Delayed semi-non-flammable phenolic foam and its manufacturing method

Abstract

The present invention relates to a retardant semi-flame retardant phenolic foam and a method for manufacturing the same. More specifically, it relates to a retardant semi-flame retardant phenolic foam and a method for manufacturing the same, in which the mixing efficiency is increased by controlling the reactivity of the mixed slurry when mixing the resin and the curing agent and controlling the rate of increase of the reaction temperature when manufacturing the phenolic resin, thereby improving thermal insulation, semi-flame retardant performance, and mechanical stability.

Description

Technology Field

[0001] The present invention relates to a retardant semi-flame retardant phenolic foam and a method for manufacturing the same. More specifically, it relates to a retardant semi-flame retardant phenolic foam and a method for manufacturing the same, in which the mixing efficiency is increased by controlling the reactivity of the mixed slurry when mixing the resin and the curing agent and controlling the rate of increase of the reaction temperature when manufacturing the phenolic resin, thereby improving thermal insulation, semi-flame retardant performance, and mechanical stability. Background Technology

[0003] Phenolic foam, a semi-noncombustible material exhibiting excellent thermal insulation and flame retardancy, is attracting attention as a building material for preventing fire hazards and minimizing the spread of large-scale fires.

[0004] The above phenolic foam has the most thermally and chemically stable properties among foamed plastics, and at the same time exhibits excellent thermal insulation and flame retardancy, thus offering excellent fire safety. However, it contains formaldehyde, a Group 1 carcinogen, which poses a problem as it can have harmful effects on the human body.

[0005] Due to the above-mentioned problems, there is a need to develop a semi-flame-retardant phenolic foam that exhibits excellent mechanical stability even with a reduced formaldehyde content, while simultaneously exhibiting excellent thermal insulation and flame resistance, and a method for manufacturing the same. The problem to be solved

[0007] The objective of the present invention is to provide a retardant semi-flame phenolic foam with stabilized thermal insulation performance and semi-flame retardant performance, and a method for manufacturing the same.

[0008] In addition, the objective of the present invention is to provide a retardant semi-flame-retardant phenolic foam with reduced formaldehyde emissions and a method for manufacturing the same.

[0009] In addition, the objective of the present invention is to provide a retardant semi-flame-retardant phenolic foam with improved mechanical stability without a separate curing process, and a method for manufacturing the same.

[0010] The technical problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned technical problems will be clearly understood by those skilled in the art from the description of the present invention. means of solving the problem

[0012] To achieve the above objective, the present invention provides a retardant semi-flame-retardant phenolic foam and a method for manufacturing the same.

[0013] The present invention provides a phenol foam comprising a phenol-melamine resin, a flame retardant, an additive, a curing agent, and a foaming agent, wherein the phenol-melamine resin comprises a resol phenol resin, and the curing agent comprises 10 to 20 weight percent of water relative to 100 weight percent of the curing agent.

[0014] In the present invention, the phenol-melamine resin is characterized by comprising 10 to 30 parts by weight of melamine and 0.05 to 0.1 parts by weight of formaldehyde per 100 parts by weight of the phenol-melamine resin.

[0015] In the present invention, the phenol-melamine resin is characterized by having a molecular weight distribution (PDI) of 1 to 1.5 and a viscosity of 5,000 to 8,000 cps.

[0016] In the present invention, the curing agent is phenolsulfonic acid and is characterized by being included in an amount of 10 to 20 weight% relative to 100 weight% of the phenol foam.

[0017] The present invention provides a method for manufacturing a retardant semi-flame-retardant phenolic foam, comprising the steps of: manufacturing a phenol-melamine resin; mixing a flame retardant and a diluent to manufacture a flame retardant mixture; introducing and mixing the flame retardant mixture and an additive into the phenol-melamine resin; stirring the phenol-melamine resin mixed with the flame retardant, a curing agent, and a foaming agent; obtaining a slurry manufactured by stirring; and evaporating the moisture from the slurry. Effects of the invention

[0019] By means of the solution to the above problem, the present invention can provide a retardant semi-flame-retardant phenolic foam with stabilized thermal insulation performance and semi-flame-retardant performance, and a method for manufacturing the same.

[0020] In addition, the present invention can provide a retardant semi-flame-retardant phenolic foam with reduced formaldehyde emissions and a method for manufacturing the same.

[0021] In addition, the present invention can provide a retardant semi-flame-retardant phenolic foam with improved mechanical stability without a separate aging process, and a method for manufacturing the same.

[0022] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description in the claims. Brief explanation of the drawing

[0024] Figure 1 is a diagram showing the process of a flame retardant sedimentation test of a phenol-melamine resin according to the present invention. Figure 2 is a diagram showing the reaction temperature according to the reaction time of a phenol foam containing a curing agent according to the present invention. Specific details for implementing the invention

[0025] The terms used in this specification have been selected based on currently widely used general terms whenever possible, taking into account their functions in the present invention; however, these terms may vary depending on the intent of those skilled in the art, case law, the emergence of new technologies, etc. Additionally, in specific cases, terms have been arbitrarily selected by the applicant, and in such cases, their meanings will be described in detail in the corresponding description of the invention. Therefore, the terms used in this invention should be defined not merely by their names, but based on their meanings and the overall content of the invention.

[0026] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application.

[0027] Numerical ranges include the values ​​defined in the above ranges. All maximum numerical limits given throughout this specification include all lower numerical limits as clearly written. All minimum numerical limits given throughout this specification include all higher numerical limits as clearly written. All numerical limits given throughout this specification will include all better numerical ranges within a wider numerical range, as clearly written.

[0029] Retardant semi-fireproof phenolic foam

[0030] The present invention relates to a retardant semi-flame-retardant phenolic foam.

[0031] The present invention relates to a phenol foam comprising a phenol-melamine resin, a flame retardant, an additive, a curing agent, and a foaming agent, wherein the phenol-melamine resin comprises a resol phenol resin, and the curing agent comprises 10 to 20 weight percent of water relative to 100 weight percent of the curing agent.

[0032] In the phenol-melamine resin containing the above melamine, the melamine undergoes modification during the manufacture of the phenol-melamine resin, thereby exhibiting an oxygen blocking effect through nitrogen within the melamine, which may enable increased flame retardancy and a reduction in the formaldehyde content by reacting unreacted formaldehyde with the melamine.

[0033] The above curing agent is diluted with water, and the phenol foam containing the curing agent diluted as above may have a slower reaction temperature of the slurry before foaming, which may increase the mixing efficiency during foaming.

[0034] When water is included in an amount of less than 10% by weight relative to 100% by weight of the curing agent, rapid reactivity is observed during the manufacture of the phenol foam, and when it is included in an amount exceeding 20% ​​by weight, the formation of the slurry proceeds slowly during the manufacture of the foam, resulting in post-foaming in the final composition, which may lead to a decrease in physical properties.

[0035] The above resol phenol resin may have a low formaldehyde content, and the curing agent may be a diluted one containing water, which causes the reaction temperature of the phenol resin containing it to rise slowly.

[0036] When mixing the above resol resin and the above curing agent, the mixing time may be increased by controlling the reactivity of the mixed slurry to increase the dispersion efficiency of the flame retardant, and thereby excellent flame retardancy may be exhibited.

[0037] The above phenol-melamine resin may have a reaction temperature that increases at an average heating rate of 2.0 to 2.5 ℃ / min. By increasing the mixing time during slurry preparation through tidal production exhibiting such a slow heating rate, the dispersion efficiency of the flame retardant may be increased, and thereby excellent flame retardancy may be exhibited.

[0038] The above-mentioned flame-retardant semi-flame-retardant phenol foam may comprise 50 to 64 weight% of the phenol-melamine resin, 8 to 10 weight% of the flame retardant, 8 to 12 weight% of the additive, 15 to 20 weight% of the curing agent, and 5 to 8 weight% of the foaming agent relative to 100 weight% of the above-mentioned flame-retardant semi-flame-retardant phenol foam, but is not limited thereto.

[0039] The flame retardant may be one or more selected from the group consisting of red, ammonium polyphosphate, and condensed phosphate ester, or a mixture of two or more selected from the group. Preferably, the red, ammonium polyphosphate, and condensed phosphate ester may be mixed in a weight ratio of (5 to 6) : (1 to 2) : (2 to 3).

[0040] The above additives may include a foam stabilizer, an FF capture agent, an inorganic filler, and a diluent. Preferably, the foam stabilizer may be siloxane-based, the FF capture agent may be urea, the inorganic filler may be calcium carbonate, and the diluent may be a mixture of ethylene glycol and castor oil, but is not limited thereto.

[0041] In the present invention, the phenol-melamine resin may comprise 10 to 30 parts by weight of melamine and 0.05 to 0.1 parts by weight of formaldehyde per 100 parts by weight of the phenol-melamine resin.

[0042] If the above phenol-melamine resin contains less than 10 parts by weight of melamine relative to 100 parts by weight of the above phenol-melamine resin, there may be a problem in that the content of formaldehyde, a toxic substance, must be increased.

[0043] In the present invention, the phenol-melamine resin may have a molecular weight distribution (PDI) of 1 to 1.5 and a viscosity of 5,000 to 8,000 cps. By including a phenol-melamine resin having such a viscosity, the dispersion efficiency of the inorganic material can be improved, and the precipitation of the flame retardant can be prevented, thereby maintaining excellent flame retardancy.

[0044] If the viscosity is less than 5,000 cps, the mixed powder flame retardant and the additive may settle quickly and not be dispersed in the slurry being manufactured, and if it exceeds 8,000 cps, the dispersibility of the flame retardant and the additive may decrease, resulting in poor mixing ability.

[0045] In the present invention, the curing agent is phenolsulfonic acid and may be included in an amount of 10 to 20 weight% relative to 100 weight% of the phenol foam. If the curing agent is included in an amount of less than 10 weight% relative to 100 weight% of the phenol foam, the reaction rate of the slurry being produced may not be sufficiently reduced, and if it is included in an amount exceeding 20 weight%, excessive curing may occur, and defects such as cracks may occur in the foam being produced.

[0047] Method for manufacturing retardant semi-flame-retardant phenolic foam

[0048] The present invention relates to a method for manufacturing a retardant semi-flame-retardant phenolic foam.

[0049] The present invention relates to a method for manufacturing a retardant semi-flame-retardant phenolic foam, comprising the steps of: manufacturing a phenol-melamine resin; mixing a flame retardant and a diluent to manufacture a flame retardant mixture; introducing and mixing the flame retardant mixture and an additive into the phenol-melamine resin; stirring the phenol-melamine resin mixed with the flame retardant, a curing agent, and a foaming agent; obtaining a slurry manufactured by stirring; and evaporating the moisture from the slurry.

[0050] The step of manufacturing the above phenol-melamine resin may comprise: mixing phenol and formaldehyde in a molar ratio of 1: (1.5 to 2); adding melamine to the phenol mixture; adding sodium hydroxide, which is a reaction catalyst, to the phenol-melamine mixture; gradually increasing the reaction temperature of the phenol-melamine mixture containing the reaction catalyst until it reaches 50 to 80°C to carry out addition polymerization to produce a methyl phenol precursor and a methyl melamine precursor; and carrying out condensation polymerization of the precursors to produce the phenol-melamine resin.

[0051] The step of stirring the curing agent and the foaming agent may be performed at a speed of 3,500 to 4,000 RPM. If the stirring speed is less than 3,500 RPM, the foaming performance may be reduced, and if it exceeds 4,000 RPM, cracks may occur due to excessive foaming.

[0052] The retardant semi-flame-retardant phenolic foam produced according to the above manufacturing method is a phenolic foam comprising a phenol-melamine resin, a flame retardant, an additive, a curing agent, and a foaming agent, wherein the phenol-melamine resin comprises a resol phenolic resin, and the curing agent may comprise 10 to 20 weight percent of water relative to 100 weight percent of the curing agent.

[0053] In the phenol-melamine resin containing the above melamine, the melamine undergoes modification during the manufacture of the phenol-melamine resin, thereby exhibiting an oxygen blocking effect through nitrogen within the melamine, which may enable increased flame retardancy and a reduction in the formaldehyde content by reacting unreacted formaldehyde with the melamine.

[0054] The above curing agent is diluted with water, and the phenol foam containing the curing agent diluted as above may have a slower reaction temperature of the slurry before foaming, which may increase the mixing efficiency during foaming.

[0055] When water is included in an amount of less than 10% by weight relative to 100% by weight of the curing agent, rapid reactivity is observed during the manufacture of the phenol foam, and when it is included in an amount exceeding 20% ​​by weight, the formation of the slurry proceeds slowly during the manufacture of the foam, resulting in post-foaming in the final composition, which may lead to a decrease in physical properties.

[0056] The above resol phenol resin may have a low formaldehyde content, and the curing agent may be a diluted one containing water, which causes the reaction temperature of the phenol resin containing it to rise slowly.

[0057] When mixing the above resol resin and the above curing agent, the mixing time may be increased by controlling the reactivity of the mixed slurry to increase the dispersion efficiency of the flame retardant, and thereby excellent flame retardancy may be exhibited.

[0058] The above phenol-melamine resin may have a reaction temperature that increases at an average heating rate of 2.0 to 2.5 ℃ / min. By increasing the mixing time during slurry preparation through tidal production exhibiting such a slow heating rate, the dispersion efficiency of the flame retardant may be increased, and thereby excellent flame retardancy may be exhibited.

[0059] The above-mentioned flame-retardant semi-flame-retardant phenol foam may comprise 50 to 64 weight% of the phenol-melamine resin, 8 to 10 weight% of the flame retardant, 8 to 12 weight% of the additive, 15 to 20 weight% of the curing agent, and 5 to 8 weight% of the foaming agent relative to 100 weight% of the above-mentioned flame-retardant semi-flame-retardant phenol foam, but is not limited thereto.

[0060] The flame retardant may be one or more selected from the group consisting of red, ammonium polyphosphate, and condensed phosphate ester, or a mixture of two or more selected from the group. Preferably, the red, ammonium polyphosphate, and condensed phosphate ester may be mixed in a weight ratio of (5 to 6) : (1 to 2) : (2 to 3).

[0061] The above additives may include a foam stabilizer, an FF capture agent, an inorganic filler, and a diluent. Preferably, the foam stabilizer may be siloxane-based, the FF capture agent may be urea, the inorganic filler may be calcium carbonate, and the diluent may be a mixture of ethylene glycol and castor oil, but is not limited thereto.

[0062] In the present invention, the phenol-melamine resin may comprise 10 to 30 parts by weight of melamine and 0.05 to 0.1 parts by weight of formaldehyde per 100 parts by weight of the phenol-melamine resin.

[0063] If the above phenol-melamine resin contains less than 10 parts by weight of melamine relative to 100 parts by weight of the above phenol-melamine resin, there may be a problem in that the content of formaldehyde, a toxic substance, must be increased.

[0064] In the present invention, the phenol-melamine resin may have a molecular weight distribution (PDI) of 1 to 1.5 and a viscosity of 5,000 to 8,000 cps. By including a phenol-melamine resin having such a viscosity, the dispersion efficiency of the inorganic material can be improved, and the precipitation of the flame retardant can be prevented, thereby maintaining excellent flame retardancy.

[0065] If the viscosity is less than 5,000 cps, the mixed powder flame retardant and the additive may settle quickly and not be dispersed in the slurry being manufactured, and if it exceeds 8,000 cps, the dispersibility of the flame retardant and the additive may decrease, resulting in poor mixing ability.

[0066] In the present invention, the curing agent is phenolsulfonic acid and may be included in an amount of 10 to 20 weight% relative to 100 weight% of the phenol foam. If the curing agent is included in an amount of less than 10 weight% relative to 100 weight% of the phenol foam, the reaction rate of the slurry being produced may not be sufficiently reduced, and if it is included in an amount exceeding 20 weight%, excessive curing may occur, and defects such as cracks may occur in the foam being produced.

[0068] Examples

[0069] The embodiments of the present invention are described in detail below, but it is obvious that the present invention is not limited by the following embodiments.

[0070] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described in detail below. However, the present invention is not limited to the embodiments disclosed below but can be implemented in various different forms. The embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims.

[0072] <Example 1> Phenol-melamine resin containing a flame retardant

[0073] Phenol and formaldehyde were mixed in a molar ratio of 1:(1.5 to 2), and then melamine was added to the phenol mixture. Sodium hydroxide, acting as a reaction catalyst, was added to the phenol-melamine mixture prepared in this manner, and the reaction temperature was gradually increased until it reached 80°C to carry out addition polymerization, thereby producing a methyl phenol precursor and a methyl melamine precursor. Subsequently, a phenol-melamine resin was prepared by carrying out condensation polymerization of the precursors. Afterward, a flame retardant was added to the phenol-melamine resin and mixed. The phenol-melamine resin prepared as described above exhibited a viscosity of 5,500 cps.

[0075] <Comparative Example 1> Phenol-melamine resin containing flame retardants with different viscosities

[0076] A phenol-melamine resin was prepared in the same manner as in Example 1 above, except that the phenol-melamine resin was controlled differently. The viscosity of the prepared phenol-melamine resin is as shown in [Table 1] below.

[0077]

[0079] <Example 2> Semi-noncombustible phenolic foam containing phenolsulfonic acid (PSA) curing agent

[0080] A phenol-melamine resin was prepared using the same method as in Example 1 above. A flame retardant mixture was prepared by mixing a flame retardant and a diluent, and then the flame retardant mixture and additives were added to and mixed with the phenol-melamine resin. A curing agent and a foaming agent were added to the phenol-melamine resin mixed with the flame retardant, and then stirred to prepare a slurry. After evaporating the moisture from the slurry, the material was cut and processed to produce a semi-flame-retardant phenol foam. At this time, the curing agent is phenolsulfonic acid (PSA), and it is diluted to contain 10% moisture relative to 100% by weight of the phenolsulfonic acid.

[0082] <Comparative Example 2> Semi-noncombustible phenolic foam containing PTSA curing agent

[0083] A phenol-melamine resin was prepared in the same manner as in Example 2 above, except that p-toluenesulfonic acid (PTSA) was used as a curing agent.

[0085] <Example 3> Semi-noncombustible phenolic foam containing phenol-melamine resin

[0086] A semi-flame-retardant phenolic foam was prepared using the same method as in Example 2 above. The composition of the semi-flame-retardant phenolic foam is as shown in [Table 2] below. The composition represents weight% relative to 100 weight% of the resin.

[0087]

[0088] <Comparative Example 3> Phenolic foam containing phenol resol resin

[0089] A semi-flame-retardant phenolic foam was prepared in the same manner as in Example 2 above, except that it did not contain phenol-melamine resin and contained phenol resol resin. The composition of the semi-flame-retardant phenolic foam is as shown in [Table 3] below. The composition represents weight% relative to 100 weight% of the resin.

[0090]

[0091] <Experimental Example 1> Experiment on Flame Retardant Sedimentation According to Phenol-Melamine Resin Viscosity

[0092] The sedimentation experiment of the phenol-melamine resin prepared in Example 1 and Comparative Example 1 was conducted as shown in Fig. 1. More specifically, 50 g of the phenol-melamine resin containing the flame retardant prepared in Example 1 and Comparative Example 1 and 200 g of methyl alcohol were placed in a beaker and stirred for 5 minutes. The mixture stirred and mixed was filtered through filter paper to obtain the phenol-melamine resin from which the mixed flame retardant powder had been separated. Subsequently, the phenol-melamine resin from which the flame retardant had been separated was placed in an oven set at 110°C to volatilize the methanol solution contained therein, and the weight was measured to calculate the total amount of internal flame retardant remaining in the phenol-melamine resin. This process was repeated over time after mixing, and the calculation results are shown in [Table 4] below.

[0093]

[0094] [Table 1] above shows the weight percentage of the flame retardant included relative to 100 weight% of the phenol-melamine resin. As shown in [Table 1], the phenol-melamine resin of Example 1 maintains the flame retardant ratio with almost no sedimentation of the flame retardant immediately after mixing and even after 2 hours, whereas the phenol-melamine resins of Comparative Examples 1-1 and 1-2 show that when the viscosity is low, the flame retardant settles within a short period of time, resulting in a lower flame retardant ratio.

[0095] Through the above results, it was confirmed that the flame-retardant semi-flame-retardant phenolic foam according to the present invention can maintain excellent flame retardancy by improving the dispersion efficiency of inorganic materials and preventing the precipitation of flame retardants through a viscosity of 5,000 to 8,000 cps.

[0097] <Experimental Example 2> Measurement of reaction temperature according to reaction time

[0098] The reaction intensity of the phenol foam prepared in Example 2 and Comparative Example 2 according to reaction time was measured, and the results are shown in Figure 2.

[0099] As shown in Figure 2, in the case of the phenol foam containing the PTSA curing agent of Comparative Example 2, the reaction temperature reached about 115 ℃ within 20 minutes after the start of the reaction, showing a very rapid rise in reaction temperature. On the other hand, in the case of the phenol foam containing the diluted PSA curing agent of Example 1, the reaction temperature reached about 115 ℃ after 40 minutes after the start of the reaction, and it was found that the reaction temperature rose very slowly compared to the phenol foam of Comparative Example 2.

[0100] Through the above results, it was confirmed that the delayed semi-flammable phenol foam according to the present invention contains a diluted curing agent, which causes the reaction temperature to rise slowly, thereby improving mixing efficiency during foaming.

[0102] <Experimental Example 3> Analysis of Physical Properties of Phenol Foam

[0103] The resin viscosity, formaldehyde content, closed cell ratio, heat release, carbonization depth, maximum crack length, formaldehyde release amount, and initial thermal conductivity of the phenolic foam prepared in Example 3 and Comparative Example 3 were measured, and the results are shown in [Table 5] below.

[0104]

[0105] As shown in [Table 5] above, compared to the semi-flame-retardant phenolic foam of Comparative Examples 3-1 to 3-3 containing the resol phenolic resin, the semi-flame-retardant phenolic foam of Examples 3-1 to 3-3 containing the phenol-melamine resin showed a low formaldehyde content and a low formaldehyde emission amount due to the inclusion of melamine. In addition, it showed a high closed-cell ratio, resulting in a low average carbonization depth and crack length, and was found to be mechanically stable. Furthermore, it exhibited excellent flame-retardant and non-flame resistance by showing a low total heat release and initial thermal conductivity.

[0106] Through the above results, it was confirmed that the retardant semi-flame phenolic foam according to the present invention can exhibit a low formaldehyde content through melamine modification and a low formaldehyde emission amount, while simultaneously exhibiting excellent mechanical stability and excellent semi-flame retardancy and flame retardancy.

Claims

Claim 1 A phenol foam comprising a phenol-melamine resin, a flame retardant, an additive, a curing agent, and a foaming agent, wherein the phenol-melamine resin comprises a resol phenol resin, and comprises 10 to 30 parts by weight of melamine and 0.05 to 0.1 parts by weight of formaldehyde per 100 parts by weight of the phenol-melamine resin, has a molecular weight distribution (PDI) of 1 to 1.5 and a viscosity of 5,000 to 8,000 cps, and the curing agent comprises 10 to 20% by weight of water per 100% by weight of the curing agent, a retardant semi-flame-retardant phenol foam. Claim 2 delete Claim 3 delete Claim 4 A retardant semi-flame-retardant phenolic foam according to claim 1, characterized in that the curing agent is phenolsulfonic acid and is included in an amount of 10 to 20 weight% relative to 100 weight% of the phenolic foam. Claim 5 A step of manufacturing a phenol-melamine resin; a step of preparing a flame retardant mixture by mixing a flame retardant and a diluent; a step of adding and mixing the flame retardant mixture and additives to the phenol-melamine resin; a step of stirring the phenol-melamine resin mixed with the flame retardant, a curing agent containing 10 to 20 weight% of moisture relative to 100 weight% of the curing agent, and a foaming agent; and a step of obtaining a slurry prepared by stirring and having a reduced reaction rate. A method for manufacturing a retardant semi-flammable phenolic foam, comprising: a step of evaporating moisture from the slurry; wherein the step of manufacturing the phenol-melamine resin comprises: a step of mixing phenol and formaldehyde in a molar ratio of 1: (1.5 to 2); a step of introducing melamine into the phenol mixture to produce a phenol-melamine mixture; a step of adding sodium hydroxide, which is a reaction catalyst, to the phenol-melamine mixture; a step of increasing the reaction temperature of the phenol-melamine mixture containing the reaction catalyst until it reaches 50 to 80 ℃ to carry out addition polymerization to produce a methyl phenol precursor and a methyl melamine precursor; and a step of carrying out condensation polymerization of the precursors to produce a phenol-melamine resin.

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