JP2000177236A - Water-base ink acceptable layer forming composition and water-base ink recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a highly clear image, enhance adhesiveness relative to a film, and avoid the occurrence of curls after film coating by preparing a water- base ink acceptable layer forming composition containing polyglyoxylic acid amide of a structural unit shown by a specific formula. SOLUTION: A water-base ink acceptable layer forming composition is prepared by blending polyglyoxylic acid amide of a structural unit shown by formula (both R1 and R2 show either a hydrogen atom or an organic group, simultaneously, they may be the same or different). Furthermore, coating liquid consisting of this composition is applied and then dried on a support body to provided a water-base ink acceptable layer, thereby forming a water-base ink recording medium. The density of a solution at coating a water-base ink acceptable forming composition on a support body in a solution is tentatively made 5-50% with respect to the whole weight of a solution, and a drying temperature during coating is suitable to be 50-200 deg.C, more suitably, to be 70-150 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition for forming an aqueous ink receiving layer and a recording medium for aqueous ink. Examples of the recording medium for aqueous ink include an inkjet recording sheet.

[0002]

2. Description of the Related Art Conventionally, aqueous ink-based recording media include, for example, polyvinyl pyrrolidone (PVP), polyvinyl alcohol (PVA), polyethylene oxide (PEO), methyl cellulose (M
A hydrophilic organic polymer such as C), hydroxypropylcellulose (HPC), carboxymethylcellulose (CMC) and starch is coated and used as an ink receiving layer. Among them, P which has relatively good performance for so-called high-grade grades such as glossy film and glossy paper
VP and PVA are mainly used.

Meanwhile, among water-based ink recording media, a color image formed by an ink-jet method can provide a recording comparable to multicolor printing by a plate making method or printing by a color photographic method. In applications where the number of copies is small, it is being widely applied because it is less expensive than the plate making method and the color photographic method. Recently, an application field of an inkjet printer that has been particularly noticed is an advertising application field generally called a wide format. The glossy paper and the glossy film described above are used in this advertising application, and in this field, sharpness of a printed image is most important.

However, the above-mentioned polymer alone does not sufficiently fix the dye at the time of printing, and the dye diffuses at the time of printing, resulting in insufficient image clarity. Tends to occur.

As a means for solving this problem, it has been attempted to add a low molecular weight cationic component such as a phosphonium compound (Japanese Patent Application Laid-Open No. 7-1830) or a cationic surfactant (Japanese Patent Application Laid-Open No. 10-278419). However, under high temperature and high humidity, low molecular components still migrate,
Further, a plurality of additives such as the addition of a crosslinking agent are required. Usually, the addition of the cross-linking agent is performed immediately before the application of the water-soluble resin, so that the coating operation is increased by one step, which is disadvantageous in terms of productivity.

On the other hand, an example in which an amine polymer containing an amino group or the like is used as a fixing agent for a dye is disclosed in Japanese Patent Application Laid-Open No.
266689 and JP-A-9-99630. However, many of these amine polymers are specially disadvantageous in terms of cost in practical use, and often lack versatility.

[0007] Further, PVP and PVA have low adhesion to the film, requiring special treatment on the film surface, and PVP has the disadvantage that the sheet applied to the film is easily curled.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has high printing performance,
In particular, it is an object of the present invention to provide a recording medium for aqueous ink and a resin composition for forming an aqueous ink-receiving layer used for the same, which can provide an image with particularly high sharpness, and have low adhesion to a film and curl even after coating on the film. I do.

[0009]

As a result of repeated studies, the present inventors have found that when a resin containing a glyoxylic acid-based polymer is used for the ink receiving layer, a water-based ink recording medium that solves the above problems can be obtained. And completed the present invention.

That is, the present invention provides the following general formula (1):

[0011]

Embedded image

(However, R ¹ and R ² both represent a hydrogen atom or an organic group, and may be the same or different at the same time.) Polyglyoxylic acid having a structural unit represented by The present invention relates to a composition for forming an aqueous ink receiving layer comprising an amide.

The polyglyoxylate is hydrophilized by amidating some or all of the ester groups in the side chains of the polyglyoxylate with an amine or the like, so that the balance with water resistance can be adjusted.

Another aspect of the present invention relates to a recording medium for aqueous ink having an aqueous ink receiving layer formed by forming the composition on a support.

It is not clear why the recording medium for aqueous ink of the present invention exhibits excellent effects. However, since the polymer has an amide group in the molecular chain, it is easy to adsorb the dye molecules, and the low molecular dye adsorbent is used. Thus, it is considered that a clear image with little bleeding over time was obtained without migration, and the adhesion to the film was also improved. It is presumed that the polymer used has a glass transition temperature of room temperature or lower, which suppresses curling by forming a flexible ink-receiving layer.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The composition for forming an aqueous ink receiving layer of the present invention is characterized by comprising a polyglyoxylic amide having a structural unit represented by the above general formula (1).

The polyglyoxylic acid amide includes:
Examples thereof include polyglyoxylic acid amide, a polymer in which a part of polyglyoxylic acid ester is amidated, and a mixture thereof.

The molecular weight of the polyglyoxylic acid amide, expressed as the peak molecular weight by GPC, is usually in the range of 5,000 to 1,000,000, preferably 10,000 to 200,000.

The polyglyoxylic acid amide can be obtained, for example, by amidating a polymer containing a polyglyoxylic acid ester.

The polyglyoxylate is obtained, for example, by polymerizing a monomer containing the desired glyoxylate.

As the glyoxylate, those having an ester group of 1 to 20 carbon atoms are usually used.
For example, glyoxylic acid methyl ester, glyoxylic acid ethyl ester, glyoxylic acid n-propyl ester, glyoxylic acid isopropyl ester, glyoxylic acid n-butyl ester, glyoxylic acid isobutyl ester are considered. These may be used alone or in combination of two or more.

Examples of the monomer include glyoxylic acid; glyoxylates such as ammonium glyoxylate and sodium glyoxylate; glyoxylamide; N-methylglyoxylamide; N-ethylglyoxylamide; N-
Glyoxylic acid N-substituted amides such as dimethylglyoxylamide, N-hydroxyethylglyoxylamide, and N-pyrrolidylglyoxylamide may be contained. One or more of these monomers may be used.

It may also contain other known copolymerizable monomers.

The polymerization method is not particularly limited, but it can be obtained, for example, by known anionic polymerization or cationic polymerization.

In the obtained polyglyoxylate, a chemically stable group may be introduced at a terminal for stabilizing the polymer. The group to be introduced is not limited, and examples thereof include an alkyl group such as a methyl group and an ethyl group; a cyclic alkyl group such as a cyclohexyl group; an alkoxy group such as a methoxy group and an ethoxy group; a cyclic alkyl group containing oxygen; In order to introduce a stable group, for example, epoxides such as ethylene oxide and propylene oxide;
Cyclic ethers such as 3-dioxolan and 1,4-butanediol formal; alkyl vinyl ethers such as ethyl vinyl ether and butyl vinyl ether; propylene;
substituted olefins such as n-vinyl-2-pyrrolidone; alcohols such as methanol and butanol; alkyl halides such as methyl iodide and tert-butyl chloride; allyl halides such as allyl chloride; acetals such as acetaldehyde dimethyl acetal; A method of reacting a compound such as alkyl sulfate such as dimethyl and diethyl sulfate; benzyl halide such as benzyl chloride;

The amidated polyglyoxylate can be obtained, for example, by amidating a part or all of the ester group of the polyglyoxylate (I) with a known amidating agent. The ratio of amidation can be arbitrarily adjusted according to the charging ratio of the amidating agent.
One or more amidating agents are used.

By amidating the ester group of the polyglyoxylate, the hydrophilicity, that is, the ink absorbency, the solubility in a solvent such as water, the compatibility with a known polymer, the additive or the mixture are improved. Physical properties such as improvement in adhesiveness and adsorptivity at the interface with, and further introduction of reaction points can be performed. Alternatively, in terms of safety, for example, the polymer can be made water-soluble by amidation with methylamine or the like, and drying and the like during coating can be performed safely.

Examples of the amidating agent to be used include ammonia; various amines such as alkylamine, alkanolamine, mercaptoamine, amino acid, amino acid anhydride, cyclic amine and polyamine. By using one or more of these amidating agents, hydrophilicity and dye-adsorbing property required for ink absorption can be exhibited.

When the alkylamine is reacted, the hydrophilicity of the polymer can be adjusted according to the length of the alkyl group. Specifically, methylamine, ethylamine, n
-Primary amines such as propylamine and amylamine; and secondary amines such as diethylamine and dibutylamine. Among them, methylamine, dimethylamine, ethylamine, and ethanolamine are particularly preferable from the viewpoint of imparting hydrophilicity.

Further, it is possible to introduce a functional group other than an ester by reacting a functional group-containing amine. For example, alkanolamines include monoethanolamine, diethanolamine and the like. Examples of the mercaptoamine include 2-aminoethylmercaptan and dimercaptoethylamine. Of these, monoethanolamine and diethanolamine are preferred in terms of imparting hydrophilicity.

Examples of the amino acid include glycine and glutamic acid, and examples of the amino acid anhydride include glycine anhydride.

In order to impart rigidity to the main chain, it is effective to introduce a cyclic amine such as pyrrolidine or morpholine. Of these, pyrrolidine is preferred, particularly in terms of imparting hydrophilicity.

To crosslink the polymer for the purpose of improving the water resistance, a polyvalent amine such as ethylenediamine,
It is effective to introduce hexamethylene diamine or the like. Alternatively, after amidation with an amine having an unsaturated bond such as allylamine, cross-linking is possible by irradiating the sheet surface with UV.

The ratio of amidation is dependent on the composition of the polymer or the type of amidating agent, and cannot be specified unconditionally. For example, in the case of a homopolymer obtained by homopolymerizing methyl glyoxylate, methylamine is added to the amidating agent. When used, at least 10% based on ester groups in the total amount of polymer
By amidating the degree, it is possible to efficiently absorb the aqueous ink, and it is more preferable that the amount is 30% or more. If the amidation ratio is 10% or less, the ink absorption speed may be low, and in extreme cases, the ink may not be absorbed.

The amidation reaction is usually carried out without a solvent or in water or an organic solvent. The solvent is preferably an inert solvent. The reaction temperature is preferably from -10 to 150C. If the temperature is lower than −10 ° C., the reaction rate may decrease, or the solidification or the viscosity may increase, which may make handling difficult. The amidation of the polyglyoxylate may be carried out after isolating the polyglyoxylate (I), or directly during or after the polymerization.

The composition for forming an aqueous ink receiving layer of the present invention can be mixed with a polymer other than polyglyoxylic acid. The polymer to be mixed is not particularly limited,
If it can be uniformly mixed with the glyoxylic acid-based polymer in appearance, it can be either hydrophobic or hydrophilic. Examples of the hydrophobic polymer include polyolefins such as polyethylene and polypropylene; halogens such as polyvinyl chloride; acrylics; polyamides such as nylon 6, and the like. Examples of the hydrophilic polymer include polyvinyl alcohols; polyethers such as polyethylene oxide and polydioxolane; celluloses such as methylcellulose and carboxymethylcellulose; and proteins such as polyaspartic acid.

In the case of mixing with a hydrophobic polymer, for example, when the writing property of an aqueous pen is required, the ratio of the polyglyoxylic acid-based polymer to the total polymer after mixing is 1%.
It is preferably at least 0% by weight. Further, in a recording medium that uses a relatively large amount of ink such as an ink jet and requires an ink absorption speed, the content is preferably 30% by weight or more, and more preferably 50% by weight or more.

When mixed with a hydrophilic polymer, for example,
For the purpose of improving the dye adsorption, the ratio of the polyglyoxylic acid-based polymer to the total amount of the polymer after mixing is 5%.
% Is preferable. For a material such as polyvinylpyrrolidone which has an amide group but has poor adhesion to a film such as PET, it is effective in improving the adhesion to a film. In this case, the ratio of the glyoxylic acid-based polymer to all the polymers is preferably 1% by weight or more.

In the present invention, the method of mixing the glyoxylic acid-based polymer with the other polymer is not particularly limited, and examples thereof include a method of melt-mixing and a method of mixing with a solution.

The composition for forming an aqueous ink receiving layer of the present invention contains a dye fixing agent, a pigment, a dispersant, a thickener, a pH adjuster, as long as the performance as a recording medium for aqueous ink is not impaired.
It can also contain a lubricant, a flow modifier, a surfactant, an antistatic agent, an antifoaming agent, a foam inhibitor, a release agent, a penetrant, a fluorescent brightener, an ultraviolet absorber, an antioxidant, and the like.

When the aqueous ink receiving layer forming composition of the present invention is coated on a support with a solution, the solid content concentration of the solution is not particularly limited as long as the composition can be formed on the support. However, for example, the standard is 5 to 50% based on the total weight of the solution. If it is less than 5%, the coating amount must be increased in order to obtain a sufficient thickness of the ink receiving layer, and it is not economical because much time and energy are required for drying.
On the other hand, if it exceeds 50%, the viscosity may be too high and the coatability may be reduced. Therefore, a concentration of 5 to 50% is preferably used.

The drying temperature during coating is preferably from 50 to 200 ° C., more preferably from 70 to 150 ° C. The drying time at that time depends on the solid content concentration of the coating liquid and the amount of coating. For example, when a solution of about 20% is dried at 100 ° C., 1 minute to 10 minutes is a standard.

The recording medium for aqueous ink of the present invention has an aqueous ink receiving layer obtained by forming the above-described composition for forming an aqueous ink receiving layer on a support.

The thickness of the ink receiving layer formed using the composition is preferably 1 to 50 μm. If it is less than 1 μm, the water content of the ink cannot be sufficiently absorbed, and a clear image cannot be obtained. On the other hand, when the thickness is 50 μm or more, the sheet is easily curled at the time of drying after application, and a remarkable improvement in printing performance cannot be expected.

The support is not particularly limited, but paper, synthetic paper, white film, transparent film and the like can be used. As paper, high quality paper, medium quality paper, art paper, coated paper, cast coated paper, foil paper, kraft paper,
Impregnated paper, vapor-deposited paper and the like can be used as appropriate. In addition, as the film and sheet, a flexible, high-strength, high-gloss polyethylene terephthalate, polyimide, polycarbonate, polyacetate, polyethylene, polypropylene, or the like can be used to improve the strength of the ink receiving layer. It is also possible to perform corona discharge treatment and various undercoat treatments.

The method for forming the ink receiving layer using the composition solution includes spin coating, roll coating, blade coating, air knife coating, gate roll coating, bar coating, size pressing, spraying, and the like. The recording medium of the present invention is obtained by coating the support by a method such as a coating method, a gravure coating method, a curtain coating method, a rod blade coating method, a lip coating method, a slit die coating method, and drying with a hot air dryer or the like. Can be

The aqueous ink recording medium thus obtained can be used for ink-jet printing, flexographic printing,
It can be used for all types of printing, such as gravure printing, offset printing, and projection printing.

[0048]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples.

(Synthesis Example 1) 90 g of acetonitrile, 5 μl of pyridine and 66 μl of ethylene glycol were previously added to a 300-ml pressure-resistant reaction vessel, and polymerization was carried out while adding 24 ml of distilled and purified methyl glyoxylate over about 30 minutes. After aging for 1 h, 126 μl of BF ₃ O
Et ₂ was added. 10.6 g of ethylene oxide was added in stages, paying attention to the exotherm. The reaction was carried out for 3.5 hours while maintaining the internal temperature at 35 ° C. After 1.4 g of triethylamine was added to neutralize BF ₃ OEt ₂ , the reaction solution was poured into ethanol. After removing the ethanol,
It dried under reduced pressure for 0 hours. The yield after purification was 78%, and the apex molecular weight measured by gel permeation chromatography was 24,000. 2 of the obtained polymers
13. dissolve 0 g in 81 g 1,3-dioxolane;
61 g of a 70% aqueous solution of ethylamine was added and reacted for 12 hours. ¹ H-NMR confirmed that the reaction was quantitative. The reaction solution was dried under reduced pressure at 50 ° C. for 10 hours to obtain a polymer (1) having an amidation ratio of 100%.

(Synthesis Example 2) At the time of amidation, 7.31 g
The reaction was carried out in exactly the same manner as in Synthesis Example 1 except that a 70% aqueous solution of ethylamine was used. The polymer (2) having a vertex molecular weight of 21,000 measured by GPC and an amidation ratio of 50% was obtained.
I got

(Synthesis Example 3) During amidation, 2.93 g
The reaction was carried out in exactly the same manner as in Synthesis Example 1 except that a 70% aqueous solution of ethylamine was used. The polymer (3) having a vertex molecular weight of 22,000 as measured by GPC and an amidation ratio of 20% was obtained.
I got

(Synthesis Example 4) At the time of amidation, 7.31 g
70% aqueous solution of ethylamine followed by 6.90 g of 28
% By reaction with the same procedure as in Synthesis Example 1 except that the reaction was carried out using aqueous ammonia, the peak molecular weight measured by GPC was 22,000, and the amidation rate was 100% (ethylamide 5
(0% and 50% amide).

(Synthesis Example 5) At the time of amidation, 1 was added to the solvent.
Using a 3-dioxolane / methanol mixed solvent, 1.3
The reaction was carried out in exactly the same procedure as in Synthesis Example 1 except that the reaction was carried out using 0 g of allylamine and then 15.85 g of 40% methylamine, and the apex molecular weight measured by GPC was 2
3000 (Polyamide (10% allyl amide and 90% methyl amide) 90%) was obtained as a polymer (5).

Example 1 A polymer (1) amidated with ethylamine and having an amidation ratio of 100% was dissolved in 1,3-dioxolane to obtain a polymer solution having a solid content concentration of 20%, and a bar coater (# 40) was used. The composition was applied on a PET film and dried with a hot air drier at 105 ° C. for 7 minutes to obtain a recording sheet for aqueous ink.

(Example 2) A polymer (2) amidated with ethylamine and having an amidation ratio of 50% was applied in the same manner as in Example 1 to obtain a recording sheet for aqueous ink.

Example 3 A polymer (3) amidated with ethylamine and having an amidation ratio of 20% was applied in the same manner as in Example 1 to obtain a recording sheet for aqueous ink.

(Example 4) A polymer (4) amidated with two kinds of ethylamine and ammonia and having an amidation ratio of 100% was applied in the same manner as in Example 1 to obtain a recording sheet for aqueous ink. .

(Example 5) A polymer (5) amidated with two kinds of methylamine and allylamine and having an amidation rate of 100% was dissolved in a 1,3-dioxolane / methanol mixed solvent to give a polymer having a solid content of 20%. A solution was applied on a PET film using a bar coater (# 40),
The resultant was dried with a hot air drier at 7 ° C. for 7 minutes to obtain a recording sheet for aqueous ink.

Example 6 10 parts of a polymer (1) amidated with ethylamine and having an amidation ratio of 100% and 10 parts of polyvinyl alcohol (PVA205, manufactured by Kuraray Co., Ltd.)
The polymer solution was dissolved in deionized water to obtain a polymer solution having a solid content of 20%, applied on a PET film with a bar coater (# 40), and dried at 105 ° C. for 7 minutes with a hot air drier to obtain a recording sheet for aqueous ink. .

(Example 7) 10 parts of a polymer (1) amidated with ethylamine and having an amidation ratio of 100% and 10 parts of polyvinylpyrrolidone (K-90, manufactured by ISP) were dissolved in deionized water to obtain a solid content concentration. 20% polymer solution,
Apply on a PET film with a bar coater (# 40)
It was dried with a hot air drier at 105 ° C. for 7 minutes to obtain a recording sheet for aqueous ink.

Comparative Example 1 Polyvinyl alcohol (PV
A205, manufactured by Kuraray Co., Ltd.) was dissolved in deionized water to obtain a polymer solution having a solid concentration of 20%, and a bar coater (# 4) was used.
0) was applied on a PET film and dried with a hot air drier at 105 ° C. for 7 minutes to obtain a recording sheet for aqueous ink.

Comparative Example 2 Polyvinylpyrrolidone (K-
90, manufactured by ISP Co., Ltd.), dissolved in deionized water to obtain a polymer solution having a solid content of 20%, applied on a PET film with a bar coater (# 40), and dried with a hot air drier at 105 ° C. for 7 minutes. A recording sheet for aqueous ink was obtained.

The recording sheet for aqueous ink obtained as described above was printed using a color ink jet printer (PM-750C manufactured by Epson), and the following items were evaluated. The results are shown in Table 1.

Curling The curl of the dried sheet was visually evaluated.

：: No curl.

Δ: There is a slight curl, but there is no problem in printing.

X: The sheet is curled in a tubular shape and printing is difficult.

Tack The surface tack of the aqueous ink sheet left at room temperature for 24 hours or more was evaluated.

：: No tack at all.

Δ: There is some tack, but it does not hinder use.

X: The tack is large and printing is not possible.

Printability After printing, bleeding and image clarity were visually evaluated.

○: A clear image without blur is obtained.

Δ: Although slightly inferior in sharpness, there is no bleeding and use is not hindered.

×: Both bleeding and sharpness are poor.

Adhesion The adhesion between the ink receiving layer and the PET film was evaluated by strongly rubbing the ink receiving layer with a finger.

○: No peeling at all.

Δ: Partial peeling depending on the rubbing method.

×: The entire ink receiving layer was peeled off from PET.

[0080]

[Table 1]

As is evident from Table 1, in Examples 1 to 7, a water-based ink recording sheet having no curling and excellent in printability and adhesion was obtained. In Examples 1 to 3, a slight decrease in printability was observed with a decrease in the amidation rate, but this was due to a slight decrease in the ink absorption rate due to an increase in hydrophobicity, and a slight bleeding occurred. it is conceivable that. In general, the water resistance of the ink receiving layer is not particularly required for advertising use because it is overlaminated,
It is considered that the sheets of Examples 2 and 3 are preferable in applications where overlamination is not performed and water resistance is required. On the other hand, the sheets obtained in Comparative Examples 1 and 2 have no problem in tackiness and printability, but PVP is difficult to use especially in terms of curling, and both PVA and PVP are PET films in terms of adhesion. Peeling occurred between the ink and the ink receiving layer. However, the polymer of (1) is PVA,
In Examples 6 and 7 mixed with PVP, the above problem was completely eliminated.

(Example 8) 10 parts of a polymer (1) amidated with ethylamine having an amidation ratio of 100% and 90 parts of polyethylene (Lexlon L401, manufactured by Nippon Petrochemical Co., Ltd.) were mixed with LaboPlast manufactured by Toyo Seiki Seisakusho Co., Ltd. Mill R-30
The mixture was kneaded at 140 ° C. and 30 rpm for 3 minutes to obtain a resin composition. The obtained resin composition was applied at 140 ° C. and 300 kg using a 37 t press manufactured by Miura Press Co., Ltd.
A recording sheet for an aqueous ink was obtained by hot pressing at f / cm ² for 3 minutes.

When writing was performed on the obtained sheet with an aqueous pen, it was confirmed that writability was small enough to prevent the use of the sheet, although it was slightly repelled.

Comparative Example 3 Polyethylene (Lexlon L
401, manufactured by Nippon Petrochemical Co., Ltd.)
140 ° C, 300kgf / cm using a 7t press
A recording sheet for aqueous ink was obtained by a hot press method under the conditions of a few minutes.

When the obtained sheet was written with an aqueous pen, the ink was repelled and writing was impossible.

[0086]

According to the present invention, a recording medium for water-based ink having no curling or tackiness and excellent in adhesion and printability can be easily and efficiently obtained.

Claims (3)

[Claims] 1. The following general formula (1): (However, R ¹ and R ² represent either a hydrogen atom or an organic group and may be the same or different at the same time.) Including polyglyoxyamide having a structural unit represented by A composition for forming an aqueous ink receiving layer. 2. The composition for forming an aqueous ink receiving layer according to claim 1, wherein the polyglyoxylate is a polymer obtained by amidating a part or all of a polyglyoxylate. 3. A recording medium for aqueous ink having an aqueous ink receiving layer formed by forming the composition according to claim 1 on a support.