WO2017146421A1 - Method for producing water-based resin without formaldehyde emission - Google Patents

Abstract

The present invention relates to a method for producing a water-based resin, the method eliminating by a chemical means formaldehyde gas generated during production of water-based thermoset resin such as water-based urea resin, water-based melamine resin, water-based phenol resin and water-based modified urea resin. Formaldehyde gas generated during the production of water-based resin can be removed by means of an effective and economical process when the method according to the present invention is used. Formaldehyde gas is not emitted when said water-based resin is used for adhering hardwood floor, furniture, wallpaper, and the like. As such, environment-friendly building material can be used, and thus the sick house syndrome can be expected to be preemptively prevented or inhibited when the water-based resin to which the process of the present invention has been applied is used.

Description

Process for producing water-based resin excluding formaldehyde emission

The present invention relates to a method for producing a water-based resin, and more particularly to a method for producing an environmentally friendly water-based resin to exclude the release of formaldehyde gas harmful to the human body.

As society develops economically, well-being, which refers to the type of life or culture that pursues a happy and beautiful life by harmonizing physical and mental health, not simply economic and material abundance, is an important factor that determines quality of life. Is considered. Therefore, modern people pursue a clean and pollution-free lifestyle with harmony with their surroundings.

Factors that inhibit well-being include environmental pollution, such as pollution of the surrounding environment, especially air pollution from living environments. In particular, “sick house syndrome” is a term used to refer to the health problems and discomforts of residents in new buildings. New homes contain volatile organic compounds (VOCs) and various contaminants, such as building materials used to build new homes and buildings, hazardous materials from insulation materials and wallpaper, radon from homes, It is a term that encompasses the health problems and discomfort that residents feel due to pollutants such as asbestos, carbon monoxide, carbon dioxide, nitrogen oxides, ozone, and fine dust.

Representative materials that cause sick house syndrome are interior materials, and chemical adhesives that attach wood flooring, furniture, and silk wallpaper are known as the main culprit of sick house syndrome. As a chemical adhesive for attaching these interior materials, a waterborne resin containing formaldehyde, for example, an aqueous urea / melamine / phenol resin, is mainly used. A formalin aqueous solution is used as a raw material of these aqueous resins, and thus a small amount of formaldehyde that pollutes the atmospheric environment is released in the process of producing these aqueous resins.

Formaldehyde is very toxic to the human body and various diseases occur when a person is exposed to formaldehyde of 30 ppm or more. According to the effect of formaldehyde concentration on the human body, irritation to the eyes, nose and throat below 0.1 ppm, and 0.25 to 0.5 ppm may cause severe asthma attacks in people with respiratory disorders and asthma. have. In the case of 2 to 5ppm, tears and severe pain are felt, and in the case of 10 to 20ppm, normal breathing becomes difficult, and the symptoms of cough / headache / heartbeat become faster.

More than 50 ppm, the upper limit of formaldehyde hearing aids, can cause inflammation of the lungs and acute poisoning symptoms such as dizziness / vomiting / diarrhea / convulsions and, in severe cases, can result in toxic emphysema. For example, according to a 1981 Schenke report, exposure of formaldehyde to air at 30 ppm for 1 minute can cause symptoms such as memory loss or mental distress, and inhalation of 100 ppm or more is fatal to the human body. Effect.

Meanwhile, water-based resins represented by thermosetting resins such as urea resins, melamine resins, and phenol resins are used as waterborne adhesives and applied to wood. For example, these water-based adhesives are used to bond building materials, insulation, interior materials, wooden furniture, silk wallpaper, and the like. Among them, these aqueous resins are essentially used as adhesives such as plywood, middle density board (MDF), particle board (PB, particle board) and the like. Formaldehyde gas is released from water-based resins used as adhesives for these wood products, resulting in various environmental pollution, including sick house syndrome.

Therefore, by reducing and suppressing the emission of formaldehyde gas generated when synthesizing and manufacturing the water-based resin, it is necessary to prevent environmental pollution represented by sick house syndrome and to promote a living environment that is harmless to the human body.

<Preceding technical literature>

<Patent Documents>

(Patent Document 1) Republic of Korea Patent Publication No. 10-2011-0069918

The present invention has been proposed to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a method for producing an environment-friendly water-based resin by excluding formaldehyde emission.

The present invention having the above-mentioned object is a method for producing an aqueous resin using formaldehyde as a monomer, comprising reacting a formalin aqueous solution with a first base component including a first urea, followed by a second urea. Reacting a second base component comprising a synthesis of a prepolymer; Synthesizing an aqueous resin by crosslinking the synthesized prepolymer; Treating the reaction product containing the synthesized aqueous resin with sodium sulfite (sodium sulfite); And it provides a method for producing an aqueous resin comprising the step of neutralizing the reaction product treated with sodium sulfite.

For example, the sodium sulfite (sodium sulfite) may be used as a crystal or an aqueous solution of sodium sulfite at a concentration of 10 to 30% (w / v).

At this time, the step of neutralizing the reaction product is an organic acid selected from the group consisting of formic acid (formic acid), fumaric acid, lactic acid, citric acid (citric acid), malic acid (malic acid), acetic acid (acetic acid), butyric acid, propionic acid and combinations thereof And treating the reaction product.

When synthesizing an aqueous urea resin according to one exemplary embodiment, the first base component comprises a first urea, the second base component comprises a second urea, and the prepolymer The synthesizing step may include reacting the formalin aqueous solution with the reactant containing the first urea at an alkaline condition at a temperature of 60 to 100 ° C. to obtain methylol urea, and alkaline the second urea to the obtained methylol urea. Under the conditions of addition, and cooling the reactor containing the first reaction product comprising the methylol urea and the second urea to a temperature of 55-75 ° C., and then adding an organic acid to the acidity of the first reaction product. Synthesizing the prepolymer by the reaction of the methylol urea and the second urea in a range of 6 to 6.5. The step of performing a crosslinking reaction of the prepolymer in a state in which the temperature of the reactor containing the synthesized prepolymer is cooled to a temperature of 10 to 40 ℃, and the second resin comprising an aqueous resin obtained by the crosslinking reaction Neutralizing the reaction product.

When synthesizing an aqueous melamine-urea resin according to another alternative embodiment, the first base component comprises a first urea and melamine, and the second base component comprises a second urea The synthesizing of the prepolymer may include obtaining a methylol urea by reacting the aqueous formalin solution with the reactant including the first urea in an alkaline condition at a temperature of 60 to 100 ° C., and melamine in the obtained methylol urea. Adding and performing a reaction between the methylol urea and the melamine while adjusting the pH of the first reactant including the methylol urea and the melamine to 7-9, and adding an organic acid 1 comprises the step of synthesizing the prepolymer by adding a second element in the acidity of the reactant is adjusted to 6 ~ 6.5, the step of synthesizing the aqueous resin, Performing a crosslinking reaction of the prepolymer in a state where the temperature of the reactor containing the pre-synthesized prepolymer is cooled to a temperature of 10 to 40 ° C, and neutralizing the second reaction product including the aqueous resin obtained by the crosslinking reaction. It may include the step of.

In the present invention, it is possible to exclude the generation of formaldehyde gas when producing a water-based resin by applying a chemical method. Through an economical and efficient process, Formaldehyde Emission Free Waterborne Adhesive can be manufactured that is completely excluded from the release of formaldehyde gas, and it is also possible to attach harmful substances such as formaldehyde even when attaching wooden floors, furniture, or silk wallpaper to buildings. Material does not occur.

As such, when the water-based resin and the water-based adhesive prepared by applying the process of the present invention, formaldehyde from water-based adhesives applied to solid wood flooring, construction materials, silk wallpaper, etc., made of wood such as plywood, medium density fiberboard, particleboard, etc. Is not discharged to the environment. Accordingly, interior materials using water-based resins can prevent and suppress sick house syndrome, which is known as a major factor, and contribute to an environment-friendly and well-being lifestyle.

1 is a flow chart schematically illustrating a process for producing a water-based urea resin synthesized according to an exemplary embodiment of the present invention.

2 and 3 are each a test report showing the residual amount of free formaldehyde in the water-based urea formaldehyde resin prepared according to an exemplary embodiment of the present invention.

The present inventors have completed the present invention in view of the fact that the formaldehyde gas generated in the synthesis of an aqueous resin using formaldehyde as a reaction material can be removed and blocked through a chemical process. EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail, referring drawings attached if needed.

1 is a flow chart schematically illustrating a process for producing a water-based urea resin synthesized according to an exemplary embodiment of the present invention. As shown in FIG. 1, according to the present invention, a method of manufacturing an aqueous resin in which formaldehyde gas is eliminated may be performed by reacting a first formalin aqueous solution with a first base component and a second base component of an aqueous resin. synthesizing and obtaining a prepolymer) (S110), synthesizing and obtaining an aqueous resin by curing the prepolymer (S120), and sodium sulfite (sodium sulfite, Na ₂ SO) in a reaction product containing the obtained aqueous resin. ₃ ) processing to remove the formaldehyde component contained in the product (step S130), and neutralizing the reaction product alkalized by the treatment of sodium sulfite (sodium sulfite) (step S140), optionally acidity Concentrating the product containing the adjusted aqueous resin (S150 step), and packaging and commercializing the concentrated aqueous resin (S160 step) .

As mentioned above, formaldehyde is used as a raw material component of the resin when producing an aqueous thermosetting resin such as urea resin, melamine resin, phenol resin and copolymers thereof. Accordingly, formaldehyde remains in the finally synthesized aqueous resin. As a method for removing formaldehyde released when preparing an aqueous resin, there may be a physical adsorption method using an adsorbent having an affinity for the remaining formaldehyde, or a method of applying a photoactive catalyst such as titanium oxide.

These physical adsorption methods and catalytic methods require expensive adsorbents or catalysts and are not preferable in view of economical process. In addition, formaldehyde adsorbed by physical adsorption may be emitted back to the surroundings due to changes in the surrounding environment, and the catalytic method should irradiate light of a specific wavelength band. Accordingly, in the present invention, formaldehyde gas, which is a toxic or harmful component remaining in the preparation and synthesis of the aqueous resin, is removed by applying a chemical method, so that formaldehyde gas is not discharged from the finally prepared aqueous resin.

First, a raw material for preparing an aqueous resin and, if necessary, a catalyst are added to a reactor to synthesize and obtain a prepolymer as a prepolymer (step S110). For example, the water-based resins prepared and synthesized according to the present invention include urea resins, melamine resins, phenolic resins and copolymers thereof containing formaldehyde components (e.g. melamine-urea resins, melamine-phenolic resins, or Alkylphenol-phenol resin).

In order to obtain a prepolymer for preparing an aqueous resin, an aqueous solution of formalin, which is a raw material of a formaldehyde component, and urea, melamine, phenol, and a mixed component thereof, which are base components of an aqueous resin, may be used. Functional additives may be added to facilitate or control the acidity (pH) of the reactants. For example, in order to synthesize | combine the prepolymer for obtaining urea resin or urea-melamine resin, it reacts with alkaline aqueous solution containing formaldehyde and 1st urea in alkaline conditions, putting it into a reactor and stirring. At this time, as the formalin aqueous solution may be used an aqueous formalin content of 30 to 60% by weight, preferably 35 to 50% by weight of formaldehyde.

The formalin aqueous solution and the first urea may be added in a molar ratio of approximately 1.5: 1 to 2.5: 1, and caustic soda (sodium hydroxide), caustic potassium (potassium hydroxide), calcium hydroxide and the like may be used to adjust the pH of the reactants to alkaline conditions. Alkali agents can be used. For example, when using sodium hydroxide as the alkalizing agent, 10 to 50% (w / v) aqueous sodium hydroxide solution can be added until the sodium hydroxide content is 1 to 5 parts by weight based on the total weight of the reactants. The acidity (pH) of the reactants thus changes to alkaline conditions of approximately 8.5 to 9.5, preferably 8.7 to 9.3.

In this case, the first formalin aqueous solution and the first urea react to increase the temperature of the reactor. In order to obtain a prepolymer, it may be preferable to react at a temperature of about 60 to 100 ° C., preferably 60 to 95 ° C. Formaldehyde (HCHO) and urea (O = C (NH ₂ )) contained in the aqueous solution of formalin react under alkaline conditions, and according to Scheme 1, methylol urea (OHCH ₂ NH) ₂ C = O) It is synthesized first.

Scheme 1

Then, in order to synthesize the prepolymer of urea resin, urea which is the second base component is added again, and the reaction temperature and the pH of the reactant are adjusted between methylol urea and the aqueous solution of formalin containing second urea and formaldehyde. Proceed with the reaction. At this time, when the polymerization reaction is started, the heating is stopped, the reaction proceeds while adjusting the reaction temperature and pH, and as the reaction proceeds, an organic acid may be added and the pH may be added and the reaction may be continued. In a preferred embodiment, the water solubility of the reactants being synthesized is continuously measured to reach the desired value and the polymerization reaction of the resin can be terminated in parallel with the neutralization process and the cooling process.

First, a second urea is added as a second base component to the methylol urea synthesized according to Scheme 1, and the reactor containing the first reaction product comprising methylol urea and the second urea is at a temperature of approximately 55-75 ° C. To cool. Such cooling can be performed using cooling water. The acidity of the first reaction product can then be adjusted in the range of approximately 6-6.5 by addition of an organic acid and obtained by the reaction of methylol urea and the second urea. The organic acid used to adjust the acidity of the first reaction product is not particularly limited, but is not limited to microacid (formic acid), fumaric acid, lactic acid, citric acid (citric acid), malic acid (malic acid), acetic acid (acetic acid), butyric acid, propionic acid and their It can be configured in combination.

The reaction of methylol urea with the second urea and formaldehyde under acidic conditions yields a linear soluble prepolymer. For example, the methylol group of methylol urea condenses to form an ether bond, or condensed with an amino group to form a methylene group. The ether group can be further heated to form methylene groups while releasing formaldehyde. Synthesis reaction of urea resin prepolymer from methylol urea can be represented by the following scheme 2.

Scheme 2

When the melamine-urea copolymer resin is to be synthesized, melamine is added to methylol urea, and the methylol urea and the above are adjusted in a state in which the pH of the first reactant including the methylol urea and the melamine is adjusted to 7-9. After performing the reaction of melamine, the prepolymer may be synthesized by adding an organic acid by adding a second element while the acidity of the first reactant is adjusted to 6 to 6.5.

Phenolic prepolymers for synthesizing phenolic resins react phenol and formaldehyde in a molar ratio of approximately 1: 0.7-1: 0.8 to produce o-methylol phenol or p-methylolphenol, which Methylolphenol reacts with phenol to form bis (hydroxyphenyl) methane, for example 2,4'-bis (hydroxyphenyl) methane or 4,4'-bis (hadihydroxyphenyl) methane. When the aqueous formalin solution containing formaldehyde is added to these bis (hydroxyphenyl) methanes again, a novolak prepolymer having a polynuclear phenol having approximately 5-6 benzene rings is synthesized via a methylol derivative.

Alternatively, resol prepolymers, which are multinuclear polyalcohols having approximately 3-4 benzene rings, may be synthesized by reacting excess formaldehyde with phenol at basic conditions. When synthesizing phenolic resins, cresol, resorcinol and furfural other than phenol may be used as modifications other than phenol. In addition, the prepolymer for synthesizing the melamine resin reacts with aqueous solution of formalin having formaldehyde and melamine, in which case the neutralized formaldehyde and melamine are reacted at approximately 60 to 100 ° C., for example, 80 to 100 ° C. to form a water-soluble methylol. Melamine (for example trimethylolmelamine or hexamethylolmelamine) is obtained.

When a prepolymer for synthesizing the aqueous resin is obtained, a crosslinking reaction between the prepolymers is performed to synthesize the aqueous resin in a polymer form (step S120). In one exemplary embodiment, when the urea resin is to be synthesized or the melamine-urea resin is to be synthesized, the temperature of the reactor containing the prepolymer synthesized in step S110 is approximately 10 to 40 ° C., preferably 15 to 15 °. Performing a crosslinking reaction of the prepolymer in a state of being cooled to a temperature of 35 ° C., and neutralizing a second reaction product including the aqueous resin obtained by the crosslinking reaction. Even in this case, cooling water may be used to cool the temperature of the reactor. The crosslinking reaction in urea resins and melamine-urea resins can be carried out under acidic conditions, for example, with the acidity adjusted to 6-6.5, for example 6.2-6.4.

On the other hand, when the melamine resin is to be synthesized, condensation reaction proceeds by heating methylolmelamine such as trimethylolmelamine or hexamethylolmelamine obtained in step S110 at approximately 80 to 100 ° C, and using cooling water or the like. Cooling to 캜 separates the hydrophobic melamine resin by resination. The main resin reaction is the condensation reaction of methylol-methylol and methylene bonds can be obtained. At this time, the resination is greatly affected by the pH of the reactant, and since the resination occurs at a minimum of pH 10 to 10.5, it may proceed at a lower or higher pH. In addition, in the case of a phenol resin, it may be synthesized by heating, reacting and / or adding a crosslinking agent to a prepolymer such as novolac and lexol synthesized in S110. In this case, formaldehyde may be added, but hexamethylenetetramine or paraformaldehyde may be used.

The aqueous resin synthesized through this process retains the formaldehyde component used as a raw material. Residual formaldehyde may be due to the unreacted formaldehyde (RF) used in synthesizing the prepolymer or water-based resin, and methylol, a prepolymer of urea resin, melamine-urea resin and melamine resin, is produced by forward reaction by reverse reaction. As the decomposed methyl group is decomposed by external conditions, the concentration of formaldehyde is increased, thereby allowing residual formaldehyde gas to be released to the outside.

Thereby, formaldehyde is released while being added to wood materials such as plywood using an aqueous resin composed of a formaldehyde component, for example, an urea resin. That is, the formaldehyde released at this time is unreacted formaldehyde remaining in the free state without reacting with the base component, or formaldehyde released as the dimethylene ether bond of the prepolymer or resin proceeds to the dimethylene bond during the curing process.

Thus, in the present invention, by treating the synthesized aqueous resin with sodium sulfite (sodium sulfite) chemically removes the unreacted residual formaldehyde and / or formaldehyde released during the curing process (step S130). In one exemplary embodiment, the content of residual formaldehyde component in the aqueous resin prepared through step S120 is analyzed to yield the content of residual unreacted formaldehyde, and the corresponding equivalent of sodium sulfite (sodium sulfite). By treating with, it is possible to completely remove the formaldehyde released from the water-based resin, including unreacted formaldehyde.

In one exemplary embodiment, sodium sulfite (sodium sulfite) may use anhydrous crystals. In one exemplary embodiment, when anhydrous sodium sulfite (sodium sulfite) crystals are injected into a reactor containing a reaction product comprising an aqueous resin, organic acids such as formic acid may be added to maintain the proper pH of the resin. have. By adding sodium sulfite (sodium sulfite) and treating the organic acid, formaldehyde remaining in the aqueous resin is removed as in Scheme 3 below.

Scheme 3

Subsequently, according to the treatment of sodium sulfite (sodium sulfite), the acidity of the reaction product of the aqueous resin from which the formaldehyde component has been removed is neutralized by neutralization (step S140). For example, the pH of the reaction product may be adjusted to approximately 6-8, preferably 7-8, for which an organic acid may be used. The type of organic acid that can be used is not particularly limited, but is selected from the group consisting of formic acid (formic acid), fumaric acid, lactic acid, citric acid (citric acid), malic acid (malic acid), acetic acid (acetic acid), butyric acid, propionic acid, and combinations thereof Can be.

Subsequently, the concentration of the solid content of the water-based resin in which the acidity is finally adjusted is about 60% or more (S150). The concentrated aqueous resin may have the advantage that curing can occur directly at room temperature. On the other hand, in the case of the non-condensed aqueous resin, it must be heated for curing. Subsequently, the producting process is performed by performing a process such as packaging (step S160).

The aqueous resin prepared according to the present invention and the aqueous adhesive obtained therefrom chemically removed formaldehyde released during the production process. This completely suppresses the release of formaldehyde gas, which is harmful to the human body, from the aqueous resin finally produced according to the present invention. Conventionally, by suppressing the release of formaldehyde gas caused in the process of bonding the wood material using the water-based resin, it is possible to solve the problem of sick house syndrome, and to pursue well-being in an environment-friendly environment.

Hereinafter, the present invention will be described in more detail with reference to exemplary embodiments.

Example 1 Preparation of Aqueous Urea Resin

3 mol of 50% formalin aqueous solution was put into a reactor equipped with a stirrer, heated to 45 ° C. while stirring, and 2 mol of urea was added to dissolve it. When 25% aqueous sodium hydroxide solution is injected into the reactor to react the formalin aqueous solution with urea, the temperature of the reactant is increased to 85 ° C. by self-exothermic reaction. Further heating and holding at 95 ° C. for 90 minutes yields a cyclic prepolymer. In this process, 25% caustic soda solution was injected again to adjust the pH to 8.7 ~ 9.3.

An additional 0.3 mole of urea was added and maintained for 10 minutes while maintaining the temperature of the reactor at 85 ° C, and maintained for 25 minutes while adjusting the pH of the reaction to 6.2-6.4. After 15 minutes the temperature of the reactor was cooled to 75 ° C. and after 7 minutes the temperature of the reactor was cooled to 40 ° C. Thereafter, the pH was adjusted to 7.4 and the resin was sampled to determine the residual formaldehyde content by measuring the content of residual formaldehyde. In this case, cooling was performed slowly to inject 0.05 mol of sodium sulfite (sodium sulfite) while adjusting the temperature so that the temperature did not rise due to the reaction heat generated during the reaction of sodium sulfite. At this time, the pH was adjusted by treating with formic acid to maintain 7.4.

Example 2 Preparation of Aqueous Urea-Melamine Modified Resin

Inject 3 mol of 37% formalin aqueous solution into the reactor equipped with a stirrer, heat it with stirring to maintain 60 ° C, and evenly add 1 mol of urea at 1 minute intervals, and then inject 25% aqueous sodium hydroxide solution to pH 8 of the reaction product. Reaction was carried out while maintaining to produce a prepolymer. After 30 minutes, 0.2 mol of melamine was added thereto, and the urea-melamine resin was synthesized while adjusting to pH 8 at 80 ° C.

Subsequently, 0.4 mole of urea was added three times at 20-minute intervals while adjusting the pH of the reaction product to 6 to react for 150 minutes, and the reaction resin was rapidly cooled to 30 ° C to terminate the polymerization reaction. At this time the pH of the product was maintained at 6. Synthesized resin was collected to determine the content of 0.5% by analyzing the residual formaldehyde content. After cooling, 0.016 mol of steric anhydrous sodium sulfite (sodium sulfite) was added and stirred for 30 minutes while adjusting the temperature of the reactant to be maintained without raising the reaction temperature due to the reaction heat generated during the reaction of sodium sulfite. Adjusted to maintain 6.8.

2 and 3 are test report tables showing the residual amount of free formaldehyde of the aqueous resin synthesized in Examples 1 and 2, respectively. As can be seen in Figures 2 and 3, it was confirmed that no formaldehyde gas was discharged to the aqueous resin synthesized in the embodiment of the present invention.

In the above description, but limited to the preferred embodiments of the present invention, but this is only an example, the present invention is not limited to this may be modified and carried out in various ways, and further technical features based on the technical spirit disclosed It will be apparent that it can be implemented in addition.

Claims (4)

1. As a method for producing an aqueous resin using formaldehyde as a monomer component,

   Reacting the aqueous formalin solution with a first base component comprising a first urea followed by reacting a second base component comprising a second urea to synthesize a prepolymer;

   Synthesizing an aqueous resin by crosslinking the synthesized prepolymer;

   Treating the reaction product containing the synthesized aqueous resin with sodium sulfite (sodium sulfite); And

   Neutralizing the reaction product treated with sodium sulfite;

   The synthesizing of the prepolymer may include reacting the formalin aqueous solution with the reactant containing the first urea at an alkaline condition at a temperature of 60 to 100 ° C. to obtain methylol urea, and the second urea to the obtained methylol urea. Adding in an alkaline condition, cooling the reactor containing the first reaction product containing the methylol urea and the second element to a temperature of 55 ~ 75 ℃, and then adding the organic acid to the first reaction product Synthesizing the prepolymer by the reaction of the methylol urea and the second urea with an acidity of from 6 to 6.5,

   Synthesizing the aqueous resin may include performing a crosslinking reaction of the prepolymer in a state where the temperature of the reactor containing the synthesized prepolymer is cooled to a temperature of 10 to 40 ° C., and the aqueous resin obtained by the crosslinking reaction. Neutralizing a second reaction product comprising a method of producing a water-based resin.
2. As a method for producing an aqueous resin using formaldehyde as a monomer component,

   Reacting the aqueous formalin solution with a first base component comprising a first urea and melamine, followed by reacting a second component comprising a second urea to synthesize a prepolymer;

   Synthesizing an aqueous resin by crosslinking the synthesized prepolymer;

   Treating the reaction product containing the synthesized aqueous resin with sodium sulfite (sodium sulfite); And

   Neutralizing the reaction product treated with sodium sulfite;

   The synthesizing of the prepolymer may include obtaining a methylol urea by reacting the formalin aqueous solution with the reactant including the first urea at an alkaline condition at a temperature of 60 to 100 ° C., and adding melamine to the obtained methylol urea. And performing a reaction between the methylol urea and the melamine in a state where the pH of the first reactant including the methylol urea and the melamine is adjusted to 7-9, and adding an organic acid to the first reaction. Synthesizing the prepolymer by adding a second element with the acidity of the reactants adjusted to 6 to 6.5,

   Synthesizing the aqueous resin may include performing a crosslinking reaction of the prepolymer in a state where the temperature of the reactor containing the synthesized prepolymer is cooled to a temperature of 10 to 40 ° C., and the aqueous resin obtained by the crosslinking reaction. Neutralizing a second reaction product comprising a method of producing a water-based resin.
3. The method according to claim 1 or 2,

   The neutralizing of the reaction product may include reaction of an organic acid selected from the group consisting of formic acid (formic acid), fumaric acid, lactic acid, citric acid (citric acid), malic acid (malic acid), acetic acid (acetic acid), butyric acid, propionic acid, and combinations thereof. A method of making an aqueous resin comprising the step of treating the product.
4. The method according to claim 1 or 2,

   The sodium sulfite (sodium sulfite) is a crystal or a method for producing an aqueous resin, characterized in that an aqueous solution of sodium sulfite (sodium sulfite) at a concentration of 10 to 30% (w / v) is used.

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