Hard polyurethane electronic foam with high aperture ratio and preparation method thereof

Abstract

The invention belongs to the technical field of polymer foam materials, and particularly relates to rigid polyurethane electronic foam with high aperture ratio and a preparation method thereof. The hard polyurethane electronic foam is prepared from the following raw materials: a component A, namely a polyol mixture, a component B, namely isocyanate and a component C, namely expanded foaming microspheres. The foaming microspheres are introduced into the foam, and the curing temperature during foam preparation is controlled to be higher than the maximum expansion temperature of the foaming microspheres. The expanded foaming microsphere is a thermoplastic hollow polymer microsphere and is composed of a thermoplastic shell and sealed liquid alkane gas, the liquid alkane in the microsphere expands rapidly under the condition of high temperature, and when the heating temperature exceeds the maximum expansion temperature of the maximum expansion volume of the microsphere, the microsphere is broken, so that the expanded foaming microsphere is formed. Furthermore, more holes are formed in the surface and the interior of the foam, and the hole opening rate of the foam is increased.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer foaming materials, and more specifically, relates to a hard polyurethane electronic foam with a high open porosity and a preparation method thereof. Background Art

[0002] Microporous polyurethane rigid foam is a microporous foam material with high hardness. It is mainly made of PU resin and foaming agent through a special process. It has a fine pore structure, and the pore diameter can generally reach the micron level, so the material has a high specific surface area.

[0003] While remaining lightweight, the material has the following features:

[0004] 1. Microporous polyurethane rigid foam can maintain a good shape when under pressure, is not easy to deform, and can quickly return to its original state under high pressure;

[0005] 2. Microporous polyurethane rigid foam has high tensile strength, which enables the product to effectively resist damage from external forces during use and ensure the integrity of the product;

[0006] 3. Microporous polyurethane rigid foam has good weather resistance, can be used for a long time in various harsh environments, and is not easily affected by the external environment;

[0007] 4. Microporous polyurethane rigid foam does not contain harmful substances, meets environmental protection requirements and is safe to use;

[0008] 5. Microporous polyurethane rigid foam has good heat insulation and sound absorption properties, and can effectively reduce heat and sound transmission;

[0009] 6. Microporous polyurethane rigid foam has excellent energy absorption performance, which can absorb energy and reduce the damage to equipment and components caused by impact and vibration, thereby ensuring the stability and service life of the product;

[0010] Common applications of microcellular polyurethane rigid foam include:

[0011] 1. High-energy impact cushions and seals for mobile phones and tablets.

[0012] 2. Anti-vibration pads and sealing materials for aerospace equipment.

[0013] 3. Shock-absorbing pads and sound-insulating pads for medical equipment.

[0014] 4. Cushioning pads for sports shoe insoles and knee pads.

[0015] In short, microporous polyurethane foam has excellent properties, which makes it widely used in 3C industry (electronics, computers, communications), aerospace, medical, sports and other fields to solve the problems of product cushioning, sealing, shockproof, anti-slip, dustproof, sound insulation, sound absorption, shading, etc.

[0016] However, microporous polyurethane rigid foam has high density and hardness, and is easy to close the cells in the actual production process, resulting in foam shrinkage and reducing the production qualification rate of foam. To solve the shrinkage problem, the traditional method is to add a certain amount of modified silicone or polyether pore opening agent to increase the open porosity of the foam. Adding modified silicone or polyether pore opening agent sometimes cannot completely solve the shrinkage of the foam, and too much addition will have an adverse effect on the performance of the foam. In order to further improve the open porosity of the foam, the present invention provides another technical solution. Summary of the invention

[0017] In view of the defects of the prior art, the present invention provides a rigid polyurethane electronic foam with a high open porosity and a preparation method thereof, so as to solve the technical problems that the prior art adds modified silicone or polyether pore-opening agents to increase the open porosity of the foam, but cannot completely solve the shrinkage of the foam, and excessive addition will have an adverse effect on the performance of the foam.

[0018] To achieve the above object, the present invention provides a rigid polyurethane electronic foam with a high open porosity, the raw materials of which include a component A polyol mixture, a component B isocyanate and a component C expandable foaming microsphere; wherein,

[0019] The maximum expansion temperature of the expandable foamed microspheres of component C is ≤160°C;

[0020] The polyurethane electronic foam is obtained after the polyol of component A, the isocyanate of component B and the expandable foaming microspheres of component C are mixed and cured to form; and the curing temperature is greater than the maximum expansion temperature of the expandable foaming microspheres.

[0021] Preferably, the mass ratio of the polyol of component A, the isocyanate of component B and the expandable foaming microspheres of component C is 100:(40-70):(1-10).

[0022] Preferably, the polyol mixture of component A includes 50-80 parts by weight of high-functionality polyether polyol, 20-50 parts by weight of difunctionality polyether polyol, 0.5-2.5 parts by weight of surfactant, 0.5-3 parts by weight of pore opener, 0.1-1.0 parts by weight of catalyst, 0-3 parts by weight of small molecule active hydrogen compound, and 1-5 parts by weight of color paste. The isocyanate of component B includes one or more of diphenylmethane diisocyanate, polyphenyl polymethylene polyisocyanate, amino-modified isocyanate, and carbodiimide-modified isocyanate.

[0023] Preferably, the catalyst is one or more of a polyurethane heat-sensitive catalyst, a polyurethane delayed catalyst and a polyurethane polymerization inhibitor.

[0024] Preferably, the C component expandable foam microspheres are particles with a polymer obtained by polymerizing acrylonitrile or acrylate as a monomer as the core-shell layer and a low-boiling-point alkane as the core layer.

[0025] Further preferably, the low boiling point alkane is a C4-C12 alkane; and the particle size of the expanded foam microsphere is 10-30 μm.

[0026] According to another aspect of the present invention, there is provided a method for preparing the rigid polyurethane electronic foam, comprising the following steps:

[0027] The polyol mixture of component A, isocyanate of component B and expandable foaming microspheres of component C are stirred and mixed, coated on a releasable support, and heated and cured at a temperature of 90° C. to 200° C. to obtain the polyurethane electronic foam.

[0028] In general, the above technical solution conceived by the present invention has the following beneficial effects compared with the prior art:

[0029] (1) The present invention provides a rigid polyurethane electronic foam with a high open porosity, wherein expandable foaming microspheres are introduced during the foaming process, and the curing temperature during the preparation of the foam is controlled to be greater than the maximum expansion temperature of the expandable foaming microspheres. When the heating curing temperature exceeds the maximum temperature at which the microspheres have the maximum expansion volume, the microspheres will rupture, thereby forming more open pores on the surface and inside of the foam.

[0030] (2) In the preferred embodiment of the present invention, the polyurethane foaming catalytic system uses a polyurethane thermosensitive catalyst, a polyurethane delayed catalyst and a polyurethane polymerization inhibitor, which can be used alone or in combination to ensure that the foam has sufficient gel time so that the expanded foam microspheres can fully expand and explode. At the same time, the expanded foam microspheres are preferably low-temperature expanded foam microspheres. The low-temperature expanded foam microspheres have a lower initial expansion temperature and a lower maximum expansion temperature. Low-temperature foaming helps to extend the gel time of the foam and facilitates the expanded foam microspheres to fully explode before the foam is completely gelled.

[0031] (3) In the preferred embodiment of the present invention, tetrafunctional or higher polyether polyols are selected as the main polyether in the foam, and the content is relatively high. The polymer foam has a high degree of crosslinking, which ensures the hardness. The high degree of crosslinking also ensures uniform and fine pores in the foam.

[0032] (4) The expanded foam microspheres have different particle sizes. When the particles with smaller particle sizes explode, the openings formed are smaller in diameter. On the contrary, the openings formed are larger in diameter. In the preferred embodiment of the present invention, the type of catalyst and the amount of catalyst used are selected, the gel time is controlled, and the appropriate type of low-temperature foam microspheres are selected, so as to control the opening porosity and pore size of the foam.

[0033] (5) In addition to having a certain hardness, polyurethane rigid foam is also required to have a certain toughness. The present invention introduces polyether diol into the foam to ensure its toughness. The polyether diol forms a linear structure in the foam structure, which improves the elongation and avoids the brittleness of the foam caused by excessive cross-linking. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0035] Microporous polyurethane rigid foam has high density and hardness, and is prone to closed cells during the actual production process, which leads to foam shrinkage and reduces the production qualification rate of foam. To solve the shrinkage problem, the traditional approach is to add a certain amount of modified silicone or polyether pore openers to increase the open porosity of the foam. Adding modified silicone or polyether pore openers sometimes cannot completely solve the shrinkage of the foam, and too much addition will have an adverse effect on the performance of the foam. To this end, the present invention provides a rigid polyurethane electronic foam with a high open porosity, the raw materials of which include a polyol mixture of component A, isocyanate of component B, and expandable foaming microspheres of component C; wherein,

[0036] The C component is expandable foam microspheres, and its maximum expansion temperature is ≤160°C;

[0037] The polyurethane foam is obtained after the polyol of component A, the isocyanate of component B and the expandable foaming microspheres of component C are mixed and cured to form; and the curing temperature is greater than the maximum expansion temperature of the foaming microspheres.

[0038] The present invention is also equivalent to providing a method for increasing the porosity of rigid polyurethane electronic foam. Expandable foaming microspheres are introduced into the foam raw materials. Under high temperature conditions, the liquid alkane inside the microspheres expands rapidly. When the external heating temperature exceeds the maximum temperature of the microspheres at the maximum expansion volume, the spheres will rupture, thereby forming more pores on the surface and inside of the foam, thereby increasing the porosity of the foam.

[0039] The expandable foaming microspheres of the present invention, also referred to as expandable microspheres or foaming microspheres, are a type of thermoplastic hollow polymer microspheres, which are composed of a thermoplastic polymer shell and a sealed liquid alkane gas. When heated, the gas pressure in the shell increases and the thermoplastic shell softens, thereby significantly increasing the volume of the expandable microspheres. The maximum expansion temperature of the expandable foaming microspheres is defined as the heating temperature corresponding to when the microspheres reach the maximum expansion volume. When the polyurethane electronic foam of the present invention is prepared, the A component polyol, the B component isocyanate and the C component expandable foaming microspheres are mixed and then heated for curing, and the curing temperature is defined to be higher than the maximum expansion temperature of the expandable foaming microspheres, so as to achieve a high open porosity of the foam.

[0040] In some embodiments, the mass ratio of the polyol of component A, the isocyanate of component B and the expandable foaming microsphere of component C is 100:(40-70):(1-10), preferably 100:(40-70):(3-5).

[0041] In some embodiments, the polyol mixture of component A includes 50-80 parts by weight of high-functionality polyether polyol, 20-50 parts by weight of difunctionality polyether polyol, 0.5-2.5 parts by weight of surfactant, 0.5-3 parts by weight of pore opener, 0.1-1.0 parts by weight of catalyst, 0-3 parts by weight of small molecule active hydrogen compound, and 1-5 parts by weight of color paste; and / or,

[0042] The B component isocyanate includes diphenylmethane diisocyanate or a modified derivative thereof, polyphenyl polymethylene polyisocyanate or a modified derivative thereof.

[0043] In some embodiments, the high-functionality polyether polyol is a polyether polyol with a small molecule of tetrafunctionality or above as an initiator; the difunctionality polyether polyol is a polyether diol with a small molecule of difunctionality as an initiator.

[0044] In some embodiments, the surfactant is polyether-modified polydimethylsiloxane; and the pore opener is ORTEGOL 501.

[0045] In some embodiments, the catalyst is one or more of a polyurethane thermosensitive catalyst, a polyurethane delayed catalyst and a polyurethane polymerization inhibitor, and such catalysts commonly used in the prior art or commercially available can be selected.

[0046] In a preferred embodiment, the polyurethane delayed catalyst is a polyurethane amine delayed catalyst or a polyurethane heat-sensitive delayed metal catalyst, which is one or more of dioctyltin dimercaptoacetate (UL-29), CUCAT-RM30, CUCAT-RM30D, CUCAT-RM301, C225, MP601, MP602, MP608, etc. The polyurethane heat-sensitive catalyst is one or more of ECOADD8815, ECOADD8817, ECOADD8819, TOYOCAT DB30, TOYOCAT DB60, etc. The polyurethane polymerization inhibitor is one or more of NCAT-YC01, NCAT-YC02, NCAT-YC03, etc.

[0047] The raw materials of the rigid polyurethane electronic foam of the present invention are introduced with expanding foaming microspheres, and the curing heating temperature during curing is set to be higher than the maximum expansion temperature of the expanding foaming microspheres. In a preferred embodiment, in order to promote the full foaming of the expanding foaming microspheres, a catalyst capable of delaying the foam gel time is introduced into the foam. The catalyst includes but is not limited to one or more of a polyurethane thermosensitive catalyst, a polyurethane delayed catalyst and a polyurethane polymerization inhibitor. The polyurethane thermosensitive catalyst has a very low reaction activity at room temperature, and its catalytic activity gradually increases with the increase of temperature, or it loses its activity within a certain range after being sealed with a sealing agent. When the temperature is increased to a certain degree, the sealing is released and the catalytic activity is restored, so that the foam gel time may be enhanced to ensure that the expanding microspheres are fully expanded and open. The polyurethane delayed catalyst uses a larger sterically hindered alkyl group to replace a smaller sterically hindered group, and the steric hindrance decreases with the increase of temperature, thereby extending the foam gel time to ensure that the expanding microspheres are fully expanded and open. The polyurethane polymerization inhibitor has a slowing effect on the NCO nucleophilic addition reaction, slows down the chain growth, and can extend the polymerization time, thereby extending the foam gel time to ensure that the expanding microspheres are fully expanded and open.

[0048] In some embodiments, the small molecule active hydrogen compound in the polyol mixture of component A is one or more of ethylenediamine, butanediol, ethylene glycol, propylene glycol, glycerol, trimethylolpropane, trimethylolethane, diisopropanolamine, triisopropanolamine, diethanolamine, and triethanolamine.

[0049] In some embodiments, the B component isocyanate is one or more of 4,4'-diphenylmethane diisocyanate (MDI100), a mixture of 2,4'-diphenylmethane diisocyanate and 4,4'-diphenylmethane diisocyanate (liquefied MDI-50), carbodiimide-modified 4,4'-diphenylmethane diisocyanate (liquefied MDI), and polymethylene polyphenyl polyisocyanate (PAPI).

[0050] In some embodiments, the C component expandable foam microspheres are particles having a polymer obtained by polymerizing acrylonitrile (AN) or acrylate as a monomer as a core-shell layer and a low-boiling-point alkane as a core layer.

[0051] In some embodiments, the core-shell layer is an acrylic acid polymer or an acrylonitrile polymer, the low-boiling point alkane is a C4-C12 alkane, and the particle size of the expanded foam microsphere is 10-30 μm.

[0052] In a preferred embodiment, the maximum expansion temperature of the expandable foamed microspheres is less than or equal to 150°C.

[0053] The present invention also provides a method for preparing the rigid polyurethane electronic foam, which in some embodiments comprises the following steps: the high-functionality polyether polyol, difunctionality polyether polyol, surfactant, pore-opening agent, catalyst, small molecule active hydrogen compound, and color paste are stirred and mixed uniformly to obtain a polyol mixture of component A. The polyol mixture of component A, isocyanate of component B, and expandable foaming microspheres of component C are stirred and mixed, and then coated on a releasable support, and heated and cured at a temperature of 90°C to 200°C to obtain the polyurethane foam.

[0054] In some embodiments, the stirring and mixing is performed at a speed of 1500-2500 r / min, the stirring time is 10-60 s, and the heating and curing time is 5-20 min. The releasable support is a release paper or a releasable PET.

[0055] The following are examples:

[0056] Example 1

[0057] 80 parts by mass of polypropylene oxide polyether tetraol (molecular weight 1000, GP-410), 20 parts by mass of polypropylene oxide diol (molecular weight 1000, PPG-1000), 0.3 parts by mass of polyurethane delayed organic tin catalyst UL-29, 0.2 parts by mass of polyurethane inhibitor NCAT-YC01, 0.5 parts by mass of polyether modified polydimethylsiloxane surfactant (commercially available B8525 from Evonik), 0.5 parts by mass of pore opener (ORTEGOL 501), 2 parts by mass of ethylene glycol, and 1 part by mass of color paste (black color paste, Milliken BLACKX95AB) were stirred and mixed to obtain a component A polyol mixture.

[0058] The isocyanate in component B is MDI50.

[0059] Component C is foamed microspheres with a particle size of 20-30 μm and a maximum expansion temperature of 125° C. (model MS140D, a product sold by Beijing Hujin Technology Co., Ltd.).

[0060] The polyol mixture of component A, the isocyanate of component B, and the foaming microspheres of component C were stirred for 30 seconds at a mass ratio of 100:43.3:3 (speed of 2000 r / min), applied on the surface of the release paper, and heated and cured at 135° C. for 10 minutes to obtain the desired polyurethane foam.

[0061] Example 2

[0062] 60 parts by mass of polypropylene oxide polyether tetraol (molecular weight 700, GP-407), 40 parts by mass of polypropylene oxide diol (molecular weight 1500, PPG-1500), 0.3 parts by mass of polyurethane delayed release catalyst C225, 0.5 parts by mass of polyether modified polydimethylsiloxane surfactant (commercially available B8525 from Evonik), 0.5 parts by mass of polyoxyalkylene polysiloxane copolymer pore opener (ORTEGOL 501), 2 parts by mass of 1,4-butanediol, and 1 part by mass of color paste (black color paste, Milliken BLACK X95AB) were stirred and mixed to obtain a component A polyol mixture.

[0063] The isocyanate of component B is carbodiimide-modified MDI (model WANNATE CDMDI-100L).

[0064] Component C is foamed microspheres with a particle size of 15-25 μm and a maximum expansion temperature of 145°C (model MS145D).

[0065] The polyol mixture of component A, the isocyanate of component B, and the foaming microspheres of component C were stirred for 30 seconds at a mass ratio of 100:51.4:3 (speed of 2000 r / min), applied on the surface of the release paper, and heated and cured at 150° C. for 10 minutes to obtain the desired polyurethane foam.

[0066] Example 3

[0067] 50 parts by mass of polypropylene oxide polyether tetraol (molecular weight 550, GP-405), 50 parts by mass of polypropylene oxide diol (molecular weight 2000, PPG-2000), 0.3 parts by mass of polyurethane delayed catalyst MP601, 0.2 parts by mass of polyurethane thermosensitive catalyst ECOADD8815, 0.2 parts by mass of polyurethane inhibitor NCAT-YC03, 0.5 parts by mass of polyether modified polydimethylsiloxane surfactant (commercially available B8525 from Evonik), 0.5 parts by mass of polyoxyalkylene polysiloxane copolymer pore opener (ORTEGOL501), 2 parts by mass of propylene glycol, and 1 part by mass of color paste (black color paste, Milliken BLACK X95AB) were stirred and mixed to obtain a component A polyol mixture.

[0068] The isocyanate in component B is PAPI.

[0069] Component C is foamed microspheres with a particle size of 10-20 μm and a maximum expansion temperature of 135°C (model 120DU15).

[0070] The polyol mixture of component A, the isocyanate of component B, and the foaming microspheres of component C were stirred and mixed at a mass ratio of 100:53:3 (speed of 2000r / min), applied on the surface of the release paper, and heated and cured at 135°C for 10 minutes to obtain the desired polyurethane foam.

[0071] Example 4

[0072] 60 parts by mass of polypropylene oxide polyether pentaol (molecular weight 1000, GP-510), 40 parts by mass of polypropylene oxide diol (molecular weight 1000, PPG-1000), 0.2 parts by mass of polyurethane delayed catalyst MP602, 0.3 parts by mass of polyurethane inhibitor NCAT-YC03, 0.5 parts by mass of polyether modified polydimethylsiloxane surfactant (B8525 commercially available from Evonik), 1.0 parts by mass of polyoxyalkylene polysiloxane copolymer pore opener (ORTEGOL 501), 2 parts by mass of ethylene glycol, and 1 part by mass of color paste (black color paste, Milliken BLACK X95AB) were stirred and mixed to obtain a component A polyol mixture.

[0073] The isocyanate in component B is MDI50.

[0074] Component C is foamed microspheres (model MS140D) with a particle size of 20-30 μm and a maximum expansion temperature of 125°C.

[0075] The polyol mixture of component A, the isocyanate of component B, and the foaming microspheres of component C were stirred and mixed at a mass ratio of 100:50.5:4 (speed of 2000r / min), applied on the surface of release paper, and heated and cured at 135°C for 10 minutes to obtain the desired polyurethane foam.

[0076] Example 5

[0077] 55 parts by mass of polypropylene oxide polyether pentaol (molecular weight 800, GP-508), 45 parts by mass of polypropylene oxide diol (molecular weight 1500, PPG-1500), 0.3 parts by mass of polyurethane delayed catalyst MP608, 0.2 parts by mass of polyurethane thermosensitive catalyst TOYOCAT DB30, 0.2 parts by mass of polyurethane inhibitor NCAT-YC03, 0.5 parts by mass of polyether modified polydimethylsiloxane surfactant (commercially available B8525 from Evonik), 1.0 parts by mass of polyoxyalkylene polysiloxane copolymer pore opener (ORTEGOL501), 1 parts by mass of 1,4-butanediol, and 1 parts by mass of color paste (black color paste, Milliken BLACK X95AB) were stirred and mixed to obtain a component A polyol mixture.

[0078] The isocyanate of component B is liquefied 100 (carbodiimide modified MDI, model WANNATE CDMDI-100L).

[0079] Component C is foamed microspheres with a particle size of 15-25 μm and a maximum expansion temperature of 145°C (model MS145D).

[0080] The polyol mixture of component A, the isocyanate of component B, and the foaming microspheres of component C were stirred and mixed at a mass ratio of 100:55:4 (speed of 2000r / min), applied on the surface of release paper, and heated and cured at 150°C for 10 minutes to obtain the desired polyurethane foam.

[0081] Example 6

[0082] 50 parts by mass of polypropylene oxide polyether pentaol (molecular weight 600, GP-506), 50 parts by mass of polypropylene oxide diol (molecular weight 2000, PPG-2000), 0.1 parts by mass of polyurethane delayed catalyst MP608, 0.2 parts by mass of polyurethane inhibitor NCAT-YC01, 0.5 parts by mass of polyether modified polydimethylsiloxane surfactant (B8525 commercially available from Evonik), 1.0 parts by mass of polyoxyalkylene polysiloxane copolymer pore opener (ORTEGOL 501), 1 part by mass of propylene glycol, and 1 part by mass of color paste (black color paste, Milliken BLACK X95AB) were stirred and mixed to obtain a component A polyol mixture.

[0083] The isocyanate in component B is PAPI.

[0084] Component C is foamed microspheres with a particle size of 20-30 μm and a maximum expansion temperature of 130°C (model 120DU25).

[0085] The polyol mixture of component A, the isocyanate of component B, and the foaming microspheres of component C were stirred and mixed at a mass ratio of 100:53:4 (speed of 2000r / min), applied on the surface of the release paper, and heated and cured at 180°C for 10 minutes to obtain the desired polyurethane foam.

[0086] Example 7

[0087] 60 parts by mass of polypropylene oxide polyether hexaol (molecular weight 1000, GP-610), 40 parts by mass of polypropylene oxide diol (molecular weight 1500, PPG-1500), 0.1 parts by mass of polyurethane delayed catalyst MP608, 0.2 parts by mass of polyurethane inhibitor NCAT-YC02, 0.5 parts by mass of polyether modified polydimethylsiloxane surfactant (commercially available B8525 from Evonik), 1.5 parts by mass of polyoxyalkylene polysiloxane copolymer pore opener (or501), and 1 part by mass of color paste (black color paste, Milliken BLACKX95AB) were stirred and mixed to obtain a component A polyol mixture.

[0088] The isocyanate in component B is MDI50.

[0089] Component C is foamed microspheres with a particle size of 20-30 μm and a maximum expansion temperature of 130°C (model 120DU25).

[0090] The polyol mixture of component A, the isocyanate of component B, and the foaming microspheres of component C were stirred and mixed at a mass ratio of 100:52:5 (speed of 2000r / min), applied on the surface of the release paper, and heated and cured at 135°C for 10 minutes to obtain the desired polyurethane foam.

[0091] Example 8

[0092] 55 parts by mass of polypropylene oxide polyether hexaol (molecular weight 800, GP-608), 45 parts by mass of polypropylene oxide diol (molecular weight 2000, PPG-2000), 0.1 parts by mass of polyurethane thermal catalyst TOYOCAT DB30, 0.2 parts by mass of polyurethane inhibitor NCAT-YC01, 0.5 parts by mass of polyether modified polydimethylsiloxane surfactant (commercially available B8525 from Evonik), 1.5 parts by mass of polyoxyalkylene polysiloxane copolymer pore opener (ORTEGOL 501), and 1 part by mass of color paste (black color paste, Milliken BLACK X95AB) were stirred and mixed to obtain a component A polyol mixture.

[0093] The isocyanate of component B is liquefied 100 (carbodiimide modified MDI, model WANNATE CDMDI-100L).

[0094] Component C is foamed microspheres with a particle size of 15-25 μm and a maximum expansion temperature of 145°C (model MS145D).

[0095] The polyol mixture of component A, the isocyanate of component B, and the foaming microspheres of component C were stirred and mixed at a mass ratio of 100:64:5 (speed of 2000r / min), applied on the surface of the release paper, and heated and cured at 150°C for 10 minutes to obtain the desired polyurethane foam.

[0096] Example 9

[0097] 50 parts by mass of polypropylene oxide polyether hexaol (molecular weight 700, GP-607), 50 parts by mass of polypropylene oxide diol (molecular weight 2500, PPG-2500), 0.05 parts by mass of polyurethane delayed catalyst MP608, 0.05 parts by mass of polyurethane thermal catalyst TOYOCAT DB30, 0.3 parts by mass of polyurethane inhibitor NCAT-YC03, 0.5 parts by mass of polyether modified polydimethylsiloxane surfactant (commercially available B8525 from Evonik), 1.5 parts by mass of polyoxyalkylene polysiloxane copolymer pore opener (ORTEGOL 501), and 1 part by mass of color paste (black color paste, Milliken BLACK X95AB) were stirred and mixed to obtain a component A polyol mixture.

[0098] The isocyanate in component B is PAPI.

[0099] Component C is foamed microspheres (model MS140D) with a particle size of 20-30 μm and a maximum expansion temperature of 125°C.

[0100] The polyol mixture of component A, the isocyanate of component B, and the foaming microspheres of component C were stirred and mixed at a mass ratio of 100:60:5 (speed of 2000r / min), applied on the surface of release paper, and heated and cured at 180°C for 10 minutes to obtain the desired polyurethane foam.

[0101] Comparative Example 1

[0102] In this comparative example, polypropylene oxide tetraol was replaced with polypropylene oxide triol (molecular weight 700, GP307), and the rest was the same as in Example 1.

[0103] Comparative Example 2

[0104] In this comparative example, all the polypropylene oxide diols were replaced with the polypropylene oxide tetraol of Example 1, and the rest were the same as Example 1.

[0105] Comparative Example 3

[0106] In this comparative example, the expandable foamed microspheres used have a maximum expansion temperature of 175-185°C, a particle size of 30-40 μm, a model of 180DU45, a coating temperature of 195°C, and the rest are the same as in Example 1.

[0107] Comparative Example 4

[0108] In this comparative example, the coating temperature is 90°C, and the rest is the same as in Example 1.

[0109] Comparative Example 5

[0110] In this comparative example, ordinary gel-type amine catalyst A33 was used, and the rest was the same as in Example 1.

[0111] Comparative Example 6

[0112] In this comparative example, a metal catalyst (bismuth isooctanoate) was used, and the rest was the same as in Example 1.

[0113] The foams prepared in the embodiments and comparative examples were tested by the following method:

[0114] 1. Cut the coated samples of the same thickness into discs with a diameter of 2.5 cm, and count the number of openings on the foam surface at the same focal length (the number of openings on the foam surface represents the porosity) and the size of the pores;

[0115] 2. Cut the coated samples of the same thickness into discs with a diameter of 2.5 cm, fold them 180°, and observe the cracking and fracture within 5 minutes (whether there is cracking and the cracking time) to judge the toughness of the foam;

[0116] 3. Cut the coated samples of the same thickness into discs with a diameter of 2.5 cm, and use a Shore 00 hardness tester to test the hardness of the foams of different embodiments and comparative examples at the same thickness;

[0117] 4. The coated samples of the same thickness were cut into discs with a diameter of 2.5 cm, and the density of the foams of different embodiments and comparative examples was tested using the mass volume method.

[0118] The results of Example 1 and Comparative Examples 1 to 5 are shown in Table 1 below:

[0119] Table 1

[0120]

[0121]

[0122] Compared with Example 1, in Comparative Example 1, polypropylene oxide tetraol is replaced with polypropylene oxide triol, and the pore diameter becomes larger and the pore uniformity becomes worse; in Comparative Example 2, polypropylene oxide diol is removed from the foaming system, and the foam is measured to be broken, indicating that polypropylene oxide diol is beneficial to improving the toughness of the foam; Comparative Example 3 uses high-temperature expandable microspheres with a maximum expansion temperature of 175-185°C and a particle size of 30-40 μm. The maximum expansion temperature is high, the particle size is large, the foam solidifies too quickly, and there is no time to open the holes, resulting in a low open porosity and poor appearance; in Comparative Example 4, the coating temperature, i.e., the curing temperature, is lower than the maximum expansion temperature of the expandable microspheres, resulting in a low open porosity and severe shrinkage of the bubbles; Comparative Examples 5 and 6 respectively use ordinary gel-type amine catalysts and metal catalysts, which may cause the foam gel time to be insufficiently long, resulting in a low open porosity and severe shrinkage of the obtained foam.

[0123] The results of Examples 2 to 8 are shown in Table 2 below:

[0124] Table 2

[0125]

[0126] In summary, the microporous polyurethane rigid foam prepared by the present invention has good appearance and no shrinkage, the open porosity of the foam surface is increased by about one time, the product molding qualification rate is high, and the market requirements are met.

[0127] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A rigid polyurethane electronic foam with a high open porosity, characterized in that: The raw materials include component A polyol mixture, component B isocyanate and component C expandable foam microspheres; wherein, The maximum expansion temperature of the expandable foamed microspheres of component C is ≤160°C; The polyurethane electronic foam is obtained after the polyol of component A, the isocyanate of component B and the expandable foaming microspheres of component C are mixed and cured to form; and the curing temperature is greater than the maximum expansion temperature of the expandable foaming microspheres.

2. The rigid polyurethane electronic foam according to claim 1, characterized in that: The mass ratio of the polyol of component A, the isocyanate of component B and the expanded foaming microsphere of component C is 100:(40-70):(1-10).

3. The rigid polyurethane electronic foam according to claim 1, characterized in that: The polyol mixture of component A comprises 50-80 parts by weight of high-functionality polyether polyol, 20-50 parts by weight of difunctionality polyether polyol, 0.5-2.5 parts by weight of surfactant, 0.5-3 parts by weight of pore opener, 0.1-1.0 parts by weight of catalyst, 0-3 parts by weight of small molecule active hydrogen compound, and 1-5 parts by weight of color paste; and / or, The B component isocyanate includes one or more of diphenylmethane diisocyanate, polyphenyl polymethylene polyisocyanate, amino-modified isocyanate, and carbodiimide-modified isocyanate.

4. The rigid polyurethane electronic foam as claimed in claim 3, characterized in that: The high-functionality polyether polyol is a polyether polyol using a small molecule with tetrafunctionality or above as an initiator; the difunctionality polyether polyol is a polyether diol using a small molecule with difunctionality as an initiator.

5. The rigid polyurethane electronic foam as claimed in claim 3, characterized in that: The surfactant is polyether-modified polydimethylsiloxane.

6. The rigid polyurethane electronic foam as claimed in claim 3, characterized in that: The catalyst is one or more of a polyurethane heat-sensitive catalyst, a polyurethane delayed catalyst and a polyurethane polymerization inhibitor.

7. The rigid polyurethane electronic foam as claimed in claim 3, characterized in that: The small molecular active hydrogen compound in the A component polyol mixture is one or more of ethylenediamine, butanediol, ethylene glycol, propylene glycol, glycerol, trimethylolpropane, trimethylolethane, diisopropanolamine, triisopropanolamine, diethanolamine and triethanolamine.

8. The rigid polyurethane electronic foam as claimed in claim 3, characterized in that: The B component isocyanate is one or more of 4,4'-diphenylmethane diisocyanate, a mixture of 2,4'-diphenylmethane diisocyanate and 4,4'-diphenylmethane diisocyanate, carbodiimide-modified 4,4'-diphenylmethane diisocyanate, and polymethylene polyphenyl polyisocyanate.

9. The rigid polyurethane electronic foam according to claim 1, characterized in that: The C component expandable foam microspheres are particles with a polymer polymerized with acrylonitrile or acrylate as monomers as core-shell layers and low-boiling-point alkanes as core layers; Preferably, the low boiling point alkane is a C4-C12 alkane; and the particle size of the expanded foam microsphere is 10-30 μm.

10. The method for preparing the rigid polyurethane electronic foam according to any one of claims 1 to 9, characterized in that: The steps include: The polyol mixture of component A, isocyanate of component B and expandable foaming microspheres of component C are stirred and mixed, coated on a releasable support, and heated and cured at a temperature of 90° C. to 200° C. to obtain the polyurethane electronic foam.

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