Rigid polyurethane foam, method of manufacture and refrigeration appliance

Abstract

The application discloses rigid polyurethane foam, a preparation method and a refrigeration appliance, comprising: a combined polyether; isocyanate; foaming agent I, the foaming agent I is one of cyclopentane and isopentane or a mixture composed of cyclopentane and isopentane in any proportion; foaming agent II, the foaming agent II is one of pentafluoropropane and trifluoro-chloro-propylene or a mixture composed of pentafluoropropane and trifluoro-chloro-propylene in any proportion; and foaming agent III, the foaming agent III adopts perfluoromethyl vinyl ether. By adding perfluoromethyl vinyl ether as a foaming agent, the application overcomes the foam cavity problem of a low-boiling-point foaming system, reduces the foam molding density, improves the supporting capacity of low-density rigid polyurethane foam, and has low cost and high practicability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polyurethane, in particular to rigid polyurethane foam, preparation method and refrigeration appliance. BACKGROUND

[0002] Rigid polyurethane foam is widely used in refrigeration appliances due to its light weight and good thermal insulation performance. Rigid polyurethane foam mainly plays a role of heat insulation and support in refrigeration appliances, so the strength and thermal conductivity index are important indicators for evaluating the quality of the foam. The type of foaming agent is closely related to the indicators of polyurethane foam.

[0003] The foaming agents currently used in polyurethane foam mainly include three categories: alkane, hydrofluorocarbon and fluoroalkene. Alkanes mainly include cyclopentane and isopentane. This type of foaming system has high molding density during use, and the higher the density, the higher the cost. Moreover, the foaming time of the foam is long, and the production efficiency is low. Hydrofluorocarbons mainly include low-boiling tetrafluoroethane (HFC-134a), difluoroethane (152a) and conventional boiling pentafuoropropane (HFC-245fa). Low-boiling tetrafluoroethane and difluoroethane have poor compatibility in the combined polyether, which leads to many foam holes on the surface of the foam, and easily causes corrosion and pit problems to the inner liner of the refrigeration appliance. Although the conventional boiling pentafuoropropane has good compatibility, it has high GWP value and is not environmentally friendly, and has been banned in the European Union. Fluoroalkenes mainly include trifluoro-chloropropene (LBA). Although this type of foaming agent is environmentally friendly and has good thermal insulation performance, it has a high price and its use is limited. SUMMARY

[0004] In order to solve at least one defect existing in the current foaming system, the present application proposes a rigid polyurethane foam, a preparation method and a refrigeration appliance. By adding low-boiling perfluoromethyl vinyl ether as a foaming agent, the high compatibility of the substance with the combined polyether is utilized to overcome the air bubble problem of the low-boiling foaming system, reduce the molding density of the foam, and improve the support capacity of the low-density rigid polyurethane foam. It has low cost and high practicality.

[0005] The technical scheme adopted by the present application is to design a rigid polyurethane foam, which comprises:

[0006] a combined polyether;

[0007] isocyanate;

[0008] a foaming agent I, the foaming agent I being one of cyclopentane and isopentane or a mixture of cyclopentane and isopentane in any proportion;

[0009] a foaming agent II, the foaming agent II being one of pentafuoropropane and trifluoro-chloropropene or a mixture of pentafuoropropane and trifluoro-chloropropene in any proportion;

[0010] and a blowing agent III, the blowing agent III being perfluoromethyl vinyl ether.

[0011] Further, the combined polyether is 100 parts by mass, the isocyanate is 125-155 parts by mass, the blowing agent I is 7-15 parts by mass, the blowing agent II is 4-9 parts by mass, and the blowing agent III is 0-4 parts by mass.

[0012] Further, the combined polyether includes 40-70% polyether polyol, 5-15% polyester polyol, 2-4.5% amine catalyst, 1-4% water, and 2.5-7.5% silicone oil.

[0013] Further, the isocyanate has a viscosity of 150-300 mpa.s at 25℃, and the isocyanate has an isocyanate content of 30.5-35%.

[0014] The present application also proposes a preparation method of the hard polyurethane foam, including the following steps:

[0015] Step 1, the combined polyether, the blowing agent I and the blowing agent II are mixed uniformly according to the weight ratio to obtain mixed white material I;

[0016] Step 2, the mixed white material I and the blowing agent III are mixed uniformly according to the weight ratio to obtain mixed white material II;

[0017] Step 3, the mixed white material II and the isocyanate are respectively stored in the foaming machine;

[0018] Step 4, the mixed white material II and the isocyanate are mixed through the injection gun head of the foaming machine and then injected into the mold to be foamed, and the hard polyurethane foam is obtained after curing and demolding.

[0019] Further, the mixing condition of step 1 is temperature 20-25℃ and pressure 0.5-2 MPa.

[0020] Further, the mixing condition of step 2 is temperature 10-20℃ and pressure 0.7-2.5 MPa, and the mixed white material II of step 3 is conveyed to the foaming machine under the pressure of 0.7-2.5 MPa through the pipeline.

[0021] Further, the temperature of the mixed white material II in the foaming machine in step 3 is controlled at 15-19℃, and the temperature of the isocyanate in the foaming machine in step 3 is controlled at 17-26℃.

[0022] The present application also proposes a refrigeration appliance having the hard polyurethane foam.

[0023] In some embodiments, the thermal insulation layer of the refrigeration appliance uses the hard polyurethane foam.

[0024] Compared with the prior art, the present application introduces an environmentally friendly low-boiling full-fluoromethyl vinyl ether, on the one hand, by virtue of the low-boiling characteristics of the substance, the surface tension of the foaming agent system is low, and the gas nucleus is more easily vaporized to form uniform dispersion in the initial stage of raw material foaming, so that the cells are more delicate and uniform, and the foaming agent after vaporization exists in the form of gas in the cells due to the low boiling point, effectively avoiding the negative pressure contraction of the cells due to the liquefaction of the gas in the cells, thereby effectively reducing the foam density, so that the foam still has good anti-deformation support capacity at low density; on the other hand, the substance contains ether bonds, and the monomers in the combined polyether are mainly polyether polyols, by virtue of the similar compatibility principle, the low-boiling foaming agent has good compatibility in the foaming system, and is more uniformly dispersed in the entire foaming system, avoiding the rapid local aggregation of the low-boiling foaming agent in the foaming system during the foaming process to form large bubbles and burst, finally overcoming the surface void defect of the foam and improving the comprehensive performance of the low-density polyurethane foam. DETAILED DESCRIPTION

[0025] In order to make the technical problems, technical solutions and beneficial effects of the present application clearer, the present application will be further described in detail below in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application.

[0026] The present application proposes the specific formula composition of the rigid polyurethane foam as follows: combined polyether; isocyanate; foaming agent I; foaming agent II; foaming agent III. Among them, the foaming agent I is one of cyclopentane and isopentane or a mixture of cyclopentane and isopentane in any proportion. The foaming agent II is one of pentafluoropropane (245fa) and trifluoro-chloro-propylene (LBA) or a mixture of pentafluoropropane (245fa) and trifluoro-chloro-propylene (LBA) in any proportion, and the foaming agent III adopts perfluoromethyl vinyl ether. Generally, the weight fraction ratio of the rigid polyurethane foam formula is: 100 parts by mass of combined polyether, 125-155 parts by mass of isocyanate, 7-15 parts by mass of foaming agent I, 4-9 parts by mass of foaming agent II, and 0-4 parts by mass of foaming agent III.

[0027] In the foaming process of the rigid polyurethane foam, carbon dioxide is first generated by the reaction of isocyanate and water in the combined polyether or the physical foaming agent is vaporized by heat, so that the gas concentration increases rapidly to form bubbles, which are wrapped by the polyurethane resin to form image cells. The conventional pure pentane foaming system has high molding density in the use process due to the high boiling point of pentane, the higher the density, the higher the cost, and the longer the foaming time of the foam, the lower the production efficiency; the conventional low-boiling foaming system, such as tetrafluoroethane (HFC-134a) and difluoroethane (152a), has a high GWP value of HFC-134a, which has been banned in the European Union, and the compatibility of difluoroethane (152a) with the combined polyether is poor, resulting in many cells on the surface of the foam, which is easy to cause corrosion and suction pit problems to the inner liner of the refrigeration appliance.

[0028] The foaming agent III in the rigid polyurethane foam formula is an important component distinguishing from the existing foaming system, the boiling point of the foaming agent III is lower than that of the foaming agent I and the foaming agent II, the boiling point of the perfluoromethyl vinyl ether is -25.4℃, by adding the low-boiling perfluoromethyl vinyl ether as the foaming agent, on the one hand, the low-boiling characteristics of the substance are utilized, the surface tension of the foaming agent system is low, it is easier to gasify to form uniformly dispersed gas nuclei in the initial stage of raw material foaming, the cells are more delicate and uniform, and the foaming agent after gasification exists in the form of gas in the cell due to the low boiling point, effectively avoiding the negative pressure shrinkage of the cell due to the liquefaction of the gas in the cell, thereby effectively reducing the foam density, so that the foam still has good anti-deformation support capacity at low density; on the other hand, the substance contains ether bond, the monomer in the combined polyether is mainly polyether polyol, by using the similar compatibility principle, the low-boiling foaming agent has good compatibility in the foaming system, and is more uniformly dispersed in the entire foaming system, avoiding the local rapid aggregation of the low-boiling foaming agent in the foaming system to form large bubbles and break during the foaming process, finally overcoming the surface cavity defect of the foam and improving the comprehensive performance of the low-density polyurethane foam insulation layer.

[0029] In some embodiments of the present application, the combined polyether includes 40-70% polyether polyol, 5-15% polyester polyol, 2-4.5% amine catalyst, 1-4% water and 2.5-7.5% silicone oil, the viscosity of isocyanate at 25℃ is 150-300mpa.s, and the isocyanate content of isocyanate is 30.5-35%. It should be pointed out that the combined polyether and isocyanate are very mature in the application of preparing polyurethane foam, and the parameters and performance are known technology, and the specific components can be slightly adjusted according to the actual use requirements, and the present application does not make special limitation.

[0030] The present application also provides a preparation method of the rigid polyurethane foam, which comprises the following steps:

[0031] Step 1, the combined polyether, foaming agent I and foaming agent II are mixed uniformly according to the weight ratio to obtain mixed white material I, since the viscosity of the combined polyether is high, the viscosity at 20-25℃ is about 5500mpa.s, therefore, the foaming agent I and the foaming agent II with high boiling point (not easy to volatilize) are premixed in step 1, on the one hand, it is easier to mix, on the other hand, it can effectively reduce the system viscosity, which is beneficial to the mixing of the low-boiling foaming agent III in the subsequent step, so that the components are mixed more uniformly, avoiding the influence of uneven foaming agent mixing on the foaming quality;

[0032] Step 2, the mixed white material I and the foaming agent III are mixed uniformly according to the weight ratio to obtain mixed white material II, since the foaming agent III itself has low boiling point and is easy to volatilize, therefore, the foaming agent III needs to be mixed with the mixed white material I at a lower temperature to improve the overall mixing effect;

[0033] Step 3, the mixed white material II and isocyanate are respectively stored in the black and white material tanks of the foaming machine, since the mixed white material II will immediately react with isocyanate to foam once contacted, so the two materials must be stored separately;

[0034] Step 4, the mixed white material II and isocyanate are respectively introduced into the injection gun head of the foaming machine through different pipes, mixed and immediately injected into the cavity of the mold to be foamed, and the rigid polyurethane foam is obtained after curing and demolding.

[0035] The following part of the examples will be described in detail.

[0036] Example 1

[0037] The preparation formula is as follows:

[0038] The combined polyether is 100 parts by mass, the isocyanate is 144 parts by mass, the foaming agent I is 12 parts by mass, the foaming agent II is 7 parts by mass, and the foaming agent III is 1 part by mass, the foaming agent I is cyclopentane, the foaming agent II is pentafluoropropane (245fa), and the foaming agent III is perfluoromethyl vinyl ether.

[0039] The preparation process is as follows:

[0040] Under the environmental conditions of temperature 20-25℃ and pressure 0.5-2Mpa, the combined polyether, foaming agent I and foaming agent II are mixed uniformly according to the weight ratio to obtain the mixed white material I;

[0041] Under the environmental conditions of temperature 10-20℃ and pressure 0.7-2.5Mpa, the mixed white material I and foaming agent III are mixed uniformly according to the weight ratio to obtain the mixed white material II;

[0042] The mixed white material II is transported to the white material tank of the foaming machine through the pipeline under the pressure of 0.7-2.5MPa, and the temperature of the mixed white material II is controlled at 15-19℃;

[0043] The isocyanate is stored in the black material tank of the foaming machine, and the temperature of the isocyanate is controlled at 17-26℃;

[0044] The mixed white material II and isocyanate are introduced into the injection gun head, mixed and injected into the mold to be foamed through the nozzle of the gun head, and the rigid polyurethane foam is obtained after curing and demolding.

[0045] The overfilling rate of the rigid polyurethane foam prepared in Example 1 is 15%, the compressive strength is 173kpa, the thermal conductivity is 18.90mw / m.k, and the low temperature dimensional change rate is 0.33%.

[0046] Example 2

[0047] The preparation formula is as follows:

[0048] The combined polyether is 100 parts by mass, the isocyanate is 142.2 parts by mass, the foaming agent I is 12.2 parts by mass, the foaming agent II is 5.5 parts by mass, and the foaming agent III is 2 parts by mass. The foaming agent I is cyclopentane, the foaming agent II is pentafluoropropane (245fa), and the foaming agent III is perfluoromethyl vinyl ether.

[0049] The preparation process is as follows:

[0050] Under the environmental conditions of temperature 20-25℃ and pressure 0.5-2Mpa, the combined polyether, the foaming agent I and the foaming agent II are mixed uniformly according to the weight ratio to obtain mixed white material I;

[0051] Under the environmental conditions of temperature 10-20℃ and pressure 0.7-2.5Mpa, the mixed white material I and the foaming agent III are mixed uniformly according to the weight ratio to obtain mixed white material II;

[0052] The mixed white material II is conveyed to the white material tank of the foaming machine through the pipeline under the pressure of 0.7-2.5MPa, and the temperature of the mixed white material II is controlled at 15-19℃;

[0053] The isocyanate is stored in the black material tank of the foaming machine, and the temperature of the isocyanate is controlled at 17-26℃;

[0054] The mixed white material II and the isocyanate are fed into the injection gun head, and then injected into the mold to be foamed through the nozzle of the gun head after mixing, and the rigid polyurethane foam is obtained after curing and demolding.

[0055] The overfilling rate of the rigid polyurethane foam prepared in Example 2 is 15%, the compressive strength is 198kpa, the thermal conductivity is 18.78mw / m.k, and the low-temperature dimensional change rate is 0.21%.

[0056] Example 3

[0057] The preparation formula is as follows:

[0058] The combined polyether is 100 parts by mass, the isocyanate is 144 parts by mass, the foaming agent I is 12.7 parts by mass, the foaming agent II is 4 parts by mass, and the foaming agent III is 3 parts by mass. The foaming agent I is cyclopentane, the foaming agent II is pentafluoropropane (245fa), and the foaming agent III is perfluoromethyl vinyl ether.

[0059] The preparation process is as follows:

[0060] Under the environmental conditions of temperature 20-25℃ and pressure 0.5-2Mpa, the combined polyether, the foaming agent I and the foaming agent II are mixed uniformly according to the weight ratio to obtain mixed white material I;

[0061] The mixed white material I and the foaming agent III are mixed uniformly under the environmental conditions of temperature 10-20℃ and pressure 0.7-2.5Mpa to obtain the mixed white material II;

[0062] The mixed white material II is transported to the white material tank of the foaming machine under the pressure of 0.7-2.5Mpa through the pipeline, and the temperature of the mixed white material II is controlled at 15-19℃;

[0063] The isocyanate is stored in the black material tank of the foaming machine, and the temperature of the isocyanate is controlled at 17-26℃;

[0064] The mixed white material II and the isocyanate are introduced into the injection gun head, and then injected into the mold to be foamed through the nozzle of the gun head after mixing, and the rigid polyurethane foam is obtained after curing and demolding.

[0065] The overfilling rate of the rigid polyurethane foam prepared in Example 3 is 15%, the compressive strength is 206kpa, the thermal conductivity is 18.73mw / m.k, and the low-temperature dimensional change rate is 0.19%.

[0066] Comparative Example 4

[0067] The preparation formula is as follows:

[0068] The combined polyether is 100 parts by mass, the isocyanate is 141.6 parts by mass, the foaming agent I is 12 parts by mass, and the foaming agent II is 7 parts by mass, the foaming agent I is cyclopentane, the foaming agent II is pentafluoropropane (245fa), and no foaming agent III is added in Comparative Example 4.

[0069] The preparation process is as follows:

[0070] The combined polyether, the foaming agent I and the foaming agent II are mixed uniformly under the environmental conditions of temperature 20-25℃ and pressure 0.5-2Mpa to obtain the mixed white material I;

[0071] The mixed white material I is transported to the white material tank of the foaming machine under the pressure of 0.5-2Mpa through the pipeline, and the temperature of the mixed white material I is controlled at 20-25℃;

[0072] The isocyanate is stored in the black material tank of the foaming machine, and the temperature of the isocyanate is controlled at 17-26℃;

[0073] The mixed white material I and the isocyanate are introduced into the injection gun head, and then injected into the mold to be foamed through the nozzle of the gun head after mixing, and the rigid polyurethane foam is obtained after curing and demolding.

[0074] The overfilling rate of the rigid polyurethane foam prepared in Comparative Example 4 is 15%, the compressive strength is 147kpa, the thermal conductivity is 19.12mw / m.k, and the low-temperature dimensional change rate is 0.46%.

[0075] Table 1 below is a table of formulation compositions and foam performance comparison data for Examples 1-4 and Comparative Example 5

[0076] Material and trial production unit Example 1 Example 2 Example 3 Comparative Example 4 combined polyether parts by weight 100 100 100 100 isocyanate parts by weight 144 142.2 144 141.6 cyclopentane parts by weight 12 12.3 12.7 12 LBA parts by weight / / / / 245fa parts by weight 7 5.5 4 7 perfluoromethyl vinyl ether parts by weight 1 2 3 / overfill rate ％ 15 15 15 15 compression strength kpa 173 198 206 147 coefficient of thermal conductivity mw / m.k 18.90 18.78 18.73 19.12 low temperature dimensional change rate ％ 0.33 0.21 0.19 0.46

[0077] Example 5

[0078] The formulation was prepared as follows:

[0079] The combined polyether was 100 parts by mass, the isocyanate was 144 parts by mass, the blowing agent I was 12 parts by mass, the blowing agent II was 7 parts by mass, and the blowing agent III was 1 part by mass. The blowing agent I was cyclopentane, the blowing agent II was trifluorochloropropene (LBA), and the blowing agent III was perfluoromethyl vinyl ether.

[0080] The preparation process was as follows:

[0081] Under the environmental conditions of a temperature of 20-25°C and a pressure of 0.5-2 MPa, the combined polyether, the blowing agent I, and the blowing agent II were mixed uniformly according to the weight proportions to obtain mixed white material I;

[0082] Under the environmental conditions of a temperature of 10-20°C and a pressure of 0.7-2.5 MPa, the mixed white material I and the blowing agent III were mixed uniformly according to the weight proportions to obtain mixed white material II;

[0083] The mixed white material II was transported to the white material tank of the foaming machine through a pipeline under a pressure of 0.7-2.5 MPa, and the temperature of the mixed white material II was controlled at 15-19°C;

[0084] The isocyanate was stored in the black material tank of the foaming machine, and the temperature of the isocyanate was controlled at 17-26°C;

[0085] The mixed white material II and the isocyanate were introduced into the injection gun head, mixed, and then injected into the mold to be foamed through the nozzle of the gun head, and the rigid polyurethane foam was obtained after curing and demolding.

[0086] The rigid polyurethane foam prepared in Example 5 had an overfilling rate of 15%, a compressive strength of 165 kPa, a thermal conductivity of 18.85 mw / m.k, and a low-temperature dimensional change rate of 0.32%.

[0087] Example 6

[0088] The formulation was prepared as follows:

[0089] The combined polyether was 100 parts by mass, the isocyanate was 142.2 parts by mass, the blowing agent I was 12.2 parts by mass, the blowing agent II was 5.5 parts by mass, and the blowing agent III was 2 parts by mass. The blowing agent I was cyclopentane, the blowing agent II was trifluorochloropropene (LBA), and the blowing agent III was perfluoromethyl vinyl ether.

[0090] The preparation process is as follows:

[0091] Under the environmental conditions of temperature 20-25°C and pressure 0.5-2 Mpa, the combined polyether, foaming agent I and foaming agent II are mixed uniformly according to the weight ratio to obtain mixed white material I;

[0092] Under the environmental conditions of temperature 10-20°C and pressure 0.7-2.5 Mpa, the mixed white material I and foaming agent III are mixed uniformly according to the weight ratio to obtain mixed white material II;

[0093] The mixed white material II is transported to the white material tank of the foaming machine through a pipeline under the pressure of 0.7-2.5 MPa, and the temperature of the mixed white material II is controlled at 15-19°C;

[0094] The isocyanate is stored in the black material tank of the foaming machine, and the temperature of the isocyanate is controlled at 17-26°C;

[0095] The mixed white material II and the isocyanate are introduced into the injection gun head, mixed and then injected into the mold to be foamed through the nozzle of the gun head, and the rigid polyurethane foam is obtained after curing and demolding.

[0096] The overfilling rate of the rigid polyurethane foam prepared in Example 6 is 15%, the compressive strength is 203 kPa, the thermal conductivity is 18.70 mw / m.k, and the low-temperature dimensional change rate is 0.23%.

[0097] Example 7

[0098] The preparation formula is as follows:

[0099] The combined polyether is 100 parts by mass, the isocyanate is 144 parts by mass, the foaming agent I is 12.7 parts by mass, the foaming agent II is 4 parts by mass, and the foaming agent III is 3 parts by mass. The foaming agent I is cyclopentane, the foaming agent II is trifluoro-chloro-propylene (LBA), and the foaming agent III is perfluoromethyl vinyl ether.

[0100] The preparation process is as follows:

[0101] Under the environmental conditions of temperature 20-25°C and pressure 0.5-2 Mpa, the combined polyether, foaming agent I and foaming agent II are mixed uniformly according to the weight ratio to obtain mixed white material I;

[0102] Under the environmental conditions of temperature 10-20°C and pressure 0.7-2.5 Mpa, the mixed white material I and foaming agent III are mixed uniformly according to the weight ratio to obtain mixed white material II;

[0103] The mixed white material II is transported to the white material tank of the foaming machine through a pipeline under the pressure of 0.7-2.5 MPa, and the temperature of the mixed white material II is controlled at 15-19°C;

[0104] The isocyanate is stored in the black material tank of the foaming machine, and the temperature of the isocyanate is controlled at 17-26°C;

[0105] The mixed white material II and the isocyanate are introduced into the injection material gun head, and after mixing, they are injected into the mold to be foamed through the nozzle of the gun head, and after curing and demolding, the rigid polyurethane foam is obtained.

[0106] The overfilling rate of the rigid polyurethane foam prepared in Example 7 is 15%, the compressive strength is 211 kpa, the thermal conductivity is 18.67 mw / m.k, and the low-temperature dimensional change rate is 0.21%.

[0107] Comparative Example 8

[0108] The preparation formula is as follows:

[0109] The combined polyether is 100 parts by mass, the isocyanate is 141.6 parts by mass, the foaming agent I is 12 parts by mass, and the foaming agent II is 7 parts by mass. The foaming agent I is cyclopentane, the foaming agent II is trifluoro-chloro-propylene (LBA), and no foaming agent III is added in Comparative Example 4.

[0110] The preparation process is as follows:

[0111] Under the environmental conditions of temperature 20-25°C and pressure 0.5-2 Mpa, the combined polyether, the foaming agent I and the foaming agent II are mixed uniformly according to the weight ratio to obtain the mixed white material I;

[0112] The mixed white material I is transported to the white material tank of the foaming machine through the pipeline under the pressure of 0.5-2 Mpa, and the temperature of the mixed white material I is controlled at 20-25°C;

[0113] The isocyanate is stored in the black material tank of the foaming machine, and the temperature of the isocyanate is controlled at 17-26°C;

[0114] The mixed white material I and the isocyanate are introduced into the injection material gun head, and after mixing, they are injected into the mold to be foamed through the nozzle of the gun head, and after curing and demolding, the rigid polyurethane foam is obtained.

[0115] The overfilling rate of the rigid polyurethane foam prepared in Comparative Example 8 is 15%, the compressive strength is 146 kpa, the thermal conductivity is 18.90 mw / m.k, and the low-temperature dimensional change rate is 0.42%.

[0116] Table 2 below is a comparison table of the formula composition and foam performance data of Example 5 to Comparative Example 8

[0117] Material and trial production unit Example 5 Example 6 Example 7 Comparative Example 8 combined polyether parts by weight 100 100 100 100 isocyanate parts by weight 144 142.2 144 141.6 cyclopentane parts by weight 12 12.3 12.7 12 LBA parts by weight 7 5.5 4 6.8 245fa parts by weight / / / / perfluoromethyl vinyl ether parts by weight 1 2 3 / overfill rate ％ 15 15 15 15 compression strength kpa 165 203 211 146 coefficient of thermal conductivity mw / m.k 18.85 18.70 18.67 18.90 low temperature dimensional change rate ％ 0.32 0.23 0.21 0.42

[0118] According to the data shown in Table 1 and Table 2, it can be found that the polyurethane foam prepared by adding low-boiling full-fluoromethyl vinyl ether as a foaming agent in the foaming system has low density, good heat preservation performance, high strength, good low-temperature deformation resistance, and good comprehensive performance of the foam.

[0119] It should be noted that the above embodiments are only part of the embodiments of the present application, not all. The environmental conditions during specific preparation can be slightly adjusted according to different actual use requirements, and the present application does not specially limit this.

[0120] The present application also provides a refrigeration appliance having the rigid polyurethane foam described above, which includes but is not limited to a refrigerator and the like. In some embodiments, the rigid polyurethane foam is used in the heat preservation layer of the refrigeration appliance, so as to effectively reduce the production cost of the refrigeration appliance, and due to the good heat preservation performance of the rigid polyurethane foam, the energy consumption of the refrigeration appliance can be effectively reduced, and energy saving and environmental protection are achieved.

[0121] It should be noted that the terms used above are only for the purpose of describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. When the terms "comprise" and / or "include" are used in the specification, they indicate the presence of the features, steps, operations, devices, components and / or their combinations. The order of the actions, steps, etc. in the devices and methods shown in the specification can be implemented in any order as long as the output of the previous process is not used in the subsequent process, unless the order is specifically limited. The use of similar ordinal terms does not mean that the implementation must be in accordance with such an order.

[0122] Techniques, methods, and devices known to those of ordinary skill in the relevant art can not be discussed in detail herein, but should be considered as part of the description of the application. In all examples shown and discussed herein, any specific value should be interpreted as merely exemplary, and not as a limitation. Therefore, other examples of the exemplary embodiments can have different values.

[0123] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. Rigid polyurethane foam characterized in that, comprising: a combination polyether; an isocyanate; a blowing agent I, which is one of cyclopentane and isopentane or a mixture of cyclopentane and isopentane in any proportion; a blowing agent II, which is one of pentafluoropropane and trifluorochloropropene or a mixture of pentafluoropropane and trifluorochloropropene in any proportion; and a blowing agent III, which is perfluoromethyl vinyl ether; the combination polyether is 100 parts by mass, the isocyanate is 125-155 parts by mass, the blowing agent I is 7-15 parts by mass, the blowing agent II is 4-9 parts by mass, and the blowing agent III is 1-3 parts by mass; the combination polyether comprises 40-70% polyether polyol, 5-15% polyester polyol, 2-4.5% amine catalyst, 1-4% water, and 2.5-7.5% silicone oil; the isocyanate has a viscosity of 150-300 mpa.s at 25°C, and the isocyanate has an isocyanate content of 30.5-35%.

2. A process for the preparation of rigid polyurethane foam, said process being used for the preparation of the rigid polyurethane foam according to claim 1, characterized in that, comprising the following steps: Step 1, uniformly mixing the combination polyether, the blowing agent I, and the blowing agent II according to the weight ratio to obtain mixed white material I; Step 2, uniformly mixing the mixed white material I and the blowing agent III according to the weight ratio to obtain mixed white material II; Step 3, storing the mixed white material II and the isocyanate in a foaming machine respectively; Step 4, mixing the mixed white material II and the isocyanate through the injection gun head of the foaming machine and injecting into a mold to be foamed, and obtaining rigid polyurethane foam after curing and demolding; wherein the mixing condition of Step 1 is temperature 20-25°C and pressure 0.5-2 MPa; the mixing condition of Step 2 is temperature 10-20°C and pressure 0.7-2.5 MPa, and the mixed white material II of Step 3 is conveyed to the foaming machine through a pipeline under a pressure of 0.7-2.5 MPa; the temperature of the mixed white material II in the foaming machine of Step 3 is controlled at 15-19°C, and the temperature of the isocyanate in the foaming machine of Step 3 is controlled at 17-26°C.

3. A refrigeration appliance characterised in that, The refrigeration appliance has the rigid polyurethane foam of claim 1.

4. The refrigeration appliance of claim 3, wherein, The rigid polyurethane foam is used in the insulation layer of the refrigeration appliance.