Modified nanosilica, method for preparing and using same, resin composition, and cured epoxy resin

Abstract

The application relates to the field of organic polymers, and discloses modified nano-silicon dioxide, a preparation method and application thereof, a resin composition and a cured epoxy resin, wherein the modified nano-silicon dioxide has a structure shown in formula (1): wherein M is a nano-silicon dioxide particle, x is an integer of 1-4, R is an alkyl group with 1-4 carbon atoms, n is an integer of 0-3, m is an integer of 1-3, n+m=3, A is a structural unit from an anhydride compound, and B is a structural unit from a polyamino compound. The modified nano-silicon dioxide has a high amino content, can bond with epoxy groups in the epoxy resin when added into the epoxy resin, fully plays the advantages between the two, makes the cured epoxy resin have a large compressive strength, and can improve the glass transition temperature, so that the epoxy resin is not easy to deform at high temperatures.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of organic polymers, in particular to a modified nano-silica, a preparation method and application thereof, a resin composition and a cured epoxy resin. BACKGROUND

[0002] Epoxy resin is a kind of traditional polymer material, which is applied in many sub-material fields, such as paint, adhesive, etc. Pure epoxy resin is mostly in liquid or viscous state, which must be combined with a curing agent to play a role when used as a polymer functional material. The curing agent contains a large number of active groups, which can react with the active sites in the resin, and the final solid material is obtained by cross-linking and curing. In actual industrial formulations, pigments, fillers, functional additives, etc. are added to the resin, such as a large amount of powder filler to increase the hardness of the material and reduce the cost. However, not all materials can increase the hardness by adding cheap powder, such as varnish which is most vulnerable to damage in anticorrosive paint, which needs to maintain transparency and high hardness, and such as the finish in floor paint, which needs strong wear resistance and good flowability, and cannot add too much powder. To solve these problems, the traditional solution is to continuously modify the resin and organic curing agent, which has achieved certain results. However, due to the inherent defects of organic polymer materials, the performance improvement is limited, so it is necessary to find another way to break through the inherent defects of organic polymer materials and essentially improve the performance of the material. SUMMARY

[0003] The purpose of the present application is to overcome the problems of poor curing performance and mechanical strength and high cost in the prior art, and to provide a modified nano-silica and a preparation method and application thereof. The modified nano-silica has a small particle size and a large specific surface area, and is well dispersed in the epoxy resin. The amino content in the modified nano-silica is high, and the amino groups on the surface of the nano-silica particles exhibit a dendritic morphology. When the modified nano-silica is added to the epoxy resin, it can react with the epoxy groups in the epoxy resin, fully exerting the advantages between the two, so that the cured epoxy resin has a large compressive strength, and the glass transition temperature is also improved, so that it is not easy to deform at high temperature.

[0004] To achieve the above purpose, the first aspect of the present application provides a modified nano-silica, characterized in that the modified nano-silica has a structure represented by formula (1):

[0005]

[0006] wherein M is a nano-silica particle, x is an integer of 1-4, and R is an alkyl group with a carbon atom number of 1-4;

[0007] n is an integer from 0 to 3, m is an integer from 1 to 3, n+m = 3;

[0008] A is a structural unit from an acid anhydride compound, and B is a structural unit from a polyamino compound.

[0009] The second aspect of the present application provides a method for preparing modified nanosilica, characterized in that the method comprises the following steps:

[0010] S1, dispersing nanosilica particles M in a first solvent in the presence of a protective gas, adding an amino silane to perform a first reaction, and obtaining amino-functionalized nanosilica represented by formula (3);

[0011]

[0012] S2, performing a second reaction of the amino-functionalized nanosilica with an acid anhydride compound in the presence of a second solvent, and obtaining carboxyl-functionalized nanosilica represented by formula (4);

[0013]

[0014] S3, mixing and activating the carboxyl-functionalized nanosilica with a condensing agent in the presence of a basic catalyst, and then adding a polyamino compound to perform a third reaction, and obtaining modified nanosilica.

[0015] The third aspect of the present application provides modified nanosilica prepared by the above method.

[0016] The fourth aspect of the present application provides the use of the above modified nanosilica as a curing agent in an epoxy resin.

[0017] The fifth aspect of the present application provides an epoxy resin composition, characterized in that the epoxy resin composition comprises a curing agent component and a resin component.

[0018] The curing agent component contains the modified nanosilica of the first aspect or the third aspect;

[0019] The resin component comprises an epoxy resin.

[0020] The curing agent component and the resin component are each independently present.

[0021] In the present application, the content of the modified nanosilica is 20-80 parts by weight based on 100 parts by weight of the epoxy resin.

[0022] In this invention, the epoxy resin composition may also contain emulsifiers, reinforcing agents, etc. commonly used in the art. There are no particular limitations on the types and amounts of emulsifiers and reinforcing agents, which can be conventional types and amounts in the art.

[0023] The sixth aspect of the present invention provides a cured epoxy resin, characterized in that the cured epoxy resin is prepared from the epoxy resin composition described in the fifth aspect of the present invention.

[0024] Through the above technical solutions, the modified nano-silica, its preparation method and application, resin composition and cured epoxy resin provided by the present invention achieve the following beneficial effects: the modified nano-silica has a small particle size and a large specific surface area, good dispersibility in epoxy resin, and high amino content. It exhibits a dendritic morphology on the surface of the nano-silica particles M. When added to epoxy resin, it can undergo a bonding reaction with the epoxy groups in the epoxy resin, giving full play to the advantages of both. This results in the cured epoxy resin having a large compressive strength and can also increase its glass transition temperature, making it less prone to deformation at high temperatures. Attached Figure Description

[0025] Figure 1 The image shows a photograph of modified nano-silica with an average particle size of 30 nm dispersed in water, as described in Example 1.

[0026] Figure 2 This is a TEM characterization image of the modified nano-silica with an average particle size of 30 nm prepared in Example 1.

[0027] Figure 3 This is a SEM characterization image of the modified nano-silica with an average particle size of 30 nm prepared in Example 1.

[0028] Figure 4 The image shows a photograph of the modified nano-silica with an average particle size of 200 nm dispersed in water, as described in Example 2.

[0029] Figure 5 This is a TEM characterization image of the modified nano-silica with an average particle size of 200 nm prepared in Example 2.

[0030] Figure 6 This is a SEM characterization image of the modified nano-silica with an average particle size of 200 nm prepared in Example 2. Detailed Implementation

[0031] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not critical to the invention. Any numeric range recited is intended to include all values from the lower value to the upper value, inclusive of both values, and to also include any value approximately or about the value. For numeric ranges, the endpoints are combined with the individual points to form new numeric ranges that are considered disclosed herein.

[0032] The first aspect of the present application provides a modified nanosilica, characterized in that the modified nanosilica has a structure shown in formula (1):

[0033]

[0034] wherein M is a nanosilica particle, x is an integer of 1-4, and R is an alkyl group with a carbon atom number of 1-4;

[0035] n is an integer of 0-3, m is an integer of 1-3, and n+m=3;

[0036] A is a structural unit from an acid anhydride compound, and B is a structural unit from a polyamino compound.

[0037] In the present application, by further modifying the nanosilica particle M with a polyamino group on the basis of carboxyl modification, a dendritic morphology is presented on the surface of the nanosilica particle M, which can occur bonding reaction with the epoxy groups in the epoxy resin when added to the epoxy resin, fully exerting the advantages between the two, so that the cured epoxy resin has a large compressive strength, and at the same time, the glass transition temperature is improved, so that it is not easy to deform at high temperature.

[0038] According to the present application, the acid anhydride compound is selected from at least one of maleic anhydride, phthalic anhydride and succinic anhydride.

[0039] According to the present application, the polyamino compound is a linear polyethylene polyamino compound having a structure shown in formula (2) or a non-linear polyethylene imine with a number average molecular weight of 300-3000:

[0040]

[0041] wherein p is an integer of 1-6.

[0042] Further, the molecular weight of the non-linear polyethylene imine is 1500-2500.

[0043] In the present application, the polyamino compound is selected from the above-mentioned compounds, so that the amino content in the modified nanosilica is high, and the curing performance on the epoxy resin is further improved.

[0044] In the present application, the polyethylene polyamino compound can be triethylene diamine, triethylene tetramine, pentaethylene hexamine or hexaethylene heptamine, etc.

[0045] According to the present application, the nano-silica particle M has a particle size of 10-500 nm and a specific surface area of 10-300 m 2 / g.

[0046] Further, the nano-silica particle M has a particle size of 30-200 nm and a specific surface area of 50-200 m 2 / g.

[0047] According to the present application, the modified nano-silica has a particle size of 10-500 nm and a specific surface area of 50-500 m 2 / g.

[0048] In the present application, when the particle size and the specific surface area of the modified nano-silica satisfy the above range, the smaller particle size has good dispersibility in the epoxy resin, thereby improving the curing performance of the epoxy resin.

[0049] Further, the modified nano-silica has a particle size of 30-500 nm and a specific surface area of 50-300 m 2 / g.

[0050] According to the present application, the modified nano-silica has an amino content of 0.1-5 mmol / g.

[0051] In the present application, when the amino content of the modified nano-silica satisfies the above range, the nano-particle surface can present a dendritic morphology, thereby improving the crosslinking speed and crosslinking density of the epoxy resin containing the modified nano-silica.

[0052] Further, the modified nano-silica has an amino content of 0.5-5 mmol / g.

[0053] The second aspect of the present application provides a method for preparing modified nano-silica, characterized in that the method comprises the following steps:

[0054] S1, dispersing the nano-silica particle M in a first solvent in the presence of a protective gas, adding amino silane to perform a first reaction, and obtaining amino-functionalized nano-silica represented by formula (3);

[0055]

[0056] S2, performing a second reaction of the amino-functionalized nano-silica with an acid anhydride compound in the presence of a second solvent, and obtaining carboxyl-functionalized nano-silica represented by formula (4);

[0057]

[0058] S3, in the presence of the basic catalyst, mixing the carboxyl-functionalized nano-silica with a condensation agent, activating, then adding a polyamino compound for a third reaction, to obtain modified nano-silica.

[0059] In the present application, the method is simple to operate, raw materials are easy to obtain, and the yield is high. The modified nano-silica product is a solid, non-flammable and explosive substance, and has good storage and transportation safety.

[0060] In the present application, the protective gas is nitrogen and / or inert gas.

[0061] In the present application, the steps S1, S2 and S3 each independently comprise a separation, washing and drying step.

[0062] Further, the separation method is not particularly limited, for example, it can be at least one of filtration, rotary evaporation or centrifugal separation.

[0063] Further, the conditions for washing are not particularly limited, for example, it can be washed 3-4 times with a solvent commonly used in the art, wherein the solvent can be at least one of methanol, ethanol and acetone. Preferably, in the step S1, acetone and dichloromethane are used for washing.

[0064] In the present application, in the step S1, acetone and dichloromethane are preferably used for washing, which can better wash and remove unreacted aminosilane, thereby improving the purity of the product.

[0065] According to the present application, in the step S1, the mass ratio of the nano-silica particles M to the aminosilane is 5-100:1.

[0066] In the present application, when the mass ratio of the nano-silica particles M to the aminosilane meets the above range, the amino content is more appropriate, further improving the crosslinking speed and crosslinking density of the epoxy resin containing the modified nano-silica.

[0067] Further, the mass ratio of the nano-silica particles M to the aminosilane is 10-50:1.

[0068] According to the present application, the aminosilane is selected from at least one of aminopropyltriethoxysilane, aminopropyltrimethoxysilane, aminopropylmethyldimethoxysilane and aminopropylmethyldiethoxysilane.

[0069] According to the present application, the conditions for the first reaction include a reaction temperature of 120-160℃ and a reaction time of 2-24h.

[0070] Further, the first reaction condition includes: the reaction temperature is 120-140℃, and the reaction time is 8-16h.

[0071] According to the present application, in step S2, the mass ratio of the amino-functionalized nanosilica to the acid anhydride compound is 5-100:1.

[0072] Further, the mass ratio of the amino-functionalized nanosilica to the acid anhydride compound is 10-50:1.

[0073] According to the present application, the acid anhydride compound is selected from at least one of maleic anhydride, phthalic anhydride and succinic anhydride.

[0074] According to the present application, the second reaction condition includes: the reaction temperature is 90-160℃, and the reaction time is 2-12h.

[0075] Further, the second reaction condition includes: the reaction temperature is 90-120℃, and the reaction time is 6-12h.

[0076] According to the present application, the first solvent and the second solvent are each independently selected from at least one of toluene, xylene, benzene and N,N-dimethylformamide.

[0077] According to the present application, in step S3, the mass ratio of the carboxyl-functionalized nanosilica, the condensing agent, the basic catalyst and the polyamino compound is 1:0.05-0.5:0.01-0.1:0.1-5.

[0078] In the present application, when the mass ratio of the carboxyl-functionalized nanosilica, the condensing agent, the basic catalyst and the polyamino compound meets the above-mentioned preferred range, the obtained modified nanosilica has the best comprehensive performance, and further improves the curing performance on the epoxy resin.

[0079] Further, the mass ratio of the carboxyl-functionalized nanosilica, the condensing agent, the basic catalyst and the polyamino compound is 1:0.05-0.3:0.01-0.05:0.1-4.

[0080] According to the present application, the condensing agent is selected from one of dicyclohexyl carbodiimide, diisopropyl carbodiimide and 1-(3-dimethylaminopropyl)-3-ethyl carbodiimide.

[0081] According to the present application, the basic catalyst is selected from at least one of 4-dimethylaminopyridine, 1,8-diazabicycloundec-7-ene and triethylamine.

[0082] According to the present application, the third reaction is carried out at a temperature of 0-40℃ for 2-48 hours.

[0083] Further, the third reaction is carried out at a temperature of 10-25℃ for 8-16 hours.

[0084] According to the present application, the activation in step S3 is carried out at a temperature of 10-25℃ for 8-24 hours.

[0085] According to a particularly preferred embodiment of the present application, the modified nanosilica is prepared according to the following steps, wherein x is 3, m is 3, and n is 0:

[0086] 1. Preparation of amino-functionalized nanosilica:

[0087]

[0088] 2. Preparation of carboxyl-functionalized nanosilica:

[0089]

[0090] 3. Preparation of modified nanosilica:

[0091]

[0092] The present application provides a modified nanosilica prepared by the above method.

[0093] The present application provides an application of the above modified nanosilica as a curing agent in epoxy resin.

[0094] In the present application, the modified nanosilica has a small particle size, and the binding force formed by the combination of the modified nanosilica and the epoxy groups in the epoxy resin is much greater than the van der Waals force, thus forming a more perfect interface, which can induce the generation of more micro-cracks, consume and absorb more energy, and also make the cracks encounter the obstruction and passivation of the modified nanosilica when expanding in the resin system, thus enhancing the effect of the epoxy resin system.

[0095] Further, the modified nanosilica has a small particle size and good dispersibility in the epoxy resin, and can migrate well to the surface of the epoxy resin during the curing process, thus increasing the roughness of the cured epoxy resin surface, and thus making the epoxy resin firmly adhere to the surface of the substrate.

[0096] Further, the active groups on the surface of the modified nanosilica, such as hydroxyl or carboxyl groups, can bond with the epoxy groups in the epoxy resin through a bonding reaction, thus improving the mechanical strength of the cured epoxy resin.

[0097] The fifth aspect of the present application provides an epoxy resin composition, characterized in that the epoxy resin composition comprises a curing agent component and a resin component;

[0098] The curing agent component contains the modified nanosilica according to the first aspect or the third aspect;

[0099] The resin component comprises an epoxy resin.

[0100] The curing agent component and the resin component are each independently present.

[0101] In the present application, the content of the modified nanosilica is 20-80 parts by weight based on 100 parts by weight of the epoxy resin.

[0102] In the present application, the epoxy resin composition can further contain emulsifiers, reinforcing agents and the like commonly used in the art, and there is no particular limitation on the types and amounts of the emulsifiers and reinforcing agents, which can be the types and amounts commonly used in the art.

[0103] The sixth aspect of the present application provides a cured epoxy resin, characterized in that the cured epoxy resin is prepared from the epoxy resin composition according to the fifth aspect of the present application.

[0104] In the present application, the compressive strength of the cured epoxy resin is not less than 28 MPa, and the glass transition temperature is not less than 120℃.

[0105] The present application will be described in detail below through examples. In the following examples,

[0106] The morphology parameters of the modified nanosilica are measured by transmission electron microscopy (TEM) and scanning electron microscopy (SEM);

[0107] The dispersion coefficient (PDI) of the modified nanosilica is measured by a laser particle size analyzer (DLS);

[0108] The amino content in the modified nanosilica is obtained by acid-base titration test;

[0109] Nanosilica particles M were purchased from Macklin Reagent;

[0110] Aminopropyl triethoxysilane was purchased from Macklin Reagent;

[0111] Maleic anhydride was purchased from Macklin Reagent;

[0112] Dicyclohexyl carbodiimide (DCC) was purchased from Macklin Reagent;

[0113] Diisopropyl carbodiimide (DIC) was purchased from Macklin Reagent;

[0114] 1,8-diazabicycloundec-7-ene (DBU) was purchased from Macklin Reagent;

[0115] 4-dimethylaminopyridine (DMAP) was purchased from Macklin Reagent;

[0116] tetraethylenepentamine was purchased from Macklin Reagent;

[0117] polyethyleneimine with molecular weight of 1500 was purchased from Macklin Reagent;

[0118] Other reagents were commercially available.

[0119] Example 1

[0120] S1, Preparation of amino-propyl functionalized nano-silica:

[0121] 2 g of nano-silica particles M with an average particle size of 30 nm and a specific surface area of 200 m 2 / g were weighed into 100 mL of anhydrous toluene, then 0.2 g of aminopropyl triethoxysilane was added, and the mixture was stirred under reflux at 150°C for 24 hours under nitrogen protection. After the reaction was completed, the solid product was obtained by centrifugation, and the obtained solid product was repeatedly washed with acetone and dichloromethane for 3 times, and then vacuum dried at 40°C for 12 h to obtain the amino-propyl functionalized nano-silica.

[0122] S2, Preparation of carboxyl functionalized nano-silica:

[0123] 2 g of the above-prepared amino-propyl functionalized nano-silica was weighed into 50 mL of toluene, then 0.2 g of maleic anhydride was added, and the mixture was stirred under reflux at 160°C for 6 hours under nitrogen protection. After the reaction was completed, the mixture was repeatedly washed with methanol for 3 times, and then vacuum dried at 40°C for 12 h to obtain the carboxyl functionalized nano-silica.

[0124] S3, Preparation of modified nano-silica:

[0125] 1 g of the above-prepared carboxyl functionalized nano-silica was weighed into 50 mL of toluene, then 0.25 g of diisopropyl carbodiimide (DIC) and 0.06 g of 1,8-diazabicycloundec-7-ene (DBU) were added, and the mixture was stirred at room temperature (25°C) for 1 hour to activate, then 4 g of polyethyleneimine (number average molecular weight of 1500) was added, and the mixture was continuously stirred at room temperature for 12 hours. After the reaction was completed, the mixture was repeatedly washed with methanol for 3 times, and then vacuum dried at 40°C for 12 h to obtain the modified nano-silica A1 with the structure of formula (1), wherein n is 0, m is 3, and x is 3.

[0126] The particle size of the modified nano-silica A1 was 30 nm, and the specific surface area was 300 m 2 / g, with an amino content of 2mmol / g.

[0127] like Figure 1 As shown, the prepared modified nano-silica Al is dispersed relatively uniformly in water and has good dispersibility; Figure 2 and Figure 3 These are transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images of high-density amino-modified nano-silica. Figures 2-3 It can be seen that the high-density amino-modified nano-silica particles are relatively uniform. The modified nano-silica Al was tested using a laser particle size analyzer, and its dispersion index (PDI) was 0.11.

[0128] Example 2

[0129] S1. Preparation of aminopropyl-functionalized nano-silica:

[0130] 5g of particles with an average diameter of 200nm and a specific surface area of ​​50m² 2 / g of nano-silica particles M were dispersed in 100mL of anhydrous toluene, and then 0.5g of aminopropyltriethoxysilane was added. The mixture was refluxed and stirred at 120℃ for 24 hours under nitrogen protection. After the reaction was completed, the solid product was obtained by centrifugation. The solid product was washed three times with acetone and dichloromethane and then dried under vacuum at 40℃ for 12 hours to obtain aminopropyl-functionalized nano-silica.

[0131] S2, Preparation of carboxyl-functionalized nano-silica:

[0132] Weigh 2g of the above-prepared aminopropyl-functionalized nano-silica and disperse it in 50mL of xylene. Add 0.2g of maleic anhydride and reflux at 140℃ for 6 hours under nitrogen protection. After the reaction is complete, wash the nano-silica repeatedly with methanol 3 times and dry it under vacuum at 40℃ for 12 hours to obtain carboxyl-functionalized nano-silica.

[0133] S3. Preparation of modified nano-silica:

[0134] Weigh 2g of the carboxyl-functionalized nano silica prepared above, disperse it in 50mL of toluene, then add 0.15g of dicyclohexylcarbodiimide (DCC) and 0.03g of 4-dimethylaminopyridine (DMAP), stir and activate at room temperature for 0.5 hours, then add 0.6g of tetraethylenepentamine (p=3), and continue to react at room temperature for 12 hours. After the reaction is completed, wash repeatedly with methanol 3 times, and vacuum dry at 40℃ for 12 hours to obtain modified nano silica A2 with the structure of formula (1), where n=0, m=3, and x=3.

[0135] The modified nano-silica A2 has a particle size of 200 nm and a specific surface area of ​​100 m². 2 / g, with an amino content of 0.2mmol / g.

[0136] like Figure 4 As shown, the prepared modified nano-silica A2 is dispersed relatively uniformly in water and has good dispersibility; Figure 5 and Figure 6 These are transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images of high-density amino-modified nano-silica. Figures 5-6 It can be seen that the high-density amino-modified nano silica particles are relatively uniform. The modified nano silica A2 was tested with a laser particle size analyzer and its dispersion coefficient (PDI) was 0.13.

[0137] Example 3

[0138] The method is consistent with that used in Example 1, except that the specific surface area of ​​the nano-silica particles M is 100 m². 2 / g, and in step S3, the amount of polyethyleneimine (molecular weight of 1500) used is 0.4g;

[0139] The modified nano-silica A3 has a particle size of 30 nm and a specific surface area of ​​230 m². 2 / g, with an amino content of 0.1mmol / g.

[0140] The final test result for A3 showed a dispersion factor (PDI) of 0.13.

[0141] Example 4

[0142] The method is the same as that used in Example 1, except that in step S3, the amount of polyethyleneimine used is 0.04 g.

[0143] The modified nano-silica A4 has a particle size of 30 nm and a specific surface area of ​​300 m². 2 / g, with an amino content of 0.05mmol / g.

[0144] The final test result for A4 showed a dispersion factor (PDI) of 0.12.

[0145] Example 5

[0146] The method is the same as that used in Example 1, except that in step S1, aminopropyltriethoxysilane is replaced with aminopropyltrimethoxysilane.

[0147] The modified nano-silica A5 has a particle size of 30 nm and a specific surface area of ​​300 m². 2 / g, with an amino content of 2mmol / g.

[0148] The final test result for A5 showed a dispersion factor (PDI) of 0.14.

[0149] Example 6

[0150] The method is consistent with that of Preparation Example 1, except that in step S1, the average particle size of the nanosilica is 800 nm, and the specific surface area is 5 m 2 / g;

[0151] The modified nanosilica A6 finally prepared has a particle size of 800 nm, a specific surface area of 50 m 2 / g, and an amino content of 0.02 mmol / g.

[0152] The dispersion coefficient PDI of A6 finally tested is 0.13.

[0153] Example 7

[0154] The method is consistent with that of Preparation Example 1, except that in step S3, the amount of polyethyleneimine (molecular weight of 3000) is 0.01 g;

[0155] The modified nanosilica A7 has a particle size of 30 nm, a specific surface area of 400 m 2 / g, and an amino content of 0.01 mmol / g.

[0156] The dispersion coefficient PDI of A7 finally tested is 0.13.

[0157] Example 8

[0158] The method is consistent with that of Preparation Example 1, except that in step S2, the amount of maleic anhydride is 0.02 g;

[0159] The modified nanosilica A8 finally obtained has a particle size of 30 nm, a specific surface area of 250 m 2 / g, and an amino content of 0.015 mmol / g.

[0160] The dispersion coefficient PDI of A8 finally tested is 0.14.

[0161] Example 9

[0162] The method is consistent with that of Preparation Example 1, except that in step S1, the amount of aminopropyltriethoxysilane is 0.033 g;

[0163] The modified nanosilica A9 finally obtained has a particle size of 30 nm, a specific surface area of 280 m 2 / g, and an amino content of 0.4 mmol / g.

[0164] The dispersion coefficient PDI of A9 finally tested is 0.14.

[0165] Example 10

[0166] The method of Preparation Example 1 is consistent, except that in step S1, aminopropyltrimethoxysilane is replaced by aminopropylmethyldiethoxysilane;

[0167] The particle size of the modified nanosilica A9 finally obtained is 30 nm, the specific surface area is 280 m 2 / g, the amino content is 0.4 mmol / g. Wherein n is 1, m is 2, and x is 3.

[0168] The dispersion coefficient PDI of A9 finally tested is 0.13.

[0169] Comparative Example 1

[0170] S1, 1g of dimethylphenylsilane is weighed and dispersed in 50mL of xylene, 0.098g of maleic anhydride is added, and the reaction is stirred under reflux at 160℃ for 6 hours under nitrogen protection. After the reaction is completed, it is repeatedly washed with methanol for 3 times, and vacuum dried at 40℃ for 12h to obtain a carboxyl functionalized organosilicon.

[0171] S2, 2g of the above carboxyl functionalized organosilicon is weighed and dispersed in 50mL of toluene, 0.051g of diisopropyl carbodiimide (DIC) and 0.122g of 1,8-diazabicycloundec-7-ene (DBU) are added, and the mixture is stirred at room temperature (25℃) for 1 hour. Then 0.45g of polyethyleneimine (molecular weight of 1500) is added, and the reaction is continued at room temperature for 12 hours. After the reaction is completed, it is repeatedly washed with methanol for 3 times, and vacuum dried at 40℃ for 12h to obtain a modified organosilicon D1.

[0172] The particle size of the modified organosilicon D2 is 30nm, the specific surface area is 300m 2 / g, the amino content is 2mmol / g.

[0173] The dispersion coefficient PDI of D1 finally tested is 0.45.

[0174] Comparative Example 2

[0175] The method of Preparation Example 1 is consistent, except that the multi-amino modification of step S3 is not performed, and a carboxyl functionalized nanosilica D2 is finally obtained.

[0176] The particle size of the carboxyl functionalized nanosilica D2 is 30nm, the specific surface area is 100m 2 / g, the amino content is 0mmol / g.

[0177] The dispersion coefficient PDI of D2 finally tested is 0.13.

[0178] Test Example

[0179] The modified nanosilica obtained from the examples and comparative examples is applied to the epoxy resin as a curing agent, and the curing performance of the epoxy resin is tested. The epoxy resin used in the experiment is E51, which is purchased from Balin Petrochemical.

[0180] Specifically, 100g of epoxy resin and 30g of the material prepared by A1-A10 and D1-D2 are mixed and cured at a curing temperature of 130 DEG C for 2h to obtain the cured epoxy resin E1-E10 and DE1-DE2. The compressive strength and glass transition temperature of the cured epoxy resin E1-E10 and DE1-DE2 are tested.

[0181] The compressive strength is tested by a 5969 type high-low temperature universal material testing machine;

[0182] The glass transition temperature is tested by a DSC method.

[0183] The test results are shown in the following table:

[0184] Table 1

[0185]

[0186]

[0187] The above results show that the modified nanosilica provided by the application as a curing agent for the epoxy resin has good effects, and the cured epoxy resin E1-E10 has a compressive strength of not less than 28MPa and a glass transition temperature of not less than 120 DEG C.

[0188] Further, the preferred embodiments 1-2 and 5 are further satisfied, and the cured epoxy resin E1-E2 and E5 prepared thereby has better technical effects, specifically, the compressive strength is not less than 48MPa, and the glass transition temperature is not less than 135 DEG C.

[0189] The above describes the preferred embodiments of the application, but the application is not limited thereto. Within the technical concept of the application, various simple modifications can be made to the technical solutions of the application, including the combination of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as disclosed by the application, and are within the protection scope of the application.

Claims

1. A modified nanosilica characterized in that, The modified nano-silica has a structure shown in formula (1): Formula (1) Wherein, M is a nano-silica particle, x is an integer of 1-4, and R is an alkyl group with a carbon atom number of 1-4; n is an integer of 0-3, m is an integer of 1-3, and n+m=3; A is a structural unit from an anhydride compound, and B is a structural unit from a polyamino compound; The polyamino compound is a linear polyethylene polyamino compound with a structure shown in formula (2) or a non-linear polyethylene imine with a number average molecular weight of 300-3000: Formula (2) Wherein, p is an integer of 1-6.

2. The modified nanosilica of claim 1, wherein, The anhydride compound is selected from at least one of maleic anhydride, phthalic anhydride and succinic anhydride.

3. The modified nanosilica of claim 1 or 2, wherein, The nano-silica particles M have a particle size of 10-500 nm and a specific surface area of 10-300 m 2 / g; And / or, the amino content of the modified nano-silica is 0.1-5 mmol / g.

4. The modified nanosilica of claim 1 or 2, wherein, The modified nano-silica has a particle size of 10-500 nm, a specific surface area of 50-300 m 2 / g.

5. A method of producing the modified nanosilica according to any one of claims 1 to 4, characterized in that, The method comprises the following steps: S1, dispersing the nano-silica particle M in a first solvent in the presence of a protective gas, adding an amino silane to perform a first reaction to obtain an amino-functionalized nano-silica shown in formula (3); Formula (3) S2, in the presence of a second solvent, the amino-functionalized nano-silica is reacted with an anhydride compound to obtain a carboxyl-functionalized nano-silica shown in formula (4); Equation (4) S3, in the presence of a basic catalyst, the carboxyl-functionalized nano-silica is mixed with a condensing agent, activated, and then a polyamino compound is added to perform a third reaction to obtain a modified nano-silica.

6. The method of claim 5, wherein, In step S1, the mass ratio of the nano-silica particle M to the amino silane is 5-100:1; And / or, the amino silane is selected from at least one of aminopropyl triethoxysilane, aminopropyl trimethoxysilane, aminopropyl methyl dimethoxysilane and aminopropyl methyl diethoxysilane; And / or, the conditions of the first reaction include: the reaction temperature is 120-160℃, and the reaction time is 2-24h; And / or, in step S2, the mass ratio of the amino-functionalized nano-silica to the anhydride compound is 5-100:1; And / or, the conditions of the second reaction include: the reaction temperature is 90-160℃, and the reaction time is 2-12h; And / or, the first solvent and the second solvent are each independently selected from at least one of toluene, xylene, benzene and N,N-dimethylformamide.

7. The method of claim 5 or 6, wherein, In step S3, the mass ratio of the carboxyl-functionalized nano-silica, the condensing agent, the basic catalyst and the polyamino compound is 1:0.05-0.5:0.01-0.1:0.1-5; And / or, the conditions of the third reaction include: the reaction temperature is 0-40℃, and the reaction time is 2-48h; And / or, the activation conditions include: the activation temperature is 10-25℃, and the activation time is 8-24h.

8. The method of claim 7, wherein, The condensing agent is selected from one of dicyclohexyl carbodiimide, diisopropyl carbodiimide and 1-(3-dimethylaminopropyl)-3-ethyl carbodiimide; And / or, the basic catalyst is selected from at least one of 4-dimethylamino pyridine, 1,8-diazabicyclo[5.4.0]undec-7-ene and triethylamine.

9. Modified nanosilica prepared by the method of any one of claims 5-8.

10. Use of the modified nanosilica of any one of claims 1-4 and 9 as a curing agent in an epoxy resin.

11. An epoxy resin composition, characterized by comprising: The epoxy resin composition comprises a curing agent component and a resin component; The curing agent component contains the modified nanosilica of any one of claims 1-4 and 9; The resin component includes an epoxy resin; The curing agent component and the resin component are each independently present.

12. A cured epoxy resin, characterized by, The cured epoxy resin is prepared from the epoxy resin composition of claim 11.

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