JPH0444044A - Image formation and image forming medium - Google Patents

Abstract

PURPOSE:To easily form an image of high picture quality with an excellent contrast by putting the image forming medium where a latent image is formed and an image receiving body one over the other and heating them under a specific condition, and transferring a heat-diffusing material to the image receiving body and forming an image. CONSTITUTION:The image forming medium is constituted by forming a coloring material layer 2 which contains the heat diffusing material and a polymerizing layer 1 which contains a polymerizing compound and a polymerization initiator on a base 3. Then the polymerizing layer 1 is exposed through a proper negative mask 4 to polymerize the polymerizing compound in the polymerized layer 1, thereby forming the latent image consisting of a polymerized part 1-a and an unpolymerized part 1-b. Then the image formed medium where the latent image is formed and the image receiving layer 6 on a base body 5 are put one over the other and heated under the heating condition shown in an expression I to diffuse and transfer the heat diffusing material that the image formed medium contains to the image receiving layer 6 through the polymerized layer 1. In the expression I, Ttrans shows the temperature of the image forming medium, Tg1 the glass dislocation temperature of the unpolymerized part 1b, and Tg2 the glass dislocation temperature of the polymerized part 1g. Consequently, the excellent image which has high contrast and no fogging is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of forming an image made of a thermally diffusive material and an image forming medium used in the method.

[Prior Art] Conventional thermal recording methods mainly include a direct thermal method, a thermal transfer method, a sublimation transfer method, and the like.

The direct thermal method is a method in which a color-forming body having the property of developing color by heat is heated in a desired pattern using a thermal head or the like to form characters or images. This method has the disadvantage that the uncolored portions of the resulting image tend to develop color under the influence of heat or chemicals, resulting in poor image stability and storage stability. Furthermore, this method is difficult to colorize.

On the other hand, the thermal transfer recording method uses an ink donor sheet that is formed by coating a plastic film such as polyester with a heat-melting ink containing a dye, etc., and the donor sheet is shaped into a desired pattern using a thermal head, etc. This is a method of forming an image by heating the toner sheet to heat and melt the ink, and then transferring the ink to an adjacent image-receiving paper. In this method, multiple colors can be superimposed to form a color image. However, special equipment and a special donor sheet are required to obtain images with density gradation.

The sublimation transfer method uses an ink toner sheet formed by coating a resin film with ink containing a sublimable dye.The donor sheet is heated in a desired pattern using a thermal head, etc., and only the dye in the heated areas is applied. This is a method in which an image is formed by sublimating the liquid and transferring it to image-receiving paper or the like.

According to this sublimation transfer method, unlike the above-mentioned thermal transfer recording method, an image with density gradation can be obtained by controlling the thermal head, controlling the heat application energy, controlling the heat application time, etc. However, it is not easy to control them with high precision. In addition, in this method, the thermal head normally generates heat on and off at 1 m5ec.
The desired sublimation and concentration cannot be obtained unless heating is performed at a considerably high temperature by repeating ff. However, when heated at such high temperatures, the sublimable dye is not absorbed and the binder component in the sheet is also transferred to the image receptor, resulting in a decrease in the quality of the resulting image.

[Problems to be Solved by the Invention] An object of the present invention is to provide a method of easily forming a high-quality image with good contrast, and an image forming medium used in the method.

Another object of the present invention is to obtain a high gradation image;
Another object of the present invention is to provide an image forming method in which the gradation control and image forming process can be easily performed, and an image forming medium used in the method.

[Means for Solving the Problems] The present invention provides the following image forming methods (1), (2),
(4) and the following image forming medium (3).

(1) By site-selectively polymerizing the polymer layer of an image forming medium having a coloring material layer containing at least a heat-diffusible substance and a polymer layer containing at least a polymerizable compound and a polymerization initiator, and an unpolymerized portion, and heating the image forming medium on which the latent image is formed such that the following formula (A) is satisfied, T g +≦T trans≦Tgz − (A
) (wherein T trans represents the temperature of the image forming medium, T g + represents the glass transition temperature of the unpolymerized portion,
T g 2 indicates the glass transition temperature of the polymerized portion. ) An image characterized in that the heat-diffusible substance contained in the coloring material layer is selectively transferred to an image receptor via the polymer layer, and an image made of the heat-diffusible substance is formed on the image receptor. Formation method.

(2) Form a latent image and heat in the same manner as in method (1) above to selectively diffuse and remove the heat-diffusible substance contained in the coloring material layer through the polymer layer, and apply the heat to the image forming medium. An image forming method characterized by forming an image made of residual heat diffusible material.

(3) An image forming medium having at least a coloring material layer containing a thermally diffusive substance and a polymer layer containing at least a polymerizable compound and a polymerization initiator, wherein the polymer layer of the image forming medium is selectively polymerized. An image forming medium characterized in that, by doing so, a latent image not satisfying the following formula (B) and consisting of a polymerized portion and an unpolymerized portion can be formed.

T g 2 T g +≧30'C...(B) (4
) A latent image is formed in the same manner as in methods (1) and (2) above, and the overlapping portion or unpolymerizing portion is transferred to the transfer target depending on the difference in tackiness of the latent image, and after the transfer, The image forming medium is overlapped with the image receptor and heated to selectively transfer the heat-diffusible substance contained in the coloring material layer to the image receptor, thereby forming an image made of the heat-diffusible substance on the image receptor. An image forming method characterized by:

In addition, in the process of polymerizing the image forming medium site-selectively (in a desired pattern) in the method of the present invention, the polymerized portion is the "polymerized portion" as used in the present invention, and the unpolymerized portion is the "polymerized portion". This is the "unpolymerized part" in the present invention. The desired pattern consisting of the "polymerized part" and one unpolymerized part is the "latent image" in the present invention. Note that the polymerization also includes crosslinking. In addition, "unpolymerized area" refers not only to the case where no polymerization occurs at all, but also to the case where it is substantially unpolymerized, that is, to the extent that it does not interfere with the good diffusivity of the thermally diffusible substance (to the extent that it does not affect image formation). ) is also included. The “thermal diffusible substance” as used in the present invention is
For example, it means a heat-diffusible dye, a diffusible substance that exhibits a color by reacting with a color developer after being heat-diffused.

The method of the present invention is an image forming method that forms a latent image consisting of the polymerized portion and unpolymerized portion, and utilizes the difference in diffusibility of a heat diffusible substance caused by the latent image.

Another method is to use an image forming medium having at least a polymer layer and a coloring material layer, that is, at least two functionally separated layers. First, the influence of a latent image on the diffusivity of a thermally diffusible substance will be explained below.

Figure 4 shows the temperature of the heated ink toner sheet (Tt, , , ) and the optical density of the dye (thermally diffusible substance) diffusely transferred from the toner sheet onto the image receiving paper in the conventional sublimation transfer method. It is a figure which illustrates the relationship with (OD). Optical density (OD
) is the inherent diffusion temperature (
TdItreuse generally this T d+ t r. 6 is
The lower the molecular weight of the substance is, the lower it is, and the more polar groups attached to the substance, the higher it is), and the glass transition temperature (Tg) of the constituent components of the layer containing the dye (binder etc.) If Tg≧T a + f f u s a,
The temperature at which the dye begins to diffusely transfer onto the receiver paper is T d l
It exceeds tfuse and coincides with Tg. In addition, when T d I f u s o ≧ Tg, the temperature at which the dye starts to be diffusely transferred onto the receiving paper is T d I f u s o ≧Tg.
Matches f f u s a. That is, by heating a layer containing a dye (thermally diffusible substance), the temperature of the layer (T
(Ttrans≧Ta1ttu-, T
g) As a result, the dye (thermal diffusive substance) in the layer diffuses and is transferred to the image receptor, resulting in an image on the image receptor. In such conventional sublimation transfer systems, the binder in the ink toner sheet has negative physical properties, and the binder does not suppress the diffusivity of the dye.

Unlike such conventional methods, in the present invention,
The molecular chains of the polymer in the polymerization part suppress the diffusible substances from passing through the polymerization layer. Therefore, unless the polymerization layer is heated to a temperature below the glass transition temperature of the polymerization part and the molecular chains are not relaxed (the molecular chains are loosened by molecular vibrations caused by heat), the diffusible substances in the colorant layer cannot be absorbed in the polymerization part. It becomes possible to pass only the unpolymerized portion without passing through.

Figure 5 shows the temperature (Tt, , , ) of the heated image forming medium and the optical density of the dye (thermally diffusible substance) diffusely transferred from the medium onto the image receiving paper in method (1) of the present invention. It is a graph illustrating the relationship with (OD). In this graph, the curve (a) shows the above relationship for the portion corresponding to the polymerized portion, and the curve (b) shows the above relationship for the portion corresponding to the unpolymerized portion. Furthermore, the temperature of the image forming medium is a value measured on the surface of the heater and heat roller during transfer.

As shown by curve (a) in FIG. 5, the heat diffusive substance contained in the coloring material layer in the area adjacent to the unpolymerized part of the polymerized layer is
At a temperature corresponding to the glass transition temperature (Tg+) of the unpolymerized part, it becomes possible to diffuse into the unpolymerized part and begin to be transferred onto the image receptor. As T trans increases, molecules of the binder and polymerizable compound forming the unpolymerized portion are relaxed, and as a result, the optical density (OD) increases.

On the other hand, as shown by curve (b) in the figure, the thermally diffusive substance in the polymerized part of the polymerized layer is able to diffuse into the unpolymerized part from a temperature corresponding to the glass transition temperature (Tgz) of the polymerized part. and begins to be transferred onto the image receptor. And T t
As the rsns increases, the binder and polymer molecules forming the polymerization portion are relaxed, the diffusion transferability of the thermally diffusive substance is improved, and the optical density (OD) is increased.

From the above relationship between curves (a) and (b), T
When trans is lower than T g + (B in the same figure)
The thermally diffusive substance does not diffuse or pass through any of the polymerized portions and unpolymerized portions of the polymerized layer, and is not transferred onto the image receptor, so that no image is formed.

On the other hand, when T trans is higher than T g 2 (region C in the figure), the optical density (OD) of the thermally diffusive material transferred from the unpolymerized portion of the polymerized layer onto the image receptor is sufficient. However, since transfer also occurs from the overlapping portion, image fogging is added, which is not desirable.

In the image forming method of the present invention, T trRns corresponds to region A in the figure, that is, T g +≦T trans
The region is ≦T g 2. As a result, a good image with high contrast and no fogging can be obtained on the image receptor.

In addition, unlike the conventional sublimation transfer method (using a thermal head), the method of the present invention does not require high-temperature heating, so other components contained in the medium (binder, polymerizable compound, etc.) are melted. It is possible to prevent the image from being transferred to the image receptor by sublimation, and it is possible to obtain an image with better image quality.

Furthermore, setting T trans to region D in the same figure means that
This is preferable because the optical density of the image obtained on the image receptor is sufficiently high.

Note that to form a color image, yellow macenta,
It is sufficient to form donor sheets in three or four colors of cyan and black, transfer them sequentially, and overlap them.

In addition, when adding gradation to an image using the method of the present invention, the fifth
As shown in the curve (c) shown in the figure, the amount of heat-diffusive material passing through can be changed by changing the degree of polymerization of the polymer layer. In this method, in order to obtain a high gradation image, the Tg of the latent image is
In addition to considering two types of T g 1 and T g 2, 1 g 1
It is sufficient that the gradation Tg exists within the range of ˜T g 2. That is, for example, when the latent image forming step of the method of the present invention is carried out by photopolymerization by patterned exposure through a mask, the mask is not a mask consisting only of a transparent part and a non-transparent part, but a photographic negative. A gradation mask such as a film that also has a semi-transparent part may be used. When analog exposure is performed using such a mask, gradation polymerization is performed according to the mask pattern, and a latent image having a gradation Tg corresponding to the mask pattern can be formed. If the medium with the latent image is heated to a certain temperature, the gradation T
An image with high gradation corresponding to g can be easily obtained. In addition, in the case of obtaining such a gradation image, T g 2 in the above formula (A) means the highest glass transition point among the polymerized parts.

As mentioned above, the method of the present invention (]), (2), (4
), the degree of polymerization of the polymerizable compound contained in the medium (
It is possible to obtain an image with high gradation by controlling the degree of crosslinking and the degree of crosslinking, and this method is much simpler than the conventional sublimation transfer method described above.

Further, in the image forming method of the present invention, since an image forming medium having a functionally separated polymer layer and a coloring material layer is used, the polymer layer can be used for multiple colors such as yellow macenta and cyan. The structure is simple, and in the case of photopolymerization, the negative effect of absorbing the polymerization initiation light of the coloring material is eliminated, and the polymerization rate is increased.

The above is an explanation of the method (2) of the present invention in which image-receiving paper is overlapped with a medium and heated. The method (4) of the present invention, in which the thermal diffusive substance is transferred after separating the particles, also exhibits the same effect as described above.

Hereinafter, the image forming method of the present invention (1), (2), (4)
) will be explained in detail using the drawings.

First, as illustrated in FIG. 1, an image is formed by forming a coloring material layer 2 containing a heat-diffusible substance and a polymerization layer 1 containing a polymerizable compound and a polymerization initiator on a support 3. Prepare the medium. Those components will be explained in detail later.

Next, as illustrated in FIG.
, the polymerization layer 1 is exposed to light having an absorption wavelength of the polymerization initiator contained in the polymerization layer 1, and the polymerizable compound in the polymerization layer 1 is polymerized, and polymerization is performed according to the pattern of the negative mask 4. A latent image consisting of a portion 1-a and an unpolymerized portion 1b is formed.

Note that the process shown in FIG. 1 is an example, and the present invention is not limited thereto. In other words, any polymerization method may be used as long as it can obtain portions with different desired Tg. For example, analog exposure, digital exposure, etc. other than mask exposure as exemplified above may be used. Further, instead of photopolymerization, thermal polymerization using a thermal head or the like may be used. Furthermore, the polymerization rate can be increased by simultaneously performing exposure and heating. When heating is performed, it is preferable to heat the colorant layer so that it remains at a temperature lower than the diffusion temperature of the thermally diffusive substance. Further, even in the case of obtaining a gradation image as described above, the present invention is not limited to any polymerization method as long as it can obtain a gradation Tg.

In addition, in this process, forming a latent image in which the difference between T g 2 of the polymerized portion 1-a and T g r of the unpolymerized portion 1a is greater than 30°C is a key to good contrast. This is preferable in terms of obtaining images. A medium capable of forming such a latent image is the image forming medium (3) of the present invention. However, the methods (1) and (2) of the present invention are not limited to forming the medium (3), and the method (1) and (2) of the present invention is not limited to forming the medium (3), and the method (1) and (2) of the present invention is not limited to forming the medium (3).
A method may be employed in which a latent image smaller than 0.degree. C. is formed. Further, it is preferable that the value of T g + is lower, since the diffusive substance can be diffused better, the optical density on the image receptor can be increased, or removal by sublimation can be performed better. However, T
If the value of g1 is too low, it is undesirable because the part becomes liquid and becomes difficult to handle.

In addition, when performing exposure in this process, the light source may be, for example, sunlight, tungsten lamp, mercury lamp, halogen lamp, xenon lamp, fluorescent lamp, LE
Examples include D, laser, electron beam, and X-ray.

Examples of exposure methods that do not use a negative mask include liquid crystal shutter arrays, CRTs, and optical fiber tubes. In this case, preferably 250 to 700 nm, more preferably 300 to 50 nm
Exposure is performed with light having a wavelength of 0 nm and an energy of up to 500 mJ/cm2.

Next, in the method (1) of the present invention, as shown in FIG. 2, the image forming medium on which such an image has been formed and the image receiving layer 6 on the substrate 5 are overlapped and heated. According to
The thermally diffusive substance contained in the image forming medium is diffusely transferred to the image receiving layer 6 through the polymeric layer 1 .

The image-receiving layer 6 in this process is not particularly limited as long as the diffusible substance can be diffused and transferred well and a good image can be formed, such as polyester resin, polycarbonate resin, polyvinyl acetate resin, polyurethane resin, etc. Resin, polyamide]・Resin, polycaprolactone resin,
Various materials such as polyvinyl chloride resin can be used.

After performing diffusion transfer in the manner described above, by peeling off the medium, an image made of a diffusive substance as shown in FIG. 3 can be obtained in the image-receiving layer 6.

On the other hand, in method (2) of the present invention, the above-mentioned image receptor is not used, and the diffusible substance is diffused and removed by heating the medium, and an image made of the diffusible substance remaining on the medium is formed.

Further, in the method (4) of the present invention, as shown in FIG. 6, after forming a latent image consisting of an overlapping portion 1-a and an unoverlapping portion]-b, the transfer target 7 is brought into contact with each other, The unpolymerized portion is peeled off by utilizing the difference in adhesiveness between the polymerized portion and the unpolymerized portion. Note that the above-mentioned gradation Tg may be formed in the overlapping portion 1-a. Thereafter, similarly to the method (1) of the present invention, the unpolymerized portion]-
The heat diffusive substance is diffused and transferred from the coloring material layer in the area where b is removed to the image receptor. According to the method (4) of the present invention, the transfer rate and contrast of the thermally diffusive substance are further improved, and sufficient image density can be obtained even if the concentration of the thermally diffusive substance in the coloring material layer is lowered. . Note that the transfer object 7 may be bonded together before image formation or at the beginning of image formation, or may be bonded together in the middle of the image formation process. Further, in the method (4) of the present invention, it is preferable to peel off and remove the unpolymerized portion [-b] as described above, but it is not limited thereto, and a mode where the polymerized portion ia is peeled off is also possible.

In the method of the present invention (+1. (2)), the heating temperature is not particularly limited as long as it satisfies the relationship of formula (A) above, and the optimal heating temperature is , although it varies depending on various conditions, is preferably 70 to 70.
The temperature is 250°C, preferably 80 to 160°C. Further, as the heating means, a hot plate, a heat roll, a thermal head, etc. can be used. Other methods that can be used include a method in which a heating element is provided on the support and the heating element is heated by supplying electricity to the support, and a method in which heating is performed using an infrared light source or laser light irradiation. Also in method (4) of the present invention, suitable heating temperatures and heating means are the same as described above.

Next, the image forming medium (before latent image formation) used in the method of the present invention will be described in detail.

Thermal diffusible substances contained in the medium used in the method of the present invention include, for example, 1,000 azo dyes, thiazole azo dyes, anthraquinone dyes, triallylmethane dyes, rhodamine dyes,
Examples include naphthol dyes, triarylmethane dyes, fluoran dyes, and fucrite dyes.

In general, the smaller the molecular weight of a thermally diffusible substance, the greater its thermal diffusivity; for example, substances with many polar groups such as carboxyl groups, amino groups, hydroxyl groups, nitro groups, and sulfone groups have low thermal diffusivity. . Therefore, depending on the degree of polymerization, crosslinking density, heating conditions, etc. in the medium of the present invention,
A substance having desired thermal diffusivity may be appropriately selected based on molecular weight and polar group. Furthermore, it is desirable to appropriately increase the content of the thermally diffusive substance in that the image on the image receptor can have a high density. From this point of view, the content of the thermally diffusive substance is desirably 2.5 to 50% by weight, preferably 5 to 20% by weight.

In addition, when using a substance that exhibits a color by reacting with a color developer in an image receptor after being thermally diffused as a thermally diffusive substance, zinc oxide, calcium sulfate, noholac type phenol, etc. can be used as the color developer. resin, 35-dimethyl-tert-
Zinc butylsalicylate and the like can be used.

As the polymerizable compound contained in the medium used in the method of the present invention, compounds having at least one reactive vinyl group in the molecule can be used, such as reactive vinyl group-containing monomers, reactive vinyl group-containing oricomers, etc. - and reactive vinyl group-containing polymers can be used.

The reactive vinyl groups of these compounds include styrene vinyl groups, acrylic acid vinyl groups, vinyl methacrylate groups, allyl vinyl groups, vinyl ether, and ester vinyl groups such as vinyl acetate. Examples include substituted or unsubstituted vinyl groups.

Specific examples of polymerizable compounds satisfying such conditions are as follows.

For example, styrene, methylstyrene, chlorstyrene,
Bromostyrene, methoxystyrene, dimethylaminostyrene, cyanostyrene, dirostyrene, hydroxystyrene, aminostyrene, carboxystyrene, acrylic acid, methyl acrylate, ethyl acrylate, cyclohexyl acrylate, acrylamide, methacrylic acid, methacrylic methyl acid, butyl methacrylate, propyl methacrylate, butyl methacrylate, phenyl methacrylate, cyclohexyl methacrylate, vinylpyridine,
N-vinylpyrrolidone, N-vinylimidazole 1≧-
Vinylimidazole, N-methyl-2-vinylimidazole, propyl vinyl ether, butyl vinyl ether,
Monovalent monomers such as inbutyl vinyl ether, β-chloroethyl vinyl ether, phenyl vinyl ether, p-methylphenyl vinyl ether, p-chlorophenyl vinyl ether; for example, divinylbenzene, distyryl oxalate, distyryl malonate, distyryl succinate, Distyryl glutarate, distyryl adipate, distyryl maleate, distyryl fumarate, β,β-distyryl dimethylglutarate 1≧-distyryl bromoglutarate, α,a゛-distyryl dichloroglutarate, distyryl terephthalate, distyryl oxalate ethyl acrylate), oxalic acid di(methyl ethyl acrylate), malonic acid di(ethyl acrylate), malonic acid di(methyl ethyl acrylate), succinic acid di(ethyl acrylate), glutaric acid di(ethyl acrylate), adipic acid di(ethyl acrylate) (ethyl acrylate), maleic acid di(diethyl acrylate), fumaric acid di(ethyl acrylate),
β,β-dimethylglutarate di(ethyl acrylate)
, ethylene diacrylamide, propylene diacrylamide, 1,4-phenylene diacrylamide, 1,4-
Phenylene bis(oxyethyl acrylate), 1.4
-Phenylenebis(oxymethylethyl acrylate)
, 1.4-bis(acryloyloxyethoxy)cyclohexane, 1.4-bis(acryloyloxymethylethoxy)cyclohexane, 1.4-bis(acryloyloxyethoxycarbamoyl)benzene, 1.4-bis(acryloyloxymethylethoxycarbamoyl) ) Benzene, 1.4 bis(acryloyloxyethoxycarhamoyl)cyclohexane, bis(acryloyloxyethoxycarhamoylcyclohexyl)methane, di(ethyl methacrylate) oxalate, di(methyl ethyl methacrylate) oxalate, di(methyl ethyl methacrylate) malonic acid ethyl methacrylate), malonic acid di(methyl ethyl methacrylate),
Di(ethyl methacrylate) succinate, di(methyl ethyl methacrylate) succinate, di(ethyl methacrylate) glutarate, di(ethyl methacrylate) adipic acid, di(ethyl methacrylate) maleate, di(ethyl methacrylate) fumarate, di(ethyl methacrylate) fumarate. Acid (methyl ethyl methacrylate), β.

β'-Dimethylglutarate (ethyl methacrylate)
, 1,4-phenylenebis(oxyethyl acrylate), 1,4-bis(methacryloyloxyethoxy)cyclohexane acryloyloxyethoxyethyl vinyl ether; for example, pentaerythritol triacrylate, pentaerythritol trimethacrylate, pentaerythritol trimethacrylate, Erythritol tri(hydroxystyrene), cyanuric acid triacrylate, cyanuric acid trimethacrylate, 1,1. ．． 1-trimethylolpropane triacrylate, 1.11-trimethylolpropane trimethacrylate, cyanuric acid tri(ethyl acrylate), 1,1. ．． 1-trimethylolpropane tri(ethyl acrylate), cyanuric acid 1-tri(ethyl vinyl ether), I, 1.1-Trimethylolpropane and 3 times the mole of toluene diisocyanate reaction product and hydroxyethyl acrylate condensate , 1.1.1
~Trivalent monomers such as a condensate of p-hydroxystyrene and a reaction product of trimethylolpropane and 3 times the mole of hexane diisocyanate; for example, a tetravalent monomer such as ethylenetetraacrylamide and propylenetetraacrylamide Further examples include polymerizable polymer precursors in which a reactive vinyl group is left at the end of the oligomer or polymer, and polymerizable compounds in which a reactive vinyl group is attached to the side chain of the oligomer or polymer.

Note that, as described above, two or more of these polymerizable compounds may be used.

The polymerization initiator contained in the medium used in the method of the present invention is a photopolymerization initiator and/or a thermal polymerization initiator.

As the thermal polymerization initiator, known initiators can be used, such as azo initiators and peroxide initiators. An azo initiator is an organic compound having at least one nitrogen-nitrogen double bond in its molecule, such as azobisisobutyronitrile, azobiscyclohexanecarbonitrile, azobismethylphenethylcarbonitrile,
Azobis5ec-amylontrile, azobisphenylethane, azobiscyclohexylpropyronitrile, azobismethylchloroethane, trityl azobenzene, phenylazoisobutyronitrile, 9-(p-nitrophenyl/)-9-phenylfluorene, etc. can be mentioned. The peroxide initiator includes almost all organic compounds having at least one oxygen-oxygen bond in the molecule. For example, methyl ethyl ketone peroxide, cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide, methylcyclohexanone peroxide, acetylacetone peroxide, 1,1'-bis(tert-butylperoxy)-3,3,5 -trimethylcyclohexane, 1,1'-bis(tert-butylperoxy)cyclohexane, n-butyl-44
-bis(tert-butylperoxy)parerate 1
≧． 2'-bis(tert-butylperoxy)butane, tert-butyl hydroperoxide, cumene hydroperoxide, diisopropyl pembene hydroperoxide, para-menthane hydroperoxide, 25-dimethylhexane-2, - Siberite bro-oxide, 1,1,3.3-tetramethylbutylhytroperoxide di-tert-butyl peroxide, tert-butyl tamyl peroxide, dicumyl peroxide, α, α゛-bis(tert-butyl peroxyisopropyl) benzene 1≧. 5-dimethyl25-di(tert-butylperoxy)hexane 1≧. 5-dimethyl-2,5-di(tertiarybutylperoxy)hexyne-3, acetyl peroxide, isobutyryl peroxide, octanoyl peroxide, decanoyl peroxide, lauroyl peroxide, 3.5.5-trimethyl Hexanoyl peroxide, cohelic acid peroxide, benzoyl peroxide 1≧4
-dichlorobenzoyl peroxide, m-toluoyl peroxide, diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxycarbonate, di-2-ethylhexyl peroxydicarbonate, di-2-ethoxyethyl peroxydicarbonate , dimethoxyisopropyl peroxycarbonate, cy(3-
Methyl-3-methoxybutyl) peroxydicarbonate, t-butyl peroxyacetate, t-butyl peroxyisobutyrate, t-butyl peroxyvivalate, t-butyl peroxyneodecanoate, t-butyl peroxy Oxyoctanoate, tert-butyl peroxy-3,
5゜5-trimethylhexanoate, tert-butyl peroxylaurate, tert-butyl peroxybenzoate, di-tert-butyl peroxy isophthalate 1≧. Examples include 5-dimethyl-25-di(benzoylperoxy)hexane, tertiary butyl peroxymaleic acid, tertiary peroxyisopropyl carbonate, but the present invention is not limited to these. Other known thermal polymerization initiators can also be used.

Examples of the photopolymerization initiator include carbonyl compounds, inorganic compounds, halogen compounds, redox photopolymerization initiators, and the like.

Specifically, carbonyl compounds include diketones such as benzyl, 4,4'-dimethoxypencyl, diacetyl, and camphorquinone; benzophenones such as 4,4'-diethylaminobenzophenone and 4,4'-dimethoxybenzophenone; For example, acetophenones such as acetophenone and 4-methoxyacetophenone; For example, l\nzoin alkyl ethers: For example, 2-cyclothioxanthone 1≧-5-diethylthioxanthone, thioxanthone-3-carboxylic acid-β-methoxyethyl ester, etc.; Dioxanthone, chalcone having a dialkylamino group, and styryl ketone: Coumarins such as 3.3' carbonylbis(7-medoxycoumarin) and 3°3°-carbonylbis(7-dinithylaminocoumarin). can give.

Examples of useful compounds include dibenzothiazolyl sulfite,
Examples include disulfides such as decylphenyl sulfite.

Examples of halogen compounds include carbon tetrabromide, quinolinesulfonyl chloride, and 5-
Examples include 1-riazine.

Redox-based photopolymerization initiators include those used in combination with trivalent iron ion compounds (e.g. ferric ammonium citrate) and peroxide, and those used in combination with photoreducing substances such as rifoflavin and methylene blue and triethanolamine. , and those using a combination of reducing agents such as ascorbic acid.

Moreover, a more efficient photopolymerization reaction can be obtained by combining one or more of the photopolymerization initiators described above.

Examples of such combinations of photopolymerization initiators include chalcone and styryl styryl ketones having a dialkylamino group, combinations of coumarins and s-triazines having a triheromethyl group, and camphorquinone.

These polymerization initiators may also be used in combination of two or more thereof or in combination with the above-mentioned compounds.

In the method of the present invention described above, it is preferable to use the image forming medium (3) of the present invention from the viewpoint of improving contrast and density gradation. As mentioned above, the image forming medium (3) of the present invention is an image forming medium having at least a coloring material layer containing a heat diffusible substance and a polymer layer containing at least a polymerizable compound and a polymerization initiator, The image forming medium is characterized in that by site-selectively polymerizing the polymer layer of the image forming medium, a latent image consisting of a polymerized portion and an unpolymerized portion satisfying the following formula (B) can be formed.

1g2-Tgl≧30°C (B) The image forming medium (3) of the present invention has a temperature of 250 to 700° C. selectively.
It is desirable that polymerized portions and unpolymerized portions satisfying the above formula (B) can be formed by exposure to light in the nm wavelength range or by heating. When producing the image forming medium (3) of the present invention, the above formula (B
) can be obtained by appropriately selecting a polymerizable compound that mainly contains the following. In addition, in (B) above,
Furthermore, it is preferable that Tgz Tg+≧50'C. Further, it is preferable that the value of T g + is lower, since the diffusive substance can be diffused better, the optical density on the image receptor can be increased, or removal by sublimation can be performed better. However, T g
If the value of + is too low, the part becomes liquid and becomes difficult to handle, which is undesirable. Therefore, the value of Tgl is preferably about 30 to 80°C. On the other hand, T g 2
The value of is preferably about 100 to 220°C.

When forming the medium of the present invention into a desired layer, the above-mentioned essential components are dissolved in a solvent together with an appropriately used binder, and the solution is sequentially coated and dried on a support such as metal, plastic, or paper, or the binder itself is If the strength can be maintained, the above-mentioned essential components can be contained in a film or sheet-like product formed from a binder without using a support. Furthermore, when the medium contains a binder, the Tg of the binder may affect the Tg of the latent image (especially when the Tg of the binder is low).
It is necessary to take this point into consideration and make an appropriate selection.

In order to obtain the image forming medium (3) of the present invention capable of forming Tgl and Tg2 as described above, it is preferable to appropriately select and contain a polymerizable compound and the like as described above.

Furthermore, it is also preferable to contain in combination a polymerizable compound that is polymerized and/or crosslinked and hardened by polymerization with a binder used for maintaining the layer shape. In particular, binders with a high glass transition temperature and liquid polymerizable compounds can be polymerized to form a polymerization part with a high Tg, and polyfunctional polymerizable compounds can be polymerized to increase the crosslink density. It is also preferable to combine materials that yield a highly cured product. Further, it is preferable that the coloring material layer is formed using a binder with a low Tg so as to easily release the contained thermal diffusive substance, and the polymer layer is formed using a binder with a high Tg as described above and a polymerizable compound. A combination of these is preferred.

Suitable binders for use in the present invention can be selected from a wide variety of resins.

Specifically, cellulose esters such as nitrocellulose, cellulose phosphate, cellulose sulfate, cellulose acetate, cellulose propionate, cellulose acetate, cellulose myristate, cellulose palmitate, cellulose acetate/propionate, cellulose acetate/butyrate:
For example, cellulose ethers such as methylcellulose, ethylcellulose, propylcellulose, butylcellulose; for example, polystyrene, polyvinyl chloride, polyvinyl acetate, polyvinyl butyral, polyvinyl acecool,
Vinyl resins such as polyvinyl alcohol and polyvinylpyrrolidone; for example, styrene-butadiene copolymers,
Copolymer resins such as styrene-acrylonitrile copolymer, styrene-butadiene acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer; for example, polymethyl methacrylate, polymethyl acrylate, polybutyl acrylate, polyacrylic acid, polymethacrylic acid, polyacrylamide, poly Acrylic resins such as acrylonitrile; polyesters such as polyethylene terephthalate; such as poly(4,4-isopropylidene, diphenylene-2-1,4-cyclohexylene dimethylene carbonate), poly(ethylenedioxy-
3,3°-phenylene thiocarbonate), poly(4,
4'-isopropylidene diphenylene carbonate coaterefcrate), poly(4,4'-isopropylidene diphenylene carbonate), poly(4,4'
-5ec-butylidene diphenylene carbonate),
Polyarylate resins such as poly(4°4°-isopropylidene diphenylene carbonate block-oxyethylene); Polyamides: Polyimides; Epoxy resins: Phenolic resins; For example, polyethylene, polypropylene, chlorinated polyethylene, etc. Examples include polyolefins; and natural polymers such as gelatin.

Note that the binder is not an essential component in the medium of the present invention. When the film properties, dispersibility, and sensitivity of each layer of the medium, especially the relationship expressed by the above formula (B), are sufficient, it is not necessary to contain it.

In addition, photochromic inhibitors, solid solvents, surfactants, antistatic agents, and the like may be added to the medium of the present invention, if necessary.

The preferred blending ratio of the above components in the medium of the present invention is as follows.

The amount of the polymerization initiator is preferably 0.1 to 30 parts by weight, more preferably 0.1 to 30 parts by weight, per 100 parts by weight of the polymerization composition.
5 parts by weight to 20 parts by weight are used. Further, the content of the thermally diffusive substance is preferably 2.5 parts by weight to 50 parts by weight, more preferably 5 parts by weight, based on 100 parts by weight of the polymerizable compound, polymerization initiator, and optionally contained bangu. Parts to 20 parts by weight are used.

Note that the shape of the image forming medium of the present invention when molded into a desired shape is not particularly limited, such as a flat plate, a cylindrical shape, a roll shape, and the like. The thickness of each layer is preferably 0.1 part m to 2 mm, preferably 1 μm to 0.1 m.
It is said to be about m. Note that the number of layers that the image forming medium has is not limited to two layers, and may have a multilayer structure of more than two layers.

[Example] Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 (Liquid A) 3.3'-carbonylbis(7-medoxycoumarin) 016 parts Ethyl p-dimethylaminobenzoate 0.04 parts Pentaerythritol tetraacrylate ], ]O parts Acrylic-styrene copolymer 1 .0 parts Methyl ethyl ketone 10 parts (Liquid B) Diffusible dye MS Macenta vp (manufactured by Mitsui Toatsu) 0.3 parts Acrylic-styrene copolymer 1.0 parts Methyl ethyl ketone 10 parts Prepare liquids A and B having the above compositions. I got it. Using an applicator, apply the B solution onto a heat-resistant polyethylene terephthalate (PET) film with a thickness of 6 JIm to a dry film thickness of 3 μm.
A coloring material layer was formed by applying the coloring material so as to form a coloring material layer. Next, liquid A was applied onto this coloring material layer so that the dry film thickness was 3 μm to form a polymerized layer. Then, on top of this polymerized layer, 3 μm
An image forming medium was obtained by providing a polyvinyl alcohol (PVA) film.

The PVA film of the medium was exposed together with the negative image to form a latent image. In addition, the exposure at that time is 3 as a light source.
A fluorescent lamp with a 50 nm fluorescence peak was used for 20 seconds with the light source 3 cm away from the imaging medium.

In addition, when we took out the completely polymerized part and the completely unpolymerized part of this latent image and measured the Tg of each part using the viscoelasticity measurement method, the T g 2 of the polymerized part was 120°C, and the T g of the unpolymerized part was measured. + was 50°C. That is, Tg2 T
g+=70°C.

The PVA membrane was then removed by washing the medium with water. Next, water was sufficiently removed, and then synthetic paper with an image-receiving layer formed of polyester resin was used as an image-receiving body, and the polymerized layer and image-receiving layer were stacked face-to-face at 100°C for 10 seconds from the PET film side. By heating, the dye in the color material layer was diffused and transferred to the image-receiving layer through the polymerization layer, and a clear red dye-side image was obtained on the image-receiving paper.

In the above transfer, the dye in the area corresponding to the unpolymerized area is transferred well to the image-receiving layer, and the optical density of the transferred image area is 1≧
It was 0 or more” 2. On the other hand, almost no dye was transferred at the portion corresponding to the polymerized portion, and the optical density on the image-receiving layer corresponding to the polymerized portion, that is, the “fog density” was about 0.03.

In addition, when images were formed at various temperatures within the temperature range of 50°C (Tg+) to less than 120°C (Tg2),
In both cases, the Kafuri concentration is 0. At a temperature (90° C. or higher) at which the dye was sufficiently sublimated, the optical density of the transferred image area was 2.0 or higher.

Comparative Example 1 An image was formed in the same manner as in Example 1 except that the transfer temperature was 130° C. or higher, but the fog density was as high as about 0.3.

Comparative Example 2 An image was formed in the same manner as in Example 1 except that the transfer temperature was lower than 50° C. (Tg+), but no image was transferred at all.

Example 2 (Liquid A) Acrylic-styrene copolymer 10 parts Kayar
ad D P HA (manufactured by Nippon Kayaku@→) 10 parts benzoyl peroxide O,] parts methyl ethyl ketone 80 parts (liquid B) Butyral 7 parts Diffusible dye MS cyan vp (manufactured by Mitsui Toatsu Chemical Im) 3 parts xylene/ Butanol (1:1) 90 parts Solutions A and B having the above composition were prepared. This B solution was applied onto a heat-resistant PET film (x) having a thickness of 6 μm using a wire bar so as to have a dry film thickness of 3 μm to form a coloring material layer. Next, on this coloring material layer, liquid A was applied using a wire bar so that the dry film thickness was 3JIm to form a polymerized layer. This polymerized layer is then coated with 4.5 μm PE.
An image forming medium was obtained by laminating the T film (y).

A thermal head was applied to the PET film (X) of this medium, and a heating element generated heat in accordance with an image signal to form a latent image.

In addition, when the polymerized and unpolymerized parts of this latent image were taken out and the Tg of each part was measured using a viscoelasticity measurement method, the Tg 2 of the polymerized part was 150°C, and the Tg of the unpolymerized part was measured.
+ was 60°C. That is, Tg2-Tgl =
The temperature was 90°C.

Next, the laminate layer of the medium was peeled off. Thereafter, synthetic paper with an image-receiving layer formed of polyester resin was used as an image-receiving body, and the polymerized layer and image-receiving layer were stacked so as to face each other at 100°C.
Heating from the PET film (x) side for 10 seconds,
The dye in the coloring material layer was diffusely transferred to the image receiving layer through the polymerization layer to obtain a clear blue dye image on the image receiving paper.

In the above transfer, the dye in the area corresponding to the unpolymerized area was transferred well to the image receiving layer, and the optical density of the transferred image area was 17.
That was it. On the other hand, almost no dye was transferred in the region corresponding to the polymerized region, and the fog density was about 0.0 part.

In addition, 60°C (Tgl) or higher and 150°C (T g 2 )
When images were formed at various temperatures within a temperature range of The concentration was 1.5 or higher.

Comparative Example 3 When an image was formed in the same manner as in Example 1 except that the transfer temperature was 160° C., the fog density was approximately 0 parts.

Comparative Example 4 An image was formed in the same manner as in Example 1 except that the transfer temperature was 40° C., and the optical density of the transferred portion was O.

Example 3 (Liquid A) Acrylic-styrene copolymer 1 part Kayar
ad D P HA (manufactured by Nippon Kajimi Co., Ltd.) 10 parts Benzoyl peroxide 0.1 part Methyl ethyl ketone 80 parts (Liquid B) Methyl meccrylate-butyl methaxolate copolymer 17 parts Diffusible dye: Niayarad Red B ( (manufactured by Nippon Kakami Co., Ltd.) 3 parts Methyl ethyl ketone 90 parts After preparing Solutions A and B having the above compositions, image formation was performed in the same manner as in Example 1. At this time, as a negative film, G
As a result of exposure using Ray 5cale (manufactured by Odak (TL→)), a clear red dye image was obtained on the receiving image, and at the same time, a good gradation image corresponding to Gray 5cale was obtained.

Example 4 (Liquid A) Acrylic-styrene copolymer 3 parts saturated boron ester resin 1 part chlorinated polyethylene resin 6 parts Aronix M-40010
Part 2.4-diethyldioxanthone 1 part Dimethylamine ethyl benzoate 1 part Methyl ethyl ketone 78 parts (B liquid) Polyvinyl butyral 10 parts MS Magenta VP 2 parts Toluene/ethanol (]:I vol ratio) 88 parts Composition A solution A and a solution B were prepared.

The B liquid was applied onto a heat-resistant treated PET film having a thickness of 6JJI11 using an applicator so that the dry film thickness was 3 μm to form a coloring material layer. Next, add liquid A,
A polymerized layer was formed by coating on this coloring material layer so that the dry film thickness was 3 μm. Then, on top of this polymer layer, six PE
A T film (transfer target) was laminated to obtain an image forming medium.

A latent image was formed on this image forming medium in the same manner as in Example 1 except that the wavelength of the fluorescent lamp was changed to 380 nm, and then the PET film (transferred material) was peeled off, and the unpolymerized portion was peeled off. As a result, some polymerized portions remained on the image forming medium side. The same image receptor as in Example 1 was pasted onto the remaining polymerized area and 10
It was heated at 0° C. for 10 seconds to diffusely transfer the dye in the color material layer to the image-receiving layer, thereby obtaining a clear red image on the image-receiving layer.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to obtain a good image with high contrast and no fog. Further, a high gradation image can be formed with easy control and easy operation. Furthermore, even if the color tone of the dye in the color material layer is changed, a color image can be quickly formed using a polymer layer having the same structure.

[Brief explanation of drawings]

FIGS. 1 to 3 are schematic diagrams sequentially showing one aspect of each step in the method of the present invention, FIGS. 4 and 5 are diagrams illustrating the relationship between heating temperature and optical density of the diffusion transfer portion, and FIGS. 6 and 7 are schematic diagrams sequentially showing one embodiment of the latent image peeling and transfer step in the method of the present invention. ] ... Polymerization layer 3 ... Support 2 ... Photosensitive layer 4 ... Negative mask 5 ... Substrate 7 ... Transferred object 6 ... Image-receiving layer

Claims (1)

[Scope of Claims] 1) Site-selectively polymerizing the polymer layer of an image forming medium having a coloring material layer containing at least a heat-diffusible substance and a polymer layer containing at least a polymerizable compound and a polymerization initiator. A process of forming a latent image consisting of the polymerized portion and the unpolymerized portion, and superimposing the image forming medium on which the latent image is formed on an image receptor and heating it so as to satisfy the following formula (A), Tg_1≦T_t_r_a_n_s≦Tg_2...(
A) (In the formula, T_t_r_a_n_s represents the temperature of the image forming medium, Tg_1 represents the glass transition temperature of the unpolymerized portion, and Tg_2 represents the glass transition temperature of the polymerized portion.) Heat contained in the coloring material layer An image forming method comprising transferring a diffusible substance site-selectively to an image receptor through the polymer layer to form an image made of the heat-diffusible substance on the image receptor. 2) By site-selectively polymerizing the polymer layer of an image forming medium having a coloring material layer containing at least a heat-diffusible substance and a polymer layer containing at least a polymerizable compound and a polymerization initiator, and heating the image forming medium on which the latent image is formed so as to satisfy the following formula (A), Tg_1≦T_t_r_a_n_s≦Tg_2...(
A) (In the formula, T_t_r_a_n_s represents the temperature of the image forming medium, Tg_1 represents the glass transition temperature of the unpolymerized portion, and Tg_2 represents the glass transition temperature of the polymerized portion.) Heat contained in the coloring material layer An image forming method comprising selectively diffusing and removing a diffusible substance through the polymeric layer to form an image on the image forming medium made of the remaining thermally diffusive substance. 3) An image forming medium having at least a coloring material layer containing a heat diffusible substance and a polymer layer containing at least a polymerizable compound and a polymerization initiator, the polymer layer of the image forming medium being site-selectively polymerized. An image forming medium characterized in that it is possible to form a latent image consisting of a polymerized portion and an unpolymerized portion satisfying the following formula (B). Tg_2-Tg_1≧30°C...(B) (In the formula, Tg_1 represents the glass transition temperature of the unpolymerized part, and Tg_2 represents the glass transition temperature of the polymerized part.) 4) At least a thermally diffusive substance A latent image consisting of the polymerized portion and the unpolymerized portion is formed by site-selectively polymerizing the polymerized layer of the image forming medium, which has a coloring material layer and a polymerized layer containing at least a polymerizable compound and a polymerization initiator. The process of forming a latent image and transferring the polymerized portion or unpolymerized portion to a transfer object depending on the difference in tackiness of the latent image, and heating the transferred image forming medium by overlapping it with the image receptor to transfer the color. An image forming method comprising the steps of selectively transferring a thermally diffusible substance contained in a material layer onto an image receptor, and forming an image made of the thermally diffusive substance on the image receptor.