JPH11157207A - Recording medium, method for forming image using recording medium, and manufacture of recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording medium which is highly water-resistant and is also of a high mechanical strength as well as an image forming method. SOLUTION: In the recording medium having an ink receiving layer 2 formed at least, on one of the faces of a base material 1, the ink receiving layer 2 is a porous layer containing pigment particles and mutually welded thermoplastic resin particles. The image forming method using the recording medium is to form an image by splashing ink using a jet recording process to the recording medium. The recording medium manufacturing method includes a step to apply a coating liquid containing pigment particles and thermoplastic resin particles and a step to weld the thermoplastic resin particles by heat under pressure to form the ink receiving layer 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a recording medium on which an image is formed by ink jet recording.

[0002] In particular, the present invention relates to a recording medium suitably used for a credit card, a bank card, a prepaid card, a clinic card, a member's card, and the like, an image forming method using the recording medium, and a method for manufacturing the recording medium.

[0003]

2. Description of the Related Art Conventionally, various kinds of information are embedded in cards such as credit cards, bank cards, prepaid cards, clinic cards, and members' cards. The method of recording information is to digitize the information and volatilize a part of the optical recording layer on the information recording carrier using magnetism, barcode, or laser light, change the reflectivity, or deform. A so-called optical card or the like is used in which information is recorded and reproduced based on a difference between an optical reflectance and a transmittance. In addition, general printing such as embossing in which characters and numbers are represented by convex portions obtained by deforming a card into irregularities, and screen printing and offset printing are also used.

However, data cannot be directly seen with magnetic recording, a bar code, or an optical card performed by digitizing information. Therefore, it is not easy to confirm whether the information recorded on the card is really the one of the card owner.

[0005] In addition, precautions, rules, and the like in use are printed with character information, and logos, base patterns, pictures, and the like are printed in advance by general printing such as screen printing or offset printing. However, in such printing, it is necessary to prepare printing plates for the number of colors to be printed, and it is difficult to make printing plates in a short time. Such printing is limited to the case where uniform information is embedded, and at the present time, individual information is separately recorded with the above-described digital data.

[0006] Embossing, which represents letters and numbers with convex portions deformed into irregularities, can be directly confirmed by eyes.
There are problems such as a small amount of information and difficulty in colorization. In addition, there is a problem that a recording area for magnetic recording, optical recording, or the like cannot be provided in an area where an emboss is provided because the card is deformed.

[0007] Recording of individual information, for example, a photograph of the face of the card owner on the card has been partially performed.

However, for example, it is difficult to create a photograph in a short time by a method of attaching a photograph itself to a card. Further, in the method of printing a photograph directly on a card, a problem such as an influence of a surface treatment or printing on an information recording medium occurs. Further, the method using the sublimation heat transfer type printing method has a disadvantage that the cost of the ink ribbon is high and the running cost is high. In addition, it is necessary to select a material having good printability as the material of the base.

As a method for solving these problems,
There is disclosed a card in which an ink receiving layer is laminated on a card base material and information is recorded by inkjet recording.

In Japanese Patent Application Laid-Open No. 57-784, an ink receiving layer is provided on a card medium, and an ink-permeable lubricating layer is further provided thereon.

However, since the coating solution is of a solvent type, there are safety and health problems and environmental problems. Further, when applied to a vinyl chloride base material usually used for a credit card, a bank card, and the like, the base material itself is violated by a solvent, causing warpage of a card and cracking of a coating film, which is difficult to apply.

Japanese Patent Application Laid-Open No. 64-43826 discloses a card in which an ink receiving layer is laminated on a card base material and information is recorded by ink jet recording. However, the water resistance of the receiving layer,
There seems to be a problem with durability.

Japanese Patent Publication No. 3-24906 discloses that the ink receiving layer contains a cationic hydrated aluminum oxide. JP-A-4-37577 discloses an ink receiving layer containing alumina hydrate.

Japanese Patent Publication No. 2-3673 discloses an ink jet recording medium in which an inorganic pigment layer having high ink absorbency is provided on a base material, and a thermoplastic organic polymer fine particle layer is sequentially laminated on the outermost layer. . JP-A-7-23734
No. 8 discloses an ink jet recording sheet in which a porous layer of alumina hydrate is provided on a base material, and a porous polymer layer is sequentially laminated on the outermost layer. Also, JP-A-8-
No. 2090 discloses a similar card type ink jet recording medium.

[0015] After performing ink jet recording,
This is to densify the outermost resin porous layer by heat treatment. The formation of an image, that is, the absorption and fixing of the ink, is mainly performed by an inorganic pigment layer such as a porous alumina hydrate, and the water-resistant durability is provided by a densified resin porous layer.

[0016]

However, the inorganic pigment layer such as porous alumina hydrate has poor flexibility, and when applied to the above-mentioned base material such as vinyl chloride, the ink receiving layer is deformed by embossing. The problem of peeling occurs. Further, when recording is performed with an inkjet ink using a pigment ink as a coloring material, the pigment particles of the coloring material do not enter the ink receiving layer, and there is a problem in the scratch resistance of the image. In addition, since vinyl chloride has a low softening point of 50 to 60 ° C., the base material is deformed during heat treatment for producing a recording medium or heat treatment for densifying the resin porous layer as the outermost surface layer. No effective means is disclosed.

An object of the present invention is to provide an excellent recording medium without deformation.

It is another object of the present invention to provide an image forming method for easily forming an image on the recording medium.

Another object of the present invention is to provide a manufacturing method for manufacturing a recording medium without deformation.

[0020]

According to the present invention, there is provided a recording medium comprising a base material having an ink receiving layer on at least one surface of a base material, wherein the ink receiving layer contains pigment particles and thermoplastic resin particles welded to each other. Characterized in that it is a layer.

In the image forming method of the present invention, an image is formed by flying ink on the recording medium by an ink jet recording method.

In the method for producing a recording medium according to the present invention, a step of applying a coating liquid containing pigment particles and thermoplastic resin particles to a base material, and applying heat under pressure to weld the thermoplastic resin particles. And a process.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to FIGS.

The substrate 1 used in the present invention is preferably a water-resistant one. This is because if the recording surface is not water-resistant, no matter how much water-resistant ink-receiving layer 2 is provided on the recording surface, if water enters from the substrate 1 side, a durable image recorded matter cannot be obtained. Suitable as the base material 1 are polyester resins such as polyethylene terephthalate and polybutylene terephthalate, terephthalic acid-ethylene glycol-cyclohexane dimethanol copolymer having the following structure, polyvinyl chloride resin, polyvinylidene chloride resin, epoxy resin, and polycarbonate. Resins, polyethylene resins, polypropylene resins, polystyrene resins, vinyl chloride, vinyl acetate copolymers, polycarbonates, resins such as acrylonitrile-butadiene / styrene copolymers, and polymers in which a copolymer of the following structural formula is mixed with polycarbonate Alloys and metals are also suitable for some applications. Considering the adhesiveness to the thermoplastic resin particles in the ink receiving layer, polyvinyl chloride resin, polyvinylidene chloride resin, polycarbonate resin, and polystyrene resin are preferable.

[0025]

[Outside 1]

On one or both sides of the substrate 1, a magnetic stripe, a magneto-optical recording layer, an IC or the like may be formed in advance for recording digital information, or a logo may be formed by screen printing or offset printing. And usage precautions,
Uniformly determined information such as rules may be printed in advance. That is, in the present invention, a portion on which various information is recorded may be formed in addition to the ink receiving layer 2. The thickness of the substrate 1 of the present invention is preferably from 0.2 to 1.0 mm, since deformation is unlikely to occur.

The ink receiving layer 2 may be provided on both sides of the substrate 1 and ink jet recording may be performed on both sides, or the ink receiving layer 2 may be provided on only one side. However, in the case of an optical card, an ink receiving layer is provided on the side opposite to the surface used for recording and reproducing optical recording.

The recording medium of the present invention has a side length or diameter of 30 to 1 due to the difficulty of deformation and the ease of handling.
A 30 mm rectangular or circular shape is preferred.

The size of the substrate 1 when the ink receiving layer 2 is applied may be a size previously formed into a final shape, or may be formed into a final shape after the ink receiving layer is provided. Is also good.

As the pigment particles in the ink receiving layer 2, silica gel, alumina hydrate, titanium oxide, calcium silicate, synthetic zeolite, zinc oxide, plastic pigment and the like can be used. The average particle size of the pigment particles is 0.0
1-5 μm is preferred.

As the thermoplastic resin particles in the ink receiving layer 2, particles of polyvinyl chloride, polyvinyl acetate, polyacrylate, polystyrene, polyethylene and the like can be used. Also, particles of a copolymer of a monomer corresponding to these can be used. The average particle size of the thermoplastic resin particles is preferably from 0.1 to 3 μm, more preferably from 0.2 to 2 μm. The ink receiving layer 2 contains thermoplastic resin particles welded to each other.

The purpose of using the thermoplastic resin particles is to solidify the pigment by welding and to obtain close contact with the substrate 1. Therefore, a material in which the thermoplastic resin particles are welded to the base material by heating is preferable. Further, when a pigment ink is used as the color material of the ink, there is no dropout of the color material due to rubbing, that is, the rubbing property is improved. Although the mechanism for improving the abrasion is not clear, it is considered that the thermoplastic resin particles are deformed by welding and leave a large gap, so that the pigment ink particles may easily enter. However, if the amount of the thermoplastic resin particles is excessively increased, the gap decreases,
The ink absorbency deteriorates, and a printing medium with good print quality cannot be obtained.

In order to achieve the above object, the ratio of the pigment particles to the thermoplastic resin particles in the receiving layer 2 is in the range of 1 to 40 parts by weight of the thermoplastic resin with respect to 100 parts by weight of the pigment, and 3 It is appropriate to select from -20 parts by weight.

If necessary, the ink receiving layer 2 may contain a water-soluble polymer as a binder resin.
For example, polyvinyl alcohol or a modified product thereof, starch or a modified product thereof, gelatin or a modified product thereof, casein or a modified product thereof, gum arabic, cellulose derivatives such as carboxymethylcellulose, hydroxyethylcellulose, and hydroxypropylmethylcellulose, and polyvinylpyrrolidone can be used. . The mixing ratio of the pigment particles to the binder is such that the binder is added to 100 parts by weight of the pigment.
It is preferably at most part by weight. More preferably, the amount is 15 parts by weight or less. If the amount of the binder is larger than the above range, the gap between the pigment particles will be closed, so that the ink absorbency will deteriorate.

If necessary, a pigment dispersant, a thickener, an antifoaming agent, a foam inhibitor, a fluorescent brightener, an ultraviolet absorber, an antioxidant, an anti-foaming agent, and the like can be appropriately blended.

When these materials are applied on a substrate, the polymer component is dispersed or dissolved using an appropriate solvent, and the pigment component is dispersed as finely as possible to form a coating solution. Alternatively, a method in which powders are mixed well and put into a mold together with a base material and then molded can be used.

The most preferable method is a mode in which these materials are used by dispersing them in a solvent mainly composed of water.

When the material is a dispersion, the method for applying the ink-receiving layer on the substrate may be a commonly used method such as screen printing, a blade coater, an air knife coater, a roll coater, a curtain coater, a bar coater, or a spray coater. A method is used.

The coating amount is from 3 to 80 as dry solids.
g / m ^2, preferably from 5 to 40 g / m ^2. 3 g / m ²
If the amount is less than the above range, the ink absorbency is not sufficient and a good image cannot be formed. For coating weights greater than 80 g / m ² ,
It is difficult to obtain this amount of coating in a single operation, and a large number of coating operations are required, which is disadvantageous in terms of cost.

Thereafter, drying is performed using, for example, a hot-air drying furnace or a hot drum. At this time, if the base material is a material having a low softening point, such as a vinyl chloride resin, the drying temperature may be 6
0 to 70 ° C. is the limit temperature at which the deformation of the substrate does not occur.

Finally, in the present invention, a heat treatment for welding the thermoplastic resin particles is performed. Since the heat treatment temperature varies depending on the types of the base material and the thermoplastic resin particles, it cannot be unconditionally determined, but is preferably in a range of approximately 70 to 180 ° C. This temperature is higher than the welding temperature of the thermoplastic resin particles used.
Here, the welding temperature corresponds to the film forming temperature in the case of an emulsion, and corresponds to the molding temperature in the case of a molding resin.
Here, as described above, when the base material is a material having a low softening point, such as a vinyl chloride resin, the base material is deformed when the welding temperature is 60 ° C. or higher. Therefore, the present invention is characterized in that when such a substrate is used, heat treatment is performed while restraining the substrate under pressure. When the pressure is applied, the surface shape of the object to be pressed is transferred to the base material or the ink receiving layer. Therefore, it is preferable to apply the pressure with a flat surface such as a ferroplate (chrome-plated iron plate). However, in particular, if it is desired to obtain a pear-skin pattern or a specific surface shape on the surface, it is sufficient to apply pressure with an object having a shape corresponding to that. As a material used for pressurization, plastic, ceramic, glass, or the like can be used in addition to metal such as a ferroplate. The applied pressure is determined by the material of the base material and the material of the ink receiving layer, but is 0.01 to 20 kg / cm.
² , further 0.01 to 15 kg / cm ² , especially 0.01 to 5 kg / cm ²
It is preferable to adopt in the range. If the pressure is too low, the adhesion to the substrate is not sufficient, and if the pressure is too high, the substrate is crushed or the gaps in the ink receiving layer are undesirably crushed. The heat treatment time is preferably from 5 minutes to 10 minutes. After heat treatment, cool to room temperature under pressure.

A more preferred embodiment of the recording medium of the present invention is
The outermost layer 3 composed of a porous layer containing thermoplastic resin particles is provided on the ink receiving layer 2.

The thermoplastic resin particles used for the outermost layer 3 include the above-mentioned polyvinyl chloride, polyvinyl acetate, and the like.
Particles of polyacrylate, polystyrene, polyethylene and the like can be used. Also, particles of a copolymer of a monomer corresponding to these can be used.

The average particle size of the thermoplastic resin particles used in the present invention is more preferably 0.1 to 3 μm, further preferably 0.2 to 2 μm, and most preferably 0.2 to 0.8 μm.
Range.

The average particle size of the thermoplastic resin particles is 0.1
If it is smaller than μm, the absolute pore volume of the outermost layer becomes small, and the ink absorbency and the image quality deteriorate. On the other hand, when the average particle diameter exceeds 5 μm, the surface becomes difficult to smoothen and the luminous intensity decreases when the non-porous treatment is performed after printing.

The porous layer containing the thermoplastic resin particles is formed by applying a coating liquid in which the solid content of the thermoplastic resin particles is adjusted to a range of 10 to 50% by weight on the ink receiving layer provided above. It is formed by coating as.

The coating amount of the thermoplastic resin particles is required to be such a thickness as to suppress the occurrence of interference light and to sufficiently function as a protective layer, and is usually applied to a dry thickness of 2 to 10 μm. Preferably.

As the ink used for ink jet recording on the above recording medium, known inks can be used without any problem. As the colorant, a direct dye, an acid dye, a basic dye, a reactive dye, a water-soluble dye represented by an edible dye, a disperse dye, and a pigment can be used, and there is no particular limitation. If importance is attached to the weather resistance of the coloring material, it is preferable to use a pigment dispersion. These coloring agents
It is generally used in a conventional ink at a ratio of 0.1 to 20% by weight, and this ratio may be the same in the present invention.

The solvent used in the aqueous ink used in the present invention is water or a mixed solvent of water and a water-soluble organic solvent.
Particularly preferred is a mixed solvent of water and a water-soluble organic solvent, which contains a polyhydric alcohol having an effect of preventing ink from drying as a water-soluble organic solvent.

The ink jet recording method for applying the above-mentioned ink to the recording medium to perform the recording may be a method in which the ink is effectively released from the nozzles and the ink is applied to the recording medium which is a projectile. Any method may be used. In particular, according to the method described in Japanese Patent Application Laid-Open No. 54-59936, the ink undergoes a sudden change in volume under the action of thermal energy, and the ink is ejected from the nozzles by the action force due to this state change. Can be used effectively.

Since the image formed matter immediately after printing contains water or a water-soluble organic solvent of the solvent used in the ink, it is preferable to remove these. Examples of the removing method include heating, decompression, and blowing of a dry gas, and a combination of a plurality of these methods may be performed.

When the outermost layer 3 is provided, the recording medium of the present invention is heated after image formation to make the porous outermost layer 3 nonporous. As a method for making nonporous, heat treatment is preferable, and by performing such treatment, water resistance, weather resistance such as light resistance become good, and glossiness can be imparted to an image,
Enables long-term storage of printed matter. In the present invention, since the lower ink receiving layer also contains a thermoplastic resin, the outermost surface layer is more securely adhered to the lower layer by welding with the resin, and the durability is improved. It can be applied to any use.

The heating temperature at this time has a relationship with time in consideration of the influence on the material such as the base material, the ink receiving layer and the ink, and the surface properties after nonporous formation.
Is preferable.

In the case where the base material is a material having a low softening point, such as a vinyl chloride resin, as described above, the base material starts to deform when the heating temperature exceeds 60 to 70 ° C. Therefore, in the present invention, when such a substrate is used, the entire medium is not heated, and is not in contact with a heat source, and only the surface is irradiated with heat rays such as infrared rays to the outermost layer and the outermost layer. It is preferable to heat only the surface layer of the adjacent ink receiving layer. It is not preferable to bring the heat source into contact with the recording medium because the surface shape of the heat source is transferred to the surface of the thermoplastic resin to reduce the gloss and that the transfer of heat to the substrate cannot be controlled.

[0055]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

As a recording method on a recording medium, a bubble jet color printer BJC-620J manufactured by Canon Inc. is used.
W was used. The printing mode was an OHP sheet mode.

(Example 1) First, alumina hydrate (sol) having a hairy bundle (ciliform) structure was synthesized as a pigment particle by a hydrolysis / peptization method of aluminum isopropoxide. To this, vinyl chloride particles (product name: G-351, manufactured by Zeon Corporation: vinyl chloride latex, film formation temperature: 100 to 110 ° C.) were added as thermoplastic resin particles. The weight ratio between the pigment particles and the thermoplastic resin particles was adjusted to be 100: 15. This coating liquid was applied to a surface of a white hard vinyl chloride resin plate having a magnetic stripe having a size of 500 mm × 500 mm and a thickness of 0.74 mm opposite to the magnetic stripe, and dried at 60 ° C. for 20 minutes. The thickness when dried was 40 μm. This was sandwiched between flat ferro plates heated to 150 ° C., treated for 5 minutes while applying a pressure of 0.1 kg / cm ² , and then gradually cooled to 40 ° C. over 1.5 hours.

The above-mentioned vinyl chloride latex was applied using a wire bar to a thickness of 3 μm upon drying, and dried at 50 ° C. for 15 minutes. After that, 80.6m
mx 54.0 mm, square R was punched out to a size of 3.0 mm.

Then, ink jet recording was performed by using the above-described ink jet printer. However, the following pigment inks were used.

Ink composition: Black ink: Carbon black pigment 6 parts by weight Styrene-acrylic acid copolymer (neutralized monoethanolamine) 2 parts by weight Ethylene glycol 25 parts by weight Diethylene glycol 7 parts by weight Water 60 parts by weight

Yellow ink: Benzidine Yellow G pigment 4 parts by weight Styrene-acrylic acid copolymer (monoethanolamine neutralized product) 1.5 parts by weight Ethylene glycol 25 parts by weight Diethylene glycol 7 parts by weight Water 62.5 parts by weight

Magenta ink: quinacridone pigment 4 parts by weight Styrene-acrylic acid copolymer (monoethanolamine neutralized product) 1.5 parts by weight Ethylene glycol 25 parts by weight Diethylene glycol 7 parts by weight Water 62.5 parts by weight

Cyan Ink: Copper phthalocyanine blue pigment 4 parts by weight Styrene-acrylic acid copolymer (monoethanolamine neutralized product) 1.5 parts by weight Ethylene glycol 25 parts by weight Diethylene glycol 7 parts by weight Water 62.5 parts by weight

The printed PVC sheet was dried by heating at 60 ° C. for 30 minutes to remove the volatile solvent in the ink.

The recording medium has a heating section of 10 mm width × 200 m.
An m-length heater with a surface temperature of 210 ° C. was fed at a speed of 0.2 mm / SEC with a gap of 0.2 mm from the recording medium and heated to obtain an image-formed product. Almost no deformation of the recording medium was observed, and the outermost latex layer could be made nonporous.

The obtained image was clear and the coloring material did not fall off even when rubbed. Further, embossing was performed on this image-formed product, but no peeling of the ink receiving layer was observed. In addition, even after immersion in tap water for 100 hours, the ink receiving layer did not peel off, and no image disturbance or reduction in density was observed. In addition, no change in appearance was observed even when left in an atmosphere at 40 ° C. and a relative humidity of 90% for 50 hours.

Example 2 An image was formed in the same manner as in Example 1 except that the ink used in Example 1 was changed to the following. When evaluated in the same manner as in Example 1, the same results as in Example 1 were obtained.

Dye 5 parts by weight Ethylene glycol 15 parts by weight Polyethylene glycol 10 parts by weight Water 70 parts by weight Ink dye Y: C.I. I. Direct Yellow 86 M: C.I. I. Acid Red 35 C: C.I. I. Direct Blue 199 Bk: C.I. I. Food black 2

Example 3 Colloidal silica (product name, Snowtex ST-) was used as pigment particles for the receiving layer.
N: manufactured by Nissan Chemical Industries, Ltd.), and a card-type recording medium was obtained in the same manner as in Example 1.

An image was formed thereon using the pigment ink used in Example 1. Further, the same processing as in Example 1 was performed to obtain an image-formed product. Almost no deformation of the recording medium was observed, and the outermost latex layer could be made nonporous.

The obtained image was clear and the coloring material did not fall off even when rubbed. Further, embossing was performed on this image-formed product, but no peeling of the ink receiving layer was observed. In addition, even after immersion in tap water for 100 hours, the ink receiving layer did not peel off, and no image disturbance or reduction in density was observed.

Example 4 10 parts by weight of polyvinyl alcohol (trade name, PVA117: manufactured by Kuraray Co.), 0.5 parts by weight of boric acid (H3BO3) were added to 100 parts by weight of the solid content of the alumina hydrate of Example 1. 10 parts by weight of vinyl chloride particles (the same as in Example 1) were added to obtain a coating liquid.

This coating liquid was measured to have a size of 500 mm × 500 mm and a thickness of 0.74
A terephthalic acid-ethylene glycol-cyclohexane dimethanol copolymer (trade name: PETG, manufactured by Eastman Chemical Co.) with a magnetic stripe having a thickness of 1 mm was coated on the surface opposite to the magnetic stripe, and dried at 60 ° C. for 20 minutes. The thickness when dried was 40 μm. This was sandwiched between flat ferro plates heated to 130 ° C., treated for 5 minutes while applying a pressure of 0.1 kg / cm ² , and then gradually cooled to 40 ° C. over 1.5 hours.

The above-mentioned vinyl chloride latex was applied using a wire bar to a thickness of 3 μm when dried, and dried at 50 ° C. for 15 minutes. After that, 80.6m
mx 54.0 mm, square R was punched out to a size of 3.0 mm.

Using the pigment ink used in Example 1, an image was formed. Further, the same processing as in Example 1 was performed to obtain an image-formed product. Almost no deformation of the recording medium was observed, and the outermost latex layer could be made nonporous.

The obtained image was clear and the coloring material did not fall off even when rubbed. Further, embossing was performed on this image-formed product, but no peeling of the ink receiving layer was observed. In addition, even after immersion in tap water for 100 hours, the ink receiving layer did not peel off, and no image disturbance or reduction in density was observed.

(Example 5) 10 parts by weight of polyvinyl alcohol (trade name, PVA117: manufactured by Kuraray), 0.5 parts by weight of boric acid (H3BO3) were added to 100 parts by weight of the solid content of the alumina hydrate of Example 1. 10 parts by weight of vinyl chloride particles (the same as in Example 1) were added to obtain a coating liquid. The following operations were performed in the same manner as in Example 1 except that the outermost layer was not provided, and a card-type recording medium having only one ink receiving layer was obtained.

Using the pigment ink used in Example 1, an image was formed.

The obtained image was clear and the coloring material did not fall off even when rubbed. Further, embossing was performed on this image-formed product, but no peeling of the ink receiving layer was observed. In addition, even after immersion in tap water for 100 hours, the ink receiving layer did not peel off, and no image disturbance or reduction in density was observed. The color appearance changed somewhat, probably because of a little water, but it was practically acceptable. afterwards,
Dried and returned.

Comparative Example 1 A card-type recording medium was obtained in the same manner as in Example 1, except that the thermoplastic resin particles were replaced with polyvinyl alcohol.

Using the pigment ink used in Example 1, an image was formed. Further, the same treatment as in Example 1 was performed to make the outermost surface layer nonporous to obtain an image-formed product. Deformation of the recording medium was hardly observed, but the portion printed with the pigment ink was not sufficiently glossy because the outermost layer of the latex layer was not sufficiently nonporous. Further, embossing was performed on this image-formed product, and peeling of the ink receiving layer was partially observed.

(Comparative Example 2) The same operation as in Example 5 was carried out except that no vinyl chloride particles were added. A card type recording medium having only one ink receiving layer without an outermost layer was obtained.

An image was formed thereon using the pigment ink used in Example 1.

The obtained image was clear, but it was found that the coloring material partially fell due to rubbing and that the coloring material did not enter the ink receiving layer. Further, embossing was performed on this image-formed product, but no peeling of the ink receiving layer was observed. Further, embossing was performed on this image-formed product, and peeling of the ink receiving layer was partially observed.

[0085]

As described above, according to the present invention,
A card-type recording medium on which personal information is easily and neatly printed by ink jet recording can be obtained at low cost. Further, the image of the obtained card is excellent in water resistance, and is stable even if left for a long time in a high-temperature, high-humidity environment, and does not deteriorate. In addition, the mechanical strength of the image surface can be obtained without any problem in practical use. Further, it can be used in combination with conventional digital recording such as magnetic or optical recording, screen printing, offset printing, embossing and the like.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a recording medium of the present invention.

FIG. 2 is a schematic sectional view showing another example of the recording medium of the present invention.

[Explanation of symbols]

 1 base material 2 ink receiving layer 3 outermost layer

Claims (12)

[Claims] 1. A recording medium having an ink receiving layer on at least one surface of a substrate, wherein the ink receiving layer is a porous layer containing pigment particles and thermoplastic resin particles welded to each other. . 2. The recording medium according to claim 1, wherein the ink receiving layer has a porous outermost layer containing thermoplastic resin particles. 3. The recording medium according to claim 2, wherein said substrate is of a card type. 4. The recording medium according to claim 1, wherein said pigment particles are alumina hydrate. 5. The recording medium according to claim 1, wherein said base material is a polyvinyl chloride resin. 6. The recording medium according to claim 1, wherein said base material is a polystyrene resin. 7. The recording medium according to claim 1, wherein said base material is polycarbonate. 8. The recording medium according to claim 1, wherein the base material is a terephthalic acid-ethylene glycol-cyclohexanedimethanol copolymer. 9. An image forming method, wherein an image is formed on the recording medium according to claim 1 by jetting ink by an ink jet recording method. 10. An image forming method according to claim 2, wherein an ink is jetted on the medium according to the ink jet recording method to form an image, and then the outermost layer is welded and made transparent. 11. The image forming method according to claim 8, wherein the coloring material of the ink is a pigment. 12. A step of applying a coating liquid containing pigment particles and thermoplastic resin particles to a substrate, and a step of applying heat under pressure to weld the thermoplastic resin particles to form an ink receiving layer. And a method for manufacturing a recording medium.