JPS6197372A - Inner surface coating for alcoholic drink can and can body coated with same - Google Patents

Abstract

PURPOSE:To provide the title coating consisting of vinyl chloride resin, vinyl chloride copolymer resin, epoxy resin, oil soluble phenolic resin and solvent and forming a coating film excellent in workability, resistance to corrosion and alcohol and retention of appearance. CONSTITUTION:The coating compsn. consisting of a PVC organosol is prepd. by mixing (A) 30-60pts.wt. vinyl chloride resin which is a vinyl chloride paste resin having an average degree of polymerization 1,000-1,800, (B) 30-60pts.wt. vinyl chloride copolymer resin which contains 50wt% or higher carboxyl group- contg. vinyl chloride/vinyl acetate copolymer, (C) 1-6pts.wt. epoxy resin obtained by condensation of bisphenol A with epichlorohydrin and having a number-average M.W. of 300-1,000 and an epoxy equivalent of 180-500, (D) 3-10pts.wt. oil-soluble resol type phenolic resin obtained by condensation of p-cresol and/or bisphenol A with HCHO in the presence of an alkaline catalyst and (E) organic solvent in such blend ratios that C+D/A+B+C+D may be 0.04-0.16 and C/D may be 2:1-1:3 by weight.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention relates to a vinyl chloride resin organosol coating suitable as an inner surface coating for alcoholic beverage cans, and a can using the same.

(Prior Art) Conventionally, alcoholic beverages such as wine, sake, shochu, anti-high drinks, and beer have been used in containers such as glass containers and metal cans, but alcoholic beverages are generally used in containers such as other soft drinks. Their flavor is subtle compared to water, etc., and the containers used to fill these contents must have a high degree of flavor retention so that the flavor of the contents does not deteriorate even after long-term storage. be. Metal cans generally have many advantages such as good protection of contents, light weight, and easy storage and transportation, and there is a high demand for their use as containers for alcoholic beverages, but compared to glass containers, they do not retain flavor well. Metal cans are rarely used, except for beverages (beer and some alcoholic beverages).

Therefore, there has been a strong desire to develop metal cans with excellent flavor retention.

(Problem to be solved by the invention) There are various reasons why the flavor changes when alcoholic beverages are packed in metal cans. The interaction between the contents and the coating, such as the adsorption of small amounts of components extracted from the protective coating on the inner surface of the can, the adsorption of flavor components in the contents to the coating, or the small amount of components extracted from the defective parts of the coating on the inner surface of metal cans. It is assumed that this is due to eluted metals, etc., and in order to obtain a metal can with excellent flavor retention, it is necessary to have good workability and corrosion resistance to prevent metal leaching, and to have no coating defects such as pinholes. Excellent alcohol resistance,
It is necessary to use a paint that forms a coating on the inside of the can that does not interact with the contents. Epoxy phenol resin paints and epoxy urea resin paints, which have traditionally been used as interior paints for beverage cans, food cans, etc., tend to change flavor when used as interior paints for alcoholic beverage cans, resulting in better can interior surfaces. Paints and can bodies using the paints are desired.

(Means for Solving the Problem) The inventors of the present invention obtained a metal tagawa inner surface paint suitable for alcoholic beverages (as a result of studies, the inventors developed a coating film with a specific vinyl chloride resin organosol paint composition on the inner surface of the can). The metal cans are filled with ordinary alcoholic beverages with an alcohol concentration of 2% or more, and the flavor does not change even if stored for a long time (the can body also has no defects such as corrosion (the summer cans are of high quality). They discovered this and completed the present invention.

The gist of the present invention is that the nonvolatile composition of the vinyl chloride resin-based Orcasol paint is vinyl chloride resin 30-60 parts by weight Vinyl chloride copolymer resin 30-60 parts by weight Epoxy resin 1-6 parts by weight Phenol resin 3
-10 parts by weight of alcohol, wherein the total amount of the epoxy resin and phenolic resin is 4-16% by weight of the total non-volatile content, and the weight ratio of the epoxy resin to the phenolic resin is in the range of 2:i- to 3: The present invention relates to an inner surface paint for beverage cans and a can body using the same on the inner surface of a metal can.

As the vinyl chloride resin used in the present invention, a so-called vinyl chloride paste resin, which is a homopolymer of vinyl chloride and has an average degree of polymerization of 1000 to 1800, can be used. For example, Zeon 121, Zeon 103BPF (manufactured by Nippon Zeon Co., Ltd.), etc. can be used. In addition, as the vinyl chloride copolymer resin, vinyl chloride-vinyl acetate copolymer containing a carboxyl group, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate copolymer containing a hydroxyl group, etc. were used alone or in combination. Resin can be used. Examples of vinyl chloride-vinyl acetate copolymers containing carboxyl groups include Vinylite MCH and VMCC (Union Carbide); examples of vinyl chloride-vinyl acetate copolymers include Vinylite YHH, VYHD and VYNS-. 3
(Company), VAG H, VAGD (Company) as vinyl chloride-vinyl acetate copolymers containing hydroxyl groups.
Company) etc. can be used. The vinyl chloride resin used in the present invention has good alcohol resistance, no paint film extraction components, and does not adsorb flavor components of the contents, so it has excellent flavor retention, but it has poor adhesion to the metal surface of the can body. was insufficient, so a chloride-vinyl copolymer resin with good adhesion was used.
It is necessary to use it in the range of 0-60 parts by weight. As such a vinyl chloride copolymer resin, a resin containing 50% by weight or more of a carboxyl group-containing vinyl chloride-vinyl acetate copolymer is particularly preferred since it has good adhesive properties. Moreover, the above-mentioned copolymer having such a reactive group is an epoxy resin.

It also has the effect of performing a crosslinking reaction with phenolic resins, etc., and improving the heat resistance, flavor retention, etc. of the coating film. In addition, as an epoxy resin, the number average molecule z3oo-1o obtained by condensation of bisphenol A and epichlorohydrin is used.
oo having an epoxy equivalent of 180-500 is suitable, such as Epicor-1-828, Epicor-832. 834. 836. 871, 1001 (manufactured by Shell Chemical), etc. can be used. In addition, as the phenolic resin, P-cresol, 0-cresol, M-cresol, P-t-butylphenol, P-amylphenol,
Suitable are those containing a resol type phenolic resin obtained by reacting at least -m such as bisphenol A with formaldehyde using an alkali metal, alkaline earth metal hydroxide, or ammonia as a catalyst, Particularly preferred are P-cresol or a phenol resin obtained by reacting bisphenol A and formaldehyde using the above-mentioned alkali catalyst, either alone or in combination. When producing the above phenolic resin, the ratio of phenols and formaldehyde is 1 mole of phenols to 0 formaldehyde.
．． A range of from 8 to 3 moles is suitable, and from 0.01 to 0.0 moles of the alkali catalyst as described above is suitable. Used in a small amount of Tachibana mole, 9
It is obtained by reacting at a temperature of about 0 degrees Celsius for 1 to 3 hours, and particularly has a number average molecular weight of 300 to 1000 and a ratio of 3 weight average molecular weight/number average molecular weight of 4.0 or less, preferably 2.
A range of 5 or less is suitable. In these phenol resins, the methylol group may be alkyl etherified.

Phenol resins are generally made by reacting phenols with formaldehyde using an ammonia catalyst, but when an ammonia catalyst is used, flavor retention becomes unstable depending on the type of alcoholic beverage. On the other hand, when an alkaline earth metal or alkali metal hydroxide 1, such as magnesilla hydroxide, sodium hydroxide, potassium hydroxide, etc., is used as a catalyst, the obtained phenolic resin has flavor stability. In the present invention, the epoxy resin and the phenol resin are used as paints containing vinyl chloride resin.
It acts as a heat stabilizer to prevent the thermal decomposition of vinyl chloride resin when baking to form a coating film at a temperature of 200 degrees C or above, and also increases the hardenability of the coating film, improving adhesion and corrosion resistance.

It also has the effect of improving alcohol resistance, etc.2 In the nonvolatile composition of the present invention, the epoxy resin is
If the amount of phenolic resin is less than 3 parts by weight, or if the total amount of both resins is less than 4% by weight of the total non-volatile components, the thermal stability of the coating film during baking will be poor.
Corrosion resistance is also poor, and the effect of improving adhesion to the base metal cannot be expected. Also, if the amount of epoxy resin is more than 10 parts by weight, if the amount of phenolic resin is more than 10 parts by weight, or if the total amount is more than 15% by weight based on the total non-volatile components, the amount of components extracted from the paint film will increase and the alcoholic beverage content will increase. This is undesirable as it changes the flavor of the food.

In the coating composition of the present invention, an organic solvent is used in addition to the above-mentioned nonvolatile components. Any organic solvent that does not dissolve the vinyl chloride resin but dissolves other components can be used. As such a solvent, known alcohol-based solvents, ketone-based solvents, ester-based solvents, ether-based solvents such as cellosolves, aromatic solvents, and other solvents can be appropriately used alone or in combination.

The coating composition of the present invention is not particularly limited in its baking method, and can be applied by roll coating on aluminum plates, tin-plated steel plates, tin-free steel plates, etc., or by drawing and ironing on aluminum plates and tin-plated steel plates. A coating film can be formed on the inner surface of (DI cans) and impact cans by spray painting and baking in an oven.

Two-piece cans or three-piece cans with a coating film made of the coating composition of the present invention provided on the inner surface of the can are used as can bodies for alcoholic beverages, but two-piece cans made of aluminum or tin-plated steel sheets are also used. After applying chemical conversion treatment to the inner surface of the can, a coating film of 2 to 10 microns is formed on the can body.Even if the can is filled with alcoholic beverages and stored for a long period of time, there will be no abnormality in the can, and the flavor of the contents will not change. I love this.

Next, a detailed description will be given with reference to Examples, where parts are by weight.

(Example) Synthesis Example I 1 mol of P-cresol, 1 mol of formaldehyde (37
% aqueous solution) and 0.02 mol of magnesium hydroxide were reacted at 95 degrees C for 3 hours. after that
The alkaline catalyst was neutralized using phosphoric acid, and after washing with water, the side fat layer was mixed with 30 parts of methyl isobutyl ketone and 30 parts of cyclohexanone.
After extraction with a mixed solvent consisting of 40 parts of phenol resin (A), the mixture was washed with water, the aqueous layer was removed, and the water was removed by azeotroping to obtain a solution of phenol resin (A) with a concentration of 30 parts.

Synthesis Example 2 A mixture consisting of 0.6 mol of bisphenol A, 0.4 mol of P-cresol, 2 mol of formaldehyde (37% aqueous solution), and 0.02 mol of magnesium hydroxide was reacted at 95 degrees C for 3 hours. Thereafter, in the same manner as in Synthesis Example 1, a solution of phenol resin (B) with a concentration of 30 parts was obtained.

Synthesis Example 3 Bisphenol Δ1 mol, formaldehyde 2 mol (3
7% aqueous solution), ammonium hydroxide 0.12 mol (
(25% aqueous solution) was reacted at 90 degrees C for 3 hours. After that, 30% of phenol resin (C) was added in the same manner as in Synthesis Example 1.
I got a solution.

Synthesis Example 4 A mixture consisting of 1 mol of coal, 1.5 mol of formaldehyde (37% aqueous solution), and 0.12 mol of ammonium hydroxide (25% aqueous solution) was reacted at 85 degrees C for 1.5 hours. Thereafter, in the same manner as in Synthesis Example 1, a 30 parts solution of phenol resin (D) was obtained.

Example 1 Vinyl chloride copolymer resin Vinyrite VMCH (manufactured by Union Carbide) 44 was added to 200 parts of a solvent consisting of methyl ethyl ketone, toluene, xylene, and diisobutyl ketone.
Part, epoxy resin Epicoat 834 (Shell Chemical) 4
of the phenolic resin (A) obtained in Synthesis Example 1.
26.7 parts of a 30% solution of ) was added. Next, add 44 parts of vinyl chloride resin Zeon 121 (Nippon Zeon) and stir 1.
A vinyl chloride resin-based organosol paint (1) having a viscosity of 20 seconds (Ford cup characteristic: 4.25 degrees Celsius) was obtained by dispersing the polyvinyl chloride resin in a solvent similar to the above-mentioned solvent.

Next, after carrying out a chemical conversion treatment on the inner surface of a drawn and ironed air aluminum can with a content capacity of 350 ml, the paint (1) was applied by airless spray painting and baked at 200 degrees Celsius for 3 minutes to obtain a film thickness of approx. A can (1) with an inner surface coated with a coating film of 6 microns was obtained.

Example 2 46 parts of Vinyrite VMCH, 3 parts of Epicote 834,
A vinyl chloride resin organosol paint with a viscosity of 20 seconds (2
) was prepared, painted and baked on the same aluminum can as in Example 1,
Cans coated on the inside with a coating film of approximately 6 microns thick (2
) was obtained.

Example 3 Phenol resin (B) instead of phenol resin (A)
An organosol paint (3) was prepared in the same manner as in Example 1 except that the same amount of the same amount was used, and the organosol paint (3) was baked on an aluminum can to obtain an inner-coated can (3).

Example 4 Phenol resin (B) instead of phenol resin (A)
An organosol paint (4) was prepared in the same manner as in Example 2 except that the same amount of the above was used, and an internally coated can (4) having a film thickness of about 6 microns was obtained using this.

Example 5 Phenol resin (C) instead of phenol resin (A)
An organosol paint (5) was prepared in the same manner as in Example 1 except that the same amount of the above was used, and an internally coated can (5) was obtained using this.

Example 6 Phenol resin (C) instead of phenol resin (A)
Using the same amount of paint (
6) was prepared, and an inner surface coated can (6) using this was obtained.

Comparative Example 1 Vinylite VMCH 30 parts, Vinylite VAGI (10 parts
A paint (7) was prepared in the same manner as in Example 1, except that 4 parts of Epicoat 834, 23.3 parts of a 30% solution of phenolic resin (D), and 50 parts of Zeon 121 were used.
Using this, an inner-coated can (7) was obtained.

Comparative Example 2 Non-volatile component is Epicoat 1007 (Shell Chemical) 4
8 copies, Epicor) 1009 (Company) 47 copies.

An epoxy phenol resin paint (8 parts) consisting of 5 parts of a resol type phenol resin obtained by reacting bisphenol A and formaldehyde with magnesium hydroxide as a catalyst.
) (This paint is a typical epoxy phenol resin paint that has traditionally been used as the inner surface paint for single-serve beverage cans.) It was applied in the same manner as in Example 1 and heated at 210 degrees C for 3 minutes. The inside of the can is baked to a film thickness of approximately 6 microns (
8) was obtained.

Next, the above-mentioned inner-coated cans were used to evaluate the following items. The results are shown in the table.

(B) Flavor retention Commercially bottled sake, wine, high-quality sake, and beer are sealed in cans with a coated interior and stored at 37 degrees Celsius for three months. -20 people evaluated on a 4-level scale.

◎ (no difference from the bottle), ○ (very slight difference), △ (slight difference), × (considerable difference) (b) Corrosion resistance When the can filled with the above contents is opened. The state of corrosion on the inner surface of one can was observed and evaluated.

○ (no corrosion), △ (slight corrosion).

× (High corrosion) (c) Ethanol extraction rate A test piece was taken from the body of the inner-coated can and placed in ethanol, heated to boiling, and extracted. The amount extracted in ethanol (a) and the test after extraction. The extraction residue b) after aluminum was removed from the piece (dissolved with acid) was weighed, and the ethanol extraction rate (100·a/a + b) was calculated.

As is clear from the results shown in Table 11 and Table 2, cans using the vinyl chloride resin organosol paint of the present invention have excellent quality as cans for alcoholic beverages.

(Effects of the Invention) As described above, according to the present invention, 2. The non-volatile composition of the vinyl chloride resin organosol paint consists of 30-60 parts by weight of vinyl chloride resin, 30-60 parts by weight of vinyl chloride copolymer resin, 1-6 parts by weight of epoxy resin, 3-10 parts by weight of phenol resin, and the epoxy resin and phenol. The total amount of resin is 4-16% by weight of the total non-volatile content, and the weight ratio of epoxy resin and phenolic resin is in the range of 2:1-1:3, so it has good processability and corrosion resistance. No coating defects such as pinholes and excellent alcohol resistance.
It is possible to obtain a coating that forms a coating film on the inside of a can that does not interact with the contents (and does not affect the flavor of alcoholic beverages).By providing the coating on the inside of a can, when filled with alcoholic beverages This has the effect of making it possible to obtain a can body with excellent flavor retention.

Table-1 Table-2 Procedural Amendment Form) % Formula % 2. Name of Invention: Can Inner Paint for Alcohol Beverage Cans and Can Body Using (3), Relationship with the Person Who Made the Amendment Patent Applicant Kita # Seikan Co., Ltd. 4, Agent 5, Voluntary action on the date of the amendment order) 6. As per the content of the amendment (no change in content) Description Name of the invention Can inner surface paint for alcoholic beverage cans and the same The claimed scope of the can body patent is that the non-volatile composition of the vinyl chloride resin organosol paint is vinyl chloride resin 3G-60 parts by weight (6) parts vinyl chloride copolymer resin 30-60 parts by weight epoxy resin 1-6 parts by weight oil-soluble phenolic resin
3-10 parts by weight, the total amount of the epoxy resin and the phenol resin is 4-16% by weight of the total non-volatile content, and the weight ratio of the epoxy resin and the phenol resin is 2:1-1:3. An inner surface paint for alcoholic beverage cans, characterized in that the paint is within the range of:

2. The can inner surface coating according to item 1, wherein the oil-soluble phenolic resin is a resol type 71-nol resin obtained by condensing at least one pole of P-cresol and bisphenol A, either alone or in combination.

3. The number average molecular weight of the epoxy resin obtained by combining bisphenol A and epichlorohydrin is 300-10.
00 and an epoxy resin having an epoxy resistance of 180-500.

4. The interior paint for cans according to item 1 above, wherein the vinyl chloride copolymer resin is a vinyl chloride copolymer resin containing 50% by weight or more of a vinyl chloride-vinyl acetate copolymer having a carboxyl group.

5. The non-volatile component composition is vinyl chloride resin 3G-60 hanging part vinyl chloride copolymer resin 30-130 parts by weight epoxy resin 1-8 parts by weight oil-soluble phenol resin 3-10 parts by weight, the epoxy resin and the phenol The total amount of resin is 4- in the total non-volatile matter.
An alcoholic beverage characterized in that the inner surface of the can is coated with a vinyl chloride resin organosol paint having a concentration of 16% by weight and a ff1tJt ratio of epoxy resin and phenolic resin in the range of 2:1 to 1:3. Can body for cans.

3. Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a vinyl chloride resin light organosol coating suitable as an inner surface coating for alcoholic beverage cans, and to cans using the same.

(Prior Art) Conventionally, alcoholic beverages such as wine, sake, shochu, anti-high drinks, and beer have been used in containers such as glass containers and metal cans, but alcoholic beverages are generally used in containers such as other soft drinks. Compared to water, etc., the flavor is subtle, and the containers used to fill these contents must have a high degree of flavor retention so that the flavor of the contents does not deteriorate even when stored in a long-term storage machine. be. Metal cans generally have many advantages such as good protection of contents, light weight, and easy storage and transportation, and there is a high demand for their use as containers for alcoholic beverages, but compared to glass containers, they do not retain flavor well. However, with the exception of beer and some alcoholic beverages, metal cans are rarely used, so there has been a strong desire to develop metal cans with excellent flavor retention.

(Problems to be Solved by the Invention) There are various possible reasons for the change in flavor that occurs when alcoholic beverages are packed in metal cans, but since the flavor changes greatly depending on the characteristics and corrosion resistance of the paint on the inside of the can, these The cause of this is the interaction between the contents and the coating, such as a small amount of components extracted from the inner protective coating of the metal can, the adsorption of flavor components in the contents to the coating, or defects in the inner coating of the metal can. minute m from
In order to obtain a metal can body with excellent flavor retention, it is necessary to have good processability and corrosion resistance, and to be free of coating film defects such as pinholes in order to prevent metal elution. It is necessary to use a paint that has excellent alcohol resistance and forms a coating on the inside of the can that does not interact with the contents.

Epoxyphenol resin paints and epoxyurea bA fat-based paints, which have traditionally been used as interior paints for beverage cans and food cans, tend to change flavor when used as interior paints for alcoholic beverages, making them even more superior. There is a need for a can inner surface paint and a can body using the same.

(Means for Solving the Problems) As a result of conducting studies to obtain an inner surface paint for metal cans suitable for alcoholic beverages, the inventor of the present invention applied a coating film of a specific vinyl chloride resin organosol paint composition to the inner surface of the can. It was discovered that the prepared metal can, filled with a general alcoholic beverage with an alcohol concentration of 2% or more, did not change in flavor even after long-term storage, and the can body had excellent color quality without defects such as corrosion. The invention has been completed.

The gist of the present invention is that the non-volatile composition of the vinyl chloride resin-based organosol paint is vinyl chloride resin, 3G-60 parts by weight, vinyl chloride copolymer resin, 30-60 m, and N part epoxy resin.
1-6 parts by weight oil-soluble phenolic resin
3-10 parts by weight, and the total amount of the epoxy resin and phenol resin is 4-16% by weight of the total non-volatile content.
and a can body using the same on the inner surface of a metal can.

As the vinyl chloride resin used in the present invention, a so-called vinyl chloride base resin, which is a homopolymer of vinyl chloride and has an average polymerization weight of 1000 to 1800, can be used. For example, Zeon 121, Zeon 103BPF (hereinafter manufactured by Nippon Zeon ■), etc. can be used.

Vinyl chloride copolymer resins include vinyl chloride-vinyl acetate copolymers containing carboxyl groups, vinyl chloride-vinyl acetate copolymers containing hydroxyl groups, and vinyl chloride-vinyl acetate copolymers containing no carboxyl or hydroxyl groups. Resins can be used alone or in combination with coalescence, etc. As a vinyl chloride-vinyl acetate copolymer containing a carboxyl group, for example, Vinylite VHCH1 VHCC (Union Carbide Co.) is used, and as a vinyl chloride-vinyl acetate copolymer, VYHH1 V'/110° VVNS-
3 (Company), and as the vinyl chloride-vinyl acetate copolymer containing a hydroxyl group, VAGH1, VAGD (Company), etc. can be used. The vinyl chloride resin used in the present invention has good alcohol resistance, has no paint film extracting components,
It has excellent flavor retention because it does not adsorb the flavor components of the contents, but its adhesion to the metal surface of the can is insufficient, so 30-6 vinyl chloride copolymer resin with good adhesion is used.
It is necessary to use it within the range of 0 parts by weight. As such a vinyl chloride copolymer resin, a resin containing 50% by weight or more of a vinyl chloride-vinyl acetate copolymer containing a carboxyl group in the copolymer resin has particularly good adhesive properties and is preferred. Further, the copolymer having such a reactive group performs a crosslinking reaction with an epoxy resin, a phenol resin, etc., and has the effect of improving the heat resistance, flavor retention, etc. of the coating film.

In addition, as an epoxy resin, number average molecule 113 obtained by condensation of hisphenol A and epichlorohydrin is used.
00-1000 and epoxy 1180-500 are suitable, such as Epicoat 828, 832, 8
34, 836, 871, 1001 (hereinafter manufactured by Shell Chemical), etc. can be used.

In addition, conventional phenolic resins include oil-soluble phenolic resins obtained from P-cresol, bisphenol A, O-cresol, P-t-butylphenol, P-amylphenol, etc., and oil-insoluble phenolic resins obtained from m-cresol, carbolic acid, etc. Phenol resins and the like are known, but P-cresol, 0-cresol, pt-butylphenol,
Oil-soluble resol type phenol resin obtained by reacting at least one type of P-amylphenol, bisphenol A, etc. with formaldehyde using an alkali metal or alkaline earth metal hydroxide, or ammonia as a catalyst, retains flavor. P-cresol, or oil-soluble resol type phenol resin obtained by reacting bisphenol A and formaldehyde using the above-mentioned alkali catalyst. The resin is delicious. When producing the above-mentioned phenolic resin, the ratio of phenols and formaldehyde is suitably in the range of 0.8 to 3 moles of formaldehyde per 1 mole of phenol, and the above-mentioned alkali catalyst is added in a range of 0.01 to 0.20. It is obtained by using a small amount of about mol and reacting at a temperature of about 90 degrees C for 1 to 3 hours, and especially has a number average molecular weight of 300 to 1000.
Those having a weight average molecular weight/number average molecular weight of 4.0 or less, preferably 2.5 or less are suitable in terms of flavor retention and coating film properties. These oil-soluble phenolic resins are
The methylol group may be converted into an alkyl ether.

Phenol resins are generally those obtained by reacting phenols and formaldehyde using an ammonia catalyst, but if an ammonia catalyst is used, wind line retention becomes unstable depending on the type of alcoholic beverage. In contrast, alkaline earth metals or alkali metal hydroxides,
For example, when magnesium hydroxide, sodium hydroxide, potassium hydroxide, etc. are used as a catalyst, the resulting phenolic resin has flavor stability.

In the present invention, the epoxy resin and the oil-soluble phenol resin are used when baking the vinyl chloride resin-containing paint at a temperature of 200 degrees C or less to form a coating film.
In addition to acting as a heat stabilizer to prevent thermal decomposition of , when the epoxy resin is 1 part by weight or less, when the oil-soluble phenol resin is 3 parts by weight or less,
Alternatively, if the total of both resins is less than 4% by weight of the total non-volatile components, the thermal stability of the coating film during baking will be poor, the corrosion resistance will also be poor, and the effect of improving adhesion to the underlying metal is expected. become unable. In addition, if the epoxy resin is more than 6 parts by weight, if the oil-soluble phenol resin is more than 10 ffl parts, or if the total amount is 1 part by weight based on the total non-volatile components,
If it exceeds 6% by weight, the amount of components extracted from the coating film will increase, which will change the flavor of the alcoholic beverage content, which is undesirable.

In addition, epoxy resins and phenol resins are components that perform crosslinking reactions with each other and also react with vinyl copolymers having carboxyl groups and hydroxyl groups in the resin composition,
From the viewpoint of coating film curability, weldability, flavor retention, etc., the ratio of epoxy resin to oil-soluble phenol resin is preferably 2/1 to 1/3, and the ratio of both resins is greater than 2/1. 1/
If it is less than 3, either the epoxy resin or the oil-soluble phenol resin tends to remain, and especially under short baking conditions, the low molecular weight components of the epoxy resin or the oil-soluble phenol resin may remain in the coating after baking. flavor retention becomes unstable.

In the coating composition of the present invention, an organic solvent is used in addition to the above-mentioned nonvolatile components. Any organic solvent that does not dissolve the vinyl chloride resin but dissolves other components can be used. Such solvents include known alcohol solvents,
Ketone solvents, ester solvents, ether solvents such as cellosolves, aromatic solvents, and other solvents can be appropriately used alone or in combination.

The coating composition of the present invention is not particularly limited in its baking method, and can be applied with a zero-coat coating to aluminum plates, soot-plated steel plates, ding-free steel plates, etc., and by drawing and ironing to aluminum plates and tin-plated steel plates. A coating film can be formed on the inner surface of cans (Of cans) and impact products by spray painting and baking in an oven.

Two-piece cans or three-piece cans with a coating film made of the coating composition of the present invention provided on the inner surface of the can are used as can bodies for alcoholic beverages, but two-piece cans made of aluminum or tin-plated steel sheets are also used. After applying chemical conversion treatment to the inner surface of the can, a coating film of 2 to 10 microns is formed on the can body.Even if the can is filled with alcoholic beverages and stored for a long period of time, there will be no abnormality in the can, and the flavor of the contents will not change. I love this.

(Example) Next, an example will be specifically explained, and parts are by weight.

Synthesis examples of phenolic resins used in the following Examples and Comparative Examples are as follows.

Synthesis Example 1 1 mol of P-cresol, 1 mol of formaldehyde (37
% aqueous solution) and 0.02 mol of magnesium hydroxide were reacted at 95 degrees C for 3 hours. Thereafter, the alkali catalyst was neutralized using phosphoric acid, and after washing with water, the shelf fat layer was extracted with a mixed solvent consisting of 30 parts of methyl isobutyl ketone, 30 parts of cyclohexanone, and 40 parts of xylene, and after washing with water, the aqueous layer was removed. Then, water was removed by azeotroping to obtain a 30% solution of oil-soluble phenol resin (color).

Synthesis Example 2 A mixture consisting of 16 moles of bisphenol A, 0.4 moles of P-cresol, 2 moles of formaldehyde (37% aqueous solution), and 0.02 El of magnesium hydroxide was heated at 95 degrees C.
The mixture was allowed to react for 3 hours. Thereafter, in the same manner as in Synthesis Example 1, a solution having a concentration of 30 parts of oil-soluble phenol resin (B) was obtained.

Synthesis Example 3 1 mole of bisphenol A, 2 moles of formaldehyde (3
7% aqueous solution), ammonium hydroxide 0.12 mol (
(25% aqueous solution) was reacted at 90 degrees C for 3 hours. Thereafter, in the same manner as in Synthesis Example 1, a 30% solution of oil-soluble phenol resin (C) was obtained.

Synthesis Example 4 A mixture consisting of 1 mol of carbolic acid, 1.5 mol of formaldehyde (37% aqueous solution), and 0.12 mol of ammonium hydroxide (25% aqueous solution) was reacted at 85 degrees C for 1.5 hours. Thereafter, in the same manner as in Synthesis Example 1, a 30 parts solution of oil-insoluble phenol resin (D) was obtained.

Synthesis Example 5 A mixture consisting of 1.0 mol of m-cresol, 1.5 mol of formaldehyde (37% aqueous solution), and 0.02 mol of magnesium hydroxide (25% aqueous solution) was reacted at 95 degrees C for 3 hours. Thereafter, in the same manner as in Synthesis Example 1, a 30 parts solution of oil-insoluble phenol resin (E) was obtained.

Example 1 Vinyrite VHC1 as a vinyl chloride copolymer resin containing carboxyl groups was added to 200 parts of a solvent consisting of methyl ethyl ketone, toluene, xylene, and diisobutyl ketone.
1 (manufactured by Union Carbide) and 4 parts of epoxy resin Epicoat 834 (Shell Chemical Co., Ltd.) were dissolved, and 26.7 parts of a 30% solution of oil-soluble phenol resin (2) obtained in Synthesis Example 1 was added. Next, vinyl chloride resin Zeon 12
1 (Nippon Zeon) and stirred and dispersed, using the same solvent as above, the viscosity was 20 seconds (Ford cup≠4.
A vinyl chloride resin organosol paint at 25 degrees Celsius was obtained.

Next, after applying a chemical conversion treatment to the inner surface of a drawn and ironed air aluminum can with an internal capacity of 350 d, the paint was applied by airless spray painting, and baked at 200 degrees C for 3 minutes,
The inner surface coating color (1
) was obtained.

Example 2 846 parts of Vinyrite VHC, 3 parts of Epicote 834,
13.3 parts of a 30% solution of oil-soluble phenolic resin (color),
A vinyl chloride resin-based organosol paint with a viscosity of 20 seconds was prepared in the same manner as in Example 1, except that 47 parts of Zeon 121 was used, and the paint was baked on an aluminized surface in the same manner as in Example 1 to form a coating with a film thickness of approximately 6 microns. Inner coating color that formed a film (2)
I got it.

Example 3 A vinyl chloride resin organosol paint was prepared in the same manner as in Example 1 except that the same amount of oil-soluble phenol resin (B) was used in place of the oil-soluble phenol resin (color), and the coating was baked on aluminium. An inner surface coating color (3) was obtained.

Example 4 A vinyl chloride resin organosol paint was prepared using the same amount of oil-soluble phenol resin (B) instead of oil-soluble phenol resin (A), and in the same manner as in Example 2.
Using this, an inner surface coating color (4) with a film thickness of about 6 microns was obtained.

Example 5 A vinyl chloride resin organosol paint was prepared in the same manner as in Example 1 except that oil-soluble phenol resin (C) was used in place of oil-soluble phenol resin (2).
Using this, inner surface coating color (5) was obtained.

Example 6 A vinyl chloride resin paint was prepared in the same manner as in Example 2, except that an oil-soluble phenol resin (C) was used instead of the oil-soluble phenol resin (T), and inner surfaces were painted using this. Color (6) was obtained.

Example 7 Vinyrite VHCI (25 parts, Vinylyte vAGIII
5 parts, 3 parts of Epicote 834, 23.3 parts of a 30% solution of oil-soluble phenolic resin (2), 50 parts of Zeon 121
A paint was prepared in the same manner as in Example 1 except that the paint was used to obtain inner surface coating color (9).

Example 8 Hinilight VHc 826 parts, Hinilight VAGI+12
1 part, 4 parts of Epicote 834, oil-soluble phenolic resin (
A paint was prepared in the same manner as in Example 1 except that 26.7 parts of a 3% solution of C) and 50 parts of Zeon 121 were used.
Using this, an inner surface coating color of 0 was obtained.

Comparative Example 1 Hinirai NlHCl 130 parts, Hinirai vAGI11
Part Q, 4 parts of Epicote 834, 23.3 parts of a 30% solution of oil-insoluble phenol resin (0), 50 parts of Zeon 121
A vinyl chloride resin-based paint was prepared in the same manner as in Example 1, except that the inner surface coating color (0) was obtained.

Comparative Example 2 An epoxy whose non-volatile components are 48 parts of Epicote 1007 (Shell Chemical Co., Ltd.), 47 parts of Epicote 1009 (the same company), and 5 parts of a resol type phenolic resin obtained by reacting bisphenol A and formaldehyde with magnesium hydroxide as a catalyst. Using phenolic resin paint (this paint is a typical epoxy phenol resin paint that has traditionally been used as the inner surface coating for general beverage cans and food cans),
It was painted in the same manner as in Example 1 and baked at 210 degrees Celsius for 3 minutes to obtain an inner surface coating color (8) with a film thickness of about 6 microns.

Comparative Example 3 A paint was prepared in the same manner as in Example 1 except that the same amount of oil-soluble phenol resin (E) was used instead of oil-soluble phenol resin (10), and this was used to obtain the inner surface coating color at. Ta.

Next, using the above-mentioned inner surface coating colors, evaluations were conducted on the following items. The results are shown in the table.

(Flavor retention) A panel evaluation of flavor based on commercially available pins of sake, wine, high-resistance beer, and beer, sealed with inner coating color and stored at 37 degrees Celsius for 3 months. The results were evaluated by 20 people on a four-level scale.

As for the can lid, an aluminum can lid whose inner surface was coated with a coating film of 12 AL using the can inner surface paint corresponding to Example 2 was used as the can lid of the inner surface coated can body.

◎ (no difference from the bottle), ○ (slight difference observed), Δ (slight difference observed), × (considerable difference observed) (0) Corrosion resistance The can filled with the above contents was opened. The state of corrosion on the inner surface of the can was observed and evaluated.

0 (no corrosion), Δ (slightly corroded) The ethanol extraction rate (100・a/a+b) was calculated by weighing the extracted it (a) and the extraction residue b) after removing aluminum from the extracted test piece (dissolving it with acid). .

As is clear from the results shown in Tables 1 and 2, the cans using the vinyl chloride resin organosol paint of the present invention have excellent quality as cans for alcoholic beverages.

(Effects of the Invention) As described above, according to the present invention, the non-volatile composition of the vinyl chloride resin organosol paint as a can inner surface paint for alcoholic beverage cans is vinyl chloride resin 3G-60 parts by weight vinyl chloride copolymer resin 30- 60 parts by weight epoxy resin
1-6 parts by weight oil-soluble phenolic resin
3-10 parts by weight, and the total amount of the epoxy resin and phenol resin is 4-16fflf of the total nonvolatile content.
fi%, and the m ratio of epoxy resin and phenolic resin is in the range of 2:1 to 1:3, so it has good workability and corrosion resistance, and there are no paint film defects such as pinholes.
It is also possible to obtain a coating that has excellent alcohol resistance and forms a coating film on the inside of a can that does not interact with the contents and does not affect the flavor of alcoholic beverages. When filled with cans, it is possible to obtain cans with excellent flavor retention.

Table-2

Claims (1)

[Claims] 1. The non-volatile composition of the vinyl chloride resin organosol paint is 30-60 parts by weight of vinyl chloride resin, 30-60 parts by weight of vinyl chloride copolymer resin, 1-6 parts by weight of epoxy resin, 3-10 parts by weight of phenol resin. The total amount of the epoxy resin and phenolic resin is 4-16% by weight of the total non-volatile content, and the weight ratio of the epoxy resin and phenolic resin is 2:1-1.
A can inner surface paint for alcoholic beverage cans, characterized in that the paint is within the range of 3 to 3. 2. The can according to item 1 above, wherein the phenol resin is a resol type phenol resin obtained by condensing at least one of P-cresol and bisphenol A with formaldehyde using an alkaline catalyst, either alone or in combination. Interior paint. 3. The number average molecular weight of epoxy resin obtained by condensation of bisphenol A and epichlorohydrin is 300-10.
00 and an epoxy equivalent of 180-500 epoxy resin. 4. The can inner surface paint according to item 1 above, wherein the vinyl chloride copolymer resin contains 50% by weight or more of a vinyl chloride-vinyl acetate copolymer having a carboxyl group. 5. A can body for an alcoholic beverage can, the inner surface of which is provided with a coating film made of the vinyl chloride resin organosol paint according to claim 1.