JPH04147886A - Ink jet recording medium - Google Patents

Abstract

PURPOSE:To obtain an ink jet recording medium superior in ink absorbing speed and ink drying properties and imparting a light-transmitting film preventing the bleeding of ink dots by a method wherein a layer containing a specific copolymer composition is provided on a substrate as an ink accepting layer. CONSTITUTION:An ink jet recording medium is provided with an ink accepting layer on a substrate. A recording image is formed on the ink accepting layer using aqueous ink containing a water-soluble dye. The ink accepting layer contains a copolymer obtained by copolymerizing a monomer selected out of compounds I and a monomer selected out of compounds II in ratios of 10 pts.wt. or more and 5-50 pts.wt. to all monomers, respectively. The compounds I are p-styrene sulfonic acid alkali metal salt, methacryl amide, methacrylic acid, the metal salt thereof or the neutralized salt thereof by an organic amine, 2-acryl amide-2-methyl propane sulfonic acid, and the alkali metal salt thereof or the neutralized salt thereof by an organic amine. The compound II are compounds shown by a general formula.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a recording medium on which recording is performed using aqueous ink, and particularly to a recording medium suitable for color image recording using aqueous ink using paper or film as a support.

[Prior art and its problems]

The inkjet recording method uses various operating principles to fly minute droplets of ink and attach them to the recording medium.
It is used to record images, etc., but because the recording pattern is flexible (and can be easily multicolored, it is rapidly being used for various purposes as a hard copy device for various figures including kanji and color images). Inkjet recording media for overhead projectors, which use transparent film as a support, are used along with photo slides in many meetings, lectures, information sessions, and product promotions. There are many advantages to producing recording media for overhead projectors using the inkjet recording method. Conventionally, as recording media for inkjet, the equipment and ink composition have been changed to use high-quality paper or coated paper used for ordinary printing and writing. However, as the performance of inkjet recording devices increases, such as higher speeds, higher definition, and full color, and the use of inkjet recording devices expands, more advanced characteristics are required of recording media. In other words, as a recording material, the ink dots must have a high density, the color tone must be bright (vivid), and the ink must be absorbed quickly so that the ink does not run or smudge even when the ink dots overlap. In order to solve these requirements, several proposals have been made in the past. For example, JP-A-53-49113
The issue discloses an inkjet recording paper in which a sheet containing urea-formalin resin powder is impregnated with a water-soluble polymer, but with this type of inkjet recording paper, the dot periphery tends to be blurred and the dot density is also low. It had the disadvantage of being low. Further, JP-A-55-5830 discloses an ink-jet recording paper in which an ink-absorbing coating layer is provided on the surface of the support, and JP-A-55-51583 discloses an amorphous pigment as a pigment in the coating layer. Another example of using silica powder was published in JP-A No. 5
No. 9-174381, No. 60-44389, No. 60-
No. 132785, No. 60-171143, etc. disclose inkjet recording sheets provided with transparent ink-receiving layers. Although these coated paper type inkjet recording media have been improved compared to regular paper type inkjet paper in terms of dot diameter, dot shape, and print density, they are still insufficient in terms of ink absorption speed. In particular, when multiple water-based ink dots overlap during high-speed multi-color recording, ink smearing may occur, and if the ink is not sufficiently dry, the ink may be transferred to the guide roller of the recording device, causing the recorded image to deteriorate. This could lead to problems such as contamination. On the other hand, regarding inkjet recording materials for overhead projectors using transparent supports, ink-absorbing inorganic pigments cannot be used in large quantities because they impede transparency, and the ink-absorbing properties are very low. It will depend on the properties of the resin formed on the loose transparent support. As resins conventionally used for such purposes, for example, JP-A No. 57-38185 discloses polyvinylpyrrolidone or polyvinylpyrrolidone-vinyl acetate copolymer, and JP-A No. 60-234879 discloses polyvinyl alcohol and olefin or A copolymer of styrene and maleic anhydride, JP-A-61-74879 discloses a cross-linked layer of ethylene oxide polymer and an isocyanate compound, JP-A-61-181679 discloses a copolymer of carboxymethyl cellulose and polyethylene oxide, JP-A-61-132377 discloses the use of a blend of methacrylamide grafted onto polyvinyl alcohol. Inkjet recording media using such hydrophilic resins are used for overhead projectors, and when the resin alone is formed as a layer on a transparent support within a range that does not impair transparency, the ink absorption speed is insufficient and the ink dots are At present, there are many problems such as bleeding, dryness or water resistance of recorded images, and surface stickiness. This is an inkjet that has excellent ink absorption, prevents ink dots from bleeding, and has excellent ink drying properties and excellent translucency, and can be applied to both transparent supports such as paper and film. At present, there is still no satisfactory recording material for use.

[Means to solve the problem]

The present invention solves various problems related to the present invention by using a resin composition with excellent transparency and high ink absorption ability, which can be applied to both transparent supports such as paper and film. be. That is, the present invention has at least one ink-receiving layer on a support such as paper or film,
In an inkjet recording medium in which a recorded image is formed on an ink-receiving layer using an aqueous ink containing a water-soluble dye, the ink-receiving layer contains compound (I) based on all monomers.
10 parts by weight or more of a monomer selected from
This inkjet recording material is characterized by its stiffness and contains a copolymer obtained by copolymerizing at least 5 to 50 parts by weight of a monomer selected from the following. (Compound I) Alkali metal salt of p-styrenesulfonic acid, (meth)acrylamide, (meth)acrylic acid and its metal salt or neutralized salt with organic amine, 2-acrylamido-2-methylpropanesulfonic acid and its alkali metal Salt or neutralized salt with organic amine (Compound ■) General formula % Formula % (In the formula, R1, R2 and R3 are hydrogen atoms or methyl groups, and n represents an integer from 1 to 3.) As the role of compound (I) is an essential component in imparting good hydrophilicity to the formed resin composition and increasing the absorption of aqueous ink. The role of compound (If) is to moderately reduce the water solubility of the copolymer produced by increasing this component, giving the film substantially the behavior of a partially crosslinked water-soluble polymer. Alternatively, when an epoxy compound or other crosslinking agent that reacts with the resin composition to form a crosslink is used in combination, the resin composition is given appropriate crosslinking points, giving it a high water absorption capacity, improving the absorption rate of water-based ink and improving the formation of ink dots. It is an essential component in controlling the spread. The proportions of compound (I) and (If) components in the copolymer composition used in the present invention are at least 10 parts by weight of compound (I) and 5 to 50 parts by weight of compound (U). If the proportion of (1) is less than 10 parts by weight, sufficient affinity for aqueous ink cannot be obtained, resulting in poor ink absorption. Furthermore, if the proportion of compound (If) is outside the above range, the ink absorption speed will be insufficient, causing problems such as bleeding in the image. When a copolymer synthesized by a combination of arbitrary monomers selected from compounds (I) and (n) contains a large amount of (n), the solubility of the resulting polymer in water decreases, and the entire system solidifies. Phenomenon 1 occurs, and synthesis in the form of a solution is difficult by homogeneous solvent polymerization using a normal aqueous medium. That is, when copolymerization is carried out in an aqueous solution in a system containing a relatively large amount of compound (4), the solubility of the resulting polymer in water decreases with the polymerization reaction, so that the entire system dissolves before the polymerization is completed. It often becomes gel-like and hardens. It is possible to dry and crush such a gel-like substance and use it in the form of a powdered resin dispersed, but if you try to use it as an ink absorption layer by coating it on paper or film Although there is no problem in terms of ink absorption speed, since the powder with a relatively large particle size is dispersed and used, the coating film thickness is not uniform, and there are undesirable drawbacks such as uneven ink absorption and bleeding. occured. Therefore, as a result of further intensive study, the present inventors found that
A more preferred resin is one in which the copolymer composition is the same as the above polymer, but by using a mixed solvent of water and a water-miscible organic solvent as the medium used during polymerization, the resulting polymer can be made into fine particles or dispersion. We have found that it is effective to prevent the entire system from gelling by synthesizing it in the form of precipitated from the system. That is, the polymer obtained in this way is in a semi-dissolved or dispersed state during polymerization, but by removing the organic solvent or diluting it by adding water after polymerization, it becomes a uniformly dissolved copolymer solution. You can. In order to form the resulting polymer into a semi-dissolved state, a dispersed state, or a fine particle state as described above, it is necessary to select a medium that is soluble in the medium in the monomer state, but becomes insoluble in the medium when the polymer is formed. is important, and examples of such media include systems in which alcohols such as methanol, ethanol, and isopropanol are added to water, and organic solvents that are miscible with water such as water/dioxane, water/acetone, and others. It is particularly preferable to carry out the polymerization using a mixed solvent to which . The mixing ratio of such organic solvent and water should be selected so as to at least substantially dissolve the monomer mixture before the start of polymerization and at least partially insolubilize the polymer formed during polymerization, and the minimum amount necessary. It is preferable to use Furthermore, from the viewpoint of ease of handling of the organic solvent used, it is most preferable to use alcohol or the like. Furthermore, when performing polymerization in the above system, by adding a resin that is soluble in the medium to the system before the start of polymerization, the resulting polymer can be kept in a dissolved state, semi-dissolved state, or fine particle state. It is possible to deposit stably. Examples of resins having such an effect include resins such as polyvinyl alcohol and polyvinylpyrrolidone, but there are no particular limitations on other resins as long as they are at least soluble in the medium used. The proportion of the resin that should be present in advance in such a system is desirably 100 parts by weight or less based on the total monomers used in the polymerization, and if it is used in excess of this, the effects of the present invention may be lost. be. If such a resin is added to the system in advance and polymerized, the resulting polymer may be obtained as a stable fine particle dispersion, and it can be applied as a coating liquid onto a support in this state. However, it is also possible to obtain a transparent coating liquid that is uniformly dissolved or stably dispersed by dissolving the organic solvent used from the system or diluting it with water. Alternatively, depending on the conditions, the produced polymer may be obtained in a substantially dissolved state, and it may be possible to use this state as a coating liquid. Furthermore, when the resin solution obtained as described above is applied onto a support, crosslinking that has the effect of reacting with the hydroxyl groups introduced into the copolymer by copolymerization of compound (II) and crosslinking the hydroxyl groups. By adding a curing agent such as a condensate of cyclic amide and glyoxal, a polyfunctional epoxy compound, an epichlorohydrin modified product of polyamide polyamine resin, or an amino-formaldehyde resin as an agent,
It is preferable because the coated film can be partially crosslinked, which can impart even higher water absorption to the film and also contributes to improving the water resistance of the film. The curing agent is not limited to the examples given here, but is not particularly limited as long as it is a crosslinking agent that is generally effective in crosslinking polymers having hydroxyl groups. The amount of such a curing agent used is preferably 1 part by weight or more and 40 parts by weight or less based on the total resin components in the coating liquid. If the amount used is more than this, the film will not be able to absorb the aqueous ink, so it is not preferable. The resin composition according to the present invention can basically be composed of two or more monomers selected from compounds (I) and (U), but may be composed of two or more monomers each selected from compounds (I) and (n). It is also possible to form a multi-component copolymer by selecting monomers. Alternatively, it is also possible to introduce a third component monomer as a monomer other than compounds (1) and (n) for various purposes. These third
The component monomers include those having various alkyl groups in the ester residue such as methyl (meth)acrylate, N, N
-dimethylaminoethyl (meth)acrylate and N
, N-diethylaminoethyl (meth)acrylate or their quaternary salts, styrene and its derivatives, vinyl acetate, maleic acid, crotonic acid, (meth)acrylonitrile, and others. Such a third component monomer can be used as necessary, but its proportion to the total monomers is preferably 40 parts by weight or less, and if it is used in excess of this, the effects of the present invention may not be achieved. May disappear. Further, after the completion of polymerization, various water-soluble polymers can be added to the coating liquid containing the copolymer for the purpose of improving film properties and other purposes. Such water-soluble resins include polyvinyl alcohol, polyvinylpyrrolidone, gelatin and its derivatives, hydroxyethylcellulose, methylcellulose, hydroxypropylcellulose, sodium salts and ammonium salts of carboxymethylcellulose,
Various water-soluble polymers such as sodium polyacrylate and starch can be used, but it is preferable to use them in an amount of 100 parts by weight or less based on the total amount of the copolymer resin composition obtained in the present invention. . Furthermore, for the purpose of improving image storage stability after inkjet recording, it is also possible to add ultraviolet absorbers, antioxidants, waterproofing agents, and the like. The method for producing the inkjet recording medium of the present invention includes:
When paper is used as a support, the copolymer resin composition according to the present invention alone or together with an ink-absorbing inorganic pigment and the like is used as a coating liquid, and is coated on the paper using a common coating device.
It can be formed by drying. In addition, when using a translucent support such as a film, the resin composition obtained by the present invention may be used alone or together with a water-soluble polymer or other additives to the extent that the translucency is not impaired, and the resin composition may be used as a coating liquid, and then applied by normal coating. It can be manufactured by coating and drying depending on the method. The dry thickness of the ink-receiving layer formed in this way is preferably in the range of 3 to 12 microns, and in order to improve the curling properties of the support, a similar resin layer or A layer made of a water-soluble polymer may also be formed.

【Effect of the invention】

By forming a layer containing the copolymer composition obtained in the present invention as an ink-receiving layer on a support, such a resin composition can be applied uniformly, and a highly hydrophilic portion can be formed in the resin composition. Since it also contains a crosslinked component that greatly contributes to water absorption, it provides a light-transmitting film that has extremely high ink absorption speed, excellent ink drying properties, and does not cause ink dot smearing. For this reason, it is applicable to both paper and film as a support.
It is an excellent inkjet recording material that uses water-based ink.

【Example】

Hereinafter, the present invention will be explained in more detail based on synthesis examples and examples, but the effects are not limited to these examples. (Synthesis Example 1) 85 g of sodium p-styrene sulfonate and 15 g of 2-hydroxyethyl methacrylate were placed in a 500 m 14 flask equipped with a stirrer, a thermometer, a nitrogen inlet tube, and a reflux condenser, and 100 g of distilled water and 18 g of ethanol were charged.
0g was added and dissolved at 75°C. AIB under nitrogen atmosphere
5 g of Nl was added, and the mixture was heated and stirred at this temperature for 3 hours. The product was poured into water to obtain a homogeneous polymer solution with a solids content of 17%. (Synthesis Example 2) Similarly to Synthesis Example 1, polyvinyl alcohol (PVA20
3. LogSp (manufactured by Kuraray Co., Ltd.) 70 g of potassium styrene sulfonate, 30 g of 2-hydroxyisopropyl methacrylate, 130 g of distilled water, 1 isopropanol
The polymer was dissolved in 50 g and polymerized in the same manner at 75°C to obtain a semi-dissolved polymer dispersion. After the polymerization was completed, water was added to obtain a uniform solution with a solid content of 17%. (Synthesis Example 3) In the same manner as in Synthesis Example 1, take 7g of polyvinylpyrrolidone, 75g of acrylamide, 20g of ethylene glycol monomethacrylate, and 5g of chloromethylstyrene, add 150g of distilled water, 160g of isopropanol, and polymerize in the same manner at 75°C. A white dispersion was obtained. After the polymerization was completed, isopropanol was dissolved out under reduced pressure, and distilled water was further added to obtain a uniformly dissolved aqueous solution with a solid content of 17%. (Synthesis Example 4) Same as Synthesis Example 1, 25 g of sodium methacrylate salt
, 35 g of potassium 2-acrylamido-2-methylpropanesulfonate, 15 g of 2-hydroxyisopropyl acrylate, 5 g of N-dimethylaminoethyl methacrylate hydrochloride, and 35 g of polyvinyl alcohol were added, 150 g of distilled water and 100 g of dioxane were added, and polymerization was carried out in the same manner. did. After the polymerization was completed, dioxane was removed by distillation under reduced pressure, and water was further added to obtain a uniform aqueous solution with a solid content of 17%. Example 1 High grade paper with Steckigt size degree 0 seconds (basis weight 60 g/nl"
) as base paper, 100 parts each of the resin solution obtained in Synthesis Example 1-4 and synthetic amorphous silica (Fine Seal
-37B, manufactured by Tokuyama Soda Co., Ltd.) was mixed with 50 parts as a coating liquid, and the solid content was reduced to 10 by using an air knife coater.
It was coated and dried to give a ratio of g/rrr. After applying a super calendar finish, images were recorded using an inkjet printer 10-735 manufactured by Sharp Corporation using each of the four types of samples as inkjet recording materials, and the results showed that there was no ink spread or unevenness, high resolution, and good ink absorption.
A good color image with no problems in drying was obtained. Example 2 In Example 1, resin solution 1 obtained in Synthesis Example 1-4
00 parts, 10 parts of a condensate of cyclic amide and glyoxal (Sanret 700M, manufactured by 5EQUA CHEM, Inc.) was added as a curing agent,
Furthermore, synthetic amorphous silica (Fine Seal X-37B)
Four types of coated paper were prepared in the same manner except that 50 parts of the coated paper was used as a coating liquid, and the printing was evaluated using an inkjet printer. As in Example 1, the ink absorption and drying properties were A color image with good print quality was obtained. Example 3 Each of the resin solutions obtained in Synthesis Examples 1-4 was individually applied onto a polyethylene film subjected to an aqueous subbing treatment to a dry film thickness of 5 microns, and dried. As in Example 1, each sample was used to record a color image using an inkjet printer 10-735 manufactured by Sharp Corporation. All four samples had good transparency, ink absorption speed, and ink drying properties. The process was sufficiently fast, and good color image recording with high resolution and high color density without image bleeding was obtained. Example 4 In Example 3, resin liquid 10 obtained in Synthesis Example 1-4
To 0 parts, 10 parts of a condensate of cyclic amide and glyoxal (Sunretz 700M) was added as a curing agent to prepare a coating liquid, but in the same manner as above, it was applied onto a polyester film, dried, and used as an inkjet recording material. evaluated. All four types of samples had similarly good ink absorption speeds and drying speeds, and good color image recording without image bleeding was obtained.

Claims (1)

[Claims] 1. Having at least one ink-receiving layer on the support,
In an inkjet recording medium in which a recorded image is formed on an ink-receiving layer using a water-based ink containing a water-soluble dye, the ink-receiving layer contains a compound (I
10 parts by weight or more of monomers selected from ) and compound (II)
An inkjet recording medium comprising a copolymer obtained by copolymerizing at least 5 to 50 parts by weight of a monomer selected from the following. (Compound I) Alkali metal salt of p-styrenesulfonic acid, (meth)acrylamide, (meth)acrylic acid and its metal salt or neutralized salt with organic amine, 2-acrylamido-2-methylpropanesulfonic acid and its alkali metal Neutralized salt with salt or organic amine (Compound II) General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (In the formula, R^1, R^2 and R^3 are hydrogen atoms or methyl groups, n is 1 to 3 2. The inkjet recording medium according to claim 1, wherein the copolymer is a copolymer formed in a fine particle form or a semi-dissolved form. 3. The inkjet recording according to claim 1 or 2, wherein the copolymer is copolymerized in a mixed solvent of water and a water-miscible organic solvent to form a fine particle or semi-dissolved copolymer. Medium. 4. The inkjet recording medium according to claim 1, 2 or 3, wherein the copolymer is a copolymer copolymerized in the presence of polyvinyl alcohol or polyvinylpyrrolidone. 5. The inkjet recording medium according to claim 4, wherein polyvinyl alcohol or polyvinylpyrrolidone is used in an amount of 100% by weight or less based on the total monomers. 6. The inkjet recording medium according to any one of claims 1 to 6, wherein the ink-receiving layer contains a curing agent capable of reacting with the hydroxyl group of the copolymer and curing the copolymer. 7. The curing agent is a condensate of cyclic amide and glyoxal,
7. The inkjet recording medium according to claim 6, wherein the inkjet recording medium is at least one selected from an epichlorohydrin-modified product of a polymamide polyamine resin, an amino-formaldehyde resin, and a polyfunctional epoxy compound. 8. The inkjet recording medium according to claim 6, 7 or 8, wherein the content of the curing agent is 1 to 40 parts by weight based on the total resin components in the ink receiving layer.