JPH063659U - Thermal recording - Google Patents

Abstract

(57) [Summary] [Object] The present invention provides a heat-sensitive recording material having good recording characteristics and excellent durability, using a cloth as a support, without impairing the texture unique to the cloth. [Structure] A cloth having a weaving density of 30 fibers / cm or more and a weaving gap of 150 μm or less is used as a support, an under layer is formed on the surface of the support, and a colorless or light-colored leuco dye and a color development capable of thermally coloring the leuco dye. A heat-sensitive recording comprising a thermosensitive coloring layer containing an agent and an aqueous resin as main components, and a protective layer containing the aqueous resin as main components, which are sequentially laminated, and a rewetting adhesive layer provided on the back surface. body. [Effect] The thermosensitive recording medium of the present invention has a texture as a cloth, has a durability that can be sufficiently adapted for outdoor use, and has a good workability that can be applied only by moistening with water. It is a thing. Since it has such characteristics, it can be used in various fields such as design-related, event-related, and advertisement-related fields.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a thermal recording medium, and more specifically, by using a specific fabric as a support, it provides a thermal recording medium having good recording characteristics and excellent durability without impairing the texture peculiar to the fabric. It is a thing.

[0002]

[Prior art]

 A heat-sensitive recording material having a heat-sensitive recording layer mainly composed of a colorless or light-colored leuco dye and a color developer which reacts with the dye to develop a color is disclosed in JP-B-45-14035 and widely put into practical use. Has been done. A thermal printer or the like with a built-in thermal head is used to perform recording on this thermal recording medium, but such thermal recording method is less noisy during recording than other conventional recording methods. With the development of the information industry, in the facsimile and computer fields, the features such as no need for developing and fixing, maintenance-free, relatively inexpensive and compact equipment, and very clear color development are obtained. Widely used for various measuring instruments and labels. In recent years, due to the speed and simplicity of the heat-sensitive recording system, the use of the heat-sensitive recording material has been promoted in the fields of design, event, advertisement and the like. In these fields, due to the nature of its business, for example, high-definition recording on materials such as cloth or leather that have a specific form other than paper, or when used by being stuck on an exhibition board or used outdoors. Since there are many types, it is necessary for the thermal recording material itself to have excellent durability in addition to the durability of the recorded image. However, the conventional heat-sensitive recording material is one in which a heat-sensitive recording layer is coated with paper, synthetic paper, or a synthetic resin film as a support, and it is difficult to apply it to the wide range of uses. For example, when used as a large area recording material such as drawings or posters, there are restrictions on handling such as problems of crease marks when folded, and normal recording using paper as a support. The body had difficulty in durability and water resistance. In addition, when used by pasting, there are problems such as fading of a recorded image due to solvent penetration in the case of a solvent type adhesive and wrinkling of a paper support in the case of an aqueous type adhesive. The present situation is that no thermal recording material has been developed that solves these problems, has the feel of cloth, and is excellent in recording suitability.

[0003]

[Problems to be solved by the device]

 In view of the above circumstances, the present invention provides a heat-sensitive recording material having good recording characteristics while using a cloth as a support and maintaining the texture and excellent durability peculiar to the cloth.

[0004]

[Means for Solving the Problems]

 In the present invention, a cloth having a weave density of 30 / cm or more and a weaving gap of 150 μm or less is used as a support, and an underlayer, a colorless or light-colored leuco dye, and a coloring material for coloring the leuco dye under heat are formed on the surface of the support. A heat-sensitive coloring layer mainly composed of a colorant and an aqueous resin, and a protective layer mainly composed of the water-based resin, which are sequentially laminated, and a rewetting adhesive layer is provided on the back surface. It is a recording body. That is, the thermosensitive recording medium of the present invention has a layer structure shown in FIG. 1, and an under layer 2, a thermosensitive coloring layer 3 and a protective layer 4 are sequentially laminated on the surface of a cloth 1 as a support. The rewetting adhesive layer 5 is provided on the back surface.

The cloth used as the support in the present invention has a weaving density of 30 yarns / cm or more and a weaving gap of 150 μm or less, particularly preferably a weaving density of 40 to 200 yarns / cm, and a weaving gap of 10 yarns / cm. ˜100 μm. Here, in the case where the weaving density of the fabric is 30 threads / cm or more and the weaving gap is 150 μm or less, the fabric that does not satisfy either one has an underlayer or a thermosensitive coloring layer because the weaving yarn is too thick or the gap between the weaving yarns is too large. There is a problem in that it is difficult to form, and even if it can be formed, there is a problem in that the surface of the thermal recording material is affected by the unevenness of the surface of the fabric, which impairs the recording characteristics. Also, if the weaving density exceeds 200 yarns / cm, the weaving yarns that make up the fabric may become too thin, and the strength as a support may be impaired. However, a narrow fabric is not preferable because it is difficult to manufacture and has a cost problem. In the present invention, by using the specific support as described above, that is, the support having a high weave density and a narrow gap between the weaving yarns constituting the fabric, it is possible to prevent the backing of the coating liquid and to provide a uniform coating layer. Can be formed, and good recording characteristics can be obtained. The weaving density and weaving gap in the present invention are obtained by taking a photograph of the surface of the cloth with a stereoscopic microscope and determining the weaving form. If there is a difference in the weaving density and the weaving gap between the warp direction and the weft direction due to the relationship of the weave of the cloth, the difference is averaged.

The fabric in the present invention is not particularly limited in its material as long as it has the above-mentioned specific form, that is, the weave density is 30 yarns / cm or more and the weaving gap is 150 μm or less, and will be described below. As described above, the heat calendar treatment may be performed or may not be performed. As the material, for example, a sheet-like material made of various fibers such as cotton, rayon, acetate-based, polyester-based, polyacrylic-based, polyamide-based is used. Further, it is preferable to use, as a support, a fabric having a surface Beck smoothness (according to JIS-P8119) of 5 seconds or more, preferably 10 seconds or more, by subjecting the above-mentioned cloth to a heat calendar treatment or the like. This improvement in smoothness allows the under layer, the thermosensitive coloring layer and the protective layer, which are laminated on the surface of the fabric, to be formed more uniformly, which is effective in improving recording characteristics by reducing uneven recording. Is. Further, since the underlayer can be formed thinner by improving the smoothness of the fabric as the support, it is effective in maintaining the texture of the fabric.

For the under layer in the present invention, various solvent-soluble resins, water-soluble resins, aqueous emulsion resins and the like can be appropriately used, and a filler can be used if necessary. Here, as the resin used, a resin having a glass transition temperature of 50 ° C. or lower, preferably 30 ° C. or lower is particularly suitable for achieving the object of the present invention. As the binder having a glass transition temperature of 50 ° C. or lower, which is preferably used for the under layer, various solvent-soluble resins, water-soluble resins or aqueous emulsions can be applied, and examples thereof include polyethylene, polypropylene, poly-1-butene, polybutadiene, Polyisobutylene, polychloroprene, polypentadiene, polymethyl vinyl ether, polyethyl vinyl ether, polyvinyl acetate, polyvinyl chloride acetate, polyvinylidene chloride, polyvinylidene fluoride, methyl polyacrylate, ethyl polyacrylate, propyl polyacrylate, poly 2-hydroxyethyl acrylate, propyl polymethacrylate, butyl polymethacrylate, hexyl polymethacrylate, octyl polymethacrylate, 2-ethylhexyl polymethacrylate, nitrocellulose, Examples thereof include homopolymers such as acetyl cellulose, and further, copolymers containing at least one monomer component that forms a polymer having a glass transition temperature of 50 ° C. or less, such as the above, specifically, Examples thereof include, but are not limited to, a styrene-butadiene copolymer, a styrene- (meth) acrylic acid ester copolymer, and an ethylene-vinyl acetate copolymer. Among these polymers, an aqueous emulsion of styrene-butadiene copolymer or an aqueous emulsion of styrene- (meth) acrylic acid ester copolymer having a glass transition temperature of 50 ° C or lower, preferably 30 ° C or lower is suitable. By using these water-based emulsions, not only the durability such as water resistance is improved, but also an excellent effect that crease marks are not easily formed especially when folded is exhibited.

The glass transition temperature referred to in the present invention means a temperature at which a glassy hard state is changed to a rubbery state when a polymer substance is heated. Generally, the volume, specific heat, and Various physical properties such as elastic modulus and refractive index change. The glass transition temperature is obtained by measuring thermodynamic properties such as coefficient of thermal expansion and heat capacity, and mechanical properties such as complex elastic modulus. The glass transition temperature of the copolymer can also be determined from the glass transition temperature of each homopolymer of the components constituting the copolymer, by the ratio of the components of the copolymer.

Fillers that can be used in the under layer include inorganic and organic pigments such as heavy and light calcium carbonate, aluminum hydroxide, titanium oxide, zinc oxide, barium sulphate, talc, clay, calcined clay, satin. Examples thereof include white, kaolinite, polyolefin particles, polystyrene particles, urea-formalin resin particles and the like. The compounding ratio of the binder and the filler in the under layer is in the range of 10: 0 to 1: 9, preferably 9: 1 to 2: 8 in view of recording characteristics and crease characteristics. The coating amount of the underlayer is preferably adjusted to about 0.5 to 15 g / m ² , and more preferably ² to 10 g / m ² .

The underlayer having the composition as described above forms a thermosensitive color forming layer uniformly to improve recording characteristics, and prevents the thermosensitive color developing layer from peeling or falling off from the support, and is further folded. It is provided to make it difficult for crease marks to form. In this case, if a resin having a glass transition temperature of more than 50 ° C. is used, the under layer provided on the fabric as the support will be hard, and the fabric will be soft in relation to the flexibility of the fabric support. There is a risk that the texture may be impaired, the coating may be lost due to cracks in the under layer when folded, crease marks may be generated, and the recorded image may be discolored due to penetration of a solvent or the like.

Regarding the relationship between the under layer and the fabric support, a specific fabric support used in the present invention, that is, a fabric support having a weave density of 30 / cm or more and a weaving gap of 150 μm or less is used. As a result, when the under layer is provided, the under layer paint permeates appropriately into the gaps between the weaving yarns of the fabric support, improving the binding force between the fabric support and the under layer, and at the same time, as described above. Excellent smoothness can be obtained, and the thermosensitive coloring layer can be uniformly formed to achieve good recording characteristics, which is an excellent effect.

As the leuco dye used in the thermosensitive coloring layer in the present invention, any leuco dye applicable to this type of thermosensitive recording material can be used, for example, 3,3-bis (p-dimethylaminophenyl) phthalide, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (CVL), 3,3-bis (p-dimethylaminophenyl) -6-diethylaminophthalide, 4-hydroxy-4'- Triphenylmethane compounds such as dimethylamino triphenylmethane lactone and 4,4'-bisdihydroxy-3,3'-bisdiaminotriphenylmethane lactone, for example, 3-dimethylamino-6-methoxyfluorane, 3,6-bis -Β-methoxyethoxyfluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3,7-bi Diethylaminofluoran, 3-diethylamino-7-methoxyfluorane like fluoran-based, spiropyran, auramine, can use various leuco dyes phenothiazine and the like. Further, as a developer, organic acids such as oxalic acid, maleic acid, citric acid, stearic acid, benzoic acid, and gallic acid, and catechol, resorcin, hydroquinone, α-naphthol, β-naphthol, 3,5-xylenol are used. , Thymol, pyrogallol, phloroglucin, phloroglucin carboxylic acid, 4-tert-butylphenol, 4-phenylphenol, 4-hydroxydiphenoxide, 4-hydroxyacetophenone, methyl-4-hydroxybenzoate, 4-tert-octylcatechol, 4,4'-Secondary butylidene diphenol, 2,2'-dihydroxydiphenol, 4,4'-isopropylidene diphenol (bisphenol A), 2,2'-methylenebis (4-methyl-6-tertiary) Butylphenol), 4 , 4'-Cyclohexylidenephenol, 4,4'-isopropylidene bis (2-chlorophenol). In addition thereto, phenolic compounds such as phenol formaldehyde resin, novolac type phenol resin, halogenated novolac type phenol resin and the like can be mentioned.

In the thermosensitive coloring layer of the present invention, an aqueous resin is used as a binder, that is, a water-soluble polymer or a water-dispersible polymer, and examples thereof include polyvinyl alcohol, modified polyvinyl alcohol, vidroxyethyl cellulose, and methyl cellulose. , Carboxymethyl cellulose, starch and its derivatives, casein, gelatin, sodium alginate, polyvinylpyrrolidone, polyacrylamide, modified polyacrylamide, alkaline aqueous solution of isobutylene-maleic anhydride copolymer resin, diisobutylene-maleic anhydride. Alkaline aqueous solution of copolymer resin, water-soluble resin such as aqueous solution of styrene-maleic anhydride copolymer resin, aqueous polyester, aqueous polyurethane, (meth) acrylate copolymer, styrene- (meth) Acry Water-dispersible resins such as acid ester copolymers, polyvinyl acetate, polyvinylidene chloride and derivatives thereof can be used alone or in combination.

In the thermosensitive coloring layer, inorganic and organic pigments as a filler, such as heavy and light calcium carbonate, aluminum hydroxide, titanium oxide, zinc oxide, barium sulfate, talc, clay and satin. White, kaolinite, polyolefin particles, polystyrene particles, urea, -formalin resin particles and the like can be added to improve the sharpness of the color image. Further, in order to improve the recording sensitivity, various commonly used heat-fusible substances may be added to the heat-sensitive color forming layer, if necessary. Examples of the heat-fusible substance include organic compounds having an appropriate melting point. Examples thereof include higher fatty acid amides such as stearic acid amide, animal waxes such as beeswax, shellac wax, and vegetable waxes such as carnauba wax. Mineral wax such as montan wax, paraffin wax, wax such as microcrystalline wax, higher fatty acid, higher fatty acid ester, aromatic carboxylic acid ester such as dimethyl terephthalate, diphenylphthalate, alkylnaphthalene derivative, alkyldiphenyl derivative, An alkyl terphenyl derivative or the like is used. The usage ratio of the leuco dye and the developer used in the thermosensitive coloring layer is appropriately selected depending on the types of the leuco dye and the developer to be used, and is not particularly limited. The amount is 100 to 500 parts by weight, preferably 150 to 400 parts by weight, relative to 100 parts by weight of the dye. The coating amount of the heat-sensitive coloring layer, typically 1 to 15 g / m ² approximately, and preferably from 2 to 10 g / m ^2.

The protective layer in the thermosensitive recording medium of the present invention is provided on the thermosensitive coloring layer as a main component of an aqueous resin having excellent chemical resistance and good film-forming property, and the thermosensitive coloring caused by contact with oils and solvents. It has a barrier effect for preventing background color development of the layer and fading of the recorded area, as well as improving scratch resistance and preventing the coating film from missing at the folded area. As the water-based resin used in the protective layer, at least one selected from water-soluble resins and water-dispersible resins is used. Specifically, the same resin as the binder used in the thermosensitive coloring layer is used. can give. In addition, a water-proofing agent is added as necessary to obtain more excellent water resistance. As the waterproofing agent, glyoxal, chrome vanadium, melamine resin, melamine formaldehyde resin, polyamide resin, polyamide-epichlorohydrin resin, zirconium compound and the like can be added. Further, in order to improve the matching property with the thermal recording head, it is preferable to add a filler, metal soap or the like to the protective layer. Examples of the filler include heavy and light calcium carbonate, aluminum hydroxide, titanium oxide, zinc oxide, barium sulfate, talc, clay, satin white, kaolinite, polyolefin particles, polystyrene particles, urea-formalin resin particles, etc. Examples of the metal soap include zinc stearate and calcium stearate. The coating amount of the protective layer is about 1 to 15 g / m ² , but if the coating amount is too large, the heat transfer to the thermosensitive color developing layer will be poor and the recording sensitivity will decrease. Is deteriorated and the scratch resistance and the crease characteristics are deteriorated, so that it is preferably about ² to 6 g / m ² .

The rewetting adhesive layer on the back surface of the support in the present invention is mainly composed of an adhesive which has a characteristic that it is normally in a dry state and becomes tacky by absorbing moisture. The rewetting adhesive used is not particularly limited, and examples thereof include polyvinyl alcohol, polyvinyl alcohol-polyvinyl acetate mixture, glue, gum arabic, and dextrin. Further, an additive such as a pigment may be used in the rewetting adhesive layer to improve the adhesive strength. The application amount of the rewetting adhesive layer is about 5 to 50 g / m ² , preferably about 10 to 30 g / m ² .

In the heat-sensitive recording material of the present invention, in order to form the under layer, the heat-sensitive color forming layer, the protective layer and the rewetting adhesive layer, a coating solution having the composition as described above is used, for example, air knife coating or roll. It may be applied by a known coating method such as coating, bar coating, blade coating and the like, and dried. Here, the coating liquid for the thermosensitive color developing layer is such that the leuco dye and the developer are pulverized by a media type wet disperser in an aqueous resin that functions as a dispersant and a binder, respectively, and the particle size of the substance to be dispersed. Is preferably 5 μm or less, and more preferably 2 μm or less. Furthermore, after forming each of the above layers, in order to improve the adhesion with the thermal head and improve the recording sensitivity, a calender device consisting of metal rolls and elastic rolls was used, and the Beck smoothness was used as the surface smoothness. It is desirable to smooth the surface for 50 seconds or longer, preferably 300 seconds or longer.

[0018]

【Example】

Hereinafter, a detailed description of the present invention will be given according to embodiments. All parts in the examples represent parts by weight. Example 1 A polyester calendered fabric (weaving density of 40 strands / cm, weaving gap of 50 μm, Beck smoothness of 20 seconds) was used as a support, and after the coating material having the following composition was dried on the fabric, Was coated and dried to form an underlayer so that the coating amount was 5 g / m ² .・ Clay (Alpha coat manufactured by Anglo American Clay Co., Ltd.) 40 parts ・ Water 60 parts ・ Styrene-butadiene copolymer aqueous emulsion (Tg 0 ° C., solid content 48%) 125 parts Next, in order to manufacture a coating material for a thermosensitive color developing layer. A liquid [A] and a liquid [B] having the following compositions were pulverized using a sand grinder so that the average particle diameters of the leuco dye and the developer would be 1.5 μm to prepare a dispersion. [A] Liquid-30 parts of 4-hydroxybenzoic acid benzyl ester-Light calcium carbonate (Shiraishi Industry Co., Ltd., Brilliant 15) 20 parts-Polyvinyl alcohol 10% aqueous solution (Kuraray Co., PVA203) 50 parts-Water 50 parts [B ] Liquid-3-N-ethyl-N-isoamylamino-6-methyl-7-anilinofluorane 15 parts-Polyvinyl alcohol 10% aqueous solution (Kuraray PVA203) 15 parts-Water 20 parts As described above. To 150 parts of the obtained solution [A] and 50 parts of the solution [B], 100 parts of a 10% aqueous polyvinyl alcohol solution (PVA-117 manufactured by Kuraray Co., Ltd.) was added and mixed by stirring to form a coating material for the thermosensitive color developing layer, A thermosensitive coloring layer was formed by coating and drying the undercoat layer so that the coating amount after drying was 4 g / m ² . Next, a coating material having the following composition was prepared as a coating material for the protective layer, and the coating material was applied onto the thermosensitive coloring layer so that the dry weight was 4 g / m ² . -Carboxyl-modified polyvinyl alcohol 10% aqueous solution (Nippon Gosei Chemical Co., Ltd., Gosenol T-330) 100 parts-40% kaolin clay aqueous dispersion 20 parts-Zinc stearate 30% aqueous dispersion 5 parts-Polyamide epichlorohydrin resin 20% Aqueous solution (Showa High Polymer Co., Ltd., Polyfix 203) 20 parts Water 15 parts Further, polyvinyl alcohol-polyvinyl acetate mixture emulsion (Kanebo NSC Co., Reyn VV-987) was used as a paint for rewetting adhesive layer. After coating and drying on the back surface of the support so that the coating amount is 20 g / m ² , a rewetting adhesive layer is formed, and then the surface of the protective layer is smoothed with a super calendar, and the heat-sensitive recording of the present invention is performed. The body was made.

Examples 2 to 4 The thermosensitive recording medium of the present invention was prepared in the same manner as in Example 1 except that the cloth shown in Table 1 was used as the support. Example 5 In Example 1, in place of the styrene-butadiene copolymer aqueous emulsion of the coating material for the under layer, a styrene-methyl methacrylate-2-ethylhexyl methacrylate aqueous emulsion (Tg 24 ° C., solid content 40) was used. %) Was used, and a thermosensitive recording medium of the present invention was manufactured in exactly the same manner as in Example 1.

Comparative Example 1 A thermal recording medium for comparison was prepared in the same manner as in Example 1 except that the under layer was not provided. Comparative Example 2 A thermal recording medium for comparison was prepared in the same manner as in Example 1 except that the protective layer was not provided. Comparative Examples 3 to 5 A thermal recording medium for comparison was prepared in the same manner as in Example 1 except that the cloth shown in Table 1 was used as the support.

[Table 1]

The thermal recording materials of Examples 1 to 5 and Comparative Examples 1 to 5 obtained as described above were evaluated in terms of recording characteristics and durability by the following methods, and the results are shown in Table 2. . 1. Recording density and recording image quality evaluation (recording characteristics) Recording was carried out with a thermal printing device manufactured by Matsushita Electronic Components Co., Ltd. at an applied power of 0.5 W / dot and a pulse width of 1.0 msec. The recording density was evaluated by measuring with a total of RD-914. In addition, the recorded image was observed to evaluate the white state of the recording. ∘: No white spots are found ○: White spots are scarce Δ: White spots are noticeable even in normal recording ×: White spots are large and cannot be used practically 2. Crease characteristics, lack of coated surface (durability) A thermal recording material is folded in two and the trace of the folded portion is evaluated. ○ ・ ・ ・ No traces on the bent part △ ・ ・ ・ Slight traces on the bent part × ・ ・ ・ Remaining creases on the bent part Hand squeeze the thermosensitive recording medium to check for missing coating surface ○・ ・ ・ There is no missing coating surface △ ・ ・ ・ Slightly missing coating surface × ・ ・ ・ White powder is generated due to missing coating surface

[Table 2] As is clear from the results in Table 2, the thermal recording medium of the present invention has high recording density, excellent recording image quality, and excellent folding characteristics and durability unique to the fabric. It was recognized to have. In addition, when the rewetting adhesive layer of the thermal recording medium of the example was moistened with water and then applied to the display board, it could be easily applied without problems such as wrinkles.

[0022]

[Effect of device]

 The thermosensitive recording medium of the present invention has good recording characteristics and excellent durability without deteriorating the texture as a fabric, and since it has a re-wetting adhesive layer, it can be appropriately wetted with water. It can be attached and has good workability without problems such as generation of wrinkles. Moreover, since it has such characteristics, it can be well adapted to outdoor use and can be used in various fields such as design, event, and advertising.

[Brief description of drawings]

FIG. 1 is a sectional view showing the layer structure of a thermosensitive recording medium of the present invention.

[Explanation of symbols]

 1 Fabric 2 Under Layer 3 Thermosensitive Coloring Layer 4 Protective Layer 5 Rewetting Adhesive Layer

Claims (3)

[Scope of utility model registration request] 1. An underlayer, a colorless or light-colored leuco dye, and the leuco dye are heat-developed on the surface of the support using a fabric having a weave density of 30 fibers / cm or more and a weaving gap of 150 μm or less as a support. A thermosensitive coloring layer containing a developer and an aqueous resin as main components, and a protective layer containing the aqueous resin as main components, which are sequentially laminated, and a rewetting adhesive layer is provided on the back surface. Thermal recording material. 2. The under layer has a glass transition temperature of 50.
A resin having a temperature of ℃ or less as a main component is used.
The heat-sensitive recording material described. 3. The heat-sensitive recording according to claim 2, wherein the resin having a glass transition temperature of 50 ° C. or lower is a styrene-butadiene copolymer emulsion or a styrene- (meth) acrylic acid ester copolymer emulsion. body.