JP2000313178A - Manufacture of positively operable printing plate from novolac solution or dispersion liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain excellent ink acceptability in an image area and to improve printing durability in a non-image area by distributing a novolac resin in a predetermined pattern on a hydrophilic surface of a lithographic base, and manufacturing a lithographic printing plate. SOLUTION: The step of distributing a novolac resin in a predetermined pattern on a hydrophilic surface of a lithographic pattern is provided to manufacture the lithographic printing plate. As the novolac resin to be used, an arbitrary phenol formaldehyde resin formed by using excess phenol is used, and as preferable novolac resin, a poly(crysol-xylenol-formaldehyde) resin, a poly(phenol- xylenol-formaldehyde) resin or the like is used. The novolac resin is dispersed in an aqueous medium or dissolved in an organic solvent. In this case, a concentration of the resin in the solution is set to a range of 5 to 50 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a lithographic printing plate. Specifically, the present invention relates to a method for making a lithographic printing plate directly by using a hydrophobic novolak resin, which uses digital data from a computer, facsimile, etc., without an intermediate film having a negative or positive image. It enables the production of a lithographic printing plate directly from the output.

[0002]

BACKGROUND OF THE INVENTION In recent years, digitization of information has started from the production of printing plates for the production of printing plates, which is an upstream process of printing.
A rapid progress has been made throughout the process, whereby, for example, a photographic form system of characters by means of which a manuscript of a manuscript can easily be produced.
system or a scanner that reads the image directly. With this advancement, there has been a demand for a direct plate manufacturing method that can directly produce a lithographic printing plate from digital data output from a computer, facsimile, etc. without using an intermediate film for the production of a printing plate. .

[0003] As one example of a direct plate making method, it is known in the art to form an image or non-image portion directly on a substrate by ink-jet printing. An ink-jet printing system is a relatively quick image output system and has a simple configuration because it does not require a complex optical system. Thus, the printing system simplifies the equipment for preparing the printing plate and can reduce the cost for preparing the printing plate as the labor for maintenance is greatly reduced.

[0004] As an example of a method for making a printing plate by using an ink-jet printing system, see Japanese Patent Application Publication (KOKAI Publica).
No. 113456/1981 discloses an ink-repellent material (e.g., curable silicone).
We propose a method of making a printing plate to be printed on a printing plate by jet printing. The printing plate obtained by this method is an intaglio printing plate, and the ink-repellent material formed on the surface of the substrate serves as a non-image area. As a result, the resolution of the printed image is either shadowed areas or inverted lines (r
not very good at everdlines.
In addition, this method requires a large amount of ink because the ink-repellent material must be deposited over the entire non-image portion that occupies most of the surface of the printing plate, thereby slowing down the printing process.

[0005] US Pat. No. 5,511,477 discloses a positive or negative print on a substrate by ink-jet printing using a photopolymerizable ink composition which can optionally be preheated to a temperature of about 30 ^{° to} 260 ° C. Forming a photopolymerizable relief-type printing plate comprising forming an image; subjecting the resulting printed substrate to UV radiation, thereby curing the ink composition forming the image. Has been disclosed. This is an unpleasant process, sometimes due to the high vapor pressure and toxicity of the ink.

[0006] US Pat. No. 5,312,654 discloses an image by ink-jet printing using a photopolymerizable ink composition on a substrate having an ink-absorbing layer and a hydrophilized layer between the substrate and the absorbing layer. And exposing it to active light in the wavelength region that sensitizes the ink composition and cures the image. The printing durability of the printing plate is low.

Japanese Patent Application Publication No. 69244/1992
The method comprises the steps of: forming a printed image by ink-jet printing using a hydrophobic ink containing a photocurable component on a recording material subjected to a hydrophilic treatment; exposing the entire surface to active light. Discloses a method for producing a printing plate comprising: However, the surface of the substrate to be used for lithographic printing plates is usually subjected to various treatments such as mechanical polishing, anodizing or hydrophilic treatment to obtain good hydrophilicity and water retention. Thus, the use of ink compositions having very high surface tensions results in poor images and poor print durability on the surface of the substrate due to ink spreading.

[0008] EP-A-533 168 discloses a method for avoiding spreading of an ink by coating the lithographic base with an ink absorbing layer which is removed after printing the ink. This is an uneconomic and cumbersome method.

Research Di in May 1988
disclosure 289118 discloses a method of making a printing plate using an ink jet wherein the ink is a hydrophobic polymer latex. However, the printing plate has poor ink acceptance and low printing durability.

[0010] EP-A-776 763 deposits a liquid containing at least one reactant of a resin forming a reaction mixture on a plate using at least one printer head in a predetermined image-reproduction mode. Allowing the liquid to deposit on the plate in contact with the remaining reactants necessary to complete the mixture on the surface of the plate; resin-polymerizing the complete mixture on the plate Disclosed is a method of making a lithographic printing plate containing a printable resinous image, comprising polymerizing under conditions to produce a lithographic printing plate containing a resinous image printable thereby. This is a cumbersome method for making a printing plate by ink jet.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an excellent lithographic printing plate having excellent ink receptivity in image areas and no ink receptivity in non-image areas and having high printing durability. It is an object of the present invention to provide a method for making a lithographic printing plate from a lithographic base having a hydrophilic surface image-wise imaged with a polymer.

Yet another object of the present invention is to provide a method for making a lithographic printing plate in a rapid, economical and ecological manner without using a lithographic base wet development.

Further objects of the present invention will become clear from the description hereinafter.

[0014]

SUMMARY OF THE INVENTION In accordance with the present invention, there is provided a method of making a lithographic printing plate comprising the step of distributing a novolak resin in a predetermined pattern on a hydrophilic surface of a lithographic base.

[0015]

DETAILED DESCRIPTION OF THE INVENTION Novolak is any phenol-formaldehyde resin made with excess phenol in the reaction. The phenol can be phenol, cresol, and the like. Preferred novolak resins are poly (cresol-xylenol-formaldehyde) resins and poly (phenol-xylenol-formaldehyde) resins. Novolak resins are dispersed in an aqueous medium or dissolved in an organic solvent. Suitable organic solvents are, for example, 1-methoxy-2-propanol, ethyl acetate, methyl ethyl ketone and isopropanol. The concentration of the resin in the solution is in the range of 5 to 50% by weight, more preferably 10 to 30% by weight. The concentration of the novolak resin in the aqueous dispersion ranges from 5% by weight to 80% by weight, more preferably from 20 to 60% by weight. The novolak resin according to the present invention has at least 1000, more preferably at least 5000, most preferably at least 100
It has a molecular weight of 00. The novolak may contain an epoxy group.

Novolak resins are hydrophobic, lipophilic resins. In the present invention, the hydrophobic lipophilic compound is a compound which is wetted by oil when placed in a mixture of water and oil, whereas the hydrophilic compound is wetted by water when placed in a mixture of water and oil.

According to the present invention, the lithographic base having a hydrophilic surface is preferably sprayed with droplets of the hydrophobic polymer in a predetermined pattern on the hydrophilic surface.
Preferably the heating is at a temperature of at least 45 ° C, more preferably at least 55 ° C.

In one embodiment, the heating is performed in an oven. In that case, the lithographic base having a hydrophilic surface is heated for preferably at least 1 minute, more preferably at least 5 minutes, after spraying the hydrophobic polymer droplets in a predetermined pattern.

In another embodiment, a hot body (hot body) is used.
The heating is carried out by contacting y).

In another embodiment, the heating is performed using an IR-heater or a laser. In that case, the heating time is the laser residence time, that is, the time of 0.005 to 2 μsec. This mode of heating requires that the lithographic base or novolak resin solution or dispersion contains a compound capable of converting laser light to heat.

It is particularly preferred to use infrared pigments or dyes for that purpose. Particularly desirable in the present invention are infrared dyes. However, for example, carbon black, conductive polymer particles, metal carbides, borides,
Pigments such as nitrides, carbonitrides, bronze-structured oxides and oxides structurally related to the bronze family but without the A component, for example WO _2.9 , can likewise be used.

Curing agents can be added to the solution or more preferably the dispersion of the novolak resin to improve abrasion resistance.
Suitable curing agents are Texaco Chemical Co.
Jeffamine ^™ and Witco
Euredu, a trade name of Chemical Cob
Amines such as rTB03345 ^™ , but mercaptan or alcohol containing components can also be used. The hardener is preferably used in an amount of 5 to 80% by weight of the novolak.

According to the present invention, coupling agents can be added to the novolak solution or dispersion to improve the adhesion between the novolak and the hydrophilic surface of the lithographic support. Suitable coupling agents are alkoxysilanes with amino- or epoxy functionality, but those with other adhesion-enhancing functionality are also possible. The coupling agent is preferably used in an amount of 2 to 10% by weight.

According to the present invention, the lithographic base can be an anodized aluminum support. A particularly preferred lithographic base is an electrochemically polished and anodized aluminum support. The anodized aluminum support can be treated to increase its surface hydrophilicity. For example, if an aluminum support is
Silicification can be achieved by treating the surface with a sodium silicate solution at an elevated temperature such as ° C. In another case, phosphating can be applied,
It involves treating the aluminum oxide surface with a phosphate solution, which may further contain inorganic fluoride. Additionally, the aluminum oxide surface can be rinsed with a citric acid or citrate solution. This treatment can be performed at room temperature or about 30-50 ° C
Can be performed at slightly elevated temperatures. A further interesting treatment involves rinsing the aluminum oxide surface with a bicarbonate solution. Furthermore, the surface of the aluminum oxide is polyvinyl phosphonic acid, polyvinyl methyl phosphonic acid,
The treatment can be carried out using polyvinyl alcohol phosphate, polyvinyl sulfonic acid, polyvinyl benzene sulfonic acid, polyvinyl alcohol sulfate and sulfonated aliphatic aldehyde, and acetal of polyvinyl alcohol. It is further apparent that one or more of these post-treatments can be performed alone or in combination. A more detailed description of these processes can be found in GB-A-1 084 07
0, DE-A-4 423 140, DE-A-4 4
17 907, EP-A-659 909, EP-A-
537 633, DE-A-4 001 466, EP
-A-292 801, EP-A-291 760 and U.S. Pat. No. 4,458,005.

According to another mode in connection with the present invention, a lithographic base having a hydrophilic surface comprises a flexible support, for example a paper or plastic film provided with a cross-linked hydrophilic layer. Particularly suitable crosslinked hydrophilic layers are
It can be obtained from a hydrophilic binder cross-linked using a cross-linking agent such as formaldehyde, glyoxal, polyisocyanate or hydrolyzed tetra-alkyl orthosilicate. The latter is particularly preferred.

Examples of hydrophilic binders include hydrophilic (co) polymers such as vinyl alcohol, acrylamide, methylolacrylamide, methylolmethacrylamide, acrylate acid, methacrylate acid,
Homopolymers and copolymers of hydroxyethyl acrylate and hydroxyethyl methacrylate or maleic anhydride / vinyl methyl ether copolymer can be used. The hydrophilicity of the (co) polymer or (co) polymer mixture used is preferably the same or higher than that of the polyvinyl acetate hydrolyzed to at least 60% by weight, preferably to the extent of 80% by weight.

The amount of crosslinking agent, especially tetraalkyl orthosilicate, is preferably at least 0.2 parts by weight, more preferably 0.5-5 parts by weight, most preferably 1.0 parts by weight per part by weight of hydrophilic binder. Parts by weight to 3 parts by weight.

The lithographic base crosslinked hydrophilic layer used in accordance with this embodiment preferably also contains substances that enhance the mechanical strength and porosity of the layer. Colloidal silica can be used for this purpose. The colloidal silica used can be in the form of any commercially available water-dispersion of colloidal silica having, for example, an average particle size of at most 40 nm, for example 20 nm. In addition, inert particles of a larger size than colloidal silica, for example J.I. C
olloid and InterfaceSci. ,
Vol. 26, 1968, pages 62 to 6
At least 100 particles of silica or alumina or particles of titanium dioxide or other heavy metal oxide prepared according to StOEber as described in paragraph 9.
Particles having an average diameter of nm can be added. The introduction of these particles gives the surface of the cross-linked hydrophilic layer a uniform rough texture consisting of microscopic hills and valleys, which serves as a reservoir for water in the background areas.

The thickness of the lithographic base crosslinked hydrophilic layer according to this embodiment can vary within the range of 0.2 to 25 μm, preferably 1 to 10 μm.

A specific example of a cross-linked hydrophilic layer suitable for use in accordance with the present invention is described in EP-A-601 24
0, GB-P-1 419 512, FR-P-23
00354, US-P-3 971 660, US-P
-4 284 705 and EP-A 514 490.

As the lithographic base flexible support relating to the present embodiment, it is particularly preferable to use a plastic film, for example, a polyethylene terephthalate film, a polyethylene naphthalate film, a cellulose acetate film, a polystyrene film, a polycarbonate film and the like. preferable. The plastic film support can be opaque or transparent. Glasses having a thickness of less than 1.2 mm and a breaking stress (under tensile stress) equal to or higher than 5 × 10 ⁷ are also suitable as flexible supports.

It is particularly preferable to use a polyester film support provided with an adhesion promoting layer. Particularly suitable adhesion promoting layers for use in accordance with the present invention are EP-A-619.
524, EP-A-620 502 and EP-A-6
Comprising a hydrophilic binder and colloidal silica as disclosed in US Pat. Preferably the amount of silica in the adhesion improving layer is between ^{200mg / m 2 ~750mg / m 2} . Furthermore, the ratio of silica to hydrophilic binder is preferably more than 1 and the surface area of the colloidal silica is preferably at least 300 meters ² / g, more preferably at least 50
0 m ² / g.

A novolak dispersion is defined as a stable colloidal dispersion of a novolak substance in an aqueous medium. Novolak particles are usually roughly spherical, of typical colloidal size, and have a particle size of about 20-1000.
nm range. The dispersion medium is usually a dilute aqueous solution containing substances such as electrolytes, surfactants, hydrophilic polymers and initiator residues.

To facilitate evaluation of the resulting lithographic printing plate, a colored hydrophobic novolak resin can be used. For example, carbon black or a dye or pigment can be mixed with the novolak resin.

Preferably, the novolak resin can be distributed on a lithographic base having a hydrophilic surface by an ink jet printer.

In order to prevent evaporation of the liquid in the ink-jet nozzle and to prevent clogging due to precipitation of dissolved or dispersed components, a volatilization inhibitor is added to the ink according to the invention, if necessary.

Blowing from the ink jet nozzle (blo
wing) A surfactant is preferably added to the ink according to the present invention in order to adjust the size of the droplets of the dispersion, to adjust the surface tension of the ink so that images can be formed with high resolution.

Other components can be added to the inks used in accordance with the present invention, if desired. For example, thermal polymerization inhibitors, infection inhibitors (desinfecta)
nts), anti-staining agents and anti-fungal agents can also be added. The use of buffers and solubilizers is effective for improving the solubility or dispersibility of the polymer. In order to suppress the foaming of ink in the ink-jet nozzle,
Addition of defoamers and defoamers is also possible.

Optionally, other components which enhance the quality of the dispersion can be added.

The following steps are required for image formation. If necessary, hydrophobic dots of hydrophobic novolak resin are sprayed onto the lithographic base in a predetermined pattern as the plate passes through a printer or by a print head reciprocating on the plate. According to one aspect of the present invention, the microdot has a diameter of about 30 μm. In a subsequent step, the lithographic base on which the hydrophobic novolak resin has been sprayed can be heated. This can be done by irradiation, for example by convection in an oven or by contact with a hot surface, by flash exposure, by an IR-heater or by laser irradiation.

Image formation can also be performed using a lithographic base already on the printing cylinder. In that case, optional heating of the novolak resin can be performed by using a heated printing cylinder.

The printing plate of the present invention can be used as a seamless sleeve printing plate in a printing process. This cylindrical printing plate has a diameter such that it can be slid on the printing cylinder. Further details on sleeves can be found in "GrafischNieuws" ed. Ke
esing, 15, 1995, page 4 to 6.

The following examples illustrate the invention without limiting it. All parts and percentages are by weight unless otherwise indicated.

[0044]

EXAMPLES Example 1 Preparation of Novolak Solutions Seven solutions were prepared: Solution 1: 15% modified high molecular weight phenolic resin in methyl ethyl ketone (Albertol KP 648).
^TM- Chemische werke Albert
t). -Solution 2: 10% modified high molecular weight phenolic resin in ethyl acetate (Id.). -Solution 3: 10% modified phenolic resin in methyl ethyl ketone. (Krumhaar K4733 ^TM -L
solution—solution 4: 10% phenolic resin in methyl ethyl ketone. (Durez 28391 ^TM -Occident
al Chemical) -Solution 5: Alnovol ^™ 6 in isopropanol
%solution. Alnovol is Clariant, Germ
Any trade name for cresol formaldehyde resin from Any. Solution 6: Alnovol ^™ 1 in isopropanol
4% solution. Solution 7: Alnovol ^™ 1 in isopropanol
0% solution. In this embodiment, P.I. E. FIG. T. The solution was sprayed onto the hardened polyvinyl alcohol on the plate using HP690C. 2500 copies were printed from each of these plates.

Preparation of a layer of hardened polyvinyl alcohol on polyethylene terephthalate Preparation of a solution for the subbing layer 31.7 ml (11.1 g) in a solution of 11.4 g gelatin (viscosity: 19-21 mPas) in 940 ml water. 4g
Was added KIESELSOL 300F of solid product) (surface area of the product name -g per 300 meters ² about 30% aqueous dispersion of colloidal silica). Anionic wetting agent (0.6 g) and biocide (1 g) were added.

Preparation of hydrophilic layer 21.5% TiO ₂ (average particle size 0.3-0.5 μm)
And 440 g of a dispersion containing 2.5% polyvinyl alcohol in deionized water, continuously stirring, 250 g of a 5% solution of polyvinyl alcohol in water, 22% emulsion of hydrolyzed tetramethyl orthosilicate in water Was added and 22 g of a 10% solution of the wetting agent were added. Then 183 g of deionized water was added to the mixture and the pH was adjusted to pH = 4.

Preparation of hydrophilic support 170 mg / m ² of copoly (vinylidene chloride / methyl methacrylate / itaconic acid) latex and 100 m
A polyethylene terephthalate support primer-coated with silica of 40 mg / m ² having a surface area of ² / g, a solution for the above undercoating layer 75
It was applied at a solids coverage of 0 mg / m ² . On top of the subbing layer is coated the above hydrophilic layer to a wet coating thickness of 50 g / m ² and dried at 30 ° C.
The film was hardened by subjecting it to a temperature of 0 ° C. for one week.

Table 1 shows the results.

[0049]

[Table 1]

-Ink acceptability:--None-Very low density + Correct after 10 copies ++ Correct after 3-5 copies ++ Suitable after + +1 copies-Abrasion resistance-2500 Obvious wear after copying + slight wear after 2500 copies + very little wear after 2500 copies + no wear after 2500 copies.

As can be seen, all solutions gave good to excellent print results.

Example 2 Two dispersions of novolak resin were prepared: Dispersion 1: Shell C per 100 ml of water
100 g of Epi-Rez 5003-W-55 ^™ , a trade name for o-bisphenol-A novolak, and 17.8 g of Euredur TB 03J, an amine curing agent from Witco Chemical Co.
544 ^™ . Dispersion 2: Shell C per 100 ml of water
100 g of Epi-Rez 5003-W-55 ^™ , a trade name for o-bisphenol-A novolak, and 88.8 g of Euredur ^™ , an amine curing agent from Witco Chemical Co. These dispersions were jetted imagewise onto a hydrophilic support, which was a layer of hardened polyvinyl alcohol on anodized aluminum or polyethylene terephthalate. Anodized aluminum was prepared as follows: Preparation of anodized aluminum support Aluminum foil 0.30 mm thick was foiled at 50 ° C. in an aqueous solution containing 5 g / l sodium hydroxide. Submerged and degreased by rinsing with deionized water. Then 3
Using alternating current at a temperature of 5 ° C. and a current density of 1200 A / m ² , 4 g / l hydrochloric acid, 4 g / l boric acid and 5 g / l
The foil was electrochemically polished in an aqueous solution containing 1 aluminum ion to form a surface topology with an average centerline roughness Ra of 0.5 μm.

After rinsing with deionized water, then 300 g /
at 60 ° C. using an aqueous solution containing 1
The aluminum foil was etched for 0 seconds and rinsed with deionized water at 25 ° C. for 30 seconds.

The foil was then placed in an aqueous solution containing 200 g / l of sulfuric acid at a temperature of 45 ° C., a voltage of about 10 V and 150
Anodize at a current density of A / m ² for about 300 seconds to form an anodized film of 3.00 g / m ² Al ₂ O ₃ , then wash with deionized water and contain polyvinylphosphonic acid Work-up with the solution and subsequently with the solution containing aluminum trichloride, and with deionized water
Rinse at 0 ° C. for 120 seconds and dry.

On each of these supports, two samples were imaged using Dispersion Compositions 1-2 and one was allowed to stand for 30 minutes and then AB-Dick 36
The printing was performed using a conventional ink (Van Son rubber base) and a commercially available dampening solution (2% Name) applied on a printing press. Another sample was placed in an oven at 60 ° C for 2 hours.
It was heated for 5 minutes and then cooled to room temperature for 5 minutes before use as a printing plate. Table 2 shows the printing results.

[0056]

[Table 2]

The ink receptivity and abrasion resistance are defined as shown in Example 1. -Support: Alu (anodized aluminum) or PTT (polyvinyl alcohol hardened layer) All samples gave good ink receptivity and samples coated on aluminum or PTT are acceptable after heating It can be seen from the wear resistance that good wear resistance was given.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Augustine Meisters Belgium 2640 Malt Cell Septes Trat 27 Agfa-Gevuert na Mrose Fennoutjapp (72) Inventor Hoop van Aelt Belgium Bee 2640 Maltcell Septes Trat 27 in Agfa-Gevert na Mrose-Fennoutjap (72) Inventor Riyuk Laenders Belgium Inside

Claims (9)

[Claims] 1. A method for preparing a lithographic printing plate comprising the step of distributing a novolak resin in a predetermined pattern on a hydrophilic surface of a lithographic base. 2. The method according to claim 1, wherein the novolak resin is poly- [cresol-xylenol-formaldehyde} resin or poly- [cresol-xylenol-formaldehyde] resin.
[The lithographic printing plate production method according to claim 1, wherein the phenol-xylenol-formaldehyde resin is used. 3. The method according to claim 1, wherein the novolak is dissolved in an organic solvent. 4. The method according to claim 3, wherein the concentration of the resin in the solution ranges from 5 to 50% by weight. 5. The method according to claim 1, wherein the novolak is dispersed in an aqueous medium. 6. The resin concentration in the dispersion is 5 to 80% by weight.
6. The method of claim 5, wherein 7. The method according to claim 1, wherein the novolak comprises a curing agent. 8. The method according to claim 1, wherein said novolak comprises a coupling agent. 9. The method according to claim 1, wherein the dispensing step is performed by an ink jet device.