JPH11245508A - Material to be recorded for ink jet recording - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a good ink drying property, clearness of images, and surface glossiness by making use of a polyol consisting of a polyurethane elastomer with an ionen introduced in a molecule skeleton and a polyurethane elastomer obtained by reaction hardening polyisocyanate and a cross-linking agent. SOLUTION: A polyurethane elastomer is obtained by reaction hardening a polyol, a polyisocyanate, and a cross-linking agent, and a cationic structure exists in the molecule structure as a cross-linking agent. Thus, since the stable and uniform existence thereof is accomplished in comparison with the case where quaternary ammonium salt or the like is added as an additive, ink fasts therein more uniformly with the result that images become clear. Also, as required, various additives such as a dispersant, a reaction control agent, and an antifoaming agent can be added, and further an solvent liquid is used as an ink receptor layer to be coated on a base material and thereby manufactured by heating and drying operation. As such, images can be obtained with an excellent glossiness and coloring property and a high drying property combined thereto.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording material used for ink jet printing or copying using a water jet ink or the like using a jet printer.

[0002]

2. Description of the Related Art Ink jet recording is a method in which ink is ejected from nozzles and adheres to a recording medium to perform recording. In recent years, with the spread of electronic still cameras and computers, the technology for recording these images on paper or the like has rapidly developed.In particular, the inkjet method is easy to use in full color and the printing noise is low. In recent years, it is developing rapidly.

[0003] If the ink of the ink jet system is of the solvent type, it dries quickly and the nozzles are easily clogged.
Since the solvent type has a problem in safety to the human body, an aqueous ink is generally used.

[0004] The aqueous ink used in the ink-jet system is an ink using a pigment or a dye or both as a colorant and a water-soluble dispersant.
The target color is expressed by the overlapping of the four black inks.

[0005] As a recording material used in the ink jet system, a material suitable for a place of use (for example, outdoors or indoors), a use method, and the like is selected. For example, a thermoplastic film, a translucent film, paper , Cloth and the like are used.

Usually, a polyhydric alcohol is often added to the aqueous ink in order to prevent nozzle clogging and improve ejection stability. As a recording material for inkjet recording, the ink should be rapidly absorbed (that is,
That the ink dries quickly), that the recording liquid attached later does not flow into the previously attached dots when the ink dots overlap, that the dot shape is close to a perfect circle and that the density is high, The components are required to have excellent color developing properties, excellent ink fixability, high glossiness on the surface, high whiteness, and the like.

Conventionally, most of recording materials used for observing surface images have used a method in which ink is absorbed into porous voids to fix the recording material. JP-A-8-1142
No. 1 discloses a technique of forming an ink absorbing layer using a coating liquid obtained by mixing polyvinyl pyrrolidone, a water-insoluble acrylic resin, and porous silica and organic fine particles with a solvent.

However, these are not glossy on the surface of the recording material due to their porous nature, and it is necessary to provide a non-porous ink-receiving layer in order to obtain glossiness. Had the disadvantage that the drying property was remarkably poor.

Japanese Patent Publication No. 3-42590 discloses an ink receiving layer containing a reaction product of an isocyanate compound and a polyether polyol. Generally, the ether bond itself has a high hydrophilicity and therefore has excellent water-absorbing property, but as in the examples described in this publication, when the porous body is not contained, the ink is dried more than when the porous body is contained. As a result, the drying performance was poor and the drying speed was not sufficient.

[0010]

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, the present invention has excellent ink drying properties and excellent recorded image clarity,
Another object of the present invention is to provide a completely new ink jet recording material having excellent surface gloss.

[0011]

The present invention relates to a polyol,
A recording material for ink-jet recording, comprising a polyurethane elastomer obtained by reacting and curing a polyisocyanate and a cross-linking agent, wherein the polyurethane elastomer has an ionene introduced into a molecular skeleton. Hereinafter, the present invention will be described in detail.

As used herein, "ionene" refers to an ionic segment. The gist of the inkjet recording material of the present invention resides in that a polyurethane elastomer in which ionon is introduced into a molecular structure is used.

The recording material for ink jet of the present invention comprises a polyurethane elastomer. The polyurethane elastomer is obtained by reacting and curing a polyol, a polyisocyanate and a crosslinking agent. The polyol may be a hydrophobic ester component or a hydrophilic ether component, and can be appropriately adjusted depending on the type of ink and the drying property.

In general, dye-type inks exhibit anionic properties. Therefore, the present inventors have noticed that if a cationic structure can be introduced as a cross-linking agent, an anionic ink can be stably fixed, and arrived at the idea that the above object can be achieved by introducing Ionene. Have reached the present invention.

The recording material for ink-jet recording of the present invention has a stable and uniform existence as compared with the case where a quaternary ammonium salt or the like is mixed as an additive because the cationic structure is present in the molecular chain. Since the ink is fixed more uniformly, the image becomes clearer.

This results in an isocyanate content,
The amount of the quaternary ammonium salt in the cross-linking agent can be arbitrarily adjusted, so that not only the fixing property can be easily adjusted according to the type of the ink, but also the physical properties of the ink receiving layer according to the base material can be adjusted. it can.

The fixing property of the anionic ink is related to the cation concentration of the recording material, and when the density is higher than a certain level, the fixing property is remarkably excellent, the image becomes clearer, and the ink absorbing and drying property is also improved. In addition, since the cation concentration can be adjusted depending on the type of the ink, it is possible to cope with any anionic ink.

The present invention is characterized in that Ionene having a repeating unit is introduced into polyurethane. It is preferable that the ionon repeating unit contains a quaternary nitrogen.

The polyurethane according to the present invention can easily be selected for the polyol component forming the soft segment structure, and can be designed in a wide range. It can be freely designed from hydrophobic to hydrophilic.

In the present invention, the ionene segment is introduced to improve the cation concentration in the polyurethane in order to enhance the fixing property of the ink.
Both glossiness and ink absorption drying property can be achieved.
Further, by adjusting the hydrophilicity of the polyol component, even a very thin film can be used.

In the polyurethane elastomer having an ionene structure of the present invention, an isocyanurate crosslink is used as a crosslink structure for the purpose of improving the physical properties as an ink jet recording material, mainly the tackiness after coating and improving the ionene concentration. Therefore, the synthesis is preferably performed in the presence of a solvent.

The ionene-introduced polyurethane of the present invention comprises
First, a polyol and an isocyanate are reacted to form a prepolymer having isocyanate groups at both ends.After having an OH group capable of reacting with an isocyanate at one end, a reaction with an alkyl halide is performed so as to be able to react with the ionene segment. 2-dimethylaminoethanol containing tertiary nitrogen which can be quaternized and exhibiting isocyanurate catalysis can be added and reacted to give a prepolymer of an amine fragment at one end and a terminal isocyanurate.

Next, N, N, N ', N'-tetramethyl-1,6 which forms a solvent and ionomer segment.
-Diaminohexane (TDH) and 1,6-dibromohexane (DBH) are added and reacted while heating and stirring to obtain a polyol elastomer into which ionene has been introduced.

In this manner, since the ionene segment can be introduced later, it has excellent properties as an ink jet recording material for improving the cation concentration in the polyurethane structure as described above. A polyurethane elastomer can be obtained.

The repeating unit of Ionene is not particularly limited, and examples thereof include those represented by the following formula.

[0026]

Embedded image

If necessary, various additives such as a dispersant, a reaction regulator and an antifoaming agent can be added to the polyurethane elastomer. The solvent solution thus manufactured is used as an ink receiving layer. The ink receiving layer can be manufactured by coating a base material by various methods and then drying by heating. The thickness of the ink-receiving layer on the substrate can be usually adjusted by applying a coating liquid on the substrate such that the thickness after drying is about 1 to 200 μm. The thickness of the ink receiving layer after drying is more preferably 10 to 50 μm.

[0028]

The present invention will be described below in detail with reference to examples of the present invention, but the present invention is not limited to these examples. Example 1 Polytetramethylene glycol having a molecular weight of 1000 (PTMG-1000, manufactured by Sanyo Chemical Industries, Ltd.) as a synthetic polyol of an isocyanate-terminated prepolymer
And polyoxyethylene glycol having a molecular weight of 1000 (manufactured by Sanyo Chemical Industries, Ltd., PEG1000) were blended at a molar ratio of 7: 3. Next, 4,4′-diphenylmethane diisocyanate (MDI, manufactured by Nippon Polyurethane Industry Co., Ltd., Millionate MT) was added so that the molar ratio of NCO / OH became 2/1, and the mixture was stirred at 65 ° C. under a nitrogen atmosphere. An isocyanate-terminated prepolymer was obtained. The end of the reaction
It was confirmed by the residual NCO group concentration by the amine equivalent method.

Synthesis of amine-terminated prepolymer To the isocyanate-terminated prepolymer, dimethylformamide (DMF) was added in an amount of 20 m per 0.01 mol of polyol.
L was added and the mixture was heated and stirred for about 90 minutes to obtain an amino-terminated prepolymer. The end of the reaction was confirmed by the disappearance of the absorption at 2275 cm ⁻¹ , which is the absorption of NCO, by FT-IR.

Synthesis of Polyurethane Ionene DMF was further added to the prepolymer obtained above to form a solution, and -N (CH) was added so that the N ⁺ concentration was 2% by weight.
₃ ) _{2 /} TDH / DBH = 1/1 / 1.5 molar ratio and reacted for about 3.5 hours to obtain a polyurethane ionene for a recording material for inkjet. This was applied to a general copy paper by a bar coater method so that the coating film became 20 μm, and dried at 100 ° C. for 3 hours to obtain an inkjet recording material.

Example 2 In the synthesis of polyurethane ionene, -N (CH ₃ ) ₂ / TDH was adjusted so that the N ⁺ concentration was 1.5% by weight.
An ink-jet recording material was obtained in the same manner as in Example 1, except that / DBH was added at a molar ratio of 2/1/2.

Example 3 In synthesizing an isocyanate-terminated prepolymer, a polyol was used as a polyethylene adipate having a molecular weight of 1,000 (Nipporan 400 manufactured by Nippon Polyurethane Industry Co., Ltd.).
A recording material for ink jet was obtained in the same manner as in Example 1 except that step 2) was performed.

Comparative Example 1 The prepolymer was synthesized in the same manner as in Example 1. Thereafter, the prepolymer was dissolved in DMF, and the weight ratio of 1,4-butanediol to trimethylolpropane was 60/40.
Was added in such a manner that the NCO / OH molar ratio was 1.0, and in the same manner as described above, an ink-jet recording material (a material comprising a polyurethane not having an ionene structure) was obtained. Comparative Example 2 An ink-jet recording material (comprising a polyurethane not having an ionene structure) was obtained in the same manner as in Comparative Example 1 except that the polyol was the polyethylene adipate used in Example 3.

Examples 1 to 3 prepared as described above,
With respect to the ink jet recording materials of Comparative Examples 1 and 2, the glossiness was evaluated before printing, and after printing using a commercially available A4 size ink jet printer, the ink drying property and the coloring property were evaluated as follows. Performed by the method. The results are shown in Table 1.

Evaluation method 1) Glossiness: According to JIS K 7105, the reflectance at 60 degrees of incident light and reflected light was determined using a gloss meter VGS-1D manufactured by Nippon Denshoku Industries Co., Ltd. 2) Ink drying property: After printing, the ink was left at 24 ° C. and 50% RH, and the time required for ink to be removed by touching with a hand was measured. 3) Color development: After printing, visual observation was made, and those with sufficient color development were evaluated as ○, and those with insufficient color development were evaluated as x.

[0036]

[Table 1]

[0037]

According to the present invention, a recording material for ink-jet recording which has the above-mentioned structure, provides a clear image excellent in glossiness and coloring, and also has high drying properties (absorptivity). Can be provided.

Continued on the front page (72) Noriko Hiraoka, Inventor 1-4-52-1107, Nagasaki-shi (72) Takako Terada, Inventor 17-18, Hashiguchicho, Nagasaki-shi

Claims (4)

[Claims] 1. A recording material for ink-jet recording, comprising a polyurethane elastomer obtained by reacting and curing a polyol, a polyisocyanate and a cross-linking agent, wherein the polyurethane elastomer has an ionene introduced into a molecular skeleton. 2. The recording material for ink-jet recording according to claim 1, wherein the repeating unit of Ionene contains quaternary nitrogen. 3. The ink-jet recording material according to claim 1, wherein the ionene is introduced by incorporating an ionene segment after synthesizing a polyurethane comprising a polyol and an isocyanate. 4. The ink-jet recording material according to claim 1, wherein the chemical structure of the repeating unit of Ionene is represented by the following formula. Embedded image