JP3228416B2 - Inkjet recording method - Google Patents

Description

The present invention relates to a so-called oil-based ink, that is, an ink in which a dye or a pigment is dissolved or decomposed as a colorant in a nonvolatile hydrophobic organic solvent, or a so-called solvent. Ink, i.e., using a hydrophobic ink such as an ink in which a dye or pigment is dissolved or dispersed as a colorant in a volatile organic solvent, used for an ink jet printer, and a water-resistant sheet was used as a support. The present invention relates to a recording sheet, and provides a clear, high color density and water-resistant printer.

[Problems to be solved by conventional technology and invention]

Technical development of high-quality color hard copy of various recording methods including ink-jet is in progress.

Inkjet printers are quiet, can easily obtain high-quality color images at high speed, and have low running costs.

Inkjet printers use color,
It is divided into full color and monochrome. Also, the type of ink can be changed depending on the application. Broadly classified, water-based ink, oil-based (based on non-volatile hydrophobic organic solvent)
Printers using various inks such as inks and solvent inks (based on volatile solvents) have been developed and used.

A so-called oil-based ink is an ink in which a dye or a pigment is dissolved or dispersed as a colorant in a nonvolatile hydrophobic organic solvent. The ink and the hard copy image are not water-soluble and have excellent water resistance. The ink of the image is not likely to be melted by rain or the like, and is suitable for use in severe environmental conditions, such as outdoor advertisements, where the requirements for weather resistance are strict. These hydrophobic inkjet images are expected to be used for outdoor large area advertisements, kanbans, posters and the like.

Solvent ink is an ink in which a dye or a pigment is dissolved or dispersed as a colorant in a volatile hydrophobic organic solvent.Since the print is fixed by drying, it can be applied to a non-absorbable material such as metal and glass. Used for printing.

The use of aqueous inks in which a water-soluble dye is dissolved in water and a water-soluble organic solvent is easy to handle and can be printed at high resolution on paper, so it is used as a printer or copier for hardcopying documents and images. ing.

Since the solvent ink uses a volatile organic solvent, the solvent evaporates from prints and images, so that problems such as odor and safety have been pointed out.

On the other hand, an aqueous inkjet printer using a water-soluble dye as a coloring material is easy to handle, but has water resistance,
It has a weak storage property and is hardly used for applications in harsh environments such as outdoors.

In addition, oil-based inkjet printers that are expected to be used in harsh environments such as outdoors, even if the hydrophobic ink has water resistance and light resistance, unless a water-resistant sheet is used as a support. Is less useful for actual outdoor display.

Regardless of whether it is water-based or hydrophobic, an ink-jet image using a dye has limitations in light resistance, dark fading, and the like, and image fading is inevitable.

Since a solvent can be selected from a wide range for the hydrophobic ink, it is easy to use various organic and inorganic pigments as coloring materials. Therefore, it is said that fading of an image can be extremely reduced as compared with ink jet using a dye.

The recording sheet for aqueous inkjet, for example, using cellulose pulp as a main raw material, a paper of low sizing degree such as Stekigt sizing degree of 15 seconds or less, talc, calcium carbonate, paper containing an inorganic pigment such as silica internally added. As a result, a recording sheet having good drying properties was obtained.

Further, by providing a hydrophilic ink receptive coating layer on a high-size paper, a plastic film, a synthetic paper, or the like as a base material, a water-based inkjet recording sheet capable of obtaining a good image is obtained. . Such a water-based inkjet recording sheet has a high print density of the ink, a dot having a shape close to a circle, and good uniformity in order to improve the resolution. A receptive coating layer containing an adhesive as a main component is provided.

Recording sheets of hydrophobic inkjet printers are required to have quality such as good drying properties, high print density of ink, good uniformity, and dot shape close to a circle in order to improve resolution. You. Furthermore, for outdoor use, it is required that the image and the recording sheet have little discoloration to sunlight and wind and rain, and that the base material has strong weather resistance.

As a sheet having ordinary water resistance, paper containing a water-resistant agent internally, paper impregnated with latex, a film of a thermoplastic polymer, synthetic paper, or the like is used. Underwater elongation is used as a measure of the water resistance of the paper, and if it is 0.1% or less, it is considered satisfactory for ordinary use.

If a thermoplastic polymer film or a synthetic paper film was used as it was, the ink absorption was poor, and the ink leaked, spread, uneven absorption, or became dirty, and a high-quality hard copy image could not be obtained. .

Further, in a recording sheet in which the sizing degree of paper made of cellulose pulp as a main material is controlled or a liquid-absorbing pigment such as calcium carbonate or silica is internally added, water penetration is limited, but hydrophobic ink is used. Since the absorption behavior is completely different, the ink penetrates irregularly or rapidly, the image density is reduced, the image quality is reduced, and it is difficult to obtain a good hard copy.

In a recording sheet provided with a coating layer on paper made of cellulose pulp as the main raw material, internal and external sizing agents are used to improve and control hydrophilicity, and water penetration is suppressed to a certain extent. . However, these sizing agents are not effective for the hydrophobic ink, and therefore, the hydrophobic ink permeates, making it difficult to obtain a high-quality full-color image print.

[Means for solving the problem]

The inventors have found that the disadvantages of the prior art described above are that the light resistance of the dye of the aqueous ink is poor, the water resistance of the dye of the aqueous ink is poor, and the water resistance of the base material of the recording sheet for the hydrophobic ink is poor. That the solvent ink is unsafe and has an odor, that if the water-resistant substrate is a recording sheet for a hydrophobic ink, the absorption is insufficient, and that the recording sheet for a water-based ink has an image of the hydrophobic ink. As a result of various studies to solve the bad things, etc., using a hydrophobic ink with excellent weather resistance and water resistance, the water-resistant base material has a good receptive coating such as the resolution of the hydrophobic ink It has been found that these problems can be solved by obtaining a hard copy on a recording sheet provided with a layer.

 The present invention includes the following aspects.

(1) At least one surface of a water-resistant sheet having an elongation in water of 0.1% or less has an oil absorption of 30% by weight or more of the solid content of the coating layer as a main component is 70 ml / 100g or more, and is made of aluminum silicate and silica. One pigment selected and 0.15 of all pigments
The coating layer containing a water-insoluble adhesive of the proportion of times to 2.3 times or less, hydrophobic dye or pigment is dissolved or decomposed as a colorant in the ink jet recording sheet provided at a rate of 5 to 40 g / m ² An ink jet recording method using ink.

(2) Pigment with oil absorption of 70ml / 100g or more has oil absorption of 130ml / 1
The ink-jet recording method according to (1), wherein the weight is 00 g or more.

(3) The ink jet recording method according to (1), wherein the coating layer contains a waterproofing agent.

(4) The ink jet recording method according to (1), wherein the water-resistant sheet having an elongation in water of 0.1% or less is a paper internally containing a water-resistant agent.

(5) The ink jet recording method according to (1), wherein the water-resistant sheet having an elongation in water of 0.1% or less is a thermoplastic resin or synthetic paper.

(6) The ink jet recording method according to (1), wherein the pigment having an oil absorption of 70 ml / 100 g or more is silica.

(7) The ink jet recording method according to (1), (2) or (6), wherein the pigment having an oil absorption of 70 ml / 100 g or more is 50% by weight or more of the solid content of the coating layer.

(8) The water-insoluble adhesive is an acrylic ester copolymer,
(1) The ink jet recording method according to (1), comprising at least one selected from a styrene-butadiene copolymer and a vinyl acetate copolymer.

By this recording method, the receptivity of the hydrophobic ink is good, the image density on the sheet surface is high, the uniformity is good, the dot shape is circular, a high-quality image is given, and the weather resistance, especially the water resistance, is excellent. Hard copy was obtained.

In this specification, the term "water-insoluble adhesive" refers to an adhesive that is not substantially redissolved in water after forming a coating layer.

In the present invention, among the above-mentioned problems, a water-resistant sheet having an elongation in water of 0.1% or less with respect to the conventional recording sheet in terms of the poor water resistance of a paper base containing cellulose pulp as a main component. Solved by using.

In the present invention, the poor lightfastness and waterfastness of the dye of the water-based ink means that these qualities are excellent or have a great potential for improvement. Was solved.

In the present invention, when a recording sheet for a hydrophobic ink using a water-resistant thermoplastic resin as a base material is used, the problem of insufficient absorption is solved by providing a receptive coating layer at a specific ratio.

In the present invention, when an image is formed with a hydrophobic ink on a conventional recording sheet for an aqueous ink, the poor image such as the resolution of the hydrophobic ink can be solved by providing a receptive coating layer having a specific configuration. did.

As a support, synthetic paper, various plastic films,
Water-resistant paper such as paper containing pulp as a main component and internally added a water-proofing agent or paper impregnated with latex can be used.
In particular, it is preferable to use a monolayer or biaxially stretched multilayered synthetic paper containing a polyolefin containing an inorganic pigment as a main component. The thickness of the support is 10 to 200 μm, and the basis weight is 10 to 200 g /
m ² is preferred.

Oil absorption is 70ml / 100 which is the main component of ink receptive coating layer
As pigments of g or more, silica and aluminum silicate can be used.

A pigment having an oil absorption of 70 ml / 100 g or more, preferably 130 ml / 100 g or more is used. If only a pigment having an oil absorption of less than 70 ml / 100 g is used, the ink receptivity and drying property will deteriorate, causing ink bleeding, poor absorption, and poor image quality.

As the water-insoluble adhesive, which is another main component of the coating layer of the present invention, various polymers can be used as an aqueous emulsion polymer or a solution. Acrylate copolymers and styrene-butadiene copolymers are particularly preferred, but other polymers such as vinyl acetate copolymers can also be used. The desirability of being water-insoluble and hydrophobic is apparent from the use form of the recording sheet.

It does not matter if a water-soluble adhesive is used in combination. As the water-soluble adhesive, starch, polyvinyl alcohol, etc., which are conventionally known as pigment coating adhesives,
Can be used.

The composition of the main component of the coating layer of the present invention has an oil absorption of 70 ml / 100.
The main component is 30% by weight or more of a pigment of g or more and a water-insoluble adhesive in a ratio of 0.15 to 2.3 times the pigment. If the pigment having an oil absorption of 70 ml / 100 g or more is less than 30% by weight of the solid content of the coating, a coating layer having substantially no voids will be formed, and the liquid absorption of the hydrophobic ink will be small, and the image resolution will be low. And the drying property is impaired. Especially lipophilic and oil absorption 70
The amount of the pigment of at least 100 ml / 100 g is preferably at least 30% by weight of the solid content of the coating layer, more preferably at least 50% by weight.

The water-insoluble adhesive is 0.15 of pigment with oil absorption of 70ml / 100g or more.
It is preferable to mix them in a ratio of 2 times or more and 2.3 times or less. 0.1
If it is less than 5 times, the effect of bonding will be insufficient. When it exceeds 2.3 times,
Impairs liquid absorption and drying properties.

In order to improve the water resistance of the coating layer, various water-resistant agents such as an epoxy-based or melamine-based adhesive may be used in combination as long as the image is not affected.

Generally, the coating amount of the ink receptive coating layer is 5 to 40 g / m ² ,
Preferably from 20 to 40 g / m ^2. If the amount is too small, the ink absorbency decreases, and the drying and fixing properties of the image decrease. On the other hand, if the layer is too thick, it is not only uneconomical, but also causes a decrease in the strength of the coating layer.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to examples.
In Examples, “parts” indicates “parts by weight of solid content”.

Example 1 Paint-2 was prepared as an aqueous solution / dispersion having a solid content of 30% by weight, and a uniaxially and biaxially stretched synthetic paper having a polypropylene and an inorganic pigment as main components (Oji Oil Chemical Synthetic Paper Co., Ltd.) : YUPO SGG110) on one side at a solid content of 30 g / m ² and dried to obtain a recording sheet.

Paint-2 Aluminum silicate (Versilex Degussa K.K .: Oil absorption 170ml / 100g) 100 parts Acrylic ester-styrene copolymer emulsion (Movinyl 731 Hoechst Gosei Co., Ltd.) 50 parts Polyvinyl alcohol (NL05 Nippon Gohsei Co., Ltd.) 10 parts Example 2 Paint-3 was prepared as a toluene solution having a solid content of 20% by weight, and a mono- or biaxially stretched multi-layer synthetic paper containing polypropylene and an inorganic pigment (Oji Yuka Synthetic Paper Co., Ltd.) : FPG15
0) coated on one side at a solid content of 30 g / m ² and dried,
A recording sheet was obtained.

Paint-3 Silica (Mizuka Seal P363 Mizusawa Chemical Co., Ltd .: Oil absorption
130 parts / 100 g) 100 parts Acrylic ester copolymer (Paraloid B82 Rohm & Haas Co., Ltd.) 50 parts Comparative Example-1 Paint 4 was prepared as an aqueous solution / dispersion having a concentration of 35% by weight. Basis weight 104.5 g / m coating on one surface of woodfree paper ² at a rate of 30 g / m ² by solid content, and dried to obtain recording sheet.

Paint 4 Kaolin (UW90 Engelhard: Oil absorption 46ml / 100
g) 100 parts Polyvinyl alcohol (NL05 Nippon Synthetic Chemical Co., Ltd.) 20 parts Comparative Example-2 Paint-5 was prepared as an aqueous solution / dispersion having a concentration of 35% by weight. Basis weight 64 g / m coating on one side of the ² high-quality paper with solids at a rate of 25 g / m ^2, and dried to obtain recording sheet.

Paint-5 Heavy calcium carbonate (P-10 Shiraishi Kogyo Co., Ltd .: Oil absorption
26ml / 100g) 100 parts Polyvinyl alcohol (NL05 Nippon Synthetic Chemical Co., Ltd.) 20 parts Comparative Example-3 Mono- or biaxially stretched multi-layer synthetic paper containing inorganic pigment (Oji Yuka Synthetic Paper Co., Ltd .: FPG150) ) Was used as a recording sheet.

Using a hydrophobic dye ink obtained by dissolving 5 parts of an oil-soluble dye (Oil Blue 615: manufactured by Orient Chemical Industries) in 95 parts of alkyl naphthalene (KMS113 Kureha Chemical Co., Ltd.), using a commercially available piezo-type inkjet printer Then, printing was performed on the recording sheets of Examples, Proportional Examples, and evaluated on a 5-point scale.

Image evaluation The color density was measured using a Macbeth density system.

 The sharpness and dryness of the image were sensory-evaluated visually and tactilely.

The water resistance of the recording sheet was evaluated by sensory evaluation after immersing the sample in water for 30 minutes.

The water resistance of the print was determined by immersing the sample in water for 30 minutes and then visually evaluating the outflow of color by sensory evaluation.

Table 1 shows the evaluation results. It was divided into five stages: "excellent", "good", "normal", "poor", which is a problem for use, and "unusable", which had serious drawbacks.

[Effects of the Invention] The ink jet recording sheet of the present invention has a strong surface, good image uniformity, high color density of the image, excellent image vividness, excellent support and the entire image. The present invention enables a high-resolution inkjet printer that eliminates the drawbacks of the conventional method of obtaining a print having high water resistance and weather resistance.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-64-36478 (JP, A) JP-A-62-278808 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41M 5/00

Claims (8)

(57) [Claims] 1. A method according to claim 1, wherein at least one surface of the water-resistant sheet having an elongation in water of 0.1% or less has a solid content of a coating layer as a main component.
A coating layer containing 30% by weight or more of oil absorption of 70 ml / 100 g or more, and containing one kind of pigment selected from aluminum silicate and silica, and a water-insoluble adhesive in a proportion of 0.15 to 2.3 times the total pigment. An inkjet recording method comprising using a hydrophobic ink in which a dye or pigment is dissolved or dispersed as a colorant on an inkjet recording sheet provided at a ratio of 5 to 40 g / m ² . 2. A pigment having an oil absorption of 70 ml / 100 g or more has an oil absorption of 1 or more.
2. The ink jet recording method according to claim 1, wherein the amount is 30 ml / 100 g or more. 3. The ink jet recording method according to claim 1, wherein the coating layer contains a waterproofing agent. 4. The ink-jet recording method according to claim 1, wherein the water-resistant sheet having an elongation in water of 0.1% or less is a paper internally containing a water-resistant agent. 5. The ink jet recording method according to claim 1, wherein the water-resistant sheet having an underwater elongation of 0.1% or less is a thermoplastic resin or synthetic paper. 6. The ink jet recording method according to claim 1, wherein the pigment having an oil absorption of 70 ml / 100 g or more is silica. 7. The ink jet recording method according to claim 1, wherein the pigment having an oil absorption of 70 ml / 100 g or more is 50% by weight or more of the solid content of the coating layer. 8. The ink jet recording method according to claim 1, wherein the water-insoluble adhesive contains at least one selected from an acrylate ester copolymer, a styrene-butadiene copolymer, and a vinyl acetate copolymer.