Low-cost high-water-resistance urea-formaldehyde resin and preparation method thereof

Abstract

The invention discloses low-cost high-water-resistance urea-formaldehyde resin and a preparation method thereof, and belongs to the technical field of urea-formaldehyde resin preparation. The urea-formaldehyde resin comprises the following components in parts by weight: 40-55 parts of formaldehyde, 15-25 parts of urea, 2-5 parts of melamine, 2-5 parts of acetone, 2-10 parts of ammonia water, 5-10 parts of butylbenzene and 20-40 parts of deionized water. The urea-formaldehyde resin is modified through acetone and butylbenzene, the content of free formaldehyde in the prepared urea-formaldehyde resin is low, the requirement of E0-grade environment-friendly urea-formaldehyde resin is met, and the urea-formaldehyde resin is resistant to boiling water and low in cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of urea - formaldehyde resin preparation, and particularly relates to a low - cost and high - water - resistant urea - formaldehyde resin and a preparation method thereof. Background Art

[0002] Urea - formaldehyde resin is widely used in wood adhesives due to its high bonding strength, simple process and low cost. It is the most widely used wood adhesive among the three aldehyde - based adhesives. However, its poor water resistance, insufficient stability, especially the problem of free formaldehyde release, seriously endanger the health of workers and limit its application.

[0003] In the prior art, by controlling the molar ratio of formaldehyde to urea to be 1.03 - 1.09, the addition amount of melamine to be 0.5 - 2% of urea, and adding urea in three times, the free formaldehyde content of the prepared urea - formaldehyde resin is less than 0.1%, reaching the E0 standard. However, in the high - molar - ratio (formaldehyde / (urea + melamine)=1.5) co - condensation resin, the addition amount of melamine has a very obvious influence on the formaldehyde release amount of the bonded product, but has little obvious improvement on water resistance, and melamine is expensive, resulting in a high production cost. Summary of the Invention

[0004] In order to overcome the above - mentioned technical problems existing in the prior art, the present invention provides a low - cost and high - water - resistant urea - formaldehyde resin and a preparation method thereof.

[0005] To achieve the above object, the technical scheme adopted by the present invention is as follows:

[0006] On the one hand, the present invention provides a low - cost and high - water - resistant urea - formaldehyde resin, comprising the following components in parts by weight:

[0007] 40 - 55 parts of formaldehyde, 15 - 25 parts of urea, 2 - 5 parts of melamine, 2 - 5 parts of acetone, 2 - 10 parts of ammonia water, 5 - 10 parts of styrene - butadiene, 20 - 40 parts of deionized water.

[0008] On the other hand, the present invention provides a preparation method of a low - cost and high - water - resistant urea - formaldehyde resin, specifically comprising the following steps:

[0009] (1) Add formaldehyde into a container, add an alkaline pH regulator to adjust the pH to 7.5 - 10, start stirring, then add melamine, heat up to 40 - 55 °C, and then add acetone for reaction;

[0010] (2) Add part of urea and part of deionized water, add an alkaline pH regulator to adjust the pH to 7 - 10, and heat up for reaction;

[0011] (3) Add the remaining part of urea, part of ammonia water and the remaining amount of water for heat - preservation reaction;

[0012] (4) Add an acidic pH regulator to adjust the pH to 4 - 6. After reacting until the viscosity reaches 160 - 200 mPa·s, add a basic pH regulator to quickly adjust the pH to 7 - 10;

[0013] (5) Add the remaining urea and the remaining ammonia water, react for a period of time under the condition of pH 7 - 10, cool down, and mix evenly with styrene - butadiene copolymer to obtain the low - cost and high - water - resistant urea - formaldehyde resin.

[0014] As a further scheme of the present invention: In step (1), the reaction time is 0.5 - 1 h.

[0015] As a further scheme of the present invention: In step (2), the addition amount of the urea is 50 - 80% of the total amount of the urea;

[0016] and / or, the addition amount of the deionized water is 40 - 60% of the total amount of the deionized water.

[0017] As a further scheme of the present invention: In step (2), the reaction conditions are: temperature 80 - 90 °C, reaction time 0.5 - 1 h.

[0018] As a further scheme of the present invention: In step (3), the addition amount of the urea is 10 - 20% of the total amount of the urea;

[0019] and / or, the addition amount of the ammonia water is 40 - 60% of the total amount of the ammonia water.

[0020] As a further scheme of the present invention: In step (3), the reaction conditions are: temperature 80 - 90 °C, reaction time 0.5 - 2 h.

[0021] As a further scheme of the present invention: In step (5), the reaction conditions are: temperature 70 - 80 °C, reaction time 1 - 2 h.

[0022] As a further scheme of the present invention: The basic pH regulator includes at least one of sodium hydroxide, potassium hydroxide, triethanolamine, ammonia water, sodium carbonate, potassium carbonate, barium hydroxide or their aqueous solutions;

[0023] and / or, the acidic pH regulator includes at least one of formic acid, acetic acid, sulfonic acid, hydrochloric acid, sulfuric acid or their aqueous solutions.

[0024] The beneficial effects of the present invention are as follows:

[0025] 1. The present invention modifies the urea - formaldehyde resin with acetone and styrene - butadiene copolymer. Through the synthesis process, while ensuring the performance, the cost of the urea - formaldehyde resin is effectively controlled.

[0026] 2. The content of free formaldehyde in the modified urea-formaldehyde resin prepared by the present invention is significantly reduced, which improves the working environment, reduces the physical damage to people, and fully meets the indicators of the environmentally friendly urea-formaldehyde resin with low formaldehyde and low toxicity.

[0027] 3. The method of the present invention uses acetone, triamine, and styrene-butadiene, making it easy to form a network structure during resin curing, and keeping the bonding strength, water resistance, and free aldehyde of the resin at a very high level. Detailed implementation mode

[0028] The present invention will be further described below by way of examples, but the present invention is not limited to the scope of the described examples. The experimental methods without specific conditions in the following examples are carried out according to conventional methods and conditions, or selected according to the product specifications. In addition, the reagents and raw materials used in the present invention are all commercially available.

[0029] Example 1

[0030] A low-cost and high-water-resistant urea-formaldehyde resin, the preparation raw materials of which include: 202 g of formaldehyde, 60 g of urea, 20 g of melamine, 20 g of acetone, 40 g of ammonia water, 40 g of styrene-butadiene, and 150 g of deionized water.

[0031] A preparation method of a low-cost and high-water-resistant urea-formaldehyde resin specifically includes the following steps:

[0032] (1) Add 202 g of formaldehyde to a three-necked flask, add 10% sodium hydroxide aqueous solution to adjust the pH to 7.5, start stirring, add 20 g of melamine, heat up to 45 °C, add 20 g of acetone, and keep warm for 0.5 h;

[0033] (2) Add 40 g of urea and 75 g of deionized water, add 10% sodium hydroxide aqueous solution to adjust the pH to 7.5, heat up to 80 °C, and keep warm and reflux for 1 h;

[0034] (3) Add 10 g of urea, 20 g of ammonia water, and 75 g of deionized water, and keep warm and react at 80 °C for 0.5 h;

[0035] (4) Add 10% hydrochloric acid aqueous solution to adjust the pH to 4.5, react until the viscosity is 160 mPa·s, and add 10% sodium hydroxide aqueous solution to quickly raise the pH to 7.5;

[0036] (5) Add 10 g of urea and 20 g of ammonia water, react at pH 7.5 and temperature 75 °C for 1 h, cool to room temperature, add 40 g of styrene-butadiene, mix well and discharge to obtain a low-cost and high-water-resistant urea-formaldehyde resin.

[0037] Example 2

[0038] A low-cost and highly water-resistant urea-formaldehyde resin, the raw materials for its preparation include: 185 g of formaldehyde, 100 g of urea, 15 g of melamine, 15 g of acetone, 30 g of ammonia water, 30 g of styrene-butadiene, and 100 g of deionized water.

[0039] A method for preparing a low-cost and highly water-resistant urea-formaldehyde resin, specifically including the following steps:

[0040] (1) Add 185 g of formaldehyde to a three-necked flask, add 10% sodium hydroxide aqueous solution to adjust the pH to 8, start stirring, add 15 g of melamine, heat up to 50 °C, add 15 g of acetone, and keep warm for 1 h;

[0041] (2) Add 60 g of urea and 50 g of deionized water, add 10% sodium hydroxide aqueous solution to adjust the pH to 8, heat up to 90 °C, and keep warm and reflux for 1 h;

[0042] (3) Add 20 g of urea, 15 g of ammonia water, 50 g of deionized water, and keep warm and react at 90 °C for 0.5 h;

[0043] (4) Add 10% hydrochloric acid aqueous solution to adjust the pH to 5, react until the viscosity reaches 180 mPa·s, and add 10% sodium hydroxide aqueous solution to quickly raise the pH to 8;

[0044] (5) Add 20 g of urea and 15 g of ammonia water, react at pH 8 and temperature 80 °C for 1 h, cool to room temperature, add 30 g of styrene-butadiene, mix well and discharge to obtain a low-cost and highly water-resistant urea-formaldehyde resin.

[0045] Example 3

[0046] A low-cost and highly water-resistant urea-formaldehyde resin, the raw materials for its preparation include: 162 g of formaldehyde, 80 g of urea, 10 g of melamine, 10 g of acetone, 10 g of ammonia water, 20 g of styrene-butadiene, and 100 g of deionized water.

[0047] The method for preparing the low-cost and highly water-resistant urea-formaldehyde resin specifically includes the following steps:

[0048] (1) Add 162 g of formaldehyde to a three-necked flask, add 10% sodium hydroxide aqueous solution to adjust the pH to 8.5, start stirring, add 10 g of melamine, heat up to 50 °C, add 10 g of acetone, and keep warm for 0.5 h;

[0049] (2) Add 60 g of urea and 50 g of deionized water, add 10% sodium hydroxide aqueous solution to adjust the pH to 8.5, heat up to 85 °C, and keep warm and reflux for 1 h;

[0050] (3) Add 10 g of urea, 5 g of ammonia water, 50 g of deionized water, and keep warm and react at 85 °C for 0.5 h;

[0051] (4) Add 10% hydrochloric acid aqueous solution to adjust the pH to 5.5, react until the viscosity reaches 200 mPa·s, and then add 10% sodium hydroxide aqueous solution to quickly raise the pH to 8;

[0052] (5) Add 10 g of urea and 5 g of ammonia water, react at pH 8 and a temperature of 80 °C for 1 h, cool to room temperature, add 20 g of styrene-butadiene, mix well and discharge to obtain a low-cost and high-water-resistant urea-formaldehyde resin.

[0053] Comparative Example 1

[0054] A urea-formaldehyde resin, the raw materials for its preparation include: 202 g of formaldehyde, 60 g of urea, and 150 g of deionized water.

[0055] The preparation method of the above urea-formaldehyde resin specifically includes the following steps:

[0056] (1) Add 202 g of formaldehyde to a three-necked flask, add 10% sodium hydroxide aqueous solution to adjust the pH to 8, start stirring, and heat up to 45 °C;

[0057] (2) Add 40 g of urea and 75 g of deionized water, add 10% sodium hydroxide aqueous solution to adjust the pH to 8.5, heat up to 80 °C, and keep the temperature for reflux for 1 h;

[0058] (3) Add 20 g of urea and 75 g of deionized water, and react at 80 °C for 0.5 h;

[0059] (4) Add 10% hydrochloric acid aqueous solution to adjust the pH to 4.5, react until the viscosity reaches 160 mPa·s, add 10% sodium hydroxide aqueous solution to quickly raise the pH to 7.5, then react at a temperature of 75 °C for 1 h, cool to room temperature, and discharge to obtain urea-formaldehyde resin.

[0060] Comparative Example 2

[0061] A urea-formaldehyde resin, the raw materials for its preparation include: 185 g of formaldehyde, 100 g of urea, and 15 g of melamine.

[0062] The above urea-formaldehyde resin and its preparation method specifically include the following steps:

[0063] (1) Add 185 g of formaldehyde to a three-necked flask, add 10% sodium hydroxide aqueous solution to adjust the pH to 8.5, start stirring, add 15 g of melamine, heat up to 50 °C, and keep the temperature for 1 h;

[0064] (2) Add 60 g of urea, add 10% sodium hydroxide aqueous solution to adjust the pH to 9, heat up to 90 °C, and keep the temperature for reflux for 1 h;

[0065] (3) Add 20 g of urea, and react at 90 °C for 0.5 h;

[0066] (4) adding 10% hydrochloric acid aqueous solution to adjust the pH to 5, reacting until the viscosity reaches 180 mPa.s, and then adding 10% sodium hydroxide aqueous solution to quickly raise the pH to 8;

[0067] (5) Add 20 g of urea, adjust the pH to 8, react at 80° C. for 1 h, cool to room temperature, discharge the mixture, and obtain urea-formaldehyde resin.

[0068] Comparative Example 3

[0069] A urea-formaldehyde resin is prepared from raw materials comprising: 162 g of formaldehyde, 80 g of urea, 10 g of melamine and 100 g of deionized water.

[0070] A method for preparing urea-formaldehyde resin comprises the following steps:

[0071] (1) Add 162 g of formaldehyde into a three-necked flask, add 10% sodium hydroxide aqueous solution to adjust the pH to 9, start stirring, add 10 g of melamine, raise the temperature to 50° C., and keep warm for 0.5 h;

[0072] (2) Add 60 g of urea and 50 g of deionized water, add 10% sodium hydroxide aqueous solution to adjust the pH to 10, raise the temperature to 85° C., and keep reflux for 1 hour;

[0073] (3) Add 10 g urea and 50 g deionized water, and heat at 85 °C for 0.5 h;

[0074] (4) adding 10% hydrochloric acid aqueous solution to adjust the pH to 5, reacting until the viscosity reaches 200 mPa.s, and adding 10% sodium hydroxide aqueous solution to quickly raise the pH to 8;

[0075] (5) Add 10 g of urea, adjust the pH to 8, react at 80° C. for 1 h, cool, and discharge to obtain urea-formaldehyde resin.

[0076] Comparative Example 4

[0077] The only difference from Example 1 is that butadiene is not added.

[0078] Comparative Example 5

[0079] The only difference from Example 1 is that no acetone was added.

[0080] Comparative Example 6

[0081] The only difference from Example 1 is that acetone is added after the pH is adjusted to 4.5 in step (4).

[0082] Comparative Example 7

[0083] The only difference from Example 1 is that ammonia water is added all at once in step (3).

[0084] Effect Examples

[0085] Adopt the national standard GB / T 14732-2017 "Urea-formaldehyde, phenol-formaldehyde, and melamine-formaldehyde resins for wood industry adhesives": Determine the various indicators of urea-formaldehyde resin. The specific test results are shown in Table 1. Among them, the bonding strength is the average strength of 8 samples.

[0086] Table 1 Test Results of Urea-Formaldehyde Resin Indicators

[0087]

[0088] As can be seen from Table 1, compared with the comparative example, in the examples of the present invention, the free formaldehyde and formaldehyde release amount are greatly reduced, which improves the working environment and reduces the physical damage to workers, and is very beneficial to the environment. At the same time, the water resistance has been considerably improved. The improvement of water resistance expands the application range of urea-formaldehyde resin. In addition, the cost of the urea-formaldehyde resin prepared according to the method of the present invention is not much different from that in the market, and the improvement of the cost can also be accepted by the market.

[0089] Finally, it should also be noted that in the present invention, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device.

[0090] Although the present disclosure has been disclosed above through the description of specific embodiments of the present disclosure, it should be understood that those skilled in the art can design various modifications, improvements or equivalents to the present disclosure within the spirit and scope of the appended claims. These modifications, improvements or equivalents should also be considered to be included within the scope claimed by the present disclosure.

Claims

1. A low-cost and highly water-resistant urea-formaldehyde resin, characterized in that, It comprises components in the following parts by weight: 40 - 55 parts of formaldehyde, 15 - 25 parts of urea, 2 - 5 parts of melamine, 2 - 5 parts of acetone, 2 - 10 parts of ammonia water, 5 - 10 parts of styrene - butadiene, and 20 - 40 parts of deionized water.

2. The preparation method of the low-cost and highly water-resistant urea-formaldehyde resin according to claim 1, wherein, Specifically, it includes the following steps: (1) Add formaldehyde into a container, add an alkaline pH regulator to adjust the pH to 7.5 - 10, start stirring, then add melamine, heat up to 40 - 55 °C, and then add acetone for reaction; (2) Add part of the urea and part of the deionized water, add an alkaline pH regulator to adjust the pH to 7 - 10, and heat up for reaction; (3) Then add the remaining part of the urea, part of the ammonia water and the remaining water for heat - preservation reaction; (4) Add an acidic pH regulator to adjust the pH to 4 - 6, after the reaction until the viscosity reaches 160 - 200 mPa·s, then quickly add an alkaline pH regulator to adjust the pH to 7 - 10; (5) Add the remaining urea and the remaining ammonia water, react for a period of time under the condition of pH 7 - 10, cool down, and mix evenly with styrene - butadiene to obtain the low - cost and high - water - resistant urea - formaldehyde resin.

3. The preparation method of the low-cost and highly water-resistant urea-formaldehyde resin according to claim 2, wherein, In step (1), the reaction time is 0.5 - 1 h.

4. The preparation method of the low-cost and high-water-resistant urea-formaldehyde resin according to claim 2, characterized in that, In step (2), the addition amount of the urea is 50 - 80% of the total amount of the urea; and / or, the addition amount of the deionized water is 40 - 60% of the total amount of the deionized water.

5. The preparation method of the low-cost and high-water-resistant urea-formaldehyde resin according to claim 2, characterized in that, In step (2), the reaction conditions are: temperature 80 - 90 °C, reaction time 0.5 - 1 h.

6. The preparation method of the low-cost and high-water-resistant urea-formaldehyde resin according to claim 2, characterized in that, In step (3), the addition amount of the urea is 10 - 20% of the total amount of the urea; and / or, the addition amount of the ammonia water is 40 - 60% of the total amount of the ammonia water.

7. The preparation method of the low-cost and high water-resistant urea-formaldehyde resin according to claim 2, characterized in that, In step (3), the reaction conditions are: temperature 80 - 90 °C, reaction time 0.5 - 2 h.

8. The preparation method of the low-cost and highly water-resistant urea-formaldehyde resin according to claim 2, characterized in that, In step (5), the reaction conditions are: temperature 70 - 80 °C, reaction time 1 - 2 h.

9. The preparation method of the low-cost and highly water-resistant urea-formaldehyde resin according to claim 2, characterized in that, The alkaline pH regulator includes at least one of sodium hydroxide, potassium hydroxide, triethanolamine, ammonia water, sodium carbonate, potassium carbonate, barium hydroxide or their aqueous solutions; and / or, the acidic pH regulator includes at least one of formic acid, acetic acid, sulfonic acid, hydrochloric acid, sulfuric acid or their aqueous solutions.

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