JP2002264469A - Ink jet recording sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording sheet suitable for use in a state in which an ink acceptive layer is stretched or the like by the layer is stretched by suppressing a crack of the layer, a decrease in an image density when the layer is stretched. SOLUTION: The ink jet recording sheet comprises the ink acceptive layer containing a filler on a base. The ink acceptive layer has an elongation measured when a thickness is 0.1 to 0.2 mm based on JIS K 6301 of 1,000 to 2,000%, and contains a binder having a 100%-modulus of 0.1 to 1.0 MPa. A decrease in an image density of a black ink when the sheet is stretched by 55% is 15% or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording sheet, and more particularly, to a sheet for use in a stretched state in which cracking of an ink receiving layer and reduction in image density when stretched are suppressed. It relates to a suitable ink jet recording sheet.

[0002]

2. Description of the Related Art As one of the printing methods, the ink jet recording method has been widely used due to the advantages that a high-quality full-color image can be easily obtained and the running cost is low. Among the uses of a recording sheet printed by such an ink jet recording method, the sheet may be elongated when used.

A typical example is that, first, an ink jet recording sheet is manufactured using a stretchable base material, an adhesive is applied thereto, and after printing, the sheet rises along the surface of the article. This is the case where the sticking is performed without any wrinkles or the like. For example, when an article to which an ink jet recording sheet is to be attached (hereinafter, referred to as an “adherend”) has a curved surface or irregularities instead of a flat surface, the object is adhered so as not to cause a floating portion or wrinkles. In order to adhere along the surface shape of the body, it is necessary to partially stretch the ink jet recording sheet. In such a case, the stretchable base material is used as described above, and a part of the inkjet recording sheet is stretched after the application.

Second, when the adherend has elasticity, for example, in the case of an article such as rubber, if the ink jet recording sheet does not expand and contract in accordance with the elasticity of the adherend, peeling from the adherend occurs. Also in such a case, a stretchable base material is used, and when the adherend expands and contracts after sticking, the ink jet recording sheet also expands and contracts.

[0005] Third, when the ink jet recording sheet is stretched when used, post-processing such as molding or embossing is performed, and the ink jet recording sheet is deformed, and a part or all of the sheet is deformed. May be used in an extended state.

In the above case, conventionally, a material having elasticity or a material suitable for post-processing has been selected and used as the base material. However, the printing performance of the base material alone is poor. A receiving layer is provided. However, the ink receiving layer may crack when it expands and contracts. When cracks occur, the ink receiving layer is likely to peel off from the substrate in the form of fine fragments, and such cracks and peelings are easily visible to the naked eye even in unprinted white paper, and there is a problem that the appearance is impaired. .

When the ink jet recording sheet is stretched, the printed portion is also stretched, but the image density of the portion is reduced, resulting in a poor impression of the image or unevenness of the image. There was also the problem of doing. In particular, the phenomenon was conspicuous in a black print portion. This decrease in image density may occur because the amount of ink per unit area is relatively reduced simply because the ink is stretched, and when carefully observed, a large number of fine cracks are generated in the printing portion, and In some cases, a decrease in image density is promoted. It should be noted that the fine cracks are of such a degree that it is difficult to find them with the naked eye in the state of blank paper.

[0008] To solve the problem of cracking of the ink receiving layer, various techniques have been proposed such as softening the ink receiving layer by containing a plasticizer, but the effect has not always been obtained sufficiently. is the current situation. At the present time, there has been no ink jet recording sheet which has solved the problem of image density reduction in applications where the sheet is stretched.

[0009]

SUMMARY OF THE INVENTION In view of the above situation, the present invention suppresses cracking of the ink receiving layer and reduction in image density when the ink jet recording sheet is stretched and the like. It is an object of the present invention to provide an ink jet recording sheet which is excellent in image quality in a state where the image is formed.

[0010]

Means for Solving the Problems An object of the present invention, which has been made to solve the above problems, is to provide an ink jet recording sheet having a base material provided with an ink receiving layer containing a filler, wherein the ink receiving layer is , The elongation when measured with a thickness of 0.1 to 0.2 mm based on JIS K6301 is 1000 to
It contains a binder having 2000% and a 100% modulus of 0.1 to 1.0 MPa, and a decrease in image density of black ink when the sheet is stretched by 55% is 15% or less. .

The inventor of the present invention has to provide the ink receiving layer with a certain degree of elasticity so that the ink receiving layer is not easily broken when the ink jet recording sheet is stretched or the like. What is necessary is that the ink receiving layer has an elongation of 1000 to 2000% when measured at a thickness of 0.1 to 0.2 mm based on JIS K6301 and 100 to 100%.
It was found that a binder having a% modulus of 0.1 to 1.0 MPa should be contained, and the present invention was completed.
By including this binder, fine cracks are also suppressed, and the fine cracks are suppressed, and by appropriately using a filler, a decrease in image density when the ink receiving layer is elongated is suppressed. I also found it to be. Further, when the inkjet recording sheet is stretched, specifically, when the image density of the black ink is reduced by 15% or less when the sheet is stretched by 55%, it is stretched when actually used. It has been found that the image in the portion where the image has disappeared is almost inferior and can be suitably used.

The constitution of the present invention is as described above, but the content of the binder in the ink receiving layer can be 20 to 60% by weight based on the total solid content of the ink receiving layer. In addition, a stretchable material can be used for the base material, and the stretchable base material preferably has an elongation according to JISK6732 of 50 to 300% in the vertical and horizontal directions. . In the present invention, a decrease in image density can be adjusted by adjusting the average particle diameter of the filler and the thickness of the ink receiving layer, or the mode diameter of the filler and the thickness of the ink receiving layer. Further, in the present invention, a pressure-sensitive adhesive sheet can be manufactured by providing a pressure-sensitive adhesive layer on the side of the substrate on which the ink-receiving layer is not provided, and providing release paper on the pressure-sensitive adhesive layer.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the ink jet recording sheet of the present invention will be described. The recording sheet of the present invention has a layer structure in which an ink receiving layer is provided on a base material as described below, and an anchor coat layer or an intermediate layer may be appropriately provided between the base material and the ink receiving layer. it can.

The substrate in the recording sheet of the present invention is not particularly limited, and any substrate may be used as long as it has elasticity or can be elongated by post-processing. For example, a plastic film, rubber, stretchable cloth or paper, or the like can be used. When using a material having elasticity, the elongation according to JIS K6732 is preferably in the range of 50 to 300% in the vertical and horizontal directions. If it is less than 50%, the elongation when used is small, and the significance of using the present invention becomes poor. If the ratio exceeds 300%, the ink receiving layer is excessively stretched by applying a slight force, so that even if the present invention is used, the ink receiving layer often cracks. More preferably, it is 180 to 250%. As a material,
A vinyl chloride resin is particularly preferably used in terms of stretchability, workability, and the like.

There are various types which are elongated by post-processing or the like. For example, a certain kind of plastic film can be formed by using a vacuum forming method after being softened by heating. Examples of such a plastic film include a vinyl chloride film and a non-stretched polystyrene film. In addition, many plastic films can be embossed. Embossing generally transfers the unevenness of a plate to a sheet by applying heat or pressure. Use of the present invention is significant in the case of a pattern having a large difference in unevenness or when embossing is performed after printing. In particular, a foamed plastic film is preferably used from the viewpoint of reproducibility and concealment of the embossed pattern. Here, the foamed plastic film refers to a plastic film having cracks or voids formed on the surface or inside of the film, or having fine bubbles or cavities, and these bubbles or cavities are made of inorganic material such as calcium carbonate. Name and method of forming, such as stretching a powder-containing film to create cavities around the inorganic powder (microvoid film) or foaming a foaming agent in a film containing a foaming agent Alternatively, the form of generation of bubbles or cavities is not limited.

Although the typical examples have been described above, the base material of the present invention is not limited to these, and may be any material that elongates at any stage of processing or use, regardless of the purpose or method. Can be used. In addition, from the viewpoint of the material,
Examples include a general thermoplastic resin film such as vinyl chloride, polyethylene terephthalate, polypropylene, polystyrene, and polycarbonate, a film in which an inorganic powder such as calcium carbonate is internally added, and a film in which an organic pigment is internally added. Further, from the aspect of the structure, a multilayered structure, a foamed plastic film, and the like are included.
Moreover, what is called synthetic paper is also included.

Next, JIS K6 is used for the ink receiving layer of the present invention.
Based on 301, the elongation measured at a thickness of 0.1-0.2 mm is 1000-2000% and the 100% modulus is 0.1
A binder of ~ 1.0 MPa is included. This allows
When the ink jet recording sheet is stretched or the like, cracks and minute cracks in the ink receiving layer hardly occur.
For elongation and 100% modulus, see JIS K6301
Describes a plurality of measurement methods. In the present invention, the thickness of the coating film is 0.1 to 0.2 mm, and the shape of the test piece is defined as a dumbbell-shaped No. 2 type, and is defined by a value measured.

The content of the binder is preferably in the range of 20 to 60% by weight based on the total solid content of the ink receiving layer. If the amount is less than 20% by weight, cracks and fine cracks in the ink receiving layer tend to occur. If the amount is more than 60% by weight, there is less room for the filler to be contained, so that the ink absorbency is insufficient. More preferably, it is 35 to 45% by weight. As the kind of the substance, various known substances can be used. Examples thereof include polyurethane, but the material is not limited thereto, and a type satisfying the above-mentioned elongation and 100% modulus can be selected and used. In particular, from the viewpoint of light resistance, a non-yellowing type ester-based polyurethane resin can be suitably used. Further, from the viewpoint of ink fixability, cationic ones are preferable.

The ink receiving layer contains a filler. By the way, the inventor of the present invention has found that the smaller the ratio of the particle diameter of the filler to the thickness of the ink receiving layer, the smaller the decrease in image density when the ink receiving layer is elongated. This phenomenon is presumed to be related to the size of the pigment mass in the ink, which exists in large numbers on the surface and inside of the ink receiving layer of the printing section. When the ink receiving layer is stretched and the gaps of the dye mass increase on the surface, in other words, on the portion that is visible, the image density is considered to decrease. The pigment mass is distributed three-dimensionally, and it is not only the pigment mass present on the outermost surface from the beginning that is visible during the elongation process. Therefore, it is a complicated phenomenon, but it is presumed that the gap is less likely to increase when the ink receiving layer is formed of a mass of the dye smaller than the thickness of the ink receiving layer. When the particle diameter of the filler is small, the voids between the fillers and the pores of the filler tend to be small, and it is presumed that the mass of the dye becomes small.

In the present invention, the ratio of the particle diameter of the filler to the thickness of the ink receiving layer and the above-mentioned binder are used to elongate the ink jet recording sheet, specifically 55% elongation. The ink receiving layer is adjusted so that the decrease in the image density of the black ink is 15% or less. When this level is reached, the impression of the image does not deteriorate so much even when it is expanded, and it is possible to reach this level by using the present invention. The method of adjusting the ink receiving layer in such a manner is as described below. That is, first, as described above, based on JIS K6301, the elongation when measured with a thickness of 0.1 to 0.2 mm is 1000 to 2000
% And a 100% modulus of 0.1 to 1.0 MPa are contained in the ink receiving layer to reduce fine cracks and suppress a decrease in image density. Then, adjustment is made to reach the above-mentioned level by using adjustment means related to the ratio of the particle diameter of the filler to the thickness of the ink receiving layer. As the adjusting means, there are the following two methods.

The first is a method of adjusting the filler by focusing on the average particle diameter and content of the filler by the Coulter counter method. For example, when the following conditions are simultaneously satisfied, the reduction in the image density of the black ink when the inkjet recording sheet is elongated by 55% is usually 15% or less. That is, (1) the thickness of the ink receiving layer is 25 to 35 μm. (2) The ink receiving layer contains 25 to 35% by weight of a filler having an average particle size of 2 to 6 μm based on the Coulter counter method, based on the total solid content of the ink receiving layer. (3) The ink receiving layer contains a filler having an average particle diameter of 10 to 15 μm by a Coulter counter method in an amount of 0 to 15% by weight based on the total solid content of the ink receiving layer. It is a condition.

The second method focuses on the mode diameter of the filler and the thickness of the ink receiving layer measured by a laser method. Paying attention to the mode diameter of the filler in the coating liquid for forming the ink receiving layer measured by the laser method, this value is set to r. Assuming that the thickness of the ink receiving layer is t, 0.
If the relational expression of 1t ≦ r ≦ 0.3t is satisfied, the decrease in the image density of the black ink when expanded by 55% tends to be 15% or less.

The filler used in the present invention can be selected from various known fillers. For example, silica, calcium carbonate, magnesium carbonate, diatomaceous earth, talc, titanium oxide, alumina sol and the like can be mentioned, and these can be used alone or in combination. In particular, synthetic silica is preferable from the viewpoint of ink absorption capacity, and particularly, oil absorption is 200 to 230 m.
1/100 g is preferred.

Here, in the case where an ink receiving layer having a thickness of about 30 μm, which is relatively practical, is provided in an ink jet recording sheet, selection of a filler to be contained in the receiving layer will be described. When an ink receiving layer having a thickness of about 30 μm is provided, it is preferable that the ink receiving layer contains a filler having an average particle diameter of 2 to 6 μm by a Coulter counter method. If it is less than 2 μm, the ink receiving layer is likely to crack. If it exceeds 6 μm, the effect of suppressing a decrease in image density not caused by minute cracks when the ink receiving layer is elongated becomes insufficient. More preferably, it is 3.0 to 4.0 μm. The content of the filler having an average particle diameter of 2 to 6 μm by the Coulter counter method is preferably 20 to 70% by weight based on the total solid content of the ink receiving layer. If the amount is less than 20% by weight, the effect of suppressing a decrease in image density when the ink receiving layer is elongated is insufficient, and if it exceeds 70% by weight, the abrasion resistance of the ink receiving layer is reduced. More preferably, it is 30 to 50%.

Further, when the ink receiving layer having a thickness of about 30 μm is provided, when the receiving layer contains a filler having an average particle diameter of 2 to 6 μm according to the Coulter counter method, it is not necessary to use only the filler. Mixing and using a filler having a larger average particle diameter than this is also one of the preferable embodiments. A filler with a small average particle diameter suppresses a decrease in image density when the ink receiving layer is elongated, but a filler with a large average particle diameter is more effective in terms of the strength of the ink receiving layer and the difficulty of cracking when elongated. It is. The average particle diameter of the filler having a large average particle diameter according to the Coulter counter method is preferably in the range of 10 to 15 μm. Further, the ratio of the content of the filler having an average particle size of 2 to 6 μm and the content of the filler having a particle size of 10 to 15 μm by the Coulter counter method is preferably in the range of 100: 0 to 50:50 by weight. Regarding the filler having a large average particle size, synthetic silica is particularly preferable from the viewpoint of ink absorption ability, and among them, those having an oil absorption of 200 to 230 ml / 100 g are preferable. When the filler having a large average particle diameter is mixed in this way, the ink absorbency is appropriately improved.

The ink receiving layer may contain other substances according to various purposes in addition to the binder and the filler. For example, cationic substances such as quaternary ammonium salts, dicyandiamide-based, polyamine-based, and alkylamine-based substances may be used for the purpose of improving the fixing property of the ink. Further, various additives such as a surfactant, an antistatic agent, and an ultraviolet absorber can be contained.

The ink receiving layer can be formed by various known methods such as coating, spraying, and dipping. In particular, reverse roll coat, air knife coat, gravure coat,
Coating by blade coating or the like is desirable. After coating,
It is desirable to dry using a method such as airless drying and an oven. Further, an anchor layer may be provided between the substrate and the ink receiving layer for the purpose of improving the adhesion. Furthermore, the ink jet recording sheet of the present invention may have a configuration in which a pressure-sensitive adhesive layer is provided on the side of the substrate on which the ink-receiving layer is not provided, and release paper is provided thereon, and can be used as a pressure-sensitive adhesive sheet.

[0028]

The present invention is as described above. According to the ink jet recording sheet of the present invention, since the ink receiving layer is provided with elasticity, the ink jet recording sheet can be used in the manufacturing process. Even in the case of elongation or the like, cracking or peeling from the base material does not substantially occur in the ink receiving layer, and a decrease in image density can be effectively suppressed. Further, since the decrease in the image density of the black ink when expanded by 55% is suppressed to 15% or less, there is no inferior quality even when expanded when used.

Therefore, the ink jet recording sheet of the present invention is used by attaching it to the surface of an adherend having a curved surface or an uneven surface, and the adherend has elasticity such as rubber. It is very suitable for applications such as molding, and applications such as post-processing such as molding.

[0030]

Next, an embodiment of the present invention will be described. Note that the present invention is not limited by these examples.

Example 1 Adhesive vinyl chloride film (Fc1312 / PSA (38), manufactured by Riken Vinyl Industry Co., Ltd.) as a substrate
The elongation conforming to JIS K-6732 is 182% or more in height and 190% in width.
The above was used. In this case, an adhesive was applied to a vinyl chloride film having a thickness of 80 μm, and release paper was provided. After applying a coating liquid of an anchor layer having the following composition on this substrate, a coating liquid of an ink receiving layer having a composition shown in Table 1 below was applied so that the thickness of the receiving layer was 30 μm. Thus, an ink jet recording sheet as an example of the present invention was obtained. [Composition of anchor layer] Acrylic resin 30 parts by weight Calcium carbonate 10 parts by weight Water 60 parts by weight

[0032]

[Table 1]

(Comparative Example 1) In Example 1, the filler in the coating solution for the ink receiving layer was Thysia 440.
Was 11.0 g and Mizukasil P78F was 5.0 g, and the total amount was 16.0 g.
Without using 0, Mizukasil P78F alone weighed 16.0 g. Otherwise, in the same manner as in Example 1, an ink jet recording sheet was obtained.

(Comparative Example 2) Using the same substrate as in Example 1, a coating liquid for the anchor layer having the above composition was applied on the substrate, and then an ink having the composition shown in Table 2 below was applied. The coating liquid for the receiving layer was applied so that the thickness of the receiving layer was 30 μm, to obtain a sheet for inkjet recording.

[0035]

[Table 2]

(Comparative Example 3) The same base material as in Example 1 was used, and a coating solution for the anchor layer having the above composition was applied on this base material. The coating liquid for the receiving layer was applied so that the thickness of the receiving layer was 30 μm, to obtain a sheet for inkjet recording.

[0037]

[Table 3]

(Comparative Example 4) A binder in the ink receiving layer was made of Adecabon Titer HUX-240 (available from Asahi Denka Kogyo KK
An ink jet recording sheet was obtained in the same manner as in Comparative Example 3, except that 70%, 100% modulus could not be measured, and an ester-based polyurethane resin was used.

(Comparative Example 5) The same base material as in Example 1 was used, and a coating solution for the anchor layer having the above composition was applied on the base material. The coating liquid for the receiving layer was applied so that the thickness of the receiving layer was 30 μm, to obtain a sheet for inkjet recording.

[0040]

[Table 4]

As described above, the ink-jet recording sheets obtained in Example 1 and Comparative Examples 1 to 5 were evaluated for “evaluation items” shown in Table 5 below.

[0042]

[Table 5]

Table 6 shows the evaluation results.

[0044]

[Table 6]

Claims (5)

[Claims] An ink-jet recording sheet comprising a substrate and an ink-receiving layer containing a filler provided on a substrate, wherein the ink-receiving layer has an elongation of 1,000 to 2,000 when measured at a thickness of 0.1 to 0.2 mm according to JIS K6301. % And 100%
Contains a binder having a modulus of 0.1 to 1.0 MPa,
A sheet for ink jet recording, wherein a decrease in image density of black ink when the sheet is elongated by 55% is 15% or less. 2. The ink jet recording sheet according to claim 1, wherein the binder is contained in an amount of 20 to 60% by weight based on the total solid content of the ink receiving layer. 3. The method according to claim 1, wherein the reduction in image density is reduced to 15% or less by adjusting the average particle diameter of the filler and the thickness of the ink receiving layer as described in the following (1) to (3). 2
Sheet for inkjet recording. (1) The thickness of the ink receiving layer is 25 to 35 μm. (2) The ink receiving layer contains a filler having an average particle diameter of 2 to 6 μm according to the Coulter counter method in a total solid content of the ink receiving layer of 25 to 35% by weight. (3) The ink receiving layer contains 0 to 15% by weight of a filler having an average particle diameter of 10 to 15 μm based on the Coulter counter method, based on the total solid content of the ink receiving layer. 4. The ink jet recording sheet according to claim 1, wherein a mode diameter r of the filler and a thickness t of the ink receiving layer measured by a laser method satisfy the following relational expression. 0.1t ≦ r ≦ 0.3t 5. The pressure-sensitive adhesive layer is provided on the side of the substrate on which the ink receiving layer is not provided, and a release paper is provided on the pressure-sensitive adhesive layer.
5. The sheet for inkjet recording according to any one of items 1 to 4,