JPH05295319A - Resin composition for paint - Google Patents

Abstract

PURPOSE:To obtain the objective composition which has excellent workability, adhesiveness to metal, water resistance, solvent resistance, etc., and can be used for a can for food, a can for drink, a decorative can, a cap, a crown cap, etc. CONSTITUTION:This composition is prepared from 40-97wt.% aromatic epoxy resin and 60-3wt.% aromatic epoxy resin modified with an aromatic hydrocarbon/formaldehyde resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for paints used for can paints, and more particularly, it has a high processability that can be used for food cans, beverage cans, beauty cans, caps, king cans and the like. And a resin composition for coating material having metal adhesion, water resistance, solvent resistance and the like.

[0002]

2. Description of the Related Art Conventionally, metals such as aluminum, tinplate, and tin-free steel have been used as metal can materials. In order to prevent corrosion of these metals, a coating film is usually formed on the inner and outer surfaces of the can. As the can inner surface paint, epoxy-phenol resin type, epoxy-acrylic resin type and epoxy-amino resin type paints are usually used. However, the above-mentioned paints are not sufficient in corrosion resistance such as adhesion, impact resistance, water resistance, solvent resistance, etc., and their improvement is desired.

[0003]

SUMMARY OF THE INVENTION The object of the present invention is to improve various problems of conventional paints for cans, and to make them widely used as containers for foods, cosmetics and pharmaceuticals. Even after heat sterilization, the amount of water-soluble resin components present in the coating film is extremely small as an internal coating, and it is excellent in food hygiene and flavor retention, and has openability, processability, and adhesion. Another object of the present invention is to provide an excellent coating resin composition.

[0004]

Means for Solving the Problems As a result of various studies, the present inventors have found that by using a resin composition prepared by blending an aromatic epoxy resin with an aromatic hydrocarbon formaldehyde resin-modified aromatic epoxy resin. The inventors have found that the above problems can be solved and completed the present invention. That is, the present invention provides a coating resin composition (C) comprising 40 to 97% by weight of an aromatic epoxy resin (A) and 60 to 3% by weight of an aromatic hydrocarbon formaldehyde resin-modified aromatic epoxy resin (B). It is an invention related to.

Examples of the aromatic epoxy resin (A) used in the present invention include bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolac type epoxy resin, fatty acid modified epoxy resin and phenol compound modified epoxy resin. Can be mentioned. Among these aromatic epoxy resins, an average of 1.1 to 2.
Those having 0 epoxy groups and having a number average molecular weight of 2,000 or more, particularly 3,000 or more are preferable. Examples of commercially available products of the aromatic epoxy resin (A) include "Epicoat 152" and "Epicoat 15" manufactured by Shell Chemical Co., Ltd.
4 "," Epicote 1007 "," Epicote 100
9 "," Epicote 1010 "," Epicote 100 "
L] and the like. It is possible to select and use one or more kinds of aromatic epoxy resins as described above.

The aromatic hydrocarbon formaldehyde resin-modified epoxy resin (B) used in the present invention includes, for example, an aromatic hydrocarbon formaldehyde resin (B ₁ ) and an aromatic epoxy resin (B ₂ ) in diacetone alcohol, It can be obtained by dissolving in a mixed solvent such as butyl cellosolve and xylene and reacting at a temperature of 130 ° C. to 170 ° C. for 3 hours to 6 hours in the presence of an acidic catalyst. The aromatic hydrocarbon formaldehyde resin (B ₁ ) used in the present invention is obtained by reacting formaldehyde with an aromatic hydrocarbon such as toluene, xylene, mesitylene, durene, naphthalene or a mixture of various alkylbenzenes in the presence of an acid catalyst such as sulfuric acid. The aromatic hydrocarbon nucleus is a methylene bond (-CH _2- ), a methylene ether bond (-CH ₂ -O-CH _2- ), an acetal bond (-CH _2- (OCH ₂ ) nO-CH. _2- ) and a small amount of methylol group (-CH ₂ OH) and methoxy group (-
CH ₂ OCH ₃ ) having a structure having an average molecular weight of 250 to 900 and an oxygen content of 5 to 15%, which is a liquid to semi-solid pale yellow resin. These resins are usually toluene resin, xylene resin, mesitylene resin,
It is a resin called a durene resin, a naphthalene resin, an alkylbenzene resin (also called an AB resin). Examples of the aromatic epoxy resin (B ₂ ) include a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a novolac type epoxy resin, a fatty acid modified epoxy resin, and a phenolic compound modified epoxy resin. Among these aromatic epoxy resins, 1
Those having an average of 1.1 to 2.0 epoxy groups in the molecule and a number average molecular weight of 2,000 or more, particularly 3,000 or more are preferable.

Commercially available aromatic epoxy resins (B ₂ ) include "Epicoat 152" manufactured by Shell Chemical Co., Ltd.
Examples thereof include "Epicoat 154", "Epicoat 1007", "Epicoat 1009", "Epicoat 1010", "Epicoat 100L", etc. One or more kinds of aromatic epoxy resins as described above are selected. The blending ratio of the aromatic hydrocarbon formaldehyde resin (B ₁ ) and the aromatic epoxy resin (B ₂ ) is 20 parts by weight / 80 parts by weight to 80 parts by weight / 20 parts by weight, preferably 40 parts by weight. Parts / 60 parts by weight to 60 parts by weight / 40 parts by weight When the proportion of the aromatic hydrocarbon formaldehyde resin used is less than the above 20 parts by weight, the effects such as adhesion and corrosion resistance cannot be obtained, while the above When it is more than 80 parts by weight, gelation occurs during the reaction, which is not preferable.

Examples of the solvent that can be used for producing the aromatic hydrocarbon formaldehyde resin-modified epoxy resin (B) include, for example, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, isobutanol, amyl alcohol, isoamyl. Alcohols, alcohols such as sec-amyl alcohol, n-hexanol, and diacetone alcohol; glycol ethers such as methyl cellosolve, ethyl cellosolve, propyl cellosolve, butyl cellosolve, methyl carbitol, ethyl carbitol, methyl cellosolve acetate, ethyl cellosolve acetate Glycol ether acetates such as G., etc., aromatic hydrocarbons such as toluene, xylene, mesitylene, and the like, and mixtures thereof. The charging ratio of the mixture of the aromatic hydrocarbon formaldehyde resin (B ₁ ) and the aromatic epoxy resin (B ₂ ) and the above solvent is not particularly limited, but in consideration of the viscosity of the produced resin and the like 50
Part by weight / 50 parts by weight to 70 parts by weight / 30 parts by weight is preferable, and 55 parts by weight / 45 parts by weight is particularly preferable.

As the acid catalyst used in the above invention,
P-toluenesulfonic acid, organic sulfonic acids such as m-xylenesulfonic acid, and acids formed by hydration of diphosphorus pentoxide such as metaphosphoric acid, pyrophosphoric acid, orthophosphoric acid, triphosphoric acid, and tetraphosphoric acid may be mentioned. I can. The above-mentioned acid catalyst used is preferably 0.05 to 2.0% by weight in the reaction product, and particularly preferably about 0.5% by weight in consideration of reaction time and resin characteristics.

When the resin composition for paint (C) is produced, the compounding ratio is 40 to 97% by weight of the aromatic epoxy resin (A) and the aromatic hydrocarbon formaldehyde resin-modified aromatic epoxy resin (B) 60. ~ 3% by weight. When the compounding ratio of the aromatic hydrocarbon formaldehyde resin-modified aromatic epoxy resin (B) is less than the above 3% by weight, effects such as adhesion and corrosion resistance cannot be obtained, while the above 60% by weight is obtained.
If it is more than the above range, the coating film becomes too hard, and conversely the workability is deteriorated, which is not preferable. In the above range, a particularly preferable blending ratio of the aromatic hydrocarbon formaldehyde resin-modified aromatic epoxy resin (B) is 3 to 40% by weight. The coating resin composition (C) of the present invention can be heat-cured without newly adding a curing agent.
When the curing agents described in (a) to (d) are blended in a fixed proportion and used, the coating properties such as adhesion, water resistance and solvent resistance can be further improved.

(A) Curing agent (D) Examples of the phenol resin which can be used as the curing agent (D) include phenol resole, alkyl etherified phenol resole, alkylphenol resole, bisphenol A resole and the like. It is possible to use at least one or more of the above.
Specifically, the product names “METHYLON 75108” and “Methylon (METRON) manufactured by General Electric Company, USA
HYLON) 75121 ”or product names“ HITANOL 4010 ”and“ HITANOL 4020 ”manufactured by Hitachi Chemical Co., Ltd. can be exemplified. The curing agent (D) can be used in an amount of 5 to 50 parts by weight, preferably 7 to 40 parts by weight, based on 100 parts by weight of the coating resin composition (C). If the blending ratio of the curing agent (D) is less than 5% by weight, the effects such as adhesion and corrosion resistance cannot be obtained, and if it is more than 50% by weight, the coating film becomes too hard and the workability becomes poor, which is not preferable.

(B) Curing agent (E) Examples of amino resins that can be used as the curing agent (E) include alkyl etherified urea resins, alkyl etherified melamine resins, and alkyl etherified guanamine resins. It is possible to use at least one or more of the above. Specifically, Sumitomo Chemical Co., Ltd. Sumimar M40S, Dai-Nippon Ink and Chemicals Co., Ltd. Super Beckamine L-820-60, Mitsui Cyanamid Co., Ltd. Cymel 1123 and Cymel 3
03 etc. can be illustrated. The curing agent (E) can be used in an amount of 5 to 50 parts by weight, preferably 7 to 40 parts by weight, based on 100 parts by weight of the coating resin composition (C). If the mixing ratio of the curing agent (E) is less than 5 parts by weight, the effects such as adhesion and corrosion resistance cannot be obtained.
If the amount is more than 0 parts by weight, the coating film becomes too hard and the workability becomes poor, which is not preferable.

(C) Curing agent (F) As an acrylic resin which can be used as the curing agent (F), a copolymer containing 2-hydroxyethyl methacrylate, such as acrylic acid, 2-hydroxyethyl methacrylate, Examples thereof include a curing agent obtained by copolymerizing styrene, butyl acrylate, and azobisisobutyl nitrile. The curing agent (F) is the resin composition for coating (C)
5 to 50 parts by weight, preferably 7 to 100 parts by weight
40 parts by weight can be blended and used. If the mixing ratio of the curing agent (F) is less than 5 parts by weight, the effect of adhesion cannot be obtained, and if it is more than 50 parts by weight, the corrosion resistance is poor, which is not preferable.

(D) Curing agent (G) Examples of phosphoric acid that can be used as the curing agent (G) include diphosphorus pentoxide such as metaphosphoric acid, pyrophosphoric acid, orthophosphoric acid, triphosphoric acid and tetraphosphoric acid. Examples thereof include hydrated acids, and of these, one kind or a mixture of two or more kinds may be used. Further, orthophosphoric acid is particularly preferable among the above. As the acidic phosphoric acid ester, mono- and dibutyl phosphoric acid esters, mono- and hexyl phosphoric acid esters, mono- and dioctyl phosphoric acid esters and the like can also be used as phosphoric acid-based catalysts. The curing agent (G) is the resin composition for coating (C) 100
0.01 to 5 parts by weight, preferably 0.1
It can be used by blending up to 2.0 parts by weight.

The resin composition (C) for coating composition of the present invention can be used by adding a pigment, a revailing agent, an antifoaming agent and a lubricant. The coating resin composition (C) of the present invention can be applied to a substrate by a known means such as roll coating, spraying or brush coating. Examples of the base material include a metal base material such as an electric tin-plated steel plate, a tin free steer, and aluminum. The coating resin composition (C) of the present invention can be cured under a wide range of baking conditions, from baking at about 150 to 200 ° C for 20 minutes to baking at high temperature for about 20 seconds at a high temperature of about 260 ° C.

[0016]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples. In the examples, "parts" means "parts by weight". In addition, each measurement item followed the following method. (1) Gel fraction: The panel is cut into 10 cm × 10 cm and the weight W ₁ (g) is measured. MEK was added to the flask so that MEK (methyl ethyl ketone) / coated plate = 100 ml / 100 cm ² , and heated until reflux, and after starting reflux, put the coated plate and extract under MEK reflux for 2 hours. The coated plate is taken out of the flask, dried at a temperature of 150 ° C. for 30 minutes, cooled to room temperature, and the weight W ₂ (g) is measured. The coating film is stripped with a mixed solvent of MEK / cyclohexanone = 50/5 (weight ratio), dried at 150 ° C. for 30 minutes, cooled to room temperature, and the weight W ₂ (g) is measured. The gel fraction is calculated by the following formula. Gel fraction (%) = (((W ₁ -W)-(W ₁ -W ₂ )) / (W ₁ -W)) × 100 = ((W
₂ -W) / (W ₁ -W)) × 100

(2) Appearance: The surface of the film was visually observed and evaluated according to the following criteria. Absolutely no abnormalities ◎ Very slight blemishes and blurring are observed ○ Slight blemishes and glossiness are recognized ◇ Staining and glossiness are recognized △ Remarkably blemishes and glossiness are recognized × (3) Pencil hardness: JIS K-5400 I obeyed. (4) Impact resistance: Impact processing was performed from the front and back of the panel with a weight of 500 g of a hammer 3/8 ", and the height of the weight at which the film was cracked or peeled off was shown. (5) Resistance Retortability: The panel was dipped in deionized water, treated in an autoclave for 30 minutes at 125 ° C., and the whitening state of the film was observed. Also, the film of the treated panel was cut with a cutter until it reached the metal substrate. A crepe pattern (length 12 mm × width 12 mm) was formed, and then a cellophane tape was adhered to the surface thereof, and the state of adhesion of the film was observed after being rapidly separated in the direction of 180 degrees.

Example 1 Preparation of Aromatic Hydrocarbon Formaldehyde Resin-Modified Epoxy Resin Nicanol H (Mitsubishi Gas Chemical Co., Inc.) was placed in a four-necked flask equipped with a thermometer, a stirrer, a reflux condenser and a nitrogen gas blowing tube. Xylene resin product name) 500g and Epicoat 1
500 g of 007, 215 g of xylene, 215 g of diacetone alcohol, 108 g of ethyl cellosolve are charged, the temperature is raised to 100 ° C., and the mixture is uniformly dissolved with slow stirring. Then, 7 g of P-toluenesulfonic acid is added and the temperature is raised to 130 ° C. Aromatic hydrocarbon formaldehyde resin-modified epoxy resin (resin B ₁ ) is reacted for 3 hours.
Got

Example 2 Preparation of Epoxy Resin Solution In a four-necked flask equipped with a thermometer, a stirrer and a nitrogen gas blowing tube, Epicoat 1007 (500 g) and xylene were added.
215 g, diacetone alcohol 215 g, and ethyl cellosolve 108 g were charged, the temperature was raised to 100 ° C., and the mixture was uniformly dissolved with slow stirring to obtain an epoxy resin solution (resin A ₁ ).

Example 3 Preparation of Acrylic Resin Solution A four-necked flask equipped with a thermometer, a stirrer, a reflux condenser and a nitrogen gas blowing tube was charged with 100 parts of n-butanol and kept at 105 ° C. to supply nitrogen gas. A mixture of 10 parts of acrylic acid, 20 parts of 2-hydroxyethyl methacrylate, 40 parts of styrene, 30 parts of butyl acrylate, and 3 parts of azobisisobutylnitrile was added dropwise from the dropping tank over 3 hours while stirring. Then, the reaction was carried out at 105 ° C. for 1 hour to obtain an acrylic resin solution having an acid value of 70 and a number average molecular weight of 1,000.

[0021] Example 4 Resin A ₁ 20 parts, ₁ 80 parts of the resin B, Hitanoru 4020 (Hitachi Chemical Co., Ltd., trade name) 20 parts were uniformly mixed,
This mixture was applied to a 0.3 mm tin plate using a bar coater so that the film thickness when dried was 70 mg / 1000 cm ^2, and then baked at 260 ° C. for 30 seconds. An evaluation test of predetermined items was performed on the obtained coating film. The evaluation results are shown in Table 1.

Examples 5 to 9 In the same manner as described in Example 4, the curing agents shown in Table 1 were used, and tests of predetermined items were conducted. Table 1 shows the experimental conditions and the evaluation results.

Comparative Example 1 80 parts of Resin B _{1 and} 20 parts of Hitanol 4020 were uniformly mixed, and this mixture was applied to a 0.3 mm tin plate using a bar coater so that the dry film thickness would be 70 mg / 100 cm ^2. After coating, it was baked at 260 ° C. for 30 seconds. The obtained coating film was tested for predetermined items.
Table 2 shows the evaluation results. Comparative Examples 2 to 5 The curing agents shown in Table 2 were used in the same manner as described in Comparative Example 1 to carry out tests on predetermined items. Table 2 shows the experimental conditions and the evaluation results.

[0024]

[Table 1] Example 1 Example 2 Example 3 Example 4 Example 5 Resin A ₁ part 20 20 20 20 20 Resin B ₁ part 80 80 80 80 80 Curing agent part Phenolic resin 20 − − − − Amino resin − 20 − − − Acrylic resin − − 20 − − Phosphoric acid − − − 1 − Coating film thickness (mg / 100 cm ² ) 70 70 70 70 70 Evaluation result Appearance ◎ ◎ ◎ ◎ ◎ Pencil hardness (H) 3 3 3 3 3 3 Impact resistance (cm) 40 <40 <40 <40 <40 <40 <Retort resistance Appearance Good Good Good Good Good Good Adhesiveness Good Good Good Good Good Curing condition is 260 ° C. for 30 minutes. Curing agent in the table Phenol resin: Hitanol 4020 Amino resin: Super Peckamine L-820-60 Acrylic resin: Synthesized in Example 3 Phosphoric acid: 10% Orthophosphoric acid

[0025]

[Table 2] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Resin B ₁ part 80 80 80 80 80 Curing agent part Phenolic resin 20 − − − − Amino resin − 20 − − − Acrylic resin − − 20 − − Phosphoric acid − − − 1 − Coating film thickness (mg / 100 cm ² ) 70 70 70 70 70 Evaluation results Appearance ○ ◇ ◇ △ △ Pencil hardness 2H 2H 2H H B Impact resistance (cm) 30 30 30 10 10 Resistance Retortability Appearance Whitening Whitening Whitening Whitening Whitening Adhesion Good Deterioration Deterioration Deterioration Curing conditions are 260 ° C for 30 minutes. Curing agent in the table Phenol resin: Hitanol 4020 Amino resin: Super Peckamine L-820-60 Acrylic resin: Synthesized in Example 3 Phosphoric acid: 10% Orthophosphoric acid

[0026]

EFFECTS OF THE INVENTION By using the resin composition (C) for paint of the present invention as an inner surface paint of a metal container which is widely used as a container for foods, cosmetics, pharmaceuticals, etc., after heat sterilization treatment, In addition, the amount of water-soluble resin component existing in the coating film is extremely small, and food hygiene,
It is possible to obtain a coating film having excellent flavor retention, openability, processability, and adhesion.

Claims (5)

[Claims] 1. Aromatic epoxy resin (A) 40-97
A coating resin composition (C) comprising 60% by weight and 60% by weight of an aromatic hydrocarbon formaldehyde resin-modified aromatic epoxy resin (B). 2. When curing the coating resin composition (C), 5 to 50 parts by weight of a phenol resin is blended as a curing agent (D) with 100 parts by weight of the coating resin composition (C). The coating resin composition according to claim 1. 3. When curing the coating resin composition (C), 5 to 50 parts by weight of an amino resin as a curing agent (E) is added to 100 parts by weight of the coating resin composition (C). Item 1. A resin composition for paint according to item 1. 4. When curing the coating resin composition (C), 5 to 50 parts by weight of an acrylic resin is mixed as a curing agent (F) with 100 parts by weight of the coating resin composition (C). Item 1. A resin composition for paint according to item 1. 5. When curing the coating resin composition (C), from 100 parts by weight of the coating resin composition (C), a curing agent and a curing accelerator (G) are selected from phosphoric acid and an acidic phosphate ester. 0.01-5 at least one selected
The coating resin composition according to claim 1, wherein the resin composition is mixed in parts by weight.