JP4186087B2 - Printing ink composition for flexographic relief printing - Google Patents

Description

【００３２】
＜ベースインキの調製＞
表２の配合処方に従い、顔料（リオノルブルーＦＧ−７３３０、東洋インキ製造株式会社製）２５部と、練肉時に粘度が適度となる量のバインダー樹脂ワニスおよび溶媒との混合物をボールミルで練肉した後、さらに残りの材料を添加混合してベースインキＡ〜Ｅを調製した。
【表２】

【００３３】
＜インキ組成物の調製＞表３の配合に従い、ベースインキ、バインダー樹脂ワニス、溶媒、ワックス（ケミパールＷ２００、三井化学株式会社製）および消泡剤（ＫＭ−７０、信越化学工業社製）を攪拌混合して、実施例１〜６、比較例１〜４のインキ組成物を調製した。

【００３４】
２．インキ組成物の性能評価
各試験インキの印刷機上での粘度安定性、紙上乾燥性及び発色性を以下の方法で評価し、その結果を表３に示した。
【００３５】
＜印刷機上での粘度安定性＞
各試験インキの粘度が０．１Ｐａ・ｓとなる様に、それぞれのインキと同じ溶媒組成からなる希釈液を用いて調整した後、アニロックスロールと絞りロールでインキを版に供給する機構を備えたフレキソ２色刷り印刷機（東谷製鉄所製）を用い、各試験インキをアニロックスロールと絞りロールの間にスポイドで注下して、２０分間空運転してから、Ｋライナー（王子製紙株式会社製）に印刷した。そしてインキの増粘により印刷用紙が版に粘着する状態から、インキの印刷機上での粘度安定性を評価した。なお、試験条件は、雰囲気温度２０℃、相対湿度６０％、印刷速度６０ｍ／ｍｉｎ、乾燥機の温度６０℃とした。
Ａ：紙が版面に全く粘着する事なく印刷が可能。
Ｂ：紙が版面に粘着するが、紙剥けを起こさずに印刷が可能。
Ｃ：紙剥けを起こして印刷が不可能。
【００３６】
＜紙上乾燥性＞
前記印刷機上での粘度安定性試験の際に、印刷可能であったインキについて、印刷面が接触するガイドロールの汚れの有無から紙上乾燥性を評価した。
Ａ：ガイドロールが汚れない。
Ｂ：ガイドロールが汚れる。
【００３７】
＜発色性＞
比較例１と同一組成のインキを標準インキとし、各試験インキを０．１５ｍｍのメーヤバーでＫライナーに展色し、発色性のレベルを目視にて観察した。
Ａ：標準インキより色が明らかに鮮明と認められるものの中で比較しても、さらに上位のレベルにあるもの。
Ｂ：標準インキより色が明らかに鮮明と認められるもの中で比較すると、平均レベル以下のもの。
Ｃ：標準インキに対して鮮明とは認められないもの。
【００３８】
【表１】
【００３９】
【表２】
【００４０】
【表３】
【００４１】
【発明の効果】
以上、実施例と比較例を用いて具体的に説明したように、本発明の印刷インキ組成物は、アニロックスロールと、絞りロールもしくはドクターブレードとの間にインキを貯留し、次いで版にインキを供給するインキ供給装置を備えた印刷機で用いられた時に、印刷機上でのインキの粘度安定性、紙上乾燥性に優れ、さらに発色性も鮮明であるという効果を有するものである。[0001]
[Industrial application fields]
The present invention is used in a printing press equipped with an ink supply device that stores a small amount of ink between an anilox roll and a squeeze roll and supplies the ink to a plate. The present invention relates to a printing ink composition for flexographic relief printing having viscosity stability and drying on paper.
[0002]
[Prior art]
Conventionally, in the field of flexographic printing centering on corrugated cardboard, water-based ink compositions and glycol-type ink compositions have been selectively used taking advantage of their respective characteristics. The water-based ink composition can be printed at high speed because it dries faster than the glycol-type ink composition. However, the water-based ink composition is inferior in washability, and once it is dried on a plate, it becomes difficult to wash. . Therefore, the water-based ink composition is used for printing a large amount of printed matter in a large lot, which allows continuous operation of the printing machine at a high speed for a long time, while the glycol-type ink composition stops the printing machine. It has been used when manufacturing various types of printed matter in small lots that frequently change inks and colors.
[0003]
However, in the recent flexographic printing industry, the tendency to increase the number of small lots and various types has become stronger, and in the shortest case, printing of one lot is completed in a few minutes. As a result, the printing machine cleaning and the ink change take several times as long as the printing time, and the printing efficiency becomes very low.
[0004]
Therefore, first, in order to solve the above problems from the aspect of the printing mechanism, a small amount of ink is stored between the anilox roll and the squeeze roll, and a swash plate is provided for preventing ink from being lost, and further, washing is difficult. A printing machine that does not include an ink circulation device has been devised, and details thereof are described in, for example, Japanese Utility Model Publication No. 62-78435. In a printing machine with such a mechanism, the anilox roll and the squeeze roll are the only parts to be washed when moving to the next printing, and now it is only necessary to replace the bottle containing ink, which is extremely Various types of printed matter can be printed efficiently.
[0005]
On the other hand, since the ink circulation device is not provided, the supplied ink is always kept in contact with the atmosphere, and the solvent component evaporates without interruption. In particular, in this type of printing machine, printing is performed while the ink supply amount is suppressed as much as possible. Therefore, as soon as the solvent component evaporates, the viscosity increases and printing becomes impossible.
[0006]
Therefore, the viscosity stability of the ink on the printing press is relatively good, and in order to speed up the drying on paper, for example, 50 to 95% by weight of glycol and water are added to the total amount of the solvent of the ink. An ink composition using 5 to 50% by weight is disclosed in JP-A-1-62373.
[0007]
[Problems to be solved by the invention]
However, with such an ink composition, a clear color developability cannot be obtained, and as the amount of water used increases, the viscosity stability on the printing press decreases particularly when the amount of water used is around 50% by weight. There is a problem of doing. Accordingly, an object of the present invention is to provide a printing ink composition for flexographic relief printing that has clearer color developability, good viscosity stability on a printing press and drying on paper when printed under the severe printing conditions as described above. To provide things.
[0008]
[Means for Solving the Problems]
That is, the present invention relates to a printing ink composition for flexographic relief printing used in a printing press equipped with an ink supply device for storing ink between an anilox roll and a squeeze roll or a doctor blade and then supplying ink to a plate. 3 to 80% by weight of glycerin, 0 to 50% by weight of water, and 0 to 50% by weight of one or more solvents selected from the group of glycol and glycol derivatives with respect to the total amount of solvent in the ink composition The present invention relates to a printing ink composition for flexographic relief printing.
[0009]
The present invention is a flexographic printing ink composition mainly comprising a pigment, a binder resin and a solvent.
[0010]
As the pigment used in the present invention, those usually used in water-based and glycol-type printing inks for flexographic relief printing can be used as they are. Specifically, as inorganic pigments, titanium oxide, cadmium yellow, Bengala, antimony Examples thereof include colored pigments such as red, cobalt blue, bitumen, ultramarine blue, carbon black, and graphite, and extender pigments such as calcium carbonate, kaolin, clay, barium sulfate, aluminum hydroxide, and talc. Examples of organic pigments include soluble azo pigments, insoluble azo pigments, azo lake pigments, condensed azo pigments, copper phthalocyanine pigments, and condensed polycyclic pigments.
[0011]
These pigments are usually used in the ink composition in the range of about 1 to 50% by weight.
[0012]
Next, as the binder resin used in the present invention, those usually used in water-based and glycol-type printing inks for flexographic relief printing can be used as they are, rosin-modified maleic resin, acrylic resin, styrene-acrylic resin. At least one copolymer resin selected from the group of resins, styrene-maleic acid resins, and styrene-acrylic-maleic acid resins can be suitably used.
[0013]
The acrylic resin is an acrylic monomer, the styrene-acrylic resin is a styrene monomer and an acrylic monomer, and the styrene-maleic resin is a styrene monomer and maleic acid. The styrene monomer, and the styrene-acrylic-maleic acid resin are copolymer resins having a styrene monomer, a maleic acid monomer, and an acrylic monomer as copolymerization components.
[0014]
As acrylic monomers, acrylic acid and methacrylic acid can be used as a component to introduce the carboxyl group necessary for dissolving the resin in the solvent into the resin molecule, and other copolymerization is possible. Examples of such acrylic monomers include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and lauryl (meth) ) Acrylates, (meth) acrylic acid alkyl ester compounds such as stearyl (meth) acrylate, (meth) acrylic acid ester compounds containing aromatic rings such as benzyl (meth) acrylate, naphthyl (meth) acrylate, 2-hydroxyethyl ( (Meth) acrylate, 2-hydroxyp Pill (meth) acrylate, 3-hydroxypropyl (meth) (meth) acrylic acid hydroxyalkyl ester compounds such as acrylates can be used.
[0015]
Examples of the styrene monomer include styrene, α-methylstyrene, vinyltoluene and derivatives thereof.
[0016]
Maleic acid monomers include (anhydrous) maleic acid, monomethyl maleate, monoethyl maleate, malein as a component for introducing a carboxyl group necessary for dissolving the resin in a solvent into the resin molecule. Mention may be made of maleic acid monoalkyl esters such as monopropyl acid, monobutyl maleate, monohexyl maleate, monooctyl maleate, mono-2-ethylhexyl maleate, monolauryl maleate, monostearyl maleate and the like. Maleic acid dialkyl ester compounds such as dimethyl, diethyl maleate, and dibutyl maleate can be used.
[0017]
These copolymer resins may be added to other copolymers such as (meth) acrylamide, crotonic acid and its ester compound, itaconic acid and its ester compound, citraconic acid and its ester compound, acrylonitrile, and olefin compound as necessary. A polymerizable monomer may be used as a copolymerization component.
[0018]
The acid value of the above binder resin is preferably 100 to 300 mgKOH / g, more preferably 150 to 250 mgKOH / g. When the acid value of the resin is lower than 100 mgKOH / g, the solubility of the resin in the solvent is lowered. On the other hand, when the acid value is higher than 300 mgKOH / g, the water resistance of the ink is lowered, which is not preferable.
[0019]
In the present invention, the binder resin is used as a binder resin varnish after being dissolved in a singular or mixed solvent such as glycerin, water, glycol, glycol derivative in the presence of a basic compound. Examples of basic compounds that can be used in the present invention include inorganic basic compounds such as sodium hydroxide, potassium hydroxide, and ammonium hydroxide, and organic amine compounds such as triethylamine, monoethanolamine, and triethanolamine. In particular, a high boiling point organic amine compound is preferred in the present invention from the viewpoint of suppressing the thickening of the ink on the printing press.
[0020]
These binder resins are usually used in the ink composition in the range of about 1 to 30% by weight.
[0021]
Next, as a solvent for the ink composition of the present invention, glycerin is an essential component, and water, glycol, glycol derivatives, and the like are selectively used in combination according to the printing environment. Here, as the glycol component, diol compounds such as ethylene glycol, propylene glycol, butylene glycol, and diethylene glycol can be used, and as derivatives thereof, alkyl ether compounds such as methyl, ethyl, propyl, butyl, hexyl, and octyl of the glycol are used. , Ester compounds such as acetates and butyrate esters, and ester ether compounds can be used.
[0022]
The content ratio of each of the above solvents is 1 to at least one selected from the group consisting of glycerin 3 to 80% by weight, water 0 to 50% by weight, glycol and glycol derivatives, with respect to the total amount of the solvent in the ink composition. The solvent is 0 to 50% by weight. When the content of glycerin is less than the above range, an ink having good color developability cannot be obtained. On the other hand, when the content is increased, the drying property on paper is lowered, which is not preferable. On the other hand, if the water content exceeds 50% by weight, the viscosity stability of the ink on the printing press decreases, which is not preferable. Furthermore, from the viewpoint of clear color development and viscosity stability on a printing press, it is advantageous to contain more glycerin than glycols in the system, while from the viewpoint of drying, glycol is more advantageous than glycerin. It is more advantageous to contain a large amount of a kind. Therefore, from these viewpoints, the more preferable solvent composition is about 15 to 45% by weight of glycerin 15 to 60% by weight, water 10 to 40% by weight, one or more solvents selected from the group of glycol and glycol derivatives. .
[0023]
In addition, as a dry form of the ink composition of the present invention, as in a normal aqueous printing ink composition, a neutral compound or more of a basic compound is contained, and after printing, the solvent and the basic compound are volatilized or removed. Even in the form of penetrating into the paper, like a glycol type printing ink composition, it contains less than the neutralized amount of the basic compound, and after printing, the set state is caused by moisture absorption of the ink. It may be in the form of a so-called moisture set. Therefore, regarding the relationship between the solvent composition of the ink and the content of the basic compound, when the content of water is large, the neutralization degree of the basic compound with respect to the binder resin is preferably 100% or more, When the content of glycerin or glycol is large and the content of water is small, the neutralization degree of the basic compound with respect to the binder resin may be less than 100%.
[0024]
Furthermore, the ink composition of the present invention may contain various additives such as pigment dispersants, waxes, antifoaming agents, transferability improvers, and leveling agents.
[0025]
As a method for producing an ink composition using the above materials, first, a pigment, a binder resin varnish, a solvent and, if necessary, a pigment dispersant, a surfactant, and the like after stirring and mixing, For example, a method of kneading using a bead mill, a ball mill, a sand mill, an attritor, a roll mill, a pearl mill or the like, and further adding and mixing the remaining materials is used.
[0026]
The ink composition of the present invention is used in a printing press equipped with an ink supply device that stores ink between an anilox roll and a squeeze roll or a doctor blade and then supplies the ink to a plate. This type of printing machine usually does not have an ink circulation device. Instead, in the valley formed between the anilox roll and the squeeze roll or the doctor blade, a shielding plate or air curtain is used to prevent ink from flowing out. Etc., and a mechanism for storing ink in the valley portion. A small amount of ink contained in a bottle-type container is poured into the valley by an ink supply device called a tubing device, and the entire printing operation is performed in a non-circulating state.
[0027]
Therefore, the ink composition is always in contact with the atmosphere, and the solvent component will evaporate without interruption, but by using glycerin as the solvent component, the viscosity stability of the ink on the printing press is excellent, Furthermore, it has a clear color developability.
[0028]
EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited to these Examples. Unless otherwise specified, “parts” and “%” in this example represent “parts by weight” and “% by weight”.
[0029]
【Example】
1. Preparation of ink <Binder resin synthesis>
Binder resin production example 1
A four-necked flask equipped with a stirrer, a cooling tube, and a nitrogen gas introduction tube was charged with 600 parts of ethyl acetate and heated to 75 to 85 ° C., while introducing nitrogen gas, 128 parts of methacrylic acid, 92 parts of methyl methacrylate Then, a mixture of 100 parts of butyl acrylate, 80 parts of styrene and 4 parts of ditertiary butyl peroxide as an initiator was added dropwise over 1.5 hours, and further copolymerized for 2 hours while maintaining the same temperature. Under reduced pressure, a styrene-acrylic copolymer resin (binder resin No. 1) having an acid value of 180 mgKOH / g and a weight average molecular weight of 40000 was obtained.
[0030]
Binder resin production example 2
A four-necked flask equipped with a stirrer, a condenser tube, and a nitrogen gas introduction tube was charged with 600 parts of ethyl acetate and heated to 75 to 85 ° C., while introducing nitrogen gas, 225 parts of monobutyl maleic acid, maleic anhydride A mixture of 20 parts, 155 parts of styrene, and 4 parts of ditertiary butyl peroxide as an initiator was added dropwise over 1.5 hours, and further copolymerized for 2 hours while maintaining the same temperature. Then, the solvent was distilled off under reduced pressure. To give a styrene-maleic acid copolymer resin (binder resin No. 2) having an acid value of 234 mgKOH / g and a weight average molecular weight of 28000.
[0031]
<Manufacture of binder resin varnish>
According to the formulation of Table 1, the binder resin was stirred and added into a solvent in which the basic compound was dissolved, and the temperature was raised to 80 ° C. to prepare binder resin varnishes A to E.
[Table 1]

[0032]
<Preparation of base ink>
In accordance with the formulation of Table 2, after ball milling a mixture of 25 parts of pigment (Lionor Blue FG-7330, manufactured by Toyo Ink Manufacturing Co., Ltd.) and a binder resin varnish and a solvent having an appropriate viscosity at the time of milling with a ball mill Further, the remaining materials were added and mixed to prepare base inks A to E.
[Table 2]

[0033]
<Preparation of ink composition> Stir the base ink, binder resin varnish, solvent, wax (Kemipearl W200, manufactured by Mitsui Chemicals) and antifoaming agent (KM-70, manufactured by Shin-Etsu Chemical Co., Ltd.) in accordance with the composition shown in Table 3. By mixing, ink compositions of Examples 1 to 6 and Comparative Examples 1 to 4 were prepared.

[0034]
2. Performance Evaluation of Ink Composition Viscosity stability, dryness on paper and color developability of each test ink on a printing press were evaluated by the following methods. The results are shown in Table 3.
[0035]
<Viscosity stability on printing press>
After adjusting using a diluent having the same solvent composition as each ink so that the viscosity of each test ink is 0.1 Pa · s, a mechanism for supplying ink to the plate with an anilox roll and a squeeze roll is provided. Using a flexo two-color printing machine (manufactured by Higashitani Steel Works), each test ink was poured between the anilox roll and the squeeze roll with a spoid and allowed to run for 20 minutes, and then K liner (manufactured by Oji Paper Co., Ltd.) Printed on. Then, the viscosity stability of the ink on the printing press was evaluated from the state where the printing paper adhered to the plate due to the thickening of the ink. The test conditions were an atmospheric temperature of 20 ° C., a relative humidity of 60%, a printing speed of 60 m / min, and a dryer temperature of 60 ° C.
A: Printing is possible without the paper sticking to the printing plate.
B: Paper sticks to the plate surface, but printing is possible without causing paper peeling.
C: Printing is impossible due to paper peeling.
[0036]
<Dry on paper>
In the viscosity stability test on the printing press, the ink on which printing was possible was evaluated for the drying property on paper from the presence / absence of stains on the guide roll contacting the printing surface.
A: The guide roll is not soiled.
B: The guide roll becomes dirty.
[0037]
<Color development>
An ink having the same composition as Comparative Example 1 was used as a standard ink, and each test ink was developed on a K liner with a 0.15 mm Mayer bar, and the level of color developability was visually observed.
A: Even if it is recognized that the color is clearly clearer than the standard ink, it is at a higher level.
B: When the color is clearly clearer than the standard ink, it is below the average level.
C: What is not recognized as clear with respect to standard ink.
[0038]
[Table 1]
[0039]
[Table 2]
[0040]
[Table 3]
[0041]
【The invention's effect】
As described above in detail with reference to Examples and Comparative Examples, the printing ink composition of the present invention stores ink between an anilox roll and a squeeze roll or a doctor blade, and then puts the ink on the plate. When used in a printer equipped with an ink supply device to supply, the ink has the effects of excellent viscosity stability of the ink on the printer, drying on paper, and clear color development.

Claims (1)

Ink is stored between an anilox roll and a squeeze roll or a doctor blade, and then dissolved in a solvent in the presence of pigments and basic compounds used in a printing press equipped with an ink supply device for supplying ink to the plate. At least one selected from the group consisting of rosin-modified maleic resin, acrylic resin, styrene-acrylic resin, styrene-maleic resin, and styrene-acrylic-maleic resin that can be used as a binder resin varnish. In a flexographic relief printing ink composition comprising a binder resin and a solvent as main components , glycerin is 15 to 60% by weight, water is 10 to 40% by weight, glycol and glycol derivatives based on the total amount of the solvent in the ink composition characterized in that it contains one or more solvents selected from the group of 15 to 45 wt% Flexographic relief printing ink composition.