Core-shell nano calcium carbonate filler, silicone sealant and preparation methods of core-shell nano calcium carbonate filler and silicone sealant

Abstract

The invention provides a core-shell nano calcium carbonate filler, a silicone sealant and a preparation method thereof, and the core-shell nano calcium carbonate comprises a calcium carbonate core layer, a silane coupling agent middle shell layer and a chitosan oligosaccharide outer shell layer; the silane coupling agent middle shell layer is wrapped outside the calcium carbonate core layer; the chitosan oligosaccharide outer shell layer is wrapped outside the silane coupling agent middle shell layer. The silicone sealant prepared by the method is high in stability and excellent in antibacterial ability.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of silicone sealants, and specifically relates to a core-shell nano calcium carbonate filler, silicone sealant and a preparation method thereof. Background Art

[0002] Antibacterial room temperature vulcanized silicone rubber is widely used for waterproof sealing in home interiors, bathrooms, toilets, etc. due to its excellent comprehensive performance. Good antibacterial effect can be achieved by adding an appropriate amount of antibacterial agent to the formula system.

[0003] A Chinese patent document with publication number CN118851793A discloses an antibacterial ceramic filter material, a preparation method and application thereof, and a filter element. The invention mixes an inorganic antibacterial agent with other components to form an antibacterial ceramic filter material. The inorganic antibacterial agent can be evenly dispersed in the ceramic filter material. Compared with antibacterial agent coating, adsorption penetration, and grafting, the ceramic filter material of the invention has a longer antibacterial timeliness and can solve the problem of short antibacterial timeliness in the prior art. A Chinese patent document with publication number CN118580599A discloses an anti-fog and anti-mildew rare earth antibacterial protective film and a preparation method thereof. The invention utilizes the antibacterial effect of a special rare earth inorganic antibacterial material to prepare a fresh-keeping film with good antibacterial and antibacterial effects, which can inhibit the growth and reproduction of microorganisms from many aspects and prolong the storage time of fresh food. The method has a simple preparation process, is easy to use, is non-toxic and harmless to the human body, and is suitable for large-scale industrial production. As the quality of human living environment continues to improve, people's health awareness continues to increase. Traditional inorganic antibacterial agents have poor stability and certain toxicity.

[0004] Therefore, it is very necessary to develop an antibacterial RTV with strong stability, long duration and good biocompatibility. Summary of the invention

[0005] The technical problem solved by the present invention is to provide a core-shell nano calcium carbonate filler, a silicone sealant and a preparation method thereof, aiming to solve the problems of poor stability, short duration and certain toxicity when traditional antibacterial agents are added to deketoxime type silicone sealants.

[0006] In order to solve the above problems, the first aspect of the present invention provides a core-shell nano calcium carbonate filler, comprising:

[0007] A calcium carbonate core layer, a silane coupling agent intermediate shell layer and a chitosan oligosaccharide outer shell layer; the silane coupling agent intermediate shell layer is wrapped outside the calcium carbonate core layer; and the chitosan oligosaccharide outer shell layer is wrapped outside the silane coupling agent intermediate shell layer.

[0008] Preferably, the intermediate shell layer of the silane coupling agent is wrapped around the calcium carbonate core layer by chemical adsorption; the intermediate shell layer of the silane coupling agent is connected to the outer shell layer of the chitosan oligosaccharide by chemical bonds.

[0009] Preferably, the particle size of the calcium carbonate core layer is 60-80 nm, and the thickness of the chitosan oligosaccharide outer shell layer is 20-22 nm.

[0010] Preferably, the silane coupling agent is silane coupling agent KH-560.

[0011] The second aspect of the present invention provides a method for preparing the core-shell nano calcium carbonate as described above, comprising:

[0012] Calcium carbonate is prepared into a calcium carbonate suspension, and a silane coupling agent is added to react to obtain calcium carbonate modified by the silane coupling agent; then chitosan oligosaccharide is added to the calcium carbonate modified by the silane coupling agent to react to obtain a product, and the product is separated to obtain the core-shell nano calcium carbonate.

[0013] Preferably, when the silane coupling agent is added for reaction, the mass of the silane coupling agent is 0.5% to 2% of the calcium carbonate; the reaction temperature is 70 to 90° C., and the reaction time is 6 to 8 hours; when chitosan oligosaccharide is added to the calcium carbonate modified with the silane coupling agent for reaction, the molar ratio of the calcium carbonate modified with the silane coupling agent to the chitosan oligosaccharide is controlled to be 1:2 to 10, the reaction temperature is 110 to 120° C., and the reaction time is 8 to 10 hours.

[0014] The third aspect of the present invention provides a silicone sealant comprising the following components in parts by weight:

[0015] 100 parts of α,ω-dihydroxypolydimethylsiloxane, 80-140 parts of core-shell nano calcium carbonate filler, 2-10 parts of plasticizer, 8-20 parts of cross-linking agent, 0.5-3 parts of coupling agent, 0.2-0.8 parts of polymer antibacterial agent, and 0.01-1.5 parts of catalyst.

[0016] Preferably, the viscosity of the α,ω-dihydroxy polydimethylsiloxane at 25° C. is 20,000 to 100,000 mPa.s;

[0017] The plasticizer is dimethyl silicone oil, and the viscosity of the dimethyl silicone oil at 25° C. is 100 to 10000 mpa.s;

[0018] The crosslinking agent is one or a mixture of methyl tributylacetoximosilane, vinyl tributylacetoximosilane, methyl tris(methyl isobutyl ketoxime) silane, and vinyl tris(methyl isobutyl ketoxime) silane;

[0019] The coupling agent is one or a mixture of γ-aminopropyltrimethoxysilane, γ-glycidyloxypropyltrimethoxysilane, γ-(2,3-epoxypropyl)propyltriethoxysilane, and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane;

[0020] The polymer antibacterial agent is one or a mixture of polyhexamethyleneguanidine hydrochloride, dodecyldimethylbenzyl ammonium chloride, n-butyl-1,2-benzisothiazolin-3-one (BBIT);

[0021] The catalyst is one or a mixture of di-n-butyltin dilaurate, di-n-butyltin diacetate and stannous octoate.

[0022] A fourth aspect of the present invention provides a method for preparing the silicone sealant as described above, comprising the following steps:

[0023] S1: mixing α,ω-dihydroxy polydimethylsiloxane, core-shell nano calcium carbonate filler and plasticizer to obtain a semi-finished product;

[0024] S2: adding a cross-linking agent, a coupling agent, a polymer antibacterial agent and a catalyst to the semi-finished product, stirring, and obtaining the silicone sealant.

[0025] Preferably, step S1 specifically comprises the following steps: adding α,ω-dihydroxy polydimethylsiloxane, core-shell nano calcium carbonate filler and plasticizer into a kneader for mixing, heating to 120-140° C., evacuating to above -0.095 MPa for 2-3 hours to obtain a semi-finished product, and cooling to room temperature;

[0026] Step S2 specifically includes the following steps: adding a crosslinking agent, a coupling agent, a polymer antibacterial agent and a catalyst to the semi-finished product, stirring for 20 to 40 minutes under a vacuum degree of -0.095 MPa or above, and then storing the discharged product in a sealing cylinder to obtain the silicone sealant.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] like Figure 1 As shown, the present invention first modifies nano calcium carbonate with silane coupling agent KH-560 to make the surface of nano calcium carbonate have epoxy groups. The generated nano calcium carbonate with epoxy groups on the outer surface reacts with chitosan oligosaccharide to generate a core-shell nano filler with antibacterial properties. And α,ω-dihydroxy polydimethylsiloxane, plasticizer, crosslinking agent, coupling agent, polymer antibacterial agent and catalyst are used as raw materials, and the core-shell nano filler is added to a single-component room temperature vulcanized silicone rubber.

[0029] The natural high molecular weight antibacterial agent polymer chitosan oligosaccharide is grafted onto the surface of inorganic nano-calcium carbonate to form a polymer / inorganic core-shell nanoparticle material, which not only ensures the reinforcing performance of inorganic nano-calcium carbonate on RTV, but also provides its antibacterial properties against microorganisms. At the same time, synthetic high molecular weight antibacterial agents are added to the sealant and used in combination with chitosan oligosaccharide nano-calcium carbonate, the antibacterial property reaches an effect of 1+1>2.

[0030] Chitosan oligosaccharides are the products of chitosan depolymerization. Polyhexamethyleneguanidine hydrochloride, dodecyldimethylbenzyl ammonium chloride and n-butyl-1,2-benzisothiazolin-3-one (BBIT) all have the characteristics of low addition amount, high efficiency, stability and long-term effect. They have no bioaccumulation after use and will not cause continuous pollution to the environment. They are green, natural and environmentally friendly polymer substances. They are introduced into room temperature vulcanized silicone rubber to finally prepare a green, environmentally friendly and biocompatible antibacterial RTV material. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a structural schematic diagram of the synthesis process of the core-shell nano calcium carbonate filler described in an embodiment of the present invention. DETAILED DESCRIPTION

[0032] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solution of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] A first aspect of an embodiment of the present invention provides a core-shell nano calcium carbonate filler, comprising:

[0034] A calcium carbonate core layer, a silane coupling agent intermediate shell layer and a chitosan oligosaccharide outer shell layer; the silane coupling agent intermediate shell layer is wrapped outside the calcium carbonate core layer; and the chitosan oligosaccharide outer shell layer is wrapped outside the silane coupling agent intermediate shell layer.

[0035] The core-shell nano calcium carbonate filler of the embodiment of the present invention is first modified with silane coupling agent KH-560 to make the surface of the nano calcium carbonate have epoxy groups. The produced nano calcium carbonate with epoxy groups on the outer surface is then reacted with chitosan oligosaccharide to generate a core-shell nano filler with antibacterial properties.

[0036] In some embodiments, the intermediate shell layer of the silane coupling agent is wrapped around the calcium carbonate core layer by chemical adsorption; the intermediate shell layer of the silane coupling agent is connected to the outer shell layer of the chitosan oligosaccharide by chemical bonds.

[0037] In some embodiments, the particle size of the calcium carbonate core layer is 60-80 nm, and the thickness of the chitosan oligosaccharide outer shell layer is 20-22 nm.

[0038] In some embodiments, the silane coupling agent is silane coupling agent KH-560.

[0039] A second aspect of the embodiment of the present invention provides a method for preparing the core-shell nano calcium carbonate as described above, comprising:

[0040] Calcium carbonate is prepared into a calcium carbonate suspension, and a silane coupling agent is added to react to obtain calcium carbonate modified by the silane coupling agent; then chitosan oligosaccharide is added to the calcium carbonate modified by the silane coupling agent to react to obtain a product, and the product is separated to obtain the core-shell nano calcium carbonate.

[0041] In some embodiments, when the silane coupling agent is added for reaction, the mass of the silane coupling agent is 0.5% to 2% of the calcium carbonate; the reaction temperature is 70 to 90°C, and the reaction time is 6 to 8 hours; when chitosan oligosaccharide is added to the calcium carbonate modified with the silane coupling agent for reaction, the molar ratio of the calcium carbonate modified with the silane coupling agent to the chitosan oligosaccharide is controlled to be 1:2 to 10, the reaction temperature is 110 to 120°C, and the reaction time is 8 to 10 hours.

[0042] A third aspect of an embodiment of the present invention provides a silicone sealant comprising the following components in parts by weight:

[0043] 100 parts of α,ω-dihydroxypolydimethylsiloxane, 80-140 parts of core-shell nano calcium carbonate filler, 2-10 parts of plasticizer, 8-20 parts of cross-linking agent, 0.5-3 parts of coupling agent, 0.2-0.8 parts of polymer antibacterial agent, and 0.01-1.5 parts of catalyst.

[0044] Preferably, the silicone sealant comprises the following components in parts by weight:

[0045] 100 parts of α,ω-dihydroxypolydimethylsiloxane, 110-140 parts of core-shell nano calcium carbonate filler, 5 parts of plasticizer, 12 parts of cross-linking agent, 1 part of coupling agent, 0.4-0.8 parts of polymer antibacterial agent, and 0.2 parts of catalyst.

[0046] In some embodiments, the viscosity of the α,ω-dihydroxy polydimethylsiloxane at 25° C. is 20,000 to 100,000 mPa.s;

[0047] The plasticizer is dimethyl silicone oil, and the viscosity of the dimethyl silicone oil at 25° C. is 100 to 10000 mpa.s;

[0048] The crosslinking agent is one or a mixture of methyl tributylacetoximosilane (CAS registration number is 22984-54-9), vinyl tributylacetoximosilane (CAS registration number is 2224-33-1), methyl tris(methyl isobutyl ketoxime) silane (CAS registration number is 37859-57-7), and vinyl tris(methyl isobutyl ketoxime) silane (CAS registration number is 156145-64-1);

[0049] The coupling agent is one or a mixture of γ-aminopropyltrimethoxysilane, γ-glycidyloxypropyltrimethoxysilane, γ-(2,3-epoxypropyl)propyltriethoxysilane, and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane;

[0050] The polymer antibacterial agent is one or a mixture of polyhexamethyleneguanidine hydrochloride, dodecyldimethylbenzyl ammonium chloride, n-butyl-1,2-benzisothiazolin-3-one (BBIT);

[0051] The catalyst is one or a mixture of di-n-butyltin dilaurate, di-n-butyltin diacetate and stannous octoate.

[0052] A fourth aspect of the embodiments of the present invention provides a method for preparing the silicone sealant as described above, comprising the following steps:

[0053] S1: mixing α,ω-dihydroxy polydimethylsiloxane, core-shell nano calcium carbonate filler and plasticizer to obtain a semi-finished product;

[0054] S2: adding a cross-linking agent, a coupling agent, a polymer antibacterial agent and a catalyst to the semi-finished product, stirring, and obtaining the silicone sealant.

[0055] In some embodiments, step S1 specifically includes the following steps: adding α,ω-dihydroxy polydimethylsiloxane, core-shell nano calcium carbonate filler and plasticizer into a kneader for mixing, heating to 120-140° C., evacuating to above -0.095 MPa for 2-3 hours to obtain a semi-finished product, and cooling to room temperature;

[0056] Step S2 specifically includes the following steps: adding a crosslinking agent, a coupling agent, a polymer antibacterial agent and a catalyst to the semi-finished product, stirring for 20 to 40 minutes under a vacuum degree of -0.095 MPa or above, and then storing the discharged product in a sealing cylinder to obtain the silicone sealant.

[0057] Example 1

[0058] The core-shell nano calcium carbonate silicone sealant of this embodiment includes the following raw materials in parts by weight:

[0059] 100 parts of α,ω-dihydroxypolydimethylsiloxane, 110 parts of core-shell nano calcium carbonate, 5 parts of dimethyl silicone oil, 12 parts of methyl tributylidene oxime silane, 1 part of γ-aminopropyltrimethoxysilane, 0.4 parts of polyhexamethyleneguanidine hydrochloride, and 0.2 parts of di-n-butyltin dilaurate.

[0060] The preparation method of the core-shell nano calcium carbonate silicone sealant of this embodiment comprises the following steps:

[0061] The preparation method of core-shell nano calcium carbonate is as follows: weigh a certain mass of calcium carbonate sample, prepare it into a calcium carbonate suspension with a mass fraction of 8%, add KH-560 (glycidyl ether propyl trimethoxy silane) accounting for 1.5% of nano calcium carbonate, stir and react in a water bath at 80°C for 6 hours, add excess chitosan oligosaccharide, control the material ratio of KH-560 modified calcium carbonate to chitosan oligosaccharide to 1:5, stir and react at 110°C for 8 hours, centrifuge the obtained product, wash with ethanol, and put it into a constant temperature vacuum drying oven.

[0062] S1: Add the α,ω-dihydroxy polydimethylsiloxane, core-shell nano calcium carbonate and dimethyl silicone oil into a kneader and mix evenly, heat to 120° C., evacuate to above -0.095 MPa for 2 hours, and cool the base material to room temperature.

[0063] S2: adding methyl tributylidene oxime silane, γ-aminopropyl trimethoxysilane, polyhexamethylene guanidine hydrochloride and di-n-butyl tin dilaurate to the base material cooled to room temperature, stirring for 30 minutes under a vacuum degree of -0.095 MPa or above, and then storing the material in a sealed cylinder to obtain the core-shell nano calcium carbonate silicone sealant.

[0064] Example 2

[0065] The core-shell nano calcium carbonate silicone sealant of this embodiment includes the following raw materials in parts by weight:

[0066] 100 parts of α,ω-dihydroxypolydimethylsiloxane, 110 parts of core-shell nano calcium carbonate, 5 parts of dimethyl silicone oil, 12 parts of vinyl tributanoximosilane, 1 part of γ-aminopropyltrimethoxysilane, 0.8 parts of polyhexamethyleneguanidine hydrochloride, and 0.2 parts of di-n-butyltin dilaurate.

[0067] The preparation method is the same as in Example 1, and the preparation method and raw materials of the core-shell nano calcium carbonate are the same as in Example 1.

[0068] Example 3

[0069] The core-shell nano calcium carbonate silicone sealant of this embodiment includes the following raw materials in parts by weight:

[0070] 100 parts of α,ω-dihydroxypolydimethylsiloxane, 120 parts of core-shell nano calcium carbonate, 5 parts of dimethyl silicone oil, 12 parts of methyl tri(methyl isobutyl ketoxime) silane, 1 part of γ-glycidyl ether oxypropyl trimethoxy silane, 0.4 parts of dodecyl dimethyl benzyl ammonium chloride, and 0.2 parts of di-n-butyl tin dilaurate.

[0071] The preparation method is the same as in Example 1, and the preparation method and raw materials of the core-shell nano calcium carbonate are the same as in Example 1.

[0072] Example 4

[0073] The core-shell nano calcium carbonate silicone sealant of this embodiment includes the following raw materials in parts by weight:

[0074] 100 parts of α,ω-dihydroxypolydimethylsiloxane, 120 parts of core-shell nano calcium carbonate, 5 parts of dimethyl silicone oil, 12 parts of vinyl tri(methyl isobutyl ketoxime) silane, 1 part of γ-glycidyl ether oxypropyl trimethoxy silane, 0.8 parts of dodecyl dimethyl benzyl ammonium chloride, and 0.2 parts of di-n-butyl tin diacetate.

[0075] The preparation method is the same as that of Example 1, wherein, in the preparation of core-shell nano calcium carbonate, the material ratio of KH-560 modified calcium carbonate to chitosan oligosaccharide is 1:5, and the reaction is stirred at 140° C. for 10 h.

[0076] Example 5

[0077] The core-shell nano calcium carbonate silicone sealant of this embodiment includes the following raw materials in parts by weight:

[0078] 100 parts of α,ω-dihydroxypolydimethylsiloxane, 130 parts of core-shell nano calcium carbonate, 5 parts of dimethyl silicone oil, 9 parts of methyl tributylidene oxime silane, 3 parts of vinyl tributylidene oxime silane, 1 part of γ-(2,3-epoxypropyl)propyltriethoxysilane, 0.4 parts of BBIT, and 0.2 parts of di-n-butyltin diacetate.

[0079] The preparation method is the same as that of Example 1, wherein, in the preparation of core-shell nano calcium carbonate, the material ratio of KH-560 modified calcium carbonate to chitosan oligosaccharide is 1:8, and the reaction is stirred at 110° C. for 8 h.

[0080] Example 6

[0081] The core-shell nano calcium carbonate silicone sealant of this embodiment includes the following raw materials in parts by weight:

[0082] 100 parts of α,ω-dihydroxypolydimethylsiloxane, 130 parts of core-shell nano calcium carbonate, 5 parts of dimethyl silicone oil, 9 parts of methyl tributylidene oxime silane, 3 parts of vinyl tris (methyl isobutyl ketoxime) silane, 1 part of γ-(2,3-epoxypropyl)propyltriethoxysilane, 0.8 parts of BBIT, and 0.2 parts of di-n-butyltin diacetate.

[0083] The preparation method is the same as that of Example 1, wherein, in the preparation of core-shell nano calcium carbonate, the material ratio of KH-560 modified calcium carbonate to chitosan oligosaccharide is 1:8, and the reaction is stirred at 140° C. for 10 h.

[0084] Example 7

[0085] The core-shell nano calcium carbonate silicone sealant of this embodiment includes the following raw materials in parts by weight:

[0086] 100 parts of α,ω-dihydroxypolydimethylsiloxane, 140 parts of core-shell nano calcium carbonate, 5 parts of dimethyl silicone oil, 9 parts of methyl tris(methyl isobutyl ketoxime) silane, 3 parts of vinyl tributyketoxime silane, 1 part of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, 0.4 parts of polyhexamethyleneguanidine hydrochloride, 0.4 parts of BBIT, and 0.2 parts of stannous octoate.

[0087] The preparation method is the same as that of Example 1, wherein, in the preparation of core-shell nano calcium carbonate, the material ratio of KH-560 modified calcium carbonate to chitosan oligosaccharide is 1:8, and the reaction is stirred at 110° C. for 8 h.

[0088] Example 8

[0089] The core-shell nano calcium carbonate silicone sealant of this embodiment includes the following raw materials in parts by weight:

[0090] 100 parts of α,ω-dihydroxypolydimethylsiloxane, 140 parts of core-shell nano calcium carbonate, 5 parts of dimethyl silicone oil, 9 parts of methyl tris(methyl isobutyl ketoxime) silane, 3 parts of vinyl tris(methyl isobutyl ketoxime) silane, 1 part of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, 0.4 parts of dodecyldimethylbenzyl ammonium chloride, 0.4 parts of BBIT, and 0.2 parts of stannous octoate.

[0091] The preparation method is the same as that of Example 1, wherein, in the preparation of core-shell nano calcium carbonate, the material ratio of KH-560 modified calcium carbonate to chitosan oligosaccharide is 1:5, and the reaction is stirred at 140° C. for 10 h.

[0092] Example 9

[0093] The core-shell nano calcium carbonate silicone sealant of this embodiment includes the following raw materials in parts by weight:

[0094] 100 parts of α,ω-dihydroxypolydimethylsiloxane, 80 parts of core-shell nano calcium carbonate, 2 parts of dimethyl silicone oil, 8 parts of methyl tributylidene oxime silane, 0.5 parts of γ-aminopropyltrimethoxysilane, 0.2 parts of polyhexamethyleneguanidine hydrochloride, and 0.01 parts of di-n-butyltin dilaurate.

[0095] The preparation method is the same as that of Example 1, wherein, in the preparation of core-shell nano calcium carbonate, the material ratio of KH-560 modified calcium carbonate to chitosan oligosaccharide is 1:2, and the reaction is stirred at 140° C. for 10 h.

[0096] Example 10

[0097] The core-shell nano calcium carbonate silicone sealant of this embodiment includes the following raw materials in parts by weight:

[0098] 100 parts of α,ω-dihydroxypolydimethylsiloxane, 140 parts of core-shell nano calcium carbonate, 10 parts of dimethyl silicone oil, 20 parts of methyl tributylidene oxime silane, 3 parts of γ-aminopropyltrimethoxysilane, 0.8 parts of polyhexamethyleneguanidine hydrochloride, and 1.5 parts of di-n-butyltin dilaurate.

[0099] The preparation method is the same as that of Example 1, wherein, in the preparation of core-shell nano calcium carbonate, the material ratio of KH-560 modified calcium carbonate to chitosan oligosaccharide is 1:10, and the reaction is stirred at 140° C. for 10 h.

[0100] Embodiment 11

[0101] The core-shell nano calcium carbonate silicone sealant of this embodiment has the same other components and contents as those of Example 1, except that in the preparation of the core-shell nano calcium carbonate, the material ratio of KH-560 modified calcium carbonate to chitosan oligosaccharide is 1:2, and the reaction is stirred at 140° C. for 8 h.

[0102] Example 12

[0103] The core-shell nano calcium carbonate silicone sealant of this embodiment has the same other components and contents as those of Example 1, except that in the preparation of the core-shell nano calcium carbonate, the material ratio of KH-560 modified calcium carbonate to chitosan oligosaccharide is 1:2, and the reaction is stirred at 110° C. for 8 h.

[0104] Comparative Example 1

[0105] The core-shell nano calcium carbonate silicone sealant of this comparative example comprises the following raw materials in parts by weight:

[0106] 100 parts of α,ω-dihydroxypolydimethylsiloxane, 110 parts of nano calcium carbonate, 5 parts of dimethyl silicone oil, 12 parts of methyl tributylidene oxime silane, 1 part of γ-aminopropyltrimethoxysilane, 0.4 parts of polyhexamethyleneguanidine hydrochloride, and 0.2 parts of di-n-butyltin dilaurate.

[0107] The preparation method is the same as that of Example 1, except that the nano calcium carbonate is not modified with chitosan oligosaccharide.

[0108] Comparative Example 2

[0109] The core-shell nano calcium carbonate silicone sealant of this comparative example comprises the following raw materials in parts by weight:

[0110] 100 parts of α,ω-dihydroxypolydimethylsiloxane, 110 parts of core-shell nano calcium carbonate, 5 parts of dimethyl silicone oil, 12 parts of methyl tributylidene oxime silane, 1 part of γ-aminopropyltrimethoxysilane, and 0.2 parts of di-n-butyltin dilaurate.

[0111] The preparation method is the same as that of Example 1, except that no polymer antibacterial agent is added.

[0112] The surface drying time of each embodiment and comparative example is measured according to GB / T 13477; the tensile strength is measured according to GB / T 528; the antibacterial performance is measured by the inhibition zone method; the measurement results are shown in Table 1 below.

[0113] Table 1 Performance determination of antibacterial RTV

[0114]

[0115] According to Examples 1-12 and Comparative Examples 1-2, the present invention introduces chitosan oligosaccharide into nano-calcium carbonate to form core-shell nano-calcium carbonate, and introduces a polymer antibacterial agent, and the RTV finally prepared has good overall antibacterial properties against Staphylococcus aureus and Escherichia coli, and has suitable surface drying time and tensile strength;

[0116] It can be seen from Examples 1.3.5 and 2.4.6.8 that when the amount of polymer antimicrobial agent added remains unchanged, the antimicrobial properties of RTV gradually improve with the increase in the amount of core-shell nano-calcium carbonate added;

[0117] It can be seen from Examples 1-2 and Comparative Examples 1-2 that the antibacterial properties of Comparative Example 1, which uses nano-calcium carbonate without chitosan oligosaccharide modification to prepare RTV, and Comparative Example 2, which uses only core-shell nano-calcium carbonate but does not add a high molecular antibacterial agent, are both inferior to those of Examples 1-2.

[0118] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A core-shell nano calcium carbonate filler, characterized in that: include: A calcium carbonate core layer, a silane coupling agent intermediate shell layer and a chitosan oligosaccharide outer shell layer; the silane coupling agent intermediate shell layer is wrapped outside the calcium carbonate core layer; and the chitosan oligosaccharide outer shell layer is wrapped outside the silane coupling agent intermediate shell layer.

2. The core-shell nano calcium carbonate filler according to claim 1, characterized in that: The intermediate shell layer of the silane coupling agent is wrapped around the calcium carbonate core layer through chemical adsorption; the intermediate shell layer of the silane coupling agent is connected to the outer shell layer of the chitosan oligosaccharide through chemical bonds.

3. The core-shell nano calcium carbonate filler according to claim 1, characterized in that: The particle size of the calcium carbonate core layer is 60-80nm, and the thickness of the chitosan oligosaccharide outer shell layer is 20-22nm.

4. The core-shell nano calcium carbonate filler according to claim 1, characterized in that: The silane coupling agent is silane coupling agent KH-560.

5. A method for preparing a core-shell nano calcium carbonate as claimed in any one of claims 1 to 4, characterized in that: include: The calcium carbonate is prepared into a calcium carbonate suspension, and a silane coupling agent is added to react to obtain calcium carbonate modified with the silane coupling agent; Then, chitosan oligosaccharide is added to the calcium carbonate modified by the silane coupling agent to react to obtain a product, and the product is separated to obtain the core-shell nano calcium carbonate.

6. The preparation method of core-shell nano calcium carbonate according to claim 5, wherein: When the silane coupling agent is added for reaction, the mass of the silane coupling agent is 0.5% to 2% of the calcium carbonate; the reaction temperature is 70 to 90° C., and the reaction time is 6 to 8 hours; When chitosan oligosaccharide is added to the calcium carbonate modified by the silane coupling agent for reaction, the molar ratio of the calcium carbonate modified by the silane coupling agent to the chitosan oligosaccharide is controlled to be 1:2-10, the reaction temperature is 110-120° C., and the reaction time is 8-10 hours.

7. A silicone sealant, characterized in that: Including the following raw materials by mass: 100 parts of α,ω-dihydroxypolydimethylsiloxane, 80-140 parts of the core-shell nano calcium carbonate filler according to any one of claims 1 to 4, 2-10 parts of a plasticizer, 8-20 parts of a crosslinking agent, 0.5-3 parts of a coupling agent, 0.2-0.8 parts of a polymer antibacterial agent, and 0.01-1.5 parts of a catalyst.

8. The silicone sealant according to claim 7, characterized in that: The viscosity of the α,ω-dihydroxy polydimethylsiloxane at 25° C. is 20,000 to 100,000 mPa.s; The plasticizer is dimethyl silicone oil, and the viscosity of the dimethyl silicone oil at 25° C. is 100 to 10000 mpa.s; The crosslinking agent is one or a mixture of methyl tributylacetoximosilane, vinyl tributylacetoximosilane, methyl tris(methyl isobutyl ketoxime) silane, and vinyl tris(methyl isobutyl ketoxime) silane; The coupling agent is one or a mixture of γ-aminopropyltrimethoxysilane, γ-glycidyloxypropyltrimethoxysilane, γ-(2,3-epoxypropyl)propyltriethoxysilane, and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane; The polymer antibacterial agent is one or a mixture of polyhexamethyleneguanidine hydrochloride, dodecyldimethylbenzyl ammonium chloride, n-butyl-1,2-benzisothiazolin-3-one (BBIT); The catalyst is one or a mixture of di-n-butyltin dilaurate, di-n-butyltin diacetate and stannous octoate.

9. A method for preparing a silicone sealant as claimed in claim 7, characterized in that: The steps include: S1: mixing α,ω-dihydroxy polydimethylsiloxane, core-shell nano calcium carbonate filler and plasticizer to obtain a semi-finished product; S2: adding a cross-linking agent, a coupling agent, a polymer antibacterial agent and a catalyst to the semi-finished product, stirring, and obtaining the silicone sealant.

10. The method for preparing the core-shell nano calcium carbonate silicone sealant according to claim 9, characterized in that: Step S1 specifically includes the following steps: adding α,ω-dihydroxy polydimethylsiloxane, core-shell nano calcium carbonate filler and plasticizer into a kneader for mixing, heating to 120-140° C., evacuating to above -0.095 MPa for 2-3 hours to obtain a semi-finished product, and cooling to room temperature; Step S2 specifically includes the following steps: adding a crosslinking agent, a coupling agent, a polymer antibacterial agent and a catalyst to the semi-finished product, stirring for 20 to 40 minutes under a vacuum degree of -0.095 MPa or above, and then storing the discharged product in a sealing cylinder to obtain the silicone sealant.

Images