JPH08183243A - Material to be recorded - Google Patents

Abstract

PURPOSE: To obtain a material to be recorded suitable for ink jet recording capable of obtaining highly detailed image quality small in dot size by providing a resin layer containing alumina fine particles in critical pigment vol. concn. or less on a base material such as a transparent film. CONSTITUTION: In a material to be recorded enabling printing due to aq. ink such as ink jet recording, a resin layer containing alumina fine particles in critical pigment vol. concn. or less is provided at least on the single surface of a base material. Alumina fine particles may have any particle shape and all of feather like, columnar, spherical and lumpy shapes are suitably used and ones with a short diameter of 1μm or less are used. As alumina fine particles, alumina hydrate, boehmite, alumina fine particles having a boehmite type structure and an alumina sol stabilized by a nitrate ion, an acetate ion and a chloride ion are used. A hydrophilic resin being a resin soluble in water or alcohol is used in the resin layer in a non-crosslinked state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording material capable of printing with an aqueous ink such as ink jet recording.

[0002]

2. Description of the Related Art In recent years, the performance of graphics has been improved.
Sonar computers have become popular and it has become possible to easily create color charts. Various types of printers that can output color are commercially available.
Inkjet printers are widely used because they are low in purchase price and running cost and can obtain image quality of necessary and sufficient quality, and it is expected that demand will further increase in the future.

Paper is generally used as a recording material for color ink jet printers. However, printing is performed on a film for an over head projector, and a presentation, a lecture, a presentation, etc. are performed in color. The demand for wants is increasing. Since ink jet recording usually uses water-based ink, if a recording material for an electrostatic copying machine whose base material is a resin film such as an overhead projector film, the ink is It is not absorbed by the sheet at all, the ink is repelled, or the ink does not dry and it comes to a state where it can be removed by touch.

Therefore, in order to improve the absorptivity of the ink, a super absorbent resin or a water-soluble resin may be used in the surface layer (Japanese Patent Publication No. 64-5522, JP-A No. 60-224578).
No. 6-24493, etc.), or inorganic particles or organic particles may be mixed to make it porous (Japanese Patent Application Laid-Open No. 6-26242).
Nos. 1-244494, JP-A-60-219083, JP-A-57-14091 and JP-A-2-276670), and unevenness is provided on the surface to improve ink transfer (JP-A-SHO). 61-127386).

[0005]

However, the use of a highly absorbent resin, the addition of inorganic particles or organic particles, and the provision of irregularities on the surface do not allow the ink to ride practically and absorb the ink. However, there is a problem in that the ink tends to spread, the size of the dots becomes large, and high-definition image quality cannot be obtained.

In view of such circumstances, an object of the present invention is to provide a recording material having a small dot size and suitable for ink jet recording.

[0007]

The inventors of the present invention have conducted various studies to achieve the above object, and as a result, made specific inorganic particles contained in a specific concentration on a substrate made of a transparent film or the like. By providing a resin layer, it was found that a recording material having a small dot size and suitable for ink jet recording can be obtained, and the present invention has been completed.

That is, the present invention relates to a recording material characterized in that a resin layer containing alumina fine particles at a critical pigment volume concentration or less is provided on at least one surface of a substrate made of a transparent film or the like. .

[0009]

Structure / Operation of the Invention The alumina fine particles used in the present invention may have any particle shape, and any shape such as a feather shape, a column shape, a spherical shape, or a lump shape is preferably used. It is desirable that the diameter is minute in order to suppress the spread of dots, and the minor axis is 1 μm or less, especially 100 n
Those having a particle size of m or less are effective and have high transparency, and therefore are suitably used for a sheet for overhead projector.

As such alumina fine particles, alumina hydrate is easily available and the effect of the present invention is high, and therefore it is preferably used. A crystal structure having a boehmite or boehmite structure is easily available, and the effect of the present invention is high. Further, it is preferable that the alumina fine particles are uniformly dispersed in the resin, and from this point, it is effective to use alumina sol. Acid ions are usually used to stably disperse the alumina fine particles in the sol, but the acid ions may be those that do not adversely affect the resin for forming the resin layer, particularly nitrate ions, acetate ions, Alumina sol stabilized with chloride ions or the like is preferably used.

By the way, although the use of alumina fine particles has been proposed in the prior art such as Japanese Patent Laid-Open No. 2-276670, in these proposals, by using a large amount of alumina fine particles having a critical pigment volume concentration or more, it is possible to obtain a porous structure. A high quality resin layer is formed, and in this case, the dot size of the printing applied on the resin layer becomes large. this is,
It is presumed that, although the ink is quickly absorbed inside the porous resin layer, the ink penetrates in the lateral direction at the same time.

On the other hand, the present invention is characterized in that the alumina fine particles are used at a critical pigment volume concentration or less, and in this case, the resin layer formed is not porous as in the prior art. At the moment when the ink adheres to the surface, it forms small droplets with a relatively large contact angle and a small diameter, and is absorbed inside while suppressing lateral spread, so the dots formed are small. Conceivable.

In the present invention, the resin for forming the resin layer in which the fine alumina particles are dispersed is preferably a hydrophilic resin in order to absorb the solvent of the ink, and is dissolved in water or alcohol in an uncrosslinked state. A resin having such hydrophilicity is suitable. In ink jet recording, since water and higher alcohols are generally contained as the solvent of the ink, a resin having hydrophilicity that is soluble in both water and alcohol in the uncrosslinked state is more preferable.

Examples of such a hydrophilic resin include an amide group, a carboxylic acid group, a hydroxyl group, a sulfonic acid group, an amino group, a phosphoric acid group or salts thereof as a group for expressing hydrophilicity in the molecule. Alternatively, a resin having a polyethylene glycol chain is used. Among the above hydrophilic groups,
By introducing the amide group into the resin, it is possible to increase the affinity for both water and alcohol, and it is possible to obtain a resin that dissolves in both, so it is particularly preferably used. The amount of the amide group contained in the resin is preferably 1.5 mmol / g or more, more preferably 4 mmol / g or more, since the effect of absorbing the ink is not sufficiently exhibited when the amount is small.

A resin mainly having an amide group has a so-called substituted amide group in which the number of hydrogens directly bonded to nitrogen is 1 or less in that it has a strong affinity for both water and alcohol. Is good. The organic group bonded to the nitrogen atom in the substituted amide group is preferably a hydrocarbon group because it is easy to synthesize and can obtain appropriate hydrophilicity and hardness. The hydrocarbon group has 1 to 10 carbon atoms, and if it is larger than 10, the hydrophobicity becomes strong and the ink absorbency is lowered. The hydrocarbon group is preferably an alkyl group because the material is easily available and the effect is higher.

The resin mainly having an amide group can be synthesized by a method of polymerizing a monomer having an amide group or a method of generating an amide group by polycondensation. In the polymerization method, as the monomer having an amide group, an acrylamide derivative or a vinylpyrrolidone derivative can be obtained and easily synthesized,
Since the effect of ink absorption is sufficiently recognized, it is preferably used. Specific examples include dimethyl acrylamide, diethyl acrylamide, vinylpyrrolidone, etc., all of which are commercially available. In this polymerization method,
In order to improve various properties such as hardness, tackiness, fixability of dye, and crosslinkability of the resin layer, a monomer having no amide group
Or a monomer that does not form an amide group may be used in combination, and appropriate modification treatment may be performed after the polymerization.

Inorganic or organic fillers other than alumina fine particles may be added to the resin layer of the present invention to enhance ink absorbency and prevent interlayer adhesion. Inorganic fillers include silica fine particles or particles, alumina particles, etc., and organic fillers include acrylic resin, polystyrene, polyurethane, nylon, polyamide, polyethylene, polypropylene, epoxy resin, polyester, benzoguanamine resin, phenol resin, Examples include vinyl chloride resin and polyacrylonitrile. Although any of the fillers has an effect of preventing interlayer adhesion, the fine particles of silica have a high effect of absorbing ink, and colloidal silica and silica sol are preferably used. These other fillers tend to repel ink if too much, so
It is preferably 50% by weight or less, particularly 5 to 30% by weight.

Alumina fine particles,
In addition to the hydrophilic resin and the other inorganic fillers or organic fillers described above, various other substances may be incorporated as necessary. Examples thereof include antistatic agents, plasticizers, lubricants, dyes, pigments, dispersants, and resin components other than the above.

The resin layer composed of such components is usually 1 to 50 μm thick. This resin layer may be crosslinked, which further reduces the dot size,
Further, water resistance can be improved. Crosslinking includes epoxy group, double bond, oxazoline, isocyanate group, acid,
Functional groups such as acid chlorides, acid anhydrides and hydroxyl groups are used,
Having these functional groups in the resin component or in the crosslinking agent,
Crosslinking can be achieved by reacting them. When cross-linked in this way, the ink that has soaked can be removed by washing with water, moistening and wiping, wiping while applying a steam, and the like, so that the recording material can be reused. When the swelling ratio of the crosslinked resin layer is 1.5 times or more and the gel fraction is 50% or more, it is convenient for ink removal.

The recording material of the present invention is characterized in that the above-mentioned resin layer is provided on at least one side of the base material. Here, as the base material, any of the usual materials used for recording materials is used. Used. This is effective when a resin film having no ink absorbability is used as a base material, and in particular, a resin film provided on a transparent film is suitably used as a film for an overhead projector. This over
When used as a film for a head projector, all rays or a wavelength of 550 is used in order to ensure the visibility of the image.
It is preferable that the transmittance of the ray of nm is 75% or more.

[0021]

EXAMPLES Next, examples of the present invention will be described to explain more specifically. In the following, "parts" means "parts by weight".

Example 1 Dimethylacrylamide 76 parts Acrylic acid 14 parts Azobisisobutyronitrile 0.79 parts Isopropyl alcohol 126 parts Water 84 parts The above components were placed in a flask equipped with a condenser, and nitrogen was added. The mixture was reacted at 70 to 80 ° C. for 10 hours while stirring under an air stream. As a result, a 30% by weight solution of Resin A consisting of a copolymer of dimethylacrylamide and acrylic acid and having a number average molecular weight of 2.4 × 10 ⁴ was obtained.

To 10 parts of this resin A solution, a 20% by weight solution of alumina sol (Alumina sol-52 manufactured by Nissan Chemical Industries, Ltd.
0) 3 parts and 1.4 parts of water were added and mixed well to prepare a coating solution. This is coated on a polyethylene terephthalate film having a thickness of 100 μm and subjected to an easy-adhesion treatment (polyurethane treatment) with a No. 50 bar coater,
After drying at room temperature, a recording material having a resin layer containing alumina sol at a critical pigment volume concentration or less and having a thickness of about 6 μm was prepared.

Comparative Example 1 Alumina sol 20 was added to 1 part of the solution of Resin A obtained in Example 1.
Weight% solution (Alumina sol-520 manufactured by Nissan Chemical Industries, Ltd.)
7.5 parts and 9.5 parts of water were added and mixed well to prepare a coating solution. A recording medium having a resin layer containing alumina sol at a critical pigment volume concentration or higher was prepared in the same manner as in Example 1 except that this coating solution was used to coat with a No. 50 bar coater.

Example 2 10 parts of the resin A solution obtained in Example 1 was mixed with 2 parts of alumina sol.
0 wt% solution (Alumina sol-520 manufactured by Nissan Chemical Industries, Ltd.)
3 parts, trifunctional epoxy crosslinking agent (S manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.
R-GLG) (0.15 parts) and water (1.4 parts) were added and mixed well to prepare a coating solution. Using this coating solution, in the same manner as in Example 1, a recording material having a resin layer having a thickness of about 7 μm containing alumina sol at a critical pigment volume concentration or less on a polyethylene terephthalate film which has been subjected to an easy-adhesion treatment. Was produced. In this example, after coating on the film and drying, high temperature treatment was performed at 110 ° C. for 5 hours to crosslink the resin layer.

Comparative Example 2 1 part of the resin A solution obtained in Example 1 was mixed with 20 parts of alumina sol.
Weight% solution (Alumina sol-520 manufactured by Nissan Chemical Industries, Ltd.)
7.5 parts of trifunctional epoxy type crosslinking agent (SR-GLG manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.) and 9.5 parts of water were added and mixed well to prepare a coating solution. A recording material having a crosslinked resin layer containing alumina sol at a critical pigment volume concentration or more was prepared in the same manner as in Example 2 except that this coating solution was used to coat with a No. 50 bar coater. .

In order to investigate the performance of each recording material of Examples 1 and 2 and Comparative Examples 1 and 2, an ink jet printer (MJ-700V2 manufactured by Epson Corporation) was applied to each recording material.
In C), with the pattern of gray, the dots of cyan, magenta and yellow, and again with cyan, magenta and yellow,
The solid color of each black was printed, and the dot size, transparency and ink removability were evaluated in the following manner.
The results are shown in Table 1 below.

<Dot size> A magnified 50 times photograph of the gray pattern printed portion is photographed by an optical microscope (BH2 made by Olympus Co., Ltd.), and 10 short dots of cyan, magenta, and yellow are shown on the photograph. The diameter was measured with a ruler and the average was calculated.

<Transparency> The light transmittance at a wavelength of 550 nm was measured with an ultraviolet / visible spectrophotometer (200-20 type double beam spectrophotometer manufactured by Hitachi, Ltd.).

<Ink Removability> A recording material sample having a solid print of each color was immersed in tap water overnight, and the print densities before and after the solid print of each color were measured with a Macbeth densitometer (RD915 made by Macbeth). Then, the reduction rate of the concentration was obtained.

[0031]

[Table 1]

From the results shown in Table 1 above, the recording materials of Examples 1 and 2 of the present invention have a smaller dot size than the recording materials of Comparative Examples 1 and 2 which contain alumina fine particles at a critical pigment volume concentration or more. It can also be seen that it is small and has good transparency that can be used for overhead projectors. Further, in the recording material of Example 2 in which the resin layer is crosslinked,
It can also be seen that the ink can be removed and can be reused repeatedly.

[0033]

As described above, according to the present invention, it is possible to provide a recording material having a small dot size and suitable for ink jet recording by providing a resin layer containing alumina fine particles at a critical pigment volume concentration or less, Further, it is possible to provide a recording material that exhibits high transparency and can be repeatedly reused by crosslinking the resin layer.

Claims (20)

[Claims] 1. A recording material, characterized in that a resin layer containing alumina fine particles at a critical pigment volume concentration or less is provided on at least one surface of a substrate. 2. The recording material according to claim 1, wherein the alumina fine particles have a short diameter of 1 μm or less. 3. The recording material according to claim 1, wherein the fine alumina particles are hydrated alumina. 4. Alumina fine particles are beam mite or beam.
2. Alumina fine particles having a mitite structure.
The recording material described in [4]. 5. The recording material according to claim 1, wherein alumina sol is used as the alumina fine particles. 6. The recording material according to claim 5, wherein the alumina sol is an alumina sol stabilized with nitrate ions, acetate ions and chloride ions. 7. The recording material according to claim 1, wherein the resin layer contains a hydrophilic resin. 8. The recording material according to claim 7, wherein the hydrophilic resin is a resin which dissolves in water or alcohol in an uncrosslinked state. 9. The recording material according to claim 7, wherein the hydrophilic resin is a resin which is dissolved in both water and alcohol in an uncrosslinked state. 10. The hydrophilic resin is a resin having an amide group, a carboxylic acid group, a hydroxyl group, a sulfonic acid group, an amino group, a phosphoric acid group or a salt thereof, or a polyethylene glycol chain in the molecule. 7. The recording material according to 7. 11. The recording material according to claim 7, wherein the hydrophilic resin is a resin mainly having an amide group in the molecule. 12. The recording material according to claim 11, wherein the amide group is a substituted amide group. 13. The recording material according to claim 12, wherein the organic group bonded to the nitrogen atom in the substituted amide group is a hydrocarbon group. 14. The recording material according to claim 13, wherein the hydrocarbon group has 1 to 10 carbon atoms. 15. The recording material according to claim 13 or 14, wherein the hydrocarbon group is an alkyl group. 16. The recording material according to claim 11, wherein the resin mainly having an amide group in its molecule is a resin containing an acrylamide derivative or a vinylpyrrolidone derivative as a main component as a monomer. 17. The acrylamide derivative or the vinylpyrrolidone derivative is dimethylacrylamide, diethylacrylamide or vinylpyrrolidone.
6. The recording material according to item 6. 18. The recording material according to claim 1, wherein the resin layer is crosslinked. 19. The functional group used for crosslinking the crosslinked resin layer is an epoxy group, a double bond, an oxazoline, an isocyanate group, an acid, an acid chloride, an acid anhydride or a hydroxyl group. Item 18. The recording material according to item 18. 20. The recording material according to claim 1, wherein the base material provided with the resin layer is made of a transparent film.