CN114536822B - Process for preparing polycaprolactone crystals - Google Patents
Process for preparing polycaprolactone crystals Download PDFInfo
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- CN114536822B CN114536822B CN202011291478.6A CN202011291478A CN114536822B CN 114536822 B CN114536822 B CN 114536822B CN 202011291478 A CN202011291478 A CN 202011291478A CN 114536822 B CN114536822 B CN 114536822B
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- polycaprolactone
- polyvinyl chloride
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- blend film
- crystals
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- 229920001610 polycaprolactone Polymers 0.000 title claims abstract description 68
- 239000004632 polycaprolactone Substances 0.000 title claims abstract description 67
- 239000013078 crystal Substances 0.000 title claims abstract description 44
- 238000004519 manufacturing process Methods 0.000 title claims description 6
- 229920000915 polyvinyl chloride Polymers 0.000 claims abstract description 68
- 239000004800 polyvinyl chloride Substances 0.000 claims abstract description 68
- 239000000203 mixture Substances 0.000 claims abstract description 45
- 238000001816 cooling Methods 0.000 claims abstract description 24
- 238000010438 heat treatment Methods 0.000 claims abstract description 22
- 238000002360 preparation method Methods 0.000 claims abstract description 17
- 239000000758 substrate Substances 0.000 claims abstract description 8
- 230000001939 inductive effect Effects 0.000 claims abstract description 5
- 238000002425 crystallisation Methods 0.000 claims description 30
- 230000008025 crystallization Effects 0.000 claims description 30
- 238000000034 method Methods 0.000 claims description 19
- 238000002156 mixing Methods 0.000 claims description 17
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical group C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 claims description 14
- 238000001035 drying Methods 0.000 claims description 13
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 12
- 239000002904 solvent Substances 0.000 claims description 8
- 238000001291 vacuum drying Methods 0.000 claims description 8
- 230000008569 process Effects 0.000 claims description 7
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 claims description 7
- 239000007788 liquid Substances 0.000 claims description 6
- 229910052757 nitrogen Inorganic materials 0.000 claims description 6
- 238000003892 spreading Methods 0.000 claims description 4
- 230000007480 spreading Effects 0.000 claims description 4
- JWUJQDFVADABEY-UHFFFAOYSA-N 2-methyltetrahydrofuran Chemical compound CC1CCCO1 JWUJQDFVADABEY-UHFFFAOYSA-N 0.000 claims description 3
- 239000000243 solution Substances 0.000 description 16
- 230000000052 comparative effect Effects 0.000 description 13
- 238000012360 testing method Methods 0.000 description 7
- 230000015572 biosynthetic process Effects 0.000 description 5
- 229920000642 polymer Polymers 0.000 description 5
- 238000003756 stirring Methods 0.000 description 4
- 238000004736 wide-angle X-ray diffraction Methods 0.000 description 4
- 229920002678 cellulose Polymers 0.000 description 3
- 239000001913 cellulose Substances 0.000 description 3
- 239000002159 nanocrystal Substances 0.000 description 3
- 238000006467 substitution reaction Methods 0.000 description 3
- 238000005033 Fourier transform infrared spectroscopy Methods 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 239000000155 melt Substances 0.000 description 2
- WZFUQSJFWNHZHM-UHFFFAOYSA-N 2-[4-[2-(2,3-dihydro-1H-inden-2-ylamino)pyrimidin-5-yl]piperazin-1-yl]-1-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)ethanone Chemical compound C1C(CC2=CC=CC=C12)NC1=NC=C(C=N1)N1CCN(CC1)CC(=O)N1CC2=C(CC1)NN=N2 WZFUQSJFWNHZHM-UHFFFAOYSA-N 0.000 description 1
- DEXFNLNNUZKHNO-UHFFFAOYSA-N 6-[3-[4-[2-(2,3-dihydro-1H-inden-2-ylamino)pyrimidin-5-yl]piperidin-1-yl]-3-oxopropyl]-3H-1,3-benzoxazol-2-one Chemical compound C1C(CC2=CC=CC=C12)NC1=NC=C(C=N1)C1CCN(CC1)C(CCC1=CC2=C(NC(O2)=O)C=C1)=O DEXFNLNNUZKHNO-UHFFFAOYSA-N 0.000 description 1
- 238000001157 Fourier transform infrared spectrum Methods 0.000 description 1
- MKYBYDHXWVHEJW-UHFFFAOYSA-N N-[1-oxo-1-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)propan-2-yl]-2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carboxamide Chemical compound O=C(C(C)NC(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F)N1CC2=C(CC1)NN=N2 MKYBYDHXWVHEJW-UHFFFAOYSA-N 0.000 description 1
- NIPNSKYNPDTRPC-UHFFFAOYSA-N N-[2-oxo-2-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)ethyl]-2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carboxamide Chemical compound O=C(CNC(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F)N1CC2=C(CC1)NN=N2 NIPNSKYNPDTRPC-UHFFFAOYSA-N 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 229920003232 aliphatic polyester Polymers 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000013270 controlled release Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 229940079593 drug Drugs 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000012847 fine chemical Substances 0.000 description 1
- 238000011534 incubation Methods 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000005022 packaging material Substances 0.000 description 1
- 230000003071 parasitic effect Effects 0.000 description 1
- -1 polyethylene Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920002959 polymer blend Polymers 0.000 description 1
- 229920006254 polymer film Polymers 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 238000004080 punching Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000004528 spin coating Methods 0.000 description 1
- 230000005469 synchrotron radiation Effects 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
- B29D7/00—Producing flat articles, e.g. films or sheets
- B29D7/01—Films or sheets
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
- C08J5/18—Manufacture of films or sheets
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2027/00—Use of polyvinylhalogenides or derivatives thereof as moulding material
- B29K2027/06—PVC, i.e. polyvinylchloride
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2067/00—Use of polyesters or derivatives thereof, as moulding material
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2367/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
- C08J2367/04—Polyesters derived from hydroxy carboxylic acids, e.g. lactones
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2427/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers
- C08J2427/02—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment
- C08J2427/04—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment containing chlorine atoms
- C08J2427/06—Homopolymers or copolymers of vinyl chloride
Abstract
The invention discloses a preparation method of polycaprolactone crystal, which comprises the following steps: (1) Heating the polycaprolactone-polyvinyl chloride blend film to 80-110 ℃ at a heating rate of 10-30 ℃/min, and preserving heat for 10-30 min; wherein the polycaprolactone-polyvinyl chloride blend film is not attached to the orientation-inducing substrate; (2) Cooling the polycaprolactone-polyvinyl chloride blend film obtained in the step (1) to 35-45 ℃ at a cooling rate of 55-65 ℃/min; (3) Stretching and crystallizing the polycaprolactone-polyvinyl chloride blend film obtained in the step (2) at the stretching rate of 90-110 mu m/s and the stretching ratio of 3.5-5.5 at the temperature of 35-45 ℃ to obtain polycaprolactone crystals with only a-axis orientation and b-axis orientation coexisting. The invention can obtain polycaprolactone crystals with specific orientation.
Description
Technical Field
The invention relates to a preparation method of polycaprolactone crystal.
Background
Polycaprolactone (PCL) is a semi-crystalline aliphatic polyester having a single crystalline form. Because of its good biocompatibility and degradability, it can be used in the aspects of drug controlled release carrier, packaging material and operation suture, etc., and is receiving extensive attention. However, crystal studies on PCL remain relatively few.
CN108084477a discloses a method for preparing a high molecular oriented film. (1) Preparing a first polymer oriented film by adopting a melt stretching method, and attaching the first polymer oriented film on a substrate; (2) And adhering the second polymer blend solution on the first polymer oriented film by adopting a spin coating method to form a second polymer film, and then carrying out heat treatment to obtain the polymer oriented film with parallel platelets. The above method requires first preparing a first polymer oriented film as a substrate, and is complicated in process. CN107043525a discloses a method for preparing a polycaprolactone/cellulose composite material with controllable polycaprolactone crystallization. The patent document prepares a composite material by blending cellulose nanocrystals with different degrees of substitution with polycaprolactone, and the acetylated cellulose nanocrystals with different degrees of substitution play a role in regulating and controlling the crystallization of the polycaprolactone. The method needs to adopt nanocrystals, and industrialization is not easy to realize.
In addition, the study of blends of PCL with PVC was performed by the scholars, but only unoriented spherulites were obtained. In order to orient the PCL crystals, an attached crystallization approach may be employed. However, the parasitic crystallization conditions are severe, and the post-treatment has a great influence on the performance of the PCL film. The scholars formed c-axis oriented PCL crystals on an oriented polyethylene substrate.
Disclosure of Invention
In view of the above, the present invention aims to provide a method for preparing polycaprolactone crystals. The preparation method can form polycaprolactone crystals with only a-axis orientation and b-axis orientation coexisting. The polycaprolactone crystal has more excellent comprehensive performance.
The invention provides a preparation method of polycaprolactone crystal, which comprises the following steps:
(1) Heating the polycaprolactone-polyvinyl chloride blend film to 80-110 ℃ at a heating rate of 10-30 ℃/min, and preserving heat for 10-30 min; wherein the polycaprolactone-polyvinyl chloride blend film is not attached to the orientation-inducing substrate;
(2) Cooling the polycaprolactone-polyvinyl chloride blend film obtained in the step (1) to 35-45 ℃ at a cooling rate of 55-65 ℃/min;
(3) Stretching and crystallizing the polycaprolactone-polyvinyl chloride blend film obtained in the step (2) at the stretching rate of 90-110 mu m/s and the stretching ratio of 3.5-5.5 at the temperature of 35-45 ℃ to obtain polycaprolactone crystals with only a-axis orientation and b-axis orientation coexisting.
According to the preparation method of the present invention, preferably, in the step (1), the heating rate is 15 to 25 ℃/min, the heating temperature is 90 to 110 ℃, and the heat preservation time is 15 to 30min.
According to the preparation method of the invention, preferably, in the step (2), liquid nitrogen is adopted for cooling, and the cooling rate is 57-63 ℃/min.
According to the production method of the present invention, preferably, in the step (3), the stretching rate is 95 to 105 μm/s and the stretching ratio is 3.5 to 5.
According to the production method of the present invention, preferably, the crystallization includes: isothermal crystallization is carried out at 35-45 ℃ for 300-1200 min.
According to the production method of the present invention, preferably, one of the following conditions is provided:
1) The stretching ratio is 3.5-4, and the isothermal crystallization time is 500-1200 min; or alternatively
2) The stretching ratio is more than 4 and less than 5, and the isothermal crystallization time is 500-1000 min.
According to the preparation method of the present invention, preferably, the stretching ratio is 5 to 5.5, and the isothermal crystallization time is 300 to 800 minutes.
The preparation method according to the present invention preferably further comprises the steps of:
uniformly spreading a blending solution formed by polycaprolactone, polyvinyl chloride and a solvent on the surface of a container, and drying and stripping to obtain a polycaprolactone-polyvinyl chloride blending film;
wherein the solvent is tetrahydrofuran or 2-methyltetrahydrofuran; in the blending solution, the mass ratio of the polycaprolactone to the polyvinyl chloride is 70-80:20-30; the total mass fraction of polycaprolactone and polyvinyl chloride is 4.5-5.5 wt%.
According to the preparation method of the invention, preferably, the mass ratio of polycaprolactone to polyvinyl chloride is 70-75:20-30; the total mass fraction of polycaprolactone and polyvinyl chloride is 4.7-5.3wt%; the drying is vacuum drying, the drying temperature is 30-45 ℃, and the drying time is 12-72 h.
According to the preparation method of the present invention, preferably, the thickness of the polycaprolactone-polyvinyl chloride blend film is 60 to 180 μm.
By controlling the cooling rate and the specific stretching ratio, the invention can obtain polycaprolactone crystals with only a-axis orientation and b-axis orientation coexisting, and the polycaprolactone crystals do not contain c-axis orientation. Furthermore, the method for preparing the polycaprolactone crystal is simple and efficient.
Detailed Description
The present invention will be further described with reference to specific examples, but the scope of the present invention is not limited thereto.
The invention provides a preparation method of polycaprolactone crystal, which comprises the following steps: preparing a polycaprolactone-polyvinyl chloride blend film; and a step of forming polycaprolactone crystals. The following is a detailed description.
< preparation step of polycaprolactone-polyvinyl chloride blend film >
And forming a blending solution by polycaprolactone, polyvinyl chloride and a solvent. Specifically, polycaprolactone and polyvinyl chloride are mixed with a solvent to obtain a blend solution.
The solvent is tetrahydrofuran or 2-methyltetrahydrofuran, preferably tetrahydrofuran. The total mass fraction of polycaprolactone and polyvinyl chloride in the blend solution is 4.5-5.5 wt%, preferably 4.7-5.3 wt%, more preferably 5.0-5.3 wt%.
In the blending solution, the mass ratio of the polycaprolactone to the polyvinyl chloride is 70-80:20-30, preferably 70-75:20-30; more preferably 70 to 75:25 to 30. This facilitates the formation of polycaprolactone crystals in which the a-axis orientation and the b-axis orientation coexist.
In the invention, when polycaprolactone and polyvinyl chloride are mixed with a solvent, the mixture is heated and stirred at 35-50 ℃ to obtain a blending solution. The heating temperature may be 35 to 45 ℃, preferably 37 to 45 ℃, more preferably 40 to 43 ℃. The stirring rate is 400 to 700r/min, preferably 400 to 600r/min, more preferably 500 to 600r/min. The stirring time is 1 to 24 hours, preferably 2 to 15 hours, more preferably 2 to 8 hours. This facilitates the formation of a uniform blend solution.
According to one embodiment of the invention, polycaprolactone and polyvinyl chloride are dispersed in tetrahydrofuran, and stirred at a stirring rate of 500-600 r/min for 2-15 h at a temperature of 35-45 ℃ to obtain a blending solution with a total mass fraction of 4.7-5.3 wt%, wherein the mass ratio of the polycaprolactone to the polyvinyl chloride is 70-80:20-30.
Uniformly spreading the blending solution on the surface of a container, and drying and stripping to obtain the polycaprolactone-polyvinyl chloride blending film. The container may be a petri dish or the like. In this step, the drying is vacuum drying, and the drying temperature is 30 to 45 ℃, preferably 30 to 40 ℃, more preferably 35 to 40 ℃. The drying time is 12 to 72 hours, preferably 24 to 60 hours, more preferably 36 to 50 hours.
The thickness of the polycaprolactone-polyvinyl chloride blend film obtained after peeling is 60 to 180. Mu.m, preferably 80 to 120. Mu.m, more preferably 95 to 105. Mu.m. This facilitates stretching to obtain oriented polycaprolactone crystals. The caprolactone-polyvinyl chloride blend film obtained after peeling was not attached to any orientation-inducing substrate.
According to one specific embodiment of the invention, a solution injection method is adopted to uniformly spread a polycaprolactone-polyvinyl chloride blending solution with the total mass fraction of 4.7-5.3 wt% in a culture dish, and the polycaprolactone-polyvinyl chloride blending film is subjected to vacuum drying and stripping. The vacuum drying temperature is 30-45 ℃, the vacuum degree of vacuum drying is 0.1MPa, and the vacuum drying time is 12-72 h. The thickness of the polycaprolactone-polyvinyl chloride blend film obtained after stripping is 60-180 mu m.
< step of Forming polycaprolactone Crystal >
Heating the polycaprolactone-polyvinyl chloride blend film to 80-110 ℃ at a heating rate of 10-30 ℃/min, and preserving heat for 10-30 min; wherein the polycaprolactone-polyvinyl chloride blend film is not attached to the orientation inducing substrate. The heating rate may be 10 to 30℃per minute, preferably 15 to 25℃per minute, more preferably 20 to 25℃per minute. The polycaprolactone-polyvinyl chloride blend film may be heated to 80 to 110 ℃, preferably to 90 to 110 ℃, more preferably to 95 to 105 ℃. And heating to a target temperature, and then preserving heat. The incubation time may be 15 to 30 minutes, preferably 20 to 30 minutes, more preferably 20 to 25 minutes. This is advantageous in obtaining polycaprolactone crystals in which the a-axis orientation and the b-axis orientation coexist.
Then, the polycaprolactone-polyvinyl chloride blend film obtained in the steps is cooled to 35-45 ℃ at a cooling rate of 55-65 ℃/min. The cooling rate is preferably 57 to 63 ℃/min, more preferably 60 to 63 ℃/min. The temperature reduction is preferably carried out using liquid nitrogen. The polycaprolactone-polyvinyl chloride blend film obtained is cooled to 35 to 45 ℃, preferably 37 to 43 ℃, more preferably 40 to 43 ℃. This facilitates the formation of polycaprolactone crystals in which the a-axis and b-axis orientations coexist.
The polycaprolactone-polyvinyl chloride blend film obtained in the above steps is stretched and crystallized at a stretching rate of 90-110 mu m/s at 35-45 ℃ and a stretching ratio of 3.5-5.5, and polycaprolactone crystals in which only the a-axis orientation and the b-axis orientation coexist are obtained. The stretching temperature may be 35 to 45 ℃, preferably 37 to 43 ℃, more preferably 40 to 43 ℃.
In the present invention, the stretching rate may be 90 to 110. Mu.m/s, preferably 95 to 110. Mu.m/s, more preferably 90 to 105. Mu.m/s. The prior art generally employs higher stretching rates, resulting in failure to form polycaprolactone crystals that coexist with only a-axis orientation and b-axis orientation. The invention adopts proper low-speed stretching, which is beneficial to the formation of a-axis oriented crystals and b-axis oriented crystals.
In the present invention, the stretching ratio is 3.5 to 5.5, preferably 3.5 to 5, more preferably 4 to 5. The present invention has unexpectedly found that the draw ratio has an important effect on the crystal orientation, which is not a conventional technical means in the art. When the stretching ratio exceeds the above range, polycaprolactone crystals in which only the a-axis orientation and the b-axis orientation coexist cannot be obtained. The stretching ratio is lower than 3.5, and only a-axis oriented crystals can be obtained; the stretching ratio was higher than 5.5, and only b-axis oriented crystals could be obtained.
In the polycaprolactone-polyvinyl chloride blend film, the mass ratio of the polycaprolactone to the polyvinyl chloride is 70-80:20-30. This is consistent with the mass ratio in the blend solution formed.
The crystallization process of the present invention comprises: isothermal crystallization is carried out at 35-45 ℃ for 300-1200 min.
The isothermal crystallization of the present invention has one of the following conditions: when the draw ratio is 3.5 to 4, the isothermal crystallization time is 500 to 1200 minutes, preferably 600 to 1000 minutes, more preferably 700 to 800 minutes. Or when the draw ratio is more than 4 and less than 5, the isothermal crystallization time is 500 to 1000 minutes, preferably 600 to 1000 minutes, more preferably 650 to 800 minutes. Or when the draw ratio is 5 to 5.5, the isothermal crystallization time is 300 to 800 minutes, preferably 400 to 700 minutes, more preferably 500 to 600 minutes. Different stretching ratios are matched with different crystallization times, so that polycaprolactone crystals with coexisting a-axis orientation and b-axis orientation can be formed fully.
According to one embodiment of the invention, the polycaprolactone-polyvinyl chloride blend film is heated to 80-110 ℃ at a heating rate of 10-30 ℃/min and is kept for 10-30 min; cooling the obtained polycaprolactone-polyvinyl chloride blend film by liquid nitrogen, and cooling to 35-45 ℃ at a cooling rate of 55-65 ℃/min; and stretching and crystallizing the obtained polycaprolactone-polyvinyl chloride blend film at the stretching rate of 90-110 mu m/s at the temperature of 35-45 ℃ and the stretching ratio of 3.5-5.5 to obtain polycaprolactone crystals.
According to a preferred embodiment of the invention, the polycaprolactone-polyvinyl chloride blended tensile bar is heated to 90-110 ℃ at a heating rate of 15-25 ℃/min and is kept for 20-30 min; cooling the obtained polycaprolactone-polyvinyl chloride blend film by liquid nitrogen, and cooling to 35-45 ℃ at a cooling rate of 57-63 ℃/min; and stretching and crystallizing the obtained polycaprolactone-polyvinyl chloride blend film at the temperature of 37-43 ℃ at the stretching rate of 95-110 mu m/s and the stretching ratio of 3.5-5 to obtain the polycaprolactone crystal.
The test methods used in the examples, comparative examples and experimental examples are described below:
fourier transform infrared spectroscopy test: FTIR-650 Fourier transform infrared spectrometer is adopted, and the test wave band is 400-4000 cm -1 The scanning times are 8 times, the scanning interval is 2min, and the resolution of the instrument is 4cm -1 。
Transmission wide angle X-ray diffraction test: a transmission wide-angle X-ray diffraction apparatus of the beijing synchrotron radiation 1W2A line station was used, and wide-angle X-ray diffraction was used to characterize the crystal orientation of PCL. The prepared tensile bars were fixed on a sample stage, exposed for 20s, and diffraction signals were collected by Mar165CCD (resolution: 2048×2048, pixel size: 79 μm×79 μm) and X-ray wavelength: 0.154nm.
The raw materials used in the examples and comparative examples are described below:
polycaprolactone: purchased from Aldrich corporation. Wherein the number average molecular weight is 70000 to 90000g/mol.
Polyvinyl chloride: purchased from Aldrich corporation. Wherein the number average molecular weight was 99000g/mol.
Tetrahydrofuran: purchased from Beijing Tong Guangdong fine chemical industry company, and the purity is more than or equal to 99%.
Stretching ratio: length ratio of the blended film after stretching to before stretching.
Preparation example 1 preparation of polycaprolactone-polyvinyl chloride blend film
(1) The polycaprolactone and the polyvinyl chloride with the mass ratio of 70:30 are dispersed in tetrahydrofuran and stirred for 6 hours at the stirring speed of 600r/min at the temperature of 40 ℃ to obtain a blending solution with the total mass fraction of the polycaprolactone and the polyvinyl chloride of 5wt%.
(2) Uniformly spreading the blending solution in a 75ml culture dish; drying in a vacuum drying oven at 35deg.C under vacuum degree of 0.1MPa for 48 hr, and slightly peeling the blended film from the culture dish to obtain polycaprolactone-polyvinyl chloride blended film with thickness of 100 μm. And forming the dumbbell-shaped polycaprolactone-polyvinyl chloride blend film by passing the polycaprolactone-polyvinyl chloride blend film through a dumbbell-shaped stretching spline die and a pneumatic sample punching machine.
Example 1
Fixing the dumbbell-shaped polycaprolactone-polyvinyl chloride blend film obtained in preparation example 1 on a stretcher, and placing the film in an infrared spectrometer for scanning; then heating the dumbbell-shaped polycaprolactone-polyvinyl chloride blend film to 100 ℃ at a heating rate of 20 ℃/min, and preserving heat for 20min;
cooling the dumbbell-shaped polycaprolactone-polyvinyl chloride blend film by liquid nitrogen, and rapidly cooling to 40 ℃ at a cooling rate of 60 ℃/min;
the polycaprolactone-polyvinyl chloride blend film is stretched at a stretching rate of 100 mu m/s and a stretching ratio of 4 at 40 ℃, and is subjected to isothermal crystallization for 750min at 40 ℃ to obtain polycaprolactone crystals.
Example 2
The difference from example 1 is only that the draw ratio is 5 and the isothermal crystallization time is 550min.
Comparative example 1
The only difference from example 1 is that the draw ratio was 3.
Comparative example 2
The only difference from example 2 is that the draw ratio was 6.
Comparative example 3
The difference from example 1 is that the stretching is directly performed at room temperature, without the heating and cooling process of example 1.
Comparative example 4
The difference from example 1 is that the polycaprolactone-polyvinyl chloride blend film was not stretched (i.e., the stretch ratio was 1).
Experimental example 1 crystallization kinetics of polycaprolactone Crystal
The products of examples 1-2 and comparative examples 1-4 were subjected to Fourier transform infrared spectrum scanning test during crystal formation, and the wavelength associated with the crystallinity was selected to be 731cm -1 Is a characteristic peak of (2). Analysis of the relative intensity of this band over time shows that, at the initial stage of crystallization, the crystallization rate is slow due to the melt state of the polycaprolactone polymer molecular chain, and as the crystal nuclei are generated, the crystallization rate is gradually increased, and at the final stage of crystallization, the content of uncrystallized polycaprolactone is significantly reduced, and the collision between platelets occurs, the crystallization rate is slowed down, until the crystallization is completed, and the crystallinity is no longer changed.
Experimental example 2-Transmission Wide-angle X-ray diffraction test of polycaprolactone Crystal
The intermediate portions of the products obtained in examples 1 to 2 and comparative examples 1 to 4 were fixed to the sample stage, respectively, to ensure that the intermediate portions were located at the detection holes. The exposure time was determined by observing the intensity of the diffraction signal, which was collected by a Mar165CCD detector, with an exposure time of 20s being selected for this experiment. The test results are shown in Table 2 below. Table 1 shows the process parameters of examples 1 to 2 and comparative examples 1 to 4.
Table 1 process parameters
| Numbering device | Draw ratio | Whether or not to go through the heating and cooling processes |
| Example 1 | 4 | Is that |
| Example 2 | 5 | Is that |
| Comparative example 1 | 3 | Is that |
| Comparative example 2 | 6 | Is that |
| Comparative example 3 | 4 | Whether or not |
| Comparative example 4 | 1 | Is that |
Table 2 test results
As is clear from tables 1 and 2, polycaprolactone crystals having a specific orientation in which only the a-axis orientation and the b-axis orientation coexist were obtained by using the specific stretching conditions and the stretching ratios of the present invention.
The present invention is not limited to the above-described embodiments, and any modifications, improvements, substitutions, and the like, which may occur to those skilled in the art, fall within the scope of the present invention without departing from the spirit of the invention.
Claims (6)
1. A method for preparing polycaprolactone crystals, comprising the steps of:
(1) Heating the polycaprolactone-polyvinyl chloride blend film to 80-110 ℃ at a heating rate of 10-30 ℃/min, and preserving heat for 10-30 min; wherein the polycaprolactone-polyvinyl chloride blend film is not attached to the orientation-inducing substrate;
(2) Cooling the polycaprolactone-polyvinyl chloride blend film obtained in the step (1) to 35-45 ℃ at a cooling rate of 55-65 ℃/min;
(3) Stretching and crystallizing the polycaprolactone-polyvinyl chloride blend film obtained in the step (2) at the temperature of 35-45 ℃ at the stretching rate of 90-110 mu m/s and the stretching ratio of 3.5-5.5 to obtain polycaprolactone crystals with only a-axis orientation and b-axis orientation coexisting;
wherein the crystallization comprises: isothermal crystallization is carried out at 35-45 ℃; has one of the following conditions:
1) The stretching ratio is 3.5-4, and the isothermal crystallization time is 500-1200 min; or alternatively
2) The stretching ratio is more than 4 and less than 5, and the isothermal crystallization time is 500-1000 min; or alternatively
3) The stretching ratio is 5-5.5, and the isothermal crystallization time is 300-800 min;
the preparation method further comprises the following steps:
uniformly spreading a blending solution formed by polycaprolactone, polyvinyl chloride and a solvent on the surface of a container, and drying and stripping to obtain the polycaprolactone-polyvinyl chloride blending film;
wherein the solvent is tetrahydrofuran or 2-methyltetrahydrofuran; in the blending solution, the mass ratio of the polycaprolactone to the polyvinyl chloride is 70-80:20-30; the total mass fraction of polycaprolactone and polyvinyl chloride is 4.5-5.5 wt%.
2. The preparation method according to claim 1, wherein in the step (1), the heating rate is 15-25 ℃/min, the heating temperature is 90-110 ℃, and the holding time is 15-30 min.
3. The method according to claim 1, wherein in the step (2), liquid nitrogen is used for cooling, and the cooling rate is 57-63 ℃/min.
4. The process according to claim 3, wherein in the step (3), the stretching rate is 95 to 105 μm/s and the stretching ratio is 3.5 to 5.
5. The method of manufacturing according to claim 1, characterized in that:
the mass ratio of the polycaprolactone to the polyvinyl chloride is 70-75:20-30; the total mass fraction of polycaprolactone and polyvinyl chloride is 4.7-5.3wt%;
the drying is vacuum drying, the drying temperature is 30-45 ℃, and the drying time is 12-72 h.
6. The method according to claim 1, wherein the polycaprolactone-polyvinyl chloride blend film has a thickness of 60 to 180 μm.
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