CN118108931A - Low-end carboxyl polybutylene terephthalate and preparation method thereof - Google Patents
Low-end carboxyl polybutylene terephthalate and preparation method thereof Download PDFInfo
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- 229920001707 polybutylene terephthalate Polymers 0.000 title claims abstract description 64
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 title claims abstract description 38
- 238000002360 preparation method Methods 0.000 title claims abstract description 27
- -1 polybutylene terephthalate Polymers 0.000 title claims abstract description 19
- 239000003054 catalyst Substances 0.000 claims abstract description 93
- 239000002131 composite material Substances 0.000 claims abstract description 50
- 238000006068 polycondensation reaction Methods 0.000 claims abstract description 42
- 239000000203 mixture Substances 0.000 claims abstract description 36
- 238000005886 esterification reaction Methods 0.000 claims abstract description 33
- 239000007787 solid Substances 0.000 claims abstract description 27
- KKEYFWRCBNTPAC-UHFFFAOYSA-N Terephthalic acid Chemical compound OC(=O)C1=CC=C(C(O)=O)C=C1 KKEYFWRCBNTPAC-UHFFFAOYSA-N 0.000 claims abstract description 20
- WERYXYBDKMZEQL-UHFFFAOYSA-N butane-1,4-diol Chemical compound OCCCCO WERYXYBDKMZEQL-UHFFFAOYSA-N 0.000 claims abstract description 20
- 239000002608 ionic liquid Substances 0.000 claims abstract description 20
- 230000032050 esterification Effects 0.000 claims abstract description 19
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 17
- 150000003606 tin compounds Chemical class 0.000 claims abstract description 14
- 229910019142 PO4 Inorganic materials 0.000 claims abstract description 12
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims abstract description 12
- 229910052783 alkali metal Inorganic materials 0.000 claims abstract description 12
- 150000001340 alkali metals Chemical class 0.000 claims abstract description 12
- 239000010452 phosphate Substances 0.000 claims abstract description 12
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 claims abstract description 12
- 150000001413 amino acids Chemical class 0.000 claims abstract description 10
- 239000002994 raw material Substances 0.000 claims abstract description 6
- 230000035484 reaction time Effects 0.000 claims abstract description 6
- 238000006243 chemical reaction Methods 0.000 claims description 32
- 238000005470 impregnation Methods 0.000 claims description 32
- 238000000034 method Methods 0.000 claims description 24
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 22
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 20
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 18
- 238000001035 drying Methods 0.000 claims description 17
- YHWCPXVTRSHPNY-UHFFFAOYSA-N butan-1-olate;titanium(4+) Chemical compound [Ti+4].CCCC[O-].CCCC[O-].CCCC[O-].CCCC[O-] YHWCPXVTRSHPNY-UHFFFAOYSA-N 0.000 claims description 16
- KSBAEPSJVUENNK-UHFFFAOYSA-L tin(ii) 2-ethylhexanoate Chemical compound [Sn+2].CCCCC(CC)C([O-])=O.CCCCC(CC)C([O-])=O KSBAEPSJVUENNK-UHFFFAOYSA-L 0.000 claims description 16
- 238000001354 calcination Methods 0.000 claims description 15
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 claims description 14
- 239000007788 liquid Substances 0.000 claims description 14
- QDRKDTQENPPHOJ-UHFFFAOYSA-N sodium ethoxide Chemical compound [Na+].CC[O-] QDRKDTQENPPHOJ-UHFFFAOYSA-N 0.000 claims description 13
- 238000001816 cooling Methods 0.000 claims description 12
- IAZSXUOKBPGUMV-UHFFFAOYSA-N 1-butyl-3-methyl-1,2-dihydroimidazol-1-ium;chloride Chemical compound [Cl-].CCCC[NH+]1CN(C)C=C1 IAZSXUOKBPGUMV-UHFFFAOYSA-N 0.000 claims description 10
- 239000000377 silicon dioxide Substances 0.000 claims description 8
- 239000002245 particle Substances 0.000 claims description 7
- 239000003208 petroleum Substances 0.000 claims description 7
- XZZNDPSIHUTMOC-UHFFFAOYSA-N triphenyl phosphate Chemical compound C=1C=CC=CC=1OP(OC=1C=CC=CC=1)(=O)OC1=CC=CC=C1 XZZNDPSIHUTMOC-UHFFFAOYSA-N 0.000 claims description 7
- 239000011148 porous material Substances 0.000 claims description 6
- MFRIHAYPQRLWNB-UHFFFAOYSA-N sodium tert-butoxide Chemical compound [Na+].CC(C)(C)[O-] MFRIHAYPQRLWNB-UHFFFAOYSA-N 0.000 claims description 6
- VXUYXOFXAQZZMF-UHFFFAOYSA-N titanium(IV) isopropoxide Chemical compound CC(C)O[Ti](OC(C)C)(OC(C)C)OC(C)C VXUYXOFXAQZZMF-UHFFFAOYSA-N 0.000 claims description 6
- HVLLSGMXQDNUAL-UHFFFAOYSA-N triphenyl phosphite Chemical compound C=1C=CC=CC=1OP(OC=1C=CC=CC=1)OC1=CC=CC=C1 HVLLSGMXQDNUAL-UHFFFAOYSA-N 0.000 claims description 4
- OIWSIWZBQPTDKI-UHFFFAOYSA-N 1-butyl-3-methyl-2h-imidazole;hydrobromide Chemical compound [Br-].CCCC[NH+]1CN(C)C=C1 OIWSIWZBQPTDKI-UHFFFAOYSA-N 0.000 claims description 3
- JGFBRKRYDCGYKD-UHFFFAOYSA-N dibutyl(oxo)tin Chemical compound CCCC[Sn](=O)CCCC JGFBRKRYDCGYKD-UHFFFAOYSA-N 0.000 claims description 3
- 238000010992 reflux Methods 0.000 claims description 3
- 238000002791 soaking Methods 0.000 claims description 3
- 238000003756 stirring Methods 0.000 claims description 3
- UKLDJPRMSDWDSL-UHFFFAOYSA-L [dibutyl(dodecanoyloxy)stannyl] dodecanoate Chemical compound CCCCCCCCCCCC(=O)O[Sn](CCCC)(CCCC)OC(=O)CCCCCCCCCCC UKLDJPRMSDWDSL-UHFFFAOYSA-L 0.000 claims description 2
- 239000012975 dibutyltin dilaurate Substances 0.000 claims description 2
- 238000007598 dipping method Methods 0.000 claims description 2
- 238000000967 suction filtration Methods 0.000 claims description 2
- 125000000999 tert-butyl group Chemical group [H]C([H])([H])C(*)(C([H])([H])[H])C([H])([H])[H] 0.000 claims description 2
- DQWPFSLDHJDLRL-UHFFFAOYSA-N triethyl phosphate Chemical compound CCOP(=O)(OCC)OCC DQWPFSLDHJDLRL-UHFFFAOYSA-N 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 abstract description 10
- 239000000463 material Substances 0.000 abstract description 5
- 235000012239 silicon dioxide Nutrition 0.000 abstract description 5
- 230000015572 biosynthetic process Effects 0.000 abstract description 3
- 238000007086 side reaction Methods 0.000 abstract description 3
- 239000005543 nano-size silicon particle Substances 0.000 abstract description 2
- 238000006116 polymerization reaction Methods 0.000 abstract description 2
- 238000003786 synthesis reaction Methods 0.000 abstract description 2
- 230000015556 catabolic process Effects 0.000 abstract 1
- 238000006731 degradation reaction Methods 0.000 abstract 1
- 229920001634 Copolyester Polymers 0.000 description 22
- 239000000243 solution Substances 0.000 description 19
- 238000010438 heat treatment Methods 0.000 description 18
- 230000000052 comparative effect Effects 0.000 description 15
- 125000003118 aryl group Chemical group 0.000 description 10
- 239000013067 intermediate product Substances 0.000 description 10
- 238000005303 weighing Methods 0.000 description 9
- 238000002156 mixing Methods 0.000 description 8
- 230000000694 effects Effects 0.000 description 6
- 239000011261 inert gas Substances 0.000 description 6
- 239000012299 nitrogen atmosphere Substances 0.000 description 6
- 235000019441 ethanol Nutrition 0.000 description 5
- 238000007654 immersion Methods 0.000 description 5
- 230000003197 catalytic effect Effects 0.000 description 4
- 239000007809 chemical reaction catalyst Substances 0.000 description 4
- 229920006351 engineering plastic Polymers 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- 238000005265 energy consumption Methods 0.000 description 3
- 229910021426 porous silicon Inorganic materials 0.000 description 3
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000006555 catalytic reaction Methods 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 2
- 239000011259 mixed solution Substances 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 230000002195 synergetic effect Effects 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 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 1
- 238000005618 Fries rearrangement reaction Methods 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 150000004650 carbonic acid diesters Chemical class 0.000 description 1
- 125000002915 carbonyl group Chemical group [*:2]C([*:1])=O 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010292 electrical insulation Methods 0.000 description 1
- 125000004185 ester group Chemical group 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000003063 flame retardant Substances 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 239000000178 monomer Substances 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- 229920001225 polyester resin Polymers 0.000 description 1
- 239000004645 polyester resin Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 150000003384 small molecules Chemical class 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 description 1
- 229920001187 thermosetting polymer Polymers 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 238000005809 transesterification reaction Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Landscapes
- Polyesters Or Polycarbonates (AREA)
Abstract
The invention belongs to the field of synthesis of biodegradable materials, and discloses low-end carboxyl polybutylene terephthalate and a preparation method thereof, aiming at the problems of low content of end carboxyl of PBT, low raw material utilization rate, long reaction time and the like in the prior art. The nano silicon dioxide is used as a carrier, titanate, tin compounds, alkali metal catalysts and phosphate are reacted under certain conditions to prepare the nano solid composite catalyst, and then the nano solid composite catalyst is mixed with amino acid ionic liquid to obtain the composite catalyst composition. The composite catalyst composition, terephthalic acid and 1, 4-butanediol are subjected to esterification, pre-polycondensation and final polycondensation in sequence to prepare the low-end carboxyl PBT. The composite catalyst composition can effectively reduce the content of carboxyl end groups, improve the esterification rate, shorten the esterification time, reduce thermal degradation, improve the polymerization rate, shorten the production period, reduce the formation of side reactions and have wide application prospect.
Description
Technical Field
The invention belongs to the field of synthesis of biodegradable materials, and particularly relates to low-end carboxyl polybutylene terephthalate and a preparation method thereof.
Background
Polybutylene terephthalate (PBT) is a common high-molecular polyester resin material, and can be widely applied to various fields of electric appliances, household appliances, aircraft manufacturing, transportation and the like. Compared with various metal materials and thermosetting engineering plastics, the PBT engineering plastics have the advantages of mature production process, easy production and relatively low investment cost. The PBT has good mechanical properties, and the symmetrical molecular structure can realize tight stacking; has high crystallinity and can be rapidly crystallized at low temperature. The PBT part is easy to flow and form during processing, has a short forming period and can reduce production cost. And PBT has the advantages of moisture resistance, wear resistance, oil resistance and the like, and has small creep deformation. Since PBT contains crystalline and amorphous portions, it is easily modified by adding other substances. The production energy consumption of the PBT engineering plastic is relatively low, and the PBT engineering plastic is beneficial to relieving energy shortage. PBT is easy to flame retardant, and can meet the UL 94V-0 level requirement.
In production, besides indexes such as intrinsic viscosity, melting point and hue, the terminal carboxyl content is also commonly used for reflecting the quality of the PBT slice, and the terminal carboxyl content is too high, so that acidolysis reaction on ester groups in reactants is more, and the problem of too fast acidolysis in the large-scale industrial production process can be generated. And along with acidolysis of the material, the content of carboxyl ends is increased, and the electrical insulation and thermal stability of the product are directly affected. Therefore, the content of the carboxyl end group must be controlled within a certain process requirement, however, the content of the carboxyl end group is limited by various parameter conditions, the regulation and control are complicated, and the law is difficult to find. Therefore, how to reduce the carboxyl end group content of the PBT material, improve the utilization rate of raw materials, reduce the reaction time and improve the yield of the product is a technical problem to be solved urgently.
Disclosure of Invention
Aiming at the defects existing in the prior art, the invention provides the low-end carboxyl polybutylene terephthalate (PBT) and the preparation method thereof, wherein the low-end carboxyl polybutylene terephthalate (PBT) is prepared under the catalysis of the novel composite catalyst composition, the preparation method can obviously shorten the esterification reaction time, improve the utilization rate of raw materials, relieve the problem of high energy consumption of polyester caused by long production period, and the prepared PBT can effectively reduce the content of end carboxyl.
In a first aspect, the invention discloses a preparation method of low-end carboxyl polybutylene terephthalate (PBT), which specifically comprises the following steps: adding terephthalic acid, 1, 4-butanediol and a composite catalyst composition into a reaction kettle together, and obtaining the PBT copolyester through esterification, pre-polycondensation and final polycondensation, wherein the dosage of the composite catalyst composition is 0.05-0.5% of the total weight of raw materials of a reaction system.
Further, the molar content ratio of the 1, 4-butanediol to the terephthalic acid is 1.3-1.5:1.
The reaction formula of the PBT copolyester is shown as follows:
；
Further, the composite catalyst composition is added prior to the esterification reaction.
Further, the esterification reaction temperature is 220-235 ℃, and the reaction time is 5-8h.
Further, during the pre-polycondensation reaction, firstly heating to not lower than 240 ℃ to perform the pre-polycondensation reaction for not less than 1h; then gradually increasing the vacuum degree in the reaction kettle, and maintaining the pressure for not less than 1h when the vacuum degree is not more than 500 Pa.
Further, the final polycondensation reaction is carried out for at least 1 hour under the conditions that the pressure of a vacuum environment is less than 180Pa and the temperature is 250 ℃.
Further, the air in the reaction kettle is pumped out by adopting an inert gas substitution method before esterification or transesterification, and the reaction is carried out in a nitrogen atmosphere.
The polybutylene terephthalate copolyester prepared by the method has the excellent performances of 0.8-1.2g/dL viscosity, terminal carboxyl content of <20mol/t, tensile strength of >44.6MPa and impact strength of >21.5kJ/m 2.
Further, the composite catalyst composition comprises a nano-scale solid composite catalyst and an amino acid ionic liquid; the nano-scale solid composite catalyst comprises, by mass, 8 parts of an amino acid ionic liquid and 3 parts of a nano-scale solid composite catalyst;
The nano-scale solid composite catalyst takes nano silicon dioxide as a carrier, and sequentially coats titanate, tin compounds, alkali metal catalysts and phosphate from inside to outside;
the catalyst is prepared by sequentially placing a carrier in a titanate solution, a tin compound solution, an alkali metal catalyst and phosphate mixed solution for equal volume impregnation, drying and calcination.
Further, the mol ratio of the tin compound to the titanate is 1:1-1:2; the mol ratio of the tin compounds to the phosphate is 1:1-1:5; the mol ratio of the tin compound to the alkali metal catalyst is 1:1-1:2.
Further, the titanate is at least one of diethyl titanate, tetra-tert-butyl titanate, tetrabutyl titanate and tetraisopropyl titanate;
the tin compound is at least one of stannous octoate, dibutyl tin oxide and dibutyl tin dilaurate;
the phosphate is at least one of triphenyl phosphite, triphenyl phosphate and triethyl phosphate;
The alkali metal catalyst is at least one of sodium ethoxide and sodium tert-butoxide;
Further, the amino acid ionic liquid is selected from one of 1-butyl-3-methylimidazole chloride salt and 1-butyl-3-methylimidazole bromide salt.
Further, the nano SiO 2 carrier is a porous silica sphere, the pore diameter of the porous silica sphere is 0.1-10nm, and the particle size of the nano SiO 2 carrier is 1-6mm.
The composite catalyst composition is prepared by adopting the following method, and the nanoscale solid composite catalyst and the amino acid ionic liquid are prepared according to the mass ratio of 8:3, uniformly mixing the components in proportion to obtain the novel composite catalyst composition.
The nano-scale solid composite catalyst is prepared by the following method:
S1, placing a pretreated nano SiO 2 carrier in a first impregnating solution for impregnation, drying and calcining according to an isovolumetric impregnation method to obtain a first modified carrier; the first impregnating solution is obtained by fully dissolving titanate in absolute methanol;
S2, according to an isovolumetric impregnation method, the first modified carrier treated in the step S1 is placed in a second impregnation liquid for impregnation, drying and calcination, so as to obtain a second modified carrier; the second impregnating solution is obtained by dissolving a tin compound in petroleum ether fully;
S3, according to an isovolumetric impregnation method, the second modified carrier treated in the step S2 is placed in a third impregnation liquid for impregnation and reaction, and after cooling, suction filtration and drying treatment, the nano-scale solid composite catalyst is obtained; the third impregnating solution is prepared by adding an alkali metal catalyst and phosphate into absolute ethyl alcohol, and carrying out reflux stirring reaction for not less than 6 hours at 50-60 ℃.
Further, the pretreatment process of the nano SiO 2 carrier comprises the following steps: and (3) drying the nano SiO 2 carrier at 100 ℃ for not less than 5 hours, and then calcining at not less than 350 ℃ for not less than 6 hours.
Further, in the step S1, the soaking time of the nano SiO 2 carrier is not less than 6 hours, and then the nano SiO 2 carrier is dried in an oven at the temperature of not less than 100 ℃ for not less than 18 hours; heating to 550 ℃ at a speed of 10 ℃/min, and keeping the calcination time at not lower than 550 ℃ for not less than 6 hours;
Further, in the step S2, the dipping time is not less than 6 hours, and then the drying is carried out in an oven at the temperature not lower than 100 ℃ for not less than 18 hours; heating to 550 ℃ at a speed of 10 ℃/min, and keeping the calcination time at not lower than 550 ℃ for not less than 6 hours;
In step S3, an alkali metal catalyst and a phosphate are added into absolute ethanol, and the mixture is refluxed and stirred at 60 ℃ for a period of time of 8 hours.
Further, in the step S3, the soaking time is not less than 6 hours, and then the drying is performed in an oven at not less than 100 ℃ for not less than 18 hours.
The beneficial effects are that: (1) The invention adopts amino acid ionic liquid as catalyst to better activate carbonyl and hydroxyl of carbonic acid diester and dihydroxyl compound, improves the reaction esterification rate of polymerized monomers, reduces esterification time, and simultaneously, in the polycondensation process, the ionic liquid catalyst can be completely degraded into small molecules to be removed by vacuum, thereby reducing residual quantity. The nano-scale solid composite catalyst has excellent thermal stability, can have a certain synergistic effect in the esterification stage, can effectively inhibit fries rearrangement reaction, reduces the occurrence of side reaction, and still maintains higher reaction activity in the polycondensation stage.
(2) The composite catalyst composition selected by the invention has excellent catalytic performance and good thermal stability, improves the esterification rate in a short time, reduces the generation of tetrahydrofuran in the esterification stage, optimizes the production process, reduces the waste of raw materials, can reduce the consumption in the aspect of energy, and can greatly shorten the production period of the PBT.
(3) The invention can rapidly prepare the polybutylene terephthalate PBT with high viscosity (0.8-1.2 g/dL) and low carboxyl end content (< 20 mol/t) under the synergistic effect of the high-efficiency composite catalyst, has excellent mechanical properties (tensile strength >44.6MPa and impact strength >21.5kJ/m 2), has excellent comprehensive properties, has higher mechanical properties compared with the PBT taking pure tetrabutyl titanate as the catalyst, and has great application prospect in the field of plastic packaging.
Detailed Description
The technical scheme of the present invention is described below by using specific examples, but the scope of the present invention is not limited thereto:
The intrinsic viscosity and melt index in the examples below were determined as follows:
Intrinsic viscosity: 0.2g of aromatic PBT copolyester is dissolved in 20ml of mixed solution of phenol-1, 2-tetrachloroethane with the mass ratio of 3:2, and the calculation formula of the intrinsic viscosity is:
；
；
；
Wherein: η r: relative viscosity, η sp: build viscosity, t 0: solvent run-off time, t 1: polymer solution run-off time, c: polymer solution concentration;
Yield = 100% x actual yield of target product/theoretical yield of target product.
Carboxyl end group content: measurements were made according to GB/T14190-2017, experimental method A for the 5.4 carboxyl end group.
Testing of tensile strength and elongation at break reference is made to the determination of plastics-tensile properties in GB/T1040.1-2006. At least 5 parallel samples were tested.
Impact strength: standard ASTM D256 standard is used. The sample strip model with cantilever beam notch impact strength is as follows: (125.0+ -5.0) mm (13.0+ -0.5) mm (3.2+ -0.2) mm, notch machined, notch depth (2.6+ -0.2) mm.
Example 1 (preparation of composite catalyst composition)
(1) Weighing 100g of nano SiO 2 carrier, placing the carrier in an oven with the temperature set to be 100 ℃ for drying for 5 hours, and then roasting the carrier for 6 hours in a muffle furnace at 350 ℃; the nano SiO 2 is a porous silica sphere, the pore diameter is 0.1nm, and the particle size is 1mm.
(2) Tetrabutyl titanate (34.0 g,0.1 mol) was weighed accurately, and a certain amount of anhydrous methanol was taken and sufficiently dissolved to obtain an impregnation liquid (isovolumetric impregnation).
(3) The support of step (1) was immersed in the immersion liquid of step 2 for 6 hours, and then dried in an oven at 100℃for 18 hours.
(4) The resulting modified support of (3) was calcined in a muffle furnace at a rate of 10deg.C/min for 6h at 550 ℃.
(5) Stannous octoate (40.5 g,0.1 mol) was weighed and dissolved in a certain amount of petroleum ether to obtain an impregnating solution (isovolumetric impregnation), and the modified support in (4) was immersed in the solution for 6 hours, and finally dried in an oven at 100 ℃ for 18 hours.
(6) Calcining the catalyst obtained in step (5) in a muffle furnace at 550 ℃ for 6h, and cooling to room temperature to obtain the catalyst.
(7) The catalyst obtained in the step (6) is dissolved with sodium ethoxide (6.8 g,0.1 mol) and triphenyl phosphate (32.6 g,0.1 mol) in a certain amount of ethanol to be mixed, the mixture is refluxed and stirred at 60 ℃ for 8 hours to obtain an intermediate product, and the intermediate product is filtered after stopping heating and fully cooling, and is dried in vacuum to obtain a white solid.
(8) Weighing 3-5g of white solid, adding 1-butyl-3-methylimidazole chloride ionic liquid according to the mass ratio of 8:3, and uniformly mixing to obtain the novel composite catalyst composition C 1.
Example 2 (preparation of composite catalyst composition)
(1) Weighing 100g of nano SiO 2 carrier, placing the carrier in an oven with the temperature set to be 100 ℃ for drying for 5 hours, and then roasting the carrier for 6 hours in a muffle furnace at 350 ℃; the nano SiO 2 is a porous silicon dioxide sphere, the aperture is 10nm, and the particle size is 6mm.
(2) Tetraisopropyl titanate (28.4 g,0.1 mol) was weighed accurately, and a certain amount of anhydrous methanol was taken and dissolved sufficiently to obtain an impregnating solution (isovolumetric impregnation).
(3) The support of step (1) was immersed in the immersion liquid of step 2 for 6 hours, and then dried in an oven at 100℃for 18 hours.
(4) The resulting modified support of (3) was calcined in a muffle furnace at a rate of 10deg.C/min for 6h at 550 ℃.
(5) Dibutyl tin oxide (24.8 g,0.1 mol) was weighed and dissolved in a certain amount of petroleum ether to obtain an impregnating solution (isovolumetric impregnation), and the modified support in (4) was immersed in the solution for 6 hours, and finally dried in an oven at 100 ℃ for 18 hours.
(6) Calcining the catalyst obtained in step (5) in a muffle furnace at 550 ℃ for 6h, and cooling to room temperature to obtain the catalyst.
(7) The catalyst obtained in the step (6) is dissolved with sodium ethoxide (6.8, 0.1 mol) and triphenyl phosphate (32.6 g,0.1 mol) in a certain amount of ethanol to be mixed, the mixture is refluxed and stirred at 60 ℃ for 8 hours to obtain an intermediate product, and the intermediate product is filtered after stopping heating and fully cooling, and is dried in vacuum to obtain a white solid.
(8) 3-5G of white solid is weighed according to the mass ratio of 8:3, and 1-butyl-3-methylimidazole chloride ionic liquid is added for uniform mixing, thus obtaining the novel composite catalyst composition C 2.
Example 3 (preparation of composite catalyst composition)
(1) Weighing 100g of nano SiO 2 carrier, placing the carrier in an oven with the temperature set to be 100 ℃ for drying for 5 hours, and then roasting the carrier for 6 hours in a muffle furnace at 350 ℃; the nano SiO 2 is a porous silica sphere, the pore diameter is 5nm, and the particle size is 3mm.
(2) Diethyl titanate (18.9 g,0.1 mol) was weighed accurately, and a certain amount of absolute ethanol was taken and sufficiently dissolved to obtain an impregnation liquid (isovolumetric impregnation).
(3) The support of step (1) was immersed in the immersion liquid of step 2 for 6 hours, and then dried in an oven at 100℃for 18 hours.
(4) The resulting modified support of (3) was calcined in a muffle furnace at a rate of 10deg.C/min for 6h at 550 ℃.
(5) Stannous octoate (40.5 g,0.1 mol) was weighed and dissolved in a certain amount of petroleum ether to obtain an impregnating solution (isovolumetric impregnation), and the modified support in (4) was immersed in the solution for 6 hours, and finally dried in an oven at 100 ℃ for 18 hours.
(6) Calcining the catalyst obtained in step (5) in a muffle furnace at 550 ℃ for 6h, and cooling to room temperature to obtain the catalyst.
(7) The catalyst obtained in the step (6) is dissolved with sodium tert-butoxide (9.6 g,0.1 mol) and triphenyl phosphate (32.6 g,0.1 mol) in a certain amount of ethanol to be mixed, the mixture is refluxed and stirred at 60 ℃ for 8 hours to obtain an intermediate product, and the intermediate product is filtered after stopping heating and fully cooling, and is dried in vacuum to obtain a white solid.
(8) Weighing 3-5g of white solid according to the mass ratio of 8:3, adding 1-butyl-3-methylimidazole bromide ionic liquid, and uniformly mixing to obtain the novel composite catalyst composition C 3.
Example 4 (preparation of composite catalyst composition)
(1) Weighing 100g of nano SiO 2 carrier, placing the carrier in an oven with the temperature set to be 100 ℃ for drying for 5 hours, and then roasting the carrier for 6 hours in a muffle furnace at 350 ℃; the nano SiO 2 is a porous silicon dioxide sphere, the pore diameter is 2nm, and the particle size is 2mm.
(2) Tetrabutyl titanate (34.0 g,0.1 mol) was weighed accurately, and a certain amount of anhydrous methanol was taken and sufficiently dissolved to obtain an impregnation liquid (isovolumetric impregnation).
(3) The support of step (1) was immersed in the immersion liquid of step 2 for 6 hours, and then dried in an oven at 100℃for 18 hours.
(4) The resulting modified support of (3) was calcined in a muffle furnace at a rate of 10deg.C/min for 6h at 550 ℃.
(5) Stannous octoate (40.5 g,0.1 mol) was weighed and dissolved in a certain amount of petroleum ether to obtain an impregnating solution (isovolumetric impregnation), and the modified support in (4) was immersed in the solution for 6 hours, and finally dried in an oven at 100 ℃ for 18 hours.
(6) Calcining the catalyst obtained in step (5) in a muffle furnace at 550 ℃ for 6h, and cooling to room temperature to obtain the catalyst.
(7) The catalyst obtained in the step (6) is dissolved with sodium ethoxide (6.8 g,0.1 mol) and triphenyl phosphate (32.6 g,0.1 mol) in a certain amount of ethanol to be mixed, the mixture is refluxed and stirred at 60 ℃ for 8 hours to obtain an intermediate product, and the intermediate product is filtered after stopping heating and fully cooling, and is dried in vacuum to obtain a white solid.
(8) Weighing 3-5g of white solid, adding 1-butyl-3-methylimidazole chloride ionic liquid according to the mass ratio of 9:1, and uniformly mixing to obtain the novel composite catalyst composition C 4.
Example 5 (preparation of composite catalyst composition)
(1) Weighing 100g of nano SiO 2 carrier, placing the carrier in an oven with the temperature set to be 100 ℃ for drying for 5 hours, and then roasting the carrier for 6 hours in a muffle furnace at 350 ℃; the nano SiO 2 is a porous silicon dioxide sphere, the pore diameter is 2nm, and the particle size is 2mm.
(2) Tetrabutyl titanate (34.0 g,0.1 mol) was weighed accurately, and a certain amount of anhydrous methanol was taken and sufficiently dissolved to obtain an impregnation liquid (isovolumetric impregnation).
(3) The support of step (1) was immersed in the immersion liquid of step 2 for 6 hours, and then dried in an oven at 100℃for 18 hours.
(4) The resulting modified support of (3) was calcined in a muffle furnace at a rate of 10deg.C/min for 6h at 550 ℃.
(5) Stannous octoate (40.5 g,0.1 mol) was weighed and dissolved in a certain amount of petroleum ether to obtain an impregnating solution (isovolumetric impregnation), and the modified support in (4) was immersed in the solution for 6 hours, and finally dried in an oven at 100 ℃ for 18 hours.
(6) Calcining the catalyst obtained in step (5) in a muffle furnace at 550 ℃ for 6h, and cooling to room temperature to obtain the catalyst.
(7) The catalyst obtained in the step (6) is dissolved with sodium ethoxide (6.8 g,0.1 mol) and triphenyl phosphate (32.6 g,0.1 mol) in a certain amount of ethanol to be mixed, the mixture is refluxed and stirred at 60 ℃ for 8 hours to obtain an intermediate product, and the intermediate product is filtered after stopping heating and fully cooling, and is dried in vacuum to obtain a white solid.
(8) Weighing 3-5g of white solid, adding 1-butyl-3-methylimidazole chloride ionic liquid according to the mass ratio of 7:5, and uniformly mixing to obtain the novel composite catalyst composition C 5.
Example 6 (preparation method of aromatic copolyester PBT)
(1) Esterification reaction: 1664g of terephthalic acid, 1080g of 1, 4-butanediol and 3.0g of the composite catalyst composition C 1 g are added into a 5L reaction kettle under the protection of nitrogen atmosphere, the temperature in the kettle is raised to 235 ℃, and the esterification reaction is finished for 5 hours.
(2) Pre-polycondensation reaction: closing the esterification device, opening the polycondensation device, heating the temperature in the kettle to 240 ℃, controlling the air inflow, slowly increasing the vacuum degree in the kettle, and maintaining the pressure for 1h when the vacuum degree in the reaction kettle is 500Pa, so that the pre-polycondensation reaction is finished.
(3) And (3) final polycondensation reaction: heating the temperature in the kettle to 250 ℃, completely closing an air inlet valve, decompressing to a high vacuum condition in a certain time for carrying out final polycondensation reaction, after 2 hours of reaction, enabling the torque to reach about 20N m, closing a vacuum device, and extruding PBT in a molten state by using inert gas; wherein: the yield was 90.5%; the intrinsic viscosity is 1.2 dL/g; the carboxyl end group content was 12.7mol/t.
Example 7 (preparation method of aromatic copolyester PBT)
(1) Esterification reaction: 1664g of terephthalic acid, 1080g of 1, 4-butanediol and 3.0g of the composite catalyst composition C 2 g are added into a 5L reaction kettle under the protection of nitrogen atmosphere, the temperature in the kettle is raised to 235 ℃, and the esterification reaction is finished for 5 hours.
(2) Pre-polycondensation reaction: closing the esterification device, opening the polycondensation device, heating the temperature in the kettle to 240 ℃, controlling the air inflow, slowly increasing the vacuum degree in the kettle, and maintaining the pressure for 1h when the vacuum degree in the reaction kettle is 500Pa, so that the pre-polycondensation reaction is finished.
(3) And (3) final polycondensation reaction: heating the temperature in the kettle to 250 ℃, completely closing an air inlet valve, decompressing to a high vacuum condition in a certain time for carrying out final polycondensation reaction, after 2 hours of reaction, enabling the torque to reach about 20N m, closing a vacuum device, and extruding PBT in a molten state by using inert gas; wherein: the yield was 92.4%; an intrinsic viscosity of 1.0 dL/g; the carboxyl end group content was 10.8mol/t.
Example 8 (preparation method of aromatic copolyester PBT)
(1) Esterification reaction: 1664g of terephthalic acid, 1080g of 1, 4-butanediol and 3.0g of the composite catalyst composition C 3 g are added into a 5L reaction kettle under the protection of nitrogen atmosphere, the temperature in the kettle is raised to 235 ℃, and the esterification reaction is finished for 5 hours.
(2) Pre-polycondensation reaction: closing the esterification device, opening the polycondensation device, heating the temperature in the kettle to 240 ℃, controlling the air inflow, slowly increasing the vacuum degree in the kettle, and maintaining the pressure for 1h when the vacuum degree in the reaction kettle is 500Pa, so that the pre-polycondensation reaction is finished.
(3) And (3) final polycondensation reaction: heating the temperature in the kettle to 250 ℃, completely closing an air inlet valve, decompressing to a high vacuum condition in a certain time for carrying out final polycondensation reaction, after 2 hours of reaction, enabling the torque to reach about 20N m, closing a vacuum device, and extruding PBT in a molten state by using inert gas; wherein: the yield was 93.5%; the intrinsic viscosity is 1.1 dL/g; the carboxyl end group content was 13.4mol/t.
Example 9 (preparation method of aromatic copolyester PBT)
(1) Esterification reaction: 1664g of terephthalic acid, 1080g of 1, 4-butanediol and 3.0g of the composite catalyst composition C 4 g are added into a 5L reaction kettle under the protection of nitrogen atmosphere, the temperature in the kettle is raised to 235 ℃, and the esterification reaction is finished for 6 hours.
(2) Pre-polycondensation reaction: closing the esterification device, opening the polycondensation device, heating the temperature in the kettle to 240 ℃, controlling the air inflow, slowly increasing the vacuum degree in the kettle, and maintaining the pressure for 1h when the vacuum degree in the reaction kettle is 500Pa, so that the pre-polycondensation reaction is finished.
(3) And (3) final polycondensation reaction: heating the temperature in the kettle to 250 ℃, completely closing an air inlet valve, decompressing to a high vacuum condition in a certain time, performing a final polycondensation reaction, after 3 hours of reaction, enabling the torque to reach about 20N m, closing a vacuum device, and extruding PBT in a molten state by using inert gas; wherein: the yield was 87.6%; the intrinsic viscosity is 1.1 dL/g; the carboxyl end group content was 15.3mol/t.
Example 10 (preparation method of aromatic copolyester PBT)
(1) Esterification reaction: 1664g of terephthalic acid, 1080g of 1, 4-butanediol and 3.0g of composite catalyst composition C 5 are added into a 5L reaction kettle under the protection of nitrogen atmosphere, the temperature in the kettle is raised to 235 ℃, the temperature is kept for 1h, and the esterification reaction is finished for 6h.
(2) Pre-polycondensation reaction: closing the esterification device, opening the polycondensation device, heating the temperature in the kettle to 240 ℃, controlling the air inflow, slowly increasing the vacuum degree in the kettle, and maintaining the pressure for 1h when the vacuum degree in the reaction kettle is 500Pa, so that the pre-polycondensation reaction is finished.
(3) And (3) final polycondensation reaction: heating the temperature in the kettle to 250 ℃, completely closing an air inlet valve, decompressing to a high vacuum condition in a certain time for carrying out final polycondensation reaction, after 2 hours of reaction, enabling the torque to reach about 20N m, closing a vacuum device, and extruding PBT in a molten state by using inert gas; wherein: the yield was 91.5%; an intrinsic viscosity of 1.0 dL/g; the carboxyl end group content was 14.9mol/t.
Comparative example 1 (preparation of aromatic PBT copolyester with stannous octoate as catalyst)
The same method as in example 4 was used to prepare a PBT copolyester, except that a single-component catalyst stannous octoate was used as a reaction catalyst, and the torque reached about 20 N.m after 14 hours was no longer increased, and had a tendency to decrease; wherein: the yield was 70.5%; an intrinsic viscosity of 0.6 dL/g; the carboxyl end group content was 28.7mol/t.
Comparative example 2 (preparation of aromatic PBT copolyester with tetrabutyl titanate as catalyst)
A PBT copolyester is prepared by the same method as in example 4, except that a single-component titanate catalyst tetrabutyl titanate is used as a reaction catalyst, and the torque reaches about 20 N.m after 14 hours; wherein: the yield was 87.1%; the intrinsic viscosity was 0.8 dL/g and the carboxyl end group content was 24.5mol/t.
Comparative example 3 (preparation of aromatic PBT copolyester by mixing sodium ethoxide, tetrabutyl titanate, stannous octoate as catalyst)
The same method as in example 4 is adopted to prepare PBT copolyester, except that catalysts of sodium ethoxide, tetrabutyl titanate and stannous octoate are used as reaction catalysts, torque is up to about 20 N.m after 14 hours, the PBT copolyester is not increased any more, and the PBT copolyester has a decreasing trend; wherein: the yield is 90.5 percent, and the intrinsic viscosity is 0.8dL/g; the carboxyl end group content was 26.5mol/t.
Comparative example 4 (preparation of aromatic PBT copolyester by mixing 1-butyl-3-methylimidazole chloride ionic liquid, sodium ethoxide, tetrabutyl titanate, stannous octoate as catalyst)
The same method as in example 4 is adopted to prepare PBT copolyester, except that 1-butyl-3-methylimidazole chloride ionic liquid, sodium ethoxide, tetrabutyl titanate and stannous octoate are used as reaction catalysts, and the torque is about 20 N.m after 10 hours, so that the PBT copolyester does not increase and has a decreasing trend; wherein: the yield was 91.3%, the intrinsic viscosity was 0.8dL/g, and the carboxyl end group content was 22.4mol/t.
Analysis of results:
table 1 PBT preparation test results
| Catalyst species | Catalyst content (wt%) | Esterification time (h) | Polycondensation time (h) | Yield (%) | Intrinsic viscosity (dL/g) | Terminal carboxyl group content (mol/t) | |
| Example 6 | C1 | 0.1 | 5 | 3 | 90.5 | 1.2 | 12.7 |
| Example 7 | C2 | 0.1 | 5 | 3 | 92.4 | 1.0 | 10.8 |
| Example 8 | C3 | 0.1 | 5 | 3 | 93.5 | 1.1 | 13.4 |
| Example 9 | C4 | 0.1 | 6 | 4 | 87.6 | 1.1 | 15.3 |
| Example 10 | C5 | 0.1 | 6 | 3 | 91.5 | 1.0 | 14.9 |
| Comparative example 1 | Stannous octoate | 0.3 | 8 | 6 | 70.5 | 0.6 | 28.7 |
| Comparative example 2 | Tetrabutyl titanate | 0.1 | 8 | 6 | 87.1 | 0.8 | 24.5 |
| Comparative example 3 | Tetrabutyl titanate, sodium ethoxide and stannous octoate | 0.1 | 8 | 6 | 90.5 | 0.8 | 26.5 |
| Comparative example 4 | 1-Butyl-3-methylimidazole chloride, tetrabutyl titanate, sodium ethoxide and stannous octoate | 0.1 | 6 | 4 | 91.3 | 0.8 | 22.4 |
As can be seen from Table 1, examples 6-10 compare with comparative examples 1-3: the PBT using the composite catalyst composition can obviously shorten the esterification time, the non-composite catalyst has poorer catalysis effect, and the PBT copolyester with low melt index, high viscosity and low carboxyl end can be obtained only by longer reaction time. Example 6 and comparative example 2: the titanium catalyst suitable for PBT has poor catalytic effect when preparing PBT, and causes huge energy consumption loss when being industrialized in a large scale. Comparison by comparative example 3 and comparative example 4: compared with the pure mixed addition of tetrabutyl titanate, sodium ethoxide, stannous octoate and other ionic liquids such as 1-butyl-3-methylimidazole chloride, the esterification time can be greatly shortened, and the ionic liquid can be more efficient for carboxyl and hydroxyl of the dicarboxylic acid compound and the dihydroxy compound, so that the polymerization effect is improved, the side reaction is reduced, and the yield is improved. Example 6 and comparative example 4: the nano SiO 2 with better stability effect is adopted as a carrier catalyst in the polycondensation stage, so that the surface of the catalyst can be enlarged, the heat resistance of the catalyst can be greatly improved, the higher catalytic activity is kept, the polycondensation time is reduced, the yield is improved, and the PBT copolyester with low melt index, high viscosity and low carboxyl end group content can be obtained more easily. Example 6 was compared with example 7 and example 8, and it was found that when the nanoscale solid composite catalyst and the amino acid ionic liquid were controlled according to a mass ratio of 8:3, the composite catalyst with the uniformly mixed proportion has the highest catalytic efficiency, the largest reaction activity and the best effect.
Table 2 PBT tensile Strength and elongation at break
| Elongation at break/% | Tensile Strength/MPa | Impact strength kJ/m 2 | |
| Example 6 | 12.0 | 45.0 | 21.5 |
| Example 7 | 11.5 | 44.6 | 22.0 |
| Example 8 | 13.6 | 47.0 | 23.5 |
| Comparative example 2 | 14.1 | 40.0 | 19.1 |
As can be seen from Table 2, examples 4 to 6 of the present application were compared with comparative example 2, and had tensile strengths of 44.6MPa or more and impact strengths of 21.5kJ/m 2 or more.
The foregoing description is only of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention, and all equivalent structures or equivalent processes or direct or indirect application in other related technical fields are included in the scope of the present invention.
Claims (10)
1. The preparation method of the low-end carboxyl polybutylene terephthalate is characterized in that terephthalic acid, 1, 4-butanediol and a composite catalyst composition are added into a reaction kettle together, and the low-end carboxyl polybutylene terephthalate is obtained through esterification, pre-polycondensation and final polycondensation;
The composite catalyst composition comprises a nano-scale solid composite catalyst and an amino acid ionic liquid; the nano-scale solid composite catalyst comprises, by mass, 8 parts of an amino acid ionic liquid and 3 parts of a nano-scale solid composite catalyst;
The nano-scale solid composite catalyst takes nano SiO 2 as a carrier, and sequentially coats titanate, tin compounds, alkali metal catalysts and phosphate from inside to outside;
The amino acid ionic liquid is selected from one of 1-butyl-3-methylimidazole chloride salt and 1-butyl-3-methylimidazole bromide salt.
2. The preparation method according to claim 1, wherein the amount of the composite catalyst composition is 0.05-0.5% of the total weight of the raw materials of the reaction system.
3. The preparation method according to claim 1, wherein the nano SiO 2 is porous silica sphere, the pore diameter is 0.1-10nm, and the particle size is 1-6mm.
4. The method according to claim 2, wherein,
The titanate is at least one of diethyl titanate, tetra-tert-butyl titanate, tetrabutyl titanate and tetraisopropyl titanate;
the tin compound is at least one of stannous octoate, dibutyl tin oxide and dibutyl tin dilaurate;
the phosphate is at least one of triphenyl phosphite, triphenyl phosphate and triethyl phosphate;
The alkali metal catalyst is at least one of sodium ethoxide and sodium tert-butoxide.
5. The method according to claim 4, wherein the molar ratio of the tin compound to the titanate is 1:1-1:2; the mol ratio of the tin compound to the phosphate is 1:1-1:5, a step of; the mol ratio of the tin compound to the alkali metal catalyst is 1:1-1:2.
6. The method according to claim 1, wherein,
The ratio of the molar content of the 1, 4-butanediol to the molar content of the terephthalic acid is 1.3-1.5:1.
7. The method according to claim 1, wherein,
The esterification reaction temperature is 220-235 ℃ and the reaction time is 5-8h;
When the pre-polycondensation reaction is carried out, the pre-polycondensation reaction is carried out for not less than 1h at the temperature of not lower than 240 ℃, and then the pressure is maintained for not less than 1h at the vacuum degree of not more than 500 Pa;
The final polycondensation reaction is carried out for at least 1h under the conditions that the pressure of a vacuum environment is less than 180Pa and the temperature is 250 ℃.
8. The preparation method according to claim 4, wherein the nanoscale solid composite catalyst is prepared by the following method:
S1, according to an isovolumetric impregnation method, placing nano SiO 2 into a first impregnation liquid for impregnation, drying and calcining to obtain a first modified carrier; the first impregnating solution is obtained by dissolving titanate in absolute methanol;
S2, according to an isovolumetric impregnation method, the first modified carrier treated in the step S1 is placed in a second impregnation liquid for impregnation, drying and calcination, so as to obtain a second modified carrier; the second impregnating solution is obtained by dissolving a tin compound in petroleum ether;
s3, according to an isovolumetric impregnation method, the second modified carrier treated in the step S2 is placed in a third impregnation liquid for impregnation and reaction, and after cooling, suction filtration and drying treatment, the nano-scale solid composite catalyst is obtained; the third impregnating solution is prepared by adding an alkali metal catalyst and phosphate into absolute ethyl alcohol, and carrying out reflux stirring reaction for not less than 6 hours at 50-60 ℃.
9. The method according to claim 8, wherein in step S1, the nano SiO 2 is impregnated for not less than 6 hours, and then oven-dried at not less than 100 ℃ for not less than 18 hours; calcining at 550 ℃ or higher for 6 hours or longer;
in the step S2, the dipping time is not less than 6 hours, and then the drying is carried out in an oven at the temperature not lower than 100 ℃ for not less than 18 hours; calcining at 550 ℃ or higher for 6 hours or longer;
in the step S3, an alkali metal catalyst and phosphate are added into absolute ethyl alcohol, and reflux stirring reaction is carried out for more than 8 hours at 60 ℃; the soaking time is not less than 6 hours, and then the drying is carried out in an oven at the temperature of not less than 100 ℃ for not less than 18 hours.
10. A low-end carboxyl terephthalic acid butanediol ester, which is characterized in that the low-end carboxyl terephthalic acid butanediol ester is prepared by the preparation method according to any one of claims 1 to 9; the viscosity of the low-end carboxyl polybutylene terephthalate is 0.8-1.2g/dL, the end carboxyl content is less than 20mol/t, the tensile strength is more than 44.6MPa, and the impact strength is more than 21.5kJ/m 2.
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| CN104540873A (en) * | 2012-06-05 | 2015-04-22 | 三菱化学株式会社 | Production method for polybutylene terephthalate |
| CN110982054A (en) * | 2019-12-28 | 2020-04-10 | 中国科学院过程工程研究所 | Composite catalyst for catalytically synthesizing polycarbonate and method for catalytically synthesizing polycarbonate |
| CN114437321A (en) * | 2021-12-30 | 2022-05-06 | 康辉新材料科技有限公司 | Poly (butylene succinate) and preparation method thereof |
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| CN104540873A (en) * | 2012-06-05 | 2015-04-22 | 三菱化学株式会社 | Production method for polybutylene terephthalate |
| CN110982054A (en) * | 2019-12-28 | 2020-04-10 | 中国科学院过程工程研究所 | Composite catalyst for catalytically synthesizing polycarbonate and method for catalytically synthesizing polycarbonate |
| CN114437321A (en) * | 2021-12-30 | 2022-05-06 | 康辉新材料科技有限公司 | Poly (butylene succinate) and preparation method thereof |
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