JPS59192589A - Ink jet recording paper - Google Patents

Abstract

PURPOSE:To obtain an ink jet recording paper capable of maintaining a favorable hue and having a sufficient coat strength, by a method wherein a system comprising a white filler subjected to a surface treatment with a specified organic substance and comprising a water-soluble high polymer as a binder is used as a coating material. CONSTITUTION:An organic substance having a nitrogen atom is adhered to the surfaces of a white filler such as silica. A system comprising the thus treated white filler and comprising as a binder a water-soluble high polymer consisting of polyvinyl pyrrolidone (PVP), polyvinyl pyrrolidone-polyvinyl acetate copolymer (PVP/PFAc), polyvinyl alcohol or a mixture thereof, is applied to a blank paper as a coating material to obtain an ink jet recording paper favorable in hue and markedly enhanced in coat strength. Particularly, when a filler containing not less than 80% of silica is used, a favorable hue and a practical coat strength can be obtained.

Description

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

2 haq, SL Conventional configuration and its problems Reasons for inkjet recording include low noise, easy colorization, high-speed recording, and the ability to use plain paper. It has been attracting attention in recent years, and its application to facsimile machines, various printers, etc. 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 several conditions.

The following conditions can be listed as such:

(1) It has excellent ink absorbency and can quickly absorb ink dots adhering to the paper surface into the inside of the paper.

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

(3) The coating must have sufficient coating strength and a satisfactory color.

Condition (1) is the most basic condition that an inkjet recording paper must have, but this condition is particularly important when a color image is to be drawn by an inkjet method.

It's yellow and cyan if you can't draw a color screen.

This is because it is necessary to create multiple colors by combining each magenta ink, and the amount of ink per unit area increases because the different color inks adhere to the same place on the paper surface.

The condition (2) is necessary to obtain the density of the recorded material, and by preventing the ink dots from spreading, the reflection density of the recorded material can be increased. Generally, the simplest way to increase the reflection density of recorded matter is to increase the dye concentration contained in the ink, but such methods require controls to prevent clogging of head nozzles and the like. Therefore, it is important that paper has these five properties.

) Also, in condition (3), if the coating strength is low, the coated surface may peel off depending on how it is handled after recording, so in order to prevent this, a method of changing the binder) was considered. However, it is difficult to maintain good color and increase coating strength.

These (' + + (21) and (3) conditions are basic conditions, but in addition to them, (4) the penetration of the ink in the depth direction is not too thick, and (6) the paper is of good quality. It is necessary to meet certain conditions such as having whiteness.The reflection density of the recorded material is determined mostly by the surface of the paper, so if the penetration in the depth direction is too thick, it will not be possible to increase the reflection density. Recording paper is generally made from bleached chemical pulp as a filler, dye, and optionally a sizing agent.

Paper is made by adding paper strength enhancers.

Regarding inkjet recording paper having some of the above-mentioned conditions, there is Japanese Patent Application Laid-Open No. 74340/1983, which describes [air permeability (sI! The ratio (air permeability/basis) of c) is ○, 3 or less, and the water-based ink for inkjet recording is 0.
004 d is dropped, the ink absorption time is in the range of 2 seconds or more and 60 seconds or less.'' A surface coating with a Steckigt size of 3 seconds or less can be achieved by applying a paint for coated paper manufacturing to paper base paper with a Steckigt size of 1 second or less obtained by internally adding a wet paper strength enhancer. ``Method for manufacturing recording paper characterized by using it as construction paper'' is described. Among these are oxidized starches, pVA, as surface sizing agents.

Galactomannan gum polyacrylamide, sodium alginate, styrene-maleic acid copolymer.

CMG and other cellulose derivatives, casein, soybean protein, etc. are described. Further, as additive sizing agents or hydrophobic substances or latexes, rosin and its derivatives, petroleum resins, phthalic acid, maleic acid and its derivatives, waxes, synthetic resin fatty acids.

Alkyl ketene dimers are described. Also, pigments,
Kaolin and calcium carbonate as fillers.

Aluminum hydroxide, satin white, titanium oxide, and urea-formalin organic fillers are described.

Furthermore, Japanese Patent Application Laid-open No. 55-5830 states, ``It consists of a support and an ink absorption layer provided on its surface, has an opacity of 66.0% to 97.5%, and an ink absorption layer of 6.0%. ``An inkjet recording sheet characterized by an inkjet recording sheet of 1.6 to 18.mm/min'',
JP-A-65-11829 states that “the following requirements (1)
An inkjet recording sheet comprising (4). (
1) Having a layer structure of two or more layers, (2) Opacity is 6
5. (3) The thickness of the outermost layer is 1. (4) The ink absorbency of the outermost layer is 1.6 to 5.5 μIJ meters/min, and the ink absorbency of the second layer is 6.5 to 60 μm.
．． 0 mm/min."

Among these are clay, talc, and diatomaceous earth as white pigments that form the ink absorption layer.

Calcium carbonate, calcium sulfate, barium sulfate.

Titanium oxide, zinc oxide, zinc sulfide, satin white, aluminum silicate, lithopone, and as binder resins, oxidized starch, etherified starch, gelatin,
Casein, carboxymethyl cellulose, hydroxyethyl cellulose, polyvinyl alcohol, and SBR latex are described.

Further, there is % JP-A No. 57-38185 which aims to achieve the conditions (1) to (4) already mentioned. In particular, polyvinylpyrrolidone (hereinafter abbreviated as Pvp) and polyvinylpyrrolidone-polyvinyl acetate copolymer (abbreviated as PVP/PVAc) are used here. This gives good color to inks using dyes.

However, the second conventional inkjet recording paper does not satisfy all the conditions shown in (1) to (6) above, and it is difficult to find one that maintains particularly good color tone and has a sufficiently thick coating strength. do not have.

OBJECTS OF THE INVENTION The object of the present invention is to obtain an ink jet recording paper which maintains good color tone and at the same time has sufficient coating strength.

1. Structure of the Invention The present invention is a coated type inkjet recording paper using as a coating agent a system in which a white filler surface-treated with an organic substance having a nitrogen atom and a water-soluble polymer as an inder are used.

Description of examples Examples of the present invention will be described in detail below.

Generally, when silica is used as a white filler and a water-soluble polymer such as polyvinyl alcohol (hereinafter referred to as PVA), cellulose, or starch is used as a binder to increase coating strength, the coating strength increases but the color changes. bad. In particular, red and blue colors are noticeably worse.

On the other hand, polyvinylpyrrolidone (hereinafter referred to as p) is used as a binder.
When PVA is used and silica is used as a white filler, the color is good, but the coating strength is lower than when PVA is used, and the ink absorption time is increased. is observed, deteriorating the recording characteristics.

In the present invention, an organic substance having a nitrogen atom is attached to the surface of a white filler such as silica, and PVP, a copolymer of PVP and vinyl acetate (hereinafter referred to as PVP) is used as a binder.
By applying a water-soluble polymer consisting of either VP, /PVAc), PVA, or a mixture thereof to base paper as a coating agent, it is possible to obtain a good color and coatability. To provide inkjet recording paper with significantly increased working strength.

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

Inkjet recording was performed using an on-demand head with a nozzle diameter of 40 μm, and each of the three inkjet heads ejected ink of three colors, cyan, yellow, and magenta. Combinations of these inks created the colors red, green, blue, and sepia.

Regarding drying time, sepia color (2
, 5X 1O-5Cc/cA) to measure how many seconds it took for the sample to appear dry after recording. Regarding the color, the magenta color, which has a noticeable difference, was visually observed, and regarding the coating strength, a relative ranking was performed using the R1 printability test.

<Example 1> The silica used in this example was Nippo Seal manufactured by Nippon Silikani Co., Ltd., and PvP was used as the binder. On the other hand, N-allyl gamma aminopropyltrimethoxysilane containing nitrogen in the molecule was used for surface treatment of silica.

First, the silica was washed several times with distilled water, dried, and then placed in a solution of the silane dissolved in distilled water for 3 minutes.
This was washed again with distilled water, heated at 130°C for 1 hour, and then heated at 130°C for 1 hour.
Those left open for 3 hours at 0°C were used. The dissolution ratio of silane to water is two types, 0.3% and 2.0%, and the treated silica is treated by repeating the above method 6 times in the above two types and 2.0% solution. Three types were used. This silica was placed in an 8% aqueous solution of PvP and made into a slurry by stirring with a fan. This was applied onto a base paper having a Steckigt size of 20 seconds or less using a wire bar, and after application, it was treated by hot air drying and surface pressing. Inkjet recording was performed on the recording paper thus produced by the method described above. The results are shown in Table 1.

The color hue and coating strength decrease in the order of A, B, and C.

11 As can be seen from the above results, when silica without surface treatment is used, the color is poor and the coating strength is also low.As for the drying time, the silica treated five times by the 0.2 factor is clearly slow. It has become. This seems to indicate that the water adsorption sites on the silica surface are considerably crushed.

Table 1 〈Example 2〉 Example 2 includes the following examples:
For this purpose, a mixed system of PVP/PVA was used.

The surface treatment of silica is as described in 2. It belongs to the person in charge.

As shown in Table 2, the results show that the untreated silica-PVA system was poor in color shade, but good in coating strength. Regarding coating strength, untreated silica-PVP/PVA (90/10)
Although the system is not good, the color is good. On the other hand, in the case of surface treatment with silica, even if PVA is mixed with pvP in order to increase the coating strength, there is very little deterioration in hue, and a recording paper with excellent coating strength and five hues can be obtained.

Table 2 <Example 3> This example is an example in which calcium carbonate was used as a filler. Toluene 13/- diisocyanate was used for surface treatment of this filler, calcium carbonate was immersed in it, washed with anhydrous benzene, and then heated in air for 80 min.
After leaving it in an oven at 0.degree. C. for 6 hours, a trial recording paper was produced in the same manner as in Example 1 using pvP/PVAC as a binder. The results were based on the evaluation in Example 1, and although the drying time was as long as 10 seconds, the color and coating strength were both A rank, and the result was not a problem for practical use.

In each of the above examples, N-
Although allyl γ-aminopropyltrimethoxysilane and toluene diisocyanate have been explained as examples, it goes without saying that nitrogen-containing substances other than the above may also be used. For example, H2NC2H4NHC3H6Si(OC
Hs)s, (CH30)3sic3H6NHCH2
(H= CH2, (CH30)ssic3H6NH,C
2H4NHCH2CH (Me is OH3 group), Me2
Si-N (copper, etc. is also possible).

In addition to silica and calcium carbonate, the fillers are also clay.

Talc, calcium silicate, or a mixture of these with silica can also provide a good color and a practical coating strength of 1.4 tons or more, but fillers containing 80 tons or more of silica are particularly good. there were. Furthermore, regarding these fillers, similar results were obtained when the surface was treated with polyurethane-based organic substances in addition to isocyanate-based fillers.

(more than the effects of the invention), 1: C, the present invention 11'lj:, pvp, P
A recording paper with a water-soluble polymer such as VP/PVAc or PVA alone or a mixture as an inverter, the surface treated with a nitrogen-containing organic substance, and a coating layer with filler. The mechanical strength also makes it possible to produce recording paper with sufficient strength.

Claims (3)

[Claims] (1) An inkjet recording paper characterized in that a white filler surface-treated with an organic substance having nitrogen atoms is used as a filler, and a system in which the filler and a water-soluble polymer are used as a binder is coated on a base paper. (2) Coho IJ -r - in which the water-soluble polymer is polyvinylpyrrolidone or polyvinylpyrrolidone and vinyl acetate. The inkjet recording paper according to claim 1, which is made of polyvinyl alcohol or a mixture thereof. (3) The inkjet recording paper according to claim 1, wherein the main component as a filler is a white filler containing at least 80% silica.