JPH09175009A - Primer agent for polyester film and ink jet recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a primer agent capable of forming an easily adhesive coat for strongly sticking a polyester film to an ink receptive layer without deteriorating the ink absorptive properties of the ink receptive layer. SOLUTION: This primer agent for polyester film consists of at least, polyisocyanate and a polyester resin which has a hydroxyl group value of 1-30. In addition, the polyisocyanate and the polyester resin are mixed in such a manner that the NCO group of the polyisocyanate and the hydroxyl group of the polyester resin are set to the range of a mole ratio (1:1)-(10:1).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester film primer agent, and further relates to a polyester film primer agent and an inkjet recording material capable of forming an easily adhesive coating film having excellent adhesion to a polyvinyl alcohol resin. .

[0002]

2. Description of the Related Art A thermoplastic polyester such as polyethylene terephthalate or a polymer thereof, polyethylene naphthalate or a polymer thereof, or a blend thereof with a small proportion of another resin is melt-extruded and biaxially stretched, followed by heat setting. The polyester film thus obtained has a problem that it is poor in acceptability of paints, adhesives, inks, etc. because the surface thereof is highly crystallographically oriented. Therefore, there are drawbacks that the recording ink is not absorbed, the ink flows and the image becomes unclear, and the recording image is soiled or stuck due to rubbing or superposition due to poor drying of the ink.

In order to provide the polyester film with appropriate ink absorbency in order to solve such inconvenience, a water-soluble polymer such as polyvinyl alcohol or polyvinylpyrrolidone is coated on the polyester film to form an ink receiving layer (special feature: KAISHO 61-10483 gazette, 61-
No. 188181) has been proposed.

However, such a water-soluble polymer has poor adhesiveness to the polyester film as the base material, and when the ink reaches the surface of the base material after recording, the interfacial adhesive force between the base material and the ink receiving layer is weakened. Therefore, there is a problem that the ink receiving layer is lifted or peeled off.
Among the water-soluble polymers, polyvinyl alcohol is particularly excellent in various properties such as ink absorbency, drying property, and transparency as compared with other water-soluble polymers such as polyvinylpyrrolidone. It has been desired to develop a primer agent that is suitable as a main resin and that firmly adheres polyvinyl alcohol and a polyester film.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and firmly adheres both the polyester film and the ink receiving layer without lowering the ink absorbability of the ink receiving layer. It is an object of the present invention to provide a primer agent capable of forming an easily-adhesive coating film and an ink jet recording material using the same.

[0006]

This object is solved by the present invention described below. That is, the present invention is a polyester film primer agent comprising at least polyisocyanate and a resin having good compatibility with polyisocyanate, wherein the resin having good compatibility with polyisocyanate has a hydroxyl value of 1 to 30, and The polyisocyanate and the resin having good compatibility with the polyisocyanate are mixed such that the NCO group of the isocyanate and the hydroxyl group of the resin having good compatibility with the polyisocyanate are in a molar ratio of 1: 1 to 10: 1. It is characterized by being done. Particularly, the resin having good compatibility is preferably a polyester resin from the viewpoint of adhesiveness to both the polyester film and the ink receiving layer which are base materials.

In the ink jet recording material of the present invention, a primer agent having the above composition is applied to at least one surface of a polyester film, and the NCO in the primer agent is applied.
While the group remains, it is characterized in that it is formed by laminating an ink-receiving layer made of a hydrophilic or water-soluble resin containing a hydroxyl group, in particular, the hydrophilic or water-soluble resin containing a hydroxyl group is polyvinyl alcohol. In some cases, the adhesiveness is outstandingly improved, which is preferable.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

The polyester film primer agent of the present invention comprises at least a polyisocyanate, a resin having a high compatibility with the polyisocyanate, and a solvent.

Here, since polyisocyanate crosslinks with a resin having a high compatibility with the polyisocyanate described later and also crosslinks with the hydroxyl group of polyvinyl alcohol, it is necessary to have appropriate reactivity and NCO group.

The chemical bond that can occur in the present invention must occur not only between the resin and the isocyanate described later in the primer agent, but also between the hydroxyl groups of the resin constituting the ink receiving layer described below.

Therefore, when a highly reactive polyol is used as the constituent material of the primer agent, if the amount of isocyanate added to the primer agent is less than a certain amount, only the chemical bond in the primer agent will proceed, and it will form a bond with the ink receiving layer. Since the adhesive strength is not improved, it is necessary to select the amount of the polyisocyanate so that the chemical bond in the primer agent is appropriately caused and the hydroxyl group of the resin constituting the ink receiving layer can be reacted.

The resin having a good compatibility with the polyisocyanate is preferably in the range of 1 to 30 although the hydroxyl value is in the range of 1 to 30, though it depends on the reactivity with the polyisocyanate or the resin constituting the ink receiving layer. This is because if it is too small, the chemical bond with the polyisocyanate becomes weak, and if it exceeds 30, the chemical bond with the resin forming the ink receiving layer described later does not occur easily.

Specific examples thereof include polyester resin, polyvinyl butyral, polyvinyl acetal, acrylic resin and the like. Among them, the polyester resin is most suitable from the viewpoint of adhesiveness to the polyester film.

The amount of polyisocyanate cannot be generally determined depending on the kind of resin having good compatibility with polyisocyanate having a hydroxyl group, but the molar ratio of NCO group and hydroxyl group is 1: 1.
Amounts in the range of -10: 1 are suitable. The reason for this limitation is that if the amount of NCO groups is smaller than this, the chemical bond of the primer agent itself greatly increases and the adhesiveness to the ink receiving layer deteriorates, while if it is too large, the NCO groups are added more than necessary. This is because it reacts with the hydroxyl groups of the layer and self-crosslinking proceeds to form a hard and brittle film, which reduces the adhesive strength.

In order to cause the chemical bond between the ink receiving layer and the primer layer to occur only at the interface between them, the molar ratio must be within the above range. This is because the progress of self-crosslinking of the ink receiving layer itself causes the above-mentioned inconvenience and impairs various recording characteristics of the ink receiving layer.

Basically, any solvent may be selected as the primer agent, but a solvent having a hydroxyl group such as water or alcohol, or a polar solvent in which water is easily mixed cannot react with the polyisocyanate. In this case, the polyisocyanate may be in the form of blocked isocyanate.

Further, the primer agent contains a coloring agent, an ultraviolet absorber, a leveling agent, to the extent that the above performance is not impaired.
It may be one to which an additive such as a surfactant is added.

The primer agent of the present invention having such a constitution is coated on a polyester film by a known coating method such as a roll coating method, a bar coating method, a spray coating method and an air knife coating method, and then dried. Can be formed by. The coating thickness at that time is preferably 0.1 to 5 μm. If it is thinner than this, good adhesion to the substrate and the ink receiving layer described later cannot be obtained. On the other hand, if it is thicker than this, there is no big problem, but the film thickness ratio with the ink receiving layer becomes large, and the cost is low. This is because it causes problems in terms of strain on the surface and the material itself.

Further, after the primer layer is formed, before the NCO group of the polyisocyanate and the hydroxyl group of the resin are chemically bonded, an ink receiving layer described later is formed by the same method as that for the primer agent.

The ink receiving layer is a water-soluble or hydrophilic resin having a swelling property for an aqueous ink, for example, albumin, gelatin, casein, starch, gum arabic, natural resin such as sodium alginate, carboxymethyl cellulose, hydroxyethyl cellulose, Polyamide, polyacrylamide, polyhydroxyethylmethacrylate, polyphenylacetoacetal, polyethyleneimine, polyvinylpyrrolidone, polyvinylpyridinium halide, melamine resin, polyurethane, polyvinyl alcohol, polyester, polyacrylic acid soda, acrylic acid ester copolymer, etc. 1 One kind or a mixture of two or more kinds can be used.

However, in relation to the primer agent in the present invention, the adhesiveness is extremely improved in the case of a polyvinyl alcohol-based resin having extremely poor adhesiveness to the polyester film. Therefore, for these reasons, it can be said that the polyvinyl alcohol resin which is excellent in various recording characteristics is a preferable resin.

As described above, after the ink jet recording material is manufactured, even if it is stored at room temperature, the above-mentioned reaction proceeds and a good adhesive strength is gradually obtained, but curing is performed at a temperature of about 40 to 80 ° C. It is preferable to use the adhesive because stable adhesiveness can be obtained in a short time.

[0024]

An embodiment of the present invention will be described. In addition, unless otherwise indicated, parts and% are based on weight.

[Example] A coating liquid for a primer agent having the following composition was coated on a polyester film by bar coating so that a dry film thickness was 1.0 µm, and further, a coating liquid for an ink receiving layer having the following composition. Was similarly applied and dried to form an ink receiving layer having a thickness of 10 μm.

The isocyanate prepolymer NC
The molar ratio of O groups to OH groups of the polyester resin is 1.7:
It was 1.0.

<Coating liquid for primer layer> -Polyester resin (OH value 3) 2.0 parts (ELITEL UE3201 solid content 100%: Unitika) -Isocyanate prepolymer (solid content 60%) 0.5 part (takenate) D110N: Takeda Pharmaceutical Company Limited) -Methyl ethyl ketone 10.5 parts-Toluol 10.0 parts

<Ink-Receptive Layer Coating Liquid> -Polyvinyl alcohol 1.0 part (Gothenol KH17: Nippon Synthetic Chemical Industry Co., Ltd.)-Water 9.0 parts

[Comparative Example 1] On a polyester film,
The ink receiving layer coating liquid of Example 1 was directly applied to form an ink receiving layer.

[Comparative Example 2] On a polyester film,
After coating and forming the same primer layer coating liquid as in Example 1, heat treatment was performed at 60 ° C. for 24 hours to completely react the NCO groups, and then the same ink receiving layer coating liquid as in Example 1 Was applied to form an ink receiving layer.

The ink jet recording materials obtained in Examples and Comparative Examples were left for one week at room temperature and cured at 60 ° C. for 24 hours, and the adhesiveness and printability were evaluated. The results are shown in Table 1.

Regarding the adhesiveness, a cross-cut adhesion test was conducted, and the completely adhered one was set to 100%.

Regarding printability, BJ600J
(Canon Co., Ltd.) is used to perform solid printing in color. “O” indicates that the ink does not bleed and dries, “△” indicates that the ink is poorly dried and the bleeding is severe, and “x” indicates that the ink does not dry.
And

[0034]

[Table 1]

The products obtained in the Examples have good adhesiveness and printability under both conditions, whereas Comparative Example 1 has no primer layer and therefore has no adhesiveness. Since all the NCO groups in the isocyanate were chemically bonded in the primer layer, there was no portion that reacted with the ink receiving layer, and the adhesiveness was 0%.

[0036]

INDUSTRIAL APPLICABILITY As described above, the primer agent for a polyester film of the present invention can not only adhere to the polyester film, but also can strongly adhere to the ink receiving layer and yet deteriorate the recording characteristics of the ink receiving layer. It has an excellent effect that it does not exist.

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Claims (4)

[Claims] 1. A primer agent for a polyester film comprising at least polyisocyanate and a resin having good compatibility with polyisocyanate, wherein the resin having good compatibility with polyisocyanate has a hydroxyl value of 1 to 30,
And the polyisocyanate and the resin having good compatibility with the polyisocyanate so that the NCO group of the polyisocyanate and the hydroxyl group of the resin having good compatibility with the polyisocyanate are in a molar ratio of 1: 1 to 10: 1. A primer agent for a polyester film, which is a mixture of and. 2. The primer agent for a polyester film according to claim 1, wherein the resin having good compatibility is a polyester resin. 3. An ink-receiving layer comprising a hydrophilic or water-soluble resin containing a hydroxyl group on the polyester film while the NCO group in the primer agent remains on the polyester film. An ink jet recording material comprising: 4. The ink jet recording material according to claim 3, wherein the hydrophilic or water-soluble resin containing a hydroxyl group is polyvinyl alcohol.