JPS6325086A - Method of improving resolution of printing picture - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a high resolution discrete dot printing method and more particularly to a method for high resolution discrete dot printing and more particularly to high resolution discrete dot printing resulting from preventing lateral spread of dot printing media on a printed substrate. It concerns how to give.

With the exception of thermal and laser or photographic printing that forms images in heat- or photosensitive layers and similar printing methods that require a single medium and substrate body, printing methods do not produce droplets or small prints on a substrate. Requires deposition of medium in the form of drop-like elements. ink,
Dyes, paints, and similar media contact the printed substrate to form an image. This medium can be black or colored. The medium can be oil-based, water-based or solvent-based.

The substrate can be either a continuous film or a web of woven or non-woven fibrous material or a sheet formed from agglomerated crushed hollow spheres or flakes. The continuous film is either a polymeric film or a sheet of leather-like fabric such as vellum. The web is typically a woven or non-woven material, or a paper-like material.

The printed image can be transferred by direct contact transfer, such as in lithography, offset lithography, screen printing, electrophotography or letterpress printing; by absorption transfer, as in intaglio printing; or by electrostatic charge, for example in continuous inkjet spraying, or by inkjet spraying. Particulate media are applied to a substrate by pressure jetting an electric body, as is sometimes done, or by pressure jetting the media, as in spraying paint onto a substrate to form a billboard or large advertising image. This results from adhesion of the media by spray transfer.

In lithographic printing, the resolution of the image is limited by, among other things, the homogeneity of the substrate. When using paint in lithography, the resolution of the image is also based on the pigments and their individual particle sizes in the paint or crayon media mixture that is transferred from the lithographic stone to the printing paper.

In intaglio printing, no-ftone image resolution is based on the degree of contact screen resolution used to resolve the image into point elements. Fine gravure printing often uses 8 to 16 dots per dew, so inkjet printing aims to meet these standards.

Good inkjet engines currently in use are capable of meeting such standards.

[Problem that the invention seeks to solve]

However, in both gravure and in-jet printing, while it is possible to match the jets and separators to high resolution standards, the current limiting factor is diffusion on or into the substrate. Until now, ink diffusion has reduced the dot diameter from about 100 to 300 mm from the initial dimension of the deposited dot.
It was discovered that the size could be increased by 00 cm. Since it is easy to measure the droplet that appears from the jet on the printed page, if we compare the size of the droplet on the printing plate to the dot printed on the substrate, we find that the spread of the dot is approximately the same, i.e., the original plus 100 It turns out that it is between 300 and 300 chi. Controlling and reducing this diffusion would greatly improve the resolution of such printing methods.

Previously, the problem of ink spreading was addressed by modifying the ink, such as incorporating viscosity modifiers and fast-drying solvents into the ink. Additionally, various surfactants have been added to the ink primarily to reduce the surface tension of the ink so that the substrate is moistened and the ink will be rapidly absorbed into the paper and therefore dry quickly. However, this rapid absorption onto the substrate surface causes the ink to simultaneously spread vertically and laterally beyond an amount that may be desirable, for example to increase color density. Lateral spreading of an ink dot reduces the resolution of multiple images by enlarging the dot and thus changing the original appearance of the dot relative to its neighboring dots. This lateral expansion is known in the art as feathering and dot gain.

The current state of technology related to color inkjet printing is Bjo
Journal of Ima
gingTechnology, Volume 11, pp. 1-3 (
(1985)), where 5 to 10
Systems have been described for breaking micrometer-sized inkjet and larger droplets from larger inkjet orifices.

A method for preventing dot fusion after printing is described in U.S. Pat.
The inkjet image is described as being coated with a waterproofing composition consisting of a certain type of alum that is known to impart a waterproof coating to paper. However, this method has little value in preventing dot gain or feathering during imaging.

Other methods of controlling ink drying and absorption are described by Guen
thner and Putn4B et al., Kirk-Ot.
bmerEncyclopedia of Chemical
al Technology, 3rd edition, Volume 10, No. 897
(1980) and Vol. 16, pp. 803-825 (1980).
980) describes paper sizing agents that are added to papermaking additives and especially papermaking finishing agents. The technology includes the more recent SchwB, Rtz, US Pat. No. 4,426,466, which discloses a sizing agent that provides oil and water repellency. The sizes are either added to the finish or applied to the finished paper in an amount and medium to ensure penetration into the cellulosic substrate to which they are applied.

Additionally, U.S. Pat. No. 44 by Oshima et al.
No. 42,172 discloses an inkjet printing surface coating containing a synthetic zeolite and glass fiber blend to provide high ink absorption by zeolite particles and reduced lateral ink transfer by incorporation of glass fibers. It is written about. It will be noted that the size of the dots obtained by applying the inkjet to the resulting coated paper is in the range of .+-.27 to 5.5,- compared to that of the untreated fine paper.

Finally, in Japanese Patent Application No. 60-260376, dot f! Recording materials comprising an outer ink-absorbing layer and an inner ink-absorbing layer containing a fluorine-containing oil repellent and water have been disclosed which claim to improve the reproducibility of color tone and ink absorption capacity.

In short, prior attempts to prevent feathering and spreading of transferred ink dots have been directed to water-repellent paper sizes or coatings or water-repellent agents incorporated into the ink.

While partially effective with inks containing water as the predominant solvent, such methods have limited utility with oil-based inks or oil-based inks mixed with other organic solvents. Even with water-based inks, when used in an inkjet printer, the resulting dot size is typically about five times the diameter of the jet orifice. Because the orifice size is physically limited by the dispersion properties of the paper as well as mechanical methods, the ejection size of the droplets of prior art jets limits the practical resolution obtainable by this method.

[Means for solving problems]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a printing method using a printing paper that reduces the size of dots transferred by the printing method and maintains the reduced size of individual dots after the image is completed. Another object of the present invention is to provide an increase in the dye density of color images and an extension of the dye density life of such images by up to 200 degrees as developed by the Fademeter fade test. It is.

The above objects and benefits, among others, are achieved by the present invention which provides a method for improving the image resolution and quality of printing processes including ink droplet transfer and contact printing. The method includes the step of contacting an ink containing dyes, pigments and/or dye precursors used in such a method with a printing surface to be printed, which surface uses the ink-contacting surface as a substrate. The resulting surface tension of the coating at the interface is sufficient to cause the ink to adhere to the coated substrate and form discrete spheroids of limited contact with the coated substrate. The surface is pretreated to a certain extent by coating it with a continuous coating of a composition that makes it both oil and water repellent. Generally, the ink droplet is substantially semicircular and dries within a circumference defined by its surface tension within the reed coating substrate.

Furthermore, as a result of the present invention, the dimensions of the printed dots are
less than half that of the control (same ink from the same inkjet engine), and there is a correlation between the diameter of the ink dot and its dye density lifetime. That is, as the ink dot size decreases, the dye density lifetime increases logarithmically. The combination of reduced dot size and increased dye density provides greater print resolution in conventional ink transfer printing methods.

The present invention provides a discrete dot method comprising applying a coating consisting of a bean oil and a water repellent to the surface to be printed and contacting the printing ink with the applied surface in the form of discrete dots or droplets. The present invention relates to a method for improving images formed by printing methods. The coating composition that imparts the oil and water repellency to the coated substrate has the general formula %C, where Rf represents a fluorinated aliphatic group; Q represents at least one carbon-carbon double bond. , or a polyvalent bonding group containing at least one cyclic or non-cyclic group containing one heteroatom or a group represented by the following formula -cnB, n- (wherein n represents engineering to 20); or represents a polyvalent cycloaliphatic group or a polyvalent polycyclic aliphatic group; and
represents a dissolving or emulsifying moiety that provides at least one ionizing moiety to the molecule. ) of a fluorinated aliphatic oil and an effective amount of an ice oil surfactant or derivative.

More particularly preferably, from 1 to 3 Rf substituents are present, each being the same or different from each other.

Rf represents a monovalent or divalent substituent having at least 3 fully fluorinated carbon atoms.

The aliphatic chain can have a length of 3 to 20 carbon atoms and preferably has 6 to 16 carbon atoms.
The number of carbon atoms is most preferably 8. The backbone chains can each be a fluorinated straight chain, branched chain or aliphatic ring.

Q preferably represents a polyvalent bonding group comprising at least one carbon-carbon double bond or at least one cyclic or acyclic group containing a heteroatom.

-C6H,CL-, -C,Ct4-, heteroaromatic group,
At least one selected from the group consisting of a cycloaliphatic group and a polycyclic aliphatic group (wherein R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and n represents 1 to 20). Contains groups.

Preferred bonding groups are sulfur atom-containing groups or oxygen atoms.

X represents at least one solubilizing or emulsifying group that provides an ionizing moiety that allows the entire molecule to be soluble or emulsified in the medium used for application. The preferred application medium is water.

Solubilizing groups meeting the above conditions for water include, for example, carboxylic acids; their salts, esters and anhydrides; amic acids, urethanes; amines; amides; carbamates; soluble metal salts; quaternary ammonium salts; ammonium acid. Ammonium phosphate and carboxylate salts are preferred for use herein.

Particularly preferred X groups are ■Additionally NH4
(2) or hydroxyalkyl-substituted ammonium.

).

The above-mentioned fluorine compounds can be processed by known reactions such as hydrolysis,
They can be prepared by known methods including electrochemical fluorination reactions and telomerizations to obtain intermediates that are converted to the desired fluorine compounds by condensation or addition reactions. Suitable methods for preparing such fluorine compounds and intermediates are described in Guenthner, supra. Representative fluorinated aliphatic compounds are described, for example, in U.S. Pat.
No. 7087, No. 4419298, No. 4426666, and No. 4515640. The fixation and manufacture of these materials as described in these patents are hereby incorporated herein in their entirety.

In general, preferred compounds for application to substrates are compounds that delineate the perimeter of an ink dot on the surface of the coating while it dries or is rapidly absorbed into the coating or substrate. This gives enough surface energy to form the smallest circle. The amount of surface tension required varies with the ink itself in terms of the specific velocity of the inkjet droplets as well as the viscosity, size and ink additive content of the ink. Therefore, the nature and amount of the surfactant chosen should be such that the topmost coating when dry is repellent to both oil and water repellents, and that the liquid dots have the smallest circumference and surface area when in contact. should be ensured to form spheroids and dry quickly. Given the effect of these boundaries, the dots do not spread out laterally and can be absorbed into the coating and underlying substrate only where they come into contact.

The oil- and water-repellent-containing composition used for producing the coating agent may also contain an application medium such as water, an organic solvent or a mixture thereof, a conventional spreading agent, a pigment, a UV absorber,
It may be included along with light stabilizers, fillers, surface roughening agents, plasticizers, fillers, water repellent aids and similar additives commonly used in the manufacture of surface coatings for printing papers or films.

For inkjet printing, the coating composition per square meter is from #) 0.05 to Lo? , preferably 0.0
The oil and water repellent is applied at a rate of α005 to 0.10F and allows for the adjustment of dot density and diameter required for this invention.
It was decided that it should contain 0% by weight, preferably 0.005 to 2% by weight. Any coating method can be used to apply the coating composition to the substrate.

For the purposes of the present invention, the composition of the present invention may be applied and its drying accelerated to form a continuous film having the oil- and water-repellent surface tension amounts described above. Any substrate that can be applied as a printing surface can be used. For example, coated high-quality papers, sized or unsized as described above, are suitable for obtaining the high resolution images of the present invention. The paper can be composed of cellulosic fibers, non-cellulosic fibers or mixtures thereof. In addition to commonly used felted papers, the present invention is applicable to new printing papers made from polymer flakes as well as to recently introduced polymer films as printing surfaces. All of them are capable of applying the oil- and water-repellent surface-active compositions described above and are useful. Preferred surfaces for printing are continuous films and substrates consisting of layers of woven or non-woven, synthetic, cellulosic or polymeric fibers or particles.

Although the invention is suitable for a variety of printing methods, as described above, it is described in more detail in the specification and examples with respect to inkjet printing. That is, in inkjet printing, individual discrete inkjet droplets can be directly measured after they are ejected from the jet orifice, travel through an air gap, impinge on the printed surface, and dry on the surface. They therefore serve for further detailed study and explanation of the results of the present invention and the reasons for such results.

Inkjet printers are small tabletop devices that can reproduce the same results as large offset printers: text, pictures, and color photographs. Generally, such printing presses are referred to as ``non-impact'' because they do not use printing plates or rollers that come into contact with the printing material.

The engine of this inkjet printer actually shoots a very fine stream of ink droplets onto the paper, and that stream forms an image. Some problems that exist with this printing method are image resolution and light stability. Improvements in these image properties are a result of the present invention. Water-based inkjet inks are typically formulated with humectants to prevent evaporation and clogging of the jet boat. However, once the ink is ejected and drawn, the droplet must dry quickly. Inkjet paper manufacturers have attempted to solve this problem by formulating relatively absorbent M (consisting of PVA and silicic acid). The absorbency of paper prevents some smudging by ink; however, once an ink droplet hits the paper, the suspended droplet size also becomes several times larger. Therefore, to improve image quality, inkjet paper coatings can be incorporated with oil- and water-repellent surfactants to control the size of the ink droplets on the paper, thereby increasing the color Increasing the resolution of inkjet images is useful. This control provides various advantages, including: 1. Improved resolution of inkjet images 2. Extended dye density life λ Increased dye density [Example] A small number of drawings are shown to illustrate the present invention. Refer to and explain.

Example 1 To illustrate the present invention, a series of oil and water repellent coating additives are tested for their ability to control image forming inkjet dot density and dot diameter.

The test coating was made of unsized paper (5choeller C-15
0.19/v on paper)? (with respect to the amount of non-volatile components). ! The base for the coating composition consists of: base polyvinyl alcohol chips (molecular weight 22,000) 1
3.0IP moisturizer (Nical BX, 8% by weight) L
Make a total of 100.0 Of with deionized water.

A coating composition containing oil and water-repellent surfactant for final treatment is prepared using Suspensions A and B.

A, Additives 0.739 Deionized Water 15.00fB, Base Solution 1460f Colloidal Silica
200 are mixed with suspensions A and B and dispersed in an ultrasonic disperser. The pH is adjusted to 760 using NaOH solution. Approximately 11.4 cm of all this coating composition was applied to unsized paper.
Coat with a coating weight of about 0.1 f/- by using a 2 Meyer rod at a coating speed of cm 2 /min. The coated paper is then dried at 50° C. for 2 minutes.

Print the inkjet test image onto coated paper.

The control consisted of a similar paper composition except for the oil and water repellent. Individual dots and selected dots in the trial image are
Sweep with a microdensitometer with a slit length of 3 μm and a slit width of 0.8 μm. The chart scale is set to L99 μm per millimeter.

Table 1 shows the various oil and water repellent additives used in the coating compositions tested, the microdensities of the printed dots, and the dot diameters. Values are average values from representative sample dots obtained from microdensitometer traces.

The results reported in the table show that the coating composition of the present invention reduces the dot size to less than half that of the control.

Example 2 The samples prepared in Example 1 are exposed to a xenon fademeter for 18, 4, 39, 7, 55, 4 and 77.2 hours. The minute density values (3mm aperture) of cyan, i-zenta, yellow and black dots are recorded periodically.

Tables 2, 3 and 4 show the concentrations of the individual dyes remaining after such xenon fademeter exposure.

Table 2: Percent Black Density Remaining: Xenon Fade Meter Exposure Table 3: Percent Magenta Color Density Remaining: Table 4: Percent Cyan Color Density Remaining: From Tables 2.3 and 4, a large number of additives extend color density life. I can understand what you are doing.

Furthermore, statistical analysis shows that there is an 82-correlation between the diameter of the ink dot and its dye density lifetime. This relationship is illustrated in a drawing showing in detail the correlation in relation to the magenta color image.

This dye was chosen because it has the least photostability of the commercially available inks used in inkjet printing. This staining density when exposed to light is such that this method has been applied in many applications, for example used for gravure printing in the printing of large-scale billboard advertising sheets for outdoor public notices. , is important in the field of inkjet printing. Such advertising sheets are subjected to extreme outdoor exposure. Fademeter tests showed that over long exposure periods the expected image longevity was useful.

Therefore, the coating applied to the printing surface by the printing method of the present invention provides greater image resolution by increasing the discreteness of the individual printed dots. The dots do not embed into each other by feathering or lateral diffusion and are therefore suitable for inkjet, letterpress and gravure printing on uncoated, size or coated papers with only water or oil repellents. This prevents the muddy color stains that are often seen in . The printing method of the invention on specially coated paper beads the ink dots, thus forming small dots on the nail and delimiting the area where the dye will be absorbed. Furthermore, since the dye density lifetime of the image dots increases logarithmically with decreasing diameter of the dots (see Figure 1), the image resolution of materials printed by the method according to the invention remains even after long-term exposure to sunlight and the elements. It will last.

In summary, it will be appreciated that the present invention provides a novel method for improving images formed by discrete dot printing by applying oil and water repellents to the surface to be printed. Ru. Note that this method does not depart from the scope of the present invention as defined in the claims.
Variations in handling, proportions and ingredients may be made.

[Brief explanation of drawings]

FIG. 1 depicts a graph illustrating the relationship between inkjet droplet diameter and color stability for an embodiment of the present invention. Agent: Patent attorney Yumi Tsune (and 2 others) 1 figure/J-droplet diameter (μm)

Claims (14)

[Claims] (1) The following formula: R_f-Q-X (wherein R_f represents a fluorinated aliphatic group, Q is at least one carbon-carbon double bond, or one heteroatom or the following formula -C_nH_2_n^- (In the formula,
n represents 1 to 20. ) represents a polyvalent bonding group containing at least one cyclic or acyclic group, or a polyvalent cycloaliphatic group or a polyvalent polycyclic aliphatic group;
and X represents a dissolving or emulsifying moiety that provides at least one ionizing moiety to the molecule. ) is applied to the surface to be printed, and the printing ink is brought into contact with said coated surface in the form of discrete dots or droplets. A method for improving images formed by discrete dot printing. (2) 1 to 3 Rf substituents are present, and the Rf substituents contain at least 3 fully fluorinated carbon atoms and a straight chain, branched, or cyclic A method according to claim 1, characterized in that it represents a monovalent or divalent fluorinated aliphatic group having an aliphatic chain. (3) A method according to claim 2, characterized in that the aliphatic chain contains 8 carbon atoms. (4) Q is at least one carbon-carbon double bond or 1
A method according to claim 1, characterized in that it represents a multivalent linking group containing at least one cyclic or non-cyclic group containing 5 different atoms. (5) Q is the following formula: -O-, -S-, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, -CO-, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, -CONR'-, ▲ Mathematical formulas, There are chemical formulas, tables, etc. ▼, -▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, -S
O_2NR'-;-SO_2-, -C_nH_2_n-
, -CH=CH-, -OC_2H_4-, -C_6H_
4-, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, -C_6H_3Cl-, -C
_6Cl_4-, heterocyclic aromatic group, cycloaliphatic group and polycyclic aliphatic group (wherein R' represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and n is 1 to 20
represents. 2. A method according to claim 1, characterized in that it represents a group selected from the group consisting of: (6) Q-Represents a group selected from the following formulas -O-, -S-, ▲mathematical formulas, chemical formulas, tables, etc.▼, -SO_2NR'-, -SO_2-, and -CH=CH- The method according to claim 5, characterized in that: (7) X is derived from carboxylic acids; carboxylates, esters and anhydrides; amic acids, urethanes; amines; amides; carbamates; soluble metal salts; quaternary ammonium salts; A method according to claim 1. (8) X is the following formula: -(COO^■)_mR^m^■ or ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (In the formula, m represents 1, 2 or 3, and 0 represents 1 or 2 and R^m^■ represents a mono- or trivalent metal, or if m represents 1, R^■ also represents NH
_4^■ or hydroxyalkyl-substituted ammonium. ) The method according to claim 7, characterized in that it represents a group represented by: (9) The method according to claim 1, wherein the surfactant is present in an aqueous medium. (10) The aqueous composition contains about 0.005 to 10% by weight of a surfactant, and the composition is applied at a rate of about 0.05 to 1.0 g per square meter. A method according to claim 9. 11. The method of claim 1, wherein the surface is a substrate consisting of a continuous film and a layer of woven or non-woven synthetic, cellulosic or polymeric fibers or particles. (12) The method of claim 1, wherein the ink is water-based. (13) A method according to claim 1, wherein the ink is oil-based. (14) The above surfactant has the following formula: ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲Mathematical formulas, chemical formulas, tables, etc. There are ▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼ and C_8F_1_7-SO_2-N(C_2H_5)-C
H_2-COO^■K^■ (In the formula, R'_f is -C_6
F_1_3, -C_8F_1_7, -C_1_0F_2
_1, and R″_f is −C_8F_1_7
, -C_1_0F_2_1 and -C_1_2F_2_5
and R″′_f is −C_6F_1
_3, -C_8F_1_7, -C_1_0F_2_1 and -C_1_2F_2_5. 2. The method according to claim 1, wherein the compound is a compound selected from the group consisting of compounds represented by: