A method of making a rigid polyurethane foam

Abstract

The application discloses a preparation method of rigid polyurethane foam. The rigid polyurethane foam is prepared from a polyol composition, a physical foaming agent and an organic isocyanate; the polyol composition contains a silicon-containing foam stabilizer S1 with a mass ratio of greater than or equal to 1.8 wt%; the surface tension of the silicon-containing foam stabilizer S1 is less than 25.0 mN / m; the physical foaming agent contains cyclopentane, and the amount of cyclopentane is greater than 11 parts per 100 parts of the polyol composition; and the preparation method comprises the following steps: mixing 100 parts of the polyol composition with less than or equal to 14 parts of cyclopentane to obtain component I; mixing the remaining physical foaming agent with the organic isocyanate to obtain component II; and mixing the component I and the component II to obtain the rigid polyurethane foam. The preparation method is simple and stable, and can obtain the rigid polyurethane foam with low density and low thermal conductivity in an alkane system.

Description

Technical Field

[0001] This invention belongs to the field of polymer chemistry technology, and specifically relates to a method for preparing rigid polyurethane foam. Background Technology

[0002] Rigid polyurethane foam is a high-performance thermal insulation material widely used in building energy conservation, refrigerators, freezers, containers, and other fields. Thermal conductivity is the main indicator for judging insulation performance. Thermal conductivity is mainly composed of several factors: gas phase thermal conductivity, solid phase thermal conductivity, radiative heat transfer thermal conductivity, and convective heat transfer thermal conductivity. Among these, gas phase thermal conductivity has the highest influence, followed by radiative heat transfer thermal conductivity and solid phase thermal conductivity. The level of gas phase thermal conductivity mainly depends on the type of blowing agent used. For example, cyclopentane has a gas phase thermal conductivity of 12.0 mW / (m·K), while 1-chloro-3,3,3-trifluoropropylene (LBA) has a gas phase thermal conductivity of 10.2 mW / (m·K). LBA with low thermal conductivity has been phased out; therefore, the industry currently mainly uses alkane blowing agent systems. However, due to the high gas phase thermal conductivity of alkanes, the optimization space for the thermal conductivity of the resulting rigid polyurethane foam is limited, and a reduction of a few tenths is considered a significant improvement.

[0003] Typically, rigid polyurethane foams using alkane-based blowing agents have a thermal conductivity >19.0 mW / (m·K). For example, CN1908028A discloses a low-density, low-thermal-conductivity rigid polyurethane foam, which uses cyclopentane and isopentane as the main blowing agent components. Through the synergistic effect of raw materials such as sucrose polyether and methyl glucoside polyether, the resulting polyurethane foam has a thermal conductivity of 19.6~21.1 mW / (m·K). Another example is CN101948563A, which discloses pentane-type composite polyethers and compositions containing them, rigid polyurethane foams, and their applications. Through further optimization of the composite polyether components, the resulting rigid polyurethane foam has a thermal conductivity of 19.0~19.5 mW / (m·K).

[0004] To further reduce the thermal conductivity of polyurethane foam, existing technologies have also optimized it by developing new foaming agents. For example, CN118307832A discloses a physical foaming agent composition and a method for preparing rigid polyurethane foam using it. Tetramethylsilane is used as a new physical foaming agent component and is used in combination with alkane compounds to achieve the effect of optimizing the thermal conductivity. However, tetramethylsilane is expensive and not commonly used.

[0005] Given the various problems with the aforementioned technologies and considering current environmental requirements, the rigid polyurethane foam industry still needs a foaming technology that is easy to operate, cost-effective, and uses environmentally friendly raw materials. This technology should not use fluorinated compounds or low-boiling-point silane-based novel foaming agents, and should be able to produce rigid polyurethane foam with excellent thermal insulation properties. In particular, to reduce fossil fuel consumption, it is necessary to produce polyurethane materials with lower density while still maintaining low thermal conductivity and superior overall foam performance. Summary of the Invention

[0006] Objective of the Invention: The objective of this invention is to provide a method for preparing rigid polyurethane foam. The preparation method of this invention uses an alkane-based foaming agent system and combines a foam stabilizer with specific surface tension and a specific preparation method to optimize the thermal conductivity of the rigid polyurethane foam.

[0007] Technical solution: The objective of this invention is achieved through the following technical solution: This invention provides a method for preparing rigid polyurethane foam, wherein the rigid polyurethane foam is prepared from a polyol composition, a physical blowing agent, and an organic isocyanate; the polyol composition contains ≥1.8 wt% of a silicone foam stabilizer S1, wherein the surface tension of the silicone foam stabilizer S1 is <25.0 mN / m; the physical blowing agent contains cyclopentane, and by weight, per 100 parts of the polyol composition, cyclopentane >11 parts; the preparation method includes the following steps: (1) Mix 100 parts of the polyol composition with ≤14 parts of cyclopentane to obtain component I; (2) Mix the remaining physical foaming agent with the organic isocyanate to obtain component II; (3) Mix component I and component II to obtain rigid polyurethane foam.

[0008] This invention utilizes a silicone-containing foam stabilizer S1 with suitable surface tension, along with specific operational steps, to optimize the thermal conductivity of rigid polyurethane foam at low densities. Studies have shown that silicone-containing foam stabilizer S1 with a surface tension <25.0 mN / m can be better dispersed in the polyol composition, thus better optimizing the cell structure. However, there is a negative impact of poor compatibility between alkane compounds in physical blowing agents and silicone-containing foam stabilizer S1, especially when the mass percentage of silicone-containing foam stabilizer S1 in the polyol composition is ≥1.8 wt%, highlighting the incompatibility and hindering the stability of the material system and the nucleation process. However, studies have also found that a specific mixing step can solve the above problems and is beneficial for the formation and distribution of closed cells. This specific mixing step involves mixing cyclopentane with a polyol composition containing a high mass percentage of silicone-containing foam stabilizer S1, with ≤14 parts of cyclopentane added per 100 parts of the polyol composition.

[0009] The silicone-containing foam stabilizer S1 described in this invention is a polyether-modified organosilicon surfactant for rigid foam that has emulsifying and nucleating effects. It has a high boiling point, is in the liquid phase during polyurethane reactions, and contains both polysiloxane and polyoxyolefin segments, typically exhibiting a Si-C type chain structure. Preferably, the silicone-containing foam stabilizer S1 is a polyether-polyalkylsiloxane copolymer with a surface tension <25.0 mN / m.

[0010] Furthermore, in order to obtain a better thermal conductivity optimization effect, the surface tension of the silicon-containing foam stabilizer S1 is preferably greater than 23mN / m and less than 25mN / m, such as 23.5~24.5mN / m.

[0011] In the preparation of rigid polyurethane foam, hydroxyl-containing components and isocyanate-containing components are typically reacted in the presence of a blowing agent. The material ratio is determined according to the target characteristics of the rigid polyurethane foam, as long as a rigid polyurethane foam that meets the density and other requirements can be produced. The raw material ratio of rigid polyurethane foam is usually calculated based on 100 parts of polyol composition. In order to obtain a lower density, this invention requires more than 11 parts of cyclopentane to match every 100 parts of polyol composition. Furthermore, the total amount of cyclopentane required per 100 parts of polyol composition is preferably 11.5 to 18.0 parts.

[0012] Conventional hydroxyl-containing components in the art are polyol compositions, which are mixtures containing polyether polyols and / or polyester polyols, catalysts, foam stabilizers, water, etc., and may also include appropriate additives such as colorants, flame retardants, and fillers as needed. In the polyol composition of this invention, only the foam stabilizer differs from conventional ones; the other components are all conventional in the art.

[0013] The polyol composition of this invention contains polyether polyol and / or polyester polyol, catalyst, foam stabilizer S, and water. The foam stabilizer S may contain, in addition to silicone-containing foam stabilizer S1, other conventional foam stabilizers, such as foam stabilizer S2 with a surface tension ≥25.0 mN / m.

[0014] Specifically, the proportion of foam stabilizer S in the polyol composition is 2.0~5.0 wt%, the proportion of water is 1.7~2.7 wt%, the proportion of catalyst is 2.0~6.0 wt%, and the balance is polyether polyol and / or polyester polyol.

[0015] More specifically, according to the composition of the foam stabilizer S, the polyol composition contains 1.8 to 5.0 wt% of silicone foam stabilizer S1, 0 to 2.0 wt% of foam stabilizer S2, 1.7 to 2.7 wt% of water, 2.0 to 6.0 wt% of catalyst, and the balance is polyether polyol and / or polyester polyol.

[0016] In a preferred embodiment of the present invention, the polyol composition contains polyether polyol and / or polyester polyol, catalyst, silicone foam stabilizer S1 and water, and the average hydroxyl value of the anhydrous polyol composition is 330~470 mgKOH / g.

[0017] Further preferably, the polyol composition comprises 2.0–5.0 wt% of silicone foam stabilizer S1, 1.7–2.7 wt% of water, 2.0–6.0 wt% of catalyst, and the balance being polyether polyol and / or polyester polyol. To better match the material system, the anhydrous average hydroxyl value of the polyol composition of the present invention is 330–470 mg KOH / g.

[0018] The polyether polyol is typically prepared by ring-opening polymerization of an oxidized olefin component with a compound containing active hydrogen (such as polyol and / or polyamine) as an initiator. The initiator can be selected from sucrose, sorbitol, mannitol, diethylene glycol, trimethylolpropane, glycerol, pentaerythritol, alkanolamines, aromatic amines, alicyclic amines, etc.

[0019] Polyester polyols are typically formed by the condensation of organic dicarboxylic acids (anhydrides or esters) with small-molecule polyols (including diols) or by the polymerization of lactones with polyols. The dicarboxylic acids (anhydrides or esters) can be selected from phthalic anhydride, terephthalic acid or dimethyl terephthalate, adipic acid, etc., while the small-molecule polyols can be selected from ethylene glycol, propylene glycol, butanediol, propylene glycol monohydrate, trimethylolpropane, pentaerythritol, hexanediol, etc.

[0020] The catalyst used in this invention is for catalyzing reactions involving isocyanate groups to catalyze the formation of carbamate, urea, or isocyanurate bonds. Conventional types in the art can be used, and the catalyst can be selected from any one or more of pentamethyldiethylenetriamine, bis(dimethylaminoethyl) ether, tetramethylhexamethylenediamine, dibutyltin dilaurate, N-ethylmorpholine, N,N-dimethylcyclohexylamine, triethylenediamine, 1,2-dimethylimidazolium, dimethylbenzylamine, 1,3,5-tris(dimethylaminopropyl)hexahydrotriazine, 2,4,6-tris(dimethylaminomethyl)phenol, quaternary ammonium salts, potassium octanoate, potassium 2-ethylhexanoate, potassium acetate, (2-hydroxypropyl)trimethylammonium formate, ethyl quaternary ammonium salts, and octyl quaternary ammonium salts. When two or more catalysts are used, they can be mixed in any proportion.

[0021] Furthermore, the preparation method of the present invention is also applicable to material systems with higher water content to obtain lower foam density. The water content of the polyol composition can be as high as 2.7 wt%, with a wide range of water content adjustment. For example, if the water content of the polyol composition is 1.7~2.7 wt%, under the same amount of foaming agent and material ratio, it can be 2.2~2.7 wt% when lower density is required.

[0022] For low-density rigid polyurethane foam, one of the main factors affecting its density is the total amount of blowing agents used, including physical and chemical blowing agents, with water being the chemical blowing agent. Therefore, this invention can prepare lower-density rigid polyurethane foam by increasing the amount of physical and / or chemical blowing agents, thereby reducing the consumption of petrochemical resources while still meeting usage requirements.

[0023] The physical blowing agent of this invention is mainly composed of alkane compounds, that is, the mass proportion of alkane compounds in the physical blowing agent is >88%. Besides alkane compounds, any other environmentally friendly blowing agent in the art can be used to achieve certain functionalities, such as fluoroolefin compounds such as monofluoroolefins, trifluoroolefins, pentafluoroolefins, and hexafluoroolefins that have not yet been phased out or replaced. To balance environmental friendliness and process convenience, the physical blowing agent of this invention is preferably 100% alkane compounds, that is, it does not contain other non-alkane physical blowing agents, or preferably alkane compounds and a small amount (<12%) of fluoroolefin compounds. The alkane compounds can be selected from hydrocarbons with 3 to 5 carbon atoms, such as propane, n-butane, isobutane, cyclopentane, n-pentane, isopentane, and neopentane.

[0024] To improve compatibility with material systems, the physical blowing agent is composed of cyclopentane and at least one of n-butane, isobutane, propane, isopentane, n-pentane, or neopentane.

[0025] According to conventional practice in the art, the physical foaming agent is usually added entirely to the polyol composition for premixing to obtain a white component with suitable viscosity. However, the applicant found that this method is not suitable for material systems using silicone foam stabilizer S1. Therefore, the preparation method was optimized by reducing the mixing amount of cyclopentane and polyol components to fully utilize the optimizing effect of silicone foam stabilizer S1 on bubble formation and stabilization. Considering the further consideration of flowability, the amount of cyclopentane added should not be too low. Therefore, in step (1), 11 to 14 parts of cyclopentane are mixed for every 100 parts of polyol composition.

[0026] In order to balance the flowability and stability of component I obtained in step (1), the material temperature of component I is preferably 16~28℃.

[0027] In step (2) of this invention, the residual physical blowing agent containing cyclopentane is mixed with an organic isocyanate. This residual physical blowing agent containing cyclopentane can be solely the residual cyclopentane, or it can be a mixture of the residual cyclopentane with other non-cyclopentane compounds, such as a mixture of the residual cyclopentane with at least one of isopentane, n-butane, isobutane, propane, isopentane, n-pentane, or neopentane. To achieve uniform mixing with component I of this invention, the feed temperature of component II is preferably 10-21°C.

[0028] Conventional organic isocyanates in the art can be used in this invention, including polymethylene polyphenyl polyisocyanate (abbreviated as polymeric MDI) and / or modified isocyanates.

[0029] Preferably, the organic isocyanate has an NCO% of 25-32 wt% and an average functionality > 2.5, such as 2.56-3.0, to further balance crosslinking density and improve foam strength. Considering the safety and convenience of raw material use, the organic isocyanate can be selected from polymeric MDI, with an NCO% of 30.0-32.0% and an average functionality of 2.6-3.0, such as Wannate. ® PM200, Desmodur ® 44v20L, Lupranate ® M20s, Wannate ® PM2010, Lupranate ® M50, Wannate ® PM400, Desmodur ® 44V40L, Suprasec ® 2085, PAPI TM Any of the 580N models.

[0030] To further optimize thermal conductivity, organic isocyanates may contain modified isocyanates, such as modified isocyanates or mixtures of modified isocyanates and polymeric MDI. When using only modified isocyanates as organic isocyanates, those with NCO% ≥ 25 wt% and average functionality > 2.5 are typically selected; for modified isocyanates with NCO% < 25 wt%, they can be mixed with polymeric MDI with NCO% ≥ 30 wt% and average functionality > 2.6. Modified isocyanates generally refer to substances prepared by reacting polyols with toluene diisocyanate, diphenylmethane diisocyanate, and / or polymethylene polyphenyl polyisocyanate, such as modified isocyanates with NCO% = 18~28 wt% and average functionality 2.0~2.6. Conventional polyols in the field can be used.

[0031] The amount of the organic isocyanate used can be within the conventional range in the art, and is usually determined according to the isocyanate index. The isocyanate index refers to the molar amount of reactive groups (i.e., NCO groups) in the organic isocyanate to the molar amount of reactive groups (i.e., OH groups) in the polyol composition. The isocyanate index of the present invention can be 1.03~1.4, that is, the molar amount of reactive groups of the organic isocyanate to the molar amount of reactive groups of the polyol composition is 1.03~1.4. Based on this, the preferred mass ratio of the raw materials in the present invention is polyol composition: physical foaming agent: organic isocyanate = 100:(15~21):(115~175).

[0032] Beneficial effects: The preparation method of this invention is simple and has good stability, and can obtain alkane-based rigid polyurethane foam with low density and low thermal conductivity. Detailed Implementation

[0033] The technical solution of the present invention will be described in detail below through specific embodiments, but the scope of protection of the present invention is not limited to the embodiments described.

[0034] The raw materials used in this invention are as follows: VORANOL, a sucrose-based polyether polyol TM 550, hydroxyl value 550 mg KOH / g, functionality 4.9, Dow Chemical; sucrose-based polyether polyol VORANOL TM 490, hydroxyl value 490 mg KOH / g, functionality 4.3, Dow Chemical; Trimethylolpropane polyether polyol PLURACOL ® TP440, hydroxyl value 398 mgKOH / g, functionality 3.0, BASF; Glyceryl polyether polyol H303, hydroxyl value 560mgKOH / g, functionality 3.0, Hongbaoli Group; Glyceryl polyether polyol H307, hydroxyl value 240mgKOH / g, functionality 3.0, Hongbaoli Group; Sorbitol-based polyether polyol H5021, hydroxyl value 370mgKOH / g, functionality 4.6, Hongbaoli Group; PLURACOL (Aromatic Amine Polyether Polyol) ® 1168, hydroxyl value 300 mg KOH / g, functionality 4.0, BASF; PLURACOL (Aromatic Amine Polyether Polyol) ® 736, hydroxyl value 390 mg KOH / g, functionality 4.0, BASF; Phthalic anhydride polyester polyol STEPANPOL ® PS-2602, hydroxyl value 260mgKOH / g, functionality 2.0, Stepan.

[0035] Silicone foam stabilizer S1: The polyether-modified silicone surfactants HB016 (surface tension 23.7 mN / m), HB18 (surface tension 24.0 mN / m), and HB23 (surface tension 23.5 mN / m) were all purchased from Meiside. The polyether-modified silicone surfactant HB21, with a surface tension of 24.5 N / m, was purchased from Evonik.

[0036] Foam stabilizer S2: The polyether-modified silicone surfactant HB012, with a surface tension of 25.5 mN / m, was purchased from Momentive. The polyether-modified silicone surfactant HB003, with a surface tension of 25.0 mN / m, was purchased from Meiside.

[0037] Other foam stabilizers: F-242T, a polyether-modified silicone surfactant with a surface tension of 21.5 mN / m, is produced by Shin-Etsu Chemical.

[0038] Nucleating agent: tetrafluoroethyl ether, surface tension 14.7 mN / m, Myriel.

[0039] The composite catalyst is a mixture of pentamethyldiethylenetriamine, N,N-dimethylcyclohexylamine and 1,3,5-tris(dimethylaminopropyl)hexahydrotriazine in a mass ratio of 1:4.6:1.5.

[0040] Lupranate (polymethylene polyphenyl polyisocyanate) ® M20s, nominal NCO% 31.5%, nominal functionality 2.7, BASF; PAPI (polymethylene polyphenyl polyisocyanate)TM 580N, nominal NCO% 30.8%, nominal functionality 3.0, Dow Chemical; Modified isocyanate ISO-1#, homemade, using aromatic polyester polyol Stepanpol® PS-2602 and diethylene glycol polyether polyol VORANOL in a mass ratio of 1:9. TM 220-110 Modified Lupranate ® It was prepared by M20s, with NCO%=25% and an average functionality of 2.56; The modified isocyanate A is prepared by vacuum dehydrating a hydroxyl-containing compound and then reacting it with an organic isocyanate at 40~70℃. The modified isocyanate A is obtained after the reaction is complete.

[0041] The present invention characterizes its physicochemical properties using the following methods: Surface tension was determined according to the method in GB / T 22237-2008 Surfactants—Determination of Surface Tension; water content and hydroxyl value were determined according to the method in HG / T 4961-2016 Polyurethane Rigid Foam Polyether Composites for Refrigerators and Freezers. The law shall be followed; Core density, dimensional stability, thermal conductivity, and compressive strength all comply with GB / T 26689-2011 Refrigerators and Freezers. The method described in "Rigid Polyurethane Foam" was used. The method for determining the NCO mass fraction was carried out in accordance with the method in GB / T 12009.4-2016 Aromatic Isocyanates for Polyurethane Production - Part 4: Determination of Isocyanate Content. Density distribution uniformity: The uniformity of density distribution after the mold is fully filled is examined. The mold size is 1200mm×400mm×70mm. The core density range is used to represent the density distribution uniformity, which is the difference between the maximum and minimum core density measured at different sampling points on the same sample.

[0042] The material composition of the polyol composition used in this invention is shown in Table 1: Table 1. Formulation composition of polyol compositions (parts by weight)

[0043] Example 1 Use the polyol composition A-1# from Table 1, and follow the raw material ratio of A-1#:cyclopentane:Lupranate. ® M20s=100:17:118 Prepare raw materials and prepare rigid polyurethane foam according to the following steps: S1) Mix 100 parts of the polyol composition with 14 parts of cyclopentane to obtain component I-1#, with a material temperature of 28℃; S2) The remaining cyclopentane is reacted with Lupranate ® M20s were mixed to obtain component II-1# at a material temperature of 21℃; S3) Mix components I-1# and II-1# in a high-pressure foaming machine and inject the mixture into a mold at a temperature of 35-40°C. After the reaction product is cured and molded, rigid polyurethane foam is obtained, which is denoted as PU-1#. Example

[0044] Use the A-2# polyol composition from Table 1, and follow the raw material ratio of A-2#:cyclopentane:n-butane:Lupranate. ® M20s=100:18:3:149 Prepare raw materials and prepare rigid polyurethane foam according to the following steps: S1) Mix 100 parts of the polyol composition with 14 parts of cyclopentane to obtain component I-2#, with a material temperature of 18℃; S2) Combine n-butane, the balance cyclopentane, and Lupranate ® M20s were mixed to obtain component II-2# at a material temperature of 16℃; S3) Mix components I-2# and II-2# in a high-pressure foaming machine and inject the mixture into a mold at a temperature of 35-40°C. After the reaction product is cured and molded, rigid polyurethane foam is obtained, which is denoted as PU-2#. Example

[0045] Use the polyol composition A-3# from Table 1, and follow the raw material ratio of A-3#:cyclopentane:isopentane:PAPI. TM Prepare raw materials and prepare rigid polyurethane foam according to the following steps: 580N=100:11.5:4.5:171 S1) Mix 100 parts of the polyol composition with 11.5 parts of cyclopentane to obtain component I-3#, with a material temperature of 18℃; S2) Reaction of isopentane with PAPI TM Mix with 580N to obtain component II-3# at a material temperature of 18℃; S3) Mix components I-3# and II-3# in a high-pressure foaming machine and inject the mixture into a mold at a temperature of 35-40°C. After the reaction product is cured, rigid polyurethane foam is obtained, which is denoted as PU-3#. Example

[0046] Use the A-4# polyol composition from Table 1, and follow the raw material ratio of A-4#:cyclopentane:trifluoropropylene:Lupranate. ®M20s=100:14:1:137 Prepare raw materials and prepare rigid polyurethane foam according to the following steps: S1) Mix 100 parts of the polyol composition with 12 parts of cyclopentane to obtain component I-4#, with a material temperature of 16℃; S2) Trifluoropropylene, the balance cyclopentane and Lupranate ® M20s were mixed to obtain component II-4# at a material temperature of 16℃; S3) Mix components I-4# and II-4# in a high-pressure foaming machine and inject the mixture into a mold at a temperature of 35-40°C. After the reaction product is cured, rigid polyurethane foam is obtained, which is denoted as PU-4#. Example

[0047] Use the A-5# polyol composition from Table 1, and follow the raw material ratio of A-5#:cyclopentane:n-pentane:Lupranate. ® M20s=100:17:2:152 Prepare raw materials and prepare rigid polyurethane foam according to the following steps: S1) Mix 100 parts of the polyol composition with 13 parts of cyclopentane to obtain component I-5#, with a material temperature of 18℃; S2) Mix n-pentane, the balance cyclopentane, and Lupranate ® M20s were mixed to obtain component II-5# at a material temperature of 21℃; S3) Mix components I-5# and II-5# in a high-pressure foaming machine and inject the mixture into a mold at a temperature of 35-40°C. After the reaction product is cured, rigid polyurethane foam is obtained, which is denoted as PU-5#. Example

[0048] Use the A-6# polyol composition from Table 1, and follow the raw material ratio of A-6#:cyclopentane:trifluoropropylene:Lupranate. ® M20s=100:16:1:134 Prepare raw materials and prepare rigid polyurethane foam according to the following steps: S1) Mix 100 parts of the polyol composition with 12 parts of cyclopentane to obtain component I-6#, with a material temperature of 16℃; S2) Trifluoropropylene, the balance cyclopentane and Lupranate ® M20s were mixed to obtain component II-6# at a material temperature of 16℃; S3) Mix components I-6# and II-6# in a high-pressure foaming machine and inject the mixture into a mold. The mold temperature is 35-40℃. After the reaction product is cured and molded, rigid polyurethane foam is obtained, which is denoted as PU-6#. Example

[0049] Use the A-7# polyol composition from Table 1, and follow the raw material ratio of A-7#:cyclopentane:n-butane:Lupranate. ® M20s=100:18:3:152 Prepare raw materials and prepare rigid polyurethane foam according to the following steps: S1) Mix 100 parts of the polyol composition with 14 parts of cyclopentane to obtain component I-7#, with a material temperature of 18℃; S2) Combine n-butane, the balance cyclopentane, and Lupranate ® M20s were mixed to obtain component II-7# at a material temperature of 16℃; S3) Mix components I-7# and II-7# in a high-pressure foaming machine and inject the mixture into a mold at a temperature of 35-40°C. After the reaction product is cured and molded, rigid polyurethane foam is obtained, which is denoted as PU-7#. Example

[0050] Use the A-2# polyol composition from Table 1, and follow the raw material ratio of A-2#:cyclopentane:propane:Lupranate. ® M20s=100:18:2:148 Prepare raw materials and prepare rigid polyurethane foam according to the following steps: S1) Mix 100 parts of the polyol composition with 13 parts of cyclopentane to obtain component I-8#, with a material temperature of 21℃; S2) Mix propane, the balance cyclopentane, and Lupranate ® M20s were mixed to obtain component II-8# at a material temperature of 10℃; S3) Mix components I-8# and II-8# in a high-pressure foaming machine and inject the mixture into a mold at a temperature of 35-40°C. After the reaction product is cured, rigid polyurethane foam is obtained, which is denoted as PU-8#. Example

[0051] Use the A-2# polyol composition from Table 1, and follow the raw material ratio of A-2#:cyclopentane:hexafluoropropylene:Lupranate. ® M20s=100:16:2:150. Prepare raw materials and prepare rigid polyurethane foam according to the following steps: S1) Mix 100 parts of the polyol composition with 12 parts of cyclopentane to obtain component I-9#, with a material temperature of 21℃; S2) Hexafluoropropylene, the balance cyclopentane and Lupranate ® M20s were mixed to obtain component II-9# at a material temperature of 10℃; S3) Mix components I-9# and II-9# in a high-pressure foaming machine and inject the mixture into a mold at a temperature of 35-40°C. After the reaction product is cured, rigid polyurethane foam is obtained, which is denoted as PU-9#. Example

[0052] Using the A-2# polyol composition in Table 1, and preparing the raw materials according to the ratio A-2#:cyclopentane:isobutane:ISO-1#=100:16:2:174, rigid polyurethane foam was prepared according to the following steps: S1) Mix 100 parts of the polyol composition with 14 parts of cyclopentane to obtain component I-10#, with a material temperature of 25℃; S2) Isobutane, the balance cyclopentane and ISO-1# are mixed to obtain component II-10#, with a feed temperature of 12℃; S3) Mix components I-10# and II-10# in a high-pressure foaming machine and inject the mixture into a mold. The mold temperature is 35-40℃. After the reaction product is cured and molded, rigid polyurethane foam is obtained, which is denoted as PU-10#.

[0053] Comparative Example 1 Use the D-1# polyol composition from Table 1, and follow the raw material ratio of D-1#:cyclopentane:n-butane:Lupranate. ® M20s=100:18:3:149 Prepare raw materials and prepare rigid polyurethane foam according to the following steps: S1) Mix 100 parts of the polyol composition with 14 parts of cyclopentane to obtain component I-D1#, with a material temperature of 18℃; S2) Combine n-butane, the balance cyclopentane, and Lupranate ® M20s were mixed to obtain component II-D1# at a material temperature of 16℃; S3) Mix components I-D1# and II-D1# in a high-pressure foaming machine and inject the mixture into a mold at a temperature of 35-40°C. After the reaction product is cured and molded, rigid polyurethane foam is obtained, which is denoted as PU-D1#.

[0054] Comparative Example 2 Use the D-2# polyol composition from Table 1, and follow the raw material ratio of D-2#:cyclopentane:n-butane:Lupranate. ® M20s=100:18:3:149 Prepare raw materials and prepare rigid polyurethane foam according to the following steps: S1) Mix 100 parts of the polyol composition with 14 parts of cyclopentane to obtain component I-D2# at a material temperature of 18°C; S2) Combine n-butane, the balance cyclopentane, and Lupranate ®M20s were mixed to obtain component II-D2# at a material temperature of 16℃; S3) Mix components I-D2# and II-D2# in a high-pressure foaming machine and inject the mixture into a mold at a temperature of 35-40°C. After the reaction product is cured, rigid polyurethane foam is obtained, denoted as PU-D2#.

[0055] Comparative Example 3 Use the D-3# polyol composition from Table 1, and follow the raw material ratio of D-3#:cyclopentane:n-butane:Lupranate. ® M20s=100:18:3:149 Prepare raw materials and prepare rigid polyurethane foam according to the following steps: S1) Mix 100 parts of the polyol composition with 14 parts of cyclopentane to obtain component I-D3# at a material temperature of 18°C; S2) Combine n-butane, the balance cyclopentane, and Lupranate ® M20s were mixed to obtain component II-D3# at a material temperature of 16℃; S3) Mix components I-D3# and II-D3# in a high-pressure foaming machine and inject the mixture into a mold at a temperature of 35-40°C. After the reaction product is cured and molded, rigid polyurethane foam is obtained, which is denoted as PU-D3#.

[0056] Comparative Example 4 Use the D-4# polyol composition from Table 1, and follow the raw material ratio of D-4#:cyclopentane:Lupranate. ® M20s=100:17:118 Prepare raw materials and prepare rigid polyurethane foam according to the following steps: S1) Mix 100 parts of the polyol composition with 14 parts of cyclopentane to obtain component I-D4# at a material temperature of 28°C; S2) The remaining cyclopentane is reacted with Lupranate ® M20s were mixed to obtain component II-D4# at a material temperature of 21℃; S3) Mix components I-D4# and II-D4# in a high-pressure foaming machine and inject the mixture into a mold at a temperature of 35-40°C. After the reaction product is cured, rigid polyurethane foam is obtained, which is denoted as PU-D4#.

[0057] Comparative Example 5 Use the polyol composition A-1# from Table 1, and follow the raw material ratio of A-1#:cyclopentane:Lupranate. ® M20s=100:17:118 Prepare raw materials and prepare rigid polyurethane foam according to the following steps: S1) Mix 100 parts of the polyol composition with 10 parts of cyclopentane to obtain component I-D5# at a material temperature of 28°C; S2) The remaining cyclopentane is reacted with Lupranate ® M20s were mixed to obtain component II-D5# at a material temperature of 21℃; S3) Mix components I-D5# and II-D5# in a high-pressure foaming machine and inject the mixture into a mold at a temperature of 35-40°C. After the reaction product is cured, rigid polyurethane foam is obtained, which is denoted as PU-D5#.

[0058] Comparative Example 6 Use the polyol composition A-1# from Table 1, and follow the raw material ratio of A-1#:cyclopentane:Lupranate. ® M20s=100:17:118 Prepare raw materials and prepare rigid polyurethane foam according to the following steps: S1) Mix 100 parts of the polyol composition with 17 parts of cyclopentane to obtain component I-D6# at a material temperature of 28°C; S2) Lupranate ® The material temperature of M20s is adjusted to 21℃; S3) Components I-D6# and Lupranate ® After being mixed in a high-pressure foaming machine, M20s are injected into a mold at a temperature of 35-40°C. The reaction product is then cured and molded to obtain rigid polyurethane foam, denoted as PU-D6#.

[0059] The properties of the prepared rigid polyurethane foam were characterized, and the results are shown in Tables 2 and 3.

[0060] Table 2 Performance characterization results of rigid polyurethane foam

[0061] Table 3 Performance characterization results of rigid polyurethane foam

[0062] As can be seen from the data in the table, this invention can produce rigid polyurethane foam with low thermal conductivity without using novel low-boiling-point silane foaming agents or restricted foaming agents such as LBA. Simultaneously, it can consider other foam properties and has a wide density control range, meeting the needs of different end-use applications. Comparative Examples 1 to 4, when using foam stabilizers different from those of this invention, all exhibited different levels of performance degradation. In particular, Comparative Example 4 used a foam stabilizer with lower surface tension, resulting in increased open cells, decreased foam closed-cell ratio, and consequently increased thermal conductivity, while also exhibiting poor compressive strength and flowability. Comparative Examples 5 and 6 used different amounts of cyclopentane in step (1) than those of this invention. Comparative Example 5 had a smaller amount of cyclopentane mixed with the polyol component, resulting in poor flowability. Comparative Example 6 had a larger amount of cyclopentane mixed with the polyol component, which was detrimental to the stability of the material system and the nucleation process, resulting in higher core density and thermal conductivity.

[0063] As described above, although the invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the invention itself. Various changes in form and detail may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A method for preparing rigid polyurethane foam, characterized in that, The rigid polyurethane foam is prepared from a polyol composition, a physical blowing agent, and an organic isocyanate; the polyol composition contains a silicone foam stabilizer S1, the surface tension of which is <25.0 mN / m; the physical blowing agent contains cyclopentane, and by weight, cyclopentane >11 parts per 100 parts of the polyol composition; the preparation method includes the following steps: (1) Mix 100 parts of the polyol composition with ≤14 parts of cyclopentane to obtain component I; (2) Mix the remaining physical foaming agent with the organic isocyanate to obtain component II; (3) Mix component I and component II to obtain rigid polyurethane foam; The silicone-containing foam stabilizer S1 is a polyether-polyalkylsiloxane copolymer with a surface tension greater than 23 mN / m and less than 25 mN / m; the proportion of silicone-containing foam stabilizer S1 in the polyol composition is 1.8~5.0 wt%; the residual physical blowing agent is a residual physical blowing agent containing cyclopentane, which is either the remaining cyclopentane or a mixture of the remaining cyclopentane and other non-cyclopentane compounds.

2. The preparation method according to claim 1, characterized in that, The polyol composition contains polyether polyol and / or polyester polyol, catalyst, silicone foam stabilizer S1 and water, and the average hydroxyl value of the anhydrous polyol composition is 330~470 mgKOH / g.

3. The preparation method according to claim 1, characterized in that, The water content of the polyol composition is 1.7~2.7 wt%.

4. The preparation method according to claim 1, characterized in that, The physical foaming agent is composed of cyclopentane and at least one of n-butane, isobutane, propane, isopentane, n-pentane, or neopentane.

5. The preparation method according to claim 1, characterized in that, In step (1), 100 parts of the polyol composition are mixed with 11 to 14 parts of cyclopentane to obtain component I.

6. The preparation method according to claim 1, characterized in that, In step (1), the material temperature of component I is 16~28℃.

7. The preparation method according to claim 1, characterized in that, In step (2), the material temperature of component II is 10~21℃.

8. The preparation method according to claim 1, characterized in that, The organic isocyanate has an NCO% of 25-32 wt% and an average functionality > 2.

5.

9. The preparation method according to claim 1, characterized in that, The mass ratio of the polyol composition, physical foaming agent and organic isocyanate is 100:(15~21):(115~175).

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