JPH08132755A - Offset printing method and aqueous composition therefor - Google Patents

Abstract

PURPOSE: To obtain an aqueous composition adapted to offset printing or the like by blending a copolymer P having a acrylic amide group, a copolymerizable diethylenic crosslinker and specific anionic monomer, cationic monomer. CONSTITUTION: An ionic, hydrophilic, crosslinking, water insoluble copolymer based on water swelling acrylamide with particles each having a particle size of 1 μm or below, copolymerizable diethylene crosslinker and anionic monomer represented by the formula I (wherein R is H, methyl radical, M is H, Na, K or ammonium group) or cationic monomer represented by the formula II (wherein R is the same as the formula I, Z is O, NH group, R is a methyl group, an ethyl radical, R is H, methyl group or the like, X is cl or the like, and n is 2 or 3) is blended with swelling water, ink or lacquer. These are used for offset printing.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an offset printing method and an aqueous composition for offset printing.

[0002]

2. Description of the Related Art Generally, offset printing (or lithographic printing)
Uses wet water containing isopropyl alcohol (hereinafter referred to as IPA) to improve the wetting of hydrophilic areas of offset plates and to accelerate the emulsification of water in inks or lacquers.

[0003]

[Problems to be Solved by the Invention] However, IPA
Its use has many disadvantages due to its volatility, flammability and toxicity, so it is possible to use water-soluble polymers such as carboxymethylcellulose, hydroxypropylmethylcellulose, polyvinylpyrrolidone or various glycols which can be combined with glycol ethers. It has been proposed to replace (US-A-4856646, 464)
1579, 4548645 and 4278467). However, the dampening water obtained using these products does not give the printer complete satisfaction. The inventor has proposed an offset printing method which does not require the use of IPA and which improves the printing method in terms of both the action of the ink or lacquer of the machine and the print quality (brightness, contrast, mechanical strength and color registration) I just invented it.

[0004]

The offset printing method of the present invention, when used in either wet water or ink or lacquer, or in both wet water and ink or lacquer, is ionic, Copolymer P based on acrylamide (hereinafter also referred to as AAM), which is hydrophilic, crosslinkable and water-insoluble, but is swollen in water in the form of water-swollen particles having a diameter smaller than 1 μm, copolymerizable diethylenic crosslink Agent and one or more anionic monomer of formula (I)

[0005]

[Chemical 3]

(Wherein R represents a hydrogen atom or a methyl radical and M represents a hydrogen atom, a sodium or potassium atom or an ammonium group) or one or more cationic monomers of the following formula (II) It is characterized by.

[0007]

[Chemical 4]

(Wherein R has the same meaning as above, Z represents an oxygen atom or an NH group, R ₁ represents a methyl or ethyl radical, and R ₂ represents a hydrogen atom or a methyl, ethyl or benzyl radical. , X is a chlorine atom or OSO
₃ R ₂ group (R ₂ is as defined above, and n is 2 or 3)

The expression "ionic" copolymer means either anionic or cationic copolymers.

The monomers of formula (I) may include acrylic acid, its sodium, potassium or ammonium salts, methacrylic acid and its sodium, potassium or ammonium salts.

As the monomer of formula (II), N, N-dimethylamino-2-ethyl acrylate quaternized with methyl chloride or ethyl chloride or a salt with hydrochloric acid is used as a monomer of the formula (II). Or N, N-diethylamino-2-ethyl acrylate quaternized with methyl chloride or ethyl chloride, N, N-dimethylamino-2 quaternized with hydrochloric acid or quaternized with methyl chloride or ethyl chloride -Ethyl methacrylate, (meth) acrylamidopropyl trimethyl ammonium chloride can be mentioned.

As the polymerizable diethylenic crosslinking agent,
Methylenebisacrylamide (hereinafter also referred to as MBA)
And bisacrylamide acetic acid (hereinafter, also referred to as ABAA).

As the copolymer P, a salt is partially formed with ammonia, and MBA or ABAA (particularly ABAA) is formed.
Quaternized with anionic copolymers based on acrylic acid and acrylamide and methyl chloride (hereinafter also referred to as CMA) cross-linked with MBA or ABAA (particularly ABA
Mention may be made of cationic copolymers based on N, N-dimethylamino-2-ethyl acrylate and acrylamide crosslinked with A).

As the above-mentioned copolymer, particularly, a copolymer of AAM-AA-AANH ₄ -ABAA (the molar ratio of each is 29.6-65.1-5.1-).
0.2), ---- AAM-CMA-ABAA copolymer (each molar ratio is 79.15-20.83-0.02).

The abbreviations used have the following meanings. AAM: Acrylamide AA: Acrylic acid AANH ₄ : Ammonium acrylate ABAA: Bisacrylamide acetic acid CMA: Acryloyloxy-2-ethyltrimethylammonium chloride

The copolymer P in the form of water-swollen microparticles having a diameter of less than 1 μm is known as product.

The anionic copolymer P has been particularly proposed as a thickening agent for printing with pigments (see EP-A-0325065) or as a paper coating process (see EP-A-0501846).

The cationic copolymer P is a thickening agent for the production of household softeners (see EP-A-0494554).
Is especially proposed as.

Copolymer P is a hydrophilic copolymer capable of absorbing up to about 1000 times the weight of water. Thus, when water-swollen microparticles of copolymer P with a diameter of less than 1 μm are contacted with water, they absorb up to about 1000 times the weight of water, their diameter increasing up to about 10 times the original diameter. However, their water absorption capacity depends on the degree of crosslinking. Water absorbed by the microparticles of Copolymer P is readily available. In fact, as soon as these water swollen particles are stressed, they release some of the absorbed water, and when the stress is relieved they absorb again.

In order to carry out the process of the invention under the preferred conditions, a self-reversible water-in-oil dispersion (hereinafter also referred to as D) is used, which is 1 in the dispersed aqueous phase.
The copolymer P is included under the condition of water-swollen fine particles having a diameter of less than μm.

A self-reversible water-in-oil dispersion is a dispersion in which the continuous phase is oil and the disperse phase is water, and when diluted with water, it spontaneously reverses to quickly become an oil-in-water dispersion. Means possible things. In order for this to happen, one or more oil-soluble emulsifiers having an HLB value of less than 5,
It is sufficient to further include one or more water-soluble emulsifiers having an HLB value of 8 or more (preferably 10 or more), and all emulsifiers have a total HLB value of 8 or more, preferably 10 or more.

HLB refers to the hydrophilic-lipophilic balance of emulsifiers (Kirk-Othmer, Encyclopedia.
of Chemical Technology, 3rd Edition, Volume 8, 910
~ 918).

The self-reversible water-in-oil dispersion D which can be used in the process of the invention is a dispersed aqueous phase containing the copolymer P in the form of water-swollen microparticles with a diameter of less than 1 μm,
It contains a continuous oil phase and an emulsifier system (designated E), so that the dispersion is stable at room temperature. Emulsifier system is 8
As described above, it contains not only one or more water-soluble emulsifiers having an HLB value of 10 or more, but also one or more oil-soluble emulsifiers having an HLB value of less than 5, in an appropriate amount.
Is an amount such that it has an HLB value of at least 8 and preferably at least 10.

The dispersed aqueous phase in Dispersion D is a metal, buffer, transfer agent (transfer agent) that inhibits polymerization if necessary.
agent), and common water-soluble additives such as chelating agents in addition to the copolymer P to remove the polymerization initiator. However, the total weight of these various additives should not exceed about 5% of the total weight of the aqueous phase.

The oil phase comprises one or more hydrocarbons which are liquid at room temperature and have a boiling point above 100 ° C. These hydrocarbons can include straight or branched chain paraffins and commercial cycloparaffins that are liquid at room temperature and have a boiling point of 150-350 ° C. Furthermore, it can contain various customary additives such as polymerization initiators or transfer agents in proportions not exceeding 5% of their weight.

Oil-soluble emulsifiers having an HLB value of less than 5 include sorbitan and fatty acid esters, such as sorbitan monooleate, and sorbitan sesquioleate. Examples of the water-soluble emulsifier having an HLB value of 8 or more include nonylphenyl ethoxylated with 8 mol of ethylene oxide, nonylphenyl ethoxylated with 10 mol of ethylene oxide, sorbitan hexaoleate ethoxylated with 40 mol of ethylene oxide, and 50 mol. Mention may be made of ethylene oxide ethoxylated sorbitan hexaoleate, such as ethylene oxide ethoxylated nonylphenol.

Dispersions D are known as products, some of which are widely used in the textile industry for printing with pigments. They are compatible with the inks or lacquers used in offset printing and give colloidal solutions containing the water-swollen copolymer P. They are also compatible with water in all proportions giving oil-water dispersions, in which case the particles of copolymer P are dispersed in the continuous aqueous phase.

Dispersion D can be obtained by known methods, such as the polymerization methods in water-in-oil suspensions of the reverse type, which are widely described in the literature.

To achieve this, for example, (i) a water-in-oil emulsion is prepared by adding an aqueous solution containing the monomers, and, if desired, the selected additives with one or more suitable emulsifiers. It is possible to obtain an emulsion of the reverse type consisting of minute water particles of less than 1 μm containing a monomer by stirring in a liquid hydrocarbon containing The emulsion is dispersed in a continuous oil phase and the volume (volume ratio Rv) of the aqueous phase to the total volume of the emulsion is less than 74%, preferably less than 71%. (Ii) The completely deoxygenated emulsion is then treated with azobisisobutyronitrile, AIBN, azobisamidinopropane dichlorate (ABAH), a peroxide such as sodium or ammonium persulfate, cumene hydroperoxide or It undergoes a radical polymerization reaction by introducing with stirring one or more initiators that generate free radicals, such as azo derivatives such as redox systems, (iii) then, when the polymerization reaction is over, one or more water-soluble Add an appropriate amount of emulsifier to the cooling reaction medium to obtain a total HLB of emulsifier
The value is 8 or more as a whole, preferably 10 or more. If desired, the copolymer P can be isolated from the reaction medium before adding the water-soluble emulsifier, or water- and oil-
Copolymer P can be precipitated by adding a compatible solvent (eg acetone) and isolated by filtration, which is dried and redispersed in water.

Dispersion D which can be used in the method of the present invention includes, in particular, a self-reversible water-in-oil type dispersion containing the following component weights. About 71 ± 3 aqueous phase containing about 42 ± 3% by weight of Copolymer P in the form of water-swollen microparticles with a diameter of less than 1 μm.
% Oil phase about 25 ± 2.5% mixture of emulsifiers containing 50% by weight or more of one or more emulsifiers having an overall HLB value of more than 8 and an HLB value of less than 4%

Examples of the above-mentioned dispersion liquid include those containing the following copolymers. _{──AAM-AA-AANH 4 -ABAA,} ( molar ratio 29.6-65.1-5.1-0.2), ──AAM-CMA-ABAA , ( mole ratio 79.1
5-20.83-0.02)

In order to carry out the process according to the invention in the most preferred conditions, the dispersion D as defined above, which comprises the copolymer P as defined above in the condition of water-swollen microparticles, is preferably about 0.1. 10% by weight of the aqueous composition (hereinafter,
(Also called C) is used. Aqueous Composition C, which is compatible with water, can be used directly to obtain wetting water for offset printing. This aqueous composition C is obtained by simply mixing the desired amount of dispersion D in water.

Examples of these aqueous compositions C include those containing 0.5% by weight of the dispersion D defined above.

The process of the present invention comprises the copolymer P defined above, either in wet water or in ink or lacquer,
Or very simply by adding to both the wet water and the ink or lacquer with stirring.

According to the preferred conditions for carrying out the invention, the process described above wets 0.01-3% by weight of copolymer P in the presence of the self-reversible water-in-oil dispersion D defined above. It is carried out either by adding to water and / or ink or lacquer with stirring, or by adding 0.01 to 3% by weight of copolymer P in aqueous composition C to wet water.

In the printing process by lithographic printing, in particular in the offset printing process, either the wet water or the ink or lacquer or when the copolymer P defined above is used together with the wet water and the ink or lacquer, especially during printing Having the advantages of: avoiding the use of hydroxylated compounds such as isopropyl alcohol or polyols or glycol monoethers; mitigating the emulsification of water in the ink or lacquer while improving the “offset” properties, ─ Change the tack of the ink or lacquer, the transfer of ink from one sheet to the next. And in the printed product: -improving the visual homogeneity of the flat hue, -helping the overlaying of the ink and / or lacquer-increases the gloss, especially in the case of lacquers ── It is possible to achieve good print resolution as a result of good separation between printed and non-printed areas, ── Allows printing with stronger colors in flat hues To improve print contrast

When the copolymer P dispersed in the dispersion D defined above is added to the wetting water and / or the ink or lacquer, or when the copolymer P dispersed in the aqueous composition C defined above is added to the wet water. The same result can be obtained.

The test is System Brunner SA, CH-660.
0 Locarno, a "Brunner System standard offset test form sold by a Swiss company
+ Offsets "was used.

The results of the entire test listed in Table 1 are 40 d.
0.26% by weight of the dispersion prepared according to Example 1 or 1% by weight of the dispersion prepared according to Example ² in order to obtain a surface tension on the order of ynes / cm (40 mN / m or 40 mJ / m ² ). By adding any of the
It was carried out in comparison with tests carried out with moistened water containing PA. The test described is "T4725 blue and red from the Plast rang" with an optical density of 1.5 OD.
U with e "ink and double coated" main "sold by Arjomari-Wettaggins company
Performed on a two color offset machine equipped with a V dryer.

All the following tests were then carried out on the printed sheets. ── Ink abrasion test ─ ─ Visual classification of flat hues ─ ─ Quality control: OD (optical density), trapping, gloss, dot distribution (TF-TG), ── Evaluation of image analysis quality − Flat PC% on tonal hue-Gray spectral level on tonal hue-pq. Roundness of screen dot indicated by (25% coverage area)

The ink abrasion test was 2.5 rpm at 50 rpm.
Performed using a Wallace device after 6 days at a load of g. The spread of screen dots is TF-TG
Indicated by. Trapping means that one ink overlays another. Gloss was determined using a gloss meter. Image analysis observing the perimeter of screen dots was performed after microscopic magnification: the smallest area observed was 27 μm ² .

The flat hue coverage%, as indicated above by PC%, was measured at two different magnifications. The quality of the flat hue continuity was determined using particle size curves for different working resolutions. The results followed a flat hue visual classification.

Gray spectral levels on flat hues were determined on the basis of the microdensity curve, using different expansions of the flat hue. The increase in roughness can clearly be seen as the resolution of the device increases. Regardless of the choice of magnification, the results obtained by visual classification were confirmed.

The quality of the contour of the screen dots was examined on a 25% covered screen to find the best circularity factor to determine the perimeter (indicated by pr) and the surface area of 10 screen dots. The theoretical perimeter (indicated by pt) of a perfect circle with the same area was then calculated from the observed surface area. The ratio of the actually measured perimeter (pr) minus the calculated theoretical perimeter (pt) to the theoretical perimeter (pt) represents the factor of circularity (pq):

[0045]

[0046]

Example Preparation of Dispersion D : Approximately 80% by weight of paraffinic hydrocarbon and about 20% of naphtheneic hydrocarbon having a boiling point of 310 to 342 ° C.
Mixture of liquid hydrocarbons with wt.% 92 wt.% Sorbitan sesquioleate with HLB = 3.7 8.
To a total weight of 52400 g of the oil phase cooled to 10 ° C., containing 4% by weight of monomers M 42.9% by weight of pure citric anhydride n% by weight of diethylenetriaminepentaacetic acid. Pentasodium salt of 500 ppm (that is, 7 g): water-soluble azo derivative Az defined in Table 1 is 15 pp when expressed in terms of molar ratio with respect to all monomers.
A total weight of 140,000 g of m 2 containing completely deoxygenated freshly prepared aqueous phase was added over 15 minutes under an inert atmosphere with stirring at 90 rpm.

After addition, the reaction medium was carefully deoxygenated by bubbling with nitrogen, then Brookfield viscosity determined at 20 ° C. was 3.6 ± 0.2 Pa.s. 1 to get s
20rpm using 4 shafts while maintaining the temperature at 0 ℃
Stirred vigorously under an inert atmosphere at a rate of.

The emulsion obtained, which had a temperature of 10 ° C. and was kept stirring under an inert atmosphere, contained 850 g of the hydrocarbon mixture used for the production of the oil phase.
200 pp of cumene hydroperoxide in solution
m (molar ratio with respect to monomer) was added over 5 minutes. Then, after adding this, the mixture was stirred for 5 minutes under an inert atmosphere to cause an exothermic polymerization reaction, and sodium difluride 112.5 ppm (molar ratio with respect to monomer) in a solution of 3000 g of water was added to 45
Added over minutes.

The temperature of the reaction medium after it was added was about 80 ° C. The mixture was stirred for 1 hour while maintaining this temperature, and then cooled to room temperature.

The following components were then added with stirring: 2000 g of nonylphenol ethoxylated with 8 mol of ethylene oxide (HLB = 12.3) 2000 g of nonylphenol ethoxylated with 10 mol of ethylene oxide (HLB = 13.3)

200 to 250 g of a self-plastic water-in-oil emulsion were thus obtained with the following composition: --Aqueous phase containing 42% by weight of polymer P 71.41% by weight --Oil phase 24. 3. 50% by weight of emulsifier system consisting of 51.17% by weight of emulsifier with HLB = 3.7 and 48.83% by weight of a 1/1 mixture of two emulsifiers with HLB of 12.3 and 13.3. 09% by weight

This dispersion is described in Table 1 with the following properties: Ve: Brookfield viscosity of the dispersion determined at 20 ° C. at a speed of 20 rpm with biaxial use, Vs: dispersion Brookfield viscosity of an aqueous solution containing 3.33% of Vn: Vn: 3.33% of dispersion and 0.1% of sodium chloride
Brookfield viscosity of aqueous solutions containing

[0053]

[Table 1]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Jean-Claude Siro, France 93350 Le, Burj, Avenue, de, La, División, Recle 78 (72) Inventor Claude Truve, France 91330 Jere , Ryu, De, La, Grange 18 (72) Inventor René Chaudey 38610 Venon, Shemin, de, Presenbwa (no house number) (72) Inventor Paul Maro France 78400 Chateau, Avenue, Victor, Hugo 15

Claims (7)

[Claims] 1. Ionic, when used in either wet water or ink or lacquer, or both wet water and ink or lacquer,
An acrylamide-based copolymer P which is hydrophilic, crosslinkable and water-insoluble, but is water-swellable in the form of water-swollen microparticles with a diameter of less than 1 μm, a copolymerizable diethylenic crosslinker, and one or more Anionic monomer of the following formula (I): (In the formula, R represents a hydrogen atom or a methyl radical,
Represents hydrogen, sodium or potassium atom or ammonium group) or one or more cationic monomers of the following formula (II): (In the formula, R is as defined above, Z is an oxygen atom or N
H group, R ₁ represents a methyl or ethyl radical, R ₂ represents a hydrogen atom or a methyl, ethyl or benzyl radical, X represents a chlorine atom or an OSO ₃ R ₂ group (R
₂ represents the same meaning as above), and n represents 2 or 3.
Offset printing method characterized by being carried out in the presence of. 2. Copolymer P is an anionic copolymer based on acrylic acid and acrylamide crosslinked with a diethylene monomer selected from the group comprising methylenebisacrylamide and bisacrylamidoacetic acid and partially converted to a salt with ammonia. The offset printing method according to claim 1, wherein: 3. Copolymer P, N, N-dimethyl crosslinked with a diethylene monomer selected from the group comprising methylenebisacrylamide and bisacrylamidoacetic acid, quaternized with methyl chloride or converted into a salt with hydrochloric acid. A cationic copolymer based on aminoethyl acrylate and acrylamide.
Offset printing method described. 4. The anionic copolymer is a copolymer based on acrylamide, acrylic acid, ammonium acrylate and bisacrylamidoacetic acid, and the molar ratio of each is 29.6, 65.1, 5.1, 0.2. The offset printing method according to claim 2, wherein 5. The cationic copolymer is an acrylamide-based copolymer of acryloyloxy-2-ethyltrimethylammonium chloride and bisacrylamidoacetic acid, each having a molar ratio of 20.83,
0.02, 79.15.
Offset printing method described. 6. The offset printing method according to claim 1, wherein the copolymer P is dispersed in a self-reversible water-in-oil type dispersion in the form of water-swollen fine particles. 7. A wet composition as defined in claim 1 in the form of water swollen microparticles in either wet water or an ink or lacquer, or in an aqueous composition in an offset printing process which can be used for both wet water and ink or lacquer. An aqueous composition comprising a copolymer P as described above.