Micro-foaming self-repairing material, preparation method thereof, bottom shell and air conditioner

Abstract

The invention provides a micro-foaming self-repairing material and a preparation method thereof, a bottom shell and an air conditioner, and relates to the technical field of air conditioners. Wherein both the surface layer and the core layer are provided with micropores; the surface layer and the core layer are polymer matrixes; the polymer matrix comprises ABS resin and polyurethane resin; when the micro-foaming self-repairing material is used for preparing the bottom shell of the air conditioner, when the bottom shell is cracked, the bottom shell does not need to be replaced or repaired by using an adhesive, the operation is simple, other parts can be prevented from being damaged by disassembling, and the cost is reduced; the strength and impact resistance of the bottom shell can be effectively enhanced, stress distribution is improved, and the cracking risk is greatly reduced; when the surface of the bottom shell cracks, external water vapor enters cracks, the micro-foaming self-repairing material absorbs water and expands, the cracks are filled with the micro-foaming self-repairing material, the tips of the cracks are filled with the micro-foaming self-repairing material, the polyurethane resin can become a hard plastic shape after the micro-foaming self-repairing material is dried, and therefore the cracks of the bottom shell are repaired.

Description

Technical Field

[0001] The present invention belongs to the technical field of air conditioners, and in particular relates to a micro-foamed self-repairing material and a preparation method thereof, a bottom shell and an air conditioner. Background Art

[0002] As an indispensable electrical device in our lives, air conditioners have the important task of providing us with a cool and comfortable environment. As a consumable product in daily life, the service life of air conditioners is mostly 5-10 years. However, various problems will inevitably arise in air conditioners under long-term use, affecting the performance and use of air conditioners. Among them, the bottom shell is now mostly made of polymer materials such as ABS resin injection molding. The performance of these polymer materials will age with the increase of years of use, causing stress cracking or deformation of the bottom shell, which in turn leads to water leakage in the bottom shell.

[0003] At present, the common treatment methods in the air-conditioning field for the problem of bottom shell leakage are to replace the bottom shell or repair it with adhesive, but both involve disassembling the entire machine, and the disassembly process is prone to cause secondary damage to other parts (such as the panel body), which is not only complicated to operate, but also costly. Summary of the invention

[0004] Therefore, the present invention provides a micro-foamed self-repairing material and a preparation method thereof, a bottom shell and an air conditioner, which can solve the problem of bottom shell cracking in the prior art.

[0005] In order to solve the above problems, the present invention provides a micro-foamed self-healing material, which includes a surface layer and a core layer; wherein the surface layer and the core layer both have micropores; the surface layer and the core layer are both polymer matrices; the polymer matrix includes ABS resin and polyurethane resin.

[0006] Furthermore, the density of the micropores in the core layer is 1.0×10 6 -1.0×10 15 Pieces / cm 3 ; and / or

[0007] The average pore size of the micropores in the core layer is 10-100 μm; and / or

[0008] The volume expansion ratio of the micro-foamed self-repairing material is 2-60 times.

[0009] Furthermore, the density of micropores in the surface layer is 1.0×10 9 -1.0×10 12 Pieces / cm 3 ; and / or

[0010] The average pore size of the micropores in the surface layer is 0.1-10 μm; and / or

[0011] The thickness of the surface layer is 3-5 mm.

[0012] On the other hand, the present invention provides a method for preparing any one of the micro-foam self-repairing materials, wherein the raw materials for preparing the micro-foam self-repairing material include, by weight:

[0013] 70-80 parts of ABS resin, 15-20 parts of polyurethane resin, 0.5-5 parts of compatibilizer, 1-2 parts of nucleating agent, 0.1-5 parts of antioxidant.

[0014] Furthermore, the relative molecular weight of the ABS resin is 80,000-200,000.

[0015] Furthermore, the polyurethane resin is a moisture curable polyurethane resin; and / or

[0016] The molar ratio of isocyanate groups to polyols in the polyurethane resin is 1.2-1.5:1.

[0017] Furthermore, the compatibilizer is one or more of a surfactant, a silane coupling agent, a maleic anhydride modified polymer, and an acrylate.

[0018] Further, the surfactant comprises polysiloxane and / or polyether siloxane copolymer; and / or

[0019] The silane coupling agent includes γ-(methacryloyloxy)propyltrimethoxysilane and / or γ-aminopropyltriethoxysilane; and / or

[0020] The maleic anhydride modified polymer includes one or more of maleic anhydride grafted polyethylene, maleic anhydride grafted polypropylene, and maleic anhydride grafted polystyrene.

[0021] Furthermore, the nucleating agent is an organic nucleating agent and / or an inorganic nucleating agent;

[0022] Wherein, the organic nucleating agent includes one or more of surfactant, 3-trimethoxysilylpropyl methacrylate, polyamide wax, and polyethylene wax;

[0023] The inorganic nucleating agent includes one or more of metal soap, talc, silicon dioxide, and calcium carbonate.

[0024] Further, the surfactant comprises polysiloxane and / or polyether siloxane copolymer; and / or

[0025] The metal soap includes zinc stearate and / or calcium stearate.

[0026] Furthermore, the antioxidant is one or more of a phenolic antioxidant, a phosphite antioxidant, and a thioester antioxidant.

[0027] Further, the phenolic antioxidant includes 2,6-di-tert-butyl-4-methylphenol and / or tetraethyl bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate]; and / or

[0028] The phosphite antioxidant includes N,N'-1,6-hexylene-bis-[3,5-di-tert-butyl-4-hydroxyphenylpropionamide] and / or tris(2,4-di-tert-butyl)phenyl phosphite; and / or

[0029] The thioester antioxidant includes bis(2,6-di-tert-butyl-4-methylphenyl)sulfurized phosphite.

[0030] Furthermore, the preparation method comprises the following steps:

[0031] The raw material is formed into the micro-foamed self-repairing material by using a supercritical fluid as a foaming agent.

[0032] Furthermore, the step of molding the raw material into the micro-foamed self-repairing material includes:

[0033] Step 1) mixing the raw materials and then melting them to obtain a polymer melt;

[0034] Step 2) injecting a supercritical fluid into the polymer melt under a set pressure for mixing, so that the supercritical fluid is dissolved in the polymer melt; then reducing the pressure to allow the supercritical fluid to precipitate from the polymer melt to form bubbles, and obtain a foaming material;

[0035] Step 3) The foaming material is cooled, solidified, and moisture-cured to obtain the micro-foamed self-repairing material.

[0036] Furthermore, in the step 1):

[0037] The ABS resin, polyurethane resin, compatibilizer, nucleating agent and antioxidant are mixed and added into an extruder, and the raw materials are heated and melted by the screw of the extruder to obtain a polymer melt; or

[0038] The ABS resin, polyurethane resin, compatibilizer, nucleating agent and antioxidant are mixed and added to an extruder, the raw materials are heated and melted by the screw of the extruder, and then granulated to obtain master batches; the master batches are added to an extruder, the master batches are heated and melted by the screw of the extruder to obtain a polymer melt.

[0039] Furthermore, the heating temperature of the screw of the extruder is 220°C-240°C.

[0040] Further, under a set pressure, the supercritical fluid is injected into the polymer melt by a high-pressure pump, and the supercritical fluid swells and diffuses into the polymer melt for 1-5 minutes, so that the supercritical fluid is dissolved in the polymer melt; and / or

[0041] The supercritical fluid is separated from the polymer melt by reducing the pressure through a pressure release valve.

[0042] Furthermore, the supercritical fluid is carbon dioxide or nitrogen; and / or

[0043] The decompression rate of the decompression treatment is 1-1000 MPa / s; and / or

[0044] The set pressure is 10-15 MPa; and / or

[0045] The cooling speed is 25-45°C / min.

[0046] In another aspect, the present invention provides a bottom shell of an air conditioner, wherein the bottom shell is made of any of the above-mentioned micro-foamed self-repairing materials.

[0047] In another aspect, the present invention provides a method for preparing the above-mentioned air conditioner bottom case, comprising the following steps:

[0048] Step 1) mixing the raw materials and then melting them to obtain a polymer melt; wherein the raw materials include ABS resin, polyurethane resin, compatibilizer, nucleating agent, and antioxidant;

[0049] Step 2) Under a set pressure, a supercritical fluid is injected into the polymer melt for mixing to obtain a homogeneous solution; the homogeneous solution is injected into a mold of a bottom shell, and then decompressed to allow the supercritical fluid to precipitate from the homogeneous solution to form bubbles, thereby obtaining a foaming material;

[0050] Step 3) After the foaming material is cooled, solidified, and moisture-cured, the bottom shell is obtained.

[0051] In another aspect, the present invention provides an air conditioner, comprising the bottom casing described above.

[0052] Compared with the prior art, the present invention has at least the following beneficial effects:

[0053] 1. On the one hand, the present invention provides a micro-foamed self-repairing material, which includes a surface layer and a core layer; wherein the surface layer and the core layer both have micropores; the surface layer and the core layer are both polymer matrices; the polymer matrix includes ABS resin and polyurethane resin; the above-mentioned micro-foamed self-repairing material is used to prepare the bottom shell of the air conditioner. When the bottom shell is cracked, there is no need to replace the bottom shell or use adhesive to repair it. The operation is simple, and it can avoid disassembling and damaging other parts, thereby reducing costs; it should be noted that the micro-foamed self-repairing material can effectively enhance the strength and impact resistance of the bottom shell, improve stress distribution, and greatly reduce the risk of cracking; when the surface of the bottom shell (substrate) is cracked, external water vapor enters the crack, and the micro-foamed self-repairing material absorbs water and expands, filling the inside of the crack to fill the crack, and filling the crack tip. After drying, the polyurethane resin will become a hard plastic, thereby repairing the crack of the bottom shell, thereby avoiding water leakage caused by cracking.

[0054] 2. Another invention, the present invention provides a preparation method of the above-mentioned micro-foamed self-repairing material, the raw materials of which include: 70-80 parts of ABS resin, 15-20 parts of polyurethane resin, 0.5-5 parts of compatibilizer, 1-2 parts of nucleating agent, and 0.1-5 parts of antioxidant; wherein, ABS resin is the main material of the bottom shell of the air conditioner or the air conditioner drain pan to ensure the mechanical properties of the bottom shell, etc.; polyurethane resin can effectively enhance the strength and impact resistance of the bottom shell, etc., improve stress distribution, and greatly reduce the risk of cracking; compatibilizer can act as a compatible bridge, thereby improving the compatibility of ABS resin and polyurethane resin; nucleating agent can promote the nucleation and stabilization of bubbles in the polymer matrix, thereby affecting the pore structure of the final foaming material, therefore, reasonable selection and use of nucleating agent can significantly improve the pore uniformity and quantity of micro-foamed self-repairing material; antioxidant, to make up for the shortcoming of poor antioxidant property of polyurethane resin, can improve the anti-aging property of the bottom shell and extend its service life;

[0055] Among them, the polyurethane resin is set to 15-20 parts to avoid the inability to achieve self-repair function or the deterioration of the repair effect when the amount of polyurethane is low; when the amount of polyurethane resin is high, although the impact resistance (i.e. toughness) of the material will be improved to a certain extent, the overall mechanical strength, thermal properties and chemical resistance will be attenuated to a certain extent, and the processing difficulty of the material will be increased to a certain extent.

[0056] 3. Furthermore, the preparation method of the above-mentioned micro-foamed self-healing material uses a supercritical fluid as a foaming agent to shape the raw materials into the micro-foamed self-healing material, which has the advantages of uniform foaming and more controllable foaming compared to chemical foaming; specifically includes the following steps: Step 1) Mix the raw materials and then melt-treat them to obtain a polymer melt; Step 2) Under a set pressure, inject the supercritical fluid into the polymer melt for mixing, so that the supercritical fluid is dissolved in the polymer melt; then reduce the pressure to allow the supercritical fluid to precipitate from the polymer melt to form bubbles, and obtain a foamed material; Step 3) The foamed material is cooled, solidified, and moisture-cured to obtain a micro-foamed self-healing material; wherein, since the cooling rate of the surface layer of the material is very fast, the foaming agent does not have enough time to form bubbles in the epidermis, so the surface is rapidly cooled and solidified to form a dense surface layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. The drawings described below are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0058] Figure 1 Schematic diagram of the self-repairing of the micro-foamed self-repairing material of the present invention;

[0059] Wherein: (a) is a schematic diagram of the structure of the micro-foam self-repairing material; (b) is a schematic diagram of the micro-foam self-repairing material with cracks; (c) is the micro-foam self-repairing material after self-repair;

[0060] The figures are marked as follows: 1-surface layer, 2-core layer, 3-external water vapor, 4-crack. DETAILED DESCRIPTION

[0061] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. The drawings described below are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0062] The invention provides a micro-foam self-repairing material, which comprises a surface layer and a core layer; wherein both the surface layer and the core layer have micropores; both the surface layer and the core layer are polymer matrices; and the polymer matrix comprises ABS resin and polyurethane resin.

[0063] The volume expansion ratio of the micro-foam self-repairing material is 2-60 times; the density of the micropores in the core layer is 1.0×10 6-1.0×10 15 Pieces / cm 3 ; The average pore size of the micropores in the core layer is 10-100μm.

[0064] The density of micropores in the surface layer is 1.0×10 9 -1.0×10 12 Pieces / cm 3 ; The average pore size of the micropores in the surface layer is 0.1-10μm; the thickness of the surface layer is 3-5mm.

[0065] On the other hand, the present invention provides a method for preparing any one of the micro-foam self-repairing materials, wherein the raw materials for preparing the micro-foam self-repairing material include, by weight:

[0066] 70-80 parts of ABS resin, 15-20 parts of polyurethane resin, 0.5-5 parts of compatibilizer, 1-2 parts of nucleating agent, 0.1-5 parts of antioxidant.

[0067] Among them, the relative molecular weight of ABS resin is 80,000-200,000; ABS resin is the main material of the air conditioner bottom shell or air conditioner drain pan to ensure the mechanical properties of the bottom shell, etc.

[0068] Polyurethane resin Polyurethane resin is a moisture-curable polyurethane resin (Polyurethane, PU), which is a high molecular polymer generated by the reaction of isocyanate groups (-NCO) and polyols (compounds containing multiple hydroxyl groups -OH). The basic structural unit of polyurethane is a carbamate bond (-NH-CO-O-). The molar ratio of isocyanate groups to polyols in polyurethane resin is 1.2-1.5:1 to ensure that there are still residual isocyanate groups (-NCO) after the polymerization is completed. The remaining isocyanate groups can react with moisture in the air or moisture on the surface of the substrate to form carbamate bonds and complete the surface curing.

[0069] The compatibilizer is one or more of a surfactant, a silane coupling agent, a maleic anhydride-modified polymer, and an acrylate; wherein the surfactant includes a polysiloxane and / or a polyether siloxane copolymer; the silane coupling agent includes γ-(methacryloyloxy)propyltrimethoxysilane and / or γ-aminopropyltriethoxysilane; the maleic anhydride-modified polymer includes one or more of maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, and maleic anhydride-grafted polystyrene; the compatibilizer can act as a compatible bridge, thereby improving the compatibility of ABS resin and polyurethane resin; for example, the acrylate segment in the polyurethane-acrylate copolymer (PU+MMA→PU-g-MMA) can interact with the acrylonitrile group in ABS, maleic anhydride (PU+MAH→PU-g-MAH), and silane coupling agent (ABS+SiRn+Xm→ABS-g-SiRn); new chemical groups are formed on the surface of polyurethane or ABS to enhance the interaction between the two.

[0070] The nucleating agent is an organic nucleating agent and / or an inorganic nucleating agent; wherein the organic nucleating agent includes a surfactant, 3-trimethoxysilylpropyl methacrylate, polyamide wax, and polyethylene wax; the inorganic nucleating agent includes a metal soap, talcum powder, silicon dioxide, and calcium carbonate; wherein the surfactant includes a polysiloxane and / or a polyether siloxane copolymer; the metal soap includes zinc stearate and / or calcium stearate; the nucleating agent can promote the nucleation and stabilization of bubbles in the polymer matrix, thereby affecting the pore structure of the final foaming material.

[0071] The antioxidant is one or more of phenolic antioxidants, phosphite antioxidants, and thioester antioxidants; wherein the phenolic antioxidants include 2,6-di-tert-butyl-4-methylphenol and / or tetraethyl bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate]; the phosphite antioxidants include N,N'-1,6-hexylene-bis-[3,5-di-tert-butyl-4-hydroxyphenylpropionamide] and / or tris(2,4-di-tert-butyl)phenyl phosphite; the thioester antioxidants include bis(2,6-di-tert-butyl-4-methylphenyl) sulfide phosphite; the antioxidants make up for the poor antioxidant properties of the polyurethane resin, improve the anti-aging properties of the bottom shell, and extend its service life.

[0072] The preparation method of the above-mentioned micro-foamed self-repairing material comprises the following steps:

[0073] Supercritical fluid is used as a foaming agent to shape the raw materials into micro-foamed self-repairing materials.

[0074] Specifically comprising: step 1) mixing the raw materials and then melting them to obtain a polymer melt;

[0075] The specific step is: ABS resin, polyurethane resin, compatibilizer, nucleating agent, antioxidant are mixed and added into an extruder, and the raw materials are heated and melted by the screw of the extruder to obtain a polymer melt; or

[0076] ABS resin, polyurethane resin, compatibilizer, nucleating agent and antioxidant are mixed and added to an extruder, the raw materials are heated and melted by the screw of the extruder, and then granulated to obtain masterbatch; the masterbatch is added to the extruder, the masterbatch is heated and melted by the screw of the extruder to obtain a polymer melt;

[0077] Among them, the heating temperature of the screw of the extruder is higher than the molten melting temperature of the raw material, which is set to 220°C-240°C in this application;

[0078] Step 2) injecting a supercritical fluid into a polymer melt under a set pressure for mixing, so that the supercritical fluid is dissolved in the polymer melt; then reducing the pressure to allow the supercritical fluid to precipitate from the polymer melt to form bubbles, and obtaining a foaming material;

[0079] The step is specifically as follows: under a set pressure, a supercritical fluid is injected into a polymer melt by a high-pressure pump, and the supercritical fluid swells and diffuses into the polymer melt for 1-5 minutes, so that the supercritical fluid is dissolved in the polymer melt; when the polymer and the supercritical fluid reach saturation, the pressure is rapidly reduced (i.e., a decompression treatment is performed, which is usually achieved by releasing a pressure valve). Due to the rapid drop in pressure, the supercritical fluid originally dissolved in the polymer suddenly becomes a supersaturated state, and rapidly precipitates from the polymer to form a large number of tiny bubbles. The formation of these bubbles is the result of a phase equilibrium change, resulting in a large number of micropores in the polymer matrix;

[0080] Among them, the supercritical fluid exists under high pressure in a state exceeding its critical temperature and pressure, which makes it have both a diffusion ability similar to that of gas and a solubility similar to that of liquid, and can penetrate and dissolve well in polymer materials. The supercritical fluid and the polymer are fully mixed and permeated, so that the polymer material reaches a saturated state. At this time, the supercritical fluid, as a foaming agent, has actually dissolved in the polymer to prepare for subsequent foaming; wherein, the supercritical fluid uses carbon dioxide or nitrogen; the decompression rate of the decompression treatment is 1-1000MPa / s; the set pressure is 10-15MPa;

[0081] Step 3) The foamed material is cooled, solidified, and moisture-cured to obtain a micro-foamed self-repairing material;

[0082] The specific steps are as follows: the foaming material is cooled and solidified in the mold to shape and stabilize the microporous structure; this stage may require specific cooling equipment and time to ensure the uniformity and stability of the microporous structure; after molding, it is solidified in a high humidity environment or a normal humidity environment to completely consume the isocyanate group (-NCO) on the surface of the material, making the surface a dense surface layer;

[0083] Among them, high humidity environment refers to an environment with a relative humidity of 80%-100% and a temperature of 20℃-30℃; conventional environment refers to an environment with a relative humidity of 30%-70% and a temperature of 20℃-30℃; the thickness of the surface layer and the thickness of the core layer can be regulated by parameters such as mold surface smoothness, cooling rate and cooling medium, and higher cooling efficiency usually leads to a thinner surface layer; in this application, the cooling rate is 25-45℃ / min, so that the thickness of the formed surface layer is 3-5mm, so as to ensure that the bottom shell has a certain mechanical strength;

[0084] Among them, the roughness (Ra) of the mold surface directly affects the smoothness and thickness of the surface layer; usually, the roughness of the mold surface is controlled at 0.1μm-1.0μm; 0.1μm is suitable for applications that require very high surface quality, such as optical lenses or precision parts; 0.5μm is suitable for most applications with high-quality surface requirements, such as automotive interior parts; 1.0μm: suitable for applications with general surface quality requirements, such as home appliance housings;

[0085] The cooling rate has a significant effect on the skin and core thickness; faster cooling rates generally result in thinner skin layers, while slower cooling rates result in thicker skin layers.

[0086] In another aspect, the present invention provides a bottom shell of an air conditioner, wherein the material of the bottom shell is any one of the above-mentioned micro-foamed self-repairing materials.

[0087] In another aspect, the present invention provides a method for preparing the above-mentioned air conditioner bottom case, comprising the following steps:

[0088] Step 1) mixing the raw materials and then melting them to obtain a polymer melt; wherein the raw materials include ABS resin, polyurethane resin, compatibilizer, nucleating agent, and antioxidant;

[0089] Step 2) Under a set pressure, a supercritical fluid is injected into a polymer melt for mixing to obtain a homogeneous solution; the homogeneous solution is injected into a mold of a bottom shell, and then decompressed to allow the supercritical fluid to precipitate from the homogeneous solution to form bubbles, thereby obtaining a foaming material;

[0090] Step 3) After the foaming material is cooled, solidified, and moisture-cured, a bottom shell is obtained.

[0091] In another aspect, the present invention provides an air conditioner, which includes the above-mentioned bottom casing.

[0092] The micro-foam self-repairing material is prepared into the bottom shell of the air conditioner. The micro-foam self-repairing material uses the moisture in the air or the moisture on the surface of the bottom shell as a reaction component to react with the isocyanate group (-NCO) in the polyurethane resin to form a carbamate bond, complete the curing process, and form Figure 1 The micro-foam self-healing material shown in (a) comprises a surface layer 1 and a core layer 2; wherein the polymerization reaction mechanism is: R-NCO+H2O→R-NH2+CO2; Figure 1 As shown in (b), when the bottom shell cracks, external water vapor 3 enters the crack, and the material absorbs water and expands to fill the crack 4, and fills the crack tip (at the crack tip, the stress level is significantly higher than the surrounding area, which is a key driving force for crack extension). After drying, the polyurethane resin will become a hard plastic, thereby repairing the crack of the bottom shell, as shown in FIG. Figure 1 (c) As shown; wherein, since polyurethane contains a large number of polar groups, it forms hydrogen bonds with water molecules (the main driving force for polyurethane to absorb water). The formation of hydrogen bonds allows water molecules to enter its molecular network, causing the material to absorb water and expand; the bottom shell of the air conditioner prepared from the above-mentioned micro-foamed self-repairing material does not need to be replaced or repaired with adhesive when cracked, the operation is simple, and it can avoid disassembly to damage other parts, thereby reducing costs; at the same time, this method will not affect the appearance of the bottom shell, and does not require any additional repair operations during use; it can be directly used in the manufacturing or maintenance process of the air conditioner, with low cost and relatively simple operation.

[0093] The micro-foam self-healing material of the present invention reduces the tip effect in the following ways:

[0094] Stress dispersion: The inherent pore structure of the micro-foam self-healing material can disperse the applied stress more evenly. The presence of pores can absorb and disperse stress and reduce the stress peak in the local area. This stress dispersion effect helps to delay the stress concentration in the defect area, thereby reducing the tip effect.

[0095] Changing the crack propagation path: The presence of pores can change the crack propagation path, making it more likely that the crack will propagate along the pore boundary during propagation, while the pore wall can slow down the crack propagation speed and reduce the tip strain energy, thereby alleviating the tip effect.

[0096] Increased toughness: The formation of microvoids is often accompanied by an increase in toughness. Higher toughness means that the material is able to absorb more energy instead of failing immediately at the tip fracture point, which directly helps to mitigate the tip effect.

[0097] Crack bridging: There are a large number of tiny pores in the micro-foamed self-healing material, which may form a crack bridging effect, that is, the two sides of the crack can maintain a certain degree of connection through the pore system, thereby inhibiting the crack propagation.

[0098] Among them, when the amount of polyurethane resin is high, although the impact resistance (i.e. toughness) of the material will be improved to a certain extent, the overall mechanical strength, thermal properties and chemical resistance will be attenuated to a certain extent, and the processing difficulty of the material will be increased to a certain extent.

[0099] The present invention is further described below with reference to specific embodiments and comparative examples.

[0100] Example 1

[0101] This embodiment provides a method for preparing a micro-foamed self-repairing material, comprising the following steps:

[0102] Step 1) ABS resin, polyurethane resin, compatibilizer, nucleating agent and antioxidant are mixed and added into an extruder for drying, preheating and prepressing, and melted after being heated by the screw of the extruder to obtain a polymer melt;

[0103] Among them, 80 parts of ABS resin; 15 parts of polyurethane resin (PU resin); 2 parts of compatibilizer; 2 parts of nucleating agent and 1 part of antioxidant; the relative molecular weight of ABS resin is 120,000; the molar ratio of isocyanate group to polyol in polyurethane resin is 1.2:1; the compatibilizer is acrylate, the nucleating agent is zinc stearate, and the antioxidant is tri(2,4-di-tert-butyl)phenyl phosphite; the screw heating temperature of the extruder is 220°C

[0104] Step 2) In the middle and rear sections of the extruder, a supercritical fluid is injected into the polymer melt by a high-pressure pump at a pressure of 15 MPa, and the supercritical fluid swells and diffuses into the polymer melt for 3 minutes to obtain a homogeneous solution; then the homogeneous solution is injected into the mold through a nozzle, and the pressure is quickly reduced by releasing the pressure valve (i.e., decompression treatment) to obtain a foaming material; wherein the decompression rate of the decompression treatment is 100 MPa / s;

[0105] Step 3) The foaming material is cooled and solidified in the mold, and solidified in a high humidity environment or a normal humidity environment after molding to obtain a micro-foamed self-repairing material; wherein the cooling rate is 40°C / min; and the thickness of the obtained surface layer is 4mm.

[0106] The micro-foam self-repairing material obtained in this embodiment includes a surface layer and a core layer; wherein both the surface layer and the core layer have micropores; both the surface layer and the core layer are polymer matrices; the polymer matrix includes ABS resin and polyurethane resin; the volume expansion ratio of the micro-foam self-repairing material is 45 times; the density of the micropores in the core layer is about 1.0×10 15Pieces / cm 3 The average pore size of the micropores in the core layer is 100 μm; the density of the micropores in the surface layer is about 1.0×10 10 Pieces / cm 3 ; The average pore size of the micropores in the surface layer is 6μm.

[0107] Example 2

[0108] This embodiment provides a method for preparing a bottom shell of an air conditioner, comprising the following steps:

[0109] Step 1) ABS resin, polyurethane resin, compatibilizer, nucleating agent and antioxidant are mixed and added into an extruder for drying, preheating and prepressing, and melted after being heated by the screw of the extruder to obtain a polymer melt;

[0110] Among them, 80 parts of ABS resin; 15 parts of polyurethane resin (PU resin); 2.5 parts of compatibilizer; 2 parts of nucleating agent and 0.5 parts of antioxidant; among them, the relative molecular weight of ABS resin is 200,000; the molar ratio of isocyanate group to polyol in polyurethane resin is 1.5:1; the compatibilizer is maleic anhydride grafted polypropylene (g-PP), the nucleating agent is talcum powder, and the antioxidant is tetraethyl bis [3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate]; the screw heating temperature of the extruder is 240°C;

[0111] Step 2) In the middle and rear sections of the extruder, a supercritical fluid is injected into the polymer melt by a high-pressure pump at a pressure of 5 MPa, and the supercritical fluid swells and diffuses into the polymer melt for 5 minutes to obtain a homogeneous solution; then the homogeneous solution is injected into the mold through a nozzle, and the pressure is quickly reduced by a pressure release valve (i.e., a decompression treatment is performed) to obtain a foaming material; wherein the decompression rate of the decompression treatment is 800 MPa / s;

[0112] Step 3) The foaming material is cooled and solidified in the mold, and solidified in a high humidity environment or a normal humidity environment after molding to obtain a micro-foamed self-repairing material; wherein the cooling rate is 30°C / min; and the thickness of the obtained surface layer is 3mm.

[0113] The micro-foam self-repairing material obtained in this embodiment includes a surface layer and a core layer; wherein both the surface layer and the core layer have micropores; both the surface layer and the core layer are polymer matrices; the polymer matrix includes ABS resin and polyurethane resin; the volume expansion ratio of the micro-foam self-repairing material is 20 times; the density of the micropores in the core layer is about 1.0×10 12 Pieces / cm 3 The average pore size of the micropores in the core layer is 50 μm; the density of the micropores in the surface layer is 1.0×10 9 Pieces / cm 3 ; The average pore size of the micropores in the surface layer is 2μm.

[0114] Comparative Example 1

[0115] This comparative example provides a method for preparing a micro-foamed self-repairing material, comprising the following steps:

[0116] Step 1) ABS resin, polyurethane resin, compatibilizer, nucleating agent and antioxidant are mixed and added into an extruder for drying, preheating and prepressing, and melted after being heated by the screw of the extruder to obtain a polymer melt;

[0117] Among them, ABS resin 90 parts; polyurethane resin (PU resin) 5 parts; compatibilizer 2 parts; nucleating agent 2 parts, antioxidant 1 part; wherein the relative molecular weight of ABS resin is 120,000; the molar ratio of isocyanate group to polyol in polyurethane resin is 1.2:1; the compatibilizer is acrylate, the nucleating agent is zinc stearate, and the antioxidant is tri(2,4-di-tert-butyl)phenyl phosphite; the screw heating temperature of the extruder is 220°C

[0118] Step 2) In the middle and rear sections of the extruder, a supercritical fluid is injected into the polymer melt by a high-pressure pump at a pressure of 15 MPa, and the supercritical fluid swells and diffuses into the polymer melt for 3 minutes to obtain a homogeneous solution; then the homogeneous solution is injected into the mold through a nozzle, and the pressure is quickly reduced by releasing the pressure valve (i.e., decompression treatment) to obtain a foaming material; wherein the decompression rate of the decompression treatment is 100 MPa / s;

[0119] Step 3) The foaming material is cooled and solidified in the mold, and solidified in a high humidity environment or a normal humidity environment after molding to obtain a micro-foamed self-repairing material; wherein the cooling rate is 40°C / min; and the thickness of the obtained surface layer is 4mm.

[0120] Comparative Example 2

[0121] This comparative example provides a method for preparing a micro-foamed self-repairing material, comprising the following steps:

[0122] Step 1) ABS resin, polyurethane resin, compatibilizer, nucleating agent and antioxidant are mixed and added into an extruder for drying, preheating and prepressing, and melted after being heated by the screw of the extruder to obtain a polymer melt;

[0123] Among them, ABS resin 70 parts; polyurethane resin (PU resin) 25 parts; compatibilizer 2 parts; nucleating agent 2 parts, antioxidant 1 part; wherein, the relative molecular weight of ABS resin is 120,000; the molar ratio of isocyanate group to polyol in polyurethane resin is 1.2:1; the compatibilizer is acrylate, the nucleating agent is zinc stearate, and the antioxidant is tri(2,4-di-tert-butyl)phenyl phosphite; the screw heating temperature of the extruder is 220°C

[0124] Step 2) In the middle and rear sections of the extruder, a supercritical fluid is injected into the polymer melt by a high-pressure pump at a pressure of 15 MPa, and the supercritical fluid swells and diffuses into the polymer melt for 3 minutes to obtain a homogeneous solution; then the homogeneous solution is injected into the mold through a nozzle, and the pressure is quickly reduced by releasing the pressure valve (i.e., decompression treatment) to obtain a foaming material; wherein the decompression rate of the decompression treatment is 100 MPa / s;

[0125] Step 3) The foaming material is cooled and solidified in the mold, and solidified in a high humidity environment or a normal humidity environment after molding to obtain a micro-foamed self-repairing material; wherein the cooling rate is 40°C / min; and the thickness of the obtained surface layer is 4mm.

[0126] The molds of the above embodiments and comparative examples are bottom shell molds of air conditioners, so the obtained micro-foamed self-repairing material is the bottom shell. The performances of the corresponding bottom shell and the existing bottom shell (obtained by injection molding of ABS resin) are tested, and the results are shown in Table 1.

[0127] Table 1

[0128]

[0129] It can be seen that compared with the bottom shell of the existing air conditioner, the bottom shell of the air conditioner obtained in the embodiment has mechanical properties equivalent to those of the existing bottom shell, but the crack propagation is slower; this is because when the bottom shell of the embodiment cracks, external water vapor enters the crack, and the material absorbs water and expands to fill the crack and fill the crack tip (at the crack tip, the stress level is significantly higher than that in the surrounding area, which is a key driving force for crack propagation), and the polyurethane resin will become a hard plastic after drying to prevent further crack propagation; compared with Comparative Example 1, the crack propagation of the bottom shell of the air conditioner obtained in the embodiment is slower, this is because the content of polyurethane resin in Comparative Example 1 is relatively low, and the self-repair function cannot be achieved or the repair effect is deteriorated; compared with Comparative Example 2, the tensile strength of the bottom shell of the air conditioner obtained in the embodiment is better, this is because the amount of polyurethane resin in Comparative Example 2 is relatively high, although the impact resistance (i.e., toughness) of the material will be improved to a certain extent, but the overall mechanical strength, thermal properties and chemical resistance will be attenuated to a certain extent, and the processing difficulty of the material will be increased to a certain extent.

[0130] The above embodiments 1 and 2 are preferred embodiments of the present application, and the following embodiments are embodiments that adopt non-essential technical features of the present application.

[0131] Example 3

[0132] This embodiment provides a method for preparing a micro-foamed self-repairing material, comprising the following steps:

[0133] Step 1) ABS resin, polyurethane resin, compatibilizer, nucleating agent and antioxidant are mixed and added into an extruder for drying, preheating and prepressing, and melted after being heated by the screw of the extruder to obtain a polymer melt;

[0134] Among them, 80 parts of ABS resin; 15 parts of polyurethane resin (PU resin); 2 parts of compatibilizer; 2 parts of nucleating agent and 1 part of antioxidant; the relative molecular weight of ABS resin is 120,000; the molar ratio of isocyanate group to polyol in polyurethane resin is 0.8:1; the compatibilizer is acrylate, the nucleating agent is zinc stearate, and the antioxidant is tri(2,4-di-tert-butyl)phenyl phosphite; the screw heating temperature of the extruder is 220°C

[0135] Step 2) In the middle and rear sections of the extruder, a supercritical fluid is injected into the polymer melt by a high-pressure pump at a pressure of 15 MPa, and the supercritical fluid swells and diffuses into the polymer melt for 3 minutes to obtain a homogeneous solution; then the homogeneous solution is injected into the mold through a nozzle, and the pressure is quickly reduced by releasing the pressure valve (i.e., decompression treatment) to obtain a foaming material; wherein the decompression rate of the decompression treatment is 100 MPa / s;

[0136] Step 3) The foaming material is cooled and solidified in the mold, and solidified in a high humidity environment or a normal humidity environment after molding to obtain a micro-foamed self-repairing material; wherein the cooling rate is 40°C / min; and the thickness of the obtained surface layer is 4mm.

[0137] Example 4

[0138] This embodiment provides a method for preparing a micro-foamed self-repairing material, comprising the following steps:

[0139] Step 1) ABS resin, polyurethane resin, compatibilizer, nucleating agent and antioxidant are mixed and added into an extruder for drying, preheating and prepressing, and melted after being heated by the screw of the extruder to obtain a polymer melt;

[0140] Among them, 80 parts of ABS resin; 15 parts of polyurethane resin (PU resin); 2 parts of compatibilizer; 2 parts of nucleating agent and 1 part of antioxidant; the relative molecular weight of ABS resin is 120,000; the molar ratio of isocyanate group to polyol in polyurethane resin is 1.2:1; the compatibilizer is acrylate, the nucleating agent is zinc stearate, and the antioxidant is tri(2,4-di-tert-butyl)phenyl phosphite; the screw heating temperature of the extruder is 220°C

[0141] Step 2) In the middle and rear sections of the extruder, a supercritical fluid is injected into the polymer melt by a high-pressure pump at a pressure of 15 MPa, and the supercritical fluid swells and diffuses into the polymer melt for 3 minutes to obtain a homogeneous solution; then the homogeneous solution is injected into the mold through a nozzle, and the pressure is quickly reduced by releasing the pressure valve (i.e., decompression treatment) to obtain a foaming material; wherein the decompression rate of the decompression treatment is 100 MPa / s;

[0142] Step 3) The foaming material is cooled and solidified in the mold, and solidified in a high humidity environment or a normal humidity environment after molding to obtain a micro-foamed self-repairing material; wherein the cooling rate is 15°C / min; and the thickness of the obtained surface layer is 8mm.

[0143] Example 5

[0144] This embodiment provides a method for preparing a micro-foamed self-repairing material, comprising the following steps:

[0145] Step 1) ABS resin, polyurethane resin, compatibilizer, nucleating agent and antioxidant are mixed and added into an extruder for drying, preheating and prepressing, and melted after being heated by the screw of the extruder to obtain a polymer melt;

[0146] Among them, 80 parts of ABS resin; 15 parts of polyurethane resin (PU resin); 2 parts of compatibilizer; 2 parts of nucleating agent and 1 part of antioxidant; the relative molecular weight of ABS resin is 120,000; the molar ratio of isocyanate group to polyol in polyurethane resin is 1.2:1; the compatibilizer is acrylate, the nucleating agent is zinc stearate, and the antioxidant is tri(2,4-di-tert-butyl)phenyl phosphite; the screw heating temperature of the extruder is 220°C

[0147] Step 2) In the middle and rear sections of the extruder, a supercritical fluid is injected into the polymer melt by a high-pressure pump at a pressure of 15 MPa, and the supercritical fluid swells and diffuses into the polymer melt for 3 minutes to obtain a homogeneous solution; then the homogeneous solution is injected into the mold through a nozzle, and the pressure is quickly reduced by releasing the pressure valve (i.e., decompression treatment) to obtain a foaming material; wherein the decompression rate of the decompression treatment is 100 MPa / s;

[0148] Step 3) The foaming material is cooled and solidified in the mold, and solidified in a high humidity environment or a normal humidity environment after molding to obtain a micro-foamed self-repairing material; wherein the cooling rate is 55°C / min; and the thickness of the obtained surface layer is 1.5 mm.

[0149] The mold in Examples 3-5 is a bottom shell mold of an air conditioner, so the obtained micro-foamed self-repairing material is a bottom shell. The performance of the corresponding bottom shell is tested, and the results are shown in Table 2.

[0150] Table 2

[0151] Test items Example 3 Example 4 Example 5 density <![CDATA[0.8g / cm 3 ]]> <![CDATA[0.8g / cm 3 ]]> <![CDATA[0.8g / cm 3 ]]> Tensile Strength 30MPa 30MPa 28MPa Impact strength <![CDATA[10KJ / m 2 ]]> <![CDATA[8KJ / m 2 ]]> <![CDATA[11KJ / m 2 ]]> Crack growth rate <![CDATA[10 -6 mm / cycle]]> <![CDATA[10 -6 mm / cycle]]> <![CDATA[10 -6 mm / cycle]]>

[0152] Combining Table 1 and Table 2, it can be seen that compared with Example 1, in Example 3, the molar ratio of isocyanate groups to polyols is lower, that is, the isocyanate groups are less, so it is impossible to utilize the reaction of water and the isocyanate groups in the polyurethane resin to form urethane bonds and complete the curing process, so it is difficult to form a dense surface layer; in Example 4, the cooling rate of 15°C is too slow, and the surface layer of the obtained bottom shell is thicker, forming a dense, high hardness layer, but lacks toughness, and the internal pore structure of the surface layer is uneven, with a mixture of large and small pores, and it is easy to break at stress concentration points; in Example 5, the cooling rate is too fast, and the surface layer of the obtained bottom shell is thinner, the formed surface hardness is lower, the protective effect is limited, and the internal pore structure of the surface layer is uneven, with a large number of tiny holes, affecting the overall strength.

[0153] It is easy for those skilled in the art to understand that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0154] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention. The above description is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present invention. These improvements and variations should also be regarded as the protection scope of the present invention.

Claims

1. A micro-foamed self-repairing material, characterized in that: The micro-foamed self-repairing material comprises a surface layer and a core layer; wherein the surface layer and the core layer both have micropores; the surface layer and the core layer are both polymer matrices; the polymer matrix comprises ABS resin and polyurethane resin.

2. The micro-foamed self-repairing material according to claim 1, characterized in that: The density of micropores in the core layer is 1.0×10 6 -1.0×10 15 Pieces / cm 3 ; and / or The average pore size of the micropores in the core layer is 10-100 μm; and / or The volume expansion ratio of the micro-foamed self-repairing material is 2-60 times.

3. The micro-foamed self-repairing material according to claim 1 or 2, characterized in that: The density of micropores in the surface layer is 1.0×10 9 -1.0×10 12 Pieces / cm 3 ; and / or The average pore size of the micropores in the surface layer is 0.1-10 μm; and / or The thickness of the surface layer is 3-5 mm.

4. The method for preparing the micro-foamed self-repairing material according to any one of claims 1 to 3, characterized in that: The raw materials for preparing the micro-foamed self-repairing material include, by weight: 70-80 parts of ABS resin, 15-20 parts of polyurethane resin, 0.5-5 parts of compatibilizer, 1-2 parts of nucleating agent, 0.1-5 parts of antioxidant.

5. The method for preparing the micro-foamed self-repairing material according to claim 4, characterized in that: The relative molecular weight of the ABS resin is 80,000-200,000.

6. The method for preparing the micro-foamed self-repairing material according to claim 4, characterized in that: The polyurethane resin is a moisture curable polyurethane resin; and / or The molar ratio of isocyanate groups to polyols in the polyurethane resin is 1.2-1.5:

1.

7. The method for preparing the micro-foamed self-repairing material according to claim 4, characterized in that: The compatibilizer is one or more of a surfactant, a silane coupling agent, a maleic anhydride modified polymer, and an acrylate.

8. The method for preparing the micro-foamed self-repairing material according to claim 7, characterized in that: The surfactant comprises polysiloxane and / or polyether siloxane copolymer; and / or The silane coupling agent includes γ-(methacryloyloxy)propyltrimethoxysilane and / or γ-aminopropyltriethoxysilane; and / or The maleic anhydride modified polymer includes one or more of maleic anhydride grafted polyethylene, maleic anhydride grafted polypropylene, and maleic anhydride grafted polystyrene.

9. The method for preparing the micro-foamed self-repairing material according to claim 4, characterized in that: The nucleating agent is an organic nucleating agent and / or an inorganic nucleating agent; Wherein, the organic nucleating agent includes one or more of surfactant, 3-trimethoxysilylpropyl methacrylate, polyamide wax, and polyethylene wax; The inorganic nucleating agent includes one or more of metal soap, talc, silicon dioxide, and calcium carbonate.

10. The method for preparing the micro-foamed self-repairing material according to claim 9, characterized in that: The surfactant comprises polysiloxane and / or polyether siloxane copolymer; and / or The metal soap includes zinc stearate and / or calcium stearate.

11. The method for preparing the micro-foamed self-repairing material according to claim 4, characterized in that: The antioxidant is one or more of phenolic antioxidants, phosphite antioxidants, and thioester antioxidants.

12. The method for preparing the micro-foamed self-repairing material according to claim 11, characterized in that: The phenolic antioxidant includes 2,6-di-tert-butyl-4-methylphenol and / or tetraethyl bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate]; and / or The phosphite antioxidant includes N,N'-1,6-hexylene-bis-[3,5-di-tert-butyl-4-hydroxyphenylpropionamide] and / or tris(2,4-di-tert-butyl)phenyl phosphite; and / or The thioester antioxidant includes bis(2,6-di-tert-butyl-4-methylphenyl)sulfurized phosphite.

13. The method for preparing a micro-foamed self-repairing material according to any one of claims 4 to 12, characterized in that: The preparation method comprises the following steps: The raw material is formed into the micro-foamed self-repairing material by using a supercritical fluid as a foaming agent.

14. The method for preparing the micro-foamed self-repairing material according to claim 13, characterized in that: The step of molding the raw material into the micro-foamed self-repairing material comprises: Step 1) mixing the raw materials and then melting them to obtain a polymer melt; Step 2) injecting a supercritical fluid into the polymer melt under a set pressure for mixing, so that the supercritical fluid is dissolved in the polymer melt; then reducing the pressure to allow the supercritical fluid to precipitate from the polymer melt to form bubbles, and obtain a foaming material; Step 3) The foaming material is cooled, solidified, and moisture-cured to obtain the micro-foamed self-repairing material.

15. The method for preparing the micro-foamed self-repairing material according to claim 14, characterized in that: In the step 1): The ABS resin, polyurethane resin, compatibilizer, nucleating agent and antioxidant are mixed and added into an extruder, and the raw materials are heated and melted by the screw of the extruder to obtain a polymer melt; or The ABS resin, polyurethane resin, compatibilizer, nucleating agent and antioxidant are mixed and added to an extruder, the raw materials are heated and melted by the screw of the extruder, and then granulated to obtain master batches; the master batches are added to an extruder, the master batches are heated and melted by the screw of the extruder to obtain a polymer melt.

16. The method for preparing the micro-foamed self-repairing material according to claim 15, characterized in that: The heating temperature of the screw of the extruder is 220°C-240°C.

17. The method for preparing the micro-foamed self-repairing material according to claim 14, characterized in that: Under a set pressure, the supercritical fluid is injected into the polymer melt by a high-pressure pump, and the supercritical fluid swells and diffuses into the polymer melt for 1-5 minutes, so that the supercritical fluid is dissolved in the polymer melt; and / or The supercritical fluid is separated from the polymer melt by reducing the pressure through a pressure release valve.

18. The method for preparing a micro-foamed self-repairing material according to any one of claims 14 to 17, characterized in that: The supercritical fluid is carbon dioxide or nitrogen; and / or The decompression rate of the decompression treatment is 1-1000 MPa / s; and / or The set pressure is 10-15 MPa; and / or The cooling speed is 25-45°C / min.

19. A bottom case of an air conditioner, characterized in that: The material of the bottom shell is the micro-foamed self-repairing material described in claim 1.

20. The method for preparing the bottom shell according to claim 19, characterized in that: The following steps are involved: Step 1) mixing the raw materials and then melting them to obtain a polymer melt; wherein the raw materials include ABS resin, polyurethane resin, compatibilizer, nucleating agent, and antioxidant; Step 2) Under a set pressure, a supercritical fluid is injected into the polymer melt for mixing to obtain a homogeneous solution; the homogeneous solution is injected into a mold of a bottom shell, and then decompressed to allow the supercritical fluid to precipitate from the homogeneous solution to form bubbles, thereby obtaining a foaming material; Step 3) After the foaming material is cooled, solidified, and moisture-cured, the bottom shell is obtained.

21. An air conditioner, characterized in that: The air conditioner includes the bottom case of claim 19.

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