System for continuously producing methylated melamino-formaldehyde resin

Abstract

The utility model discloses a system for continuously producing methylated melamino-formaldehyde resin, which comprises a raw material storage tank A and a raw material storage tank B. The raw material storage tank A is connected with a micro-channel reactor A. A discharge port of the micro-channel reactor A is connected with a precooling pipe. A discharge port of the pre-cooling pipe and a discharge port of the raw material storage tank B are respectively connected with the micro-channel reactor B, and a discharge port of the micro-channel reactor B is connected with the receiving storage tank. According to the utility model, the reaction is continuously carried out in the micro-channel reactor, the raw material can be a high-solid-content raw material, the energy consumption and the raw material consumption are low, the quality difference of products among batches is small, and the production cost is reduced.

Description

Technical Field

[0001] The utility model relates to a system for producing methyl etherified melamine formaldehyde resin, in particular to a microchannel reaction system for continuously producing methyl etherified melamine formaldehyde resin, belonging to the technical field of etherified amino resin production equipment. Background Art

[0002] Methylated melamine formaldehyde resin is one of the most widely used adhesives. In addition to being used in the rubber industry, it is also used in the coating industry. Methylated melamine formaldehyde resin can be divided into high methylated melamine formaldehyde resin (HMMM), high imino and partially methylated melamine formaldehyde resin according to the different functional groups. In the coating industry, HMMM is widely used as a curing additive crosslinking agent in coils and automotive coatings due to its self-polymerization and rapid crosslinking properties. In the rubber industry, HMMM is used as a resorcinol acceptor adhesive in combination with a resorcinol donor, generally in combination with a resorcinol donor or a reinforcing resin to generate a thermosetting resin to bond rubber to skeleton materials such as steel wire. Etherified melamine formaldehyde resin is suitable as a curing agent for coatings such as coils and automobiles.

[0003] At present, the production process of etherified amino resin in China mostly adopts the preparation method of batch reaction in reactor. This batch preparation method has the problem of product quality difference between each batch, and the process is cumbersome and inconvenient to operate. The traditional reactor synthesis process is cumbersome, the reaction time is long, the reaction selectivity is difficult to control, and the product quality is not high. It is of great significance to optimize its reactor process.

[0004] CN112940210A discloses a method for continuously preparing methylated melamine formaldehyde resin. The production process of the method is carried out in the same pipeline. The patent restricts the reaction parameters, but does not describe the production equipment used in detail, nor does it propose a solution for accurately feeding high-solid-content raw materials. Utility Model Content

[0005] In view of the shortcomings of the prior art, the utility model provides a system for continuously producing methylated melamine formaldehyde resin. The system adopts a microchannel reactor to continuously produce methylated melamine formaldehyde resin. The raw material can be a suspension with a high solid content, and a continuous reaction can be achieved, thereby improving production efficiency and reducing product quality differences between batches.

[0006] The technical solution provided by the utility model is as follows:

[0007] A system for continuously producing methylated melamine formaldehyde resin comprises a raw material storage tank A and a raw material storage tank B. The raw material storage tank A is connected to a microchannel reactor A. The discharge port of the microchannel reactor A is connected to a precooling pipe. The discharge port of the precooling pipe and the discharge port of the raw material storage tank B are respectively connected to the microchannel reactor B. The discharge port of the microchannel reactor B is connected to a receiving storage tank.

[0008] Furthermore, the function of the precooling tube is to cool the material after the hydroxylation reaction. The precooling tube is a pipe with an inner diameter of 3.5-4.5 mm and a length of 1-1.1 m. The pipe can be arranged in various ways, for example, in order to save floor space, it can be arranged in an S shape. The precooling tube is provided with a jacket outside to maintain the temperature, and circulating water at 30-40°C is provided in the jacket.

[0009] Furthermore, the raw material storage tank A is used to hold the hydroxylated raw material, which is a solid-liquid mixture, which is a solid-liquid mixture of melamine and formaldehyde solution, and the pH is adjusted to 8-9 with liquid alkali. The raw material storage tank A is provided with a stirring device for stirring the material in the raw material storage tank A so that the hydroxylated raw material is always in a uniform turbid liquid state. In addition, in order to further prevent the hydroxylated raw material in the raw material storage tank A from solidifying, methanol can be added to the solid-liquid mixture of melamine and formaldehyde solution in the raw material storage tank A to a methanol mass fraction of 10-15% to prevent solid agglomeration.

[0010] Further, the microchannel reactor A is a hydroxylation reactor. The microchannel reactor A is a tubular microchannel reactor. The arrangement of the pipes in the tubular microchannel reactor can be an "S" type or the like. The microchannel reactor A is provided with a heat preservation jacket for maintaining the required temperature of the microchannel reactor.

[0011] Preferably, the microchannel reactor A of the utility model comprises a tube body, a row of concave-convex structures is arranged on the top of the inner wall of the tube body, and a row of concave-convex structures is arranged on the bottom, and the concave-convex structures extend from the feed end to the discharge end. Therefore, the presence of the concave-convex structure forms a curved fluid channel in the microchannel reactor A, so that a curved microchannel is formed inside the microchannel reactor A. The microchannel can effectively prevent the high-solid content material from mixing back, and at the same time increase the flow rate of the high-solid content material in the microchannel, so that the material is not easy to gather and clog.

[0012] Preferably, the concave-convex structure is composed of a plurality of irregular protrusions, the top surface, bottom surface, front surface, back surface and one side surface of the protrusion are planes, and the other side surface is a curved surface. The edge of the curved surface is preferably wavy.

[0013] Preferably, the diameter of the microchannel reactor A is 3-4 mm, the length is 2-3 m, the height of the protrusions is 1.0-3.0 mm, and the interval between the protrusions is 1.0-3.0 mm.

[0014] Preferably, the raised cambered surfaces at the bottom of the microchannel reactor A are uniformly installed in one direction, and the raised cambered surfaces at the top are uniformly installed in one direction, and the installation direction of the raised cambered surfaces at the top is opposite to that of the raised cambered surfaces at the bottom.

[0015] Preferably, the protrusions at the bottom and the protrusions at the top of the microchannel reactor A are arranged crosswise rather than oppositely.

[0016] Furthermore, a transfer pump A is provided on the pipeline connecting the raw material storage tank A and the microchannel reactor A. The transfer pump A is preferably a screw pump, which can feed the solid-liquid mixed material into the reactor evenly and smoothly at a certain flow rate and stably feed it for a long time.

[0017] Further, the microchannel reactor B is an etherification reactor, and the microchannel reactor B is an acid- and alkali-resistant pipeline microchannel reactor, and the diameter of the microchannel reactor B is 4.5-5.5 mm and the length is 2-3 m. The arrangement of the pipeline in the microchannel reactor B can be an "S" type or the like. The microchannel reactor B is provided with a heat preservation jacket for maintaining the temperature required by the microchannel reactor.

[0018] Further, the precooling pipe and the raw material storage tank B are connected to the microchannel reactor B through a tee. Among them, one branch of the tee is connected to the discharge port of the precooling pipe, the other branch of the tee is connected to the discharge port of the raw material storage tank B, and the other branch of the tee is connected to the microchannel reactor B.

[0019] Furthermore, the raw material storage tank B is used to hold a mixture of methanol and concentrated nitric acid. A material transfer pump B is provided on the pipeline connecting the raw material storage tank B and the microchannel reactor B. The material transfer pump B is preferably a plunger pump.

[0020] Furthermore, thermometers are provided between the microchannel reactor A and the precooling tube, between the precooling tube and the microchannel reactor B, and between the microchannel reactor B and the receiving tank for real-time detection of the temperature at the critical stage of the entire reaction to ensure the normal progress of the reaction.

[0021] Furthermore, a back pressure valve is provided between the microchannel reactor B and the receiving tank.

[0022] Furthermore, the system also includes a scraper evaporator, which is connected to a receiving tank. The reaction materials in the receiving tank enter the scraper evaporator for continuous distillation. The scraper evaporator adopts negative pressure distillation and controls the feed flow rate to ensure that the product at the evaporator outlet is qualified.

[0023] Compared with the prior art, the technical solution provided by the utility model has the following beneficial effects:

[0024] 1. The system of the utility model can realize continuous reaction, the temperature of the microchannel tube is controllable, the reaction temperature is maintained stable, and the safety is high.

[0025] 2. The microchannel reactor A of the utility model is provided with a special structure and an arranged convex structure, so that the gaps in the channels inside the reactor form microchannels, which can effectively prevent the back-mixing of high-solid content materials, and at the same time increase the flow rate of high-solid content materials in the microchannels, making it difficult for the materials to aggregate and clog.

[0026] 3. The microchannel reactor A of the utility model adopts a screw pump to transport the hydroxylated solid-liquid mixed raw materials, and at the same time, with the reaction process, it can accurately and stably feed the high-solid content raw materials and make the reactants reach a uniform phase.

[0027] 4. Compared with intermittent reaction under the same production capacity, the energy consumption of the system of the utility model is greatly reduced, the raw material consumption is also greatly reduced, the production cost is reduced, and the difference between product batches is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the utility model. For ordinary technicians in this field, other embodiments can be obtained based on these drawings without paying creative work.

[0029] Figure 1 The utility model is a schematic diagram of the structure of a system for continuously producing methyl etherified melamine formaldehyde resin.

[0030] Figure 2 It is a schematic diagram of the protrusion in the microchannel reactor A of the utility model.

[0031] In the figure, 1 is the raw material storage tank A, 2 is the material transfer pump A, 3 is the microchannel reactor A, 4 is the first thermometer, 5 is the precooling tube, 6 is the raw material storage tank B, 7 is the material transfer pump B, 8 is the second thermometer, 9 is the microchannel reactor B, 10 is the third thermometer, 11 is the back pressure valve, 12 is the receiving tank, and 13 is the conveying direction of the hydroxylation reaction material. DETAILED DESCRIPTION

[0032] The following will be combined with the specific embodiments of the utility model to clearly and completely describe the technical solution of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0033] Example 1

[0034] like Figure 1 As shown, the system of the utility model for continuously producing methyl etherified melamine formaldehyde resin comprises a raw material storage tank A1, a microchannel reactor A3, a precooling pipe 5, a raw material storage tank B6, a microchannel reactor B9, and a receiving tank 12; the microchannel reactor A is a hydroxylation reactor, and the microchannel reactor B is an etherification reactor. The discharge port of the raw material storage tank A is connected to the feed port of the microchannel reactor A through a pipeline, the discharge port of the microchannel reactor A is connected to the feed port of the precooling pipe through a pipeline, the discharge port of the precooling pipe and the discharge port of the raw material storage tank B are respectively connected to the two branch pipes of the tee through a pipeline, the third branch pipe of the tee is connected to the feed port of the microchannel reactor B through a pipeline, the discharge port of the microchannel reactor B is connected to the feed port of the receiving tank through a pipeline, and a back pressure valve 11 is provided on the pipeline.

[0035] Furthermore, a stirrer is provided on the top of the raw material storage tank A, and a hydroxylated solid-liquid mixture formed by solid melamine and formaldehyde solution is contained in the raw material storage tank A. The stirrer in the raw material storage tank A can make the solid-liquid mixture raw material in a uniform state. In order to prevent the material from agglomerating, methanol can also be added to the raw material storage tank A, and the mass fraction of methanol is 10-15%. The pH of the hydroxylated solid-liquid mixture is 8-9, which is adjusted by adding liquid alkali.

[0036] Furthermore, a transfer pump A2 is provided on the pipeline between the raw material storage tank A and the microchannel reactor A to pump the material in the raw material storage tank A into the microchannel reactor A. Preferably, the transfer pump A is a screw pump, which can feed the high solid content mixed material continuously and at a uniform speed.

[0037] Furthermore, the microchannel reactor A is a tubular microchannel reactor. Figure 2As shown, the microchannel reactor A includes a tube body, and a plurality of protrusions are arranged at the top of the inner wall of the tube body, and the protrusions are evenly distributed on the top inside and arranged in a straight line, from the feed end to the discharge end. Similarly, a plurality of protrusions are evenly arranged in a straight line at the bottom of the tube body, and the protrusions are also arranged from the feed end to the discharge end. The protrusions are irregular, and the top, bottom, front, back and one side of the protrusions are planes, and the other side is an arc surface, and the edge of the arc surface is wavy. The protrusions at the top and the protrusions at the bottom are arranged crosswise, rather than oppositely. The arc surfaces of the protrusions at the bottom are in the same direction, the arc surfaces of the protrusions at the top are in the same direction, and the arc surfaces of the protrusions at the top and the arc surfaces of the protrusions at the bottom are in opposite directions. For example, the arc surfaces of the protrusions at the bottom are all facing the feed end, and the arc surfaces of the protrusions at the top are all facing the discharge end; or, the arc surfaces of the protrusions at the bottom are all facing the discharge end, and the arc surfaces of the protrusions at the top are all facing the feed end. The microchannel reactor A has a tube diameter of 3-4 mm, a length of 2-3 m, a protrusion height of 1.0-3.0 mm, and a spacing of 1.0-3.0 mm. The special internal structure of the microchannel reactor A forms a curved fluid channel in the microchannel reactor A, which can effectively prevent the high-solid content material from mixing back, and at the same time increase the flow rate of the high-solid content material in the microchannel, making it difficult for the material to aggregate and clog.

[0038] Furthermore, the precooling tube is a pipe with an inner diameter of 3.5-4.5 mm and a length of 1-1.1 m, and the pipe can be arranged in various ways, for example, in an S-shaped arrangement to save floor space. A jacket is provided outside the precooling tube to maintain the temperature, and circulating water at 30-40°C is provided inside the jacket. Alternatively, the precooling tube can be directly placed in a container with circulating water to control the temperature.

[0039] Furthermore, the microchannel reactor B is an acid- and alkali-resistant pipeline microchannel reactor, the diameter of the tube is 4.5-5.5 mm, and the length is 2-3 m.

[0040] Furthermore, the raw material storage tank B is used to hold a mixture of methanol and concentrated nitric acid. A material transfer pump B7 is provided on the pipeline connecting the raw material storage tank B and the microchannel reactor B. The material transfer pump B is preferably a plunger pump.

[0041] Furthermore, both microchannel reactor A and microchannel reactor B are tubular microchannel reactors, and the arrangement of the pipelines can adopt the arrangement disclosed in the prior art, such as S type, M type, etc. Microchannel reactor A and microchannel reactor B are both provided with jackets to maintain the reaction temperature.

[0042] Furthermore, a first thermometer 4 is arranged between the microchannel reactor A and the precooling tube, a second thermometer 8 is arranged between the precooling tube and the microchannel reactor B, and a third thermometer 10 is arranged between the microchannel reactor B and the receiving tank, so as to accurately monitor the temperature of each stage of the reaction.

[0043] Furthermore, the discharge port of the receiving storage tank can also be connected to a scraper evaporator, and the reaction materials enter the scraper evaporator for continuous distillation and filtration to obtain a methyl etherified amino resin product.

[0044] When the utility model is used to produce methyl etherified melamine formaldehyde resin, the following process is included:

[0045] 1. Mix melamine and formaldehyde solution evenly in raw material storage tank A, add liquid alkali to adjust the pH to 8-9, add 10-15wt% methanol, mix evenly and set aside; mix methanol and concentrated nitric acid evenly in raw material storage tank B and set aside;

[0046] 2. The raw materials in the raw material storage tank A are pumped into the microchannel reactor A through the transfer pump A for hydroxylation reaction, the reaction temperature is 95-110°C, and the residence time is 5-10min. The material flowing out of the microchannel reactor A enters the precooling tube to cool the material, the temperature of the precooling tube is 30-40°C, and the residence time is 3-4min. Then the material in the precooling tube and the material in the raw material storage tank B enter the microchannel reactor B through the three-way, and the material undergoes etherification reaction in the microchannel reactor B, the reaction temperature is 40-60°C, and the residence time is 2-3min.

[0047] 3. After the etherification reaction, the material flows out of the microchannel reactor B and enters the receiving tank, where the pH is adjusted to 8-9 with liquid alkali, and then passed into the scraper evaporator for continuous vacuum distillation, and the methyl etherified amino resin product is obtained after filtration.

[0048] Example 2

[0049] The system for continuously producing methylated melamine formaldehyde resin in Example 1 was used to produce methylated melamine formaldehyde resin, wherein the reaction temperature of the material in microchannel reactor A was 105° C., the retention time was 7.5 min, the temperature of the material in the precooling tube was 30° C., the residence time was 3 min, and the reaction temperature of the material in microchannel reactor B was 50° C., the retention time was 2 min. The final yield of methylated melamine formaldehyde resin was 92.35%.

[0050] The above shows and describes the basic principle, main features and advantages of the utility model. Those skilled in the art should understand that the utility model is not limited by the above embodiments. The above embodiments and descriptions are only for explaining the principle of the utility model. Without departing from the spirit and scope of the utility model, the utility model may have various changes and improvements, which fall within the scope of the utility model to be protected. The scope of protection of the utility model is defined by the attached claims and their equivalents.

[0051] The matters not described in detail in the present invention are all known technologies to those skilled in the art.

Claims

1. A system for continuously producing methylated melamine formaldehyde resin, characterized in that: It includes a raw material storage tank A and a raw material storage tank B, wherein the raw material storage tank A is connected to a microchannel reactor A, the discharge port of the microchannel reactor A is connected to a precooling pipe, the discharge port of the precooling pipe and the discharge port of the raw material storage tank B are respectively connected to the microchannel reactor B, and the discharge port of the microchannel reactor B is connected to a receiving tank.

2. The system according to claim 1, characterized in that: The raw material storage tank A is used to contain hydroxylation raw materials; a stirring device is provided in the raw material storage tank A.

3. The system according to claim 1, characterized in that: A material transfer pump A is provided on the pipeline connecting the raw material storage tank A and the microchannel reactor A, and a material transfer pump B is provided on the pipeline connecting the raw material storage tank B and the microchannel reactor B.

4. The system according to claim 3, characterized in that: The transfer pump A is a screw pump, and the transfer pump B is a plunger pump.

5. The system according to claim 1, characterized in that: The microchannel reactor A and the microchannel reactor B are both tubular microchannel reactors.

6. The system according to claim 1 or 5, characterized in that: The diameter of the microchannel reactor A is 3-4 mm and the length is 2-3 m; the diameter of the microchannel reactor B is 4.5-5.5 mm and the length is 2-3 m; the diameter of the precooling tube is 3.5-4.5 mm and the length is 1-1.1 m.

7. The system according to claim 1 or 5, characterized in that: The microchannel reactor A comprises a tube body, and a plurality of protrusions are arranged on the top and bottom of the inner wall of the tube body. The protrusions on the top and bottom are arranged in a straight line, so that a curved fluid channel is formed in the microchannel reactor A.

8. The system according to claim 7, characterized in that: The top surface, bottom surface, front surface, back surface and one side surface of the protrusion are flat, and the other side surface is an arc surface, and the edge of the arc surface is wavy; the protrusion on the top and the protrusion on the bottom are cross-arranged, the arc surfaces of the protrusions on the bottom are oriented in the same direction, and the arc surfaces of the protrusions on the top are oriented in the same direction, and the arc surfaces of the protrusions on the top and the protrusions on the bottom are oriented in opposite directions.

9. The system according to claim 7, characterized in that: The height of the protrusions is 1.0-3.0 mm, and the interval between the protrusions is 1.0-3.0 mm.

10. The system according to claim 1, characterized in that: Thermometers are provided between the microchannel reactor A and the precooling tube, between the precooling tube and the microchannel reactor B, and between the microchannel reactor B and the receiving tank; a back pressure valve is provided between the microchannel reactor B and the receiving tank, and the receiving tank is connected to the scraper evaporator.

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