Patent Description:
At present, the primary problem faced by the improvement of safety and comprehensive benefits of the oil and gas well drilling is the failure accident of the down-hole drilling tool, and the economical loss caused by the failure of the drilling tool cannot be underestimated. According to the statistics, about <NUM>% of drilling tool failure accidents are caused by the failure of joints and threads of the drilling tool. Through a large number of failure analysis and research, it is found that most of the failures of drilling tools are due to the wear of joints and threads of the drilling tools, which reduces the torsional strength of the connections and fails under the action of alternating bending stress. Due to the limited length of the joint of the drill pipe, the main tongs clamp the pipe body to buckle and unbuckle, the buckle torque is large, and the tooth scars of the main tongs will become larger. Among the various surface scars on the drill pipe, the tooth scars of the main tongs are the most common and serious, which can easily form stress concentration points and induce the failure of joints and threads of the drilling tools. Therefore, it is a problem that cannot be ignored to reduce the tooth scars damage on the drill pipe body caused by the tongs.

Nitrile rubber is widely used in the manufacture of oil-resistant products such as sealing articles, gaskets and the like due to the excellent oil resistance. However, the using temperature range of nitrile rubber is limited, which cannot meet the on-site working conditions of the protective tooth blocks in drilling tongs. The high temperature environment will reduce the aging resistance of nitrile rubber, thus declining its mechanical properties rapidly. Therefore, the preparation of a nitrile rubber with better mechanical properties is of great significance in practical applications.

Chinese Patent <CIT> discloses a graphene-modified nitrile rubber and a preparation method thereof. The method utilizes the product obtained by the dehydration condensation reaction of hydrolyzed mercaptosiloxane and graphene oxide to modify the nitrile rubber, which has more improved mechanical properties than the unmodified nitrile rubber. However, this method does not consider the interfacial compatibility between the filler and the rubber, and the dispersion of the filler in the rubber, so does not have applicability and versatility. And the filler can only be carbon black, that will increase the using amount of the modified graphene oxide and is not economical.

Chinese Patent <CIT> discloses a preparation method of silica-grafted graphene oxide/rubber composite material. The method utilizes silica-grafted graphene oxide to modify rubber, which has improved heat resistance and wear resistance than unmodified rubber. However, this method does not take into account that the silica has acid radical residues, and after being used for modification, the material is prone to yellowing and poor weather resistance.

Besides, <CIT> refers to elastomeric compositions comprising graphite nanoparticles.

Therefore, the nitrile rubber in the related art may suffer from reduced mechanical properties and compatibility problems at the interface between filler and rubber due to the limited temperature range.

The purpose of the present invention relates to a functionalized graphene oxide nitrile rubber and a preparation method of a tooth-scar-free tooth block, wherein the functionalized graphene oxide nitrile rubber has excellent mechanical properties, a wide range of applicable temperatures and strong stability. The problems of poor mechanical properties and interfacial compatibility between the fillers and the rubber caused by the limited using temperature range of nitrile rubber in the related art are well solved. The method for preparing a tooth-scar-free tooth block by using the functionalized graphene oxide nitrile rubber of the present invention has the advantages of simple process, low cost, and the manufactured tooth-scar-free tooth block has excellent mechanical properties and strong stability.

The present invention relates to a functionalized graphene oxide nitrile rubber mixture, comprising the following components in parts by weight: <NUM>-<NUM> parts of nitrile rubber, <NUM>-<NUM> parts of functionalized graphene oxide nitrile rubber masterbatch, <NUM>-<NUM> parts of vulcanizing agent, <NUM>-<NUM> parts of vulcanization accelerator, <NUM>-<NUM> parts of vulcanization activator, <NUM>-<NUM> parts of plasticizer, <NUM>-<NUM> parts of antioxidant, <NUM>-<NUM> parts of filler, <NUM>-<NUM> part of curing agent and <NUM>-<NUM> parts of dichlorophenol (DCP).

Wherein, the plasticizer may be a mixture of stearic acid, dibutyl phthalate and tricresyl phosphate with a mass ratio of <NUM>-<NUM>:<NUM>-<NUM>:<NUM>-<NUM>; the antioxidant may be a mixture of antioxidant D and antioxidant <NUM> with a mass ratio of <NUM>:<NUM>; the mass fraction of the functionalized graphene oxide in the functionalized graphene oxide nitrile rubber masterbatch is <NUM>-<NUM>%.

The present invention further relates to a functionalized graphene oxide modified tooth-scar-free tooth block, which is made of the functionalized graphene oxide nitrile rubber as described above, and the preparation process comprises the following steps:.

The method for preparing the tooth-scar-free tooth block provided by the present invention is simple in process and low in cost. By adding the functionalized graphene oxide and the epoxy resin in the formula, the prepared functionalized graphene oxide modified nitrile rubber tooth block has excellent mechanical properties, a wide range of applicable temperatures and strong stability, and solves the problem of poor mechanical properties due to the limited using temperature range and interface compatibility between the filler and the rubber of the nitrile rubber in the related art.

A first aspect of the present invention provides a functionalized graphene oxide nitrile rubber mixture, comprising the following components in parts by weight: <NUM>-<NUM> parts of nitrile rubber, <NUM>-<NUM> parts of functionalized graphene oxide nitrile rubber masterbatch, <NUM>-<NUM> parts of vulcanizing agent, <NUM>-<NUM> parts of vulcanization accelerator, <NUM>-<NUM> parts of vulcanization activator, <NUM>-<NUM> parts of plasticizer, <NUM>-<NUM> parts of antioxidant, <NUM>-<NUM> parts of filler, <NUM>-<NUM> part of curing agent and <NUM>-<NUM> parts of dichlorophenol (DCP).

Wherein, the mass fraction of functionalized graphene oxide in the functionalized graphene oxide nitrile rubber masterbatch is <NUM>-<NUM>%; the vulcanizing agent may be sulfur; the vulcanization accelerator may be accelerator DM (<NUM>,<NUM>'-dibenzothiazoledisulfde); the vulcanization activator may be zinc oxide; the plasticizer may be a mixture of stearic acid, dibutyl phthalate and tricresyl phosphate with a mass ratio of <NUM>-<NUM>:<NUM>-<NUM>:<NUM>-<NUM>, preferably <NUM>:<NUM>:<NUM>; the antioxidant may be a mixture of antioxidant D (N-Phenyl-<NUM>-naphthylamine) and antioxidant <NUM> (N-cyclohexyl-N'-phenyl-p-phenylenediamine) with a mass ratio of <NUM>:<NUM>; the filler is a mixture of gas-mixture carbon black, semi-reinforcing furnace black and epoxy resin E44 (E44 represents that the epoxy resin has an average epoxy value of <NUM>/<NUM>), the preferred mass ratio is <NUM>:<NUM>:<NUM>; and the curing agent may be maleic anhydride.

When the functionalized graphene oxide is uniformly dispersed in the nitrile rubber system, the motion capability of the molecular chain in the nitrile rubber is largely limited by the sheet-like functionalized graphene oxide having a large specific surface area, so that the nitrile rubber exhibits a higher using temperature range. Moreover, the intrinsic strength of the graphene reaches 130GPa, the fracture strain is about <NUM>%, and the elastic modulus can reach <NUM> TPa. The tensile strength of the graphene can be up to <NUM> N/m2, which is about <NUM> times that of the ordinary steel calculated by the two-dimensional strength limit theory. The experimental results show that the mechanical properties of the tooth blocks made of functionalized graphene oxide modified nitrile rubber have been significantly improved. During high temperature vulcanization, the epoxy resin and the curing agent undergo in-situ polymerization in the rubber compound to form nanoscale particles or fibers, or to form a local interpenetrating network structure with the rubber molecules, and the comprehensive performance of the rubber compound is improved. The epoxy resin as an interface additive between the non-polar unsaturated rubber, the filler and the graphene oxide, forms a bridge function at the interface between the filler and the rubber, and the dispersion degree and the reinforcing effect of the filler are improved.

The preparation method of the functionalized graphene oxide nitrile rubber masterbatch comprises the following steps: dispersing the functionalized graphene oxide in a dispersant, ultrasonically dispersing for <NUM>-<NUM> minutes to obtain a functionalized graphene oxide dispersion, adding nitrile rubber latex and stirring for <NUM>-<NUM> to obtain a mixed solution, wherein the mass of the functionalized graphene oxide accounts for <NUM>-<NUM>% of the mass of the mixed solution. The mixed solution above is added to a mixed liquid of a calcium chloride aqueous solution and ethanol with a volume ratio of <NUM>:<NUM>-<NUM> used as a coagulation solution for demulsification, wherein the volume ratio of the mixed solution to the coagulation solution is <NUM>-<NUM>:<NUM>-<NUM>, after suction filtration, washing and drying, a functionalized graphene oxide nitrile rubber masterbatch is obtained.

The dispersant can be a mixture of xylene, n-butanol, cyclohexanone, <NUM>,<NUM> butanediol diglycidyl ether, and the mass ratio thereof may be <NUM>-<NUM>:<NUM>-<NUM>:<NUM>-<NUM>:<NUM>-<NUM>, the preferred mass ratio is <NUM>:<NUM>:<NUM>:<NUM>. The solid content of the nitrile rubber latex may be <NUM>-<NUM>%.

The preparation method of the above-described functionalized graphene oxide is preparing graphene oxide (GO) by a modified Hummers method; adding the GO and <NUM>-Aminopropyltrimethoxysilane (APTMS) as a modifier with a mass ratio of <NUM>:<NUM> into an anhydrous ethanol and ultrasonic stirring uniformly; heating to <NUM>-<NUM> in a water bath and refluxing for <NUM>-<NUM> hours; then adding distilled water to the mixture, centrifuging, washing and drying to obtain Aminated Graphene (APTMS-GO), the lamellar spacing of which may be <NUM>. In the above-described preparation method of functionalized graphene oxide, in the mixture of GO, APTMS and anhydrous ethanol, the mass content of anhydrous ethanol can be <NUM>%. Wherein, the drying temperature is <NUM>-<NUM>, and the drying time is <NUM>-<NUM>.

After graphene oxide is functionalized, the lamellar spacing of the graphene becomes larger, which can better bound the movement of rubber molecular chains and epoxy resin molecular chains, so that the tooth block made of rubber modified by functionalized graphene oxide can have a wider using temperature range; and the functionalized graphene oxide is easier to uniformly disperse in the rubber matrix due to the presence of more active functional groups on the surface of the functionalized graphene oxide. Due to the good dispersion performance, the defects in the rubber are reduced, so that the modified rubber has better mechanical properties.

A second aspect of the present invention relates to a tooth-scar-free tooth block made of functionalized graphene oxide nitrile rubber, which is made of the functionalized graphene oxide nitrile rubber as described above, and the preparation process comprises the following steps:.

The present invention will be further described in detail below with reference to specific examples.

A functionalized graphene oxide modified tooth-scar-free tooth block, using functionalized graphene oxide nitrile rubber as the raw material, comprising the following components in parts by weight:.

<NUM> parts of nitrile rubber, <NUM> parts of functionalized graphene oxide nitrile rubber masterbatch, <NUM> parts of vulcanizing agent, <NUM> parts of vulcanization accelerator, <NUM> parts of vulcanization activator, <NUM> parts of plasticizer, <NUM> parts of antioxidant, <NUM> parts of filler, <NUM> part of curing agent and <NUM> parts of dichlorophenol (DCP).

Wherein, the vulcanizing agent is sulfur; the vulcanization accelerator is accelerator DM; the vulcanization activator is zinc oxide; the plasticizer is stearic acid, dibutyl phthalate and tricresyl phosphate with a mass ratio of <NUM>:<NUM>:<NUM>; the antioxidant is a mixture of antioxidant D and antioxidant <NUM> with a mass ratio of <NUM>:<NUM>; the filler is gas-mixture carbon black, semi-reinforcing furnace black and epoxy resin E44 with a mass ratio of <NUM>:<NUM>:<NUM>; and the curing agent can be maleic anhydride.

The preparation method of the functionalized graphene oxide nitrile rubber masterbatch comprises the following steps: dispersing the functionalized graphene oxide in a dispersant, ultrasonically dispersing for <NUM>-<NUM> minutes to obtain a functionalized graphene oxide dispersion, adding nitrile rubber latex and stirring for <NUM>-<NUM> to obtain a mixed solution, wherein the mass of the functionalized graphene oxide accounts for <NUM>-<NUM>% of the mass of themixed solution. The mixed solution above is added to a mixed liquid of a calcium chloride aqueous solution and ethanol with a volume ratio of <NUM>:<NUM>-<NUM> used as a coagulation solution for demulsification, wherein the volume ratio of the mixed solution to the coagulation solution is <NUM>-<NUM>:<NUM>-<NUM>, after suction filtration, washing and drying, a functionalized graphene oxide nitrile rubber masterbatch is obtained.

A method for preparing the functionalized graphene oxide modified tooth-scar-free tooth block as described above, comprising the following steps:.

A functionalized graphene oxide modified tooth-scar-free tooth block, using a functionalized graphene oxide nitrile rubber as the raw material, the functionalized graphene oxide nitrile rubber comprising the following components in parts by weight:
<NUM> parts of nitrile rubber, <NUM> parts of functionalized graphene oxide nitrile rubber masterbatch, <NUM> parts of vulcanizing agent, <NUM> parts of vulcanization accelerator, <NUM> parts of vulcanization activator, <NUM> parts of plasticizer, <NUM> parts of antioxidant, <NUM> parts of filler, <NUM> part of curing agent and <NUM> parts of dichlorophenol (DCP).

A functionalized graphene oxide modified tooth-scar-free tooth block, using functionalized graphene oxide nitrile rubber as the raw material, comprising the following components in parts by weight:
<NUM> parts of nitrile rubber, <NUM> parts of functionalized graphene oxide nitrile rubber masterbatch, <NUM> parts of vulcanizing agent, <NUM> parts of vulcanization accelerator, <NUM> parts of vulcanization activator, <NUM> parts of plasticizer, <NUM> parts of antioxidant, <NUM> parts of filler, <NUM> part of curing agent and <NUM> parts of dichlorophenol (DCP).

A graphene modified nitrile rubber, comprising the following components in parts by weight:
<NUM> parts of nitrile rubber, <NUM> parts of modified graphene oxide carboxyl nitrile rubber masterbatch, <NUM> parts of vulcanizing agent, <NUM> parts of vulcanization accelerator, <NUM> parts of vulcanization activator, <NUM> parts of plasticizer, <NUM> parts of antioxidant and <NUM> parts of filler.

Wherein, the nitrile rubber is carboxyl nitrile rubber, the content of bound acrylonitrile in the carboxyl nitrile rubber is <NUM>-<NUM>%, the content of carboxyl is <NUM>-<NUM>%; the modified graphene oxide carboxyl nitrile rubber masterbatch is modified graphene oxide carboxyl nitrile rubber masterbatch II; the vulcanizing agent is benzoyl peroxide, the vulcanization accelerator is <NUM> parts of N-oxodiethylidene-<NUM>-benzothiazole subsulfonamide and <NUM> parts of zinc diethyldithiocarbamate; the vulcanization activator is zinc oxide; the plasticizer is dioctyl azelate; the antioxidant is <NUM>,<NUM>,<NUM>-trimethyl -<NUM>-dihydroquinoline polymer; and the filler is furnace carbon black with an average particle size of <NUM>-<NUM>.

Modified graphene oxide carboxyl nitrile rubber masterbatch II can be prepared from carboxyl nitrile latex and modified graphene oxide. The preparation process is as follows:.

It should be noted that, the content of each substance in the above preparation process is only for illustrative use, and the increase or decrease of a fixed ratio on the basis of the above numerical range are all within the protection scope of the present invention.

A modified nitrile rubber, comprising the following components in parts by weight:.

Preparation of silica-grafted graphene oxide nanoparticles: using flake graphite as raw material, using Hummers oxidation method to prepare graphite oxide, and forming an uniformly dispersed graphene oxide mixed solution with a mass concentration of <NUM>/ml by 1000W ultrasonic treatment; adding <NUM> of sodium silicate, <NUM> of deionized water to a <NUM> conical flask, dripping <NUM> of concentrated hydrochloric acid, and stirring at <NUM> for <NUM>; pouring the reaction solution into a <NUM> beaker, adding <NUM> of tetrahydrofuran, and adding <NUM> of sodium chloride, stirring uniformly, using a separatory funnel for liquid separation, discarding the lower clear liquid, adding <NUM> of anhydrous magnesium sulfate to the upper organic liquid and standing overnight, filtering to obtain silica sol; adding <NUM> of the ultrasonically dispersed graphene oxide mixed solution and placing the same in a high-pressure reactor, adding <NUM> of silica sol, placing the reactor in an <NUM> oven, reacting at a constant temperature for <NUM>, filtering and washing, and drying to obtain gray-black powder, which is the silica-grafted modified graphene oxide composite material.

A silica-grafted graphene oxide/rubber composite material, the mass fraction of each component is: <NUM> parts of ribbed smoked sheet, <NUM> parts of super wear-resistant carbon black, <NUM> parts of white carbon black, and <NUM> parts of silica-grafted graphene oxide nanoparticles, <NUM> parts silane coupling agent, <NUM> parts heat stabilizer HS-<NUM>, <NUM> parts zinc oxide, <NUM> parts stearic acid, <NUM> parts antioxidant <NUM>, <NUM> part antioxidant RD, <NUM> parts protective wax, <NUM> parts of insoluble sulfur IS-<NUM>, <NUM> part of accelerator NOBS, and <NUM> part of accelerator DZ, which are uniformly mixed in an internal mixer to prepare a silica-grafted graphene oxide/rubber composite material.

<FIG> is a transmission electron microscope image of graphene oxide and functionalized graphene oxide, wherein the Image a is graphene oxide, and the Image b is functionalized graphene oxide. <FIG> is an infrared spectrogram of graphene oxide and functionalized graphene oxide, the abscissa is the wave number per centimeter, and the ordinate is the transmittance.

The modified rubber tooth block prepared in Example <NUM> and the modified nitrile rubber prepared in Comparative Examples <NUM>-<NUM> were tested as follows:.

As can be seen from the table, compared with the modified nitrile rubber prepared in Comparative Examples <NUM>-<NUM>, the elongation at break of the functionalized graphene oxide modified nitrile rubber prepared in Example <NUM> of the present invention is lower, the Shore hardness is higher, and the compression set at <NUM> is smaller, indicating that the functionalized graphene oxide modified nitrile rubber prepared in the embodiment of the present invention has good mechanical properties, small compression set, and good applicability to high temperature environments.

Claim 1:
A functionalized graphene oxide nitrile rubber mixture, comprising the following components in parts by weight: <NUM>-<NUM> parts of nitrile rubber, <NUM>-<NUM> parts of functionalized graphene oxide nitrile rubber masterbatch, <NUM>-<NUM> parts of vulcanizing agent, <NUM>-<NUM> parts of vulcanization accelerator, <NUM>-<NUM> parts of vulcanization activator, <NUM>-<NUM> parts of plasticizer, <NUM>-<NUM> parts of antioxidant, <NUM>-<NUM> parts of filler, <NUM>-<NUM> part of curing agent and <NUM>-<NUM> parts of dichlorophenol;
wherein the filler is a mixture of gas-mixture carbon black, semi-reinforcing furnace black and epoxy resin with a mass ratio of <NUM>-<NUM> : <NUM>-<NUM> : <NUM>-<NUM>, wherein the epoxy resin has an average epoxy value of <NUM>/<NUM>;
wherein a mass fraction of functionalized graphene oxide in the functionalized graphene oxide nitrile rubber masterbatch is <NUM>-<NUM>%;
wherein the functionalized graphene oxide nitrile rubber masterbatch is prepared by the following steps: dispersing a functionalized graphene oxide in a dispersant; ultrasonically dispersing for <NUM>-<NUM> minutes to obtain a functionalized graphene oxide dispersion; adding nitrile rubber latex and stirring for <NUM>-<NUM> to obtain a mixed solution, wherein the mass of the functionalized graphene oxide accounts for <NUM>-<NUM>% of the mass of the mixed solution; adding the mixed solution to coagulation solution for demulsification, wherein the coagulation solution is a mixed liquid of a calcium chloride aqueous solution and ethanol with a volume ratio of <NUM>:<NUM>-<NUM>, wherein the volume ratio of the mixed solution to the coagulation solution is <NUM>-<NUM>:<NUM>-<NUM>; after suction filtration, washing and drying, obtaining the functionalized graphene oxide nitrile rubber masterbatch;
wherein the functionalized graphene oxide is prepared by the following steps: preparing graphene oxide by a modified Hummers method; adding the graphene oxide and <NUM>-Aminopropyltrimethoxysilane as a modifier with a mass ratio of <NUM>:<NUM> into an anhydrous ethanol and ultrasonic stirring uniformly; heating to <NUM>-<NUM> in a water bath and refluxing for <NUM>-<NUM> hours; then adding distilled water to the mixture, centrifuging, washing and drying, so as to obtain Aminated Graphene.