JPS5995188A - Ink jet recording paper - Google Patents

Abstract

PURPOSE:To provide an ink jet recording paper suitable for ink jet recording using an oil base ink, capable of recording in high density and having excellent water resistance, by using as a binder a resin which is insoluble in water but soluble in organic solvents. CONSTITUTION:A binder resin soluble in a solvent of an oil base ink for ink jet recording is incorporated in a coated layer on the recording paper. Namely, an aqueous emulsion type high polymer is used as a binder resin incorporated in the coated layer. An example of the high polymer is polyvinyl acetate. Accordingly, since an oil base ink and a water-resistant binder are used, a recorded matter has excellent water resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to recording paper for inkjet recording.

Conventional configuration and its problems Recording using the inkjet method is a method of recording with less noise.
Colorization is easy4], high-speed recording is possible,
It has attracted attention in recent years because it can use plain paper, and its application to various facsimile printers is expanding. It is generally said that plain paper can be used as the recording paper used in inkjet recording methods, but this does not mean that all the common papers widely used in the world can be used. requires that the paper itself meet some conditions. Under these conditions, you can make a skewer that holds the following items.

(1) It has excellent ink absorption properties, and ink dots attached to the paper surface can be quickly absorbed into the paper.

(2) It is possible to suppress the spread of ink dots on the paper surface.

Condition (1) is the same as that (1iii) of inkjet recording paper.
L is the most basic condition that must be met.

Condition (2) is a necessary condition for obtaining a vivid recorded matter, and it is possible to increase the reflection density of the recorded matter by preventing the ink dot from spreading.

These conditions (1) and (2) are the basic conditions, but in addition to them, (3) the ink should not penetrate too much in the depth direction, and (4) the paper should be of good quality. (5) The paper has excellent water resistance4.
Conditions such as 4 are required. Condition (3) was derived from the fact that the reflection density of a recorded material is determined almost entirely by the surface of the paper, so if the penetration in the depth direction is too large, the reflection density cannot be increased.

Regarding inkjet recording paper having the conditions mentioned above, JP-A-52-74340 and JP-A-5
2-53012, JP 53-49113, JP 65-5830, JP 55-1182
There is Publication No. 9.

Furthermore, recently coated paper-type recording paper made from a combination of a water-soluble polymer binder and a white filler has been developed (1).
Many proposals have been made to satisfy condition (2). For example, JP-A-55-150395, JP-A-55-146786, JP-A-55-1441.
Publication No. 72 and Japanese Unexamined Patent Publication No. 56-109783 are such examples. In addition, Japanese Patent Application Laid-Open No. 5
No. 7-38185 describes an inkjet recording paper containing polyvinylpyrrolidone or a polyvinylpyrrolidone-vinyl acetate copolymer as a surface sizing agent for inkjet recording or a binder for coating.

However, all of these inventions relate to recording paper suitable for water-based inkjet inks, and are not suitable for oil-based inkjet inks. That is,
If oil-based ink is used to record on these recording papers, the recording properties will deteriorate significantly due to ink-absorbent lines.

OBJECTS OF THE INVENTION The present invention aims to improve such conventional recording paper and provide an inkjet recording paper that is suitable for oil-based inkjet ink, is capable of high-density recording, and has excellent water resistance.

DESCRIPTION OF THE INVENTION The present invention provides an inkjet recording paper suitable for two purposes by using a resin that is insoluble in water and soluble in organic solvents as an inder. An embodiment of the invention will be described in detail.

The most widely used oil-based inks for inkjet are toluenes, and ethers such as ethyl cecile solve.

A)Reco-)V classes such as meknol, propatool, and citanol; glycols such as 17-ol and propylene glyconyl; amines and amides.

N[converted pyrrolidone and the like are used as necessary.

In view of these circumstances, the present inventor developed a coated paper using a binder resin that is soluble in these solvents in the coating layer.

In the present invention, a coat type recording paper is proposed, and an aqueous emulsion type polymer is generally used as the binder resin of the coating layer.

Examples include polyvinyl acetate, ethylene, vinyl acetate copolymer (ethylene content 30% or less), styrene resin, nutylene. Acrylic copolymer, acrylic acid Nether, aqueous shellac, vinyl acetate. Monthly rates for acrylic copolymers, polyacrylamide, etc.

A feature of these resins is that they form a film with good water resistance after drying.

In addition, as white pigments or fillers used at the same time,
Clay, talc, calcium carbonate, calcium sulfate, calcium silicate, zinc oxide, kaolin, aluminum silicate, magnesium silicate.

There are acid clay, activated clay, magnesium oxide, magnesium carbonate, aluminum oxide, silica, etc., and these can be widely used.

In the present invention, the coating layer binder is selected depending on the type of oil-based ink used, but the most important point is to use a binder that dissolves or swells with the ink solvent.

The key is to select the ink resin. As a result, a new absorption mechanism is added to the water absorption by the capillaries formed in the gaps between the white fillers, resulting in excellent ink absorbency. At the same time, the binder traps ink and enables high-density recording.

The present invention will be explained in more detail below while showing experimental data.

Inkjet recording was performed using an on-demand printing head with a nozzle diameter of 40 μm.

The amount of ink ejected can be varied from 100 to 260 by controlling the applied voltage.
It was recorded in 7 steps between v and 6 pieces/fake. The discharge amount t per unit area at each stage in the case of medium color is as follows. 1st stage, 2.6X10-400/cnf,
2nd stage, 4.7Xlσ4 Co, 2, 3rd stage.

6.4 X 10-'CC/, 4th stage, 7.0X
10-4CC7cnf1n 5th G floor, 7.9 X 10'”/7, 6th
G floor, 8.7X10-4CC7,,1 7th stage,
9.4X10-4C0/. In addition to these recordings, recording was also conducted at a rate of 2 lines/πm.

The evaluation of recorded materials consisted of: ■ Measuring the reflection density at the south exit of the 7th stage, ■ Determining at what stage ink flow occurs in order to know the extent of ink flow and bleeding (this indicates the absorbency of the paper), ■ Measurement of how many seconds it takes for the recording liquid to become apparently dry in the seventh stage. (2) Measurement of the area ratio of the recorded matter in the first stage when recording was performed at a rate of 2 lines/mm (this indicates the degree of spread of ink dots, so-called blurring).

[Example 1] A coating solution consisting of polyvinyl acetate/L/ (10% emulsion of binder resin component) and twice the amount of calcium acetate was dispersed by stirring with a fan, and a wire bar was applied to a commercially available double-quality paper. It was painted using. After coating, it was dried and then calender rolled to produce a glossy recording paper.

Inkjet recording was performed on recording paper using the method described above.

The ink used was black ink (A
) and black ink (B) whose main solvent is methyl alcohol,
For comparison, a black ink containing ethyl cellosolve as the main solvent (I used RI, water-based black ink (I)) is shown below.

The results are shown in Table 1.

Table 1 This recording paper is most suitable for water-based ink (D) in terms of ink absorption time, recording density, blur characteristics, etc., but it is excellent for oil-based inks (A), (B), and (C). It shows that it is a characteristic. This difference in recording characteristics clearly depends on whether or not the binder resin is dissolved in the solvent.

[Example 2] Real 7A! Example 1 In the same manner as in Example 1, a recording paper consisting of an acid ester copolymer (acrylic acid ester) as a binder and silica was prepared. Similarly, ink (A), (B), (C), (D
) The results of the recording are shown in Table 2.

Table 2 Acrylic ester copolymer binder is oil-based ink (A
), (B), and (C), but water-based ink (
It turns out that D) cannot be used.

Effects of the Invention As described above, the present invention is an inkjet recording paper using a binder resin that is insoluble in water and soluble in organic solvents as a coating binder, and has a very short absorption time and a high recording density compared to oil-based inks. This makes it possible to produce recording paper that has excellent recording properties with high curvature and less blur. In the present invention, since an oil-based ink and a water-resistant binder are used, the recorded matter has excellent water resistance. This is the most superior point compared to conventional recording paper using water-soluble ink and water-soluble polymer.

Claims (2)

[Claims] (1) An inkjet recording paper characterized by having a coating layer containing as a binder a resin that is insoluble in water and soluble in organic solvents. (2) The inkjet recording paper according to claim 1, wherein an aqueous emulsion type polymer is used as the water-insoluble but organic solvent-soluble resin.