JP2003119246A - New epoxy resin, its production method and coating resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new epoxy resin having a reduced amount of bisphenol to be generated by decomposition on heating, a method for producing the same, and a coating composition which reduces the staining of a baking oven due to the inclusion of the resin therein and, simultaneously, reduces the migration of bisphenols into the contents, and is particularly suited in use for food containers and tubes for water service. SOLUTION: The epoxy resin is produced by reacting a bisphenol type epoxy resin having an epoxy equivalent weight of 170-1,000 g/eq, a specified compound and, if necessary, a bisphenol. Further, the coating resin composition comprises the resin.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a new and useful epoxy resin, a method for producing the same, and a resin composition for paints. More specifically, the present invention provides an epoxy resin having a specific terminal group structure, which reduces bisphenols generated by thermal decomposition during baking, a method for producing the same, and a resin composition for paints.

[0002]

2. Description of the Prior Art Epoxy resins are today known for their excellent physical properties,
Due to its chemical nature, it is used in a variety of applications such as civil engineering / construction, adhesion, paint, electrical / electronics. In particular, a baking type paint in which a curing agent is blended with a bisphenol type epoxy resin having a number average molecular weight of 1,000 to 20,000 forms a coating film excellent in adhesion with metal, water resistance and chemical resistance, and therefore, it is a metal. It is widely used as a paint on the inside and outside of pipes, PCM paint, and inside and outside paints for food and beverage cans. These paints are 160
Since baking is performed at a high temperature of 250 to 250 ° C., the generation of bisphenols due to thermal decomposition of the epoxy resin poses a problem. Bisphenols generated by thermal decomposition at the time of baking become fumes and cause pollution of the baking furnace. In addition, from the viewpoint of hygiene, in the application fields of water and sewer pipes, food cans, beverage cans, etc., there is a demand for an epoxy resin with less migration of bisphenol A to the contents and a resin composition for its coating. The bisphenol type epoxy resin is oxidized at a high temperature of about 170 ° C. and undergoes radical decomposition to generate bisphenols. It is generally known that the addition of a phenol-based, sulfur-based, or phosphorus-based compound having a radical scavenging ability reduces the amount of bisphenols decomposed by heat. For example, Japanese Unexamined Patent Publication No. 2000-226542 proposes an aqueous resin composition for can coating in which bisphenol A is little eluted by adding an antioxidant to a carboxyl group-containing self-emulsifying epoxy resin. In addition, JP 2000-2
Japanese Patent No. 732282 proposes an epoxy resin composition in which bisphenol A generated during heating is reduced by adding a thermal decomposition inhibitor. Although the amount of bisphenol A eluted and the amount of bisphenol A produced are all reduced, the addition of relatively low molecular weight antioxidants and thermal decomposition inhibitors causes the additives themselves to volatilize during baking, and In addition to causing contamination, if it remains in the coating film,
There are problems that the physical properties of the coating film are deteriorated and that the substance moves into contact with the coating film.

[0003]

DISCLOSURE OF THE INVENTION The present invention is to provide a novel epoxy resin in which bisphenols generated by thermal decomposition are reduced. When the epoxy resin is contained, the epoxy resin is decomposed during baking. It is an object of the present invention to provide a resin composition for coatings, which has a small amount of bisphenol and in which the migration of bisphenols to the substance that comes into contact with the obtained coating film is small.

[0004]

Means for Solving the Problems As a result of earnest studies on a method for preventing thermal decomposition of an epoxy resin, the present inventors have found that by introducing a specific functional group at the molecular end of the epoxy resin, bisphenol generated at the time of heating. The inventors have found that the amount is suppressed and have reached the present invention. The present invention includes the following inventions. (1) contains 0.005 to 10% by weight of the terminal group represented by the general formula (1), and has a number average molecular weight of 1,000.
To 20,000, and a bisphenol type epoxy resin (A).

[0005]

[Chemical 3]

(In the formula, R ₁ and R ₂ are each an alkyl group having 1 to 5 carbon atoms and may be the same or different.)

(2) Epoxy equivalent 170 to 1.00
Bisphenol type epoxy resin (a) with 0 g / eq
And at least one selected from the compounds represented by the general formula (2) and, if necessary, bisphenols are reacted to obtain the epoxy resin (A) according to the above (1). Production method.

[0008]

[Chemical 4]

(In the formula, R ₁ and R ₂ are each an alkyl group having 1 to 5 carbon atoms and may be the same or different.)

(3) The bisphenol type epoxy resin (a) is a bisphenol A type epoxy resin, the bisphenols are bisphenol A, and the general formula (2)
The epoxy resin (A) according to (2) above, wherein the compound represented by the formula is 2,5-di-tert-butylhydroquinone.
Manufacturing method. (4) A method for purifying an epoxy resin (A), which comprises removing the unreacted bisphenols by post-treating the epoxy resin (A) with an alkali metal hydroxide and water. (5) A resin composition for coating composition, which comprises the epoxy resin (A) according to any one of (1) to (4) and a curing agent for an epoxy resin. (6) The solvent-based or water-based coating resin composition, wherein the curing agent for an epoxy resin according to the above (5) is at least one cross-linking agent selected from an amino resin and a resole-type phenol resin. .

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The novel terminal-modified epoxy resin (A) of the present invention has an epoxy equivalent of 170 to 1,000.
Obtained by reacting g / eq of a bisphenol type epoxy resin (a) with at least one selected from the compounds represented by the formula (2) and, if necessary, a bisphenol in the presence of a catalyst. You can

The bisphenol type epoxy resin (a) having an epoxy equivalent of 170 to 1,000 g / eq used in the present invention is bisphenol A type or bisphenol F type.
Type, bisphenol AD type, bisphenol C type, bisphenol S type, bisphenol E type, bisphenol B type and epoxy resins obtained by mixing two or more of these, but are not limited to these. Among these, bisphenol A type epoxy resin is preferable. Examples of the compound of formula (2) that can be used in the present invention include 2,5
-Di-tert-amylhydroquinone, 2,5-di-
tert-butyl hydroquinone, 2,5-di-sec
-Butyl hydroquinone, 2,5-diethyl hydroquinone, 2,5-dimethyl hydroquinone and the like can be mentioned, but the present invention is not limited thereto. These compounds may be used alone or in combination of two or more, but 2,5-di-
Especially preferred is tert-butyl hydroquinone. The amount of the compound of the formula (2) used is 0.00 based on the epoxy resin.
It is preferably 5 to 10% by weight.

When producing the epoxy resin (A) of the present invention, the molecular weight can be adjusted by reacting bisphenols at the same time. Examples of usable bisphenols include bisphenol A, bisphenol F, bisphenol AD, bisphenol C, bisphenol S,
Examples thereof include bisphenol E, bisphenol B, and a mixture of two or more thereof, but are not limited thereto. Among these, bisphenol A and bisphenol F are preferable. The amount of bisphenols used is appropriately determined according to the molecular weight of the epoxy resin used as the raw material and the target molecular weight, but is 3 with respect to the raw epoxy resin.
To 60% by weight. The reaction temperature and reaction time are preferably determined appropriately so that the amount of bisphenol in the reaction product resin is 10 ppm or less, preferably 1 ppm or less, and usually 30 to 20 minutes at 60 to 220 ° C.
It is a range of time. Bisphenol content is 10ppm
In the above cases, the unreacted bisphenols can be transferred to the alkaline metal hydroxide aqueous solution and removed by being brought into contact with the alkaline metal hydroxide aqueous solution.

As the catalyst that can be used in the production of the epoxy resin (A) of the present invention, alkali metal hydroxides such as caustic soda and caustic potash, triethylamine, tri-
Tertiary amines such as n-butylamine, imidazoles such as 2-methylimidazole and 2-ethyl-4-methylimidazole, phosphines such as triphenylphosphine, quaternary ammonium salts such as tetraethylammonium bromide and benzyltrimethylammonium chloride. , N-butyltriphenylphosphonium bromide, ethyltriphenylphosphonium iodide, and the like, but are not limited thereto. These catalysts may be used alone or in combination of two or more, if necessary, and the amount thereof used is in the range of 0.005 to 3% by weight based on the epoxy resin depending on the kind of the catalyst.

When producing the epoxy resin (A) of the present invention, a solvent can be used if necessary. As the solvent that can be used, aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene, alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, secondary butanol, and tertiary butanol, acetone. , Ketones such as methyl ethyl ketone, dimethyl ketone, methyl isobutyl ketone, cyclohexanone, ethyl acetate, butyl acetate, esters such as ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, methyl cellosolve, ethyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether Etc., glycol ethers, dioxane, trioxane, etc. cyclic ethers, ethylene glycol dimethyl ether, die Chain ethers such as glycol dimethyl ether, N, N-dimethylformamide, N, N
-Dimethylacetamide, N-methylimidazolidinone, N-methylpyrrolidone and the like can be mentioned, but not limited thereto. Further, these solvents may be used alone or in combination of two or more.

The amount of the terminal group represented by the general formula (1) in the novel epoxy resin of the present invention is preferably 0.005 to 10% by weight. When the amount of terminal groups is less than 0.005% by weight, the effect of reducing bisphenol A generated during heating does not appear,
This is because the adhesiveness of the coating film decreases if the content is 10% by weight or more. The amount of end groups is determined by proton nuclear magnetic resonance spectroscopy (1H-
It can be quantified by NMR). For example, as the compound represented by the general formula (2), 2,5-di-tert-
When butyl hydroquinone is used, it can be quantified from the ratio of the peak area derived from the aromatic hydrogen to the peak area derived from the aromatic hydrogen indicated by the arrow in the formula (3) near δ 6.48.

[0017]

[Chemical 5]

The number average molecular weight of the novel epoxy resin in the present invention is preferably 1,000 to 20,000. The number average molecular weight is measured by gel permeation chromatography (GPC) and calculated in terms of polystyrene. This is because when the number average molecular weight is less than 1,000, when the coating composition is used, the bending workability of the coating film is insufficient, and when it exceeds 20,000, the adhesiveness decreases.

The novel bisphenol type epoxy resin (A) having a modified terminal group according to the present invention is cured with a curing agent in the same manner as a usual bisphenol type epoxy resin.
Examples of the curing agent for the bisphenol type epoxy resin (A) according to the present invention include aliphatic polyamines, polyamidoamines which are condensation polymerization products of aliphatic polyamines and dimer acids, aromatic amines, acid anhydrides, Usual isocyanates, blocked isocyanates, dibasic acid dihydrazides, acid-terminated polyesters, mercapto-terminated polysulfides, imidazoles, boron trifluoride amine complexes, dicyandiamide, resole phenolic resins, amino resins, etc. Examples thereof include curing agents for bisphenol type epoxy resins, with resole phenol resins and amino resins being particularly preferable. Examples of the resol resin include condensates of phenols, alkylphenols, bisphenols and aldehydes such as formaldehyde and acetaldehyde under a basic catalyst, and their alkyl ethers such as methanol, ethanol, n-butanol and isobutanol. Can be mentioned. On the other hand, examples of the amino resin include condensates of urea, melamine, benzoguanamine and the like with aldehydes and the like under a basic catalyst, and alkyl ethers of the above-mentioned alcohols and the like.

The bisphenol type epoxy resin (A) according to the present invention is used as a resin composition containing the resin in coating compositions, adhesives and the like. Particularly, the bisphenol type epoxy resin (A) according to the present invention is used. ) Is controlled to reduce the amount of bisphenol A generated by thermal decomposition, and is effective in preventing contamination in the baking oven. Further, a coating film containing the epoxy resin (A) has a migration rate of bisphenol A. It is preferable as a coating composition because it has a small amount. In the coating composition according to the present invention, one kind of the above-mentioned curing agents may be used, or two or more kinds may be mixed and used if necessary. Further, the compounding amount thereof is in the range of 1 to 50% by weight based on the total amount of the composition. The coating composition in the present invention can be used as a powder coating or, if necessary, as a varnish type coating dissolved in a solvent. The solvent that can be used in the varnish type paint is not particularly limited as long as it can uniformly dissolve the paint composition. Further, the coating composition of the present invention is a known method, for example, a method of partially esterifying the bisphenol type epoxy resin (A) with an acrylic resin containing a carboxyl group in the presence of an esterification catalyst, or a carboxyl group. The self-emulsifying resin can be used by being dispersed in water by a method such as copolymerization in the presence of a group-containing unsaturated monomer and a free radical generator. The coating composition of the present invention may optionally use a reaction accelerator such as phosphoric acid or paratoluene sulfonic acid, and if necessary, various additives used in ordinary epoxy resin coatings, for example, Fillers, reinforcing agents, pigments, flow control agents, surface control agents and the like can be added. As a method for coating using the coating composition of the present invention, spray, roll coating, brush coating,
Known methods such as flow coating and electrostatic coating can be used, and a coating film can be obtained by baking at a temperature of 120 to 300 ° C. for 30 seconds to 20 minutes.

[0021]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In addition, "part", "%", "ppm", and "ppb" represent a weight part, weight%, weight ppm, and weight ppb, respectively. Example 1 1 L equipped with a thermometer, a stirrer, a cooling tube and a nitrogen introducing tube
Epototo YD-12 in a glass separable flask
8 (BTO type liquid epoxy resin manufactured by Tohto Kasei Co., Ltd., epoxy equivalent 187 g / eq): 500 parts, bisphenol A: 260 parts, 2,5-di-tert-butylhydroquinone: 0.4 parts and n-butyltriphenyl. Phosphonium bromide: 0.5 part was charged, under a nitrogen atmosphere,
While stirring, the temperature was raised to 200 ° C. and the reaction was carried out for 5 hours.
Extract the reaction product into an aluminum dish and use an epoxy equivalent of 2, 1
An epoxy resin (A-1) having 50 g / eq, a number average molecular weight of 6,200, a bisphenol A content of 0.7 ppm and an end group of 350 ppm derived from 2,5-di-tert-butylhydroquinone was obtained. (A-1) 0.2 g was accurately weighed in a 20 ml volumetric flask, sealed and heat-treated in a hot air circulation oven maintained at 230 ° C. for 1 hour. After the heat treatment, the product was taken out from the oven, cooled, dissolved in THF and measured. The concentration of bisphenol A per resin in this solution was measured by the reverse phase HPLC / fluorescence method. The amount of bisphenol A before heat treatment was subtracted to obtain the amount of bisphenol A generated during heating. The amount of 2,5-di-tert-butylhydroquinone was also measured. The results are shown in Table 1.

Example 2 3 L equipped with a thermometer, stirrer, cooling tube and nitrogen introducing tube
Epototo YD-12 in a glass separable flask
8: 300 parts, bisphenol A: 181 parts, 2,5-
Di-tert-butylhydroquinone: 1 part, 49% caustic soda aqueous solution: 4 parts, toluene: 1200 parts and n-
Butanol: 600 parts was charged, and the mixture was heated to 80 ° C. with stirring under a nitrogen atmosphere and reacted for 15 hours. After completion of the reaction, add 3 parts of the resin solution with 300 parts of a 1% sodium hydroxide solution.
Washed twice and unreacted bisphenol A and 2,5-di-t
The ert-butyl hydroquinone was removed. Then 3
It was washed several times with 00 parts of hot water and repeated until the washing water became neutral. From this solution under reduced pressure of 5 mmHg, 20
Toluene and n-butanol were removed by heating at 0 ° C, the number average molecular weight was 14,500, and the bisphenol A content was 0.9.
An epoxy resin (A-2) having an end group of 500 ppm of 2,5-di-tert-butylhydroquinone of 500 ppm was obtained. (A-2) was operated in the same manner as in Example 1 to measure the amount of bisphenol A generated during heating and the amount of 2,5-di-tert-butylhydroquinone. The results are shown in Table 1.

Example 3 Epototo YD-128: 3 was used in the same apparatus as in Example 1.
00 parts, bisphenol A: 200 parts, 2,5-di-t
ert-Butyl hydroquinone: 1 part and n-butyltriphenylphosphonium bromide: 0.4 part were charged, and the mixture was heated to 200 ° C. under stirring in a nitrogen atmosphere and reacted for 5 hours. Extract the reaction product into an aluminum dish,
Epoxy equivalent 810 g / eq, number average molecular weight 2,12
0, bisphenol A content 0.2 ppm, 2,5-di-
tert-Butyl hydroquinone-derived terminal group 1,00
0 ppm of epoxy resin (A-3) was obtained. (A-3)
In the same manner as in Example 1, the amount of bisphenol A generated during heating and the amount of 2,5-di-tert-butylhydroquinone were measured. The results are shown in Table 1.

Comparative Example 1 The same operation as in Example 1 was carried out except that 2,5-di-tert-butylhydroquinone was not used, and the epoxy equivalent was 2,100 g / eq, the number average molecular weight was 6,100, and the bisphenol A content was 0. 6 ppm epoxy resin (B-1)
Got (B-1) was operated in the same manner as in Example 1 to measure the amount of bisphenol A generated during heating and the amount of 2,5-di-tert-butylhydroquinone. The results are shown in Table 1.

Comparative Example 2 The same operation as in Example 2 was repeated except that 2,5-di-tert-butylhydroquinone was not used, and the number average molecular weight was 1
An epoxy resin (B-2) having 4,700 and a bisphenol A content of 0.9 ppm was obtained. For (B-2), the same operation as in Example 1 was performed, and the amount of bisphenol A generated during heating was 2, 5,
-The amount of di-tert-butylhydroquinone was measured.
The results are shown in Table 1.

Comparative Example 3 Epoxy equivalent 8 was obtained by the same procedure as in Example 3 except that 2,5-di-tert-butylhydroquinone was not used.
An epoxy resin (B-3) having 00 g / eq, a number average molecular weight of 2,200 and a bisphenol A content of 0.2 ppm was obtained. (B-3) was operated in the same manner as in Example 1 to measure the amount of bisphenol A generated during heating and the amount of 2,5-di-tert-butylhydroquinone. The results are shown in Table 1.

Comparative Example 4 Epotote YD-909 (BPA type solid epoxy resin manufactured by Tohto Kasei Co., Ltd., epoxy equivalent 2,150 g / eq, number average molecular weight 6,200, bisphenol A content 2 ppm) was used in the same apparatus as in Example 1. Charge 500 parts,
It was heated and melted in a nitrogen atmosphere. 2,5-
Di-tert-butylhydroquinone: 0.25 part was added, and the mixture was stirred and mixed at 180 ° C. for 1 hour, then extracted into an aluminum dish, and an epoxy resin having an epoxy equivalent of 2,220 g / eq and a number average molecular weight of 6,300 (B- 4) was obtained. (B-
4) was operated in the same manner as in Example 1 to measure the amount of bisphenol A generated during heating and the amount of 2,5-di-tert-butylhydroquinone. The results are shown in Table 1.

[0028]

[Table 1]

Example 4 100 parts of each of the epoxy resins (A-1) and (A-2) obtained in Examples 1 and 2, 200 parts of cyclohexanone and 100 parts of xylene were charged and dissolved in the same apparatus as in Example 1. To give a solution having a resin concentration of 25%. To this solution, 48 parts of HITANOL 4010 (Resole type phenol resin manufactured by Hitachi Chemical Co., Ltd., resin concentration 50%) and 0.5 part of 85% phosphoric acid were added and stirred to obtain a uniform epoxyphenol coating composition (P-1), (P-2) was obtained. (P-1),
0.2 g of each of (P-2) in a 20 ml volumetric flask
Was accurately weighed and heat-treated for 1 hour in a hot air circulating oven maintained at 230 ° C. After the heat treatment, the product was taken out of the oven, cooled, made up with THF and allowed to stand at room temperature for 24 hours. The solution was filtered and the concentration of bisphenol A generated per coating solid content was measured by a reverse phase HPLC / fluorescence method. The results are shown in Table 2. Apply (P-1) and (P-2) to an aluminum plate having a thickness of 0.3 mm, respectively.
It was baked at 0 ° C. for 10 minutes to obtain a coating film test plate having a film thickness of 10 μm. Put the test plate in a pressure glass vessel, after the contact ratio of the coating film surface and water was sealed addition of ion-exchanged water so that 1 cm ^2/1 ml, at 125 ° C. at a retort sterilizer 3
A 0 minute extraction process was performed. The extracted water after cooling was measured by gas chromatography-mass spectrometry. The results are shown in Table 3.

Example 5 100 parts of each of the epoxy resins (A-1) and (A-2) obtained in Examples 1 and 2, 200 parts of cyclohexanone and 100 parts of xylene were charged and dissolved in the same apparatus as in Example 1. To give a solution having a resin concentration of 25%. To this solution, 10 parts of Cymel 303 (a melamine resin manufactured by Mitsui Cyanamid Co., Ltd.) and 0.2 part of 85% phosphoric acid were added and stirred to give a uniform aminoepoxy resin composition (P-3), (P-4).
Got For (P-3) and (P-4), the generated bisphenol A concentration was measured by the same operation as in Example 4. The results are shown in Table 2. Further, (P-3) and (P-4) were subjected to the same operations as in Example 4 to prepare a coated plate and measure the amount of bisphenol A in the extracted water. The results are shown in Table 3.

Example 6 (A-3): 100 parts, Curezol 2PZ (2-phenylimidazole manufactured by Shikoku Chemicals Co., Ltd.): 2 parts, titanium oxide: 5 parts, silica: 30 parts and acronal 4F.
(Polyacrylate flow control agent manufactured by BASF Japan Ltd.): 1 part was premixed with a super mixer and then melt-kneaded at 110 ° C. with a uniaxial extruder to form pellets. Coarse particles obtained by finely pulverizing the pellets with an ACM palpelizer are classified with a sieve to have an average particle size of 50 μm.
To obtain a powder coating (P-5). (P-5) was treated in the same manner as in Example 4 to measure the concentration of generated bisphenol A. The results are shown in Table 2.

Comparative Example 5 Epoxy phenol coating compositions (P-6) and (P-7) were prepared in the same manner as in Example 3, except that the epoxy resins (B-1) and (B-2) were used. Obtained. (P-6), (P-
7) was treated in the same manner as in Example 4 to measure the amount of bisphenol A generated and the amount of extracted bisphenol A. The results are shown in Tables 2 and 3.

Comparative Example 6 Aminoepoxy resin compositions (P-8) and (P-9) were prepared in the same manner as in Example 4 except that the epoxy resins (B-1) and (B-2) were used. Obtained. (P-8), (P-
9) was treated in the same manner as in Example 4 to measure the amount of bisphenol A generated and the amount of extracted bisphenol A. The results are shown in Tables 2 and 3.

Comparative Example 7 A powder coating material (P-10) was obtained in the same manner as in Example 5 except that the epoxy resin (B-3) was used. (P-1
0) was subjected to the same operation as in Example 4 to measure the generated bisphenol A concentration. The results are shown in Table 2.

[0035]

[Table 2]

[0036]

[Table 3]

Example 7 An epoxy resin (A-2) 150 was added to the same apparatus as in Example 1.
Parts and 120 parts of n-butanol were charged and dissolved by heating with stirring. Add 25 parts of methacrylic acid, 11 parts of styrene, 1 part of ethyl acrylate, 3 parts of benzoyl peroxide to this solution.
1 part in a flask with a mixture of 10 parts and 10 parts of n-butanol.
The solution was added dropwise over 2 hours while maintaining it at 20 ° C. After the dropping was completed, the reaction was further performed at 120 ° C. for 2 hours to obtain an acrylic modified epoxy resin. 100 parts of the above acrylic modified epoxy resin was charged into a four-necked flask and heated to 100 ° C.
Heat with stirring until dimethylethanolamine 4
Part and 260 parts of ion-exchanged water were added dropwise over 30 minutes. Further, 130 parts of an azeotropic mixture of n-butanol and water was distilled off under reduced pressure to obtain an acrylic modified epoxy resin aqueous dispersion having a resin concentration of 25%. To 100 parts of this acrylic-modified epoxy resin water dispersion, 10 parts of Hitanol 7007H (Hitachi Chemical Co., Ltd. water-based resol-type phenol resin, solid content 40%) was mixed, and the desired water-based epoxy phenol coating composition (P-10). Got The coating composition (P-10) was used to prepare a coating film test plate and extract the retort in the same manner as in Example 4, and the results are shown in Table 4.

Comparative Example 8 The same procedure as in Example 8 was carried out except that the epoxy resin (B-2) was used, and the water-based epoxy phenol coating composition (P
-11) was obtained. The coating composition (P-11) was used to prepare a coating film test plate and extract the retort in the same manner as in Example 4, and the results are shown in Table 4.

[0039]

[Table 4]

[0040]

INDUSTRIAL APPLICABILITY The novel epoxy resin of the present invention and the coating composition containing the resin are controlled so that the amount of bisphenol A generated by decomposition when heated is small and very useful for preventing contamination in the baking oven. Is. In addition, the coating composition has little migration of bisphenol A to the contents, and is particularly useful as a coating agent used for food containers.

Continued front page    (72) Inventor Hiroshi Nakagaki             3-17-14 Higashikasai, Edogawa-ku, Tokyo Tohka             Sei product Co., Ltd. F term (reference) 4J036 AA01 AD01 CA08 JA01 KA01                 4J038 DA062 DA142 DA152 DB061                       DB141 GA07 KA03 MA07                       PA19

Claims (6)

[Claims] 1. A terminal group represented by the general formula (1) is 0.0
It is contained in an amount of 05 to 10% by weight and has a number average molecular weight of 1,
Bisphenol-type epoxy resin (A), which is 000 to 20,000. [Chemical 1] (In the formula, R ₁ and R ₂ are each an alkyl group having 1 to 5 carbon atoms and may be the same or different) 2. Epoxy equivalent of 170 to 1,000 g /
A bisphenol type epoxy resin (a) which is eq and at least one selected from the compounds represented by the general formula (2) and, if necessary, bisphenols are obtained by reaction. 1. The method for producing the epoxy resin (A) according to 1. [Chemical 2] (R ₁ and R ₂ are each an alkyl group having 1 to 5 carbon atoms and may be the same or different) 3. The bisphenol type epoxy resin (a) is a bisphenol A type epoxy resin, the bisphenol is bisphenol A, and the compound represented by the general formula (2) is 2,5-di-tert-butylhydroquinone. The method for producing an epoxy resin (A) according to claim 2, wherein 4. A method for purifying an epoxy resin (A), which comprises removing the unreacted bisphenols by post-treatment of the epoxy resin (A) with an alkali metal hydroxide and water. 5. A resin composition for coating composition, which comprises the epoxy resin (A) according to any one of claims 1 to 4 and a curing agent for epoxy resin. 6. The solvent-based or water-based coating resin composition, wherein the epoxy resin curing agent according to claim 5 is at least one cross-linking agent selected from amino resins and resol-type phenol resins. object.