Modified urea-formaldehyde resin adhesive for bamboo boards and preparation method of modified urea-formaldehyde resin adhesive

Abstract

The invention belongs to the technical field of adhesives, and particularly relates to a modified urea-formaldehyde resin adhesive for bamboo boards and a preparation method thereof, and the modified urea-formaldehyde resin adhesive comprises the following components in parts by weight: 500-600 parts of a formaldehyde solution, 180-270 parts of urea peroxide, 30-70 parts of melamine, 20-30 parts of a silicate solution, 25-15 parts of nano SiO2, 15-35 parts of ammonium chloride and 30-50 parts of an alkaline pH regulator. According to the modified urea-formaldehyde resin adhesive for the bamboo board, formaldehyde and urea peroxide serve as main raw materials to generate modified urea-formaldehyde resin, so that the bonding strength of the adhesive is improved, meanwhile, silicate and ammonium chloride are added, the silicate and ammonium chloride have the effects of an anti-sticking agent and a curing agent respectively, and can react with free formaldehyde, so that the bonding strength of the adhesive is improved, and the service life of the adhesive is prolonged. Therefore, the final formaldehyde emission of the adhesive is reduced.

Description

Technical Field

[0001] The present application belongs to the technical field of adhesives, and specifically relates to a modified urea-formaldehyde resin adhesive for bamboo boards and a preparation method thereof. Background Art

[0002] As a green, environmentally friendly and renewable building material, bamboo board has strong regeneration ability as its raw material, bamboo, and is a sustainable resource. The use of bamboo board can reduce dependence on forest resources and help protect the ecological environment.

[0003] Melamine formaldehyde resin is one of the most commonly used adhesives in the processing of bamboo boards because of its fast curing speed, good heat and wear resistance, water resistance and weather resistance, high hardness and high bonding strength. Existing melamine formaldehyde resin uses a large amount of formaldehyde in the raw materials. Although the formaldehyde emission will decrease after curing, there is still a problem of high formaldehyde emission during the production process and before it is completely cured.

[0004] Therefore, a new adhesive is needed to overcome the problem of high formaldehyde emission when melamine formaldehyde resin is used in bamboo boards. Summary of the invention

[0005] The problem that the present application aims to solve is to provide a modified urea-formaldehyde resin adhesive for bamboo boards and a preparation method thereof. The adhesive uses formaldehyde and urea peroxide as main raw materials to generate modified urea-formaldehyde resin, thereby improving the bonding strength of the adhesive. Silicate and ammonium chloride are added at the same time. The two not only act as anti-adhesives and curing agents respectively, but can also react with free formaldehyde, thereby reducing the final formaldehyde release of the adhesive.

[0006] In order to solve the above technical problems, this application adopts the following technical solutions:

[0007] On the one hand, the present application provides a modified urea-formaldehyde resin adhesive for bamboo board, comprising, by weight:

[0008]

[0009] Furthermore, the silicate solution includes one of a lithium silicate solution, a sodium silicate solution and a potassium silicate solution.

[0010] Furthermore, the alkaline pH regulator includes one of sodium carbonate and sodium bicarbonate.

[0011] Furthermore, the mass fraction of the formaldehyde solution is 37% to 50%.

[0012] Furthermore, the concentration of the silicate solution is 22% to 58%.

[0013] In another aspect, the present application provides a method for preparing the above-mentioned adhesive, comprising the following steps:

[0014] An alkaline pH regulator is added to the formaldehyde solution to adjust the pH to a reaction pH, and then a first portion of urea peroxide is added to perform a first reaction to obtain a first reaction product; the silicate solution is added to the first reaction product to perform a second reaction to obtain a second reaction product; the ammonium chloride is added to the second reaction product to perform a third reaction to obtain a third reaction product; the melamine, the nano-SiO2 and the second portion of urea peroxide are added to the third reaction product to perform a fourth reaction to obtain a fourth reaction product; and the third portion of urea peroxide is added to the fourth reaction product to perform a fifth reaction to obtain the modified urea-formaldehyde resin adhesive for bamboo board materials.

[0015] Furthermore, the mass ratio of the first portion of urea peroxide, the second portion of urea peroxide and the third portion of urea peroxide is (7-9):(2-4):(3-5).

[0016] Furthermore, the pH value of the reaction pH is 8 to 8.6.

[0017] Furthermore, the temperature of the first reaction is 20-25° C., and the time of the first reaction is 10-20 min;

[0018] The temperature of the second reaction is 70-80°C, and the time of the second reaction is 30-40 minutes;

[0019] The temperature of the third reaction is 80-90° C., and the time of the third reaction is 80-120 min;

[0020] The temperature of the fourth reaction is 90-100° C., and the time of the fourth reaction is 30-40 min;

[0021] The temperature of the fifth reaction is 80-90° C., and the time of the fifth reaction is 20-30 min.

[0022] Furthermore, the first reaction is completed under stirring, and the stirring speed is 200-220 r / min.

[0023] This application has the following beneficial effects:

[0024] 1. The modified urea-formaldehyde resin adhesive for bamboo board provided in the present application uses urea peroxide and formaldehyde solution to react to generate modified urea-formaldehyde resin, which can not only improve the bonding strength of the adhesive, but also reduce the content of free formaldehyde, increase the degree of subsequent curing reaction, and prolong the activity period of the adhesive;

[0025] 2. The modified urea-formaldehyde resin adhesive for bamboo board provided in the present application uses a silicate solution as an anti-adhesive during preparation, which can not only prevent the adhesive from prematurely bonding, but also improve the bonding force of the adhesive, and can utilize the adsorption effect of silicate on formaldehyde, thereby reducing the content of free formaldehyde;

[0026] 3. The modified urea-formaldehyde resin adhesive for bamboo board provided in the present application uses ammonium chloride as a curing agent during preparation, which not only has a good curing effect, but also can further reduce the content of free formaldehyde through the addition reaction of ammonium chloride and formaldehyde;

[0027] 4. The modified urea-formaldehyde resin adhesive for bamboo panels provided in the application utilizes urea peroxide, melamine, silicate solution and ammonium chloride to react with formaldehyde during the preparation process, which greatly reduces the content of free formaldehyde. At the same time, by adding nano-SiO2, the free formaldehyde can be further adsorbed, which can ensure that the adhesive can maintain a low formaldehyde release after long-term storage. DETAILED DESCRIPTION

[0028] The technical solutions in some embodiments of the present application are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments provided by the present application, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present application.

[0029] Example 1

[0030] The modified urea-formaldehyde resin adhesive for bamboo board was prepared as follows:

[0031] S1. Add 30 parts of sodium carbonate to 500 parts of a 50% formaldehyde solution, adjust the pH to 8, then add 105 parts of urea peroxide, stir at 200 r / min at 20°C, react for 20 minutes, and obtain a first reaction product;

[0032] S2. 20 parts by mass of 22% lithium silicate solution were added to the first reaction product, and the reaction was carried out at 70 ° C for 40 min to obtain a second reaction product;

[0033] S3. adding 15 parts of ammonium chloride to the second reaction product and reacting at 80 ° C for 120 min to obtain a third reaction product;

[0034] S4. 30 parts of melamine, 15 parts of nano-SiO2 and 30 parts of urea peroxide were added to the third reaction product and reacted at 90 ° C for 40 min to obtain a fourth reaction product;

[0035] S5. Add 45 parts of urea peroxide to the fourth reaction product, react at 80° C. for 30 min, and obtain the modified urea-formaldehyde resin adhesive for bamboo board.

[0036] Example 2

[0037] The modified urea-formaldehyde resin adhesive for bamboo board was prepared as follows:

[0038] S1. Add 40 parts of sodium carbonate to 550 parts of a 44% formaldehyde solution, adjust the pH to 8.3, then add 120 parts of urea peroxide, stir at 210 r / min at 23°C, react for 15 minutes, and obtain a first reaction product;

[0039] S2. adding 25 parts by mass of 40% sodium silicate solution to the first reaction product and reacting at 75 ° C for 35 min to obtain a second reaction product;

[0040] S3. adding 25 parts of ammonium chloride to the second reaction product and reacting at 85 ° C for 100 min to obtain a third reaction product;

[0041] S4. 50 parts of melamine, 10 parts of nano-SiO2 and 45 parts of urea peroxide were added to the third reaction product and reacted at 95 ° C for 35 min to obtain a fourth reaction product;

[0042] S5. Add 60 parts of urea peroxide to the fourth reaction product, react at 85° C. for 25 minutes, and obtain the modified urea-formaldehyde resin adhesive for bamboo board.

[0043] Example 3

[0044] The modified urea-formaldehyde resin adhesive for bamboo board was prepared as follows:

[0045] S1. Add 50 parts of sodium bicarbonate to 600 parts of a 22% formaldehyde solution, adjust the pH to 8.6, then add 135 parts of urea peroxide, stir at 220 r / min at 25°C, react for 10 minutes, and obtain a first reaction product;

[0046] S2. adding 30 parts by mass of 58% potassium silicate solution to the first reaction product and reacting at 80 ° C for 30 min to obtain a second reaction product;

[0047] S3. adding 35 parts of ammonium chloride to the second reaction product and reacting at 90 ° C for 80 min to obtain a third reaction product;

[0048] S4. 70 parts of melamine, 15 parts of nano-SiO2 and 60 parts of urea peroxide were added to the third reaction product and reacted at 100 ° C for 30 min to obtain a fourth reaction product;

[0049] S5. Add 75 parts of urea peroxide to the fourth reaction product, react at 90° C. for 20 minutes, and obtain the modified urea-formaldehyde resin adhesive for bamboo board.

[0050] Comparative Example 1

[0051] Follow these steps to prepare the urea-formaldehyde resin adhesive for bamboo panels:

[0052] S1. Add 30 parts of sodium carbonate to 500 parts of a 50% formaldehyde solution, adjust the pH to 8, then add 105 parts of urea, stir at 200 r / min at 20°C, react for 20 minutes, and obtain a first reaction product;

[0053] S2. 20 parts by mass of 22% lithium silicate solution were added to the first reaction product, and the reaction was carried out at 70 ° C for 40 min to obtain a second reaction product;

[0054] S3. adding 15 parts of ammonium chloride to the second reaction product and reacting at 80 ° C for 120 min to obtain a third reaction product;

[0055] S4. 30 parts of melamine, 15 parts of nano-SiO2 and 30 parts of urea were added to the third reaction product and reacted at 90 ° C for 40 min to obtain a fourth reaction product;

[0056] S5. Add 45 parts of urea to the fourth reaction product, react at 80° C. for 30 minutes, and obtain the urea-formaldehyde resin adhesive for bamboo board.

[0057] Comparative Example 2

[0058] Follow these steps to prepare the urea-formaldehyde resin adhesive for bamboo panels:

[0059] S1. Add 30 parts of sodium carbonate to 500 parts of a 50% formaldehyde solution, adjust the pH to 8, then add 105 parts of urea peroxide, stir at 200 r / min at 20°C, react for 20 minutes, and obtain a first reaction product;

[0060] S2. adding 20 parts of talc to the first reaction product and reacting at 70 ° C for 40 min to obtain a second reaction product;

[0061] S3. adding 15 parts of ammonium chloride to the second reaction product and reacting at 80 ° C for 120 min to obtain a third reaction product;

[0062] S4. 30 parts of melamine, 15 parts of nano-SiO2 and 30 parts of urea peroxide were added to the third reaction product and reacted at 90 ° C for 40 min to obtain a fourth reaction product;

[0063] S5. Add 45 parts of urea peroxide to the fourth reaction product, react at 80° C. for 30 min, and obtain the urea-formaldehyde resin adhesive for bamboo board.

[0064] Comparative Example 3

[0065] Follow these steps to prepare the urea-formaldehyde resin adhesive for bamboo panels:

[0066] S1. Add 30 parts of sodium carbonate to 500 parts of a 50% formaldehyde solution, adjust the pH to 8, then add 105 parts of urea peroxide, stir at 200 r / min at 20°C, react for 20 minutes, and obtain a first reaction product;

[0067] S2. 20 parts by mass of 22% lithium silicate solution were added to the first reaction product, and the reaction was carried out at 70 ° C for 40 min to obtain a second reaction product;

[0068] S3. adding 15 parts of zinc chloride to the second reaction product and reacting at 80 ° C for 120 min to obtain a third reaction product;

[0069] S4. 30 parts of melamine, 15 parts of nano-SiO2 and 30 parts of urea peroxide were added to the third reaction product and reacted at 90 ° C for 40 min to obtain a fourth reaction product;

[0070] S5. Add 45 parts of urea peroxide to the fourth reaction product, react at 80° C. for 30 min, and obtain the urea-formaldehyde resin adhesive for bamboo board.

[0071] Experimental Example 1

[0072] The urea-formaldehyde resin adhesives prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were used to press 6 groups of bamboo boards, with 3 bamboo boards pressed in each group. The bonding strength, internal bonding strength, immersion peeling strength, water content and formaldehyde emission of the bamboo boards were measured according to GB / T17657-2013 "Test methods for physical and chemical properties of artificial boards and veneer artificial boards", and the test results were averaged. The test results are shown in Table 1.

[0073] Table 1

[0074]

[0075] It can be seen from the above table that the modified urea-formaldehyde resin adhesive for bamboo boards provided in the present application greatly improves the bonding strength of the adhesive through urea peroxide, and under the action of urea peroxide, melamine, silicate solution, ammonium chloride and nano-SiO2, the content of free formaldehyde is greatly reduced. The adhesive provided in the present application not only has excellent bonding performance, but also has extremely low formaldehyde emission, and is a very green and environmentally friendly excellent board adhesive.

[0076] The above is only a preferred embodiment of the present application. It should be understood that the present application is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge in the relevant field. The changes and modifications made by those skilled in the art shall not deviate from the spirit and scope of the present application, and shall be within the scope of protection of the claims attached to the present application.

Claims

1. A modified urea-formaldehyde resin adhesive for bamboo board, characterized in that: In parts by weight:

2. The adhesive according to claim 1, characterized in that The silicate solution includes one of a lithium silicate solution, a sodium silicate solution and a potassium silicate solution.

3. The adhesive according to claim 1, characterized in that The alkaline pH adjuster includes one of sodium carbonate and sodium bicarbonate.

4. The adhesive according to claim 1, characterized in that The mass fraction of the formaldehyde solution is 37% to 50%.

5. The adhesive according to claim 1 or 2, characterized in that: The concentration of the silicate solution is 22% to 58%.

6. A method for preparing the adhesive according to any one of claims 1 to 5, characterized in that: The following steps are involved: adding an alkaline pH regulator to the formaldehyde solution to adjust the pH to a reaction pH, then adding a first portion of urea peroxide to perform a first reaction to obtain a first reaction product; adding the silicate solution to the first reaction product to carry out a second reaction to obtain a second reaction product; adding the ammonium chloride to the second reaction product to carry out a third reaction to obtain a third reaction product; adding the melamine, the nano-SiO2 and the second portion of urea peroxide to the third reaction product to carry out a fourth reaction to obtain a fourth reaction product; and The third portion of urea peroxide is added to the fourth reaction product to carry out a fifth reaction to obtain the modified urea-formaldehyde resin adhesive for bamboo board materials.

7. The method according to claim 6, characterized in that The mass ratio of the first portion of urea peroxide, the second portion of urea peroxide and the third portion of urea peroxide is (7-9):(2-4):(3-5).

8. The method according to claim 6, characterized in that The pH value of the reaction pH is 8 to 8.

6.

9. The method according to claim 6, characterized in that The temperature of the first reaction is 20-25° C., and the time of the first reaction is 10-20 min; The temperature of the second reaction is 70-80°C, and the time of the second reaction is 30-40 minutes; The temperature of the third reaction is 80-90° C., and the time of the third reaction is 80-120 min; The temperature of the fourth reaction is 90-100° C., and the time of the fourth reaction is 30-40 min; The temperature of the fifth reaction is 80-90° C., and the time of the fifth reaction is 20-30 min.

10. The method according to claim 9, characterized in that The first reaction is completed under stirring, and the stirring speed is 200-220 r / min.

Images