JPH07278487A - Water-based coating composition for drawn can coated with polyester film - Google Patents

Abstract

PURPOSE:To obtain a water-based coating composition which gives a coating excellent in adherence to a polyester film, suitability for retortion, scratch resistance, processability, and gloss. CONSTITUTION:This coating composition comprises a resin mixture comprising an aqueous acrylic resin as the main ingredient and an aqueous amino resin as a hardener therefor, an amine-blocked acid catalyst having a dissociation temp. of 45-65 deg.C, and at least one of an amine-blocked acid catalyst having a dissociation temp. of 100-120 deg.C, an amine-blocked acid catalyst having a dissociation temp. of 120-140 deg.C, and an amine-blocked acid catalyst having a dissociation temp. of 150-170 deg.C, the amount of each acid catalyst being 0.05-2 pts. in terms of the amount of the active ingredient per 100 pts. the solid resins.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester film-coated water-based coating composition for a squeezer, and more specifically, it has excellent adhesion to a polyester film and at the same time has retort resistance, scratch resistance, processability and glossiness. The present invention relates to an excellent polyester film-coated water-based coating composition for a squeezer.

[0002]

2. Description of the Related Art Among food cans and beverage cans for storing foods, soft drinks, etc., of two-piece cans composed of two parts, a can body / can bottom and a can lid, which are integrally formed, In this case, aluminum or steel is used as the material, as typified by DI cans produced by drawing and ironing, the inner surface is painted from the viewpoint of content retention, and the outer surface is a decorative product with an external appearance. Base coat (or size coat), printing ink and top coat are applied for the purpose of giving value.

In recent years, as the global environmental problems have been exclaimed, the development of a pollution-free production system for the can manufacturing process has progressed, and a polyester film coating with reduced internal and external coating as a new can container pursuing environmental protection, resource saving and energy saving. A tin can has been devised. Conventionally, in the can making process of a two-piece can such as a DI can, after a metal material is subjected to DI processing and trimming to form an original container, first, a base coat (or size coat) is applied from the outer surface side, Printing ink and a top coat are applied on it. Next, after the outer surface side is finished, the inner surface side is painted to be a can body that can be provided to the content filling step through necking processing and flange processing.

On the other hand, the newly conceived polyester film coated squeeze can is obtained by laminating a polyester film on both sides of a coiled metal material, squeezing it into a container, and then printing ink and top coat on the outer surface side. Is painted and finally necked and flanged in the same way as DI cans. Therefore, when the two are compared, in the polyester film-coated squeeze can, the polyester film attached to the inner and outer surfaces thereof corresponds to the inner surface coating and the outer surface base coat coating in the DI can, so that only the outer top coat is used as the coating process. Become.
The present invention relates to an aqueous coating composition for a polyester film-coated squeezer in a top coat, which is applied only to a polyester film-coated squeezer.

As can be seen from the difference in the above can manufacturing process,
As a matter of course, the baking conditions when the top coat in the DI can and the top coat in the polyester film-coated squeeze can are applied are different. In the case of DI cans, after the top coat itself is baked, the baking at the time of inner surface coating is added as additional baking. Therefore, a sufficient amount of heat is applied in total for baking, and since the baking is performed twice, the coating film is toughened by the second baking even if the first baking is relatively gentle. This is a very advantageous baking condition because a coating film with an efficient crosslinking reaction is formed and distortion of the coating film is relaxed.

On the other hand, in the case of a polyester film-coated squeeze can, the baking required to form a tough coating film as in the case of a DI can must be achieved with a single amount of heat. However, with the streamlining of the can manufacturing process, the baking conditions are being reduced more and more, and since it is necessary to maintain the performance of the polyester film, the baking is performed at a temperature at least below the melting point of the polyester film and in a short time. Must be done.

In general, water-based paints for DI cans contain polyester / polyester as a main component for imparting a tough and moderately flexible coating film.
Amino resins or acrylic / amino resins are used, but recently acrylic / amino resins have become the mainstream because of their excellent water resistance, and acid catalysts are usually mixed as a curing aid. There is. Here, if a water-based paint for DI cans that does not give a tough coating film when a sufficient amount of heat is applied twice is used as it is for polyester film-coated squeezing cans, the curing will be insufficient and the coating film hardness will be low. The physical properties such as adhesion to the polyester film, retort resistance, scratch resistance, and processability could not be satisfied.

Next, trying to adapt the water-based paint for DI cans to the baking conditions of polyester film coated squeezer can specifications,
We aim to improve resin curability by changing the coating composition ratio such as increasing the amount of amino resin which is a curing agent and / or increasing the amount of acid catalyst.
Attempts were made to divert the water-based paint for DI cans to polyester film-coated squeezed cans, but in all cases the curing strain increased and adhesion to the polyester film decreased, and retort resistance, scratch resistance, processability and gloss However, there was a problem such as a decrease in the value, and it was not successful.

[0009]

DISCLOSURE OF THE INVENTION As a result of intensive studies conducted by the present inventors in view of the above-mentioned present situation, as a result, several kinds of block-type acid catalysts which are stepwise adjusted to a predetermined dissociation temperature are added to an acrylic / amino resin. By using together, it was found that the adhesiveness to the polyester film is excellent, and at the same time, the retort resistance, the scratch resistance, the processability and the glossiness are excellent, which led to the invention of the polyester film-coated water-based coating composition for a squeezer. .

[0010]

That is, according to the present invention, based on 100 parts of solid content of a resin composition using an aqueous acrylic resin as a main component and an aqueous amino resin as a curing agent for the same,
0.05 to 2 parts of an amine block type acid catalyst adjusted to a dissociation temperature of 45 to 65 ° C. as an active ingredient, and a dissociation temperature of 100 to
The amine block type acid catalyst adjusted to 120 ° C. is used as an active ingredient in an amount of 0.05 to 2 parts and / or a dissociation temperature of 120 to
The amine block type acid catalyst adjusted to 140 ° C. is used as an active ingredient in an amount of 0.05 to 2 parts and / or a dissociation temperature of 150 to
A polyester film-coated water-based paint composition for a squeezer, which comprises using an amine-blocked acid catalyst adjusted to 170 ° C. as an active ingredient in an amount of 0.05 to 2 parts.

Dissociation temperature used in the present invention is 45 to 65 ° C.
Examples of the amine block type acid catalyst adjusted to include sulfonic acids such as sulfonic acid, methanesulfonic acid, P-toluenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid and dinonylnaphthalenedisulfonic acid, or phosphoric acid, Phosphoric acid such as phosphoric acid methyl ester and phosphoric acid ethyl ester is used as a volatile blocking agent having a boiling point near a predetermined dissociation temperature as tert-butylamine, propylamine, allylamine, diethylamine,
It is obtained by mixing and neutralizing with an organic amine such as sec-butylamine and isobutylamine.

Dissociation temperature used in the present invention 100 to 12
Examples of amine block type acid catalysts adjusted to 0 ° C. include sulfonic acids such as sulfonic acid, methanesulfonic acid, P-toluenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, dinonylnaphthalenedisulfonic acid, and phosphorus. Acid, phosphoric acid methyl ester, phosphoric acid such as phosphoric acid ethyl ester, pentylamine as a volatile blocking agent having a boiling point near a predetermined dissociation temperature,
It is obtained by mixing and neutralizing with an organic amine such as piperidine, dipropylamine, pyridine, N-methylmorpholine, ethylenediamine and propylenediamine.

Dissociation temperatures used in the present invention 120-14
Examples of amine block type acid catalysts adjusted to 0 ° C. include sulfonic acids such as sulfonic acid, methanesulfonic acid, P-toluenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, dinonylnaphthalenedisulfonic acid, and phosphorus. Phosphoric acids such as acid, phosphoric acid methyl ester, and phosphoric acid ethyl ester are used as volatile blocking agents having a boiling point near a predetermined dissociation temperature, such as morpholine and α-.
Picoline, pyrrole, 2- (dimethylamino) ethanol, cyclohexylamine, diisobutylamine, N-
It is obtained by mixing and neutralizing with an organic amine such as ethylmorpholine.

Dissociation temperature used in the present invention 150 to 17
Examples of amine block type acid catalysts adjusted to 0 ° C. include sulfonic acids such as sulfonic acid, methanesulfonic acid, P-toluenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, dinonylnaphthalenedisulfonic acid, and phosphorus. 2,4-lutidine, dibutylamine, 2- (diethylamino) ethanol, 2-ethylhexylamine as a volatile blocking agent having a boiling point near a predetermined dissociation temperature, such as acids, phosphoric acid methyl ester, and phosphoric acid ethyl ester. It is obtained by mixing and neutralizing with an organic amine such as 2-aminoethanol.

The aqueous coating composition for polyester cans coated with a polyester film according to the present invention comprises an amine block type acid catalyst adjusted to a dissociation temperature of 45 to 65 ° C. and a dissociation temperature of 100 to 1
It is achieved only by using a single or two or more kinds of catalysts appropriately selected and combined from amine block type acid catalysts adjusted to 20 ° C, 120 to 140 ° C and 150 to 170 ° C. It goes without saying that the blending amount should be appropriately adjusted by these combinations, and if either one is missing or falls outside the above-mentioned suitable blending range, the required performance cannot be satisfied, and the polyester The physical properties such as the adhesion to the film, the retort resistance, the scratch resistance, the processability and the gloss are adversely affected.

For example, when the amine block type acid catalyst adjusted to the dissociation temperature of 45 to 65 ° C. is not contained, the initial curing property is deteriorated and satisfactory retort resistance and glossiness are not obtained, and the above-mentioned suitable compounding ratio is obtained. When it is less than the range, the same thing occurs, and when it is more than the range, the adhesion to the polyester film, processability, retort resistance and gloss are not satisfied. Dissociation temperature 100-120 ° C, 120-1
When it does not contain a single or two or more kinds of catalysts appropriately selected and combined from the amine block type acid catalysts adjusted to 40 ° C. and 150 to 170 ° C., the adhesion to the polyester film and the scratch resistance decrease, and The same thing occurs when the amount is less than the appropriate compounding range described above, and conversely, when the amount is more than the above range, the retort resistance and gloss are not satisfied.

The aqueous acrylic resin used in the present invention includes α / β monoethylenically unsaturated carboxylic acid,
It is a copolymer of hydroxyalkyl acrylate or methacrylate and a vinyl monomer copolymerizable with the above-mentioned monomers, which is dissolved or dispersed in water with a basic substance. Examples of the α / β monoethylenically unsaturated carboxylic acid include, but are not limited to, acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, and itaconic acid. These α
The β-monoethylenically unsaturated carboxylic acid can be used alone or as a mixture of two or more kinds.

Examples of the hydroxyalkyl acrylate or methacrylate include hydroxymethyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyamyl acrylate, hydroxyhexyl acrylate and the corresponding methacrylates, but not limited thereto. Absent. These hydroxyalkyl acrylates or methacrylates can be used alone or as a mixture of two or more kinds. Vinyl monomers copolymerizable with the above monomers include ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, stearyl methacrylate, cyclohexyl methacrylate and the like. Alkyl ester of acrylic acid or methacrylic acid, aromatic vinyl compound such as styrene, vinyltoluene, α-methylstyrene, vinyl acetate, vinyl ethyl ether, acrylamide, N-methylol acrylamide, N
-Methylol methacrylamide, N-methoxymethyl acrylamide, N-ethoxymethyl acrylamide, N
-N-alkoxyalkyl-substituted amides such as butoxymethylacrylamide and N-isobutoxymethylacrylamide, or alkylaminomethacrylates such as N, N-dimethylethylaminomethacrylate and N, N-diethylethylaminomethacrylate, or glycidylmethacrylate. It may be mentioned by way of example and not limitation. These vinyl monomers can be appropriately selected and used as one kind or a mixture of two or more kinds according to the physical properties of the coating film to be obtained.

The above-described vinyl monomer is radically polymerized into a resin by a conventional method. That is, in the presence of a peroxide radical polymerization initiator, an azo radical polymerization initiator, etc., radicals are generated by dropwise addition of a reducing agent while heating little by little, and the resinification reaction proceeds. The polymerization conditions are not particularly limited, but the polymerization temperature is usually 50 to 120 ° C., and the polymerization initiator is added by about 0.1 to 10% by weight with respect to the entire vinyl monomer.
The time required for resinification is usually 3 to 5 depending on the reaction temperature.
It's about time. Further, in the resinification reaction, an organic solvent can be used in combination for adjusting viscosity, controlling reaction and the like. After completion of the resinification reaction, if necessary, the organic solvent is removed under reduced pressure heating to dissolve or disperse the basic substance in water. The basic substance used in the present invention is not particularly limited, but those which can be easily volatilized in view of the water resistance of the coating film are preferable, and examples thereof include
Examples thereof include ammonia or organic amines such as monoethanolamine, dimethylamine, diethylamine, triethylamine, triethanolamine, dimethylethanolamine, diethylethanolamine, and morpholine, but are not limited thereto.

The aqueous amino resin used in the present invention includes urea resin, melamine resin, benzoguanamine resin, melamine benzoguanamine co-condensation resin, diguanamine resin having two triazine rings bonded to a phenylene nucleus, glycollauryl resin and methylol thereof. , Methyl etherified and methyl / butyl mixed etherified modified resins. The content of the resin is preferably 20 to 60% by weight based on the total solid content of the resin. If the content is less than that, the scratch resistance is high, and if the content is high, the retort resistance and processability are not satisfied.

The polyester film-coated water-based paint composition for a squeezer can of the present invention may be mixed with a water-soluble resin or a water-dispersible resin, that is, a polyether polyol resin, a polyester polyol resin and an epoxy resin, if necessary. Is. Similarly, a leveling agent, a defoaming agent, and a lubricant can be added.

[0022]

EXAMPLES The present invention will be described in detail below with reference to examples, but these examples do not limit the present invention. In the following Production Examples, Examples and Comparative Examples, "parts" means "parts by weight" and "%" means "% by weight" unless otherwise specified, and amine block type acid catalysts are shown by the amount of active ingredient. [Preparation Example 1] Preparation of amine block type acid catalyst A having a dissociation temperature of 45 to 65 [deg.] C. Diethylamine was gradually added to P-toluenesulfonic acid, and the mixture was neutralized with PH = 7 as the end point to PH = 7 to neutralize the amine block. A type acid catalyst A was obtained. [Preparation Example 2] Preparation of amine block type acid catalyst B having a dissociation temperature of 100 to 120 ° C. N-methylmorpholine was gradually added to dodecylbenzenesulfonic acid, and the mixture was neutralized with PH = 7 at the end point of PH = 7. Amine block type acid catalyst B was obtained. [Adjustment Example 3] Adjustment of amine block type acid catalyst C having a dissociation temperature of 120 to 140 ° C. 2- (Dimethylamino) ethanol was gradually added to phosphoric acid methyl ester, and PH = 7 was mixed with PH = 7 as an end point. Neutralization gave an amine block type acid catalyst C. [Preparation Example 4] Preparation of amine block type acid catalyst D having a dissociation temperature of 150 to 170 ° C. Dibutylamine was gradually added to dinonylnaphthalenesulfonic acid, and PH was neutralized with PH test paper at pH = 7 as an end point. A block type acid catalyst D was obtained. Production Example 1 Production of Aqueous Acrylic Resin A Butyl cellosolve 100 was placed in a four-necked flask equipped with a thermometer, a stirrer, a reflux condenser, a dropping tank, and a nitrogen gas blowing tube.
While maintaining the temperature at 105 ° C. with stirring while introducing nitrogen gas, 20% styrene, 20% ethyl acrylate, 30% butyl acrylate, 10% hydroxyethyl acrylate, 10% acrylic acid were added from the dropping tank. A solution prepared by dissolving 5 parts of benzoyl peroxide in 100 parts of a mixture of 10% methyl methacrylate was added dropwise over 2 hours.
Then, after keeping the temperature at 105 ° C for 1 hour to react, butyl cellosolve was distilled off under reduced pressure until the nonvolatile content became 83%,
After cooling to 60 ° C. or lower, 14.6 parts of diethanolamine and water were added, and the non-volatile content was 50% and residual butyl cellosolve 1 was added.
A 0% transparent and viscous aqueous acrylic resin A was obtained.

Examples 1 to 7, Comparative Examples 1 to 7 Composition ratios of amine block type acid catalysts A to D, aqueous acrylic resin A and benzoguanamine resin (CYMEL 1123 manufactured by Mitsui Cyanamid Co., Ltd.) shown in Tables 1 and 2. And mix with water and butyl cellosolve to a non-volatile content of 4
A coating material was prepared by adjusting the solvent content to 0% and the solvent content to 15%.

[0024]

[Table 1]

[0025]

[Table 2]

The coating film physical properties of the coating materials prepared in Examples and Comparative Examples are shown in Table 3. Each test method in Table 3 is as follows. ○ Conditions for creating test coated plate Roll coating is applied to a polyester film-coated squeeze can so that the thickness of the coating film after drying is 4 to 5 μm, and the temperature is set to 1 at an ambient temperature of 220 ° C. in a gas oven.
Baked for minutes. Next, the paint can was opened and flattened to obtain a test painted plate. ○ Adhesion After performing a steam retort treatment at 130 ° C. for 30 minutes, cellophane tape was adhered to the place where the cross cut was made with a cutter knife, and the peeled state of the coating film after peeling it was evaluated. ○ Retort resistance The whitening state of the coating film after steam retort treatment at 130 ° C for 30 minutes was evaluated. ○ Scratch resistance After performing a steam retort treatment at 130 ° C for 30 minutes, a hard sphere subjected to a load of 1 kg was applied to the coating film, and a scratching state of the coating film was evaluated after performing an abrasion friction test. Workability The coated plate was punched out into a cap shape having a diameter of 3 cm and a height of 3 cm, and the state of cracks in the coating film after steam-type retort treatment at 130 ° C. for 30 minutes was evaluated. Gloss The gloss of the coating film after the steam retort treatment at 130 ° C. for 30 minutes was evaluated. The evaluation criteria in the above test methods are ◎ very excellent, ○ excellent, △ somewhat inferior, × inferior,
And

[0027]

[Table 3]

[0028]

The water-based coating composition of the present invention, that is, the water-based coating composition in which several kinds of block-type acid catalysts, which are stepwise adjusted to a predetermined dissociation temperature, are used in combination with the acrylic / amino resin is
When used as the outer top coat of polyester film-coated squeezer, it is possible to apply coating with excellent adhesion to polyester film, retort resistance, scratch resistance, processability and glossiness. It is very effective as a coating composition.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiharu Otsuka 2-3-13 Kyobashi, Chuo-ku, Tokyo Toyo Inki Manufacturing Co., Ltd.

Claims (1)

[Claims] 1. A solid component 1 of a resin composition comprising an aqueous acrylic resin as a main component and an aqueous amino resin as a curing agent therefor.
With respect to 00 parts, 0.05 to 2 parts of an amine block type acid catalyst adjusted to a dissociation temperature of 45 to 65 ° C. as an active ingredient,
0.05 to 2 parts of an amine block type acid catalyst adjusted to a dissociation temperature of 100 to 120 ° C. with an active ingredient and / or 0.05 to an amine block type acid catalyst adjusted to a dissociation temperature of 120 to 140 ° C. with an active ingredient. .About.2 parts and / or 0.05 to 2 parts of an amine block type acid catalyst adjusted to a dissociation temperature of 150 to 170.degree.