Composite material, preparation method thereof and refrigerator

Abstract

The invention discloses a composite material, a preparation method thereof and a refrigerator. The composite material is prepared from the following raw materials: modified anion mineral powder, polypropylene, a compatilizer and a degradation agent, wherein the modified negative ion mineral powder comprises negative ion mineral powder and epoxy group-containing resin coated on the negative ion mineral powder. According to the composite material disclosed by the invention, through the combined action of the anion mineral powder coated with the epoxy group-containing resin, the compatilizer and the degradation agent, the compatibility and the dispersity of the anion mineral powder and the polypropylene material are improved, so that the production yield and the mechanical property of the composite material are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer materials, and in particular to a composite material, a preparation method thereof and a refrigerator. BACKGROUND

[0002] Negative ions are particles with negative charges, which can effectively purify air and remove harmful substances such as bacteria, viruses, dust and odors. Negative ion mineral materials have the function of releasing negative ions, but the compatibility of negative ion mineral materials with high polymer materials is poor, and direct mixing can easily cause uneven dispersion and agglomeration of negative ion mineral materials, resulting in unstable release of negative ions and thus reducing the use performance of high polymer materials. SUMMARY

[0003] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, one object of the present application is to provide a composite material, which improves the compatibility and dispersibility of negative ion mineral powder with polypropylene material through the combined action of the epoxy-containing resin coated on the negative ion mineral powder, the compatibilizer and the degrading agent, thereby improving the production yield and mechanical properties of the composite material.

[0004] A second object of the present application is to provide a preparation method of the above-mentioned composite material.

[0005] A third object of the present application is to provide a refrigerator using the above-mentioned composite material.

[0006] According to the composite material of the first aspect of the present application, the raw materials for forming the composite material include modified negative ion mineral powder, polypropylene, compatibilizer and degrading agent. The modified negative ion mineral powder includes negative ion mineral powder and epoxy-containing resin coated on the negative ion mineral powder.

[0007] According to the composite material of the present application, the compatibility and dispersibility of negative ion mineral powder with polypropylene material are improved through the combined action of the epoxy-containing resin coated on the negative ion mineral powder, the compatibilizer and the degrading agent, and the release amount and stability of negative ions of the composite material are also improved, thereby improving the production yield and mechanical properties of the composite material. When the composite material is applied to the inner shell of a household appliance (such as the inner shell of a refrigerator), the stable and long-acting release of negative ions is conducive to achieving long-acting antibacterial, purifying and fresh-keeping effects on the storage space of the household appliance, thereby improving the use performance of the household appliance.

[0008] According to some embodiments of the present application, the raw materials for forming the composite material include 1%-20% modified negative ion mineral powder, 70%-95% polypropylene, 3%-10% compatibilizer and 0.6%-1% degrading agent by mass percentage.

[0009] The specific advantages or beneficial effects in the above scheme are as follows: in the raw materials for forming the composite material, the mass ratio of each component of the modified negative ion ore powder, polypropylene, compatibilizer and degrading agent is reasonably set, which is beneficial to the reaction of polypropylene, modified negative ion ore powder and degrading agent, and is beneficial to the performance of the compatibilizer and the degrading agent, effectively improving the compatibility of each component in the raw materials of the composite material, so that the modified negative ion ore powder is not easy to agglomerate, and each component is uniformly dispersed, thereby effectively improving the long-acting property and stability of the negative ion release, and improving the long-term antibacterial and purification effect of the composite material. Moreover, the modified negative ion ore powder has heterogeneous nucleation effect, which can promote the formation of fine grains of polypropylene, thereby improving the structural strength of the composite material, reducing the risk of cracking of the composite material during use, and prolonging the service life of the composite material product. In addition, the mechanical properties (such as bending strength, tensile strength and impact strength) of the composite material can be ensured, the probability of stress fracture of the parts made of the composite material during use can be reduced, and the use performance of the composite material is improved.

[0010] According to some embodiments of the application, the negative ion ore powder comprises tourmaline and / or opal shale; preferably, the negative ion ore powder comprises tourmaline; and / or The polypropylene comprises homopolymer polypropylene and / or copolymer polypropylene; preferably, the polypropylene comprises copolymer polypropylene, and the melt index is 20 g / 10 min-60 g / 10 min; and / or The compatibilizer comprises at least one of polypropylene grafted maleic anhydride, polypropylene grafted acrylic acid, polypropylene grafted hydroxyethyl methacrylate, polypropylene grafted glycidyl methacrylate, ethylene-vinyl acetate copolymer, polyolefin elastomer, amino silane, epoxy silane, methacryloyl silane, phthalate coupling agent and aluminate coupling agent; preferably, the compatibilizer comprises polypropylene grafted maleic anhydride; and / or The degrading agent comprises dicumyl peroxide, sodium hydroxide and zinc chloride, the mass ratio of the sodium hydroxide and the zinc chloride is (1:1)-(1:2), and the mass ratio of the dicumyl peroxide in the composite material is 0.1%-0.5%; preferably, the mass ratio of the sodium hydroxide and the zinc chloride is 3:5.

[0011] The specific advantages or beneficial effects in the above scheme are as follows: in the raw materials for forming the composite material, the material selection of the negative ion ore powder, polypropylene, compatibilizer and degrading agent is reasonable, which effectively improves the compatibility between each component in the composite material, thereby improving the dispersion uniformity of each component and the use performance of the composite material. Moreover, the processing difficulty can be reduced, the production yield of the composite material can be improved, and the production cost can be reduced. In addition, by adjusting the melt index of the polypropylene material and the mass ratio of the sodium hydroxide and the zinc chloride, the compatibility between each component of the composite material is further improved, the production difficulty is reduced, and the comprehensive use performance of the composite material is improved.

[0012] According to some embodiments of the present application, the raw materials for forming the composite material further include, in percentage by mass: 0.3%-1% antioxidant, 0.1%-1% antibacterial agent.

[0013] The specific advantages or benefits in the above scheme are as follows: by adding an antioxidant to the raw materials of the composite material, thermal oxidative degradation in the processing process can be effectively inhibited, the production yield of the composite material is improved, thereby reducing the production cost and improving the production efficiency. Moreover, it is also beneficial to improve the mechanical properties of the composite material, delay aging during the processing and storage of the composite material, thereby prolonging the service life of the composite material product. At the same time, by adding an antibacterial agent, a synergistic antibacterial effect with the antibacterial effect of negative ion release is achieved, the long-term antibacterial effect of the composite material product is effectively improved, and the composite material has long-acting antibacterial property. In addition, the production cost can be controlled under the premise of ensuring the use performance of the composite material.

[0014] According to some embodiments of the present application, the antioxidant includes at least one of a phenolic antioxidant, a phosphite antioxidant, and a hindered amine antioxidant; and / or The antibacterial agent includes at least one of a silver-based antibacterial agent, a zinc-based antibacterial agent, a quaternary ammonium salt-based antibacterial agent, and a chitosan-based antibacterial agent; preferably, the antibacterial agent includes a silver-loaded zirconium phosphate antibacterial agent.

[0015] The specific advantages or benefits in the above scheme are as follows: by selecting a suitable antioxidant, the oxidative degradation of polypropylene can be effectively delayed, the cracking and pulverization of the composite material product caused by aging can be effectively reduced, and the service life is prolonged. At the same time, by selecting a suitable antibacterial agent, the long-acting and stable antibacterial effect of the composite material can be effectively improved, and a synergistic effect with the antibacterial effect generated by the release of negative ions is formed, thereby effectively inhibiting the floating bacteria in the air and the bacteria attached to the surface of the material, effectively improving the user safety, and expanding the application prospect of the composite material in the household appliance field.

[0016] The preparation method of the polyurethane hot melt adhesive according to the above-mentioned first aspect of the present application comprises the following steps: The negative ion mineral powder and the epoxy-based resin solution are mixed, a curing agent is added, and after defoaming treatment under vacuum conditions, stepwise curing treatment is performed to obtain modified negative ion mineral powder; The modified negative ion mineral powder, polypropylene, a compatibilizer, and a degradation agent are mixed in the content to obtain a first mixture; The first mixture is melt-extruded in a screw extruder to prepare the composite material.

[0017] The specific advantages or beneficial effects in the above scheme are as follows: in the preparation process of the modified negative ion mineral powder, through the defoaming treatment, the air bubbles or dissolved gas mixed in the system are eliminated, so as to eliminate the surface defects of the modified negative ion mineral powder, improve the internal density, and optimize the performance of the composite material. At the same time, the stepwise curing treatment can improve the uniformity of the coating of the epoxy-based resin on the surface of the negative ion mineral powder, ensure the uniformity and stability of the negative ion release, and improve the performance of the composite material. Moreover, it can also avoid the crystal structure phase change (such as dehydration, lattice distortion) or surface active site inactivation of the negative ion mineral powder under high temperature conditions, thereby improving the release rate of the negative ion of the composite material and prolonging the performance of the composite material. In addition, the preparation method is simple, which is conducive to improving the production efficiency and reducing the production cost.

[0018] According to some embodiments of the present application, the mixing of the negative ion mineral powder and the epoxy-based resin solution, the addition of the curing agent, the defoaming treatment under vacuum conditions, and the stepwise curing treatment specifically include: mixing the negative ion mineral powder and nano cerium oxide and then drying to obtain a second mixture; mixing the epoxy resin and the first solvent to obtain the epoxy-based resin solution; mixing the second mixture and the epoxy-based resin solution, adding the curing agent, defoaming under vacuum conditions for a second time, and then performing stepwise curing treatment; grinding the material after the stepwise curing treatment to obtain the modified negative ion mineral powder.

[0019] The specific advantages or beneficial effects in the above scheme are as follows: the modified negative ion mineral powder prepared through the above reaction process is uniformly coated with epoxy resin, has uniform particle size, and has a larger specific surface area, which can be more fully contacted with air or water, thereby improving the negative ion release concentration and reaction efficiency, and improving the performance of the composite material. In addition, it is also conducive to improving the dispersibility of the modified negative ion mineral powder and avoiding agglomeration, thereby improving the mechanical properties of the composite material and enhancing the strength of the composite material.

[0020] According to some embodiments of the present application, the conditions of the stepwise curing treatment include: successively incubating at 70-90℃ for 1-3h, at 110-130℃ for 1-3h, and at 140-160℃ for 0.5-2h.

[0021] The specific advantages or beneficial effects in the above scheme are as follows: the stepwise curing treatment controls the temperature at each stage to make the reaction heat uniform, gradually improve the crosslinking density, and form a more regular and uniform three-dimensional network structure, which is conducive to improving the interfacial bonding force between the epoxy resin and the negative ion mineral powder, thereby improving the mechanical properties of the modified negative ion mineral powder.

[0022] According to some embodiments of the present application, the segment sets the processing temperature in the screw extruder, which is 150-180℃, 190-210℃ and 200-220℃ in turn; and / or The rotation speed of the screw extruder is 250-600rpm.

[0023] The specific advantages or beneficial effects in the above scheme are as follows: by setting the screw extruder extrusion temperature gradient and limiting the rotation speed range of the screw extruder, the processing temperature in the screw extruder at different stages can be matched, the shear strength in the extrusion process is improved, the mechanical strength of the composite material is improved, the crack fracture of the composite material product caused by external force in the use process is reduced, and the service life is prolonged. At the same time, the reverse conveying thread element is added in the middle and later stages of the screw extrusion, the polymerization reaction efficiency of the modified negative ion mineral powder and polypropylene is improved, the compatibility and dispersity of the modified negative ion mineral powder and polypropylene material are improved, and then the stability and uniformity of the negative ion release of the composite material are improved.

[0024] According to the refrigerator of the third aspect of the embodiments of the present application, comprising: A cabinet body, the cabinet body is formed with an opening; A cabinet door, the cabinet door is arranged at the opening, for opening and closing the opening, the cabinet body and the cabinet door jointly define a containing space; The refrigerator further comprises: A drawer, the drawer comprises the composite material according to the first aspect of the embodiments described above, or the composite material prepared by the preparation method according to the second aspect of the embodiments described above; and / or The cabinet body comprises an inner shell, the inner shell is configured as an inner wall surface of the containing space, Wherein, the inner shell comprises the composite material according to the first aspect of the embodiments described above, or the composite material prepared by the preparation method according to the second aspect of the embodiments described above.

[0025] The specific advantages or beneficial effects in the above scheme are as follows: the drawer and the inner shell are made of composite material, so that long-term and stable bacteriostatic effect on the storage space can be achieved without the need for additional antibacterial agents, which is conducive to improving the user safety. Moreover, the composite material can stably release negative ions to adjust the humidity distribution of the containing space of the refrigerator, thereby improving the preservation effect of the stored items (such as fruits, vegetables, etc.) in the refrigerator, prolonging the storage time of the stored items, and improving the user experience. In addition, it can also replace the negative ion module used in traditional refrigerators, without ozone generation, improve the environmental protection effect of the refrigerator, and improve the comprehensive use performance of the refrigerator.

[0026] Additional aspects and advantages of the application will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or can be learned by practice of the application. DETAILED DESCRIPTION

[0027] The embodiments of the present application are described in detail below, and the composite material according to the embodiments of the present application is described below. According to the embodiments of the first aspect of the present application, the raw materials for forming the composite material include modified negative ion ore powder, polypropylene, a compatibilizer, and a degradation agent. The modified negative ion ore powder includes negative ion ore powder and an epoxy group-containing resin coated on the negative ion ore powder.

[0028] For example, the modified negative ion ore powder is obtained by coating an epoxy group-containing resin on the outside of the negative ion ore powder with the negative ion ore powder as the core. That is, the epoxy group-containing resin is coated on the outside of the negative ion ore powder to form the modified negative ion ore powder with a core-shell structure. The epoxy group-containing resin has a shrinkage stress during the curing process, which exerts a pressing force on the tourmaline, for example, to form a stress-induced strengthening effect. As a result, the functional crystal surface of the tourmaline for releasing negative ions is preferentially exposed in water and oxygen, the lattice distortion is increased, the spontaneous polarization intensity is enhanced, and the negative ion release capacity is improved. In addition, the epoxy group-containing resin has a high volume resistivity, which is beneficial to the extension of the duration of the spontaneous polarization electric field of the tourmaline, thereby enhancing the efficiency of the dissociation of water molecules, and a micro-capacitance structure is formed at the interface between the resin layer and the tourmaline, which further concentrates the electrostatic field and promotes the ionization of water to form negative oxygen ions. Moreover, the coating of the epoxy group-containing resin reduces the agglomeration of the negative ion ore powder, which is more uniformly dispersed in the resin matrix, increases the effective action area, and is more conducive to the release of negative ions and improves the uniformity of the release.

[0029] Based on the above interaction mechanism, the spatial release uniformity of negative ions of the negative ion ore powder is improved through the coating of the epoxy group-containing resin and the synergistic effect of nano cerium oxide. Moreover, the mechanical strength of the negative ion ore powder is low, and it is easy to be broken due to mechanical stress during the processing of the composite material, thereby reducing the stability of the release of negative ions. The coating layer of the epoxy group-containing resin can enhance the mechanical strength of the negative ion ore powder, thereby reducing the breakage or structural damage during processing and ensuring the stability of the release of negative ions of the composite material, maintaining the structure of the ore powder itself without being damaged, avoiding the problems of short-term high release and long-term decay, improving the stability of the release amount, and improving the overall performance.

[0030] In the present application, by adding the compatibilizer in the raw material of the composite material, the polypropylene molecular chain is broken to form an allyl double bond, which can polymerize with the epoxy active group in the epoxy-containing resin, effectively improving the compatibility of the modified negative ion ore powder and the polypropylene, and improving the comprehensive use performance of the composite material. In addition, the raw material for forming the composite material also includes a degradation agent. The addition of the degradation agent causes the epoxy-containing resin to undergo slight depolymerization to form active reaction groups and polymerize with the polypropylene, thereby improving the compatibility and dispersibility of the modified negative ion ore powder and the polypropylene material, and further improving the stability and uniformity of the negative ion release of the composite material, and improving the comprehensive use performance of the composite material.

[0031] Therefore, by adding the compatibilizer and the degradation agent in the raw material of the composite material, the compatibility and dispersibility of the modified negative ion ore powder and the polypropylene material are effectively improved, thereby improving the dispersion uniformity of the modified negative ion ore powder in the composite material, and further improving the stability and uniformity of the negative ion release of the composite material, and improving the comprehensive use performance of the composite material.

[0032] In addition, when the composite material is applied to the inner shell of a household appliance (such as the inner shell of a refrigerator or a drawer), it is beneficial to achieve long-acting antibacterial, purification and preservation effects on the storage space inside the refrigerator, thereby improving the use performance of the household appliance.

[0033] According to the composite material of the embodiments of the present application, the modified negative ion ore powder is the negative ion ore powder coated with the epoxy-containing resin, a dense coating layer is formed on the surface of the negative ion ore powder, and the amount of negative ion release of the negative ion ore powder is improved. Moreover, the coating of the epoxy-containing resin can also enhance the mechanical strength of the negative ion ore powder, thereby reducing the crushing or structural damage in the processing process, ensuring the stability of the negative ion release of the composite material, and improving the production yield of the composite material. In addition, by the combined action of the coating of the negative ion ore powder with the epoxy-containing resin, the compatibilizer and the degradation agent, the compatibility and dispersibility of the negative ion ore powder and the polypropylene material are improved, and the amount of negative ion release and the release stability of the composite material are also improved, thereby improving the production yield and mechanical properties of the composite material. When the composite material is applied to the inner shell of a household appliance (such as the inner shell of a refrigerator), the stable and long-acting release of negative ions is beneficial to achieve long-acting antibacterial, purification and preservation effects on the storage space inside the household appliance, thereby improving the use performance of the household appliance.

[0034] According to some embodiments of the present application, the raw material for forming the composite material includes, in terms of mass percentage: 1%-20% of the modified negative ion ore powder, 70%-95% of the polypropylene, 3%-10% of the compatibilizer, and 0.6%-1% of the degradation agent.

[0035] For example, the mass percentage of the modified negative ion ore powder can be 1%, 3%, 6%, 9%, 10%, 12%, 14%, 16%, 18%, 20%, or a range formed by any two of the above values. The mass percentage of the polypropylene can be 70%, 76%, 80%, 86%, 90%, 95%, or a range formed by any two of the above values. The mass percentage of the compatibilizer can be 3%, 5%, 10%, or a range formed by any two of the above values. The mass percentage of the degradation agent can be 0.6%, 0.8%, 1.0%, or a range formed by any two of the above values.

[0036] In this way, the mass percentages of the modified negative ion ore powder, the polypropylene, the compatibilizer, and the degradation agent in the raw material of the composite material are reasonably set, which is conducive to the reaction of the polypropylene, the modified negative ion ore powder, and the degradation agent, and conducive to the performance of the compatibilizer and the degradation agent. The compatibility of each component in the raw material of the composite material is effectively improved, the modified negative ion ore powder is not easy to agglomerate, and each component is uniformly dispersed, thereby effectively improving the long-acting property and stability of the negative ion release and improving the long-term antibacterial and purification effect of the composite material. Moreover, the modified negative ion ore powder has a heterogeneous nucleation effect, which can promote the formation of fine grains of the polypropylene, thereby improving the structural strength of the composite material, reducing the risk of cracking of the composite material during use, and prolonging the service life of the composite material product. In addition, the mechanical properties (such as bending strength, tensile strength, and impact strength) of the composite material can be ensured, the probability of stress fracture of the parts made of the composite material during use is reduced, and the use performance of the composite material is improved.

[0037] According to some embodiments of the present application, the negative ion ore powder comprises tourmaline and / or opal shale; preferably, the negative ion ore powder comprises tourmaline. And / or, the polypropylene comprises homopolymer polypropylene and / or copolymer polypropylene; preferably, the polypropylene comprises copolymer polypropylene, and the melt index is 20 g / 10 min-60 g / 10 min. And / or, the compatibilizer comprises at least one of polypropylene grafted maleic anhydride, polypropylene grafted acrylic acid, polypropylene grafted hydroxyethyl methacrylate, polypropylene grafted glycidyl methacrylate, ethylene-vinyl acetate copolymer, polyolefin elastomer, amino silane, epoxy silane, methacryloyl silane, phthalate coupling agent, and aluminate coupling agent; preferably, the compatibilizer comprises polypropylene grafted maleic anhydride. And / or, the degradation agent comprises dicumyl peroxide (DCP), sodium hydroxide, and zinc chloride, the mass ratio of sodium hydroxide to zinc chloride is (1:1)-(1:2), and the mass percentage of dicumyl peroxide in the composite material is 0.1%-0.5%; preferably, the mass ratio of sodium hydroxide to zinc chloride is 3:5.

[0038] For example, tourmaline is a mineral capable of spontaneously and permanently releasing negative ions, which can continuously ionize water molecules in the air under the effects of temperature, pressure changes or moisture, and generate negative oxygen ions through the piezoelectric effect and pyroelectric effect of the crystal itself. In addition, the negative ions and trace active ingredients (such as minerals) released by tourmaline can destroy the cell membrane structure of bacteria and mold and inhibit their reproduction, thereby achieving antibacterial effect. Moreover, tourmaline has a porous structure and water absorption, which can adjust the environmental humidity by adsorbing and releasing water. In addition, the release of negative ions by tourmaline powder does not require power consumption and is achieved only through natural physical action, and does not produce harmful by-products such as ozone, and is a natural and environmentally friendly functional material that meets the modern concept of healthy living.

[0039] Opal shale is rich in opal and clay minerals (such as montmorillonite), and its porous structure and surface active sites can ionize water molecules in the air through physical adsorption and ion exchange under changes in temperature, humidity or air flow disturbance, continuously release negative ions, and have the advantages of stable negative ion release amount and relatively high concentration, thereby being able to improve the performance of the composite material. In addition, opal shale is relatively abundant in nature, and the cost of raw material acquisition is relatively low, and the processing process does not require complex chemical treatment, which is conducive to reducing processing costs. Moreover, the negative ion release and adsorption function of opal shale relies on natural physical action, does not require power consumption, and does not produce secondary pollution such as ozone, in line with the green and environmentally friendly concept.

[0040] In the present application, the modified negative ion mineral powder is made of tourmaline and / or opal shale, which is conducive to the combination of the modified negative ion mineral powder and polypropylene, thereby being conducive to the release of negative ions while improving the compatibility of the negative ion mineral powder and polypropylene, which is conducive to the preparation and use of the composite material, and at the same time, also makes the composite material maintain excellent mechanical properties. Preferably, the negative ion mineral powder is tourmaline. Tourmaline is a mineral that can spontaneously and permanently release negative ions through piezoelectric effect and pyroelectric effect. Its crystal structure has a permanent electrode, and does not need to rely on external moisture or humidity activation. As long as there is a change in temperature (such as environmental temperature difference) or pressure (such as slight vibration), it can continuously ionize the air to generate negative ions, and the release process is more stable and less affected by environmental humidity fluctuations. Moreover, the negative ion release concentration of tourmaline is relatively high, which is conducive to improving the performance of the composite material. In addition, the structural stability of tourmaline is relatively high, which is conducive to maintaining the long-term use stability of the composite material.

[0041] Homopolymer polypropylene is polymerized from a single propylene monomer, and has excellent processing fluidity and plasticity. Moreover, the melting temperature of homopolymer polypropylene is relatively low, and it is not easy to decompose and produce harmful gases at high temperature, thereby being able to ensure that the activity of the negative ion mineral powder is not damaged by processing. In addition, the density of homopolymer polypropylene is relatively low, which is conducive to the lightweight development of the composite material and expands the application scenarios of the composite material. In addition, the raw material cost of homopolymer polypropylene is relatively low, which is conducive to reducing the production cost of the composite material.

[0042] The introduction of ethylene monomer into the copolymerized polypropylene significantly improves the toughness and impact resistance of the material, so that the copolymerized polypropylene can still maintain excellent impact resistance at low temperature. When the composite material is applied to the refrigerator freezing layer drawer, it is beneficial to improve the impact resistance of the freezing layer drawer and reduce the risk of external force cracking, thereby prolonging the service life of the refrigerator. In addition, the copolymerized polypropylene has lower melt viscosity and more stable flowability, and the shear force during processing can more effectively disperse the agglomerates of the negative ion mineral powder, thereby improving the dispersion uniformity of the negative ion mineral powder in the composite material, improving the stability of the negative ion release, and improving the performance of the composite material.

[0043] Preferably, the polypropylene is a copolymerized polypropylene. The copolymerized polypropylene can still maintain excellent impact resistance at low temperature, which is beneficial to expand the application range of the composite material (such as the refrigerator freezing layer, etc.). In addition, the ethylene-propylene copolymer segment in the copolymerized polypropylene can effectively absorb the impact capacity to avoid stress whitening; the proportion of amorphous region in the copolymer structure is relatively high, and the melt elasticity is low, which is more beneficial to the dispersion of the filler particles and reduces the risk of agglomeration; in addition, the reduction of crystallinity is beneficial to control the shrinkage and post-shrinkage of molding, and prevent the warping deformation of the product; finally, the copolymerized polypropylene has a higher thermal decomposition temperature, so that the processing temperature window is wider, which is beneficial to the molding of complex structure products.

[0044] For example, the polypropylene melt index can be 20 g / 10 min, 22 g / 10 min, 24 g / 10 min, 26 g / 10 min, 28 g / 10 min, 30 g / 10 min, 35 g / 10 min, 40 g / 10 min, 45 g / 10 min, 50 g / 10 min, 55 g / 10 min or 60 g / 10 min, or a range defined by any two of these values.

[0045] The melt index is a measure of the flowability of the polypropylene material in a molten state. When the melt index of the polypropylene material is in the range of 20 g / 10 min to 60 g / 10 min, the melt index range of the polypropylene material is reasonable. The composite material needs to mix inorganic fillers (such as negative ion mineral powder), auxiliaries (such as compatibilizers and degradants) and polypropylene material by screw extrusion, and a reasonable melt index range is beneficial to improve the dispersion uniformity of inorganic fillers, auxiliaries and polypropylene material, thereby avoiding agglomeration of negative ion mineral powder, reducing interface defects (such as bubbles, etc.), and improving the mechanical properties of the composite material. Moreover, it can also improve the aesthetics and durability of the composite material.

[0046] Polypropylene grafted maleic anhydride (PP-g-MAH) is a kind of compatibilizer which introduces polar groups of maleic anhydride into the non-polar macromolecular backbone. The anhydride groups contained in PP-g-MAH can react with the epoxy active groups in the epoxy-containing resin to form a "PP-g-MAH-epoxy" graft network, and the PP segments are interspersed in the PP resin matrix segments, so as to improve the compatibility of the matrix resin epoxy resin coated with anionic powder, which is beneficial to the improvement of material performance and the dispersion of fillers. The interpenetrating network structure can improve the mechanical strength and heat resistance of the material. In addition, the introduction of MAH destroys the regularity of the PP molecular chain, reduces the crystallinity, and thus reduces the shrinkage anisotropy, reduces the warping deformation of the product, and at the same time, it also plays a role of heterogeneous nucleation with the coated anionic powder, refines the grain, speeds up the crystallization, shortens the molding cycle, improves the efficiency, and reduces the post-shrinkage of the product caused by recrystallization.

[0047] Dicumyl peroxide is an organic peroxide which will decompose to produce free radicals at high temperature. The free radicals can abstract the hydrogen atoms on the polypropylene molecular chain, causing the PP molecular chain to break and form allyl double bonds. It can also polymerize with the epoxy active groups on the modified anionic mineral powder to form a "molecular bridge" at the interface, enhancing the compatibility of polypropylene and modified anionic mineral powder, improving the dispersion uniformity of modified anionic mineral powder, and improving the mechanical properties (such as impact strength, tensile strength, etc.) of the composite material, avoiding the problem that the addition of anionic mineral powder reduces the performance of polypropylene material and affects the use.

[0048] For example, the combination of sodium hydroxide and zinc chloride is selected as the degradation agent in the present application. Sodium hydroxide can catalyze the ring opening of epoxy-containing resins above 200°C to generate active reaction groups (such as hydroxyl and ether bond active groups), which can form a polymerization reaction with polypropylene, thereby improving the compatibility and dispersion of the modified anionic mineral powder and polypropylene. In addition, in-situ compatibilization of the modified anionic mineral powder and polypropylene is achieved, thereby improving the dispersion uniformity of the modified anionic mineral powder, avoiding agglomeration of the anionic mineral powder, reducing interface defects (such as bubbles, etc.), improving the mechanical properties and anion release stability of the composite material, and thereby improving the overall performance of the composite material. Moreover, sodium hydroxide and zinc chloride are widely available and easy to obtain, and have low use cost, which can reduce the production cost of the composite material.

[0049] For example, the mass ratio of sodium hydroxide to zinc chloride can be 1:1, 1:2, 3:5, or a range composed of two of the above values. In some specific embodiments of the present application, the mass ratio of sodium hydroxide to zinc chloride is 3:5.

[0050] When the mass ratio of sodium hydroxide to zinc chloride is in the range of (1:1) to (1:2), the mass ratio of sodium hydroxide to zinc chloride is set reasonably, which can effectively promote the polymerization reaction of the active reactive groups generated by the ring opening of epoxy resin with polypropylene, while promoting the reaction of compatibilizer with epoxy active groups. This synergistically achieves in-situ compatibilization of modified negative ion mineral powder and polypropylene, improves the dispersion uniformity of modified negative ion mineral powder, thereby improving the mechanical properties and negative ion release stability of composite materials, and thus improving the comprehensive performance of composite materials.

[0051] For example, the reaction formulas involved are as follows: The reaction formula for epoxy resin activation is shown in formula (1). Equation (1).

[0052] The reaction formula for polypropylene activation is shown in formula (2). Equation (2).

[0053] The reaction formula between activated polypropylene and activated epoxy resin is shown in formula (3). Equation (3).

[0054] The reaction formula between acid anhydride and activated epoxy resin is shown in formula (4). Equation (4).

[0055] According to some embodiments of the present invention, the raw materials forming the composite material further include, by mass percentage: 0.3%-1% antioxidant and 0.1%-1% antibacterial agent.

[0056] For example, the antioxidant may constitute 0.3%, 0.5%, 1% by mass, or a range of two of these values. In some specific embodiments of this application, the antioxidant may constitute 0.3% by mass. However, it is not limited to this.

[0057] For example, when the mass percentage of the antioxidant is in the range of 0.3%-1%, the mass percentage of the antioxidant is reasonable. The composite material needs to undergo a high-temperature and high-shear processing environment in the screw extruder, and is prone to molecular chain rupture or crosslinking due to thermal oxidation aging, resulting in deterioration of material performance. The addition of the antioxidant can effectively inhibit thermal oxidation degradation during processing, improve the production yield of the composite material, thereby reducing production cost and improving production efficiency. In addition, the addition of the antioxidant can also reduce the rupture or crosslinking of the polypropylene molecular chain during high-temperature processing, avoid the decrease of the molecular weight of the polypropylene and the change of the crystallization performance, thereby ensuring the mechanical bearing capacity. In addition, it is also beneficial to delay the aging of the composite material during processing and storage, thereby prolonging the service life of the composite material product. For example, when the composite material is used to manufacture household electrical products (such as refrigerators, etc.), the composite material has excellent mechanical properties and is not prone to oxidation, thereby ensuring the structural integrity and aesthetics of the household electrical products during long-term use, and prolonging the service life. At the same time, reasonable setting of the addition amount of the antioxidant is also beneficial to optimizing the performance of the composite material, controlling the production cost, and avoiding resource waste.

[0058] For example, the mass percentage of the antibacterial agent can be 0.1%, 0.3%, 0.5%, 1%, or a range formed by two of the above values. In some specific embodiments of the present application, the mass percentage of the antibacterial agent can be 0.2%. However, it is not limited thereto.

[0059] When the mass percentage of the antibacterial agent is in the range of 0.1%-1%, the mass percentage of the antibacterial agent is reasonable, thereby ensuring the long-term antibacterial effect of the composite material product (such as the inner shell of household electrical products, bathroom accessories, automotive interiors, etc.), so that the composite material has long-term antibacterial property. In addition, the addition amount of the antibacterial agent also affects the processing performance of the composite material. Specifically, when the mass percentage of the antibacterial agent is less than 0.1%, the mass percentage of the antibacterial agent is too low, and it is difficult to ensure the antibacterial effect and long-term antibacterial performance of the composite material product, thereby reducing the use performance of the composite material. Therefore, reasonable addition amount of the antibacterial agent can reduce the processing difficulty of the composite material, improve the production yield. Moreover, it can produce a good synergistic effect with other additives in the composite material, thereby improving the use performance of the composite material and ensuring the stability of the use performance of the composite material. In addition, the production cost can be controlled under the premise of ensuring the use performance of the composite material.

[0060] According to some embodiments of the present application, the antioxidant includes at least one of a phenolic antioxidant, a phosphite antioxidant, and a hindered amine antioxidant. And / or, the antibacterial agent includes at least one of a silver-based antibacterial agent, a zinc-based antibacterial agent, and a chitosan-based antibacterial agent. Preferably, the antibacterial agent includes a silver-loaded zirconium phosphate antibacterial agent.

[0061] For example, the phenolic antioxidant is an antioxidant that can delay the oxidative degradation of the polypropylene by providing a free hydrogen atom to capture free radicals (such as alkyl radicals, peroxide radicals, etc.) generated in the oxidation process of the material, thereby terminating the free radical chain reaction. When the phenolic antioxidant is selected as the antioxidant in the raw material of the composite material, the cracking and pulverization of the composite material product caused by aging can be effectively reduced, and the service life can be prolonged. Moreover, the addition of the phenolic antioxidant can also ensure the surface integrity of the composite material, ensure the stability of the anion release, and improve the stability of the antibacterial, purification and other properties of the composite material. In addition, the production cost of the phenolic antioxidant raw material is relatively low, which is conducive to reducing the production cost of the composite material.

[0062] The phosphite antioxidant is a peroxide decomposer that can decompose the hydroperoxide generated in the thermal oxidation process of the polypropylene into harmless alcohol or ketone compounds, thereby blocking the oxidation chain reaction, significantly reducing the thermal degradation in the processing process, maintaining the stability of the polypropylene melt flow, avoiding uneven dispersion of the modified anion mineral powder caused by material degradation, ensuring the stability of the anion release, and improving the stability of the antibacterial, purification and other properties of the composite material. At the same time, the phosphite antioxidant can act as an auxiliary antioxidant, which can effectively solve the problems of thermal oxidation, color change and functional stability of the composite material in the processing and use process by synergistic effect with the main antioxidant (such as phenolic antioxidant, etc.), thereby improving the production yield and use performance stability of the composite material. In addition, the phosphite antioxidant has high chemical stability and is not easy to migrate or volatilize, and the decomposition product is a low-toxicity or non-toxic alcohol compound without odor, which is suitable for application in safety-sensitive fields.

[0063] The hindered amine antioxidant is a high-efficiency weather-resistant antioxidant that can capture free radicals generated by photo-oxidation to decompose peroxide and form a "cyclic antioxidant system", thereby greatly improving the resistance of the composite material to ultraviolet light and long-term light, effectively delaying the aging speed of the composite material in outdoor or strong light environment, and prolonging the service life of the composite material product. In addition, the hindered amine antioxidant has long-term anti-yellowing ability. When the composite material is used in household appliances, it can help to ensure the aesthetics of the household appliances during long-term use, thereby improving the user experience. In addition, the hindered amine antioxidant has good compatibility with the anion mineral powder, thereby improving the dispersion uniformity of the modified anion mineral powder and ensuring the stability of the anion release.

[0064] It should be noted that the antioxidant can be at least one of the above-mentioned antioxidants, or a plurality of antioxidants, which can be set according to the actual reaction process. For example, the antioxidant can be a phenolic antioxidant, or a phosphite antioxidant, or a hindered amine antioxidant, or a combination of a phenolic antioxidant and a phosphite antioxidant, or a combination of a phenolic antioxidant and a hindered amine antioxidant, or a combination of a phosphite antioxidant and a hindered amine antioxidant, or a combination of a phenolic antioxidant, a phosphite antioxidant and a hindered amine antioxidant.

[0065] Silver-based antibacterial agent has broad-spectrum and long-acting bacteriostatic performance, and has good inhibitory effect on various bacteria and molds. For example, the silver-based antibacterial agent can be selected as zirconium phosphate silver antibacterial agent. For example, when the composite material is applied to the inner shell of a refrigerator, the addition of the silver-based antibacterial agent has a high inhibitory effect on common pathogenic bacteria such as Escherichia coli, Staphylococcus aureus, molds and fungi, which is beneficial to improve the safety of users. Moreover, the modified negative ion mineral powder can release negative ions in the space, without direct contact with bacteria or the surface of objects, so as to achieve the inhibitory, killing or purifying effect on microorganisms in the environment. Therefore, the silver-based antibacterial agent and the modified negative ion mineral powder can have a synergistic bacteriostatic effect, improve the bacteriostatic rate of the composite material, and further improve the safety of users.

[0066] Zinc-based antibacterial agent has the advantages of low toxicity and biocompatibility, and has a mild bacteriostatic effect. Zinc is an essential trace element for the human body, and the dissolution amount of zinc-based antibacterial agent (such as zinc oxide nanoparticles) is controllable, which will not cause irritation to human cells or skin, and is beneficial to improve the safety of users. In addition, the zinc-based antibacterial agent has excellent chemical compatibility with polypropylene and negative ion mineral powder, which can reduce the performance loss of the composite material during processing and use, and ensure the long-term use performance stability of the composite material. In addition, the raw material cost of the zinc-based antibacterial agent is relatively low, which is beneficial to control the production cost of the composite material and improve the market competitiveness. For example, the zinc-based antibacterial agent can be selected as nano-zinc oxide.

[0067] Quaternary ammonium salt antibacterial agent plays a role by destroying bacterial cell membranes and inhibiting protein synthesis, has a fast bacteriostatic speed and a wide coverage, can form a functional complementation with the "long-acting environment optimization" of negative ion release, and improve the bacteriostatic effect of the composite material. In addition, quaternary ammonium salt has low toxicity and no skin irritation, which is beneficial to expand the application prospect of the composite material in the field of household electrical products. In addition, the cost of quaternary ammonium salt antibacterial agent is relatively low, which is beneficial to control the production cost of the composite material and improve the market competitiveness.

[0068] Chitosan antibacterial agent is a natural antibacterial agent, which has good biological safety and environmental friendliness, will not cause irritation to human cells or skin, and is beneficial to improve the safety of users. In addition, the polar groups of chitosan molecules can form hydrogen bonds or electrostatic interactions with the polar modified negative ion mineral powder, improve the dispersibility of the modified negative ion mineral powder in polypropylene, reduce the decrease of mechanical properties of the material caused by the agglomeration of the modified negative ion mineral powder, and improve the mechanical properties of the composite material. Moreover, it is also beneficial to improve the stability and uniformity of negative ion release, and improve the bacteriostatic and purifying effect of the composite material.

[0069] It should be noted that the antibacterial agent can be at least one of the above antibacterial agents, or can be multiple, which can be set according to the actual reaction process. For example, the antibacterial agent can be a silver-based antibacterial agent, or a zinc-based antibacterial agent, or a quaternary ammonium salt antibacterial agent, or a chitosan-based antibacterial agent, or a combination of silver-based antibacterial agents and zinc-based antibacterial agents, or a combination of silver-based antibacterial agents and quaternary ammonium salt antibacterial agents, or a combination of silver-based antibacterial agents and chitosan-based antibacterial agents, or a combination of silver-based antibacterial agents, chitosan-based antibacterial agents and quaternary ammonium salt antibacterial agents, or a combination of silver-based antibacterial agents, chitosan-based antibacterial agents, quaternary ammonium salt antibacterial agents and chitosan-based antibacterial agents.

[0070] Preferably, the antibacterial agent is selected from a silver phosphate zirconium antibacterial agent. The silver phosphate zirconium antibacterial agent has high antibacterial properties of silver ions and controlled release ability of the zirconium phosphate carrier, so that the composite material has persistent and reliable antibacterial effect, thereby improving the stability and long-acting of the antibacterial performance of the composite material. In addition, the silver phosphate zirconium antibacterial agent can form a synergistic antibacterial effect with negative ions, thereby achieving efficient and all-round antibacterial effect. Specifically, the negative ions adsorb airborne planktonic bacteria, viruses and particulate matter by charge, thereby reducing their diffusion in the environment. The silver phosphate zirconium then efficiently inactivates the microorganisms on the surface and contact area of the composite material (such as the hands touching and the microorganisms left by the placement of objects), thereby forming a closed loop protection of “adsorption-interception-killing”, effectively improving the safety of the user and expanding the application prospect of the composite material in the field of household appliances.

[0071] According to some embodiments of the present application, the phenolic antioxidant includes antioxidant 1010.

[0072] For example, the antioxidant 1010 combines with the free radicals generated by the oxidation of polypropylene by providing hydrogen atoms, thereby avoiding the influence of free radicals on the molecular chain and ensuring the original mechanical properties (such as tensile strength and impact toughness) of the polypropylene material. This ensures that the composite material does not easily lose structural integrity due to aging and damage during long-term use (such as household appliance inner shells), thereby prolonging the service life. Moreover, the antioxidant 1010 has excellent thermal stability and excellent high-temperature processing stability, which is suitable for the processing process of the composite material. In addition, the antioxidant 1010 has good compatibility with the antibacterial agent and the negative ion mineral powder, and the parts prepared from the composite material have good mechanical properties. The antioxidant 1010 is easy to obtain, has low cost and wide applicability. Of course, the antioxidant can also be selected from antioxidant 2246, antioxidant 330, antioxidant 1076, etc.

[0073] According to some embodiments of the present application, the phosphite antioxidant includes antioxidant 168.

[0074] For example, the antioxidant 168 has excellent high-temperature stability, can quickly decompose peroxide in molten polypropylene at the processing stage, reduce the molecular weight and mechanical properties caused by processing, ensure the structural uniformity of the composite material after molding, and improve the dispersion uniformity of the modified negative ion mineral powder, thereby improving the stability and uniformity of the negative ion release, improving the antibacterial and purification effects of the composite material, and improving the use performance of the composite material. In addition, the antioxidant 168 can be used as an auxiliary antioxidant to synergistically inhibit the thermal oxidation of polypropylene with the main antioxidant (such as antioxidant 1010, etc.), so as to improve the weather resistance (such as ultraviolet resistance and high and low temperature resistance) of the material and prolong the service life of the composite material product.

[0075] The preparation method of the composite material according to the second aspect of the present application comprises the following steps: The negative ion mineral powder and the epoxy resin solution are mixed, a curing agent is added, and after defoaming treatment under vacuum conditions, stepwise curing treatment is performed to obtain a modified negative ion mineral powder; The modified negative ion mineral powder, polypropylene, a compatibilizer and a degrading agent are mixed to obtain a first mixture; The first mixture is melt-extruded in a screw extruder to obtain a composite material.

[0076] For example, the negative ion mineral powder and the pre-prepared epoxy resin solution are mixed after being weighed according to the specified amount, and then a curing agent is added to the mixture for defoaming treatment and curing treatment. In this process, the mixed solution to which the curing agent is added is subjected to defoaming treatment under vacuum conditions, which can eliminate the bubbles mixed in the system or the dissolved gas by reducing the environmental pressure, thereby eliminating the surface defects of the modified negative ion mineral powder, improving the internal density, and optimizing the performance of the composite material. In addition, the solution is further subjected to stepwise curing treatment, which can improve the uniformity of the epoxy-based resin coating on the surface of the negative ion mineral powder, ensure the uniformity and stability of the negative ion release, and improve the use performance of the composite material. Moreover, it can also avoid the crystal structure phase change (such as dehydration and lattice distortion) of the negative ion mineral powder under high temperature conditions or the deactivation of the surface active sites, thereby improving the release rate of the negative ions of the composite material and prolonging the use performance of the composite material.

[0077] In addition, a specified amount of modified negative ion mineral powder, polypropylene, a compatibilizer and a degrading agent are mixed to obtain a first mixture. Further, the first mixture is placed in a screw extruder for melt-extrusion, thereby obtaining a composite material. In this way, the composite material is melt-extruded from the first mixture in the screw extruder, which effectively improves the uniformity of the mixture of the components and is beneficial to improving the stability of the negative ion release of the composite material. In addition, the preparation method of the composite material is simple, which is beneficial to improving the production efficiency and reducing the production cost.

[0078] According to some embodiments of the present application, the mixing of the negative ion mineral powder and the epoxy resin solution, the addition of the curing agent, and the step-by-step curing treatment after the defoaming treatment under vacuum conditions specifically include: S1, mixing the negative ion mineral powder and the nano cerium oxide and then drying to obtain a second mixture; S2, mixing the epoxy resin and the first solvent to obtain an epoxy resin solution; S3, mixing the second mixture and the epoxy resin solution, dispersing for a first time, adding a curing agent, and then performing a step-by-step curing treatment after defoaming for a second time under a vacuum condition of <-0.1 Mpa; S4, grinding the material after the step-by-step curing treatment to obtain a modified negative ion mineral powder.

[0079] In step S1, the negative ion mineral powder and the nano cerium oxide are mixed according to a specified mass ratio, for example, the mass ratio of the negative ion mineral powder and the nano cerium oxide is 70% and 30% respectively, and then dried, for example, in a 120°C oven for 4h, so as to remove the free water and adsorbed water in the mixed system, avoid agglomeration of the mixed system, and make the negative ion mineral powder and the nano cerium oxide in the second mixture uniformly mixed, thereby ensuring the dispersibility of the second mixture in the subsequent preparation process and improving the performance of the composite material.

[0080] Specifically, the negative ion mineral powder releases negative ions through its crystal structure or surface reaction (such as reaction with water and air), while the nano cerium oxide surface Ce 3+ / Ce 4+ The valence state of the Ce - can efficiently catalyze the dissociation or redox reaction of water molecules (H2O) or oxygen (O2) in the air to generate hydroxyl radicals and superoxide anions (O2 + ), forming a "synergistic gain" with the negative ions released by the negative ion mineral powder, thereby increasing the amount of negative ions released. In addition, the nano cerium oxide has antioxidant properties and adsorption ability for harmful gases or impurities in the air, thereby effectively reducing the pollution of the negative ion mineral powder, maintaining the long-term release of active substances of the negative ion mineral powder, and prolonging the service life of the composite material.

[0081] CeO2 has photocatalytic properties and generates electron-hole pairs under the excitation of light (especially ultraviolet light). The electrons on the surface of CeO2 can reduce the adsorbed O2 to superoxide radicals, which then react with water molecules to generate negative oxygen ions. The holes (h + ) oxidize water molecules to hydroxyl radicals, promoting water electrolysis to produce more H - and OH 3+ ions. CeO2 has the property of promoting electron transfer, and CeO2 has redox properties. In the crystal, Ce 4+The dynamic transformation of the nanometer cerium oxide can be used as an electron transfer medium to provide electrons to O2 to generate negative ions in cooperation with the spontaneous polarization electrostatic field of tourmaline, thereby promoting the generation of negative ions. The nanometer cerium oxide has a high specific surface area and can adsorb more water and oxygen to provide raw materials for the generation of negative ions. The doping of the nanometer cerium oxide in the tourmaline forms a heterojunction interface, optimizes the charge distribution, and is more conducive to the generation of negative ions.

[0082] In step S2, the epoxy resin is weighed according to the specified mass ratio, mixed with the first solvent according to the volume ratio (for example, 1:1-1:0.5, preferably 1:0.8), and for example, the first solvent can be acetone to obtain a uniformly dispersed epoxy resin solution. Thus, mixing the epoxy resin with the first solvent can effectively reduce the viscosity of the epoxy resin, thereby reducing the dispersion difficulty of the epoxy resin mixed solution and the second mixture, improving the dispersion uniformity, and thereby improving the performance stability of the modified negative ion mineral powder.

[0083] In step S3, the second mixture and the epoxy resin solution are mixed, and after mixing, they are placed in an ultrasonic dispersing machine for a first time, for example, 30 min. Then, the curing agent is added to the mixed system and stirred at a speed of 500 rpm for 10 min to obtain a third mixture. For example, the mass ratios of the epoxy resin solution, the second mixture and the curing agent are 25%, 50% and 25%, respectively. Further, the above-mentioned third mixture is subjected to a second time, for example, 15 min, of vacuum degassing treatment under a vacuum condition of <-0.1 Mpa, so as to eliminate the bubbles mixed in the mixed system or the dissolved gas, thereby eliminating the surface defects of the modified negative ion mineral powder, improving the internal density, and optimizing the performance of the composite material. In addition, the above-mentioned third mixture subjected to the degassing treatment is subjected to a stepwise curing treatment, so as to make the reaction heat uniform by controlling the temperature of each stage of the curing treatment, gradually improving the crosslinking density, which is conducive to improving the interfacial bonding force between the epoxy resin and the negative ion mineral powder, thereby improving the mechanical properties of the modified negative ion mineral powder, to obtain a second material.

[0084] In step S4, the second material is subjected to a grinding treatment. For example, the blocky second material is ground in a ball mill to 500-10000 mesh to obtain a powder-like modified negative ion mineral powder. Thus, the modified negative ion mineral powder obtained by grinding effectively reduces the particle size and improves the specific surface area, so as to be able to fully contact with air, improve the negative ion release rate, and improve the use performance. In addition, the modified negative ion mineral powder prepared by the above-mentioned reaction process has uniform epoxy resin coating, uniform particle size, and large specific surface area, which can be more fully contacted with air or water, thereby improving the negative ion release concentration and reaction efficiency, and improving the use performance of the composite material. Moreover, it is also conducive to improving the dispersibility of the modified negative ion mineral powder and avoiding agglomeration, thereby facilitating the smooth progress of the subsequent process in the preparation process of the composite material.

[0085] According to some embodiments of the present application, the conditions of the stepwise curing treatment include: successively incubating at 70-90°C for 1-3 hours, at 110-130°C for 1-3 hours, and at 140-160°C for 0.5-2 hours.

[0086] For example, the first material is subjected to a stepwise curing treatment, i.e., a step-by-step treatment of “low-temperature pre-curing-middle-temperature transition-high-temperature complete curing”. Specifically, the first material is incubated at 70-90°C for 1-3 hours, i.e., a low-temperature pre-curing stage, during which the epoxy resin is slowly crosslinked, the viscosity gradually increases, the material morphology is preliminarily fixed, and the residual bubbles, solvents or low-molecular volatile components slowly escape, obtaining a low-temperature pre-cured first material. The low-temperature pre-cured first material is incubated at 110-130°C for 1-3 hours, i.e., a middle-temperature transition stage, during which the crosslinking degree of the epoxy resin gradually increases, and the molecular chains are slowly adjusted and arranged, obtaining a middle-temperature transition first material. The middle-temperature transition first material is incubated at 140-160°C for 0.5-2 hours, i.e., a high-temperature complete curing stage, during which the final crosslinking is completed on the basis of the stress being partially released, obtaining a second material.

[0087] In this way, the stepwise curing treatment controls the temperature of each stage to make the reaction heat release uniform, gradually increase the crosslinking density, and form a more regular and uniform three-dimensional network structure, which is conducive to improving the interfacial bonding force between the epoxy resin and the negative ion mineral powder, thereby improving the mechanical properties of the modified negative ion mineral powder. Preferably, the conditions of the stepwise curing treatment include: incubation at 80°C for 2 hours, incubation at 120°C for 2 hours, and incubation at 150°C for 1 hour.

[0088] According to some embodiments of the present application, the processing temperature in the screw extruder is set in sections, and the processing temperatures are 150-180°C, 190-210°C and 200-220°C in sequence. And / or, the rotation speed of the screw extruder is 250-600 rpm.

[0089] For example, the extrusion process of the first mixture in the screw extruder can be divided into three stages: a feeding section, a compression section and a homogenization section. The first mixture in the screw extruder is subjected to processing temperatures of 150-180°C, 190-210°C and 200-220°C in sequence, i.e., the extrusion temperature gradient is set, so as to meet the temperature requirements of each stage and match the melting characteristics of the materials in each stage, so that the melt viscosity is moderate, the mixing is uniform, the interface is tightly bonded, the molecular chains are fully entangled, and the shear strength of the composite material is improved. In addition, the low-temperature feeding section avoids prematurely triggering local chemical reactions when the material is not fully melted and dispersed, prevents pre-reactions from causing uneven distribution of components, the middle-temperature section allows the resin to fully melt, improving the dispersibility of the filler, and the high-temperature section provides reaction activation energy to promote the chemical reaction to fully react.

[0090] For example, the screw extruder rotates at 250 rpm-600 rpm, and the rotation speed range of the screw extruder is reasonably set to adapt to the processing temperature in the screw extruder at different stages, improve the shear strength of the extrusion process, and thus improve the mechanical strength of the composite material, reduce the crack fracture of the composite material product caused by external force during use, and prolong the service life. In addition, reverse conveying thread elements can be added in the middle and later stages (such as the compression stage and the homogenization stage) of the screw extrusion to prolong the residence time of each component and improve the depolymerization reaction effect, thereby improving the polymerization reaction efficiency of the modified negative ion mineral powder and polypropylene, improving the compatibility and dispersibility of the modified negative ion mineral powder and polypropylene material, and further improving the stability and uniformity of the negative ion release of the composite material. Then, through the steps of melt blending, extrusion drawing, cooling, air drying, granulation, drying and the like, a composite material with high strength, high dispersion and high negative ion release amount is prepared.

[0091] For example, the preparation method of the composite material according to the present application comprises the following steps: Step one: preparation of modified negative ion mineral powder a, pretreatment: (1) Mix the negative ion mineral powder and nano cerium oxide, and then dry them in an oven at 110°C-130°C for 4h-6h (preferably 120°C for 4h), completely remove the moisture, and obtain a second mixture with a moisture content of less than 0.1%.

[0092] (2) Mix the epoxy resin and the first solvent in a volume ratio of 1:1-1:0.5 at 50°C-70°C (preferably 60°C) to obtain an epoxy resin mixture.

[0093] b, preparation of modified negative ion mineral powder: Put the epoxy resin mixture and the second mixture into an ultrasonic disperser for 30min (first time), then add a curing agent and stir at a speed of 500 rpm for 10min (second time), and degas under vacuum conditions (-0.1 MPa) for 15min to obtain a first material. Pour the first material into a mold for stepwise curing. The conditions for stepwise curing include sequentially keeping at 80°C for 2h, at 120°C for 2h, and at 150°C for 1h to obtain a block-shaped modified negative ion mineral powder (second material). Grind the block-shaped modified negative ion mineral powder in a ball mill to 500-10000 mesh to obtain the modified negative ion mineral powder.

[0094] Step two: preparation of the composite material c. The modified negative ion mineral powder, polypropylene, compatibilizer, degradation agent, antioxidant and antibacterial agent are weighed according to the specified amount, mixed and put into a high-mixing pot, stirred and mixed at a speed of 300 rpm-600 rpm for 1 min-3 min to obtain a first mixture.

[0095] d. The first mixture is added to the twin-screw extruder, and the temperature gradient in the screw extruder is set. The processing temperature is 150°C-180°C, 190°C-210°C and 200°C-220°C in turn, the speed is 250 rpm-600 rpm, the screw combination is strong shear, and the reverse conveying thread element is added in the middle and rear sections. After melting blending, extrusion drawing, cooling, air drying, granulation and drying, a composite material is obtained.

[0096] Optionally, the first solvent includes acetone. In this way, acetone has excellent solubility for epoxy resin, so as to quickly disperse the epoxy resin, reduce the viscosity of the system, and ensure the uniformity of the reaction system. Moreover, dissolving the epoxy resin in acetone is conducive to reducing the viscosity of the epoxy resin, thereby reducing the dispersion difficulty of the epoxy resin mixed solution and the second mixture, improving the dispersion uniformity, and thus improving the performance stability of the modified negative ion mineral powder. In addition, the raw material price of acetone is relatively low, which is conducive to reducing the production cost of the composite material.

[0097] Optionally, the particle size of the modified negative ion mineral powder after ball milling can be 500-10000 mesh.

[0098] For example, when the particle size of the modified negative ion mineral powder after ball milling is in the range of 500-10000 mesh, the modified negative ion mineral powder is more fully contacted with air or water, thereby improving the negative ion release concentration and release efficiency, and improving the use performance of the composite material. In addition, it is also conducive to improving the dispersibility of the modified negative ion mineral powder and avoiding agglomeration, thereby improving the mechanical properties of the composite material and enhancing the strength of the composite material. Preferably, the particle size of the modified negative ion mineral powder is 5000 mesh. In this way, the particle size of the modified negative ion mineral powder is reasonably set, which further improves the negative ion release concentration and efficiency, and improves the use performance of the composite material.

[0099] Optionally, the curing agent includes polyamide 650.

[0100] The polyamide 650 is an aliphatic polyamide curing agent condensed by a dimer acid and a polyamine. The polyamide 650 contains multiple active primary amine groups and secondary amine groups in the molecule. The amine groups can undergo ring-opening reaction with the epoxy groups of the epoxy resin at room temperature, and the curing can be completed without high temperature heating, which is conducive to reducing the curing difficulty of the first material and improving the curing effect, thereby improving the uniformity of the epoxy resin outside the negative ion mineral powder, and further improving the uniformity and stability of the negative ion release of the composite material. In addition, the molecular structure of the polyamide 650 contains long-chain aliphatic groups (carbon chains from dimer acid), which play a “toughening” role in the cured epoxy resin network, reducing the internal stress generated by volume shrinkage during curing, reducing the cracking risk of the epoxy resin coated on the negative ion mineral powder, ensuring the stability of the performance of the modified negative ion mineral powder, and improving the use performance of the composite material. In addition, the curing agent can also be selected from amine curing agents, acid anhydride curing agents, and cationic curing agents. The amine curing agent can also be ethylenediamine, isophorone diamine, cyclohexanediamine, m-phenylenediamine, diaminodiphenylmethane, polyamide 651, etc.

[0101] According to the third aspect of the embodiment of the present application, the refrigerator comprises a cabinet (not shown in the figure), a cabinet door (not shown in the figure) and a drawer (not shown in the figure).

[0102] Specifically, the cabinet is formed with an opening. The cabinet door is arranged at the opening and used to open and close the opening, and the cabinet and the cabinet door jointly define a containing space. The drawer comprises the composite material according to the first aspect of the embodiment or the composite material prepared by the preparation method according to the second aspect of the embodiment. And / or, the cabinet comprises an inner shell configured as an inner wall surface of the containing space, wherein the inner shell comprises the composite material according to the first aspect of the embodiment or the composite material prepared by the preparation method according to the second aspect of the embodiment.

[0103] For example, the open-door refrigerator comprises a cabinet and a cabinet door. The cabinet door is arranged at the opening of the cabinet, thereby jointly defining a containing space with the cabinet to place the articles that need to be stored at low temperature or for a long time in daily life. The cabinet comprises an inner shell configured as an inner wall surface of the refrigerator. In addition, the refrigerator further comprises a drawer for separating the containing space into multiple independent spaces, thereby improving the space utilization of the containing space and realizing effective zoning of the articles in the refrigerator, so as to prevent the refrigerator from producing odor due to mixed storage of the articles and improve the utilization of the storage space.

[0104] The drawers and inner shell are made of composite materials. This design allows for long-lasting and stable antibacterial effects on the storage space without the need for external antibacterial agents, improving user safety. Furthermore, the composite material stably releases negative ions, regulating humidity distribution within the refrigerator's interior and improving the preservation of stored items (such as fruits and vegetables), extending their shelf life and enhancing the user experience. In addition, it can replace the negative ion modules used in traditional refrigerators, generating no ozone, thus improving the refrigerator's environmental friendliness and overall performance.

[0105] The embodiments of the present invention are described in detail below. It should be noted that the embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. In addition, unless otherwise specified, all reagents used in the following embodiments are commercially available or can be synthesized according to the methods described herein or known to others. For reaction conditions not listed, they are also readily available to those skilled in the art.

[0106] The composite materials of the present invention will be described through exemplary embodiments and comparative examples. The following describes the performance tests performed on the composite materials of the embodiments and comparative examples.

[0107] Example 1 Step 1: Preparation of modified negative ion mineral powder a. Preprocessing: (1) Mix 70% by mass of negative ion mineral powder (nano tourmaline powder) and 30% by mass of nano cerium oxide and dry in an oven at 120°C for 4 hours to completely remove moisture. The moisture content is less than 0.1%, and a second mixture is obtained.

[0108] (2) Epoxy resin and acetone (first solvent) are mixed at a volume ratio of 1:0.8 to obtain epoxy resin mixture.

[0109] b. Preparation of modified negative ion mineral powder: (1) The mixture liquid with a mass percentage of 25% of epoxy resin and the second mixture with a mass percentage of 50% are placed in an ultrasonic dispersing machine for dispersion for 30 min (first time), then a curing agent with a mass percentage of 25% is added for stirring at a speed of 500 rpm for 10 min (second time), and is degassed under vacuum condition (-0.1 MPa) for 15 min to obtain a first material, and then the first material is poured into a mold for stepwise curing. The stepwise curing treatment conditions include sequentially keeping at 80℃ for 2 h, 120℃ for 2 h, and 150℃ for 1 h to obtain a blocky modified negative ion ore powder (second material). The blocky modified negative ion ore powder is ground in a ball mill to 500-10000 mesh to obtain the modified negative ion ore powder.

[0110] Step two: preparation of the composite material c. 1% of the modified negative ion ore powder, 94.6% of the polypropylene, 3% of the polypropylene grafted maleic anhydride, 0.1% of the dicumyl peroxide, 0.5% of the zinc chloride, 0.3% of the sodium hydroxide, 0.1% of the antioxidant 1010, 0.2% of the antioxidant 168, and 0.2% of the antibacterial agent (zirconium phosphate silver antibacterial agent) are weighed according to the mass percentage, mixed, and put into a high-mix pot, and stirred and mixed at a speed of 300-600 rpm for 1-3 min to obtain a first mixture.

[0111] d. The first mixture is added to a twin-screw extruder, and a temperature gradient in the screw extruder is set. The temperature is 150℃-180℃, 190℃-210℃, and 200℃-220℃ in sequence, the speed is 250-600 rpm, and a reverse conveying thread element is added in the middle and rear sections, and the composite material is obtained through melt blending, extrusion drawing, cooling, air drying, granulation, and drying.

[0112] Examples 2-8 The preparation method of Examples 2-8 is basically the same as that of Example 1, except that the addition amount of each component of Examples 2-8 is different, which is shown in Table 1.

[0113] Comparative Examples 1-3 The preparation method of Comparative Example 1 is basically the same as that of Example 1, except that no modified negative ion ore powder is added in Comparative Example 1, and 7% of uncoated negative ion ore powder is added, and the content of the negative ion ore powder is equivalent to the content of the negative ion ore powder in the modified negative ion ore powder in Example 2. The parameter limits are shown in Table 1.

[0114] Table 1: Setting of related parameters in Examples 1-8 and Comparative Examples 1-3

[0115] Performance test: 1. Tensile strength test: the test standard refers to GB / T 1040.2.

[0116] 2. Bending strength test: the test standard refers to GB / T 9341.

[0117] 3. Bending modulus test: the test standard refers to GB / T 9341.

[0118] 4. Impact strength test: the test standard refers to GB / T 1843.

[0119] 5. Chlorophyll content retention rate test after 7 days of storage: 6. Negative ion release amount test: the test equipment is COM-3010 Prox.

[0120] Table 2 Performance test results of Examples 1-8 and Comparative Examples 1-3

[0121] As can be seen from Table 2, the comprehensive performance of Examples 2 and 3 is better, which improves the compatibility and the negative ion release amount, and at the same time, can achieve a better balance of rigidity and toughness, and is more conducive to the use of the composite material. For Examples 7 and 8, the modified negative ion mineral powder content in Example 7 is higher, which can increase the rigidity of the composite material, that is, the tensile strength and bending performance are higher, but the degradation agent content is lower than the limited value of the present application, and the compatibility is poorer than the normal degradation agent content, and the impact strength is lower. The modified negative ion mineral powder content in Example 8 is lower, and the performance is poorer than Example 1 compared with Example 1. It is also confirmed that the comprehensive performance of the composite material prepared by using the components and contents defined in the present application is better.

[0122] The negative ion mineral powder content in Comparative Example 1 is equivalent to the content of the negative ion mineral powder in the modified negative ion mineral powder in Example 2. Comparative Example 1 has poorer compatibility compared with Example 2, so the impact strength is very small. The comprehensive performance of Comparative Example 1 is significantly poorer than the comprehensive performance of Examples 1-9. Comparative Example 2 has a large difference in overall performance compared with Example 2, only adding a degradation agent. The performance of Comparative Example 3 is poorer than that of Comparative Example 2.

[0123] The composite material and the preparation method thereof, the refrigerator and the operation according to the embodiments of the present application are known to those skilled in the art, and will not be described in detail here.

[0124] In the description of the specification, reference to "one embodiment", "some embodiments", "an exemplary embodiment", "an example", "a specific example", or "some examples" means that a particular feature, structure, material, or characteristic being described is included in at least one embodiment or example of the application. The appearances of the phrases "in one embodiment", "in some embodiments", "in an exemplary embodiment", "an example", "a specific example", or "some examples" in various places in the specification are not necessarily referring to the same embodiment or example.

[0125] While embodiments of the application have been shown and described, it is to be understood that the application is not limited to these embodiments. Rather, it is the intention that modifications, changes, substitutions, and variations be made to the embodiments in keeping with the principles and spirit of the application. The scope of the application is to be limited only by the claims and their equivalents.

Claims

1. A composite material, characterized in that, The raw materials for forming the composite material include: modified negative ion mineral powder, polypropylene, compatibilizer, and degradation agent; The modified negative ion mineral powder includes negative ion mineral powder and epoxy-containing resin coated on the negative ion mineral powder.

2. The composite material according to claim 1, characterized in that, The raw materials forming the composite material, by weight percentage, include: 1%-20% modified negative ion mineral powder, 70%-95% polypropylene, 3%-10% compatibilizer and 0.6%-1% degradation agent.

3. The composite material according to claim 1, characterized in that, The negative ion mineral powder includes tourmaline and / or opal shale; preferably, the negative ion mineral powder includes tourmaline; and / or The polypropylene includes homopolymer polypropylene and / or copolymer polypropylene; preferably, the polypropylene includes copolymer polypropylene with a melt index of 20 g / 10 min to 60 g / 10 min; and / or The compatibilizer comprises at least one selected from polypropylene grafted with maleic anhydride, polypropylene grafted with acrylic acid, polypropylene grafted with hydroxyethyl methacrylate, polypropylene grafted with glycidyl methacrylate, ethylene-vinyl acetate copolymer, polyolefin elastomer, aminosilane, epoxysilane, methacryloxysilane, phthalate coupling agent, and aluminate coupling agent; preferably, the compatibilizer comprises polypropylene grafted with maleic anhydride; and / or The degradation agent includes dicumyl peroxide, sodium hydroxide, and zinc chloride, wherein the mass ratio of sodium hydroxide to zinc chloride is (1:1) to (1:2), and the mass percentage of dicumyl peroxide in the composite material is 0.1% to 0.5%; preferably, the mass ratio of sodium hydroxide to zinc chloride is 3:

5.

4. The composite material according to claim 2 or 3, characterized in that, The raw materials forming the composite material, by weight percentage, also include: 0.3%-1% antioxidant and 0.1%-1% antibacterial agent.

5. The composite material according to claim 4, characterized in that, The antioxidant includes at least one of phenolic antioxidants, phosphite antioxidants, and hindered amine antioxidants; and / or The antibacterial agent includes at least one of silver-based antibacterial agents, zinc-based antibacterial agents, quaternary ammonium salt antibacterial agents, and chitosan-based antibacterial agents; preferably, the antibacterial agent includes a silver-loaded zirconium phosphate antibacterial agent.

6. The method for preparing the composite material according to any one of claims 1-5, characterized in that, Includes the following steps: The negative ion mineral powder and epoxy-containing resin solution are mixed, a curing agent is added, and after degassing under vacuum conditions, a step-by-step curing process is carried out to obtain modified negative ion mineral powder. The modified negative ion mineral powder, polypropylene, compatibilizer, and degrading agent in the specified amounts are mixed to obtain a first mixture; The first mixture is melt-extruded in a screw extruder to obtain the composite material.

7. The method for preparing the composite material according to claim 6, characterized in that, The process of mixing negative ion mineral powder and epoxy-containing resin solution, adding a curing agent, and then performing a step-by-step curing process after degassing under vacuum conditions specifically includes: The negative ion mineral powder and nano-cerium oxide are mixed and then dried to obtain a second mixture; The epoxy resin and the first solvent are mixed to obtain the epoxy-containing resin solution; After mixing the second mixture and the epoxy-containing resin solution and dispersing for a first time, the curing agent is added, and after degassing under vacuum conditions of <-0.1 MPa for a second time, a step-curing process is performed. The material after the stepped curing treatment is ground to obtain the modified negative ion mineral powder.

8. The method for preparing the composite material according to claim 7, characterized in that, The conditions for the stepped curing process include: The temperature was kept at 70℃-90℃ for 1h-3h, at 110℃-130℃ for 1h-3h, and at 140℃-160℃ for 0.5h-2h.

9. The method for preparing the composite material according to any one of claims 6-8, characterized in that, The processing temperature inside the screw extruder is set in stages, with the processing temperatures sequentially set to 150℃-180℃, 190℃-210℃, and 200℃-220℃; and / or The screw extruder operates at a speed of 250 rpm to 600 rpm.

10. A refrigerator, comprising: Cabinet body, wherein the cabinet body has an opening; A cabinet door is provided at the opening for opening and closing the opening; the cabinet body and the cabinet door together define the accommodating space. The refrigerator is characterized in that it further includes: Drawer, the drawer comprising the composite material according to any one of claims 1-5, or the composite material prepared by the method according to any one of claims 6-9; and / or The cabinet includes an inner shell, which is configured as the inner wall surface of the accommodating space. The inner shell comprises a composite material according to any one of claims 1-5, or a composite material prepared by any one of claims 6-9.

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