A method for preparing chlorinated polypropylene

Abstract

The invention discloses a preparation method of chlorinated polypropylene, belonging to the technical field of organic synthesis. The preparation method comprises the following steps: preparing modified calcium carbonate whiskers, preparing a foaming agent, preparing porous powdered polypropylene, preparing a Pickering emulsifier, and chlorinating; the preparation of the modified calcium carbonate whiskers comprises the following steps: preparing calcium carbonate whiskers and modifying them; the preparation of the Pickering emulsifier comprises the following steps: preparing hollow silica and modifying the surface; the preparation method of the invention can improve the reaction uniformity in the preparation, ensure that the polypropylene does not settle in the preparation, the prepared chlorinated polypropylene has high chlorination degree and good solubility in organic solvents, and can also avoid the use of carbon tetrachloride solvent.

Description

Technical Field

[0001] The invention relates to the technical field of organic synthesis, and in particular to a method for preparing chlorinated polypropylene. Background Art

[0002] Chlorinated polypropylene is a thermoplastic resin prepared by chlorination modification of polypropylene. It is widely used in the coating and adhesive industries. The finished product is a white or slightly yellow solid with excellent water resistance, acid resistance, alkali resistance, film-forming performance, high transparency, non-toxic and tasteless, and non-flammable. Chlorinated polypropylene is mainly used in inks, adhesives, and coatings. When used in inks, chlorinated polypropylene can improve the high temperature resistance and corrosion resistance of inks; when used in adhesives, chlorinated polypropylene can improve the high temperature resistance of adhesives; when used in coatings, chlorinated polypropylene can improve the corrosion resistance and heat resistance of coatings.

[0003] Commonly used methods for producing chlorinated polypropylene include solution method, solid phase method and suspension method. The solution method is to dissolve polypropylene in carbon tetrachloride solvent, and in the presence of an initiator, introduce chlorine gas to carry out chlorination reaction to prepare chlorinated polypropylene; the solid phase method is to introduce chlorine gas into powdered polypropylene in the presence of ultraviolet rays to carry out chlorination reaction to prepare chlorinated polypropylene; the suspension method is to disperse powdered polypropylene in water or hydrochloric acid through dispersants and emulsifiers, and in the presence of an initiator, carry out chlorination reaction through chlorine gas. Among them, the chlorination reaction in the solution method has good reaction uniformity, but the carbon tetrachloride solvent used will have a serious impact on the ozone layer in the atmosphere, resulting in restrictions on the solution method; the reaction temperature of the chlorination reaction in the solid phase method is high, and since it is difficult to achieve uniform dispersion between powdered polypropylene and chlorine gas, the reaction uniformity is poor, resulting in high energy consumption of the solid phase method, and the chlorine atoms in the chlorinated polypropylene produced by the solid phase method are unevenly distributed. Therefore, the suspension method has become the most promising production method.

[0004] However, the chlorination reaction in the suspension method is a gas-solid phase reaction between chlorine and powdered polypropylene. Although the powdered polypropylene is evenly dispersed by the dispersant, the powdered polypropylene has a solid structure and chlorine can only undergo a chlorination reaction with the polypropylene on its surface, resulting in poor reaction uniformity and a low degree of chlorination of the prepared chlorinated polypropylene.

[0005] In order to solve the above problems, the most commonly used method is to refine the powdered polypropylene, thereby increasing the specific surface area of ​​the powdered polypropylene, further improving the reaction uniformity of the chlorination reaction and the chlorination degree of the prepared chlorinated polypropylene. However, since the powdered polypropylene is still a solid structure, part of the polypropylene is still not chlorinated, and the chlorine atoms in the prepared chlorinated polypropylene are unevenly distributed in the molecular chain, resulting in poor solubility of the prepared chlorinated polypropylene in organic solvents, and the prepared solution is turbid after dissolution, further affecting the application effect of the chlorinated polypropylene in inks and adhesives. Although carbon tetrachloride solvent can be used to swell the polypropylene before chlorination to increase the contact area between the polypropylene and chlorine, there will be a problem of affecting the ozone layer in the atmosphere due to the use of carbon tetrachloride solvent.

[0006] In response to the above problems, the inventors tried to mix polypropylene with a pore-forming agent, and then melt, extrude, foam, granulate, crush, and sieve to prepare porous powdered polypropylene, and then prepare chlorinated polypropylene by a suspension method, so as to increase the specific surface area of ​​the powdered polypropylene, and further improve the reaction uniformity of the chlorination reaction and the chlorination degree of the prepared chlorinated polypropylene. However, when preparing chlorinated polypropylene, the following problems were found: First, the foaming agents used include azodicarbonamide foaming agent and inorganic foaming agent, but the azodicarbonamide foaming agent will have chemical residues during foaming, which adhere to the surface of the prepared porous powdered polypropylene, affecting the progress of the chlorination reaction, resulting in a decrease in the chlorination degree of the prepared chlorinated polypropylene and a deterioration in solubility in organic solvents; the inorganic foaming agent has poor compatibility with polypropylene, resulting in poor dispersibility of the inorganic foaming agent in polypropylene, and uneven distribution of pores in the porous powdered polypropylene, which further leads to a poor reaction uniformity of the chlorination reaction. The first is that the structure of the polypropylene after foaming is a closed pore structure, so there are a large number of closed pores in the porous powdered polypropylene prepared after granulation, crushing and screening, resulting in that the foaming has no obvious effect on increasing the specific surface area of ​​the polypropylene, and further leads to no obvious effect on improving the chlorination degree and solubility in organic solvents of the prepared chlorinated polypropylene; the third is that the chlorination reaction is an exothermic reaction, and too high a temperature will affect the performance of the dispersant and emulsifier used in the suspension method, and the porous powdered polypropylene will settle, resulting in poor reaction uniformity of the chlorination reaction and reduced chlorination degree of the prepared chlorinated polypropylene. Summary of the invention

[0007] In view of the shortcomings of the prior art, the present invention provides a method for preparing chlorinated polypropylene, which can improve the reaction uniformity in the preparation and ensure that the polypropylene does not settle in the preparation. The prepared chlorinated polypropylene has a high chlorination degree and good solubility in organic solvents, and can avoid the use of carbon tetrachloride solvent.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0009] A method for preparing chlorinated polypropylene comprises the following steps: preparing modified calcium carbonate whiskers, preparing a foaming agent, preparing porous powdered polypropylene, preparing a Pickering emulsifier, and chlorinating;

[0010] The method for preparing modified calcium carbonate whiskers comprises the following steps: preparing calcium carbonate whiskers and modifying them;

[0011] The method for preparing calcium carbonate whiskers comprises adding calcium oxide and deionized water into a reactor, controlling the temperature of the reactor to 85-90° C., controlling the stirring speed to 300-400 rpm, stirring for 80-90 min, and obtaining a calcium hydroxide suspension; adding magnesium nitrate hexahydrate and deionized water into a reactor, controlling the stirring speed of the reactor to 200-300 rpm, stirring at room temperature for 20-30 min, and obtaining a magnesium nitrate aqueous solution; adding the calcium hydroxide suspension and the magnesium nitrate aqueous solution into a reactor, controlling the stirring speed of the reactor to 50-100 rpm, stirring at room temperature for 30-40 min, controlling the temperature of the reactor to 85-90° C., introducing carbon dioxide until the pH value is 6.8-7, transferring the mixture into a filter for filtration, taking a filter residue, washing the filter residue with deionized water for 3-4 times, and transferring the mixture into an oven for drying, and obtaining calcium carbonate whiskers;

[0012] In the preparation of calcium carbonate whiskers, the mass ratio of calcium oxide, deionized water, magnesium nitrate hexahydrate, and deionized water is 57-60:8000-8200:480-500:2300-2400;

[0013] The carbon dioxide is introduced at a rate of 90-95 mL / min;

[0014] The modification comprises adding calcium carbonate whiskers, hexadecyltrimethoxysilane, 3-aminopropyltrimethoxysilane and anhydrous ethanol into a reaction kettle, controlling the temperature of the reaction kettle to 55-60° C., controlling the stirring speed to 50-100 rpm, stirring for 20-30 min, adding ammonia water, continuing stirring for 5-5.5 h, filtering in a filter, taking the filter residue, washing the filter residue with anhydrous ethanol for 4-5 times, and drying in an oven to obtain modified calcium carbonate whiskers;

[0015] In the modification, the mass ratio of calcium carbonate whiskers, hexadecyltrimethoxysilane, 3-aminopropyltrimethoxysilane, anhydrous ethanol and ammonia water is 100-105:18-19:1-1.2:7000-7500:60-65;

[0016] The mass concentration of the ammonia water is 25%;

[0017] The foaming agent is prepared by adding calcium carbonate, 3-aminopropyltrimethoxysilane, anhydrous ethanol and deionized water into a reaction kettle, controlling the temperature of the reaction kettle to 70-75° C., controlling the stirring speed to 200-300 rpm, stirring for 9-10 hours, filtering in a filter, taking the filter residue, washing the filter residue with anhydrous ethanol for 3-4 times, and drying in an oven to obtain the foaming agent;

[0018] In the preparation of the foaming agent, the mass ratio of calcium carbonate, 3-aminopropyltrimethoxysilane, anhydrous ethanol and deionized water is 100-105:45-50:5000-5200:40-50;

[0019] The average particle size of the calcium carbonate is 2 μm;

[0020] The method for preparing porous powdered polypropylene comprises adding polypropylene resin, modified calcium carbonate whisker and foaming agent into a mixer, controlling the stirring speed of the mixer to 300-400 rpm, stirring for 30-40 minutes, transferring the mixture into a twin-screw extruder, and extruding to obtain a mixture; adding the mixture into a single-screw extruder, injecting supercritical carbon dioxide into the compression section of the single-screw extruder, and extruding to obtain foamed polypropylene; adding the foamed polypropylene into a low-temperature freezing crusher for crushing, and after crushing, passing through a 100-mesh sieve to obtain porous powdered polypropylene;

[0021] In the preparation of porous powdered polypropylene, the mass ratio of polypropylene resin, modified calcium carbonate whisker and foaming agent is 100:7-8:10-12;

[0022] The mass ratio of the mixture to supercritical carbon dioxide is 100:9-10;

[0023] The injection pressure of supercritical carbon dioxide is 15-18MPa;

[0024] The temperature of the twin-screw extruder is 195-210°C;

[0025] The temperature of the single screw extruder is 195-210°C;

[0026] The melt index of the polypropylene resin at 230° C. and 2.16 kg is 20 g / 10 min;

[0027] The preparation of the Pickering emulsifier comprises the following steps: preparing hollow silica and modifying its surface;

[0028] The hollow silica is prepared by adding calcium carbonate, hexadecyltrimethylammonium bromide, anhydrous ethanol and deionized water into a reactor, controlling the stirring speed of the reactor to 200-300 rpm, stirring at room temperature for 50-60 min, adding ammonia water, continuing stirring for 50-60 min, dropping ethyl orthosilicate, continuing stirring for 14-15 h after the dropping is completed, transferring to a centrifuge, controlling the speed of the centrifuge to 7000-8000 rpm, centrifuging for 10-11 min, taking a precipitate, adding it to a reactor with a hydrochloric acid aqueous solution, controlling the stirring speed of the reactor to 200-300 rpm, stirring at room temperature for 20-30 min, transferring to a centrifuge, controlling the speed of the centrifuge to 12000-13000 rpm, centrifuging for 15-16 min, taking a precipitate, washing the precipitate with deionized water for 3-4 times, and transferring to an oven for drying to obtain hollow silica;

[0029] In the preparation of hollow silica, the mass ratio of calcium carbonate, hexadecyltrimethylammonium bromide, anhydrous ethanol, deionized water, ammonia water, ethyl orthosilicate, and hydrochloric acid aqueous solution is 100-110:10-12:150-160:60-80:60-70:370-400:1000-1100;

[0030] The mass concentration of the ammonia water is 25%;

[0031] The mass concentration of the hydrochloric acid aqueous solution is 10%;

[0032] The dropping speed of the tetraethyl orthosilicate is 3-4 g / min;

[0033] The particle size of the calcium carbonate is 100 nm;

[0034] The surface modification comprises adding hollow silica, thionyl chloride and anhydrous ethanol to a reactor with a reflux device, controlling the temperature of the reactor to 75-80°C, controlling the stirring speed to 200-300 rpm, reflux stirring for 12-13 hours, transferring to a centrifuge, controlling the speed of the centrifuge to 12000-13000 rpm, centrifuging for 18-20 minutes, taking a precipitate, washing the precipitate 3-4 times with anhydrous ethanol, transferring to an oven for drying, adding ethylenediamine and deionized water to a reactor with a reflux device, controlling the temperature of the reactor to 100-105°C, controlling the stirring speed to 200-300 rpm, reflux stirring for 39-40 hours, transferring to a centrifuge, controlling the speed of the centrifuge to 11000-12000 rpm, centrifuging for 15-16 minutes, taking a precipitate, washing the precipitate 3-4 times with deionized water, transferring to an oven for drying, and obtaining a Pickering emulsifier;

[0035] In the surface modification, the mass ratio of hollow silica, thionyl chloride, anhydrous ethanol, ethylenediamine and deionized water is 85-90:85-95:9000-9500:160-170:5500-6000;

[0036] The chlorination comprises adding porous powdered polypropylene, sodium polymethacrylate, Pickering emulsifier, dibenzoyl peroxide and hydrochloric acid aqueous solution into a reaction kettle, controlling the stirring speed to 200-300 rpm, stirring at room temperature for 40-45 minutes, adding sodium dodecylbenzene sulfonate, stirring for 20-25 minutes, heating to 90-95° C., then introducing nitrogen, and then introducing chlorine, sealing the reaction kettle, continuously introducing chlorine to control the pressure in the reaction kettle to 0.3-0.32 MPa, keeping the temperature and pressure for 60-65 minutes, keeping the pressure unchanged, heating to 115-120° C., keeping the temperature and pressure for 140-150 minutes, and naturally cooling to room temperature to obtain a chlorinated product, and post-treating the chlorinated product to obtain chlorinated polypropylene;

[0037] In the chlorination, the mass ratio of porous powdered polypropylene, sodium polymethacrylate, Pickering emulsifier, dibenzoyl peroxide, hydrochloric acid aqueous solution, and sodium dodecylbenzene sulfonate is 2000:80-85:45-50:20-21:28000-30000:30-32;

[0038] The nitrogen is introduced at a speed of 300-350 g / min and for a time of 30-35 min;

[0039] The chlorine gas is introduced at a speed of 250-280 g / min for a time of 9-10 min;

[0040] The mass concentration of the hydrochloric acid aqueous solution is 20%;

[0041] The heating rates when the temperature is raised to 90-95°C and when the temperature is raised to 115-120°C are both 2-3°C / min;

[0042] The post-treatment includes deacidification, water washing and drying.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] (1) The method for preparing chlorinated polypropylene of the present invention comprises adding modified calcium carbonate whiskers in the step of preparing porous powdered polypropylene, wherein the modified calcium carbonate whiskers are calcium carbonate whiskers modified by hexadecyltrimethoxysilane and 3-aminopropyltrimethoxysilane, and the amount of hexadecyltrimethoxysilane used is controlled to be greater than that of 3-aminopropyltrimethoxysilane, wherein hexadecyltrimethoxysilane can introduce hexadecyl groups, and 3-aminopropyltrimethoxysilane can introduce aminopropyl groups, and both hexadecyl groups and aminopropyl groups can avoid agglomeration of calcium carbonate whiskers, and the hexadecyl groups have a strong binding force with polypropylene and can also reduce the adsorption capacity of calcium carbonate whiskers for carbon dioxide, and the aminopropyl groups have a weak binding force with polypropylene and can also improve the adsorption capacity of calcium carbonate whiskers for carbon dioxide, and since calcium carbonate can act as a nucleating agent during foaming to adsorb foaming gas to form bubble nuclei, the adsorption capacity of carbon dioxide can affect the size and number of pores formed, and during the foaming process, carbon dioxide can form fine closed gas at the aminopropyl groups on the surface of the modified calcium carbonate whiskers The porous polypropylene powder is a kind of polypropylene with a plurality of porous particles, and the porous polypropylene powder is a kind of polypropylene with a plurality of porous particles. ..., and the porous polypropylene powder is a kind of polypropylene with a plurality of porous particles, and the porous polypropylene powder is a kind of polypropylene with a plurality of porous particles, and the porous polypropylene powder is a kind of polypropylene with a plurality of porous particles, and the porous polypropylene powder is a kind ofIn addition, a Pickering emulsifier is added in the chlorination step, and the Pickering emulsifier is hollow silica with amphiphilicity. In the chlorination step, porous powdered polypropylene is first mixed with the Pickering emulsifier, and the Pickering emulsifier can be coated on the surface of the powdered polypropylene to stabilize the emulsification. Then, sodium dodecylbenzene sulfonate is added, and the sodium dodecylbenzene sulfonate can be coated on the surface of the Pickering emulsifier to further stabilize the emulsification. The hollow silica can play a role in heat insulation, thereby avoiding rapid temperature rise caused by heat release of the chlorination reaction and sedimentation caused by thermal decomposition of the sodium dodecylbenzene sulfonate, and further avoiding the problem of poor reaction uniformity of the chlorination reaction caused by sedimentation and reduced chlorination degree of the prepared chlorinated polypropylene, thereby improving the reaction uniformity in the preparation, ensuring that the polypropylene does not settle in the preparation, and the prepared chlorinated polypropylene has a high chlorination degree and good solubility in organic solvents.

[0045] (2) The method for preparing chlorinated polypropylene of the present invention can improve the reaction uniformity in the preparation process. The prepared chlorinated polypropylene has good solubility in organic solvents. 5 g of the prepared chlorinated polypropylene is dissolved in 200 g of xylene and 200 g of carbon tetrachloride respectively, and stirred at 80° C. at a stirring speed of 100 rpm for 1 min. The chlorinated polypropylene can be completely dissolved, and then naturally cooled to room temperature without precipitation.

[0046] (3) The method for preparing chlorinated polypropylene of the present invention can ensure that polypropylene does not settle during the preparation process;

[0047] (4) The method for preparing chlorinated polypropylene of the present invention has a high degree of chlorination of the prepared chlorinated polypropylene, and the chlorine content of the prepared chlorinated polypropylene can reach 62.4-64.8%;

[0048] (5) The method for preparing chlorinated polypropylene of the present invention can avoid the use of carbon tetrachloride solvent. DETAILED DESCRIPTION

[0049] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific implementation methods of the present invention are now described.

[0050] Example 1

[0051] A method for preparing chlorinated polypropylene, specifically:

[0052] 1. Preparation of modified calcium carbonate whiskers:

[0053] (1) Preparation of calcium carbonate whiskers: 57 g of calcium oxide and 8000 g of deionized water are added to a reactor, the temperature of the reactor is controlled to 85° C., the stirring speed is controlled to 300 rpm, and the mixture is stirred for 80 min to obtain a calcium hydroxide suspension; 480 g of magnesium nitrate hexahydrate and 2300 g of deionized water are added to a reactor, the stirring speed of the reactor is controlled to 200 rpm, and the mixture is stirred at room temperature for 20 min to obtain a magnesium nitrate aqueous solution; all of the above calcium hydroxide suspension and all of the above magnesium nitrate aqueous solution are added to a reactor, the stirring speed of the reactor is controlled to 50 rpm, and the mixture is stirred at room temperature for 30 min, the temperature of the reactor is controlled to 85° C., carbon dioxide is introduced at a rate of 90 mL / min until the pH value is 6.8, the mixture is filtered in a filter, the filter residue is taken, the filter residue is washed 3 times with deionized water, and the mixture is dried in an oven to obtain calcium carbonate whiskers;

[0054] (2) Modification: 100 g of calcium carbonate whiskers, 18 g of hexadecyltrimethoxysilane, 1 g of 3-aminopropyltrimethoxysilane, and 7000 g of anhydrous ethanol were added to a reactor, the temperature of the reactor was controlled to 55°C, the stirring speed was controlled to 50 rpm, and the mixture was stirred for 20 min. 60 g of 25% ammonia water was added, and the mixture was stirred for 5 h. The mixture was filtered through a filter, the residue was washed with anhydrous ethanol for 4 times, and the residue was dried in an oven to obtain modified calcium carbonate whiskers.

[0055] 2. Preparation of a foaming agent: 100 g of calcium carbonate, 45 g of 3-aminopropyltrimethoxysilane, 5000 g of anhydrous ethanol, and 40 g of deionized water were added to a reactor, the temperature of the reactor was controlled to 70° C., the stirring speed was controlled to 200 rpm, and the mixture was stirred for 9 h. The mixture was filtered through a filter, the residue was washed three times with anhydrous ethanol, and the residue was dried in an oven to obtain a foaming agent.

[0056] The average particle size of the calcium carbonate is 2 μm;

[0057] 3. Preparation of porous powdered polypropylene: adding polypropylene resin, modified calcium carbonate whisker, and foaming agent to a mixer in a mass ratio of 100:7:10, controlling the stirring speed of the mixer to 300 rpm, stirring for 30 minutes, transferring to a twin-screw extruder, controlling the temperature of the twin-screw extruder to 195° C., and extruding to obtain a mixture; adding the mixture to a single-screw extruder, controlling the temperature of the single-screw extruder to 195° C., injecting supercritical carbon dioxide into the compression section of the single-screw extruder, controlling the mass ratio of the mixture to the supercritical carbon dioxide to 100:9, and the injection pressure of the supercritical carbon dioxide to 15 MPa, and extruding to obtain foamed polypropylene; adding the foamed polypropylene to a low-temperature freezing crusher for crushing, and after crushing, passing through a 100-mesh sieve to obtain porous powdered polypropylene;

[0058] The melt index of the polypropylene resin at 230° C. and 2.16 kg is 20 g / 10 min;

[0059] 4. Preparation of Pickering emulsifier:

[0060] (1) Preparation of hollow silica: 100 g of calcium carbonate, 10 g of hexadecyltrimethylammonium bromide, 150 g of anhydrous ethanol and 60 g of deionized water were added to a reactor, the stirring speed of the reactor was controlled to 200 rpm, and the mixture was stirred at room temperature for 50 min. 60 g of ammonia water with a mass concentration of 25% was added, and the stirring was continued for 50 min. 370 g of ethyl orthosilicate was added dropwise, and the dropping speed was controlled to 3 g / min. After the dropping was completed, the mixture was stirred for 14 h. The mixture was transferred to a centrifuge, the speed of the centrifuge was controlled to 7000 rpm, and the mixture was centrifuged for 10 min. The precipitate was taken and added to the reactor with 1000 g of a hydrochloric acid aqueous solution with a mass concentration of 10%. The stirring speed of the reactor was controlled to 200 rpm, and the mixture was stirred at room temperature for 20 min. The mixture was transferred to a centrifuge, the speed of the centrifuge was controlled to 12000 rpm, and the mixture was centrifuged for 15 min. The precipitate was taken and washed with deionized water for 3 times. The precipitate was transferred to an oven for drying to obtain hollow silica.

[0061] The particle size of the calcium carbonate is 100 nm;

[0062] (2) Surface modification: 85 g of hollow silica, 85 g of thionyl chloride, and 9000 g of anhydrous ethanol were added to a reactor with a reflux device, the temperature of the reactor was controlled to 75 ° C, the stirring speed was controlled to 200 rpm, and refluxed and stirred for 12 h, then transferred to a centrifuge, the speed of the centrifuge was controlled to 12000 rpm, centrifuged for 18 min, the precipitate was taken, the precipitate was washed 3 times with anhydrous ethanol, and then transferred to an oven for drying, and 160 g of ethylenediamine and 5500 g of deionized water were added to a reactor with a reflux device, the temperature of the reactor was controlled to 100 ° C, the stirring speed was controlled to 200 rpm, refluxed and stirred for 39 h, then transferred to a centrifuge, the speed of the centrifuge was controlled to 11000 rpm, centrifuged for 15 min, the precipitate was taken, the precipitate was washed 3 times with deionized water, and then transferred to an oven for drying to obtain a Pickering emulsifier;

[0063] 5. Chlorination: 2000g of porous powdered polypropylene, 80g of sodium polymethacrylate, 45g of Pickering emulsifier, 20g of dibenzoyl peroxide, and 28000g of 20% hydrochloric acid aqueous solution were added to a reactor, the stirring speed was controlled to 200rpm, and the mixture was stirred at room temperature for 40min. 30g of sodium dodecylbenzene sulfonate was added, and the mixture was stirred for 20min. The mixture was heated to 90°C at a heating rate of 2°C / min, and nitrogen was then introduced at a rate of 300g / min for 30min, and chlorine was then introduced at a rate of 250g / min for 9min. The reactor was sealed, and chlorine was continuously introduced to control the pressure in the reactor to 0.3MPa. The reaction mixture was kept warm and pressure maintained for 60min, and the pressure was kept constant. The mixture was heated to 115°C at a heating rate of 2°C / min for 140min, and the mixture was naturally cooled to room temperature to obtain a chlorinated product. The chlorinated product was deacidified, washed with water, and dried to obtain chlorinated polypropylene.

[0064] Example 2

[0065] A method for preparing chlorinated polypropylene, specifically:

[0066] 1. Preparation of modified calcium carbonate whiskers:

[0067] (1) Preparation of calcium carbonate whiskers: 58 g of calcium oxide and 8100 g of deionized water are added to a reactor, the temperature of the reactor is controlled to 85° C., the stirring speed is controlled to 350 rpm, and the mixture is stirred for 85 min to obtain a calcium hydroxide suspension; 500 g of magnesium nitrate hexahydrate and 2350 g of deionized water are added to a reactor, the stirring speed of the reactor is controlled to 250 rpm, and the mixture is stirred at room temperature for 25 min to obtain a magnesium nitrate aqueous solution; all of the above calcium hydroxide suspension and all of the above magnesium nitrate aqueous solution are added to a reactor, the stirring speed of the reactor is controlled to 80 rpm, and the mixture is stirred at room temperature for 35 min, the temperature of the reactor is controlled to 88° C., carbon dioxide is introduced at a rate of 92 mL / min until the pH value is 6.9, the mixture is filtered in a filter, the filter residue is taken, the filter residue is washed 3 times with deionized water, and the mixture is dried in an oven to obtain calcium carbonate whiskers;

[0068] (2) Modification: 102 g of calcium carbonate whiskers, 18.5 g of hexadecyltrimethoxysilane, 1.1 g of 3-aminopropyltrimethoxysilane, and 7200 g of anhydrous ethanol were added to a reactor, the temperature of the reactor was controlled to 58 ° C, the stirring speed was controlled to 80 rpm, and the mixture was stirred for 25 min. 62 g of 25% ammonia water was added, and the mixture was stirred for 5.5 h. The mixture was filtered through a filter, the residue was washed with anhydrous ethanol for 4 times, and the residue was dried in an oven to obtain modified calcium carbonate whiskers.

[0069] 2. Preparation of a foaming agent: 102 g of calcium carbonate, 48 g of 3-aminopropyltrimethoxysilane, 5100 g of anhydrous ethanol, and 45 g of deionized water were added to a reactor, the temperature of the reactor was controlled to 72 ° C, the stirring speed was controlled to 250 rpm, and the mixture was stirred for 9.5 h. The mixture was filtered through a filter, the residue was washed three times with anhydrous ethanol, and the residue was dried in an oven to obtain a foaming agent;

[0070] The average particle size of the calcium carbonate is 2 μm;

[0071] 3. Preparation of porous powdered polypropylene: adding polypropylene resin, modified calcium carbonate whisker, and foaming agent to a mixer in a mass ratio of 100:7.5:11, controlling the stirring speed of the mixer to 350 rpm, stirring for 35 minutes, transferring to a twin-screw extruder, controlling the temperature of the twin-screw extruder to 205° C., and extruding to obtain a mixture; adding the mixture to a single-screw extruder, controlling the temperature of the single-screw extruder to 205° C., injecting supercritical carbon dioxide into the compression section of the single-screw extruder, controlling the mass ratio of the mixture to the supercritical carbon dioxide to 100:9.5, and the injection pressure of the supercritical carbon dioxide to 16 MPa, and extruding to obtain foamed polypropylene; adding the foamed polypropylene to a low-temperature freezing crusher for crushing, and after crushing, passing through a 100-mesh sieve to obtain porous powdered polypropylene;

[0072] The melt index of the polypropylene resin at 230° C. and 2.16 kg is 20 g / 10 min;

[0073] 4. Preparation of Pickering emulsifier:

[0074] (1) Preparation of hollow silica: 105 g of calcium carbonate, 11 g of hexadecyltrimethylammonium bromide, 155 g of anhydrous ethanol and 70 g of deionized water were added to a reactor, the stirring speed of the reactor was controlled to 250 rpm, and the mixture was stirred at room temperature for 55 min. 65 g of ammonia water with a mass concentration of 25% was added, and the stirring was continued for 55 min. 380 g of ethyl orthosilicate was added dropwise, and the dropping speed was controlled to 3 g / min. After the dropping was completed, the mixture was stirred for 14.5 h. The mixture was transferred to a centrifuge, the speed of the centrifuge was controlled to 7500 rpm, and the mixture was centrifuged for 10.5 min. The precipitate was taken and added to the reactor with 1050 g of a hydrochloric acid aqueous solution with a mass concentration of 10%. The stirring speed of the reactor was controlled to 250 rpm, and the mixture was stirred at room temperature for 25 min. The mixture was transferred to a centrifuge, the speed of the centrifuge was controlled to 13000 rpm, and the mixture was centrifuged for 15 min. The precipitate was taken and washed with deionized water for 3 times. The precipitate was transferred to an oven for drying to obtain hollow silica.

[0075] The particle size of the calcium carbonate is 100 nm;

[0076] (2) Surface modification: 88 g of hollow silica, 90 g of thionyl chloride, and 9200 g of anhydrous ethanol were added to a reactor with a reflux device, the temperature of the reactor was controlled to 78 ° C, the stirring speed was controlled to 250 rpm, and refluxed and stirred for 12.5 h, transferred to a centrifuge, the speed of the centrifuge was controlled to 13000 rpm, centrifuged for 18 min, the precipitate was taken, the precipitate was washed 3 times with anhydrous ethanol, and transferred to an oven for drying, and 165 g of ethylenediamine and 5800 g of deionized water were added to a reactor with a reflux device, the temperature of the reactor was controlled to 105 ° C, the stirring speed was controlled to 250 rpm, refluxed and stirred for 39.5 h, transferred to a centrifuge, the speed of the centrifuge was controlled to 12000 rpm, centrifuged for 15 min, the precipitate was taken, the precipitate was washed 3 times with deionized water, and transferred to an oven for drying to obtain a Pickering emulsifier;

[0077] 5. Chlorination: 2000g porous powdered polypropylene, 82g sodium polymethacrylate, 48g Pickering emulsifier, 20.5g dibenzoyl peroxide, 29000g hydrochloric acid aqueous solution with a mass concentration of 20% were added to the reactor, the stirring speed was controlled to 250rpm, and the mixture was stirred at room temperature for 42min. 31g sodium dodecylbenzene sulfonate was added, and the mixture was stirred for 22min. The temperature was raised to 92°C at a heating rate of 2°C / min, and nitrogen was then introduced at a rate of 320g / min for 32min. Chlorine was then introduced at a rate of 260g / min for 10min. The reactor was sealed, and chlorine was continuously introduced to control the pressure in the reactor to 0.31MPa. The reaction mixture was kept warm and pressure maintained for 62min. The pressure was kept constant, and the temperature was raised to 118°C at a heating rate of 2°C / min for 145min. The reaction mixture was naturally cooled to room temperature to obtain a chlorinated product. The chlorinated product was deacidified, washed with water, and dried to obtain chlorinated polypropylene.

[0078] Example 3

[0079] A method for preparing chlorinated polypropylene, specifically:

[0080] 1. Preparation of modified calcium carbonate whiskers:

[0081] (1) Preparation of calcium carbonate whiskers: 60 g of calcium oxide and 8200 g of deionized water are added to a reactor, the temperature of the reactor is controlled to 90° C., the stirring speed is controlled to 400 rpm, and the mixture is stirred for 90 min to obtain a calcium hydroxide suspension; 520 g of magnesium nitrate hexahydrate and 2400 g of deionized water are added to a reactor, the stirring speed of the reactor is controlled to 300 rpm, and the mixture is stirred at room temperature for 30 min to obtain a magnesium nitrate aqueous solution; all of the above calcium hydroxide suspension and all of the above magnesium nitrate aqueous solution are added to a reactor, the stirring speed of the reactor is controlled to 100 rpm, and the mixture is stirred at room temperature for 40 min, the temperature of the reactor is controlled to 90° C., carbon dioxide is introduced at a rate of 95 mL / min until the pH value is 7, the mixture is filtered in a filter, the filter residue is taken, the filter residue is washed 4 times with deionized water, and the mixture is dried in an oven to obtain calcium carbonate whiskers;

[0082] (2) Modification: 105 g of calcium carbonate whiskers, 19 g of hexadecyltrimethoxysilane, 1.2 g of 3-aminopropyltrimethoxysilane, and 7500 g of anhydrous ethanol were added to a reactor, the temperature of the reactor was controlled to 60°C, the stirring speed was controlled to 100 rpm, and the stirring was performed for 30 min. 65 g of 25% ammonia water was added, and the stirring was continued for 5.5 h. The mixture was filtered through a filter, the residue was washed with anhydrous ethanol for 5 times, and the residue was dried in an oven to obtain modified calcium carbonate whiskers.

[0083] 2. Preparation of a foaming agent: Add 105 g of calcium carbonate, 50 g of 3-aminopropyltrimethoxysilane, 5200 g of anhydrous ethanol, and 50 g of deionized water to a reactor, control the temperature of the reactor to 75 ° C, control the stirring speed to 300 rpm, stir for 10 hours, transfer to a filter for filtration, take the filter residue, wash the filter residue 4 times with anhydrous ethanol, transfer to an oven for drying, and obtain a foaming agent;

[0084] The average particle size of the calcium carbonate is 2 μm;

[0085] 3. Preparation of porous powdered polypropylene: adding polypropylene resin, modified calcium carbonate whisker, and foaming agent to a mixer in a mass ratio of 100:8:12, controlling the stirring speed of the mixer to 400 rpm, stirring for 40 minutes, transferring to a twin-screw extruder, controlling the temperature of the twin-screw extruder to 210° C., and extruding to obtain a mixture; adding the mixture to a single-screw extruder, controlling the temperature of the single-screw extruder to 210° C., injecting supercritical carbon dioxide into the compression section of the single-screw extruder, controlling the mass ratio of the mixture to the supercritical carbon dioxide to 100:10, and the injection pressure of the supercritical carbon dioxide to 18 MPa, and extruding to obtain foamed polypropylene; adding the foamed polypropylene to a low-temperature freezing crusher for crushing, and after crushing, passing through a 100-mesh sieve to obtain porous powdered polypropylene;

[0086] The melt index of the polypropylene resin at 230° C. and 2.16 kg is 20 g / 10 min;

[0087] 4. Preparation of Pickering emulsifier:

[0088] (1) Preparation of hollow silica: 110 g of calcium carbonate, 12 g of hexadecyltrimethylammonium bromide, 160 g of anhydrous ethanol and 80 g of deionized water were added to a reactor, the stirring speed of the reactor was controlled to 300 rpm, and the mixture was stirred at room temperature for 60 min. 70 g of ammonia water with a mass concentration of 25% was added, and the stirring was continued for 60 min. 400 g of ethyl orthosilicate was added dropwise, and the dropping speed was controlled to 4 g / min. After the dropping was completed, the mixture was stirred for 15 h. The mixture was transferred to a centrifuge, the speed of the centrifuge was controlled to 8000 rpm, and the mixture was centrifuged for 11 min. The precipitate was taken and added to the reactor with 1100 g of a hydrochloric acid aqueous solution with a mass concentration of 10%. The stirring speed of the reactor was controlled to 300 rpm, and the mixture was stirred at room temperature for 30 min. The mixture was transferred to a centrifuge, the speed of the centrifuge was controlled to 13000 rpm, and the mixture was centrifuged for 16 min. The precipitate was taken and washed with deionized water for 4 times. The precipitate was transferred to an oven for drying to obtain hollow silica.

[0089] The particle size of the calcium carbonate is 100 nm;

[0090] (2) Surface modification: 90 g hollow silica, 95 g thionyl chloride, and 9500 g anhydrous ethanol were added to a reactor with a reflux device, the temperature of the reactor was controlled to 80 ° C, the stirring speed was controlled to 300 rpm, and the mixture was refluxed and stirred for 13 h. The mixture was transferred to a centrifuge, the speed of the centrifuge was controlled to 13000 rpm, and the mixture was centrifuged for 20 min. The precipitate was taken, and the precipitate was washed 4 times with anhydrous ethanol, and the mixture was transferred to an oven for drying. The mixture was added with 170 g ethylenediamine and 6000 g deionized water to a reactor with a reflux device, the temperature of the reactor was controlled to 105 ° C, the stirring speed was controlled to 300 rpm, and the mixture was refluxed and stirred for 40 h. The mixture was transferred to a centrifuge, the speed of the centrifuge was controlled to 12000 rpm, and the mixture was centrifuged for 16 min. The precipitate was taken, and the precipitate was washed 4 times with deionized water, and the mixture was transferred to an oven for drying to obtain a Pickering emulsifier.

[0091] 5. Chlorination: 2000g porous powdered polypropylene, 85g sodium polymethacrylate, 50g Pickering emulsifier, 21g dibenzoyl peroxide, 30000g hydrochloric acid aqueous solution with a mass concentration of 20% were added to the reactor, the stirring speed was controlled to 300rpm, and the mixture was stirred at room temperature for 45min. 32g sodium dodecylbenzene sulfonate was added, and the mixture was stirred for 25min. The temperature was raised to 95°C at a heating rate of 3°C / min, and then nitrogen was introduced at a rate of 350g / min for 35min, and then chlorine was introduced at a rate of 280g / min for 10min. The reactor was sealed, and chlorine was continuously introduced to control the pressure in the reactor to 0.32MPa. The reaction mixture was kept warm and pressure maintained for 65min, and the pressure was kept constant. The reaction mixture was heated to 120°C at a heating rate of 3°C / min, and the temperature was maintained for 150min. The reaction mixture was naturally cooled to room temperature to obtain a chlorinated product. The chlorinated product was deacidified, washed with water, and dried to obtain chlorinated polypropylene.

[0092] Comparative Example 1

[0093] Based on the preparation method of Example 2, the step of preparing modified calcium carbonate whiskers in step 1 is omitted, and the addition of modified calcium carbonate whiskers in the step of preparing porous powdered polypropylene in step 3 is omitted;

[0094] The remaining operations are the same as those in Example 1.

[0095] Comparative Example 2

[0096] On the basis of the preparation method of Example 2, the step of preparing the Pickering emulsifier in step 4 is omitted, and the addition of the Pickering emulsifier is omitted in the chlorination step in step 5, and the addition time of sodium dodecylbenzene sulfonate is adjusted. Specifically, the chlorination step in step 5 is changed to:

[0097] 2000g of porous powdered polypropylene, 82g of sodium polymethacrylate, 31g of sodium dodecylbenzene sulfonate, 20.5g of dibenzoyl peroxide, and 29000g of a 20% hydrochloric acid aqueous solution were added to a reactor, the stirring speed was controlled to 250rpm, stirred at room temperature for 42min, heated to 92°C at a heating rate of 2°C / min, then nitrogen was introduced at a feeding rate of 320g / min for 32min, and then chlorine was introduced at a feeding rate of 260g / min for 10min, the reactor was sealed, chlorine was continuously introduced to control the pressure in the reactor to 0.31MPa, the temperature was kept at 62min, the pressure was kept constant, the temperature was raised to 118°C at a heating rate of 2°C / min, the temperature was kept at 145min, and the reaction was naturally cooled to room temperature to obtain a chlorinated product, and the chlorinated product was deacidified, washed with water, and dried to obtain chlorinated polypropylene;

[0098] The remaining operations are the same as those in Example 1.

[0099] Test Example 1

[0100] Chlorinated polypropylene was prepared according to the preparation methods of Examples 1-3 and Comparative Examples 1-2, and whether there was a sedimentation problem during chlorination in the fifth chlorination step was observed. The observation results were as follows:

[0101]

[0102] Test Example 2

[0103] Chlorinated polypropylene was prepared according to the preparation methods of Examples 1-3 and Comparative Examples 1-2, and then the chlorine content of the prepared chlorinated polypropylene was tested. The test results are as follows:

[0104]

[0105] Test Example 3

[0106] Chlorinated polypropylene was prepared according to the preparation methods of Examples 1-3 and Comparative Examples 1-2, and 5 g of each was dissolved in 200 g of xylene, stirred at 80° C. at a stirring speed of 100 rpm for 1 min, and observed whether it was dissolved. Then, it was naturally cooled to room temperature and observed whether precipitation occurred. The observation results are as follows:

[0107]

[0108] Test Example 4

[0109] Chlorinated polypropylene was prepared according to the preparation methods of Examples 1-3 and Comparative Examples 1-2, and 5 g of each was dissolved in 200 g of carbon tetrachloride, stirred at 80° C. at a stirring speed of 100 rpm for 1 min, and observed whether it was dissolved. Then, it was naturally cooled to room temperature and observed whether precipitation occurred. The observation results are as follows:

[0110]

[0111] It can be seen from the above results that by adding modified calcium carbonate whiskers in the step of preparing porous powdered polypropylene, the chlorine content and solubility of the prepared chlorinated polypropylene in organic solvents can be increased;

[0112] By adding a Pickering emulsifier in the chlorination step, the sedimentation problem in the chlorination step can be avoided, and the chlorine content and solubility in organic solvents of the prepared chlorinated polypropylene can be increased.

[0113] Unless otherwise specified, all percentages used in the present invention are by mass.

[0114] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing chlorinated polypropylene, It is characterized in that The method comprises the following steps: preparing modified calcium carbonate whiskers, preparing a foaming agent, preparing porous powdered polypropylene, preparing a Pickering emulsifier, and chlorinating; The method for preparing modified calcium carbonate whiskers comprises the following steps: preparing calcium carbonate whiskers and modifying them; The method for preparing calcium carbonate whiskers comprises mixing calcium oxide and deionized water, stirring at 85-90° C. to obtain a calcium hydroxide suspension; mixing magnesium nitrate hexahydrate and deionized water, stirring at room temperature to obtain a magnesium nitrate aqueous solution; mixing the calcium hydroxide suspension and the magnesium nitrate aqueous solution, stirring at room temperature, heating to 85-90° C., introducing carbon dioxide until the pH value is 6.8-7, filtering, washing and drying the filter residue to obtain calcium carbonate whiskers; The modification comprises mixing calcium carbonate whiskers, hexadecyl trimethoxysilane, 3-aminopropyl trimethoxysilane and anhydrous ethanol, stirring at 55-60° C., adding ammonia water, continuing stirring, filtering, washing and drying the filter residue to obtain modified calcium carbonate whiskers; The method for preparing porous powdered polypropylene comprises mixing polypropylene resin, modified calcium carbonate whisker and foaming agent, transferring the mixture into a twin-screw extruder, controlling the temperature of the twin-screw extruder to 195-210° C., and extruding the mixture; adding the mixture into a single-screw extruder, injecting supercritical carbon dioxide into the compression section of the single-screw extruder, and extruding to obtain foamed polypropylene; crushing the foamed polypropylene, sieving, and obtaining porous powdered polypropylene; The preparation of the Pickering emulsifier comprises the following steps: preparing hollow silica and modifying its surface; The hollow silica is prepared by mixing calcium carbonate, hexadecyltrimethylammonium bromide, anhydrous ethanol and deionized water, stirring at room temperature, adding ammonia water, continuing stirring, dropping ethyl orthosilicate, continuing stirring after the dropping, centrifuging, taking a precipitate, mixing with a hydrochloric acid aqueous solution, stirring at room temperature, centrifuging, taking a precipitate, washing and drying the precipitate to obtain the hollow silica; The surface modification comprises mixing hollow silica, thionyl chloride and anhydrous ethanol, stirring and refluxing at 75-80° C., centrifuging, taking a precipitate, washing and drying the precipitate, mixing with ethylenediamine and deionized water, stirring and refluxing at 100-105° C., centrifuging, taking a precipitate, washing and drying the precipitate to obtain a Pickering emulsifier; The chlorination comprises mixing porous powdered polypropylene, sodium polymethacrylate, Pickering emulsifier, dibenzoyl peroxide and hydrochloric acid aqueous solution, stirring at room temperature, adding sodium dodecylbenzene sulfonate, stirring, heating to 90-95° C., then introducing nitrogen, and then introducing chlorine, in a closed environment, continuously introducing chlorine to control the pressure in the reactor to 0.3-0.32 MPa, maintaining the temperature and pressure, keeping the pressure constant, heating to 115-120° C., maintaining the temperature and pressure, cooling to obtain a chlorinated product, and post-treating the chlorinated product to obtain chlorinated polypropylene.

2. The method for preparing chlorinated polypropylene according to claim 1, It is characterized in that In the preparation of calcium carbonate whiskers, the mass ratio of calcium oxide, deionized water, magnesium nitrate hexahydrate, and deionized water is 57-60:8000-8200:480-500:2300-2400; The carbon dioxide is introduced at a rate of 90-95 mL / min.

3. The method for preparing chlorinated polypropylene according to claim 1, It is characterized in that In the modification, the mass ratio of calcium carbonate whiskers, hexadecyltrimethoxysilane, 3-aminopropyltrimethoxysilane, anhydrous ethanol and ammonia water is 100-105:18-19:1-1.2:7000-7500:60-65; The mass concentration of the ammonia water is 25%.

4. The method for preparing chlorinated polypropylene according to claim 1, It is characterized in that The foaming agent is prepared by mixing calcium carbonate, 3-aminopropyltrimethoxysilane, anhydrous ethanol and deionized water, stirring at 70-75° C., filtering, washing and drying the filter residue to obtain the foaming agent.

5. The method for preparing chlorinated polypropylene according to claim 1, It is characterized in that In the preparation of the foaming agent, the mass ratio of calcium carbonate, 3-aminopropyltrimethoxysilane, anhydrous ethanol and deionized water is 100-105:45-50:5000-5200:40-50.

6. The method for preparing chlorinated polypropylene according to claim 1, It is characterized in that In the preparation of porous powdered polypropylene, the mass ratio of polypropylene resin, modified calcium carbonate whisker and foaming agent is 100:7-8:10-12; The mass ratio of the mixture to supercritical carbon dioxide is 100:9-10; The injection pressure of supercritical carbon dioxide is 15-18MPa; The temperature of the twin-screw extruder is 195-210°C; The temperature of the single screw extruder is 195-210°C.

7. The method for preparing chlorinated polypropylene according to claim 1, It is characterized in that In the preparation of hollow silica, the mass ratio of calcium carbonate, hexadecyltrimethylammonium bromide, anhydrous ethanol, deionized water, ammonia water, ethyl orthosilicate, and hydrochloric acid aqueous solution is 100-110:10-12:150-160:60-80:60-70:370-400:1000-1100; The mass concentration of the ammonia water is 25%; The mass concentration of the hydrochloric acid aqueous solution is 10%; The dropping speed of the tetraethyl orthosilicate is 3-4 g / min.

8. The method for preparing chlorinated polypropylene according to claim 1, It is characterized in that In the surface modification, the mass ratio of hollow silica, thionyl chloride, anhydrous ethanol, ethylenediamine and deionized water is 85-90:85-95:9000-9500:160-170:5500-6000.

9. The method for preparing chlorinated polypropylene according to claim 1, It is characterized in that In the chlorination, the mass ratio of porous powdered polypropylene, sodium polymethacrylate, Pickering emulsifier, dibenzoyl peroxide, hydrochloric acid aqueous solution and sodium dodecylbenzene sulfonate is 2000:80-85:45-50:20-21:28000-30000:30-32.

10. The method for preparing chlorinated polypropylene according to claim 1, It is characterized in that During the chlorination, the nitrogen is introduced at a rate of 300-350 g / min for a time of 30-35 min; The chlorine gas is introduced at a speed of 250-280 g / min and for a time of 9-10 min; The mass concentration of the hydrochloric acid aqueous solution is 20%; The heating rates when the temperature is raised to 90-95°C and when the temperature is raised to 115-120°C are both 2-3°C / min; The post-treatment includes deacidification, water washing and drying.

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