Environment-friendly rigid polyurethane foam as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of thermosetting rigid polyurethane foam, and discloses environment-friendly rigid polyurethane foam as well as a preparation method and application thereof. The environment-friendly rigid polyurethane foam disclosed by the invention is prepared from the following components in parts by weight: 95 to 100 parts of polyol, 1.8 to 2.5 parts of foam stabilizer, 1.5 to 2.3 parts of catalyst, 15 to 30 parts of foaming agent, 130 to 150 parts of organic isocyanate and 1.5 to 2.3 parts of water, the foam stabilizer is a silicon foam stabilizer containing a Si-C structure; the catalyst comprises a foaming catalyst, a gel catalyst and a trimerization catalyst; the foaming agent is 2-chloro-3, 3, 3-trifluoropropene, and the foaming agent is 2-chloro-3, 3, 3-trifluoropropene. The environment-friendly rigid polyurethane foam disclosed by the invention is fine and uniform in foam holes and excellent in heat conductivity coefficient, so that the product is more energy-saving. The production process is simple and suitable for large-scale production. The device can be widely applied to the field of household appliances such as refrigerators, freezers and water heaters.

Description

Technical Field

[0001] The invention relates to the technical field of thermosetting rigid polyurethane foam, and in particular to an environmentally friendly rigid polyurethane foam and a preparation method and application thereof. Background Art

[0002] Rigid polyurethane foam has excellent thermal insulation properties and can be widely used in home appliances such as refrigerators, freezers, and water heaters. According to the requirements of the Montreal Protocol, the impact of the blowing agent used to prepare rigid polyurethane foam on the environment has received increasing attention.

[0003] At present, the polyurethane foaming agent systems in the home appliance field mainly include cyclopentane (including cyclo / isopentane), cyclopentane / HFC-245fa, cyclopentane / HFO-1233zd, and a small amount of HFC-134a, HFC-365mfc and pentane blending systems. These foaming agents each have their own advantages and disadvantages. Pentane foaming agents are environmentally friendly and low in cost, but they are flammable and explosive, and their production and operation are highly dangerous. They also have a high boiling point and a high thermal conductivity of the foam, which cannot meet the company's cost control and increasingly stringent product energy consumption requirements; HFC-245fa foaming agent is not flammable or explosive, and has a low foam thermal conductivity. Due to its relatively low boiling point, the foam density is low, which is conducive to cost control, but its GWP value (greenhouse potential) is high and no longer meets the environmental protection regulations of the European Union, the United States, Japan and other regions, and will eventually be replaced; HFO-1233zd (1-chloro-3,3,3-trifluoropropene) foaming agent has an ODP of 0, a GWP of less than 10, is not flammable or explosive, and has a low gas phase thermal conductivity, but when it is used as a foaming agent, there are problems with the long-term stability of the foaming system mixed with this foaming agent. Specifically, on the one hand, when the system contains a specific catalyst, especially an amine catalyst, a reaction may occur; on the other hand, excessive water content in the foaming system may accelerate the reaction of HFO-1233zd and the amine catalyst. The polyurethane composite material produced by the system has poor storage stability. The prior art uses the system immediately after mixing, and the composite material in the pipeline and storage tank cannot be stored for a long time, which brings inconvenience to practical applications. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide an environmentally friendly rigid polyurethane foam and its preparation method and application. The environmentally friendly rigid polyurethane foam is a thermosetting rigid polyurethane foam, which is environmentally friendly, low in density, low in thermal conductivity, and can be stored for a long time.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] In a first aspect, the present invention provides an environmentally friendly rigid polyurethane foam, comprising the following components by weight: 95 to 100 parts of polyol, 1.8 to 2.5 parts of foam stabilizer (preferably, 2 to 2.3 parts), 1.5 to 2.3 parts of catalyst (preferably, 2 to 2.2 parts), 15 to 30 parts of foaming agent, 130 to 150 parts of organic isocyanate and 1.5 to 2.3 parts of water;

[0007] The foam stabilizer is a silicon foam stabilizer containing a Si-C structure;

[0008] The catalyst includes a foaming catalyst, a gel catalyst and a trimerization catalyst;

[0009] The foaming agent is 2-chloro-3,3,3-trifluoropropene.

[0010] The environmentally friendly rigid polyurethane foam of the present invention has fine and uniform pores and excellent thermal conductivity, which can make the product more energy-efficient; it has good aging performance, can accelerate the demoulding speed of polyurethane foam, and improve the efficiency of product foaming production. The present invention adopts a foaming agent 2-chloro-3,3,3-trifluoropropene (HFO-1233xf), which has an ODP of 0, a low GWP value, is non-flammable, environmentally friendly, and has good environmental protection; in the system of the present invention, 2-chloro-3,3,3-trifluoropropene has a steric effect, contains double bonds and halogen atoms, is easy to react with nucleophilic reagents, is matched with a specific catalyst and a foam stabilizer for synergistic effect, has better foam storage stability, better low-temperature dimensional stability, and has better environmental protection and safety than the cyclopentane system.

[0011] In the environmentally friendly rigid polyurethane foam system of the present invention, the weight portion of water is 1.5 to 2.3 parts. Exceeding this range may cause changes in foam properties. If the water content is too low, the fluidity of the system will deteriorate and the foaming rate will decrease; if the water content is too high, the molecular bonds of the foam stabilizer will break, thereby increasing the thermal conductivity. In addition, too much water will also reduce the adhesion between the foam and the product surface, causing a "delamination" phenomenon.

[0012] As a preferred embodiment of the environmentally friendly rigid polyurethane foam described in the present invention, the polyol includes polyether polyol A, polyether polyol B, polyether polyol C and polyester polyol; the mass ratio of polyether polyol A, polyether polyol B, polyether polyol C and polyester polyol is (25-35):(25-35):(15-25):(10-20);

[0013] The polyether polyol A has an average functionality of 6.0 and a hydroxyl value of 400 to 480 mgKOH / g;

[0014] The polyether polyol B has an average functionality of 3.7 and a hydroxyl value of 330 to 420 mgKOH / g;

[0015] The polyether polyol C has an average functionality of 4.9 and a hydroxyl value of 400 to 450 mgKOH / g;

[0016] The polyester polyol has an average functionality of 2.8 and a hydroxyl value of 250 to 350 mgKOH / g.

[0017] As a preferred embodiment of the environmentally friendly rigid polyurethane foam of the present invention, the polyester polyol is an aromatic polyester polyol. In the system of the present invention, the aromatic polyester polyol contains a benzene ring structure, which can further increase the strength and dimensional stability of the foam and reduce the thermal conductivity of the foam.

[0018] As a preferred embodiment of the environmentally friendly rigid polyurethane foam described in the present invention, the foam stabilizer is an organic siloxane polyoxyolefin graft copolymer. Further, the foam stabilizer is preferably a DS2100 silicone oil produced by Zhongshan Dongjun Chemical Co., Ltd., which is not easy to hydrolyze and can further improve the storage stability of the foaming system; it has a good nucleation effect, can reduce the thermal conductivity of the foam, and can promote the compatibility between the foaming systems, improve the bubbles and fluidity of the foam surface.

[0019] As a preferred embodiment of the environmentally friendly rigid polyurethane foam described in the present invention, the foaming catalyst is N-methylcyclohexylamine; the gelling catalyst is dimethylcyclohexylamine; and the trimerization catalyst is (2-hydroxypropyl)trimethylammonium formate. The use of the catalyst system can not only make the foaming white material system have long-term storage stability, but the preferred catalyst combination also makes the entire reaction process more balanced, provides excellent flow dispersion performance for the polyurethane foam system, and also makes the prepared foam more dense and uniform, which is conducive to reducing the thermal conductivity, so that the product has a better energy-saving effect.

[0020] As a preferred embodiment of the environmentally friendly rigid polyurethane foam described in the present invention, the mass ratio of the foaming catalyst, the gel catalyst and the trimerization catalyst is (0.4-0.8):(0.3-1.2):(0.2-0.8).

[0021] As a preferred embodiment of the environmentally friendly rigid polyurethane foam of the present invention, the organic isocyanate is polymethylene polyphenyl polyisocyanate, with a viscosity of 350-500 mPa.s and an isocyanate content of 30.5% to 32%, such as PAPI27 of DOW, 44V-20L of Bayer, M20S of BASF, Suprasec-5005 of Huntsman, PM2010 and PM200 of Yantai Wanhua, etc.

[0022] In a second aspect, the present invention provides a method for preparing an environmentally friendly rigid polyurethane foam, comprising the following steps:

[0023] S1: uniformly mixing the polyol, foam stabilizer, catalyst and water according to the weight proportions to obtain a first mixture;

[0024] S2: uniformly mixing the first mixture with the foaming agent to obtain a second mixture;

[0025] S3: The second mixture and the organic polyisocyanate are mixed under high pressure through a foaming gun head and injected into the foaming cavity for mixing and foaming.

[0026] As a preferred embodiment of the preparation method described in the present invention, steps S1 to S2 are carried out at a material temperature of 15°C to 25°C; step S3 is carried out at a material temperature of 15°C to 20°C; the foaming cavity is preheated at 35°C to 45°C, and the gun tip pressure of the foaming gun is 110 bar to 160 bar.

[0027] In a third aspect, the present invention applies the environmentally friendly rigid polyurethane foam in the field of household appliances, preferably in refrigerators, freezers, and water heaters.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1) The present invention adopts HFO-1233xf foaming agent, which has an ODP of 0, a low GWP value, is non-flammable, environmentally friendly, and has good environmental protection properties, and meets the requirements of domestic and foreign environmental protection laws and regulations and the needs of future development;

[0030] 2) The HFO-1233xf blowing agent used in the present invention in conjunction with a specific catalyst and a foam stabilizer can make the combined polyether containing the blowing agent have good storage stability and can be stored for a long time to ensure production stability;

[0031] 3) The system of the present invention adopts the blowing agent HFO-1233xf, which has a low gas phase thermal conductivity, a suitable boiling point and a high vapor pressure, so that the entire polyurethane foaming system has good fluidity and good process operability, and the prepared rigid polyurethane foam has good performance, relatively low density, high compression strength, fine and uniform pores, and low thermal conductivity, which can produce obvious energy-saving and consumption-reducing effects, making the product more energy-efficient; in particular, since the polyurethane foam of the present invention has excellent thermal insulation performance, the thermal conductivity can be as low as 16.5mW / mK, therefore, it can replace part of the vacuum insulation board and has obvious cost advantages when used in energy-saving refrigerators;

[0032] 4) The rigid polyurethane foam prepared in the present invention has good dimensional stability when the density is low;

[0033] 5) The rigid polyurethane foam produced by the present invention has good aging performance, can accelerate the demoulding speed of the polyurethane foam, and improve the efficiency of product foaming production.

[0034] 6) The production process of the present invention is simple, no technical modification of existing equipment is required, and it is suitable for large-scale production. DETAILED DESCRIPTION

[0035] To better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments. It should be understood by those skilled in the art that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0036] Unless otherwise specified, the experimental methods used in the examples are all conventional methods; the materials, reagents, etc. used, unless otherwise specified, can be obtained from commercial channels.

[0037] In the following examples, the performance test standards are measured according to the following national standards:

[0038] (1) Free cell density, molded core density: GB / T 6343-95 Density test of polyurethane foam plastics;

[0039] (2) Compression strength: GB / T 8813-2008 Determination of compression properties of rigid foam plastics;

[0040] (3) Thermal conductivity: GB / T 10295-2008 Determination of steady-state thermal resistance and related properties of insulation materials - Heat flow meter method;

[0041] (4) Dimensional stability: GB / T 8811-2008 Determination of linear dimensions of foam plastics and rubber;

[0042] (5) GWP value of blowing agent: The GWP value of carbon dioxide is 1, and the ratio of other gases to carbon dioxide is the GWP value of the gas (data are all from the IPCC assessment report);

[0043] (6) Gel time: the time from when the polyurethane foam stock solution is mixed to when the rod placed in the foam is pulled out of the foam in a fibrous shape;

[0044] (7) Demolding time: the time from the injection of polyurethane foaming solution into the mold cavity to the curing and complete molding;

[0045] (8) Pore diameter range: measured by electron microscope SEM;

[0046] The raw materials used in the following examples and comparative examples are described as follows, but are not limited to these materials:

[0047] Polyol A, polyether polyol, average functionality 6.0, hydroxyl value 400-480 mgKOH / g, purchased from Hongbaoli Co., Ltd.;

[0048] Polyol B, polyether polyol, average functionality of 3.7, hydroxyl value of 330-420 mgKOH / g, purchased from Hongbaoli Co., Ltd.;

[0049] Polyol C, polyether polyol, average functionality of 4.9, hydroxyl value of 400-450 mgKOH / g, purchased from Hongbaoli Co., Ltd.;

[0050] Polyol D, polyester polyol, has an average functionality of 2.8, a hydroxyl value of 250-350 mgKOH / g, a brand number of 3152, and was purchased from Nanjing Sitaipan Company.

[0051] Foam stabilizer 1, brand B8492, purchased from Evonik;

[0052] Foam stabilizer 2, brand SD2100, was purchased from Zhongshan Dongjun Chemical Co., Ltd.

[0053] Catalyst 1, pentamethyldiethylenetriamine (PC-5), purchased from Air Products and Chemicals;

[0054] Catalyst 2, tris(dimethylaminopropyl)hexahydrotriazine (PC-41), purchased from Air Products and Chemicals;

[0055] Catalyst 3, N-methylcyclohexylamine (PC-21), purchased from Air Products and Chemicals;

[0056] Catalyst 4, dimethylcyclohexylamine (PC-8), purchased from Air Products and Chemicals;

[0057] Catalyst 5, (2-hydroxypropyl)trimethylammonium formate (TMR-2), was purchased from Air Products and Chemicals.

[0058] Blowing agent 1, cyclopentane, purchased from Meilong Chemical;

[0059] Blowing agent 2, HFO-1233zd (1-chloro-3,3,3-trifluoropropene), purchased from Honeywell;

[0060] Blowing agent 3, HFO-1233xf (2-chloro-3,3,3-trifluoropropene), purchased from Huanxin Fluoro Materials Co., Ltd.;

[0061] Organic polyisocyanate, commercially available.

[0062] The components of the rigid polyurethane foams of Examples 1 to 4 and Comparative Examples 1 to 9 are shown in Tables 1 and 2.

[0063] The preparation methods of the rigid polyurethane foams of Examples 1 to 4 and Comparative Examples 1 to 9 are as follows:

[0064] S1: at a material temperature of 15° C. to 25° C., uniformly mixing polyol, foam stabilizer, catalyst and water in parts by weight to obtain a first mixture;

[0065] S2: uniformly mixing the first mixture with a foaming agent through a static mixing device at a material temperature of 15° C. to 25° C. to obtain a second mixture;

[0066] S3: Under the condition of material temperature of 15℃~20℃, the above second mixture and corresponding weight parts of organic polyisocyanate are mixed by high pressure through a foaming gun tip and injected into the foaming cavity preheated to 35℃~45℃ for mixing and foaming. The gun tip pressure is 110bar~160bar to prepare polyurethane foam.

[0067] Among them, the overfilling coefficient of the foaming material in the foaming cavity is 15% to 30%. Within the specified time, the product is demoulded from the mold and then subjected to relevant tests, as shown in Tables 1 and 2.

[0068] Table 1 Components (parts by weight) and performance test results of rigid polyurethane foam samples in Example

[0069] Components Example 1 Example 2 Example 3 Example 4 Polyol A 25 35 30 35 Polyol B 35 25 30 30 Polyol C 15 20 20 15 Polyol D 20 15 15 15 water 1.8 1.8 1.7 1.7 Foam stabilizer 2 2.2 2.2 2.3 2.3 Catalyst 3 0.5 0.45 0.5 0.6 Catalyst 4 0.9 0.95 1.0 0.8 Catalyst 5 0.7 0.8 0.6 0.6 Foaming agent 3 16 22 28 32 Organic polyisocyanate 130 135 143 146 GWP value of foaming agent 1 1 1 1 Gel time (s) 40 40 41 41 <![CDATA[Free bubble density (kg / m 3 )]]> 22.88 22.42 22.02 21.53 <![CDATA[Average molded core density (kg / m 3 )]]> 29.99 29.56 29.48 29.25 Demolding time(s) 120 120 120 100 Pore ​​diameter range (μm) 150-180 150-180 130-180 130-180 Average thermal conductivity (10℃)(mW / mK) 17.33 17.02 16.58 16.32 Minimum compressive strength (vertical) (KPa) 131 135 137 139 Dimensional stability (-20℃, 48h) (%) -0.17 -0.22 -0.14 -0.15

[0070] Table 2 Components (parts by weight) and performance test results of comparative rigid polyurethane foam samples

[0071]

[0072]

[0073] All the raw materials of Example 3, Comparative Example 1 and Comparative Example 3 were taken respectively, sealed and placed at room temperature, and rigid polyurethane foam was prepared after a specified time. The relevant properties were tested as shown in Table 3.

[0074] Table 3 Performance test results of rigid polyurethane foam samples

[0075]

[0076] The rigid polyurethane foam prepared in Example 3 has good comprehensive properties. As the storage time increases, the reaction speed slows down and the thermal conductivity increases. Tertiary amine catalysts are used in Comparative Examples 1 and 3. Tertiary amine catalysts have strong nucleophilicity and are easy to react with double bonds and halogen atoms, which will reduce the long-term stability of the foaming agent in the foaming system. Compared with Comparative Examples 1 and 3, the rigid polyurethane foam of Example 3 has a slow increase in reaction speed and thermal conductivity after being placed at room temperature for 2 months, which can effectively improve the storage time of the foaming material.

[0077] The rigid polyurethane foam samples of Example 3 and Comparative Example 1 were used to produce energy-saving refrigerators of the same model, and the energy consumption of the whole machine was detected. The performance tests of the whole machine were all in accordance with national standards (GB / T8059-2016 Household and similar refrigeration appliances and GB12021.2-2015 Household refrigerators Power consumption limits and energy efficiency grades), and the results are shown in Table 4.

[0078] Table 4 Whole machine energy consumption test on a Hisense refrigerator product

[0079]

[0080] The rigid polyurethane foam sample of Example 3 is used to produce an energy-saving refrigerator. Compared with the rigid polyurethane foam sample of the same model using Comparative Example 1, the vacuum insulation panels are eliminated from the left and right boxes of the refrigerator product, and only the vacuum insulation panels are used on the back, and the area of ​​the vacuum insulation panels is reduced by 60%, and the energy consumption level of the products is similar. In view of the high price of vacuum insulation panels, compared with the sample of Comparative Example 1, which is provided with vacuum insulation panels on the back and both sides when producing an energy-saving refrigerator, Example 3 only has a vacuum insulation panel on the back to achieve the thermal insulation performance of Comparative Example 1, which has obvious cost advantages.

[0081] In summary, the foaming agent 2-chloro-3,3,3-trifluoropropene (HFO-1233xf) is used in the environmentally friendly rigid polyurethane foam component of the present invention, and its ODP is equal to 0, the GWP value is low, it is non-flammable, environmentally friendly, and has good environmental protection. It works synergistically with specific catalysts and foam stabilizers, has better foam storage stability, better low-temperature dimensional stability, and has better environmental protection and safety than the cyclopentane system, and meets the requirements of domestic and foreign environmental protection regulations and the needs of future development. The environmentally friendly rigid polyurethane foam prepared by the present invention has fine and uniform pores, has excellent thermal conductivity, and can make the product more energy-saving; has good aging performance, can accelerate the demoulding speed of polyurethane foam, and improve the efficiency of product foaming production; can be stored for a long time to ensure the stability of production; has excellent thermal insulation performance, can replace part of the vacuum insulation board, and has obvious cost advantages when used in energy-saving refrigerators; and the preparation method does not require technical transformation of existing equipment, and is suitable for large-scale production.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. An environmentally friendly rigid polyurethane foam, characterized in that: The composition comprises the following components by weight: 95-100 parts of polyol, 1.8-2.5 parts of foam stabilizer, 1.5-2.3 parts of catalyst, 15-30 parts of foaming agent, 130-150 parts of organic isocyanate and 1.5-2.3 parts of water; The foam stabilizer is a silicon foam stabilizer containing a Si-C structure; The catalyst includes a foaming catalyst, a gel catalyst and a trimerization catalyst; The foaming agent is 2-chloro-3,3,3-trifluoropropene.

2. The environmentally friendly rigid polyurethane foam according to claim 1, characterized in that: The polyol comprises polyether polyol A, polyether polyol B, polyether polyol C and polyester polyol; the mass ratio of polyether polyol A, polyether polyol B, polyether polyol C and polyester polyol is (25-35):(25-35):(15-25):(10-20); The polyether polyol A has an average functionality of 6.0 and a hydroxyl value of 400 to 480 mgKOH / g; The polyether polyol B has an average functionality of 3.7 and a hydroxyl value of 330 to 420 mgKOH / g; The polyether polyol C has an average functionality of 4.9 and a hydroxyl value of 400 to 450 mgKOH / g; The polyester polyol has an average functionality of 2.8 and a hydroxyl value of 250 to 350 mgKOH / g.

3. The environmentally friendly rigid polyurethane foam according to claim 2, characterized in that: The polyester polyol is an aromatic polyester polyol.

4. The environmentally friendly rigid polyurethane foam according to claim 1, characterized in that: The foam stabilizer is an organosiloxane polyoxyalkylene graft copolymer.

5. The environmentally friendly rigid polyurethane foam according to claim 1, characterized in that: The foaming catalyst is N-methylcyclohexylamine; the gelling catalyst is dimethylcyclohexylamine; and the trimerization catalyst is (2-hydroxypropyl)trimethylammonium formate.

6. The environmentally friendly rigid polyurethane foam according to claim 5, characterized in that: The mass ratio of the foaming catalyst, the gelling catalyst and the trimerization catalyst is (0.4-0.8):(0.3-1.2):(0.2-0.8).

7. The environmentally friendly rigid polyurethane foam according to claim 1, characterized in that: The organic isocyanate is polymethylene polyphenyl polyisocyanate, the viscosity of which is 350mPa.s-500mPa.s and the isocyanate content is 30.5%-32%.

8. The method for preparing the environmentally friendly rigid polyurethane foam according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1: uniformly mixing the polyol, foam stabilizer, catalyst and water according to the weight proportions to obtain a first mixture; S2: uniformly mixing the first mixture with the foaming agent to obtain a second mixture; S3: The second mixture and the organic polyisocyanate are mixed under high pressure through a foaming gun head and injected into the foaming cavity for mixing and foaming.

9. The preparation method according to claim 8, characterized in that: The steps S1 to S2 are performed at a material temperature of 15°C to 25°C; the step S3 is performed at a material temperature of 15°C to 20°C; the foaming cavity is preheated at 35°C to 45°C, and the gun tip pressure of the foaming gun is 110 bar to 160 bar.

10. Use of the environmentally friendly rigid polyurethane foam according to any one of claims 1 to 7 in the field of household appliances.

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