JPH0748534A - Coating composition - Google Patents

Abstract

PURPOSE:To provide the composition which, when used as a finishing varnish, applied on the aluminum-containing metallic ink, and subjected to retorting, does not cause the discoloration of the thermosetting and UV-curing silver ink. CONSTITUTION:The material is one applied on a metallic ink and containing at least one film cure assistant selected from among a phosphoric acid catalyst, an amine-blocked phosphoric acid catalyst, a phosphate, an amine-blocked phosphate, a phosphite and an amine-blocked phosphite.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a can coating external coating,
Particularly, it relates to a coating having excellent retort resistance. More specifically, it relates to finishing varnishes used on metal inks.

[0002]

2. Description of the Related Art A metal can made of tin, steel, aluminum or the like is coated with a resin film by coating or laminating on the inner surface for rust prevention and food protection, and on the outer surface it is rustproof. Painting and printing are performed to improve the display and design of products. For example, on the outer surface of a metal can, for example, white coating or a film is laminated on a metal plate directly or through an undercoat, characters and patterns are printed, and then a finishing varnish is applied. Recently, the consumption of coffee cans and oolong tea cans has increased, and the can design of metallic cans has increased. In order to give a metallic feel, it is common to use a metal ink containing aluminum powder (hereinafter referred to as silver ink).

As the silver ink, a thermosetting ink or a UV curable ink is used, but the UV curable ink is increasingly used in terms of work efficiency. Coffee cans and oolong tea cans are subjected to retort treatment using high temperature and high pressure steam for sterilization.
Conventionally, a sulfonic acid-based catalyst has been used as a curing aid in the finishing varnish of a paint for can making. However, when a sulfonic acid-based catalyst is used as a curing aid, when combined with silver ink, the silver ink in the part where steam directly hits the can discolors during retort processing, which may significantly reduce the commercial value of the can. there were.

[0004]

It is an object of the present invention to provide a paint which does not cause discoloration of thermosetting and UV curable silver inks even when a finishing varnish is coated on silver ink and subjected to retort treatment.

[0005]

A first aspect of the present invention relates to a coating material applied on a metal ink, which comprises a phosphoric acid catalyst, an amine-blocked phosphoric acid catalyst, a phosphoric acid ester, an amine-blocked phosphoric acid ester, a phosphorous acid ester and an amine block. It is a coating material containing at least one kind of coating film curing aid selected from phosphite ester. A second invention is a coating material applied on a metal ink, which comprises an amino resin as a curing component of a coating film-forming resin of the coating material, wherein the amino resin is a phosphoric acid catalyst, an amine-blocked phosphoric acid catalyst, a phosphoric acid ester, an amine. At least one selected from a blocked phosphoric acid ester, a phosphorous acid ester, and an amine blocked phosphorous acid ester.
It is a paint characterized by using one synthesized by using one kind of catalyst.

A third aspect of the present invention is a coating material applied on a metal ink, which comprises an amino resin as a curing component of a coating film-forming resin of the coating material, and 33 parts of the reactive portion of the amino resin.
% Or more is an ether- or ester-modified amino resin, and is at least selected from phosphoric acid catalysts, amine-blocked phosphoric acid catalysts, phosphoric acid esters, amine-blocked phosphoric acid esters, phosphorous acid esters, amine-blocked phosphorous acid esters. It is a paint characterized by using one type of curing aid together. The metallic ink of the present invention means an ink containing aluminum powder in order to give a metallic feeling.

Examples of the phosphoric acid catalyst used in the present invention include pyrophosphoric acid, phosphoric acid, metaphosphoric acid and phosphorous acid. As the phosphoric acid ester, for example, those having the following structures can be used. (In the above formula, R ₁ , R ₂ , and R ₃ represent a hydrocarbon group such as an alkyl group and an arylene group.) As the phosphite, for example, those having the following structures can be used.

[0008] (In the above formula, R ₁ , R ₂ and R ₃ represent a hydrocarbon group such as an alkyl group and an arylene group.) Amine-blocked phosphoric acid ester is a phosphoric acid ester having the above structure and an amine such as ammonia, diethylamine or morpholine. It is a neutralized product by adding a class of compounds and has an acid value of 3 to 20. It

The amino resin used in the second invention is synthesized by using the above phosphoric acid catalyst as a catalyst for the amino resin. A low molecular weight alcohol such as methyl alcohol, methyl alcohol, isobutyl alcohol, butyl alcohol or formalin is used for modification of the amino resin used in the third invention, and 33% or more of the functional part of the amino resin is modified. Is desirable. The amount of the curing aid added is in the range of 0.005 to 5% by weight, preferably 0.01 to 1% by weight, and more preferably 0.01 to 5% by weight based on the total amount of the solid content of the active ingredient of the curing aid. 0.5
Used in the range of.

The proportion of the amino resin used in the second and third inventions is 5% to 95% (in the coating solid content), preferably 30% to 70% (in the coating solid content). .
In the first invention, any amino resin can be used regardless of the type of amino resin synthesis catalyst. The form of the coating material used in the present invention may be a solvent type coating material, a water-soluble coating material, a water dispersion type coating material, a radiation curing type coating material and the like. As the film-forming resin used in the present invention, a resin of that kind used in a paint for cans can be used without any special limitation. For example, epoxy / amino type, epoxy ester / amino type, epoxy ester /
Any type of resin such as acrylic / amino type, acrylic / amino type, polyester / amino type, alkyd / amino type can be used.

The amino resin is a melamine resin,
Melamine / benzoguanamine co-condensation resin, benzoguanamine resin, urea resin, glycoluril resin may be used alone or in combination. The coating material used in the present invention is composed of at least a film-forming resin, a curing catalyst and a solvent, but the amino resin in the film-forming resin of the present invention is synthesized by using a phosphoric acid-based synthetic catalyst. In the case of the above, the curing catalyst may be omitted. As the solvent, solvents such as aromatic solvents, aliphatic solvents, alcohol solvents, ketone solvents, ester solvents, ether solvents, and water that have been conventionally used for paints are used. The coating material produced for this purpose may further contain an auxiliary agent such as a lubricant, an antifoaming agent, an anti-flushing agent, a plasticizer and an anti-ultraviolet agent, and it is necessary to use it as a colored coating material by coloring it. In some cases, a colorant that can be used in the paint is used together.

[0012]

EXAMPLES The present invention will be described in more detail based on examples. In the examples, "%" and "parts" mean "% by weight" and "parts by weight", respectively. Example 1 A 1 L four-necked flask equipped with a nitrogen inlet tube, a thermometer, a separator, a condenser, and a stirrer was used for Epicoat 1
004 (Epoxy resin manufactured by Yuka Shell Epoxy Co., Ltd.) 280
And 120 parts of dehydrated castor oil fatty acid were charged, the temperature was raised to 230 ° C., and the esterification reaction was carried out under reflux of xylene. 192 parts of this product butyl cellosolve, Solvesso 100 1
It was diluted with 92 parts to obtain an epoxy ester resin solution having a nonvolatile content of 49.5% and an acid value of 3.0. A melamine / benzoguanamine = 30/70 synthesized using formic acid as a synthesis catalyst and a melamine / benzoguanamine co-condensation amino resin having an etherification rate of 33% were added to this solution at a ratio of 50/50 (solid content ratio), and applied. A film-forming resin solution was used.

Phosphoric acid was mixed with the above-mentioned coating film forming resin solution in an amount of 0.05% with respect to the solid content of the coating film forming resin solution and diluted with butyl cellosolve / solvesso 100 = 50/50 to prepare a coating material. Example 2 Catalyst 296-9 (phosphoric acid ester, manufactured by Mitsui Toatsu Chemicals, Inc.) was added to the coating film forming resin solution used in Example 1 based on the solid content of the coating film forming resin solution.
0.1% of 9 active ingredients were mixed and diluted with butyl cellosolve / Solvesso 100 = 50/50 to prepare a paint.

Example 3 Epicoat 1 was applied to a 1 L four-necked flask equipped with a nitrogen inlet tube, a thermometer, a separator, a condenser, and a stirrer.
004 (Epoxy resin manufactured by Yuka Shell Epoxy Co., Ltd.) 280
And 120 parts of dehydrated castor oil fatty acid were charged, the temperature was raised to 230 ° C., and the esterification reaction was carried out under reflux of xylene. 192 parts of butyl cellosolve, Solvesso 100
Diluted with 192 parts, nonvolatile content 49.5%, acid value 3.0
To obtain an epoxy ester resin solution. Melamine / benzoguanamine = 20/80 synthesized by using formic acid as a synthesis catalyst in this solution, and melamine / etherification rate of 100% /
The benzoguanamine co-condensation type amino resin was blended at a ratio of 50/50 (solid content ratio) to obtain a coating film forming resin solution.

The above coating film forming resin solution was mixed with Nacure.
4167 (manufactured by KING, amine block product of phosphoric acid ester) was mixed with the solid content of the film-forming resin solution in an amount of 0.5% as an active ingredient, and butyl cellosolve / solveso 10 was added.
The paint was prepared by diluting with 0 = 50/50. Example 4 Epicoat 1 was placed on a 1 L four-necked flask equipped with a nitrogen inlet tube, a thermometer, a separator, a condenser, and a stirrer.
004 (Epoxy resin manufactured by Yuka Shell Epoxy Co., Ltd.) 280
And 120 parts of dehydrated castor oil fatty acid were charged, the temperature was raised to 230 ° C., and the esterification reaction was carried out under reflux of xylene. 192 parts of butyl cellosolve, Solvesso 100
Diluted with 192 parts, nonvolatile content 49.5%, acid value 3.0
To obtain an epoxy ester resin solution. A benzoguanamine resin having an etherification rate of 80%, which was synthesized using phosphoric acid as a catalyst at the time of synthesis, was added to this solution at a ratio of 50/50 (solid content ratio) to obtain a film forming resin solution. The coating film-forming resin solution was replaced with butyl cellosolve / solvesso 100 = 50/5.
The paint was adjusted by diluting with 0.

Example 5 Epicoat 1 was placed on a 1 L four-necked flask equipped with a nitrogen inlet tube, a thermometer, a separator, a condenser, and a stirrer.
004 (Epoxy resin manufactured by Yuka Shell Epoxy Co., Ltd.) 280
And 120 parts of dehydrated castor oil fatty acid were charged, the temperature was raised to 230 ° C., and the esterification reaction was carried out under reflux of xylene. 192 parts of butyl cellosolve, Solvesso 100
Diluted with 192 parts, nonvolatile content 49.5%, acid value 3.0
To obtain an epoxy ester resin solution. A benzoguanamine resin having an etherification rate of 80%, which was synthesized using phosphoric acid as a catalyst at the time of synthesis, was added to this solution at a ratio of 50/50 (solid content ratio) to obtain a film forming resin solution.

Catalyst 296-9 (manufactured by Mitsui Toatsu Chemicals, Inc., phosphoric acid ester) was mixed with the above-mentioned coating film forming resin solution in an amount of 0.1% as an active ingredient based on the solid content of the coating film forming resin solution. , Butyl Cellosolve / Solvesso 100 = 50/5
The paint was adjusted by diluting with 0. Comparative Example 1 A coating material was prepared in the same manner as in Example 1 except that paratoluenesulfonic acid was used instead of phosphoric acid as shown in Table 2. Comparative Example 2 Catalyst 296-9 in Example 2
Instead of Nacure155 (KING, Din
onylnaphthalen Disulfonic
The coating material was prepared in the same manner except that Acid) was used as shown in Table 2.

Comparative Example 3 Na in place of Nacure 4167 in Example 3 was replaced by Na.
cure 5225 (KING, Dodecylbe
A paint was prepared in the same manner except that nzen Sulfonic Acid amine block product) was used as shown in Table 2. Comparative Example 4 A coating material was prepared in the same manner as in Example 4 except that formic acid was used as the benzoguanamine resin synthesis catalyst instead of phosphoric acid. COMPARATIVE EXAMPLE 5 In Example 5, formic acid was used as a catalyst for benzoguanamine resin synthesis instead of phosphoric acid, and Catalyst 296-
9105 instead of 9 (made by KING, D
inonylnaphthalene (Mono) Su
lfonic Acid) was used as shown in Table 2 to prepare a coating material in the same manner.

The formulations shown in Tables 1 and 2 represent parts by weight, and the viscosity is 25 ° C. 4 It is a value measured by Ford cup. In Table 1 and Table 2, amino resin 1 is melamine / benzoguanamine = 30.
/ 70, the etherification rate is 33%, the amino resin 2 is melamine /
Benzoguanamine = 20/80, etherification rate 100
%, An amino resin synthesized by using formic acid as a synthetic catalyst, an amino resin 3 is a benzoguanamine resin having an etherification rate of 100% using phosphoric acid as a synthetic catalyst, and an amino resin 4 is an etherification rate using formic acid as a synthetic catalyst. 100%
Benzoguanamine resin of Further, the curing aid represents the weight% of the active ingredient of the curing aid with respect to the solid content.

Tin-free steel plate size (under
-Coat) layer, dried epoxy / pheno type paint
Coating amount 25mg / 100cm²Painted with a test coater
And heated and dried at 210 ° C. for 10 minutes. Next, thermosetting
Solid-print lithographic silver ink for metal plate, 150 ℃ -10 minutes
Heat-dried product, and planographic silver for thermosetting metal plate
UV-curable lithographic silver ink for metal plate instead of ink
Solid print, 160W x 1 light x 55m / min, UV light
Two types of coated silver ink plates were prepared. . Then on
The finished varnishes obtained in the Examples and Comparative Examples were dried and coated.
80 mg / 100 cm ²Paint with a test coater so that
A test piece was obtained by heating and drying at 165 ° C for 10 minutes.

Table 3 shows the test results of the discoloration resistance and other physical properties of the coating film thus obtained. In the table, ⊚ indicates excellent, ∘ indicates good, Δ indicates slightly defective, and × indicates defective. Each test method is as follows. Discoloration resistance Test piece cut into 10 cm x 14 cm and stuck to a 250 ml commercial can was inserted into a container made to resemble a container for transporting cans during continuous retort, and set in a predetermined position in a retort kettle. After the retort treatment at -20 ° C for 20 minutes, the degree of discoloration of the silver ink is visually evaluated.

Impact resistance Using a DuPont impact tester and 1/2 inch wick in an atmosphere of 25 ° C., a 500 g load was dropped from a height of 50 cm to apply an impact, and then a retort treatment was performed at 130 ° C. for 30 minutes. , Visually evaluate the degree of damage to the coating film. Retort resistance The test piece was put in a retort kettle and subjected to retort treatment at 130 ° C. for 30 minutes, and the damage of the coating film was visually evaluated. Pencil hardness The hardness of the coating film was examined using Mitsubishi Uni in an atmosphere of 25 ° C. Scratch value A sapphire needle (r = 125μ) was attached to the cross-cut tester, and evaluation was performed with the maximum load at which the coating film was not scratched.

As is clear from the test results shown in Table 3,
All of the present invention have better discoloration resistance of the silver ink than the comparative example, and in other test items, all of the present invention have performance equal to or higher than that of the comparative example.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

[Table 3]

[0027]

EFFECTS OF THE INVENTION A can using silver ink prepared by using the coating composition of the present invention does not cause discoloration of the silver ink even when subjected to retort treatment, and thus a can having a high commercial value can be obtained. Was completed.

Claims (3)

[Claims] 1. At least one selected from a phosphoric acid catalyst, an amine-blocked phosphoric acid catalyst, a phosphoric acid ester, an amine-blocked phosphoric acid ester, a phosphorous acid ester, and an amine-blocked phosphorous acid ester in a coating material applied on a metal ink. A coating material containing one type of coating film curing aid. 2. A paint applied on a metal ink, which contains an amino resin as a curing component of a coating film-forming resin of the paint, wherein the amino resin is a phosphoric acid catalyst, an amine-blocked phosphoric acid catalyst, a phosphoric ester, an amine block. A paint characterized by using one synthesized using at least one catalyst selected from a phosphorylated phosphoric acid ester, a phosphorous acid ester, and an amine-blocked phosphorous acid ester. 3. A paint applied on a metal ink, which contains an amino resin as a curing component of a coating film-forming resin of the paint, and 33% or more of the reactive portion of the amino resin is ether- or ester-modified. Is an amino resin, and at least one curing aid selected from phosphoric acid catalysts, amine-blocked phosphoric acid catalysts, phosphoric acid esters, amine-blocked phosphoric acid esters, phosphorous acid esters, amine-blocked phosphorous acid esters is used in combination. Paint that is characterized.