JPH0210341A - Transfer recording medium - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a transfer recording medium that can be used in recording devices such as printers, copying machines, and facsimile machines.

[Conventional technology and issues]

In recent years, with the rapid development of the information processing industry, various image recording methods have been developed. The thermal transfer recording method, which is one of such recording methods, has excellent operability, is compact, and has little noise, and the transfer recording medium used in the thermal transfer recording method has excellent storage stability. However, in order to obtain a multicolor image using a thermal transfer method, it is necessary to repeat the transfer multiple times to overlap the colors, making it difficult to obtain an image without color shift.

On the other hand, a method of forming a multicolor visible image using a color former and a color developer is known. For example, U.S. Patent 4,399,
The specification of No. 209 uses a recording medium in which microcapsules containing a photosensitive composition and a coloring agent are arranged on a base material, and the photosensitive composition in the microcapsules is exposed mainly to ultraviolet light converted according to a recorded image. harden the object to form a transferred image,
Furthermore, a transfer system is disclosed in which the transferred image is superimposed on a recording medium having a color developer layer and passed through a nip between a pair of pressure rollers to destroy the microcapsules and also serve as an image. In this image forming method, a color former is imagewise transferred to an image forming sheet, and the color former reacts with a color developer to form an image, thereby obtaining a multicolor image.

Further, US Pat. No. 4,416,966 discloses a self-contained color developer in which the color developer is present on the same support surface as the photosensitive microcapsules.
An image forming system is disclosed. In this system,
After being exposed by mainly ultraviolet light converted according to the recorded image, when the imaging sheet is passed through a pressure roll,
The microcapsules rupture, releasing the internal phase image-wise.

The color former is then transferred to a layer containing the color developer, usually provided in a separate layer 18, where the color former reacts with the developer and forms a color image.

However, in this method, if the microcapsules containing the color former are not completely cured, slight color development will occur even due to the image-forming release of a small amount of the internal phase, resulting in poor color tone such as decreased saturation. In addition, in order to prevent this, it is necessary to irradiate multiple liters of light to completely cure the microcapsules, resulting in problems such as the inability to obtain recorded images at high speed.

All of the recording methods such as L2 method contain a photopolymerization initiator in a microcapsule, and the photopolymerization initiator is made to have different photosensitive wavelength ranges, and the main photopolymerization initiator is converted to correspond to each photosensitive wavelength range. The self-soluble material inside the microcapsules is cured using ultraviolet light. However, a common problem with these methods is that the means used for image formation mainly irradiates only ultraviolet light, that is, optical energy, onto a substrate on which microcapsules are arranged, thereby forming a transferred image on a recording medium. Therefore, in order to obtain clear recorded images at high speed, it was necessary to use a photosensitive material with high sensitivity to light or to irradiate it with high energy light.

However, high-sensitivity recording media that utilize only photoreactions have fatal drawbacks such as high reactivity when irradiated with light and poor storage stability near room temperature. Furthermore, in order to obtain high-energy light, the apparatus becomes large, and in order to obtain multicolor recording, the apparatus becomes large and the apparatus cost becomes large, which is not desirable in practice. In addition, since the above method forms an image using only light energy, it can be used when outputting an image in response to an external signal, such as in a printer, or when reading an image from a color original, as in a color copying machine. It is not suitable for applying image information to a recording medium after converting it into a digital signal using a color image scanner. That is, when irradiating high-energy light, it is necessary to use short wavelength light, mainly ultraviolet light, and a digitally controllable light source for ultraviolet light is currently not available. For example, as a method to obtain a digital light source, the application of optical heads such as liquid crystal shutter arrays and LED arrays is being considered, but although these are suitable for miniaturization, the deterioration of liquid crystal molecules at wavelengths in the ultraviolet region is considered. UV light cannot be extracted.

Furthermore, in order to facilitate development by applying pressure after exposure, the contents of the microcapsules must be a photosensitive composition that has a liquid phase at room temperature, resulting in poor storage stability and poor image quality. Due to the destruction of unreacted substances, there is a lingering odor, which is a characteristic that is undesirable for practical purposes.

The present invention provides an image forming method that solves the above conventional problems,
In other words, high-quality transfer images can be formed, high-speed recording is possible,
It is capable of half-tone recording and can be effectively applied to an image forming method that can obtain a clear multicolor image without color shift without making complicated movements of the transfer medium even when obtaining a multicolor transfer image. The main purpose is to provide recording media.

A further object of the present invention is to provide a recording medium that does not require a special color developing layer and can form a clear transferred image on commonly used plain paper with low surface smoothness.

A further object of the present invention is to provide a highly sensitive recording medium that can record digital images with low power without requiring a special digital light source with high optical energy.

A further object of the present invention is to provide a recording medium with high storage stability and high sensitivity.

A further object of the present invention is to provide a recording medium that can produce clear, high-gradation, multicolor recorded images with a small, inexpensive device.

A further object of the present invention is to provide a recording medium that can be used in an image forming method that has extremely little environmental dependence during transfer image formation.

[Means for solving problems]

The present invention provides microcapsules that contain a dye precursor and have an internal phase whose physical properties governing transfer characteristics change upon application of light and thermal energy, and a color developer that develops color from the dye precursor in the same support. The transfer recording medium is characterized in that the color developer for the dye precursor is present on the support in a non-contact state with the dye precursor.

The applicant previously filed an application for a transfer recording medium having microcapsules containing a photothermally sensitive substance and a colorant as an internal phase that are solid at room temperature, and an image forming method using the transfer recording medium. (Patent application 1986-150597, etc.).

The transfer recording media filed earlier had a colorant, and did not have a color former and a color developer on the same support.

In the transfer recording medium of the present invention, the color developer contained on the same support is a color developer that comes into contact with the dye precursor contained in the internal phase of the microcapsules when the internal phase of the microcapsules is transferred to the transfer target. It refers to a color developer located on a support such that it can develop color. Specifically, the arrangement of the color developer in such a state is such that, for example, the wall material of the microcapsule itself, which has an internal phase containing a dye precursor, is made of a material that exhibits color developing properties for the dye precursor. Containing or supporting a color developer in the wall material of the microcapsules; Containing it in a binder that binds the microcapsules and the support; An internal phase of the microcapsules separate from the microcapsules; Alternatively, it can be obtained by a method such as incorporating it into a wall material.

As mentioned above, in the transfer recording medium of the present invention, since the dye precursor and the color developer in the internal phase of the microcapsules are present on the same support as the microcapsules, special There is no need to use a standard recording medium, and recording can be easily performed on commonly used plain paper.

Furthermore, since the transfer recording medium according to the present invention contains an essentially colorless dye precursor that develops color by reacting with a color developer in the internal phase of the microcapsules, a) microcapsules that have hardened and lost their transferability; For example, even if the capsules are transferred to an object due to the adhesiveness of microcapsules that are not hardened and have transferability, they will not react with the color developer and develop color due to hardening, so they will not become noise components. The color saturation is improved.

b) In principle, the thermal transfer method can take only two values: transfer and non-transfer, and gradation control is area gradation and dither, but in the present invention, the color density of the dye precursor can be adjusted depending on the degree of curing. Since the density changes, a density gradation method can be adopted.

It has the following advantages.

As the color developer that can be used in the present invention, color developers that are commonly used in carbonless paper can be used. Such color developers include, for example, acid clay, activated clay,
Tannic acid, erosion acid, benzoic acid, or their aluminum salts, magnesium salts, etc., or acid polymers such as bisphenol A, phenol formaldehyde resin, maleic acid-rosin acid, copolymerization of maleic anhydride with styrene, ethylene, etc. There is such a thing as merging. As described above, such a color developer may be contained or supported in, for example, a binder, a wall material of a microcapsule, an internal phase or a wall material of a separate microcapsule, or the like.

Furthermore, as the wall material of the microcapsules having color developing properties, phenol resin, hydroxystyrene resin, polyacrylic acid, polymethacrylic acid, etc. are used.

Examples of the dye precursor that can be used in the present invention include essentially colorless electron-donating compounds that develop color upon reaction with a color developer. Such dye precursors include those having, for example, a lactone, lactam, sultone, spiropyran, ester or amide structure in the skeleton, such as triarylmethane compounds, bisphenolmethane compounds, xanthine compounds, fluoranes, triazine compounds, spiropyran compounds, etc. Specific examples include crystal violet lactone, malachite green lactone, benzoylleucomethylene blue, 3-diamino-7-methylaminofluoran, 3-dimethylamino-6-medoxyfluoran, etc. .

On the other hand, when the internal phase of the microcapsules in the transfer recording medium of the present invention is simultaneously applied with sales floor and thermal energy, the physical properties governing its transfer characteristics change. Therefore, as mentioned above, U.S. Patent 4. : Problems with recording media described in Specifications No. 199,209, Specifications 4,416,966, etc. (images are not clear, storage stability is poor, equipment costs are high, digital control is not possible, monomers present) (strong smell, etc.) can be solved.

For example, when focusing on image clarity and high sensitivity, the transfer recording medium of the present invention can provide effects as detailed below.

FIG. 1 is a diagram showing the principle of obtaining clear images with high sensitivity according to the present invention, and shows the relationship between the light irradiation time and the optical density of the obtained image.

(a) shows the light irradiation time and the optical (b) shows the relationship between the concentration and the light irradiation time in a transfer recording medium in which microcapsules whose internal phase is a photothermally sensitive component whose transfer characteristics change and a pigment as a coloring agent are supported on a support. and the optical density of the transferred image, and (c) shows the relationship between microcapsules whose internal phase is a photothermally sensitive component whose transfer characteristics change and a dye precursor and a color developer are supported on the same support -F. The relationship between the light irradiation time and the optical density of a transferred image in a transfer recording medium made of

As is clear from FIG. 1(a), in a recording medium composed of a dye precursor and a color developer, the amount of change in optical density is large within a short range of light irradiation time; In the long range of , the optical density tends to be saturated. Therefore, a large amount of light irradiation time is required to reduce the color development due to the reaction between the dye precursor and the color developer to an unrecognizable level.

Furthermore, as is clear from Fig. 2(b), in transfer recording media that use coloring materials such as pigments, the change in optical density is extremely steep because the transfer and non-transfer processes are, in principle, binarized. Therefore, it is difficult to perform density gradation.

On the other hand, in the recording medium (C) of the present invention, since the optical density of the transferred component can be controlled by the amount of light irradiation, good density gradation can be achieved. Furthermore, since the microcapsules are no longer transferred when the amount of light irradiation exceeds a certain range, even if the element body develops a small amount of color, it is not transferred to the transfer target, making it possible to easily perform highly sensitive transfer recording.

Next, specific examples of components other than the above-mentioned color developer and dye precursor among the constituent components of the transfer recording medium of the present invention will be described in detail.

The internal phase of the microcapsules of the transfer recording medium of the present invention is:
In addition to the dye precursor described above, it contains a polymerization component, a photopolymerization initiator, and the like.

As the polymerization component for forming the internal phase of the microcapsules, monomers or oligomers having unsaturated double bonds are preferably used. Specific examples include rubbers such as epoxy acrylate, urene acrylate, oligoester acrylate, diaryl phthalate resin, butadiene or isoprene oligomer, and the like. More specifically, ethylene glycol diacrylate,
Ethylene glycol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate,
Epoxy acrylates, toluene diisocyanate, hexamethylene diisocyanate, and cyclohexyl acrylates synthesized by the reaction of acrylic acid or methacrylic acid with epoxy compounds made from the reaction products of polyhydric alcohols such as bisphenol A, hexanediol, and Talezol novolac resins with epichlorohydrin. silane diisocyanate, 4,4゛-diphenylmethane diisocyanate, 4
, 4'-dicyclohexylmethane diisocyanate and other urethane acrylates, poly(0- diaryl phthalate), poly(isodiaryl phthalate), butadiene rubber, isoprene rubber, cyclized isoprene rubber, or polymer compounds containing acrylic acid and methacrylic acid, and glycidyl methacrylate, glycidyl acrylate, acrylic acid chloride,
Examples include prepolymers made of reaction products with methacrylic acid chloride.

Examples of the photopolymerization initiator used in the present invention include radical initiators such as azo compounds, organic sulfur compounds, carbonyl compounds, and halogen compounds. Also,
Photosensitive dyes can also be used in concentrations and amounts that are negligible for the image. For example, benzophenone, benzyl,
Carbonyl compounds such as benzoin, ethyl ether, 4-N,N-dimethylamino-4'-methoxy-benzophenone, dibutyl sulfide, benzyl disulfide,
Organic sulfur compounds such as decylphenyl sulfide;
Carbon peroxide tetrachloride such as ert-butyl peroxide and benzoyl peroxide; halogen compounds such as silver bromide and 2-naphthalenesulfonyl chloride; and nitrogen compounds such as azobisisobutyronitrile and benzenediazonium chloride.

In addition to these components, the transfer recording layer may contain stabilizers such as hydroquinone, p-methoxyphenol, p-tert-butylcatechol, 2,2'-methylene-bis(4-ethyl-6-tert-butylphenol), etc. It may contain a curing agent.

Furthermore, in order to improve the dispersibility of each component such as the photopolymerization initiator, acrylic resin, styrene resin,
A polymer compound such as a vinyl chloride resin, a chlorinated olefin resin, a polyester resin, or an amide resin may be included.

Materials used for the wall material of microcapsules include materials other than those shown above that exhibit color developing properties, such as gelatin, gelatin-gum arabic, ethyl cellulose, cellulose-based urea-formalin such as nitrocellulose, nylon, and tetron. , polyurethane, and polycarbonate are used.

Any conventionally known method can be applied to form the microcapsules consisting of the internal phase and wall material described above, such as simple coacervation method, complex coacervation method, interfacial polymerization method, 1n-sit method, etc.
U-polymerization method, interfacial precipitation method, phase separation method, spray drying method, air suspension method, mechanochemical method, etc. are used.

Next, the microcapsules thus obtained are bound onto a support using a binder. As the support, for example, PET film, polyamide film, polyimide film, capacitor paper, PPS film, etc. may be used. Moreover, various adhesives such as epoxy adhesive, urethane adhesive, acrylic adhesive, polyester adhesive, etc. can be used as the binder.

If the transfer recording medium of the present invention obtained as described above is used in the image forming method described in Japanese Patent Application No. 60-150597, etc., a good transfer image can be obtained.

〔Example〕

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

Example! 10 parts by weight of the components shown in Table 1 are mixed with 20 parts by weight of methylene chloride, mixed with 200 ml of water in which 1 g of gelatin and a surfactant such as a cation or nonion having an HLB value of at least 10 times are dissolved, and heated at 60°C. The mixture was emulsified by stirring at 8,000 N and 10,000 rpm using a lower homomixer to obtain oil droplets with an average particle size of 5 μm.

Stirring was further continued at 60° C. for 30 minutes, and methylene chloride was distilled off to reduce the average particle size to 3. To this, add 20 ml of water in which 1 g of gum arabic was dissolved, cool slowly, then add NH4 leaves (ammonia) water to make the pH 11 or higher to obtain a microcapsule slurry, and slowly add 10 mA of a 20% glutaraldehyde aqueous solution. The capsule wall was hardened.

After that, solid-liquid separation was carried out using a Nutsche filter, and 35
C. for 10 hours to obtain a microcapsule-shaped image forming element.

Saturated polyester resin with 25 wt% bisphenol A added (Gohsenol 022, manufactured by Nippon Gosei Kagaku Kogyo Co., Ltd.)
was diluted 10 times with toluene and applied to a 6 μm thick PET film with an applicator to a thickness of 1 scale to form a binding layer. The above-mentioned microcapsules were evenly sprinkled on the main binding layer, and heated with a 100°C heat roll at a pressure of 2.
~3 g/crn' was given and bound.

Using the transfer recording medium obtained by the above method, an image forming experiment described below was conducted.

The PET side of the transfer recording medium was placed in close contact with a hot plate heated to 120°C, and from the side facing the transfer recording layer surface, the spectral characteristics shown as A in Figure 2 were obtained. Fluorescent lamp Fl, 205E II)~5
Each desired position was irradiated over a period of 0 m5 cc. Note that C in FIG. 3 shows the absorption spectrum of the photoinitiator contained in the microcapsules. The transfer recording medium after heat irradiation was passed between two rollers that were pressed against each other and overlapped with the recording paper in a river where the transfer recording layer of the transfer recording medium was in contact with the recording paper whose surface smoothness was about 10 to 20 seconds. .

The pressure between the rollers was set to about 258 g/crn'',
In addition, the surface temperature of the roller in contact with the transfer recording medium is set to 1 in advance.
It was heated to 30°C. When the transfer recording medium and the recording paper were separated after being passed between rollers, a high-quality purple image was obtained on the recording paper. When the density of this image was measured using a Macbeth optical densitometer, the relationship between the light irradiation time and the density was as shown in Figure 4, as shown in the principle diagram, and a high sensitivity with good gradation was obtained. It was done.

Example 2 2 g of microcapsules prepared in Example 1 and 0 activated clay
．． 5 g of the microcapsules were put into a coffee mill and stirred for about 2 minutes to make the outer walls of the microcapsules support activated clay.

Next, a binding layer was applied on the PET film in the same manner as in Example 1 except that bisphenol A was not added and the lid was removed, and the microcapsules were bound in the same manner as in Example 1. Next, an image forming experiment was conducted in the same manner as in Example 1, and an image with good gradation could be formed.

Example 3 20 wt% of the ingredients shown in Table 1 was prepared by the method shown below.
The chloroform solution and locresol were each microencapsulated.

That is, 26 g of isobutylene maleic anhydride copolymer was dissolved in 100 g of water, and after stirring for 10 minutes, 3
．． 1 g of pectin was added and stirred for 20 minutes. This liquid was adjusted to pl+=4.0 with a 20wt% sulfuric acid solution and 0.2
g of Quadrol (IIASF) was added. While this liquid was maintained at 60° C. and stirred at 6000 rpm with a homomixer, a chloroform solution of the components shown in Table 1 was added, and stirring was continued for 5 minutes. Next, stirring was continued at 200°C for 6 hours, and after distilling off the chloroform, 16.6
g of 50 wt% urea solution, 0.8 g of resorcinol dissolved in log of water, 21.4 g of formalin (37 wt%)
, and 0.6 g of ammonium sulfate dissolved in 10 ffil of water were added and stirred at 60° C. for 2 hours. After the film was cured, the pH was adjusted to 9.0 with a 20 wL% sodium hydroxide solution while lowering the temperature to room temperature, and the film was filtered and dried in the same manner as in Example 1. Furthermore, by the above method,
Microcapsules having O-cresol as the internal phase were prepared in the same manner as above except that ro-cresol was used instead of the chloroform solution containing the components shown in Table 1.

2 g of microcapsules containing the ingredients shown in Table 1 obtained in this way and 0.5 g of microcapsules containing ro-cresol were mixed, and P.
It was supported on an ET film, and an image was formed in the same manner as in Example 1. As a result of the above experiments, high quality images with good gradation were formed.

Example 4 20 g of methyl methacrylate and 20 g of methacrylic acid
It was dissolved in 0 cc of toluene and polymerized at 60°C for 2 hours using 0.5 g of N,N'-azoisobutyronitrile as an initiator. Then, the resin was poured into 500 d of cyclohexane, recovered, and dried.

2 g of the above resin was dissolved in an aqueous sodium hydroxide solution with a pH of 2.5, and then a surfactant such as a cationic or nonionic surfactant with an HLB value of at least 10 times or more was added. A solution obtained by dissolving 10 g of the indicated components in 30 g of chloroform was added. After stirring for 5 minutes to emulsify the cotton, 40℃, 500rpr
The mixture was stirred for 12 hours at a high temperature, and the chloroform was distilled off. Next, hydrochloric acid 50]1 diluted 10 times the volume was added dropwise over a period of 2 hours to effect encapsulation, followed by filtration and drying in the same manner as in Example 1.

A transfer recording medium was prepared in the same manner as in Example 1, and when an image was formed, a good image was obtained.

Example 5 The components shown in Tables 1 and 2 were each mascrocapsulated in the same manner as in Example 3, and 2 g of each and 1 g of the phenol-containing microcapsules prepared in Example 3 were mixed. It was supported on PET in the same manner as in 3.

Next, 20W fluorescent lamps FL20SE and FLIOA70E manufactured by Toshiba ■, which have the spectral characteristics shown in FIGS. 2A and 2B, were irradiated onto the desired positions for a period of 10 to 50 mS, respectively. Note that FIGS. 3C and 3D do not show the absorption spectra of the photoinitiators contained in the respective microcapsules. When the image was transferred to recording paper in the same manner as in Example 2, a high-quality image with good gradation was formed.

Table 1 Table 2 (Effects of the Invention) As explained above, the transfer recording medium of the present invention has a dye precursor and a color developer on the same support. There is no need to use a special recording medium, and a transferred image can be easily formed on commonly used plain paper.

Furthermore, when the microcapsules included in the transfer recording medium of the present invention are exposed to light and thermal energy, the physical properties that govern their transfer characteristics change. Its characteristics include clear images, good storage stability, low equipment costs, digital control, low odor of residual smudges, and easy multicolor printing.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the relationship between light irradiation on the transfer recording medium and optical density of the formed image, Fig. 2 is a diagram showing the spectral characteristics of the fluorescent lamp used in the example, and Fig. 3 is the example FIG. 4 is a diagram showing the relationship between the light irradiation time of the transfer recording medium of the present invention obtained in Example 1 and the optical density of the formed image.

Claims (4)

[Claims] (1) Microcapsules containing a dye precursor and having an internal phase whose physical properties governing the transfer characteristics change upon application of light and thermal energy, and a color developer that develops color from the dye precursor, on the same support. 1. A transfer recording medium characterized in that a color developer for the dye precursor is present on the support in a non-contact state with the dye precursor. (2) The transfer record according to claim 1, comprising two or more types of microcapsules in which the dye precursors contained in the internal phase develop different colors, and the wavelength range or intensity of the light differs depending on the different hues. Medium. (3) The transfer recording medium according to claim 1 or 2, wherein the color developer is contained or supported on the wall material of the microcapsules. (4) The transfer recording medium according to claim 1 or 2, wherein the color developer is contained in a binder that binds the microcapsules and the support.