JPH04147887A - Ink jet recording medium - Google Patents

Abstract

PURPOSE:To improve an ink absorbing speed and ink drying properties by a method wherein a layer containing a specific copolymer composition is provided on a substrate as an ink accepting layer. CONSTITUTION:An ink accepting layer contains a copolymer obtained by copolymerizing a monomer selected out of compounds I and a multifunctional vinyl monomer selected out of compounds II in ratios of 10 pts.wt. or more and 0.1-10 pts.wt. to all monomers, respectively. The copolymer is synthesized using water and an organic solvent having a miscibility with water. In the presence of polyvinyl alcohol or polyvinyl pyrrolidone in the system, the copolymer is produced in a fine particle form. The compounds I are p-styrene sulfonic acid, the alkali metal salt thereof, (meth)acryl amide, (meth)acrylic acid, the metal salt thereof or the neutralized salt thereof by an organic amine, 2- acrylamido-2-methylpropanesulfonic acid, and the alkali metal salt thereof or the neutralized salt thereof by an organic amine. The compound II are divinylbenzene, methylenebisacrylamide, ethylene glycol di(meth)acrylate, and vinyl ester of (meth)acrylic acid.

Description

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

The present invention relates to a recording medium for recording using water-based ink, and particularly to an inkjet recording medium suitable for color image recording using water-based ink using paper or film as a support.

[Prior art and its problems]

The inkjet recording method uses a variety of operating principles to eject a minute amount of ink onto the recording medium to print characters, letters, etc.
Because it is a device for recording images, etc., and has great flexibility in recording patterns and can be easily multicolored, it has rapidly become popular for various uses as a hard copy device for various shapes and color images, including kanji. There is. Furthermore, inkjet recording media for overhead projectors that use a translucent film as a support are used in many meetings, lectures, briefing sessions, and product promotions, etc., along with photo slides. There are many advantages to producing a recording medium using an inkjet recording method. Conventionally, efforts have been made in terms of equipment and ink composition to use high-quality paper or coated paper used for ordinary printing and writing as inkjet recording materials. However, as the performance of inkjet recording apparatuses increases, such as higher speeds, higher definitions, and full-color inkjet recording apparatuses, and their applications expand, more advanced characteristics are now required of recording media. That is, as a recording material, the density of ink dots is high;
The colors should be bright and vivid, the ink should be absorbed quickly and the ink should not run or smear even if the ink dots overlap, the lateral spread of the ink dots should not be unnecessarily large, and the periphery should be smooth. It is required that the image not be blurred. In order to solve these various demands, 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; This will largely depend on the properties of the resin formed on the 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. When an inkjet recording medium using such a hydrophilic resin is used for an overhead projector and 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 bleed. Currently, there are many problems such as drying properties, 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 that can be applied to both paper supports and transparent supports such as films. It is something. That is, in an inkjet recording medium that has at least one ink-receiving layer on a support such as paper or film and forms a recorded image using an aqueous ink containing a water-soluble dye, the ink-receiving layer contains all the monomers. contains a copolymer obtained by copolymerizing at least 10 parts by weight of a monomer selected from compound (1) and 0.1 to 10 parts by weight of a polyfunctional vinyl monomer selected from compound (II), and The copolymer is produced in the form of fine particles by using water and a water-miscible organic solvent during synthesis and by pre-existing polyvinyl alcohol or polyvinylpyrrolidone in the system. An inkjet recording material characterized in that it is obtained by. (Compound I) p-styrenesulfonic acid and its alkali metal salts, (meth)acrylamide, (meth)acrylic acid and its metal salts or neutralized salts with organic amines, 2-acrylamido-2-methylpropanesulfonic acid and its Neutralized salts with alkali metal salts or organic amines (compound II) Divinylbenzene, methylenebisacrylamide, ethylene glycol di(meth)acrylate, (meth)
The role of the acrylic acid vinyl ester compound (1) is that it is an essential component in imparting good hydrophilicity to the formed resin composition and increasing the absorption of aqueous ink. The role of compound (II) is to provide the resin composition with appropriate crosslinking points, giving it high water absorption ability,
It is an essential component in controlling the absorption rate of water-based ink and the spread of ink dots. The proportions of compounds (I) and (n) in the copolymer composition used in the present invention are at least 10 parts by weight of compound (I) and 0.0 parts by weight of compound (n). However, if the proportion of compound (I) 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. A copolymer synthesized by a combination of arbitrary monomers selected from compounds (I) and (n) has a crosslinked structure,
Synthesis in solution form is difficult in homogeneous solution polymerization using a normal aqueous medium. That is, in a system containing a relatively large amount of compound (n), the crosslinking reaction proceeds in parallel with the polymerization reaction, so the entire system often becomes gel-like and solidified before the polymerization is completed. Dry such a gel-like substance,
It is possible to use a powdered resin obtained by crushing it in a dispersed state, but if you try to apply it on paper or film and use it as an ink absorption layer, there will be no problem in terms of ink absorption speed, but Since the particle size of the powder is relatively large, the coating film thickness is not uniform, resulting in undesirable drawbacks such as uneven ink absorption and bleeding. Therefore, as a result of further intensive studies, the present inventors found that a more preferable resin is one that uses water and a water-miscible organic solvent as the medium used during polymerization, even if the copolymer composition is the same as the above polymer. It has been found that it is effective to prevent the entire system from gelling by synthesizing the resulting polymer in the form of fine particles or dispersion by precipitating it from the system using a mixed solvent. That is, the polymer obtained in this way is in a dispersed state during polymerization, but by removing the organic solvent or diluting it by adding water after polymerization, it can be dissolved uniformly or if the degree of crosslinking is low. can be made into a liquid that is stably dispersed in the form of fine particles. In order to form the resulting polymer into a dispersed state or fine particle form as described above, it is important to select a medium that is soluble in the medium in the monomer state, but becomes insoluble in the medium once the polymer is formed. Examples of such media include systems in which alcohols such as methanol, ethanol, and isopropanol are added to water, and mixtures in which water-miscible organic solvents such as water/dioxane, water/acetone, etc. are added. Particular preference is given to carrying out the polymerization using a solvent. 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, considering the ease of handling the organic solvent used,
Most preferred is the use of alcohol. Furthermore, when performing polymerization in the system described above, by adding a resin that is soluble in the medium to the system before the start of polymerization, it is possible to stably precipitate the resulting polymer in the form of fine particles. . 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 preferably 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. . When such a resin is added to the system in advance and polymerized, the resulting polymer is often obtained as a stable fine particle dispersion, and it can be applied as a coating liquid onto a support in this state. However, if the organic solvent used is eluted from the system or diluted with water, it is also possible to obtain a coating liquid that is uniformly dissolved or stably dispersed if the degree of crosslinking is high. . The resin composition according to the present invention basically consists of a compound (I
It is composed of a copolymer obtained by copolymerizing two or more monomers selected from compounds (I) and (II). It is also possible to form polymers. Alternatively, it is also possible to introduce a third component monomer as a monomer other than compounds (I) and (II) for various purposes. Such third 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 a quaternary salt thereof, styrene and its derivatives, vinyl acetate, maleic acid, crotonic acid, (meth)acrylonitrile, and others can be mentioned. 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 polymerization is completed, 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 polymers include
Various water-soluble polymers such as polyvinyl alcohol, polyvinylpyrrolidone, gelatin and its derivatives, hydroxyethylcellulose, methylcellulose, hydroxypropylcellulose, sodium and ammonium salts of carboxymethylcellulose, sodium polyacrylate, and starch can be used; In this case, it is preferable to use it in an amount of 100 parts by weight or less based on the total amount of all monomers constituting 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 manufacturing 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 copolymer resin composition according to the present invention is used alone or together with water-soluble polymers and other additives within a range that does not impair translucency, and is usually used as a coating solution. It can be manufactured by coating and drying using the following coating method. The dry film thickness of the ink-receiving layer formed in this way is preferably in the range of 3 to 12 microns, and in order to further improve the curling properties of the support, a similar resin layer or Layers made of other water-soluble polymers may also be formed.

【Effect of the invention】

By forming a layer containing the copolymer composition according to the present invention as an ink-receiving layer on a support, such a resin composition can be applied uniformly, and the highly hydrophilic portion and water absorption layer in the resin composition can be coated uniformly. Because it also contains a crosslinked component that greatly contributes to the properties of the ink, it provides a translucent film that has excellent ink absorption speed, excellent ink drying properties, and does not cause ink dot smearing, and is suitable for both supports such as paper and film. It can be applied to many areas, making it an excellent inkjet recording material using aqueous ink.

【Example】

The present invention will be explained in more detail below based on synthesis examples and examples, but the effects are not limited to these examples. (Synthesis Example 1) 80 g of sodium p-styrene sulfonate 1 polyvinyl alcohol (PVA103
, manufactured by Kuraray Co., Ltd.), 120 g of distilled water and 160 g of ethanol were added, and the mixture was dissolved at 75°C. 5 g of AIBNl was added under a nitrogen atmosphere, and 1.5 g of methylenebisacrylamide was added little by little over 1 hour, followed by heating and stirring at this temperature for 3 hours. The product is a white dispersion, which is added to water to reduce the solids content to 17
% homogeneous polymer solution was obtained. (Synthesis Example 2) Similarly to Synthesis Example 1, polyvinyl alcohol (PVA20
3. 10g of Sp-potassium styrene sulfonate (manufactured by Kuraray Co., Ltd.), 80g of acrylamide, and 130g of distilled water.
g, dissolved in 150 g of isopropanol, and adding 5 g of divinylbenzene dropwise over 2 hours.
Polymerization was carried out in the same manner at ℃ to obtain a white emulsion. Water was added to this to obtain a dispersion with a solid content of 17%. (Synthesis Example 3) In the same manner as Synthesis Example 1, take 7g of polyvinylpyrrolidone, 75g of acrylamide, 20g of sodium methacrylate, and 5g of styrene, add 150g of distilled water and 160g of isopropanol, and add 2g of ethylene glycol dimethacrylate h for 2 hours. 75℃ while dropping
Polymerization was carried out in the same manner to obtain a white emulsion. Thereafter, isopropanol was eluted under reduced pressure, and distilled water was further added to obtain a dispersion 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, 10 g of N,N-dimethylaminoethyl methacrylate hydrochloride, 2 methacrylic acid vinyl esters
Take 1 g and 35 g of polyvinyl alcohol, and add 1 g of distilled water.
50 g and 100 g of dioxane were added and polymerization was carried out in the same manner. After the polymerization was completed, dioxane was removed by distillation under reduced pressure, and water was further added to obtain a dispersion with a solid content of 17%. Example 1 Using high grade paper (basis weight 60 g/rr) with a Steckcht size degree of 0 seconds as a base paper, 100 parts of each of the resin solutions obtained in Synthesis Examples 1-4 and synthetic amorphous silica (Fine Seal X-
37B (manufactured by Tokuyama Soda Co., Ltd.) and 50 parts of the coating liquid was used as a coating liquid, and the solid content was
/nf and dried. After applying a super calender finish, each sample was used as an inkjet recording material on a Sharp inkjet printer 1.
When an image was recorded using 0-735, a good color image with no ink spreading or unevenness, high resolution, and no problems with ink absorption and drying properties was obtained. Example 2 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 samples had good transparency, and the ink absorption speed and ink drying performance were sufficiently fast. A good color image recording with high resolution and high color density 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 using an aqueous ink containing a water-soluble dye, the ink-receiving layer is composed of 10 parts by weight or more of a monomer selected from compound (I) and compound (II) based on the total monomers. It contains a copolymer obtained by copolymerizing at least 0.1 to 10 parts by weight of a selected polyfunctional vinyl monomer, and the copolymer contains water and a water-miscible organic solvent during its synthesis. use,
An inkjet recording medium characterized in that it is obtained by forming a copolymer in the form of fine particles by pre-existing polyvinyl alcohol or polyvinylpyrrolidone in the system. (Compound I) p-styrenesulfonic acid and its alkali metal salts, (meth)acrylamide, (meth)acrylic acid and its metal salts, or neutralized salts with organic amines, 2-acrylamido-2-methylpropanesulfonic acid and Its alkali metal salt or neutralized salt with organic amine (compound II) Divinylbenzene, methylenebisacrylamide, ethylene glycol di(meth)acrylate, (meth)
2. The inkjet recording medium according to claim 1, wherein the vinyl acrylate 2 and the water-miscible organic solvent are alcohol, acetone, or dioxane. 3. The inkjet recording medium according to claim 1 or 2, wherein polyvinyl alcohol or polyvinylpyrrolidone is used in an amount of 1 part by weight or more and 100 parts by weight or less based on the total monomers.