Amin-modified phenol novolak resin

Abstract

To provide an amine-modified phenolic resin that has excellent solubility in acidic aqueous solution and yields a cured product having better solvent resistance than conventional amine-modified phenolic resin, and to provide a method for producing the same.SOLUTION: Provided is an amine modified phenol novolak resin that is a reaction product of a novolac-type phenolic resin represented by the following general formula (1), formaldehyde, and amine. In the general formula (1), n is 0 or a positive integer, and the total area of a n=0 component and a n=1 component to the area of the whole novolak-type phenolic resin in gel permeation chromatography analysis is 10 area % or more and 20 area % or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an amine-modified phenolic novolak resin.

Background Art

[0002] Since phenolic resins are excellent in corrosion resistance, adhesion, and heat resistance, they are widely used as raw materials for paints and adhesives, precursors and curing agents for epoxy resins.

[0003] From the perspective of environmental issues such as recent VOC reduction, the water-based conversion of paint and adhesive compositions has been actively studied, and the demand for water-based phenolic resins has been increasing. Amine-modified phenolic resins obtained by introducing aminomethyl groups into phenolic resins are water-soluble phenolic resins and have excellent corrosion resistance and adhesion. Therefore, their use in metal surface treatment agents (chemical conversion treatment agents), binders for electrodeposition paints, water-based paint additives, etc. has been proposed (Patent Documents 1 to 4).

[0004] In recent years, a composition consisting of an amine-modified phenolic resin, phosphoric acid, and a chromium fluoride compound has been used as a chemical conversion treatment agent for metal foils used in laminated bodies for the exterior of secondary batteries such as lithium-ion batteries (Patent Document 5).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, the cured product obtained from the conventional composition containing an amine-modified phenol resin has a problem that its resistance to organic solvents is not sufficient. Particularly in a lithium-ion battery which is a non-aqueous battery, in order to maintain the adhesion at the interface of the laminated film forming the exterior body, an improvement in resistance to an alkyl carbonate compound which is an electrolytic solution and corrosion resistance to hydrofluoric acid which is a hydrolysis product of a fluorine-based electrolyte is strongly required.

[0007] An object of the present invention is to provide an amine-modified phenol resin and a method for producing the same, which are excellent in solubility in an acidic aqueous solution and can obtain a cured product having solvent resistance superior to that of conventional amine-modified phenol resins.

Means for Solving the Problems

[0008] As a result of intensive studies to solve the above problems, the present inventors have found that an amine-modified phenol novolak resin which is a reaction product of a novolak-type phenol resin having a specific molecular weight distribution, formaldehyde, and amines is excellent in solubility in an acidic aqueous solution and can obtain a cured product having excellent solvent resistance, and have completed the present invention.

[0009] The present invention is an amine-modified phenol novolak resin which is a reaction product of a novolak-type phenol resin represented by the following general formula (1), formaldehyde, and amines.

[0010]

Chemical formula

[0011] The present invention also relates to a method for producing an amine-modified phenol novolak resin by reacting a novolak-type phenol resin represented by the above general formula (1), formaldehyde, and amines.

Advantages of the Invention

[0012] The amine-modified phenol novolak resin of the present invention is excellent in solubility in an acidic aqueous solution, and a cured product having solvent resistance superior to that of conventional amine-modified phenol resins can be obtained. Therefore, the amine-modified phenol novolak resin of the present invention can be suitably used as a resin component of a metal surface treatment agent.

Embodiments for Carrying Out the Invention

[0013] The amine-modified phenol novolak resin of the present invention is an amine-modified phenol novolak resin which is a reaction product of a novolak-type phenol resin represented by the following general formula (1) (hereinafter also referred to as "novolak-type phenol resin (1)"), formaldehyde, and amines.

[0014]

Chemical Formula

[0015] The amine-modified phenol novolak resin of the present invention is obtained by introducing amino groups by reacting a novolak-type phenol resin having a specific molecular weight distribution with formaldehyde and amines, and one of its characteristics is having a specific molecular weight distribution. The measurement of the molecular weight distribution is generally carried out by gel permeation chromatography (GPC) analysis. However, due to the interaction between the amino groups introduced into the resin and the polar groups of the filler, the resin is adsorbed on the column, making it difficult to accurately grasp the molecular weight distribution of the resin. Therefore, the molecular weight distribution of the amine-modified phenol novolak resin of the present invention cannot be directly specified by a general method and has to be specified by the molecular weight distribution and production method of the novolak-type phenol resin as the raw material. Therefore, regarding the amine-modified phenol novolak resin of the present invention, there is a situation where it is impossible to directly specify the substance by its structure or properties at the time of filing, or it is not approximately practical.

[0016] In the present invention, the novolak-type phenol resin (1) has a specific molecular weight distribution. Specifically, it is characterized in that the total area of the component with n = 0 and the component with n = 1 with respect to the total area of the entire novolak-type phenol resin in gel permeation chromatograph analysis is within a specific range. The total area of the component with n = 0 and the component with n = 1 is preferably 10 area% or more and 20 area% or less, more preferably 11 area% or more and 18 area% or less, and particularly preferably 12 area% or more and 16 area% or less. By setting the total area of the component with n = 0 and the component with n = 1 within the above range, an amine-modified phenol novolak resin that forms a cured film with high solvent resistance when cured after film formation can be obtained.

[0017] In the present invention, the molecular weight distribution of the novolak type phenol resin (1) is such that the total area of the component with n = 0 and the component with n = 1 with respect to the total area of the novolak type phenol resin in gel permeation chromatograph analysis is within a specific range, and more preferably, the area of the n = 2 component is within a specific range. The area of the n = 2 component is preferably 15 area % or more and 45 area % or less, and more preferably 20 area % or more and 40 area % or less. By setting the area of the n = 2 component within the above range, an amine-modified phenol novolak resin that forms a cured film having high solvent resistance when cured after film formation can be obtained, and the viscosity of the amine-modified phenol novolak resin can be easily reduced to a low viscosity.

[0018] As the formaldehyde, for example, aqueous formaldehyde (formalin) can be preferably used. As the formaldehyde-generating substance, compounds that generate formaldehyde such as paraformaldehyde, trioxane, and tetraoxane can be preferably used.

[0019] The above amines mean compounds having an amino group, and examples thereof include compounds represented by the following general formula (2).

[0020]

Chemical formula

[0021] Specific examples of the above amines include propylamine, isopropylamine, butylamine, monoethanolamine, diethanolamine, N-methylethanolamine, propanolamine, isopropanolamine, and diisopropanolamine.

[0022] The amine-modified phenol novolak resin of the present invention is a reaction product of a novolak-type phenol resin (1), formaldehyde, and amines. For example, it can be produced by reacting 0.5 to 1.5 moles of amines and the same molar amount of formaldehyde as the amines with respect to 1 mole of the phenol ring present in the structure of the novolak-type phenol resin (1).

[0023] The reaction may be carried out under conditions where the reaction is completed. For example, the novolak-type phenol resin (1) and amines are dissolved in a solvent, and an aqueous formaldehyde solution (formalin) is sequentially added dropwise to the resulting solution over 10 to 120 minutes, and then heated at 50 to 120 °C for 1 to 12 hours. Thereby, an amino group can be introduced into the phenol ring.

[0024] The amount of amines used in the reaction may be appropriately adjusted so that the amount of amino groups introduced into the phenol ring becomes a desired amount. However, it is preferably 0.5 to 1.5 moles, more preferably 0.7 to 1.2, and particularly preferably 0.7 to 1.0 with respect to 1 mole of the phenol ring present in the structure of the novolak-type phenol resin (1). By setting the amount of amines used within the above range, an amine-modified phenol novolak resin can be obtained that forms a cured film having high solvent resistance when cured after film formation.

[0025] Also, the amount of formaldehyde used is preferably 0.8 to 1.2 moles, more preferably 0.9 to 1.1 moles of formaldehyde with respect to 1 mole of amines. Particularly from the viewpoint of reducing unreacted amines and formaldehyde, it is preferable that the amount of amines and formaldehyde are the same molar amount.

[0026] The ratio obtained by dividing the sum of the number of moles of amines and the number of moles of formaldehyde in the reaction by the number of moles of phenolic rings present in the structure of the novolak-type phenolic resin (1) ((number of moles of amines + number of moles of formaldehyde) / number of moles of phenolic rings present in the structure of the novolak-type phenolic resin (1)) is preferably in the range of 1.0 to 3.0 mol, more preferably 1.4 to 2.4, and particularly preferably 1.4 to 2.0. By setting the usage amounts of amines and formaldehyde within the above ranges, an amine-modified phenolic resin can be obtained that forms a cured film having high solvent resistance when cured after film formation.

[0027] The solvent used in the reaction may be any water-soluble solvent that can dissolve the novolak-type phenolic resin (1), and preferred examples include glycol ether solvents such as ethylene glycol monomethyl ether (methyl cellosolve), ethylene glycol monoethyl ether (ethyl cellosolve), ethylene glycol monobutyl ether (butyl cellosolve), propylene glycol monomethyl ether, and diethylene glycol monobutyl ether.

[0028] The novolak-type phenolic resin (1) used in the production of the amine-modified phenolic novolak resin of the present invention can be produced by a known method. Specifically, for example, phenol and formaldehyde are condensed or co-condensed under an acidic catalyst or without a catalyst, and then post-treatment such as washing with water and concentration under reduced pressure is performed to remove unreacted phenol and the catalyst, whereby it can be suitably produced.

[0029] The ratio of each component with n = 0 to 2 of the novolak-type phenolic resin (1) used in the production of the amine-modified phenolic resin of the present invention can be easily adjusted, for example, in the above method, by appropriately setting the reaction conditions such as the ratio of reaction raw materials, reaction time, and reaction temperature, and the post-treatment conditions such as washing with water and concentration under reduced pressure (removing water, unreacted raw materials, etc. under reduced pressure). In addition, those skilled in the art can accurately determine the actual reaction conditions by performing preliminary experiments as necessary.

[0030] The novolak-type phenol resin (1) used in the production of the amine-modified phenol resin of the present invention can be produced more precisely and simply, for example, by the "stepwise method" described on pages 47 to 49 of "Synthesis, Control, and Application Development of Phenol Resins and Derivatives" (Shigeki Inatomi, 2011, Information and Media Center). Specifically, methylol phenol is obtained by the phenolate method and reacted with phenol under an acid catalyst to easily obtain a novolak-type phenol resin having a specific molecular weight distribution.

[0031] When the novolak-type phenol resin (1) used in the production of the amine-modified phenol resin of the present invention is obtained by the stepwise method, the ratio of each component with n = 0 to 2 of the novolak-type phenol resin (1) is determined by the purity of the methylol form and the excess of phenols in the novolakization reaction. The purity of these methylol forms and the excess of phenols in the novolakization reaction can be easily achieved by adjusting the ratio of reaction raw materials, reaction time, and reaction temperature. In addition, those skilled in the art can accurately determine the actual reaction conditions by conducting preliminary experiments as necessary.

[0032] The weight average molecular weight (Mw) of the novolak-type phenol resin (1) used in the production of the amine-modified phenol resin of the present invention is not particularly limited, but is preferably 500 to 10,000, more preferably 500 to 5,000, still more preferably 500 to 2,000, and particularly preferably 1,000 to 1,500. The dispersity [weight average molecular weight / number average molecular weight] is preferably 1.0 to 1.2.

[0033] The amine-modified phenol novolak resin of the present invention is usually obtained in a solution state by the above reaction. The obtained amine-modified phenol novolak resin solution can be used as it is as a raw material for a metal surface treatment agent, and can also be concentrated or diluted as necessary before use.

[0034] The viscosity of the amine-modified phenol novolak resin of the present invention is preferably 200 mPa·s or more and 25,000 mP·s or less, more preferably 300 mPa·s or more and 1,500 mP·s or less, and still more preferably 400 mPa·s or more and 1,000 mP·s or less. By setting the viscosity within the above range, it can be easily used as a raw material for a metal surface treatment agent.

[0035] The aqueous phenol resin composition of the present invention contains any one of the above amine-modified phenol novolak resin and an acidic compound composed of an inorganic compound or an organic compound or both.

[0036] Examples of the inorganic compound include sulfuric acid, hydrochloric acid, phosphoric acid, hydrofluoric acid, and polyphosphoric acid, and examples of the organic compound include formic acid, acetic acid, propionic acid, citric acid, lactic acid, malic acid, fumaric acid, and maleic acid.

[0037] The aqueous phenol resin composition can be suitably used as a curing agent or an additive for a metal surface treatment agent, an aqueous paint, and an adhesive. From the viewpoints of corrosion resistance and adhesion when the aqueous phenol resin composition is used as a metal surface treatment agent, it is preferable that the aqueous phenol resin composition contains phosphoric acid as an acidic compound.

Examples

[0038] Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

[0039] [Analysis of novolak-type phenol resin] A method for analyzing a novolak-type phenol resin, which is a base resin of an amine-modified phenol novolak resin, will be described.

[0040] [Content of low molecular components (components with n = 0 to 2)] The molecular weight distribution of novolak-type phenolic resin was measured using a gel permeation chromatograph (GPC) analyzer, and the content of each of the dinuclear (n = 0) component, trinuclear (n = 1) component, and tetranuclear (n = 2) component was calculated as the area of each component relative to the area of the entire novolak-type phenolic resin. The area of each component was calculated with the straight part before and after the peak of the entire novolak-type phenolic resin as the baseline, and by vertically cutting at the lowest point between the peaks of each component to separate the peaks.

[0041] The equipment and measurement conditions used for the measurement are shown below. Equipment used: Waters Alliance 2695 Column: manufactured by SHODEX KF-804 × 1 piece KF-803 × 1 piece KF-802 × 1 piece KF-802.5 × 1 piece KF-801 × 1 piece Guard column: SHODEX KF-G Dissolution solution: tetrahydrofuran (THF) Detector: UV-Visivle Detector 2489 Detection wavelength: 254 nm Flow rate: 1 mL / min. Column oven temperature: 40 °C Injection volume: 100 μL Sample concentration: 0.1 mg / mL Analysis software: Empower3 (manufactured by Waters)

[0042] [Weight average molecular weight (Mw)] The molecular weight distribution of novolak-type phenolic resin was measured using the following equipment, and the weight average molecular weight (Mw) was determined by polystyrene conversion. Equipment used: Waters Alliance 2695 Column: manufactured by SHODEX KF-804 × 1 piece Guard column: SHODEX KF-G Dissolution solution: tetrahydrofuran (THF) Detector: UV-Visivle Detector 2489 Detection wavelength: 254 nm Flow rate: 1 mL / min. Column oven temperature: 40 °C Injection volume: 100 μL Sample concentration: 0.1 mg / mL Analysis software: Empower3 (manufactured by Waters)

[0043] [Hydroxyl equivalent] The hydroxyl equivalent was measured in accordance with JIS K0070. Specifically, the hydroxyl equivalent was measured by a back-titration method in which the phenolic resin was acetylated with an excess of acetic anhydride and the excess acetic anhydride was neutralized and titrated with an alkali.

[0044] The analysis results of the novolak-type phenolic resin used in the synthesis of the amine-modified phenolic resin are shown below. Phenolic resin 1: Novolak-type phenolic resin (1) The content rate of the dinuclear body (n = 0) was 5.6 area%, the content rate of the trinuclear body (n = 1) was 9.2 area%, the content rate of the tetranuclear body (n = 2) was 37.7 area%, the weight average molecular weight (Mw) was 1,000, and the hydroxyl equivalent was 107. Phenolic resin 2: Novolak-type phenolic resin (1) The content rate of the dinuclear body (n = 0) was 5.2 area%, the content rate of the trinuclear body (n = 1) was 7.6 area%, the content rate of the tetranuclear body (n = 2) was 23.1 area%, the weight average molecular weight (Mw) was 1,400, and the hydroxyl equivalent was 104. Phenolic resin 3: Novolak-type phenolic resin (1) The content rate of the dinuclear body (n = 0) was 9.0 area%, the content rate of the trinuclear body (n = 1) was 7.2 area%, the content rate of the tetranuclear body (n = 2) was 5.9 area%, the weight average molecular weight (Mw) was 3,500, and the hydroxyl equivalent was 107. Phenolic resin 4: A phenolic resin other than novolak-type phenolic resin (1) (phenol-formaldehyde condensate) The content ratio of binuclear bodies (n = 0) was 18.2 area%, the content ratio of trinuclear bodies (n = 1) was 13.6 area%, the content ratio of tetranuclear bodies (n = 2) was 10.9 area%, the weight average molecular weight (Mw) was 1,300, and the hydroxyl equivalent was 107. Phenolic resin 5: Phenolic resin other than novolak type phenolic resin (1) (phenol-formaldehyde condensate) The content ratio of binuclear bodies (n = 0) was 13.2 area%, the content ratio of trinuclear bodies (n = 1) was 10.0 area%, the content ratio of tetranuclear bodies (n = 2) was 8.2 area%, the weight average molecular weight (Mw) was 1,900, and the hydroxyl equivalent was 107.

[0045] [2] Analysis and evaluation of amine-modified phenol novolak resin The analysis method and evaluation method of amine-modified phenol novolak resin will be described.

[0046] [Viscosity] It was measured with an E-type viscometer in accordance with JIS K7117-2:1999.

[0047] [Non-volatile content] 1.0 g of amine-modified phenol novolak resin was weighed into an aluminum cup with a diameter of φ50 mm, and it was determined from the remaining amount after drying in an oven at 180 °C for 1 hour.

[0048] [Acid solubility and dissolution time] 0.2 g (in terms of solid content) of amine-modified phenol resin solution was weighed into a 200 mL beaker, 100 mL of phosphoric acid aqueous solution adjusted to pH 2.0 was added, and then it was immediately stirred with a magnetic stirrer to observe whether it dissolved or not, and the dissolution time was measured. The time from the start of stirring with the magnetic stirrer until the amine-modified phenol resin dissolved in the phosphoric acid aqueous solution was defined as the dissolution time. In addition, when it became a visually transparent and uniform solution, it was judged that it had dissolved.

[0049] [Example 1] Into a reactor equipped with a stirrer, a condenser and a thermometer, 100 g of a novolac-type phenol resin (Phenol Resin 1: hydroxyl equivalent 107 g / eq., Mw 1,000), 168 g of butyl cellosolve and 95.3 g (0.91 mol) of diethanolamine were added and dissolved at 80°C. Then, 64.8 g (0.91 mol) of 42% formalin was added over 1 hour. After the addition, the temperature was raised to 100°C and the reaction was carried out at the same temperature for 6 hours to obtain a solution containing amine-modified phenol resin A. The obtained solution containing amine-modified phenol resin A had a viscosity of 490 mPa·s and a non-volatile content of 46%. The evaluation results are shown in Table 1.

[0050] [Example 2] Into a reactor equipped with a stirrer, a condenser and a thermometer, 100 g of a novolac-type phenol resin (Phenol Resin 1: hydroxyl equivalent 107 g / eq., Mw 1,000), 168 g of butyl cellosolve and 68.8 g (0.65 mol) of diethanolamine were added and dissolved at 80°C. Then, 46.8 g (0.65 mol) of 42% formalin was added over 1 hour. After the addition, the temperature was raised to 100°C and the reaction was carried out at the same temperature for 6 hours to obtain a solution containing amine-modified phenol resin B. The obtained solution containing amine-modified phenol resin B had a viscosity of 470 mPa·s and a non-volatile content of 47%. The evaluation results are shown in Table 1.

[0051] [Example 3] Into a reactor equipped with a stirrer, a condenser and a thermometer, 100 g of a novolac-type phenol resin (Phenol Resin 2: hydroxyl equivalent 104 g / eq., Mw 1,400), 168 g of butyl cellosolve and 98.1 g (0.93 mol) of diethanolamine were added and dissolved at 80°C. Then, 66.7 g (0.93 mol) of 42% formalin was added over 1 hour. After the addition, the temperature was raised to 100°C and the reaction was carried out at the same temperature for 6 hours to obtain a solution containing amine-modified phenol resin C. The obtained solution containing amine-modified phenol resin C had a viscosity of 960 mPa·s and a non-volatile content of 48%. The evaluation results are shown in Table 1.

[0052] [Example 4] Into a reactor equipped with a stirrer, a condenser and a thermometer, 100 g of a novolak-type phenol resin (Phenol Resin 3: hydroxyl equivalent 107 g / eq., Mw 3,500), 168 g of butyl cellosolve and 95.3 g (0.91 mol) of diethanolamine were added and dissolved at 80°C. Subsequently, 64.8 g (0.91 mol) of 42% formalin was added over 1 hour. After the addition, the temperature was raised to 100°C and the reaction was carried out at the same temperature for 3 hours to obtain a solution containing amine-modified phenol resin D. The obtained solution containing amine-modified phenol resin D had a viscosity of 2,400 mPa·s and a non-volatile content of 48%. The evaluation results are shown in Table 1.

[0053] [Comparative Example 1] Into a reactor equipped with a stirrer, a condenser and a thermometer, 100 g of a novolak-type phenol resin (Phenol Resin 4: hydroxyl equivalent 107 g / eq., Mw 1,300), 168 g of butyl cellosolve and 95.3 g (0.91 mol) of diethanolamine were added and dissolved at 80°C. Subsequently, 64.8 g (0.91 mol) of 42% formalin was added over 1 hour. After the addition, the temperature was raised to 100°C and the reaction was carried out at the same temperature for 6 hours to obtain a solution containing amine-modified phenol resin E. The obtained solution containing amine-modified phenol resin E had a viscosity of 630 mPa·s and a non-volatile content of 49%. The evaluation results are shown in Table 1.

[0054] [Comparative Example 2] Into a reactor equipped with a stirrer, a condenser and a thermometer, 100 g of a novolak-type phenol resin (Phenol Resin 5: hydroxyl equivalent 107 g / eq., Mw 1,900), 168 g of butyl cellosolve and 95.3 g (0.91 mol) of diethanolamine were added and dissolved at 80°C. Subsequently, 64.8 g (0.91 mol) of 42% formalin was added over 1 hour. After the addition, the temperature was raised to 100°C and the reaction was carried out at the same temperature for 6 hours to obtain a solution containing amine-modified phenol resin F. The obtained solution containing amine-modified phenol resin F had a viscosity of 890 mPa·s and a non-volatile content of 48%. The evaluation results are shown in Table 1.

[0055] [Comparative Example 3] To a reactor equipped with a stirrer, a condenser and a thermometer, 100 g of novolac-type phenol resin (phenol resin 4: hydroxyl equivalent 107 g / eq., Mw 1,300), 168 g of butyl cellosolve and 68.8 g (0.65 mol) of diethanolamine were added and dissolved at 80°C. Then, 46.8 g (0.65 mol) of 42% formalin was added over 1 hour. After the addition, the temperature was raised to 100°C and the reaction was carried out at the same temperature for 6 hours to obtain a solution containing amine-modified phenol resin G. The obtained solution containing amine-modified phenol resin G had a viscosity of 560 mPa·s and a non-volatile content of 47%. The evaluation results are shown in Table 1.

[0056] [3] Preparation and evaluation of cured product (coating film) of amine-modified phenol novolac resin The preparation and evaluation method of the cured product (coating film) of the amine-modified phenol novolac resin will be described.

[0057] [Solvent resistance (weight loss rate of cured coating film)] The amine-modified phenol novolac resin solution obtained in the examples and comparative examples was applied to a degreased commercially available aluminum plate (JIS A5052, 75 mm × 100 mm) with an applicator (gap: 50 μm), and baked at 190°C for 10 minutes to prepare a test sample with a coating film formed on the aluminum plate. The test sample was placed upright in a 1L cylindrical flask equipped with a condenser, and a solvent immersion test was carried out by adding dimethyl carbonate until the test sample was completely immersed and heating at 85°C for 24 hours. The weight loss of the coating film before and after the solvent immersion test was calculated and used as an index of solvent resistance. The obtained results are shown in Table 1 with Comparative Example 1 as 100 and presented in index form.

[0058]

Table 1

[0059] As shown in Table 1, it can be seen that the amine-modified phenol novolac resin of the present invention has excellent solubility in acidic aqueous solutions and a cured product with excellent solvent resistance can be obtained.

Claims

1. An amine-modified phenol novolak resin which is a reaction product of a novolak-type phenol resin represented by the following general formula (1), formaldehyde, and amines. 【Chemical 1】 In the above general formula (1), n is 0 or a positive integer, and the total area of the components where n = 0 and the components where n = 1 is 10 area% or more and 20 area% or less with respect to the total area of the novolak-type phenol resin in gel permeation chromatograph analysis. The area of each component is the area calculated by using the straight part before and after the peak of the entire novolak-type phenol resin as the baseline, and vertically cutting at the lowest point between the peaks of each component to separate the peaks.

2. The amine-modified phenol novolak resin according to Claim 1, wherein the area of the component where n = 2 is 15 area% or more and 45 area% or less with respect to the total area of the novolak-type phenol resin in gel permeation chromatograph analysis.

3. The amine-modified phenol novolak resin according to Claim 1 or Claim 2, wherein the molar number of formaldehyde with respect to 1 mol of the phenol ring contained in the structure of the novolak-type phenol resin is 0.5 or more, the molar number of amines is 0.5 or more, and the sum of the molar number of formaldehyde and the molar number of amines is 1.0 to 2.4 mol.

4. An aqueous phenol resin composition containing the amine-modified phenol novolak resin according to any one of Claims 1 to 3 and any one kind of an acidic compound composed of an inorganic compound, an organic compound, or both of them.

5. A metal surface treatment agent containing the aqueous phenol resin composition according to Claim 4.

6. An aqueous paint containing the aqueous phenol resin composition according to Claim 4.

7. A method for producing an amine-modified phenol novolak resin by reacting a novolak-type phenol resin represented by the following general formula (1), formaldehyde, and amines. [Chemical Formula 2] In the above general formula (1), n is 0 or a positive integer, and the total area of the components where n = 0 and the components where n = 1 is 10 area% or more and 20 area% or less with respect to the total area of the novolak-type phenol resin in gel permeation chromatograph analysis. The area of each component is the area calculated by using the straight part before and after the peak of the entire novolak-type phenol resin as the baseline, and vertically cutting at the lowest point between the peaks of each component to separate the peaks.

8. The manufacturing method of the amine-modified phenol novolak resin according to claim 7, wherein the area of the component with n = 2 is 15 area % or more and 45 area % or less with respect to the total area of the novolak-type phenol resin in gel permeation chromatograph analysis.

9. The molar number of formaldehyde with respect to 1 mol of the phenol ring contained in the structure of the novolak-type phenol resin is 0.5 or more, the molar number of amines is 0.5 or more, and the sum of the molar number of formaldehyde and the molar number of amines is 1.0 to 2.4 mol. The manufacturing method of the amine-modified phenol novolak resin according to claim 7 or claim 8. ​

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