the following examples are used for illustrating the invention , but not limiting the scope of the invention . the amounts of materials added in the following reactions are represented by molar parts , unless specified otherwise . for the contents not specified , such as the addition amount of a solvent , the addition amount of a catalyst or the like , they are deemed as the traditional operations in the field . in the above reaction scheme , r 1 is a c1 - c10 perfluoroalkyl ; r 2 is a substituted or unsubstituted group selected from a phenyl group , a benzyl group , a benzo - heterocyclic group or a naphthyl group ; n is 3 - 35 , preferably 4 - 30 , and more preferably 5 - 15 . wherein , in the substituted r 2 group , the substituent is a c1 - c5 alkyl group , a c2 - c5 alkenyl group , a c1 - c5 alkoxy group or a halogen atom . preferably , r 1 is a c1 - c5 perfluoroalkyl group ; and r 2 is a phenyl group , a benzodihydropyranyl group or a naphthyl group . ( 1 ) into a clean three - necked flask equipped with a thermometer , a condenser and a constant pressure dropping funnel , 5 . 2 parts of a perfluoroalkyl acyl fluoride r 1 cof , 0 . 8 part of concentrated hcl are added in turn , and 5 . 8 parts of methanol is slowly added dropwise under magnetic stirring . after the addition , the mixture is allowed to react under reflow at about 120 ° c . overnight . the reaction is stopped and cooled to room temperature . the ph of the mixture is adjusted to about 7 . 0 with a 0 . 5 mol / l koh solution . layers are separated with a funnel , and the organic phase is extracted with methanol , washed with an aqueous saturated nacl solution , and dried over anhydrous sodium sulfate to obtain a light yellow oil liquid , that is , the compound 1 . ( 2 ) 5 parts of the compound 1 is placed into a clean three - necked flask , and 12 . 3 parts of methanol and 51 parts of a koh solution with a concentration of 4 mol / l are added thereto . the mixture is heated to 85 ° c . under magnetic stirring and refluxed for about 38 hrs , and then subjected to reduced pressure distillation so as to remove methanol . after cooling to room temperature , the solution is acidified by adding 1 . 2 mol / l hydrochloric acid solution and extracted with ethyl acetate . the organic phases are combined , washed with an aqueous saturated nacl solution , dried over anhydrous sodium sulfate and filtered so as to obtain a white crystal , that is , the compound 2 . ( 3 ) into a clean three - necked flask equipped with a thermometer , a condenser and a water segregator , 1 . 1 parts of the compound 2 , 5 parts of polyethylene glycol ( peg ) and xylene solvent are added in turn , and a catalytic amount of p - toluene sulfonic acid is added as a catalyst . the mixture is heated to 105 ° c . under magnetic stirring and reacted until there is no water produced in the water segregator . after the reaction , the xylene solvent is removed by reduced pressure distillation and the mixture is cooled to room temperature . the organic phase is washed with a saturated sodium carbonate solution to remove the un - reacted raw materials and the p - toluene sulfonic acid catalyst . then , the product is dissolved in tetrahydrofuran , subjected to suction filtration to remove residual sodium carbonate . the product is subjected to reduced pressure distillation to remove tetrahydrofuran and vacuum dried to obtain the product 3 . ( 4 ) 1 part of the product 3 and 1 . 5 parts of the compound 4 are placed into a clean three - necked flask equipped with a thermometer , a condenser and a water segregator , xylene as a solvent and a catalytic amount of p - toluene sulfonic acid as a catalyst are added . the mixture is heated to about 105 ° c . under magnetic stirring and reacted until there is no water produced in the water segregator . after the reaction , the xylene solvent is removed by reduced pressure distillation and the mixture is cooled to room temperature . the organic phase is washed with a saturated sodium carbonate solution to remove the un - reacted raw materials and the p - toluene sulfonic acid catalyst . then , the product is dissolved in tetrahydrofuran , subjected to suction filtration to remove the residual sodium carbonate . the resultant product is subjected to reduced pressure distillation to remove tetrahydrofuran and vacuum dried to obtain the product 5 , that is , the fluorine - containing polymer as represented by general formula ( i ). the fluorine - containing polymer 1 is prepared according to the above process , wherein the original reactant is perfluoroethyl acyl fluoride , the polyethylene glycol is peg400 , and the compound 4 is benzoic acid . in the obtained fluorine - containing polymer 1 , r 1 is perfluoroethyl , r 2 is phenyl , and n is 8 - 11 . the proton assignment and chemical shift values in nuclear magnetic resonance spectroscopy ( cdcl 3 , 300 mhz ) are shown as follows . the fluorine - containing polymer 2 is prepared according to the above process , wherein the original reactant is perfluoroethyl acyl fluoride , the polyethylene glycol is peg400 , and the compound 4 is 2h - benzopyran - 3 - carboxylic acid . in the obtained fluorine - containing polymer 2 , r 1 is perfluoroethyl , r 2 is benzodihydropyranyl , and n is 8 - 11 . the proton assignment and chemical shift values in nuclear magnetic resonance spectroscopy ( cdcl 3 , 300 mhz ) are shown as follows . the fluorine - containing polymer 3 is prepared according to the above process , wherein the original reactant is perfluoroethyl acyl fluoride , the polyethylene glycol is peg400 , and the compound 4 is 2 - naphthalenecarboxylic acid . in the obtained fluorine - containing polymer 3 , r 1 is perfluoroethyl , r 2 is 2 - naphthyl , and n is 8 - 11 . the proton assignment and chemical shift values in nuclear magnetic resonance spectroscopy ( cdcl 3 , 300 mhz ) are shown as follows . the fluorine - containing polymer 4 is prepared according to the above process , wherein the original reactant is perfluoroethyl acyl fluoride , the polyethylene glycol is peg200 , and the compound 4 is benzoic acid . in the obtained fluorine - containing polymer 4 , r 1 is perfluoroethyl , r 2 is phenyl group , and n is 4 - 6 . the proton assignment and chemical shift values in nuclear magnetic resonance spectroscopy ( cdcl 3 , 300 mhz ) are shown as follows . the fluorine - containing polymer 5 is prepared according to the above process , wherein the original reactant is perfluoroethyl acyl fluoride , the polyethylene glycol is peg400 , and the compound 4 is p - vinyl benzoic acid . in the obtained fluorine - containing polymer 5 , r 1 is perfluoroethyl , r 2 is p - vinyl phenyl , and n is 8 - 11 . the proton assignment and chemical shift values in nuclear magnetic resonance spectroscopy ( cdcl 3 , 300 mhz ) are shown as follows . the fluorine - containing polymer 6 is prepared according to the above process , wherein the original reactant is perfluoroethyl acyl fluoride , the polyethylene glycol is peg600 , and the compound 4 is p - methyl benzoic acid . in the obtained fluorine - containing polymer 6 , r 1 is perfluoroethyl , r 2 is p - methyl phenyl , and n is 13 - 15 . the proton assignment and chemical shift values in nuclear magnetic resonance spectroscopy ( cdcl 3 , 300 mhz ) are shown as follows . the fluorine - containing polymer 7 is prepared according to the above process , wherein the original reactant is perfluoroethyl acyl fluoride , the polyethylene glycol is peg1000 , and the compound 4 is 2h - benzopyran - 3 - carboxylic acid . in the obtained fluorine - containing polymer 7 , r 1 is perfluoroethyl , r 2 is benzodihydropyranyl , and n is 20 - 23 . the proton assignment and chemical shift values in nuclear magnetic resonance spectroscopy ( cdcl 3 , 300 mhz ) are shown as follows . the fluorine - containing polymer 8 is prepared according to the above process , wherein the original reactant is perfluoroethyl acyl fluoride , the polyethylene glycol is peg600 , and the compound 4 is 2h - 5 - chloro - benzopyran - 3 - carboxylic acid . in the obtained fluorine - containing polymer 8 , r 1 is perfluoroethyl , r 2 is 5 - chloro - benzodihydropyranyl , and n is 13 - 15 . the proton assignment and chemical shift values in nuclear magnetic resonance spectroscopy ( cdcl 3 , 300 mhz ) are shown as follows . the fluorine - containing polymer 9 is prepared according to the above process , wherein the original reactant is perfluoroethyl acyl fluoride , the polyethylene glycol is peg1500 , and the compound 4 is 2 - naphthalenecarboxylic acid . in the obtained fluorine - containing polymer 9 , r 1 is perfluoroethyl , r 2 is 2 - naphthyl , and n is 25 - 30 . the proton assignment and chemical shift values in nuclear magnetic resonance spectroscopy ( cdcl 3 , 300 mhz ) are shown as follows . the fluorine - containing polymer 10 is prepared according to the above process , wherein the original reactant is perfluoroethyl acyl fluoride , the polyethylene glycol is peg600 , and the compound 4 is 6 - acetyl - 2 - naphthalenecarboxylic acid . in the obtained fluorine - containing polymer 10 , r 1 is perfluoroethyl , r 2 is 6 - acetyl - 2 - naphthyl , and n is 13 - 15 . the proton assignment and chemical shift values in nuclear magnetic resonance spectroscopy ( cdcl 3 , 300 mhz ) are shown as follows . into a clean feed cylinder , 3 parts by weight of propylene glycol methyl ether acetate solvent was added , and then 0 . 5 part by weight of solsperse 24000 dispersant , 0 . 2 part by weight of a a81 resin ( laropal a 81 , guangzhou jinhong chemical co ., ltd ), 0 . 05 part by weight of a solsperse 12000 pigment intensifier were added into the feed cylinder in turn . the mixture was stirred under a rotating rate of 3000 rpm for about 40 min . then , the obtained mixture was added with 1 part of g58 pigment ( dic company ) ( cas number : 728018 - 63 - 1 ) and 0 . 05 part by weight of fc4430 fluorine carbon surfactant ( 3m company ), and stirred under a rotating rate of 3000 rpm for about 30 min to obtain a pigment mixture . the pigment mixture obtained in the pre - dispersion stage was loaded into a sand mill , grinded under a rotating rate of 500 rpm for 10 min firstly , then grinded under a rotating rate of 2000 rpm for about 5 hours ; after that , the mixture was further grained under a reduced rotating rate of 400 rpm for about 15 min . after the sand grinding , the obtained pigment dispersion was discharged from the sand mill . the changes of the viscosity and particle diameter of the pigment particles in the pigment dispersion with the lapse of time were checked , and the bottom of the container was observed visually to see whether there was any precipitate produced . the method for this evaluation comprised observing the changes of the viscosity and particle diameter with the lapse of time at normal temperature ( 25 ° c .) and at 41 ° c . the evaluating results for the pigment dispersion in example 1 were shown in table 1 . the relation between the changes of the viscosity and particle diameter of the pigment particles in the above pigment dispersion and the lapse of time were shown in fig1 and 2 . from the results in table 1 and fig1 and 2 , it can be seen that when fc4430 fluorine carbon surfactant was added during the pre - dispersion stage , the changes of the viscosity and particle diameter of the obtained pigment particles were all very small , and there was no precipitate produced , and thus , the stability of the pigment dispersion was improved significantly . the steps in example 1 were repeated expect that the surfactant fc4430 was not added . the evaluating results for the pigment dispersion obtained in comparative example 1 were shown in table 2 . the relation between the changes of the particle diameter of the pigment particles in the above pigment dispersion and the lapse of time was shown in fig3 . from the results in table 2 and fig3 , it can be seen that when a surfactant was not added , the particle diameter in the pigment dispersion upon discharging could reach about 50 nm . however , after one day , the particle diameter increased quickly and reached 100 nm or more in one week . the viscosity also increased continuously and after one month , the pigment dispersion became a state of flocculation . the stability of the pigment dispersion was very poor . the steps in example 1 were repeated expect that the surfactant fc4430 was not added during the pre - dispersion stage , instead , it was added about one hour after the beginning of the grinding step . the evaluating results for the pigment dispersion obtained in comparative example 1 were shown in table 3 . the relation between the changes of the particle diameter of the pigment particles in the above pigment dispersion and the lapse of time was shown in fig4 . from the results in table 3 and fig4 , it can be seen that when the surfactant was added during the grinding stage , the change degree of the pigment particle diameter and viscosity with the lapse of time in one week became smaller , which was better than the case in comparative example 1 where fc4430 was not added . however , the changes increased continuously and more quickly with the lapse of time . in one week , a lot of precipitates occurred on the bottom of the container , and increased continuously . thus , it can be seen that the stability of the pigment dispersion was inferior . the steps in example 1 were repeated expect that the surfactant fc4430 was not added during the pre - dispersion stage and the grinding stage , instead , fc4430 was added alone after the grinding stage , and then the mixture was stirred at a rotating rate of about 500 rpm for about 10 min to mix it uniformly . the evaluating results for the pigment dispersion obtained in comparative example 3 were shown in table 4 . the relation between the changes of particle diameter of pigment particles in the above pigment dispersion and the lapse of time was shown in fig5 . from the results in table 4 and fig5 , it can be seen that when the surfactant was added after the grinding stage , the change degree of the pigment particle diameter and viscosity in one week with the lapse of time became smaller , which was better than the case in comparative example 1 where fc4430 was not added . however , the changes of the pigment particle diameter and viscosity increased continuously and more quickly with the lapse of time . in one week , a little precipitate occurred on the bottom of the container , and it increased continuously , but the amount of the precipitate was obviously less than that in comparative example 1 . thus , it can be seen that the stability of the pigment dispersion was still inferior . from the results of example 1 and comparative examples 1 - 3 , it can be seen that when the surfactant fc4430 was added into the pigment dispersion , the effect of stabilization would be better than the case where fc4430 was not added . however , the addition timing of the surfactant had large influence on the effect of stabilization . when a certain amount of a fluorine - containing polymer was added during the pre - dispersion stage , the changes of the particle diameter and viscosity of pigment particles in the obtained pigment dispersion with the lapse of time became very small and there was no precipitate produced . thus , the stability of the pigment dispersion was improved significantly . into a clean feed cylinder , 4 parts by weight of propylene glycol diacetate solvent was added , and then 0 . 4 part by weight of byk 21324 dispersant , 0 . 1 part by weight of a81 resin , 0 . 05 part by weight of byk 2105 pigment intensifier were add into the feed cylinder in turn . the mixture was stirred under a rotating rate of 3000 rpm for about 40 min . then , the obtained mixture was added with 1 part by weight of g58 pigment and 0 . 03 part of fluorine - containing polymer 1 , and stirred under a rotating rate of 3000 rpm for about 30 min to obtain a pigment mixture . the process in the grinding was the same as that in example 1 . the evaluating results ( according to the same method as mentioned in example 1 ) for the pigment dispersion in example 2 were shown in table 5 . the relation between the changes of the viscosity and particle diameter of the pigment particles in the above pigment dispersion and the lapse of time were shown in fig6 and 7 . from the results in table 5 and fig6 and 7 , it can be seen that when fluorine - containing polymer 1 as a fluorine carbon surfactant was added during the pre - dispersion stage , the changes of the viscosity and particle diameter of the obtained pigment particles were all very small , and there was no precipitate produced , and thus , the stability of the pigment dispersion was improved significantly . the steps in example 2 were repeated expect that the fluorine - containing polymer 1 as a fluorine carbon surfactant was not added . the evaluating results for the pigment dispersion in comparative example 4 were shown in table 6 . the relation between the changes of the particle diameter of the pigment particles in the above pigment dispersion and the lapse of time was shown in fig8 . from the results in table 6 and fig8 , it can be seen that when the surfactant was not added , the particle diameter in the pigment dispersion upon discharging could reach about 47 nm . however , after one day , the particle diameter increased quickly and reached near 100 nm in one week . the viscosity also increased continuously and after one week , viscosity of the pigment dispersion became about 30 cps . after one month , the pigment dispersion became a state of flocculation . the stability of the pigment dispersion was very poor . the steps in example 2 were repeated expect that the fluorine - containing polymer 1 as a fluorine carbon surfactant was not added during the pre - dispersion stage , instead , it was added about one hour after the beginning of the grinding step . the evaluating results for the pigment dispersion in comparative example 5 were shown in table 7 . the relation between the changes of the particle diameter of the pigment particles in the above pigment dispersion and the lapse of time was shown in fig9 . from the results in table 7 and fig9 , it can be seen that when the surfactant was added during the grinding stage , the change degree of the pigment particle diameter and viscosity with the lapse of time in one week became smaller , which was better than the case in comparative example 4 where the surfactant was not added . but the change of viscosity was relatively large , and increased continuously and more quickly with the lapse of time . there was no precipitate occurred on the bottom of the container in one week , but a little sand like precipitate occurred on the bottom of the container after one week . thus , it can be seen that the stability of the pigment dispersion was inferior . the steps in example 2 were repeated expect that the fluorine - containing polymer 1 as a fluorine carbon surfactant was not added during the pre - dispersion stage and the grinding stage , instead , the fluorine - containing polymer 1 was added alone after the grinding stage , and then the mixture was stirred at a rotating rate of about 500 rpm for about 10 min to mix it uniformly . the evaluating results for the pigment dispersion in comparative example 6 were shown in table 8 . the relation between the change of particle diameter of pigment particles in the above pigment dispersion and the lapse of time was shown in fig1 . from the results in table 8 and fig1 , it can be seen that when the surfactant was added after the grinding stage , the change degree of the pigment particle diameter and viscosity with the lapse of time in one week became smaller , which was better than comparative example 4 where the surfactant was not added . however , the pigment particle diameter and viscosity still increased continuously and more quickly with the lapse of time . in one week , a little precipitate occurred on the bottom of the container , and it increased continuously , but the amount of the precipitate was obviously less than that in comparative example 4 . thus , it can be seen that the stability of the pigment dispersion was still inferior . from the results in example 2 and comparative examples 4 - 6 , it can be seen that when a certain amount of the fluorine - containing polymer according to the invention was added as a fluorine carbon surfactant during the pre - dispersion stage , the changes of the particle diameter and viscosity of the pigment particles in the obtained pigment dispersion with the lapse of time would become very small and there was no precipitate produced . thus , the stability of the pigment dispersion was improved significantly . into a clean feed cylinder , 3 parts by weight of ethyl 3 - ethoxylpropionate solvent was added , and then 0 . 5 part by weight of solsperse 32000 dispersant , 0 . 15 part by weight of a81 resin , 0 . 05 part by weight of solsperse 22000 pigment intensifier were add into the feed cylinder in turn . the mixture was stirred under a rotating rate of 3000 rpm for about 40 min . then , the obtained mixture was added with 1 part by weight of g58 pigment and 0 . 08 part by weight of fluorine - containing polymer 2 , and stirred under a rotating rate of 3000 rpm for about 30 min to obtain a pigment mixture . the process in the grinding was the same as that in example 1 . the evaluating results ( according to the same method as mentioned in example 1 ) for the pigment dispersion in example 3 were shown in table 9 . the relation between the changes of the viscosity and particle diameter of the pigment particles in the above pigment dispersion and the lapse of time were shown in fig1 and 12 . from the results in table 9 and fig1 and 12 , it can be seen that when the fluorine - containing polymer 2 as a fluorine carbon surfactant was added during the pre - dispersion stage , the changes of the viscosity and particle diameter of the obtained pigment particles were all very small , and there was no precipitate produced , and thus , the stability of the pigment dispersion was improved significantly . the steps in example 3 were repeated expect that the fluorine - containing polymer 2 as a fluorine carbon surfactant was not added . the evaluating results for the pigment dispersion obtained in comparative example 7 were shown in table 10 . the relation between the changes of the particle diameter of the pigment particles in the above pigment dispersion and the lapse of time was shown in fig1 . from the results in table 10 and fig1 , it can be seen that when the surfactant was not added , the particle diameter in the pigment dispersion upon discharging could reach about 47 nm . however , after one day , the particle diameter increased quickly and reached near 80 nm in one week . the viscosity also increased continuously and after one week , viscosity of the pigment dispersion became about 30 cps . after one month , the pigment dispersion became a state of flocculation . the stability of the pigment dispersion was very poor . the steps in example 3 were repeated expect that the fluorine - containing polymer 2 as a fluorine carbon surfactant was not added during the pre - dispersion stage , instead , it was added about one hour after the beginning of the grinding step . the evaluating results for the pigment dispersion obtained in comparative example 8 were shown in table 11 . the relation between the changes of the particle diameter of the pigment particles in the above pigment dispersion and the lapse of time was shown in fig1 . from the results in table 11 and fig1 , it can be seen that when the surfactant was added during the grinding stage , the change degree of the pigment particle diameter and viscosity with the lapse of time in one week became smaller , which was better than comparative example 7 where the surfactant was not added . but the change of viscosity was relatively large , and increased continuously and more quickly with the lapse of time . there was no precipitate occurred on the bottom of the container in one week , but a little sand like precipitate occurred on the bottom of the container after one week . thus , it can be seen that the stability of the pigment dispersion was inferior . the steps in example 3 were repeated expect that the fluorine - containing polymer 2 as a fluorine carbon surfactant was not added during the pre - dispersion stage and the grinding stage , instead , the fluorine - containing polymer 2 was added alone after the grinding stage , and then the mixture was stirred at a rotating rate of about 500 rpm for about 10 min to mix it uniformly . the evaluating results for the pigment dispersion in comparative example 9were shown in table 12 . the relation between the change of the particle diameter of the pigment particles in the above pigment dispersion and the lapse of time was shown in fig1 . from the results in table 12 and fig1 , it can be seen that when the surfactant was added after the grinding stage , the change degree of the pigment particle diameter and viscosity with the lapse of time in one week became smaller , which was better than comparative example 7 where the surfactant was not added . however , the changes still increased continuously and more quickly with the lapse of time . in one week , a little precipitate occurred on the bottom of the container , and it increased continuously , but the amount of the precipitate was obviously less than that in comparative example 7 . thus , it can be seen that the stability of the pigment dispersion was still inferior . from the results in example 3 and comparative examples 7 - 9 , it can be seen that when a certain amount of the fluorine - containing polymer according to the invention was added as a fluorine carbon surfactant during the pre - dispersion stage , the changes of the particle diameter and viscosity of the pigment particles in the obtained pigment dispersion with the lapse of time would become very small and there was no precipitate produced . thus , the stability of the pigment dispersion was improved significantly . into a clean feed cylinder , 5 parts by weight of propylene glycol methyl ether acetate solvent was added , and then 0 . 3 part by weight of byk 21116 dispersant , 0 . 2 part by weight of a81 resin , 0 . 05 part by weight of byk 2100 pigment intensifier were add into the feed cylinder in turn . the mixture was stirred under a rotating rate of 3000 rpm for about 40 min then , the obtained mixture was added with 1 part by weight of g58 pigment and 0 . 10 part by weight of fluorine - containing polymer 3 , and stirred under a rotating rate of 3000 rpm for about 30 min to obtain a pigment mixture . the process in the grinding was the same as that in example 1 . the evaluating results ( according to the same method as mentioned in example 1 ) for the pigment dispersion in example 4 were shown in table 13 . the relation between the changes of the viscosity and particle diameter of the pigment particles in the above pigment dispersion and the lapse of time were shown in fig1 and 17 . from the results in table 13 and fig1 and 17 , it can be seen that when fluorine - containing polymer 3 as a fluorine carbon surfactant was added during the pre - dispersion stage , the changes of the viscosity and particle diameter of the obtained pigment particles were all very small , and there was no precipitate produced , and thus , the stability of the pigment dispersion was improved significantly . the steps in example 4 were repeated expect that the fluorine - containing polymer 3 as a fluorine carbon surfactant was not added . the evaluating results for the pigment dispersion obtained in comparative example 10 were shown in table 14 . the relation between the change of the particle diameter of the pigment particles in the above pigment dispersion and the lapse of time was shown in fig1 . from the results in table 10 and fig1 , it can be seen that when the surfactant was not added , the particle diameter in the pigment dispersion upon discharging could reach about 47 nm however , after one day , the particle diameter increased quickly and reached near 80 nm in one week . the viscosity also increased continuously and after one week , viscosity of the pigment dispersion became about 30 cps . after one month , the pigment dispersion became a state of flocculation . the stability of the pigment dispersion was very poor . the steps in example 4 were repeated expect that the fluorine - containing polymer 3 as a fluorine carbon surfactant was not added during the pre - dispersion stage , instead , it was added about one hour after the beginning of the grinding step . the evaluating results for the pigment dispersion obtained in comparative example 11 were shown in table 15 . the relation between the change of the particle diameter of the pigment particles in the above pigment dispersion and the lapse of time was shown in fig1 . from the results in table 15 and fig1 , it can be seen that when the surfactant was added during the grinding stage , the change degree of the pigment particle diameter and viscosity with the lapse of time in one week became smaller , which was better than comparative example 10 where the surfactant was not added . but the change of viscosity was relatively large , and increased continuously and more quickly with the lapse of time . there was no precipitate occurred on the bottom of the container in one week , but a little sand like precipitate occurred on the bottom of the container after one week . thus , it can be seen that the stability of the pigment dispersion was inferior . the steps in example 4 were repeated expect that the fluorine - containing polymer 3 as a fluorine carbon surfactant was not added during the pre - dispersion stage and the grinding stage , instead , the fluorine - containing polymer 3 was added alone after the grinding stage , and then the mixture was stirred at a rotating rate of about 500 rpm for about 10 min to mix it uniformly . the evaluating results for the pigment dispersion obtained in comparative example 12 were shown in table 16 . the relation between the change of the particle diameter of the pigment particles in the above pigment dispersion and the lapse of time was shown in fig2 . from the results in table 16 and fig2 , it can be seen that when the surfactant was added after the grinding stage , the change degree of the pigment particle diameter and viscosity with the lapse of time in one week became smaller , which was better than comparative example 10 where the surfactant was not added . however , the changes still increased continuously and more quickly with the lapse of time . in one week , a little precipitate occurred on the bottom of the container , and it increased continuously , but the amount of the precipitate was obviously less than that in comparative example 10 . thus , it can be seen that the stability of the pigment dispersion was still inferior . from the results in example 4 and comparative examples 11 - 12 , it can be seen that when a certain amount of the fluorine - containing polymer according to the invention was added as a fluorine carbon surfactant during the pre - dispersion stage , the changes of the particle diameter and viscosity of the pigment particles in the obtained pigment dispersion with the lapse of time would become very small and there was no precipitate produced . thus , the stability of the pigment dispersion was improved significantly . from the results in example 1 and examples 2 - 4 , it can be seen that the particle diameters of the pigment particles obtained examples 2 - 4 are relative smaller , and the viscosities thereof are also lower , and thus , the stabilization effect of the fluorine carbon surfactants prepared in examples 2 - 4 are better than that of the existing fluorine carbon surfactant . although the invention has been described in detail above by general description and specific embodiments , they can be modified or improved based on the invention , which is obvious for those skilled in the art . thus , these modification and improvement made without departing from the spirit of the invention all fall into the protection scope of the invention .