Method for preparing ball seat material for automobile guide ball pin
Technical Field
The invention belongs to the field of automobile materials; to a method of preparing a material for an automotive guide ball pin; and more particularly, to a method of preparing a tee material for a guide ball pin of an automobile.
Background
The guide ball pin is an important part on the automobile and is used for controlling the steering of the automobile. Long-time, the structure of direction ball round pin is comparatively complicated, needs the form fit through ball seat and cylindrical casing just can rotate, and operation and equipment convenience are poor, have improved the processing cost of car to a certain extent. In addition, the structure is complex, so that the guide ball pin is worn seriously under long-term tensile and pressure load bearing, the service life is short, and the reliability requirement of long-term use is difficult to meet.
The inventor uses PET polyester as synthetic resin to form a small ball seat in Chinese utility model CN200820165818, and replaces the original steel wire small ball. The material has better elasticity, has larger matching surface, increases the friction surface, plays a role in compensating the abrasion of the product, and has excellent rotation performance and tensile pressure.
However, the use of PET polyester as a material for ball seats of guide ball pins for automobiles has disadvantages of low notched impact strength and low elongation at break.
To ameliorate these technical deficiencies, polycarbonate has further been alloyed with PET polyester. By virtue of the advantages of the amorphous polycarbonate polymer, the alloy formed by the amorphous polycarbonate polymer has excellent impact resistance and dimensional stability. Zengbanlu et al (polymer materials science and engineering, 1991, 110-.
Because PET polyester is a crystalline polymer and polycarbonate is an amorphous polymer, a simple blending system formed by the PET polyester and the polycarbonate is easy to generate phase separation, the bonding force of a two-phase interface is poor, and the notch impact strength is difficult to improve.
Therefore, there is an urgent need for further research on a method for preparing a ball seat material for a guide ball pin of an automobile based on the prior art.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a method for preparing a ball seat material with high notch impact strength and high elongation at break for an automobile guide ball pin.
To achieve the above objects, in one aspect, the present invention provides a method of preparing a tee material for a guide ball pin of an automobile, the method comprising the steps of:
the nano-scale alumina powder is modified by glycidyl methacrylate and a silane coupling agent to obtain alumina particles;
blending and modifying PET polyester and the alumina particles to obtain PET polyester modified by the alumina particles;
the polycarbonate and the PET polyester modified by the alumina particles are melted and blended to form a ball seat material;
the ball seat material is injection molded to form a ball seat for an automobile guide ball pin.
According to the method of the invention, the alumina particles are selected from nano-sized alumina particles.
In the present invention, the nano-scale means a particle size range having an average particle size of 1 to 1000 nm. Preferably, nanoscale means a particle size range having an average particle size of 10 to 900 nm; more preferably, nanoscale means a particle size range having an average particle size of 50 to 700 nm; and, most preferably, nanoscale means a particle size range having an average particle size of 100-500 nm.
In a particular embodiment, the nanoscale alumina is selected from alumina powders having an average particle size of 320 nm.
The method of the invention, wherein the weight ratio of the polycarbonate to the alumina particle modified PET polyester is (60-80): (40-20).
Preferably, the weight ratio of the polycarbonate to the alumina particle modified PET polyester is (65-75): (40-25); more preferably, the weight ratio of the polycarbonate to the alumina particle modified PET polyester is (60-75): (40-25); and, most preferably, the weight ratio of the polycarbonate to the alumina particle modified PET polyester is (60-70): (40-30).
In a specific embodiment, the weight ratio of the polycarbonate to the alumina particle modified PET polyester is 65: 35.
the method according to the invention, wherein the polycarbonate has a number average molecular weight Mn of 14000 and 30000 daltons.
Preferably, the number average molecular weight Mn of the polycarbonate is 16000 and 28000 daltons; more preferably, the number average molecular weight Mn of the polycarbonate is 18000 and 26000 daltons; and, most preferably, the number average molecular weight Mn of the polycarbonate is 20000-.
In a specific embodiment, the polycarbonate has a number average molecular weight Mn of 22000 daltons.
The method of the invention, wherein the number average molecular weight Mn of the PET polyester is 30000-46000 daltons.
Preferably, the number average molecular weight Mn of the PET polyester is 32000-44000 dalton; more preferably, the number average molecular weight Mn of the PET polyester is 34000 and 42000 daltons; and, most preferably, the number average molecular weight Mn of the PET polyester is 36000-40000 Dalton.
In a particular embodiment, the PET polyester has a number average molecular weight Mn of 38500 daltons.
The method of the present invention, wherein the glycidyl methacrylate is obtained from Shandong Yukang chemical Co., Ltd, and has a purity of 99.9%.
The method according to the present invention, wherein the silane coupling agent is a silane coupling agent having a polymerizable group.
Preferably, the polymerizable group is selected from the group consisting of vinyl, ethynyl, epoxy, and (meth) acryloxy; more preferably, the polymerizable group is selected from vinyl and (meth) acryloxy; and, most preferably, the polymerizable group is selected from (meth) acryloxy groups.
In a specific embodiment, the silane coupling agent is a silane coupling agent having a methacryloxypropyl group.
In a more specific embodiment, the silane coupling agent is selected from the group consisting of KH-570, 99.8% purity; purchased from Nanjing to the front chemical Co.
The method of the invention, wherein the weight ratio of the nanoscale alumina powder, the silane coupling agent and the glycidyl methacrylate is 10: (3-9): (4-15).
Preferably, the weight ratio of the nanoscale alumina powder, the silane coupling agent and the glycidyl methacrylate is 10: (3-8): (5-14); more preferably, the weight ratio of the nanoscale alumina powder, the silane coupling agent and the glycidyl methacrylate is 10: (4-7): (5-13); and, most preferably, the weight ratio of the nanoscale alumina powder, the silane coupling agent, and the glycidyl methacrylate is 10: (4-6): (6-12).
In a specific embodiment, the weight ratio of the nanoscale alumina powder, the silane coupling agent, and the glycidyl methacrylate is 10: 5: 10.
the method according to the invention, wherein the weight ratio of the alumina particles to the PET polyester is 1: (2-8).
Preferably, the weight ratio of the alumina particles to the PET polyester is 1: (3-7); more preferably, the weight ratio of the alumina particles to the PET polyester is 1: (3.5-6.5); and, most preferably, the weight ratio of the alumina particles to the PET polyester is 1: (4-6).
In a specific embodiment, the weight ratio of the alumina particles to the PET polyester is 1: 5.
advantageously, the process according to the invention is carried out by means of a twin-screw extruder.
In another aspect, the present invention provides a tee material obtained using the above method.
The inventor finds that the alloy material obtained by using the modified PET polyester obtained by modifying nano-alumina particles and polycarbonate has high impact strength and high elongation at break. Without wishing to be bound by any theory, the modified nano-alumina particles used in the invention not only play a role of the filler in improving the toughness of the ball seat material, but also promote the compatibility with the resin system through the reactivity of methacryloxypropyl on the surface of the alumina, and further improve the notch impact strength and the elongation at break of the ball seat material.
Compared with the prior art, the invention has the following beneficial technical effects:
i) the product obtained by the method has excellent notch impact strength and elongation at break, and the notch impact strength is more than or equal to 50KJ × m-2And the elongation at break is more than or equal to 130 percent; so that the performance requirement of the ball seat for the automobile guide ball pin can be fully met.
ii) the method of the invention is simple and easy to implement, easy to popularize and has higher practical value.
Detailed Description
In a specific embodiment of the invention, the notched impact strength test is performed according to ASTM D256-2018, the impact energy is 2.8J, and the test specimens from test group 5 are averaged.
Elongation at break tests were performed according to ASTM D638-2014, with a tensile rate of 10mm/min, a test temperature of room temperature, and an average of 5 test specimens tested.
The TGA test was carried out using a Q500 thermogravimetric analyzer of TA, with a temperature rise rate of 10 degrees/min from room temperature to 700 degrees under a nitrogen atmosphere.
The grafting rate of the modified nanoscale alumina was obtained from the TGA data.
Example 1:
10g of nano-sized alumina powder (average particle size: 320nm) and 5g of silane coupling agent KH570 were ultrasonically dispersed in toluene, reacted with stirring at 120 ℃ for 4 hours in a nitrogen atmosphere, and then cooled to room temperature. 8g of glycidyl methacrylate dissolved in toluene and a few drops of AIBN were added and the reaction was stirred at 80 ℃ for 2 hours under a nitrogen atmosphere. After centrifugal drying, acetone extraction is used for removing unreacted coupling agent and residual toluene solvent, finally drying is carried out, modified nanometer alumina particles are obtained, and the grafting rate of glycidyl methacrylate obtained by TGA data is 13.8 wt%.
Preheating 8g of modified nano-alumina particles at 90 ℃, adding the modified nano-alumina particles into 40g of PET polyester preheated and melted at 90 ℃, and stirring the PET polyester under vacuum for 2.5h to ensure that the modified PET polyester is uniformly mixed with the PET polyester, wherein the number average molecular weight Mn of the PET polyester is 38500 daltons.
65g of polycarbonate (the number average molecular weight Mn is 22000 dalton) and 35g of modified PET polyester are uniformly mixed, and then the mixture is added into a double-screw extruder to be extruded and granulated, wherein the extrusion processing temperature is controlled between 240 +/-2 ℃, and the rotation speed of a screw is 400 rpm. Then, the extruded and cut granules are dried at 120 ℃ and prepared into samples.
Example 2:
10g of nano-sized alumina powder (average particle size: 320nm) and 6g of silane coupling agent KH570 were ultrasonically dispersed in toluene, reacted with stirring at 130 ℃ for 6 hours in a nitrogen atmosphere, and then cooled to room temperature. 12g of glycidyl methacrylate dissolved in toluene and a few drops of AIBN were added and the reaction was stirred at 80 ℃ for 2 hours under a nitrogen atmosphere. After centrifugal drying, acetone extraction is used for removing unreacted coupling agent and residual toluene solvent, finally drying is carried out, modified nanometer alumina particles are obtained, and the grafting rate of glycidyl methacrylate obtained by TGA data is 15.4 wt%.
Preheating 10g of modified nano-alumina particles at 90 ℃, adding the particles into 40g of PET polyester preheated and melted at 90 ℃, and stirring the particles for 3h in vacuum, wherein the number average molecular weight Mn of the PET polyester is 38500 daltons, so that the modified PET polyester is obtained by uniformly mixing the particles and the PET polyester.
70g of polycarbonate (the number average molecular weight Mn is 22000 dalton) and 30g of modified PET polyester are uniformly mixed, and then the mixture is added into a double-screw extruder to be extruded and granulated, wherein the extrusion processing temperature is controlled between 230 +/-2 ℃, and the screw rotating speed is 600 rpm. Then, the extruded and cut granules are dried at 110 ℃ and prepared into samples.
Example 3:
10g of nano-sized alumina powder (average particle size: 320nm) and 4g of silane coupling agent KH570 were ultrasonically dispersed in toluene, reacted with stirring at 125 ℃ for 3 hours in a nitrogen atmosphere, and then cooled to room temperature. 6g of glycidyl methacrylate dissolved in toluene and a few drops of AIBN were added and the reaction was stirred at 80 ℃ for 2 hours under a nitrogen atmosphere. After centrifugal drying, acetone extraction is used for removing unreacted coupling agent and residual toluene solvent, finally drying is carried out, modified nanometer alumina particles are obtained, and the grafting rate of glycidyl methacrylate obtained by TGA data is 11.3 wt%.
Preheating 7g of modified nano-alumina particles at 90 ℃, adding the modified nano-alumina particles into 42g of PET polyester preheated and melted at 90 ℃, stirring the PET polyester under vacuum for 4 hours to ensure that the modified PET polyester is uniformly mixed with the PET polyester, wherein the number average molecular weight Mn of the PET polyester is 38500 daltons.
60g of polycarbonate (the number average molecular weight Mn is 22000 dalton) and 40g of modified PET polyester are uniformly mixed, and then the mixture is added into a double-screw extruder to be extruded and granulated, wherein the extrusion processing temperature is controlled between 250 +/-2 ℃, and the rotation speed of the screw is 600 rpm. The extruded and cut pellets were then dried at 130 ℃ and prepared into samples.
Comparative example 1:
the remaining conditions were the same as in example 1, but unmodified nanosize alumina powder was used directly.
Comparative example 2:
the same procedure as in example 1 was repeated except that 10g of nanosized alumina powder (average particle diameter: 320nm), 1g of silane coupling agent KH570 and 2g of glycidyl methacrylate were used to obtain modified nanosized alumina particles having a glycidyl methacrylate graft ratio of 6.9 wt%.
Comparative example 3:
the same procedure as in example 1 was repeated except that 10g of nano-alumina (average particle diameter: 320nm), 0.5g of KH570 as a silane coupling agent, and 1g of glycidyl methacrylate were used to obtain modified nano-alumina particles having a glycidyl methacrylate graft ratio of 3.7 wt%.
The notched impact strength and elongation at break of the test specimens of examples 1-3 and comparative examples 1-3 according to the test methods described above are shown in Table 1 with the results associated therewith:
TABLE 1
As can be seen from Table 1, the alloy materials obtained from the modified PET polyester obtained from the modified nanoscale alumina particles and the polycarbonate by the methods of examples 1-3 of the present invention have not only higher impact strength but also higher elongation at break. Correlation index (notch impact strength is more than or equal to 50KJ m)-2And the elongation at break is more than or equal to 130 percent) so that the ball seat can fully meet the performance requirements of the ball seat for the automobile guide ball pin.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.