CN114891269A - Ultraviolet aging resistant silicone rubber and preparation method thereof - Google Patents
Ultraviolet aging resistant silicone rubber and preparation method thereof Download PDFInfo
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Abstract
The invention relates to ultraviolet aging resistant silicone rubber and a preparation method thereof. Solves the technical problems that the nano titanium dioxide used for preventing the ultraviolet aging of the silicon rubber in the prior art has poor compatibility with the silicon rubber, and is easy to agglomerate in the silicon rubber base rubber to cause the deterioration of material performance, thus having no function of application. The liquid spherical titanium dioxide nano particle consists of a spherical titanium dioxide nano particle and a polysilazane grafted chain grafted on the surface of the spherical titanium dioxide nano particleThe amino group surface density is 7.3 to 30nmol/cm 2 The structural formula of the polysilazane grafted chain is shown as a formula I, wherein n is an integer of 2-10. When the liquid spherical titanium dioxide nano particles are mixed with the crude silicone rubber, the nano particles are uniformly dispersed singly, so that the damage of ultraviolet rays to the performance of the silicone rubber can be effectively reduced, and the ultraviolet aging resistance of the silicone rubber can be effectively improved.
Description
Technical Field
The invention belongs to the technical field of silicone rubber, and particularly relates to ultraviolet aging resistant silicone rubber and a preparation method thereof.
Background
The silicone rubber is an elastomer material which is formed by linear polysiloxane after cross-linking reaction and has a three-dimensional network structure, and has a unique organic-inorganic hybrid molecular chain structure. According to different vulcanization mechanisms, silicone rubber can be divided into three types: room temperature vulcanization type, heat vulcanization type, and addition reaction type. The addition reaction type silicon rubber can be used for a long time in the temperature range of-65-200 ℃, can keep the soft elastic performance, has excellent electrical performance and chemical stability, simultaneously has weather resistance, water resistance and ozone resistance, has the remarkable characteristics of no toxicity, no odor, no corrosion, physiological inertia, low linear shrinkage rate, easy operation and the like, and is widely applied to the fields of military affairs, buildings, medical treatment, automobiles, aerospace, daily chemicals, articles for daily use and the like.
However, when the silicone rubber is exposed outdoors for a long time or in the place containing ultraviolet rays, crosslinking reaction can occur on the surface of the silicone rubber material, even leading to the breakage of molecular chains of the material and the destruction of molecular structures, thereby causing the deterioration or even complete loss of the service performance of the material.
To prevent or slow down uv aging of silicone rubber materials, the addition of uv screeners to the polymer matrix is the most traditional and most widely used method. Among them, inorganic uv-screening agents have the advantages of better economic benefit, lower toxicity and higher uv-screening efficiency, and begin to become hot spots for uv-protection research and application, and the inorganic uv-screening agents commonly used at present include zinc oxide and titanium dioxide (TiO) 2 ) And iron oxide and the like.
Among them, nano titanium dioxide is an important inorganic ultraviolet screening agent, has good weather resistance and heat resistance, and can be used for improving the light stability of outdoor products. In addition, the nano titanium dioxide has smaller particle size, a plurality of atoms on the surface of the particle, and high surface energy and activity, and can improve the properties of hardness, rigidity and the like of the polymer material by improving the binding force between the nano titanium dioxide and the polymer, thereby finally playing a certain role in strengthening and toughening. However, because the nano titanium dioxide contains Ti-O bonds with large polarity, the nano titanium dioxide is easy to be subjected to water dissociation on the surface of a polymer material to form a large number of hydroxyl groups, and compared with the characteristics of hydrophile lipophobicity and polarity of the nano titanium dioxide, the silicon rubber is just opposite to hydrophobic and nonpolar, so the dispersibility of the nano titanium dioxide in a silicon rubber matrix is generally poor. Meanwhile, the specific surface area of the nano titanium dioxide is much larger than that of common particles, the specific surface energy is very high and is in a thermodynamically unstable state, and the nano titanium dioxide on the surface always tends to lean against each other under the action of intermolecular van der Waals force and coulomb force, so that the nano titanium dioxide is finally agglomerated with each other, the dispersibility in the silicon rubber is poor, stress concentration is easy to occur during stress, and the mechanical property of the silicon rubber is seriously influenced.
Disclosure of Invention
The invention provides ultraviolet aging resistant silicone rubber and a preparation method thereof, aiming at solving the technical problems that in the prior art, nano titanium dioxide for preventing silicone rubber from ultraviolet aging has poor compatibility with silicone rubber, and is easy to agglomerate in silicone rubber-based rubber to cause material performance deterioration and cannot play a role in application.
The technical scheme adopted by the invention for solving the technical problems is as follows.
The invention provides a polysilazane-modified spherical titanium dioxide nanoparticle, which consists of a spherical titanium dioxide nanoparticle and a polysilazane grafted chain grafted on the surface of the spherical titanium dioxide nanoparticle;
the structural formula of the polysilazane grafted chain is as follows:
in the formula, n is an integer of 2-10;
the amino surface density of the polysilazane-modified spherical titanium dioxide nanoparticles is 7.3-30 nmol/cm 2 。
The invention also provides a preparation method of the polysilazane-modified spherical titanium dioxide nanoparticles, which comprises the following steps:
1) corroding the spherical titanium dioxide nano particles with weak acid, washing with water, and drying to obtain acid-treated spherical titanium dioxide nano particles;
2) reacting the spherical titanium dioxide nano particles subjected to acid treatment with terminal aminosilane in an organic solvent, carrying out reduced pressure distillation to remove the organic solvent, and drying to obtain spherical titanium dioxide nano particles subjected to terminal aminosilane treatment;
the structural formula of the terminal aminosilane is as follows:
in the formula, n is an integer of 2-10;
3) mixing the spherical titanium dioxide nano particles treated by the amino silane and R obtained in the step 2) 2 SiX 2 Reacting in an organic solvent, removing the organic solvent, and drying to obtain polysilazane-modified spherical titanium dioxide nanoparticles;
the R is 2 SiX 2 In, R 2 Is CH 3 Or Ph and X are chlorine or bromine.
Preferably, in the step 1), the weak acid is selected from one or more of hydrofluoric acid, oxalic acid and maleic acid; the concentration of the weak acid is 10-35 wt%.
Preferably, in the step 1), the ratio of the spherical titanium dioxide nanoparticles to the weak acid is 1 g: (10-100) ml.
Preferably, in the step 2), the organic solvent is toluene, and the reaction time is 4 h.
Preferably, in the step 2), the mass ratio of the spherical titanium dioxide nanoparticles after acid treatment to the terminal aminosilane is 1: 100.
Preferably, in the step 3), the organic solvent is acetone.
Preferably, in the step 3), the reaction temperature is 50 ℃ and the reaction time is 6 h.
Preferably, in the step 3), the amino silane-terminated spherical titanium dioxide nanoparticles are reacted with R 2 SiX 2 The mass ratio of (A) to (B) is 1: 1.
The invention also provides ultraviolet aging resistant silicone rubber which comprises the component A and the component B in a mass ratio of 50: 50;
the component A is prepared by uniformly mixing 20-80 parts by weight of polysilazane-modified spherical titanium dioxide nanoparticles, 30-80 parts by weight of terminal ethoxy high phenyl vinyl silicone polymer and 20-30 parts by weight of methyl vinyl silicone oil, and the component B is prepared by uniformly mixing 20-80 parts by weight of Pt and 10-20 parts by weight of hydrogen-containing silicone oil;
the structural formula of the end ethoxy high phenyl vinyl organosilicon polymer is as follows:
the average molecular weight of the terminal ethoxy high phenyl vinyl organosilicon polymer is 11000-61000.
Preferably, the component A is prepared by uniformly mixing 30-80 parts by weight of polysilazane-modified spherical titanium dioxide nanoparticles, 40-50 parts by weight of terminal ethoxy high phenyl vinyl silicone polymer and 20 parts by weight of methyl vinyl silicone oil, and the component B is prepared by uniformly mixing 20-50 parts by weight of Pt and 10-20 parts by weight of hydrogen-containing silicone oil.
The invention also provides a preparation method of the ultraviolet aging resistant silicone rubber, which comprises the following steps:
weighing the component A and the component B according to the proportion, uniformly mixing, placing in a mold, pressurizing, heating and vulcanizing to obtain the ultraviolet aging resistant silicone rubber.
Preferably, a three-roll mill is used to mix the component A and the component B uniformly.
Preferably, the vulcanization temperature is 160 +/-10 ℃, the vulcanization pressure is 5-10 MPa, and the vulcanization time is 20-30 min.
Compared with the prior art, the invention has the beneficial effects that:
the polysilazane modified spherical titanium dioxide nano particle realizes liquidization by controlling the length of the grafting chain and the grafting surface density, thereby ensuring that the nano particle is singly and uniformly dispersed when being mixed with raw silicone rubber, effectively reducing the damage of ultraviolet rays to the performance of the silicone rubber and effectively improving the ultraviolet aging resistance of the silicone rubber.
The spherical titanium dioxide nanoparticles modified by polysilazane are in a liquid state at room temperature, can be uniformly mixed with raw silicone rubber, can furthest play the role of the titanium dioxide nanoparticles in preventing ultraviolet aging of the silicone rubber, and can improve the humidity and heat aging resistance of the silicone rubber to a certain extent due to the existence of the polysilazane structure. Before ultraviolet aging, the tensile strength at room temperature of the ultraviolet aging resistant silicon rubber is as follows: 6.2-7.0 Mpa; shore a hardness after 14 days: 50-65 parts; elongation at break: 370-400%; room temperature tensile strength after uv aging: 4.9-6.3 Mpa; shore a hardness after 14 days: 38-52; elongation at break: 550-610%.
Detailed Description
For a further understanding of the invention, reference will now be made to the preferred embodiments of the invention, but it is to be understood that the description is intended to illustrate further features and advantages of the invention, and not to limit the scope of the claims.
The polysilazane-modified spherical titanium dioxide nanoparticles are composed of spherical titanium dioxide nanoparticles and polysilazane grafted chains grafted on the surfaces of the spherical titanium dioxide nanoparticles;
wherein the structural formula of the polysilazane grafted chain is as follows:
in the formula, n is an integer of 2-10;
the amino surface density of the polysilazane-modified spherical titanium dioxide nanoparticles is 7.3-30 nmol/cm 2 。
The polysilazane modified spherical titanium dioxide nano particle realizes liquidization by controlling the length of the grafting chain and the grafting surface density, thereby ensuring that the nano particle is singly and uniformly dispersed when being mixed with raw silicone rubber, effectively reducing the damage of ultraviolet rays to the performance of the silicone rubber and effectively improving the ultraviolet aging resistance of the silicone rubber.
The preparation method of the polysilazane modified spherical titanium dioxide nano particle comprises the following steps:
1) corroding the spherical titanium dioxide nano particles with weak acid, washing with water, and drying to obtain acid-treated spherical titanium dioxide nano particles;
2) reacting the spherical titanium dioxide nano particles subjected to acid treatment with terminal aminosilane in an organic solvent, carrying out reduced pressure distillation to remove the organic solvent, and drying to obtain spherical titanium dioxide nano particles subjected to terminal aminosilane treatment;
wherein the structural formula of the terminal aminosilane is as follows:
in the formula, n is an integer of 2-10;
3) treating the spherical titanium dioxide nano particles treated by the amino silane terminated obtained in the step 2)And R 2 SiX 2 Reacting in an organic solvent, removing the organic solvent, and drying to obtain polysilazane-modified spherical titanium dioxide nanoparticles;
wherein R is 2 SiX 2 In, R 2 Is CH 3 Or Ph and X are chlorine or bromine.
In the above technical solution, in the step 1), the weak acid is preferably selected from one or more of hydrofluoric acid, oxalic acid and maleic acid; the concentration of the weak acid is preferably 10-35 wt%; more preferably 15 to 20 wt% of hydrofluoric acid.
In the above technical scheme, in the step 1), the time of weak acid corrosion is preferably 24 hours.
In the above technical scheme, in step 1), the ratio of the spherical titanium dioxide nanoparticles to the weak acid is preferably 1 g: (10-100) ml.
In the above technical scheme, in the step 2), the organic solvent is toluene, and the reaction time is 4 h.
In the technical scheme, in the step 2), the mass ratio of the spherical titanium dioxide nano particles subjected to acid treatment to the terminal aminosilane is 1: 100.
In the above technical solution, in the step 3), the organic solvent is not particularly limited, and is preferably acetone.
In the above technical scheme, in the step 3), the reaction temperature is preferably 50 ℃, and the reaction time is preferably 6 h.
In the above technical scheme, in step 3), the spherical titanium dioxide nanoparticles treated by the terminal aminosilane and R 2 SiX 2 The mass ratio of (A) to (B) is 1: 1.
The synthetic route of the polysilazane-modified spherical titanium dioxide nanoparticles of the invention is as follows:
wherein, the mil acid represents weak acid.
The ultraviolet aging resistant silicone rubber comprises a component A and a component B in a mass ratio of 50: 50;
the component A is formed by uniformly mixing 20-80 parts by weight of polysilazane-modified spherical titanium dioxide nanoparticles, 30-80 parts by weight of terminal ethoxy high phenyl vinyl silicone polymer and 20-30 parts by weight of methyl vinyl silicone oil, and the component B is formed by uniformly mixing 20-80 parts by weight of Pt and 10-20 parts by weight of hydrogen-containing silicone oil;
wherein, the structural formula of the end ethoxy high phenyl vinyl organosilicon polymer is as follows:
the average molecular weight of the ethoxy-terminated high phenyl vinyl organosilicon polymer is 11000-61000.
The synthesis route of the terminal ethoxy high phenyl vinyl organosilicon polymer is as follows:
according to the invention, preferably, the component A is prepared by uniformly mixing 30-80 parts by weight of polysilazane-modified spherical titanium dioxide nanoparticles, 40-50 parts by weight of terminal ethoxy high phenyl vinyl silicone polymer and 20 parts by weight of methyl vinyl silicone oil, and the component B is prepared by uniformly mixing 20-50 parts by weight of Pt and 10-20 parts by weight of hydrogen-containing silicone oil. More preferably, the component A is formed by uniformly mixing 30 parts of polysilazane-modified spherical titanium dioxide nanoparticles, 40 parts of terminal ethoxy high phenyl vinyl silicone polymer and 20 parts of methyl vinyl silicone oil, and the component B is formed by uniformly mixing 30 parts of Pt and 10 parts of hydrogen-containing silicone oil; or the component A is formed by uniformly mixing 40 parts of polysilazane-modified spherical titanium dioxide nano particles, 40 parts of terminal ethoxy high phenyl vinyl silicone polymer and 20 parts of methyl vinyl silicone oil, and the component B is formed by uniformly mixing 30 parts of Pt and 10 parts of hydrogen-containing silicone oil; or the component A is formed by uniformly mixing 50 parts of polysilazane-modified spherical titanium dioxide nano particles, 50 parts of terminal ethoxy high phenyl vinyl silicone polymer and 20 parts of methyl vinyl silicone oil, and the component B is formed by uniformly mixing 40 parts of Pt and 20 parts of hydrogen-containing silicone oil; or the component A is formed by uniformly mixing 70 parts of polysilazane-modified spherical titanium dioxide nano particles, 50 parts of terminal ethoxy high phenyl vinyl silicone polymer and 20 parts of methyl vinyl silicone oil, and the component B is formed by uniformly mixing 40 parts of Pt and 20 parts of hydrogen-containing silicone oil; or the component A is formed by uniformly mixing 80 parts of polysilazane-modified spherical titanium dioxide nano particles, 50 parts of terminal ethoxy high phenyl vinyl silicone polymer and 20 parts of methyl vinyl silicone oil, and the component B is formed by uniformly mixing 50 parts of Pt and 20 parts of hydrogen-containing silicone oil.
The invention also provides a preparation method of the ultraviolet aging resistant silicone rubber, which comprises the following steps:
weighing the component A and the component B according to the proportion, uniformly mixing, placing in a mold, pressurizing, heating and vulcanizing to obtain the ultraviolet aging resistant silicone rubber.
In the above technical scheme, a three-roll grinder is preferably used for uniformly mixing the component A and the component B.
In the technical scheme, the vulcanization temperature is preferably 160 +/-10 ℃, the vulcanization pressure is preferably 5-10 MPa, and the vulcanization time is preferably 20-30 min.
The spherical titanium dioxide nanoparticles modified by polysilazane are in a liquid state at room temperature, can be uniformly mixed with other types of silicon rubber, can furthest play the role of the titanium dioxide nanoparticles in preventing ultraviolet aging of the silicon rubber, and can improve the humidity and heat aging resistance of the silicon rubber to a certain extent due to the existence of the polysilazane structure.
Before ultraviolet aging, the tensile strength at room temperature of the ultraviolet aging resistant silicon rubber is as follows: 6.2-7.0 Mpa; shore a hardness after 14 days: 50-65 parts; elongation at break: 370-400%; room temperature tensile strength after uv aging: 4.9-6.3 Mpa; shore a hardness after 14 days: 38-52; elongation at break: 550-610%.
The terms used in the present invention generally have meanings commonly understood by those of ordinary skill in the art, unless otherwise specified. In order to make those skilled in the art better understand the technical solution of the present invention, the present invention will be further described in detail with reference to the following embodiments.
In the following examples, various procedures and methods not described in detail are conventional methods well known in the art. Materials, reagents, devices, instruments, apparatuses and the like used in the following examples are commercially available unless otherwise specified.
The present invention is further illustrated by the following examples.
Example 1
1) Preparation of polysilazane-modified spherical titanium dioxide nanoparticles
1a) Soaking spherical titanium dioxide nano particles in 15 wt% hydrofluoric acid for 24h, washing with water for three times, and drying to obtain acid-treated silicon dioxide nano particles;
1b) adding acid-treated spherical titanium dioxide nanoparticles and commercially available terminal aminosilane (n is 4) into toluene in a mass ratio of 1:100, uniformly stirring, reacting for 4 hours, distilling under reduced pressure to remove toluene, and drying to obtain titanium dioxide nanoparticles treated by the terminal aminosilane;
1c) uniformly mixing the titanium dioxide nano particles subjected to the amino silane termination treatment, diphenyl dichloro (bromo) silane and acetone according to the mass ratio of 1:1, heating to 50 ℃, reacting for 6 hours, and removing the acetone through reduced pressure distillation to obtain liquid polysilazane-modified spherical titanium dioxide nano particles.
2) Preparation of Silicone rubber
Taking the component A and the component B according to the mass ratio of 50:50, putting the component A and the component B into a three-roll grinder, uniformly mixing, putting the mixture into a mould, pressurizing at 160 +/-10 ℃ for 5-10 MPa, and vulcanizing for 20-30 min to obtain ultraviolet aging resistant silicon rubber (rubber sheet);
by weight: the component A is formed by uniformly mixing 30 parts of spherical nano particles modified by end polysiloxane (phenyl substitution), 40 parts of end ethoxy high phenyl vinyl organosilicon polymer and 20 parts of methyl vinyl silicone oil; the component B is formed by uniformly mixing 20 parts of Pt (main catalyst) and 10 parts of hydrogen-containing organic silicone oil (202 organic silicone oil).
Example 2
1) Preparation of polysilazane-modified spherical titanium dioxide nanoparticles
1a) Soaking spherical titanium dioxide nano particles in 15 wt% hydrofluoric acid for 24h, washing with water for three times, and drying to obtain acid-treated silicon dioxide nano particles;
1b) adding acid-treated spherical titanium dioxide nanoparticles and commercially available terminal aminosilane (n is 4) into toluene in a mass ratio of 1:100, uniformly stirring, reacting for 4 hours, distilling under reduced pressure to remove toluene, and drying to obtain titanium dioxide nanoparticles treated by the terminal aminosilane;
1c) uniformly mixing the titanium dioxide nano particles subjected to the amino silane termination treatment, diphenyl dichloro (bromo) silane and acetone according to the mass ratio of 1:1, heating to 50 ℃, reacting for 6 hours, and removing the acetone through reduced pressure distillation to obtain liquid polysilazane-modified spherical titanium dioxide nano particles.
2) Preparation of Silicone rubber
Taking the component A and the component B according to the mass ratio of 50:50, putting the component A and the component B into a three-roll grinder, uniformly mixing, putting the mixture into a mould, pressurizing at 160 +/-10 ℃ for 5-10 MPa, and vulcanizing for 20-30 min to obtain ultraviolet aging resistant silicon rubber (rubber sheet);
by weight: the component A is formed by uniformly mixing 40 parts of spherical nano particles modified by end polysiloxane (phenyl substitution), 40 parts of end ethoxy high phenyl vinyl organosilicon polymer and 20 parts of methyl vinyl silicone oil; the component B is formed by uniformly mixing 30 parts of Pt (main catalyst) and 10 parts of hydrogen-containing organic silicone oil (202 organic silicone oil).
Example 3
1) Preparation of polysilazane-modified spherical titanium dioxide nanoparticles
1a) Soaking spherical titanium dioxide nano particles in 15 wt% hydrofluoric acid for 24h, washing with water for three times, and drying to obtain acid-treated silicon dioxide nano particles;
1b) adding acid-treated spherical titanium dioxide nanoparticles and commercially available terminal aminosilane (n is 4) into toluene in a mass ratio of 1:100, uniformly stirring, reacting for 4 hours, distilling under reduced pressure to remove toluene, and drying to obtain titanium dioxide nanoparticles treated by the terminal aminosilane;
1c) uniformly mixing titanium dioxide nano particles treated by terminal amino silane, diphenyl (methyl) dichloro (bromo) silane and acetone according to the mass ratio of 1:1, heating to 50 ℃, reacting for 6 hours, and removing the acetone through reduced pressure distillation to obtain liquid polysilazane-modified spherical titanium dioxide nano particles.
2) Preparation of Silicone rubber
Taking the component A and the component B according to the mass ratio of 50:50, putting the component A and the component B into a three-roll grinder, uniformly mixing, putting the mixture into a mould, pressurizing at 160 +/-10 ℃ for 5-10 MPa, and vulcanizing for 20-30 min to obtain ultraviolet aging resistant silicon rubber (rubber sheet);
by weight: the component A is formed by uniformly mixing 50 parts of spherical nano particles modified by end polysiloxane (phenyl substitution), 50 parts of end ethoxy high phenyl vinyl organosilicon polymer and 20 parts of methyl vinyl silicone oil; the component B is prepared by uniformly mixing 40 parts of Pt (main catalyst) and 20 parts of hydrogen-containing organic silicone oil (202 organic silicone oil).
Example 4
1) Preparation of polysilazane-modified spherical titanium dioxide nanoparticles
1a) Soaking spherical titanium dioxide nano particles in 15 wt% hydrofluoric acid for 24h, washing with water for three times, and drying to obtain acid-treated silicon dioxide nano particles;
1b) adding acid-treated spherical titanium dioxide nanoparticles and commercially available terminal aminosilane (n is 4) into toluene in a mass ratio of 1:100, uniformly stirring, reacting for 4 hours, distilling under reduced pressure to remove toluene, and drying to obtain titanium dioxide nanoparticles treated by the terminal aminosilane;
1c) uniformly mixing the titanium dioxide nano particles subjected to the amino silane termination treatment, diphenyl dichloro (bromo) silane and acetone according to the mass ratio of 1:1, heating to 50 ℃, reacting for 6 hours, and removing the acetone through reduced pressure distillation to obtain liquid polysilazane-modified spherical titanium dioxide nano particles.
2) Preparation of Silicone rubber
Taking the component A and the component B according to the mass ratio of 50:50, putting the component A and the component B into a three-roll grinder, uniformly mixing, putting the mixture into a mould, pressurizing at 160 +/-10 ℃ for 5-10 MPa, and vulcanizing for 20-30 min to obtain ultraviolet aging resistant silicon rubber (rubber sheet);
by weight: the component A is formed by uniformly mixing 70 parts of spherical nano particles modified by end polysiloxane (phenyl substitution), 50 parts of end ethoxy high phenyl vinyl organosilicon polymer and 20 parts of methyl vinyl silicone oil; the component B is prepared by uniformly mixing 40 parts of Pt (main catalyst) and 20 parts of hydrogen-containing organic silicone oil (202 organic silicone oil).
Example 5
1) Preparation of polysilazane-modified spherical titanium dioxide nanoparticles
1a) Soaking spherical titanium dioxide nano particles in 15 wt% hydrofluoric acid for 24h, washing with water for three times, and drying to obtain acid-treated silicon dioxide nano particles;
1b) adding acid-treated spherical titanium dioxide nanoparticles and commercially available terminal aminosilane (n is 4) into toluene in a mass ratio of 1:100, uniformly stirring, reacting for 4 hours, distilling under reduced pressure to remove toluene, and drying to obtain titanium dioxide nanoparticles treated by the terminal aminosilane;
1c) uniformly mixing titanium dioxide nano particles treated by terminal amino silane, methyl dichloro (bromo) silane and acetone according to the mass ratio of 1:1, heating to 50 ℃, reacting for 6 hours, and removing the acetone through reduced pressure distillation to obtain liquid polysilazane modified spherical titanium dioxide nano particles.
2) Preparation of Silicone rubber
Taking the component A and the component B according to the mass ratio of 50:50, putting the component A and the component B into a three-roll grinder, uniformly mixing, putting the mixture into a mould, pressurizing at 160 +/-10 ℃ for 5-10 MPa, and vulcanizing for 20-30 min to obtain ultraviolet aging resistant silicon rubber (rubber sheet);
by weight: the component A is formed by uniformly mixing 80 parts of spherical nano particles modified by end polysiloxane (phenyl substitution), 50 parts of end ethoxy high phenyl vinyl organosilicon polymer and 20 parts of methyl vinyl silicone oil; the component B is formed by uniformly mixing 50 parts of Pt (main catalyst) and 20 parts of hydrogen-containing organic silicone oil (202 organic silicone oil).
The properties of the ultraviolet aging resistant silicone rubbers (films) of examples 1 to 5 were examined. Tensile strength at room temperature was measured using GB/T528. The Shore A hardness after 14 days was measured by GB/T531. The elongation at break adopts GB/T528, the detection is carried out. Test conditions of ultraviolet aging: the light source is a 20W ultraviolet lamp, and emits short-wave ultraviolet light with the characteristic wavelength of 253.7nm, and the ultraviolet irradiation intensity at the position 20cm from the vertical center of the lamp tube is 140 (VM/cm) 2 ). And putting the sample to be aged parallel to the light source into a fixed position, and carrying out an ultraviolet aging test. Ultraviolet irradiation intensity at different spatial positions in the box body is measured by using an ultraviolet irradiation meter, and sample positions (5 samples are changed in sequence after being transversely arranged) are changed at intervals of 20h, so that the ultraviolet irradiation quantity of each sample in the test time is ensured to be the same. The ultraviolet aging time is 1000h, and samples are taken out every 200h for relevant tests. The test results after 1000h are shown in table 1.
TABLE 1 Properties of UV aging resistant Silicone rubbers (films) of examples 1 to 5
Therefore, the tensile strength at room temperature of the ultraviolet aging resistant silicone rubber before ultraviolet aging is as follows: 6.2-7.0 Mpa; shore a hardness after 14 days: 50-65 parts; elongation at break: 370-400%; room temperature tensile strength after uv aging: 4.9-6.3 Mpa; shore a hardness after 14 days: 38-52; elongation at break: 550-610%, namely when the liquid polysilazane-modified spherical titanium dioxide nanoparticles are mixed with the raw silicone rubber, the nanoparticles are uniformly dispersed singly, so that the damage of ultraviolet rays to the performance of the silicone rubber can be effectively reduced, the ultraviolet aging resistance of the silicone rubber can be effectively improved, and after an ultraviolet aging test, the mechanical property retention rate of the silicone rubber is still high.
It should be understood that the above-described embodiments are merely examples for clarity of description and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither necessary nor exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the spirit or scope of the invention.
Claims (9)
1. The spherical titanium dioxide nano particle modified by polysilazane is characterized by consisting of a spherical titanium dioxide nano particle and a polysilazane grafted chain grafted on the surface of the spherical titanium dioxide nano particle;
the structural formula of the polysilazane grafted chain is as follows:
in the formula, n is an integer of 2-10;
the amino surface density of the polysilazane-modified spherical titanium dioxide nanoparticles is 7.3-30 nmol/cm 2 。
2. The method of preparing polysilazane-modified spherical titanium dioxide nanoparticles according to claim 1, comprising the steps of:
1) corroding the spherical titanium dioxide nano particles with weak acid, washing with water, and drying to obtain acid-treated spherical titanium dioxide nano particles;
2) reacting the spherical titanium dioxide nano particles subjected to acid treatment with terminal aminosilane in an organic solvent, carrying out reduced pressure distillation to remove the organic solvent, and drying to obtain spherical titanium dioxide nano particles subjected to terminal aminosilane treatment;
the structural formula of the terminal aminosilane is as follows:
in the formula, n is an integer of 2-10;
3) the terminal amino obtained in the step 2)Spherical titanium dioxide nanoparticles treated with silane and R 2 SiX 2 Reacting in an organic solvent, removing the organic solvent, and drying to obtain polysilazane-modified spherical titanium dioxide nanoparticles;
the R is 2 SiX 2 In, R 2 Is CH 3 Or Ph and X are chlorine or bromine.
3. The method for preparing polysilazane-modified spherical titanium dioxide nanoparticles according to claim 2, wherein in step 1),
the weak acid is selected from one or more of hydrofluoric acid, oxalic acid and maleic acid;
the concentration of the weak acid is 10-35 wt%;
the ratio of the spherical titanium dioxide nano particles to the weak acid is 1 g: (10-100) ml.
4. The method for producing polysilazane-modified spherical titanium dioxide nanoparticles according to claim 2, wherein in step 2),
the mass ratio of the spherical titanium dioxide nano particles after acid treatment to the terminal aminosilane is 1: 100;
the organic solvent is toluene;
the reaction time is 4 h.
5. The method for preparing polysilazane-modified spherical titanium dioxide nanoparticles according to claim 2, wherein in step 3),
the organic solvent is acetone;
the reaction temperature is 50 ℃;
the reaction time was 6 h.
6. The ultraviolet aging resistant silicone rubber is characterized in that the raw materials comprise a component A and a component B in a mass ratio of 50: 50;
the component A is formed by uniformly mixing 20-80 parts by weight of the polysilazane-modified spherical titanium dioxide nanoparticles as defined in claim 1, 30-80 parts by weight of an ethoxy-terminated high phenyl vinyl silicone polymer and 20-30 parts by weight of methyl vinyl silicone oil, and the component B is formed by uniformly mixing 20-80 parts by weight of a palladium catalyst and 10-20 parts by weight of hydrogen-containing silicone oil;
the structural formula of the end ethoxy high phenyl vinyl organosilicon polymer is as follows:
the average molecular weight of the terminal ethoxy high phenyl vinyl organosilicon polymer is 11000-61000.
7. The UV aging resistant silicone rubber according to claim 6, wherein the component A is prepared by uniformly mixing 30-80 parts by weight of polysilazane-modified spherical titanium dioxide nanoparticles, 40-50 parts by weight of terminal ethoxy high phenyl vinyl silicone polymer and 20 parts by weight of methyl vinyl silicone oil, and the component B is prepared by uniformly mixing 20-50 parts by weight of palladium catalyst and 10-20 parts by weight of hydrogen-containing silicone oil.
8. The method for preparing the ultraviolet aging resistant silicone rubber of claim 6 or 7, characterized by comprising the steps of:
weighing the component A and the component B according to the proportion, uniformly mixing, placing in a mold, pressurizing, heating and vulcanizing to obtain the ultraviolet aging resistant silicone rubber.
9. The method for preparing the ultraviolet aging resistant silicone rubber according to claim 6 or 7, characterized in that a three-roll grinder is used to mix the component A and the component B uniformly; the vulcanization temperature is 160 +/-10 ℃, the vulcanization pressure is 5-10 MPa, and the vulcanization time is 20-30 min.
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| JP2009040967A (en) * | 2007-08-10 | 2009-02-26 | Panasonic Electric Works Co Ltd | Resin composition for forming low refractive index film, low refractive index film, and reflection-preventing substrate |
| CN109943207A (en) * | 2019-03-27 | 2019-06-28 | 浙江中科应化科技有限公司 | A kind of modified polyurea coating |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009040967A (en) * | 2007-08-10 | 2009-02-26 | Panasonic Electric Works Co Ltd | Resin composition for forming low refractive index film, low refractive index film, and reflection-preventing substrate |
| CN109943207A (en) * | 2019-03-27 | 2019-06-28 | 浙江中科应化科技有限公司 | A kind of modified polyurea coating |
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| JULIA EHBETS，ETAL.: "Synthesis and Hydrolysis of Alkoxy(aminoalkyl)diorganylsilanes of the Formula Type R2(RO)Si(CH2)nNH2 (R = Alkyl, n = 1–3): A Systematic Experimental and Computational Study" * |
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