JP5598648B2 - Resin for offset printing ink and offset printing ink - Google Patents

Description

The present invention relates to a resin for offset printing ink and an offset printing ink using the same.

In recent offset printing technology, active energy ray curing that can be cured instantaneously by irradiating active energy rays such as ultraviolet rays from the expectation for low productivity and high productivity of ink to cope with environmental problems. The use of mold printing ink compositions is underway. Specific examples of the active energy ray-curable resin include a printing ink composition containing unsaturated polyester, epoxy acrylate, urethane acrylate, a reactive diluent, and a photoinitiator, and those that are reacted and cured by irradiation with ultraviolet rays. Are known.
Among them, as suitable for offset printing, Patent Document 1 discloses that an ink composition containing a specific reactive resin, a reactive diluent and a photoinitiator containing styrene or the like as a copolymerization component is reacted and cured with ultraviolet rays. Thus, an invention of a printing ink excellent in adhesion to a substrate, high hardness, wear resistance, and the like is described.
However, as the printing machine speeds up, misting (a large amount of ink mist is scattered, the working environment during printing deteriorates, and production efficiency is reduced) and blocking occur while having various performances of printing ink. No printing ink has been obtained.

Japanese Patent Laid-Open No. 10-17812

The present invention is incorporated into an active energy ray-curable offset printing ink, whereby various performances of the printing ink (adhesion, coating film hardness, emulsification, image reproducibility, glossiness, blocking resistance, coating film resistance, An object of the present invention is to provide an offset printing ink resin capable of reducing the mist amount of printing ink while maintaining smoothness and the like, and an active energy ray-curable offset printing ink using the resin.

The present inventor uses, as a resin component, a copolymer obtained by polymerizing styrenes, (meth) acrylic acid alkyl ester, a hydrophilic group-containing vinyl monomer, and a predetermined amount of (meth) acrylonitrile, The above-mentioned problem can be achieved by mixing a resin having a weight average molecular weight (Mw) and a glass transition temperature (Tg) adjusted to a predetermined range into a composition of an active energy ray-curable printing ink for offset printing. The headline and the present invention were completed.
That is, the present invention
A copolymer obtained by polymerizing monomer components containing (a) styrenes, (b) (meth) acrylic acid alkyl ester, (c) hydrophilic group-containing vinyl monomer and (d) (meth) acrylonitrile. Te, the percentage use of each monomer component to total monomer components used in the copolymer, (a) component 60 to 90 wt%, (b) component 5-39% by weight, (c) component to 25 wt% (D) Resin for offset printing ink having 3 to 15% by weight of component , weight average molecular weight (Mw) of 4,500 to 15,000 and glass transition temperature (Tg) of 70 to 100 ° C. A),
About.

By using the resin for an active energy ray-curable offset printing ink of the present invention, various ink performances (adhesion, coating film hardness, emulsifying property, image reproducibility, glossiness, blocking resistance, coating film smoothness, etc.) can be obtained. It is possible to obtain an active energy ray-curable offset printing ink that can reduce the mist amount of printing ink even in high-speed printing.

The resin for offset printing ink (A) of the present invention comprises (a) styrenes (hereinafter referred to as (a) component), (b) (meth) acrylic acid alkyl ester (hereinafter referred to as (b) component), (c) a hydrophilic group-containing vinyl monomer (hereinafter, referred to as component (c).) and (d) (meth) acrylonitrile (hereinafter, (d). referred to as component) co-monomer component containing each predetermined amount It is obtained by polymerization.
Although it does not specifically limit as (a) component used for this invention, Specifically, in addition to styrene, (alpha) -methylstyrene, etc., the styrene compound which has an at least 1 C1-C4 alkyl group in an aromatic ring. Etc. Moreover, only 1 type of these may be used independently, and 2 or more types may be used together.

As the component (b) used in the present invention, any component having no polymerizable functional group other than the (meth) acryloyl group can be used without particular limitation. Examples thereof include methyl acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, cyclohexyl (meth) acrylate, and the like. One of these can be used alone, or two or more can be used. Among these, from the viewpoint of solubility in the reactive diluent (B) and blocking resistance, the (meth) acrylic acid alkyl ester is preferably one having an alkyl group having 1 to 20 carbon atoms.

  The component (c) used in the present invention is a polymerizable vinyl monomer having a hydrophilic group as a functional group. Examples of the hydrophilic group include a sulfonyl group, a carboxyl group, a hydroxyl group, a phosphoric acid group, and an amide group. Of these, vinyl monomers containing any one hydrophilic group selected from the group consisting of a carboxyl group, a hydroxyl group and an amide group are preferred from the viewpoints of emulsification suitability and storage stability after inking. Specific examples of vinyl monomers having a carboxyl group as a hydrophilic group include (meth) acrylic acid, (meth) acrylic acid dimer and other (meth) acrylic oligomers, hydroxy (meth) acrylate and anhydride adducts. For example, 2- (meth) acryloylethylsuccinic acid, 2- (meth) acryloylethylphthalic acid, 2- (meth) acryloylethylhexahydrophthalic acid, 2- (meth) acryloylethylchlorendic acid, etc. Is mentioned. Specific examples of the vinyl monomer having a hydroxyl group as a hydrophilic group include 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 3-chlorohydroxypropyl acrylate. Specific examples of the vinyl monomer having an amide group as a hydrophilic group include acrylamide, 2-hydroxyethylacrylamide, N, N-dimethylacrylamide, and acryloylmorpholine. Examples of the vinyl monomer having a phosphate group as a hydrophilic group include methacryloyloxyethylphosphonic acid and vinylphosphonic acid. Examples of the vinyl monomer having a sulfonyl group as a hydrophilic group include vinyl sulfonic acid and (meth) allyl sulfonic acid.

The offset printing ink resin (A) of the present invention further contains a component (d) as a copolymerization component. By containing the component (d), the resulting offset printing ink has excellent ink fluidity, so that the smoothness of the printed coating film is improved and the appearance of the printed surface is improved. The use ratio of (meth) acrylonitrile includes all monomer components used in the copolymer, that is, at least all the components (a) to (d), and when other components described later are used, the monomers including them The content is 3 to 15% by weight based on the total amount of the components (hereinafter the same). When the proportion of component (d) used is less than 3% by weight, the effect of improving the appearance of the printed surface is insufficient, and when it exceeds 15% by weight, other physical properties such as adhesion become insufficient.

The amount of each of the monomer components (component (a), component (b) and component (c)) other than the component (d) may be appropriately determined depending on the application, but is usually used for a copolymer. (A) about 60 to 90% by weight of component, (b) about 5 to 39% by weight of component, and (c) about 1 to 25% by weight of component, more preferably (A) 70 to 85% by weight of component, (b) 10 to 28.5% by weight of component (c) and 1.5 to 20% by weight of component. By keeping the use amount of each monomer component within the above range, it is possible to appropriately maintain a balance of various properties as a printing ink, such as misting resistance, adhesion, blocking resistance, fluidity of printing ink, and emulsification suitability. it can.
In the present invention, other vinyl compounds can be used in order to improve the adhesion and hardness after curing within the range in which the offset suitability can be maintained. Specifically, aromatic monomers such as benzyl (meth) acrylate, phenoxyethyl acrylate, p-cumylphenol EO-modified (meth) acrylate, and diallyl phthalate. Cyclohexane (meth) acrylate, isophorone (meth) acrylate, tricyclodecyl (meth) acrylate, dicyclopentenyl (meth) acrylate, adamantyl (meth) acrylate and other alicyclic monomers, glycidyl (meth) acrylate, oxetane ( Cyclic ether monomers such as (meth) acrylate, tetrafuryl (meth) acrylate, tetrafuryl EO modified (meth) acrylate, tetrafuryl caprolactone modified (meth) acrylate, and imides such as N- (meth) acryloyloxyethyl hexahydrophthalimide System monomers and the like. It is preferable to use other vinyl compounds in a range not exceeding 30% with respect to the total monomer components from the viewpoint of ensuring offset suitability of the obtained resin.

The polymerization method of the resin for offset printing ink (A) (copolymer) of the present invention is not particularly limited, and a known radical polymerization method can be employed. Radical polymerization is obtained by heating in the presence of a radical polymerization initiator. It does not specifically limit as a radical polymerization initiator, A well-known thing can be used. Specific examples include inorganic peroxides such as hydrogen peroxide, ammonium persulfate, and potassium persulfate, organic peroxides such as benzoyl peroxide, dicumyl peroxide, and lauryl peroxide, 2,2′-azobisisobutyrate. Examples include azo compounds such as rhonitrile, dimethyl-2,2′-azobisisobutyrate, and the like. Moreover, these 1 type may be used independently and may be used in combination of 2 or more types. In addition, it is preferable that the usage-amount of a radical polymerization initiator shall be about 1-10 weight part with respect to 100 weight part of all the monomer components. In addition, you may use a chain transfer agent etc. as needed. Specific examples of the chain transfer agent include lauryl mercaptan, dodecyl mercaptan, 2-mercaptobenzothiazole, bromotrichloromethane and the like. These may be used alone or in combination of two or more. The amount of the chain transfer agent used is preferably about 0.01 to 5 parts by weight with respect to 100 parts by weight of all monomer components.

The resin (A) for offset printing ink thus obtained has a weight average molecular weight (Mw) of about 4,500 to 15,000 (preferably about 5,000 to 13,000), and a glass transition temperature (Tg) of 70. It is necessary to adjust to about ~ 100 ° C. When the weight average molecular weight (Mw) is less than 4,500, the blocking resistance is deteriorated, and when it exceeds 15,000, the misting resistance is deteriorated. Further, when the glass transition temperature (Tg) is lower than 70 ° C., the misting resistance and blocking resistance are deteriorated. When the glass transition temperature (Tg) exceeds 100 ° C., the viscosity of the printing ink resin (A) becomes too high and is sufficient as an ink component. It becomes impossible to mix a proper amount.
In addition, a weight average molecular weight (Mw) is a polystyrene conversion value by a gel permeation chromatography method.

To the resin for offset printing ink (A) of the present invention, a reactive diluent (B) that is a monomer component that is cured by active energy rays such as ultraviolet rays, an ink component such as a photoinitiator, and an ink pigment as necessary. By mixing, an active energy ray-curable offset printing ink can be obtained.

Specific examples of the reactive diluent (B) used in the active energy ray-curable offset printing ink of the present invention include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, and triethylene glycol di (meth) acrylate. , Polyethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, 1,3 butylene glycol di (meth) acrylate, 1,6 hexanediol di (meth) acrylate, 1, 9 Nonanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 2,2bis [4-{(meth) acryloxy-diethoxy} phenyl] propane, 2,2bis [4-{(meth) acryloxyate Si} phenyl] propane, 2,2bis [4-{(meth) acryloxy polyethoxy} phenyl] propane, 2,2 bis [4-{(meth) acryloxy dipropoxy} phenyl] propane, 2,2 bis [4 And bifunctional (meth) acrylic monomers such as-{(meth) acryloxypropoxy} phenyl] propane and 2,2bis [4-{(meth) acryloxy-polypropoxy} phenyl] propane.

Also, trimethylolpropane tri (meth) acrylate, tetramethylolmethane tri (meth) acrylate, tetramethylolethane tri (meth) acrylate, tetramethylolmethane tetra (meth) acrylate, ethylene oxide (EO) modified trimethylolpropane tri (meth) Examples thereof include tri- or higher functional (meth) acrylic monomers such as acrylate and dipentaerythritol hexa (meth) acrylate.

As a use ratio of the resin for offset printing ink (A) and the reactive diluent (B) of the present invention, the reactive diluent is usually 25 to 400 with respect to 100 parts by weight of the resin for offset printing ink (A). About parts by weight, preferably 60 to 230 parts by weight. When the amount of the reactive diluent (B) used is less than 25 parts by weight, the blocking resistance and curability tend to deteriorate, and when it exceeds 400 parts by weight, the adhesiveness and misting resistance tend to decrease. It is in. The viscosity of the composition obtained in the present invention is preferably 0.1 to 500 Pa · s (25 ° C.). In order to obtain a low-viscosity composition below this range, it is necessary to add more (meth) acrylic monomers, which is not preferable. A high-viscosity composition exceeding this range is not suitable for workability (inking). This is not preferable because of poor workability at the time.

It does not specifically limit as a photoinitiator, Various well-known things can be used. Specific examples thereof include benzophenone, o-benzoylbenzoic acid methyl ester, p-dimethylaminobenzoic acid ester, p-dimethylacetophenone, thioxanthone, alkylthioxanthone, and amines. Commercially available products such as Darocur 1173, Irgacure 651, Irgacure 184, Irgacure 907 (all manufactured by Ciba Japan) may be used as they are. As a usage-amount of a photoinitiator, it is preferable to use about 0.1-10 weight part normally with respect to 100 weight part of total amounts of the ink for offset printing, and a reactive diluent (B).

The pigment used in the offset printing ink of the present invention is not particularly limited, and a commonly used inorganic or organic pigment can be blended. Specific examples include white pigments such as titanium oxide, zinc white, lead white, lithobon, and antimony oxide, black pigments such as aniline black, iron black, and carbon black, yellow lead, yellow iron oxide, titanium yellow, and Hansa Yellow (10G 5G, 3G, etc.), yellow pigments such as disazo yellow, benzine yellow, and permanent yellow, orange pigments such as chrome vermilion, permanent orange, balkan first orange, indanthrene brilliant orange, iron oxide, permanent brown, para brown Brown pigments such as Bengala, Cadmium Red, Antimony Zhu, Permanent Red, Rhodamine Lake, Alizarin Lake, Thioindigo Red, PV Carmine, Monolite First Red, Quinacdrine Red Pigment, Cobalt Purple Purple pigments such as manganese purple, first violet, methyl violet lake, indanthrene brilliant violet, dioxazine violet, ultramarine, bitumen, cobalt blue, alkali blue lake, peacock blue lake, Victoria blue lake, metal free phthalocyanine blue, copper phthalocyanine Blue pigments such as blue, indanthrene blue, indigo, chrome green, chromium oxide, emerald green, naphthol green, green gold, acid green lake, malachite green lake, phthalocyanine green, polychlorobrom copper phthalocyanine, etc. Examples include various fluorescent pigments and metal powder pigments. These pigments are preferably blended in the range of about 1 to 50 parts by weight, more preferably 5 to 30 parts by weight, with respect to 100 parts by weight of offset printing ink.

The active energy ray-curable offset printing ink of the present invention contains the resin for printing ink of the present invention, a polymerizable monomer, and a pigment as essential components. Sensitizers, antioxidants, light stabilizers, and leveling agents can also be used. These optional components are preferably blended in an amount such that the total amount thereof is in the range of about 100 parts by weight or less with respect to 100 parts by weight of the offset printing ink. Furthermore, polymerization inhibitors such as hydroquinone, hydroquinone monomethyl ether, phenothiazine, and N-nitrosophenylhydroxylamine aluminum salt can be blended. When blending a polymerization inhibitor, it is preferably used in the range of about 0.01 to 2 parts by weight with respect to the offset printing ink.

Hereinafter, the present invention will be specifically described with reference to production examples and examples. Hereinafter, “parts” means parts by weight.
In addition, the glass transition point and the weight average molecular weight were calculated | required with the following method as a characteristic value of resin.

<Glass transition point (Tg)>
Tg (° C.) was calculated by the following formula.
(Form of FOX)
1 / Tg (K) = W1 / Tg1 + W2 / Tg2 + W3 / Tg3 + ... + Wn / Tgn
W1 + W2 + W3 + ... + Wn = 1
[Wn represents the weight fraction of each monomer, and Tgn represents the glass transition point (absolute temperature K) of each homopolymer. However, n is an integer. ]
Conversion to Celsius temperature (° C) Tg (° C) = Tg (K)-273

<Weight average molecular weight>
The weight average molecular weight was calculated | required as a polystyrene conversion value measured in the THF solvent by the gel permeation chromatography (GPC). As the GPC apparatus, HLC-8020 (manufactured by Tosoh Corporation) was used, and as the column, TSKgel superHZM (manufactured by Tosoh Corporation) was used.

Example 1 (Production of resin for offset printing ink)
100 parts of xylene are added to a reaction vessel equipped with a stirrer, a reflux condenser with a water separator and a thermometer, and 75 parts of styrene, 7 parts of butyl acrylate, 10 parts of stearyl methacrylate, 3 parts of 98% acrylic acid solution, acrylonitrile are added to the dropping funnel. 5 parts were charged, 6 parts of 2,2′-azobis (2-methylbutyronitrile) (ABN-E) was added as a polymerization initiator, and a dropping polymerization reaction was carried out under reflux and stirring for 1.5 hours at 140 ° C. Incubated for 1 hour. Thereafter, the temperature was raised to 160 ° C., and the solvent was distilled off while continuing to stir at normal pressure. Further, the temperature was 6.67 KPa. The pressure was reduced below, and the solvent was completely distilled off to obtain 100 g of resin (A) for offset printing ink. The obtained resin for offset printing ink (A) had a glass transition point of 75.9 ° C. and a weight average molecular weight of 7,450. The results are shown in Table 1.

Examples 2 to 8 and Comparative Examples 1 to 8 (Production of resin for offset printing ink)
It manufactured like Example 1 except having changed the kind and usage-amount of the structural monomer of resin to the thing of Tables 1-2, respectively. The results are shown in Tables 1-2.

Abbreviations in Table 1 and Table 2 have the following meanings.
BMA; butyl methacrylate BA; butyl acrylate SMA; stearyl methacrylate ACMO; acryloylmorpholine HEMA; 2-hydroxyethyl methacrylate 98% AA; acrylic acid solution ABN-E; 2,2'-azobis (2-methylbutyronitrile )

(Preparation of clear varnish)
With respect to 50 parts of the resin for offset printing inks of Examples 1 to 8 and Comparative Examples 1 to 8 obtained, 50 parts of trimethylolpropane tri (meth) acrylate as a reactive diluent (B), under air bubbling, 130 A clear varnish was obtained by stirring and dissolving at 1 ° C. for 1 hour.

(Evaluation by clear varnish)
The performance of the clear varnish obtained in the above Examples and Comparative Examples was evaluated using the following method. The results are shown in Tables 3-4.

<Varnish viscosity (Pa · s / 25 ° C)>
The viscosity of the clear varnish at 25 ° C. was measured with an E-type viscometer.

<Emulsification suitability test>
A mixture of clear varnish and xylene in a weight ratio of 1: 2 in a glass test tube (inner diameter 18 mm × height 180 mm × thickness 1.2 mm, trade name PYREX (registered trademark) TEST18, manufactured by Iwaki Glass Co., Ltd.) 7.5 g of distilled water and 7.5 g of distilled water were collected, put a rubber stopper at the opening of the test tube, emulsified by shaking up and down 30 times, allowed to stand, and then the varnish layer and the aqueous layer were completely separated. The time until was measured. The separation time suitable for offset printing is 1 minute 30 seconds to 6 minutes.

<Blocking resistance test>
Dissolve 5 parts of Irgacure 184 (Ciba Japan Co., Ltd.) as a photopolymerization initiator in 100 parts of clear varnish, apply it to art paper with a film thickness of about 5 μm using bar coater # 3, and then use a high-pressure mercury air-cooled lamp. (120 W / cm) was used for ultraviolet irradiation under conditions of an irradiation distance of 10 cm, a belt speed of 10 m / min, and an irradiation dose of about 140 mJ / cm 2 to form a cured film. Next, two test pieces obtained by cutting the obtained cured film into 5 cm squares were prepared, the coating surfaces were overlapped, and 1375 g of weight was placed thereon, and placed in a thermostatic chamber (23 ° C., humidity 50%) for 20 hours. Left to stand. Then, when peeling the coated surfaces, blocking resistance was evaluated based on the following evaluation criteria.
○: 0% film peeling
Δ: film peeling 1% to 20%
X: Film peeling is 21% or more

<Adhesion test>
The cured film obtained in the same manner as in the blocking resistance test was made into a grid with polyethylene terephthalate and polypropylene film according to JIS K 5400, and then a cellophane tape peel test was performed and evaluated based on the following evaluation criteria.
○: 90% or more of the cured film does not peel off.
Δ: Less than 90% to about 50% of the cured film peels off.
X: The cured film is completely peeled off.

(Evaluation with printing ink)
Printing inks were prepared using the clear varnishes of the Examples and Comparative Examples, and the performance was evaluated using the following methods for misting resistance and printing ink fluidity. The results are shown in Table 3 and Table 4.

<Missing resistance>
For 100 parts of clear varnish of each example and comparative example, 10 parts of Irgacure 907 (manufactured by Ciba Japan) as a photopolymerization initiator and disazo yellow (manufactured by Dainichi Seika Kogyo Co., Ltd.) Seika Fast Yellow 2300 as a pigment: C. I-Pigment Yellow 12) 12 parts were mixed, kneaded with a three-roll mill, and adjusted appropriately so that the tack value at 38 ° C. and 1200 rpm was 25 ± 5, to prepare a printing ink.
1.30 g of each ink obtained was developed on an incometer (manufactured by Toyo Seiki Co., Ltd.), rotated at a roll temperature of 38 ° C. and 1200 rpm for 1 minute, and the degree of ink splatter on white paper placed directly under the roll was determined. Using a Gretag color difference meter (manufactured by Gretag Macbeth), an average value measured arbitrarily at five locations is obtained, and a value (ΔY) obtained by subtracting a blank value (previously measured value of white paper measured by the same method) is obtained. It was evaluated by. “Unmeasurable” in Table 4 indicates a very poor misting property where the ink is scattered in a lump.
A: ΔY is 0.10 or less B: ΔY is 0.11 to 0.30
Δ: ΔY is 0.31 to 0.50
X: ΔY is 0.51 or more

<Printing ink fluidity>
To 100 parts of the clear varnish of each example and comparative example, 10 parts of Irgacure 907 (manufactured by Ciba Japan) as a photopolymerization initiator and 10 parts of carbon black (Raven 1035 from Colombian Carbon Co.) as a pigment are mixed. A printing ink was prepared by kneading with a three-roll mill and adjusting it appropriately so that the tack value at 38 ° C. and 1200 rpm was 25 ± 5.
1.30 g of each of the obtained inks was collected, dropped on a glass plate with an inclination angle of 60 °, and the flowed distance was measured after 15 minutes. In addition, as a passing standard of printing ink fluidity | liquidity, the distance which flowed is a thing of 50 mm or more.
The results are shown in Table 3 and Table 4.

The abbreviations in Tables 3 to 4 mean the following contents.
TMPTA; trimethylolpropane tri (meth) acrylate PET; polyethylene terephthalate PP; polypropylene

Claims (3)

A copolymer obtained by polymerizing monomer components containing (a) styrenes, (b) (meth) acrylic acid alkyl ester, (c) hydrophilic group-containing vinyl monomer and (d) (meth) acrylonitrile. Te, the percentage use of each monomer component to total monomer components used in the copolymer, (a) component 60 to 90 wt%, (b) component 5-39% by weight, (c) component to 25 wt% (D) Resin for offset printing ink having 3 to 15% by weight of component , weight average molecular weight (Mw) of 4,500 to 15,000 and glass transition temperature (Tg) of 70 to 100 ° C. A). Hydrophilic groups (c) component, a carboxyl group, any one type of claim 1 Symbol mounting of an offset printing ink resin selected from the group consisting of hydroxyl groups and amide groups (A). The offset printing ink containing the resin (A) for offset printing inks of Claim 1 or 2, and the reactive diluent (B).