Preparation method of adhesive for manufacturing regenerated composite keel

Abstract

The invention relates to a preparation method of a binder for manufacturing a regenerated composite keel, which comprises the following steps: S1, adding a formaldehyde aqueous solution into a reaction kettle at room temperature, and then adding polyvinyl alcohol into the formaldehyde aqueous solution; s2, adding an industrial chemical formaldehyde catching agent and urea into the solution obtained in the step S1, heating the solution to 80 DEG C, stopping gas, preserving heat for 30 minutes, adjusting the pH value to 4.6 by using an acid solution, and continuing the reaction; the polyvinyl alcohol is used for modifying an original solution, ether bonds are generated in the reaction process to seal hydrophilic groups, the purpose of improving water resistance is achieved, meanwhile, the formaldehyde concentration in the solution is reduced, and the formaldehyde catching agent is matched for catching free formaldehyde molecules, so that the number of the free formaldehyde molecules carried by the binder after the binder is prepared is greatly reduced; therefore, the formaldehyde release amount after the adhesive is used for manufacturing the regenerated composite keel is greatly reduced, and the problem that the personnel health is affected due to the fact that the formaldehyde release amount of the adhesive is too large when the regenerated composite keel is used is solved.

Description

Technical Field

[0001] The invention relates to the field of adhesive production, in particular to a method for preparing an adhesive for making a regenerated composite keel. Background Art

[0002] Adhesives are widely used in the production of recycled composite keels due to their good bonding strength, ease of use, easy availability of raw materials and low cost. With the development of the wood-based panel industry and the furniture industry, companies are constantly putting forward higher requirements for adhesives and the final effects after their application.

[0003] The traditional adhesive is mainly urea-formaldehyde resin, which has a single preparation process and contains a large amount of free formaldehyde after preparation. After being used in the production of recycled composite keels, it will release a large amount of formaldehyde, which may affect the health of personnel. In addition, the production requires continuous conversion between high and low temperatures, the actual production energy consumption is large, and it is difficult to operate. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the prior art, provide a method for preparing an adhesive for making a regenerated composite keel, and solve the problem in the prior art that a large amount of formaldehyde is released after the traditional adhesive is used for making the regenerated composite keel, which affects the health of personnel.

[0005] To achieve the above object, the present invention provides a method for preparing a binder for making a regenerated composite keel, comprising the following steps:

[0006] S1. Adding formaldehyde aqueous solution into a reaction kettle at room temperature, and then adding polyvinyl alcohol into the formaldehyde aqueous solution;

[0007] S2, adding industrial chemical formaldehyde scavenger and urea to the solution obtained in step S1, and heating the solution to 80° C., then stopping the gas and keeping the temperature for 30 minutes, and then adjusting the pH to 4.6 with an acid solution to continue the reaction;

[0008] S3. When the solution obtained in step S2 is dispersed, an acid solution is used to adjust the pH to 5.4, and urea and melamine are added to continue the reaction;

[0009] S4, stopping the operation of the reactor, adding urea and light calcium carbonate to the solution obtained in step S3, reacting and naturally cooling at room temperature, and then extracting glue to obtain a binder.

[0010] By adopting this technical solution, polyvinyl alcohol is used to modify the original solution, and ether bonds are generated in the reaction process to block hydrophilic groups to achieve the purpose of improving water resistance. At the same time, the formaldehyde concentration in the solution is reduced, and the formaldehyde scavenger is used to capture free formaldehyde molecules, which greatly reduces the number of free formaldehyde molecules carried by the binder after preparation, thereby greatly reducing the amount of formaldehyde released after the binder is used to make regenerated composite keels, solving the problem of excessive formaldehyde release from the binder affecting the health of personnel when using regenerated composite keels; the entire binder production process only relies on the reactor being heated to 80°C and cooperating with the reactor's own insulation function to complete, without the need for high-temperature heating or repeated conversion of high and low temperatures, reducing the difficulty of production operations, while saving production energy consumption and greatly improving production efficiency.

[0011] Furthermore, step S1 comprises: dissolving formaldehyde in water to obtain a formaldehyde aqueous solution, wherein the mass ratio of formaldehyde to water is 6-7.

[0012] By adopting this technical solution, formaldehyde is diluted by preparing a formaldehyde aqueous solution, thereby reducing the amount of formaldehyde used.

[0013] Furthermore, the molar ratio of the formaldehyde to the total amount of urea added three times in steps S2 to S4 is 0.65.

[0014] By adopting this technical solution, the amount of urea added can be controlled.

[0015] Furthermore, in step S2, the mass ratio of the industrial chemical formaldehyde scavenger to urea is 0.4 to 0.6.

[0016] Furthermore, in step S2, the industrial chemical formaldehyde scavenger is a resorcinol solution.

[0017] By adopting this technical solution, a condensation reaction can be effectively carried out with free formaldehyde molecules to generate stable high molecular polymers, thereby reducing the amount of formaldehyde released.

[0018] Furthermore, in step S2, the heating rate of the solution is controlled to be 1°C / 1.5min.

[0019] By adopting this technical solution, the heating rate can be controlled and the reaction time can be extended to ensure that the normal reaction between the substances can be carried out at 80°C. At the same time, it can avoid the temperature increasing too quickly to affect the performance of the substances themselves and affect the production accuracy.

[0020] Furthermore, the acid solution in step S2 and step S3 is one of phosphoric acid or acetic acid solutions with a mass fraction of 25%.

[0021] Furthermore, the temperature during the glue extraction in step S4 is 50°C.

[0022] By adopting this technical solution, 50°C is conducive to ensuring the uniformity of glue extraction.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. Use polyvinyl alcohol to modify the original solution, generate ether bonds to block hydrophilic groups during the reaction to achieve the purpose of improving water resistance, while reducing the formaldehyde concentration in the solution. Combined with the formaldehyde scavenger to capture free formaldehyde molecules, the number of free formaldehyde molecules carried by the binder after preparation is greatly reduced, thereby greatly reducing the amount of formaldehyde released after the binder is used in the production of regenerated composite keels, solving the problem of excessive formaldehyde release from the binder affecting personnel health when using regenerated composite keels.

[0025] 2. The entire adhesive production process only relies on the reactor being heated to 80°C and the reactor's own insulation function to complete. It does not require high-temperature heating or repeated switching of high and low temperatures, which reduces the difficulty of production operations, saves production energy consumption, and greatly improves production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The present invention is a schematic diagram of the process flow of the method for preparing the adhesive for making the regenerated composite keel. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0028] Please refer to the attached Figure 1 The present invention provides a method for preparing a binder for making a regenerated composite keel, comprising the following steps: S1, adding a formaldehyde aqueous solution into a reaction kettle at room temperature, and then adding polyvinyl alcohol into the formaldehyde aqueous solution; S2, adding an industrial chemical formaldehyde scavenger and urea into the solution obtained in step S1, and heating the solution to 80°C, and then stopping the gas and keeping the temperature for 30 minutes, and then adjusting the pH to 4.6 with an acid solution to continue the reaction; S3, when the solution obtained in step S2 appears dispersed, adjusting the pH to 5.4 with an acid solution, and adding urea and melamine to continue the reaction; S4, stopping the operation of the reaction kettle, adding urea and light calcium carbonate into the solution obtained in step S3, reacting, and naturally cooling at room temperature, and then extracting glue to obtain a binder;

[0029] Polyvinyl alcohol is used to modify the original solution, and ether bonds are generated during the reaction to block hydrophilic groups to achieve the purpose of improving water resistance. At the same time, the formaldehyde concentration in the solution is reduced, and the formaldehyde scavenger is used to capture free formaldehyde molecules, which greatly reduces the number of free formaldehyde molecules carried by the adhesive after preparation, thereby greatly reducing the amount of formaldehyde released after the adhesive is used in the production of regenerated composite keels, solving the problem of excessive formaldehyde release from the adhesive affecting personnel health when using regenerated composite keels; the entire adhesive production process only relies on the reactor being heated to 80°C and cooperating with the reactor's own insulation function to complete, without the need for high-temperature heating or repeated conversion of high and low temperatures, reducing the difficulty of production operations, while saving production energy consumption and greatly improving production efficiency.

[0030] Furthermore, step S1 comprises: dissolving formaldehyde in water to obtain a formaldehyde aqueous solution, wherein the mass ratio of formaldehyde to water is 6 to 7, so as to dilute the formaldehyde and reduce the initial dosage of the formaldehyde.

[0031] Furthermore, in order to control the amount of urea added, the molar ratio of formaldehyde to the sum of urea added three times in steps S2 to S4 is set to 0.65.

[0032] Furthermore, in order to effectively generate a stable high molecular polymer by polycondensation reaction with free formaldehyde molecules to reduce the formaldehyde release, the industrial chemical formaldehyde scavenger in step S2 is set to be a resorcinol solution.

[0033] Furthermore, in step S2, the heating rate of the solution is controlled to be 1°C / 1.5min. The heating rate is controlled to extend the reaction time to ensure that the normal reaction between the substances can be carried out at 80°C. At the same time, it can avoid the temperature increasing too fast to affect the performance of the substances themselves and the production accuracy.

[0034] Furthermore, the acid solution in step S2 and step S3 is one of phosphoric acid or acetic acid solutions with a mass fraction of 25%.

[0035] Furthermore, the temperature during glue extraction in step S4 is 50° C., which is conducive to ensuring the uniformity of glue extraction.

[0036] Exemplarily, the binder prepared in the above embodiment is used to make a regenerated composite keel. The binder is evenly sprayed on the glass fiber mesh cloth, and then wrapped on the surface of the inner core rod of the keel. The regenerated composite keel is made by hot pressing, cooling and curing. The regenerated composite keel is subjected to the following tests:

[0037] According to the national standard GB / T 17657-2013 "Test methods for physical and chemical properties of wood-based panels and veneer wood-based panels", the wet bonding strength of the specimen after being immersed in 63°C hot water for 3 hours is above 1.0Mpa, which can meet the water resistance requirements of the national standard GB / T 9846-2015 "Ordinary plywood" for Class II boards;

[0038] According to the national standard GB / T 17657-2013 "Test methods for physical and chemical properties of wood-based panels and veneer wood-based panels", the 3 The formaldehyde emission of the board was tested by the climate chamber method. The test results showed that the formaldehyde emission was 0.03-0.05 mg / m 3 Between, reaching E0 level environmental protection standard;

[0039] A four-point bending strength test was conducted on it, and the strength value was between 28 and 32Mpa, which meets the project requirements. It is also lower in cost than ordinary wood, has a higher turnover rate, has higher economic benefits, is green, environmentally friendly, low-carbon and energy-saving.

[0040] The present invention is described in detail above in conjunction with the embodiments of the accompanying drawings. A person skilled in the art can make various variations of the present invention according to the above description. Therefore, certain details in the embodiments should not constitute a limitation of the present invention, and the scope of protection of the present invention shall be defined by the scope of the attached claims.

Claims

1. A method for preparing an adhesive for making a regenerated composite keel, characterized in that: The steps include: S1. Adding formaldehyde aqueous solution into a reaction kettle at room temperature, and then adding polyvinyl alcohol into the formaldehyde aqueous solution; S2, adding industrial chemical formaldehyde scavenger and urea to the solution obtained in step S1, and heating the solution to 80° C., then stopping the gas and keeping the temperature for 30 minutes, and then adjusting the pH to 4.6 with an acid solution to continue the reaction; S3. When the solution obtained in step S2 is dispersed, an acid solution is used to adjust the pH to 5.4, and urea and melamine are added to continue the reaction; S4, stopping the operation of the reactor, adding urea and light calcium carbonate to the solution obtained in step S3, reacting and naturally cooling at room temperature, and then extracting glue to obtain a binder.

2. The method for preparing the adhesive for making the regenerated composite keel according to claim 1, characterized in that: Step S1 comprises: dissolving formaldehyde in water to obtain a formaldehyde aqueous solution, wherein the mass ratio of formaldehyde to water is 6-7.

3. The method for preparing the adhesive for making the regenerated composite keel according to claim 1, characterized in that: The molar ratio of the formaldehyde to the total amount of urea added three times in steps S2 to S4 is 0.

65.

4. The method for preparing the adhesive for making the regenerated composite keel according to claim 1, characterized in that: In step S2, the mass ratio of the industrial chemical formaldehyde scavenger to urea is 0.4 to 0.

6.

5. The method for preparing the adhesive for making the regenerated composite keel according to claim 1, characterized in that: In step S2, the industrial chemical formaldehyde scavenger is a resorcinol solution.

6. The method for preparing the adhesive for making the regenerated composite keel according to claim 1, characterized in that: In step S2, the heating rate of the solution is controlled to be 1°C / 1.5min.

7. The method for preparing the adhesive for making the regenerated composite keel according to claim 1, characterized in that: The acid solution in step S2 and step S3 is either a phosphoric acid solution or an acetic acid solution with a mass fraction of 25%.

8. The method for preparing the adhesive for making the regenerated composite keel according to claim 1, characterized in that: The temperature during the glue extraction in step S4 is 50°C.

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