KR101017870B1 - Manufacturing method of melamine-urea-formaldehyde resin adhesive for medium density fiberboards - Google Patents

Abstract

The present invention relates to a method for producing a melamine-urea-formaldehyde resin adhesive for producing a medium density fiber board and a method for producing a medium density fiber board using the adhesive prepared by the above method. While manufacturing melamine-urea-formaldehyde resin adhesive for fiber board manufacturing, while producing a medium density fiber board using the adhesive thus prepared, the amount of formaldehyde released is not reduced to KS standard super E0 (Super E0). It relates to a method for producing a melamine-urea-formaldehyde resin adhesive for producing a medium density fiber board which can be reduced to) and a method for producing a medium density fiber board using the adhesive prepared by the above method.

Medium Density Fiberboard, Melamine-Urea-Formaldehyde Resin Adhesive, Formaldehyde Release

Description

Manufacturing method of melamine-urea-formaldehyde resin adhesive for medium density fiberboards}

The present invention relates to a method for producing a melamine-urea-formaldehyde resin adhesive for producing a medium density fiber board and a method for producing a medium density fiber board using the adhesive prepared by the above method. While manufacturing melamine-urea-formaldehyde resin adhesive for fiber board manufacturing, while producing a medium density fiber board using the adhesive thus prepared, the amount of formaldehyde released is not reduced to KS standard super E0 (Super E0). It relates to a method for producing a melamine-urea-formaldehyde resin adhesive for producing a medium density fiber board which can be reduced to) and a method for producing a medium density fiber board using the adhesive prepared by the above method.

Medium density fiber board has a density which is produced through a molding, hot-press by applying an adhesive to the wood fiber is obtained by fibrillation of wood raw material at a high temperature and the plate-like products of the wood-0.35~0.85g / cm ^3, a thickness is capable of producing up to and 2.5~35mm It is widely used in all areas of furniture used for interior construction finishing or indoors because it can be complicated machining.

When manufacturing such a medium-density fiber board, urea-formaldehyde resin adhesive or melamine-urea-formaldehyde resin adhesive, such as colorless, excellent adhesion and low cost, is widely used. Formaldehyde is slowly released upon contact, which is known to be harmful to humans when using the product.

Particularly, since medium density fiberboard is mainly used indoors, it is known that the adhesive used in manufacturing medium density fiberboard affects indoor air quality and directly affects human health. Various laws and regulations have been enacted and enforced, and the Indoor Air Quality Control Act is currently in force in Korea.

Therefore, one of many efforts to reduce the amount of formaldehyde emissions of wood-like products is an effort to change the components, additives and the like of the adhesive.

On the other hand, US Patent No. 4,997,905 in the prior art related to the present invention was able to produce a low formaldehyde board by adding 2 to 6% of the melamine content in the manufacture of the adhesive, but after the condensation reaction, the amount of added elements is excessive There is a problem of significantly lower physical properties.

In addition, the Republic of Korea Patent No. 10-0552548 was able to produce a low formaldehyde medium density fiberboard, but the manufacturing process of the adhesive for producing the medium density fiberboard is complicated, the addition amount of the curing accelerator is high, and after the aging period even after the production of the adhesive There is a disadvantage that the manufacturing time is long.

Recently, problems associated with human hazards of formaldehyde have been highlighted, so manufacturing and using eco-friendly wood board products having lowered formaldehyde emissions are indispensable. Accordingly, the present inventors limit the molar ratio of initial formaldehyde / urea to a specific range when condensing formaldehyde with melamine and urea in order to lower the amount of formaldehyde emission, and add a specific amount of melamine to the final adhesive. The purpose of the present invention is to provide a method for producing a melamine-urea-formaldehyde resin adhesive that can reduce the cost of adhesive manufacturing by controlling the molar ratio of the polymer, simplify the adhesive synthesis process, and minimize the amount of formaldehyde released after the production of the medium density fiber board. have.

In another aspect, the present invention is to provide a method for producing a medium density fiber board using the melamine-urea-formaldehyde resin adhesive.

The present invention 1) by adding an alkaline catalyst to formaldehyde to adjust the pH to 9.0 ± 0.2 and the reaction temperature to 75 ± 5 ℃ and then add the calculated amount of melamine and then increase the reaction temperature to 90 ± 2 ℃ To maintain for 30 ± 5 minutes; 2) After the step 1), add the primary urea to adjust the molar ratio of formaldehyde / urea to 1.50∼1.64, perform condensation reaction while maintaining the reaction temperature at 90 ± 2 ℃, and then add the secondary urea to formaldehyde / Adjusting the molar ratio of urea to 1.05 to 1.15 to capture unreacted formaldehyde; 3) after the step 2) of the melamine-urea-formaldehyde resin adhesive for medium-density fiberboard comprising the step of cooling the reaction to 75 ± 5 ℃ and then adding an alkali catalyst or an acid catalyst to maintain the pH to 8.5 ± 0.2 The manufacturing method is shown.

The melamine-urea-formaldehyde resin adhesive prepared according to the present invention not only reduces the adhesive manufacturing cost by simplifying the synthesis process of the adhesive but also reduces the formaldehyde without deteriorating the physical properties of the medium-density fiber board manufactured by using the adhesive or the adhesive. It can be used to produce low density medium density fiberboard.

This invention shows the manufacturing method of the melamine-urea-formaldehyde resin adhesive for manufacturing medium density fiber boards.

The present invention is 1) by adding an alkaline catalyst to formaldehyde to adjust the pH to 9.0 ± 0.2 and the reaction temperature to 75 ± 5 ℃ after adding 120 to 198 parts of melamine and then increase the reaction temperature to 90 ± 2 ℃ To maintain for 30 ± 5 minutes;

2) After the step 1), add the primary urea to adjust the molar ratio of formaldehyde / urea to 1.50∼1.64, perform condensation reaction while maintaining the reaction temperature at 90 ± 2 ℃, and then add the secondary urea to formaldehyde / Adjusting the molar ratio of urea to 1.05 to 1.15 to capture unreacted formaldehyde;

3) after the step 2) of the melamine-urea-formaldehyde resin adhesive for producing a medium density fiber board comprising the step of maintaining the pH to 8.5 ± 0.2 by adding an alkali catalyst or an acid catalyst after cooling to 75 ± 5 ℃ The manufacturing method is shown.

In the steps 1) and 3), the alkali catalyst may be any one selected from sodium hydroxide (NaOH) and potassium hydroxide (KOH).

The acid catalyst in step 3) may be any one selected from formic acid (HCOOH), hydrochloric acid (HCl).

In step 1), by controlling the pH of the initial reaction to 9.0 ± 0.2 and maintaining the reaction time for 30 ± 5 minutes, the condensation reaction of melamine can be inhibited and the reaction can proceed only to the methylolation step.

After the step 1), by adding the primary urea to adjust the molar ratio of formaldehyde / urea to 1.50 to 1.64 to promote methylolation of the urea to induce effective condensation of melamine and urea, by adding a secondary urea form Unreacted formaldehyde can be collected by adjusting the mole ratio of aldehyde / urea to 1.05 to 1.15.

By maintaining the pH of the product after the step 3) to 8.5 ± 0.2 can prevent the self-condensation of the product.

In the preparation of the melamine-urea-formaldehyde resin adhesive for producing a medium density fiber board of the present invention, various pH, reaction temperature, reaction time, content, etc. were investigated. In order to achieve the object of the present invention, It is desirable to provide a method for producing a melamine-urea-formaldehyde resin adhesive for producing a density fiber board.

The present invention includes a method for producing a medium degree fiber board using the melamine-urea-formaldehyde resin adhesive prepared above.

The present invention provides a medium density comprising the step of applying 10 to 20% by weight of the melamine-urea-formaldehyde resin adhesive prepared above and 1 to 5% by weight of the curing agent to 100 parts by weight of wood fiber The manufacturing method of a fiber board is shown.

The present invention provides a method for producing a medium density fiber board comprising the step of applying 15% by weight of the melamine-urea-formaldehyde resin adhesive prepared above and 3% by weight of a curing agent to 100 parts by weight of wood fibers. Indicates.

In the above, the curing agent may selectively use a curing agent known in the art, and for example, ammonium chloride may be used.

The method for producing a medium density fiber board of the present invention is carried out by various components, contents and conditions. In order to achieve the object of the present invention, it is preferable to provide a method for producing a medium density fiber board under the above-mentioned conditions. .

Hereinafter, the present invention will be described in detail with reference to Examples and Test Examples. However, these are intended to explain the present invention in more detail, and the scope of the present invention is not limited thereto.

Example 1 Preparation of Melamine-Added Low Molar Ratio Urea-Formaldehyde Resin

 4 parts by weight of sodium hydroxide, a 650 parts by weight alkaline solution of 37% formalin, was added to the reactor while stirring to adjust the pH to 9.0 ± 0.2 and the reaction temperature was maintained at 75 ± 5 ° C.

While maintaining the same pH range as described above, by adding 125 parts by weight or 198 parts by weight of melamine, the reaction temperature was raised to 90 ± 2 ℃ was maintained for 30 ± 5 minutes.

324 parts by weight of primary urea were added to control the molar ratio of formaldehyde / urea to 1.50 and condensed for 20 minutes while maintaining the reaction temperature at 90 ± 2 ° C.

Add 139 parts by weight of secondary urea to adjust the molar ratio of formaldehyde / urea to 1.05 and hold for 15 ± 5 minutes to collect unreacted formaldehyde, and cool the reaction to 75 ± 5 ° C. to add formic acid or hydrochloric acid. To prepare a melamine-added low molar ratio urea-formaldehyde resin adhesive by the step of maintaining the pH at 8.5 ± 0.2, and the measurement results of the physical properties of the adhesive are shown in Table 1 below.

Example 2 Preparation of Melamine-Added Low Molar Ratio Urea-Formaldehyde Resin

 4 parts by weight of sodium hydroxide, a 650 parts by weight alkaline solution of 37% formalin, was added to the reactor while stirring to adjust the pH to 9.0 ± 0.2 and the reaction temperature was maintained at 75 ± 5 ° C.

While maintaining the same pH range as described above, by adding 122 parts by weight or 194 parts by weight of melamine, the reaction temperature was raised to 90 ± 2 ℃ was maintained for 30 ± 5 minutes.

309 parts by weight of primary urea was added to control the molar ratio of formaldehyde / urea to 1.57 and condensed for 20 minutes while maintaining the reaction temperature at 90 ± 2 ° C.

Add 132 parts by weight of secondary urea to adjust the molar ratio of formaldehyde / urea to 1.10 and hold for 15 ± 5 minutes to collect unreacted formaldehyde, and cool the reaction to 75 ± 5 ° C to add formic acid or hydrochloric acid To prepare a melamine-added low molar ratio urea-formaldehyde resin adhesive by the step of maintaining the pH at 8.5 ± 0.2, and the measurement results of the physical properties of the adhesive are shown in Table 1 below.

Example 3 Preparation of Melamine-Added Low Molar Ratio Urea-Formaldehyde Resin

 4 parts by weight of sodium hydroxide, a 650 parts by weight alkaline solution of 37% formalin, was added to the reactor while stirring to adjust the pH to 9.0 ± 0.2 and the reaction temperature was maintained at 75 ± 5 ° C.

While maintaining the same pH range as described above, by adding 120 parts by weight or 191 parts by weight of melamine, the reaction temperature was raised to 90 ± 2 ℃ was maintained for 30 ± 5 minutes.

295 parts by weight of primary urea were added to control the molar ratio of formaldehyde / urea to 1.64 and condensed for 20 minutes while maintaining the reaction temperature at 90 ± 2 ° C.

Add 127 parts by weight of secondary urea to adjust the molar ratio of formaldehyde / urea to 1.15 and hold for 15 ± 5 minutes to collect unreacted formaldehyde, and cool the reaction to 75 ± 5 ° C. to add formic acid or hydrochloric acid. To prepare a melamine-added low molar ratio urea-formaldehyde resin adhesive by the step of maintaining the pH at 8.5 ± 0.2, and the measurement results of the physical properties of the adhesive are shown in Table 1 below.

Table 1. Physical Properties of Low Molar Ratio Urea-Formaldehyde Resin Added with Melamine

division Solid content
(%) Free formaldehyde
(%) Gel time
(sec) Item Melamine addition amount
(Parts by weight) Example 1
125 57.6 0.63 287 198 58.2 0.32 242 Example 2
122 55.5 0.77 249 194 57.5 0.50 209 Example 3
120 54.7 0.74 149 191 52.8 0.54 182 Comparative example
250 57.1 0.30 348 200 58.7 0.15 240

* Comparative Example: Marking two kinds of adhesives that are used commercially

As shown in Table 1, the amount of free formaldehyde and gelation time in the Examples according to the present invention were slightly different from those of the Comparative Example, but the melamine content of the product used as the Comparative Example was compared with the amount of the adhesive prepared in the present invention. There was a big difference, so the direct comparison was not meaningful.

<Example 4>

After applying 15 parts by weight of the melamine-added low molar ratio urea-formaldehyde resin adhesive prepared in Example 1 and 3 parts by weight of a curing agent based on 100 parts by weight of wood fiber, the medium density fiberboard was 6 mm thick at a target density of 700 kg / m 3. It was prepared by hot pressing at 170 ° C. for 240 seconds.

Table 2 shows the measured physical properties of the medium density fiberboard prepared with the melamine-added low molar ratio urea-formaldehyde resin adhesive prepared according to the synthesis method of the present invention.

Example 5

After applying 15 parts by weight of the melamine-added low molar ratio urea-formaldehyde resin adhesive prepared in Example 2 and 3 parts by weight of a curing agent based on 100 parts by weight of wood fibers, the medium density fiberboard was heated to a thickness of 6 mm at a target density of 700 kg / m 3. It was prepared by hot pressing at a temperature of 170 ° C. for 240 seconds.

Table 2 shows the measured physical properties of the medium density fiberboard prepared with the melamine-added low molar ratio urea-formaldehyde resin adhesive prepared according to the synthesis method of the present invention.

<Example 6>

After applying 15 parts by weight of the melamine-added low molar ratio urea-formaldehyde resin adhesive prepared in Example 3 and 3 parts by weight of a curing agent based on 100 parts by weight of wood fibers, the medium density fiberboard was heated to a thickness of 6 mm at a target density of 700 kg / m 3. It was prepared by thermal pressure at 170 ℃ for 240 seconds.

Table 2 shows the measured physical properties of the medium density fiberboard prepared with the melamine-added low molar ratio urea-formaldehyde resin adhesive prepared according to the synthesis method of the present invention.

Table 2. Properties of Medium Density Fiberboards Prepared with Melamine-Added Low Molar Ratio Urea-Formaldehyde Resin Adhesives

Item Density ¹⁾
(g / ㎥) Flexural strength ²⁾
(N / mm2) Peel Strength ³⁾
(N / mm2) Formaldehyde
Emission amount ⁴⁾
(Mg / L) Example 4
0.705 44.0 0.76 0.17 0.704 35.2 0.63 0.10 Example 5
0.703 40.4 0.85 0.27 0.704 35.7 0.90 0.22 Example 6
0.703 39.2 0.63 0.22 0.705 42.6 0.78 0.23 Comparative example
0.704 47.9 1.05 0.40 0.702 28.6 0.65 0.51

^{1), 2), 3), 4)} : Measured according to KS F 3200

* Comparative Example: Marking two kinds of adhesives that are used commercially

As shown in Table 2, the physical properties of the medium density fiber boards prepared in Examples 4 to 6 were not deteriorated compared to the medium density fiber boards prepared with the adhesives used as the comparative examples, and the physical properties such as density, bending strength, peel strength, etc. The amount of formaldehyde released showed a Super E ₀ grade of 0.3 mg / L or less in the case of the medium density fiberboard manufactured using the adhesive prepared in the present invention, thereby lowering the amount of formaldehyde released. The formaldehyde emission of the medium density fiberboard prepared with the adhesive used as the comparative example was higher than 0.4 mg / L despite the higher melamine content than the adhesives prepared in the present invention.

 Therefore, in the case of the melamine-added low molar ratio urea-formaldehyde resin adhesive prepared in the present invention, similar physical properties are maintained compared to conventional adhesives, and when the medium density fiberboard is manufactured using the same, the release rate of formaldehyde is maintained while maintaining peel strength and bending strength. The result which has the effect of reducing was obtained.

As described above, although described with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and modified within the scope of the present invention without departing from the spirit and scope of the invention described in the claims below. It will be appreciated that it can be changed.

Claims (3)

1) Add an alkaline catalyst to 650 parts by weight of formaldehyde to adjust the pH to 9.0 ± 0.2, adjust the reaction temperature to 75 ± 5 ° C, add 120-198 parts of melamine, and then set the reaction temperature to 90 ± 2 ° C. Raise to hold for 30 ± 5 minutes; 2) After the step 1), add the primary urea to adjust the molar ratio of formaldehyde / urea to 1.50∼1.64, perform condensation reaction while maintaining the reaction temperature at 90 ± 2 ℃, and then add the secondary urea to formaldehyde / Adjusting the molar ratio of urea to 1.05 to 1.15 to capture unreacted formaldehyde; 3) Method of producing a melamine-urea-formaldehyde resin adhesive for producing a medium-density fiber board comprising the step of cooling the reaction to 75 ± 5 ℃ after step 2) and then to maintain the pH to 8.5 ± 0.2 by adding an acid catalyst. The alkaline catalyst of step 1) is any one selected from sodium hydroxide (NaOH) and potassium hydroxide (KOH), and the acid catalyst of step 3) is any one selected from formic acid (HCOOH) and hydrochloric acid (HCl). Method for preparing melamine-urea-formaldehyde resin adhesive for producing medium density fiberboard. In the manufacturing method of the medium density fiberboard, 10 to 20 parts by weight of the melamine-urea-formaldehyde resin adhesive prepared by the method of claim 1 or 1 to 5 parts by weight of the hardwood fiber, characterized in that it comprises the step of applying Method for producing density fiberboard.