阅读说明：本技术 高强度共聚氟硅橡胶组合物、制备方法 (High-strength copolymerized fluorosilicone rubber composition and preparation method thereof ) 是由 陈志强 于 2020-04-10 设计创作，主要内容包括：本发明涉及橡胶技术领域,具体涉及高强度共聚氟硅橡胶组合物、制备方法,按重量份数计,包括100份共聚氟硅生胶、30～70份气相法白炭黑、4～12份粘度(25℃)90～120mPa·s羟基氟硅油、0～10份高乙烯基氟硅油、1-2份双二五硫化剂和0-2份颜料,其中共聚氟硅生胶的高分子链的侧链上含有三氟丙基笼型聚倍半硅氧烷。本发明的高强度共聚氟硅橡胶组合物硫化后具有较好的力学强度,耐高温性能也有提升,引入少量的三氟丙基笼型聚倍半硅氧烷就可以明显提升耐燃油性,综合性能较好。(The invention relates to the technical field of rubber, in particular to a high-strength copolymerized fluorosilicone rubber composition and a preparation method thereof, wherein the high-strength copolymerized fluorosilicone rubber composition comprises, by weight, 100 parts of copolymerized fluorosilicone raw rubber, 30-70 parts of fumed silica, 4-12 parts of hydroxyl fluorosilicone oil with the viscosity (25 ℃) of 90-120 mPa & s, 0-10 parts of high vinyl fluorosilicone oil, 1-2 parts of bis-penta vulcanizing agent and 0-2 parts of pigment, wherein the side chain of the high molecular chain of the copolymerized fluorosilicone raw rubber contains trifluoropropyl polyhedral oligomeric silsesquioxane. The high-strength copolymerized fluorosilicone rubber composition has better mechanical strength and improved high-temperature resistance after being vulcanized, can obviously improve fuel resistance by introducing a small amount of trifluoropropyl cage polysilsesquioxane, and has better comprehensive performance.)

1. The high-strength copolymerized fluorosilicone rubber composition is characterized in that: the coating comprises, by weight, 100 parts of a copolymerized fluorosilicone crude rubber, 30-70 parts of fumed silica, 4-12 parts of 90-120 mPa.s hydroxyl fluorosilicone oil with viscosity (25 ℃), 0-10 parts of high vinyl fluorosilicone oil, 1-2 parts of a bis-penta vulcanizing agent and 0-2 parts of a pigment; the chemical structure of the copolymerization fluorine-silicon crude rubber is shown as a formula (I),

wherein R is_fis-CH₂CH₂CF₃，R¹And R²Each independently selected from methyl, vinyl or hydroxyl, 0.005-a/(b + c) -00.1，b≥700，300≤c≤b，0＜d≤10。

2. The high-strength copolymerized fluorosilicone rubber composition according to claim 1, wherein: the copolymerized fluorosilicone crude rubber is obtained by heating, ring-opening and polymerizing siloxane ring bodies, trimethyl tri (trifluoropropyl) cyclotrisiloxane, octamethylcyclotetrasiloxane and tetramethyl tetravinylcyclotetrasiloxane with the chemical structure shown in the formula (II) under the condition of a silicon alkoxide catalyst;

wherein R is_f1The chemical structure of the compound is shown as a formula (III),

wherein R is_fis-CH₂CH₂CF₃。

3. The high-strength copolymerized fluorosilicone rubber composition according to claim 2, wherein: the siloxane ring body is obtained by carrying out hydrosilylation reaction on cage type polysilsesquioxane I and tetramethyl tetravinylcyclotetrasiloxane with the chemical structure shown in the formula (IV).

Wherein R is_fis-CH₂CH₂CF₃。

4. The high-strength copolymerized fluorosilicone rubber composition according to claim 3, wherein: the cage-type polysilsesquioxane is prepared by reacting trifluoropropyl silsesquioxane trisilicol or trifluoropropyl silsesquioxane trisilicol salt obtained by hydrolytic condensation of (trifluoropropyl) trimethoxysilane, (trifluoropropyl) triethoxysilane or (trifluoropropyl) trichlorosilane with trichlorosilane, trimethoxysilane or triethoxysilane.

5. The high-strength copolymerized fluorosilicone rubber composition according to claim 2, wherein: the siloxane ring body is obtained by carrying out hydrosilylation reaction on cage type polysilsesquioxane di-and tetramethylcyclotetrasiloxane with the chemical structure shown in the formula (V).

Wherein R is_fis-CH₂CH₂CF₃。

6. The high-strength copolymerized fluorosilicone rubber composition according to claim 5, wherein: the cage-type polysilsesquioxane II is prepared by reacting trifluoropropyl silsesquioxane trisilicol or trifluoropropyl silsesquioxane trisilicol salt obtained by hydrolytic condensation of (trifluoropropyl) trimethoxysilane, (trifluoropropyl) triethoxysilane or (trifluoropropyl) trichlorosilane with vinyl trichlorosilane, vinyl trimethoxysilane or vinyl triethoxysilane.

7. The high-strength copolymerized fluorosilicone rubber composition according to claim 1, wherein: the BET method specific surface area of the fumed silica is 50-300 m²/g。

8. The high-strength copolymerized fluorosilicone rubber composition according to claim 1, wherein: the viscosity (25 ℃) of the high-vinyl fluorosilicone oil is 100-1000 mPa & s, and the mass percentage content of vinyl is 3-10%.

9. The method for preparing a high-strength copolymerized fluorosilicone rubber composition according to any one of claims 1 to 8, wherein: accurately weighing each raw material component according to a formula, adding the copolymerized fluorosilicone crude rubber into an internal mixer, adding the fumed silica and the hydroxy fluorosilicone oil in batches, uniformly stirring, reducing the pressure to below-0.07 MPa, heating to 150-180 ℃, continuously stirring for 30-60 minutes, and cooling to obtain the copolymerized fluorosilicone rubber base; and placing the obtained copolymer fluorosilicone rubber base rubber in a three-roll machine, performing thin passing three times at the roll distance of 3-5 mm, adding high vinyl fluorosilicone oil, adjusting the roll distance to 1-2 mm, performing thin passing three times, adding pigment, adjusting the roll distance to 1-2 mm, performing thin passing three times, adding a Bitwenty-five vulcanizing agent, and performing thin passing 3-5 times to obtain the high-strength copolymer fluorosilicone rubber composition.

Technical Field

The invention relates to the technical field of rubber, in particular to a high-strength copolymerized fluorosilicone rubber composition and a preparation method thereof.

Background

The fluorine-containing group is introduced to the side chain of the Si-O main chain, so that the fluorine-containing silicone rubber integrates the heat resistance, the cold resistance, the weather aging resistance and the like of an organic silicon material and the hydrocarbon solvent resistance, the oil resistance and the like of an organic fluorine material, is a unique elastomer which can resist a nonpolar medium at the temperature of-68-232 ℃, is particularly suitable for applications needing high temperature resistance and fuel oil resistance, such as sealing elements, rubber tubes, rubber mats, dipped products and the like, and has wide application in the fields of the automobile industry, the aerospace industry, the petrochemical industry and the like.

But instead of the other end of the tubePure fluorosilicone rubber has high cost, and may be used in some places with less fuel oil resistance requirement. There are two types of blended fluorosilicone rubbers: one is the physical blending of silicone rubber and fluorine silicone rubber, but because the polarity difference of the silicone rubber and the fluorine silicone rubber is too large, the silicone rubber and the fluorine silicone rubber cannot be blended microscopically, so that the silicone rubber and the fluorine silicone rubber are separated after vulcanization and cannot be used practically; the other is chemical blending, namely the crude rubber polymer chain of the fluorosilicone rubber consists of trifluoropropyl methyl siloxane chain links and dimethyl siloxane chain links, and is composed of tri (trifluoropropyl) trimethyl cyclotrisiloxane (D)₃ ^F) Octamethylcyclotetrasiloxane (D)₄) And a small amount of tetramethyltetravinylcyclotetrasiloxane (D)₄ ^vi) Ring-opening polymerization is carried out.

The preparation, physical property research and application of the copolymerized fluorosilicone rubber are reviewed in the research progress of the copolymerized fluorosilicone rubber (the seventeenth proceedings of the society of organic silicon science in 2014).

Preparation and performance of copolymerized fluorosilicone rubber from Master thesis of Zhejiang university 2014D through initiator and accelerator₃ ^FAnd hexamethylcyclotrisiloxane (D)₃) The ring-opening polymerization is carried out to prepare the copolymer fluorosilicone raw rubber, nano silicon oxide is adopted for reinforcement, a structure control agent is matched, and a vulcanizing agent is added for vulcanization to obtain the copolymer fluorosilicone rubber.

However, the problems of low mechanical strength and insufficient heat resistance of the copolymerized fluorosilicone rubber exist at present.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide the high-strength copolymerized fluorosilicone rubber composition, and the vulcanized copolymerized fluorosilicone rubber has better mechanical property, oil resistance and high temperature resistance.

It is another object of the present invention to provide a method for preparing the high-strength copolymerized fluorosilicone rubber composition.

The invention adopts the following technical scheme:

the high-strength copolymer fluorosilicone rubber composition comprises, by weight, 100 parts of copolymer fluorosilicone raw rubber, 30-70 parts of fumed silica, 4-12 parts of 90-120 mPa.s hydroxyl fluorosilicone oil with viscosity (25 ℃), 0-10 parts of high vinyl fluorosilicone oil, 1-2 parts of a bis-penta vulcanizing agent and 0-2 parts of a pigment; the chemical structure of the copolymerization fluorine-silicon crude rubber is shown as a formula (I),

wherein R is_fis-CH₂CH₂CF₃，R¹And R²Each independently selected from methyl, vinyl or hydroxyl, a/(b + c) is more than or equal to 0.005 and less than or equal to 0.1, b is more than or equal to 700, c is more than or equal to 300 and less than or equal to b, and d is more than 0 and less than or equal to 10.

Preferably, the copolymerization fluorosilicone raw rubber is prepared from siloxane ring bodies with a chemical structure shown in formula (II) and D₃ ^F、D₄、D₄ ^viHeating to open ring and polymerize under the presence of a silicon alkoxide catalyst to obtain the product;

wherein R is_f1The chemical structure of the compound is shown as a formula (III),

wherein R is_fis-CH₂CH₂CF₃。

The silicon alkoxide catalyst can be selected from a silicon alkoxide potassium catalyst (potassium gel for short) or a tetramethyl ammonium hydroxide silicon alkoxide catalyst (ammonium gel for short). The specific procedure of the ring-opening polymerization by heating may be as follows: the siloxane ring body, D₃ ^F、D₄And D₄ ^viAdding the mixture into a container after dewatering, heating to 70 ℃, introducing nitrogen for protection, adding ammonium glue, heating to 110-120 ℃, reacting at constant temperature until a stirring rod can not rotate, stopping stirring, reacting at the constant temperature for 1 hour, adjusting the pressure of a reaction system to-0.08 to-0.05 MPa, heating to 140 ℃ to destroy a catalyst for 0.5 hour, adjusting the pressure to below-0.098 MPa, heating to 160-170 ℃ to remove low-boiling-point substances until no low-boiling-point substances are removed, and obtaining the productRaw polyfluorosilicate rubber.

The specific steps of the ring-opening polymerization by heating may also be as follows: the siloxane ring body, D₃ ^F、D₄And D₄ ^viWater removal treatment of the siloxane Ring bodies, D₄And D₄ ^viAdding into a container, heating to 110-120 ℃, introducing nitrogen for protection, adding potassium gel, heating to 140-150 ℃, reacting for 0.5 h, adding D₃ ^FControlling the temperature at 110-120 ℃ for reaction until the stirring rod can not stir, stopping stirring, carrying out heat preservation reaction for 1 hour, and cooling to obtain the unneutralized copolymerized fluorosilicone crude rubber. Transferring the non-neutralized fluorosilicone crude rubber into a kneader, adding a proper amount of a neutralizing agent such as silicon-based phosphate for stirring and neutralizing, reducing the pressure to be below-0.098 MPa, and heating to 160-170 ℃ to remove low-boiling-point substances to obtain the copolymerized fluorosilicone crude rubber.

More preferably, the siloxane ring body is obtained by hydrosilylation reaction of cage polysilsesquioxane-POSS (polyhedral oligomeric silsesquioxane for short) and tetramethyl tetravinylcyclotetrasiloxane, the chemical structure of which is shown in formula (IV).

Wherein R is_fis-CH₂CH₂CF₃。

The hydrosilylation reaction is an important means for preparing modified organosilicon compounds, and organic compounds containing carbon-carbon unsaturated double bonds or organosilicon compounds and organosilicon compounds containing silicon hydrogen bonds are subjected to addition reaction in a hydrosilylation catalyst, mainly a plurality of noble metal catalysts.

Further preferably, the POSS is prepared by reacting trifluoropropyl silsesquioxane trisilicol obtained by hydrolytic condensation of (trifluoropropyl) trimethoxysilane, (trifluoropropyl) triethoxysilane or (trifluoropropyl) trichlorosilane with trichlorosilane, trimethoxysilane or triethoxysilane.

Journal article Precision Synthesis of Fluorinated polymeric oligomer catalysts-Terminated Polymer and Surface Characterization of Its Mass end Polymer with Poly (methyl methacrylate), discloses that trifluoropropyltrimethoxysilane is used as raw material, sodium hydroxide and water are controlled to obtain sodium trisilicate of fluoropropylS successfully, and POST is further functionalized by a vertex-capping reaction.

A research on synthesis, characterization and self-assembly behavior of an amphiphilic block copolymer containing fluoropropyl caged silsesquioxane (POSS) reported by doctor of Shanghai university of transportation in 2008 reports a preparation method of trifluoropropyl POSS trisilanol sodium salt, wherein trifluoropropyl trimethoxy silane is prepared by continuously reacting at room temperature after reflux reaction in the presence of tetrahydrofuran, deionized water and sodium hydroxide, and drying after removing a solvent. And reacting trifluoropropyl POSS trisilanol sodium salt with 3-cyanopropyl trichlorosilane in the presence of triethylamine in an ice water bath, continuously reacting at room temperature, purifying and drying to obtain the 3-cyanopropyl hepta (trifluoropropyl) POSS.

Therefore, the sodium salt of hepta (trifluoropropyl) silsesquioxane trisilanol is further combined with the general structural formula of RSiX₃The silane coupling agent can be used for preparing monofunctional group hepta (trifluoropropyl) POSS by reaction, wherein R is an organic group, specifically hydrogen group, vinyl, methyl and the like, and X is-Cl-OCH₃Or OCH₂CH₃。

Journal literature, Nanostructures and Surface Dewettabilities of Epoxy thermosets containing Hepta (3,3,3-trifluoropropyl), discloses a method for preparing Hepta (trifluoropropyl) hydrosilyl trisilicon sodium salt by reacting Hepta (trifluoropropyl) Silsesquioxane sodium salt with trichlorosilane, and then performing a hydrosilylation reaction with allyl polyethylene glycol to obtain Hepta (trifluoropropyl) POSS-terminated polyethylene glycol.

More preferably, the siloxane ring body is obtained by hydrosilylation reaction of POSS di-and tetramethylcyclotetrasiloxane with the chemical structure as shown in formula (V).

Wherein R is_fis-CH₂CH₂CF₃。

Further preferably, the POSS is prepared by reacting trifluoropropyl silsesquioxane trisilicol obtained by hydrolytic condensation of (trifluoropropyl) trimethoxysilane, (trifluoropropyl) triethoxysilane or (trifluoropropyl) trichlorosilane with vinyltrichlorosilane, vinyltrimethoxysilane or vinyltriethoxysilane.

Preferably, the BET specific surface area of the fumed silica is 50-300 m²/g。

Preferably, the viscosity (25 ℃) of the high-vinyl fluorosilicone oil is 100-1000 mPa · s, and the mass percentage content of vinyl is 3-10%.

According to the preparation method of the high-strength copolymerized fluorosilicone rubber composition, the raw materials are accurately weighed according to the formula, the copolymerized fluorosilicone rubber is added into an internal mixer, the fumed silica and the hydroxy fluorosilicone oil are added in batches, after being uniformly stirred, the pressure is reduced to be below-0.07 MPa, the temperature is raised to 150-180 ℃, the stirring is continued for 30-60 minutes, and the temperature is reduced to obtain the copolymerized fluorosilicone rubber base rubber; and placing the obtained copolymer fluorosilicone rubber base rubber in a three-roll machine, performing thin passing three times at the roll distance of 3-5 mm, adding high vinyl fluorosilicone oil, adjusting the roll distance to 1-2 mm, performing thin passing three times, adding pigment, adjusting the roll distance to 1-2 mm, performing thin passing three times, adding a Bitwenty-five vulcanizing agent, and performing thin passing 3-5 times to obtain the high-strength copolymer fluorosilicone rubber composition.

The invention has the beneficial effects that:

(1) according to the invention, POSS molecules are introduced on the side chain of the copolymer fluorosilicone crude rubber macromolecular chain, and compared with trifluoropropyl, methyl and vinyl, the POSS molecules have larger molecular size, so that when the copolymer fluorosilicone rubber is acted by external force, the larger POSS molecules enable the fluorosilicone crude rubber macromolecular chain to be wound more tightly and can resist the destructive action of the external force, thus the mechanical strength of the copolymer fluorosilicone rubber is improved, the tensile strength reaches more than 9MPa, the tearing strength reaches more than 37KN/m, and the compression permanent deformation can be reduced to below 13%.

(2) According to the invention, POSS is introduced into the side chain of the copolymer fluorosilicone crude rubber polymer chain, each POSS molecule has seven trifluoropropyl groups, and the number of trifluoropropyl groups of the copolymer fluorosilicone crude rubber is increased, so that the copolymer fluorosilicone rubber has better fuel resistance by introducing a small amount of POSS.

Detailed Description

The technical solution of the present invention is further illustrated and described by the following detailed description.

Unless otherwise specified, the parts in the following embodiments are parts by weight.