JPS6149890A - Thermal recording sheet - Google Patents

Abstract

PURPOSE:To obtain a thermal recordng sheet having high resistance to plasticizers, solvents and adhesion of scum and giving high clearness of printed images, by a construction wherein a thermal color forming layer is provided on a base, and a specified film being hydrophilic on the side for contact with the color forming layer is laminated thereon. CONSTITUTION:A base layer consiting of a paper, a synthetic paper, a synthetic resin sheet or the like, the thermal color forming layer comprising a color former, a color developer and a binder as main constituents, and a film layer selected from a biaxially stretched polyvinyl alcohol resin film, a triacetylcellulose film and cellophane and being hydrophilic on the side for contact with the color forming layer, are laminated on each other to produce a thermal recording sheet. The recording sheet can be produced by a method wherein the base layer and the film layer are pressed against each other by two press rollers while supplying a thermal color forming slurry therebetween, or a method wherein the thermal color forming layer is provided on either one of the base layer and the film layer and then the other is adhered by an adhesive or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a heat-sensitive recording sheet. More specifically, the present invention relates to a recording sheet that has a high degree of stability in the usage environment and is capable of forming an image corresponding to a thermal signal supplied through a thermal head or the like.

``Prior art'' A thermosensitive coloring composition containing a color forming agent, a color developer, and a binder as basic components is coated and dried on a support such as paper, and thermal energy is applied from above the thermosensitive coloring layer using a thermal head or the like. The method of recording characters and images by applying color to a coloring agent is widely known. However, paper coated with the heat-sensitive coloring composition described in Section 2 (hereinafter referred to as "thermal paper" in Section 1)
Because it has insufficient resistance to water, acids, plasticizers, solvents, wet friction, etc., and its surface is easily stained, it is used for example in red tags, carriage cards, bar code recording paper, labels, measuring equipment data recording paper, and outdoors. It cannot be used for display purposes, etc.

In order to improve these drawbacks, a method of providing a polymeric protective layer on the surface of thermal paper has been proposed. A method is known in which a mixed solution consisting of water-repellent molecules and a waterproofing agent is applied.

However, in this case as well, although the above-mentioned drawbacks can be improved to a certain degree, it is still not sufficient, and on the contrary, other problems such as adhesion of residue to the thermal head and sticking occur.

Therefore, methods have been proposed, such as adding an anti-sticking agent or the like to the polymeric protective layer, or selecting a particularly highly resistant component as a component of the heat-sensitive coloring layer. If this is done, the manufacturing process of the heat-sensitive recording sheet becomes increasingly complicated, the cost of chemicals increases, the advantage of the heat-sensitive recording sheet as a simple and inexpensive recording method is lost, and the practicality becomes poor. Furthermore, a method is also known in which a plastic film such as polyethylene terephthalate is laminated on the heat-sensitive coloring layer (% 1983-128347). However, even if the plastic film proposed here has a relatively high melting point, such as evaporated polyethylene terephthalate film, it may swell or swell due to heat softening during normal thermal printing using a thermal head. This is not preferable because it causes sticking. Furthermore, although it has been proposed to use expensive and poorly transparent films such as polyimide resin, this is also impractical.

``Problems to be solved by the invention'' Conventional heat-sensitive coloring sheets do not have sufficient resistance to various environmental conditions.
It is desired to provide a heat-sensitive recording sheet with high print clarity and high rigidity against water, plasticizers, solvents, wet friction, and abrasion scum adhesion by an inexpensive manufacturing method.

"Means for Solving the Problems" The present invention provides support layer holes, a heat-sensitive coloring layer (B) containing a color former, a color developer, and a binder as basic components, and a biaxially oriented polyvinyl alcohol-based film and a triacetyl cellulose film. Provided is a heat-sensitive recording sheet comprising a laminate consisting of a film layer (q) selected from the group consisting of , and hiserophane, and at least the surface in contact with the heat-sensitive coloring layer is hydrophilic. The body layer (5) may be paper, synthetic paper, cloth, non-woven fabric, synthetic resin sheet or metal plate, or a composite thereof.However, generally, at least the surface in contact with the thermosensitive coloring layer is paper, or It is preferably made of a synthetic resin to which the thermosensitive coloring layer can be adhered.For example, a triacetyl cellulose sheet whose surface has been treated with an aqueous caustic solution, a polystyrene sheet which has been subjected to a corona discharge treatment, or a polyester sheet coated with an adhesive can be used.

The basic components of the thermosensitive coloring layer (Bl) used in the present invention are a coloring agent, a color developer, and a binder. Those commonly used for coloring type thermal paper can be used.

Examples of color formers include 2-anilino-3-methyl-6-
Dinitylaminofluorane, 2-(0-fluoroanilino)-6-ethylaminofluorane, 2-anilino-
Examples include 3-methyl-6=piperidinofluorane, 3,3-bis(p=nidimethylaminophenyl-6-dimethylaminophthalide, benzoylleucomethylene blue, etc.), and these may be used alone or in combination. can.

Examples of color developers include bispheno-/l/A-S+)-
Octylphenol, 4. /1'-sulfonyldiphenol, bis-(3-allyl-4-hydroxyphenyl)
-sulfone, novolak type phenolic resin, benzyl p-hydroxybenzoate, and 3,5-di-α-methylbenzyl salicylic acid.

As the binder, a water-soluble or water-dispersible polymer compound is usually used. Examples include methoxycellulose, carboxymethylcellulose, polyvinyl alcohol, polyvinylpyrrolidone, starch, gelatin, casein, water-soluble styrene-maleic anhydride copolymer, polyvinyl acetate emulsion, poly(meth)acrylic acid ester polymer or copolymer. I can give you an emulsion.

The heat-sensitive color forming layer (Bl) used in the present invention may contain, in addition to the above-mentioned basic components, for example, a sensitizer, a bilge, a stabilizer, an adhesion improver, etc. These are commonly used in the industry. There is.

6. However, in the thermal recording sheet of the present invention, the thermosensitive coloring layer has the properties often required for general thermal paper, such as water resistance, plasticizer resistance, property to prevent residue from adhering to the thermal head, and property to prevent sticking. Since no special consideration is required for improvement, the selection of color formers, color developers, aqueous binders, and other auxiliary components is mainly based on color sensitivity, color density, color tone before and after color development, delamination strength, and price. This is relatively easy as it can be done from the viewpoint of

The thermochromic layer (Bl) is usually provided in the form of an aqueous thermochromic slurry containing the components listed above.

The film layer (q) used in the present invention must be hydrophilic at least on the surface in contact with the heat-sensitive coloring layer (B). Since the biaxially oriented polyvinyl alcohol film itself is hydrophilic, it can be used as is. Polyvinyl Examples of alcohol-based films include polyvinyl alcohol, heat-treated polyvinyl alcohol, boric acid-treated polyvinyl alcohol, polyvinyl formal, polyvinyl butyral, and other polyvinyl alcohol-crosslinked films.Triacetylcellulose film is made using caustic alkali It can be easily made hydrophilic by treatment with an aqueous solution.It can also be made hydrophilic by, for example, corona discharge treatment.

At least one side of cellophane is hydrophilic, unless it is double-sided moisture-proof cellophane.

These films not only safely protect the heat-sensitive coloring layer 03) from aqueous liquids, oil-based liquids, and wet friction, but also have good matching properties with thermal heads, and if a suitably adjusted thermal head is used. Smooth image recording is possible without creating debris or sticking. In addition, these films have extremely high transparency and a thermosensitive coloring layer (B
Since it is in close contact with 1 in terms of hydrophilicity, the printing clarity and coloring sensitivity are also good.

The thickness of the film layer (q) used in the present invention is preferably as thin as 0.000 mm, but is generally preferably from 0.003 am to 0.03 mm.

There are several methods for producing the heat-sensitive recording sheet of the present invention.

The simplest and most effective method is to supply the above-mentioned heat-sensitive coloring slurry between the support layer (5) and the hydrophilic surface of the film layer (Q), and then press them together with two pressure rollers and dry them.

In this case, since the heat-sensitive coloring slurry contains a binder component, when dried, it is converted into a heat-sensitive coloring layer (B), and also acts as an adhesive layer between the support layer (5) and the film layer (q). A heat-sensitive recording sheet having the structure of the invention can be easily obtained.By adjusting the viscosity of the heat-sensitive coloring slurry, the distance between the pressure rollers, and the pressure, a heat-sensitive coloring layer with an appropriate thickness can be obtained.

When using this method, at least during the manufacturing process,
At least one of the support layer (5) and the film layer (Q) must be water vapor permeable. It is preferred that the support layer (5) is water vapor permeable, like paper. However, biaxially oriented polyvinyl alcohol Cellulose based films, triacetyl cellulose films, and cellophane without moisture-proofing treatment are water vapor permeable, so when these are used as film layers, the support layer does not need to be water vapor permeable. Since the requirement is to evaporate the moisture in the heat-sensitive coloring slurry between the body layer (5) and the film layer (q), it is not possible to make it water vapor impermeable by laminating or treating with a waterproofing agent after drying. Not only is this not a problem, but it is actually preferable in terms of use.

Another method for producing the heat-sensitive recording sheet of the present invention is to apply a heat-sensitive coloring slurry to the surface of one side of the film layer (q) between the support layers, and dry it to form a heat-sensitive coloring layer (Bl). The other layer may be attached using water, adhesive, or adhesive.

The heat-sensitive recording sheet of the present invention has the above-mentioned laminate as a component, but has other layers on one or both sides, such as an overcoat layer, a laminate layer, a lubricating layer, an ultraviolet absorbing layer, a printing layer, and a magnetic recording layer. It goes without saying that layers, photosensitive layers, adhesive layers, etc. may be provided.

When the heat-sensitive recording sheet of the present invention is cut into the size of a red tag or the like and used, more stable durability can be imparted by stacking the cross sections of the sheet in a known manner.

``Effects of the invention'' When a thermal signal is applied to a thermal recording sheet, a corresponding clear, glossy and beautiful image can be obtained, and it is highly resistant to water, plasticizers, solvents, wet friction, and dirt adhesion. What you show is what you get.

The thermal recording sheet of the present invention includes recording paper for thermal printers,
Used for medical diagnosis recording paper, mechanical measurement recording paper, computer recording paper, communication recording paper for ships, heat-sensitive recording labels, cash cards, price tags, barcode display sheets, red tags, temperature indication sheets, and other water resistant materials. It can be widely used in fields where acid resistance, solvent resistance, oil resistance, plasticizer resistance, wet abrasion resistance, and clear glossy images are required.

"Example"<Preparation of heat-sensitive coloring slurry (F-1)> A mixture of the following compositions was prepared using a sand grinder to obtain an average particle size of 1.
It was pulverized and dispersed to ~3 μm to obtain liquids (A), (B), and (Q).

(a) Liquid: 2-(o-fluoroanilino)-6-diethylaminofluor 12 parts 25 parts 25% polyvinyl alcohol aqueous solution 20 parts Water 55 parts (1
3) Liquid: Bisphenol 1. 1-3 part 25
% polyvinyl alcohol aqueous solution 16 parts water 71 parts (
Q solution: p-acetotoluicide 13 parts Calcium carbonate 21 parts 25% polyvinyl alcohol aqueous solution 16 parts Water 5o parts CA
[, (g)) solution, and (Ω solution) were mixed in a ratio of 6:47:47 to obtain a thermosensitive coloring slug IJ-(F-1).

Example 1 36 g of the above heat-sensitive coloring slurry IJ-(F-1) was placed between high-quality paper (basis weight 132.5 g/m) and biaxially stretched vinylon film ("BOVLON" manufactured by Nippon Film ■, 12 μm thick).
While injecting it uniformly at a ratio of /m, press it with two rolls,
It was made into a laminated sheet. Heat-sensitive recording sheet by drying at 30℃■
I got it.

Example 2 The above heat-sensitive coloring slurry (F-1,) was uniformly injected between high-quality paper (basis weight 132.5 g/m) and cellophane (PT+-300 manufactured by Futamura Chemical Co., Ltd.) at a rate of 36 g/g/g. While doing so, they were pressed together using two rolls to form a laminated sheet. It was dried at 30°C to obtain a heat-sensitive recording sheet (■).

<Preparation of heat-sensitive coloring slurry (F-2)> A mixture of the following compositions was ground using a sand grinder to an average particle size of 1
Powdered sand was dispersed to a thickness of ~3 μm to obtain liquids (B) and (Ω).

(5) Liquid: 2-anilino-3-methyl-6-dinithylaminofluorane 25 parts 25% polyvinyl alcohol aqueous solution 20 parts Water 55 parts C
Bl solution: Bisphenol A 13 parts 25
% Polyvinyl alcohol water faW 16 parts Water 71 parts (
Liquid q: Carnauba wax 18 parts Calcium carbonate 21 parts 25% polyvinyl alcohol aqueous solution 16 parts Sorbitan monostearate 4 parts Water 41 parts Prison liquid, (Bl liquid, and (Q liquid) were mixed in a ratio of 6:47:47. A thermosensitive coloring slurry!7-(F-2) was obtained.

Example 3 One side of a triacetyl rose sheet (“Fujitac” 190 μm thick mat made by Fuji Photo Film ■) was heated to 45° C.
It was treated with a caustic soda aqueous solution for 30 seconds, washed with water, and dried. A heat-sensitive coloring slurry 17-' (F = 2
) was applied at a rate of 32 g/m'' and dried at room temperature to form a thermosensitive coloring layer.

Next, one side of another triacetyl cellulose film ("Fujitac", 18 μm clear, manufactured by Fuji Photo Film ■) was treated with an IN aqueous sodium hydroxide solution at 45° C. for 30 seconds, washed with water, and dried. Wet this treated surface evenly with water,
It was pressed onto the above heat-sensitive coloring layer and dried. The obtained white laminated sheet was cut into a rectangle measuring 587 mm x 899 m to obtain a card-type heat-sensitive recording sheet (2) with good snappability.

(Comparative Example) The heat-sensitive coloring slurry (F-1,) was uniformly applied at a rate of 36 g/m'' on high-quality paper (]-32.5 g/m) and dried.

A mixture of 3.2 parts of roll melamine resin aqueous solution was applied and dried. The thickness of the protective layer after drying was about 5 μm.

(Comparative Example 3) In the same manner as in Example 3, except that instead of the 18 μm thick “Fujitac”, one side of a 16 μm thick polyethylene terephthalate film (“Lumirror” manufactured by Toshi ■) was subjected to corona discharge treatment. The treated surface was pressed so that it was in contact with the heat-sensitive coloring layer.

<Quality performance test> Color density: The test piece was pressed against a hot plate at 140° C. for 5 seconds, and the color density was measured using a Macbeth reflection densitometer RD-91.4.

Water resistance: A test piece was immersed in tap water for 1 hour, then gently shaken in the water and taken out, and the degree of damage was observed.

Plasticizer resistance: A polyvinyl chloride wrap film was brought into contact with both sides of the test piece colored by the above method under a pressure of 20 g/s2, and the test piece was left at room temperature for 7 days to observe the degree of discoloration.

Solvent resistance: 1 part of disinfectant ethanol was dropped on the colored surface of the test piece, and after 10 seconds, the degree of color fading was observed when it was pressed with filter paper.

Wet abrasion resistance: The colored surface of the test piece was soaked in tap water and lightly rubbed 10 times with a tissue paper that had been rubbed in the palm of the hand, and the condition of the surface was observed.

Adhesion of residue to thermal head: Each thermal recording sheet was printed up to 1000 times in a row using a thermal recording barcoder, and the degree of adhesion of residue was observed.

Visibility of printing: Each heat-sensitive recording sheet was printed with a thermal recording barcoder, and the condition of the film surface and the clarity of the printing were judged with the naked eye.

The test results are shown in the table below. In the table, ◯ indicates no abnormality, △ indicates moderate damage, and X indicates significant damage.

=17-

Claims (1)

[Claims] (1) A support layer (A), a thermosensitive coloring layer (B) containing a color former, a color developer, and a binder as basic components, and selected from the group consisting of a biaxially oriented polyvinyl alcohol film, a triacetyl cellulose film, and cellophane. 1. A heat-sensitive recording sheet comprising, as a constituent element, a laminate comprising a film layer (C) which is hydrophilic and at least the surface in contact with the heat-sensitive coloring layer is hydrophilic.