MDI raw material liquefaction dropping reaction device for hot melt adhesive production

Abstract

The utility model discloses a kind of MDI raw material liquefaction dropwise adding reaction devices for hot melt adhesive production, it is related to hot melt adhesive production technical field.The utility model includes storage tank, and the main conveying pipe is installed at the bottom of storage tank, and the main liquid pump is installed in the side of main conveying pipe, and the main flowmeter is installed in the side of main liquid pump, and the multiple sub-droplet delivery pipes are installed in the side of main conveying pipe away from storage tank, and the sub-liquid pump is installed in the side of sub-droplet delivery pipe, and the sub-flowmeter is installed in the side of sub-liquid pump, and the reaction kettle partition is communicated at the bottom of sub-droplet delivery pipe, and each reaction kettle partition is dispersed at different positions inside reaction kettle.The utility model by MDI is pre-stored to the storage tank of setting heat preservation layer, and multiple groups of sub-droplet delivery pipes that can carry out flow control are set in the bottom of storage tank, the multiple-point speed control delivery of MDI raw material in reaction kettle can be realized, and thus avoid gel production and improve production efficiency.

Description

Technical Field

[0001] This utility model belongs to the field of hot melt adhesive production technology, specifically relating to an MDI raw material liquefaction and dripping reaction device for hot melt adhesive production. Background Technology

[0002] MDI (diphenylmethane diisocyanate) and polyols are the two main raw materials for producing hot melt adhesives. During production, both polyols and MDI need to be put into a reaction vessel and a small amount of resin and catalysts are added to react.

[0003] In existing technologies, MDI is added to the reactor in solid form in a single step. The drawbacks of this method are twofold: firstly, solid MDI requires a relatively long time to dissolve or melt within the reactor, which affects the uniformity of material mixing and the reaction rate in the initial stages of the reaction; secondly, a single addition results in an excessively high concentration of MDI below the addition port in the reactor, leading to an imbalance in the reaction ratio between MDI and the polyol. Furthermore, the rapid temperature rise during concentrated reactions can trigger side reactions that generate large amounts of gel, and the localized concentrated heat release increases the difficulty of temperature control, posing safety hazards.

[0004] No effective solutions have yet been proposed to address the problems in the relevant technologies. Utility Model Content

[0005] The purpose of this utility model is to provide an MDI raw material liquefaction and dripping reaction device for hot melt adhesive production. The technical problem to be solved is as follows: In the existing hot melt adhesive production, the solid MDI added into the reactor is prone to generating a by-product gel, and there is also the problem of uncontrollable reaction temperature.

[0006] The objective of this utility model can be achieved through the following technical solutions: A liquefaction and dripping reaction apparatus for MDI raw material in hot melt adhesive production includes a storage tank. A main delivery pipe is installed at the bottom of the storage tank. A main liquid pump is installed on one side of the main delivery pipe, and a main flow meter is installed on one side of the main liquid pump. Multiple dripping pipes are installed on the side of the main delivery pipe away from the storage tank. A distributor pump is installed on one side of each dripping pipe, and a distributor flow meter is installed on one side of each distributor pump. The bottom end of each dripping pipe is connected to a reaction vessel partition, and each reaction vessel partition is distributed at different locations inside the reaction vessel.

[0007] As a further embodiment of this utility model, an insulation layer is installed on the outer side of the storage tank.

[0008] As a further aspect of this utility model, the internal temperature of the storage tank is 40-60℃.

[0009] As a further embodiment of this invention, the main liquid pump is electrically connected to each of the dispensing pumps.

[0010] As a further aspect of this invention: the dripping speed of the dripping tube is slower in the initial stage of the reaction than in the later stage of the reaction.

[0011] As a further embodiment of this invention: the reaction vessel is divided into the stirring vortex zone, the inner wall, and the bottom within the reaction vessel.

[0012] The beneficial effects of this utility model are: 1. By installing an insulation layer on the outside of the MDI storage tank, the MDI inside the tank is maintained in a suitable liquid state for reaction. A main delivery pipe is installed at the bottom of the tank, and multiple drip delivery pipes are installed at the ends of the main delivery pipe. Each pipe is equipped with a liquid pump and a flow meter, and the ends of each drip delivery pipe are distributed to various sections within the reactor. During use, liquid MDI can be distributed to various points within the reactor through the drip delivery pipes, thereby matching the rate of heat generation and heat dissipation. This avoids the rapid temperature rise caused by the local accumulation of MDI and the formation of concentrated reactions. The technical advantage is that liquefying MDI and distributing it to multiple points can maintain the controllability and safety of the reaction temperature within the reactor, and can also avoid the formation of reaction byproducts such as gel due to excessive local reaction heat, thus improving the quality of the reaction product. Furthermore, since the main delivery pipe and each drip delivery pipe are equipped with liquid pumps and flow meters, the flow control unit formed by each liquid pump and flow meter can control the real-time rate of MDI delivery. This allows for the adjustment of the reaction state at each stage of the production process to adapt to the reaction characteristics of the raw materials, thereby effectively improving production efficiency while ensuring the quality of the finished product.

[0013] 2. By installing an insulation layer on the outside of the storage tank, the temperature inside the MDI storage tank is controlled between 40 and 60 degrees Celsius, so that MDI is always kept in a suitable liquid active state for reaction. That is, it is always ready as a raw material. When it is fed into the reactor, it can achieve the function of immediate reaction upon addition. Moreover, the liquid state and the multi-point dripping method allow MDI to be quickly dispersed in the reactor and uniformly mixed with polyol, thereby effectively improving the production speed of hot melt adhesive. Attached Figure Description

[0014] The present invention will be further described below with reference to the accompanying drawings.

[0015] Figure 1 This is a schematic diagram of the overall structure of this utility model.

[0016] In the diagram: 1. Storage tank; 2. Insulation layer; 3. Main liquid pump; 4. Main flow meter; 5. Main delivery pipe; 6. Diverting pipe; 7. Diverting pump; 8. Diverting flow meter; 9. Reactor section. Detailed Implementation

[0017] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present utility model.

[0018] like Figure 1 As shown, an MDI raw material liquefaction and dripping reaction device for hot melt adhesive production includes a storage tank 1. A main delivery pipe 5 is installed at the bottom of the storage tank 1. A main liquid pump 3 is installed on one side of the main delivery pipe 5. A main flow meter 4 is installed on one side of the main liquid pump 3. Five dripping pipes 6 are installed on the side of the main delivery pipe 5 away from the storage tank 1. A liquid dispensing pump 7 is installed on one side of each dripping pipe 6. A liquid dispensing flow meter 8 is installed on one side of each liquid dispensing pump 7. The bottom end of each dripping pipe 6 is connected to a corresponding reaction vessel section 9. Each reaction vessel section 9 is distributed in different positions inside the reaction vessel. It should be noted that storage tank 1 is a pre-storage tank for MDI. The outer side of storage tank 1 is equipped with a heat insulation layer 2. The heat insulation layer 2 includes, but is not limited to, setting up a heat insulation jacket and setting up a heat tracing pipe for heating. The internal temperature of storage tank 1 is 40 to 60 degrees Celsius. Specifically, since MDI will undergo physical crystallization below 38 degrees Celsius and will undergo rapid chemical degradation and self-polymerization reaction above 60 degrees Celsius, both physical crystallization and chemical degradation will reduce the activity of MDI as a reaction raw material and may block the main delivery pipe 5 and the drip delivery pipe 6. Therefore, it is necessary to maintain the internal temperature of storage tank 1 in the range of 40 to 60 degrees Celsius to maintain the liquid state of MDI, so that it can be used immediately as a backup reaction raw material. Both the main liquid pump 3 and the distributor pump 7 are used to transport liquid MDI. The main flow meter 4 and the distributor flow meter 8 are used to measure the total output flow of MDI and the flow delivered to each drop delivery pipe 6, respectively. Specifically, the main liquid pump 3 and the main flow meter 4 are integrated into a metering pump, which is suitable for small-batch hot melt adhesive production with high production accuracy. When hot melt adhesive production is continuous and the production accuracy requirement is low, the metering pump can be replaced by a flow meter and a regulating valve. Furthermore, the main liquid pump 3 and each of the distributor pumps 7 are electrically connected. Therefore, in actual flow control, preferably, a PLC controller can be installed between the main liquid pump 3 and each distributor pump 7 to control the flow rate of MDI at each reaction stage, thereby controlling the reaction progress. Specifically, the flow rate of the main liquid pump 3 and each distributor pump 7 is slower in the initial stage of the reaction, and faster in the later stage. This is because, in the initial stage, the reaction in the reactor has not yet been fully completed, resulting in a lower viscosity of the mixed reactants and improved contact between MDI and the polyol. The high reaction rate leads to a rapid temperature rise. To avoid excessively high temperatures and gel formation, the rate at which MDI is added to the reactor needs to be slowed down. In the later stages of the reaction, the reactants in the reactor are almost completely mixed, resulting in extremely high viscosity and restricted molecular chain movement. Rapidly adding MDI can increase its contact rate with the polyol, thereby appropriately increasing the reaction temperature. The increase in reaction temperature effectively reduces the viscosity of the reaction mixture, thereby increasing the reaction rate and shortening the reaction cycle. In other words, the function of accelerating the reaction rate is achieved by controlling the MDI addition rate at different reaction stages.

[0019] Preferably, each reaction vessel section 9 is located in the stirring vortex zone, the inner wall of the reaction vessel, and the bottom of the reaction vessel, respectively. It should be noted that the bottom end of the drip delivery pipe 6 extends into the reaction vessel section 9 at, but is not limited to, these three locations. The purpose is to guide the MDI delivered by each drip delivery pipe 6 to various locations within the reaction vessel, thereby improving the uniformity of the reaction and avoiding the local enrichment and heating effect of MDI, thus preventing gel formation. In addition, care should be taken to avoid leading the end of the drip delivery pipe 6 to the dead corner of the stirring area.

[0020] The above description provides a detailed account of one embodiment of the present invention. However, this description is merely a preferred embodiment and should not be construed as limiting the scope of the present invention. All equivalent variations and improvements made within the scope of the claims of the present invention should still fall within the patent coverage of the present invention.

Claims

1. A device for the liquefaction and dripping reaction of MDI raw materials for hot melt adhesive production, characterized in that, The system includes a storage tank (1), a main delivery pipe (5) installed at the bottom of the storage tank (1), a main liquid pump (3) installed on one side of the main delivery pipe (5), a main flow meter (4) installed on one side of the main liquid pump (3), multiple drip delivery pipes (6) installed on the side of the main delivery pipe (5) away from the storage tank (1), a liquid distribution pump (7) installed on one side of the liquid distribution pipe (6), a liquid distribution flow meter (8) installed on one side of the liquid distribution pump (7), and a reaction vessel partition (9) connected to the bottom end of the drip delivery pipe (6). Each reaction vessel partition (9) is dispersed in different positions inside the reaction vessel.

2. The MDI raw material liquefaction and dripping reaction apparatus for hot melt adhesive production according to claim 1, characterized in that, The storage tank (1) has an insulation layer (2) installed on its outer side.

3. The MDI raw material liquefaction and dripping reaction apparatus for hot melt adhesive production according to claim 1, characterized in that, The internal temperature of the storage tank (1) is 40-60℃.

4. The MDI raw material liquefaction and dripping reaction apparatus for hot melt adhesive production according to claim 1, characterized in that, The main liquid pump (3) is electrically connected to each of the dispensing pumps (7).

5. The MDI raw material liquefaction and dripping reaction apparatus for hot melt adhesive production according to claim 1, characterized in that, The dripping speed of the dripping tube (6) is slower in the early stage of the reaction than in the later stage.

6. The MDI raw material liquefaction and dripping reaction apparatus for hot melt adhesive production according to claim 1, characterized in that, The reactor partition (9) is located in the stirring vortex zone, inner wall and bottom of the reactor.

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