueous dispersion (concentration 60% by weight) 0.5 Zinc stearate (30% aqueous dispersion) 0.5 Polyaldehyde' (30% aqueous solution) 3.0 parts Total: 14.0 This dispersion coating liquid was applied onto the heat-sensitive color forming layer and dried at 60°C to form a protective/printing layer having a weight of 3.0 g/m ² . In Example 2, the same operations as in Example 1 were performed. However, as a support, polypropylene synthetic paper containing 30% by weight of titanium dioxide (trademark: Yupo FPG, manufactured by Oji Yuka Synthetic Paper Co., Ltd., thickness 80 μm, weight 61.5 g/m ² ) was used instead of RC paper. there was.

In Comparative Example 1, the same operations as in Example 1 were performed. However, instead of RC paper, high-quality paper with a basis weight of 64 g/m ² is used, and after forming a heat-sensitive coloring layer and a protective printing layer on one side, it is calendered, and the surface smoothness is 250 seconds. I made it so that

Each of the thermal recording papers obtained in Examples 1 and 2 and Comparative Example 1 was colored peta black using a facsimile machine (Copix7100, trademark, manufactured by Toshiba Corporation), and the color density of the resulting colored surface was measured using a Masbeth densitometer. (RD-514, manufactured by Masbeth Instrument Corporation), the following color density was obtained.

Color density (solid black) Example 1 1.20 Comparative Example 1 1.20 Example 2 1.25 Next, in order to measure the image quality of the recorded images of the three parties, a bar coat printing tester (SYMBOL) was used.
Manufactured by TECHNOLOGIES INC, LASER
CHECKER) was used to measure thin line breaks in the barcode. The results were as follows.

Thin line breakage Example 1 0% Comparative example 1 40% Example 2 0% In order to test the printability of the surface of thermal recording paper, resin totsupan ink (DICMV sticker ink) was applied on each thermal recording layer. The ink-applied surface was irradiated with ultraviolet light for 5 seconds. Next, cellophane tape was applied to the ink-applied surface, which was then peeled off, and the residual ink adhesion concentration was sensory-evaluated by three panelists. The results were as follows.

Ink Density Example 1 5 points Comparative Example 1 5 points Example 2 5 points In addition, each heat-sensitive recording paper was colored solid black as described above, and cottonseed oil was applied to the surface of the protective/printing layer, and the paper was heated at 40°C. When the color density was measured after being left for 24 hours, the following results were obtained.

Color density (surface oil resistance test) Example 1 1.15 Comparative example 1 1.15 Example 2 1.15 However, when the above cottonseed oil was applied to the back side of each thermal recording paper and left at 40°C for 72 hours, the color density of both was as follows. It became like that.

Color density (backside oil resistance test) Example 1 1.20 Comparative example 1 0.25 Example 2 1.25 [Effects of the invention] The thermal recording paper of the present invention can form recorded images with high definition, high sensitivity, and high gradation. The image quality is comparable to that of an image formed on printed lines by the conventional dry silver method, and is close to that of a photographic image. Therefore, the thermal recording paper of the present invention can be used for analysis, inspection, diagnosis, etc. in the field of electronic graphics.

Furthermore, the thermal recording paper of the present invention has excellent oil and fat resistance and has extremely high storage stability. Therefore, the thermal recording paper of the present invention can be used for barcode tabs, food labels, cosmetic labels, and the like.

Furthermore, since the surface of the support in the heat-sensitive recording paper of the present invention has extremely excellent flatness, a heat-sensitive coloring layer having a flat surface can be formed with a small amount of coating. It has high economical effects, such as making it possible to omit calender treatment for surface flattening.

[Brief explanation of drawings]

FIGS. 1 and 2 are cross-sectional explanatory views showing the structure of the thermal recording paper of the present invention, respectively. 1...Base paper, 2...White pigment kneaded polyolefin resin layer, 3...Matte polyolefin resin layer, 4...Thermosensitive coloring layer, 5...Protective printing layer,
6, 6a...Support, 7...Thermosensitive color recording layer.

Claims (1)

[Scope of Claims] 1. A support, formed on one surface of the support,
and a heat-sensitive color-forming layer containing a colorless or light-colored leuco dye and an acidic color-developing substance as a color-forming component; and a protective printing layer containing a white pigment, wherein the support is a base paper, and a white pigment-mixed polyolefin-based material formed between one surface of the base paper and the heat-sensitive coloring layer. A thermosensitive recording paper comprising: a resin layer; and a matte-treated polyolefin resin layer formed on the opposite side of the base paper. 2. The recording paper according to claim 1, wherein the polyolefin resin in the white pigment-kneaded polyolefin resin layer is selected from polyethylene, polypropylene, polybutene, polypentene, and copolymers or mixtures thereof. 3. The recording paper according to claim 1, wherein the polyolefin resin in the matted polyolefin resin layer is selected from polyethylene, polypropyne, polybutene, polypentene, and copolymers and mixtures thereof. 4. The recording paper according to claim 1, wherein the content of the white pigment in the white pigment-kneaded polyolefin resin layer is within the range of 5% to 20% (by weight). 5 a support, formed on one side of the support,
and a heat-sensitive color-forming layer containing a colorless or light-colored leuco dye and an acidic color-developing substance as a color-forming component; further, a water-soluble polymer substance formed on the heat-sensitive color-forming layer; 1. A heat-sensitive recording paper comprising a protective printing layer containing a water-proofing agent for a substance and a white pigment, the support being made of a white pigment-kneaded polyolefin resin synthetic paper. 6 The content of white pigment in the support is 30% to 50%.
% (by weight), claim 5
Thermal recording paper described in section. 7. The recording paper according to claim 5, wherein the polyolefin resin in the support is selected from polyethylene, polypropylene, polybutene, polypentene, and copolymers and mixtures thereof.