White material premixing process, premixing system and application thereof

Abstract

The invention discloses a white material premixing process, a white material premixing system and application of the white material premixing system. The white material is split and premixed, and based on a multi-stage premixing mode, the problem of white material stability in the prior art is solved, so that the foaming quality is improved, and the white material can be used for preparing a foaming heat-insulating material for household appliances such as refrigerators and the like. The invention further provides a white material premixing system and application of the white material premixing process or the white material premixing system.

Description

Technical Field

[0001] The present invention relates to the field of rigid polyurethane foam materials, and particularly to a white material premixing process, a premixing system and their applications. Background Art

[0002] Polyurethane rigid foam is widely used as thermal insulation material for household appliances such as refrigerators, freezers, water heaters, heat pumps, etc. The composition for preparing polyurethane rigid foam includes a black material and a white material. Among them, the black material is usually organic polyisocyanate, and the white material usually includes components such as polyol, foaming agent, catalyst (mainly including organic amine, organic metal catalyst, etc.), and auxiliary agent. Polyurethane rigid foam is prepared by mixing the black material and the white material and then foaming. In the polyurethane foaming process, white material premixing is a preprocess. Through premixing, the components of the white material are mixed evenly, so that a foaming material meeting the use requirements can be prepared after mixing with the black material. There are mainly two conventional white material premixing processes: 1) Mix the components except the foaming agent in advance, and then further add the foaming agent for mixing. Specifically, the upstream supplier can complete the premixing of the components except the foaming agent of the white material, and the electrical appliance manufacturer further adds the foaming agent for use; 2) Mix all the components of the white material in advance and directly use the mixed material in the foaming process.

[0003] Under the background of energy conservation and emission reduction, the development of polyurethane foam with a low thermal conductivity coefficient (thermal conductivity coefficient at 10 °C < 17.0 mW / m·K) has become a research hotspot. For the existing foaming systems based on liquid pentane-based physical foaming agents (cyclopentane, n-pentane, isopentane), chemical foaming agents (water), and low-boiling-point gas foaming agents (such as HFC-152a, HFO-1234ze, etc.), the thermal conductivity coefficient of the prepared polyurethane foam is about 19 mW / m·K (at 10 °C). By using a liquid foaming agent with a lower thermal conductivity coefficient (trans-1-chloro-3,3,3-trifluoropropene, HFO-1233zd(E), abbreviated as LBA, with a boiling point of 19 °C and a gas-phase thermal conductivity coefficient of 10.2 mW / m·K at 20 °C), smaller cell sizes can be obtained, and the thermal conductivity coefficient can be further reduced.

[0004] In actual production, the white material may need to go through a liquid storage tank, a long-distance pipeline, etc. for transition or transportation from the completion of premixing preparation to foaming use. These processes all require a certain amount of time. In case of production line maintenance, legal holidays, weekends, etc., the parking time of the white material is even longer. The conventional premixing process is difficult to ensure the long-term stability and reliability of the white material with LBA as the main foaming agent, resulting in a decrease in foaming quality of the white material in the pipeline or storage tank during long-term storage, and even causing the phenomenon of foaming failure, which has an extremely adverse impact on the energy consumption, strength, etc. of the final product. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. For this purpose, the present invention provides a white material premixing process to improve the stability and reliability of the white material.

[0006] The present invention also provides a white material premixing system.

[0007] The present invention also provides a polyurethane foaming system.

[0008] The present invention also provides a polyurethane foaming method.

[0009] The present invention also provides an application of the above white material premixing process, white material premixing system, polyurethane foaming system or polyurethane foaming method.

[0010] An embodiment of the first aspect of the present invention relates to a white material premixing process, including:

[0011] Providing a preparation raw material including polyol, surfactant, organic amine catalyst, LBA and water;

[0012] Mixing a part of the polyol, a part of the surfactant and the preparation raw material of the organic amine catalyst to form a first mixture;

[0013] Mixing the remaining part of the polyol, the remaining part of the surfactant, the LBA and the preparation raw material of the water to form a second mixture;

[0014] Mixing the first mixture and the second mixture to obtain a white material.

[0015] The white material premixing process according to the embodiment of the first aspect of the present invention has at least the following beneficial effects:

[0016] For the traditional white material premixing process, there is a situation where LBA, organic amine catalyst, water, etc. coexist in a system for a long time, and there are the following risks: LBA is an olefin containing chlorine atoms in its chemical structure, with high chemical activity, and is prone to nucleophilic reaction with traditional organic amine catalysts, generating fluoride ions, chloride ions, and ammonium ions. The above reactions will not only consume the organic amine catalyst and affect the chemical reaction rate in the subsequent polyurethane foaming process, but also make LBA ineffective, affecting the density and thermal conductivity of the foam products.

[0017] During premixing, the white material is split into a water-containing part (corresponding to the second mixture) and a water-free part (corresponding to the first mixture). In the water-free part, the raw materials for preparing the partial polyol, partial surfactant, and organic amine catalyst are premixed. In the water-containing part, the raw materials for preparing the remaining polyol, remaining surfactant, LBA, and water are premixed. While ensuring the dispersion uniformity of the white material, the contact time of easily reactive and easily inactivated components such as LBA and organic amine is reduced, and the long-term stability and reliability of the foaming white material are improved.

[0018] Part of the surfactant and part of the polyol are added simultaneously to the first mixture to improve the mixing uniformity of the organic amine catalyst and this part of the polyol. At the same time, a part of the surfactant and polyol are also added to the second mixture, which is conducive to the uniform mixing of the foaming agent (LBA and water) and the polyol. Therefore, by splitting and adding the polyol and surfactant in the white material, the dispersion uniformity of the white material is improved, and thus the foaming stability and surface quality of the white material after premixing are ensured. If the surfactant is not split, for example, all the surfactant is added to the first mixture, it will affect the component uniformity of the second mixture and is not conducive to the uniform dispersion of the foaming agent in the white material; conversely, if all the surfactant is added to the second mixture, it will affect the component uniformity of the first mixture, especially the dispersion uniformity of the catalyst. Uneven dispersion of the foaming agent or catalyst is likely to cause internal defects or skin defects in the foam, which will ultimately have an adverse effect on the heat insulation performance of the foam. Skin defects will also affect the surface strength and have an adverse effect on the appearance quality of the final product.

[0019] In addition, polyurethane foaming usually uses polyols with high functionality and high hydroxyl value to balance thermal conductivity and strength. Such polyols usually have a certain viscosity, and the viscosity is also strongly related to temperature. The temperature varies throughout the year, and the viscosity also has a large difference. By splitting and adding the polyol, it is beneficial to adjust the viscosities of the first mixture and the second mixture by controlling the splitting ratio of the polyol, so that it can be transported to the production line foaming platform over a long distance through the pipeline, thereby improving the reliability of the material transportation throughout the year (especially in winter) and significantly reducing the system temperature control energy consumption.

[0020] According to some embodiments of the present invention, the mass of the LBA is 10% - 50% of the mass of the polyol.

[0021] According to some embodiments of the present invention, the mass of the LBA is 20% - 50% of the mass of the polyol.

[0022] LBA has a relatively large molecular weight (more parts by mass of the foaming agent are required to achieve the same foam density). When LBA is used as a single physical foaming agent, the application cost is relatively high, and it is suitable for some high-end and ultra-energy-saving products. In contrast, if auxiliary foaming agents such as cyclopentane (with a relatively low unit price) are further added, the amount of LBA can be reduced, and the cost performance can be improved.

[0023] According to some embodiments of the present invention, the mass of the water does not exceed 3% of the mass of the polyol. Appropriately increasing the water content can, to a certain extent, reduce the amount of LBA used, and it can be used to prepare low-thermal-conductivity foams with high cost performance.

[0024] According to some embodiments of the present invention, the mass of the organic amine catalyst is 1% - 10% of the mass of the polyol. The mass of the organic amine catalyst varies depending on the type of polyol. For example, when the average hydroxyl value of the polyol is 350 - 450 mgKOH / g and the average functionality is 4.5 - 6.5, the mass of the organic amine catalyst can be selected as 4% - 6% of the mass of the polyol.

[0025] According to some embodiments of the present invention, the organic amine catalyst is selected from the combination of at least two of a foaming catalyst, a gelling catalyst, and a trimerization catalyst. Among them, the foaming catalyst is selected from one or two of pentamethyldiethylenetriamine and bis(dimethylaminoethyl) ether, the gelling catalyst is selected from one or a combination of more of N,N-dihexylmethylamine, N,N-dimethylcyclohexylamine, and triethylenediamine, and the trimerization catalyst is selected from one or two of tris(dimethylaminopropyl) hexahydrotriazine and 2-hydroxypropyltrimethylformate.

[0026] Among them, the foaming catalyst is used to promote pore formation, the gelling catalyst accelerates the gel reaction and plays a role in stabilizing and fixing the foam, and the trimerization catalyst can increase the foaming rate. Using different combinations of foaming agents is beneficial to form a fine and uniform cell structure.

[0027] According to some embodiments of the present invention, the mass of the foaming catalyst is 0 - 1% of the mass of the polyol.

[0028] According to some embodiments of the present invention, the mass of the gelling catalyst is 2.5% - 6% of the mass of the polyol.

[0029] According to some embodiments of the present invention, the mass of the trimerization catalyst is 0.6% - 3% of the mass of the polyol.

[0030] According to some embodiments of the present invention, the raw materials for preparing the white material further include a first auxiliary foaming agent, and the first auxiliary foaming agent is selected from one or more combinations of pentane-based, HFC-152a (1,1-difluoroethane, CAS No.: 75-37-6), HFO-1234ze (1,3,3,3-tetrafluoro-1-propene, CAS No.: 1645-83-6), and HCFO-1224yd(Z) ((Z)-1-chloro-2,3,3,3-tetrafluoropentene, CAS No.: 111512-60-8). The step of forming the first mixture includes: mixing the raw materials including a part of the polyol, a part of the surfactant, the organic amine catalyst, and the first auxiliary foaming agent to form the first mixture.

[0031] According to some embodiments of the present invention, the raw materials for preparing the white material further include a second auxiliary foaming agent, and the second auxiliary foaming agent is selected from one or more combinations of pentane-based, HFC-152a, HFO-1234ze, and HCFO-1224yd(Z). The step of forming the second mixture includes: mixing the raw materials including the remaining part of the polyol, the remaining part of the surfactant, the LBA, the water, and the second auxiliary foaming agent to form the second mixture.

[0032] Among them, the cyclopentane-based auxiliary foaming agent is selected from one or more combinations of cyclopentane, n-pentane, and isopentane. The molecular weight and unit price of cyclopentane-based compounds are both reduced, and they can be used to replace part of the LBA, reduce the total amount of the foaming agent, and reduce the production cost.

[0033] According to some embodiments of the present invention, the first auxiliary foaming agent and the second auxiliary foaming agent are the same or different.

[0034] According to some embodiments of the present invention, the first auxiliary foaming agent is selected from pentane-based, which has cost and environmental protection advantages; the second auxiliary foaming agent is selected from one or more combinations of HFC-152a, HFO-1234ze, and HCFO-1224yd(Z). These substances have good compatibility with LBA and can improve the dispersion uniformity.

[0035] According to some embodiments of the present invention, the mass of the first auxiliary foaming agent is 0 to 15% of the mass of the polyol.

[0036] According to some embodiments of the present invention, the mass of the second auxiliary foaming agent is 0 to 10% of the mass of the polyol.

[0037] The first auxiliary foaming agent and the second auxiliary foaming agent may not be added, and thus their addition amounts may be 0.

[0038] According to some embodiments of the present invention, the raw materials for preparing the white material further include a nucleating aid, and the white material premixing process further includes: mixing the first mixture, the second mixture and the nucleating aid to obtain the white material; or, the step of forming the second mixture includes: mixing the remaining part of the polyol, the remaining part of the surfactant, a part of the LBA, and the raw materials for preparing the water to form a second mixture; the white material premixing process further includes: mixing the nucleating aid with the raw materials for the remaining part of the LBA to form a third mixture; mixing the first mixture, the second mixture and the third mixture to obtain the white material.

[0039] According to some embodiments of the present invention, the mass ratio of the nucleating aid to the remaining part of the LBA ≥ 1:10.

[0040] The nucleating aid can promote bubble nucleation and is conducive to obtaining smaller cell sizes. When a part of the LBA is used to dilute the nucleating aid, it is convenient for the accurate metering of the nucleating aid and the rectification of the production process. Since the dosage of the nucleating aid is generally small, it is easy to miss adding it, which will have an adverse effect on the thermal conductivity of the foam. At the same time, due to the lack of this part of the LBA for diluting the nucleating aid, the density of the foam will increase. Therefore, it is easy to quickly check the abnormal reason by monitoring the foam density, ensuring the long-term stability and reliability of the production line process. If the nucleating aid is directly added, since the total amount of the foaming agent remains unchanged, the impact on the foam density is small, mainly the abnormal thermal conductivity, which is not conducive to abnormal monitoring (the foam density test is easier to operate and has lower requirements for the production line), and there are many factors affecting the thermal conductivity, including material temperature, material ratio, gun head pressure, and even abnormal polyol raw materials. Therefore, it is difficult to quickly find out the reason.

[0041] According to some embodiments of the present invention, the raw materials for preparing the white material further include at least one of the first auxiliary foaming agent and the second auxiliary foaming agent, and the white material premixing process further includes: mixing at least one of A to C with the raw materials for the nucleating aid to form a third mixture, and mixing the first mixture, the second mixture and the third mixture to obtain the white material: A: part or all of the first auxiliary foaming agent; B: part or all of the second auxiliary foaming agent; C: part of the LBA (see the "remaining part of the LBA" in the above embodiments for the example dosage). Among them, when there is a first auxiliary foaming agent that is not mixed with the nucleating aid, this first auxiliary foaming agent is used to mix with the raw materials for the first mixture; when there is a second auxiliary foaming agent that is not mixed with the nucleating aid, this second auxiliary foaming agent is used to mix with the raw materials for the second mixture; the LBA that is not mixed with the nucleating aid (see the "a part of the LBA" in the above embodiments for the example dosage) is used to mix with the raw materials for the second mixture.

[0042] According to some embodiments of the present invention, the mass ratio of the nucleating agent to the remaining part of the LBA ≥ 1:5.

[0043] According to some embodiments of the present invention, the mass ratio of the nucleating agent to the remaining part of the LBA ≥ 1:2.

[0044] According to some embodiments of the present invention, the nucleating agent is selected from perfluoroolefin compounds. Perfluoroolefin compounds have a low surface energy and relatively poor compatibility with components such as polyols. At the same time, their density is greater than that of the white material. Using the traditional white material premixing process, it is easy to cause the nucleating agent to settle, thereby losing its nucleating effect. Mixing the nucleating agent with the premixed first mixture and second mixture can prevent the nucleating agent from settling during long-term residence in long pipelines and storage tanks. Moreover, by utilizing the material disturbance (stirring or the action of the nozzle injection pressure) during the subsequent foaming process, the settlement of the nucleating agent can also be inhibited.

[0045] According to some embodiments of the present invention, the nucleating agent is selected from C 3 -C 8 perfluoroolefin compounds or mixtures thereof. For example, specifically selected from hexafluoropropene, perfluoro(4-methyl-2-pentene), perfluoro(2-methyl-2-pentene), hexafluorobutadiene or mixtures thereof. The commercially available grades include PF-5056, FA-188, PF-90, etc.

[0046] According to some embodiments of the present invention, the mass of the nucleating agent is 0-6% of the mass of the polyol.

[0047] According to some embodiments of the present invention, the mass of the nucleating agent is 0-4% of the mass of the polyol.

[0048] Nucleating agents generally have a high cost. Under the condition of ensuring that the foam properties meet the requirements, the dosage of the nucleating agent should be as low as possible or not added.

[0049] According to some embodiments of the present invention, the raw materials for preparing the white material further include an organometallic catalyst. The step of forming the first mixture includes: mixing the raw materials including a part of the polyol, a part of the surfactant, the organic amine catalyst, and the organometallic catalyst to form a first mixture.

[0050] According to some embodiments of the present invention, the organometallic catalyst is selected from one or two of organotin catalysts and organobismuth catalysts.

[0051] Organometallic catalysts play an important role in promoting the rapid gel reaction of the black material and the white material and promoting the establishment of viscosity. Among them, organotin catalysts, such as dibutyltin dilaurate, etc.; organobismuth catalysts, such as one or a combination of bismuth isooctanoate, bismuth laurate, bismuth neodecanoate, bismuth naphthenate, bismuth oxide, bismuth nitrate, etc.

[0052] According to some embodiments of the present invention, the mass of the organometallic catalyst is 0 to 1% of the mass of the polyol.

[0053] According to some embodiments of the present invention, the polyol is selected from one or two of polyether polyol or polyester polyol.

[0054] According to some embodiments of the present invention, the average hydroxyl value of the polyol is 350 to 450 mgKOH / g, and the average functionality is 4.5 to 6.5.

[0055] According to some embodiments of the present invention, in the process of forming the first mixture, a part of the polyol accounts for 5% to 35% of the mass percentage of the polyol.

[0056] To form a delicate and uniform cell structure, polyols with high functionality and high hydroxyl value are usually used, which usually have a certain viscosity. Therefore, the polyol content in the first mixture should not be too high to ensure transportability and reduce the temperature control energy consumption during operation throughout the year (especially in winter).

[0057] It should be noted that the types and proportions of the polyols in the first mixture and the second mixture can be the same or different. When LBA is added as a single physical blowing agent, the polyols in the two can be the same. When a further physical blowing agent is added, for example, a pentane-based auxiliary blowing agent is added to the first mixture, the types and proportions of the polyols in the two can be different.

[0058] According to some embodiments of the present invention, the polyol is selected from a combination of polyether polyol and polyester polyol.

[0059] According to some embodiments of the present invention, the mass percentage of the polyester polyol in the polyol is ≤15%, for example, it can be 5% to 15%.

[0060] As an example, the polyether polyol is selected from sucrose-initiated polyether polyol, toluenediamine-initiated polyether polyol, sorbitol-initiated polyether polyol, etc.; the polyester polyol is selected from phthalic anhydride-based polyester polyol, etc. In actual use, different polyol combinations can be selected according to the required thermal conductivity and foam material properties. One feasible way is to adjust the hydroxyl value and functionality within the ranges exemplified above by combining different polyols.

[0061] As an example, three combinations of sucrose-initiated polyether polyol, toluenediamine-initiated polyether polyol, and sorbitol-initiated polyether polyol, or four combinations of sucrose-initiated polyether polyol, toluenediamine-initiated polyether polyol, phthalic anhydride-based polyester polyol, and sorbitol-initiated polyether polyol are adopted. For example, when the above four polyol combinations are used, the raw material selection is as follows: sucrose-initiated polyether polyol, functionality 6-7, hydroxyl value 425±15mgKOH / g, viscosity 32000±4000mPa·s; toluenediamine-initiated polyether polyol, functionality 4, hydroxyl value 400±15mgKOH / g, viscosity 12000±1500mPa·s; phthalic anhydride-based polyester polyol, functionality 2, hydroxyl value 405±15mgKOH / g, viscosity 1100±100mPa·S; sorbitol-initiated polyether polyol, functionality 5-6, hydroxyl value 540±25mgKOH / g, viscosity 22000±3000mPa·S. The raw material ratio is, for example, by mass ratio, the mass ratio of sucrose-initiated polyether polyol: toluenediamine-initiated polyether polyol: phthalic anhydride-based polyester polyol: sorbitol-initiated polyether polyol is (15-30):(40-60):(5-15):(15-30), and at the same time, the mass percentage of phthalic anhydride-based polyester polyol in the polyols does not exceed 15%. Based on the above component combination, a combined polyol with an average hydroxyl value of (400±50)mgKOH / g and an average functionality of 5±0.5 can be obtained.

[0062] It should be noted that when a pentane such as cyclopentane is added as an auxiliary foaming agent, due to the poor compatibility of sucrose-initiated polyether polyol, phthalic anhydride-based polyester polyol, and sorbitol-initiated polyether polyol with cyclopentane (less than 6 parts by mass of cyclopentane can be dissolved per 100 parts by mass), while the compatibility of toluenediamine-initiated polyether polyol with cyclopentane is very good (more than 80 parts by mass of cyclopentane can be dissolved per 100 parts by mass). At this time, the mass ratio of toluenediamine-initiated polyether polyol 2 in the polyols can be controlled at 50-60%.

[0063] According to some embodiments of the present invention, the surfactant is selected from silicone surfactants, and the optional grades include: one of Evonik Chemistry B-8481, Evonik Chemistry B-84813, Evonik Chemistry EP-R-S 88, Evonik Chemistry MG-828, Evonik Chemistry MG-945, etc.

[0064] The functions of the surfactant mainly include three aspects: emulsification, nucleation, and foam stabilization. Due to the slight differences in their structures, each surfactant can be classified as a nucleating surfactant (with a relatively high unit price), a surfactant with strong emulsifying and foam stabilizing abilities, or a comprehensive surfactant (with high cost performance). In the actual white material formulation, a single type of surfactant can be used according to the performance and cost targets to be achieved, or two or more surfactants can be used in combination.

[0065] According to some embodiments of the present invention, the mass of the surfactant is 2% - 6% of the mass of the polyol.

[0066] According to some embodiments of the present invention, the mass ratio of a part of the surfactant to the remaining part thereof is 1 - 3:1, and the types of the two surfactants can be the same or different.

[0067] According to some embodiments of the present invention, the viscosities of the first mixture and the second mixture respectively satisfy: the viscosity at 25°C ≤ 1000 mPa·s. The viscosity condition is a necessary condition to ensure that the electrical appliance OEMs such as refrigerators and freezers can transport the white material to the production line foaming platform. If the material viscosity is too high, affected by temperature changes, during the transportation process (the transportation distance is often > 500 m), the pipeline must be heated or insulated, which will inevitably increase the energy consumption and control difficulty of the factory. Therefore, by splitting and premixing the components and ensuring the viscosity of the material, the reliability of the foaming system during the four seasons (especially in winter) is increased, and the system temperature control energy consumption is significantly reduced.

[0068] The second aspect of the present invention relates to a white material premixing system for premixing a white material whose preparation raw materials include polyol, surfactant, organic amine catalyst, LBA, and water. The white material premixing system includes: a first white material premixing device, a second white material premixing device, and a third white material premixing device; the first white material premixing device is configured to transport the preparation raw materials including a part of the polyol, a part of the surfactant, and the organic amine catalyst to the third white material premixing device; the second white material premixing device is configured to mix the preparation raw materials including the remaining part of the polyol, the remaining part of the surfactant, the LBA, and the water and transport them to the third white material mixing device; the third white material premixing device is simultaneously connected to the first white material premixing device and the second white material premixing device.

[0069] The white material premixing system of this embodiment can be used to implement the above-mentioned white material premixing process. Therefore, it has at least all the beneficial effects of the above-mentioned embodiments of the white material premixing process. Furthermore, by using this white material premixing system for white material premixing, the foaming stability and reliability of the white material can be improved.

[0070] According to some embodiments of the present invention, the raw materials for preparing the white material further include a nucleating aid, and the white material premixing system further includes: a nucleating aid premixing device communicated with the third white material premixing device, and the nucleating aid premixing device is configured to transport the raw materials including the nucleating aid to the third white material premixing device.

[0071] According to some embodiments of the present invention, the second white material premixing device is configured to mix the remaining part of the polyol, the remaining part of the surfactant, a part of the LBA, and the raw materials of the water, and transport them to the third white material mixing device; the nucleating aid premixing device is configured to mix the raw materials including the nucleating aid and the remaining part of the LBA, and transport them to the third white material premixing device.

[0072] According to some embodiments of the present invention, the raw materials for preparing the white material further include at least one of a first auxiliary foaming agent and a second auxiliary foaming agent, and the nucleating aid premixing device is further configured to mix the raw materials including at least one of A to C and the nucleating aid, and transport them to the third white material premixing device: A: part or all of the first auxiliary foaming agent; B: part or all of the second auxiliary foaming agent; C: part of the LBA. Wherein, when there is a first auxiliary foaming agent that is not mixed with the nucleating aid, the first auxiliary foaming agent is configured to be mixed with the raw materials in the first white material premixing device; when there is a second auxiliary foaming agent that is not mixed with the nucleating aid, the second auxiliary foaming agent is configured to be mixed with the raw materials in the second white material premixing device; the LBA that is not mixed with the nucleating aid is configured to be mixed with the raw materials in the second white material premixing device.

[0073] It can be understood that the above white material premixing system can be used to implement the above white material premixing process. Therefore, for specific examples of raw material selection or ratio, refer to the relevant embodiments of the foregoing white material premixing process.

[0074] According to some embodiments of the present invention, the first white material premixing device includes a first static mixer.

[0075] According to some embodiments of the present invention, the second white material premixing device includes a second static mixer.

[0076] According to some embodiments of the present invention, the third white material premixing device includes a third static mixer.

[0077] Among them, the static mixer includes a tubular static mixer.

[0078] According to some embodiments of the present invention, a first liquid storage tank communicated with both of them is provided between the first white material premixing device and the third white material premixing device.

[0079] According to some embodiments of the present invention, a second liquid storage tank communicating with both is provided between the second white material premixing device and the third white material premixing device.

[0080] The third aspect embodiment of the present invention relates to a polyurethane foaming system, including the above-mentioned white material premixing system, a white material working tank, a black material working tank, and a foaming machine; the third white material mixing device of the white material premixing system is communicated with the white material working tank, and the foaming machine is simultaneously communicated with the white material working tank and the black material working tank.

[0081] In view of the fact that this white material premixing system can improve the stability and reliability of the mixed white material, and further, improve the reliability of the polyurethane foaming system equipped with this white material premixing system, it can improve the quality of the foamed product and reduce the production cost.

[0082] According to some embodiments of the present invention, a temperature control storage tank is provided between the third white material mixing device and the white material working tank. The temperature control storage tank is used to pre-control the temperature of the white material, so that no additional temperature control is required during the subsequent foaming process, which is convenient for realizing a rapid foaming process.

[0083] According to some embodiments of the present invention, the foaming machine includes a gun head. The material to be foamed is sprayed into the foaming cavity through the gun head and foamed into a foam material. The gun head pressure can be controlled at 100-150 bar, for example, 120-130 bar.

[0084] The fourth aspect embodiment of the present invention relates to a polyurethane foaming method, including: mixing the black material with the white material obtained by the above-mentioned white material premixing process and foaming to obtain a polyurethane foaming material.

[0085] The polyurethane foaming method of the embodiment of the present invention uses the white material prepared by the above-mentioned white material premixing process as the raw material. Therefore, it has at least all the beneficial effects of the embodiments of the above-mentioned white material premixing process. Further, this foaming method can improve the quality of the foamed product and reduce the production cost.

[0086] According to some embodiments of the present invention, the black material is polymethylene polyphenyl isocyanate, abbreviated as polymeric MDI, PAPI, crude MDI or PMDI. Its typical parameters, for example, the mass fraction of isocyanate group is 30-33 wt%, the viscosity at 25 °C is 150-250 mPa·s, the average functionality is 2.6-2.7, and the optional grades include Wanhua Chemical PM-200, PM-2010, Covestro 44V20, Dow Chemical PAPI27, PAPI135, BASF M20s, etc.

[0087] According to some embodiments of the present invention, before foaming, the temperature of the black material or the white material is 10-30°C. The boiling point of LBA is 19°C. If the material temperature exceeds its boiling point, the volatilization loss of LBA during the foaming process is relatively large. If the material temperature is too low, the reaction activity of the black material and the white material is relatively low. Specifically, the material temperatures of the two can be controlled at 15-17°C. In addition, pre-constanting the black material and the white material at the target temperature and then mixing them can improve production efficiency.

[0088] According to some embodiments of the present invention, the mass ratio of the black material to the white material is 0.9-1.5:1, for example, 1.0-1.1:1, which is determined according to the specific formula. The material ratio of the black material / white material is often closely related to the hydroxyl value of the polyol and the dosage of the chemical foaming agent water. If the material ratio is too low, the polyol reaction is insufficient and the foam strength is relatively low. If the material ratio is too high, the trimerization reaction of the isocyanate group in the black material is more, and the foam rigidity is stronger.

[0089] According to some embodiments of the present invention, the gun head pressure during foaming is 100-150 bar, for example, 120-130 bar. The gun head pressure often affects the mixing effect of the black material and the white material at the gun head. Generally, the greater the gun head pressure, the smaller the particle size after atomization of the black material and the white material, and the better the mixing effect. However, if the gun head pressure is too high (such as exceeding 150 bar), it will affect the long-term service life of the high-pressure foaming machine, thereby increasing the operation and maintenance cost of the production line.

[0090] The fifth aspect embodiment of the present invention also relates to the application of the above-mentioned white material premixing process, white material premixing system, polyurethane foaming system or polyurethane foaming method in the preparation of household appliances.

[0091] In view of the advantages of the above-mentioned white material premixing process, the quality of the foamed product is improved and the production cost is reduced. Furthermore, the energy consumption and production cost of household appliances applying this premixing process can be reduced.

[0092] According to some embodiments of the present invention, the household appliances include refrigerators, freezers, water heaters, air conditioners or heat pumps.

[0093] In this article, "a variety of" means two or more; when referring to a numerical range, it includes the end values and any subset range within this range.

[0094] The expression "mixing the preparation raw materials including..." includes both the way of mixing all the preparation raw materials at one step and the way of step-by-step mixing. For example, "mixing the preparation raw materials including the remaining part of the polyol, the remaining part of the surfactant, the LBA and the water" can either be mixing all the preparation raw materials at one step or pre-mixing the preparation raw materials including the remaining part of the polyol, the remaining part of the surfactant and the water first, and then mixing the obtained mixture with the preparation raw materials including the LBA. In practical applications, step-by-step mixing may be more suitable for actual foaming production lines. Usually, the raw material supplier pre-mixes the components other than the volatile physical foaming agents (such as LBA, the above-mentioned auxiliary foaming agents), and then adds the physical foaming agent for mixing on the foaming production line. This way can improve the foaming efficiency and reduce the equipment investment of the foaming production line.

[0095] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. Description of the Drawings

[0096] Figure 1 is a flowchart of the polyurethane foaming method of Embodiment 1 of the present invention.

[0097] Figure 2 is a schematic diagram of the heat conduction mechanism of the foam material.

[0098] Figure 3 is a schematic structural diagram of the polyurethane foaming system of Embodiment 10 of the present invention.

[0099] Reference Signs:

[0100] White Material Premixing System 100, First White Material Premixing Device 110, Second White Material Premixing Device 120, Third White Material Premixing Device 130, Nucleating Agent Premixing Device 140, Liquid Storage Tank 150;

[0101] White Material Working Tank 200, Black Material Working Tank 300, Foaming Machine 400, Household Appliance 500. Detailed Description of the Embodiments

[0102] The embodiments of the present invention will be described in detail below. The embodiments are exemplary and are only used to explain the present invention and should not be construed as a limitation to the present invention.

[0103] In the following embodiments, the relevant raw materials are described as follows:

[0104] Polyol: Sucrose-initiated polyether polyol, Ningwu New Materials, NJ-8238; Sorbitol-initiated polyether polyol, Yinuowei, R6048; Toluenediamine-initiated polyether polyol, Hebei Yadong, YD-402P; Phthalic anhydride polyester polyol, Stepan, PS-3152.

[0105] Surfactant: Evonik Chemistry B-84813.

[0106] Organometallic catalyst: Dibutyltin dilaurate.

[0107] Nucleating agent: 3M Company, PF-5056, perfluoroolefin mixture.

[0108] LBA: Honeywell.

[0109] Black material: Wanhua PM-2010.

[0110] Example 1

[0111] See Figure 1 , this example provides a white material premixing process, including:

[0112] S100. Provide mixture A including 20.0 parts of polyol (4.0 parts of sucrose-initiated polyether polyol, 4.0 parts of sorbitol-initiated polyether polyol, 12.0 parts of toluenediamine-initiated polyether polyol), 2.5 parts of surfactant, 4.5 parts of organic amine catalyst (0.5 part of pentamethyldiethylenetriamine, 3.0 parts of N,N-dimethylcyclohexylamine, 1.0 part of tris(dimethylaminopropyl)hexahydrotriazine), and 0.1 part of organometallic catalyst; provide mixture B including 80.0 parts of polyol (20.0 parts of sucrose-initiated polyether polyol, 14.0 parts of sorbitol-initiated polyether polyol, 40.0 parts of toluenediamine-initiated polyether polyol, 6.0 parts of phthalic anhydride polyester polyol), 2.0 parts of surfactant, and 1.9 parts of water.

[0113] S200. Add 6.0 parts of cyclopentane to 27.1 parts of mixture A and mix to obtain POL1, with viscosities of: 6115 mPa·s at 0 °C and 417 mPa·s at 25 °C; add 28.0 parts of LBA main blowing agent and 1.2 parts of HFC-152a auxiliary blowing agent to 83.9 parts of mixture B and mix to obtain POL2, with viscosities of: 942 mPa·s at 0 °C and 185 mPa·s at 25 °C; premix 2.0 parts of LBA and 2.0 parts of nucleating agent (abbreviation PF) to obtain LBA / PF composition.

[0114] S300. Premix POL1, POL2, and LBA / PF composition in a mass ratio of 33.1:113.1:4.0 to obtain white material.

[0115] In step S200, through component splitting and premixing, and by ensuring the viscosity of the material, the reliability of the foaming system during operation throughout the four seasons (especially in winter) is increased, and the temperature control energy consumption of the system is significantly reduced. Controlling the viscosity condition is a necessary condition to ensure that the main appliance factories such as refrigerators and freezers can transport the white material to the foaming platform of the production line. Taking the Jingzhou factory of Midea refrigerators or freezers as an example, the temperature changes greatly throughout the four seasons. For example, the lowest temperature in winter can reach -5°C, and the highest temperature in summer can reach 35°C. If the material viscosity is too high, affected by temperature changes, during the transportation process (the transportation distance is often >500m), it is necessary to heat or insulate the pipeline, which will inevitably increase the energy consumption and management difficulty of the factory.

[0116] See Figure 1 , this embodiment also provides a polyurethane foaming method, including:

[0117] S400. Mix the white material and the black material in step S300, and perform foaming under different process parameter conditions (see Table 2 below) to obtain polyurethane foam.

[0118] Example 2

[0119] This embodiment provides a white material premixing process, including:

[0120] S100. Provide a mixture A, denoted as POL1, including 10.0 parts of polyol (2.4 parts of sucrose-initiated polyether polyol, 1.8 parts of sorbitol-initiated polyether polyol, 5.2 parts of toluenediamine-initiated polyether polyol, 0.6 part of phthalic anhydride polyester polyol), 3.0 parts of surfactant, 4.5 parts of organic amine catalyst (0.5 part of pentamethyldiethylenetriamine, 3.0 parts of N,N-dimethylcyclohexylamine, 1.0 part of tris(dimethylaminopropyl)hexahydrotriazine), and 0.1 part of organic metal catalyst; the viscosity is: 4100 mPa·s at 0°C and 302 mPa·s at 25°C. Provide a mixture B including 90.0 parts of polyol (21.6 parts of sucrose-initiated polyether polyol, 16.2 parts of sorbitol-initiated polyether polyol, 46.8 parts of toluenediamine-initiated polyether polyol, 5.4 parts of phthalic anhydride polyester polyol), 2.0 parts of surfactant, and 1.9 parts of water.

[0121] S200. Add 36.0 parts of LBA main foaming agent to 93.9 parts of mixture B to obtain POL2; the viscosity is: 850 mPa·s at 0°C and 162 mPa·s at 25°C. Premix 2.0 parts of LBA and 2.0 parts of nucleating aid (abbreviation: PF) to obtain the LBA / PF composition.

[0122] S300. Premix POL1, POL2, and the LBA / PF composition according to the mass ratio of 17.6:129.9:4.0 to obtain the white material.

[0123] This embodiment also provides a method for polyurethane foaming, including:

[0124] Mix the white material and the black material in step S300, and foam under different process parameter conditions (see Table 3 below) to obtain polyurethane foam.

[0125] Example 3

[0126] This embodiment provides a white material premixing process, including:

[0127] S100. Provide mixture A (POL1) including 10.0 parts of polyol (2.0 parts of sucrose-initiated polyether polyol, 1.8 parts of sorbitol-initiated polyether polyol, 5.2 parts of toluenediamine-initiated polyether polyol, 1.0 part of phthalic anhydride polyester polyol), 3.0 parts of surfactant, 4.0 parts of organic amine catalyst (0.4 part of pentamethyldiethylenetriamine, 3.0 parts of N,N-dimethylcyclohexylamine, 0.6 part of tris(dimethylaminopropyl)hexahydrotriazine), and 0.1 part of organometallic catalyst; provide mixture B including 90.0 parts of polyol (18.0 parts of sucrose-initiated polyether polyol, 16.2 parts of sorbitol-initiated polyether polyol, 46.8 parts of toluenediamine-initiated polyether polyol, 9.0 parts of phthalic anhydride polyester polyol), 2.0 parts of surfactant, and 1.5 parts of water;

[0128] S200. Add 39.0 parts of LBA main blowing agent to mixture B to obtain POL2; premix 3.0 parts of LBA and 3.0 parts of nucleating agent (abbreviation: PF) to obtain LBA / PF composition;

[0129] S300. Premix POL1, POL2, and LBA / PF composition to obtain white material.

[0130] This embodiment also provides a method for polyurethane foaming, including:

[0131] Mix the white material in step S300 with the black material and foam to obtain polyurethane foam.

[0132] Example 4

[0133] This embodiment provides a white material premixing process, including:

[0134] S100. Provide mixture A, denoted as POL1, which includes 10.0 parts of polyol (2.0 parts of sucrose-initiated polyether polyol, 1.8 parts of sorbitol-initiated polyether polyol, 5.2 parts of toluenediamine-initiated polyether polyol, and 1.0 part of phthalic anhydride polyester polyol), 3.0 parts of surfactant, 4.0 parts of organic amine catalyst (0.4 part of pentamethyldiethylenetriamine, 3.0 parts of N,N-dimethylcyclohexylamine, and 0.6 part of tris(dimethylaminopropyl)hexahydrotriazine), and 0.1 part of organometallic catalyst; provide mixture B which includes 90.0 parts of polyol (18 parts of sucrose-initiated polyether polyol, 16.2 parts of sorbitol-initiated polyether polyol, 46.8 parts of toluenediamine-initiated polyether polyol, and 9 parts of phthalic anhydride polyester polyol), 2.0 parts of surfactant, and 1.5 parts of water.

[0135] S200. Add 35.0 parts of LBA main foaming agent and 1.5 parts of HFC-152a auxiliary foaming agent to mixture B and mix to obtain POL2; premix 3.0 parts of LBA and 3.0 parts of nucleating agent (abbreviation: PF) to obtain LBA / PF composition.

[0136] S300. Premix POL1, POL2, and LBA / PF composition to obtain the white material.

[0137] This embodiment also provides a polyurethane foaming method, including:

[0138] Mix the white material in step S300 with the black material for foaming to obtain polyurethane foam.

[0139] Example 5

[0140] This embodiment provides a white material premixing process, including:

[0141] S100. Provide mixture A, denoted as POL1, which includes 10.0 parts of polyol (2.4 parts of sucrose-initiated polyether polyol, 1.8 parts of sorbitol-initiated polyether polyol, 5.2 parts of toluenediamine-initiated polyether polyol, and 0.6 part of phthalic anhydride polyester polyol), 3.0 parts of surfactant, 4.0 parts of organic amine catalyst (0.4 part of pentamethyldiethylenetriamine, 3.0 parts of N,N-dimethylcyclohexylamine, and 0.6 part of tris(dimethylaminopropyl)hexahydrotriazine), and 0.1 part of organometallic catalyst; provide mixture B which includes 90.0 parts of polyol (18.0 parts of sucrose-initiated polyether polyol, 16.2 parts of sorbitol-initiated polyether polyol, 46.8 parts of toluenediamine-initiated polyether polyol, and 9.0 parts of phthalic anhydride polyester polyol), 2.0 parts of surfactant, and 2.1 parts of water.

[0142] S200. Add 35.0 parts of LBA main foaming agent to mixture B and mix to obtain POL2.

[0143] S300. Premix POL1 and POL2 to obtain the white material.

[0144] This embodiment also provides a polyurethane foaming method, including:

[0145] Mix the white material obtained in step S300 with the black material and carry out foaming to obtain polyurethane foam.

[0146] Example 6

[0147] This embodiment provides a white material premixing process, including:

[0148] S100. Provide mixture A including 20.0 parts of polyol (4.0 parts of sucrose-initiated polyether polyol, 4.0 parts of sorbitol-initiated polyether polyol, 12.0 parts of toluenediamine-initiated polyether polyol), 3.5 parts of surfactant, 4.3 parts of organic amine catalyst (0.4 part of pentamethyldiethylenetriamine, 3.0 parts of N,N-dimethylcyclohexylamine, 0.9 part of tris(dimethylaminopropyl)hexahydrotriazine), and 0.1 part of organometallic catalyst; provide mixture B including 80.0 parts of polyol (20.0 parts of sucrose-initiated polyether polyol, 14.0 parts of sorbitol-initiated polyether polyol, 40.0 parts of toluenediamine-initiated polyether polyol, 6.0 parts of phthalic anhydride polyester polyol), 1.0 part of surfactant, and 1.8 parts of water.

[0149] S200. Add 7.0 parts of cyclopentane to mixture A and mix to obtain POL1; add 26.0 parts of LBA main blowing agent and 1.0 part of HFC-152a auxiliary blowing agent to mixture B and mix to obtain POL2; premix 2.0 parts of LBA and 2.0 parts of nucleating agent (abbreviation: PF) to obtain the LBA / PF composition.

[0150] S300. Premix POL1, POL2, and the LBA / PF composition to obtain the white material.

[0151] This embodiment also provides a polyurethane foaming method, including:

[0152] Mix the white material obtained in step S300 with the black material and carry out foaming to obtain polyurethane foam.

[0153] Example 7

[0154] This embodiment provides a white material premixing process, including:

[0155] S100. Provide mixture A including 20.0 parts of polyol (4.0 parts of sucrose-initiated polyether polyol, 4.0 parts of sorbitol-initiated polyether polyol; 12.0 parts of toluene diamine-initiated polyether polyol), 3.5 parts of surfactant, 4.3 parts of organic amine catalyst (0.4 part of pentamethyldiethylenetriamine, 3.0 parts of N,N-dimethylcyclohexylamine, 0.9 part of tris(dimethylaminopropyl)hexahydrotriazine), and 0.1 part of organometallic catalyst; provide mixture B including 80.0 parts of polyol (20.0 parts of sucrose-initiated polyether polyol, 14.0 parts of sorbitol-initiated polyether polyol, 40.0 parts of toluene diamine-initiated polyether polyol; 6.0 parts of phthalic anhydride polyester polyol), 1.0 part of surfactant, and 2.2 parts of water.

[0156] S200. Add 7.0 parts of cyclopentane to mixture A and mix to obtain POL1; add 22.0 parts of LBA main blowing agent to mixture B and mix to obtain POL2.

[0157] S300. Premix POL1 and POL2 to obtain the white material.

[0158] This embodiment also provides a polyurethane foaming method, including:

[0159] Mix the white material in step S300 with the black material and foam to obtain polyurethane foam.

[0160] The component ratios and foaming process parameters of Examples 3-7 are shown in Table 1 below:

[0161] Table 1 Component ratios, foaming process parameters and foam thermal conductivity of Examples 3-7

[0162]

[0163] Example 8

[0164] Refer to Example 2 (the foaming process parameters are the same as those of Example 2-1), the difference is that: step S200 does not include the step of preparing the LBA / PF composition, and thus in step S300, the LBA / PF composition is not added, and the rest remains unchanged.

[0165] Example 9

[0166] Compared with Example 2 (the foaming process parameters are the same as those of Example 2-1), the difference is that steps S200 and S300 are as follows:

[0167] S200. Add 38.0 parts of LBA main blowing agent to 93.9 parts of mixture B to obtain POL2.

[0168] S300. Premix POL1 and POL2 according to the mass ratio of 17.6:131.9 to obtain the white material.

[0169] Comparative Example 1

[0170] Compared with Example 2, the difference is that 3.0 parts of surfactant in mixture A are added to mixture B, that is, there is no surfactant in mixture A and 5.0 parts of surfactant are contained in mixture B, and the rest remains unchanged.

[0171] Test Example

[0172] 1. Compressive strength: The test is carried out in accordance with GB / T 26689-2011 "Rigid polyurethane foam plastics for refrigerators and freezers". The specimen size is (50±1) mm×(50±1) mm×(30±1) mm, the test speed is (5±1) mm / min, loads are applied to the specimen in three directions respectively, the number of specimens in each direction is 3, the average value of 3 test data in each direction is taken, and the minimum value among the 3 average values is taken as the result. At present, the national standard requirement for the compressive strength of rigid polyurethane foam for refrigerators / freezers is ≥120 kPa.

[0173] 2. Thermal conductivity: The foamed sample is cut into a peeled foam with a size of (200±5) mm×(200±5) mm and a thickness of (25±1) mm by a cutting machine. The cold plate temperature of the thermal conductivity meter is 2°C and the hot plate temperature is 18°C. Considering the temperature fluctuation, the temperature difference between the cold and hot plates does not exceed 18°C, the average temperature is 10°C, 2 samples are taken, and the result is the average value.

[0174] 3. Density: The specimen size is (50±1) mm×(50±1) mm×(50±1) mm, and the density is measured by the water displacement method. The number of specimens is 3, and the result is the average value.

[0175] 4. Number of surface air pit defects: The inner liner of the refrigerator after foaming is disassembled, and the number of air pit defects with a diameter >3 cm on the outer surface of the foam part is calculated.

[0176] Table 2 and Table 3 show the partial foam properties of Example 1 and Example 2 under different foaming process parameters respectively.

[0177] Table 2 Foaming Process and Foam Properties of Example 1

[0178]

[0179]

[0180] Table 3 Foaming Process and Foam Properties of Example 2

[0181]

[0182] It can be seen that the foaming process affects various properties of the foam, and according to different formulations, the applicable optimal process conditions may vary. For products such as refrigerators, water heaters, and heat pumps, the main function of applying polyurethane foam is heat insulation. Therefore, the thermal conductivity is one of the key performance indicators of the foam; at the same time, for products, especially refrigerator products, the filled polyurethane foam also plays a structural load-bearing role, and there are also requirements for its mechanical properties. Overall, the thermal conductivity of each embodiment is below 17 mW / m·K, obtaining a lower thermal conductivity and having good mechanical properties (the foam compression strength of most embodiments meets the usage requirements of refrigerators).

[0183] Referring to the thermal conductivity of the foams prepared in Examples 3-7 in Table 1, it can be seen that the premixing process of the examples has strong adaptability, is applicable to both the formulation using only LBA as a single physical blowing agent and the formulation containing other auxiliary physical blowing agents, which is beneficial to the development of a series of low-thermal-conductivity formulations with high cost performance and excellent stability.

[0184] The characteristic parameters of the physical blowing agent and nucleating aid involved in this embodiment are shown in Table 4. Although the gas-phase thermal conductivity of LBA is low, its molecular weight is large (more blowing agent parts are required to achieve the same foam density), especially when used as a single physical blowing agent, the application cost is high, and it is only applicable to some high-end and ultra-energy-saving products. In contrast, the auxiliary blowing agent cyclopentane has a low molecular weight and unit price, and the application cost is low. HFC-152a has a low boiling point, and after application, it can significantly reduce the foam density and improve the foam strength, which is beneficial to reducing the comprehensive cost. The nucleating aid plays a significant role in foam nucleation, can effectively reduce the thermal conductivity of the foam, but its cost is high.

[0185] Table 4 Characteristic parameters of physical blowing agents and nucleating aids in the examples

[0186]

[0187] In Table 1, there are an ultra-low thermal conductivity formulation using a single LBA (Example 3), a cost-effective ultra-low thermal conductivity formulation with a reduced cost by replacing part of the LBA with 152a (Example 4), a cost-effective low thermal conductivity formulation that reduces the LBA dosage by increasing the amount of chemical blowing agent water without using a nucleating agent (Example 5), and a cost-effective low thermal conductivity formulation using a ternary physical blowing agent of LBA, 152a, and cyclopentane (Example 6), and a cost-effective low thermal conductivity formulation that reduces the LBA dosage by increasing the chemical blowing agent water without using the nucleating agent PF (Example 7). Among them, although Examples 3 and 4 have higher application costs, the thermal conductivity of the foam is significantly reduced, which is particularly suitable for high-end products and super energy-saving products, can replace or partially replace the expensive vacuum insulation panel (VIP) used in the product, and can reduce the comprehensive cost of the product. Example 5 does not use expensive nucleating agents and has a relatively higher cost performance, which is particularly suitable for products with higher energy consumption requirements or products that need to improve energy consumption; Examples 6 and 7 have relatively higher cost performance, and the thermal conductivity of the foam is also reduced compared with the existing mass-produced foam, which is particularly suitable for products that are more sensitive to costs.

[0188] Refer to Table 5, which shows partial foam properties and foaming process parameters of Example 2 (2-1), Example 8, and Example 9 of this application. Example 8 simulates the situation where the LBA / PF composition is not added due to a production line failure. From the results, compared with Example 2, the thermal conductivity and density of the foam both show obvious abnormal increases. Therefore, once the production line monitors that the above two indicators simultaneously show abnormalities, the cause of the abnormality can be quickly identified and rectified. It should be noted that in actual production, abnormalities can be detected by monitoring the foam density. Since the addition of the LBA / PF composition is missed, the amount of blowing agent is reduced, which will cause the foam density to become abnormally large. Furthermore, by monitoring the foam density (the foam density test is easier to implement with the production line. A sample can be detected by spraying a small amount of foaming material, without the need to modify the production line, and the detection is more convenient and the cost is lower), it can be checked whether there is an abnormality in the addition of the nucleating agent. If the nucleating agent is not diluted with LBA but directly mixed with POL1 and POL2 (the LBA originally used to dilute the nucleating agent is added to POL2 in equal amounts), when the nucleating agent is missed (Example 9), there is more LBA (not participating in the reaction) compared with Example 8. Under the condition that other raw materials and foaming process conditions remain unchanged, it is equivalent to a certain degree of dilution of the catalyst and reactant concentrations, and the reaction rate will slow down to a certain extent. Therefore, the cell size of Example 9 will be larger than that of Example 8. As Figure 2 shown (the circles in the figure represent the cells, and the arrowed lines indicate the heat transfer path), the smaller the cell size, the longer the heat transfer path in the solid phase part, the slower the heat will be transferred, and the lower the thermal conductivity. Therefore, the increase in cell size causing the shortening of the heat transfer path may be the main reason for the deterioration of the thermal conductivity in Example 9.

[0189] Table 5 Foam properties and foaming process parameters of Example 2 (2-1), Example 8 and Example 9

[0190]

[0191] In addition, since the addition amount of the nucleating aid is small and the price is expensive, if it is directly added, it is easy to bring about metering errors, and once it is missed, it will also have an adverse effect on the thermal conductivity of the final foam. Based on the above considerations, a certain amount of LBA is pre-mixed with the nucleating aid to obtain an LBA / PF mixture, which can reduce metering errors. Therefore, by pre-mixing LBA and the nucleating aid, on the one hand, it can be used for rectifying the production process. That is, once the nucleating aid is missed and the thermal conductivity of the foam increases (which will cause abnormal energy consumption of products such as refrigerators / freezers), but because the total amount of the blowing agent also decreases, the density of the foam will also increase. Once the above abnormalities occur, it is conducive to quickly investigating the cause of the abnormality, ensuring the long-term stability and reliability of the production line process. On the other hand, it can reduce metering errors.

[0192] Table 6 shows some foam properties and foaming process parameters of Example 2 (2-1) and Comparative Example 1. It can be seen that by splitting and adding the polyol and the surfactant in the white material, the dispersion uniformity of each material is improved, and the foaming stability and surface quality can be improved. If the surfactant is not split and all is added to POL1, it will affect the uniformity of each component of POL2 without the surfactant; if all is added to POL2, it will affect the uniformity of each component of POL1 without the surfactant, especially the dispersion uniformity of the catalyst, and then will affect the mixing uniformity of the final white material and the foaming effect. For example, it will cause internal defects, skin defects, and foaming uniformity of the foam, and ultimately have an adverse effect on the heat preservation performance of the foam. In addition, the surface air pit defects of Comparative Example 1 increase significantly (the number of surface air pit defects increases by 60% compared with Example 2-1, and the sample surface area is the same, that is, the number of air pit defects per unit area increases by 60%), which will affect the bearing strength of electrical products (such as refrigerators) using this foam material as the insulation layer.

[0193] Table 6 Foam properties and foaming process parameters of Example 2 (2-1) and Comparative Example 1

[0194]

[0195] Example 10

[0196] See Figure 3 , this example provides a polyurethane foaming system, including a white material premixing system 100, a white material working tank 200, a black material working tank 300, and a foaming machine 400 that is simultaneously connected to the white material working tank 200 and the black material working tank 300.

[0197] The white material premixing system 100 includes: a first white material premixing device 110, a second white material premixing device 120, a nucleating agent premixing device 140, and a third white material premixing device 130, which are used to premix the white material of the preparation raw materials including polyol, surfactant, nucleating agent, organic amine catalyst, LBA, and water. The third white material premixing device 130 is simultaneously connected to the first white material premixing device 110, the second white material premixing device 120, the nucleating agent premixing device 140, and the white material working tank 200.

[0198] Among them, the first white material premixing device 110 is configured to convey the preparation raw materials including a part of polyol, a part of surfactant, and organic amine catalyst to the third white material premixing device 130. The second white material premixing device 120 is configured to mix the preparation raw materials including the remaining part of polyol, the remaining part of surfactant, a part of LBA, and water, and convey them to the third white material mixing device. The nucleating agent premixing device 140 is configured to mix the preparation raw materials including the nucleating agent and the remaining part of LBA, and convey them to the third white material premixing device 130.

[0199] It can be understood that the nucleating agent can also be directly added to the third white material premixing device 130 for mixing (such as ignoring the metering effect and the possible omission effect of the nucleating agent), and then the nucleating agent premixing device 140 is configured to convey the preparation raw materials including the nucleating agent to the third white material premixing device 130, that is, all LBA is mixed through the second white material premixing device 120.

[0200] In one embodiment, when the preparation raw materials of the white material further include a first auxiliary foaming agent, the first white material premixing device 110 is configured to mix the preparation raw materials including a part of polyol, a part of surfactant, organic amine catalyst, and the first auxiliary foaming agent, and convey them to the third white material premixing device 130.

[0201] In one embodiment, when the preparation raw materials of the white material further include a second auxiliary foaming agent, the second white material premixing device 120 is configured to mix the preparation raw materials including the remaining part of polyol, the remaining part of surfactant, a part of LBA (the whole of LBA when there is no need to dilute the nucleating agent with LBA), water, and the second auxiliary foaming agent, and convey them to the third white material premixing device 130.

[0202] It can be understood that when the raw materials for preparing the white material include the first auxiliary foaming agent and / or the second auxiliary foaming agent, the nucleating agent can also be diluted with the first auxiliary foaming agent and / or the second auxiliary foaming agent, or diluted with a mixture of at least two of LBA, the first auxiliary foaming agent, and the second auxiliary foaming agent. Furthermore, the nucleating agent premixing device 140 is configured to mix the nucleating agent with the physical foaming agent for dilution to form a third mixture. The physical foaming agent for dilution can be at least one of LBA, the first auxiliary foaming agent, or the second auxiliary foaming agent, and the dosage can be a part of LBA, a part or all of the first auxiliary foaming agent, or a part or all of the second auxiliary foaming agent. At this time, based on the total addition amount of each of LBA, the first auxiliary foaming agent, or the second auxiliary foaming agent, the LBA, the first auxiliary foaming agent, or the second auxiliary foaming agent that has been added in the nucleating agent premixing device 140 is correspondingly reduced in the feeding of the remaining devices.

[0203] It can be understood that the white material premixing system 100 of this embodiment can be used to implement the foregoing white material premixing process. Therefore, regarding the material composition or process parameters, reference can be made to the foregoing embodiments or examples.

[0204] In one embodiment, the first white material premixing device 110, the second white material premixing device 120, or the third white material premixing device 130 can adopt a commonly used tube-type static mixer in the art to achieve premixing of multiple materials.

[0205] Referring to the above Embodiments 1-8, it can be understood that when POL1 does not add an auxiliary foaming agent, POL1 can complete premixing in advance (for example, completed by an upstream supplier). At this time, the first white material premixing device 110 can be configured without a tube-type static mixer and a liquid storage tank 150, but to meter and convey POL1 to the third white material premixing device 130.

[0206] It can be understood that when the nucleating agent needs to be diluted, the nucleating agent premixing device 140 can also adopt a tube-type static mixer and be connected to the third white material premixing device 130 through a pipeline. When the nucleating agent does not need to be diluted, the tube-type static mixer is not provided in the nucleating agent premixing device 140, but it is configured to meter the nucleating agent and convey it to the third white material premixing device 130 for premixing. For a formulation that does not use a nucleating agent, the nucleating agent premixing device 140 can be omitted.

[0207] In one embodiment, a liquid storage tank 150 is provided between the first white material premixing device 110 and the third white material premixing device 130, and between the second white material premixing device 120 and the third white material premixing device 130. The liquid storage tank 150 is used to temporarily store materials, facilitating timely replenishment of materials. It can be understood that when the nucleating agent premixing device 140 premixes the nucleating agent and LBA, a liquid storage tank 150 can also be provided between the nucleating agent premixing device 140 and the third white material premixing device 130. The volume of the liquid storage tank 150 is, for example, 1 - 2m 3 .

[0208] In one embodiment, a temperature-controlled storage tank is provided between the third white material mixing device and the white material working tank 200. The temperature-controlled storage tank is used to pre-control the temperature of the white material, so that no additional temperature control is required during the subsequent foaming process, facilitating the realization of a rapid foaming process. Similarly, a temperature-controlled storage tank can also be provided between the conveying end of the black material and the black material working tank 300, so as to pre-control the temperature of the black material entering the black material working tank 300.

[0209] The foaming machine 400 includes a gun head. The material to be foamed is sprayed into the foaming cavity of a household appliance 500 (such as a refrigerator or a freezer) through the gun head, and foam material is formed through foaming as a heat-insulating layer. The gun head pressure can be controlled between 100 - 150 bar, for example, 120 - 130 bar.

[0210] Based on the problems of insufficient chemical stability of conventional catalysts (organic amine catalysts, organometallic catalysts) in a system with LBA as the main blowing agent, and the sedimentation stability of the nucleating agent during the storage and transportation of the foaming white material, this embodiment has carried out process optimization and adjustment. By specifically splitting and premixing the components in the white material, based on this multi-stage premixing method, the problem of poor stability of the white material existing in the existing process is solved, thereby improving the foaming quality, increasing the product yield, and reducing the production cost.

[0211] If the solution of this embodiment is not used, the chemical stability problem between LBA and the organic amine catalyst can be solved by using a high-cost organic amine catalyst with a lower reaction activity with LBA, but the catalyst cost increases by at least 100% compared with the existing conventional catalyst; or, the hydrolysis stability problem of ordinary organometallic catalysts can be partially solved by using a high-cost and strongly hydrolysis-resistant organometallic catalyst, but the hydrolysis rate of this kind of hydrolysis-resistant organometallic catalyst only slows down, and it does not mean that it does not hydrolyze, and its cost increases by at least 1000% compared with ordinary organometallic catalysts. If the solution of this embodiment is not used, when adding the nucleating agent, sedimentation is likely to occur in the traditional process, which will lead to a 3% - 5% increase in the thermal conductivity of the foam product, inevitably resulting in an increase in the energy consumption of the product using this foam product, and even the energy consumption not meeting the standard.

[0212] Based on the advantageous effects of the polyurethane foaming method or polyurethane foaming system of the present embodiment in improving the long-term stability of the white material, it can improve the quality of the foamed product and reduce the production cost, and further can reduce the energy consumption and production cost of household appliances using polyurethane foam as the thermal insulation layer. Among them, household appliances include refrigerators, freezers, water heaters, air conditioners or heat pumps, etc.

[0213] The present invention has been described in detail above in conjunction with the embodiments. However, the present invention is not limited to the above embodiments, and various changes can be made without departing from the gist of the present invention within the scope of knowledge possessed by those of ordinary skill in the art.

Claims

1. A white material premixing process, characterized in that: include: Providing preparation raw materials including polyols, surfactants, organic amine catalysts, LBA and water; Mixing a preparation material including a portion of the polyol, a portion of the surfactant, and the organic amine catalyst to form a first mixture; mixing a preparation feed including a remaining portion of the polyol, a remaining portion of the surfactant, the LBA, and the water to form a second mixture; The first mixture is mixed with the second mixture to obtain a white material.

2. The white material premixing process according to claim 1, characterized in that: The mass of the LBA is 10% to 50% of the mass of the polyol; and / or the mass of the water does not exceed 3% of the mass of the polyol; and / or the mass of the organic amine catalyst is 1% to 10% of the mass of the polyol.

3. The white material premixing process according to claim 1, characterized in that: The organic amine catalyst is selected from a combination of at least two of a foaming catalyst, a gel catalyst, and a trimerization catalyst, wherein the foaming catalyst is selected from one or two of pentamethyldiethylenetriamine and bis(dimethylaminoethyl) ether, the gel catalyst is selected from a combination of one or more of N,N-dihexylmethylamine, N,N-dimethylcyclohexylamine, and triethylenediamine, and the trimerization catalyst is selected from one or two of tris(dimethylaminopropyl)hexahydrotriazine and 2-hydroxypropyltrimethylammonium formate.

4. The white material premixing process according to claim 3, characterized in that: The mass of the foaming catalyst is 0-1% of the mass of the polyol; and / or, the mass of the gel catalyst is 2.5%-6% of the mass of the polyol; and / or, the mass of the trimerization catalyst is 0.6%-3% of the mass of the polyol.

5. The white material premixing process according to claim 1, characterized in that: The raw materials for preparing the white material also include a first auxiliary foaming agent, and the first auxiliary foaming agent is selected from one or a combination of pentane, 1,1-difluoroethane, 1,3,3,3-tetrafluoro-1-propylene, (Z)-1-chloro-2,3,3,3-tetrafluoropentene, and the step of forming the first mixture includes: mixing a part of the polyol, a part of the surfactant, the organic amine catalyst and the raw materials for preparing the first auxiliary foaming agent to form the first mixture; And / or, the raw materials for preparing the white material also include a second auxiliary foaming agent, and the second auxiliary foaming agent is selected from one or a combination of pentanes, 1,1-difluoroethane, 1,3,3,3-tetrafluoro-1-propylene, (Z)-1-chloro-2,3,3,3-tetrafluoropentene, and the step of forming the second mixture includes: mixing the raw materials for preparing the second mixture including the remaining part of the polyol, the remaining part of the surfactant, the LBA, the water and the second auxiliary foaming agent to form the second mixture.

6. The white material premixing process according to claim 5, characterized in that: The mass of the first auxiliary foaming agent is 0 to 15% of the mass of the polyol, and / or the mass of the second auxiliary foaming agent is 0 to 10% of the mass of the polyol.

7. The white material premixing process according to claim 1, characterized in that: The raw materials for preparing the white material also include a nucleating aid, and the white material premixing process also includes: Mixing the first mixture, the second mixture and the nucleating aid to obtain the white material; Alternatively, the step of forming the second mixture comprises: mixing the raw materials including the remaining part of the polyol, the remaining part of the surfactant, a part of the LBA, and the water to form a second mixture; the white material premixing process further comprises: mixing the raw materials including the nucleating aid and the remaining part of the LBA to form a third mixture; mixing the first mixture, the second mixture and the third mixture to obtain the white material; optionally, the mass ratio of the nucleating aid to the remaining part of the LBA is ≥1:10; Alternatively, the raw materials for preparing the white material further include at least one of a first auxiliary foaming agent and a second auxiliary foaming agent, wherein the first auxiliary foaming agent and the second auxiliary foaming agent are independently selected from one or a combination of pentane, 1,1-difluoroethane, 1,3,3,3-tetrafluoro-1-propylene, (Z)-1-chloro-2,3,3,3-tetrafluoropentene; the white material premixing process further includes: mixing the raw materials for preparing the nucleating aid including at least one of A to C to form a third mixture, and mixing the first mixture, the second mixture and the third mixture to obtain the white material: A: part or all of the first auxiliary blowing agent; B: part or all of the second auxiliary blowing agent; C: part of the LBA; Wherein, when there is a first auxiliary foaming agent that is not mixed with the nucleating aid, the first auxiliary foaming agent is used to mix with the raw materials for preparing the first mixture; when there is a second auxiliary foaming agent that is not mixed with the nucleating aid, the second auxiliary foaming agent is used to mix with the raw materials for preparing the second mixture; LBA that is not mixed with the nucleating aid is used to mix with the raw materials for preparing the second mixture.

8. The white material premixing process according to claim 7, characterized in that: The nucleating agent is selected from perfluoroolefin compounds; and / or the mass of the nucleating agent is 0-6% of the mass of the polyol.

9. The white material premixing process according to claim 1, characterized in that: The raw materials for preparing the white material also include an organic metal catalyst. The step of forming the first mixture includes: mixing the raw materials for preparing the white material including a portion of the polyol, a portion of the surfactant, the organic amine catalyst and the organic metal catalyst to form a first mixture.

10. The white material premixing process according to claim 9, characterized in that: The organic metal catalyst is selected from one or both of an organic tin catalyst and an organic bismuth catalyst; and / or the mass of the organic metal catalyst is 0 to 1% of the mass of the polyol.

11. The white material premixing process according to claim 1, characterized in that: The polyol is selected from one or both of polyether polyol and polyester polyol; and / or, the average hydroxyl value of the polyol is 350-450 mgKOH / g, and the average functionality is 4.5-6.5; and / or, in the process of forming the first mixture, a portion of the polyol accounts for 5% to 35% of the mass percentage of the polyol.

12. The white material premixing process according to claim 1, characterized in that: The surfactant is selected from silicone surfactants; and / or the mass of the surfactant is 2% to 6% of the mass of the polyol; and / or the mass ratio of a part of the surfactant to the remaining part thereof is 1-3:

1.

13. A white material premixing system, characterized in that: Used for premixing white materials including polyols, surfactants, organic amine catalysts, LBA and water, wherein the white material premixing system comprises: a first white material premixing device, a second white material premixing device and a third white material premixing device; The first white material premixing device is configured to transport the preparation raw materials including a part of the polyol, a part of the surfactant and the organic amine catalyst to the third white material premixing device; The second white material premixing device is configured to mix the preparation raw materials including the remaining part of the polyol, the remaining part of the surfactant, the LBA and the water, and transport them to the third white material mixing device; The third white material premixing device is connected to the first white material premixing device and the second white material premixing device at the same time.

14. The white material premixing system according to claim 13, characterized in that: The raw materials for preparing the white material further include a nucleating aid, and the white material premixing system further includes: a nucleating aid premixing device connected to the third white material premixing device, and the nucleating aid premixing device is configured to transport the raw materials including the nucleating aid to the third white material premixing device; Alternatively, the second white material premixing device is configured to mix the raw materials including the remaining part of the polyol, the remaining part of the surfactant, a part of the LBA and the water, and deliver them to the third white material mixing device; the nucleating agent premixing device is configured to mix the raw materials including the nucleating agent and the remaining part of the LBA, and deliver them to the third white material premixing device; Alternatively, the raw material for preparing the white material further includes at least one of a first auxiliary foaming agent and a second auxiliary foaming agent, wherein the first auxiliary foaming agent and the second auxiliary foaming agent are independently selected from one or a combination of pentane, 1,1-difluoroethane, 1,3,3,3-tetrafluoro-1-propylene, (Z)-1-chloro-2,3,3,3-tetrafluoropentene; the nucleating agent premixing device is further configured to mix the raw material for preparing the nucleating agent with at least one of A to C, and transport the mixture to the third white material premixing device: A: part or all of the first auxiliary blowing agent; B: part or all of the second auxiliary blowing agent; C: part of the LBA; Among them, when there is a first auxiliary foaming agent that is not mixed with the nucleating aid, the first auxiliary foaming agent is configured to be mixed with the prepared raw materials in the first white material premixing device; when there is a second auxiliary foaming agent that is not mixed with the nucleating aid, the second auxiliary foaming agent is configured to be mixed with the prepared raw materials in the second white material premixing device; the LBA that is not mixed with the nucleating aid is configured to be mixed with the prepared raw materials in the second white material premixing device.

15. A polyurethane foaming system, comprising the white material premixing system as claimed in claim 13 or 14, as well as a white material working tank, a black material working tank and a foaming machine; the third white material mixing device of the white material premixing system is connected to the white material working tank, and the foaming machine is simultaneously connected to the white material working tank and the black material working tank.

16. A polyurethane foaming method, characterized in that: The method comprises the steps of the white material premixing process as described in any one of claims 1 to 12, and further comprises: mixing the black material with the white material obtained by the white material premixing process, and foaming the mixture to obtain a polyurethane foam material.

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