Silicone sealant for construction

Abstract

The present invention relates to the technical field of sealant preparation, and specifically discloses a silicone sealant for construction. The silicone sealant for construction is prepared with polydimethylsiloxane as raw material, and the raw material for preparing the silicone sealant for construction contains a composite antibacterial agent; the composite antibacterial agent is composed of an inorganic antibacterial agent and a natural antibacterial agent. The inorganic antibacterial agent is selected from one or a combination of more than one of nano silver oxide, nano zinc oxide and nano titanium dioxide. The natural antibacterial agent is litchi leaf extract. The silicone sealant for construction of the present invention not only has an antibacterial effect on conventional bacteria, but also has an inhibitory effect on methicillin-resistant Staphylococcus aureus; it can be used in occasions with higher antibacterial requirements.

Description

Technical Field

[0001] The invention relates to the technical field of sealant preparation, and in particular to a silicone sealant for construction. Background Art

[0002] Sealant is an adhesive used to fill structural gaps to achieve a sealing effect. It needs to deform with the shape of the sealing surface, not be easy to flow, and have a certain degree of adhesion. It can play at least one or more roles such as preventing leakage, waterproofing, anti-vibration and sound insulation.

[0003] Silicone sealant is the most common type of sealant and is widely used in kitchens and bathrooms. Since kitchens and bathrooms are usually in a relatively dark and humid environment, it is easy for bacteria to grow if ordinary silicone sealants are used. Methicillin-resistant Staphylococcus aureus is a common and highly toxic bacterium in clinical practice and a superbug. It is one of the important pathogens of hospital and community infections. However, although some existing silicone sealants have antibacterial effects, their antibacterial effects on methicillin-resistant Staphylococcus aureus are not significant. Therefore, it is necessary to provide a silicone sealant that has the effect of inhibiting methicillin-resistant Staphylococcus aureus, which is used in hospitals and other places with high requirements for antibacterial effects, and is of great significance for inhibiting the spread of methicillin-resistant Staphylococcus aureus.

[0004] The applicant of the present invention disclosed a silicone sealant with anti-mildew effect in the previous patent 202111296960.3, which has an inhibitory effect on methicillin-resistant Staphylococcus aureus by adding a mildew inhibitor composed of nano zinc oxide and camphor powder extract to the silicone sealant. However, there are not many antibacterial agents that can be used in silicone sealants and have an inhibitory effect on methicillin-resistant Staphylococcus aureus; when the source of antibacterial agent raw materials is limited, it will affect normal production. Therefore, more antibacterial agents that can be used in silicone sealants and have an inhibitory effect on methicillin-resistant Staphylococcus aureus need to be further developed and improved. On the other hand, the patent's antibacterial agent composed of nano zinc oxide and camphor powder extract needs to be prepared using a special dispersant to obtain a silicone sealant in order to exert the best antibacterial effect on methicillin-resistant Staphylococcus aureus, which also needs further improvement. Summary of the invention

[0005] In order to overcome at least one of the technical problems existing in the prior art, the present invention provides a silicone sealant for construction.

[0006] The technical solution of the present invention to solve the above technical problems is as follows:

[0007] A silicone sealant for construction, which is prepared using polydimethylsiloxane as a raw material, wherein the raw material for preparing the silicone sealant for construction contains a composite antibacterial agent;

[0008] The composite antibacterial agent consists of an inorganic antibacterial agent and a natural antibacterial agent.

[0009] Preferably, the natural antibacterial agent is litchi leaf extract.

[0010] The inventors found in their research that litchi leaf extract has an antibacterial effect on methicillin-resistant Staphylococcus aureus; therefore, a composite antibacterial agent containing litchi leaf extract is added to silicone sealant, which makes the prepared silicone sealant also have an antibacterial effect on methicillin-resistant Staphylococcus aureus.

[0011] Preferably, the litchi leaf extract is prepared by the following method:

[0012] Take litchi leaves, add organic solvent, heat and reflux for extraction for 1-2 hours, concentrate the extract, and dry to obtain litchi leaf organic solvent extract, namely the litchi leaf extract.

[0013] Preferably, the organic solvent is selected from n-heptane.

[0014] The inventors found in their research that the choice of organic solvent for extraction plays an important role in whether the prepared litchi leaf extract can exert a good antibacterial effect on methicillin-resistant Staphylococcus aureus in silicone sealant. The inventors surprisingly found in a large number of experiments that when the litchi leaf extract prepared by using n-heptane as the organic solvent can exert a good antibacterial effect on methicillin-resistant Staphylococcus aureus in silicone sealant; when litchi leaf extract prepared by using n-heptane is added to silicone sealant, its antibacterial effect on methicillin-resistant Staphylococcus aureus is significantly higher than that of litchi leaf extract prepared by using other solvents or organic solvents.

[0015] Preferably, the weight amount of the organic solvent is 5 to 10 times the weight of the litchi leaves.

[0016] Most preferably, the weight amount of the organic solvent is 8 times the weight of the litchi leaves.

[0017] Preferably, the preparation method of the litchi leaf extract further comprises a macroporous resin column chromatography step; the specific method of the macroporous resin column chromatography is:

[0018] The organic solvent extract of litchi leaves is loaded onto a macroporous resin column, and then eluted with a 65-70% acetone solution, and the eluate is discarded; then eluted with an 85-90% acetone solution, the eluate eluted with the 85-90% acetone solution is collected, and the litchi leaf extract is obtained after concentrating and drying.

[0019] Further preferably, the specific method of the macroporous resin column chromatography is:

[0020] The organic solvent extract of litchi leaves is loaded onto a macroporous resin column, and then eluted with a 68% acetone solution, and the eluate is discarded; then eluted with an 88% acetone solution, the eluate eluted with the 88% acetone solution is collected, and the litchi leaf extract is obtained after concentrating and drying.

[0021] In the macroporous resin column chromatography of the present invention, the ketone solution refers to an acetone aqueous solution; the percentage of the acetone solution refers to the volume percentage.

[0022] The inventors found in further research that the inhibitory effect of the litchi leaf extract on methicillin-resistant Staphylococcus aureus was further significantly improved by further passing the litchi leaf organic solvent extract through the macroporous resin column chromatography of the present invention. Compared with the addition of the litchi leaf organic solvent extract prepared by n-heptane, the inhibitory effect of the litchi leaf extract on methicillin-resistant Staphylococcus aureus was further significantly improved by adding the litchi leaf extract further prepared through the macroporous resin column chromatography of the present invention to the silicone sealant.

[0023] The inventors surprisingly found in the research that the elution conditions of the macroporous resin column of the present invention are very critical; adding litchi leaf extracts prepared under any macroporous resin elution conditions to the silicone sealant can not significantly improve its antibacterial effect on methicillin-resistant Staphylococcus aureus; only adding litchi leaf extracts prepared under the macroporous resin elution conditions of the present invention to the silicone sealant can significantly improve its antibacterial effect on methicillin-resistant Staphylococcus aureus; while adding litchi leaf extracts prepared under other macroporous resin elution conditions to the silicone sealant cannot significantly improve its antibacterial effect on methicillin-resistant Staphylococcus aureus, and its antibacterial effect on methicillin-resistant Staphylococcus aureus may even decrease.

[0024] Preferably, the macroporous resin column is an AB-8 macroporous resin column.

[0025] Preferably, the natural antibacterial agent further comprises N-(2-hydroxyethyl) dodecylamide and trimethyl ammonium soya oil chloride.

[0026] Preferably, the weight ratio of the litchi leaf extract to N-(2-hydroxyethyl) dodecylamide and trimethyl ammonium soya oil chloride in the natural antibacterial agent is 7-10:1-3:1-3;

[0027] Most preferably, the weight ratio of litchi leaf extract to N-(2-hydroxyethyl) dodecylamide and trimethyl ammonium soya oil chloride in the natural antibacterial agent is 8:1:1.

[0028] In further research, the inventors surprisingly found that adding a natural antibacterial agent composed of litchi leaf extract, N-(2-hydroxyethyl) dodecylamide and trimethyl ammonium soy chloride to silicone sealant can further significantly improve its antibacterial effect on methicillin-resistant Staphylococcus aureus compared to adding litchi leaf extract alone.

[0029] Preferably, the inorganic antibacterial agent is selected from one or a combination of nano silver oxide, nano zinc oxide and nano titanium dioxide.

[0030] Preferably, the weight ratio of the inorganic antibacterial agent to the natural antibacterial agent is 5 to 10:1.

[0031] Most preferably, the weight ratio of the inorganic antibacterial agent to the natural antibacterial agent is 9:1.

[0032] Beneficial effects: In the composite antibacterial agent described in the present invention, since the inorganic antibacterial agent can exert an antibacterial effect on conventional bacteria; the natural antibacterial agent can have an antibacterial effect on methicillin-resistant Staphylococcus aureus; therefore, the construction silicone sealant added with the composite antibacterial agent composed of inorganic antibacterial agents and natural antibacterial agents of the present invention can not only have an antibacterial effect on conventional bacteria, but also have an inhibitory effect on methicillin-resistant Staphylococcus aureus. In addition, compared with the applicant's previous patent 202111296960.3, the composite antibacterial agent described in the present invention does not need to add a special dispersant, and can play an excellent inhibitory effect on methicillin-resistant Staphylococcus aureus in the construction silicone sealant. DETAILED DESCRIPTION

[0033] The present invention is further explained below in conjunction with specific examples, but the examples do not limit the present invention in any form.

[0034] The polydimethylsiloxane in the following examples all has a viscosity (25°C cp) of 5000. The remaining raw materials not specified are all conventional raw materials that can be purchased by those skilled in the art through conventional purchase channels or prepared by conventional methods.

[0035] Example 1 Preparation of silicone sealant for construction

[0036] The raw materials are composed by weight: 70 parts of polydimethylsiloxane; 20 parts of nano calcium carbonate; 6 parts of cross-linking agent methyltrimethoxysilane; 1 part of catalyst dibutyltin dilaurate; 1 part of composite antibacterial agent; 2 parts of composite dispersant;

[0037] The composite dispersant is composed of dispersant A and dispersant B in a weight ratio of 2:1; the dispersant A is tristearate glyceryl; the dispersant B is zinc stearate;

[0038] The composite antibacterial agent is composed of nano zinc oxide and natural antibacterial agent in a weight ratio of 9:1;

[0039] The natural antibacterial agent is litchi leaf extract; the litchi leaf extract is prepared by the following method:

[0040] Take dried litchi leaves, then add 8 times the weight of an organic solvent and heat to boiling state, perform reflux extraction for 1.5 hours, concentrate the extract, and then dry to obtain a litchi leaf organic solvent extract, namely the litchi leaf extract;

[0041] The organic solvent is n-heptane;

[0042] The preparation method of silicone sealant for construction is as follows: firstly, polydimethylsiloxane, nano-calcium carbonate, composite antibacterial agent and composite dispersant are put into a high-speed mixer, and stirred for 30 minutes at a vacuum degree of -0.05Mpa; then, cross-linking agent methyltrimethoxysilane and catalyst dibutyltin dilaurate are added, and stirred for 120 minutes at a vacuum degree of -0.09Mpa to obtain the silicone sealant for construction.

[0043] Example 2 Preparation of silicone sealant for construction

[0044] The composition by weight of raw materials and the preparation method of Example 2 are the same as those of Example 1.

[0045] The difference between Example 2 and Example 1 is that the preparation method of litchi leaf extract is different; on the basis of Example 1, the litchi leaf extract of Example 2 is further prepared by macroporous resin column chromatography.

[0046] The litchi leaf extract is prepared by the following method:

[0047] (1) taking dried litchi leaves, adding 8 times the weight of an organic solvent, heating to boiling, performing reflux extraction for 1.5 hours, concentrating the extract, and drying to obtain an organic solvent extract of litchi leaves;

[0048] (2) The organic solvent extract of litchi leaves is loaded onto a macroporous resin column (the macroporous resin column is filled with AB-8 macroporous resin, and the weight of AB-8 macroporous resin is 30 times that of the organic solvent extract of litchi leaves), and then eluted with 3BV of 68% acetone solution at a flow rate of 3BV / h, and the eluate is discarded; then eluted with 6BV of 88% acetone solution at a flow rate of 3BV / h, and the eluate eluted with 88% acetone solution is collected, and the litchi leaf extract is obtained after concentration and drying.

[0049] Example 3 Preparation of silicone sealant for construction

[0050] The raw material composition by weight and the preparation method of Example 3 are the same as those of Example 1.

[0051] The difference between Example 3 and Example 1 is that the preparation method of litchi leaf extract is different; the litchi leaf extract of Example 3 is further prepared by macroporous resin column chromatography on the basis of Example 1.

[0052] The litchi leaf extract is prepared by the following method:

[0053] (1) taking dried litchi leaves, adding 5 times the weight of an organic solvent, heating to boiling, performing reflux extraction for 2 hours, concentrating the extract, and drying to obtain an organic solvent extract of litchi leaves;

[0054] (2) The organic solvent extract of litchi leaves is loaded onto a macroporous resin column (the macroporous resin column is filled with AB-8 macroporous resin, and the weight of AB-8 macroporous resin is 30 times that of the organic solvent extract of litchi leaves), and then eluted with 2BV of 65% acetone solution at a flow rate of 2BV / h, and the eluate is discarded; then eluted with 4BV of 90% acetone solution at a flow rate of 2BV / h, and the eluate eluted with 90% acetone solution is collected, and the litchi leaf extract is obtained after concentration and drying.

[0055] Example 4 Preparation of silicone sealant for construction

[0056] The raw material composition by weight and the preparation method of Example 4 are the same as those of Example 1.

[0057] The difference between Example 4 and Example 1 is that the preparation method of litchi leaf extract is different; the litchi leaf extract of Example 4 is further prepared by macroporous resin column chromatography on the basis of Example 1.

[0058] The litchi leaf extract is prepared by the following method:

[0059] (1) taking dried litchi leaves, adding 10 times the weight of an organic solvent, heating to boiling, performing reflux extraction for 1 hour, concentrating the extract, and drying to obtain an organic solvent extract of litchi leaves;

[0060] (2) The organic solvent extract of litchi leaves is loaded onto a macroporous resin column (the macroporous resin column is filled with AB-8 macroporous resin, and the weight of AB-8 macroporous resin is 30 times that of the organic solvent extract of litchi leaves), and then eluted with 4BV of 70% acetone solution at a flow rate of 2BV / h, and the eluate is discarded; then eluted with 5BV of 85% acetone solution at a flow rate of 2BV / h, and the eluate eluted with 85% acetone solution is collected, and the litchi leaf extract is obtained after concentration and drying.

[0061] Example 5

[0062] The raw material composition by weight and the preparation method of Example 5 are the same as those of Example 1.

[0063] The difference between Example 5 and Example 1 is that the preparation method of the litchi leaf extract is different; the organic solvent used in the preparation process of the litchi leaf extract in Example 5 is different.

[0064] The litchi leaf extract is prepared by the following method:

[0065] Take dried litchi leaves, then add 8 times the weight of an organic solvent and heat to boiling state, perform reflux extraction for 1.5 hours, concentrate the extract, and then dry to obtain a litchi leaf organic solvent extract, namely the litchi leaf extract;

[0066] The organic solvent is methanol.

[0067] Example 6

[0068] The raw material composition by weight and the preparation method of Example 6 are the same as those of Example 1.

[0069] The difference between Example 6 and Example 1 is that the preparation method of litchi leaf extract is different; the organic solvent used in the preparation process of litchi leaf extract in Example 6 is different.

[0070] The litchi leaf extract is prepared by the following method:

[0071] Take dried litchi leaves, then add 8 times the weight of an organic solvent and heat to boiling state, perform reflux extraction for 1.5 hours, concentrate the extract, and then dry to obtain a litchi leaf organic solvent extract, namely the litchi leaf extract;

[0072] The organic solvent is acetone.

[0073] Example 7

[0074] The raw material composition by weight and the preparation method of Example 7 are the same as those of Example 1.

[0075] The difference between Example 7 and Example 1 is that the preparation method of litchi leaf extract is different; the solvent used in the preparation process of litchi leaf extract in Example 7 is different.

[0076] The litchi leaf extract is prepared by the following method:

[0077] Take dried litchi leaves, then add 8 times the weight of solvent and heat to boiling state, perform reflux extraction for 1.5 hours, concentrate the extract, and then dry to obtain litchi leaf organic solvent extract, i.e., the litchi leaf extract;

[0078] The solvent is water.

[0079] Example 8 Preparation of silicone sealant for construction

[0080] The raw material composition by weight and the preparation method of Example 8 are the same as those of Example 1.

[0081] The difference between Example 8 and Example 2 is that the composition of the natural antibacterial agent is different.

[0082] The natural antibacterial agent of Example 8 is prepared by mixing litchi leaf extract, N-(2-hydroxyethyl) dodecylamide and trimethyl ammonium soya oil chloride in a weight ratio of 8:1:1;

[0083] The preparation method of the litchi leaf extract is the same as that in Example 2.

[0084] Comparative Example 1 Preparation of silicone sealant for construction

[0085] The raw material composition by weight and the preparation method of Comparative Example 2 are the same as those of Example 2.

[0086] The difference between Comparative Example 1 and Example 2 is that the macroporous resin elution conditions in the preparation process of litchi leaf extract are different;

[0087] The litchi leaf extract is prepared by the following method:

[0088] (1) taking dried litchi leaves, adding 8 times the weight of an organic solvent, heating to boiling, performing reflux extraction for 1.5 hours, concentrating the extract, and drying to obtain an organic solvent extract of litchi leaves;

[0089] (2) The organic solvent extract of litchi leaves is loaded onto a macroporous resin column (the macroporous resin column is filled with AB-8 macroporous resin, and the weight of AB-8 macroporous resin is 30 times that of the organic solvent extract of litchi leaves), and then eluted with water at a flow rate of 3 BV / h, and the eluate is discarded; then eluted with 6 BV of 30% acetone solution at a flow rate of 3 BV / h, and the eluate eluted with the 30% acetone solution is collected, and the litchi leaf extract is obtained after concentration and drying.

[0090] Comparative Example 2 Preparation of silicone sealant for construction

[0091] The raw material composition by weight and the preparation method of Comparative Example 2 are the same as those of Example 2.

[0092] The difference between Comparative Example 2 and Example 2 is that the macroporous resin elution conditions in the preparation process of litchi leaf extract are different;

[0093] The litchi leaf extract is prepared by the following method:

[0094] (1) taking dried litchi leaves, adding 8 times the weight of an organic solvent, heating to boiling, performing reflux extraction for 1.5 hours, concentrating the extract, and drying to obtain an organic solvent extract of litchi leaves;

[0095] (2) The organic solvent extract of litchi leaves is loaded onto a macroporous resin column (the macroporous resin column is filled with AB-8 macroporous resin, and the weight of AB-8 macroporous resin is 30 times that of the organic solvent extract of litchi leaves), and then eluted with 3BV of 50% acetone solution at a flow rate of 3BV / h, and the eluate is discarded; then eluted with 6BV of 80% acetone solution at a flow rate of 3BV / h, and the eluate eluted with 80% acetone solution is collected, and the litchi leaf extract is obtained after concentration and drying.

[0096] Comparative Example 3 Preparation of silicone sealant for construction

[0097] The raw material composition by weight and the preparation method of Comparative Example 3 are the same as those of Example 2.

[0098] The difference between Comparative Example 3 and Example 2 is that the macroporous resin elution conditions in the preparation process of litchi leaf extract are different;

[0099] The litchi leaf extract is prepared by the following method:

[0100] (1) taking dried litchi leaves, adding 8 times the weight of an organic solvent, heating to boiling, performing reflux extraction for 1.5 hours, concentrating the extract, and drying to obtain an organic solvent extract of litchi leaves;

[0101] (2) The organic solvent extract of litchi leaves is loaded onto a macroporous resin column (the macroporous resin column is filled with AB-8 macroporous resin, and the weight of AB-8 macroporous resin is 30 times that of the organic solvent extract of litchi leaves), and then eluted with 3BV of 68% ethanol solution at a flow rate of 3BV / h, and the eluate is discarded; then eluted with 6BV of 88% ethanol solution at a flow rate of 3BV / h, the eluate eluted with 88% ethanol solution is collected, and the litchi leaf extract is obtained after concentration and drying.

[0102] Comparative Example 4 Preparation of silicone sealant for construction

[0103] The raw material composition by weight and the preparation method of Comparative Example 4 are the same as those of Example 8.

[0104] The difference between Comparative Example 4 and Example 8 is that the composition of the natural antibacterial agent is different. The natural antibacterial agent described in Comparative Example 4 is only a mixture of litchi leaf extract and N-(2-hydroxyethyl) dodecylamide.

[0105] The natural antibacterial agent of Comparative Example 4 is prepared by mixing litchi leaf extract and N-(2-hydroxyethyl) dodecylamide in a weight ratio of 8:2;

[0106] The preparation method of the litchi leaf extract is the same as that in Example 8.

[0107] Comparative Example 5 Preparation of silicone sealant for construction

[0108] The raw material composition by weight and the preparation method of Comparative Example 5 are the same as those of Example 8.

[0109] The difference between Comparative Example 5 and Example 8 is that the composition of the natural antibacterial agent is different. The natural antibacterial agent described in Comparative Example 5 is only a mixture of litchi leaf extract and trimethyl ammonium soya oil chloride.

[0110] The natural antibacterial agent of Comparative Example 5 is prepared by mixing litchi leaf extract and trimethyl ammonium soya oil chloride in a weight ratio of 8:2;

[0111] The preparation method of the litchi leaf extract is the same as that in Example 8.

[0112] Experimental Example 1

[0113] The silicone sealants for construction prepared in Examples 1 to 8 and Comparative Examples 1 to 5 were prepared into test strips according to the method specified in Appendix A of QB / T2591-2003, and the antibacterial performance was tested against methicillin-resistant Staphylococcus aureus (MRSA); the test results are shown in Table 1.

[0114] Table 1. Experimental results of antibacterial effect of silicone sealant for construction of the present invention

[0115]

[0116]

[0117] From the experimental results in Table 1, it can be seen that the antibacterial rate of the silicone sealant for construction prepared in Example 1 against methicillin-resistant Staphylococcus aureus is significantly higher than that of the silicone sealants for construction prepared in Examples 5 to 7. This shows that the selection of organic solvents during the extraction process plays an important role in whether the prepared litchi leaf extract can exert a good antibacterial effect on methicillin-resistant Staphylococcus aureus in silicone sealants. When litchi leaf extract prepared by n-heptane is added to silicone sealant, its antibacterial effect on methicillin-resistant Staphylococcus aureus is significantly higher than that of litchi leaf extract prepared by other solvents or organic solvents.

[0118] From the experimental results in Table 1, it can be seen that the antibacterial rate of the silicone sealant for construction prepared in Examples 2 to 4 against methicillin-resistant Staphylococcus aureus is much higher than that of the silicone sealant for construction prepared in Example 1; it has excellent antibacterial effect against methicillin-resistant Staphylococcus aureus. This shows that the addition of the litchi leaf extract further prepared by the above-mentioned macroporous resin column chromatography of the present invention to the silicone sealant has further significantly improved the antibacterial effect against methicillin-resistant Staphylococcus aureus compared with the addition of the litchi leaf organic solvent extract prepared by n-heptane.

[0119] However, the antibacterial rate of the silicone sealants for construction prepared in Comparative Examples 1 to 3 against methicillin-resistant Staphylococcus aureus was not significantly improved compared with that in Example 1, and was even reduced in Comparative Example 1. This shows that: the elution conditions of the macroporous resin column of the present invention are very critical; adding litchi leaf extracts prepared under any macroporous resin elution conditions to the silicone sealant can not significantly improve its antibacterial effect on methicillin-resistant Staphylococcus aureus; only adding litchi leaf extracts prepared under the macroporous resin elution conditions of the present invention to the silicone sealant can significantly improve its antibacterial effect on methicillin-resistant Staphylococcus aureus; while adding litchi leaf extracts prepared under other macroporous resin elution conditions to the silicone sealant cannot significantly improve its antibacterial effect on methicillin-resistant Staphylococcus aureus, and even its antibacterial effect on methicillin-resistant Staphylococcus aureus will decrease.

[0120] From the experimental results in Table 1, it can be seen that the antibacterial rate of the silicone sealant for construction prepared in Example 8 against methicillin-resistant Staphylococcus aureus is further significantly higher than that of the silicone sealant for construction prepared in Example 2; it has a very excellent antibacterial effect against methicillin-resistant Staphylococcus aureus. This shows that adding a natural antibacterial agent composed of litchi leaf extract, N-(2-hydroxyethyl) dodecylamide and trimethyl ammonium soy oil chloride to the silicone sealant can further significantly improve its antibacterial effect against methicillin-resistant Staphylococcus aureus compared to adding litchi leaf extract alone.

[0121] However, the antibacterial rate of the silicone sealants for construction prepared in Comparative Examples 4 and 5 against methicillin-resistant Staphylococcus aureus was not significantly improved compared with that in Example 2; and the antibacterial effect thereof was also significantly less than that in Example 8. This indicates that the antibacterial effect against methicillin-resistant Staphylococcus aureus can be further significantly improved only by adding the natural antibacterial agent composed of litchi leaf extract, N-(2-hydroxyethyl) dodecylamide and trimethyl ammonium soy oil chloride to the silicone sealant; while the antibacterial effect against methicillin-resistant Staphylococcus aureus cannot be further significantly improved by adding only the natural antibacterial agent composed of litchi leaf extract and N-(2-hydroxyethyl) dodecylamide, or only by adding the natural antibacterial agent composed of litchi leaf extract and trimethyl ammonium soy oil chloride.

Claims

1. A silicone sealant for construction, which is prepared from polydimethylsiloxane as a raw material, characterized in that: The raw materials for preparing the silicone sealant for construction contain a composite antibacterial agent; The composite antibacterial agent is composed of an inorganic antibacterial agent and a natural antibacterial agent; The natural antibacterial agent is litchi leaf extract; The litchi leaf extract is prepared by the following method: Take litchi leaves, add an organic solvent, heat and reflux for extraction for 1 to 2 hours, concentrate the extract, and dry to obtain an organic solvent extract of litchi leaves; the organic solvent is selected from n-heptane; The organic solvent extract of litchi leaves is loaded onto a macroporous resin column, and then eluted with a 65-70% acetone solution, and the eluate is discarded; then eluted with an 85-90% acetone solution, the eluate eluted with the 85-90% acetone solution is collected, and the litchi leaf extract is obtained after concentrating and drying.

2. The silicone sealant for construction according to claim 1, characterized in that: The weight amount of the organic solvent is 5 to 10 times the weight of the litchi leaves.

3. The silicone sealant for construction according to claim 2, characterized in that: The weight amount of the organic solvent is 8 times the weight of the litchi leaves.

4. The silicone sealant for construction according to claim 1, characterized in that: The specific method of the macroporous resin column chromatography is: The organic solvent extract of litchi leaves is loaded onto a macroporous resin column, and then eluted with a 68% acetone solution, and the eluate is discarded; then eluted with an 88% acetone solution, the eluate eluted with the 88% acetone solution is collected, and the litchi leaf extract is obtained after concentrating and drying.

5. The silicone sealant for construction according to claim 1, characterized in that: The macroporous resin column is an AB-8 macroporous resin column.

6. The silicone sealant for construction according to claim 1, characterized in that: The inorganic antibacterial agent is selected from one or a combination of nano silver oxide, nano zinc oxide and nano titanium dioxide.

7. The silicone sealant for construction according to claim 1, characterized in that: The weight ratio of the inorganic antibacterial agent to the natural antibacterial agent is 5 to 10:

1.

8. The silicone sealant for construction according to claim 7, characterized in that: The weight ratio of the inorganic antibacterial agent to the natural antibacterial agent is 9:1.

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