JPS58132585A - Material to be recorded - Google Patents

Abstract

PURPOSE:To provide a material with a quick ink absorption, a small dot diameter and a high dot density in which a cover layer is made of a polymer having a hydrophilic structure part and a hydrophobic structure part in such a manner to assemble numerous finely divided film pieces. CONSTITUTION:A polymer with a molecular weight of more than 2,000 having 2-40wt% of a hydrophilic structure part derived from alpha,beta-unsaturated monomer or the like and a hydrophobic structure part having affinity with dye derived from alpha,beta-ethylene-like unsaturated ester carboxylate or the like is dispersed into a solvent to make a paint. The paint thus obtained is applied on a liquid absorptive substrate 1 made of a porous material up to the quantity of 1-10g/m<2> and then, dried quickly to form a cover layer 2 in which numerous flake-like film pieces 3 finely divided by irregular crackings 4 are arranged two dimensionally in tight contact with each other. Thus, a material to be recorded is obtained as expected.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recording material (hereinafter also referred to as recording paper) used for recording characters, figures, etc. using a recording liquid.

Conventionally, recording using recording liquid, or ink, has been done using, for example, pens and fountain pens. It is widely performed using writing instruments such as felt-tip pens. Also, in recent years, a so-called inkjet recording method has appeared, and recording liquid is used here as well.

Incidentally -1 This inkjet recording method uses various ink ejection methods (for example, an electrostatic suction method, a method that applies mechanical vibration or displacement to the ink using a pressure element, a method that heats the ink and causes it to foam, and then (a method that uses the pressure of
This involves forming a shadow, and recording by attaching part or all of it to a recording material such as paper.

In this way, when recording using liquid ink, it is generally necessary that the ink does not bleed onto the surface of the recording paper and cause the print to become blurry, and that the ink is used as quickly as possible after recording. to prevent it from drying out and accidentally contaminating the paper surface, and
It is desirable that the pigment in the ink fixed on the paper does not fade.

In particular, in the inkjet recording method, (1) absorption of the recording liquid (ink) into the recording paper is fast; (2) in particular, when performing multi-color or full-color recording, there is no overlap of ink dots; Even if there is, make sure that the ink that adheres later does not disturb or flow out the dots that adhered earlier; ■ The ink droplets do not spread on the recording paper surface and the diameter of the ink dots does not become larger than necessary on the recording paper; ■ The shape of the ink dot should be close to a perfect circle, and the surrounding area should be smooth, (The density of the ink dot should be high and the area around the dot should not be blurred, (The color of the recording paper should be white, and the contrast with the ink dot should be high. (9) Dimensional fluctuations in the recording paper (e.g. wrinkles, spread)
It is necessary to satisfy various requirements such as having a small amount of data before and after recording. However, in the past, it has been understood that satisfying these demands largely depends on the characteristics of the recording paper used; There is still no recording paper that can meet the various demands. For example, in the processed paper for inkjet recording described in JP-A-52-74340, the ink can be bleached on the floor, but as soon as the diameter of the ink dots becomes large, the periphery of the dots tends to blur, and This method has the disadvantage that the size of the paper changes significantly after recording. SUMMARY OF THE INVENTION Therefore, the main purpose of the present invention is to satisfy the problems that the prior art could not solve in the technical field on paper.

In particular, it is an object of the present invention to provide a high-performance recording material (recording paper) that satisfies almost all the paper requirements for writing instruments or for recording using liquid ink using an inkjet recording method. .

Accordingly, the recording material of the present invention which achieves the above object has a coating layer formed on a substrate using a coating material containing a polymer having both a hydrophilic structural part and a hydrophobic structural part having an affinity for dyes. The coating layer is characterized in that it is made up of a large number of films finely divided by irregularly shaped cracks.

Hereinafter, the present invention will be explained in detail with reference to illustrated examples and examples.

First, the configuration of the present invention will be outlined using the schematic diagram of FIG.

In the figure, ■ is a liquid-absorbing substrate, such as paper,
Made of porous material such as cloth. 2 is coating 1-, which receives ink.

This coating layer 2 is basically composed of a film-forming resin paint, and the paint contains a hydrophilic structure part and a hydrophobic structure having affinity with dyes as main components. Contains a polymer having both moieties. Such polymers are mainly composed of heptamers (monomers) having addition-polymerizable vinyl groups.
It is a polymer in which hydrophilic structural moieties such as carboxylic acid groups, sulfonic acid groups, and sulfuric acid ester groups contain a predetermined amount of acrylic acid,
α of methacrylic acid, crotonic acid, itaconic acid, itaconic acid monoester, maleic acid, maleic acid monoester, fumaric acid, fumaric acid monoester, vinyl sulfonic acid, sulfoethyl methacrylate, sulfopropyl methacrylate, sulfonated vinylnaphthalene, etc.

β-unsaturated sonomers are used to incorporate into the polymer structure.

On the other hand, examples of the monomer unit into which a hydrophobic structural moiety having affinity with dyes is introduced include acrylonitrile,
Vinylidene chloride, non-paper α, β-ethylenically unsaturated carbo/acid ester, vinyl acetate, vinyl chloride, acrylamide, methacrylamide, hydroxyethyl methacrylate, hydroxypropyl methacrylate, glycidyl methacrylate, N-methylol acrylamide,
N-butoxymethylacrylamide and the like are most preferred.

In addition to the above monomer unit, styrene, styrene derivatives, vinylnaphthalene, vinylnaphthalene derivatives, and α,β-ethylenically unsaturated carboxylic acids 08 to C1,
aliphatic alcohol esters and the like can be used.

Incidentally, in the present invention, it is necessary to form a salt of the polymer in order to solubilize or disperse the polymer in the solvent of the paint in the form of a colloid. As partners for forming salts with the above polymer, in addition to Na, which is an alkali metal, mono-, di- or tri(methylamine), mono-,
Aliphatic amines such as G△ or tri(ethylamine), mono-
Alcohol amines such as mono-, di- or tri-(ethanolamine), mono-, di- or tri-(propanolamine), methylethanolamine, dimethylethanolamine, morpholine, N-methylmorpholine, etc.

In the above polymer, the ratio of monomer units forming the hydrophilic structural portion is particularly important.

In other words, when the weight ratio of one monomer unit serving as a hydrophilic structural moiety such as a carboxyl group, sulfonic acid group, or sulfuric acid ester group exceeds approximately 40% by weight, the so-called
The sizing effect decreases, and the extent of the recording liquid (ink) adhering to the coating layer 2 becomes excessively large, and the dye-stained area decreases, resulting in a decrease in the color density of the print.

On the other hand, if this weight ratio is less than 2 weights, the bonding force between the coating layer 2 and the substrate 1 decreases, resulting in the inconvenience that it becomes easy to peel off.

Therefore, a more preferable ratio of the parent aqueous structure moiety in the above polymer is considered to be about 25 to 40 by weight.

However, if the molecular weight of this polymer is too low, film-forming properties will deteriorate, so it is generally desirable to use a polymer with a molecular weight of about 2,000 or more.

Such polymers can be produced according to the following methods. For example, by mixing essential monomer components in a predetermined ratio, a polymer with a desired molecular weight is synthesized by a solution polymerization method, an emulsion polymerization method, a suspension polymerization method, etc. (using a polymerization regulator if necessary). do. Separately, bopolymer JfI containing acid anhydrides, esters, nitrile groups, hydroxyl groups, etc. can be prepared initially and subsequently polymerized by subsequent hydrolysis, saponification, sulfate esterification or sulfonation of these groups. A method of generating a carboxyl group or the like therein can also be adopted. The amine salt, etc. may be formed at any time; for example, any method may be used, such as polymerization using an amine salt of the carboxylic acid monomer, or adding an amine, etc. after polymerization or after the above-mentioned hydrolysis, etc. can also be adopted.

In the present invention, a coating paint is prepared by dissolving or dispersing these polymers alone or in combination in a paint solvent. At this time, if the film-forming ability of the polymer is poor, other binder resins may be used in combination. As such a resin, either a water-soluble resin or an organic solvent OT-soluble resin can be used. For example, as a water-soluble resin,
Polyvinyl alcohol, starch, casein, gum arabic, gelatin, polyacrylamide, carboxymethyl cellulose, sodium polyacrylate, sodium alginate, etc., and organic solvent-soluble resins include:
These include polyvinyl butyral, polyvinyl chloride, polyvinyl acetate, polyacrylo/tolyl, polymethyl methacrylate, polyvinyl formal, melamine resin, polyamide resin, phenol If resin, polyurethane resin, alkyd resin, and the like.

Further, as a solvent for preparing the paint, water or a mixture of water and a water-soluble organic solvent is used.

Examples of water-soluble organic solvents include methyl alcohol, ethyl alcohol, n-propyl alcohol, 1so-propyl alcohol, n-j methyl alcohol, 5ec-methyl alcohol, tert-7'f alcohol, 1s
Alcohols such as o-methyl alcohol furfuryl alcohol and tetrahydrofurfuryl alcohol; Ketone or keto alcohols such as acetone, methyl ethyl ketone and diacetone alcohol; Ethers such as tetrahydrofuran and dioxane; Esters such as ethylene carbonate and propylene carbonate; N , N-dimethylpolamide, N,N'-dimethylacetamide, N-methyl-2-pyrrolidone, jetanolamine, and other nitrogen-containing solvents.

The coating layer 2 is generally formed on the substrate 1 by a known method (for example, a roll coating method, a rod bar coating method, a spray coating method) at a rate of 1 g/lr. ~10g/W? Apply a certain amount of the paint. Also, in practical terms, 2g/rr? ~5g/-
It is best to apply a certain amount of paint.

After such a coating layer is provided, the coating layer is dried as soon as possible. The coating layer 2 thus obtained has a partial area 21! As shown in the partial enlarged view 2L, which is drawn at a magnification of about 50 times, an irregularly shaped crack 4
(Most of these cracks 4 reach the surface of the base 1.) A large number of fine scale-like coatings 3 are arranged in close contact with each other in a two-dimensional manner. The size of one scaly film 3 is not limited to %, but is approximately 10 μm×10 μm to several hundred μm×several C
Generally, the width of the crack 4 is approximately several μm, although it is not particularly limited in the present invention.

Incidentally, the individual size and shape of the scale-like film 3, the cracks 4
The width etc. can be arbitrarily changed within the range on the Y paper by adjusting or controlling the composition of the coating material or film forming conditions, especially the drying conditions after coating.

When the ink adheres to the coating layer 2 explained above,
Pigments (for example, dyes) in the ink are chemically bonded to the polymer constituting the coating 3, while solvents in the ink are quickly absorbed into the substrate 1 after passing through the cracks 4. In this way, it is good. Furthermore, since the solvent in the ink quickly migrates to the underlying substrate through the cracks, an apparent dry state can be quickly achieved on the surface of the recording paper.

Furthermore, the three scale-like films have a high dot density so that the ink dots do not become larger than necessary on the recording paper.
This is particularly effective in preventing blurring around the dots, and this is because the pigment in the ink is concentratedly adsorbed in the region of the film 3. The adsorption ability is mainly determined by the chemical properties (eg, ionicity) of the polymer.

In addition, in the present invention, there is a drawback that the area occupied by the scale-like film 3 in the coating layer 2 is extremely reduced, and, conversely, the area occupied by the cracks 4 is extremely increased.

In the latter case, the amount of ink transferred to the substrate increases, resulting in the so-called ink bleed-through phenomenon and deterioration of the dot shape. Therefore, it is desirable to avoid these aspects in the present invention.

Here, more detailed examples will be described to illustrate the effects of the present invention.

In addition, prior to Examples, synthesis examples of polymers which are the main components according to the present invention and examples of commercially available polymers are illustrated below. (・
...All the numbers in the synthesis examples are the numbers of electric switches. ) *Synthesis Example 1. 50 parts of water, 30 parts of inpropyl alcohol, 0.5 part of sodium dodecylbenzenesulfonate, and 0.5 part of ammonium persulfate are mixed in a four-piece rosette flask equipped with a stirrer and heated to 60°C. Separately, styrene 5
A mixture of 9 parts of acrylic acid, 9 parts of butyl acrylate, and 5 parts of butyl acrylate was placed in a separating funnel and gradually added dropwise over 60 minutes. After the dropwise addition was completed, the temperature was raised to 80° C. and the mixture was stirred for an additional 2 hours to carry out polymerization.

The molecular weight of the obtained polymer was about 50,000.

Example 2. In a flask similar to Example 1, 8 parts of methyl methacrylate, 5 parts of styrene, 15 parts of itaconic acid, 1 part of benzoyl peroxide, 1 part of lauryl mercaptan, 50 parts of diacetone alcohol, and 20 parts of ethylene glycol were charged, and while passing nitrogen gas Polymerization was carried out for 6 hours. The molecular weight of the obtained polymer was approximately 30,000.

A polymer was obtained from the following raw materials in the same manner as in Example 2.

(Molecular weight: approx. 15,000) (Molecular weight: approx. 20,000) (Molecular weight: approx. 30,000) (Molecular type: approx. 8,000) Commercial product example a, sodium naphthalene sulfonate formalin condensate Product name: Demol N [Kao Atlas■] b, Diisobutylene-maleic acid copolymer trade name; Demol gP [Kao Atlas■] C, Sodium polyacrylate trade name: Nopcosanto R [San Nopcosanto] d, Ammonium polyacrylate trade name; Nopcosanto RFA [San Nopco ■] e, Polysodium methacrylate trade name 1 Brimar 850 [Rohm &... -su ■] f, Styrene-maleic acid copolymer (monoester ammonium salt) Product name: 8MA resin 1440H g, PWG trade name ; Macrogol 1500 [NOF ■] h, PEG-PPG block polymer trade name; UNILUSO 40DP-50B [NOF I Kiki] Example 1 The polymer obtained in Synthesis Example 6 (100 parts of heavy duty) and water (150 (parts by weight) were sufficiently stirred and mixed to obtain a slurry.

The slurry was applied to one side of five sheets of base paper (basis weight: 60 g/m'') so that the dry solid content was approximately 4 g/rII.

Next, dry these under the conditions described in F and record paper sample.
~V was created.

*Drying conditions Sample f...Natural drying by leaving gEII...2 hours in the open (60°C) Sample 1
■...Sample for 30 minutes with hot air at 90℃■...110℃
Sample for 1 minute with hot IL of 180℃...2
The surface condition of each of the above samples was taken as an electron micrograph (X 200 ) for 1 second and is shown in FIGS. 2 to 6.

Table F-1 summarizes the results of a comparative study of the characteristics in inkjet recording of each of the samples thus obtained. In addition, in Table-1 below, dot? lIt
The measurement of x' is carried out using Sakura Microdensitometer PD.
IVI-5 (using one Konishi Roku Photo Industry Co., Ltd. tl!ri, slit width of 30μ in width, 30μ in height, sectioning speed in the X-axis direction of 10μ/crown, chart feed speed jμ', l, +++
I/! Tell! These are the results of measurement at a feed rate ratio of 1i100 times the sample to the chart.

The dot diameter is measured by measuring the diameter of the printed dot with a real g-bell.
Ta.

To determine the fixing time, place a rubber roller a certain distance away from the inkjet head used, and change the paper feed speed to change the time it takes for the ink dots to contact the rubber roller. With this device,
The time taken from the time an ink dot was generated until there was no ink spot on the roller was measured.

The ink jet recording apparatus used here had an ink ejection opening diameter (orifice diameter) of 50 μm, and the ink used had the following composition.

Ink physical properties; viscosity 3,8. cps (measured with an E-type rotational viscometer made by Tokyo Keiki) Surface tension 52.4 (line/c+++ (measured with a suspended plate surface tension meter made by Kyowa Kagaku) Table 1 (Note 1) Number of ink dots inserted (Note 2): iffff Semi-standard...Very good O...Good Δ...Badly good part), water (110 parts by weight), and ethanol (50 parts by weight) were sufficiently stirred and mixed to prepare a slurry.

This slurry was applied to the surface of a base paper with a basis weight of 65 g/- and a dry solid content of 4 g/lr? The recording paper was prepared by coating the film in such a manner as to give the following properties and drying it with hot air at 180° C. for several seconds.

When an electron micrograph was taken of the surface of this coating layer, a photograph equivalent to that shown in FIG. 6 was obtained.

Further, when inkjet recording was performed on this recording paper in the same manner as in Example 1, the results were similar to those of Sample V in Example 1.

Example 3 The polymer obtained in Synthesis Example 4 (80 parts by weight) and polyvinyl alcohol (20 parts by weight)! : After sufficiently stirring and mixing with water (150 parts by weight) to prepare a slurry, the same procedure as in Example 2 was carried out to obtain the same results as in Example 2.

Example 4.5 The same sample obtained in Example 2 was subjected to inkjet recording in the same manner as in Example 1 using the inks shown in Table 2 below. 2.
□-' □Table-2・5゛.

It should be noted that the numbers within 0 in the ink composition column indicate parts by weight, and all other numbers and symbols are based on Example 1.

Example 6 Using the same sample as in Example 3, cyan, magenta,
When full-color recording was performed using yellow and black inks, the fixing time was equivalent to that of 5, and each color was extremely clear, and a full-color photograph with a good wood-color print was reproduced. did it. ,.

Example 7 When printed on the recording paper obtained in Example 2 with a commercially available fountain pen,
There was no smearing, the ink was absorbed quickly, and I was able to write very clean letters.

As described in Section 7, in the present invention, the recording liquid (ink)
is quickly absorbed into the interior, and even if different colored recording liquids are repeatedly deposited on the same spot within a short period of time, there will be no phenomenon of recording liquid flowing out or loss of money7. It is possible to provide a recording material particularly suitable for one-color multicolor inkjet recording, which has good ink coloring properties and can suppress the spread of ink dots to an extent that does not impair the clarity of image quality.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the configuration of the present invention;
2 to 6 are diagrams showing electron micrographs of the surface of recording paper. In the figure, ■ is the base, 2 is the coating layer, 3 is the scale-like film, and 4
is a crack. Patent applicant: Canon Corporation? Figure τ Chiku 3ν Ears - 5th position

Claims (1)

[Claims] A coating layer is provided on the substrate using a coating material containing a polymer having both a hydrophilic structural part and a hydrophobic structural part that has an affinity for dyes, and this coating layer has a large number of finely divided by irregularly shaped cracks. A recording material characterized by being made of a collection of films.