JPS60238370A - Coating compound composition - Google Patents

Abstract

PURPOSE:A coating compound composition useful for metallic cans, etc., providing a film having improved corrosion resistance in a short time, obtained by modifying bisphenol epoxy resin with a higher fatty acid to give an epoxy ester resin, curing and crosslinking the epoxy ester resin with a resol type phenolic resin and an amine. CONSTITUTION:(A) 100pts.wt. epoxy ester resin composition in which bisphenol epoxy resin is partially modified obtained by reacting (i) 100pts.wt. bisphenol epoxy resin with (ii) 5-100pts.wt. higher fatty acid, (B) 5-100pts.wt. resol type phenolic resin, and (C) 5-100pts.wt. amino resin are dissolved in an organic solvent, to give the desired composition. EFFECT:Providing a film having improved content property resistance and retort resistance, not causing sulfurization and blacking on cans.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coating composition, and more particularly to a coating composition useful for metal applications, particularly for metal can applications, which can form a coating film with excellent corrosion resistance by baking at high temperatures and short times. .

From the viewpoint of streamlining the coating process, it is desired that these coating compositions form an excellent coating film under high temperature and short baking conditions, and this requirement is particularly important when applied to pots and metal cans. strict.

To take one example of metal can applications, conventional metal cans are soldered iron cans, adhesive cans, and welded cans based on the method of joining one can body, but from the cost standpoint, the equipment space required for can manufacturing is small. Welded cans are becoming increasingly popular due to their advantages and the high mechanical strength of the can. However, in the case of welded cans, both cut ends of the can body material are welded overlapping (lap seam), so the cut ends are exposed to the inside of the can unpainted. The heat causes the tin to reflow, and in the case of tin-free steel, corrosion tends to occur from the metal surface, which is shaved to make it easier to weld. For this reason, in order to protect these welded parts, conventionally a method has been adopted in which a repair paint is applied to form a protective film, which is generally a thermoplastic resin paint such as a vinyl chloride copolymer, or an epoxy-amino paint.

Thermosetting resin coatings such as epoxy-phenolic and epoxy-acrylic are used.

However, although it is possible to form a film in a short time with thermoplastic resin paints, in the case of food and beverages, they are not sufficiently resistant to acids and can be subjected to high-temperature retort treatment for sterilization. It has drawbacks in terms of corrosion resistance and content resistance. In addition, the above-mentioned epoxy-based thermosetting resin paints form a coating film with excellent corrosion resistance if baked at 200°C for a long time of about 5 minutes, but if baked for less than 1 minute, especially less than 30 seconds, If baked for a short time, even at a high temperature of about 240-260°C, it will not harden sufficiently and a coating film with excellent corrosion resistance will not be obtained.

Furthermore, the above-mentioned paint has the disadvantage that it cannot prevent sulfide blackening that occurs when the material is electric tinplate.

In view of the above-mentioned current situation, the present invention provides a novel coating composition which has excellent content resistance and retort resistance and does not cause sulfide blackening, using baking conditions of high temperature and short time.
That is, the present invention provides bisphenol type epoxy resin 10
It is obtained by reacting 0 parts by weight with 5 to 100 parts by weight of a higher fatty acid. 100 parts by weight of an epoxy ester resin composition obtained by modifying at least a portion of the above bisphenol type epoxy resin, 5 parts by weight of a resol type phenol resin
100 parts by weight of an amino resin and 5 to 100 parts by weight of an amino resin are dissolved in an organic solvent.

The epoxy ester resin composition used in the present invention is
Bisphenol A type epoxy resin, hydrogenated bisphenol A type epoxy resin, and bisphenol are also modified by esterification of some resins. Examples of the higher fatty acids include linoleic acid, linuric acid, dehydrated castor oil fatty acid, soybean oil fatty acid, coconut oil fatty acid, m-oil fatty acid, sesame oil fatty acid, linseed oil fatty acid, Hygiene (trade name of Soken Chemical Co., Ltd.), etc. Unsaturated higher fatty acids are preferred.

In particular, when the iodine value is measured, the value is between 80 and 19.
0. More preferably, higher fatty acids in the range of 130 to 190 are used alone or in mixtures.

The amount of higher fatty acids used is 1 bisphenol type epoxy resin.
5 to 100 parts by weight of higher fatty acids per 00 parts by weight,
Preferably, the amount is 30 to 70 parts by weight; if the amount of higher fatty acid used is more than 100 parts by weight, the flavor suitability for the contents of the coating film will decrease, which is not preferable, whereas if it is less than 5 parts by weight, sulfur blackening will occur. Easy to occur. Modification of bisphenol type epoxy resin with higher fatty acids is preferably carried out in an organic solvent at a reaction temperature of 200 to 230°C.

The reaction time can be 1 to 3 hours.

The resol type phenolic resin in the present invention is obtained by reacting phenols with formalin in the presence of an alkali catalyst such as sodium hydroxide, magnesium hydroxide, lithium hydroxide, or ammonia. As the phenols, one or more of phenols such as carbolic acid, p-cresol, 0-cresol, m-cresol, bisphenol A, p-tertbutylphenol, p-phenylphenol, and xylenol can be used. Preferably, ammonia aresol using ammonia as a catalyst is used.

The amino resin may be one obtained by reacting urea, melamine, a triazine compound, or a mixture thereof with formaldehyde, and etherified with m alcohols having 1 to 4 carbon atoms.

The blending ratio of the epoxy ester resin composition and the resol type phenol resin is 5 parts by weight to 1 part by weight of the resol type phenol resin per 100 parts by weight of the epoxy ester resin composition.
00 parts by weight, preferably 5 to 50 parts by weight,
If the resol type phenolic resin is less than 5 parts by weight, corrosion resistance, content resistance, and sulfide blackening will be reduced, and if it is more than 100 parts by weight, processability will be reduced.

The mixing ratio of the epoxy ester resin composition and the amino resin is 5 parts by weight of the amine resin to 1 part to 100 parts by weight, preferably 5 to 50 parts by weight, and 5 parts by weight of the amino resin to 100 parts by weight of the epoxy ester resin composition. If the amount is less than 100 parts by weight, corrosion resistance and content resistance will decrease, while if it is more than 100 parts by weight, processability will decrease.

When the coating composition of the present invention is used particularly as a repair coating,
Polyolefin resins, modified polyolefin resins, and polyester resins are used to improve coverage of sharp parts such as welded steps and material cut edges, and to improve the processability of coating films.

Fine particles of thermoplastic resin such as polyamide resin, polyacetal resin, polycarbonate resin, acrylic resin, ABS resin, styrene-acrylonitrile copolymer, etc. shall be blended as a dispersion in an amount of 50 parts by weight or less per 100 parts by weight of the solid content of the paint. Can be done.

The most important feature of the present invention is that an epoxy ester resin obtained by modifying a bisphenol type epoxy resin with a higher fatty acid is cured and crosslinked with a resol type phenol resin and an amino resin. The reaction between epoxy ester resin and amino resin is faster than the self-condensation of epoxy ester resin and the reaction between epoxy ester resin and phenol resin, and the self-condensation of phenol resin itself is faster than the reaction with epoxy ester resin and amino resin. As a result, it is presumed that the phenol resin floats in the form of islands in the epoxy ester resin-amino resin crosslinked network structure, and that this has a structure crosslinked with the epoxy ester resin or amino resin.

The above reaction is extremely fast, especially for epoxy ester resins and amino resins, so baking can be carried out in a short period of time. Furthermore, the phenol resin floats in the form of islands and has a high crosslinking density, so it has excellent corrosion resistance, and the double bonds (derived from unsaturated fatty acids) in the phenol resin and epoxy ester resin mainly absorb hydrogen sulfide generated from the contents. It reacts with sulfur compounds, and in combination with the shielding effect due to its high crosslinking density, it prevents the occurrence of sulfide blackening on the base and has excellent content resistance.

The coating composition of the present invention is heated at 240°C or higher for 60 seconds.

It is possible to dry and bake in a short time at a high temperature of 25 seconds in some cases, and the resulting coating film has excellent corrosion resistance and prevents the occurrence of blackening due to sulfide, making it suitable for food cans, especially for fish and shellfish. It is useful as a repair paint for welded cans, and expands the range of uses for welded cans, including food cans, which were not previously available.

The coating composition of the present invention contains phosphoric acid to accelerate curing.

Acidic substances such as phosphoric acid esters, p-)luenesulfonic acid and trimellitic acid, salts such as zinc octylate and zinc naphthenate, and organic metal compounds such as aluminum alcoholade and alkyl titanate can be blended.

Other conventional additives such as coloring dyes and pigments, rust-preventing pigments, fillers, surfactants, detergents, etc. can be used in the coating composition according to the invention.

A method for applying the coating composition of the present invention is as follows.

Known means such as spraying, roll coating, brush coating, flow coating, etc. can be used.

The coating composition of the present invention is useful not only as a repair coating for welded cans, for repairing the inner and outer surfaces of side seams, but also for other products that require short baking times, such as coil coating coatings for beverage can lids, and architectural coatings. It is also useful as a paint for coating wood panels. Of course, 170℃~220℃ for 10 minutes~
It can also be used as a 20-minute baking paint for food cans and beverage cans. The present invention will be specifically explained below with reference to Examples. In the examples, "parts" and "%" are "parts by weight."

Indicates "% by weight".

Bisphenol A type epoxy resin AER66 in the epoxy ester resin manufacturing flask
7 (manufactured by Asahi Kasei Industries, Ltd.) 100 copies.

40 parts of soybean oil fatty acid and 10 parts of xylene were charged and kept at 220°C for 3 hours with stirring. The reaction was terminated when the acid value became 10 or less, and 100 parts of Tsurupetz 100 and 100 parts of Tsurupetz 150 were added and cooled to obtain an epoxy ester resin (a) solution.

Thereafter, solutions of epoxy ester resins (b), (C) and (d) were obtained using the raw materials and blending amounts shown in Table 1 by the same operations as above.

``Phenol resin manufacturing flask contains 100 parts of p-cresol and 30 parts of formalin.
% aqueous solution) 70 parts, 20% aqueous solution of sodium hydroxide 2
1 part was charged and kept at 100°C for 2 hours while stirring. Next, 1,770 parts of xylene, 70 parts of n-butanol, and 70 parts of cyclohexanone were added, cooled, and neutralized with 9-hydrochloric acid. The aqueous layer was removed with decanethiolone, and the solvent layer was washed twice with the same amount of water. 9 The mixture was then dehydrated by reflux to obtain a solution of the phenol resin (e).

Solutions of phenolic resins (f), (g), (h) and (i) were obtained using the raw materials and blending amounts shown in Table 2 by the same operation as above.

Table 2 Example epoxy ester resin, after resol type phenol, organic solvent (butyl cellosolve acetate/ethyl cellosolve acetate/Tsurpetz 100/xylene/isopropyl alcohol-20 /20/20/20/20
) and used as a welding can repair paint.

Example Work to Example 4 and Comparative Example 1 to Comparative Example 8
After storing the resulting paint at room temperature for one month, we conducted a paint stability test to observe the state of gelation and separation of the resin.

Next, cut out a section of the side seam of a tin IKg round can welded using a can making machine (manufactured by Sudronics), and apply these paints on the inner surface with a brush to obtain a coating thickness of 15μ on the flat plate part. Paint it like this.

Then, it was baked for 20 seconds using a gas burner. Baking was set so that the plate temperature reached 255°C after 20 seconds. The coated welded part was cut into 3 cm x 7 marks to make a test piece, immersed in the contents of a well-ground salmon boiled can, and re-made at 117°C.
After being retorted for 90 minutes at 50° C. and stored at 50° C. for 20 days, the corrosion state and sulfide blackening state were evaluated (-Ill-Kekansu Pasoku test).

Similarly, a test piece was immersed in 1% saline, retorted at 117°C for 90 minutes, and stored at 50°C for 20 days to evaluate the corrosion state (accompanied saline water test).

Next, the applied welded part was bent and the occurrence of cracks was observed (workability test).

Table 4 shows the storage stability and coating film test results of the paints obtained in Examples and Comparative Examples. The paints obtained in Examples 1 to 4 have no sulfide blackening and have excellent corrosion resistance and processability, whereas the paints obtained in Comparative Examples have particularly It is not practical as a welding can repair paint because of the poor balance between sulfide blackening, corrosion resistance, and workability.

Example 5 20 parts of fine powder of nylon 11 having an average particle size of 10 μm was added to 100 parts of the solid content of the paint obtained in Example 1 while stirring at high speed to obtain a welding can repair paint.

Example 6 40 parts of fine powder of nylon 11 having an average particle size of 10 μm was added to 100 parts of the solid content of the paint obtained in Example 1 while stirring at high speed to obtain a welding can repair paint.

Example 7 20 parts of fine powder of nylon 12 having an average particle size of 10 μm was added to 100 parts of the solid content of the paint obtained in Example 2 while stirring at high speed to obtain a welding can repair paint.

Example 8 40 parts of fine powder of nylon 12 having an average particle size of 10 μm was added to 100 parts of the solid content of the paint obtained in Example 2 while stirring at high speed to obtain a welded can repair paint.

Example 9 Fine powder of carboxyl group-modified polypropylene with an average particle size of 5 μm was added to 100 parts of the solid content of the paint obtained in Example 2.
Add 5 parts with high speed stirring.

Obtained welding can repair paint.

The welded can repair paints obtained in Examples 5 to 9 were painted and baked in the same manner as in Example 1 to improve coating film performance. The results are shown in Table 5.

Continuation of page 1

Claims (1)

[Claims] 1. Obtained by reacting 100 parts by weight of a bisphenol type epoxy resin with 5 to 100 parts by weight of a higher fatty acid. Epoxy ester resin composition 10 obtained by modifying at least a part of the above bisphenol type epoxy resin
1. A coating composition comprising: 0 parts by weight, 5 to 100 parts by weight of a resol type phenolic resin, and 5 to 100 parts by weight of an amino resin, dissolved in an organic solvent.