JPH03133687A - Ink jet recording sheet - Google Patents

Abstract

PURPOSE:To obtain a print of high quality and full color image by using hydrophobic ink having excellent weather resistance and water resistance, and providing a receiving coating layer having high resolution of hydrophobic ink of the image on a water resistant base material. CONSTITUTION:A coating layer containing 30 wt.% or more of a pigment having 40ml/100g or more of oil absorption degree and nonaqueous adhesive of 0.15 to 2.3 times as much as the pigment as main ingredients is provided at a ratio of 5 - 40 g/m<2> on at least one side surface of a water resistant sheet having 0.1% or less of elongation under water. Thus, the acceptance of the hydrophobic ink is satisfactory, the image density of a sheet surface is high, its dot shape is circular, high quality of image is provided, and a hard copy having excellent weather resistance and particularly excellent water resistance is obtained.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to so-called oil-based inks, that is, inks in which a dye or pigment is dissolved or dispersed as a coloring agent in a non-volatile hydrophobic organic solvent, and so-called solvent-based inks. ink, i.e.
using hydrophobic inks, such as inks in which dyes or pigments are dissolved or dispersed as colorants in volatile organic solvents;
This relates to a recording sheet used in an inkjet printer that uses a water-resistant sheet as a support, and provides a printer that is clear, has high color density, and is water-resistant.

[Prior art and problems to be solved by the invention] Technological development of high-quality color hard copies using various recording methods including inkjet is progressing.

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

Inkjet printers can be divided into color, full color, and monochrome depending on the image type.

Furthermore, the type of ink can be changed depending on the application. Printers that use various types of ink have been developed and are in use, broadly classified into water-based ink, oil-based ink (based on a non-volatile hydrophobic organic solvent), and solvent ink (based on a volatile solvent).

So-called oil-based ink is an ink in which a dye or pigment as a coloring agent is dissolved or dispersed in a nonvolatile hydrophobic organic solvent, and the ink and hard copy image are not water-soluble and have excellent water resistance. There is no risk that the image ink will dissolve due to rain, etc., making it suitable for applications that are used in harsh environmental conditions, such as outdoor advertising, where weather resistance is strict.

These hydrophobic inkjet images are expected to be used in outdoor large area advertisements, campans, posters, etc.

Solvent ink is an ink in which a dye or pigment as a coloring agent is dissolved or dispersed in a volatile hydrophobic organic solvent,
Since the print is fixed by drying, it is used for printing on non-absorbent materials such as metal and glass.

Using a water-based ink made by dissolving a water-soluble dye in water and a water-soluble organic solvent is easy to handle and can be printed on paper with high resolution, so it is used as a printer copier to make hard copies of documents and images. There is.

Since solvent inks use volatile organic solvents, the solvent evaporates from prints and images, causing problems with odor and safety.

On the other hand, water-based inkjet printers that use water-soluble dyes as coloring materials are easy to handle, but have weaknesses in water resistance and storage stability, making them difficult to use in harsh environments such as outdoors.
is rarely used.

In addition, oil-based inkjet printers that are expected to be used in harsh environments such as outdoors cannot be used unless a water-resistant sheet is used as a support, even if the hydrophobic ink has water resistance and light resistance. has little utility value for actual outdoor display purposes.

Inkjet images using dyes, whether water-based or hydrophobic, have limitations in light fastness, dark fading resistance, etc., and fading of the image is unavoidable.

Since solvents can be selected from a wide range for hydrophobic inks, it is easy to use various organic and inorganic pigments as coloring materials. Therefore, it is said that fading of images can be extremely reduced compared to inkjet using dyes.

Recording sheets for water-based inkjet use, for example, are made of cellulose pulp as the main raw material, and use paper with a low sizing degree such as a Steckigt sizing degree of 15 seconds or less, or paper that has internally added inorganic pigments such as talc, calcium carbonate, or silica. As a result, a recording sheet with good drying properties was obtained.

In addition, recording sheets for water-based inkjet that can produce good images have been obtained by providing a hydrophilic ink-receptive coating layer on a base material such as high-size paper, plastic film, or synthetic paper. . Recording sheets for such aqueous inkjet printers have high ink printing density, and in order to improve resolution, the dot shape is close to a circle, and pigments with high liquid absorption properties are used to ensure good uniformity. A receptive coating layer containing an adhesive as a main component is provided.

Recording sheets for hydrophobic inkjet printers require qualities such as good drying properties, high ink printing density and good uniformity, and the shape of the dots to be close to a circle to improve resolution. Ru. Furthermore, for outdoor use, it is desired that the image and recording sheet be less discolored by sunlight, wind and rain, and that the base material be strong and weather resistant.

Typical water-resistant sheets include paper internally added with a waterproofing agent, latex-impregnated paper, thermoplastic polymer film, and synthetic paper. The underwater elongation is used as a measure of the water resistance of paper, and if it is 0.1% or less, it is considered to be satisfactory for normal uses. Naturally, it is 0% for thermoplastic polymer films and synthetic papers.

If thermoplastic polymer films or synthetic paper films were used as they were, ink absorption would be poor, resulting in ink running, spreading, uneven absorption, or staining, making it impossible to obtain high-quality hard copy images. .

In addition, water penetration is limited by controlling the size of paper made mainly from cellulose pulp, or by adding liquid-absorbing pigments such as calcium carbonate or silica, but water penetration is limited. Since the absorption behavior is completely different,
Ink penetrates irregularly or rapidly, image density decreases, image quality deteriorates, and it is difficult to obtain good hard copies.

In recording sheets that have a coating layer on paper that is made primarily from cellulose bulbs, internal and external sizing agents are used to improve and control hydrophilicity, suppressing water penetration to a certain level. . However, these sizing agents are not effective for hydrophobic ink, and therefore, the hydrophobic ink penetrates, making it difficult to print high-quality full-color images.

[Means to solve the problem]

The present inventors have found that the above-mentioned drawbacks of the prior art, namely, the poor light fastness of the dye in the water-based ink, the poor water resistance of the dye in the water-based ink, and the poor water resistance of the base material of the recording sheet for hydrophobic ink. There are concerns about the safety of solvent inks and their odor; there are also concerns that the absorbency of recording sheets for hydrophobic inks is insufficient when using water-resistant base materials as recording sheets for hydrophobic inks; As a result of various studies to solve the problems, we have developed a product with excellent weather resistance and water resistance.
We have found that these problems can be solved by using hydrophobic ink and producing a hard copy on a recording sheet in which a water-resistant base material is provided with a receptive coating layer that provides good image resolution for the hydrophobic ink.

This means that at least one side of a water-resistant sheet with an elongation in ice of 0.1% or less is coated with a pigment as a main component having an oil absorption of 40mf/100g or more and 0.15% of this pigment. By using an inkjet recording sheet characterized in that a coating layer containing a water-insoluble adhesive at a ratio of 5 to 2.3 times is provided at a ratio of 5 to 40 g/m', a hydrophobic ink It was discovered that hard copies with good receptivity, high image density and uniformity on the sheet surface, circular dot shapes, high-quality images, and excellent weather resistance, especially water resistance, can be obtained. Ta.

Note that in this specification, the term "water-insoluble adhesive" refers to an adhesive that does not substantially redissolve in water after forming a coating layer.

Among the above-mentioned problems, the present invention solves the problem that the paper base of the conventional recording sheet, which is mainly composed of cellulose bulbs, has poor water resistance. The problem was solved by using a sex sheet.

In the present invention, the poor light fastness and water fastness of dyes in water-based inks can be replaced by hydrophobic inks, which have superior quality or have a large possibility of improvement, and can achieve high image quality equivalent to water-based inks. I solved it by doing

In the present invention, the problem of insufficient absorbency when using a hydrophobic ink recording sheet based on a water-resistant thermoplastic resin was solved by providing a receptive coating layer in a specific ratio.

In the present invention, when an image is formed using a hydrophobic ink on a conventional recording sheet for water-based ink, the poor resolution and other problems of the image with the hydrophobic ink can be solved by providing a receptive coating layer with a specific configuration. did.

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

Oil absorption, which is the main component of the ink receptive coating layer, is 40mjl
! /100g or more of the pigment is particularly preferably a lipophilic pigment. Calcium carbonate, kaolin and the like, particularly light calcium carbonate and calcined kaolin, are preferred. Hydrophilic materials can also be used, such as aluminum hydroxide, silica, aluminum silicate, calcium silicate, and the like.

Furthermore, microspheres made of organic pigments, such as urea-formalin resin, polystyrene, polymethyl methacrylate, and other polymers whose glass transition point is above room temperature, can also be used.

Oil absorption is over 40ml/100g, especially 70mj! /1
It is preferable to use 00 g or more of pigment.

If only a pigment with an oil absorption of less than 40 ml/100 g is used, the ink receptivity and drying properties will be poor, the ink will bleed, malabsorption will occur, and the image quality will deteriorate.

As the water-insoluble adhesive, which is another main component of the coating layer of the present invention, various polymers can be used in the form of an aqueous emulsion polymer or a solution. Acrylic acid ester copolymers and styrene-butadiene copolymers are particularly preferred, but other polymers such as vinyl acetate copolymers can also be used. It is clear from the manner in which the recording sheet is used that it is desirable to be water-insoluble and hydrophobic.

It is okay to use water-soluble adhesives together.

As the water-soluble adhesive, those conventionally known as adhesives for pigment coating, such as starch and polyvinyl alcohol, can be used.

The composition of the main component of the coating layer of the present invention has an oil absorption of 40mf/
100g or more of pigment with 30% or more by weight and 0% of this pigment.
．． The main component is a water-insoluble adhesive at a ratio of 15 to 2.3 times. If the coating solid content is 30% by weight or less of a pigment with an oil absorption of 40 ml/100 g or more, a coating layer with virtually no pores will be formed, and the liquid absorption of the hydrophobic ink will be reduced, resulting in a decrease in image resolution. decreases, impairing drying properties.

In particular, the amount of the lipophilic pigment having an oil absorption of 40rd/100g or more is preferably 30% by weight or more of the solid content of the coating layer, and more preferably 50% by weight or more.

Does water-insoluble adhesive have an oil absorption of 40mf? /100g or more of pigment is preferably blended at a ratio of 0.15 times or more and 2.3 times or less. If it is less than 0.15 times, the adhesion effect will be insufficient. If it exceeds 2.3 times, liquid absorption and drying properties will be impaired.

In order to improve the water resistance of the coating layer, it is permissible to use a water resistance agent for the adhesive, such as epoxy or melamine thread, as long as it does not adversely affect the image.

Generally, the coating weight of the ink-receptive coating layer is 5 to 40 g/m
'', preferably 20 to 40 g/m'. If it is too low, the ink absorbency will decrease and the drying and fixing properties of the image will decrease.

Moreover, 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 explained in more detail with reference to Examples. In the examples, parts indicate parts by weight of solid content.

Example 1 Paint-1 was prepared as an aqueous solution/dispersion with a solid content concentration of 35% by weight. The main ingredients are polypropylene and inorganic pigments.
15g of solid content was placed on one side of axially and biaxially stretched multilayered synthetic paper (egg oil synthetic paper @: Yupo FPG150).
/m' and dried to obtain a recording sheet.

Paint-1 Light calcium carbonate (Albacross Fizer-MSP■: oil absorption 40.81nl/100g> 100R styrene-butadiene copolymer latex (JSRO642 Nippon Gosei Jl'mu@3) 50 parts starch (Egg Ace B Egg Cornstarch@ ) 1 part Epoxy compound crosslinking agent (Dena:+-L PC1000 Nagase Kasei @) 2 parts Example 2 Paint-2 was prepared as an aqueous solution/dispersion with a solid content of 30% by weight, and the main components were polypropylene and inorganic pigment. Axial and biaxially stretched multilayer synthetic paper (egg oil synthetic paper■;
30g/m of solid content on one side of YUPO 5GGI 10)
' and dried to obtain a recording sheet.

Paint-2 Aluminum silicate (Versilex Degussa @: oil absorption 170ml2/100g) 100i1S acrylic acid ester-styrene copolymer emulsion (Movinyl 731 Hoechst Synthesis ■) 50R polyvinyl alcohol (NLO5 Nippon Gosei @) 10 parts Example 3 Paint-3 was prepared as a toluene solution with a solid content of 20% by weight, and 30 g of the solid content was placed on one side of a synthetic paper with an I- or biaxially stretched multilayer structure (Egg Oil Synthetic Paper ■: FPG150) containing an inorganic pigment. /m' and dried to obtain a recording sheet.

Paint-3 Silica (Mizuriki Seal P363 Mizusawa Chemical ■: Oil absorption 130mJ2/100g) 100 parts Acrylic acid ester copolymer (Paraloid B82 Rohm & Haas@3) 50 parts Example 4 Paint-4 at a concentration of 30% by weight It was prepared as an aqueous solution/dispersion, coated on one side of a 50 μm polyester film (Teijin@: Tetron Film S) at a solid content of 30 g/m', and dried to obtain a recording sheet.

Paint-4 Acrylic acid ester-styrene copolymer plastic pigment (Boncourt PP200O3 Dainippon Ink Chemical ■: Oil absorption 59.8ml/100g) 100 parts Silanized polyvinyl alcohol (R2105: Kuraray ■) 50B Comparative example-1 Paint-5 was prepared as an aqueous solution/dispersion with a concentration of 35% by weight. A recording sheet was obtained by coating one side of a high-quality paper with a basis weight of 104.5 g/m' at a solid content of 30 g/m' and drying.

Paint-5 Kaolin (UW90 Engelhard: Oil absorption 46
ml/100 g) 00B Polyvinyl alcohol (NLO5 Nippon Gosei ■) 20 parts Comparative Example-2 Paint-5 was prepared as an aqueous solution/dispersion with a concentration of 35% by weight. The solid content is 2 on one side of high-quality paper of tsubo it64g/m'.
It was coated at a rate of 5 g/m' and dried to obtain a recording sheet.

Paint-5 Heavy calcium carbonate (P-10 Shiraishi Kogyo ■: vIL oil strength 26 ml/100 g) 100 parts Polyvinyl alcohol (NLO5 Nippon Gosei ■) 20 parts Comparative example-3 1- or 2-axis stretching containing inorganic pigment A synthetic paper with a multilayered structure (egg oil synthetic paper @: FPGI 50) was used as a recording sheet.

Alkylnaphthalene (KMS 113 Kureha Chemical @) 95
Using a hydrophobic dye ink in which 5 parts of an oil-soluble dye (Oil Blue 615: manufactured by Orient Kagaku Kogyo Co., Ltd.) was dissolved in 1 part,
Using a commercially available piezo type inkjet printer, the recording sheets of Examples and Comparative Examples were printed and evaluated on a five-point scale.

Image evaluation Color density was measured using the Macbeth density system.

Image clarity and dryness were evaluated visually and tactilely.

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

The water resistance of the print was determined by placing the sample in water for 30 minutes, and then visualizing and sensory evaluation of color bleeding.

The evaluation results are shown in Table 1. It was divided into five levels: ``excellent,''``good,''``average,''``poor,'' which causes problems in use, and ``unusable,'' which has serious defects.

Table 1 It makes it seem possible.

Claims (1)

[Claims] 1. On at least one side of a water-resistant sheet having an elongation in water of 0.1 or less, as a main component, a pigment having an oil absorption of 40 ml/100 g or more, which is 30% by weight or more of the solid content of the coating layer;
An inkjet recording sheet characterized in that a coating layer containing a water-insoluble adhesive in a ratio of 0.15 to 2.3 times the total amount of pigment is provided at a ratio of 5 to 40 g/m^2.