JPS62218180A - Ink jet recording sheet - Google Patents

Abstract

PURPOSE:To prevent each ink used in multicolor recording from flowing over, to obtain clear images free of blur and provide high-speed recordability, by incorporating highly swellable gelatine having a specified degree of swelling with water into an ink-receiving layer. CONSTITUTION:Gelatine having a degree of swelling with water of 30-60 times is incorporated in an ink-receiving layer provided on a base. Although a sufficient effect can be obtained by solely using highly swellable gelatine in the ink-receiving layer, one or more other water-soluble high molecular weight substances such as starch and oxidized starch may be jointly used, the amount of which is preferably 20-0.05pts.wt. per 1pts.wt. of highly swellable gelatine. Where the ink-receiving layer is required to be resistant to water, it is preferable to jointly use one ore more hardening adjuvants such s formaldehyde and a polyaldehyde, the amount of which is preferably 50-5wt% based on the total amount of highly swellable gelatine and the water-soluble high molecular weight substances.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inkjet recording sheet, and relates to an ink-receiving layer provided for forming an image using ink.
The present invention relates to an inkjet recording sheet that has excellent absorption capacity, provides multicolor recording with little bleeding and excellent color development.

(Prior Art) The inkjet recording method is rapidly attracting attention because of its low noise, high-speed recording, and OT capability of multicolor recording.However, when performing multicolor recording.

Since ink is ejected from two or more ink nozzles and two or more ink droplets overlap at one point on the recording surface, it is important how to stop the ink droplets from being received on the recording layer. Due to ink ejection head clogging and stability,
The dye is used dissolved in a water-bathable medium at a very low concentration, and the dye involved in color development is stopped by the ink-receiving layer (recording layer), and at the same time the water-bathable medium is quickly diffused into the support. Retention or absorption is required. Normally, the thickness of the ink receiving layer on the support, that is, the film involved in ink absorption, is around 10 μm, whereas the diameter of the ink droplet ejected from the nozzle is 50 to 100 μm, which is 5 to 10 μm.
It's twice as big. Moreover, it is required to hold two or more droplets on the same surface in a very short period of time, within several milliseconds, with a receiving layer including a support.

Therefore, paper to which the ink liquid has been added has a size similar to that of high-quality paper,
Multicolor inkjet recording is performed by dropping or spraying ink onto a support that has little or no diffusion absorption, such as coated paper, synthetic paper, or plastic sheet.

The ink liquid diffuses in the Z-axis direction from the position it reaches on the recording surface.
Before penetrating, it spreads in the XY axis direction of the recording surface, causing blurred images and disordered lines due to color mixing between 8A red inks.
This results in deterioration of image quality.

Therefore, supports that do not have absorbency or have low absorbency have no practical use in multicolor inkjet recording, or are only practical for use in single colors.

Many studies have been made to solve these problems. JP-A-56-80489 attempts to retain ink by providing an ink-receiving layer with a substance that dissolves or swells with ink.

Furthermore, Japanese Patent Application Laid-Open No. 55-146786 attempts to increase the ink absorption capacity by using a water-soluble polymer having a relatively high ink retention capacity.

In addition, the ink retaining ability according to these inventions has a high color image density.

4 or more ink droplets at one point on the recording surface
- In case of overlapping, or when the recording speed is increased, Ki2 naturally lacks ink absorption capacity, and each color overflows, causing blurring, resulting in poor clarity of one image, poor reproduction of halftones, and blurring of one color. Records become unsuitable for practical use. Furthermore, it takes a long time to set the ink, making it impossible to achieve the original purpose of high-speed recording. JP-A No. 57-173194 has a particle size of 0,
A recording layer is provided using a water-absorbing resin with a thickness of 1 to 100 μm in combination with a binder, and is used for inkjet recording. However, although water-absorbing m fat has a very large water-absorbing capacity of 50 to 1000 times, the water-absorbing time and Ijl wet-opening time may reach the time, which does not match the absorption time in inkjet recording. In addition, it is soluble in non-aqueous media.

Although it is easy to form a gold film, it has the disadvantage that it is very difficult to form a coating in an aqueous medium, although it can be pulverized to a small particle size.

(Problems to be Solved by the Invention) The purpose of the present invention is to increase the absorption capacity of IK ink in the recording layer, prevent overflow of each ink in multicolor recording,
To provide an inkjet recording sheet having a clear image without bleeding and excellent one-color reproducibility.

Secondly, it has a high ink retention function and a good ink set.
An object of the present invention is to provide a recording sheet suitable for high-speed inkjet recording.

(Means for Solving the Problem) The present inventor discovered a substance with a large function of receiving, retaining, and absorbing ink droplets, and incorporated it into the ink receiving layer of an inkjet recording sheet to perform multicolor recording. Each ink's oats (-flow t-prevents) and provides clear images without smearing.

Furthermore, we succeeded in obtaining an inkjet recording sheet that also has high-speed recording properties.

That is, according to the present invention, in an inkjet recording sheet in which ink-receiving J buds are provided on a support.

Provided is an inkjet recording sheet characterized by containing gelatin, which has a high swelling ability that is 30 to 60 times more swellable than water, in an ink-receiving layer. Gelatin (hereinafter referred to as highly swellable gelatin) has, for example, the properties shown in Table 1. It is suitable for use in inkjet recording sheets and satisfies ink absorption capacity and ink set time (high speed), is suitable for multicolor recording, and also satisfies characteristics such as light resistance and water resistance of recorded images. be.

Although highly swollen gelatin can be used alone in the ink-receiving layer provided in the inkjet recording sheet of the present invention, sufficient effects can be obtained; however, other water-soluble polymers such as starch, oxidized starch, phosphate starch, cationic Various starches such as starch and their derivatives, modified products, polyvinyl alcohol, carboxy-modified polyvinyl alcohol,
Cation-modified polyvinyl alcohol, acetylated polyvinyl alcohol, styrene-maleic anhydride coheavy metal and its ammonium modified product, polyvinyl alcohol-acrylic ester-acrylic acid copolymer, polyvinyl alcohol-acrylamide-acrylic ester-acrylic acid One type or two or more types of copolymers and ammonium-modified products thereof may be used in combination, and the proportion thereof is preferably 20 to 0.05 parts by weight based on the portion of highly swellable gelatin 1N.

Furthermore, when water resistance of ink acceptance I- is required, formalin, polyvalent aldehyde, dialdehyde starch, polyethyleneimine, polyamide polyamine, polyamide polyamine epoxy resin.

It is desirable to use one type or two or more types of curing aids such as the following. The ratio is preferably 50 to 5 ffiffiffi' based on the total amount of highly swollen gelatin and water-soluble polymer. In this case, it is also possible to improve the plating of the ink-receiving layer, improve fingerprint resistance, etc.

In addition to the highly swellable gelatin and water-soluble polymer of the present invention, an inorganic pigment is used as a filler in the ink-receiving layer of the inkjet recording sheet of the present invention, which improves ink absorption and whiteness.

It is effective in improving contrast, and furthermore, by controlling the particle size of the pigment, the dot size can be controlled. Pigments that can be used for this purpose include, for example, calcium carbonate, clay, zeolite, talc, barium sulfate, zinc chloride LVi, titanium oxide,
There are inorganic and organic pigments such as synthetic aluminum silicate, synthetic aluminum/magnesium silicate, synthetic magnesium silicate, aluminum hydroxide, synthetic silicic acid, diatomaceous earth, magnesium hydroxide, polystyrene or polyethylene fine powder, and urea resin fine powder. The appropriate amount of these is 0 to 10 parts by weight per 1 part by weight of highly swollen seratin and water-soluble polymer.

Other additives that form the ink receiving layer include:

These include fixing agents for ink dyes, ultraviolet absorbers that improve the light resistance of ink, pigment dispersants, pigment setting aids, antifoaming agents, preservatives, fluorescent whitening agents, viscosity stabilizers, etc. These can be used depending on the purpose. Paper, synthetic film, plastic film, etc. can be used as the support.

Providing an ink-receiving subbing layer containing highly swellable gelatin is effective for improving uneven absorption of ink, improving density, density, and contrast.

Ink absorption can also be improved.

For these purposes, inorganic pigments, organic pigments, plastic pigments with a particle size of 0.2 to 15 μm, such as calcium carbonate, clay, zeolite, talc, barium sulfate, zinc chloride.

Titanium white, synthetic aluminum silicate, synthetic magnesium silicate, synthetic aluminum/magnesium silicate, synthetic silicic acid, diatomaceous earth, polyethylene fine powder, polystyrene fine powder, urea resin fine powder, etc. per 1 noii part of binder 5 to 20 Esobe mixed coating materials can be used. As the binder, the crystal-swollen gelatin of the present invention and the water-soluble polymer described above may be used.

Is the coating amount of the undercoat layer 2-20 f/l? is appropriate.

It is desirable to balance the pigment with the ink-receiving layer by changing the particle size of the pigment and the ratio of the pigment to the binder.

The ink acceptance I@ of the present invention is 0.5 to 20 coated per side.
9, the preferred range is 2 to 1597%. Coating is not limited to only one side of the support, but can also be applied to both sides if necessary.

Generally used coating methods and coating equipment ab
-Can be used. For example, an air knife coater, a blade coater, a graphia coater, a curtain coater, a bar coater, a roll coater, a size press coater, a Kate roll coater, etc. can be used. After coating, it is desirable to perform calender treatment as necessary to smooth the coated surface.

Further, heat treatment may be performed at an appropriate temperature in order to develop water resistance. Note that gelatin becomes jelly-like at temperatures below 30°C, so appropriate temperature control is required.

Measurement of vF properties and characteristics in the present invention was carried out under the following conditions.

Ink-absorbing IBM 3852 color inkjet printer was used to print two mixed colors, and at this time, each ink did not bleed (a case where the ink was completely absorbed into the ink-receiving layer after 1 second is marked as ○).

This applies to Examples 1-3 and Comparative Examples 1-2.

Ink set time Example 4 Applied to Comparative Example 3. Comparison f! AI 3 to 61
11 specific methods have been described.

Immerse the water-resistant recording sheet in running water, and after 5 minutes, ink receiver Fl! If the layer has peeled off or the bath has come out, it is marked as ×.

A light-fast IBM 3852 color inkjet printer is used to perform peta printing, and exposure to a fade meter is performed for 24 hours, and a black residual rate of 50 or less is marked as x.

Dot diameter Print with a Canon A1210 inkjet printer, and measure the dot diameter of the black part with a 100x loupe.

Nijimi IBM 3852 color inkjet printer performs double-print peta printing, observing the flow of ink in the color mixing area, and later checking the ink liquid 7 that has hit the ink receiving NK.
The case where 8 is flowing out is marked as ×.

(Actual tM example) Example 1 100 Hrls of synthetic aluminum silicate with an average particle size of 7 μm, 104 [1100 parts of carboxy-modified polyvinyl alcohol, gelatin D] on 64 tons/- of commercially available high-quality paper.
100 parts of 104 solution and 130 yen parts of polyamide polyamine engineered poxy tree T4 of 20 series.

Paint with a solid content of 25 ml on one side with a solid content of 152/f
? Coat with a Meyer bar and dry.

The properties were evaluated using the method described above, and the results shown in Table 2 were obtained.

Example 2 Synthetic silica (p-78 manufactured by Mizusawa Chemical Industry Co., Ltd.) 10 parts (1 part, 20 parts of polyvinyl alcohol-methyl methacrylate-acrylic acid copolymer) was placed on commercially available synthetic paper 60 μm.
100 parts of gelatin solution, 300 parts of 154 fat solution of gelatin and 20 parts of polyamide polyamine engineered poxy ftttli &
One side of the paint with a solid content of 20 yen consisting of the loo part
It was coated with a 0 f/rrl Mayer bar, dried, and evaluated for characteristics, and the results shown in Table 2 were obtained.

Example 3 First, 100 parts of synthetic silica (Jilton LP105 manufactured by Mizusawa Chemical Co., Ltd.) and 50 M of calcium carbonate (PC manufactured by Shiraishi Calcium Co., Ltd.) were placed on commercially available high-quality paper 642 paper.
A paint with a solid content of 204 made of 200 parts of a 10% solution of polyvinyl alcohol was coated with a solid content of 5 f///mayer par on one side, dried to form an undercoat layer, and then synthetic silicic acid with an average particle size of 5 μm was applied on top of this. Solid content consisting of 0 parts of aluminum IC), 100 parts of 104i liquid of polyvinyl alcohol-acrylamide-acrylic acid ester-acrylic acid copolymer, gelatin (100 parts of C115'1 liquid and 40 parts of 20% polyamide polyamine engineered poxy IN resin) 28 pieces of paint was applied with a solid content of 1°t/rrl on one side using a Mayer bar, dried, and the properties were evaluated, and the results shown in Table 2 were obtained.

Example 4 A 1596 watered liquid of gelatin (1) was coated on a commercially available polyester film (trade name: Mitsubishi Diafoil 100 μm corona treated product) at a solid content of 8 f/d and dried to obtain a transparent sheet for inkjet recording. The results are shown in Table 2.

Comparative Example 1 The results shown in Table 2 were obtained in the same manner as in Example 1, except that commercially available gelatin (5) was used in place of gelatin 0.

Comparative Example 2 The results shown in Table 2 were obtained in the same manner as in Example 1, except that gelatin (gelatin C instead of DJ) was used.

Comparative Example 3 A transparent sheet for inkjet recording was obtained in the same manner as in Example 4, except that gelatin (4) was added.

Canon A1210 on the recording sheets of Example 4 and Comparative Example 3
Using a color inkjet printer, a total of 7 colors can be printed, including single colors of cyan, yellow, magenta, and black, and mixed colors of cyan and yellow, cyan and magenta, and yellow and magenta.
After recording the color in full dots, place a filter paper on the recording surface and
A pressure of kV'cd was applied for 2 seconds, and the time until no ink marks were left on the filter paper was measured, which was defined as the ink setting time. The results are shown in Table 2.

Table 1 Gelatin properties Note 1) In a container filled with distilled water at 20℃.

Only the upper part is covered with wire mesh of 325 mesh.
Submerge a cylindrical container with its head protruding above the water surface, and pour 1f of powdered gelatin that has passed a 50-mesh analytical sieve through the upper opening of the cylindrical container.
The cylindrical container is pulled up in seconds, and the amount of water absorbed by the 12 gelatin added is measured to determine the moisture content. Note 2) Measured using a BIαh type jelly strength meter.

Note 3) d (11 constant) determined by B100m viscometer.

Table 2 (Effects of the Invention) As is clear from the results shown in Table 2, the recording sheets obtained in Examples 1 to 4 according to the present invention had poor ink absorption, ink bleeding, and ink set time. Although it is excellent, the comparative sheet made by the prior art cannot satisfy each characteristic.

Claims (1)

[Claims] An inkjet recording sheet comprising an ink-receiving layer provided on a support, the ink-receiving layer containing gelatin having a swelling degree of 30 to 60 times with respect to water.