JPH07119382B2 - Resin for printing ink and ink for metal printing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Object of the Invention" (Field of Industrial Application) The present invention relates to a resin for metal printing ink and an ink for metal printing. In particular, the present invention relates to a resin for metal printing ink which has excellent printability for a water-based overprint varnish and can reduce misting during printing.

(Prior Art) Recently, in the field of metal printing, a solvent-based overprint varnish is being replaced by a water-based overprint varnish in view of a problem of air pollution related to a solvent, hygiene and safety in a working environment. However, a metal printing ink that has sufficient suitability for an aqueous overprint varnish and has little misting during printing has not been obtained.

(Problems to be Solved by the Invention) As a metal printing ink suitable for an aqueous overprint varnish, JP-A-62-295976, JP-B-54-22331,
Inventions such as JP-A-62-295975 and JP-A-62-295974 have been reported. In both cases, the subject of the invention relates to the solvent to be used, and used as a binder in combination with glycol or glycol monoether, oil-modified alkyd resin or oil-free alkyd resin, epoxy ester resin and the like. However, metal printing inks prepared by combining an oil-modified alkyd resin and a glycol-based or glycol monoether-based solvent are not completely suitable for water-based overprint varnishes, and gloss deterioration and coating suitability are unsatisfactory.

Some oil-free alkyd resins and epoxy ester resins are suitable for water-based overprint varnishes, but their poor pigment dispersibility does not increase the ink viscosity and causes misting during printing, which reduces the working environment. It was

The present invention relates to a resin for a printing ink, a manufacturing method, and a metal printing ink which are suitable for overprint varnishes, can reduce ink misting, and can prevent deterioration of working environment.

[Structure of the Invention] (Means for Solving Problems) That is, the present invention is a residual product obtained by reacting a branched saturated monovalent carboxylic acid having 7 to 26 carbon atoms, a polyhydric alcohol and a polyvalent carboxylic acid. It is a resin for printing inks having a hydroxyl equivalent of 50 to 500, and is an ink for metal printing mainly composed of the above resin, pigment, solvent and amino resin.

That is, the resin of the present invention reacts with a branched saturated monovalent carboxylic acid having 7 to 26 carbon atoms to improve pigment dispersibility, improve ink cohesiveness, and reduce misting during printing. Furthermore, the reaction of a branched saturated monohydric carboxylic acid having 7 to 26 carbon atoms with a polyhydric alcohol is carried out in the first step, and then a polyhydric alcohol and a polyhydric carboxylic acid are reacted to give a hydroxyl group at the terminal of the resin. Remains, the suitability of the water-based overprint varnish is improved.

Examples of the branched saturated monovalent carboxylic acid having 7 to 26 carbon atoms that can be used for the resin for printing ink of the present invention include isopentanoic acid,
Isononanoic acid, isodecanoic acid, isotridecanoic acid, isomyristic acid, isopalmitic acid, isostearic acid,
Examples include isoarachidic acid and isohexacoic acid.

Examples of the polyhydric alcohol include alkylene glycols such as ethylene glycol, neopentyl glycol, propylene glycol and butylene glycol, condensates of these glycols by etherification, trihydric alcohols such as trimethylolethane, trimethylolpropane and glycerin, and pentaerythritol. , Tetraglycerides such as diglycerin, ditrimethylolethane and ditrimethylolpropane, and polyhydric alcohols such as dipentaerythritol, tripentaerythritol and inositol can be used.

Examples of the polycarboxylic acid and its anhydride include succinic acid,
Aliphatic dicarboxylic acids such as succinic anhydride, glutaric acid, glutaric anhydride, adipic acid, pimelic acid, speric acid, azelaic acid, sebacic acid, maleic acid, maleic anhydride, fumaric acid and their alkyl esters, and their anhydrides And ester compounds can also be used, and anhydrides of aliphatic dicarboxylic acids such as tetrahydrophthalic anhydride, hexahydrophthalic anhydride and their alkyl substituents, hymic acid anhydrides and hymic acid anhydrides, phthalic anhydrides, alkyl anhydrides General polycarboxylic acid anhydrides such as polycarboxylic acid anhydrides such as phthalic acid, trimellitic anhydride and pyromellitic anhydride can be used.

In the resin of the present invention, alcohols and carboxylic acids other than the above alcohols and carboxylic acids can be used if necessary. It is also possible to use alkylene oxides of polyhydric alcohols.

The reaction of these materials will be described. First, a branched saturated monohydric carboxylic acid having 7 to 26 carbon atoms and a polyhydric alcohol are reacted in the first step, and a polyhydric alcohol and a polycarboxylic acid are reacted in the second step.

The resin of the present invention has a residual hydroxyl group, and the equivalent weight of the hydroxyl group is 50 to 500, preferably 100 to 300. If the hydroxyl equivalent is greater than 500, the metal printing ink combined with the amino resin will not increase the hardness of the coating film. The misting during printing increases.

The metal printing ink of the present invention comprises a resin according to the present invention and a boiling point.
Consists of solvent above 200 ℃, amino resin, and pigment.

Solvents with a boiling point of 200 ° C or higher include glycols such as diethylene glycol, triethylene glycol, propylene glycol, butylene glycol, etc. or mono- and dialkyl ethers of these glycols, alkyl ethers, dimethyl phthalate, diethyl phthalate, dioctyl adipate, dioctyl sebacate, etc. Plasticizers, alkylbenzenes, aliphatic ink solvents, etc. with a boiling point of 200 ° C or higher can be used. Further, an amino resin is required to cure and dry the metal printing ink of the present invention,
As the amino resin, it is possible to use guanamine resins such as benzoguanamine resin, melamine resins such as trimethylolmelamine, hexamethylolmelamine and their alkyl ethers. If necessary, an acidic catalyst can be used to accelerate the reaction between the hydroxyl group and the amino resin.

The present invention will be further described with reference to examples.

All parts in the text are parts by weight.

Example 1 Isomyristic acid (manufactured by Nissan Kagaku, 2 pentylnonanoic acid) was placed in a four-necked flask equipped with a stirrer, thermometer, cooling tube, and water separation tube
237 parts (1.04 mol), trimethylolpropane 134 parts (1
Mol) and 30 parts of commercially available xylene for industrial use, stirred and heated while blowing N ₂ gas and reacted at 230 ° C for about 15 hours. When the acid value became 10 or less, xylene was distilled off to give a pale yellow color. A transparent esterified product [1] was obtained. The residual hydroxyl equivalent of this [1] is 180.

Next, also with a stirrer, thermometer, cooling pipe, water separation pipe 4
A one-necked flask was charged with 191 parts of the above esterified product [1], 163 parts of trimethylolpropane (1.22 mol) and 30 parts of commercial industrial xylene, stirred while heating with N ₂ gas, heated, and once melted at 120 ° C or lower. Tetrahydrophthalic anhydride 152% (1 mol) was added, the temperature was raised to 200 ° C and the reaction was carried out for 10 hours. When the acid value reached 10, xylene was distilled off to obtain a transparent and viscous resin-1. It was The residual hydroxyl equivalent of this resin is 180.

Table 1 shows the synthesis conditions of Resin-2 (Example 2) and Resin-3 (Example 3) obtained by the same operation as in Example 1.

Comparative Example 1 (when the residual hydroxyl equivalent of the obtained resin exceeds 500) 71 parts of the esterified product [1] obtained in Example 1, 134 parts (1 mol) of trimethylolpropane and commercially available xylene 30 Part, charged with N ₂ gas, stirred and heated, 205 parts (1.35 mol) of tetrahydrophthalic anhydride was added after dissolution to 120 ° C or lower, heated to 200 ° C, reacted for 10 hours, and acid value was 10 At that time, xylene was distilled off to obtain a transparent and viscous comparative resin-1. The residual hydroxyl equivalent of this resin is 550.
Is.

Hereinafter, Comparative Resins 2 and 3 were obtained in the same manner as in Comparative Example 1. The synthesis conditions are shown in Table 1.

Comparative Example 2 (when a saturated monovalent carboxylic acid having less than 7 carbon atoms is used) Comparative Example 3 (when the residual hydroxyl equivalent of the obtained resin is less than 50) ・ Viscosity was measured by dissolving with resin / BTG = 1/1 and measuring with a Gardner bubble viscometer at 25 ° C.

-Weight average molecular weight was measured by high performance liquid chromatography (Column-Shordex KF804 x KF802) and converted to polystyrene.

-Solubility was evaluated as ○ when the resin / solvent to be measured = 1/1 and clear at 15 ° C, and when cloudy.

The ink evaluation of these resins will be shown.

Resin-3, Comparative resin 1-3 35-45 parts, Alken 56NT (Nisseki Chemical, alkylbenzene) 10-15 parts,
Cymel 300 (Mitsui Toatsu, hexamethylol melamine) 12 parts, Lionol Red F2B (Toyo Ink Mfg., C.
35 parts of I. pigment Red 48: 1) was made into an ink using a three-roll mill. Use ink for each. For example, it is displayed as 1-.

In the same manner as above, replace the BTG (triethylene glycol monobutyl ether, made by Nippon Emulsifier) of the part of Alken 56NT, and make other inks in the same way to make inks.

Ink evaluation includes tack (IR), flow (SR), and misting test (inkometer: 1200 rpm) during ink production.
The amount of ink splashed over 5 minutes was observed. In other words, a blank sheet was placed under the roll of the incometer and the colorability of the ink was visually judged. The coating suitability of the water-based overcoat varnish was as follows. After printing each ink on an aluminum plate for an aluminum can with an RI tester as a base, an acrylic water-based overcoat varnish A was applied.

[Contents of acrylic water-based overcoat varnish A]

The four-necked flask used in Preparation Example 1 was charged with n-butanol 10
Charge 0 parts, stir while introducing nitrogen gas,
The temperature was kept at 105 ° C., and a mixture of 15 parts of acrylic acid, 30 parts of butyl acrylate, 20 parts of ethyl acrylate, 30 parts of styrene, 5 parts of hydroxyethyl acrylate and 3 parts of benzoyl peroxide was added dropwise from a dropping tank over 3 hours. After that, the temperature was kept at 105 ° C and the reaction was carried out for 1 hour.
Parts were added, reacted for 1 hour and cooled. When the liquid temperature fell to 40 ° C or below, 18.5 parts of diethylethanolamine and 200 parts of water were added, and the solvent was distilled off together with water at 80 ° C under reduced pressure to obtain a solid content of 60% and residual n-butanol of 10%. A smooth aqueous acrylic resin solution (A) was obtained.

46.7 parts of this aqueous acrylic resin solution (A), 12.0 parts of hexamethoxymelamine, 0.2 parts of amine-blocked paratoluenesulfonic acid, 0.1 part of silicone leveling agent, 3 parts of water
3.9 parts and 7.0 parts of butyl cellosolve were mixed to form a paint.

The acrylic aqueous overcoat varnish A was applied by roll coating so that the film thickness after drying was 7 μm, and baked in a hot air oven at 200 ° C. for 90 seconds.

Painting and coating test-Gloss The coating was visually inspected.

・ Film hardness The pencil hardness of the paint film was shown by scratching.

・ Water resistance test After the printed coating was placed in a hot bath at 80 ℃ for 1 hour, the hardness of the film was measured with a pencil.

The results are shown in Table-3.

Claims (2)

[Claims] 1. A printing ink having a residual hydroxyl equivalent of 50 to 500 obtained by reacting a branched saturated monovalent carboxylic acid having 7 to 26 carbon atoms, a polyhydric alcohol and a polycarboxylic acid. Resin. 2. An ink for metal printing, which is mainly composed of the resin according to claim 1, a pigment, a solvent and an amino resin.