HK1173171A - Printing ink composition for metal and printed metal sheet obtained using same - Google Patents

Description

Metal printing ink composition and printed metal plate using same

Technical Field

The present invention relates to a metallic printing ink composition which is a printing ink used in decorative cans, three-piece beverage cans, food cans, and the like, and has high gloss, high processability, and excellent printability, and a printed metal sheet using the same.

Background

At present, metal printing is roughly classified into the following two modes: a method of processing a metal into a cylindrical shape and then printing the metal by a relief offset printing method; and a method of printing a sheet-like metal plate by a lithographic offset printing method and then processing the plate into a cylindrical shape in a subsequent step, wherein printing is mainly performed by a lithographic offset printing method for a decorative can, a three-piece beverage can, a food can, and the like. The curing method of the metallic printing ink for printing by the offset lithography method includes curing by ultraviolet irradiation and oxidative polymerization curing by heating, but in applications requiring high processability, a method of performing thermal curing by oxidative polymerization of an alkyd resin modified with a drying oil and a drying oil fatty acid is frequently used.

In addition, it is known that the processability in a metallic printing ink changes with the content of vegetable oil fatty acid used in alkyd resin (patent document 1). In general, an alkyd resin having a large content of vegetable oil fatty acid has poor workability, and an alkyd resin having a small content of vegetable oil fatty acid has good workability. Therefore, since an alkyd resin having a small content of vegetable oil fatty acid is used in a high-processability type ink, the printability such as solubility, transferability and on-machine stability of the resin is deteriorated as compared with an ink using an alkyd resin having a large content of vegetable oil fatty acid.

Furthermore, alkyd resins having a large iodine value (unit is the number of g of iodine bound to 100g of sample) have a short distance between crosslinking points, a fine mesh structure of the resin, and poor flexibility. On the other hand, alkyd resins having a small iodine value have a long distance between crosslinking points, a coarse mesh structure, and increased flexibility. Thus, the processability of metal printing inks using these alkyds reflects the flexibility of the alkyds.

Therefore, the metallic ink manufacturer prepares 2 types of inks, prepares a general type with importance attached to printability for applications requiring no workability, and prepares a high workability type for applications requiring workability. However, in recent years, as a part of rationalization for can makers and metal printing manufacturers, ink manufacturers have been required to develop metal printing inks for sheet materials (シート) that have both high processability and printability.

The gloss in metal printing is affected by the smoothness, i.e., leveling, of the coating film surface of the printing ink. Although the gloss has not been satisfactory, there is still room for improvement.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2004-285303

Patent document 2: japanese laid-open patent publication No. 2001-31889

Disclosure of Invention

Problems to be solved by the invention

The present invention has been made to solve the above problems, and an object of the present invention is to provide a metallic printing ink composition having high gloss and high processability and excellent printability, and further to provide a printed metal plate printed using the ink composition.

Means for solving the problems

As a result of intensive studies, the present inventors have found that the above object can be achieved by adopting the following configuration, and have completed the present invention.

That is, the metal printing ink composition according to the present invention is a metal printing ink composition containing a pigment, an alkyd resin, and a hydrocarbon solvent, wherein the proportion of vegetable oil fatty acids constituting the alkyd resin is 35 to 65% by mass, and 15 to 100% by mol of the polyol component is tris (2-hydroxyethyl) isocyanurate (THEIC).

In the invention, the iodine value of the alkyd resin is preferably 55-130.

The present invention also relates to a printed metal plate having an ink layer formed using the metal printing ink composition of the present invention on a metal plate or a metal substrate plate having a primer coating layer provided on the metal plate.

ADVANTAGEOUS EFFECTS OF INVENTION

The ink composition of the present invention can provide a metal plate having excellent printability and high gloss and high workability after printing. Is particularly useful in printing inks for decorative cans, three-piece beverage cans, food cans, and the like.

Detailed Description

The components used in the metallic printing ink composition of the present invention will be described in detail below.

(alkyd resin)

The alkyd resin used in the metal printing ink composition of the present invention is a resin modified with oil, fatty acid, or the like, having a skeleton of a condensate of a polybasic acid and a polyhydric alcohol in which tris (2-hydroxyethyl) isocyanurate is used as a part or all thereof; the production method is not particularly limited, and known methods such as a transesterification method using oil as a raw material and a fatty acid method using fatty acid as a raw material can be used.

In the present invention, tris (2-hydroxyethyl) isocyanurate used in the polyol component constituting the alkyd resin has a six-membered ring structure in which hydroxyl groups are present in three directions of symmetry. When a condensate of a polybasic acid and tris (2-hydroxyethyl) isocyanurate is used as a skeleton, the distance between crosslinking points of the resin network structure becomes long, the degree of freedom increases, flexibility is exhibited, and the processability can be improved. By thus improving the processability by using tris (2-hydroxyethyl) isocyanurate, an alkyd resin having a higher content of vegetable oil fatty acid can be used as compared with an alkyd resin used in an ink having processability so far, and the printability can be improved.

Further, the metal printing ink composition comprising an alkyd resin using tris (2-hydroxyethyl) isocyanurate has good fluidity at high temperatures, and when heated and dried after coating, the surface of the coating film is smooth, and high gloss is obtained.

In the present invention, tris (2-hydroxyethyl) isocyanurate accounts for 15 to 100 mol% of the polyol component constituting the alkyd resin. If the amount is less than 15 mol%, it is difficult to balance printability and processability, and high gloss cannot be obtained.

The polyol component other than tris (2-hydroxyethyl) isocyanurate is not particularly limited, and there may be used diols such as ethylene glycol, propylene glycol, 1, 3-butanediol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, 1, 9-nonanediol, 2-methyl-1, 8-octanediol, neopentyl glycol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, tetramethylene glycol, 1, 4-cyclohexanediol, 1, 4-cyclohexanedimethanol, hydrogenated bisphenol a, and 2-butyl-2-ethyl-1, 3-propanediol; trihydric alcohols such as glycerin, trimethylolpropane and trimethylolethane; tetrahydric alcohols such as pentaerythritol, diglycerol, ditrimethylolpropane and ditrimethylolethane have been conventionally used as polyols in alkyd resins. They may be used alone or in combination of 2 or more.

Examples of the vegetable oil fatty acid component as another component of the alkyd resin used in the present invention include linseed oil, tung oil, dehydrated castor oil, soybean oil, safflower oil, linseed oil fatty acid, tung oil fatty acid, dehydrated castor oil fatty acid, soybean oil fatty acid, safflower oil fatty acid, and the like; or unsaturated fatty acids such as oleic acid, linoleic acid, linolenic acid, eleostearic acid or ricinoleic acid. They may be used alone or in combination of 2 or more. In consideration of the price and the coating film properties, linseed oil and linseed oil fatty acids are preferred.

In addition, a part of these vegetable oils or fatty acids may be changed to a monobasic acid other than fatty acids. As other monobasic acids, benzoic acid, p-tert-butylbenzoic acid, abietic acid, hydrogenated abietic acid, and the like can be used.

Further, examples of the polybasic acid include aromatic dibasic acids such as phthalic acid (anhydride), isophthalic acid, terephthalic acid, 2, 6-naphthalenedicarboxylic acid, and 5-sodiosulfoisophthalic acid; alicyclic dibasic acids such as tetrahydrophthalic acid (anhydride), hexahydrophthalic acid (anhydride), and 1, 4-cyclohexanedicarboxylic acid; aliphatic dibasic acids such as succinic acid (anhydride), alkenylsuccinic acid (anhydride), fumaric acid, maleic acid (anhydride), itaconic acid, adipic acid, sebacic acid, azelaic acid, and norbornene diacid (anhydride); trimellitic acid (anhydride), pyromellitic acid (anhydride), methylcyclohexene tricarboxylic acid (anhydride), benzophenone tetracarboxylic acid, and the like. These polybasic acids may be used alone or in combination of 2 or more.

The alkyd resin used in the metal printing ink composition of the present invention has a vegetable oil fatty acid content of 35 to 65% by mass. If the amount is less than 35% by mass, the fluidity of the ink decreases when 15 to 100% by mole of tris (2-hydroxyethyl) isocyanurate is used as the polyol component; if the amount is more than 65% by mass, the workability and the coating film hardness are deteriorated. Considering the balance among the fluidity of the ink, the workability, and the hardness of the coating film, it is more preferably 45 to 60% by mass.

In addition, the iodine value of the alkyd resin is preferably 55-130. If less than 55, the coating film hardness becomes poor; if the amount is more than 130, the workability tends to be lowered. Considering the balance between the hardness and the workability of the coating film, it is more preferably 65 to 115.

Further, a conventionally used resin may be mixed with the alkyd resin of the present invention. That is, a known resin compatible with alkyd resins may be used alone or in combination of a plurality of resins depending on the required properties such as printability and coating film properties. Specifically, for example, a rosin-modified phenol resin, a polyester resin, a petroleum resin, an epoxy resin, a ketone resin, a rosin-modified maleic acid resin, an amino resin, a benzoguanamine resin, or the like can be exemplified.

In the oxidative polymerization curing type printing ink, a drying agent for printing ink may be added as a curing accelerator for curing the ink, if necessary, and in the present invention, a drying agent for printing ink may also be added. As the drying agent for printing ink usable in the present invention, salts of metals such as cobalt, manganese, lead, iron, and zinc with carboxylic acids such as octanoic acid, naphthenic acid, neodecanoic acid, tung oil fatty acid, linseed oil fatty acid, soybean oil fatty acid, and resin acid, that is, metal soaps, can be cited. These components may be used alone or in combination of two or more.

(pigment)

The pigment used in the present invention is not particularly limited, and known inorganic or organic pigments for printing inks may be used alone or in combination of two or more. Specifically, for example, a pigment described in patent document 2 and the like can be cited.

(Hydrocarbon solvent)

The hydrocarbon solvent used as the solvent for the metal printing ink used in the ink composition of the present invention is not particularly limited, and a hydrocarbon solvent having a boiling point range of about 200 to 400 ℃ and generally used as a solvent for a metal printing ink can be used.

As the hydrocarbon solvent, a general petroleum solvent or alkylbenzene solvent is preferably used. Examples of the petroleum solvent include solvents such as AF5, 6, and 7 of new japan petroleum (ltd.). Examples of the alkylbenzene solvent include olefin 56N, L and 200P of New Japan Petroleum chemical Co., Ltd, BAB manufactured by UIC Co., Ltd, and the like, and they may be used singly or in combination.

The amount of the hydrocarbon solvent used is not particularly limited as long as the viscosity of the ink to be printed can be adjusted to a value in the range of 5 to 40.

(other Components)

The ink composition of the present invention may contain, as other components, known pigment dispersants, waxes, stabilizers, acid catalysts, and the like, as needed.

In addition, fine powder silica, organic bentonite, or the like may be added to the ink as an auxiliary agent within a range not to impair the object of the present invention, and a gel varnish based on a metal chelate compound, a sorbitol compound, or the like may be used as a varnish component for printing ink.

The metallic printing ink composition of the present invention can be prepared by a conventional method using a roll mill, a ball mill, a bead mill, etc.

As the metal plate on which the ink composition of the present invention is printed, a metal plate such as stainless steel, aluminum, tin-plated steel plate, tin-free steel plate, or the like, or a metal base plate in which a base paint (primer) layer is provided on the metal plate is suitable, but the invention is not limited thereto. For forming the base coat layer, for example, a composition for base coat such as a color print primer (サイズ paint) or a white primer which is generally used in metal printing can be used. Further, a lamination process of the PET film may be performed.

As a method for printing the metal printing ink composition of the present invention on these metal plates, printing can be easily performed by a general printing method such as an offset printing method using dampening water, a dry offset printing method, or the like. The ink film thickness is arbitrary, and may be, for example, in the range of 0.1 to 6 μm.

The curing of the metal printing ink composition of the present invention can be carried out by using an oven which is generally used for metal printing, and heating the composition at a temperature generally in the range of 120 to 230 ℃. The heating time may be any value as long as it is 3 minutes or more, and is usually within a range of 3 minutes to 30 minutes.

The printed metal sheet of the present invention thus obtained does not necessarily need to be coated with a varnish for glossing (オーバープリント), but by using the varnish for glossing, more favorable coating film properties can be obtained.

When the varnish for glossing is applied to the metal printing ink printed layer of the printed metal plate of the present invention, it is usually preferable to heat-cure the metal printing ink composition of the present invention, but it is also possible to heat-cure both of them after repeating application by a wet-on-wet (ウェットオンウェット) method.

The metallic printing ink composition of the present invention has excellent printability and can form a high-gloss and high-processability ink coating film on a metal plate, and thus can be suitably used as a metallic printing ink for a sheet.

Examples

The present invention will be described below based on synthesis examples, and the like, but the present invention is not limited to these examples. In each example, parts and% are based on mass.

Synthesis example 1

A liquid alkyd resin (1) was obtained by charging 45 parts of linseed oil fatty acid, 25.4 parts of phthalic anhydride, 26.3 parts of THEIC, and 9.3 parts of glycerin into a reaction apparatus equipped with a stirrer, a water separator, a condenser, a nitrogen inlet tube, and a thermometer, reacting at 220 to 230 ℃ while refluxing xylenol (キシロール) in the presence of nitrogen gas until the acid value was 10 or less, and then distilling and separating the xylenol. The dehydration amount was 6.0 parts. The iodine value of the resin (1) was 86 (the iodine value was measured in accordance with JIS K0070, the same shall apply hereinafter).

Synthesis example 2

50 parts of linseed oil fatty acid, 20.9 parts of phthalic anhydride, 23.0 parts of THEIC, and 11.8 parts of trimethylolpropane were charged into the same reaction apparatus as in Synthesis example 1, and reacted at 220 ℃ to 230 ℃ while refluxing xylenol in the presence of nitrogen gas until the acid value was 10 or less, and then the xylenol was separated by distillation to obtain a liquid alkyd resin (2). The dehydration amount was 5.7 parts. Further, the iodine value of the resin (2) was 93.

Synthesis example 3

50 parts of linseed oil fatty acid, 21.1 parts of isophthalic acid, 32.4 parts of THEIC, and 4.2 parts of pentaerythritol were charged into the same reaction apparatus as in Synthesis example 1, and reacted at 220 to 230 ℃ while refluxing xylenol in the presence of nitrogen gas until the acid value was 10 or less, and then the xylenol was separated by distillation to obtain a liquid alkyd resin (3). The dehydration amount was 7.7 parts. Further, the iodine value of the resin (3) was 95.

Synthesis example 4

40 parts of dehydrated castor oil fatty acid, 25.6 parts of phthalic anhydride, 26.5 parts of THEIC, and 13.6 parts of trimethylolpropane are charged into the same reaction apparatus as in Synthesis example 1, and reacted at 220 to 230 ℃ in the presence of nitrogen while refluxing xylenol until the acid value is 10 or less, and then xylenol is separated by distillation to obtain a liquid alkyd resin (4). The dehydration amount was 5.7 parts. Further, the iodine value of the resin (4) was 60.

Synthesis example 5

Into the same reaction apparatus as in synthesis example 1, 45 parts of linseed oil fatty acid, 30.7 parts of isophthalic acid, 11.1 parts of THEIC, and 22.7 parts of trimethylolpropane were charged, and in the presence of nitrogen, xylenol was reacted at 220 to 230 ℃ while being refluxed until the acid value became less than 10, and then xylenol was separated by distillation to obtain a liquid alkyd resin (5). The dehydration amount was 9.5 parts. Further, the iodine value of the resin (5) was 87.

Synthesis example 6

55 parts of linseed oil fatty acid, 14.6 parts of isophthalic acid and 37.1 parts of THEIC were put into the same reaction apparatus as in Synthesis example 1, and reacted at 220 to 230 ℃ in the presence of nitrogen gas while refluxing xylenol until the acid value was 10 or less, followed by distillation to separate xylenol, thereby obtaining a liquid alkyd resin (6). The dehydration amount was 6.7 parts. Further, the iodine value of the resin (6) was 106.

Synthesis example 7

30 parts of linseed oil fatty acid, 30.0 parts of phthalic anhydride, 30.1 parts of THEIC, and 15.4 parts of trimethylolpropane were charged into the same reaction apparatus as in Synthesis example 1, and reacted at 220 ℃ to 230 ℃ while refluxing xylenol in the presence of nitrogen gas until the acid value was 10 or less, and then the xylenol was separated by distillation to obtain a liquid alkyd resin (7). The dehydration amount was 5.5 parts. Further, the iodine value of the resin (7) was 56.

Synthesis example 8

70 parts of dehydrated castor oil fatty acid, 6.5 parts of phthalic anhydride, 23.6 parts of THEIC, and 5.2 parts of trimethylolpropane are charged into the same reaction apparatus as in Synthesis example 1, and reacted at 220 to 230 ℃ while refluxing xylenol in the presence of nitrogen gas until the acid value is 10 or less, and then the xylenol is separated by distillation to obtain a liquid alkyd resin (8). The dehydration amount was 5.3 parts. Further, the iodine value of the resin (8) was 110.

Synthesis example 9

40 parts of linseed oil fatty acid, 31.9 parts of phthalic anhydride, and 34.5 parts of trimethylolpropane were charged into the same reaction apparatus as in Synthesis example 1, and reacted at 220 to 230 ℃ in the presence of nitrogen gas while refluxing xylenol until the acid value was 10 or less, and then xylenol was separated by distillation to obtain a liquid alkyd resin (9). The dehydration amount was 6.4 parts. Further, the iodine value of the resin (9) was 75.

Synthesis example 10

Into the same reaction apparatus as in synthesis example 1, 60 parts of linseed oil fatty acid, 21.8 parts of isophthalic acid, 4.8 parts of THEIC, and 22.0 parts of trimethylolpropane were charged, and in the presence of nitrogen, xylenol was reacted at 220 to 230 ℃ while being refluxed until the acid value became less than 10, and then xylenol was separated by distillation to obtain a liquid alkyd resin (10). The dehydration amount was 8.6 parts. Further, the iodine value of the resin (10) was 115.

The compositions and properties of the alkyd resins obtained in Synthesis examples 1 to 10, respectively, are shown in Table 1.

[ Table 1]

Example 1

15 parts of Raonol blue FG-7351 (manufactured by Toyo ink Co., Ltd.) as a pigment, 60 parts of alkyd resin (1), 1 part of manganese naphthenate, and 25 parts of alkylbenzene (BAB manufactured by UIC) as a hydrocarbon solvent were ground by a three-roll grinder to obtain a blue ink (1).

The obtained blue ink (1) was printed on a metal plate, and the curability, gloss, processability and printability were evaluated by the following methods. The results are shown in Table 2.

Curability test

0.3mL of ink was printed on a tin-plated steel plate (tin-plated plate, ブリキ plate) by using a RI Tester (manufactured by Zyohima corporation) 2 split roll (2 split ロール), and the resulting printed plate was heated at 150 ℃ for 10 minutes in an electric oven. After the heating and drying, the plate temperature was cooled to room temperature, and the pencil hardness of the printed surface was measured in accordance with JIS K5400.

Evaluation criteria

O: on the ink surface of the printing plate, no scratch was generated with an HB pencil.

And (delta): on the ink surface of the printing plate, although scratch was generated by HB, no scratch was generated by B.

X: on the ink side of the printing plate, scratches are generated with B.

Gloss evaluation

The sharpness (writability) of the image on the ink surface of the printing plate heat-cured in the above-described curing test, that is, the brightness of the image projected on the ink surface by a fluorescent lamp was visually observed.

Evaluation criteria

O: the fluorescent lamp has a sharp image.

And (delta): fluorescent light images, etc.

X: the fluorescent lamp image is not sharp.

Workability test

The clear coating material for metal sheets manufactured by Toyo ink manufacturing Co., Ltd was applied to the printing plate manufactured in the above-mentioned curing test so that the amount of the applied coating film was 60mg/100cm²The curing was carried out by heating at 160 ℃ for 10 minutes using an electric oven. At room temperature, theThe printed coated plate was processed into an angular can (depth 20mm, diameter of each corner portion 4mm, 6mm, 8mm, 10mm) by a press, and each corner portion was visually observed.

Evaluation criteria

O: no peeling of the coating film was observed.

X: peeling of the coating film was found.

Printability test

The ink was collected on a rubber roller for testing by a high-speed printability tester (PM 904PT manufactured by SMT, Ltd.), printed on an tin-plated steel sheet from the rubber roller while moving the tin-plated steel sheet at a speed of 2m/s with the ink coating thickness being 1 μm, and the ink was cured by heating, and then the transfer state of the ink was observed. The ink coating film was evaluated as good in rolling (cut-off し) and smooth in buffing (shiwa り), as good as o, as medium as Δ, and as poor in rolling pressure, as good as x.

Examples 2 to 6 and comparative examples 1 to 4

Inks (2) to (10) were prepared in the same manner as in example 1 except that the resins (2) to (10) synthesized in synthesis examples 2 to 10, respectively, were used as alkyd resins in the mixing ratios shown in table 2, and the properties were evaluated. The results are shown in Table 2.

[ Table 2]

As is clear from table 2, the metal printing ink using the alkyd resin in which tris (2-hydroxyethyl) isocyanurate is used in a part or all of the polyol component and the content of the vegetable oil fatty acid is in a specific range can achieve both printability and processability, which have not been achieved so far, and can exhibit high gloss.

Claims (3)

1. A metal printing ink composition comprising a pigment, an alkyd resin and a hydrocarbon solvent, wherein the proportion of vegetable oil fatty acid constituting the alkyd resin is 35 to 65% by mass, and 15 to 100 mol% of the polyol component is tris (2-hydroxyethyl) isocyanurate.

2. The metal printing ink composition of claim 1, wherein the alkyd resin has an iodine number of 55 to 130.

3. A printed metal plate having an ink layer formed using the metal printing ink composition according to claim 1 or 2 on a metal plate or a metal substrate plate having a base coat layer provided on the metal plate.