CN117209774B - Polysiloxane coated polytetrafluoroethylene anti-dripping agent and preparation method thereof - Google Patents
Polysiloxane coated polytetrafluoroethylene anti-dripping agent and preparation method thereof Download PDFInfo
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- CN117209774B CN117209774B CN202311298137.5A CN202311298137A CN117209774B CN 117209774 B CN117209774 B CN 117209774B CN 202311298137 A CN202311298137 A CN 202311298137A CN 117209774 B CN117209774 B CN 117209774B
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- -1 Polysiloxane Polymers 0.000 title claims abstract description 120
- 229920001343 polytetrafluoroethylene Polymers 0.000 title claims abstract description 84
- 239000004810 polytetrafluoroethylene Substances 0.000 title claims abstract description 84
- 239000003795 chemical substances by application Substances 0.000 title claims abstract description 59
- 229920001296 polysiloxane Polymers 0.000 title claims abstract description 49
- 238000002360 preparation method Methods 0.000 title claims abstract description 14
- 239000000839 emulsion Substances 0.000 claims abstract description 34
- 239000000178 monomer Substances 0.000 claims abstract description 18
- 238000001035 drying Methods 0.000 claims abstract description 15
- 239000003054 catalyst Substances 0.000 claims abstract description 14
- 238000006243 chemical reaction Methods 0.000 claims abstract description 12
- KPUWHANPEXNPJT-UHFFFAOYSA-N disiloxane Chemical class [SiH3]O[SiH3] KPUWHANPEXNPJT-UHFFFAOYSA-N 0.000 claims abstract description 12
- 239000002244 precipitate Substances 0.000 claims abstract description 8
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 27
- 238000000034 method Methods 0.000 claims description 20
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 claims description 9
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 9
- HTDJPCNNEPUOOQ-UHFFFAOYSA-N hexamethylcyclotrisiloxane Chemical compound C[Si]1(C)O[Si](C)(C)O[Si](C)(C)O1 HTDJPCNNEPUOOQ-UHFFFAOYSA-N 0.000 claims description 8
- JOXIMZWYDAKGHI-UHFFFAOYSA-N toluene-4-sulfonic acid Chemical compound CC1=CC=C(S(O)(=O)=O)C=C1 JOXIMZWYDAKGHI-UHFFFAOYSA-N 0.000 claims description 6
- JJRDHFIVAPVZJN-UHFFFAOYSA-N cyclotrisiloxane Chemical compound O1[SiH2]O[SiH2]O[SiH2]1 JJRDHFIVAPVZJN-UHFFFAOYSA-N 0.000 claims description 5
- 238000001291 vacuum drying Methods 0.000 claims description 5
- 239000003377 acid catalyst Substances 0.000 claims description 4
- 238000000227 grinding Methods 0.000 claims description 4
- 238000010438 heat treatment Methods 0.000 claims description 4
- WBIQQQGBSDOWNP-UHFFFAOYSA-N 2-dodecylbenzenesulfonic acid Chemical compound CCCCCCCCCCCCC1=CC=CC=C1S(O)(=O)=O WBIQQQGBSDOWNP-UHFFFAOYSA-N 0.000 claims description 3
- XMSXQFUHVRWGNA-UHFFFAOYSA-N Decamethylcyclopentasiloxane Chemical compound C[Si]1(C)O[Si](C)(C)O[Si](C)(C)O[Si](C)(C)O[Si](C)(C)O1 XMSXQFUHVRWGNA-UHFFFAOYSA-N 0.000 claims description 3
- 239000003513 alkali Substances 0.000 claims description 3
- 229940060296 dodecylbenzenesulfonic acid Drugs 0.000 claims description 3
- 238000010902 jet-milling Methods 0.000 claims description 3
- HMMGMWAXVFQUOA-UHFFFAOYSA-N octamethylcyclotetrasiloxane Chemical compound C[Si]1(C)O[Si](C)(C)O[Si](C)(C)O[Si](C)(C)O1 HMMGMWAXVFQUOA-UHFFFAOYSA-N 0.000 claims description 3
- 239000007787 solid Substances 0.000 claims description 3
- 125000003698 tetramethyl group Chemical group [H]C([H])([H])* 0.000 claims description 3
- 238000000498 ball milling Methods 0.000 claims description 2
- 238000004108 freeze drying Methods 0.000 claims description 2
- 238000009775 high-speed stirring Methods 0.000 claims description 2
- 238000007603 infrared drying Methods 0.000 claims description 2
- 238000005185 salting out Methods 0.000 claims description 2
- 238000001694 spray drying Methods 0.000 claims description 2
- 238000007605 air drying Methods 0.000 claims 1
- 238000005119 centrifugation Methods 0.000 claims 1
- 239000000203 mixture Substances 0.000 claims 1
- 239000011248 coating agent Substances 0.000 abstract description 15
- 238000000576 coating method Methods 0.000 abstract description 15
- 239000002904 solvent Substances 0.000 abstract description 3
- 239000006227 byproduct Substances 0.000 abstract description 2
- 239000011159 matrix material Substances 0.000 abstract description 2
- 239000004417 polycarbonate Substances 0.000 description 35
- 239000000463 material Substances 0.000 description 11
- 238000003756 stirring Methods 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 9
- 239000000047 product Substances 0.000 description 8
- 239000000243 solution Substances 0.000 description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- 239000004793 Polystyrene Substances 0.000 description 5
- 239000003960 organic solvent Substances 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- 229920003023 plastic Polymers 0.000 description 5
- 239000004033 plastic Substances 0.000 description 5
- 239000000843 powder Substances 0.000 description 5
- 238000002156 mixing Methods 0.000 description 4
- 239000011347 resin Substances 0.000 description 4
- 229920005989 resin Polymers 0.000 description 4
- 239000003995 emulsifying agent Substances 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 229920003229 poly(methyl methacrylate) Polymers 0.000 description 3
- 229920000515 polycarbonate Polymers 0.000 description 3
- 239000004926 polymethyl methacrylate Substances 0.000 description 3
- 229920000638 styrene acrylonitrile Polymers 0.000 description 3
- 239000011145 styrene acrylonitrile resin Substances 0.000 description 3
- RNFJDJUURJAICM-UHFFFAOYSA-N 2,2,4,4,6,6-hexaphenoxy-1,3,5-triaza-2$l^{5},4$l^{5},6$l^{5}-triphosphacyclohexa-1,3,5-triene Chemical compound N=1P(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP=1(OC=1C=CC=CC=1)OC1=CC=CC=C1 RNFJDJUURJAICM-UHFFFAOYSA-N 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- XECAHXYUAAWDEL-UHFFFAOYSA-N acrylonitrile butadiene styrene Chemical compound C=CC=C.C=CC#N.C=CC1=CC=CC=C1 XECAHXYUAAWDEL-UHFFFAOYSA-N 0.000 description 2
- 229920000122 acrylonitrile butadiene styrene Polymers 0.000 description 2
- 239000004676 acrylonitrile butadiene styrene Substances 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 239000002585 base Substances 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 239000003063 flame retardant Substances 0.000 description 2
- 230000007062 hydrolysis Effects 0.000 description 2
- 238000006460 hydrolysis reaction Methods 0.000 description 2
- 238000001746 injection moulding Methods 0.000 description 2
- 238000005457 optimization Methods 0.000 description 2
- 238000011056 performance test Methods 0.000 description 2
- 238000006068 polycondensation reaction Methods 0.000 description 2
- 229920002223 polystyrene Polymers 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 238000005303 weighing Methods 0.000 description 2
- TXUICONDJPYNPY-UHFFFAOYSA-N (1,10,13-trimethyl-3-oxo-4,5,6,7,8,9,11,12,14,15,16,17-dodecahydrocyclopenta[a]phenanthren-17-yl) heptanoate Chemical compound C1CC2CC(=O)C=C(C)C2(C)C2C1C1CCC(OC(=O)CCCCCC)C1(C)CC2 TXUICONDJPYNPY-UHFFFAOYSA-N 0.000 description 1
- IUMSDRXLFWAGNT-UHFFFAOYSA-N Dodecamethylcyclohexasiloxane Chemical compound C[Si]1(C)O[Si](C)(C)O[Si](C)(C)O[Si](C)(C)O[Si](C)(C)O[Si](C)(C)O1 IUMSDRXLFWAGNT-UHFFFAOYSA-N 0.000 description 1
- 229910021626 Tin(II) chloride Inorganic materials 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 238000006482 condensation reaction Methods 0.000 description 1
- 239000011258 core-shell material Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000001804 emulsifying effect Effects 0.000 description 1
- 229920006351 engineering plastic Polymers 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- CWAFVXWRGIEBPL-UHFFFAOYSA-N ethoxysilane Chemical compound CCO[SiH3] CWAFVXWRGIEBPL-UHFFFAOYSA-N 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 239000003999 initiator Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 238000003801 milling Methods 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 150000002895 organic esters Chemical class 0.000 description 1
- 125000005375 organosiloxane group Chemical group 0.000 description 1
- 238000000643 oven drying Methods 0.000 description 1
- PIBWKRNGBLPSSY-UHFFFAOYSA-L palladium(II) chloride Chemical compound Cl[Pd]Cl PIBWKRNGBLPSSY-UHFFFAOYSA-L 0.000 description 1
- 238000005453 pelletization Methods 0.000 description 1
- 239000012994 photoredox catalyst Substances 0.000 description 1
- 239000004597 plastic additive Substances 0.000 description 1
- 229920002285 poly(styrene-co-acrylonitrile) Polymers 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000001119 stannous chloride Substances 0.000 description 1
- 235000011150 stannous chloride Nutrition 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000006228 supernatant Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 238000002834 transmittance Methods 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
Abstract
The invention discloses a preparation method of polysiloxane coated polytetrafluoroethylene anti-dripping agent, which comprises the following steps: adding an organic siloxane monomer and a catalyst into the polytetrafluoroethylene emulsion to react, and obtaining polysiloxane/polytetrafluoroethylene emulsion after the reaction is finished; the organic siloxane monomer is a cyclic siloxane monomer; and demulsifying the prepared polysiloxane/polytetrafluoroethylene emulsion, collecting precipitate, drying the precipitate, and crushing to obtain the polysiloxane coated polytetrafluoroethylene anti-dripping agent. According to the invention, polysiloxane is adopted to carry out coating treatment on polytetrafluoroethylene, a solvent is not needed, byproducts are not generated in the reaction process, and the prepared anti-falling agent has good dispersibility and compatibility, is particularly suitable for being used in transparent PC parts, does not influence the transparency of a matrix, and does not have the problem of pocking marks; the preparation method is simple to operate and easy to operate.
Description
Technical Field
The invention relates to the technical field of plastic additives, in particular to a polysiloxane coated polytetrafluoroethylene anti-dripping agent and a preparation method thereof.
Background
PC plastic products are susceptible to melt dripping during combustion, which can spread fire, and in order to improve the flame retardant properties of the plastic, it is necessary to add an anti-dripping agent to the plastic. The common anti-dripping agent is prepared by specially modifying polytetrafluoroethylene Powder (PTFE) with different molecular weights, is added into a formula of the engineering plastic flame retardant, and is formed into a reticular structure by fiberizing polytetrafluoroethylene with high molecular weight under the action of shearing force of a screw rod, so that the melt strength and the bending modulus are increased, the flame retardance of the product is further improved, and dripping caused by combustion is prevented.
Polytetrafluoroethylene used as an antidrip agent mainly has three types: emulsion type, pure powder type, and coated type. Emulsion type anti-dripping agent is an emulsion formed by dispersing polytetrafluoroethylene in water through the action of an emulsifier to form suspension. Because of the moisture, PC absorbs water easily, and the PC is difficult to use, and has high requirements on processing equipment and processing technology. The pure powder type anti-dripping agent is easy to agglomerate, has poor compatibility with other plastics, and has the problem of poor dispersion. The coating type anti-dripping agent is prepared by coating a layer of styrene-acrylonitrile copolymer SAN or polymethyl methacrylate PMMA, polystyrene PS and the like on the outer layer of polytetrafluoroethylene by a chemical method, so that the anti-dripping agent can be well dispersed in polycarbonate PC, acrylonitrile-butadiene-styrene copolymer ABS, polystyrene PS and the like. However, the anti-dripping agent formed by the coating can seriously affect the transparency of the PC, is more prone to generate the problem of pitting, has limited application fields and cannot be used in PC films and high-gloss PC parts.
The silicone material is excellent in flame retardancy imparted to the substrate, improves processability, mechanical properties, heat resistance and the like of the substrate, and is environmentally friendly, and therefore is used as an ideal material for coating PTFE. Compared with other coating materials, the transparent PC film and the high-gloss PC piece are especially used, the transparent PC film and the high-gloss PC piece have small influence on haze, the compatibility of organosilicon and PC is good, and the surface of the PC piece is free from the problem of pitting.
Patent application number CN 201811055660.4 discloses an anti-dripping agent containing PTFE and organosilicon and a preparation method thereof, which comprises the following specific steps: the preparation method comprises the steps of preparing organopolysiloxane core emulsion, emulsifying the organopolysiloxane emulsion and PTFE emulsion, and then adding coating monomer and initiator to coat the emulsion. The method has complicated reaction process, and the coated monomer has poor compatibility with PC, which can affect the transparency of PC parts.
The patent with the application number of CN 202010233099.5 discloses a preparation method of an organosilicon coated polytetrafluoroethylene anti-dripping agent, which comprises the following specific steps: and treating polytetrafluoroethylene dry materials by adopting a mixed solution of palladium chloride and stannous chloride under the ultrasonic condition, generating active groups on the surfaces of the polytetrafluoroethylene dry materials, simultaneously carrying out ultraviolet polymerization, grafting an amide bond on the surfaces of the polytetrafluoroethylene dry materials, and coating the surfaces of polytetrafluoroethylene particles with organosilicon through hydrolysis polycondensation reaction of the organosilicon to prepare the organosilicon-coated polytetrafluoroethylene anti-dripping agent. The method needs to carry out surface grafting treatment on polytetrafluoroethylene, and has the advantages of high process difficulty and complex preparation method.
The patent application number 202210933992.8 discloses a preparation method of a siloxane end-capped coated anti-dripping agent. Uniformly stirring and mixing the coated siloxane monomer and the organic solvent A in a reactor in advance, dropwise adding an acidic catalyst solution or an alkaline catalyst solution, uniformly stirring, heating, and slowly dropwise adding polytetrafluoroethylene emulsion; uniformly stirring and mixing the end-capped siloxane monomer and the organic solvent B in advance, slowly dripping the end-capped siloxane monomer and the organic solvent B into the solution, and uniformly stirring the solution after dripping, adding deionized water, and performing hydrolysis-dehydration condensation reaction to perform end-capping treatment to obtain a product; filtering, washing and drying the product to obtain the siloxane end-capped coated anti-dripping agent; and distilling the filtrate to recover the organic solvent, and then, passing through a drying device to recover the emulsifier powder. In the method, a large amount of solvent is needed to participate in the reaction, and in addition, the used coating is ethoxysilane, ethanol organic solvent is generated by hydrolysis in the reaction process, distillation, recovery and separation are needed after the reaction is finished, so that the production cost is increased, and the yield is low.
The patent with application number 202210767187.2 discloses an organic ester coated anti-dripping agent, which is physically coated and mixed together, has no stable core-shell structure, and is easy to cause PTFE agglomeration after being scattered and sheared by a screw in the use process, so that the use in a transparent PC piece and a highlight piece is affected; in addition, the method does not wash the centrifuged product, so that the residual alkaline emulsifier in the PTFE emulsion is caused, and after the PTFE emulsion is added into PC, the decomposition of PC is affected.
Disclosure of Invention
The technical problems to be solved by the invention are as follows: aiming at the defects existing in the prior art, the polysiloxane coated polytetrafluoroethylene anti-dripping agent and the preparation method thereof are provided, and the polysiloxane is adopted to carry out coating treatment on polytetrafluoroethylene, so that a solvent is not needed, byproducts are not produced in the reaction process, the prepared anti-dripping agent has good dispersibility and compatibility, is particularly suitable for being used in transparent PC (polycarbonate) pieces, does not influence the transparency of a matrix, and does not have the problem of pocking marks; the preparation method is simple to operate and easy to operate.
In order to solve the technical problems, the technical scheme of the invention is as follows:
a preparation method of polysiloxane coated polytetrafluoroethylene anti-dripping agent comprises the following steps:
A. adding an organic siloxane monomer and a catalyst into the polytetrafluoroethylene emulsion to react, and obtaining polysiloxane/polytetrafluoroethylene emulsion after the reaction is finished; the organic siloxane monomer is a cyclic siloxane monomer;
B. and demulsifying the prepared polysiloxane/polytetrafluoroethylene emulsion, collecting precipitate, drying the precipitate, and crushing to obtain the polysiloxane coated polytetrafluoroethylene anti-dripping agent.
As a preferable mode of the technical scheme, in the step A, the temperature of the reaction is 40-90 ℃ and the time is 5-10h.
Preferably, in the above technical scheme, in the step a, the cyclic siloxane monomer is any one or more of hexamethyl cyclotrisiloxane, octamethyl cyclotetrasiloxane, decamethyl cyclopentasiloxane, dodecamethyl cyclotrisiloxane, and tetramethyl tetravinyl cyclotrisiloxane.
As a preferable mode of the technical scheme, in the step A, the solid content of the polytetrafluoroethylene emulsion is 55-65%, the average particle size is 0.01-0.3 mu m, and the viscosity is 5-200 mPa.s; the number average molecular weight of the polytetrafluoroethylene is 300-800 ten thousand.
As a preferable mode of the above technical scheme, in the step a, the mass ratio of the organosiloxane monomer, the catalyst and the polytetrafluoroethylene emulsion is (0.1-0.8): (0.01-0.1): 1.
in the step a, the catalyst is a base catalyst or an acid catalyst; further, the alkali catalyst is one of lithium hydroxide, sodium hydroxide and potassium hydroxide; the acid catalyst is one of dodecylbenzene sulfonic acid and p-toluene sulfonic acid.
As the optimization of the technical scheme, in the step B, one of heating demulsification, centrifugal demulsification, salting-out demulsification, electric demulsification and ultrasonic demulsification is adopted; further, the rotational speed is 3000-5000 rpm during centrifugal demulsification, and the centrifugal time is 20-50min.
As a preferable mode of the above technical scheme, in the step B, one of vacuum drying, freeze drying, air blast drying, spray drying, infrared drying, and microwave drying is adopted in the drying; further, the drying temperature is 70-80 ℃ and the vacuum degree is 0.095MPa when vacuum drying is adopted, and the drying time is 3-5 hours.
As the optimization of the technical scheme, in the step B, one of grinding, ball milling, jet milling and high-speed stirring and powdering is adopted during crushing; further, the crushing pressure is 0.4-0.8MPa, air is working medium, the feeding pressure is 0.5-1.0MPa, and the feeding amount is 40-100 kg/h.
The polysiloxane coated polytetrafluoroethylene anti-dripping agent prepared by the invention is applied to the PC resin material, the additive amount is 0.1-1.0%, the anti-dripping effect can be achieved when the PC is burnt, and meanwhile, the transparency of the PC is not influenced and no pocking marks exist.
Due to the adoption of the technical scheme, the invention has the following beneficial effects:
(1) According to the invention, the polytetrafluoroethylene is coated by the polysiloxane, surface sintering treatment is not needed, and the obtained anti-dripping agent can be uniformly dispersed in various resin materials, so that the problem of dispersing the pure powder type anti-dripping agent is solved.
(2) The polysiloxane coated polytetrafluoroethylene anti-dripping agent obtained by the method is extremely low in water content after polysiloxane coating, emulsion breaking, drying and crushing, and the water resistance of the polysiloxane material overcomes the technical problem of the emulsion type anti-dripping agent in PC application.
(3) Compared with the existing coated polytetrafluoroethylene anti-dripping agent (SAN, PMMA, PS coating), the polysiloxane coated anti-dripping agent provided by the application is excellent in high temperature resistance and low temperature resistance, good in weather resistance, insensitive to light, not easy to oxidize and does not influence the transparency of plastic products.
Detailed Description
The invention is further illustrated below with reference to examples. It is to be understood that these examples are illustrative of the present invention and are not intended to limit the scope of the present invention.
Unless otherwise indicated, all starting materials in the examples herein were purchased commercially; the reactions in the examples were all carried out at room temperature.
Example 1
A. Weighing 500g of polytetrafluoroethylene emulsion (with the particle size of 0.2 mu m, the number average molecular weight of 530 ten thousand and the viscosity of 30 mPa.s) with the solid content, pouring the polytetrafluoroethylene emulsion into a 2L glass flask with a stirrer for stirring, dripping 200g of hexamethylcyclotrisiloxane into the polytetrafluoroethylene emulsion, keeping stirring, weighing 4g of sodium hydroxide into a 200mL beaker, adding 100g of water for stirring until the solution is completely dissolved to obtain a sodium hydroxide solution, dripping the sodium hydroxide solution into the flask with the polytetrafluoroethylene emulsion and the hexamethylcyclotrisiloxane under stirring, heating to 60 ℃ after the dripping, keeping the temperature for 6 hours, keeping stirring, cooling to room temperature, stopping stirring, and pouring out to obtain polysiloxane/polytetrafluoroethylene emulsion;
B. placing polysiloxane/polytetrafluoroethylene emulsion in a centrifuge, centrifuging at 5000 rpm for 30min, taking out supernatant, collecting lower precipitate, placing the collected precipitate in a vacuum drying oven, oven drying at 75deg.C under vacuum degree of 0.095MPa for 4 hr, cooling to room temperature, and taking out to obtain oven-dried product;
C. and (3) putting the dried product into a jet mill, and performing jet milling under the conditions that the milling pressure is 0.5MPa, air is working medium, the feeding pressure is 0.6MPa and the feeding amount is 50 kg/h to obtain the polysiloxane coated polytetrafluoroethylene anti-dripping agent which is marked as C1.
Example 2
This example uses octamethyl cyclotetrasiloxane instead of hexamethylcyclotrisiloxane in example 1, and the other conditions are the same as in example 1, giving a polysiloxane coated polytetrafluoroethylene anti-drip agent, designated C2.
Example 3
In this example, decamethyl cyclopentasiloxane was used instead of hexamethylcyclotrisiloxane in example 1, and the same conditions as in example 1 were used to obtain a polysiloxane coated polytetrafluoroethylene anti-drip agent, designated as C3.
Example 4
In this example, dodecamethyl cyclohexasiloxane was used in place of hexamethylcyclotrisiloxane in example 1, and the same conditions as in example 1 were used to obtain a polysiloxane-coated polytetrafluoroethylene anti-drip agent, designated C4.
Example 5
This example uses tetramethyl tetravinyl cyclotrisiloxane instead of hexamethylcyclotrisiloxane in example 1, and the other conditions are the same as in example 1, giving a polysiloxane coated polytetrafluoroethylene anti-drip agent, designated C5.
Example 6
This example uses lithium hydroxide instead of sodium hydroxide in example 1, and the other conditions are the same as in example 1, to obtain a polysiloxane-coated polytetrafluoroethylene anti-dripping agent, designated as C6.
Example 7
In this example, potassium hydroxide was used in place of sodium hydroxide in example 1 under the same conditions as in example 1 to obtain a polysiloxane-coated polytetrafluoroethylene anti-dripping agent, designated as C7.
Example 8
This example uses dodecylbenzenesulfonic acid instead of sodium hydroxide in example 1, and the same conditions as in example 7, to obtain a polysiloxane-coated polytetrafluoroethylene anti-dripping agent, designated as C8.
Example 9
This example uses p-toluenesulfonic acid instead of sodium hydroxide in example 1, and the same conditions as in example 1, to obtain a polysiloxane-coated polytetrafluoroethylene anti-dripping agent, designated as C9.
Comparative example 1
The comparative example uses pure polytetrafluoroethylene anti-drip agent, designated as D1.
Comparative example 2
The comparative example uses SAN-coated polytetrafluoroethylene anti-dripping agent, wherein the mass fraction of polytetrafluoroethylene is 50%, which is marked as D2.
Comparative example 2
The comparative example was carried out using the anti-dripping agent prepared in example 1 of the prior art 202210767187.2, and was designated as D3.
Application examples
The C1, C2, C3, C4, C5, C6, C7, C8, C9 obtained in the examples were blended with polycarbonate PC (FN 2200 demitsu Kosan Co.Ltd) at an addition level of 0.5%, respectively, using a twin screw extruder (melting zone temperature: 260 ℃ C.), and then subjected to strand drawing and pelletization; blending, bracing and granulating the anti-dripping agent D1 with PC according to the adding amount of 0.3% by using a double-screw extruder (the temperature of a melting section is 260 ℃); blending, bracing and granulating the anti-dripping agent D2 with PC according to the adding amount of 0.6% by using a double-screw extruder (the temperature of a melting section is 260 ℃); performing spline injection molding on the resin particles added with the anti-dripping agent by using an injection molding machine (the mold temperature is 265 ℃), and performing appearance evaluation, anti-dripping performance test and haze test on the spline; wherein, the anti-dripping performance test adopts an UL94 horizontal vertical burning instrument to carry out vertical burning; the haze test is carried out by adopting a light transmittance haze tester; appearance evaluation by observing the surface pitting condition (counting the number of pitting in a 3 x 3cm area) after casting the material.
TABLE 1
In the above examples and comparative examples, the amount of the anti-dripping agent added to the resin was 0.3% by mass of the pure polytetrafluoroethylene. Compared with the comparative example, the PTFE is coated by the polysiloxane, the type of the polysiloxane is effectively selected, the prepared coated anti-dripping agent has good dispersibility in PC base materials, and the obtained particles have good transparency. The polysiloxane coated polytetrafluoroethylene anti-dripping agent provided by the invention has no influence on the transparency of PC, and the samples of the comparative example, in which the anti-dripping agent is added into PC, have serious blushing and fogging. This is mainly due to the fact that the polysiloxane coated polytetrafluoroethylene can be uniformly dispersed in the PC and the sample does not suffer from the pitting problem. The haze varies from one embodiment to another because of the different cyclic siloxanes and catalysts reactivity and thus the speed, coating rate and uniformity of coating during polycondensation coating.
In conclusion, the polysiloxane coated polytetrafluoroethylene anti-dripping agent prepared by the invention solves the problems of transparency and pocking marks, and has wider application range, especially for transparent PC parts and high-light PC parts.
Further, it is understood that various changes and modifications may be made by those skilled in the art after reading the teachings of the present invention, and such equivalents are intended to fall within the scope of the claims appended hereto.
Claims (7)
1. The preparation method of the polysiloxane coated polytetrafluoroethylene anti-dripping agent is characterized by comprising the following steps of:
A. adding an organic siloxane monomer and a catalyst into the polytetrafluoroethylene emulsion to react, and obtaining polysiloxane/polytetrafluoroethylene emulsion after the reaction is finished; the organic siloxane monomer is a cyclic siloxane monomer; the cyclic siloxane monomer is any one or a mixture of more than one of hexamethyl cyclotrisiloxane, octamethyl cyclotetrasiloxane, decamethyl cyclopentasiloxane, dodecamethyl cyclotrisiloxane and tetramethyl tetravinyl cyclotrisiloxane; the solid content of the polytetrafluoroethylene emulsion is 55-65%, and the catalyst is an alkali catalyst or an acid catalyst; the mass ratio of the organic siloxane monomer to the catalyst to the polytetrafluoroethylene emulsion is (0.1-0.8): (0.01-0.1): 1, a step of;
B. and demulsifying the prepared polysiloxane/polytetrafluoroethylene emulsion, collecting precipitate, drying the precipitate, and crushing to obtain the polysiloxane coated polytetrafluoroethylene anti-dripping agent.
2. The method for preparing the polysiloxane-coated polytetrafluoroethylene anti-dripping agent according to claim 1, wherein the method comprises the following steps: in the step A, the temperature of the reaction is 40-90 ℃ and the time is 5-10h.
3. The method for preparing the polysiloxane-coated polytetrafluoroethylene anti-dripping agent according to claim 1, wherein the method comprises the following steps: in the step A, the average grain diameter of polytetrafluoroethylene in the polytetrafluoroethylene emulsion is 0.01-0.3 mu m, and the number average molecular weight of polytetrafluoroethylene in the polytetrafluoroethylene emulsion is 300-800 ten thousand; the viscosity of the polytetrafluoroethylene emulsion is 5-200mPa.s.
4. The method for preparing the polysiloxane-coated polytetrafluoroethylene anti-dripping agent according to claim 1, wherein the method comprises the following steps: in the step A, the alkali catalyst is one of lithium hydroxide, sodium hydroxide and potassium hydroxide; the acid catalyst is one of dodecylbenzene sulfonic acid and p-toluene sulfonic acid.
5. The method for preparing the polysiloxane-coated polytetrafluoroethylene anti-dripping agent according to claim 1, wherein the method comprises the following steps: in the step B, one of heating demulsification, centrifugal demulsification, salting-out demulsification, electric demulsification and ultrasonic demulsification is adopted in demulsification; the rotational speed is 3000-5000 rpm, and the centrifugation time is 20-50min.
6. The method for preparing the polysiloxane-coated polytetrafluoroethylene anti-dripping agent according to claim 1, wherein the method comprises the following steps: in the step B, one of vacuum drying, freeze drying, forced air drying, spray drying, infrared drying and microwave drying is adopted during drying; the drying temperature is 70-80 ℃ and the vacuum degree is 0.095MPa when vacuum drying is adopted, and the drying time is 3-5 hours.
7. The method for preparing the polysiloxane-coated polytetrafluoroethylene anti-dripping agent according to claim 1, wherein the method comprises the following steps: in the step B, one of grinding, ball milling, jet milling and high-speed stirring and powdering is adopted during crushing; the crushing pressure is 0.4-0.8MPa, air is working medium, the feeding pressure is 0.5-1.0MPa, and the feeding amount is 40-100 kg/h.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1837262A (en) * | 2006-04-24 | 2006-09-27 | 广州吉必时科技实业有限公司 | Process for synthesis of polysiloxane |
| WO2007119742A1 (en) * | 2006-04-14 | 2007-10-25 | Idemitsu Kosan Co., Ltd. | Polycarbonate resin composition and molded plate obtained therefrom |
| CN114933770A (en) * | 2022-06-30 | 2022-08-23 | 浙江佳华精化股份有限公司 | Coated polytetrafluoroethylene anti-dripping agent and preparation method thereof |
| CN115232313A (en) * | 2022-08-04 | 2022-10-25 | 广东知塑新材料有限公司 | Preparation method of siloxane end-capped coated anti-dripping agent |
| CN116656130A (en) * | 2023-06-06 | 2023-08-29 | 浙江佳华精化股份有限公司 | Self-compatibilizing flame-retardant organic silicon thermoplastic elastomer material and preparation method thereof |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2007119742A1 (en) * | 2006-04-14 | 2007-10-25 | Idemitsu Kosan Co., Ltd. | Polycarbonate resin composition and molded plate obtained therefrom |
| CN1837262A (en) * | 2006-04-24 | 2006-09-27 | 广州吉必时科技实业有限公司 | Process for synthesis of polysiloxane |
| CN114933770A (en) * | 2022-06-30 | 2022-08-23 | 浙江佳华精化股份有限公司 | Coated polytetrafluoroethylene anti-dripping agent and preparation method thereof |
| CN115232313A (en) * | 2022-08-04 | 2022-10-25 | 广东知塑新材料有限公司 | Preparation method of siloxane end-capped coated anti-dripping agent |
| CN116656130A (en) * | 2023-06-06 | 2023-08-29 | 浙江佳华精化股份有限公司 | Self-compatibilizing flame-retardant organic silicon thermoplastic elastomer material and preparation method thereof |
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