JPH03243391A - Image forming material for sublimation transfer - Google Patents

Abstract

PURPOSE:To obtain an image forming material for sublimation transfer excellent in sensitivity and fixing properties by holding a clayey mineral composite wherein a quaternary ammonium ion or a quaternary phosphonium ion are bonded between clayey mineral layers by ion exchange and quaternary ammonium perchlorate or quaternary phosphonium perchlorate is held as an intercalary compound on a substrate. CONSTITUTION:An image forming material for sublimation transfer is formed by holding a clayey mineral composite wherein a quaternary ammonium ion or a quaternary phosphonium ion is bonded between clayey mineral layers by ion exchange and quaternary ammonium perchlorate or quaternary phosphonium perchlorate is held as an intercalary compound on a substrate. When the intercalation between the clayey mineral layers having a laminar structure is utilized as a fixing mechanism and the decomposition heating due to the thermal stimulation of org. perchlorate held between the clayey mineral layers is utilized as a sensitizing mechanism, desired effect is obtained and sensitivity and fixing properties can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming material for sublimation transfer used in thermal transfer printers and the like, and particularly to improvements in its sensitivity and fixability.

[Summary of the Invention] The present invention uses a clay mineral having a layered structure as a dye-receiving mechanism of an image forming material for sublimation transfer, and ion exchange bonds an exchangeable organic cation between the layers. By retaining the perchlorate as an intercalant, the dye that is sublimated and transferred from the dye supply source such as the ink ribbon by heating is received and stably fixed in the interlayer area, and at the same time, the organic perchloric acid The aim is to obtain a sensitizing effect through the heat generated by the decomposition of the salt.

[Prior Art] A technique in which thermal energy is applied from a thermal head or the like to an ink ribbon having an ink layer to transfer dye contained in the ink layer to recording paper is known as so-called transfer type thermal recording. This transfer type thermal recording uses a melt transfer method in which a dye mixed with wax and applied to an ink ribbon is melted by heat and transferred to recording paper, and a sublimation dye applied to an ink ribbon is sublimated by heat. It is broadly divided into sublimation transfer method, in which the image is transferred onto recording paper. Among these, the latter sublimation transfer method is being developed in various fields because it has the advantage of being able to form full-color images and relatively easily obtaining density gradations.

Image-forming materials such as photographic paper used in the sublimation transfer method are generally formed by laminating a dye-receiving layer mainly made of resin such as polyester on a base material such as two layers of natural paper or a polymer film. It has a configuration.

An image is formed by selectively heating an ink ribbon containing a sublimable dye in the dye-receiving layer in accordance with an image signal while it is brought into contact with the dye-receiving layer. Here, as the above-mentioned sublimable dye, disperse dyes are widely used because it is necessary to dye the resin which is the main component of the dye-receiving layer.

[Problem to be solved by the invention]

Incidentally, in order to realize practical thermal recording using the sublimation transfer method, it is desired to improve the sensitivity and the storage stability after image formation more than ever before.

In other words, the improvement in sensitivity means a reduction in the thermal energy required for transfer. The sublimability of sublimable dyes is determined by the compound, and the amount of migration is also determined by the capacity of the dye-receiving layer, etc., so in order to optimize these conditions and achieve high-speed recording, it is necessary to This is because the key is whether an image of practical density can be formed using thermal energy.

On the other hand, storage stability refers to how well the fixation of the formed image can be improved. Images formed by the sublimation transfer method have the disadvantage of fading when heated, and this is an unavoidable problem in principle since a sublimable compound is used as the dye. The higher the sublimation property is selected as the sublimation dye, the more remarkable the deterioration of the fixing property becomes. Since most of the sublimable dyes used here are basic dyes, attempts have been made to improve the fixing properties by making the dye-receiving layer acidic, but no satisfactory results have been obtained.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide an image forming material for sublimation transfer that has excellent sensitivity and fixing properties.

[Means to solve the problem]

The present inventors considered that the above-mentioned problem could be solved if the dye-receiving layer had a fixing mechanism and a sensitizing mechanism. Utilizing intercalation between the layers of
In addition, as a sensitization mechanism, if the decomposition heat generated by thermal stimulation of the organic perchlorate held between the layers of the above-mentioned clay mineral is used,
It has been found that the desired effect can be obtained.

The image-forming material for sublimation transfer according to the present invention is proposed based on the above-mentioned findings, in which quaternary ammonium ions or quaternary phosphonium ions are ion-exchange bonded between the eyebrows of clay minerals, and perchloric acid quaternary It is characterized in that a clay mineral complex in which ammonium or quaternary phosphonium perchlorate is held as an intercalant is held on a substrate.

First, clay minerals used in the present invention include those having a layered structure and having exchangeable cations between the layers. A typical example is montmorillonite group minerals.

Montmorillonite group minerals have the following general formula % formula %) [However, X = Af, Fe (III), Mn (I [
l), Cr(I[l), Y=Mg, Fe(II)
, Mn(II), Nt.

ZnLi, Z=Si, Al, W=, Na, Ca, H2O represents interlayer water, and m represents an integer. ] It is a clay mineral with a three-layer structure. Depending on the combination of X and Y and the difference in the number of substitutions, montmorillonite, magnesian montmorillonite, iron montmorillonite, iron magnesian montmorillonite, beidellite, aluminian beidellite, nontronite, aluminian nontronite, saponite, aluminian saponite, hectorite, sauconite, etc. There are many types of these, but in addition to these natural products, synthetic products in which the ○H group in the above formula is substituted with fluorine can also be produced manually.

In addition to the above-mentioned montmorillonite group minerals, mica group minerals such as sodium silicic mica, sodium taeniolite, and ridium taeniolite can be used. Kaolinite has a layered structure but does not have exchangeable cations between the layers.
Talc, pyrophyllite, etc. are unsuitable. Furthermore, although zeolite has alkali metal ions or alkaline earth metal ions as exchangeable cations, its structure is network-like and the pore size is small, so its practical performance is somewhat inferior.

These clay minerals are used with quaternary ammonium ions or quaternary phosphonium ions bonded by ion exchange between their layers. Here, the above-mentioned quaternary phosphonium ion is
Refers to tetraalkylphosphonium ions and tetraarylphosphonium ions. Hereinafter, each of these ions will be collectively referred to as an exchangeable organic cation in this specification.

These exchangeable organic cations expand the interlayer distance of clay minerals due to the steric effect of their hydrophobic chains, and change the originally hydrophilic interlayers of clay minerals into a hydrophobic environment, resulting in intercalants, which will be described later. It plays a role in making it easier to retain organic compounds such as quaternary ammonium perchlorate, quaternary phosphorous perchlorate, or sublimable dyes that migrate from the ink ribbon during printing. The four side chains of these exchangeable organic cations are selected from alkyl groups or aryl groups having 4 or more carbon atoms, more preferably 8 or more carbon atoms. The above carbon number ensures a sufficiently large interlayer distance of clay minerals in consideration of the size of sublimable dye molecules or ions transferred from the ink ribbon, and
This was chosen from the viewpoint of realizing reversible ion exchange bonds.

Although all the side chains of the four trees do not necessarily have to be the same, if they are the same, the distance between the eyebrows can be particularly increased due to the steric effect. Note that the type of counter ion accompanying the exchangeable organic cation is not particularly limited.

By the way, when exchanging exchangeable cations existing between the layers of clay minerals such as montmorillonite with the above-mentioned exchangeable organic cations, generally the clay mineral is swollen in water to expand the distance between the eyebrows, and the exchangeability is increased. Clay tfL'I! can be prepared by adding a solution or dispersion containing organic cations or by pre-protonation treatment. A method is adopted in which the exchangeable cations existing between the layers of 71 are replaced with protons, and then the protons are dispersed in a solution containing exchangeable organic cations.

However, when using exchangeable organic cations that have long side chains, are highly hydrophobic, and have relatively large ionic diameters, they swell in water and create a hydrophilic environment between the layers of clay minerals. It is extremely difficult to perform ion exchange bonding. In such cases, place a dispersion of clay minerals in an organic solvent containing the desired exchangeable organic cations on the cathode side, and use an organic solvent containing only exchangeable organic cations without clay minerals. When electrolyzed on the anode side,
Ion exchange bonding can be efficiently performed on the cathode side.

Note that the quantitative range of organic cations that are ion-exchange bonded between the eyebrows of clay minerals is not particularly limited; the upper limit is the exchangeable capacity, and the lower limit is the quaternary ammonium perchlorate and perchlorate, which will be described later. The amount may be appropriately set in consideration of the amount that provides a distance between the eyebrows sufficient to enable intercalation of 4-phosphonium or sublimable dye.

In the present invention, quaternary ammonium perchlorate or quaternary phosphonium perchlorate is further retained as an intercalant in the glabella of the clay mineral whose interlayer distance has been expanded by the exchangeable organic cations as described above. In this specification, these compounds will be collectively referred to as organic perchlorates. The above-mentioned organic perchlorate is expected to maintain the structure of the clay mineral with an expanded glabellar distance by supplementing the action of the exchangeable organic cations that have already been ion-exchange bonded, and at the same time, it is expected to have a sensitizing effect due to its decomposition exothermic reaction. It is used as The cationic acid component of the organic perchlorate is an alkyl group or aryl group in which at least three of its four side chains have 4 or more carbon atoms, more preferably 8 or more carbon atoms, as in the organic cation described above. Preferably, it is based on
All four side chains do not necessarily have to be identical; furthermore, one of the side chains may be another large organic group.

In other words, it may be a compound that has a somewhat large molecular structure with the terminal end having a perchlorate structure.

In order to intercalate such an organic perchlorate into the eyebrows of a clay mineral whose interlayer distance has been expanded in advance, the clay mineral is swollen in a solution in which the organic perchlorate is dissolved in a good solvent. In this state, a large excess of a poor solvent for organic perchlorate is added. The amount of poor solvent added at this time is
The amount is sufficient to significantly bias the distribution of organic perchlorate between the glabella and liquid phase of the clay mineral. This results in
Organic perchlorates can be intercalated into the interlayers of clay minerals to prepare clay mineral complexes.

The image forming material for sublimation transfer of the present invention is obtained by holding the clay mineral composite obtained as described above on a substrate by an appropriate method. The method of holding the material on the substrate can be roughly divided into paper making method and coating method.

The paper making method is a method in which the clay mineral complex is incorporated into the fiber structure of paper. Specifically, paper is made from a pulp suspension slurry to which a clay mineral complex is added. here,
The amount of clay FL material added is 10 to 1 of the weight of pulp.
It is desirable to set it to about 00%. If the clay mineral complex is too small, the desired fixing effect and sensitizing effect cannot be obtained, and if it is too large, it becomes difficult to handle as paper.

The suspension slurry contains a sizing agent for imparting resistance to penetration by liquids (particularly water), a binder resin for preventing the clay mineral complex from falling off, etc., in an amount ranging from 0.01 to 0.01 to the weight of the clay mineral. It may be added in a range of about 10%. Alternatively, various additives used in normal papermaking processes may be included as appropriate. The thickness of the obtained paper is preferably about several tens to several hundred micrometers, taking into account ease of handling, visibility of the formed image, thermal conductivity, and the like. Calendar treatment or the like may be performed as necessary to improve surface properties.

One coating method is a method in which a coating solution containing a clay mineral complex is impregnated or applied onto a suitable substrate such as natural paper, synthetic paper, or plastic film, and then dried. The above-mentioned coating liquid is made by dispersing a clay mineral composite in a suitable solvent together with additives such as a binder. As the binder, it is necessary to select a material that has excellent releasability from the ink ribbon, and the amount used is preferably about 0.1 to 2 times the weight of the clay mineral composite. may contain additives such as a dispersant, if necessary.

[Effect]

The synthesis process of the clay mineral composite used in the present invention and the fixing mechanism of the sublimable dye will be explained with reference to FIG.

The above-mentioned clay mineral complex is composed of exchangeable cations originally existing in the interlayer part (la) of the clay mineral (1) having a layered structure, as conceptually shown in [state E] in Figure 1. (2)
At least a portion of the organic perchlorate (4) is exchanged with the exchangeable organic cation (3), and the organic perchlorate (4) is retained as an intercalate. The above-mentioned exchangeable cation (3) is, for example, an alkali metal ion such as sodium ion in natural montmorillonite, but when it undergoes protonation treatment, at least a part of it becomes proton H.
It has been exchanged with ゛. Also, in this figure, quaternary ammonium ions are illustrated as the cation moieties of the exchangeable organic cation (3) and the organic perchlorate (4), but the quaternary ammonium ion is
It is thought that a similar structure is obtained when phosphonium ions are used.

Such a clay mineral composite is synthesized as follows.

The starting material is a clay mineral (1) having exchangeable cations (2) in the interlayer region (1a), as shown in [state A] in FIG.

When the above-mentioned clay mineral (1) is protonated in a swollen state in water, as shown in [state B] in Fig. 1, the above-mentioned exchangeable cation (2) is present in the interlayer region (la). Instead, protons H are taken in, and the distance between the eyebrows also expands.

This protonation treatment not only removes impurities to increase cation exchange capacity, but also removes metal ions (especially iron ions) that interfere with the color development of sublimable dyes that are later incorporated into the interlayer (la). It also has the effect of

Next, when the clay mineral (1) is dispersed in a solvent capable of dissolving the desired exchangeable organic cation (3), and the exchangeable organic cation (3) is added, as shown in FIG. Condition LQ
Ion exchange as shown in C) occurs, and at least a portion of the protons H' are replaced by exchangeable organic cations (3). At this time, the interlayer part (la) of the clay mineral is
The four long side chains of the exchangeable organic cation (3) further expand the interlayer distance and change the environment to be hydrophobic.

Next, the above clay mineral (1) is mixed with the desired organic perchlorate (4
)including? 8 Swell in liquid. The above organic perchlorate (
Since 4) is a highly hydrophobic compound, a low polar solvent such as acetone is used as the above solution. At this stage, organic perchlorate (4
) intercalation does not occur.

However, if water is added in large excess as a poor solvent (polar solvent here) for the organic perchlorate (4), the highly hydrophobic organic perchlorate (4) continues to exist in the liquid phase. This makes it difficult for the particles to penetrate into the highly hydrophobic interlayer region (la). As a result, as shown in (state E) in FIG. 1, a clay i12.'!yJ complex is obtained in which the organic perchlorate (4) is incorporated as an intercalant into the interlayer part (1a). This clay mineral complex is nearly white, reflecting the color of the original clay mineral.

This clay mineral composite is mixed and integrated into a substrate by a method such as paper making or impregnation, or an image forming material is formed by a method such as forming a dye-receiving layer by coating, and this is brought into contact with an ink ribbon. When thermal energy is applied locally from the back side of the ink ribbon using a thermal head or the like, the sublimable dye sublimes from the ink ribbon at the heated portion and transfers to the image forming material side.

The sublimable dyes commonly used for ink ribbons are disperse dyes that are poorly soluble in water, and most of them are basic dyes that have a structure of primary, secondary, and tertiary amines in the molecule. be. On the other hand, the interlayer part (l) of clay mineral (1)
a) has increased hydrophobicity, and at the same time, the exchangeable cation (3), such as proton H or alkali metal ion, which remains without being completely exchanged by the exchangeable organic cation (3).
2), and has many acid sites due to surface silanol groups, etc. Therefore, it is easily understood that when the sublimable dye (5) transferred from the ink ribbon enters the interlayer part (1a), it is adsorbed to the acid sites and stably retained. Alternatively, as shown in (state F) in FIG. 1, when hydrogen chloride (and carbon dioxide) is produced as a by-product by thermal decomposition of the organic perchlorate (4), the sublimable dye (5) It is thought that by forming a hydrochloride, a part of its molecular structure changes to quaternary ammonium ions, which are more firmly adsorbed to the interlayer region (la) in the form of dye ions (5a). The exchangeable organic cations (3) already held in the interlayer part (1a) are released from the interlayer part (La) according to the amount of exchanged dye ions (5a).

In addition, in FIG. 1, for convenience, the cations released upon adsorption of the dye ions (5a) are expressed as exchangeable organic cations (3).
However, this may be considered to be a cation moiety derived from organic perchlorate (4).

In this way, sublimable dye (5) or dye ion (5a
) The colored clay mineral composite incorporating the sublimable dye (5) exhibits a color tone corresponding to the type of the sublimable dye (5) as a whole, and exhibits the behavior of a pigment. This colored clay mineral composite protects the dye within the interlayer (LA) without directly exposing it to the external environment, so it has excellent weather resistance, moisture resistance, chemical resistance, and heat resistance, and does not easily fade. Never.

The fixing mechanism of the sublimable dye (5) has been explained above, but another important feature of the present invention is the organic perchlorate (
This is the sensitizing effect caused by 4). The above organic perchlorate (4)
has the property of absorbing thermal energy applied from a thermal head or the like and decomposing and generating heat. At this time, once a small amount of thermal energy is absorbed at the beginning of heating and the decomposition of the organic perchlorate (4) starts, the exothermic reaction of decomposition proceeds in a chain reaction using the heat of decomposition. This means that the sensitivity of the image forming material has been substantially improved.In the past, it was attempted to improve sensitivity by selecting dyes with extremely high sublimation properties, which avoided problems such as a decrease in fixability. However, according to the present invention, such a problem does not occur.

Furthermore, an additional effect of using the perchlorate (4) is that the sublimable dye (5) or dye ions (5a) can easily diffuse in the interlayer region (la). There are various types of organic perchlorates (4), ranging from those that are liquid at room temperature to those with melting points around 300°C, but in any case, they melt at relatively low temperatures, so
The interlayer part (la) that maintains this becomes appropriate fluidity when heated. This means that if we consider the mechanism in which the sublimable dye transferred from the ink ribbon diffuses within the interlayer area (la) and reaches the acid site and is fixed, the dyeing dye 4 adsorption capacity of the clay mineral (1) can be effectively This is extremely advantageous in increasing the diffusion rate and improving fixing properties.

The image forming material for sublimation transfer of the present invention holds such a clay mineral composite integrally with a substrate, and can utilize the fixing mechanism and sensitizing mechanism of the clay mineral composite as they are. .

[Example] Hereinafter, preferred examples of the present invention will be described based on experimental results.

In this example, montmorillonite was used as the clay mineral, tetra-n-decylammonium ion was used as the organic cation, and
This is an example of photographic paper in which a clay mineral complex is synthesized using tetra-n-decylammonium perchlorate as an organic perchlorate, and this clay mineral complex is further coated on paper together with a rubber-based binder. .

The synthesis of clay mineral complexes was carried out according to the following procedure.

First, 20 g of commercially available montmorillonite (manufactured by Kunigofu Kogyo Co., Ltd., trade name Nipia F) was dispersed in IF water, swollen, and diluted with 35% hydrochloric acid solution while stirring. 8 liquid 2.12g (
20 mg equivalent) was gradually added dropwise to perform protonation treatment. At this time, the dispersion liquid increased in viscosity, and the alkali metal ions originally present in the interlayers of montmorillonite were replaced by protons. According to X-ray diffraction, the (001) plane spacing, or interlayer distance, of this protonated clay mineral is 13.6.
The distance between the eyebrows of early montmorillonites (9,7
8 people).

Next, 800 mf of ethanol was added to the above dispersion, and 13.2 g of tetra-n-decylammonium bromide was added.
(20 mg equivalent) dissolved in 200 mj2 of ethanol was added dropwise, resulting in agglomeration and precipitation of particles. 10 g of sodium hydroxide was added to this dispersion and left at room temperature for 2 days. Thereafter, the above dispersion By filtering the precipitate from the solution and washing with a sufficient amount of ethanol, the Mu tetra-
n-decylammonium ion was removed. Next, wash with enough water until the washing liquid becomes neutral.
Sodium hydroxide was removed. The above precipitate was dried at 60°C under reduced pressure to obtain an off-white powder. This gray-white powder has at least a portion of the protons in the interlayer region tetra-n-
It is a modified clay mineral substituted with decyl ammonium ions. The (001) plane spacing of this modified clay mineral is 22.6
The number had increased to three.

Next, three parts of the above modified clay mineral were added to a solution of 1 part by weight of tetra-n-decylammonium perchlorate dissolved in 100 parts by weight of acetone, which is a good solvent, and subjected to ultrasonic dispersion treatment for 10 minutes. went. When 1000 parts by weight of water, which is a poor solvent for the organic perchlorate, was added to this dispersion, the powder coagulated and precipitated. The precipitate was filtered and dried at 50°C under reduced pressure to obtain a slightly yellowish white powder.

This white powder is a clay mineral complex in which tetra-n-decylammonium perchlorate is intercalated in the interlayer parts.

Using the clay mineral complex obtained as above,
Next, I made photographic paper.

That is, first, 12 g of the dried clay mineral complex was collected in a beaker, 100 g of an aqueous solution containing 0.3% by weight of sodium alginate was added as a dispersant, and the mixture was subjected to dispersion treatment for several hours using a high-power ultrasonic dispersion machine. and prepared a slurry. To this slurry, 200 g of water and 4 g of styrene-butadiene rubber latex (manufactured by Japan Synthetic Rubber Co., Ltd., trade name 0863) were further added to prepare a coating liquid.

This coating solution was applied to neutral paper having a thickness of about 100 μm using a wire bar while impregnating it, followed by drying with hot air at 100° C. and further calendering to obtain photographic paper.

Next, an experiment was conducted to actually form an image using this photographic paper and an ink ribbon containing sublimable dye.

First, an ink layer paint for an ink ribbon was prepared according to the following composition.

Sublimation dye (manufactured by Sumitomo Chemical Co., Ltd.)

(Product name: Sumiplus Trend FB) Ethyl cellulose (manufactured by Vercules, USA, product name: N-7) Ethanol butanol 5 parts by weight 5 parts by weight 63 parts by weight 27 parts by weight The above ink layer paint was applied to one side of a 6 μm thick PET (polyethylene terephthalate) film. The film thickness when dried is 2 μm.
An ink ribbon was created by applying it using a gravure printing machine.

When the above photographic paper and ink ribbon were placed in a thermal transfer printer and an image was formed by applying 80 mJ/mm'' of thermal energy, high sensitivity was obtained.

High-quality images with high contrast ratio and resolution were formed. Furthermore, the formed image had excellent storage stability.

(Effects of the Invention) As is clear from the above description, according to the image forming material for sublimation transfer of the present invention, fixing properties can be improved without particularly improving the sublimable dye, and unlike the conventional There is no discoloration or fading during long-term storage.Furthermore, since practical image formation can be performed with less thermal energy, the image formation speed is greatly improved, and the power consumption of thermal transfer printers and the like can be reduced.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram for conceptually explaining the synthesis process of the clay mineral composite used in the present invention and the fixing mechanism of the sublimable dye. Clay mineral interlayer exchangeable cation exchangeable organic cation organic perchlorate sublimable dye dye ion patent

Claims (1)

[Claims] Quaternary ammonium ions or quaternary ammonium ions are present between the clay mineral layers.
An image forming material for sublimation transfer comprising a clay mineral composite in which phosphonium ions are bonded by ion exchange and quaternary ammonium perchlorate or quaternary phosphonium perchlorate is retained as an intercalant on a substrate.