KR100223398B1 - Thermosetting impregnation sheet used for coating and method for manufacturing the same - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

Thermosetting impregnated paper for painting and its manufacturing method

2. The technical gist of the invention

The present invention changes the reaction catalyst TEA used in the LPM resin to sodium hydroxide (NaOH) and adjusts the formalin and melamine at a predetermined ratio, thereby producing a method for producing an environmentally friendly melamine resin for excellent moisture resistance and an impregnating paper for coating using the same. The purpose is to provide a manufacturing method.

3. Summary of Solution to Invention

The present invention comprises the steps of impregnating a base resin mounted on a roll coated paper in a first impregnating tank having a thermosetting resin in which a predetermined resin is infiltrated; Contacting the knife through the first paper impregnating tank at a predetermined pressure to remove resin on both surfaces of the paper to remove pores; Impregnating the first dried base paper in a second impregnation tank in which a thermosetting resin is embedded such that the resin penetrates into the fiber tissue of the base paper; Controlling the amount of resin applied on the surface of the base paper by passing the paper impregnated twice between the pressing rollers; Passing between the smoothing roller to maintain the smoothness of the resin coating amount; Second drying by passing the base paper through a drying chamber partitioned into a predetermined zone having a temperature deviation; And it provides a method for producing impregnated paper and sedimentation paper produced by the step of cooling the secondary dried raw paper to a predetermined temperature.

In addition, the resin used in the impregnated paper manufacturing method, the resin contained in the first impregnating tank is melamine 42.8 ~ 43.7wt%, formalin 43.2 ~ 44.1wt%, water 12.8 ~ 13.7% and the reaction catalyst sodium hydroxide (NaOH) 0.3 3 ~ 6wt% of urea, 3 ~ 6wt% of DEG, 2 ~ 3wt% of methanol, 2 ~ 3wt% of methanol, 0.2 ~ 0.5wt% of epoxy resin, and 1.0 ~ 1.2wt% of sodium hydroxide (NaOH) Melamine resin prepared by mixing and formalin 59.3 ~ 60.5wt%, urea 24 ~ 25.2wt%, distilled water 15 ~ 16.2% and sodium hydroxide (NaOH) of any one of the urea resin prepared by mixing Resin is inherent, and the above-mentioned melamine resin is inherent in the second impregnation tank.

4. Important uses of the invention

Eco-friendly melamine resin is manufactured and thermally bonded to particle board or medium density fiber board without any adhesive so that surface layer with excellent paintability can be obtained.

Description

Thermosetting impregnated paper for painting and its manufacturing method {THERMOSETTING IMPREGNATION SHEET USED FOR COATING AND METHOD FOR MANUFACTURING THE SAME}

The present invention relates to an impregnated paper used as a surface material for household furniture, kitchen furniture, office furniture, tables, interiors, and the like, and a method of manufacturing the same, and in particular, to prepare a melamine resin or urea resin for painting excellent in moisture resistance, and the melamine resin Or thermosetting impregnating paper for painting and impregnating a predetermined sheet of urea resin and drying it, and then adhering to a particle board or a medium-density fiber board without a separate adhesive under pressure, and coating the surface. It is about.

In general, in order to manufacture a plate used for wooden furniture such as general furniture, tables, musical instruments, etc. to be durable, it is manufactured by applying a thin coating of phenolic resin for bonding phenolic paper on both sides of the plywood, and placing the phenolic paper on it and heat-pressing it to a predetermined temperature. Doing. However, such a plate has to go through a number of manufacturing processes, and also takes a lot of manufacturing time, which leads to a problem of lowering productivity. Particularly, phenolic paper and plywood are bonded by urea resin. As a result, there is a problem that often occurs when the phenolic paper is released.

In order to solve such a problem, conventionally, in the patent publication 95-13293, 45 wt% to 50 wt% of phenol, 45 wt% to 48 wt% of formalin as an adhesive, and 1 wt% to caustic soda and ammonia as stabilizers for thermosetting resins as catalysts. The impregnated tank containing 2 wt% synthetic phenol was passed through kraft paper dried with 3% to 5% moisture content to obtain impregnated paper impregnated with synthetic phenol, and a knife was attached to one surface of the impregnated paper to remove synthetic phenol. Impregnated paper for producing a durable plate and a method for producing the impregnated paper have been proposed by applying an unsaturated fatty acid such as paraffin having a solid content of about 50% on the back surface of the impregnated paper after drying.

However, in the conventional kraft paper impregnated with phenolic resin and then impregnated with a hot plate formed on a plate and its manufacturing method, since the phenolic resin is oily, it is limited to kraft paper, and general LPM paper is aqueous. Not only is it impossible, but you can't put a pattern in either water or oil.

In addition, during the In Lay (Painting Inlay) work, which is a substitute for veneer, the residues generated in the cutting process may be stuck, and if two sheets are overlapped when the veneer is formed, there is a problem that marks are formed on the overlapped portions.

In addition, the phenol acts as a culprit of environmental pollution and is not only dangerous in use, but also restricted in post-treatment, and has a poor adhesive strength when forming into a sheet after manufacture of the phenolic resin. This is a long time inefficient production, severe phenol odor, shortened mirror plate life is inherent, and is mainly applied to medium-density fiber board, there was a problem that must depend only on the direct cost increase factor and kraft paper .

In addition, the production of general LPM resin (Low Press Melamine resin) used for the production of gravure paper or monochromatic paper is made by adding formalin (61.6 wt%), melamine (33.3 wt%) and distilled water (3.8%) to the reactor at room temperature. TEA (1.3 wt%) was added as a catalyst, and the pH was adjusted to 8.3 to 8.5, followed by heating to 70 ° C. When the temperature reaches 70 ° C., urea (12 wt%) is added and the reaction proceeds while maintaining the temperature at 70 ° C., and after 50 to 60 minutes, 25 ° C. distilled water and LPM resin are mixed at 4: 1 in the mass cylinder. If cloudy occurs, cool to room temperature. When the temperature reaches 60 ° C during cooling, sugar (2.5 wt%) is added, DEG (diethylene glycol) (2.4 wt%) and methanol (3.0 wt%) are added at room temperature, and sodium hydroxide (0.8-1.9 wt%) is added thereto. The pH is adjusted to 9.0 to 9.2 to complete. The LPM resin prepared as described above was impregnated with a base paper after mixing 03 to 0.5 wt% of a curing agent, 0.4 to 0.8% of a releasing agent, and 0.5 to 1.0 wt% of a dispersant.

In the case of manufacturing impregnated paper using such LPM resin, the loaded impregnated paper is difficult to feed sheet when printing due to self-adhesion during press molding operation. In addition, the impregnated paper using the conventional LPM resin has no adhesive force, so it is not possible to paint LPM paper with wood paints or paints, but also has poor moisture resistance and not 100% coating. Problems such as peeling of the castle and yellowing occurred.

On the other hand, when using wood in the out-lay and In-Lay coating work, which is the work of pasting wood or veneer, it is replaced by veneer because of the high cost burden. While minimizing the savings, we are designing using a variety of objects using the fitting method, but in the case of the mosaic method, the cost burden is high due to the high limits and loss ratios of various color expressions, and it is difficult to supply the same materials. Rather, there is a problem of purchasing expensive equipment (laser). In addition, some of the conventional LPM sheet used to replace the veneer, but when produced by the inlay and inlay method, there is a problem due to the poor adhesion due to the adhesion of the sheet and the sheet and unstable surface coating after sheet molding.

Therefore, the present invention has been made to solve the above problems, by changing the reaction catalyst TEA used in the LPM resin to sodium hydroxide (NaOH) and by adjusting the formalin and melamine in a predetermined ratio environmentally friendly excellent moisture resistance Its purpose is to provide a melamine resin for painting and a method of manufacturing the same.

In addition, the present invention can be applied to all LPM and base paper for HPM, and another object of the present invention is to provide a melamine resin for painting and its manufacturing method to replace the existing veneer with a paper impregnated paper.

In addition, the present invention improves the adhesion between the sheet and the sheet, to enable the surface coating after forming the sheet, and the impregnated paper for painting and the manufacturing method thereof so that the plate formed by the impregnated paper can be used as a finishing material as it is. There is another purpose in providing.

In addition, the present invention has another object to provide a coating impregnated paper for improving the cost and environmental problems by minimizing the coating process by enabling the coating operation to be a one-time transparent coating.

1 is a schematic view showing a thermosetting impregnated paper manufacturing process for coating according to the present invention.

* Explanation of symbols for main parts of the drawings

1: paper roll 2: height adjustment roller

3: first impregnation tank 4: knife

5: infrared heater 6: second impregnation tank

7: pressure roller 8: smoothing roller

9: drying chamber 10: cooling chamber

11: cooling roller 12: cutting machine

13: feed roller

In order to achieve the above object, the present invention, in the impregnated paper manufacturing method using a thermosetting resin for coating, by impregnating the base paper attached to the roll core in the first impregnating tank in which one of the melamine resin or urea resin is embedded, the melamine resin or Allowing urea resin to penetrate; Contacting the knife through the first paper impregnating tank at a predetermined pressure to remove resin on both surfaces of the paper to remove paper holes; First drying the raw paper surface from which the resin has been removed by an infrared heater; Impregnating the primary dried paper in a second impregnation tank in which melamine resin is embedded to allow the melamine resin to penetrate into the fiber tissue of the paper; Controlling the amount of resin applied on the surface of the base paper by passing the paper impregnated twice between the pressing rollers; Passing between the smoothing roller to maintain the smoothness of the resin coating amount; Second drying by passing the base paper through a drying chamber partitioned into a predetermined zone having a temperature deviation; And it provides a method for producing impregnated paper comprising the step of cooling the secondary dried raw paper to a predetermined temperature.

In addition, the present invention is a resin used in the impregnated paper manufacturing method, the resin contained in the first impregnating tank is melamine 42.8 to 43.7 wt%, formalin 43.2 to 44.1 wt%, water 12.8 to 13.7% and the reaction catalyst sodium hydroxide ( NaOH) 0.3 to 1.2 wt% of the co-condensed resin mixed with 3-6 wt% of urea, DEG (diethylene glycol) 2-3 wt%, methanol 2-3 wt%, epoxy resin 0.2-0.5 wt% and sodium hydroxide ( Melamine resin prepared by mixing 1.0-1.2 wt% of NaOH, 59.3-60.5 wt% of formalin, 24-25.2 wt% of urea, 15-16.2% of distilled water, and 0.5-1.7 wt% of sodium hydroxide (NaOH). It is condensed, and the resin of any one of the urea resin prepared by mixing 11-12 wt% of urea and 0.6-1.6 wt% of sodium hydroxide (NaOH), and the above-mentioned melamine resin is embedded in the second impregnation tank It is done.

In addition, the present invention provides a sheet using the impregnated paper in the case of hot-pressure molding the impregnated paper according to the manufacture as described above to the temperature of 160 to 220 ℃, pressure 180 to 310 bar, time 30 to 80 seconds.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention;

1 is a schematic view showing a thermosetting impregnated paper manufacturing process for coating according to the present invention.

In the drawings, 1 is a paper roll, 2 is a height adjusting roller, 3 is a first impregnation tank, 4 is a knife, 5 is an infrared heater, 6 is a second impregnation tank, 7 is a pressure roller, 8 is a smooth roller, 9 is a drying chamber, 10 shows a cooling chamber, 11 shows a cooling roller, 12 shows a cutter, and 13 shows a conveying roller.

The thermosetting impregnated paper for painting according to the present invention and a method for manufacturing the same are prepared by manufacturing a melamine resin for painting as a surface material used for general furniture and the like and impregnating it in a base paper to enable surface coating after molding of a sheet. The thermosetting melamine resin for coating to impregnate the monochromatic paper is mixed with 42.8-43.7 wt% of melamine as a main reactant, 43.2-44.1 wt% with formalin, 12.8-13.7% with distilled water, and 0.3-1.2 wt% of sodium hydroxide (NaOH) as a reaction catalyst. To 86.3-91.8 wt% of the co-condensed resin to form urea 3.0 to 6.0 wt%, DEG 2.0 to 3.0 wt%, and methanol 2.0 to 3.0 wt%.

Such melamine resin can be used as a finishing material when manufacturing the sheet by impregnating the base paper by the environmentally friendly action, it can be obtained excellent quality even as the first top finish when painting. In addition, various patterns can produce a natural texture of solid wood texture and high sensitivity of gorgeous solid, marble, metal texture, and can reduce the existing painting work process.

The method of manufacturing the thermosetting melamine resin for coating as described above is as follows.

first. 42.8 to 43.7 wt% of melamine, the main reactant, 43.2 to 44.1 wt% of formalin, 12.8 to 13.7% of distilled water, and 0.3 to 1.2 wt% of sodium hydroxide (NaOH) as the reaction catalyst are added and stirred.

Then, after heating the stirred resin to 80 ℃ ~ 90 ℃ co-condensation by proceeding the reaction for 40 to 60 minutes, dilute the resin condensed in distilled water at 25 ℃ in a 3: 1 ratio, which is the This is to confirm that the reaction of the resin is completed, and when the cloudy resin appears in the diluted resin, the resin is cooled to 18 to 20 ° C within 40 minutes.

In the cooling process, 3-6 wt% of urea was added to 86.3-91.8 wt% of the resin for viscosity control, and when the temperature was reached, DEG 2-3 wt%, methanol 2-3 wt%, epoxy 0.2-0.5 wt% and sodium hydroxide ( NaOH) is further added 1.0-1.2%.

The co-condensed resin is then aged and stored in a storage tank for 12 hours or more, when the physical properties of the resin are maintained at specific gravity of 1.215 to 1.220, pH 8.5 to 9.5, and solid content of 54 to 56%. Lasts for hours.

The thermosetting melamine resin prepared as described above is mixed with 0.3 to 0.6 wt% of a curing agent, 0.3 to 0.5 wt% of a releasing agent and a dispersant before use, and used in an impregnation bath.

Herein, the release agent is easily released when the melamine resin is hot-pressed in a sheet, and the dispersing agent is to improve the flow of the resin in the thermocompression bonding process and to obtain a desired surface.

The manufacturing method of the impregnated paper using the thermosetting melamine resin will be described with reference to FIG. 1.

As shown in the drawing, a base paper such as 60-160 g / m 2 gravure printing paper or 60-160 g / m 2 monochromatic paper wound on the roll 1 is passed through the first impregnation tank 3 containing primary melamine resin. . At this time, while adjusting the height of the height adjustment roller (2) to allow the melamine resin to fully penetrate the base paper.

Then, the base paper having passed through the first impregnation tank 3 is removed by the knife 4 in contact with both surfaces thereof, wherein the amount of resin applied to the base paper surface according to the contact pressure of the knife 4. To adjust. The contact pressure of the knife 4 in this embodiment has a contact pressure such that the paper hole inside the fiber tissue of the paper can be completely removed. When the paper hole of the original paper is completely removed, it is dried by passing through an infrared heater 5 at 100 to 120 ° C., and dried to maintain a moisture level of 13 to 14%, and then a second impregnating tank having a secondary melamine resin ( Pass 6). The primary dried base paper is coated with a secondary melamine resin, in which the present example shows an example using primary and secondary melamine resins to have a perfect coating component in secondary impregnation, but is not limited thereto. Primary urea resins and secondary melamine resins may also be used, and in this case, the same thermosetting coating impregnated paper as in the former may be obtained.

Here, the primary urea resin is prepared as follows.

First, 59.3-60.5 wt% of formalin, 24-25.2 wt% of urea, and 15-16.2% of distilled water were added, and 0.5-1.7 wt% of sodium hydroxide (NaOH) was added to adjust the pH to 5.5-6.5. Heat to 80-90 degreeC.

The reaction was carried out at 80 to 90 ° C. for 40 to 60 minutes to dilute distilled water at 20 ° C. in a ratio of 1: 3 to the co-condensed resin.

When the cooling process reaches 45-50 ° C., 11-12 wt% of urea is added to 87.4-89.4 wt% of co-condensed resin, and 0.6-1.6 wt% of sodium hydroxide (NaOH) is added to pH 8.5-9.0. To prepare.

The urea resin thus prepared has physical properties of specific gravity of 1.170 to 1.180, pH 8.5 to 9.0, and solid content of 46 to 48%, and stability of the resin for 200 to 240 hours is maintained.

In the present invention, by impregnating primary and secondary melamine resins twice, or impregnating primary urea resins and secondary melamine resins, the resin does not sufficiently infiltrate into the internal tissue of the base plate by conventional impregnations. The problem that the adhesive force and the wear property of the surface fall when adhere | attached to this was solved.

The base paper impregnated twice through the second impregnation tank 6 is passed through the compression roller (7) capable of adjusting the fine gap between the two rollers to adjust the amount of impregnation according to the characteristics of the base paper. That is, the pressing roller 7 is pressed so that the desired amount of resin is applied to the base paper. In addition, while passing the base paper through the smoothing roller 8 mounted on one side of the pressing roller 7 to maintain the smoothness of the resin amount.

The base paper that has passed through the smoothing roller 8 has a temperature deviation for each zone and is dried while passing through a drying chamber 9 of a hot air circulation type. The drying chamber (9) is composed of four zones, each zone sequentially drying the base paper having 100 ℃, 120 ℃, 130 ℃, 140 ℃. At this time, the traveling speed of the paper passing through the drying chamber 9 is to be maintained 20 to 30m / min. The raw paper that has passed through the drying chamber 9 is completely cooled while passing through the cooling chamber 10 and the cooling roller 11, and in this case, the primary cooling chamber 10 is cooled to 40 to 50 ° C., and further inside the roll. The secondary cooling roller 11 through which the cooling water flows to be completely cooled to 20 to 30 ° C. when the base paper passes. The cold finished paper is cut by the cutter 12 for each specification to obtain a coating impregnated paper excellent in thermosetting.

The impregnated paper prepared as described above is used for one-time finishing of particle boards or medium density fiberboards. In this case, when the impregnated papers are thermoformed on a sheet such as the particle boards or medium density fiberboards by a single cycle press or multiple presses, The conditions are temperature 160 ~ 220 ℃, pressure 180 ~ 310bar, time 30 ~ 80 seconds, this condition may be some deviation depending on the characteristics of the impregnated paper, sheet thickness, press performance, wherein the melamine resin layer during the molding It is completely adhered to the sheet while being thermally cured, and a surface layer having excellent adhesion with wood paints can be obtained.

As described above, the melamine resin used in the impregnated paper may be used in silkscreen products or UV and hygroscopic coatings. First, when the resin of the present invention is used in the former silkscreen products, that is, an epoxy resin having a strong adhesive force And by using the silk screen technique on the product molded in urethane resin, it is possible to commercialize, and can improve the quality of the product such as wear resistance, stain resistance by one transparent coating. In particular, various products such as paintings (orient paintings, western paintings), corporate trademarks, logos, and photographs can be displayed, and various designs using existing computer graphics can be performed at low cost.

In addition, the surface coating effect in the latter U.V coating or high-gloss coating is as follows.

Conventional methods such as UV coating, high gloss painting, brush painting, spray painting, roll coating, cut ten coater, etc. As a result, the resin of the present invention can be used as a one-time transparent coating to reduce the cost by reducing the coating process of up to six steps depending on the product, and the environmental pollution problem is also improved.

The present invention described above is not limited to the above-described embodiment and the accompanying drawings, and various substitutions, modifications, and changes are possible within the scope without departing from the technical spirit of the present invention. It will be apparent to those who have knowledge.

As described above, according to the present invention, all the LPM and HPM base papers can be applied by manufacturing an environmentally friendly coating melamine resin and manufacturing impregnated paper having enhanced chemical resistance, water resistance, heat resistance, durability, etc. Improved adhesion between sheets, surface coating after sheet forming, and can replace costly paper by using impregnated paper for painting, reducing cost to less than 1/2, and mass production as supply of same material is possible. Has the effect.

Claims (18)

(correction) In the manufacturing method of impregnated paper using a thermosetting resin for painting, A first step of impregnating the first sheet impregnated with one of the melamine resin or the urea resin into the roll core to infiltrate the melamine resin or the urea resin; A second step of removing the paper holes by removing the resin on both surfaces of the paper by contacting the knife at a predetermined pressure with the paper passing through the first impregnation tank; A third step of heating the original surface from which the resin has been removed by an infrared heater to dry firstly; A fourth step of impregnating the primary dried paper in a second impregnation tank in which melamine resin is embedded to allow the melamine resin to penetrate into the fiber tissue of the paper; A fifth step of controlling the amount of resin applied on the surface of the base paper by passing the base paper impregnated twice between the pressing rollers; A sixth step of maintaining the smoothness of the resin coating amount by passing through the smoothing rollers; A seventh step of drying the paper by passing it through a drying chamber partitioned into a predetermined zone having a temperature deviation; And Eighth step of cooling the secondary dried paper to a predetermined temperature Impregnated paper manufacturing method comprising a. (delete) (correction) The method of claim 1, The melamine resin was mixed with 42.8 to 43.7 wt% of melamine, 43.2 to 44.1 wt% of formalin, 12.8 to 13.7% of water, and 0.3 to 1.2 wt% of sodium hydroxide (NaOH) as a reaction catalyst. Method for producing impregnated paper, characterized in that the urea is prepared by mixing 3-6wt%, DEG 2-3wt%, methanol 2-3wt%, epoxy resin 0.2-0.5wt% and sodium hydroxide (NaOH) 1.0-1.2wt% . The method of claim 3, wherein The melamine resin has a specific gravity of 1.215 to 1.220, pH 8.5 to 9.5, solid content of 54 to 56 wt% characterized in that the impregnated paper manufacturing method. The method of claim 1, The urea resin was mixed with 59.3 to 60.5 wt% of formalin, 24 to 25.2 wt% of urea, 15 to 16.2% of distilled water, and 0.5 to 1.7 wt% of sodium hydroxide (NaOH). 11 to 12wt%, sodium hydroxide (NaOH) 0.6 to 1.6wt% of the impregnated paper manufacturing method characterized in that it was prepared by mixing. The method of claim 5, The urea resin is a method for producing impregnated paper, characterized in that the urea resin having physical properties of specific gravity 1.170-1.180, pH 8.5-9.0, solid content 46-48wt%. (correction) The method according to claim 1 or 3, The melamine resin is a manufacturing method of impregnated paper, characterized in that the mixture is added 0.3 ~ 0.6wt% of the curing agent, 0.3 ~ 0.5wt% of the release agent and dispersant. (correction) The method according to claim 1 or 3, The third step is impregnated paper manufacturing method characterized in that for controlling the temperature of the heater to 100 to 120 ℃ so that the moisture level of the resin is maintained 13 to 14%. (correction) The method according to claim 1 or 3, The seventh step is a method of manufacturing impregnated paper, characterized in that the drying process proceeds to 20 ~ 30m / min the base paper to the zone of each drying chamber having a temperature of 100 ℃, 120 ℃, 130 ℃, 140 ℃. (correction) The method according to claim 1 or 3, The eighth step is the impregnation, characterized in that the first cooling to 40 ~ 50 ℃ in the cooling chamber, passing through the first cooled paper between the cooling roller flowing the cooling water to the second cooling to 20 ~ 30 ℃ Manufacturing method. (correction) An impregnated paper produced by any one of claims 1 to 10. (delete) (correction) A first step of adding and stirring 42.8 to 43.7 wt% of the main reactant melamine, 43.2 to 44.1 wt% of formalin, 12.8 to 13.7% of distilled water, and 0.3 to 1.2 wt% of sodium hydroxide (NaOH) as a reaction catalyst; A second step of heating the stirred resin at 80 ° C. to 90 ° C. and then performing a reaction for 40 to 60 minutes to co-condense; A third step of cooling the co-condensed resin to a room temperature of 18 to 20 ° C. within 40 to 50 minutes; A fourth step of adjusting the viscosity by adding 3.0 to 6.0 wt% of the cooled resin 86.3 to 91.8 wt%; A fifth step of adding 2.0 wt% to 3.0 wt% of E.D.G, 2.0 wt% to 3.0 wt% of methanol, 0.2 wt% to 0.5 wt% of epoxy resin, and 0.6 wt% to 1.6 wt% of sodium hydroxide; And A sixth step of aging the co-compressed resin in a storage tank for at least 12 hours Method for producing a melamine resin for impregnated paper production, comprising a. (correction) The method of claim 13, In order to confirm whether the reaction of the resin is completed after the second step, diluting the distilled water of 20 ~ 25 ℃ to 1: 3 in the co-condensation resin, when the turbidity appears further characterized in that it further comprises a seventh step of cooling Method for producing a melamine resin for impregnated paper production. (correction) A first step of adding 59.3 to 60.5 wt% of formalin as a main reactant, 24 to 25.2 wt% of urea, and 15 to 16.2% of distilled water; Adding 0.5 to 1.7 wt% of sodium hydroxide (NaOH) to adjust pH to 5.5 to 6.5, and heating to 80 to 90 ° C. for co-condensation while performing a reaction for a predetermined time; A third step of continuously adjusting 0.6-1.6 wt% of sodium hydroxide to maintain the co-condensed resin at 80-90 ° C. to pH 8.5-9.0; A fourth step of cooling the co-condensed resin; And A fifth step of adding 11-12 wt% of urea to 87.4-89.4 wt% of resin when it reaches 45-50 ° C. in the cooling process Method for producing a urea resin for impregnated paper production, comprising a. (correction) The method of claim 15, In order to check whether the reaction of the resin is completed after the second step, dilution of 20 ~ 25 ℃ distilled water in 1: 3 in the co-condensation resin and when the turbidity appears further characterized in that it further comprises a sixth step of cooling Method for producing urea resin for impregnated paper manufacturing. (correction) The method of claim 16, The sixth step A method for producing urea resin for impregnating paper, comprising the step of cooling to room temperature. (correction) The sheet produced using impregnated paper for coating, characterized in that the impregnated paper of claim 11 is thermo-formed, and the hot pressure condition is set at a temperature of 160 to 220 ° C., a pressure of 180 to 310 bar, and a time of 30 to 80 seconds.

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