JPS58134165A - Waterless lithography ink curable by ultraviolet light - Google Patents

Abstract

PURPOSE:The titled ink washable without using a polar solvent, being slightly stained, comprising varnish obtained by blending a specific thermoplastic resin soluble in aliphatic hydrocarbon-based solvents with an acrylic prepolymer, etc., water repellent silicone, a thickening agent, etc. in a specific ratio. CONSTITUTION:20-80wt% varnish obtained by blending 100pts.wt. thermoplastic resin having 50-180 deg.Csoftening point, soluble in aliphatic hydrocarbon- based solvents, comprosing a homopolymer and/copolymer of 8-10C aromatic vinyl compound (e.g., styrene, etc.) and/or 10C alicyclic vinyl compound (e.g., dicyclopentadiene, etc.), and/or a copolymer of it with an aliphatic vinyl compound (e.g., 1-butene, etc.) with 20-1,000pts.wt. (meth)acrylic prepolymer containing one or more (meth)acryloyl groups in the molecule is mixed with 0.1-10wt% water repellent silicone (e.g., dimethyl silicone oil), 0.5-10wt% thickening agent, 5-50wt% pigment, and 1-20wt% photoreaction initiator, to give the desired ink.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a waterless lithographic printing ink that is cured by ultraviolet rays and does not damage a cleaning liquid-covered printing plate after printing.

Lithographic printing generally consists of a hydrophilic area that is easily wetted by water (hereinafter referred to as non-image area 0) and a water-repellent area that repels water (hereinafter referred to as image area 4). Printing has been carried out by moistening the line area with dampening water or a dampening liquid (hereinafter referred to as water) to magnify the difference in field chemical properties between the non-print area and the print area. However, this follow-up method cannot prevent water from getting into the ink, and various problems occur due to the presence of water in the ink. -The printing process will be carried out□
It's starting to get worse. This water-free lithographic printing plate has a photosensitive resin layer provided on an aluminum substrate, and a silicone layer with low ink receptivity is further formed in the non-image area on top of the photosensitive resin layer. This photosensitive resin is, for example, a mixture of orthonaphthoquinonediazide and a novolac resin, a mixture of an aromatic bisazide compound and a resin having a carbon-carbon double bond, an I-boly cinnamic acid vinyl ester resin, or a diazo resin. It is insoluble in aliphatic hydrocarbons (kerosene, etc.), but has the property of being easily soluble in other polar solvents, such as ketones, esters, cellosolves, etc.

On the other hand, as printing speeds have increased, ultraviolet curable inks have come into widespread use, but the vehicle is generally an esterified product of polyhydric alcohol and acrylic acid.
Esterified products of hydroxyl-terminated polyester polyol and acrylic acid, esterified products of polyether polyol and acrylic acid, esterified products of epoxy resin and acrylic acid, reaction products of hydro-, xyalkyl acrylate and raw polyincyanate, etc. It is a petroleum-based (aliphatic hydrocarbon-based) solvent that has been widely used as a solvent for lithographic printing inks because it has almost no solubility in non-polar solvents such as hydrocarbon-based solvents. However, the ink on the printing press could only be washed with polar solvents such as ketones, esters, and cellosolves after printing was completed.

In other words, when using ultraviolet curable ink, it was necessary to replace all rubber rolls, printing plates, etc. of the printing press with ones that could withstand polar solvents. However, it is difficult to obtain a water-free lithographic printing plate containing silicone rubber as described above that will not be altered or deformed by polar solvents, so it is difficult to perform ultraviolet curing printing with a water-free lithographic printing plate. Furthermore, in waterless planographic printing, not only the ink receptivity on the printing plate varies, but also the ink has special physical properties, tackiness, and tackiness that is too strong or too weak.

Furthermore, unless the ink has a certain degree of cohesive force and thixotropy, it cannot withstand practical use. Therefore, phase components such as water and polyhydric alcohols are added to the ink to form an emulsion. A method has been proposed in which the ink is mixed in the form of ink, but this method has the drawback that it tends to cause poor ink transfer or background smearing.

Next, ink containing a silicone component became known. Is this shinki? Are you saying that attached energy can be controlled? It is excellent in that respect.

However, what type of viscoelastic ink can be used?1. This was never the case, and it was impossible to use inks that had a high cohesive force, thixotropy, or tack and were easily smeared if rubbed. In particular, since UV-curable inks contain a considerable amount of prepolymer components, only low viscoelasticity can be obtained, so simply adding silicone to these inks will cause the ink to adhere to the Japanese printing lines, resulting in so-called smearing. This makes it more likely to occur.

However, as pointed out by the inventors, is it possible to clean without using a polar solvent? The present invention was developed as a result of various studies aimed at solving the drawbacks of the prior art, which is characterized by the use of silicone or silicone alone.

That is, the present invention provides a homopolymer and/or copolymer of an aromatic vinyl compound having 8 to 10 carbon atoms and/or an alicyclic vinyl compound having 10 carbon atoms, and/or a part or At least 1 per molecule per 100 parts by weight of thermoplastic camphor resin, which is composed of a copolymer of all resins and an aliphatic vinyl compound, and has a softening point of 50 to 180C and is soluble in aliphatic hydrocarbon water and thread solvent. (meth)acryloy/L: having a group (
A varnish containing 20 to 1,000 parts by weight of meth)acrylic prepolymer is mixed with 20 to 80 parts by weight, a water-repellent silicone (Bl is 0.1 to 10 parts by weight), and a thickener (q is 0.
A water-free lithographic printing ink that is cured by ultraviolet rays and contains 57-10% by weight of pigment 0, 5-50% by weight of pigment 0, and 1-20% by weight of photoreaction initiator (I). , is provided.

Examples of aromatic vinyl compounds having 8 to 10 carbon atoms used in the present invention include styrene, 2-methyl-, x-butene, 2-methyl-2-butene, methylstyrene, vinyltoluene, indene, methyl Examples include indene, riwsry, and impropenyltoluene.

In addition, examples of alicyclic vinyl compounds having 10 carbon atoms include dicyclopentadiene, α-pinene, β-pinene, etc.
Examples of aliphatic vinyl compounds include 1-butene and 2-butene.
Butene, 1,3-butadiene, l-pentene, 2-hentene, cyclopentene, 1,3-hyherylene, imprene, cyclobentasie/, 2-methyl-1-butene, 2
-Methyl-2-butene, etc.0 The present invention uses one or more of these various compounds to
For example, homopolymerization or copolymerization is carried out by a known method using a free delta two-foot type catalyst.

Alternatively, an aliphatic hydrocarbon solvent-soluble thermoplastic resin having a softening point of 50 to 180 C and a mixture of these homopolymers or copolymers can be used. In addition, f' Water other than the above, within a range that does not impair the effects of the invention.
It is also possible to use a resin obtained by copolymerizing a vinyl monomer having a group, a carboxyl group, a 1 (ester group, etc.).

Another constituent of the printing ink composition according to the invention (
The meth)acrylic prepolymer CB) having one or more (meth)acryloyl groups in one molecule can be used.

However, mono- and poly(meth)acrylates are not necessarily produced as a single compound, but are often produced as a mixture of various compounds.
For the ratio of meth)acryloyl groups, molecular weight, etc., values calculated as average values based on theoretically assumed compounds may be used.

The ratio of the prepolymer to the monomer to be used is determined by the viscosity and degree of the resin solution after dissolving the thermoplastic resin, which is another component of the present invention.

(Meth)acrylic prepolymers are preferably liquid at room temperature, and include liquids obtained by dissolving highly viscous prepolymers with monomers. The molecular weight per (meth)acryloyl group must be 100 or less, preferably 600 or less, in view of the curing rate.

Examples of (meth)acrylic prepolymers that can be used in the present invention include mono- and poly(at) aliphatic, alicyclic, and araliphatic di- to hexavalent polyhydric alcohols and polyalkylene glycols.
meth) acrylates, such as t-ba, ethylene glycol, propylene gelicol, etc.; mono- and poly(meth)acrylates of polyhydric alcohols in the form of adducts, such as bisphenol A dioxyenal ether.

lci Mono- and poly(meth)acryloyloxyalkyl phosphate esters 0゛(d) Polyester mono- and poly(meth)acrylates.

tel epoxy mono and poly(meth)acrylates.

ge) polyurethane mono and poly(meth)acrylates.

(gl polyamide mono and poly(meth)acrylate.

(h) Polysiloxane mono and poly(meth)acrylate.

Modified mono- and poly(meth)acrylates described in fil, fa) to fhl, These oligoester (meth)acrylates may be used alone or in combination of two or more, or if necessary, other (meth)acrylates may be used. ) It is also possible to add and use acrylate monomers and polymers.

Thermoplastic resin according to the invention - 100 parts by weight
Stone (meth)acrylic prepolymer having at least 4) one (meth)acryloyl group in the molecule is 20 to 1000
Using parts by weight is effective.

If it is less than 20 parts by weight, there is a lack of components that react and cure with ultraviolet rays, making it impossible to obtain a tough film.
If the amount is more than 0 parts by weight, cleaning with a hydrocarbon solvent becomes difficult, which is not preferable.

Fes (5) thus obtained 20-80% by weight
In contrast, examples of water-repellent silicone include dimethyl silicone oil, methylphenyl silicone oil, alcohol-modified silicone oil, fat-11i silicone oil, α-methylstyrene-modified silicone oil,
Amine-modified silicone oil and the like can be used, but the present invention is not limited to these, and other silicones can also be used as long as they are liquid at room temperature and are compatible with the festival material used in the present invention.

The amount of water repellent silicone added is 0.1 to 10% by weight, more preferably 0.5 to 5% by weight. If it is less than 0.1% by weight, ink removal in non-image areas will be insufficient and stains will easily occur on printed matter.
Moreover, if it is added in an amount exceeding 10% by weight, poor ink transfer between rotors and poor ink transfer to image areas are likely to occur. However, as mentioned above, adding only the water-repellent silicone (5) does not provide any practical effect, so the addition of the thickener (Q) is essential in the present invention.

Thickeners used in the present invention (CL include white carbon such as magnesium silicate, anhydrous silicic acid, hydrosilicic acid, aluminum silicate, calcium silicate, etc., aminated bentonite, ultrafine particle silica, etc.) Raised article.

In the present invention, it is important to use the above-mentioned water-repellent silicone (Bl) and thickener (q) in combination; the effect of the present invention cannot be obtained with either one alone; For the first time, without reducing the ink transfer rate,
Moreover, they discovered that it is resistant to staining and can produce clear prints, which is an unexpected effect.

The type and amount of thickener (q) are determined by the viscosity of the fest and the type and amount of pigment □. 2
．． α・6. ,,□21. . 7□. , 5 □ If you don't, the □ viscosity of the ink will become too low and stains will occur on the plate surface.
If the amount is more than 10% by weight, the fluidity of the ink will be poor, the so-called bulge phenomenon will occur, and the ink will not be supplied uniformly, resulting in poor halftone dot reproducibility.

Pigments I include various types conventionally used for printing inks, such as inorganic pigments such as carbon black, organic pigments such as Carmine 6B, Watching Red, Phthalocyanine Blue, and Penji/Yellow, and complementary colors. Dye lakes such as malachite green, rhodamine, and methyl violet can also be used.

The amount used varies depending on the hue, but it may be used within the range of 5 to 50% by weight.

The photoinitiator (g) is benzifenone, chlorobenzophenone, benzoin, benzoin alkyl ether, benzylacetophenone, chloracetophenone, methyl orthobenzoylbenzoate, jetoxyacetophenone, α-hydroxyisobutyrophenone, chloranthraquinone methylthioxanthone, para- Examples include, but are not limited to, dimethylaminobenzal, dehyde, and the like.

The photoreaction initiator) may be added in an amount of 1 to 20% by weight; if it is too small, the curing speed due to ultraviolet irradiation will be slow, and
If the amount is too large, the physical properties of the cured film will deteriorate, so it is not appropriate for the adhesive. 7. The Fes particles in the water-free lithographic printing ink that is cured by ultraviolet light according to the present invention are soluble in aliphatic hydrocarbon solvents such as kerosene, which are conventionally used for cleaning printing presses.
Even if insoluble (meth)acrylic prepolymers are mixed in these solvents, the ink as a whole system will eventually become soluble in aliphatic hydrocarbon solvents, making it possible to use various known radiation-curable inks. Since it is now possible to wash without the use of polar solvents such as ketones, esters, and cellosolves, which were indispensable in the past, various waterless lithographic printing plates can be used as is.

In addition, the combination of water-repellent silicone Q31 and thickener (Q) makes it easy to optimize the ink's adhesive strength, ink's cohesive force, viscoelasticity, etc., and does not cause stains even for a long time. Now you can get beautiful prints.

Next, the present invention will be explained in more detail by comparison with Examples and Reference Examples, but is not limited thereto.

In addition, in these examples, all parts or % indicate parts by weight or % by weight.

Example 1 Aromatic thermoplastic petroleum resin (Nippon Petrochemical Company, trade name Neopolymer S) 4'011S made by polymerizing an aromatic vinyl compound having 8 to 10 carbon atoms to have a softening point of 90G, and 1,
90 to 100 parts of 6-hexanediol acrylate and 50 parts of trimethylolpropane triacrylate
Resin composition A was obtained by heating and dissolving in C and then mixing.

This resin composition A was milled in a three-roll mill with the following formulation to prepare an ultraviolet curable printing ink.

Resin Composition A7 Partial Sensitizer (Hensephenone/Michler Nuketone = 1/1)
8 parts Ultrafine particle silica 5 parts Phthalocyanine blue 15 parts Example 2 80 parts of an aromatic vinyl compound having 8 to 10 carbon atoms and 20 parts of an aliphatic vinyl 75 compound having 4 to 5 carbon atoms were used as a Friedel Krach type catalyst. A resin composition B was prepared in the same manner as in Example 1, except that a thermoplastic petroleum resin having a softening point of 100 C obtained by copolymerization was used, and a printing ink was also prepared in the same manner as in Example 1.

Example 3 A dicyclopentadiene thermoplastic resin containing an ester group in the molecule and having a softening point of 10 Or, which is an alicyclic vinyl compound having 10 carbon atoms (Nippon Zeon Co., Ltd., trade name, Queenton 1500) A resin composition "C" was prepared in the same manner as in Example 1, except that the same method as in Example 1 was used, and a printing ink was also prepared in the same manner as in Example 1.

Example 4 80 parts of an aromatic vinyl compound having 8 to 10 carbon atoms and 20 parts of dicyclopentadiene were copolymerized to have a softening point of 100.
A resin composition was prepared in the same manner as in Example 1, except that a thermoplastic petroleum resin designated as C was used, and a printing ink was also prepared in the same manner as in Example 1.

Example 5 and 20 parts of an aliphatic vinyl compound having 4 to 5 carbon atoms.

60 parts of dicyclobenkuzief, 20 parts of butyl acrylate
A resin composition E was prepared in the same manner as in Example 1, except that a thermoplastic resin with a softening point of 100 C obtained by copolymerizing with .

Reference Examples 1 to 3 Using the resin composition A of Example 1, the formulations shown in Table 1 were kneaded in a three-roll mill to create printing inks, which were used as Reference Example 1, Reference Example 2, and Reference Example 3, respectively. did.

Reference Example 4 Example 1 except that a thermoplastic resin having a softening point of 150C is used by copolymerizing styrene and maleic acid at a molar ratio of 1:1.
A resin composition F was prepared in the same manner as in Example 1, and a printing ink was prepared in the same manner as in Example 1.

Printing was carried out using a water-free lithographic printing plate using the ultraviolet curable printing inks prepared in Examples 1 to 5 and Reference Examples 1 to 4, and the stains on the non-image areas of the ink, halftone dot reproducibility, and roller fraying were evaluated. Washability etc. were evaluated using a three-point system of excellent, good, and poor, and are shown in Table 1 below. The printing machine was a Heidel monochrome machine KORD, which printed at a printing speed of 3,000 sheets/hour, and a roller ki was used for washing with kerosene. The halftone reproducibility was measured using Viewback (manufactured by Toyo Ink), and the halftone dot area ratio of the plate at a halftone dot area ratio of 50%,
Depending on the ratio to the halftone dot area ratio of the printed matter, evaluation was made as excellent within ±5 to ±10%, good within ±20%, and poor above that.

Claims (1)

[Claims] (1) An aromatic vinyl compound having 8 to 10 carbon atoms, and/or an alicyclic vinyl compound having 10 carbon atoms, and/or a typical combination, and/or a part or all of the above compounds. The -j4 compound with an aliphatic vinyl compound is: (meth) having one (meth)acryloyl group
20 to 1,000 parts by weight of acrylic prepolymer is mixed with 20 to 80 parts by weight of acrylic prepolymer.
B) is 0.1 to 10% by weight, thickener (Q force 0.5 to 10%)
A waterless lithographic printing ink which is cured by ultraviolet light and comprises 5 to 50 weight % of a pigment Cf1) and 1 to 20 weight % of a photoreaction initiator.