Integration synthesis process for polyurethane prepolymer synthesis and elastic body pouring and casting machine

Abstract

The invention discloses an integration synthesis process for polyurethane prepolymer synthesis and elastic body pouring, and a hydroxyl-terminated polyurethane prepolymer is directly completed in a retort with the function of material storage on the casting machine. The process comprises the following steps: adding oligomer polyalcohol into the prepolymer retort of the casting machine, heating, then carrying out vacuum dehydration, and cooling to a regulated temperature; adding diisocyanate with a designed quantity in the prepolymer retort, stirring and mixing continuously; carrying out prepolymerization reaction at a required temperature, and then carrying out vacuum defoaming; preparing the free diisocyanate without taking part in reaction and the air bubble wrapped in the stirring process which are qualified after tests into the hydroxyl-terminated polyurethane prepolymer; and then carrying out polyurethane elastomers pouring practice on the same casting machine. The invention can reduce the equipment investment, optimizes the process flow, reduces the labor intensity and environment pollution, can directly complete polyurethane prepolymer synthesis, elastic body pouring and prepolymer filling on the same device.

Description

technical field [0001] The invention relates to an integrated synthesis process of polyurethane prepolymer synthesis and elastomer pouring, and also relates to an integrated synthesis and pouring machine for polyurethane prepolymer synthesis and elastomer pouring. Background technique [0002] Polyurethane elastomers are classified according to product processing methods, including casting type, thermoplastic type, mixing type, etc. Casting type polyurethane elastomer is one of the most important varieties of polyurethane elastomer. The synthesis methods mainly include: two-step method (prepolymer method), one-and-a-half-step method (semi-prepolymer method) and one-step method. Since the mechanical and physical properties of the products produced by the one-step and one-and-a-half-step processes are generally worse than those produced by the two-step process; therefore, most castable polyurethane elastomer products, especially high-modulus products Generally, a two-step pro...

AI Technical Summary

Problems solved by technology

[0008] 1. From the preparation of the prepolymer to the production of cast polyurethane elastomer products on the traditional pouring machine, it needs to be stored for heating, cooling, and defoaming, which consumes a lot of energy

[0009] 2. The prepolymer is unloaded from the reactor, sealed and stored in the storage container, the storage container is transported, the weight is weighed, and the prepolymer storage tank of the traditional pouring machine is fed, and the container and operating tools are checked. Many man-hours are required for cleaning, etc.

[0010] 3. When the prepolymer flows back and forth between the reactor, storage container and traditional pouring machine, it will inevitably overflow, splash, and flow out harmful gases and raw materials, causing environmental pollution

[0011] 4. The prepolymer is easy to chemically react with external active substances during unloading, storage, handling, feeding and storage heating, resulting in changes in the content of active ingredients such as isocyanate groups and affecting product quality

[0013] 1. The traditional pouring machine is not equipped with an independent forced cooling device, does not have an independent forced cooling function, and cannot meet the temperature control requirements of the chemical synthesis of prepolymer synthesis and other material systems that need to be cooled during chemical reactions. Require

[0014] 2. The heating device on the traditional pouring machine is used to heat, heat up and keep warm the prepolymer storage tank and the entire prepolymer material flow system together. When only the prepolymer storage tank is required to be heated, heated and During heat preservation, the equipment will also heat other parts and devices of the entire prepolymer material flow system at the same time, which not only wastes energy, but also causes the remaining materials on the inner wall of these parts to gel and freeze due to long-term "dry burning". It will affect the normal operation of the equipment and accelerate the aging of parts in these parts, especially rubber and plastic products and electrical control components. It is not suitable to use the prepolymer storage tank on the pouring machine for independent operation

[0015] 3. On the traditional pouring machine, the storage tank of each raw material component and the corresponding pipe valve components, metering device, and pouring head form a closed loop. The outlet and return pipelines of each raw material component The discharge valve and the discharge valve are the materials at the bottom of the storage tank of this group of raw materials are input and discharged from the outside, except for the feeding hole on the top of the storage tank (which can also be used to add materials to the storage tank) and pouring The inlet and outlet outside the spray nozzle on the head (which can be used for timing filling of materials in the tank), because of the above-mentioned discharge valve, the discharge valve is generally arranged together with the pipe valve components of the material flow system of the same component, and built into the pouring machine Inside the machine, the space of the operating room is small, which is not convenient for frequent opening and closing of the valve for feeding, discharging and canning operations

[0016] 4. In addition, the convection velocity of the heat transfer medium in the heating jacket of the prepolymer storage tank of the traditional pouring machine is relatively low. It must be higher than a certain distance, so there is a certain length between the discharge and return pipes of the storage tank liner and the bottom interface of the storage tank; There is also a certain length between the material valve and the discharge valve of the return line; in this way, there will be a certain cavity in these pipelines and valves, and the materials in the kettle will react, mix, dehydrate, degas, During defoaming, there will be more raw materials that cannot participate in chemical reactions, mixing, dehydration, degassing, and defoaming due to insufficient stirring and mixing.

However, because of its low shear strength, it cannot achieve the chemical synthesis of prepolymer synthesis and other material systems that require high shear strength stirring during chemical reactions.

[0018] 6. Due to the above reasons, generally only the method of adding the prepared prepolymer to the prepolymer storage tank of the traditional pouring machine can be used to produce cast polyurethane elastomer products.

The preparation of prepolymer needs to be completed by another set of special prepolymer synthesis equipment, which undoubtedly increases the production and investment costs of users

[0019] 7. Therefore, the prepolymer filling operation cannot be completed on the traditional pouring machine; the semi-mechanized and manual production operations of castable polyurethane elastomer products such as low-hardness products using alcohol-amine mixtures as chain-extending cross-linking agents; and other work The temperature ranges from room temperature to 140°C, and the viscosity of the material is 100-3000cP. It is not corrosive to stainless acid-resistant steel (304, etc.), and no matter whether there are heating, cooling, heat preservation requirements, or vacuum dehydration, degassing, and defoaming requirements. Mixing, reaction, filling (including quantitative filling) of materials, etc.

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